Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 937 records · Page 52Linked to original sources

PubMed1995

Identification of alpha 1-adrenergic receptor subtypes in human corpus cavernosum tissue and in cultured trabecular smooth muscle cells.

Recent pharmacological and functional studies have suggested the presence of more than one alpha-1 adrenergic receptor subtype in human corpus cavernosum (HCC). In this study, we sought to identify the alpha-1 adrenergic receptor (alpha 1-AR) subtypes expressed in HCC whole tissue and in trabecular smooth muscle subcultured from this tissue. We have utilized RNase protection assays and in situ hybridization (ISH) techniques to identify and localize these receptor subtypes. RNase protection assays of mRNA isolated from whole tissue demonstrated the presence of mRNA transcripts for three alpha 1-AR receptor subtypes (alpha 1d, alpha 1b, and alpha 1a). alpha 1d-AR and alpha 1a-AR appear to be more abundant than alpha 1b-AR. The identification and localization of mRNA for alpha 1-AR subtypes in whole tissue was demonstrated by RNA protection assays and ISH analysis. Immunocytochemical analysis of alpha 1-AR by an antipeptide antibody developed against a specific amino acid sequence derived from alpha 1d-AR subtype demonstrated specific staining of the smooth muscle cells, suggesting the expression of alpha 1d-AR subtype. In cultured HCC smooth muscle cells (HCC SMC), phenylephrine,alpha 1-AR agonist stimulated Na+/K+ ATPase activity, suggesting the presence of functional alpha 1-AR. RNase protection assay of mRNA isolated from HCC SMC grown in culture further demonstrated the presence of mRNA transcripts for alpha 1d-AR and alpha 1a-AR subtypes. ISH analysis and confocal microscopy also indicate that the SMC express the alpha 1d-AR and alpha 1a-AR subtypes. The data presented suggests that HCC and SMC derived from this tissue express at least three alpha 1-AR subtypes. Identification of these receptor subtypes should allow characterization of the functional role of these receptor subtypes in regulation of trabecular smooth muscle tone and penile detumescence.

Cells, Cultured↗

PubMed1995

Lipid profile norms in Indian children.

OBJECTIVES: To evaluate the lipid parameters in normal Indian children. DESIGN: Cross-sectional. SETTING: Hospital based. METHODS: 410 children (siblings of hospitalized pediatric cases) between 3-12 years were evaluated for total plasma cholesterol (TC), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C). The low density lipoprotein cholesterol (LDL-C) levels were derived from the above parameters using Fredrickson-Friedwald formula. RESULTS: No significant difference was found between the sexes in any of the lipid parameters studied. The mean values were: TC-134.5 mg/ dl, TG-91.1 mg/dl, HDL-C-34.15 mg/dl and LDL-C-80.1 mg/dl. The suggested cut off limits for these parameters were 190 mg/dl, 150 mg/dl, 20 mg/dl and 130 mg/d respectively. CONCLUSIONS: Lipid profile norms and cut off levels to define abnormalities for Indian children were recommended. The HDL-C levels were lower than western data.

Child↗

PubMed1995

Regulation of an eukaryotic initiation factor-2 (eIF-2) associated 67 kDa glycoprotein (p67) and its requirement in protein synthesis.

The p67 mRNA level and p67 requirement in protein synthesis were studied using an animal cell (KRC-7, rat tumor hepatoma cell) in culture. p67 mRNA was present in confluent cells but disappeared almost completely from serum-starved cells. However, when PMA was added to the serum-starved cells, p67 mRNA appeared in increasing quantities. Several-fold molar excess of p67 mRNA over that present in confluent cells was detected within 2 h of PMA addition and this level remained the same during the 4 h of the experiment. p67 requirement in protein synthesis was studied using a p67 antisense DNA construct under a metallothionein gene promoter. Expression of this antisense DNA in the presence of zinc in PMA-induced serum-starved cells completely inhibited induced appearance of p67 mRNA and subsequent protein synthesis. These results suggest that p67 is regulated at the mRNA level and also that this protein factor is essential for protein synthesis.

Aminopeptidases↗

PubMed1995

Serodiagnosis of tuberculosis.

To overcome limitations of the conventional laboratory tests for the diagnosis of tuberculosis, attempts have been made in the past to develop a good serodiagnostic test. Until the availability of ELISA results obtained with various immunological techniques were of limited use. Even with ELISA, early attempts to estimate specific antimycobacterial antibodies in the serum were based on the use of crude mycobacterial antigens resulting in a very high false positivity. Better results were obtained with purified antigens. Various purified and semipurified antigens which when used in the ELISA test for estimating antibodies in the serum and other body fluids in cases of tuberculosis have given encouraging results. These include a glycolipid antigen from Myc. bovis BCG (ST = 88%, SP = 96%), antigen '5' (ST = 72%, SP = 91%) and a 38 Kd protein antigen (ST = 83%). Estimation of various mycobacterial antigens in different clinical specimens has also been studied using ELISA technique. Encouraging results have been obtained with the detection of a 43 Kd antigen, Lipoarabinomannan antigen and antigen '5' in the serum, CSF and other body fluids of cases of tuberculosis (ST = 80-100%, SP = 93-100%). The serological tests by detecting specific mycobacterial antigens and antibodies can be of great help in diagnosing the smear negative tuberculosis as these are rapid, inexpensive and simple to perform.

Enzyme-Linked Immunosorbent Assay↗

PubMed1995

Seroprevalence of rubella in women of reproductive age.

This study was conducted on 160 females of childbearing age and 40 girls of prefertility age group. The rubella immunity status was analysed according to their age, social class, geographical distribution and previous obstetric history. History of previous rubella infection was obtained in 12% cases only. The over all incidence of rubella immunity was found to be 55%. There was a gradual increase in the immunity status, with peak incidence of 66% between 30 to 34 years of age. Females of low socioeconomic status showed higher incidence of immunity (63%) compared to social class I (40%). Rubella immunity was higher in urban female population (57%), where-as only 49% of rural females were immune to rubella virus infection. The immunity status of women with previous BOH was higher (61%) as compared to those with normal obstetric performance (54.6%). From the above observations, it was concluded that a substantial number of women enter child bearing without immunity to rubella. A simple HAI test for rubella antibody (IgG) can be a good pointer to pick up susceptible female population and the seronegative females should be immunised against rubella before they contemplate pregnancy.

Adolescent↗

PubMed1995

Neuroticism and stressful life events in patients with non-ulcer dyspepsia.

Hindi adaptation of the Middlesex Hospital Questionnaire (MHQ), Brief Psychiatric Rating Scale and Presumptive Stressful Life Events Scale were used to measure neuroticism, psychiatric morbidity and stressful life events in 35 patients with non-ulcer dyspepsia (NUD), 22 cass of peptic ulcer disease (PUD), 65 irritable bowel syndrome (IBS) and 45 age and sex matched healthy controls. NUD subjects had significantly higher total MHQ scores (28.8 +/- 11.3; p < 0.001) and scores in subscales of somatization (7.8 +/- 3.4; p < 0.001) and hysterical personality traits (5.5 +/- 2.8; p < 0.01) compared to healthy controls. MHQ scores in IBS subjects was significantly higher than in NUD, but in PUD subjects it was in-between NUD and healthy controls. Psychiatric morbidity, as assessed by Brief Psychiatric Rating Scale, was significantly higher in patients with NUD and IBS than in normal controls. Stressful Life event score was statistically similar in all the groups.

Adult↗

PubMed1995

Assessment of puberty growth spurt in boys and girls--a dental radiographic method.

The first radiographic appearance of adductor sesamoid bone of thumb is considered reliable and is the most commonly used indicator of puberty growth spurt. The purpose of this study was to find out whether the tooth mineralization stage/stages were as reliable an indicator of puberty growth spurt as the adductor sesamoid bone. Puberty assessment has its necessary application in diagnosis, treatment planning of various malocclusions and in medico legal cases. The results indicated that a close relationship existed between tooth mineralization Stage G and appearance of the sesamoid bone. Hence it can be used in dentistry as an indicator for onset of puberty growth spurt via periapical or panoramic radiographs. The result of this study were not applicable to boys as the apical closure of these teeth had already occurred at the time of early radiographic appearance of the adductor sesamoid bone.

Adolescent↗

PubMed1994

Human leukocyte antigens and natural selection by malaria.

The extraordinary polymorphism of human leukocyte antigens (HLA) poses a question as to how this remarkable diversity arose and is maintained. The explanation that infectious pathogens are largely responsible is theoretically attractive but clear and consistent associations between HLA alleles and major infectious diseases have rarely been identified. Large case-control studies of HLA types in African children with severe malaria indicate that HLA associations with this parasitic infection do exist and it is becoming possible to investigate the underlying mechanisms by identification of peptide epitopes in parasite antigens. Such analysis reveals how the magnitude and detectability of HLA associations may be influenced by numerous genetic and environmental factors. These complex interactions will give rise to variation over time and space in the selective pressures exerted by infectious diseases and this fluctuation may, in itself, contribute to the maintenance of HLA polymorphism.

Biological Evolution↗

PubMed1994

Involvement of Janus kinases, p52shc, Raf-1, and MEK-1 in the IL-6-induced mitogen-activated protein kinase cascade of a growth-responsive B cell line.

We have previously shown that the IL-6R in a growth-responsive B cell line, AF10, induces activation of mitogen-activated protein (MAP) kinase. Here we demonstrate the activation of Raf-1 and MEK-1, which act as a MAP kinase kinase kinase and a MAP kinase kinase, respectively, in the MAP kinase cascade induced by IL-6 in AF10 cells. IL-6 also induced tyrosine phosphorylation of the signaling transducing subunit of the IL-6R in AF10 cells, along with tyrosine phosphorylation of the gp130-associated tyrosine protein kinase JAK1 and the adaptor molecule p52shc. Although induction of tyrosine phosphorylation and activation of MAP kinase by IL-6 in a differentiation-responsive B cell line, SKW 6.4, were below the limits of detection, the phorbol ester PMA did activate Raf-1, MEK-1, and MAP kinase without inducing the phosphorylation of gp130, JAKs, or p52shc. These results suggest that JAK kinase family members associated with the IL-6R may participate in the activation of MAP kinase in AF10 cells by way of an adaptor protein and Ras-dependent kinase cascade.

Adaptor Proteins, Signal Transducing↗

PubMed1994

MAP kinase binds to the NH2-terminal activation domain of c-Myc.

The transcription factor c-Myc is a substrate for phosphorylation by MAP kinases. Here we demonstrate that MAP kinase binds to c-Myc. The NH2-terminal region (residues 1-100) is necessary and sufficient for this interaction. Binding to c-Myc is not dependent on the state of MAP kinase activation. However, the c-Myc/MAP kinase complex is disrupted by ATP. Together, these observations indicate that substrate binding interactions contribute to the specificity of phosphorylation by MAP kinases.

Adenosine Triphosphate↗

PubMed1994

Volume-activated chloride current is not related to P-glycoprotein overexpression.

It has been suggested that P-glycoprotein (P-gp), an ATP-dependent transporter responsible for classical multidrug resistance, is also a volume-regulated chloride channel. We reexamined this hypothesis by use of whole-cell patch clamp recordings of three matched pairs of cell lines, which were either drug-sensitive or drug-resistant due to P-gp overexpression. We demonstrate here that volume-regulated chloride-selective currents can be induced in cells with or without P-gp expression. Overexpression of either P-gp or cystic fibrosis transmembrane conductance regulator, the protein product of the CF gene and another member of the ATP-dependent transporters, is associated with a hypotonicity-induced, rapid onset, transient current prior to onset of the volume-sensitive chloride-selective current, an apparent nonspecific effect related to the overexpression of an integral membrane protein. These results suggest that there is no relationship between P-gp and the chloride channel activated by cell swelling.

3T3 Cells↗

PubMed1994

The T-cell antigen receptor utilizes Lck, Raf-1, and MEK-1 for activating mitogen-activated protein kinase. Evidence for the existence of a second protein kinase C-dependent pathway in an Lck-negative Jurkat cell mutant.

T-cell antigen receptor (TCR) ligation of an Lck-deficient Jurkat mutant, J.CaM1, with anti-CD3 or anti-TCR beta monoclonal antibodies failed to induce tyrosine phosphorylation and activation of p42MAPK. The same stimuli activated mitogen-activated protein (MAP) kinase in J.CaM1 cells transfected with Lck, demonstrating that Lck plays a critical role in MAP kinase activation. Utilizing immunocomplex kinase assays, we demonstrated that TCR/CD3 ligation activated a MAP kinase kinase kinase (Raf-1) as well as a MAP kinase kinase (MEK-1) in Jurkat but not in J.CaM1 cells. It was possible, however, to activate Raf-1, MEK-1, and p42MAPK in J.CaM1 cells during treatment with the phorbol ester phorbol 12-myristate 13-acetate, which activates protein kinase C (PKC). This demonstrates the presence of a PKC-dependent pathway which functions independently from Lck in MAP kinase activation. Stimulation of Jurkat cells with either anti-TCR beta or anti-CD3 monoclonal antibody failed to induce substantial tyrosine phosphorylation of Shc proteins or their association with Grb2 which forms a complex with the guanine nucleotide exchange factor hSOS. However, the same stimuli induced tyrosine phosphorylation of another putative guanine nucleotide exchange factor, p95Vav, in Jurkat but not J.CaM1 cells. Moreover, Lck was reversibly co-immunoprecipitated with p95Vav, and the stoichiometry of binding increased in anti-CD3-treated Jurkat cells. Phorbol 12-myristate 13-acetate did not induce tyrosine phosphorylation of p95Vav. These data show that the TCR activates MAP kinase by way of a signaling cascade, which depends upon Lck, and may be mediated by downstream events involving PKC or p95Vav which act on Raf-1 and MEK-1.

Cell Line↗

PubMed1994

Theoretical studies of the effects of heterogeneity in the parasite population on the transmission dynamics of malaria.

Periodicity in malaria transmission has generally been ascribed to seasonal fluctuations in mosquito population density or spatial heterogeneity with periodic migration. In this paper we demonstrate that simple models of strain heterogeneity can generate periodic behaviour as a consequence of the interaction between parasite strains and host immunological defences. As the degree of cross-immunity between strains increases, the system moves from a régime of independent strain transmission and coexistence, through increasingly coupled behaviour, to the displacement of the strain of lower transmissibility by the strain with a higher basic reproductive rate (R0). Cross-immunity thus serves both to bring the strains into competition, and also to couple the dynamics. We find analytical and numerical results on strain coexistence to show how the range of possible outcomes may be read as an effect of the tension between these two effects of cross-protection.

Animals↗

PubMed1994

Diquat- and acetaminophen-induced alterations of biliary efflux of iron in rats.

The effects of diquat on the biliary efflux of nonheme iron in rats were studied as a means of examining the possible effects of diquat metabolism on hepatocellular iron metabolism and the association of altered iron metabolism with the initiation of acute hepatic necrosis. Administration of hepatotoxic doses (0.1 mmol/kg) of diquat to male Fischer-344 rats increased biliary iron concentrations from 6 microM to more than 15 microM. However, increases in biliary efflux of iron were not observed during the first 60 min following exposure to diquat, despite the rapid increases in biliary glutathione disulfide concentrations, which increased maximally within 40 min. Biliary efflux of iron was not altered by diquat in Sprague-Dawley rats, which are resistant to hepatic necrosis in response to diquat, despite the marked oxidant stress responses observed in these animals. Conversely, hepatotoxic doses of acetaminophen (1500 mg/kg) caused significant decreases in biliary iron efflux. The rapid decreases in biliary iron caused by acetaminophen and the delay in diquat-induced iron efflux suggested the possibility that some fraction of the biliary iron was being excreted as reversibly formed GS-Fe2+ chelates, with inhibition of export by glutathione disulfide (GSSG) in the case of diquat, or by 3-(glutathion-S-yl)-acetaminophen (GS-AAP) in the case of the acetaminophen-treated animals. However, 50-200 mg/kg doses of acetaminophen showed little effect on biliary iron excretion despite producing biliary GS-AAP conjugate concentrations almost 1000 times the 6 microM concentrations of iron, which would not appear to support the hypothesis of excretion of GS-Fe2+ chelates. The data demonstrate a significant effect of diquat on hepatic iron metabolism in Fischer-344 rats, and the possible importance of this iron redistribution to reactive oxygen-mediated cell damage in vivo is indicated by the absence of similar responses in diquat-treated Sprague-Dawley rats.

Acetaminophen↗

PubMed1994

Salmonella typhimurium activates human immunodeficiency virus type 1 in chronically infected promonocytic cells by inducing tumor necrosis factor-alpha production.

The effect of phagocytosis of Salmonella typhimurium on human immunodeficiency virus type 1 (HIV-1) production was investigated using a chronically infected promonocytic cell line (U1) that contains HIV-1 provirus but produces little or no HIV-1. The phagocytosis of virulent S. typhimurium by U1 cells resulted in an increased HIV-1 expression as evidenced by significant increase in HIV-1 p24 antigen in culture supernatants. In contrast, heat-killed S. typhimurium failed to induce HIV-1 expression. In addition, phagocytosis of virulent S. typhimurium and not of heat-killed S. typhimurium resulted in a significant induction of tumor necrosis factor-alpha (TNF-alpha) mRNA expression and secretion of TNF-alpha by U1 cells. Furthermore, anti-TNF-alpha monoclonal antibody inhibited S. typhimurium-induced HIV-1 p24 antigen production. These data suggest that S. typhimurium induces HIV-1 expression in U1 cells via production of TNF-alpha.

Cell Line↗

PubMed1994

Activation of a novel serine/threonine kinase that phosphorylates c-Fos upon stimulation of T and B lymphocytes via antigen and cytokine receptors.

Ligation of Ag receptors in T and B lymphocytes initiates signal transduction cascades which alter the expression of genes that regulate cellular proliferation and differentiation. The transmission of signals from the membrane to the nucleus is mediated principally through the action of protein tyrosine and serine/threonine kinases. We have identified and characterized a novel serine/threonine kinase that phosphorylated the proto-oncogene product, c-Fos, and is termed Fos kinase. Fos kinase was rapidly activated after ligation of the CD3 and CD2 receptors in Jurkat and normal human T lymphocytes and in response to IL-6 and anti-IgM in the human B cell lines AF10 and Ramos, respectively. The phorbol ester, PMA, was also a potent inducer of Fos kinase activity in all of the above populations, suggesting that PKC plays a role in the regulation of this enzyme. Fos kinase phosphorylates c-Fos at a site near the C-terminus, as well as a peptide derived from this region (residues 359-370, RKGSSSNEPSSD), and Fos peptide competitively inhibited c-Fos phosphorylation. Fos kinase was shown to be distinct from other identified serine/threonine kinases, including protein kinase A, protein kinase C, casein kinase II, MAP kinases, p70S6K and p90RSK. Fos kinase was purified by anion exchange chromatography and exhibited an apparent M(r) = 65,000 and isoelectric point = 6.1. Fos kinase may play a role in transcriptional regulation through its capacity to phosphorylate c-Fos at a site required for expression of the transcriptional transrepressive activity of this molecule. Moreover, its rapid activation suggests it may have a wider role within signal transduction cascades in lymphocytes.

Amino Acid Sequence↗

PubMed1994

Parasite virulence and disease patterns in Plasmodium falciparum malaria.

Heterogeneity in parasite virulence is one of several factors that have been proposed to contribute to the wide spectrum of disease severity in Plasmodium falciparum malaria. We used observed age-structured patterns of disease to define a population structure of P. falciparum, where the latter contains several independently transmitted antigenic types or "strains" that each induce some degree of strain-specific antidisease immunity upon infection. Patterns of incidence of severe and mild disease may be explained by assuming that a majority of these strains are associated with mild disease and that although severe malarial anemia is a complication occurring in a certain proportion of early infections with "mild" parasites, cerebral malaria is caused by a few distinct highly virulent strains. Considerable variation in parasite virulence, as a major factor of disease severity in malaria, is made possible by the absence of competition between the various parasite strains, arising from weak shared immune responses. The theoretical framework presented in this paper can explain other epidemiological observations, such as the results of interventions with insecticide-impregnated bednets.

Age Factors↗

PubMed1994

Studies on the biological characterization and mitogenic interactions between hepatic stimulator substance and acidic fibroblast growth factor.

During liver regeneration, hepatic stimulator substance (HSS) and acidic fibroblast growth factor (FGF-1) are produced in the liver. These growth factors may be involved in liver growth control but an understanding of their regulatory interactions is limited. To further characterize the mitogenic activity of HSS, we compared its effects with FGF-1 in cells of hepatocyte, non-parenchymal liver epithelial and non-hepatic lineages. Our studies with these cell types demonstrated differences in the mitogenic specificities of HSS and FGF-1. Whereas exposure of primary hepatocytes to epidermal growth factor and HSS synergistically increased DNA synthesis, simultaneous exposure to HSS and FGF-1 resulted in no such effect. Receptor-binding assays showed that HSS did not compete with FGF-1 in binding to FGF-1 receptors on rat primary hepatocytes. Additional immunoblot analysis demonstrated no cross-reactivity between FGF-1 antibodies and HSS. Distinct mitogenic and immunologic properties of HSS and FGF-1 should facilitate further analysis of liver regeneration and hepatic oncogenesis.

Animals↗