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Biomedical subjects

V Singh

Publications and source records attributed to V Singh.

At least 343 records · Page 19Linked to original sources
PubMed1986

Enhancement of antigonadotropin response to the beta-subunit of ovine luteinizing hormone by carrier conjugation and combination with the beta-subunit of human chorionic gonadotropin.

Previous studies have demonstrated the control of fertility in monkeys on immunization with the beta subunit of ovine luteinizing hormone (beta-oLH) along with Freund's complete adjuvant (CFA). An eventual birth control vaccine would demand immunization without CFA. Beta-oLH linked to tetanus toxoid (TT) adsorbed on alum-induced antibody response in bonnet monkeys with detoxified sodium phthalyl derivative of Salmonella enteritidis lipopolysaccharide added only in the first injection. The antibodies reacted with both LH and human chorionic gonadotropin (hCG). A higher immune response was obtained with the use of a conjugate of beta-oLH and beta-hCG linked to a common carrier (TT) or with a mixture of beta-hCG/TT and beta-oLH/TT. In both cases, the antibodies were of high affinity with Ka ranging from 5 X 10(9) to 6 X 10(10) M-1. The antibodies were devoid of reactivity with human thyroid-stimulating hormone and human follicle-stimulating hormone. Monkeys with titers above 120 ng/ml hCG binding capacity (greater than 60 ng/ml in most cases) were protected from becoming pregnant during repeated mating with males of proven fertility in ovulatory cycles.

Animals↗
PubMed1986

Comparison of passive haemagglutination test with Widal agglutination test for serological diagnosis of typhoid fever in an endemic area.

A passive haemagglutination test, using sheep red blood cells sensitised with Salmonella typhi lipopolysaccharide, was compared with the Widal test for the serological diagnosis of typhoid fever in an endemic area. The results obtained on sera from 152 patients with bacteriologically confirmed typhoid and 183 patients who did not have typhoid were analysed in terms of sensitivity, specificity, simplicity, and rapidity of the respective tests. The passive haemagglutination test was found to be more sensitive (80%) than the S typhi O antigen (71%) but marginally less sensitive than the H antigen (82%) of the Widal test. The false positive rate on control sera was 1.2% and 6.6%, respectively, for the Widal O and H antigens, and 1.6% for the passive haemagglutination test. Our findings indicate that the passive haemagglutination test is comparable with the Widal test for the serological diagnosis of typhoid fever in endemic areas, but is more simple, rapid, and economic. The passive haemagglutination test may be a useful alternative to the Widal test for the serological diagnosis of typhoid fever in busy microbiology laboratories in areas in which the disease is endemic.

Adolescent↗
PubMed1986

Structural requirement for the recognition of luteinizing hormone releasing hormone (LHRH) by monoclonal and conventional anti-LHRH antibodies.

Immunochemical studies on monoclonal and conventional anti-LHRH antibodies have been reported. The association constants (Ka) were in the order of 10(9)-10(10) L/mol when calculated from Scatchard and Steward-Petty plots. Heterogeneity indices (a) calculated from Sips plot were nearly 1.0, indicating the homogeneous nature of monoclonals. Most of the conventional anti-LHRH produced by monkey, baboon, rabbit, and dog, by immunization using LHRH linked to tetanus toxoid by the carbodiimide condensation method, showed a single slope in Scatchard analysis (except two dog antisera) and a values were nearly 1.0. Monoclonals and conventionals reacted most strongly with native LHRH(NH2). Monoclonals showed poor reactivity with LHRH free acid and LHRH fragments containing free acid. The C-terminus tetrapeptide 7-10 showed 10 times more reactivity than tripeptide 4-6. The heptapeptide 4-10 showed 100 and 1000 times more reactivity than the tetra- and tri-peptide, respectively. Introduction of the tripeptide pGlu-His-Trp-OH to heptapeptide 4-10 caused five times more inhibition in reactivity than the heptapeptide. Conventional anti-LHRH antibodies manifested specificity to the C-terminus of LHRH. These sera did not react with LHRH free acid and LHRH fragments of sequence 4-6, 7-10, and 4-10. The complete loss of reactivity of conventional antibodies and poor reactivity of monoclonal antibodies was partly regained when LHRH free acid was coupled to Lys, Lys-MDP, or (Ala)2-tuftsin, suggesting that for monoclonals and conventionals the antigenic determinant was confined to the conformation involving the C-terminus amide of LHRH.

Amides↗
PubMed1985

Management of massive air embolism during open heart surgery.

Two patients in whom a massive bolus of air was introduced into the arterial circuit and ascending aorta during valve replacement and in whom the recovery was complete are presented. The technical details of the management of this serious accident are described.

Adult↗
PubMed1985

The dominant role of amide group at C-terminus for recognition by antibody in primates against gonadotropin releasing hormone.

A monkey and a baboon immunized with GnRH-tetanus toxoid conjugate developed high anti-GnRH antibody titres which resulted in disruption of cyclicity and low estradiol and progesterone levels indicative of the inhibition of follicular development and ovulation. Sera of both animals reacted with GnRH(NH2) but were devoid of reactivity with peptide sequences, 4-6, 7-10 and 4-10 of GnRH as well as GnRH free acid. Both sera were however reactive with GnRH-Lys-muramyl dipeptide analogue and GnRH-Ala-Ala-Thr-Lys-Pro-Arg-OH. As these compounds differ from GnRH-free acid by the presence of amide linkage at C-terminus of GnRH, these studies point to the importance of the conformation involving amide group at this position for immunoreactivity.

Amino Acid Sequence↗
PubMed1985

Bioeffective monoclonal antibody against the decapeptide gonadotropin-releasing hormone: reacting determinant and action on ovulation and estrus suppression.

A monoclonal antibody generated against the decapeptide gonadotropin-releasing hormone (GnRH) was effective in intercepting the bioactivity of the hormone; it blocked ovulation in rats. The antibody reacted optimally with the native hormone. Substitution of amide at the COOH terminus by a carboxyl group decreased immunoreactivity by a factor of 200. The antibody recognized the amino acid sequences 4-6, 7-10, and 4-10 to a variable degree, which suggests that the epitope has a conformation involving the entire molecule, with the NH2- and COOH-terminal regions probably in proximity. The antibody was also competent to suppress the progression of estrus in dogs, an indication that GnRH may play an inductive role in the reproductive function of dogs.

Animals↗