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Biomedical subjects

R S Anderson

Publications and source records attributed to R S Anderson.

121 records · Page 7Linked to original sources
PubMed1970

Nucleic acid homologies among oxidase-negative Moraxella species.

The deoxyribonucleic acid (DNA) base composition and DNA homologies of more than 40 strains of oxidase-negative Moraxella species were determined. These bacteria have also been identified as belonging to the Mima-Herellea-Acinetobacter group and the Bacterium anitratum group, as well as to several other genera including Achromobacter and Alcaligenes. The DNA base content of these strains ranged from 40 to 46% guanine plus cytosine. DNA-DNA competition experiments distinguished five groups whose members were determined by showing 50% or more homology to one of the reference strains: B. anitratum type B5W, Achromobacter haemolyticus var. haemolyticus, Alcaligenes haemolysans, Achromobacter metalcaligenes, and Moraxella lwoffi. A sixth group comprised those strains showing less than 50% homology to any of the reference strains. Negligible homology was found between strains of oxidase-negative and oxidase-positive Moraxella species in DNA-DNA competition experiments. However, evidence of a distant relationship between the two groups was obtained in competition experiments by using ribosomal ribonucleic acid.

Bacteria↗
PubMedDate not supplied

Hemocyte-derived reactive oxygen intermediate production in four bivalve mollusks.

Luminol-dependent chemiluminescence (LDCL) and nitroblue tetrazolium (NBT) reduction assays have been used to measure reactive oxygen intermediate (ROI) production by oyster (Crassostrea virginica) hemocytes, as well as ROI modulation caused by disease or exposure to environmental toxicants. However, ROI responses measured by these tests apparently vary considerably among other bivalve species. In all species tested, unstimulated hemocytes produced small quantities of ROIs. In C. virginica and Geukensia demissa phagocytosis or treatment with phorbol myristate acetate triggered significantly augmented, but kinetically dissimilar, ROI responses; however, no induction was recorded in two clam species (Mya arenaria and Mercenaria mercenaria). This was supported by both LDCL and NBT assays, measuring activity of the myeloperoxidase/hydrogen peroxide system and production of intracellular superoxide anion, respectively. The failure of the clams to respond to standard ROI-eliciting procedures is possibly indicative of interspecies differences in hemocyte-mediated antimicrobial defense mechanisms.

Animals↗
PubMedDate not supplied

DIfferential ability of Ambystoma tigrinum hepatic microsomes to produce mutagenic metabolites from polycyclic aromatic hydrocarbons and aromatic amines.

A number of carcinogenic aromatic amines when activated by liver microsomes from a salamander, Ambystoma tigrinum, are mutagenic for Salmonella tester strains sensitive to frameshift mutagens. However, 2 polycyclic aromatic hydrocarbons (PAH) (benzo[alpha]pyrene (BaP) and perylene) that are rendered mutagenic by mammalian microsomes are not activated by Ambystoma mixed-function oxidases. BaP was chosen for study because it is a well-known environmental carcinogen; perylene, an isomer of BaP, has been implicated as a etiological agent in cutaneous neoplasia in Ambystoma. These results support the observation that amphibians are quite resistant to PAH carcinogenesis and suggest that aromatic amines may be more appropriate model carcinogens.

Animals↗
PubMedDate not supplied

Modulation of Crassostrea virginica hemocyte reactive oxygen species production by Listonella anguillarum.

Luminol- and lucigenin-augmented chemiluminescence (CL) were used to evaluate the ability of Listonella (formerly Vibrio) anguillarum to stimulate the production of reactive oxygen species (ROS) by Crassostrea virginica hemocytes. Whereas heat-killed L. anguillarum stimulated hemocyte CL in the lucigenin system, viable L. anguillarum did not. Neither viable nor heat-killed bacteria stimulated hemocyte production of luminol CL. Metabolically active L. anguillarum generated ROS, as indicated by luminol and lucigenin CL. It is proposed that bacterial catalase suppressed hemocyte-derived luminol CL. L. anguillarum, which possesses the antioxidant enzyme catalase, suppressed luminol CL generated by zymosan-stimulated hemocytes. Conversely, the catalase negative bacterium Carnobacterium piscicola had no effect on hemocyte-derived luminol CL elicited by zymosan. The inability of viable L. anguillarum to stimulate hemocyte ROS production, as measured by CL, does not support the proposed role for ROS in hemocyte-mediated bactericidal activity.

Animals↗
PubMedDate not supplied

A comparison of the chemiluminescent response of Crassostrea virginica and Morone saxatilis phagocytes to zymosan and viable Listonella anguillarum.

If reactive oxygen species (ROS) produced by hemocytes of the eastern oyster, Crassostrea virginica, impart bactericidal activity, exposure of hemocytes to bacteria should result in increased ROS generation. In an earlier study, this hypothesis was tested using luminol- and lucigenin-augmented chemiluminescence (CL) to measure ROS production. The bacterium Listonella anguillarum did not stimulate a net increase in hemocyte-derived CL, and it was suggested that bacterial antioxidants might suppress hemocyte CL. In the present study a comparison was made, under identical assay conditions, of the zymosan- and bacteria-enhanced luminol CL produced by eastern oyster hemocytes and by striped bass (Morone saxatilis) macrophages, for which L. anguillarum has been shown to be a stimulus in CL reactions. The response to zymosan produced by bass phagocytes was two orders of magnitude greater than that generated by eastern oyster hemocytes. Whereas an increase in net ROS production was not evident when oyster hemocytes were exposed to L. anguillarum, significant stimulation of striped bass macrophage-derived CL occurred. These data suggest that striped bass macrophages have a greater capacity to generate ROS than oyster hemocytes, enabling them to surpass the antioxidant capability of L. anguillarum and produce a luminol CL response.

Animals↗
PubMedDate not supplied

Cataract--webbed Peromyscus. I. Genetics of cataract in P. maniculatus.

Cataract--webbed (cw) in the deer mouse (Peromyscus maniculatus) is a recessive mutant that is manifested by syndactyly (involving soft tissues) and eye defects including cataract. Within cw/cw mice, the age at which cataract first appears is genetically controlled. Evidence for the activity of genetic modifiers is the early appearance of cataracts in the offspring of parents that developed cataracts at early ages.

Animals↗
PubMedDate not supplied

Uptake and distribution of radioactive selenium in cataractous rat lens.

A cataractous dose of sodium selenite tagged with 75Se was injected into 10 day old rat pups. It was shown for the first time that 75Se accumulated in the soluble and insoluble proteins of the lens. 75Se was not concentrated in the nuclear cataract. Interaction of selenium with structural or enzymatic proteins of the lens may be an important step in the mechanism of selenite induced cataract.

Animals↗