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Biomedical subjects

R Griffiths

Publications and source records attributed to R Griffiths.

At least 181 records · Page 10Linked to original sources
PubMed1977

The molecular defect in a case of (cystathionine beta-synthase)-deficient homocystinuria.

1. Cystathionine beta-synthase activity isolated from fibroblast cultures obtained from the skin of a normal and a homocystinuric individual were both cross-reactive with normal human liver cystathionine beta-synthase antibody. 2. Isoelectric focusing revealed a substantial difference in the isoelectric points of the normal and abnormal fibroblast enzymes. 3. Treatment of purified samples of normal and abnormal fibroblast enzymes with sodium dodecylsulphate followed by polyacrylamide gel electrophoresis indicated that both normal and abnormal enzymes were composed of two sub-units of molecular weights 53000 and 70000. 4. A combination of urea and sodium dodecylsulphate treatment revealed that the respective 53000 molecular weight sub-units were different. 5. It has been concluded that the molecular defect in the case of pyridoxine non-responsive homocystinuria examined in the present investigation arises as a result of an alteration in the structural gene which codes for the lower molecular weight sub-unit of cystathionine beta-synthase.

Cross Reactions↗
PubMed1976

Studies on the use of skin fibroblasts for the measurement of cystathionine synthase activity with respect to homocystinuria.

The levels of cystathionine synthase have been examined in cultured skin fibroblasts obtained from a patient suffering from pyridoxine-non-responsive homocystinuria and compared with the normal and heterozygous states. Levels of synthase activity were found to vary with time in culture and composition of culture media. The physical properties of normal and abnormal synthase activities were markedly different. It has been concluded that caution has to be exercised when using cell culture methods for the purpose of defining normal, heterozygous and homozygous states with reference to homocystinuria.

Adolescent↗
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↗