Search PubMed⌕ Search

Biomedical subjects

R S Farr

Publications and source records attributed to R S Farr.

At least 55 records · Page 3Linked to original sources
PubMed1972

Shared antigens between heterologous bacterial species.

Sera from normal rabbits were shown to have antibodies that bound radiolabeled test antigens derived from many taxonomically unrelated bacteria. Sera from rabbits that had been immunized with sonically treated material of 12 different bacteria, including M. bovis strain BCG, had antibodies that bound not only radiolabeled homologous test antigens but also radiolabeled antigens from many unrelated bacteria. Binding by normal and immunized sera to radiolabeled test antigens was inhibited by homologous unlabeled test antigens but not by substances such as bovine serum albumin, polyvinylpyrrolidone, sheep erythrocytes, and endotoxin. The broad range of shared or cross-reactivity among antigens in bacteria may explain the presence of antibodies to many bacteria in sera from normal humans and previously unimmunized experimental animals. The presence of these antibodies raises the question whether resistance to many bacterial infections may be partly due to immune mechanisms, whether cellular or humoral, that have been stimulated by unrelated bacteria.

Animals↗
PubMed1971

Antigenic Differences Between Mycobacterium bovis Strain BCG and an Isoniazid-Resistant Mutant.

The antigenicities of Mycobacterium bovis strain BCG and an isoniazid (INH) - resistant mutant were compared. Sonic extracts of heat-killed, washed bacteria were injected into rabbits, and antisera were produced (anti-BCG and anti-BCG-R). The sonic extracts were also subjected to ultracentrifugation, and test antigens were prepared from the resulting supernatants (BCG and BCG-R). The antigens were labeled with (131)I, and the antisera were tested for their capacity to bind (131)I-BCG and (131)I-BCG-R by precipitating (131)I-antigen-antibody complexes with anti-rabbit gamma globulin. Significant differences were detected between the two test antigens. Immunodiffusion studies with unabsorbed antisera and antisera absorbed with BCG and BCG-R suggested that an antigenic component in BCG is lacking or diminished in BCG-R and that anti-BCG has antibodies not found in anti-BCG-R. These quantitative and qualitative differences were confirmed by inhibition studies. Complete inhibition was achieved in all systems by both test antigens when either was added in sufficient concentration. As expected, BCG-R inhibited the binding of (131)I-BCG-R by anti-BCG-R or anti-BCG (or both) to a greater extent than BCG, and BCG was a better inhibitor in an (131)I-BCG-anti-BCG-R system. However, in an (131)I-BCG-anti-BCG test system, BCG was the better inhibitor only at high concentrations. It was concluded that the test antigens possess different proportions of identical or cross-reacting components and that INH-sensitive organisms possess a component(s) that is diminished or absent in the INH-resistant mutant. Whether this component(s) is responsible for INH-resistance is not known.

Journal Article↗
PubMed1969

Binding between components of the tubercle bacillus and humoral antibodies.

Studies were undertaken to find a substance or substances for use in primary binding types of tests to detect humoral antibodies in rabbits and monkeys exposed to the tubercle bacillus that would distinguish between strains of mycobacteria. The antigen employed was a component of the 5159 strain of Mycobacterium tuberculosis that was obtained following sonification, ultracentrifugation, electrophoresis, and elution from a preparative polyacrylamide column. When the antigen was labeled with (131)I, specific binding was observed in sera from immunized rabbits and BCG-protected rhesus monkeys by the radio-gel electrophoresis and ammonium sulfate tests. This component was partially characterized, and its major antigenic determinants were associated with anionic mucopolysaccharides. Electrophoretically at pH 8.3 it migrated anodally to albumin, its molecular weight was between 9,000 and 12,000, and it was soluble in 50% saturated ammonium sulfate. Binding to antibody was destroyed after treatment with Pronase, but not after DNase or RNase. Inhibition of the reaction, as measured by the ammonium sulfate test, between the (131)I-labeled component and antisera from rabbits that had been immunized with sonicated 5159 organisms, was studied. These experiments demonstrated a capacity to define subtle similarities and differences among different mycobacteria and mycobacterial components. Some microorganisms not clearly related to mycobacteria also partially inhibited this reaction, suggesting that they shared antigenic groups with the component derived from 5159 organisms. The studies described suggested the advisability of using direct primary tests and purified components of mycobacteria to differentiate further the antigenic groups between individual pathogenic mycobacteria and between pathogenic and nonpathogenic organisms.

Animals↗
PubMed1969

Structural changes in human serum albumin induced by ingestion of acetylsalicylic acid.

Acetylsalicylic acid (aspirin) acetylates human serum albumin under physiologic conditions in vitro. These investigations were done to determine whether this phenomenon occurs in vivo and to delineate the site(s) of acetylation on the albumin molecule. Albumin was reacted in vitro with aspirin labeled with (14)carbon at the acetyl-1 or the carboxyl carbon. The altered albumin was hydrolyzed with trypsin and peptide mapping performed. Albumin so treated contains a unique peptide, designated "A," and shows diminution of two normal peptides, designated "B" and "C." Peptide "A" is never seen in normal albumin. Amino acid analyses indicate that peptide "A" equals the sum of peptides "B" and "C." Furthermore all three peptides contain lysine but lack arginine. Thus peptide "A" is formed by the acetylation of a lysine residue which is normally susceptible to trypsin and yields peptides "B" and "C." Radioautography of the peptide maps show most of the acetyl-1-(14)C activity in peptide "A." This indicates that one of the lysine residues in this peptide is the preferential site for the transacetylation reaction. Peptide "A," used as a marker for acetylation, is found in albumin from patients who take aspirin but is not demonstrable in albumin from one of these patients while she was taking sodium salicylate. A transacetylation reaction between aspirin and human albumin occurs in vivo and is similar to that observed in vitro.

Amino Acids↗