Kai Ishida, Mina Matsubara, Miharu Nagahashi, Yushi Onoda, Toshihiko Aizawa, Shigeharu Yamauchi, Yasuo Fujikawa, Tomotake Tanaka, Yasuko Kadomura-Ishikawa, Takashi Uebanso, Masatake Akutagawa, Kazuaki Mawatari and Akira Takahashi : Efficacy of ultraviolet-light emitting diodes in bacterial inactivation and DNA damage via sensitivity evaluation using multiple wavelengths and bacterial strains., Archives of Microbiology, Vol.207, No.6, 2025.
(要約)
Ultraviolet-light emitting diodes (UV-LEDs) have garnered attention for their efficient bacterial inactivation. However, in previous studies, it has been difficult to strictly compare the bacterial inactivation effect of UV irradiation among wavelengths differing by a few nanometers because detailed UV irradiation conditions for comparison, such as the LED characteristics at each wavelength and power supply characteristics, have not been established. Therefore, this study aimed to evaluate UV inactivation of 10 bacterial strains across 13 wavelengths (250-365 nm) using a standardized irradiation system previously reported to identify the most effective wavelengths for prevention of bacterial infection and contamination. Bacterial inactivation dose response curves were generated to determine the fluence required to archive 1-3 log10 inactivation. The results indicated that Gram-negative bacteria exhibited higher initial sensitivity compared with Gram-positive bacteria. Wavelength-dependent inactivation peaked at 263-270 nm, correlating strongly with cyclobutane pyrimidine dimer production (r > 0.9 for most strains). Deconvolution analysis confirmed that bacterial inhibition was maximal around 267.6 nm. Furthermore, UV-LEDs outperformed low-pressure mercury lamps in terms of bacterial inactivation under equivalent fluences, attributed to differences in spectral emission profiles. These findings will help optimize UV-LED sterilization methods for broader applications in microbial control.
Aya Nakai, Shiho Fukushima, Kazuaki Mawatari, Akira Takahashi, Takeshi Nikawa, Shintaro Inoue, Takahito Watanabe, Taro Mito and Katsuyuki Miyawaki : Differential Expression of Key Isoflavone Synthesis Genes in Soybean Sprouts under Two LED Treatments, ACS Agricultural Science & Technology, 2025.
(要約)
Soybean seeds and sprouts contain isoflavones, including aglycones, glucosides, and malonylated glucosides, and their contents vary across soybean varieties. During germination and photomorphogenesis, blue light-emitting diode (LED) irradiation suppressed hypocotyl growth and enhanced the expression levels of chalcone synthase 7, isoflavone synthase (IFS), and isoflavone reductase (IFR). Conversely, red LED irradiation enhanced hypocotyl growth and decreased the expression levels of IFS and IFR. The contents of some glycosides or malonylated glycosides in sprouts and young green soybeans were significantly higher under blue LED irradiation than under red LED irradiation. These results imply that blue light more effectively increased the concentrations of some isoflavones during early germination and/or hydroponics cultivation.
Tran Quang Duc, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Elucidating the Capacity and Mechanism of Lactiplantibacillus plantarum in Synthesizing Essential Amino Acids from Non-Essential Amino Acids in a Novel Severely Deficient Medium, Applied Microbiology, Vol.5, No.1, 16, 2025.
Shintaro Inoue, Kai Fujie, Taiki Hamaguchi, Yoshiyasu Ishimaru, Katsuyuki Miyawaki, Akira Takahashi, Takeshi Nikawa, Sumihare Noji, Takahito Watanabe and Taro Mito : Lineage-specific duplication and functional diversification of DOPA-decarboxylase genes in the Gryllidae family, as revealed in Gryllus bimaculatus., Insect Biochemistry and Molecular Biology, Vol.177, No.104246, 2025.
(要約)
The DOPA-decarboxylase (DDC) gene is crucial for dopamine synthesis and influences various biological functions in insects, including body coloration, behavior, learning, and sleep. However, its evolutionary impact remains largely unexplored. This study reports on the tandem duplication of two bona fide ddc genes (ddc1 and ddc2) in the Gryllidae cricket family. We herein investigated the function of ddc1 and ddc2 using Gryllus bimaculatus (Gb) as a model. Our results revealed that Gb'ddc1 was expressed systemically, with its expression being higher immediately after molting compared to the stage following melanin pigmentation. In homozygous knockout mutants of Gb'ddc1, generated via CRISPR/Cas9, reduced body color pigmentation and had translucent cuticles, decreased dopamine levels, and over-accumulated DOPA. These mutants died shortly after hatching, likely due to cuticle defects, underscoring the essential role of dopamine, produced by Gb'ddc1, in melanin synthesis. Conversely, Gb'ddc2 expression was confined to the ovary and was not up-regulated after molting. Homozygous knockout mutants of Gb'ddc2 exhibited no body color defects, whereas hatchability and embryonic development rates were significantly reduced. Interestingly, dopamine levels in the ovaries were significantly elevated in Gb'ddc2 mutants. This suggests that normal ovarian dopamine levels, modulated by Gb'ddc2, are vital for fertility maintenance. The function of Gb'ddc2 differs from that of typical ddc, indicating neofunctionalization through evolutionary duplication. Overall, Gb'ddc1 and Gb'ddc2 have distinct functions, and precise regulation of ovarian dopamine levels using these two ddc genes may have enhanced cricket fertility.
K. Shinoda, Kazuaki Mawatari, N. T. K. Bui, Y. Kadomura-Ishikawa, Takashi Uebanso, H. Hirakawa, K. Awamoto, M. Wakitani, T. Shinoda and Akira Takahashi : Development of mercury-free far-UVC light source using Luminous Array Film technology and its germicidal effects, IEEE Access, 1, 2025.
(要約)
Far-UVC has emerged as a promising alternative for ultraviolet germicidal irradiation (UVGI). We developed a novel far-UVC light source using Luminous Array Film (LAFi), which excites phosphors by plasma discharge in a neon–xenon gas mixture within a glass tube. An optimal phosphor composition was determined, comprising aluminum phosphate, lutetium phosphate, and scandium. The plasma light module (PLM228) emits far-UVC radiation with a peak wavelength of 228 nm. Improvements in emission intensity and ozone generation suppression were achieved by modifying the glass materials. Escherichia coli, methicillin-resistant and methicillin-sensitive Staphylococcus aureus, and influenza A virus were inactivated by approximately 99.9
(キーワード)
Glass Electrodes Discharges (electric) Phosphors Plasmas Radiation effects Gases Surface discharges Substrates Inverters far-UVC ultraviolet large area light source mercury-free plasma discharge Luminous Array Film disinfection bacteria virus
Yushi Onoda, Miharu Nagahashi, Michiyo Yamashita, Shiho Fukushima, Toshihiko Aizawa, Shigeharu Yamauchi, Yasuo Fujikawa, Tomotake Tanaka, Yasuko Kadomura-Ishikawa, Kai Ishida, Takashi Uebanso, Kazuaki Mawatari, R Ernest Blatchley and Akira Takahashi : Accumulated melanin in molds provides wavelength-dependent UV tolerance., Photochemical & Photobiological Sciences, Vol.23, No.9, 1791-1806, 2024.
(要約)
Fungal contamination poses a serious threat to public health and food safety because molds can grow under stressful conditions through melanin accumulation. Although ultraviolet (UV) irradiation is popular for inhibiting microorganisms, its effectiveness is limited by our insufficient knowledge about UV tolerance in melanin-accumulating molds. In this study, we first confirmed the protective effect of melanin by evaluating the UV sensitivity of young and mature spores. Additionally, we compared UV sensitivity between spores with accumulated melanin and spores prepared with melanin biosynthesis inhibitors. We found that mature spores were less UV-sensitive than young spores, and that reduced melanin accumulation by inhibitors led to reduced UV sensitivity. These results suggest that melanin protects cells against UV irradiation. To determine the most effective wavelength for inhibition, we evaluated the wavelength dependence of UV tolerance in a yeast (Rhodotorula mucilaginosa) and in molds (Aspergillus fumigatus, Cladosporium halotolerans, Cladosporium sphaerospermum, Aspergillus brasiliensis, Penicillium roqueforti, and Botrytis cinerea). We assessed UV tolerance using a UV-light emitting diode (LED) irradiation system with 13 wavelength-ranked LEDs between 250 and 365 nm, a krypton chlorine (KrCl) excimer lamp device, and a low pressure (LP) Hg lamp device. The inhibition of fungi peaked at around 270 nm, and most molds showed reduced UV sensitivity at shorter wavelengths as they accumulated pigment. Absorption spectra of the pigments showed greater absorption at shorter wavelengths, suggesting greater UV protection at these wavelengths. These results will assist in the development of fungal disinfection systems using UV, such as closed systems of air and water purification.
Ryo Higashiyama, Yuna Kanda, Takaaki Shimohata, Kai Ishida, Shiho Fukushima, Kohei Yamazaki, Takashi Uebanso, Kazuaki Mawatari, Takashige Kashimoto and Akira Takahashi : Characterization of Outer Membrane Vesicles Produced by Vibrio vulnificus, The Journal of Medical Investigation : JMI, Vol.71, No.1,2, 102-120, 2024.
(要約)
Vibrio vulnificus (V. vulnificus) is a halophilic gram-negative bacterium that inhabits coastal warm water and induce severe diseases such as primary septicemia. To investigate the mechanisms of rapid bacterial translocation on intestinal infection, we focused on outer membrane vesicles (OMVs), which are extracellular vesicles produced by Gram-negative bacteria and deliver virulence factors. However, there are very few studies on the pathogenicity or contents of V. vulnificus OMVs (Vv-OMVs). In this study, we investigated the effects of Vv-OMVs on host cells. Epithelial cells INT407 were stimulated with purified OMVs and morphological alterations and levels of lactate dehydrogenase (LDH) release were observed. In cells treated with OMVs, cell detachment without LDH release was observed, which exhibited different characteristics from cytotoxic cell detachment observed in V. vulnificus infection. Interestingly, OMVs from a Vibrio Vulnificus Hemolysin (VVH) and Multifunctional-autoprocessing repeats-in -toxin (MARTX) double-deletion mutant strain also caused cell detachment without LDH release. Our results suggested that the proteolytic function of a serine protease contained in Vv-OMVs may contribute to pathogenicity of V. vulnificus by assisting bacterial translocation. This study reveals a new pathogenic mechanism during V. vulnificus infections. J. Med. Invest. 71 : 102-112, February, 2024.
Junko Kido, Takaaki Shimohata, Mutsumi Aihara, Akari Tsunedomi, Sho Hatayama, Sachie Amano, Yuri Sato, Shiho Fukushima, Yuna Kanda, Aya Tentaku, Kai Ishida, Hitomi Iba, Yumi Harada, Takashi Uebanso, Kazuaki Mawatari, Masatake Akutagawa and Akira Takahashi : Reduction of Campylobacter jejuni contamination by using UVA-LED and sodium hypochlorite on the surface of chicken meat., Journal of Microorganism Control, Vol.29, No.2, 91-97, 2024.
(要約)
Campylobacter jejuni causes gastroenteritis in humans and is a major concern in food safety. Commercially prepared chicken meats are frequently contaminated with C. jejuni, which is closely associated with the diffusion of intestinal contents in poultry processing plants. Sodium hypochlorite (NaClO) is commonly used during chicken processing to prevent food poisoning; however, its antimicrobial activity is not effective in the organic-rich solutions. In this study, we investigated the potential of a new photo-disinfection system, UVA-LED, for the disinfection of C. jejuni-contaminated chicken surfaces. The data indicated that UVA irradiation significantly killed C. jejuni and that its killing ability was significantly facilitated in NaClO-treated chickens. Effective inactivation of C. jejuni was achieved using a combination of UVA and NaClO, even in the organic-rich condition. The results of this study show that synergistic disinfection using a combination of UVA and NaClO has potential beneficial effects in chicken processing systems.
Takashi Uebanso, Moeka Fukui, Chisato Naito, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : SLC16a6, mTORC1, and autophagy involves ketone body excretion in the intestinal cells, Biology, Vol.12, No.12, 1467, 2023.
(要約)
Ketone bodies serve several functions in the intestinal epithelium, such as stem cell maintenance, cell proliferation and differentiation, and cancer growth. Nevertheless, there is limited understanding of the mechanisms governing the regulation of intestinal ketone body concentration. In this study, we elucidated the factors responsible for ketone body production and excretion using shRNA-mediated or pharmacological inhibition of specific genes or functions in the intestinal cells. We revealed that a fasting-mimicked culture medium, which excluded glucose, pyruvate, and glutamine, augmented ketone body production and excretion in the Caco2 and HT29 colorectal cells. This effect was attenuated by glucose or glutamine supplementation. On the other hand, the inhibition of the mammalian target of rapamycin complex1 (mTORC1) recovered a fraction of the excreted ketone bodies. In addition, the pharmacological or shbeclin1-mediated inhibition of autophagy suppressed ketone body excretion. The knockdown of basigin, a transmembrane protein responsible for targeting monocarboxylate transporters (MCTs), such as MCT1 and MCT4, suppressed lactic acid and pyruvic acid excretion but increased ketone body excretion. Finally, we found that MCT7 (SLC16a6) knockdown suppressed ketone body excretion. Our findings indicate that the mTORC1-autophagy axis and MCT7 are potential targets to regulate ketone body excretion from the intestinal epithelium.
K. Shinoda, Kazuaki Mawatari, Ngan Thi Kim Bui, H. Hirakawa, K. Awamoto, M. Wakitani, M. Wakitani, T. Shinoda and Akira Takahashi : Development of novel far-UVC light source for high germicidal effects and low human health risk, 2023 IEEE Photonics Conference, IPC 2023 - Proceedings, 2023.
Shintaro Inoue, Takahito Watanabe, Taiki Hamaguchi, Yoshiyasu Ishimaru, Katsuyuki Miyawaki, Takeshi Nikawa, Akira Takahashi, Sumihare Noji and Taro Mito : Combinatorial expression of ebony and tan generates body color variation from nymph through adult stages in the cricket, Gryllus bimaculatus., PLoS ONE, Vol.18, No.5, 2023.
(要約)
Insect body colors and patterns change markedly during development in some species as they adapt to their surroundings. The contribution of melanin and sclerotin pigments, both of which are synthesized from dopamine, to cuticle tanning has been well studied. Nevertheless, little is known about how insects alter their body color patterns. To investigate this mechanism, the cricket Gryllus bimaculatus, whose body color patterns change during postembryonic development, was used as a model in this study. We focused on the ebony and tan genes, which encode enzymes that catalyze the synthesis and degradation, respectively, of the precursor of yellow sclerotin N-β-alanyl dopamine (NBAD). Expression of the G. bimaculatus (Gb) ebony and tan transcripts tended to be elevated just after hatching and the molting period. We found that dynamic alterations in the combined expression levels of Gb'ebony and Gb'tan correlated with the body color transition from the nymphal stages to the adult. The body color of Gb'ebony knockout mutants generated by CRISPR/Cas9 systemically darkened. Meanwhile, Gb'tan knockout mutants displayed a yellow color in certain areas and stages. The phenotypes of the Gb'ebony and Gb'tan mutants probably result from an over-production of melanin and yellow sclerotin NBAD, respectively. Overall, stage-specific body color patterns in the postembryonic stages of the cricket are governed by the combinatorial expression of Gb'ebony and Gb'tan. Our findings provide insights into the mechanism by which insects evolve adaptive body coloration at each developmental stage.
Shinta Aizawa, Takashi Uebanso, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effects of the loss of maternal gut microbiota before pregnancy on gut microbiota, food allergy susceptibility, and epigenetic modification on subsequent generations, Bioscience of Microbiota, Food and Health, Vol.42, No.3, 203-212, 2023.
(要約)
Maternal environments affect the health of offspring in later life. Changes in epigenetic modifications may partially explain this phenomenon. The gut microbiota is a critical environmental factor that influences epigenetic modifications of host immune cells and the development of food allergies. However, whether changes in the maternal gut microbiota affect the development of food allergies and related epigenetic modifications in subsequent generations remains unclear. Here, we investigated the effects of antibiotic treatment before pregnancy on the development of the gut microbiota, food allergies, and epigenetic modifications in F1 and F2 mice. We found that pre-conception antibiotic treatment affected the gut microbiota composition in F1 but not F2 offspring. F1 mice born to antibiotic-treated mothers had a lower proportion of butyric acid-producing bacteria and, consequently, a lower butyric acid concentration in their cecal contents. The methylation level in the DNA of intestinal lamina propria lymphocytes, food allergy susceptibility, and production of antigen-specific IgE in the F1 and F2 mice were not different between those born to control and antibiotic-treated mothers. In addition, F1 mice born to antibiotic-treated mothers showed increased fecal excretion related to the stress response in a novel environment. These results suggest that the maternal gut microbiota is effectively passed onto F1 offspring but has little effect on food allergy susceptibility or DNA methylation levels in offspring.
Kai Ishida, Takaaki Shimohata, Yuna Kanda, Quoc Anh Nguyen, Rumiko Masuda, Kohei Yamazaki, Takashi Uebanso, Kazuaki Mawatari, Takashige Kashimoto and Akira Takahashi : Characteristic Metabolic Changes in Skeletal Muscle Due to Vibrio vulnificus Infection in a Wound Infection Model., mSystems, Vol.8, No.2, 2023.
(要約)
V. vulnificus causes necrotizing skin and soft tissue infections (NSSTIs) in severe cases, with high mortality and sign of rapid deterioration. Despite the severity of the infection, the dysfunction of the host metabolism in skeletal muscle triggered by V. vulnificus is poorly understood. In this study, by using a mouse wound infection model, we revealed characteristic changes in muscle catabolism and energy metabolism in skeletal muscle associated with bacterial proliferation in the infected tissues. Understanding such metabolic changes in V. vulnificus-infected tissue may provide crucial information to identify the mechanism via which V. vulnificus induces severe infections. Moreover, our metabolite data may be useful for the recognition, identification, or detection of V. vulnificus infections in clinical studies.
Kazuaki Mawatari, Nobuya Koike, Kazunari Nohara, Marvin Wirianto, Takashi Uebanso, Takaaki Shimohata, Yasuhiro Shikishima, Hiroyuki Miura, Yoshitaka Nii, J Mark Burish, Kazuhiro Yagita, Akira Takahashi, Seung-Hee Yoo and Zheng Chen : The Polymethoxyflavone Sudachitin Modulates the Circadian Clock and Improves Liver Physiology., Molecular Nutrition & Food Research, Vol.67, No.9, 2023.
(要約)
This study elucidates Sudachitin as a new clock-modulating PMF with beneficial effects to improve diurnal metabolic homeostasis and liver physiology, suggesting the circadian clock as a fundamental mechanism to safeguard physiological well-being.
Kazuya Tanifuji, Yuji Shiozaki, Megumi Koike, Minori Uga, Aoi Komiya, Mizuki Miura, Ayami Higashi, Takaaki Shimohata, Akira Takahashi, Noriko Ishizuka, Hisayoshi Hayashi, Yasuhiro Ichida, Shuichi Ohtomo, Naoshi Horiba, Ken-ichi Miyamoto and Hiroko Segawa : Effects of EOS789, a novel pan-phosphate transporter inhibitor, on phosphate metabolism : Comparison with a conventional phosphate binder, The Journal of Medical Investigation : JMI, Vol.70, No.1,2, 260-270, 2023.
(要約)
Inorganic phosphate (Pi) binders are the only pharmacologic treatment approved for hyperphosphatemia. However, Pi binders induce the expression of intestinal Pi transporters and have limited effects on the inhibition of Pi transport. EOS789, a novel pan-Pi transporter inhibitor, reportedly has potent efficacy in treating hyperphosphatemia. We investigated the properties of EOS789 with comparison to a conventional Pi binder. Protein and mRNA expression levels of Pi transporters were measured in intestinal and kidney tissues from male Wistar rats fed diets supplemented with EOS789 or lanthanum carbonate (LC). 32Pi permeability was measured in intestinal tissues from normal rats using a chamber. Increased protein levels of NaPi-2b, an intestinal Pi transporter, and luminal Pi removal were observed in rats treated with LC but not in rats treated with EOS789. EOS789 but not LC suppressed intestinal protein levels of the Pi transporter Pit-1 and sodium/hydrogen exchanger isoform 3. 32Pi flux experiments using small intestine tissues from rats demonstrated that EOS789 may affect transcellular Pi transport in addition to paracellular Pi transport. EOS789 has differing regulatory effects on Pi metabolism compared to LC. The properties of EOS789 may compensate for the limitations of LC therapy. The combined or selective use of EOS789 and conventional Pi binders may allow tighter control of hyperphosphatemia. J. Med. Invest. 70 : 260-270, February, 2023.
(キーワード)
Rats / Male / Animals / Phosphate Transport Proteins / Rats, Wistar / Hyperphosphatemia / Intestinal Absorption / Phosphates
Aya Tentaku, Shusaku Kurisu, Kurumi Sejima, Toshiki Nagao, Akira Takahashi and Shigenobu Yonemura : Proximal deposition of collagen IV by fibroblasts contributes to basement membrane formation by colon epithelial cells invitro., The FEBS Journal, Vol.289, No.23, 7466-7485, 2022.
(要約)
The basement membrane (BM) underlying epithelial tissue is a thin layer of extracellular matrix that governs tissue integrity and function. Epithelial BMs are generally assembled using BM components secreted from two origins: epithelium and stroma. Although denovo BM formation involves self-assembly processes of large proteins, it remains unclear how stroma-derived macromolecules are transported and assembled, specifically in the BM region. In this study, we established an invitro co-culture model of BM formation in which DLD-1 human colon epithelial cells were cultured on top of collagen I gel containing human embryonic OUMS-36T-2 fibroblasts as stromal cells. A distinct feature of our system is represented by OUMS-36T-2 cells which are almost exclusively responsible for synthesis of collagen IV, a major BM component. Exploiting this advantage, we found that collagen IV incorporation was significantly impaired in culture conditions where OUMS-36T-2 cells were not allowed to directly contact DLD-1 cells. Soluble collagen IV, once diluted in the culture medium, did not accumulate in the BM region efficiently. Live imaging of fluorescently tagged collagen IV revealed that OUMS-36T-2 cells deposited collagen IV aggregates directly onto the basal surface of DLD-1 cells. Collectively, these results indicate a novel mode of collagen IV deposition in which fibroblasts proximal to epithelial cells exclusively contribute to collagen IV assembly during BM formation.
Tomoki Ozaki, Yuta Yoshino, Ayumi Tachibana, Hideaki Shimizu, Takaaki Mori, Tomohiko Nakayama, Kazuaki Mawatari, Shusuke Numata, Junichi Iga, Akira Takahashi, Tetsuro Ohmori and Shu-ichi Ueno : Metabolomic alterations in the blood plasma of older adults with mild cognitive impairment and Alzheimer's disease (from the Nakayama Study)., Scientific Reports, Vol.12, No.1, 15205, 2022.
(要約)
Alzheimer's disease (AD) is a progressive disease, and the number of AD patients is increasing every year as the population ages. One of the pathophysiological mechanisms of AD is thought to be the effect of metabolomic abnormalities. There have been several studies of metabolomic abnormalities of AD, and new biomarkers are being investigated. Metabolomic studies have been attracting attention, and the aim of this study was to identify metabolomic biomarkers associated with AD and mild cognitive impairment (MCI). Of the 927 participants in the Nakayama Study conducted in Iyo City, Ehime Prefecture, 106 were selected for this study as Control (n = 40), MCI (n = 26), and AD (n = 40) groups, matched by age and sex. Metabolomic comparisons were made across the three groups. Then, correlations between metabolites and clinical symptoms were examined. The blood mRNA levels of the ornithine metabolic enzymes were also measured. Of the plasma metabolites, significant differences were found in ornithine, uracil, and lysine. Ornithine was significantly decreased in the AD group compared to the Control and MCI groups (Control vs. AD: 97.2 vs. 77.4; P = 0.01, MCI vs. AD: 92.5 vs. 77.4; P = 0.02). Uracil and lysine were also significantly decreased in the AD group compared to the Control group (uracil, Control vs. AD: 272 vs. 235; P = 0.04, lysine, Control vs. AD: 208 vs. 176; P = 0.03). In the total sample, the MMSE score was significantly correlated with lysine, ornithine, thymine, and uracil. The Barthel index score was significantly correlated with lysine. The instrumental activities of daily living (IADL) score were significantly correlated with lysine, betaine, creatine, and thymine. In the ornithine metabolism pathway, the spermine synthase mRNA level was significantly decreased in AD. Ornithine was decreased, and mRNA expressions related to its metabolism were changed in the AD group compared to the Control and MCI groups, suggesting an association between abnormal ornithine metabolism and AD. Increased betaine and decreased methionine may also have the potential to serve as markers of higher IADL in elderly persons. Plasma metabolites may be useful for predicting the progression of AD.
Toshiharu Kamishikiryo, Go Okada, Eri Itai, Yoshikazu Masuda, Satoshi Yokoyama, Masahiro Takamura, Manabu Fuchikami, Atsuo Yoshino, Kazuaki Mawatari, Shusuke Numata, Akira Takahashi, Tetsuro Ohmori and Yasumasa Okamoto : Left DLPFC activity is associated with plasma kynurenine levels and can predict treatment response to escitalopram in major depressive disorder., Psychiatry and Clinical Neurosciences, Vol.76, No.8, 367-376, 2022.
(要約)
Blood metabolite levels and resting-state brain activity were measured in patients with moderate to severe depression (n = 65) before and after 6-8 weeks of treatment with escitalopram, and these were compared between Responders and Nonresponders to treatment. We then examined the relationship between blood metabolites and brain activity related to treatment responsiveness in patients and healthy controls (n = 36).
Shiho Fukushima, Takaaki Shimohata, Yuri Inoue, Junko Kido, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Recruitment of LC3 by Campylobacter jejuni to Bacterial Invasion Site on Host Cells via the Rac1-Mediated Signaling Pathway, Frontiers in Cellular and Infection Microbiology, Vol.12, 829682, 2022.
(要約)
Campylobacter jejuni is a leading cause of food-borne disease worldwide. The pathogenicity of C. jejuni is closely associated with the internalization process in host epithelial cells, which is related to a host immune response. Autophagy indicates a key role in the innate immune system of the host to exclude invasive pathogens. Most bacteria are captured by autophagosomes and degraded by autophagosome-lysosome fusion in host cells. However, several pathogens, such as Salmonella and Shigella, avoid and/or escape autophagic degradation to establish infection. But autophagy involvement as a host immune response to C. jejuni infection has not been clarified. This study revealed autophagy association in C. jejuni infection. During infection, C. jejuni activated the Rho family small GTPase Rac1 signaling pathway, which modulates actin remodeling and promotes the internalization of this pathogen. In this study, we found the LC3 contribution to C. jejuni invasion signaling via the Rac1 signaling pathway. Interestingly, during C. jejuni invasion, LC3 was recruited to bacterial entry site depending on Rac1 GTPase activation just at the early step of the infection. C. jejuni infection induced LC3-II conversion, and autophagy induction facilitated C. jejuni internalization. Also, autophagy inhibition attenuated C. jejuni invasion step. Moreover, Rac1 recruited LC3 to the cellular membrane, activating the invasion of C. jejuni. Altogether, our findings provide insights into the new function of LC3 in bacterial invasion. We found the interaction between the Rho family small GTPase, Rac1, and autophagy-associated protein, LC3.
Ngan Thi Kim Bui, Kazuaki Mawatari, Takahiro Emoto, Shiho Fukushima, Takaaki Shimohata, Takashi Uebanso, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : UV-LED irradiation reduces the infectivity of herpes simplex virus type 1 by targeting different viral components depending on the peak wavelength., Journal of Photochemistry and Photobiology B: Biology, Vol.228, 112410, 2022.
(要約)
Herpes simplex virus type 1 (HSV-1) is an enveloped virus that mainly infects humans. Given its high global prevalence, disinfection is critical for reducing the risk of infection. Ultraviolet-light-emitting diodes (UV-LEDs) are eco-friendly irradiating modules with different peak wavelengths, but the molecules degraded by UV-LED irradiation have not been clarified. To identify the target viral molecules of UV-LEDs, we exposed HSV-1 suspensions to UV-LED irradiation at wavelengths of 260-, 280-, 310-, and 365-nm and measured viral DNA, protein, and lipid damage and infectivity in host cells. All UV-LEDs substantially reduced by inhibiting host cell transcription, but 260- and 280-nm UV-LEDs had significantly stronger virucidal efficiency than 310- and 365-nm UV-LEDs. Meanwhile, 260- and 280-nm UV-LEDs induced the formation of viral DNA photoproducts and the degradation of viral proteins and some phosphoglycerolipid species. Unlike 260- and 280-nm UV-LEDs, 310- and 365-nm UV-LEDs decreased the viral protein levels, but they did not drastically change the levels of viral DNA photoproducts and lipophilic metabolites. These results suggest that UV-LEDs reduce the infectivity of HSV-1 by targeting different viral molecules based on the peak wavelength. These findings could facilitate the optimization of UV-LED irradiation for viral inactivation.
(キーワード)
Disinfection / Herpesvirus 1, Human / Humans / Ultraviolet Rays / Viral Structures / Virus Inactivation / Water Purification
Tsubasa Kondo, Takashi Uebanso, Natsuki Arao, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effect of T1R3 Taste Receptor Gene Deletion on Dextran Sulfate Sodium-Induced Colitis in Mice., Journal of Nutritional Science and Vitaminology, Vol.68, No.3, 204-212, 2022.
(要約)
Taste receptor type 1 member 3 (T1R3) recognize umami or sweet tastes and also contributes type 2 immunity and autophagy in small intestine and muscle cells, respectively. Since imbalance of type 1 and type 2 immunity and autophagy affect intestinal bowel disease (IBD), we hypothesized that T1R3 have a potential role in the incidence and progression of colitis. In the present study, we investigated whether genetic deletion of T1R3 impacted aggravation of DSS-induced colitis in mice. We found that T1R3-KO mice showed reduction in colon damage, including reduced inflammation and colon shrinking relative to those of WT mice following DSS treatment. mRNA expression of tight junction components, particularly claudin1 was significantly lower in T1R3-KO mice with trend to lower inflammation related gene mRNA expression in colon. Other parameters, such as response to microbial stimuli in splenic lymphocytes and peritoneal macrophages, gut microbiota composition, and expression of autophagy-related proteins, were similar between WT and KO mice. Together, these results indicated that deletion of T1R3 has a minor role in intestinal inflammation induced by DSS-induced acute colitis in mice.
Takashi Uebanso, Mai Suyama, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effect of Vitamin B2-Deficient Diet on Hydroxyproline- or Obesity-Induced Hyperoxaluria in Mice., Molecular Nutrition & Food Research, Vol.65, No.15, e2100226, 2021.
(要約)
Together these results suggest that VB2 restriction could be a new dietary approach to improve hyperoxaluria when endogenous production of oxalate is increased.
Hitomi Iba, Takaaki Shimohata, Junko Kido, Sho Hatayama, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Vibrio parahaemolyticus induces inflammation-associated fluid accumulation via activation of the cystic fibrosis transmembrane conductance regulator., The Journal of Medical Investigation : JMI, Vol.68, No.1.2, 59-70, 2021.
(要約)
Vibrio parahaemolyticus is a foodborne bacterium that causes acute gastroenteritis through the consumption of contaminated, raw, or undercooked seafood. Cystic fibrosis transmembrane conductance regulator (CFTR) is a well-characterized chloride channel that regulates several other ion channels and transporters to maintain water homeostasis in the gut lumen. Also, CFTR is a main target of bacterial infection-associated diarrhea. Hence, the aim of this study was to clarify the contribution of CFTR in V. parahaemolyticus-induced diarrhea in a mouse model of intestinal loop fluid accumulation, with CFTR inhibitors and a CFTR knockout model. The results indicated that CFTR plays a critical role in fluid accumulation in response to V. parahaemolyticus infection. We also investigated the inflammatory association in CFTR-mediated V. parahaemolyticus-induced fluid secretion with cyclooxygenase inhibitors and found that fluid accumulation was decreased by inhibition of cyclooxygenase 2 produced by neutrophils. These findings suggest that V. parahaemolyticus-inducing infiltration and activation of neutrophils also participated in CFTR mediated fluid secretion. This study reveals an important relationship between V. parahaemolyticus-induced diarrhea and inflammation in a mouse model. J. Med. Invest. 68 : 59-70, February, 2021.
Kensuke Horiyama, Takahiro Emoto, Takeyuki Haraguchi, Takashi Uebanso, Yuki Naito, Takuma Gyobu, Kenta Kanemoto, Junichi Inobe, Ayumi Sano, Masatake Akutagawa and Akira Takahashi : Bowel sound-based features to investigate the effect of coffee and soda on gastrointestinal motility, Biomedical Signal Processing and Control, Vol.66, 102425, 2021.
Toshiya Okahisa, Masahiro Sogabe, Tadahiko Nakagawa, Kumiko Tanaka, Tetsu Tomonari, Tatsuya Taniguchi, Akira Takahashi, Yohsuke Kinouchi, Junji Nishioka, Naoki Igata, Hiroaki Yanagawa, takatoshi Komatsu, Yoshiaki Ohnishi, Masashi Fukuhara, Masashi Ishikawa, Hiroshi Shibata, Hirohiko Shinomiya, Masahiko Nakasono, Fumiko Kishi, Keiko Komai, Yayoi Tatsuki, Toru Murashima, Yoshihiro Deguchi, Hiroshi Aramaki, Hideyuki Fukumitsu and Tetsuji Takayama : Development of a novel automatic ascites filtration and concentration equipment with multi-ring-type roller pump units for cell-free and concentrated ascites reinfusion therapy., Artificial Organs, Vol.44, No.8, 856-872, 2020.
(要約)
Cell-free and concentrated ascites reinfusion therapy (CART) is an effective therapy for refractory ascites. However, CART is difficult to perform as ascites filtration and concentration is a complicated procedure. Moreover, the procedure requires the constant assistance of a clinical engineer or/and the use of an expensive equipment for the multi-purpose blood processing. Therefore, we developed a CART specialized equipment (mobility CART [M-CART]) that could be used safely with various safety measures and automatic functions such as automatic washing of clogged filtration filter and self-regulation of the concentration ratio. Downsizing, lightning of the weight, and automatic processing in M-CART required the use of newly developed multi-ring-type roller pump units. This equipment was approved under Japanese regulations in 2018. In performing 41 sessions of CART (for malignant ascites, 22 sessions; and hepatic ascites, 19 sessions) using this equipment in 17 patients, no serious adverse event occurred. An average of 4494 g of ascites was collected and the total amount of ascites was processed in all the sessions without any trouble. The mean weight of the processed ascites was 560 g and the mean concentration ratio was 8.0. The ascites were processed at a flow rate of 50 mL/min. The mean ascites processing time was 112.5 minutes and a 106.5-minutes (95.2%) ascites processing was performed automatically. The operator responded to alarms or support information 3.2 times on average (3.1 minutes, 2.1% of ascites processing time). Human errors related to ascites processing were detected by M-CART at 0.4 times per session on average and were appropriately addressed by the operator. The frequencies of automatic washing of clogged filtration filter and self-regulation of the concentration ratio were 31.7% and 53.7%, respectively. The mean recovery rates (recovery dose) of protein, albumin, and immunoglobulin G were 72.9%, 72.9%, and 71.2% (65.9 g, 34.9 g, and 13.2 g), respectively. Steroids were administered in 92.7% of the sessions to prevent fever and the mean increase in body temperature was 0.53°C. M-CART is a compact and lightweight automatic CART specialized equipment that can safely and easily process a large quantity of ascites without the constant assistance of an operator.
Cell-free and concentrated ascites reinfusion therapy(CART)is an effective and safe therapy for patients with refractory ascites or pleural effusion. CART was initially indicated for cirrhotic ascites, and has come to be widely used for malignant ascites. Recently, cancer therapy that applies cancer cells obtained by filtration process is considered, and CART attracts attention as one of the important therapies to support future cancer therapy. However, the numbers of CART in Japan is not sufficient because the equipment for CART is high price and large. Additionally, the specialized medical staff such as clinical engineers is necessary for CART because of complicated operation. Therefore, we think that development of next-generation type equipment for CART that can be performed safely, easily, and reliably is necessary. We could develop the exclusive equipment for CART according to the project management by multifarious worker cooperation in five years.
Quoc Anh Nguyen, Takaaki Shimohata, Sho Hatayama, Aya Tentaku, Junko Kido, Huong Thi Mai Bui, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Type III Secretion Effector VopQ of Vibrio parahaemolyticus Modulates Central Carbon Metabolism in Epithelial Cells., mSphere, Vol.5, No.2, e00960--19, 2020.
Takashi Uebanso, Ayumi Yoshimoto, Shinta Aizawa, Maya Nakamura, Rumiko Masuda, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Glycolate is a Novel Marker of Vitamin B2 Deficiency Involved in Gut Microbe Metabolism in Mice., Nutrients, Vol.12, No.3, E736, 2020.
(要約)
(VB2) deficiency, and show that gut microbiota sense dietary VB2 deficiency and accumulate GA in response. The plasma GA concentration responded to reduced VB2 supply from both the gut microbiota and the diet. These results suggest that GA is a novel marker that can be used to assess whether or not the net supply of VB2 from dietary sources and gut microbiota is sufficient. We also found that gut microbiota can provide short-term compensation for host VB2 deficiency when dietary VB2 is withheld.
Maria Ulfa, Momoyo Azuma, Masami Satou, Takaaki Shimohata, Shiho Fukushima, Junko Kido, Mariko Nakamoto, Takashi Uebanso, Kazuaki Mawatari, Takahiro Emoto, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Inactivation of Extended-spectrum β-Lactamase (ESBL)-producing Escherichia Coli by UVA-LED Irradiation System., The Journal of Medical Investigation : JMI, Vol.67, No.1-2, 163-169, 2020.
(要約)
The prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing rapidly and spreading worldwide, particularly in Asia, compared to other regions. In the last ten years, in our hospital, in particular, there has been a < 30% increase. To prevent the spread of ESBL in hospitals and the community, the ultraviolet (UV) A-light-emitting diode (LED) irradiation device was used to inactivate ESBL-E. coli in human livestock and the environment. ESBL-E. coli and E. coli bacterial samples were collected from patients at Tokushima University Hospital (Tokushima City, Japan). The UVA-LED irradiation system had 365 nm single wavelength, and the current of the circuit was set to 0.23 or 0.50 A consistently. Results demonstrated that UVA-LED was useful for the inactivation of ESBL-E. coli and E. coli. The minimum energy dosage required to inactivate ESBL-E. coli and E. coli was 40.76 J/cm2 (45 min) in the first type of UVA-LED and 38.85 J/cm2 (5 min) in the second type. There were no significant differences between ESBL-E. coli and E. coli. The inactivation of ESBL-E. coli was dependent on energy. These findings suggest that UVA-LED with 365 nm single wavelength could be useful for surface decontamination in healthcare facilities. J. Med. Invest. 67 : 163-169, February, 2020.
Hiromichi Yumoto, Takashi Uebanso, Takaaki Shimohata and Akira Takahashi : Current understanding of the gut microflora in subjects with nutrition-associated metabolic disorder such as obesity and/or diabetes: Is there any relevance with oral microflora?, Current Oral Health Reports, Vol.6, No.2, 100-109, 2019.
Chronic care patients undergoing hemodialysis for treatment of end-stage renal failure experience higher rates of bloodstream-associated infection due to the patients' compromised immune system and management of the bloodstream through catheters. Staphylococcus species are acommon cause of hemodialysis catheterrelated bloodstream infections. We investigated environmental bacterial contamination of dialysis wards and contamination of hemodialysis devices to determine the source of bacteria for these infections. All bacterial samples were collected by the swab method and the agarose stamp method. And which bacterium were identified by BBL CRYSTAL Kit or 16s rRNA sequences. In our data, bacterial cell number of hemodialysis device was lower than environment of patient surrounds. But Staphylococcus spp. were found predominantly on the hemodialysis device (46.8%), especially on areas frequently touched by healthcare-workers (such as Touch screen). Among Staphylococcus spp., Staphylococcus epidermidis was most frequently observed (42.1% of Staphylococcus spp.), and more surprising, 48.2% of the Staphylococcus spp. indicated high resistance for methicillin. Our finding suggests that hemodialysis device highly contaminated with bloodstream infection associated bacteria. This study can be used as a source to assess the risk of contamination-related infection and to develop the cleaning system for the better prevention for bloodstream infections in patients with hemodialysis. J. Med. Invest. 66 : 148-152, February, 2019.
Campylobacter jejuni is a major cause of bacterial foodborne illness in humans worldwide. Bacterial entry into a host eukaryotic cell involves the initial steps of adherence and invasion, which generally activate several cell-signaling pathways that induce the activation of innate defense systems, which leads to the release of proinflammatory cytokines and induction of apoptosis. Recent studies have reported that the unfolded protein response (UPR), a system to clear unfolded proteins from the endoplasmic reticulum (ER), also participates in the activation of cellular defense mechanisms in response to bacterial infection. However, no study has yet investigated the role of UPR in C. jejuni infection. Hence, the aim of this study was to deduce the role of UPR signaling via induction of ER stress in the process of C. jejuni infection. The results suggest that C. jejuni infection suppresses global protein translation. Also, 12 h of C. jejuni infection induced activation of the eIF2α pathway and expression of the transcription factor CHOP. Interestingly, bacterial invasion was facilitated by knockdown of UPR-associated signaling factors and treatment with the ER stress inducers, thapsigargin and tunicamycin, decreased the invasive ability of C. jejuni. An investigation into the mechanism of UPR-mediated inhibition of C. jejuni invasion showed that UPR signaling did not affect bacterial adhesion to or survival in the host cells. Further, Salmonella Enteritidis or FITC-dextran intake were not regulated by UPR signaling. These results indicated that the effect of UPR on intracellular intake was specifically found in C. jejuni infection. These findings are the first to describe the role of UPR in C. jejuni infection and revealed the participation of a new signaling pathway in C. jejuni invasion. UPR signaling is involved in defense against the early step of C. jejuni invasion and thus presents a potential therapeutic target for the treatment of C. jejuni infection.
Sho Hatayama, Takaaki Shimohata, Sachie Amano, Junko Kido, Q Anh Nguyen, Yuri Sato, Yuna Kanda, Aya Tentaku, Shiho Fukushima, Mutsumi Nakahashi, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Invasion and Inflammatory Barrier Disruption Promoting Bacterial Invasion from Lateral Membrane in Polarized Intestinal Epithelial Cells., Frontiers in Cellular and Infection Microbiology, Vol.8, No.30, 2018.
(要約)
Campylobacter jejuni invasion is closely related to C. jejuni pathogenicity. The intestinal epithelium contains polarized epithelial cells that form tight junctions (TJs) to provide a physical barrier against bacterial invasion. Previous studies indicated that C. jejuni invasion of non-polarized cells involves several cellular features, including lipid rafts. However, the dynamics of C. jejuni invasion of polarized epithelial cells are not fully understood. Here we investigated the interaction between C. jejuni invasion and TJ formation to characterize the mechanism of C. jejuni invasion in polarized epithelial cells. In contrast to non-polarized epithelial cells, C. jejuni invasion was not affected by depletion of lipid rafts in polarized epithelial cells. However, depletion of lipid rafts significantly decreased C. jejuni invasion in TJ disrupted cells or basolateral infection and repair of cellular TJs suppressed lipid raft-mediated C. jejuni invasion in polarized epithelial cells. In addition, pro-inflammatory cytokine, TNF- treatment that induce TJ disruption promote C. jejuni invasion and lipid rafts depletion significantly reduced C. jejuni invasion in TNF- treated cells. These data demonstrated that TJs prevent C. jejuni invasion from the lateral side of epithelial cells, where they play a main part in bacterial invasion and suggest that C. jejuni invasion could be increased in inflammatory condition. Therefore, maintenance of TJs integrity should be considered important in the development of novel therapies for C. jejuni infection.
Ayumi Yoshimoto, Takashi Uebanso, Mutsumi Nakahashi, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effect of prenatal administration of low dose antibiotics on gut microbiota and body fat composition of newborn mice., Journal of Clinical Biochemistry and Nutrition, Vol.62, No.2, 155-160, 2017.
(要約)
Several environmental factors during the prenatal period transgenerationally affect the health of newborns in later life. Because low-dose antibiotics have been used for promoting the growth of crops and livestock in agriculture, humans may have ingested residual antibiotics for several decades. However, the effect of prenatal administration of low-dose antibiotics on newborns' health in later life is unclear. In the present study, we found that prenatal treatment of murine mothers with low-dose antibiotics increased the abundance of bacteria of the phylum Firmicutes and the genera Clostridium IV and XIVa in feces from pups. In addition, the body fat percentage of mice in the antibiotic-treated group was higher than those in the control group at 12 weeks of age even though all pups were fed a standard diet. The body fat percentage of all mice was correlated with the abundance of fecal bacteria of Clostridium IV and XIVa. These results predict that low-dose antibiotic administration during the prenatal period affects the gut microbiota of newborns and possibly their health in later life.
Junko Kido, Takaaki Shimohata, Sachie Amano, Syo Hatayama, Quoc Anh Nguyen, Yuri Sato, Yuna Kanda, Aya Tentaku, Shiho Fukushima, Mutsumi Nakahashi, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : CFTR reduces microtubule-dependent Campylobacter jejuni invasion., Infection and Immunity, 2017.
(要約)
Campylobacter jejuni (C. jejuni) is gastroenteritis inducible food-born pathogen. Invasion and adhesion process are essential for leading gastroenteritis in C. jejuni infection process. As against bacterial strategy for efficacy invasion and adhesion, mucosal layer play a key role in defense systems, which modulated by several ion channels and transporters mediated water flux on the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) play the main role in waterfulux in intestine, and it closely related with bacterial clearance. We previously reported that C. jejuni infection suppresses CFTR channel activity in intestinal epithelial cells, however the mechanism and importance of this suppression is unclear. This study seeks to elucidate the role of CFTR in C. jejuni-infection. Using HEK293 cells that stably express wild type and mutated CFTR, we found that CFTR attenuated C. jejuni invasion, it was not involved bacterial adhesion or intracellular survival but associated with microtubule-dependent cellular transport. Moreover we revealed that CFTR attenuated function of microtubule motor protein but not microtubule stability, which causes inhibition of C. jejuni-invasion. Meanwhile, the CFTR mutant G551D-CFTR, which has defects in channel activity, suppressed C. jejuni-invasion, whereasF508-CFTR, which has defects in maturation, did not suppress, suggesting that CFTR suppression of C. jejuni-invasion is related to CFTR maturation but not channel activity.Taken together, mature CFTR inhibited C. jejuni invasion by regulating microtubule-mediated pathways. We suggest that CFTR plays a critical role in cellular defenses against C. jejuni-invasion, and CFTR suppression may be an initial step in promoting cellular invasion during C. jejuni-infection.
Takashi Uebanso, Saki Kano, Ayumi Yoshimoto, Chisato Naito, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effects of Consuming Xylitol on Gut Microbiota and Lipid Metabolism in Mice., Nutrients, Vol.9, No.7, 756, 2017.
(要約)
The sugar alcohol xylitol inhibits the growth of some bacterial species including Streptococcus mutans. It is used as a food additive to prevent caries. We previously showed that 1.5-4.0 g/kg body weight/day xylitol as part of a high-fat diet (HFD) improved lipid metabolism in rats. However, the effects of lower daily doses of dietary xylitol on gut microbiota and lipid metabolism are unclear. We examined the effect of 40 and 200 mg/kg body weight/day xylitol intake on gut microbiota and lipid metabolism in mice. Bacterial compositions were characterized by denaturing gradient gel electrophoresis and targeted real-time PCR. Luminal metabolites were determined by capillary electrophoresis electrospray ionization time-of-flight mass spectrometry. Plasma lipid parameters and glucose tolerance were examined. Dietary supplementation with low- or medium-dose xylitol (40 or 194 mg/kg body weight/day, respectively) significantly altered the fecal microbiota composition in mice. Relative to mice not fed xylitol, the addition of medium-dose xylitol to a regular and HFD in experimental mice reduced the abundance of fecal Bacteroidetes phylum and the genus Barnesiella, whereas the abundance of Firmicutes phylum and the genus Prevotella was increased in mice fed an HFD with medium-dose dietary xylitol. Body composition, hepatic and serum lipid parameters, oral glucose tolerance, and luminal metabolites were unaffected by xylitol consumption. In mice, 40 and 194 mg/kg body weight/day xylitol in the diet induced gradual changes in gut microbiota but not in lipid metabolism.
Takashi Uebanso, Ai Ohnishi, Reiko Kitayama, Ayumi Yoshimoto, Mutsumi Nakahashi, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Effects of Low-Dose Non-Caloric Sweetener Consumption on Gut Microbiota in Mice., Nutrients, Vol.9, No.6, 2017.
(要約)
Abstract: Non-caloric artificial sweeteners (NASs) provide sweet tastes to food without adding calories or glucose. NASs can be used as alternative sweeteners for controlling blood glucose levels and weight gain. Although the consumption of NASs has increased over the past decade in Japan and other countries, whether these sweeteners affect the composition of the gut microbiome is unclear. In the present study, we examined the effects of sucralose or acesulfame-K ingestion (at most the maximum acceptable daily intake (ADI) levels, 15 mg/kg body weight) on the gut microbiome in mice. Consumption of sucralose, but not acesulfame-K, for 8 weeks reduced the relative amount of Clostridiumcluster XIVa in feces. Meanwhile, sucralose and acesulfame-K did not increase food intake, body weight gain or liver weight, or fat in the epididymis or cecum. Only sucralose intake increased the concentration of hepatic cholesterol and cholic acid. Moreover, the relative concentration of butyrate and the ratio of secondary/primary bile acids in luminal metabolites increased with sucralose consumption in a dose-dependent manner. These results suggest that daily intake of maximum ADI levels of sucralose, but not acesulfame-K, affected the relative amount of the Clostridium cluster XIVa in fecal microbiome and cholesterol bile acid metabolism in mice.
Yanfei Hou, Mutsumi Nakahashi, Kazuaki Mawatari, Takaaki Shimohata, Takashi Uebanso, Yumi Harada, Akari Tsunedomi, Takahiro Emoto, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Combined treatment of UVA irradiation and antibiotics induces greater bactericidal effects on Vibrio parahaemolyticus., The Journal of Medical Investigation : JMI, Vol.63, No.1-2, 63-67, 2016.
(要約)
The presence of antibiotics in the environment and their subsequent impact on the development of multi-antibiotic resistant bacteria has raised concerns globally. Consequently, much research is focused on a method to produce a better disinfectant. We have established a disinfectant system using UVA-LED that inactivates pathogenic bacteria. We assessed the bactericidal efficiency of a combination of UVA-LED and antibiotics against Vibrio parahaemolyticus. Combined use of antibiotic drugs and UVA irradiation was more bactericidal than UVA irradiation or antibacterial drugs alone. The bactericidal synergy was observed at low concentrations of each drug that are normally unable to kill the bacteria. This combination has the potential to become a sterilization technology. J. Med. Invest. 63: 63-67, February, 2016.
Quang Ngoc Phan, Takashi Uebanso, Takaaki Shimohata, Mutsumi Nakahashi, Kazuaki Mawatari and Akira Takahashi : DNA-binding protein HU coordinates pathogenicity in Vibrio parahaemolyticus., Journal of Bacteriology, 2015.
(要約)
Nucleoid binding protein HU regulate cellular behaviors, including nucleoid structuring, general recombination, transposition, growth, replication, motility, metabolism, and virulence. It is concerned that both number of bacteria and number of virulence factors may affect pathogenecity of bacteria. In the present study, we investigated that which factor have dominant role during infection in one of the most rapidly growing bacteria Vibrio parahaemolyticus. We found that V. parahaemolyticus cytotoxicity is regulated, in a growth rate-independent manner, by the HU proteins through regulation of number of virulence factors including T3SS1 gene expression.
Toshitaka Ikehara, Mutsumi Nakahashi, Zehong Su, Masatake Akutagawa, Koichiro Tsuchiya, Mitsuo Kitamura, Akira Takahashi and Yohsuke Kinouchi : Effects of UV-A LED light irradiation on growth of cultured RAW 264.7 cells, Toxicological and Environmental Chemistry, Vol.97, No.2, 243-255, 2015.
(キーワード)
365 nm / LED light / 活性酸素 (reactive oxygen species) / Raw 264.7 cells / scavenger
Y Kadomura-Ishikawa, Katsuyuki Miyawaki, Akira Takahashi, Toshiya Masuda and Sumihare Noji : Light and abscisic acid independently regulated FaMYB10 in Fragaria x ananassa fruit, Planta, Vol.241, No.4, 953-965, 2015.
(要約)
Light and ABA independently regulated anthocyanin biosynthesis via activation of FaMYB10 expression. FaMYB10 accelerated anthocyanin synthesis of pelargonidin 3-glucoside and cyanidin 3-glucoside during strawberry fruit ripening. Light is an integral factor in fruit ripening. Ripening in non-climacteric fruit is also effected by the plant hormone abscisic acid (ABA). However, how light and/or ABA regulate fruit ripening processes, such as strawberry color development remains elusive. Results of the present study showed light and ABA regulated strawberry fruit coloration via activation of FaMYB10 expression, an R2R3 MYB transcription factor. Light exposure increased FaMYB10 transcript levels, flavonoid pathway genes, and anthocyanin content. Exogenous ABA promoted FaMYB10 expression, and anthocyanin content, accompanied by increased ABA-responsive transcript levels and flavonoid pathway genes. ABA biosynthesis inhibitor treatment, and RNAi-mediated down-regulation of the ABA biosynthetic gene (9-cis epoxycarotenoid dioxygenase: FaNCED1), and ABA receptor (magnesium chelatase H subunit: FaCHLH/ABAR) showed inverse ABA effects. Furthermore, additive effects were observed in anthocyanin accumulation under combined light and ABA, indicating independent light and ABA signaling pathways. FaMYB10 down-regulation by Agrobacterium-mediated RNA interference (RNAi) in strawberry fruits showed decreased pelargonidin 3-glucoside and cyanidin 3-glucoside levels, accompanied by consistent flavonoid pathway gene expression levels. FaMYB10 over-expression showed opposite FaMYB10 RNAi phenotypes, particularly cyanidin 3-glucoside synthesis by FaMYB10, which was correlated with FaF3'H transcript levels. These data provided evidence that light and ABA promoted FaMYB10 expression, resulting in anthocyanin accumulation via acceleration of flavonoid pathway gene expression. Finally, our results suggested FaMYB10 serves a role as a signal transduction mediator from light and ABA perception to anthocyanin synthesis in strawberry fruit.
Sachie Negoro, Takaaki Shimohata, Syo Hatayama, Yuri Sato, Mari Matsumoto, Hitomi Iba, Mutsumi Aihara, Takashi Uebanso, Yasuhiro Hamada, Yoshikazu Nishikawa, Shinji Yamasaki, Kazuaki Mawatari and Akira Takahashi : Campylobacter jejuni infection suppressed Cl(-) secretion induced by CFTR activation in T-84 cells., Journal of Infection and Chemotherapy, Vol.20, No.11, 682-688, 2014.
(要約)
Campylobacter jejuni causes foodborne disease associated with abdominal pain, gastroenteritis, and diarrhea. These symptoms are induced by bacterial adherence and invasion of host epithelial cells. C. jejuni infection can occur with a low infective dose, suggesting that C. jejuni may have evolved strategies to cope with the bacterial clearance system in the gastrointestinal tract. The mucosa layer is the first line of defense against bacteria. Mucus conditions are maintained by water and anion (especially Cl(-)) movement. Cystic fibrosis transmembrane conductance regulator (CFTR) is the main Cl(-) channel transporting Cl(-) to the lumen. Mutations in CFTR result in dehydrated secreted mucus and bacterial accumulation in the lungs, and recent studies suggest that closely related pathogenic bacteria also may survive in the intestine. However, the relationship between C. jejuni infection and CFTR has been little studied. Here, we used an (125)I(-) efflux assay and measurement of short-circuit current to measure Cl(-) secretion in C. jejuni-infected T-84 human intestinal epithelial cells. The basic state of Cl(-) secretion was unchanged by C. jejuni infection, but CFTR activator was observed to induce Cl(-) secretion suppressed in C. jejuni-infected T-84 cells. The suppression of activated Cl(-) secretion was bacterial dose-dependent and duration-dependent. A similar result was observed during infection with other C. jejuni strains. The mechanism of suppression may occur by affecting water movement or mucus condition in the intestinal tract. A failure of mucus barrier function may promote bacterial adhesion or invasion of host intestinal epithelial cells, thereby causing bacterial preservation in the host intestinal tract.
Mutsumi Nakahashi, Kazuaki Mawatari, Akiko Hirata, Miki Maetani, Takaaki Shimohata, Takashi Uebanso, Yasuhiro Hamada, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Simultaneous irradiation with different wavelengths of ultraviolet light has synergistic bactericidal effect on Vibrio parahaemolyticus., Photochemistry and Photobiology, Vol.90, No.6, 1397-1403, 2014.
(要約)
Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320-400 nm), UVB (280-320 nm), and UVC (< 280 nm). We previously developed UVA sterilization equipment with a UVA-light emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA-LED and another UV wavelength. An oxidative DNA product, 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased after irradiation by UVA-LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA-LED and UVC induced additional bactericidal effects, simultaneous irradiation with UVA-LED and UVC induced bactericidal synergistic effects. 8-OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response-deficient mutants, such as the recA and lexA strains. Because recA- and lexA-mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on suppression of the CPDs repair. The simultaneous irradiation of UVA-LED and UVC is a candidate new procedure for effective water disinfection. This article is protected by copyright. All rights reserved.
Kazuaki Mawatari, Emiko Yoshioka, Satomi Toda, Sonoko Yasui, Hiroko Furukawa, Takaaki Shimohata, Takamasa Ohnishi, Masaki Morishima, Nagakatsu Harada, Akira Takahashi, Hiroshi Sakaue and Yutaka Nakaya : Enhancement of endothelial function inhibits left atrial thrombi development in an animal model of spontaneous left atrial thrombosis., Circulation Journal, Vol.78, No.8, 1980-1988, 2014.
(要約)
Left atrial (LA) thrombosis is an important cause of systemic embolization. The SPORTS rat model of LA thrombi (Spontaneously-Running Tokushima-Shikoku), which have a unique characteristic of high voluntary wheel running, was previously established. The aim of the present study was to investigate how SPORTS rats develop LA thrombi.Methods and Results:Nitric oxide (NO) produced from cardiovascular endothelial cells plays an important protective role in the local regulation of blood flow, vascular tone, and platelet aggregation. No evidence of atrial fibrillation or hypercoagulability in SPORTS rats regardless of age was found; however, SPORTS rats demonstrated endothelial dysfunction and a decrease of NO production from a young age. In addition, endothelial NO synthase activity was significantly decreased in the LA and thoracic aorta endothelia of SPORTS rats. While voluntary wheel running was able to intermittently increase NO levels, running did not statistically decrease the incidence of LA thrombi at autopsy. However, L-arginine treatment significantly increased NO production and provided protection from the development of LA thrombi in SPORTS rats. They present study results indicate that NO has an important role in the development of LA thrombus, and endothelia pathways could provide new targets of therapy to prevent LA thrombosis. (Circ J 2014; 78: 1980-1988).
Akihiro Shirai, Mutsumi Aihara, Akira Takahashi, Hideaki Maseda and Takeshi Omasa : Synergistic antimicrobial activity based on the combined use of a gemini-quaternary ammonium compound and ultraviolet A light, Journal of Photochemistry and Photobiology B: Biology, Vol.130, 226-233, 2014.
(要約)
This study examined the utility of synergistic disinfection employing a gemini-quaternary ammonium salt (a gemini-QUAT, namely 3,3'-(2,7-dioxaoctane)bis(1-decylpyridinium bromide)), as an organic biocide in combination with irradiation by an ultraviolet-A (UV-A) light-emitting diode (LED) with a peak wavelength of 365nm. The combined system represents a novel disinfection method utilizing facilitated in situ oxidation depending on overproduction of reactive oxygen species (ROS) triggered by the initial action of the gemini-QUAT on the bacterial membrane. We demonstrate that this combination decreased the viability of pathogenic bacteria in a significant and rapid manner, and depended on doses of the gemini-QUAT and the fluence: the viability of Escherichia coli was reduced by greater than 5.0-logs by the combination procedure, but the decrease in viability was only 2.3-logs for exposure to UV at the same fluence dose in the absence of the gemini-QUAT. Adding catalase as a radical scavenger decreased bacterial inactivation by the combined disinfection procedure. Flow cytometric analysis indicated superoxide and hydrogen peroxide overproduction within cells treated with the combined disinfection procedure. The excessive superoxide, detected only in the combined system, appeared to be generated by the action of the gemini-QUAT at the bacterial membrane, leading to excessive and rapid generation of ROS in the system. Our data strongly suggested that this ROS promoted bacterial membrane peroxidation during initial treatment by the combination method, resulting in increased oxidative modification of DNA. These oxidative reactions may play an important role in the efficacy of this disinfection procedure.
Mutsumi Aihara, Xin Lian, Takaaki Shimohata, Takashi Uebanso, Kazuaki Mawatari, Yumi Harada, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Vegetable surface sterilization system using UVA light-emitting diodes., The Journal of Medical Investigation : JMI, Vol.61, No.3-4, 285-290, 2014.
(要約)
Surface sterilization of fresh produce has been needed in the food manufacturing/processing industry. Here we report a UVA-LED (Ultra Violet A-Light Emitting Diode) system for surface sterilization that is safe, efficacious, low cost, and apparently harmless to fresh produce. To test the system, Escherichia coli strain DH5 was spot-inoculated onto vegetable tissues, and treated under UVA-LED. Tissues were homogenized and bacteria quantified by colony-forming assay. Possible effects of UVA-LED on vegetable quality were evaluated by HPLC. Tissue weight changes were checked after treatment at 4, 15, and 30. Bacterial inactivation by UVA-LED radiation was observed after a 10 min treatment and increased with increasing time of irradiation. The log survival ratio reached -3.23 after a 90 min treatment. Bacterial cells surviving treatment grew slowly compared to non-irradiated control cells. Cabbage tissue lost weight over time after treatment, and weight loss increased with increasing incubation temperature, but there was no difference between losses by UVA-LED treated and control tissues at any temperature tested. In addition, no differences of Vitamin C content in cabbage tissue were detected by HPLC after UVA-LED treatment. These results suggest that UVA-LED treatment has great potential for vegetable surface sterilization in the food manufacturing/processing industry.
Y Kadomura-Ishikawa, Katsuyuki Miyawaki, Sumihare Noji and Akira Takahashi : Phototropin 2 is involved in blue light-induced anthocyanin accumulation in Fragaria x ananassa fruits, Journal of Plant Research, Vol.126, No.6, 847-857, 2013.
(要約)
Anthocyanins are widespread, essential secondary metabolites in higher plants during color development in certain flowers and fruits. In strawberries, anthocyanins are also key contributors to fruit antioxidant capacity and nutritional value. However, the effects of different light qualities on anthocyanin accumulation in strawberry (Fragaria x ananassa, cv. Sachinoka) fruits remain elusive. In the present study, we showed the most efficient increase in anthocyanin content occurred by blue light irradiation. Light sensing at the molecular level was investigated by isolation of two phototropin (FaPHOT1 and FaPHOT2), two cryptochrome (FaCRY1 and FaCRY2), and two phytochrome (FaPHYA and FaPHYB) homologs. Expression analysis revealed only FaPHOT2 transcripts markedly increased depending on fruit developmental stage, and a corresponding increase in anthocyanin content was detected. FaPHOT2 knockdown resulted in decreased anthocyanin content; however, overexpression increased anthocyanin content. These findings suggested blue light induced anthocyanin accumulation, and FaPHOT2 may play a role in sensing blue light, and mediating anthocyanin biosynthesis in strawberry fruits. This is the first report to find a relationship between visible light sensing, and color development in strawberry fruits.
Takafumi Yakabe, Takaaki Shimohata and Akira Takahashi : Lactobacillus brevis KB290 enhances IL-8 secretion by Vibrio parahaemolyticus-infected Caco-2 cells., Journal of Microbiology and Biotechnology, Vol.23, No.1, 118-124, 2013.
(要約)
Vibrio parahaemolyticus in uncooked seafood causes acute gastroenteritis. The microorganism has two sets of type III secretion systems and two hemolysins. When it injects its effector proteins into a host cell via type III secretion system 1, one of the type III secretion systems induces secretion of interleukin (IL)-8, a proinflammatory chemokine, through the phosphorylation of ERK 1/2 and p38 MAPK. Although probiotics have beneficial effects on hosts and can help control some infectious diseases, there is little research on the efficacy of probiotics in V. parahaemolyticus infection. Here we pretreated V. parahaemolyticus-infected human intestinal epithelial cells with heat-killed Lactobacillus brevis KB290, a probiotic isolated from fermented vegetables (traditional Japanese pickles) and utilized as an ingredient of beverages and supplementary foods, and demonstrated its efficacy in enhancing IL-8 secretion from V. parahaemolyticus-infected cells. Among the three heat-killed lactic acid bacterial strains we tested, L. brevis KB290 induced the highest level of IL-8 secretions in the infected cells. Relative to control cells (Caco-2 cells pretreated with PBS), V. parahaemolyticus-infected Caco-2 cells pretreated with heat-killed L. brevis KB290 secreted IL-8 earlier, although concentrations were similar 450min after infection. Heat-killed L. brevis KB290 pretreatment also induced earlier ERK 1/2 phosphorylation, greater p38 MAPK phosphorylation, and enhanced IL-8 mRNA expression. Heat-killed L. brevis KB290 accelerated IL-8 secretion, a host cell immune response, in V. parahaemolyticus-infected cells. We consider this to be beneficial because IL-8 plays an important defensive role against infection, and would contribute to the repair of injured epithelial cells.
Atsushi Hashimoto, Kazuaki Mawatari, Yohsuke Kinouchi, Masatake Akutagawa, Naotomo Ota, Kazuyuki Nishimura, Tsuyoshi Hirata and Akira Takahashi : Inactivation of MS2 Phage and Cryptosporidium parvum Oocysts Using UV-A from High-Intensity Light-Emitting Diode for Water Disinfection, Journal of Water and Environment Technology, Vol.11, No.4, 299-307, 2013.
(要約)
In this study, high-intensity, UV-A (ranging from 360 to 370 nm, peak wavelength at 365 nm) produced by a light-emitting diode was used for the inactivation of MS2 phage and <I>Cryptosporidium parvum</I> oocyst. In the irradiation experiment with MS2 phage, approximately 44 and 65 J/cm<SUP>2</SUP> of UV-A were required to obtain -2 and -3 log inactivations, respectively. The -2 and -3 log inactivations of <I>Cryptosporidium</I> oocysts required 338 and 508 J/cm<SUP>2</SUP> UV-A, respectively, which were 7.7 - 7.8 times greater than those required for MS2 phage. The possibility that high-intensity UV-A irradiation can inactivate both protozoa and viruses (phage) was demonstrated in this study.
Takaaki Shimohata, Kazuaki Mawatari, Hitomi Iba, Masakazu Hamano, Sachie Negoro, Shoko Asada, Mutsumi Aihara, Akiko Hirata, Zehong Su and Akira Takahashi : VopB1 and VopD1 are essential for translocation of type III secretion system 1 effectors of Vibrio parahaemolyticus., Canadian Journal of Microbiology, Vol.58, No.8, 1002-1007, 2012.
(要約)
Vibrio parahaemolyticus is a pathogenic Vibrio species that causes food-borne acute gastroenteritis, often related to the consumption of raw or undercooked seafood. Vibrio parahaemolyticus has 2 type III secretion systems (T3SS1 and T3SS2). Here, we demonstrate that VP1657 (VopB1) and VP1656 (VopD1), which share sequence similarity with Pseudomonas genes popB (38%) and popD (36%), respectively, are essential for translocation of T3SS1 effectors into host cells. A VP1680CyaA fusion reporter system was constructed to observe effector translocation. Using this reporter assay we showed that the VopB1 and VopD1 deletion strains were unable to translocate VP1680 to host cell but that the secretion of VP1680 into the culture medium was not affected. VopB1 or VopD1 deletion strains did not enhance cytotoxicity and failed to activate mitogen-activated protein kinases and secretion of interleukin-8, which depend on VP1680. Thus, we conclude that VopB1 and VopD1 are essential components of the translocon. To target VopB1 and VopD1 may have therapeutic potential for the treatment or prevention in V. parahaemolyticus infection.
Thanh Tam Thi Le, Kazuaki Mawatari, Miki Maetani, Tomomi Yamamoto, Sayaka Hayashida, Hitomi Iba, Mutsumi Aihara, Akiko Hirata, Takaaki Shimohata, Takashi Uebanso and Akira Takahashi : VP2118 has major roles in Vibrio parahaemolyticus response to oxidative stress., Biochimica et Biophysica Acta (BBA) - General Subjects, Vol.1820, No.10, 1686-1692, 2012.
(要約)
The V. parahaemolyticus FeSOD VP2118 may enhance ROS resistance and could promote its survival in the intestinal tract to facilitate host tissue infection.
Tuyet Le Thi Nhung, Hirofumi Nagata, Akira Takahashi, Mutsumi Aihara, Toshihiro Okamoto, Takaaki Shimohata, Kazuaki Mawatari, Masatake Akutagawa, Yohsuke Kinouchi and Masanobu Haraguchi : Sterilization effect of UV light on Bacillus spores using TiO(2) films depends on wavelength., The Journal of Medical Investigation : JMI, Vol.59, No.1-2, 53-58, 2012.
(要約)
UV light and photocatalysts such as titanium dioxide (TiO(2)) and silver (Ag) are useful for disinfection of water and surfaces. However, the effect of UV wavelength on photocatalytic disinfection of spores is not well understood. Inactivation of Bacillus spores has been examined using different UV wavelengths and TiO(2) or TiO(2)/Ag composite materials. The level of UVA disinfection of Bacillus anthracis and Bacillus brevis vegetative cells increased with the presence of the TiO(2) and Ag photocatalysts, but had little effect on their spores. B. brevis spores were slightly more sensitive to UVB and UVC than the spores of B. atrophaeus. Photocatalytic sterilization against spores was strongest in UVC and UVB and weakest in UVA. The rate of inactivation of Bacillus spores was significantly increased by the presence of TiO(2), but was not markedly different from that induced by the presence of Ag. Therefore, TiO(2)/Ag plus UVA can be used for the sterilization of vegetative cells, while TiO(2) and UVC are effective against spores.
Masayuki Nakano, Eiki Yamasaki, Akitoyo Ichinose, Takaaki Shimohata, Akira Takahashi, K Junko Akada, Kazuyuki Nakamura, Joel Moss, Toshiya Hirayama and Hisao Kurazono : Salmonella enterotoxin (Stn) regulates membrane composition and integrity., Disease Models & Mechanisms, Vol.5, No.4, 515-521, 2012.
(要約)
The mechanism of action of Salmonella enterotoxin (Stn) as a virulence factor in disease is controversial. Studies of Stn have indicated both positive and negative effects on Salmonella virulence. In this study, we attempted to evaluate Stn function and its effects on Salmonella virulence. To investigate Stn function, we first performed in vitro and in vivo analysis using mammalian cells and a murine ileal loop model. In these systems, we did not observe differences in virulence phenotypes between wild-type Salmonella and an stn gene-deleted mutant. We next characterized the phenotypes and molecular properties of the mutant strain under various in vitro conditions. The proteomic profiles of the total cell membrane protein fraction differed between wild type and mutant in that there was an absence of a protein in the mutant strain, which was identified as OmpA. By far-western blotting, OmpA was found to interact directly with Stn. To verify this result, the morphology of Salmonella was examined by transmission electron microscopy, with OmpA localization being analyzed by immunogold labeling. Compared with wild-type Salmonella, the mutant strain had a different pole structure and a thin periplasmic space; OmpA was not seen in the mutant. These results indicate that Stn, via regulation of OmpA membrane localization, functions in the maintenance of membrane composition and integrity.
Nakagawa Tadahiko, Nagakatsu Harada, Miyamoto Aiko, Kawanishi Yukiko, Yoshida Masaki, Masayuki Shono, Kazuaki Mawatari, Akira Takahashi, Hiroshi Sakaue and Yutaka Nakaya : Membrane topology of murine glycerol-3-phosphate acyltransferase 2., Biochemical and Biophysical Research Communications, Vol.418, No.3, 506-511, 2012.
(要約)
Glycerol-3-phosphate acyltransferase (GPAT) is a rate-limiting enzyme in mammalian triacylglycerol biosynthesis. GPAT is a target for the treatment of metabolic disorders associated with high lipid accumulation. Although the molecular basis for GPAT1 activation has been investigated extensively, the activation of other isoforms, such as GPAT2, is less well understood. Here the membrane topology of the GPAT2 protein was examined using an epitope-tag-based method. Exogenously expressed GPAT2 protein was present in the membrane fraction of transformed HEK293 cells even in the presence of Na(2)CO(3) (100 mM), indicating that GPAT2 is a membrane-bound protein. Trypsin treatment of the membrane fraction degraded the N-terminal (FLAG) and C-terminal (myc-epitope) protein tags of the GPAT2 protein. Bioinformatic analysis of the GPAT2 protein sequence indicated four hydrophobic sequences as potential membrane-spanning regions (TM1-TM4). Immunoblotting of the myc-epitope tag, which was inserted between each TM region of the GPAT2 protein, showed that the amino acid sequence between TM3 and TM4 was protected from trypsin digestion. These results suggest that the GPAT2 protein has two transmembrane segments and that the N-terminal and C-terminal regions of this protein face the cytoplasm. These results also suggest that the enzymatically active motifs I-III of the GPAT2 protein face the cytosol, while motif IV is within the membrane. It is expected that the use of this topological model of GPAT2 will be essential in efforts to elucidate the molecular mechanisms of GPAT2 activity in mammalian cells.
Sonoko Yasui, Kazuaki Mawatari, Ran Morizumi, Hiroko Furukawa, Takaaki Shimohata, Nagakatsu Harada, Akira Takahashi and Yutaka Nakaya : Hydrogen peroxide inhibits insulin-induced ATP-sensitive potassium channel activation independent of insulin signaling pathway in cultured vascular smooth muscle cells., The Journal of Medical Investigation : JMI, Vol.59, No.1-2, 36-44, 2012.
(要約)
Both reactive oxygen species (ROS) and insulin resistance have been reported to play essential pathophysiological roles in cardiovascular diseases, such as hypertension and atherosclerosis. However, the mechanistic link between ROS and insulin resistance in the vasculature remains unclear. Recently we have shown that insulin causes membrane hyperpolarization via ATP-sensitive potassium (K(ATP)) channel activation, which is mediated by phosphatidylinositol 3-kinase (PI3-K) in cultured vascular smooth muscle cells (VSMCs). K(ATP) channel in the vasculature is critical in the regulation of vascular tonus. Here we examined the effects of ROS induced by hydrogen peroxide (H(2)O(2)) on insulin-induced K(ATP) channel activities in cultured VSMCs, A10 cells. H(2)O(2) (10 µM) increased significantly intercellular ROS in A10 cells. By using a cell-attached patch clamp experiment, 10 µM H(2)O(2) suppressed significantly insulin-induced K(ATP) channel activation without inhibition of insulin receptor signal transduction component including IRS and Akt in A10 cells. Furthermore 10 µM H(2)O(2) suppressed significantly pinacidil-induced K(ATP) channel activation in A10 cells. These data suggest that H(2)O(2) might inhibit directly K(ATP) channel independent of insulin signaling pathway. This study may contribute to our understanding of mechanisms of insulin resistance-associated cardiovascular disease.
H Nazari, A Khaleghian, Akira Takahashi, N Harada, N J. G. Webster, M Nakano, K Kishi, Y Ebina and Y Nakaya : Cortactin, an Actin Binding Protein, Regulates GLUT4 Translocation via Actin Filament Remodeling, Biochemistry (Moscow), Vol.76, No.11, 1262-1269, 2011.
(要約)
Insulin regulates glucose uptake into fat and skeletal muscle cells by modulating the translocation of GLUT4 between the cell surface and interior. We investigated a role for cortactin, a cortical actin binding protein, in the actin filament organization and translocation of GLUT4 in Chinese hamster ovary (CHO-GLUT4myc) and L6-GLUT4myc myotube cells. Overexpression of wild-type cortactin enhanced insulin-stimulated GLUT4myc translocation but did not alter actin fiber formation. Conversely, cortactin mutants lacking the Src homology 3 (SH3) domain inhibited insulin-stimulated formation of actin stress fibers and GLUT4 translocation similar to the actin depolymerizing agent cytochalasin D. Wortmannin, genistein, and a PP1 analog completely blocked insulin-induced Akt phosphorylation, formation of actin stress fibers, and GLUT4 translocation indicating the involvement of both PI3-K/Akt and the Src family of kinases. The effect of these inhibitors was even more pronounced in the presence of overexpressed cortactin suggesting that the same pathways are involved. Knockdown of cortactin by siRNA did not inhibit insulin-induced Akt phosphorylation but completely inhibited actin stress fiber formation and glucose uptake. These results suggest that the actin binding protein cortactin is required for actin stress fiber formation in muscle cells and that this process is absolutely required for translocation of GLUT4-containing vesicles to the plasma membrane.
(キーワード)
Actin Cytoskeleton / Actins / Androstadienes / Animals / CHO Cells / Cell Membrane / Cortactin / Cricetinae / Cytochalasin D / Gene Knockdown Techniques / Glucose Transporter Type 4 / Humans / Insulin / Microfilament Proteins / Muscle Fibers, Skeletal / Phosphorylation / Protein Transport / Proto-Oncogene Proteins c-akt / RNA, Small Interfering / Signal Transduction / Stress Fibers / src-Family Kinases
Shinji Kawahito, Takashi Kawano, Hiroshi Kitahata, Jun Oto, Akira Takahashi, Kazumi Takaishi, Nagakatsu Harada, Tadahiko Nakagawa, Hiroyuki Kinoshita, Toshiharu Azma, Yutaka Nakaya and Shuzo Oshita : Molecular mechanisms of the inhibitory effects of clonidine on vascular adenosine triphosphate-sensitive potassium channels., Anesthesia & Analgesia, Vol.113, No.6, 1374-1380, 2011.
(要約)
We investigated the effects of the imidazoline-derived α2-adrenoceptor agonist clonidine on vascular adenosine triphosphate-sensitive potassium (K(ATP)) channel activity in rat vascular smooth muscle cells and recombinant vascular K(ATP) channels transiently expressed in COS-7 cells. Using the patch-clamp method, we investigated the effects of clonidine on the following: (1) native vascular K(ATP) channels; (2) recombinant K(ATP) channels with different combinations of various types of inwardly rectifying potassium channel (Kir6.0 family: Kir6.1, 6.2) and sulfonylurea receptor (SUR1, 2A, 2B) subunits; (3) SUR-deficient channels derived from a truncated isoform of the Kir6.2 subunit (Kir6.2ΔC36 channels); and (4) mutant Kir6.2ΔC36 channels with diminished sensitivity to ATP (Kir6.2ΔC36-K185Q channels). Clonidine (≥3 × 10(-8) M) inhibited native K(ATP) channel activity in cell-attached configurations with a half-maximal inhibitory concentration value of 1.21 × 10(-6) M and in inside-out configurations with a half-maximal inhibitory concentration value of 0.89 × 10(-6) M. With similar potency, clonidine (10(-6) or 10(-3) M) also inhibited the activities of various recombinant SUR/Kir6.0 K(ATP) channels, the Kir6.2ΔC36 channel, and the Kir6.2ΔC36-K185Q channel. Clinically relevant concentrations of clonidine inhibit K(ATP) channel activity in vascular smooth muscle cells. This inhibition seems to be the result of its effect on the Kir6.0 subunit and not on the SUR subunit.
Tuyet Nhung Thi Le, Hirofumi Nagata, Mutsumi Aihara, Akira Takahashi, Toshihiro Okamoto, Takaaki Shimohata, Kazuaki Mawatari, Yhosuke Kinouchi, Masatake Akutagawa and Masanobu Haraguchi : Additional effects of silver nanoparticles on bactericidal efficiency depend on calcination temperature and dip-coating speed., Applied and Environmental Microbiology, Vol.77, No.16, 5629-5634, 2011.
(要約)
There is an increasing interest in the application of photocatalytic properties for disinfection of surfaces, air, and water. Titanium dioxide is widely used as a photocatalyst, and the addition of silver reportedly enhances its bactericidal action. However, the synergy of silver nanoparticles and TiO(2) is not well understood. The photocatalytic elimination of Bacillus atrophaeus was examined under different calcination temperatures, dip-coating speeds, and ratios of TiO(2), SiO(2), and Ag to identify optimal production conditions for the production of TiO(2)- and/or TiO(2)/Ag-coated glass for surface disinfection. Photocatalytic disinfection of pure TiO(2) or TiO(2) plus Ag nanoparticles was dependent primarily on the calcination temperature. The antibacterial activity of TiO(2) films was optimal with a high dip-coating speed and high calcination temperature (600°C). Maximal bacterial inactivation using TiO(2)/Ag-coated glass was also observed following high-speed dip coating but with a low calcination temperature (250°C). Scanning electron microscopy (SEM) showed that the Ag nanoparticles combined together at a high calcination temperature, leading to decreased antibacterial activity of TiO(2)/Ag films due to a smaller surface area of Ag nanoparticles. The presence of Ag enhanced the photocatalytic inactivation rate of TiO(2), producing a more pronounced effect with increasing levels of catalyst loading.
Hiroko Furukawa, Kazuaki Mawatari, Kei Koyama, Sonoko Yasui, Ran Morizumi, Takaaki Shimohata, Nagakatsu Harada, Akira Takahashi and Yutaka Nakaya : Telmisartan increases localization of glucose transporter 4 to the plasma membrane and increases glucose uptake via peroxisome proliferator-activated receptor γ in 3T3-L1 adipocytes., European Journal of Pharmacology, Vol.660, No.2-3, 485-491, 2011.
(要約)
Angiotensin II is a peptide hormone with strong vasoconstrictive action, and recent reports have shown that Angiotensin II receptor type 1 antagonists (angiotensin II receptor blockers) also improve glucose metabolism. The angiotensin II receptor blocker telmisartan acts as an agonistic ligand of the peroxisome proliferator-activated receptor gamma (PPARγ). In this study, we investigated the effects of telmisartan on glucose uptake and insulin sensitivity in 3T3-L1 adipocytes and compared it with the action of other angiotensin II receptor blockers. Telmisartan treatment dose-dependently increased (from 1 μM) protein expression of PPARγ-regulated molecules such as fatty acid binding protein 4 (FABP4), insulin receptor, and glucose transporter 4 (GLUT4). Telmisartan increased glucose uptake both with and without insulin stimulation in 3T3-L1 adipocytes. Telmisartan increased the up-regulation of phosphorylated insulin receptor, insulin receptor substrate-1 (IRS-1) and Akt by insulin, suggesting that telmisartan increases insulin sensitivity. Furthermore, in the absence of insulin, telmisartan, but not candesartan, increased GLUT4 levels at the plasma membrane. These effects by 10 μM telmisartan were similar potency to those of 1 μM troglitazone, an activator of PPARγ. In addition, up-regulation of glucose uptake by telmisartan was inhibited by a PPARγ antagonist, T0070907 (2-chloro-5-nitro-N-4-pyridinyl-benzamide). These results indicate that telmisartan acts via PPARγ activation in adipose tissue and may be an effective therapy for the metabolic syndrome.
(キーワード)
3T3-L1 Cells / Adipocytes / Angiotensin II Type 1 Receptor Blockers / Animals / Benzimidazoles / Benzoates / Cell Membrane / Fatty Acid-Binding Proteins / Glucose / Glucose Transporter Type 4 / Insulin / Mice / PPAR gamma / Protein Transport / Receptor, Insulin / Signal Transduction
Takaaki Shimohata, Masayuki Nakano, Xin Lian, Tomomi Shigeyama, Hitomi Iba, Akiko Hamamoto, Masaki Yoshida, Nagakatsu Harada, Hironori Yamamoto, Masayuki Yamato, Kazuaki Mawatari, Toshiaki Tamaki, Yutaka Nakaya and Akira Takahashi : Vibrio parahaemolyticus infection induces modulation of IL-8 secretion through dual pathway via VP1680 in Caco-2 cells., The Journal of Infectious Diseases, Vol.203, No.4, 537-544, 2011.
(要約)
Vibrio parahaemolyticus causes acute gastroenteritis and inflammations in humans. A variety of pathogenic bacteria can stimulate mitogen-activated protein kinases (MAPKs) in host cells. Phosphorylation of MAPKs leads to production of interleukin (IL)- 8 and subsequently causes inflammations. Thus, MAPK cascades were strong candidates for the main signaling pathway of V. parahaemolyticus-induced acute inflammation.
A Hamamoto, M Bandou, K Nakano, Kazuaki Mawatari, Nagakatsu Harada, Masatake Akutagawa, Yohsuke Kinouchi, Yutaka Nakaya and Akira Takahashi : Differences in stress response after UVC or UVA irradiation in Vibrio parahaemolyticus., Environmental Microbiology Reports, Vol.2, No.5, 660-666, 2010.
Takaaki Shimohata and Akira Takahashi : Diarrhea induced by infection of Vibrio parahaemolyticus., The Journal of Medical Investigation : JMI, Vol.57, No.3-4, 179-182, 2010.
(要約)
Vibrio parahaemolyticus is a human pathogen that naturally inhabits marine and estuarine environments. Infection with V. parahaemolyticus is often associated with the consumption of raw or undercooked seafood, causing gastroenteritis with watery diarrhea. The presence of two type III secretion system (T3SS) proteins, thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), has been closely associated with the severity of diarrheal illness. TDH and TRH have various biological activities including hemolytic activity, cardiotoxicity, and enterotoxicity. T3SS1 is involved in cytotoxicity to host cells and orchestrates a multifaceted host cell infection by induction of autophagy, cell rounding, and cell lysis. T3SS2 is thought to be related to the enterotoxicity of V. parahaemolyticus. The activities of inducing diarrhea of each of the virulence factors were summarized in this review.
Takashi Kawano, Katsuya Tanaka, hua Yin, Satoru Eguchi, Hiroaki Kawano, Akira Takahashi, Yutaka Nakaya and Shuzo Oshita : Effects of ketamine on nicorandil induced ATP-sensitive potassium channel activity in cell line derived from rat aortic smooth muscle., The Journal of Medical Investigation : JMI, Vol.57, No.3-4, 237-244, 2010.
(要約)
Nicorandil opens adenosine triphosphate-sensitive potassium (K(ATP)) channels in the cardiovascular system and is being increasingly used for the treatment of angina pectoris. In the present study, we tested whether intravenous anesthetic agent ketamine affected nicorandil-induced native vascular K(ATP) channel activation.
Ali Khaleghian, Gholam Hossein Riazi, Mahmoud Ghafari, Marzieh Rezaie, Akira Takahashi, Yutaka Nakaya and Hossain Nazari : Effect of inganen anticancer properties on microtobule organization., Pakistan Journal of Pharmaceutical Sciences, Vol.23, No.3, 273-278, 2010.
(要約)
Euphorbia tirucalli (Euphorbiaceae family) an environmental risk factor for Burkitt's lymphoma also has pharmacological activities. In the northeast of region in Brazil its latex is used as an antimicrobial, antiparasitic in the treatment of coughs, rheumatism, cancer and other disease as folk treatment. The prevalent constituents of this plant latex are diterpenes from the Inganen types (ingenol esters) as well as the tigliane (phorbol esters). Scientifically, there is not any data till now about anticancer effects of the Euphorbia tirucalli Linn., since the Ingenol esters have already presented tumor-promoting ability. Microtubules (MTs), and cytoskeletal proteins are essential in eukaryotic cells for a variety of functions, such as cellular transport, cell motility and mitosis. Single Inganen in cytoplasm can interact with these proteins and affect on their crucial functions. In this study, we showed the effects of Inganen on MT organization using ultraviolet spectrophotometer and fluorometry. The fluorescent spectroscopy showed a significant tubulin conformational change at the presence of Inganen which decrease polymerization of tubulin as well as the ultraviolet spectroscopy results. The aim of this study is to find the potential function of Inganen for treatment of cancer in cells and human organs.
Zehong Su, Masayuki Nakano, Tetsuro Koga, Xin Lian, Akiko Hamamoto, Takaaki Shimohata, Yumi Harada, Kazuaki Mawatari, Nagakatsu Harada, Masatake Akutagawa, Yutaka Nakaya and Akira Takahashi : Hfq regulates anti-oxidative ability in Vibrio parahaemolyticus., The Journal of General and Applied Microbiology, Vol.56, No.3, 181-186, 2010.
(要約)
Hfq plays a fundamental role in bacterial cell physiology. It can stimulate or repress the expression of certain target genes, and there is a possibility that Hfq regulates the oxidative stress response. However, how Hfq functions that in Vibrio parahaemolyticus remains speculative. In this paper, we explain the functions Hfq plays in V. parahaemolyticus in the gene expression of superoxide dismutase gene and catalase gene, comparing the hfq deletion mutant strain to the parental strain. The results show that the hfq deletion mutant V. parahaemolyticus has a stronger ability to resist H(2)O(2). Superoxide dismutase (SOD) and catalase (CAT) activities in the hfq deletion mutant were remarkably higher than in the parental strain. Genetic experiments indicated that the gene expression of sod and kat was up-regulated in the mutant strain. These results indicate that Hfq down-regulates CAT and SOD activity, and Hfq is associated with the oxidative stress response.
Xin Lian, Kayo Tetsutani, Akiko Hamamoto, Masayuki Nakano, Kazuaki Mawatari, Nagakatsu Harada, Masayuki Yamato, Masatake Akutagawa, Yohsuke Kinouchi, Yutaka Nakaya and Akira Takahashi : A new colored beverage disinfection system using UV-A light-emitting diodes, Biocontrol Science, Vol.15, No.1, 33-37, 2010.
(要約)
In this study we evaluated the ability of the UV-A-LED to eliminate bacteria in a colored beverage. Ten edible pigments were used to make a colored solution at concentrations of 1.0%, 0.1%, 0.01% and 0.001%. We used a colony-forming assay to monitor the bactericidal action against the bacteria. The bactericidal effect of UV-A-LED against Escherichia coli DH5 a decreased with the increasing concentration of almost all of the edible pigments. Although less effective in colored solutions and commercially available orange juice than in the positive control PBS, it holds potential for further development and use to ensure food and water safety.
Masaki Yoshida, Nagakatsu Harada, Keiko Yoshida, Tadahiko Nakagawa, Takaaki Shimohata, Kazuaki Mawatari, Akira Takahashi, Hiroshi Sakaue and Yutaka Nakaya : High density lipoprotein inhibits the activation of sterol regulatory element-binding protein-1 in cultured cells., FEBS Letters, Vol.584, No.6, 1217-1222, 2010.
(要約)
A link between cellular uptake of high density lipoprotein (HDL) and regulation of sterol regulatory element-binding protein-1 (SREBP-1) was investigated in vitro. HDL decreased nuclear SREBP-1 levels as well as SREBP-1 target gene expression in HepG2 and HEK293 cells. However, HDL did not repress an exogenously expressed, constitutively active form of SREBP-1. HDL increased cellular cholesterol levels, and cellular cholesterol depletion by methyl-beta-cyclodextrin abolished the effects of HDL. These results suggest that HDL inhibits the activation of SREBP-1 through a cholesterol-dependent mechanism, which may play an important role in regulating lipid synthetic pathways mediated by SREBP-1.
Hattori Atsushi, Kazuaki Mawatari, Tuzuki Satomi, Yoshioka Emiko, Toda Satomi, Yoshida Masaki, Yasui Sonoko, Furukawa Hiroko, Morishima Masaki, Ono Katsushige, Takamasa Ohnishi, Nakano Masayuki, Nagakatsu Harada, Akira Takahashi and Yutaka Nakaya : β-Adrenergic-AMPK Pathway Phosphorylates Acetyl-CoA Carboxylase in a High-epinephrine Rat Model, SPORTS, Obesity, Vol.18, No.1, 48-54, 2010.
(要約)
We established a new animal model called SPORTS (Spontaneously-Running Tokushima-Shikoku) rats, which show high-epinephrine (Epi) levels. Recent reports show that Epi activates adenosine monophosphate (AMP)-activated protein kinase (AMPK) in adipocytes. Acetyl-CoA carboxylase (ACC) is the rate-limiting enzyme in fatty acid synthesis, and the enzymatic activity is suppressed when its Ser-79 is phosphorylated by AMPK. The aim of this study was to investigate the in vivo effect of Epi on ACC and abdominal visceral fat accumulation. We divided both 6-week male control and SPORTS rats into two groups, which were fed either normal diet or high fat and sucrose (HFS) diet for 16 weeks. At the end of diet treatment, retroperitoneal fat was collected for western blotting and histological analysis. Food intake was not different among the groups, but SPORTS rats showed significantly lower weight gain than control rats in both diet groups. After 10 weeks of diet treatment, glucose tolerance tests (GTTs) revealed that SPORTS rats had increased insulin sensitivity. Furthermore, SPORTS rats had lower quantities of both abdominal fat and plasma triglyceride (TG). In abdominal fat, elevated ACC Ser-79 phosphorylation was observed in SPORTS rats and suppressed by an antagonist of beta-adrenergic receptor (AR), propranolol, or an inhibitor of AMPK, Compound C. From these results, high level of Epi induced ACC phosphorylation mediated through beta-AR and AMPK signaling pathways in abdominal visceral fat of SPORTS rats, which may contribute to reduce abdominal visceral fat accumulation and increase insulin sensitivity. Our results suggest that beta-AR-regulated ACC activity would be a target for treating lifestyle-related diseases, such as obesity.
Gadelmoula Mostafa, Lian Xin, Maeda Miku, Aihara Mutsumi, Kazuaki Mawatari, Hamamoto Akiko, Harada Yumi, Masayuki Yamato, Masatake Akutagawa, Yutaka Nakaya, Yohsuke Kinouchi and Akira Takahashi : Suitability of ultraviolet(A)-light emitting diode for air stream disinfection, The Journal of Medical Investigation : JMI, Vol.56, No.3-4, 150-156, 2009.
(要約)
We previously developed a high powered light-emitting diode device capable of discharging germicidal ultraviolet irradiation (UVA-LED) at an approximate wavelength of 365 nm. This study examined the bactericidal activity of UVA-LED in moving air streams. Aerosols of Escherichia coli DH5alpha were exposed to UVA-LED irradiation using a stable current (0.5 A and 1.2 mW/cm(2)) or pulse current (1.0 A and 0.2 mW/cm(2)). Settle plate analysis was used for bioaerosol sampling, where results were expressed as Colony Forming Units. A -3 Log inactivation of the E. coli population occurred after 75 minutes of constant exposure to stable current. The pulse current produced inactivation within a similar timeframe. Our results might be significant as a basic study for further investigations about the effect of UVA-LED on airborne bacteria and its suitability for air disinfection applications.
(キーワード)
Aerosols / Air Microbiology / Air Pollution, Indoor / Disinfection / 大腸菌 (Escherichia coli) / Humans / Sick Building Syndrome / Ultraviolet Rays
hua Yin, Nagakatsu Harada, Kazuaki Mawatari, Yasui Sonoko, Hiroko Segawa, Akira Takahashi, Shuzo Oshita and Yutaka Nakaya : L-DOPA inhibits nitric oxide-dependent vasorelaxation via production of reactive ozygen species in rat aorta, The Journal of Medical Investigation : JMI, Vol.56, No.3,4, 120-129, 2009.
(要約)
To clarify the underlying mechanisms of L-DOPA induced vasoconstriction in rat aorta. Methods: The effect of L-DOPA on phenylephrine-induced contractile force of blood vessels was examined in vitro using rat aortic ring preparations by isometric tension experiment. Involvement of nitric oxide (NO) in the effect of L-DOPA on vascular smooth muscle was studied by using N(omega)-Nitro-L-arginine (L-NNA), Sodium nitroprusside (SNP) in endothelium-intact and endothelium-denuded aortic rings. L-DOPA potentiated alpha-adrenergic receptor- and depolarization-induced vascular contraction and inhibited acetylcholine-induced vasorelaxation. This effect was diminished by pretreatment of the aortic rings with L-NNA, an inhibitor of NO synthesis, or by removing the endothelium from the ring preparations. In endothelium-denuded rings, L-DOPA inhibited exogenous NO-dependent but not cGMP-mediated vasorelaxation. Increases in cGMP levels in response to an NO donor were attenuated by L-DOPA in cultured rat aortic smooth muscle cells. L-DOPA could not contract rings (without endothelium) pretreated with 3-(5'-hydroxymethyl- 2'-furyl)-1-benzyl indazole (YC-1), an activator of guanylyl cyclase, but SOD (150 U/ml) pretreatment of rings with endothelium inhibited contraction by L-DOPA. These results suggest that L-DOPA inhibits nitric-dependent vasorelaxation on vascular smooth muscle cells via production of reactive oxygen species.
Masaki Yoshida, Nagakatsu Harada, Hironori Yamamoto, Yutaka Taketani, Nagakatsu Harada, Yunjie Yin, Atsushi Hattori, Tomoe Zenitani, Sayuri Hara, Haruka Yonemoto, Aki Nakamura, Masayuki Nakano, Kazuaki Mawatari, Kiyoshi Teshigawara, Hidekazu Arai, Toshio Hosaka, Akira Takahashi, Katsuhiko Yoshimoto and Yutaka Nakaya : Identification of cis-acting promoter sequences required for expression of the glycerol-3-phosphate acyltransferase 1 gene in mice., Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, Vol.1791, No.1, 39-52, 2009.
(要約)
Glycerol-3-phosphate acyltransferase 1 (GPAT1) is a rate limiting enzyme in de novo glycerophospholipid synthesis. The murine GPAT1 promoter sequence (the "classical" sequence) was reported previously. However, the organization of this DNA sequence does not fully match the mouse genome sequences on NCBI/GenBank. Here we have identified net cis-acting promoter sequences for the mouse GPAT1 gene: promoter 1a which includes part of the classical sequence and the downstream promoter 1b. Promoter 1a facilitates transcription of two alternative GPAT1 transcript variants, GPAT1-V1 and V2, while promoter 1b produces a third transcript variant, GPAT1-V3. Upstream stimulating factor-1 (USF-1) controlled both promoters whereas sterol regulatory element-binding protein-1 (SREBP-1) exclusively regulated promoter 1a activity in vitro. Feeding increased GPAT1-V1 and V2, but not V3 mRNA levels in mouse liver. The obese condition of db/db mice did not alter the hepatic expression levels of any of the three GPAT1 variants. Feeding enhanced hepatic mRNA levels, intranuclear protein levels and promoter 1a-binding levels of SREBP-1, but not of USF-1. Thus, promoter 1a was exclusively activated by routine feeding in vivo. Our results indicate differential roles of the two promoters in the regulation of hepatic GPAT1 gene expression in mice.
M Nakano, Akira Takahashi, Z Su, Nagakatsu Harada, Kazuaki Mawatari and Yutaka Nakaya : Hfq regulates the expression of the thermostable direct hemolysin gene in Vibrio parahaemolyticus, BMC Microbiology, Vol.8, 155, 2008.
(要約)
The hfq gene is conserved in a wide variety of bacteria and Hfq is involved in many cellular functions such as stress responses and the regulation of gene expression. It has also been reported that Hfq is involved in bacterial pathogenicity. However, it is not clear whether Hfq regulates virulence in Vibrio parahaemolyticus. To evaluate this, we investigated the effect of Hfq on the expression of virulence-associated genes including thermostable direct hemolysin (TDH), which is considered to be an important virulence factor in V. parahaemolyticus, using an hfq deletion mutant. The production of TDH in the hfq deletion mutant was much higher than in the parental strain. Quantification of tdh promoter activity and mRNA demonstrated that transcription of the tdh gene was up-regulated in the mutant strain. The hfq-complemented strain had a normal (parental) amount of tdh expression. The transcriptional activity of tdhA was particularly increased in the mutant strain. These results indicate that Hfq is closely associated with the expression level of the tdh gene. Interestingly, other genes involved in the pathogenicity of V. parahaemolyticus, such as VP1680, vopC, and vopT, were also up-regulated in the mutant strain. Hfq regulates the expression of virulence-associated factors such as TDH and may be involved in the pathogenicity of V. parahaemolyticus.
Isoflurane activates vascular adenosine triphosphate sensitive potassium (K(ATP)) channels, and may induce vasodilation. In the present study, we investigated whether hyperglycemia modifies isoflurane activation of vascular K(ATP) channel. We used a cell-attached patch-clamp configuration to test the effects of isoflurane on K(ATP) channel activity in vascular smooth muscle cells (VSMCs) after incubation for 24 h in medium containing normal glucose (NG, 5.5 mM D-glucose), L-glucose (LG, 5.5 mM D-glucose plus 17.5 mM L-glucose), or high glucose (HG, 23 mM D-glucose). Superoxide levels in aortas were measured by the lucigenin-enhanced chemiluminescence technique. Isoflurane-induced open probabilities were significantly reduced in VSMCs from arteries incubated in HG (0.06 +/- 0.01) compared with NG (0.17 +/- 0.02; P < 0.05) and LG (0.15 +/- 0.02; P < 0.05). Pretreatment of VSMCs with protein kinase C (PKC) inhibitors, calphostin C and PKC inhibitor 20-28, greatly reduced HG inhibition of isoflurane-induced K(ATP) channel activity. In addition, a PKC activator, PMA, mimicked the effects of HG. Superoxide release was significantly increased in arteries incubated in HG (18.3 +/- 11.5 relative light units (RLU) x s(-1) x mg(-1); P < 0.05 versus NG). Coincubated with polyethylene glycol-superoxide dismutase (250 U/mL), a cell-permeable superoxide scavenger, greatly reduced the HG-induced increase of superoxide, but failed to reduce HG inhibition of isoflurane-induced K(ATP) channel activity. Our results suggest that the metabolic stress of hyperglycemia can impair isoflurane-induced vascular K(ATP) channel activity mediated by excessive activation of PKC. This could impede the coronary vasodilation response to isoflurane, causing ischemia or hypoxia in patients with perioperative hyperglycemia.
Nagakatsu Harada, Haruka Yonemoto, Masaki Yoshida, Hironori Yamamoto, Yunjie Yin, Aiko Miyamoto, Atsushi Hattori, Qishisan Wu, Tadahiko Nakagawa, Masayuki Nakano, Kiyoshi Teshigawara, Kazuaki Mawatari, Toshio Hosaka, Akira Takahashi and Yutaka Nakaya : Alternative splicing produces a constitutively active form of human SREBP-1., Biochemical and Biophysical Research Communications, Vol.368, No.3, 820-826, 2008.
(要約)
We identified a novel alternative splicing event that constitutively produces a truncated active form of human sterol regulatory element-binding protein 1 (SREBP-1). A cDNA of this splicing variant (named SREBP-1Delta) contains a translational stop codon-encoding exon sequence between exons 7 and 8. It produces SREBP-1aDelta (470 a.a.) and SREBP-1cDelta (446 a.a.) proteins that lack transmembrane and C-terminal regulatory sequences necessary for localization of SREBP-1 to the endoplasmic reticulum. A luciferase reporter assay showed that SREBP-1aDelta and SREBP-1cDelta transactivated lipogenic gene promoters to the same extent as that induced by N-terminal active fragments of SREBP-1a and SREBP-1c, respectively. SREBP-1Delta mRNA is expressed in human cell lines as well as adipose and liver tissues. Expression levels ranged from 5% to 16% of total SREBP-1 expression. The ratio of SREBP-1Delta expression to total SREBP-1 expression in HepG2 cells was not affected by either insulin or high glucose treatment.
(キーワード)
Adipose Tissue / Alternative Splicing / Cell Line / Humans / Liver / Organ Specificity / Protein Isoforms / RNA Splice Sites / Sterol Regulatory Element Binding Protein 1 / Tissue Distribution
Takashi Kawano, Tomohito Kawano, Katsuya Tanaka, Satoru Eguchi, Akira Takahashi, Yutaka Nakaya and Shuzo Oshita : Effects of dopamine on ATP-sensitive potassium channels in porcine coronary artery smooth-muscle cells, Journal of Cardiovascular Pharmacology, Vol.51, No.2, 196-201, 2008.
(要約)
Dopamine is reported to be a coronary vasodilator; however, the exact mechanism of dopamine action in the coronary circulation remains unclear. In this study, we hypothesized that dopamine-induced activation of coronary ATP-sensitive potassium (KATP) channels may be associated with coronary vasodilation. We therefore investigated the direct effects of dopamine on coronary KATP-channel activity. We used patch-clamp configurations to investigate the effects of dopamine on coronary KATP-channel activity. Application of dopamine (10 to 10 M) to the bath solution during cell-attached recordings induced a concentration-dependent increase in KATP-channel activity. In contrast, dopamine failed to activate KATP channels in inside-out patches. Dopamine-induced coronary KATP-channel currents in cell-attached patches were inhibited by pretreatment with the selective D1-like antagonist, Sch-23390, but they were not influenced by the selective D2-like antagonist, domperidone, or the beta-adrenergic receptor antagonist, propranolol. The selective D1-like agonist, SKF-38393, and the adenylyl cyclase activator, forskolin, mimicked the dopamine effects on coronary KATP channels. Furthermore, pretreatment with an inhibitor of protein kinase A, Rp-cAMPS, abolished the dopamine-induced KATP-channel activation. This study demonstrates that dopamine activates coronary KATP channels via signal transduction involving the D1-like dopaminergic receptor-protein kinase A-signaling pathway.
Qishisan Wu, Nagakatsu Harada, Aki Nakamura, Masaki Yoshida, Kazuaki Mawatari, Atsushi Hattori, Qinkai Li, Takaaki Shimohata, (名) Yinhua, Xin Lian, Masayuki Nakano, Toshio Hosaka, Akira Takahashi and Yutaka Nakaya : NO-1886, a lipoprotein lipase activator, attenuates contraction of rat intestinal ring preparations, The Journal of Medical Investigation : JMI, Vol.55, No.1,2, 61-70, 2008.
(要約)
Various intestinal symptoms or diseases are closely associated with intestinal motility, which may be altered by metabolic disturbances associated with diabetes and obesity. It is therefore important that drugs used in the treatment of metabolic disorders should not have any adverse effects on the intestine. In the present study, we examined whether [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886), a lipoprotein lipase activator with anti-diabetic and/or anti-obese activity, affects stimulant-induced intestinal contractility. Administration of NO-1886 to intestinal ring preparations of ileum, rectum and colon isolated from Wistar rats attenuated or relaxed contraction induced by a high K+ environment or acetylcholine (ACh). This effect of NO-1886 was dependent on extracellular Ca(2+) and intracellular myosin light chain kinase activity. Our results also showed that ACh-induced colonic contraction was significantly higher in the obese Otsuka Long-Evans Tokushima Fatty (OLETF) than in the non-obese Long-Evans Tokushima Otsuka (LETO) rats. The hypercontractility observed in the colons of OLETF rats occurred concomitantly with an elevation in muscarinic M3 ACh receptor protein levels. Administration of NO-1886 attenuated the obesity-induced hypercontractility of the colonic rings of OLETF rats. Thus, intestinal contractile system would be a novel pharmacological target of the lipoprotein lipase activator NO-1886.
Satoru Eguchi, Takashi Kawano, hua Yin, Katsuya Tanaka, Sonoko Yasui, Kazuaki Mawatari, Akira Takahashi, Yutaka Nakaya, Shuzo Oshita and Nobuyoshi Nakajo : Effects of prostaglandin E1 on vascular ATP-sensitive potassium channels., Journal of Cardiovascular Pharmacology, Vol.50, No.6, 686-691, 2007.
(要約)
BACKGROUND: Prostaglandin E1 (PGE1) has been reported to activate ATP-sensitive potassium (KATP) channels, which induces vasorelaxation. However, direct evidence of PGE1 interactions with vascular KATP channels is limited. METHODS: The present study investigated the effects and mechanisms of PGE1 on vascular KATP channels in both isometric tension and patch clamp experiments.Isometric tension experiments were performed in rat thoracic aortic rings without an endothelium. Electrophysiologic experiments were performed using patch-clamp techniques to monitor KATP channels in rat vascular smooth muscle cells. RESULTS: PGE1 significantly decreased the isometric tension in a concentration-dependent manner, which was partially inhibited by pretreating with a KATP channel inhibitor, glibenclamide (1 microM), or an inhibitor of protein kinase A (PKA), Rp-cAMPS (100 microM). Application of PGE1 to the bath solution during cell-attached recordings induced a significant increase in KATP channel activity, whereas PGE1 failed to activate KATP channels in the inside-out patches. The PGE1-induced KATP channel currents in cell-attached patches were abolished by pretreating with Rp-cAMPS (100 microM). CONCLUSIONS: The results indicate that the activation of vascular KATP channels played an important role in the PKA-dependent PGE1-induced vasorelaxation. Furthermore, an electrophysiological experiment demonstrated that PGE1 activated vascular KATP channels via PKA activation.
Mirei Mori, Hamamoto Akiko, Akira Takahashi, Nakano Masayuki, Wakikawa Noriko, Tachibana Satoko, Toshitaka Ikehara, Yutaka Nakaya, Masatake Akutagawa and Yohsuke Kinouchi : Development of a new water sterilization device with a 365 nm UV-LED, Medical and Biological Engineering and Computing, Vol.45, No.12, 1237-1241, 2007.
Akiko Hamamoto, Mirei Mori, Akira Takahashi, Masayuki Nakano, Noriko Wakikawa, Masatake Akutagawa, Toshitaka Ikehara, Yutaka Nakaya and Yohsuke Kinouchi : New water disinfection system using UVA-light emitting diodes., Journal of Applied Microbiology, Vol.103, No.6, 2291-2298, 2007.
(要約)
To evaluate the ability of high-energy ultraviolet A (UVA) light-emitting diode (LED) to inactivate bacteria in water and investigate the inactivating mechanism of UVA irradiation. We developed a new disinfection device equipped with high-energy UVA-LED. Inactivation of bacteria was determined by colony-forming assay. Vibrio parahaemolyticus, enteropathogenic Escherichia coli, Staphylococcus aureus and Escherichia coli DH5alpha were reduced by greater than 5-log(10) stages within 75 min at 315 J cm(-2) of UVA. Salmonella enteritidis was reduced greater than 4-log(10) stages within 160 min at 672 J cm(-2) of UVA. The formation of 8-hydroxy-2'-deoxyguanosine in UVA-LED irradiated bacteria was 2.6-fold higher than that of UVC-irradiated bacteria at the same inactivation level. Addition of mannitol, a scavenger of hydroxyl radicals (OH(*)), or catalase, an enzyme scavenging hydrogen peroxide (H(2)O(2)) to bacterial suspensions significantly suppressed disinfection effect of UVA-LED. This disinfection system has enough ability to inactivate bacteria and OH(*) and H(2)O(2) participates in the disinfection mechanism of UVA irradiation. We newly developed UVA irradiation system and found that UVA alone was able to disinfect the water efficiently. This will become a useful disinfection system.
Hirohide Yamada, Takashi Kawano, Katsuya Tanaka, Sonoko Yasui, Kazuaki Mawatari, Akira Takahashi, Yutaka Nakaya and Shuzo Oshita : Effects of intracellular MgADP and acidification on the inhibition of cardiac sarcolemmal ATP-sensitive potassium channels by propofol, Journal of Anesthesia, Vol.21, No.4, 472-479, 2007.
(要約)
Propofol inhibits adenosine triphosphate-sensitive potassium (K(ATP)) channels, which may result in the blocking of ischemic preconditioning in the heart. During cardiac ischemia, sarcolemmal K(ATP) channel activity is regulated by the increased levels of cytosolic metabolites, such as adenosine diphosphate (ADP) and protons. However, it remains unclear whether these cytosolic metabolites modulate the inhibitory action of propofol. The aim of this study was to investigate the effects of intracellular MgADP and acidification on K(ATP) channel inhibition by propofol. We used inside-out patch-clamp configurations to investigate the effects of propofol on the activities of recombinant cardiac sarcolemmal K(ATP) channels, which are reassociated by expressed subunits, sulfonylurea receptor (SUR) 2A, and inwardly rectifying potassium channels (Kir6.2). In the absence of MgADP, propofol inhibited the SUR2A/Kir6.2 channel currents in a concentration-dependent manner, and an IC(50) of 78 microM. Increasing the intracellular MgADP concentrations to 0.1 and 0.3 mM markedly attenuated the inhibitory potency of propofol, and shifted the IC(50) to 183 and 265 microM, respectively. Moreover, decreasing the intracellular pH from 7.4 to 6.5 attenuated the inhibitory potency of propofol, and shifted the IC(50) to 277 microM. In addition, propofol-induced inhibition of truncated Kir6.2DeltaC36 currents, which form a functional channel without SUR2A, was not affected by an increase in intracellular MgADP. However, intracellular acidification (pH 6.5) significantly reduced the propofol sensitivity of Kir6.2DeltaC36 channels. Our results demonstrated that the existence of intracellular MgADP and protons attenuated the direct inhibitory potency of propofol on recombinant cardiac sarcolemmal K(ATP) channels, via SUR2A and Kir6.2 subunits, respectively.
Lian Xin, Akira Takahashi, Nakano Masayuki, Hori Emiko, Kazuaki Mawatari, Nagakatsu Harada, Toshio Hosaka and Yutaka Nakaya : Vibrio parahaemolytics elevates interferon aloha production in intestinal-like epithelial Caco-2 cells, Canadian Journal of Microbiology, Vol.53, No.9, 1084-1090, 2007.
(要約)
Vibrio parahaemolyticus is the leading cause of gastroenteritis from seafood consumption. We tried to determine how the gene expression levels of intestinal-like epithelial cells (Caco-2 cells) and mouse intestinal loop mucosal cells change upon infection with this bacterium. Since we found the robust production of interferon alpha (IFN-alpha) by the V. parahaemolyticus infection, we also assessed the upregulation of a number of IFN-stimulated genes (ISGs). The expressions of IFN protein were determined by Western blotting, and the gene expressions of Caco-2 cells after V. parahaemolyticus infection were determined by quantitative real-time reverse-transcription polymerase chain reaction. Three ISGs (i.e., IFN-alpha-inducible protein 15, IFN-alpha-inducible protein 6-16, and IFN-induced protein with tetratricopeptide repeats 1) were upregulated by V. parahaemolyticus infection. Infection induced the production of IFN-alpha, but not IFN-beta or IFN-gamma. The upregulation of the 3 ISGs was suppressed by treatment with a neutralizing IFN-alpha antibody. Moreover, the production of infection-induced IFN-alpha was found in the mouse intestinal loop mucosal cells. V. parahaemolyticus infection of Caco-2 cells results in IFN-alpha production and the expression of IFN-regulated genes.
Masori Maria, Hamamoto Akiko, Kazuaki Mawatari, Nagakatsu Harada, Akira Takahashi and Yutaka Nakaya : Angiotensin Decreases Glucose Uptake by Downregulation of GLUT1 in the Cell Membrene of the Vascular Smooth Muscule Cell Line A10, Journal of Cardiovascular Pharmacology, Vol.50, No.3, 267-273, 2007.
(要約)
Recent evidence suggests a crosstalk between angiotensin II (Ang II) and insulin. However, whether this crosstalk affects glucose uptake, particularly in terms of actin filament involvement, has not yet been studied in vascular smooth muscle cells. Pretreatment of cells with either Ang II or cytochalasin D disarranged actin filaments in a time-dependent manner and inhibited glucose uptake. However, insulin increased actin reorganization and glucose uptake. Membrane fractionation studies showed that Ang II decreased GLUT-1 at the cell membrane, whereas it increased GLUT-1 in the cytoplasm, indicating that Ang II may cause internalization of GLUT-1 via actin disorganization, consequently decreasing glucose uptake. The effects of Ang II on glucose uptake and actin reorganization were blocked by AT1 receptor antagonist, but not by AT2 antagonist. Either P38 or ERK1/2 inhibitors partially reversed the Ang II-inhibited actin reorganization and glucose uptake, suggesting that MAPK signaling pathways could be involved as downstream events in Ang II signaling, and this signaling may interfere with insulin-induced actin reorganization and glucose uptake. These data imply that Ang II induces insulin resistance by decreasing glucose uptake via disarrangement of actin filaments, which provides a novel insight into understanding of insulin resistance by Ang II at the molecular level.
(キーワード)
Actins / Angiotensin II / Animals / Cell Fractionation / Cell Line / Cell Membrane / Cytochalasin D / Down-Regulation / Glucose / Glucose Transporter Type 1 / Insulin / Insulin Resistance / MAP Kinase Signaling System / Muscle, Smooth, Vascular / Rats / Time Factors
Ono Kaori, Kazuaki Mawatari, Nagakatsu Harada, Akira Takahashi, Tohru Sakai, Ogoshi Shohei and Yutaka Nakaya : Nucleoside and nucleotide mixture OG-VI rescues cytotoxicity induced by chemotherapeutic agents in intestinal-like epithelial cell., The Journal of Medical Investigation : JMI, Vol.54, No.3,4, 235-242, 2007.
(要約)
Immune cells and cells undergoing rapid turn-over can obtain exogenous nucleotides via salvage synthesis. We evaluated whether or not the balanced nucleoside and nucleotide mixture OG-VI, could rescue intestinal epithelial-like Caco-2 cells from the cytotoxic effects of several chemotherapeutic agents, in the presence and absence of glutamine (Gln). Cells were exposed to 5-fluorouracil (5FU), methotrexate (MTX) or 6-mercaptopurine (6MP), after which proliferation and cell cycle analyses were performed. Following exposure to the chemotherapeutic agents, we observed that cells treated with OG-VI proliferated well, whereas those without the supplement did not proliferate. Furthermore, following treatment with either 5FU or MTX, we observed that the number of cells in the G0/G1 phase decreased and those in the S phases increased. However, these cell cycle alterations were prevented by the addition of OG-VI. With the exception of 6MP-treated cells, we did not observe any effects on proliferation or cell cycle regulation that could be ascribed to the presence of Gln. Thus, we have demonstrated that OG-VI rescues cells from the cytotoxic effects of several chemotherapeutic agents.
Masayuki Nakano, Akira Takahashi, Y Sakai, M Kawano, Nagakatsu Harada, Kazuaki Mawatari and Yutaka Nakaya : Catecholamine-induced stimulation of growth in Vibrio species., Letters in Applied Microbiology, Vol.44, No.6, 649-653, 2007.
(要約)
To evaluate the effect of norepinephrine (NE) and related compounds on the growth of bacteria, we have examined the effect of the neuroendocrine hormone NE and related compounds on the growth of Vibrio parahaemolyticus and other human-pathogenic Vibrio species (Vibrio cholerae, Vibrio vulnificus, and Vibrio mimicus). The effects on bacterial growth were examined using the serum-based medium and viable cells were counted using agar plates. We have shown that NE and its related compounds stimulate growth of V. parahaemolyticus in serum-based medium. This NE-induced growth stimulation was dependent upon the presence of transferrin. NE also stimulated growth of V. mimicus, but not V. cholerae and V. vulnificus. These results suggest that the Vibrio species differ in their ability to respond to NE. It is possible that NE and related compounds modulate the pathogenicity of V. parahaemolyticus and V. mimicus.
Nakamura Akiyo, Shinji Kawahito, Takashi Kawano, Nazari Hossein, Akira Takahashi, Hiroshi Kitahata, Yutaka Nakaya and Shuzo Oshita : Differential Effects of Etomidate and Midazolam on Vascular Adenosine Triphosphate-sensitive Potassium Channels: Isometric Tension and Patch Clamp Studies., Anesthesiology, Vol.106, No.3, 515-522, 2007.
(要約)
The aim of this study was to investigate the effects of two imidazoline-derived intravenous anesthetics, etomidate and midazolam, on vascular adenosine triphosphate-sensitive potassium (KATP) channel activity. In isolated rat aorta, isometric tension was recorded to examine the anesthetic effects on vasodilator response to levcromakalim, a selective KATP channel opener. Using the patch clamp method, the anesthetic effects were also examined on the currents through (1) native vascular KATP channels, (2) recombinant KATP channels with different combinations of various types of inwardly rectifying potassium channel (Kir6.0 family: Kir6.1, 6.2) and sulfonylurea receptor (SUR1, 2A, 2B) subunits, (3) SUR-deficient channels derived from a truncated isoform of Kir6.2 subunit (Kir6.2DeltaC36 channels), and (4) mutant Kir6.2DeltaC36 channels with reduced sensitivity to adenosine triphosphate (Kir6.2DeltaC36-K185Q channels). Etomidate (> or = 10 m), but not midazolam (up to 10 m), inhibited the levcromakalim-induced vasodilation, which was sensitive to glibenclamide (IC50: 7.21 x 10 m; maximum inhibitory concentration: 1.22 x 10 m). Etomidate (> or = 3 x 10 m), but not midazolam (up to 10 m), inhibited the native KATP channel activity in both cell-attached and inside-out configurations with IC50 values of 1.68 x 10 m and 1.52 x 10 m, respectively. Etomidate (10 m) also inhibited the activity of various types of recombinant SUR/Kir6.0KATP channels, Kir6.2DeltaC36 channels, and Kir6.2DeltaC36-K185Q channels with equivalent potency. Clinical concentrations of etomidate, but not midazolam, inhibit the KATP channel activity in vascular smooth muscle cells. The inhibition is presumably through its effects on the Kir6.0 subunit, but not on the SUR subunit, with the binding site different from adenosine triphosphate at the amino acid level.
Katsuya Tanaka, Takashi Kawano, Akiyo Nakamura, Hossein Nazari, Shinji Kawahito, Shuzo Oshita, Akira Takahashi and Yutaka Nakaya : Isoflurane activates sarcolemmal adenosine Triphosphate-sensitive potassium channels in vascular smooth muscle cells: A role of protein kinase A, Anesthesiology, Vol.106, No.5, 984-991, 2007.
(要約)
Recent evidence indicates that vascular adenosine triphosphate-sensitive potassium (K(ATP)) channels in vascular smooth muscle cells are critical in the regulation of vascular tonus under both physiologic and pathophysiologic conditions. Studies of the interaction of volatile anesthetics with vascular K(ATP) channels have been limited. In the current study, the authors investigated the molecular mechanism of isoflurane's action on vascular K(ATP) channels. Electrophysiologic experiments were performed using cell-attached and inside-out patch clamp techniques to monitor native vascular K(ATP) channels, and recombinant K(ATP) channels comprised of inwardly rectifying potassium channel subunits (Kir6.1) and the sulfonylurea receptor (SUR2B). Isometric tension experiments were performed in rat thoracic aortic rings without endothelium. Application of isoflurane (0.5 mM) to the bath solution during cell-attached recordings induced a significant increase in K(ATP) channel activity, which was greatly reduced by pretreatment with a selective inhibitor of protein kinase A (PKA), Rp-cAMPS (100 microM). In inside-out patches, isoflurane did not activate K(ATP) channels. Isoflurane significantly activated wild-type recombinant SUR2B/Kir6.1 in cell-attached patches. Isoflurane-induced activation of wild-type channels was diminished in the PKA-insensitive mutant SUR2B-T633A/Kir6.1, SUR2B-S1465A/Kir6.1, and SUR2B/Kir6.1-S385A. In addition, the authors demonstrated that isoflurane-induced PKA activation was associated with isoflurane-induced decreases in isometric tension in the rat aorta. These results indicate that isoflurane activates K(ATP) channels via PKA activation. PKA-dependent vasodilation induced by isoflurane also was observed in isometric tension experiments. Analysis of expressed vascular-type K(ATP) channels suggested that PKA-mediated phosphorylation of both Kir6.1 and SUR2B subunits plays a pivotal role in isoflurane-induced vascular K(ATP) channel activation.
Nagakatsu Harada, A Kusuyama, M Morishima, Kazuko Okada, Akira Takahashi and Yutaka Nakaya : Bezafibrate improves bacterial lipopolysaccharide-induced dyslipidemia and anorexia in rats., Metabolism: Clinical and Experimental, Vol.56, No.4, 517-522, 2007.
(要約)
Bacterial endotoxin/lipopolysaccharide (LPS)-induced cachexia is characterized by weight loss, anorexia, and a disturbance in lipid metabolism, namely, hypertriacylglycerolemia. The aim of this study in rats with acute endotoxicity induced by an injection of LPS was to investigate whether bezafibrate, a ligand for peroxisome proliferator-activated receptor alpha and a lipoprotein lipase (LPL) activator, improved cachectic conditions, including impaired lipid metabolism. Short-term administration of LPS in the rats resulted in impairment of triacylglycerol clearance in plasma after the intake of fresh cream. In addition, LPS increased whole-body energy expenditure, reduced fasting body weight and caused anorexia in the rats. Bezafibrate treatment resulted in significant improvements in LPS-induced dyslipidemia and anorexia, but had no effect on energy expenditure, respiratory quotient, or fasting body weight in the endotoxic rats. Administration of LPS was also associated with a decrease in the level of messenger RNA (mRNA) expression for LPL in white adipose tissue and skeletal muscle and an increase in the mRNA levels for uncoupling protein 3 in skeletal muscle. Bezafibrate treatment reversed the decline in LPL mRNA levels in white adipose tissue but not in the skeletal muscle tissue of the rats. The enhanced uncoupling protein 3 mRNA level in the endotoxic rats was not affected by bezafibrate treatment. Plasma concentration of leptin was increased by short-term LPS treatment. Bezafibrate decreased the level of plasma leptin significantly without affecting the level of leptin mRNA expression. These results suggest that bezafibrate may be an effective drug not only for impaired triacylglycerol metabolism, but also for anorexia in cachectic states induced by bacterial infections.
Y Wang, Morishima Masaki, M Zheng, T Uchino, K Mannen, Akira Takahashi, Yutaka Nakaya, I Komuro and K Ono : Transcription factors Csx/Nkx2.5 and GATA4 distinctly regulate expression of Ca2+ channels in neonatal rat heart., Journal of Molecular and Cellular Cardiology, Vol.42, No.6, 1045-1053, 2007.
(要約)
The cardiac transcription factors Csx/Nkx2.5 and GATA4 play important roles in vertebrate heart development. Although mutations of Csx/Nkx2.5 or GATA4 are associated with various congenital heart diseases, their mechanism of action on cardiomyocyte function is not completely elucidated. In this study, we therefore investigated the actions of these transcription factors on the electrophysiological features and expression of ion channels in cardiomyocytes. Genes for transcription factors Csx/Nkx2.5 and GATA4 were transfected into rat neonatal cardiomyocytes by adenoviral infection. Action potentials, L-, T-type Ca(2+) channels and hyperpolarization-activated cation current (I(h)) of rat neonatal myocytes were recorded by patch clamp technique after adenoviral infection. Expression of ion channels was confirmed by real-time PCR. In Csx/Nkx2.5 overexpression myocytes, the spontaneous beating rate was markedly increased with an up-regulation of the Ca(v)3.2 T-type Ca(2+) channel, while in GATA4 overexpression myocytes, the T-type Ca(2+) channel was unchanged. On the other hand, the L-type Ca(2+) channel was down-regulated by both Csx/Nkx2.5 and GATA4 overexpression; the level of Ca(v)1.3 mRNA was dramatically decreased by Csx/Nkx2.5 overexpression. These results indicate that Csx/Nkx2.5 and GATA4 play important roles on the generation of pacemaker potentials modulating voltage-dependent Ca(2+) channels in the neonatal cardiomyocyte.
M Nakano, Akira Takahashi, Y Sakai and Yutaka Nakaya : Modulation of Pathogenicity with Norepinephrine Related to the Type III Secretion System of Vibrio parahaemolyticus., The Journal of Infectious Diseases, Vol.195, No.9, 1353-1360, 2007.
(要約)
Norepinephrine (NE) controls the functions of the gastrointestinal tract, but its role in the pathogenicity of enteropathogens is not clear. We examined the effect of NE on the pathogenicity of Vibrio parahaemolyticus with regard to its type III secretion systems (TTSSs). To evaluate the effect of NE on pathogenicity of V. parahaemolyticus, we examined the cytotoxic activity to Caco-2 cells and enterotoxicity by use of the rat ileal loop model. It has been reported that TTSS1 causes cytotoxicity and that TTSS2 causes enterotoxicity in the animal ileal loop model. Our results showed that, although NE alone did not affect the viability of Caco-2 cells, NE stimulated the cytotoxic activity of V. parahaemolyticus. Furthermore, NE increased the transcription of the TTSS1-related genes vscQ and vscU. These results indicate that NE regulates V. parahaemolyticus cytotoxic activity. The enterotoxicity of V. parahaemolyticus was increased by NE through interaction with alpha (1)-adrenergic receptors. These results indicate that alpha (1)-adrenergic receptors on the intestinal epithelium appear to interact with V. parahaemolyticus enterotoxicity. The present findings suggest that enteric NE may modulate V. parahaemolyticus pathogenicity.
Hossein Nazari, Akira Takahashi, Nagakatsu Harada, Kazuaki Mawatari, Masayuki Nakano, Kazuhiro Kishi, Yousuke Ebina and Yutaka Nakaya : Angiotensin II inhibits insulin-induced actin stress fiber formation and glucose uptake via ERK1/2., The Journal of Medical Investigation : JMI, Vol.54, No.1,2, 19-27, 2007.
(要約)
There is crosstalk in intracellular signaling between Angiotensin II (Ang II) and insulin. We hypothesized that the underlying mechanism might be related to changes in cytoskeleton. In the presence of 100 nM of Ang II, insulin-induced glucose uptake was decreased and insulin-induced actin filament organization was inhibited. PKC inhibitors, including GF109203x and p38MAPK inhibitor (SB203580) neither improved insulin-induced actin reorganization nor glucose uptake. In contrast, the Ang II-induced inhibition of glucose uptake and actin filament disorganization was reversed by 10 micromol ERK 1/2 MAPK inhibitor (PD98059). Pretreatment of Ang II increased ERK1/2 phosphorylation and inhibited insulin-induced Akt phosphorylation. The effect of Ang II on ERK1/2 phosphorylation was blocked by Ang II type 1 receptor antagonists, RNH6270 and PD98059 but not by SB203580 or Guanosine-5'-O-(2-ThioDiphosphate), a G-protein inhibitor. We next tested the effect of broad-spectrum matrix metalloproteinase (MMP) inhibitor (GM6001) on Ang II-inhibition of insulin signaling pathway. GM6001 did not improve Ang II-induced actin filament disorganization and did not inhibit ERK1/2 phosphorylation. From these data in L6 myotube, we conclude that Ang II negatively regulates the insulin signal not through MMP signaling pathway but specifically through MMP-independent ERK1/2 activation pathway, providing an alternative molecular mechanism for angiotensin-induced insulin resistance.
(キーワード)
Angiotensin II / Cell Line / グルコース (glucose) / Humans / インスリン (insulin) / MAP Kinase Signaling System / Mitogen-Activated Protein Kinase 1 / Mitogen-Activated Protein Kinase 3 / リン酸化 (phosphorylation) / Proto-Oncogene Proteins c-akt / Receptor, Angiotensin, Type 1 / Stress Fibers
Nagakatsu Harada, S Hara, M Yoshida, T Zenitani, Kazuaki Mawatari, M Nakano, Akira Takahashi, Toshio Hosaka, Katsuhiko Yoshimoto and Yutaka Nakaya : Molecular cloning of a murine glycerol-3-phosphate acyltransferase-like protein 1 (xGPAT1)., Molecular and Cellular Biochemistry, Vol.297, No.1-2, 41-51, 2007.
(要約)
A novel murine glycerol-3-phosphate acyltransferase-like protein 1 (named xGPAT1) has been cloned. The mouse xGPAT1 gene is located on mouse Chromosome 2, spans >19 kb, and consists of at least 23 exons. The protein is 32% identical and 72% similar to mouse mitochondrial GPAT (mtGPAT) on the amino acid level. Sequencing analysis confirmed that xGPAT1 has a 2403-bp open reading frame (ORF) that encodes an 801-amino acid protein with an estimated molecular mass of 89.1 kDa. A hydropathy plot of the deduced xGPAT1 protein showed a high degree of similarity with that of the mtGPAT protein. Using 5'-rapid amplification of cDNA ends, two alternate, untranslated exon 1 (1a and b) isoforms were obtained, generating variants xGPAT1-v1 and xGPAT1-v2. xGPAT1-v1 is expressed in mouse heart, liver, spleen, kidney and murine inner medullary collecting duct 3 (mIMCD3) cells, while xGPAT1-v2 is expressed in mouse liver, spleen, kidney, white and brown adipose tissues and 3T3-L1 pre- and post-adipocytes. xGPAT1 was distributed in the membrane fraction and showed GPAT activity when epitope-tagged xGPAT1 was expressed in Chinese hamster ovary (CHO)-K1 cells.
A Nakamura, Nagakatsu Harada, Akira Takahashi, Kazuaki Mawatari, M Nakano, K Tsutsumi and Yutaka Nakaya : NO-1886, a lipoprotein lipase activator, attenuates vascular smooth muscle contraction in rat aorta, European Journal of Pharmacology, Vol.554, No.2-3, 183-190, 2007.
(要約)
The chemical compound [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886) is a lipoprotein lipase activator having beneficial effects on both diabetes control and the cardiovascular system. Preventing accumulation of lipids in the cell wall, in addition to improving insulin actions on vasculature, may indirectly contribute to the reducing effect of NO-1886 on vascular resistance. However, the direct effect of NO-1886 on vascular resistance, i.e., whether NO-1886 directly modulates the function of vascular endothelium and/or smooth muscle cells has not been investigated. In this study we therefore investigated the direct effect of NO-1886 on vascular contractility using rat aortic rings and cultured smooth muscle cell-line A10. The results show that administration of NO-1886 attenuated aortic contraction induced by phenylephrine and/or a high K(+) environment, in both the presence and absence of aortic endothelium. 1-(5-Chloronaphthalene-1-sulfonyl)homopiperazine hydrochloride (ML-9), a myosin light chain kinase (MLCK) inhibitor, blocked this inhibitory effect of NO-1886, whereas inhibitors of other signaling molecules such as calmodulin, protein kinase C and Rho-kinase had no effect. The vasorelaxant effect of NO-1886 was blocked in the absence of extracellular Ca(2+), or in the presence of the Ca(2+) channel inhibitor, verapamil. NO-1886 attenuated smooth muscle contraction induced by the cumulative addition of CaCl(2). In A10 cells, NO-1886 inhibited the membrane depolarization-induced initial peak of [Ca(2+)](i) in the presence of extracellular Ca(2+). This inhibition did not occur in the absence of extracellular Ca(2+). Taken together these results demonstrate that NO-1886 attenuates smooth muscle contraction and causes vasorelaxation by an extracellular Ca(2+)- and MLCK-dependent mechanism.
Akira Takahashi, SI Miyoshi, N Takata, M Nakano, A Hamamoto, Kazuaki Mawatari, Nagakatsu Harada, S Shinoda and Yutaka Nakaya : Haemolysin produced by Vibrio mimicus activates two Cl secretory pathways in cultured intestinal-like Caco-2 cells., Cellular Microbiology, Vol.9, No.3, 583-595, 2007.
(要約)
Haemolysin (VMH) is a virulent factor produced by Vibrio mimicus, a human pathogen that causes diarrhoea. As intestinal epithelial cells are the primary targets of haemolysin, we investigated its effects on ion transport in human colonic epithelial Caco-2 cells. VMH increased the cellular short circuit current (Isc), used to estimated ion fluxes, and 125I efflux of the cells. The VMH-induced increases in Isc and 125I efflux were suppressed by depleting Ca2+ from the medium or by pretreating the cells with BAPTA-AM or by Rp-adenosin 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS). The Cl- channel inhibitors 4,4'-disothiocyanatostibene-2,2'-disulfonic acid (DIDS), glybenclamide, and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) suppressed the VMH-induced increases in Isc and 125I efflux. Moreover, VMH increased the intracellular concentrations of Ca2+ and cAMP. Thus, VMH stimulates Caco-2 cells to secrete Cl- by activating both Ca2+ -dependent and cAMP-dependent Cl- secretion mechanisms. VMH forms ion-permeable pores in the lipid bilayer that are non-selectively permeable to small ions. However, the ion permeability of these pores was not inhibited by glybenclamide and DIDS, and VMH did not change the cell membrane potential. These observations indicate that the pores formed on the cell membrane by VMH are unlikely to be involved in VMH-induced Cl- secretion. Notably, VMH stimulated fluid accumulation in the iliac loop test that was fully suppressed by a combination of DIDS and glybenclamide. Thus, Ca2+-dependent and cAMP-dependent Cl- secretion may be important therapeutic targets with regard to the diarrhoea that is induced by Vibrio mimicus.
Akira Takahashi, Chiyo Yamamoto, Toshio Kodama, Kanami Yamashita, Nagakatsu Harada, Masayuki Nakano, Takeshi Honda and Yutaka Nakaya : Pore formation of thermostable direct hemolysin secreted from Vibrio parahaemolyticus in lipid bilayers., International Journal of Toxicology, Vol.25, No.5, 409-418, 2006.
(要約)
Vibrio parahaemolyticus secretes thermostable direct hemolysin (TDH), a major virulence factor. Earlier studies report that TDH is a pore-forming toxin. However, the characteristics of pores formed by TDH in the lipid bilayer, which is permeable to small ions, remain to be elucidated. Ion channel-like activities were observed in lipid bilayers containing TDH. Three types of conductance were identified. All the channels displayed relatively low ion selectivity, and similar ion permeability. The Cl- channel inhibitors, DIDS, glybenclamide, and NPPB, did not affect the channel activity of pores formed by TDH. R7, a mutant toxin of TDH, also forms pores with channel-like activity in lipid bilayers. The ion permeability of these channels is similar to that of TDH. R7 binds cultured cells and liposomes to a lower extent, compared to TDH. R7 does not display significant hemolytic activity and cell cytotoxicity, possibly owing to the difficulty of insertion into lipid membranes. Once R7 is assembled within lipid membranes, it may assume the same structure as TDH. The authors propose that the single glycine at position 62, substituted with serine in the R7 mutant toxin, plays an important role in TDH insertion into the lipid bilayer.
Aeromonas sobria hemolysin (ASH) is one of the major virulence factors produced by A. sobria, a causative agent of diarrhea in humans. We investigated the effects of ASH on anion transport in human colonic epithelial cells. ASH increased short circuit currents across the intestinal epithelia, which were suppressed by anion channel antagonists, such as carbonic anhydrase inhibitors, and by the removal of external HCO3-. Iliac fluid accumulation was also inhibited by carbonic anhydrase inhibitors. The results suggest that ASH activates HCO3- secretion, whose level correlates with the severity of diarrhea.
Rie Matsushima, Akira Takahashi, Yutaka Nakaya, Hiroshi Maezawa, Mari Miki, Youichi Nakamura, Fumitaka Ohgushi and Susumu Yasuoka : Human airway trypsin-like protease stimulates human bronchial fibroblast proliferation in a protease-activated receptor-2-dependent pathway., American Journal of Physiology. Lung Cellular and Molecular Physiology, Vol.290, No.2, 385-395, 2006.
(要約)
Human airway trypsin-like protease (HAT) was isolated from airway secretions and localized to bronchial epithelial cells by immunohistochemistry. In the present study, we examined whether HAT could stimulate DNA synthesis and proliferation of primary human bronchial fibroblasts (HBF). HAT significantly stimulated the proliferation of HBF by 20-55%, a level similar to that of the mitogenic activity of lung mast cell tryptase (MCT). HAT also stimulated the incorporation of [3H]thymidine in HBF, and this HAT-induced DNA synthesis was abolished by leupeptin. Protease-activated receptor-2 (PAR-2) mRNA was expressed and localized to the cell surface in HBF. PAR-2 activating peptide (AP) also enhanced DNA synthesis, and both HAT and PAR-2 AP induced receptor internalization, similar to the response to trypsin. Pretreatment of HBF with anti-PAR-2 antibody significantly suppressed both HAT and PAR-2 AP-induced DNA synthesis. In addition, HAT and PAR-2 AP induced intracellular Ca2+ mobilization in HBF. The HAT-induced increase in Ca2+ was desensitized by pretreatment with trypsin or PAR-2 AP. U0126, a specific MAPK inhibitor, completely inhibited HAT-induced DNA synthesis as well as HAT-induced phosphorylation of MAPK. The effect of HAT and MCT together was additive, whereas the effect of HAT and insulin together on HBF DNA synthesis was synergistic. These results indicate that HAT stimulates fibroblast proliferation in bronchial airways through a PAR-2-dependent MEK-MAPK mediated pathway and that HAT is linked to airway processes involving fibroblasts.
(キーワード)
trypsin-like protease / HAT / PAR--2 / bronchial fibroblasts
M Morishima, Nagakatsu Harada, S Hara, Atsuko Sano, Hiromasa Seno, Akira Takahashi, Yusuke Morita and Yutaka Nakaya : Monoamine Oxidase A Activity and Norepinephrine Level in Hippocampus Determine Hyperwheel Running in SPORTS Rats., Neuropsychopharmacology, Vol.31, No.12, 2627-2638, 2006.
(要約)
An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of alpha(2)-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of alpha(2)-adrenergic receptor antagonist yohimbine, but not of alpha(2)-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and alpha(2)-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.
Yutaka Nakaya, Y Hata, K Ishida, Akira Takahashi, Kyoko Morita and Kazuhito Rokutan : Approach to novel functional foods for stress control 2. Microarray assessment of exercise in healthy volunteers., The Journal of Medical Investigation : JMI, Vol.52, No.Suppl, 242-243, 2005.
(要約)
DNA microarray was used to measure stress response by exercise in peripheral blood leukocytes. Aerobic exercise did not alter mRNA pattern or urinary secretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Strenuous exercise increased urinary secretion of 8-OHdG and altered mRNA pattern in microarray. These results suggest that moderate exercise, i. e. aerobic exercise, did not show any change in 8-OHdG, an oxidative stress marker, or mRNA expression in the leukocytes, which might reflect whole body neurohormanal changes. In addition, strenuous exercise produced quite different expression pattern from those of psychological stress.
K Tsuchiya, I Kawamura, Akira Takahashi, T Nomura, C Kohda and M Mitsuyama : Listeriolysin O-induced membrane permeation mediates persistent IL-6 production in Caco-2 cells during Listeria monocytogenes infection in vitro., Infection and Immunity, Vol.73(7), No.7, 3869-3877, 2005.
(要約)
Listeriolysin O (LLO), a major virulence factor of Listeria monocytogenes, is a member of the cholesterol-dependent cytolysin family and plays important roles not only in survival of this bacterium in phagocytes but also in induction of various cellular responses, including cytokine production. In this work, we examined the involvement of LLO in induction of the cytokine response in intestinal epithelial cells, the front line of host defense against food-borne listeriosis. Infection of Caco-2 cells with wild-type L. monocytogenes induced persistent expression of interleukin-6 (IL-6) mRNA. In contrast, IL-6 expression was observed only transiently during infection with non-LLO-producing strains. A sublytic dose of recombinant LLO (rLLO) induced the expression of IL-6 via formation of membrane pores. Under conditions of LLO-induced pore formation without extensive cell lysis, Ca2+ influx was observed, and the IL-6 expression induced by rLLO was inhibited by pretreatment with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), an intracellular Ca2+ chelator. LLO secreted by cytoplasmic L. monocytogenes appeared to induce pore formation in the membrane and to enable the trafficking of intracellular and extracellular molecules. Pretreatment with BAPTA-AM inhibited persistent IL-6 expression in Caco-2 cells infected with wild-type L. monocytogenes. These results suggest that LLO is involved in IL-6 production in the late phase of infection through the formation of Ca2+-permeable pores and subsequent Ca2+-dependent modulation of signaling and gene expression.
Akira Takahashi, N Tanoue, M Nakano, A Hamamoto, K Okamoto, Y Fujii, Nagakatsu Harada and Yutaka Nakaya : A pore-forming toxin produced by Aeromonas sobria activates Ca2+ dependent Cl- secretion., Microbial Pathogenesis, Vol.38, No.4, 173-180, 2005.
(要約)
Bacteria produce many types of hemolysin that induce diarrhea by mechanisms that are not completely understood. Aeromonas sobria hemolysin (ASH) is a major virulence factor produced by A. sobria, a human pathogen that causes diarrhea. Since epithelial cells in the intestine are the primary targets of hemolysin, we investigated the effects of ASH on ion transport in human colonic epithelial (Caco-2) cells. ASH increased short-circuit currents (Isc) in a dose-dependent manner, and it also activated a 125I efflux from Caco-2 cells. ASH-induced Isc increases and 125I efflux activations were both suppressed by low Ca2+ levels in the extracellular solution or by pretreatment with the Ca2+ chlelator BAPTA-AM. Intracellular Ca2+ levels were increased by ASH in a biphasic fashion characterized by a rapid sharp increase (peak 1) followed by a sustained low plateau (peak 2). ASH-induced peak 1 was inhibited by pretreatment with pertussis toxin, indicating that Ca2+ was mobilized from intracellular stores, and peak 2 was induced by an influx of extracellular Ca2+. Peak 2 but not peak 1 was related to Cl- secretion. These results indicate that ASH activates Ca2+-dependent Cl- secretion.
Masaki Morishima-Yamato, Fumiko Hisaoka, Sachiko Shinomiya, Nagakatsu Harada, Akira Takahashi, Hideki Matoba and Yutaka Nakaya : Cloning and establishment of a line of rats for high levels of voluntary running, Life Sciences, Vol.77, No.5, 551-561, 2005.
(要約)
We generated an original Wistar line of rats that displayed increased levels of wheel running, which we named SPORTS (Spontaneously-Running-Tokushima-Shikoku). Male SPORTS rats ran voluntarily in a running wheel almost six times longer than male control Wistar rats, established without selection for their running activity. The running phenotype of female SPORTS rats was the same as female control Wistar rats. However, male offspring from the cross-mating between a female SPORTS rat and a male control rat also showed a similar level of hyper-running activity as the original SPORTS line. Compared to control rats, male SPORTS rats had lower levels of mean body weight, abdominal fat and plasma insulin after 4 weeks of running. It is likely that all these beneficial changes observed in the SPORTS rats reflected the increases in glucose disposal we observed in oral glucose tolerance tests carried out on the animals. We also found hyper-running caused a significant increase in skeletal muscle oxidative capacity, measured as the ratio of malate dehydrogenase to phosphofructokinase activity, an index of aerobic metabolism. These results indicate that the SPORTS rat may be a good animal model for determining the mechanisms responsible for up-regulation of running motivation, in addition to investigating changes in nutrient metabolism induced by high intensity exercise.
Naomi Tanoue, Akira Takahashi, Keinosuke Okamoto, Yoshio Fujii, Yutaka Taketani, Nagakatsu Harada, Masayuki Nakano and Yutaka Nakaya : A pore-forming toxin produced by Aeromonas sobria activates cAMP-dependent Cl- secretory pathways to cause diarrhea, FEMS Microbiology Letters, Vol.242, No.2, 195-201, 2005.
(要約)
Aeromonas sobria hemolysin (ASH) is one of the major virulence factors produced by A. sobria, a human pathogen that causes diarrhea. We investigated the effects of ASH on Cl(-) transport in human colonic epithelial cells. ASH increased short-circuit currents (Isc) and (125)I efflux from Caco-2 cells, indicating ASH activate Cl(-) secretion. Additions of inhibitors of cyclic AMP dependent Cl(-) channels, glybenclamide and NPPB suppressed the Isc and (125)I efflux increases induced by ASH. And ASH increased the intracellular cyclic AMP concentration. Moreover, ASH stimulated fluid accumulation in the iliac loop test, and glybenclamide and NPPB suppressed this fluid accumulation. Thus, cAMP-dependent Cl(-) secretory pathway could be related with diarrhea induced by A. sobria.
A Wada, A-P Wang, H Isomoto, I Satomi, T Takao, Akira Takahashi, S Awata, T Nomura, Y Fujii, S Kohno, K Okamoto, J-L J Millán Moss and T Hirayama : Placental and intestinal alkaline phosphatases are receptors for Aeromonas sobria hemolysin, International Journal of Medical Microbiology, Vol.294, No.7, 427-435, 2005.
(要約)
The Aeromonas sobria hemolysin causes diarrhea following infection by this enteropathogenic bacterium. We previously identified the putative receptor for A. sobria hemolysin as a p66 protein on Intestine 407 cells (Microb. Pathog. 27 (1999) 215-221). Here, we have partially purified and obtained a peptide mass fingerprint of p66 which revealed its identity with placental alkaline phosphatase (PLAP). Recombinant PLAP expressed in 293T cells was also found to bind to hemolysin and the binding was found not to be dependent on the N-linked glycosylation of PLAP. By immunohistochemical analysis, PLAP expression was detected in human intestinal mucosa, the target tissue in disease. In addition to PLAP, hemolysin also binds to intestinal alkaline phosphatase (IAP), an enzyme that is also abundantly expressed in intestine. Thus, both PLAP and IAP are very likely involved in the pathogenesis of diarrhea caused by this bacterial toxin.
Ketamine inhibits adenosine triphosphate-sensitive potassium (KATP) channels, which results in the blocking of ischemic preconditioning in the heart and inhibition of vasorelaxation induced by KATP channel openers. In the current study, the authors investigated the molecular mechanisms of ketamine's actions on sarcolemmal KATP channels that are reassociated by expressed subunits, inwardly rectifying potassium channels (Kir6.1 or Kir6.2) and sulfonylurea receptors (SUR1, SUR2A, or SUR2B). The authors used inside-out patch clamp configurations to investigate the effects of ketamine on the activities of reassociated Kir6.0/SUR channels containing wild-type, mutant, or chimeric SURs expressed in COS-7 cells. Ketamine racemate inhibited the activities of the reassociated KATP channels in a SUR subtype-dependent manner: SUR2A/Kir6.2 (IC50 = 83 microM), SUR2B/Kir6.1 (IC50 = 77 microM), SUR2B/Kir6.2 (IC50 = 89 microM), and SUR1/Kir6.2 (IC50 = 1487 microM). S-(+)-ketamine was significantly less potent than ketamine racemate in blocking all types of reassociated KATP channels. The ketamine racemate and S-(+)-ketamine both inhibited channel currents of the truncated isoform of Kir6.2 (Kir6.2DeltaC36) with very low affinity. Application of 100 mum magnesium adenosine diphosphate significantly enhanced the inhibitory potency of ketamine racemate. The last transmembrane domain of SUR2 was essential for the full inhibitory effect of ketamine racemate. These results suggest that ketamine-induced inhibition of sarcolemmal KATP channels is mediated by the SUR subunit. These inhibitory effects of ketamine exhibit specificity for cardiovascular KATP channels, at least some degree of stereoselectivity, and interaction with intracellular magnesium adenosine diphosphate.
Kazuaki Mawatari, Kakui Sae, Nagakatsu Harada, Takamasa Ohnishi, Yasuharu Niwa, Kazuko Okada, Akira Takahashi, Keisuke Izumi and Yutaka Nakaya : Endothelin-1(1 31) levels are increased in atherosclerotic lesions of the thoracic aorta of hypercholesterolemic hamsters, Atherosclerosis, Vol.175, No.2, 203-212, 2004.
(要約)
The novel vaso-constricting 31-amino acid-length endothelin-1 [ET-1(1-31)] is selectively produced by human mast cell chymase via its action on big ET-1. However, the pathological role of ET-1(1-31) in atherosclerosis remains unclear. The aim of this study was to clarify vasoconstrictive response and expression of ET-1(1-31) in atherosclerotic aorta. Syrian golden hamster, was used for preparing the atherosclerotic models by the administration of a high cholesterol diet (HC), treatment with the nitric oxide synthase inhibitor (Nomega-nitro-L-arginine methylester, L-NAME) alone, or both (HC and L-NAME) for 40 weeks. Early atherosclerosis was observed in the case of HC or L-NAME alone treatments respectively and severe atherosclerosis was observed in the case of combined HC and L-NAME treatment. Vasoconstriction induced by ET-1(1-31) was not altered by the atherosclerotic changes, but the expression pattern of ET-1(1-31) was different at each stage of the atherosclerotic aorta. ET-1(1-31) was observed rarely in normal aortas or in early atherosclerotic lesions, but ET-1(1-31) expression was dramatically increased in aortic neointima and adventitia in a state of atherosclerosis with severe inflammation. ET-1(1-31) might play in a role of promoting atherosclerosis, and especially be involved in inflammatory mediation during the progression of atherosclerosis.
Takashi Kawano, Shuzo Oshita, Akira Takahashi, Yasuo Tsutsumi, Yoshinobu Tomiyama, Hiroshi Kitahata, Yasuhiro Kuroda and Yutaka Nakaya : Molecular Mechanisms of the Inhibitory Effects of Bupivacaine, Levobupivacaine, and Ropivacaine on Sarcolemmal Adenosine Triphosphate-sensitive Potassium Channels in the Cardiovascular System., Anesthesiology, Vol.101, No.2, 390-398, 2004.
(要約)
Sarcolemmal adenosine triphosphate-sensitive potassium (KATP) channels in the cardiovascular system may be involved in bupivacaine-induced cardiovascular toxicity. The authors investigated the effects of local anesthetics on the activity of reconstituted KATP channels encoded by inwardly rectifying potassium channel (Kir6.0) and sulfonylurea receptor (SUR) subunits. The authors used an inside-out patch clamp configuration to investigate the effects of bupivacaine, levobupivacaine, and ropivacaine on the activity of reconstituted KATP channels expressed in COS-7 cells and containing wild-type, mutant, or chimeric SURs. Bupivacaine inhibited the activities of cardiac KATP channels (IC50 = 52 microm) stereoselectively (levobupivacaine, IC50 = 168 microm; ropivacaine, IC50 = 249 microm). Local anesthetics also inhibited the activities of channels formed by the truncated isoform of Kir6.2 (Kir6.2 delta C36) stereoselectively. Mutations in the cytosolic end of the second transmembrane domain of Kir6.2 markedly decreased both the local anesthetics' affinity and stereoselectivity. The local anesthetics blocked cardiac KATP channels with approximately eightfold higher potency than vascular KATP channels; the potency depended on the SUR subtype. The 42 amino acid residues at the C-terminal tail of SUR2A, but not SUR1 or SUR2B, enhanced the inhibitory effect of bupivacaine on the Kir6.0 subunit. Inhibitory effects of local anesthetics on KATP channels in the cardiovascular system are (1) stereoselective: bupivacaine was more potent than levobupivacaine and ropivacaine; and (2) tissue specific: local anesthetics blocked cardiac KATP channels more potently than vascular KATP channels, via the intracellular pore mouth of the Kir6.0 subunit and the 42 amino acids at the C-terminal tail of the SUR2A subunit, respectively.
Nagakatsu Harada, Chika Ninomiya, Yoshie Osako, Masaki Morishima, Kazuaki Mawatari, Akira Takahashi and Yutaka Nakaya : Taurine alters respiratory gas exchange and nutrient metabolism in type 2, Obesity Research, Vol.12, No.7, 1077-1084, 2004.
(要約)
To assess the effect of taurine supplementation on respiratory gas exchange, which might reflect the improved metabolism of glucose and/or lipid in the type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Male OLETF rats (16 weeks of age) were randomly divided into two groups: unsupplemented group and taurine-supplemented (3% in drinking water) group. After 9 weeks of treatment, indirect calorimetry and insulin tolerance tests were conducted. The amounts of visceral fat pads, tissue glycogen, the blood concentrations of glucose, triacylglycerol, taurine, and electrolytes, and the level of hematocrit were compared between groups. A nondiabetic rat strain (Long-Evans Tokushima Otsuka) was used as the age-matched normal control. The indirect calorimetry showed that the treatment of OLETF rats with taurine could reduce a part of postprandial glucose oxidation possibly responsible for the increase of triacylglycerol synthesis in the body. Taurine supplementation also improved hyperglycemia and insulin resistance and increased muscle glycogen content in the OLETF rats. Supplementation with taurine increased the blood concentration of taurine and electrolyte and fluid volume, all of which were considered to be related to the improvement of metabolic disturbance in OLETF rats. Taurine supplementation may be an effective treatment for glucose intolerance and fat/lipid accumulation observed in type 2 diabetes associated with obesity. These metabolic changes might be ascribed, in part, to the alteration of circulating blood profiles, where the improved hyperglycemia and/or the blood accumulation of taurine itself would play roles.
Takashi Kawano, Shuzo Oshita, Akira Takahashi, Yasuo Tsutsumi, Yoshinobu Tomiyama, Hiroshi Kitahata, Yasuhiro Kuroda and Yutaka Nakaya : Molecular mechanisms of the inhibitory effects of propofol and thiamylal on sarcolemmal adenosine triphosphate-sensitive potassium channels., Anesthesiology, Vol.100, No.2, 338-346, 2004.
(要約)
Both propofol and thiamylal inhibit adenosine triphosphate-sensitive potassium (KATP) channels. In the current study, the authors investigated the effects of these anesthetics on the activity of recombinant sarcolemmal KATP channels encoded by inwardly rectifying potassium channel (Kir6.1 or Kir6.2) genes and sulfonylurea receptor (SUR1, SUR2A, or SUR2B) genes. The authors used inside-out patch clamp configurations to investigate the effects of propofol and thiamylal on the activity of recombinant KATP channels using COS-7 cells transfected with various types of KATP channel subunits. Propofol inhibited the activities of the SUR1/Kir6.2 (EC50 = 77 microm), SUR2A/Kir6.2 (EC50 = 72 microm), and SUR2B/Kir6.2 (EC50 = 71 microm) channels but had no significant effects on the SUR2B/Kir6.1 channels. Propofol inhibited the truncated isoform of Kir6.2 (Kir6.2DeltaC36) channels (EC50 = 78 microm) that can form functional KATP channels in the absence of SUR molecules. Furthermore, the authors identified two distinct mutations R31E (arginine residue at position 31 to glutamic acid) and K185Q (lysine residue at position 185 to glutamine) of the Kir6.2DeltaC36 channel that significantly reduce the inhibition of propofol. In contrast, thiamylal inhibited the SUR1/Kir6.2 (EC50 = 541 microm), SUR2A/Kir6.2 (EC50 = 248 microm), SUR2B/Kir6.2 (EC50 = 183 microm), SUR2B/Kir6.1 (EC50 = 170 microm), and Kir6.2DeltaC36 channels (EC50 = 719 microm). None of the mutants significantly affects the sensitivity of thiamylal. These results suggest that the major effects of both propofol and thiamylal on KATP channel activity are mediated via the Kir6.2 subunit. Site-directed mutagenesis study suggests that propofol and thiamylal may influence Kir6.2 activity by different molecular mechanisms; in thiamylal, the SUR subunit seems to modulate anesthetic sensitivity.
Sae Kakui, Kazuaki Mawatari, Takamasa Ohnishi, Yasuharu Niwa, Naomi Tanoue, Nagakatsu Harada, Akira Takahashi, Keisuke Izumi and Yutaka Nakaya : Localization of the 31-amino-acid endothelin-1 in hamster tissue, Life Sciences, Vol.74, No.11, 1435-1443, 2004.
(要約)
Endothelin (ET)-1(1-31) is a novel vasoconstrictor peptide produced by human mast cell chymase, which selectively cleaves big ET-1 at the Try(31)-Gly(32) bond. We investigated the localization of ET-1(1-31) in various hamster tissues by immunohistochemistry and compared it to the distribution of ET-1(1-21). We found that the localization and amount of ET-1(1-31) were different from those of ET-1(1-21) in each tissue. ET-1(1-31)-like immunoreactivities (IR) in the heart, lung, and adrenal gland were observed in the same areas as ET-1(1-21) but were significantly weaker, suggesting that ET-1(1-31) might play a role only in mast cell/chymase-related pathological conditions in these tissues. In the liver, ET-1(1-31)-like IR was strongly detected in Kupffer cells where ET-1(1-21)-like IR was seen more weakly. In the kidney, ET-1(1-31)-like IR was slightly higher than ET-1(1-21). These results suggest that ET-1(1-31) might have physiological roles distinct from those of ET-1(1-21) in some hamster tissues.
S Manabe, I Kuroda, Kazuko Okada, Masaki Morishima, Nagakatsu Harada, Akira Takahashi, K Sasaki and Yutaka Nakaya : Decreased blood levels of lactic acid and urinary excretion of 3-methylhistidine after exercise by chronic taurine treatment in rats, Journal of Nutritional Science and Vitaminology, Vol.49, No.6, 375-380, 2003.
(要約)
Taurine is reported to increase contractility of skeletal muscle and cardiac myocyte, which can increase exercise performance. The present study aimed to clarify taurine's effect on chronic endurance exercise, especially accumulation of lactic acid (LA), a marker of fatigue and ability of aerobic exercise, and urinary secretion of 3-methylhistidine (3-MH), a marker of muscle breakdown in rats. After exercise blood levels of LA and urinary excretion of 3-MH were significantly increased and this increase was significantly less in those with chronic treatment of taurine. Taurine treatment also significantly decreased fat accumulation and blood levels of cholesterol and triglyceride, which might improve insulin resistance and utilization of fat and glucose. These results indicate taurine treatment is useful for reducing physical fatigue and muscle damage during exercise training in rats, presumably due to antioxidant property and improvement of muscle and cardiac functions by taurine.
Mari Miki, Yoichi Nakamura, Akira Takahashi, Yutaka Nakaya, Hiroshi Eguchi, Tsukio Masegi, Kazuo Yoneda, Susumu Yasuoka and Saburo Sone : Effect of human airway trypsin-like protease on intracellular free Ca2+ concentration in human bronchial epithelial cells, The Journal of Medical Investigation : JMI, Vol.50, No.1-2, 95-107, 2003.
(要約)
It has been shown that human airway trypsin-like protease (HAT) is localized in human bronchial epithelial cells (HBEC), and trypsin activates protease-activated receptor-2 (PAR-2). Activation of PAR-2 activates G-protein followed by an increase of intracellular free Ca2+, [Ca2+]in. This study was undertaken to clarify whether HAT can activate PAR-2 in HBEC or not. RT-PCR showed that HAT mRNA is expressed in HBEC, and PAR-2 mRNA is the most strongly expressed of the known PARs in HBEC. Both PAR-2 agonist peptide (PAR-2 AP) and HAT increased [Ca2+]in in HBEC in a biphasic fashion; a prompt, sharp increase (peak I) and a sustained low plateau (peak II). PAR-2 AP over 100-200 microM and HAT over 200-300 mU/ml (0.08-0.12 microM) induced both peak I and II, and PAR-2 AP below 100 microM and HAT below 200 mU/ml induced only peak II. Both PAR-2 AP-induced and HAT-induced peak I were induced by Ca2+ mobilization from intracellular stores, because they appeared even in Ca2+-free medium. Both PAR-2 AP-induced and HAT-induced peak II were induced by an influx of extracellular Ca2+, because they were abolished in Ca2+-free medium. The Ca2+ response to HAT was desensitized by exposure of HBEC to PAR-2 AP. These results indicate that HBEC have a functional PAR-2, and HAT regulates cellular functions of HBEC via activation of PAR-2.
Yutaka Nakaya, Nagakatsu Harada, Sae Kakui, Kazuko Okada, Akira Takahashi, Junnya Inoi and Susumu Ito : Severe catabolic state after prolonged fasting in cirrhotic patients: effect of oral branched-chain amino-acid-enriched nutrient mixture, Journal of Gastroenterology, Vol.37, No.7, 531-536, 2002.
(要約)
Cirrhotic patients frequently undergo various medical procedures, such as diagnostic gastrointestinal endoscopy, without taking breakfast. The aim of the present study was to clarify the effect of longer fasting (> 12 h) on energy metabolism, and to test whether supplementation of an oral branched-chain amino-acid-enriched nutrient mixture (BCAA mixture), which contains various nutrients in addition to BCAA, could improve the catabolic state. Metabolic measurement was performed in 30 cirrhotic patients and 13 normal subjects, using indirect calorimetry. Compared with that in the normal subjects, the respiratory quotient (RQ) was significantly lower after an overnight fast in the cirrhotic patients, indicating accelerated fat oxidation and a catabolic state. In addition, RQ in cirrhotic patients (n = 7) decreased rapidly with longer fasting, whereas that in the normal subjects (n = 5) showed relatively stable values. These results indicate that special care should be taken with medical procedures that are carried out in patients who have fasted. The effect of oral glucose, a carbohydrate-rich snack (rice ball), and the BCAA mixture (each, 210 kcal) on RQ was studied in 6 normal subjects and 6 patients with liver cirrhosis after an overnight fast. Supplementation of the carbohydrate-rich snack and the BCAA mixture (210 kcal each) elevated RQ and blood glucose levels to a similar degree in the cirrhotic patients. Oral administration of glucose (210 kcal) led to significantly greater elevation of blood glucose levels than the other snacks, which may be unfavorable for cirrhotic patients, who frequently have glucose intolerance. In the 30 cirrhotic patients, supplementation with the BCAA mixture in the late evening significantly improved RQ in the early morning. Carbohydrate-rich meals are used as a late evening snack in cirrhotic patients, but our study indicates that supplementation with a BCAA mixture can also be used to reduce fat oxidation in the early morning, with results similar to those with carbohydrate-rich snacks.
Manabu Kinoshita, Yutaka Nakaya, Nagakatsu Harada, Akira Takahashi, Masahiro Nomura and Shigenobu Bando : Combination Therapy of Exercise and Angiotensin-Converting Enzyme Inhibitor Markedly Improves Insulin Sensitivities in Hypertensive Patients With Insulin Resistance, Circulation Journal, Vol.66, No.7, 655-658, 2002.
(要約)
The contraction of muscle enhances the release of bradykinin (BK) and improves glucose uptake by the muscle. Angiotensin-converting enzyme inhibitor (ACEI) slows the breakdown of BK, thus the effect of BK is augmented in the presence of ACEI. The present study investigated whether the combination of exercise (increased production of BK) and ACEI (delay in breakdown of BK) might further improve insulin sensitivity in hypertensive patients with insulin resistance (HOMA-R>1.8). Patients were assigned either to increased walking distance (Walking group) or taking 2mg remocapril, an ACEI, daily (ACEI group) for 8 weeks. Then both interventions were given to all patients for 8 weeks (ACEI+Walking group). Blood concentrations of triglycerides were slightly lower in the ACEI+Walking group than at baseline, although there were no significant differences in total cholesterol or high density lipoprotein-cholesterol among the 2 groups. Blood glucose was not significantly different with each treatment, but blood concentrations of insulin and HOMA-R were significantly lower in the Walking and ACEI groups compared with the Control group. The combination of walking and ACEI further lowered blood concentrations of insulin and HOMA-R, which suggests that this treatment is beneficial for hypertensive patients with insulin resistance.
Takashi Kawano, Shuzo Oshita, Yasuo Tsutsumi, Yoshinobu Tomiyama, Hiroshi Kitahata, Yasuhiro Kuroda, Akira Takahashi and Yutaka Nakaya : Clinically relevant concentrations of propofol have no effect on adenosine triphosphate-sensitive potassium channels in rat ventricular myocytes., Anesthesiology, Vol.96, No.6, 1472-1477, 2002.
(要約)
Activation of adenosine triphosphate-sensitive potassium (K(ATP)) channels produces cardioprotective effects during ischemia. Because propofol is often used in patients who have coronary artery disease undergoing a wide variety of surgical procedures, it is important to evaluate the direct effects of propofol on K(ATP) channel activities in ventricular myocardium during ischemia. The effects of propofol (0.4-60.1 microg/ml) on both sarcolemmal and mitochondrial K(ATP) channel activities were investigated in single, quiescent rat ventricular myocytes. Membrane currents were recorded using cell-attached and inside-out patch clamp configurations. Flavoprotein fluorescence was measured to evaluate mitochondrial oxidation mediated by mitochondrial K(ATP) channels. In the cell-attached configuration, open probability of K(ATP) channels was reduced by propofol in a concentration-dependent manner (EC(50) = 14.2 microg/ml). In the inside-out configurations, propofol inhibited K(ATP) channel activities without changing the single-channel conductance (EC(50) = 11.4 microg/ml). Propofol reduced mitochondrial oxidation in a concentration-dependent manner with an EC(50) of 14.6 microg/ml. Propofol had no effect on the sarcolemmal K(ATP) channel activities in patch clamp configurations and the mitochondrial flavoprotein fluorescence induced by diazoxide at clinically relevant concentrations (< 2 microm), whereas it significantly inhibited both K(ATP) channel activities at very high, nonclinical concentrations (> 5.6 microg/ml; 31 microm).
Akira Takahashi, Wada Akihiro, Ogushi Ken-ichi, Maeda Kyoko, Kawahara Tsukasa, Kazuaki Mawatari, Hisao Kurazono, Moss Joel, Hirayama Toshiya and Yutaka Nakaya : Production of L-defensin-2 by human colonic epithelial cells induced by Salmonella enteritidis flagella filament structural protein, FEBS Letters, Vol.508, No.3, 484-488, 2001.
(要約)
We recently showed that FliC of Salmonella enteritidis increased human beta-defensin-2 (hBD-2) expression, and now describe the signaling responsible pathway. FliC increased the intracellular Ca(2+) concentration ([Ca(2+)](in)) in Caco-2 cells. The [Ca(2+)](in) increase induced by FliC was prevented by U73122 and heparin, but not by chelating extracellular Ca(2+) or pertussis toxin. The FliC-induced increase in hBD-2 promoter activity via nuclear factor kappaB (NF-kappaB) was also inhibited by chelation of intracellular Ca(2+) or by U73122. We conclude that FliC increased [Ca(2+)](in) via inositol 1,4,5-trisphosphate, which was followed by up-regulating hBD-2 mRNA expression via an NF-kappaB-dependent pathway.
Akira Takahashi, Toshitaka Ikehara, Keiko Hosokawa and Hisao Yamaguchi : Properties of Ca2+-dependent K+ channels of human gingival fibroblasts, Journal of Dental Research, Vol.74, No.8, 1507-1512, 1995.
122.
Zhen-Lin Jiang, Hisao Yamaguchi, Hiroyuki Tanaka, Akira Takahashi, Shingo Tanabe, Noboru Utsuyama, Toshitaka Ikehara, Keiko Hosokawa, Yohsuke Kinouchi and Hiroshi Miyamoto : Blood flow velocity in the commom carotid artery in humans during graded exercise on a treadmill, Europian Journal of Physiology, Vol.70, 234-239, 1995.
123.
Jufang He, Lin Zen Jiang, Hiroyuki Tanaka, Toshitaka Ikehara, Akira Takahashi, Hisao Yamaguchi, Hiroshi Miyamoto, Tadamitsu Iritani and Yohsuke Kinouchi : Changes in caritid blood flow and electrocardiogram in humans during and after walking on a treadmill, European Journal of Applied Physiology and Occupational Physiology, Vol.67, No.6, 486-491, 1993.
(要約)
Blood flow velocity in the common carotid artery and the electrocardiogram were measured simultaneously by telemetry in seven male subjects during 20-min walking on a treadmill at an exercise intensity corresponding to a mean oxygen uptake of 26.0 (SD 2.9) ml.kg-1.min-1. The mean cardiac cycle was shortened from 0.814 (SD 0.103) s to 0.452 (SD 0.054) s during this exercise. Of this shortening, 73% was due to shortening of the diastolic period and 27% to shortening of the systolic period. In the relatively small shortening of the mean systolic period [from 0.377 (SD 0.043) s to 0.268 (SD 0.029) s], the isovolumetric contraction time was shortened by 56%. During exercise, the heart rate (fc) increased by 79.4% [from 74.3 (SD 9.3) beats.min-1 to 133.3 (SD 14.8) beats.min-1], and the peak blood velocity (S1) in the common carotid artery increased by 56.1% [from 0.82 (SD 0.10) m.s-1 to 1.28 (SD 0.11) m.s-1]. After exercise, the S1 decreased rapidly to the resting level. The fc decreased more slowly, still being higher than the initial resting level 5 min after exercise. The diastolic velocity wave and the end-diastolic foot decreased during exercise. The blood flow rate in the carotid artery increased transiently by 13.5% at the beginning of exercise [from 5.62 (SD 0.63) ml.s-1 to 6.38 (SD 0.85) ml.s-1] and by 26.5% at the end of the exercise period [from 5.62 (SD 0.63) ml.s-1 to 7.11 (SD 1.34) ml.s-1].(ABSTRACT TRUNCATED AT 250 WORDS)
(キーワード)
Adult / Blood Pressure / Carotid Artery, Common / Electrocardiography / Exercise / Exercise Test / Heart Rate / Humans / Male / Oxygen Consumption / Regional Blood Flow / Time Factors / Walking
Hisao Yamaguchi, Keiko Hosokawa, Zheng-Lin Jiang, Akira Takahashi, Toshitaka Ikehara and Hiroshi Miyamoto : Arrest of cell cycle progression of HeLa cells in the early G1 phase in K +-depleted conditions abd its recovery upon addition of insulin and LDL, Journal of Cellular Biochemistry, Vol.53, No.1, 13-20, 1993.
125.
Toshitaka Ikehara, Hisao Yamaguchi, Keiko Hosokawa, Akira Takahashi and Hiroshi Miyamoto : Kinetic study on the effects of intracellular K+ and Na+ on Na+,K+,Cl- cotransport of HeLa cells by Rb+ influx determination, The Journal of Membrane Biology, Vol.132, 115-124, 1993.
Hiroki Mori, Yuji Morine, Kazuaki Mawatari, Ayumi Chiba, Shin-ichiro Yamada, Yu Saitou, Hiroki Ishibashi, Akira Takahashi and Mitsuo Shimada : Bile Metabolites and Risk of Carcinogenesis in Patients With Pancreaticobiliary Maljunction: A Pilot Study., Anticancer Research, Vol.41, No.1, 327-334, 2021.
(要約)
Pancreaticobiliary maljunction (PBM), a disease with reflux of pancreatic and bile juice in the pancreaticobiliary tract, is a high-risk factor for biliary tract cancer. The aim of this study was to investigate the mechanism of carcinogenesis in PBM using a metabolomics analysis of bile sampled during surgery. Three patients with PBM without biliary tract cancer, four patients with extrahepatic bile duct cancer (EHBC), and three controls with benign disease were enrolled. Metabolomics analysis of bile samples was performed using capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry to discriminate the amino acid and lipidomic profiles. The principal component analysis in the capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry revealed similar metabolites in patients with PBM and those with EHBC; furthermore, there was a clear difference between patients with PBM or EHBC compared to controls. The amino acid profiles revealed the following 20 potential carcinogenic candidates for PBM: isoleucine, phenylalanine, tyrosine, leucine, tryptophan, arginine, lysine, valine, asparagine, methionine, aspartic acid, serine, threonine, histidine, glutamine, alanine, proline, glutamic acid, and pyruvic acid. The lipidomic profiles revealed the following 11 carcinogenic candidates: lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidyl glycerol, lysophosphatidyl glycerol, triacylglycerol, diacylglycerol, ceramide, sphyngomyeline, fatty acid, hyperforin, and vitamin D. Among these characteristic metabolites, the branched-chain amino acids, methionine and lysophosphatidylcholine are known to be related to carcinogenesis. The bile metabolites were extremely similar in patients with PBM and those with EHBC. Furthermore, amino acid and lipid metabolism was markedly different in patients with PBM or EHBC compared to healthy controls.
(キーワード)
Bile / Bile Duct Neoplasms / Cell Transformation, Neoplastic / Chromatography, Liquid / Disease Susceptibility / Electrophoresis, Capillary / Female / Humans / Male / Mass Spectrometry / Metabolomics / Pancreaticobiliary Maljunction / Pilot Projects / Risk Assessment / Risk Factors
Noriko Matsumoto, Kouzou Yoshikawa, Mitsuo Shimada, Nobuhiro Kurita, Horohiko Sato, Takashi Iwata, Jun Higashijima, Motoya Chikakiyo, Masaaki Nishi, Hideya Kashihara, Chie Takasu, Shohei Eto, Akira Takahashi, Masatake Akutagawa and Takahiro Emoto : Effect of light irradiation by light emitting diode on colon cancer cells., Anticancer Research, Vol.34, No.9, 4709-4716, 2014.
(要約)
Recent studies have demonstrated the efficacy of irradiation from light emitting diodes (LED) for wound healing, anti-inflammation and anticancer therapies. However, little is known about the effects of visible light in colon cancer cells. The purpose of this study was to evaluate the biological response (including gene expression changes) of human colon cancer cells to different wavelengths of LED irradiation. Human colon cancer cells (HT29 or HCT116) were seeded onto laboratory dishes that were then put on LED irradiation equipment with a 465 nm-, 525 nm-, or 635 nm-LED. Irradiation at 15 or 30 mW was performed 10 min/day, each day for 5 days. The cell counting kit8 was then used to measure cell viability. Apoptosis and expression of several mRNAs (caspase, MAPK and autophagy pathway) in HT29 cultures irradiated with 465 nm LED were evaluated via AnnexinV/PI and RT-PCR, respectively. Viability of HT29 and HCT116 cells was lower in 465 nm-LED irradiated cultures than in control cultures, but viability of HT29 cells did not differ between control cultures and 525 nm-LED or 635 nm-LED irradiated cultures. Moreover, the expression of FAS, caspase-3, capase-8, and JUK were significantly higher in 465 nm-LED irradiated cultures than in control cultures, and expression of ERK1/2 and LC3 was lower in blue-irradiated cells. LED irradiation at 465 nm inhibited the proliferation of HT29 cells and of HCT116 cells. Notably, LED irradiation at 465 nm promoted apoptosis inHT29 cultures via the extrinsic apoptosis pathway and the MAPK pathway.
Metabolic syndrome includes abdominal obesity, hyperlipidemia, diabetes, and hypertension. All, but hypertension, are obviously related to metabolism. However, hypertension might result from, at least in part, abdominal obesity, because adipose tissue produces bioactive mediators (adipocytokines)which increase blood pressure. In treatment of hypertension, we should concern insulin resistance, which is a major risk factor of cardiovascular events. Angiotensin converting enzyme inhibitor is known to improve insulin resistance, but results of angiotensin receptor blocker in animal studies are controversial. In clinical trial, there are many established data that ARBs prevent new onset of diabetes mellitus, suggesting that this agent also has a beneficial effect on glucose metabolism. Short acting Ca-antagonists, such as nifedipine, decrease insulin sensitivity, but long-acting Ca-antagonists increase it. βblockers decrease insulin sensitivity but those with α-blocking action improve insulin resistance. Recent study, ARB is more potent to reduce cardiovascular risk in those with obesity than in those with normal body weight, suggesting some drugs are more effective in metabolic syndrome. Thus, when we chose antihypertensive drugs in treating patients with metabolic syndrome, we have to choose proper drugs in addition to modify life-style.
Yutaka Nakaya, Kazuaki Mawatari, Akira Takahashi, Nagakatsu Harada, Hata Akiko and Yasui Sonoko : The phytoestrogen ginsensoside Re activates potassium channels of vascular smooth muscle cells through PI3K/Akt and nitric oxide pathways, The Journal of Medical Investigation : JMI, Vol.54, No.3,4, 381-384, Aug. 2007.
(要約)
In vascular smooth muscle cells, large-conductance Ca(2+)-activated K(+) channels (K(Ca) channels) play a pivotal role in determining membrane potential, and thereby the vascular tone. Ginsenoside Re, a phytochemical from ginseng, is reported to activate this channel, but its precise mechanism is unsolved. Patch clamp studies showed that ginsenoside Re activates K(Ca) channels in the arterial smooth muscle cell line A10 in a dose-dependent manner. The channel-opening effect of ginsenoside Re was inhibited by 1 microM L-NIO, an inhibitor of eNOS, but not by 3 microM SMTC, an inhibitor of nNOS, indicating that ginsenoside Re activated K(Ca) channels through activation of eNOS. SH-6 (10 microM), an Akt inhibitor, and wortmannin, a PI3-kinase inhibitor, completely blocked activation of K(Ca) channels by ginsenoside Re, indicating that it activates eNOS via a c-Src/PI3-kinase/Akt-dependent mechanism. In addition, the ginsenoside Re-induced activation of eNOS and K(Ca) channel was blocked by 10 microM ICI 182, 780, an inhibitor of membrane estrogen receptor-alpha, suggesting that eNOS activation occurs via a non-genomic pathway of this receptor. In conclusion, ginsenoside Re releases NO via a membrane sex steroid receptors, resulting in K(Ca) channel activation in vascular smooth muscle cells, promoting vasodilation and preventing severe arterial contraction.
Shintaro Inoue, Takahito Watanabe, FUJIE Kai, SHIMAMURA Ayane, Yoshiyasu Ishimaru, Katsuyuki Miyawaki, Akira Takahashi, Takeshi Nikawa and Taro Mito : Melanin pigmentation is regulated via dopamine competition with the sclerotin biosynthesis pathway in the cuticle of hemimetabolous insects, The XXVII International Congress of Entomology 2024, Kyoto, Japan, Aug. 2024.
2.
Takeshi Nikawa, Katsuyuki Miyawaki, Akira Takahashi, Takahito Watanabe and Taro Mito : ANTI-MUSCLE ATROPHIC PROTEIN FOOD SOURCE IN SPACE: DEVELOPMENT OF A RECIRCULATORY REARING SYSTEM FOR SOYBEANS AND CRICKETS, 45th COSPAR Scientific Assembly-COSPAR 2024, Jul. 2024.
3.
Kai Ishida, Takaaki Shimohata, Kanda Yuna, Nguyen Quoc Anh, Masuda Rumiko, Yamazaki Kohei, Takashi Uebanso, Kazuaki Mawatari, Kashimoto Takashige and Akira Takahashi : Characteristic metabolic changes in the infected tissue due to Vibrio vulnificus in a wound infection model., 57th United States Japan Cooperative Medical Science Program Joint Panel Conference on Cholera and Other Bacterial Enteric Infections, Dec. 2023.
4.
SHINODA Koichi, Kazuaki Mawatari, Bui K. N. T., Hirakawa H., Awamoto K., Wakitani M, Shinoda T. and Akira Takahashi : Development of novel far-UVC light source for high germicidal effects and low human health risk., 2023 IEEE Photonics Conference, Orlando, Nov. 2023.
5.
Akira Takahashi, Katsuyuki Miyawaki, Kazuaki Mawatari, Takeshi Nikawa, Mutsumi Aihara, Fukushima Shiho, Akizawa Shinta, Yamashita Michiyo and Koi Yumena : Development of closed-circulation soybean cultivation system applicable to extreme environments, The 3rd Japan-France International Symposium on Space Nutrition/Medicine, Kyoto, Nov. 2023.
6.
Shintaro Inoue, Takahito Watanabe, Hamaguchi Taiki, Fujie Kai, Shimamura Ayane, Yoshiyasu Ishimaru, Katsuyuki Miyawaki, Takeshi Nikawa, Akira Takahashi, Sumihare Noji and Taro Mito : Artificial modification of cricket body color: breeding for the next-generation of protein supply, International Conference of Non-Traditional Arthropod Model Systems, Aug. 2023.
7.
Fujie Kai, Shintaro Inoue, Hamaguchi Taiki, Yoshiyasu Ishimaru, Katsuyuki Miyawaki, Takeshi Nikawa, Akira Takahashi, Sumihare Noji, Takahito Watanabe and Taro Mito : The discovery of two paralogous dopamine-synthase genes in the two-spotted cricket Gryllus bimaculatus, International Conference of Non-Traditional Arthropod Model Systems, Aug. 2023.
8.
Onoda Yushi, Kai Ishida, Kadomura-Ishikawa Yasuko, Nagahashi Miharu, Yamashita Michiyo, Fukushima Shiho, Aizawa Toshihiko, Yamauchi Shigeharu, Fujikawa Yasuo, Tanaka Tomotake, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Investigation of the wavelength dependence of fungal inactivation by standardized UV-LED irradiation device, The 10th Congress of European Microbiologists FEMS 2023, Hamburg, Jul. 2023.
9.
Kai Ishida, Takaaki Shimohata, Kanda Yuna, Nguyen Quoc Anh, Masuda Rumiko, Yamazaki Kohei, Takashi Uebanso, Kazuaki Mawatari, Kashimoto Takashige and Akira Takahashi : Characteristic metabolic changes in the infected tissue due to Vibrio vulnificus in a wound infection model, 日米コレラ部会(日米医学協力研究会コレラ・細菌性腸管感染症専門部会), Jul. 2023.
10.
SHINODA Koichi, NGAN THI KIM BUI, Kazuaki Mawatari, HIRAKAWA H., AWAMOTO K., Wakitani M., SHINODA T. and Akira Takahashi : Application Of Far-UVC Radiation For Sterilization Using New Strategies To Reduce Human Health Risks And Environmental Loads, ASM Microbe 2023, Houston, Jun. 2023.
11.
Kai Ishida, Onoda Yushi, Yasuko Ishikawa, Nagahashi Miharu, Yamashita Michiyo, Fukushima S., Aizawa T., Yamauchi S., Fujikawa Y., Tanaka T., Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Evaluation of wavelength dependent inactivation of bacteria, viruses, and fungi by originally developed light source with UV-LEDs, ASM Microbe 2023, Houston, Jun. 2023.
12.
NGAN THI KIM BUI, SHINODA Koichi, Kazuaki Mawatari, HIRAKAWA H., AWAMOTO K., Wakitani M., SHINODA T. and Akira Takahashi : Determination of Optimum Wavelength of Far-UVC for Virucidal and Bactericidal Effects Using Plasma Emission-Based Light Modules, ASM Microbe 2023, Houston, Jun. 2023.
13.
Hitoshi Takagi, Antonio Norio Nakagaito, Nozomi Kawakami, Akira Takahashi and Takeshi Nikawa : Isolation of cellulose nanofibers from soybean waste, The 9th International Forum on Advanced Technologies and The 4th Japan-Taiwan International Engineering Forum (IFAT & JTIEF 2023), 50033_1-50033_2, Taipei, Mar. 2023.
14.
Shiho Fukushima, Takaaki Shimohata, Junko Kido, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Campylobacter jejuni induce autophagy for the bacterial invasion in the host epithelial cells, 54th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Dec. 2019.
15.
Toshitaka Ikehara, Mutsumi Nakahashi, Takahiro Emoto, Masatake Akutagawa, Koichiro Tsuchiya, Akira Takahashi and Yohsuke Kinouchi : Effects of reactive oxygen species induced by 405 nm light irradiation on Hela S3 cells, The Joint Annual Meeting of the Bioelectromagnetics Society and the European BioElectromagnetics Association, Montpellier, Jun. 2019.
16.
Aya Tentaku, Takaaki Shimohata, Sho Hatayama, Junko Kido, Anh Quoc Nguyen, Yuna Kanda, Shiho Fukushima, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Role of host cellular unfolded protein response signaling during Campylobacter jejuni infection, 53th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Mar. 2019.
17.
Anh Quoc Nguyen, Takaaki Shimohata, Sho Hatayama, Aya Tentaku, Junko Kido, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Metabolic changing in epithelial cell during Vibrio parahaemolyticus infection, 53th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Mar. 2019.
18.
Yukiko Tomioka, Hidehiro Umehara, Shinya Watanabe, Masahito Nakataki, Masuda Rumiko, Kazuaki Mawatari, Takeshi Nikawa, Akira Takahashi, Shusuke Numata and Tetsuro Ohmori : Altered plasma metabolites related to one-carbon metabolism in schizophrenia., WFSBP Asia Pacific Regional Congress of Biological Psychiatry, Kobe, Sep. 2018.
19.
Toshiya Okahisa, Masahiro Sogabe, Mayu Uyama, Tadahiko Nakagawa, Tetsu Tomonari, Tatsuya Taniguchi, Koichi Okamoto, Tetsuji Takayama, Takaaki Shimohata, Takashi Uebanso, Kazuaki Mawatari, Akira Takahashi, Takahiro Emoto, Masatake Akutagawa, M Yamada and M Fukuhara : Development Of A Multi-Ring Type Roller Pump Unit Equipped To A Compact And Convenient Ascites Purification Machine For Cell-Free And Concentrated Ascites Reinfusion Therapy (CART)., ASAIO 64th Annual Conference, Washington, D.C., Jun. 2018.
20.
Aya Tentaku, Takaaki Shimohata, Sho Hatayama, Anh Quoc Nguyen, Junko Kido, Shiho Fukushima, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Induction of the unfolded protein response (UPR) decreased Campylobacter jejunin invasion, 118th General Meeting of the American Society for Microbiology, Jun. 2018.
21.
Shiho Fukushima, Yuri Sato, Takaaki Shimohata, Junko Kido, Yuna Kanda, Aya Tentaku, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Campylobacter jejuni Utilized Autophagy for the Bacterial Survival in the Host Epithelial Cells, 118th General Meeting of the American Society for Microbiology, Jun. 2018.
22.
Junko Kido, Takaaki Shimohata, sachie amano, sho hatayama, yuri sato, yuna kanda, aya tentaku, shiho Fukushima, Mutsumi Nakahashi, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : CFTR reduced microtubule-mediated Campylobacter jejuni invasion, 52th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Feb. 2018.
23.
Syo Hatayama, Takaaki Shimohata, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : The relation of cellular Tight Junctions formation and Campylobacter jejuni invasion in intestinal epithelial cells, 51th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Feb. 2017.
24.
Asami Iwanaka, Mamiko Soga, Eiichi Kotake-Nara, Akihito Nagao, Rie Mukai, Akira Takahashi and Junji Terao : Effect of Fucoxanthin and Neoxanthin on Blue Light-Emitting Diode-Irradiated Photosensitized Oxidation in Liposomal Membranes andMouse Fibroblast Cells, The 6th International Conference on Food Factors: Bioconvergence for Food Function, Soul, Republic of Korea, Nov. 2015.
25.
Tadahiko Nakagawa, Yoshifumi Takaoka, Hironori Tanaka, Kumiko Tanaka, Tetsuji Takayama, Takaaki Shimohata, Takashi Uebanso, Kazuaki Mawatari, Akira Takahashi, Masatake Akutagawa, Takahiro Emoto, Yohsuke Kinouchi, Toru Murashima, Satoru Yamaji, Zenji Tanaka, Masahiro Sogabe and Toshiya Okahisa : Roller Pump Circulation System For Preventing Filter Clogging During Cell-free and Concentrated Ascites Reinfusion Therapy (cart)., The 61th Annual Conference of American Society for Artificial Internal Organs(ASAIO), Chicago, Jun. 2015.
26.
Tsunedomi Akari, Masamura Akinori, Mutsumi Nakahashi, Nishisaka Risa, Kazuaki Mawatari, Takaaki Shimohata, Takashi Uebanso, Katsuyuki Miyawaki, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Disinfection system with UVA-LED for hydroponic nutrient solution, 6th FEMS Microbiology Congress, Jun. 2015.
27.
Hatayama Sho, Takaaki Shimohata, Negoro Sachie, Sato Yuri, Kido Junko, Mutsumi Nakahashi, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : The denudation of lateral part promote Campylobacter jejuni invasion in Caco-2 cells., 6th FEMS Microbiology Congress, Jun. 2015.
28.
Takashi Uebanso, Takaaki Shimohata, Iba Hitomi, Nishimura Kazuya, Taniguchi Yuichi, Kazuki Horikawa, Mutsumi Nakahashi, Kazuaki Mawatari and Akira Takahashi : COMBINATION BETWEEN A FEW T3SS INJECTISOME AND A LOT EFFECTOR FOR KILLING HOST CELLS ON VIBRIO PARAHAEMOLYTICUS, 6th FEMS Microbiology Congress, Jun. 2015.
29.
Takaaki Shimohata, Negoro Sachie, Kido Junko, Hatayama Sho, Sato Yuri, Iba Hitomi, Mutsumi Nakahashi, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : INFECTION OF CAMPYLOBACTER JEJUNI REDUCES CFTR MEDIATED CL- SECRETION IN T-84, 6th FEMS Microbiology Congress, Jun. 2015.
30.
Ayumi Yoshimoto, Takashi Uebanso, Kazuaki Mawatari, Mutsumi Nakahashi, Takaaki Shimohata and Akira Takahashi : Low dose antibiotics treatment in the prenatal period affect newborns health in later life, 12th Asian Congress of Nutrition, 70, May 2015.
31.
Takashi Uebanso, Ai Ohnishi, Takaaki Shimohata, Mutsumi Nakahashi, Kazuaki Mawatari and Akira Takahashi : Acceptable daily intake levels of sucralose consumption reduces fecal Clostridium cluster 4 in mouse, 12th Asian Congress of Nutrition, 70, May 2015.
32.
Takaaki Shimohata, Sachie Negoro, Sho Hatayama, Yuri Sato, Hitomi Iba, Mutsumi Aihara, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Campylobacter jejuni Infection Reduces Cftr Mediated Cl- Secretion In T-84, American Society for Microbiology 114th General Meeting, May 2014.
33.
Mutsumi Aihara, Takashi Uebanso, Takaaki Shimohata, Kazuaki Mawatari, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : Simultaneous irradiation with different wavelengths of ultraviolet light has synergistic bactericidal effect on Vibrio parahaemolyticus, 48th US-Japan Cooperative Medical Sciences Program Conference on cholera and Other Bacterial Enteric Infections, Feb. 2014.
34.
Sachie Negoro, Takaaki Shimohata, Syo Hatayama, Mari Matsumoto, Yuri Sato, Mutsumi Aihara, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Suppression of CFTR-mediated Cl- transport in Campylobacter jejuni infection, International Symposium Hannover - Tokushima Research Communication, Aug. 2013.
35.
Takashi Uebanso, Hitomi Iba, Shoko Asada, Takaaki Shimohata, Mutsumi Aihara, Kazuaki Mawatari and Akira Takahashi : Regulation and effects of VP1671 (VscQ) on virulence of Vibrio parahaemolyticus, 5th FEMS Microbiology Congress, Jul. 2013.
36.
Mutsumi Aihara, Takaaki Shimohata, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Synergistic bactericidal effect of ultraviolet light with a combination of different wavelength, 5th FEMS Microbiology Congress, Jul. 2013.
37.
Kazuaki Mawatari, Tam Thanh Thi Le, Miki Maetani, Tomomi Yamamoto, Airi Honjo, Mutsumi Aihara, Takaaki Shimohata, Takashi Uebanso and Akira Takahashi : VP2118 has major roles in Vibrio parahaemolyticus response to oxidative stress, 5th FEMS Microbiology Congress, Jul. 2013.
38.
Teppei Hoshiyama, Masatake Akutagawa, Mutsumi Aihara, Mario Hayashida, Akira Takahashi, Takahiro Emoto, Shinsuke Konaka and Yohsuke Kinouchi : Gene expression analysis of Vibrio parahaemolyticus for UV irradiation, BioEM2013, 94, Thessaloniki, Jun. 2013.
Kazuaki Mawatari, Tam Thanh Thi Le, Miki Maetani, Tomomi Yamamoto, Mutsumi Aihara, Takaaki Shimohata, Takashi Uebanso and Akira Takahashi : VP2118 has major roles in Vibrio parahaemolyticus response to oxidative stress, US-Japan Cooperative Medical Science Program, 47th Annual Joint Panel Meeting on Cholera and Other Bacterial Enteric Infections, Dec. 2012.
40.
Takashi Uebanso, Hitomi Iba, Shoko Asada, Takaaki Shimohata and Akira Takahashi : REGULATION AND EFFECTS OF VP1671(VSCQ) ON VIRULENCE Of VIBRIO PARAHAEMOLYTICUS, International Symposium on Single cell Analysis, Kyoto, Nov. 2012.
41.
Masachika Ishizaki, Yusuke Manabe, Mutsumi Aihara, Akira Takahashi, Masatake Akutagawa, Takahiro Emoto, Yohsuke Kinouchi and Toshitaka Ikehara : Improvement of a pipe type UVA-LED sterilizer using a condenser lens, 34th Annual Conference of the bioelectromagnetics society (34 BEMS) (Abstract), 189-190, Brisbane, Jun. 2012.
Toshitaka Ikehara, Mutsumi Aihara, Zehong Su, Akira Takahashi, Masatake Akutagawa and Yohsuke Kinouchi : Effects of UVA radiation on growth of RAW 264.7 cells, 34th Annual Conference of the bioelectromagnetics society (34 BEMS) (Abstract), 179-180, Brisbane, Jun. 2012.
(要約)
マウス由来のRAW 264.7細胞に対してUVAを照射した際の増殖の違いについて検討した．
43.
Kazuaki Mawatari, Yuka Isumi, Minami Hirayama, Miki Maetani, Tomomi Yamamoto, Sayaka Hayashida, Hitomi Iba, Mutsumi Aihara, Takaaki Shimohata and Akira Takahashi : OtnA-OtnB modulate capsular polysaccharide and polymyxin B resistance in Vibrio parahaemolyticus, 112th General Meeting of the American Society for Microbiology, Jun. 2012.
44.
Mutsumi Aihara, Kazuaki Mawatari, Takaaki Shimohata and Akira Takahashi : Bactericidal Effect of Ultraviolet Light with a Combination of Different Wavelengths, 112th General Meeting of the American Society for Microbiology, Jun. 2012.
45.
Hitomi Iba, Takaaki Shimohata, Masayuki Yamato, Kazuaki Mawatari and Akira Takahashi : The effect of VP1671 (vscQ) on virulence of Vibrio parahaemolyticus, 4th FEMS Microbiology Congress, Jun. 2011.
46.
Kazuaki Mawatari, Yumi Yoneda, Manami Honda, Hitomi Iba, Mutsumi Aihara, Zehong Su, Takaaki Shimohata, Masayuki Yamato and Akira Takahashi : VPA1604, a protein containing phosphorylated tyrosine, modulates high molecular weight capsular polysaccharide in Vibrio parahaemolyticus, 4th FEMS Microbiology Congress, Jun. 2011.
47.
Yuya Manabe, Ryosuke Nakagawa, Su Zhehong, Miki Maetani, Kenji Teranishi, Naoyuki Shimomura and Akira Takahashi : Influences of Pulsed Electric Fields on the Gene Expression of Pathogenic Bacteria, Proceedings of the 18th IEEE International Pulsed Power Conference, 1242-1246, Chicago, Jun. 2011.
Kazuaki Mawatari, Yumi Yoneda, Manami Honda, Hitomi Iba, Mutsumi Aihara, Zehong Su, Takaaki Shimohata, Masayuki Yamato and Akira Takahashi : VPA1604, a protein tyrosine kinase, modulates high molecular weight capsular polysaccharide in Vibrio parahaemolyticus, US-Japan Cooperative Medical Science Program, 45th Annual Joint Panel Meeting on Cholera and Other Bacterial Enteric Infections Panel, Kyoto, Dec. 2010.
49.
Miku Maeda, Yohsuke Kinouchi, Akira Takahashi, Takahiro Emoto, Masatake Akutagawa and Xin Lian : Novel sterilization device using 265nm UV-LED for escherichia coli, Proceedings of The Bioelectromagnetics Society 32nd Annual Meeting, 43, Seoul, Jun. 2010.
50.
Yuhsuke Manabe, Takahiro Emoto, Masatake Akutagawa, Akira Takahashi and Yohsuke Kinouchi : Simulation of UVA-LED irradiance distribution, Proceedings of The Bioelectromagnetics Society 32nd Annual Meeting, 43, Seoul, Jun. 2010.
51.
Tsuyosi Okahisa, Masayuki Yamato, Akira Takahashi, Masatake Akutagawa, Takahiro Emoto and Yohsuke Kinouchi : UVA-LED for sterilizing water in a water tank, Proceedings of The Bioelectromagnetics Society 32nd Annual Meeting, 42, Seoul, Jun. 2010.
52.
Tomohiro Oshita, Keiko Shintani, Mai Katayama, Takahiro Emoto, Masatake Akutagawa, Akira Takahashi and Yohsuke Kinouchi : An investigation of the sterilization effect of 385nm UVA-LED, Proceedings of The Bioelectromagnetics Society 32nd Annual Meeting, 43, Seoul, Jun. 2010.
53.
Takaaki Shimohata, Masayuki Nakano, Lian Xin, Kazuaki Mawatari, Masayuki Yamato and Akira Takahashi : Vibrio parahaemolyticus modulate IL-8 secretion through dual pathway, 110th General Meeting of the American Society for Microbiology, San Diego, CA, U.S.A., Jun. 2010.
54.
Ryosuke Nakagawa, Kazuki Siroyama, Su Zehong, Kenji Teranishi, Naoyuki Shimomura and Akira Takahashi : Effects of Pulse electric Fields to the Pathogenic Bacteria, Proceedings of the 2010 IEEE Power Modulators and High-Voltage Conference, 686-689, Atlanta, May 2010.
(要約)
The pulsed power technology is gaining ground on applications to biological field such as sterilization with pulse electric fields or discharges and induction of the apoptosis with pulse electric fields. Under the circumstances, the pulse electric fields clearly have some influence on organism. To figure out the influence and mechanism, we conducted an experiment. The pulse electric fields were applied to the pathogenic bacteria, and manifestation of RNAs which affected pathogenicity was examined. A system was developed to apply the pulsed electric fields to bacteria. The pulsed power generator, which consists of a Blumlein-type pulse forming network (B-PFN), outputs pulses with width of 100 ns in the case of 5 L-C stages. The electrodes chamber was filled with the solution (2 ml) with bacteria. The separation of the electrodes was 5 mm and approximately uniform electric field was applied to the solution. The manifestation of RNAs was analyzed with the method of polymerase chain reaction, PCR Vibrio parahaemolyticus (RIMD 2210633) was selected to examine. The manifestations of RNAs as VP1699, VP1680, VPA1321, VPA1327, VPA1346, TDH, and RNA16S were examined with the PCR method. Although RNA16S does not become an index for pathogenicity, evaluation of RNA16S implies a survival ratio of the bacteria. The initial density of bacteria solution was regulated to be 109 /ml. The peak voltage was approximately 6, 12 kV and the number of applied pulses was 1000 for each sample. The tendency of increase in manifestation was found by the application of pulse electric fields for VP1699 and VP1680 with relation of TTSS(1).
Yagi Noriyuki, Mirei Mori, Hamamoto Akiko, Lian Xin, Nakano Masayuki, Masatake Akutagawa, Tachibana Satoko, Akira Takahashi, Toshitaka Ikehara and Yohsuke Kinouchi : EFFECTS OF 365NM UVA-LED ON BACTERIA, The Bioelectromagnetics Society 30th Annual Meeting, 350-351, San Diego, Jun. 2008.
56.
Akira Takahashi, M. Nakano, Kazuaki Mawatari, Nagakatsu Harada and Yutaka Nakaya : Vibrio cholerae El tor Hemolysin Activates Cyclic AMT Dependent Cl-Secretory Pathways which Xaused Diarrhea, 108th General Meeting of the American Society for Microbiology, Boston, Jun. 2008.
57.
Hamamoto Akiko, Akira Takahashi, Nakano Masayuki, Lian Xin, Tachibana Satoko, Yagi Noriyuki, Tetutani Kayo, Masayuki Yamato, Masatake Akutagawa, Toshitaka Ikehara, Yutaka Nakaya and Yohsuke Kinouchi : Availability of UVA-light emitting diodes for disinfection system, 第22回生体・生理工学シンポジウム, Harbin, Jan. 2008.
58.
Lian Xin, Akira Takahashi, Maeda Miku, Yagi Noriyuki, Tachibana Satoko, Masayuki Yamato, Hamamoto Akiko, Masatake Akutagawa, Nakano Masayuki, Yutaka Nakaya and Yohsuke Kinouchi : New surface sterilization system using UV-LED for vegetables, Proceedings of the International Symposium on Biological and Physiological Engineering /The 22nd SICE Symposium on Biological and Physiological Engineering, 257-259, Harbin, Jan. 2008.
(キーワード)
UV-LED / surface / sterilization / 365nm
59.
Hamamoto Akiko, Akira Takahashi, Nakano Masayuki, Lian Xin, Tachibana Satoko, Yagi Noriyuki, Tetutani Kayo, Tetsuro Koga, Masayuki Yamato, Masatake Akutagawa, Toshitaka Ikehara and Yohsuke Kinouchi : Availability of UVA-light emitting diodes for disinfection system, Proceedings of the International Symposium on Biological and Physiological Engineering /The 22nd SICE Symposium on Biological and Physiological Engineering, 109-112, Harbin, Jan. 2008.
60.
Yagi Noriyuki, Mirei Mori, Hamamoto Akiko, Nakano Masayuki, Masatake Akutagawa, Tachibana Satoko, Akira Takahashi, Toshitaka Ikehara and Yohsuke Kinouchi : Development of a tank-type sterilization device using 365 nm UVA-LED, Proceedings of the International Symposium on Biological and Physiological Engineering /The 22nd SICE Symposium on Biological and Physiological Engineering, 113-116, Harbin, Jan. 2008.
61.
Lian Xin, Akira Takahashi, Nakano Masayuki and Yutaka Nakaya : Vibrio parahaemolyticus elevates interferon alpha production in intestinal-like epithelial cells CACO-2 cells, VIBRIO 2007(The second conference on the Biology of Vibrios), Paris, Nov. 2007.
62.
Nakano Masayuki, Akira Takahashi and Yutaka Nakaya : Adrenergic regulation of Vibrio parahaemolyticus pathogenicity by the modulation of viburence-associated gene expressions, VIBRIO 2007(The second conference on the Biology of Vibrios), Paris, Nov. 2007.
63.
Noriyuki Yagi, Mirei Mori, Akiko Hamamoto, Masatake Akutagawa, Satoko Tachibana, Akira Takahashi, Toshitaka Ikehara, Yohsuke Kinouchi and Masayuki Nakano : Sterilization Using 365 nm UV-LED., 29th IEEE EMBS Annual International Conference, 5841-5844, Lyon, France, Aug. 2007.
Hamamoto Akiko, Mori Mirei, Nakano Masayuki, Wakikawa Noriko, Toshitaka Ikehara, Yohsuke Kinouchi, Masatake Akutagawa, Akira Takahashi and Yutaka Nakaya : Water disinfection system using UVA-light emitting diodes and its effects on bacterial DNA., 107th ASM general meeting, Toronto,Canada, May 2007.
65.
Akira Takahashi, Nakano Masayuki, Miyoshi Shinichi, Hamamoto Akiko and Yutaka Nakaya : Pore formation of Vibrio mimicus hemolysin in lipid bilayers., 107th ASM general meeting, Toronto, Canada, May 2007.
66.
Akira Takahashi, Hamamoto Akiko, Wakikawa Noriko, Mori Mirei, Nakano Masayuki, Masatake Akutagawa, Yohsuke Kinouchi and Yutaka Nakaya : New water sterilization system used by UVA-LED., The 41st Joint Conference US-Japan Cooperative Medical Science Program Cholera Panel, Gifu, Japan, Nov. 2006.
67.
Nakano Masayuki, Akira Takahashi and Yutaka Nakaya : Norepinephrine modulates the pathogencity of Vibrio parahaemolyticus., The 41st Joint Conference US-Japan Cooperative Medical Science Program Cholera Panel, Gifu, Japan, Nov. 2006.
68.
Morishima Masaki, Akira Takahashi and Yutaka Nakaya : Transthyretin and serotonin levels in the hippocampus are decreased in SPORTS rats., 36th Society for Neuroscience, Atlanta, USA, Oct. 2006.
69.
Mirei Mori, Akiko Hamamoto, Masayuki Nakano, Masatake Akutagawa, Akira Takahashi, Toshitaka Ikehara and Yohsuke Kinouchi : Effect of ultraviolet LED on bacteria, Proceedings of 2006 World Congress on Medical Physics and Biomedical Engineering, Seoul, Korea, August 27-September 1, 2006, Vol.1, 1218-1221, Seoul, Aug. 2006.
70.
Mirei Mori, Hamamoto Akiko, Nakano Masayuki, Masatake Akutagawa, Akira Takahashi, Toshitaka Ikehara and Yohsuke Kinouchi : Effects of ultraviolet LED on bacteria., World Congress on Medical Physics and Biomedical Engineering 2006, Korea, Aug. 2006.
71.
Morishima Masaki, Nagakatsu Harada, Hara Sayuri, Akira Takahashi and Yutaka Nakaya : Hippocampal norepinephrine (NE) level and exercise behavior in SPORTS rats., 15th Annual Meeting of the International Behavioral Neuroscience Society, Briitish Columbia, Canada, May 2006.
72.
Akiko Hamamoto, Masayuki Nakano, Toshitaka Ikehara, Masatake Akutagawa, Yohsuke Kinouchi, Yutaka Nakaya and Akira Takahashi : A new water sterilization system which use UVA-light emitting diode (Q-401)., 106th ASM general meeting, Florida, USA, May 2006.
73.
Nakano Masayuki, Akira Takahashi, Sakai Yuko and Yutaka Nakaya : Response of Vibrio parahaemolytiocus to neuroendcrine hormone norepinephrine (D-026)., 106th ASM general meeting, Florida,USA, May 2006.
74.
Nakano Masayuki, Akira Takahashi, Sakai Yuko and Yutaka Nakaya : Norepinephrine modulates the pathogenicity of Vibrio parahameolyticus., 11th Asian conference on diarrhoeal diseases and nutrition, Bangkok, Mar. 2006.
75.
Nakano Masayuki, Akira Takahashi, Sakai Yuko and Yutaka Nakaya : Response of enteropathogen to neuroendocrine hormone ., COE international conference on biological mechanism for stress control, Tokushima, Japan, Aug. 2005.
76.
Akira Takahashi, Nakano Masayuki, Miyoshi Shinichi, Nagakatsu Harada and Yutaka Nakaya : (B-053) Hemolysin produced by Vibrio mimicus activates two Cl- secretory pathways in cultured intestinal-like cells., 105th American society for microbiology general meeting, Atlanta, Georgia, USA, Jun. 2005.
Duc Quang Tran, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Unraveling the Capacity and Mechanism of Gut Microbiota in Enhancing Essential Amino Acid Provision to Juvenile Mice Under Essential Amino Acid-Deficient Diet, 第268回 徳島医学会学術集会(令和5年度冬季), Mar. 2024.
Duc Quang Tran, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Unraveling the Capacity and Mechanism of Gut Microbiota in Enhancing Essential Amino Acid Provision to Juvenile Mice Under Essential Amino Acid-Deficient Diet, 2023 Tokushima Bioscience Retreat, Sep. 2023.
Bui Kim Thi Ngan, Kazuaki Mawatari, SHINODA Koichi, 平川 仁, 粟本 健司, 脇谷 正幸, 篠田 傳 and Akira Takahashi : Determination of optimum wavelength of far-UVC for virucidal and bactericidal effects using plasma emission-based light modules, 日本防菌防黴学会 第50回年次大会, Aug. 2023.
Bui Kim Thi Ngan, Kazuaki Mawatari, Takahiro Emoto, Shiho Fukushima, Takashi Uebanso, Takaaki Shimohata, Masatake Akutagawa, Yohsuke Kinouchi and Akira Takahashi : UV-LED irradiation reduces the infectivity of herpes simplex virus type 1 by targeting different viral components depending on the peak, 第265回徳島医学会学術集会, Jul. 2022.
Toshitaka Ikehara, Mutsumi Aihara, Koichiro Tsuchiya, Takahiro Emoto, Masatake Akutagawa, Akira Takahashi and Yohsuke Kinouchi : Studies of reactive oxygen species scavenging system of cultured cells by using LED light irradiation, LED総合フォーラム2022 in 徳島, 193-198, Jan. 2022.
Anh Quoc Nguyen, Takaaki Shimohata, Anh Quoc Nguyen, Sho Hatayama, Aya Tentaku, Junko Kido, Takashi Uebanso, Kazuaki Mawatari and Akira Takahashi : Metabolic changing in epithelial cell during Vibrio parahaemolyticus infection, 日米医学協力研究会コレラ・細菌性腸管感染症専門部会, Aug. 2018.
馬渡 一諭, 安井 実希, 本庄 アイリ, 西坂 理沙, 枝川 美幸, 岩本 夏美, 渡邊 瞳, 下畑 隆明, 上番増 喬, 髙橋 章 : Screening of genes related with ultraviolet A-sensitivity by transposon mutagenesis in Vibrio parahaemolyticus, 90th Annual Meeting of Japanese Society of bacteriology, 46, 2017年3月.
Mutsumi Aihara, Takashi Uebanso, Takaaki Shimohata, Kazuaki Mawatari and Akira Takahashi : Synergistic bactercidal effect of Ultraviolet light with a combination of different, 日米医学協力研究会コレラ・細菌性腸管感染症専門部会日本側総会, Aug. 2013.
Tam Thanh Thi Le, Kazuaki Mawatari, Mutsumi Aihara, Takaaki Shimohata, Takashi Uebanso and Akira Takahashi : VP2118 has major roles in Vibrio parahaemolyticus response to oxidative stress, 日米医学協力研究会コレラ・細菌性腸管感染症専門部会日本側総会, Aug. 2012.