Association of Circulatory Iron Deficiency With an Enlarged Heart in Patients With End-Stage Kidney Disease.

OBJECTIVES: High prevalence of iron deficiency (ID) and cardiomyopathy have been observed in patients with end-stage kidney disease (ESKD). Our objective was to clarify associations between ID and cardiac remodeling in patients with ESKD. DESIGN AND METHODS: A cross-sectional study was conducted using 1974 Japanese patients with ESKD at the initiation of maintenance dialysis. Levels of hemoglobin (Hb), iron status, and cardiac enlargement as assessed by the cardiothoracic ratio (CTR) were determined immediately before the first hemodialysis session. Circulatory ID was defined as transferrin saturation (TSAT) < 20%, and stored ID was defined as ferritin level <100 ng/dL. RESULTS: The mean age was 67 years. Median CTR was 54.0%. The prevalence of circulatory and stored ID was found to be 38% and 34%, respectively. CTR was higher in patients with circulatory ID than in those without. Even in ESKD patients without overhydration, significant negative association was observed between TSAT and CTR. Higher odds ratios in parallel with higher CTR categories compared with the reference category of CTR <45% were found in patients with TSAT <20% on multinomial analysis, but ferritin did not show any significant associations. The odds ratio for CTR >54% showed an upward trend in patients with TSAT <20% (odds ratio: 1.3) and <10% (odds ratio: 1.6) compared with the reference, even after adjusting for confounding variables such as Hb and ferritin. However, that phenomenon was eliminated by adding usage of an iron agent. CONCLUSIONS: Circulatory ID is closely associated with an enlarged heart independent of ferritin and Hb. Iron supplementation in the predialysis phase of chronic kidney disease may prevent cardiac remodeling independent of Hb level in patients chronic kidney disease.

Possible prevention of uremic nausea by vitamin D receptor activators in non-dialysis patients with stage 5 chronic kidney disease.

BACKGROUND: Nausea is a major uremic symptom and a frequent indication for starting dialysis. However, preventive medication for uremic nausea has not yet been identified. Vitamin D receptor activators (VDRAs) may prevent uremic nausea via their pleiotropic actions. The objective of this study was to explore whether VDRA administration during the predialysis period is associated with a reduced prevalence of uremic nausea just prior to beginning dialysis. METHODS: A multicenter, retrospective, cross-sectional study was performed to identify a medication to prevent uremic nausea. Patients with stage 5 CKD who were followed-up over 3 months were included. The primary outcomes examined were the prevalence of uremic nausea, congestive heart failure (CHF), and intractable edema at dialysis commencement. The predictor variable was VDRA use during the predialysis period. RESULTS: One thousand five hundred and thirty six patients who had just begun dialysis in nine Japanese facilities between January 2006 and October 2013 were included. Two hundred and thirty (15.0%) patients had commenced dialysis because of uremic nausea, and three hundred and ninety two (25.5%) patients had been using VDRAs before initiating dialysis. Logistic regression analysis showed that, among the medications examined in this study, only VDRA use was independently associated with a lower frequency of uremic nausea (OR 0.512, 95% CI 0.347-0.738, P = 0.0003). On the other hand, CHF and intractable edema were not associated with VDRA administration. CONCLUSION: Use of VDRAs during the predialysis period was the only factor associated with a lower prevalence of uremic nausea, suggesting that VDRAs may prevent uremic nausea in patients with advanced CKD.

Effects of Cyclophosphamide Pulse Therapy on the Clinical and Histopathological Findings, Particularly Crescent Formation, in a Patient with Adult-onset Steroid-refractory Henoch-Schönlein Purpura Nephritis.

A 29-year-old woman was diagnosed with Henoch-Schönlein purpura nephritis (HSPN) based on the presence of purpura and histopathological findings showing crescent formation, mesangial proliferation and IgA deposition in the glomerular mesangium. She was treated with high-dose steroids; however, the nephritic syndrome persisted. Therefore, we diagnosed her with steroid-resistant HSPN and decided to add treatment with cyclosphamide pulse therapy. After one year of treatment, the histopathological findings, including crescent formation and IgA deposition, improved, as confirmed on a renal biopsy, and the patient fulfilled the criteria for complete remission. Cyclophosphamide pulse therapy may be considered an effective treatment for intractable HSPN.

Possible prevention of dialysis-requiring congestive heart failure by angiotensin-II receptor blockers in non-dialysis Japanese patients with Stage 5 chronic kidney disease.

BACKGROUND: Preventive medications for dialysis-requiring congestive heart failure (CHF) in non-dialysis Japanese patients with Stage 5 chronic kidney disease (CKD) are unknown. Our aim was to explore which CKD medication was associated with a reduced prevalence of dialysis-requiring CHF in non-dialysis Japanese patients with Stage 5 CKD. METHODS: The present multicenter, retrospective, cross-sectional study examined the association between CKD medications and the prevalence of dialysis-requiring CHF in non-dialysis Japanese patients with Stage 5 CKD. RESULTS: There were 1536 Japanese Stage 5 CKD patients who satisfied our inclusion criteria. We had 309 (20.1%) patients whom had developed dialysis-requiring CHF and 940 patients (60.8%) whom had been using angiotensin-II receptor blockers (ARBs) before initiating dialysis. In our multivariate analysis, only ARB use was significantly associated with a lower risk of CHF (Odds ratio (OR): 0.680, 95% confidence interval (CI): 0.516-0.897; p = 0.0064), of the CKD treatments examined in this study. CONCLUSIONS: We found that ARB use during the pre-dialysis period is associated with a lower prevalence of CHF in the non-dialysis Japanese patients with Stage 5 CKD, suggesting a possible prevention of dialysis-requiring CHF by ARBs, in non-dialysis Japanese patients with Stage 5 CKD.

Electron Microscopy and X-ray Analysis of Cr-Containing Precipitates Synthesized by Newly Isolated Actinobacterium, Flexivirga alba ST13(T.).

Chromium(Cr) precipitate synthesized by Cr(VI)-reducing bacterium Flexivirga alba ST13(T) was examined using transmission electron microscopy (TEM) and the energy dispersive X-ray (EDX). The strain showed altered-morphology after exposing to Cr(VI) in minimal medium. The resultant precipitate included bacterial pellet and needle-like structure which was similar to the structure made from Cr(OH)3 precipitate. Cr was observed in bacterial cells using TEM-EDX. Bacteria with high electron density showed the precipitation of Ca in addition to Cr. The isolated strain would be useful to precipitate Cr from Cr(VI)-containing environment.

Significance of serum magnesium as an independent correlative factor on the parathyroid hormone level in uremic patients.

CONTEXT: PTH is a critical factor in mineral homeostasis, and chronic kidney disease mineral and bone metabolism disorder is a very important problem in patients with renal failure. Abnormal levels of PTH, serum phosphate, and calcium influence chronic kidney disease mineral and bone metabolism disorder, but there is little information about the influence of magnesium (Mg) on PTH. OBJECTIVE: The aim of this study was to elucidate the correlation between magnesium and PTH levels in uremic patients just prior to beginning hemodialysis (HD) for the first time. PATIENTS: We enrolled 1231 patients in nine Japanese facilities who had begun HD for end-stage renal disease. We investigated their serum Mg levels and the correlation between intact PTH (iPTH) and the serum Mg levels and other clinical parameters and medications. RESULTS: The mean serum Mg was 2.2 ± 0.5 mg/dL, and hypermagnesemia was found in 663 patients (53.9%). Divided into two groups according to median iPTH level, the serum Mg levels were significantly higher in patients with low iPTH (2.3 ± 0.5 vs 2.1 ± 0.5, P < .01). Furthermore, divided into two groups according to the Mg level, iPTH levels were lower in patients with high Mg than in patients with normal serum Mg levels (277.9 ± 195.9 pg/mL vs 321.9 ± 203.7 pg/mL, P < .01). In the multiple regression analysis according to the effect of iPTH level, the serum Mg level was an independent variable after adjustment for other factors. CONCLUSIONS: A high serum level of Mg is frequent in uremic patients with end-stage renal disease just prior to beginning HD. In the present set of patients, there was a significant correlation between the serum Mg and iPTH levels. Furthermore, the serum Mg level was an independent factor apart from the other factors regulating iPTH. These results suggest that serum Mg may be one of the factors regulating the serum PTH level in uremic patients.

Isolation of a selenite-reducing and cadmium-resistant bacterium Pseudomonas sp. strain RB for microbial synthesis of CdSe nanoparticles.

Bacteria capable of synthesizing CdSe from selenite and cadmium ion were enriched from a soil sample. After repeated transfer of the soil-derived bacterial cultures to a new medium containing selenite and cadmium ion 42 times (during 360 days), an enrichment culture that can simultaneously remove selenite and cadmium ion (1 mM each) from the liquid phase was obtained. The culture's color became reddish-brown, indicating CdSe nanoparticle production, as confirmed by energy-dispersive x-ray spectra (EDS). As a result of isolation operations, the bacterium that was the most responsible for synthesizing CdSe, named Pseudomonas sp. RB, was obtained. Transmission electron microscopy and EDS revealed that this strain accumulated nanoparticles (10-20 nm) consisting of selenium and cadmium inside and on the cells when cultivated in the same medium for the enrichment culture. This report is the first describing isolation of a selenite-reducing and cadmium-resistant bacterium. It is useful for CdSe nanoparticle synthesis in the simple one-vessel operation.

Association between the Hemoglobin Level and Cardiothoracic Ratio in Patients on Incident Dialysis.

BACKGROUND/AIM: The present study explores associations between hemoglobin (Hb) levels and patients with cardiac enlargement in end-stage kidney disease (ESKD) to help prevent cardiac remodeling during the predialysis phase of chronic kidney disease (CKD). METHODS: This cross-sectional study included 2,249 patients with ESKD (age, 67 ± 13 years; male, 67%; diabetic kidney disease, 41%) who started hemodialysis (HD) between January 2006 and October 2013 at eight participating hospitals. We examined associations between Hb levels immediately before the first HD session and cardiothoracic ratios (CTRs). Clinical factors associated with the CTR were also assessed. RESULTS: The mean Hb level was 8.7 ± 1.6 g/dl, and the mean and median CTRs were 55.0 and 54.7%, respectively. The correlation between the Hb level and the CTR was linear and negative (r = -0.129, p < 0.001). The mean CTR and the prevalence of patients with a CTR >50% obviously decreased with increasing Hb levels (both p < 0.001 for trend). Univariate logistic regression analysis revealed an approximately 20% reduction in the odds ratio for complicating CTRs >50% per 1 g/dl increase in Hb. Hb levels of <9 g/dl were significantly associated with CTRs >50%. Numerical and categorical Hb remained significantly associated with CTRs >50% after adjusting for confounding variables. CONCLUSIONS: Lower Hb levels participate in progressive CTR enlargement in patients with ESKD, and maintaining Hb levels of >9 g/dl might help prevent cardiac remodeling during the predialysis phase of CKD.

Need for education on the differential diagnosis between chronic glomerulonephritis and nephrosclerosis, and treatment of both conditions to reduce the number of patients requiring hemodialysis in Wakayama.

OBJECTIVE: We investigated the present state of, and trends in, hemodialysis therapy in Wakayama, with the aim of identifying present and future problems. METHODS: We compared the number of patients on maintenance hemodialysis, patients newly commencing hemodialysis each year, and proportion of diseases prompting the initiation of hemodialysis, between Wakayama and all Japan from 2002 to 2009, using the CD-ROM, "An overview of dialysis treatment in Japan," published by the Japanese Society for Dialysis Therapy. RESULTS: The number of patients on maintenance hemodialysis per head of population was higher in Wakayama than in all Japan throughout the study period. The number of patients newly commencing hemodialysis per head of population was higher in Wakayama than in all Japan from 2002 to 2004, but no significant difference was seen after 2005. The proportion of patients with chronic glomerulonephritis as the causative disease for hemodialysis initiation was higher in Wakayama than in all Japan. However, nephrosclerosis was less common as the causative condition in Wakayama than in all Japan. The proportions of the different causative diseases were similar in all patients on maintenance hemodialysis in Wakayama as in the newly initiated patients. Accordingly, some patients diagnosed with chronic glomerulonephritis might actually have nephrosclerosis, or treatment may be inadequate. CONCLUSION: In order to reduce the number of patients requiring maintenance hemodailysis, it is important to accurately differentiate between chronic glomerulonephritis and nephrosclerosis, and also to treat patients with either disease appropriately.

The management of hyperphosphatemia by lanthanum carbonate in chronic kidney disease patients.

Hyperphosphatemia has been shown to be involved not only in the onset and progression of secondary hyperparathyroidism but also in vascular calcification. In addition, it influences the clinical course of patients with chronic kidney disease. Phosphate (Pi) binder is required in the management of hyperparaphosphatemia, because dietary Pi restriction and Pi removal by hemodialysis alone are insufficient. Lanthanum carbonate, a powerful Pi binder, has a similar effect to aluminum hydroxide in reducing serum Pi levels. As it is excreted via the liver, lanthanum carbonate has an advantage in patients with renal failure. The effect of lanthanum carbonate on serum Pi levels is almost two times higher than that of calcium (Ca) carbonate, which is commonly used. Lanthanum carbonate and Ca carbonate have an additive effect. Worldwide, there is 6 years worth of clinical treatment data on lanthanum carbonate; however, we have 3 years of clinical use in Japanese patients with hyperphosphatemia. No serious side effects have been reported. However, the most important concern is bone toxicity, which has been observed with use of aluminum hydroxide. For this study, clinical research involved analysis of bone biopsies. Although osteomalacia is the most noticeable side effect, this was not observed. Both the high- and the low-turnover bone disease concentrated into a normal bone turnover state. However, as the authors have less than 10 years' clinical experience with lanthanum carbonate, patients should be monitored carefully. In addition, it is necessary to demonstrate whether potent treatment effects on hyperphosphatemia improve the long-term outcome.

Effect of erythropoietin-stimulating agent on uremic inflammation.

BACKGROUND: The goal of the present study was to explore the effect of medications that are commonly prescribed for CKD patients on uremic state. METHODS: This was a cross-sectional study. From January 2006 to October 2009, 1,623 patients with end-stage kidney disease (ESKD) commenced hemodialysis (HD) at the 9 participating hospitals. The criteria for exclusion from the database were 1) serum C-reactive protein (CRP) > 3 mg/dL, 2) WBC count > 9,000/mm3 or <4,000/mm3, and 3) patients with cancer, immune complex disease, or vasculitis. A total of 900 patients were entered into the final database. We explored the association of serum CRP just before the first HD session with clinical characteristics, laboratory data, and medications for CKD in the predialysis period. RESULTS: On univariate analysis, age, CTR, eGFR, and WBC were significantly correlated with CRP. Systolic and diastolic blood pressure, serum albumin, LDL-C, HDL-C, Hb, Cr, and Ca were inversely associated with CRP. Use of erythropoietin-stimulating agents (ESA) using (r = -0.111, p = 0.0015), renin-angiotensin-aldosterone system inhibitors (r = -0.083, p = 0.0154), and calcium channel blockers (r = -0.1, p = 0.0039) was also negatively correlated with CRP. However, only use of ESA showed a significant negative correlation with CRP that was independent of other clinical factors and CKD medications on multiple regression analysis. CONCLUSION: ESA may strongly reduce uremic inflammation in addition to improving anemia. To confirm this potential effect, a large-scale longitudinal study would be required.

Influence of renin-angiotensin system on serum parathyroid hormone levels in uremic patients.

INTRODUCTION: The aim of this study was to investigate the factors influencing serum parathyroid (PTH) levels, including medications for treating chronic kidney disease-mineral and bone metabolism disorder (CKD-MBD) in patients with end-stage renal disease. METHODS: We enrolled 1,076 patients in nine Japanese facilities who had begun hemodialysis (HD) due to ESRD. We investigated the relationships between intact PTH (iPTH) levels and clinical parameters and medications just prior to beginning HD. RESULTS: Significant decreases in serum iPTH levels were seen in males, in the presence of diabetes mellitus (DM), and with administration of renin-angiotensin system inhibitors (RASIs). Significant correlations were found between serum calcium and iPTH levels. In the patients administered RASIs, there was a significant decrease in serum iPTH levels with DM, male gender, and administration of active vitamin D sterols (VDs) compared with those not administered RASIs, although serum-corrected calcium levels were not different. Multiple regression analysis found gender, age, presence of DM, and serum calcium and phosphate levels to be significant contributing factors. In addition, administration of angiotensin II receptor blockers (ARBs) may also be a contributing factor to iPTH levels at the beginning HD (p = 0.050). CONCLUSIONS: In this study, serum iPTH levels were related to administration of ARBs besides gender, age, the presence of DM and serum calcium levels. Our study suggests that the RA system involve serum iPTH levels in uremic patients.

Development of a genetic transfer system in selenate-respiring bacterium Citrobacter sp. strain JSA which was isolated from natural freshwater sediment.

Conjugative mating between the selenate-reducing bacterium Citrobacter sp. strain JSA and Escherichia coli S17-1 harboring the broad-host-range plasmid pKT230 or pKT240 (IncQ) allowed genetic transfer to strain JSA at a maximum frequency of 2.5×10(-5) (pKT230) and 5.1×10(-6) (pKT240) per recipient JSA cell. Kanamycin-resistant (selection marker of pKT230 and pKT240) transconjugants were routinely obtained with this method, and we confirmed that both vectors were also successfully transferred and replicated in strain JSA without alteration of the replicon. Furthermore, an electroporation method has also allowed transformation of JSA at a frequency of 10(-7) to 10(-6) transformants per µg vector DNA (per recipient cell), and PCR and hybridization analyses revealed that pKT230 and pKT240 are stably maintained in transformed JSA cells. These results indicated that both InQ plasmids can be used as vectors for gene transfer to selenate-reducing strain JSA. This is the first study to demonstrate an effective method for genetic transfer in a selenate-reducing Citrobacter bacterium and will aid in the elucidation of the selenium oxyanion reduction mechanism in this genus of environmental selenate-respiring isolates.

Fibroblast growth factor 23 production in bone is directly regulated by 1{alpha},25-dihydroxyvitamin D, but not PTH.

Fibroblast growth factor 23 (FGF23), which is primarily produced by osteocytes in bone, regulates renal phosphate excretion and 1α,25-dihydroxyvitamin D [1,25(OH)(2)D(3)] metabolism. Patients with chronic kidney disease (CKD) have increased levels of circulating serum FGF23, but the direct effect on circulating FGF23 levels in renal insufficiency is still unclear. To identify the major regulator of FGF23 synthesis in renal insufficiency, we compared the effect of parathyroid hormone (PTH) and 1,25(OH)(2)D(3) on FGF23 synthesis in the calvariae of normal rats with that of uremic rats in vitro. 1,25(OH)(2)D(3) treatment significantly increased the FGF23 concentration in the medium from both groups, but the degree of increase in the uremic group was markedly higher than in the control group. A significant increase in FGF23 mRNA expression occurred as early as 4 h after treatment and reached the maximum within 8 h in the uremic group, whereas in the normal group a significant increase in FGF23 mRNA expression was observed only at 8 h. In addition, the expression of vitamin D receptor (VDR) mRNA in the calvariae of uremic rats was markedly higher than in normal rats. However, in neither group did PTH treatment affect the medium FGF23 concentration or the FGF23 mRNA levels. These results suggest that FGF23 synthesis in bone is regulated by 1,25(OH)(2)D(3) directly, not by PTH, and that increased VDR mRNA expression induced the relatively swift and strong response in the uremic group.

Reduced expression of perlecan in the aorta of secondary hyperparathyroidism model rats with medial calcification.

BACKGROUND: Vascular calcification is an important complication that worsens the prognosis for dialysis patients, although its detailed molecular mechanisms are still unknown. METHODS: We produced a rat model for vascular calcification with hyperphosphatasemia and hyperparathyroidism, performing a 5/6 nephrectomy and providing a high-phosphorus, low-calcium diet for eight weeks. We examined mRNA obtained from the calcified aortae using microarray analysis, and searched for alterations in gene expression specifically in the calcified lesions. RESULTS: Medial calcification was demonstrated in the abdominal aorta of 12 out of 42 hyperparathyroidism rats. In the aortae of hyperparathyroid rats with vascular calcification, the genes for heparan sulfate proteoglycans, including perlecan, were found to be down-regulated using microarray analysis and real time PCR. Immunohistochemistry also demonstrated reduced production of perlecan in the aortae of hyperparathyroid rats. DISCUSSION: Perlecan is a major component of the vascular wall basement membrane and may play a role in protecting vascular smooth muscle cells from inflammatory cells and various toxins. It has also been reported that heparan sulfate chains may inhibit osteogenesis. Our findings indicate that perlecan may protect vascular smooth muscle cells from various factors that promote vascular calcification. CONCLUSIONS: It may be that reduced expression of perlecan in the calcified aortae of hyperparathyroid rats is a risk factor for vascular calcification.

Mechanism of phosphate-induced calcification in rat aortic tissue culture: possible involvement of Pit-1 and apoptosis.

BACKGROUND: Hyperphosphataemia is a known contributing factor in the progression of vascular calcification in dialysis patients. The cellular mechanisms underlying phosphate-induced calcification are still unclear despite intense study, so in this study, we investigated the possible involvement of the type III sodium-dependent phosphate cotransporter, Pit-1, in an aortic tissue culture model. METHODS: Aortic segments from 9-week-old male Sprague-Dawley rats were incubated in serum-supplemented medium for 10 days. The phosphate concentration of the medium was elevated to induce calcification, which was assessed by histology and calcium content. Phosphonoformic acid (PFA) was used to inhibit phosphate uptake. The involvement of apoptosis was examined using the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate (dUTP) nick-end labelling (TUNEL) assay, caspase 3 activation, and inhibition of apoptosis using a general caspase inhibitor. Phenotypic changes in vascular smooth muscle cells (VSMC) were assessed using expression of osteochondrogenic differentiation markers. RESULTS: Medial vascular calcification was induced in aortas cultured in a high phosphate medium. PFA decreased the rates of calcification and apoptosis of VSMC in the media, concomitant with calcification. Caspase inhibitor reduced calcification. No phenotypic transition of VSMC was seen in this model. CONCLUSIONS: These results indicate that phosphate uptake through the type III sodium-dependent phosphate cotransporter, Pit-1, leads to induction of apoptosis and subsequent calcification of VSMC.

Improvement of impaired calcium and skeletal homeostasis in vitamin D receptor knockout mice by a high dose of calcitriol and maxacalcitol.

Vitamin D plays a major role in mineral and skeletal homeostasis through interaction with the nuclear vitamin D receptor (VDR) of target cells. Recent reports have indicated that some cellular effects of vitamin D may occur via alternative signaling pathways, but concrete evidence for mineral homeostasis has not been shown in vivo. To investigate this issue, the actions of calcitriol (1,25D) and maxacalcitol (OCT), which were developed for treatment of uremia-induced secondary hyperparathyroidism, were analyzed in VDR knockout (VDR(-/-)) mice. The VDR(-/-) mice were fed a rescue diet immediately after weaning. 1,25D, OCT or a control solution was administered intraperitoneally to these mice three times a week for eight weeks. Biological markers and bone growth were measured and bone histomorphometric analysis of the calcein-labeled tibia was performed 24 h after the final administration. Significantly higher levels of serum Ca(2+) were observed in 1,25D- and OCT-treated mice, but the serum parathyroid hormone level was unchanged by both agents. Impaired bone growth, enlarged and distorted cartilaginous growth plates, morphological abnormalities of cancellous and cortical bones; a morbid osteoid increase, lack of calcein labeling, and thinning of cortical bone, were all significantly improved by 1,25D and OCT. The significance of these effects was confirmed by bone histomorphometrical analysis. Upregulation of the calbindin D(9k) mRNA expression level in the duodenum may explain these findings, since this protein is a major modulator of Ca transport in the small intestine. We conclude that 1,25D and OCT both at a high dose exert significant effects on Ca and skeletal homeostasis with the principal improvement of Ca status in VDR(-/-) mice, and some of these effects may occur through an alternative vitamin D signaling pathway.

Tolvaptan, a selective oral vasopressin V2 receptor antagonist, ameliorates podocyte injury in puromycin aminonucleoside nephrotic rats.

BACKGROUND: Proteinuria caused by glomerular disease is characterized by podocyte injury. Vasopressin V2 receptor antagonists are effective in reducing albuminuria, although their actions on glomerular podocytes have not been explored. The objective of this study was to evaluate the effects of tolvaptan, a selective oral V2 receptor antagonist, on podocytes in a puromycin aminonucleoside (PAN)-induced nephrosis rat model. METHODS: Rats were allocated to a control, PAN nephrosis, or tolvaptan-treated PAN nephrosis group (n = 9 per group). Urinary protein excretion and serum levels of total protein, albumin, creatinine, and total cholesterol were measured on day 10. The influence of tolvaptan on podocytes was examined in renal tissues by immunofluorescence and electron microscopy. RESULTS: PAN induced massive proteinuria and serum creatinine elevation on day 10, both of which were significantly ameliorated by tolvaptan. Immunofluorescence studies of the podocyte-associated proteins nephrin and podocin revealed granular staining patterns in PAN nephrosis rats. In tolvaptan-treated rats, nephrin and podocin expressions retained their normal linear pattern. Electron microscopy showed foot process effacement was ameliorated in tolvaptan-treated rats. CONCLUSIONS: Tolvaptan is protective against podocyte damage and proteinuria in PAN nephrosis. This study indicates that tolvaptan exerts a renoprotective effect by affecting podocyte morphology and probably function in PAN nephrosis. Tolvaptan is a promising pharmacological tool in the treatment of renal edema.

Regulation of fibroblast growth factor 23 production in bone in uremic rats.

BACKGROUND: Fibroblast growth factor 23 (FGF23) regulates renal phosphate reabsorption and 1alpha,25-dihydroxyvitamin D [1,25(OH)(2)D(3)] metabolism. Patients with chronic kidney disease (CKD) have increased levels of circulating FGF23, but the direct regulation of this elevation of FGF23 is incompletely understood. METHOD: We measured plasma parameters in uremic rats fed a high-phosphorus diet and then performed parathyroidectomy (PTX) to determine its effect. We also investigated FGF23 mRNA expression in various tissues to identify the major source of circulating FGF23. RESULT: The uremic rats displayed dramatic changes in plasma FGF23 levels, consistent with increased expression of FGF23 in bone. Elevated FGF23 was associated with phosphate and parathyroid hormone (PTH). After PTX, the elevated FGF23 had decreased, consistent with decreased expression of FGF23 in bone. Significant decreases in plasma FGF23 were associated with PTH and 1,25(OH)(2)D(3), but not phosphate. CONCLUSION: Elevated plasma FGF23 levels in uremic rats reflect the increased expression of FGF23 in bone. The expression of FGF23 in bone may be regulated by a PTH-1,25(OH)(2)D(3) axis-dependent pathway and another PTH-dependent and 1,25(OH)(2)D(3)-independent pathway in uremic rats. The pathway may be decided by the degree of renal dysfunction.

Conjugal transformation and transposon and chemical mutagenesis of gram-negative selenate-respiring Citrobacter sp. strain JSA.

Conjugal mating between selenate-reducing Citrobacter sp. strain JSA and Escherichia coli S17-1 bearing pSUP2021 allowed transposon mutagenesis and chromosomal transformation. Kanamycin-resistant transconjugants were obtained successfully by this method from a freshwater selenate-respiring Citrobacter sp. strain JSA. The maximum frequency of kanamycin-resistant Tn5 transconjugants was 3.6 x 10(-6) per recipient of this strain. Of these transconjugants, eight strains of selenate reduction-deficient transconjugants living by nitrate reduction were obtained in the strain JSA. Moreover, the same phenotype of deficient mutant was created by chemical mutagenesis with ethylmethanesulfonate. The results strongly indicate that selenate reducing anaerobic respiration was independent of nitrate reduction in the Citrobacter sp. isolate strain JSA.