Experimental and clinical studies indicate that clinical depression may be associated with disturbances of circadian rhythms. To explore the interaction between circadian rhythmicity, behavioral state, and monoaminergic systems, the present study investigated the effects of chronic administration and withdrawal of the following antidepressant agents on circadian wheel-running rhythms of laborat...

Patients with human immunodeficiency virus (HIV) infection exhibit changes in sleep patterns, motor disorders, and cognitive dysfunction; these symptoms may be secondary to circadian rhythm abnormalities. Studies in mice have shown that intracerebral injection of an HIV protein, transactivator of transcription (Tat), alters the timing of circadian rhythms in a manner similar to light. Therefore...

The initial stages of diapause induction - as summer gives way to autumn involve a process time measurement in which the duration daylength (or nightlength) is determined by photoperiodic 'clock' based upon circadian system. In many insects so far examined, photophase sufficient and illuminance resets oscillator constant phase equivalent beginning 'subjective night' (Circadian time, CT 12 h) wh...

Nearly all living organisms, including some bacterial species, exhibit biological processes with a period of about 24 h called circadian (from the Latin circa, about, dies, day) rhythms. These rhythms allow living organisms to anticipate the daily alternation of light and darkness. Experiments carried out in cyanobacteria have shown the adaptive value of circadian clocks. In these experiments a...

Circadian clocks coordinate physiological, behavioral, and biochemical events with predictable daily environmental changes by a self-sustained transcriptional feedback loop. CLOCK and ARNTL are transcriptional activators that regulate Per and Cry gene expression. PER and CRY inhibit their own transcription, and their turnover allows this cycle to restart. The transcription factors BHLHB2 and BH...

[no abstract available]

conclusions the current study revealed that the iranian nurses are exposed to a considerable risk of personal accomplishment. also, job burnout is in association with shift working and low job satisfaction level. in this regard, working pressure, type of job and income may affect job burnout. ergonomic interventional programs are recommended to improve the working conditions. methods this cross...

asthma  is a clinical syndrome  characterized by chronic  airway inflammation, airway responsiveness, and expiratory airflow limitation. nocturnal symptoms and decreases in lung function are common aspects of the asthma clinical syndrome. nocturnal symptoms also appear to be associated with asthma-related mortality. in addition to its importance to the regulation of human circadian rhythms, an ...

Plants have circadian oscillations in the concentration of cytosolic free calcium ([Ca(2+)](cyt)). To dissect the circadian Ca(2+)-signaling network, we monitored circadian [Ca(2+)](cyt) oscillations under various light/dark conditions (including different spectra) in Arabidopsis thaliana wild type and photoreceptor and circadian clock mutants. Both red and blue light regulate circadian oscilla...

Circadian genes are responsible for maintaining the ancient adaptation of a 24-hour circadian rhythm and influence a variety of cancer-related biological pathways, including the regulation of sex hormone levels. However, few studies have been undertaken to investigate the role of circadian genes in the development of prostate cancer, the most common cancer type among men (excluding nonmelanoma ...