Showing papers by "Université de Montréal published in 1981"

Is Variant Angina the Coronary Manifestation of a Generalized Vasospastic Disorder

Abstract: IN VARIANT angina, myocardial ischemia is caused by transient coronary-arterial spasm.1 , 2 Although altered adrenergic activity has been proposed as the cause of coronary spasm3 , 4 and high circu...

Insulin and insulin receptors in rodent brain.

Abstract: While insulin effects on the central nervous system (CNS) mediated through hypoglycaemia are well known, direct insulin effects on the CNS remain controversial. Recently, we found insulin receptors in all areas of the rat brain, with highest concentrations in the olfactory bulb, cerebral cortex and hypothalamus; all areas involved in feeding. Insulin receptors in brain were, by multiple criteria, similar to insulin receptors on classical target tissues for insulin, such as liver and fat. Insulin itself has been identified in the rat brain at concentrations on average ten times higher than in plasma. Highest concentrations were found in the olfactory bulb and hypothalamus. Brain insulin was indistinguishable from purified insulin by its behaviour in the radioimmunoassay, radioreceptor assay, bioassay and gel chromatography. In two experimental models representing extremes of plasma insulin concentrations (obese hyperinsulinaemic mice and diabetic insulinopenic rats) there were no significant changes in the concentration of insulin receptors in brain while liver receptors were modified in the expected way. This may reflect the protective influence of the blood-brain barrier or some special quality of brain insulin receptors. Insulin concentrations in brain were also unchanged in both models, which is probably indicative of the local synthesis of insulin. The role of insulin in the CNS is unknown. Besides well known metabolic actions of insulin, new roles can be postulated such as neurotransmission, neuromodulation and paracrine signalling.

Sexual Dimorphism in the Development, Emergence, and Agenesis of the Mandibular Third Molar

Abstract: Bilateral agenesis was encountered in about 9% of the cases, with no significant sexual difference. The right and left mandibular third molars had the same pattern of development and emergence. The slight advance of girls over boys at the crown-completion stage was similar to previous observations on other mandibular teeth, particularly the second molar. The root development course of the third molar was faster in males than in females; this sexual dimorphism was much greater for retarded cases than for advanced cases. At the apex closure, the difference between median ages of males and females was 1.5 yr. Alveolar emergence tended to occur at a lower developmental stage in advanced cases compared with retarded cases.

Cerebellar Afferent Systems

Abstract: The sections in this article are: 1 Mossy Fiber Afferent Systems 11 Direct Spinocerebellar Systems 12 Vestibulocerebellar Projection 13 Trigeminocerebellar Projection 14 Pontocerebellar System 15 Reticulocerebellar Projections 16 Nucleocortical Projection 2 Climbing Fiber Afferent Systems 21 Structure and Ultrastructure of Inferior Olive 22 Afferent Projections to Inferior Olive 23 Olivocerebellar Projection 24 Physiology of Inferior Olive 25 Summary 3 Aminergic Afferent Projections to Cerebellum 31 Noradrenergic System 32 Serotonergic Afferent System 33 Summary 4 Responses of Cerebellar Neurons to Exteroceptive and Proprioceptive Stimuli 41 Responses of Neurons in Cerebellar Cortex 42 Responses of Neurons in Deep Cerebellar Nuclei 43 Summary 5 Responses of Cerebellar Neurons to Visual, Auditory, and Vestibular Stimuli 51 Responses to Visual Stimuli 52 Responses to Auditory Stimuli 53 Responses to Vestibular Stimuli 6 Question of Somatotopy 61 Somatotopic Distribution of Responses Evoked by Peripheral Afferent Fibers 62 Somatotopic Distribution of Responses Evoked by Descending Pathways 63 Basis for Spatial Distribution of Responses 64 Comments 7 Summary 71 Mossy Fiber and Climbing Fiber Systems: Similarities and Differences

Bregman's balancing method

Abstract: In this paper we observe that most of the independently discovered balancing methods, used in transportation planning and in other fields, are in fact special cases of a method of Bregman. Examples include the usual Kruithof or Furness method, the Evans-Kirby three dimensional balancing procedure, the Murchland multiproportional balancing procedure, the Osborne or Grad method for preconditioning matrices, the Jefferson-Scott procedure for gravity models with inequality constraints, and the method considered by Macgill for partially constrained gravity models. The convergence of all of these methods follows from Bregman's general result.

Differences in Response Among Inbred Mouse Strains to Infection with Small Doses of Mycobacterium bovis BCG

Abstract: Intravenous infection of six inbred mouse strains with small doses of dispersed cells of Mycobacterium bovis BCG (15.5 x 10(3) or 15.5 x 10(4) colony-forming units) separated them into resistant (C3H/HeCr, A/J, and DBA/2) and sensitive (B10.A, C57BL/6, and BALB/c) strains as assessed by the magnitude of bacterial multiplication in the spleens at 28 days. The two groups were more sharply separated after infection with the lower dose of BCG (15.5 x 10(3) colony-forming units), which allowed for true multiplication of the bacteria in the spleens of permissive hosts, expressed as the ratio of the number of BCG recovered from the spleens to the number of BCG injected. This coefficient of increase was less than 1 in resistant strains, whereas it was higher than 2.5 in sensitive strains. Significant splenomegaly developed only in mice of the sensitive strains infected with BCG when compared with uninfected controls. There was no correlation between the magnitude of the delayed-type hypersensitivity (DTH) to BCG and susceptibility to infection: DTH was absent in both the sensitive and the resistant strains when the smaller dose of BCG was used for infection. Moreover, significant DTH was detected in animals of the most sensitive (BALB/c) as well as of the most resistant (C3H/HeCr) strain when the higher dose of BCG (15.5 x 10(4)) was used for immunization. These results document significant genetic differences in the ability of inbred mice to inhibit bacterial multiplication after infection with small dispersed doses of BCG. Resistance to BCG multiplication, in this model, does not appear to be related to the establishment of DTH.

Cordierite-garnet-H 2 O equilibrium: A geological thermometer, barometer and water fugacity indicator

Abstract: The high-grade assemblage Cd-Ga-Si-Qz can be thermodynamically modelled from available calorimetric data on the metastable reaction: (I) $$3 MgCd \rightleftarrows 2 Py + 4 Si + 5 Qz$$ naturalK D Fe-Mg between garnet and cordierite and experimental results on cordierite hydration. In the system SiO2-Al2O3-MgO-H2O, reaction (I) becomes (II) $$3 MgCd \cdot nH_2 O \rightleftarrows 2 Py + 4 Si + 5 Qz + 3 nH_2 O$$ . However, hydrous cordierite is neither a hydrate nor a solid solution between water and anhydrous cordierite and when nH2O (number of moles of H2O in Cd) is plotted against $$P_{H_2 O} $$ , the resulting isotherms are similar to adsorption isotherms characteristic of zeolitic minerals. Reaction (II) can thus be considered as a combination of reaction (I) with a physical equilibrium of the type nH2O (in Cd)⇆nH2O (in vapor phase). Starting from a point on equilibrium (I), introduction of H2O into anhydrous Mg-cordierite lowers the chemical potential of MgCd and hence stabilizes this mineral to higher pressure relative to the right-hand assemblage in reaction (I). The pressure increment of stabilization,ΔP, above the pressure limit of anhydrous cordierite stability at constantT, has been calculated using the standard thermodynamics of adsorption isotherms. Cordierite is regarded as a mixture of Mg2Al4Si5O18 and H2O. The activity of H2O in the cordierite is evaluated relative to an hypothetical standard state extrapolated from infinite H2O dilution, by using measured hydration data. The activity of Mg2Al4Si5O18 in the cordierite is then obtained by integration of the Gibbs-Duhem equation, and the pressure stabilization increment,ΔP, computed by means of the relation: $$\Delta V_s \Delta P \cong - RT\ln a_{MgCd}^{MgCd \cdot nH2O} \left( {\Delta V indepentdent of P and T} \right)$$ . Thus, one may contour theP-T plane in isopleths of nH2O=constant within the area of Mg-cordierite stability allowed by the hydration data for $$P_{H_2 O} = P_{total} $$ . The present model indicates greater stabilization of cordierite by H2O than the model of Newton and Wood (1979) and the calculated curve for metastable breakdown of hydrous MgCd is consistent with experimental data on cordierite breakdown at $$P_{H_2 O} = P_{total} $$ . Mg/(Mg+Fe) isopleths have been derived for cordierites of varying nH2O in the SiO2-Al2O3-MgO-FeO-H2O system using the additional assumptions that (Fe, Mg) cordierite and (Fe, Mg) garnet behave as ideal solutions, and that typical values of the distribution coefficient of Fe and Mg between coexisting garnet and cordierite observed in natural parageneses can be applied to the calculations. The calculated stable breakdown curve of Fe-cordierite under conditions of $$P_{H_2 O} = P_{total} $$ to almandine, sillimanite, quartz and vapor has a positive slope (dP/dT) apparently in contrast to the experimental negative slope. This may be explained by hydration kinetics, which could have allowed systematic breakdown of cordierites of metastable hydration states in the experiments. The bivariant Cd-Ga fields calibrated from the present model are, potentially, good petrogenetic indicators, as, given the iron-magnesium ratio of garnet and cordierite and the hydration number of cordierite, the temperature, pressure and water fugacity are uniquely determined. As this geothermobarometer is in part based on the water content of cordierite, it can be used only if there is some assurance that the actual hydration is inherited from high-grade metamorphic conditions. Such conditions could be realised if the slope of unloading-cooling retrograde metamorphism is more or less parallel to a cordierite isohydron.

The demand for military expenditures: An international comparison

Abstract: Earlier studies have explained inter-country variations in the share of GNP devoted to military expenditures by international spillovers and by differences in the threat of attack related to relative incomes. In this paper, we use the theory of public choice to explain these differences. We attempt to measure the importance of both international spillovers and relative incomes, along with two other factors: the tax-price elasticity of demand and economies of scale in the consumption of security. We find that international spillovers are significant and positive, that the income elasticity of demand is greater than unity, that the tax-price elasticity of demand explains part of observed inter-country differences, and that there are considerable economies of scale in the consumption of military spending. Finally, between 1960 and 1975, there was apparently a substantial increase in the value which each country derived from a dollar of military spending by its allies. This phenomenon, which seems related to the increased importance of deterrent weapons, has tended to induce individual alliance members to reduce the share of their national income devoted to defense.

Stromal myofibroblasts in primary invasive and metastatic carcinomas. A combined immunological, light and electron microscopic study.

Abstract: A series of 23 primary invasive and 7 metastatic carcinomas was examined by light microscopy (LM), transmission electron microscopy (TEM) and immunofluorescence (IF), the latter employing an anti-actin antibody. The results were correlated with macroscopic features such as retraction and consistency. Stromal cells rich in actin, readily identified by IF in firm and retracted carcinomas, were rare or absent in neoplasms lacking these features. TEM established the myofibroblastic nature of these stromal cells. Alternate sections (LM, IF) of each neoplasm demonstrated that myofibroblasts were more numerous in “young” mesenchymal stroma than in densely sclerotic areas. The connective tissue adjacent to intraductal mammary carcinoma lacked myofibroblasts, suggesting that epithelial stromal invasion is required to evoke a myofibroblastic stromal response. Myofibroblasts which possess synthetic (type III collagen) and contractile properties may well contribute to the firm consistency and retraction which characterize many carcinomas. The induction of myofibroblasts might represent an important host stromal response directed toward containment of invasive and/or metastatic carcinoma. This response may be especially important in neoplasms with weak antigenicity and/or slow doubling times.

\(\dot VO_2 \) peak during free swimming using the backward extrapolation of the O2 recovery curve

Abstract: The purpose of this study was to evaluate the accuracy and feasibility of estimating oxygen consumption (\(\dot VO_2 \)) during maximal swimming by using the backward extrapolation (BE) of the\(\dot VO_2 \) recovery curve to time zero. Two series of experiments were conducted. In the first, the validity of the BE method was ascertained by comparing the\(\dot VO_2 \) peak values obtained during free swimming (Douglas bag technique) with those estimated by the BE method during recovery after the same tests. These results were also compared with\(\dot VO_2 \) peak measured during uphill treatmill running.\(\dot VO_2 \) peak measured during maximal free swimming and estimated by the BE method during the recovery period of that test, were not significantly different. No significant difference was found between\(\dot VO_2 \) peak uphill treadmill running and free swimming. In the second series of experiments,\(\dot VO_2 \) peak was measured in each of 28 swimmers during uphill running (conventional method) and during unimpeded swimming using the BE method. The mean value was significantly higher during swimming (\(\overline X \)3.37) than during running (\(\overline X \)3.23). Seventy-five percent of the subjects had higher\(\dot VO_2 \) peak during swimming. The swimming speed during maximal swimming effort was 10% higher when the BE method was used then when the same subjects were tested by the conventional Douglas bag technique. The BE method is a reliable and valid way to measure\(\dot VO_2 \) peak in maximal swimming and allows the swimmer to use his specifically trained musculature fully.

The evolving trna molecul

Abstract: The study of tRNA molecular evolution is crucial to understanding the origin and establishment of the genetic code as well as the differentiation and refinement of the machinery of protein synthesis in prokaryotes, eukaryotes, organelles, and phage systems. The small size of the molecule and its critical involvement in a multiplicity of roles distinguish its study from classical protein molecular evolution with respect to goals and methods. Here, theauthors assessavailable and missingdata, existingand needed methodology, and the impact of tRNA studies on current theories both of genetic code evolution and of the evolution of species. They analyze mutational “hot spots”, the role of base modification, synthetase recognition, codon-anticodon interactions and the status of organelle tRNA.

Pre- and postsynaptic effects of zimelidine and norzimelidine on the serotoninergic system: single cell studies in the rat.

Abstract: The pre- and postsynaptic effects of zimelidine and norzimelidine were studied in adult male Sprague-Dawley rats. The potency of the presynaptic effect was estimated from their ability to depress the rate of firing of serotonin (5-HT)-containing raphe neurons. Chronic administration of tricyclic antidepressant drugs has been shown to sensitize forebrain postsynaptic 5-HT receptors. The effect of zimelidine on these receptors was compared to that of saline and chlorimipramine by assessing the responsiveness of hippocampal pyramidal cells to microiontophoretic applications of 5-HT, norepinephrine (NE) and γ-aminobutyric acid (GABA). Consistent with their known 5-HT reuptake blocking property, acute intravenous administration of zimelidine and norzimelidine depressed the firing rate of 5-HT-containing dorsal raphe neurons. ED50 of zimelidine and norzimelidine were respectively 1.1 mg/kg and 0.8 mg/kg. Chronic administration of zimelidine (5 and 10 mg/kg, q.d. for 14 days) did not modify the responsiveness of hippocampal pyramidal cells to iontophoretic applications of 5-HT, NE and GABA, whereas chlorimipramine (5 mg/kg, q.d. for 14 days) increased selectively their sensitivity to 5-HT. Since the antidepressant efficacy of zimelidine is well documented, it is concluded that sensitization of forebrain postsynaptic 5-HT receptors is not a prerequisite for a drug to exert an antidepressant effect. It is suggested that an enhancement of the 5-HT-mediated synaptic transmission might be the final effect of the various types of antidepressant treatment whether their primary effect is pre- or postsynaptic.

Rank tests for serial dependence

Abstract: A family of linear rank statistics is proposed in order to test the independence of a time series, under the assumption that the random variables involved have symmetric distributions with zero medians, without the standard assumptions of normality or identical distributions. The family considered includes analogues of the sign, Wilcoxon signed-rank and van der Waerden tests for symmetry about zero and tables constructed for these tests remain applicable in the present context. The tests proposed are exact and may be applied to assess serial dependence at lag one or greater. The procedures developed are illustrated by a test of the efficiency of forward exhange rates as predictors of future spot rates during the German hyperinflation.

Distribution of catecholamines and serotonin in the rat cerebral cortex: absolute levels and relative proportions.

Abstract: The rat cerebral cortex was dissected in five regions and analyzed for the catecholamines noradrenaline, adrenaline and dopamine, and for the indoleamine serotonin using sensitive radioenzymatic assay methods with thin-layer-chromatography. The noradrenaline concentration was highest in the ventral cortex, lateral to the hypothalamus, had intermediate values for the prefrontal, frontal and parietal cortical areas and was lowest in the occipital cortex. Dopamine levels were also highest in the cortex lateral to the hypothalamus, and moderate in the prefrontal and frontal cortical areas, with the lowest values measured for the occipital cortex. The ratios dopamine/noradrenaline further support the hypothesis that they are independent transmitters. Traces of adrenaline were measured in all regions examined. The serotonin distribution was found to be non-homogeneous, with the highest values for the prefrontal cortex and ventral cortex lateral to the hypothalamus. The functional significance of these amines and their ratios are discussed in relation to their role as putative modulators of cortical neuronal excitability.

Gene for neuraminidase activity on mouse chromosome 17 near h-2: pleiotropic effects on multiple hydrolases

Abstract: The low activity of liver neuraminidase that is characteristic of mouse strain SM/J is inherited as a single gene on chromosome 17, near the major histocompatibility complex. This gene, neuraminidase-1 (Neu-1), is represented by the low activity allele Neu-1s in SM/J and the high activity allele Neu-1b in C57BL/6J and most other strains. Previously described variations in the posttranslational processing of acid phosphatase, alpha-mannosidase, arylsulfatase-B, and alpha-glucosidase are attributed to pleiotropic effects of this gene.

SEROLOGICAL EVIDENCE OF SOME BOVINE VIRUSES IN THE CARIBOU (Rangifer tarandus caribou) IN QUEBEC

Abstract: The prevalence of antibodies to some bovine viruses of the respiratory and digestive systems were investigated in two caribou herds in Northern Quebec, Canada, in autumn of 1978 in one herd, and 1979 in another herd. The serum neutralization and hemagglutination inhibition techniques were used. Antibody to bovine viral diarrhea was the most prevalent in the two years (69.3% in 1978 and 60.7% in 1979), followed by bovine adenovirus 3 (42.9% and 17.8%), infectious bovine rhinotracheitis virus (39.6% and 14.2%) and coronavirus (13.3% in 1978 only). Antibody to parainfluenzavirus 3 was not detected.

Inter-hemispheric competition during postnatal development

Abstract: Functional asymmetries between the two sides of the brain, a well documented phenomenon in species as different as frog and man1,2, are thought to arise from genetically determined anatomical differences which, at least in humans, may be observed in utero3. Functional asymmetries can, however, be reversed after damage to one side of the brain4. Here we report that rearing of kittens with the optic chiasm sectioned and one eyelid sutured during postnatal development results in a functional asymmetry in the corpus callosum, a bidirectional pathway which inter-connects the visual cortices on the two sides of the brain. Visual input originating on the side of the brain ipsilateral to the sutured eye loses the ability to influence cells on the other side of the brain. Conversely, visual input originating on the side of the brain ipsilateral to the exposed eye markedly increases its influence in the other hemisphere.