Acute renal failure after cardiopulmonary bypass in related to decreased serum ferritin levels.
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Acute renal failure (ARF) requiring dialysis occurs in up to 4% of patients after cardiopulmonary bypass (CPB). CPB leads to the generation of intravascular free hemoglobin, resulting in increased endothelial and renal tubular cell free iron, which is associated with renal injury. Conversely, renoprotection is conferred by processes that upregulate heme and iron sequestration pathways, such as ferritin. This study evaluates the influence of free hemoglobin generation during CPB and the capacity to sequester free iron on the occurrence of post-CPB renal insufficiency. Thirty consecutive patients undergoing CPB were enrolled in the study. Serum creatinine, free hemoglobin, and ferritin were measured preoperatively, at the end of bypass, and 24 and 48 h after surgery. Renal injury, as determined by an increase in the serum creatinine of > or =25% (ARF) by 48 h after surgery, occurred in 40% (12 of 30) of patients, and dialysis was necessary in 6.6% (2 of 30). Free hemoglobin levels increased in all patients but did not correlate with postoperative ARF. However, patients with preoperative serum ferritin levels < or =130 microg/L, the median value for the group, had a sixfold greater likelihood of developing ARF compared to patients with levels above this value (P = 0.03). Lower serum ferritin levels appear to be associated with the development of ARF. Serum ferritin levels may signify intravascular as well as endothelial and renal epithelial cell ability to bind free iron generated during CPB-induced hemolysis, and thus may help provide information regarding the risk for ARF. (+info)
Risk factors for death and changing patterns in leptospirosis acute renal failure.
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The risk factors for death and changes in clinical patterns in leptospirosis (Weil's disease) have not been well studied. We retrospectively studied 110 patients with Weil's disease hospitalized in Brazil between 1985 and 1996. Univariate statistical analysis showed that nonsurvivors were older than survivors, and had higher frequency of oliguria, cardiac arrhythmia, dyspnea, and pulmonary rales. Logistic regression showed that the only independent factor associated with death was oliguria (odds ratio [OR] = 8.98). The presence of arthralgia (OR = 4.71), dehydration (OR = 6.26), dyspnea (OR = 17.7), and pulmonary rales (OR = 9.91) increased after 1994. These data suggest that in Weil's disease the clinical patterns have changed and the presence of oliguria is a risk factor for death. (+info)
Outcome in patients requiring renal replacement therapy after surgery for ruptured and non-ruptured aneurysm of the abdominal aorta.
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OBJECTIVES: to study the course of postoperative acute renal failure requiring renal replacement therapy (RRT) in patients with ruptured (RAAA) and non-ruptured (EAAA) aneurysm of the abdominal aorta (AAA) and to investigate the predictive value regarding outcome of parameters collected during the illness. DESIGN: retrospective study in a university hospital. MATERIALS AND METHODS: the records of 42 patients, 21 with RAAA and 21 with EAAA, were reviewed. RESULTS: overall mortality was 69%, 71% for RAAA patients and 66% for EAAA patients. RRT was started 9 (2-28) days - median (range) - postoperatively and continued during 9 (2-50) days. Renal function recovered in nine of the 13 survivors after 18 (2-50) days. Length of ICU stay was 50 (2-132) days for survivors vs. 19 (6-56) days for non-survivors. The systemic inflammatory response syndrome (SIRS) or need for vasoactive support was associated with poor outcome and the ability to wean from vasoactive or ventilatory support with improved outcome. CONCLUSIONS: RAAA and EAAA patients requiring postoperative RRT both had a high mortality. The ICU stay of non-survivors was shorter than that of survivors, who had a 75% chance of regaining renal function. The ability to wean from ventilatory and inotropic support may be of help in the clinical management of patients requiring RRT after AAA surgery. (+info)
Increased proximal tubular cholesterol content: implications for cell injury and "acquired cytoresistance".
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BACKGROUND: Acute renal failure (ARF) leads to secondary adaptive changes that serve to protect proximal tubules from subsequent ischemic or toxic damage [so-called "acquired cytoresistance" (CR)]. A characteristic of CR is increased plasma membrane resistance to attack. Therefore, this study sought to identify potential changes in plasma membrane lipid composition in CR tubules/renal cortex and, if present, to test whether they might mechanistically contribute to the CR state. METHODS: Renal cortices/isolated tubules were obtained from CR mouse kidneys (18-hr postinduction of ischemia reperfusion, myoglobinuria, or ureteral obstruction). Their plasma membrane phospholipid/cholesterol profiles were compared with those observed in either control tissues or tissues obtained one to two hours post-renal damage (that is, prior to emergence of CR). RESULTS: Either no changes or inconsistent changes in phospholipid profiles were observed in CR tissues. Conversely, CR (vs. control) tissues demonstrated a consistent 25 to 50% increase in membrane cholesterol content. To ascertain whether cholesterol impacts tubule susceptibility to injury, its levels were reduced in proximal tubule (HK-2) cells with either (a) mevastatin, (b) a cholesterol "stripping" agent, (c) cholesterol oxidase, or (d) cholesterol esterase. Then cell susceptibility to injury [adenosine 5'-triphosphate (ATP) depletion; Fe-mediated oxidant stress] was assessed. In each instance, cholesterol reductions dramatically sensitized to superimposed injury (for example, a 2 to 3 times increase in the % of lactate dehydrogenase release). When cholesterol levels were restored to normal in CR tubules (with a "stripping" agent), an increased tubule susceptibility to injury resulted. Because cholesterol decreases membrane fluidity, the impact of a membrane-fluidizing agent (A2C) on cell injury was assessed. A2C dramatically sensitized HK-2 cells to superimposed attack. CONCLUSIONS: ARF leads to an up-regulation of proximal tubule cholesterol content. The latter may then contribute to acquired CR, possibly by stabilizing the plasma membrane via its antifluidizing effect. (+info)
Long-term protective effect of UR-12670 after warm renal ischemia in uninephrectomized rats.
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BACKGROUND: The phospholipid platelet-activating factor (PAF) participates in the pathogenesis of renal ischemia/reperfusion injury, and in vitro, it induces synthesis of extracellular matrix proteins by mesangial and tubular epithelial cells. This study investigated the long-term effects of the potent orally active PAF antagonist UR-12670 in warm ischemic uninephrectomized rats, which was given according to different therapeutic schedules. METHODS: Uninephrectomized male Sprague-Dawley rats were divided into five groups and were followed for 52 weeks: rats without ischemia (SK); ischemic kidney for 60 minutes (SIK); ischemic kidney and UR-12670 from 0 to the 7th day (UR 0-7); ischemic kidney and UR-12670 from day 0 to 52 weeks (UR 0-E); and ischemic kidney and UR-12670 from day 8 to week 52 (UR 8-E). Two more groups (ischemic and UR treated) served to evaluate the UR-12670-protective effect on ischemic acute renal failure at one week. RESULTS: UR-12670 administration exerted functional and morphological protection against post-ischemic acute renal failure. The ischemic untreated (SIK) group developed progressive proteinuria from week 12. The onset of proteinuria in ischemic UR-12670-treated groups was delayed to the 24th week, and it was significantly lower than in SIK group throughout the study. Only SIK and ischemic-treated UR 0-7 rats presented with chronic renal failure, as shown by creatinine, creatinine clearance, glomerular filtration rate (GFR), and renal plasma flow (GFR 52 weeks: SK, 2525 +/- 267; SIK, 992 +/- 149; UR 0-7, 1551 +/- 385 microliter/min). Kidneys from the short-term treated group (UR 0-7) showed a reduction of glomerulosclerosis (SK, 14.4 +/- 3.7; SIK, 75.7 +/- 7.7; UR 0-7, 41. 5 +/- 8.5%) and vascular myointimal hyperplasia, but the tubulointerstitial damage (tubulointerstitial score: SK, 0.2 +/- 0. 2; SIK, 4.4 +/- 0.5; UR 0-7, 3.7 +/- 0.7) was similar to that in the ischemic untreated group. Long-term ischemic treated rats (UR 0-E, UR 8-E) did not develop chronic renal failure (GFR: UR 0-E, 2059 +/- 314; UR 8-E, 2410 +/- 208 microliter/min). In these groups, glomerulosclerosis (UR 0-E, 32.8 +/- 5.8; UR 8-E, 24.3 +/- 3.0%), tubulointerstitial damage (tubulointerstitial score: UR 0-E, 2.1 +/- 0.5; UR 8-E, 1.9 +/- 0.3) and vascular myointimal hyperplasia were significantly lower than in the ischemic untreated group. By in situ hybridization, an increase of transforming growth factor-beta1 mRNA expression in glomerular and tubular cells was observed in ischemic untreated and ischemic treated UR 0-7 rats. UR-12670 long-term treated rats showed a clear reduction of transforming growth factor-beta1 mRNA-positive glomerular cells. CONCLUSION: The chronic administration of the PAF antagonist UR-12670 attenuates the long-term effects of ischemia-reperfusion injury in uninephrectomized rats. The beneficial effect of this agent, even when given beyond the initial ischemia/reperfusion injury, suggests that PAF plays a role in the mechanisms of progression to late renal damage in this model. (+info)
Histologic and functional renal alterations caused by Bothrops moojeni snake venom in rats.
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Acute renal failure (ARF) is the main cause of death following snake bites by Bothrops species. In this study, we investigated the morphologic and functional renal disturbances caused by Bothrops moojeni venom in rats. Renal function was assessed based on creatinine and lithium clearances and on histologic examination of renal tissue 5 hr after the intravenous administration of 0.2 mg of venom/kg and 5 hr, 16 hr, and 48 hr after 0.4 mg of venom/ kg. A venom dose of 0.4 mg/kg produced renal tubule disturbances, including acute impairment of proximal and post-proximal tubule sodium handling associated with acute tubule necrosis. The glomerular filtration rate (GFR) decreased significantly and was accompanied by severe morphologic disturbances in the renal glomeruli. These functional and morphologic findings were observed in the absence of any change in mean arterial blood pressure. The decrease in GFR was not related to the presence of fibrin deposits in the glomerular capillary loops. These results suggest an early nephrotoxic action of B. moojeni venom involving significant morphologic and functional changes similar to those observed in snakebite-induced ARF in humans. (+info)
Chronic reduction in renal mass in the rat attenuates ischemia/reperfusion injury and does not impair tubular regeneration.
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It is not known whether a kidney with chronic structural and functional changes is more vulnerable to an acute renal insult, and whether its regeneration capacity after injury is altered. To study this question, Lewis rats were submitted 10 wk after 5/6 nephrectomy to an ischemic insult of 60 min (remnant kidney [RK] group). Functional and morphologic data of the RK group were compared with data obtained in 10-wk uninephrectomized (1K) and normal (2K) Lewis rats with unilateral and bilateral renal ischemia, respectively. The acute postischemic decrease in creatinine clearance was smallest in the RK group, followed by the 2K and 1K groups, respectively. At days 1 and 3, fewer proximal tubules in the outer stripe of the outer medulla of the RK and 2K groups had undergone acute tubular necrosis compared with the 1K group. The mean percentage of tubules with signs of regeneration was maximal at day 3 in the three experimental groups. At day 10, regeneration was almost complete in the three groups. The number of leukocytes (OX1+ cells) present in the RK before ischemia did not increase after ischemia/reperfusion injury (377 +/- 146 cells/mm2 at day 0) in contrast to the 1K and 2K groups. In the latter groups, the number of leukocytes had increased gradually, reaching a maximum at day 15 (1K: 960 +/- 308 cells/mm2) and day 10 (2K: 668 +/- 164 cells/mm2), respectively. In conclusion, this study has shown that an RK exhibiting chronic morphologic changes of interstitial fibrosis and tubular atrophy is protected against ischemia/reperfusion injury, and that its regeneration capacity is preserved. The reperfusion injury is not followed by further accumulation of leukocytes, which were already present in the RK before ischemia. (+info)
Protective effect of KB-R7943, a novel Na+/Ca2+ exchange inhibitor, on ischemic acute renal failure in rats.
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The effects of KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate), a novel Na+/Ca2+ exchange inhibitor, on ischemic acute renal failure (ARF) in rats were examined. ARF was induced by clamping the left renal pedicle for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function was markedly diminished in ARF rats. Pretreatment with KB-R7943 (10 mg/kg, i.v.) markedly attenuated the ARF-induced renal dysfunction. Histopathological examination of the kidney of ARF rats revealed severe renal damage, which was suppressed by KB-R7943. Activation of the reverse mode of Na+/Ca2+ exchange seems to play an important role in the pathogenesis of ARF. A selective Na+/Ca2+ exchange inhibitor may be useful in cases of ARF. (+info)