Hepatitis C virus-related kidney disease: various histological patterns.

BACKGROUND: Although hepatitis C virus (HCV) infection is known to be associated with Type 2 cryoglobulinemic glomerulopathy (CG), only a few reports about other types of nephropathy have been published. METHODS: 68 HCV antibody positive patients in whom renal biopsy had been performed for persistent proteinuria, hematuria, and/or renal dysfunction between 1992 and 2008 at our institute were included. The histological, clinical and laboratory characteristics including the age, gender, hypertension, diabetes mellitus, liver histology (chronic hepatitis or liver cirrhosis), HCV-RNA, HCV genotype, splenomegaly, gastroesophageal varices, serum creatinine, hemoglobin, platelet count, rheumatoid factor, cryoglobulin, IgG, IgA, IgM, CH50, C3, C4, creatinine clearance, 24-h protein excretion, and hematuria, between their nephropathy with and without immune deposition were compared. RESULTS: Nephropathy was classified into two groups based on the detection of immune deposits by immunofluorescence microscopy: i.e., a positive group (n = 39) and a negative group (n = 29). The former group was further classified into three types of nephropathy: IgG dominant group (n = 10) (including membranous nephropathy (MN)), IgA dominant group (n = 20) (including IgA nephropathy (IgAN)), membranoproliferative glomerulonephritis (MPGN) (IgA type)), and IgM dominant group (n = 9) (MPGN apart from the IgA type). The latter group included diabetic nephropathy (n = 13), focal glomerular sclerosis (n = 4), and benign nephrosclerosis (n = 3), malignant nephrosclerosis (n = 1), tubulointerstitial nephritis (TIN) (n = 2), minimal change nephrotic syndrome (n = 1), cast nephropathy (n = 1), granulomatous TIN (n = 1), and others (n = 3). An increased serum IgM level, hypocomplementemia, splenomegaly, thrombocytopenia, liver cirrhosis, hematuria, and a high HCV RNA level were features of patients with MPGN of IgM dominant group (consistent with "CG"). CONCLUSIONS: Our results showed various histological patterns of HCV-related kidney disease and the specificity of CG, and revealed that a minority of HCV patients (n = 7) presented typical CG, while IgAN, MN, and diabetic nephropathy were more frequent.

The long-term survival rate of catecholamine-resistant septic shock in Japanese patients who received vasopressin therapy.

BACKGROUND: Septic shock is associated with vasopressin deficiency and hypersensitivity to its exogenous administration. The aim of this study is to review the 28-day survival rate, hemodynamic and renal effects of vasopressin therapy in refractory septic shock Japanese patients. METHODS: 55 Japanese patients experiencing catecholamine-resistant septic shock were treated with vasopressin. Hemodynamic alterations and the serum concentrations of aspartate aminotransferase, total bilirubin and creatinine clearance were evaluated following vasopressin treatment. RESULTS: In both, survivors and non-surviving patients, treatment with vasopressin resulted in a significantly increase in mean arterial pressure, hourly urine output, and a significant decrease in heart rate and total pressor dosage requirements. Creatinine clearance was significantly increased only in survivors. There were no significant changes in the serum concentrations of aspartate aminotransferase and total bilirubin. The 28-day survival rate was 45% (25 patients). CONCLUSIONS: In Japanese septic shock patients, vasopressin infusion improved hemodynamic status and reduced catecholamine requirement, and 28-day survival rate was 45%.

A patient with pregnancy-related acute abdomen after hemodialysis for over 18 years.

Because pregnancy is rare in women with end-stage renal disease, dialysis patients have not been reported to present with acute abdominal symptoms related to pregnancy including ectopic pregnancy. A 41-year-old woman treated with hemodialysis for over 18 years was brought to the emergency room at our institution because of acute abdominal pain. Ultrasonography detected an abdominal fluid collection, and her anemia had worsened (hematocrit 18%). Emergency laparoscopic exploration disclosed a hemorrhagic corpus luteum of pregnancy, causing ovarian bleeding on the left. Coagulation of bleeding points was carried out. At this time, pregnancy at 7 weeks of gestation was discovered. After the procedures, hemodialysis frequency was increased to 5 times weekly, and an erythropoietin derivative was administered to maintain a hematocrit above 30%. The patient developed no hypertension. At 33 weeks of gestation, cesarean section was performed because of a decrease in amniotic fluid and frequent late deceleration of the fetal heart rate. A live baby girl weighing 1,422 g was born. The successful pregnancy reflects remarkable progress in dialysis technology. Pregnancy, then, can underlie an acute abdomen in childbearing-age women (14 - 44 years old) undergoing long-term dialysis.

Angiotensin-independent mechanism for aldosterone synthesis during chronic extracellular fluid volume depletion.

Wild-type (Agt+/+) and homozygous angiotensinogen deletion mutant (Agt-/-) littermates were placed on normal (NS) or low Na diet (LS) for 2 weeks. Plasma aldosterone levels (P(aldo)) were comparable during NS, and similarly elevated during LS in Agt+/+ and Agt-/-. Moreover, in both, the elevation in P(aldo) was accompanied by marked increase in adrenal zona glomerulosa cells and adrenal P450aldo mRNA. Agt-/- mice were distinguished from Agt+/+ mice by their higher plasma K level, by approximately 1.5 and approximately 3.8 mEq/liter during NS and LS, respectively. Within the Agt-/- group, P(aldo) was directly proportional to plasma K. The importance of K for the hyperaldosteronism during dietary Na restriction was verified by the observation that superimposition of K restriction led to hypotension in Agt+/+ and uniform death in Agt-/- mice along with a reduction in P(aldo) by 75 and 90%, respectively. Thus, suppression of potassium, but not angiotensin, led to a marked attenuation of hyperaldosteronism during dietary Na restriction. Therefore, (a) a powerful angiotensin-independent mechanism exists for the hyperaldosteronism during LS; (b) high K is a central component of this mechanism; (c) contrary to current belief, the tonic effect of high K on aldosterone synthesis and release does not require an intact renin-angiotensin system; and (d) normally, intermediary feedback signals for hyperaldosteronism, i.e., both hypotension and high K, are effectively masked by aldosterone actions.

Multicentric Castleman disease with secondary AA renal amyloidosis, nephrotic syndrome and chronic renal failure, remission after high-dose melphalan and autologous stem cell transplantation.

Multicentric Castleman disease is a systemic lymphoproliferative disease with incomplete understood etiology. The various renal complications of this disease may include minimal change disease, mesangial proliferative glomerulonephritis, membranous glomerulonephritis and nephrotic syndrome, caused by secondary amyloidosis. In several reported cases of localized Castleman disease associated with renal amyloidosis and nephrotic syndrome, resection of organs involved by lymphoid proliferation resulted in complete remission. However, therapy of multicentric Castleman disease with renal amyloidosis is not well-established. We treated a case of a 39-year-old woman with multicentric Castleman disease complicated by nephrotic syndrome caused by secondary AA amyloidosis. The patient underwent autologous peripheral blood stem cell transplantation (auto-PBSCT), achieving complete remission. Autologous stem cell transplantation may be an attractive choice in therapy for refractory multicentric Castleman disease.

A pediatric occurrence of crescentic glomerulonephritis associated with antineutrophil cytoplasmic antibodies and mesangial IgA deposits.

Antineutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis usually shows histopathologic features of pauciimmune crescentic glomerulonephritis and occurs late in life. We report a 14-year-old Japanese girl presenting with proteinuria, hematuria and mildly elevated serum creatinine. A renal biopsy specimen demonstrated crescentic glomerulonephritis, immunofluorescence showed mesangial IgA staining. Electron microscopic examination disclosed paramesangial deposits. Serum ANCA against myeloperoxidase (MPO) were detected at high titers. Myeloperoxidase-ANCA-related nephritis accompanied by IgA nephropathy is considered rare in childhood and teen years. Yet, if ANCA assays and detailed electron microscopic examination of renal specimens were performed routinely in patients with rapidly progressive glomerulonephritis, the diagnosis might be more frequent in young patients.

Splenectomy may improve the glomerulopathy of type II mixed cryoglobulinemia.

Many patients with type II mixed cryoglobulinemia have been shown to be infected with hapatitis C virus (HCV). Therefore, interferon-alfa has become the first choice of treatment for patients with HCV-associated cryoglobulinemia. However, the disease often relapses after the discontinuation of interferon therapy. The long-term effect of interferon therapy is controversial. Therefore, a more effective therapy needs to be developed. A 62-year-old Japanese woman was admitted to our hospital for the examination of abnormal liver function tests, severe edema, and purpura in her lower extremities. Glomerulopathy secondary to HCV-related cryoglobulinemia was suspected. Her serum creatinine was increased to 2.1 mg/dL. Interferon therapy was considered initially. However, because of pancytopenia caused by liver cirrhosis and splenomegaly, splenectomy was performed in February 1997, before the start of interferon therapy. Renal biopsy specimen taken at the time of the splenectomy showed typical cryoglobulinemic glomerulonephritis. Gradually, after surgery, the patient's thrombocytopenia and anemia improved, her proteinuria and hematuria were decreased, her cryocrit dropped from 15% to 5%, the Ccr increased from 21.1 mL/min to 48.8 mL/min, and the purpura in her lower extremities disappeared. A repeat renal biopsy performed in May 1998 showed marked histological improvement. Splenectomy is not widely accepted as a treatment for cryoglobulinemia. Our case suggests the possibility that the monoclonal-IgM component of the type II cryoglobulin may be formed in the spleen. In conclusion, splenectomy may be an effective therapy for cryoglobulinemia in patients with HCV-positive liver cirrhosis and pancytopenia secondary to splenomegaly.

Severe ectopic calcification of the intestinal wall in a patient on long-term continuous ambulatory peritoneal dialysis therapy.

We report autopsy findings of a 69-year-old man on long-term CAPD therapy for 13 years who showed linear peritoneal calcification. Continuous ambulatory peritoneal dialysis (CAPD) was started in 1982. He has been administered excessive amounts of vitamin D(3) derivatives (VitD) (2.0 to 2.5 microg daily) and calcium carbonate (4 g daily) for secondary hyperparathyroidism since initiation of CAPD. In May 1995, his intact parathyroid hormone (PTH) level increased over 1,000 pg/mL. Immediately after VitD was changed from pill to liquid, the dose was increased to 5 microg daily. Although the serum calcium level remained between 4.5 and 4.9 mEq/L, and serum phosphate level was 5.0 to 7.2 mg/dL, plain abdominal radiography and computed tomography showed continuous calcification along the intestinal wall in October 1995. In spite of the continuation of CAPD therapy, he remained asymptomatic until he died of congestive heart failure in January 1997. He experienced eight episodes of peritonitis during his clinical course. Autopsy showed that numerous calcified plaques were present on the submucosal portion between the thickened serosa and the longitudinal layer of the muscularis externa. The remainder of the subserosa was fibrotic, and the small arteries had markedly thickened intima and severely narrowed lumina.

Comparison of the penetration ability of human spermatozoa into bovine cervical mucus and zona-free hamster eggs.

In vitro bovine cervical mucus (BCM) penetration tests, sperm penetration assays (SPA) using zona-free hamster eggs, and routine semen analyses were performed on a total of 136 freshly collected semen samples from men who were seen at an infertility clinic. The correlations between bovine cervical mucus penetration and other semen parameters were the percent motile spermatozoa (r = 0.48), progressive motility grade (r = 0.44), sperm count (X 10(6)/ml) (r = 0.47), the percent normal morphology (r = 0.32) and the percent eggs penetrated (r = 0.46) (P less than 0.0001 for each correlation coefficient). When known fertile (n = 32) and infertile (n = 18) groups were tested, positive mucus penetration was associated 75% correctly and positive egg penetration was associated 90% correctly to clinical status. The mucus test had no false-negative results and the SPA had no false-positive results in these groups. It appears, then, that the mucus test and sperm penetration assay, although contributing different elements of data to an infertility evaluation, are both useful adjuncts to a semen analysis.

LDL adsorption improves the response of focal glomerulosclerosis to corticosteroid therapy.

We investigated the therapeutic effect of low density lipoprotein adsorption (LDL-A) in 14 patients who had focal glomerulosclerosis (FGS) with the nephrotic syndrome resistant to steroids. Patients received a total of 6 sessions (2 times a week for 3 weeks). The levels of total cholesterol, triglycerides and low-density lipoprotein were decreased significantly after treatment (by approximately 50%) in all patients (p<0.01). There also seemed to be a possibility that LDL-A improved the response to steroid therapy. The glomerular filtration rate (GFR) increased from 54.4 +/-27.4 ml/min to 70.0+/-30.2 ml/min (p <0.05) and daily urinary protein excretion (Up/day) decreased from 7.24+/-3.58 g/day to 2.56 + 2.00 g/day (p<0.01). Up/day was significantly higher in patients who showed more than 30% improvement of GFR (n = 6) than in patients who showed less than 30% improvement of GFR (n = 7) (9.50+/-3.41 g/day vs 4.59+/-1.17 g/day, p<0.05). The decrease of urinary protein excretion was more marked in younger patients (29.4+/-11.9 vs 49.7+/-14.8, p <0.05). Only electron microscopy was able to detect histological recovery in the patients who showed a decrease of proteinuria after LDL-A therapy and light microscopy was not able to verify or accurately identify the histological response. In conclusion, LDL-A seems to be effective for FGS associated with nephrotic syndrome resistant to steroids, especially in younger patients. Histological assessment of the effect of this treatment requires electron microscopic examination.

Hypererythropoietinemia and hyperreninemia in a continuous ambulatory peritoneal dialysis patient with chronic severe hypotension.

We experienced a patient on continuous ambulatory peritoneal dialysis (CAPD) who showed hypererythropoietinemia (Epo concentration: 86.7 mU/ml, normal range: 8-36 mU/ml), erythrocytosis, high renin concentration (26.5 pg/ml) and chronic hypotension. In this patient the erythrocytosis progressed along with exacerbation of the chronic severe hypotensive state. This patient had systemic circulatory insufficiency as suggested by the fact that he had a fibrous myocardium and an increased anion gap. We hypothesized that circulatory insufficiency due to chronic severe hypotension may lead to the stimulation of the Epo production, due to a decreased oxygen supply to peripheral tissues and/or to the stimulation of the renin angiotensin system even in patients with end-stage renal failure.

A case of mixed connective tissue disease (MCTD) complicated with MPO-ANCA-related necrotizing glomerulonephritis.

Renal diseases of mixed connective tissue disease (MCTD) are not unusual. Although most of them are SLE-like renal impairment with immune complex deposits, systemic sclerosis- (SSc) like renal impairments with intimal thickening of interlobular arteries or arterioles are also encountered. Several cases of SSc complicated with MPO-ANCA-related necrotizing glomerulonephritis (nGN) are reported. Here we report a case which developed MPO-ANCA-related nGN 16 years after the diagnosis of MCTD. She exhibited pauci-immune focal nGN and significantly high titer of MPO-ANCA. She was successfully treated with prednisolone and cyclophosphamide. We believe this is the first case in which MPO-ANCA-related nGN was demonstrated in a patient with MCTD.

Endothelin-1 and endothelin-3 binding to rat nephrons.

The existence of endothelin (ET) receptor subtypes has recently been implicated in the different biological effects of ET in various tissues. Indeed, the cDNAs for two types of ET receptors, ETA and ETB, have been cloned. To further gain insights into ET function in the kidney we examined 125I-labeled ET-1 and ET-3 binding to microdissected rat nephron segments. Specific ET-1 binding was highest in the inner medullary collecting duct, whereas the cortical and outer medullary collecting ducts as well as glomeruli showed moderate binding. There was low, although not significant, ET-1 binding to the early portion of the proximal tubule. Other nephron segments displayed little ET-1 binding. The binding profile of ET-3 along the nephron markedly resembled that of ET-1. Scatchard analyses of binding of ET-1 and ET-3 using cortical collecting ducts revealed a single class of receptor for both ET-1 and ET-3; apparent dissociation constants were 2.05 +/- 0.72 and 2.58 +/- 0.32 nM, and maximal binding capacity values were 0.408 +/- 0.058 and 0.511 +/- 0.047 fmol/mm, respectively. Displacement of 125I-ET-1 binding by unlabeled ET-3 was similar to that produced by unlabeled ET-1. Furthermore, a specific ETB agonist, BQ 3020, almost completely inhibited 125I-ET-1 binding in cortical collecting ducts, whereas a specific ETA antagonist, BQ 123, had little effect. These data indicate that cortical collecting ducts express ETB receptors, to which both ET-1 and ET-3 bind equally.

Hormone receptors and sites of action in the kidney.

Identification of hormone target sites in the nephron has been achieved in part using autoradiography, and largely with microdissection and microanalysis techniques that permit quantitative measurements of hormone binding or postbinding effects in discrete nephron segments. The nephron target sites of hormones whose intracellular second messenger is known have been located by measuring their stimulatory effect on cyclic AMP or GMP production along the nephron. These hormones include arginine vasopressin, parathyroid hormone, calcitonin, and beta-adrenergic catecholamines. In contrast, the action sites of hormones whose cellular mediators are less well understood have been identified using micro modifications of conventional binding techniques scaled down to the minute (less than or equal to 1 microgram protein) amount of tissue available. In this group are aldosterone, corticosterone, insulin, angiotensin II, alpha-adrenergic catecholamines and dopamine. Atrial natriuretic peptides and glucagon have been studied with both methods. The precise localization of hormone receptors and sites of action in the functionally heterogeneous nephron is critical for understanding the interactions between the kidney and the endocrine system in fluid volume homeostasis, blood pressure control, and in biochemical and metabolic regulation.

Early effects of aldosterone on Na-K pump in rat cortical collecting tubules.

Sustained exposure to aldosterone (Aldo) increases the abundance and activity of the Na-K pump in cortical collecting tubules (CCT). However, the onset and mechanism of the early interaction of Aldo with the CCT pump, especially in adrenal-intact animals, are unclear. We evaluated the short-term effects of the hormone on Na-K-adenosinetriphosphatase (ATPase) activity and on ouabain-sensitive 86Rb uptake, a measure of the transporting rate of the pump, in microdissected CCT from adrenal-intact rats. Incubation with Aldo (10(-8) M, 2 h) had no effect on Na-K-ATPase activity (Vmax), whereas it produced at least a twofold increase in 86Rb uptake. This effect was generated by physiological concentrations of the hormone (threshold 10(-10) M; apparent K1/2 approximately 10(-9) M), after a short lag of less than or equal to 30 min. Incubation with Aldo in the presence of amiloride or nystatin or in a Na-free medium (choline chloride) did not prevent the enhanced 86Rb uptake seen after Aldo alone; possible interpretations of these observations are discussed. We conclude that Aldo produces a rapid stimulation of pump function in CCT that precedes its induction of new pump synthesis; the physiological significance of this effect is suggested by its occurrence in tubules from adrenal-intact animals within the time frame and concentration range of the hormone's effects on electrolyte transport.

Endothelin-1 and -3 binding to ETB receptors in rat renal tubules.

To increase understanding of endothelin (ET) function in the kidney, we investigated binding of the radioligand of endothelin isopeptides to microdissected rat nephron segments. Specific ET-1 binding was highest in the inner medullary collecting duct, whereas the cortical and outer medullary collecting ducts showed moderate binding, as did the glomeruli. There was slight ET-1 binding to the early portion of the proximal tubule. Other nephron segments displayed little ET-1 binding. The binding profile of ET-3 along the nephron markedly resembled that of ET-1. Scatchard analyses of ET-1 and ET-3 binding to cortical collecting ducts revealed a single class of receptor for both ET-1 and ET-3. Displacement of [125I]-ET-1 binding by unlabeled ET-3 was similar to that produced by unlabeled ET-1. Moreover, a specific ETB agonist, BQ-3020, almost completely inhibited [125I]-ET-1 binding in cortical collecting ducts, whereas a specific ETA antagonist, BQ-123, had little effect. These data indicate that cortical collecting ducts express ETB receptors, to which both ET-1 and ET-3 bind equally.

Detection of endothelin-1 mRNA by RT-PCR in isolated rat renal tubules.

A combination of reverse transcription and polymerase chain reaction was utilized to detect baseline endothelin-1 (ET-1) mRNA expressed in renal tubules dissected from rats. 5' and 3' primers were constructed according to human ET-1 genomic DNA. Rat ET-1 mRNA was found to be expressed only in cortical through medullary collecting ducts in addition to glomeruli. Sites for tubular synthesis of ET-1 corroborate well with major ET-1 binding sites along the nephron, indicating autocrine/paracrine role of ET-1 in the renal tubules and supporting a prevailing concept on such function of ET-1 in many differing tissues.

Desensitization of endothelin-1 binding by vasopressin via a cAMP-mediated pathway in rat CCD.

In renal collecting ducts, endothelin-1 (ET-1) inhibits Na+ reabsorption and antagonizes the effects of arginine vasopressin (AVP). Whether AVP may affect ET-1 action in the collecting ducts that mainly express the ETB receptor subtype, however, remains unknown. Since ETB, but not ETA, possesses a consensus amino acid sequence for possible phosphorylation by protein kinase A (PKA), we hypothesized that AVP may influence ET-1 binding to the ETB receptor via PKA. In microdissected rat cortical collecting ducts, the specific ET-1 binding decreased by 35% (15.6 +/- 4.4 vs. 24.0 +/- 3.6 amol/mm in control) following 20-min preincubation with 10(-7) M AVP. This decrease in ET-1 binding was mimicked by 10(-5) M forskolin and by 10(-4) M dibutyryl (DB) adenosine 3',5'-cyclic monophosphate (cAMP), indicating that this heterologous desensitization may be caused by a cAMP-dependent mechanism. Moreover, N-(2([3-(4-bromophenyl)-2-propenyl]-amino]-ethyl)-5- isoquinolinesulfonamide (H-89) and the Rp diastereoisomer of cAMP, Rp-cAMPS, which are both PKA-specific inhibitors, eliminated AVP-induced ETB receptor desensitization. The reduction in ET-1 binding was characterized by a decrease in binding affinity [dissociation constant (Kd) = 4 vs. 2 nM in control] with no change in maximal binding capacity. In contrast, forskolin and DBcAMP had no effect on ET-1 binding in endothelium-denuded aortic strips, which mainly express ETA subtype. These results showed that AVP rapidly downregulates the ETB receptor by reducing Kd through a PKA-dependent pathway. Thus ET-1 and AVP may act in a mutually antagonizing manner in the renal collecting ducts.

Dopamine inhibits Na/K-ATPase in single tubules and cultured cells from distal nephron.

Dopamine decreases tubular sodium reabsorption, attributed in part to Na/K-ATPase inhibition in the proximal convoluted tubule (PCT). Because the final regulation of sodium excretion occurs in the collecting duct, where we have demonstrated specific dopamine DA1 binding sites, we examined the effects of dopamine, and of DA1 and DA2 receptor agonists on the Na/K pump in the microdissected rat cortical collecting duct (CCD) and in Madin-Darby canine kidney (MDCK) cells, a line derived from the dog distal nephron. Dopamine inhibited pump activity in CCD by approximately 40%-50%, an effect proportionally larger than in the PCT. Unlike in the latter, the effect of dopamine was reproduced by the DA1 agonist fenoldopam, which inhibited the CCD pump in dose-dependent manner (maximum, 10 microM). The DA2 agonist quinpirole was without effect, either alone or in combination with fenoldopam. These actions on Na/K-ATPase paralleled in reciprocal fashion effects on adenylate cyclase: dopamine or fenoldopam, but not quinpirole, produced a significant increase in cAMP content, and the stimulation by dopamine was blocked by SCH 23390. Inhibitors of cAMP phosphodiesterase (3-isobutyl-1-methyl-xanthine and theophylline), as well as forskolin and dibutyryl-cAMP, mimicked the effect of dopamine on the pump, underscoring the role of increased cAMP in this phenomenon. Both dopamine and fenoldopam inhibited Na/K-ATPase activity in MDCK cells. The results indicate that besides the PCT dopamine inhibits Na/K-ATPase activity in cells of the distal nephron, where its effect on the pump appears to be more pronounced and is mediated by activation of the DA1 receptor. The natriuretic effect of dopamine is probably exerted at both proximal and distal nephron sites.