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Biomedical subjects

Atsushi Fukatsu

Publications and source records attributed to Atsushi Fukatsu.

At least 19 recordsLinked to original sources

Roles of coagulation pathway and factor Xa in rat mesangioproliferative glomerulonephritis.

Tissue factor initiates the extrinsic coagulation pathway by activating coagulation factor X to factor Xa, and factor V is a cofactor for the prothrombin activation by factor Xa. As factor Xa is known to promote the proliferation of mesangial cells in culture, the roles of the coagulation pathway and factor Xa were studied in an animal model of mesangioproliferative glomerulonephritis (MsPGN). MsPGN was induced in Wistar rats by an intravenous injection of anti-Thy 1.1 monoclonal antibody, OX-7. To clarify the role of factor Xa in MsPGN, a specific factor Xa inhibitor, DX-9065a, was injected intravenously at 2.5 or 10 mg/kg at the same time as OX-7, and kidney involvement was assessed by immunohistological analyses. We also examined p44/42 mitogen-activated protein (MAP) kinase activation. Time-course study revealed that expressions of tissue factor, factor V, and protease-activated receptor 2 (PAR2) were peaked on day 3, followed by factor X accumulation and mesangial proliferation. DX-9065a treatment significantly ameliorated proteinuria in a dose-dependent manner on day 8. Histological analyses showed a significant reduction in the size of glomeruli, the total number of glomerular cells, and crescent formation by DX-9065a treatment. Macrophage infiltration, which was rapidly observed on day 1 in disease control rats was not inhibited on days 1-3 by DX-9065a treatment, however it was suppressed on days 5-8. The deposition of fibrin, the number of PCNA-positive cells, and phosphorylation of p44/42 MAP kinase were markedly increased in the disease control group, whereas they were significantly reduced in the treatment group. Tissue factor and factor V induction may accelerate MsPGN through the activation and accumulation of factor X via proinflammatory and procoagulant mechanisms, and the inhibition of factor Xa would be a promising method to regulate the disease process.

Analysis of Variance↗

Angiotensin II-dependent Src and Smad1 signaling pathway is crucial for the development of diabetic nephropathy.

Angiotensin II (Ang II) is known to play a pivotal role in the development of diabetic nephropathy. However, the precise mechanism of Ang II-mediated effects on diabetic nephropathy is still unknown. We have reported that Smad1 plays a key role in diabetic mesangial matrix expansion and directly regulates the transcription of type IV collagen (Col4) in vitro and in vivo. Here we examined the effect of Ang II on the expression of Smad1 and mesangial matrix expansion in streptozotocin (STZ)-induced diabetic rats in vivo, using Ang II type 1 receptor blocker, olmesartan. We also examined the signaling mechanism by which Ang II induces mesangial matrix expansion in vitro. Treatment of diabetic rats with low-dose olmesartan for 20 weeks reduced albuminuria and hyperfiltration without affecting blood pressure and inhibited mesangial matrix expansive changes and the expression of Col4 and smooth muscle alpha actin compared with those in untreated rats. Immunohistochemical staining and Western blotting showed that the increased expression of Smad1, phospho-Smad1, and phospho-Src was inhibited by olmesartan. Ang II induced Col4 synthesis and increased expression of phospho-Src and phospho-Smad1 in cultured mesangial cells, which was blocked by olmesartan. PP2, a Src tyrosine kinase inhibitor, and overexpression of dominant negative Src also reduced the phosphorylation of Smad1. Moreover, addition of small-interfering RNA against Src significantly reduced the phosphorylation of Smad1 and synthesis of Col4. Taken together, these results indicate that Ang II can regulate the development of mesangial matrix expansion in the early phase of diabetic nephropathy through Src and Smad1.

Angiotensin II↗

IgM-immune complex glomerulonephritis associated with sarcoidosis.

We present a case of proliferative glomerulonephritis with peculiar IgM deposition associated with sarcoidosis. A 62-year-old woman, who had been diagnosed with sarcoidosis 3 years previously because of abnormalities on chest X-ray radiophotographs and lymph node pathology, was admitted to our hospital for the evaluation of proteinuria and microscopic hematuria. Laboratory findings showed renal dysfunction (creatinine clearance, 52 ml/min), a moderate range of urinary protein (1.51 g/day), and increased serum lysozymes (20.7 microg/ml; normal range, 3.4-8.6 microg/ml). Serum calcium level was within the normal range. Renal biopsy revealed immune complex glomerulonephritis (IgM deposition type) with a membranoproliferative pattern, without granuloma or calcium deposition. Corticosteroid (initial dose of prednisolone [PSL], 1 mg/kg per day) was administered, but neither renal function nor urinary protein improved. She then became nephrotic and her renal function gradually deteriorated. To our knowledge, among uncommon glomerulonephritides with sarcoidosis, five cases of immune complex glomerulonephritis with IgM deposition have been reported. Immune complex glomerulonephritis with IgM deposition is unusual and could be related to sarcoidosis; it may be a characteristic pathology which could provide a clue to elucidate the pathogenesis of sarcoidosis.

Female↗

Expression of Smad1 is directly associated with mesangial matrix expansion in rat diabetic nephropathy.

Diabetic nephropathy is the leading cause of end-stage renal disease, and glomerular mesangial matrix expansion is the hallmark in diabetic nephropathy. However, the precise mechanism for the development of mesangial matrix expansion has remained unknown. The key component involved in mesangial matrix expansion is type IV collagen (Col4). Recently, we have reported that Smad1 transcriptionally regulates expression of Col4 under diabetic conditions in vitro. Here we show that this direct regulator of Col4 also plays a crucial role for mesangial matrix expansion in vivo. Streptozotocin-induced diabetic rats are the model of incipient diabetic nephropathy, and showed various levels of mesangial matrix expansion at 24 weeks. The glomerular expression of Smad1 was significantly increased in diabetic rats with more mesangial matrix expansion by Western blot and immunohistochemical analysis. Furthermore, the glomerular expression of Smad1 was closely correlated with the glomerular expression of Col4 and smooth muscle alpha actin (alpha-SMA), while albuminuria or glomerular filtration rate was not correlated with mesangial matrix expansion. We also found that urinary excretion of Smad1 was closely associated with the severity of mesangial matrix expansion. In cultured mesangial cells expression of Smad1 upregulated the transcriptional activity of key molecules in mesangial matrix expansion, such as Col4 and alpha-SMA. These data indicate the critical involvement of Smad1 in mesangial matrix expansion in the early phase of diabetic nephropathy. Our data imply that urinary Smad1 might be a representative diagnostic marker for mesangial matrix expansion in diabetic nephropathy.

Actins↗

The role of apheresis therapy for ABO incompatible living donor liver transplantation: the Kyoto University experience.

Liver transplantation is a radical surgical therapy for end-stage liver disease. Although in Japan organ transplantation from brain-dead donors (BDD) has been allowed since October 1997, to date, only 29 liver grafts from BDD have been obtained. Thus, most of the liver transplantations carried out use living-donor liver transplantation (LDLT), and BDD liver transplantation is only used in rare cases. In order to carry out LDLT more safely, apheresis (plasmapheresis: PE) plays a major role in our country because of the prevalence of LDLT wherein later re-transplantation is difficult. Thus, because of a limited donor supply and because the needs of patients with end-stage liver disease is critical, use of grafts from ABO-incompatible (ABO-I) donors might be the only available option. From June 1990 to November 2005, 1100 patients underwent 1151 LDLT cases at Kyoto University Hospital. Additionally, 159 LDLT cases (13.8%) received ABO-I living-donor liver grafts. The role of apheresis in ABO-I LDLT is the reduction of antibody titers such as anti-A or anti-B antibody. We carry out preoperative PE as a general rule for ABO-I cases, and the recipient's antibody level against the donor's blood type is decreased to one eighth of the baseline value before LDLT. Until now, baseline immunosuppressive agents included steroids, tacrolimus and cyclophosphamide. At first, splenectomy was carried out during surgery to suppress antibody production, and intraportal (PV) infusion therapy was carried out to control local disseminated intravascular coagulation (DIC) occurring in ABO-I grafts. At that time, three drugs-methylprednisolone, prostaglandin E1 (PGE1), and gabexate mesylate (FOY) were infused continuously for 3 weeks after LDLT. At present, instead of PV infusion therapy, hepatic artery infusion therapy without splenectomy is adopted because of portal thrombosis, and two drugs- methylprednisolone and PGE1- are infused continuously for 3 weeks following LDLT. Recently, we introduced anti-CD20 monoclonal antibody (Rituximab) instead of splenectomy for B cell deletion before ABO-I LDLT. In the present article, we describe the role of apheresis around ABO-I LDLT based on our recent experiences.

ABO Blood-Group System↗

Uterine sensitization-associated gene-1 (USAG-1), a novel BMP antagonist expressed in the kidney, accelerates tubular injury.

Dialysis dependency is one of the leading causes of morbidity and mortality in the world, and once end-stage renal disease develops, it cannot be reversed by currently available therapy. Although administration of large doses of bone morphogenetic protein-7 (BMP-7) has been shown to repair established renal injury and improve renal function, the pathophysiological role of endogenous BMP-7 and regulatory mechanism of its activities remain elusive. Here we show that the product of uterine sensitization-associated gene-1 (USAG1), a novel BMP antagonist abundantly expressed in the kidney, is the central negative regulator of BMP function in the kidney and that mice lacking USAG-1 (USAG1 mice) are resistant to renal injury. USAG1 mice exhibited prolonged survival and preserved renal function in acute and chronic renal injury models. Renal BMP signaling, assessed by phosphorylation of Smad proteins, was significantly enhanced in USAG1 mice with renal injury, indicating that the preservation of renal function is attributable to enhancement of endogenous BMP signaling. Furthermore, the administration of neutralizing antibody against BMP-7 abolished renoprotection in USAG1 mice, indicating that USAG-1 plays a critical role in the modulation of renoprotective action of BMP and that inhibition of USAG-1 is a promising means of development of novel treatment for renal diseases.

Adaptor Proteins, Signal Transducing↗

Pharmacokinetic significance of renal OAT3 (SLC22A8) for anionic drug elimination in patients with mesangial proliferative glomerulonephritis.

PURPOSE: Our previous studies showed that the mRNA level of human organic anion transporter (hOAT) 3 in the kidney was correlated with the rate of elimination of an anionic antibiotic cefazolin. However, the correlation coefficient was not so high. In the present study, therefore, we enrolled more patients to examine whether additional factors were responsible for the correlation. METHODS: hOAT mRNA levels in renal biopsy specimens were quantified using the real-time polymerase chain reaction method. The elimination rates for the free fraction of cefazolin were determined in patients with various renal diseases. RESULTS: In the present study, the coefficient of correlation between the hOAT3 mRNA level and the elimination rates for the free fraction of cefazolin was not so high in the patients overall as in our previous study (r = 0.536). However, following the classification of renal diseases, a better correlation was obtained in patients with mesangial proliferative glomerulonephritis (r = 0.723). In contrast, multiple regression analyses including gender, age, and liver function did not result in any improvements in the correlation coefficients. CONCLUSIONS: These results suggest that the hOAT3 mRNA level is a significant marker of pharmacokinetics with which to predict the rate of elimination of cefazolin in patients with mesangial proliferative glomerulonephritis.

Adolescent↗

Clinical efficacy of intravenous immunoglobulin for patients with MPO-ANCA-associated rapidly progressive glomerulonephritis.

BACKGROUND: To determine whether intravenous immunoglobulin (IVIg) can control disease activity in patients with myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-associated rapidly progressive glomerulonephritis (RPGN). METHODS: Twelve patients with serologically and histologically confirmed MPO-ANCA-associated RPGN (7 men, 5 women; mean age 71 +/- 3 years) received IVIg (400 mg/kg/day) alone for 5 days. The effects of IVIg were evaluated by white blood cell counts, serum C-reactive protein levels, Birmingham Vasculitis Activity Score, rate of change in reciprocal creatinine (1/Cre), and plasma tumor necrosis factor-alpha levels after IVIg administration. Corticosteroids with or without cyclophosphamide were commenced after IVIg. RESULTS: After IVIg treatment, a significant decrease was observed in white blood cell count (p < 0.05), C-reactive protein values (p < 0.001), and Birmingham Vasculitis Activity Score (p < 0.001) concomitant with the amelioration of systemic symptoms. The rate of change in 1/Cre significantly improved (p < 0.05). Plasma tumor necrosis factor-alpha levels that were significantly elevated in patients before IVIg compared with normal controls (p < 0.0001), rapidly declined after IVIg with a significant reduction (p < 0.05). Three months post-treatment with IVIg, all patients showed improvement of disease without serious infectious complications. CONCLUSION: IVIg is a potential component of remission induction therapy for patients with MPO-ANCA-associated RPGN.

Aged↗

Restored expression and activity of organic ion transporters rOAT1, rOAT3 and rOCT2 after hyperuricemia in the rat kidney.

We previously reported that in hyperuricemic rats, renal impairment occurred and organic ion transport activity decreased, accompanied with a specific decrease in the expression of rat organic anion transporters, rOAT1 and rOAT3, and organic cation transporter, rOCT2. In the present study, we investigated the reversibility of the organic ion transport activity and expression of organic ion transporters (slc22a) during recovery from hyperuricemia. Hyperuricemia was induced by the administration of a chow containing uric acid and oxonic acid, an inhibitor of uric acid metabolism. Four days after discontinuance of the chow, the plasma uric acid concentration returned to the normal level, and renal functions such as creatinine clearance and BUN levels were restored, although the recovery of tubulointerstitial injury was varied in sites of the kidney. Basolateral uptake of p-aminohippurate (PAH) and tetraethylammonium (TEA), and both protein and mRNA levels of rOAT1, rOAT3 and rOCT2 in the kidney gradually improved during 14 days of recovery from hyperuricemia. Basolateral PAH transport showed a higher correlation with the protein level of rOAT1 (r(2)=0.80) than rOAT3 (r(2)=0.34), whereas basolateral TEA transport showed a strong correlation with rOCT2 protein (r(2)=0.91). The plasma testosterone concentration, which is a dominant factor in the regulation of rOCT2, was gradually restored during the recovery from hyperuricemia, but the correlation between the plasma testosterone level and rOCT2 protein expression in the kidney was not significant. These results suggest that the regulation of organic ion transporters, rOAT1, rOAT3 and rOCT2, by hyperuricemia is reversible, and the organic ion transport activity restores according to the expression levels of these transporters.

Animals↗

The Na+-excreting efficacy of indapamide in combination with furosemide in massive edema.

BACKGROUND: Massive systemic edema is often observed in patients with severe nephrotic syndrome, including diabetic nephropathy. Although furosemide, a loop diuretic, is often administered to these patients, some patients do not respond to this treatment, still showing massive edema. METHODS: The efficacy of indapamide which has a thiazide-like effect on distal convoluted tubules in combination with furosemide, was evaluated in eight patients with massive edema, in regard to both Na+ excretion and diuresis. Indapamide 2 mg was administered once a day, in the morning, to patients in whom it was considered that furosemide treatment of 40-120 mg a day for 1 week was ineffective. RESULTS: Urinary Na+ excretion was markedly increased, from 83.7 +/- 82.2 mEq/day to 140.7 +/- 33.8 mEq/day after 1 week of the combination therapy compared with furosemide alone (P < 0.01); urine volume was also increased, from 1070 +/- 230 ml to 1359 +/- 296 ml after 1 week of the combination therapy (P < 0.05). In this context, body weight was significantly decreased, from 57.2 +/- 12.3 kg to 53.4 +/- 12.8 kg, after the combination therapy (P = 0.01). Indapamide in combination with furosemide was well tolerated, and no significant changes in serum levels of creatinine and potassium were observed. CONCLUSIONS: This combination therapy appears to be effective in patients with massive edema, as it increased diuresis, and achieved potent Na+ excretion.

Adult↗

Establishment of a diabetic mouse model with progressive diabetic nephropathy.

Although diabetic animal models exist, no single animal model develops renal changes identical to those seen in humans. Here we show that transgenic mice that overexpress inducible cAMP early repressor (ICER Igamma) in pancreatic beta cells are a good model to study the pathogenesis of diabetic nephropathy. Although ICER Igamma transgenic mice exhibit extremely high blood glucose levels throughout their lives, they survive long enough to develop diabetic nephropathy. Using this model we followed the progress of diabetic renal changes compared to those seen in humans. By 8 weeks of age, the glomerular filtration rate (GFR) was already increased, and glomerular hypertrophy was prominent. At 20 weeks, GFR reached its peak, and urine albumin excretion rate was elevated. Finally, at 40 weeks, diffuse glomerular sclerotic lesions were prominently accompanied by increased expression of collagen type IV and laminin and reduced expression of matrix metalloproteinase-2. Nodular lesions were absent, but glomerular basement membrane thickening was prominent. At this point, GFR declined and urinary albumin excretion rate increased, causing a nephrotic state with lower serum albumin and higher serum total cholesterol. Thus, similar to human diabetic nephropathy, ICER Igamma transgenic mice exhibit a stable and progressive phenotype of diabetic kidney disease due solely to chronic hyperglycemia without other modulating factors.

Albumins↗

Gas6 induces Akt/mTOR-mediated mesangial hypertrophy in diabetic nephropathy.

BACKGROUND: We have already reported Gas6 is involved in glomerular hypertrophy observed in diabetic nephropathy. However, the molecular mechanisms involved in glomerular hypertrophy are still unknown, especially in vivo. METHODS: In vivo, diabetes was induced in rats and mice by streptozotocin (STZ) and the activation of the Akt/mTOR pathway in glomeruli was examined. In vitro, mesangial hypertrophy was assessed by [(3)H]leucine incorporation and measuring cell areas. RESULTS: Akt, p70 S6 kinase, and 4E-BP-1 were induced and phosphorylated in rat glomerular lysates after 12 weeks of STZ injection when mesangial and glomerular hypertrophy was observed. We then examined the role of Gas6 by treating STZ-rats with warfarin, and found that warfarin treatment inhibited the phosphorylation of these molecules as well as the hypertrophy. We next examined whether high glucose stimulation can induce the expression of Gas6/Axl in mesangial cells. Stimulation of the cells with 25 mmol/L of glucose increased the expression of Gas6/Axl and mesangial cell size compared with that with 5.6 mmol/L of glucose. This hypertrophic effect was abolished in mesangial cells derived from Gas6 knockout mice. We also found that LY294002 and rapamycin blocked Gas6-induced activation of the Akt/mTOR pathway and mesangial hypertrophy. Furthermore, less phosphorylated Akt-positive or 4E-BP-1-positive areas were found in STZ-treated Gas6 knockout mice than in STZ-treated wild-type mice. CONCLUSION: Our study indicates that the Akt/mTOR pathway is a key signaling cascade in Gas6-mediated mesangial and glomerular hypertrophy and revealed a crucial role of Gas6/Axl and the Akt/mTOR pathway in the development of diabetic nephropathy.

Adaptor Proteins, Signal Transducing↗

Therapeutic strategy and the role of apheresis therapy for ABO incompatible living donor liver transplantation.

Although in Japan, transplant organs obtained from brain-dead donors (BDD) has been allowed since October 1997, to date only 27 liver grafts from BDD have been obtained. The severe shortage of transplantable organs is a big problem, not only in liver transplantation but also other organ transplants. Liver transplantation is a fundamental treatment for end-stage liver disease. In order to perform living-donor liver transplantation (LDLT) in a safer manner, apheresis (plasmapheresis) plays a major role in Japan because of the prevalence of LDLT wherein later re-transplantation is difficult. Therefore, because of a limited donor supply and because the need of patients with end-stage liver disease is critical, use of grafts from ABO-incompatible donors may be the only available option. From June 1990 to November 2004, 1010 patients underwent 1060 LDLT cases at Kyoto University Hospital. Of these, 139 LDLT cases (13.1%) received ABO-incompatible living-donor liver grafts. The role of apheresis in ABO-incompatible LDLT is the reduction of antibody titers such as anti-A or anti-B antibody. We perform preoperative apheresis as a general rule for incompatible cases, and the recipient's antibody level against the donor's blood type is decreased to one eighth of the baseline value before LDLT. Up to the present, baseline antirejection regimens included steroids, tacrolimus and cyclophosphamide. At first, splenectomy was performed during operation to suppress antibody production, and intraportal infusion therapy was performed to control local disseminated intravascular coagulation (DIC) occurring in ABO-incompatible grafts. At that time, three agents--methylprednisolone, prostaglandin E1, and gabexate mesilate--were infused continuously for 3 weeks after LDLT. At present, instead of intraportal infusion therapy, hepatic artery infusion therapy without splenectomy is adopted because of portal thrombosis, and two agents--methylprednisolone and prostaglandin E1--are infused continuously for 3 weeks after LDLT. Recently, we introduced an anti-CD20 monoclonal antibody (Rituximab) instead of splenectomy for B cell deletion before ABO-incompatible LDLT. In this article, we describe our therapeutic strategy and the role of apheresis around ABO-incompatible LDLT.

ABO Blood-Group System↗

Expression levels of renal organic anion transporters (OATs) and their correlation with anionic drug excretion in patients with renal diseases.

PURPOSE: Because the urinary excretion of drugs is often decreased in renal diseases, dosage regimens are adjusted to avoid adverse drug reactions. The aim of present study was to clarify the alteration in the levels of renal drug transporters and their correlation with the urinary drug excretion in renal diseases patients. METHODS: We quantified the mRNA levels of human organic anion transporters (hOATs) by real-time polymerase chain reaction and examined the excretion of the anionic drug, cefazolin, in renal disease patients. Moreover, transport of cefazolin by hOAT1 and hOAT3 were examined using HEK293 transfectants. RESULTS: Among four hOATs, the level of hOAT1 mRNA was significantly lower in the kidney of patients with renal diseases than in the normal controls. The elimination constant of cefazolin showed a significant correlation with the values of phenolsulfonphthalein test and mRNA levels of hOAT3. The uptake study using HEK293 transfectants revealed that cefazolin and phenolsulfonphthalein were transported by hOAT3. CONCLUSIONS: These results suggest that hOAT3 plays an important role for anionic drug secretion in patients with renal diseases and that the expression levels of drug transporters may be related to the alteration of renal drug secretion.

Adult↗

The role of apheresis therapy in living donor liver transplantation.

Liver transplantation is a radical therapy for end-stage liver disease. The severe shortage of transplantable organs is, however, a big problem, not only in liver transplantation but also other organ transplants. Although in Japan, transplantation of organs obtained from brain-dead donors (BDD) has been allowed since October 1997, to date only 27 BDD have been obtained. It has become difficult to procure liver grafts from BDD, therefore we must use liver grafts from living donors. The living-donor liver transplantation (LDLT) program started in 1990 in Japan, and is still the major form of liver transplantation because of the scarcity of cadaveric donors. In the Department of Transplant Surgery, Kyoto Hospital (Kyoto, Japan), the accumulated number of LDLT cases exceeded 955 up to October 2003. In order to perform LDLT under safer conditions, apheresis plays a major role in Japan due to the prevalence of LDLT where later retransplantation is difficult. Clinical indications of apheresis for LDLT are mainly use as a bridge before transplantation, and liver support after transplantation. We describe the effect of apheresis therapy for LDLT patients with nephritic and hepatic problems.

Blood Component Removal↗

Decreased activity of basolateral organic ion transports in hyperuricemic rat kidney: roles of organic ion transporters, rOAT1, rOAT3 and rOCT2.

We investigated organic anion and cation transport activity and the expression of several organic ion transporters in hyperuricemic rat kidney. Feeding oxonic acid, an inhibitor of uric acid metabolism, and uric acid for 10 days significantly increased plasma uric acid level. Plasma creatinine and blood urea nitrogen concentrations also increased in hyperuricemic rats, indicating impaired renal function. The accumulation of organic anions, p-aminohippurate (PAH) and methotrexate, and cations, tetraethylammonium (TEA) and cimetidine, into renal slices was markedly decreased, suggesting decreased transport activity for organic anions and cations at the basolateral membrane in the kidney. The expression levels of basolateral organic anion transporters rOAT1 and rOAT3, and organic cation transporter, rOCT2, significantly decreased in hyperuricemic rat kidney as assessed by mRNA and protein levels. In contrast, the expression of rOCT1 was unaltered by hyperuricemia at both mRNA and protein levels. Moreover, the mRNA expression of kidney-specific organic anion transporters, OAT-K1 and OAT-K2, and organic anion transporting polypeptide (oatp) 1, which localize at the brush-border membrane in the kidney, was unchanged in hyperuricemic rats. In conclusion, we showed decreased basolateral organic anion and cation transport activity, accompanied by a specific decrease in rOAT1, rOAT3 and rOCT2 expression in hyperuricemic rat kidney. These phenomena partly contribute to the changed renal disposition of organic anions and cations in hyperuricemia.

Animals↗