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Biomedical subjects

R Ramasamy

Publications and source records attributed to R Ramasamy.

137 records · Page 8Linked to original sources
PubMed1976

Role of membrane structures in B-lymphocyte activation. The effect of binding anti-immunoglobulin, aggregated IgG and immune complexes.

It is shown that the binding of bivalent anti-immunoglobulin preparations to the surface immunoglobulin of murine B lymphocytes as well as the binding of aggregates of IgG or immune complexes does not lead to detectable increase in cell division in microcultures. Treating lymphocytes with immune complexes and aggregated IgG does not abolish the subsequent mitogenic response induced by LPS. The background mitosis observed in culture is inhibited with anti-immunoglobulin antibodies.

Animals↗
PubMed1976

The specificity of the Fc receptor on murine lymphocytes for immunoglobulins of the IgG and IgM classes.

It is shown that the Fc receptor for IgG on lymph node cells recognizes IgG molecules of mouse IgG1, IgG2a and IgG2b subclasses. The presence of an intact CH3 domain is required to bind IgG to the Fc receptors. While monomeric IgG molecules are shown to bind to Fc receptors, heat aggregated IgG was found to bind more efficiently. The various forms of IgM molecules investigated show only weak or no binding in comparison. The significance of these results is discussed with relevance to the possible biological function of the Fc receptors on lymphocytes.

Animals↗
PubMed1975

C3 receptors on direct plaque-forming cells.

Using a rosette technique it is shown that only a small proportion of direct plaque-forming cells posses detectable C3 receptors 5 and 7 days after antigenic stimulation. The significance of this result is discussed.

Animals↗
PubMedDate not supplied

Lanthanide complexes of aminophosphonates as shift reagents for 7Li and 23Na NMR studies in biological systems.

A systematic NMR characterization of various Dy(III) complexes of linear and macrocyclic aminophosphonates as 7Li and 23Na NMR shift reagents for biological systems was undertaken. Their efficacy as shift reagents (SR) was tested under constant aqueous solution ionic strength conditions at pH 7.5 as a function of rho = [SR]/[M+]. Further characterization of the two best SRs, Dy(PcPcP)2(7-) and Dy(DOTP)5-, led to the conclusion that, although quite sensitive to solution pH and the presence of alkali metal ions and Mg2+ and Ca2+, these complexes were stable towards hydrolysis by phosphatases. The lack of precipitation of its solutions in the presence of Ca2+, allowed the choice of Dy(DOTP)5- as the best overall SR for biological studies. Other SRs, like Dy(TTHA)3-, although less sensitive to pH and to divalent ions, require significantly higher concentrations to yield the same shifts, leading to large bulk susceptibility artifacts in perfused tissues and organs.

Alkaline Phosphatase↗
PubMedDate not supplied

Hepatic abscess complicating paratyphoid infection.

Salmonellosis is ubiquitous and is a world-wide public health concern. Liver abscesses are occasionally reported in Salmonella typhi infections, they are a very rare complication of Salmonella paratyphi infections. A 28 year old male patient without any prior medical history presented with fever, abdominal pain and a tender hepatomegaly. The imaging studies revealed multiple liver abscesses and an ultrasound (US) guided aspiration of the abscess yielded heavy growth of Salmonella paratyphi A. He was treated successfully by percutaneous drainage of the abscesses and appropriate antibiotics.

Adult↗
PubMedDate not supplied

Synthetic peptides in malaria research.

Peptides synthesized by solid-phase procedures find a number of applications in research aimed at developing new methods of controlling malaria. The use of peptides has allowed the delineation of B and T cell epitopes in parasite antigens, convenient measurement of antibody levels, analysis of cellular immune responses, cell invasion studies and development of synthetic vaccines. Current trends in the use of synthetic peptides in malaria research are outlined in this review.

Amino Acid Sequence↗