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Biomedical subjects

M Gagnon

Publications and source records attributed to M Gagnon.

At least 55 records · Page 3Linked to original sources
PubMed1996

Handgrip and Box Tilting Strategies in Handling: Effect on Stability and Trunk and Knee Efforts.

The purpose of this study was to evaluate the effect of four handgrip-box tilting strategies (right, left, backward, and no tilt of the box) on trunk and knee efforts, body posture, and the stability of 14 participants with limited experience in handling. The tasks consisted of transferring a low-lying box placed in front of the participant to a shelf of the same height at the participant's left. It was hypothesized that tilting the box could reduce trunk and knee efforts as well as body asymmetry, and improve stability. A tridimensional dynamic rigid body model was used to estimate the triaxial net muscular moment magnitudes at the trunk (L5/Sl) and at the knees. An approach to quantify the participants' dynamic stability was also included. Finally, 5 angles were computed to characterize body asymmetries. The results showed that tilting the box affected specific trunk efforts, but did not succeed in reducing trunk asymmetric efforts. However, the tilts were executed in a single direction, and it may be possible that combined tilts of the box could help reduce trunk asymmetric efforts. Tilting the box had little effect on knee loadings, and the left tilt strategy reduced participants' stability. This study showed the importance of considering the position of the box when assessing the risks encountered in asymmetrical handling.

Journal Article↗
PubMed1996

National survey on the attitudes of Canadian physicians towards drug-detailing by pharmaceutical representatives.

OBJECTIVE: Our objective was to study the attitudes of Canadian physicians toward product presentations by pharmaceutical representatives (PRs), the use of inducements by the pharmaceutical industry, and methods to improve the quality of prescribing information provided to physicians. DESIGN: We used a mailed survey. PARTICIPANTS: A random sample of 550 Canadian physicians in all settings was chosen. OUTCOME MEASURES: The main outcome measure was the proportion of respondents agreeing with a series of statements. RESULTS: The response rate was 262 of 525 deliverable surveys (50 per cent). Respondents had a mean of 4.2 interactions per week with PRs. Of the 262 respondents (5.8 per cent of data were incomplete), 193 (80 per cent) believed that PRs overemphasize their products' effectiveness, 108 (45 per cent) thought PRs do not present fairly the drugs' negative aspects, and 223 (92 per cent) felt that PRs have production promotion as a goal. Most, 175 (70 per cent), believe that drug-detailing affects physicians' prescribing behavior. Most, 210 (86 per cent), considered drug samples acceptable, but fewer agreed that other inducements were acceptable. Of the respondents, 183 (74 per cent) agreed that PRs should be required to use guidelines for standardized, comprehensive drug-detailing, and 165 (65 per cent) agreed that face-to-face drug-detailing by PRs using standardized guidelines would be an effective way to receive information. CONCLUSIONS: There is dissatisfaction among Canadian physicians about the quality of information provided by the pharmaceutical industry. Standardized, comprehensive guidelines would be accepted by physicians as one improvement.

Advertising↗
PubMed1995

Moments at the L(5)/S(1) joint during asymmetrical lifting: effects of different load trajectories and initial load positions.

The purpose of this study was to examine the reaction moments at L(5)/S(1) about the three orthogonal orthopaedic axes on the trunk when performing asymmetrical lifting tasks under six experimental conditions. The first three conditions were three lifting modes referring to different load trajectories (diagonal, extension then twisting, twisting then extension). The next three conditions were three lifts referring to different initial load positions (90 degrees, 45 degrees, 0 degrees ). Ten male volunteers (mean age 23.4 years) participated in the study. The mass of the load was 11.6 kg and two shelves were used: a low shelf of 22 cm from which the load was removed and a high shelf of 80 cm onto which the load was laid down following the manoeuvre. A dynamic 3D multisegment model was used to compute spinal loadings. The maximum reaction moments generated at the joint for the three load trajectories and for the three initial load positions were approximately of the same magnitude. On the other hand, significant differences were observed in the trunk orientation when the maximal moment was generated. Symmetrical trunk positions appeared to be more advantageous because of the reduction in the capability of maximal extension force in asymmetric trunk posture. A possible alternative for avoiding excessive stress on the back in asymmetric trunk posture may be to keep the shoulders parallel to the ground. RELEVANCE: Three-dimensional studies of the resulting moments at L(5)/S(1) when performing lifting activities are not common, particularly when the tasks include muscular exertions in trunk flexion combined with either twisting or lateral bending. This type of analysis is particularly important since asymmetries have been identified as risk factors for low back disorders. The knowledge of reaction moments in relation to postures are essential to understand the mechanism of low back pain.

Journal Article↗
PubMed1995

Effects of symmetry and load absorption of a falling load on 3D trunk muscular moments.

Some epidemiological data have suggested that many physical causes of low back pain such as bending and twisting were, in fact, sudden maximal efforts incidentally carried out at the moment of accident. Sudden loading conditions may be encountered in several circumstances, one of them being the recuperation of a falling load. Such conditions are more likely to occur in conditions of trunk asymmetry. The objective of this study was to determine spinal loadings associated with the reception of a falling box symmetrically and asymmetrically for two mechanisms of load absorption, one limited to the elbows and the other including full absorption with the elbows and lower limbs. It was hypothesized that asymmetrical receptions would be more strenuous for the spine; it was further hypothesized that the full absorption to decelerate the load might be more efficient in reducing the strain in the trunk muscular moments. Nine students in physical education with limited experience in manual materials handling were the subjects of the study. The tasks consisted of receiving a 6.6 kg load falling from a height of 50 cm above the flexed forearms when in a standing position. The subjects were tested with two AMTI force plates and two Locam cameras coupled with two mirrors; dynamic 3D multi-segment models were constructed and the net muscular moments as well as the angular velocities of the trunk relative to pelvis were determined about the three orthogonal axes of the trunk at L5/S1, in twisting, lateral bending, and flexion/extension. The dependent variables included maximal moments, maximal rates of loading for these moments, and the integration of these moments. Statistical analyses were performed to test the main effects of symmetry and absorption and their interaction. The results showed that asymmetrical conditions impose supplementary muscular exertions for trunk muscles, especially the trunk extensors and lateral flexors. Contrary to the proposed hypothesis, full absorption as used in the present study was a condition leading to considerably larger muscular exertions, especially for the loading rates. Thus it was concluded that the process of training for load absorption is essential to effectively decrease the risks of injuries. This factor would merit full consideration in future studies.

Absorption↗
PubMed1995

Visuo-spatial attention and psychomotor performance in elderly community residents: effects of age, gender, and education.

In cross-sectional analysis of 1,799 subjects of the Paquid Research Program, an epidemiological study on brain aging conducted in the Bordeaux area (France), we have studied the effects of age, gender, and education level on psychometric tests requiring visuo-spatial focused attention and psychomotor performance. Although previous studies suggest that normal aging produces no significant change in focused attention, we did observe lower attentional abilities and lower speed of execution with increasing age. Female gender and low education level were also related to poorer attention and psychomotor performance. As the effects of these individual factors are difficult to disentangle from each other on the small samples of subjects used in group studies, epidemiological surveys seem useful to provide a better understanding of the neuropsychology of aging.

Age Factors↗
PubMed1995

Case study: paradoxical response to naltrexone treatment of self-injurious behavior.

Opioid receptor antagonists have been studied in the management of self-injurious behavior (SIB) in developmentally disabled individuals. The authors present a case of a severely retarded, autistic man whose SIB increased dramatically during a trial of naltrexone. A paradoxical increase in SIB, attributed to the extinction burst phenomenon during the initial period of nonreward, is known to occur during treatment with naloxone, a short-acting parenteral opioid antagonist. It has only once been reported during treatment with naltrexone, a long-acting orally administered agent. Opioid analgesic effects and learning theory can explain both increases and decreases in SIB after opioid blockade.

Adult↗
PubMed1994

A novel noninvasive videographic method for quantifying changes in the chromaticity of the optic nerve head with changes in the intraocular pressure, pulsatile choroidal blood flow and visual neural function in humans.

Vision loss in glaucoma may be due to the compressive effects of the intraocular pressure (IOP) on the ganglion cell axons, impaired blood flow to the optic nerve, or some combination of these two factors. While reducing the IOP may preserve vision in patients with elevated IOP, not all patients experience longterm benefits from this therapeutic approach. The survival of ganglion cells may be more dependent upon the degree of vascular perfusion of the optic nerve head (ONH). In this report we present some preliminary data on a new noninvasive videographic technique for elaborating the capacity of the ONH vasculature to maintain perfusion constancy in the presence of transient elevations of the IOP and reductions of the ocular perfusion pressure (OPP). Shortterm, stepwise reductions of the OPP in the test eye of visually normal subjects (n = 5) systematically altered both the chromaticity (hue, saturation, brightness) of the ONH and the pulsatile ocular blood flow (POBF) in the choroid. Similar transient reductions in the OPP were seen to impair normal retinal physiology, as indicated by a significant attenuation of the bilateral pattern-reversal electroretinograms (pERGs) in visually normal subjects (n = 7). This technique was also used to reveal spontaneous rhythmical variations in the ONH chromaticity which were linked to the cardiac pulse rate. This so-called "chromatic pulse" of the ONH offers potential as a useful clinical index for evaluating the vascular perfusion of the ONH. The diagnostic and prognostic potential of dynamic digital imaging for the detection of abnormal hemodynamics in the ONH is discussed.

Blood Flow Velocity↗
PubMed1994

Muscle strength and fall rates among residents of Japanese and American nursing homes: an International Cross-Cultural Study.

OBJECTIVE: In Western society, aging if often associated with adoption of a sedentary lifestyle and associated disuse muscle atrophy and weakness. Recent studies suggest a relationship between quadriceps muscle weakness and falls in elderly residents of US nursing homes (NHs). We hypothesized that fall rates would be lower in Japanese NHs, where lifestyle differences such as squatting to toilet or sleeping on the floor may maintain quadriceps strength and result in fewer falls. Therefore, we examined the relationships between falls, muscle strength, lifestyle, and other clinical characteristics in residents of a Japanese and an American NH. DESIGN: Cross-culture, prospective, cohort study. MEASUREMENTS: We evaluated disease histories and current medications, quadriceps strength, and mobility of ambulatory American (n = 76) and Japanese (n = 89) NH residents, then followed these residents prospectively for the development of falls. Project staff from both sites trained together to assure uniform data ascertainment. MAIN RESULTS: During a 6-month follow-up period, fall rates were nearly 4-fold higher in the American than in the Japanese residents (49% vs 13%, respectively; P < 0.0001). In the American sample, fall rates declined with increasing muscle strength, while in Japan there was no relationship between fall rates and quadriceps strength. Residents also differed in number of medical diagnoses and use of medications, which were greater among American residents. The Japanese had slower gait speeds. Very few Japanese residents practiced squatting behaviors while living in the NH. CONCLUSIONS: The relationship between muscle weakness and falls is probably modified by multiple characteristics of the individual, their culture, and their environment. Information from cross-cultural studies may provide new insights into effective fall prevention strategies for nursing home residents.

Accidental Falls↗
PubMed1994

Self-reported memory complaints and memory performance in elderly French community residents: results of the PAQUID Research Program.

An epidemiological survey of self-reported memory complaints and memory performance [assessed with Benton's visual-retention test (BVRT) and the Wechsler paired-associates test (WPAT)] was undertaken in a community sample of 2,726 noninstitutionalized subjects aged 65 and over living in Gironde (southwestern France). A significant relationship was observed between the presence of self-reported memory problems and lower performance on the BVRT and the WPAT. However, beyond this relationship, there was significant discordance between the two evaluations, explained in part by the fact that the correlates of memory functioning were not related with similar strength to self reports and to actual performance. In general, females and subjects who scored above the depressive symptomatology threshold reported more problems, while lower performances were related to older age and low educational level. The discordance between self reports and actual performance may suggest anosognosia of mild memory deficits and could possibly be a predictor of future intellectual deterioration.

Aged↗
PubMed1994

Comparative safety and efficacy of single or twice daily administration of inhaled beclomethasone in moderate asthma.

OBJECTIVES: In the treatment of stable mild to moderate asthma, twice-daily administration of inhaled steroids may allow adequate control of the asthma; however, comparisons of the efficacy of once- or twice-daily administration brought contradictory results. This study is a randomized, double-blind crossover trial, set to determine if inhaled beclomethasone dipropionate given once daily in the late afternoon or at bedtime can be as effective as a twice-daily regimen in the treatment of moderate asthma. DESIGN: Subjects were randomly assigned to 3 different dosing regimens of inhaled beclomethasone: (1) regimen A, a twice-daily dose of 500 micrograms in the morning and at bedtime; (2) regimen B, a single dose of 1,000 micrograms in the late afternoon; and (3) regimen C, a single dose of 1,000 micrograms at bedtime. PATIENTS AND PARTICIPANTS: Enrolled in the study were 42 subjects who required 500 micrograms of inhaled beclomethasone dipropionate twice daily to control symptoms of asthma and to minimize use of beta 2-adrenergic agonists, according to criteria suggested in a recent international consensus on asthma therapy. Prior to receiving therapy with inhaled steroids, all of these patients either had chronic symptoms of asthma that required administration of a short-acting beta 2-agonist at least twice per day, or had nocturnal asthma symptoms at least once per week. THERAPY: After a 2-week baseline evaluation, each subject was given the 3 treatment regimens in randomized order, each for a period of 4 weeks. Subjects were asked to record daily symptoms of asthma and peak expiratory flows in the morning and evening. At the end of each treatment period, spirometric data and airway responsiveness to methacholine were measured. MEASUREMENTS AND RESULTS: Thirty-seven subjects completed the study. No significant difference was found among the 3 treatment regimens for asthma symptoms, FEV1, the provocative concentration of methacholine causing a 20 percent decrease in the FEV1 (PC20) (geometric means, 1.41, 1.09, and 1.09 mg/ml), and mean morning and evening peak expiratory flow rates (PEFR). The plasma cortisol level and the adrenocorticotropic hormone (ACTH) response were not significantly different among treatments, nor were side effects, which were minimal. CONCLUSION: In moderate asthma controlled with a twice-daily dose of inhaled beclomethasone, a single total daily dose administered in the late afternoon or in the evening provides as good control of asthma for 2 months.

Administration, Inhalation↗
PubMed1993

Pivoting with the load. An alternative for protecting the back in asymmetrical lifting.

The purpose of this study was to examine different lifting conditions with combined flexion and twisting of the trunk relative to the pelvis (full twist and half-twist techniques) and to compare them to a situation using feet pivoting with minimization of trunk motions relative to the pelvis. Nine subjects with limited experience were tested with two force platforms and two 16-mm cameras coupled with two mirrors; dynamic three-dimensional multisegment models were constructed and the net muscular moments as well as the angular velocities of the trunk relative to pelvis were determined about the three orthogonal orthopaedic axes of the trunk at L5-S1 in flexion-extension, lateral bending, and twisting. The results showed that pivoting required larger extension moments but considerably smaller twisting moments and that these moments were exerted from a safer trunk posture. Pivoting appears to be a good compromise to avoid or minimize complex trunk postures and loadings.

Adult↗
PubMed1993

A geometric model of the lumbar spine in the sagittal plane.

This article describes a geometric model using the skin profile and five anthropometric measurements to estimate the position of S1, T12, and all lumbar vertebrae for all postures assumed in the sagittal plane. This method involves a normalization process by which different skin profiles can be compared between postures and individuals. The skin profile is transformed by taking the differences with the lumbar spine into consideration. The model was developed and validated with 20 and 7 subjects, respectively. An error analysis shows an adequate level of accuracy for the absolute (1.68-1.82 cm) and relative (0.32-0.54 cm) linear positions of vertebrae as well as their absolute (2.6-6.7 degrees) and relative (1.4-3.6 degrees) angular positions except for T12; however, the validity of the model was limited to specific angular motions in flexion for the pelvis (12 +/- 3%), the entire lumbar spine (14 +/- 13%) and the intervertebral motion of L4/L5 (13 +/- 10%). The data obtained are very useful, especially in models designed to evaluate loadings on the lumbar spine.

Adult↗
PubMed1992

Principal lifetime occupation and cognitive impairment in a French elderly cohort (Paquid).

The purpose of the present study was to examine the relation between principal lifetime occupation and cognitive performance with the initial data collected (1988-1989) in a cohort of 3,777 community residents of the area of Bordeaux, France, aged 65 years and older. Subjects were considered as cognitively impaired if they scored under 24 on the French version of the mini-mental state examination. Cognitive impairment was found to vary significantly across the different occupational categories. Results of the logistic regression show that age, sex, and educational level are significantly related to cognitive impairment. Moreover, after controlling for these and other covariates, farmworkers (odds ratio (OR) = 6.1, 95% confidence interval (CI) 3.3-11.4), farm managers (OR = 2.9, 95% CI 1.6-5.1), domestic service employees (OR = 2.8, 95% CI 1.5-5.1), and blue-collar workers (OR = 2.5, 95% CI 1.4-4.4) had a higher risk of cognitive impairment than did subjects who had an intellectual occupation. Follow-up of the cohort will permit precise determination of the role of principal lifetime occupation in subsequent cognitive deterioration. Occupational status should be taken into consideration when studying brain aging.

Age Factors↗
PubMed1992

The influence of dynamic factors on triaxial net muscular moments at the L5/S1 joint during asymmetrical lifting and lowering.

Asymmetrical lifting and lowering are predominant activities in the workplace. Mechanical causes are suggested for many back injuries and the dynamic conditions within which spine loading occurs are related to spine loading increase. More data on tridimensional biomechanical lumbar spine loading during asymmetrical lifting and lowering are needed. A tridimensional dynamic multisegment model was developed to compute spinal loading for asymmetrical box-handling situations. The tridimensional positions of the anatomical markers were generated by a direct linear transformation algorithm adapted for the processing of data from two real and two virtual views (mirrors). Two force platforms measured the external forces. Five male subjects performed three variations (slow, fast and accelerated) of asymmetric lifting and two variations (slow and fast) of asymmetric lowering. The torsional, extension/flexion and lateral bending net muscular moments at the L5/S1 joint were computed and peak values selected for statistical analysis. For the lifting task, the fast and accelerated conditions showed significant increases over the slow condition for torsion, extension/flexion and lateral-bending moments. The accelerated condition also showed significant increases over the fast condition for extension. A comparison between lifting and lowering tasks showed equivalent loadings for torsion and extension. The moments were compared to average maximal values measured on equivalent male subject populations by isokinetic dynamometry. This showed torsional and extension values of 30 and 83% of the maximal possible subject capacity, respectively. These results demonstrated that dynamic factors do influence the load on the spine and highlighted the influence of both lifting and lowering on the loading of the spine. This suggested that for a more complete analysis of asymmetrical handling, the maximal velocity and acceleration produced during lifting should be included.

Adult↗
PubMed1992

Depressive symptomatology and cognitive functioning: an epidemiological survey in an elderly community sample in France.

As part of a 5-year, prospective, epidemiological survey of normal and pathological ageing, this cross-sectional analysis examines the relationship between depressive symptomatology (CES-D) and cognitive functioning (MMS) in a community sample of 2792 non-institutionalized persons (age greater than or equal to 65) living in Southwest France. Of the sample, 13.4%, report depressive symptoms above the cut-off. A significant association was found between CES-D and MMS scores, but after adjusting for age, living arrangements, and especially functional limitations, the relationship remained strong only for women.

Activities of Daily Living↗
PubMed1992

Biomechanical exploration on dynamic modes of lifting.

Whatever the lifting method used, dynamic factors appear to have an effect on the safe realization of movement, and NIOSH guidelines recommend smooth lifting with no sudden acceleration effects. On the other hand, inertial forces may play an important role in the process of transfer of momentum to the load. The direction by which these inertial forces may affect the loadings on body structures and processes of energy transfers cannot be determined a priori. A biomechanical experiment was performed to examine if there were differences in the execution processes between a slow-continuous lift and an accelerated-continuous lift, and also between accelerated lifts either executed continuously or interrupted with a pause. The lifts were executed from a height of 15 cm to a height of 185 cm above the head and with two different loads (6.4 and 11.6 kg). Five experienced workers in manual materials handling were used as subjects. Films and force platforms recordings supplied the data; dynamic segmental analyses were performed to calculate net muscular moments at each joint; a planar single-muscle equivalent was used to estimate compression loadings at L5/S1; total mechanical work, joint work distribution, and energy transfers were determined from a kinetic approach based on the integration of joint power as a function of time. Analyses of variance with repeated measures were applied to the three treatments. The results showed that joint muscular moments, spinal loadings, mechanical work, and muscular utilization ratios were generally increased by the presence of acceleration without inducing benefits of improved energy transfers; therefore slower lifts with reduced acceleration may be safer when handling moderately heavy loads. The maximum values of kinematic and kinetic factors were generally not affected by the pause, but the occurrence of jerks in the movement (acceleration, ground forces, and muscular moments) suggests that the pause may not be indicated when considering total exposure to muscular exertion. Full consideration should be given to the dynamics of motion when assessing risk factors in working tasks.

Acceleration↗
PubMed1992

Health measures correlates in a French elderly community population: the PAQUID study.

PAQUID is an epidemiologic prospective study of mental and functional aging. A sample of 4,050 community-dwelling individuals, aged 65 and over, was randomly selected from electoral lists of 37 parishes of Gironde after stratification by age, sex, and size of urban unit; 68.9 percent agreed to participate. Baseline information was obtained from a one-hour home interview. Health measures included ADL, IADL, mobility, Rosow scale, and two subjective health assessments. Depressive symptomatology was assessed by the CES-D scale and cognitive functioning by Folstein's MMS. Dependence rates vary from 9.7 percent to 71.9 percent according to the indicator under consideration. Cross-sectional correlations with dependence are significant for age, sex, education, rural setting, joint pain, dyspnea, hearing and visual impairment, MMS score, and depression. In logistic regressions, only dyspnea, MMS score, and depression are always significantly correlated with dependence, whichever the indicator.

Activities of Daily Living↗