Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022672 (acute tubular necrosis)
 2,175 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Following acute tubular necrosis (ATN), cytoresistance to further renal injury results. However, the initiating events and the subcellular determinants of this phenomenon have not been defined. Since tubular obstruction is a consequence of ATN, this study evaluated whether it alters tubular susceptibility to hypoxic damage. Extrarenal obstruction (ureteral ligation in rats) was used for this purpose to dissociate obstructive effects from those of ATN. Twenty-four hours following ureteral ligation or sham surgery, cortical proximal tubular segments (PTS) were isolated and subjected to hypoxic (15 or 30 min)/reoxygenation injury. Since oxidant stress, cell Ca2+ overload, and PLA2 attack are purported mediators of hypoxic/reoxygenation injury, degrees of FeS04, Ca2+ ionophore, and phospholipase A2-induced PTS damage also were assessed. The cell injury (% LDH release) which resulted from each of the above was consistently less in PTS obtained from obstructed kidneys. This cytoresistance: (a) did not require prior uremia to develop (seen with unilateral obstruction); (b) it did not appear to correlate with a tubular proliferative response (assessed by proliferating cell nuclear antigen expression); (c) it was uninfluenced by early tubular repair (unchanged by 24 hrs of obstruction release); and (d) it occurred without increased heat shock protein (HSP-70) or antioxidant enzyme (superoxide dismutase, catalase) expression. Total adenylate pools were higher in obstructed versus control PTS during injury; however, this appeared to be a correlate of the protection, rather than a mediator of it. In contrast, obstructed tubules manifested a primary increase in plasma membrane resistance to PLA2 attack (approximately 3-fold less lysophosphatidylcholine and free fatty acid generation in obstructed vs. control PTS during incubation with exogenous PLA2). In sum, these results indicate that: (1) tubular obstruction protects PTS from injury, suggesting that its development during ATN may initiate cytoresistance; and (2) this cytoresistance appears to be mediated, at least in part, by a direct increase in plasma membrane resistance to PLA2 and potentially other forms (such as, oxidant stress, cytosolic Ca2+ loading) of attack.
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PMID:Obstruction of proximal tubules initiates cytoresistance against hypoxic damage. 772 51

To determine the nephron segment distribution of tubular epithelial damage and regeneration and the proliferative activity of various nephron segments in human acute tubular necrosis (ATN) with an antibody to proliferating cell nuclear antigen (PCNA) and to compare the findings in native kidneys with ATN with those in transplant kidneys with ATN, archival tissues from 12 native and 21 transplant kidney biopsy specimens and nine transplant nephrectomy specimens were collected that all showed obvious morphological signs of ATN. Nineteen patients with transplant kidneys with ATN were immunosuppressed with cyclosporine and 11 were immunosuppressed with prednisone and azathioprine. There was a predominance of "regenerating" tubules (tubules with thin epithelium) in the distal nephron in native kidneys with ATN; in the transplant kidneys this was less conspicuous. The number of Tamm-Horsfall protein (THP)-positive tubules was decreased in all kidneys with ATN compared with normal human kidneys. In contrast, the number of THP-positive casts was much higher in all kidneys with ATN than in the normal kidneys. In transplant kidneys with ATN the number of THP-positive casts was substantially lower than in native kidneys with ATN. The macula densa appears to maintain its morphological integrity in kidneys with ATN. Both regenerating and normal appearing tubules expressed vimentin and HLA-DR. The proliferation index (PI; ie, percentage of PCNA-positive nuclei) of the renal tubular epithelium in normal control kidneys varied between 0.22 and 0.33, depending on the tubule segment. The highest PI was noted in the transplant kidneys with ATN not treated with cyclosporine (8.0), followed by the native kidneys with ATN (4.4) and the transplant kidneys with ATN treated with cyclosporine (4.3). We did not find any significant difference in the PI between the regenerating (5.0) and normal appearing (5.6) tubules. Proximal tubules (8.7) showed significantly higher PI values than distal tubules (3.5) in transplant kidneys with ATN. Our results show substantial differences between native kidneys and transplant kidneys with ATN. Tubular epithelial cell proliferation in human ATN is prominent and appears to correlate with the severity of ATN. Light microscopically normal appearing tubules and regenerating tubules participate equally in the regeneration of injured tubules. Cyclosporine may have an inhibitory effect on cell regeneration (proliferation) in human transplant kidneys with ATN.
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PMID:Human acute tubular necrosis: a lectin and immunohistochemical study. 786 54

The presence of delayed graft function (DGF) following cadaver donor renal transplantation is associated with inferior graft survival as well as decreased patient survival. Delay in onset of function eliminates a valuable indicator of allograft viability, which is not easily replaced by standard diagnostic procedures. The purpose of this study was to demonstrate that a new clearance technique could be used to measure renal function minute to minute and under conditions similar to those observed in humans in the immediate posttransplantation period. A monkey model was used to provide controlled conditions. Increasing levels of ischemic injury were produced in 12 Rhesus monkeys by renal hilum cross-clamping. Real-time measurements of glomerular filtration rate (GFR) were obtained from the rate of clearance of the extracellular fluid of the GFR agent 99mTc-DTPA, as measured with a specially designed external radioactivity counting device called the ambulatory renal monitor, or ARM. GRF was measured every 2-5 min as the slope (k) of the log of activity measured minute to minute versus time. GFR measurements were correlated with blood urea nitrogen (BUN), plasma creatinine (Cr), routine light microscopy, and measurement of proliferating cell nuclear antigen (PCNA), a marker of cell proliferation. Large changes in renal function due to ischemia or ureteral obstruction were observed within minutes. In addition, the rate constant on Day 1 was predictive of peak serum Cr(R =--0.86, R2=.74, p = .0001). Acute tubular necrosis (ATN) resolution was reflected more quickly when using the rate constant (Day 1) than when using either BUN or plasma Cr (Day 3-4). Because of renal functional reserve, BUN and plasma Cr were relatively insensitive indicators of mild to moderate reductions in GFR as compared with the rate constant. We conclude that ARM is a simple method which provide an accurate, near real-time GFR readout with potential applications not only for the clinical management of patients with DGF, but also as a research tool in acute renal failure (ARF).
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PMID:Real-time monitoring of renal function during ischemic injury in the rhesus monkey. 857 Aug 62

S-(1,2-Dichlorovinyl)-L-cysteine (DCVC), a model nephrotoxicant in mice, causes acute tubular necrosis and death at high doses. Our earlier studies revealed that renal tissue repair was critical for survival in mice with DCVC nephrotoxicity. The objective of this study was to investigate if increasing renal tissue repair could protect mice from the lethal outcome of DCVC. Male Swiss Webster (SW) mice were administered a low dose of DCVC (15 mg/kg, ip) 72 h before injection of a normally lethal dose of DCVC (75 mg/kg, ip); this resulted in 100% protection against the lethal effect of DCVC. Because DCVC caused approximately two fold decrease in cytosolic and mitochondrial beta-lyase activity, the possibility that DCVC protection may be caused by decreased bioactivation was examined. Mercuric chloride (HgCl2, 6 mg/kg), a nephrotoxicant with no effect on beta-lyase activity, was administered 96 h before a lethal dose of DCVC. This also resulted in 100% protection from the lethal effect of DCVC. In both studies total glutathione was unchanged at any time after the lethal dose of DCVC was administered, obviating the role of glutathione in protection. In both cases the augmented and sustained tissue repair induced by priming dose and documented by 3H-thymidine pulse labeling and immunocytochemistry for proliferating cell nuclear antigen resulted in 100% survival in spite of the extensive renal injury. These findings suggest that stimulation of renal tubular repair by the priming dose, through augmented cell division, and the resistance of new cells to mechanisms of progression of injury, underlies auto- and heteroprotection against DCVC. The molecular mechanisms may have potential application in pharmacotherapeutic intervention for treatment of acute renal failure.
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PMID:Role of tissue repair in survival from s-(1,2-dichlorovinyl)-L-cysteine-induced acute renal tubular necrosis in the mouse. 1273 Jun 12

Ischemic renal injury can be classified into the initiation and extension phase followed by the recovery phase. The recovery phase is characterized by increased dedifferentiated and mitotic cells in the damaged tubules. Suppression subtractive hybridization was performed by using RNA from normal and ischemic kidneys to identify the genes involved in the physiological response to ischemia-reperfusion injury (IRI). The expression of stathmin mRNA increased by fourfold at 24 h of reperfusion. The stathmin mRNA did not increase in sodium-depleted animals or in animals with active, persistent injury secondary to cis-platinum. Immunofluorescent labeling demonstrated that the expression of stathmin increased dramatically at 48 h of reperfusion. Labeling with antibodies to stathmin and proliferating cell nuclear antigen (PCNA) indicates that the expression of stathmin was induced before the upregulation of PCNA and that all PCNA-positive cells expressed stathmin. Double immunofluorescent labeling demonstrated the colocalization of stathmin with vimentin, a marker of dedifferentiated cells. Stathmin expression was also significantly enhanced in acute tubular necrosis in humans. On the basis of its induction profile in IRI, the data indicating its enhanced expression in proliferating cells and regenerating organs, we propose that stathmin is a marker of dedifferentiated, mitotically active epithelial cells that may contribute to tubular regeneration and could prove useful in distinguishing the injury phase from recovery phase in IRI.
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PMID:Identification of stathmin as a novel marker of cell proliferation in the recovery phase of acute ischemic renal failure. 1507 20