Showing papers by "University of Ottawa published in 1970"
TL;DR: In this article, the temperature dependence of the elastic stiffness constants was investigated for 57 elastic constants of 22 substances and the applicability of these two equations and that of Wachtman's equation was examined.
Abstract: The following two equations are proposed for the temperature dependence of the elastic stiffness constants: ${c}_{\mathrm{ij}}={c}_{\mathrm{ij}}^{0}\ensuremath{-}\frac{s}{({e}^{\frac{t}{T}}\ensuremath{-}1)}$ and ${c}_{\mathrm{ij}}=a\ensuremath{-}\frac{b{T}^{2}}{(T+c)}$, where ${c}_{\mathrm{ij}}^{0}$, $s$, $t$, $a$, $b$, and $c$ are constants. The applicability of these two equations and that of Wachtman's equation is examined for 57 elastic constants of 22 substances. The first equation has a theoretical justification and gives the best over-all results. Neither of the three equations give the theoretically expected ${T}^{4}$ dependence at low temperatures, and therefore they are not expected to give very accurate results at very low temperatures ($\ensuremath{\lesssim}\frac{{\ensuremath{\Theta}}_{D}}{50}$). A new melting criterion is also examined.
606 citations
TL;DR: Phospholipids and glycolipids exist in a dynamic state of equilibrium in the membrane structures of plant cells, as may be readily demonstrated in studies using radioisotopes.
Abstract: Publisher Summary This chapter describes the composition and cellular distribution of plant phospholipids and glycolipids and their cellular metabolism. Early studies on the lipids of plants had revealed only the presence of components well known in animal tissues, namely, phosphatidylcholine (lecithin), phosphatidylethanolamine and phosphatidylserine (cephalins), and phosphatidylinositol. Phosphatidic acid had been isolated from plant tissue and was considered to be a characteristic plant phosphatide, but this component was subsequently shown to be largely an artifact formed by enzymatic degradation during extraction of the lipids. Distribution of unsaturated fatty acids among the phospholipid and glycolipid components of both photosynthetic and nonphotosynthetic tissues is by no means uniform. In general, the galactolipids have very high contents of linolenic and C16 -trienoic acids in photosynthetic tissues grown in the light, or linoleic acid in nonphotosynthetic tissues. Phospholipids and glycolipids exist in a dynamic state of equilibrium in the membrane structures of plant cells, as may be readily demonstrated in studies using radioisotopes. Rapid incorporation of radioisotopes observed when plants cells are exposed to labeled presursors such as phosphate- 32P or 14CO2 is the result of a steady-state cycle of degradative and synthesizing reactions.
189 citations
TL;DR: The results thus suggest that the categorization of lymphoid cells into the “short-lived” and the "long-lived" categories is a gross oversimplification, and are consistent with the interpretation that there are a multitude of subclasses of lymphoids cells, having discretely different life expectancies in the range from a few days or less to well over 1 month.
182 citations
TL;DR: Electrolytic lesions were placed in various sites of the body of the caudate nucleus, and the distribution of the degenerating fibers was studied in sections stained by the Nauta silver impregnation technique or by the method of Fink and Heimer.
167 citations
TL;DR: A new method is described for attaching an enzyme to the surface of a nylon tube by linking free amino groups on the enzyme to amino groups in the nylon through the bifunctional reagent glutaraldehyde.
114 citations
TL;DR: The results are consistent with a postulated working hypothesis that lymphocyte stimulation involves an early and protracted activation of membrane transport Na-K-ATPase, and is critically dependent on a subsequent increase of intracellular potassium which is suppressed by ouabain.
109 citations
TL;DR: In this paper, a theoretical technique to predict the thermal conductivity of heterogeneous mixtures, previously derived by the writers, has been applied to suspensions, emulsions and porous materials.
103 citations
TL;DR: The fine structure of the osteocytes and of the immediately adjacent bone matrix has been studied in the jaws of young rats demineralized with EDTA and no evidence of regeneration (“osteoplasia”) has been observed.
Abstract: The fine structure of the osteocytes and of the immediately adjacent bone matrix has been studied in the jaws of young rats demineralized with EDTA. The events marking the life cycle of the cell and their effects on the pericellular bone substance have been grouped into 3 phases. 1. The formative period, where the osteocyte resembles an osteoblast but shows a gradual decrease in the amount of endoplasmic reticulum and in the size of the Golgi complex. 2. The beginning of resorption (osteocytic osteolysis) which is characterized by a further decrease of the secretory organelles and the jagged appearance of the perilacunar border. Later in this phase there is further development and activity of the lysosomes resulting in increased widening of the lacuna and accumulation in the lacuna of fibrillar and flocculent material. 3. The eventual degeneration and death of the cell. No evidence of regeneration (“osteoplasia”) has been observed.
67 citations
TL;DR: Both types of experiment confirm the channeling hypothesis, where the carbamyl phosphate synthetase and the aspartate transcarbamylase activities were associated in the complex, most of the product of the first reaction was not free to become converted to citrulline but was channeled preferentially into Carbamyl aspartates.
66 citations
60 citations
TL;DR: It is postulated from these results that an accumulation of triglyceride in the rabbit heart in response to ethanol administration is a result of decreased fatty acid oxidation rather than of increased triglyceride uptake or increased fatty acid synthesis.
Abstract: Ethanol in saline solution (15%, v/v) was infused into anesthetized rabbits at a rate of 0.494 ml/min for the first 12 minutes and then at 0.247 ml/min for 108 minutes. Three hours after the infusion, heart triglyceride and lipoprotein lipase were assayed. Oxidation and esterification of fatty acids (palmitate-14C as an indicator) were assessed by using either tissue homogenates or perfused hearts taken from the rabbits. Oxidation-reduction states of the perfused hearts were examined by measuring the tissue levels of dehydrogenase-linked substrates. The infusion of ethanol resulted in 180% increase in heart triglyceride content, but the infusion of norepinephrine (3 µg/kg/min) did not change the content. No change in plasma free fatty acids and triglyceride or heart lipoprotein lipase activity was detected. Addition of ethanol had little effect on the distribution of palmitate-14C in the lipids of tissue slices and homogenates. On the other hand, prior infusion of ethanol resulted in depression of 14CO2 p...
TL;DR: Shifts of some of the aromatic resonances of tyrosine and phenylalanine in lysine-vasopressin relative to the values observed in monomers and in substituted oxytocins are indicative of stacking of the aroma rings, leading to a model for the stack.
TL;DR: The present investigation indicates that DDT analogs possess uterotrophic activity and that, analogous to the action of estrogens on uterine tissue, they are capable of inducing new synthesis of several carbohydrate-metabolizing enzymes.
TL;DR: In this paper, the results of an investigation of the anomalous behavior of aqueous hydroxyethyl cellulose (Natrosol-250G) solutions in the vicinity of solid surfaces, in laminar flow through capillary tubes, are presented.
Journal Article•
TL;DR: Leptocurares and pachycurares as modifiers of conformation find an exact parallel in the divergence of their mechanisms of blockade at the myoneural junction level, providing new insight into the interaction topographies underlying the ligand-induced conformational changes.
Abstract: It was shown previously that the alkyltrimethylammonium ion series of cholinergicl and anticholinergic drugs not only fail to protect acetylcholinesterase (AChE) against irreversible esterification by methanesulfonyl fluoride of its active serine hydroxyl, but actually accelerate the reaction, thus showing that the alkyl chains do not bind bind on the catalytic esteratic sites themselves ( exo orientation). Acceleration has been explain in terms of conformational perturbations, and maximum potency in this regard was exhibited by the n -hexyl membber, followed by a sharp reversal of the acceleration trend at the n -heptyl member. Parallel trends and shifts in potencies at the receptor level are well documented. Using the same experimental techniques, it has now been found that leptocurares (polymethoniums of the decamethonium series, including succinylcholine) also behave as accelerators of the methanesulfonylation reaction, peak activity being observed with decamethonium. Succinylcholine was 4 times more active than the latter in stimulating the methanesulfonylation reaction. The trend in stimulating potencies closely parallels the relative blocking potencies at the motor end plate level. In marked contrast, d -tubocurarine and gallamine protect AChE against methanesulfonyl fluoride by a mechanism which does not obey the laws of competitive kinetics. The application of conventional assay techniques had previously led to the conclusion that pachycurares are competitive inhibitors of the cationic substrate ACh at both the enzyme and myoneural junction levels. However, evidence that the inhibition is rather of the partially competitive type has recently been reported. Since the methanesulfonyl fluoride molecule, unlike ACh, carries no charge, it can hardly compete directly with pachycurares for charged binding sites. Hence, the observed partially competitive relationship must be the result of pachycurare-induced change transmitted to the esteratic center from outer anionic sites. These contrasting properties of leptocurares and pachycurares as modifiers of conformation find an exact parallel in the divergence of their mechanisms of blockade at the myoneural junction level. These observations furnish new insight into the interaction topographies underlying the ligand-induced conformational changes.
TL;DR: In cementum of rat molars, the cementoblasts were found to differ from pre‐cementoblasts in having an increased granular endoplasmic reticulum, greater number of polyribosomes and denser material in the cisternae of granular E. R. as well as in the general cytoplasm.
Abstract: In cementum of rat molars, the cementoblasts were found to differ from pre-cementoblasts in having an increased granular endoplasmic reticulum, greater number of polyribosomes and denser material in the cisternae of granular E. R. as well as in the general cytoplasm. The cementocytes with maturation showed a gradual decrease in the size of the Golgi complex and the granular endoplasmic reticulum. On the other hand, an increase in the number of lysosomes was observed. Parallel with these intracellular changes, the pericullular space became irregular in width, its fibrillar material became replaced by a flocculent material. Ocasionally, structurally different matrix was seen. At the cemento-dentinal junction the cementocytes showed degenerative changes indicative of degeneration and death. The epithelial cells, remnants of Hertwig's root-sheath, some of which get enclosed in the cementum, accumulated filamentous material as well as spheres of amorphous substance. These cells eventually degenerated, leaving their debris in the lacunae. The degeneration of epithelial cells did not seem to affect the cementum matrix in their immediate vicinity. Some collagen fibrils of the cementum, seemed to differ structurally from those of the periodontal membrane. Thin fibrils, about 160 A in diameter, were also observed in the cementum.
TL;DR: The evidence indicates that cyclic adenosine monophosphate may be involved as an intermediary in the action of androgenic hormones on male accessory sex organs.
Abstract: Administration of adenosine 3',5'-monophosphate with theophylline produced testosterone-like induction of hexokinase, phosphofructokinase, pyruvate kinase, and glucose-6-phosphate dehydrogenase in the seminal vesicles of both orchidectomized and immature rats. The N(6)-O(2)'-dibutyryl analog of this cyclic nucleotide produced greater increases in vesicular enzyme activities than those induced by the parent compound. The observed enhancement of the key glycolytic enzymes and of hexose monophosphate shunt dehydrogenase was significantly inhibited by actinomycin D and cycloheximide. The evidence indicates that cyclic adenosine monophosphate may be involved as an intermediary in the action of androgenic hormones on male accessory sex organs.
TL;DR: Brown adipose tissue is unusual in the extent to which it can increase its metabolic rate when stimulated by noradrenaline both in vivo and in vitro, and may play another role in the adaptation for nonshivering thermogenesis, namely, that of an endocrine organ.
TL;DR: The hypothesis that homologous chromosomes or genomes require similar duration for their DNA synthesis and suggest that the structures of chromosomes are involved in temporal control of the DNA synthesis in cells is supported.
Abstract: The relative amounts of nuclear DNA of root meristematic cells of two related diploid Avena species, A. strigosa 2x and A. pilosa, which have different karyotypes, and an autotetraploid of one, A. strigosa 4x, were measured by Feulgen microspectrophotometry. The durations of various periods of their mitotic cycles were studied by autoradiography of cells pulse-labeled with tritiated thymidine. The results show that the autotetraploid, with twice the amount of nuclear DNA of its diploid, has the same duration of S period as the diploid, while A. pilosa, with intermediate nuclear DNA content, has a longer S period. These results support the hypothesis that homologous chromosomes or genomes require similar duration for their DNA synthesis and suggest that the structures of chromosomes are involved in temporal control of the DNA synthesis in cells.
TL;DR: Steroid glucosyl-, glucuronyl-, and N-acetylglucosaminyltransferases from rabbit liver microsomes have been partially purified by detergent solubilization and ammonium sulfate precipitation and it has been established that the transfer is to the phenolic 3-hydroxyl group.
TL;DR: In this paper, the mass spectra of o-nitrobenzoic acid and other compounds have been studied and the importance of nitro to nitrite conversion in molecular and fragment ions is discussed.
Abstract: The mass spectra of o-nitrobenzoic acid, o-nitroanisole, o-nitrosobenzoic acid, o-nitrobenzamide, o-nitrobenzyl alcohol and o-nitrosobenzaldehyde have been studied. Fragmentation mechanisms are proposed for the above compounds; their elucidation was aided by isotopic labeling with D and O18. Two ‘ortho-effects’ are discussed; one involving H atom transfer between substituents and the other migration of an atom or group to a charge carrying vacant ortho position. The importance of nitro to nitrite conversion in molecular and fragment ions is discussed.
TL;DR: Perturbation of the testosterone spectrum is linear in intensity up to a value of v = 1.2 and suggests hydrogen bonding at the binding site and the associated perturbations of the lone tryptophan residue are shown to be quantitatively significant and dependent on steroid structure.
TL;DR: In this article, the design of a gas solubility apparatus utilizing the basic principle of the Morrison and Billet apparatus is described, and the solubilities at atmospheric pressure of ethane in the normal paraffin solvents, hexane, heptane, octane, dodecane and hexadecane, and also of the same gas in the two-component solvent solutions consisting of hexane and HexadecANE are reported.
Abstract: The design of a gas solubility apparatus utilizing the basic principle of the Morrison and Billet apparatus is described. The solubilities at atmospheric pressure of ethane in the normal paraffin solvents, hexane, heptane, octane, dodecane and hexadecane, and also of the same gas in the two-component solvent solutions consisting of hexane and hexadecane are reported. The solubilities of twelve gases were empirically correlated utilizing one constant for each gas. The empirical equations permit an estimate of the solubility in any normal paraffin solvent from hexane to hexadecane and for any temperature between 15°C and 40°C from a single solubility measurement.
On decrit la conception d'un appareil pour la solubilite des gaz, lequel est base sur le principe fondamental de l'appareil de Morrison et Billet. On rapporte les resultats de solubilite de l'ethane a la pression atmospherique dans les solvants paraffiniques a chaǐne droite, a savoir l'hexane, l'heptane, l'octane, le dodecane et l'hexadecane, ainsi que dans deux solvants ensemble, l'hexane et l'hexadecane. On a etabli une correlation empirique entre les resultats de solubilite de 12 gaz en utilisant une constante pour chaque gaz. Les equations empiriques permettent d'evaluer la solubilite dans n'importe quel solvant paraffinique a chaǐne droite, en allant de l'hexane a l'hexadecane et pour n'importe quelle temperature comprise entre 15°C et 40°C, en n'utilisant qu'une seule mesure de solubilite.
TL;DR: In this paper, the mass spectrum and fragmentation mechanism of thiobenzoic acid and its carboxyl deuterated derivative were studied in detail and the role of ortho hydrogen atoms in rearrangements was discussed.
Abstract: The mass spectra of benzoic acid and its carboxyl-deuterated derivative have been studied in detail. Molecular and fragment ion structures are proposed and the role of ortho hydrogen atoms in rearrangements is discussed. The behaviour under electron-impact of phthalaldehydic acid and its carboxyl deuterated derivative provides evidence in support of ion structures in the benzoic acid fragmentation. From these results the fragmentation mechanism for phthalic acid is further elucidated. The mass spectrum and fragmentation mechanism of thiobenzoic acid is described and compared with that of benzoic acid.
TL;DR: The data support the suggestion that cyclic AMP may be involved in triggering the known metaboli and that treatment with the N6-O2'-dibutyryl analog of cyclicAMP resulted in greater increases in phosphofructokinase activity than those induced by the parent compound.
Abstract: Cyclic 3',5'-adenosine when, monophosphate injected concurrently with theophylline, produced a marked stimulation of phosphofructokinase activity in uteri of both ovariectomized and immature rats. Enzyme activity was elevated significantly as early as 1 hr and maximum increases were observed 16 hr after the administration of the cyclic nucleotide. The increase in uterine phosphofructokinase was dependent upon the dose of cyclic AMP. Treatment with the N6-O2'-dibutyryl analog of cyclic AMP resulted in greater increases in phosphofructokinase activity than those induced by the parent compound. Stimulation of the uterine enzyme by either cyclic AMP or its dibutyryl analog was independent of adrenal function. Actinomycin D and cycloheximide effectively prevented the cyclic AMP and theophyllineinduced increases in uterine phosphofructokinase activity in both ovariectomized and adrenalectomized- ovariectomized rats. The data support the suggestion that cyclic AMP may be involved in triggering the known metaboli...
TL;DR: In this article, a modified Redlich-Kwong equation of state was used to evaluate the partial molal volumes of normal fluid mixtures in the liquid state by means of a modified version of the Redlich and Kwong equation.
Abstract: Partial molal volumes of normal fluid mixtures in the liquid state were evaluated by means of a modified Redlich-Kwong equation of state. Molal volumes and vapor pressures of pure saturated liquids were used for evaluating the two parameters of the equation. These parameters were treated as temperature dependent. Partial molal volumes of six binary systems were satisfactorily predicted in this investigation. Satisfactory compressibility factors for pure liquids at high pressures were also obtained by the proposed method.
On a evalue, au moyen d'une equation d'etat de Redlich et Kwong modifiee, les volumes molaires partiels de melanges normaux de fluides a l'etat liquide. On a utilise les volumes molaires et les pressions de vapeur de liquides purs et satures pour determiner les deux parametres de l'equation qu'on a consideres comme dependants de la temperature. Cette etude a permis de predire d'une maniere satisfaisante les volumes molaires partiels de six systemes binaires. On a aussi obtenue, par la methode proposee, des facteurs de compressibilite satisfaisants dans le cas de liquides purs soumis a de hautes pressions.