Does general practitioner gatekeeping curb health care expenditure?
Gatekeeping systems appear to be better able to contain ambulatory care expenditure. More research is necessary to understand micro level mechanisms and to distinguish the effects of gatekeeping from other structural aspects of health care systems.
A temporal relationship was observed between the circadian rhythm of 6-sulfatoxymelatonin of the exclusively breast-fed babies and that of tryptophan in the mother's milk. Acting this amino acid as a zeitgeber entrainment of the biological rhythms in the breast-fed infant.