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Biomedical subjects
Publications and source records attributed to J Hayward.
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Five-day old rats subjected to short-term (2-day) lead exposure by gastric gavage of aqueous lead acetate at the highest non-lethal dosage (1mgPb/g body weight/day) developed a hemorrhagic encephalopathy. Capillaries and microvessels isolated from brains of these rats showed abnormal morphology consisting of an increased number of irregularly dispersed endothelial nuclei and swollen, vacuolated endothelial cells. Lead was concentrated in isolated brain capillary-microvessel fractions, as demonstrated by both atomic absorption and 210Pb tracer methods. When lead exposure was continued for 20 days (at the maximal dosage regime compatible with a 60% survival rate), the rats recovered from the initial encephalopathy and capillaries and microvessels isolated from brains of these rats appeared morphologically normal. This recovery occurred despite continued high levels of lead in the blood and in the isolated capillary-microvessel fractions, suggesting that, as capillary endothelial cells mature, they are able to adapt to the presence of large amounts of lead.
This study has been conducted on forty-five Asiatic skulls and sixty-two mixed skulls of black and white Americans to determine the anteroposterior relationship of the mandibular foramen. The mean size of the anterior dimension was greater than the mean size of the posterior dimension of the ramus in all instances. The mandibular foramen was found to be located in the third quadrant anteroposteriorly. The lingula was located just anterior to the mandibular foramen. There was no right- or left-side dominance in the ramus size and position of the mandibular foramen. No appreciable difference was noted in the location of mandibular foramen in the two groups studied.
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A Group A variant-like antigen has been detected in streptococci belonging to Groups D, E, G, M, and N. In Groups D and N the variant-like antigen was located in the streptococcal cell walls. In two strains of Group N streptococci (C559 and B209) the cell walls were chemically different and serologically distinct. In strain C559 N-acetylgalactosamine, and in strain B209, N-acetylglucosamine were the major determinants of serological specificity. The cell walls of strain C559 contained at least three serologically reactive components: a rhamnose-containing fraction that precipitated with an antiserum to Group A-variant carbohydrate; a strain-specific polysaccharide composed of galactosamine and glucosamine, both in the N-acetylated form and probably polymerized with an unidentified phosphorylated substance; and a component of unknown composition serologically related to a Group D streptococcus strain C3 (S. durans). An analogy is drawn between the cell wall structure in streptococcus and Salmonella.
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