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Biomedical subjects

S Ramakrishnan

Publications and source records attributed to S Ramakrishnan.

At least 253 records · Page 14Linked to original sources
PubMed1979

Immunogenicity of three C-terminal synthetic peptides of the beta subunit of human chorionic gonadotropin and properties of the antibodies raised against 45-amino acid C-terminal peptide.

Immunological studies were carried out in rhesus monkeys and rabbits on three C-terminal synthetic peptides of beta-hCG (115-145; 111-145 and 101-145) after conjugating these to tetanus toxoid (TT). The immunogenicity of the peptide conjugates was comparatively poorer with reference to Pr-beta-hCG-TT conjugates at similar doses and immunization schedule. Amongst the three peptides, the best response was obtained with the 45-amino acid c-terminal peptide (45-CTP; 101-145). The anti-45-CTP recognized native hCG and was devoid of cross-reaction with hLH. hCG-induced testosterone production by mouse Leydig cells was inhibited by anti-45-CTP antiserum, although its neutralization capacity decreased more rapidly upon dilution than anti-beta-hCG sera of comparable titres. Immune complexes formed by the anti-45-CTP with hCG had a lower sedimentation value than those formed by anti-beta-hCG antisera with hCG, suggesting the presence of a limited number of immuno-determinant regions in the 45-amino acid C-terminal synthetic peptide.

Amino Acids↗
PubMed1978

Recognition of the beta-subunit of human chorionic gonadotropin and sub-determinants by target tissue receptors.

The beta-subunit of human chorionic gonadotropin, purified immunochemically to eliminate undissociated human chorionic gonadotropin, induced testosterone production by mouse Leydig cells at concentrations 400-fold higher than human chorionic gonadotropin. Steroidogenesis was also stimulated by a synthetic fragment of the beta-subunit of human chorionic gonadotropin conforming to the peptide sequence residues 39--71, whereas peptide sequence residues 39--56 and three C-terminal fragments (residues 115--145, 111--145 and 101--145) failed to cause steroidogenesis. These studies suggest the presence in the beta-subunit of human chorionic gonadotropin of determinants recognized by the tissue receptors, a part of these determinants residing between amino acid residues 57--71.

Animals↗
PubMed1978

Michaelis-Menten constant of serum aspartate amino transferase (AST) in heart and liver diseases.

The activity and the Km (Michaelis-Menten constant) of serum aspartate amino transferase (AST) were investigated in normal subjects, in patients with recent myocardial infarction, and in patients with infectious hepatitis. AST activity was elevated in both groups of patients. While the Km value of serum AST was not affected in myocardial infarction, it was increased in infectious hepatitis when the total serum bilirubin was higher than 13 mg/dl. Thus, while an investigation of activity of AST in serum did not help in differential diagnosis of heart and liver diseases, determination of Km value was helpful in the diagnosis of infectious hepatitis.

Alkaline Phosphatase↗