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:2.6.1.2 (alanine aminotransferase)
26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Replication competent adenoviruses with various E1 modifications designed to restrict their replication to tumor cells are being evaluated as oncolytic agents in clinical trials. In mouse models, we observed that such oncolytic adenoviruses showed greater hepatotoxicity than E1-deleted adenovirus vectors following intravenous administration. Additional studies in congenic BALB/c, nude, and beige/Scid mice demonstrated dose-dependent hepatotoxicity and indicated that beige/Scid was the most sensitive strain. Comparison of E1-containing viruses showed that hepatotoxicity correlated with expression of wild-type E1a in the liver. Pharmacokinetic analysis showed rapid increases in viral DNA levels in the liver with a virus containing wild-type E1a. This was correlated with rapid induction of TNF-alpha to high levels and with rapid elevation of serum ALT. Hepatotoxicity was significantly reduced for an adenovirus with deletions in the region E1a (dl01/07) or a virus lacking E1a. The results suggest a mechanism for hepatotoxicity involving virus-induced production of local TNF-alpha release and E1a-mediated sensitization of hepatocyte killing.
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PMID:Acute hepatotoxicity of oncolytic adenoviruses in mouse models is associated with expression of wild-type E1a and induction of TNF-alpha. 1538 Mar 58

In this study we sought to determine whether molecular mechanisms involved in the pathogenesis of fulminant hepatic failure are present in rabbits experimentally infected with rabbit hemorrhagic disease virus (RHDV). The activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, as well as bilirubin concentration, were found to be significantly increased 36 hours after infection. Infected animals also demonstrated significant decreases in factor VII activity, in the Fischer index, and in the deterioration of prothrombin time. The concentration of reduced glutathione was significantly decreased 36 hours after infection, and we noted a marked increase in the ratio of oxidized to reduced glutathione. Infected animals showed progressive decreases in liver activity of the antioxidant enzyme superoxide dismutase. Expression of hepatocyte growth factor and c-met was found to be progressively reduced from 24 hours after infection, during which time we detected no modification in messenger RNA (mRNA) levels of transforming growth factor (TGF)-alpha. TFG-beta 1 was overexpressed 24 and 36 hours after infection, and 36 hours after infection we detected a significant increase in TNF-alpha mRNA levels. Experimental RHDV infection also induced marked activation of nuclear factor-kappaB and a significant increase in inducible nitric oxide synthase mRNA levels from 24 hours after infection. Data obtained from this animal model support its usefulness in the investigation of potential novel therapeutical modalities aimed at neutralizing reactive oxygen species and hepatocyte growth inhibitors or enhancing hepatocyte responsiveness to mitogens.
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PMID:Pathogenic molecular mechanisms in an animal model of fulminant hepatic failure: rabbit hemorrhagic viral disease. 1551 90

The liver constitutes the first barrier in the control of hematogenous dissemination for Candida albicans of intestinal origin. The ability of this organ to limit the growth of the yeast and to mount an efficient inflammatory reaction is crucial in determining the outcome of the fungal infection. When rats infected with C. albicans are exposed to chronic varied stress, the cell recruitment is impaired at the site of the infection, the tissue reaction is highly disorganized in target organs and the infection evolution is more severe. At hepatic level, higher fungal burden is associated with hyphal form and the consistent presence of steatosis (fatty liver). Herein we aimed at characterizing the steatosis associated with C. albicans infection and to provide molecular evidence of the correlation among liver injury markers, stress products and the initiation of the inflammatory tissue reaction. After 3 days of stress and infection, we observed micro and macro steatosis in acinar zone 1 (specific lipid stain), higher lipid peroxidation and increased levels of serum alanine aminotransferase and gamma glutamil transferase. While infection triggered hepatic NO production and arginase activity, stress down-modulated both. Remarkably, defects in levels of TNF-alpha and NO were observed during the first step of the inflammatory response. Our results demonstrate that stress mediators down-regulate the acute inflammatory reaction in the hepatic scenario, promoting a major liver injury with particular immunopathological traits.
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PMID:High dissemination and hepatotoxicity in rats infected with Candida albicans after stress exposure: potential sensitization to liver damage. 1552 22

The triggering molecular mechanism of ischemia-reperfusion injury (IRI), which in clinical settings results in excessive and detrimental inflammatory responses, remains unclear. This study analyzes the role of the TLR system in an established murine model of liver warm ischemia followed by reperfusion. By contrasting in parallel TLR knockout mice with their wild-type counterparts, we found that TLR4, but not TLR2, was specifically required in initiating the IRI cascade, as manifested by liver function (serum alanine aminotransferase levels), pathology, and local induction of proinflammatory cytokines/chemokines (TNF-alpha, IL-6, IFN-inducible protein 10). We then investigated the downstream signaling pathway of TLR4 activation. Our results show that IFN regulatory factor 3, but not MyD88, mediated IRI-induced TLR4 activation leading to liver inflammation and hepatocellular damage. This study documents the selective usage of TLR in a clinically relevant noninfectious disease model, and identifies a triggering molecular mechanism in the pathophysiology of liver IRI.
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PMID:Cutting edge: TLR4 activation mediates liver ischemia/reperfusion inflammatory response via IFN regulatory factor 3-dependent MyD88-independent pathway. 1558 30

Gadolinium chloride (GdCl3) reportedly inhibits Kupffer cell function including TNF-alpha production and thereby improves organ dysfunctions after LPS challenge, particularly in partially hepatectomized (PH) mice. In addition, TNF-alpha reportedly promotes the regeneration of hepatocytes after PH. However, we have frequently seen GdCl3 treatment increase the mortality of normal mice after LPS injection. Therefore, we investigated this controversial issue in the present study. The mice treated by GdCl3 (10 mg/kg, i.v.) at 24 h before LPS challenge showed increased serum TNF-alpha and ALT levels after LPS challenge and a decreased mouse survival rate. The Kupffer cells from GdCl3-treated mice consistently produced a much larger amount of TNF-alpha following in vitro LPS stimulation than those of the control mice despite the fact that the Kupffer cells decreased in number and also demonstrated decreased superoxide production. Anti-TNF-alpha Ab before LPS-injection greatly improved GdCl3-induced mouse mortality and the degree of liver injury. In marked contrast, the increased amount of TNF-alpha induced by GdCl3 improved the survival after LPS challenge in PH mice because TNF-alpha promoted hepatocyte mitosis/regeneration in PH liver as evidenced by the fact that the inhibition of TNF-alpha before PH suppressed hepatocyte regeneration and decreased survival after LPS challenge. In conclusion, GdCl3 depletes the superoxide-producing Kupffer cells but conversely enhances the function of TNF-alpha-producing Kupffer cells, which thereby leads to LPS-induced mortality. Meanwhile, the increased TNF-alpha production induced by GdCl3 supports liver regeneration and increases the survival after LPS challenge in PH mice.
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PMID:Opposite effects of enhanced tumor necrosis factor-alpha production from Kupffer cells by gadolinium chloride on liver injury/mortality in endotoxemia of normal and partially hepatectomized mice. 1561 34

The effects of early hemofiltration on the serum levels of cytokines, pro- and anti-inflammatory balance and organ function in pigs with severe acute pancreatits (SAP) were studied. SAP pig model was induced by retrograde injection of artificial bile into the pancreatic duct. The pigs were randomly divided into SAP hemofiltration treatment group (HF group, n=8) and SAP non-hemofiltration treatment group (NHF group, n=8). In the HF group, the animals were subjected to high-volume and zero-balance hemofiltration therapy. The results showed that as compared with NHF group, MAP, CVP and PaO2/FiO2 were significantly increased (P<0.01), while HR, urinary protein content, serum ALT level, pulmonary coefficient and lung wet/dry ratio obviously decreased (P<0.05) in HF group. Under a light microscope, the pulmonary histologic scoring was lower that in HF group (P<0.01) and the lesions of renal and liver tissues were milder. However, there was no significant difference in the pancreatic histologic scoring between the two groups. Six h after establishment of the model, the serum levels of TNF-alpha, IL-1beta were lower, while the IL-10/ TNF-alpha ratio was higher in HF group (all P<0.05). It was suggested that early hemofiltration could effectively remove the serum cytokines TNF-alpha and IL-1beta in SAP pigs, elevate the ratio of IL-10/TNF-alpha, improve hemodynamics and alleviate the lesions of lung, kidney and liver tissues.
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PMID:Effect of early hemofiltration on pro- and anti-inflammatory responses and multiple organ failure in severe acute pancreatitis. 1564 91

The reactive oxygen species-sensitive transcription nuclear factor-kappaB (NF-kappaB) plays a pivotal role in the development of acetaminophen (APAP) hepatotoxicity. We investigated the efficacy of a diverse series of antioxidants in preventing APAP-induced hepatotoxicity. BALB/c mice were divided into four groups and provided with antioxidants incorporated into chow as follows: (1) control diet; or diet supplemented with (2) S-adenosylmethionine (SAMe); (3) green tea polyphenols (GrTP); or (4) (RS)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA). After 5 days on these diets, the animals were further subdivided into (A) given an IP injection with APAP (750 mg/kg), or (B) kept as untreated controls. The animals were sacrificed at 0, 4 h, and 24 h following APAP administration. PAP/vehicle induced marked decreases in hepatic reduced glutathione (GSH) levels and endogenous SAMe concentrations (46%) when compared to controls. APAP also caused severe centrilobular necrosis and marked increase in serum enzyme ALT activity (38-fold). Oral administration of antioxidants significantly attenuated the APAP-induced liver damage and depletion of hepatic GSH. There were profound increases in serum TNF-alpha levels at 4 h following APAP administration in nonsupplemented compared to antioxidant-treated animals, but no significant differences noted after 24 h. Serum amyloid A increased in APAP-challenged mice irrespective of antioxidant treatment. Finally, hepatic SAMe concentrations were drastically decreased 24 h following APAP administration, and these decreases were attenuated by pretreatment with antioxidants. In conclusion, these orally administered antioxidants with dissimilar properties provided protection against liver damage, supporting the potential use of antioxidant therapy in patients with APAP toxicity. This is the first report that GrTP and oral administration of PTCA and SAMe can provide protection against APAP injury in this model.
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PMID:Diverse antioxidants protect against acetaminophen hepatotoxicity. 1567 47

We assessed the prevention of hepatic fibrogenesis by water-extract of Panax notoginseng Buck F.H. Chen. (Arialiaceae) root (PNS) in Long-Evans rats with cinnamon coat color (LEC rats). LEC rats were divided into three groups A, fed on a basal diet (BD); B, fed on BD plus 1% PNS; and C), fed on BD plus 0.005% lycopene as a control. All rats were sacrificed at 26 weeks of age. The percentage of the total area involved by fibrosis was 1.46 +/- 0.47 in group A, 0.83 +/- 0.10 in B (P=0.0030, B vs A) and 0.91 +/- 0.45 in C (P=0.0035, C vs. A). The percentage of the total area that was stained for alpha-SMA was 0.56 +/- 0.34 in group A, 0.15 +/- 0.02 in B (P=0.0016, B vs. A and 0.11 +/- 0.01 in C (P=0.0025, C vs. A. In group B, malondialdehyde (MDA) in the liver was lower than in group C (P=0.007). In group C, the concentration of iron in the liver was lower than in group A (P=0.0053). Thus, PNS suppressed fibrogenesis through reduced generation of lipid peroxides. The mechanisms of this preventive effect of fibrogenesis with PNS were suggested to inhibit the stellate cell activity. Second objective of this study was to determine whether PNS affects hepatic microvascular dysfunction elicited by gut ischemia and reperfusion (I/R), since gut I/R causes hepatic microvascular dysfunction, and to investigate the role of nitric oxide (NO). Male Wistar rats were exposed to 30 min of gut ischemia followed by 60 min of reperfusion. Intravital microscopy was used to monitor the number of non-perfused sinusoids (NPS). In another set of experiments, PNS (1 g/kg per day intragastrically) was administered to rats for 7 days. In some experiments, dexamethasone (ST) (2 mg/kg per day intravenously) was administered. In control rats, gut I/R elicited increases in the number of NPS, and plasma TNF-alpha and ALT activities, and these changes were mitigated by the pretreatment with PNS. Pretreatment with an NO synthase inhibitor diminished the protective effects of PNS on the increase in NPS and plasma TNF-alpha levels, but not its effect on the increase in plasma ALT activities. Pretreatment with PNS increased plasma nitrite/nitrate levels. The responses caused by gut I/R were attenuated by the pretreatment with ST. Pretreatment with an NO synthase inhibitor did not affect the effect of ST. These results suggest that PNS attenuates the gut I/R-induced hepatic microvascular dysfunction and inflammatory responses such as TNF-alpha production in the early phase via enhancement of NO production, and sequential hepatocellular damage via its anti-inflammatory effect.
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PMID:A Korean herbal medicine, Panax notoginseng, prevents liver fibrosis and hepatic microvascular dysfunction in rats. 1569 47

Endotoxemia causes liver injury in which tumor necrosis factor (TNF)-alpha plays a significant role by inducing hepatic apoptosis. We here examined if such apoptosis is strictly dependent on TNF-alpha and which type of TNF receptor (TNFR) is involved, employing TNFR-1- and -2-knockout mice. Lipopolysaccharide (LPS) dose-dependently induced liver injury in both wild-type (WT) and TNFR-2-knockout mice as indicated by plasma ALT activities, whereas the injury was absent in TNFR-1-knockout mice. Similarly, apoptotic hepatocyte death was observed in WT and TNFR-2-knockout mice after LPS-injection, but not in TNFR-1-knockout mice. Plasma levels of TNF-alpha, interleukin (IL)-6, IL-10 and interferon-gamma as well as hepatic TNF-alpha levels increased equally in mice with either genotype after LPS-injection. LPS also enhanced equally the mRNA expression of Fas but not Fas ligand irrespective of either genotype, as measured by RNase protection assay. These findings suggest that apoptotic liver injury induced by LPS depends on TNF-alpha signaling through TNFR-1 but not via TNFR-2 or Fas-Fas ligand pathway.
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PMID:Liver injury induced by lipopolysaccharide is mediated by TNFR-1 but not by TNFR-2 or Fas in mice. 1571 73

This study was made to evaluate the effect of SB203580, a specific p38 MAP kinase inhibitor, on burn-induced hepatic injury as well as the activation of nuclear factor (NF)-kappaB in severely burned rats. Sprague-Dawley rats were divided into three groups: (1) sham group, rats underwent sham burn; (2) burn group, rats given third-degree burns over 30% total body surface area (TBSA) and treated with vehicle plus lactated Ringer solution for resuscitation 4 ml/(kg% TBSA); and (3) burn plus SB203580 group, rats given burn injury and fluid resuscitation plus SB203580 (10 mg/kg i.v., 15 min and 12 h after burn). Hepatocellular injury (measured by serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT)) and hepatocellular function (determined by the indocyanine green dye retention rate (ICG R15)) were assessed at 24 h post-burn. Liver histologic changes were also analyzed. Burn trauma resulted in increased serum aminotransferases concentrations, decreased ICG R15, elevated serum tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta levels and hepatic TNF-alpha and IL-1beta mRNA expressions, and worsen histologic condition. The level of Nuclear Factor (kappa) inhibitor (IkappaBalpha) in liver was decreased and DNA-binding activity of Nuclear Factor-kappaB (NF-kappaB) was increased after thermal injury. p38 MAP kinase was more significantly activated in liver harvested from burn rats than from shams. SB203580 inhibited the activation of p38 MAP kinase, reduced the levels of TNF-alpha and IL-1beta, and prevented burn-mediated liver injury. Both the IkappaBalpha level and NF-kappaB activity in the liver following burns was not affected by administration with SB203580. These findings suggest that (1) p38 MAP kinase activation is one important aspect of the signaling event that may mediate the release of TNF-alpha and IL-1beta and contributes to burn-induced liver injury and (2) p38 MAP kinase does not influence the activation of NF-kappaB directly in the liver of severely burned rats.
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PMID:p38 mitogen-activated protein kinase inhibition attenuates burn-induced liver injury in rats. 1577 88


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