• Sleep Medicine and Psychophysiology
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• v.21 no.2
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• pp.51-60
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• 2014

A 'circadian rhythm' is a self-sustained biological rhythm (cycle) that repeats itself approximately every 24 hours. Circadian rhythms are generated by an internal clock, or pacemaker, and persist even in the absence of environmental time cues, collectively termed 'zeitgebers.' Although organisms generate circadian rhythms internally, they are entrained by environmental stimuli, particularly the light-dark cycle. Measurement of the endogenous melatonin rhythm provides relatively reliable surrogate way of assessing the timing of the internal circadian clock. Also, core body temperature and cortisol can be used as markers of circadian rhythms. The sleep-wake cycle, body temperature, and melatonin rhythm have a stable internal phase relationship in humans and other diurnal species. They play an important role in controlling daily behavioral rhythms including task performance, blood pressure, and synthesis and secretion of several hormones. In this review, we address not only the properties, methods of measurement, and markers of circadian rhythms, but also the physiological and psychological importance of human circadian rhythms.

• The Journal of Internal Korean Medicine
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• v.31 no.4
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• pp.829-836
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• 2010

Purpose : This study investigated the diurnal rhythm of cortisol in male and female adolescents. Methods : Salivary cortisol was examined in 52 normally developing subjects aged 13 to 14 years. Subjects provided saliva samples at 08:00h, 12:00h, 16:00h and 20:00h. Results : Males and females showed similar pattern of cortisol, which elevated cortisol in the morning and decreased in the evening. There were no differences of gender at 08:00h, 12;00h and 20:00h. There were also not difference between males and females using an area under the curve analysis. Conclusions : The same diurnal cortisol rhythm were found in male and female adolescents. Further research is needed to examine differences of gender in cortisol awakening response.

• Korean Circulation Journal
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• v.48 no.12
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• pp.1033-1080
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• 2018

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in the general population. The Korean Heart Rhythm Society organized a Korean AF Management Guideline Committee and analyzed all available studies regarding the management of AF, including studies on Korean patients. This guideline is based on recent data of the Korean population and the recent guidelines of the European Society of Cardiology, European Association for Cardio-Thoracic Surgery, American Heart Association, and Asia Pacific Heart Rhythm Society. Expert consensus or guidelines for the optimal management of Korean patients with AF were achieved after a systematic review with intensive discussion. This article provides general principles for appropriate risk stratification and selection of anticoagulation therapy in Korean patients with AF. This guideline deals with optimal stroke prevention, screening, rate and rhythm control, risk factor management, and integrated management of AF.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.358-367
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• 2018

Most organisms have adapted to a circadian rhythm that follows a roughly 24-hour cycle, which is modulated by both internal (clock-related genes) and external (environment) factors. In such organisms, the central nervous system (CNS) is influenced by the circadian rhythm of individual cells. Furthermore, the period circadian clock 2 (Per2) gene is an important component of the circadian clock, which modulates the circadian rhythm. Per2 is mainly expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus as well as other brain areas, including the midbrain and forebrain. This indicates that Per2 may affect various neurobiological activities such as sleeping, depression, and addiction. In this review, we focus on the neurobiological functions of Per2, which could help to better understand its roles in the CNS.

• Journal of Veterinary Clinics
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• v.27 no.4
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• pp.440-444
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• 2010

A 7-year-old neutered male Shih Tzu dog weighing 5.2 kg was presented because of severe neurological signs (paddling, unconsciousness, blindness, seizure). ECG revealed accelerated idioventricular rhythm (AIVR) with ~140 bpm ventricular rate. Based on magnetic resonance imaging (MRI) study and cerebrospinal fluid (CSF) analysis, the neurological condition was tentatively diagnosed as disseminated granulomatous meningoencephalomyelitis (GME). The neurological signs were managed with steroids, anticonvulsive drugs, diuretics and antibiotics with 20% mannitol infusion. The rhythm disturbance (AIVR) was managed with oral medication of mexiletine. Because the heart rhythms were unstable without anti-arrhythmic therapy in spite of improvement of clinical signs after emergency treatment for neurological problems, the anti-arrhythmic therapy was maintained till the neurological signs were abolished.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.405-413
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• 2012

Low misclassification performance is significant with high classification accuracy for a reliable diagnosis of ECG signals, and diagnosing abnormal state as normal state can especially raises a deadly problem to a person in ECG test. In this paper, we propose detection and classification method of abnormal rhythm by rule-based rhythm classification reflecting clinical criteria for disease. Rule-based classification classifies rhythm types using rule-base for feature of rhythm section, and rule-base deduces decision results corresponding to professional materials of clinical and internal fields. Experimental results for the MIT-BIH arrhythmia database show that the applicability of proposed method is confirmed to classify rhythm types for normal sinus, paced, and various abnormal rhythms, especially without misclassification in detection aspect of abnormal rhythm.

• Molecules and Cells
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• v.40 no.7
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• pp.450-456
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• 2017

Mammalian physiology and behavior are regulated by an internal time-keeping system, referred to as circadian rhythm. The circadian timing system has a hierarchical organization composed of the master clock in the suprachiasmatic nucleus (SCN) and local clocks in extra-SCN brain regions and peripheral organs. The circadian clock molecular mechanism involves a network of transcription-translation feedback loops. In addition to the clinical association between circadian rhythm disruption and mood disorders, recent studies have suggested a molecular link between mood regulation and circadian rhythm. Specifically, genetic deletion of the circadian nuclear receptor Rev-$erb{\alpha}$ induces mania-like behavior caused by increased midbrain dopaminergic (DAergic) tone at dusk. The association between circadian rhythm and emotion-related behaviors can be applied to pathological conditions, including neurodegenerative diseases. In Parkinson's disease (PD), DAergic neurons in the substantia nigra pars compacta progressively degenerate leading to motor dysfunction. Patients with PD also exhibit non-motor symptoms, including sleep disorder and neuropsychiatric disorders. Thus, it is important to understand the mechanisms that link the molecular circadian clock and brain machinery in the regulation of emotional behaviors and related midbrain DAergic neuronal circuits in healthy and pathological states. This review summarizes the current literature regarding the association between circadian rhythm and mood regulation from a chronobiological perspective, and may provide insight into therapeutic approaches to target psychiatric symptoms in neurodegenerative diseases involving circadian rhythm dysfunction.

• Journal of Oral Medicine and Pain
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• v.40 no.3
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• pp.89-95
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• 2015

All living organisms have a biological clock that orchestrates every biological process and function, and this internal clock operates following a circadian rhythm. This biological clock is known to influence various clinical indicators such as blood pressure and body temperature. Also, the fluctuation of signs and symptoms of diseases including pain disorders are affected by circadian rhythm. It has been reported that the pain intensity of various somatic and neuropathic pain disorders show unique pain patterns that depend on the passage of time. The generation of pain patterns could be explained by extrinsic (e.g., physical activity, tactile stimulation, ambient temperature) and also intrinsic factors (neural and neuroendocrine modulation) that are related to the circadian rhythm. It is important to recognize and identify the individual pain pattern in pain therapy to approve treatment outcome. Moreover, chronotherapeutics which considers pain patterns and pharmacokinetics in context of the circadian rhythm could produce greater analgesia in response to medication. However, only a limited number of studies handle the issue of pain patterns according to circadian rhythm and chronotherapeutics in the orofacial region. The present review intends to reflect on the most recent and relevant data concerning the bidirectional relation between pain disorders of the orofacial region and circadian patterns.

• Sleep Medicine and Psychophysiology
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• v.20 no.1
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• pp.10-14
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• 2013

Sleep disturbances are commonly encountered problems in cancer patients. Sleep has a role in maintenance of immunity, metabolism, and quality of life but little has been known about the prevalence, risk factors, and effects on prognosis of sleep disturbances in patients with cancer. Also little attention has been made on proper assessment and management of sleep disorders in these patients. Recently, there have been some reports that sleep disorders are related with development of many cancers such as breast, colorectal, prostate, and endometrial cancers. An intermittent hypoxia and a disruption of circadian rhythm are considered as one of the possible mechanisms of cancer developments. More aggressive evaluation and meticulous management of sleep disturbances in cancer patients are essential to improve quality of life as well as prognosis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.2
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• pp.222-228
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• 1984

Since organisms have their rhythms by synchronizing the changes of periodic external circumstances and maintaining the integration of internal ones, circadian rhythm which affects to ingestion, digestion and metabolism of nutrients in the body, is important and interesting to discuss in the field of nutritional science. Also it is a serious public health problem tat various night-shift jobs are increasing now a days. Therefore authors wish to understand the properties of circadian rhythm and the rhythms of metabolic activities.