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Biomedical subjects

J Mitchell

Publications and source records attributed to J Mitchell.

At least 433 records · Page 24Linked to original sources
PubMed1976

A direct estimate of the number of human gamma-globin genes.

The number of genes specifying human gamma-globin has been determined directly by hybridization of complementary DNA to total human DNA. The complementary DNA was enriched in sequences specific for gamma-globin genes by transcribing globin mRNA isolated from fetal reticulocytes with viral reverse transcriptase, and collecting the material which does not back-hybridize to adult globin mRNA. When hybridized in cDNA excess to DNA, very similar values are found for gamma-gene number as for beta-gene number, suggesting two or at most three gamma-globin genes per haploid human genome. This indicates that the non-Mendelian ratios of gamma-chain mutants found in heterozygotes are due to transcriptional or post-transcriptional regulation rather than to gene dosage. The number of each major human globin gene has now been determined directly by molecular methods.

Genes↗
PubMed1976

A copulatory system in the hypothalamus and tegmentum of the domestic chick.

A tract in the chick is described that runs from the posterior nucleus paraventricularis magnocellularis (PVM) through the lateral hypothalamus to a small area of the anterior tegmentum, which is adjacent to the ventral tegmental area. Bilateral lesions of the posterior PVM or of the PVM tract or of its tegmental destination abolish the facilitation of copulation in male chicks by testosterone. The effect is specific in that the facilitation of attack is either unaffected or only slightly depressed by such lesions, while being itself specifically depressed by other hypothalamic lesions. No other hypothalamic tracts were found that were necessary for the facilitation of copulation. An equivalent copulatory system probably exists in the mammal, with a more diffuse distribution in the preoptic area but with similar connections back to the tegmentum.

Aggression↗
PubMed1976

Measurement of dengue virus-specific double-stranded ribonucleic acid in infected primate cell extracts by microquantitative complement-fixation methods.

Microquantitative complement-fixation methods have been applied to the detection and quantitation of double-stranded RNA (dsRNA) in cytoplasmic extracts of uninfected and dengue virus-infected primate cell lines. LLC-MK2 and PGLC-33H cells exhibited increased levels of dsRNA following dengue virus infection. Cytoplasmic extracts of infected and uninfected LLC-MK2 cells subjected to density gradient analysis showed that increased levels of dsRNA were associated with structures believed to be virus-specific. Primate cell dsRNA and dengue dsRNA preferentially reacted with rabbit anti-rIn-rCn, while reovirus dsRNA and rAn-containing synthetic duplexes preferentially reacted with anti-rAn-rUn.

Animals↗
PubMed1974

Enzyme changes in human small bowel mucosa during culture in vitro.

Human jejunal biopsy slices were maintained in culture for up to 48 hours. At 24 hours there was good morphological preservation but by 48 hours there was ultrastructural evidence of damage to the enterocytes. During culture the tissue had lost a certain amount of protein. At the same time the levels of three brush border enzymes (alkaline phosphatase, alpha-glucosidase, and leucyl-beta-naphthylamidase) and one lysosomal enzyme (N-acetyl-beta-glucosaminidase) showed a progressive decrease. Alkaline phosphatase, alpha-glucosidase, and N-acetyl-beta-glucosaminidase accumulated in the medium throughout the experimental period to give a medium:tissue distribution ratio of between 2 and 9. Leucyl-beta-naphthylamidase had a medium:tissue ratio of 140 after 48 hours of culture suggesting a selective secretion of this enzyme by the tissue.

Adult↗