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Phase angle circadian

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https://www.readbyqxmd.com/read/30315193/integration-of-color-and-intensity-increases-time-signal-stability-for-the-human-circadian-system-when-sunlight-is-obscured-by-clouds
#1
T Woelders, E J Wams, M C M Gordijn, D G M Beersma, R A Hut
The mammalian circadian system encodes both absolute levels of light intensity and color to phase-lock (entrain) its rhythm to the 24-h solar cycle. The evolutionary benefits of circadian color-coding over intensity-coding per se are yet far from understood. A detailed characterization of sunlight is crucial in understanding how and why circadian photoreception integrates color and intensity information. To this end, we continuously measured 100 days of sunlight spectra over the course of a year. Our analyses suggest that circadian color-coding may have evolved to cope with cloud-induced variation in light intensity...
October 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30175684/the-phosphorylation-of-creb-at-serine-133-is-a-key-event-for-circadian-clock-timing-and-entrainment-in-the-suprachiasmatic-nucleus
#2
Kelin L Wheaton, Katelin F Hansen, Sydney Aten, Kyle A Sullivan, Hyojung Yoon, Kari R Hoyt, Karl Obrietan
Within the suprachiasmatic nucleus (SCN)-the locus of the master circadian clock- transcriptional regulation via the CREB/CRE pathway is implicated in the functioning of the molecular clock timing process, and is a key conduit through which photic input entrains the oscillator. One event driving CRE-mediated transcription is the phosphorylation of CREB at serine 133 (Ser133 ). Indeed, numerous reporter gene assays have shown that an alanine point mutation in Ser133 reduces CREB-mediated transcription. Here, we sought to examine the contribution of Ser133 phosphorylation to the functional role of CREB in SCN clock physiology in vivo...
September 3, 2018: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/29865270/impaired-photic-entrainment-of-spontaneous-locomotor-activity-in-mice-overexpressing-human-mutant-%C3%AE-synuclein
#3
Martina Pfeffer, Zuzana Zimmermann, Suzana Gispert, Georg Auburger, Horst-Werner Korf, Charlotte von Gall
Parkinson's disease (PD) is characterized by distinct motor and non-motor symptoms. Sleep disorders are the most frequent and challenging non-motor symptoms in PD patients, and there is growing evidence that they are a consequence of disruptions within the circadian system. PD is characterized by a progressive degeneration of the dorsal vagal nucleus and midbrain dopaminergic neurons together with an imbalance of many other neurotransmitters. Mutations in α-synuclein (SNCA), a protein modulating SNARE complex-dependent neurotransmission, trigger dominantly inherited PD variants and sporadic cases of PD...
June 3, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29842813/changes-in-phase-angle-under-light-dark-cycles-influenced-by-nonphotic-stimulation
#4
Daniel Janik, Justin Frey
Most work looking at nonphotic effects on circadian rhythms is conducted when animals are held under freerunning conditions, usually constant darkness. However, for nonphotic effects to be functionally significant, they should be demonstrable under conditions in which most animals live, i.e., a 24-hr light-dark cycle (LD). Syrian hamsters held in LD 6:18 were administered nonphotic stimulation in the form of a 3-hr confinement to a novel wheel starting about 6 hr before the start of their normal nightly activity bout...
May 29, 2018: Chronobiology International
https://www.readbyqxmd.com/read/29727473/can-circadian-dysregulation-exacerbate-migraines
#5
Jason C Ong, Hannah L Taylor, Margaret Park, Helen J Burgess, Rina S Fox, Sarah Snyder, Jeanetta C Rains, Colin A Espie, James K Wyatt
OBJECTIVE: This observational pilot study examined objective circadian phase and sleep timing in chronic migraine (CM) and healthy controls (HC) and the impact of circadian factors on migraine frequency and severity. BACKGROUND: Sleep disturbance has been identified as a risk factor in the development and maintenance of CM but the biological mechanisms linking sleep and migraine remain largely theoretical. METHODS: Twenty women with CM and 20 age-matched HC completed a protocol that included a 7 day sleep assessment at home using wrist actigraphy followed by a circadian phase assessment using salivary melatonin...
July 2018: Headache
https://www.readbyqxmd.com/read/29609703/diagnostic-and-treatment-challenges-of-sighted-non-24-hour-sleep-wake-disorder
#6
Roneil G Malkani, Sabra M Abbott, Kathryn J Reid, Phyllis C Zee
STUDY OBJECTIVES: To report the diagnostic and treatment challenges of sighted non-24-hour sleep-wake disorder (N24SWD). METHODS: We report a series of seven sighted patients with N24SWD clinically evaluated by history and sleep diaries, and when available wrist actigraphy and salivary melatonin levels, and treated with timed melatonin and bright light therapy. RESULTS: Most patients had a history of a delayed sleep-wake pattern prior to developing N24SWD...
April 15, 2018: Journal of Clinical Sleep Medicine: JCSM: Official Publication of the American Academy of Sleep Medicine
https://www.readbyqxmd.com/read/29372816/mechanisms-of-social-synchrony-between-circadian-activity-rhythms-in-cohabiting-marmosets
#7
Zoélia Camila Moura Bessa, Paula Rocha De Melo, Bruno S B Gonçalves, Carolina V M De Azevedo
In marmosets, social synchrony between circadian profiles of activity is stronger in animals that cohabit in a family. The activity of three breeding pairs was recorded by actiwatches to investigate the mechanisms involved in the synchrony between the circadian activity profiles during cohabitation in marmoset reproductive pairs. The dyads were submitted to LD 12:12 (21 days) and LL: 1) cohabitation (24 days), 2) removal of the cage mate (20 days), 3) reintroduction of the mate into the cage of the 1st situation (30 days) and 4) removal of the cage mate (7 days)...
May 2018: Chronobiology International
https://www.readbyqxmd.com/read/29163208/circadian-alterations-in-a-murine-model-of-hypothalamic-glioma
#8
José M Duhart, Lucila Brocardo, Carlos S Caldart, Luciano Marpegan, Diego A Golombek
The mammalian circadian system is controlled by a central oscillator located in the suprachiasmatic nuclei (SCN) of the hypothalamus, in which glia appears to play a prominent role. Gliomas originate from glial cells and are the primary brain tumors with the highest incidence and mortality. Optic pathway/hypothalamic gliomas account for 4-7% of all pediatric intracranial tumors. Given the anatomical location, which compromises both the circadian pacemaker and its photic input pathway, we decided to study whether the presence of gliomas in the hypothalamic region could alter circadian behavioral outputs...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/29148844/circadian-phase-circadian-period-and-chronotype-are-reproducible-over-months
#9
Thomas Kantermann, Charmane I Eastman
The timing of the circadian clock, circadian period and chronotype varies among individuals. To date, not much is known about how these parameters vary over time in an individual. We performed an analysis of the following five common circadian clock and chronotype measures: 1) the dim light melatonin onset (DLMO, a measure of circadian phase), 2) phase angle of entrainment (the phase the circadian clock assumes within the 24-h day, measured here as the interval between DLMO and bedtime/dark onset), 3) free-running circadian period (tau) from an ultradian forced desynchrony protocol (tau influences circadian phase and phase angle of entrainment), 4) mid-sleep on work-free days (MSF from the Munich ChronoType Questionnaire; MCTQ) and 5) the score from the Morningness-Eveningness Questionnaire (MEQ)...
February 2018: Chronobiology International
https://www.readbyqxmd.com/read/29066952/the-sleep-wake-cycle-in-the-nicotinic-alpha-9-acetylcholine-receptor-subunit-knock-out-mice
#10
Natalia Madrid-López, Jorge Estrada, Javier Díaz, Alejandro Bassi, Paul H Délano, Adrián Ocampo-Garcés
There is a neural matrix controlling the sleep-wake cycle (SWC) embedded within high ranking integrative mechanisms in the central nervous system. Nicotinic alpha-9 acetylcholine receptor subunit (alpha-9 nAChR) participate in physiological processes occurring in sensory, endocrine and immune systems. There is a relationship between the SWC architecture, body homeostasis and sensory afferents so that disruption of afferent signaling is expected to affect the temporal organization of sleep and wake states. The analysis of the SWC of 9 nAChR knock-out animals may help to reveal the contribution of alpha-9 nAChR to sleep chronobiological determinants...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/29044737/chronic-bmy7378-treatment-alters-behavioral-circadian-rhythms
#11
Jhenkruthi Vijaya Shankara, Angélique Orr, Richelle Mychasiuk, Michael C Antle
The mammalian circadian clock is synchronized to the day : night cycle by light. Serotonin modulates the circadian effects of light, with agonists inhibiting response to light and antagonists enhancing responses to light. A special class of serotonergic compounds, the mixed 5-HT1A agonist/antagonists, potentiates light-induced phase advances by up to 400% when administered acutely. In this study, we examine the effects of one of these mixed 5-HT1A agonist/antagonists, BMY7378, when administered chronically...
December 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/29029340/circadian-phase-and-phase-angle-disorders-in-primary-insomnia
#12
Erin E Flynn-Evans, Julia A Shekleton, Belinda Miller, Lawrence J Epstein, Douglas Kirsch, Lauren A Brogna, Liza M Burke, Erin Bremer, Jade M Murray, Philip Gehrman, Shantha M W Rajaratnam, Steven W Lockley
Objectives: We aimed to identify the prevalence of circadian phase and phase angle abnormalities in patients with insomnia. Methods: We conducted a cross-sectional, multicenter study at three sleep laboratories in the United States and Australia. Patients with insomnia and healthy control participants completed a sleep log for 7 days. Circadian phase was assessed from salivary dim light melatonin onset (DLMO) time during a 12-hour laboratory visit. Results: Seventy-nine patients meeting the Research Diagnostic Criteria for Primary, Psychophysiological, Paradoxical, and/or Idiopathic Childhood Insomnia (46 females, 35...
December 1, 2017: Sleep
https://www.readbyqxmd.com/read/28313043/-diurnal-rythm-of-locomotor-activity-in-admetus-pumilio-c-koch-arach-amblypygi-from-the-neotropical-rain-forest-ii
#13
L Beck
The locomotor activity of the exclusively dark-active species Admetus pumilio shows a bigeminal type of diurnal rhythm, modified by an interposed third peak of activity. In accordance with Aschoff's rule, the period length depends on light intensity and is shortened in DD. The phase-angle difference must be determined separately for each form of activity. The first movements at the resting place ("awakening") and departure from it are the most readily identifiable forms of activity. Awakening takes place earlier and earlier with decreasing light intensity, thus diverging from departure more and more...
March 1972: Oecologia
https://www.readbyqxmd.com/read/28285255/relationships-between-circadian-measures-depression-and-response-to-antidepressant-treatment-a-preliminary-investigation
#14
RANDOMIZED CONTROLLED TRIAL
Leslie M Swanson, Helen J Burgess, Edward D Huntley, Holli Bertram, Ann Mooney, Jennifer Zollars, Richard Dopp, Robert Hoffmann, Roseanne Armitage, J Todd Arnedt
Few studies have examined relationships between circadian rhythms and unipolar major depressive disorder. Further, no study to date has examined circadian markers as predictors of response to depression treatment. In the present study, we examined associations between circadian timing and its alignment with sleep and depression severity in 30 adults with major depressive disorder who completed a randomized controlled trial of two weeks of time in bed (TIB) restriction administered adjunctive to fluoxetine, with a focus on sex differences...
June 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28087763/circadian-kinetics-of-cell-cycle-progression-in-adult-neurogenic-niches-of-a-diurnal-vertebrate
#15
Veronica Akle, Alexander J Stankiewicz, Vasili Kharchenko, Lili Yu, Peter V Kharchenko, Irina V Zhdanova
The circadian system may regulate adult neurogenesis via intracellular molecular clock mechanisms or by modifying the environment of neurogenic niches, with daily variation in growth factors or nutrients depending on the animal's diurnal or nocturnal lifestyle. In a diurnal vertebrate, zebrafish, we studied circadian distribution of immunohistochemical markers of the cell division cycle (CDC) in 5 of the 16 neurogenic niches of adult brain, the dorsal telencephalon, habenula, preoptic area, hypothalamus, and cerebellum...
February 15, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27812851/pineal-volume-and-evening-melatonin-in-young-people-with-affective-disorders
#16
Joanne S Carpenter, Amy C Abelmann, Sean N Hatton, Rébecca Robillard, Daniel F Hermens, Maxwell R Bennett, Jim Lagopoulos, Ian B Hickie
Affective disorders in young people have been associated with disruptions in circadian rhythms, including abnormalities in secretion of the pineal hormone melatonin. Previous research reports relationships between pineal gland volumes, melatonin secretion, and sleep-wake cycles, but the relationship between these factors has not been explored in affective disorders. This study aimed to characterize these factors and explore associations with mood symptoms and functioning in a sample of young people with affective disorders...
December 2017: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/27795550/circadian-timing-and-alignment-in-healthy-adults-associations-with-bmi-body-fat-caloric-intake-and-physical-activity
#17
K G Baron, K J Reid, T Kim, L Van Horn, H Attarian, L Wolfe, J Siddique, G Santostasi, P C Zee
INTRODUCTION: Disruption of circadian rhythms is one of the proposed mechanisms linking late sleep timing to obesity risk but few studies have evaluated biological markers outside of the laboratory. The goal of this study was to determine the relationship between the timing and alignment of melatonin and sleep onset (phase angle) with body mass index (BMI), body fat and obesity-related behaviors. We hypothesized that circadian alignment (relationship of melatonin to sleep timing) rather than circadian (melatonin) timing would be associated with higher BMI, body fat, dietary intake and lower physical activity...
February 2017: International Journal of Obesity: Journal of the International Association for the Study of Obesity
https://www.readbyqxmd.com/read/27090227/variability-of-behavioral-chronotypes-of-16-mammalian-species-under-controlled-conditions
#18
Roberto Refinetti, Thomas Wassmer, Priyoneel Basu, Rajeev Cherukalady, Varun Kumar Pandey, Muniyandi Singaravel, Claudia Giannetto, Giuseppe Piccione
Human chronotypes (differences in preference for early or late rising each day) have been extensively studied in recent years, but no attempt has been made to compare human chronotypes with the chronotypes of other animal species. We evaluated behavioral chronotypes in 16 mammalian species along a body size gradient of five orders of magnitude (from mice to cattle). Individuals of all species were studied under a 12L:12D photoperiod in a thermoneutral environment with food and water available at all times. Rhythms of locomotor activity were analyzed for onset time, acrophase, and robustness...
July 1, 2016: Physiology & Behavior
https://www.readbyqxmd.com/read/26632431/age-associated-advance-of-sleep-times-relative-to-the-circadian-phase-of-alertness-sleepiness-rhythm-can-it-be-explained-by-changes-in-ratios-between-strengths-of-the-underlying-oscillatory-processes
#19
Arcady A Putilov
The aging process is often associated with more or less prominent shifts of the entrained phases of behavioral and physiological rhythms at earlier clock hours, but the oscillatory mechanisms underlying these shifts have to be determined. The analysis of self-reports on home sleep times and self-scorings of sleepiness provided by 130 participants of sleep deprivation experiments revealed the difference between intro-individual (age-related) and inter-individual (gender- and chronotype-related) variation in phase angle between sleep timing and timing of nocturnal rise of sleepiness...
2016: Current Aging Science
https://www.readbyqxmd.com/read/26079115/chronotype-in-patients-with-epilepsy-a-controlled-study-in-60-subjects-with-late-onset-focal-epilepsy
#20
Raffaele Manni, Riccardo Cremascoli, Roberto De Icco, Michele Terzaghi
Studies based on self-administered questionnaires indicate that most patients with epilepsy are morning-oriented. We aimed to investigate chronotype in patients with epilepsy with late-onset focal epilepsy by combining subjective data with dim light melatonin onset (DLMO) as an objective marker of the circadian phase. Sixty adult patients (mean age 46.5±13.8; 27 males) with late-onset focal epilepsy under pharmacological treatment were prospectively studied. Subjective chronotype was determined using the Morningness-Eveningness Questionnaire (MEQ) and circadian phase through analysis of salivary melatonin secretion, considering 3pg/ml as the dim light melatonin onset (DLMO) threshold...
September 2015: Epilepsy & Behavior: E&B
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