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

---

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

1. The effects of racemic thalidomide (D[+]/L[-] alpha-phthalimido-glutarimide) on acetaminophen (AAP)-induced hepatitis were tested in male NMRI mice (n = 133) and quantified as serum activities of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT). 2. A 2.1-fold increase of GOT and a 1.9-fold increase of GPT activities (P < 0.001) were observed in mice treated perorally with 500 mg/kg of AAP plus 150 mg/kg of thalidomide (Thal). In the absence of AAP, Thal did not display any detectable hepatotoxic effects. 3. The Thal-induced exacerbation of AAP hepatotoxicity was completely inhibited by nicotinic acid amide, a selective inhibitor of poly(ADP-ribose) polymerase (PARP) (P < 0.0001), suggesting a possible influence of Thal on the hepatic metabolism of NAD-adenoribosylation. 4. We see the main application of nicotinic acid amide as for the combinational use in pharmaceutical preparations of AAP in order to avoid hepatic damage in patients treated with AAP and Thal.
...
PMID:Exacerbation of acetaminophen hepatotoxicity by thalidomide and protection by nicotinic acid amide. 759 Jan 13

Recently, we demonstrated the hepatoprotective effects of nicotinic acid amide, a selective inhibitor of poly(ADP-ribose) polymerase (PARP; EC 2.4.2.30) on mice suffering from acetaminophen (AAP)-hepatitis, suggesting that the AAP-induced liver injury involves a step which depends on adenoribosylation. The present study investigates the effects of a diet free of precursors of NAD, the substrate on which PARP acts, in female NMRI mice with AAP hepatitis and evaluates the influence of simultaneous ethanol consumption in these animals. Liver injuries were quantified as serum activities of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT). While AAP caused a 117-fold elevation of serum transaminase activities in mice kept on a standard laboratory diet, which was significantly exacerbated by ethanol and inhibited by nicotinic acid amide (NAA), adverse effects were noted in animals fed a diet free of precursors of NAD. In these animals, only minor increases of serum transaminase activities were measured in the presence of AAP, and unlike the exacerbation caused by ethanol in mice on a standard diet, the liver damage was inhibited by 50% by ethanol. A further 64% reduction of hepatitis was observed, when NAA was given to ethanol/AAP-mice. Our results provide evidence that the AAP-induced hepatitis and its exacerbation by ethanol can either be reduced by end-product inhibition of PARP by NAA or by dietary depletion of the enzyme's substrate NAD. We see the main application of NAA as for the combinational use in pharmaceutical preparations of acetaminophen in order to avoid hepatic damage in patients treated with this widely used analgesic.
...
PMID:Influence of diet free of NAD-precursors on acetaminophen hepatotoxicity in mice. 874 98

An array of therapeutically used analgetic and antirheumatic drugs causes severe liver damage. The present study investigates the hepatoprotective effects of inhibitors of NAD-dependent adenoribosylation reactions in analgesics-induced hepatic injury. Male NMRI mice were treated perorally with 500 mg/kg of acetaminophen, and the activities of both glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) were determined in serum. In addition, the activity of poly(ADP-ribose)polymerase (PARP) was quantified in liver cell nuclei. While the PARP-activity remained essentially unchanged, the acetaminophen-induced release of both GOT and GPT from injured liver cells could be inhibited by 90-99%, when mice were injected additionally with the selective PARP-inhibitors nicotinic acid amide, benzamide, caffeine, theophyline, and thymidine, respectively. We see the main application of inhibitors of adenoribosylation reactions as for the combinational use in pharmaceutical preparations of analgesics and antirheumatic drugs in order to avoid hepatic damage.
...
PMID:The influence of antagonists of poly(ADP-ribose) metabolism on acetaminophen hepatotoxicity. 874 16

1. An array of therapeutically used analgetic and antirheumatic drugs cause severe liver damage. The present study investigates the hepatoprotective effects of inhibitors of NAD-dependent adenoribosylation reactions and of antioxidants in analgesic-induced hepatic injury. 2. Male NMRI mice were treated PO with 500 mg/kg of acetaminophen, and the activities of both glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) were determined in serum. 3. The acetaminophen-induced release of both GOT and GPT from injured liver cells could be inhibited in a dose-dependent manner, when mice were injected additionally either with increasing amounts (from (25 mg/kg to 100 mg/kg i.p.) of the PARP-inhibitor nicotinamide, with increasing amounts (from 25 mg/kg to 100 mg/kg i.p.) of the antioxidant N-acetylcysteine, or with increasing amounts (from 50 mg/kg to 300 mg/kg i.p.) of the amino acid L-methionine. 4. A combination of both nicotinamide and N-acetylcysteine (at the low dose of 12.5 mg/kg i.p. each) results in a complete protection from acetaminophen-induced release of GOT and GPT from injured liver cells. 5. A combination of both L-methionine and N-acetylcysteine or nicotinamide (at the low dose of 12.5 mg/kg IP each) resulted also in complete protection from acetaminophen-induced release of GOT and GPT.
...
PMID:Protection from acetaminophen-induced liver damage by the synergistic action of low doses of the poly(ADP-ribose) polymerase-inhibitor nicotinamide and the antioxidant N-acetylcysteine or the amino acid L-methionine. 901 4

Poly (ADP-ribose) synthetase (PARP) is a nuclear enzyme activated by strand breaks in DNA, which are caused inter alia by reactive oxygen species (ROS). Here we report on (i) a new synthesis of a water-soluble and potent PARP inhibitor, 5-aminoisoquinolinone (5-AIQ) and (ii) investigate the effects of 5-AIQ on the circulatory failure and the organ injury/dysfunction caused by haemorrhage and resuscitation in the anaesthetized rat. Exposure of human cardiac myoblasts (Girardi cells) to hydrogen peroxide (H(2)O(2), 3 mM for 1 h, n=9) caused a substantial increase in PARP activity. Pre-treatment of these cells with 5-AIQ (1 microM - 1 mM, 10 min prior to H(2)O(2)) caused a concentration-dependent inhibition of PARP activity (IC(50): approximately 0.01 mM, n=6). Haemorrhage and resuscitation resulted (within 4 h after resuscitation) in a delayed fall in blood pressure (circulatory failure) as well as in rises in the serum levels of (i) urea and creatinine (renal dysfunction), (ii) aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl-transferase (gamma-GT) (liver injury and dysfunction), (iii) lipase (pancreatic injury) and (iv) creatine kinase (CK) (neuromuscular injury) (n=10). Administration (5 min prior to resuscitation of 5-AIQ) (0.03 mg kg(-1) i.v., n=8, or 0.3 mg kg(-1) i.v., n=10) reduced (in a dose-related fashion) the multiple organ injury and dysfunction, but did not affect the circulatory failure, associated with haemorrhagic shock. Thus, 5-AIQ abolishes the multiple organ injury caused by severe haemorrhage and resuscitation.
...
PMID:Effects of 5-aminoisoquinolinone, a water-soluble, potent inhibitor of the activity of poly (ADP-ribose) polymerase on the organ injury and dysfunction caused by haemorrhagic shock. 1086 91

Acetaminophen (AAP), the analgesic hepatotoxicant, is a powerful inducer of oxidative stress, DNA fragmentation, and apoptosis. The anti-apoptotic oncogene bcl-XL, and the pro-apoptotic oncogene p53 are two key regulators of cell cycle progression and/or apoptosis subsequent to DNA damage in vitro and in vivo. This study investigated the effect of AAP on the expression of these oncogenes and whether agents that modulate DNA fragmentation (chlorpromazine, CPZ) and DNA repair through poly(ADP-Ribose) polymerase (PARP) activity (4-AB: 4-aminobenzamide) can protect against AAP-induced hepatotoxicity by inhibiting oxidative stress, DNA fragmentation, and/or by altering the expression of bcl-XL and p53. In addition, the protective effect of supplemental nicotinamide (NICO), known to be depleted in cells with high PARP activity during DNA repair, is similarly evaluated. Male ICR mice (3 months old) were administered vehicle alone; nontoxic doses of 4-AB (400 mg/kg, ip), NICO (250 mg/kg, ip) or CPZ (25 mg/kg, ip), hepatotoxic dose of AAP alone (500 mg/kg, ip), or AAP plus one of the protective agents 1 h later. All animals were sacrificed 24 h following AAP administration. Serum alanine aminotransferase activity (ALT), hepatic histopathology and lipid peroxidation, DNA damage, and expression of bcl-XL and p53 (western blot analysis) were compared in various groups. All of the three agents significantly prevented AAP-induced liver injury, lipid peroxidation, DNA damage, and associated apoptotic and necrotic cell deaths, 4-AB being the most effective and NICO the least. Compared to control, there was a considerable decrease in bcl-XL expression, and an increase in p53 expression in AAP-exposed livers. The effect of AAP on bcl-XL was antagonized and that on p53 was synergized by the PARP-modulator 4-AB as well as NICO, whereas the endonuclease inhibitor CPZ was without effect on either bcl-XL or p53 expression. These results suggest that the hepatotoxic effect of AAP involves multiple mechanisms including oxidative stress, upregulation of endonuclease (or caspase-activated DNAse) and alteration of pro- and anti-apoptotic oncogenes. The observed antagonism of AAP-induced hepatocellular apoptosis and/or necrosis by modulators of multiple processes including DNA repair suggests the likelihood that a more effective therapy against AAP intoxication should involve a combination of antidotes.
...
PMID:Ca(2+)-calmodulin antagonist chlorpromazine and poly(ADP-ribose) polymerase modulators 4-aminobenzamide and nicotinamide influence hepatic expression of BCL-XL and P53 and protect against acetaminophen-induced programmed and unprogrammed cell death in mice. 1146 65

The use of marginal donor livers is followed by a higher frequency of primary dys- or nonfunction after transplantation. The present study was designed to test the hypothesis that stimulation of the cAMP second-messenger signal pathway might protect the liver from ischemic injury, laying emphasis on the role of protein kinase A-mediated signal transduction. Rat livers were harvested after 45 min of cardiac arrest and preserved in HTK solution for 24 h. Hepatic integrity was assessed thereafter using a blood-free reperfusion model. Supplementation of the preservation solution with dibutyryl-cAMP (db-cAMP) promoted phosphorylation of BAD at Ser 112 and concomitantly mitigated mitochondrial release of cytochrome c into the cytosol. Apoptotic cell transformation was evident in reperfused livers by positive TUNEL-staining of sinusoidal lining cells and the detection of cleaved poly(ADP-ribose) polymerase (PARP) in tissue homogenates by western analysis. Treatment with db-cAMP was effective in minimizing both TUNEL staining and PARP cleavage and significantly reduced postischemic enzyme leakage of alanine aminotransferase to one half, while hepatic bile production was enhanced by approximately 60% when compared to untreated livers. This functional improvement was accompanied by a net amelioration of portal vascular conductivity. Inhibition of A kinase-anchoring protein with HT31 completely reversed any of the observed effects obtained by db-cAMP. We conclude that enhancement of cellular cAMP signal maintains hepatic integrity during and after ischemic preservation which may be attributed to protein kinase A dependent phosphorylation of BAD in line with subsequent inhibition of mitochondria-initiated apoptosis of sinusoidal lining cells.
...
PMID:Significance and molecular targets of protein kinase A during cAMP-mediated protection of cold stored liver grafts. 1170 96

Activation of poly(ADP-ribose) polymerase (PARP) mediates oxidative stress-induced cell injury. We tested the hypothesis that PARP contributes to ischemia-reperfusion (I/R) damage of the liver by triggering the mechanisms of microcirculatory failure. Leukocyte- and platelet-endothelial cell interactions as well as sinusoidal perfusion were analyzed by intravital fluorescence microscopy after lobar hepatic I/R (90 min/30 min) in C57BL/6 x 129/Sv wild-type (PARP+/+) and PARP-deficient (PARP-/-) mice. Hepatic I/R induced leukocyte/platelet-endothelial cell interactions and tissue injury in PARP+/+ mice, as indicated by impaired sinusoidal perfusion and increased alanine aminotransferase (ALT)/aspartate aminotransferase (AST) serum activities. In PARP-/- mice, however, the postischemic increase in the numbers of rolling/adherent leukocytes and platelets was significantly lower. In addition, I/R-induced translocation of CD62P as well as mRNA expression of CD62E, CD54, and CD106 were attenuated. The degree of perfusion failure was reduced and the increase in the ALT/AST activities was lower in PARP-/- mice compared with PARP+/+ mice. We conclude that PARP contributes to hepatic microvascular injury by triggering the expression/translocation of adhesion molecules and modulating leukocyte/platelet-endothelial cell interactions.
...
PMID:Poly(ADP-ribose) polymerase triggers the microvascular mechanisms of hepatic ischemia-reperfusion injury. 1218 Nov 67

DNA fragmentation in hepatocytes occurs early after acetaminophen (AAP) overdose in mice. DNA strandbreaks can induce excessive activation of poly(ADP-ribose) polymerases (PARP), which may lead to oncotic necrosis. Based on controversial findings with chemical PARP inhibitors, the role of PARP-1 activation in AAP hepatotoxicity remains unclear. To investigate PARP-1 activation and evaluate a pathophysiological role of PARP-1, we used both PARP inhibitors (3-aminobenzamide; 5-aminoisoquinolinone) and PARP gene knockout mice (PARP-/-). Treatment of C3Heb/FeJ mice with 300 mg/kg AAP resulted in DNA fragmentation and alanine aminotransferase (ALT) release as early as 3 h, with further increase of these parameters up to 12 h. Few nuclei of hepatocytes stained positive for poly-ADP-ribosylated nuclear proteins (PAR) as indicator for PARP-1 activation at 4.5 h. However, the number of PAR-positive cells and staining intensity increased substantially at 6 and 12 h. Pretreatment with 500 mg/kg 3-aminobenzamide before AAP attenuated hepatic glutathione depletion and completely eliminated DNA fragmentation and liver injury. Delayed treatment several hours after AAP was still partially protective. On the other hand, liver injury was not attenuated in PARP-/- mice compared to wild-type animals. Similarly, the specific PARP-1 inhibitor 5-aminoisoquinolinone (5 mg/kg) was not protective. However, 3-aminobenzamide attenuated liver injury in WT and PARP-/- mice. In summary, PARP-1 activation is a consequence of DNA fragmentation after AAP overdose. However, PARP-1 activation is not a relevant event for AAP-induced oncotic necrosis. The protection of 3-aminobenzamide against AAP-induced liver injury was due to reduced metabolic activation and potentially its antioxidant effect but independent of PARP-1 inhibition.
...
PMID:Pathophysiological role of poly(ADP-ribose) polymerase (PARP) activation during acetaminophen-induced liver cell necrosis in mice. 1560 72

Azidothymidine (AZT) is known to decrease HIV virus replication and is one of the most frequently prescribed antiretroviral drugs used for AIDS treatment. Dose-limiting toxicities are the major curse associated with AZT therapy. Recently, we have reported that tannic acid; a PARG inhibitor prevents cisplatin induced nephrotoxicity. The present work was conceived to study the effect of tannic acid on AZT induced hepatotoxicity and genotoxicity. AZT induces increase in plasma levels of ALT, AST and alkaline phosphatase along with increase in micronucleus (MN) count in peripheral blood. Suggesting, AZT is hepatotoxic and genotoxic to mice. Treatment of tannic acid protects AZT induced hepatotoxicity by decreasing the ALT, AST and alkaline phosphatase levels. It also significantly reduces the oxidative damage by preventing reduction in glutathione and decreasing the level of malondialdehyde in liver of AZT treated mice. In addition, tannic acid decreases the PARG expression, PARP cleavage and histone H3 acetylation in liver of AZT treated mice. Moreover, treatment of tannic acid also decreases MN count in peripheral blood, suggesting its anti-mutagenic effect. In light of these findings we suggest the potential role of tannic acid treatment in preventing AZT induced toxicity.
...
PMID:Tannic acid prevents azidothymidine (AZT) induced hepatotoxicity and genotoxicity along with change in expression of PARG and histone H3 acetylation. 1829 3


1 2 3 4 5 Next >>

---