Showing papers by "Université libre de Bruxelles published in 1971"
TL;DR: Injected frog eggs and oocytes provide a very sensitive assay system for the identification of messenger RNA and permit the study of translational control in living cells.
Abstract: Injected frog eggs and oocytes provide a very sensitive assay system for the identification of messenger RNA and permit the study of translational control in living cells. The translation of each haemoglobin messenger RNA molecule once every 5–10 minutes for at least 24 hours makes it possible to recognize less than 1 ng of this messenger RNA.
718 citations
TL;DR: This chapter discusses the action of thyrotropin on thyroid metabolism, which involves the formation of thyroid hormones from iodide and tyrosines and the secretion of these hormones, and induces, after a delay, the growth of thyroid tissue.
Abstract: Publisher Summary This chapter discusses the action of thyrotropin on thyroid metabolism. Growth and function of the thyroid are mainly controlled by the level of thyrotropin (TSH) concentration in the plasma. The principal element of this control, the action of TSH on its target, the thyroid follicular cell, has been investigated intensively during recent years. TSH activates rapidly the steps of thyroidal iodine metabolism—that is, the formation of thyroid hormones from iodide and tyrosines and the secretion of these hormones, and induces, after a delay, the growth of thyroid tissue. Among the various systems available for the study of the interaction of a tropic hormone with its target cell, the thyroid and TSH present several advantages and disadvantages. The specialized metabolism of the follicular cell, the metabolism of iodine, is easily studied with the various radioisotopes of iodine. Thyroid tissue is very resistant to adverse conditions, which explains the great stability and the great variety of in vitro thyroid systems.
319 citations
TL;DR: Ultraviolet mutations are affected to a small extent by the red + function of λ phage whereas this function seems to play an important role in the spontaneous mutation process.
269 citations
TL;DR: The temporal behaviour of a chemical system beyond a non-equilibrium unstable transition is analysed and compared to the behaviour of Volterra-Lotka type systems and certain types of biological rythmic phenomena are discussed.
174 citations
01 Jan 1971
173 citations
TL;DR: It is concluded that when injected into a living cell, the 9 s RNA is fairly stable and has the properties of a haemoglobin messenger.
158 citations
TL;DR: The theory of fluctuations is extended to nonlinear systems far from equilibrium, in which the departure from the steady state is governed by large fluctuations of macroscopic size, while small thermal fluctuations are still described by a generalization of Einstein's equilibrium theory.
Abstract: The theory of fluctuations is extended to nonlinear systems far from equilibrium. Systems whose evolution involves two separate time scales, e.g., chemically reacting mixtures near a local equilibrium regime, are studied in detail. It is shown that the usual stochastic description of chemical kinetics based on a “birth and death” model is inadequate and has to be replaced by a more detailed phase-space description. This enables one to develop for such systems a plausible mechanism for the emergence of instabilities, in which the departure from the steady state is governed by large fluctuations of macroscopic size, while small thermal fluctuations are still described by a generalization of Einstein's equilibrium theory. On the other hand, far from a local equilibrium regime, infinitesimal fluctuations may increase and attain macroscopic values. In this case the system evolves to a state of “generalized turbulence”, in which the distinction between macroscopic averages and fluctuations becomes meaningless.
151 citations
TL;DR: In this paper, a sample of some 7500 K − meson captures at rest on hydrogen in emulsion giving rise to charged Σπ pairs was used to determine r, the decay branching ratio of the Σ + hyperon, λ, the ratio of Σ − to Σ+ hyperon production, τ Σ−, the lifetime of the ǫ − hyperon and C 10 −12 sec.
111 citations
TL;DR: The diffusion coefficient of dissolved monomeric silica in seawater of 36.1% salinity has been determined at 25° C by the diaphragm cell method.
Abstract: THE diffusion coefficient of dissolved monomeric silica in seawater of 36.1% salinity has been determined at 25° C by the diaphragm cell method. The value of the coefficient D is 1.0±0.05×10−5 cm2 s−1. The value at seafloor temperatures is probably about 0.5×10−5 cm2 s−1 and is consistent with empirical diffusion coefficients of silica in pore water-sediment systems of the order of 0.1 to 0.3×10−5 cm2 s−1, when corrections for porosity are made.
110 citations
103 citations
TL;DR: In skin tissue culture, living cells were filled with dark granules showing an aspect characteristic of the “I-cell” phenotype, andFindings that distinguish this clinical pattern from the typical mucopolysaccharidoses are discussed.
TL;DR: The evidence supporting the validity of the cAMP model for TSH and thyroid is proposed to be summarized, then data is presented on the mechanism of TSH-induced thyroid secretion.
Abstract: Only five years ago, the cyclic 3‘,5‘-AMP model of hormonal action was not generally believed to apply to TSH t and thyroid.’-* Since then, overwhelming evidence has been accumulating in favor of this hyp~thes is .~ The cAMP concept, as it may apply to the thyroid is summarized in FIGURE 1. Four criteria have been proposed by Sutherland and his colleagues to test the validity of this model for a particular hormonal action: (1) the hormone should activate adenyl cyclase in homogenates of the target tissue or/and in sedimentable fractions of such homogenates; (2) the hormone should increase the cAMP content of intact target cells; (3) liposoluble derivatives of CAMP, such as DBcAMP, or even cAMP itself, should mimic the hormonal action on the target tissue; and (4) inhibitors of cAMP intracellular catabolism, i.e., of cAMP phosphodiesterase( s) , such as the methylxanthines, should reproduce or potentiate the hormonal effects. For each hormonal effect, the kinetics and the concentration-response relationships should be consistent with the model. In this article we propose to summarize briefly the evidence supporting the validity of the cAMP model for TSH and thyroid, then to present data, mostly from our laboratory, on the mechanism of TSH-induced thyroid secretion.
TL;DR: Under adequate treatment the neurological symptoms disappeared in all cases and the importance of this factor in the pathogenesis of hyponatraemia may be explained by sodium deficiency in the diet, the absorption of large quantities of water, and the possible role of inappropriate secretion of antidiuretic hormone in these alcoholic patients.
TL;DR: Adult rats, previously maintained on a chow containing 48 p.
TL;DR: In this paper, the authors investigated the question of what conditions must satisfy two discrimination indices to yield identical scales and the usual questions of existence, uniqueness, and construction of solutions to Fechner's Problem.
TL;DR: The results show that frog eggs and oocytes possess an unused capacity for translating injected messenger RNA, and that the amount of this spare capacity can be determined by the construction of messenger RNA saturation curves.
TL;DR: The involvement of cyclic AMP as mediator of cholinergic agents and pancreozymin, the relationship between stimulation of secretion and the rate of protein synthesis and the relationship of the phospholipid effect with secretion are discussed.
TL;DR: In this paper, the results of the Prigogine-George-Henin theory of subdynamics are extended to cover more general systems, such as spatially inhomogeneous systems or relativistic systems.
TL;DR: Highly purified k-DNA has been prepared from Crithidia luciliae by a two step procedure, involving differential sedimentation in sucrose followed by banding in a CsCl density gradient.
TL;DR: The behaviour of a chemical system beyond a non-equilibrium unstable transition is analysed in the limit of a large separation of time scales characterizing the individual chemical steps and it is found that the system may exhibit in this limit relaxation, or quasi-discontinuous type oscillations.
TL;DR: In this article, the existence of facies anormaux de magnetite dans la meteorite d'Orgueil was confirmed, e.g., plaquettes, empilements de plaquette, and framboides.
TL;DR: The lesions obtained in vitro with some GBS sera, in the absence of mononuclear cells, have thus some similarities with those observed in the nerve fibres in vivo but the precise role of this serum factor in cases of this disease remains to be elucidated.
TL;DR: Mutations at the apf locus selectively depress the activity of a number of distinct amino acid permeases in Saccharomyces cerevisiae, but the uptake of pyrimidines and adenine is unaffected.
Abstract: Mutations at the apf locus selectively depress the activity of a number of distinct amino acid permeases in Saccharomyces cerevisiae. The activity of the general amino acid permease and specific amino acid permeases is decreased, but the uptake of pyrimidines and adenine is unaffected. Mutations at the apf locus are allelic to the aap mutation isolated by Surdin et al. Amino acid uptake is normal in a heterozygous diploid (apf/+) and in a tetraploid strain with only one functional allele at the apf locus.
TL;DR: A two-step synthesis of hexahelicene (scheme 1, 53% over-all yield), a three-and-a-half-stage synthesis of heptahelicenes (schemas 2, 3, and 4, 14% over all yield), and a two-and three-phase synthesis of Hexaheliene (Scheme 2, 33% overall yield) are described in this article.
Abstract: A two-step synthesis of hexahelicene (scheme 1; 53% over-all yield), a three-step synthesis of hexaheliene (scheme 2; 33% over-all yield), and a two-step synthesis of heptahelicene (scheme 3; 14% over-all yield) are described.
TL;DR: In vitro incubation of the mucosal specimens with tritiated thymidine and autoradiography was utilized to observed deoxyribonucleic acid-synthesizing cells and the height of the foveolae were estimated simultaneously in the same specimens.
TL;DR: The evoked potential correlates of sensory overload in forced-paced auditory tasks are examined and it is found that the cerebral “decision” potential can reveal intermittency in the perceptual channel.
Abstract: CEREBRAL evoked potentials can be monitored by averaging scalp records in subjects performing psychological tasks. The waveform is affected not only by the physical features of the sensory stimulus but also by cognitive and motivational parameters1–7. These can be manipulated through verbal instructions given to the subject and several studies have shown that a slow positive component of about 300 ms peak latency (P300) can be elicited by stimuli to which perceptual significance is attached2,5–8. We have examined the evoked potential correlates of sensory overload in forced-paced auditory tasks and find that the cerebral “decision” potential can reveal intermittency in the perceptual channel.