Biomedical subjects

P Boissy

Publications and source records attributed to P Boissy.

4 recordsLinked to original sources

PubMed1999

Maximal grip force in chronic stroke subjects and its relationship to global upper extremity function.

OBJECTIVES: Previous studies have shown that recovery of recordable grip strength in acute stroke subjects is one of the most sensitive assessments of initial upper limb recovery and a good prognostic factor for latter recovery. The objectives of this study were to test the reliability of maximal voluntary grip force (MVGF) measures and evaluate the relationship between paretic grip strength deficit and paretic upper extremity function in chronic stroke subjects. DESIGN: Over a three-week period, bilateral MVGF was assessed three times with a modified strain gauge dynamometer in 15 chronic stroke subjects and 10 control subjects. The paretic MVGF deficit was expressed in relation to the MVGF of the nonaffected hand. OUTCOME MEASURES: Upper extremity function in stroke subjects was measured using the Fugl-Meyer, the upper extremity performance test for the elderly (TEMPA), Box and Block and finger-to-nose tests. RESULTS: MVGF measures in both groups of subjects demonstrated good reliability (intraclass correlation, ICC >0.86) and low standard error measurements (SEM). The paretic MVGF of the stroke subjects was greatly impaired in comparison to the control subjects. Results of linear and quadratic regressions analyses show that this impairment was significantly correlated (p <0.01) with the performance of the stroke subjects on the four upper extremity function tests. The percentages of variances explained by the MVGF deficit on all four upper extremity tests varied from 62% to 78% for the linear regressions and from 72% to 93% for the quadratic regressions. CONCLUSIONS: These results suggest that the paretic maximal grip strength, normalized with the maximal grip strength on the nonaffected side, appears to be a valuable outcome measure of upper extremity function in chronic stroke subjects.

Adult↗

PubMed1998

A static dynamometer measuring simultaneous torques exerted at the upper limb.

The majority of available dynamometers are designed to measure force or torque in one specific direction, one joint at a time. For the quantification of motor incoordination in neurological patient populations, these dynamometers provide limited information about the global behavior of the limb under investigation. This report describes the potential use and function of a static dynamometer measuring torques exerted simultaneously at the shoulder (flexion-extension, abduction-adduction, internal-external rotation), elbow (flexion-extension), and forearm (pronation-supination). Orthogonal forces were measured at the arm and wrist using strain gauge transducers interfaced with a laboratory computer. The lever arms were specified to a software program and the joint torques were calculated in real time according to static equilibrium equations. The use of the dynamometer is illustrated by characterizing for one hemiparetic subject, the joints torques recorded at the shoulder, elbow, and forearm during isolated submaximal grip exertions at different force levels on both sides. The torques generated at the shoulder, elbow and forearm during the hand grip tasks on the affected side were significantly higher than those obtained on the nonaffected side and increased with the grip force level. These differences probably reflect the loss of movement selectivity observed following a lesion in the central nervous system. Further studies are currently being undertaken in neurological patient populations to characterize and quantify motor deficits using this dynamometer. As a long term goal, we hope that the method and technologies described here will contribute to the evaluation and rehabilitation of these populations.

Biofeedback, Psychology↗

PubMed1998

Aggregation of mononucleated precursors triggers cell surface expression of alphavbeta3 integrin, essential to formation of osteoclast-like multinucleated cells.

Alphavbeta3 is a key integrin mediating adhesion of multinucleated osteoclasts during bone resorption. 1, 25-dihydroxyvitamin D3 upregulates alphavbeta3 integrin expression in mononucleated osteoclast precursors and concomitantly stimulates their differentiation into osteoclasts. This suggests that this integrin could play a major role during osteoclast differentiation. We have developed an in vitro model, in which 1, 25-dihydroxyvitamin D3 sequentially modifies the behavior of macrophages: It first induces rounding up of these cells, then their subsequent aggregation and spreading, which finally leads to cell fusion and the formation of osteoclast-like multinucleated giant cells. We show that, while 1,25-dihydroxyvitamin D3 stimulates the de novo synthesis of alphavbeta3 in macrophages early in this process, its accumulation on the surface is triggered by cell aggregation. A high level of integrin alphavbeta3 cell surface expression correlates with macrophage spreading preceding fusion. This was confirmed by means of novel cell permeable peptides containing the C-terminal sequence of the integrin beta3 tail to specifically block (alphavbeta3 function. Although this peptide has no effect on the aggregation step, it disrupts the spreading of osteoclast precursors and consequently inhibits their fusion. These findings suggest a novel role of the integrin alphavbeta3 in a discrete step of osteoclast differentiation.

Amino Acid Sequence↗

PubMed1997

Characterization of global synkineses during hand grip in hemiparetic patients.

OBJECTIVE: Global synkineses are defined as nonpurposive associated movements on the involved side of hemiparetic subjects that are triggered during a voluntary movement. The purpose of this study was to characterize the intensity and pattern of upper limb global synkineses in hemiparetic subjects with a static biarticular dynamometer and electromyography during maximal progressive hand grip on the unaffected side. DESIGN: Survey, convenience sample. SETTINGS: University secondary care rehabilitation center. DATA SET: Global synkineses (ie, torques and electromyographic activities) in patients with severe (n = 8) and moderate (n = 7) deficits in motor performance, as evaluated by the Fugl-Meyer assessment, were compared with those obtained in a group of healthy subjects (n = 11). Clinically the subjects from the severe deficit group were more spastic and showed less strength at the elbow than the subjects from the moderate deficit group. RESULTS: Results of analyses of variance showed significant increases of shoulder torque in flexion and internal rotation, and elbow torque in flexion, with increasing force exertion during contralateral hand grip in subjects with severe deficits (p < .05). Furthermore, in these subjects increases of electromyographic activity were also observed in biceps brachii, brachioradialis, and triceps brachii muscles with increasing hand grip force levels. In contrast, no significant torques or electromyographic increases were observed in subjects with moderate deficits and in control subjects during contralateral hand grip exertions. CONCLUSION: These results provide a quantitative assessment of the kinematic and electromyographic patterns of global synkineses and their correlates with clinical observations. Within the limits of the experimental results presented in this study, it is suggested that global synkineses result from contralateral overflow of the voluntary command to hyperexcitable motoneuron pools.

Adult↗