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Circadian rhythm

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https://www.readbyqxmd.com/read/28226828/a-mathematical-model-of-ultradian-sleep-wake-regulation-in-rodents
#1
Hao Wang, Farid Yaghouby, Sridhar Sunderam, Hao Wang, Farid Yaghouby, Sridhar Sunderam, Sridhar Sunderam, Farid Yaghouby, Hao Wang
Rodent models are widely used for the experimental analysis of sleep. While this is motivated by similarities in brain circuitry and electrophysiological rhythms, unlike the circadian sleep-wake cycle in humans, rodent sleep is polyphasic, containing multiple bouts of sleep and wake minutes to hours in duration over the course of a day. Each sleep bout is punctuated by several brief arousals several seconds to minutes long. Physiologically motivated mathematical models replicate the shorter timescale of arousal within sleep, but not the longer one representing prolonged wakefulness...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28224616/critical-cholangiocarcinogenesis-control-by-cryptochrome-clock-genes
#2
Ali Mteyrek, Elisabeth Filipski, Catherine Guettier, Malgorzata Oklejewicz, Gijsbertus T J van der Horst, Alper Okyar, Francis Lévi
A coordinated network of molecular circadian clocks in individual cells generates 24-hour rhythms in liver metabolism and proliferation. Circadian disruption through chronic jet lag or Per2 clock gene mutation was shown to accelerate hepatocarcinoma development in mice. Since divergent effects were reported for clock genes Per and Cry regarding xenobiotic toxicity, we questioned the role of Cry1 and Cry2 in liver carcinogenesis. Male WT and Cry1(-/-) Cry2(-/-) mice (C57Bl/6 background) were chronically exposed to diethylnitrosamine (DEN) at ZT11...
February 22, 2017: International Journal of Cancer. Journal International du Cancer
https://www.readbyqxmd.com/read/28223912/diet-induced-obesity-and-circadian-disruption-of-feeding-behavior
#3
REVIEW
Aurea Blancas-Velazquez, Jorge Mendoza, Alexandra N Garcia, Susanne E la Fleur
Feeding behavior shows a rhythmic daily pattern, which in nocturnal rodents is observed mainly during the dark period. This rhythmicity is under the influence of the hypothalamic suprachiasmatic nucleus (SCN), the main biological clock. Nevertheless, various studies have shown that in rodent models of obesity, using high-energy diets, the general locomotor activity and feeding rhythms can be disrupted. Here, we review the data on the effects of diet-induced obesity (DIO) on locomotor activity and feeding patterns, as well as the effect on the brain sites within the neural circuitry involved in metabolic and rewarding feeding behavior...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28223222/disrupting-the-key-circadian-regulator-clock-leads-to-age-dependent-cardiovascular-disease
#4
Faisal J Alibhai, Jonathan LaMarre, Cristine J Reitz, Elena V Tsimakouridze, Jeffrey T Kroetsch, Steffen-Sebastian Bolz, Alex Shulman, Samantha Steinberg, Thomas P Burris, Gavin Y Oudit, Tami A Martino
The circadian mechanism underlies daily rhythms in cardiovascular physiology and rhythm disruption is a major risk factor for heart disease and worse outcomes. However, the role of circadian rhythms is generally clinically unappreciated. Clock is a core component of the circadian mechanism and here we examine the role of Clock as a vital determinant of cardiac physiology and pathophysiology in aging. Clock(Δ19/Δ19) mice develop age-dependent increases in heart weight, hypertrophy, dilation, impaired contractility, and reduced myogenic responsiveness...
February 18, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28222291/circadian-rhythms-the-price-of-electric-light
#5
Jonathan S Emens
A new study demonstrates that modern electric lighting has caused the near-24-hour biological clock to be set to a later time and that humans physiologically respond to seasonal changes in day length under conditions of natural light exposure.
February 20, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28220104/systems-biology-derived-discoveries-of-intrinsic-clocks
#6
REVIEW
Arthur Millius, Hiroki R Ueda
A systems approach to studying biology uses a variety of mathematical, computational, and engineering tools to holistically understand and model properties of cells, tissues, and organisms. Building from early biochemical, genetic, and physiological studies, systems biology became established through the development of genome-wide methods, high-throughput procedures, modern computational processing power, and bioinformatics. Here, we highlight a variety of systems approaches to the study of biological rhythms that occur with a 24-h period-circadian rhythms...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28219785/transcriptional-alterations-induced-by-binary-mixtures-of-ethinylestradiol-and-norgestrel-during-the-early-development-of-zebrafish-danio-rerio
#7
Yan-Qiu Liang, Guo-Yong Huang, Jian-Liang Zhao, Wen-Jun Shi, Li-Xin Hu, Fei Tian, Shuang-Shuang Liu, Yu-Xia Jiang, Guang-Guo Ying
Synthetic estrogens and progestins are commonly used in human and veterinary medicine. After use, they reach aquatic environments via discharge of wastewaters from human and animals, thus posing potential risks to organisms. So far, very little is known about their combined effects in aquatic organisms. The aim of this study was to investigate the effects of binary mixtures of ethinylestradiol (EE2) and norgestrel (NGT) on embryonic zebrafish (Danio rerio) by measuring transcriptional alterations. Zebrafish embryos were exposed to EE2 and NGT alone or in combination at concentrations between 36 and 5513 ng L(-1) for 96 h post fertilization (hpf)...
February 17, 2017: Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP
https://www.readbyqxmd.com/read/28219731/time-place-learning-and-activity-profile-under-constant-light-and-constant-dark-in-zebrafish-danio-rerio
#8
Clarissa Ade Almeida Moura, Jéssica Polyana da Silva Lima, Vanessa Augusta Magalhães Silveira, Mário André Leocadio Miguel, Ana Carolina Luchiari
The ability to learn about the signs of variability in space and time is known as time place learning (TPL). To adjust their circadian rhythms, animals use stimuli that change regularly, such as the light-dark cycle, temperature, food availability or even social stimuli. Because light-dark cycle is the most important environmental temporal cue, we asked how a diurnal animal would perform TPL if this cue was removed. Zebrafish has been extensively studied in the chronobiology area due to it diurnal chronotype, thus, we studied the effects of constant light and constant dark on the time-place learning and activity profile in zebrafish...
February 17, 2017: Behavioural Processes
https://www.readbyqxmd.com/read/28219335/stress-responsive-pathways-and-small-rna-changes-distinguish-variable-developmental-phenotypes-caused-by-msh1-loss
#9
Mon-Ray Shao, Sunil Kumar Kenchanmane Raju, John D Laurie, Robersy Sanchez, Sally A Mackenzie
BACKGROUND: Proper regulation of nuclear-encoded, organelle-targeted genes is crucial for plastid and mitochondrial function. Among these genes, MutS Homolog 1 (MSH1) is notable for generating an assortment of mutant phenotypes with varying degrees of penetrance and pleiotropy. Stronger phenotypes have been connected to stress tolerance and epigenetic changes, and in Arabidopsis T-DNA mutants, two generations of homozygosity with the msh1 insertion are required before severe phenotypes begin to emerge...
February 20, 2017: BMC Plant Biology
https://www.readbyqxmd.com/read/28219319/biomarkers-in-alzheimer-s-disease-recent-update
#10
Sushil Sharma, Walter Lipincott
Alzheimer disease (AD) is an age-related neurodegenerative disorder, characterized by loss of memory and cognitive function. It is the common cause of dementia in elderly and is a global health concern as the population of people aged 85 and older, is growing alarmingly. Although pharmacotherapy for the treatment of AD has improved, lot of work remains to treat this devastating disease. AD pathology begins even before the onset of clinical symptoms. Because therapies could be more effective if implemented early in the disease progression, it is highly prudent to discover reliable biomarkers, to detect its exact pathophysiology during pre-symptomatic stage...
February 20, 2017: Current Alzheimer Research
https://www.readbyqxmd.com/read/28218891/blood-transcriptome-based-biomarkers-for-human-circadian-phase
#11
Emma E Laing, Carla S Möller-Levet, Norman Poh, Nayantara Santhi, Simon N Archer, Derk-Jan Dijk
Diagnosis and treatment of circadian rhythm sleep-wake disorders both require assessment of circadian phase of the brain's circadian pacemaker. The gold-standard univariate method is based on collection of a 24-hr time series of plasma melatonin, a suprachiasmatic nucleus-driven pineal hormone. We developed and validated a multivariate whole-blood mRNA-based predictor of melatonin phase which requires few samples. Transcriptome data were collected under normal, sleep-deprivation and abnormal sleep-timing conditions to assess robustness of the predictor...
February 20, 2017: ELife
https://www.readbyqxmd.com/read/28218824/decreased-home-cage-movement-and-oromotor-impairments-in-adult-fmr1-ko-mice
#12
Stephen J Bonasera, Tammy R Chaudoin, Evan H Goulding, Mateusz Mittek, Anna Dunaevsky
Fragile X syndrome (FXS) is a common inherited disorder that significantly impacts family and patient day-to-day living across the entire lifespan. The childhood and adolescent behavioral consequences of FXS are well-appreciated. However, there are significantly fewer studies (except those examining psychiatric comorbidities) assessing behavioral phenotypes seen in adults with FXS. Mice engineered with a genetic lesion of Fmr1 recapitulate important molecular and neuroanatomical characteristics of FXS, and provide a means to evaluate adult behavioral phenotypes associated with FXS...
February 20, 2017: Genes, Brain, and Behavior
https://www.readbyqxmd.com/read/28216658/timing-the-day-what-makes-bacterial-clocks-tick
#13
REVIEW
Carl Hirschie Johnson, Chi Zhao, Yao Xu, Tetsuya Mori
Chronobiological studies of prokaryotic organisms have generally lagged far behind the study of endogenous circadian clocks in eukaryotes, in which such systems are essentially ubiquitous. However, despite only being studied during the past 25 years, cyanobacteria have become important model organisms for the study of circadian rhythms and, presently, their timekeeping mechanism is the best understood of any system in terms of biochemistry, structural biology, biophysics and adaptive importance. Nevertheless, intrinsic daily rhythmicity among bacteria other than cyanobacteria is essentially unknown; some tantalizing information suggests widespread daily timekeeping among Eubacteria and Archaea through mechanisms that share common elements with the cyanobacterial clock but are distinct...
February 20, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28215254/epidemiology-of-sleep-and-sleep-disorders-in-the-netherlands
#14
Gerard A Kerkhof
OBJECTIVE: There is a surging public interest in The Netherlands concerning sleep, sleep disorders and associated health. For a proper perspective, it is necessary to have reliable information on the prevalence of sleep characteristics at the national level. This study set out to assess prevalence rates and key characteristics of sleep and sleep disorders in The Netherlands. METHODS: In 2012, a nationally representative sample of 2089 individuals, aged 18-70 years, responded to a set of 48 questions, including the Holland Sleep Disorders Questionnaire, a validated questionnaire based on the International Classification of Sleep Disorders...
February 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28215246/regional-gray-matter-changes-in-shift-workers-a-voxel-based-morphometry-study
#15
Jung Bin Kim, Ji Hyun Kim
OBJECTIVE: Previous neuroimaging studies have shown subtle structural changes of the brain in various sleep disorders, suggesting detrimental effects of disrupted sleep-wake cycle on brain structures. We aimed to identify structural changes in shift workers relative to day workers. We hypothesized that brain structures belonging to sleep-wake modulation may be altered in shift workers. METHODS: Nineteen male shift workers (median age, 21 years) and 19 male day workers (median age, 21 years) voluntarily participated in the current study...
February 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28215240/morningness-eveningness-correlates-with-sleep-time-quality-and-hygiene-in-secondary-school-students-a-multilevel-analysis
#16
Christian Vollmer, Konrad S Jankowski, Juan F Díaz-Morales, Heike Itzek-Greulich, Peter Wüst-Ackermann, Christoph Randler
At the onset of puberty, students shift their sleep to later hours, but school starts early. It is suggested that evening orientation and early school start times do not go well together. Therefore, the aim of this study was to investigate sleep problems in adolescence, and it was expected that the adolescents' eveningness orientation is associated with many sleep-related problems. Students of secondary education (n = 3201; mean = 13.8 ± 1.8 years) filled out a self-report questionnaire containing measures of morningness-eveningness, sleep time (midpoint of sleep, social "jetlag"), sleep length (on schooldays and on weekends), sleep quality, and sleep hygiene as well as questions on electronic screen media use...
February 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28215235/personality-differences-in-patients-with-delayed-sleep-wake-phase-disorder-and-non-24-h-sleep-wake-rhythm-disorder-relative-to-healthy-sleepers
#17
Gorica Micic, Nicole Lovato, Michael Gradisar, Leon C Lack
OBJECTIVE/BACKGROUND: Delayed sleep-wake phase disorder (DSWPD) is associated with a delayed timing of circadian rhythms, and this delay is suggested to be the basis of the disorder. However, this has been questioned due to frequent relapses following treatment based on this aetiology. Recent studies have emerged suggesting personality factors may contribute to sleep patterns in DSWPD. The aim of this study was to further investigate circadian and personality factors in DSWPD patients as well as patients with non-24-h sleep-wake rhythm disorder (N24SWD) relative to control sleepers...
February 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28214989/exposure-response-analyses-of-blood-pressure-and-heart-rate-changes-for-methylphenidate-in-healthy-adults
#18
Liang Li, Yaning Wang, Ramana S Uppoor, Mehul U Mehta, Tiffany Farchione, Mitchell V Mathis, Hao Zhu
The aim of the study was to evaluate the exposure-response (E-R) relationships of blood pressure (BP) and heart rate (HR) changes in healthy adults taking methylphenidate (MPH). Intensive time profiles of BP and HR from healthy adults in placebo and MPH treatment arms of seven clinical trials from the FDA internal database were utilized for this analysis. The analysis model contains a circadian component for placebo effect and an E-R component to describe drug effect. Internal validation was performed using goodness-of-fit plots and visual predictive check...
February 18, 2017: Journal of Pharmacokinetics and Pharmacodynamics
https://www.readbyqxmd.com/read/28213822/effect-of-lipopolysaccharide-on-circadian-clock-genes-per2-and-bmal1-in-mouse-ovary
#19
Takashi Shimizu, Kaya Watanabe, Nozomi Anayama, Koyomi Miyazaki
In mammals, circadian rhythms are associated with multiple physiological events. The aim of the present study was to examine the effect of lipopolysaccharide (LPS) on circadian systems in the ovary. Immature female mice were received an intra-peritoneal injection of equine chorionic gonadotropin (eCG) and LPS. Total RNA was collected from the ovary at 6-h intervals throughout a 48 h of experimental period. The expression of the circadian genes period 2 (Per2) and brain and muscle ARNT-like 1 (Bmal1) such as circadian genes was measured by quantitative PCR...
February 17, 2017: Journal of Physiological Sciences: JPS
https://www.readbyqxmd.com/read/28211649/insufficient-sleep-in-adolescents-causes-and-consequences
#20
Judith A Owens, Miriam R Weiss
Insufficient sleep poses an important and complicated set of health risks in the adolescent population. Not only is deficient sleep (defined as both sleep duration inadequate to meet sleep needs and sleep timing misaligned with the body's circadian rhythms) at epidemic levels in this population, but the contributing factors are both complex and numerous and there are a myriad of negative physical and mental health, safety and performance consequences. Causes of inadequate sleep identified in this population include internal biological processes such as the normal shift (delay) in circadian rhythm that occurs in association with puberty and a developmentally-based slowing of the "sleep drive", and external factors including extracurricular activities, excessive homework load, evening use of electronic media, caffeine intake and early school start times...
February 17, 2017: Minerva Pediatrica
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