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Biomedical subjects

P Gendreau

Publications and source records attributed to P Gendreau.

At least 19 recordsLinked to original sources
PubMed1994

Social reactivity and D1 dopamine receptors: studies in mice selectively bred for high and low levels of aggression.

Robust individual differences in social behavior have been obtained by selectively breeding Institute for Cancer Research mice for high and low levels of aggression. As previously shown, when paired with a non-selected group-housed partner mouse, NC900 mice exhibit isolation-induced aggression. Conversely, NC100 mice fail to attack, freezing upon social contact. Previous studies have established that NC100 mice have lower dopamine concentrations in nucleus accumbens and caudate nucleus, with increased dopamine receptor densities in these same regions. Thus, we wished to determine the effect of administration of a dopamine receptor agonist on social behavior. Mice of both lines were administered 0, 1, 3, or 10 mg/kg (SC) of the full efficacy D1 receptor agonist dihydrexidine, and their behavior was assessed in a social interaction test. Dihydrexidine reduced aggression in NC900 mice and nonagonistic approach in NC100 mice in a dose dependent manner. In both cases, this resulted from induction of a marked reactivity to mild social stimulation as measured by increases in behaviors such as escape, reflexive kicking, and vocalizations. Dihydrexidine had no systematic effect on the freezing behavior characteristic of the low-aggressive line. In independent experiments, mice were pretreated with either the D1 antagonist SCH-23390 (.1 mg/kg) or the selective D2 antagonist remoxipride (1.0 mg/kg), after which they received dihydrexidine (10 mg/kg) and were tested as above. The effects of dihydrexidine on social reactivity in mice of both lines were significantly antagonized by SCH-23390 but not attenuated by remoxipride.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1993

Predictors of axial and peripheral bone mineral density in healthy children and adolescents, with special attention to the role of puberty.

The role of various physical and lifestyle factors in determining axial bone mineral density (BMD) at the lumbar segment of the spine, as measured by dual-photon absorptiometry, and peripheral BMD at the distal third of the radius, as measured by single-photon absorptiometry, was assessed in 299 healthy white children of both sexes, aged 6 to 18 years. The BMD measurements were correlated with age, height, weight, body mass index, and pubertal status. Peripheral and axial BMD were highly correlated with age, height, weight, and pubertal stage, and more weakly with body mass index. Approximately 76% of the observed changes in peripheral BMD were accounted for by age, height, weight, and pubertal stage, with weight being the single strongest predictor. Up to 80% of the variation in axial BMD was explained by weight and pubertal stage, with pubertal stage being the strongest single predictor. After adjustment for weight, the effect of puberty on axial BMD in both sexes was greatest between middle and late puberty. These data indicate that a large amount of the observed changes on BMD is accounted for by standard measures of growth and development, which are largely genetically determined. Peripheral BMD rose steadily with age. Axial BMD increased steadily before puberty, followed by accelerated increases during puberty, beginning at 10 years of age in girls and 13 years of age in boys. A significant positive effect of dietary calcium intake on peripheral BMD and of physical activity on axial BMD indicated a potentially important impact of physical activity and calcium intake on peak bone mass.

Adolescent↗
PubMed1992

[Psychometric characteristics of the French Canadian version of a satisfaction scale for hospitalized psychiatric patients].

This paper presents the results of a content and convergent validity study of the French-Canadian version of a standardized satisfaction scale for hospitalized psychiatric patients. One hundred and twenty-two patients underwent an interview during which they completed the translated version of the Client Satisfaction Questionnaire, developed by Distephano et al, and answered open-ended questions on their satisfaction with the services they received. The results revealed strong correlations between these measures of satisfaction and a high level of internal consistency for the Distefano scale, suggesting satisfactory psychometric characteristics for this French version. As for the original questionnaire, the factorial structure yielded at least two distinct satisfaction dimensions. These results, and those of the content analysis, based on answers from the open-ended questions, helped to identify aspects mentioned by the patients but not covered by the items included in the satisfaction scales. The units' cleanliness, therapists' work and attitudes and privacy on the units are examples of these dimensions.

Adult↗
PubMed1987

Glucocorticoid receptors in chick embryos: properties and ontogeny of the nuclear renal receptor.

A putative nuclear receptor for glucocorticoids was identified in the kidney of chick embryo. This receptor was a thermolabile protein which was readily digested by proteolytic enzymes. Its sedimentation coefficient on sucrose density gradient was 3.5S and its MW approximated, according to the Svedberg formula, at 98,500 Da. Binding assays, performed with crude or purified nuclei, and nuclear extracts showed that the latter preparation was the most suitable for the binding studies since it yielded a Bmax of 8-11% with a very low nonspecific binding (1% or less). Scatchard plots performed at various days of embryogenesis revealed a single class of binding sites with an association constant (Ka) of 0.12 +/- 0.06 X 10(9) M-1 (mean +/- SD; n = 5) and a maximal binding capacity (Nmax) that rose from 3.9 +/- 1.2 fmol/micrograms DNA at Day 13 of age to 13.2 +/- 2.2 fmol/micrograms DNA at Day 16 and then rapidly fell to 1.8 +/- 1.1 fmol/micrograms DNA before hatching (means +/- SD; n = 5). Competition studies with various steroids showed that only glucocorticoids and, to a lesser degree, progesterone had an affinity for the receptor. These results demonstrate that this nuclear-binding protein had physiochemical properties similar to those attributed to other glucocorticoid receptors in target cells.

Animals↗