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Biomedical subjects

A M Craig

Publications and source records attributed to A M Craig.

96 records · Page 6Linked to original sources
PubMed1970

Binding of polycyclic aromatic hydrocarbons to polyadenylic acid.

A number of polycyclic aromatic hydrocarbons bind to the double-stranded, acid form of polyadenylic acid (poly A). Model building shows that these hydrocarbons may intercalate in the helix, and be well protected from contact with the aqueous medium. Hydrocarbons that are too large to be so protected are found not to bind. A size criterion for the binding of hydrocarbons to poly A therefore exists. This criterion differs from one that was previously found for DNA. The size criteria for DNA and poly A, together, serve as strong evidence for the intercalation model for hydrocarbon complexes.Model-building experiments show that only a small portion of the hydrocarbon need extend into the medium to prevent binding. This finding implies that in two cases (1,2,5,6-dibenzanthracene.poly A and 3,4-benzpyrene.DNA) the structure of the complex is almost completely determined by the size criterion alone.

Adenine Nucleotides↗
PubMedDate not supplied

Immunotoxicity of technical pentachlorophenol (PCP-T): depressed humoral immune responses to T-dependent and T-independent antigen stimulation in PCP-T exposed mice.

The effects of chronic dietary exposure to technical pentachlorophenol (PCP-T) on humoral immune responses in mice were examined. Primary and secondary splenic antibody responses to the T-dependent antigen, sheep red blood cells (SRBC), were examined in Swiss-Webster mice using our recently developed screening technique, the Hemolytic Antibody Isotope Release (HAIR) assay. To assess direct effects of PCP-T on B cells, the splenic plaque-forming cell response and serum antibody titers to the T-independent antigen, dinitrophenyl (DNP)-Ficoll, were examined. PCP-T exposure altered both the kinetics and the magnitude of the humoral antibody responses to SRBC and DNP-Ficoll. Peak splenic antibody production and serum antibody titers were delayed and the magnitude of the antibody responses were dose-dependently suppressed by PCP-T exposure. IgM responses appeared to be more sensitive to PCP-T-induced suppression than the IgG response. Significant depression of the IgM anti-SRBC splenic HAIR response was apparent as early as 2 weeks after initiation of PCP-T exposure and persisted for at least 8 weeks after termination of PCP-T feeding. Liver weight and serum lactate dehydrogenase (LD-L) and alanine aminotransferase (ALT) levels were significantly elevated during PCP-T exposure and returned to control levels after a 4-6 week recovery period. The immunotoxic effect of PCP on humoral immunity was observed only in animals exposed to technical grade PCP known to be contaminated with significant levels of other chlorinated phenols as well as non-phenolic impurities including chlorinated dioxins, furans, and diphenyl ethers. Animals exposed to analytical grade PCP did not exhibit depressed humoral immunity.

Animals↗