Kongenitale Strukturmyopathien

Congenital myopathies are a heterogeneous group of rare neuromuscular disorders, sometimes presenting as floppy infant syndrome but generally progressing slowly. They usually begin at birth or in childhood, rarely in adulthood. Congenital myopathies are classified according to their histological, immunohistological, and ultrastructural pattern and the underlying genetic defect. A growing number of causative genes have been identified in the last years. Several congenital myopathies reveal a remarkable phenotypic overlap. The most common congenital myopathies are the nemaline myopathies, core myopathies, centronuclear myopathies, and congenital fibre-type disproportion.     

Klinik und Genetik der Gliedergürteldystrophien

Limb girdle muscular dystrophies (LGMDs) are a clinically and genetically heterogeneous group of muscle disorders. Seven dominant (LGMD1A through G) and 15 recessive forms (LGMD2A through O) have been described. They often start in adolescence, and most patients end up wheelchair-bound 2–4 decades later. The syndrome begins in the pelvic girdle. Muscles of the shoulder girdle follow after a variable time interval. Allelic variants may present with a distal predilection of muscles, such as Miyoshi myopathy, which is caused by mutations in the dysferlin gene. The most frequent types of LGMD are calpainopathies (LGMD1A), mutations in the FKRP gene (LGMD2i), and dysferlinopathies (LGMD2B). Sarcoglycanopathies, which often start in childhood, are the next most frequent forms. In many LGMDs, a sarcolemmal protein is affected. Because of the huge heterogeneity, molecular genetic analysis normally follows a muscle biopsy and includes an extensive immunohistochemical workup. A specific therapy for this group of diseases is not yet available. Human genetic counseling is of primary importance. Treatment of contractures as well as special care for a developing cardiomyopathy are helpful for the patient.     

Enzymatic digestion of human plasma inter-alpha-trypsin inhibitor by snake venom metalloproteinases

Incubation of human plasma inter-alpha-trypsin inhibitor with crotalid, viperid, colubrid or elapid venoms resulted in random cleavage of the intact inhibitor (200,000 mol. wt) and formation of inhibitor of 130,000, 77,000, 58,000, and 38,000 mol. wt, along with several minor products. The overall patterns of digestion varied among the venoms studied. However, a 77,000 mol. wt inhibitor cleavage product was formed by all venoms tested, and this fragment was resistant to proteolysis even after a 24 hr incubation with the venoms. Venom pre-treated with phenylmethylsulfonyl fluoride digested inter-alpha-trypsin inhibitor; however, pre-treatment with EDTA completely stopped the reaction, indicating that venom metalloproteinases were responsible for the inhibitor digestion. The inhibitor cleavage products retained the ability to inhibit trypsin, but had no inhibitory activity against venom proteinases.     

Mutant carrying deletions in the two simian virus 40 early genes.

We isolated a simian virus 40 mutant, dl2194, which carried deletions in both early genes. One deletion removed 234 base pairs in the 54/59 region within the small-t-antigen coding sequence and the large-T-antigen gene intron. The second deletion removed 57 base pairs at the C terminus of the large-T-antigen coding sequence (0.20 map unit). dl2194 was a viable mutant, it carried a normal helper function for adenovirus growth on monkey cells, and it displayed the transformation properties of a small-t-antigen-negative single mutant. Therefore, none of the known large-T-antigen functions seemed to be altered by the C-terminal deletion.     

Human plasma alpha1-proteinase inhibitor: temporary inhibition and multiple molecular forms of the complex with porcine trypsin.

Human plasma α₁-proteinase inhibitor (M.W. 58,000) reacts with porcine trypsin to form a 1:1 complex (M.W. 76,000) which dissociates at pH 8.0 into a modified, inactive inhibitor (M.W. 54,000) and active trypsin. The % recovery of active trypsin decreases with increasing enzyme to inhibitor ratios. Unrecovered trypsin is present in modified, more stable, enzyme-inhibitor complexes.