Parathyroid hormone-dependent endocytosis of renal type IIc Na-Pi cotransporter.

Hereditary hypophosphatemic rickets with hypercalciuria results from mutations of the renal type IIc Na-P(i) cotransporter gene, suggesting that the type IIc transporter plays a prominent role in renal phosphate handling. The goal of the present study was to investigate the regulation of the type IIc Na-P(i) cotransporter by parathyroid hormone (PTH). Type IIc Na-P(i) cotransporter levels were markedly increased in thyroparathyroidectomized (TPTX) rats. Four hours after administration of PTH, type IIc transporter protein levels were markedly decreased in the apical membrane fraction but recovered to baseline levels at 24 h. Immunohistochemical analyses demonstrated the presence of the type IIc transporter in the apical membrane and subapical compartments in the proximal tubular cells in TPTX animals. After administration of PTH, the intensity of immunoreactive signals in apical and subapical type IIc transporter decreased in the renal proximal tubular cells in TPTX rats. Colchicine completely blocked the internalization of the type IIc transporter. In addition, leupeptin prevented the PTH-mediated degradation of the type IIa transporter in lysosomes but had no effect on PTH-mediated degradation of the lysosomal type IIc transporter. In PTH-treated TPTX rats, the internalization of the type IIc transporter occurred after administration of PTH(1-34) (PKA and PKC activator) or PTH(3-34) (PKC activator). Thus the present study demonstrated that PTH is a major hormonal regulator of the type IIc Na-P(i) cotransporter in renal proximal tubules.

American Journal of Physiology, Renal Physiology


Effects of a palatinose-based liquid diet (Inslow) on glycemic control and the second-meal effect in healthy men.

Postprandial hyperglycemia induces prolonged hyperinsulinemia, which is a risk factor for type 2 diabetes mellitus. Foods with a low glycemic index blunt the rapid rise in postprandial plasma glucose and insulin levels. We herein investigated the effects of a novel, palatinose-based liquid diet (Inslow, Meiji Dairy Products, Tokyo, Japan) on postprandial plasma glucose and insulin levels and on the rate of substrate oxidation in 7 healthy men. Furthermore, to examine the effects of Inslow on the second-meal effect, we quantified our subjects' postprandial plasma glucose, insulin, and free fatty acid levels for up to 7 hours after they ingested a breakfast containing Inslow or control formula, followed by a standard lunch 5 hours later. Our results showed that peak plasma glucose and insulin levels 30 minutes after Inslow loading were lower than after control formula loading. Postprandial fat oxidation rates in the Inslow group were higher than in the control formula group (P < .05). In the second-meal effect study, plasma glucose and insulin levels after lunch in the Inslow group were lower than in the control formula group (P < .01), although the peak levels in these groups were not different. The free fatty acid concentration in the Inslow group immediately before lunch was significantly lower than in the control formula group (P < .05). In conclusion, consumption of Inslow at breakfast appears to improve patient glycemic control by reducing their postprandial plasma glucose and insulin levels after lunch (second-meal effect).


Water extract of Cordyceps sinensis (WECS) inhibits the RANKL-induced osteoclast differentiation.

It has been reported that Cordyceps sinensis, a traditional Chinese medicine, has various pharmacological effects. The aim of this study was to clarify the effect of water extract of Cordyceps sinensis (WECS) on osteoclast differentiation in vitro. In mouse bone marrow cells and monocyte/macrophage cell line RAW264.7, WECS dose-dependently inhibited the receptor activator of nuclear factor kappa B (NF-kappaB) ligand (RANKL)-induced osteoclast differentiation by tartrate-resistant acid phosphatase (TRAP) staining. In fact, cytotoxic effect was not observed in the RAW264.7 cells treated with WECS. Moreover, the mRNA expression of osteoclast related genes (calcitonin receptor, cathepsin K, matrix metalloprotease 9 and nuclear factor of activated T cells c1) was also inhibited by WECS. Investigation of inhibitory mechanism by using electrophoretic mobility shift assay (EMSA) and Western blot analysis revealed that WECS inhibited the activation of NF-kappaB through the prevention of IkappaBalpha phosphorylation. In conclusion, the present results demonstrate for the first time that WECS is a potent inhibitor of the RANKL-induced osteoclast differentiation through a mechanism involving the NF-kappaB pathway.


Acute effect of oral phosphate loading on serum fibroblast growth factor 23 levels in healthy men.

Serum fibroblast growth factor 23 (FGF23) is a novel phosphaturic factor and important for the regulation of inorganic phosphate (Pi) homeostasis. In this study, we examined an acute effect of oral Pi loading on serum FGF23 levels to clarify the role in rapid adjustment of serum Pi level. We performed a randomized, double-blind, crossover study in eight healthy male volunteers. The subjects were alternately served one of three test meals containing different Pi amounts (400 mg (P400), 800 mg (P800), and 1200 mg (P1200)) as lunch at noon. The postprandial changes in serum levels of Pi, Ca, 1,25-dihydroxyvitamin D, intact-parathyroid hormone (iPTH), intact-FGF23 (iFGF23), and urinary excretion of Pi and Ca until 8 h after Pi loading were estimated. Serum Pi levels and urinary Pi excretion significantly increased within 1 h after P400 and P800 intake. Serum iPTH levels at 1-2 and 4-6 h after P1200 intake was significantly higher than those of P400 intake. Serum iFGF23 levels slightly decreased up to 8 h after P400 intake and up to 6 h after P800 intake, but not changed in P1200 intake. Significant increase of iFGF23 was observed at 8 h after P1200 intake compared with both P400 and P800 intake. Additionally, negative association was detected between iFGF23 and serum Pi, whereas positive association was observed between iPTH and serum Pi during the short period. We conclude that oral Pi loading cannot rapidly increase serum FGF23 level. FGF23 may be not associated with rapid adaptation of Pi homeostasis.


リンとビタミンDの相互作用

リンとビタミンDの相互作用


Restraint stress alters the duodenal expression of genes important for lipid metabolism in rat.

Stress, such as trauma and injury, is known to cause transcriptional changes in various tissues; however, there is little information on tissue-specific gene expression in response to stress. Here, we have examined duodenal gene expression in rats subjected to whole-body immobilization in order to elucidate the mechanism underlying the stress response in the duodenum--one of the tissues that is most sensitive to external stress. DNA microarray analysis revealed that the immobilization for 2 weeks caused great changes in gene expression in the rat duodenum: 165 genes exhibited more than a two-fold change in expression level (103 up-regulated; 62 down-regulated). In addition, functional classification of these genes showed that immobilization preferentially stimulated the expression of genes related to lipid metabolism, including genes encoding mitochondrial HMG-CoA synthase, a key enzyme in ketogenesis; solute carrier 27A2, a fatty acid transporter; and dienoyl CoA reductase, a key enzyme in beta-oxidation. To elucidate the factors mediating these immobilization-induced changes, we treated rats and small intestinal IEC-6 cells with dexamethasone and hydrogen peroxide. In both rats and IEC-6 cells, treatment with dexamethasone induced changes in gene expression that mimicked the immobilization-mediated increase in expression of the mitochondrial HMG-CoA synthase and dienoyl CoA reductase transcripts, suggesting that stress-induced synthesis of glucocorticoid hormones mediates, at least in part, the stress response in the duodenum. These results suggest that immobilization may alter lipid metabolism in the small intestine by modifying the expression of specific genes through which the small intestine may seek to protect itself from stress-induced damage.


Effect of late evening snack with rice ball on energy metabolism in liver cirrhosis.

This study investigates the effects of a late evening snack (LES), of 200 kcal of rice ball, on energy metabolism in cirrhotic patients. Impaired nutritional metabolism has been associated with cirrhosis, and frequent intake of small meals may prevent early-onset starvation, and maintain nourishment in these patients. Twenty-one cirrhotic patients and 26 control subjects (Control) were recruited for this study. Patients were subsequently treated by LES (LC-LES) and by a non-LES regimen (LC-NLES). Resting energy expenditure and respiratory quotient (RQ) were assessed by indirect calorimetry at 0830, 1130 and 1430. Blood glucose and non-esterified fatty acids (NEFA) were measured just before the energy metabolism measurements. The regular diet included three major meals and LES, at 0900, 1200, 1800 and 2100, respectively. The Control and LC-NLES groups received only the major meals, whereas the LC-LES group received three meals plus 200 kcal LES for 7 days. There was no difference in the total energy intake among Control, LC-NLES and LC-LES groups. Respiratory quotient in LC-NLES was significantly lower than that of Control at 0830. Respiratory quotient value in LC-LES significantly elevated from that in LC-NLES. The RQ values did not differ among Control, LC-NLES and LC-LES at 2 h after the meal (1130 and 1430). Non-esterified fatty acids in LC-LES were lower than that in LC-NLES after overnight fasting. The ingestion of a 200 kcal rice ball LES can improve the nutritional metabolism in cirrhotic patients.


Immobilization decreases duodenal calcium absorption through a 1,25-dihydroxyvitamin D-dependent pathway.

Immobilization induces significant and progressive bone loss, with an increase in urinary excretion and a decrease in intestinal absorption of calcium. These actions lead to negative calcium balance and the development of disuse osteoporosis. The aims of this study were to evaluate the molecular mechanisms of decreased intestinal calcium absorption and to determine the effect of dietary 1,25-dihydroxyvitamin D [1,25(OH)2D] and a high-calcium diet on bone loss due to immobilization. The immobilized rat model was developed in the Bollman cage III to induce systemic disuse osteoporosis in the animals. There was a significant decrease in lumbar bone mineral density (BMD) and intestinal calcium absorption in the immobilized group compared with the controls. Serum 25-hydroxyvitamin D concentration did not change, but 1,25(OH)2D concentration decreased significantly. The mRNA levels of renal 25-hydoxyvitamin D 24-hydroxylase (24OHase) increased, whereas those of renal 25-hydroxyvitamin D 1-alpha hydroxylase (1alpha-hydroxylase), duodenal transient receptor potential cation channel, subfamily V, member 6 (TRPV6), TRPV5, and calbindin-D9k were all decreased. A high-calcium diet did not prevent the reduction in lumbar BMD or affect the mRNA expression of proteins related to calcium transport. Dietary administration of 1,25(OH)2D increased the intestinal calcium absorption that had been downregulated by immobilization. TRPV6, TRPV5, and calbindin-D9k mRNA levels were also upregulated, resulting in prevention of the reduction in lumbar BMD. Therefore, it is concluded that dietary 1,25(OH)2D prevented decreases in intestinal calcium absorption and simultaneously prevented bone loss in immobilized rats. However, it remains unclear that calcium absorption and expression of calcium transport proteins are essential for the regulation of lumbar BMD.


A novel function of phosphate-mediated intracellular signal transduction pathways


病態栄養専門師のための病態栄養ガイドブック

病態栄養専門師のための病態栄養ガイドブック


ナトリウム依存症リントランスポータ-の調節機構

ナトリウム依存症リントランスポータ-の調節機構


Alternative promoters and renal cell-specific regulation of the mouse type IIa sodium-dependent phosphate cotransporter gene

The type IIa sodium-dependent phosphate cotransporter (NPT2a) expressed in renal proximal tubules represents an important determinant in maintaining inorganic phosphate (Pi) homeostasis. In the present study, we identified two variant transcripts of the mouse NPT2a gene, Npt2a-v1 and Npt2a-v2, characterized by the presence of alternative first exons (either exon 1A or exon 1B). The chromosomal structure analysis revealed that the Npt2a gene comprises of two promoters (promoters 1 and 2) and 14 exons, and spans approximately 17 kb. Quantitative PCR analysis showed that renal mRNA levels of both the variants markedly decreased in X-linked vitamin D-resistant hypophosphatemic rickets (Hyp) mice compared to normal littermates. Interestingly, transcriptional activity of a reporter gene, containing Npt2a promoters 1 and 2, was renal cell-specifically increased by 1alpha, 25(OH)2D3 and its analogs. The deletion analysis revealed that the CAAT box in the Npt2a promoter 2 is important for the 1alpha, 25(OH)2D3-dependent renal cell-specific activation of the reporter gene. These data suggested that two alternative promoters control the renal expression of Npt2a gene and both Npt2a variant transcripts are down regulated in Hyp mice.

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression


Role of membrane microdomains in PTH-mediated down-regulation of NaPi-IIa in opossum kidney cells

Parathyroid hormone (PTH) rapidly down-regulates type IIa sodium-dependent phosphate transporter (NaPi-IIa) via an endocytic pathway. Since the relationship between PTH signaling and NaPi-IIa endocytosis has not been explored, we investigated the role of membrane microdomains in this process. We examined the submembrane localization of NaPi-IIa in opossum kidney (OK-N2) cells that stably expressed human NaPi-IIa, and searched for a PTH-induced specific phosphorylating substrate on their membrane microdomains by immunoblotting with specific antibody against phospho substrates of protein kinases. We found that NaPi-IIa was primarily localized in low-density membrane (LDM) domains of the plasma membrane; PTH reduced the levels of immunoreactive NaPi-IIa in these domains. Furthermore, PTH activated both protein kinase A (PKA) and protein kinase Calpha (PKCa) and increased the phosphorylation of 250 kD and 80 kD substrates; this latter substrate was identified as ezrin, which a member of the ezrin-radixin-moesin (ERM) protein family. In response to PTH, ezrin was phosphorylated by both PKA and PKC. Dominant negative ezrin blocked the reduction in NaPi-IIa expression in the LDM domains that was induced by PTH. These data suggest that NaPi-IIa and PTH-induced phosphorylated proteins that include ezrin are compartmentalized in LDM microdomains. This compartmentalization may play an important role in the down-regulation of NaPi-IIa via endocytosis.


A pore-forming toxin produced by Aeromonas sobria activates cAMP-dependent Cl- secretory pathways to cause diarrhea

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.


血清アルブミン濃度からみたNST活動の意義と改善点

血清アルブミン濃度からみたNST活動の意義と改善点


Effect of a novel palatinose-based liquid balanced formula (MHN-01) on glucose and lipid metabolism in male Sprague-Dawley rats after short- and long-term ingestion.

Postprandial hyperglycemia and hyperinsulinemia are often present in obese subjects with glucose intolerance in whom insufficient early phase insulin secretion and subsequent delayed hyperinsulin response are observed. To address this problem, a novel palatinose-based enteral formula designated as MHN-01 was developed for the prevention of postprandial hyperglycemia and hyperinsulinemia. The effects of MHN-01 on carbohydrate and lipid metabolism in Sprague-Dawley (SD) rats were compared with those of the standard balanced formula (SBF). After a bolus intragastric injection of each formula equivalent to 0.9 g/kg carbohydrate, the peak levels of plasma glucose (PG) and insulin (IRI) in peripheral and portal veins of the MHN-01 group were significantly lower than those of the SBF group. The areas under the curve of PG and IRI in the MHN-01 group were 58.0% and 43.1% of those in the SBF group in the femoral vein and 65.0% and 69.3% in the portal vein, respectively. In the 2-month study, serum levels of IRI and triglyceride in peripheral blood in the MHN-01 group decreased and those in the SBF group increased compared with initial levels. Consequently, both levels in the MHN-01 group were significantly lower than those in the SBF group. In addition, the amount of accumulated fat in abdominal adipose tissue and liver tissue of the MHN-01 group was markedly reduced in comparison to that of the SBF group. Insulin sensitivity, evaluated as glucose infusion rate using the hyperinsulinemic euglycemic clamp technique, in the MHN-01 group was higher than that in the SBF group. Thus, in comparison to SBF, MHN-01 suppressed postprandial hyperglycemia and hyperinsulinemia, reduced visceral fat accumulation, and improved insulin sensitivity. Therefore, human study on the effects of MHN-01 on carbohydrate and lipid metabolism will be recommended to confirm whether MHN-01 may be a useful functional food for the treatment and prevention of insulin resistance.


Inorganic phosphate homeostasis and the role of dietary phosphorus.

Inorganic phosphate (Pi) is required for cellular function and skeletal mineralization. Serum Pi level is maintained within a narrow range through a complex interplay between intestinal absorption, exchange with intracellular and bone storage pools, and renal tubular reabsorption. The crucial regulated step in Pi homeostasis is the transport of Pi across the renal proximal tubule. Type II sodium-dependent phosphate (Na/Pi) cotransporter (NPT2) is the major molecule in the renal proximal tubule and is regulated by Pi, parathyroid hormone and by 1,25-dihydroxyvitamin D. Recent studies of inherited and acquired hypophosphatemia [X-linked hypophosphatemic rickets/osteomalacia (XLH), autosomal dominant hypophosphatemic rickets/osteomalacia (ADHR) and tumor-induced rickets/osteomalacia (TIO)], which exhibit similar biochemical and clinical features, have led to the identification of novel genes, PHEX and FGF23, that play a role in the regulation of Pi homeostasis. The PHEX gene, which is mutated in XLH, encodes an endopeptidase, predominantly expressed in bone and teeth, but not in kidney. FGF-23 may be a substrate of this endopeptidase and may therefore accumulate in patients with XLH. In the case of ADHR mutations in the furin cleavage site, which prevent the processing of FGF-23 into fragments, lead to the accumulation of a "stable" circulating form of the peptide which also inhibits renal Pi reabsorption. In the case of TIO, ectopic overproduction of FGF-23 overwhelms its processing and degradation by PHEX, leading to the accumulation of FGF-23 in the circulation and inhibition of renal Pi reabsorption. Mice homozygous for severely hypomorphic alleles of the Klotho gene exhibit a syndrome resembling human aging, including atherosclerosis, osteoporosis, emphysema, and infertility. The KLOTHO locus is associated with human survival, defined as postnatal life expectancy, and longevity, defined as life expectancy after 75. In considering the relationship of klotho expression to the dietary Pi level, the klotho protein seemed to be negatively controlled by dietary Pi.

Journal of Cellular and Molecular Medicine


Increase in IP3 and intracellular Ca2+ induced by phosphate depletion in LLC-PK1 cells.

The mechanisms by which Pi depletion rapidly regulates gene expression and cellular function have not been clarified. Here, we found a rapid increase in intracellular ionized calcium [Ca(2+)](i) by phosphate depletion in LLC-PK(1) cells using confocal microscopy with the green-fluorescence protein based calcium indicator "yellow cameleon 2.1." The increase of [Ca(2+)](i) was observed in the presence or absence of extracellular Ca(2+). At the same time, an approximately twofold increase in intracellular inositol 1,4,5-triphosphate (IP(3)) occurred in response to the acute Pi depletion in the medium. Furthermore, 2-aminoethoxydiphenyl borate completely blocked the [Ca(2+)](i) increase induced by Pi depletion. These results suggest that Pi depletion causes IP(3)-mediated release of Ca(2+) from intracellular Ca(2+) pools and rapidly increases [Ca(2+)](i) in LLC-PK(1) cells.

Biochemical and Biophysical Research Communications


Phosphorus supply per capita from food in Japan between 1960 and 1995

The awareness of phosphorus intake is important because hyperphosphatemia and hypophosphatemia both impair bone metabolism. Phosphorus consumption from food was obtained from values in the Food Balance Sheet (PBS) of Japan from 1960 to 1995. The amounts of phosphorus calculated from the FBS increased gradually from 1,243 mg/d in 1960 to 1,332 mg/d in 1975 and to 1,421 mg/d in 1995. This is explained by the increased consumption of cow's milk and milk products, meat, and chicken eggs. The main foods supplying phosphorus in 1995 were cereals, milk and milk products, fishes and shellfishes, and vegetables; their contributions were 24.4, 15.8, 14.2, and 10.9%, respectively. The phosphorus-to-calcium ratio calculated from the FBS was 3.51 in 1960, which decreased to 2.89 in 1975 and 2.44 in 1995. Therefore total phosphorus consumption in 1995 was presumably more than 1,500 mg/d when imported food containing phosphorus and the consumption of phosphorus-containing food additives in Japan are also considered. These findings suggest that the phosphorus consumption estimated from the FBS is increasing and that more attention should be paid to the maintenance of healthy bones in Japan, where the average amount of calcium intake is less than 600 mg/d.

Journal of Nutritional Science and Vitaminology


Hydrogen Peroxide Stimulates c-Src-mediated Big Mitogen-activated Protein Kinase 1(BMK1) and the MEF2C Signaling Pathway in PC12 Cells

Reactive oxygen species, generated by reduction-oxidation (redox) reactions, have been recognized as one of the major mediators of ischemia and reperfusion injury in the brain. Reactive oxygen species-induced cerebral events are attributable, in part, to the change in intracellular signaling molecules including mitogen-activated protein (MAP) kinases. Big MAP kinase 1 (BMK1), also known as ERK5, is a newly identified member of the MAP kinase family and has been reported to be sensitive to oxidative stress. In the present study, we examined the effect of H(2)O(2) on BMK1 activity in PC12 cells, and we investigated the pathophysiological implication of BMK1. Findings showed that BMK1 was rapidly and significantly activated by H(2)O(2) in a concentration-dependent manner in PC12 cells. BMK1 activation by H(2)O(2) was inhibited by both PD98059 and U0126, which were reported to inhibit MEK5 as well as MEK1/2. c-Src was suggested to be involved in BMK1 activation from the experiments with herbimycin A and PP2, specific inhibitors of Src family kinases. Transfection of kinase-inactive Src also inhibited H(2)O(2)-induced BMK1 activation. In addition, H(2)O(2) treatment of cells induced an enhancement of DNA binding activity of MEF2C, a downstream transcription factor of BMK1 in PC12 cells. Finally, pretreatment of cells with PD98059 and U0126 resulted in an increase in cell death including apoptosis by H(2)O(2) in ERK1/2 down-regulated cells as well as in intact PC12 cells. These findings suggest that c-Src mediated BMK1 activation by H(2)O(2) may counteract ischemic cellular damage probably through the activation of MEF2C transcription factor.


Human L-type amino acid transporter 1(LAT1):/characterization of function and expression in tumor cell lines

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential amino acids for cell growth and cellular responses, and in distributing amino acid-related compounds.

Biochimica et Biophysica Acta (BBA) - Biomembranes


) Molecular events involved in up-regulating human Na+-independent neutral amino acid transporter LAT1 during T-cell activation


Hypophosphatemic rickets accompanying McCune Albright syndrome: evidence that a humoral factor causes hypophosphatemia

McCune-Albright syndrome (MAS) is sometimes complicated by hypophosphatemia. However, it remains unclear whether a humoral factor is associated with the cause of hypophosphatemia. We isolated cells with mutations of the Gsalpha gene from fibrous bone dysplasia tissues of two MAS patients (MAS cells). Severe combined immunodeficiency (SCID) mice were subjected to experiments using from one of these cells patients. Effects of conditioned media (CM) isolated from MAS cells (MAS-CM) on phosphate transport were investigated by using rat renal slices, the renal cell line OK-B, rat intestinal rings and the human intestinal cell line Caco-2. In addition, the effects of MAS-CM on human sodium-dependent phosphate transporter (NPT2) gene promoter activity expression were investigated in the renal cell line OK-B2400 and were compared with the effects of CM isolated from a patient with oncogenic hypophosphatemic osteomalacia (OHO). MAS cells caused significant hypophosphatemia (P < 0.05) and elevated serum alkaline phosphatase activity (P < 0.05) in SCID mice. The MAS-CM significantly inhibited phosphate uptake in everted intestinal rings (P < 0.01), whereas it had no effect on glucose uptake. The MAS-CM had no effect on either phosphate uptake in the kidney or NPT2 gene promoter activity. In contrast, the CM of the OHO patient significantly inhibited phosphate uptake and NPT2 gene promoter activity. These results indicate that the humoral factor derived from fibrous dysplasia cells of the MAS patient is different to that from OHO patients, because the humoral factor from the MAS patient inhibited phosphate transport not in the kidney but in the intestine.


A neutrophil elastase inhibitor (ONO-5046) reduces neurologic damage after spinal cord injury in rats

In view of a cytoprotective effect of elastase inhibitor on chemokine-mediated tissue injury, we examined the neuroprotective effect of ONO-5046, a specific inhibitor of neutrophil elastase, in rats with spinal cord injury. Standardized spinal cord compression markedly increased cytokine-induced neutrophil chemo-attractant (CINC)-1 mRNA and protein. Their increases correlated with neurologic severity of injured rats. Immunohistochemically, CINC-1 protein was detected sequentially in vascular endothelial cells at 4 h, in perivascular neutrophils at 8 h, and in neutrophils infiltrating into cord substance at 12 h. Pretreatment with ONO-5046 (50 mg/kg) markedly ameliorated motor disturbance in injured rats, and reduced CINC-1 protein and mRNA expression. ONO-5046 also significantly reduced the increase of neutrophil accumulation or infiltration estimated by myeloperoxidase activity, and the extent of vascular permeability by Evans blue extravasation in the injured cord segment in comparison to control animals receiving vehicle. These results suggest that CINC-1 contributed to inflammation in rat spinal cord injury and ONO-5046 attenuated neurologic damage partly by blocking CINC-1 production of the chemoattractant, preventing neutrophil activation and vascular endothelial cell injury.


Direct demonstration of humorally mediated inhibition of the transcription of phosphate transporter in XLH patients


The polymorphism in the caudal-related homeodomain protein Cdx-2 binding element in the human vitamin D receptor gene


Regulation of intestinal Na+-dependent phosphate co-transporters by a low-phosphate diet and 1,25-dihydroxyvitamin D3.


Daily pattern of energy metabolism in cirrhosis.

The daily pattern of energy expenditure and the oxidation rates of carbohydrates, fats, and protein were evaluated by indirect calorimetry in 18 control subjects (Group 1) and 34 cirrhotic patients who were divided into Groups 2a and 2b showing indocyanin green retention rates at 15 min of <30% and 30% or more, respectively. The ratio of resting energy expenditure to basal energy expenditure (%REE) was higher in the cirrhotic patients than in the controls at 8:30 AM and 2:30 PM. The oxidation rates of carbohydrates and fats under fasting conditions in Group 2b patients were respectively lower, and higher than in Group 1 and 2a patients. After the subjects ate, glucose became the substrate preferentially metabolized, and the proportion of fat metabolized was reduced from 82.9+/-5.1% to 43.9+/-21.9% and from 70.7+/-14.1% to 46.8+/-13.9% in the patients with advanced and less advanced cirrhosis, respectively, and from 59.4+/-27.2% to 48.4+/-18.5% in the controls. The fasting concentrations of non-esterified fatty acids in Group 2b were also significantly higher than those in the Group 1 and Group 2a patients. After eating, these concentrations fell and reached similar levels in the patients and controls. These data indicated that the patients with cirrhosis developed the catabolic state of starvation in the morning because of a lack of glycogen stores. Therefore, frequent meal supplementation to prevent early-onset starvation and energy deficiency may be advisable in such patients to maintain a well-nourished condition.


A vitamin D receptor gene polymorphism in the translation initiation codon: effect on protein activity and relation to bone mineral density in Japanese women.


Acute regulation by dietary phosphate of the sodium-dependent phosphate transporter (NaP(i)-2) in rat kidney.


Vitamin D3 elicits calcium response and activates blood monocyte-derived macrophages from patients with vitamin D dependent rickets type II.


Vitamin D3 elicits calcium response and activates blood monocyte-derived macrophages from patients with vitamin D dependent rickets type 2


最前線 慢性腎臓病の合併症とlipotoxicity

最前線 慢性腎臓病の合併症とlipotoxicity


食餌性リンによる血管障害

食餌性リンによる血管障害


Association with Fetuin-A and Ectopic Calcification in -Klotho Mutant Mice.

American Society of Nephrology Kidney Week 2013, Atlanta, USA


Hyperphosphatemia and hyperparathyroidism, frequently observed in patients with endstage renal disease, are associated with renal osteodystrophy, organ calcification, cardiovascular disease and sudden death. Restriction of dietary protein and phosphorus is beneficial in slowing the progression of renal failure. Dietary phosphorus restriction must be prescribed at all stages of renal failure in adults. It may be achieved by decreasing protein intake and avoiding foods rich in phosphorus. An average of 60-80% of the phosphorus intake is absorbed in the gut in dialysis patients. If phosphate binders are employed, the phosphorus absorbed from the diet may be reduced to 40%. Conventional hemodialysis with a high-flux, high-efficiency dialyzer removes approximately 30 mmol (900 mg) phosphorus during each dialysis performed three times weekly. Therefore, 750 mg of phosphorus intake should be the critical value above which a positive balance of phosphorus may occur. This value corresponds to a protein diet of 45-50 g/day or 0.8 g/kg body weight/day for a 60 kg patient. Target levels should become 9.2-9.6 mg/dl for calcium, 2.5-5.5 mg/dl for phosphorus, <55 mg2/dl2 for the calcium-phosphorus product, and 100-200 pg/ml for intact parathyroid hormone.


Gene expression in low glycemic index diet - impact on metabolic control.

Correcting postprandial hyperglycemia forms an important part of the prevention and management of type 2 diabetes. A low-glycemic-index liquid formula designated as Inslow was prepared by replacing dextrin in the standard balanced formula (SBF) with 55.7% palatinose. Long-term administration of Inslow prevented fatty liver and improved insulin resistance in rats. Expressions of mRNA of factors involved in glucose and lipid metabolism were determined to clarify its mechanism. Analysis of mRNA expressions revealed that Inslow increased the expression of enzymes involved in Beta -oxidation and peroxisome proliferator-activated receptor-alpha (PPAR-alpha) in the liver, and increased PPAR-gamma, adiponectin and uncoupling protein 2 as well as decreased tumor necrosis factor alpha in adipose tissue in comparison with those of SBF. Inslow may induce improvement of insulin resistance by accelerated Beta-oxidation through increased expression of the hepatic PPAR-alpha gene and adipocyte PPAR-gamma gene. Therefore, Inslow is a functional food which prevents and treats type 2 diabetes.


SF-36を用いた肝硬変患者におけるLES療法長期継続効果の検討

SF-36を用いた肝硬変患者におけるLES療法長期継続効果の検討


Chylous ascites complicating perinatal severe hypophosphatasia in an infant on high-setting ventilation and enzyme replacement therapy.