Showing papers by "Université de Sherbrooke published in 1973"

Enthalpies of dilution of electrolyte solutions by flow microcalorimetry

Abstract: The enthalpies of dilution of NaCl, Me4NBr, andn-Bu4NBr were measured in water at 25°C with a new flow microcalorimeter. The data were analyzed with a polynomial equation, and the derived relative apparent molal enthalpies φL are in good agreement with literature values. Provided care is taken that mixing is complete, flow calorimeters are as reliable and much less time-consuming than cell-type instruments for enthalpies of dilution measurements.

Growth of normal and transformed rat embryo fibroblasts: effects of glycolipids from Salmonella minnesota R mutants.

Abstract: Addition of glycolipids obtained from Salmonella minnesota R mutants to normal, spontaneously transformed, and SV40-transformed rat embryo fibroblasts in culture results in an inhibition of growth of transformed cells but not of normal cells. In the presence of the glycolipid with the smallest carbohydrate chain length, spontaneously transformed cells stop growing when they reach confluency. Inhibition of growth of transformed cells is inversely related to the chain length of the core sugars. Glycolipid mR595 is shown to bind with the cell membrane of transformed cells and elicits an augmentation in the intracellular level of cyclic AMP. Normal cells bind relatively less glycolipid mR595 and show a lower percent of increase in cyclic AMP due to glycolipid mR595 than do transformed cells.

Ionic interactions in water.

Abstract: By comparing the accurately calculated thermodynamic properties of solution models with the thermodynamic excess functions of real aqueous solutions, it is possible to reach detailed conclusions about the contribution of solvation to ion-ion forces and to other solute-solute forces as well. While there are some ambiguities that remain to be resolved by comparison with other types of experimental data, it seems clear that the data used here are consistent with models in which the ions are not rigidly hydrated; rather the hydration layers, even of Li+ and Mg++, seem to be penetrated in collisions with other solute particles in solution. This study includes alkali halides, alkaline earth halides, tetraalkyl ammonium halides, some nonelectrolytes, and various mixtures, all at concentrations of up to about 1 M. Once the solvation parameters in the models are adjusted to fit the data, one gets good agreement of model and experiment for the osmotic and activity coefficients, the heats of dilution, and the apparent molal volumes over this range. The theory necessary to calculate Setchenow coefficients from pair correlation functions that are derived from a model is also given in this paper. The result provides some striking examples of the effect of Coulomb (COUL) forces on the concentration dependence of the zeroth moments J(g l )d3r of the pair correlation functions.

Balanced correlated ternary coding system

Abstract: A balanced correlated ternary coding system including a modulator, a demodulator and an error detector. The modulator is designed so as to code a binary signal of level 0 or 1 into a ternary signal of level +, 0, or - according to any of the following truth tables:

Electron microscopic-immunocytochemical localization of adrenocorticotropin and melanocyte stimulating hormone in the pars intermedia cells of rats and mice.

Abstract: Electron microscopic localization of adrenocorticotropin (ACTH) and melanocyte stimulating hormone (MSH) in light, dark and ACTH cells in the pars intermedia (PI) of rats and mice is attempted by using antisera to βp 1–24, βp 17–39 ACTH and βb MSH with the immunoglobulin-peroxidase bridge technique. All of the PI parenchymatous cells (light, dark and ACTH cells), except the marginal cuboidal and the ependymal like cells, in rats and mice show very good localization of ACTH and MSH staining. In the light and dark cells, stain of varying intensity is seen on the secretory granules, vesicles and also in many places on the surface of the rough endoplasmic reticulum. There is no staining on the mitochondria, in the nuclei or in the granules inside and around the cisternae of the Golgi complex. Dark stained dense core granules become larger and larger as they appear farther and farther away from the Golgi complex. On the other hand, in the ACTH cells of the PI, ACTH antisera show stronger stained granules in the Golgi complex including the cisternae, similar to the pars distalis (PD) ACTH cells. From these observations it is concluded that the corticotropin in light and dark cells, is not packaged or condensed in the Golgi complex like that in the ACTH cells. MSH synthesis in light and dark cells also seems to be similar to that of ACTH synthesis. It is likely that the granules accumulate ACTH and MSH secretions after they are liberated from the Golgi cisternae, and thus become bigger and bigger in size. In case of ACTH cells of PI and PD, corticotropin may be packaged in Golgi cisternae and the size of the granule does not change much. This shows that there are distinct immunocytochemical differences between the light, dark and ACTH cells of the PI. At the moment, it is difficult to say whether ACTH and MSH are present in the same granule or not.

Ganglioside patterns and phenotypic characteristics in a normal variant and a transformed back variant of a simian virus 40-induced hamster tumor cell line

Abstract: Ganglioside patterns of a cloned Simian virus 40- (SV40) induced hamster tumor cell (Cl(2)TSV(5)-S), its normal variant (Cl(2)TSV(5)-R) which are Cl(2)TSV(5)-S gradually adapted to grow in the presence of 2 microg/ml actinomycin D and exhibit certain normal phenotypic characteristics, and its back variant (Cl(2)TSV(5)-RR), which are Cl(2)TSV(5)-R cells grown in the absence of actinomycin D for more than 60 passages and which exhibit greater phenotypic similarity to Cl(2)TSV(5)-S cells, have been analyzed. All three cell lines contain N(acetylneuraminyl) galactosylglycosyl ceramide (hematoside, GM(3)), N-acetylgalactosaminyl (N-acetylneuraminyl) galactosylglucosyl ceramide (GM(2)), and a higher ganglioside tentatively identified as disialohematoside. However, Cl(2)TSV(5)-R have more GM(2) than Cl(2)TSV(5)-S whereas Cl(2)TSV(5)-RR contain an intermediate amount of GM(2). The amount of GM(2) is correlative with the activity of UDP-N-acetylgalactosamine: hematoside N-acetylgalactosaminyl transferase in the extract of the three cell lines and with their agglutination by wheat germ agglutinin.

Immunohistochemical localization of adrenocorticotropin and melanocyte stimulating hormone in pars intermedia of rat hypophysis.

Abstract: The sites of production of adrenocorticotropin (ACTH) and melanocyte stimulating hormone (MSH) are studied by the immunoglobulin-peroxidase bridge technique, using antisera prepared against synthetic porcine β 1–24 and β 17–39 ACTH, and bovine β MSH on the rat adenohypophysis. Presence of ACTH all over the pars intermedia (PI) is indicated by staining with antisera βp 1–24 and βp 17-3-9 ACTH. There are darkly stained ACTH cells in the PI and pars tuberalis (PT), similar to those in the pars distalis (PD). With higher dilutions of the ACTH antiserum, staining intensity disappears or reduces markedly in majority of the PI cells, whereas, the ACTH cells in the PI, PD and PT do not vary much in their staining intensity. Therefore, it is concluded that majority of the PI glandular cells (light glandular and dark cells) contain less corticotropin than the ACTH cells. From these observations, it seems to me that the major amount of corticotropin is supplied by the ACTH cells of the PD, PI and PT, and less by the light glandular and dark cells of the PI. The antiserum is ineffective after absorption, so the staining reaction appears to be specific for βp 1–24 and βb 17–39 ACTH.

Three-Dimensional Finite Element Analyses of Dams

Abstract: Three-dimensional finite element analyses were performed for dams in valleys with valley wall slopes of 1:1, 3:1, and 6:1. The results were compared with the results of two-dimensional analyses to evaluate the accuracy of two-dimensional analyses. The conclusions were: (1) plane strain analyses of the maximum transverse section provide accurate results for dams in valleys with valley wall slopes 3:1 or flatter; (2) plane stress analyses of the maximum longitudinal section do not provide accurate results; and (3) plane strain analyses of the maximum longitudinal section provide fairly accurate results for all valley wall slopes.

Changes in plasma levels of vasopressin and renin in response to haemorrhage in dogs.

Abstract: 1. The rabbit rectum superfused with blood or Krebs solution was used to assay vasopressin in circulating blood and in plasma extracts respectively.2. Vasopressin was released by a rapid fall in diastolic pressure of as little as 5 mmHg, and the amount of vasopressin released was proportional to the magnitude of the fall in diastolic pressure in the range studied. These results would indicate that vasopressin release follows the magnitude of the fall in diastolic pressure more closely than the actual decrease in blood volume in haemorrhagic hypotension.3. It was shown that the time required to induce an increase in circulating vasopressin is inversely proportional to the severity of the fall in diastolic pressure; this suggested that the stimulation of neurosecretory reflex arc varies with the intensity of the stimulus.4. The slight changes in plasma renin activity as well as the pattern of renin release suggested the unlikeliness of the influence of renin upon vasopressin secretion under these circumstances. On the contrary, the results suggested that the secretion of large amounts of vasopressin tended to inhibit renin release.

Acute Necrotizing Hemorrhagic Encephalopathy

Abstract: Acute necrotizing hemorrhagic encephalopathy is a demyelinating disease with a short, fulminating clinical course and a fatal outcome. The disease is diagnosed at autopsy in most cases. The pertinent non neurologic findings which may help in making the diagnosis in life are presented. With greater understanding of the immunologic aspects of this illness, a rational therapy and a possible cure may be offered.

Field dependence and self-disclosure)

Abstract: Some characteristics of the social behavior of field-dependents as well as their superior recognition of ambiguous social stimuli led to the hypothesis that they would show greater self-disclosure than field-independents. This hypothesis was tested by administering the 60-item Jourard Self-disclosure Questionnaire (JSDQ) to 13 field-dependent and 13 field-independent Ss. In terms of total self-disclosure scores, field-dependents showed significantly (.025) higher levels than field-independents. Results are discussed in light of personality theories which emphasize the role of self-conceptual transactions in the development of the self.

Discrete ulcerations of the rectum and sigmoid.

Abstract: In 35 patients with punched out ulcerations of the rectum and/or sigmoid, 12 different etiologies were found to be responsible for the lesions. Regional enteritis and traumatic ulcerations were the most frequently made diagnoses. One patient suffered from ulcerations of a chronic progressive nature which healed after vascular reconstruction of the inferior mesenteric artery. Evaluation of the pathologic material accumulated on patients with regional enteritis demonstrated the value to the pathologist of more than one biopsy. Thus, extensive investigations should be done in all patients with discrete ulcerations of the rectum and sigmoid, and a diagnosis of regional enteritis should not be excluded on the basis of pathology alone, especially when only a single biopsy has been obtained.

Digital compressor-expander

Abstract: A compressor-expander for converting m digit coded signals into n digit coded signals according to a desired input-output continuous characteristic. The compressor comprises first means for converting the m digit coded signals into p digit coded signals, p

Characterization of angiotensin receptors in vascular and intestinal smooth muscles

Abstract: 1. A series of analogues of angiotensin II (ATII) has been used in the present experiments to characterize receptors for ATII in intestinal (rat stomach strip, rat colon) and vascular (rabbit aorta) smooth muscles. Two types of compounds have been chosen: (a) agonists with reduced potency, in which 4-Tyr, 6-His or 7-Pro had been substituted with L-Ala or with Gly and 1-amino-cyclopentane carboxylic acid (Acpc) and (b) competitive antagonists (8-Gly-ATII, 8-Leu-ATII). 2. Replacement of 4-Tyr, 6-His and 7-Pro with L-Ala decreases the potency, but does not influence the maximum effect of the analogue, while substitution of the same residue with Gly and Acpc reduces both potency and maximum effect. 3. Compounds showing full size maximum responses were chosen to establish the following order of potency on the three preparations: ATII>4-Phe-ATII>7-Ala-ATII>6-Ala-ATII>4-Ala-ATII. 4. The four derivatives of ATII were completely inactive on tissues desensitized with ATII. The responses to 5-hydroxytryptamine, acetylcholine and noradrenaline were not significantly modified, except for the rat colon. 5. pA2 values for the two competitive antagonists against ATII and 4-Phe-ATII were estimated in the three preparations by the use of the cascade superfusion technique. For comparison, pA2 values were also estimated in rat stomach strips and rabbit aortas suspended in a normal organ bath, according to the method of Schild (1947). The similarities of the pA2 values obtained in two series of experiments indicate that (a) the cascade superfusion technique is suitable for this type of study and (b) the receptor for ATII in the three tissues may be the same. 6. It is suggested that receptors for ATII in intestinal and vascular smooth muscles may be the same, because (a) the order of potency of various agonists follows the same pattern, (b) the agonists are inactive on tissues desensitized with ATII, (c) pA2 values for competitive antagonists are similar in the three preparations.

Syllabic adaptative delta modulation system

Abstract: A syllabic adaptive delta modulation system including a modulator and a demodulator. The modulator comprises a comparator having a first input connected to receive an input analog signal, a second input adapted to be connected to an integrator located in the conventional feedback loop of the delta modulator and a quantizing means for sampling the output of the comparator to generate delta modulated binary pulses of one polarity or the other as determined by the comparator. A syllabic filter is connected to the output of the quantizing means for filtering the low frequency components of the delta modulated pulses and a multiplier is also connected to the output of the quantizing means and responsive to the syllabic filter for modulating the amplitude of the delta modulated pulses with the low frequency components detected by the syllabic filter. The integrator is connected to the output of the multiplier for integrating the amplitude modulated pulses. The output of the integrator is applied to the second input of the comparator for comparing the output signal of the integrator with the input analog signal and generating a signal depending upon the difference between the two signals.

Long term study of naproxen challenged by a short-term double blind cross-over study with placebo in rheumatoid patients.

Abstract: Naproxen is an effective anti-rheumatic agent, for the long-term control of active rheumatoid arthritis, as demonstrated by the experience of 28 patients. Subjecting 19 of these 28 patients to a double-blind crossover placebo pulse experiment revealed, by clinical observation and statistical analysis of collected data, that after more than 2 years of continuous daily administration naproxen exhibited a high degree of therapeutic activity. The tolerance of naproxen by this study population was good. Side effects or complaints, when reported, were mild and transient in nature. Close monitoring of a range of biochemical values by sequential laboratory studies has not revealed many adverse effects.

Fixation of a Salmonella minnesota R‐Form Glycolipid on the Membrane of Normal and Transformed Rat‐Embryo Fibroblasts

Abstract: Binding of Salmonella minnesota R form glycolipid mR595 to cultured rat embryo fibroblasts has been demonstrated by three methods: by uptake of labelled glycolipid, by passive hemagglutination and by immunofluorescence. The results by the three methods are correlative. Normal rat embryo fibroblasts exhibit lower fixation capacity than SV40 transformed rat embryo fibroblasts. Trypsinization of the two types of cells results in increased fixation of the bacterial glycolipid. Glycolipid mR595 binding is localized at the cell surface.

Circadian rhythm of alkaline phosphatase activity in the golgi zone of mouse duodenal enterocytes.

Abstract: Alkaline phosphatase activity has been analyzed by biochemical methods on mouse duodenal homogenates and by cytophotometric method over the Golgi region of the duodenal cells, at different time periods of the day in fasting and nonfasting animals. A circadian variation of the activity has been observed with a peak at 9.00 h and a nadir at 15.00 h in the homogenates. On the contrary, the cytophotometric measurements have shown a maximal activity over the Golgi zone at 15.00 h and a minimal activity at 9.00 h. These observations are compared with other circadian variations of intestinal enzymes.

The interaction of anionic detergents with lipid bilayer membranes.

Abstract: The time course of the reaction of anionic surfactants with lipid bilayers is followed and analyzed. The distribution of detergents in the membrane phase gives rise to an asymmetry potential followed by a diffusion potential. Detergent-doped membranes are cation-permselective. It is postulated that a variable profile of mobile charges in the membrane account for the cation-permselectivity, the intercation selectivity, and the voltage-dependent gating phenomena observed in excitable membranes.

Detection of single-stranded DNA in the nucleolus.

Abstract: A GC-rich DNA is reported in the nucleolus of ascites tumour cells which was extracted in a single stranded form differing from that reported for newly replicated DNA.