Biomedical subjects

S Sengupta

Publications and source records attributed to S Sengupta.

At least 19 recordsLinked to original sources

PubMed1992

Role of adrenergic and cholinergic mediators in salivary phospholipids secretion.

The influence of adrenergic and cholinergic mediators on phospholipid secretion in rat sublingual salivary gland cells maintained in the presence of [3H]choline was investigated. The secretion of [3H]choline-containing phospholipids over 30 min period averaged 1.93% of the total cellular labeled phospholipids in the absence of any mediator, and was enhanced by beta-adrenergic agonist, isoproterenol, to a greater extent than the cholinergic agonists, pilocarpine and carbachol. A 2.9-fold increase in phospholipid secretion occurred with isoproterenol, while pilocarpine and carbachol evoked only 1.3-fold increase. The effect of isoproterenol was inhibited by alprenolol and that of pilocarpine and carbachol by atropine. In contrast to pilocarpine and carbachol, the enhanced phospholipid secretion due to isoproterenol was accompanied by an increase in cAMP concentration. The secretion of phospholipids was also stimulated by dibutyryl-cAMP and the protein kinase C activator, phorbol myristate acetate, but not by 4 alpha-phorbol 12,13-didecanoate which does not activate protein kinase C. Furthermore, the effects of dibutyryl-cAMP and phorbol myristate acetate were additive. The phospholipids secreted in response to isoproterenol exhibited a 52% decrease in lysophosphatidylcholine, while those secreted in response to pilocarpine and carbachol showed a 21-23% lower content of phosphatidylcholine, and were enriched in lysophosphatidylcholine (2.6-2.8-fold) and sphingomyelin (1.5-1.6-fold). The results indicate that salivary phospholipid secretion remains mainly under beta-adrenergic regulation, while the phospholipid makeup of the secretion is under cholinergic control.

Adrenergic beta-Agonists↗

PubMed1992

Control of gastric mucus phospholipid content and composition by cholinergic and adrenergic mediators.

1. The secretion of choline-containing phospholipids by gastric mucosal cells in response to neural mediators was investigated using beta-adrenergic and cholinergic agents. 2. A 2.7-fold increase in phospholipid secretion occurred with isoproterenol, while pilocarpine evoked 1.4-fold increase and the effects were inhibited by the respective antagonists. 3. The phospholipid secretory responses were stimulated by dibutyryl-cAMP and phorbol myristate acetate (PMA), but not by 4 alpha-phorbol-12,13-didecanoate which does not activate protein kinase C. The effects of dibutyryl-cAMP and PMA were additive, the the PMA induced phospholipid secretion was inhibited by a protein kinase C inhibitor, tetracaine. 4. The phospholipids secreted in response to isoproterenol showed a 2.1-fold decrease in lysophosphatidylcholine, while those secreted in response to pilocarpine were enriched 2.3-fold in lysophosphatidylcholine, and 1.5-fold in sphingomyelin, and showed 23% lower content of phosphatidylcholine. 5. The results suggest that cholinergic and beta-adrenergic mediators participate in defining the gastric mucus phospholipid content and composition, and hence influence the mucosal protective capability.

Adrenergic beta-Agonists↗

PubMed1992

Adrenergic and cholinergic regulation of gastric mucus phospholipid secretion.

The influence of adrenergic and cholinergic agonists on phospholipid secretion in gastric mucosal cells maintained in the presence of [3H]choline was investigated. The secretion of [3H]choline phospholipids over a 30-min period averaged 1.98% of the total cellular labeled phospholipids in the absence of any mediator and was enhanced by the beta-adrenergic agonist isoproterenol to a greater extent than by the cholinergic agonist pilocarpine. A 2-fold increase in phospholipid secretion was achieved with isoproterenol, whereas pilocarpine produced a 1.3-fold increase. The stimulatory effect of isoproterenol was inhibited by alprenolol, and that of pilocarpine by atropine. The phospholipids secreted in response to isoproterenol showed a 30% decrease in lysophosphatidylcholine, whereas a 2.1-fold enrichment in this phospholipid occurred with pilocarpine. The results demonstrate the involvement of neural mediators in the regulation of phospholipid secretion in gastric mucus.

Alprenolol↗

PubMed1992

Phaseolus vulgaris L. var. HUR 15--a potential indigenous source for commercial PHA preparation.

Mitogenic potential of the partially purified lectin from P. vulgaris isolated by ammonium sulphate precipitation was assessed by lymphocyte transformation test (LTT) and was compared with three commercially available phytohemagglutinins (PHA). The blast inducing capacity and mitotic index analysis revealed that this preparation has potential to be used in the indigenous commercial production of PHA which is routinely used for human chromosomal studies from the peripheral blood culture at, at present, is imported.

Dose-Response Relationship, Drug↗

PubMed1992

Network information security in a phase III Integrated Academic Information Management System (IAIMS).

The developing Integrated Academic Information System (IAIMS) at Columbia-Presbyterian Medical Center provides data sharing links between two separate corporate entities, namely Columbia University Medical School and The Presbyterian Hospital, using a network-based architecture. Multiple database servers with heterogeneous user authentication protocols are linked to this network. "One-stop information shopping" implies one log-on procedure per session, not separate log-on and log-off procedures for each server or application used during a session. These circumstances provide challenges at the policy and technical levels to data security at the network level and insuring smooth information access for end users of these network-based services. Five activities being conducted as part of our security project are described: (1) policy development; (2) an authentication server for the network; (3) Kerberos as a tool for providing mutual authentication, encryption, and time stamping of authentication messages; (4) a prototype interface using Kerberos services to authenticate users accessing a network database server; and (5) a Kerberized electronic signature.

Computer Communication Networks↗

PubMed1992

Control of salivary phospholipid content and composition.

The mediation of phospholipid secretion in rat sublingual salivary gland cells maintained in the presence of [3H]choline was investigated. The secretion of [3H]choline-containing phospholipids was enhanced by beta-adrenergic agonist, isoproterenol, to a greater extent than the cholinergic agonist carbachol. A 2.9-fold increase in phospholipid secretion occurred with isoproterenol, while carbachol evoked only about 1.3-fold increase. In contrast to carbachol, the enhanced phospholipid secretion due to isoproterenol was accompanied by an increase in cAMP concentration. The secretion of phospholipids was also stimulated by dibutyryl-cAMP and the protein kinase C activator, phorbol myristate acetate, but not by 4 alpha-phorbol 12, 13-didecanoate which does not activate protein kinase C. Furthermore, the effects of dibutyryl-cAMP and phorbol myristate acetate were additive. The phospholipids secreted in response to isoproterenol exhibited a 52% decrease in lysophosphatidylcholine, while those secreted in response to carbachol showed a 23% lower content of phosphatidylcholine, and were enriched in lysophosphatidylcholine (2.8-fold) and sphingomyelin (1.4-fold). The results suggest that salivary phospholipid secretion remains mainly under beta-adrenergic control, while the phospholipid makeup is under cholinergic regulation.

Animals↗

PubMed1992

Effect of hydrogen peroxide on mammalian chromatin: electron microscopic studies.

Chromatins purified from rat liver as well as from cultured Chinese hamster V79 cells were treated with hydrogen peroxide in presence of iron in vitro. When examined in a transmission electron microscope, chromatins from both the sources were found to lose the native morphology. There were evidences of aggregation of the chromatin fibers. This could be due to DNA-protein and DNA interstrand crosslinking induced by Fenton reaction.

Animals↗

PubMed1992

Plasma viremia in human immunodeficiency virus infection: relationship to stage of disease and antiviral treatment.

Quantitative culture of human immunodeficiency virus (HIV) was performed on 121 plasma samples from 76 HIV-infected individuals to determine the sensitivity of the assay at different stages of disease and to measure the effect of antiviral therapy on plasma viremia. Plasma virus was detected in 49 of 76 (64%) of patients, primarily those with AIDS and AIDS-related complex (36 of 38) versus asymptomatic subjects (13 of 38) (p less than 0.001, chi 2). Similarly, plasma cultures were more often positive in patients with less than 250 CD4+ T cells per microliter (38 of 40) than in those with greater than 250 CD4+ T cells per microliter (11 of 36) (p less than 0.001, chi 2). Plasma virus cultures were also more likely to be positive in patients with detectable serum p24 antigen (24 of 26) than in those without detectable p24 antigen (25 of 50) (p = 0.0023, chi 2). An effect of zidovudine (ZDV) treatment on plasma viremia was seen in a comparison of treated and untreated patients with less than 250 CD4+ T cells per microliter. Geometric mean titers of plasma viremia from 16 patients treated with ZDV for more than 3 months were significantly lower than titers from 24 untreated patients (10(1.3) versus 10(2.1), p less than 0.05, Student's t test. A comparison of pre- and posttherapy titers in 33 patients receiving antiviral treatment showed that plasma virus was not detectable at either time in 17 patients; there was a fall in plasma virus titer in 12; and titers were unchanged or increased in 4. In patients with advanced disease, plasma viremia is a potential marker of antiviral drug activity.

AIDS-Related Complex↗

PubMed1991

Inhibition of gastric mucosal laminin receptor by Helicobacter pylori lipopolysaccharide.

Laminin receptor was isolated from gastric epithelial cell membrane by the procedure involving membrane solubilization with octylglucoside followed by affinity chromatography on laminin-coupled Sepharose. The receptor protein, eluted from the matrix with cation-free EDTA buffer, yielded on SDS-PAGE a single 67kDa band. After radioiodination, the protein was incorporated into liposomes which displayed specific affinity toward the laminin-coated surface. The binding of liposomal receptor to the laminin-coated surface was inhibited by lipopolysaccharide from H.pylori. The inhibitory effect was proportional to the concentration of lipopolysaccharide up to 50 micrograms/ml at which point a 96% decrease in the receptor binding occurred. It is suggested that a similar process may account for the loss of mucosal integrity in the pathogenesis of H. pylori associated gastric disease.

Animals↗

PubMed1991

Purification and characterisation of a beta-glucosidase (cellobiase) from a mushroom Termitomyces clypeatus.

A beta-glucosidase with cellobiase activity was purified to homogeneity from the culture filtrate of the mushroom Termtomyces clypeatus. The enzyme had optimum activity at pH 5.0 and temperature 65 degrees C and was stable up to 60 degrees C and within pH 2-10. Among the substrates tested, p-nitrophenyl-beta-D-glucopyranoside and cellobiose were hydrolysed best by the enzyme. Km and Vm values for these substrates were 0.5, 1.25 mM and 95, 91 mumol/min per mg, respectively. The enzyme had low activity towards gentiobiose, salicin and beta-methyl-D-glucoside. Glucose and cellobiose inhibited the beta-D-glucosidase (PNPGase) activity competitively with Ki of 1.7 and 1.9 mM, respectively. Molecular mass of the native enzyme was approximated to be 450 kDa by HPLC, whereas sodium dodecyl sulphate polyacrylamide gel electrophoresis indicated a molecular mass of 110 kDa. The high molecular weight enzyme protein was present both intracellularly and extracellularly from the very early growth phase. The enzyme had a pI of 4.5 and appeared to be a glycoprotein.

Basidiomycota↗

PubMed1991

Inhibition of bovine gingival laminin receptor by bacterial lipopolysaccharide.

A laminin receptor was isolated from bovine gingival epithelial-cell membrane. After solubilization with octylglucoside, the receptor was subjected to affinity chromatography on laminin-coupled Sepharose and eluted with cation-free EDTA buffer yielding on SDS-PAGE a 67 kDa protein band. After radioiodination, the protein was incorporated into liposomes which displayed specific affinity towards laminin-coated surfaces, as well as to tooth cementum. The binding of receptor protein to cementum was inhibited by lipopolysaccharide from Bacteroides gingivalis. Preincubation of cementum with the lipopolysaccharide decreased the binding of the liposomal laminin-receptor preparation by 35.8%, while a 59.2% decrease in binding occurred when the lipopolysaccharide was preincubated with the receptor, suggesting that the lipopolysaccharide interfered with the laminin binding site on the receptor. The results demonstrate the existence of a specific gingival cell-surface laminin receptor, show that it is capable of binding to cementum, and provide evidence for the disruption of this process by bacterial lipopolysaccharide. This mechanism may account for the loss of gingival attachment in the pathogenesis of periodontal disease.

Affinity Labels↗

PubMed1991

Identification of laminin receptor in gingival tissue and its interaction with tooth cementum laminin.

1. A gingival epithelial cell surface receptor for laminin was isolated from bovine gingival tissue by affinity chromatography on laminin. 2. The protein bound by the affinity matrix from octylglucoside extracts of gingival membrane preparation eluted from the column with the cation-free buffer containing EDTA, and exhibited a mol. wt of 67 kDa. 3. The 67 kDa protein following radioiodination was incorporated into liposomes, which showed a specific affinity towards laminin-coated surfaces, as well as to the tooth cementum. 4. The results provide for the first time evidence for the existence of a gingival cell surface laminin receptor, and indicate that the maintenance of the cemento-epithelial junction involves the interaction between the cementum laminin and its receptor on gingival epithelium.

Animals↗

PubMed1991

Adrenergic and cholinergic regulation of phospholipid release in sublingual salivary gland in vitro.

1. The role of adrenergic and cholinergic mediators in the regulation of salivary phospholipid secretion was investigated using rat sublingual acinar cells maintained in the presence of [3H]choline. 2. The release of [3H]choline containing phospholipids was enhanced by beta-adrenergic agonist, isoproterenol to a greater extent than the cholinergic agonist, pilocarpine. 3. The effect of isoproterenol on phospholipid release was observed even after 5 min and by 30 min a 1.7-fold increase in secretion occurred, whereas pilocarpine evoked 1.2-fold increase by 30 min with no discernible effect in 5 min. The isoproterenol effect was blocked by alprenolol, and an inhibition of pilocarpine effect was observed with atropine. 4. In the absence of mediators, 82% of secreted labeled phospholipids were represented by phosphatidylcholine (PC), 4.3% by lysophosphatidylcholine (LPC) and 12.1% by sphingomyeline (Sph), those secreted in the presence of isoproterenol showed significantly lower (37%) content of LPC, while those secreted in response to pilocarpine were substantially richer in LPC (2.5 times) and Sph (27%), and contained less (17%) PC. 5. The results provide first evidence for the involvement of adrenergic and cholinergic mediators in the regulation of salivary phospholipid secretion.

Alprenolol↗

PubMed1991

Detection and quantification of human immunodeficiency virus RNA in patient serum by use of the polymerase chain reaction.

Human immunodeficiency virus (HIV) RNA was detected and quantified in the serum of HIV-seropositive individuals using the polymerase chain reaction (PCR) and a nonisotopic enzyme-linked affinity assay. Of 55 HIV-infected patients who were not receiving therapy, serum HIV RNA was detected in 9 of 19 who were asymptomatic, 11 of 16 with AIDS-related complex (ARC), and 18 of 20 with AIDS, with copy numbers ranging from 10(2) to greater than or equal to 5 x 10(4) 200 microliters of serum based on a relationship between absorbance and known copy number of gag gene RNA. Linear regression analysis demonstrated a correlation between infectious titer in 42 patient sera cocultured with donor peripheral blood mononuclear cells (PBMC) and PCR product absorbance (r = .70, P less than .01). Serum HIV RNA detected by PCR also correlated with serum p24 antigen positivity, CD4 counts less than 400/mm3, and the presence of HIV-related symptoms or disease. Quantification of infectious HIV RNA in cell-free serum by PCR may be useful as a marker for for disease progression or in monitoring antiviral therapy.

AIDS-Related Complex↗

PubMed1991

Control of methionine biosynthesis in Escherichia coli K12: a closer study with analogue-resistant mutants.

Control of methionine biosynthesis in Escherichia coli K12 was reinvestigated by using methionine-analogue-resistant mutants. Norleucine (NL) and alpha-methylmethionine (MM) were found to inhibit methionine biosynthesis directly whereas ethionine (Et) competitively inhibited methionine utilization. Adenosylation of Et to generate S-adenosylethionine (AdoEt) by cell-free enzyme from E. coli K12 was demonstrated. Tolerance of increasing concentrations of NL by E. coli K12 mutants is expressed serially as phenotypes NLR, NLREtR, NLRMMR and finally NLREtRMMR. All spontaneous NLR mutants had a metK mutation, whereas NTG-induced mutants had mutations in both the metK and metJ genes. The kinetics of methionine adenosylation by the E. coli K12 cell-free enzyme were found to be similar to those reported for the yeast enzyme, showing the typical lag phase at low methionine concentration and disappearance of this phase when AdoMet was included in the incubation mixture. NL extended the lag phase, and lowered the rate of subsequent methionine adenosylation, but did not affect the shortening of the lag phase of adenosylation by AdoMet.

Adenosine↗

PubMed1991

Role of adrenergic and cholinergic mediators in gastric mucus phospholipid secretion.

The role of adrenergic and cholinergic mediators in phospholipid secretion by gastric mucosal cells maintained in the presence of [3H]choline was investigated. The secretion of [3H]choline phospholipids over 30 min period averaged 1.98% of the total cellular labeled phospholipids in the absence of any mediator, and was enhanced by beta-adrenergic agonist, isoproterenol, to a greater extent than the cholinergic agonist, pilocarpine. A 2-fold increase in phospholipid secretion was achieved with isoproterenol, while pilocarpine evoked 1.3-fold increase. The stimulatory effect of isoproterenol was inhibited by alprenolol and that of pilocarpine by atropine. The phospholipids secreted in response to isoproterenol exhibited a 30% decrease in lysophosphatidylcholine, while 2.1-fold enrichment in this phospholipid occurred with pilocarpine. The results, for the first time, demonstrate the involvement of neural mediators in the regulation of phospholipid secretion in gastric mucus.

Alprenolol↗

PubMed1991

Chlamydia trachomatis in pelvic inflammatory disease.

C. trachomatis seems to be an important causative organism of pelvic inflammatory disease (PID) as C. trachomatis antigen and/or antibody was found in 234 (69.85%) of 335 patients clinically diagnosed to have PID. Antigen was detected in the lower genital tract of 118 (35.22%) patients whereas IgG antibody was present in 188 (56.11%), of whom 89 (47.34%) had a high titre. Repeat testing of sera of 37 patients showed a rise in antibody titre in 18 (40%). As the success rate of therapy for PID with doxycycline was found to be 80 per cent, early diagnosis and treatment may be recommended to prevent further complications of PID.

Adult↗

PubMed1991

Characterization of gingival epithelium epidermal growth factor receptor.

The binding characteristics of gingival epithelium epidermal growth factor (EGF) receptor were investigated using epithelial cell membranes from bovine gingiva. The binding of [125I]EGF was found to be time and protein concentration dependent, reversible, and specific. Unlabeled EGF competed for [125I]EGF binding with IC50 of 0.25nM and maximum displacement of 93% at 0.81nM. Scatchard analysis of the binding data inferred the presence of two binding sites, one of high affinity (Kd = 3.3 nM and Bmax = 47.3fmol/mg protein) and the other of a low affinity (Kd = 1.6 microM and Bmax = 1.9pmol/mg protein). Crosslinking of [125I]EGF to gingival membranes followed by polyacrylamide gel electrophoresis and autoradiography revealed a receptor protein of 170kDa.

Animals↗