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Biomedical subjects

M K Phillips

Publications and source records attributed to M K Phillips.

9 recordsLinked to original sources

Cutaneous histamine reactivity, histamine content of commercial allergens, and potential for false-positive skin test reactions in dogs.

The cutaneous reactivity of normal and atopic dogs to intradermal injections of histamine phosphate was evaluated. Significant differences were not found in the mean wheal diameters of either group. Commercial allergens used for intradermal skin testing and immunotherapy were determined to contain histamine. To determine whether allergen histamine content was sufficient to cause false-positive skin test results, the cutaneous response of Johnson grass allergic dogs was compared, using commercial Johnson grass allergen and commercial Johnson grass allergen with histamine removed. Significant differences were not noticed between Johnson grass and dehistaminized Johnson grass. Therefore, the histamine content of commercial Johnson grass allergen did not appear to cause false-positive skin test results for this group of Johnson grass allergic dogs.

Allergens↗

Parasitism in captive and reintroduced red wolves.

Fecal examinations revealed that at least 10 of 21 (48%) captive red wolves (Canis rufus) and eight of 12 (67%) free-ranging red wolves were infected with intestinal parasites. No captive wolves and only one of seven reintroduced wolves had dirofilariasis. Ticks were collected from 10 of 21 (48%) captive wolves and nine of 12 (75%) free-ranging animals. Ivermectin administered at a dosage of 50 micrograms/kg of estimated body weight every 30 to 60 days apparently prevented or ameliorated parasitism in red wolves.

Animals↗

Nucleotide sequence encoding the flavoprotein and iron-sulfur protein subunits of the Bacillus subtilis PY79 succinate dehydrogenase complex.

The nucleotide sequence of a 2.7-kilobase segment of DNA containing the sdhA and sdhB genes encoding the flavoprotein (Fp, sdhA) and iron-sulfur protein (Ip, sdhB) subunits of the succinate dehydrogenase of Bacillus subtilis was determined. This sequence extends the previously reported sequence encoding the cytochrome b558 subunit (sdhC) and completes the sequence of the sdh operon, sdhCAB. The predicted molecular weights for the Fp and Ip subunits, 65,186 (585 amino acids) and 28,285 (252 amino acids), agreed with the values determined independently for the labeled Fp and Ip antigens, although it appeared that the B. subtilis Fp was not functional after expression of the sdhA gene in Escherichia coli. Both subunits closely resembled the corresponding Fp and Ip subunits of the succinate dehydrogenase (SDH) and fumarate reductase of E. coli in size, composition, and amino acid sequence. The sequence homologies further indicated that the B. subtilis SDH subunits are equally related to the SDH and fumarate reductase subunits of E. coli but are less closely related than are the corresponding pairs of E. coli subunits. The regions of highest sequence conservation were identifiable as the catalytically significant flavin adenine dinucleotide-binding sites and cysteine clusters of the iron-sulfur centers.

Amino Acid Sequence↗

The antibacterial action of Tinopal AN.

The bactericidal activity of Tinopal AN [1,1-bis(3,N-5-dimethyl-benzoxazol-2-yl)-methine p-toluene sulphonate] was shown to be due to a mechanism entirely independent of its inhibitory effects upon NADH dehydrogenase which were reported previously. Whereas the compound had no significant effect upon DNA synthesis in Escherichia coli D22, RNA and protein synthesis were immediately and markedly inhibited. In confirmation, Tinopal AN caused an immediate cessation in inducible beta-galactosidase synthesis in the same organism. An in vitro assay of the transcription of calf-thymus DNA by purified E. coli RNA polymerase showed that this process was inhibited by Tinopal AN.

Bacterial Proteins↗