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Biomedical subjects

S Chatterjee

Publications and source records attributed to S Chatterjee.

At least 109 records · Page 6Linked to original sources
PubMed1993

Physical and motor fitness level of Indian school-going boys.

A cross-sectional study of physical and motor fitness measurements was undertaken on 629 healthy Indian (Bengalee) school-going boys of 9-18 years. The study brought to light gradual increase in physical and motor fitness measurements with the advancement of age except physical fitness score. Major increments were recorded between 13 and 15 years of age. All the fitness test scores showed significant positive correlations with age, height and weight but Dash, Shuttle Run and PFI showed significantly negative relationship. Indian boys of the present study were superior in Sit and Reach and inferior in Vertical Jump to the Belgian boys of comparable ages. These boys showed higher values in Vertical Jump than American boys after the age of 13. Dash and Shuttle Run test scores of Indian boys fall between 15th to 25th and 30th to 45th percentiles of American Standard respectively. Besides, American boys are superior in Grip Strength to Indian boys. Percentile values of physical and motor fitness test scores of Indian (Bengalee) boys are, therefore, useful for determining their present fitness status and potentiality in that particular community for specific sports activity.

Adolescent↗
PubMed1993

Effect of pH adjustment of bupivacaine on onset and duration of epidural anaesthesia.

The effect of pH adjustment of bupivacaine on onset and duration of sensory and motor block was studied in 45 patients undergoing lower abdominal and lower limb surgery. The study was done in 3 groups with the mean pH adjustment of 5.85, 7.14 and 7.21. Each patient was given 30 ml of 0.4% pH adjusted bupivacaine solution in epidural space. Onset of sensory block and duration were noticed by pin-prick method while motor block was observed by asking the patient to raise the thigh. It was observed that increase in pH of bupivacaine solution quickens the onset of sensory and motor block and increases the overall duration of neural blockade.

Adolescent↗
PubMed1993

Herpes simplex encephalitis: a diagnostic and therapeutic reapprisal.

Herpes Simplex Encephalitis (HSE) appears to be underdiagnosed in India, though viral encephalitides constitutes an important entity with significant morbidity. With an upsurge in AIDS, HSE may perhaps emerge as an important opportunistic infection in future. We discuss the clinical features and laboratory evaluation of nine cases of HSE seen in the last 12 years at our center. Diagnosis was established by brain biopsy in one, virological studies in six and at autopsy in three. Immunocytochemically viral antigens could be localized in 4 biopsied/autopsied brain tissue and in CSF cells on a cytospin preparation in one. This has facilitated rapid diagnosis in our cases. Virus isolation was successful in two. Three subjects were treated with acyclovir and all survived with variable morbidity. Four patients expired and none of them had received any specific antiviral drugs. Rapid diagnosis and early treatment with acyclovir has been highlighted.

Acyclovir↗
PubMed1993

Acromegaly.

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Acromegaly↗
PubMed1993

Neutral sphingomyelinase.

Although we have accumulated few data that would definitely designate the role of N-SMase in modern cell biology, current evidence indicates that N-SMase may play a central role in signal transduction (Fig. 7). Biomodulators such as hormones, antibiotics, drugs, growth factors, and lipoproteins may interact with N-SMase either directly or in combination with other components (receptors) on the cell surface. The cell surface topology would provide easy access for such interactions. According to our hypothetical model shown in Fig. 7, activation of N-SMase via biomodulators, e.g., TNF-alpha, leads to the mobilization of cell surface cholesterol to the interior of the cell. We speculate that this process may be facilitated by sterol carrier proteins. This phenomenon may alter the lipid bilayer and make N-SMase accessible to its substrate, sphingomyelin. Ceramide released as a consequence of N-SMase reaction would then carry out various biological phenomena, such as cell proliferation and differentiation. Cholesterol on the other hand, may undergo oxidation and inhibit HMG-CoA reductase activity; it may also be utilized by ACAT to form cholesteryl esters. A decrease in cell membrane cholesterol levels may stimulate LDL receptor activity and LDL receptor recycling and/or synthesis. In contrast, inactivation or decreased activity of N-SMase, as in the case of gentamicin-treated cells, may have the opposite effect, i.e., decreased LDL receptor activity and decreased cholesteryl ester synthesis. Thus, N-SMase may indirectly modulate cholesterol metabolism in cells independent of LDL. It can also modify LDL, allowing its rapid uptake and foam cell formation in macrophages. We can safely conclude that N-SMase action may be required to carry out a myriad of important cellular functions either directly or by cholesterol mobilization, or generation of ceramide, ceramide-1-phosphate, and sphingoid bases. The present data support the view that N-SMase action may initiate signal transduction for such biomodulators as growth factors, lipoprotein, and hormones.

Animals↗
PubMed1992

Poly-(ADP-ribose) polymerase partially contributes to target cell death triggered by cytolytic T lymphocytes.

We hypothesized that CTL-induced target cell (TC) death is partially due to processes that follow the DNA damage in target cells and include the activation of poly-ADP-ribose transferase (PADPRT) by DNA strand breaks. According to this model, the activated PADPRT is expected to deplete NAD, ATP, and to contribute to the TC death. We used inhibitors of PADPRT and a PADPRT-deficient cell mutant, as well as other nucleated TC and SRBC to test the role of PADPRT in CTL-induced cytotoxicity. It is found that inhibitors of PADPRT (3-aminobenzamide, benzamide (aromatic amides)) and nicotinamide all inhibit the CTL-mediated lysis of both Ag-specific TC and of Ag-nonbearing TC. The effect of PADPRT inhibitors was not due to inhibition of the lethal hit delivery by CTL, because in parallel control experiments, the same inhibitors did not interfere with CTL-induced lysis of SRBC, cells that are devoid of nuclei and PADPRT. Moreover, the effect of inhibitors of PADPRT did not affect earlier stages of lethal hit delivery because 3-aminobenzamide and benzamide did not interfere with CTL-induced DNA fragmentation in TC at concentration which protected TC lysis. Importantly, a PADPRT-deficient cell line was also much more resistant to CTL-induced lysis as tested in retargeting (4 and 8 h) assays; this was expected if activation of PADPRT is indeed involved in TC death. Control experiments reveal that the relative resistance of the PADPRT-deficient cell mutant to CTL-induced lysis was not related to its impaired ability to form conjugates and to trigger CTL (as tested in granule exocytosis assay). In addition, PADPRT-deficient cells were as susceptible to CTL-induced DNA fragmentation as were the control cells; yet, they were resistant to CTL-induced 51Cr-release. Control cells and PADPRT-deficient mutant were equally susceptible to antibody+C'-mediated lysis. Our data support the view that the activation of PADPRT can contribute to the CTL-induced cytolysis of some TC, but is not involved in lysis of other TC, as evidenced by the ability of CTL to efficiently lyse SRBC. These data suggest that there could be multiple molecular pathways of TC death in CTL-mediated cytotoxicity and the relative contribution of PADPRT and/or other enzymes will reflect the individual make-up of a particular TC.

Amides↗
PubMed1992

Dual-target inhibition of HIV-1 in vitro by means of an adeno-associated virus antisense vector.

An adeno-associated virus vector encoding an antisense RNA was used to transduce stable intracellular resistance to human immunodeficiency virus-1 (HIV-1) in human hemopoietic and non-hemopoietic cell lines. The antisense targets are present in all HIV-1 transcripts and include the TAR sequence, which is critical for transcription and virus replication, and the polyadenylation signal. Cell lines expressing antisense RNA showed up to 95 percent inhibition of gene expression directed by the HIV-1 long terminal repeat and greater than 99 percent reduction in infectious HIV-1 production, with no detectable cellular toxicity. Because of their efficient transcription and inability to recombine with HIV-1, adeno-associated virus vectors represent a promising form of anti-retroviral gene therapy.

Base Sequence↗
PubMed1992

Inhibition of SH2 domain/phosphoprotein association by a nonhydrolyzable phosphonopeptide.

Using the association between the pp60c-src/polyoma virus middle T antigen (mT) complex and phosphatidylinositol 3'-kinase (PI 3-kinase) as a prototype for phosphoprotein-SH2 domain interactions, we tested whether a nonhydrolyzable phosphonopeptide would inhibit association. (Phosphonomethyl)-phenylalanine (Pmp) is a nonnatural analogue of phosphotyrosine in which the > C-O-PO3H2 moiety is replaced by > C-CH2-PO3H2. We synthesized a 13 amino acid phosphonopeptide (mT-Pmp315), a related phosphopeptide (mT-pY315), and an unmodified sequence (mT-Y315), all corresponding to the pp60c-src-phosphorylated site of the mT which is within a YMXM motif common to proteins that bind to and activate PI 3-kinase. Only the phosphonopeptide persistently blocked the in vitro association of the baculovirus-expressed pp60c-src/mT complex with cytosolic PI 3-kinase activity. Sustained inhibition of association by the phosphopeptide required the additional presence of vanadate, a potent protein tyrosine phosphatase (PTPase) inhibitor. The phosphopeptide and L-phosphonopeptide bound tightly (KD approximately 10-20 nM) and specifically to isolated SH2 domains of PI 3-kinase p85, demonstrating that the mechanism of inhibited association is competitive binding to PI 3-kinase SH2 domains. We conclude that the appropriate phosphonopeptide sequence inhibits the interaction between a tyrosine-phosphorylated protein and a cognate SH2 domain-containing protein and is resistant to the actions of PTPases. Proteolytically stable phosphonopeptide derivatives should be useful inhibitors of protein-protein interactions when introduced into cells and may provide a basis for the rational design of a new class of chemotherapeutic agent.

Amino Acid Sequence↗
PubMed1992

Glycosphingolipids: the putative receptor for Staphylococcus aureus enterotoxin-B in human kidney proximal tubular cells.

We have investigated the binding of 125I-staphylococcal enterotoxin-B (SEB) in cultured human proximal tubular cells. We found that the binding of 125I-SEB to PT cells was time and concentration dependent and competitively inhibited by antibody against SEB. Preincubation of cells with trypsin and neuraminidase or with fetuin did not significantly impair the binding of 125I-SEB to such cells. In contrast, treatment with endoglycoceramidase completely inhibited the binding of 125I-SEB to cells. Neutral glycosphingolipids exerted a concentration-dependent inhibition of 125I-SEB binding to such cells, maximum inhibition (96% compared to control) occurred upon incubation of PT cells with neutral glycosphingolipids. Taken together, our studies indicate that SEB specifically binds to a neutral glycosphingolipid in PT cells. In contrast, staphylococcal enterotoxin-A and toxic shock toxin (TST-1) are bound to a protein in such cells.

Bacterial Toxins↗
PubMed1992

Purification of uridine diphosphate-galactose:glucosyl ceramide, beta 1-4 galactosyltransferase from human kidney.

A galactosyltransferase that transfers galactose from UDP-galactose to glucosylceramide was purified 440-fold to apparent homogeneity from normal human kidney "buffy coat" preparation employing detergent extraction, ultrafiltration, and Sepharose Q column chromatography. On reducing and nonreducing gels, the enzyme resolved into two bands with apparent molecular weights on the order of 60,000 and 58,000, respectively. The activity of the enzyme was also associated with these two bands following separation on polyacrylamide gels. Analytical isoelectric focusing revealed that the pI of this enzyme is approximately 4.55. Product characterization and substrate specificity studies employing chromatography, enzymatic digestion with various glycosidases, and use of a variety of glycosphingolipid substrates revealed that the major product synthesized by this enzyme was Cer1-1 beta Glc4-1Gal, and Cer1-1 beta Glc was the preferred substrate. Digestion of the 60- and 58-kDa proteins with Staphylococcus aureus (V-8) protease revealed at least six peptides having identical electrophoretic migration. This finding suggests that the two proteins may be related to each other. Western immunoblot assays revealed that the antibody against UDP-galactose:GlcCer, beta 1-4 galactosyltransferase (GalT-2) but not galactosyltransferase UDP-Gal:N-acetyl-D-glucosaminyl-glycopeptide 4-beta-D-galactosyltransferase (EC 2.4.1.38) (B-GT) immunoprecipitated (recognized) the kidney GalT-2. In contrast, antibody against B-GT did not immunoprecipitate GalT-2. Thus our data indicate that GalT-2 and B-GT are two distinct enzymes. The availability of the enzyme GalT-2 and corresponding antibody will allow functional studies in the near future.

Blotting, Western↗
PubMed1992

YMXM motifs of IRS-1 define substrate specificity of the insulin receptor kinase.

Of 34 tyrosine residues in insulin receptor substrate 1 (IRS-1), 14 are adjacent to acidic residues, suggesting that they might be phosphorylation sites. Synthetic peptides corresponding to sequences surrounding these tyrosines were used as substrates of the insulin receptor kinase. Surprisingly six of these, each within YMXM motifs, were phosphorylated with greatest efficiency (Km, 24-92 microM; kcat/Km, 0.6-2.1 x 10(4) M-1.sec-1). Substituted YMXM peptides revealed a strong preference of the insulin receptor kinase for methionine at Y + 1 and Y + 3 positions. When phosphorylated, related YMXM sequences are recognition motifs for binding to proteins with src-homology (SH2) domains. The combined hydrophobic and flexible nature of methionine side chains adjacent to the targeted tyrosines provides a versatile contact for recognition by diverse proteins involved in signal transduction.

Amino Acid Sequence↗
PubMed1992

Role of oxidized human plasma low density lipoproteins in atherosclerosis: effects on smooth muscle cell proliferation.

The effects of oxidized human plasma low density lipoproteins (Ox-LDL) on the proliferation of cultured aortic smooth muscle cells was studied, employing viable cell counting, [3H] thymidine incorporation into DNA, and the release of lactate dehydrogenase (LDH) into the medium. Oxidized LDL (prepared by incubation of LDL with copper sulfate) exerted a concentration-dependent stimulation (2 fold, compared to control) of aortic smooth muscle cell proliferation at low concentrations (0.1 micrograms-10 micrograms/ml medium). On the other hand, at high concentrations (25-200 micrograms/ml), Ox-LDL produced a pronounced decrease in viable cells, a decrease in the incorporation of [3H] thymidine into DNA, and an increase in the release of LDH in the medium. In this report, the previously postulated biological roles of oxidized-LDL in atherosclerosis are discussed in view of these findings.

Arteriosclerosis↗