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Biomedical subjects

R D Robinson

Publications and source records attributed to R D Robinson.

88 records · Page 5Linked to original sources
PubMed1978

Prostaglandin metabolism by human testis.

Human testis preparations appear to carry out both the synthesis and turnover of prostaglandins. Prostaglandins and prostaglandin metabolites were extracted from whole tissue. Testis microsomes converted both endogenous and exogenous substrate to prostaglandins. Microsomal prostaglandin biosynthesis was inhibited by indomethacin. Prostaglandin E2-9-ketoreductase was present in both the cytosolic and microsomal fractions of human testis. Prostaglandin metabolism by human testis has not previously been reported.

Aged↗
PubMed1976

Physiological aging of champion runners.

The physiological adjustments to aerobic work (5.6 km/h, up a 9% grade) and to exhausting treadmill work of former champion middle-distance runners were determined in 1971, at ages 47-68 yr, 25-43 yr after their competitive careers in track. In the resting state the former athletes as a group are very much like nonathletes of the same ages. Efficiency in the aerobic walk was the same in both groups and did not change with age in either, but the former athletes on the average performed the walk with less strain as indicated by lower blood lactates, "ventilatory equivalents," and heart rates than nonathletes at corresponding ages. Mean VO2max of the runners declined from 71.4 ml/min-kg-1 in youth to 41.8 at a mean age of 56.6 yr, as compared with mean values of 50.6 and 36.5 ml/min-kg-1 in nonathletes at corresponding ages. VO2max had declined below the average of nonathletic men in only two of the former runners. Mean maximal heart rate declined with age from 186 to 180 in the runners, and from 199 to 186 in nonathletes at corresponding ages. Ventilatory responses of men in both groups were closely related to the increases of blood lactate in both aerobic and maximal work.

Aged↗
PubMed1975

Longitudinal studies of aging in 37 men.

The physiological adjustments of the men to both aerobic (5.6 km/h, up 9% grade), and maximal treadmill work were first determined when they were healthy college students, ages 18-22 yr. They were restudied at ages 40-44, and again at ages 49-53 yr. In the aerobic walk VO2 increased in proportion to weight gain, but efficiency did not change with age. The men who had gained most weight showed the greatest elevations of heart rate, blood lactate and "ventilatory equivalent," and reductions of the "O2 pulse" in the walk. At age 50 mean "O2 pulse" in exhausting work had declined 13%, even though mean maximal heart rate had declined 15 beats/min from values observed in youth. At ages 40-44 yr mean VO2 max had declined 25% to values 12% lower than mean values reported in 1938 for men of this age. Eight of the men imporved an average of 11% in VO2 max between ages 40-44 and 49-53 yr; mean VO2 max of the others continued to decline with age. The five men who improved most had increased their participation in vigorous activities (tennis, squash, skiing, jogging, etc.) and had quit or reduced their smoking.

Adolescent↗
PubMedDate not supplied

Immunodiagnosis of Strongyloides stercoralis infection: a method for increasing the specificity of the indirect ELISA.

Indirect enzyme-linked immunosorbent assay (ELISA) allows sensitive detection of serum immunoglobulin (Ig) G against a soluble extract of Strongyloides stercoralis infective larvae. In this study, 40/40 (100%) human strongyloidiasis sera had high levels of anti-S. stercoralis IgG, but 30/40 (75%) filariasis sera, and 12/40 (30%) necatoriasis sera also had higher levels than control sera from UK residents. In attempts to increase the assay specificity by absorption of cross-reactive IgG, the effectiveness of pre-incubation of sera with extracts of different parasitic nematodes was investigated. One hour of incubation with 20 micrograms/ml aqueous extract of Onchocerca gutturosa absorbed cross-reactive IgG in most filariasis and necatoriasis sera, reducing the proportion with IgG levels above the positivity threshold by more than one-half. Preliminary results suggest that absorption with extracts of other filarial nematodes is equally effective, and that some of the cross-reactive IgG is directed against phosphorylcholine. Cross-reactive IgG in most necatoriasis sera was effectively absorbed with 20 micrograms/ml extract of Necator americanus. Cross-reactive IgG was not effectively absorbed with an extract of Ascaris lumbricoides. Absorption of cross-reactive IgG is an effective means of increasing the specificity of the indirect ELISA, for use in the immunodiagnosis and immuno-epidemiology of S. stercoralis infection.

Absorption↗
PubMedDate not supplied

Humoral responses in human strongyloidiasis: correlations with infection chronicity.

Strongyloides stercoralis L3-specific antibody isotype responses amongst individuals with known long-standing (28-46 years) infection were compared with those of 'young' (6-29 years of age) and 'old' (30-80 years of age) infected individuals from an endemic Jamaican population. Characterization of age-dependent isotype patterns in the endemic community showed that immunoglobulin (Ig) G1 responses were significantly inversely correlated with age. Additionally, a trend towards lower IgE levels in the older age group was observed. Comparison with responses amongst known chronically infected individuals showed that IgG1 and IgE levels were similar to those of the 'old' endemic group, but were significantly lower than those of the 'young' group. In contrast, IgA levels were similar in both endemic groups, but were elevated in chronically infected individuals. IgG4 levels were similar in all groups studied. These findings suggest that age correlates with infection chronicity in communities endemic for S. stercoralis, and that individuals acquire infection early in their lives and remain infected into adulthood. Early and sustained upregulation of IgG4 may facilitate the establishment of infection and, in combination with developing IgE hyporesponsiveness, may promote chronic asymptomatic strongyloidiasis. Conversely, upregulated IgA may be involved in controlling chronic infection levels which are reflected in reduced IgG1 production.

Adolescent↗
PubMedDate not supplied

Effects of diet on mercury metabolism and excretion in mice given methylmercury: role of gut flora.

Mice fed either (1) a pelleted rodent diet, (2) evaporated milk, or (3) a synthetic diet (high protein, low fat) exhibited different rates of whole body mercury elimination and fecal mercury excretion after exposure (per os) to methylmercuric chloride. The percentage of the total mercury body burden present as mercuric mercury was highest (35.3%) in mice fed the synthetic diet (which had the highest rate of mercury elimination) and lowest (6.6%) in the animals having the lowest mercury elimination rate (milk-fed mice). Mice fed the synthetic diet had lower mercury concentrations and had a higher proportion of mercuric mercury in their tissues than the mice from the other dietary groups. Treatment of the mice with antibiotics throughout the experimental period to suppress the gut flora reduced fecal mercury excretion and the dietary differences in whole body retention of mercury. Tissue mercury concentrations and proportion of organic mercury in feces, cecal contents, liver, and kidneys were increased by antibiotic treatment of mice fed the pelleted or synthetic diets. These results are consistent with the theory that demethylation of methylmercury by intestinal microflora is a major factor determining the excretion rate of mercury.

Animal Feed↗