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:2.3.1.109 (AST)
6,066 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to evaluate the protective or deleterious effects of endogenous nitric oxide (NO) on liver cells during hepatic ischemia-reperfusion (IR) in the rat. Injury to hepatocytes and endothelial cells was evaluated by determining cytolysis-marker activity in plasma (alanine transaminase [ALT]; aspartate transaminase [AST]) and plasma hyaluronic acid (HA) concentration. Clamping the hepatic pedicle for 45 minutes caused a significant increase in plasma AST and ALT activity after 30 minutes of reperfusion, which reached a maximum (+270% and +740%, respectively) after 6 hours of reperfusion. Plasma HA concentration was significantly higher (+130%) only after 6 hours of reperfusion. Administration of a nonselective NO synthase (NOS) inhibitor, Nomega-nitro-L-arginine (L-NNA; 10 mg/kg iv), 30 minutes before IR, caused marked aggravation of postischemic liver injury, as shown by plasma ALT and AST activity and HA concentration. This deleterious effect was partially prevented by the simultaneous injection of L-arginine, the endogenous NO precursor (100 mg/kg iv). Interestingly, L-arginine alone limited postischemic damage (AST, -25%; ALT, -45%; HA, -21% vs. untreated IR rats at 6 hours reperfusion). Pretreatment with the Guanosine 3':5'-cyclic monophosphate-independent vasodilator, prazosin, partially reversed L-NNA effects, but it did not protect untreated IR animals. Pretreatment with aminoguanidine, a selective inhibitor of inducible NOS, did not aggravate hepatic IR injury. Thus, endogenous NO, probably produced by an early and transient activation of a constitutive NOS, protects both hepatocytes and endothelial cells against liver ischemia-reperfusion injury, and this effect is not entirely a result of vasorelaxation.
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PMID:Hepatoprotective effect of endogenous nitric oxide during ischemia-reperfusion in the rat. 1005 83

We investigated the protective effect of urinary trypsin inhibitor (ulinastatin: UTI) in vitro, in relation to the neutrophil activity in hepatic ischemia/reperfusion (I/R) injury. The rat liver was removed and preserved in cold Ringer's lactate solution for 60 min, followed by 120 min of reperfusion with oxygenated perfusate. The rats were divided into four groups (n = 8 in each group). The livers were perfused with Krebs-Henseleit (K-H) solution containing no additives in group 1, 50,000 U/kg of UTI in group 2, 3.5 x 10(6) of neutrophils in group 3, and both neutrophils and UTI in group 4. In group 3, the AST and ALT levels were always higher than those in other three groups at any point evaluated (P < 0.01) and the LDH levels were observed to be significantly higher than those in other three groups at 0, 5, 10, 60, and 90 min after reperfusion (P < 0. 01). These increase were suppressed by additional pretreatment with UTI in group 4. The bile flow during reperfusion was significantly suppressed in group 3 compared to that of group 4, at both 30 (P < 0. 01) and 60 (P < 0.05) min after reperfusion. The MPO activity after reperfusion in group 3 also significantly increased compared to other three groups (P < 0.01). These data thus suggest that UTI ameliorated the ischemia/reperfusion injury in vitro by inhibiting of neutrophil accumulation in the postischemic liver.
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PMID:Protective effects of ulinastatin against ischemia-reperfusion injury. 1006 23

We previously reported that in vitro hypoxic condition enhanced VEGF level and its receptor expression in hepatic cancer cell line, HepG2. Transcatheter hepatic arterial embolization (TAE) therapy is one of the vasculo-occlusive and hypoxic challenges to hepatocellular carcinoma (HCC). Therefore, we examined the level of VEGF in sera of patients with HCC who underwent TAE during the course of the treatment. Thirty-eight patients with HCC and hepatitis C virus-positive cirrhosis were studied. Peripheral blood samples were taken before and 1, 3 and 7 days after TAE with informed consent. The serum levels of VEGF as well as hepatocyte growth factor (HGF), another hepatic remodeling factor, were measured. The molar ratio (BTR) of serum branched chain amino acid (BCAA) to tyrosine (Tyr), the serum levels of AST, ALT and LDH were also examined. Although the level of AST, ALT and LDH reached the peak value within 1 day after TAE, VEGF level increased significantly 7 days later. On the other hand, there were no significant alterations in the levels of HGF and BTR during the course of TAE. Although the level of HGF was significantly correlated with the level of VEGF before TAE, this correlation was no more observed after TAE. These data collectively suggest that VEGF may be secreted in response to clinical hypoxic intervention, TAE, independent of HGF or altered amino acid metabolism. VEGF may play a role as a sensitive marker for tumor ischemia.
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PMID:Serum vascular endothelial growth factor in the course of transcatheter arterial embolization of hepatocellular carcinoma. 1033 62

The effects of ozone treatment on the injury associated to hepatic ischemia-reperfusion (I/R) was evaluated. Ozone treatment (1 mg/kg daily during 10 days by rectal insufflation) is shown to be protective as it attenuated the increases in transaminases (AST, ALT) and lactate levels observed after I/R. I/R leads to a decrease in endogenous antioxidant (SOD and glutathione) and an increase in reactive oxygen species (H2O2) with respect to the control group. However, ozone treatment results in a preservation (glutathione) or increase (SOD) in antioxidant defense and maintains H2O2 at levels comparable to those in the control group. The present study reports a protective effect of ozone treatment on the injury associated to hepatic I/R. The effectiveness of ozone could be related to its action on endogenous antioxidants and prooxidants balance in favour of antioxidants, thus attenuating oxidative stress.
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PMID:Protective effect of ozone treatment on the injury associated with hepatic ischemia-reperfusion: antioxidant-prooxidant balance. 1049 75

This study was performed to determine whether human urinary soluble thrombomodulin plays a role in liver ischemia-reperfusion injury. Liver ischemia was induced in two groups of dogs. Group 1 was exposed to 60 min ischemia, and group 2 was exposed to 60 min ischemia after preischemic administration of human urinary soluble thrombomodulin. In group 1, the thrombin-antithrombin complex and hyaluronic acid were significantly elevated after ischemia, compared with the preischemic values. While liver issue blood flow and the plasmin-alpha(2)-plasmin inhibitor complex significantly decreased, AST, ALT and m-AST dramatically increased after reperfusion. In group 2, the increase in the thrombin-antithrombin complex and hyaluronic acid was significantly suppressed, and AST, ALT and liver tissue blood flow significantly improved, compared with group 1. Histologically, in group 2, the hepatic tissue structure, including endothelial cells, was relatively intact. These findings suggest that administration of thrombomodulin inhibits endothelial cell injury and coagulopathy and offers protection from liver ischemia-reperfusion injury.
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PMID:Protective effect of human urinary thrombomodulin on ischemia- reperfusion injury in the canine liver. 1081 Feb 13

One of the changes produced by ischemia and reperfusion is endothelin (ET)-mediated constriction of the hepatic vascular bed. This leads to microcirculatory disturbances and reduced blood flow, thereby causing local hypoxia and liver damage. Our aim was to induce stepwise changes of microvascular vessel diameters so as to define the best protective vessel width that could be produced by drug therapy and thereby to minimize ischemia/reperfusion injury. The mixed ET receptor antagonist bosentan was used in different dosages in a rat liver ischemia/reperfusion model with splenocaval shunt. In vivo microscopy was performed 30-90 min after reperfusion and local hepatic tissue pO2 was determined, together with aspartate aminotransferase/alanine aminotransferase (AST/ALT). After ischemia, sinusoidal diameters were significantly reduced to 76 +/- 7% of those in the control group. After the administration of bosentan in dosages of 0.1, 1, and 10 mg/kg body weight iv and 10 mg/kg body weight intraportally we found diameters of 83 +/- 4, 98 +/- 2, 109 +/- 6, and 137 +/- 19%, respectively. Perfusion rate and leukocyte-endothelium interactions showed dependence on sinusoidal diameters, with the best results in the group where preischemic sinusoidal vessel width had been maintained. Local tissue pO2 and transaminase levels also showed that oxygen supply was sufficient and that hepatocellular injury was most minimized in this group. Graduated blocking of ET receptors allows stepwise regulation of sinusoidal and postsinusoidal venular vessel width and offers a treatment strategy for pathophysiological situations that are associated with ET-induced vasoconstriction. The results suggest that maintenance of preischemic microvascular diameter is the best therapeutic approach.
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PMID:Controlled vasoregulation of postischemic liver microcirculation--a therapeutic approach. 1107 63

During ischemia-reperfusion an imbalance between endothelin (ET) and nitric oxide (NO) can be responsible for microcirculatory disturbances. The aim of this study was to restore the ET/NO balance to reduce the ischemia-reperfusion injury. Hepatic ischemia was induced for 30 min in 56 Wistar rats. Sham operation, ischemia and treatment groups with the ET receptor antagonist (ERA) bosentan (1 mg/kg body weight i.v.) and the NO donor L-arginine (400 mg/kg body weight i.v.) were performed. For evaluation of hepatic microcirculation in vivo microscopy was carried out 30-90 min after reperfusion. Local hepatic tissue PO2, laser Doppler flow and aspartate aminotransferase/alanine aminotransferase (AST/ALT) levels were measured. Increased ET caused sinusoidal constriction after reperfusion to 76% of the sham group (p < 0.05), leading to significant decrease in perfusion rate (82%), liver tissue PO2 (6.9 mmHg) and erythrocyte flux (45.2% of sham group). Hepatocellular damage could be detected 6 h after reperfusion by AST/ALT increase (p < 0.05). Sinusoidal diameters were maintained at baseline in the ERA (98%) and NO (102%) groups (p < 0.05). Increased percentage of leukocytes sticking in sinusoids (144%) and venules (435%) was reduced by therapy to 110/253% (ERA) and 111/324% (NO), respectively (p < 0.05). Perfusion rate was increased to 93 and 94% (p < 0.05 vs ischemia). Local hepatic tissue PO2 was improved 30 min after reperfusion in the ERA (11.0 mmHg) as well as in the NO group (11.5 mmHg; p < 0.05 vs ischemia). Measurement with a laser Doppler flow meter revealed significant improved erythrocyte flux in both therapy groups (p < 0.05 vs ischemia). Also, the post-ischemic AST/ALT increase was reduced by therapy. In conclusion, ET evokes strong constriction of post-ischemic sinusoids, leading to microcirculatory disturbances. The maintenance of the ET/NO balance by blocking ET receptors, or providing an NO donor, protects liver microcirculation and reduces hepatic ischemia-reperfusion injury.
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PMID:Endothelin/nitric oxide balance influences hepatic ischemia-reperfusion injury. 1107 80

The aim of this study is to assess the effect of accumulation of marginal liver graft criteria on the immediate outcome of liver transplantation (LT). The last 325 consecutive LT performed in 293 patients were analyzed retrospectively with respect to donor acceptance criteria. A marginal liver score was elaborated on the basis of the following features: donor > 60 years, ICU stay > 4 days, cold ischemia times > 13 h, hypotensive episodes < 60 mmHg > 1 h, bilirubin > 2.0 mg/dl, ALT > 170 U/l, and AST > 140 U/l were scored with the value 1. The use of dopamine doses > 10 microg/kg per min and peak serum sodium > 155 mEq/l were labeled with value 2. The cut-off point at 6 months after LT revealed 42 deaths (14%), with 65 graft losses (20%) and 32 (9%) retransplants. Recipient survival was not affected by the combined effect of marginal criteria. However, recipients transplanted with marginal livers with score 3 or more showed a decrease in graft survival (log-rank 6.21; P = 0.045) and an increase in delayed non-function rate (10 out of 33 vs 4 out of 156; P = 0.03). The use of marginal liver donors with more than three risk factors must be carefully reviewed or refused because of the cumulative dysfunction of these grafts.
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PMID:A proposal for scoring marginal liver grafts. 1111 5

The aim of this study was to explore the complex role of endothelins (ETs) in hepatic ischemia-reperfusion injury and to minimize this type of injury by nonselective ET receptor blockade. In an in vivo rat model, hepatic ischemia was induced for 30 min. The rats were divided into three groups: (1) sham operated, (2) untreated ischemic, and (3) group treated with the nonselective ET receptor antagonist bosentan (1 mg/kg body weight iv). Blockage of the ET system during ischemia-reperfusion was assessed by: (1) in vivo microscopic analysis, (2) measurement of local tissue PO2, (3) laser Doppler flowmetry, (4) transaminases, and (5) tumor necrosis factor (TNF)- serum levels. During liver ischemia, anoxia (mean liver pO2 decreased from 14.7 to 1.5 mm Hg) and TNF- (levels rose from 0 pg/mL to 145.3 pg/mL at the end ofischemia) were associated with the release of ETs. Immunoreactive ET-1 (ir-ET-1) plasma levels (basal levels: 12.1+/-1.8 pg/mL) went up by 2.6-fold (32.1+/-6.8 pg/mL) after 15 min and by 11.7-fold (142.1+/-32.6 pg/mL) after 120 min of reperfusion. Increased plasma levels of ir-ET-1 were associated with sinusoidal constriction to 77.6+/-7.1% of basal diameters. This constriction led to significant decreases in perfusion rate (77+/-3%), local tissue PO2 (6.9+/-2.7 mm Hg), and erythrocyte flux (61.7+/-13.8% of basal values). Hepatocellular damage, evaluated via the serum level of aspartate aminotransferase (AST, increase to 393.5+/-68.3 U/L, preoperative 23.9+/-2.0 U/L) was detectable 6 h after reperfusion (p < .05). Administration of bosentan before 30 min of ischemia significantly reduced ischemia-reperfusion injury and was associated with an increase of ir-ET-1 levels to 110.8+/-12.0 pg/mL and 94.1+/-25.0 pg/mL after 15 and 120 min of reperfusion. Sinusoidal diameters were maintained at nearly 100% in the treatment group instead of 77%, while perfusion rate (88+/-2%) and tissue PO2 (12.1+/-1.0 mm Hg) rose significantly in contrast with the nontreatment group (p < .05). Hepatocellular damage was reduced (AST levels after 6 h of reperfusion 244.0+/-34.4 U/L, p <.05), and leukocyte sticking and rolling were diminished (p < .01). In the treatment group, bosentan values of 5.6+/-0.7 and 2.9+/-0.4 ng/mL after 15 and 120 min of reperfusion were measured. In conclusion the release of endothelins is combined with microcirculatory disturbances and local hypoxia, thereby causing liver damage. By protecting the liver microcirculation, ET receptor blockade of both receptors at a low dose increased blood and oxygen supply to the liver and reduced hepatocellular injury. These results constitute the bases for further studies and transfer into clinical practice.
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PMID:Important role for endothelins in acute hepatic ischemia/reperfusion injury. 1129 59

The aim of the study was to evaluate myocardial perfusion in acute carbon monoxide poisoned patients using rest and stress Tc 99m-MIBI SPECT scintigraphy. There were 29 study patients (15 men and 14 women) aged from 14 to 46 years poisoned acutely with CO at home. Measurement of COHb, blood lactate level, duration of exposure and ECG examination were performed on admission to the Clinic. The enzymes activity (ALT, AST, CBK) were evaluated after 24 hours. The first rest Tc99m-MIBI SPECT was performed in all patients two to five days after intoxication. Fifteen of the patients underwent the control examination: stress and rest scintigraphy six months after CO exposure. Moving track exercise according to the Bruce protocol was used in each the patients. The control rest scintigraphy was performed 48 hours after exercise. Abnormal, differently intensified scans were noted in all the subjects: 5 patients had a I degree of pathological changes, 7 patients had II degree, 16--III degree and 1 patient had a IV degree of pathological changes. In 14 of the patients with pathological scintigraphic scans the normal EKG curves were noted. The mean COHb level was 35.0 +/- 7.22%, the blood lactate concentration was 4.4 +/- 3.7 mmol/L. The average duration of exposure was 108.4 +/- 163.9 min. Effort related ischemia was not noted in 10 of the patients who underwent control examination. An improvement in rest scintigraphic scans was stated in 12, and no changes were observed in 3 of the controlled patients. Deterioration was not found in any patient. No correlation between ECG results and scintigraphic image of myocardium was found. Tc 99m-MIBI SPECT scintigraphy is a more sensitive method than electrocardiography and measurement of enzymes activity for the evaluation of CO cardiotoxicity in acute poisoning. The method enables evaluation of the localization and disease extent.
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PMID:Usefulness of rest and forced perfusion scintigraphy (SPECT) to evaluate cardiotoxicity in acute carbon monoxide poisoning. 1145 Mar 57


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