Showing papers by "University of Ottawa published in 1969"
TL;DR: The aim of this study was to determine the effect of varying concentrations of acetylcholine on the vasoconstriction of the perfused mesenteric arteries of the rat caused by stimulation of their sympathetic postganglionic nerves.
Abstract: The aim of this study was to determine the effect of varying concentrations of acetylcholine on the vasoconstriction of the perfused mesenteric arteries of the rat caused by stimulation of their sympathetic postganglionic nerves. Perfusion was carried out with a peristaltic pump, and the constriction caused by stimulation was measured by the rise of pressure in the cannula tied in the artery. Two effects were found. At rates of stimulation between 2 and 8/sec, acetylcholine added to the perfusion fluid in very low concentrations (50 pg/ml) caused an increase in the vasoconstriction. An increase was also caused by adding a concentration of 2 ng/ml for 15 seconds. If, however, this or a greater concentration was added for a longer time, it had the opposite effect and the vasoconstriction was greatly reduced or blocked. This reduction or block was not due in the main to a reduction or block of the vasoconstrictor action of norepinephrine. Block of response to stimulation was also produced by guanethidine. The block produced by acetylcholine resembled the block produced by guanethidine in two respects. The block was removed by raising the calcium concentration, and it was also removed by adding d -amphetamine to the perfusion fluid. The block produced by a given concentration of acetylcholine was abolished by a much higher concentration of atropine or hyoscine.
376 citations
TL;DR: It is concluded that hydrocortisone enhances the responses of vascular smooth muscle to epinephrine and norepinephrine by inhibiting a major enzymatic pathway for the inactivation of these amines.
Abstract: Hydrocortisone potentiated responses of rabbit aortic strips to catecholamines (epinephrine, norepinephrine, nordefrin, isoproterenol) but not to amines lacking the catechol nucleus (phenylephrine, synephrine, methoxamine). Contractions in response to epinephrine were increased much more than those to norepinephrine. Neither the presence of cocaine nor pretreatment of the rabbits with reserpine impaired the potentiating action of hydrocortisone. Experiments with the oil immersion technique (to prevent loss of amine by diffusion from the tissue) demonstrated that hydrocortisone reduced the rate at which aortic strips inactivated epinephrine, apparently by inhibiting catechol-O-methyl transferase (COMT). Known inhibitors of COMT (U-0521, tropolone, pyrogallol) potentiated responses of aortic strips to epinephrine much more than to norepinephrine and also enhanced responses to isoproterenol and nordefrin to the same extent as did hydrocortisone. Known inhibitors of COMT consistently abolished the enhancing effects of hydrocortisone without materially interfering with potentiation produced by cocaine which is mediated through an independent mechanism unrelated to amine inactivation. Hydrocortisone also abolished the enhancing effects of known COMT inhibitors. It is concluded that hydrocortisone enhances the responses of vascular smooth muscle to epinephrine and norepinephrine by inhibiting a major enzymatic pathway for the inactivation of these amines.
209 citations
TL;DR: Cytoarchitectonic and myeloarchitectonics of the cerebral cortex were introduced around the turn of the century as a method of outlining cortical areas with the particular scope of localizing functional units and, together with the neurophysiological approach, such functionally and architectonically determined cortical areas could be’ demonstrated throughout most of the mammalian orders.
Abstract: Cytoarchitectonics and myeloarchitectonics of the cerebral cortex were introduced around the turn of the century as a method of outlining cortical areas with the particular scope of localizing functional units. Together with the neurophysiological approach, such functionally and architectonically determined cortical areas could be’ demonstrated throughout most of the mammalian orders. In particular, sensory receiving areas for vision, audition, and tactility and, contiguous with the latter, effector motor areas could be outlined. From the point of view of the architectonicists, particular terms were coined regarding the structure of the neocortex on the one hand and of the older cortices on the other. The neocortex, insofar as it passes through a 6-laminated period during fetal life, is referred to as isogenetic cortex, short isocortex. The older cortices-the medial archicortex (hippocampus formation of mammals) and the lateral paleocortex (olfactory cortex proper) which exhibit very peculiar characteristics in addition to limited lamination are classified as allogenetic cortex, short allocortex. However, two particular intermediate structural steps are encountered, the first going out from allocortex to isocortex, referred to as periallocortex, and the second intercalated between the latter and the mature isocortex, referred to as proisocortex. Periallocortex ( pAll) and proisocortex (Pro) mediate structurally between the extreme types of allocortex and isocortex (FIGURE 1 ) . Both the architectonic and the electrophysiological studies were first made in monkey and in man (Brodmann, 1909; Campbell, 1905; Foerster, 1936; C. & 0. Vogt, 1919) and subsequently in many other mammals. For example, the central region of higher primates comprises the precentral motor cortex, an agranular type of cortex with the largest pyramidal cells of layer V, and the postcentral somatic sensory cortex, a highly granular type of cortex with the highest degree of granularization in area 3b. For this hypergranular type, von Economo (1925) introduced the term koniocortex, which means powder cortex, since not only granular layers I1 and IV are well elaborated, but the whole outer main stratum of cell layers 11,111, and IV appears enriched with granular cells and stands out by its cell density against a light V and dense VI of the inner main stratum. It is this hypergranular type which, with specific modifications, also forms the central areas of the auditory and visual regions. The agranular motor cortex and the eugranular sensory cortex meet in the depth of the deep central sulcus of higher primates corresponding to a general rule, which we have elaborated in a series of mammals, that the majority of the bottoms of sulci and even fissurets form the limit of architectonic areas.? (Sanides, 1962; Sanides & Krishnamurti, 1967; Sanides & Hoffmann, in press.) The central sulcus of higher primates has, moreover, a decisive meaning for
207 citations
TL;DR: Preliminary support for the hypothesis that the average evoked potential (AEP) recorded from the human scalp may reflect the neural correlates of higher mental activity or information processing by the brain is provided.
Abstract: PREVIOUS attempts to correlate electrophysiological variables with behavioural indices of intelligence have been inconclusive1. Recent findings suggest that the average evoked potential (AEP) recorded from the human scalp may reflect the neural correlates of higher mental activity or information processing by the brain2. The speed of this process, measured by the latency of sequential AEP components, could be the biological substrate of individual differences in behavioural intelligence. AEP latency data from cretinized rats3, hypothyroid patients4, aribo-flavinotic children5 and humans with differential intelligence6 provide preliminary support for this hypothesis.
178 citations
TL;DR: It is concluded that 17β‐oestradiol, progesterone and desoxycorticosterone potentiate responses to catecholamines in aortic strips by inhibiting a major mechanism for their inactivation.
Abstract: 1. Responses to catecholamines (adrenaline, noradrenaline, nordefrine) were enhanced by 17β-oestradiol, progesterone and desoxycorticosterone in untreated and reserpine pretreated aortic strips. Responses to tyramine, believed mediated via endogenous catecholamines, were enhanced only in untreated strips.
2. Responses to sympathomimetic amines lacking the catechol nucleus (phenylephrine, synephrine, methoxamine) were potentiated inconsistently by the steroids and reserpine pretreatment reduced markedly the frequency of potentiated responses.
3. Known inhibitors of catechol-O-methyl transferase (tropolone, U-0521, pyrogallol) potentiated responses to catecholamines and abolished the enhancing effects of the steroids—when the steroids were given first, there was no further increase in response to catecholamines on adding inhibitors of catechol-O-methyl transferase.
4. Experiments with the oil-immersion technique, to eliminate diffusion of drug from the tissue, indicated that 17β-oestradiol, progesterone and desoxycorticosterone decreased the rate at which aortic strips inactivated adrenaline by O-methylation.
5. It is concluded that 17β-oestradiol, progesterone and desoxycorticosterone potentiate responses to catecholamines in aortic strips by inhibiting a major mechanism for their inactivation.
132 citations
TL;DR: In this article, chemical and mineralogical analyses of manganese nodules from a large number of widely spaced localities in the Pacific and Indian Oceans have shown that their mineralogy and chemical composition varies both areally and with depth of formation.
119 citations
TL;DR: The distribution of crystals and crystal boundaries in a thin-section of a pyroxene-scapolite-sphene granulite from Quebec is examined in detail in this paper.
103 citations
TL;DR: Observations support the hypothesis that the adrenergic α-receptor may bear analogy to the “carboxyl” serine hydrolases.
82 citations
TL;DR: It is proposed that by coiling/decoiling and folding/unfolding of the unit-filaments, shifts in physicochemical properties of the axoplasm are maintained.
Abstract: High-resolution electron microscopy is integrated with physicochemical methods in order to investigate the following preparations of the giant nerve fibers of the squid ( Loligo pealii L. ): ( 1 ) Thin sections of fibers fixed in four different fixatives; ( 2 ) fresh axoplasm stained negatively in solutions of different pH and composition; ( 3 ) chemically isolated threadlike elements of the axoplasm. A continuous, three-dimensional network can be identified in all these preparations of the axoplasm. The network is composed of coiled or looped unit-filaments ∼30 A wide. The unit-filaments are intercoiled in strands ∼ 70–250 A wide. The strands are oriented longitudinally in the axoplasm, often having a sinuous course and cross-associations. Microtubules are surrounded by intercoiled unit-filaments and filamentous strands. Calcium ions cause loosening and disintegration of the network configuration. UO 2 ++ ions of a 1% uranyl acetate solution at pH 4.4 display a specific affinity for filamentous protein structures of the squid giant nerve fiber axoplasm, segregating the filamentous elements of the axoplasm in a coiled, threadlike preparation. The uranyl ions combine probably with the carboxyl groups of the main amino acids of the protein—glutamic and aspartic acids. It is proposed that by coiling/decoiling and folding/unfolding of the unit-filaments, shifts in physicochemical properties of the axoplasm are maintained.
74 citations
TL;DR: In this article, a potentiostatic anodic step charging method was used to study the involvement of surface oxide species in the oxygenevolution reaction at nickel electrodes in alkaline solution.
71 citations
TL;DR: A purification procedure for yeast aspartate transcarbamylase (ATCase) resulted in co-purification of the carbamoyl phosphate synthetase (CPSase) of the pyrimidine pathway; indeed, the CPSase specific activity rose by a considerably higher factor during the purification than did the ATCase.
TL;DR: In this paper, the average abundances of some elements in Pacific clay sediments were calculated using new analytical data on twenty-six Pacific pelagic clay samples, together with previously published analyses.
TL;DR: In this paper, the relation between reaction rate and potential for electrochemical surface processes occurring under potentiodynamic control (linear potential-time programme) has been investigated with particular reference to the behavior of thin surface oxide films on noble metals.
Abstract: The relation between reaction rate and potential (or time) for electrochemical surface processes occurring under potentiodynamic control (linear potential-time programme) has been investigated with particular reference to the behaviour of thin surface oxide films on noble metals. The kinetics of processes involving adsorbed electroactive species are treated for several model cases; the rate equations are developed for mechanisms involving various reaction orders or for processes involving adsorbed reactant interactions and surface heterogeneity effects. By examination of the dependence of the reaction rate (current) with time and the effect of potential scan rate, v , on the maximum reaction velocity and the potential at which it occurs, the models may be distinguished. In this manner, the interdependence of v and the reaction velocity constants k a and k c for the anodic oxidation and the cathodic reduction processes respectively, can be quantitatively established. The relation between quasi-equilibrium situations where the reverse reaction is significant and irreversible situations where it is not can be demonstrated. Heterogeneity terms introduced into the kinetic relations express deviations from Langmuir adsorption behaviour and may be an intrinsic property of the substrate surface or a property of the adsorbed reactant (induced heterogeneity). Applications of the treatment are made to reduction of surface oxide species at the noble metals and the significance of hysteresis and time effects in the processes of electrochemical formation and reduction of surface oxide at platinum, rhodium, iridium and palladium is investigated.
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TL;DR: These nitro sugars command great interest as synthetic intermediates for rare and less readily accessible compounds of known or potential biological or medicinal importance, especially in the realm of amino sugars.
Abstract: Publisher Summary The development of the chemistry of nitro sugars, which is essentially based on the syntheses and transformations of nitro sugar derivatives is well established. The chemistry of nitro sugars has experienced considerable expansion in various directions. This chapter describes work that has appeared lately. It considers deoxynitro carbohydrates only. Nitromethane is considered the principal vehicle for introducing the nitro group into sugars and cyclitols. The position of the nitro group in the sugar chain and not its mode of introduction are adopted as the principle of ordering. It is observed that only one nitro sugar has been encountered in nature till date, which is obtained as a hydrolytic fragment from everninomicin antibiotics and named “evernitrose.” These nitro sugars command great interest as synthetic intermediates for rare and less readily accessible compounds of known or potential biological or medicinal importance, especially in the realm of amino sugars.
TL;DR: It is concluded that the mechanism of action of verapamil on the sinus and AV nodes involve a direct cardiac effect as well as an antagonism of vagal mechanisms.
TL;DR: In this article, a kinetic theory of self-inhibition effects is presented in general terms for various supposed oxidation states of the surface region of the electrode interphase, and a comparison of the two types of surface oxides is presented.
TL;DR: In this article, the mass spectra of maleic acid, itaconic, mesaconic and phthalic acids have been examined and fragmentation mechanisms are proposed for these compounds, including the molecular ion of the cis acid fragments via H atom transfer from one carboxyl group to the other followed by loss of CO2.
Abstract: The mass spectra of maleic acid, maleic acid-2,3-d, fumaric acid and fumaric acid-2,3-d have been examined and fragmentation mechanisms are proposed for these compounds. The molecular ion of the cis-acid fragments via H atom transfer from one carboxyl group to the other followed by loss of CO2. The trans acid does not fragment significantly by this route and the former effect may be characteristic of molecules containing two carboxyl groups cis-oriented to each other. This hypothesis was successfully tested by examining the mass spectra of citraconic, itaconic and phthalic acids. Itaconic and mesaconic acids show some of the fragmentation characteristics of fumaric acid.
TL;DR: Results are consistent with the hypothesis that the natural resorption of medullary bone during egg-shell formation in hens and following the withdrawal of oestrogen in cocks is induced by parathyroid hormone.
Abstract: The medullary bone in the femora of laying hens and of oestrogen-treated cocks has been examined by histological, histochemical, alpharadiographic and microroentgenographic techniques while undergoing both natural resorption and resorption induced by injection of parathyroid extract. In the hens, natural resorption was brought about by egg-shell formation and in the cocks by withdrawal of oestrogen. Natural resorption was accompained by increasing basophilia, azurophilia and metachromasia and by decreasing alpharadiographic and microradiographic density of the trabeculae of the medullary bone. These changes were observed initially in the central region (towards the marrow cavity) and subsequently in the peripheral regions also, where the number of osteocytes per unit area of bone was less. Parathyroid extract enhanced all these effects. It appears that resorption of medullary bone was brought about by osteocytic osteolysis and by osteoclasis, but it was not possible to determine whether both processes occurred concurrently or whether the osteoclasts attacked the trabeculae only after they had been partially degraded by osteolysis. These results are consistent with the hypothesis that the natural resorption of medullary bone during egg-shell formation in hens and following the withdrawal of oestrogen in cocks is induced by parathyroid hormone.
TL;DR: In this article, a particle identification method, in which an experimental range-energy relation is stored in the computer memory, was proposed, which is relatively fast and potentially more selective than analogue devices.
TL;DR: A differential staining of the nuclear subgroups of the amygdala was observed following the intravital injection of dithizone and sections prepared by the sulphide silver technique of Timm and it is suggested that the histochemical specificity of the stain is related to one or more of the afferent systems to the amygdala.
Abstract: In material obtained following the intravital injection of dithizone and sections prepared by the sulphide silver technique of Timm, a differential staining of the nuclear subgroups of the amygdala was observed. With both stains, the areas of maximum density were as follows: 1. the lateral border of the lateral nucleus; 2. the ventromedial part of the lateral nucleus; 3. an area in the parvocellular part of the basal nucleus; 4. a round area laterally in the central nucleus; 5. the cortical nucleus. It is suggested that the histochemical specificity of the stain is related to one or more of the afferent systems to the amygdala. The areas projecting to the amygdaloid complex are considered briefly and the possibility that the stain may be associated with the terminals of fibres arising in the pyriform cortex is discussed.
TL;DR: Female Sprague-Dawley rats weighing approximately 70 gm.
Abstract: Female Sprague-Dawley rats weighing approximately 70 gm. were used. The young animal is much more susceptible to the effects of Mg depletion because of increased growth requirements and smaller Mg stores. Experimental groups were fed a standardized, Mg-deficient diet containing less than 1 mg of Mg per 100 g. (General Biochemicals, Chagrin Falls, Ohio) and de-ionized, doubly-distilled drinking water ad libitum. A list of the components of this diet is published elsewhere.g One control group received the above diet supplemented with 200300 mg of Mg chloride per 100 gm, while a second got Purina chow containing 200 mg of Mg per 100 g. Animals were killed at 3, 5, 7, 10, and 14 days and at weekly intervals thereafter up to 60 days. Portions of anterior thigh muscles were fixed in neutral formalin and embedded in paraffin for light microscopy. Sections were stained routinely with hematoxylin and eosin (H&E) , periodic acid-Schiff reaction (PAS), and phosphotungstic acid-hematoxylin (PTAH) . The von Kossa technique was used in cases of calcification. In selected rats, cryostat sections of freshly frozen muscle were stained with Oil Red 0 to demonstrate lipid.
TL;DR: In this article, factors affecting the Cardiotoxic potential of Cobalt are discussed, and the authors propose a method to identify the most important factors that affect the potential of cobalt.
Abstract: (1969). Factors Affecting the Cardiotoxic Potential of Cobalt. Clinical Toxicology: Vol. 2, No. 3, pp. 257-271.
TL;DR: The EEL 140 atomic absorption spectrophotometer, when operated in the manner suggested in the study, is technically easy to use, and gives precise, sensitive, and reproducible results for magnesium in a variety of biologic material.
Abstract: The use of the EEL 140 atomic absorption spectrophotometer for the determination of magnesium in plasma, skeletal muscle, and bone is described together with an examination of the pattern of chemical interference in each type of sample. The sampling procedure and preparation of each kind of sample for analysis is detailed, and recovery studies on plasma bone and muscle are presented. The mean value for plasma magnesium in 42 normal men and women was 2.16 mg/100 ml ± SD of 0.08. For 30 male Wistar strain rats, the plasma value was 2.10 mg/100 ml ± SD of 0.18. In 15 normal postmortem human muscle samples, the mean magnesium content was found to be 93 mg/100 g of dry muscle, the series range being between 83 and 101 mg/100 g. The comparable value in 49 male rats was 125 mg/100 g dry weight ± SD 1.8. Bone magnesium in femur diaphysis of 20 male rats (average weight 200 g) was 563 mg/100 g dry weight ± SD 12.7. It is concluded that this instrument, when operated in the manner suggested in our study, is technically easy to use, and gives precise, sensitive, and reproducible results for magnesium in a variety of biologic material.
TL;DR: It was concluded that differential rearing has measurable effects on certain aspects of the albino rat's behavior and physiology.
Abstract: In two related experiments, albino rats were split into enriched and impoverished groups at weaning, and were reared for two months in differential environments, one group in a large cage containing toys, the other in individual cages. Photic evoked potentials were obtained from all subjects both at weaning and after differential rearing, and mean group latencies were compared. At the end of the experimental period, all subjects were tested on a black-white brightness discrimination. It was found that although the groups did not differ in evoked potential latency at weaning, after differential rearing there were significant latency differences. The enriched group developed shorter latencies than the impoverished group. At the end of the experiment, the enriched group obtained superior scores on a brightness discrimination test. It was concluded that differential rearing has measurable effects on certain aspects of the albino rat's behavior and physiology.
TL;DR: In this paper, a forced-recirculation apparatus was employed for the determinations of liquid-liquid-vapor equilibrium compositions for the nitrogen-ethane binary and nitrogen-methane-thane ternary systems from −255° to −219.8°F and at pressures up to 591 psia.
Abstract: Liquid-liquid-vapor equilibrium compositions were measured for the nitrogen-ethane binary and the nitrogen-methane-ethane ternary systems from –255° to –219.8°F and at pressures up to 591 psia. A forced-recirculation apparatus was employed for the determinations. Experimental results were interpreted and correlated. Optimum operating temperature for nitrogen separation has been suggested.
On a determine les compositions d'equilibre entre liquide et melange de liquide et vapeur dans le cas du systeme binaire azote-ethane et du systeme ternaire azotemethane-ethane a des temperatures variant entre –255° et –219.8°F et des pressions absolues s'elevant jusqu'a 591 livres au pouce carre. On a utilise un appareil a re-circulation forcee pour les dites determinations. On a interprete les resultats experimentaux et etabli une correlation entre eux. On a propose une temperature optimale d'operation pour la separation de l'azote.
TL;DR: In this paper, the kinetics of methanol oxidation were studied over manganese dioxide-molybdenum trioxide catalyst in an integral flow reactor between 250 and 460 °C, at space velocities of 9.6 × 103 to 8.4 × 104 hr−1.
TL;DR: In this article, correlation coefficients for various pairs of elements in pelagic deposits demonstrate the presence of several inter-element associations, mainly due to the partition of elements between the different mineral phases present in the deposits, and, in the case of nodules, from variations in their depth of formation.
TL;DR: In this paper, a method for calculating the charge associated with deposition of adsorbed intermediates at an electrode surface is derived kinetically for the case of current/time transients arising from a potential step when the steady-state rate of the over-all process is changed as well as the coverage by species involved in that process.
TL;DR: A comparison with beer drinkers' cardiomyopathy was made by as discussed by the authors. But the authors did not consider the effects of alcohol consumption on the pathology of experimentally induced Cobalt Cardiomyopathies.
Abstract: (1969). The Pathology of Experimentally Induced Cobalt Cardiomyopathies. A Comparison with Beer Drinkers' Cardiomyopathy. Clinical Toxicology: Vol. 2, No. 3, pp. 273-287.
TL;DR: Evidence was provided that the main constituents of the monoconjugate fraction in this experiment were monosulphates of estradiols and that the usual suspects of the diconjugates as well as monconjugates of the phenolic steroids were disulphate of est radiols.