concanavalin-a and Muscular-Atrophy

Changes in the cytoplasm of skeletal muscle fibres during necrosis, regeneration, and neurogenic atrophy have been studied in a wide range of human neuromuscular diseases with a panel of eleven biotinylated lectins and by immunohistochemical staining for the cytoskeletal protein desmin. Increased binding of several lectins was observed in both necrotic and regenerating fibres, with Concanavalin A the most consistently positive lectin. Staining for desmin was strong in the cytoplasm of regenerating and partially damaged fibres and was lost in necrotic fibres, although there were differences in the staining reactions of the two antidesmin antibodies used. In fibres which had undergone neurogenic atrophy, cytoplasmic lectin binding was seen only with Griffonia simplicifolia 1 lectin, and desmin was expressed more strongly than in normal fibres. Lectin binding and immunohistochemical staining from desmin can supplement the information obtained from muscle biopsies by conventional histochemical methods and lead to a better understanding of the mechanisms of muscle damage.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Child; Child, Preschool; Concanavalin A; Cytoplasm; Desmin; Humans; Infant; Lectins; Middle Aged; Muscles; Muscular Atrophy; Necrosis; Protein Binding; Regeneration

Atrophy in a denervated muscle results from the disuse caused by paralysis of the muscle, and from the loss of special nerve-derived trophic substances. Crude preparations of protein from rat or sheep sciatic nerves have been shown to prevent the nondisuse atrophy of the rat's extensor digitorum longus muscle when injected into the denervated muscle daily for 1 week. Aqueous extracts of sheep sciatic nerves were fractionated by gel-liquid chromatography. After each step of purification, the trophic activities of the various fractions were assayed in the rat. Cross-sectional areas of type IIB muscle fibers in the denervated extensor digitorum longus were measured to determine which injected fraction contained the active principle. Affinity chromatography on concanavalin A-agarose revealed that the trophic substance was a glycoprotein. Further fractionation by gel filtration indicated that the active substance had a molecular weight in the range of 90,000 to 130,000. Ion-exchange chromatography on DEAE-cellulose yielded an active fraction containing substances with isoelectric points between 7.0 and 7.2, determined by polyacrylamide gel isoelectric focusing. This active fraction was resolved into 15 bands on sodium dodecyl sulfate-gel electrophoresis. Two bands had apparent molecular weights of 91,300 and 127,400. The active factor was shown thus to be a glycoprotein, molecular weight approximately 100,000, isoelectric point approximately 7.0. It may be one of two protein bands that are similar to it in molecular weight.

Topics: Animals; Chromatography, Affinity; Chromatography, Gel; Chromatography, Ion Exchange; Concanavalin A; Female; Filtration; Muscle Denervation; Muscular Atrophy; Nerve Growth Factors; Nerve Tissue Proteins; Sciatic Nerve; Sheep