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Biomedical subjects

J Bernal

Publications and source records attributed to J Bernal.

At least 145 records · Page 8Linked to original sources
PubMed1978

[The experience in dental education of Cayetano Heredia University of Peru].

This article describes the educational experience gained in the dentistry program of Cayetano Heredia University in Peru. The programs for professional and auxiliary personnel training were drawn up after analyzing the health needs of the population and the services required to meet them, which resulted in the elaboration of an original methodology and taxonomy. Learning is an integral experience, one that takes place in the dental clinic, the hospital, and the community. The curriculum includes the following components: units for the intensive learning of clinical functions, fewer preclinical activities, clinical training with the ongoing assistance of auxiliary staff, extended interaction with marginal urban communities, rural internships, and hospital externships. A summary account is given of the gains made, the difficulties encountered, and plans for devising in-service teaching approaches that more effectively meet the needs of the community.

Community Dentistry↗
PubMed1977

The action of thyroid hormone.

Thyroid hormone affects both developmental and metabolic processes. It has a relatively specific effect on the synthesis of a number of enzymes and other proteins. The fundamental cellular mechanism of action seems to be at the level of genetic regulation. It involves interaction with nuclear receptors, leading to an activation of the protein synthesizing machinery. How binding to receptors is coupled to genetic activation is completely unknown. At least part of the metabolic effects of thyroid hormone could be mediated through an interaction with mitochondria and cell membrane, and with some enzymatic systems such as adenylcyclase.

Animals↗
PubMed1977

Thyroid hormone receptors: release of receptor to the medium during in vitro incubation of isolated rat liver nuclei.

Isolated rat liver nuclei show a substantial amount of T3 receptor release to the medium during in vitro incubation. This has been shown to be a general feature of nuclei compared after several methods of isolation and incubation. About 50% of nuclear receptors are released to the medium when incubated in sucrose-MgCl2-Tris, pH 7.85, for 2 h at 20 C.DNA, histones, and non-histone proteins (NHP) are also released. CaCl2 inhibits about 90% of the release of DNA and histones, but has less effect on inhibiting leakage of NHP and nuclear T3-binding protein (NTBP). The highest leakage for each fraction was found when incubating nuclei in the presence of EDTA. The receptor released to the medium has an affinity virtually identical to the receptor remaining in the nuclei. At least 1 mM dithiothreitol is needed to avoid degradation of the receptor. The NTBP has a sedimentation constant of 4.5 S when studied in low ionic strength gradients. Increasing KCl concentration decreases progressively its sedimentation constant, and in gradients containing 0.4 M KCl the receptor sediments as a single peak of 3.4 S. Since release of receptor to incubation medium decreases free T3 concentration, it must be taken into account in calculating receptor affinity. Total nuclear capacity in vitro is obviously underestimated, unless receptor released to medium is measured. Receptor exchange between cytosol and nucleus may be of physiologic significance.

Animals↗
PubMed1975

Effect of the exposure to cold on the extrathyroidal conversion of L-thyroxine to triiodo-L-thyronine, and on intramitochondrial alpha-glycerophosphate dehydrogenase activity in thyroidectomized rats on L-thyroxine.

Thyroidectomized rats have been injected daily with 125-I labelled L-thyroxine (T4) and, once isotopic equilibrium was attained, divided into cold-exposed (4-10 degrees C) and control (21-24 degrees C) groups, the daily T4 administration being continued till the end of the experiment. Fourteen days after onset of cold exposure, the total I of different organs and of the carcass was determined and the tissues submitted to extraction and paper chromatography for the separation of T4 and T4-derived I-containing compounds. The Activity of intramitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) was measured in kidneys and liver. It was found that the total amount of I was intensely decreased in all samples from cold-exposed animals. The proportion of this Iwhich was non-extractable was the same, in all tissues, for cold-exposed and control rats. The % of extractable tissue radioactivity in the form of T4 was decreased, and that found as T4-derived T3 was increased, in all samples from cold-exposed animals. The T3/T4 ratio was increased more than two-fold in all tissues studied. The concentration of T4 decreased significantly in all tissues, whereas the concentration of T3 in tissues of cold-exposed rats did not decrease. It actually increased in kidneys and lungs, and remained the same in liver and carcass. Despite the decrease in the concentration of T4 in the kidneys, alpha-GPD activity was increased in this tissue, where the concentration of T3 was increased. No change in the alpha-GPD activity was found for the liver, where the concentration of T3 was the same for cold-exposed and control rats. Thus, it appears likely that the conversion of T4 AND T3 is increased by the exposure to cold of thyroidectomized rats on a constant dose of T4.alpha-GPD activity in a given tissue appears to be more closely related to the concentration of T3, than to that of T4.

Animals↗
PubMed1971

[Fetal momstruosity].

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Abnormalities, Severe Teratoid↗