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Biomedical subjects

L W Clem

Publications and source records attributed to L W Clem.

At least 109 records · Page 6Linked to original sources
PubMed1977

Phylogeny of immunoglobulin structure and function; characterization of the cysteine-containing peptide involved in the pentamerization of shark IgM.

Nurse shark (Ginglymostoma cirratum) immunoglobulins were studied in an attempt to further define the relationship between the naturally occurring monomeric 7S and the pentameric 19S forms of extracellular IgM. A peptide containing the cysteine involved in the formation of intersubunit disulfide bonds linking 7S monomers into pentamers was isolated from the H chain of the 19S molecule and characterized. A similar peptide was also isolated from the H chain of the naturally occurring 7S molecule. These observations serve to substantiate previous claims that the two shark proteins belong to the same immunoglobulin class.

Amino Acid Sequence↗
PubMed1977

Phylogeny of lymphocyte heterogeneity. I. Membrane immunoglobulins of teleost lymphocytes.

Immunofluorescence studies of bream lymphoid tissues revealed that our 90% of the lymphocytes from blood, anterior kidney, spleen and thymus exhibited membrane immunoglobulin determinants. Furthermore, a majority of such cells were observed to undergo patching and capping when the membrane proteins were complexed with antisera to fish serum immunoglobulins. Lactoperoxidase catalysed radioiodination, detergent lysis and immunoprecipitation with appropriate antisera were employed to study the properties of this membrane immunoglobulin. Quantification, by inhibition of immunoprecipitation with serum immunoglobulin, indicated the average amount of immunoglobulin determinants for bream lymphocytes from either blood, anterior kidney, spleen or thymus to be about half that present on mouse B cells. Physiochemical characterization of labeled membrane immunoglobulin from bream lymphocytes suggested that only one class of immunoglobulin heavy chain was present and that about one-half of this material resembled the monomeric (2H-2L chain) IgM-like proteins present in bream serum. A major unanswered question raised by this study was whether or not certain of the bream membrane immunoglobulin determinants were associated with molecules that did not resemble "classical" immunoglobulins.

Animals↗
PubMed1976

Esterification of J chain and its effect on electrophoretic mobility in sodium dodecyl sulfate polyacrylamide gels.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis yields mobilities indicative of molecular weights of approximately 27 000 for human J chain and approximately 14 000 for nurse shark J chain, in contrast to values of approximately 15 500 and approximately 12 200, respectively, obtained by other methods. The relatively high content of acidic amino acids of human J chain as compared to nurse shark J chain suggested that the greater error in the sodium dodecyl sulfate determined molecular weight for human J chain may be due to a charge anomaly. The overall net negative charge on human J chain was decreased by forming methyl esters of the carboxyl groups, resulting in a sodium dodecyl sulfate determined molecular weight of approximately 17 700. Methylated nurse shark J chain did not show a significant difference in sodium dodecyl sulfate electrophoretic mobility from the non-methylated form. These results form the basis for a possible explanation of an occasional artifact in a widely used analytical method.

Animals↗
PubMed1976

Inhibition of macrophage migration by normal guinea pig intestinal secretions.

The incubation fluid from 24-hr cultures of normal guinea pig small intestines was found to contain activity capable of inhibiting the migration of normal guinea pig peritoneal macrophages. Each of three different culture fluids showed macrophage inhibitory activity in the 25,000-55,000 mol wt range when subjected to Sephadex G-100 gel filtration. One of these three preparations also contained inhibitory activity in the excluded volume. The low molecular weight activity was nondialyzable and heat stable to 56 degrees for 30 min. It was destroyed by boiling for 1 hr, and its activity was reversed by 10(-4)M epinephrine. Based upon these properties it is suggested that this activity was due to migration inhibitory factor (MIF). The high molecular weight inhibitor was stable to heating and its activity was not reversed by epinephrine. This material was most likely endotoxin. The presence of MIF, which may be associated with T-cell activity in the intestine, suggests that cell-mediated immunity (CMI) could play a role in local protection against gut infections. Furthermore, its presence in normal intestinal secretions suggests that some MIF-producing cells are always being stimulated by normal flora. The question is thus raised whether further specific stimulation of local CMI in the gut could be successful.

Animals↗
PubMed1975

Phylogeny of immunoglobulin structure and function. VII. Monomeric and tetrameric immunoglobulins of the margate, a marine teleost fish.

The margate, a marine teleost fish, was found to contain both high (16S) and low (7S) molecular weight antibodies 17 days after initial immunization. The 16S antibodies were detectable with both haemagglutination and antigen-binding assays, whereas the 7S antibodies were only detected by the latter technique. Margate 16S (molecular weight approximately 700,000) and 7S (molecular weight approximately 175,000) immunoglobulins were isolated and shown to be antigenically indistinguishable. They therefore appear to belong to the same immunoglobulin class and to have a tetramer--monomer relationship. Experiments with stored sera indicated the 7S protein is probably not an in vitro degradation product of the 16S molecule.

Animals↗
PubMed1975

The hapten-carrier effect in teleost fish.

The sea robin (Prionotus evolans), a representative teleost fish, was found to undergo the hapten-carrier effect, suggestive of T-B cell cooperativity, in vivo with dinitrophenyl as the hapten and bovine gamma-globulin or bovine serum albumin as carriers. In contrast to mammalian systems, the secondary anti-hapten response in the sea robin was found to involve exclusively high molecular weight antibody.

Absorption↗
PubMed1975

Antibody response in the intestinal secretions of volunteers immunized with various cholera vaccines.

The efficacy of various cholera vaccines in eliciting an intestinal antibody response was assessed in human volunteers who received oral live, oral killed, or parenteral cholera vaccines, or placebo. The intestinal immune response in terms of antibacterial and antitoxin antibodies was determined 2 and 4 weeks after immunization. By means of the mouse peritoneum opsonization assay and the infant mouse protection test, antibacterial activity could be detected in the intestinal secretions of volunteers who had been immunized either orally or by the parenteral route. Significant protective activity and duration of immunity were observed with the oral killed vaccine. The bacteriological data indicated the absence of significant intestinal colonization of the live attenuated strain after oral administration, and probably explains the observed lack of effectiveness of the oral vaccine compared with that of the killed vaccine. The predominant immunoglobulin class of intestinal antibody was found to be IgA. None of the vaccines used in the study elicited significant antitoxin activity in the intestinal secretions, as determined by the skin permeability neutralization test.

Adult↗