Showing papers by "University of British Columbia published in 1971"
TL;DR: Since the oral hygiene measures markedly reduced the sulphur content of mouth air, it is concluded that the determined sulphur compounds are produced by a putrefactive process occurring within the oral cavity.
345 citations
TL;DR: The authors measured the contents (μmol/g wet wt.) of 35 free amino acids and related compounds in 12 different regions of each of five human brains and found marked and consistent differences in the regional distribution of the following eight compounds: γ-aminobutyric acid, homocarnosine, glutamic acid, aspartic acid, taurine, cystathionine, glycerophosphoethanolamine, and phosphoETHanolamine.
Abstract: — Contents (μmol/g wet wt.) of 35 free amino acids and related compounds were measured in 12 different regions of each of five human brains. Specimens were obtained at autopsy from patients who died suddenly without previous brain disease. These data may serve for later comparison with contents of amino compounds in similar regions of the brains of patients dying with various neurological or psychiatric disorders.
There were marked and consistent differences in the regional distribution of the following eight compounds: γ-aminobutyric acid, homocarnosine, glutamic acid, aspartic acid, taurine, cystathionine, glycerophosphoethanolamine, and phosphoethanolamine. These differences suggest that some of these compounds may have special physiological roles, including the possible mediation of synaptic transmission.
Human brain contains two previously unreported compounds, the mixed disulphide of cysteine and glutathione and α-(γ-aminobutyryl)-lysine. The latter dipeptide occurs in much higher concentrations in human brain than in the brains of lower mammals.
292 citations
273 citations
TL;DR: It is proposed that adult poikilotherms may undergo a considerable degree of “biochemical restructuring” on a seasonal basis, and the factors which control this “restructuring,” and the rates at which the process occurs at high and low temperatures are topics for future investigation.
Abstract: SYNOPSIS. Biochemical adaptation to environmental parameters such as temperature appears to involve two distinct types of changes in the organism's chemistry. On the one hand, the quantities of certain molecular species present in the cells may change. Alternatively, the actual types of molecules present may vary. Rainbow trout ( Salmo gairdneri ) acclimated to warm and cold temperatures exhibit a striking example of this latter type of adaptation. For all enzymes we have examined in this species, distinct “warm” and “cold” isozymes are present. The isozymes found in warmacclimated (18°C) trout function well only at temperatures above 10–12°C. The isozymes present in cold-acclimated (4°C) trout function optimally at 2-5°C, temperatures this species normally encounters in winter. These data, plus information on comparable changes in membrane lipids, lead us to propose that adult poikilotherms may undergo a considerable degree of “biochemical restructuring” on a seasonal basis. The factors which control this “restructuring,” and the rates at which the process occurs at high and low temperatures, are topics for future investigation.
250 citations
TL;DR: The frequency of left-handedness is greater in males and in twin births, both of which are also associated with greater birth and infant mortality and, in the case of males, a higher rate of spontaneous abortion, and the pre-natal and peri-natal periods seem to be more stressful for these groups.
Abstract: IN spite of much speculation on the matter, the aetiology of left-handedness remains elusive. Investigators have considered heredity, neurological pathology, imitation and negative personality, but the evidence in support of any particular hypothesis is inconclusive. There are, however, some suggestive facts. The frequency of left-handedness is greater in males and in twin births, both of which are also associated with greater birth and infant mortality and, in the case of males, a higher rate of spontaneous abortion. The pre-natal and peri-natal periods seem to be more stressful for these groups. Left-handedness is also associated with language disorders such as stuttering, dyslexia, and mental retardation, conditions where central nervous system pathology may be implicated1. This suggests that the incidence of left-handedness might be correlated with stressful pre-natal and birth conditions. Such difficulties are most characteristic of primiparous births (longer labour and more use of instruments) and births to older mothers. Thus high risk birth orders would be the first born and the late-born (defined here as fourth or later birth).
217 citations
TL;DR: The sharp decrease in caudate tyrosine hydroxylase with age may be significant in behavioral and drug-tolerance changes in senility.
197 citations
TL;DR: In this paper, the authors describe results of measurements of the fluxes of momentum, moisture and sensible heat by both the eddy correlation and dissipation techniques on R/V Flip during BOMEX (Barbados Oceanographic and Meteorological Experiment) and during a pre-BOMEX trial cruise near San Diego in February 1969.
Abstract: This paper describes results of measurements of the fluxes of momentum, moisture and sensible heat by both the eddy correlation and “dissipation” techniques. The data were collected on the R/V Flip during BOMEX (Barbados Oceanographic and Meteorological Experiment) and during a pre-BOMEX trial cruise near San Diego in February 1969. The results are mainly based on data collected by personnel from Oregon State University and the University of British Columbia. We are grateful to the University of Washington personnel who have made their data and results available to us to check some of our results and allowed us to use their temperature fluctuation data from the San Diego cruise when our equipment failed to provide such data. The methods of determining the fluxes are discussed. The instrumentation and methods of data analysis are described. The effects of Flip's interference on the flow are described and the method of removing the interference from the results is given. The spectra of the three co...
192 citations
TL;DR: Values found in biopsies of human brain specimens were frozen in liquid nitrogen within 10 sec of their removal at neurosurgery, so the values found should approximate those which occur in living brain.
Abstract: — Contents (μmol/g wet wt.) of 35 free amino acids and related compounds were measured in biopsies of human brain from ten patients. Brain specimens were frozen in liquid nitrogen within 10 sec of their removal at neurosurgery; thus, the values found should approximate those which occur in living brain.
Levels in free pools of biopsied cerebral cortex of most of the amino acids that are constituents of proteins were only 20-50 per cent of those found in autopsied cortex. The content of cystine and ethanolamine was much lower in biopsied than in autopsied cortex. Concentrations of GABA in biopsied cortex were only 20 per cent as high as those found in autopsied cortex, and levels of γ-aminobutyryl dipeptides were also significantly lower in biopsied cortex. Amounts of cystathionine in biopsied cortex varied markedly, but averaged much higher than in autopsied cortex; a single biopsy specimen of cerebellar grey matter had a cystathionine content 36-fold greater than the mean found in autopsied cerebellum.
Appreciable variability in contents among cortical biopsies was found for glycerophosphoethanolamine, phosphoethanolamine, ethanolamine, taurine, aspartic acid, glutamic acid, glutamine, and GABA, as well as for cystathionine. Whether this variability occurred between different subjects, or between different cortical areas, was not clear, although the former possibility was suggested by findings in multiple cortical biopsies from one patient.
191 citations
186 citations
TL;DR: In this paper, the deformation modes operative at various crystal orientations and the effect of purity, temperature, orientation and strain rate, on the work hardening parameters have been investigated.
169 citations
TL;DR: In this paper, it was shown that the important variable controlling the incidence of liquefaction in a given number of cycles in a saturated sand at a particular void ratio is the initial effective stress ratio; the ratio of the peak alternating shear stress to the average effective mean normal stress.
Abstract: Data from cyclic loading simple shear and triaxial tests indicate that the important variable controlling the incidence of liquefaction in a given number of cycles in a saturated sand at a particular void ratio is the initial effective stress ratio; the ratio of the peak alternating shear stress to the initial effective mean normal stress. Contrary to previously published results, equal resistances to liquefaction are obtained in both kinds of tests. This agreement is considered to be due to three things: (1) Representation of the confining pressure in the simple shear test by the mean normal stress in the plane of deformation; (2) the improved model of the simple shear apparatus used; and (3) the use of experimental techniques which insures the development of uniform strains in the simple shear test. The experimental techniques used evolved from a fundamental study of the deformation of samples in the simple shear apparatus.
TL;DR: The data suggest that tyrosine hydroxylase may be produced in a soluble form in the cell bodies of the substantia nigra but become bound as it moves toward the nerve endings in the putamen and caudate nucleus.
Abstract: The activity of tyrosine hydroxylase (EC 1.10.3.1) when assayed under ideal conditions in young human brains, was comparable to that in brains of other species in level of activity and distribution. The highest levels of activity were in the putamen, caudate nucleus and substantia nigra, in keeping with data on other species. The caudate activity in human brain appeared to decrease substantially with increasing age. In both humans and baboons, the enzyme in the neostriatum was particle-bound and inhibited by the 2-amino-4-hydroxy-6,7-dimethyltetrahydropteridine cofactor system. In the substantia nigra it was soluble and stimulated by the 2-amino-4-hydroxy-6,7-dimethyltetrahydropteridine cofactor system. The data suggest that tyrosine hydroxylase may be produced in a soluble form in the cell bodies of the substantia nigra but become bound as it moves toward the nerve endings in the putamen and caudate nucleus. The bound form of the enzyme was unstable but the soluble form exhibited considerable stability.
TL;DR: Steketee's Elasticity Theory of Dislocations is generalized to real Earth models in this article, taking into account self-gravitation, radial variation of elastic properties, density and gravity, initial hydrostatic stress, and the presence of the liquid core.
Abstract: Summary
Steketee's Elasticity Theory of Dislocations is generalized to real Earth models. Taken into account are; (i) self-gravitation, (ii) radial variation of elastic properties, density and gravity, (iii) initial hydrostatic stress, (iv) the presence of the liquid core. Volterra's formula for the displacement field is found to hold in the more general circumstances for slip faults.
The dilemma, previously pointed out by Jeffreys and Vicente, which arises when the Adams and Williamson condition is assumed not to hold everywhere perfectly in the core, is resolved. This result also bears on the theory of Earth tides and tidal loading.
Changes in the inertia tensor are shown to arise only from spheroidal displacement fields of degree zero and two. These fields have virtually no attenuation with distance from the fault. In the one example in which a direct comparison can be made, the present theory gives a factor of 7.5 increase over a mapped half-space theory and a factor of 2.9 increase over the result for a uniform, spherical Earth, in the contribution to secular polar shift and excitation of Chandler wobble. Calculated and observed levels appear now to be in agreement.
TL;DR: In this paper, a complete algorithm for the computer solution of steady-state fluid flows in networks is given, with particular stress placed on fast solution, minimal storage requirements and simplicity of the input data.
Abstract: A complete algorithm for the computer solution of steady-state fluid flows in networks is given. Particular stress is placed on fast solution, minimal storage requirements and simplicity of the input data. Although the Hardy Cross method is the classical method of solution of this type of problem, convergence is slow for large networks. To overcome this problem, the whole network is considered simultaneous, and this produces a large system of non-linear equations. Newton's method is applied, which results in an iterative solution of a system of linear equations. In order to reduce computer storage requirements and to simplify the data input, a number of algorithms from graph theory are involved. The resulting matrix of coefficients associated with the system of linear equations is banded and symmetric for which efficient (in time and memory requirements) methods of solution exist.
TL;DR: In this article, a horizontal and vertical sampling of the atmosphere has been performed to study the form of Montreal's urban heat island, showing that the lowest layers of the urban atmosphere become progressively modified as air moves toward the centre of the city.
Abstract: Horizontal and vertical sampling of the atmosphere has provided new information on the form of Montreal's urban heat island. The horizontal pattern under clear skies with light winds shows a major heat island, with marked gradients at the periphery, and a multicellular inner core. Retarded urban cooling rates in the evening yield a maximum heat-island intensity around midnight. Combined horizontal and vertical temperature surveys show that under conditions of strong rural stability, the lowest layers of the urban atmosphere become progressively modified as air moves toward the centre of the city. The change in the form of the potential temperature profile is in good agreement with Summers' internal boundary-layer hypothesis. In Montreal differing heights of heat and SO2 emission appear to produce more than one internal layer. SO2 observations, and heat input calculations reveal two major emission sources in Montreal; one associated with an industrial complex, and the other with the downtown core.
TL;DR: The crystallization of 1, l'—binaphthyl from its racemic melt is an example of spontaneous generation of optical activity and resolution into enantiomers is determined by chance development, with equal probability, of right- or left-handed crystallites.
Abstract: The crystallization of 1, l9—binaphthyl from its racemic melt is an example of spontaneous generation of optical activity. The distribution of specific rotations in 200 individual samples varied from [α]D = —218 degrees to [α]D = +206 degrees with a mean of +0.14 degree and standard deviation of 86.4 degrees. This resolution into enantiomers is determined by chance development, with equal probability, of right- or left-handed crystallites; it can be controlled and made stereospecific by addition of dissymmetric compounds at low concentrations.
TL;DR: The data suggest the selective deterioration of a GAD containing cellular system in Parkinson disease which involves the substantia nigra and globus pallidus, which is similar to that of accident victims and non-Parkinsonian hospital patients dying with various illnesses.
TL;DR: The results suggest (a) that granule cell-mitral cell inhibition may be GABA-mediated; (b) thatgranule cells receive both excitatory noradrenergic and inhibitory GABA- mediated inputs.
TL;DR: The evidence indicates that at all times in the pathogenesis of spinal cord injury the microvasculature in Zone 2 is capable of perfusion.
Abstract: The pathology of spinal cord injury has been studied in 34 rabbits and 5 dogs with attention focused on the condition of the microvasculature during the evolution of neuronal and axonal degeneration and necrosis. The animals were killed and perfused arterially with colloidal barium from 10 min to 14 days after a controlled spinal injury. Microradiographs of the injured tissues were obtained and compared with corresponding histological sections. Microangiography at 7 to 14 days defines two zones in the injured spinal cord. Zone 1 is located in the posterocentral part of the cord. Capillaries in this region progressively lose their ability to conduct blood and perfusate over the first 4 hours. Degenerative changes in neurons are visible by 1 hour after injury. Necrosis of all elements including capillaries ensues. Zone 2 surrounds Zone 1. Microvascular patterns are normal in Zone 2 although neuronal and axonal degeneration is severe. Pericapillary hemorrhages which occur as early as 10 min after injury in Zone 1 and become progressively larger over the first 4 hours seldom are seen in Zone 2. The evidence indicates that at all times in the pathogenesis of spinal cord injury the microvasculature in Zone 2 is capable of perfusion. Degeneration of neural structures either precedes microvascular breakdown (Zone 1) or occurs in the absence of microvascular disruption (Zone 2). Recovery of damaged neurons and axons depends upon a preserved microcirculation.
TL;DR: Sesquiterpene lactones derived from species of the Composltae family of plants have been reported to cause allergic eczematous contact dermatitis and the presence of a i-methylene group exocyclic to tbe y-lactone appears to be the immunochemical requisite for such dermatitis.
Abstract: —Sesquiterpene lactones derived from species of the Composltae family of plants have been reported to cause allergic eczematous contact dermatitis. The presence of a i-methylene group exocyclic to tbe y-lactone appears to be the immunochemical requisite for such dermatitis. A review was made of some 210 sesquiterpenoid compounds witb respect to the presence of such a group; 132 compounds possessing this group were termed \" potentially allergenic \"; 52 lactones have so far been studied and are listed as \" reported allergenic\" or \" reported non-allergenic\". The plants from which these lactones were derived were listed by genus and species for allergenicity. Such lactones are tbe allergens responsible for allergic contact dermatitis caused by ragweed (Ambrosia), feverfew (Partltenitim), sneezeweed (Hetcttiuni), sagebrush, wormwood, mugwort (Artemisia), boneset (Ettpatoriiini), poverty weed (Franseria), marshelder (/vo), cocklebur (Xanthiutn), burdock (Arctiutti), chamoniile (Aiuhemis), artichoke (Cynara), Gatllardia, and Chrysanthetnum species (tansy, pyrethrum).
TL;DR: It was concluded that the stimulatory effect of F- was due to an increase in Vmax, there being no significant effect on the Km for substrate (MgATP) or on the apparent Ka for Mg++.
TL;DR: Peruvian penguins displayed a wide thermoneutral zone, and thermal conductance was computed as 0·81 kcal/m 2 × °C × hr; compared to values for other species of similar weight compiled from the literature, this suggests adaptation to cool conditions.
TL;DR: In this article, a comparison is made of a lower-order linear model and a high-order non-linear system modelled as a single machine-infinite bus as well as multi-machine systems.
Abstract: The stabilization of power systems with excitation control using speed or power signals has been very well developed,1-6 while the application of optimal control to power system stability study is relatively new.7 Both are based on linear models. In this paper, a comparison is made of these two techniques. Signals derived from a lower order linear model are tested on a high order non-linear system modelled as a single machine-infinite bus as well as multi-machine systems.
TL;DR: In this paper, the authors investigated economic optimal policies for the management of natural resource stocks subject to nonconcave reproduction curves and showed that any optimal policy leads either to a sustained yield or to complete destruction of the resource.
Abstract: Economically optimal policies are investigated for the management of natural resource stocks subject to nonconcave reproduction curves. It is shown that any optimal policy leads either to a sustained yield or to complete destruction of the resource. Criteria are established according to which the optimal policy is destructive. The simplifying assumption is made that net revenue (utility) is proportional to the amount of harvest.
TL;DR: Whether fish can be assumed to be in a steady state at all velocities below the critical velocity and whether it is possible to attribute the differences in performance, during anaemia and hypoxia, to increased metabolic cost of the cardiac and branchial pumps are discussed.
Abstract: 1. A series of increasing water-velocity tests in a water tunnel has been used to investigate the maximum swimming performance of two groups of rainbow trout, one acclimated to high temperature (21-23 °C) and the other to low temperature (8-10 °C). 2. At temperatures close to their acclimation temperatures there was no significant difference between the maximum swimming speeds of the two groups of trout. 3. Exposure to an environmental oxygen tension of half the air-saturation value resulted in a 43 % reduction in maximum swimming performance at low temperature and a 30 % reduction at high temperature compared with normal animals. 4. Reduction in haematocrit to one-half or one-third normal resulted in a 34% reduction in maximum swimming speed at low temperature and a 40% reduction at high temperature compared with control animals (blank injected). 5. The results are discussed in terms of whether fish can be assumed to be in a steady state at all velocities below the critical velocity and whether it is possible to attribute the differences in performance, during anaemia and hypoxia, to increased metabolic cost of the cardiac and branchial pumps.
TL;DR: STARVATION and amphetamine both increase behavioural arousal, and have been postulated to act through adrenergic mechanisms in the brain stem through release of catecholamines from the adrenal medulla and their consequent action on brain stem excitatory areas.
Abstract: STARVATION and amphetamine both increase behavioural arousal, and have been postulated to act through adrenergic mechanisms in the brain stem. Amphetamine is believed to induce psychomotor excitation by releasing brain catecholamines, blocking their re-uptake from the synapse and mildly inhibiting the action of the catabolizing enzyme, monoamine oxidase1–3. The drug also accelerates the turnover of nor-adrenaline in the brain stem reticular formation4. Food deprivation increases electrophysiological arousal in the mesencephalic reticular formation and other areas5 and Dell6 postulated that behavioural arousal induced by starvation resulted from the release of catecholamines from the adrenal medulla and their consequent action on brain stem excitatory areas.
TL;DR: Ventilation volume could be increased nearly sevenfold during moderate, shortterm hypoxia as a result of a large increase in ventilatory stroke volume and a small increase in ventilation rate and as perfusion rate went up cardiac output and oxygen uptake increased.
Abstract: 1. Ventilation volume was measured directly in rainbow trout using a rubber membrane attached to the mouth which separated inspired and expired water and allowed collection of the latter. 2. Mean ventilation volume at 8.6 °C for 18 trout weighing approximately 200 g was 37±1.8 ml/min/fish. Mean ventilation rate and ventilatory stroke volume averaged 74 breaths/min and 0.5 ml/breath respectively. 3. Ventilation volume could be increased nearly sevenfold during moderate, shortterm hypoxia as a result of a large increase in ventilatory stroke volume and a small increase in ventilation rate. 4. The ratio between the flow rates of water and blood through the gills was approximately 10. 5. Percentage utilization of oxygen from inspired water had a mean of 46±1.5% and ranged from 23 to 64%. 6. Artificial perfusion of the gills with water at different flow rates was achieved by tying a tube into the mouth of trout. 7. Perfused fish could not saturate their arterial blood with oxygen at a perfusion rate of 45 ml/min but could do so at rates ranging from 85 to 1200 ml/min. 8. Low arterial tensions at a perfusion rate approximating the mean V·G of fish with oral membranes are probably the result of a poor pattern of water flow over the gills during perfusion. 9. Opercular movements occurred only at perfusion rates below 700 ml/min and increased in frequency as perfusion rate dropped. This ventilatory activity may have resulted from receptors sensitive either to water flow over the gills or to arterial Po2. 10. As perfusion rate went up cardiac output and oxygen uptake increased. These changes were accompanied by a drop in dorsal aortic pressure which reflected vasodilation of the gills and peripheral circulation. This change in the pattern of blood flow through the gills contributed to a 50% increase in oxygen transfer factor across the gills. 11. At the highest perfusion rates there was no apparent impairment of gas exchange even though anatomical deadspace was probably high.
TL;DR: The results support the presence of a previously postulated interneuronal feedback mechanism in brain which can regulate dopamine synthesis and this may function at least in part through an effect on tyrosine hydroxylase activity.
TL;DR: The conjecture was promptly shot down by a member of the audience (R. C. Bose), who produced a counter-example that the conjecture was not true, since Collatz and Sinogowitz had displayed two different trees with 8 nodes having the same characteristic polynomial as discussed by the authors.
Abstract: Introduction At a meeting of the American Mathematical Society, one of us hazarded a conjecture that the characteristic polynomial of the adjacency matrix of a graph characterizes the graph, that is, that two graphs are isomorphic if and only if the characteristic polynomials of their adjacency matrices are the same. The conjecture was promptly shot down by a member of the audience (R. C. Bose), who produced a counter-example. In fact, it was already a matter of public record that the conjecture was not true, since Collatz and Sinogowitz [1] had displayed two different trees with 8 nodes having the same characteristic polynomial. In what follows we give an account of some recent computer investigations of the smallest graphs and digraphs of various kinds whose adjacency matrices have the same characteristic polynomial, in order to illuminate the extent to which the characteristic polynomial can be used to characterize a graph.
TL;DR: Ethanol multiplies miniature end-plate potential frequency independently of calcium ion concentrations and also multiplies calcium-dependent depolarization-evoked quantal release, to the same extent, which implies a final common pathway, requiring little or no calcium, for both kinds of transmitter secretion.
Abstract: Ethanol multiplies miniature end-plate potential frequency independently of calcium ion concentrations and also multiplies calcium-dependent depolarization-evoked quantal release, to the same extent. This result implies a final common pathway, requiring little or no calcium, for both kinds of transmitter secretion. Chlorpromazine and hypertonicity act similarly to ethanol, but also depress depolarization-secretion coupling.