Circadian rhythms are biological processes displaying endogenous and entrainable oscillations of about 24 h. In mammals the sleep/wake cycle, core body temperature fluctuation, and diurnal variation of blood pressure and heart rate are among the most well-known circadian rhythms. These rhythms are not just the consequence of activity/rest cycles, but are also controlled by molecular clocks, a b...

A rapid microspectrophotometric method was used to measure zinc concentrations in plasma and erythrocytes. A circadian variation in plasma zinc related to the ingestion of food was observed. Fasting plasma zinc concentrations were low in 20 out of 23 paraplegic patients with pressure sores, indicating that oral zinc supplementation may be expected to accelerate healing in such patients. Erythro...

BACKGROUND Different studies have shown circadian variation of ischemic burden among patients with ST-Elevation Myocardial Infarction (STEMI), but with controversial results. The aim of this study was to analyze circadian variation of myocardial infarction size and in-hospital mortality in a large multicenter registry. METHODS This retrospective, registry-based study was based on data from AM...

In response to exogenous rhythms of light and temperature, most organisms exhibit endogenous circadian rhythms (i.e. cycles of behavior and gene expression with a periodicity of approximately 24 h). One of the defining characteristics of the circadian clock is its ability to synchronize (entrain) to an environmental rhythm. Entrainment is arguably the most salient feature of the clock in evolut...

Dijk, Derk-Jan, and Steven W. Lockley. Invited Review: Integration of human sleep-wake regulation and circadian rhythmicity. J Appl Physiol 92: 852–862, 2002; 10.1152/japplphysiol.00924.2001.—The human sleep-wake cycle is generated by a circadian process, originating from the suprachiasmatic nuclei, in interaction with a separate oscillatory process: the sleep homeostat. The sleep-wake cycle is...

Viable circadian clocks help organisms to synchronize their development with daily and seasonal changes, thereby providing both evolutionary fitness and advantage from an agricultural perspective. A high-resolution mapping approach combined with mutant analysis revealed a cereal ortholog of Arabidopsis thaliana LUX ARRHYTHMO/PHYTOCLOCK 1 (LUX/PCL1) as a promising candidate for the earliness per...

Plasma levels of fibrinopeptide A (FPA), beta-thromboglobulin (BTG), and platelet factor 4 (PF4) were examined on venous plasma samples taken every 4 hours for 24 hours in 20 patients with variant angina and 20 patients with stable exertional angina together with 24-hour Holter recordings. The mean plasma FPA levels (ng/ml) at 2:00 PM, 6:00 PM, 10:00 PM, 2:00 AM, 6:00 AM, and 10:00 AM were 4.6 ...

Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (Q...