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Journal of Biological Rhythms

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https://www.readbyqxmd.com/read/28088873/developmental-changes-in-ultradian-sleep-cycles-across-early-childhood
#1
Sean Lopp, William Navidi, Peter Achermann, Monique LeBourgeois, Cecilia Diniz Behn
Nocturnal human sleep is composed of cycles between rapid eye movement (REM) sleep and non-REM (NREM) sleep. In adults, the structure of ultradian cycles between NREM and REM sleep is well characterized; however, less is known about the developmental trajectories of ultradian sleep cycles across early childhood. Cross-sectional studies indicate that the rapid ultradian cycling of active-quiet sleep in infancy shifts to a more adult-like pattern of NREM-REM sleep cycling by the school-age years, yet longitudinal studies elucidating the details of this transition are scarce...
January 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28013579/a-rodent-model-of-night-shift-work-induces-short-term-and-enduring-sleep-and-electroencephalographic-disturbances
#2
Janne Grønli, Peter Meerlo, Torhild T Pedersen, Ståle Pallesen, Silje Skrede, Andrea R Marti, Jonathan P Wisor, Robert Murison, Tone E G Henriksen, Michael J Rempe, Jelena Mrdalj
Millions of people worldwide are working at times that overlap with the normal time for sleep. Sleep problems related to the work schedule may mediate the well-established relationship between shift work and increased risk for disease, occupational errors and accidents. Yet, our understanding of causality and the underlying mechanisms that explain this relationship is limited. We aimed to assess the consequences of night-shift work for sleep and to examine whether night-shift work-induced sleep disturbances may yield electrophysiological markers of impaired maintenance of the waking brain state...
December 1, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28006966/social-jetlag-among-night-workers-is-negatively-associated-with-the-frequency-of-moderate-or-vigorous-physical-activity-and-with-energy-expenditure-related-to-physical-activity
#3
Mariana Silva Alves, Raphael Zardini Andrade, Graciele Cristina Silva, Maria Carliana Mota, Sabrina Gonçalves Resende, Kely Raspante Teixeira, Bruna Fernandes Gonçalves, Cibele Aparecida Crispim
This cross-sectional study analyzed the association between physical activity (PA) and social jetlag (SJL) among shift workers. We evaluated 423 employees, aged between 18 and 60 years, who worked in a poultry-processing company in Brazil. Physical activity levels (PAL) were determined by the short form of the International Physical Activity Questionnaire (IPAQ-SF). SJL was calculated as the absolute difference between the time of mid-sleep on work and free days. The percentage of workers insufficiently active was high on all shifts, with no significant differences between the 3 shifts...
December 1, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27920227/geographic-variation-of-plant-circadian-clock-function-in-natural-and-agricultural-settings
#4
Kathleen Greenham, Ping Lou, Joshua R Puzey, Ganesh Kumar, Cindy Arnevik, Hany Farid, John H Willis, C Robertson McClung
The increasing demand for improved agricultural production will require more efficient breeding for traits that maintain yield under heterogeneous environments. The internal circadian oscillator is essential for perceiving and coordinating environmental cues such as day length, temperature, and abiotic stress responses within physiological processes. To investigate the contribution of the circadian clock to local adaptability, we have analyzed circadian period by leaf movement in natural populations of Mimulus guttatus and domesticated cultivars of Glycine max...
December 1, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28112045/in-depth-characterization-of-firefly-luciferase-as-a-reporter-of-circadian-gene-expression-in-mammalian-cells
#5
Kevin A Feeney, Marrit Putker, Marco Brancaccio, John S O'Neill
Firefly luciferase (Fluc) is frequently used to report circadian gene expression rhythms in mammalian cells and tissues. During longitudinal assays it is generally assumed that enzymatic substrates are in saturating excess, such that total bioluminescence is directly proportional to Fluc protein level. To test this assumption, we compared the enzyme kinetics of purified luciferase with its activity in mammalian cells. We found that Fluc activity in solution has a lower Michaelis constant (Km) for luciferin, lower temperature dependence, and lower catalytic half-life than Fluc in cells...
December 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28112044/andreas-horlitz-artist
#6
Anna Wirz-Justice
No abstract text is available yet for this article.
December 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27836939/statistics-for-sleep-and-biological-rhythms-research-longitudinal-analysis-of-biological-rhythms-data
#7
Elizabeth B Klerman, Wei Wang, Andrew J K Phillips, Matt T Bianchi
This article is part of a Journal of Biological Rhythms series exploring analysis and statistical topics relevant to researchers in biological rhythms and sleep research. The goal is to provide an overview of the most common issues that arise in the analysis and interpretation of data in these fields. In this article, we address issues related to the collection of multiple data points from the same organism or system at different times, since such longitudinal data collection is fundamental to the assessment of biological rhythms...
October 24, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27836938/statistics-for-sleep-and-biological-rhythms-research-from-distributions-and-displays-to-correlation-and-causation
#8
Matt T Bianchi, Andrew J K Phillips, Wei Wang, Elizabeth B Klerman
The Journal of Biological Rhythms will be publishing articles exploring analysis and statistical topics relevant to researchers in biological rhythms and sleep research. The goal is to provide an overview of the most common issues that arise in the analysis and interpretation of data in these fields. By using case examples and highlighting the pearls and pitfalls of statistical inference, the authors will identify and explain ways in which experimental scientists can avoid common analytical and statistical mistakes and use appropriate analytical and statistical methods in their research...
October 24, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27754956/entrainment-maps-a-new-tool-for-understanding-properties-of-circadian-oscillator-models
#9
Casey O Diekman, Amitabha Bose
Circadian oscillators found across a variety of species are subject to periodic external light-dark forcing. Entrainment to light-dark cycles enables the circadian system to align biological functions with appropriate times of day or night. Phase response curves (PRCs) have been used for decades to gain valuable insights into entrainment; however, PRCs may not accurately describe entrainment to photoperiods with substantial amounts of both light and dark due to their reliance on a single limit cycle attractor...
October 17, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27708112/unexpected-geographic-variability-of-the-free-running-period-in-the-linden-bug-pyrrhocoris-apterus
#10
Lenka Pivarciova, Hanka Vaneckova, Jan Provaznik, Bulah Chia-Hsiang Wu, Martin Pivarci, Olga Peckova, Olga Bazalova, Stepan Cada, Petr Kment, Joanna Kotwica-Rolinska, David Dolezel
Circadian clocks keep organisms in synchrony with external day-night cycles. The free running period (FRP) of the clock, however, is usually only close to-not exactly-24 h. Here, we explored the geographical variation in the FRP of the linden bug, Pyrrhocoris apterus, in 59 field-lines originating from a wide variety of localities representing geographically different environments. We have identified a remarkable range in the FRPs between field-lines, with the fastest clock at ~21 h and the slowest close to 28 h, a range comparable to the collections of clock mutants in model organisms...
October 5, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27702781/differential-phasing-between-circadian-clocks-in-the-brain-and-peripheral-organs-in-humans
#11
Jacob J Hughey, Atul J Butte
The daily timing of mammalian physiology is coordinated by circadian clocks throughout the body. Although measurements of clock gene expression indicate that these clocks in mice are normally in phase with each other, the situation in humans remains unclear. We used publicly available data from five studies, comprising over 1000 samples, to compare the phasing of circadian gene expression in human brain and human blood. Surprisingly, after controlling for age, clock gene expression in brain was phase-delayed by ~8...
October 4, 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27634928/behavioral-timing-without-clockwork-photoperiod-dependent-trade-off-between-predation-hazard-and-energy-balance-in-an-arctic-ungulate
#12
Nicholas J C Tyler, Pablo Gregorini, Mads C Forchhammer, Karl-Arne Stokkan, Bob E H van Oort, David G Hazlerigg
Occurrence of 24-h rhythms in species apparently lacking functional molecular clockwork indicates that strong circadian mechanisms are not essential prerequisites of robust timing, and that rhythmical patterns may arise instead as passive responses to periodically changing environmental stimuli. Thus, in a new synthesis of grazing in a ruminant (MINDY), crepuscular peaks of activity emerge from interactions between internal and external stimuli that influence motivation to feed, and the influence of the light/dark cycle is mediated through the effect of low nocturnal levels of food intake on gastric function...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27558096/circadian-clocks-in-articular-cartilage-and-bone-a-compass-in-the-sea-of-matrices
#13
REVIEW
Nan Yang, Qing-Jun Meng
Temporally coordinated resorption and synthesis is the key to maintaining healthy bones. Articular cartilage is a highly specialized connective tissue within the joints that lines the surface of a long bone. Emerging evidence has suggested a critical role of the circadian system in controlling cartilage and bone biology. Articular cartilage is sparsely populated with chondrocytes, surrounded by abundant extracellular matrices that are synthesized and maintained solely by chondrocytes. Once damaged, the articular cartilage tissue has poor capacity for endogenous repair, leaving the joints prone to osteoarthritis, an age-related painful condition that affects millions of individuals worldwide...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27474192/daytime-exposure-to-short-and-medium-wavelength-light-did-not-improve-alertness-and-neurobehavioral-performance
#14
Ahuva Y Segal, Tracey L Sletten, Erin E Flynn-Evans, Steven W Lockley, Shantha M W Rajaratnam
While previous studies have demonstrated short-wavelength sensitivity to the acute alerting effects of light during the biological night, fewer studies have assessed the alerting effect of light during the daytime. This study assessed the wavelength-dependent sensitivity of the acute alerting effects of daytime light exposure following chronic sleep restriction in 60 young adults (29 men, 31 women; 22.5 ± 3.1 mean ± SD years). Participants were restricted to 5 h time in bed the night before laboratory admission and 3 h time in bed in the laboratory, aligned by wake time...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27466352/seasonal-time-keeping-in-a-long-distance-migrating-shorebird
#15
Julia Karagicheva, Eldar Rakhimberdiev, Anne Dekinga, Maarten Brugge, Anita Koolhaas, Job Ten Horn, Theunis Piersma
Because of the complications in achieving the necessary long-term observations and experiments, the nature and adaptive value of seasonal time-keeping mechanisms in long-lived organisms remain understudied. Here we present the results of a 20-year-long study of the repeated seasonal changes in body mass, plumage state, and primary molt of 45 captive red knots Calidris canutus islandica, a High Arctic breeding shorebird that spends the nonbreeding season in temperate coastal areas. Birds kept outdoors and experiencing the natural photoperiod of the nonbreeding area maintained sequences of life-cycle stages, roughly following the timing in nature...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27449477/pineal-gland-volume-assessed-by-mri-and-its-correlation-with-6-sulfatoxymelatonin-levels-among-older-men
#16
Lara G Sigurdardottir, Sarah C Markt, Sigurdur Sigurdsson, Thor Aspelund, Katja Fall, Eva Schernhammer, Jennifer R Rider, Lenore Launer, Tamara Harris, Meir J Stampfer, Vilmundur Gudnason, Charles A Czeisler, Steven W Lockley, Unnur A Valdimarsdottir, Lorelei A Mucci
The pineal gland produces the hormone melatonin, and its volume may influence melatonin levels. We describe an innovative method for estimating pineal volume in humans and present the association of pineal parenchyma volume with levels of the primary melatonin metabolite, 6-sulfatoxymelatonin. We selected a random sample of 122 older Icelandic men nested within the AGES-Reykjavik cohort and measured their total pineal volume, their parenchyma volume, and the extent of calcification and cysts. For volume estimations we used manual segmentation of magnetic resonance images in the axial plane with simultaneous side-by-side view of the sagittal and coronal plane...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27449476/short-blue-light-pulses-30-min-in-the-morning-support-a-sleep-advancing-protocol-in-a-home-setting
#17
Moniek Geerdink, Thijs J Walbeek, Domien G M Beersma, Vanja Hommes, Marijke C M Gordijn
Many people in our modern civilized society sleep later on free days compared to work days. This discrepancy in sleep timing will lead to so-called 'social jetlag' on work days with negative consequences for performance and health. Light therapy in the morning is often proposed as the most effective method to advance the circadian rhythm and sleep phase. However, most studies focus on direct effects on the circadian system and not on posttreatment effects on sleep phase and sleep integrity. In this placebo-controlled home study we investigated if blue light, rather than amber light therapy, can phase shift the sleep phase along with the circadian rhythm with preservation of sleep integrity and performance...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27432117/genetic-and-environmental-models-of-circadian-disruption-link-src-2-function-to-hepatic-pathology
#18
Tiffany Fleet, Erin Stashi, Bokai Zhu, Kimal Rajapakshe, Kathrina L Marcelo, Nicole M Kettner, Blythe K Gorman, Cristian Coarfa, Loning Fu, Bert W O'Malley, Brian York
Circadian rhythmicity is a fundamental process that synchronizes behavioral cues with metabolic homeostasis. Disruption of daily cycles due to jet lag or shift work results in severe physiological consequences including advanced aging, metabolic syndrome, and even cancer. Our understanding of the molecular clock, which is regulated by intricate positive feedforward and negative feedback loops, has expanded to include an important metabolic transcriptional coregulator, Steroid Receptor Coactivator-2 (SRC-2), that regulates both the central clock of the suprachiasmatic nucleus (SCN) and peripheral clocks including the liver...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27432116/sleep-propensity-under-forced-desynchrony-in-a-model-of-arousal-state-dynamics
#19
Svetlana Postnova, Steven W Lockley, Peter A Robinson
An improvement to our current quantitative model of arousal state dynamics is presented that more accurately predicts sleep propensity as measured with sleep dynamics depending on circadian phase and prior wakefulness. A nonlinear relationship between the circadian variables within the dynamic circadian oscillator model is introduced to account for the skewed shape of the circadian rhythm of alertness that peaks just prior to the onset of the biological night (the "wake maintenance zone") and has a minimum toward the end of the biological night...
October 2016: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/27269519/the-timed-depolarization-of-morning-and-evening-oscillators-phase-shifts-the-circadian-clock-of-drosophila
#20
Saskia Eck, Charlotte Helfrich-Förster, Dirk Rieger
Phase response curves (PRCs) for light or temperature stimuli have been shown to be most valuable in understanding how circadian clocks are entrained to daily environmental cycles. Nowadays, PRC experiments in which clock neurons are manipulated in a temporally restricted manner by thermogenetic or optogenetic tools are also useful to comprehend clock network properties. Here, we temporally depolarized specific clock neurons of Drosophila melanogaster by activating temperature-sensitive dTrpA1 channels to unravel their role in phase shifting the flies' activity rhythm...
October 2016: Journal of Biological Rhythms
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