Hereditary demyelinating peripheral neuropathies consist of a heterogeneous group of genetic disorders that includes hereditary neuropathy with liability to pressure palsies (HNPP), Charcot-Marie-Tooth disease (CMT), Dejerine-Sottas syndrome (DSS), and congenital hypomyelination (CH). The clinical classification of these neuropathies into discrete categories can sometimes be difficult because there can be both clinical and pathologic variation and overlap between these disorders. We have identified five novel mutations in the myelin protein zero (MPZ) gene, encoding the major structural protein (P0) of peripheral nerve myelin, in patients with either CMT1B, DSS, or CH. This finding suggests that these disorders may not be distinct pathophysiologic entities, but rather represent a spectrum of related "myelinopathies" due to an underlying defect in myelination. Furthermore, we hypothesize the differences in clinical severity seen with mutations in MPZ are related to the type of mutation and its subsequent effect on protein function (i.e., loss of function versus dominant negative).
One biceps muscle of 8 patients with Duchenne muscular dystrophy was injected at 55 sites with a total of 55 million viable, purified, and contamination-free normal myoblasts (myoblast transfer). The other biceps of each patient was injected with a placebo to serve as a control. The procedure was blinded to the patients, parents, and investigators. Myoblasts derived from a biopsy specimen of the fathers were cultured and purified under strict conditions and carefully screened for microbial contamination. All patients received cyclophosphamide for immunosuppression for 6 or 12 months. No serious complications were observed after myoblast transfer, indicating that the procedure is safe. The overall therapeutic efficiency of myoblast transfer was poor as judged by the results in maximal voluntary force generation, dystrophin content of the muscle, magnetic resonance imaging of the muscle, and the lack of donor-derived DNA and dystrophin messenger RNA in the injected muscle. An improved efficiency of the take of myoblasts might be achieved by using younger cells and injecting the myoblasts with a myonecrotic agent (to increase the prevalence of regeneration) and a basal laminal fenestrating agent.
The effects of the variables of hemispheric side of lesion, age at injury and severity of cerebral damage on language performance and hand dominance were investigated in groups of hemiparetic children. Severity of cerebral damage was defined by the degree of structural abnormality shown on computed tomography (CT) scans. Tests of auditory verbal comprehension and object naming were used as indicators of productive and receptive language skills. The responses to a series of questions on a handedness inventory provided a rated measure of hand dominance. The results indicated that language deficits characterize the performance of all patient groups with left cerebral injuries. Impairments are more profound, however, in the case of left hemisphere injuries acquired after the age of 5 years. In addition, prenatal and early postnatal left cerebral lesions consistently result in strong sinistrality. It is concluded that the crucial variable underlying the demonstration of language deficits and left hand dominance is not severity of lesion but age at injury and hemispheric side of lesion.
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