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S Awasthi

Publications and source records attributed to S Awasthi.

At least 109 records · Page 6Linked to original sources
PubMed1993

Purification and characterization of glutathione S-transferase of murine ovary and testis.

Recent studies have indicated that sex hormones may regulate expression of murine glutathione S-transferase (GST) isozymes. Therefore, we have purified and compared GST isozymes of murine ovary and testis, two tissues with markedly different hormonal milieu. Isoelectric profiles of the GST isozymes of both these tissues were found to be closely similar. Both expressed one alpha-class GST (pI9.8), one pi-class GST (pI8.9), and three mu-class GSTs (pI8.5, 7.9, and 6.7). In addition, an isozyme (pI5.8) corresponding to the rat GST 8-8 was also expressed in both these tissues. Total GST protein/g tissue was about 1.7-fold more abundant in testis. The specific activities of the cationic isozymes of testis were 1.2- to 2.4-fold higher as compared to those of ovaries. On the other hand, the specific activities of the anionic testicular isozymes were 6.4- to 10-fold higher compared to the corresponding ovarian isozymes. Structural properties including the N-terminal sequences of the testicular isozymes were indistinguishable from those of their ovarian counterparts. The N-terminal sequence of the pi-class GST of both tissues was similar to that of mouse liver GST pi. The three mu-class GSTs of testis and ovary arise from the dimeric combinations of two subunits whose N-terminal sequences determined up to 24 residues were similar to those of mouse liver GST subunits mu 1 and mu 2. Although testicular and ovarian isozymes were structurally similar, Kcat values of some of the testicular isozymes were up to 10-fold higher than those of the corresponding ovarian isozymes. The substrate specificities were also significantly different for the corresponding isozymes of testis and ovary.

Amino Acid Sequence↗
PubMed1993

Semicarbazide protection from in vivo oxidant injury of vascular tissue by allylamine.

Allylamine is a specific cardiovascular toxin that causes vascular and myocardial lesions. Previous studies showed that allylamine-induced chronic lesions are markedly reduced by semicarbazide, an inhibitor of semicarbazide-sensitive amine oxidase (SSAO), and that allylamine is metabolized to the aldehyde, acrolein, by SSAO. We hypothesized that inhibitors of SSAO might reduce the acute cardiovascular toxicity of allylamine. To test our hypothesis, we fed 150 mg/kg allylamine to semicarbazide-pretreated (3 h; 98 mg/kg) rats. Animals were sacrificed 1 h after allylamine treatment. Aorta, epicardium, and endocardium were assayed for SSAO, glutathione peroxidase, catalase, thiol status and lipid peroxidation. SSAO activity was decreased significantly in aorta, epicardium and endocardium. Activity was 30-times higher in aorta than in epicardium and endocardium. A striking decrease in malonaldehyde level (lipid peroxidation) was found in aorta of pretreated rats as compared to allylamine-only treated rats. The reduction of free-SH content in aortic mitochondria was also attenuated in pretreated rats. Changes were not so marked in epicardium and endocardium. These results suggest that in vivo pretreatment with semicarbazide at least partially protects aortic mitochondria from allylamine toxicity. The mechanism can be explained on the basis of the fact that semicarbazide inhibits acrolein formation in allylamine-treated rats.

Allylamine↗
PubMed1992

Reversed-phase chromatographic method for specific determination of glutathione in cultured malignant cells.

A chromatographic method for the specific determination of glutathione in malignant cell lines is described. The method is based on the ability of glutathione-S-transferase to specifically and quantitatively conjugate glutathione to 1-chloro-2,4-dinitrobenzene and chromatographic quantitation of the resultant conjugate, dinitrophenyl-S-glutathione, by reversed-phase liquid chromatography. The assay can be performed on 20,000 g supernatants of cell homogenates without acid extraction. 2-Mercaptoethanol, a sulfhydryl compound often used as a thiol-protective agent to preserve enzymatic activities of a number of enzymes, did not interfere with glutathione determination by this method. The dinitrophenyl-S-glutathione isolated from either standard glutathione samples or from cell homogenates was shown to be identical to authentic dinitrophenyl-S-glutathione using mass spectrometry. Recovery of glutathione in standard samples by the current method was identical to that determined using 5,5'-dithiobis(2-nitrobenzoic acid). Exogenous glutathione added to supernatants of cell homogenate in the presence or absence of 2-mercaptoethanol was also completely recovered.

Chromatography, High Pressure Liquid↗
PubMed1992

Gender related differences in the expression and characteristics of glutathione S-transferases of human colon.

In the present study, the expression of glutathione S-transferase (GST) isozymes was compared in human male and female colon tissues. GST isozymes were purified and quantified in five male and five female colon tissue samples. Noticeable differences were observed in the isoelectric focusing profiles (IEF) of the GSTs, from male and female colon tissues. Both male and female colon tissues had three common GST peaks with pI values of 9.2, 6.7 and 4.8. An additional GST peak with a pI value of 6.2 found in all females was not found in males. Based on kinetic, immunological and structural properties, these isozymes were classified into alpha (pI 9.2), mu (pI 6.7 and 6.2) and pi (pI 4.8) classes. Activity of the alpha-class GST in male colon was approx. 2-fold higher than the corresponding isozyme in female colon. The pi-class GST 4.8 was the most predominant GST in both the sexes and its activity with CDNB as substrate was more abundant (about 1.6-fold) in female colon as compared to that in male colon. Significant differences were seen in substrate specificities between male and female colon GST 4.8. Sex related differences were also observed in the inhibition kinetics of GST pi from male and female colon in the presence of hematin. In addition, GST pi isolated from female colon was more thermostable as compared to the corresponding male isozyme. The thermostability of purified GST pi isozyme from males or females was not affected by incubation of the enzyme with either estrogen, testosterone or progesterone.

Amino Acid Sequence↗
PubMed1992

The relationship of doxorubicin binding to membrane lipids with drug resistance.

Doxorubicin (DOX, Adriamycin) binds with high affinity to cellular membranes inflicting multiple lesions which are believed to be important in DOX-mediated neoplastic cell death. Using fluorescence and radioactive [14-14C-14]DOX assays for DOX, we have measured the partitioning of DOX between the cytosolic and membrane fractions of erythrocytes and of DOX-sensitive (V-79) and -resistant (LZ) Chinese hamster lung fibroblast cells. In both erythrocytes and fibroblasts, a significant fraction of DOX was associated with the membrane fraction. More significantly, the quantity of lipid-bound DOX in the fibroblasts correlated with the cell's susceptibility to DOX. The significance of these findings in the context of existing knowledge about DOX-membrane interactions is discussed.

Animals↗
PubMed1992

Oxidative changes in brain of aniline-exposed rats.

Oxidative stress in rat cerebellum, cortex and brain stem after a short-term high-dose exposure to aniline vapors under conditions akin to those after major chemical accidents, was studied. Significant increases in superoxide dismutase isozyme activities and formation of thiobarbituric acid reactive material along with depletion of ascorbic acid and non-protein sulfhydryl content suggest impairment of antioxidant defenses 24 h after single exposure to 15,302 ppm aniline vapors for 10 min.

Aniline Compounds↗
PubMed1992

Dinitrophenyl S-glutathione ATPase purified from human muscle catalyzes ATP hydrolysis in the presence of leukotrienes.

Dinitrophenyl S-glutathione (Dnp-SG) ATPase has been purified from human muscle to apparent homogeneity using Dnp-SG affinity chromatography and immunoaffinity chromatography using antibodies raised against human erythrocyte Dnp-SG ATPase. The enzyme purified from human muscle showed a subunit M(r) value of about 38 kDa in denaturing gels. The M(r) value of the native enzyme as determined by Sephadex G-200 gel filtration was found to be about 80 kDa, which indicates that it is a dimer. The N-terminus of the enzyme was blocked. Its immunological and kinetic properties were similar to Dnp-SG ATPase of human erythrocytes. Besides catalyzing the ATP hydrolysis in the presence of Dnp-SG, the muscle enzyme also catalyzed ATP hydrolysis in the presence of various leukotrienes, namely LTC4.LTD4, LTE4, and N-acetyl LTE4. The specific activity of the enzyme toward LTC4 was relatively higher than other GSH-xenobiotic conjugates. The muscle enzyme exhibits a low Km value for all leukotrienes as compared to Dnp-SG, indicating high affinity of the enzyme for leukotrienes as activators. The enzyme also catalyzed ATP hydrolysis in the presence of GSH conjugates of endogenously generated fatty acid epoxides. Our results might suggest that Dnp-SG ATPase is involved in the transport of GSH conjugates, leukotrienes, and other organic anions in muscle, erythrocytes, liver, and probably other tissues.

Adenosine Triphosphatases↗
PubMed1992

Glutathione S-transferases of human lung: characterization and evaluation of the protective role of the alpha-class isozymes against lipid peroxidation.

Glutathione S-transferase (GST) isozymes of human lung have been purified, characterized, quantitated, and, based on their structural and immunological profiles, identified with their respective classes. The tau-, mu-, and alpha-class GSTs represented 94, 3, and 3% activities of total human lung GSTs toward CDNB, respectively, and 60, 10, and 30% of total GST protein, respectively. Both the mu- and the alpha-class GSTs of human lung exhibited heterogeneity. The two mu-class GSTs of human lung had pI values of 6.5 and 6.25 and were differentially expressed in humans. Significant differences were seen between the kinetic properties of these two isozymes and also between the lung and liver mu-class GSTs. The alpha-class GST isozymes of lung resolved into three peaks during isoelectric focusing corresponding to pI values of 9.2, 8.95, and 8.8. All three alpha-class GSTs isozymes had blocked N-termini and were immunologically similar to human liver alpha-class GSTs. Peptide fingerprints generated by SV-8 protease digestion and CNBr cleavage indicated minor structural differences between the liver and the lung alpha-class GSTs. The three alpha-class GSTs of lung expressed glutathione peroxidase activities toward the hydroperoxides of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol, with Km values in the range of 22 to 87 microM and Vmax values in the range of 67-120 mol/mol/min, indicating the involvement of the alpha-class GSTs in the protection mechanisms against peroxidation. All three classes of lung GSTs expressed activities toward leukotriene A4 methyl ester and epoxy stearic acid but the mu-class GSTs had relatively higher activities toward these substrates.

Blotting, Western↗
PubMed1991

Agenesis of the gallbladder--a case report.

Agenesis of the gallbladder, which is an extremely rare anomaly, may present with biliary symptoms but is virtually impossible to diagnose by such conventional investigations as oral cholecystogram or ultrasonography. We report herein a case of a young man presenting with episodic epigastric pain on whom an ultrasonographic diagnosis of gallstones was made. A gallbladder was not visualized on oral cholecystogram, however, he was subsequently found to have agenesis of the gallbladder, the diagnosis of which was confirmed by intra-operative cholangiography and a postoperative N-2,6-dimethylphenylcarbamoyle methyl iminodiacetic acid scan (HIDA scan). His symptoms responded to antiulcer treatment with upper gastrointestinal endoscopic findings suggestive of oesophagitis and duodenitis.

Adolescent↗
PubMed1991

Increase in lysolecithin content of brain microsomes in phenobarbitone-administered rats and its relation to lipid peroxidation.

Administration of phenobarbitone caused a marked increase in the capacity of rat brain microsomes to produce thiobarbituric acid-reactive substances in vitro. Enzymatic peroxidation of lipids was more affected than the nonenzymatic processes occurring in heat-inactivated preparations. Analysis of the phospholipid profile showed a drastic decrease in phosphatidylcholine and total phospholipid contents in the exposed animals, but about a fivefold increase in the lysophosphatidylcholine fraction. Data for in vivo incorporation of [14C]choline showed a similar pattern of high radioactivity in lysolecithin. The increase in lipid peroxidation could be related to the higher level of lysolecithin and the accompanying structural and functional changes in microsomes resulting from the neurotoxic effects of phenobarbitone.

Animals↗
PubMed1991

Mortality patterns in breast versus artificially fed term babies in early infancy: a longitudinal study.

The present study comprised 381 term babies weighing greater than 2.5 kg and 126 babies weighing less than or equal to 2.5 kg (low birth weight; LBW) at birth. A longitudinal follow up of 334 babies was done for 6 months. There were 273 'breast fed' babies and 234 'artificially fed' babies. Neonatal mortality rate per 1000 live births for term babies was 37.5, LBW had a rate of 31.5 while those weighing greater than 2.5 kg at birth a rate of 5.9; artificially fed had a mortality rate of 21.6 while breast fed had a low rate of 15.8. For 1-6 months period a mortality rate per 1000 live births of 53.8 was found for term babies, breast fed a rate of 23.9 while artificially fed a rate of 29.9; LBW had a rate of 44.9 while those weighing more than 2.5 kg at birth, a rate of 9. Low birth weight babies whether breast fed or artificially fed had significantly higher mortality than similarly fed babies weighing more than 2.5 kg at birth. Hence, mortality rate for term babies in early infancy can be reduced by simultaneous promotion of breastfeeding and prevention of low birth weight as it was dependent on both variables in this study.

Breast Feeding↗
PubMed1989

Effect of anaesthetic ether on lipid peroxidation and superoxide dismutase isozymes of young and adult rat brain.

Changes in lipid peroxidation and superoxide dismutase level in rat brain due to single exposure to diethyl ether (anaesthetic) were studied in 100 and 300 day old rats. Enhancement of superoxide dismutase activity was more pronounced in young rat brain, while the reverse was the case with lipid peroxidation. The neurotoxic effects of diethyl ether may involve active oxygen species and superoxide dismutase activity increases as a defensive adaptation.

Animals↗
PubMed1989

Simple hematological tests for diagnosis of neonatal sepsis.

Simple hematological tests, TLC, DLC, mESR, platelet count, were performed in 128 neonates of which 50 were controls and 78 were cases of suspected septicemia. Thirty three had positive blood cultures and were taken as 'proved' and remaining as 'probable' sepsis. A band cell neutrophil (B/N) ratio of greater than 0.2 was most sensitive index (92%) followed by raised mESR of greater than 8 mm for 1st hour, whereas leukopenia of greater than 5 x 10(3)/mm3 was most specific index (88%) for the diagnosis of sepsis. Thrombocytopenia of less than 1.5 x 10(5)/cu mm was also taken as positive test for sepsis. A combination of three positive tests had highest positive predictive accuracy (94%) for early diagnosis of sepsis, when compared to single test or two positive test combinations. The best combination of tests was B/N ratio, leukopenia and mESR which can be easily done in a side laboratory.

Blood Sedimentation↗
PubMed1989

Is high protein milk beneficial for SGA-terms?

A three months longitudinal followup of SGA term babies was done for their response to feeding of high protein milk (3.1 g/100 ml) and they were compared with their breast fed counterparts. The formula fed infants had no advantage over the breast fed when weight was compared. However, blood urea and serum creatinine levels were higher in the formula fed infants, than the breast fed ones. The serum valine concentrations, indicative of protein nutritional status, increased with increasing postnatal age in all the infants. Formula fed had higher serum valine than breast fed ones. Serum phenylalanine and serum tyrosine levels, which may hamper CNS development, were higher in the formula fed infants than the breast fed ones.

Follow-Up Studies↗