Search PubMed⌕ Search

Biomedical subjects

S Sharma

Publications and source records attributed to S Sharma.

At least 775 records · Page 43Linked to original sources
PubMed1996

Partial purification and characterization of cyclic adenosine monophosphate dependent protein kinase from mycobacterium smegmatis.

Adenosine 3' 5'-monophosphate (cyclic AMP) - dependent protein kinase was purified about 42 fold from the M. smegmatis by ammonium sulphate fractionation followed by DEAE-cellulose and phosphocellulose column chromatography. SDS-PAGE revealed two prominent bands, with molecular masses of 55 KDa and 58 KDa. The enzyme preferentially utilized phosvitin and Histones as exogenous phosphate acceptor. Mg2+ ions were essential for enzyme activity, other metal ions like Ca2+, Zn2+, Co2+ and Mn2+, could not substitute for Mg2+. Inhibition of enzyme activity by thiol reagents, 5-5'-dithio bis (2-nitrobenzoic acid) and N-ethylmaleimide suggest that the cystein residues in the protein kinase might be located at or near the active site of the enzyme.

Amino Acid Sequence↗
PubMed1996

Changes in the cellular composition of Candida albicans resistant to miconazole.

Biochemical changes that accompany acquisition of miconazole resistance in a single step mutant of C. albicans 3153 were analyzed. Experiments show that resistance to this drug was associated with decrease in total lipids, phospholipids and sterol content. Fluorescence polarization studies with 1,6-diphenyl-1,3,5-hexatriene (DPH) showed decrease in polarization value (p) in resistant cells, thus indicating changes in membrane fluidity. Uptake of [3H] proline by intact cells revealed decrease in K(m) and Vmax of high affinity system (S1) of proline transport in cells resistant to miconazole. Results of this study suggest that membrane sensitivity of miconazole is determined by overall membrane organisation rather than by affinity of antifungal drug(s) for a single membrane component.

Antifungal Agents↗
PubMed1996

Biological behaviour of moderate dysplasia--a prospective study.

The present communication reports the biological behaviour of women with moderate dysplastic lesions of uterine cervix based on a long term prospective study. Two hundred and thirty nine women with moderate dysplasia by cervical cytology who satisfied the criteria for registration were longitudinally followed up at 3 +/- 1 monthly intervals along with age and parity matched controls for a period ranging from 4 to 132 months. The cumulative rate of progression from moderate dysplasia to malignancy (CIS) was observed to be 23.0% at the end of 72 months of follow up with mean transition interval of 24.2 months. Out of 239 cases, 142 women who had more than 24 months of follow up were considered for studying the biological behaviour of the lesion. It was observed that during a follow up of 132 months, 14(9.9%) and 15(10.6%) women progressed to carcinoma in-situ and severe dysplasia respectively. The persistence of lesion was observed in 21(14.8%) women while 11(7.3%) and 81(57.0%) regressed to mild dysplasia and normalcy respectively.

Carcinoma in Situ↗
PubMed1996

Prevalence of asymptomatic electrocardiographic abnormalities in a rural population.

To determine the prevalence of various electrocardiographic (ECG) abnormalities among asymptomatic individuals in a rural population of India we performed a 12-lead ECG during a comprehensive cardiovascular survey in three randomly selected villages in Rajasthan. Twenty four of 3148 individuals with a past diagnosis or symptoms suggestive of coronary heart disease (CHD) were excluded. ECG of 3124 persons (males 1965, females 1159) were analysed and classified according to the WHO-Minnesota Code. The prevalence rate/1000 of Q-waves was 8.6 (males 8.7, females 8.6) and ST-T wave changes was 17.0 (males 12.7, females 24.2). An age-related increase in prevalence of Q-waves was seen (X2 for trend p < 0.01). The Q wave prevalence was similar among males and females but ST-T changes were more frequent in females (p = 0.0016). Other prevalent findings were left ventricular hypertrophy in 8.3, right or left bundle branch block pattern in 18.6, left or right axis deviation in 10.6, atrioventricular conduction defects in 10.2 and ventricular arrhythmia in 1.3/1000 population.

Adult↗
PubMed1995

Immunosuppressive drugs prevent a rapid dephosphorylation of transcription factor NFAT1 in stimulated immune cells.

The immunosuppressive drugs cyclosporin A and FK506 interfere with the inducible transcription of cytokine genes in T cells and in other immune cells, in part by preventing the activation of NF-AT (nuclear factor of activated T cells). We show that transcription factor NFAT1 in T cells is rapidly dephosphorylated on stimulation, that dephosphorylation occurs before translocation of NFAT1 into the cell nucleus, and that dephosphorylation increases the affinity of NFAT1 for its specific sites in DNA. Cyclosporin A prevents the dephosphorylation and the nuclear translocation of NFAT1 in T cells, B cells, macrophages, and mast cells, delineating at least one mechanism that contributes to the profound immunosuppressive effects of this compound.

Animals↗
PubMed1995

Characterization of transforming growth factor-beta 1 induced apoptosis in normal human B cells and lymphoma B cell lines.

Transforming growth factor beta 1 (TGF beta 1) has been shown to inhibit growth stimulation in normal human B cells as well as in Epstein Barr virus (EBV)-negative Burkitt's lymphoma (BL) cell lines. The mechanisms for this potent growth inhibition are not completely defined. Here we show that a number of EBV-negative lymphoma B cell lines (BL-41, Ramos and CAPA-2), when exposed in vitro to TGF beta 1, undergo apoptosis. Maximum apoptosis was observed at 48 h following TGF beta 1 treatment, with no apparent effect on the expression of c-myc and bcl-2 proteins. Similar induction of apoptosis was observed when these lymphoma cell lines were treated with aphidicolin, a DNA synthesis inhibitor. In contrast, various preparations (14 out of 17) of normal human tonsilar B cells showed no significant apoptosis, although both TGF beta 1 and aphidicolin inhibited anti-mu/IL-4 induced DNA synthesis in all preparations. Furthermore, another TGF beta 1 sensitive EBV-negative BL cell line, CA46, exhibited no apoptosis in response to TGF beta 1 and aphidicolin, corroborating the findings in normal human B cells. Taken together, these data support the hypothesis that exposure to TGF beta 1, which results in cell cycle arrest and DNA synthesis inhibition, may not be obligatory or sufficient for the induction of apoptosis. Rather, induction of apoptosis or lack of it may be intrinsically determined by an interplay between extracellular and intracellular regulators of cellular growth.

Aphidicolin↗
PubMed1995

Phosphorylation of the transcription factor NFATp inhibits its DNA binding activity in cyclosporin A-treated human B and T cells.

Cyclosporin A (CsA) exerts its immunosuppressive effect by inhibiting the activity of nuclear factor of activated T cells (NFAT), thus preventing transcriptional induction of several cytokine genes. This effect is thought to be largely mediated through inactivation of the phosphatase calcineurin, which in turn inhibits translocation of an NFAT component to the nucleus. Here we report that CsA treatment of Raji B and Jurkat T cell lines yields a phosphorylated form of NFATp that is inhibited in DNA-binding and in its ability to form an NFAT complex with Fos and Jun. Immunoblot analyses and metabolic labeling with [32P]orthophosphate show that CsA alters NFATp migration on SDS-polyacrylamide gel electrophoresis by increasing its phosphorylation level without affecting subcellular distribution. Dephosphorylation by in vitro treatment with calcineurin or alkaline phosphatase restores NFATp DNA binding activity and its ability to reconstitute an NFAT complex with Fos and Jun proteins. These data point to a new mechanism for CsA-sensitive regulation of NFATp in which dephosphorylation is critical for DNA binding.

Alkaline Phosphatase↗
PubMed1995

Human non-small cell lung cancer cells express a type 2 cytokine pattern.

In addition to infiltrating inflammatory cells, tumors also produce cytokines and growth factors that may alter tumor growth, tumor immunogenicity, and the host immune response. To characterize the expression profile of human non-small cell lung cancer (NSCLC)-derived cytokines, the mRNA expression of type 1 and type 2 cytokines in five human NSCLC lines was analyzed by reverse transcriptase-PCR. Expression of interleukin 5 (IL-5) and IL-10 was demonstrated in all tumor lines evaluated, whereas IL-4 was present in three of five lines and IL-13 was present in two of five lines. In contrast, none of the tumor lines expressed IL-2 and IFN-gamma. Type 2 cytokine protein production by NSCLC lines was confirmed by immunoprecipitation and cytokine specific ELISA. Tumor-derived IL-10 secretion was significantly augmented by exogenous recombinant cytokines including IL-4 and tumor necrosis factor-alpha. To evaluate whether fresh NSCLC nodules also express a type 2 cytokine pattern, the content of type 1 and type 2 cytokines in tissue homogenates from 13 fresh NSCLC nodules and normal lung surgical specimens was assessed. Human NSCLC nodules contain significantly more type 2 cytokines than does normal lung tissue when corrected for total protein concentration. To identify the cellular source of type 2 cytokine production in tumor nodules, immunohistology was performed on sections from 5 lung squamous cell carcinomas and 5 adenocarcinomas. All of the specimens revealed positive staining for type 2 cytokines within tumor cells. In summary, we report that human NSCLC cells produce type 2 cytokines both in situ and in vitro, which may play an active immunoregulatory role in the lung cancer microenvironment.

Base Sequence↗
PubMed1995

Latent membrane protein-1 induces cyclin D2 expression, pRb hyperphosphorylation, and loss of TGF-beta 1-mediated growth inhibition in EBV-positive B cells.

The normal cell cycle is regulated by several molecules, such as the tumor-suppressor protein pRb, the G1 cyclins, the cyclin-dependent kinases, and their inhibitors. These regulators are targeted by negative growth regulatory signals, such as that provided by TGF-beta. Here, we show that the presence of either wild-type EBV or its transforming latent membrane protein-1 (LMP-1) results in the loss of TGF-beta 1-mediated growth inhibition in human B cells. Chemical cross-linking with 125I-labeled TGF-beta 1 showed an essentially normal TGF-beta receptor profile in EBV-positive and EBV-negative Burkitt's lymphoma cell lines, and these receptors were shown to be functional in transducing signals, as evidenced by the TGF-beta 1-mediated modulation of junB gene expression. However, TGF-beta 1 did not induce dephosphorylation of pRb in EBV (or LMP-1)-positive cells as opposed to EBV-negative cells, suggesting a dichotomy in the TGF-beta 1 signaling pathway leading to separable gene regulatory and growth inhibitory responses. Furthermore, LMP-1 was found to induce the expression of cyclin D2; normal B cells or EBV-negative Burkitt's lymphoma cells do not express D-type cyclins. Taken together, these data point to a potential mechanism underlying EBV-mediated B cell transformation whereby constitutive induction of key cell cycle regulators by LMP-1 can lead to pRb hyperphosphorylation and uncontrolled cell proliferation.

B-Lymphocytes↗
PubMed1995

Decreased plasma glutathione in cancer of the uterine cervix.

Plasma total glutathione (GSH) content (reduced plus oxidized) was estimated in varying grades of cervical intraepithelial neoplasia (CIN) and in invasive cervical cancer. The values were compared with age-matched control women. The results show significantly lower level of plasma GSH in CIN III and invasive cancer compared to controls (0.724 versus 1.082 and 0.622 versus 1.082 mumol/ml of plasma, P < 0.05). Further, the odds ratio analysis showed high plasma GSH content was found to be protective against the development of cervical cancer. The results suggest a plausible association of plasma GSH with cervical carcinogenesis. The quantitative changes occurring in plasma total glutathione during cervical carcinogenesis is a useful finding and might represent a systemic biochemical marker for precancerous and cancerous lesions of the uterine cervix.

Adult↗