• Science of Emotion and Sensibility
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• v.10 no.2
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• pp.253-261
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• 2007

Light is a synchronizing stimulus to regulate the circadian rhythms and neuroendocrine activities in both humans and animals. The retinohypothalamic tract is involved in the day/night cycle and neuroendocrine activities. In particular, melatonin secretion has been known to be affected by light and correlated with many aspects of health problems. This review introduces the role of the light in the biological rhythm and neuroendocrine activities, its relationship with health problems, and the characteristics of retinohypothalamic tract.

• The Journal of Korean Physical Therapy
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• v.10 no.2
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• pp.113-125
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• 1998

The neurotropic psudorabies virus(PRV) to replicate within neurons is very useful pathogen for neuronal tracing. I carried out this study to investigate the parametric analysis on the viral infection in the rat circadian control center with two genetically engineered strains out of PRV. The two strains are isogenic with the attenuated Bartha strain of PRV ; in one strain a lacZ reporter gene was inserted into the gC locus (PRV-BaBlu ; $4.75\times10^8pfu/ml$) and the other strain contained a PRV envelope glycoprotein gene(PRV-D ; $2.5\times10^8pfu/ml$) theat is absent in PRV-BaBlu. simultaneous or temporally separated sequential injection of$2{\mu}l$ of each strain into the vetreous body of eye produced a course of transsynaptic infection of retinohypothalamic circuitry. The results were as follows; 1. PRV-BaBlu and PRV-D infected the suprachiasmatic nucleus in hypothalamus and intergeniculate leaflet in lateral geniculate nucleus of thalamus. 2. The rate of PRV infection was dependent upon PRV strain. 3. Pre-infected neurons by PRV-D were interfered with the replication of PRV-BaBlu. 4. Dual injection of PRV-D and PRV-BaBlu showed more virulent than the parental strain.

• Biomedical Science Letters
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• v.11 no.4
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• pp.493-501
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• 2005

Circadian rhythms, time on a scale of about 24 hours, are present in a number of organisms including animals, plants, and bacteria. The control of the biochemical, physiological and behavioral processes is regulated by endogenous clocks in the suprachiasmatic nucleus (SCN). At the core of this timing mechanism is molecular machinery that are present both in the brain and in the peripheral tissues throughout the body, and even in a single cultured cell. In this study, we performed two-dimensional gel electrophoresis to figure out any correlation between protein expression patterns and the requirement of two canonical clock proteins, either mPER1 or mPER2, by comparing global protein expression profiles in livers from wildtype or mPer1/mPer2 double mutant mice. We could identify several differentially expressed protein candidates with respect to time and genotypes. Further analysis of these candidate proteins in detail in vivo will lead us to the better understanding of how circadian clock functions in mammals.

• 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.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.9-13
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• 2002

Alzheimer's disease (AD) is one of the most common and devastating dementing disorders of old age. Most AD patients showed significant alternation of sleep structure as well as cognitive deficit. Typical findings of sleep architecture in AD patients include lower sleep efficiency, higher stage 1 percentage, and greater frequency of arousals. The slowing of EEG activity is also noted. Abnormalities in REM sleep are of particular interest in AD because the cholinergic system is related to both REM sleep and AD. Several parameters representing REM sleep structure such as REM latency, the amount of REM sleep, and REM density are change in patients with AD. Especially, measurements of EEG slowing during tonic REM sleep can be used as an EEG marker for early detection of possible AD. In addition, a structural defect in the suprachiasmatic nucleus is suggested to cause various chronobiological alternations in AD. Most of alternations related to sleep make sleep disturbances common and disruptive symptoms of AD. In this article, the author reviewed the alternation of sleep structure and circadian rhythm in AD patients.

• Molecules and Cells
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• v.23 no.2
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• pp.215-219
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• 2007

In mammals light input resets the central clock of the suprachiasmatic nucleus by inducing secretion of pituitary adenylate cyclase-activating polypeptide (PACAP) from retinal ganglion cells (RGCs). We previously showed that thyroid transcription factor 1 (TTF-1), a homeodomain-containing transcription factor, specifically regulates PACAP gene expression in the rat hypothalamus. In the present study we examined the expression of TTF-1 in PACAP-synthesizing retinal cells. Fluorescence in situ hybridization (FISH) showed that it is abundantly expressed in RGCs of the superior region of the retina, but in only a small subset of RGCs in the inferior region. Double FISH experiments revealed that TTF-1 is exclusively expressed in PACAP-producing RGCs. These results suggest that TTF-1 plays a regulatory role in PACAP-expressing retinal ganglion cells.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.237-247
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• 2009

Melatonin (N-acetyl-5-methoxytryptamine) is the major neurohormone secreted during the night by the vertebrate pineal gland. The circadian pattern of pineal melatonin secretion is related to the biological clock within the suprachiasmatic nucleus (SCN) of the hypothalamus in mammals. The SCN coordinates the body's rhythms to the environmental light-dark cycle in response to light perceived by the retina, which acts mainly on retinal ganglion cells that contain the photopigment melanopsin. Calbindin-D9k (CaBP-9k) is a member of the S100 family of intracellular calcium- binding proteins, and in this review, we discuss the involvement of melatonin and CaBP-9k with respect to calcium homeostasis and apoptotic cell death. In future studies, we hope to provide important information on the roles played by CaBP-9k in cell signal transduction, cell proliferation, and $Ca^{2+}$ homeostasis in vivo and in vitro.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.937-942
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• 2001

The present study was conducted to identify the mechanism about the regulation of appetite by examining the expression patterns of vasoactive intestinal peptide in the hypothalamus of either fasted for 24 hours or anorexia mutant mouse. In order to investigate expression pattern of the vasoactive intestinal peptide, immunohisto-chemistry was employed along with reverse transcription polymerase chain reaction (RT-PCR) and dot blotting. Immunohistochemistry has shown that level of expression of vasoactive intestinal peptide and appetite-suppessing neuropeptide, was lower in the suprachiasmatic nucleus (SCN) and higher in the paraventricular nucleus (PVN) of the anorexia mutant group than in the comparable regions in the control group. This pattern was repeated in the fasting group, which also showed lower and higher levels of vasoactive intestinal peptide expression in the SCN and PVN respectively, In contrast, the vasoactive intestinal peptide mRNA level in the entire hypothalamus via RT-PCR and dot blotting was similar in the fasting and control groups, while it was significantly increased in the anorexia mutant group.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.70-76
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• 2005

It is known that natural awakening of us in the morning is due to stimulation of the reticular activation system through biological clock in the suprachiasmatic nucleus of hypothalamus by the morning sunlight. If we sleep at dark rooms without windows and so without morning sunlight, thus, it is not easy fur us to get up refreshingly in the morning. In this paper, we propose an automatic sunrise household lighting system that helps us fer getting up cheerfully in the morning even if we sleep in dark rooms without morning sunlight. The proposed lighting system is an embedded system that turns automatically on the electric lamp and makes it brighter and brighter coincidently with the actual sunrise. The proposed system is composed of a PIC microcontroller with flash memory, a real-time clock IC, a D/A converter, an amplifier, a dimmer unit, a light bulb, a display panel and a keyboard. The validity of the proposed intelligent lighting system is demonstrated via a prototype production and experimentation.

• Biomedical Science Letters
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• v.12 no.1
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• pp.53-56
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• 2006

The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the circadian pacemaker entrained to the 24-hr day by environmental time cues. Major circadian genes such as mPeriod ($mPer1{\sim}3$) and mCryptochrome ($mCry1{\sim}2$) are actively transcribed by the action of CLOCK/BMAL heterodimers, and in turn, these are being suppressed by the mPER/mCRY complex. In the study, the locomotor activity rhythms of mPer1 Knockout (KO) mice are measured, and the expression profiles of Heat Shock Protein 105kDa (HSP 105) genes in the SCN were measured by in situ hybridization. In agreement with previous reports, the locomotor activity rhythm of mPer1 KO mice was much shorter than that of wildtype. In addition, the total bout of activity of mPer1 KO was less in comparison to control mice. The expression of HSP 105 in the SCN of mPer1 KO mice was ranged from CT6 to CT22, with a peak level at CT14, implying that the gene are under the control of circadian clock. However, the expression of HSP 105 in the SCN of wildtype could not be detected in our study. Further analysis will reveal the direct or indirect regulation by mPer1 on the expression in the SCN and the role of the gene in the circadian clock.