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Biomedical subjects

M Fleury

Publications and source records attributed to M Fleury.

At least 73 records · Page 4Linked to original sources
PubMed1991

Kinematics of aiming in direction and amplitude: a developmental study.

The patterns of aimed movements to visual targets were analyzed in children aged 6, 8 and 10. Tasks with direction and/or amplitude requirements were used. The tasks were performed both with and without vision. Peak velocity, acceleration and deceleration and their relative temporal occurrence were evaluated. Overall, the 6- and 10-year-olds exhibited higher peak velocity and acceleration when performing the pure directional task than when performing tasks with an amplitude or stopping requirement. On the contrary, 8-year-olds showed similar peak acceleration and velocity across all three tasks. Similarly, when performing the pure directional task, the 6- and 10-year-olds reached their peak velocity and acceleration relatively later in time than the 8-year-olds. Vision of movement increased the peak velocity in all experimental tasks and peak acceleration was increased only in the pure directional task. Thus, movement kinematics varied according to the task requirements and age. Eight-year-olds showed greater propensity to feedback control in all tasks, suggesting an over-inhibition in their approach patterns, whereas 10-year-olds tended to use feedforward processes, with a shortened deceleration phase.

Child↗
PubMed1990

Timing and accuracy of visually directed movements in children: control of direction and amplitude components.

The reaction times (RTs), movement times (MTs), and final accuracy of hand movements directed towards visual goals were measured in 6-, 8-, and 10-year-old children, using tasks in which direction and amplitude components of movement were distinctly required. The tasks were performed with and without visual feedback of the limb. RTs decreased with age, and were shorter in directional than in amplitude task, in all ages. MTs were the longest at age 8 in both tasks, equally short at ages 6 and 10 in the directional task, the shortest at age 10, and intermediate at age 6, when amplitude had to be regulated. In the amplitude task, the target distance generally affected MTs under both visual conditions, but to a lower degree at age 10 than in the two younger groups. Movement accuracy, which was in all cases higher with visual feedback, showed different developmental trends among the two spatial components: directional accuracy was not different among the three groups of age, whereas amplitude accuracy showed a nonmonotonic development in the nonvisual condition, with an increase between age 6 and age 10, and the lowest level at age 8. In the visual condition, amplitude accuracy did not change with age. The specification of direction seems therefore to predominantly load the preparatory stage of the response. Amplitude specification seems to be more dependent on on-going regulations and to undergo a longer and more complex development, with a critical period around age 8 when a greater propensity for a feedback-based control appears on the two components. With increasing age, amplitude tends to be specific to a greater extent by a feedforward process.

Attention↗
PubMed1990

[Metabolic fatigue and the performance of visual tasks].

The aim of this study was to analyse the effects of different types of metabolic fatigue, induced by anaerobic alactacid, anaerobic lactacid, sub-maximal aerobic, and maximal aerobic efforts, on the performance of a sensory task (peripheral threshold detection), a sensory-motor task (coincidence-anticipation), and a cognitive task (recall in central vision). Each of three experimental groups performed one of the above-mentioned tasks under all types of fatigue. Running bouts on a treadmill were used to induce the different types of fatigue. Results show that performance in peripheral vision improves with all types of effort. For coincidence-anticipation, only constant error is affected by anaerobic alactacid and maximal aerobic efforts; the former producing a change in behavior from lateness to anticipation, whereas the latter significantly reduces lateness. Finally, performance in the cognitive task is significantly disturbed by the maximal aerobic exercise. It is suggested that, while sensory and adaptive behaviors improve with previous physical work, cognitive behavior is handicapped by highly demanding activities, that is, activities requiring aerobic maximal efforts.

Adult↗
PubMed1989

[Efficacy of uvulopalatopharyngoplasty (UPPP) and modifications in sleep structure in the sleep apnea syndrome (SAS)].

Thirty-four patients (32 male, 2 female; mean age 53 +/- 7 years) with confirmed sleep apnea syndrome (SAS) were studied before and after uvulopalatopharyngoplasty (UPPP). Clinical symptoms were tiredness, excessive daytime sleepiness and snoring. All patients were overweight. Patients underwent a thorough physical and oropharyngeal examination and polysomnography before and 3 months after surgery. On the basis of post-operative results, patients are divided into 3 groups: --group 1: 16 cured patients: apnea index (A.I./h) 38 +/- 17 before and 4.4 +/- 4 apneas/h sleep after surgery. Improved nocturnal hypoxemia: mean minimum oxyhemoglobin saturation (SAO2) before and after UPPP in NREM sleep 83 +/- 4% v. 90 +/- 4% in REM sleep 76 +/- 11% v. 85 +/- 7%. Uninterrupted sleep is restored; --group 2: 8 improved patients: A.I./h of 64 +/- 11 before and 20 +/- 6 after UPPP: improved nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 74 +/- 10% before and 86 +/- 6% after UPPP: in REM sleep 59 +/- 9% before and 79 +/- 6% after UPPP, lower amount and percentage of fragmented sleep; --group 3: 10 non-improved patients: A.I./h unchanged 55 +/- 22% before and 50 +/- 20% after UPPP. Persistent nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 76 +/- 13 before and 81 +/- 12% after UPPP: in REM sleep 63 +/- 16% before and 65 +/- 24% after UPPP. Sleep remains fragmented. In this last group patients are more overweight and all suffer from severe SAS with greater nocturnal oxyhemoglobin desaturation. Surgical treatment by UPPP is shown to be effective for 70% of our patients. Better results are obtained when SAS is less severe and overweight less important.

Adult↗
PubMed1989

[A new case of allo-anti-LWab].

A patient admitted to hospital for hip replacement was found incompatible in pretransfusion testing due to allo-anti-LWab antibody, as well as anti-JKb, anti-E and anti-IH antibodies. The patient had a rare phenotype LW(a-b-ab-). The antibodies were acquired though pregnancy and/or transfusion. This newly discovered anti-LWab allowed us to study and emphasize the relevant serological and transfusional aspects related to incompatibility caused by "public" antibodies in association with other alloantibodies. We attempted to update the LW system in the light of Sistonen and Tippett's recent discoveries. We collected the required compatible units of blood through autologous donations and a Central Canadian Red Cross Registry for rare donors.

Aged↗
PubMed1989

[Delayed hemolytic transfusion reaction caused by an anti-U].

Delayed hemolytic transfusion reactions due to anti-U are rare, only two (2) cases having been reported in the literature. We now report a third case: a multiparous black woman without any transfusion history was admitted to hospital for severe microlytic anemia (31 g/l). The patient was group AB negative, the direct antiglobulin test was negative and an anti P1 cold allo-antibody was present in her serum. Five A, Rh negative, P2 packed red cells were cross-marched with the sample obtained at admission on January 8, 1988. She was transfused on January 8, 9, 10, 11 and 12. On the 12th of January her hemoglobin level reached 125 g/l. On January 13, the patient presented clinical signs of hemolysis and her hemoglobin fell to 60 g/l within 24 hours. On January 15, the direct antiglobulin test was positive and an antibody found in her serum was reactive with all the red cells of the commercial panel. The sample was referred to our red cell serology reference laboratory. The phenotype of the pre-transfusion sample was found to be Fy(a-b-) M, N, S-s-U-. An anti-U was detected in the eluate and the serum. The patient was transfused with two (2) units of O-P2, U-red cells obtained from the American Red Cross, Syracuse, and her hemoglobin reached 90 g/l within 48 hours. This is the third reported case of a delayed hemolytic transfusion reaction due to anti-U. This case illustrates the need to perform cross-matches with samples obtained within 48 hours of the scheduled transfusion for patients who have been transfused with blood in the preceding 3 months. Also, this case emphasises the need to recruit U negative blood donors for the Canadian rare donor file.

Anemia↗
PubMed1989

[Stability in shooting: the effect of expertise in the biathlon and in rifle shooting].

The aim of this study is to compare the body-gun stability of biathletes and rifle shooters up to the firing of a shot, when shooting in standing position. Eight subjects are tested: two experts and two novices in rifle shooting, two experts and two novices in biathlon. Electromyographic (EMG) activity of the tibialis anterior, gastrocnemius and deltoid muscles, as well as rifle oscillation and centre-of-pressure displacements were recorded during a set of ten shots per subject. The results revealed that expert biathletes seem to use a different strategy than expert rifle shooters, each of them adapting to the characteristics of their respective discipline. No significant pattern emerged from tests with novice rifle shooters, as their scores correlated only weakly with the various parameters measured in this study.

Adult↗
PubMed1988

[Analysis of advance visual indices in receiving a tennis serve].

The aim of this study is to analyse the differential visual patterns of expert and non-expert tennis players preparing to return a tennis serve. Two 16 mm films were used for testing purposes; 27 services were delivered and recorded on each film. The subjects had to identify verbally the type of serve delivered. During film viewing, eye movements were recorded by an Eye Mark Recorder NAC V. Results revealed that the expert players seem to use cues from the general position of the body during the ritual phase and cues from the racquet position during the execution phase.

Adult↗
PubMed1981

Influence of different types of physical fatigue on a visual detection task.

The present study was designed to investigate the effects of different types of physical fatigue-past demand for exertion-on the performance of a visual detection task performed with and without masking. 31 male subjects were first administered a VO2 max test and familiarized with the detection task. They were divided into two groups to control potential effects of masking. They were subjected to three experimental treatment involving the utilization of different sources of energy: (a) a short anaerobic alactic acid effort recruiting phosphocreatine, (b) a supramaximal effort (anaerobic lactic acid) recruiting glycogen without oxygen, and (c) a progressive (partially anaerobic) effort recruiting glycogen and oxygen. All three were performed on a treadmill. Blood samples were collected for the anaerobic lactacid and the partially anaerobic exercises. Once fatigued, all subjects undertook the detection task. A 2 X 3 X 2 X 8 analysis of variance, with repeated measures on the last three factors, was applied to the data (mask/no mask X type of exercise X pre-post performance measures X location of the letter to be detected). No significant difference was found for either the main effects or interactions, except for the location of the letter and the mask/no mask condition. It appears therefore that a physically fit population (mean VO2 max = 62.39 ml X kg(-1) X min(-1)) shows no detectable decrement in a perceptual task performed after fatiguing exercises recruiting various types of energy sources.

Adult↗
PubMed1981

The effects of physical or perceptual work loads on a coincidence/anticipation task.

This study was designed to analyze the effects of physical or perceptual work loads on a coincidence/anticipation task. Three experimental treatments were applied: (1) a physical work load, (2) a perceptual work load, and (3) a combination of the physical and the perceptual work loads. The dependent variable was performance on a coincidence/anticipation task, a throw at a moving target. Time errors and accuracy scores were recorded. The type of work load does not affect any of the dependent variables. However, all types of work load generated definite improvement pre- and posttest for the temporal constant error; better performance, as measured by constant error, was recorded for all subjects when the speed of the apparent movement being intercepted was 4.7 km/hr. Temporal variability was reduced in the subject performance at 8.1 km/hr.

Adult↗
PubMed1979

Influence of functional electrical stimulation training on premotor and motor reaction time.

This study was designed to investigate the influence of functional electrical stimulation on the improvement of reaction time and its fractionated components during learning an horizontal arm-sweep task. 62 subjects participated and were divided into control, stimulation, and trail/stimulation groups. Functional electrical stimulation was an effective method of improving total reaction time and its central component, premotor time.

Adult↗
PubMed1978

Influence of imposed metabolic fatigue on visual capacity components.

The present study was designed to investigate the effects of exercise to exhaustion on different components of visual capacity: visual field, and coincidence/anticipation capacity. 16 male subjects were first familiarized with the three visual tests, one day before being submitted to a prefatigue visual test. Metabolic fatigue was induced by working to exhaustion on a bicycle ergometer. Once fatigued, all subjects undertook the visual tests. Pre- and post-fatigue visual measurements were not significantly different. The results demonstrated the independence between metabolic fatigue and visual capacity.

Fatigue↗