This model predicted the probability of successful guidewire crossing within 30 min very well and can be applied for difficulty grading.

Serum melatonin concentrations were determined by RIA in 81 healthy humans, aged 1-92 yr. The daytime (0900-1100 h) serum levels of melatonin decreased progressively with advancing age. No sex difference was noted. The nocturnal rise of serum melatonin in the aged group was significantly reduced compared with that in the young group. These results suggest that serum melatonin may be secreted under the agerelated neural control of pineal metabolism. (J Clin Endocrinol Metab 55: 27, 1982) T HE PHYSIOLOGICAL role of melatonin in man has not been defined. However, the characteristic circadian periodicity of serum melatonin, with a prominent peak during the night, has been found in humans (1-4). Additional factors other than the light-dark cycle, such as the sleep-wake cycle (1, 3, 5), the menstruation cycle (6), and season of the year (7), have been shown to modulate serum melatonin levels in man. Whether serum melatonin levels vary with aging was determined during our studies to estimate the serum melatonin levels in relation to age and sex and to examine its diurnal variations in young and aged persons. Materials and MethodsEighty-one human subjects (44 men and 37 women), aged 1-92 yr, were studied for the determination of the daytime concentration of melatonin. Five young men (mean ± SEM, 26.4 ± 2.3 yr; young group) and 5 aged men (84.8 ± 1.8 yr; aged group) were studied for the examination of the diurnal variations.

Most CTO lesions can be safely and successfully treated with PCI utilizing contemporary advanced techniques. Invasiveness and potential risks of these strategies, which have been the greatest concerns of CTO treatment, may be acceptable in the majority of cases considering the actual incidences of related adverse events and the procedural success rates.

No abstract