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Biomedical subjects

S H Appel

Publications and source records attributed to S H Appel.

At least 217 records · Page 12Linked to original sources
PubMed1974

Serum globulin in myasthenia gravis: inhibition of alpha-bungarotoxin binding to acetylcholine receptors.

Serum factors that inhibit the binding of (125)I-labeled alpha-bungarotoxin to the acetylcholine receptor extracted in detergent from denervated rat muscle were detected by a sensitive assay. The serum of at least 5 and possibly 11 out of 15 patients with myasthenia gravis showed inhibitory activity that was localized to the globulin fraction. No controls showed inhibitory activity. The demonstration of inhibitory globulins may help explain the involvement of the immune system in the pathophysiology of the neuromuscular junction in patients with myasthenia gravis.

Acetylcholine↗
PubMed1974

Electron spin resonance studies of erythrocytes from patients with myotonic muscular dystrophy.

Electron magnetic resonance experiments have demonstrated that spin-labeled myotonic erythrocyte membranes have spectra that are recognizably different from those of normal erythrocytes. The spin label incorporated in the erythrocyte membranes of patients having myotonic muscular dystrophy is apparently located in a less polar and somewhat more fluid region than the label in a normal membrane. Although the mechanisms of molecular interaction and their relationship to enzymatic differences is unclear, the results lend confirmation to the suggestion that myotonic muscular dystrophy may be a disease resulting from a basic membrane abnormality.

Cell Membrane↗
PubMed1973

Phosphorylation of muscle membranes: identification of a membrane-bound protein kinase.

A membrane-bound protein kinase occurs in membranes derived from rat skeletal muscle and appears limited to a surface membrane fraction. The enzyme is magnesium dependent, is only minimally stimulated by cyclic nucleotides, and phosphorylates serine and to a lesser extent threonine residues of three membrane proteins with molecular weights of less than 30,000.

Adenosine Triphosphate↗
PubMed1973

Protein kinase activity in erythrocyte ghosts of patients with myotonic muscular dystrophy.

Myotonic muscular dystrophy is a disorder of humans that involves many organ systems. Physiological studies have suggested that the fundamental defect is of membrane origin. Heretofore, no reproducible metabolic abnormalities have been demonstrated. In the present studies we used erythrocyte ghosts as a convenient source of purified membranes that do not possess changes of denervation, dystrophy, and fibrosis that might complicate the interpretation of muscle membrane changes. Our experiments demonstrated a significant difference in the phosphorylation of erythrocyte ghost protein by [gamma-(32)P]ATP, with endogenous protein kinase of erythrocyte membrane as the enzyme source. After ghosts were kept for 1 week at -20 degrees , phosphorylation of membrane protein in eight controls was twice as high as endogenous protein kinase activity measured in fresh preparations. No stimulation was seen in preparations from seven myotonic dystrophy patients from three different families. This reproducible difference in normal and myotonic membranes may represent an important new approach to studies of this debilitating inborn error of metabolism.

Adenosine Triphosphate↗