Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A systemic BCG infection in mice induced multiple small granulomas located mainly in the periportal areas of the liver. Following systemic challenge of such mice with purified protein derivative of tuberculin (PPD), a rapidly developing hepatitis with diffuse intralobular mononuclear cell infiltration was precipitated, accompanied by high levels of aspartate transaminase in peripheral blood, hypoglycemia, focal hepatocyte necrosis, and accumulation of fibrinogen in liver. Bacterial lipopolysaccharide (LPS) also provoked acute hepatic damage both in BCG-infected mice and in mice pretreated with Corynebacterium parvum. PPD was not active in the latter. There were also lymphoid cell destruction and fibrinogen accumulation in the spleen of BCG-PPD-treated mice. Possible involvement of inflammatory and hepatotoxic mediators is suggested, and a T-lymphocyte-macrophage regulatory role in the pathogenesis of hepatitis is discussed.
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PMID:Tuberculin hypersensitivity hepatitis in mice infected with Mycobacterium bovis (BCG). 702 5

(AxT6)F1 hybrid mice received s.c. transplants from (AxT6)F1 mammary carcinomas. At 1, 2 or 4 weeks after tumour transplantation, the mice were bled to obtain plasma and then challenged with 25 micron E. coli lipopolysaccharide (LPS) endotoxin i.v. The mice were killed 24 hr later, further plasma was obtained and their liver ratios and spleen ratios were determined. A similar procedure was carried out on non-tumour-bearing mice. Progressive tumour growth was associated with an increase in the liver ratio. In parallel, mice with 4-week tumour transplant showed increased uptake of colloidal carbon particles and 51Cr-labelled sheep red blood cells in the liver. The plasma amino aspartate transaminase (AST) and the ornithine carbamoyl transferase (OCT) showed a constant rise in all groups of mice after LPS injection. However, at 24 hr after LPS injection, the AST level showed the greatest rise in mice with 4-week tumour transplants. By contrast, OCT, which is liberated only from hepatocytes, showed the greatest rise in non-tumour-bearing mice.
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PMID:Hyperphagocytosis and the effect of lipopolysaccharide injection in tumour-bearing mice. 745 24

Nitric oxide synthase produces NO, citrulline, water, and NADP at the expense of arginine, NADPH, and dioxygen. While citrulline has been considered to be an inert by-product of the high output inducible isoform of NO synthase (iNOS), we show here that immunostimulants induce a metabolic pathway in vascular smooth muscle cells, which enables them to regenerate arginine from citrulline. Regeneration of arginine from citrulline is accomplished by two urea cycle enzymes: arginino-succinate synthetase (AS) and argininosuccinate lyase (AL). Whereas AL is constitutive to vascular smooth muscle cells, AS mRNA and enzyme activity is markedly induced in cells by treatment with bacterial lipopolysaccharide (LPS). The induction of AS mRNA and activity by LPS follows a time course which mirrors that for iNOS but lags 1-2 h behind. As shown for iNOS, interferon-gamma does not itself induce AS but is synergistic with LPS. AS induction is suppressed by glucocorticoids, actinomycin D, and, to a lesser extent, cycloheximide. On the other hand, AS induction is unaffected by an excess of citrulline or the inhibitor of iNOS, N omega-methyl-L-arginine. Our results show the urea cycle enzymes AS and AL confer cells with the capacity to produce NO without a need for exogenous arginine. In conjunction with NOS, citric acid cycle enzymes that covert fumarate to oxaloacetate (fumarase and malate dehydrogenase) and oxaloacetate to aspartate (aspartate transaminase), AS and AL form a novel arginine-citrulline cycle that enables high output NO production by cells.
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PMID:Argininosuccinate synthetase mRNA and activity are induced by immunostimulants in vascular smooth muscle. Role in the regeneration or arginine for nitric oxide synthesis. 751 85

Previous research with pentoxifylline (PTX), a methylxanthine phosphodiesterase inhibitor, suggests that this drug may be capable of suppressing the activation of Kupffer cells and thereby help decrease liver injury after transplantation. To investigate this possibility, the current study sought to determine whether the release of O2- and tumor necrosis factor (TNF) from Kupffer cells in donor livers can be suppressed if the organs are exposed to PTX before preservation. In an in vitro experiment, rat livers were flushed with PTX (25 mg/kg body weight) in University of Washington (UW) solution or UW solution alone (control) and then and stored in UW solution for either 4 or 24 hours. Kupffer cells then were purified and their degree of activation determined by measuring O2- release and the production of TNF after lipopolysaccharide stimulation. In an in vivo experiment, a group of rats underwent orthotopic liver transplantation with grafts prepared in the same manner as in the in vitro study. TNF and aspartate transaminase (AST) were measured in blood samples taken 3 hours and 24 hours after transplantation. Compared with controls, the Kupffer cells from grafts pretreated with PTX produced significantly less O2- and TNF, and the recipients of PTX-pretreated grafts had lower levels of TNF and AST 3 hours after transplantation. The current data indicate that O2- and TNF production in liver grafts is suppressed by PTX pretreatment. Through its suppressive effect on Kupffer cells, PTX may help minimize preservation-reperfusion injury and improve graft survival.
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PMID:Effects of pentoxifylline pretreatment on Kupffer cells in rat liver transplantation. 770 82

Liver injury is common in patients following hemorrhage and sepsis. There are multiple etiologies for this liver injury which involve both decreased nutrient blood flow and direct cellular injury. Enteral nutrients vasodilate gut blood vessels and increase blood flow to the intestines and liver. Since enteral nutrients vasodilate gut blood vessels, we wondered whether luminal nutrition would prevent hepatic injury during shock states. We randomized Sprague-Dawley rats to saline or enteral nutrition via duodenal feeding tubes. Animals were then subjected to 60 min of hemorrhagic hypotension or intraperitoneal injection of lipopolysaccharide (LPS). Liver injury was assessed by measuring levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) before and after hemorrhage or LPS. Enteral nutrients significantly decreased liver injury following hemorrhage. AST increased from 246 +/- 17 to 1605 +/- 593 U/L in saline animals and 283 +/- 39 to 551 +/- 94 U/L in enterally fed animals. ALT increased from 60 +/- 4 to 726 +/- 355 U/L in saline animals and 61 +/- 6 to 161 +/- 38 U/L in enterally fed animals. Enteral nutrients did not significantly alter the increase in AST/ALT following LPS. These results indicate that enteral nutrients can decrease liver injury following hemorrhagic hypotension.
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PMID:Enteral feeding minimizes liver injury during hemorrhagic shock. 774 61

We examined the early changes after lipopolysaccharide (LPS) injection in chronically alcohol-fed rats with or without splenectomy. Administration of 2 mg/kg body weight LPS caused severe hepatic injury. The plasma aspartate aminotransferase (ASAT) activity was significantly higher in sham-operated rats 8 hr after LPS injection than in splenectomized rats. The plasma tumor necrosis factor (TNF) activity was also significantly higher 1 hr after LPS injection in sham-operated rats than in splenectomized rats. The plasma thromboxane (TX) B2/6-keto-prostaglandin (PG) F1 alpha ratio increased in sham-operated rats after LPS injection. Therefore, the balance of arachidonic acid metabolites was in a hypercoagulated state in sham-operated rats after the LPS injection. Neutrophil infiltration into liver tissue increased in sham-operated rats after the LPS injection. The cytokines and arachidonic acid metabolites released from the spleen after LPS injection in alcohol-fed rats may play important roles in severe hepatic injury.
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PMID:Roles of the splenic cytokines and arachidonic acid metabolites in severe hepatic injury after lipopolysaccharide injection in chronically alcohol-fed rats. 800 35

Nitric oxide (NO) and prostaglandins (PG) both possess the ability to induce vasodilatation and prevent the aggregation of platelets. The synthesis of these substances is increased following in vivo lipopolysaccharide (LPS) infusion, but their function during sepsis is incompletely understood. We studied the role of NO and PG in a murine model of chronic hepatic inflammation (Corynebacterium parvum injection), which is known to progress to sudden hepatic necrosis after LPS injection. NO synthesis, which is induced in hepatocytes by C. parvum treatment and in nonparenchymal cells by LPS treatment, was inhibited using NG-monomethyl-L-arginine (L-NMMA). High-dose aspirin (ASA) was used to block PG synthesis. Treatment with L-NMMA or ASA alone, in the absence of LPS, resulted in no increase in hepatic injury. C. parvum-treated mice that received both L-NMMA and ASA without LPS developed marked hepatic damage as reflected by increased hepatocellular enzyme release (aspartate aminotransferase and L-ornithine carbamoyl-transferase). Marked hepatic damage was seen after LPS administration, and ASA pretreatment alone had no effect on the LPS-induced hepatic injury, whereas L-NMMA markedly increased the hepatic damage. The combination of L-NMMA and ASA after LPS resulted in the greatest hepatocellular enzyme release, characterized histologically by intravascular thrombosis with diffuse infarction and necrosis. Simultaneous treatment with either PGI2 or L-arginine partially prevented this injury. These data demonstrate that NO and PG function synergistically to maintain hepatocellular integrity; thus increased synthesis of these mediators protects the liver from the pathophysiological effects of LPS in this model.
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PMID:Nitric oxide and prostaglandins interact to prevent hepatic damage during murine endotoxemia. 802 33

Earlier studies showed that hepatotoxicant-treated experimental animals were more susceptible than controls to the lethal effects of bacterial endotoxin. The exact mechanisms of this effect were not understood. In this paper we showed that nitric oxide (.NO) was produced in whole blood and in liver tissues of rats that had been treated with a nonlethal dose of CCl4 (1.3 g/kg) followed by a low dose of lipopolysaccharide (LPS) (100 micrograms/kg). EPR spectroscopy was used in this study to detect nitrosyl-protein complexes. Hemoglobin-nitrosyl complexes were detected in both whole blood and liver. By performing analyses of EPR spectra obtained from hepatocytes exposed to .NO, we were able to identify EPR signals attributable to nitrosyl-cytochrome P420 in rat liver. We found that nitrosyl complex formation in red blood cells and liver was inhibited by treatment with NG-mono-methyl-L-arginine, suggesting enzymatic biosynthesis of .NO. A small but significant inhibition of nitrosyl complex formation by gadolinium trichloride pretreatment was found in the liver, suggesting that Kupffer cells were also involved in .NO biosynthesis, because this treatment decreased Kupffer cells. There was a synergistic effect of CCl4 and LPS on the serum levels of the hepatic enzymes aspartate aminotransferase, alanine amino-transferase, lactate dehydrogenase, and sorbitol dehydrogenase, which are indices of parenchymal cell damage. NG-Mono-methyl-L-arginine treatment increased these hepatic enzyme activities, suggesting a protective role for .NO. EPR resonances at g approximately 2.48, 2.29, and 1.91, due to low-spin cytochromes P450/P420 (FE3+), were decreased in the livers of LPS-induced rats that had been previously treated with CCl4, indicating cytochrome P450/P420 destruction or at least a change in the valence state of the cytochrome P450/P420 heme groups to Fe2+ in the presence of .NO. Because nitrosyl-cytochrome P450 is not stable, the concomitant detection of nitrosyl-cytochrome P420 (Fe2+) could account, at least in part, for the decrease of the ferric low-spin heme groups. Our novel observations of hepatic nitrosyl species suggest that .NO plays an important role during hepatic injury caused by CCl4 in hosts exposed to endotoxin.
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PMID:Nitric oxide production during endotoxic shock in carbon tetrachloride-treated rats. 807 2

The bisbenzylisoquinoline (BBI) alkaloids chondocurine, cycleanine, tetrandrine and berbamine were tested for their capacity to suppress hepatic injury and production of tumor necrosis factor (TNF) induced by lipopolysaccharide (LPS) in mice primed with bacillus Calmette-Guerin (BCG). When administered for three consecutive days before LPS injection, chondocurine, cycleanine and tetrandrine (10 mg/kg/day) strongly suppressed serum alanine aminotransferase (EC 2.6.1.1.) and aspartate aminotransferase (EC 2.6.1.2.); however, berbamine gave only slight protection. Chondocurine, cycleanine and tetrandrine but not berbamine significantly reduced the level of TNF which peaked 2 hr after LPS injection. This study shows that BBI alkaloids prevent BCG/LPS-induced hepatitis at least in part by suppressing TNF production.
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PMID:Suppression of lipopolysaccharide-induced fulminant hepatitis and tumor necrosis factor production by bisbenzylisoquinoline alkaloids in bacillus Calmette-Guerin-treated mice. 825 Sep 73

Lipopolysaccharide binding protein (LBP) is a serum glycoprotein that complexes with lipopolysaccharide (LPS) to facilitate macrophage response to endotoxin. To determine the conditions that stimulate LBP production in vivo, we measured the induction of LBP in models of inflammation produced by LPS, Corynebacterium parvum, and turpentine injection. Plasma aspartate aminotransferase and alanine aminotransferase concentrations and hepatocyte fibrinogen synthesis were elevated in all models. Northern blot analysis revealed 17-, 14-, and 20-fold upregulation of hepatocyte LBP mRNA following treatment with LPS, C parvum, and turpentine, respectively. Peritoneal macrophage interleukin 6 and tumor necrosis factor production following endotoxin stimulation was augmented by cultured hepatocyte supernatants, suggesting increased LBP synthesis in these groups. The results show that LBP mRNA is induced during hepatic inflammation and suggest that LBP is an acute-phase protein important in regulating the in vivo response to endotoxin.
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PMID:Induction of hepatocyte lipopolysaccharide binding protein in models of sepsis and the acute-phase response. 841 76


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