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Biomedical subjects

A Brown

Publications and source records attributed to A Brown.

At least 559 records · Page 31Linked to original sources
PubMed1981

Comparative study of the sensitivity of male and female rats to methylmercury.

Male and female rats were dosed daily by gastric gavage four or five times with 8.0 mg/kg Hg as methylmercury. Treatment lowered the body weight in relation to the body weight of untreated rats to the same extent in male and female rats but when body weight was related to the initial body weight, the effect of methylmercury was more pronounced in females than in males. The important of differences in growth or loss of body weight is that in spite of the similar whole body clearance mercury concentrations were higher in females than in males. After identical doses the brains of females always contained more mercury than those of males and in both sexes the brain concentration of mercury showed a disproportionate elevation when the number of doses was increased from four to five. However, weight change alone does not explain the sex related difference in the brain concentration of mercury as this was evident even 72 h after a single dose. In agreement with the brain concentration of mercury, female rats developed more intensive co-ordination disorders and after five doses they had more extensive damage in the granular layer of the cerebellum than males.

Animals↗
PubMed1981

The occurrence and significance to animal health of Leptospira, Mycobacterium, Escherichia coli, Brucella abortus and Bacillus anthracis in sewage and sewage sludges.

Samples of sewage, sewage sludge and sewage effluent from one or more of four sewage treatment plants were examined for the presence of Leptospira, Mycobacterium, Escherichia coli, Brucella abortus and Bacillus anthracis. Brucella abortus and Bacillus anthracis were not isolated. Eleven strains of E. coli potentially enteropathogenic for calves or piglets, eight pathogenic strains of Mycobacterium and one patho;genic Leptospira strain were isolated from 101, 189 and 189 samples respectively. Sewage sludge is no;t considered to play a major part in the epidemiology of disease caused by these organisms.

Animal Diseases↗
PubMed1981

Genetic and serological analysis of the expression of crossreactive idiotypic determinants on anti-p-azobenzenarsonate antibodies and p-azobenzenarsonate-specific suppressor T cell factors.

Data are reported on the genetic control and structure of antigen-specific suppressive molecules obtained from azobenzenearsonate (ABA)-specific suppressor T cells (Ts). Ts-derived suppressor factors (TsFs) were previously shown to bear determinants encoded by genes of the I-J subregion of the H-3 major histocompatibility complex and structures encoded by VH (variable region of heavy chains) genes linked to the Igh locus. To further characterize TsF we have made use of a K light (L) chain variable region (VK) genetic marker linked to the locus governing expression of a crossreactive idiotype on anti-ABA antibodies. The experiments evaluated the possible contribution to TsF of structures under control of the VK locus. TsF was prepared in strains of mice with known Igh and VK genes. Mice carrying Igh-1e genes produced TsF that was retained by an immunoadsorbent containing bound anti-idiotype antibodies; the genetic constitution at the VK locus was not relevant. By using a panel of anti-idiotypic antibodies prepared against the antigen-binding site of antibody carrying the idiotype, against determinants outside the site or against VH structures, we determined that idiotypic structures on the TsF are associated with V-region elements associated with the H chain and not with the binding site formed by a VH-BL combination.

Animals↗
PubMed1981

Dye-containing buffered charcoal-yeast extract medium for differentiation of members of the family Legionellaceae.

The addition of 0.001% bromocresol purple and 0.001% bromothymol blue to buffered charcoal-yeast extract agar allowed differentiation between members of the family Legionellaceae. On this medium, Legionella pneumophila grew as relatively flat, pale green colonies, whereas Tatlockia micdadei (gen. nov., comb. nov., Pittsburgh pneumonia agent) produced blue-gray colonies. Fluoribacter spp. (gen. nov., atypical Legionella-like organisms) developed glistening colonies which were brighter green than those of L. pneumophila.

Bacteria↗
PubMed1981

Characterization of Fv-1 gene-product-mediated resistance transfer.

Fv-1 gene-specific resistance to ecotropic murine retroviruses can be transferred to permissive cells with RNA prepared from restrictive cells. The active RNA has a sedimentation coefficient of 20-22S at low ionic strength and multiple regions of activity (5-6S, 10-12S, 24-27S) at high ionic strength. The maximum level of resistance transfer cannot be enhanced with noninhibitory carrier RNA or facilitators of RNA uptake, and the maximum inhibition (40-60%) is independent of the MOI. The low efficiency of resistance transfer is, therefore, probably the result of a fraction of cells resistant to RNA uptake.

Animals↗
PubMed1981

Isolation of Legionella pneumophila from hospital shower heads.

Legionella pneumophila serogroup 6 was isolated from nine of 16 shower heads in a Chicago hospital ward where three patients had contracted Legionnaires' disease caused by serogroup 6 L. pneumophila. Each patient had showered there 2 to 10 days before the onset of disease symptoms. We also isolated the bacteria in two other hospitals, and found the same serogroups as had been causing Legionnaires' disease in those hospitals: serogroup 1 in Pittsburgh and serogroups 1 and 4 in Los Angeles. However, showers from hospital wards where no patients had contracted Legionnaires' disease also yielded L. pneumophila. Shower heads at the Chicago hospital were sterilized with ethylene oxide but rapidly became recontaminated, suggesting that the potable water at these hospitals may have contained the organism. The question of whether aerosols of shower water or other exposures to potable water containing L. pneumophila may cause nosocomial Legionnaires' disease has not been resolved but deserves further study.

Baths↗
PubMed1980

A question of birth.

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Delivery of Health Care↗
PubMed1980

Metabolic profiles of penaied shrimp: dietary lipids and ovarian maturation.

The major impediment to the culture of penaeid shrimp in captivity in the United States has been an inability to obtain ovarian maturation and spawning. Lipid profiles of tissues (gonads, hepatopancreas, and tail muscle) of Penaeus setiferus caught at sea have shown that cholesterol is the dominant sterol and that polyunsaturated fatty acids known to be essential in man comprise a significant portion of the fatty acid fraction. A prioprietary marine ration contains cholesterol, but is devoid of polyunsaturated fatty acids. Ovarian maturation and spawning were obtained when the shrimp diet was supplemented with an annelid rich in lipids containing these compounds. The biochemical significance of these findings is discussed.

Animal Nutritional Physiological Phenomena↗