Showing papers by "Université de Sherbrooke published in 1991"
TL;DR: The results were consistent with the polyneuropathy being due to the same mechanisms that are currently postulated to cause dysfunction in this syndrome of other organ systems (including the neuromuscular respiratory system).
536 citations
TL;DR: In this paper, a phenomenological approach based on the definition of a severity parameter R = t∗exp[T − 100)/14·75] which combines time, t (min), and temperature, T (°C), to express the severity of a given pretreatment, was developed.
274 citations
TL;DR: The mechanism and kinetics of the hydrogen evolution reaction were studied in on nickel-zinc alloy electrodes prepared by electrodeposition at controlled potential as discussed by the authors, and it was found that the reaction proceeds via the Volmer-Heyrovsky mechanism.
Abstract: The mechanism and kinetics of the hydrogen evolution reaction were studied in on nickel‐zinc alloy electrodes prepared by electrodeposition at controlled potential A series of electrodes containing 70 to 28% Ni was prepared Before the measurements, zinc was leached in alkaline solution Using the ac impedance technique, it was found that the reaction proceeds via the Volmer‐Heyrovsky mechanism, and the kinetic parameters of the process were determined With a decrease in the nickel content, the electrode becomes more active, and an increase in the real surface area is observed The surface morphology was studied using SEM and optical microscopy
251 citations
TL;DR: The social system of bighorn sheep appears to have been shaped by anti-predator and foraging strategies that rely upon learned traditions, and kinship appears to play a limited role.
211 citations
TL;DR: A new set of textural measures derived from the texture spectrum is presented, which extract textural information of an image with a more complete respect of texture characteristics (in all the eight directions instead of only one displacement vector used in the co-occurrence matrix approach).
208 citations
TL;DR: In this article, a review of the fundamental aspects involved in material processing using thermal plasma technology is given, focusing on the identification of the basic energy coupling mechanism in each case and principal characteristics of the flow and temperature fields in the plasma.
Abstract: A review is given of the fundamental aspects involved in material processing using thermal plasma technology. The description of plasma generating devices covers DC plasma torches, DC transferred arcs, RF inductively coupled plasma torches and hybrid combinations of them. Emphasis is given to the identification of the basic energy coupling mechanism in each case and the principal characteristics of the flow and temperature fields in the plasma. Materials processing techniques using thermal plasmas are grouped in two broad categories depending on the role played by the plasma in the process. Only typical examples are given of each type of process. These are grouped under two broad subsections dealing respectively with applications in which the plasma is used as a source of heat in high temperatures, and those in which the plasma is used as a source of chemically active species. The author also deals with plasma diagnostics and mathematical modeling and the role which they can play in the long term development of the technology. >
196 citations
TL;DR: In this paper, a new method of splitting exponential operators is proposed in the exponential form of the operator solution of the time-dependent Schrodinger equation, which is shown to be third-order accurate in the time increment.
150 citations
Harvard University1, University of Texas at Austin2, Stony Brook University3, University of Manitoba4, Université de Montréal5, University of Missouri6, Washington University in St. Louis7, Mayo Clinic8, United States Department of Veterans Affairs9, Icahn School of Medicine at Mount Sinai10, Université de Sherbrooke11, Winthrop-University Hospital12, Yeshiva University13
TL;DR: Although the Survival and Ventricular Enlargement Study population was selected for left ventricular dysfunction, the majority of patients who currently are judged clinically as unsuitable for thrombolytic therapy have a higher risk for adverse cardiovascular events.
Abstract: Objective. —To determine whether clinical selection for thrombolytic therapy for acute myocardial infarction results in a skewed population for subsequent adverse cardiovascular events. Design. —A comparison of the clinical features of the patients in the Survival and Ventricular Enlargement Study who either had or had not received thrombolytic therapy was conducted in both univariate and multiple logistic regression analyses. Setting. —Hospitalized patients experiencing acute myocardial infarction from 112 broadly representative, private, academic, and government hospitals in the United States and Canada. Patients. —All patients in the Survival and Ventricular Enlargement Study had had a recent myocardial infarction ( Intervention. —Thrombolytic therapy was administered to 733 patients and was not given to 1498. Main Outcome Measures. —The comparisons with respect to use of thrombolytic therapy were formulated after the completion of enrollment and indicated that the majority of patients did not receive thrombolytic therapy. Results. —The 1498 (67.1%) patients who did not receive thrombolytic therapy were at higher risk (older age, lower functional capacity, greater likelihood of a history of prior myocardial infarction, angina, diabetes, and hypertension) for subsequent cardiovascular events and, as anticipated, were more likely to have concomitant gastrointestinal and neurological diseases. A multiple logistic regression analysis indicated that older age, prior myocardial infarction, impaired functional status, employment status, diabetes, and neurological diseases were predictors of use of thrombolytic therapy. Conclusion. —Although the Survival and Ventricular Enlargement Study population was selected for left ventricular dysfunction, the majority of patients who currently are judged clinically as unsuitable for thrombolytic therapy have a higher risk for adverse cardiovascular events. (JAMA. 1991;266:528-532)
138 citations
132 citations
TL;DR: The occurrence of recorded seizures is higher in patients with PLEDs Plus than in those withPLEDs Proper or NPEDs, and the importance of recognizing RDs in scalp EEGs as transitional anomalies intercalated between inter-ictal PL EDs and ictal seizure discharges is emphasized.
126 citations
TL;DR: In this paper, the microstructural development of fly ash replacement pastes with progressive hydration was investigated using scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDXA).
TL;DR: It is found that the immune response to the 60-kd Ro antigen is heterogeneous, and the frequent immunodominance of anti-Ro antibodies targeted to conformational determinants suggests that native autoantigens may directly drive the autoimmune response.
Abstract: Anti-Ro antibodies are found in a large proportion of patients with systemic lupus erythematosus and primary Sjogren's syndrome. These antibodies also characterize neonatal lupus, subacute cutaneous lupus erythematosus, and vasculitis associated with Sjogren's syndrome and rheumatoid arthritis. Anti-Ro-positive sera may contain either or both of 2 sets of antibodies, recognizing either a 60-kd or a 52-kd polypeptide component of the Ro particle. We found in this study that the immune response to the 60-kd Ro antigen is heterogeneous. Some sera specifically recognize the native Ro antigen but fail to bind the corresponding denatured polypeptides. In addition, after immunodepletion using the denatured 60-kd Ro polypeptide, all anti-Ro-positive sera tested still contained high titers of antibodies recognizing conformational determinants on the Ro antigen. The frequent immunodominance of anti-Ro antibodies targeted to conformational determinants suggests that native autoantigens may directly drive the autoimmune response.
TL;DR: The present findings show that endothelin‐1 is capable of increasing vascular permeability in selected vascular beds including the airways, gastrointestinal tract and kidney, and suggest that PAF may mediate, in part, its action on permeability, but not its hypotensive action.
Abstract: 1. The objectives of the present experiments were to assess the effects of endothelin-1 on the macrovascular permeability in selected vascular beds, to study the involvement of platelet-activating factor (PAF) in vascular responses to endothelin-1 and to examine the vascular effects of combined administration of endothelin-1 and PAF in conscious rats. 2. Intravenous bolus injection of endothelin-1 (0.1-2 nmol kg-1) resulted in a dose-dependent biphasic change in mean arterial blood pressure (MABP) with initial transient hypotension followed by a prolonged pressor action. These changes were accompanied by a dose-dependent increase in haematocrit values. 3. Endothelin-1 (0.1 and 1 nmol kg-1) increased dose-dependently the vascular permeability of the trachea, upper and lower bronchi, stomach, duodenum, spleen and kidney (up to 240%) as measured by the extravasation of Evans blue dye. The permeability of pulmonary parenchyma, liver and pancreas was not affected significantly by endothelin-1 treatment. 4. Pretreatment of animals with the specific PAF receptor antagonist, WEB 2086 (1 mg kg-1, i.v.) or BN 52021 (10 mg kg-1, i.v.) reduced the endothelin-1 (1 nmol kg-1)-induced rise in haematocrit by about 50 and 30%, respectively. Both antagonists were highly effective at inhibiting protein extravasation in the stomach, duodenum and kidney. On the other hand, BN 52021, but not WEB 2086, significantly attenuated the effect of endothelin-1 on permeability in the lower bronchi and spleen. Neither WEB 2086 nor BN 52021 modified the changes in MABP evoked by endothelin-1.5. When low doses of endothelin-1 (0.1 nmolkg-')and PAF (0.19nmolkg-')were administered simultaneously, enhanced protein extravasation was detected in the upper and lower bronchi, whereas neither endothelin-1 nor PAF by themselves affected vascular permeability in these tissues. These changes occurred in the absence of significant changes in MABP.6. Combined administration of higher doses of endothelin-1 (1nmolkg-') and PAF (1.9nmolkg-') resulted in marked increases (up to 530%) in protein extravasation in the airways, pancreas, stomach and duodenum. The effect of endothelin-1 on permeability was not affected by PAF in the spleen, whereas it was completely inhibited by PAF in the kidney. Combined injection of endothelin-1 and PAF resulted in a slight, but significant increase in MABP.7. The present findings show that endothelin-1 is capable of increasing vascular permeability in selected vascular beds including the airways, gastrointestinal tract and kidney, and suggest that PAF may mediate, in part, its action on permeability, but not its hypotensive action. The present data also suggest that endothelin-1 and PAF can act in concert to increase vascular permeability in rat airways and gastrointestinal tract.
14 Apr 1991
TL;DR: An efficient procedure for searching such a large codebook deploying a focused search strategy, where less than 0.1% of the codebook is searched with performance very close to that of a full search is described.
Abstract: The application of algebraic code excited linear prediction (ACELP) coding to wideband speech is presented An algebraic codebook with a 20 bit address can be used without any storage requirements and, more importantly, with a very efficient search procedure which allows for real-time implementation The authors describe an efficient procedure for searching such a large codebook deploying a focused search strategy, where less than 01% of the codebook is searched with performance very close to that of a full search High-quality speech at a bit rate of 13 kbps was obtained >
TL;DR: It is indicated that ET-1 can directly stimulate prostacyclin release from endothelial cells probably through a receptor mediated mechanism.
TL;DR: It would appear that endothelin increases contractility and modifies twitch configuration in rat and rabbit papillary muscles and in a species, such as rabbit, that responds more to interventions that increase intracellular calcium.
Abstract: The actions of endothelin on the contractile and twitch configuration characteristics of rat and rabbit papillary muscles were evaluated before and after endocardial endothelium removal. In rabbit papillary muscles, endothelin produced a dose-dependent (10(-11) to 10(-7) M) increase in tension (T) (from 2.7 +/- 0.2 to 8.9 +/- 0.7 g/mm2, p less than 0.01), dT/dt, and Vmax (from 1.14 +/- 0.03 to 3.0 +/- 0.13 Lmax/sec, p less than 0.01), a decrease in time to peak tension (from 251 +/- 9 to 216 +/- 7 msec, p less than 0.05), and an increase in time to half relaxation (from 168 +/- 9 to 293 +/- 14 msec, p less than 0.01). Increasing calcium concentration in the bath from 1.25 to 15 mM greatly attenuated these changes. In the presence of propranolol (10(-5) M), endothelin increased all indexes of contractility but to a lesser extent (T = 2.6 +/- 0.3 to 6.5 +/- 0.2 g/mm2, p less than 0.01; Vmax = 1.16 +/- 0.10 to 2.06 +/- 0.10 Lmax/sec, p less than 0.01). Myocardial catecholamine depletion with reserpine had effects similar to those of propranolol. The myocardial contractile and twitch configuration characteristics of endothelin were similar to those of phenylephrine (10(-4) M), a strong stimulator of the phosphatidylinositol pathway and a moderate beta-adrenergic stimulator. The effects of phenylephrine and endothelin were modified in a similar manner by propranolol (10(-5) M). The presence of nicardipine (3 X 10(-7) M) decreased the absolute increase in contractility caused by endothelin but did not alter the percent change or shift the dose-response curve of endothelin. The actions of endothelin in rat papillary muscles studied at physiological calcium concentrations (Ca2+ = 1.25 mM) were less marked than those of rabbit studied at physiological calcium (Ca2+ = 1.25 mM) but similar to those of rabbit studied at high calcium concentrations (Ca2+ = 15 mM). Removing the endocardial endothelial layer of rabbit papillary muscles did not alter the absolute changes in contractility caused by endothelin but shifted the dose-response curve to the left and markedly altered the effects of endothelin on twitch configuration characteristics. Thus, it would appear that endothelin increases contractility and modifies twitch configuration. It does so more at lower rather than higher extracellular calcium concentrations and in a species, such as rabbit, that responds more to interventions that increase intracellular calcium.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: A method that avoids culture was devised to determine serovars of Chlamydia trachomatis, leaving two ambiguities that were resolved using alternate enzymes.
Abstract: A method that avoids culture was devised to determine serovars of Chlamydia trachomatis. Polymerase chain reaction was used first to amplify a part of the chlamydial genome that included the leader sequence and all four variable domains of the major outer membrane protein (MOMP) of the 15 serovars of C. trachomatis. The amplified DNA was then digested simultaneously with restriction endonucleases AluI and MspI and the resulting fragments separated on 10% polyacrylamide gels. After silver staining, a total of 13 characteristic patterns were observed for the 15 serovars, leaving two ambiguities that were resolved using alternate enzymes. Analysis of 40 clinical isolates revealed patterns indistinguishable from those of the prototype serovars including, unexpectedly, 5 Ba serovars. The same PCR procedure also allowed amplification of the MOMP gene of two avian Chlamydia psittaci and one Chlamydia pneumoniae isolates.
TL;DR: In this paper, the effects of single-electron interchain hopping on the mechanisms of propagation of correlations leading to long range ordering is analyzed in full details for the non-half-filled band case.
Abstract: We review the recent progress made in the application of the renormalization group method to the interacting quasi-one-dimensional electron gas. From the functional integral formulation of the partition function as expressed in terms of anticommuting Grassmann variables, the effects of single-electron interchain hopping on the mechanisms of propagation of correlations leading to long range ordering is analyzed in full details for the non-half-filled band case. Within a unified formalism, the scaling features of the purely one-dimensional correlations, the dimensionality crossover of both single and composite particles, the critical temperatures, and the responses functions are described.
TL;DR: The presence of the IGF‐I receptor and the absence of IGF‐II and insulin receptors are discussed in relation to the capacity of PA‐III cells to produce bone lesions on the L‐W rat.
Abstract: Four transplantable cell lines (PA-I, II, III, and IV) derived from four Lobund-Wistar (L-W) rats that manifested spontaneous prostate cancer have demonstrated metastatic capacity in visceral organs. Interestingly, PA-III cells, when deposited over the scapula or calvarium of the Lobund-Wistar rat, could produce lytic and blastic reactions on rat skeleton. Since growth factors and growth factor receptors have been implicated in bone remodeling, cancer biology, and metastatic growth of cancer cells, we have examined 1) the effects of insulin and insulin-like growth factors (IGF-I and IGF-II) on the proliferation of PA-III cells; and 2) the presence of specific receptors for these peptides. IGF-I (0.5 to 100 ng/ml), IGF-II (0.5 to 100 ng/ml), and insulin (0.5 to 10 micrograms/ml) stimulated tritiated thymidine uptake and increased the number of PA-III cells in culture. Receptor studies demonstrated the presence of specific bindings sites for IGF-I and II but not for insulin. The number and affinity of the receptor sites were: IGF-I (nb = 675 fmol/100 g protein, Kd = 0.56 nmol) and IGF-II (nb = 225 fmol/100 g protein, Kd = 0.71 nmol). Molecular characterization of IGF binding sites by polyacrylamide gel electrophoresis under denaturing conditions indicated only the presence for the type I IGF receptor. The presence of the IGF-I receptor and the absence of IGF-II and insulin receptors are discussed in relation to the capacity of PA-III cells to produce bone lesions on the L-W rat.
TL;DR: Observations are compatible with the hypothesis that an immune phenomenon is involved in the pathogenesis of melarsoprol-induced encephalopathy and very aggressive therapeutic schemes may result in higher toxicity, especially in patients with an impaired blood-brain barrier.
Abstract: Data on 598 patients with Trypanosoma brucei gambiense sleeping sickness, with abnormal cerebrospinal fluid (CSF) and treated with melarsoprol, were reviewed to determine risk factors for drug-induced encephalopathy. The incidence of melarsoprol-induced encephalopathy was increased in patients with trypanosomes present in the CSF, in patients with a high CSF lymphocyte count, and among patients in whom no trypanosomes were found in either the blood or the lymph node aspirate. Among patients with trypanosomes in the CSF, the risk of encephalopathy was similar whether or not they also had trypanosomes seen in the haemolymphatic system. Dimercaprol, a heavy metal chelator, did not reduce the case-fatality rate of patients with encephalopathy. These observations and others are compatible with the hypothesis that an immune phenomenon is involved in the pathogenesis of melarsoprol-induced encephalopathy. Whether the basic mechanism relates to deposits of immune complexes in the central nervous system or to the release of trypanosomal antigens which subsequently bind to brain cells and attract antibodies or T lymphocytes, the rapidity with which trypanosomal antigens are released may be critical, and very aggressive therapeutic schemes may result in higher toxicity, especially in patients with an impaired blood-brain barrier.
TL;DR: Inferential statistics demonstrated that family needs and situational anxiety were significantly related (P less than 0.0002) and worries, trait anxiety, age and family needs explained 38% of the variation of situational anxiety.
Abstract: The purpose of this study was to explore the perceived needs and anxiety levels of adult family members of intensive care unit (ICU) patients. The study was conducted over a 3-month period, on a convenience sample of 166 subjects selected from the total adult population of family members visiting an ICU patient in three Sudbury hospitals. Data were gathered using a self-report questionnaire, the Critical Care Family Needs Inventory (CCFNI) and Spielberger's State Trait Anxiety Inventory (STAI). Interviews were conducted in French or English according to the subject's preference. The major variables examined were: family needs; state and trait anxiety; on-site sources of worry; spiritual needs; level of knowledge of ICU from past experience or pre-surgery education; sociodemographic data. The Situational Anxiety Scale yielded a mean score of 45.24 and the Trait Anxiety Scale a mean score of 37.3. Inferential statistics demonstrated that family needs and situational anxiety were significantly related (P less than 0.0002). Furthermore, worries, trait anxiety, age and family needs explained 38% of the variation of situational anxiety. As well, spiritual needs and situational anxiety explained 33% of the variation of family needs.
TL;DR: Bouchard et al. as discussed by the authors discussed the characterization of the water-soluble fractions by standard, thermal (DSC) and spectroscopic (DRIFT) methods in terms of the effect of the severity of the treatment on the chemical structure of the soluble wood polymers.
TL;DR: The present results demonstrate that DuP 753 is a potent nonpeptide antagonist with high affinity, specificity, and selectivity for the angiotensin receptor.
Abstract: 2-n-Butyl-4-chloro-5-hydroxy-methyl-1-[(2'-(1H)-tetrazol-5-yl)biph enyl-4- yl)methyl]imidazol potassium salt (DuP 753) is a nonpeptide angiotensin II receptor antagonist that inhibits the contractile effects of angiotensin II competitively and shows pA2 values of 8.27 on the rabbit aorta and jugular vein, 8.66 on the rat portal vein and stomach, 8.19 on the rat urinary bladder, and 8.36 on human colon, ileum, and urinary bladder. This agent (more than 10(-5) M) exhibits no agonistic activity and does not affect the contractile effects of norepinephrine, acetylcholine, bradykinin, desArg9-bradykinin, substance P, neurokinin A, neurokinin B, or bombesin in the various tissues. The present results demonstrate that DuP 753 is a potent nonpeptide antagonist with high affinity, specificity, and selectivity for the angiotensin receptor.
TL;DR: The results indicate that the profile of NPY's neurobehavioral actions is more complex than previously reported and suggest that the peptide might be implicated functionally in a variety of neurophysiological processes.
TL;DR: Mutants defective in pRB binding were unable to immortalize primary rat embryo fibroblasts, suggesting that association with pRB is an important component of immortalization mediated by polyomavirus large T.
Abstract: To clarify the relationship between the various activities of the polyomavirus large T antigen and the contribution of this oncogene to neoplastic transformation, we constructed a series of mutants with small deletions or single-amino-acid substitutions in two separate regions of the protein. These sequences were targeted because they showed considerable similarity to conserved regions 1 and 2 of adenovirus E1A which are thought to be binding sites for the retinoblastoma gene product (pRB). The pRB-binding properties of the large T mutants were assessed with an in vitro coimmunoprecipitation assay. pRB binding was readily detected with wild-type large T, but coprecipitation was completely abolished by as little as a single amino acid substitution (Asp-141----Glu or Glu-146----Asp) in region 2 of the polyomavirus large T antigen. Mutants defective in pRB binding were unable to immortalize primary rat embryo fibroblasts, suggesting that association with pRB is an important component of immortalization mediated by polyomavirus large T. The mutations in region 1 affected pRB binding only marginally, yet some of them severely impaired immortalization, indicating that pRB binding may be essential but not sufficient for immortalization.
TL;DR: In this article, the time-dependent Schrodinger equation describing the interaction of an HCN molecule with intense, ultrashort, chirped infrared laser pulses is solved numerically.
TL;DR: It appears that kinins act on various B2-receptor subtypes or by different action mechanisms, and high concentrations of antagonists block bradykinin completely in the rabbit jugular vein but not in the guinea pig ileum, suggesting that Kinins stimulate the moderately sensitive tissues by two mechanisms.
Abstract: Thirty-seven compounds were tested as antagonists of kinin B2- and B1-receptors to identify the chemical changes required to obtain antagonism, improve antagonist affinity, and eliminate residual agonistic activities. Apparent affinity of antagonists was evaluated in terms of pA2 on the rabbit jugular vein, the dog carotid and renal arteries, the hamster urinary bladder, the guinea pig ileum, the rat vas deferens, the guinea pig trachea, and the rabbit aorta, using bradykinin and desArg9-bradykinin as B2- and B1-receptor activators. Replacement of Pro7 of bradykinin with D-Phe leads to antagonism; substitution of Pro3 by Hyp and extension of the peptide chain at the N-terminal with a D-Arg residue improves the affinity of antagonists; acetylation of N-terminal amine function reduces residual agonistic activity; these changes, combined with the replacement of Phe8 by Leu as in Ac-D-Arg[Hyp3,D-Phe7,Leu8]-bradykinin, led to potent full B2-receptor antagonists. Affinity of antagonists differs markedly between highly sensitive (rabbit jugular vein, dog carotid and renal artery), moderately sensitive (hamster urinary bladder, guinea pig ileum, and rat vas deferens), and insensitive preparations (the guinea pig trachea) in which antagonists act as potent stimulants. High concentrations of antagonists block bradykinin completely in the rabbit jugular vein but not in the guinea pig ileum, suggesting that kinins stimulate the moderately sensitive tissues by two mechanisms, of which only one is blocked by antagonists. It thus appears that kinins act on various B2-receptor subtypes or by different action mechanisms.
TL;DR: In this article, the authors used X-ray crystallography and FTIR of the solid residues to probe the mechanism of conversion of cellulose into liquid products, and found that the transition from a cellulosic to a dehydrated structure is much more clean cut in the case of the purified cellulose and the yield of levoglucosan (i.e cyclised anhydro pyranose rings) is greater.
TL;DR: The present results suggest that neurokinins act on the rat mesenteric bed by increasing the perfusion pressure of the venous vasculature via activation of NK-3 receptors.
TL;DR: Observations suggest that the addition of taurine to TPN solutions could play a role in the prevention of altered biliary function associated with AA solutions.
Abstract: A decrease in the formation/secretion of bile has been well documented in animals on total parenteral nutrition (TPN). Either an excess or an imbalance of amino acids (AA) has been most often implicated. In view of recent work showing that taurine promotes bile flow, bile acid secretion, and protects against hepatotoxic bile acids, the effect of adding taurine (15 mg/dL) to an AA solution was examined in guinea pigs on TPN for 3 days. The TPN-taurine group had a larger bile flow than the group without taurine and had bile acid secretory rates (BASR) similar to those of controls who were on saline by central catheter and had free access to food. Bile composition showed an increase in the secondary bile acid, 7-ketolithocholate and a concomitant decrease in chenodeoxycholate (CDC) in both experimental groups. Taurine led to a reversal of the usual predominance of glycine over taurine conjugated bile acids as well as to increases in HCO3 in cholesterol secretion. In response to a challenge with a large load of CDC, the TPN-taurine animals increased their BASR beyond those observed in the two other groups. These observations suggest that the addition of taurine to TPN solutions could play a role in the prevention of altered biliary function associated with AA solutions.