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Delisle A, Gagnon M, Sicard C. Effect of pelvic tilt on lumbar spine geometry. IEEE TRANSACTIONS ON REHABILITATION ENGINEERING : A PUBLICATION OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY 1997; 5:360-6. [PMID: 9422461 DOI: 10.1109/86.650290] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to use a noninvasive method to determine the effect of pelvic tilt on the lumbar spine geometry in the sagittal plane. Five healthy male subjects were instructed in performing active forward and backward pelvic tilt manoeuvres in the standing position. The lumbar spine geometry (severity of lordosis, pelvis and lumbar vertebrae orientations) was estimated with a lumbar spine geometric model. The voluntary backward pelvic tilt succeeded in reducing the depth of the lumbar spine curvature, but the forward tilt did not change it. Both pelvic tilt manoeuvres influenced the absolute orientations of the lower lumbar vertebrae and the relative orientations of some lumbar vertebrae. Interestingly, the L5/S1 joint showed was little affected by the pelvic tilt manoeuvres.
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Gagnon M. Box tilt and knee motions in manual lifting: two differential factors in expert and novice workers. Clin Biomech (Bristol, Avon) 1997; 12:419-428. [PMID: 11415751 DOI: 10.1016/s0268-0033(97)00060-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/1996] [Accepted: 09/26/1997] [Indexed: 02/07/2023]
Abstract
OBJECTIVE: It was the objective of this study to investigate the kinematic and kinetic effects of two specific handling factors that differentiate expert and novice workers, namely the level of knee flexion and box tilt. DESIGN: Seven inexperienced subjects were required to lift a 12-kg box in the sagittal plane using three different strategies: (1) reduced knee flexion and a backward box tilt (more typical of experts); (2) large knee flexion and a backward box tilt; (3) large knee flexion and no box tilt (more typical of novices). BACKGROUND: The lifting techniques of highly skilled workers differ substantially from those of novices but only limited information is available to compare their biomechanical differences. METHODS: The methods included dynamic segmental analyses to calculate the net moments at all body joints and a planar single-muscle equivalent to estimate compression loadings at L5/S1; total work and joint work distribution were calculated using the integration of joint power. The 3-D kinematic data were acquired with three video cameras and force data were obtained with one AMTI force platform which were synchronized with the film data. RESULTS: Box tilt reduced the load trajectory and loadings on the lower back and shoulders; a reduced knee flexion affected body posture and reduced mechanical work and loadings on all body joints. The combination of these two factors, box tilt and reduced knee flexion, showed added effects for almost all variables. CONCLUSIONS: These two factors proper to experts were, in this context, biomechanically more advantageous.
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Lipsitz LA, Morin R, Gagnon M, Kiely D, Medina A. Vasomotor instability preceding tilt-induced syncope: does respiration play a role? J Appl Physiol (1985) 1997; 83:383-90. [PMID: 9262431 DOI: 10.1152/jappl.1997.83.2.383] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This study aimed to determine whether alterations in cardiovascular dynamics before syncope are related to changes in spontaneous respiration. Fifty-two healthy subjects underwent continuous heart rate (HR), arterial blood pressure (BP), and respiratory measurements during 10-min periods of spontaneous and paced breathing (0.25 Hz) in the supine and 60 degrees head-up tilt positions. Data were evaluated by power spectrum and transfer function analyses. During tilt, 27 subjects developed syncope or presyncope and 25 remained asymptomatic. Subjects with tilt-induced syncope had significantly greater increases in low-frequency (0.04-0. 15 Hz) systolic BP, diastolic BP, and HR power during tilt than the asymptomatic subjects (P </= 0.01). This difference was present during spontaneous but not paced breathing. However, average tidal volume, respiratory rate, minute ventilation, proportion of breaths below 0.15 Hz, and low-frequency respiratory power during tilt did not differ between syncopal and nonsyncopal subjects. Transfer magnitudes between low-frequency respiration and BP, and between BP and interbeat interval, were also similar between groups. Thus vasomotor instability before syncope is not related to alterations in respiration or the cardiovagal baroreflex but may reflect oscillating central sympathetic outflow to the vasculature.
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Gravel D, Gagnon M, Plamondon A, Desjardins P. Development and application of predictive equations of maximal static moments generated by the trunk musculature. Clin Biomech (Bristol, Avon) 1997; 12:314-324. [PMID: 11415740 DOI: 10.1016/s0268-0033(97)00001-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE: To develop and apply regression equations that predict the maximal static moments generated by the extensor, axial rotator and lateral flexor muscles of the trunk as a function of forward bending angles and asymmetrical positions of the torso in human subjects. DESIGN: Using experimental data, polynomial predictive equations were developed. The equations were applied in an algorithm to estimate the maximal moment generated by individual subjects. METHODS: Three groups of male subjects participated in the evaluation of the effect of forward bending and trunk asymmetry on the static moment of the extensor, right axial rotator, and right lateral flexor muscles of the trunk, respectively. Two other groups of male subjects were evaluated to test the validity of the algorithm. During the dynamometric tests, the three-dimensional position of the trunk was determined using cinematography techniques. RESULTS: For the extensor muscles, a curvilinear increase of the maximal moment was observed with forward bending, with a slight decrease of the moment on each side of the neutral position. For the right axial rotator muscles, both forward bending and left asymmetrical position of the trunk increased the maximal moments generated by these muscles. The right lateral flexors were stronger in the standing and mid-flexion positions than in other positions. First-order, second-order and interaction terms appear in the regression equations to account for the effect of forward bending and asymmetrical positions. The regression equation for the extensors and right axial rotator muscles have R(2) coefficients (range 0.56-0.76) higher than those of the lateral flexor regression equations (range 0.09-0.12). The algorithm results in an average error of 13% in predicting the strength of extensor and axial rotator muscles of individual subjects. CONCLUSION: The results have shown that strength of the extensor and axial rotator muscles is affected by forward bending and the asymmetry of the trunk, while strength of the lateral flexor muscles is only dependent on the forward bending position. The regression equations and the corresponding algorithm are applicable for the range of positions used in the study.
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Messier C, Gagnon M, Knott V. Effect of glucose and peripheral glucose regulation on memory in the elderly. Neurobiol Aging 1997; 18:297-304. [PMID: 9263195 DOI: 10.1016/s0197-4580(97)80311-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We examined changes in cognitive performance following the intake of a glucose (50 g) or saccharin solution (50 mg) in fasted elderly male and female subjects. Glucoregulation was estimated using a recovery index that was used to categorize subjects within each sex as having poor or good recovery. Elderly males with poor recovery performed worse on the Logical Memory subtest of the Wechsler Memory Scale and on the free recall or recognition parts of a work list task. The item analysis of the Logical Memory subtest showed that male subjects with poor recovery remembered less of the last items of the paragraphs after drinking saccharin while the first items were equally remembered by both groups. Glucose improved the performance of the males with good regulation for the first seven items while the performance of males with poor regulation decreased for those items under glucose. The present study support the notion that peripheral glucoregulation can influence memory performance and that the ingestion of glucose can influence certain aspects of memory functioning.
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Abstract
The Jebel Qatrani sequence found in the Fayum region of Egypt samples the richest Paleogene mammalian fauna of Africa, including some of the earliest anthropoid primates. The paleoecology of the Fayum has been interpreted as either a woodland bushland or a lowland evergreen tropical forest, although the issue of changing ecological conditions through time has never been investigated. The Fayum fossils can be grouped into four successive and stratigraphically distinct faunal assemblages. Each of these mammalian assemblages is compared with modern mammal communities. Six communities from modern African forest habitats and six communities from woodland bushland habitats are used to produce typical models of ecological diversity. An ecological spectrum for each modern community is generated by assigning mammal species to categories of taxonomic, diet, and body size diversity. Modern forest communities have a higher diversity of rodents and primates, a high diversity of frugivores, low diversity of grazers, and show a steep gradient in body size distribution from a high diversity of small species towards a low diversity of large species. Woodland-bushland communities have a higher diversity of ungulates and carnivores, a low diversity of frugivores but a high diversity of grazers, and a more even body size distribution. Diversity spectra from the four successive Fayum fossil assemblages are compared with the models derived from the modern mammal communities. The Fayum assemblages show similarities to modern forest habitats in patterns of diet diversity and to modern woodland bushland habitats in body size diversity. More detailed analyses of taxonomic diversity suggest that the lowermost assemblages were different in ecological structure from modern habitats, while the uppermost assemblage shows strong resemblances to modern humid tropical forests.
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Rosenberg R, Gagnon M, Murphy-Gismondi P, Lock Ooi W, Kiel DP, Lipsitz LA. Factors influencing subject willingness to participate in clinical gerontologic research. AGING (MILAN, ITALY) 1996; 8:400-8. [PMID: 9061127 DOI: 10.1007/bf03339602] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To identify factors influencing willingness to participate (WTP) in clinical gerontologic research, a questionnaire containing descriptions of seven research projects with a corresponding set of questions about perceived intrusiveness (discomfort and inconvenience), stipend, and other incentive factors was sent to 1004 community-dwelling research subject registry members. There was an inverse relationship between perceived level of intrusiveness and WTP. The more intrusive the study, the greater the relative influence of a stipend on WTP. Male gender and a new experience with an opportunity to learn were independently related to WTP. Subject ratings of perceived intrusiveness for each study component were entered into a factor analysis to guide the development of a three-tier "Level of Intrusiveness" scale. Although prospective validation is necessary, the Level of Intrusiveness scale may be useful in predicting WTP, and determining when other incentives are needed to improve subject recruitment for clinical research.
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Strang D, Gagnon M, Molloy W, Bedard M, Darzins P, Etchells E, Davidson W. National survey on the attitudes of Canadian physicians towards drug-detailing by pharmaceutical representatives. ANNALS (ROYAL COLLEGE OF PHYSICIANS AND SURGEONS OF CANADA) 1996; 29:474-8. [PMID: 12380577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
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.
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Gagnon M, Plamondon A, Gravel D, Lortie M. Knee movement strategies differentiate expert from novice workers in asymmetrical manual materials handling. J Biomech 1996; 29:1445-53. [PMID: 8894925 DOI: 10.1016/0021-9290(96)84540-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
One way to generate hypotheses on appropriate handling principles is to compare the strategies of highly skilled workers (experts) with those of novice workers (novices). This study was conducted to determine whether experts differ from novices in their handling strategies and to determine the effects of these differences in joint motions and net reaction moments at the trunk (L5/S1) and knees. Six experts and five novices were compared transferring two loads (12 and 22 kg) from four different initial low positions to a standardized low position on a trolley. The external forces were obtained from two AMTI force platforms, and two 16 mm Locam cameras coupled with two mirrors were used to obtain the three-dimensional kinematic data. An inverse dynamic analysis was performed on each segment and the net reaction moments were evaluated at L5/S1 and the knees; trunk posture, knee flexion angles and feet spacings were also calculated. Results showed that both groups minimized trunk asymmetries of posture and efforts; however, the experts were characterized by reduced knee flexion (31 degrees vs 53 degrees) and total knee excursion (20 degrees vs 38 degrees), increased flexion moments (72 vs 58 Nm) but reduced extension moments (4 vs 26 Nm) and valgus moments (30 vs 54 Nm). The experts' strategies appear safer overall because they reduce trunk asymmetry, asymmetrical efforts on the knee and stress on the femoropatellar joint. Moreover, these strategies present a potential for reduced mechanical energy expenditure due to lower knee excursions and increased knee stability due to reduced knee flexion.
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85
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Brown TJ, Yu J, Gagnon M, Sharma M, MacLusky NJ. Sex differences in estrogen receptor and progestin receptor induction in the guinea pig hypothalamus and preoptic area. Brain Res 1996; 725:37-48. [PMID: 8828584 DOI: 10.1016/0006-8993(96)00241-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Quantitative in vitro autoradiography was used to determine if regional sex differences in estrogen receptor (ER) content and/or estrogen responsiveness, as indicated by an increase in progestin receptor (PR), are present in the adult guinea pig brain. Adult male and female guinea pigs were gonadectomized 1 week before subcutaneous injection of 25 micrograms estradiol benzoate (EB)/kg body wt or the sesame oil vehicle. Animals were killed by decapitation 44 h after injection. Unoccupied PRs, and unoccupied and occupied ERs, were measured in discrete brain regions by quantitative in vitro autoradiography using [3H]R5020 and [3H]estradiol as ligands, respectively. In vehicle-injected controls, a higher level of ER was found in the arcuate nucleus (ARC), dorsal medial nucleus (DMN) and ventrolateral nucleus (VLN) of females as compared to males. At 44 h after EB injection, 32-55% of the ERs were occupied; however, EB treatment caused a marked down-regulation of total receptor (calculated as occupied+ unoccupied receptor) in most of the brain regions examined, including the periventricular preoptic area (PVP), medial preoptic area (MPO), bed nucleus of the stria terminalis, paraventricular nucleus, ARC, ventrolateral hypothalamus (VLH), VLN, and DMN. In EB-treated animals, PR binding was detectable in the PVP, MPO, ARC, VLH, and VLN, with higher levels of binding observed in the PVP, MPO, and VLN of the female as compared to the male. No PR binding was observed in oil-injected control animals. These results demonstrate region-specific sex differences in ER as well as estrogen-induced regulation of progestin and ERs in the guinea pig brain. The discordance between the regional distributions of sex differences in ER and estrogen-induced PR implies that sex differences in ER and estrogen-induced PR implies that sex differences in estrogen response may not be clearly linked to a sex difference in receptor number. Instead, sex differences in response may involve differences in receptor number within specific subpopulations of estrogen target cells or may involve differences in ER dynamics.
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86
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Plamondon A, Gagnon M, Desjardins P. Validation of two 3-D segment models to calculate the net reaction forces and moments at the L(5)/S(1) joint in lifting. Clin Biomech (Bristol, Avon) 1996; 11:101-110. [PMID: 11415605 DOI: 10.1016/0268-0033(95)00043-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/1994] [Accepted: 05/25/1995] [Indexed: 02/07/2023]
Abstract
The purpose of this study was to examine the validity and sensitivity of two three-dimensional segment models to estimate the net reaction forces and moments at the L(5)/S(1) joint. The two dynamic three-dimensional multisegment models, applied to lifting activities, were a lower body model and an upper body model. Three healthy male subjects participated in this study. The asymmetrical task consisted of lifting a load of 9.6 kg in a normal speed condition and in a fast condition. Results from the two models in terms of joint reaction forces and joint reaction moments at L(5)/S(1) were compared and were then used to validate them. The correlation between the reaction moments from both models were generally above 0.95 and the root mean square (RMS) differences were generally below 10 Nm but could reach 38 Nm. Similar trends were observed in the sensitivity analysis. A proportion of the error was attributable to errors in the segment accelerations because of an increase in the RMS differences between the models with an increase in lifting speed. The use of the lower body model seemed to present some advantages over the upper body model because of the nature of the task analysed which did not require large accelerations from the lower part of the body.
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87
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Messier C, Gagnon M. Glucose regulation and cognitive functions: relation to Alzheimer's disease and diabetes. Behav Brain Res 1996; 75:1-11. [PMID: 8800646 DOI: 10.1016/0166-4328(95)00153-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Glucose has been found to improve memory in animals and humans. Animal research has revealed that glucose may improve memory through a facilitation of acetylcholine (ACh) synthesis and release in the brain. This glucose-related memory improvement has prompted research in elderly humans. These studies have shown that the memory-improving action of glucose depends on each individuals' blood glucose regulation. Based on these data, researchers have evaluated the effect of glucose on memory in patients with Alzheimer's disease (AD). Results demonstrated that glucose could improve memory in a subset of patients that had abnormalities in their blood glucose regulation. Interestingly, these alterations in blood glucose regulation were believed to depend on the severity of the disease process. Another line of investigation has focused on alterations in brain glucose metabolism. Both animal models and studies with Type II diabetic elderly patients have shown that altered glucose regulation impairs learning and memory processes. It is possible that in AD patients, hyperglycemia exerts a deleterious effect by potentiating the neuronal death produced by other pathological processes taking place such as amyloid deposition. Based on these data, it appears important to find the prevalence of altered glucoregulation at various stages of AD. Secondly, it may be of interest to determine prospectively whether altered glucoregulation is linked to a faster progression of the disease. Finally, if such a relationship is observed, the next logical step would be to determine whether AD patients could benefit from treatments aimed at normalizing blood glucose regulation and improving insulin sensitivity.
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Lacroix M, Jobin M, Latreille B, Nouchpramool K, Gagnon M. The effect of gamma irradiation on physical and nutritional quality of penaeus monodon shrimps. Radiat Phys Chem Oxf Engl 1993 1995. [DOI: 10.1016/0969-806x(95)00251-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lacroix M, Charbonneau R, Jobin M, Thibault C, Nouchpramool K, Charoen S, Gagnon M. A feasibility study of gamma irradiation on Thailand frozen shrimps (PENEAUS MONODON). Radiat Phys Chem Oxf Engl 1993 1995. [DOI: 10.1016/0969-806x(95)00252-s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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90
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Gagnon M, Plamondon A, Gravel D. Effects of symmetry and load absorption of a falling load on 3D trunk muscular moments. ERGONOMICS 1995; 38:1156-1171. [PMID: 7758444 DOI: 10.1080/00140139508925179] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
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.
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91
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Plamondon A, Gagnon M, Gravel D. Moments at the L(5)/S(1) joint during asymmetrical lifting: effects of different load trajectories and initial load positions. Clin Biomech (Bristol, Avon) 1995; 10:128-136. [PMID: 11415543 DOI: 10.1016/0268-0033(95)93702-u] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/1993] [Accepted: 02/02/1994] [Indexed: 02/07/2023]
Abstract
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.
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Benjamin S, Seek A, Tresise L, Price E, Gagnon M. Case study: paradoxical response to naltrexone treatment of self-injurious behavior. J Am Acad Child Adolesc Psychiatry 1995; 34:238-42. [PMID: 7896657 DOI: 10.1097/00004583-199502000-00020] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
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.
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93
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Mazaux JM, Dartigues JF, Letenneur L, Darriet D, Wiart L, Gagnon M, Commenges D, Boller F. Visuo-spatial attention and psychomotor performance in elderly community residents: effects of age, gender, and education. J Clin Exp Neuropsychol 1995; 17:71-81. [PMID: 7608304 DOI: 10.1080/13803399508406583] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
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.
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Mohr E, Brouwers P, Claus JJ, Purdon SE, Gagnon M, Chase TN. Differential classification of dementia. Behav Neurol 1995; 8:23-30. [PMID: 24487399 DOI: 10.3233/ben-1995-8103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023] Open
Abstract
In the absence of biological markers, dementia classification remains complex both in terms of characterization as well as early detection of the presence or absence of dementing symptoms, particularly in diseases with possible secondary dementia. An empirical, statistical approach using neuropsychological measures was therefore developed to distinguish demented from non-demented patients and to identify differential patterns of cognitive dysfunction in neurodegenerative disease. Age-scaled neurobehavioral test results (Wechsler Adult Intelligence Scale-Revised and Wechsler Memory Scale) from Alzheimer's (AD) and Huntington's (HD) patients, matched for intellectual disability, as well as normal controls were used to derive a classification formula. Stepwise discriminant analysis accurately (99% correct) distinguished controls from demented patients, and separated the two patient groups (79% correct). Variables discriminating between HD and AD patient groups consisted of complex psychomotor tasks, visuospatial function, attention and memory. The reliability of the classification formula was demonstrated with a new, independent sample of AD and HD patients which yielded virtually identical results (classification accuracy for dementia: 96%; AD versus HD: 78%). To validate the formula, the discriminant function was applied to Parkinson's (PD) patients, 38% of whom were classified as demented. The validity of the classification was demonstrated by significant PD subgroup differences on measures of dementia not included in the discriminant function. Moreover, a majority of demented PD patients (65%) were classified as having an HD-like pattern of cognitive deficits, in line with previous reports of the subcortical nature of PD dementia. This approach may thus be useful in classifying presence or absence of dementia and in discriminating between dementia subtypes in cases of secondary or coincidental dementia.
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95
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Lipsitz LA, Nakajima I, Gagnon M, Hirayama T, Connelly CM, Izumo H, Hirayama T. Muscle strength and fall rates among residents of Japanese and American nursing homes: an International Cross-Cultural Study. J Am Geriatr Soc 1994; 42:953-9. [PMID: 8064103 DOI: 10.1111/j.1532-5415.1994.tb06586.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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.
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Gagnon M, Côte J, Milot J, Turcotte H, Boulet LP. Comparative safety and efficacy of single or twice daily administration of inhaled beclomethasone in moderate asthma. Chest 1994; 105:1732-7. [PMID: 8205868 DOI: 10.1378/chest.105.6.1732] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
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.
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Lovasik JV, Gagnon M, Kergoat H. 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. Surv Ophthalmol 1994; 38 Suppl:S35-51. [PMID: 7940147 DOI: 10.1016/0039-6257(94)90045-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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.
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Plamondon A, Gagnon M, Gravel D. Moments at the L5/S1 joint in four dynamic lifting conditions. J Biomech 1994. [DOI: 10.1016/0021-9290(94)91112-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gagnon M, Dartigues JF, Mazaux JM, Dequae L, Letenneur L, Giroire JM, Barberger-Gateau P. Self-reported memory complaints and memory performance in elderly French community residents: results of the PAQUID Research Program. Neuroepidemiology 1994; 13:145-54. [PMID: 8090256 DOI: 10.1159/000110373] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
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.
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Gagnon M, de Medeiros J. The present model of legislation on food irradiation needs to be changed. Radiat Phys Chem Oxf Engl 1993 1993. [DOI: 10.1016/0969-806x(93)90392-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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