Showing papers by "French Institute of Health and Medical Research published in 1973"

Evidence of testicular activity in early infancy

Abstract: Plasma testosterone (T) was measured by a sensitive radioimmunoassay method in 143 normal newborns and infants. In cord blood T levels are significantly higher in male than in female newborns. In male infants there was an increase of T concentration from birth to the 2-3th months of life, followed by a gradual decrease. After the 7th month values observed reached those of prepubertal boys. In females the pattern was very different. T levels dropped rapidly from birth to the second week of life reaching values similar to those of prepubertal girls.

Total and Unbound Testosterone Levels in the Newborn and in Normal and Hypogonadal Children: Use of a Sensitive Radioimmunoassay for Testosterone

Abstract: A sensitive and reliable radioimmunoassay combined with celite column chromatography for specific determination of plasma testosterone (T) is described. The percentage binding was measured by equilibrium dialysis. In 28 normal newborns, total T concentration is significantly higher in male (68.1 ± 59.5) than in female newborn infants (12.0 ± 6.2) while binding of T increases rapidly after birth. Although there is no sex difference in TeBg capacity, levels of unbound T in the first two weeks of life are still significantly higher in male than in female infants. There was no sex difference in 62 normal prepubertal children studied, the total T concentration being 6.62 ± 2.46 and 6.58 ± 2.48 ng/100 ml in boys and girls, respectively; the binding of T and unbound T levels were identical in both. In 17 patients with Turner syndrome, total T concentration (13.6 ± 3.1 ng/100 ml) was significantly higher than in prepubertal children and increased (21.5 ± 2 ng/100 ml) under moderate estrogen therapy while the perc...

Electronic coupling between neurons in the rat lateral vestibular nucleus.

Abstract: Correlation of morphological and electrophysiological data strongly suggest that in rat, the giant cells of the lateral vestibular nucleus (L.V.N.) are electrotonically coupled. 1. in addition to “active zones” large terminals synapsing on the perikaryon and/or the main dendritic trunk of the cells bear “gap” junctions which are interpreted as low electrical resistance pathways between neurons. 2. electrical activity of the giant cells was recorded intracellularly as the vestibulo-spinal tract was stimulated. Graded antidromic stimulation produced graded antidromic depolarizations (G.A.Ds) in 69% of cells with high threshold axons. 3. the latency of the G.A.Ds was too short to allow for chemical transmission through afferents or recurrent collaterals. 4. collision experiments demonstrated that directly evoked spikes blocked the antidromic spikes but did not block the G.A.Ds which thus were accounted for by activation of cells others than the impaled ones. 5. lesion experiments indicated that afferent fibers from the spinal cord terminate exclusively in the dorsal part of the L.V.N. Since G.A.Ds were recorded all throughout the nucleus, they were not excitatory post synaptic potentials (EPSPs) from spinal afferents. 6. when the strength of the spinal cord stimulation was increased EPSPs were also generated but they were distinct from the G.A.Ds by their latencies, time course and maximum amplitude. 7. since no direct contact is observed between neurons it is inferred that, as in other documented cases, coupling between giant cells is mediated by way of presynaptic fibers.

In vitro synthesis of müllerian-inhibiting hormone by seminiferous tubules isolated from the calf fetal testis.

Abstract: Fetal calf testicular tissue was submitted to microdissection. Whole testicular tissue, isolated seminiferous tubules and interstitial tissue were cultured in association with fetal rat reproductive tracts. Mullerian inhibition was achieved only in explants containing seminiferous tubules. The possibility that the mullerian-inhibiting hormone is produced by the fetal Sertoli cells is suggested. (Endocrinology 93: 829, 1973)

Large-Scale Preparation of Soluble Adenovirus Hexon, Penton and Fiber Antigens in Highly Purified Form

Abstract: A three-step mild procedure is described, that permits isolation of an adenovirus type-2 soluble hexon, penton and fiber antigens in an extensively purified form. This procedure comprises ammonium sulfate precipitation, Sephadex ion-exchange chromatography and adsorption chromatography on an hydroxyapatite column. The final antigen preparations were homogeneous with regard to immunological, electrophoretic and electron microscopic criteria.

[Comparison of the structure of chromatids of Homo sapiens and Pan troglodytes (author's transl)].

Abstract: Prometaphasic chromosomes of man and chimpanzee are compared, using R, Q, T and H-bands techniques. — Six pericentric inversions, one telomeric fusion-translocation, 4 intercalar deletions or insertions, 16 deletions or additions of terminal Q-bands, and an important variation of heterochromatin distinguish the 2 species. — The evolutive role of chromosomal rearrangements separating the 2 species is discussed with particular reference to the formation of human chromosome No 2.- The simultaneous analysis of human chromosomal pathology and of the chromosomal structures in primates should contribute to the understanding of accidental modifications of the genome and to the interpretation of their consequences.

Studies on thymus products. VI. The effects of cyclic nucleotides and prostaglandins on rosette-forming cells. Interactions with thymic factor.

Abstract: Cyclic AMP, its dibutyryl derivative and prostaglandins, PGE1 and PGE2, do not modify the numbers of rosette-forming cells (RFC), but they do alter these cells' sensitivity to in vitro inhibition by azathioprine (AZ) and anti-theta serum (ATS). In thymectomized mice, cyclic nucleotides and prostaglandins mimic the action of the thymic factor contained in thymic extracts and in normal serum, correcting the low spleen RFC sensitivity to AZ and ATS induced by thymectomy. Moreover, the mixture of infraliminal active doses of cyclic AMP and of thymic extracts (or normal mouse serum) also gives this effect. In normal mice, the nucleotides (but not prostaglandins) lower the AZ and ATS sensitivity of RFC, which remains insensitive to thymic extracts. Theophylline and isoproterenol have effects similar to those of cyclic AMP, a result in accord with their postulated interactions with the adenyl-cyclase system. Noncyclic AMP and cyclic GMP show no effect in the RFC assay system at doses 10–100 times higher than active doses of cyclic AMP. Other vasoactive compounds, including epinephrine, phentolamine, propanolol, and angiotensin, do not show any effect on RFC.

Dissociation de deux composantes du comportement chez le rat sous l'effet de psychotropes

Abstract: The “staircase” is a simple and rapid test and was used to study two components of exploratory behaviour in the rat. The scores of rearing and the number of steps climbed during three minutes were recorded. Various psychotropic drugs were tested, which modified these two parameters. Neuroleptic induced a parallel decrease of both, while benzodiazepines, meprobamate, amobarbitone and ethanol decreased the rearing at doses which left the steps climbed unchanged. At high doses, there was a parallel decrease of both parameters. Amphetamine, at lower doses, increased the rearing score alone. The comparison of the studied psychotropic drug effects with those of two muscle relaxants (by a comparison of the slopes of regression lines) suggests that either the observed benzodiazepine effects were only partly due to their myorelaxant action, or, that both myorelaxants have some anxiolytic action. The effect of amphetamine at low doses can be viewed as a demonstration of increased anxiety.