• 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.

• The Korean Journal of Zoology
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• v.35 no.4
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• pp.509-517
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• 1992

LiCl (0.047 M)은 Goldhamster의 활동주기 (T)를 평균 1.6시간 연장시키고, 동물 중 20%엑서 단축되는 것으로도 관찰되었다. 1시간 통안의 빛자극(75 Lux)에 의해 주기현상 시점 변화가 나타나는 데 LICI에 의해서 0.3 h 더욱 delav되었고 advance 현상은 1.5 h 감소되었으며 delay엔h advance 전환시기는 1시간 늦게 나타났다. 반면에 7 Lux의 빛 자극에서는 delay가 2.4시간으로 더 증가되었으며 advance 현상은 2.6시간으로 저하되었고, 30분 늦게 delay에서 advance로 전환되었다. subjective day 동안에는 빛자극에 의한 LiCl 효과가 전혀 보이지 않았다. Phase-Response-Curve(PRC)는 Circadian Time에서 delay-advance로 전환되는 mid-subjective night에 점진적으로 변화되는 weak phase curve로 형성되었다. 이 PRC에서 Li이 빛에 대한 민감성을 둔화시키는 효과를 볼 수 있다.

• Journal of Korean Neurosurgical Society
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• v.62 no.5
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• pp.519-525
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• 2019

Objective : The circadian pattern of the onset time of aneurysmal subarachnoid hemorrhage (aSAH) has been reported by various authors. However, the effect of the degree of physical exertion on the circadian pattern has not been studied in detail. Therefore, we conducted this study to investigate the effect of physical exertion on the circadian pattern of aSAH. Methods : Of the 335 patients presenting with aSAH from January 2012 to December 2017, 234 patients with identifiable onset time and metabolic equivalent (MET) values were enrolled. The onset time of aSAH was divided into 4-hour intervals. The patient's physical exertion was then assessed on a scale between 1 and 8 METs using generally accepted MET values, and categorized into two groups-light exertion (1 to 4 METs) and moderate to heavy exertion (5 to 8 METs)-to determine the effect of the degree of physical exertion on the onset time distribution of aSAH. Multivariate analysis was used to calculate the odds ratio (OR) between the two groups to determine the effect of the degree of physical exertion on each set of time periods. Results : There was a definite bimodal onset pattern that peaked at 08:00-12:00 hours followed by 16:00-20:00 hours (p<0.001). MET values at all time intervals were found to be significantly higher than the night time (00:00-04:00 hours) values (p<0.031). The MET value distribution showed a unimodal pattern that slightly differed from the bimodal distribution of the onset time of aSAH. There were no significant differences in the ORs of each time interval according to the degree of the MET value. Conclusion : This study reaffirmed that aSAH occurs in a bimodal pattern, especially showing the highest prevalence in the morning. Although aSAH could be related to daily activity, there were no significant changes in diurnal variations affected by the degree of physical exertion.

• Journal of Plant Biology
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• v.25 no.1
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• pp.21-36
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• 1982

The activity of photosystem II in isolated chloroplast form the leaves of Sedum sarmentosum was measured. The photoreduction rate of DCPIP by photosystem II showed the circadian rhythm with a peak at near midday sample for a continuing fine day and at near afternoon between nidday and sunset sample for a continuing cloudy day in summer. The optimum light intensity of photoreduction by photosystem II in the chloroplast preparation was about 5~9$\times$$10^4$ lux. The saturated light intensity was over 9$\times$$10^1$lux. Photosystem II activity was inhibited by even the lowest concentration of lead. When Pi and ATP of the same concentration as Pb were added to the reaction mixture containing Tris buffer lacking of Pi prior to Pb incubation, photosystem II activity was protected from Pb-inhibiting effect by the pretreament of Pi and ATP. It was assumed that Pb inhibiiton was probably due to one, P-depriving by the precipitates of $Pb_3$ $($Pb_4$)_2$ in the reaction mixture and the other, partially Pb-combing with Pi groups of the active site of photosystem II.

• Journal of Korean Academy of Nursing
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• v.39 no.3
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• pp.422-432
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• 2009

Purpose: In this study rest-activity rhythm, sleep pattern and quality of life of patients with restless legs syndrome were compared with those of a normal group. Methods: The participants in this study were 36 patients with restless legs syndrome diagnosed by a neurologist and 36 participants in the normal group. An actigraph, sleep diary, Pittsburgh Sleep Quality Index and Insomnia Severity Index scale were used as measurement tools for the study. Chi-square test, Lamda test, t-test and Kendall's correlation with SPSS 12.0 program were used to analyze the data. Results: Patients with restless legs syndrome had a higher rest-activity rhythm curve of Least 5 hr's activity(L5) and Most 10 hr's activity(M10) than those of normal group and sleep problems included decreased sleep efficiency and increased sleep latency, wake time and number of awakenings. The scores for the subscales of quality of life in patients with restless legs syndrome were lower than the normal group for general health, physical functioning, role limitations due to emotional problems, role limitation due to physical problems, social functioning, bodily pain, vitality and mental health. Conclusion: The results suggest that further studies are needed to identify rest-activity rhythm according to symptom severity and to develop nursing interventions which consider rest-activity rhythm.

• Journal of East-West Nursing Research
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• v.25 no.1
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• pp.17-25
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• 2019

Purpose: This study investigated the factors influencing sleep quality in adults according to age groups. The escriptive study was conducted in metropolitan areas of South Korea to control for possible sleep differences between adults living in rural areas and those living in cities. Participants were 450 adults between 19 and 65 years old. Methods: Self-administered questionnaires consisting of including the Korean Modified Sleep Leeds Evaluation Questionnaire, the International Physical Activity Questionnaire and the Perceived Stress Scale were used to assess the quality of adults' sleep. Results: Sleep quality was poor across the all age groups Stress and subjective health status were influencing factors of sleep quality among participants in their 20s; subjective health status and circadian rhythm (evening-type) were influencing factors of those in their 30s; subjective health status, alcohol consumption, and work days of less than 8 hours were influencing factors among participants in their 40s; and stress, circadian rhythm (evening-type), subjective health status, work days of over 11 hours, past smoking habit, and light physical activity were influencing factors of those aged 50 years and over. Conclusion: The quality of sleep was low across the all adult age groups in South Korea. Although the factors influencing quality of sleep differed by age groups, they in general indicate the need to focus on maintaining and controlling health status in sleep interventions.

• The Korean Journal of Physiology
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• v.1 no.1
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• pp.43-49
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• 1967

Nine male rats in which 90% or more of the hippocampal tissue was removed through a small hole made in the neocortex at the boundary between the parietal and the occipital lobes (hippocampal group), 3 male rats with similar neocortical damage alone (operated control group), and 9 normal control male rats (normal control group) were prepared. Their general activity was measured for 48 hours in an activity cage by recording the number of beams they interrupted. The amount of food and water intake was also checked simultaneously. Results obtained were as follows: 1. The general activity of the hippocampal group was 2 to 3 times as great as that of the operated control or the normal control group. 2. All of the 3 groups demonstrated clear-cut circadian variation of activity, the diurnal and the nocturnal activity being in the ratio 22 : 78. 3. The amount of food and water consumed by the hippocampal group did not differ significantly from that by the opperated control or the normal control group. In the course of the experiment which continued for 3 months the hippocampal group gained weight least among the 3 groups.

• Animal cells and systems
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• v.6 no.4
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• pp.293-299
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• 2002

We investigated seasonal variation of diurnal activity patterns in Jeiu ponies (Equus caballus). The data were collected from a semi-natural herd during daylight hours from March to September 1998. Over all months the mean proportion of time spent grazing was 83.7% ( $\pm$29.7 S.D.): that resting was 15.7$\pm$17%, grooming 0.7$\pm$1.2%, and moving 0.56$\pm$5.4%, Activity patterns varied with the seasons. The mean proportion of grazing mares peaked during late winter and early spring (March), when there was not enough food, and declined during other seasons (between May and September), when food was abundant. The mean proportion of mares that were resting and mutual grooming peaked in spring (April and May), at which time the weather was warm and food became abundant. During other seasons when grasses started to grow and the weather was mildly cool, these activities were less common. The mean proportion of mares that were moving peaked in June, although it was a small proportion of the total activity. For those mares without foals, resting periods were longer in older mares than in younger mares, but for the mares with foals this pattern was not evident. From these data, we hypothesize that the dominance hierarchy of the mares effects the diurnal activity pattern.

• Journal of Photoscience
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• v.9 no.2
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• pp.252-254
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• 2002

Djungarian hamsters show distinct seasonal rhythms in several physiological parameters. One of them is daily torpor that occurs in winter with decreased body temperature (about 1O-20$^{\circ}$C) during daytime. Daily torpor is induced by short-day photoperiod, food restriction and castration. But the mechanism to induce daily torpor has not been clarified. In the present study, we tried to clarify the process of daily torpor induction in detail. Adult male hamsters were kept in long photoperiod and high temperature (LP-HT) before the experiment and, thereafter, the animals were transferred to short photoperiod and low temperature (SP-LT), and they were kept in this condition for about six months. The daily rhythms of locomotor activity and body temperature were recorded every three-minutes by using the Minimitter telemetry system. Locomotor activity and body temperature showed very closely synchronized rhythms. All animals under LP-HT showed daily rhythms with higher locomotor activity and body temperature in nighttime than in daytime. Under SP-LT, there were two types of animals with and without showing daily torpor. Thus, they have individual differences in the response to SP -LT.

• Journal of Photoscience
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• v.9 no.2
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• pp.29-32
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• 2002

Studies till date suggest the existence of a fetal biological clock in suprachiasmatic nuclei entrained by the circadian signal from mother. Melatonin from maternal pineal gland reaches to the fetus by crossing every biological barrier including placenta, hence fetuses were exposed to similar melatonin variation as their mother. Experimental modulations of maternal pineal gland activity of pregnant females either by exposing the them to different photoperiodic schedules or by exogenous melatonin treatments till the date of parturition, regulated the fetal plasma level of melatonin, thereby the prenatal (fetal) growth and development. This clearly suggests the maternal transport of melatonin to their fetus through placenta since fetal retina-hypothalamic tract was incomplete. An extension of experimental schedules till 60 days of post-partum period regulated the neonatal pineal gland activity and gonadal maturation along with their plasma levels of melatonin and sex steroids suggesting clearly the phenomenon of maternal transfer of melatonin to their young ones during the post-natal period, when the neonates were solely dependent on the mother's milk for their nutrition and energetic demands. On the basis of above observations we may suggest that the maternal pineal gland activity regulate the prenatal development by passing its melatonin to fetus via placenta and post-natal growth and sexual maturation by passing maternal melatonin to neonates via milk. Hence, the photoperiod perceived by mother is translated into the maternal plasma level of melatonin which not only regulates the prenatal but also the post-natal growth and sexual maturation of neonates.