References of "1975"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailubvy photometry of some southern field stars.
Heck, A.; Manfroid, Jean ULg

in Astronomy and Astrophysics. Supplement Series (1975), 22

Abstract image available at: http://cdsads.u-strasbg.fr/abs/1975A&AS...22..323H

Detailed reference viewed: 11 (2 ULg)
Peer Reviewed
See detailDegradation of benzylpenicillin by the exocellular DD-carboxypeptidase-transpeptidase from Streptomyces R 61
Frère, Jean-Marie ULg; Adriaens, P.; Degelaen, J. et al

in Archives Internationales de Physiologie et de Biochimie (1975), 83(5), 905-907

Detailed reference viewed: 12 (0 ULg)
Peer Reviewed
See detailVariability of the effects of serum-free medium, dibutyryl-cyclic AMP or theophylline on the morphology of cultured new-born rat astroblasts.
Moonen, Gustave ULg; Cam, Y.; Sensenbrenner, M. et al

in Cell & Tissue Research (1975), 163(3), 365-372

Detailed reference viewed: 3 (0 ULg)
Peer Reviewed
See detailInactivation of rat liver RNA polymerases I and II and yeast RNA polymerase I by pyrodixal 5'-phosphate. Evidence for the participation of lysyl residues at the active site.
Martial, Joseph ULg; Zaldivar, J.; Bull, P. et al

in Biochemistry (1975), 14

Purified DNA-dependent RNA polymerase forms I (A) and II (B) from rat liver and form I from yeast are rapidly inactivated by pyridoxal 5'-phosphate at pH 8.0. The inhibition is relatively specific since ... [more ▼]

Purified DNA-dependent RNA polymerase forms I (A) and II (B) from rat liver and form I from yeast are rapidly inactivated by pyridoxal 5'-phosphate at pH 8.0. The inhibition is relatively specific since pyridoxamine 5'-phosphate is not an inhibitor and pyridoxal is about 12 times less effective than pyridoxal 5'-phosphate. The inactivation is reversed by high concentrations of amines, and can be made irreversible by reduction with NaBH4. Spectral analysis of the inhibited enzyme and its NaBH4 reduction product indicates that a Schiff base forms between the aldehyde group of pyridoxal 5'-phosphate and one or more amino groups of the protein. Nepsilon-Pyridoxyllysine was identified as the only product in acid hydrolysates of the reduced yeast RNA polymerase I-pyridoxal 5'-phosphate complex. Complete inactivation of yeast polymerase I results in the incorporation of 3-4 mol of pyridoxal 5'-phosphate/1 mol of enzyme. DNA and nucleotide substrates partially protect the enzymes from inactivation. These results suggest that one or more lysyl amino groups are critical for the activity of animal RNA polymerases and show that pyridoxal 5'-phosphate is a suitable probe for studying the active sites of these enzymes. Comparison of the present results with those previously obtained with Eschericha coli RNA polymerase in this laboratory suggest a new degree of structural homology between eucaryotic and procaryotic RNA polymerases. [less ▲]

Detailed reference viewed: 9 (0 ULg)
See detailHet Nederlandse lied door de eeuwen heen
Vromans, Joseph ULg

Conference given outside the academic context (1975)

Detailed reference viewed: 21 (0 ULg)
Full Text
Peer Reviewed
See detailVariation du 17 ß oestradiol au cours du cycle oestral chez la vache
Ectors, Francis ULg; Beckers, Jean-François ULg; Ballman, Patricia et al

in Comptes Rendus de l'Académie des Sciences de Paris (1975), 281

Le dosage du 17 beta oestradiol plasmatique, sans recours préalable à la chromatographie de partage, a pu être réalisé et ce en raison de la haute spécificité de l'antisérum utilisé. Le 17 beta oestradiol ... [more ▼]

Le dosage du 17 beta oestradiol plasmatique, sans recours préalable à la chromatographie de partage, a pu être réalisé et ce en raison de la haute spécificité de l'antisérum utilisé. Le 17 beta oestradiol augmente à partir du 18e jour du cycle jusqu'à atteindre 8,6 pg/ml (6,4 à 12,6 pg/ml) au début de l'oestrus. Outre ce pic oestral, 3 pics accessoires peuvent être détectés: le premier, pratiquement constant, se situe entre le 4e et le 5e jour, le second moins important et seulement retrouvé chez 75% des sujets survient entre le 12e et le 14e jour. Enfin, le troisième, très inconstant, se retrouve parfois au 8e jour. Le taux basal moyen chez la vache est de 1,75 pg/ml. [less ▲]

Detailed reference viewed: 404 (3 ULg)
Full Text
See detailProblèmes de l'Université et réforme des structures universitaires
Welsch, Maurice ULg

Speech/Talk (1975)

Detailed reference viewed: 10 (1 ULg)
See detailInterview: Billy Boy Arnold
Sacré, Robert ULg

Article for general public (1975)

Detailed reference viewed: 18 (0 ULg)
See detailBILLY BOY ARNOLD Portrait
Sacré, Robert ULg

Article for general public (1975)

Detailed reference viewed: 18 (0 ULg)
Full Text
Peer Reviewed
See detailPrésence de HF dans la stratosphere supérieure
Zander, Rodolphe ULg

in Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Séries A et B, Sciences Physiques (1975), 281(12), 213-214

Solar observations performed with a stratospheric gondola at 27.5 km altitude have allowed recording the solar spectrum near 2.5 μ, with a resolution of 0.04 cm-1. An absorption line observed at 4038.97 ... [more ▼]

Solar observations performed with a stratospheric gondola at 27.5 km altitude have allowed recording the solar spectrum near 2.5 μ, with a resolution of 0.04 cm-1. An absorption line observed at 4038.97 cm-1 has been attributed to HF, a species which would be present in the upper stratosphere. [less ▲]

Detailed reference viewed: 19 (4 ULg)
Full Text
Peer Reviewed
See detailInteraction between the exocellular DD-carboxypeptidase-transpeptidase from Streptomyces R61, substrate and beta-lactam antibiotics. A choice of models
Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg; Perkins, Harold R

in European Journal of Biochemistry (1975), 57(2), 353-359

The interaction between the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61 and beta-lactam antibiotics is a multistep process during which a rather stable enzyme - antibiotic complex ... [more ▼]

The interaction between the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61 and beta-lactam antibiotics is a multistep process during which a rather stable enzyme - antibiotic complex is formed. This mechanism of interaction is compatible with Lineweaver-Burk plots that are typical of a competitive inhibition of the hydrolysis of the peptide donor by the antibiotic. In fact, however, the same Lineweaver-Burk plots can be obtained on the basis of a non-competitive type of inhibition. At present, a choice between the two models cannot be made. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailKinetics of interaction between the exocellular DD-carboxypeptidase-transpeptidase from Streptomyces R61 and beta-lactam antibiotics. A choice of models
Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg; Iwatsubo, Motohiro

in European Journal of Biochemistry (1975), 57(2), 343-351

The simplest model for the interaction between the exocellular DD-carboxypeptidase-transpeptidase from Streptomyces R61 and beta-lactam antibiotics involves the three following steps: (a) the formation of ... [more ▼]

The simplest model for the interaction between the exocellular DD-carboxypeptidase-transpeptidase from Streptomyces R61 and beta-lactam antibiotics involves the three following steps: (a) the formation of a reversible equimolar enzyme - antibiotic complex; (b) the irreversible transformation of this complex into a modified enzyme - antibiotic complex; and (c) the breakdown of this latter complex and the concomitant release of a regenerated enzyme and a modified antibiotic molecule. The dissociation constant for step 1 and the rate constants for steps 2 and 3 were measured with various beta-lactam antibiotics. With antibiotic such as benzylpenicillin, which behaves as a good 'substrate', steps 1 and 2 occur at enzymic velocities, whereas step 3 occurs at a very low velocity and hence is responsible for the low efficiency of the overall process. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailForbidden lines in a newly formed H II region
Manfroid, Jean ULg

in Astronomy and Astrophysics (1975), 43

The initial evolution of a spherically symmetric H II region forming around a star of 36 solar masses is calculated numerically using a program based on a finite-difference scheme extrapolated from those ... [more ▼]

The initial evolution of a spherically symmetric H II region forming around a star of 36 solar masses is calculated numerically using a program based on a finite-difference scheme extrapolated from those previously proposed for solving hydrodynamic problems involving shock waves. The helium abundance is assumed to be 10 per cent, and no account is taken of magnetic fields, turbulent motions, or interstellar grains. The evolution of the positions of the hydrogen and helium ionization fronts is plotted as a function of time, and the total spectra of the forbidden emission lines of C II, N II, N III, O II, O III, Ne II, and Ne III are computed at each time. The intensities of the 29 strongest lines at five different epochs are compared with a rough estimate of the total strength of H-beta. The temporal evolution of the nebula and the emission lines is described qualitatively. [less ▲]

Detailed reference viewed: 23 (1 ULg)
Peer Reviewed
See detailPlatelet size in man
Paulus, Jean-Michel ULg

in Blood (1975), 46(3), 321-336

The large heterogeneity in platelet volumes is caused mainly by the aleatory variations in territory growth and demarcation inside megakaryocyte cytoplasm, rather than by aging in circulation.

Detailed reference viewed: 12 (1 ULg)
Full Text
Peer Reviewed
See detailThe catalytic activity and penicillin sensitivity in the liquid and frozen states of membrane-bound and detergent-solubilised transpeptidase of Streptomyces R61
Dusart, Jean; Marquet, Alberto; Ghuysen, Jean-Marie ULg et al

in European Journal of Biochemistry (1975), 56(1), 57-65

The Km, app. values of the membrane-bound transpeptidase of Streptomyces R61 for the donor Ac2-L-Lys-D-Ala-D-Ala and the acceptor Gly-Gly are not affected by temperature variations when the reaction ... [more ▼]

The Km, app. values of the membrane-bound transpeptidase of Streptomyces R61 for the donor Ac2-L-Lys-D-Ala-D-Ala and the acceptor Gly-Gly are not affected by temperature variations when the reaction mixtures are incubated in liquid suspensions. At -5 degrees C, the incubation can be carried out either in the liquid or in the frozen state. The enzyme is active in the latter state. In the frozen state, the Km, app. value for the acceptor remains unchanged but there is a 3-fold increase in the maximum velocity, a 10-fold decrease of the Km, app. value for the donor and a 10-fold increase of the benzylpenicillin concentration required to inhibit the enzyme activity by 50% (ID50 value). Temperatures of -35 degrees C or below are required to completely inhibit the membrane-bound enzyme in the frozen state. Cetyltrimethylammonium bromide extracts the transpeptidase both from the isolated membranes and, with a much higher yield, from the intact mycelium. The extracted enzyme is not active in the frozen state, requires detergent for activity, has decreased Km, app. values for both donor and acceptor, exhibits the same sensitivity to benzylpenicillin and cephalosporin C as the membrane-bound transpeptidase (in liquid suspensions) and, like this latter enzyme, has no DD-carboxypeptidase activity. The detergent-extracted transpeptidase penetrates gels of Sephadex-100 and is not sedimented at 200 000 X g. [less ▲]

Detailed reference viewed: 10 (1 ULg)
Peer Reviewed
See detailEffects of synthetic tripeptide on the differentiation of dissociated cerebral hemisphere nerve cells in culture.
Sensenbrenner, M.; Jaros, G. G.; Moonen, Gustave ULg et al

in Neurobiology (1975), 5(4), 207-213

Detailed reference viewed: 3 (0 ULg)
Full Text
See detailAn empirical study of the industrial marketing mix
Choffray, Jean-Marie ULg

E-print/Working paper (1975)

In this paper, we relate the gross contribution of industrial products to the spending rate for personnal selling, technical service, and advertising activities. Our empirical study provides some ... [more ▼]

In this paper, we relate the gross contribution of industrial products to the spending rate for personnal selling, technical service, and advertising activities. Our empirical study provides some indications about how industrial marketing activities might work, and gives tentative answers to some important questions faced by industrial marketers. [less ▲]

Detailed reference viewed: 26 (1 ULg)
Peer Reviewed
See detailInactivation of E. coli RNA polymerase by pyridoxal 5′-phosphate: Identification of a low pKa lysine as the modified residue
Bull, Paulina; Zaldivar, Josefina; Venegas, Alejandro et al

in Biochemical and Biophysical Research Communications (1975), 64(4), 1152-1159

The inactivation of E. coli RNA polymerase (3.3 × 10−7M) by pyridoxal 5′-phosphate (1 × 10−4M to 5 × 10−4M) is a first order process with respect to the remaining active enzyme. Studies of the variation ... [more ▼]

The inactivation of E. coli RNA polymerase (3.3 × 10−7M) by pyridoxal 5′-phosphate (1 × 10−4M to 5 × 10−4M) is a first order process with respect to the remaining active enzyme. Studies of the variation of the first order rate constant with the concentration of pyridoxal 5′-phosphate show that the inactivation reaction follows saturation kinetics. The formation of a reversible enzyme-inhibitor intermediate is postulated. Kinetic studies at different pH values indicate that the inactivation rate constant depends on the mole fraction of one conjugate base with pKa 7.9. The apparent equilibrium constant (association) for the inactivation reaction is independent of the pH and is 1.8 × 104 M−1. By electrophoretic and chromatographic analysis of enzyme hydrolyzates after pyridoxal 5′-phosphate and NaBH4 treatment only N-ε-pyridoxyllysine was found. It is postulated that a lysine ε-amino group with a low pKa is critical for the activity of the enzyme. [less ▲]

Detailed reference viewed: 31 (2 ULg)