THE MAXIMUM-ENTROPY PRODUCTION PRINCIPLE IN CLIMATE MODELS - APPLICATION TO THE FAINT YOUNG SUN PARADOX

in Quarterly Journal Of The Royal Meteorological Society (1990), 116(495), 1123-1132

Current theories of stellar evolution imply that the solar luminosity was 25-30% less than at present during early phases of the Earth's history. The response of the global annual climate to changes of ... [more ▼]

Current theories of stellar evolution imply that the solar luminosity was 25-30% less than at present during early phases of the Earth's history. The response of the global annual climate to changes of the solar input is examined using the maximum entropy production (MEP) principle and a zonal energy balance model including ice-albedo feedback. It is shown that this formulation reproduces satisfactorily the present meridional heat flux and latitudinal temperature distributions. It is found that the model predicts that the efficiency of the meridional heat transport decreases for low values of the solar constant. Consequently, if the solar irradiance is lowered, a progressive development of the polar caps and a decrease of the global surface temperature are obtained without major irreversibility in the system. A comparison with a similar model including diffusive heat transport formalism shows that the value of the critical solar luminosity causing a global glaciation is decreased when the meridional heat fluxes are determined by the MEP principle. [less ▲]

Electronic and computer-aided astronomy: From eyes to electronic sensors -- I. S. McLean

in Ciel et Terre (1990), 106

Not Available

Projet d'un pont-canal en béton précontraint. Calcul et conception.

in Travaux (1990)

Bilan des paramètres climatiques et de pollution de l'air dans les locaux de maternité d'une porcherie d'élevage

in Annales de Médecine Vétérinaire (1990), 134(4), 243-248

Spontaneous production of anti-mouse red blood cell autoantibodies is independent of the polyclonal activation in NZB mice

in European Journal of Immunology (1990), 20

New Zealand Black (NZB) mice spontaneously develop an autoimmune hemolytic anemia together with a markedly increased production of polyclonal antibodies. The spontaneous generation of anti-mouse red blood ... [more ▼]

New Zealand Black (NZB) mice spontaneously develop an autoimmune hemolytic anemia together with a markedly increased production of polyclonal antibodies. The spontaneous generation of anti-mouse red blood cells (MRBC), anti-bromelain-treated MRBC (BrMRBC) and anti-DNA autoantibodies was compared to the polyclonal antibody formation in irradiated (800 rad) 2-month-old NZB mice reconstituted with bone marrow cells (BMC) from 2- or 10-month-old NZB mice. The injection of 10-month-old NZB BMC markedly accelerated the mortality rate in parallel with the progressive increase of anti-MRBC and anti-BrMRBC autoantibody production, but the spontaneous production of polyclonal IgM antibodies and anti-DNA autoantibodies was completely abolished down to the levels of non-autoimmune mice. In contrast, mice reconstituted with 2-month-old NZB BMC exhibited neither the acceleration of anemia nor the lack of polyclonal antibody production. These results strongly suggest that the spontaneous production of anti-MRBC autoantibodies, including anti-BrMRBC autoantibodies, in the NZB mouse occurs independently of the polyclonal B cell activation, and that they result from a specific immune stimulation, while the anti-DNA autoantibody production is a consequence of polyclonal antibody formation [less ▲]

Modélisation des échanges thermiques et de la circulation d'air dans un lit bactérien

in Revue des Sciences de l'Eau = Journal of Water Science (1990), 3(3), 303-324

The temperature is one of the main parameters governing the biological reactions in a trickling filter. The present model proposes a set of equations applicable for the determination of a temperature ... [more ▼]

The temperature is one of the main parameters governing the biological reactions in a trickling filter. The present model proposes a set of equations applicable for the determination of a temperature profile, and therefore of an average temperature, inside the trickling filter, when the flowrate and the temperature at entry of the liquid, the ambient air conditions (temperature and humidity) and the thermal exchange coefficients of the tower are known. Moreover, the airflow induced by natural draft is also computed when the head loss coefficients in the media and at entry are known. Beside this formulation, the first results of modal fitting on pilot plants are discussed. With few further developments, the method could be useful for the optimization of the operating temperature in a trickling filter which guarantees a sufficient airflow rate in the tower. [less ▲]

Mechanics of breathing during strenuous exercise in Thoroughbred horses

in Respiration Physiology (1990), 82(3), 279-294

The changes induced by exercise on the mechanics of breathing, as well as the simultaneous changes occurring in arterial blood gas tensions and in respiratory gas exchange were investigated in 6 healthy ... [more ▼]

The changes induced by exercise on the mechanics of breathing, as well as the simultaneous changes occurring in arterial blood gas tensions and in respiratory gas exchange were investigated in 6 healthy thoroughbred horses, performing a treadmill exercise of increasing intensity. Respiratory airflow and tidal volume (VT) were measured with ultrasonic flowmeters. Pleural pressure changes were measured by an oesophageal balloon catheter. Gas concentration of the expired air was analysed with a mass spectrometer; the oxygen consumption (VO2) and the carbon dioxide output (VCO2) were computed breath-by-breath. Arterial blood gas values were obtained by sampling from the carotid artery. Between rest and fast gallop VT, respiratory frequency, expired minute ventilation (VE), VO2, VCO2, total pulmonary resistance (RL), mechanical work of breathing (Wrm) and PaCO2 increased significantly while PaO2 decreased significantly. The Wrm.VO2(-1) ratio in galloping horses increased exponentially with VE. This, together with the relationship between the changes in PaO2 and in PaCO2 and the increase in the ventilatory mechanics parameters, suggests that the mechanics of breathing may be one of the factors constraining further increase in ventilation in exercising healthy horses. [less ▲]

A propos des dérivés gallo-romans de picus martius (Pline)

in Dialectes de Wallonie (1990), 18

Les fanes de pois constituent-elles un fourrage interessant pour le ruminant?

in Agricontact (1990), 219

Activation of human immunodeficiency virus type 1 by an oxidative stress

in AIDS Research and Human Retroviruses (1990)

Placental and pituitary growth hormone secretion during pregnancy in acromegalic women.

in Journal of Clinical Endocrinology and Metabolism (1990), 71(3), 725-31

It is now well established that during the second half of normal pregnancy, the human placenta secretes its specific GH variant (placental GH) in increasing amounts up to delivery. During the same period ... [more ▼]

It is now well established that during the second half of normal pregnancy, the human placenta secretes its specific GH variant (placental GH) in increasing amounts up to delivery. During the same period, pituitary GH secretion is progressively suppressed. The present study was aimed at clarifying the physiology of GH secretion in pregnant acromegalic women. Two young women remained acromegalic despite transphenoidal removal of their pituitary adenoma. Increased basal levels of GH and insulin-like growth factor-I (IGF-I) as well as paradoxical GH release after TRH injection were noted. Both women became pregnant and delivered term babies without any complication. In both patients, pituitary GH remained elevated during the entire pregnancy, contrary to the situation in normal women. Paradoxical GH release after TRH treatment was also present, whereas no response was observed in five normal control subjects. GH pulsatility studies revealed a highly pulsatile secretory pattern of pituitary GH, in contrast to that in normal woman, whose placental GH is secreted tonically. Tissue placental GH concentrations were within the range of levels in normal placentas. An increase in serum IGF-I in late pregnancy was also similar to that observed in normal pregnancy. These findings confirm that increased IGF-I levels are not pituitary GH dependent in late pregnancy. They add new evidence that adenomatous somatotrophs lack an IGF-I-dependent feedback regulation present in normal somatotrophs. [less ▲]

Renal biopsy and family studies in 65 children with isolated hematuria.

in Acta Paediatrica Scandinavica (1990), 79(6-7), 630-6

We have investigated 65 children with isolated hematuria persisting for at least a year. Renal biopsy specimens were studied by light microscopy, electron microscopy and immunofluorescence with antisera ... [more ▼]

We have investigated 65 children with isolated hematuria persisting for at least a year. Renal biopsy specimens were studied by light microscopy, electron microscopy and immunofluorescence with antisera specific against basement membrane components. The majority of the biopsies (62/65) showed variable histologic abnormalities. Four categories could be distinguished on combined histological and clinical criteria: Alport syndrome (n = 8), benign hematuria (n = 33, familial in 23), IgA nephropathy (n = 16) and increase in mesangial cells and matrix (n = 5). On the basis of our results, we suggest that a renal biopsy can establish diagnosis and prognosis in those children with isolated hematuria where the family history is negative. If the family has adult male individuals with isolated hematuria, a biopsy can usually be avoided, since this family history effectively excludes Alport syndrome. The use of antisera against basement membrane components did not allow a differentiation between Alport syndrome and benign hematuria. Goodpasture serum immunofluorescence was variable in the former and normally present in the latter. [less ▲]

Les déterminants de l'attitude face au choix vocationnel: Exploration par le Rorschach et le T.A.T.

in Bulletin de Psychologie (1990), 43(396), 773-784

MR1090950,Martinet, Jean ,Thermocińetique approfondie

in Mathematical Reviews [=MR] (1990)

Cultured neurons release an inhibitor of astroglia proliferation (astrostatine).

in Journal of Neuroscience Research (1990), 25(1), 58-70

Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation by neuronal cells. We demonstrate that medium conditioned by 7-day-old rat cerebellar granule neurons or ... [more ▼]

Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation by neuronal cells. We demonstrate that medium conditioned by 7-day-old rat cerebellar granule neurons or by 16-day-old rat embryo hippocampal neurons strongly inhibits the proliferation of cultured astroglial cells. Two neuronal cell lines, the PC12 rat pheocromocytoma and the neuro 2A (N2A) murine neuroblastoma also release such an activity. This release in N2A-conditioned medium (CM) occurs when the cells are at high density and show a low proliferation rate. This activity is present in media conditioned by neuronal cells, but not in media conditioned by normal astrocytes, by two glioma cell lines, or by one fibroblastic cell line. This proliferation inhibitor addresses normal astrocytes: the proliferation of two glioma cell lines, of a fibroblastic cell line, and of the two neuronal cell lines (PC12, N2A) is not inhibited by N2A CM. Moreover, this activity is directed against type 1 astrocytes, but not against type 2. Using three different assays, we demonstrate that DNA synthesis by astroglial cells is inhibited. N2A CM has no cytotoxic effect on astrocytes and does not modify their overall protein synthesis. Using affinity and gel filtration chromatography, we show that this activity is associated with a protein whose molecular weight ranges between 15 and 20 kDa. The possible relationship between this N2A cell-derived astroglia proliferation inhibitor and other types of potential glial proliferation inhibitors has been investigated. A brain glycoprotein immunologically related to epidermal growth factor receptor (EGFR) was reported to inhibit astroglial cell proliferation in vitro. Using polyclonal and monoclonal antibodies against EGFR, we were unable to immunoprecipitate the astrocyte proliferation inhibitor in N2A CM or to demonstrate by immunoblotting the presence of an EGFR-like immunoreactivity in the N2A CM or in the active chromatographic fractions of N2A CM. Transforming growth factor beta (TGF beta) is a well-known modulator of the proliferation of various cell types and was shown to be present in N2A CM. Using a polyclonal anti-TGF beta antibody that recognizes TGF beta on Western blots of N2A CM, we were unable to immunoprecipitate the astrocyte proliferation inhibitor of N2A CM. It seems thus far that the neuronal astroglia proliferation inhibitor is a new protein for which we propose the name astrostatine. [less ▲]

Clusters of galaxies -- W. V. Oegerle et al.

in Ciel et Terre (1990), 106

Not Available

Effet d'intervalle et estimation du risque systématique à la bourse de Bruxelles

in Journal de la Société de Statistique de Paris (1990), 131

LIPASES FROM PSYCHROTROPHIC ANTARCTIC BACTERIA

in FEMS Microbiology Letters (1990), 66(1-3), 239-243

Autoimmune syndrome after neonatal induction of tolerance to alloantigens: analysis of the role of donor T cells in the induction of autoimmunity

in Clinical & Experimental Immunology (1990), 79

The injection of (C57BL/6 x BALB/c) F1 spleen cells into BALB/c newborn mice leads to activation of persisting F1 donor B cells and development of a lupus-like syndrome in tolerized BALB/c mice. This ... [more ▼]

The injection of (C57BL/6 x BALB/c) F1 spleen cells into BALB/c newborn mice leads to activation of persisting F1 donor B cells and development of a lupus-like syndrome in tolerized BALB/c mice. This syndrome is characterized by hypergammaglobulinaemia, high levels of anti-DNA and anti-Sm antibodies, circulating immune complexes and deposits of immunoglobulin in renal glomeruli. The role of donor T cells in this model was investigated by injecting the newborn mice with F1 cells depleted in different T cell subsets by using specific monoclonal antibodies (MoAbs). Tolerance, as shown by an absence of H-2b-specific CTL alloreactivity and persistence of immunoglobulin bearing the donor allotype were observed in mice injected with F1 cells previously depleted in the CD4+ and/or CD8+ T cell subsets as well as in those which received Thy-1+-depleted F1 spleen cells. In these mice, a typical autoimmune syndrome was found, including splenomegaly and lymphadenopathy, anti-ssDNA and anti-aortic myosin IgG antibodies and renal deposition of immunoglobulin. However, some quantitative changes were seen: the levels of anti-aortic myosin antibodies were lower in mice tolerized with CD4+-depleted F1 cells than in those receiving untreated F1 cells. Conversely, higher levels of these autoantibodies were observed in mice tolerized with CD8+-depleted F1 cells. These results suggest that mature donor T cells are not necessary neither for the establishment of neonatal tolerance to alloantigens nor for the activation of F1 donor B cells in the production of the autoimmune syndrome in tolerant mice, but they may contribute in the regulation of the expression of autoreactive B cell clones. [less ▲]

Assessment of respiratory diseases and therapeutic intervention by the forced oscillation technique in feedlot cattle

in Research in Veterinary Science (1990), 49(3), 319-322

The forced oscillation technique was used to study pulmonary function in bulls during naturally acquired pulmonary-gastrointestinal disease complex known as shipping fever and as it was treated with two ... [more ▼]

The forced oscillation technique was used to study pulmonary function in bulls during naturally acquired pulmonary-gastrointestinal disease complex known as shipping fever and as it was treated with two different antibiotics. Fifteen double-muscled bulls of the Belgian White and Blue breed were investigated. Clinical, serological and pulmonary function values were recorded during and after naturally occurring respiratory disease. Total respiratory resistance (Rrs) and reactance (Xrs) were measured by the forced oscillation technique. The antibiotic ceftiofur (group A, n = 10) and oxytetracycline (group B, n = 5) were given over three days. A large increase of Rrs at low frequencies with a marked negative frequency dependence, an increase of the resonant frequency, and a decrease of Xrs were recorded in the initial stage of the disease. The parameters returned to normal values seven days later. Clinical evidence of recovery was more marked in group A than in group B. These results show that moderate shipping fever induces acute small and large airway obstruction which responds to appropriate antibiotic therapy. [less ▲]

Cloning and sequencing the upstream regulatory regions of the c-erbB2 gene.

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1990), 98(B40),

Treatment of endometriosis. Evaluation of preoperative therapy with danazol, gestrinone and buserelin (nasal spray and implant)

in Journal de Gynécologie, Obstétrique et Biologie de la Reproduction (1990), 19(6), 759-63

In order to adequately assess the effectiveness of danazol, gestrinone, buserelin-nasal spray (IN) and buserelin-implant (SC), a prospective non randomized study was initiated in 178 patients with ... [more ▼]

In order to adequately assess the effectiveness of danazol, gestrinone, buserelin-nasal spray (IN) and buserelin-implant (SC), a prospective non randomized study was initiated in 178 patients with laparoscopically confirmed ovarian endometriosis. After hormonal therapy, laparotomy with microsurgical resection of endometriotic cysts or laparoscopy laser was carried out. Regression (greater than 25%) of ovarian endometriosis was noted in 30, 34, 73 and 91% of cases after danazol, gestrinone and buserelin IN and buserelin SC respectively. Histological study proves that hormonal treatment leads to an incomplete suppression of ovarian endometriotic implants and this suggests the necessity to remove surgically invasive ovarian endometriosis. The pregnancy rate in moderate endometriosis (55%) differed significantly from the rate obtained in severe endometriosis (44%). The highest percentages were found after buserelin therapy. In conclusion, preoperative use of a potent GnRH agonist, administered subcutaneously, seems to be the best therapeutic approach when associated to surgery (CO2 laser or microsurgery). [less ▲]

L'école maternelle belge et la lecture

in Revue canadienne de l'étude en petite enfance (1990)

De la collecte à l'exploitation des données de productivité forestière : vers une approche intégrée

in Bulletin des Recherches Agronomiques de Gembloux (1990), 25(1), 103-113

Le syringomes à cellules claires

in Nouvelles Dermatologiques (1990), 9(8), 676

Clear cell syringoma us a rare disease, most often present in diabetic patients. The histological and immunohistochemical aspects of such lesion are reviewed.

Le recours répétitif à l'avortement en Grèce: comportement marginal ou étape du devenir-femme?

in Santé Publique et Sciences Sociales (1990), 8(3), 85-106

Neuro-imagerie fonctionnelle métabolique par émission de positons chez l'homme

in Revue Neurologique (1990), 146(8-9), 459-77

Positron emission tomography allows an in vivo assessment of various physiological and biochemical processes, for example cerebral blood flow, metabolism, or interactions between ligands and receptors ... [more ▼]

Positron emission tomography allows an in vivo assessment of various physiological and biochemical processes, for example cerebral blood flow, metabolism, or interactions between ligands and receptors. Data quantification and interpretation rest on models describing in a simple way the behavior of the labelled molecules. The general principles are common, but each model has limitations. The different methods are first validated in and applied to normal populations under resting conditions. New techniques for rapid assessments of blood flow and metabolism make it possible to measure cerebral activation after sensori-motor, mental or pharmacological stimulation. This should allow the study of recovery or plasticity of the lesioned brain, after a stroke for example. PET measurements of cerebral blood flow, oxygen consumption and extraction, and cerebral blood volume are particularly well suited to investigate the physiopathology of cerebrovascular diseases. Remote metabolic disturbances give information on interregional cerebral connections, and on clinico-metabolic correlations. In epilepsy, PET is useful in localizing the epileptogenic focus in partial epilepsy: it is hypometabolic interictally. The meaning of the hypometabolism has still to be established. New information about the neurochemistry of the epileptogenic focus should become available from studies of benzodiazepine, excitatory amino acid or opiate systems, for example. PET has already enabled pathophysiological hypotheses to be tested in status epilepticus. Disturbances of metabolism and neurotransmission systems have been observed at various stages and in various types of neurodegenerative diseases. The modifications are not only an early reflection of anatomopathological lesions, but could give more direct information on the pathogenesis or symptomatology of these diseases and hence lead to new therapeutic endeavours, such as appropriate replacement therapy analogous by to dopatherapy in Parkinson's disease. [less ▲]

Stereoselective effects of cocaine

in Behavioural Pharmacology (1990), 1

Nouveautés sur le pestivirus BVD/MD et sur l'infection asymptomatique qu'il provoque chez les bovins

in Annales de Médecine Vétérinaire (1990), 134

Practical Ephemeris Calculations -- Oliver Montenbruck

in Ciel et Terre (1990), 106

Not Available

Growth-Related Changes in the Pulmonary Function of Goats

in Veterinary Research Communications (1990), 14(2), 141-146

Growth-related changes in pulmonary function values were investigated in 20 healthy French Alpine goats, aged between 20 and 550 days, weighing 7-55 kg. Pulmonary ventilation, mechanics of breathing and ... [more ▼]

Growth-related changes in pulmonary function values were investigated in 20 healthy French Alpine goats, aged between 20 and 550 days, weighing 7-55 kg. Pulmonary ventilation, mechanics of breathing and arterial oxygen tension were measured using standardized techniques and methods adapted for goats of different body sizes. The Ppl values and the tI/tTOT ratio showed no significant changes with age and body size. The ventilation values (Vt, Ve, mVI and mVE) increased linearly with growth. There was a significant correlation of age and body weight with dynamic lung compliance (Cdyn), total pulmonary resistance (RL), viscous work of breathing (Wvis tot) and minute viscous work (Wvis min) throughout the age range studied. Cdyn, Wvis tot and Wvis min increased and RL decreased with age and body weight. Arterial blood gases (PaO2 and PaCO2) did not show significant changes over the age range studied. Regression equations for each pulmonary function parameter are given with body weight as the independent variable. Data for the mechanics of breathing were compared with those elsewhere for cattle, horses, man and dogs. [less ▲]

Reconstituted basement membrane matrix stimulates interstitial procollagenase synthesis by human fibroblasts in culture.

in Matrix (Stuttgart, Germany) (1990), 10(6), 373-7

Synthesis of interstitial collagenase by human fibroblasts was compared when cultured on plastic, in the presence or absence of soluble laminin, on a type I collagen gel and on a gel of basement membrane ... [more ▼]

Synthesis of interstitial collagenase by human fibroblasts was compared when cultured on plastic, in the presence or absence of soluble laminin, on a type I collagen gel and on a gel of basement membrane components (matrigel). Fibroblasts cultured on matrigel or on type I collagen gel displayed an increase in the steady-state levels of mRNA for interstitial procollagenase that was proportional to its enzymatic activity. Laminin, the main component of matrigel, had no effect on the interstitial collagenase synthesis by fibroblasts. We suggest that matrigel, which stimulates the interstitial collagenase production at a transcriptional step, could regulate the catabolic potential of fibroblasts. [less ▲]

Des hommes, des télescopes, des étoiles -- C. Fehrenbach

in Ciel et Terre (1990), 106

Not Available

Dans quelques années, pourra-t-on encore parler des tourbières hautes actives du plateau des Hautes-Fagnes?

in Documents de la Station scientifique des Hautes-Fagnes (1990), 15(3), 69-77

Evolution récente de la dégradation de la végétation de la partie centrale de la tourbière de la fagne Wallonne (Hautes-Fagnes). Résumé des travaux réalisés dans le cadre d'un mémoire de licence : cartes ... [more ▼]

Evolution récente de la dégradation de la végétation de la partie centrale de la tourbière de la fagne Wallonne (Hautes-Fagnes). Résumé des travaux réalisés dans le cadre d'un mémoire de licence : cartes de végétation, transects des espèces, analyses de la constitution de la tourbe, analyses palynologiques, analyses hydrologiques et propositions de quelques pistes de gestion de la tourbière pour enrayer les phénomènes de dégradation de la tourbière active. [less ▲]

Les modelés éoliens de la région de Zinder (Niger méridional): Etude de photo-géomorphologie. Note préliminaire. Apports de la télédétection à la lutte contre la sécheresse

in Actualité Scientifique Univ. Francophones (1990)

NO-CARRIER-ADDED (NCA) ARYL [F-18] FLUORIDES VIA THE NUCLEOPHILIC AROMATIC-SUBSTITUTION OF ELECTRON-RICH AROMATIC RINGS

in Journal of Fluorine Chemistry (1990), 48(2), 189-205

Nucleophilic aromatic substitution by [18F]fluoride ion has been demonstrated on rings containing electron donating groups in addition to the necessary electron withdrawing and leaving groups.

La pratique de la désinfection en élevage bovin

in Probio-Revue (1990)

Système immunitaire digestif et peptides neuroendocrines

in Revue Médicale de Liège (1990), XLV 7

Bovine leukemia : facts and hypotheses derived from the study of an infectious cancer

in Retroviruses biology and human disease, Dekker Press (1990)

Qualitative approach of the general vacuum Bianchi VI and VII cosmological models near the singularity

in General Relativity & Gravitation (1989), 21

We first show that the chaos-generating terms are absent from the vacuum field equations in the case of the general Bianchi VI and VII cosmological models. According to recent studies, this proves that ... [more ▼]

We first show that the chaos-generating terms are absent from the vacuum field equations in the case of the general Bianchi VI and VII cosmological models. According to recent studies, this proves that the Kasnerian metric is a general solution for these models in the neighborhood of the initial singularity. Then, using a method developed by Jantzen, we reduce the field equations to a nonautonomous system of order two. A numerical integration leads to the explicit four-parameter asymptotic form of a general solution, which is indeed Kasnerian in the canonical invariant basis. [less ▲]

Nucleotide Sequence of the Gene Encoding the Active-Site Serine Beta-Lactamase from Actinomadura R39

in FEMS Microbiology Letters (1989), 65(3), 241-246

The gene encoding the extracellular, active-site serine beta-lactamase of Actinomadura R39, previously cloned into Streptomyces lividans, has the information for the synthesis of a 304 amino acid protein ... [more ▼]

The gene encoding the extracellular, active-site serine beta-lactamase of Actinomadura R39, previously cloned into Streptomyces lividans, has the information for the synthesis of a 304 amino acid protein, the amino terminal region of which has the characteristic features of a signal peptide. The Actinomadura R39 beta-lactamase is another member of the class A beta-lactamases. In particular, it shows high homology with the beta-lactamase of Bacillus licheniformis. [less ▲]

Sous le Swing de la Croix

in Prologue (1989), (224), 28-29

Epilepsy: The Use of Oxygen-15-Labeled Gases

in Seminars in Neurology (1989), 9(4), 307-16

Une alimentation correcte pour preparer les genisses a leur carriere de hautes productrices.

in Elevages Belges (1989), 42(12), 24-27

Correlation between the Sexually Dimorphic Aromatase of the Preoptic Area and Sexual Behavior in Quail: Effects of Neonatal Manipulations of the Hormonal Milieu

in Archives Internationales de Physiologie et de Biochimie (1989), 97(6), 465-81

The aromatase of the preoptic area is significantly more active in males than in females. This sex dimorphism in enzyme activity is still found in birds that have been gonadectomized and treated with a ... [more ▼]

The aromatase of the preoptic area is significantly more active in males than in females. This sex dimorphism in enzyme activity is still found in birds that have been gonadectomized and treated with a same dose of testosterone. This suggests that the sex difference is not the result of a differential activation by the adult hormonal environment but rather is organized neonatally by steroid hormones. As the central aromatization of testosterone is a limiting step in the activation of copulatory behavior by testosterone, the lower aromatase activity in the preoptic area of females might be responsible, at least in part, for their lower sensitivity to the activating effects of testosterone on behavior. Three experiments were carried out to determine whether early manipulations of the hormonal environment, which are known to differentiate sexual behavior, also affect in a permanent way the aromatase activity in the preoptic area. Injection of estradiol benzoate into male embryos on day 9 of incubation decreased the preoptic aromatase activity in parallel to its demasculinizing effect on behavior. Unexpectedly the same treatment tended to increase enzyme activity in females so that the physiological relevance of the observed enzymatic change remains questionable. In two independent experiments, we confirmed that neonatal ovariectomy of female quail interferes with their behavioral differentiation. Females gonadectomized at 4 days post-hatch showed significantly more male-type sexual behavior as adult in response to testosterone than females gonadectomized at the age of 5 weeks. These experiments also confirmed that the preoptic aromatase activity is higher in males than in females but no evidence for an effect of the age of gonadectomy on the enzyme activity could be obtained. The sex difference and experimental modifications observed in the aromatase activity of the preoptic area were not seen in the posterior hypothalamus demonstrating that these effects are specific. The mechanisms controlling the sex difference in aromatase activity are discussed. The difference might be organized by the action of embryonic steroids as suggested by the changes observed in males injected with estradiol benzoate in egg. Alternatively, activational mechanisms cannot be ruled out at present. In one experiment, the activity of the preoptic aromatase was positively correlated with the sexual activity of the birds.(ABSTRACT TRUNCATED AT 400 WORDS) [less ▲]

Cultured Astroglia Release a Neuronotoxic Activity That Is Not Related to the Excitotoxins

in Brain Research (1989), 502(1), 21-7

Neuronal death after brain injury is thought to be in part the result of the activity of the excitotoxins, a family of excitatory amino acids which are released by neurones. We have also described an ... [more ▼]

Neuronal death after brain injury is thought to be in part the result of the activity of the excitotoxins, a family of excitatory amino acids which are released by neurones. We have also described an astroglial cell-derived neuronotoxic activity of low molecular weight whose release can be induced by depolarizing events such as an increase in extracellular potassium concentration. We study here the relationship between this astroglia-derived neuronotoxic activity present in astroglia-conditioned medium (ACM) and the excitotoxins. Using a colorimetric assay of neuronal survival, we show that the ACM neuronotoxic activity, is able to induce the death of all types of neurones tested, including those which are insensitive to excitotoxins. Furthermore, the ACM neuronotoxic activity does not require for its action the extracellular ionic composition which is needed for the activity of excitotoxins. Finally, the ACM neuronotoxic activity is not blocked by competitive or non-competitive antagonists of the various classes of excitotoxin receptors. Those data demonstrate that the astroglia-derived neuronotoxic activity is not related to the excitotoxins. Still, because astrocytes can also be depolarized by members of the excitotoxin family, the possibility exists that the release of astroglia-derived neuronotoxic activity would follow the rise in extracellular excitatory amino acid concentration during nervous system injury. [less ▲]

Infrared photometry and spectrophotometry of SN 1987A. I - March to October 1987 observations

in Astronomy and Astrophysics. Supplement Series (1989), 80

IR (1-20 micron) observations, photometry, and narrow band spectrophotometry of SN 1987A obtained between March 16 and October 12, 1987, are presented. Variations of the bolometric luminosity are ... [more ▼]

IR (1-20 micron) observations, photometry, and narrow band spectrophotometry of SN 1987A obtained between March 16 and October 12, 1987, are presented. Variations of the bolometric luminosity are determined from IR and optical photometry. The spectral energy distribution, effective radius, and effective temperature of the hotter component are derived. Also, observations of hydrogen lines and CO emission are discussed. [less ▲]

Further Studies on the Mechanism of Radiation Induced Thymic Lymphoma Prevention by Bone Marrow Transplantation in C57bl Mice

in Leukemia : Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K (1989), 3(11), 813-8

Whole body fractionated irradiation induces thymic lymphomas in C57BL/Ka mice after a latent period during which intrathymic lymphopoiesis is modified; thymocyte numbers are subnormal and the epithelial ... [more ▼]

Whole body fractionated irradiation induces thymic lymphomas in C57BL/Ka mice after a latent period during which intrathymic lymphopoiesis is modified; thymocyte numbers are subnormal and the epithelial component of thymic nurse cells (TNCs) is altered as estimated by the number of TNCs in vivo and by its ability to interact with immature thymocytes in vitro. A graft of normal bone marrow cells immediately after the last irradiation prevents the development of lymphomas; but when such a graft is performed 1 month later, it does not inhibit the emergence of tumors. In both cases the grafted precursors home and repopulate the thymus. However, the delayed graft does not exert any effect upon the altered epithelial component of TNCs, whereas the early one restores the numbers of TNCs and the function of their epithelial component. The results thus demonstrate that lymphoid thymic repopulation by a bone marrow graft is not sufficient to prevent the development of lymphomas and that there is an intimate relationship between tumor development and alterations of nurse cells microenvironment. [less ▲]

The Triplet States of AlCl

in Journal of Molecular Spectroscopy (1989), 138(1), 264-271

The 0-0 band of the a3Πr-X1Σ+ transition has been fully analyzed. The b3Σ state observed by Sharma (Astrophys. J. 113, 210–218 (1951)) is shown to be a 3Δ state and the analysis of the 0-0, 0–1, and 0–2 ... [more ▼]

The 0-0 band of the a3Πr-X1Σ+ transition has been fully analyzed. The b3Σ state observed by Sharma (Astrophys. J. 113, 210–218 (1951)) is shown to be a 3Δ state and the analysis of the 0-0, 0–1, and 0–2 bands of the b3Δ-a3Πr transition has been completed. [less ▲]

Jean-Paul Dubois, Edgar P. Jacobs. La Marque jaune

in Textyles : Revue des Lettres Belges de Langue Française (1989), 6