Showing papers by "Université de Sherbrooke published in 1972"

The viscosity of aqueous solutions of alkali and tetraalkylammonium halides at 25°C

Abstract: The viscosities of most alkali and tetraalkylammonium halides have been measured in water at 25°C. The relative viscosities can be fitted, up to 1M, with the relationηr=1+Aηc1/2+Bηc+Dη2. TheAη term depends on long-range coulombic forces, andBη is a function of the size and hydration of the solute. When combined with partial-molal-volume data, the difference Bη−0.0025V° is mostly a measure of the solute-solvent interactions. IonicBη are obtained if the tetraethylammonium ion is assumed to obey Einstein's law. TheDη parameter depends on higher terms of the long-range coulombic forces, on higher terms of the hydrodynamic effect, and on structural solute-solute interactions. As such, it cannot be interpreted unambiguously.

A survey of health problems, practices, and needs of youth.

Abstract: In a study of the health needs of youth, about 1,400 young adults were questioned on their health habits, health status, and the need for a special type of clinic. Concerning medical care practices, most consult their physician less than once a year and many never do so because they are not sick. A surprising number use the services of pseudo-medical men. Of the health problems of youth, nervousness and dental troubles are most frequent. Acne is considered an important problem by both sexes as is anxiety over health. Among the problems classed as personal, scholastic problems rate highest with family problems second in frequency and sex and religious problems taking third and fourth rank. The problems of most concern to some segments of our society today, namely drugs and alcoholism, rate lowest as problems personally affecting youth. Most wanted in a youth clinic are physicians, friends, and parents. The characteristics most sought in a physician are a high degree of understanding, a good personality, and informality. His age, sex, and dress seem to be of minor concern. A youth clinic should provide counsel and information on sex, drugs, venereal diseases, and alcoholism.

Is a specific protein responsible for the supercoiling of polyoma DNA

Abstract: POLYOMA and SV40 DNAs contain enough genetic information to code for half a dozen proteins. Very little is known about these proteins, although their recognition is of great interest in view of the oncogenic potential of the genomes. Recently, however, polyoma DNA from productively infected cells was isolated in the form of a protein–DNA complex distinct from the virus1 (our work in preparation). In an attempt to explore the nature and function of its protein moiety, we have investigated the effect of various inhibitors of protein synthesis on the formation and properties of this complex. We report here the results we obtained with puromycin.

Apparent molal heat capacities of transfer from H2O to D2O of tetraalkylammonium bromides

Abstract: The volumetric specific heats (in J-K−1-cm−3) of tetraalkylammonium bromides (R 4 NBr) have been measured at 25°C in the concentration range 0.02 to 0.4 aquamolal in H 2 O and D 2 O with a differential flow microcalorimeter. The apparent molal heat capacities φc, calculated from the specific heats and known densities, were fitted with the equation φc=φ c o +Acm1/2+Bcm whereA c is the Debye-Huckel limiting slope andB c is an adjustable parameter. The standard heat capacity of transfer ΔC ptr o =φ c o (D 2 O-φ c o (H 2 O) of R 4 NBr is positive forR equal ton-propyl andn-butyl and negative for methyl and ethyl. Except for Me 4 NBr in H 2 O, allB c are negative and become more so as the size of the cation increases;B c is usually more negative in D 2 O. These results can be interpreted with a two-state model for water and show that a positive ΔC ptr o is evidence that the solute is an overall structure maker, while a negative value indicates a net structure breaker. The negativeB c is consistent with the existence of strong solute-solute structural (mostly hydrophobic-hydrophobic and hydrophobic-hydrophilic) interactions in the solution.

Efficient Algorithm for Distribution Networks

Abstract: Because of the characteristics of the Jacobian matrix, modifications to the Newton’s approach of solving pipe networks can be done in such a way that convergence toward the solution is ensured, com...

Electron microscopic observations on the contribution of the ultimobranchial bodies to thyroid histogenesis in the rat.

Abstract: The fine structure of ultimobranchial bodies in the rat has been studied from the fifteenth to the twentieth day of gestation. At 15 days, the ultimobranchial bodies were still separated from the median thyroid primordium by connective tissue. Their lumina were filled with cellular debris and their thick walls were made up of one type of cell in which rough-surfaced endoplasmic reticulum was scanty. Early in the sixteenth day, cell cords from the median thyroid primordium came in direct contact with the ultimobranchial bodies; no basal lamina separated them. At 17 days the walls of the ultimobranchial bodies were composed of C cells, glycogen-rich cells and cells that were poor in rough-surfaced membranes and glycogen. At 18 days three types of cells were present in cell cords in direct contact with the ultimobranchial bodies: C cells, glycogen-rich cells and follicular cells. The first two cell types had migrated from the ultimobranchial bodies while the follicular cells had originated from the median primordium. In the same cell cords, follicular cells containing glycogen granules were interpreted as being an intermediate stage between glycogen-rich cells and true follicular cells. In follicular cells of the isthmus region, which presumably originate from the median primordium alone, glycogen granules were not observed after the fifteenth day of development. It is concluded that C cells and few follicular cells are of ultimobranchial origin.

Stimulation of Pancreatic Amylase Secretion and Protein Synthesis by Insulin

Abstract: In vivo studies indicate that insulin treatment is associated with increases in pancreatic amylase secretion and total protein synthesis. Any direct action of insulin on secretion and synthesis has been ruled out by in vitro studies. The stimulus involved appears then to be under vagal control and localized to the stomach. Our results support the concept of the existence of a gastric hormone involved in this control.

System for conducting automatically an audiometric test

Abstract: The disclosure herein describes a system for conducting automatically an audiometric test using a data processing means, in which are stored a series of tone frequencies, amplitude levels and time periods, and including a circuitry enabling the application of stimuli to a subject. Depending on each response received from the subject in answer to a given tone frequency, the apparatus will (1) continue the test utilizing a different amplitude level for the same tone frequency, (2) register the minimum threshold of the tone frequency, (3) continue the test utilizing a different tone frequency, or (4) register an aberration. The apparatus also enables the application of a vocal test to a subject in which the subject must indicate which word in a series of displayed words was heard.

Multiple Drug Use Among Marijuana Smokers in Eastern Canada

Abstract: Emphasis has recently shifted from an almost exclusive focus on the social and psychological characteristics of those who use particular drugs to special consideration of the users' relationships to the use of other substances. It is only proper that this should be the case. The clearest datum that emerges from studies of drug use is that those who use any one drug are more likely to use any other drug than those who do not use that drug The important questions are the following (a) what is the magnitude of this relationship?; (b) with what other drugs is this relationship strongest?; and (c) what is the significance of this relationship?

Electron microscopy of previously identified cells and processes within the central nervous system.

Abstract: It is possible to partially transform the silver chromate precipitate present in Golgi stained structures into lead chromate. When this partial replacement is followed by a treatment in a solution containing thiosulphate ions, only lead chromate is left in the tissue. This results in a depleted impregnation of the originally Golgi stained structures without fading of their borderlines. The tissue is then embedded in Araldite. Prior to ultramicrotomy, nerve cells and other structures can be identified under incident light microscopy. When studied with the electron microscope, they may reveal a relatively preserved cytoplasm within which organelles can be recognized.

Instantaneous adaptative delta modulation system

Abstract: An instantaneous adaptive delta modulation system including a modulator and a demodulator. The modulator comprises a comparator having a first input connected to receive an analog signal, a second input adapted for connection to an integrator located in the conventional feedback loop of the delta modulator, and a shift register connected to the output of the comparator and adapted to store the digits generated at the output of the comparator at sampling time T0 and the digits generated at sampling times T 1 and T 2. A binary up and down counter is connected to the shift register through a control circuit which makes the decision as to whether an up count, a down count, or no count at all is required. The output of the counter is applied to a decoder for converting the binary outputs of the up and down counter into a number of outputs. An amplifier having a corresponding number of values of gain is connected to the outputs of the decoder and is thus responsive to the level of the up and down counter for providing a predetermined gain into the feedback loop of the delta modulator. The integrator is connected to the output of the amplifier and its output is connected to the comparator which compares the output signal of the integrator with the input analog signal and generates a signal depending upon the difference between the two signals. The demodulator is similar to the modulator except that the input signal is fed directly to the shift register and that the output of the integrator is fed to a low-pass filter.

The rat isolated colon as a specific assay organ for angiotensin.

Abstract: 1. The antagonism of the contractile effects of prostaglandins F2α and E2 by polyphloretin phosphate (PPP) was studied on the rat isolated colon. 2. PPP (20 μg/ml) was found to reduce the myotropic action of angiotensin I (10 ng/ml) and II (0·3 ng/ml) whereas larger doses of both agents were not influenced. 3. It is concluded that when a mixture of antagonists is used, including PPP, the rat isolated colon can be used to assay angiotensin with accuracy and specificity. The addition of 8-L-ala-ATII affords a further test of specificity.

Electron microscopic studies on the pars intermedia in normal and in mice with hereditary nephrogenic diabetes insipidus.

Abstract: The ultrastructure of the pars intermedia (PI) of the normal VII +/+ and hereditary nephrogenic diabetes inspidus DI Os/+ mice has been studied with particular reference to the morphology of the glandular cells and their innervation. Four types of cells were observed in both the genotypes of mice, 1) the light glandular cell, 2) the dark cell, 3) a type of cell similar to ependymal cells and 4) a small percentage of typical ACTH cells, observed mostly on the PI border of the cleft and rarely in the centre of PI. The predominant light glandular cells contain mainly two types of membrane bound granules: 1) electron dense core granules, which measure 1500–2500 A and 2) electron lucent vesicles, which measure 3000–4000 A in diameter. Granules of intermediate size with various density are also present in both types of mice. The electron dense core granules are predominant in DI Os/+ mice, whereas, electron lucent vesicles are predominant in the normal VII +/+ mice. Similar uniform size membrane bound electron dense granules have been observed in ACTH cells of PI and pars distalis. From earlier experimental evidences and the present observations, it is concluded that the dense core granules in PI may be synthesizing ACTH or ACTH-like substance. It is also discussed that these dense core granules may further mature and give rise to MSH in the form of electron lucent vesicles. If it is so, PI light glandular cells may have dual functions, of producing MSH and ACTH. One of the functions of ependymal-like cells, may be the transport of PI secretion. Three types of nerve endings are observed throughout the PI, making synaptic contact with the predominant cell type. The innervation is more in DI Os/+ mice than in normal mice. The classification of these nerves is according to Bargmann and co-workers 1) peptidergic neurosecretory fibers, contain mainly membrane bound dense core granules, measuring 1200 to 1800 A, and are the classic neurosecretory granules; 2) adrenergic fibers, measuring 700–900 A; 3) cholinergic fibers, measuring 300–400 A. Adrenergic and cholinergic fibers are more towards the hypophysial cleft. The increased innervation, the synaptic contact, the extremely hypertrophied PI and the greater activity of its light glandular cells in the DI Os/+ mice show the PI is under the influence of the nervous system.

A new semi‐continuous dilatometer

Abstract: A new semi-continuous dilatometer which does not have the major drawbacks of the previous model was designed, constructed and tested, using the systems benzene-cyclohexane and cyclohexane-ethanol. The volumes of mixing of five systems made of n-alcohols and cyclohexanc: were determined at 25°C. Un nouveau type de dilatometre semi-continu a ete constrnit et verifie. Les principaux desavantages des dilatometres existants ont ete elimines. Les systemes benzene-cyclohexane et cyclohexane- ethanol ont ete employes pour verifier la precision de cet appareil. Les volumes de melange de cinq systemes composes de n-alcools et cyclohexane ont ete determines a 25°C.

Transitional cells in the postnatal thyroid gland of the rat.

Abstract: In two and four-week old rats three types of follicles were observed: thyroid follicles made of follicular cells and C cells; ultimobranchial follicles (or cysts) and ducts composed of lumen-bordering cells and subjacent cells; mixed follicles lined by follicular cells on one side and by lumen-bordering cells on the other. Occasionally C cells were seen in the wall of mixed follicles. On their basal side the lumen-bordering cells of mixed follicles were in direct contact with the wall of ultimobranchial ducts or cysts. In the wall of these ducts transitional cells were observed. One type had ultrastructural features of subjacent cells (i.e., hemidesmosomes) and of lumen-bordering cells (i.e., pale cytoplasm and dispersed tonofilaments). Another type of transitional cell had hemidesmosomes and a deeply indented nucleus, like subjacent cells, but had accumulated slightly distended cisternae of rough-surfaced endoplasmic reticulum and was displaying long slender microvilli, which is typical of follicular cells. A third type of cells were called “young follicular cells.” They contained slightly distended cisternal profiles of rough-surfaced endoplasmic reticulum collected in one corner of the cells and few apical vesicles. However, their cisternae were less abundant, less distended and had a more restricted distribution than those found in mature follicular cells. Hence the subjacent cells of ultimobran-chial ducts might possibly give rise to lumen-bordering cells and to some follicular cells. The latter are associated with the lumen-bordering cells in the formation of mixed follicles; at the beginning these new follicular cells seem less active than the mature follicular cells. The origin of C cells after birth is discussed.

Smooth endoplasmic reticulum proliferation in mouse enterocytes induced by fructose feeding.

Abstract: Adult male mice receiving a fructose diet show, after three days, a large proliferation of the smooth endoplasmic reticulum in the jejunal absorptive cells. This extension is a secondary stage of the trememdous increase of the glucose-6-phosphatase activity and seems to result from a crypt regulation. Glucose feeding does not provoke the same morphologic changes.

Brain Centers of Reinforcement and the Effects of Alcohol

Abstract: This chapter will report briefly on findings that preceded the observation that brain stimulation could have positive reinforcement properties, and on the questions raised by this observation. We will report as well on further investigations carried out to learn more precisely the nature of this phenomenon. Finally, we will discuss the effects of ethanol and other drugs on the brain centers.

Method and apparatus for measuring radioisotope distribution

Abstract: A tomographic detector for studying and measuring radioisotope distributions in the human body consists of detectors, used preferably with positron emitters, connected to coincidence circuits in such a way as to determine two channels of detection wherein one channel is slightly offset with reference to an axis of rotation about which the object of interest is rotated while the other channel includes the axis The method of measuring the local activity consists of first calculating the response of both channels and to subtract the counts of one channel from the counts of the other channel This method provides a sensitive detection of a given volume with a sharp cut-off and a very weak response in the surrounding region, thus providing equal lateral and depth resolution The present technique is valuable for medical section scanning and slow dynamic studies requiring the measurement of local activity

Influence of neurosecretion on the activity of median eminence and pars intermedia in hereditary nephrogenic diabetes insipidus mice with bilateral supraoptic lesions.

Abstract: The extremely hypertrophied hypothalamo-hypophysial neurosecretory system of the hereditary nephrogenic diabetes insipidus (DI Os/+) mice, shows distinctly hypertrophied median eminence (ME) indicated by the hypertrophied ependymal cells, increased number of Herring bodies and a great number of neurosecretory fibers loaded with secretion converged towards blood capillaries and towards pars tuberalis. The other distinct feature of the DI Os/+ mice is the marked hypertrophy and hyperplasia of the pars intermedia (PI) infiltrated with many beaded neurosecretory fibers. The majority of the PI glandular cells are of the large light type rather than the small type, the latter being comparatively numerous in normal mice. Very often these large light glandular cells and the marginal cuboidal epithelial cells of the hypophysial cleft contain or are surrounded by AF+ granules and/or colloid.