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Peripheral clock

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
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
Carolina Roza, Irene Mazo, Iván Rivera-Arconada, Elsa Cisneros, Ismel Alayón, José A López-García
The superficial dorsal horn contains large numbers of interneurons which process afferent and descending information to generate the spinal nociceptive message. Here, we set out to evaluate whether adjustments in patterns and/or temporal correlation of spontaneous discharges of these neurons are involved in the generation of central sensitization caused by peripheral nerve damage. Multielectrode arrays were used to record from discrete groups of such neurons in slices from control or nerve damaged mice. Whole-cell recordings of individual neurons were also obtained...
October 10, 2016: Pflügers Archiv: European Journal of Physiology
Zsolt Nagy, Alexa Marta, Henriett Butz, Istvan Liko, Karoly Racz, Attila Patocs
Peripheral clocks are set by different nervous, hormonal and metabolic stimuli, and regulate the circadian expression of several genes. We investigated whether a peripheral clock could be induced in the human adrenocortical cell line H295R and whether glucocorticoid receptor isoforms (GRα and GRß) are involved in this clock system. After synchronization of cells with serum shock, the rhythmic oscillation of clock genes PER1, PER2, REV-ERBα, and ARNTL was confirmed. In addition, H295R cells even without serum shock showed rhythmic expression of PER1, PER2, CRY1 and ARNTL...
October 7, 2016: Steroids
Takafumi Fukuda, Atsushi Haraguchi, Mari Kuwahara, Kaai Nakamura, Yutaro Hamaguchi, Yuko Ikeda, Yuko Ishida, Guanying Wang, Chise Shirakawa, Yoko Tanihata, Kazuaki Ohara, Shigenobu Shibata
The peripheral circadian clock is entrained by factors in the external environment such as scheduled feeding, exercise, and mental and physical stresses. In addition, recent studies in mice demonstrated that some food components have the potential to control the peripheral circadian clock during scheduled feeding, although information about these components remains limited. l-Ornithine is a type of non-protein amino acid that is present in foods and has been reported to have various physiological functions...
October 5, 2016: Scientific Reports
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
Rebecca Dumbell, Alexei Leliavski, Olga Matveeva, Christopher Blaum, Anthony H Tsang, Henrik Oster
The circadian rhythm of glucocorticoids affects diverse physiological systems, including stress responses and the coordination of rhythmic functions in peripheral and central tissues. Circadian clocks are considered to be important coordinators of glucocorticoid release and loss of the core clock component BMAL1 leads to ablation of behavioural and physiological rhythms, hypocortisolism, impaired ACTH and behavioural stress responses. Transplantation and conditional clock gene knock-down studies in mice suggest an important role of local adrenocortical clock function in this context...
October 3, 2016: Endocrinology
Takashi Okabe, Rohit Chavan, Sara S Fonseca Costa, Andrea Brenna, Jürgen A Ripperger, Urs Albrecht
REV-ERBα (Nr1d1) is a nuclear receptor that is part of the circadian clock mechanism and regulates metabolism and inflammatory processes. The glucocorticoid receptor (GR, Nr3c1) influences similar processes, but is not part of the circadian clock although glucocorticoid signaling affects resetting of the circadian clock in peripheral tissues. Because of their similar impact on physiological processes we studied the interplay between these two nuclear receptors. We found that REV-ERBα binds to the C-terminal part and GR to the N-terminal part of HSP90, a chaperone responsible for the activation of proteins to ensure survival of a cell...
September 29, 2016: Journal of Cell Science
Satish Sen, Hélène Raingard, Stéphanie Dumont, Andries Kalsbeek, Patrick Vuillez, Etienne Challet
Restricted feeding during the resting period causes pronounced shifts in a number of peripheral clocks, but not the central clock in the suprachiasmatic nucleus (SCN). By contrast, daily caloric restriction impacts also the light-entrained SCN clock, as indicated by shifted oscillations of clock (PER1) and clock-controlled (vasopressin) proteins. To determine if these SCN changes are due to the metabolic or timing cues of the restricted feeding, mice were challenged with an ultradian 6-meals schedule (1 food access every 4 h) to abolish the daily periodicity of feeding...
September 26, 2016: Chronobiology International
Chao Lu, Yang Yang, Ran Zhao, Bingxuan Hua, Chen Xu, Zuoqin Yan, Ning Sun, Ruizhe Qian
Biological rhythms controlled by the circadian clock are absent in embryonic stem cells (ESCs). However, they start to develop during the differentiation of pluripotent ESCs to downstream cells. Conversely, biological rhythms in adult somatic cells disappear when they are reprogrammed into induced pluripotent stem cells (iPSCs). These studies indicated that the development of biological rhythms in ESCs might be closely associated with the maintenance and differentiation of ESCs. The core circadian gene Clock is essential for regulation of biological rhythms...
September 23, 2016: Protein & Cell
Lenka Polidarová, Pavel Houdek, Martin Sládek, Zuzana Novosadová, Jiří Pácha, Alena Sumová
Colonic function is controlled by an endogenous clock that allows the colon to optimize its function on the daytime basis. For the first time, this study provided evidence that the clock is synchronized by rhythmic hormonal signals. In rat colon, adrenalectomy decreased and repeated applications of dexamethasone selectively rescued circadian rhythm in the expression of the clock gene Per1. Dexamethasone entrained the colonic clock in explants from mPer2(Luc) mice in vitro. In contrast, pinealectomy had no effect on the rat colonic clock, and repeated melatonin injections were not able to rescue the clock in animals maintained in constant light...
September 23, 2016: Chronobiology International
Heiko T Jansen, Tanya Leise, Gordon Stenhouse, Karine Pigeon, Wayne Kasworm, Justin Teisberg, Thomas Radandt, Robert Dallmann, Steven Brown, Charles T Robbins
BACKGROUND: Most biological functions are synchronized to the environmental light:dark cycle via a circadian timekeeping system. Bears exhibit shallow torpor combined with metabolic suppression during winter dormancy. We sought to confirm that free-running circadian rhythms of body temperature (Tb) and activity were expressed in torpid grizzly (brown) bears and that they were functionally responsive to environmental light. We also measured activity and ambient light exposures in denning wild bears to determine if rhythms were evident and what the photic conditions of their natural dens were...
2016: Frontiers in Zoology
Eleonora Khabirova, Ko-Fan Chen, John S O'Neill, Damian C Crowther
Circadian rhythms are essential for health and are frequently disturbed in disease. A full understanding of the causal relationships between behavioural and molecular circadian rhythms requires simultaneous longitudinal observations over time in individual organisms. Current experimental paradigms require the measurement of each rhythm separately across distinct populations of experimental organisms, rendering the comparability of the resulting datasets uncertain. We therefore developed FLYGLOW, an assay using clock gene controlled luciferase expression detected by exquisitely sensitive EM-CCD imaging, to enable simultaneous quantification of parameters including locomotor, sleep consolidation and molecular rhythms in single flies over days/weeks...
2016: Scientific Reports
Isa Kolbe, Jana Husse, Gabriela Salinas, Thomas Lingner, Mariana Astiz, Henrik Oster
The circadian master pacemaker in the suprachiasmatic nucleus (SCN) orchestrates peripheral clocks in various organs and synchronizes them with external time, including those in adipose tissue, which displays circadian oscillations in various metabolic and endocrine outputs. Because our knowledge about the instructive role of the SCN clock on peripheral tissue function is based mainly on SCN lesion studies, we here used an alternative strategy employing the Cre/loxP system to functionally delete the SCN clock in mice...
September 20, 2016: Journal of Biological Rhythms
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
Adonis Sfera, Carolina Osorio, Luzmin Inderias, Michael Cummings
BACKGROUND: Exposed to antipsychotic drugs (APDs), older individuals with dementing illness are at risk of cerebrovascular adverse effects (CVAE), including sudden death. Transient microvascular dysfunctions are known to occur in younger persons exposed to APDs; however, they seldom progress to CVAE, suggesting that APDs alone are insufficient for engendering this untoward effect. It is, therefore, believed that a preexistent microvascular damage is necessary for CVAE to take place, but the exact nature of this lesion remains unclear...
2016: Frontiers in Endocrinology
Ch Vinod, Anita Jagota
In mammals suprachiasmatic nucleus (SCN), acts as a light entrainable master clock and by generation of temporal oscillations regulates the peripheral organs acting as autonomous clocks resulting in overt behavioral and physiological rhythms. SCN also controls synthesis and release of melatonin (hormonal message for darkness) from pineal. Nitric Oxide (NO) acts as an important neurotransmitter in generating the phase shifts of circadian rhythms and participates in sleep-wake processes, maintenance of vascular tone as well as signalling and regulating inflammatory processes...
November 2016: Biogerontology
Valeria Zonato, Giorgio Fedele, Charalambos P Kyriacou
couch potato (cpo) encodes an RNA binding protein that has been reported to be expressed in the peripheral and central nervous system of embryos, larvae and adults, including the major endocrine organ, the ring gland. A polymorphism in the D. melanogaster cpo gene coding region displays a latitudinal cline in frequency in North American populations, but as cpo lies within the inversion In(3R)Payne, which is at high frequencies and itself shows a strong cline on this continent, interpretation of the cpo cline is not straightforward...
2016: PloS One
Fabin Dang, Xiujie Sun, Xiang Ma, Rong Wu, Deyi Zhang, Yaqiong Chen, Qian Xu, Yuting Wu, Yi Liu
Although food availability is a potent synchronizer of the peripheral circadian clock in mammals, the underlying mechanisms are unclear. Here, we show that hepatic Bmal1, a core transcription activator of the molecular clock, is post-transcriptionally regulated by signals from insulin, an important hormone that is temporally controlled by feeding. Insulin promotes postprandial Akt-mediated Ser42-phosphorylation of Bmal1 to induce its dissociation from DNA, interaction with 14-3-3 protein and subsequently nuclear exclusion, which results in the suppression of Bmal1 transcriptional activity...
2016: Nature Communications
Elisa Jimenez-Izal, Mark Saeys, Anastassia N Alexandrova
The top monolayers of surface carbides and nitrides of Co and Ni are predicted to yield new stable 2D materials upon exfoliation. These 2D phases are p4g clock reconstructed, and contain planar tetracoordinated C or N. The stability of these flat carbides and nitrides is high, and ab-initio molecular dynamics at a simulation temperature of 1800 K suggest that the materials are thermally stable at elevated temperatures. The materials owe their stability to local triple aromaticity (π-, σ-radial, and σ-peripheral) associated with binding of the main group element to the metal...
August 26, 2016: Journal of Physical Chemistry. A
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