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Circadian rhythms

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https://www.readbyqxmd.com/read/28646790/the-effects-of-individual-biological-rhythm-differences-on-sleep-quality-daytime-sleepiness-and-dissociative-experiences
#1
Yavuz Selvi, Ali Kandeger, Murat Boysan, Nursel Akbaba, Ayca A Sayin, Emine Tekinarslan, Basak O Koc, Omer F Uygur, Vedat Sar
Individuals who differ markedly by sleep chronotype, i.e., morning-type or evening-type also differ on a number of psychological, behavioral, and biological variables. Among several other psychological functions, dissociation may also lead to disruption and alteration of consciousness, which may facilitate dream-like experiences. Our study was aimed at an inquiry into the effects of individual biological rhythm differences on sleep quality and daytime sleepiness in conjunction with dissociative experiences...
June 17, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28645689/duration-and-timing-of-daily-light-exposure-influence-the-rapid-shifting-of-balb-cj-mouse-circadian-locomotor-rhythms
#2
Thomas J Vajtay, Jeremy J St Thomas, Tyrus E Takacs, Eric G McGann, E Todd Weber
Photic entrainment of the murine circadian system can typically be explained with a discrete model in which light exposures near dusk and dawn can either advance or delay free-running rhythms to match the external light cycle period. In most mouse strains, the magnitude of those phase shifts is limited to several hours per day; however, the BALB/cJ mouse can re-entrain to large (6-8hour) phase advances of the light/dark cycle. In this study, we demonstrate that the circadian responses of BALB/cJ mice are dependent on duration as well as timing of light exposure, with significantly larger phase shifts resulting from >6-hour light exposures, yet loss of entrainment to photoperiods of <2-3h per day or to skeleton photoperiods...
June 20, 2017: Physiology & Behavior
https://www.readbyqxmd.com/read/28645331/circadian-clock-gene-polymorphisms-in-relation-to-sleep-patterns-and-obesity-in-african-americans-findings-from-the-jackson-heart-study
#3
Pia Riestra, Samson Y Gebreab, Ruihua Xu, Rumana J Khan, Amadou Gaye, Adolfo Correa, Nancy Min, Mario Sims, Sharon K Davis
BACKGROUND: Circadian rhythms regulate key biological processes and the dysregulation of the intrinsic clock mechanism affects sleep patterns and obesity onset. The CLOCK (circadian locomotor output cycles protein kaput) gene encodes a core transcription factor of the molecular circadian clock influencing diverse metabolic pathways, including glucose and lipid homeostasis. The primary objective of this study was to evaluate the associations between CLOCK single nucleotide polymorphisms (SNPs) and body mass index (BMI)...
June 23, 2017: BMC Genetics
https://www.readbyqxmd.com/read/28644109/the-timing-of-gigantea-expression-during-day-night-cycles-varies-with-the-geographical-origin-of-arabidopsis-accessions
#4
Amaury de Montaigu, George Coupland
Latitudinal clines in circadian rhythms have consistently been described in various plant species, with the most recent examples appearing in soybean cultivars and in monkey flower natural populations. These latitudinal clines provide evidence that natural variation in circadian rhythms is adaptive, but it is still unclear what adaptive benefits this variation confers, particularly because circadian rhythms are not usually measured in day/night conditions that reflect those experienced by organisms in nature...
June 23, 2017: Plant Signaling & Behavior
https://www.readbyqxmd.com/read/28643108/integrated-tk-td-modeling-for-drug-induced-concurrent-tachycardia-and-qt-changes-in-beagle-dogs
#5
Fan Wu, Tycho Heimbach, Panos Hatsis, Hai-Ming Tang, Raviprakash Dugyala, Qin Yue, Tao Wang, Handan He
Drug-induced cardiotoxicity, including tachycardia and QT prolongation, remains a major safety concern that needs to be identified and its risk mitigated in early stages of drug development. In the present study, an integrated toxicokinetic-toxicodynamic (TK-TD) modeling approach within a nonlinear mixed-effect modeling framework is applied to investigate concurrent abnormal heart rate and QT changes in three beagle dogs, using a Novartis internal compound (NVS001) as the case example. By accounting for saturable drug absorption, circadian rhythms, drug-effect tolerance, and nonlinear rate-dependency of QT interval, the dynamic TK-TD model captures the experimentally observed drug effects on heart rate and QT interval across a wide dosing range of NVS001 in beagle dogs...
June 22, 2017: Journal of Pharmacokinetics and Pharmacodynamics
https://www.readbyqxmd.com/read/28638438/real-time-monitoring-of-ptahmgb-activity-in-poplar-transactivation-assays
#6
José M Ramos-Sánchez, Paolo M Triozzi, Alicia Moreno-Cortés, Daniel Conde, Mariano Perales, Isabel Allona
BACKGROUND: Precise control of gene expression is essential to synchronize plant development with the environment. In perennial plants, transcriptional regulation remains poorly understood, mainly due to the long time required to perform functional studies. Transcriptional reporters based on luciferase have been useful to study circadian and diurnal regulation of gene expression, both by transcription factors and chromatin remodelers. The high mobility group proteins are considered transcriptional chaperones that also modify the chromatin architecture...
2017: Plant Methods
https://www.readbyqxmd.com/read/28637495/diurnal-variation-in-the-core-interthreshold-zone-and-its-relation-to-cutaneous-sensation-threshold-zone
#7
Naoshi Kakitsuba, Igor B Mekjavic
BACKGROUND: The core interthreshold zone (CIZ) is defined as the range between temperatures at the onset of shivering and sweating. Its circadian or diurnal variation has not been extensively studied. The present study examined whether the CIZ is subject to a diurnal rhythm. In addition, according to the previous finding that the CIZ was proportionally correlated with peripheral interthreshold zone (PIZ), it was also examined whether cutaneous sensation threshold zone (CSZ), a determinant of the PIZ, is correlated with the CIZ...
June 21, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/28636777/biological-effects-related-to-geomagnetic-activity-and-possible-mechanisms
#8
REVIEW
Viacheslav V Krylov, Margaret Larkin
This review presents contemporary data on the biological effects of geomagnetic activity. Correlations between geomagnetic indices and biological parameters and experimental studies that used simulated geomagnetic storms to detect possible responses of organisms to these events in nature are discussed. Possible mechanisms by which geomagnetic activity influences organisms are also considered. Special attention is paid to the idea that geomagnetic activity is perceived by organisms as a disruption of diurnal geomagnetic variation...
June 21, 2017: Bioelectromagnetics
https://www.readbyqxmd.com/read/28636610/chronotypes-in-the-us-influence-of-age-and-sex
#9
Dorothee Fischer, David A Lombardi, Helen Marucci-Wellman, Till Roenneberg
An individual's chronotype reflects how the circadian system embeds itself into the 24-h day with rhythms in physiology, cognition and behavior occurring accordingly earlier or later. In view of an increasing number of people working at unusual times and linked health and safety risks, the wide range in human chronotypes may provide opportunities to allow people to work (and sleep) at times that are in synch with their circadian physiology. We aimed at estimating the distribution of chronotypes in the US population by age and sex...
2017: PloS One
https://www.readbyqxmd.com/read/28634329/long-days-enhance-recognition-memory-and-increase-insulin-like-growth-factor-2-in-the-hippocampus
#10
Adriano Dellapolla, Ian Kloehn, Harshida Pancholi, Ben Callif, David Wertz, Kayla E Rohr, Matthew M Hurley, Kimberly M Baker, Samer Hattar, Marieke R Gilmartin, Jennifer A Evans
Light improves cognitive function in humans; however, the neurobiological mechanisms underlying positive effects of light remain unclear. One obstacle is that most rodent models have employed lighting conditions that cause cognitive deficits rather than improvements. Here we have developed a mouse model where light improves cognitive function, which provides insight into mechanisms underlying positive effects of light. To increase light exposure without eliminating daily rhythms, we exposed mice to either a standard photoperiod or a long day photoperiod...
June 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28633442/continuous-glucose-monitoring-in-female-nod-mice-reveals-daily-rhythms-and-a-negative-correlation-with-body-temperature
#11
Ron Korstanje, Jennifer L Ryan, Holly S Savage, Bonnie L Lyons, Kevin G Kane, Stacey J Sukoff Rizzo
Previous studies with continuous glucose monitoring in mice have been limited to several days or weeks, with the mouse's physical attachment to the equipment impacting behavior and measurements. In the current study we measured blood glucose and body temperature at 10-second intervals for 12 weeks in a cohort of NOD/ShiLtJ female mice using wireless telemetry. This allowed us, for the first time, to obtain a high-resolution profile of the circadian rhythm of these two parameters and the onset of hyperglycemic development in real time...
June 19, 2017: Endocrinology
https://www.readbyqxmd.com/read/28632163/melatonin-as-a-novel-interventional-candidate-for-fragile-x-syndrome-with-autism-spectrum-disorder-in-humans
#12
REVIEW
Jinyoung Won, Yunho Jin, Jeonghyun Choi, Sookyoung Park, Tae Ho Lee, Sang-Rae Lee, Kyu-Tae Chang, Yonggeun Hong
Fragile X syndrome (FXS) is the most common monogenic form of autism spectrum disorder (ASD). FXS with ASD results from the loss of fragile X mental retardation (fmr) gene products, including fragile X mental retardation protein (FMRP), which triggers a variety of physiological and behavioral abnormalities. This disorder is also correlated with clock components underlying behavioral circadian rhythms and, thus, a mutation of the fmr gene can result in disturbed sleep patterns and altered circadian rhythms. As a result, FXS with ASD individuals may experience dysregulation of melatonin synthesis and alterations in melatonin-dependent signaling pathways that can impair vigilance, learning, and memory abilities, and may be linked to autistic behaviors such as abnormal anxiety responses...
June 20, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28630482/circadian-and-circatidal-clocks-control-the-mechanism-of-semilunar-foraging-behaviour
#13
James F Cheeseman, Rachel M Fewster, Michael M Walker
How animals precisely time behaviour over the lunar cycle is a decades-old mystery. Experiments on diverse species show this behaviour to be endogenous and under clock control but the mechanism has remained elusive. We present new experimental and analytical techniques to test the hypotheses for the semilunar clock and show that the rhythm of foraging behaviour in the intertidal isopod, Scyphax ornatus, can be precisely shifted by manipulating the lengths of the light/dark and tidal cycles. Using light T-cycles (Tcd) the resultant semilunar beat period undergoes shifts from 14...
June 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28630378/randomised-controlled-trial-of-the-efficacy-of-a-blue-enriched-light-intervention-to-improve-alertness-and-performance-in-night-shift-workers
#14
Tracey L Sletten, Suzanne Ftouni, Christian L Nicholas, Michelle Magee, Ronald R Grunstein, Sally Ferguson, David J Kennaway, Darren O'Brien, Steven W Lockley, Shantha M W Rajaratnam
OBJECTIVES: Night workers often experience high levels of sleepiness due to misalignment of the sleep-wake cycle from the circadian pacemaker, in addition to acute and chronic sleep loss. Exposure to light, in particular short wavelength light, can improve alertness and neurobehavioural performance. This randomised controlled trial examined the efficacy of blue-enriched polychromatic light to improve alertness and neurobehavioural performance in night workers. DESIGN: Participants were 71 night shift workers (42 males; 32...
June 19, 2017: Occupational and Environmental Medicine
https://www.readbyqxmd.com/read/28630025/the-clock-is-ticking-ageing-of-the-circadian-system-from-physiology-to-cell-cycle
#15
REVIEW
Eva Terzibasi-Tozzini, Antonio Martinez-Nicolas, Alejandro Lucas-Sánchez
The circadian system is the responsible to organise the internal temporal order in relation to the environment of every process of the organisms producing the circadian rhythms. These rhythms have a fixed phase relationship among them and with the environment in order to optimise the available energy and resources. From a cellular level, circadian rhythms are controlled by genetic positive and negative auto-regulated transcriptional and translational feedback loops, which generate 24hour rhythms in mRNA and protein levels of the clock components...
June 16, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28629592/measurement-and-clinical-utility-of-%C3%AE-ctx-in-serum-and-plasma
#16
Stephen A P Chubb, Samuel D Vasikaran
Biochemical markers of bone turnover (BTM) are released during bone remodeling and can be measured in blood or urine as noninvasive surrogate markers for the bone remodeling rate. The C-terminal cross-linked telopeptide of type I collagen (βCTX) is released during bone resorption and is specific to bone tissue. Assays have been developed to measure βCTX in blood and in urine; most current use of βCTX measurement for research and in clinical practice is performed on a blood sample. Method-specific differences for serum and plasma βCTX have led to initiatives to standardize or harmonize βCTX commercial assays...
2017: Advances in Clinical Chemistry
https://www.readbyqxmd.com/read/28626420/restless-legs-syndrome-from-pathophysiology-to-clinical-diagnosis-and-management
#17
REVIEW
Shiyi Guo, Jinsha Huang, Haiyang Jiang, Chao Han, Jie Li, Xiaoyun Xu, Guoxin Zhang, Zhicheng Lin, Nian Xiong, Tao Wang
Restless legs syndrome (RLS), a common neurological sensorimotor disorder in western countries, has gained more and more attention in Asian countries. The prevalence of RLS is higher in older people and females. RLS is most commonly related to iron deficiency, pregnancy and uremia. The RLS symptoms show a significant circadian rhythm and a close relationship to periodic limb movements (PLMs) in clinical observations, while the pathophysiological pathways are still unknown. The diagnostic criteria have been revised in 2012 to improve the validity of RLS diagnosis...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28626157/protein-restriction-does-not-affect-body-temperature-pattern-in-female-mice
#18
Goro A Kato, Hiroki Shichijo, Toshihiro Takahashi, Akio Shinohara, Tetsuo Morita, Chihiro Koshimoto
Daily torpor is a physiological adaptation in mammals and birds characterized by a controlled reduction of metabolic rate and body temperature during the resting phase of circadian rhythms. In laboratory mice, daily torpor is induced by dietary caloric restriction. However, it is not known which nutrients are related to daily torpor expression. To determine whether dietary protein is a key factor in inducing daily torpor in mice, we fed mice a protein-restricted (PR) diet that included only one-quarter of the amount of protein but the same caloric level as a control (C) diet...
June 13, 2017: Experimental Animals
https://www.readbyqxmd.com/read/28625682/are-circadian-rhythms-new-pathways-to-understand-autism-spectrum-disorder
#19
M-M Geoffray, A Nicolas, M Speranza, N Georgieff
Autism Spectrum Disorder (ASD) is a frequent neurodevelopmental disorder. ASD is probably the result of intricate interactions between genes and environment altering progressively the development of brain structures and functions. Circadian rhythms are a complex intrinsic timing system composed of almost as many clocks as there are body cells. They regulate a variety of physiological and behavioral processes such as the sleep- wake rhythm. ASD is often associated with sleep disorders and low levels of melatonin...
June 15, 2017: Journal of Physiology, Paris
https://www.readbyqxmd.com/read/28625385/seasonal-and-circadian-variations-of-acute-myocardial-infarction-findings-from-the-get-with-the-guidelines-coronary-artery-disease-gwtg-cad-program
#20
Vijaiganesh Nagarajan, Gregg C Fonarow, Christine Ju, Michael Pencina, Warren K Laskey, Thomas M Maddox, Adrian Hernandez, Deepak L Bhatt
BACKGROUND: Seasonal variation with winter preponderance of myocardial infarction incidence has been described decades ago, but only a few small studies have classified myocardial infarction based on ST-segment elevation. It is unclear whether seasonal and circadian variations are equally present in warmer and colder regions. We investigated whether seasonal and circadian variations in acute myocardial infarction (AMI) are more prominent in colder northern states compared with warmer southern states...
July 2017: American Heart Journal
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