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Biomedical subjects

R C Sharma

Publications and source records attributed to R C Sharma.

At least 91 records · Page 5Linked to original sources
PubMed1993

Observations on mosquito breeding in wells and its control.

Studies on mosquito breeding in wells revealed the dominance of An. stephensi among the malaria vectors, whereas Cx. quinquefasciatus was most abundant in disused wells and was present in wells of all depths. None of the anopheline species was encountered when well depth up to water level exceeded 12 m. Larval breeding was effectively controlled through the introduction of larvivorous fish Poecilia reticulata and expanded polystyrene (EPS) beads in comparison to untreated control wells.

Animals↗
PubMed1993

Structure-activity relationship studies of 4-substituted-2-guanidinothiazoles: reversible inhibitors of gastric (H+/K+)-ATPase.

The role of physicochemical factors, electronic and hydrophobic, and a hydrogen donor index in the inhibition of gastric (H+/K+)-ATPase by 4-phenyl-2-guanidinothiazoles and the 4-indolyl-2-guanidinothiazoles has been quantitatively analysed. For the first congeneric series, the resonance effect of the ortho- and para-substituents and hydrogen donor property of the meta-substituent in the phenyl ring play crucial role, whereas for 4-indolyl analogues, the hydrophobicity and electron withdrawing effect of X-substituents in the indolyl ring are shown to be important decisive factors. Also the substitution of the guanidine moiety, e.g. by benzyl, raises the activity of proton pump inhibitors. The substitution at 5-position of thiazole ring does not enhance the potency.

Animals↗
PubMed1993

Interspecific associations among anophelines in different breeding habitats of Kheda district Gujarat: Part II--Non-canal area.

A total of 25,858 anophelines comprising 15 species emerged from 1104 samples of immatures from 9 breeding habitats surveyed for one year in six villages representing the non-canal area of Kheda district. Species diversity and homogeneity were maximum in seepage drains. An. annularis, An. barbirostris, An. culicifacies, An. stephensi and An. subpictus were ubiquitous. Interspecific associations occurred more commonly in habitats representing the stable ecosystem. Community groups of anophelines in different habitats were identified.

Animals↗
PubMed1992

Peptide transport by the multidrug resistance pump.

The membrane P-glycoprotein (P170) is an ATP-hydrolyzing transmembrane pump, and elevated levels of P170, due to higher expression with or without amplification of the multidrug resistance gene (mdr1), result in resistance to a variety of chemotherapeutic agents in mammalian cells. The function of the P170 pump has been proposed as a protection against toxic substances present in animal diets. Here we describe a Chinese hamster ovary cell line that was selected for resistance to a synthetic tripeptide, N-acetyl-leucyl-leucyl-norleucinal (ALLN). This ALLN-resistant variant shows the classical multidrug resistance (MDR) phenotype, including overexpression and amplification of the mdr1 gene. Additionally, a mouse embryo cell line overexpressing the transfected mdr1 gene is likewise resistant to ALLN. Our results demonstrate that P170 is capable of transporting peptides and raise the possibility that the mdr1 gene product or other MDR-like genes, present in the genome of mammalian cells, may be involved in secretion of peptides or cellular proteins as is the case with the structurally similar hylB and ste6 gene products of Escherichia coli and yeast, respectively.

3T3 Cells↗
PubMed1992

Characterization of the coexisting multiple mechanisms of methotrexate resistance in mouse 3T6 R50 fibroblasts.

We have studied the discrepancy in the degree of methotrexate (MTX) resistance that exists between two clonal cell lines, mouse 3T6 R50 cells and Chinese hamster ovary B11 0.5 cells that overexpress comparable levels of dihydrofolate reductase, yet exhibit a 100-fold difference in MTX resistance while maintaining similar sensitivity to the lipophilic antifolates trimetrexate and piritrexim. These data suggested that R50 cells may possess additional mechanism(s) of antifolate resistance, such as MTX transport alteration. Flow cytometric analysis using fluorescein methotrexate revealed comparable levels of fluorescein MTX displacement with lipophilic antifolates in viable R50 and B11 0.5 cells, but marked insensitivity of R50 cells to MTX competition, thus suggesting a poor uptake of MTX into R50 cells. Analysis of the kinetic parameters of dihydrofolate reductase from R50 cells neither showed alterations in enzyme affinities for various antifolates nor in the Michaelis constant for folic acid and NADPH nor a change in the pH activity optimum. R50 cell-free extracts contained wild-type levels of folylpoly-gamma-glutamyl synthetase activity. However, following metabolic labeling with [3H]MTX, no MTX polyglutamates could be detected in R50 cells. We conclude that the high level of MTX resistance in R50 cells is multifactorial, including overexpression of dihydrofolate reductase, reduced MTX transport, and possibly altered formation of MTX polyglutamates. The potential interactions between the different modalities of MTX resistance in R50 cells are being discussed.

Animals↗
PubMed1992

Immunolocalization of native antioxidant scavenger enzymes in early hypertensive and atherosclerotic arteries. Role of oxygen free radicals.

To elucidate the role of oxygen free radicals and lipid peroxidation in the pathogenesis of early hypertension and atherosclerosis, we studied the native distribution of three primary arterial antioxidant enzymes (AEs). Specific immunohistochemical localization of superoxide dismutase (Cu-Zn SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) was examined in the arterial wall of New Zealand White rabbits: six sham-operated normotensive/normolipidemics (NT/NL), seven coarctation-induced hypertensive/normolipidemics (HT/NL), eight normotensive diet-induced hyperlipidemics (NT/HL), and six hypertensive/hyperlipidemics (HT/HL). All three AEs were confined primarily to the endothelium in NT/NL rabbit aortas. However, in HT and HL rabbits a greater proportion of the arterial wall, including the endothelium, inner media, and middle media, displayed immunolocalization of three AEs. Multiple linear-regression analysis revealed that more than 70% of the total variability in the depth of immunolocalization of arterial AEs could be explained by changes in blood pressure and/or total cholesterol. Also, levels of plasma and arterial cholesterol oxides were significantly different (p less than 0.05) in HT and HL rabbits compared with controls, with twofold increases in NT/HLs, threefold increases in HT/NLs, and fourfold increases in HT/HLs. We conclude that intense free-radical activity in the arterial wall of HT and HL animals is one possibility and that this occurs despite the presence of abundant AEs.

Animals↗
PubMed1992

Frequency of ABO blood groups, sickle-cell haemoglobin, G-6-PD deficiency and their relation with malaria in scheduled castes and scheduled tribes of Kheda District, Gujarat.

Frequency of sickle cell in Scheduled Caste and Scheduled Tribe populations was found to be 1.5 and 14.9% respectively, whereas G-6-PD deficiency was 5.9 and 4.2% respectively. Blood group B was dominant in both the communities. A significantly lower frequency of P. falciparum malaria was observed among sicklers.

ABO Blood-Group System↗
PubMed1992

Quantitative structure-activity relationship study of some benzodiazepine-receptor ligands having inverse agonist/antagonist and agonist actions.

Quantitative structure-activity relationship (QSAR) analyses of three different series of benzodiazepine ligands, pyridodiindoles, and beta-carbolines, having inverse agonist/antagonist and agonist actions have been performed with a view to understanding their likely mode of action at the benzodiazepine-receptor (BzR). From this study, the in vitro radioligand displacement activities of substituted 7,12-dihydropyrido[3,2-b: 5,4-b']diindoles (Figure 1) were found to be significantly correlated with resonance effect of R-substituents, van der Waals volumes at positions-1 and -3, hydrophobic constant at position-2 and field effect at position-4 of X-substituents. For 3-substituted beta-carbolines, a similar analysis has established that R-substituents at position-3 of beta-carbolines (Figure 2) are involved in strong hydrophobic interaction with some hydrophobic pocket on the receptor. For the analogues of 6-(benzyloxy)-4-(methoxymethyl)-beta-carbolines-3-carboxylic acid ethyl ester (Figure 3), however, the combined hydrophobicities of 6- and 4-substituents were shown to be important in determining ligand binding behaviour. The significant correlations so obtained are in agreement with the proposed models (Figures 4 and 5) of pharmacophores of inverse agonist/antagonist and of agonist sites at the BzR.

Carbolines↗
PubMed1992

Epidemiological profile of Japanese encephalitis in Gorakhpur district, Uttar Pradesh, 1982-1988.

An in-depth study of Japanese Encephalitis (JE) situation in Gorakhpur district of Uttar Pradesh from 1982-1988 showed increasing trend in the incidence of JE. Total number of annual cases and case fatality rate (CFR) rose from 118 and 23.7 per cent in 1982 to 772 and 32.2 per cent in 1988 respectively. A definite increase was noticed in the number of cases per block following lull years in 1984 and 1987. Among the total affected 1201 villages, 1083 were affected only once. All age groups were affected and the disease showed marked seasonality during August to November. JE, which came in epidemic form in earlier years has established in the area in endemic form.

Adolescent↗
PubMed1992

Diarrhoeal diseases amongst children under five. A study in rural Alwar.

A house to house survey was done in three villages of district Alwar covering 875 children under five years age. Two week incidence of diarrhoea morbidity was 2.27 episodes/child/year taking into consideration the seasonal correction factor. The incidence decreased with increase of age. Incidence was found significantly more in children of illiterate mother (p < 0.05). Children of poor socio-economic conditions as determined by occupational status (labourers) suffered significantly more often from diarrhoea as compared to children of higher socio-economic status (agriculturist and others). Fifty per cent episodes of diarrhoea were treated with antibiotics, and only one child was given ORS. It is a matter of concern. About 3.7 per cent mothers washed their hands before preparing meals while, 1.6 per cent washed their hands after toilet. Only 2 per cent mothers had the knowledge of preparing the home made salt sugar solution. An intensive health education campaign is therefore, necessary for health professionals as well as mothers.

Child, Preschool↗
PubMed1992

Seasonal prevalence and succession of rice field breeding mosquitoes of central Gujarat.

Studies on seasonal prevalence and succession of mosquitoes in rice fields, revealed the dominance of Anopheles culicifacies and An. subpictus in newly transplanted fields during early months of rice cultivation, which was later replaced by the species like An. annularis, An. barbirostris, An. nigerrimus and An. tessellatus with the growth in plant height. Among culicines, except Cx. quinquefasciatus other species were prevalent during growing and later stages of the rice crop. Larval density was found inversely proportional to the height of plants, whereas species diversity maximized during growing phase due to equitable number of specimen among species.

Agriculture↗
PubMed1992

An epidemiological study of G-6-PD deficiency, sickle cell haemoglobin, and ABO blood groups in relation to malaria incidence in Muslim and Christian communities of Kheda, Gujarat, (India).

783 blood samples for the study of distribution of ABO blood groups and sickle cell haemoglobin in relation to malaria, from both the sexes of Muslim and Christian populations of Kheda district were screened. 414 blood samples from male individuals were screened for G-6-PD deficiency. High frequency of G-6-PD deficiency was observed in Christians (5.9%) and low in Muslim (1.8%) population, whereas sickle cell haemoglobin in Muslim population was 1.5% and absent in Christians. Blood group B was dominant in both the communities. Significant association of ABO polymorphs with P. falciparum and total malaria cases was observed.

ABO Blood-Group System↗
PubMed1992

Intradomestic mosquito breeding sources and their management.

Seven mosquito species were found to breed in intradomestic breeding sources. An. stephensi and An. subpictus bred in almost all types of containers. Among the culicines, Cx. quinquefasciatus and Ae. aegypti were predominant. Larval breeding was controlled through source reduction or introduction of larvivorous fish Poecilia reticulata. Health education helped in acceptance of the programme by the community. Intradomestic breeding positivity was 2-6% and 16-31% in experimental and control areas respectively.

Aedes↗