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Circadian rhythm

Andreas Arendt, El-Sayed Baz, Monika Stengl
The circadian pacemaker of the Madeira cockroach Rhyparobia (Leucophaea) maderae is located in the accessory medulla (AME). Ipsi- and contralateral histaminergic compound eyes are required for photic entrainment. Light pulses delayed locomotor activity rhythms during the early night and advanced during the late night. Thus, different neuronal pathways might relay either light-dependent delays or advances to the clock. Injections of neuroactive substances combined with running-wheel assays suggested that GABA, PDF, myoinhibitory peptides (MIPs), and orcokinins (ORCs) are part of both entrainment pathways, while allatotropin (AT) only delayed locomotor rhythms at the early night...
October 20, 2016: Journal of Comparative Neurology
Víctor Resco de Dios, Arthur Gessler, Juan Pedro Ferrio, Josu G Alday, Michael Bahn, Jorge Del Castillo, Sébastien Devidal, Sonia García-Muñoz, Zachary Kayler, Damien Landais, Paula Martín-Gómez, Alexandru Milcu, Clément Piel, Karin Pirhofer-Walzl, Olivier Ravel, Serajis Salekin, David T Tissue, Mark G Tjoelker, Jordi Voltas, Jacques Roy
BACKGROUND: Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO2 and H2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy gas exchange at the Montpellier European Ecotron...
October 20, 2016: GigaScience
Gregory D M Potter, Debra J Skene, Josephine Arendt, Janet E Cade, Peter J Grant, Laura J Hardie
Circadian (∼ 24 hour) timing systems pervade all kingdoms of life, and temporally optimize behaviour and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behaviour and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these too are increasingly subject to disruption...
October 20, 2016: Endocrine Reviews
Rüdiger Hardeland
Dynamic aspects of melatonin's actions merit increasing future attention. This concerns particularly entirely different effects in senescent, weakened oscillators and in dysregulated oscillators of cancer cells that may be epigenetically blocked. This is especially obvious in the case of sirtuin 1 (SIRT1) which is upregulated by melatonin in aged tissues, but strongly downregulated in several cancer cells. These findings are not at all controversial, but are explained on the basis of divergent changes in weakened and dysregulated oscillators...
October 20, 2016: Journal of Pineal Research
Dirk Jan Stenvers, Rick van Dorp, Ewout Foppen, Jorge Mendoza, Anne-Loes Opperhuizen, Eric Fliers, Peter H Bisschop, Johanna H Meijer, Andries Kalsbeek, Tom Deboer
Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12 h light (150-200lux):12 h dark (LD) schedule or a 12 h light (150-200 lux):12 h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily rhythms of REM and NREM sleep, with a further decrease over the following days...
October 20, 2016: Scientific Reports
Joseph F O'Grady, Laura S Hoelters, Martin T Swain, David C Wilcockson
BACKGROUND: Talitrus saltator is an amphipod crustacean that inhabits the supralittoral zone on sandy beaches in the Northeast Atlantic and Mediterranean. T. saltator exhibits endogenous locomotor activity rhythms and time-compensated sun and moon orientation, both of which necessitate at least one chronometric mechanism. Whilst their behaviour is well studied, currently there are no descriptions of the underlying molecular components of a biological clock in this animal, and very few in other crustacean species...
2016: PeerJ
Aurore Woller, Hélène Duez, Bart Staels, Marc Lefranc
To maintain energy homeostasis despite variable energy supply and consumption along the diurnal cycle, the liver relies on a circadian clock synchronized to food timing. Perturbed feeding and fasting cycles have been associated with clock disruption and metabolic diseases; however, the mechanisms are unclear. To address this question, we have constructed a mathematical model of the mammalian circadian clock, incorporating the metabolic sensors SIRT1 and AMPK. The clock response to various temporal patterns of AMPK activation was simulated numerically, mimicking the effects of a normal diet, fasting, and a high-fat diet...
October 18, 2016: Cell Reports
Alberto Ugolini, Laura S Hoelters, Alice Ciofini, Vittorio Pasquali, David C Wilcockson
Animals that use astronomical cues to orientate must make continuous adjustment to account for temporal changes in azimuth caused by Earth's rotation. For example, the Monarch butterfly possesses a time-compensated sun compass dependent upon a circadian clock in the antennae. The amphipod Talitrus saltator possesses both a sun compass and a moon compass. We reasoned that the time-compensated compass mechanism that enables solar orientation of T. saltator is located in the antennae, as is the case for Monarch butterflies...
October 19, 2016: Scientific Reports
Jan Hansen, Silvie Timmers, Esther Moonen-Kornips, Helene Duez, Bart Staels, Matthijs K C Hesselink, Patrick Schrauwen
Cell and animal studies have demonstrated that circadian rhythm is governed by autonomous rhythmicity of clock genes. Although disturbances in circadian rhythm have been implicated in metabolic disease development, it remains unknown whether muscle circadian rhythm is altered in human models of type 2 diabetes. Here we used human primary myotubes (HPM) to investigate if rhythmicity of clock- and metabolic gene expression is altered in donors with obesity or type 2 diabetes compared to metabolically healthy donors...
October 19, 2016: Scientific Reports
Eunjoo Cho, Euna Lee, Eun Young Kim
The circadian clock system enables organisms to anticipate the rhythmic environmental changes and to manifest behavior and physiology at advantageous times of day. Transcriptional/translational feedback loop (TTFL) is the basic feature of eukaryotic circadian clock and is based on the rhythmic association of circadian transcriptional activator and repressor. In Drosophila, repression of dCLOCK/CYCLE (dCLK/CYC) mediated transcription by PERIOD (PER) is critical for inducing circadian rhythms of gene expression...
October 19, 2016: BMB Reports
Huan Wang, Hui Chen
OBJECTIVE: Circadian rhythm disruption is shown to be the cause of various health disorders. CLOCK and BMAL1, two core circadian transcription factors, were associated with the regulation of glucose homeostasis. This study evaluated the association between single nucleotide polymorphisms in CLOCK and BMAL1 gene and insulin resistance (IR) in hypertensive patients. DESIGN AND METHOD: We collected 334 outpatients with essential hypertension (EH), who have not taken any antihypertensive agents or stopped the medications for at least a week for this case-control study...
September 2016: Journal of Hypertension
Asadur Rahman, Yui Takeshige, Yoshihide Fujisawa, Hirofumi Hitomi, Daisuke Nakano, Akira Nishiyama
OBJECTIVE: Disrupted circadian rhythm of blood pressure is associated with cardiovascular events in metabolic syndrome and obesity. Experiments were conducted to examine the effects of sodium-glucose co-transporter 2 (SGLT2) inhibitors on circadian rhythm of blood pressure in a genetic model of obese metabolic syndrome (SHR/NDmcr-cp (+/+) (SHRcp)) and salt-treated obese Otsuka Long Evans Tokushima Fatty (OLETF) rats. DESIGN AND METHOD: Luseogliflozin (10 mg/kg/day, p...
September 2016: Journal of Hypertension
Akira Nishiyama, Abu Sufiun, Yoshihide Fujisawa, Asadur Rahman, Daisuke Nakano, Hirofumi Hitomi
OBJECTIVE: It has been indicated that non-dipper pattern of circadian rhythm of blood pressure (BP) is a great risk of cardiovascular disease, which is accompanied by impaired renal function and proteinuria. Here, we aimed to investigate the circadian rhythm of BP during the progression of renal injury in Dahl salt-sensitive (DSS) hypertensive rats. DESIGN AND METHOD: DSS rats were treated with a high salt diet (HS; 8% NaCl) for 10 weeks (n = 10). RESULTS: Before starting a HS diet, the difference in mean arterial pressure (MAP) between dark and light period was 6...
September 2016: Journal of Hypertension
Ayako Uchinaka, Yuri Kawashima, Yuki Sano, Mamoru Yoneda, Shogo Ito, Yusuke Sano, Kai Nagasawa, Natsumi Matsuura, Yuichiro Yamada, Toyoaki Murohara, Kohzo Nagata
OBJECTIVE: The pineal hormone melatonin, which regulates the body's circadian rhythm, possesses anti-oxidative and anti-inflammatory effects and thereby improves metabolic disorders. Ramelteon is a potent and highly selective agonist of melatonin receptors and attenuates age-associated hypertension and body weight gain in spontaneously hypertensive rats. However, the effects of ramelteon on cardiovascular and metabolic disorders in metabolic syndrome (MetS) remain unclear. We investigated the effects of ramelteon on cardiac and adipose tissue pathology in a rat model of MetS...
September 2016: Journal of Hypertension
Dong-Seok Yim
In the early phase of clinical development of antihypertensive drugs, quantitative modeling to predict their dose-concentration-response relationship is important to plan future clinical development and finding optimal dosage regimen at marketing approval. Two cases of concentration-response models of antihypertensive are presented here.Case 1: Carvedilol is a α1- and nonselective β- adrenergic receptor antagonist currently used for the management of mild-to-moderate essential hypertension and congestive heart failure...
September 2016: Journal of Hypertension
Stefano Schiaffino, Bert Blaauw, Kenneth A Dyar
The circadian oscillations of muscle genes are controlled either directly by the intrinsic muscle clock or by extrinsic factors, such as feeding, hormonal signals, or neural influences, which are in turn regulated by the central pacemaker, the suprachiasmatic nucleus of the hypothalamus. A unique feature of circadian rhythms in skeletal muscle is motor neuron-dependent contractile activity, which can affect the oscillation of a number of muscle genes independently of the muscle clock. The role of the intrinsic muscle clock has been investigated using different Bmal1 knockout (KO) models...
2016: Skeletal Muscle
Henrik Oster, Etienne Challet, Volker Ott, Emanuela Arvat, E Ronald de Kloet, Derk-Jan Dijk, Stafford Lightman, Alexandros Vgontzas, Eve Van Cauter
Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has been long recognized that this 24-h rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus...
October 17, 2016: Endocrine Reviews
Sairam Parthasarathy, Mary A Carskadon, Girardin Jean-Louis, Judith Owens, Adam Bramoweth, Daniel Combs, Lauren Hale, Elizabeth Harrison, Chantelle N Hart, Brant P Hasler, Sarah M Honaker, Elisabeth Hertenstein, Samuel Kuna, Clete Kushida, Jessica C Levenson, Caitlin Murray, Allan I Pack, Vivek Pillai, Kristi Pruiksma, Azizi Seixas, Patrick Strollo, Saurabh S Thosar, Natasha Williams, Daniel Buysse
A wealth of scientific knowledge is being generated in sleep and circadian science. In order for us to realize the return on investment for such scientific knowledge and to improve the health of the nation, we need to disseminate and implement research findings into practice. An implementation gap - termed a "quality chasm" by the Institutes of Medicine - separates the scientific knowledge we possess and the implementation of such knowledge into preventative interventions or healthcare treatments. It is frequently reported that a time lag of 17 years transpires before medical research reaches clinical practice...
October 10, 2016: Sleep
Song Wu, Andrew Fesler, Jingfang Ju
AIM: To establish a connection between microRNA (miRNAs), circadian rhythm, and colorectal cancer patient survival. METHODS: Genomic and clinical data were extracted from The Cancer Genome Atlas (TCGA) colorectal cancer database, and the expression levels of candidate miRNAs and a set of circadian rhythm-related genes (Per1, Per2, Per3, Bmal1), and genes associated with chemosensitivity (thymidylate synthase, dihydrofolate reductase) were assessed for any correlations among their expression...
January 2016: Cancer Transl Med
Jennifer Gile, Tobias Eckle
Cardiovascular disease is the number one cause of death worldwide. A powerful strategy for cardioprotection would be to identify specific molecules or targets that mimic ischemic preconditioning (IP), where short non-lethal episodes of ischemia and reperfusion prior to myocardial infarction result in dramatic reduction of infarct sizes. Since 1960 researchers believed that adenosine has a strong cardio-protective potential. In fact, with the discovery of cardiac IP in 1986 by Murry et al., adenosine was the first identified molecule that was used in studying the underlying mechanism of IP...
2016: Journal of Nature and Science
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