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Biomedical subjects

S Mathur

Publications and source records attributed to S Mathur.

At least 73 records · Page 4Linked to original sources
PubMed1991

Epstein Barr virus/complement C3d receptor is an interferon alpha receptor.

Interferon alpha contains a sequence motif similar to the complement receptor type two (CR2/CD21) binding site on complement fragment C3d. Antibodies against a peptide with the CR2 binding sequence on C3d react with a peptide carrying the IFN alpha CR2 binding motif (residues 92-99) and with recombinant IFN alpha. The IFN alpha-derived peptide, as well as recombinant IFN alpha, inhibits C3bi/C3d interaction with CR2 on the Burkitt lymphoma Raji. The direct interaction of IFN alpha and CR2 is inhibited by polyclonal anti-IFN alpha, anti-CR2 and anti-C3d peptide antibodies as well as by C3bi/C3d, EBV coat protein gp350/220 and IFN but not by IFN gamma. [125I]IFN alpha binding to Raji cells is inhibited by polyclonal anti-IFN alpha and anti-CR2 antibodies, by peptides with the CR2 binding motif and partially by C3bi/C3d. Monoclonal anti-CR2 antibody HB5, but not OKB-7, blocks IFN alpha binding to Raji cells. CR2 or CR2-like molecules may therefore be the major IFN alpha receptors on B lymphocytes.

Amino Acid Sequence↗
PubMed1991

Inhibition of acylcoenzyme A: cholesterol acyltransferase activity by PD128O42: effect on cholesterol metabolism and secretion in CaCo-2 cells.

The regulation of cholesterol uptake and secretion by acylcoenzyme A:cholesterol acyltransferase (ACAT) was investigated in the human intestinal cell line, CaCo-2. A new ACAT inhibitor, PD128042 (CI-976), was first characterized. The addition of the fatty acid anilide to membranes prepared from CaCo-2 cells inhibited ACAT activity without altering the activities of HMG-CoA reductase, fatty acid Co-A hydrolase, or triglyceride synthetase. PD128042 was a competitive inhibitor of ACAT with 50% inhibition occurring at a concentration of 0.2 micrograms/mL. When added to the medium of CaCo-2 cells at a concentration of 5 micrograms/mL, PD128042 inhibited oleate incorporation into cholesteryl oleate by 92% and increased oleate incorporation into triglycerides and phospholipids by 51% and 38%, respectively. After incubating CaCo-2 cells with the ACAT inhibitor, the rate of newly synthesized cholesterol decreased by 75% and membranes prepared from these cells contained significantly less HMG-CoA reductase activity. PD128042 significantly decreased the basolateral secretion of newly synthesized cholesteryl esters without affecting the secretion of newly synthesized triglycerides or phospholipids. The inhibitor decreased the esterification of labeled exogenous cholesterol which was taken up by the cell from bile salt micelles. Moreover, after 16 hr of ACAT inhibition, less labeled unesterified micellar cholesterol was associated with the cell. The esterification of cholesterol in CaCo-2 cells plays an integral role in the uptake of cholesterol through the apical membrane and its eventual secretion at the basolateral membrane.

Acyl Coenzyme A↗
PubMed1991

Radioprotection by MPG of mice ovaries exposed to sublethal gamma radiation doses at different postnatal ages.

Female Swiss albino mice were exposed at 1, 3 or 6 weeks of age respectively to sublethal doses (0.6, 1.2 and 2.4 Gy) of gamma radiation in the presence or absence of 2-mercaptopropionylglycine (MPG). Ovaries were histologically examined at different intervals after irradiation and the follicles were counted. Most follicular depletion had occurred already at postirradiation day 1 and the depletion then gradually continued. At day 35 after irradiation a few follicles could still be found in mice exposed at 1 week of age while all follicles were eliminated in mice exposed at 3 and 6 weeks of age. In MPG-treated animals the depletion of follicles was significantly less pronounced and obviously MPG to some degree protected the ovaries from radiation damage.

Age Factors↗
PubMed1991

Poliomyelitis with special reference to immunization status.

One hundred ninety one children below 5 years of age suffering from poliomyelitis were analyzed to find out the immunization status and its correlation with the incidence of poliomyelitis. Effects of age, sex, immunization status and seasonal variation on the morbidity and mortality status were studied. The maximum number of cases were admitted during the months of July (23.6%) and August (23.1%). Of 191 cases, 143 (74.9%) had no immunization and 48 (25.1%) were partially immunized. A total of 155 (81.2%) cases had spinal polio, 23 (12.01%) bulbo-spinal polio, and 13 had (6.8%) bulbar polio. Serious illness (bulbospinal and bulbar type) was more in partially immunized children (25%) as compared to unimmunized children (16.8%). The mortality rate was more than two times higher in the partially immunized (29.6%) as compared to unimmunized children (11.2%). The possible explanation for high mortality in partially immunized children could be due to the adverse effect of OPV which has not been studied so far.

Age Factors↗
PubMed1991

Hepatitis B virus infection and its transmission in preschool children.

In the present study, 2.5% of 367 preschool children has HBsAg positivity. Of 11 mothers who were HBsAg positive during the third trimester of pregnancy, 4 had babies (36.4%) who developed HBsAg positivity by 2.5-3 months of age (vertical transmission). Two babies born of HBsAg negative mothers, with history of jaundice during first trimester, were HBsAg negative. All the relatives of HBsAg positive cases screened were negative for HBsAg.

Child, Preschool↗
PubMed1991

Depletion of ovarian oocytes in sublethally exposed mice to gamma radiation and its modification by 2-mercaptopropionylglycine (MPG).

Adult female Swiss albino mice were exposed to 0.6, 1.2 and 2.4 Gy of 60Co gamma radiations in presence and absence of MPG. Quantitative studies were done in serial sections of ovary at 1, 3, 5, 7, 14 and 35 days after exposure. Primary follicles were found to be most radiosensitive. The depletion in the various types of follicles was checked to some extent by prior administration of MPG, but MPG could not prevent the complete elimination of all types of follicles by the last autopsy interval studied.

Animals↗
PubMed1991

Antigenic differences between the endometrium of women with and without endometriosis.

Serum and peritoneal fluid from 12 women with endometriosis, 4 women with uterine leiomyomata and 6 fertile women without endometriosis (controls) and serum from 4 women with adenomyosis were tested with a passive hemagglutination assay for antibodies against endometrium from all the controls, 8 patients with endometriosis and all patients with uterine leiomyomata and from implants from 8 patients with endometriosis. Serum antibody titers in patients with endometriosis or leiomyomata were significantly higher against endometrial or implant antigens from patients with endometriosis and 2 patients with leiomyomata than those against the controls' endometrium. Peritoneal fluid endometrial antibody titers failed to reflect these antigenic differences. Controls and patients with adenomyosis had low titers of endometrial antibodies in their serum or peritoneal fluid. Antigenic differences appear to exist between the endometrium of patients with endometriosis and that of controls.

Adult↗
PubMed1990

Effect of lovastatin on acyl-CoA: cholesterol O-acyltransferase (ACAT) activity and the basolateral-membrane secretion of newly synthesized lipids by CaCo-2 cells.

Lovastatin, a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity, was used to study the regulation of cholesterol metabolism and the basolateral-membrane secretion of triacylglycerol and cholesterol in the human intestinal cell line CaCo-2. At 0.1 microgram/ml, lovastatin decreased 3H2O incorporation into cholesterol by 71%. In membranes prepared from cells incubated with lovastatin for 18 h, HMG-CoA reductase activity was induced 4-8-fold. Mevalonolactone prevented this induction. In intact cells, lovastatin (10 micrograms/ml) decreased cholesterol esterification by 50%. The reductase inhibitor decreased membrane acyl-CoA:cholesterol O-acyltransferase (ACAT) activity by 50% at 5 micrograms/ml. ACAT inhibition by lavastatin was not reversed by adding excess of cholesterol or fatty acyl-CoA to the assay. Lovastatin, in the presence or absence of mevalonolactone, decreased the basolateral secretion of newly synthesized cholesteryl esters and triacylglycerols. Lovastatin also inhibited the esterification of absorbed cholesterol and the secretion of this newly synthesized cholesteryl ester. Lovastatin is a potent inhibitor of cholesterol synthesis in CaCo-2 cells. Moreover, it is a direct inhibitor of ACAT activity, independently of its effect on HMG-CoA reductase and cholesterol synthesis.

Adenocarcinoma↗
PubMed1990

A comparison of sperm antibody assays.

Cytotoxicity and Immunobead-binding immunoglobulin G assays agreed in 81% of sera from infertile men (n = 173), 74% of sera from their wives, 75% of seminal plasma, and 82% of cervical mucous samples (p less than 0.001; chi 2 analysis of positive and negative results) when tested against sperm from the same donors. Cytotoxic and immunofluorescent IgG antibody results agreed in 79% of sera from men and women, 76% of seminal plasma, and 76% of cervical mucus (p less than 0.001; chi 2 analysis of positive and negative results). Titers or percent binding of sperm by cytotoxicity, hemagglutination, and IgG Immunobead-binding or immunofluorescence assays in serum and secretions of husbands and wives correlated (p less than 0.001). A significantly increased number of positive results was observed in cytotoxic and Immunobead-binding IgG assays when the husbands' and donors' sperm were used rather than donors' sperm alone. On the basis of this study we conclude: (1) that cytotoxicity, Immunobead-binding IgG, and immunofluorescent IgG sperm antibody assays correlate when sperm from the same source are used, (2) that women's isoimmunity to husbands' sperm is associated with their husbands' autoimmunity to sperm irrespective of the assay, and (3) that it is desirable to use sperm from the husbands and nonautoimmune fertile men in these assays.

Adult↗
PubMed1990

Options for elective treatment of portal hypertension in cirrhotic patients in the transplantation era.

We review herein our experience in the management of bleeding esophageal varices in cirrhotic patients and consider our findings in light of the dramatic changes in the treatment of cirrhosis resulting from the more widespread use of orthotopic liver transplantation (OLT). It does not seem realistic, at present, to propose OLT as the only effective treatment of variceal bleeding for a variety of reasons, and there remains a large group of patients who are noncompliant or unsuitable for liver transplantation. We propose that initial bleeding be controlled by endoscopic sclerotherapy, thereby allowing careful evaluation to be made electively. Grade A patients appear to be managed best by a reduced-size portacaval shunt (RPS) with prospects of good survival and few complications. Grade B patients can be managed by either sclerotherapy, RPS, or OLT, depending upon individual circumstances. Grade C patients are best managed by liver transplantation, again with excellent survival. In those grade C patients not deemed suitable for OLT (especially alcoholic patients), long-term endoscopic sclerotherapy is the best option. Changes in patient status may sometimes require revision of the treatment decision.

Adolescent↗
PubMed1990

Changes in sperm antibody test results when spermatozoa are subjected to capacitating conditions.

Cytotoxic and immunobead-binding antibody assays were used to document possible changes in antigenicity after the spermatozoa were subjected in vitro to capacitating conditions. Serum and seminal plasma immunobead-binding immunoglobulin (Ig)A, sperm surface IgG, and IgA, and seminal plasma cytotoxic antibody titers in 26 autoimmune infertile men were decreased against autologous spermatozoa under capacitating conditions. Cytotoxic antibodies and immunobead-binding IgG, IgA, and IgM against husbands' sperm undergoing capacitation, in the cervical mucus of these women, were less than those against uncapacitated sperm. Conversely, sperm antibody levels were increased against the capacitated husbands' sperm in the husbands' serum and wives' cervical mucus, originally testing negative for cytotoxic antibodies against uncapacitated sperm. Antibody levels were unaltered against donors' sperm undergoing capacitation, except for a reduction in titers in the serum of isoimmune wives. The differences in sperm antibody assay results, depending on whether or not spermatozoa are incubated under conditions favoring capacitation, are specific to the husbands' and not to the donors' spermatozoal antigens.

Antibodies↗