Showing papers by "Université de Sherbrooke published in 1986"
TL;DR: The main effects of near-ultraviolet and visible light on cellular DNA are reviewed with emphasis on base lesions, oligonucleotide single-strand breaks and DNA-protein cross-links.
161 citations
TL;DR: Support for the involvement of singlet excited oxygen is obtained from azide inhibition and the formation of the specific singlet oxygen product with cholesterol in the case of the manganese complex.
Abstract: — Sulfonated phthalocyanine and a series of its metal chelates in combination with red light irradiation led to the degradation of L-tryptophan in oxygenated aqueous solution. The photoproducts and the rate of transformation of L-tryptophan are compared with hematoporphyrin and rose bengal sensitized photooxidation. In all cases the primary photoproducts are characterized as cis and trans-3a-hydroperoxy-l,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid. Support for the involvement of singlet excited oxygen is obtained from azide inhibition and the formation of the specific singlet oxygen product with cholesterol. We observed the contribution of another pathway in the case of the manganese complex.
140 citations
TL;DR: In this article, the results indicate the presence of dynamic stall at tip speed ratio less than 4, and that helicopter blade aerodynamics can be used in order to explain some aspects of the phenomenon.
Abstract: This paper presents the results of an experimental investigation on a driven Darrieus turbine rotating at different tip speed ratios. For a Reynolds number of 3.8 x 10/sup 4/, the results indicate the presence of dynamic stall at tip speed ratio less than 4, and that helicopter blade aerodynamics can be used in order to explain some aspects of the phenomenon. It was observed that in deep stall conditions, a vortex is formed at the leading edge; this vortex moves over the airfoil surface with 1/3 of the airfoil speed and then is shed at the trailing edge. After its shedding, the vortex can interact with the airfoil surface as the blade passes downstream.
134 citations
TL;DR: NK-A receptors for neurokinins (which are present in the tracheo-bronchial tree) are also to be found in pulmonary vessels and mediate contraction of arterial vascular smooth muscle, an interesting property of Neurokinins.
134 citations
TL;DR: In this article, the side chain contributions to Vo and CPO were obtained as the difference between the properties of the various amino acids and those of glycine, both in water and in 8M urea.
Abstract: The limiting partial molar volumes Vo and heat capacities Cpo of 20 amino acids have been determined in water and in 8 molar urea at 25.0°C using flow calorimetry and flow densimetry. The side chain contributions to Vo and Cpo were obtained as the difference between the properties of the various amino acids and those of glycine, both in water and in 8M urea. The solvent accessible surface area of the amino acid residues were obtained using a method developed by Hermann, and the total surface areas were separated into their hydrophobic AHb and hydrophilic components. In water, Cpo values for the various residues Cpo(R) were found well correlated with AHb, though much less so in the urea solution. Hence, Cpo(R) values, in water yield a good estimate of side chain hydrophobicity, but the (water→urea) transfer heat capacities appear strongly affected by specific solvation effects in the urea solution.
133 citations
TL;DR: The results suggest that group C adenovirus infections in childhood result in the persistence of the viral genome in circulating lymphocytes.
Abstract: Human peripheral blood lymphocytes from healthy adults, cord blood lymphocytes, and lymphoblastoid cell lines were screened by hybridization for the presence of group C adenovirus DNA sequences. In 13 of 17 peripheral blood lymphocyte samples from adults, 1 of 10 cord blood samples, and seven of seven lymphoblastoid cell lines tested, results were positive for Group C adenovirus DNA (adenovirus 1 [Ad1], Ad2, Ad5, or Ad6). About 1 to 2% of the lymphocytes carried 50 to 100 viral genome copies per positive cell, as estimated by in situ hybridization. Infectious virus representing all members of group C were recovered, but cultivation in the presence of adenovirus antibody did not cure the cells of free viral genomes. Viral DNA was found in B, T, and N cells but only in 1 of 10 cord blood samples. The results suggest that group C adenovirus infections in childhood result in the persistence of the viral genome in circulating lymphocytes.
130 citations
TL;DR: The results suggest that the constrictor effect of NPY on guinea pig coronary vessels results from a direct effect on vascular smooth muscle cells, is mediated by specific receptors and is likely to involve the participation of extracellular calcium ions.
119 citations
TL;DR: The newly discovered bradykinin antagonists are however specific for the kinins, since they do not interfere with the myotropic effects of angiotensin or substance P (SP) in the various preparations.
87 citations
TL;DR: Results indicate that NPY located in the hypothalamo-hypophyseal system of the frog may act as a melanotropin-release inhibiting factor.
84 citations
TL;DR: The measurement of levels of fibronectin and procollagen 3 in bronchoalveolar lavage fluid assesses fibrogenic activity of alveolitis and should be useful to predict its progression in a fibrotic process.
77 citations
TL;DR: In this paper, it was shown that the extents of solubilization of both holocellulose and lignin are linearly related to overall conversion within the temperature range 150-270°C and up to conversions of 83%.
Abstract: This paper shows that liquefaction (i.e. solubilization) of lignocellulosics in aqueous phase and in the absence of catalysts results in two general correlations. The extents of solubilization of both holocellulose and lignin are linearly related to overall conversion within the temperature range 150–270°C and up to conversions of 83%.
Cet article presente l'evidence experimentale concernant deux correlations generales observees lors de la liquefaction (i.e. solubilisation) des matieres lignocellulosiques en phase aqueuse et en absence de catalyseurs. Les niveaux de solubilisation de l'holocellulose et de la lignine sont relies de facon lineaire a la conversion dans la plage de temperature comprise entre 150 et 270°C et pour des conversions allant jusqu'a 83%.
TL;DR: Brand maps are derived directly from verbalizations about brands (What do you think of brand X,?) as discussed by the authors, and the resulting brand scores seem to meet a number of reliability criteria and to converge well to those derived from more structured measures.
TL;DR: Except for breast tenderness (Diane greater than Androcur), amenorrhea, and weight gain, (Androcur greater than Diane), the incidence of side effects was comparable in both groups.
TL;DR: This paper study the simplest rigidity-percolation model, namely the two-dimensional central-force model, distinguishing it from the "elasticity percolation" universality class mentioned above.
Abstract: It is shown that the diluted two-dimensional central-force problem belongs to a new class of percolation problems. Geometric properties such as the fractal dimension of the backbone, the correlation-length exponent, and the connectivity are completely different from those of previously studied percolation problems. Explicit calculations of the backbone and the construction of an algorithm which identifies the infinite rigid cluster clearly demonstrate the absence of singly connected bonds, the overwhelming importance of loops, and the long-range nature of the rigidity.
TL;DR: The terminal oxidase of human placental aromatase is indeed a cytochrome P-450-type monooxygenase and the multistep aromatization reaction of C19 androstenes is catalyzed by a single enzyme, and aromatized 19-norsteroids reported by other authors must be due to a different aromat enzyme.
Abstract: The hemoprotein component of human placental aromatase (estrogen synthetase) has been purified to a high degree of homogeneity by a combination of affinity and adsorption chromatography on aminohexyl-Sepharose, concanavalin-A–Sepharose, and hydroxyapatite. The monomeric form of the enzyme has an Mr of 55000 ± 1000 as estimated by sodium dodecyl sulfate gel electrophoresis. Its absolute spectrum shows a high-spin Soret band at 394 nm while its reduced, CO-difference spectrum has a maximum at 447 ± 1 nm. Full reconstitution of aromatase activity was obtained when it was recombined with a homogeneous preparation of the higher-Mr form of either human placental, or bovine hepatic NADPH–cytochrome P-450 reductase. Critical factors for purification of the very unstable, membrane-bound hemoprotein with good retention of activity were, besides the chromatographic sequence, the use of the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps) during the solubilization, and the stabilizing effect of the aromatase substrate, 4-androstene-3,17-dione, throughout the procedure. In the presence of NADPH, the reconstituted enzyme system smoothly aromatizes 19-oxoandrostenedione, 19-hydroxyandrostenedione and androstenedione in this order of reactivity. The same reconstituted system also aromatized testosterone, but it was inactive towards 19-nor-androstenedione. Known cytochrome P-450 inhibitors decreased its activity. We conclude: (a) the terminal oxidase of human placental aromatase is indeed a cytochrome P-450-type monooxygenase; (b) the multistep aromatization reaction of C19 androstenes is catalyzed by a single enzyme; (c) aromatization of 19-norsteroids reported by other authors must be due to a different aromatase. Experimental data obtained with the reconstituted enzyme are fully compatible with the concept of a reaction mechanism for the aromatization sequence involving an all-trans, antiparallel elimination of the 19-methyl group, the 2β proton and the 1α proton, rather than the 1β proton, as generally assumed.
TL;DR: The present findings suggest that bradykinin and B2 receptor antagonists are converted by carboxypeptidases into biologically active B1 receptor agonist or antagonists.
TL;DR: An iterative algorithm for solving a convex quadratic program with one equality constraint and bounded variables and preliminary testing suggests that this approach is efficient for problems with diagonally dominant matrices.
Abstract: In this paper we propose an iterative algorithm for solving a convex quadratic program with one equality constraint and bounded variables. At each iteration, a separable convex quadratic program with the same constraint set is solved. Two variants are analyzed: one that uses an exact line search, and the other a unit step size. Preliminary testing suggests that this approach is efficient for problems with diagonally dominant matrices.
01 Aug 1986
TL;DR: In this paper, the volumes, enthalpies, and heat capacities of Cetyltrimethylammonium bromide (CTAB) in water were studied up to 0.3 mol kg −1.
Abstract: The volumes, enthalpies, and heat capacities of cetyltrimethylammonium bromide (CTAB) in water were studied up to 0.3 mol kg −1 . At 25°C, the apparent molar volumes ( V 2 , φ) in the postmicellar region remain constant while the heat capacities ( C P ,2, φ ) increase and the relative enthalpies decrease around 0.15 mol kg −1 . These changes in the thermodynamic properties are amplified when benzene is used as a probe. The effects of counterion, temperature, D 2 O, and added electrolyte were also investigated. For the chloride homolog (CTAC) the postmicellar transition is observed around 0.3 mol kg −1 at 25°C. An increase in temperature shifts the transition to lower molalities and this transition seems to vanish around 50°C. Changing the solvent to D 2 O has the same effect as lowering the temperature on the thermodynamic functions but shifts the transition only slightly to higher concentration. The addition of an electrolyte has a large effect on the transition concentration, the lowering being larger with KBr than with KCl. Through EMF measurements as the Br − is shown to be replaced by Cl −1 on the micellar surface upon the addition of KCl. The postmicellar transition can be interpreted in terms of changes in counterion binding to the micelles and consequent loss in the structural hydration cosphere. The effect is not necessarily correlated to the growth of the micelles.
TL;DR: A semiphenomenological model can describe the gap-state motion of hot electrons through films and is proposed to explain the unusual behavior of the transmitted current near 0 eV and to estimate the diffusion constant of nonthermalized electrons in the gap states.
Abstract: We report direct measurements of electron conduction within gap states of thin films of Ar, ${\mathrm{N}}_{2}$, and n-hexane. Since these materials have a conduction-band edge (the energy at the bottom of the conduction band) above the vacuum level, we have been able to study the transfer of electrons at ultralow energies (0.05--0.8 eV) within the energy gap by high-resolution electron transmission spectroscopy. We found the transmission to be strongly influenced by gap states. For instance, our Ar films which were fairly well crystallized nevertheless exhibited quantum tunneling with unusually long penetration lengths. We attribute this to a low density of gap states. Our ${\mathrm{N}}_{2}$ films, on the other hand, had a considerable density of gap states through which electrons could diffuse. We propose a model to explain the unusual behavior of the transmitted current near 0 eV and to estimate the diffusion constant of nonthermalized electrons in the gap states. In n-hexane films, finally, conduction via such states was accompanied by strong electron inelastic scattering events. These latter lead to a quick saturation of the current with film thickness. We generalize our model to account for this behavior. This semiphenomenological model can describe the gap-state motion of hot electrons through films.
TL;DR: In this article, it was shown that rapid hydrolysis can be achieved by passage of aqueous cellulosic suspensions through capillaries followed by sudden decompression and post-treatment under dilutes acid conditions.
Abstract: The objective of this investigation is to show that rapid hydrolysis can be achieved by passage of aqueous cellulosic suspensions (2–10% solids) through capillaries followed by sudden decompression and post-treatment under dilutes acid conditions.
Through detailed experimentation within the 200–240°C temperature range and at low sulfuric acid concentrations (0.2–1.0% w/w) it was found that liquefaction of the cellulose proceeds via extensive formation of soluble oligomeric intermediates.
A simple kinetic model has been developed to explain the liquefaction-saccharification patterns of the cellulose. The sequence considered is:
Cellulose Oligo-derivatives Glucose Decomposition products
Quantitative values of the rate constants have been determined and a discussion on the selectivity of the overall reaction sequence is presented.
L'objectif de ce travail est de montrer que l'hydrolyse de la cellulose peut ětre effectuee par passage rapide de suspensions aqueuses (ayant 2 a 10% de solides) a travers de capillaires suivi d'une decompression soudaine et post-traitement en presence d'acides dilues.
Dans la plage de temperatures comprise entre 200 et 240°C et a des concentrations d'acide sulfurique de 0.2 a 1.0% (base ponderale) nous avons trouve que la liquefaction de la cellulose procede par voie de formation d'oligomeres solubles.
Un simple modele cinetique developpe afin d'expliquer les profits de liquefaction-saccharification de la cellulose. La sequence reactionnelle consideree peut ětre representee par:
Cellulose Oligo-derives Glucose Produits de decomposition
Des valeurs quantitatives des constantes cinetiques ont ete determinees. Une discussion sur la selectivite de la reaction d'hydrolyse est presentee.
TL;DR: In this paper, the synthesis of enantiomeric hydroxy epoxide synthons possessing a quaternary gem-dimethyl carbon center was reported, starting with the commercially available Pantolactone and using three different pathways.
TL;DR: A study on the base-catalyzed intramolecular Michael addition of β-ketoester-ynone 1 (n′ = 1−2, n = 0−3) is reported in this paper.
TL;DR: In this paper, a light-tight, hermetically sealed module for use in high resolution positron emission tomography systems is described, which contains two 3×5×20 Bismuth Germanate (BGO) scintillators, each with its own 3×3 mm silicon avalanche photodiode.
Abstract: A light-tight, hermetically sealed module for use in high resolution positron emission tomography systems is described. The module has external dimensions 3.8×13.2×33 mm and contains two 3×5×20 Bismuth Germanate (BGO) scintillators, each with its own 3×3 mm silicon avalanche photodiode. When stacked, the vertical packing fraction is 80%. As measured with a 137Cs (662 keV) source, the typical energy resolution is 20% at 22°C, reducing to 16% at 0°C. The single detector time resolution for the 22Na gamma at 511 keV is typically less 20 ns at 22°C, reducing to less than 15 ns at 0°C. Further cooling does not improve the performance since the emission time of light from BGO increases at lower temperature. Preliminary results with Gadolinium Orthosilicate show similar energy resolution, better timing resolution (under 10 ns), but as is known, a slightly poorer photofraction and stopping power.
TL;DR: New bounds for the exponent characterizing the amplitude of the resistance noise near the percolation threshold of discrete random networks are found anduum corrections to these exponents for the random-void class of systems are calculated within the nodes-links-blobs model of percolating networks.
Abstract: New bounds for the exponent characterizing the amplitude of the resistance noise near the percolation threshold of discrete random networks are found. The difference between the lower and upper bounds is very small so that an accurate estimate of the noise exponent can be obtained in all dimensions. Continuum corrections to these exponents for the random-void class of systems are then calculated within the nodes-links-blobs model of percolating networks.
TL;DR: The increase of magnesium andManganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation.
Abstract: Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation.
TL;DR: Micturitional reflexes are studied in 46 unanesthetized adult male cats spinalized at C5‐C6 17 to 125 days previously and in eight intact central nervous system chloralosed cats that were used as controls.
Abstract: We studied micturitional reflexes in 46 unanesthetized adult male cats spinalized at C5-C6 17 to 125 days previously and in eight intact central nervous system chloralosed cats that were used as controls. Urethral pressure profiles, cystosphincterograms with the urethrovesical junction opened and closed, and mechanograms of detrusor and circular and longitudinal urethral muscles were performed. The effect of vesical, urethral, pelvic, or pudendal anesthesia and vesical and urethral mechanical stimulation were studied.
Our results suggest that spinalization produces two major types of neurourologic disorders: (1) weakness of detrusor contractor reflexes (vesicovesical and urethrovesical contraction reflexes) and (2) exaggeration of urethral contractor reflexes (urethrourethral contraction reflex, guarding reflex). Secondarily the weakness of detrusor contractions diminishes the efficiency of the urethral reflex relaxation needed for voiding (vesicourethral relaxation reflex).
Because of these abnormalities, two main syndromes appear: (1) underactive detrusor function and (2) detrusor sphincter dyssynergia. Isolated peripheral manipulations of the bladder or urethra do not improve micturition: (1) increase in detrusor contraction strength induces detrusor sphincter dyssynergia, and (2) relaxation of the external sphincter facilitates voiding, but urinary retention persists.
It is proposed that spinalization produces a central micturitional dysreflexia responsible for the peripheral dysfunction, and treatment must be oriented toward the central dysreflexia rather than the peripheral dysfunction.
TL;DR: In this article, a large scale, 1500 kg/h, SO2-catalysed prehydrolysis of coniferous wood chips, samples then being hydrolyzed by a wood-saccharifying enzyme system followed by fermentation to ethanol in the laboratory.
Abstract: This paper reports studies of large scale, 1500 kg/h, SO2-catalysed prehydrolysis of coniferous wood chips, samples then being hydrolyzed by a wood-saccharifying enzyme system followed by fermentation to ethanol in the laboratory. Hemicellulose hydrolysis using SO2 catalyst (prehydrolysis) was found to be more effective than steam alone (autohydrolysis). Prehydrolysis time was 2 min, with steam pressure at 1.2 to 1.7 MPa (175 to 250 psig), and SO2 catalyst 2.0 to 2.6% on dry wood. The amount of sugars recovered upon enzyme saccharification of the prehydrolysed wood was about 70% of the weight of the wood. When these combined hemicellulose and cellulose sugars were fermented by a pentose-fermenting strain of yeast,Pichia stipitis R, 372 L ethanol/tonne of (dry) wood was obtained.
Patent•
13 Nov 1986TL;DR: In this article, an improved process for the wet oxidation of water soluble organic pollutants or of an aqueous suspension of organic pollutants was proposed, which consisted in forming a fine mist of the polluted aiquous phase in the presence of the oxidizing gas, and then the formed mist was introduced into a heated reaction chamber under pressure, thereby enhancing the rate of the destructive oxidation of the organic pollutant by the increase in mass transfer between the gaseous phase and the aiqueous mist, the reaction temperature being selected to favor rapid destruction of the pollutant without the formation
Abstract: The present invention relates to an improved process for the wet oxidation of water soluble organic pollutants or of an aqueous suspension of organic pollutants. In the contacting of an oxidizing gas and a polluted aqueous phase, the improvement comprises forming a fine mist of the polluted aqueous phase in the presence of the oxidizing gas, thereby increasing the interfacial area between the gas and the polluted aqueous phase. Then the formed mist is introduced into a heated reaction chamber under pressure, thereby enhancing the rate of the destructive oxidation of the organic pollutant by the increase in mass transfer between the gaseous phase and the aqueous mist, the reaction temperature being selected to favor rapid destruction of the pollutant without the formation of stable intermediate reaction products. After destruction of the pollutants, the reaction mixture is allowed to flash off at a pressure lower than the reaction pressure.
TL;DR: The results demonstrate that selective reductions of retinal dopamine and its metabolites can be obtained with a single intravitreal injection of 300 micrograms 6-OHDA in rabbits, lending support to the hypothesis that DA acts as a mediator of lateral inhibition in the retina.
TL;DR: By comparing to experiment, it is shown that the results correctly describe not only the order of magnitude of V0(n), but also the shape of the curve, which shows a minimum at n = 1.2 1022 atoms/cm3.
Abstract: The energy V0 of the quasi-free electron state in liquid argon is calculated as a function of the number density n in the range (0.001 ÷ 0.021) A-3. In the calculation, Lekner's theory for the scattering of excess electrons in liquid argon is followed, but modern, first-principles pseudopotentials are used. By comparing to experiment, it is shown that our results correctly describe not only the order of magnitude of V0(n), but also the shape of the curve, which shows a minimum at n = 1.2 1022 atoms/cm3. These new results are in much closer agreement with experimental data than other existing calculations.