Muscle carnitine deficiency presenting as familial fatal cardiomyopathy

Three siblings presented with fatal cardiomyopathy confirmed by electron microscopy, and normal serum but low muscle carnitine concentrations. A fourth had similar signs but remained asymptomatic. He was treated with carnitine orally which increased the concentration in muscle, though it remained below normal. Electron microscopic features were unchanged.

Effect of theophylline on the proportion and function of T-suppressor cells in asthmatic children

T-cell subpopulations and their function were studied in asthmatic children with or without theophylline therapy. A decreased proportion and function of theophylline-sensitive T-suppressor cells was found in fresh peripheral blood of asthmatic children. Following peripheral blood mononuclear cells (PBMC) incubation in theophylline-free medium, the proportion of theophylline-sensitive T-cells in asthmatic children treated with theophylline was elevated to normal values. However, their suppressive effect on control lymphocyte proliferation was unchanged.

Leucine-induced hypoglycemia in a family: effect of diphenylhydantoin, oxprenolol, and diazoxide

The present report describes a mother and 2 children with leucine-induced hypoglycemia (LIH). Hypoglycemic episodes following high-protein meals first appeared at age 4-7 months. Leucine-stimulation tests triggered marked hyperinsulinism and hypoglycemia in the children and a milder but abnormal response in the mother. To evaluate the therapeutic effects and to study the mechanism of hyperinsulinism in LIH, the leucine test was repeated under treatment with diphenylhydantoin, oxprenolol (a beta-blocker), and diazoxide. Diazoxide abolished hyperinsulinism; diphenylhydantoin did not affect the response to leucine; and oxprenolol, tested in the mother only, increased hyperinsulinism and hypoglycemia. Our results indicate that LIH is an autosomal dominant disorder; LIH may persist into adulthood with milder clinical symptoms and chemical response to leucine; diazoxide is the treatment of choice in LIH. Considering the effects of the three agents on stimulated release of insulin, it is concluded that leucine triggers hyperinsulinism by a mechanism different from that of glucose and beta-adrenergic receptors.

Effects of theophylline on urinary excretion of cyclic AMP, calcium, and phosphorus in normal subjects

The present study was designed to examine the effects of acute theophylline administration on urinary excretion of cyclic adenosine monophosphate (cAMP), calcium, and phosphorus in normal subjects. The results demonstrated that at therapeutic doses (5 mg i.v./kg body weight) theophylline exerted a distinct biologic effect on renal tubular activity in 5 normal subjects: an increase in nephrogenous cAMP accompanied by a rise in phosphate and calcium urinary excretion. Beyond the clinical implications, the data suggest that theophylline, in contrast to parathyroid hormone, may be acting via cAMP to exert both its phosphaturic and calciuric effect on renal tubules.