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Industrial Health Sep 2019The master clock of the biological rhythm, located in the suprachiasmatic nucleus of the anterior hypothalamus, synchronizes the molecular biological clock found in... (Review)
Review
The master clock of the biological rhythm, located in the suprachiasmatic nucleus of the anterior hypothalamus, synchronizes the molecular biological clock found in every cell of most peripheral tissues. The human circadian rhythm is largely based on the light-dark cycle. In night shift workers, alteration of the cycle and inversion of the sleep-wake rhythm can result in disruption of the biological clock and induce adverse health effects. This paper offers an overview of the main physiological mechanisms that regulate the circadian rhythm and of the health risks that are associated with its perturbation in shift and night workers. The Occupational Physician should screen shift and night workers for clinical symptoms related to the perturbation of the biological clock and consider preventive strategies to reduce the associated health risks.
Topics: Circadian Clocks; Circadian Rhythm; Humans; Light; Occupational Medicine; Sleep; Work Schedule Tolerance
PubMed: 30799323
DOI: 10.2486/indhealth.2018-0173 -
Cephalalgia : An International Journal... Dec 2019To review and discuss the putative role of light, sleep, and the biological clock in cluster headache. (Review)
Review
OBJECTIVE
To review and discuss the putative role of light, sleep, and the biological clock in cluster headache.
DISCUSSION
Cluster headache attacks are believed to be modulated in the hypothalamus; moreover, the severe pain and typical autonomic cranial features associated with cluster headache are caused by abnormal activity of the trigeminal-autonomic reflex. The temporal pattern of cluster headache attacks suggests involvement of the biological clock, and the seasonal pattern is influenced by the number of daylight hours. Although sleep is often reported as a trigger for cluster headache attacks, to date no clear correlation has been established between these attacks and sleep stage.
CONCLUSIONS
We hypothesize that light, sleep, and the biological clock can change the brain's state, thereby lowering the threshold for activating the trigeminal-autonomic reflex, resulting in a cluster headache attack. Understanding the mechanisms that contribute to the daily and seasonal fluctuations in cluster headache attacks may provide new therapeutic targets.
Topics: Biological Clocks; Circadian Rhythm; Cluster Headache; Humans
PubMed: 31142137
DOI: 10.1177/0333102419851815 -
Alcohol Research & Health : the Journal... 2001The daily light-dark cycle governs rhythmic changes in the behavior and/or physiology of most species. Studies have found that these changes are governed by a biological... (Review)
Review
The daily light-dark cycle governs rhythmic changes in the behavior and/or physiology of most species. Studies have found that these changes are governed by a biological clock, which in mammals is located in two brain areas called the suprachiasmatic nuclei. The circadian cycles established by this clock occur throughout nature and have a period of approximately 24 hours. In addition, these circadian cycles can be synchronized to external time signals but also can persist in the absence of such signals. Studies have found that the internal clock consists of an array of genes and the protein products they encode, which regulate various physiological processes throughout the body. Disruptions of the biological rhythms can impair the health and well-being of the organism.
Topics: Alcoholism; Animals; Biological Clocks; Circadian Rhythm; Gene Expression; Humans; Sleep Disorders, Circadian Rhythm; Sleep Stages; Suprachiasmatic Nucleus
PubMed: 11584554
DOI: No ID Found -
Presse Medicale (Paris, France : 1983) 2018The circadian clock has an endogenous activity, independently of environmental cues. It is also synchronized on the 24hours cycle specifically by light. The central... (Review)
Review
The circadian clock has an endogenous activity, independently of environmental cues. It is also synchronized on the 24hours cycle specifically by light. The central biological clock is located in the supra-chiasmatic nuclei of the hypothalamus. Multiple peripheral biological clocks are also identified in almost all the systems.
Topics: Adaptation, Physiological; Animals; Biological Clocks; Circadian Rhythm; Humans; Light; Photoperiod
PubMed: 30391272
DOI: 10.1016/j.lpm.2018.10.011 -
Ugeskrift For Laeger Sep 2018Daily biological rhythms are controlled by a clock system, composed of a hierarchical multi-oscillator structure. Each cell in this system harbours a self-sustained... (Review)
Review
Daily biological rhythms are controlled by a clock system, composed of a hierarchical multi-oscillator structure. Each cell in this system harbours a self-sustained autonomous molecular oscillator. Light adjusts the phase of the brain oscillator to the environmental light/dark cycle by intrinsically photosensitive retinal ganglion cells through their own photoreceptor, melanopsin, and by using the neuropeptide called pituitary adenylate cyclase-activating polypeptide as well as glutamate as neurotransmitters. The circadian synchronisation system is critical to health, and breakdown of the 24-hour temporal order could lead to pathological conditions.
Topics: Biological Clocks; Brain; Circadian Rhythm; Circadian Rhythm Signaling Peptides and Proteins; Humans; Photoperiod; Suprachiasmatic Nucleus
PubMed: 30348253
DOI: No ID Found -
Brain and Nerve = Shinkei Kenkyu No... Jun 2012Under temporal isolation, the human sleep-wake cycle occasionally desynchronizes from the circadian rhythms in deep body temperature and plasma melatonin. Such internal... (Review)
Review
Under temporal isolation, the human sleep-wake cycle occasionally desynchronizes from the circadian rhythms in deep body temperature and plasma melatonin. Such internal desynchronization is observed even in the real world. Two distinct models are advanced for the sleep-wake cycle; one is a two-oscillator model and the other is a two-process model. However, our recent studies in human subjects under temporal isolation support the former model. Internal desynchronization is unique to the human sleep-wake cycle and has been never observed in other mammal species. Therefore, a specific animal model for the human sleep-wake cycle is needed to explore the brain mechanism. By chronic treatment with methamphetamine (MAP), a stimulant of the central dopaminergic system, in drinking water, rats showed behavioral rhythms which were independent of the circadian pacemaker in the suprachiasmatic nucleus (SCN), the central clock entraining to light-dark cycles. Furthermore, MAP treatment induces internal desynchronization between the MAP-induced behavioral rhythms and the circadian rhythms of clock gene expression in the SCN, suggesting a presence of a secondary pacemaker outside the SCN that regulates the sleep-wake cycle. These findings are consistent with the two-oscillator model mentioned previously. According to the current understanding of the circadian system in mammals, there are a number of so-called peripheral clocks in the body which are regulated by the central clock in the SCN. Taking advantage of the MAP-induced internal desynchronization, attempts have been made to identity the peripheral clock(s) regulating the sleep-wake cycle. The nigrostriatal dopaminergic system is a possible site of the behavior-associated peripheral clock.
Topics: Animals; Biological Clocks; Circadian Rhythm; Humans; Models, Biological; Sleep; Suprachiasmatic Nucleus; Wakefulness
PubMed: 22647471
DOI: No ID Found -
Expert Review of Clinical Immunology May 2014Rheumatoid arthritis (RA) is an autoimmune disease of unknown cause and a chronic and progressive inflammatory disorder ensuing in genetically predisposed subjects,... (Review)
Review
Rheumatoid arthritis (RA) is an autoimmune disease of unknown cause and a chronic and progressive inflammatory disorder ensuing in genetically predisposed subjects, characterized by synovitis causing joint destruction, as well as inflammation in body organ systems, leading to anatomical alteration and functional disability. Immune competent cells, deregulated synoviocytes and cytokines play a key role in the pathophysiological mechanisms. The immune system function shows time-related variations related to the influence of the neuroendocrine system and driven by the circadian clock circuitry. Immune processes and symptom intensity in RA are characterized by oscillations during the day following a pattern of circadian rhythmicity. A cross-talk between inflammatory and circadian pathways is involved in RA pathogenesis and underlies the mutual actions of disruption of the circadian clock circuitry on immune system function as well as of inflammation on the function of the biological clock. Modulation of molecular processes and humoral factors mediating in RA the interplay between the biological clock and the immune response and underlying the rhythmic fluctuations of pathogenic processes and symptomatology could represent a promising therapeutic strategy in the future.
Topics: Arthritis, Rheumatoid; Biological Clocks; Circadian Rhythm; Humans; Immune System; Models, Immunological; Neurosecretory Systems; Signal Transduction
PubMed: 24684672
DOI: 10.1586/1744666X.2014.899904 -
World Journal of Urology Dec 2006Do men have biological clocks that affect their hormone levels, fertility, and the genetic quality of their sperm? Women can no longer be viewed as solely responsible... (Review)
Review
Do men have biological clocks that affect their hormone levels, fertility, and the genetic quality of their sperm? Women can no longer be viewed as solely responsible for age-related fertility and genetic problems. The effects of andropause and advanced paternal age on fertility and offspring are still under investigation. Further research is needed to fully characterize the associated risks and to treat the underlying abnormalities. A better understanding of the cellular and biochemical mechanisms of "gonadal" aging is important in order to determine safe, effective ways to delay this process and "rewind" the male biological clock. The benefits may include decreasing the potential for adverse genetic consequences in offspring, improvement in the sexual and reproductive health of aging males, and increase a woman's chance of having healthy children by correcting defects in the male reproductive system.
Topics: Aging; Biological Clocks; Fertility; Humans; Male; Paternal Age
PubMed: 17082936
DOI: 10.1007/s00345-006-0130-y -
Genome Biology 2000The genetic and molecular analysis of circadian timekeeping mechanisms has accelerated as a result of the increasing volume of genomic markers and nucleotide sequence... (Review)
Review
The genetic and molecular analysis of circadian timekeeping mechanisms has accelerated as a result of the increasing volume of genomic markers and nucleotide sequence information. Completion of whole genome sequences and the use of differential gene expression technology will hasten the discovery of the clock output pathways that control diverse rhythmic phenomena.
Topics: Animals; Biological Clocks; Circadian Rhythm; Gene Expression Profiling; Models, Biological; RNA, Messenger; Signal Transduction
PubMed: 11178250
DOI: 10.1186/gb-2000-1-4-reviews1023 -
Molecular Cell Sep 2018Age-associated changes to the mammalian DNA methylome are well documented and thought to promote diseases of aging, such as cancer. Recent studies have identified... (Review)
Review
Age-associated changes to the mammalian DNA methylome are well documented and thought to promote diseases of aging, such as cancer. Recent studies have identified collections of individual methylation sites whose aggregate methylation status measures chronological age, referred to as the DNA methylation clock. DNA methylation may also have value as a biomarker of healthy versus unhealthy aging and disease risk; in other words, a biological clock. Here we consider the relationship between the chronological and biological clocks, their underlying mechanisms, potential consequences, and their utility as biomarkers and as targets for intervention to promote healthy aging and longevity.
Topics: Aging; Animals; Biological Clocks; Cellular Senescence; CpG Islands; DNA Methylation; Epigenesis, Genetic; Humans; Longevity
PubMed: 30241605
DOI: 10.1016/j.molcel.2018.08.008