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Biomedical subjects

R Griffiths

Publications and source records attributed to R Griffiths.

70 records · Page 4Linked to original sources
PubMed1976

Effect of induced elevated plasma levels of homocystine and methionine in rats on collagen and elastin structures.

Young growing rats were intraperitoneally injected with mixtures of homocystine and methionine for several weeks. The growth of the animals was inhibited. After 3 weeks 25% of the rats died and isolation of tail tendon collagen and aorta elastin showed that these proteins were deficient in chemical cross-links. Seventy-five % of the rats survived further injections for another 3 weeks and isolated collagen and elastin were found to be normal in cross-linking. The variability in susceptibility of these rats to homocystine-methionine treatment is discussed in relationship to human homocystinuria. It is speculated that the variability is due to variability in in vivo homocysteine levels.

Animals↗
PubMed1975

Experimental models for the modification of human drug self-administration: Methodological developments in the study of ethanol self-administration by alcoholics.

Experimental studies of human ethanol self-administration are reviewed, and a description is provided of the procedural evolution that has oc-urred in the experimental study of the determinants of human ethanol self-administration. Human experimental models of alcoholism have been established within residential laboratories which permit chronic availability of ethanol to volunteer alcoholic subjects. Experimentation within such environments has progressed from observational and descriptive studies of experimental intoxication to studies that manipulate experimental variables so as to modify (reduce) ethanol self-administration by alcoholic subjects. To observe systematic effects of manipulated variables it has been necessary to develop sensitive baselines of ethanol self-administration. When ethanol intake has been relatively unrestricted, wide spontaneous fluctuations have made difficult the evaulation of manipulated variables. When a variety of restrictions on ethanol availability have been imposed, sensitive self-administration baselines have been established which have permitted the direct experimental assessment of some of the determinants of ethanol self-administration. Six methodological principles are suggested for enhancing the information yield of future research on the determinants of ethanol self-administration. The same general methodology is suggested for research with other varieties of drug self-administration.

Administration, Oral↗
PubMedDate not supplied

Effect of ethanol self-administration on choice behavior: money vs. socializing.

Volunteer chronic alcoholic subjects were exposed to a discrete-trail choice procedure within a residential research setting. Twelve daily trials occurred at 20 min intervals. In each trial a subject chose between 2 mutually exclusive options involving either receipt of money or the opportunity for socializing. The effect of ethanol self-administration was evaluated by requiring randomly over days that a subject consume either 8 drinks of orange juice or 8 drinks of ethanol (89.12 g ethanol total). For all 4 subjects, the mean rate of choosing socialization over money was significantly greater on sessions involving ethanol self-administration than on sessions involving orange juice self-administration.

Adult↗
PubMedDate not supplied

Breast skin temperature rhythms in relation to ovulation.

Breast skin temperatures have been monitored at 30-min intervals throughout wake-span for the whole or part of the menstrual cycle of women aged 20-37 years using both manual and automatic (chronobra) methods of measurement. Circadian breast skin temperature rhythms have been mathematically characterized and rhythm parameters assessed in relation to the estimated time of ovulation. Data generally indicate that there is a peri-ovulatory rise in breast temperature. Computer simulation and practical experiments, based on changes in the residual sums of squares from target values obtained for days in the cycle prior to ovulation, have indicated that this peri-ovulatory increase in temperature is possibly detectable within 24 h. The use of the chronobra and associated statistics may be of value in signalling the onset of the infertile phase of the menstrual cycle.

Adult↗