Contribution of renal secreted complement C3 to the circulating pool in humans.
(25/7998)
Complement C3 produced within the kidney may be an important mediator of local inflammatory and immunological injury. The overall level of renal C3 production and consequently its contribution to the total circulating C3 level are, however, unknown. This was investigated by using the conversion of C3 from recipient to donor allotype following renal transplantation. The C3 F and S allotypes of 80 consecutive renal donor-recipient pairs (148 individuals) were determined by amplification refractory mutation system analysis. The extent of allotype conversion in C3 F/S mismatched recipients was quantified at different stages after transplantation, using an enzyme-linked immunosorbent assay specific for the HAV 4-1 polymorphism of C3 that is strongly associated with C3F. Twenty-one of the eighty recipients were potentially informative, i.e., were C3 SS recipients of C3 FF or FS donor kidneys. In the early postoperative period, donor-derived C3 (HAV 4-1-positive) was undetectable, increasing to 9.6% of the total circulating C3 at times of acute allograft rejection. When graft dysfunction occurred from causes other than rejection, donor C3 remained undetectable. After stable graft function was attained (3-13 mo after transplantation), donor C3 made up 4.5% of the total circulating C3 pool. Our findings demonstrate that human transplant kidney in the resting state is a significant source of extrahepatic C3. Its heightened local synthesis during rejection episodes suggests a possible pathogenic role for C3 in this immunological process. (+info)
Late consequences of acute ischemic injury to a solitary kidney.
(26/7998)
The sequelae of acute ischemic injury to a solitary kidney were assessed in rats subjected to right nephrectomy and transient occlusion of the left renal artery; control rats underwent right nephrectomy alone. Incomplete recovery from ischemic injury at 2 wk (serum creatinine levels of 1.1 +/- 0.2 versus 0.5 +/- 0.1 mg/dl, P < 0.05 for ischemia versus control) was followed by deterioration of renal function at 20 wk (serum creatinine levels of 1.7 +/- 0.4 versus 0.7 +/- 0.1 mg/dl, P < 0.05 for ischemia versus control). Morphologic studies showed that impairment of function after ischemic injury was associated with widespread tubulointerstitial disease. Some tubule segments were atrophic and others exhibited cystic dilation, so that the tubular cell volume fraction was reduced (37 +/- 4 versus 53 +/- 2%, P < 0.05), while the tubular lumen and interstitial volume fractions were increased (31 +/- 4 versus 23 +/- 2% and 29 +/- 2 versus 20 +/- 1%, respectively, both P < 0.05). Many glomeruli retained open capillary loops but were no longer connected to normal tubule segments (63 +/- 8 versus 15 +/- 7% of glomeruli, P < 0.05). There was a strong inverse correlation between the prevalence of such glomeruli and the GFR at 20 wk after ischemia (r2 = 0.79, P < 0.001). Tubulointerstitial disease at that time was accompanied by proteinuria and widespread segmental glomerular tuft injury. The occurrence of similar processes in human patients could contribute to the loss of graft kidneys that suffer ischemic injury during transplantation. (+info)
Acute renal impairment after immersion and near-drowning.
(27/7998)
Acute renal impairment (ARI) secondary to immersion and near-drowning is rarely described and poorly understood. A retrospective case-control study was performed: (1) to determine the incidence of ARI associated with near-drowning or immersion and (2) to define the clinical syndrome and to assess clinical predictors of ARI. Of 30 patients presenting after immersion or near-drowning, 50% were identified with ARI, with a mean admission serum creatinine of 0.24 +/- 0.33 mmol/L (2.7 +/- 3.7 mg/dl). These patients were a heterogeneous group: Eight had mild reversible ARI, three had ARI related to shock and multisystem failure, two had rhabdomyolysis-related ARI, and two had severe isolated ARI. Two patients required supportive hemodialysis and two died. Patients with ARI experienced more marked acidosis than control patients, as measured by serum bicarbonate (P < 0.001), pH (P < 0.001), and base excess (P < 0.001). There was also a higher admission lymphocyte count in the ARI group (P = 0.056). Dipstick hematuria on admission was significantly more common in patients with ARI (P = 0.016), and patients with 2 to 3+ of admission dipstick proteinuria had a higher peak serum creatinine than patients with less proteinuria (P < 0.05). Admission predictors of ARI by univariate logistic regression analysis included reduced serum bicarbonate (P = 0.002), pH (P = 0.001), and base excess (P < 0.001). The best predictor of ARI on multivariate analysis was a negative base excess (P = 0.01). In summary, acute renal impairment commonly occurs after immersion and near-drowning and is a heterogeneous condition. Although mild reversible renal impairment (serum creatinine < 0.30 mmol/L) (3.4 mg/dl) is usual, severe acute renal failure requiring dialysis can occur. It is recommended that any patient who presents after near-drowning or immersion should be assessed for potential ARI by serial estimations of serum creatinine, particularly when there is an increase in the initial serum creatinine, marked metabolic acidosis, an abnormal urinalysis, or a significant lymphocytosis. (+info)
The ET(A) receptor blocker LU 135252 prevents chronic transplant nephropathy in the "Fisher to Lewis" model.
(28/7998)
The effect of the orally highly bioavailable and specific endothelin A (ET(A)) receptor antagonist LU 135252 was assessed in a model of chronic renal allograft nephropathy. Kidneys of Fisher rats were orthotopically grafted to Lewis rats. Fisher autografts and kidneys after uninephrectomy served as controls. All animals received low-dose cyclosporin A (CsA; 1.5 mg/kg body wt) for 10 d after surgery. Allotransplanted animals were then randomized to receive standard diet or a diet designed to deliver 30 mg of LU 135252/kg body wt per d for 35 wk. BP was monitored telemetrically. Treatment with LU 135252 did not affect systolic or diastolic pressure. Indices of glomerulosclerosis (GSI), and tubulointerstitial and vascular damage were measured. Chronic transplant nephropathy was almost completely prevented by LU 135252 compared with untreated allografts or kidneys of uninephrectomized controls, i.e., GSI 0.7 +/- 0.12 versus 1.6 +/- 0.25 (P < 0.001) versus 0.7 +/- 0.06 (P < 0.001). Allograft weight and serum creatinine were significantly lower in treated versus untreated animals. The results are consistent with the notion that ET(A) receptor-mediated events play a role in the genesis of chronic transplant nephropathy. (+info)
Treatment of invasive fungal infections with amphotericin B colloidal dispersion in bone marrow transplant recipients.
(29/7998)
Amphotericin B colloidal dispersion (ABCD, AMPHOTEC, AMPHOCIL), a lipid complex of amphotericin B, was developed to reduce the nephrotoxicity of amphotericin B while retaining its antifungal efficacy. In this retrospective review, the efficacy and safety of ABCD were evaluated in 220 BMT recipients (167 allogeneic; 53 autologous) with suspected or documented life-threatening fungal infections (primarily Candida or Aspergillus species). Patients were treated in five open-label clinical trials of ABCD therapy. ABCD was administered intravenously once daily, median dose of 4 mg/kg, for up to 409 days (mean 23 days, median 16 days). Successful therapeutic response to treatment (complete or partial) was reported in 52% of the 99 evaluable patients with proven infection, and in 40% of all 220 patients. In the evaluable population, the response and mortality rates were 51% and 73%, respectively, in the allogeneic BMT patients, compared to 52% and 48% in the autologous BMT patients. The response rate for evaluable patients with Candida spp was 65%, 38% for patients with Aspergillus spp, and 42 % for patients with other or multiple fungal infections. In this patient population at high risk of nephrotoxicity due to concomitant cyclosporine and/or other nephrotoxic agents, ABCD did not cause renal dysfunction. Although the majority of patients had pre-existing renal impairment (median baseline serum creatinine 1.8 mg/dl), there was no trend towards increasing serum creatinine. No unexpected toxicities were observed. In conclusion, ABCD appears to be safe and effective for the treatment of severe fungal infections in BMT patients. (+info)
The renal lesions that develop in neonatal mice during angiotensin inhibition mimic obstructive nephropathy.
(30/7998)
BACKGROUND: Inhibition of angiotensin action, pharmacologically or genetically, during the neonatal period leads to renal anomalies involving hypoplastic papilla and dilated calyx. Recently, we documented that angiotensinogen (Agt -/-) or angiotensin type 1 receptor nullizygotes (Agtr1 -/-) do not develop renal pelvis nor ureteral peristaltic movement, both of which are essential for isolating the kidney from the high downstream ureteral pressure. We therefore examined whether these renal anomalies could be characterized as "obstructive" nephropathy. METHODS: Agtr1 -/- neonatal mice were compared with wild-type neonates, the latter subjected to surgical complete unilateral ureteral ligation (UUO), by analyzing morphometrical, immunohistochemical, and molecular indices. Agtr1 -/- mice were also subjected to a complete UUO and were compared with wild-type UUO mice by quantitative analysis. To assess the function of the urinary tract, baseline pelvic and ureteral pressures were measured. RESULTS: The structural anomalies were qualitatively indistinguishable between the Agtr1 -/- without surgical obstruction versus the wild type with complete UUO. Thus, in both kidneys, the calyx was enlarged, whereas the papilla was atrophic; tubulointerstitial cells underwent proliferation and also apoptosis. Both were also characterized by interstitial macrophage infiltration and fibrosis, and within the local lesion, transforming growth factor-beta 1, platelet-derived growth factor-A and insulin-like growth factor-1 were up-regulated, whereas epidermal growth factor was down-regulated. Moreover, quantitative differences that exist between mutant kidneys without surgical obstruction and wild-type kidneys with surgical UUO were abolished when both underwent the same complete surgical UUO. The hydraulic baseline pressure was always lower in the pelvis than that in the ureter in the wild type, whereas this pressure gradient was reversed in the mutant. CONCLUSION: The abnormal kidney structure that develops in neonates during angiotensin inhibition is attributed largely to "functional obstruction" of the urinary tract caused by the defective development of peristaltic machinery. (+info)
Renal hemodynamic effects of L-arginine and sodium nitroprusside in heart transplant recipients.
(31/7998)
BACKGROUND: Long-term treatment with cyclosporine A (CsA) induces vasoconstriction in the kidney and causes renal impairment. An altered L-arginine (L-Arg)/nitric oxide (NO) pathway may play a key role in CsA nephrotoxicity. METHODS: We studied the effect of L-Arg (dosage, 17 mg/kg/min over 30 min), the precursor of NO synthesis, and sodium nitroprusside (SNP; dosage, 1.0 microgram/kg/min over 30 min) on renal hemodynamics in a double-blind, placebo-controlled, randomized, three-way cross-over study comprising 12 stable cardiac transplant recipients on long-term CsA treatment, 10 patients with chronic nephropathy not receiving CsA, and 13 healthy controls. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were measured by paraaminohippurate (PAH) and the inulin clearance method, respectively. RESULTS: In healthy subjects, L-Arg induced an increase in RPF (P = 0.009) and GFR (P = 0.001). By contrast, L-Arg did not induce renal hemodynamic effects in heart transplant patients or patients with chronic nephropathy. SNP reduced RPF (P = 0.050) and GFR (P = 0.005) in patients with chronic nephropathy but did not affect renal hemodynamics in heart transplant recipients or in healthy subjects. CONCLUSIONS: These data indicate that L-Arg cannot be used to reverse CsA-induced renal vasoconstriction in heart transplant recipients under long-term CsA treatment, although these patients have a normal renal response to SNP. (+info)
In chronic nephropathies prolonged ACE inhibition can induce remission: dynamics of time-dependent changes in GFR. Investigators of the GISEN Group. Gruppo Italiano Studi Epidemiologici in Nefrologia.
(32/7998)
The Ramipril Efficacy in Nephropathy Core and Follow-Up Study found that > or =36 mo of continued ramipril therapy decreased substantially the risk of end-stage renal failure (ESRF) in patients with chronic nephropathies and a urinary protein excretion rate > or =3 g/24 h. This study investigates the time-dependent changes in GFR in these patients and in control subjects who were randomized to conventional therapy during the Core period and switched to ramipril during the Follow-Up study. Analyses included 150 patients (continued ramipril: n = 74; switched to ramipril: n = 76) who had at least three GFR measurements (including baseline) during the whole observation period and a subgroup of 43 patients (continued ramipril: n = 26; switched to ramipril: n = 17) who had at least six GFR measurements, including at least three on the Core and at least three on the Follow-Up study. Ramipril (1.25 to 5 mg/d) and conventional therapy were targeted at achieving a diastolic BP below 90 mm Hg. The main efficacy variables were GFR and ESRF (need for dialysis). Analysis was by intention to treat. Throughout the study, the mean +/- SEM rate of GFR decline (deltaGFR) was significantly lower in patients continued on ramipril compared to those switched to ramipril (0.51+/-0.09 versus 0.76+/-0.10 ml/min per 1.73 m2 per mo, P<0.03). In patients on continued ramipril who had at least six GFR measured--but not in control subjects--deltaGFR progressively improved with time and, in the cohort with the longest follow-up, decreased from (in ml/min per 1.73 m2 per mo): 0.16+/-0.12 (at 18 mo) to 0.10+/-0.05 (at 60 mo). This rate was about 10-fold slower compared to patients on conventional therapy during the REIN Core study. Analyses of the individual slopes found that at the end of the follow-up, 10 of 26 patients on continued ramipril therapy had a positive deltaGFR and another 10 patients had an improvement of deltaGFR while on ramipril therapy. DeltaGFR significantly improved in parallel with a significant reduction in proteinuria. Changes in deltaGFR (P = 0.0001) and proteinuria (P = 0.04) were significantly different in the two groups. Baseline characteristics and changes in systolic and diastolic BP and 24-h urine urea and sodium excretion were comparable. The present results offer evidence that in chronic nephropathies, the tendency of GFR to decline with time can be effectively halted, even in patients with remarkably severe disease. (+info)