Biomedical subjects

Joan Ohayon

Publications and source records attributed to Joan Ohayon.

4 recordsLinked to original sources

PubMed2005

Interferon-beta1a therapy in human T-lymphotropic virus type I-associated neurologic disease.

Human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is an immune-mediated inflammatory disorder of the central nervous system. Immune activation in the host, which results from high levels of persistent antigenic stimulation and from transactivation of host immunoregulatory genes by HTLV-I, appears important in the pathogenesis of HAM/TSP. In a single-center, open-label trial, 12 patients with HAM/TSP were treated with doses of interferon-beta1a of up to 60mug twice weekly, based on its antiviral and immunomodulatory effects. Primary end points were immunological and virological measures that are potential biomarkers for HAM/TSP. Interferon-beta1a therapy reduced the HTLV-I tax messenger RNA load and the frequency of potentially pathogenic HTLV-I-specific CD8(+) cells. The HTLV-I proviral DNA load remained unchanged. Spontaneous lymphoproliferation, a marker of T-cell activation in HAM/TSP, also was reduced. Some measures of motor function were improved, and no significant clinical progression occurred during therapy. These results indicate that interferon-beta1a may beneficially affect the immune mechanisms central to the pathogenesis of HAM/TSP.

Adult↗

PubMed2004

Training-dependent plasticity in patients with multiple sclerosis.

Cortical reorganization has been demonstrated in the motor network that mediates performance of a motor task in patients with multiple sclerosis. How this network responds to motor training is not known. This study examined functional MRI (fMRI) activation patterns associated with performance of a motor task, consisting of repetition of directionally specific voluntary thumb movements, before and after motor training in a group of multiple sclerosis patients with mild motor impairment of the right upper extremity. Patients and healthy subjects were scanned in one session before, during and after a 30 min training period. fMRI data obtained during rest, thumb flexion (trained movement) and thumb extension (untrained movement) were analysed using random effects analysis (SPM99). Motor kinematics of training motions and EMG from the resting hand were monitored with an accelerometer and surface EMG electrodes. Kinematics of thumb movements before, during and after training were comparable in the absence of mirror EMG activity in the resting hand. Before training, thumb movements elicited more prominent activation of the contralateral dorsal premotor cortex [PMd, Brodmann area (BA) 6] in multiple sclerosis patients than in controls. After training, unlike the control group, multiple sclerosis patients did not exhibit task-specific reductions in activation in the contralateral primary somatosensory (S1), motor (M1) and adjacent parietal association (BA 40) cortices. These results indicate that patients engage the contralateral PMd more than controls in order to perform directionally specific movements before training. The absence of training-dependent reductions in activation in S1, M1 and BA 40 is consistent with a decreased capacity to optimize recruitment of the motor network with practice.

Adult↗

PubMed2004

Humanized anti-CD25 (daclizumab) inhibits disease activity in multiple sclerosis patients failing to respond to interferon beta.

Identifying effective treatment combinations for MS patients failing standard therapy is an important goal. We report the results of a phase II open label baseline-to-treatment trial of a humanized monoclonal antibody against CD25 (daclizumab) in 10 multiple sclerosis patients with incomplete response to IFN-beta therapy and high brain inflammatory and clinical disease activity. Daclizumab was very well tolerated and led to a 78% reduction in new contrast-enhancing lesions and to a significant improvement in several clinical outcome measures.

Adult↗

PubMed2004

Kinematic specificity of cortical reorganization associated with motor training.

Motor training consisting of repetition of directionally specific voluntary thumb movements elicits a short-term memory trace that encodes the kinematic details of the practiced motions in the primary motor cortex. Here, we studied activation patterns associated with this form of training using functional magnetic resonance imaging under careful monitoring of motor training kinematics and electromyography. We identified task-specific reductions in activation in contralateral motor cortex, a region that controls executive motor output, as well as somatosensory cortex and inferior parietal lobule, regions in charge of monitoring motor training kinematics. Our findings are consistent with the hypothesis that a short training period consisting of repetition of finger motions leads to cortical reorganization characterized by a smaller and more efficient network that is specific for the trained movement direction.

Adult↗