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Biomedical subjects

C Singh

Publications and source records attributed to C Singh.

At least 19 recordsLinked to original sources
PubMed1992

Immunosuppression in vivo by a soluble form of the CTLA-4 T cell activation molecule.

In vitro, when the B7 molecule on the surface of antigen-presenting cells binds to the T cell surface molecules CD28 and CTLA-4, a costimulatory signal for T cell activation is generated. CTLA4Ig is a soluble form of the extracellular domain of CTLA-4 and binds B7 with high avidity. CTLA4Ig treatment in vivo suppressed T cell-dependent antibody responses to sheep erythrocytes or keyhole limpet hemocyanin. Large doses of CTLA4Ig suppressed responses to a second immunization. Thus, costimulation by B7 is important for humoral immune responses in vivo, and interference with costimulation may be useful for treatment of antibody-mediated autoimmune disease.

Abatacept↗
PubMed1992

Hypolipidemic activity of Achyranthus aspera Linn in normal and triton induced hyperlipemic rats.

The alcoholic extract of A. aspera, at 100 mg/kg dose lowered serum cholesterol (TC), phospholipid (PL). triglyceride (TG) and total lipids (TL) levels by 60, 51, 33 and 53% respectively in triton induced hyperlipidemic rats. The chronic administration of this drug at the same doses to normal rats for 30 days, lowered serum TC, PL, TG and TL by 56, 62, 68 and 67% respectively followed by significant reduction in the levels of hepatic lipids. The faecal excretion of cholic acid and deoxycholic acid increased by 24 and 40% respectively under the action of this drug. The possible mechanism of action of cholesterol lowering activity of A. aspera may be due to rapid excretion of bile acids causing low absorption of cholesterol.

Animals↗
PubMed1991

Lead-induced fetal nephrotoxicity in iron-deficient rats.

Lead administration (250, 500, 1000, and 2000 ppm, as lead acetate) in drinking water during fetal development (from 15 to 20 days of gestation), in normal and iron-deficient pregnant rats, revealed dose-dependent increases in the lead content of maternal blood that was more marked in iron-deficient animals. The placentae and fetuses did not show a dose-dependent increase in lead content. Lead administration revealed dose-dependent hydropic degeneration of renal proximal cells in the fetuses. The highest dose (2000 ppm lead) and iron deficiency exhibited more lead accumulation in maternal blood, placentae, and fetuses, and maximum pathologic changes in the fetal kidney when compared with the other doses and also with the fetuses of dams not deficient in iron.

Animals↗
PubMed1990

Continuous-variable quantification of dermatoglyphic whorl patterns: a statistical study of angular measurements.

Core(s) and triradii of dermatoglyphic whorl patterns were joined together to form triangles. Base angles of these triangles were measured (in degrees). The tangent angle at the lower edge of a ridge crossing the core-triradius line was also measured in degrees on each side of the whorl. Significant differences and similarities of these angles were investigated for unrelated Caucasian males and females by the use of Student's t- and Pearson's r-tests. Angular findings were related to the corresponding information provided by ridge counts. Similarities and differences between males and females are described.

Dermatoglyphics↗
PubMed1990

Studies on the antiviral activity of inorganic heteropolyanions against Semliki forest virus in vivo and vaccinia virus in vitro.

Seven new inorganic heteropolyanions were tested for their antiviral activity. One of these, sodium 12-tungstoborate, was found to protect mice from Semliki forest virus and mouse embryo fibroblast monolayers from vaccinia virus infections. In mice these heteropolyanions exhibited no synergistic antiviral activity with the interferon inducing mycoviral double-stranded RNA.

Animals↗
PubMed1989

The antioxidants as protectors of host stress organ injury in mice infected with Plasmodium berghei.

A study has been made of counteracting the stress organ injury in Plasmodium infection by means of antioxidants on the premise that free radicals are responsible for causing the injury to stress organs. This was evidenced by drastically altered biochemical parameters in liver and spleen of the host in terms of elevated levels of lipid peroxides and xanthine oxidase (XO) activity, and a fall in superoxide dismutase activity coupled with other drastic biochemical changes. The cardinal factor responsible for the above was considered to be XO which engenders free radicals purportedly responsible for the stress organ (biochemical) injury. Results demonstrate a lowering of lipid peroxide levels, xanthine oxidase activity, liver weight and modulation of protein level in liver of the host (mouse) in Plasmodium infection when treated with catechin, glutathione and propylgallate.

Animals↗
PubMed1989

Zinc protects testicular injury induced by concurrent exposure to cadmium and lead in rats.

The effect of coexposure to lead and cadmium (each 50 ppm alone and 25 ppm in combination) on the testes of rats and the preventive role of zinc (50 ppm) was investigated by administering these metals through drinking water. Male weaned albino rats were exposed to these metals for 120 days. Testicular histology, sperm counts and sperm motility were studied in these rats. The animals coexposed to lead and cadmium exhibited much more pronounced pathological changes and reduced sperm counts compared to the animals exposed to either of the metals alone. Zinc supplementation to the lead + cadmium exposed rats revealed the protective effect of zinc on these parameters. The observed higher magnitude of changes in the testes of lead + cadmium exposed group seems to be due to the excessive cadmium accumulation.

Animals↗
PubMed1988

Effects of sodium deoxycholate on the mechanical and electrical activities and ultrastructure of guinea pig atria.

The mechanism of cardio-inhibitory effects of sodium deoxycholate (DOC) was investigated by studying its effects on the contractility, action potentials (APs) and ultrastructure of guinea pig atrial preparations. DOC (10(-7)-10(-4) M) caused reversible negative ino- (NIE) and chrono-tropy in spontaneously beating (SBA) and NIE in electrically driven left (EDA) atria. At higher doses (greater than or equal to 1.10(-3) M) DOC caused irreversible inhibition of contractions. Atropine (10(-7)-10(-4) M) failed to inhibit both the reversible and irreversible effects of DOC. The NIE due to lower doses of DOC (less than or equal to 1.10(-4) M) was inhibited by higher [Ca2+]0, isoprenaline (10(-6)-10(-4) M), and noradrenaline (10(-6)-10(-5) M), which did not alter the dose of DOC required for the irreversible and complete NIE. In lower doses (10(-7)-10(-4) M) DOC caused a reversible inhibition of the AP durations at -20 and -40 mV (APD20 and APD40, respectively), but increased the AP duration at 90% repolarisation (APD90). At higher doses (greater than 5.10(-4) M) it caused an irreversible membrane depolarization, reduction in APD20 and APD40, and complete cessation of electrical activity. The ultrastructural changes in atria treated with 1.10(-4) M DOC were characterized by poorly delineated glycocalyx and at greater than 1.10(-3) M by disruption of sarcolemma and sarcoplasmic reticulum and swelling disruption of mitochondria. Taken together these observations show that DOC caused reversible and irreversible inhibition of atrial contractions at low (10(-7)-10(-4) M) and high (greater than 5.10(-4) M) concentrations, respectively, by different mechanisms. The former effect is due to inhibition of Ca2+ channel activity and the latter due to its detergent property causing removal of subcellular components.

Action Potentials↗
PubMed1986

Study of vaginal delivery in patients with one previous lower segment caesarean section.

This retrospective study evaluated the prospects of having a vaginal delivery following a lower segment Caesarean section in Nehru Hospital; 685 (52%) of 1,315 patients with a previous Caesarean section were given a trial of vaginal delivery with a success rate of 69%. Vaginal breech delivery was allowed in 14 patients without affecting the outcome of term babies and without maternal morbidity or mortality. There were 12 cases (1.7% incidence) of scar disruption of which 4 were of scar rupture. There was no maternal or fetal death as a result of these disruptions even though 3 mothers had subtotal hysterectomy. Pitocin was used in 144 (21%) patients. Of the 12 cases of scar disruption 5 patients had received pitocin. There was no favourable influence of prior vaginal delivery on the success of the trial, and 3 patients with scar disruption had already had a vaginal delivery in addition to a lower segment Caesarean section.

Breech Presentation↗
PubMed1985

Caffeine potentiation of propane sultone mutagenesis in barley.

Pre- and post-treatments with caffeine enhanced propane sultone (PS)-induced growth damage in barley. The caffeine post-treatments were, however, more effective in potentiating PS-induced growth damage and caused an additive effect on the frequency of chlorophyll mutations.

Caffeine↗