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Query: UMLS:C0022672 (acute tubular necrosis)
 2,175 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabolic and morphologic changes occurred in the kidneys of rats within 3 hours after inciting acute tubular necrosis by completely clamping the renal blood supply, by intramuscular injections of glycerol, and by subcutaneous injections of HgC12. Although the initial trend was for p-aminohippurate and tetraethylammonium transport to decrease and for oxygen consumption, ammonia production, and gluconeogenesis to increase after glycerol, all of these parameters changed in opposite directions after renal pedicle clamping and after subcutaneous HgC12 (4.7 mg. per kg;). In addition, early morphologic changes in glycerol-injected rats differed from those seen with pedicle clamping and low dose HgC12. With high dose HgC12 (25 mg. per kg.), the metabolic and morphologic changes were somewhere in between those seen with the other insults. Coinciding with early metabolic and morphologic changes, cardiac output and renal blood flow decreased soon after the glycerol was given. On the basis of our findings, we cannot ascribe all of the early metabolic and morphologic changes in the glycerol model to ischemia, and we postulate that the circulating heme proteins may be nephrotoxic to ischemic renal tissue.
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PMID:Early events in various forms of experimental acute tubular necrosis in rats. 112 11

The combination of fetal hydrops and sacrococcygeal teratoma (SCT), is considered to be lethal. We report two such babies who survived. Case 1 exhibited oliguric acute renal failure (ARF) immediately after birth, and severe respiratory insufficiency despite maximal ventilatory support and vasodilator infusions. Tumor resection on the 2nd day of life resulted in an immediate improvement in pulmonary function as reflected by the ratio of arterial to alveolar oxygen. Renal function returned in a pattern typical of recovery from acute tubular necrosis. Case 2, less desperately ill, developed nonoliguric ARF, in part due to deliberate fluid restriction during the 7 days that followed birth and preceded surgery. This resolved following liberalization of fluid intake that occurred at the time of tumor removal on the 7th day of life. The baby also had respiratory insufficiency that improved after surgery. Respiratory insufficiency may be a severe and life-threatening complication of SCT and hydrops fetalis. Pulmonary function may improve dramatically by removal of the tumor. Why this improvement occurs is unclear. Improvement of respiratory function may result from the elimination of excess tumor blood volume with an improvement of the ventilation-perfusion ratio. Alternatively, the tumor may be a source of vasoactive substances or extremely desaturated blood that leads to pulmonary hypertension and right-to-left shunting. Uncertainties in postnatal fluid shifts and exaggerated fluid compartment volumes demand close attention to details of renal function.
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PMID:The newborn with hydrops and sacrococcygeal teratoma. 176 33

Acute tubular necrosis (ATN) after renal transplantation is related to the duration of warm and cold ischemia and leads to temporary or permanent impairment of graft function. An increased incidence of ATN has been reported since the introduction of cyclosporin A. Kidney damage resulting from hypothermic storage is generated in part during reperfusion rather than during ischemia itself. Potential mediators of the reperfusion injury are oxygen-derived free radicals. Therefore, the influence of two oxygen radical antagonists, allopurinol and superoxide dismutase, was evaluated in syngeneic rat kidney transplantation with and without concurrent administration of cyclosporin A. At 15 h cold ischemia, 28-day survival increased from 8% (no treatment) to 22% (superoxide dismutase), 33% (superoxide dismutase and allopurinol), and 73% (allopurinol). Cyclosporin A cotreatment (10 mg/kg over 14 days) resulted in survival rates of 0%, 25%, 17%, and 50% for the respective treatment groups. The results of serum creatinine values and morphological evaluation of biopsies paralleled the survival rates. Cyclosporin A nephrotoxicity was evidenced by significant serum creatinine elevations throughout the 28-day period of observation. In conclusion, allopurinol significantly protects syngeneic rat kidney transplants against a critical duration of cold ischemia. Under the conditions of this experiment, allopurinol was clearly superior to superoxide dismutase treatment. Cyclosporin A nephrotoxicity was, however, not ablated by the oxygen radical antagonists employed.
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PMID:Protective effect of allopurinol and superoxide dismutase in renal isografts in cyclosporin A-treated rats. 178 Apr 91

With PHP as an oxygen carrier, histologic studies in ET showed changes of renal tubular epithelial cells at 2 weeks post ET, with normal structure by 3-12 months post ET. The renal functional effects of PHP were evaluated by ET (30%, N = 3; 50%, N = 1; 80%, N = 3) in seven healthy mongrel dogs. Blood, urine, and renal biopsy specimens were taken pre ET and at 0, 1, and 2 days, 2, 4, and 6 weeks, and 3, and 6 months post ET. Data were compared to modified criteria of acute tubular necrosis. All dogs tolerated the procedure well and survived for 1 year. Urine output was normal with elevation during the first 2 days in the 50 and 80% ET, followed by stable output by 2 weeks, ranging from 12 to 60 ml/kg/day. Blood urea nitrogen (BUN) and serum creatinine (SCr) were normal. BUN/SCr was normal. The urine to plasma osmolality ratios were 2.6 to 8.3 (normal greater than 1), and fractional percent excretions of sodium (FES) were stable throughout. No existence of broad granular pigmented casts (BGPC) in urine sediment were noted. Renal histologic evaluation of vacuolization in the renal tubules were seen to be dose-dependent and transient, with normal histology by 3-6 months post ET. Dose-dependent vacuole formation observed in the early weeks post ET with PHP showed no renal functional changes. Based upon the modified criteria for acute tubular necrosis, no histologic abnormalities were noted.
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PMID:Renal effects of a pyridoxalated-hemoglobin-polyoxyethylene conjugate solution as a blood substitute in exchange transfusions. 319 21

Acute tubular necrosis is a frequent occurrence following hypovolemic shock and human renal transplantation. Although this postischemic injury was originally thought to result from ischemia alone, it has recently been recognized that significant tissue injury can occur during the period of reperfusion. The demonstration of the oxygen free-radical-mediated postischemic reperfusion injury by Granger, Rutili, and McCord in ischemic cat intestine suggested that this mechanism might also be operative following renal ischemia. In the kidney, postischemic injury results in necrosis of the proximal renal tubule and accumulation of erythrocytes in the outer renal medulla. It has been proposed that the primary event leading to these pathologic changes is a free-radical-mediated injury to the endothelial cells in the inner stripe of the outer medulla. Experimental evidence in animals subjected to warm and cold ischemia supports a free-radical-mediated mechanism. The clinical significance of these findings is demonstrated in preclinical animal studies of renal transplantation in which approximately two-thirds of the injury following cold ischemia could be ablated by superoxide dismutase administered just prior to reperfusion or by allopurinol when administered both at the time of preservation and reperfusion or at the time of preservation alone.
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PMID:Free-radical-mediated postischemic reperfusion injury in the kidney. 329 86

Renal hypoperfusion such as occurs in shock creates an environment in which cellular injury and organ dysfunction can occur during the episode of shock as well as during reoxygenation and reperfusion. A severe decrement in oxygen delivery compromises energy (adenosine triphosphate) production, leading to various degrees of cell injury ranging from cell swelling to acute cortical necrosis. These different responses of the kidney to shock explain the multiple clinical presentations varying from an isolated loss of concentrating ability to prolonged anuria. Many cellular events contribute to renal cell injury, including cellular ATP depletion, cellular and mitochondrial calcium overload, and activation of phospholipases and oxygen radical formation. Recent clinical and experimental studies suggest that ATP-MgCl2, free radical scavengers, diuretics, vasodilators, and calcium channel blockers appear to be beneficial in preventing acute tubular necrosis after anoxic or severe hypoxic insults. Thus these agents may be helpful in altering the course of acute renal failure in shock patients and may decrease their morbidity and mortality.
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PMID:Renal response to shock. 377 12

Patients with renal disease are at risk of further deterioration of renal function and acute tubular necrosis when subjected to anaesthesia and surgery. Optimal fluid loading and careful selection of anaesthetic techniques and agents, appropriate monitoring and the use of mannitol and dopamine assist in the maintenance of renal blood flow and help preserve renal function in these patients. In association with renal failure, physiological changes in other systems result in reduced oxygen supply to the tissues, metabolic disturbances, impairment of the coagulation and immune defence mechanisms and an increased risk of cardiac and cerebrovascular catastrophe. Although many anaesthetic techniques including regional analgesia may be used successfully in these patients caution with most drugs, especially pethidine, phenoperidine, suxamethonium and all non-depolarising neuromuscular relaxants is recommended. Of the volatile anaesthetics currently available, halothane is the agent of choice. Oxygen therapy and close monitoring of cardiorespiratory function are necessary postoperatively.
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PMID:Anaesthesia for the patient with impaired renal function. 635 49

The class of nephrotoxins which are directly tubulotoxic in animal studies (cis-platinum, gentamicin, and cephaloridine) produce minimal histological changes in the human kidney. Such alterations do not correlate with the degree of organ dysfunction and fall into the broad category of what has been called 'acute tubular necrosis'. Some nephrotoxins (cyclosporine and amphotericin), acutely and chronically diminish renal perfusion, causing injury to renal parenchymal zones known to have limited oxygen a availability (medullary ray and inner stripe). In cyclosporine toxicity, the human and animal models appear equivalent. This is less clear with amphotericin where there appears to be a tubulotoxic component. Other nephrotoxic substances (contrast, nonsteroidal anti-inflammatory drugs) acutely alter renal perfusion, particularly affecting the medulla. In animal models of renal failure induced by these substances, there is an excellent correlation between medullary thick ascending limb injury and renal failure. Documentation of this phenomenon in human biopsies/autopsies is lacking, probably because of the lack of biopsy material and problems in defining medullary injury. Finally, in toxicological screening programs for nephrotoxic substances, there are groups of reactions which cannot be predicted and are thought to be mediated by immune mechanisms, i.e., immune complex glomerular disease, nil disease and interstitial nephritis.
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PMID:The pathology of nephrotoxic injury: a reappraisal. 784 19

The purpose of this study was to determine whether angiotensin converting enzyme inhibition could ameliorate renal ischemic injury. Both a chronic rat model and a rat isolated perfused kidney (IPK) model were used. Adult rats were subjected to 60 min of left hilar crossclamping and right nephrectomy. Captopril (1 mg/kg) was given intravenously 5-10 min prior to clamping (CAP-pre, n = 5), at reperfusion (CAP-post, n = 5), or 30 min after reperfusion (CAP-30 min post, n = 5). Other groups of rats received enalapril (0.8 mg/kg iv) in the same manner (ENAL-pre, n = 5; ENAL-post, n = 5; ENAL-30 min post, n = 4). Serum creatinine in the treated groups was compared to ischemic control (NS, n = 7) for 7 days. In the IPK experiments, kidneys were similarly treated with CAP or ENAL. Vascular resistance (VR) and oxygen consumption (O2 CON) were determined from pressure, flow, and oxygen tension data for 60 min after initial equilibration. In the chronic model, Day 2 serum creatinine was significantly lower in all treated groups vs ischemic control. By Day 7, serum creatinine remained significantly lower in all ENAL-treated groups and in the CAP-30 min post group, although other CAP-treated groups had appreciably, although not significantly, lower creatinines, too. Histologic examination of CAP-pre kidney revealed intact morphology compared to ischemic control where acute tubular necrosis was observed. In the IPK experiments, CAP- and ENAL-treated kidneys had VR values that were significantly lower than those of ischemic controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Captopril amelioration of renal reperfusion injury. 804 Nov 45

Heme proteins transport oxygen and facilitate redox reactions. Heme, however, may be dangerous, especially when free in biologic systems. For example, iron released from hemoglobin-derived heme can catalyze oxidative injury to neuronal cell membranes and may be a factor in post-traumatic damage to the central nervous system. We have shown that heme catalyzes the oxidation of low density lipoproteins which can damage vascular endothelial cells. The endothelium is susceptible to damage by oxidants generated by activated phagocytes, and this has been invoked as an important mechanism in a number of pathologies including the Adulte Respiratory Distress Syndrome (ARDS), acute tubular necrosis, reperfusion injury and atherosclerosis. Because of its highly hydrophobic nature, heme readily intercalates into endothelial membranes and potentiates oxidant-mediated damage. This injury is dependent on the iron content of heme and is completely blocked when concomitant hemopexin is added. Ferrohemoglobin, when added to cultured endothelial cells, is without deleterious effects, but if oxidized to ferrihemoglobin (methemoglobin), it greatly amplifies oxidant damage. Methemoglobin, but not ferrohemoglobin, releases its hemes which can then be incorporated into endothelial cells. Cultured endothelial cells, when exposed to methemoglobin but not ferrohemoglobin, cytochrome c or metmyoglobin, potentiate this oxidant injury. Stabilization of the methemoglobin by cyanide, haptoglobin or capture of the heme by hemopexin abrogates this effect. Paradoxically, more prolonged exposure of endothelium to heme or methemoglobin renders them remarkably resistant to oxidant challenge. Endothelium defends itself from heme by induction of the heme degrading enzyme heme oxygenase and the concomitant production of large amounts of the iron binding protein ferritin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heme and the vasculature: an oxidative hazard that induces antioxidant defenses in the endothelium. 808 43


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