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Biomedical subjects

R Lefrançois

Publications and source records attributed to R Lefrançois.

At least 19 recordsLinked to original sources
PubMed2003

A medical needle drive for the study of interstitial implant mechanics.

We describe the construction and test performance of a computer-controlled medical needle drive. The drive represents one facet of a larger project whose aim is to investigate experimentally the mechanics of needle introduction in radioactive 'seed' prostate implants, with a view to identifying ways of making incremental improvements in needle placement accuracy. It is capable of mimicking a range of motions imparted to a needle by a clinical practitioner, and of monitoring the compressive force at the needle tip in real time via an in-line load cell. Tests involving driving needles into porcine gelatin samples using a variety of velocity profiles confirm intended operation. The drive will permit us to introduce needles in a controlled and reproducible manner into a realistic prostate phantom currently being designed.

Animals↗
PubMed2000

Stressful life events and psychological distress of the very old: does social support have a moderating effect?

The purpose of this paper was to examine whether social support has a moderating effect on the relationship between exposure to stressful life events and psychological distress. To test this, 224 men and women aged 81-86 were sampled from two municipal regional counties: Sherbrooke (and vicinity) and Trois-Rivières, in the Province of Quebec, Canada. The French version of the Geriatric Scale of Recent Life Events, the Psychiatric Symptom Index, and the Social Provision Scale were used. Multiple regression analyses revealed that social support did not cancel out the deleterious effect of life events on the outcome measure. The negative aspect of social interaction may explain why social support did not have a protective effect. Also, social isolation resulting from psychological distress could reduce the opportunity for instrumental help and emotional support.

Journal Article↗
PubMed2000

[Incidence of the onset of disability and recovery of functional autonomy among the very old after one year].

BACKGROUND: This article measures the survival rate and explores the changes in functional autonomy among both men and women over a one-year period in a sample of 272 subjects aged 80-85. METHODS: Data were taken from the Quebec Longitudinal Study on Aging, a multi-cohort prospective study focusing on health and quality of life. The sample comprises two sub-groups, namely disabled and autonomous subjects. Eligible participants were selected from the Quebec Health Insurance Plan (QHIP) file. However, to obtain the required number of participants, the sample was completed from eligible subjects who volunteered in response to TV, billboard and newspaper advertising about the project. The Functional Autonomy Measurement System (SMAF) was used to assess disability. The SMAF assesses functional disability in 5 domains: activities of daily living (ADL), mobility, instrumental activities (IADL), communication, and mental functioning. RESULTS: After one year, nearly 5% of the subjects had died and 72.5% were still autonomous, i.e., they had a score under 4.5 on the SMAF. The annual incidence of the onset of disability (including death, lengthy hospitalization, functional incapacities and cognitive deficits) was 20%. However, no difference was found between the sexes in regard to the risk of losing autonomy. The main areas where disability occurred among the previously autonomous subjects were, in order of importance, domestic tasks, mobility and communication. The study confirmed that it is possible to recover autonomy, even at this advanced age, particularly for women (11.2%), but less so for men (3.6%). CONCLUSION: This phenomenon of recovering functional autonomy suggests that octogenarians have a residual potential and confirms the effectiveness of preventive and curative measures and the benefits of interventions by community and family networks.

Activities of Daily Living↗
PubMed1999

Criterion validity of a new measure of self-actualization.

Many authors have questioned the validity of the major existing measures of self-actualization (the Personal Orientation Inventory, the Personal Orientation Dimensions, and the Short Index of Self-actualization), given their serious theoretical and methodological limitations. A new inventory was developed, the Measure of Actualization of Potential, and various studies were conducted to assess its theoretical and empirical content as well as its construct validity, internal consistency, and temporal reliability. The present aim was to estimate the criterion validity of the new measure using humanistic clinical psychologists' assessments as the criterion. The results show that eight clinical psychologists' rankings of 73 individuals are positively and highly correlated with the scores obtained by the same individuals on the Measure of Actualization of Potential.

Adolescent↗
PubMed1997

Exposure and risk factors among elderly drivers: a case-control study.

To study the risk factors associated with exposure, aging, and other characteristics of elderly drivers, a case-control survey of 557 licensed drivers was conducted among residents of medium-sized, small towns and rural areas in Quebec, Canada. The subjects, aged 68 and over, were selected from the database of the provincial Automobile Insurance Board. The case group was chosen on the basis of performance, either accidents or violations, during the preceding three years. Cases were matched to a control group (blank file for the last three years) on a stratification basis (age, gender, region) in the proportion of two controls for one case. The survey which was conducted through a mail questionnaire achieved a participation rate of nearly 60%. The logistic regression method was used to assess the risk (odds ratios). The results of this study reveal that risk is proportional to the frequency of daily vehicle use or annual kilometrage. The hypothesis that elderly drivers who rarely expose themselves are at more risk is thus rejected. Vulnerable subgroups were the most elderly (> 77), city or suburban residents, the unmarried, and white collars (during active life).

Accidents, Traffic↗
PubMed1981

Esophageal motility and pulmonary function in progressive systemic sclerosis.

In order to evaluate the influence of esophageal dysfunction on lung function abnormalities in progressive systemic sclerosis (PSS), we compared pulmonary function tests in 24 patients with PSS according to esophageal motility. We observed three groups of subjects with normal esophageal motility (8 cases), impaired peristalsis but normal lower esophageal sphincter (LES; 7 cases), and impaired peristalsis and LES function (9 cases). Dynamic lung compliance was significantly lower in patients with impaired peristalsis and LES function than in the two other groups, suggesting that a gastroesophageal reflux (GER) could enhance pulmonary fibrosis in PSS.

Adult↗
PubMed1980

[Effect of protein and energy intake on nitrogen metabolism of undernourished patients on continuous enteral nutrition].

Nitrogen balance, energy balance and respiratory quotient were measured in 18 undernourished patients fed with continuous enteral nutrition in order to assess the effects of: a) various levels of protein and energy intakes with a fixed diet composition; b) energy/nitrogen ratio; c) proportions of carbohydrates in energy intake. The results were the following: 1) With energy intakes from 4,880 to 8,360 kJ/m2/day (protein: 18 p. 100) nitrogen balance and net protein absorption were significantly correlated with nitrogen intake (respectively P less than 0.01 and P less than 0.001). 2) Nitrogen balance was not significantly different whether the patient received normo (energy/nitrogen = 476 kJ/g) or hypernutrition ( energy /nitrogen = 1,056 kJ/g). 3) Nitrogen balance was not different in 6 patients receiving the same energy and nitrogen intakes but 80 or 55 p. 100 carbohydrates; high carbohydrates diet induced lipid synthesis. These results confirm the value of continuous enteral nutrition to positive nitrogen balance in undernourished patients. Except when energy expenditure level is very high they do not support a policy of routinely use hypernutrition with high carbohydrates diet.

Adult↗
PubMed1980

P50 values of non smoker and smoker pregnant women.

The influence of tobacco smoke during pregnancy on haemoglobin concentration and oxygen affinity of smoker women has been studied. Fifty-nine non smoker (NSW) and forty-five smoker women (SW) were investigated during pregnancy and early puerperium. Results have shown: 1) a slight non significant increase in oxygen affinity of SW; 2) a significant decrease in oxygen affinity in SW at term and early puerperium, the same as in NSW; 3) a significant increase in haemoglobin concentration of SW at term as compared to NSW. The small modifications of oxygen affinity of SW and the increase in haemoglobin concentration at term suggest that the oxygen delivery from the maternal to the fetal blood are probably unaffected by these factors.

Female↗
PubMed1978

Pulmonary gas exchange, diffusing capacity in natives and newcomers at high altitude.

At high altitude, in resting conditions, no differences have been observed between High Altitude Natives (HAN) and acclimatized Sea Level Natives (SLN) in AaDO2, aADCO2 or venous admixture. In acclimatized SLN, AaDO2 is smaller than at sea level because of: (1) The minor effect on arterial oxygenation of the probably constant venous admixture. (2) The reduction of VA/Q inequality as shown by a smaller aADCO2. In HAN, DLCO is greater than in SLN; the contribution of DM or VC in this difference remains unsettled, mainly because of the difficulties of measurement of DM and VC in HAN suddenly exposed to acute hyperoxia. In SLN, in acute hypoxia, DLCO increased transitorily. Asynchronous mechanisms of adaptation to high altitude are evoked.

Acclimatization↗
PubMed1978

[Influence of blood hemoglobin concentration on pulmonary diffusing capacity in man].

CO transfer factor for lungs (TLCO) was measured by a steady state method in 83 subjects (haemoglobin concentration from 60 to 270 g.l-1). TLCO was related with height (T), age (A) and with logarithm of haemoglobin concentration for a non negligeable part : TLCO = 15.45 log Hb + 33.1 T -- 0.06 A -- 51.8. The interest of this relation is discussed.

Adult↗
PubMed1977

[Study of P50 and 2,3-diphosphoglycerate in 23 bronchoemphysema patients as a function of hypoxia and hemoglobin concentration].

2,3-DPG and P50 were measured in 23 patients with chronic obstructive lung disease. All patients had a chronic hypercapnia (PaCO2 greater than or equal to 45 Torr). They are shared in 3 groups, according to hemoglobin content [Hb] and hypoxia : group I(PaO2 = 48.0 +/- 2.4 Torr ; [Hb] = 15.9 +/- 0.3 g. 100 ml-1; n = 9), (M +/- 1 SE); group II (PaO2 = 46.4 +/- 5.0 Torr; [Hb] = 11.6 +/- 0.7 g. 100 m[-1; n = 7); group III(PaO2 = 61.4 +/- 2.4 Torr; [Hb] = 13.3 +/- 0.4 g. 100 ml-1; n = 7). 2,3-DPG (group I : 1.05 +/- 0.06 mole.moleHb-1; group II : 1.02 +/- 0.08; group III : 1.11 +/- 0.08) was not significantly different of 2,3-DPG value of 12 control subjects (0.96 +/- 0.04). P50 of group I (26.9 +/- 0.9 Torr) and group III patients (28.1 +/- 1.6 Torr) was not significantly different of control value of P50 (27.4 +/- 0.5 Torr). P50 of group II patients (29.6 +/- 0.8 Torr) was significantly higher than P50 control and group I values (p less than 0.05). All the patients of group II died. These results suggest that in patients with chronic obstructive lung disease : 1) P50 value is different with various clinical conditions; 2) P50 increase is a compensatory mechanism in severe hypoxemia with anemia, but is not sufficient; 3) [Hb] is the best data for clinical prognosis.

Acid-Base Equilibrium↗