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Biomedical subjects

A J Richard

Publications and source records attributed to A J Richard.

12 recordsLinked to original sources
PubMed1987

Effects of diadenosine 5',5'''-P1, P4-tetraphosphate and of adenosine 5'-triphosphate on the higher order structure of calf thymus DNA.

The effective length and the hard core radius were calculated by scaled particle theory for high molecular weight calf thymus DNA in the presence of varying concentrations of diadenosine 5',5'''-P1, P4-tetraphosphate and of adenosine 5'-triphosphate in aqueous millimolar NaCl. DNA became slightly more flexible in the presence of diadenosine 5',5'''-P1, P4-tetraphosphate at concentrations of 10(-9)-10(-7) M. DNA was denatured in the presence of 5 X 10(-5) M adenosine triphosphate.

Adenine Nucleotides↗
PubMed1987

A comparison by ultracentrifugation of the effects on DNA of ethidium bromide and of acridine orange at low ionic strength.

The application of scaled particle theory to the gels formed by DNA in the ultracentrifuge has provided values for the effective length and the effective radius of the DNA particle. Ethidium bromide has been shown to cause extensive lengthening of the DNA in dilute salt. Acridine orange interaction with DNA resulted in modest changes in DNA dimensions. These results are explained in terms of binding for acridine orange and of denaturation of DNA by ethidium bromide.

Acridine Orange↗
PubMed1976

The frequency of 7S rheumatoid factors and 22S complexes in human sera with positive latex tests for rheumatoid factor.

In sera with positive latex tests for rheumatoid factors, the immunoglobulin class of the antiglobulins is influenced by the quantity of immunoglobulins present in the serum. Sera with 7S antiglobulins have high levels of IgG and IgA immunoglobulins. 22S complexes tend to be found in sera with high levels of IgM immunoglobulins. These findings suggest that the occurrence of antiglobulins and 22S complexes may be influenced by the hypergammaglobulinemia.

Adsorption↗
PubMed1975

Ultracentrifugal study of effect of sodium chloride on micelle size of fusidate sodium.

Apparent micellar molecular weights were determined with the antibiotic fusidate sodium by ultracentrifugation in varying counterion concentrations (Na+). The effects of buffer salts, pH, sodium chloride concentration, and drug concentration were studied. The results strongly support the concept of the formation of primary micelles composed of five monomer units, followed by aggregation of the pentomers into larger micelles as salt concentration increases.

Buffers↗