Circadian clocks regulate the daily timing of many of our physiological, metabolic and biochemical functions. The immune system also displays circadian oscillations in immune cell count, synthesis and cytokine release, clock gene expression in cells and organs of the immune system as well as clock-controlled genes that regulate immune function. Circadian disruption leads to dysregulation of imm...

The circadian clock regulates a wide range of electrophysiological and developmental processes in plants. This paper presents, for the first time, the direct influence of a circadian clock on biologically closed electrochemical circuits in vivo. Here we show circadian variation of the plant responses to electrical stimulation. The biologically closed electrochemical circuits in the leaves of Al...

In golden-mantled ground squirrels, phase angles of entrainment of circadian locomotor activity to a fixed light-dark cycle differ markedly between subjective summer and winter. A change in ambient temperature affects entrainment only during subjective winter when it also produces pronounced effects on body temperature (Tb). It was previously proposed that variations in Tb are causally related ...

BACKGROUND Various clinical manifestations of cardiovascular diseases have a pattern of circadian variation. In this study, we investigated whether the onset and duration of paroxysmal supraventricular tachycardia (PSVT) has a circadian variation. METHODS AND RESULTS In our analysis, we included 105 patients with 498 PSVT episodes. In this study, the onset of PSVT did not have a uniform distr...

In 1729, Jean Jacques d’Ortous de Marian, a French scientist, made the fascinating observation that plants that unfolded their leaves when exposed to sunlight (presumably to increase photosynthesis, a process that had not yet been discovered) continued to rhythmically unfold their leaves in the morning and fold them in the evening even when they were maintained in constant darkness.1 d’Ortous h...

Guberan, E., Williams, M. K., Walford, Joan, and Smith, Margaret M. (1969). Brit. J. industr. Med., 26, 121-125. Circadian variation of F.E.V. in shift workers. The one-second forced expiratory volume (F.E.V.1.0), the forced vital capacity, and the oral temperature were measured in a group of men working a rotating three-shift system-2 to 10 p.m. one week, 10 p.m. to 6 a.m. the next week, and 6...

OBJECTIVES We sought to determine the circadian, weekly, and seasonal variation of coronary stent thrombosis. BACKGROUND Other adverse cardiovascular events such as acute myocardial infarction are known to have higher incidences during the early morning hours, Mondays, and winter months. METHODS The Mayo Clinic Percutaneous Coronary Intervention Registry was searched for patients admitted t...

OBJECTIVES We sought to investigate the impact of circadian patterns in the onset of acute myocardial infarction (AMI) on the practice of primary angioplasty. BACKGROUND A circadian variation in the time of onset of AMI with a peak in the morning hours has been described. METHODS We studied 1,702 consecutive patients with acute ST-segment elevation myocardial infarction treated with primary...

The role of the circadian clock in controlling the metabolism of entire trees has seldom been considered. We tested whether the clock influences nocturnal whole-tree water use. Whole-tree chambers allowed the control of environmental variables (temperature, relative humidity). Night-time stomatal conductance (gs ) and sap flow (Q) were monitored in 6- to 8-m-tall Eucalyptus globulus trees durin...

Delirium is associated with circadian rhythm disruption. In this study we have explored whether circadian variation of melatonin is an indicator for delirium. Melatonin levels were determined from the first day of hospitalization and up to three days after the onset of delirium. Patients who did not developed delirium exhibited a daily melatonin rhythm, while in patients that developed delirium...