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Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

At least 253 records · Page 14Linked to original sources
PubMed1983

Effects of L-thyroxine treatment on pituitary GH content of adult rats with neonatal thyrotoxicosis.

Rats receiving large doses of thyroxine (30 micrograms/5 doses) during their first days of life develop an apparently permanent alteration of the hypothalamus-pituitary-thyroid complex. This neonatal thyrotoxicosis has been called neo-T4 syndrome. A state of permanent but not very severe hypothyroidism seems to be induced, accompanied by a decrease in pituitary GH content at least until day 22. In this work, growth hormone content has been measured by a specific radioimmunoassay in the anterior pituitary of 45 and 78 day old neo-T4 and control (saline-injected) rats. GH content of the adult neo-T4 treated animals was significantly lower than that of the adult controls. Administration of different doses of T4 (1.7 micrograms/100 g body weight/3 doses or 2.5 micrograms/100 g body weight/8 doses, to 70 day old rats, and 5 micrograms/100 g body weight/3 doses to 42 day old rats) to adult neo-T4 rats did not alter these decreased pituitary GH levels. This differs from hypothyroid rats, in which T4 administration has been shown to increase pituitary GH content. A third approach was to thyroidectomize neo-T4 and control rats and administer 5 micrograms T4/100 g body weight, which produced the same increase in pituitary GH in both groups of animals. These results seem to indicate that changes in pituitary GH content of neo-T4 rats are not due to hypothyroidism. Thus, it would appear that treatment with large T4 doses during the early perinatal period not only deranges the hypothalamic-pituitary-thyroid axis but other pituitary functions as well.

Animals↗
PubMed1982

[Liver glycogen, blood glucose, somatotropic hormone, and hypophyseal thyrotropin in neonatal rats treated with cortisol and in malnourished ones].

A population of rats treated with a single dose of cortisol on their first day of life and a population of rats underfed since day sixteen of gestation until sacrificed have been studied. Body, brain and liver glycogen content have been measured at eight, twelve and twenty-two days of life and compared to controls of the same age. Pituitary growth hormone and thyrotrophin content have also been measured in the same population of animals and at the same stages of life. Results are compared to those found in "neo-T4" rats -- which receive 30 micrograms T4 in 5 doses during the first days of life -- at the same ages.

Animals↗
PubMed1981

High resolution radioautography of central dopaminergic fibers labelled in vitro with [3H]dopamine or [3H]norepinephrine.

An original method is reported for the radioautographic visualizing of dopaminergic axons terminals in the rat central nervous system. This method is based on an in vitro labelling with either tritiated norepinephrine or dopamine under conditions of specificity previously established by fluorescence histochemistry. The immobilization of [3H]catecholamines in their sites of uptake and storage during post-fixation for electron microscopic processing was ensured by the use of osmic acid vapours instead of osmic acid solution. Selective labelling of the dopaminergic fibers may be achieved throughout large brain sections and the technique should be applicable to human biopsy material.

Animals↗
PubMed1981

Effect of topically-applied solutions of iodine, sodium fluoride, or chlorhexidine on oral bacteria and caries in rats.

Antibacterial levels of iodine, chlorhexidine or sodium fluoride were topically applied to the molar teeth of rats. The effect of these agents on buccal and sulcal caries, as well as on certain oral bacterial populations was assayed. All three agents exerted a significant cariostatic effect which was site specific. Buccal caries incidence and reductions appeared correlated to S. mutans counts, while sulcal caries was better correlated to total cultivable counts. These studies suggested that the simultaneous application of iodine and NaF might exert an additive cariostatic effect.

Administration, Topical↗
PubMed1979

[Radioautographic identification of dopaminergic axons in the rat CNS. In vitro marking with tritiated dopamine or noradenaline].

A new radioautographic technique for the visualization of central dopaminergic fibers is described. This technique is based upon in vitro uptake of triatiated norepinephrine or tritiated dopamine in the presence of monoamine oxidase inhibitor and specific uptake inhibitor in noradrenergic fibers. After a short step in glutaraldehyde, the use of osmium vapours as a fixative, instead of osmic acid immersion, allows a satisfactory retention of triatiated amines within dopaminergic fibers.

Animals↗
PubMed1979

Double labelling of blanched neurons in the central nervous system of the rat by retrograde axonal transport of horseradish peroxidase and iron dextran complex.

The retrograde axonal transport of an iron-dextran complex leads to a labelling of neural cell bodies in the central nervous system (CNS) of the rat. This tracer and horseradish peroxidase (HRP) can both be demonstrated histochemically in same cell bodies of intralaminar thalamic neurons in the central lateral nucleus, after injection of iron-dextran in the striatum and injection of HRP in the motor cortex. This is made possible by processing the sections first for HRP and then for ferric ions by Perl's reaction. This method allows an accurate demonstration of divergent axonal projections and is compatible with cytoarchitectonic studies on the same sections.

Animals↗