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PubMed1968

Mitosis and intermediate-sized filaments in developing skeletal muscle.

A new class of filaments intermediate in diameter between actin and myosin filaments has been demonstrated in skeletal muscle cells cultured from chick embryos. These filaments, which account for the majority of free filaments, average 100 A in diameter. They may run for more than 2 micro in a single section and can be distinguished in size and appearance from the thick and thin filaments assembled into myofibrils. The 100-A filaments are seen scattered throughout the sarcoplasm at all stages of development and show no obvious association with the myofibrils. The 100-A filaments are particularly conspicuous in myotubes fragmented by the mitotic inhibitors, colchicine and Colcemid. In addition, filaments similar in size and appearance to those found in myotubes are present in fibroblasts, chondrocytes, and proliferating mononucleated myoblasts. The 100-A filaments are present in cells arrested in metaphase by mitotic inhibitors. Definitive thick (about 150 A) or thin (about 60 A) myofilaments are not found in skeletal myogenic cells arrested in metaphase. Myogenic cells arrested in metaphase do not bind fluorescein-labeled antibody directed against myosin or actin. For these reasons, it is concluded that not all "thin" filaments in myogenic cells are uniquely associated with myogenesis.

Animals↗

PubMedDate not supplied

[Late sequelae of severe injuries to the viscerocranium: clinical, radiographic and CT findings].

After 1 to 7 years the late results of the surgical treatment of 21 patients with partly severe viscerocranial fractures have been evaluated by means of clinical as well as radiographic and CT examinations (with special thin sections and reconstructions). In demonstrating fractures and hemorrhages or mucosal swelling in the sinuses CT was found to be superior--except for fractures of the floor of the orbita and the nasal bone. Clinical dysfunctions and disorders included among others impaired eye motility (5), optic nerve lesions (2), bone prominences (14; predominantly at the orbital margins, in one case resulting in severe deformity of the face), dental and functional masticatory disorders (10), sinus problems and headache (11). The number of fractures that could be demonstrated by radiography and CT was reduced from 336 to 186, and that of fragment dislocations even to less than a quarter of the original figure. Apart from mucosal swelling and 2 hemorrhages, the sinuses--although in some cases severely injured--were well pneumatized again.

Adolescent↗