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Biomedical subjects

M Gagnon

Publications and source records attributed to M Gagnon.

At least 91 records · Page 5Linked to original sources
PubMed1990

Evaluation of Euler's angles with a least squares method for the study of lumbar spine motion.

To analyse intervertebral movements, methods with a high level of accuracy are required. Stereoradiographic methods have been used for a number of years to describe intervertebral movements, but their major problem is to identify the same anatomical landmarks, not only on the pair of radiographs used for three-dimensional reconstruction, but also on all the pairs used to analyse the displacements. To minimize the errors due to the incorrect identification of anatomical landmarks, a least squares method to resolve the parameters of Euler's angles was validated by means of measurements made on a spine obtained from a cadaver. The accuracy of this method varied between 0.69 degrees and 0.71 degrees in rotation and between 0.28 mm and 0.77 mm in translation. In addition, this method significantly corrected the position of the anatomical landmarks. Euler's angles, used with a least squares estimate, can provide accurate and precise results.

Aged↗
PubMed1990

Taxeopody in the carpus and tarsus of Oligocene Pliohyracidae (Mammalia: Hyracoidea) and the phyletic position of hyraxes.

Recent hyracoids and elephants share a taxeopode arrangement of tarsal and carpal bones, a condition in which bones are aligned with minimal interlocking between adjacent elements. Taxeopody has often been interpreted as a synapomorphy reflecting a close phyletic link between Hyracoidea and Proboscidea, but recently it has been suggested [Fischer, M. S. (1986) Cour. Forschungsinst. Senckenberg 84, 1-132] that hyracoid taxeopody is an independent acquisition resulting from selection favoring increased midcarpal and midtarsal rotation and that Hyracoidea is actually allied with Perissodactyla. As a test of this hypothesis, isolated carpal and tarsal bones of primitive Oligocene hyracoids from the Fayum, Egypt, have been examined to determine whether these indicate a taxeopode or diplarthral carpus and tarsus. Four complete astragali from the Fayum, representing at least three taxa, show a single, slightly convex articular surface on the head for articulation with the navicular and lack a facet for the cuboid. Two complete magna representing two species have a single proximal facet for articulation with the lunar, and they lack a facet for the scaphoid. Thus, both the carpus and tarsus of Fayum hyracoids are taxeopode. Taxeopody in hyracoids cannot be attributed to selection for carpal and tarsal rotation in climbers because the Oligocene, Miocene, and Recent species show great diversity in body size and probably locomotor specializations, despite relative uniformity of structure in the carpus and tarsus. The shared taxeopody of hyracoids and proboscideans, along with other osteological characters and similarities in hemoglobin, eye lens proteins, and other molecules, all suggest that Hyracoidea belongs within Paenungulata.

Animals↗
PubMed1990

Validity of the Mini-Mental State examination as a screening instrument for cognitive impairment and dementia in French elderly community residents.

A survey was made of 2,792 subjects aged 65 and older living in the community of Gironde (South-Western France). The predictive value of the Mini-Mental state examination (MMS) as a screening instrument for the detection of cognitive impairment was tested against DSM-III criteria for dementing syndromes. Of the 2,792 subjects who consented to participate in the study, 101 met the DSM-III criteria for dementia, giving a 3.62% prevalence rate. With an MMS threshold of 24, the sensitivity was 100%, the specificity was 78%, and the positive predictive value was equal to 15%. Using the same MMS threshold, 572 subjects (85%) were false-positive for the diagnosis of dementia. A multiple logistic regression analysis revealed that age, sex, depressive symptomatology and educational level were independently correlated with false-positive cases of the MMS. Several issues are raised for using the MMS as the only screening instrument for cognitive impairment in elderly community residents.

Aged↗
PubMed1989

Catalase activity measurement with the disk flotation method.

Activity measurements of catalase are usually performed with a spectrophotometric method by monitoring the decrease of H2O2 at 240 nm. A different method presented here uses an instrument named Catalase-meter and yields flotation time data which are expressed in tenth of seconds. For the first time, solutions of catalase of different concentrations were tested simultaneously with the two methods, and the Catalase-meter's flotation data were submitted to correlation with international units calculated from spectrophotometric data. The corresponding calibration curve correlates flotation time data to international units. The r2 values thus obtained for the two calibration curves were 0.960 and 0.929, for a range of activity varying from 9.3 to 144.5 international units/ml.

Animals↗
PubMed1989

Initial factors predicting survival in patients with a spinal cord injury.

A study is presented of a prospective analysis of survival rates in 157 patients with spinal cord injury consecutively admitted to the Pellegrin Hospital (University Hospital, Bordeaux, France). There was a 20% death rate, occurring in the first three months after injury. Three independent predictors of survival in patients with spinal cord injuries (age, initial conscious level and respiratory assistance) were found by analysis of the course of the disorder.

Adolescent↗
PubMed1989

A strategy for analysing multiple risk factors with application to cervical pain syndrome.

When studying the possible effects of several factors in a given disease, two major problems arise: (1) confounding, and (2) multiplicity of tests. Frequently, in order to cope with the problem of confounding factors, models with multiple explanatory variables are used. However, the correlation structure of the variables may be such that the corresponding tests have low power: in its extreme form this situation is coined by the term "multicollinearity". As the problem of multiplicity is still relevant in these models, the interpretation of results is, in most cases, very hazardous. We propose a strategy--based on a tree structure of the variables--which provides a guide to the interpretation and controls the risk of erroneously rejecting null hypotheses. The strategy was applied to a study of cervical pain syndrome involving 990 subjects and 17 variables. Age, sex, head trauma, posture at work and psychological status were all found to be important risk factors.

Adult↗
PubMed1988

A three-dimensional digitization method to measure trunk muscle lines of action.

A method is presented to obtain lines of action of nine major trunk muscles acting on the lumbar spine. The muscles are modeled as one or several linear or curvilinear lines of action obtained by digitizing the origins and insertions of main bundles of muscles. For curvilinear lines of action, points were also digitized along the length of the bundles, and a curve-fitting method was used. Lines of action are displayed graphically for one embalmed cadaver. Tabulated data for unit force vectors and unit moment vectors about the L3-L4 and L4-L5 discs are also presented.

Adult↗
PubMed1988

Application of a stereoradiographic method for the study of intervertebral motion.

A technique of three-dimensional reconstruction along with a method of adjusting anatomic landmarks were used to evaluate movements of the lumbar vertebrae of living subjects. Altogether, 16 subjects took part in the experiment. Each subject was radiographed in an upright standing position, and in each of the following positions: flexion, extension, axial rotation, and lateral bending. The results of the three-dimensional reconstruction procedures and the correction of anatomic landmarks show an adequate level of accuracy for experimentation with living subjects. The mean relative displacements of lumbar vertebrae in rotation are 10 degrees of flexion, 3 degrees of extension, 5 degrees of lateral bending, and 1 degree of axial rotation.

Adult↗
PubMed1988

Prevalence and risk factors of recurrent cervical pain syndrome in a working population.

The prevalence and risk factors of recurrent cervical pain syndrome (CPS) was studied in 990 workers examined while undergoing their systematic annual visit of occupational medicine. A prevalence rate of 10.2% was obtained. Using a tree-structured logistic regression analysis, a strong association between age, sex, previous head trauma extension of the neck and strenuous muscular activity during work, and the risk of recurrent CPS was obtained. Finally, an inverse association between strenuous muscular activity during leisure time and the risk of recurrent CPS was found.

Adult↗
PubMed1988

Predictors of non-bedridden survival in dementia.

The present study examined non-bedridden survival in 105 patients diagnosed as demented (Alzheimer's disease, multi-infarct dementia, mixed dementia) in a neurological ward. Follow-up observations were made. During the first year, the cumulative mortality rate was 69% compared to a rate of 44% in the second year. The initial disability stage, as assessed by the Dementia Disability Scale, was found to be the only significant predictor of non-bedridden survival. The type of dementia, age, type of diagnosis, and post-hospitalization placement in an institution have not been found to be significant predictors of this evolution.

Adult↗
PubMed1988

Scintigraphic study of duodenal-gastric reflux in cases of primary gastropathy, chronic ulcer of the duodenal bulb, and Moynihan's disease.

There are several methods for detection of bile in the stomach, but none has proven satisfactory. It appears that the scintigraphic study with quantitation of duodenal-gastric reflux after corrections for the overlap of the stomach by the liver and bowel is more reliable, noninvasive, and physiologic. Fifty-four patients were divided into groups according to their clinical presentation; seven asymptomatic volunteers, 20 patients with duodenal-gastric reflux gastropathy (DRG), 16 patients with recurrent ulcers of the duodenal bulb (RUD), and 11 patients with Moynihan's disease. Each of the 47 dyspeptic patients underwent an endoscopic examination and a scintigraphic study with [99mTc]disofenin for detection and quantitation of duodenal-gastric reflux. Endoscopy revealed the presence of bile in the stomach of 16 out of 20 DRG and four out of 16 RUD, while ten out of 11 patients with Moynihan's disease had clear gastric juice. Most of the DRG cases (15 out of 20) and half of the RUD (eight out of 16) presented reflux greater than 1.5%, while of the 11 Moynhihan, ten presented reflux less than 1.5% and all the asymptomatic volunteer subjects less than 1%. This quantitation method allowed us to perceive clearly the low % of reflux in the "normal asymptomatic" subjects compared with the DRG-type of dyspeptic patients. Among the dyspeptic, the distinction seems more evident between the DRG type and the Moynihan type. Occasionally, the scintigraphic method permits identification of patients with slower gallbladder evacuation (eight out of 47 dyspeptic in our study), adding valuable information for the diagnostic approach to dyspeptic patients.

Adult↗