Myeloma kidney cast nephropathy in a rat model of multiple myeloma

Renal insufficiency occurs in some, but not all, patients with multiple myeloma and Bence Jones proteinuria. Many of these patients are found to have a distinctive renal lesion characterized by distal nephron cast formation. It has been proposed that the specific Bence Jones protein (BJP) which is produced by a myeloma tumor may play an important role in the genesis of this cast nephropathy and that patients excreting BJPs with the highest isoelectric points (pI) are those most likely to develop this cast nephropathy. We have utilized a rat model of multiple myeloma to further evaluate the relationship between Bence Jones proteinuria and the development of myeloma cast nephropathy. This model employed immunoglobulin-secreting tumors obtained from a unique strain of rats in which they spontaneously develop. These tumors were transplanted to a homologous strain of rats and the effect on renal function and morphology in these rats were evaluated. Four different kappa light chain synthesizing tumors were studied. Following transplantation of the tumors, all rats were maintained on a diet designed to produce an acid urine (pH 5.5 to 6.0) and maximal urinary concentration (2000 to 3000 mOsm/kg). Among the rats excreting BJP of pI 6.7, 17 of 18 had virtually normal renal histology. Of the 15 rats with BJP of pI 7.6, 11 also had normal renal histology. However, 12 of 12 rats excreting BJP of pI 5.2 developed a distal nephron, light chain containing cast nephropathy. In the pI 4.3 group, 6 of 12 rats developed acute tubular necrosis, and the remaining six animals sustained a less severe lesion which was characterized by the presence of bland hyaline casts. The mean serum creatinine level obtained at the time of sacrifice was elevated (compared to that found in sham-operated controls) in the pI 5.2 group (P less than 0.001) and the pI 4.3 group (P less than 0.01) but not in the pI 6.7 or 7.6 groups. These results do not support the concept that cationic BJP's are more nephrotoxic than those that carry a more negative charge and indicate that other factors must determine the nephrotoxicity of a given BJP.     

Nephrotoxicity of Bence Jones proteins in the rat: importance of protein isoelectric point

Bence Jones proteins (BJP) were isolated from the urine of 12 patients with multiple myeloma and various degrees of renal dysfunction. Proteins were characterized as to type (six type lambda and five type kappa), isoelectric point (pI), and secondary structure by circular dichroism (CD). Clinical renal function was more impaired with type-lambda proteins and with proteins of pI greater than 5.7. CD studies distinguished kappa from lambda proteins in most cases but did not correlate with nephrotoxicity. Protein dimer preparations were tested for nephrotoxicity in aciduric, hydropenic, female, Sprague Dawley rats by following renal function and morphology over 6 hours after injection i.p. of 300 mg of protein. Twelve rats of urine pH less than 5.5 injected with four BJP of pI less than 5.7 showed a mean rise in SUN of 5.3 mg/dl and in creatinine of 0.06 mg/dl, compared with a mean rise of 28.0 mg/dl (SUN) and 0.75 mg/dl (creatinine) in 21 rats injected with seven BJP of pI greater than 5.7 (P less than 0.01). Seven sodium-bicarbonate-fed rats of urine pH greater than 8 injected with a BJP of pI 6.2 showed mean rise in SUN of 1.8 mg/dl and in creatinine of 0.01 mg/dl, compared with 19.3 mg/dl (SUN) and 0.55 mg/dl (creatinine) in 7 aciduric rats injected with the same BJP (P = 0.009). Morphologic and immunohistologic studies showed distal cast formation in 9 rats with acute deterioration in renal function. It is concluded that BJP of pI greater than urine pH are acutely nephrotoxic in the rat by a mechanism that may involve a charge interaction in the distal nephron.     

Exogenous creatinine clearance accurately assesses filtration failure in rat experimental nephropathies

The purpose of this study was to determine whether creatinine clearance (Ccr), determined under conditions of exogenous creatinine infusion, accurately reflects glomerular filtration rate (GFR) in the rat. Normal rats and rats with either glomerulopathy (nephrotoxic serum nephritis, adriamycin nephropathy), ablative nephropathy, or acute renal failure (ischemic, HgCl2) were subjected to simultaneous Ccr and inulin clearance (Cin) determinations at a time that plasma creatinine concentrations were maintained at 10 to 20 mg/dL by exogenous creatinine infusion. Cin ranged from 0.02 to 2.49 mL/min, and a nearly perfect correlation with Ccr (r = .997) was obtained. Excellent correlations between Ccr and Cin were found in each of the individual study groups. When the rats were subdivided into groups according to their level of renal function (Cin greater than 1.5 mL/min; Cin 0.5 to 1.49 mL/min; Cin 0.02 to 0.49 mL/min), excellent correlations between Cin and Ccr were still observed (r = .93, .97, and .97, respectively). We concluded that exogenous Ccr accurately reflects GFR in the rat over the entire range of renal function and in a wide variety of experimental nephropathies. Given the simple methodology, exogenous Ccr could have substantial research application for assessing degrees of excretory function in experimental renal disease.     

The effect of saline loading on uranium-induced acute renal failure in rats

Studies were performed to examine the effect of saline loading on uranium-induced acute renal failure (ARF) in rats. Forty-eight hours after the i.v. injection of uranyl acetate (UA, 5 mg/kg), inulin clearance rate (Cin) decreased to approximately 43% of the control value in water drinking rats (P less than 0.005). Animals receiving continuous isotonic saline infusion following UA showed higher urine flow and Cin (60% of control, P less than 0.01), and lessened intratubular cast formation when compared with water-drinking ARF rats. A short-term saline infusion following UA did not attenuate the decline in Cin (43% of control). An inverse relationship was found between Cin and the number of casts (r = -0.75, P less than 0.01). Multiple regression analysis showed that standardized partial regression coefficient is statistically significant between Cin and cast formation (-0.69, P less than 0.05), but not between Cin and tubular necrosis (-0.07, P greater than 0.05). Renin depletion caused by DOCA plus saline drinking did not attenuate the decline in Cin in ARF (47% of control). No significant difference was found in urinary uranium excretion between water-drinking and saline-infused ARF rats. The findings suggest that continuous saline infusion following UA attenuates the decline in Cin in ARF rats; and that this beneficial effect of saline loading is associated with lessened cast formation rather than with suppressed renin-angiotensin activity or enhanced urinary-uranium excretion.     

Estimation of glomerular filtration rate by inulin clearance: comparison with creatinine clearance

Inulin clearance (Cin) is widely believed to be the gold standard of the glomerular filtration rate (GFR). However, in Japan, Cin has not been officially recognized by the Ministry of Health, Labour and Welfare of Japan for clinical use. Creatinine clearance (Ccr) has been used to estimate the renal function of patients, but there have been many studies in which Ccr estimates were GFR falsely high because the metabolism and tubular excretion of creatinine widely varied according to the pathophysiological state of the patient. In the present study, we determined Cin and Ccr simultaneously in 116 adult patients with renal diseases and diabetic mellitus. The clearance study was performed by the modified Wesson's method. The inulin preparation was FFI-1010 (Fuji Yakuhin Co. Ltd.). Inulin in serum and urine was determined by the newly devised enzymatic assay (Toyobo Co. Ltd.), which is specific for inulin. The mean Cin was 35.0 +/- 14.4 ml/min/1.73 m2. The mean Ccr(the enzyme assay) was 63.6 +/- 24.1 ml/min/1.73 m2 and that of the kinetic Jaffe assay was 55.3 +/- 19.3 ml/min/1.73 m2. Mean Ccr/Cin was 1.93 +/- 0.73, 1.69 +/- 0.62, respectively. This ratio was significantly different(p < 0.05) in the degree of reduction of Cin, with values of 2.07 +/- 0.82 (Cin < 40 ml/min/1.73 m2) and 1.64 +/- 0.32(40 < Cin < 80 ml/min/1.73 m2), respectively. Only 8 patients were classified into the same degree of reduced renal function (the Guideline of Japanese Society of Nephrology). The findings of this study suggest that the GFR determined by Ccr could misjudge the renal function of patient and delay the administration of proper treatment of the patient. Introduction of Cin into the clinical field is necessary to avoid this delay.     

Effects of desoxycorticosterone acetate (DOCA) plus saline drinking on gentamicin-mediated nephropathy in rats.

Studies were performed to examine the effect of desoxycorticosterone acetate (DOCA) treatment plus isotonic saline drinking on gentamicin (GM)-mediated nephropathy in rats. GM, 40 mg/kg/day, was subcutaneously injected for 13 days following a 5-week treatment with water drinking or DOCA (10 mg/kg/week) plus saline drinking. Twenty-four hours after the last injection of GM, renal blood flow (RBF) and Cin decreased to approximately 69% and 52% of the control values in water-drinking GM-treated rats, respectively, but was well maintained in DOCA plus saline-drinking GM-treated animals. There was no significant difference in morphologic tubular injury or the renal cortical GM content between GM-treated groups. Saline drinking alone (1% saline, 5 weeks) lessened neither GM-induced reduction in GFR nor tubular damage. Body weight loss occurred following GM injection in the water-drinking group but not in the DOCA plus saline-drinking and saline-drinking-alone groups. DOCA plus saline drinking significantly suppressed the plasma renin activity (PRA) but saline drinking alone did not. A significant inverse correlation was found between PRA and Cin in water-drinking GM-treated and untreated rats. The data suggest that the beneficial effect of DOCA plus saline drinking is associated with renin-angiotensin suppression rather than with the renal GM content or well-maintained hydration.     

Current approach to diagnosis and management of acute renal failure in myeloma patients

Renal impairment is a serious complication of multiple myeloma. The primary cause of renal failure in myeloma is damage to the kidney by excessive amounts of light chain produced by the myeloma tumor, giving rise to cast nephropathy (myeloma kidney), although there are several other important precipitants. Significantly poor prognosis is observed in patients who do not recover their renal function; however, with the advent of more effective therapies and a greater understanding of the pathogenesis of the underlying process, it has become possible to reverse renal impairment in greater numbers of patients. Determining whether the renal impairment is due to cast nephropathy should be the first priority, and once the diagnosis is confirmed, appropriate treatment should be initiated without delay. Reduction of serum free light chain is the key to recovery of renal function in these patients. The role of chemotherapy and extracorporeal removal of light chain are discussed.     

Clinical study of tubular creatinine secretion in renal dysfunction]

Endogenous creatinine clearance (Ccr) has been much more commonly used to estimate renal function in clinical medicine, in comparison with inulin clearance (Cin) which is more accurate measure of glomerular filtration rate (GFR). There is, however, increasing difference between Ccr and Cin as renal function deteriorates. Since this difference is considered to be resulting from the tubular secretion of creatinine, Cin and Ccr were simultaneously measured in 81 patients with chronic renal disease, as well as 12 control subjects in this study. As Cin decreased, the Ccr/Cin ratio increased and the ratio varied widely even in patients with similar degree of renal impairment. The subjects were classified into 3 groups, group I (Cin greater than 80 ml/min), group II (80 ml/min greater than or equal to Cin greater than or equal to 40 ml/min) and group III (Cin less than 40 ml/min). The mean values of tubular creatinine secretion (Tcr) were 0.07 +/- 0.173 mg/min (+/- SD) in group I, 0.205 +/- 0.136 mg/min in group II and 0.333 +/- 0.139 mg/min in group III, respectively. Therefore, Tcr in the group of the severe impairment was the highest. In addition, Ccr and Cin were measured in 15 patients with chronic nephritis before and after an intravenous bolus injection of cimetidine (5 mg/kg BW). Following the injection Ccr/Cin ratio was reduced from an initial value of 1.51 +/- 0.23 to 1.18 +/- 0.13 in group II and from 2.00 +/- 0.44 to 1.55 +/- 0.25 in group III, respectively. Tubular secretion of creatinine appeared to be inhibited by cimetidine even in the patients with severe renal dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of angiotensin II antagonism on the regression of kidney disease in the rat

BACKGROUND: Normalization of proteinuria and even regression of glomerulosclerosis seem to occur in progressive renal disease upon blockade of the renin-angiotensin system. Here we quantified the effect of a combination of an angiotensin converting enzyme (ACE) inhibitor and an angiotensin II (Ang II) receptor antagonist on renal function and structure in spontaneous overt nephropathy in male Munich Wistar Fromter (MWF) rats. METHODS: Three groups of MWF rats were used: group 1 was studied at 25 weeks to provide baseline renal function and structure; group 2 was followed until 40 weeks of age; group 3 was treated with lisinopril (40 mg/L) and valsartan (180 mg/L) in drinking water from 25 to 40 weeks. A group of untreated Wistar rats (group 4, 40 weeks) was used as the control. At the end of the study renal hemodynamics, kidney tissue morphology, accumulation of type III collagen and evaluation of interstitial inflammatory cells were performed. RESULTS: MWF rats spontaneously developed hypertension, proteinuria, glomerulosclerosis, interstitial volume expansion and protein cast accumulation. Combined treatment completely reversed protein excretion and ameliorated renal plasma flow and the glomerular ultrafiltration coefficient. The combined therapy was effective in halting progressive glomerulosclerosis, particularly in glomeruli with mild sclerotic lesions, and reduced interstitial volume expansion. Type III collagen accumulation and protein cast also were reversed. Infiltrating cells were massively present in the interstitium already at 25 weeks, and augmented at 40 weeks in untreated rats. Combined treatment reduced infiltrating cells to values comparable to normal controls. CONCLUSIONS: These data indicate that in animals with spontaneous overt nephropathy, Ang II antagonism normalized proteinuria, eliminated inflammatory cell infiltration, and ameliorated glomerular and tubular structural changes.     

Transforming growth factor-beta 1 production is correlated with genetically determined ACE expression in congenic rats: a possible link between ACE genotype and diabetic nephropathy

Genetic background appears to modulate the development of diabetic vascular complications. In particular, polymorphisms in the ACE gene have been associated with diabetic nephropathy and, in some studies, macrovascular complications. However, the links between ACE gene polymorphism and factors implicated in diabetes complications remain unknown. The aim of this study was to determine whether the ACE genotype could modify factors, such as transforming growth factor (TGF)-beta 1, involved in the complications of diabetes. For this purpose, congenic rats (L.BNAce10), differing from the LOU strain in only a small segment of chromosome 10 containing the ACE locus, were generated. These congenic rats have plasma ACE levels twice as high as the donor strain. Diabetes was induced in rats of both strains, and its effects on ACE and TGF-beta 1 expressions were evaluated in lungs and kidneys. In lung, the main source of ACE production, ACE mRNA levels and activity were higher in L.BNAce10 rats than in LOU rats. Diabetes increased ACE lung expression in rats of both strains in a similar manner. TGF-beta 1 expression was also higher in lungs of L.BNAce10 compared with LOU rats and was also increased by diabetes. Furthermore, a strong correlation was found between TGF-beta 1 and ACE expressions. In renal arterioles, ACE and TGF-beta mRNA expressions were higher in L.BNAce10 rats than LOU rats (both diabetic and nondiabetic). In these vessels, there was also a correlation between ACE and TGF-beta 1 expressions. Urine TGF-beta 1 concentration depended on the genotype and was further increased by diabetes. These results show that TGF-beta 1 expression is correlated with ACE expression and suggest that this growth factor could be a link between ACE gene polymorphism and diabetic vascular complications.     

Effect of cyclophosphamide on leukocytic subset distributions in rats carrying the Dunning R3327-MAT-LyLu prostatic adenocarcinoma

The Dunning R3327 adenocarcinoma represents a model for studying prostate cancer in rats; early studies have indicated its utility for studying relationships between tumor growth, immunologic markers, and chemotherapy. Normal animals and those bearing the metastatic Dunning R3327 MAT-LyLu tumor were treated with 10, 30, and 100 mg/kg doses of cyclophosphamide (CTX) and their spleens assayed for leukocytic subset distributions using monoclonal antibodies. Tumor-bearing animals had significant reductions in helper T cell content as well as reduced helper/suppressor T cell ratios, compared to controls. These effects occurred rapidly following implantation and were not reversed by chemotherapy. When administered to both tumor- and non-tumor-bearing animals, CTX also depleted T cell populations. Despite reductions produced in all subsets, two administrations of CTX (30 mg/kg) were capable of retaining (in non-tumor-bearing animals) or restoring (in tumor-bearing) normal helper/suppressor T cell ratios. Such studies aid in identifying therapeutically effective dosages of cytotoxic drugs that minimize their deleterious effects on the immune system.     

Myeloma cast nephropathy: a rare cause of primary renal allograft dysfunction

We describe a rare case of primary renal allograft dysfunction due to myeloma cast nephropathy in a patient with no prior history of multiple myeloma preceding her transplantation. A 72-year-old woman on hemodialysis for 4 years prior to transplantation due to presumed hypertensive nephrosclerosis developed immediate graft dysfunction posttransplantation. The graft biopsy specimens were consistent with myeloma cast nephropathy for which she was treated with plasmapheresis and chemotherapy using bortezomib and dexamethasone. She achieved partial hematologic remission and recovered excellent graft function by 3 months posttransplantation. This is the first report of successful recovery of renal allograft function after development of cast nephropathy.     

雷帕霉素加重蛋白负荷肾病大鼠肾脏的损害及氯沙坦的保护作用

目的 观察雷帕霉素对蛋白负荷肾病大鼠肾脏组织和肾功能的影响及氯沙坦的保护作用，并探讨相关机制。 方法 采用牛血清蛋白（BSA）诱导Wistar雌性大鼠建立蛋白负荷的肾病大鼠模型，根据处理不同分成模型对照组、雷帕霉素组（单纯使用雷帕霉素，Rapa组）和氯沙坦组（同时使用雷帕霉素和氯沙坦）。检测不同时间点各组大鼠的尿蛋白量（24 h）和肾功能水平，并对肾组织进行光镜和电镜检查。 结果 实验第7 天，Rapa组和氯沙坦组大鼠尿蛋白量（24 h）均显著高于模型组（均P < 0.05），但氯沙坦组大鼠尿蛋白量（24 h）较Rapa组有明显缓解（P < 0.05）。实验第14天，Rapa组大鼠尿蛋白量（24 h）仍显著高于模型组（P <0.05），而氯沙坦组与模型对照组间的尿蛋白量（24 h）差异已无统计学意义。肾组织光镜检查显示Rapa组大鼠肾小管管腔中的蛋白管型明显增加；而氯沙坦组的蛋白尿和蛋白管型较Rapa组有明显减少；电镜结果显示Rapa组肾脏可见明显的肾小球局灶性足突融合。 结论 雷帕霉素增加蛋白负荷肾病大鼠的蛋白尿水平，其主要机制可能与雷帕霉素损伤肾小球足细胞后导致肾小球滤过屏障的改变有关；氯沙坦可以减轻雷帕霉素所致的大量蛋白尿。     

Comparative evaluation of urographic contrast media, inulin, and 99mTc-DTPA clearance methods for determination of glomerular filtration rate in clinical transplantation

Plasma clearance of inulin (Cin), 99mTc-DTPA (CDTPA), and urographic contrast media (CCM) were determined simultaneously in 31 patients with varying levels of renal function evaluated in the setting of affiliated cardiac and renal transplantation programs. Cin and CDTPA were calculated from the ratio of simultaneously measured plasma concentration and urine excretion rate of these test agents (UxV/P). CCM was derived from x-ray fluorescence measurement of plasma iodine (PI) content following intravenous injection of 50 ml of nonionic, low-osmolar contrast media (180 mg I/ml). Urine collections were not required for CCM determinations. No adverse reactions attributable to CM occurred in any patient, and follow-up serum-creatinine values did not differ significantly from prestudy levels. CCM determined from the rate of decline in PI between 3 hr and 4 hr following administration of contrast media ("slope-intercept" technique) [Ccm-SI] correlated closely with corresponding levels of Cin (r = .86, P less than 0.0001). and CDTPA (r = 0.89, P less than 0.0001). Mean CCM-SI/Cin and CCM-SI/CDTPA ratios for the entire study cohort were 1.09 +/- 0.06 and 1.08 +/- 0.06, respectively. CCM-SI determinations also correlated well with CCM levels derived from a single measurement of PI ("single sample" technique) made at 3 hr following injection of contrast media (r = 0.94, P less than 0.0001). Both CCM-SI and CCM determined by the "single sample" method (CCM-3 degrees SS) tended to overestimate Cin and CDTPA, however, when the latter were less than 20 ml/min/1.73 m2 (mean CCM-SI/Cin and Ccm-3 degrees SS/Cin ratios 1.36 +/- 0.14 and 1.95 +/- 1.0, respectively. Reproducibility was evaluated by paired comparison of 3-hr vs. 4-hr "single sample" CCM determinations (r = 0.99, P less than 0.0001). In addition, analysis of the variation in iodine content between duplicate specimens obtained at each of these time intervals revealed a mean ratio of 1.0 +/- 0.01 (P = NS vs. identity). Contrast clearance determination utilizing the slope-intercept method is accurate, safe, pragmatic, and more precise than serum-creatinine and endogenous-creatinine clearance for measurement of renal function in clinical transplantation.     

Utility and limitations of serum creatinine as a measure of renal function in experimental renal ischemia-reperfusion injury

BACKGROUND: Ischemia-reperfusion injury (IRI) is the major cause of delayed graft function in renal allografts. The present study was performed to investigate the validity of serum creatinine (SCr) level as an indicator of postischemic renal dysfunction in mice. METHODS: Renal IRI or sham surgery was induced in C57BL/6 mice, and SCr level and inulin clearance (Cin) were measured between 24 hr and 7 days after ischemia. RESULTS: Cin in IRI mice was reduced 75% at 72 hr after ischemia in association with a nearly threefold increase in SCr level. Cin in IRI mice did not recover between 72 hr and 7 days after ischemia, even though SCr level at 7 days was not different between control and IRI mice. In IRI mice, SCr level measured at 24, 48, and 72 hr after ischemia correlated inversely with Cin measured at 72 hr, but not 7 days, after ischemia. CONCLUSIONS: SCr level in the early postischemic period (24-72 hr) seems to be a valid indicator of early postischemic renal dysfunction, and that renal function remains markedly depressed at 7 days despite suggestion from the SCr value that renal function is improving.     

The acute effect of growth hormone on GFR is obliterated in chronic renal failure

Recombinant human growth hormone (rhGH) has become available for treatment of growth failure in uremic children. Since GH raises the glomerular filtration rate (GFR) in healthy individuals, there has been concern that treatment with rhGH, by its action on glomerular hemodynamics, may adversely affect the progression of renal failure. To further address this issue, inulin clearance (enzymatic steady-state infusion technique) was measured in 7 healthy normotensive adult volunteers and 7 patients with chronic renal failure from glomerular or non-glomerular causes. Subjects were given 4.5 U bid of rhGH by s.c. injection for 3 days. In volunteers, a significant increase in Cin was noted 72 h after start of rhGH administration from 120 ml/min/1.73 m2 (range 91-158) to 133 (108-167) (p less than 0.02). In contrast, no significant increase in Cin was noted in patients with chronic renal failure (baseline Cin 21 ml/min/1.73 m2, 15-32; after rhGH 22 ml/min/1.73 m2, 15-32) despite pronounced effects of GH on S-cholesterol and urea excretion rate. The results show that stimulation of GFR by short-term administration of rhGH is obliterated in chronic renal failure.     

A new alloantigen-independent control for chronic allograft nephropathy rat models

BACKGROUND: Isografts are used as controls in many transplant experiments. Our laboratory and others have noticed histological changes in control isograft groups of rats similar to allograft groups, suggesting alloantigen-independent factors contributing to chronic allograft nephropathy. However, the isograft model as a nonalloantigen control is flawed because of the potential of unrecognized minor antigen differences between rats. We designed a study using autografts to isolate alloantigen-independent factors in the rat renal transplant allograft model. MATERIALS AND METHODS: Male Lewis rats weighing 150-250 g underwent a procedure designed to mimic the injury of renal transplant, in which the left kidney was perfused with cold University of Wisconsin solution and subjected to similar cold and warm ischemic times as Lewis isograft rats undergoing renal transplanation. RESULTS: Six autograft rats were compared to five isograft and three single nephrectomy rats. Autograft rats showed normal kidney function according to serum BUN, Cr, and urinary protein. At 360 days, four of six autografts displayed normal renal parenchymal histology, whereas the remaining two autografts displayed histological changes scored as Banff acute rejection 1a and 1b. At sacrifice time, four of five isografts showed histological changes scored as Banff chronic rejection 1 and the single nephrectomy group showed normal histology in the remaining native kidney. CONCLUSIONS: Our data demonstrate that the chronic nephropathy observed in the isograft cannot be completely freed from suspicion of immunological origin. We propose that the autograft model for rat renal transplant research is a better nonimmunologic control than the isograft model for chronic allograft nephropathy.     

Clinical pictures and novel mutations of WT1-associated Denys-Drash syndrome in two Chinese children

Denys-Drash syndrome (DDS) is characterized by early onset of nephropathy, genitalia malformation, and Wilms' tumor, where WT1 is the gene that is mutated in most patients. We report two de novo mutations in WT1 found in two Chinese DDS children. Patient 1 was a boy with complete DDS who was presented with progressive nephropathy, unilateral Wilms' tumor, bilateral cryptorchidism, and renal histology showing diffuse mesangial sclerosis (DMS). When the patient was 24 months old, a liver ultrasound showed multiple nodules, and the patient died of pneumonia 1 month later. The de novo novel mutation, c.1130A>T (p.His377Leu), was identified; the mutation replaces histidine with leucine in the zinc finger (Znf) structure and is predicted to change the local spatial structure of the protein. Patient 2 had 46 XX with incomplete DDS and presented with normal genitalia, proteinuria, unilateral Wilms' tumor with renal pedicle lymph node metastasis, and renal histology showing DMS. Her renal function remains normal after 48 months. A de novo mutation, c.1168C>T (p.Arg390Term), was identified; it truncates 60 amino acids at the C terminus, and it is predicted to result in loss of the DNA-binding capacities of the WT1 protein.     

Estimation of glomerular filtration rate in obese patients with chronic renal impairment based on serum cystatin C levels

BACKGROUND: Serum cystatin C (Scyst) has an obvious advantage in recognizing the initial stages of renal impairment. However, several recent studies suggest that Scyst may also be affected by some nonglomerular factors such as thyroid dysfunction, glucocorticoid administration or metabolic status of the diabetic patient. The aim of this study was to evaluate whether obesity could affect Scyst. PATIENTS AND METHODS: The study was performed in 33 patients (mean age 49.1 +/- 6.3 years) with chronic renal disease (Scr = 227 +/- 118 micromol/l) and BMI = 35.6 +/- 1.8 kg/m2, and in 78 patients (mean age 43.4 +/- 5.1 years) with chronic renal disease (Scr = 245 +/- 111 micromol/l) and BMI = 24.0 +/- 1.8 kg/m2. Glomerular filtration rate (GFR) was determined using renal inulin clearance (Cin) under conditions of stabilized plasma concentrations and water loading. Scyst was measured using immunonephelometry. For statistical evaluation, linear regression analysis and receiver-operating characteristic (ROC) curve analysis were used. RESULTS: A significant correlation (r = 0.956, p < 0.001) between l/Scyst and Cin was demonstrated in patients with BMI > or = 30 kg/m2 (Group A). Similarly, a significant correlation (r = 0.900, p < 0.001) between l/Scys and Cin was found in patients with BMI < 30 kg/m2 (Group B). There was no significant difference between the regression straight lines characterizing these relationships. ROC curve analysis (using a cut-off value for Cin = 30 ml/min/1.73 m2) did not show significant differences in AUC, sensitivity and specificity for Scyst between obese and nonobese patients. CONCLUSION: The results suggest that evaluation of GFR based on Scyst in obese patients need not differ from that in nonobese ones.     

Inhibition of nuclear factor-kappaB activation by pyrrolidine dithiocarbamate prevents chronic FK506 nephropathy

BACKGROUND: Chronic tacrolimus (FK506) nephrotoxicity is characterized by renal fibrosis with interstitial inflammation. Since nuclear factor-kappaB (NF-kappaB) plays a key role in chronic inflammatory diseases including renal disease, the present study was conducted to elucidate the role of NF-kappaB in the pathogenesis of chronic FK506-induced nephropathy. METHODS: FK506 (1 mg/kg/day, SC) was administered daily to rats maintained on low sodium diet for 42 days. Some rats were treated with a putative NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC; 100, 200 mg/kg/day, by gavage). The renal function, renal histology, renal NF-kappaB-DNA binding activity and gene expression profile were examined. RESULTS: FK506 caused a decline in glomerular filtration and induced characteristic renal morphologic changes including arteriolopathy, tubular atrophy and interstitial fibrosis. FK506 markedly activated renal cortical NF-kappaB-DNA binding. PDTC administration inhibited NF-kappaB-DNA binding activity in a dose dependent manner. With higher dose, NF-kappaB-DNA binding activity was decreased to a control level. PDTC had little effect on FK506-induced renal dysfunction. Renal cortical monocyte/macrophage infiltration observed in FK506-treated rats was dramatically suppressed by PDTC. FK506 up-regulated renal cortical gene expression of chemoattractant proteins, monocyte chemoattractant protein-1 (MCP-1) and osteopontin. PDTC significantly blocked MCP-1 gene expression but had no effect on osteopontin gene expression. Tubular atrophy and tubulointerstitial fibrosis, but not arteriolopathy, were significantly attenuated by PDTC. FK506 increased renal mRNA expression of fibrogenic molecules and extracellular matrices that also were attenuated by PDTC treatment. CONCLUSIONS: NF-kappaB plays an important role in mediating cortical monocyte/macrophage infiltration and in the pathogenesis of tubular injury and interstitial fibrosis in experimental FK506-induced chronic nephropathy.