MEDIAN NERVE INJURY AND THE TRANSVERSE WRIST CREASE INCISION IN OPEN CARPAL TUNNEL RELEASE

The author has recently had referred to him three patients with median nerve injuries who have had open carpal tunnel decompression via a small transverse wrist incision. Despite previous adverse reports, some surgeons persist with this technique.     

Progress in the autosomal segmental aneusomy syndromes (SASs): single or multi-locus disorders?

Based on cytogenetic observations, several syndromes have been previously identified as microdeletion-based disorders. In this review, recent progress is presented regarding whether one or multiple genes can be implicated in the pathogenesis of these segmentally aneusomic syndromes. The syndromes discussed include Angelman, Alagille, Williams, Langer-Giedeon, Prader-Willi, Smith-Magenis, Miller-Dieker, and DiGeorge/velocardiofacial or the 22q11 deletion syndromes. For Angelman and Alagille syndromes, single genes have been identified, whereas for Williams and Langer-Giedion syndromes, more than one gene can be implicated. Although there has been significant progress in dissecting the molecular basis for the other disorders, the ultimate answer regarding one versus several genes remains to be determined.      

Immunohistochemical localization of glutathione-S-transferase and glutathione peroxidase in adult Syrian hamster tissues and during kidney development.

Tissues from adult Syrian hamsters were studied with immunoperoxidase techniques using polyclonal antibodies to glutathione-S-transferase (rat liver and human placental enzymes) and human erythrocyte glutathione peroxidase. Most tissues immunostained similarly with these antibodies. Most notable was the cytoplasmic staining of mesenchyme tissues, especially smooth muscle, by all three antibodies. Epithelial cells stained distinctively, but usually less intensely than mesenchyme. Epithelial cells from all levels of the gastrointestinal tract, respiratory epithelium, transitional epithelium, and epidermis all showed strong staining with these antibodies. Other epithelial cell types were usually positive but showed less dramatic staining. Most epithelial tissues showed both nuclear and cytoplasmic staining; some also showed cell-surface (eg, cilia) staining. The role of these enzymes in cell differentiation of a stable organ was studied by immunostaining the kidney during its development. Early stroma (13- and 15-day fetuses) of the kidney (metanephric mesenchyme) showed strong cell-surface staining for glutathione transferases and moderate staining for glutathione peroxidase; renal tubules (which are epithelial cells) at this stage were negative for these markers. As renal tubules differentiated, first cytoplasm and then nuclei stained moderately, suggesting that glutathione-S-transferases and glutathione peroxidase are markers of both mesenchymal cells, including embryonic mesenchyme, and terminal differentiation of at least some epithelial cells.     

Differentiation of Brucella ovis from Brucella abortus by gas-liquid chromatographic analysis of cellular fatty acids

The cellular fatty acid composition of Brucella ovis and Brucella abortus strains was determined by gas-liquid chromatography. Both species were characterized by the presence of fatty acids 16:0, 17:0, 17:0 cyclopropane, 18:0, 18:1, and 19:0 cyclopropane; B. ovis also contained some 15:0. There were differences in the relative proportions of the fatty acids present, and it was possible to differentiate B. ovis from B. abortus on the basis of the absence of 15:0, lower concentrations of 17:0 and 18:1, and higher concentrations of 19:0 cyclopropane in B. abortus. The data indicate that analysis of cellular fatty acid composition by gas-liquid chromatography can be used for the identification of B. ovis and its differentiation from B. abortus.     

Missense mutation in a von Willebrand factor type A domain of the alpha 3(VI) collagen gene (COL6A3) in a family with Bethlem myopathy

The Bethlem myopathy is a rare autosomal dominant proximal myopathy characterized by early childhood onset and joint contractures. Evidence for linkage and genetic heterogeneity has been established, with the majority of families linked to 21q22.3 and one large family linked to 2q37, implicating the three type VI collagen subunit genes, COL6A1 (chromosome 21), COL6A2 (chromosome 21) and COL6A3 (chromosome 2) as candidate genes. Mutations of the invariant glycine residues in the triple-helical domain-coding region of COL6A1 and COL6A2 have been reported previously in the chromosome 21-linked families. We report here the identification of a G-->A mutation in the N-terminal globular domain-coding region of COL6A3 in a large American pedigree (19 affected, 12 unaffected), leading to the substitution of glycine by glutamic acid in the N2 motif, which is homologous to the type A domains of the von Willebrand factor. This mutation segregated to all affected family members, to no unaffected family members, and was not identified in 338 unrelated Caucasian control chromosomes. Thus mutations in either the triple-helical domain or the globular domain of type VI collagen appear to cause Bethlem myopathy.      

doublecortin is the major gene causing X-linked subcortical laminar heterotopia (SCLH)

Subcortical laminar heterotopia (SCLH), or 'double cortex', is a cortical dysgenesis disorder associated with a defect in neuronal migration. Clinical manifestations are epilepsy and mental retardation. This disorder, which mainly affects females, can be inherited in a single pedigree with lissencephaly, a more severe disease which affects the male individuals. This clinical entity has been described as X- SCLH/LIS syndrome. Recently we have demonstrated that the doublecortin gene, which is localized on the X chromosome, is implicated in this disorder. We have now performed a systematic mutation analysis of doublecortin in 11 unrelated females with SCLH (one familial and 10 sporadic cases) and have identified mutations in 10/11 cases. The sequence differences include nonsense, splice site and missense mutations and these were found throughout the gene. These results provide strong evidence that loss of function of doublecortin is the major cause of SCLH. The absence of phenotype-genotype correlations suggests that X-inactivation patterns of neuronal precursor cells are likely to contribute to the variable clinical severity of this disorder in females.