This year's surgeon general's report on smoking and health is the first such report to focus on young people. From extensive data that indicate that tobacco use is a pediatric epidemic, the report reached six major conclusions: (1) Nearly all first use of tobacco occurs by age 18. (2) Most adolescent smokers are addicted to nicotine. (3) Tobacco is often the first drug used by young people who subsequently use illegal drugs. (4) There are identified psychosocial risk factors for the onset of tobacco use. (5) Cigarette advertising also appears to increase young people's risk of smoking. (6) Communitywide efforts have successfully reduced adolescent use of tobacco. This commentary restates each of the six conclusions, summarizes the data that support each, and then considers the implications of the conclusions for public health action.

Testicular Leydig cell hyperplasia was observed in two brothers presenting with progressive sexual precocity at 2 yr of age. Virilization was shown to result from increased secretion rather than decreased clearance of gonadal testosterone. Testosterone hypersecretion appeared to be gonadotropin independent, as basal and gonadotropin-releasing hormone-induced serum LH concentrations were low by both RIA and bioassay. Adrenal steroidogenesis was demonstrated to be normal by ACTH stimulation, dexamethasone suppression, and split adrenal venous function tests. Testicular histology revealed immature reproductive structures in the 2 yr old, but advanced spermatogenesis in the 3 yr-old brother. The etiology of both Leydig cell hyperplasia and reproductive testicular maturation in the absence of significant gonadotropin secretion remains to be established.

Cultured lymphocytes transformed by Epstein-Barr virus were employed to study insulin receptors from a patient with extreme insulin resistance associated with the syndrome ofleprechaunism. With cultured lymphocytes from normal subjects, insulin binding to its receptor is exquisitely sensitive to changes in temperature and pH. In cells from normal subjects, insulin binding was increased by approximately 250% as the temperature was decreased from 37C to 12C. In contrast, with cells from the leprechaun, insulin binding was only approximately 30% higher at 12"C than at 37C. Similarly, insulin binding to cells from the leprechaun was markedly less sensitive to changes in pH, as compared to cells from normal subjects. Binding studies suggested that the number ofinsulin receptors per cell was within the normal range in this patient. Despite the unusual characteristics ofinsulin binding in cells from this insulin-resistant patient, the receptors were typical in at least two respects: (i) binding was inhibited normally by antibodies to the receptor; and (ii) the specificity for insulin analogs was normal (chicken insulin > porcine insulin >> guinea pig insulin > porcine proinsulin). This patient has an inborn error affecting insulin receptor function. The receptor's binding function was abnormal in having decreased sensitivity to alterations in temperature and pH. However, the level of insulin binding to cells from the leprechaun was within normal limits. Consequently, the hormonal resistance probably results from a decreased ability of the receptor to couple insulin binding to insulin action.

No abstract