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Biomedical subjects

S Awasthi

Publications and source records attributed to S Awasthi.

At least 73 records · Page 4Linked to original sources
PubMed1997

Rat GST 8-8 is expressed predominantly in myeloid origin cells infiltrating the gravid uterus.

Previous studies from our laboratory have shown a relatively high expression of rGST8-8 in uterine tissues. This GST isozyme displays relatively high glutathione-peroxidase activity towards lipid-hydroperoxides and towards toxic 4-hydroxyalkenals generated from lipid peroxidation. Since the uterus is a unique organ, subject to oxidative stress due to infiltration by immune effector cells during gestation and because this infiltration is readily identifiable histologically, the studies reported herein were performed to localize the cell specific expression of rGST8-8 to determine whether immune effector cells infiltrating the pregnant rat uterus specifically expressed rGST8-8. A 75 bp end-radiolabeled cRNA probe was prepared from the full length mGSTA4-4 cDNA from the region which is highly homologous with rGST8-8. This cRNA probe was used for in situ hybridization studies to localize rGST8-8 in specific cell types of gravid rat uterus. Results of these studies indicate that this GST isozyme is selectively expressed in myeloid origin cells such as monocytes/macrophages, and neutrophils infiltrating the uterine endometrium and in vascular walls. Selective expression of rGST8-8 in the myeloid origin cells, which are known to generate higher levels of reactive oxygen species, suggests that this GST isozyme plays an important role in the protection mechanisms against lipid peroxidation.

Animals↗
PubMed1997

Differential carcinogenicity of benzo[a]pyrene in male and female CD-1 mouse lung.

Benzo[a]pyrene (BaP) is known to induce tumors in lung, forestomach, and skin in experimental animals. Earlier studies have suggested that glutathione S-transferase pi (GST pi) is involved in the detoxification of the "ultimate" carcinogenic metabolite of BaP, 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). The constitutive expression of GST pi in the liver of the male CD-1 mouse is higher than that of the female, and BHA has been shown to preferentially induce GST pi in the female as compared with the male mouse. The present studies were therefore designed to compare the susceptibility of male and female CD-1 mice to the carcinogenic effects of BaP and the protective effect of BHA. Results of these studies show that the female CD-1 mice are more susceptibile to the carcinogenic effect of BaP than the males and that the attenuation of BaP-induced carcinogenesis by BHA appears to be restricted only to the females.

Adenocarcinoma↗
PubMed1997

Prevalence of malnutrition and intestinal parasites in preschool slum children in Lucknow.

OBJECTIVE: To assess the point prevalence of intestinal parasites and their association with nutritional parameters. SETTING: Anganwadi centers under the Integrated Child Development Scheme (ICDS) in Lucknow, North India. DESIGN: Cross-sectional survey. METHODS: By random draw, 32 out of 153 Anganwadi centers were selected. All eligible subjects registered with the Anganwadi worker were enrolled. These were 1061 children (48.3% girls and 51.7% boys) between the ages of 1.5 to 3.5 years. RESULTS: Of these, 67.6% were underweight (weight for age < -2 SD), 62.8% were stunted (height for age < -2 SD) and 26.5% were wasted (weight for height < -2 SD). Parasites were detected in 17.5% (95% CI 15.3%-19.9%) children by a single direct fecal smear examination. Of these, Ascaris lumbricoides was found in 124 (68.1%) and Giardia lamblia in 60 (32.9%). There was no association between weight or height and parasite positivity. The mean hemoglobin levels for children who were smear positive versus smear negative for ascaris or giardia were 9.1 g/dl and 9.6 g/dl, respectively (p < 0.0001). CONCLUSION: In the urban slums the point prevalence of intestinal parasites is 17.5% in the preschool children. Malnutrition and low hemoglobin levels are also widely prevalent. Urgent remedial steps are needed on community basis to improve their nutritional status and control parasitic infestation.

Animals↗
PubMed1997

Cardiovascular responses to treadmill exercise testing in anemia.

OBJECTIVE: To study exercise performance on a treadmill in anemic children. DESIGN: Prospective case control study. SETTING: Department of Pediatrics and Intensive Care Unit, Department of Medicine, King George's Medical College, Lucknow. SUBJECTS: The study population consisted of 41 cases of anemia (10 mild, 21 moderate and 10 severe) and 11 normal age and height matched children aged between 7-12 years. METHODS: These subjects were exercise tested on Quinton Model Q5000 treadmill using Modified Naughton Q5000 protocol. Heart rate, systolic blood pressure, double product, ECG changes, exercise duration and metabolic equivalents achieved during peak exercise were studied. Statistical analysis was performed using analysis of variance (ANOVA) test. RESULTS: No significant difference was observed in values of resting heart rate, heart rate at peak exercise, recovery heart rate, blood pressure response, resting double product, double product at peak exercise, recovery double product and ECG changes in any of the study groups (p > 0.05). However, the gain in heart rate at peak exercise compared to basal value, and double product, total exercise duration and metabolic equivalent (MET) values at peak exercise were significantly low in anemic children on comparison to normal controls (p < 0.001). CONCLUSIONS: Cardiovascular responses are blunted in anemia, mainly because of depleted cardiac reserve.

Analysis of Variance↗
PubMed1997

Seasonal pattern of morbidities in preschool slum children in Lucknow, north India.

OBJECTIVE: To quantify the burden of common morbidities for each month in one year, in preschool children. SETTING: Anganwadi centers under the Integrated Child Development Services Scheme (ICDS) in Lucknow, North India. DESIGN: Prospective cohort study, METHODS: From 153 anganwadi centers in urban Lucknow, 32 were selected by random draw. All eligible children registered with the anganwadi worker were enrolled over a period of six months from July 1995 to January 1996. All the subjects were then contacted a second time six months later. SUBJECTS: There were 1061 children (48.3% girls and 51.7% boys) between the ages of 1.5 to 3.5 years. RESULTS: The annual incidence rate (IR) per 100 child-years for respiratory, diarrhea and skin diseases and pneumonia were 167, 79.9, 30.6 and 9.6, respectively. When compared to other seasons, the IR of pneumonia was lowest in the winter months (October to February) while those of diarrhea and skin diseases were the highest in summer (March-June) and monsoon (July to September) months, respectively. Season specific diseases were measles in summer, and fever as the isolated symptom in monsoon. The IR for combined morbidities was the highest in the monsoon as compared to winter months. CONCLUSIONS: Season specific intensification of existing health care resources for these morbidities can be considered. Similar studies are needed from other parts of the country.

Child, Preschool↗
PubMed1996

Purification and characterization of a 4-hydroxynonenal metabolizing glutathione S-transferase isozyme from bovine pulmonary microvessel endothelial cells.

Previous studies have suggested that a group of structurally and immunologically related mammalian glutathione S-transferases (GSTs) which utilize 4-hydroxynonenal (4-HNE) as the preferred substrate and show glutathione peroxidase activity towards phospholipid hydroperoxides may be important for the defense of cells against lipid peroxidation. In present studies we have purified and characterized GST isozymes of bovine pulmonary microvessel endothelial (BPMVE) cells. The results of these studies indicate that BPMVE cells express relatively high amounts of a GST isozyme which utilizes 4-HNE as the preferred substrate. This GST isozyme purified to homogeneity from BPMVE cells showed remarkably high specific activity towards 4-HNE (48.3 units/mg protein) and had similar immunological, kinetic, and structural characteristics as reported for mouse enzyme mGSTA4-4 and other mammalian GSTs of this group. Since the endothelial cells are exposed to constant oxidative stress, we suggest that this GST isozyme may be important for the defense of these cells against lipid peroxidation.

Aldehydes↗
PubMed1996

Modulation of doxorubicin cytotoxicity by ethacrynic acid.

Energy-dependent membrane efflux pumps have been implicated in mediating resistance to doxorubicin (DOX). Membrane-transport mechanisms distinct from P-glycoprotein, capable of transporting DOX and glutathione conjugates have been reported in human cells. Since glutathione-conjugate-forming compounds may be candidates for modulating the cytotoxicity of certain anti-neoplastic agents transported by such transport mechanism, the present studies were performed (i) to determine whether ethacrynic acid, a glutathione-conjugate-forming diuretic, can increase DOX cytotoxicity, and (ii) to study the kinetics of DOX transport and its inhibition by the glutathione conjugate of ethacrynic acid (EA-SG) in the H69 human small-cell-lung-cancer cell line and 2 derived DOX-resistant sublines. Our results indicate that more than one DOX transport mechanism may exist in these cell lines, and that glutathione conjugates may be useful for modulating the cytotoxic effects of DOX.

ATP-Binding Cassette Transporters↗
PubMed1996

Transfection of a 4-hydroxynonenal metabolizing glutathione S-transferase isozyme, mouse GSTA4-4, confers doxorubicin resistance to Chinese hamster ovary cells.

It has previously been suggested that adriamycin (doxorubicin, DOX), which is used to treat various types of malignancies, exerts its cytotoxic effects through interactions with DNA and by accelerating membrane lipid peroxidation. Our previous studies have indicated that a mouse glutathione S-transferases isozyme, mGSTA4-4, which shows high activity toward 4-hydroxyalkenals and the hydroperoxides formed during lipid peroxidation, may play an important role in defense mechanism against lipid peroxidation. In order to test the hypothesis that the enhanced protection against lipid peroxidation confers DOX-resistance to cells, we have compared the cytotoxicity of DOX to Chinese hamster ovary cells transfected with mGSTA4-4 with that of controls cells transfected with the vector alone. The results of these studies show that mGSTA4-4-transfected cells have a twofold higher resistance to DOX as compared to the controls. Upon exposure to DOX, the transfected cells showed about 40% less membrane lipid peroxidation as compared to the controls, indicating a positive relationship between DOX-cytotoxicity and lipid peroxidation. These results suggest that mGSTA4-4 provides protection to cells against lipid peroxidation and that DOX cytotoxicity, at least in part, is mediated through oxidative stress resulting in peroxidation of membrane lipids which would explain the results of previous studies showing that DOX can kill cells without being internalized (T.R. Tritton and G. Yee (1982) Science 217, 248-250).

Aldehydes↗
PubMed1996

A glutathione S-transferases isozyme (bGST 5.8) involved in the metabolism of 4-hydroxy-2-trans-nonenal is localized in bovine lens epithelium.

Previous studies have suggested that a group of GST isozymes (bGST 5.8) with substrate preference for 4-hydroxy-2-trans-nonenal (4-HNE) were present in bovine retina, cornea, iris-ciliary body and sclera, but not in lens. The present studies demonstrate that bGST 5.8 is present in bovine lens epithelium and absent in the cortex and nucleus. Immunochemical studies demonstrated that the enzyme is selectively expressed in epithelium where it can be induced by about 2.5-fold when the lenses are cultured in Medium-199 for 24 hr in the presence of 10 microM BHT. bGST 5.8 was purified to homogeneity from the epithelium using immunoaffinity chromatography. Upon SDS-PAGE, the enzyme showed a single band corresponding to an M(r) value of 25 kDa and its CNBr-peptide maps in SDS-gels were identical to those of the isozymes of this group of GSTs reported previously. The enzyme exhibited high activity towards 4-HNE, and showed glutathione peroxidase activity towards phospholipid hydroperoxides. The Km values of the enzyme for 4-HNE (57 microM from control and 52 microM from BHT-treated) were in the same range as those reported for GSTs 5.8 of human ocular tissues. However, the Kcat value of the lens epithelium enzyme for 4-HNE (15.4 mol mol-1 sec-1 from control, and 20.2 mol mol-1 sec-1 from BHT treated) were considerably less than those reported for the human ocular GST 5.8. Results of these studies suggested that a GST isozyme involved in the detoxification of the electrophilic products of lipid peroxidation was localized in the epithelium of bovine lens.

Aldehydes↗
PubMed1996

Rabbit aorta glutathione S-transferases and their role in bioactivation of trinitroglycerin.

The pharmacological action of glyceryl trinitrate (GTN), a widely used drug for the treatment of angina pectoris, is thought to be mediated through release of nitric oxide (NO) during its biotransformation. Since glutathione S-transferases (GST) can utilize GTN as substrate and GST inhibitors can attenuate GTN-induced relaxation of rabbit aorta in vitro it has been suggested that these enzymes are involved in the bioactivation of GTN in rabbit aorta. Because GSTs are multifunctional enzymes and a multitude of GST isozymes with varying substrate preferences are present in mammalian tissues, the role of specific GST isozymes in bioactivation of GTN in rabbit aorta needs to be established. Therefore, during the present studies we have purified and characterized GST isozymes from rabbit aorta and evaluated their possible roles in the biotransformation of GTN. The results of these studies showed that rabbit aorta contained three GST isozymes having pI values of 9.4, 7.7, and 5.4. Structural, immunological, and kinetic studies showed that GST 9.4, GST 7.7, and GST 5.4 belonged to the alpha-, pi-, and mu-classes, respectively. The relative abundance of these enzymes in rabbit aorta was alpha > pi > mu. The alpha- and mu-class GST isozymes had similar activities toward GTN (0.71 U/mg and 0.86 U/mg, respectively) while the pi-class GST showed much lower activity toward GTN. The catalytic efficiency k(cat)/Km of the mu- and alpha-class GSTs toward GTN were similar but these activities were differentially inhibited by ethacrynic acid, its GSH conjugate, bromosulfophthalein (BSP), and hematin. These results suggest that in rabbit aorta GSTs may be involved in bioactivation of GTN, and because of their higher abundance the alpha-class GSTs may be more important for the pharmacological effects of GTN than the mu-class GSTs. The results on kinetics of inhibition by various inhibitors suggest that hematin may be an effective inhibitor to delineate the role of specific GST isozymes in the bioactivation of GTN.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of glutathione S-transferases of rat uterus.

Glutathione S-transferases (GSTs) provide protection to cells against electrophilic xenobiotics as well as lipid hydroperoxides and 4-hydroxynonenal generated during lipid peroxidation. The catalytic properties of the alpha class GSTs are well suited for detoxification of electrophilic products of lipid peroxidation. An immunologically distinct subgroup of the alpha class GST isozymes having high activity towards 4-hydroxynonenal has been recently identified in several mammalian tissues [Zimniak et al. (1994) J. Biol. Chem. 269, 992-1000]. Since oxidative stress can exert deleterious effects during gestation, the present studies were performed to determine whether the rat homolog of this group of GSTs, rGST 8-8, is expressed in gravid rat uterus, where it may function as a defense mechanism against oxidative stress. GSTs were purified by GSH-affinity chromatography. Individual GST isozymes were separated by column isoelectric focusing and their immunologic identities were established using highly specific polyclonal antibodies in Western blot analysis. Their expression was quantified and kinetic properties were characterized. Rat uterus contained an alpha class GST (pI 9.8), a pi class GST (pI 8.1), two mu class GSTs (pI 6.7 and 6.2) and rGST 8-8. This result indicated that rGST subunits 1, 2, 3, 4, 7 and 8 are present in rat uterus. The relative abundance of rGST 8-8 in the gravid rat uterus was found to be about three-fold higher as compared with that previously seen in rat liver. Higher relative abundance of rGST8-8 in gravid rat uterus suggests that it may play a protective role against the deleterious effects of lipid peroxidation during gestation.

Amino Acid Sequence↗
PubMed1996

Curcumin protects against 4-hydroxy-2-trans-nonenal-induced cataract formation in rat lenses.

Age-related cataractogenesis is a significant health problem worldwide. Oxidative stress has been suggested to be a common underlying mechanism of cataractogenesis, and augmentation of the antioxidant defenses of the ocular lens has been shown to prevent or delay cataractogenesis. The present studies were designed to test the efficacy of curcumin, an antioxidant present in the commonly used spice turmeric, in preventing cataractogenesis in an in vitro rat model. Rats were maintained on an AIN-76 diet (ICN Pharmaceuticals Inc, Cleveland) for 2 wk, after which they were given a daily dose of corn oil alone or 75 mg curcumin/kg in corn oil for 14 d. Their lenses were removed and cultured for 72 h in vitro in the presence or absence of 100 mumol 4-hydroxy-2-nonenal (4-HNE)/L, a highly electrophilic product of lipid peroxidation. The results of these studies showed that 4-HNE caused opacifications of cultured lenses as indicated by the measurements of transmitted light intensity using digital image analysis. However, the lenses from curcumin-treated rats were much more resistant to 4-HNE-induced opacification than were lenses from control animals. Curcumin treatment caused a significant induction of the glutathione S-transferase (GST) isozyme rGST8-8 in rat lens epithelium. Because rGST8-8 utilizes 4-HNE as a preferred substrate, we suggest that the protective effect of curcumin may be mediated through the induction of this GST isozyme. These studies suggest that curcumin may be an effective protective agent against cataractogenesis induced by lipid peroxidation.

Aldehydes↗
PubMed1996

Blood lead in pregnant women in the urban slums of Lucknow, India.

OBJECTIVES: To determine the concentrations of blood lead (PbB) in pregnant women in the slums of Lucknow, north India. METHODS: Of the 203 designated municipal slums in Lucknow, 70 were randomly selected for study and a cohort of 500 pregnant women was enrolled. Each participant was interviewed with questions on possible sources of exposure to lead, surrogates of nutritional status were measured, and PbB was measured. RESULTS: The mean PbB was 14.3 micrograms/dl and 19.2% of women had PbB > or = 20 micrograms/dl. PbB was not associated with age, height, weight, gestation, or history of abortions, although higher PbB was associated with higher parity. Women living inner city neighbourhoods near heavy vehicular traffic had PbB 2.2 micrograms/dl higher (95% confidence interval (95% CI) 0.8 to 3.6) than those living in other neighbourhoods. The PbB was not associated with reported use of piped water or the presence of paint in homes, and increasing PbB was unexpectedly associated with decreasing use of eye cosmetic "surma" and the duration of gestation. CONCLUSIONS: The high PbB found in this population raises concern about fetal development and points to the urgent need to reduce exposure to lead.

Adult↗
PubMed1996

Attenuation of 4-hydroxynonenal-induced cataractogenesis in rat lens by butylated hydroxytoluene.

PURPOSE: We have previously shown that 4-hydroxynonenal (4-HNE) causes opacification of cultured rat lenses and that a novel group of glutathione S-transferases (GSTs) exhibit high specific activity towards 4-HNE. Previous studies have shown that t-butylated hydroxy toluene (BHT) induced GSTs in cultured rat lens. Therefore, the purpose of the present studies was to investigate if the opacification of rat lenses exposed to 4-HNE is ameliorated by pre-culturing the lenses in media containing BHT. METHODS: Rat lenses were divided into four groups. Group I and II were controls and groups III and IV were cultured in the presence of 100 microM 4-HNE. Groups II and IV were pre-cultured in the media containing 10 microM BHT for 24 hrs which was designated as 0 time point. Lenses were withdrawn at 24 and 72 h and evaluated for opacification by digital image analysis. Induction of the specific GST isozyme (gammaGST8-8) was studied in the lens epithelium by immunohistochemical studies. Results. Digital image analysis revealed amelioration in opacification induced by 4-HNE, when the lenses were precultured with BHT. Immunohistochemical studies show that BHT induced GST8-8 several folds in the epithelium. CONCLUSIONS: These studies indicate that pretreatment with BHT would increase the lens capacity to detoxify 4-HNE by conjugating it with GSH, thus assigning an important detoxication role to this specific GST isozyme in oxidative cataract.

Aldehydes↗
PubMed1996

Effect of cooking fuels on respiratory diseases in preschool children in Lucknow, India.

The association between cooking fuels and the risk of respiratory disease in preschool children in Lucknow, India was studied. We interviewed mothers of 650 study children, randomly selected from among 28 urban poor neighborhoods. Children were eligible if they were less than five years of age, free of congenital heart disease, malignancy, and compromised immune status. Respiratory disease (defined as one or more of the following: runny nose, cough, sore throat, breathlessness, and noisy respiration) was assessed by observation. Exposures included the types of cooking fuels and duration of their use in the last week and other potential predictors of respiratory disease. Odds ratios (ORs) for disease were adjusted for covariables using multiple logistic regression. The point prevalence of respiratory disease was 14.5%. Cooking fuels used were wood (56.0%), kerosene (24.2%), coal (19.2%), gas (15.4%), and dung cakes (8.6%). Use of dung cakes, a sun-dried mixture of cow or buffalo dung and straw, as cooking fuel was associated with respiratory disease (adjusted OR = 2.69, 95% confidence interval [CI] = 1.37-5.31, P = 0.004), as was overcrowding in the bedroom (adjusted OR = 1.25 for each additional person, 95% CI = 1.11-1.41, P = 0.001). Age, weight, gender, family income, and household structure were not associated with disease. Use of dung cakes as cooking fuel and overcrowding in the bedroom increased the risk of respiratory disease. Interventions to modify oven design or install chimneys and, where feasible, to reduce the number of people sleeping together should be considered.

Child, Preschool↗