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Biomedical subjects

M K Das

Publications and source records attributed to M K Das.

At least 109 records · Page 6Linked to original sources
PubMed1983

Interaction of Fab mu of anti-galactocerebroside antibody with galactocerebroside liposomes.

The binding of Fab mu of rabbit anti-galactocerebroside antibody to antigen incorporated in unilamellar liposomes has been investigated by fluorescence and circular dichroism measurements. The fluorescence intensity of Fab mu is found to be quenched considerably in the presence of liposomes concomitant with a blue-shift of the emission maximum. It is inferred from circular dichroism studies that there are changes in the aromatic residues and the disulfides as well as in the folding of peptide backbone of Fab mu. The results suggest that antigen-associated liposomal membrane induces changes in both the tertiary and the secondary structure of Fab mu.

Animals↗
PubMed1983

Low haemoglobin levels in A1 and O blood groups.

In an anthropological investigation of 114 Bengalee families of the Sodepur industrial suburb of Calcutta, the average haemoglobin level is found to be significantly lower in males with A1 blood group than those with other blood groups, and this is more marked in young age. A depression of the haemoglobin level is also apparent in women of reproductive age who have blood group O, conforming to the suggestion of greater bleeding tendencies in individuals with O blood group than in others.

ABO Blood-Group System↗
PubMed1982

Liposomes as carrier for production of sugar specific antibodies: preparation of antigalactosyl antiserum.

Negatively charged multilamellar liposomes, covalently coupled with p-aminophenylated derivative of D-galactose, have been used to raise galactose specific antibodies in rabbits. The specificity of the antiserum has been characterized by immunodiffusion, quantitative precipitation and hapten inhibition studies. In addition to its specificity against the sugar moiety the antibody population also recognizes the aromatic aglycone portion of the introduced hapten. This offers a new method of raising sugar specific antibodies using liposomes as immunological carriers.

Animals↗
PubMed1982

The adjuvant effect of liposomes in eliciting anti-galactosyl antibodies.

Negatively-charged, multilamellar liposomes, covalently coupled with p-aminophenyl-beta-D-galactopyranoside, elicited the rabbits a nearly equivalent anti-galactosyl immune response in both the presence and the absence of complete Freund's-adjuvant (CFA). The antibody response obtained using liposomes both as the carrier and adjuvant was found to be better than that obtained through the conventional way of using protein carrier in CFA. The results suggest an effective role of liposomes as adjuvant in the production of sugar-specific antibodies.

Adjuvants, Immunologic↗
PubMed1981

Fluorimetric studies of the binding of Momordica charantia (bitter gourd) lectin with ligands.

The association constants for the binding of a series of ligands with a galactose-specific lectin from Momordica charantia (bitter gourd) has been determined through the ligand-induced quenching of protein fluorescence. Analysis of the iodide quenching suggested that there is a slight increase in the accessibility of tryptophan residues of the lectin on binding lactose.

Carbohydrates↗
PubMed1981

Antihyperlipidemic activity of amine cyanoboranes, amine carboxyboranes, and related compounds.

A series of amine cyanoboranes and amine carboxyboranes were observed to be antihyperlipidemic agents in mice; i.e., they lowered serum cholesterol and triglyceride levels significantly. These compounds appeared to inhibit lipid synthesis in the early stages. The ability to lower serum cholesterol levels appeared to correlate with the suppression of the regulatory enzyme of cholesterol synthesis, beta-hydroxy-beta-methylglutaryl-CoA reductase activity. The reduction of serum triglycerides correlated with ability of the borane compound to suppress liver fatty acid synthetase activity.

Acetate-CoA Ligase↗
PubMed1980

Anti-inflammatory activity of amine cyanoboranes, amine carboxyboranes, and related compounds.

Amine cyanoboranes and amine carboxyboranes (boron analogs of alpha-amino acids) were shown to inhibit inflammation. The analogs effectively blocked general inflammation, induced arthritis, and the writhing reflex associated with inflammation pain, while the inflammation associated with pleurisy was marginally inhibited. The boron analogs were shown in vitro to inhibit the release of lysosomal enzymes from liver and polymorphonuclear neutrophils. Furthermore, prostaglandin synthesis was blocked by these agents at a low concentration, i.e., 10(-6) M. Liver oxidative phosphorylation processes also were uncoupled by these agents, but the migration of polymorphonuclear neutrophils was unaltered at 10(-4) M. The elevation of cyclic adenosine monophosphate levels in polymorphonuclear neutrophils correlated positively with in vivo antiarthritic activity. Initial studies in rodents demonstrated that these boron analogs can be used at safe therapeutic doses.

Analgesics↗
PubMed1979

Boron betaine analogs: antitumor activity and effects on Ehrlich ascites tumor cell metabolism.

Several newly synthesized boron betaine analogs had antitumor activity in Ehrlich ascites, Walker 256 ascites carcinosarcoma, and Lewis lung screens and marginal activity in the B-16 melanotic melanoma screen. In vivo testing demonstrated that trimethylamine-cyanoborane inhibied Ehrlich ascites cell DNA and protein syntheses as well as gene modulation by chromatin protein phosphorylation and methylation. Trimethylamine-cyanoborane increased cyclic-AMP levels. In vitro testing showed that nuclear DNA polymerase, thymidylate synthetase, S-adenosylmethyltransferase, nonhistone chromatin methylation, deoxyribonuclease, ribonuclease, and cathepsin were inhibited by the boron analogs. These compounds did not demonstrate high antitumor activity at the doses employed, but blockage of methyl transfer from S-adenosylmethionine was established as a feasible method for controlling cell proliferation.

Animals↗
PubMed1979

The binding of aromatic derivatives of beta-D-galactopyranosides to the FAB' of immunoglobulin J539. Observations on the nature of ligand-antibody interactions.

A number of D-galactopyranosides bearing aromatic substituents have been prepared, and their binding to immunoglobulin J539 (Fab') has been studied. It appears that the main contribution of the 6-O-aromatic moiety to binding arises from the fact that it imparts an increased hydrophobicity to the ligand, causing a decrease in its hydration (solubility) that results in a greater free-energy of binding. In the D-galactosides having an aromatic aglycon, the phenyl group appears to partake in actual interactions with the protein.

Galactosides↗
PubMed1978

Influence of phosphate ligands in abolishing the conformational difference between ribonuclease A and its acid-denatured derivative.

The initial structural alteration of RNAase A due to acid denaturation (0.5 N HCl, 30 degrees C) that accompanies deamidation (without altering enzymic activity) has been dectected by spectrophotometric titration, fluorescence and ORD/CD measurements. It is shown that acid treated RNAase A has an altered conformation at neutral pH, 25 degrees C. This is characterized by the increased accessibility of buried tyrosine residue(s) towards the solvent. The most altered conformation of RNAase A is found in the 10 h acid-treated derivative. This has about 1.5 additional exposed tyrosine residues and a lesser amount of secondary structure than RNAase A. All three methods (titration, fluorescence and CD) established that the structural transition of RNAase A is biphasic. The first phase occurs within 1 h and the resulting subtle conformational change is constant up to 7 h. Following this, after the release of 0.55 mol of ammonia, the major conformational change begins. The altered conformation of the acid-denatured RNAase A could be reversed completely to the native state through a conformational change induced by substrate analogs like 2'- or 3'-CMP. Thus the monodeamidated derivative isolated from the acid-denatured RNAase A by phosphate is very similar to RNAase A in over-all conformation. The results suggest the possibility of flexibility in the RNAase A molecule that does not affect its catalytic activity, as probed through the tyrosine residues.

Amides↗