Showing papers by "Université libre de Bruxelles published in 1975"
TL;DR: Evidence for the presence in the vertebrate nervous system of a hitherto undescribed brain gastrin immunoassayable peptide (BGP) is presented here.
Abstract: RELEASING factors1 and other brain peptides2 have been the subject of extensive studies and the high sensitivity of modern measurement techniques has led to the discovery, in various tissues3,4 and in the nervous system5–9, of new, unpredicted locations for otherwise well known peptides. Evidence for the presence in the vertebrate nervous system of a hitherto undescribed brain gastrin immunoassayable peptide (BGP) is presented here.
723 citations
TL;DR: The SOS repair hypothesis has already served as the working hypothesis for many experiments, and some speculations are presented to stimulate further discussions and experimental tests.
Abstract: A hypothesis was proposed several years ago that Escherichia coli possesses an inducible DNA repair system (“SOS repair”) which is also responsible for induced mutagenesis. Some characteristics of the SOS repair are (1) it is induced or activated following damage to DNA, (2) it requires de novo protein synthesis, (3) it requires several genetic functions of which the best-studied are recA + and lex + of E. coli, and (4) the physiological and genetic requirements for the expression of SOS repair are suspiciously similar to those necessary for the prophage induction. The SOS repair hypothesis has already served as the working hypothesis for many experiments, some of which are briefly reviewed. Also, some speculations are presented to stimulate further discussions and experimental tests.
656 citations
TL;DR: The self-diffusion coefficient of n-butane is approximately 6.0 × 10−5 cm2/s and the corresponding velocity autocorrelation function displays practically no cage effect, differing markedly from argon and other simple fluids.
578 citations
TL;DR: In this article, the role of long wave length hydrodynamical processes in the analysis of time-dependent correlation functions is discussed and various tools and methods which are used to describe these processes are discussed.
375 citations
TL;DR: In this article, the numerical stability of simple marching schemes used in elasto/visco-plasticity is investigated and a theoretical stability criterion based on the identification of the numerical process with the integration of a nonlinear, first order, system of ordinary differential equations is derived.
Abstract: The numerical stability of simple marching schemes used in elasto/visco‐plasticity is investigated. An assumption of convexity renders possible the derivation of a theoretical stability criterion based on the identification of the numerical process with the integration of a non‐linear, first order, system of ordinary differential equations. Explicit stability criteria are obtained for commonly used visco‐plastic laws. Selected examples illustrate the necessity and effectiveness of the proposed stability criteria in actual computations. Copyright © 1975 John Wiley & Sons, Ltd
270 citations
TL;DR: In this article, a model nonlinear network involving chemical reactions and diffusion is studied and the time evolution and bounds on the steady state solutions of the dissipative structure type are found by bifurcation theory.
163 citations
TL;DR: Single electrical stimuli to the gums and mucosa inside the mouth elicit two successive exteroceptive suppressions in the voluntary electromyogram of the masseter and temporalis muscles in normal man.
161 citations
TL;DR: In patients of group C with a locked-in syndrome, the cerebral evoked potentials presented marked bilateral anomalies which provided interesting data about the extension of the pontine vascular lesions into the tegmentum, which contributed to the slowing of corticipetal conduction.
Abstract: Clinical and electrophysiological observations are described in 7 patients with clinically well-identified vascular lesions of the brain-stem or diencephalon. In the patients of Group A with a thalamic syndrome, the somatosensory cerebral evoked potentials had a reduced voltage and increased latency on the affected side. No significant anomalies were recorded in the patients of Group B with a Wallenberg or Weber syndrome. In patients of group C with a locked-in syndrome, the cerebral evoked potentials presented marked bilateral anomalies which provided interesting data about the extension of the pontine vascular lesions into the tegmentum. The pathophysiological mechanisms involved in the changes of average cerebral evoked potentials and in the slowing of corticipetal conduction are discussed.
145 citations
TL;DR: The data suggest a model in which an intracellular agent resulting from the oxidation of iodide acts on the thyroid cyclic AMP system, which is also observed in horse, beef and sheep thyroid slices and in rats stimulated by parathyroid hormone.
Abstract: The action of iodide on the cyclic AMP system of dog thryoid slices has been studied. Iodide inhibits the enhancement of cyclic AMP accumulation in the presence of TSH. Such an effect is also observed in horse, beef and sheep thyroid slices, but not in dog kidney slices stimulated by parathyroid hormone or in rat parotid slices stimulated by isoproterenol. The effect in dog thyroid slices is suppressed by iniM NaClO4, lm M methimazole and lmM propylthiouracil. Similar data have been obtained for prostaglandin Ei stimulation. Effects of thyrotropin mediated by cyclic AMP, i.e., activation of iodothyronine secretion, l-14C-glucose oxidation, and lactate formation, were also inhibited by iodide but not by iodide and methimazole. Similar activations when caused by dbcAMP were not inhibited by iodide. The data suggest a. model in which an intracellular agent resulting from the oxidation of iodide acts on the thyroid cyclic AMP system. (Endocrinology 96: 781, 1975)
120 citations
TL;DR: In this paper, the surface charge of monodisperse polystyrene chains has been investigated using potentiometric and conductometric titrations, and strong acidic groups were detected for latices prepared in the presence of strong acid soaps.
112 citations
TL;DR: In this article, the rate constants of radiationless S1 → Tn and T1 → S0 intersystem crossing of six helicenes have been evaluated by combining emission lifetimes and quantum yields of fluorescence and triplet state formation.
TL;DR: In this paper, the authors investigated the nitrification and repartition of nitrifying bacteria in the auto-epuration zone of the Scheldt estuary and found that most of the nitrate and nitrite production occurs in the water of the river itself.
TL;DR: In this paper, the steady state spatial patterns arising in nonlinear reaction-diffusion systems beyond an instability point of the thermodynamic branch are studied on a simple model network, and a detailed comparison between the analytical solutions of the kinetic equations, obtained by bifurcation theory, and the results of computer simulations is presented for different boundary conditions.
TL;DR: In this paper, the effects of carbamylcholine, NaF, KCl and calcium in the presence of ionophore A23187 enhanced cyclic GMP accumulation and activated the oxidation of glucose carbon 1 and the binding of iodide to proteins in thyroid slices.
TL;DR: In this article, a theory of fluctuations of macrovariables in nonequilibrium systems based on a nonlinear master equation is outlined, which takes into account, via a "mean field" type of approximation, the effect of the spatial extension of fluctuations.
Abstract: A theory of fluctuations of macrovariables in nonequilibrium systems based on a nonlinear master equation is outlined. This equation takes into account, via a “mean field” type of approximation, the effect of the spatial extension of fluctuations. A comparison with the birth and death formalism reveals several unsatisfactory features of the latter.
TL;DR: The authors present the case of a child aged 7 years who suffered from relapsing acute lymphocytic leukemia, who died after a period of seizures and unconsciousness and the main pathologic data obtained consisted of calcifications located bilaterally in the cerebral and cerebellar cortex.
Abstract: The authors present the case of a child aged 7 years who suffered from relapsing acute lymphocytic leukemia. Treatment consisting mainly of oral and intrathecal methotrexate and x-ray therapy produced remission of the hematologic symptoms. Three years after the onset of the leukemia, mental deterioration gradually appeared. Radiography of the skull revealed diffuse bilateral calcium deposits in both cerebral and cerebellar hemispheres. Four years after the onset of the disease, a hematologic relapse occurred. Behavioral disorders became more severe and the child died after a period of seizures and unconsciousness. The main pathologic data obtained by the study of a brain biopsy and after a complete postmortem examination consisted of calcifications located bilaterally in the cerebral and cerebellar cortex. No signs of leukemia were present. Cerebral calcification is an extremely rare complication in the course of the therapy of lymphocytic leukemia. Its possible causes are discussed.
TL;DR: It is concluded that cyclic AMP is probably the intracellular messenger of both secretin and VIP in centroacinar cells.
TL;DR: The simultaneous production of AFP and a hepatocyte specific marker (albumin) by cloned hepatoma cells show that the production ofAFP by the tumours is due to the tumoural hepatocytes themselves.
TL;DR: In this paper, photo-induced double cyclodehydrogenation of bis-arylvinyl arenes was used to synthesize a helicene in one operational step by photoinduced doublecyclodehydrogens.
TL;DR: The onset of a morphogenetic gradient and pattern formation are combined in a single coherent model and size invariance and its biological implications are discussed.
TL;DR: Ethinylestradiol (400 pg/day) does not only stimulate prolactin release in normal cycling women but also modifies the pattern of the circadian periodicity of circulating Prolactin: the nocurnal rise is of reduced amplitude but covers a larger part of the nyctohemeral period as compared to the situation during a control period in the same subjects.
Abstract: Ethinylestradiol (400 µg/day) does not only stimulate prolactin release in normal cycling women but also modifies the pattern of the circadian periodicity of circulating prolactin: the nocturnal rise is of reduced amplitude but covers a larger part of the nyctohemeral period as compared to the situation during a control period in the same subjects. The values start rising long before sleep, i.e., at 2 PM, under estrogen treatment and during sleep, i.e., at 4 AM, during the control period. In both cases, however, the values remain high until 8 AM and are minimal at 12 AM. (J Clin Endocrinol Metab 40: 886, 1975)
TL;DR: The structure elucidation of myrrhine (6), a novel base isolated from Myrrha 18- guttata, is reported in this article, where the biogenesis of the Coccinellidae defensive alkaloids is discussed and coccinelline is shown to be biosynthetized through the polyacetate pathway.
TL;DR: Computerized molecular model building has been used to deduce the arrangement of sickle cell hemoglobin molecules (Hb-S) in the tubular fibers and a "best" solution has been found which satisfies all of the reported properties of these fibers.
Abstract: Computerized molecular model building has been used to deduce the arrangement of sickle cell hemoglobin molecules (Hb-S) in the tubular fibers which form within sickling cells and in concentrated cell-free solutions of deoxygenated Hb-S. A "best" solution has been found which satisfies all of the reported properties of these fibers. In the proposed arrangement the contact between adjacent Hb-S molecules in the direction parallel to the fiber axis is primarily hydrophobic and in addition contains two salt bridges between the molecules. This contact would be disrupted with the Glu of Hb-A at the beta6 position instead of the Val of Hb-S, and it would not make a long fiber with oxygenated Hb-S. Residues in the A helix and the GH corner of the beta2 chain of one molecule are in contact with residues of the A, B, and E helices and the GH corner of the alpha1 chain of its neighbor. The intermolecular contact in the direction perpendicular to the fiber axis is mainly between the end of the E helix and the EF corner of the beta1 chain on the first molecule and the F helix and FG corner of the alpha2 chain of its neighbor. Some of the implications of these contacts are reported here, and others will be presented in subsequent papers.
TL;DR: Sinulariolide, a novel diterpene lactone has been isolated from the alcyonarian Sinularia flexibilis as mentioned in this paper, and its structure has been determined by using spectroscopic and chemical methods.
TL;DR: A mutant of Escherichia coli strain K12S isolated after selection for resistance to the amino glycoside antibiotic neamine shows severe restriction of amber suppressors in vivo as discussed by the authors.
TL;DR: Using scanning electron microscopy, this work state a more precise picture of the frontal weapon, which consists ofThe frontal gland, the pore and its associated cephalic structures involved in the defensive system of the insect.
Abstract: La glande frontale des termites est une glande tegumentaire impaire. Chez les soldats de Rhinotermitidae, elle forme une profonde invagination qui s'ouvre a l'avant de la tete par le pore frontal ou fontanelle. Cette glande est bien developpee et s'etend generalement jusqu'a l'arriere du corps de l'insecte.
TL;DR: It is shown that after experimental myotomy in the baboon biceps muscle, the nerve-free segments develop fibrillation after a consistent delay and that by comparing different clinical types of human myopathies a correlation can be found between the incidence of focal necrosis and spontaneous fibrillations.
Abstract: DENERVATED skeletal muscle fibres have long been known to show spontaneous fibrillation potentials, this being one of the features resulting from the removal of the trophic influence of the motor nerve1. Electromyography (EMG) has shown spontaneous fibrillations in human myopathies such as myositis or muscular dystrophy2–6, but their true incidence and mechanism is still obscure. We propose that myopathic fibrillations result from segmental necrosis of muscle fibres so that a distal fibre segment is separated from the part carrying the motor endplate. We show here, first, that after experimental myotomy in the baboon biceps muscle, the nerve-free segments develop fibrillation after a consistent delay and second, that by comparing different clinical types of human myopathies a correlation can be found between the incidence of focal necrosis and spontaneous fibrillation potentials. Our findings are consistent with our previous report of collateral innervation of newly formed nuscle fibres in Duchenne muscular dystrophy7.
TL;DR: This model fits better the experimental data obtained in 20 young normal adults than the currently used exponential model of Salazar and Knowles (1964), and the independence between the constant K' and body height is interpreted as a constancy of pulmonary structure for normal subjects of the same age range.
TL;DR: The thermal cracking of phenol 1-14 C and tritiated in specific positions has been studied at atmospheric pressure between 665 and 865°C with a contact time of 2·5 seconds, suggesting the most probable reactions occuring during the thermal cracking.
TL;DR: The SV40 DNA-RNA polymerase complex described here has an endogenous transcriptional activity, which is highly sensitive to cy-amanitin, a specific inhibitor of nucleoplasmic polymerase B or II [ 111; this should prove of great interest in the study of the regulation of viral gene expression.