Search PubMed⌕ Search

Biomedical subjects

D R Johnson

Publications and source records attributed to D R Johnson.

At least 289 records · Page 16Linked to original sources
PubMed1976

The interfrontal bone and mutant genes in the mouse.

The relationship between corrected skull width and the presence and size of an interfrontal bone is discussed with regard to the effect of certain mutant genes in the mouse known to affect the development of the neural tube. All genes reviewed which increase the incidence of the interfrontal bone and affect the neural tube also change the proportions of the adult skull.

Animals↗
PubMed1976

Crowding and human reproduction.

Studies of crowding in lower animals repeatedly demonstrate that compressed living conditions depress the ability of the species to reproduce. In a sample of 470 urban Toronto women we examined the effect of neighborhood and household crowding on the probability of a pregnancy and on the probability that any given product of the pregnancy will not survive until one year of age. Crowding did not influence fertility nor fetal and infant survival within the range of crowding found in this sample. If crowding has any influence on reproduction it would more profitably be investigated beyond the range of living density and housing markets found in North American urban areas.

Abortion, Legal↗
PubMed1975

Rapid identification of group B streptococci by counterimmunoelectrophoresis.

Beta-hemolytic streptococcal isolates have been examined by counterimmunoelectrophoresis (CIE) with group B antiserum to determine whether this techinque is of value in the rapid identification of group B strains. Ninety stock cultures and 100 clinical isolates of beta-hemolytic streptococci including representatives of groups A, D, C, G, and B were inoculated into Todd-Hewitt broth; after incubation at 37 C for 1, 2, 3, and 4 h, aliquots of the whole broth cultures were removed and tested by CIE. Antigen was not regularly detected in the 1-, 2-, and 3-h samples, but after 4 h all 126 group B streptococcal strains identified by the capillary precipitin reaction gave CIE precipitin bands with group B antiserum. None of the 58 non-group B strains gave precipitin reactions with this antiserum. Cerebrospinal fluid from an infant with group B streptococcal meningitis and peritoneal fluid from a patient with group B streptococcal peritonitis had free group B antigen detected by the CIE technique. CIE of broth cultures and direct body fluids appears to be a rapid and sensitive method for the identification of group B streptococcal strains.

Adult↗
PubMed1975

Endocrinological findings in sterile pink-eyed mice.

Mice homozygous for rho-25h, a mutation at the pink-eye locus, are small, nervous and male sterile, with abnormal sperm morphology: females have very low fecundity. Evidence is presented that in both sexes the pars nervosa of the rho-25h/rho-25h pituitary contains degenerating nerve axons, that the hypothalamus has a reduced binding capacity for oestradiol-17 beta and that thyroid iodine binding is reduced. No changes were observed in the anterior pituitary. In rho-25h/rho-25h females, the uterus is threas-like and unresponsive to oestradiol, and the ovaries are small with many abnormal follicles. Possible modes of action of the rho locus are duscussed with reference to this and pre-existing data on the rho phenotype.

Animals↗