Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.109 (AST)
 6,066 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary cultures of adult rat hepatocytes were incubated (1.5-16 hr) with various concentrations of CCl4 (less than or equal to 0.5 mM) and/or CHCl3 (less than or equal to 2.5 mM). Agent-dependent alterations in hepatocyte functions were assessed by measuring (1) [3H]choline incorporation into phosphatidylcholine (endoplasmic reticulum), (2) MTT (tetrazolium salt) reduction (mitochondria), and (3) AST release into medium (plasma membrane). Cultured hepatocytes incubated with 0.5 mM CCl4 displayed a significant (p less than or equal to 0.001) and rapid (1.5 hr) reduction (40%) in endoplasmic reticulum function that preceded significant (p less than or equal to 0.001) alterations in mitochondria (6-16 hr) and plasma membrane (6-16 hr) functions. CCl4-dependent alterations in liver cell functions are a result of CCl4 bioactivation since metyrapone inhibits the CCl4-mediated changes in cell functions. Response surface methods (RSM) were used to determine the influence of combinations of CCl4 and CHCl3 on liver cell MTT reduction and [3H]choline incorporation. Regression coefficients were determined for CCl4, CHCl3, and CCl4-CHCl3. All results were significant (p less than 0.0001) and implied that CCl4 was a more potent hepatotoxin in vitro than CHCl3. The RSM analysis also suggested that combinations of CHCl3 and CCl4 have greater than additive effects on MTT reduction and [3H]choline incorporation. These effects of CCl4 and/or CHCl3 on liver cell functions in vitro are consistent with liver alterations observed in vivo. Therefore, primary cultures of adult rat hepatocytes may be an appropriate model in vitro to assess the hepatotoxic potential of agents alone or in combination.
 ...
PMID:Toxic interactions between carbon tetrachloride and chloroform in cultured rat hepatocytes. 279 11

Pravastatin, lovastatin, and simvastatin, drugs which lower cholesterol by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, have been linked to skeletal myopathies in humans and rats. The myotoxicity of these three drugs was compared, after 48 hr exposure, in cultures of primary neonatal rat skeletal myotubes. Measurements included HMG CoA reductase activity ([14C]acetate incorporation into cholesterol), indicators of membrane damage (CPK, LDH, and AST), cell viability (mitochondrial dehydrogenase metabolism of MTT), protein synthesis ([3H]leucine incorporation), and energy status (ATP). All three drugs inhibited cholesterol synthesis to the same extent in rat hepatocytes (IC50s approximately 0.07 microM). Lovastatin- and simvastatin-induced inhibition of cholesterol synthesis in myotubes was unchanged compared to that of hepatocytes, but pravastatin was 85-fold less potent (IC50 = 5.9 microM). Protein synthesis and ATP levels were the most sensitive indicators of toxicity. Pravastatin (IC50 = 759 microM) was > 100-fold less inhibitory of protein synthesis than lovastatin (IC50 = 5.4 microM) or simvastatin (IC50 = 1.9 microM). Addition of mevalonic acid (the immediate product of the HMG CoA reductase reaction), as 100 microM mevalonic acid lactone, reversed the toxicity of all three drugs. Removal of serum for 24-72 hr did not alter the toxicity of any of the drugs compared to cultures containing 10% serum, suggesting that differences in protein binding did not account for the differences in toxicity of the drugs. These results indicate that pravastatin is less myotoxic than lovastatin or simvastatin in this in vitro system using neonatal rat skeletal muscle cells, and this differential toxicity is correlated with the selective decrease in inhibition of HMG CoA reductase by pravastatin in nonhepatic tissues.
 ...
PMID:In vitro myotoxicity of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, pravastatin, lovastatin, and simvastatin, using neonatal rat skeletal myocytes. 787 72

This study reports on measurement of the ethanol-induced hepatotoxicity in vitro on using the human hepatocyte cell line HepG2. Cells were incubated in the presence of increasing ethanol concentrations (10-80 mM). Cytotoxicity was quantitated spectrophotometrically both by the metabolism of the tetrazolium dye MTT and by the release into the medium of LDH and other marker enzymes of ethanol damage (AST, GGT and GHD). No cytotoxicity was observed up to 40 mM ethanol whereas a dose-dependent increment was found at higher concentrations (60-80 mM ethanol). At 80 mM ethanol, cell viability after 24 hours was reduced to 68% and 60% as assessed by MTT and LDH release respectively (p < 0.0001 vs. controls). Exposure for additional 24 hours did not increase cytotoxicity. Transmission electron microscopy revealed the presence of fat droplets (steatosis) and mitochondrial damage. The method reported appears to be an useful and reproducible technique for the in vitro assessment of the ethanol-induced cytotoxicity in a human liver cell line.
 ...
PMID:In vitro assessment of the ethanol-induced hepatotoxicity on HepG2 cell line. 790 31

There is evidence of hepatotoxic effects caused by Perchloroethylene (PCE), presumably due to reactive metabolic intermediates; lipid peroxidation is under study as a potential mechanism of toxicity. We aimed to verify if PCE levels comparable to those reached in the blood of exposed subjects can cause cell damage and lipid peroxidation. The association of PCE with lipid peroxidation inducing drugs (cyclosporine A, valproic acid and amiodarone) was also tested on rat isolated hepatocytes. AST and LDH release, MTT test and lipid peroxidation assay showed that PCE determines dose-dependent effects on rat isolated hepatocytes. The toxic potential resulting from our data would be valproic acid < cyclosporine A < amiodarone. While valproic acid and cyclosporine caused a mild toxicity, the effects of amiodarone were more severe; in particular, the association of PCE with amiodarone showed a clear additive effect. The role of lipid peroxidation in the liver toxicity exerted by the tested compounds was confirmed by our data, and resulted relevant after treatment of cells with amiodarone and PCE. Extrapolating these results to human, we can suggest that a subject professionally exposed to PCE, who chronically assumes a lipid peroxidation inducing drug like amiodarone, may be potentially exposed to a higher risk of liver toxicity.
 ...
PMID:Cytotoxicity evaluation after coexposure to perchloroethylene and selected peroxidant drugs in rat hepatocytes. 1463 60

Cytotoxicity and apoptosis are common problems in the isolation and storage of human hepatocytes. In vitro environments of hepatocytes during cell infusion may be critical to reducing cellular damage and enhancing cell viability. We examined the effects of donor liver histology (40-50% steatosis vs. normal), incubation time, temperature, and three solutions for infusion on banked primary human hepatocytes, by studying: trypan blue exclusion, AST release, LDH release, MTT assay, detection of DNA ladder, and a hepatocyte proliferation assay. In addition, the microstructure functions of the endoplasmic reticulum and mitochondria of the intact hepatocytes were determined by measuring correlates of UGT 1A1 and cytochrome P-450 3A (CYP3A4) activity. In general, hepatocyte viability decreased significantly within 60 min after thawing. Cells suspended in 5% dextrose lactated Ringers solution (D5LR) maintained greater cell viability. Hepatocytes from normal liver donors showed less AST and LDH enzyme leak in comparison with cells from fatty liver donors. Mild hypothermic temperature (32 degrees C) inhibited cellular damage that otherwise significantly increased at 60 min. Hepatocytes did not proliferate until 12 h from thaw, regardless of supernatant or conditions of suspension. CYP3A4 activity and a marker for UGT 1A1 activity in hepatocytes from normal donor livers were higher than those from steatotic donor livers. These findings suggest that hepatocytes suspended for infusion after isolation from normal liver donors have normal biological functions and less cellular damage/necrosis in contrast with those isolated from fatty liver donors. These damages are inhibited significantly by maintaining hepatocytes at a mild hypothermic temperature (32 degrees C). D5LR alone maintained the best cell viability for up to 60 min. Media of D5LR + adenosine and HMM were able to partially inhibit hepatocyte apoptosis in hepatocytes from steatotic livers.
 ...
PMID:Optimization of conditions for clinical human hepatocyte infusion. 1564 38

The determination of a possible corrosive or irritative potential of certain products and ingredients is necessary for their classification and labeling requirements. Reconstructed skin as a model system provides fundamental advantages to single cell culture testing and leads to promising results as shown by different validation studies (for review: Fentem, J.H., Botham, P.A., 2002. ECVAM's activities in validating alternative tests for skin corrosion and irritation. ATLA 30(Suppl. 2), 61-67). In this study we introduce our new reconstructed epidermis "Epidermal-Skin-Test" (EST-1,000). This fully grown epidermis consists of proliferating as well as differentiating keratinocytes. EST-1,000 shows a high comparability to normal human skin as shown by histological and immunohistochemical data. Characteristic markers (KI-67, CK 1/10/5/14, transglutaminase, collagen IV, involucrin, beta 1 integrin) can be identified easily. The main focus of this work was to characterize EST-1,000 especially with respect to its barrier function by testing several substances of known corrosive potential. Skin corrosion was detected by the cytotoxic effect of the substances on a reconstructed epidermis after short-term application to the stratum corneum. The effect was determined by standard MTT assay and accompanying histological analysis. Hence EST-1,000 shows a very high predictive potential and closes the gap between animal testing and the established full-thickness model Advanced-Skin-Test 2,000 (AST-2,000) (Noll, M., Merkle, M.-L., Kandsberger, M., Matthes, T., Fuchs, H., Graeve, T., 1999. Reconstructed human skin (AST-2,000) as a tool for pharmaco-toxicology. ATLA 27, 302).
 ...
PMID:Epidermal-skin-test 1,000 (EST-1,000)--a new reconstructed epidermis for in vitro skin corrosivity testing. 1606 50

Primary cultures of rat hepatocyte and rats were used as the in vitro and in vivo models to evaluate the hepatoprotective activity of aqueous extract from Thunbergia laurifolia (TLE). Ethanol was selected as hepatotoxin. Silymarin (SL) was the reference hepatoprotective agent. In the in vitro study, MTT reduction assay and release of transaminases (ALT and AST) were the criteria for cell viability. Primary cultures of rat hepatocyte (24 h culturing) were treated with ethanol (96 microl/ml) and various concentrations of TLE (2.5, 5.0, 7.5 and 10.0 mg/ml) or SL (1, 2 and 3 mg/ml) for 2 h. Ethanol decreased MTT (%) nearly by half. Both TLE and SL increased MTT reduction and brought MTT (%) back to normal. Ethanol induced release of ALT and AST was also reduced by TLE (2.5 and 5.0 mg/ml) and SL (1 mg/ml). In the in vivo study, serum transaminases, serum triglyceride (STg) together with hepatic triglyceride (HTg) and histopathological examination were the criteria for evidences of liver injury. Ethanol (4 g/(kg day), po for 14 days) caused the increase in ALT, AST, HTg and centrilobular hydropic degeneration of hepatocytes. TLE at 25 mg/(kg day), po, or SL at 5 mg/(kg day), po, for 7 days after ethanol enhanced liver cell recovery by bringing HTg, ALT and/or AST back to normal. These results suggest that TLE and SL possess the hepatoprotective activity against ethanol induced liver injury in both primary cultures of rat hepatocyte and rats.
 ...
PMID:Hepatoprotective activity of Thunbergia laurifolia Linn extract in rats treated with ethanol: in vitro and in vivo studies. 1608 78

This study was undertaken to investigate the protective effects of Phyllanthus emblica Linn. (PE) extract on ethanol induced rat hepatic injury. PE (0.5 and 1 mg/ml) increased cell viability of rat primary cultured hepatocytes being treated with ethanol (96 microl/m) by increasing % MTT and decreasing the release of transaminase. Hepatotoxic markers studied in rats included serum transaminases (AST and ALT), serum triglyceride (STG), hepatic triglyceride (HTG), TNF-alpha and IL-1beta together with histopathological examination. Pretreatment of rats with PE at oral dose of 25, 50 and 75 mg/kg or SL (silymarin, a reference hepatoprotective agent) at 5 mg/kg, 4 h before ethanol, lowered the ethanol induced levels of AST, ALT and IL-1beta. The 75 mg/kg PE dose gave the best result similar to SL. Treatment of rats with PE (75 mg/kg/day) or SL (5 mg/kg/day) for 7 days after 21 days with ethanol (4 g/kg/day, p.o.) enhanced liver cell recovery by bringing the levels of AST, ALT, IL-1beta back to normal. Histopathological studies confirmed the beneficial roles of PE and SL against ethanol induced liver injury in rats.
 ...
PMID:The protective effects of Phyllanthus emblica Linn. extract on ethanol induced rat hepatic injury. 1675 Mar 40

This work is an experimental response to an intriguing paper recently published by Catlow and co-workers, which looked at the computational feasibility of fluorine location in three different all-silica zeotypes (Attfield, M. P.; Catlow, C. R. A.; Sokol, A. A. Chem. Mater. 2001, 13, 4708). The materials were chosen as representative of three unique host locations. Our present work examined the synthesis of zeotypes AST, IFR, and MTT using organo-cations with a strong preference for crystallizing these structures. We studied the effect of reaction time and the H(2)O/SiO(2) reactant ratio. The latter is probably the most important function in these zeolite crystallizations that use HF. As reaction conditions became more dilute, AST gave way to SGT and IFR to MTW as host structures, while the MTT synthesis was invariant. Our reactions were studied in terms of product yield vs time, product organo-cation content, fluorine content, and the representative (29)Si and (19)F NMR spectra for certain samples. A single crystal study was carried out for a sample of MTT. Our results showed that, consistent with other recent studies, low H(2)O/SiO(2) reactant ratios lead to more open framework host structures (i.e., IFR vs MTW), and there is typically a higher uptake of organo-cation and fluorine. The structure may well contain a higher population of 4-rings within the silicate substructure. While MTT that contains no 4-rings was chosen as the best possible candidate to achieve an ion-pair for the organo-cation and fluoride anion within the silicate host, both NMR and single crystal work confirm that fluoride is bonded to a 5-coordinate silica center within the lattice.
 ...
PMID:Studies on the role of fluoride ion vs reaction concentration in zeolite synthesis. 1685 Oct 58

This study is to observe the protection of gross saponins of Tribulus terrestris (GSTT) on cardiocytes impaired by adriamycin (ADR) and approach its mechanism of action. Cardiocytes of neonate rat were cultivated for 72 hours and divided into normal control group, model (ADR 2 mg x L(-1)) group, and GSTT (100, 30, and 10 mg x L(-1)) groups. MTT colorimetric method was deployed to detect cardiocyte survival rate, activities of CK, LDH, AST, SOD, MDA and NO were detected, and apoptosis was detected with flow cytometry. Effect of GSTT on caspase-3 was detected with Western blotting. Compared with control group, contents of CK, LDH, AST, MDA and NO were increased, and activity of SOD was reduced (P < 0.05, P < 0.01, P < 0.001) by ADR. Numbers of survival cells were increased (P < 0.05, P < 0.001), contents of CK, LDH, AST, MDA and NO were decreased, and activity of SOD was increased (P < 0.05, P < 0.01, P < 0.001) by GSTT (100 and 30 mg x L(-1)). Apoptosis of cardiocytes and concentration of caspase-3 can be reduced by GSTT (100 and 30 mg x L(-1)). GSTT can protect cardiocytes impaired by ADR, which are possible involved with its effect of resisting oxygen free radical.
 ...
PMID:[Effect of gross saponins of Tribulus terrestris on cardiocytes impaired by adriamycin]. 2135 46


1 2 3 4 Next >>