Mast cell in leprosy.

Mast cell distribution in the affected skin and in the apparently normal skin at least 10 cm away from the lesion was studied in 250 leprosy patients. These cells were found and were more numerous in the apparently normal skin of established cases of leprosy as well amongst indeterminate group. Absence of mast cells was conspicuous in 16.7% LL, 41.7% BB, 40.9% BT, and 68.0% TT lesions. It is suggested that mast cells might play a role in the early stages of the disease and in postreactional connective tissue proliferation.

Effect of melatonin on glucose tolerance and blood glucose circadian rhythm in rabbits.

Experimental studies on pinealectomized animals and in vitro studies using pancreatic tissue, have indicated that the pineal gland has a suppressive effect on the pancreatic B cells which secrete insulin. In this study, melatonin, was injected into rabbits and a statistically significant decrease in glucose tolerance was noted. The effect of melatonin in influencing the circadian rhythm of blood glucose was also studied in rabbits. Results showed that melatonin influences the circadian rhythm leading to a shift in the occurrence of minimum levels from 16.00 hr to 04.00 hr (next day) during fasting and from 16.00 hr to 20.00 hr during feeding. Also melatonin treatment lead to a statistically significant rise in blood glucose levels. It is probable that melatonin administration reduces glucose tolerance and influences the blood glucose circadian rhythm mainly through its effects on insulin release by pancreatic B cells.