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Biomedical subjects

G Thomas

Publications and source records attributed to G Thomas.

At least 829 records · Page 46Linked to original sources
PubMed1976

[Technique for allogeneic transplantation of knee joint (author's transl)].

Ever since Lexer's first attempts to remedy destroyed knee-joints by transplanting homioplastic material, the cup joint transplantation as developed by Pap and Krompecher has proved to be expedient and suitable thanks to the recent work performed by Wolkow. In order to assure that the process is safe from the mechanical standpoint, i.e. guarantee an accurate fit of the transplant to the recipient joint portion, in particular in the femur condyle area, the author has developed a method whereby the joint cups are cut rut of the donor material in accordance with pre-produced patterns and the oecipient joint portion is shaped to the correct form by means of similar patterns produced on the basis of X-rays.

Adolescent↗
PubMed1976

Fluorophotometry and the rate of aqueous flow in man. I. Instrumentation and normal values.

A new objective fluorophotometer, based on a previous model but with changes in electronic circuitry, was designed and built. The fluorometric method was applied to 38 normal eyes to obtain the aqueous outflow rate and fluorescein decay constant. Aqueous outflow rate has a direct correlation with the anterior chamber depth and an inverse correlation with age. The aqueous flow rate is higher in whites than in blacks, but in our sample, mean pressure was lower in whites. Acetazolamide decreases the aqueous flow rate and the fluorescein constant; the mean decrease in 10 eyes of 5 patients was approximately 38% and 22%, respectively. Fluorophotometry gives a higher value for the aqueous outflow rate than that calculated by tonography.

Acetazolamide↗
PubMed1976

Alteration of polynucleotide secondary structure by ribosomal protein S1.

Ribosomal 30S protein S1 causes disruption of the secondary structure of certain pyrimidine-containing polynucleotides. Helical poly(U), poly(C, U), and neutral and acidic poly(C) are stoichiometrically converted by S1 to structures indistinguishable from their partially or completely thermally denatured forms, as revealed by circular dichroism. Of the several double- and triple-stranded helical polynucleotides tested that contain one polypurine strand and at least one polypyrimidine strand, only the conformation of the DNA.RNA hybrid, poly(A)-poly(dT), is perturbed. In the presence of S1, this hybrid undergoes a transition to a new structure that has a circular dichroism spectrum unlike either the native or thermally denatured forms. Intercalated ethidium bromide is released from poly(A)-poly(dT) by S1, confirming the occurrence of a conformational rearrangement. The translation inhibitor, autintricarboxylic acid, completely inhibits the action of S1 on polypyrimidines, but has no effect on the conformational perturbation of poly(A(-poly(dT). The possible relation between these observations and the biological function of protein S1 is discussed.

Circular Dichroism↗
PubMed1976

Defective thymine dimer excision by cell-free extracts of xeroderma pigmentosum cells.

Crude extracts of normal human diploid fibroblasts and of human peripheral blood lymphocytes excise thymine dimers from purified ultraviolet-irradiated DNA, or from the DNA presumably present as chromatin in unfractionated cell-free preparations of cells that had been labeled with [3H]thymidine. Extracts of xeroderma pigmentosum cells from complementation groups A, C, and D also excise thymine dimers from purified DNA, but extracts of group A cells do not excise dimers from the DNA of radioactively labeled unfractionated cell-free preparations.

Cell Line↗
PubMed1976

Alpha-fetoprotein levels in maternal plasma and amniotic fluid during prostaglandin-induced mid-trimester abortions: the relation to fetal distress and death.

Alpha-fetoprotein (AFP) levels were measured in both plasma and amniotic fluid during 43 abortions induced with prostaglandin F2alpha (PGF2alpha) and their relationship to the induction-abortion interval and signs of fetal distress or intrauterine death examined. The mean plasma AFP levels showed a progressive rise after PGF2alpha administration but abnormally high levels were found infrequently until the time of delivery. Feto-maternal bleeding could explain the abnormally high plasma AFP levels which occurred early in a few cases. A shorter induction-abortion interval was found in patients with normal plasma AFP levels. Neither fetal distress nor intrauterine death were associated with abnormally high plasma AFP levels. No change in AFP levels in amniotic fluid was found.

Abortion, Induced↗
PubMed1976

Endemic tropical sprue in Rhodesia.

The existence of tropical sprue in Africa is controversial. In this paper we present 31 cases seen in Rhodesia over a 15 month period. They have the clinical features, small intestinal morphology, malabsorption pattern, and treatment response of tropical sprue. Other causes of malabsorption, and primary malnutrition, have been excluded. The severity of the clinical state and intestinal malabsorption distinguish these patients from those we have described with tropical enteropathy. The previous work on tropical sprue in Africa is reviewed and it is apparent that, when it has been adequately looked for, it has been found. It is clear that the question of tropical sprue in Africa must be re-examined and that it existence may have hitherto been concealed by the assumption that primary malnutrition is responsible for the high prevalence of deficiency states.

Adolescent↗
PubMed1976

Tropical enteropathy in Rhodesia.

Tropical enteropathy, which may be related to tropical sprue, has been described in many developing countries including parts of Africa. The jejunal changes of enteropathy are seen in Rhodesians of all social and racial categories. Xylose excretion, however, is related to socioeconomic status, but not race. Upper socioeconomic Africans and Europeans excrete significantly more xylose than lower socioeconomic Africans. Vitamin B12 and fat absorption are normal, suggesting predominant involvement of the proximal small intestine. Tropical enteropathy in Rhodesia is similar to that seen in Nigeria but is associated with less malabsorption than is found in the Caribbean, the Indian subcontinent, and South East Asia. The possible aetiological factors are discussed. It is postulated that the lighter exposure of upper class Africans and Europeans to repeated gastrointestinal infections may accound for their superior xylose absorption compared with Africans of low socioeconomic circumstances. It is further suggested that the milder enteropathy seen in Africa may be explained by a lower prevalence of acute gastroenteritis than in experienced elsewhere in the tropics.

Humans↗
PubMed1976

Anaphylactoid responses of two types of genetically different rats to horse serum and yeast.

Rats selectively bred for non-reactivity to clinical dextran (NR rats) fail to exhibit the anaphylactoid reaction to systemic baker's yeast or horse serum. Rats which respond with an anaphylactoid reaction to clinical dextran (R rats) react to baker's yeast but do not react to horse serum. The widespread oedema produced in R rats by systemic baker's yeast provides yet another clear method of differentiating them from NR rats.

Anaphylaxis↗
PubMed1975

Structure of coat proteins in Pf1 and fd virions by laser raman spectroscopy.

Rama spectra of filamentous bacterial viruses are dominated by scattering from vibrations of the protein capsomers. The amino acid compositions of coat proteins in Pfl and fd strains are recognized by their different side-chain vibrational frequencies. However, the conformationally sensitive amide frequencies indicate that Pfl and fd coat proteins have the same alpha-helicial secondary structures. Viral DNA backbones do not exhibit the A-type geometry.

Animals↗