Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cocaine produces hepatotoxicity by a mechanism that remains undefined but that has been linked to its oxidative metabolism. Endotoxin (lipopolysaccharide, LPS) is also a well-known cause of hepatic damage, where exposure to non-injurious doses of LPS increases the toxicity of certain hepatotoxins. This study was conducted to investigate the possible potentiation of cocaine-mediated hepatotoxicity (CMH) by LPS. Male CF-1 mice were administered oral cocaine hydrochloride for 5 consecutive days at a dose of 20 mg/kg with and without 12 x 10(6) EU LPS/kg given intraperitoneally 4 h after the last cocaine injection. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured as markers of liver injury. Blood and liver glutathione (GSH) levels were determined, as well as the activities of glutathione peroxidase (GPx) and catalase (CAT). In addition, the activity of liver glutathione reductase (GRx) was measured. The results demonstrate that endotoxin potentiated the hepatotoxicity of cocaine. Serum ALT and AST were significantly elevated with the combined cocaine and LPS treatment versus all other treatments. While cocaine alone resulted in centrilobular necrosis, the cocaine and LPS combination produced submassive necrosis. The increased hepatic GSH content and GRx activity observed with cocaine alone were not observed with the combination treatment, rendering the liver more susceptible to oxidative stress. Moreover, there was a significant decrease in the activities of hepatic GPx and CAT, particularly with the combination treatment. In conclusion, this study demonstrates that LPS potentiates the hepatotoxicity of cocaine as revealed by an array of biochemical and morphological markers.
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PMID:Endotoxin potentiates the hepatotoxicity of cocaine in male mice. 1213 32

The oxidative metabolism of cocaine by the microsomal monooxygenase enzymes has been postulated to be essential for cocaine mediated hepatotoxicity (CMH). Endotoxin (lipopolysaccharide, LPS), a well-known cause of hepatic damage, previously has been demonstrated to dramatically increase CMH. The mechanism of this interaction has not been clearly elucidated, but cocaine oxidative metabolism appears to sensitize hepatocytes so that subsequent exposure to small amounts of LPS can further augment CMH. This study was conducted to investigate if dimethylaminoethyl-2,2-diphenylvalerate (SKF-525A) pretreatment inhibits LPS potentiation of CMH. For 5 consecutive days, male CF-1 mice were administered daily SKF-525A (50 mg/kg) or sterile saline followed an hour later by cocaine (20 mg/kg) or sterile saline. Four hours following the last cocaine or saline treatment, the mice were administered sterile saline 12x10(6) EU LPS/kg, i.p. The mice were sacrificed 18 h later by decapitation. Pretreatment with SKF-525A reversed the hepatic injury caused by cocaine alone or cocaine and LPS treatments, as indicated by both histologic evaluation and serum alanine transaminase (ALT) and aspartate transaminase (AST) activities. In particular, SKF-525A completely reversed the effects of cocaine alone on liver and blood reduced gluthathione (GSH), glutathione peroxidase (GPx) and catalase (CAT) and hepatic glutathione reductase (GRx) activities. However, SKF-525A was ineffective against the effect of LPS alone on liver and blood GPx and CAT or on hepatic GSH and GRx, suggesting that these effects were not mediated by cytochrome P450 oxidative metabolism. The pattern of biochemical changes persisting with SKF-525A pretreatment in the LPS and cocaine group resembled those of the LPS alone group. The results suggest that cytochrome P450 oxidative metabolism of cocaine is largely responsible for CMH with potentiation by LPS achieved through a different mechanism involving oxidative stress.
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PMID:Inhibition of cocaine oxidative metabolism attenuates endotoxin potentiation of cocaine mediated hepatotoxicity. 1220 38

Using a rat model of septic shock we studied the effects of Evodia rutaecarpa, a Chinese herbal medicine with antimicrobial and anti-inflammatory activity, on haemodynamic parameters, biochemical markers of organ function and nitric oxide (NO) production. Anaesthetized rats challenged with a high dosage of endotoxin (Escherichia coli lipopolysaccharide; LPS; 50 mg kg(-1), i.v.) for 6 h showed a severe decrease in mean arterial pressure. This was accompanied by delayed bradycardia, vascular hyporeactivity to phenylephrine and increase in plasma levels of lactate dehydrogenase, aspartate aminotransferase, bilirubin and creatinine, as well as NOx (NO2- plus NO3-). Pretreatment with ethanol extract of E. rutaecarpa (25, 50 and 100 mg kg(-1), i.v.), 1 h before LPS, dose-dependently prevented the circulation failure, vascular hyporeactivity to phenylephrine, prevented liver dysfunction and reduced the NOx over-production in plasma in endotoxaemic rats. A selective inducible NO-synthase (iNOS) inhibitor, aminoguanidine (15 mg kg(-1), i.v.), also effectively ameliorated the above pathophysiological phenomenon associated with endotoxaemia so that the normal condition was approached. Endotoxaemia for 6 h resulted in a significant increase in iNOS activity in the liver homogenate, which was attenuated significantly by E. rutaecarpa pretreatment. In summary, E. rutaecarpa, at the dosages used, exerted these beneficial effects probably through inhibition of iNOS activity and subsequent modulation of the release of NO. These significant results may offer E. rutaecarpa as a candidate for the treatment of this model of endotoxaemia.
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PMID:Evodia rutaecarpa protects against circulation failure and organ dysfunction in endotoxaemic rats through modulating nitric oxide release. 1239 3

Hibiscus protocatechuic acid (PCA), a phenolic compound found in the dried flowers of Hibiscus sabdariffa L. (Malvaceae), was demonstrated to have an antioxidant effect in vitro and in vivo, and an antitumor property in our previous study. In the present study, we used lipopolysaccharide (LPS, an endotoxin) to induce rat liver inducible nitric oxide synthase (iNOS), and found that pretreatment with PCA decreased the liver iNOS and the serum total nitrite induced by LPS. Our investigation showed that pretreatment of rats with PCA (0.2 and 0.5 mmol/kg dosed by gavage) for 5 days significantly decreased the serum levels of the hepatic enzyme markers alanine- and aspartate aminotransferase (ALT, alanine aminotransferase; AST, aspartate aminotransferase) induced by the 6-h treatment with LPS (i.p.; 5 mg/kg). Histopathological evaluation of the rat livers revealed that PCA reduced the incidence of liver lesions induced by LPS, including neutrophil infiltration, congestion, and liver cell swelling induced by LPS in rats. We conclude that PCA, an antioxidant, presents an inhibitory potential on iNOS and hepatic damage induced by LPS.
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PMID:Hibiscus protocatechuic acid inhibits lipopolysaccharide-induced rat hepatic damage. 1249 Oct 40

Cocaine produces hepatotoxicity by a mechanism that remains undefined but has been linked to its oxidative metabolism. Endotoxin (lipopolysaccharide, LPS) is also a well-known cause of hepatic damage, and exposure to noninjurious doses of LPS increases the toxicity of certain hepatotoxins. Previously it was demonstrated that exposure to noninjurious doses of LPS dramatically increases cocaine-mediated hepatotoxicity (CMH). This study was conducted to investigate whether pretreatment with N-acetylcysteine (NAC), a glutathione (GSH) precursor and an antioxidant agent, inhibits LPS potentiation of CMH. For 5 consecutive days, male CF-1 mice were administered daily oral NAC (200 mg/kg) or sterile saline followed an hour later by cocaine (20 mg/kg) or sterile saline. Four hours following the last cocaine or saline treatment, the mice were administered 12 x 10(6) EU LPS/kg or sterile saline. For the cocaine alone and cocaine and LPS groups, NAC pretreatment significantly decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities with absence of necrotic hepatic lesions, indicating a reduction of liver injury. In addition, in all groups pretreated with NAC, hepatic GSH concentration was significantly increased, as were hepatic and blood glutathione peroxidase (GPx) and catalase (CAT) activities. In conclusion, the results demonstrate that NAC pretreatment exerted a protective effect against LPS potentia-tion of CMH.
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PMID:N-acetylcysteine pretreatment decreases cocaine and endotoxin-induced hepatotoxicity. 1252 69

The role of high mobility group-1 protein (HMG-1) in LPS- and TNF-alpha-induced lethal shock in galactosamine (GalN)-sensitized mice was investigated. No detectable HMG-1 levels were observed by immunoblotting analysis in plasma from untreated or GalN-sensitized BALB/c mice 5 h after LPS injection, although significant levels of HMG-1 were detected in plasma 6 h after the challenge. All GalN-sensitized BALB/c but not BALB/lps(d) mice succumbed by 6 h after LPS injection. When GalN-sensitized mice were injected with TNF-alpha, the presence of HMG-1 was seen at 5.5 h in plasma of BALB/c mice and at 6 h in BALB/lps(d) mice, although almost all GalN-sensitized BALB/c mice died by 6 h after challenge. The time-dependent phenomenon correlated with elevated serum aspartate aminotransferase (AST) levels and the appearance of apoptotic cells in livers. Administration of pooled plasma, equivalent to approximately 200 microg recombinant murine HMG-1, taken from mice on the verge of near death, did not result in induction of lethal shock in GalN-sensitized mice. Taken together with the late appearance of HMG-1 in moribund mice, these data suggest that HMG-1 does not decisively contribute to lethality in the GalN sensitization model.
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PMID:Does high mobility group 1 protein function as a late mediator for LPS- or TNF-induced shock in galactosamine-sensitized mice? 1253 98

OBJECTIVE: To establish a hepatocyte immunotoxicity model for screening of liver protective medications. METHODS: Cytotoxicity was induced by coincubating BCG-pretreated rat hepatocytes in vivo and with 10 mg/L LPS in vitro. Biphenyldimethylesterate (DDB), malotilate(MLT), silybin(SB) and glycyrrhizin (GRZ) were coincubated along with LPS to prevent the hepatocyte injury and verify the applicability and reliability of the model. AST, LDH and nitric oxide (NO) were measured in both the serum and supernatant. The liver and spleen index were calculated and the liver histopathologic changes were examined microscopically. RESULTS: Supernatant AST, LDH and NO in the BCG combined LPS group were increased in comparison with the control group (P<0.01). This increase was attenuated by the addition of DDB, MLT, SB and GRZ (P<0.05). The serum AST, NO and liver and spleen index were also increased significantly compared with the control group (P<0.01). Microscopic exam revealed serious histopathologic changes in the BCG combined LPS group. Hepatoxicity with associated liver enzyme elevation but histopathologic changes were attenuated by DDB, MLT, SB and GRZ. CONCLUSION: BCG combined LPS-induced hepatocyte immunotoxicity in an in vitro rat model may be a useful technique to assess the effectiveness of liver protective medications.
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PMID:[Establishment of BCG combined LPS-induced hepatocyte immunotoxicity model to assess liver protective effects] 1260 56

Despite the fact that septic shock is characterized by a decrease in systemic vascular resistance, the main cause of death is due to multiple organ failure. The organ dysfunction is usually attributed to cell death caused by overproduction of free radicals derived from inflammation. In the host infected by endotoxin (lipopolysaccharide, LPS), the expression and release of proinflammatory tumor necrosis factor-alpha (TNF-alpha) rapidly increases, and the formation of free radicals (e.g., superoxide anion [O2*-] and nitric oxide [NO*] in the present study) are inevitably overproduced. In this study, we present evidence that overall treatment of LPS rats with terbutaline, a beta2-adrenoceptor agonist, attenuates the delayed hypotension and ameliorates the tachycardia. Overproduction of TNF-alpha and NO* (produced by inducible NO synthase [iNOS] examined by Western blot analysis in the lung and the liver) is inhibited by treatment of LPS rats with terbutaline. In addition, treatment of endotoxemic rats with terbutaline also reduces the O2*- levels in the lung and the liver. Terbutaline also improves the liver (assessed by aspartate aminotransferase, alanine aminotransferase, total bilirubin, and albumin/globulin) and kidney (assessed by creatinine and uric acid) dysfunction induced by endotoxin. These findings suggest that the amelioration of circulatory failure and organs injury by terbutaline is associated with its suppression in TNF-alpha, O2*- and NO (via iNOS) production in animals with endotoxic shock.
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PMID:Inhibition by terbutaline of nitric oxide and superoxide anion levels of endotoxin-induced organs injury in the anesthetized rat. 1263 May 30

The liver is one of the major target organs affected in sepsis, and its failure always results in critical consequences. It has been reported that recombinant human interleukin 11 (rhIL-11), a pleiotropic cytokine, may be useful in the treatment of sepsis. However, the effect of IL-11 specifically on the hepatic failure in sepsis has not been evaluated. In the present study, we examined the effect of rhIL-11 on the hepatic injury in a rat endotoxemia model. Acute endotoxemia was induced in male Sprague-Dawley rats by intraperitoneal injection (i.p.) of bacterial lipopolysaccharide (LPS, 20 mg/kg). Immediately after injection of LPS, rats were treated with rhIL-11 (150 microg/kg, i.p.) or the vehicle. LPS treatment induced severe hepatic injury as revealed by marked increases in serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, extensive hepatocyte necrosis, tumor necrosis factor-alpha (TNF-alpha) mRNA, inducible nitric oxide synthase (iNOS) mRNA, and DNA-binding activity of nuclear factor-kappaB (NF-kappaB). In contrast, rhIL-11 treatment significantly ameliorated the LPS-induced hepatic injury, as judged by marked improvement in all these indices. In addition, rhIL-11 treatment markedly decreased LPS-induced mortality. These results indicate that rhIL-11 plays a significant protective role in LPS-induced hepatic injury in acute endotoxemia.
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PMID:A protective role of interleukin 11 on hepatic injury in acute endotoxemia. 1475 86

The inducible nitric oxide synthase (iNOS) is stimulated to produce large quantities of nitric oxide (NO) by proinflammatory stimuli, hemorrhagic shock, and a variety of cytokines. We have previously shown that cAMP profoundly inhibits hepatocyte iNOS expression in vitro. In this study, we tested whether glucagon, a hormone that increases cAMP in hepatocytes, could regulate hepatic iNOS expression and activity in vivo. Rats were injected intraperitoneally with lipopolysaccharide (LPS, 10 mg/kg) and treated with either saline or glucagon (500 microg/kg i.p.). Plasma and liver tissue were obtained 6 and 24 h after LPS. LPS induced increased iNOS mRNA, iNOS protein, and plasma levels of nitrite/nitrate that were all significantly decreased by glucagon treatment. The reduction in iNOS expression produced by glucagon was associated with a reduction in plasma AST and LDH levels, suggesting decreased LPS-induced hepatic injury. These data suggest that glucagon may participate in the in vivo regulation of hepatic iNOS expression after proinflammatory stimuli.
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PMID:Glucagon regulates hepatic inducible nitric oxide synthesis in vivo. 1525 89


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