Gastrointestinal melatonin: cellular identification and biological role.

Melatonin, a pineal hormone, because of its wide activity spectrum, is a subject of much current interest for biologists and physicians. It has been demonstrated that pineal gland is not an exclusive source of melatonin synthesis. Melatonin synthesis has been found in different sites of the organism, and a major source of extrapineal melatonin is the gastrointestinal tract. The role of melatonin in gastrointestinal functions is considered in the present review.

Geomagnetics and society interact in weekly and broader multiseptans underlying health and environmental integrity.

Evidence for the ubiquity and partial endogenicity of about-weekly (circaseptan) components and multiples and/or submultiples thereof (the multiseptans) accumulates as longer and denser records become available. Often attributed to a mere response to the social schedule, circaseptan components now have been documented to characterize environmental variables related to primarily non-photic solar effects. Plausibly, like circadians, circaseptans are anchored in genomes, from bacteria to humans, via both an internal and external evolution. If so, circaseptans, like circadians, may be found in the absence of a 7-day schedule, whereas the social schedule may play a synchronizing role and be responsible for the detection of prominent weekly variations in population statistics. The wobbliness of multiseptans and other components of some environmental time structures (chronomes) may correspond to the wobbliness of multiseptans found in cardiovascular morbidity statistics. Here, the latter stem primarily, but not exclusively, from an extensive database on the incidence of daily calls for an ambulance in Moscow, Russia from 1979-1981. A modulation of multiseptans and other chronome components of both environmental and biological variables by the about 11-year solar activity cycle (and of other low-frequency signals reviewed elsewhere) may account for prior controversies and scepticism about a variety of non-photic effects on biota. This is notably the case when relatively short series are analyzed without consideration of effects of unassessed long-term variations; this is the task of the new field of chronomics. In the spectral element of the chronomes of geophysical and biospherical variability, there are natural near weeks,apart from any precise 7-day periodicity.