Showing papers by "University of Ottawa published in 1975"
TL;DR: In this article, the authors describe several methods designed to detect pits, peaks, passes, ridges, ravines, and breaks, given an array of sampled, quantized terrain elevations.
439 citations
TL;DR: IV injections of certain doses of d-amphetamine or cocaine, immediately prior to test sessions in which response-contingent saline infusions were delivered, reinstated the rate and pattern of responding observed during sessions inWhich drug was self-administered.
Abstract: Responding was established in squirrel monkeys under a modified progressive ratio schedule of IV d-amphetamine or cocaine self-administration. Substitution of saline for the drug solutions resulted in extinction of the self-administration behavior. IV injections of certain doses of d-amphetamine or cocaine, immediately prior to test sessions in which response-contingent saline infusions were delivered, reinstated the rate and pattern of responding observed during sessions in which drug was self-administered. Presession IV injections of several doses of pentobarbital or chlorpromazine failed to consistently reinstate responding. These results were interpreted in terms of the discriminative control of drug self-administration behavior by the current drug state of the subject.
178 citations
TL;DR: After adding 20 ppm of Hg2+, Pb2+, or Cu2+ to the growth media, 80 ppb or less remained as free cations in the solution, which might suggest that such ions enter bacterial cells as organic complexes, or that bacterial cells can compete successfully with growth media for the bound ions.
Abstract: Ion-specific electrodes were used to study the binding of Hg2+, Pb2+, Cu2+, and Cd2+ ions to widely used bacterial growth media (Nutrient broth, trypticase soy broth, the medium of Foot and Taylor [6] and of Nelsonet al.[12]) and to media components [yeast extract, peptone, tryptone, proteose peptone, and casamino acids (acid hydrolyzed casein)]. Volatilization of Hg2+ from aqueous solutions could be prevented by any of the growth media or their components. All media bound large amounts of Hg2+, Pb2+, and Cu2+, but much less Cd2+. Of the media components, casamino acids showed the most binding activity for all metal ions; the relative affinity of other media components to different ions varied with the cation studied. In general, the Irving-Williams [8] series for cation affinity to organic ligands was followed: Hg2+>Pa2+≫ Cu2+≫ Cd2+. After adding 20 ppm of Hg2+, Pb2+, or Cu2+ (concentrations inhibitory to the growth of most microorganisms) to the growth media, 80 ppb or less remained as free cations in the solution. This might suggest that such ions enter bacterial cells as organic complexes, or that bacterial cells can compete successfully with growth media for the bound ions.
171 citations
161 citations
TL;DR: In this article, some properties of the sample estimator of attributable risk A, defined here as the proportion of all cases of disease which may be attributed to a risk factor, are considered for the case-control study situation.
Abstract: SUMMARY Some properties of the sample estimator of attributable risk A, defined here as the proportion of all cases of disease which may be attributed to a risk factor, are considered for the case-control study situation. It is shown that log (1 -A) may be expressed in terms of the prevalences of the factor in cases and healthy controls, that the bias of the estimator is minimized when 2 is added to the cell frequencies corresponding to nonexposed persons in the usual 2 x 2 contingency table, and that the distribution of I - A is asymptotically log normal. Examples of the calculations, and a discussion of the results, are given for a number of risk factors for childhood leukemia.
126 citations
01 Mar 1975
TL;DR: Several methods are available to differentiate between live and dead cells in suspensions using the dye exclusion test, based on the assumption that certain dyes stain only dead cells while live cells remain unstained when exposed to these substances in suspensions.
Abstract: Several methods are available to differentiate between live and dead cells in suspensions. The more elaborate procedures include the measurement of endogenous respiration (1), reduction of 2,3,5-triphenyltetrazolium chloride (2) and uptake of tritiated thymidine (3,4). The most widely used procedure is the dye exclusion test. This method is based on the assumption that certain dyes, e.g. trypan blue, methylene blue, acridine orange, eosin, nigrosin, safranin, etc. stain only dead cells while live cells remain unstained ("exclude" the dye) when exposed to these substances in suspensions.
117 citations
TL;DR: The results of these examinations seem to indicate that the authors are not dealing with a dystrophic calcification, but with a cell-mediated calcification of a living tissue that resembles an incomplete endochondral ossification.
Abstract: Biopsy specimen from 18 patients suffering from calcifying tendinitis were stained with different histologic and histochemical techniques. The results of these examinations seem to indicate that we are not dealing with a dystrophic calcification, but with a cell-mediated calcification of a living tissue. The process resembles an incomplete endochondral ossification.
103 citations
88 citations
86 citations
TL;DR: In this paper, it was shown that up to four excitonic series in Mo$S 2 can be obtained by photoconductivity, photovoltaic effect and wavelength-modulated reflectivity at temperatures of 300 to 4.2 K and in magnetic fields of up to 70 kG.
Abstract: Optical spectra of Mo${\mathrm{S}}_{2}$ in the excitonic region were obtained by photoconductivity, photovoltaic effect and wavelength-modulated reflectivity at temperatures of 300 to 4.2 K and in magnetic fields of up to 70 kG. Cleaved natural crystals and synthetic crystals studied in both the Faraday and Voigt configurations showed nearly the same characteristics. The results indicate the possibility of up to four excitonic series in Mo${\mathrm{S}}_{2}$ as in other Mo dichalcogenides, and support band-structure calculations predicting flat conduction and valence bands originating from Mo orbitals. A ground-state anomaly of the $A$ exciton is explained by a central cell correction of the type used by Harbeke and Tosatti to explain a similiar anomaly in Pb${\mathrm{I}}_{2}$. The reduced mass of the $A$ exciton is found to be ${\ensuremath{\mu}}^{*}\ensuremath{\simeq}0.4{m}_{0}$, both from the study of the series itself, and from its magneto-optical properties, thus removing a large discrepancy found in previous work.
77 citations
TL;DR: Data suggest that the observed increase of diunsaturated fatty acids in cold-grown cells may perhaps be explained by the increased activity of the oleoyl-CoA desaturase acting at the low temperature.
TL;DR: The polar acetone-soluble lipids of Halobacterium cutirubrum were found to contain neo-bacterioruber in U, bacterioruberin U, monoanhydrobacteriorubein, bis-anhydrobacteriaiorUBin, an isomer of geranylgeraniol (with one internal cis-isoprene residue), 2,3,-di-O-phytanyl-sn-glycerol and two unidentified polar isop
TL;DR: The synaptic patterns on the principal cells of turtle visual cortex are remarkably similar to those found on pyramidal cells of mammalian neocortex.
Abstract: The part of turtle general cortex that receives afferent fibers from the dorsal lateral geniculate nucleus and that shows evoked potentials to light stimuli has been studied with the electron microscope. This cortex consists of an outer molecular layer, a perikaryal layer, and a subcellular layer lying on a row of ependymal cell bodies. Neurons in the perikaryal lamina are characterized by long spine-bearing apical dendrites ascending through the outer molecular layer and short finer basal dendrites in the subcellular zone. Scattered neurons without apical dendrites occur in both the molecular and subcellular zones. Two types of dendritic spines can be distinguished. Some are large, have a complex irregular shape, contain a variety of membranous sacs and mitochondria, and occasionally, a single bundle of microtubules embedded in an electron-dense background opacity. These large spines are the most common postsynaptic element in the outer third of the molecular layer, where they are located on the distal tips of the apical dendrites. Other spines are small, with a simple spherical distal enlargement that contains only electron-dense fuzz. They are the most common post-synaptic element in the lower two-thirds of the molecular layer where they arise from the proximal portion of apical dendrites. Most synaptic contacts are found on the dendritic spines and are of the “round-asymmetrical” type. Not infrequently “flat-symmetrical” synapses are seen coupled to “round-asymmetrical” contacts on individual large spines. The few contacts present on spine-bearing dendritic shafts are of both types. Axo-somatic contacts are mainly of the “flat-symmetrical” variety. Thus the synaptic patterns on the principal cells of turtle visual cortex are remarkably similar to those found on pyramidal cells of mammalian neocortex. In addition, however, axon terminals, dendrites and glial (ependymal) processes were often seen to give rise to membranous pouches containing large vacuoles and invaginating into dendritic shafts or spines. Rarely, axon terminals were seen to form contacts, identical in appearance to synaptic contacts, on cell bodies in the ependymal lining. More frequently, unusual types of membrane differentiations were present at the site of apposition of the membranes of axon terminals and ependymal processes. They are interpreted as functional neuroependymal contacts.
TL;DR: Evidence has been presented that alterations in thyroidal status produce marked changes in the metabolism of several biogenic amines in developing brain, suggesting that a critical period exists in early life during which thyroid hormone must be present to permit normal developmental pattern of central amines.
TL;DR: The transport of heavy metals and their effects on biological systems in natural waters are greatly influenced by their interactions with soluble and insoluble water components1,2,3,4.
Abstract: THE transport of heavy metals (HMs) and their effects on biological systems in natural waters are greatly influenced by their interactions with soluble and insoluble water components1,2.
TL;DR: The fatty acid compositions of the three major phospholipids of Escherichia coli K-12; phosphatidylethanolamine,osphatidylglycerol and cardiolipin were determined during growth in media differing in NaCl concentration.
TL;DR: In this article, a study of the oscillatory spectral distribution of the photovoltaic (PV) effect of a gold-indium phosphide Schottky barrier in magnetic fields of up to 70 kG was made.
Abstract: A study is made of the oscillatory spectral distribution of the photovoltaic (PV) effect of a gold-indium phosphide Schottky barrier in magnetic fields of up to 70 kG. Spectra are obtained for both the direct and wavelength-modulated PV signals, the latter being compared to the wavelength-modulated reflectivity data. The spectra are taken at 4.2 K in the Faraday configuration for both circular polarizations. The transition energies associated with the spectral oscillations are corrected for exciton-binding effects, and are analyzed as Landau levels in terms of the Pidgeon and Brown coupled-bands theory of interband magnetoabsorption. The fit to the data gives a conduction-band effective mass $\frac{{m}_{c}}{{m}_{0}}=0.079\ifmmode\pm\else\textpm\fi{}0.001$ and Luttinger parameters ${\ensuremath{\gamma}}_{1}^{L}=5.15\ifmmode\pm\else\textpm\fi{}0.05$, ${\ensuremath{\gamma}}_{2}^{L}=0.94\ifmmode\pm\else\textpm\fi{}0.03$, and ${\ensuremath{\gamma}}_{3}^{L}=1.62\ifmmode\pm\else\textpm\fi{}0.03$. The direct observation of the split-off valence-band-to-conduction-band transition gives ${\ensuremath{\Delta}}_{0}=0.108\ifmmode\pm\else\textpm\fi{}0.003$ eV and an approximate effective mass of $\frac{{m}_{\mathrm{so}}}{{m}_{0}}=0.21\ifmmode\pm\else\textpm\fi{}0.02$.
TL;DR: This chapter discusses the pharmacological basis of DDT and related chlorinated hydrocarbon insecticides toxicity in mammals, which produces a variety of toxic effects and invariably leads to death.
Abstract: Publisher Summary This chapter discusses the pharmacological basis of DDT and related chlorinated hydrocarbon insecticides toxicity in mammals. In mammals, the administration of acute large doses of DDT and related chlorinated hydrocarbon insecticides produces a variety of toxic effects and invariably leads to death. Methoxychlor, that appears to be replacing DDT in certain countries, exhibits toxicity that is about 30 times less than that seen with DDT. The major routes of DDT metabolism in mammals are (1) oxidation to DDA, (2) dehydrochlorination to DDE, and (3) reductive dechlorination to DDD. In vertebrates, the major metabolite of DDT in feces and urine is DDA. Of DDT-derived, ether-soluble material in the rat bile, DDT constitutes about 3%, DDE 1%, and free DDA 25-35%; the remaining consists of complexes of DDA or a closely related material. DDE is the principal storage form of ingested DDT in man. However, while men stores about 60% of DDT-derived material in the form of DDE, rats store only about 22-29% of DDE, and monkeys convert little or no DDT to DDE.
TL;DR: It is concluded that the regulation of adenosine responses and the action of dipyridamole in the heart involve a more direct association with coronary vascular tissue than has been previously appreciated.
Abstract: 1 The actions and interactions of adenosine and dipyridamole were investigated on isolated strips of coronary arteries of beef cattle. It was found that small diameter arteries (about 0.5-1.0 mm o9d.), raised to a moderate level of tone with potassium, responded with relaxation to low concentrations of adenosine. 2 Dipyridamole, over a broad concentration range (6.0 X 10(-8)-2.0 X 10(-5)M), enhanced these responses, shifting the adenosine concentration-response curve (3.7 X 10(-8)-1.1 X 10(-4)M) considerably to the left. In contrast, inhibitory concentrations-response curves to sodium nitrite and to noradrenaline were not materially altered by dipyridamole. 3 Studies of the uptake of [3H]-adenosine revealed a rapid uptake of the nucleoside by coronary artery strips, which was inhibited by dipyridamole (6.0X 10(-8)-2.0X10(-5)M); but this may not be sufficient to account fully for the observed sensitization. 4 It is concluded that the regulation of adenosine responses and the action of dipyridamole in the heart involve a more direct association with coronary vascular tissue than has been previously appreciated.
TL;DR: In this article, the authors show that the composite peak observed in the unimolecular fragmentation (i) [C3H4]-· [C 3H3]+ + H· is present only if the decomposing molecular ion is large enough to also produce [C6H8]2+ ions.
Abstract: Composite metastable peaks are generated in the unimolecular fragmentations (i) [C3H5]+ [C3H3]+ + H2 (flat-top upon flat-top) and (ii) [C4H9]+ [C3H5]+ + CH4 (flat-top and gaussian). The measurement of appearance potentials and kinetic energy releases lead us to conclude, in agreement with earlier proposals, that in (i) the components can arise from the generation of the isomeric cyclopropenium and propargyl daughter cations. In (ii) the components are proposed to arise from the fragmentation of tert- and sec-butyl cations yielding allyl as the common daughter ion.
The composite peak observed in the fragmentation (iii) [C3H4]+· [C3H3]+ + H· is shown to be present only if the decomposing molecular ion is large enough to also produce [C6H8]2+ ions. The second component in (iii) then arises from the reaction [C6H8]2+ [C6H6]2+ + H2.
TL;DR: The large quattities of marine phytoplankton passing through the cooling systems of two Southern California coastal power plants were found to be greatly reduced in numbers and in volume, and the severity of the impact appears to be controlled by two interacting factors: intake water-temperature and magnitude of temperature increase.
Abstract: The large quattities of marine phytoplankton passing through the cooling systems of two Southern California coastal power plants were found to be greatly reduced in numbers (41.7%) and in volume (33.7%). The biomass killed from June, 1972 to May, 1973 amounted to approximately 1,700 tons of organic carbon. Phytoplankton mortalities were most pronounced from October to December when intake waters of 17° to 20°C were subjected to temperature elevations of 9 to 11C°, and were lowest from January to March when cooler ambient temperatures prevailed. There was no apparent reduction in phytoplankton stocks when the intake water was cooler than 15°C. Surviving cells in 25° and 26.5°C effluent waters were growing three times faster than influent populations, which suggests that power-plant effects on phytoplankton stocks are often short-lived. However, entrainment effects appear very disruptive, in changing the structure of phytoplankton communities and in constantly reducing species diversity (H′). Passage through the condenser tubes affected algal species differentially, killing diatoms in greater numbers (45.7%) than dinoflagellates (32.8%), and reinforcing the dominance of the two major species, Asterionella japonica and Gonyaulax polyedra, that were the most tolerant. The severity of the impact appears to be controlled by two interacting factors: intake water-temperature and magnitude of temperature increase. On this basis, use by coastal power plants of deep-sea water for cooling is strongly advocated.
TL;DR: The importance of physicochemical methods used to purify and isolate haptens, and help in their definition, is stressed.
Abstract: Cross-sensitization between two plant allergens, Frullania and Laurus Nobilis (L.), has been demonstrated in Strabourg. A review of the haptens isolated from Frullania outlines the importance of the purification of allergen to ascertain the nature of the causative agent. New results on laurel oil point to the possibility of a common denominator (the a-methylene gamga-butyrolactone moiety) between this plant and Frullania; former results are re-interpreted and analyzed. In conclusion, the importance of physico-chemical methods used to purify and isolate haptens, and help in their definition, is stressed.
TL;DR: Pyruvate kinase was purified from sturgeon muscle in yeilds comparable with those obtained from the muscles of other species and gives a sigmoidal velocity curve with respect to phosphoenolpuruvate saturation.
Abstract: Pyruvate kinase was purified from sturgeon muscle in yeilds comparable with those obtained from the muscles of other species. In contrast with mammalian muscle pyruvate kinase the enzyme from sturgeon muscle gives a sigmoidal velocity curve with respect to phosphoenolpuruvate saturation, is activated by fructose 1.6-diphosphate, and is inhibited by bivalent copper ions. In these respects it is similar to the enzyme isolated from mammalian liver. The degree of interaction between phosphoenolpyruvate-binding sites is dependent on temperature.
TL;DR: In this article, the authors measured the metastable ion peak shapes, dimensions and relative abundances for the three fragmentations [C3H6]+· [c3H4]+· + H2, [CH6]-[CH4]-[cH5]- [cH3]-[H2]-] + H· and [H3H−[C3]−[H·+H·]−H· +H· and concluded that the differences in their internal energy differences can be attributed to internal energy difference.
Abstract: Metastable ion peak shapes, dimensions and relative abundances have been measured for the three fragmentations [C3H6]+· [C3H4]+· + H2, [C3H6]+· [C3H5]+ + H· and [C3H6]+· [C3H3]+ + H2 + H·. [C3H6]+· ions were derived from propene, cyclopropane, tetrahydrofuran, cyclohexanone, 2-methyl but-1-ene and cis-pent-2-ene. Activation energies for these fragmentations have been evaluated. Three daughter ion dissociations ([C3H5]+ [C3H3]+ + H2, [C3H5]+ [C3H4]+· + H· and [C3H4]+· [C3H3]+ + H·) have been similarly examined.
Ion structures have been determined and the metastable energy releases have been correlated with the thermochemical data. It is concluded that the molecular ions of propene and cyclopropane become structurally indistinguishable prior to fragmentation and that differences in their metastable ion characteristics can be ascribed wholly to internal energy differences; the latter can be correlated with the photoelectron spectra of the isomers. The pathway for the consecutive fragmentation which generates the metastable ion peak (m/e 42 m/e.39) has been shown to be
It is likewise concluded that fragmentating [C3H6]+· ions generated from the various precursor molecules are also structurally indistinguishable and cannot be classified with either molecular ion of the isomeric C3H6 hydrocarbons.
TL;DR: Evidence is presented that the relaxation from contractions induced by histamine and 5‐hydroxytryptamine also involves extraneuronal accumulation and release, probably by an uptake process which is identical to the one for catecholamines.
Abstract: 1 The role of the uptake and release of agonist from extraneuronal sites in the termination of responses of rabbit aortic strips to amines was studied. 2 Strips were contracted with adrenaline or noradrenaline and after response plateau was reached, the muscle chambers were washed free of agonist and the relaxation in Krebs solution recorded. After inhibition of catechol-O-methyl-transferase, monoamine oxidase and neuronal uptake the relaxation rate was greatly prolonged. Evidence is provided that this very slow relaxation resulted from the accumulation of intact amine at extraneuronal sites during exposure to the agonist and its subsequent release past receptors due to a reversal of the concentration gradient after washout. 3 Pretreatment with the haloalkylamine, GD-131 (N-cyclohexylmethyl-N-ethyl-beta-chloroethylamine), an inhibitor of extraneuronal uptake, returned the slow relaxation rate after enzyme inhibition towards that of control strips. By blocking the extraneuronal transport of amines their accumulation at intracellular loci after enzyme inhibition was prevented. 4 The effects of GD-131 and 17beta-oestradiol on the relaxation rate of untreated strips contracted by adrenaline and noradrenaline confirmed that extraneuronal uptake to sites of enzymatic activity is the major mechanism terminating their action. 5 Inactivation of extraneuronal transport sites by GD-131 was prevented by protecting them with 17beta-oestradiol or normetanephrine during exposure to the haloalkylamine, pointing to a common site of action of these agents on a specific carrier system for amines. 6 Evidence is presented that the relaxation from contractions induced by histamine and 5-hydroxytryptamine also involves extraneuronal accumulation and release, probably by an uptake process which is identical to the one for catecholamines.
TL;DR: The rate of 3H-ouabain binding was very sensitive to the potassium concentration, and was inhibited in a manner approximated by a first order competitive relationship.
TL;DR: In this article, the effects of 6-hydroxydopamine (6-OHDA) and guanethidine on locomotor activity in newborn rats were investigated. But, the results were not consistent with a simple interpretation either in terms of maturational changes in blood brain barrier permeability to 6-ohDA or neuronal uptake of the drug.
Abstract: Newborn rats received 7 consecutive daily injections of 6-hydroxydopamine (6-OHDA) or guanethidine. Locomotor activity, measured at 3 day intervals, was differentially affected by these drugs, although neither drug eliminated a characteristic pattern of ontogeny of locomotor activity. Differing neurochemical effects were also observed. 6-OHDA decreased tyrosine hydroxylase activity in cortex and cerebellum, increased it in the brainstem and had no effect on the hypothalamus. Guanethidine slightly elevated enzyme levels in all four brain regions, with the elevation in brainstem significant at 16 days of age. Regional brain changes in enzyme activity after 4 daily 6-OHDA injections beginning at 1, 5 or 9 days of age indicated that toxic effect of 6-OHDA upon catecholaminergic neurons was age dependent. These data are not consistent with a simple interpretation either in terms of maturational changes in blood brain barrier permeability to 6-OHDA or neuronal uptake of the drug. Further analyses of brainstem areas indicated that the increased brainstem enzyme activity after 6-OHDA was restricted to the pons.