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1

Biological Clocks & Circadian Rhythms  

ERIC Educational Resources Information Center

The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian

Robertson, Laura; Jones, M. Gail

2009-01-01

2

Circadian rhythms and fertility.  

PubMed

Circadian rhythms impact on a wide range of physiological systems and this impact extends to fertility, such that disruptions to timing systems can impact upon reproductive capacity. This is highlighted most obviously in mutant mouse models whereby deletion or mutation of single genes results not only in disrupted circadian rhythmicity, but also compromised male and female reproductive function. In this review, we discuss the presence of circadian clocks in female and male reproductive tissues and the role these clocks play in the generation of oestrus cycles, ovulation, sperm generation, implantation and the maintenance of pregnancy. Given the increased incidence of shiftwork and international travel which disrupt circadian rhythmicity, and the increasing prevalence of reproductive technologies whereby early embryo development occurs without external time cues, it is important for us to consider the role of circadian rhythms in fertility. PMID:21872642

Kennaway, David J; Boden, Michael J; Varcoe, Tamara J

2012-02-01

3

Sleep and circadian rhythms  

NASA Technical Reports Server (NTRS)

Three interacting processes are involved in the preservation of circadian rhythms: (1) endogenous rhythm generation mechanisms, (2) entrainment mechanisms to keep these rhythms 'on track', and (3) exogenous masking processes stemming from changes in environment and bahavior. These processes, particularly the latter two, can be dramatically affected in individuals of advanced age and in space travelers, with a consequent disruption in sleep and daytime functioning. This paper presents results of a phase-shift experiment investigating the age-related effects of the exogeneous component of circadian rhythms in various physiological and psychological functions by comparing these functions in middle aged and old subjects. Dramatic differences were found between the two age groups in measures of sleep, mood, activation, and performance efficiency.

Monk, Timothy H.

1991-01-01

4

Circadian Rhythm Sleep Disorders  

PubMed Central

There have been remarkable advances in our understanding of the molecular, cellular and physiological mechanisms underlying the regulation of circadian rhythms, as well as the impact of circadian dysfunction on health and disease. This information has transformed our understanding of the effect of circadian rhythm sleep disorders (CRSD) on health, performance and safety. CRSDs are caused by alterations of the central circadian time-keeping system, or a misalignment of the endogenous circadian rhythm and the external environment. In this section, we provide a review of circadian biology and discuss the pathophysiology, clinical features, diagnosis, and treatment of the most commonly encountered CRSDs in clinical practice.

Zhu, Lirong; Zee, Phyllis C.

2012-01-01

5

Biological Clocks and Circadian Rhythms  

NSDL National Science Digital Library

The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian rhythms, they are provided with opportunities to connect learning to experiences and observations from their own lives. This article describes how to reset the biological clock of a shamrock plant while shedding light on its circadian rhythms.

Robertson, Laura; Jones, M. G.

2009-02-01

6

A Re-Examination of the Role of the Nucleus in Generating the Circadian Rhythm in Acetabularia  

Microsoft Academic Search

The role of the nucleus in the generation of the circadian rhythm in Acetabularia has been unclear. Early experiments showed that the plant could exhibit a circadian rhythm in the absence of a nucleus. However, other experiments appeared to show that the nucleus could impart phase information to the rhythm, and so therefore must be a part of the system

John C. Woolum

1991-01-01

7

Circadian Rhythm Abnormalities  

PubMed Central

Purpose: This article reviews the recent advances in understanding of the fundamental properties of circadian rhythms and discusses the clinical features, diagnosis, and treatment of circadian rhythm sleep disorders (CRSDs). Recent Findings: Recent evidence strongly points to the ubiquitous influence of circadian timing in nearly all physiologic functions. Thus, in addition to the prominent sleep and wake disturbances, circadian rhythm disorders are associated with cognitive impairment, mood disturbances, and increased risk of cardiometabolic disorders. The recent availability of biomarkers of circadian timing in clinical practice has improved our ability to identify and treat these CRSDs. Summary: Circadian rhythms are endogenous rhythms with a periodicity of approximately 24 hours. These rhythms are synchronized to the physical environment by social and work schedules by various photic and nonphotic stimuli. CRSDs result from a misalignment between the timing of the circadian rhythm and the external environment (eg, jet lag and shift work) or a dysfunction of the circadian clock or its afferent and efferent pathways (eg, delayed sleep-phase, advanced sleep-phase, non–24-hour, and irregular sleep-wake rhythm disorders). The most common symptoms of these disorders are difficulties with sleep onset and/or sleep maintenance and excessive sleepiness that are associated with impaired social and occupational functioning. Effective treatment for most of the CRSDs requires a multimodal approach to accelerate circadian realignment with timed exposure to light, avoidance of bright light at inappropriate times, and adherence to scheduled sleep and wake times. In addition, pharmacologic agents are recommended for some of the CRSDs. For delayed sleep-phase, non–24-hour, and shift work disorders, timed low-dose melatonin can help advance or entrain circadian rhythms; and for shift work disorder, wake-enhancing agents such as caffeine, modafinil, and armodafinil are options for the management of excessive sleepiness.

Zee, Phyllis C.; Attarian, Hrayr; Videnovic, Aleksandar

2013-01-01

8

[Circadian rhythm sleep disorder].  

PubMed

Primary pathophysiology of circadian rhythm sleep disorders(CRSDs) is a misalignment between the endogenous circadian rhythm phase and the desired or socially required sleep-wake schedule, or dysfunction of the circadian pacemaker and its afferent/efferent pathways. CRSDs consist of delayed sleep phase type, advanced sleep phase type, free-running type, irregular sleep-wake type, shift work type and jet lag type. Chronotherapy using strong zeitgebers (time cues), such as bright light and melatonin/ melatonin type 2 receptor agonist, is effective when administered with proper timing. Bright light is the strongest entraining agent of circadian rhythms. Bright light therapy (appropriately-timed exposure to bright light) for CRSDs is an effective treatment option, and can shift the sleep-wake cycle to earlier or later times, in order to correct for misalignment between the circadian system and the desired sleep-wake schedule. Timed administration of melatonin, either alone or in combination with light therapy has also been shown to be useful in the treatment of CRSDs. PMID:24437262

Mishima, Kazuo

2013-12-01

9

Circadian rhythms regulate amelogenesis.  

PubMed

Ameloblasts, the cells responsible for making enamel, modify their morphological features in response to specialized functions necessary for synchronized ameloblast differentiation and enamel formation. Secretory and maturation ameloblasts are characterized by the expression of stage-specific genes which follows strictly controlled repetitive patterns. Circadian rhythms are recognized as key regulators of the development and diseases of many tissues including bone. Our aim was to gain novel insights on the role of clock genes in enamel formation and to explore the potential links between circadian rhythms and amelogenesis. Our data shows definitive evidence that the main clock genes (Bmal1, Clock, Per1 and Per2) oscillate in ameloblasts at regular circadian (24 h) intervals both at RNA and protein levels. This study also reveals that the two markers of ameloblast differentiation i.e. amelogenin (Amelx; a marker of secretory stage ameloblasts) and kallikrein-related peptidase 4 (Klk4, a marker of maturation stage ameloblasts) are downstream targets of clock genes. Both, Amelx and Klk4 show 24h oscillatory expression patterns and their expression levels are up-regulated after Bmal1 over-expression in HAT-7 ameloblast cells. Taken together, these data suggest that both the secretory and the maturation stages of amelogenesis might be under circadian control. Changes in clock gene expression patterns might result in significant alterations of enamel apposition and mineralization. PMID:23486183

Zheng, Li; Seon, Yoon Ji; Mourão, Marcio A; Schnell, Santiago; Kim, Doohak; Harada, Hidemitsu; Papagerakis, Silvana; Papagerakis, Petros

2013-07-01

10

Circadian rhythms, sleep, and the menstrual cycle  

Microsoft Academic Search

Women with ovulatory menstrual cycles have a circadian rhythm superimposed on the menstrual-associated rhythm; in turn, menstrual events affect the circadian rhythm. In this paper, we review circadian rhythms in temperature, selected hormone profiles, and sleep–wake behavior in healthy women at different phases of the menstrual cycle. The effects on menstrual cycle rhythmicity of disrupted circadian rhythms, for example, with

Fiona C. Baker; Helen S. Driver

2007-01-01

11

[Depression and circadian rhythm].  

PubMed

Adverse changes in circadian rhythms are an integral part of the clinical features of endogenous depression, and particularly of seasonal depression. Alongside twenty-four variations in the major symptoms, these forms of depression can be characterised psychometrically, physiologically and biologically. The most classical adverse changes are amplitude modifications, fluctuations and periodicity of the hormonal secretory rhythms. Pathophysiological and psychopathological models have been proposed to combat these abnormalities. The leading models include free course, phase advance (or instability) and hypnic models, or those based on disturbances of the internal clock. The main psychopathological models are those of endokinesis and psychosocial desynchronisation. The therapeutic applications of the pathophysiological models use manipulation of the wake-sleep cycle, phototherapy and melatonin and its derivatives : those of the psychopathological models used time-space management and development of resynchronisation capacities. The question determining whether these adverse changes are a cause or effect of depressive behaviour is unresolved. PMID:19268174

Azorin, J M; Kaladjian, A

2009-01-01

12

Animal Behaviour and Circadian Rhythms.  

National Technical Information Service (NTIS)

The behavior of various animals is analyzed with them transferred from a natural rhythmic environment to a constant environment. It is suggested that the parameters of the circadian rhythm depend on the experimental conditions. (Author)

V. B. Chernyshev

1975-01-01

13

Studying circadian rhythms in Drosophila melanogaster.  

PubMed

Circadian rhythms have a profound influence on most bodily functions: from metabolism to complex behaviors. They ensure that all these biological processes are optimized with the time-of-day. They are generated by endogenous molecular oscillators that have a period that closely, but not exactly, matches day length. These molecular clocks are synchronized by environmental cycles such as light intensity and temperature. Drosophila melanogaster has been a model organism of choice to understand genetically, molecularly and at the level of neural circuits how circadian rhythms are generated, how they are synchronized by environmental cues, and how they drive behavioral cycles such as locomotor rhythms. This review will cover a wide range of techniques that have been instrumental to our understanding of Drosophila circadian rhythms, and that are essential for current and future research. PMID:24412370

Tataroglu, Ozgur; Emery, Patrick

2014-06-15

14

Circadian rhythm sleep disorders (CRSD)  

Microsoft Academic Search

Circadian Rhythm Sleep Disorders (CRSD) are a group of sleep disorders characterized by a malsynchronization between a person's biological clock and the environmental 24-h schedule. These disorders can lead to harmful psychological and functional difficulties and are often misdiagnosed and incorrectly treated due to the fact that doctors are unaware of their existence. In the following review we describe the

Yaron Dagan

2002-01-01

15

Melatonin in Circadian Rhythm Sleep Disorders  

Microsoft Academic Search

\\u000a Normal circadian rhythms are synchronized to a regular 24 hr environmental light\\/dark (L\\/D) cycle. Both suprachiasmatic nucleus\\u000a (SCN) and melatonin are essential for this adaptation. Desynchronization of circadian rhythms as occurs in chronobiological\\u000a disorders result in severe disturbances of sleep. The Circadian rhythm sleep Disorders (CRSDs) include delayed sleep phase\\u000a syndrome (DSPS), Non 24 hr sleep\\/wake rhythm disorder, jet lag

V. Srinivasan; M. G. Smits; L. Kayumov; S. R. Pandi-Perumal; Daniel P. Cardinali; M. J. Thorpy

16

Circadian rhythm disruption in cancer biology.  

PubMed

Circadian rhythms show universally a 24-h oscillation pattern in metabolic, physiological and behavioral functions of almost all species. This pattern is due to a fundamental adaptation to the rotation of Earth around its own axis. Molecular mechanisms of generation of circadian rhythms organize a biochemical network in suprachiasmatic nucleus and peripheral tissues, building cell autonomous clock pacemakers. Rhythmicity is observed in transcriptional expression of a wide range of clock-controlled genes that regulate a variety of normal cell functions, such as cell division and proliferation. Desynchrony of this rhythmicity seems to be implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In 2007, the International Agency for Research on Cancer (IARC) categorized "shiftwork that involves circadian disruption [as] probably carcinogenic to humans" (Group 2A in the IARC classification system of carcinogenic potency of an agentagent) (Painting, Firefighting, and Shiftwork; IARC; 2007). This review discusses the potential relation between disruptions of normal circadian rhythms with genetic driving machinery of cancer. Elucidation of the role of clockwork disruption, such as exposure to light at night and sleep disruption, in cancer biology could be important in developing new targeted anticancer therapies, optimizing individualized chronotherapy and modifying lighting environment in workplaces or homes. PMID:22811066

Savvidis, Christos; Koutsilieris, Michael

2012-01-01

17

Circadian Rhythm Disruption in Cancer Biology  

PubMed Central

Circadian rhythms show universally a 24-h oscillation pattern in metabolic, physiological and behavioral functions of almost all species. This pattern is due to a fundamental adaptation to the rotation of Earth around its own axis. Molecular mechanisms of generation of circadian rhythms organize a biochemical network in suprachiasmatic nucleus and peripheral tissues, building cell autonomous clock pacemakers. Rhythmicity is observed in transcriptional expression of a wide range of clock-controlled genes that regulate a variety of normal cell functions, such as cell division and proliferation. Desynchrony of this rhythmicity seems to be implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In 2007, the International Agency for Research on Cancer (IARC) categorized “shiftwork that involves circadian disruption [as] probably carcinogenic to humans” (Group 2A in the IARC classification system of carcinogenic potency of an agentagent) (Painting, Firefighting, and Shiftwork; IARC; 2007). This review discusses the potential relation between disruptions of normal circadian rhythms with genetic driving machinery of cancer. Elucidation of the role of clockwork disruption, such as exposure to light at night and sleep disruption, in cancer biology could be important in developing new targeted anticancer therapies, optimizing individualized chronotherapy and modifying lighting environment in workplaces or homes.

Savvidis, Christos; Koutsilieris, Michael

2012-01-01

18

[Relation between dementia and circadian rhythm disturbance].  

PubMed

Dementia and circadian rhythm disturbance are closely linked. First, dementia patient shows circadian rhythm disorders (e.g. insomnia, night wandering, daytime sleep). These symptoms are a burden for caregivers. Circadian rhythm disturbance of dementia relates ADL and cognitive impairment, and diurnal rhythm disorder of blood pressure and body temperature. Some study shows that circadian rhythm disorders in dementia are a disturbance of neural network between suprachiasmatic nucleus and cerebral white matter, and involvement of both frontal lobes, left parietal and occipital cortex, left temporoparietal region. The first-line treatment of circadian rhythm disturbance should be non-drug therapy (e.g. exercise, bright light exposure, reduce caffeine intake, etc.). If physician prescribe drugs, keep the rule of low-dose and short-term and avoid benzodiazepines. Atypical antipsychotic drugs like risperidone and some antidepressants are useful for treatment of insomnia in dementia. But this usage is off-label. So we must well inform to patient and caregiver, and get consent about treatment. Second, some study shows circadian rhythm disorder is a risk factor of dementia. However, we should discuss that circadian rhythm disturbance is "risk factor of dementia" or "prodromal symptom of dementia". If a clinician finds circadian rhythm disorder in elderly people, should be examined cognitive and ADL function, and careful about that patients have dementia or will develop dementia. PMID:24724422

Nakamura, Kei; Meguro, Kenichi

2014-03-01

19

Circadian Rhythms and Cancer Chronotherapeutics  

Microsoft Academic Search

\\u000a The Circadian Timing System (CTS) controls cellular proliferation and drug metabolism over a 24-h period through molecular\\u000a clocks in each cell. These cellular clocks are coordinated by a hypothalamic pacemaker, the suprachiasmatic nuclei, which\\u000a generate or control circadian physiology. The CTS down-regulates malignant growth in experimental models and in cancer patients.\\u000a It also generates large and predictable 24-h changes in

Francis Lévi; Atilla Altinok; Albert Goldbeter

20

Therapeutics for Circadian Rhythm Sleep Disorders  

PubMed Central

Synopsis The sleep-wake cycle is regulated by the interaction of endogenous circadian and homeostatic processes. The circadian system provides timing information for most physiological rhythms, including the sleep and wake cycle. In addition, the central circadian clock located in the suprachiasmatic nucleus of the hypothalamus has been shown to promote alertness during the day. Circadian rhythm sleep disorders arise when there is a misalignment between the timing of the endogenous circadian rhythms and the external environment or when there is dysfunction of the circadian clock or its entrainment pathways. The primary synchronizing agents of the circadian system are light and melatonin. Light is the strongest entraining agent of circadian rhythms and timed exposure to bright light is often used in the treatment of circadian rhythm sleep disorders. In addition, timed administration of melatonin, either alone or in combination with light therapy has been shown to be useful in the treatment of the following circadian rhythm sleep disorders: delayed sleep phase, advanced sleep phase, free-running, irregular sleep wake, jet lag and shift work.

Dodson, Ehren R.; Zee, Phyllis C

2010-01-01

21

Circadian rhythms in leukocyte trafficking.  

PubMed

A broad range of immunological processes oscillates over the course of a day. Recent findings have identified a molecular basis for the circadian clock in the regulation of the immune system. These rhythms manifest themselves in oscillatory behavior of immune cells and proinflammatory mediators, which causes a time-dependent sensitivity in the reaction to pathogens. This rhythmicity impacts disease manifestations and severity and provides an option for therapy that incorporates chronopharmacological considerations. This review will focus on the current knowledge and relevance of rhythmic immune cell trafficking. It will provide an overview of the molecular clock machinery and its interrelations with leukocyte migration and the immune response. PMID:24435096

Druzd, David; de Juan, Alba; Scheiermann, Christoph

2014-03-01

22

Circadian Rhythms in Cultured Mammalian Retina  

Microsoft Academic Search

Many retinal functions are circadian, but in most instances the location of the clock that drives the rhythm is not known. Cultured neural retinas of the golden hamster (Mesocricetus auratus) exhibited circadian rhythms of melatonin synthesis for at least 5 days at 27^circC. The rhythms were entrained by light cycles applied in vitro and were free-running in constant darkness. Retinas

Gianluca Tosini; Michael Menaker

1996-01-01

23

PPAR? is a potential therapeutic target of drugs to treat circadian rhythm sleep disorders  

Microsoft Academic Search

Recent progress at the molecular level has revealed that nuclear receptors play an important role in the generation of mammalian circadian rhythms. To examine whether peroxisome proliferator-activated receptor alpha (PPAR?) is involved in the regulation of circadian behavioral rhythms in mammals, we evaluated the locomotor activity of mice administered with the hypolipidemic PPAR? ligand, bezafibrate. Circadian locomotor activity was phase-advanced

Hidenori Shirai; Katsutaka Oishi; Takashi Kudo; Shigenobu Shibata; Norio. Ishida

2007-01-01

24

Caffeine lengthens circadian rhythms in mice.  

PubMed

Although caffeine alters sleep in many animals, whether or not it affects mammalian circadian clocks remains unknown. Here, we found that incubating cultured mammalian cell lines, human osteosarcoma U2OS cells and mouse fibroblast NIH3T3 cells, with caffeine lengthened the period of circadian rhythms. Adding caffeine to ex vivo cultures also lengthened the circadian period in mouse liver explants from Per2::Luciferase reporter gene knockin mice, and caused a phase delay in brain slices containing the suprachiasmatic nucleus (SCN), where the central circadian clock in mammals is located. Furthermore, chronic caffeine consumption ad libitum for a week delayed the phase of the mouse liver clock in vivo under 12 h light-dark conditions and lengthened the period of circadian locomotor rhythms in mice under constant darkness. Our results showed that caffeine alters circadian clocks in mammalian cells in vitro and in the mouse ex vivo and in vivo. PMID:21684260

Oike, Hideaki; Kobori, Masuko; Suzuki, Takahiro; Ishida, Norio

2011-07-01

25

Attenuated Circadian Rhythms in Mice Lacking the Prokineticin 2 Gene  

PubMed Central

Circadian clocks drive daily rhythms in virtually all organisms. In mammals, the suprachiasmatic nucleus (SCN) is recognized as the master clock that synchronizes central and peripheral oscillators to evoke circadian rhythms of diverse physiology and behavior. How the timing information is transmitted from the SCN clock to generate overt circadian rhythms is essentially unknown. Prokineticin 2 (PK2), a clock-controlled gene that encodes a secreted protein, has been indicated as a candidate SCN clock output signal that regulates circadian locomotor rhythm. Here we report the generation and analysis of PK2-null mice. The reduction of locomotor rhythms in PK2-null mice was apparent in both hybrid and inbred genetic backgrounds. PK2-null mice also displayed significantly reduced rhythmicity for a variety of other physiological and behavioral parameters, including sleep—wake cycle, body temperature, circulating glucocorticoid and glucose levels, as well as the expression of peripheral clock genes. In addition, PK2-null mice showed accelerated acquisition of food anticipatory activity during a daytime food restriction. We conclude that PK2, acting as a SCN output factor, is important for the maintenance of robust circadian rhythms.

Li, Jia-Da; Hu, Wang-Ping; Boehmer, Lisa; Cheng, Michelle Y.; Lee, Alex G.; Jilek, Alexander; Siegel, Jerome M.; Zhou, Qun-Yong

2009-01-01

26

Entrainment of Circadian Rhythms by Zeitgebers.  

National Technical Information Service (NTIS)

The results of five different types of experiments can be summarized as follows: (1) The phase-angle difference between the circadian rhythm and the entraining Zeitgeber is a function of the free-running circadian period as measured under constant conditi...

J. Aschoff

1966-01-01

27

Circadian rhythms lit up in Chlamydomonas  

PubMed Central

Recent work on the circadian clock of the unicellular green alga Chlamydomonas reinhardtii strengthens its standing as a convenient model system for circadian study. It was shown to be amenable to molecular engineering using a luciferase-based real-time reporter for circadian rhythms. Together with the completed draft genomic sequence, the new system opens the door for genome-scale forward and reverse genetic analysis.

Breton, Ghislain; Kay, Steve A

2006-01-01

28

Sleep and circadian rhythm disruption in neuropsychiatric illness.  

PubMed

Sleep and circadian rhythm disruption (SCRD) is a common feature in many neuropsychiatric diseases including schizophrenia, bipolar disorder and depression. Although the precise mechanisms remain unclear, recent evidence suggests that this comorbidity is not simply a product of medication or an absence of social routine, but instead reflects commonly affected underlying pathways and mechanisms. For example, several genes intimately involved in the generation and regulation of circadian rhythms and sleep have been linked to psychiatric illness. Further, several genes linked to mental illness have recently been shown to also play a role in normal sleep and circadian behaviour. Here we describe some of the emerging common mechanisms that link circadian rhythms, sleep and SCRD in severe mental illnesses. A deeper understanding of these links will provide not only a greater understanding of disease mechanisms, but also holds the promise of novel avenues for therapeutic intervention. PMID:23618559

Jagannath, Aarti; Peirson, Stuart N; Foster, Russell G

2013-10-01

29

Circadian rhythms in obsessive-compulsive disorder.  

PubMed

The etiopathology and neurobiology of obsessive-compulsive disorder (OCD) are not fully understood. As for altered circadian rhythms associated with OCD, hormonal dysregulation and a delayed sleep phase have come into the focus of research. The novel antidepressant agomelatine is able to resynchronize circadian rhythms and the augmentative administration of this compound has been shown to be of benefit in some OCD patients who are refractory to common forms of pharmacotherapy. Adjunctive chronotherapy might also enhance the outcome in treatment-refractory OCD. The present review summarises the findings regarding circadian abnormalities in OCD. PMID:22543530

Lange, Klaus W; Lange, Katharina M; Hauser, Joachim; Tucha, Lara; Tucha, Oliver

2012-10-01

30

Circadian Rhythms in Catecholamine Metabolites and Cyclic Nucleotide Production.  

National Technical Information Service (NTIS)

Circadian rhythms in noradrenergic (NE) and dopaminergic (DA) metabolites and in cyclic nucleotide production were measured in discrete regions of rat brain. A circadian rhythm was found in the concentration of the NE metabolite, 3-methoxy-4-hydroxyphenyl...

M. S. Kafka, M. A. Benedito, R. H. Roth, L. K. Steele, W. W. Wolfe

1986-01-01

31

Neurochemical Control of Circadian Rhythms.  

National Technical Information Service (NTIS)

We have continued our investigation of the neurochemical systems contained in the circadian clock localized within the suprachiasmatic nucleus (SCN). Our primary focus has been to determine the circadian functions of a subpopulation of SCN interneurons in...

A. H. Elliott

1989-01-01

32

Circadian rhythms in Macaca mulatta monkeys during Bion 11 flight  

NASA Technical Reports Server (NTRS)

Circadian rhythms of primate brain temperature, head and ankle skin temperature, motor activity, and heart rate were studied during spaceflight and on the ground. In space, the circadian rhythms of all the parameters were synchronized with diurnal Zeitgebers. However, in space the brain temperature rhythm showed a significantly more delayed phase angle, which may be ascribed to an increase of the endogenous circadian period.

Alpatov, A. M.; Hoban-Higgins, T. M.; Klimovitsky, V. Y.; Tumurova, E. G.; Fuller, C. A.

2000-01-01

33

Dihydropyrimidine dehydrogenase circadian rhythm in mouse liver  

Microsoft Academic Search

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluorouracil (FU) catabolism. The relevance of the measurement of DPD activity for identifying DPD-deficient patients is lessened by circadian variability in DPD activity. Our purpose was to determine whether or not DPD mRNA is sustained by a circadian rhythm. Synchronised mice (male B6D2F1) were sacrificed at 3, 7, 11, 15, 19 or

B Porsin; J.-L Formento; E Filipski; M.-C Etienne; M Francoual; N Renée; N Magné; F Lévi; G Milano

2003-01-01

34

Circadian rhythm entrainment in flies and mammals  

Microsoft Academic Search

Circadian rhythms are a fundamental adaptation of living cells to the daily and seasonal fluctuation in light and temperature.\\u000a Circadian oscillations persist in constant conditions; however, they are also phase-adjusted (entrained) by day-night cycles.\\u000a It is this entrainability that provides for the proper phasing of the program, to the sequence of external changes that it\\u000a has evolved to exploit. Synchronization

Rachel Ben-Shlomo; Charalambos P. Kyriacou

2002-01-01

35

Mapping of Individual Circadian Rhythm.  

National Technical Information Service (NTIS)

Former models about the formation of the 24 hour rhythm in man, animals and plants are reviewed, according to which it is acquired, established and maintained by exogenic periodicities. The present investigation maps individual daily rhythms on the basis ...

O. Oequist

1975-01-01

36

Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease  

Microsoft Academic Search

Sleep and circadian rhythm disruption are frequently observed in patients with psychiatric disorders and neurodegenerative disease. The abnormal sleep that is experienced by these patients is largely assumed to be the product of medication or some other influence that is not well defined. However, normal brain function and the generation of sleep are linked by common neurotransmitter systems and regulatory

Katharina Wulff; Silvia Gatti; Joseph G. Wettstein; Russell G. Foster

2010-01-01

37

Neurochemical Control of Circadian Rhythms.  

National Technical Information Service (NTIS)

The suprachiasmatic nucleus (SCN), which appears to act as a circadian clock, contains a large subpopulation of local circuit neurons in which vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are co-localized. We are continuing t...

H. E. Albers

1990-01-01

38

Metabolic circadian rhythms in embryonic turtles.  

PubMed

Oviparous species are model organisms for investigating embryonic development of endogenous physiological circadian rhythms without the influence of maternal biorhythms. Recent studies have demonstrated that heart rates and metabolic rates of embryonic turtles are not constant or always maximal and can be altered in response to the presence of embryos at a more advanced stage of development within the nest. A first step in understanding the physiological mechanisms underpinning these responses in embryonic ectothermic organisms is to develop metabolic profiles (e.g., heart rate) at different temperatures throughout incubation. Heart beat and rhythmic patterns or changes in development may represent important signals or cues within a nest and may be vital to coordinate synchronous hatching well in advance of the final stages of incubation. We developed baseline embryonic heart-rate profiles of embryos of the short-necked Murray River turtle (Emydura macquarii) to determine the stage of embryogenesis that metabolic circadian rhythms become established, if at all. Eggs were incubated at constant temperatures (26°C and 30°C) and heart rates were monitored at 6-h intervals over 24 h every 7-11 days until hatching. Circadian heart rate rhythms were detected at the mid-gestation period and were maintained until hatching. Heart rates throughout the day varied by up to 20% over 24 h and were not related to time of day. This study demonstrated that endogenous metabolic circadian rhythms in developing embryos in turtle eggs establish earlier in embryogenesis than those documented in other vertebrate taxa during embryogenesis. Early establishment of circadian rhythms in heart rates may be critical for communication among embryos and synchrony in hatching and emergence from the nest. PMID:23652198

Loudon, Fiona Kay; Spencer, Ricky-John; Strassmeyer, Alana; Harland, Karen

2013-07-01

39

Circadian Rhythms in Photosynthesis 1  

PubMed Central

Net carbon assimilation and stomatal conductance to water vapor oscillated repeatedly in red kidney bean, Phaseolus vulgaris L., plants transferred from a natural photoperiod to constant light. In a gas exchange system with automatic regulation of selected environmental and physiological variables, assimilation and conductance oscillated with a free-running period of approximately 24.5 hours. The rhythms in carbon assimilation and stomatal conductance were closely coupled and persisted for more than a week under constant conditions. A rhythm in assimilation occurred when either ambient or intercellular CO2 partial pressure was held constant, demonstrating that the rhythm in assimilation was not entirely the result of stomatal effects on CO2 diffusion. Rhythms in assimilation and conductance were not expressed in plants grown under constant light at a constant temperature, demonstrating that the rhythms did not occur spontaneously but were induced by an external stimulus. In plants grown under constant light with a temperature cycle, a rhythm was entrained in stomatal conductance but not in carbon assimilation, indicating that the oscillators driving the rhythms differed in their sensitivity to environmental stimuli.

Hennessey, Timothy L.; Field, Christopher B.

1991-01-01

40

Familial advanced sleep-phase syndrome: A short-period circadian rhythm variant in humans  

Microsoft Academic Search

Biological circadian clocks oscillate with an approximately 24-hour period, are ubiquitous, and presumably confer a selective advantage by anticipating the transitions between day and night. The circadian rhythms of sleep, melatonin secretion and body core temperature are thought to be generated by the suprachiasmatic nucleus of the hypothalamus, the anatomic locus of the mammalian circadian clock. Autosomal semi-dominant mutations in

Christopher R. Jones; Scott S. Campbell; Stephanie E. Zone; Fred Cooper; Alison DeSano; Patricia J. Murphy; Bryan Jones; Laura Czajkowski; Louis J. Pt?ek

1999-01-01

41

Chronobiology and Obesity: Interactions between Circadian Rhythms and Energy Regulation.  

PubMed

Recent advances in the understanding of the molecular, genetic, neural, and physiologic basis for the generation and organization of circadian clocks in mammals have revealed profound bidirectional interactions between the circadian clock system and pathways critical for the regulation of metabolism and energy balance. The discovery that mice harboring a mutation in the core circadian gene circadian locomotor output cycles kaput (Clock) develop obesity and evidence of the metabolic syndrome represented a seminal moment for the field, clearly establishing a link between circadian rhythms, energy balance, and metabolism at the genetic level. Subsequent studies have characterized in great detail the depth and magnitude of the circadian clock's crucial role in regulating body weight and other metabolic processes. Dietary nutrients have been shown to influence circadian rhythms at both molecular and behavioral levels; and many nuclear hormone receptors, which bind nutrients as well as other circulating ligands, have been observed to exhibit robust circadian rhythms of expression in peripheral metabolic tissues. Furthermore, the daily timing of food intake has itself been shown to affect body weight regulation in mammals, likely through, at least in part, regulation of the temporal expression patterns of metabolic genes. Taken together, these and other related findings have transformed our understanding of the important role of time, on a 24-h scale, in the complex physiologic processes of energy balance and coordinated regulation of metabolism. This research has implications for human metabolic disease and may provide unique and novel insights into the development of new therapeutic strategies to control and combat the epidemic of obesity. PMID:24829483

Summa, Keith C; Turek, Fred W

2014-05-01

42

Atrazine affects the circadian rhythm of microcystis aeruginosa.  

PubMed

This study provides original data regarding the effects of atrazine (Atr) on the circadian rhythm of the cyanobacterium Microcystis aeruginosa. The results reveal that the circadian rhythms of the central circadian oscillator genes reached their peaks from 1 to 2.5?h after the light was switched on, and the circadian rhythms of physiologically related genes were highly synchronized with the central circadian oscillator genes. These circadian rhythms were consistent with cell growth at the physiological level. The circadian rhythms of the central circadian oscillator genes were altered, and their peaks disappeared or were delayed by the Atr treatment. Therefore, the rhythms of the physiologically related genes in this study also changed to synchronize the new circadian rhythms. And the physiological parameters were tightly correlated with the gene circadian rhythm in the Atr treatment, suggesting that Atr affects M. aeruginosa growth by possibly altering the circadian expression patterns of the clock. Furthermore, this influence is related to the exposure time point of Atr. Thus, chemicals treated in the suitable exposure time point can exert their fullest effects against cell growth. PMID:24028538

Qian, Haifeng; Wei, Yong; Bao, Guanjun; Huang, Baochen; Fu, Zhengwei

2014-02-01

43

Circadian rhythm asynchrony in man during hypokinesis.  

NASA Technical Reports Server (NTRS)

Posture and exercise were investigated as synchronizers of certain physiologic rhythms in eight healthy male subjects in a defined environment. Four subjects exercised during bed rest. Body temperature (BT), heart rate, plasma thyroid hormone, and plasma steroid data were obtained from the subjects for a 6-day ambulatory equilibration period before bed rest, 56 days of bed rest, and a 10-day recovery period after bed rest. The results indicate that the mechanism regulating the circadian rhythmicity of the cardiovascular system is rigorously controlled and independent of the endocrine system, while the BT rhythm is more closely aligned to the endocrine system.

Winget, C. M.; Vernikos-Danellis, J.; Cronin, S. E.; Leach, C. S.; Rambaut, P. C.; Mack, P. B.

1972-01-01

44

Circadian susceptibility rhythm to neuroleptics: Tetrabenazine  

Microsoft Academic Search

In order to clarify the influences of situational factors on the effects of psychotropic drugs, the sedative effects of tetrabenazine after injection at various times of the day were studied. When 50 mg\\/kg body weight of tetrabenazine was injected into rats at eight different times of the day (07:30–19:30 dark, 19:30–07:30 light), a circadian rhythm of sedative effect was observed

Haruo Nagayama; Akinori Takagi; Toshiaki Tateishi; Ryo Takahashi

1977-01-01

45

Alcohol Research and Health, Volume 25, Number 2, 2001. Chronobiology: Circadian Rhythms and Alcohol Use.  

National Technical Information Service (NTIS)

Contents: Overview of Circadian Rhythms; Alcohol's Interactions With Circadian Rhythms: A Focus on Body Temperature; Sleep, Sleepiness, and Alcohol Use; Alcohol's Effect on Sleep in Alcoholics; Alcohol, Antidepressants, and Circadian Rhythms: Human and An...

D. M. Welsh

2001-01-01

46

[Influence of circadian rhythms on myocardial infarction].  

PubMed

Myocardial infarction is one of the most important causes of mortality and its incidence exhibits a significant circadian pattern with a peak of maximum frequency between 10 am and 11 am. Furthermore, myocardial infarction size and related mortality rate also undergo a variation over 24 hours. Recent publications have shown greatest myocardial injury when symptoms onsets are around midnight and this was independent of ischemic time and quality of care. These data were corroborated by studies using experimental models that unravel correlation between myocardial infarction's size and genes involved in circadian rhythm the link between circadian biology and pathophysiology of ischemia provides a new era of cardiovascular research and in addition new potential therapeutic targets to prevent myocardial ischemic burden. PMID:24964530

Fournier, S; Beggah, A T; Cook, S; Muller, O

2014-05-28

47

Circadian rhythms influence hematopoietic stem cells  

PubMed Central

Purpose of review Hematopoiesis is tightly regulated in the bone marrow (BM) through the microenvironment, soluble factors from the circulation and neural inputs from the autonomic nervous system. Most physiological processes are not uniform but rather vary according to the time of day. There is increasing evidence showing the impact of biological rhythms in the traffic of hematopoietic stem cells (HSC) and their proliferation and differentiation capacities. Recent findings Recent evidence supports the role of the sympathetic nervous system (SNS) in the regulation of HSC behavior, both directly and through supporting stromal cells. In addition, the SNS transduces circadian information from the central pacemaker in the brain, the suprachiasmatic nucleus (SCN), to the BM microenvironment, directing circadian oscillations in hematopoiesis and HSC migration. Summary HSC traffic and hematopoiesis do not escape the circadian regulation that control most physiological processes. Clinically, the timing of stem cell harvest or infusion may impact the yield or engraftment, respectively, and may result in better therapeutic outcomes.

Mendez-Ferrer, Simon; Chow, Andrew; Merad, Miriam; Frenette, Paul S.

2014-01-01

48

Circadian rhythms in lizards: phase response curve for melatonin.  

PubMed

Single biweekly injections of melatonin were administered to lizards (Sceloporus occidentalis) free-running (exhibiting their endogenous circadian activity rhythm) in constant dim illumination. The injections caused phase shifts in the activity rhythm whose magnitude and direction were a function of the time of the melatonin injections, relative to activity onsets. Plotting the direction and amount of phase shift versus the time (phase) at which the injection was given generates a phase-response curve (PRC). The PRC shows that injections administered between midsubjective day and early subjective night (6-15 hr after activity onset) elicit phase advances in the activity rhythm, whereas injections given at other phases of the activity cycle induce phase delays. The existence of a PRC for melatonin suggests that the daily endogenous rhythm of melatonin (i.e., of pineal origin) may be involved in phasing, or entraining, the circadian system of lizards. The shape of the PRC also allows predictions as to the effects of continuous exogenous melatonin administration on the period of free-running activity rhythms as well as on the mechanism of entrainment of activity rhythms to daily melatonin injections. PMID:3723331

Underwood, H

1986-01-01

49

Circadian Rhythm of Anaerobiosis in a Polychaete Annelid.  

National Technical Information Service (NTIS)

The report describes a rhythm of alternating aerobic and anaerobic metabolism in the polychaete Nereis virens. The rhythm is circadian under low intensity constant illumination. Burrows of N. virens are ventilated with undulatory movements of the body whi...

D. M. Scott

1976-01-01

50

N-nitrosomelatonin enhances photic synchronization of mammalian circadian rhythms.  

PubMed

Most physiological processes in mammals are synchronized to the daily light:dark cycle by a circadian clock located in the hypothalamic suprachiasmatic nucleus. Signal transduction of light-induced phase advances of the clock is mediated through a neuronal nitric oxide synthase-guanilyl cyclase pathway. We have employed a novel nitric oxide-donor, N-nitrosomelatonin, to enhance the photic synchronization of circadian rhythms in hamsters. The intraperitoneal administration of this drug before a sub-saturating light pulse at circadian time 18 generated a twofold increase of locomotor rhythm phase-advances, having no effect over saturating light pulses. This potentiation was also obtained even when inhibiting suprachiasmatic nitric oxide synthase activity. However, N-nitrosomelatonin had no effect on light-induced phase delays at circadian time 14. The photic-enhancing effects were correlated with an increased suprachiasmatic immunoreactivity of FBJ murine osteosarcoma viral oncogene and period1. Moreover, in vivo nitric oxide release by N-nitrosomelatonin was verified by measuring nitrate and nitrite levels in suprachiasmatic nuclei homogenates. The compound also accelerated resynchronization to an abrupt 6-h advance in the light:dark cycle (but not resynchronization to a 6-h delay). Here, we demonstrate the chronobiotic properties of N-nitrosomelatonin, emphasizing the importance of nitric oxide-mediated transduction for circadian phase advances. PMID:24261470

Baidanoff, Fernando M; Plano, Santiago A; Doctorovich, Fabio; Suárez, Sebastián A; Golombek, Diego A; Chiesa, Juan J

2014-04-01

51

Circadian Rhythms in the Mouse: A Connections Map  

NSDL National Science Digital Library

Genetic and biochemical experiments over the past decade have facilitated the construction of a viable working model for the molecular mechanisms that generate the circadian rhythm in Mus musculus. The basic mechanism consists of two intertwined transcription-translation negative feedback loops. One, the "positive loop," controls the rhythmic expression of a Per-Arnt-Sim (PAS)-domain-containing positive transcription factor, BMAL1 (also called MOP3). The other, the "negative loop," controls the transcription of mPeriod 1 and 2 and mCryptochrome 1 and 2, two families of genes that encode repressor proteins. The loops are intertwined because the proteins mPeriod and mCryptochrome directly repress transcription mediated by the CLOCK:BMAL1 heterodimer, whereas CLOCK:BMAL1 drives transcription of the mPeriod and mCryptochrome genes, as well as that of Rev-erb-alpha, a repressor of Bmal1 expression. Mutations, including the tau mutation in hamsters [encoding Casein kinase I ε (CkIε)], have identified essential functions for other proteins in the timekeeping mechanism. The master pacemaker for circadian rhythms in mice is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Light cycles can synchronize molecular rhythms in the SCN by stimulating the release of glutamate and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) from melanopsin-containing retinal ganglion cells. This results in increased transcription of mPeriod genes and a shift in the phase of the clock. This Pathway Map of the murine circadian mechanism describes the individual known components of the mouse circadian clock and their mutual interactions. Science Viewpoint R. N. Van Gelder, E. D. Herzog, W. J. Schwartz, P. H. Taghert, Circadian rhythms: In the loop at last. Science 300, 1534-1535 (2003). [Abstract] [Full Text

Russell N. Van Gelder (Washington University Medical School;Department of Molecular Biology and Pharmacology REV)

2003-08-05

52

A Missense Variation in Human Casein Kinase I Epsilon Gene that Induces Functional Alteration and Shows an Inverse Association with Circadian Rhythm Sleep Disorders  

Microsoft Academic Search

Recent studies have shown that functional variations in clock genes, which generate circadian rhythms through interactive positive\\/negative feedback loops, contribute to the development of circadian rhythm sleep disorders in humans. Another potential candidate for rhythm disorder susceptibility is casein kinase I epsilon (CKI?), which phosphorylates clock proteins and plays a pivotal role in the circadian clock. To determine whether variations

Atsuko Takano; Makoto Uchiyama; Naofumi Kajimura; Kazuo Mishima; Yuichi Inoue; Yuichi Kamei; Tsuyoshi Kitajima; Kayo Shibui; Masaaki Katoh; Tsuyoshi Watanabe; Yuki Hashimotodani; Toru Nakajima; Yuji Ozeki; Toru Hori; Naoto Yamada; Ryoichi Toyoshima; Norio Ozaki; Masako Okawa; Katsuya Nagai; Kiyohisa Takahashi; Yasushi Isojima; Toshio Yamauchi; Takashi Ebisawa

2004-01-01

53

Etiology and treatment of intrinsic circadian rhythm sleep disorders  

Microsoft Academic Search

Some individuals experience an acute or chronic sleep disturbance, associated with a misalignment between the timing of their sleep and the sleep-wake cycle that is desired, or considered normal by society. It is estimated that 5–10% of insomniacs seeking treatment have this type of disorder, collectively called circadian rhythm sleep disorders. This paper reviews circadian rhythm sleep disorders of the

Scott S. Campbell; Patricia J. Murphy; Cameron J. van den Heuvel; Melanie L. Roberts; Thomas N. Stauble

1999-01-01

54

Sildenafil accelerates reentrainment of circadian rhythms after advancing light schedules  

PubMed Central

Mammalian circadian rhythms are generated by a master clock located in the suprachiasmatic nuclei and entrained by light-activated signaling pathways. In hamsters, the mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase, cGMP and its related kinase (PKG). It is not completely known whether interference with this pathway affects entrainment of the clock, including adaptation to changing light schedules. Here we report that cGMP-specific phosphodiesterase 5 is present in the hamster suprachiasmatic nuclei, and administration of the inhibitor sildenafil (3.5 mg/kg, i.p.) enhances circadian responses to light and decreases the amount of time necessary for reentrainment after phase advances of the light–dark cycle. These results suggest that sildenafil may be useful for treatment of circadian adaptation to environmental changes, including transmeridian eastbound flight schedules.

Agostino, Patricia V.; Plano, Santiago A.; Golombek, Diego A.

2007-01-01

55

[Circadian rhythm and inflammatory bowel disease].  

PubMed

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a chronic and recurrent inflammatory disorder of the intestinal tract. It has been demonstrated that sleep disturbances are involved in the pathogenesis of the patients with IBD. In addition, it has been shown that melatonin, which is a hormone produced by the pineal gland and maintains circadian rhythm, plays an important role as regulators of inflammation as well as a player in proper immune system and antioxidant system in the intestinal disorders. In this review, we present what is currently known regarding sleep disturbances and the role of melatonin in intestinal inflammation. PMID:24437273

Takagi, Tomohisa; Inada, Yutaka; Naito, Yuji

2013-12-01

56

[Circadian rhythm disruption and human development].  

PubMed

Ontogenetic developments of rest-activity, sleep-wakefulness, temperature and several hormone rhythms in humans were reviewed. The reported effects of environment on these alterations were also summarized. Then, disorders or conditions which often encounter during early stage of life and reveal circadian rhythm disruptions were described. These disorders or conditions included severe brain damage, visual disturbance, developmental disorders(autistic spectrum disorder and attention deficit/hyperactivity disorder), Rett syndrome, Angelman syndrome, Smith-Magenis syndrome, epilepsy, Yonaki, and inadequate sleep hygiene. Finally, it was emphasized that we should pay special attention on the development of youngsters who showed sleep disturbance during early stage of life with special reference to the later occurrence of developmental disorders. PMID:24437259

Kohyama, Jun

2013-12-01

57

Treatment of Circadian Rhythm Sleep Disorders with Light  

Microsoft Academic Search

The human circadian system is normally synchronised with the solar day, insuring that alertness and performance peak during daytime hours and consolidated sleep occurs during the night. In circadian rhythm sleep disorders, the pattern of sleep-wake is misaligned with the patient's circadian system or the external environment, resulting in insomnia, fatigue, and deterioration in performance. Appropriately-timed exposure to bright light

Joshua J Gooley

2008-01-01

58

Circadian Rhythms, Aging, and Life Span in Mammals  

NSDL National Science Digital Library

Resetting the circadian clock leads to well being and increased life span, whereas clock disruption is associated with aging and morbidity. Increased longevity and improved health can be achieved by different feeding regimens that reset circadian rhythms and may lead to better synchrony in metabolism and physiology. This review focuses on recent findings concerning the relationships between circadian rhythms, aging attenuation, and life-span extension in mammals.

Oren Froy (The Hebrew University of Jerusalem Institute of Biochemistry, Food Science and Nutrition)

2011-08-01

59

Characterization of neurospora circadian rhythms in space  

NASA Technical Reports Server (NTRS)

To determine whether the circadian rhythm of conidiation in neurospora crassa is endogenously derived or is driven by some geophysical time cue, an experiment was conducted on space shuttle flight STS-9, where inoculated race tubes were exposed to the microgravity environment of space. The results demonstated that the rhythm can persist in space. However, there were several minor alterations noted; an increase in the period of the oscillation and the variability of the growth rate and a diminished rhythm amplitude, which eventually damped out in 25% of the flight tubes. On day seven of the flight, the tubes were exposed to light while their growth fronts were marked. It appears that some aspects of this marking process reinstated a robust rhythm in all the tubes which continued throughout the remainder of the flight. It was hypothesized that the damping found prior to the marking procedure on STS-9 may have been a result of the hypergravity pulse of launch and not due to the microgravity of the orbital lab; furthermore, that the marking procedure, by exposing the samples to light, had reinstated rhythmicity. To test this, an investigation was conducted into the effects of acute and chronic exposure to hypergravity.

Ferraro, James S.

1987-01-01

60

Circadian temperature rhythms of older people  

NASA Technical Reports Server (NTRS)

This collection of studies had the aim of exploring whether older (77+ years) men and women have circadian body temperature rhythms different from those of younger adults. A total of 20 older men and 28 older women were compared with either 22 young men or 14 middle-aged men in four protocols; all but the first protocol using a subset of the sample. The four protocols were: 1) 24 h, and 2) 72 h data collections on a normal laboratory routine (sleeping at night); 3) between 36 h and 153 h of field data collection at home; and 4) 36 h of a constant conditions routine (wakeful bedrest under temporal isolation) in the laboratory. There was some evidence for an age-related phase advance in temperature rhythm, especially for the older men on a normal routine, though this was not present in the constant conditions protocol, where 5 of the older subjects showed major delays in the timing of the body temperature trough (10:00 or later). There was no statistically significant evidence from any of the protocols that older subjects generally had lower temperature rhythm amplitudes than younger adults. Only when older men were compared with younger men in 24-h rhythm amplitude by simple t-test did any comparison involving amplitude achieve statistical significance (p < 0.05).

Monk, T. H.; Buysse, D. J.; Reynolds, C. F. 3rd; Kupfer, D. J.; Houck, P. R.

1995-01-01

61

Circadian Rhythm Sleep Disorder: Irregular Sleep Wake Rhythm Type  

PubMed Central

Irregular Sleep Wake Rhythm Disorder (ISWRD) is characterized by the relative absence of a circadian pattern in an individual’s sleep-wake cycle. Significant changes in circadian regulation occur with aging and with neurodegenerative diseases, such as Alzheimer’s disease prevalent in older adults, which are likely to contribute to the prevalence of ISWRD seen in these populations, although ISWRD is also seen in traumatic brain injury and mental retardation populations. ISWRD is thought to result from some combination of; degeneration or decreased neuronal activity of suprachiasmatic nucleus (SCN) neurons, decreased responsiveness of the circadian clock to entraining agents such as light and activity, and decreased exposure to bright light and structured social and physical activity during the day. Treatment of ISWRD seeks to consolidate sleep during the night and wakefulness during the day; primarily through restoring or enhancing exposure to the various SCN time cues, or “zeitgebers”. Studies of the effectiveness of pharmacologic treatments for ISWRD have generally yielded negative or inconsistent results. In general multi-modal non-pharmacological approaches involving increased exposure to light, increased physical and social activities and improved sleep hygiene have been the most successful therapeutic approaches.

Zee, Phyllis C.; Vitiello, Michael V.

2009-01-01

62

Relationships between the Circadian Rhythms of Finger Temperature, Core Temperature, Sleep Latency, and Subjective Sleepiness  

Microsoft Academic Search

Skin temperature circadian rhythms have been explored relatively recently. It has been suggested that distal and proximal skin temperature changes play a role in the regulation of the core temperature circadian rhythm and sleepiness. The authors investigated the circadian finger and core temperature rhythms in conjunction with the circadian rhythms of subjective and objective sleepiness. Fourteen healthy, young, good sleepers

Michael Gradisar; Leon Lack

2004-01-01

63

Robustness of circadian rhythms with respect to molecular noise  

NASA Astrophysics Data System (ADS)

We use a core molecular model capable of generating circadian rhythms to assess the robustness of circadian oscillations with respect to molecular noise. The model is based on the negative feedback exerted by a regulatory protein on the expression of its gene. Such a negative regulatory mechanism underlies circadian oscillations of the PER protein in Drosophila and of the FRQ protein in Neurospora. The model incorporates gene transcription into mRNA, translation of mRNA into protein, reversible phosphorylation leading to degradation of the regulatory protein, transport of the latter into the nucleus, and repression of gene expression by the nuclear form of the protein. To assess the effect of molecular noise, we perform stochastic simulations after decomposing the deterministic model into elementary reaction steps. The oscillations predicted by the stochastic simulations agree with those obtained with the deterministic version of the model. We show that robust circadian oscillations can occur already with a limited number of mRNA and protein molecules, in the range of tens and hundreds, respectively. Entrainment by light/dark cycles and cooperativity in repression enhance the robustness of circadian oscillations with respect to molecular noise.

Gonze, Didier; Halloy, José; Goldbeter, Albert

2002-01-01

64

RNAi of the circadian clock gene period disrupts the circadian rhythm but not the circatidal rhythm in the mangrove cricket  

PubMed Central

The clock mechanism for circatidal rhythm has long been controversial, and its molecular basis is completely unknown. The mangrove cricket, Apteronemobius asahinai, shows two rhythms simultaneously in its locomotor activity: a circatidal rhythm producing active and inactive phases as well as a circadian rhythm modifying the activity intensity of circatidal active phases. The role of the clock gene period (per), one of the key components of the circadian clock in insects, was investigated in the circadian and circatidal rhythms of A. asahinai using RNAi. After injection of double-stranded RNA of per, most crickets did not show the circadian modulation of activity but the circatidal rhythm persisted without a significant difference in the period from controls. Thus, per is functionally involved in the circadian rhythm but plays no role, or a less important role, in the circatidal rhythm. We conclude that the circatidal rhythm in A. asahinai is controlled by a circatidal clock whose molecular mechanism is different from that of the circadian clock.

Takekata, Hiroki; Matsuura, Yu; Goto, Shin G.; Satoh, Aya; Numata, Hideharu

2012-01-01

65

Circadian rhythms and addiction: mechanistic insights and future directions.  

PubMed

Circadian rhythms are prominent in many physiological and behavioral functions. Circadian disruptions either by environmental or molecular perturbation can have profound health consequences, including the development and progression of addiction. Both animal and humans studies indicate extensive bidirectional relationships between the circadian system and drugs of abuse. Addicted individuals display disrupted rhythms, and chronic disruption or particular chronotypes may increase the risk for substance abuse and relapse. Moreover, polymorphisms in circadian genes and an evening chronotype have been linked to mood and addiction disorders, and recent efforts suggest an association with the function of reward neurocircuitry. Animal studies are beginning to determine how altered circadian gene function results in drug-induced neuroplasticity and behaviors. Many studies suggest a critical role for circadian rhythms in reward-related pathways in the brain and indicate that drugs of abuse directly affect the central circadian pacemaker. In this review, we highlight key findings demonstrating the importance of circadian rhythms in addiction and how future studies will reveal important mechanistic insights into the involvement of circadian rhythms in drug addiction. PMID:24731209

Logan, Ryan W; Williams, Wilbur P; McClung, Colleen A

2014-06-01

66

Circadian rhythms in drosophila can be driven by period expression in a restricted group of central brain cells  

Microsoft Academic Search

Neural tissues controlling circadian rhythmicity have been identified in a variety of organisms and are often closely associated with the visual system. In Drosophila, the clock gene period (per), which is required for circadian rhythms, is expressed in many neurons and glia throughout the eye and brain. We asked whether biological rhythms could be generated if per expression were restricted

Leslie B. Vosshall; Michael W. Young

1995-01-01

67

Circadian locomotor rhythms in the cricket, Gryllodes sigillatus. II. Interactions between bilaterally paired circadian pacemakers.  

PubMed

The optic lobe is essential for circadian locomotor rhythms in the cricket, Gryllodes sigillatus. We examined potential interactions between the bilaterally paired optic lobes in circadian rhythm generation. When one optic lobe was removed, the free-running period of the locomotor rhythm slightly but significantly lengthened. When exposed to light-dark cycles (LD) with 26 hr period, intact and sham operated animals were clearly entrained to the light cycle, but a large number of animals receiving unilateral optic nerve severance showed rhythm dissociation. In the dissociation, two rhythmic components appeared; one was readily entrained to the given LD and the other free-ran with a period shorter than 24 hr, and activity was expressed only when they were inphase. The period of the free-running component was significantly longer than that of the animals with a single blinded pacemaker kept in LD13:13, suggesting that the pacemaker on the intact side had some influence on the blinded pacemaker even in the dissociated state. The ratio of animals with rhythm dissociation was greater with the lower light intensity of the LD. The results suggest that the bilaterally distributed pacemakers are only weakly coupled to one another but strongly suppress the activity driven by the partner pacemaker during their subjective day. The strong suppression of activity would be advantageous to keep a stable nocturnality for this cricket living indoors. PMID:9450386

Ushirogawa, H; Abe, Y; Tomioka, K

1997-10-01

68

Activity in the ferret: oestradiol effects and circadian rhythms  

NASA Technical Reports Server (NTRS)

The present study was conducted to determine whether oestradiol increases activity in the European ferret (Mustela furo), whether this effect is sexually dimorphic, and whether a 24-h rhythm is present in the ferret's daily activity. The activity of male and female adult, postpubertally gonadectomized ferrets was monitored while they were maintained singly on a 13:11 light-dark cycle, before and after implantation with oestradiol-17 beta. Gonadectomized male and female ferrets exhibited equal levels of activity, and neither sex exhibited a significant change in activity following oestradiol implantation. None of the ferrets exhibited a strong circadian rhythm, although weak 24-h rhythms and shorter harmonic rhythms were present. Golden hamsters (Mesocricetus auratus), monitored in an identical manner, exhibited strong circadian rhythms. It was concluded that oestradiol administration may not cause an increase in activity in the ferret, and that this species lacks a strong circadian activity rhythm.

Stockman, E. R.; Albers, H. E.; Baum, M. J.; Wurtman, R. J. (Principal Investigator)

1985-01-01

69

Effects of exercise on circadian rhythms and mobility in aging Drosophila melanogaster  

PubMed Central

Daily life functions such as sleep and feeding oscillate with circa 24 h period due to endogenous circadian rhythms generated by circadian clocks. Genetic or environmental disruption of circadian rhythms is associated with various aging-related phenotypes. Circadian rhythms decay during normal aging, and there is a need to explore strategies that could avert age-related changes in the circadian system. Exercise was reported to delay aging in mammals. Here, we investigated whether daily exercise via stimulation of upward climbing movement could improve circadian rest/activity rhythms in aging Drosophila melanogaster. We found that repeated exercise regimen did not strengthen circadian locomotor activity rhythms in aging flies and had no effect on their lifespan. We also tested the effects of exercise on mobility and determined that regular exercise lowered age-specific climbing ability in both wild type and clock mutant flies. Interestingly, the climbing ability was most significantly reduced in flies carrying a null mutation in the core clock gene period, while rescue of this gene significantly improved climbing to wild type levels. Our work highlights the importance of period in sustaining endurance in aging flies exposed to physical challenge.

Rakshit, Kuntol; Wambua, Rebecca; Giebultowicz, Tomasz M.; Giebultowicz, Jadwiga M.

2013-01-01

70

Synergistic interactions between the molecular and neuronal circadian networks drive robust behavioral circadian rhythms in Drosophila melanogaster.  

PubMed

Most organisms use 24-hr circadian clocks to keep temporal order and anticipate daily environmental changes. In Drosophila melanogaster CLOCK (CLK) and CYCLE (CYC) initiates the circadian system by promoting rhythmic transcription of hundreds of genes. However, it is still not clear whether high amplitude transcriptional oscillations are essential for circadian timekeeping. In order to address this issue, we generated flies in which the amplitude of CLK-driven transcription can be reduced partially (approx. 60%) or strongly (90%) without affecting the average levels of CLK-target genes. The impaired transcriptional oscillations lead to low amplitude protein oscillations that were not sufficient to drive outputs of peripheral oscillators. However, circadian rhythms in locomotor activity were resistant to partial reduction in transcriptional and protein oscillations. We found that the resilience of the brain oscillator is depending on the neuronal communication among circadian neurons in the brain. Indeed, the capacity of the brain oscillator to overcome low amplitude transcriptional oscillations depends on the action of the neuropeptide PDF and on the pdf-expressing cells having equal or higher amplitude of molecular rhythms than the rest of the circadian neuronal groups in the fly brain. Therefore, our work reveals the importance of high amplitude transcriptional oscillations for cell-autonomous circadian timekeeping. Moreover, we demonstrate that the circadian neuronal network is an essential buffering system that protects against changes in circadian transcription in the brain. PMID:24698952

Weiss, Ron; Bartok, Osnat; Mezan, Shaul; Malka, Yuval; Kadener, Sebastian

2014-04-01

71

Circadian rhythms in insect disease vectors  

PubMed Central

Organisms from bacteria to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation. This strong selection pressure has generated endogenous circadian clocks that regulate many aspects of behaviour, physiology and metabolism, anticipating and synchronising internal time-keeping to changes in the cyclical environment. In haematophagous insect vectors the circadian clock coordinates feeding activity, which is important for the dynamics of pathogen transmission. We have recently witnessed a substantial advance in molecular studies of circadian clocks in insect vector species that has consolidated behavioural data collected over many years, which provided insights into the regulation of the clock in the wild. Next generation sequencing technologies will facilitate the study of vector genomes/transcriptomes both among and within species and illuminate some of the species-specific patterns of adaptive circadian phenotypes that are observed in the field and in the laboratory. In this review we will explore these recent findings and attempt to identify potential areas for further investigation.

Meireles-Filho, Antonio Carlos Alves; Kyriacou, Charalambos Panayiotis

2013-01-01

72

Circadian rhythms and period expression in the Hawaiian cricket genus Laupala  

PubMed Central

Daily activity times and circadian rhythms of crickets have been a subject of behavioral and physiological study for decades. However, recent studies suggest that the underlying molecular mechanism of cricket endogenous clocks differ from the model of circadian rhythm generation in Drosophila. Here we examine the circadian free-running periods of walking and singing in two Hawaiian swordtail cricket species, Laupala cerasina and Laupala paranigra, that differ in the daily timing of mating related activities. Additionally, we examine variation in sequence and daily cycling of the period (per) gene transcript between these species. The species differed significantly in free-running period of singing, but did not differ significantly in the free-running period of locomotion. Like in Drosophila, per transcript abundance showed cycling consistent with a role in circadian rhythm generation. The amino acid differences identified between these species suggest a potential of the per gene in interspecific behavioral variation in Laupala.

Fergus, Daniel J.; Shaw, Kerry L.

2013-01-01

73

Olfactory bulb neurons express functional, entrainable circadian rhythms  

PubMed Central

Circadian pacemakers drive many daily molecular, physiological, and behavioral rhythms. We investigated whether the main olfactory bulb is a functional circadian pacemaker in rats. Long-term, multielectrode recordings revealed that individual, cultured bulb neurons expressed near 24-h oscillations in firing rate. Real-time recordings of Period1 gene activity showed that a population of cells within the bulb express synchronized rhythmicity starting on embryonic day 19. This rhythmicity was intrinsic to the mitral, and not the granule, cell layer, entrainable to physiological temperature cycles, and temperature compensated in its period. However, removal of the olfactory bulbs had no effect on running wheel behavior. These results indicate that individual mitral/tufted cells are competent circadian pacemakers which normally synchronize to each other. The daily rhythms in gene expression and firing rate intrinsic to the olfactory bulb are not required for circadian patterns of locomotion, indicating that they are involved in rhythms outside the canonical circadian system.

Granados-Fuentes, Daniel; Saxena, Meera T.; Prolo, Laura M.; Aton, Sara J.; Herzog, Erik D.

2012-01-01

74

Circadian rhythm dysfunction in glaucoma: A hypothesis  

Microsoft Academic Search

The absence of circadian zeitgebers in the social environment causes circadian misalignment, which is often associated with sleep disturbances. Circadian misalignment, defined as a mismatch between the sleep-wake cycle and the timing of the circadian system, can occur either because of inadequate exposure to the light-dark cycle, the most important synchronizer of the circadian system, or reduction in light transmission

Girardin Jean-Louis; Ferdinand Zizi; Douglas R Lazzaro; Arthur H Wolintz

2008-01-01

75

Melatonin, The Pineal Gland and Circadian Rhythms.  

National Technical Information Service (NTIS)

Amniote circadian organization derives from the interaction circadian oscillator and photoreceptors located in the hypothalamic suprachiasmatic nuclei (SCN), the pineal gland and the eyes. In mammals, circadian organization is dominated by the SCN which s...

V. M. Cassone

1992-01-01

76

Melatonin, the Pineal Gland, and Circadian Rhythms.  

National Technical Information Service (NTIS)

Amniote circadian organization derives from the interactions of circadian oscillator and photoreceptors located in the hypothalamic suprachiasmatic nuclei (SCN), the pineal gland, and the eyes. In mammals, circadian organization is dominated by the SCN, w...

V. M. Cassone W. S. Warren D. S. Brooks J. Lu

1993-01-01

77

Circadian rhythms in mouse suprachiasmatic nucleus explants on multimicroelectrode plates  

Microsoft Academic Search

The suprachiasmatic nucleus (SCN) of the mammalian hypothalamus functions as a circadian pacemaker. This study used multimicroelectrode plates to measure extracellular action potential activity simultaneously from multiple sites within the cultured mouse SCN. Neurons within the isolated mouse SCN expressed a circadian rhythm in spontaneous firing rate for weeks in culture.

Erik D Herzog; Michael E Geusz; Sat Bir S Khalsa; Martin Straume; Gene D Block

1997-01-01

78

Circadian rhythms and the pharmacology of affective illness  

Microsoft Academic Search

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of

Wallace C. Duncan

1996-01-01

79

The relationship between nutrition and circadian rhythms in mammals  

Microsoft Academic Search

The master clock located in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus regulates circadian rhythms in mammals. The clock is an intracellular, transcriptional mechanism sharing the same molecular components in SCN neurons and in peripheral cells, such as the liver, intestine, and retina. The circadian clock controls food processing and energy homeostasis by regulating the expression and\\/or activity of

Oren Froy

2007-01-01

80

Knock, knock to reset the clock: mechanosensation and circadian rhythms.  

PubMed

Circadian clocks, which underlie the daily rhythms in virtually all organisms, are entrained by diurnal changes in light, temperature, nutrients, and even sound. Simoni et al. (2014) demonstrate that diurnal variation in mechanical vibrations can reset circadian clock phase, providing a potential mechanism for integrating diverse clock-entraining stimuli. PMID:24807220

van Alphen, Bart; Allada, Ravi

2014-05-01

81

A clinical approach to circadian rhythm sleep disorders  

Microsoft Academic Search

Circadian rhythm sleep disorders are characterized by complaints of insomnia and excessive sleepiness that are primarily due to alterations in the internal circadian timing system or a misalignment between the timing of sleep and the 24-h social and physical environment. In addition to physiological and environmental factors, maladaptive behaviors often play an important role in the development of many of

Ana Barion; Phyllis C. Zee

2007-01-01

82

Circadian Rhythm of Anaerobiosis in a Polychaete Annelid.  

National Technical Information Service (NTIS)

The rhythm of alternating aerobic and anaerobic metabolism in the polychaete Nereis virens is described. The rhythm is circadian under low intensity constant illumination. N. virens seems to cease burrow ventilation for periods of up to 9 h during which r...

D. M. Scott

1976-01-01

83

Pineal Photoreceptor Cells Are Required for Maintaining the Circadian Rhythms of Behavioral Visual Sensitivity in Zebrafish  

PubMed Central

In non-mammalian vertebrates, the pineal gland functions as the central pacemaker that regulates the circadian rhythms of animal behavior and physiology. We generated a transgenic zebrafish line [Tg(Gnat2:gal4-VP16/UAS:nfsB-mCherry)] in which the E. coli nitroreductase is expressed in pineal photoreceptor cells. In developing embryos and young adults, the transgene is expressed in both retinal and pineal photoreceptor cells. During aging, the expression of the transgene in retinal photoreceptor cells gradually diminishes. By 8 months of age, the Gnat2 promoter-driven nitroreductase is no longer expressed in retinal photoreceptor cells, but its expression in pineal photoreceptor cells persists. This provides a tool for selective ablation of pineal photoreceptor cells, i.e., by treatments with metronidazole. In the absence of pineal photoreceptor cells, the behavioral visual sensitivity of the fish remains unchanged; however, the circadian rhythms of rod and cone sensitivity are diminished. Brief light exposures restore the circadian rhythms of behavioral visual sensitivity. Together, the data suggest that retinal photoreceptor cells respond to environmental cues and are capable of entraining the circadian rhythms of visual sensitivity; however, they are insufficient for maintaining the rhythms. Cellular signals from the pineal photoreceptor cells may be required for maintaining the circadian rhythms of visual sensitivity.

Li, Xinle; Montgomery, Jake; Cheng, Wesley; Noh, Jung Hyun; Hyde, David R.; Li, Lei

2012-01-01

84

Fitness costs of disrupting circadian rhythms in malaria parasites  

PubMed Central

Circadian biology assumes that biological rhythms maximize fitness by enabling organisms to coordinate with their environment. Despite circadian clocks being such a widespread phenomenon, demonstrating the fitness benefits of temporal coordination is challenging and such studies are rare. Here, we tested the consequences—for parasites—of being temporally mismatched to host circadian rhythms using the rodent malaria parasite, Plasmodium chabaudi. The cyclical nature of malaria infections is well known, as the cell cycles across parasite species last a multiple of approximately 24 h, but the evolutionary explanations for periodicity are poorly understood. We demonstrate that perturbation of parasite rhythms results in a twofold cost to the production of replicating and transmission stages. Thus, synchronization with host rhythms influences in-host survival and between-host transmission potential, revealing a role for circadian rhythms in the evolution of host–parasite interactions. More generally, our results provide a demonstration of the adaptive value of circadian rhythms and the utility of using an evolutionary framework to understand parasite traits.

O'Donnell, Aidan J.; Schneider, Petra; McWatters, Harriet G.; Reece, Sarah E.

2011-01-01

85

Two circadian rhythms in the human electroencephalogram during wakefulness.  

PubMed

The influence of the circadian pacemaker and of the duration of time awake on the electroencephalogram (EEG) was investigated in 19 humans during approximately 40 h of sustained wakefulness. Two circadian rhythms in spectral power density were educed. The first rhythm was centered in the theta band (4.25-8.0 Hz) and exhibited a minimum approximately 1 h after the onset of melatonin secretion. The second rhythm was centered in the high-frequency alpha band (10.25-13.0 Hz) and exhibited a minimum close to the body temperature minimum. The latter rhythm showed a close temporal association with the rhythms in subjective alertness, plasma melatonin, and body temperature. In addition, increasing time awake was associated with an increase of power density in the 0.25- to 9.0-Hz and 13.25- to 20. 0-Hz ranges. It is concluded that the waking EEG undergoes changes that can be attributed to circadian and homeostatic (i.e., sleep-wake dependent) processes. The distinct circadian variations of EEG activity in the theta band and in the high-frequency alpha band may represent electrophysiological correlates of different aspects of the circadian rhythm in arousal. PMID:10600925

Aeschbach, D; Matthews, J R; Postolache, T T; Jackson, M A; Giesen, H A; Wehr, T A

1999-12-01

86

Circadian Stomatal Rhythms in Epidermal Peels from Vicia faba1  

PubMed Central

Circadian rhythms in stomatal aperture and in stomatal conductance have been observed previously. Here we investigate circadian rhythms in apertures that persist in functionally isolated guard cells in epidermal peels of Vicia faba, and we compare these rhythms with rhythms in stomatal conductance in attached leaves. Functionally isolated guard cells kept in constant light display a rhythmic change in aperture superimposed on a continuous opening trend. The rhythm free-runs with a period of about 22 hours and is temperature compensated between 20 and 30°C. Functionally isolated guard cell pairs are therefore capable of sustaining a true circadian rhythm without interaction with mesophyll cells. Stomatal conductance in whole leaves displays a more robust rhythm, also temperature-compensated, and with a period similar to that observed for the rhythm in stomatal aperture in epidermal peels. When analyzed individually, some stomata in epidermal peels showed a robust rhythm for several days while others showed little rhythmicity or damped out rapidly. Rhythmic periods may vary between individual stomata, and this may lead to desynchronization within the population.

Gorton, Holly L.; Williams, William E.; Binns, Mary Elizabeth; Gemmell, Craig N.; Leheny, Ellen A.; Shepherd, Andrew C.

1989-01-01

87

Regulation of circadian rhythms in mammals by behavioral arousal.  

PubMed

Circadian rhythms in most mammals are synchronized to local time by phase and period resetting actions of daily light-dark cycles on a retino-recipient, light-entrainable circadian pacemaker, the suprachiasmatic nucleus (SCN). The SCN receives input from other brain regions, some of which mediate the phase and period resetting actions of behavioral arousal on circadian rhythms. We review historical milestones in the discovery of so-called "nonphotic" circadian clock resetting induced by environmentally stimulated arousal, or by feedback from clock-controlled rest-activity cycles. Topics include species generality, interactions between concurrent or successive photic and nonphotic inputs to the circadian clock, neural pathways, neurotransmitters, and clock cell responses that mediate resetting by behavioral arousal. The role of behavioral inputs to the circadian clock in determining the phase of entrainment to local time in natural environments is not well understood. Nonetheless, nonphotic effects are of sufficient magnitude to raise issues for the design of experiments in behavioral neuroscience (any procedure that is sufficiently arousing may alter the timing of circadian clocks that regulate dependent variables of primary interest). Nonphotic inputs to the clock may be exploited in strategies to reset or strengthen circadian rhythms in humans. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24773430

Webb, Ian C; Antle, Michael C; Mistlberger, Ralph E

2014-06-01

88

Dopaminergic Regulation of Circadian Food Anticipatory Activity Rhythms in the Rat  

PubMed Central

Circadian activity rhythms are jointly controlled by a master pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) and by food-entrainable circadian oscillators (FEOs) located elsewhere. The SCN mediates synchrony to daily light-dark cycles, whereas FEOs generate activity rhythms synchronized with regular daily mealtimes. The location of FEOs generating food anticipation rhythms, and the pathways that entrain these FEOs, remain to be clarified. To gain insight into entrainment pathways, we developed a protocol for measuring phase shifts of anticipatory activity rhythms in response to pharmacological probes. We used this protocol to examine a role for dopamine signaling in the timing of circadian food anticipation. To generate a stable food anticipation rhythm, rats were fed 3h/day beginning 6-h after lights-on or in constant light for at least 3 weeks. Rats then received the D2 agonist quinpirole (1 mg/kg IP) alone or after pretreatment with the dopamine synthesis inhibitor ?-methylparatyrosine (AMPT). By comparison with vehicle injections, quinpirole administered 1-h before lights-off (19h before mealtime) induced a phase delay of activity onset prior to the next meal. Delay shifts were larger in rats pretreated with AMPT, and smaller following quinpirole administered 4-h after lights-on. A significant shift was not observed in response to the D1 agonist SKF81297. These results provide evidence that signaling at D2 receptors is involved in phase control of FEOs responsible for circadian food anticipatory rhythms in rats.

Smit, Andrea N.; Patton, Danica F.; Michalik, Mateusz; Opiol, Hanna; Mistlberger, Ralph E.

2013-01-01

89

Relationships Between Behavioral Rhythms, Plasma Corticosterone and Hypothalamic Circadian Rhythms.  

National Technical Information Service (NTIS)

Circadian rythms in physiological processes and behaviors were compared with hypothalamic circadian ryhthms in norepinephrine (NE) metabolites, adrenergic transmitter receptors, cAMP, cGMP and suprachiasmatic nucleus (SCN) arginine vasopressin (AVP) in a ...

M. S. Kafka M. A. Benedito L. K. Steele M. J. Gibson R. L. Zerbe

1986-01-01

90

Sleep, circadian rhythms, and psychomotor vigilance.  

PubMed

Psychomotor vigilance performance is highly relevant to athletic performance. It is influenced by a sleep homeostatic process, which builds up pressure for sleep during wakefulness and dissipates this pressure during sleep, and a circadian rhythm process, which produces a waxing and waning of pressure for wakefulness over a 24 hours of the day. During total sleep deprivation, these two processes cause performance to deteriorate progressively over days, modulated within days by further performance reductions at night and relative improvements during the daytime. As the homeostatic pressure for sleep builds up higher across prolonged wakefulness, the rate of dissipation of that pressure during subsequent sleep is enhanced exponentially, so that even brief periods of sleep provide significant performance recuperation. Nevertheless, sleep restriction practiced on a chronic basis induces cumulative performance deficits of the same order of magnitude as observed during total sleep deprivation. There are also considerable individual differences in the degree of vulnerability to performance impairment from sleep loss, and these differences represent a trait. PMID:15892921

Van Dongen, Hans P A; Dinges, David F

2005-04-01

91

Circadian temperature rhythm blunting and sleep composition.  

PubMed

The sleep patterns of nine male subjects were studied on four consecutive nights comprising two baseline nights, one night on which environmental temperature was elevated from 21 degrees C to 30 degrees C one hour after lights out, and a recovery night. There was a suppression of stage 4 sleep during the initial three hours of sleep on the hot night. A significant increase in stage 4 sleep with a decrease in stage 2 sleep occurred during the first three hours of the recovery sleep. There was a shortening in sleep onset latency and an increase in sleep efficiency on the recovery night. There were no changes in REM latency or REM sleep time. Rectal temperature rose after the increase in ambient temperature on the hot night. These results indicate that elevations in environmental temperature during sleep affect sleep patterns in a manner opposite to elevations of body temperature occurring prior to sleep onset. The curtailing of the usual circadian temperature drop during the first few hours of sleep reduces slow-wave sleep during this period. These findings have implications for those conditions with both altered sleep and altered temperature rhythms, for example, depression. PMID:3245467

Bonegio, R G; Driver, H S; King, L M; Laburn, H P; Shapiro, C M

1988-01-01

92

Circadian rhythm in serum iron levels.  

PubMed

This study was aimed at assessing the circadian rhythm of serum iron levels in Chinese healthy subjects. The project was conducted in 19 healthy, Chinese male subjects following a 4-day diet equilibration. Blood samples were collected on day 5 at 0800, 1000, 1200, 1400, 1600, 1800, 2000, and 2400 hours to determine endogenous serum iron concentrations. Iron concentrations were determined using an inductively coupled plasma mass spectrometry. Iron concentration was decreased from morning to afternoon. The minimum value of iron level was 1,987 ?g/L at 2000 hours while the maximum was 2,229 ?g/L at 1000 hours, and 2,278 ?g/L at 1400 hours, respectively, the amplitude was 291 ?g/L. This study indicates that when assessing the bioequivalence of iron formulations, baseline levels of iron (obtained before dosing) should not be subtracted simply from the amount obtained on the drug dosing day to yield the net effect of iron formulation administration. More valid methods to optimize the design of such bioequivalence studies should be taken into consideration. PMID:22198869

Cao, Guo Ying; Li, Yang; Jin, Peng Fei; Hu, Xin

2012-06-01

93

Melatonin, the Pineal Gland and Circadian Rhythms.  

National Technical Information Service (NTIS)

The rat pineal is a component of the circadian clock. Exogenous melatonin entrains the rat clock and does not require the presence of the pineal gland. The pineal gland is important for circadian rhythmicity. Pinealectomy exacerbates the disruptive effect...

V. M. Cassone

1995-01-01

94

Circadian Rhythm Connections to Oxidative Stress: Implications for Human Health  

PubMed Central

Abstract Significance: Oxygen and circadian rhythmicity are essential in a myriad of physiological processes to maintain homeostasis, from blood pressure and sleep/wake cycles, down to cellular signaling pathways that play critical roles in health and disease. If the human body or cells experience significant stress, their ability to regulate internal systems, including redox levels and circadian rhythms, may become impaired. At cellular as well as organismal levels, impairment in redox regulation and circadian rhythms may lead to a number of adverse effects, including the manifestation of a variety of diseases such as heart diseases, neurodegenerative conditions, and cancer. Recent Advances: Researchers have come to an understanding as to the basics of the circadian rhythm mechanism, as well as the importance of the numerous species of oxidative stress components. The effects of oxidative stress and dysregulated circadian rhythms have been a subject of intense investigations since they were first discovered, and recent investigations into the molecular mechanisms linking the two have started to elucidate the bases of their connection. Critical Issues: While much is known about the mechanics and importance of oxidative stress systems and circadian rhythms, the front where they interact has had very little research focused on it. This review discusses the idea that these two systems are together intricately involved in the healthy body, as well as in disease. Future Directions: We believe that for a more efficacious management of diseases that have both circadian rhythm and oxidative stress components in their pathogenesis, targeting both systems in tandem would be far more successful. Antioxid. Redox Signal. 19, 192–208

Wilking, Melissa; Ndiaye, Mary; Mukhtar, Hasan

2013-01-01

95

Cell-autonomous circadian clock of hepatocytes drives rhythms in transcription and polyamine synthesis  

PubMed Central

The circadian clock generates daily rhythms in mammalian liver processes, such as glucose and lipid homeostasis, xenobiotic metabolism, and regeneration. The mechanisms governing these rhythms are not well understood, particularly the distinct contributions of the cell-autonomous clock and central pacemaker to rhythmic liver physiology. Through microarray expression profiling in Met murine hepatocytes (MMH)-D3, we identified over 1,000 transcripts that exhibit circadian oscillations, demonstrating that the cell-autonomous clock can drive many rhythms, and that MMH-D3 is a valid circadian model system. The genes represented by these circadian transcripts displayed both cophasic and antiphasic organization within a protein–protein interaction network, suggesting the existence of competition for binding sites or partners by genes of disparate transcriptional phases. Multiple pathways displayed enrichment in MMH-D3 circadian transcripts, including the polyamine synthesis module of the glutathione metabolic pathway. The polyamine synthesis module, which is highly associated with cell proliferation and whose products are required for initiation of liver regeneration, includes enzymes whose transcripts exhibit circadian oscillations, such as ornithine decarboxylase and spermidine synthase. Metabolic profiling revealed that the enzymatic product of spermidine synthase, spermidine, cycles as well. Thus, the cell-autonomous hepatocyte clock can drive a significant amount of transcriptional rhythms and orchestrate physiologically relevant modules such as polyamine synthesis.

Atwood, Ann; DeConde, Robert; Wang, Susanna S.; Mockler, Todd C.; Sabir, Jamal S. M.; Ideker, Trey; Kay, Steve A.

2011-01-01

96

Circadian Rhythms of Ethylene Emission in Arabidopsis1[w  

PubMed Central

Ethylene controls multiple physiological processes in plants, including cell elongation. Consequently, ethylene synthesis is regulated by internal and external signals. We show that a light-entrained circadian clock regulates ethylene release from unstressed, wild-type Arabidopsis (Arabidopsis thaliana) seedlings, with a peak in the mid-subjective day. The circadian clock drives the expression of multiple ACC SYNTHASE genes, resulting in peak RNA levels at the phase of maximal ethylene synthesis. Ethylene production levels are tightly correlated with ACC SYNTHASE 8 steady-state transcript levels. The expression of this gene is controlled by light, by the circadian clock, and by negative feedback regulation through ethylene signaling. In addition, ethylene production is controlled by the TIMING OF CAB EXPRESSION 1 and CIRCADIAN CLOCK ASSOCIATED 1 genes, which are critical for all circadian rhythms yet tested in Arabidopsis. Mutation of ethylene signaling pathways did not alter the phase or period of circadian rhythms. Mutants with altered ethylene production or signaling also retained normal rhythmicity of leaf movement. We conclude that circadian rhythms of ethylene production are not critical for rhythmic growth.

Thain, Simon C.; Vandenbussche, Filip; Laarhoven, Lucas J.J.; Dowson-Day, Mandy J.; Wang, Zhi-Yong; Tobin, Elaine M.; Harren, Frans J.M.; Millar, Andrew J.; Van Der Straeten, Dominique

2004-01-01

97

Circadian Rhythms in Stomatal Responsiveness to Red and Blue Light.  

PubMed Central

Stomata of many plants have circadian rhythms in responsiveness to environmental cues as well as circadian rhythms in aperture. Stomatal responses to red light and blue light are mediated by photosynthetic photoreceptors; responses to blue light are additionally controlled by a specific blue-light photoreceptor. This paper describes circadian rhythmic aspects of stomatal responsiveness to red and blue light in Vicia faba. Plants were exposed to a repeated light:dark regime of 1.5:2.5 h for a total of 48 h, and because the plants could not entrain to this short light:dark cycle, circadian rhythms were able to "free run" as if in continuous light. The rhythm in the stomatal conductance established during the 1.5-h light periods was caused both by a rhythm in sensitivity to light and by a rhythm in the stomatal conductance established during the preceding 2.5-h dark periods. Both rhythms peaked during the middle of the subjective day. Although the stomatal response to blue light is greater than the response to red light at all times of day, there was no discernible difference in period, phase, or amplitude of the rhythm in sensitivity to the two light qualities. We observed no circadian rhythmicity in net carbon assimilation with the 1.5:2.5 h light regime for either red or blue light. In continuous white light, small rhythmic changes in photosynthetic assimilation were observed, but at relatively high light levels, and these appeared to be attributable largely to changes in internal CO2 availability governed by stomatal conductance.

Gorton, H. L.; Williams, W. E.; Assmann, S. M.

1993-01-01

98

Circadian melatonin rhythm and excessive daytime sleepiness in Parkinson disease.  

PubMed

IMPORTANCE Diurnal fluctuations of motor and nonmotor symptoms and a high prevalence of sleep-wake disturbances in Parkinson disease (PD) suggest a role of the circadian system in the modulation of these symptoms. However, surprisingly little is known regarding circadian function in PD and whether circadian dysfunction is involved in the development of sleep-wake disturbances in PD. OBJECTIVE To determine the relationship between the timing and amplitude of the 24-hour melatonin rhythm, a marker of endogenous circadian rhythmicity, with self-reported sleep quality, the severity of daytime sleepiness, and disease metrics. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study from January 1, 2009, through December 31, 2012, of 20 patients with PD receiving stable dopaminergic therapy and 15 age-matched control participants. Both groups underwent blood sampling for the measurement of serum melatonin levels at 30-minute intervals for 24 hours under modified constant routine conditions at the Parkinson's Disease and Movement Disorders Center of Northwestern University. INTERVENTIONS Twenty-four hour monitoring of serum melatonin secretion. MAIN OUTCOMES AND MEASURES Clinical and demographic data, self-reported measures of sleep quality (Pittsburgh Sleep Quality Index) and daytime sleepiness (Epworth Sleepiness Scale), and circadian markers of the melatonin rhythm, including the amplitude, area under the curve (AUC), and phase of the 24-hour rhythm. RESULTS Patients with PD had blunted circadian rhythms of melatonin secretion compared with controls; the amplitude of the melatonin rhythm and the 24-hour AUC for circulating melatonin levels were significantly lower in PD patients (P?circadian phase were not significantly different between the 2 groups. Compared with PD patients without excessive daytime sleepiness, patients with excessive daytime sleepiness (Epworth Sleepiness Scale score ?10) had a significantly lower amplitude of the melatonin rhythm and 24-hour melatonin AUC (P?=?.001). Disease duration, Unified Parkinson's Disease Rating Scale scores, levodopa equivalent dose, and global Pittsburgh Sleep Quality Index score in the PD group were not significantly related to measures of the melatonin circadian rhythm. CONCLUSIONS AND RELEVANCE Circadian dysfunction may underlie excessive sleepiness in PD. The nature of this association needs to be explored further in longitudinal studies. Approaches aimed to strengthen circadian function, such as timed exposure to bright light and exercise, might serve as complementary therapies for the nonmotor manifestations of PD. PMID:24566763

Videnovic, Aleksandar; Noble, Charleston; Reid, Kathryn J; Peng, Jie; Turek, Fred W; Marconi, Angelica; Rademaker, Alfred W; Simuni, Tanya; Zadikoff, Cindy; Zee, Phyllis C

2014-04-01

99

Circadian melatonin rhythm and excessive daytime sleepiness in Parkinson's disease  

PubMed Central

Importance Diurnal fluctuations of motor and non-motor symptoms and high prevalence of sleep/wake disturbances in Parkinson’s disease (PD) suggest a role of the circadian system in the modulation of these symptoms. Yet, surprisingly little is known regarding circadian function in PD, and whether circadian dysfunction is involved in the development of sleep/wake disturbances in PD. Objective The objective of this study was to determine the relationship between the timing and amplitude of the 24-hour melatonin rhythm, a marker of endogenous circadian rhythmicity, with self-reported sleep quality, the severity of daytime sleepiness and disease metrics. Design A cross-sectional study, (2009–2012). Setting PD and Movement Disorders Center, Northwestern University, Chicago. Participants Twenty PD patients on stable dopaminergic therapy and 15 age-matched controls underwent blood sampling for the measurement of serum melatonin levels at 30-minute intervals for 24 hours under modified constant routine conditions. Main Outcome Measure(s) Clinical and demographic data, self-reported measures of sleep quality (Pittsburgh Sleep Quality Index (PSQI)) and daytime sleepiness (Epworth Sleepiness Scale (ESS)), circadian markers of the melatonin rhythm, including the amplitude, area-under-the-curve (AUC), and phase of the 24-hour rhythm. Results Participants with PD had a blunted circadian rhythms of melatonin secretion compared to controls; both the amplitude of the melatonin rhythm and the 24-hour AUC for circulating melatonin levels were significantly lower in PD participants compared with controls (p<0.001). Markers of circadian phase were not significantly different between the two groups. Among PD participants, those with excessive daytime sleepiness (ESS score ?10) had a significantly lower amplitude of the melatonin rhythm and the 24-hour melatonin AUC compared with PD participants without excessive sleepiness (p=0.001). Disease duration, UPDRS scores, levodopa equivalent dose and global PSQI scores in the PD group were not significantly related to measures of the melatonin circadian rhythm. Conclusion and Relevance These results indicate that circadian dysfunction may underlie excessive sleepiness in PD. The nature of this association needs to be further explored in longitudinal studies. Approaches aimed to strengthen circadian function, such as timed bright light and exercise, might potentially serve as complementary therapies for the non-motor manifestations of PD.

Videnovic, Aleksandar; Noble, Charleston; Reid, Kathryn J.; Peng, Jie; Turek, Fred W.; Marconi, Angelica; Rademaker, Alfred W.; Simuni, Tanya; Zadikoff, Cindy; Zee, Phyllis C.

2014-01-01

100

Circadian Genes, Rhythms and the Biology of Mood Disorders  

PubMed Central

For many years, researchers have suggested that abnormalities in circadian rhythms may underlie the development of mood disorders such as bipolar disorder, major depression and seasonal affective disorder. Furthermore, some of the treatments that are currently employed to treat mood disorders are thought to act by shifting or “resetting” the circadian clock, including total sleep deprivation and bright light therapy. There is also reason to suspect that many of the mood stabilizers and antidepressants used to treat these disorders may derive at least some of their therapeutic efficacy by affecting the circadian clock. Recent genetic, molecular and behavioral studies implicate individual genes that make up the clock in mood regulation. As well, important functions of these genes in brain regions and neurotransmitter systems associated with mood regulation is becoming apparent. In this review, the evidence linking circadian rhythms and mood disorders, and what is known about the underlying biology of this association, is presented.

McClung, Colleen A.

2007-01-01

101

Light as a central modulator of circadian rhythms, sleep and affect.  

PubMed

Light has profoundly influenced the evolution of life on earth. As widely appreciated, light enables us to generate images of our environment. However, light - through intrinsically photosensitive retinal ganglion cells (ipRGCs) - also influences behaviours that are essential for our health and quality of life but are independent of image formation. These include the synchronization of the circadian clock to the solar day, tracking of seasonal changes and the regulation of sleep. Irregular light environments lead to problems in circadian rhythms and sleep, which eventually cause mood and learning deficits. Recently, it was found that irregular light can also directly affect mood and learning without producing major disruptions in circadian rhythms and sleep. In this Review, we discuss the indirect and direct influence of light on mood and learning, and provide a model for how light, the circadian clock and sleep interact to influence mood and cognitive functions. PMID:24917305

LeGates, Tara A; Fernandez, Diego C; Hattar, Samer

2014-07-01

102

A circadian rhythm sleep disorder: melatonin resets the biological clock.  

PubMed

Circadian rhythm sleep disorders are poorly understood and often misdiagnosed. They are all related to the timing of sleep within the 24-hour day. This paper describes a patient with a long history of sleep disturbance whom we diagnosed as having delayed sleep phase syndrome by history and measurement of urinary melatonin metabolite excretion. Literature on the characteristics, diagnosis and management of this syndrome are briefly reviewed. In addition, the relation of the neurohormone melatonin to circadian rhythm and its other physiological roles are described. PMID:21132137

Abbas, A; Raju, J; Milles, J; Ramachandran, S

2010-12-01

103

Minimum criteria for DNA damage-induced phase advances in circadian rhythms.  

PubMed

Robust oscillatory behaviors are common features of circadian and cell cycle rhythms. These cyclic processes, however, behave distinctively in terms of their periods and phases in response to external influences such as light, temperature, nutrients, etc. Nevertheless, several links have been found between these two oscillators. Cell division cycles gated by the circadian clock have been observed since the late 1950s. On the other hand, ionizing radiation (IR) treatments cause cells to undergo a DNA damage response, which leads to phase shifts (mostly advances) in circadian rhythms. Circadian gating of the cell cycle can be attributed to the cell cycle inhibitor kinase Wee1 (which is regulated by the heterodimeric circadian clock transcription factor, BMAL1/CLK), and possibly in conjunction with other cell cycle components that are known to be regulated by the circadian clock (i.e., c-Myc and cyclin D1). It has also been shown that DNA damage-induced activation of the cell cycle regulator, Chk2, leads to phosphorylation and destruction of a circadian clock component (i.e., PER1 in Mus or FRQ in Neurospora crassa). However, the molecular mechanism underlying how DNA damage causes predominantly phase advances in the circadian clock remains unknown. In order to address this question, we employ mathematical modeling to simulate different phase response curves (PRCs) from either dexamethasone (Dex) or IR treatment experiments. Dex is known to synchronize circadian rhythms in cell culture and may generate both phase advances and delays. We observe unique phase responses with minimum delays of the circadian clock upon DNA damage when two criteria are met: (1) existence of an autocatalytic positive feedback mechanism in addition to the time-delayed negative feedback loop in the clock system and (2) Chk2-dependent phosphorylation and degradation of PERs that are not bound to BMAL1/CLK. PMID:19424508

Hong, Christian I; Zámborszky, Judit; Csikász-Nagy, Attila

2009-05-01

104

Circadian rhythms of temperature and activity in obese and lean Zucker rats  

NASA Technical Reports Server (NTRS)

The circadian timing system is important in the regulation of feeding and metabolism, both of which are aberrant in the obese Zucker rat. This study tested the hypothesis that these abnormalities involve a deficit in circadian regulation by examining the circadian rhythms of body temperature and activity in lean and obese Zucker rats exposed to normal light-dark cycles, constant light, and constant dark. Significant deficits in both daily mean and circadian amplitude of temperature and activity were found in obese Zucker female rats relative to lean controls in all lighting conditions. However, the circadian period of obese Zucker rats did not exhibit differences relative to lean controls in either of the constant lighting conditions. These results indicate that although the circadian regulation of temperature and activity in obese Zucker female rats is in fact depressed, obese rats do exhibit normal entrainment and pacemaker functions in the circadian timing system. The results suggest a deficit in the process that generates the amplitude of the circadian rhythm.

Murakami, D. M.; Horwitz, B. A.; Fuller, C. A.

1995-01-01

105

Disrupted circadian rhythms in VIP and PHI-deficient mice  

Microsoft Academic Search

rhythms in VIP- and PHI-deficient mice. Am J Physiol Regul Integr Comp Physiol 285: R939-R949, 2003. First published July 10, 2003; 10.1152\\/ajpregu.00200.2003.—The related neuropeptides vasoactive intestinal peptide (VIP) and pep- tide histidine isoleucine (PHI) are expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN), but their function in the regulation of circadian rhythms is unknown. To study

Christopher S. Colwell; Stephan Michel; Jason Itri; Williams Rodriguez; J. Tam; Vincent Lelievre; Zhou Hu; X. Liu; James A. Waschek

106

Circadian Rhythms of Fetal Liver Transcription Persist in the Absence of Canonical Circadian Clock Gene Expression Rhythms In Vivo  

PubMed Central

The cellular circadian clock and systemic cues drive rhythmicity in the transcriptome of adult peripheral tissues. However, the oscillating status of the circadian clocks in fetal tissues, and their response to maternal cues, are less clear. Most clock genes do not cycle in fetal livers from mice and rats, although tissue level rhythms rapidly emerge when fetal mouse liver explants are cultured in vitro. Thus, in the fetal mouse liver, the circadian clock does not oscillate at the cellular level (but is induced to oscillate in culture). To gain a comprehensive overview of the clock status in the fetal liver during late gestation, we performed microarray analyses on fetal liver tissues. In the fetal liver we did not observe circadian rhythms of clock gene expression or many other transcripts known to be rhythmically expressed in the adult liver. Nevertheless, JTK_CYCLE analysis identified some transcripts in the fetal liver that were rhythmically expressed, albeit at low amplitudes. Upon data filtering by coefficient of variation, the expression levels for transcripts related to pancreatic exocrine enzymes and zymogen secretion were found to undergo synchronized daily fluctuations at high amplitudes. These results suggest that maternal cues influence the fetal liver, despite the fact that we did not detect circadian rhythms of canonical clock gene expression in the fetal liver. These results raise important questions on the role of the circadian clock, or lack thereof, during ontogeny.

Li, Chengwei; Yu, Shuang; Zhong, Xiaoling; Wu, Jianguo; Li, Xiaodong

2012-01-01

107

Circadian Rhythms: In the Loop at Last  

NSDL National Science Digital Library

This Viewpoint compares and contrasts the circadian clocks of mammals and of Drosophila, emphasizing how different players are used to create the same basic script. Both the general script and the specific details of the murine and Drosophila circadian pathways are available at Science's Signal Transduction Knowledge Environment Connections Maps.

Russell N. Van Gelder (Washington University;Department of Ophthalmology and Visual Sciences/Department of Molecular Biology and Pharmacology); Erik D. Herzog (Washington University;Department of Biology); William Schwartz (University of Massachusetts Medical School;Department of Neurology); Paul Taghert (Washington University;Department of Anatomy and Neurobiology)

2003-06-06

108

PPAR{alpha} is a potential therapeutic target of drugs to treat circadian rhythm sleep disorders  

SciTech Connect

Recent progress at the molecular level has revealed that nuclear receptors play an important role in the generation of mammalian circadian rhythms. To examine whether peroxisome proliferator-activated receptor alpha (PPAR{alpha}) is involved in the regulation of circadian behavioral rhythms in mammals, we evaluated the locomotor activity of mice administered with the hypolipidemic PPAR{alpha} ligand, bezafibrate. Circadian locomotor activity was phase-advanced about 3 h in mice given bezafibrate under light-dark (LD) conditions. Transfer from LD to constant darkness did not change the onset of activity in these mice, suggesting that bezafibrate advanced the phase of the endogenous clock. Surprisingly, bezafibrate also advanced the phase in mice with lesions of the suprachiasmatic nucleus (SCN; the central clock in mammals). The circadian expression of clock genes such as period2, BMAL1, and Rev-erb{alpha} was also phase-advanced in various tissues (cortex, liver, and fat) without affecting the SCN. Bezafibrate also phase-advanced the activity phase that is delayed in model mice with delayed sleep phase syndrome (DSPS) due to a Clock gene mutation. Our results indicated that PPAR{alpha} is involved in circadian clock control independently of the SCN and that PPAR{alpha} could be a potent target of drugs to treat circadian rhythm sleep disorders including DSPS.

Shirai, Hidenori [Clock Cell Biology Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8566 (Japan); Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8502 (Japan); Oishi, Katsutaka [Clock Cell Biology Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8566 (Japan); Kudo, Takashi [Division of Physiology and Pharmacology, School of Science and Engineering, Waseda University, Nishitokyo, Tokyo 202-0021 (Japan); Shibata, Shigenobu [Division of Physiology and Pharmacology, School of Science and Engineering, Waseda University, Nishitokyo, Tokyo 202-0021 (Japan); Ishida, Norio [Clock Cell Biology Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8566 (Japan) and Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8502 (Japan)]. E-mail: n.ishida@aist.go.jp

2007-06-08

109

[Is there a circadian rhythm of interleukin 15 in humans?].  

PubMed

Nine healthy young men were studied under strict conditions for 48 h. The subjects were selected after a clinical examination and exploration of their rest-activity rhythm by actometry. The circadian rhythms of cortisol (peak at 8 AM) and melatonin (peak at 4 AM) were confirmed. The interleukin 15 (IL-15) was detected in the plasma samples with an Elisa kit (R&D System), but no reproducible variation could be observed during day 1 and day 2. In conclusion, in the conditions of our study, no rhythm was observed for IL-15. Our population will be completed with the inclusion of 6 additional subjects. These results will be specified. PMID:12852986

Chevalier, V; Gachon, F; Kwiatkowski, F; Papon, J; Curé, H; Doly, M; Madelmont, J-C; Chollet, Ph

2003-06-01

110

Disrupted Circadian Rhythms in a Mouse Model of Schizophrenia  

PubMed Central

Summary Sleep and circadian rhythm disruption has been widely observed in neuropsychiatric disorders including schizophrenia [1] and often precedes related symptoms [2]. However, mechanistic basis for this association remains unknown. Therefore, we investigated the circadian phenotype of blind-drunk (Bdr), a mouse model of synaptosomal-associated protein (Snap)-25 exocytotic disruption that displays schizophrenic endophenotypes modulated by prenatal factors and reversible by antipsychotic treatment [3, 4]. Notably, SNAP-25 has been implicated in schizophrenia from genetic [5–8], pathological [9–13], and functional studies [14–16]. We show here that the rest and activity rhythms of Bdr mice are phase advanced and fragmented under a light/dark cycle, reminiscent of the disturbed sleep patterns observed in schizophrenia. Retinal inputs appear normal in mutants, and clock gene rhythms within the suprachiasmatic nucleus (SCN) are normally phased both in vitro and in vivo. However, the 24 hr rhythms of arginine vasopressin within the SCN and plasma corticosterone are both markedly phase advanced in Bdr mice. We suggest that the Bdr circadian phenotype arises from a disruption of synaptic connectivity within the SCN that alters critical output signals. Collectively, our data provide a link between disruption of circadian activity cycles and synaptic dysfunction in a model of neuropsychiatric disease.

Oliver, Peter L.; Sobczyk, Melanie V.; Maywood, Elizabeth S.; Edwards, Benjamin; Lee, Sheena; Livieratos, Achilleas; Oster, Henrik; Butler, Rachel; Godinho, Sofia I.H.; Wulff, Katharina; Peirson, Stuart N.; Fisher, Simon P.; Chesham, Johanna E.; Smith, Janice W.; Hastings, Michael H.; Davies, Kay E.; Foster, Russell G.

2012-01-01

111

Circadian rhythm in cardiac arrest: the Singapore experience  

Microsoft Academic Search

Introduction : There appears to be a circadian rhythm in the timing of cardiovascular and neurovascular events. The majority of studies have been conducted in western populations. This is the first study to look at the peaks and distribution of out-of-hospital cardiac arrest (OHCA) patients in Singapore.

Alfred T

112

Circadian Rhythms and Sleep Patterns in Urban Greek Couples  

Microsoft Academic Search

A convenience sample of 14 adults (seven couples) who intentionally nap regularly was recruited to describe circadian rhythms and sleep patterns in a culture in which afternoon naps are routine. Participants wore a wrist actigraph for 48 hr during May to obtain two peaks and troughs of activity data. Peak activity, estimated by cosinor analysis (acrophase), occurred at 1542 hours

Kathryn A. Lee; Yewoubdar Beyene; Thomas J. Paparrigopoulos; Dimitris G. Dikeos; Constantin R. Soldatos

2007-01-01

113

Circadian rhythms in the activity of a plant protein kinase.  

PubMed

Bryophyllum fedtschenkoi is a Crassulacean acid metabolism plant whose phosphoenolpyruvate carboxylase is regulated by reversible phosphorylation in response to a circadian rhythm. A partially purified protein kinase phosphorylated phosphoenolpyruvate carboxylase in vitro with a stoichiometry approaching one per subunit and caused a concomitant 5- to 10-fold decrease in the sensitivity of the carboxylase to inhibition by malate. The sites phosphorylated in vitro were identical to those phosphorylated in intact tissue. The activity of the protein kinase was controlled in a circadian fashion. During normal diurnal cycles, kinase activity appeared between 4 and 5 h after the onset of darkness and disappeared 2----3 h before the end of darkness. Kinase activity displayed circadian oscillations in constant environmental conditions. The activity of protein phosphatase 2A, which dephosphorylates phosphoenolpyruvate carboxylase, did not oscillate. Treatment of detached leaves with the protein synthesis inhibitors puromycin and cycloheximide blocked the nocturnal appearance of the protein kinase activity, maintained phosphoenolypyruvate carboxylase in the dephosphorylated state and blocked the circadian rhythms of CO2 output that is observed in constant darkness and CO2-free air. The simplest explanation of the data is that there is a circadian rhythm in the synthesis of phosphoenolpyruvate carboxylase kinase. PMID:2065654

Carter, P J; Nimmo, H G; Fewson, C A; Wilkins, M B

1991-08-01

114

Circadian rhythms in the activity of a plant protein kinase.  

PubMed Central

Bryophyllum fedtschenkoi is a Crassulacean acid metabolism plant whose phosphoenolpyruvate carboxylase is regulated by reversible phosphorylation in response to a circadian rhythm. A partially purified protein kinase phosphorylated phosphoenolpyruvate carboxylase in vitro with a stoichiometry approaching one per subunit and caused a concomitant 5- to 10-fold decrease in the sensitivity of the carboxylase to inhibition by malate. The sites phosphorylated in vitro were identical to those phosphorylated in intact tissue. The activity of the protein kinase was controlled in a circadian fashion. During normal diurnal cycles, kinase activity appeared between 4 and 5 h after the onset of darkness and disappeared 2----3 h before the end of darkness. Kinase activity displayed circadian oscillations in constant environmental conditions. The activity of protein phosphatase 2A, which dephosphorylates phosphoenolpyruvate carboxylase, did not oscillate. Treatment of detached leaves with the protein synthesis inhibitors puromycin and cycloheximide blocked the nocturnal appearance of the protein kinase activity, maintained phosphoenolypyruvate carboxylase in the dephosphorylated state and blocked the circadian rhythms of CO2 output that is observed in constant darkness and CO2-free air. The simplest explanation of the data is that there is a circadian rhythm in the synthesis of phosphoenolpyruvate carboxylase kinase. Images

Carter, P J; Nimmo, H G; Fewson, C A; Wilkins, M B

1991-01-01

115

Circadian rhythms and fractal fluctuations in forearm motion  

NASA Astrophysics Data System (ADS)

Recent studies have shown that the circadian pacemaker --- an internal body clock located in the brain which is normally synchronized with the sleep/wake behavioral cycles --- influences key physiologic functions such as the body temperature, hormone secretion and heart rate. Surprisingly, no previous studies have investigated whether the circadian pacemaker impacts human motor activity --- a fundamental physiologic function. We investigate high-frequency actigraph recordings of forearm motion from a group of young and healthy subjects during a forced desynchrony protocol which allows to decouple the sleep/wake cycles from the endogenous circadian cycle while controlling scheduled behaviors. We investigate both static properties (mean value, standard deviation), dynamical characteristics (long-range correlations), and nonlinear features (magnitude and Fourier-phase correlations) in the fluctuations of forearm acceleration across different circadian phases. We demonstrate that while the static properties exhibit significant circadian rhythms with a broad peak in the afternoon, the dynamical and nonlinear characteristics remain invariant with circadian phase. This finding suggests an intrinsic multi-scale dynamic regulation of forearm motion the mechanism of which is not influenced by the circadian pacemaker, thus suggesting that increased cardiac risk in the early morning hours is not related to circadian-mediated influences on motor activity.

Hu, Kun; Hilton, Michael F.

2005-03-01

116

Circadian Clock Proteins in Prokaryotes: Hidden Rhythms?  

PubMed Central

Circadian clock genes are vital features of eukaryotes that have evolved such that organisms can adapt to our planet's rotation in order to anticipate the coming day or night as well as unfavorable seasons. This circadian clock uses oscillation as a timekeeping element. However, circadian clock mechanisms exist also in prokaryotes. The circadian clock of Cyanobacteria is well studied. It is regulated by a cluster of three genes: kaiA, kaiB, and kaiC. In this review, we will discuss the circadian system in cyanobacteria, and provide an overview and updated phylogenetic analysis of prokaryotic organisms that contain the main circadian genes. It is evident that the evolution of the kai genes has been influenced by lateral transfers but further and deeper studies are needed to get an in depth understanding of the exact evolutionary history of these genes. Interestingly, Legionella pneumophila an environmental bacterium and opportunistic human pathogen that parasitizes protozoa in fresh water environments also contains kaiB and kaiC, but their functions are not known. All of the residues described for the biochemical functions of the main pacemaker KaiC in Synechococcus elongatus are also conserved in the L. pneumophila KaiC protein.

Loza-Correa, Maria; Gomez-Valero, Laura; Buchrieser, Carmen

2010-01-01

117

Neuroimaging, cognition, light and circadian rhythms  

PubMed Central

In humans, sleep and wakefulness and the associated cognitive processes are regulated through interactions between sleep homeostasis and the circadian system. Chronic disruption of sleep and circadian rhythmicity is common in our society and there is a need for a better understanding of the brain mechanisms regulating sleep, wakefulness and associated cognitive processes. This review summarizes recent investigations which provide first neural correlates of the combined influence of sleep homeostasis and circadian rhythmicity on cognitive brain activity. Markers of interindividual variations in sleep-wake regulation, such as chronotype and polymorphisms in sleep and clock genes, are associated with changes in cognitive brain responses in subcortical and cortical areas in response to manipulations of the sleep-wake cycle. This review also includes recent data showing that cognitive brain activity is regulated by light, which is a powerful modulator of cognition and alertness and also directly impacts sleep and circadian rhythmicity. The effect of light varied with age, psychiatric status, PERIOD3 genotype and changes in sleep homeostasis and circadian phase. These data provide new insights into the contribution of demographic characteristics, the sleep-wake cycle, circadian rhythmicity and light to brain functioning.

Gaggioni, Giulia; Maquet, Pierre; Schmidt, Christina; Dijk, Derk-Jan; Vandewalle, Gilles

2014-01-01

118

Microarray Analysis of Natural Socially-Regulated Plasticity in Circadian Rhythms of Honey Bees  

PubMed Central

Honey bee workers care for ("nurse") the brood around the clock without circadian rhythmicity, but then they forage outside with strong circadian rhythms and a consolidated nightly rest. This chronobiological plasticity is associated with variation in the expression of the canonical “clock genes” that regulate the circadian clock: nurse bees show no brain rhythms of expression, while foragers do. These results suggest that the circadian system is organized differently in nurses and foragers. Nurses switch to activity with circadian rhythms shortly after removed from the hive suggesting that at least some clock cells in their brain continue to measure time while in the hive. We performed a microarray genome-wide survey to determine general patterns of brain gene expression in nurses and foragers sampled around the clock. We found 160 and 541 transcripts that exhibited significant sinusoidal oscillations in nurses and foragers, respectively, with peaks of expression distributed throughout the day in both task groups. Consistent with earlier studies, transcripts of genes involved in circadian rhythms, including Clockwork Orange that has not been studied before in bees, oscillated in foragers but not in nurses. The oscillating transcripts also were enriched for genes involved in the visual system, “development” and “response to stimuli” (foragers), “muscle contraction” and “microfilament motor gene expression” (nurses), and “generation of precursor metabolites” and “energy” (both). Transcripts of genes encoding P450 enzymes oscillated in both nurses and foragers but with a different phase. This study identified new putative clock-controlled genes in the honey bee and suggests that some brain functions show circadian rhythmicity even in nurse bees that are active around the clock.

Rodriguez-Zas, Sandra L.; Southey, Bruce R.; Shemesh, Yair; Rubin, Elad B.; Cohen, Mira; Robinson, Gene E.; Bloch, Guy

2012-01-01

119

Circadian rhythms in prokaryotes: luciferase as a reporter of circadian gene expression in cyanobacteria.  

PubMed Central

We have used a luciferase reporter gene and continuous automated monitoring of bioluminescence to demonstrate unequivocally that cyanobacteria exhibit circadian behaviors that are fundamentally the same as circadian rhythms of eukaryotes. We also show that these rhythms can be studied by molecular methods in Synechococcus sp. PCC7942, a strain for which genetic transformation is well established. A promoterless segment of the Vibrio harveyi luciferase structural genes (luxAB) was introduced downstream of the promoter for the Synechococcus psbAI gene, which encodes a photosystem II protein. This reporter construction was recombined into the Synechococcus chromosome, and bioluminescence was monitored under conditions of constant illumination following entrainment to light and dark cycles. The reporter strain, AMC149, expressed a rhythm of bioluminescence which satisfies the criteria of circadian rhythms: persistence in constant conditions, phase resetting by light/dark signals, and temperature compensation of the period. Rhythmic changes in levels of the native psbAI message following light/dark entrainment supported the reporter data. The behavior of this prokaryote disproves the dogma that circadian mechanisms must be based on eukaryotic cellular organization. Moreover, the cyanobacterial strain described here provides an efficient experimental system for molecular analysis of the circadian clock. Images Fig. 2

Kondo, T; Strayer, C A; Kulkarni, R D; Taylor, W; Ishiura, M; Golden, S S; Johnson, C H

1993-01-01

120

Quantification of Circadian Rhythms in Single Cells  

PubMed Central

Bioluminescence techniques allow accurate monitoring of the circadian clock in single cells. We have analyzed bioluminescence data of Per gene expression in mouse SCN neurons and fibroblasts. From these data, we extracted parameters such as damping rate and noise intensity using two simple mathematical models, one describing a damped oscillator driven by noise, and one describing a self-sustained noisy oscillator. Both models describe the data well and enabled us to quantitatively characterize both wild-type cells and several mutants. It has been suggested that the circadian clock is self-sustained at the single cell level, but we conclude that present data are not sufficient to determine whether the circadian clock of single SCN neurons and fibroblasts is a damped or a self-sustained oscillator. We show how to settle this question, however, by testing the models' predictions of different phases and amplitudes in response to a periodic entrainment signal (zeitgeber).

Westermark, Pal O.; Welsh, David K.; Okamura, Hitoshi; Herzel, Hanspeter

2009-01-01

121

Post-Translational Modifications in Circadian Rhythms  

PubMed Central

The pace has quickened in circadian biology research. In particular, an abundance of results focused on post-translational modifications (PTMs) is sharpening our view of circadian molecular clockworks. PTMs affect nearly all aspects of clock biology; in some cases they are essential for clock function and in others, they provide layers of regulatory fine-tuning. Our goal is to review recent advances in clock PTMs, help make sense of emerging themes, and spotlight intriguing and perhaps controversial new findings. We focus on PTMs affecting the core functions of eukaryotic clocks, in particular the functionally related oscillators in Neurospora crassa, Drosophila melanogaster, and mammalian cells.

Mehra, Arun; Baker, Christopher L.; Loros, Jennifer J.; Dunlap, Jay C.

2009-01-01

122

Sleep and Circadian Rhythms in Four Orbiting Astronauts  

NASA Technical Reports Server (NTRS)

INTRODUCTION The study of human sleep and circadian rhythms in space has both operational and scientific significance. Operationally, U.S. Spaceflight is moving away from brief missions with durations of less than one week. Most space shuttle missions now last two weeks or more, and future plans involving space stations, lunar bases and interplanetary missions all presume that people will be living away from the gravity and time cues of earth for months at a time. Thus, missions are moving away from situations where astronauts can "tough it out" for comparatively brief durations, to situations where sleep and circadian disruptions are likely to become chronic, and thus resistant to short term pharmacological or behavioral manipulations. As well as the operational significance, there is a strong theoretical imperative for studying the sleep and circadian rhythms of people who are removed from the gravity and time cues of earth. Like other animals, in humans, the Circadian Timekeeping System (CTS) is entrained to the correct period (24h) and temporal orientation by various time cues ("zeitgebers"), the most powerful of which is the alternation of daylight and darkness. In leaving Earth, astronauts are removing themselves from the prime zeitgeber of their circadian system -- the 24h alternation of daylight and darkness.

Monk, Timothy H.; Buysse, Daniel J.; Billy, Bart D.; Kennedy, Kathy S.; Willrich, Linda M.

1999-01-01

123

Sleep and circadian rhythm during a short space mission.  

PubMed

An experiment was conducted to assess sleep and circadian regulation in an orbiting spacecraft. In orbit the weakened influence of 24-h zeitgebers could result in delayed circadian phases with the possibility of a transition to free-running circadian rhythms. This and the specific stressors of a space mission may lead to changes in ultradian sleep regulation and in reduced sleep quantity and quality. During the mission sleep was recorded polygraphically on tape, as was body temperature. Daytime alertness was rated subjectively by a mood questionnaire. For comparison the same parameters were measured during a baseline period preceding the space mission. The circadian rhythms of body temperature and alertness were found to be delayed in space compared to baseline. This may mark a phase shift or the transition to a circadian state of free-run. Sleep was shorter and more disturbed. The structure of sleep was significantly altered. In space REM latency was shorter, there was less REM sleep in the second non-REM/REM cycle, and slow-wave sleep was redistributed from the first to the second cycle. The self-assessed mood resembled sleep disturbances and adaptation to the space environment. Reduced sleep quality and quantity are likely to result in fatigue and lower daytime performance. Countermeasures should be adopted to improve sleep of astronauts. PMID:8241722

Gundel, A; Nalishiti, V; Reucher, E; Vejvoda, M; Zulley, J

1993-09-01

124

Age, circadian rhythms, and sleep loss in flight crews  

NASA Technical Reports Server (NTRS)

Age-related changes in trip-induced sleep loss, personality, and the preduty temperature rhythm were analyzed in crews from various flight operations. Eveningness decreased with age. The minimum of the baseline temperature rhythm occurred earlier with age. The amplitude of the baseline temperature rhythm declined with age. Average daily percentage sleep loss during trips increased with age. Among crewmembers flying longhaul flight operations, subjects aged 50-60 averaged 3.5 times more sleep loss per day than subjects aged 20-30. These studies support previous findings that evening types and subjects with later peaking temperature rhythms adapt better to shift work and time zone changes. Age and circadian type may be important considerations for duty schedules and fatigue countermeasures.

Gander, Philippa H.; Nguyen, DE; Rosekind, Mark R.; Connell, Linda J.

1993-01-01

125

CIRCADIAN RHYTHMS Chronobiology--Reducing Time  

NSDL National Science Digital Library

The authors provide perspective on two papers from the McKnight group, on pages 506 (2) and 510 (3) of this issue, which report on a fascinating discovery that may provide an unexpected molecular link between circadian oscillations and energy homeostasis.

Ueli Schibler (University of Geneva;Department of Molecular Biology, Sciences II); Juergen Ripperger (University of Geneva;Department of Molecular Biology, Sciences II); Steven Brown (University of Zurich;Department of Molecular Biology, Sciences II,)

2001-07-05

126

Chronoendocrinological studies in athletes. Circadian rhythms of HGH and IRI.  

PubMed

The serum concentrations of HGH and IRI studied over a 24-hour span in 83 healthy athletes under normal rest conditions in a normal living environment show statistically significant rhythms, validated and quantified by cosinor analysis; for each hormone three different types of the circadian rhythm (with a peak of acrophase between: 6.30 a.m. and 1.30 p.m., 1.30 p.m. and 10.30 p.m., 10.30 p.m. and 6.30 a.m.) were observed. The IRI response to a meal load underwent cyclic variations during the day. PMID:506752

Dobrza?ski, T; Zurowski, S; Graban, W

1979-01-01

127

Circadian rhythms and behavior of permanent nightworkers  

Microsoft Academic Search

Summary This paper describes rest\\/activity rhythms of permanent shift workers: rotary printers. They reported during one week the hours of their sleep onset and of their meals, and their subjective appreciation of tiredness and mood. The average sleep duration (7.84 h) can be compared with that of day workers and is fairly longer than the duration of day sleep of

M. Lortie; J. Foret; C. Teiger; A. Laville

1979-01-01

128

Links between Circadian Rhythms and Psychiatric Disease  

PubMed Central

Determining the cause of psychiatric disorders is a goal of modern neuroscience, and will hopefully lead to the discovery of treatments to either prevent or alleviate the suffering caused by these diseases. One roadblock to attaining this goal is the realization that neuropsychiatric diseases are rarely due to a single gene polymorphism, environmental exposure, or developmental insult. Rather, it is a complex interaction between these various influences that likely leads to the development of clinically relevant syndromes. Our lab is exploring the links between environmental exposures and neurobehavioral function by investigating how disruption of the circadian (daily) clock alters the structure and function of neural circuits, with the hypothesis that disrupting this crucial homeostatic system can directly contribute to altered vulnerability of the organism to other factors that interact to produce psychiatric illness. This review explores some historical and more recent findings that link disrupted circadian clocks to neuropsychiatric disorders, particularly depression, mania, and schizophrenia. We take a comparative approach by exploring the effects observed in human populations, as well as some experimental models used in the laboratory to unravel mechanistic and causal relationships between disruption of the circadian clock and behavioral abnormalities. This is a rich area of research that we predict will contribute greatly to our understanding of how genes, environment, and development interact to modulate an individual’s vulnerability to psychiatric disorders.

Karatsoreos, Ilia N.

2014-01-01

129

Circadian rhythms in the hypothalamo–pituitary–adrenal (HPA) axis  

Microsoft Academic Search

The pronounced daily variation in the release of adrenal hormones has been at the heart of the deciphering and understanding of the circadian timing system. Indeed, the first demonstration of an endocrine day\\/night rhythm was provided by Pincus (1943), by showing a daily pattern of 17-keto-steroid excretion in the urine of 7 healthy males. Twenty years later the adrenal gland

A. Kalsbeek; R. van der Spek; J. Lei; E. Endert; R. M. Buijs; E. Fliers

130

Normative values for circadian and ultradian cardiovascular rhythms in childhood.  

PubMed

To assess the prevalence and characteristics of physiological circadian (24-hour) and ultradian (12-, 8-, and 6-hour) rhythms of mean arterial blood pressure (BP) and heart rate (HR), we analyzed 24-hour ambulatory BP profiles from 938 healthy school children aged 5 to 18 years. Cosine harmonics were fitted by Fourier analysis, and an amplitude and acrophase (time of peak) were calculated for each rhythm. Ninety percent of children displayed circadian rhythmicity of BP, independent of age, whereas circadian HR rhythmicity decreased with puberty from 96% to 87% (P<0.0001). Puberty had marked effects on the prevalence of ultradian rhythmicity: 12- and 6-hour rhythms increased for BP (27% to 47%, P<0.0001; 18% to 25%, P=0.01) and HR (36% to 47%, 17% to 31%, both P=0.001), whereas 8-hour BP rhythms decreased (34% to 23%, P=0.002). Median amplitudes were 10.1, 5.9, 5.6, and 5.2 mm Hg for the 24-, 12-, 8-, and 6-hour BP rhythms, respectively, and 13.4, 7.7, 6.8, and 6.4 bpm for HR. The acrophase occurred at approximately 14:00 hours, 8:00 hours, 5:30 hours, and 2:00 hours (military time) for the four BP rhythms, and at 13:30 hours, 08:30 hours, 01:50 hours, and 02:00 hours for HR. For the combined curve, the peak-trough difference was 25.9 mm Hg and 35 bpm for BP and HR, respectively, with the peaks occurring at 13:50 hours and 13:10 hours. There was marked association between BP and HR rhythms, both for prevalence (P<0.0001 for coupling of BP and HR rhythms of the same period length) and timing, with a median time lag of BP after HR acrophase of only 21, 16, 13, and 5 minutes for the four rhythms, respectively. PMID:14744931

Hadtstein, Charlotte; Wühl, Elke; Soergel, Marianne; Witte, Klaus; Schaefer, Franz

2004-03-01

131

Familial Circadian Rhythm Disorder in the Diurnal Primate, Macaca mulatta  

PubMed Central

In view of the inverse temporal relationship of central clock activity to physiological or behavioral outputs in diurnal and nocturnal species, understanding the mechanisms and physiological consequences of circadian disorders in humans would benefit from studies in a diurnal animal model, phylogenetically close to humans. Here we report the discovery of the first intrinsic circadian disorder in a family of diurnal non-human primates, the rhesus monkey. The disorder is characterized by a combination of delayed sleep phase, relative to light-dark cycle, mutual desynchrony of intrinsic rhythms of activity, food intake and cognitive performance, enhanced nighttime feeding or, in the extreme case, intrinsic asynchrony. The phenotype is associated with normal length of intrinsic circadian period and requires an intact central clock, as demonstrated by an SCN lesion. Entrainment to different photoperiods or melatonin administration does not eliminate internal desynchrony, though melatonin can temporarily reinstate intrinsic activity rhythms in the animal with intrinsic asynchrony. Entrainment to restricted feeding is highly effective in animals with intrinsic or SCN lesion-induced asynchrony. The large isolated family of rhesus macaques harboring the disorder provides a powerful new tool for translational research of regulatory circuits underlying circadian disorders and their effective treatment.

Zhdanova, Irina V.; Masuda, Ken; Bozhokin, Sergey V.; Rosene, Douglas L.; Gonzalez-Martinez, Janis; Schettler, Steven; Samorodnitsky, Eric

2012-01-01

132

Predicted microRNAs for mammalian circadian rhythms.  

PubMed

There is little evidence for the involvement of microRNAs (miRs) in the regulation of circadian rhythms, despite the potential relevance of these elements in the posttranscriptional regulation of the clock machinery. The present work aimed to identify miRs targeting circadian genes through a predictive analysis of conserved miRs in mammals. Besides 23 miRs previously associated with circadian rhythms, we found a number of interesting candidate genes, equally predicted by the 3 software programs used, including miR-9, miR-24, miR25, miR-26, miR-27, miR-29, miR-93, miR-211, miR-302, and miR-346. Moreover, several miRs are predicted to be regulated by circadian transcription factors, such as CLOCK/BMAL, DEC2, and REV-ERBalpha. Using real-time PCR we demonstrated that the selected candidate miR-27b showed a daily variation in human leukocytes. This study presents predicted feedback loops for mammalian molecular clock and the first description of an miR with in vivo daily variation in humans. PMID:23606610

Figueredo, Diego de Siqueira; Barbosa, Mayara Rodrigues; Gitaí, Daniel Leite Góes; de Andrade, Tiago Gomes

2013-04-01

133

Familial circadian rhythm disorder in the diurnal primate, Macaca mulatta.  

PubMed

In view of the inverse temporal relationship of central clock activity to physiological or behavioral outputs in diurnal and nocturnal species, understanding the mechanisms and physiological consequences of circadian disorders in humans would benefit from studies in a diurnal animal model, phylogenetically close to humans. Here we report the discovery of the first intrinsic circadian disorder in a family of diurnal non-human primates, the rhesus monkey. The disorder is characterized by a combination of delayed sleep phase, relative to light-dark cycle, mutual desynchrony of intrinsic rhythms of activity, food intake and cognitive performance, enhanced nighttime feeding or, in the extreme case, intrinsic asynchrony. The phenotype is associated with normal length of intrinsic circadian period and requires an intact central clock, as demonstrated by an SCN lesion. Entrainment to different photoperiods or melatonin administration does not eliminate internal desynchrony, though melatonin can temporarily reinstate intrinsic activity rhythms in the animal with intrinsic asynchrony. Entrainment to restricted feeding is highly effective in animals with intrinsic or SCN lesion-induced asynchrony. The large isolated family of rhesus macaques harboring the disorder provides a powerful new tool for translational research of regulatory circuits underlying circadian disorders and their effective treatment. PMID:22413014

Zhdanova, Irina V; Masuda, Ken; Bozhokin, Sergey V; Rosene, Douglas L; González-Martínez, Janis; Schettler, Steven; Samorodnitsky, Eric

2012-01-01

134

Circadian rhythm dissociation in an environment with conflicting temporal information  

NASA Technical Reports Server (NTRS)

The relative contributions of light-dark (LD) cycles and eating-fasting (EF) cycles in providing temporal information to the circadian time-keeping system were examined in chair-acclimatized squirrel monkeys (Saimiri sciureus). The circadian rhythms of drinking, colonic temperature, urine volume, and urinary potassium excretion were measured with the LD and EF cycles providing either conflicting phases or periods. In conflicting phase experiments, animals were exposed to 24-hr LD cycles consisting of 12 hr of 600 lx followed by 12 hr of less than 1 lx and concurrent 24-hr EF cycles in which the animals ate for 3 hr and then fasted for 21 hr. One group had food available at the beginning and a second group at the end of the light period. In conflicting period experiments, monkeys were exposed to 23-hr LD cycles and 24-hr EF cycles. Analysis of the rhythms showed that both phase and period information were conveyed to the drinking and urinary rhythms by the EF cycle, and to the temperature rhythm by the LD cycle.

Sulzman, F. M.; Fuller, C. A.; Hiles, L. G.; Moore-Ede, M. C.

1978-01-01

135

Circadian activity rhythms and mortality: the Study of Osteoporotic Fractures  

PubMed Central

OBJECTIVES To determine whether circadian activity rhythms are associated with mortality in community-dwelling older women. DESIGN Prospective study of mortality. SETTING A cohort study of health and aging. PARTICIPANTS 3,027 community-dwelling women from the Study of Osteoporotic Fractures cohort (mean age 84 years). MEASUREMENTS Activity data were collected with wrist actigraphy for a minimum of three 24-hour periods and circadian activity rhythms were computed. Parameters of interest included height of activity peak (amplitude), mean activity level (mesor), strength of activity rhythm (robustness), and time of peak activity (acrophase). Vital status, with cause of death adjudicated through death certificates, was prospectively ascertained. RESULTS Over an average of 4.1 years of follow-up there were 444 (15%) deaths. There was an inverse association between peak activity height and all-cause mortality rates with higher mortality rates observed in the lowest activity quartile (Hazard ratio [HR]=2.18, 95% CI, 1.63–2.92) compared with the highest quartile after adjusting for age, clinic site, race, BMI, cognitive function, exercise, IADL impairments, depression, medications, alcohol, smoking, self-reported health status, married status, and co-morbidities. Increased risk of all-cause mortality was observed between lower mean activity level (HR=1.71, 95% CI, 1.29–2.27) and rhythm robustness (HR=1.97, 95% CI, 1.50–2.60). Increased mortality from cancer (HR=2.09, 95% CI, 1.04–4.22) and stroke (HR=2.64, 95% CI, 1.11–6.30) was observed for a delayed timing of peak activity (after 4:33PM; >1.5 SD from mean) when compared to the mean peak range (2:50PM–4:33PM). CONCLUSION Older women with weak circadian activity rhythms have higher mortality risk. If confirmed in other cohorts, studies will be needed to test whether interventions (e.g. physical activity, bright light exposure) that regulate circadian activity rhythms will improve health outcomes in the elderly.

Tranah, Gregory J.; Blackwell, Terri; Ancoli-Israel, Sonia; Paudel, Misti L.; Ensrud, Kristine E.; Cauley, Jane A.; Redline, Susan; Hillier, Teresa A.; Cummings, Steven R; Stone, Katie L.

2010-01-01

136

Causal involvement of mammalian-type cryptochrome in the circadian cuticle deposition rhythm in the bean bug Riptortus pedestris.  

PubMed

Mammalian-type CRYPTOCHROME (CRY-m) is considered to be a core repressive component of the circadian clock in various insect species. However, this role is based only on the molecular function of CRY-m in cultured cells and it therefore remains unknown whether CRY-m is indispensable for governing physiological rhythms at the organismal level. In the present study, we show that RNA interference (RNAi) targeting of cry-m in the bean bug Riptortus pedestris disrupts the circadian clock governing the cuticle deposition rhythm and results in the generation of a single cuticle layer. Furthermore, period expression was induced in cry-m RNAi insects. These results verified that CRY-m functions as a negative regulator in the circadian clock that generates physiological rhythm at the organismal level. PMID:21435062

Ikeno, T; Katagiri, C; Numata, H; Goto, S G

2011-06-01

137

An allele of the crm gene blocks cyanobacterial circadian rhythms  

PubMed Central

The SasA-RpaA two-component system constitutes a key output pathway of the cyanobacterial Kai circadian oscillator. To date, rhythm of phycobilisome associated (rpaA) is the only gene other than kaiA, kaiB, and kaiC, which encode the oscillator itself, whose mutation causes completely arrhythmic gene expression. Here we report a unique transposon insertion allele in a small ORF located immediately upstream of rpaA in Synechococcus elongatus PCC 7942 termed crm (for circadian rhythmicity modulator), which results in arrhythmic promoter activity but does not affect steady-state levels of RpaA. The crm ORF complements the defect when expressed in trans, but only if it can be translated, suggesting that crm encodes a small protein. The crm1 insertion allele phenotypes are distinct from those of an rpaA null; crm1 mutants are able to grow in a light:dark cycle and have no detectable oscillations of KaiC phosphorylation, whereas low-amplitude KaiC phosphorylation rhythms persist in the absence of RpaA. Levels of phosphorylated RpaA in vivo measured over time are significantly altered compared with WT in the crm1 mutant as well as in the absence of KaiC. Taken together, these results are consistent with the hypothesis that the Crm polypeptide modulates a circadian-specific activity of RpaA.

Boyd, Joseph S.; Bordowitz, Juliana R.; Bree, Anna C.; Golden, Susan S.

2013-01-01

138

Circadian rhythm abnormalities of melatonin in Smith-Magenis syndrome  

PubMed Central

BACKGROUND—Smith-Magenis syndrome (SMS) is a multiple congenital anomalies/mental retardation syndrome associated with a hemizygous deletion of chromosome 17, band p11.2. Characteristic features include neurobehavioural abnormalities such as aggressive and self-injurious behaviour and significant sleep disturbances. The majority of patients have a common deletion characterised at the molecular level. Physical mapping studies indicate that all patients with the common deletion are haploinsufficient for subunit 3 of the COP9 signalosome (COPS3), which is conserved from plants to humans, and in the plant Arabidopis thaliana regulates gene transcription in response to light. Haploinsufficiency of this gene is hypothesised to be potentially involved in the sleep disturbances seen in these patients. Melatonin is a hormone secreted by the pineal gland. SMS patients are reported to have fewer sleep disturbances when given a night time dose of this sleep inducing hormone.?METHODS—Urinary excretion of 6-sulphatoxymelatonin (aMT6s), the major hepatic metabolite of melatonin, in 19 SMS patients were measured in conjunction with 24 hour sleep studies in 28 SMS patients. Five of the 28 patients did not have the common SMS deletion. To investigate a potential correlation of COPS3 haploinsufficiency and disturbed melatonin excretion, we performed fluorescence in situ hybridisation (FISH) using two BACs containing coding exons of COPS3.?RESULTS—All SMS patients show significant sleep disturbances when assessed by objective criteria. Abnormalities in the circadian rhythm of aMT6s were observed in all but one SMS patient. Interestingly this patient did not have the common deletion. All patients studied, including the one patient with a normal melatonin rhythm, were haploinsufficient for COPS3.?CONCLUSIONS—Our data indicate a disturbed circadian rhythm in melatonin and document the disturbed sleep pattern in Smith-Magenis syndrome. Our findings suggest that the abnormalities in the circadian rhythm of melatonin and altered sleep patterns could be secondary to aberrations in the production, secretion, distribution, or metabolism of melatonin; however, a direct role for COPS3 could not be established.???Keywords: melatonin; circadian rhythms; Smith-Magenis syndrome; COPS3

Potocki, L.; Glaze, D.; Tan, D.; Park, S.; Kashork, C.; Shaffer, L.; Reiter, R.; Lupski, J.

2000-01-01

139

Interconnections of Reactive Oxygen Species Homeostasis and Circadian Rhythm in Neurospora crassa.  

PubMed

Abstract Significance: Both circadian rhythm and the production of reactive oxygen species (ROS) are fundamental features of aerobic eukaryotic cells. The circadian clock enhances the fitness of organisms by enabling them to anticipate cycling changes in the surroundings. ROS generation in the cell is often altered in response to environmental changes, but oscillations in ROS levels may also reflect endogenous metabolic fluctuations governed by the circadian clock. On the other hand, an effective regulation and timing of antioxidant mechanisms may be crucial in the defense of cellular integrity. Thus, an interaction between the circadian timekeeping machinery and ROS homeostasis or signaling in both directions may be of advantage at all phylogenetic levels. Recent Advances: The Frequency-White Collar-1 and White Collar-2 oscillator (FWO) of the filamentous fungus Neurospora crassa is well characterized at the molecular level. Several members of the ROS homeostasis were found to be controlled by the circadian clock, and ROS levels display circadian rhythm in Neurospora. On the other hand, multiple data indicate that ROS affect the molecular oscillator. Critical Issues: Increasing evidence suggests the interplay between ROS homeostasis and oscillators that may be partially or fully independent of the FWO. In addition, ROS may be part of a complex cellular network synchronizing non-transcriptional oscillators with timekeeping machineries based on the classical transcription-translation feedback mechanism. Future Directions: Further investigations are needed to clarify how the different layers of the bidirectional interactions between ROS homeostasis and circadian regulation are interconnected. Antioxid. Redox Signal. 20, 3007-3023. PMID:23964982

Gyöngyösi, Norbert; Káldi, Krisztina

2014-06-20

140

The prediction of the adaptation of circadian rhythms to rapid time zone changes  

Microsoft Academic Search

The aim of the study was to find out which factors could explain individual differences in the resynchronization speed of circadian rhythms of salivary melatonin and subjective alertness after transmeridian flights over 10 time zones. The mean age of the 40 female subjects was 33·0 ±6·9 years. The data were gathered by measurements of the circadian rhythms of melatonin excretion

S. SUVANTO; M. HÄRMA; J. T. LAJTINEN

1993-01-01

141

LHY and CCA1 Are Partially Redundant Genes Required to Maintain Circadian Rhythms in Arabidopsis  

Microsoft Academic Search

Several genes are known to regulate circadian rhythms in Arabidopsis, but the identity of the central oscillator has not been established. LHY and CCA1 are related MYB-like transcription factors proposed to be closely involved. Here we demonstrate that, as shown previously for CCA1, inactivation of LHY shortens the period of circadian rhythms in gene expression and leaf movements. By constructing

Tsuyoshi Mizoguchi; Kay Wheatley; Yoshie Hanzawa; Louisa Wright; Mutsuko Mizoguchi; Hae-Ryong Song; Isabelle A. Carré; George Coupland

2002-01-01

142

Individual neurons dissociated from rat suprachiasmatic nucleus express independently phased circadian firing rhythms  

Microsoft Academic Search

Within the mammalian hypothalamus, the suprachiasmatic nucleus (SCN) contains a circadian clock for timing of diverse neuronal, endocrine, and behavioral rhythms. By culturing cells from neonatal rat SCN on fixed microelectrode arrays, we have been able to record spontaneous action potentials from individual SCN neurons for days or weeks, revealing prominent circadian rhythms in firing rate. Despite abundant functional synapses,

David K. Welsh; Diomedes E. Logothetis; Markus Meister; Steven M. Reppert

1995-01-01

143

Circadian rhythms in a long-term duration space flight  

NASA Astrophysics Data System (ADS)

In order to maintain cosmonaut health and performance, it is important for the work-rest schedule to follow human circadian rhythms (CR). What happens with CR in space flight? Investigations of CR in mammals revealed, that the circadian phase in flight is less stable, probably due to a displacement of the range of entrainment, resulting from internal period change (the latter was confirmed on insects). The circadian period may be a gravity-dependent parameter. If so, the basic biological requirement for the day length might be different in weightlessness. On this basis, a higher risk of desynchronosis is expected in a long-duration space flight. As a countermeasure, a non-24-hr day length could be suggested, being close to the internal circadian period (in humans about 25 hr). Taking into account a possible displacement of period in weightlessness, it seems reasonable to establish a flexible work-rest schedule, capable to follow the body temperature CR by means of biofeedback.

Alpatov, Alexey M.

144

Circadian rhythm disorders among adolescents: assessment and treatment options.  

PubMed

Delayed sleep phase disorder (DSPD) - a circadian rhythm sleep disorder - is most commonly seen in adolescents. The differential diagnosis between DSPD and conventional psychophysiological insomnia is important for correct therapeutic intervention. Adolescent DSPD sleep duration is commonly 9 hours or more. Depression may be comorbid with DSPD. DSPD has a negative impact on adolescent academic performance. DSPD treatments include bright light therapy, chronotherapeutic regimens, and administration of melatonin as a chronobiotic (as distinct from a soporific). Attention to non-photic and extrinsic factors including healthy sleep parameters is also important to enable better sleep and mood outcomes in adolescents. PMID:24138360

Bartlett, Delwyn J; Biggs, Sarah N; Armstrong, Stuart M

2013-10-21

145

Aging human circadian rhythms: conventional wisdom may not always be right  

NASA Technical Reports Server (NTRS)

This review discusses the ways in which the circadian rhythms of older people are different from those of younger adults. After a brief discussion of clinical issues, the review describes the conventional wisdom regarding age-related changes in circadian rhythms. These can be summarized as four assertions regarding what happens to people as they get older: 1) the amplitude of their circadian rhythms reduces, 2) the phase of their circadian rhythms becomes earlier, 3) their natural free-running period (tau) shortens, and 4) their ability to tolerate abrupt phase shifts (e.g., from jet travel or night work) worsens. The review then discusses the empirical evidence for and against these assertions and discusses some alternative explanations. The conclusions are that although older people undoubtedly have earlier circadian phases than younger adults, and have more trouble coping with shift work and jet lag, evidence for the assertions about rhythm amplitude and tau are, at best, mixed.

Monk, Timothy H.

2005-01-01

146

Circadian Rhythms in Gene Expression: Relationship to Physiology, Disease, Drug Disposition and Drug Action  

PubMed Central

Circadian rhythms (24 h cycles) are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body. Components of this core clock mechanism regulate the circadian rhythms in genome-wide mRNA expression, which in turn regulate various biological processes. Disruption of circadian rhythms can be either the cause or the effect of various disorders including metabolic syndrome, inflammatory diseases and cancer. Furthermore, circadian rhythms in gene expression regulate both the action and disposition of various drugs and affect therapeutic efficacy and toxicity based on dosing time. Understanding the regulation of circadian rhythms in gene expression plays an important role in both optimizing the dosing time for existing drugs and in development of new therapeutics targeting the molecular clock.

Sukumaran, Siddharth; Almon, Richard R.; DuBois, Debra C.; Jusko, William J.

2010-01-01

147

Role of Melatonin in the Regulation of Human Circadian Rhythms and Sleep  

Microsoft Academic Search

Abstract The circadian rhythm,of pineal melatonin,is the best marker,of internal time under low ambient,light levels. The endogenous,melatonin,rhythm,exhibits a close association with the endogenous,circadian component,of the sleep propensity rhythm. This has led to the idea that melatonin is an internal sleep ‘facilitator’ in humans, and,therefore useful in the treatment,of insomnia,and the readjustment,of circadian rhythms. There is evidence,that administration of melatonin,is able:

C. Cajochen; K. Kra Uchi; A. Wirz-justice

148

Experiment K-7-35: Circadian Rhythms and Temperature Regulation During Spaceflight. Part 1; Circadian Rhythms and Temperature Regulation  

NASA Technical Reports Server (NTRS)

Mammals have developed the ability to adapt to most variations encountered in their everyday environment. For example, homeotherms have developed the ability to maintain the internal cellular environment at a relatively constant temperature. Also, in order to compensate for temporal variations in the terrestrial environment, the circadian timing system has evolved. However, throughout the evolution of life on earth, living organisms have been exposed to the influence of an unvarying level of earth's gravity. As a result changes in gravity produce adaptive responses which are not completely understood. In particular, spaceflight has pronounced effects on various physiological and behavioral systems. Such systems include body temperature regulation and circadian rhythms. This program has examined the influence of microgravity on temperature regulation and circadian timekeeping systems in Rhesus monkeys. Animals flown on the Soviet Biosatellite, COSMOS 2044, were exposed to 14 days of microgravity while constantly monitoring the circadian patterns temperature regulation, heart rate and activity. This experiment has extended our previous observations from COSMOS 1514, as well as providing insights into the physiological mechanisms that produce these changes.

Fuller, C. A.; Alpatov, A. M.; Hoban-Higgins, T. M.; Klimovitsky, V. Y.

1994-01-01

149

Thoracic surface temperature rhythms as circadian biomarkers for cancer chronotherapy.  

PubMed

The disruption of the temperature circadian rhythm has been associated with cancer progression, while its amplification resulted in cancer inhibition in experimental tumor models. The current study investigated the relevance of skin surface temperature rhythms as biomarkers of the Circadian Timing System (CTS) in order to optimize chronotherapy timing in individual cancer patients. Baseline skin surface temperature at four sites and wrist accelerations were measured every minute for 4 days in 16 patients with metastatic gastro-intestinal cancer before chronotherapy administration. Temperature and rest-activity were recorded, respectively, with wireless skin surface temperature patches (Respironics, Phillips) and an actigraph (Ambulatory Monitoring). Both variables were further monitored in 10 of these patients during and after a 4-day course of a fixed chronotherapy protocol. Collected at baseline, during and after therapy longitudinal data sets were processed using Fast Fourier Transform Cosinor and Linear Discriminant Analyses methods. A circadian rhythm was statistically validated with a period of 24 h (p < 0.05) for 49/61 temperature time series (80.3%), and 15/16 rest-activity patterns (93.7%) at baseline. However, individual circadian amplitudes varied from 0.04 °C to 2.86 °C for skin surface temperature (median, 0.72 °C), and from 16.6 to 146.1 acc/min for rest-activity (median, 88.9 acc/min). Thirty-nine pairs of baseline temperature and rest-activity time series (75%) were correlated (r > |0.7|; p < 0.05). Individual circadian acrophases at baseline were scattered from 15:18 to 6:05 for skin surface temperature, and from 12:19 to 15:18 for rest-activity, with respective median values of 01:10 (25-75% quartiles, 22:35-3:07) and 14:12 (13:14-14:31). The circadian patterns in skin surface temperature and rest-activity persisted or were amplified during and after fixed chronotherapy delivery for 5/10 patients. In contrast, transient or sustained disruption of these biomarkers was found for the five other patients, as indicated by the lack of any statistically significant dominant period in the circadian range. No consistent correlation (r < |0.7|, p ? 0.05) was found between paired rest-activity and temperature time series during fixed chronotherapy delivery. In conclusion, large inter-patient differences in circadian amplitudes and acrophases of skin surface temperature were demonstrated for the first time in cancer patients, despite rather similar rest-activity acrophases. The patient-dependent coupling between both CTS biomarkers, and its possible alteration on a fixed chronotherapy protocol, support the concept of personalized cancer chronotherapy. PMID:24397341

Roche, Véronique Pasquale; Mohamad-Djafari, Ali; Innominato, Pasquale Fabio; Karaboué, Abdoulaye; Gorbach, Alexander; Lévi, Francis Albert

2014-04-01

150

Extracellular low pH affects circadian rhythm expression in human primary fibroblasts  

PubMed Central

Circadian rhythm is a fundamental biological system involved in the regulation of various physiological functions. However, little is known about a nature or function of circadian clock in human primary cells. In the present study, we have applied in vitro real time circadian rhythm monitoring to study human clock properties using primary skin fibroblasts. Among factors that affect human physiology, slightly lower extracellular pH was chosen to test its effects on circadian rhythm expression. We established human primary fibroblast cultures obtained from three healthy subjects, stably delivered a circadian reporter gene Bmal1-luciferase, and recorded circadian rhythms in the culture medium at pH 7.2 and pH 6.7. At pH 7.2, robust and sustained circadian rhythms were observed with average period length 24.47 ± 0.03 h. Such rhythms were also found at pH 6.7; however, period length was significantly shortened to 22.60 ± 0.20, amplitude was increased, and damping rate was decreased. The effect of exposure to low pH on the period length was reversible. The shortened period was unlikely caused by factors affecting cell viability because cell morphology and MTT assay showed no significant difference between the two conditions. In summary, our results showed that the circadian rhythm expression is affected at pH 6.7 in human primary fibroblasts without affecting cell viability.

Lee, Sang Kil; Achieng, Elsie; Maddox, Connie; Chen, Suephy C.; Iuvone, Michael; Fukuhara, Chiaki

2011-01-01

151

Sleep and Circadian Rhythms in Spousally Bereaved Seniors  

PubMed Central

A laboratory study of sleep and circadian rhythms was undertaken in 28 spousally bereaved seniors (?60 yrs) at least four months after the loss event. Measures taken included two nights of polysomnography (second night used), ?36 h of continuous core body temperature monitoring, and four assessments of mood and alertness throughout a day. Preceding the laboratory study, two-week diaries were completed, allowing the assessment of lifestyle regularity using the 17-item Social Rhythm Metric (SRM) and the timing of sleep using the Pittsburgh Sleep Diary (PghSD). Also completed were questionnaires assessing level of grief (Texas Revised Inventory of Grief [TRIG] and Index of Complicated Grief [ICG]), subjective sleep quality (Pittsburgh Sleep Quality Index [PSQI]), morningness-eveningness (Composite Scale of Morningness [CSM]), and clinical interview yielding a Hamilton Depression Rating Scale (HDRS) score. Grief was still present, as indicated by an average TRIG score of about 60. On average, the bereaved seniors habitually slept between ?23:00 and ?06:40 h, achieving ?6 h of sleep with a sleep efficiency of ?80%. They took about 30 min to fall asleep, and had their first REM episode after 75 min. About 20% of their sleep was in Stage REM, and about 3% in Stages 3 or 4 (slow wave sleep). Their mean PSQI score was 6.4. Their circadian temperature rhythms showed the usual classic shape with a trough at ?01:00 h, a fairly steep rise through the morning hours, and a more gradual rise to mid-evening, with an amplitude of ?0.8°C. In terms of lifestyle regularity, the mean regularity (SRM) score was 3.65 (slightly lower than that usually seen in seniors). Mood and alertness showed time-of-day variation with peak alertness in the late morning and peak mood in the afternoon. Correlations between outcome sleep/circadian variables and level of grief (TRIG score) were calculated; there was a slight trend for higher grief to be associated with less time spent asleep (p = 0.07) and reduced alertness at 20:00 h (p = 0.05). Depression score was not correlated with TRIG score (p > 0.20). When subjects were divided into groups by the nature of their late spouse's death (expected/after a long-term chronic illness [n = 18] versus unexpected [n = 10]), no differences emerged in any of the variables. In conclusion, when studied at least four months after the loss event, there appears to be some sleep disruption in spousally bereaved seniors. However, this disruption does not appear to be due to bereavement-related disruptions in the circadian system.

Monk, Timothy H.; Begley, Amy E.; Billy, Bart D.; Fletcher, Mary E.; Germain, Anne; Mazumdar, Sati; Moul, Douglas E.; Shear, M. Katherine; Thompson, Wesley K.; Zarotney, Joette R.

2009-01-01

152

Circadian Sleep-Wake Rhythm of Older Adults with Intellectual Disabilities  

ERIC Educational Resources Information Center

The circadian sleep-wake rhythm changes with aging, resulting in a more fragmented sleep-wake pattern. In individuals with intellectual disabilities (ID), brain structures regulating the sleep-wake rhythm might be affected. The aims of this study were to compare the sleep-wake rhythm of older adults with ID to that of older adults in the general…

Maaskant, Marijke; van de Wouw, Ellen; van Wijck, Ruud; Evenhuis, Heleen M.; Echteld, Michael A.

2013-01-01

153

Alterations in circadian rhythms are associated with increased lipid peroxidation in females with bipolar disorder.  

PubMed

Disturbances in both circadian rhythms and oxidative stress systems have been implicated in the pathophysiology of bipolar disorder (BD), yet no studies have investigated the relationship between these systems in BD. We studied the impact of circadian rhythm disruption on lipid damage in 52 depressed or euthymic BD females, while controlling for age, severity of depressive symptoms and number of psychotropic medications, compared to 30 healthy controls. Circadian rhythm disruption was determined by a self-report measure (Biological Rhythm Interview of Assessment in Neuropsychiatry; BRIAN), which measures behaviours such as sleep, eating patterns, social rhythms and general activity. Malondialdehyde (MDA) levels were measured as a proxy of lipid peroxidation. We also measured the activity of total and extracellular superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). Multiple linear regressions showed that circadian rhythm disturbance was independently associated with increased lipid peroxidation in females with BD (p < 0.05). We found decreased extracellular SOD (p < 0.05), but no differences in total SOD, CAT or GST activity between bipolar females and controls. Circadian rhythms were not associated with lipid peroxidation in healthy controls, where aging was the only significant predictor. These results suggest an interaction between the circadian system and redox metabolism, in that greater disruption in daily rhythms was associated with increased lipid peroxidation in BD only. Antioxidant enzymes have been shown to follow a circadian pattern of expression, and it is possible that disturbance of sleep and daily rhythms experienced in BD may result in decreased antioxidant defence and therefore increased lipid peroxidation. This study provides a basis for further investigation of the links between oxidative stress and circadian rhythms in the neurobiology of BD. PMID:24438530

Cudney, Lauren E; Sassi, Roberto B; Behr, Guilherme A; Streiner, David L; Minuzzi, Luciano; Moreira, Jose C F; Frey, Benicio N

2014-05-01

154

Circadian rhythms on skin function of hairless rats: light and thermic influences.  

PubMed

Circadian rhythms are present in most functions of living beings. We have demonstrated the presence of circadian rhythms in skin variables (transepidermal water loss, TEWL; stratum corneum hydration, SCH; and skin temperature) in hairless rats under different environmental conditions of light and temperature. Circadian rhythms in TEWL and SCH showed mean amplitudes of about 20% and 14% around the mean, respectively, and appeared under light-dark cycles as well as under constant darkness. Environmental temperature was able to override TEWL, but not SCH rhythm, evidencing the dependency of TEWL on the temperature. Mean daily values of TEWL and SCH, and also the amplitude of TEWL rhythm, increased with the age of the animal. Under constant light, situation that induces arrhythmicity in rats, SCH and TEWL were inversely correlated. The results suggest the importance to take into account the functional skin rhythms in research in dermatological sciences. PMID:24499392

Flo, Ana; Díez-Noguera, Antoni; Calpena, Ana C; Cambras, Trinitat

2014-03-01

155

Effect of circadian rhythms on retrieval-induced forgetting.  

PubMed

This study investigated the effects of natural circadian rhythms on retrieval-induced forgetting (RIF; Anderson et al. in J Exp Psychol Learn Mem Cogn 20:1063-1087, 1994). Individuals tested at optimal times (i.e., morning persons tested in the morning and evening persons tested in the evening) showed a significantly greater RIF effect than individuals tested at non-optimal times (i.e., morning persons tested in the evening and evening persons tested in the morning). Thus, the limited quantity of resources available to allocate in the inhibitory activity during non-optimal times produced a significant decrement in RIF. These findings are compatible with the inhibitory account of RIF and with the notion of a resource-demanding process underlying this memory phenomenon. PMID:23836277

Pica, Gennaro; Pierro, Antonio; Kruglanski, Arie W

2014-02-01

156

Phase control of ultradian feeding rhythms in the common vole (Microtus arvalis): the roles of light and the circadian system.  

PubMed

In their ultradian (2- to 3-hr) feeding rhythm, common voles show intraindividual synchrony from day to day, as well as interindividual synchrony between members of the population, even at remote distances. This study addresses the question of how resetting of the ultradian rhythm, a prerequisite for such synchronization, is achieved. Common voles were subjected to short light-dark cycles (1 hr darkness with light varying between 0.7 and 2.5 hr); to T cycles (long light-dark cycles in the circadian range--16 hr darkness and 3-13 hr light); to light pulses (15 min) during different circadian and ultradian phases; and to addition of D2O to the drinking water (25%). Short light-dark cycles and D2O were also applied to voles without circadian rhythmicity, after lesions of the suprachiasmatic nuclei. In these experiments, four hypotheses on synchronization of ultradian rhythmicity were tested: (I) synchronization by a direct response to light; (II) synchronization via the circadian system with multiple triggers, here called "cogs," each controlling a single ultradian feeding bout; and (III and IV) synchronization via the circadian system with a single "cog," which resets an ultradian oscillator and either (III) originates directly from the circadian pacemaker, or (IV) is mediated via the overt circadian activity rhythm. Short light-dark cycles failed to entrain ultradian rhythms, either in circadian-rhythmic or in non-circadian-rhythmic voles; light pulses did not cause phase shifts; and in extreme T cycles no stable phase relationship with light could be demonstrated. Thus, Hypothesis I was rejected. Changes in the circadian period (tau) were generated as aftereffects of light pulses, by entrainment in various T cycles, and by the addition of D2O to the drinking water. These changes in tau did not lead to parallel, let alone proportional, changes in the ultradian period. This excluded Hypothesis II. Both in T-cycle experiments and in the D2O experiments with circadian-rhythmic voles, the phase of ultradian feeding bouts was locked to the end of circadian activity rather than to the most prominent marker of the pacemaker, the onset of circadian activity. This was not expected under Hypothesis III, but was consistent with entrainment via activity (Hypothesis IV). On the basis of these experiments, we conclude that the most likely mechanism of ultradian entrainment is that of a light-insensitive ultradian oscillator, reset every dawn by the termination of the activity phase controlled by the circadian pacemaker, which is itself entrained by the light-dark cycle. Neither in circadian-rhythmic nor in non-circadian-rhythmic voles was the period of the feeding rhythm lengthened by administration of D2O. This insensitivity to deuterium is exceptional among biological rhythms. PMID:8369551

Gerkema, M P; Daan, S; Wilbrink, M; Hop, M W; van der Leest, F

1993-01-01

157

Clock genes show circadian rhythms in salivary glands.  

PubMed

Circadian rhythms are endogenous self-sustained oscillations with 24-hour periods that regulate diverse physiological and metabolic processes through complex gene regulation by "clock" transcription factors. The oral cavity is bathed by saliva, and its amount and content are modified within regular daily intervals. The clock mechanisms that control salivary production remain unclear. Our objective was to evaluate the expression and periodicity of clock genes in salivary glands. Real-time quantitative RT-PCR, in situ hybridization, and immunohistochemistry were performed to show circadian mRNA and protein expression and localization of key clock genes (Bmal1, Clock, Per1, and Per2), ion and aqua channel genes (Ae2a, Car2, and Aqp5), and salivary gland markers. Clock gene mRNAs and clock proteins were found differentially expressed in the serous acini and duct cells of all major salivary glands. The expression levels of clock genes and Aqp5 showed regular oscillatory patterns under both light/dark and complete-dark conditions. Bmla1 overexpression resulted in increased Aqp5 expression levels. Analysis of our data suggests that salivary glands have a peripheral clock mechanism that functions both in normal light/dark conditions and in the absence of light. This finding may increase our understanding of the control mechanisms of salivary content and flow. PMID:22699207

Zheng, L; Seon, Y J; McHugh, J; Papagerakis, S; Papagerakis, P

2012-08-01

158

Sleep and circadian rhythm regulation in early Parkinson disease.  

PubMed

IMPORTANCE Sleep disturbances are recognized as a common nonmotor complaint in Parkinson disease but their etiology is poorly understood. OBJECTIVE To define the sleep and circadian phenotype of patients with early-stage Parkinson disease. DESIGN, SETTING, AND PARTICIPANTS Initial assessment of sleep characteristics in a large population-representative incident Parkinson disease cohort (N=239) at the University of Cambridge, England, followed by further comprehensive case-control sleep assessments in a subgroup of these patients (n=30) and matched controls (n=15). MAIN OUTCOMES AND MEASURES Sleep diagnoses and sleep architecture based on polysomnography studies, actigraphy assessment, and 24-hour analyses of serum cortisol, melatonin, and peripheral clock gene expression (Bmal1, Per2, and Rev-Erb?). RESULTS Subjective sleep complaints were present in almost half of newly diagnosed patients and correlated significantly with poorer quality of life. Patients with Parkinson disease exhibited increased sleep latency (P?=?.04), reduced sleep efficiency (P?=?.008), and reduced rapid eye movement sleep (P?=?.02). In addition, there was a sustained elevation of serum cortisol levels, reduced circulating melatonin levels, and altered Bmal1 expression in patients with Parkinson disease compared with controls. CONCLUSIONS AND RELEVANCE Sleep dysfunction seen in early Parkinson disease may reflect a more fundamental pathology in the molecular clock underlying circadian rhythms. PMID:24687146

Breen, David P; Vuono, Romina; Nawarathna, Upekshani; Fisher, Kate; Shneerson, John M; Reddy, Akhilesh B; Barker, Roger A

2014-05-01

159

Treatment of a Circadian Rhythm Disturbance in a 2-Year-Old Blind Child.  

ERIC Educational Resources Information Center

The use of sleep scheduling and a daytime routine for the treatment of circadian rhythm disorder was found helpful in decreasing a blind 2-year old's nighttime wake periods and daytime sleepiness. (DB)

Mindell, J. A.; And Others

1996-01-01

160

Effects of Abrupt Time Zone Change on Some Circadian Rhythms in Man.  

National Technical Information Service (NTIS)

Changes have been demonstrated in circadian rhythm indices of the cardiovascular system in essentially healthy individuals, in the course of transmeridional flights, particularly when crossing over 9 time zones. The nature of the changes depends on the di...

N. I. Moiseyeva

1976-01-01

161

Circadian rhythms investigated on the cellular and molecular levels.  

PubMed

Investigations on circadian rhythms have markedly advanced our understanding of health and disease with the advent of high-throughput technologies like microarrays and epigenetic profiling. They elucidated the multi-level behaviour of interactive oscillations from molecules to neuronal networks and eventually to processes of learning and memory in an impressive manner. The small-world topology of synchronized firing through neuron-neuron and neuron-glia gap junctions is discussed as a mathematical approach to these intensively studied issues. It has become evident that, apart from some disorders caused by gene mutations, the majority of disorders originating from disturbances of rhythms arise from environmental influences and epigenetic changes. In this context, it was mandatory to think of and devise experiments on temporary scales, which exponentially increased the volumes of data obtained from time-series and rapidly became prohibitive of manual inspection. Therefore, more and more sophisticated mathematical algorithms have been developed to identify rhythmic expression of genes and to find coexpression by their clustering. It is expected that disturbed rhythmic behaviour in mental disorders is reflected in altered oscillatory behaviour of gene expression. PMID:23599242

Gebicke-Haerter, P J; Pildaín, L V; Matthäus, F; Schmitt, A; Falkai, P

2013-05-01

162

Photoperiodic modulation of circadian rhythms in the cricket Gryllus bimaculatus.  

PubMed

The waveform and the free-running period of circadian rhythms in constant conditions are often modulated by preceding lighting conditions. We have examined the modulatory effect of variable length of light phase of a 24h light cycle on the ratio of activity (alpha) and rest phase (rho) as well as on the free-running period of the locomotor rhythm in the cricket Gryllus bimaculatus. When experienced the longer light phases, the alpha/rho-ratio was smaller and the free-running period was shorter. The magnitude of changes in alpha/rho-ratio was dependent on the number of cycles exposed, while the free-running period was changed by a single exposure, suggesting that there are separate regulatory mechanisms for the waveform and the free-running period. The neuronal activity of the optic lobe showed the alpha/rho-ratio changing with the preceding photoperiod. When different photoperiodic conditions were given to each of the two optic lobe pacemakers, the alpha/rho-ratio of a single pacemaker was rather intermediate between those of animals treated with either of the two conditions. These results suggest that the storage of the photoperiodic information occurs at least in part in the optic lobe pacemaker, and that the mutual interaction between the bilateral optic lobe pacemakers is involved in the photoperiodic modulation. PMID:15993131

Koga, Mika; Ushirogawa, Hiroshi; Tomioka, Kenji

2005-06-01

163

Idiopathic chronic sleep onset insomnia in attention-deficit\\/hyperactivity disorder: a circadian rhythm sleep disorder  

Microsoft Academic Search

To investigate whether ADHD-related sleep-onset insomnia (SOI) is a circadian rhythm disorder, we compared actigraphic sleep estimates, the circadian rest-activity rhythm, and dim light melatonin onset (DLMO) in ADHD children having chronic idiopathic SOI with that in ADHD children without sleep problems. Participants were 87 psychotropic-medication-naive children, aged 6 to 12 yrs, with rigorously diagnosed ADHD and SOI (ADHD-SOI) and

Heijden van der K. B; M. G. Smits; Someren van E. J. W; W. B. Gunning

2005-01-01

164

Sleep and circadian rhythms in spousally bereaved seniors.  

PubMed

A laboratory study of sleep and circadian rhythms was undertaken in 28 spousally bereaved seniors (> or =60 yrs) at least four months after the loss event. Measures taken included two nights of polysomnography (second night used), approximately 36 h of continuous core body temperature monitoring, and four assessments of mood and alertness throughout a day. Preceding the laboratory study, two-week diaries were completed, allowing the assessment of lifestyle regularity using the 17-item Social Rhythm Metric (SRM) and the timing of sleep using the Pittsburgh Sleep Diary (PghSD). Also completed were questionnaires assessing level of grief (Texas Revised Inventory of Grief [TRIG] and Index of Complicated Grief [ICG]), subjective sleep quality (Pittsburgh Sleep Quality Index [PSQI]), morningness-eveningness (Composite Scale of Morningness [CSM]), and clinical interview yielding a Hamilton Depression Rating Scale (HDRS) score. Grief was still present, as indicated by an average TRIG score of about 60. On average, the bereaved seniors habitually slept between approximately 23:00 and approximately 06:40 h, achieving approximately 6 h of sleep with a sleep efficiency of approximately 80%. They took about 30 min to fall asleep, and had their first REM episode after 75 min. About 20% of their sleep was in Stage REM, and about 3% in Stages 3 or 4 (slow wave sleep). Their mean PSQI score was 6.4. Their circadian temperature rhythms showed the usual classic shape with a trough at approximately 01:00 h, a fairly steep rise through the morning hours, and a more gradual rise to mid-evening, with an amplitude of approximately 0.8 degrees C. In terms of lifestyle regularity, the mean regularity (SRM) score was 3.65 (slightly lower than that usually seen in seniors). Mood and alertness showed time-of-day variation with peak alertness in the late morning and peak mood in the afternoon. Correlations between outcome sleep/circadian variables and level of grief (TRIG score) were calculated; there was a slight trend for higher grief to be associated with less time spent asleep (p=0.07) and reduced alertness at 20:00 h (p=0.05). Depression score was not correlated with TRIG score (p>0.20). When subjects were divided into groups by the nature of their late spouse's death (expected/after a long-term chronic illness [n=18] versus unexpected [n=10]), no differences emerged in any of the variables. In conclusion, when studied at least four months after the loss event, there appears to be some sleep disruption in spousally bereaved seniors. However, this disruption does not appear to be due to bereavement-related disruptions in the circadian system. PMID:18293151

Monk, Timothy H; Begley, Amy E; Billy, Bart D; Fletcher, Mary E; Germain, Anne; Mazumdar, Sati; Moul, Douglas E; Shear, M Katherine; Thompson, Wesley K; Zarotney, Joette R

2008-02-01

165

Non-Circadian Expression Masking Clock-Driven Weak Transcription Rhythms in U2OS Cells  

PubMed Central

U2OS cells harbor a circadian clock but express only a few rhythmic genes in constant conditions. We identified 3040 binding sites of the circadian regulators BMAL1, CLOCK and CRY1 in the U2OS genome. Most binding sites even in promoters do not correlate with detectable rhythmic transcript levels. Luciferase fusions reveal that the circadian clock supports robust but low amplitude transcription rhythms of representative promoters. However, rhythmic transcription of these potentially clock-controlled genes is masked by non-circadian transcription that overwrites the weaker contribution of the clock in constant conditions. Our data suggest that U2OS cells harbor an intrinsically rather weak circadian oscillator. The oscillator has the potential to regulate a large number of genes. The contribution of circadian versus non-circadian transcription is dependent on the metabolic state of the cell and may determine the apparent complexity of the circadian transcriptome.

Hoffmann, Julia; Symul, Laura; Shostak, Anton; Fischer, Tamas; Naef, Felix; Brunner, Michael

2014-01-01

166

Maternity-related plasticity in circadian rhythms of bumble-bee queens  

PubMed Central

Unlike most animals studied so far in which the activity with no circadian rhythms is pathological or linked to deteriorating performance, worker bees and ants naturally care for their sibling brood around the clock with no apparent ill effects. Here, we tested whether bumble-bee queens that care alone for their first batch of offspring are also capable of a similar chronobiological plasticity. We monitored locomotor activity of Bombus terrestris queens at various life cycle stages, and queens for which we manipulated the presence of brood or removed the ovaries. We found that gynes typically emerged from the pupae with no circadian rhythms, but after several days showed robust rhythms that were not affected by mating or diapauses. Colony-founding queens with brood showed attenuated circadian rhythms, irrespective of the presence of ovaries. By contrast, queens that lost their brood switched again to activity with strong circadian rhythms. The discovery that circadian rhythms in bumble-bee queens are regulated by the life cycle and the presence of brood suggests that plasticity in the circadian clock of bees is ancient and related to maternal behaviour or physiology, and is not a derived trait that evolved with the evolution of the worker caste.

Eban-Rothschild, Ada; Belluci, Selma; Bloch, Guy

2011-01-01

167

Bioluminescence Imaging of Individual Fibroblasts Reveals Persistent, Independently Phased Circadian Rhythms of Clock Gene Expression  

Microsoft Academic Search

Circadian (ca. 24 hr) oscillations in expression of mammalian “clock genes” are found not only in the suprachiasmatic nucleus (SCN), the central circadian pacemaker, but also in peripheral tissues [1]. Under constant conditions in vitro, however, rhythms of peripheral tissue explants [2] or immortalized cells [3] damp partially or completely. It is unknown whether this reflects an inability of peripheral

David K. Welsh; Seung-Hee Yoo; Andrew C. Liu; Joseph S. Takahashi; Steve A. Kay

2004-01-01

168

Inversion of the circadian rhythm of melatonin in the Smith-Magenis syndrome  

Microsoft Academic Search

Objective: The objective was to determine the circadian rhythm of mela- tonin in the Smith-Magenis syndrome (SMS), which causes behavioral problems and sleep disturbance. Study design: Questionnaires, sleep consultations, and sleep diaries were obtained in 20 children with SMS (9 girls, 11 boys aged 4 to 17 years). Actigraphy, electroencephalography, and the circadian variations of plasma melatonin, cortisol, and growth

Marie-Christine de Blois; Bruno Claustrat; Serge Romana; Urs Albrecht; Bruno Delobel; Géraldine Viot; Stanislas Lyonnet; Michel Vekemans; Arnold Munnich

169

Inversion of the circadian rhythm of melatonin in the Smith-Magenis syndrome  

Microsoft Academic Search

Objective: The objective was to determine the circadian rhythm of melatonin in the Smith-Magenis syndrome (SMS), which causes behavioral problems and sleep disturbance. Study design: Questionnaires, sleep consultations, and sleep diaries were obtained in 20 children with SMS (9 girls, 11 boys aged 4 to 17 years). Actigraphy, electroencephalography, and the circadian variations of plasma melatonin, cortisol, and growth hormone

Hélène De Leersnyder; Marie-Christine de Blois; Bruno Claustrat; Serge Romana; Urs Albrecht; Jürgen-Christoph von Kleist-Retzow; Bruno Delobel; Géraldine Viot; Stanislas Lyonnet; Michel Vekemans; Arnold Munnich

2001-01-01

170

Circadian rhythms in mice fed a single daily meal at different stages of lighting regimen  

Microsoft Academic Search

Circadian rhythms in systemic and cellular variables were studied in three groups of mice on different schedules of daily food accessibility: (1) only during the first 4 hours of the 12-hour light span; (2) only during the first 4 hours of the 12-hour dark span; and (3) at all times. The amplitudes of circadian variation in rectal temperature, serum corticosterone,

WALTER NELSON; L Scheving; F Halberg

1975-01-01

171

Circadian-Rhythm Sleep Disorders in Persons Who Are Totally Blind.  

ERIC Educational Resources Information Center

Discusses the diagnosis and management of "non-24-hour sleep-wake syndrome," a form of cyclic insomnia to which people who are totally blind are prone. Covered are incidence and clinical features, formal diagnostic criteria, the biological basis of circadian sleep disorders, circadian rhythms in blind people, pharmacological entrainment, and the…

Sack, R. L.; Blood, M. L.; Hughes, R. J.; Lewy, A. J.

1998-01-01

172

Food-entrained circadian rhythms in rats are insensitive to deuterium oxide  

Microsoft Academic Search

Rats anticipate a scheduled daily meal by entrainment of a circadian pacemaker separate from the light-entrainable circadian pacemaker located in the suprachiasmatic nuclei (SCN). The site and molecular mechanisms of the food-entrainable pacemaker are unknown. The intrinsic period (?) of the SCN pacemaker is significantly lengthened by deuteriation. Sensitivity of food-entrained circadian rhythms to D2O (25% in drinking water) was

Ralph E. Mistlberger; Elliott G. Marchant; Tod E. Kippin

2001-01-01

173

EFFICIENT MU LTISCALE SIMULATION OF CIRCADIAN RHYTHMS USING AUTOMATED PHASE MACROMODELLING TECHNIQUES  

Microsoft Academic Search

Circadian rhythm mechanisms involve multi-scale interactions between endogenous DNA-transcription oscillators. We present the application of efficient, numerically well- conditioned algorithms for abstracting (potentially large) systems of differential equation models of circadian oscillators into compact, accurate phase-only macromodels. We ap- ply and validate our auto-extracted phase macromodelling technique on mammalian and Drosophila circadian systems, obtaining speedups of 9 ? 13× over

SHATAM AGARWAL; JAIJEET ROYCHOWDHURY

174

Peripheral circadian clock for the cuticle deposition rhythm in Drosophila melanogaster  

Microsoft Academic Search

Insect endocuticle thickens after adult emergence by daily alternating deposition of two chitin layers with different orientation. Although the cuticle deposition rhythm is known to be controlled by a circadian clock in many insects, the site of the driving clock, the photoreceptor for entrainment, and the oscillatory mechanism remain elusive. Here, we show that the cuticle deposition rhythm is regulated

Chihiro Ito; Shin G. Goto; Sakiko Shiga; Kenji Tomioka; Hideharu Numata

2008-01-01

175

A rapid circadian rhythm of carbon-dioxide metabolism in Bryophyllum fedtschenkoi  

Microsoft Academic Search

Leaves of Bryophyllum fedtschenkoi Hamet et Perrier maintained in a stream of normal air and at 15° C exhibit a circadian rhythm of CO2 uptake in continuous light but not in continuous darkness. The rhythm is unusual in that it persists for at least 10 d, and has a short period of approximately 18 h. The mechanism by which this

Malcolm B. Wilkins

1984-01-01

176

Circadian and Ultradian Rhythm and Leptin Pulsatility in Adult GH Deficiency: Effects of GH Replacement  

Microsoft Academic Search

Leptin contributes to the regulation of body weight in healthy individuals and is secreted by adipocytes in a diurnal pattern, with superimposed pulsatility. The circulating leptin concen- tration is increased in both normally obese and untreated adult GH deficiency, a syndrome characterized by increased adiposity. Leptin circadian rhythm is preserved in adult GH deficiency patients; however, an ultradian rhythm and

AFTAB M. AHMAD; RUSTOM GUZDER; A. MICHAEL WALLACE; JOEGI THOMAS; WILLIAM D. FRASER; JITEN P. VORA

2010-01-01

177

Entrainment of the circadian activity rhythm of a lizard to melatonin injections.  

PubMed

The circadian activity rhythms of lizards (Sceloporus occidentalis) can be entrained (synchronized) to a period of 24 hr by melatonin injections given every other day at the same time of day, but not by saline injections. The activity onsets of the entrained lizards exhibited two preferred phase-relationships (approximately 165 degrees and approximately 30 degrees) with the time of melatonin injections with the 30 degree phase only rarely observed. These results suggest that endogenous rhythms of melatonin secretion (i.e., from the pineal organ) may be involved in synchronizing circadian oscillations within the lizard's multioscillator circadian system. PMID:4070395

Underwood, H; Harless, M

1985-08-01

178

Inhibition of the circadian rhythm of CO 2 metabolism in Bryophyllum leaves by cycloheximide and dinitrophenol  

Microsoft Academic Search

The circadian rhythm of CO2 output in darkened leaves of Bryophyllum fedtschenkoi R. Hamet and Perrier can be inhibited by cycloheximide (?10-6 mol) and 2,4-dinitrophenol (?10-5 mol) applied via the transpiration stream. After having been suppressed by 10-6 M cycloheximide, the rhythm can be reinitiated with a 12-h exposure to light. Experiments using 14CO2 show that cycloheximide abolishes the rhythm

Irene C. Bollig; Malcolm B. Wilkins

1979-01-01

179

Circadian Rhythms Confer a Higher Level of Fitness to Arabidopsis Plants1  

PubMed Central

Circadian rhythms have been demonstrated in organisms across the taxonomic spectrum. In view of their widespread occurrence, the adaptive significance of these rhythms is of interest. We have previously shown that constitutive expression of the CCA1 (CIRCADIAN CLOCK ASSOCIATED 1) gene in Arabidopsis plants (CCA1-ox) results in loss of circadian rhythmicity. Here, we demonstrate that these CCA1-ox plants retain the ability to respond to diurnal changes in light. Thus, transcript levels of several circadian-regulated genes, as well as CCA1 itself and the closely related LHY, oscillate robustly if CCA1-ox plants are grown under diurnal conditions. However, in contrast with wild-type plants in which transcript levels change in anticipation of the dark/light transitions, the CCA1-ox plants have lost the ability to anticipate this daily change in their environment. We have used CCA1-ox lines to examine the effects of loss of circadian regulation on the fitness of an organism. CCA1-ox plants flowered later, especially under long-day conditions, and were less viable under very short-day conditions than their wild-type counterparts. In addition, we demonstrate that two other circadian rhythm mutants, LHY-ox and elf3, have low-viability phenotypes. Our findings demonstrate the adaptive advantage of circadian rhythms in Arabidopsis.

Green, Rachel M.; Tingay, Sonia; Wang, Zhi-Yong; Tobin, Elaine M.

2002-01-01

180

Effects of simian immunodeficiency virus on the circadian rhythms of body temperature and gross locomotor activity  

PubMed Central

In monkeys infected with simian immunodeficiency virus (SIV), changes in body temperature and locomotor activity occur after the acute retroviral syndrome stage of the disease. However, alterations to the circadian rhythm of these factors in SIV-infected monkeys have not been reported. To determine whether the circadian rhythm of body temperature and locomotor activity are disrupted during SIV infection, we analyzed the temperature and activity patterns of SIV-infected monkeys through different stages of the disease, progressing to SIV encephalitis by using the cosinor model for circadian oscillation. We found that SIV infection resulted in significant impairments of the amplitude and mean of the circadian rhythm of body temperature and activity and in the acrophase of the circadian rhythm for temperature. These alterations were not related to changes observed in the acute febrile response induced after viral inoculation. In animals killed once marked circadian anomalies were evident, microglia infiltration and macrophage accumulation in the hypothalamus were observed. Together, these results clearly demonstrate that SIV infection compromises aspects of circadian regulation in monkeys, with important implications for physiological functions, including cognition, in HIV-infected individuals.

Huitron-Resendiz, Salvador; Marcondes, Maria Cecilia G.; Flynn, Claudia T.; Lanigan, Caroline M. S.; Fox, Howard S.

2007-01-01

181

[Subjective wellbeing of shift workers in relation to individual characteristics of circadian rhythm].  

PubMed

With a goal to test the influence of individual traits of circadian rhythms on the tolerance of shiftwork a circadian questionnaire has been developed with the method of factors analysis. There are two scales in the final form of the questionnaire representing two chronobiological characteristics: morningness - eveningsness (circadian phase-position) and flexibility of the sleep-wake-rhythm. Sex- and age-norms exist for the two scales. Reliability and validity have been demonstrated. The results of an epidemiological study shows that the hypothesis of better adjustment to shiftwork of evening-types can not be verified. A better predictor of tolerance to shift work in terms of wellbeing seems to be the individual circadian trait flexibility of sleep-wake-rhythm. PMID:2336856

Röhner, J; Kaufmann, O; Schurig, H U

1990-03-01

182

Comparison of hormone and electrolyte circadian rhythms in male and female humans  

NASA Technical Reports Server (NTRS)

Circadian rhythm characteristics in healthy male and female humans were studied at 4-hour intervals for urine volume, cortisol, 5-hydroxyindoleacetic acid (5-HIAA), Na, K, Na/K ratios in the urine, as well as plasma cortisol. While plasma and urinary cortisol rhythms were very similar in both sexes, the described rhythms in urine volume, electrolyte, and 5-HIAA excretion differ for the two sexes. The results suggest that sex differences exist in the circadian patterns of important hormone and metabolic functions and that the internal synchrony of circadian rhythms differs for the two sexes. The results seem to indicate that the rhythmical secretion of cortisol does not account for the pattern of Na and K excretion.

Vernikos-Danellis, J.; Winget, C. M.; Goodwin, A. E.; Reilly, T.

1977-01-01

183

Circadian rhythm in olfactory response in the antennae controlled by the optic lobe in the cockroach.  

PubMed

The olfactory response in antennae of the cockroach, Leucophaea maderae, was investigated by measuring electroantennograms (EAGs) in restrained animals. The amplitude of the EAG response to pulses of ethyl acetate, octanol, or fenchone, exhibited a robust, light entrained, circadian rhythm that persisted at least 14 days in constant darkness. Dilution-response curves measured at the peak and trough of the rhythm indicated there was a 10-fold change in sensitivity. The EAG rhythm was abolished by severing the optic tracts, while entrainment was abolished by ablation of the compound eyes. The results indicate that the circadian system modulates olfactory sensitivity in the antennae and that the rhythm is driven by a circadian pacemaker in the optic lobes that is entrained by photoreceptors in the compound eyes. PMID:12837322

Page, Terry L; Koelling, Erin

2003-07-01

184

Circadian rhythm of autophagy and light responses of autophagy and disk-shedding in the rat retina  

Microsoft Academic Search

The rhythm of autophagic degradation (AV) in visual cell inner segments shows circadian characteristics: it persists under constant conditions of continuous darkness (DD) and continuous light (LL) and can be reentrained to phase-shifts of the light-dark (LD) cycle. However, unlike the rhythm of disk-shedding and many other circadian rhythms, the rhythm of AV persists with a distinct peak even after

C. Remé; B. Aeberhard; M. Schoch

1985-01-01

185

Circadian rhythm of aldosterone in dairy cattle during the summer  

NASA Astrophysics Data System (ADS)

Twelve Holstein heifers, pregnant from 120 150 days were used to study the circadian rhythm of aldosterone, cortisol, progesterone, sodium and potassium in dairy cattle during the summer in Louisiana. Cortisol was not significantly influenced by time (time 1 = 06.00 h). Aldosterone, sodium, potassium and progesterone changed significantly (P<.01) with time. Aldosterone peaked (116.5±17.2 pg/ml) at 08.00 h and then generally declined to 16.00 h (26.7±2.0 pg/ml). Sodium generally increased from 06.00 h (320.1±7.3 mg%) to 18.00 h (377.9±6.1 mg%), and then declined. Potassium generally increased from 06.00 h (20.9±0.5 mg%) to 22.00 h (23.0±0.3 mg%). Progesterone generally increased from 07.00 h (2.8±0.4 mg/ml) to 24.00 h (7.5±1.4 mg/ml). Aldosterone was significantly related to temperature associated with the time of the day samples were taken (r = 0.66, P<.02).

Aranas, T. J.; Roussel, J. D.; Seybt, S. H.

1987-09-01

186

Robust Circadian Rhythms of Gene Expression in Brassica rapa Tissue Culture1[W][OA  

PubMed Central

Circadian clocks provide temporal coordination by synchronizing internal biological processes with daily environmental cycles. To date, study of the plant circadian clock has emphasized Arabidopsis (Arabidopsis thaliana) as a model, but it is important to determine the extent to which this model applies in other species. Accordingly, we have investigated circadian clock function in Brassica rapa. In Arabidopsis, analysis of gene expression in transgenic plants in which luciferase activity is expressed from clock-regulated promoters has proven a useful tool, although technical challenges associated with the regeneration of transgenic plants has hindered the implementation of this powerful tool in B. rapa. The circadian clock is cell autonomous, and rhythmicity has been shown to persist in tissue culture from a number of species. We have established a transgenic B. rapa tissue culture system to allow the facile measurement and manipulation of clock function. We demonstrate circadian rhythms in the expression of several promoter:LUC reporters in explant-induced tissue culture of B. rapa. These rhythms are temperature compensated and are reset by light and temperature pulses. We observe a strong positive correlation in period length between the tissue culture rhythm in gene expression and the seedling rhythm in cotyledon movement, indicating that the circadian clock in B. rapa tissue culture provides a good model for the clock in planta.

Xu, Xiaodong; Xie, Qiguang; McClung, C. Robertson

2010-01-01

187

Replication of cortisol circadian rhythm: new advances in hydrocortisone replacement therapy.  

PubMed

Cortisol has one of the most distinct and fascinating circadian rhythms in human physiology. This is regulated by the central clock located in the suprachiasmatic nucleus of the hypothalamus. It has been suggested that cortisol acts as a secondary messenger between central and peripheral clocks, hence its importance in the synchronization of body circadian rhythms. Conventional immediate-release hydrocortisone, either at twice- or thrice-daily doses, is not capable of replicating physiological cortisol circadian rhythm and patients with adrenal insufficiency or congenital adrenal hyperplasia still suffer from a poor quality of life and increased mortality. Novel treatments for replacement therapy are therefore essential. Proof-of-concept studies using hydrocortisone infusions suggest that the circadian delivery of hydrocortisone may improve biochemical control and life quality in patients lacking cortisol with an impaired cortisol rhythm. Recently oral formulations of modified-release hydrocortisone are being developed and it has been shown that it is possible to replicate cortisol circadian rhythm and also achieve better control of morning androgen levels. These new drug therapies are promising and potentially offer a more effective treatment with less adverse effects. Definite improvements clearly need to be established in future clinical trials. PMID:23148157

Chan, Sharon; Debono, Miguel

2010-06-01

188

Wheel-running activity modulates circadian organization and the daily rhythm of eating behavior  

PubMed Central

Consumption of high-fat diet acutely alters the daily rhythm of eating behavior and circadian organization (the phase relationship between oscillators in central and peripheral tissues) in mice. Voluntary wheel-running activity counteracts the obesogenic effects of high-fat diet and also modulates circadian rhythms in mice. In this study, we sought to determine whether voluntary wheel-running activity could prevent the proximate effects of high-fat diet consumption on circadian organization and behavioral rhythms in mice. Mice were housed with locked or freely rotating running wheels and fed chow or high-fat diet for 1 week and rhythms of locomotor activity, eating behavior, and molecular timekeeping (PERIOD2::LUCIFERASE luminescence rhythms) in ex vivo tissues were measured. Wheel-running activity delayed the phase of the liver rhythm by 4 h in both chow- and high-fat diet-fed mice. The delayed liver phase was specific to wheel-running activity since an enriched environment without the running wheel did not alter the phase of the liver rhythm. In addition, wheel-running activity modulated the effect of high-fat diet consumption on the daily rhythm of eating behavior. While high-fat diet consumption caused eating events to be more evenly dispersed across the 24 h-day in both locked-wheel and wheel-running mice, the effect of high-fat diet was much less pronounced in wheel-running mice. Together these data demonstrate that wheel-running activity is a salient factor that modulates liver phase and eating behavior rhythms in both chow- and high-fat-diet fed mice. Wheel-running activity in mice is both a source of exercise and a self-motivating, rewarding behavior. Understanding the putative reward-related mechanisms whereby wheel-running activity alters circadian rhythms could have implications for human obesity since palatable food and exercise may modulate similar reward circuits.

Pendergast, Julie S.; Branecky, Katrina L.; Huang, Roya; Niswender, Kevin D.; Yamazaki, Shin

2014-01-01

189

Melanopsin resets circadian rhythms in cells by inducing clock gene Period1  

NASA Astrophysics Data System (ADS)

The biochemical, physiological and behavioral processes are under the control of internal clocks with the period of approximately 24 hr, circadian rhythms. The expression of clock gene Period1 (Per1) oscillates autonomously in cells and is induced immediately after a light pulse. Per1 is an indispensable member of the central clock system to maintain the autonomous oscillator and synchronize environmental light cycle. Per1 expression could be detected by Per1?luc and Per1?GFP plasmid DNA in which firefly luciferase and Green Fluorescence Protein were rhythmically expressed under the control of the mouse Per1 promoter in order to monitor mammalian circadian rhythms. Membrane protein, MELANOPSIN is activated by blue light in the morning on the retina and lead to signals transduction to induce Per1 expression and to reset the phase of circadian rhythms. In this report Per1 induction was measured by reporter signal assay in Per1?luc and Per1?GFP fibroblast cell at the input process of circadian rhythms. To the result all process to reset the rhythms by Melanopsin is completed in single cell like in the retina projected to the central clock in the brain. Moreover, the phase of circadian rhythm in Per1?luc cells is synchronized by photo-activated Melanopsin, because the definite peak of luciferase activity in one dish was found one day after light illumination. That is an available means that physiological circadian rhythms could be real-time monitor as calculable reporter (bioluminescent and fluorescent) chronological signal in both single and groups of cells.

Yamashita, Shuhei; Uehara, Tomoe; Matsuo, Minako; Kikuchi, Yo; Numano, Rika

2014-02-01

190

Circadian rhythm in the biting behaviour of a mosquito Armigeres subalbatus (Coquillett).  

PubMed

The crepuscular biting rhythm of A. subalbatus has been found to be a genuine circadian rhythm. When the entrained biting rhythm is allowed to freerun in constant darkness (DD) and continuous illumination (LL), it persists in DD (tau = 24.36 hr) and also in LL of ca. 0.1 1x (tau-23.82 hr) thus deviating from the strict 24 hr periodicity of the geophysical day. The biting rhythm becomes arrhythmic in LL of 1.0, 10, 0.4, 4, 40 lx even the first cycle damping away. PMID:7916332

Pandian, R S

1994-04-01

191

Circadian rhythm of homocysteine is hCLOCK genotype dependent.  

PubMed

Homocysteine (Hcy) is known to be a prognostic marker for neurological, cardiovascular and cerebrovascular diseases and several other pathophysiological conditions. A sudden surge in Hcy can increase cardiovascular events. Hemodynamic modulations are known to be associated with individual's chronotype. Therefore, precise monitoring of Hcy is crucial for evaluating its impact on risk. The aim of the present study was to investigate the rhythmicity of Hcy under controlled dietary conditions and whether this rhythmicity is under the genetic control of circadian rhythm. Five subjects were selected from 200 Malayalam speaking healthy ethnic individuals who were screened for functionally critical variants of MTHFR and hCLOCK genes. MTHFR is the rate-limiting enzyme in the methionine cycle and critical for regulating Hcy levels while hCLOCK is a critical gene responsible in regulating the day and night cycles. Rhythmicity in Hcy levels were observed in all the subjects with a consensus on a morning nadir and an evening peak. Gender specific stratification of Hcy levels were observed among similar genotypes of MTHFR and hCLOCK genes. Variations from the conventional rhythmicity of Hcy were observed among similar genotypes of MTHFR and dissimilar hCLOCK genotypes. A reduced plasma Hcy in hCLOCK rs1801260 CC genotype individuals were observed in contrast to CT genotype individuals. The study tends to suggest that Hcy and body time are genetically interdependent and throws light on some of the previously unexplained reasons for variability in Hcy levels. A population specific variation of MTHFR and hCLOCK genes also highlights ethnicity specific risk management. PMID:24510388

Paul, Basil; Saradalekshmi, K R; Alex, Ann Mary; Banerjee, Moinak

2014-06-01

192

Controlling circadian rhythms by dark-pulse perturbations in Arabidopsis thaliana.  

PubMed

Plant circadian systems are composed of a large number of self-sustained cellular circadian oscillators. Although the light-dark signal in the natural environment is known to be the most powerful Zeitgeber for the entrainment of cellular oscillators, its effect is too strong to control the plant rhythm into various forms of synchrony. Here, we show that the application of pulse perturbations, i.e., short-term injections of darkness under constant light, provides a novel technique for controlling the synchronized behavior of plant rhythm in Arabidopsis thaliana. By destroying the synchronized cellular activities, circadian singularity was experimentally induced. The present technique is based upon the theory of phase oscillators, which does not require prior knowledge of the detailed dynamics of the plant system but only knowledge of its phase and amplitude responses to the pulse perturbation. Our approach can be applied to diverse problems of controlling biological rhythms in living systems. PMID:23524981

Fukuda, Hirokazu; Murase, Haruhiko; Tokuda, Isao T

2013-01-01

193

The possible long-term effects of early-life circadian rhythm disturbance on social behavior.  

PubMed

Sleep loss impairs brain function. As late sleep onset can reduce sleep, this sleep/circadian rhythm disturbance may cause brain impairment. Specific data on the long-term effects of sleep/circadian rhythm disturbance on subsequent brain function are lacking. Japan, a sleep-deprived society from infancy to adulthood, provides an ideal platform to investigate the association of these disturbances in early life with subsequent functioning. In this article, several current problematic behaviors among youth in Japan (dropping out from high school, school absenteeism, early resignation from employment, and suicide) are discussed in relation to early life sleep/circadian rhythm patterns. We hypothesize that daily habits of modern society during early stages of life produce unfavorable effects on brain function resulting in problematic behaviors in subsequent years. PMID:24902476

Kohyama, Jun

2014-07-01

194

[Circadian rhythms and temperature homeostasis in monkeys during a flight on the Kosmos 1514 biosatellite  

NASA Technical Reports Server (NTRS)

In the course of a 5-day space flight of two rhesus-monkeys the following parameters were recorded at an interval of 16 min: core body temperature (Tc), skin temperature (Ts), and motor activity (MA). The telemetric Tc sensor was implanted subcutaneously in the right axilla, Ts thermistor was attached to the right ankle, and the MA piezotape was fixed to the inner side of the vest. Circadian rhythms of Tc varied with a period of 24 hours in one monkey and 25 hours in the other. The daily Tc decreased on the average by 0.5 degrees C, Ts fell immediately after launch and remained close to the lower limit throughout the flight. The Ts amplitude decreased 5-fold. Phases of the circadian rhythms of Ts changed and circadian rhythms of MA remained unchanged and equal to 24 hours.

Klimovitskui, V. Ia; Alpatov, A. M.; Salzman, F. M.; Fuller, C. A.; Moore-Ede, M. S.

1987-01-01

195

Controlling Circadian Rhythms by Dark-Pulse Perturbations in Arabidopsis thaliana  

PubMed Central

Plant circadian systems are composed of a large number of self-sustained cellular circadian oscillators. Although the light-dark signal in the natural environment is known to be the most powerful Zeitgeber for the entrainment of cellular oscillators, its effect is too strong to control the plant rhythm into various forms of synchrony. Here, we show that the application of pulse perturbations, i.e., short-term injections of darkness under constant light, provides a novel technique for controlling the synchronized behavior of plant rhythm in Arabidopsis thaliana. By destroying the synchronized cellular activities, circadian singularity was experimentally induced. The present technique is based upon the theory of phase oscillators, which does not require prior knowledge of the detailed dynamics of the plant system but only knowledge of its phase and amplitude responses to the pulse perturbation. Our approach can be applied to diverse problems of controlling biological rhythms in living systems.

Fukuda, Hirokazu; Murase, Haruhiko; Tokuda, Isao T.

2013-01-01

196

Adaptation of sleep and circadian rhythms to the Antarctic summer - A question of zeitgeber strength  

NASA Technical Reports Server (NTRS)

Adaptation of sleep and circadian rhythms was examined in three temperate zone dwellers arriving in Antarctica during summer. Rectal temperature, wrist activity, and heart rate were monitored continuously, sleep timing and quality noted on awakening, and mood and fatigue rated every 2 h while awake. Sleep was poorer in 2/3 subjects in Antarctica, where all subjects reported more difficulty rising. Sleep occurred at the same clock times in New Zealand and Antarctica, however, the rhythms of temperature, activity, and heart rate underwent a delay of about of 2 h. The subject with the most Antarctic experience had the least difficulty adapting to sleeping during constant daylight. The subject with the most delayed circadian rhythms had the most difficulty. The delay in the circadian system with respect to sleep and clock time is hypothesized to be due to differences in zeitgeber strength and/or zeitgeber exposure between Antarctica and New Zealand.

Gander, Philippa H.; Macdonald, John A.; Montgomery, John C.; Paulin, Michael G.

1991-01-01

197

Adaptation of sleep and circadian rhythms to the Antarctic summer: a question of zeitgeber strength.  

PubMed

Adaptation of sleep and circadian rhythms was examined in three temperate zone dwellers arriving in Antarctica during summer. Rectal temperature, wrist activity, and heart rate were monitored continuously, sleep timing and quality noted on awakening, and mood and fatigue rated every 2 h while awake. Sleep was poorer in 2/3 subjects in Antarctica, where all subjects reported more difficulty rising. Sleep occurred at the same clock times in New Zealand and Antarctica, however, the rhythms of temperature, activity, and heart rate underwent a delay of about 2 h. The subject with the most Antarctic experience had the least difficulty adapting to sleeping during constant daylight. The subject with the most delayed circadian rhythms had the most difficulty. The delay in the circadian system with respect to sleep and clock time is hypothesized to be due to differences in zeitgeber strength and/or zeitgeber exposure between Antarctica and New Zealand. PMID:1741714

Gander, P H; Macdonald, J A; Montgomery, J C; Paulin, M G

1991-11-01

198

Circadian rhythms and mood: Opportunities for multi-level analyses in genomics and neuroscience  

PubMed Central

In the healthy state, both circadian rhythm and mood are stable against perturbations, yet they are capable of adjusting to altered internal cues or ongoing changes in external conditions. The dual demands of stability and flexibility are met by the collective properties of complex neural networks. Disruption of this balance underlies both circadian rhythm abnormality and mood disorders. However, we do not fully understand the network properties that govern the crosstalk between the circadian system and mood regulation. This puzzle reflects a challenge at the center of neurobiology, and its solution requires the successful integration of existing data across all levels of neural organization, from molecules, cells, circuits, network dynamics, to integrated mental function. This essay discusses several open questions confronting the cross-level synthesis, and proposes that circadian regulation, and its role in mood, stands as a uniquely tractable system to study the causal mechanisms of neural adaptation.

Li, Jun Z

2014-01-01

199

Self-arrangement of cellular circadian rhythms through phase-resetting in plant roots  

NASA Astrophysics Data System (ADS)

We discovered a striped pattern of gene expression with circadian rhythms in growing plant roots using bioluminescent imaging of gene expression. Our experimental analysis revealed that the stripe wave in the bioluminescent image originated at the root tip and was caused by a continuous phase resetting of circadian oscillations. Some complex stripe waves containing arrhythmic regions were also observed. We succeeded in describing the formation mechanisms of these patterns using a growing phase oscillator network with a phase-resetting boundary condition.

Fukuda, Hirokazu; Ukai, Kazuya; Oyama, Tokitaka

2012-10-01

200

Timekeeping in the honey bee colony: integration of circadian rhythms and division of labor  

Microsoft Academic Search

The daily patterns of task performance in honey bee colonies during behavioral development were studied to determine the\\u000a role of circadian rhythmicity in age-related division of labor. Although it is well known that foragers exhibit robust circadian\\u000a patterns of activity in both field and laboratory settings, we report that many in-hive tasks are not allocated according\\u000a to a daily rhythm

Darrell Moore; Jennifer E. Angel; Iain M. Cheeseman; Susan E. Fahrbach; Gene E. Robinson

1998-01-01

201

Long-Lasting Effects of Sepsis on Circadian Rhythms in the Mouse  

PubMed Central

Daily patterns of activity and physiology are termed circadian rhythms and are driven primarily by an endogenous biological timekeeping system, with the master clock located in the suprachiasmatic nucleus. Previous studies have indicated reciprocal relationships between the circadian and the immune systems, although to date there have been only limited explorations of the long-term modulation of the circadian system by immune challenge, and it is to this question that we addressed ourselves in the current study. Sepsis was induced by peripheral treatment with lipopolysaccharide (5 mg/kg) and circadian rhythms were monitored following recovery. The basic parameters of circadian rhythmicity (free-running period and rhythm amplitude, entrainment to a light/dark cycle) were unaltered in post-septic animals compared to controls. Animals previously treated with LPS showed accelerated re-entrainment to a 6 hour advance of the light/dark cycle, and showed larger phase advances induced by photic stimulation in the late night phase. Photic induction of the immediate early genes c-FOS, EGR-1 and ARC was not altered, and neither was phase-shifting in response to treatment with the 5-HT-1a/7 agonist 8-OH-DPAT. Circadian expression of the clock gene product PER2 was altered in the suprachiasmatic nucleus of post-septic animals, and PER1 and PER2 expression patterns were altered also in the hippocampus. Examination of the suprachiasmatic nucleus 3 months after treatment with LPS showed persistent upregulation of the microglial markers CD-11b and F4/80, but no changes in the expression of various neuropeptides, cytokines, and intracellular signallers. The effects of sepsis on circadian rhythms does not seem to be driven by cell death, as 24 hours after LPS treatment there was no evidence for apoptosis in the suprachiasmatic nucleus as judged by TUNEL and cleaved-caspase 3 staining. Overall these data provide novel insight into how septic shock exerts chronic effects on the mammalian circadian system.

O'Callaghan, Emma K.; Anderson, Sean T.; Moynagh, Paul N.; Coogan, Andrew N.

2012-01-01

202

The Circadian Rhythm of Salivary Cortisol in Growing Pigs: Effects of Age, Gender, and Stress  

Microsoft Academic Search

Ruis, M. A. W., J. H. A. Te Brake, B. Engel, E. D. Ekkel, W. G. Buist, H. J. Blokhuis, J. M. Koolhaas. The circadian rhythm of salivary cortisol in growing pigs: effects of age, gender and stress. Physiol Behav 62(3) 623–630, 1997.—This experiment was designed to examine circadian rhythmicity of cortisol in saliva of growing pigs, in relation to

Marko A. W. Ruis; Joop H. A. Te Brake; Bas Engel; E. Dinand Ekkel; Willem G. Buist; Harry J. Blokhuis; Jaap M. Koolhaas

1997-01-01

203

Sleep and Circadian Rhythm Abnormalities in the Pathophysiology of Bipolar Disorder  

Microsoft Academic Search

\\u000a Among other factors, bipolar disorder is characterized by disturbances in sleep and biological rhythms that typically cycle\\u000a over a 24-h, or circadian period. Indeed, almost all of the functions that constitute symptoms of depression and mania (changes\\u000a in mood, energy, sleep, interest, appetite, capacity for concentration, etc.) show relatively regular variation over the circadian\\u000a period. Thus, it would appear logical

Jessica Levenson; Ellen Frank

204

Effects of estrogen replacement therapy on the circadian rhythms of serum cortisol and body temperature in postmenopausal women  

Microsoft Academic Search

Estrogen replacement therapy (ERT) seems to enhance longevity in women. Both gender and aging have been shown to influence the regulation of circadian rhythms, yet little is known about the effect of ERT on circadian regulation. The aim of this study was to determine the effects of ERT (oral conjugated estrogen: Premarin®, 0.625 mg) for 6–8 weeks on circadian serum

Adalsteinn Gudmundsson; Brian Goodman; Stephanie Lent; Steven Barczi; Ana Grace; Lisa Boyle; William B Ershler; Molly Carnes

1999-01-01

205

Circadian Rhythm Hypotheses of Mixed Features, Antidepressant Treatment Resistance, and Manic Switching in Bipolar Disorder  

PubMed Central

Numerous hypotheses have been put forth over the years to explain the development of bipolar disorder. Of these, circadian rhythm hypotheses have gained much importance of late. While the hypothalamus-pituitary-adrenal (HPA) axis hyperactivation hypothesis and the monoamine hypothesis somewhat explain the pathogenic mechanism of depression, they do not provide an explanation for the development of mania/hypomania. Interestingly, all patients with bipolar disorder display significant disruption of circadian rhythms and sleep/wake cycles throughout their mood cycles. Indeed, mice carrying the Clock gene mutation exhibit an overall behavioral profile that is similar to human mania, including hyperactivity, decreased sleep, lowered depression-like behavior, and lower anxiety. It was recently reported that monoamine signaling is in fact regulated by the circadian system. Thus, circadian rhythm instability, imposed on the dysregulation of HPA axis and monoamine system, may in turn increase individual susceptibility for switching from depression to mania/hypomania. In addition to addressing the pathophysiologic mechanism underlying the manic switch, circadian rhythm hypotheses can explain other bipolar disorder-related phenomena such as treatment resistant depression and mixed features.

Son, Gi-Hoon; Geum, Dongho

2013-01-01

206

Circadian rhythm of leaf movement in Capsicum annuum observed during centrifugation  

NASA Technical Reports Server (NTRS)

Plant circadian rhythms of leaf movement in seedlings of the pepper plant (Capsicum annuum L., var. Yolo Wonder) were observed at different g-levels by means of a centrifuge. Except for the chronically imposed g-force all environmental conditions to which the plants were exposed were held constant. The circadian period, rate of change of amplitude of successive oscillations, symmetry of the cycles, and phase of the rhythm all were found not to be significantly correlated with the magnitude of the sustained g-force.

Chapman, D. K.; Brown, A. H.; Dahl, A. O.

1975-01-01

207

Dim Light at Night Disrupts Molecular Circadian Rhythms and Affects Metabolism  

PubMed Central

With the exception of high latitudes, life has evolved under bright days and dark nights. Most organisms have developed endogenously driven circadian rhythms which are synchronized to this daily light/dark cycle. In recent years, humans have shifted away from the naturally occurring solar light cycle in favor of artificial and sometimes irregular light schedules produced by electrical lighting. Exposure to unnatural light cycles is increasingly associated with obesity and metabolic syndrome; however the means by which environmental lighting alters metabolism are poorly understood. Thus, we exposed mice to nighttime light and investigated changes in the circadian system and body weight. Here we report that exposure to ecologically relevant levels of dim (5 lux) light at night attenuate core circadian clock rhythms in the SCN at both the gene and protein level. Moreover, circadian clock rhythms were perturbed in the liver by nighttime light exposure. Changes in the circadian clock were associated with temporal alterations in feeding behavior and increased weight gain. These results are significant because they provide mechanistic evidence for how mild changes in environmental lighting can alter circadian and metabolic function.

Fonken, Laura K.; Aubrecht, Taryn G.; Melendez-Fernandez, O. Hecmarie; Weil, Zachary M.; Nelson, Randy J.

2014-01-01

208

Role of p53 in the entrainment of mammalian circadian behavior rhythms.  

PubMed

p53 protein plays a role for control of cell proliferation and the induction of apoptosis in normal cells. However, its role in the circadian rhythms that control many physiological functions including locomotor behavior remains unknown. The present study examined the locomotors activity rhythms of mice which have homozygous mutations of p53 gene. The period of drinking activity rhythms in p53 knockout (p53 KO) mice became unstable under constant dark. Light pulse causes a big phase shifts at CT15.5-17, when p53 mRNA expression peaks in the suprachiasmatic nucleus (SCN). Furthermore, photic entrainment of p53 KO mice is unusual under light-dark conditions. These findings suggest that p53 is involved in entrainment of the circadian behavioral rhythm. PMID:24698115

Hamada, Toshiyuki; Niki, Tomoko; Ishida, Norio

2014-05-01

209

Cortisol-mediated synchronization of circadian rhythm in urinary potassium excretion  

NASA Technical Reports Server (NTRS)

Conscious chair-acclimatized squirrel monkeys (Saimiri sciureus) studied with lights on (600 lx) from 0800 to 2000 hr daily (LD 12:12) display a prominent circadian rhythm in renal potassium excretion. The characteristics of this rhythm were reproduced in adrenalectomized monkeys by infusing 5 mg cortisol and 0.001 mg aldosterone, or 5 mg cortisol alone, between 0800 and 0900 kr daily. When the timing of cortisol administration (with or without aldosterone) was phase-delayed by 8 hr, the urinary potassium rhythm resynchronized by 80% of the cortisol phase shift, but only after a transient response lasting 3-4 days. With the same daily dose of adrenal steroids given as a continuous infusion throughout each 24 hr, urinary potassium excretion showed free-running oscillations no longer synchronized to the light-dark cycle. These results indicate that the circadian rhythm of plasma cortisol concentration acts as an internal mediator in the circadian timing system, synchronizing a potentially autonomous oscillation in renal potassium excretion to environmental time cues and to other circadian rhythms within the animal.

Moore-Ede, M. C.; Schmelzer, W. S.; Kass, D. A.; Herd, J. A.

1977-01-01

210

Constant light disrupts the circadian rhythm of steroidogenic proteins in the rat adrenal gland.  

PubMed

The circadian rhythm of corticosterone (CORT) secretion from the adrenal cortex is regulated by the suprachiasmatic nucleus (SCN), which is entrained to the light-dark cycle. Since the circadian CORT rhythm is associated with circadian expression of the steroidogenic acute regulatory (StAR) protein, we investigated the 24h pattern of hormonal secretion (ACTH and CORT), steroidogenic gene expression (StAR, SF-1, DAX1 and Nurr77) and the expression of genes involved in ACTH signalling (MC2R and MRAP) in rats entrained to a normal light-dark cycle. We found that circadian changes in ACTH and CORT were associated with the circadian expression of all gene targets; with SF-1, Nurr77 and MRAP peaking in the evening, and DAX1 and MC2R peaking in the morning. Since disruption of normal SCN activity by exposure to constant light abolishes the circadian rhythm of CORT in the rat, we also investigated whether the AM-PM variation of our target genes was also disrupted in rats exposed to constant light conditions for 5weeks. We found that the disruption of the AM-PM variation of ACTH and CORT secretion in rats exposed to constant light was accompanied by a loss of AM-PM variation in StAR, SF-1 and DAX1, and a reversed AM-PM variation in Nurr77, MC2R and MRAP. Our data suggest that circadian expression of StAR is regulated by the circadian expression of nuclear receptors and proteins involved in both ACTH signalling and StAR transcription. We propose that ACTH regulates the secretion of CORT via the circadian control of steroidogenic gene pathways that become dysregulated under the influence of constant light. PMID:23178164

Park, Shin Y; Walker, Jamie J; Johnson, Nicholas W; Zhao, Zidong; Lightman, Stafford L; Spiga, Francesca

2013-05-22

211

Development of circadian rhythms: role of postnatal light environment.  

PubMed

Mammals are born with an immature circadian system, which completes its development postnatally. Evidence suggests that the environment experienced by a newborn will impact and shape its development, which will have future consequences at the levels of circadian system function, circadian behaviour and physiology, and potentially, the animal's long-term health and welfare. Here we review the various stages in postnatal development of the circadian system, and discuss the data available on the long-term effects of early environment, in particular light environment, on the animal's brain, physiology and behaviour. PMID:23454636

Brooks, Elisabeth; Canal, Maria M

2013-05-01

212

Comparison of synchronization of primate circadian rhythms by light and food  

NASA Technical Reports Server (NTRS)

It is a well-documented fact that cycles of light and dark (LD) are the major entraining agent or 'zeitgeber' for circadian rhythms and that cycles of eating and fasting (EF) are capable of synchronizing a few circadian rhythms in the squirrel monkey. In this paper, by contrasting how these rhythms are timed by LD and EF cycles, the differential coupling to the oscillating system within adult male squirrel monkeys is examined. The variables measured are the rhythms of drinking, colonic temperature, and urinary potassium and water excretion. Attention is given to a comparison of the reproducibility of the averaged waveforms of the rhythms, the stability of the timing of a phase reference point, and the rate of resynchronization of these rhythms following an abrupt 8-hr phase delay in the zeitgeber. It is shown that the colonic temperature rhythm is more tightly controlled by LD than EF cycles, and that the drinking and urinary rhythms are more tightly coupled to EF than LD cycles.

Sulzman, F. M.; Fuller, C. A.; Moore-Ede, M. C.

1978-01-01

213

Modulation of metabolic and clock gene mRNA rhythms by pineal and retinal circadian oscillators.  

PubMed

Avian circadian organization involves interactions between three neural pacemakers: the suprachiasmatic nuclei (SCN), pineal, and retina. Each of these structures is linked within a neuroendocrine loop to influence downstream processes and peripheral oscillations. However, the contribution of each structure to drive or synchronize peripheral oscillators or circadian outputs in avian species is largely unknown. To explore these interactions in the chick, we measured 2-deoxy[(14)C]-glucose (2DG) uptake and mRNA expression of the chick clock genes bmal1, cry1, and per3 in three brain areas and in two peripheral organs in chicks that underwent pinealectomy, enucleation, or sham surgery. We found that 2DG uptake rhythms damp under constant darkness in intact animals, while clock gene mRNA levels continue to cycle, demonstrating that metabolic rhythms are not directly driven by clock gene transcription. Moreover, 2DG rhythms are not phase-locked to rhythms of clock gene mRNA. However, pinealectomy and enucleation had similar disruptive effects on both metabolic and clock gene rhythms, suggesting that both of these oscillators act similarly to reinforce molecular and physiological rhythms in the chicken. Finally, we show that the relative phasing of at least one clock gene, cry1, varies between central and peripheral oscillators in a tissue specific manner. These data point to a complex, differential orchestration of central and peripheral oscillators in the chick, and, importantly, indicate a disconnect between canonical clock gene regulation and circadian control of metabolism. PMID:19136000

Karaganis, Stephen P; Bartell, Paul A; Shende, Vikram R; Moore, Ashli F; Cassone, Vincent M

2009-04-01

214

Modulation of metabolic and clock gene mRNA rhythms by pineal and retinal circadian oscillators  

PubMed Central

Avian circadian organization involves interactions between three neural pacemakers: the suprachiasmatic nuclei (SCN), pineal, and retina. Each of these structures is linked within a neuroendocrine loop to influence downstream processes and peripheral oscillations. However, the contribution of each structure to drive or synchronize peripheral oscillators or circadian outputs in avian species is largely unknown. To explore these interactions in the chick, we measured 2-deoxy[14C]-glucose (2DG) uptake and mRNA expression of the chick clock genes bmal1, cry1, and per3 in three brain areas and in two peripheral organs in chicks that underwent pinealectomy, enucleation, or sham surgery. We found that 2DG uptake rhythms damp under constant darkness in intact animals, while clock gene mRNA levels continue to cycle, demonstrating that metabolic rhythms are not directly driven by clock gene transcription. Moreover, 2DG rhythms are not phase-locked to rhythms of clock gene mRNA. However, pinealectomy and enucleation had similar disruptive effects on both metabolic and clock gene rhythms, suggesting that both of these oscillators act similarly to reinforce molecular and physiological rhythms in the chicken. Finally, we show that the relative phasing of at least one clock gene, cry1, varies between central and peripheral oscillators in a tissue specific manner. These data point to a complex, differential orchestration of central and peripheral oscillators in the chick, and, importantly, indicate a disconnect between canonical clock gene regulation and circadian control of metabolism.

Karaganis, Stephen P.; Bartell, Paul A.; Shende, Vikram R.; Moore, Ashli F.; Cassone, Vincent M.

2009-01-01

215

Standards of evidence in chronobiology: critical review of a report that restoration of Bmal1 expression in the dorsomedial hypothalamus is sufficient to restore circadian food anticipatory rhythms in Bmal1-/- mice  

PubMed Central

Daily feeding schedules generate food anticipatory rhythms of behavior and physiology that exhibit canonical properties of circadian clock control. The molecular mechanisms and location of food-entrainable circadian oscillators hypothesized to control food anticipatory rhythms are unknown. In 2008, Fuller et al reported that food-entrainable circadian rhythms are absent in mice bearing a null mutation of the circadian clock gene Bmal1 and that these rhythms can be rescued by virally-mediated restoration of Bmal1 expression in the dorsomedial nucleus of the hypothalamus (DMH) but not in the suprachiasmatic nucleus (site of the master light-entrainable circadian pacemaker). These results, taken together with controversial DMH lesion results published by the same laboratory, appear to establish the DMH as the site of a Bmal1-dependent circadian mechanism necessary and sufficient for food anticipatory rhythms. However, careful examination of the manuscript reveals numerous weaknesses in the evidence as presented. These problems are grouped as follows and elaborated in detail: 1. data management issues (apparent misalignments of plotted data), 2. failure of evidence to support the major conclusions, and 3. missing data and methodological details. The Fuller et al results are therefore considered inconclusive, and fail to clarify the role of either the DMH or Bmal1 in the expression of food-entrainable circadian rhythms in rodents.

Mistlberger, Ralph E; Buijs, Ruud M; Challet, Etienne; Escobar, Carolina; Landry, Glenn J; Kalsbeek, Andries; Pevet, Paul; Shibata, Shigenobu

2009-01-01

216

Glucocorticoids Play a Key Role in Circadian Cell Cycle Rhythms  

Microsoft Academic Search

Clock output pathways play a pivotal role by relaying timing information from the circadian clock to a diversity of physiological systems. Both cell-autonomous and systemic mechanisms have been implicated as clock outputs; however, the relative importance and interplay between these mechanisms are poorly understood. The cell cycle represents a highly conserved regulatory target of the circadian timing system. Previously, we

Thomas Dickmeis; Kajori Lahiri; Gabriela Nica; Daniela Vallone; Cristina Santoriello; Carl J Neumann; Matthias Hammerschmidt; Nicholas S Foulkes

2007-01-01

217

Circadian rhythms and endocrine functions in adult insects.  

PubMed

Many behavioral and physiological processes in adult insects are influenced by both the endocrine and circadian systems, suggesting that these two key physiological systems interact. We reviewed the literature and found that experiments explicitly testing these interactions in adult insects have only been conducted for a few species. There is a shortage of measurements of hormone titers throughout the day under constant conditions even for the juvenile hormones (JHs) and ecdysteroids, the best studied insect hormones. Nevertheless, the available measurements of hormone titers coupled with indirect evidence for circadian modulation of hormone biosynthesis rate, and the expression of genes encoding proteins involved in hormone biosynthesis, binding or degradation are consistent with the hypothesis that the circulating levels of many insect hormones are influenced by the circadian system. Whole genome microarray studies suggest that the modulation of farnesol oxidase levels is important for the circadian regulation of JH biosynthesis in honey bees, mosquitoes, and fruit flies. Several studies have begun to address the functional significance of circadian oscillations in endocrine signaling. The best understood system is the circadian regulation of Pheromone Biosynthesis Activating Neuropeptide (PBAN) titers which is important for the temporal organization of sexual behavior in female moths. The evidence that the circadian and endocrine systems interact has important implications for studies of insect physiology and behavior. Additional studies on diverse species and physiological processes are needed for identifying basic principles underlying the interactions between the circadian and endocrine systems in insects. PMID:23103982

Bloch, Guy; Hazan, Esther; Rafaeli, Ada

2013-01-01

218

A circadian rhythm in the level of carbon dioxide compensation in Bryophyllum fedtschenkoi with zero values during the transient  

Microsoft Academic Search

Detached shoots of Bryophyllum fedtschenkoi maintained in a closed system in the light exhibited an endogenous circadian rhythm in CO2 compensation. The rhythm was sensitive to changes in light intensity and temperature. At 15° C it damped rapidly in light of 78 J m-2 s-1, but at 10° C a rhythm of considerable amplitude was evident at this same light

M. B. Jones; T. A. Mansfield

1972-01-01

219

Circadian Rhythm of Nitrogenase Gene Expression in the Diazotrophic Filamentous Nonheterocystous Cyanobacterium Trichodesmium sp. Strain IMS 101  

Microsoft Academic Search

Recent studies suggested that the daily cycle of nitrogen fixation activity in the marine filamentous nonhet- erocystous cyanobacterium Trichodesmium sp. is controlled by a circadian rhythm. In this study, we evaluated the rhythm of nitrogen fixation in Trichodesmium sp. strain IMS 101 by using the three criteria for an endogenous rhythm. Nitrogenase transcript abundance oscillated with a period of approximately

YI-BU CHEN; BENNY DOMINIC; MARK T. MELLON; JONATHAN P. ZEHR

1998-01-01

220

A Mutant Drosophila Homolog of Mammalian Clock Disrupts Circadian Rhythms and Transcription of period and timeless  

Microsoft Academic Search

We report the identification, characterization, and cloning of a novel Drosophila circadian rhythm gene, dClock. The mutant, initially called Jrk, manifests dominant effects: heterozygous flies have a period alteration and half are arrhythmic, while homozygous flies are uniformly arrhythmic. Furthermore, these flies express low levels of the two clock proteins, PERIOD (PER) and TIMELESS (TIM), due to low per and

Ravi Allada; Neal E White; W. Venus So; Jeffrey C Hall; Michael Rosbash

1998-01-01

221

Urinary Cortisol Circadian Rhythm in a Group of High-Functioning Children with Autism.  

ERIC Educational Resources Information Center

This study found no evidence for abnormal temporal placement of the basal urinary cortisol circadian rhythm in a group of 18 high-functioning children (ages 4-14) with autism. There was a tendency toward cortisol hypersecretion during the day, predominantly in autistic children who were integrated into the normal school system. (Author/JDD)

Richdale, Amanda L.; Prior, Margot R.

1992-01-01

222

Ontogeny, Circadian Rhythm Pattern, and Hormonal Modulation of 5?-Dihydrotestosterone Receptors in the Rat Pineal  

Microsoft Academic Search

Some physiological parameters of pineal 5?-dihydrotestosterone receptor in the rat such as ontogeny, circadian rhythm pattern, and its modulation by various neuropeptides and neurotransmitters which have profound influences on the pineal hormone melatonin were examined. Pineal 5?-dihydrotestosterone receptors measured at different ages of the animal revealed that on day 10 both cytosolic receptor (CR) and nuclear receptor (NR) levels were

Derek Gupta; Chandana Haldar; Markus Coeleveld; Johannes Roth

1993-01-01

223

Temperature Entrainment of the Circadian Cuticle Deposition Rhythm in Drosophila melanogaster  

Microsoft Academic Search

The cuticle deposition rhythm, which is observed in the apodeme of the furca in the thorax, is controlled by a peripheral circadian clock in the epidermal cells and entrained to light-dark (LD) cycles via CRYPTOCHROME (CRY) in Drosophila melanogaster. In the present study, we examined the effects of temperature (TC) cycles and the combination of LD and TC cycles on

Chihiro Ito; Shin G. Goto; Kenji Tomioka; Hideharu Numata

2011-01-01

224

Relationships between circadian rhythms and modulation of gene expression by glucocorticoids in skeletal muscle  

PubMed Central

The existence and maintenance of biological rhythms linked to the 24-h light-dark cycle are essential to the health and functioning of an organism. Although much is known concerning central clock mechanisms, much less is known about control in peripheral tissues. In this study, circadian regulation of gene expression was examined in rat skeletal muscle. A rich time series involving 54 animals euthanized at 18 distinct time points within the 24-h cycle was performed, and mRNA expression in gastrocnemius muscles was examined using Affymetrix gene arrays. Data mining identified 109 genes that were expressed rhythmically, which could be grouped into eight distinct temporal clusters within the 24-h cycle. These genes were placed into 11 functional categories, which were examined within the context of temporal expression. Transcription factors involved in the regulation of central rhythms were examined, and eight were found to be rhythmically expressed in muscle. Because endogenous glucocorticoids are a major effector of circadian rhythms, genes identified here were compared with those identified in previous studies as glucocorticoid regulated. Of the 109 genes identified here as circadian rhythm regulated, only 55 were also glucocorticoid regulated. Examination of transcription factors involved in circadian control suggests that corticosterone may be the initiator of their rhythmic expression patterns in skeletal muscle.

Almon, Richard R.; Yang, Eric; Lai, William; Androulakis, Ioannis P.; Ghimbovschi, Svetlana; Hoffman, Eric P.; Jusko, William J.; DuBois, Debra C.

2008-01-01

225

Darwin, Earthworms & Circadian Rhythms: A Fertile Field for Science Fair Experiments  

ERIC Educational Resources Information Center

This article discusses why the study of earthworms has fascinated many scientists, and why earthworms make ideal experimental animals for students to test in the laboratory. Although earthworms may appear to be primitive, they are governed by both circadian and seasonal rhythms, just as more advanced organisms are. They possess an intelligence…

Burns, John T.; Scurti, Paul J.; Furda, Amy M.

2009-01-01

226

Impaired circadian rhythm of gastric myoelectrical activity in patients with multiple system atrophy.  

PubMed

In order to evaluate gastric motility and its circadian rhythm in patients with multiple system atrophy (MSA) and healthy control subjects, we measured gastric myoelectrical activity (GMA) for 24 hours using a cutaneous electrogastrogram (EGG) recorder in 14 MSA patients and 9 age-matched controls. We analyzed six 10-minute segments of EGG before and after each meal and two 20-minute EGG segments during sleep; three parameters were used for the analysis: dominant frequency (DF), instability coefficient of dominant frequency (ICDF), and dominant power (DP). DF increased during daytime and decreased during sleep in the control, while this circadian variation was blunted in the patients with MSA. The average DF of the eight segments in the MSA patients did not differ from that of the control. Both MSA patients and control subjects did not show the circadian variation of ICDF and DP. The average ICDF of the eight segments in the patients with MSA was significantly decreased when compared with that of the control (p < 0.01). No differences were observed in DP between the two groups. This study indicates that the healthy subjects appear to have a circadian rhythm of DF, and the patients with MSA appear to have impaired circadian rhythm of DF and decreased ICDF possibly due to the degeneration of the central autonomic neurons. PMID:16362538

Suzuki, Atsuya; Asahina, M; Ishikawa, C; Asahina, K M; Honma, K; Fukutake, T; Hattori, T

2005-12-01

227

Circadian rhythms of melatonin, thy raid?stimulating hormone and body temperature: Relationships among those rhythms and effect of sleep?wake cycle  

Microsoft Academic Search

Plasma melatonin, thyroid?stimulating hormone (TSH) and body temperature were measured simultaneously and continuously before and after the sleep?wake cycle was shifted in 4 healthy males and changes in the circadian rhythm itself and in the phase relationship among these circadian rhythms were determined. Normal sleep?wake cycle (sleep hours: 2300–0700) was delayed by 10 h (sleep hours: 0900–1700) during the experiment.

Hyun J. Lee

2002-01-01

228

Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders  

PubMed Central

The expanding science of circadian rhythm biology and a growing literature in human clinical research on circadian rhythm sleep disorders (CRSDs) prompted the American Academy of Sleep Medicine (AASM) to convene a task force of experts to write a review of this important topic. Due to the extensive nature of the disorders covered, the review was written in two sections. The first review paper, in addition to providing a general introduction to circadian biology, addresses “exogenous” circadian rhythm sleep disorders, including shift work disorder (SWD) and jet lag disorder (JLD). The second review paper addresses the “endogenous” circadian rhythm sleep disorders, including advanced sleep phase disorder (ASPD), delayed sleep phase disorder (DSPD), irregular sleep-wake rhythm (ISWR), and the non–24-hour sleep-wake syndrome (nonentrained type) or free-running disorder (FRD). These practice parameters were developed by the Standards of Practice Committee and reviewed and approved by the Board of Directors of the AASM to present recommendations for the assessment and treatment of CRSDs based on the two accompanying comprehensive reviews. The main diagnostic tools considered include sleep logs, actigraphy, the Morningness-Eveningness Questionnaire (MEQ), circadian phase markers, and polysomnography. Use of a sleep log or diary is indicated in the assessment of patients with a suspected circadian rhythm sleep disorder (Guideline). Actigraphy is indicated to assist in evaluation of patients suspected of circadian rhythm disorders (strength of recommendation varies from “Option” to “Guideline,” depending on the suspected CRSD). Polysomnography is not routinely indicated for the diagnosis of CRSDs, but may be indicated to rule out another primary sleep disorder (Standard). There is insufficient evidence to justify the use of MEQ for the routine clinical evaluation of CRSDs (Option). Circadian phase markers are useful to determine circadian phase and confirm the diagnosis of FRD in sighted and unsighted patients but there is insufficient evidence to recommend their routine use in the diagnosis of SWD, JLD, ASPD, DSPD, or ISWR (Option). Additionally, actigraphy is useful as an outcome measure in evaluating the response to treatment for CRSDs (Guideline). A range of therapeutic interventions were considered including planned sleep schedules, timed light exposure, timed melatonin doses, hypnotics, stimulants, and alerting agents. Planned or prescribed sleep schedules are indicated in SWD (Standard) and in JLD, DSPD, ASPD, ISWR (excluding elderly-demented/nursing home residents), and FRD (Option). Specifically dosed and timed light exposure is indicated for each of the circadian disorders with variable success (Option). Timed melatonin administration is indicated for JLD (Standard); SWD, DSPD, and FRD in unsighted persons (Guideline); and for ASPD, FRD in sighted individuals, and for ISWR in children with moderate to severe psychomotor retardation (Option). Hypnotic medications may be indicated to promote or improve daytime sleep among night shift workers (Guideline) and to treat jet lag-induced insomnia (Option). Stimulants may be indicated to improve alertness in JLD and SWD (Option) but may have risks that must be weighed prior to use. Modafinil may be indicated to improve alertness during the night shift for patients with SWD (Guideline). Citation: Morgenthaler TI; Lee-Chiong T; Alessi C; Friedman L; Aurora N; Boehlecke B; Brown T; Chesson AL; Kapur V; Maganti R; Owens J; Pancer J; Swick TJ; Zak R; Standards of Practice Committee of the AASM. Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders. SLEEP 2007;30(11):1445-1459.

Morgenthaler, Timothy I.; Lee-Chiong, Teofilo; Alessi, Cathy; Friedman, Leah; Aurora, R. Nisha; Boehlecke, Brian; Brown, Terry; Chesson, Andrew L.; Kapur, Vishesh; Maganti, Rama; Owens, Judith; Pancer, Jeffrey; Swick, Todd J.; Zak, Rochelle

2007-01-01

229

Circadian Rhythm of Redox State Regulates Excitability in Suprachiasmatic Nucleus Neurons  

PubMed Central

Daily rhythms of mammalian physiology, metabolism, and behavior parallel the day-night cycle. They are orchestrated by a central circadian clock in the brain, the suprachiasmatic nucleus (SCN). Transcription of clock genes is sensitive to metabolic changes in reduction and oxidation (redox); however, circadian cycles in protein oxidation have been reported in anucleate cells, where no transcription occurs. We tested whether the SCN also expresses redox cycles and how such metabolic oscillations might affect neuronal physiology. We detected self-sustained circadian rhythms of SCN redox state that required the molecular clockwork. The redox oscillation could determine the excitability of SCN neurons through non-transcriptional modulation of multiple K+ channels. Thus, dynamic regulation of SCN excitability appears to be closely tied to metabolism that engages the clockwork machinery.

Wang, Tongfei A.; Yu, Yanxun V.; Govindaiah, Gubbi; Ye, Xiaoying; Artinian, Liana; Coleman, Todd P.; Sweedler, Jonathan V.; Cox, Charles L.; Gillette, Martha U.

2012-01-01

230

Circadian rhythms of the L-ascorbic acid level in Euglena and spinach.  

PubMed

Plant defenses against photo-oxidative stress have been studied almost exclusively with respect to stress responses, and little is known about how non-enzymic antioxidants change under constant conditions without a time cue or an environmental stress. Here, we show that, in both the flagellated alga Euglena gracilis Z and the angiosperm Spinacia oleracea L., the potent antioxidant L-ascorbic acid (Asc) displays a circadian rhythm with a maximum at subjective midday, a physiological state reflecting that attained at noon under daily light/dark cycles. Thus, photosynthetic organisms can maximize antioxidant levels in anticipation of midday, when photo-oxidative stress is most severe. These results may partly explain the in-phase circadian UV-C resistance rhythm recently identified in the alga. However, the Asc, but not the resistance, rhythm wanes in continuous darkness. This suggests the presence of persistent circadian rhythms in the levels of other antioxidants in continuous darkness, which may account for the UV-C resistance rhythm. PMID:16679025

Kiyota, Maki; Numayama, Naoko; Goto, Ken

2006-09-01

231

Drosophila TRPA1 functions in temperature control of circadian rhythm in pacemaker neurons.  

PubMed

Most animals from flies to humans count on circadian clocks to synchronize their physiology and behaviors. Daily light cycles are well known environmental cues for setting circadian rhythms. Warmer and cooler temperatures that mimic day and night are also effective in entraining circadian activity in most animals. Even vertebrate organisms can be induced to show circadian responses through exposure to temperature cycles. In poikilothermic animals such as Drosophila, temperature differences of only 2-3°C are sufficient to synchronize locomotor rhythms. However, the molecular sensors that participate in temperature regulation of circadian activity in fruit flies or other animals are enigmatic. It is also unclear whether such detectors are limited to the periphery or may be in the central brain. Here, we showed that Drosophila TRPA1 (transient receptor potential cation channel A1) was necessary for normal activity patterns during temperature cycles. The trpA1 gene was expressed in a subset of pacemaker neurons in the central brain. In response to temperature entrainment, loss of trpA1 impaired activity, and altered expression of the circadian clock protein period (Per) in a subset of pacemaker neurons. These findings underscore a role for a thermoTRP in temperature regulation that extends beyond avoidance of noxious or suboptimal temperatures. PMID:23595730

Lee, Youngseok; Montell, Craig

2013-04-17

232

Glucocorticoid-mediated Period2 induction delays the phase of circadian rhythm  

PubMed Central

Glucocorticoid (GC) signaling synchronizes the circadian rhythm of individual peripheral cells and induces the expression of circadian genes, including Period1 (Per1) and Period2 (Per2). However, no GC response element (GRE) has been reported in the Per2 promoter region. Here we report the molecular mechanisms of Per2 induction by GC signaling and its relevance to the regulation of circadian timing. We found that GC prominently induced Per2 expression and delayed the circadian phase. The overlapping GRE and E-box (GE2) region in the proximal Per2 promoter was responsible for GC-mediated Per2 induction. The GRE in the Per2 promoter was unique in that brain and muscle ARNT-like protein-1 (BMAL1) was essential for GC-induced Per2 expression, whereas other GRE-containing promoters, such as Per1 and mouse mammary tumor virus, responded to dexamethasone in the absence of BMAL1. This specialized regulatory mechanism was mediated by BMAL1-dependent binding of the GC receptor to GRE in Per2 promoter. When Per2 induction was abrogated by the mutation of the GRE or E-box, the circadian oscillation phase failed to be delayed compared with that of the wild-type. Therefore, the current study demonstrates that the rapid Per2 induction mediated by GC is crucial for delaying the circadian rhythm.

Cheon, Solmi; Park, Noheon; Cho, Sehyung; Kim, Kyungjin

2013-01-01

233

Neurophysiological and Behavioural Analysis of Circadian Rhythm Entrainment.  

National Technical Information Service (NTIS)

We investigated neurotransmitters which play a role in conveying light information to the circadian clock in the suprachiasmatic nucleus (SCN). We studies the effects on SCN cell responses to light of classic small-molecule transmitters, such as glutamate...

B. Rusak

2000-01-01

234

Neurophysiological and Behavioural Analysis of Circadian Rhythm Entrainment.  

National Technical Information Service (NTIS)

We investigated neurotransmitters which play a role in conveying light information to the circadian clock in the suprachiasmatic nucleus (SON). We studied the effects on SON cell responses to light of classic small-molecule transmitters, such as glutamate...

B. Rusak

2000-01-01

235

Modifications of circadian and circannual rhythms with aging  

Microsoft Academic Search

Whereas biological rhythms are now fairly well documented in young healthy adults, reports in elderly are relatively few for obvious reasons, including the difficulty of setting groups matched in age, sociological and professional background, medical history, and not in need of specific medication. Aging may modify one or several parameters characterizing biological rhythms. The modifications are different from one function

Yvan Touitou; André Bogdan; Erhard Haus; Catherine Touitou

1997-01-01

236

Simulation analysis for the effect of light-dark cycle on the entrainment in circadian rhythm.  

PubMed

Circadian rhythms of the living organisms are 24hr oscillations found in behavior, biochemistry and physiology. Under constant conditions, the rhythms continue with their intrinsic period length, which are rarely exact 24hr. In this paper, we examine the effects of light on the phase of the gene expression rhythms derived from the interacting feedback network of a few clock genes, taking advantage of a computer simulation with Cell Illustrator. The simulation results suggested that the interacting circadian feedback network at the molecular level is essential for phase dependence of the light effects, observed in mammalian behavior. Furthermore, the simulation reproduced the biological observations that the range of entrainment to shorter or longer than 24hr light-dark cycles is limited, centering around 24hr. Application of our model to inter-time zone flight successfully demonstrated that 6 to 7 days are required to recover from jet lag when traveling from Tokyo to New York. PMID:19425160

Mitou, Natsumi; Ikegami, Yuto; Matsuno, Hiroshi; Miyano, Satoru; Inouye, Shin-ichi T

2008-01-01

237

Alteration of Daily and Circadian Rhythms following Dopamine Depletion in MPTP Treated Non-Human Primates  

PubMed Central

Disturbances of the daily sleep/wake cycle are common non-motor symptoms of Parkinson's disease (PD). However, the impact of dopamine (DA) depletion on circadian rhythms in PD patients or non-human primate (NHP) models of the disorder have not been investigated. We evaluated alterations of circadian rhythms in NHP following MPTP lesion of the dopaminergic nigro-striatal system. DA degeneration was assessed by in vivo PET ([11C]-PE2I) and post-mortem TH and DAT quantification. In a light?dark cycle, control and MPTP-treated NHP both exhibit rest-wake locomotor rhythms, although DA-depleted NHP show reduced amplitude, decreased stability and increased fragmentation. In all animals, 6-sulphatoxymelatonin peaks at night and cortisol in early morning. When the circadian system is challenged by exposure to constant light, controls retain locomotor rest-wake and hormonal rhythms that free-run with stable phase relationships whereas in the DA-depleted NHP, locomotor rhythms are severely disturbed or completely abolished. The amplitude and phase relations of hormonal rhythms nevertheless remain unaltered. Use of a light-dark masking paradigm shows that expression of daily rest-wake activity in MPTP monkeys requires the stimulatory and inhibitory effects of light and darkness. These results suggest that following DA lesion, the central clock in the SCN remains intact but, in the absence of environmental timing cues, is unable to drive downstream rhythmic processes of striatal clock gene and dopaminergic functions that control locomotor output. These findings suggest that the circadian component of the sleep-wake disturbances in PD is more profoundly affected than previously assumed.

Fifel, Karim; Vezoli, Julien; Dzahini, Kwamivi; Claustrat, Bruno; Leviel, Vincent; Kennedy, Henry; Procyk, Emmanuel; Dkhissi-Benyahya, Ouria; Gronfier, Claude; Cooper, Howard M.

2014-01-01

238

Changes in Intracellular pH Are Not Correlated with the Circadian Rhythm of Neurospora  

PubMed Central

Intracellular pH (pHi) was measured during the circadian cycle of Neurospora. Internal pH of Neurospora cultures in liquid medium was assayed by the 5,5-dimethyl-2,4-oxazolidinedione method and gave values for pHi which were similar to those previously obtained by other workers using pH-microelectrodes with agar-grown cultures. Cytoplasmic pH changed in liquid medium cultures, but these changes were not related to the circadian clock. Furthermore, treatments which raise or lower pHi do not phase-shift the circadian rhythm. These results indicate that pHi plays no specific role in regulating the circadian clock of Neurospora.

Johnson, Carl Hirschie

1983-01-01

239

Assessment of circadian rhythms in humans: comparison of real-time fibroblast reporter imaging with plasma melatonin.  

PubMed

We compared the period of the rhythm of plasma melatonin, driven by the hypothalamic circadian pacemaker, to in vitro periodicity in cultured peripheral fibroblasts to assess the effects on these rhythms of a polymorphism of PER3 (rs57875989), which is associated with sleep timing. In vitro circadian period was determined using luminometry of cultured fibroblasts, in which the expression of firefly luciferase was driven by the promoter of the circadian gene Arntl (Bmal1). The period of the melatonin rhythm was assessed in a 9-d forced desynchrony protocol, minimizing confounding effects of sleep-wake and light-dark cycles on circadian rhythmicity. In vitro periods (32 participants, 24.61±0.33 h, mean±SD) were longer than in vivo periods (31 participants, 24.16±0.17 h; P<0.0001) but did not differ between PER3 genotypes (P>0.4). Analyses of replicate in vitro assessments demonstrated that circadian period was reproducible within individuals (intraclass correlation=0.62), but in vivo and in vitro period assessments did not correlate (P>0.9). In accordance with circadian entrainment theory, in vivo period correlated with the timing of melatonin (P<0.05) at baseline and with diurnal preference (P<0.05). Individual circadian rhythms can be reliably assessed in fibroblasts but may not correlate with physiological rhythms driven by the central circadian pacemaker. PMID:22371527

Hasan, Sibah; Santhi, Nayantara; Lazar, Alpar S; Slak, Ana; Lo, June; von Schantz, Malcolm; Archer, Simon N; Johnston, Jonathan D; Dijk, Derk-Jan

2012-06-01

240

WNK-OSR1/SPAK-NCC signal cascade has circadian rhythm dependent on aldosterone.  

PubMed

Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone. PMID:23044422

Susa, Koichiro; Sohara, Eisei; Isobe, Kiyoshi; Chiga, Motoko; Rai, Tatemitsu; Sasaki, Sei; Uchida, Shinichi

2012-11-01

241

Influence of photoperiod and running wheel access on the entrainment of split circadian rhythms in hamsters  

PubMed Central

Background In the laboratory, behavioral and physiological states of nocturnal rodents alternate, with a period near 24 h, between those appropriate for the night (e.g., elevated wheel-running activity and high melatonin secretion) and for the day (e.g., rest and low melatonin secretion). Under appropriate 24 h light:dark:light:dark conditions, however, rodents may be readily induced to express bimodal rest/activity cycles that reflect a global temporal reorganization of the central neural pacemaker in the hypothalamus. We examine here how the relative length of the light and dark phases of the environmental cycle influences this rhythm splitting and the necessity of a running wheel for expression of this entrainment condition. Results Rhythm splitting was observed in wheel-running and general locomotion of Siberian and Syrian hamsters. The latter also manifest split rhythms in body temperature. Access to a running wheel was necessary neither for the induction nor maintenance of this entrainment pattern. While rhythms were only transiently split in many animals with two 5 h nights, the incidence of splitting was greater with twice daily nights of shorter duration. Removal of running wheels altered the body temperature rhythm but did not eliminate its clear bimodality. Conclusion The expression of entrained, split circadian rhythms exhibits no strict dependence on access to a running wheel, but can be facilitated by manipulation of ambient lighting conditions. These circadian entrainment patterns may be of therapeutic value to human shift-workers and others facing chronobiological challenges.

Rosenthal, Sheila L; Vakili, Martin M; Evans, Jennifer A; Elliott, Jeffrey A; Gorman, Michael R

2005-01-01

242

A riot of rhythms: neuronal and glial circadian oscillators in the mediobasal hypothalamus  

PubMed Central

Background In mammals, the synchronized activity of cell autonomous clocks in the suprachiasmatic nuclei (SCN) enables this structure to function as the master circadian clock, coordinating daily rhythms in physiology and behavior. However, the dominance of this clock has been challenged by the observations that metabolic duress can over-ride SCN controlled rhythms, and that clock genes are expressed in many brain areas, including those implicated in the regulation of appetite and feeding. The recent development of mice in which clock gene/protein activity is reported by bioluminescent constructs (luciferase or luc) now enables us to track molecular oscillations in numerous tissues ex vivo. Consequently we determined both clock activities and responsiveness to metabolic perturbations of cells and tissues within the mediobasal hypothalamus (MBH), a site pivotal for optimal internal homeostatic regulation. Results Here we demonstrate endogenous circadian rhythms of PER2::LUC expression in discrete subdivisions of the arcuate (Arc) and dorsomedial nuclei (DMH). Rhythms resolved to single cells did not maintain long-term synchrony with one-another, leading to a damping of oscillations at both cell and tissue levels. Complementary electrophysiology recordings revealed rhythms in neuronal activity in the Arc and DMH. Further, PER2::LUC rhythms were detected in the ependymal layer of the third ventricle and in the median eminence/pars tuberalis (ME/PT). A high-fat diet had no effect on the molecular oscillations in the MBH, whereas food deprivation resulted in an altered phase in the ME/PT. Conclusion Our results provide the first single cell resolution of endogenous circadian rhythms in clock gene expression in any intact tissue outside the SCN, reveal the cellular basis for tissue level damping in extra-SCN oscillators and demonstrate that an oscillator in the ME/PT is responsive to changes in metabolism.

Guilding, Clare; Hughes, Alun TL; Brown, Timothy M; Namvar, Sara; Piggins, Hugh D

2009-01-01

243

Circadian locomotor rhythms in the cricket, Gryllodes sigillatus. I. Localization of the pacemaker and the photoreceptor.  

PubMed

Circadian locomotor rhythm and its underlying mechanism were investigated in the cricket, Gryllodes sigillatus. Adult male crickets showed a nocturnal locomotor rhythm peaking early in the dark phase of a light to dark cycle. This rhythm persisted under constant darkness (DD) with a free-running period averaging 23.1 +/- 0.3 hr. Although constant bright light made most animals arrhythmic, about 40% of the animals showed free-running rhythms with a period longer than 24 hr under constant dim light condition. On transfer to DD, all arrhythmic animals restored the locomotor rhythm. Bilateral optic nerve severance resulted in free-running of the rhythm even under light-dark cycles. The free-running period of the optic nerve severed animals was significantly longer than sham operated crickets in DD, suggesting that the compound eye plays some role in determining the free-running period. Removal of bilateral lamina-medulla portion of the optic lobe abolished the rhythm under DD. These results demonstrate that the photoreceptor for entrainment is the compound eye and the optic lobe is indispensable for persistence of the rhythm. However, 75% and 54% of the optic lobeless animals showed aberrant rhythms with a period very close to 24 hr under light and temperature cycles, respectively, suggesting that there are neural and/or humoral mechanisms for the aberrant rhythms outside of the optic lobe. Since ocelli removal did not affect the photoperiodically induced rhythm, it is likely that the photoreception for the rhythm is performed through an extraretinal photoreceptor. PMID:9450385

Abe, Y; Ushirogawa, H; Tomioka, K

1997-10-01

244

Changes in circadian rhythm of prolactin in short children are dependent on growth hormone secretion.  

PubMed

introduction and objective. Taking into consideration the common ontogenic origin of prolactin (Prl) and growth hormone (GH), the Prl circadian pattern was analysed in children with different degrees of GH deficiency (GHD). materials and methods. The analysis comprised 100 short children (31 girls and 69 boys), aged: 10.1±3.51 years. Based on maximal GH secretion (GHmax) during two stimulating tests multiple hormone deficiency (MPHD), severe isolated GHD (SIGHD), partial isolated GHD (PIGHD) or idiopathic short stature (ISS) were diagnosed. Non-inferential chronobiometry (macroscopic analysis) of the circadian Prl rhythm, based on serum Prl measured every 3 hours during 24 hours, was performed. In this analysis, mesor, the area under curve (AUC), peak and trough level, dispersion, mean nocturnal and diurnal concentration, night/day ratio, amplitude and regression index were estimated. results. In the study group, the positive correlations between GHmax and Prl concentrations at 02:00 and at 05:00 were observed, as well as between GHmax and mesor, amplitude, mean nocturnal concentration, night/day ratio and AUC. The nocturnal rise of Prl secretion was blunted in 100% MPHD and 50% SIGHD children, whereas in most children with PIGHD and ISS, the circadian Prl rhythm was normal. conclusions. 1) In short children, the lower the concentration of GH is, the more blunted nocturnal Prl secretion becomes. 2) In the majority of MPHD and SIGHD children (but not PIGHD), the circadian Prl rhythm was disturbed; namely, reduced nocturnal Prl secretion was noticeable. PMID:24959807

Stawerska, Renata; Smyczy?ska, Joanna; Hilczer, Maciej; Lewi?ski, Andrzej

2014-06-10

245

Identification of a circadian output circuit for rest:activity rhythms in Drosophila.  

PubMed

Though much is known about the cellular and molecular components of the circadian clock, output pathways that couple clock cells to overt behaviors have not been identified. We conducted a screen for circadian-relevant neurons in the Drosophila brain and report here that cells of the pars intercerebralis (PI), a functional homolog of the mammalian hypothalamus, comprise an important component of the circadian output pathway for rest:activity rhythms. GFP reconstitution across synaptic partners (GRASP) analysis demonstrates that PI cells are connected to the clock through a polysynaptic circuit extending from pacemaker cells to PI neurons. Molecular profiling of relevant PI cells identified the corticotropin-releasing factor (CRF) homolog, DH44, as a circadian output molecule that is specifically expressed by PI neurons and is required for normal rest:activity rhythms. Notably, selective activation or ablation of just six DH44+ PI cells causes arrhythmicity. These findings delineate a circuit through which clock cells can modulate locomotor rhythms. PMID:24766812

Cavanaugh, Daniel J; Geratowski, Jill D; Wooltorton, Julian R A; Spaethling, Jennifer M; Hector, Clare E; Zheng, Xiangzhong; Johnson, Erik C; Eberwine, James H; Sehgal, Amita

2014-04-24

246

Circadian rhythms in biologically closed electrical circuits of plants.  

PubMed

The circadian clock regulates a wide range of electrophysiological and developmental processes in plants. Here, we discuss the direct influence of a circadian clock on biologically closed electrochemical circuits in vivo. The biologically closed electrochemical circuits in the leaves of C. miniata (Kaffir lily), Aloe vera and Mimosa pudica, which regulate their physiology, were analyzed using the charge stimulation method. Plants are able to memorize daytime and nighttime. Even at continuous light or darkness, plants recognize nighttime or daytime and change the input resistance. The circadian clock can be maintained endogenously and has electrochemical oscillators, which can activate ion channels in biologically closed electrochemical circuits. The activation of voltage gated channels depends on the applied voltage, electrical charge, and the speed of transmission of electrical energy from the electrostimulator to plants. PMID:22353874

Volkov, Alexander; Waite, Astian J; Wooten, Joseph D; Markin, Vladislav S

2012-02-01

247

Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights  

NASA Technical Reports Server (NTRS)

Sleep, circadian rhythm, and neurobehavioral performance measures were obtained in five astronauts before, during, and after 16-day or 10-day space missions. In space, scheduled rest-activity cycles were 20-35 min shorter than 24 h. Light-dark cycles were highly variable on the flight deck, and daytime illuminances in other compartments of the spacecraft were very low (5.0-79.4 lx). In space, the amplitude of the body temperature rhythm was reduced and the circadian rhythm of urinary cortisol appeared misaligned relative to the imposed non-24-h sleep-wake schedule. Neurobehavioral performance decrements were observed. Sleep duration, assessed by questionnaires and actigraphy, was only approximately 6.5 h/day. Subjective sleep quality diminished. Polysomnography revealed more wakefulness and less slow-wave sleep during the final third of sleep episodes. Administration of melatonin (0.3 mg) on alternate nights did not improve sleep. After return to earth, rapid eye movement (REM) sleep was markedly increased. Crewmembers on these flights experienced circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and postflight changes in REM sleep.

Dijk, D. J.; Neri, D. F.; Wyatt, J. K.; Ronda, J. M.; Riel, E.; Ritz-De Cecco, A.; Hughes, R. J.; Elliott, A. R.; Prisk, G. K.; West, J. B.; Czeisler, C. A.

2001-01-01

248

Cortisol and epinephrine control opposing circadian rhythms in T cell subsets  

PubMed Central

Pronounced circadian rhythms in numbers of circulating T cells reflect a systemic control of adaptive immunity whose mechanisms are obscure. Here, we show that circadian variations in T cell subpopulations in human blood are differentially regulated via release of cortisol and catecholamines. Within the CD4+ and CD8+ T cell subsets, naive cells show pronounced circadian rhythms with a daytime nadir, whereas (terminally differentiated) effector CD8+ T cell counts peak during daytime. Naive T cells were negatively correlated with cortisol rhythms, decreased after low-dose cortisol infusion, and showed highest expression of CXCR4, which was up-regulated by cortisol. Effector CD8+ T cells were positively correlated with epinephrine rhythms, increased after low-dose epinephrine infusion, and showed highest expression of ?-adrenergic and fractalkine receptors (CX3CR1). Daytime increases in cortisol via CXCR4 probably act to redistribute naive T cells to bone marrow, whereas daytime increases in catecholamines via ?-adrenoceptors and, possibly, a suppression of fractalkine signaling promote mobilization of effector CD8+ T cells from the marginal pool. Thus, activation of the major stress hormones during daytime favor immediate effector defense but diminish capabilities for initiating adaptive immune responses.

Dimitrov, Stoyan; Benedict, Christian; Heutling, Dennis; Westermann, Jurgen; Born, Jan

2009-01-01

249

Circadian and circannual rhythms of cortisol, ACTH, and ?-melanocyte-stimulating hormone in healthy horses.  

PubMed

Cosinor analysis was used to evaluate whether pituitary and adrenal hormones exhibit circadian rhythmicity in horses. The effect of season and animal age on their respective rhythms was also determined. In addition, the usefulness of evaluating cortisol rhythmicity for the diagnosis of pituitary pars intermedia dysfunction (PPID) was assessed. Serum cortisol concentrations (P < 0.01), but not plasma ACTH or ?-melanocyte-stimulating hormone (?-MSH), showed a significant circadian periodicity in horses. An effect of season on hormone concentration was observed with plasma ACTH and ?-MSH concentration greater in the fall and cortisol concentration greater in the spring (P < 0.001). Age did not affect cortisol rhythm, but it did blunt the variation in cortisol concentration in horses, similar to what has been previously reported to occur in aged people and dogs. In addition, our results suggest that clinically and diagnostically normal, non-PPID-affected horses commonly have a loss of cortisol diurnal rhythm. Therefore, measurement of circadian rhythm is not an appropriate diagnostic test for PPID. PMID:22717182

Cordero, M; Brorsen, B W; McFarlane, D

2012-11-01

250

Mechanisms of rapid antidepressant effects of sleep deprivation therapy: clock genes and circadian rhythms.  

PubMed

A significant subset of both major depressive disorder and bipolar disorder patients rapidly (within 24 hours) and robustly improves with the chronotherapeutic intervention of sleep deprivation therapy (SDT). Major mood disorder patients are reported to have abnormal circadian rhythms including temperature, hormonal secretion, mood, and particularly sleep. These rhythms are modulated by the clock gene machinery and its products. It is hypothesized that SDT resets abnormal clock gene machinery, that relapse of depressive symptoms during recovery night sleep reactivates abnormal clock gene machinery, and that supplemental chronotherapies and medications can block relapse and help stabilize circadian-related improvement. The central circadian clock genes, BMAL1/CLOCK (NPAS2), bind to Enhancer Boxes to initiate the transcription of circadian genes, including the period genes (per1, per2, per3). It is suggested that a defect in BMAL1/CLOCK (NPAS2) or in the Enhancer Box binding contributes to altered circadian function associated, in part, with the period genes. The fact that chronotherapies, including SDT and sleep phase advance, are dramatically effective suggests that altered clock gene machinery may represent a core pathophysiological defect in a subset of mood disorder patients. PMID:22906517

Bunney, Blynn G; Bunney, William E

2013-06-15

251

Pharmacological modulation of circadian rhythms by synthetic activators of the deacetylase SIRT1  

PubMed Central

Circadian rhythms govern a wide variety of physiological and metabolic functions in many organisms, from prokaryotes to humans. We previously reported that silent information regulator 1 (SIRT1), a NAD+-dependent deacetylase, contributes to circadian control. In addition, SIRT1 activity is regulated in a cyclic manner in virtue of the circadian oscillation of the coenzyme NAD+. Here we used specific SIRT1 activator compounds both in vitro and in vivo. We tested a variety of compounds to show that the activation of SIRT1 alters CLOCK:BMAL1-driven transcription in different systems. Activation of SIRT1 induces repression of circadian gene expression and decreases H3 K9/K14 acetylation at corresponding promoters in a time-specific manner. Specific activation of SIRT1 was demonstrated in vivo using liver-specific SIRT1-deficient mice, where the effect of SIRT1 activator compounds was shown to be dependent on SIRT1. Our findings demonstrate that SIRT1 can fine-tune circadian rhythm and pave the way to the development of pharmacological strategies to address a broad range of therapeutic indications.

Bellet, Marina M.; Nakahata, Yasukazu; Boudjelal, Mohamed; Watts, Emma; Mossakowska, Danuta E.; Edwards, Kenneth A.; Cervantes, Marlene; Astarita, Giuseppe; Loh, Christine; Ellis, James L.; Vlasuk, George P.; Sassone-Corsi, Paolo

2013-01-01

252

Exploring the transcriptional landscape of plant circadian rhythms using genome tiling arrays  

PubMed Central

Background Organisms are able to anticipate changes in the daily environment with an internal oscillator know as the circadian clock. Transcription is an important mechanism in maintaining these oscillations. Here we explore, using whole genome tiling arrays, the extent of rhythmic expression patterns genome-wide, with an unbiased analysis of coding and noncoding regions of the Arabidopsis genome. Results As in previous studies, we detected a circadian rhythm for approximately 25% of the protein coding genes in the genome. With an unbiased interrogation of the genome, extensive rhythmic introns were detected predominantly in phase with adjacent rhythmic exons, creating a transcript that, if translated, would be expected to produce a truncated protein. In some cases, such as the MYB transcription factor AT2G20400, an intron was found to exhibit a circadian rhythm while the remainder of the transcript was otherwise arrhythmic. In addition to several known noncoding transcripts, including microRNA, trans-acting short interfering RNA, and small nucleolar RNA, greater than one thousand intergenic regions were detected as circadian clock regulated, many of which have no predicted function, either coding or noncoding. Nearly 7% of the protein coding genes produced rhythmic antisense transcripts, often for genes whose sense strand was not similarly rhythmic. Conclusions This study revealed widespread circadian clock regulation of the Arabidopsis genome extending well beyond the protein coding transcripts measured to date. This suggests a greater level of structural and temporal dynamics than previously known.

Hazen, Samuel P; Naef, Felix; Quisel, Tom; Gendron, Joshua M; Chen, Huaming; Ecker, Joseph R; Borevitz, Justin O; Kay, Steve A

2009-01-01

253

GABA and $G_{io}$ Differentially Control Circadian Rhythms and Synchrony in Clock Neurons  

Microsoft Academic Search

Neurons in the mammalian suprachiasmatic nuclei (SCN) generate daily rhythms in physiology and behavior, but it is unclear how they maintain and synchronize these rhythms in vivo. We hypothesized that parallel signaling pathways in the SCN are required to synchronize rhythms in these neurons for coherent output. We recorded firing and clock-gene expression patterns while blocking candidate signaling pathways for

Sara J. Aton; James E. Huettner; Martin Straume; Erik D. Herzog

2006-01-01

254

Depressive Symptoms and Circadian Activity Rhythm Disturbances in Community-Dwelling Older Women  

PubMed Central

Objectives Aging is associated with changes in circadian rhythms. Current evidence supports a role for circadian rhythms in the pathophysiology of depression. However, little is known about the relationship between depressive symptoms and circadian activity rhythms in older adults. We examined this association in community-dwelling older women. Methods We performed a cross-sectional analysis of 3,020 women (mean age: 83.55 ± 3.79 years) enrolled in the Study of Osteoporotic Fractures. Depressive symptoms were assessed with the Geriatric Depression Scale categorizing participants as “normal” (0–2; referent group, N = 1,961), “some depressive symptoms” (3–5, N = 704), or “depressed” (?6, N = 355). Circadian activity rhythm variables were measured using wrist actigraphy. Results In age-adjusted and Study of Osteoporotic Fractures site–adjusted models, greater levels of depressive symptoms were associated with decreased amplitude (height; df = 3,014, t = ?11.31, p for linear trend <0.001), pseudo F-statistic (robustness; df =3,014, t =?8.07, p for linear trend <0.001), and mesor (mean modeled activity; df = 3014, t = ?10.36, p for linear trend <0.001) of circadian activity rhythms. Greater levels of depressive symptoms were also associated with increased odds of being in the lowest quartile for amplitude (df =1, ?2 =9240, p for linear trend <0.001), pseudo F-statistic (df =1, ?2 =49.73, p for linear trend <0.001), and mesor (df =1, ?2 =81.12, p for linear trend <0.001). These associations remained significant in multivariate models. Post-hoc analyses comparing mean amplitude, mesor, and pseudo F-statistic values pair-wise between depression-level groups revealed significant differences between women with “some depressive symptoms” and the “normal” group. Conclusion These data suggest a graded association between greater levels of depressive symptoms and more desynchronization of circadian activity rhythms in community-dwelling older women. This association was observed even for women endorsing subthreshold levels of depressive symptoms.

Maglione, Jeanne E.; Ancoli-Israel, Sonia; Peters, Katherine W.; Paudel, Misti L.; Yaffe, Kristine; Ensrud, Kristine E.; Tranah, Greg J.; Stone, Katie L.

2014-01-01

255

Involvement of the Circadian Rhythm and Inflammatory Cytokines in the Pathogenesis of Rheumatoid Arthritis  

PubMed Central

Among the symptoms of patients with rheumatoid arthritis (RA), joint stiffness is influenced by diurnal rhythm and reaches peak in the morning, which is a common complaint and reflects the circadian nature of disease manifestation. In addition, inflammatory cytokines, which reach peak secretion early in the morning are major players causing the morning stiffness. In this review, we explore the link between the circadian clock and inflammation, focusing on the interactions of various clock genes with the immune-pathways underlying the pathology of rheumatoid arthritis.

Yoshida, Kohsuke; Hashimoto, Teppei; Sakai, Yoshitada; Hashiramoto, Akira

2014-01-01

256

Mind your rhythms: an important role for circadian genes in neuroprotection  

PubMed Central

Circadian rhythms govern nearly every physiological process in our brains and bodies. At the most basic level, the molecular clockwork in each cell interacts with metabolic cycles to influence the redox state, allowing for increased cellular activity at specific times of day. In this issue of the JCI, Musiek et al. show that genetic disruptions in the positive arm of the molecular clock can lead to severe astrogliosis, which likely occurs through disruptions in output genes that keep oxidative stress in check. This study demonstrates the importance of proper circadian protein function in the maintenance of neuronal integrity.

McClung, Colleen A.

2013-01-01

257

Circadian rhythms in electrical circuits of Clivia miniata  

Microsoft Academic Search

The biological clock regulates a wide range of physiological processes in plants. Here we show circadian variation of the Clivia miniata responses to electrical stimulation. The biologically closed electrochemical circuits in the leaves of C. miniata (Kaffir lily), which regulate its physiology, were analyzed in vivo using the charge stimulation method. The electrostimulation was provided with different voltages and electrical

Alexander G. Volkov; Joseph D. Wooten; Astian J. Waite; Corydon R. Brown; Vladislav S. Markin

2011-01-01

258

Circadian rhythms in Limulus photoreceptors. II. Quantum bumps  

Microsoft Academic Search

The light response of the lateral eye of the horseshoe crab, Limulus polyphemus, increases at night, while the frequency of spontaneous discrete fluctu- ations of its photoreceptor membrane potential (quantum bumps) decreases. These changes are controlled by a circadian clock in the brain, which transmits activity to the eye via efferent optic nerve fibers (Barlow, R. B., S. J. Bolanski,

E. Kaplan; R. B. BARLOW; G. RENNINGER; K. PURPURA

1990-01-01

259

The alteration of human sleep and circadian rhythms during spaceflight.  

PubMed

Numerous anecdotes in the past suggest the concept that sleep disturbances in astronauts occur more frequently during spaceflight than on ground. Such disturbances may be caused in part by exogenous factors, but also an altered physiological state under microgravity may add to reducing sleep quality in a spacecraft. The present investigation aims at a better understanding of possible sleep disturbances under microgravity. For the first time, experiments were conducted in which sleep and circadian regulation could be simultaneously assessed in space. Four astronauts took part in this study aboard the Russian MIR station. Sleep was recorded polygraphically on tape together with body temperature. For a comparison, the same parameters were measured during baseline periods preceding the flights. The circadian phase of body temperature was found to be delayed by about 2 h in space compared with baseline data. A free-run was not observed during the first 30 d in space. Sleep was shorter and more disturbed than on earth. In addition, the structure of sleep was significantly altered. In space, the latency to the first REM episode was shorter, and slow-wave sleep was redistributed from the first to the second sleep cycle. Several mechanisms may be responsible for these alterations in sleep regulation and circadian phase. Most likely, altered circadian zeitgebers on MIR and a deficiency in the process S of Borbély's sleep model cause the observed findings. The change in process S may be related to changes in physical activity as a result of weightlessness. PMID:9125693

Gundel, A; Polyakov, V V; Zulley, J

1997-03-01

260

Circadian Rhythms of Isoprene Biosynthesis in Grey Poplar Leaves1  

PubMed Central

Isoprene (2-methyl-1,3-butadiene) emission varies diurnally in different species. In poplar (Populus spp.), it has recently been shown that the gene encoding the synthesizing enzyme for isoprene, isoprene synthase (ISPS), displays diurnal variation in expression. Working on shoot cultures of Grey poplar (Populus × canescens) placed under a different light regime in phytochambers, we showed that these variations in PcISPS gene expression, measured by quantitative real-time polymerase chain reaction, are not only due to day-night changes, but also are linked to an internal circadian clock. Measurement of additional selected isoprenoid genes revealed that phytoene synthase (carotenoid pathway) displays similar fluctuations, whereas 1-deoxy-d-xylulose 5-phosphate reductoisomerase, possibly the first committed enzyme of the 1-deoxy-d-xylulose 5-phosphate pathway, only shows light regulation. On the protein level, it appeared that PcISPS activity and protein content became reduced under constant darkness, whereas under constant light, activity and protein content of this enzyme were kept high. In contrast, isoprene emission rates under continuous irradiation displayed circadian changes as is the case for gene expression of PcISPS. Furthermore, binding assays with Arabidopsis (Arabidopsis thaliana) late elongated hypocotyl, a transcription factor of Arabidopsis involved in circadian regulation, clearly revealed the presence of circadian-determining regulatory elements in the promoter region of PcISPS.

Loivamaki, Maaria; Louis, Sandrine; Cinege, Gyongyi; Zimmer, Ina; Fischbach, Robert J.; Schnitzler, Jorg-Peter

2007-01-01

261

[Tofisopam and melatonin attenuate the reorganization of circadian locomotor rhythm in rats under injection-induced stress conditions].  

PubMed

Repeated saline injections induce reorganization of the circadian locomotor rhythm in rats, which is manifested by increased amplitude, enhanced instability of the acrophase, and changed spectral characteristics. The benzodiazepine anxiolytic tofisopam (grandaxin, 10 mg/kg) and the pineal hormone melatonin (0.1 mg/kg) prevented the stress-induced changes in the circadian rhythm. The hormone exhibited a more optimal chronotropic activity than grandaxin. PMID:16845933

Arushunian, E B; Popov, A V

2006-01-01

262

It is not the parts, but how they interact that determines the behaviour of circadian rhythms across scales and organisms.  

PubMed

Biological rhythms, generated by feedback loops containing interacting genes, proteins and/or cells, time physiological processes in many organisms. While many of the components of the systems that generate biological rhythms have been identified, much less is known about the details of their interactions. Using examples from the circadian (daily) clock in three organisms, Neurospora, Drosophila and mouse, we show, with mathematical models of varying complexity, how interactions among (i) promoter sites, (ii) proteins forming complexes, and (iii) cells can have a drastic effect on timekeeping. Inspired by the identification of many transcription factors, for example as involved in the Neurospora circadian clock, that can both activate and repress, we show how these multiple actions can cause complex oscillatory patterns in a transcription-translation feedback loop (TTFL). Inspired by the timekeeping complex formed by the NMO-PER-TIM-SGG complex that regulates the negative TTFL in the Drosophila circadian clock, we show how the mechanism of complex formation can determine the prevalence of oscillations in a TTFL. Finally, we note that most mathematical models of intracellular clocks model a single cell, but compare with experimental data from collections of cells. We find that refitting the most detailed model of the mammalian circadian clock, so that the coupling between cells matches experimental data, yields different dynamics and makes an interesting prediction that also matches experimental data: individual cells are bistable, and network coupling removes this bistability and causes the network to be more robust to external perturbations. Taken together, we propose that the interactions between components in biological timekeeping systems are carefully tuned towards proper function. We also show how timekeeping can be controlled by novel mechanisms at different levels of organization. PMID:24904739

DeWoskin, Daniel; Geng, Weihua; Stinchcombe, Adam R; Forger, Daniel B

2014-06-01

263

It is not the parts, but how they interact that determines the behaviour of circadian rhythms across scales and organisms  

PubMed Central

Biological rhythms, generated by feedback loops containing interacting genes, proteins and/or cells, time physiological processes in many organisms. While many of the components of the systems that generate biological rhythms have been identified, much less is known about the details of their interactions. Using examples from the circadian (daily) clock in three organisms, Neurospora, Drosophila and mouse, we show, with mathematical models of varying complexity, how interactions among (i) promoter sites, (ii) proteins forming complexes, and (iii) cells can have a drastic effect on timekeeping. Inspired by the identification of many transcription factors, for example as involved in the Neurospora circadian clock, that can both activate and repress, we show how these multiple actions can cause complex oscillatory patterns in a transcription–translation feedback loop (TTFL). Inspired by the timekeeping complex formed by the NMO–PER–TIM–SGG complex that regulates the negative TTFL in the Drosophila circadian clock, we show how the mechanism of complex formation can determine the prevalence of oscillations in a TTFL. Finally, we note that most mathematical models of intracellular clocks model a single cell, but compare with experimental data from collections of cells. We find that refitting the most detailed model of the mammalian circadian clock, so that the coupling between cells matches experimental data, yields different dynamics and makes an interesting prediction that also matches experimental data: individual cells are bistable, and network coupling removes this bistability and causes the network to be more robust to external perturbations. Taken together, we propose that the interactions between components in biological timekeeping systems are carefully tuned towards proper function. We also show how timekeeping can be controlled by novel mechanisms at different levels of organization.

DeWoskin, Daniel; Geng, Weihua; Stinchcombe, Adam R.; Forger, Daniel B.

2014-01-01

264

Circadian activity rhythms and risk of incident dementia and MCI in older women  

PubMed Central

Objective Previous cross-sectional studies have observed alterations in activity rhythms in dementia patients but the direction of causation is unclear. We determined whether circadian activity rhythms measured in community-dwelling older women are prospectively associated with incident dementia or mild cognitive impairment (MCI). Method Activity rhythm data were collected from 1,282 healthy community-dwelling women from the Study of Osteoporotic Fractures cohort (mean age 83 years) with wrist actigraphy for a minimum of three 24-hour periods. Each participant completed a neuropsychological test battery and had clinical cognitive status (dementia, MCI, normal) adjudicated by an expert panel approximately 5 years later. All analyses were adjusted for demographics, BMI, functional status, depression, medications, alcohol, caffeine, smoking, health status, and co-morbidities. Results After 4.9 years of follow-up, 195 (15%) women had developed dementia and 302 (24%) had developed MCI. Older women with decreased activity rhythms had a higher likelihood of developing dementia or MCI when comparing those in the lowest quartiles of amplitude (Odds ratio[OR]=1.57,95% CI,1.09–2.25) or rhythm robustness (OR=1.57,95%CI,1.10–2.26) to women in the highest quartiles. An increased risk of dementia or MCI (OR=1.83,95% CI,1.29–2.61) was found for women whose timing of peak activity occurred later in the day (after 3:51PM) when compared to those with average timing (1:34PM–3:51PM). Interpretation Older, healthy women with decreased circadian activity rhythm amplitude and robustness, and delayed rhythms have increased odds of developing dementia and MCI. If confirmed, future studies should examine whether interventions (physical activity, bright light exposure) that influence activity rhythms will reduce the risk of cognitive deterioration in the elderly.

Tranah, Gregory J.; Blackwell, Terri; Stone, Katie L.; Ancoli-Israel, Sonia; Paudel, Misti L.; Ensrud, Kristine E.; Cauley, Jane A.; Redline, Susan; Hillier, Teresa A.; Cummings, Steven R; Yaffe, Kristine

2011-01-01

265

Systemic inflammation and circadian rhythm of cardiac autonomic modulation  

PubMed Central

Systemic inflammation (SI) is associated with impairment of cardiac autonomic modulation (CAM), which is associated with cardiac disease. However, there is limited data about SI on CAM circadian pattern, which this study is aimed to investigate in a middle-aged sample. C-reactive protein (CRP) was used as a SI marker. We performed HRV analysis on each 5-minute segment RRs from of a 24-hour 12-lead ECG to obtain time and frequency domain HRV indices as measures of CAM. The circadian pattern of CAM was analyzed by a two-stage modeling. Stage one, for each individual we fit a cosine periodic model based on the 288 segments of 5-minute HRV data to produce three individual-level cosine parameters that quantity the circadian pattern: mean (M), amplitude (Â), and acrophase time (?), measure the overall average, the amplitude of the oscillation, and the timing of the highest oscillation, respectively. Stage two, we used random-effects-meta-analysis to summarize the effects of CRP on the three circadian parameters obtained in stage one. CRP was adversely associated with lower M of log-HF, log-LF, SDNN, and RMSSD [? (SE): ?0.22 (0.07) ms2, ?0.20 (0.06) ms2, ?3.62 (0.99) ms, and ?2.32 (0.73) ms, respectively, with all p-values<0.01]. More importantly, CRP was also adversely associated with lower  of SDNN and RMSSD [? (SE): ?0.84 (0.44) ms and ?0.86 (0.38) ms, respectively, both p-values<0.05]. SI is adversely associated with circadian pattern of CAM, suggesting that the cardiac risk associated with SI may be partially mediated via inflammation-related changes in CAM.

Li, Xian; Shaffer, Michele L.; Rodriguez-Colon, Sol M.; He, Fan; Bixler, Edward O.; Vgontzas, Alexandros N.; Wolbrette, Deborah L.; Wu, Chuntao; Ball, Richard W.; Liao, Duanping

2011-01-01

266

From circadian clock gene expression to pathologies  

Microsoft Academic Search

In most organisms, circadian rhythms are generated by a molecular clockwork involving so-called clock genes. These circadian clock genes participate in regulatory feedback loops, in which proteins regulate their own expression. The outcome is that ribonucleic acids (RNAs) and proteins produced from many of these genes oscillate with a circadian rhythm. Here, we describe the regulation of clock genes and

Elaine Waddington Lamont; Francine O. James; Diane B. Boivin; Nicolas Cermakian

2007-01-01

267

Adult attention-deficit hyperactivity disorder is associated with alterations in circadian rhythms at the behavioural, endocrine and molecular levels.  

PubMed

Attention-deficit hyperactivity disorder (ADHD) in adults is associated with impaired sleep, and it has been postulated that this impairment may contribute to the psychopathology of this common condition. One key driver of sleep/wake cycles is the circadian system, which at the molecular level consists of a series of transcriptional feedback loops of clock genes, which in turn produce endocrine, physiological and behavioural outputs with a near 24 h periodicity. We set out to examine circadian rhythms at the behavioural, endocrine and molecular levels in ADHD. Adults with ADHD as well as age- and sex-matched controls were recruited. Circadian rhythms were measured by means of actigraphy for the determination of gross motor patterns, by self-sampling of oral mucosa for assessment of rhythmic expression of the clock genes BMAL1 and PER2, and by estimation of salivary cortisol and melatonin levels. Actigraphic analysis revealed significant diurnal and nocturnal hyperactivity in the ADHD group, as well as a significant shorter period of best fit for the locomotor circadian rhythm in ADHD. BMAL1 and PER2 showed circadian rhythmicity in controls with this being lost in the ADHD group. Cortisol rhythms were significantly phase delayed in the ADHD group. These findings indicate that adult ADHD is accompanied by significant changes in the circadian system, which in turn may lead to decreased sleep duration and quality in the condition. Further, modulation of circadian rhythms may represent a novel therapeutic avenue in the management of ADHD. PMID:22105622

Baird, A L; Coogan, A N; Siddiqui, A; Donev, R M; Thome, J

2012-10-01

268

CRY, a Drosophila Clock and Light-Regulated Cryptochrome, Is a Major Contributor to Circadian Rhythm Resetting and Photosensitivity  

Microsoft Academic Search

Light is a major environmental signal for circadian rhythms. We have identified and analyzed cry, a novel Drosophila cryptochrome gene. All characterized family members are directly photosensitive and include plant blue light photoreceptors. We show that cry transcription is under circadian regulation, influenced by the Drosophila clock genes period, timeless, Clock, and cycle. We also show that cry protein levels

Patrick Emery; W. Venus So; Maki Kaneko; Jeffrey C Hall; Michael Rosbash

1998-01-01

269

The influence of circadian rhythms on pre- and post-prandial metabolism in the snake Lamprophis fuliginosus  

Microsoft Academic Search

Abstract Measuring standard metabolic rate (SMR) and specific dynamic,action (SDA) has yielded insight into patterns of energy expenditure in snakes, but less emphasis has been placed on identifying metabolic variation and associated energy cost of circadian rhythms. To estimate SMR, SDA, and identify metabolic variation associated with circadian cycles in nocturnally active African house snakes (Lamprophis fuliginosus), we measured oxygen

J. h. Roe; ; W. A. Hopkins; J. w. Snodgrass; J. d. Congdon

270

The influence of circadian rhythms on pre- and post-prandial metabolism in the snake Lamprophis fuliginosus  

Microsoft Academic Search

Measuring standard metabolic rate (SMR) and specific dynamic action (SDA) has yielded insight into patterns of energy expenditure in snakes, but less emphasis has been placed on identifying metabolic variation and associated energy cost of circadian rhythms. To estimate SMR, SDA, and identify metabolic variation associated with circadian cycles in nocturnally active African house snakes (Lamprophis fuliginosus), we measured oxygen

J. H. Roe; W. A. Hopkins; J. W. Snodgrass; J. D. Congdon

2004-01-01

271

A statistical model of the human core-temperature circadian rhythm  

NASA Technical Reports Server (NTRS)

We formulate a statistical model of the human core-temperature circadian rhythm in which the circadian signal is modeled as a van der Pol oscillator, the thermoregulatory response is represented as a first-order autoregressive process, and the evoked effect of activity is modeled with a function specific for each circadian protocol. The new model directly links differential equation-based simulation models and harmonic regression analysis methods and permits statistical analysis of both static and dynamical properties of the circadian pacemaker from experimental data. We estimate the model parameters by using numerically efficient maximum likelihood algorithms and analyze human core-temperature data from forced desynchrony, free-run, and constant-routine protocols. By representing explicitly the dynamical effects of ambient light input to the human circadian pacemaker, the new model can estimate with high precision the correct intrinsic period of this oscillator ( approximately 24 h) from both free-run and forced desynchrony studies. Although the van der Pol model approximates well the dynamical features of the circadian pacemaker, the optimal dynamical model of the human biological clock may have a harmonic structure different from that of the van der Pol oscillator.

Brown, E. N.; Choe, Y.; Luithardt, H.; Czeisler, C. A.

2000-01-01

272

Evaluation of three circadian rhythm questionnaires with suggestions for an improved measure of morningness.  

PubMed

Circadian rhythms, cyclic fluctuations in many physiological and psychological functions, are thought to influence adjustment to shiftwork. A widely acknowledged individual difference in circadian rhythms, commonly called morningness, indicates preferences associated with morning or evening activities. Various self-report instruments have been developed to measure morningness, although little measurement data have been published for these scales. Because morningness scales are being used to select workers for night shiftwork, psychometric evaluations of these scales are needed. Psychometric assessments of undergraduate responses (N = 501) on three widely used scales indicate internal (interitem) measurement deficiencies in all three. Therefore, a 13-item scale was developed that distills the best items from two of these scales. Relationships between the new composite scale and external criteria are comparable with or stronger than similar relationships between the published scales and external criteria. PMID:2793773

Smith, C S; Reilly, C; Midkiff, K

1989-10-01

273

Effects of microgravity on circadian rhythms in insects  

NASA Technical Reports Server (NTRS)

The desert beetle Trigonoscelis gigas Reitt. was used as a biological model in studies that examined the effects of space flight on the circadian timing system. Results from studies aboard the Bion-10, Bion-11, and Photon-11 missions are reported. The control study is an ongoing Mir experiment. The studies indicate that the free-running period in beetles may be longer during space flight.

Alpatov, A. M.; Hoban-Higgins, T. M.; Fuller, C. A.; Lazarev, A. O.; Rietveld, W. J.; Tschernyshev, V. B.; Tumurova, E. G.; Wassmer, G.; Zotov, V. A.

1998-01-01

274

A time to think: Circadian rhythms in human cognition  

Microsoft Academic Search

Although peaks and troughs in cognitive performance characterize our daily functioning, time-of-day fluctuations remain marginally considered in the domain of cognitive psychology and neuropsychology. Here, we attempt to summarize studies looking at the effects of sleep pressure, circadian variations, and chronotype on cognitive functioning in healthy subjects. The picture that emerges from this assessment is that beyond physiological variables, time-of-day

Christina Schmidt; Fabienne Collette; Christian Cajochen; Philippe Peigneux

2007-01-01

275

Circadian rhythms in electrical circuits of Clivia miniata.  

PubMed

The biological clock regulates a wide range of physiological processes in plants. Here we show circadian variation of the Clivia miniata responses to electrical stimulation. The biologically closed electrochemical circuits in the leaves of C. miniata (Kaffir lily), which regulate its physiology, were analyzed in vivo using the charge stimulation method. The electrostimulation was provided with different voltages and electrical charges. Resistance between Ag/AgCl electrodes in the leaf of C. miniata was higher at night than during the day or the following day in the darkness. The biologically closed electrical circuits with voltage gated ion channels in C. miniata are activated the next day, even in the darkness. C. miniata memorizes daytime and nighttime. At continuous light, C. miniata recognizes nighttime and increases the input resistance to the nighttime value even under light. These results show that the circadian clock can be maintained endogenously and has electrochemical oscillators, which can activate voltage gated ion channels in biologically closed electrochemical circuits. The activation of voltage gated channels depends on the applied voltage, electrical charge and speed of transmission of electrical energy from the electrostimulator to the C. miniata leaves. We present the equivalent electrical circuits in C. miniata and its circadian variation to explain the experimental data. PMID:21546115

Volkov, Alexander G; Wooten, Joseph D; Waite, Astian J; Brown, Corydon R; Markin, Vladislav S

2011-10-15

276

The circadian rhythm of biochemical markers of bone resorption is normally synchronized in breast cancer patients with bone lytic metastases independently of tumor load  

Microsoft Academic Search

BackgroundBone metastases are devastating events resulting in disruption of local bone remodeling processes. Physiological bone turnover has a circadian rhythm. No data are available on the circadian pattern of bone turnover markers in patients with bone metastases.

Daniele Generali; Alfredo Berruti; Marco Tampellini; Andrea Dovio; Sara Tedoldi; Simone Bonardi; Marcello Tucci; Giovanni Allevi; Sergio Aguggini; Manuela Milani; Alberto Bottini; Luigi Dogliotti; Alberto Angeli

2007-01-01

277

Circadian rhythm disorder in a rare disease: Smith–Magenis syndrome  

Microsoft Academic Search

Smith–Magenis syndrome (SMS) is a clinically recognizable contiguous gene syndrome, caused by interstitial deletion of chromosome 17p11.2. The SMS phenotype include distinctive facial features, developmental delay and neurobehavioral abnormalities. The patients present major sleep disturbances ascribed to a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Treatment with morning beta-blockers and evening

Hélène De Leersnyder; Bruno Claustrat; Arnold Munnich; Alain Verloes

2006-01-01

278

The Pattern of the Circadian Rhythm of Pancreatic Secretion in Fed Pigs1  

Microsoft Academic Search

The pattern of the circadian rhythm of pancreatic secretion was studied in four 6- to 7-wk-old intact male pigs that were kept in metabolic cages under 12 h light:12 h dark cycles and fed three times a day at 0800, 1500, and 2200. Three 24-h collections of pancreatic juice and blood were begun at 0800 every 2nd day during 5

M.-J. Thaela; S. G. Pierzynowski; M. S. Jensen; K. Jakobsen; B. R. Westrom; B. W. Karlsson

2010-01-01

279

Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure  

NASA Technical Reports Server (NTRS)

1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

1996-01-01

280

Fatigue, sleep, and circadian rhythms prior to chemotherapy for breast cancer  

Microsoft Academic Search

Goals  Previous investigations have shown that women undergoing chemotherapy for breast cancer experience both disturbed sleep and fatigue. However, most of the previous research examined women either during or after chemotherapy. This study examined sleep, fatigue, and circadian rhythms in women with breast cancer before the start of chemotherapy.Patients and methods  Eighty five women with Stages I–IIIA breast cancer who were scheduled

Sonia Ancoli-Israel; Lianqi Liu; Matthew R. Marler; Barbara A. Parker; Vicky Jones; Georgia Robins Sadler; Joel Dimsdale; Mairav Cohen-Zion; Lavinia Fiorentino

2006-01-01

281

Toward a classification of medications for sleep and circadian rhythm disorders  

PubMed Central

While some systems classify medications according to therapeutic class, others are based on the mechanism of action of the drugs. The two main classifications of medications used to treat patients in the United States are those of the United States Pharmacopeia and US Food and Drug Administration, and they vary in their organization of the medication categories. Here we propose a taxonomy for medications used to treat sleep and circadian rhythm disorders based on symptoms and disorders.

Thorpy, Michael J; Roth, Thomas

2013-01-01

282

Effects of Vitamin B12 on Performance and Circadian Rhythm in Normal Subjects  

Microsoft Academic Search

This preliminary study investigates effects of methyl- and cyanocobalamin on circadian rhythms, well-being, alertness, and concentration in healthy subjects. Six women (mean age 35 years) and 14 men (mean age 37 years) were randomly assigned to treatment for 14 days with 3 mg cyano-(CB12) or methylcobalamin (MB12) after 9 days of pre-treatment observation. Levels in the CB12 group increased rapidly

Geert Mayer; Margarete Kröger; Karlheinz Meier-Ewert

1996-01-01

283

Light-sampling behavior in photoentrainment of a rodent circadian rhythm  

Microsoft Academic Search

Behavioral aspects of photoentrainment of circadian locomotor activity rhythms were recorded for a nocturnal den-dwelling rodent, the flying squirrel,Glaucomys volans. Methods included both telemetric monitoring and infrared observations of animals under constant dark (DD) or light-dark (LD) schedules in either standard wheel cages or in newly developed simulated den cages. By means of the den cages, several aspects of a

Patricia J. DeCoursey

1986-01-01

284

Circadian Rhythms in the CNS and Peripheral Clock Disorders: Human Sleep Disorders and Clock Genes  

Microsoft Academic Search

Genetic analyses of circadian rhythm sleep disorders (CRSD), such as familial advanced sleep phase syndrome (ASPS) and delayed sleep phase syndrome (DSPS), and morningness-eveningness revealed the relationship between variations in clock genes and diurnal change in human behaviors. Variations such as T3111C in the Clock gene are reportedly associated with morningness-eveningness. Two of the pedigrees of familial ASPS (FASPS) are

Takashi Ebisawa

2007-01-01

285

Influence of deuterium oxide on circadian activity rhythms of hamsters: role of the suprachiasmatic nuclei.  

PubMed

The period of the free-running circadian activity rhythm of Syrian hamsters was measured before and during treatment with 10% deuterium oxide (D2O). Deuteration increased period length by approximately 0.5 h per cycle both pre- and postoperatively in hamsters sustaining complete, incomplete or no unilateral lesions of the suprachiasmatic nuclei (SCN). Neither coupling between the bilaterally paired SCN, nor elimination of 50% of SCN tissue affected period length during D2O treatment. However, variability of the response to D2O was much greater in lesioned than in intact hamsters. We propose that a small percentage of the normal complement of SCN neurons is sufficient to permit full responsiveness of the circadian system to D2O and that there is substantial redundancy in the neural system that responds to deuterium. Stability of the circadian system appears to be increased by the full complement of SCN neurons. PMID:3013372

Pickard, G E; Zucker, I

1986-06-18

286

Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field.  

PubMed

Biological clocks have evolved as an adaptation to life on a rhythmic planet, synchronising physiological processes to the environmental light-dark cycle. Here we examine circadian clock function in Mexican blind cavefish Astyanax mexicanus and its surface counterpart. In the lab, adult surface fish show robust circadian rhythms in per1, which are retained in cave populations, but with substantial alterations. These changes may be due to increased levels of light-inducible genes in cavefish, including clock repressor per2. From a molecular standpoint, cavefish appear as if they experience 'constant light' rather than perpetual darkness. Micos River samples show similar per1 oscillations to those in the lab. However, data from Chica Cave shows complete repression of clock function, while expression of several light-responsive genes is raised, including DNA repair genes. We propose that altered expression of light-inducible genes provides a selective advantage to cavefish at the expense of a damped circadian oscillator. PMID:24225650

Beale, Andrew; Guibal, Christophe; Tamai, T Katherine; Klotz, Linda; Cowen, Sophie; Peyric, Elodie; Reynoso, Víctor H; Yamamoto, Yoshiyuki; Whitmore, David

2013-01-01

287

Sleep and circadian rhythms in long duration space flight - Antarctica as an analogue environment  

NASA Technical Reports Server (NTRS)

The feasibility of using Antarctica as an environment for studying the impact of unusual 24 h environmental cycles (zeitgebers) on the circadian system is discussed. Adaptation of circadian rhythms and sleep of three scientists travelling from New Zealand to Antarctica during summer (which is analogous to arrival at a lunar base during the lunar day) has been studied. Data obtained indicate that sleep occurred at the same clock time, but sleep quality was poorer in Antarctica, which can be explained by the fact that the circadian system delayed by about 2 h in Antarctica, as would be expected in a weaker zeitgeber environment. It is suggested that sleep could be improved by altering patterns of exposure to the available zeitgebers to increase their effective strength.

Gander, Philippa H.

1992-01-01

288

Cognitive Performance as a Zeitgeber: Cognitive Oscillators and Cholinergic Modulation of the SCN Entrain Circadian Rhythms  

PubMed Central

The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals that can synchronize or entrain to environmental cues. Although light exerts powerful influences on SCN output, other non-photic stimuli can modulate the SCN as well. We recently demonstrated that daily performance of a cognitive task requiring sustained periods of attentional effort that relies upon basal forebrain (BF) cholinergic activity dramatically alters circadian rhythms in rats. In particular, normally nocturnal rats adopt a robust diurnal activity pattern that persists for several days in the absence of cognitive training. Although anatomical and pharmacological data from non-performing animals support a relationship between cholinergic signaling and circadian rhythms, little is known about how endogenous cholinergic signaling influences SCN function in behaving animals. Here we report that BF cholinergic projections to the SCN provide the principal signal allowing for the expression of cognitive entrainment in light-phase trained animals. We also reveal that oscillator(s) outside of the SCN drive cognitive entrainment as daily timed cognitive training robustly entrains SCN-lesioned arrhythmic animals. Ablation of the SCN, however, resulted in significant impairments in task acquisition, indicating that SCN-mediated timekeeping benefits new learning and cognitive performance. Taken together, we conclude that cognition entrains non-photic oscillators, and cholinergic signaling to the SCN serves as a temporal timestamp attenuating SCN photic-driven rhythms, thereby permitting cognitive demands to modulate behavior.

Gritton, Howard J.; Stasiak, Ashley M.; Sarter, Martin; Lee, Theresa M.

2013-01-01

289

An emerging role for Cullin-3 mediated ubiquitination in sleep and circadian rhythm: insights from Drosophila.  

PubMed

Although the neurophysiological correlates of sleep have been thoroughly described, genetic mechanisms that control sleep architecture, long surmised from ethological studies, family histories and clinical observations, have only been investigated during the past decade. Key contributions to the molecular understanding of sleep have come from studies in Drosophila, benefitting from a strong history of circadian rhythm research. For instance, a number of recent papers have highlighted the role of the E3 ubiquitin ligase Cullin-3 in the regulation of circadian rhythm and sleep. We propose that different Cullin-3 substrate adaptors may affect specific molecular pathways and diverse aspects of circadian rhythm and sleep. We have previously shown that mutations in BTBD9, a risk factor for Restless Legs Syndrome (RLS) encoding a Cullin-3 substrate adaptor, lead to reduced dopamine, increased locomotion and sleep fragmentation. Here, we propose that Cullin-3 acts together with BTBD9 to limit the accumulation of iron regulatory proteins in conditions of iron deficiency. Our model is consistent with clinical observations implicating iron homeostasis in the pathophysiology of RLS and predicts that lack of BTBD9 leads to misregulation of cellular iron storage, inactivating the critical biosynthetic enzyme Tyrosine Hydroxylase in dopaminergic neurons, with consequent phenotypic effects on sleep. PMID:23455037

Freeman, Amanda A H; Mandilaras, Konstantinos; Missirlis, Fanis; Sanyal, Subhabrata

2013-01-01

290

Circadian rhythm of salivary cortisol, plasma cortisol, and plasma ACTH in end-stage renal disease  

PubMed Central

Objective Patients with end-stage renal disease (ESRD) can display the features of endogenous hypercortisolism but are difficult to evaluate for Cushing's syndrome. We evaluated the circadian rhythm of plasma compared with salivary cortisol in subjects with ESRD. Design Plasma and salivary cortisol and plasma ACTH samples were drawn frequently over 24?h in an inpatient research unit in stable ESRD subjects on daytime chronic hemodialysis (n=16) vs controls (n=8). Methods Plasma cortisol was measured every 2?h from 0800 to 0600?h the following day. Salivary cortisol was measured every 2?h, except between 2400 and 0400?h (sleep time). Plasma ACTH measured in a subset of samples and C-reactive protein (CRP) was measured as a marker of a subclinical inflammatory state in all subjects. Results ESRD subjects had a discernable circadian rhythm in plasma and salivary cortisol, but with a significantly higher nadir (1800–2400?h) compared with the controls (P=0.016–<0.001). After excluding four ESRD subjects without a normal circadian rhythm, the ESRD subjects still had higher nadir plasma and salivary cortisol and plasma ACTH compared with controls. There was no difference in the correlation of salivary and plasma cortisol in control vs ESRD subjects. ESRD subjects had higher CRP levels compared with controls. Conclusions ESRD subjects had increased late-night plasma and salivary cortisol and plasma ACTH levels. Late-night salivary cortisol is a reliable index of plasma cortisol in ESRD patients.

Raff, Hershel; Trivedi, Hariprasad

2012-01-01

291

Chronoendocrinological studies in athletes. Circadian rhythms of T3, TSH, cortisol and testosterone.  

PubMed

Endocrine functions were studied in 83 healthy athletes, maintained under normal light-dark conditions, with normal activity-sleep patterns. In these subjects statistically significant circadian rhythms of T3, TSH, cortisol (CSL) and testosterone (T) were found; for each hormone two or three different types of circadian rhythm (with peaks of acrophase between: 6.30 a.m. and 1.30 a.m., 1.30 p.m. and 10.30 p.m., 10.30 p.m. and 6.30 p.m.) were observed. The following correlations have been demonstrated between the length of participation (in years) in performance sports and the mean circadian blood hormone concentration: a negative one for CSL (p less than 0.01) and a positive one for TSH (p less than 0.05). An increase of the mean circadian values of T concentration in venous blood was found in females fencers (n = 9). PMID:506751

Dobrza?ski, T; Zurowski, S; Kempnerska, O; Graban, W

1979-01-01

292

Dissociation of body-temperature and melatonin secretion circadian rhythms in patients with chronic fatigue syndrome.  

PubMed

Many patients with chronic fatigue syndrome (CFS) display features of hypothalamic dysfunction. We have investigated aspects of circadian rhythmicity, an important hypothalamic function, in 20 CFS patients and in 17 age- and sex-matched healthy control subjects. There were no differences between the two groups in the amplitude, mesor (mean value) or timing of the peak (acrophase) of the circadian rhythm of core temperature, or in the timing of the onset of melatonin secretion. However, the CFS patients showed no significant correlation between the timing of the temperature acrophase and the melatonin onset (P < 0.5), whereas the normal significant correlation was observed in the controls (P < 0.05). Dissociation of circadian rhythms could be due to the sleep deprivation and social disruption, and/or the reduction in physical activity which typically accompany CFS. By analogy with jet-lag and shift-working, circadian dysrhythmia could be an important factor in initiating and perpetuating the cardinal symptoms of CFS, notably tiredness, impaired concentration and intellectual impairment. PMID:8842569

Williams, G; Pirmohamed, J; Minors, D; Waterhouse, J; Buchan, I; Arendt, J; Edwards, R H

1996-07-01

293

Scheduled Daily Mating Induces Circadian Anticipatory Activity Rhythms in the Male Rat  

PubMed Central

Daily schedules of limited access to food, palatable high calorie snacks, water and salt can induce circadian rhythms of anticipatory locomotor activity in rats and mice. All of these stimuli are rewarding, but whether anticipation can be induced by neural correlates of reward independent of metabolic perturbations associated with manipulations of food and hydration is unclear. Three experiments were conducted to determine whether mating, a non-ingestive behavior that is potently rewarding, can induce circadian anticipatory activity rhythms in male rats provided scheduled daily access to steroid-primed estrous female rats. In Experiment 1, rats anticipated access to estrous females in the mid-light period, but also exhibited post-coital eating and running. In Experiment 2, post-coital eating and running were prevented and only a minority of rats exhibited anticipation. Rats allowed to see and smell estrous females showed no anticipation. In both experiments, all rats exhibited sustained behavioral arousal and multiple mounts and intromissions during every session, but ejaculated only every 2–3 days. In Experiment 3, the rats were given more time with individual females, late at night for 28 days, and then in the midday for 28 days. Ejaculation rates increased and anticipation was robust to night sessions and significant although weaker to day sessions. The anticipation rhythm persisted during 3 days of constant dark without mating. During anticipation of nocturnal mating, the rats exhibited a significant preference for a tube to the mating cage over a tube to a locked cage with mating cage litter. This apparent place preference was absent during anticipation of midday mating, which may reflect a daily rhythm of sexual reward. The results establish mating as a reward stimulus capable of inducing circadian rhythms of anticipatory behavior in the male rat, and reveal a critical role for ejaculation, a modulatory role for time of day, and a potential confound role for uncontrolled food intake.

Landry, Glenn J.; Opiol, Hanna; Marchant, Elliott G.; Pavlovski, Ilya; Mear, Rhiannon J.; Hamson, Dwayne K.; Mistlberger, Ralph E.

2012-01-01

294

A sequential program of dual phosphorylation of KaiC as a basis for circadian rhythm in cyanobacteria  

PubMed Central

The circadian phosphorylation cycle of the cyanobacterial clock protein KaiC has been reconstituted in vitro. The phosphorylation profiles of two phosphorylation sites in KaiC, serine 431 (S431) and threonine 432 (T432), revealed that the phosphorylation cycle contained four steps: (i) T432 phosphorylation; (ii) S431 phosphorylation to generate the double-phosphorylated form of KaiC; (iii) T432 dephosphorylation; and (iv) S431 dephosphorylation. We then examined the effects of mutations introduced at one KaiC phosphorylation site on the intact phosphorylation site. We found that the product of each step in the phosphorylation cycle regulated the reaction in the next step, and that double phosphorylation converted KaiC from an autokinase to an autophosphatase, whereas complete dephosphorylation had the opposite effect. These mechanisms serve as the basis for cyanobacterial circadian rhythm generation. We also found that associations among KaiA, KaiB, and KaiC result from S431 phosphorylation, and these interactions would maintain the amplitude of the rhythm.

Nishiwaki, Taeko; Satomi, Yoshinori; Kitayama, Yohko; Terauchi, Kazuki; Kiyohara, Reiko; Takao, Toshifumi; Kondo, Takao

2007-01-01

295

Aberrant Development of the Suprachiasmatic Nucleus and Circadian Rhythms in Mice Lacking the Homeodomain Protein Six6  

PubMed Central

The suprachiasmatic nucleus (SCN) of the mammalian hypothalamus is the central pacemaker for peripheral and organismal circadian rhythms. The development of this hypothalamic structure depends on genetic programs throughout embryogenesis. We have investigated the role of the homeodomain transcription factor Six6 in the development of the SCN. We first showed that Six6 mRNA has circadian regulation in the mouse SCN. We then characterized the behavioral activity patterns of Six6-null mice under various photoperiod manipulations and stained their hypothalami using SCN-specific markers. Six6-null mice display abnormal patterns of circadian behavior indicative of SCN abnormalities. The ability of light exposure to reset rhythms correlates with the presence or absence of optic nerves, but all Six6-null mice show irregular rhythms. In contrast, wild-type mice with crushed optic nerves maintain regular rhythms regardless of light exposure. Using immunohistochemistry for arginine vasopressin (AVP), vasoactive intestinal polypeptide (VIP), and ?-galactosidase, we demonstrated the lack of these SCN markers in all Six6- null mice regardless of the presence of optic nerve or partial circadian rhythms. Therefore, Six6 is required for the normal development of the SCN, and the Six6-null mouse can mount independent, although irregular, circadian rhythms despite the apparent absence of a histochemically defined SCN.

Clark, Daniel D.; Gorman, Michael R.; Hatori, Megumi; Meadows, Jason D.; Panda, Satchidananda; Mellon, Pamela L.

2013-01-01

296

Effects of prd circadian clock mutations on FRQ-less rhythms in Neurospora.  

PubMed

Rhythmic conidiation (spore formation) in Neurospora crassa provides a model system for investigating the molecular mechanisms of circadian rhythmicity. A feedback loop involving the frq, wc-1, and wc-2 gene products (FRQ/ WCC) is an important component of the mechanism; however, rhythmic conidiation can still be observed when these gene products are absent. The nature of the oscillator(s) that drives this FRQ-less rhythmicity (FLO) is an important question in Neurospora circadian biology. We have looked for interactions between FRQ/WCC and FLO by assaying the effects on FRQ-less rhythms of mutations known to affect the period in the presence of FRQ. We assayed 4 prd mutations (prd-1, prd-2, prd-3, and prd-4) under 2 conditions in frq(null) strains: long-period free-running rhythms in chol-1 strains grown without choline, and heat-entrainable rhythms in choline-sufficient conditions. We found effects of all 4 mutations on both types of FRQ-less rhythms. The greatest effects were seen with prd-1 and prd-2, which abolished free-running rhythms in the chol-1; frq(10) backgrounds and significantly affected entrained peak timing under heat-entrainment conditions in frq( 10) backgrounds. The prd-3 and prd-4 mutations had more subtle effects on period and stability of free-running rhythms in the chol-1; frq(10) backgrounds and had little effect on peak timing under heat-entrainment conditions in frq(10) backgrounds. These results, along with previously published evidence for effects of prd mutations on other FRQ-less rhythms, suggest that either there are common components shared between the FRQ/WCC oscillator and several FRQ-less oscillators or that there is a single oscillator driving all conidiation rhythms. We favor a model of the Neurospora circadian system in which a single FRQ-less oscillator drives conidiation and interacts with the FRQ/WCC feedback loop; the output or amplitude of the FRQ-less oscillator can be affected by many gene products and metabolic conditions that reveal FRQ-less rhythmicity. We propose that prd-1 and prd-2 are good candidates for components of the FRQ-less oscillator and that prd-3 and prd-4 act on the system mainly through effects on FRQ/WCC. PMID:20348458

Li, Sanshu; Lakin-Thomas, Patricia

2010-04-01

297

[Circadian rhythms of 11-hydroxycorticosteroid excretion in rats administered cortisol at different times of the day].  

PubMed

Male Wistar rats housed under the conditions of 12L : 12D, 24 +/- 1 degree C and free access to food and water received isotonic sodium chloride solution or cortisol in doses of 2 and 4 mg/kg, respectively. Daily stress or cortisol injections in the morning or evening are the synchronizers of 11-hydroxycorticosteroid excretion rhythm. Morning stress leads to the increase of the 12-hour rhythm. On the contrary, evening stress or cortisol administration during maximal endogenous secretion of corticosteroids are associated with the elevation of circadian periodicity. Exogenic changes in the rhythmic organization of the hypothalamo-hypophyseal-adrenocortical system are followed by activation of adaptive processes involved in the normalization of the initially modified glucocorticoid rhythm. PMID:6683573

Mel'nikov, V N; Shorin, Iu P

1983-07-01

298

Masking of the circadian rhythms of heart rate and core temperature by the rest-activity cycle in man  

NASA Technical Reports Server (NTRS)

Experiments were conducted to estimate the magnitude of the masking effect produced in humans by alternate periods of physical activity and rest or sleep on the circadian rhythms of heart rate and core temperature. The heart rate, rectal temperature, and nondominant wrist activity were monitored in 12 male subjects during 6 days of normal routine at home and during 6 days of controlled bed-rest regimen. The comparisons of averaged waveforms for the activity, heart rate, and temperature indicated that about 45 percent of the range of the circadian heart rate rhythm during normal routine and about 14 percent of the range of the circadian temperature rhythm were attributable to the effects of activity. The smaller effect of activity on the temperature rhythm may be partially attributable to the fact that core temperature is being more rigorously conserved than heart rate, at least during moderate exercise.

Gander, Philippa H.; Connell, Linda J.; Graeber, R. Curtis

1986-01-01

299

Convergent Rhythm Generation from Divergent Cellular Mechanisms  

PubMed Central

Different modulatory inputs commonly elicit distinct rhythmic motor patterns from a central pattern generator (CPG), but they can instead elicit the same pattern. We are determining the rhythm-generating mechanisms in this latter situation, using the gastric mill (chewing) CPG in the crab (Cancer borealis) stomatogastric ganglion, where stimulating the projection neuron MCN1 (modulatory commissural neuron 1) or bath applying CabPK (C. borealis pyrokinin) peptide elicits the same gastric mill motor pattern, despite configuring different gastric mill circuits. In both cases, the core rhythm generator includes the same reciprocally inhibitory neurons LG (lateral gastric) and Int1 (interneuron 1), but the pyloric (food-filtering) circuit pacemaker neuron AB (anterior burster) is additionally necessary only for CabPK rhythm generation. MCN1 drives this rhythm generator by activating in the LG neuron the modulator-activated inward current (IMI), which waxes and wanes periodically due to phasic feedback inhibition of MCN1 transmitter release. Each buildup of IMI enables the LG neuron to generate a self-terminating burst and thereby alternate with Int1 activity. Here we establish that CabPK drives gastric mill rhythm generation by activating in the LG neuron IMI plus a slowly activating transient, low-threshold inward current (ITrans-LTS) that is voltage, time, and Ca2+ dependent. Unlike MCN1, CabPK maintains a steady IMI activation, causing a subthreshold depolarization in LG that facilitates a periodic postinhibitory rebound burst caused by the regular buildup and decay of the availability of ITrans-LTS. Thus, different modulatory inputs can use different rhythm-generating mechanisms to drive the same neuronal rhythm. Additionally, the same ionic current (IMI) can play different roles under these different conditions, while different currents (IMI, ITrans-LTS) can play the same role.

Rodriguez, Jason C.; Blitz, Dawn M.

2013-01-01

300

Manipulating the sleep-wake cycle and circadian rhythms to improve clinical management of major depression  

PubMed Central

Background Clinical psychiatry has always been limited by the lack of objective tests to substantiate diagnoses and a lack of specific treatments that target underlying pathophysiology. One area in which these twin failures has been most frustrating is major depression. Due to very considerable progress in the basic and clinical neurosciences of sleep-wake cycles and underlying circadian systems this situation is now rapidly changing. Discussion The development of specific behavioral or pharmacological strategies that target these basic regulatory systems is driving renewed clinical interest. Here, we explore the extent to which objective tests of sleep-wake cycles and circadian function - namely, those that measure timing or synchrony of circadian-dependent physiology as well as daytime activity and nighttime sleep patterns - can be used to identify a sub-class of patients with major depression who have disturbed circadian profiles. Summary Once this unique pathophysiology is characterized, a highly personalized treatment plan can be proposed and monitored. New treatments will now be designed and old treatments re-evaluated on the basis of their effects on objective measures of sleep-wake cycles, circadian rhythms and related metabolic systems.

2013-01-01

301

Effects of (+/-) 3,4-methylenedioxymethamphetamine (MDMA) on sleep and circadian rhythms.  

PubMed

Abuse of stimulant drugs invariably leads to a disruption in sleep-wake patterns by virtue of the arousing and sleep-preventing effects of these drugs. Certain stimulants, such as 3,4-methylenedioxymethamphetamine (MDMA), may also have the potential to produce persistent alterations in circadian regulation and sleep because they can be neurotoxic toward brain monoaminergic neurons involved in normal sleep regulation. In particular, MDMA has been found to damage brain serotonin (5-HT) neurons in a variety of animal species, including nonhuman primates, with growing evidence that humans are also susceptible to MDMA-induced brain 5-HT neurotoxicity. 5-HT is an important modulator of sleep and circadian rhythms and, therefore, individuals who sustain MDMA-induced 5-HT neurotoxicity may be at risk for developing chronic abnormalities in sleep and circadian patterns. In turn, such abnormalities could play a significant role in other alterations reported in abstinent in MDMA users (e.g., memory disturbance). This paper will review preclinical and clinical studies that have explored the effects of prior MDMA exposure on sleep, circadian activity, and the circadian pacemaker, and will highlight current gaps in knowledge and suggest areas for future research. PMID:17982598

McCann, Una D; Ricaurte, George A

2007-01-01

302

Food-entrained circadian rhythms are sustained in arrhythmic Clk/Clk mutant mice.  

PubMed

Daily scheduled feeding is a potent time cue that elicits anticipatory activity in rodents. This food-anticipatory activity (FAA) is controlled by a food-entrainable oscillator (FEO) that is distinct from light-entrained oscillators of the suprachiasmatic nucleus (SCN). Circadian rhythms within the SCN depend on transcription-translation feedback loops in which CLOCK protein is a key positive regulator. The Clock gene is expressed in rhythmic tissues throughout the brain and periphery, implicating its widespread involvement in the functioning of circadian oscillators. To examine whether CLOCK protein is also necessary for the FEO, the effect of daily food restriction was studied in homozygous Clock mutant (Clk/Clk) mice. The results show that Clk/Clk mutant mice exhibit FAA, even when their circadian wheel-running behavior is arrhythmic. As in wild-type controls, FAA in Clk/Clk mutants persists after temporal feeding cues are removed for several cycles, indicating that the FEO is a circadian timer. This is the first demonstration that the Clock gene is not necessary for the expression of a circadian, food-entrained behavior and suggests that the FEO is mediated by a molecular mechanism distinct from that of the SCN. PMID:12649127

Pitts, SiNae; Perone, Elizabeth; Silver, Rae

2003-07-01

303

Pigment-dispersing factor affects nocturnal activity rhythms, photic entrainment, and the free-running period of the circadian clock in the cricket gryllus bimaculatus.  

PubMed

Pigment-dispersing factor (PDF) is a neuropeptide widely distributed in insect brains and plays important roles in the circadian system. In this study, we used RNA interference to study the role of the pigment-dispersing factor (pdf) gene in regulating circadian locomotor rhythms in the cricket, Gryllus bimaculatus. Injections of pdf double-stranded RNA (dspdf) effectively knocked down the pdf mRNA and PDF peptide levels. The treated crickets maintained the rhythm both under light-dark cycles (LD) and constant darkness (DD). However, they showed rhythms with reduced nocturnal activity with prominent peaks at lights-on and lights-off. Entrainability of dspdf-injected crickets was higher than control crickets as they required fewer cycles to resynchronize to the LD cycles shifted by 6 h. The free-running periods of the dspdf-injected crickets were shorter than those of control crickets in DD. These results suggest that PDF is not essential for the rhythm generation but involved in control of the nocturnality, photic entrainment, and fine tuning of the free-running period of the circadian clock. PMID:21252361

Hassaneen, Ehab; El-Din Sallam, Alaa; Abo-Ghalia, Ahmad; Moriyama, Yoshiyuki; Karpova, Svetlana G; Abdelsalam, Salah; Matsushima, Ayami; Shimohigashi, Yasuyuki; Tomioka, Kenji

2011-02-01

304

The emergence of the cortisol circadian rhythm in monozygotic and dizygotic twin infants: the twin-pair synchrony  

PubMed Central

Objective Studies on the influence of genetic factors on the ontogeny of cortisol circadian rhythm in infants are lacking. This study evaluated the influence of twinning and the heritability on the age of emergence of salivary cortisol rhythm. Design and subjects A longitudinal study was performed using salivary samples obtained during morning and night, at 2, 4, 8, 12, 16, 20 and 24 weeks of postnatal life in 34 infants, 10 monozygotic (MZ) and 7 dizygotic (DZ) twin pairs. Salivary cortisol was determined by radioimmunoassay (RIA). Zigosity was verified by DNA analysis of at least 13 short tandem repeat polymorphisms. Difference of the emergence of cortisol circadian rhythm, within each twin pair, the intraclass correlation coefficient and the heritability index (h2) were calculated. Results The mean (± SEM) age of emergence of salivary cortisol circadian rhythm was similar in MZ and DZ (7·8 ± 1·0 vs 7·4 ± 1·3 weeks). Seven pairs showed coincidence of the emergence of cortisol rhythm. Ten pairs were not coincident; among them the within-pair difference of emergence of salivary circadian rhythm was similar in both MZ and DZ groups. The intraclass correlation coefficients were rMZ = 0·60, P = 0·02; and rDZ = 0·65, P = 0·03, respectively. The heritability index (h2) was 0·21 (ns). Conclusions Salivary circadian rhythm appeared at the same postnatal age in MZ and DZ twin infants. Although several physiological aspects might be involved, the heritability index, obtained in the present study, suggests less genetic than environmental impact on the age of the onset of the cortisol circadian rhythm. Our data also indicated that each twin-pair show synchrony because they probably shared prenatal and postnatal environmental synchronizers.

Custodio, Rodrigo Jose; Junior, Carlos Eduardo Martinelli; Milani, Soraya Lopes Sader; Simoes, Aguinaldo Luis; de Castro, Margaret; Moreira, Ayrton Custodio

2007-01-01

305

The Effects of Hydrogen Peroxide on the Circadian Rhythms of Microcystis aeruginosa  

PubMed Central

Background The cyanobacterium Microcystis aeruginosa is one of the principal bloom-forming cyanobacteria present in a wide range of freshwater ecosystems. M. aeruginosa produces cyanotoxins, which can harm human and animal health. Many metabolic pathways in M. aeruginosa, including photosynthesis and microcystin synthesis, are controlled by its circadian rhythms. However, whether xenobiotics affect the cyanobacterial circadian system and change its growth, physiology and biochemistry is unknown. We used real-time PCR to study the effect of hydrogen peroxide (H2O2) on the expression of clock genes and some circadian genes in M. aeruginosa during the light/dark (LD) cycle. Results The results revealed that H2O2 changes the expression patterns of clock genes (kaiA, kaiB, kaiC and sasA) and significantly decreases the transcript levels of kaiB, kaiC and sasA. H2O2 treatment also decreased the transcription of circadian genes, such as photosynthesis-related genes (psaB, psbD1 and rbcL) and microcystin-related genes (mcyA, mcyD and mcyH), and changed their circadian expression patterns. Moreover, the physiological functions of M. aeruginosa, including its growth and microcystin synthesis, were greatly influenced by H2O2 treatment during LD. These results indicate that changes in the cyanobacterial circadian system can affect its physiological and metabolic pathways. Conclusion Our findings show that a xenobiotic can change the circadian expression patterns of its clock genes to influence clock-controlled gene regulation, and these influences are evident at the level of cellular physiology.

Yu, Shuqiong; Pan, Xiangjie; Wu, Tao; Fu, Zhengwei

2012-01-01

306

Contribution of C3 carboxylation to the circadian rhythm of carbon dioxide uptake in a Crassulacean acid metabolism plant Kalanchoë daigremontiana.  

PubMed

During the endogenous circadian rhythm of carbon dioxide uptake in continuous light by a Crassula cean acid metabolism plant, Kalanchoë daigremontiana, the two carboxylating enzymes, phosphoenolpyruvate carboxylase (PEPC) and ribulose 1,5 bisphosphate carboxylase/oxygenase (Rubisco), are active simultaneously, although, until now, only the role of PEPC in generating the rhythm has been acknowledged. According to the established model, the rhythm is primarily regulated at the PEPC activity level, modulated by periodic compartmentation of its inhibitor, malate, in the vacuole and controlled by tension/relaxation of the tonoplast. However, the circadian accumulation of malic acid (the main indicator of PEPC activity) dampened significantly within the first few periods without affecting the rhythm's amplitude. Moreover, the amount of malate accumulated during a free-running oscillation was several-fold lower than the amount expected if PEPC were the key carboxylating enzyme, based on a 1:1 stoichiometry of CO(2) and malate. Together with the observation that rates of CO(2) uptake under continuous light were higher than in darkness, the evidence shows that C(3) carboxylation greatly contributes to the generation of rhythmic CO(2) uptake in continuous light in this 'obligate' CAM plant. Because the shift from predominantly CAM to predominantly C(3) carboxylation is smooth and does not distort the trajectory of the rhythm, its control probably arises from a robust network of oscillators, perhaps also involving stomata. PMID:12709493

Wyka, Tomasz P; Lüttge, Ulrich E

2003-05-01

307

Circadian rhythm of mechanically mediated differentiation of osteoblasts  

NASA Technical Reports Server (NTRS)

The differential of osteoblasts in response to orthodontic pressure in the periodontal ligament of the maxillary-first-molar periodontal ligaments of 12-h-light/dark-entrained 7-wk-old male Simonsen outbred rats is measured by (H-3)-Thymidine nuclear-volume morphometry (Roberts et al., 1983) at hourly intervals throughout the circadian cycle. The results are presented in graphs and discussed. Preosteoblast large nuclei (D-cells) are found to synthesize DNA mainly in light and to divide in the following dark period, while small-nucleus osteoprogenitors (A-cells) synthesize in darkness and divide in light. These findings are seen as consistent with a model in which the sequence of proliferation and differentiation requires at least 60 h (five 12-h periods) and the shift from A to D cells lasts about 19 h.

Roberts, W. E.; Mozsary, P. G.; Klingler, E.

1984-01-01

308

Effects of bile acid administration on bile acid synthesis and its circadian rhythm in man  

SciTech Connect

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from (26-14C)cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bile acid synthesis in man.

Pooler, P.A.; Duane, W.C.

1988-09-01

309

Effects of light, food, and methamphetamine on the circadian activity rhythm in mice.  

PubMed

The circadian rhythm of locomotor activity in mice is synchronized to environmental factors such as light and food availability. It is well-known that entrainment of the activity rhythm to the light-dark cycle is attained by the circadian pacemaker in the suprachiasmatic nucleus (SCN). Locomotor activity is also controlled by two extra-SCN oscillators; periodic food availability entrains the food-entrainable oscillator (FEO) and constant consumption of low-dose methamphetamine reveals the output of the methamphetamine-sensitive circadian oscillator (MASCO). In this study, we sought to investigate the relationship between the SCN, FEO, and MASCO by examining the combinatorial effects of light, food restriction, and/or methamphetamine on locomotor activity. To investigate coupling between the SCN and FEO, we tested whether food anticipatory activity, which is the output of the FEO, shifted coordinately with phase shifts of the light-dark cycle. We found that the phase of food anticipatory activity was phase-delayed or phase-advanced symmetrically with the respective shift of the light-dark cycle, suggesting that the FEO is strongly coupled to the SCN and the phase angle between the SCN and FEO is maintained during ad libitum feeding. To examine the effect of methamphetamine on the output of the FEO, we administered methamphetamine to mice undergoing restricted feeding and found that food-entrained activity was delayed by methamphetamine treatment. In addition, restricted feeding induced dissociation of the MASCO and SCN activity rhythms during short-term methamphetamine treatment, when these rhythms are typically integrated. In conclusion, our data suggest that the outputs of the SCN, FEO and MASCO collectively drive locomotor activity. PMID:24530262

Pendergast, Julie S; Yamazaki, Shin

2014-04-10

310

[Peculiarities of circadian rhythms in plants from different geographical latitudes].  

PubMed

1 Two species of plants (Taraxacum arcticum and Arnica angustifolia), collected in Spitsbergen (geogr. latitude 76-80 degrees) exhibit endogenous circadian leaf movements but also movements with shorter periods. Astragalus frigidus, A. alpinus and Hedysarum hedysaroides, collected in arctic regions of continental Europe, also show endogenous diurnal leaf movements. 2. In most of the species tested, there was no difference in the length of the free running periods of plants from arctic and Central-European regions. This is also the case when individuals of the same species collected in different regions are compared. However, in Taraxacum arcticum the period is shorter than in T. officinale In general, under constant conditions the circadian oscillations of arctic plants persist for a shorter period than those of other plants. 3. The free running periods of several of the investigated species from tropical regions are much longer than 24 hours, i.e., much longer than those of species from Central-European and arctic regions. 4. The free running periods of several tropical species are temperature-independent (Erythrina senegalensis, Albizzia lophanta, Rhynchosia memmonia, Vigna catjang, Phaseolus multiflorus). In other tropical species, however, the periods decrease rather strongly with increasing temperature (Phaseolus mungo, Canavalia obtusifolia, Clitoria ternatea, Dolichos lablab, Vigna sesquipedalis, Dolichos zebra). The temperature does not influence the amplitudes in Phaseolus mungo and Vigna sesquipedalis, but it strongly influences the amplitudes in Erythrina senegalensis, in LD-cycles as well as in continuous light. 5. The arctic plant Astragalus frigidus still shows free running oscillations at 12°C, whereas several tropical species oscillate only at temperatures above 17°C. 6. The differences in the periods of tropical and non-tropical species (see under [3]) disappear if the plants are compared not at the same temperature but at temperatures which are optimal for them. If tropical plants are tested 27°C and Central-European and arctic species at 17°C, the periods always approach the value of 24 hours. PMID:24557984

Mayer, W

1966-09-01

311

Spectral sensitivity of photoreceptors mediating phase-shifts of circadian rhythms in retinally degenerate CBA\\/J ( rd\\/rd ) and normal CBA\\/N (+\\/+) mice  

Microsoft Academic Search

Light-dark cycles are the most important time cue for the circadian system to entrain the endogenous circadian clock to the environmental 24 h cycle. Although photic entrainment of circadian rhythms is mediated by the eye in mammals, photoreceptors implicated in circadian photoreception remain unknown. In our previous study, retinally degenerate CBA\\/J (rd\\/rd) mice were found to have lower circadian photo-sensitivity

T. Yoshimura; S. Ebihara

1996-01-01

312

Effects of square-wave and simulated natural light-dark cycles on hamster circadian rhythms  

NASA Technical Reports Server (NTRS)

Circadian rhythms of activity (Act) and body temperature (Tb) were recorded from male Syrian hamsters under square-wave (LDSq) and simulated natural (LDSN, with dawn and dusk transitions) light-dark cycles. Light intensity and data sampling were under the synchronized control of a laboratory computer. Changes in reactive and predictive onsets and offsets for the circadian rhythms of Act and Tb were examined in both lighting conditions. The reactive Act onset occurred 1.1 h earlier (P < 0.01) in LDSN than in LDSq and had a longer alpha-period (1.7 h; P < 0.05). The reactive Tb onset was 0.7 h earlier (P < 0.01) in LDSN. In LDSN, the predictive Act onset advanced by 0.3 h (P < 0.05), whereas the Tb predictive onset remained the same as in LDSq. The phase angle difference between Act and Tb predictive onsets decreased by 0.9 h (P < 0.05) in LDSN, but the offsets of both measures remained unchanged. In this study, animals exhibited different circadian entrainment characteristics under LDSq and LDSN, suggesting that gradual and abrupt transitions between light and dark may provide different temporal cues.

Tang, I. H.; Murakami, D. M.; Fuller, C. A.

1999-01-01

313

High-salt diet advances molecular circadian rhythms in mouse peripheral tissues.  

PubMed

Dietary compounds influence the expression of various genes and play a major role in changing physiological and metabolic states. However, little is known about the role of food ingredients in the regulation of circadian gene expression. Here, we show that feeding mice with a high-salt (HS) diet ad libitum for over 2weeks advanced the phase of clock gene expression by about 3h in the liver, kidney, and lung, but did not change circadian feeding, drinking, and locomotor rhythms. Focused DNA microarray analysis showed that the expression phase of many genes related to metabolism in the liver was also advanced. Immediately before phase advancement in peripheral tissues, the mRNA expression of sodium-glucose cotransporter 1 (Sglt1) and glucose transporter 2 (Glut2), that are responsible for glucose absorption, was increased in the jejunum. Furthermore, blood glucose uptake increased more rapidly after consuming the HS diet than the control diet. Moreover, phloridzin, a specific inhibitor of SGLT1, prevented the increased glucose transporter expression in the jejunum and phase advancement in the livers of mice on the HS diet. These results suggest that increased glucose absorption induced by dietary HS alters the food entrainment of peripheral molecular circadian rhythms. PMID:20888322

Oike, Hideaki; Nagai, Kanji; Fukushima, Tatsunobu; Ishida, Norio; Kobori, Masuko

2010-11-01

314

Improvement of circadian rhythm of heart rate variability by eurythmy therapy training.  

PubMed

Background. Impairment of circadian rhythm is associated with various clinical problems. It not only has a negative impact on quality of life but can also be associated with a significantly poorer prognosis. Eurythmy therapy (EYT) is an anthroposophic movement therapy aimed at reducing fatigue symptoms and stress levels. Objective. This analysis of healthy subjects was conducted to examine whether the improvement in fatigue symptoms was accompanied by improvements in the circadian rhythm of heart rate variability (HRV). Design. Twenty-three women performed 10 hours of EYT over six weeks. Electrocardiograms (ECGs) were recorded before and after the EYT trial. HRV was quantified by parameters of the frequency and time domains and the nonlinear parameters of symbolic dynamics. Results. The day-night contrast with predominance of vagal activity at night becomes more pronounced after the EYT training, and with decreased Ultralow and very low frequencies, the HRV shows evidence of calmer sleep. During the night, the complexity of the HRV is significantly increased indicated by nonlinear parameters. Conclusion. The analysis of the circadian patterns of cardiophysiological parameters before and after EYT shows significant improvements in HRV in terms of greater day-night contrast caused by an increase of vagal activity and calmer and more complex HRV patterns during sleep. PMID:23533496

Seifert, Georg; Kanitz, Jenny-Lena; Pretzer, Kim; Henze, Günter; Witt, Katharina; Reulecke, Sina; Voss, Andreas

2013-01-01

315

Improvement of Circadian Rhythm of Heart Rate Variability by Eurythmy Therapy Training  

PubMed Central

Background. Impairment of circadian rhythm is associated with various clinical problems. It not only has a negative impact on quality of life but can also be associated with a significantly poorer prognosis. Eurythmy therapy (EYT) is an anthroposophic movement therapy aimed at reducing fatigue symptoms and stress levels. Objective. This analysis of healthy subjects was conducted to examine whether the improvement in fatigue symptoms was accompanied by improvements in the circadian rhythm of heart rate variability (HRV). Design. Twenty-three women performed 10 hours of EYT over six weeks. Electrocardiograms (ECGs) were recorded before and after the EYT trial. HRV was quantified by parameters of the frequency and time domains and the nonlinear parameters of symbolic dynamics. Results. The day-night contrast with predominance of vagal activity at night becomes more pronounced after the EYT training, and with decreased Ultralow and very low frequencies, the HRV shows evidence of calmer sleep. During the night, the complexity of the HRV is significantly increased indicated by nonlinear parameters. Conclusion. The analysis of the circadian patterns of cardiophysiological parameters before and after EYT shows significant improvements in HRV in terms of greater day-night contrast caused by an increase of vagal activity and calmer and more complex HRV patterns during sleep.

Seifert, Georg; Kanitz, Jenny-Lena; Pretzer, Kim; Henze, Gunter; Witt, Katharina; Reulecke, Sina; Voss, Andreas

2013-01-01

316

The parathyroid hormone circadian rhythm is truly endogenous--a general clinical research center study  

NASA Technical Reports Server (NTRS)

While circulating levels of PTH follow a diurnal pattern, it has been unclear whether these changes are truly endogenous or are dictated by external factors that themselves follow a diurnal pattern, such as sleep-wake cycles, light-dark cycles, meals, or posture. We evaluated the diurnal rhythm of PTH in 11 normal healthy male volunteers in our Intensive Physiologic Monitoring Unit. The first 36 h spent under baseline conditions were followed by 28-40 h of constant routine conditions (CR; enforced wakefulness in the strict semirecumbent position, with the consumption of hourly snacks). During baseline conditions, PTH levels followed a bimodal diurnal rhythm with an average amplitude of 4.2 pg/mL. A primary peak (t1max) occurred at 0314 h, and the secondary peak (t2max) occurred at 1726 h, whereas the primary and secondary nadirs (t1min and t2min) took place, on the average, at 1041 and 2103 h, respectively. This rhythm was preserved under CR conditions, albeit with different characteristics, thus confirming its endogenous nature. The serum ionized calcium (Cai) demonstrated a rhythm in 3 of the 5 subjects studied that varied widely between individuals and did not have any apparent relation to PTH. Urinary calcium/creatinine (UCa/Cr), phosphate/Cr (UPO4/Cr), and sodium/Cr (UNa/Cr) ratios all followed a diurnal rhythm during the baseline day. These rhythms persisted during the CR, although with different characteristics for the first two parameters, whereas that of UNa/Cr was unchanged. In general, the temporal pattern for the UCa/Cr curve was a mirror image of the PTH curve, whereas the UPO4/Cr pattern moved in parallel with the PTH curve. In conclusion, PTH levels exhibit a diurnal rhythm that persists during a CR, thereby confirming that a large component of this rhythm is an endogenous circadian rhythm. The clinical relevance of this rhythm is reflected in the associated rhythms of biological markers of PTH effect at the kidney, namely UCa/Cr and UPO4/Cr.

el-Hajj Fuleihan, G.; Klerman, E. B.; Brown, E. N.; Choe, Y.; Brown, E. M.; Czeisler, C. A.

1997-01-01

317

The Scorpion An ideal animal model to study long-term microgravity effects on circadian rhythms  

NASA Astrophysics Data System (ADS)

The temporal pattern of light and darkness is basic for the coordination of circadian rhythms and establishment of homoeostasis. The 24th frequency of zeitgebers is probably a function of the Earth's rotation. The only way to eliminate its influence on organisms is to study their behavior in space because the reduced day length during orbiting the Earth might disrupt synchronizing mechanisms based on the 24th rhythm. The stability of microgravity induced disturbances of synchronization as well as the extent of adaptation of different physiological processes to this novel environment can only be studied during long-term exposures to microgravity, i.e., on the International Space Station. Biological studies within the long-term domain on ISS demand the use of experimental models which can be exposed to automatic handling of measurements and which need less or no nutritional care. Scorpions offer these features. We describe a fully automatic recording device for the simultaneous collection of data regarding the sensorimotor system and homoeostatic mechanisms. In particular, we record sensitivity changes of the eyes, motor activity and heart beat and/or respiratory activity. The advantage of the scorpion model is supported by the fact that data can be recorded preflight, inflight and postflight from the same animal. With this animal model, basic insights will be obtained about the de-coupling of circadian rhythms of multiple oscillators and their adaptation to the entraining zeitgeber periodicity during exposure to microgravity for at least three biological parameters recorded simultaneously. .

Riewe, Pascal C.; Horn, Eberhard R.

2000-01-01

318

Age-Related Changes in Both Circadian and Seasonal Rhythms of Rectal Temperature with Special Reference to Senile Dementia of Alzheimer Type  

Microsoft Academic Search

The biological rhythms of rectal temperature were documented in young (circadian variations) and elderly (circadian and seasonal variations) human subjects either in apparent good health or suffering from senile dementia of Alzheimer type (SDAT). All the subjects were synchronized. Data obtained showed a decrease of the body core temperature rhythm amplitude in the healthy elderly for each documented season but

Y. Touitou; A. Reinberg; A. Bogdan; A. Auzéby; H. Beck; C. Touitou

1986-01-01

319

Does disruption of circadian rhythms contribute to beta-cell failure in type 2 diabetes?  

PubMed

Type 2 diabetes mellitus (T2DM) is a complex metabolic disease characterized by the loss of beta-cell secretory function and mass. The pathophysiology of beta-cell failure in T2DM involves a complex interaction between genetic susceptibilities and environmental risk factors. One environmental condition that is gaining greater appreciation as a risk factor for T2DM is the disruption of circadian rhythms (eg, shift-work and sleep loss). In recent years, circadian disruption has become increasingly prevalent in modern societies and consistently shown to augment T2DM susceptibility (partly mediated through its effects on pancreatic beta-cells). Since beta-cell failure is essential for development of T2DM, we will review current work from epidemiologic, clinical, and animal studies designed to gain insights into the molecular and physiological mechanisms underlying the predisposition to beta-cell failure associated with circadian disruption. Elucidating the role of circadian clocks in regulating beta-cell health will add to our understanding of T2DM pathophysiology and may contribute to the development of novel therapeutic and preventative approaches. PMID:24532160

Rakshit, Kuntol; Thomas, Anthony P; Matveyenko, Aleksey V

2014-04-01

320

Influences of horizontal hypokinesia on performance and circadian physiological rhythms in female humans  

NASA Technical Reports Server (NTRS)

Eight females from 35-45 yr of age were subjected to seven days of ambulatory control, seven days of bed rest, and a five day recovery period, with 30 min of centrifugation on day seven of bedrest to determine the effects of weightlessness on the circadian rhythms of females in that age group. Heart rate and rectal temperature (RT) were monitored and each subject was tested in a flight simulator twice a day in conditions of varying levels of turbulence. The flight simulations were run during the morning and acrophase of the circadian RT and performance errors wery monitored for 6 min. No significant differences were detected in the group performance data pre-, during, and post-bedrest, although better performance in the simulator was observed after the centrifuge exposure. An RT phase shift was statistically significant between pre- and during bedrest stages.

Winget, C. M.; Deroshia, C. W.; Sandler, H.

1982-01-01

321

Circadian rhythms and metabolic syndrome: from experimental genetics to human disease  

PubMed Central

The incidence of the metabolic syndrome represents a spectrum of disorders that continue to increase across the industrialized world. Both genetic and environmental factors contribute to metabolic syndrome and recent evidence has emerged to suggest that alterations in circadian systems and sleep participate in the pathogenesis of the disease. In this review, we highlight studies at the intersection of clinical medicine and experimental genetics that pinpoint how perturbations of the internal clock system, and sleep, constitute risk factors for disorders including obesity, diabetes mellitus, cardiovascular disease, thrombosis and even inflammation. An exciting aspect of the field has been the integration of behavioural and physiological approaches, and the emerging insight into both neural and peripheral tissues in disease pathogenesis. Consideration of the cell and molecular links between disorders of circadian rhythms and sleep with metabolic syndrome has begun to open new opportunities for mechanism-based therapeutics.

Maury, Eleonore; Ramsey, Kathryn Moynihan; Bass, Joseph

2009-01-01

322

Primate circadian rhythms during spaceflight: results from Cosmos 2044 and 2229.  

PubMed

The circadian timing system (CTS) coordinates an animal's physiology and behavior both internally and with the 24-h day. Previous studies have suggested that the CTS is sensitive to changes in gravity. To examine this question, the expression of the CTS in four juvenile male rhesus macaques (Macaca mulatta) were studied in space. These animals were flown on the Cosmos 2044 and 2229 missions. Activity, heart rate, and axillary and brain (Cosmos 2229) temperatures were recorded. In both flights, the subjects exhibited delays in the phasing of their temperature rhythms and a decrease in mean heart rate compared with ground control studies. These data are in support of other studies that demonstrate that the CTS is sensitive to changes in the gravitational environment. Furthermore, the data also support the concept of a multioscillator organization of the primate CTS due to the differential responses of the rhythms measured. PMID:8828664

Fuller, C A; Hoban-Higgins, T M; Klimovitsky, V Y; Griffin, D W; Alpatov, A M

1996-07-01

323

Maximum entropy spectral analysis for circadian rhythms: theory, history and practice  

PubMed Central

There is an array of numerical techniques available to estimate the period of circadian and other biological rhythms. Criteria for choosing a method include accuracy of period measurement, resolution of signal embedded in noise or of multiple periodicities, and sensitivity to the presence of weak rhythms and robustness in the presence of stochastic noise. Maximum Entropy Spectral Analysis (MESA) has proven itself excellent in all regards. The MESA algorithm fits an autoregressive model to the data and extracts the spectrum from its coefficients. Entropy in this context refers to “ignorance” of the data and since this is formally maximized, no unwarranted assumptions are made. Computationally, the coefficients are calculated efficiently by solution of the Yule-Walker equations in an iterative algorithm. MESA is compared here to other common techniques. It is normal to remove high frequency noise from time series using digital filters before analysis. The Butterworth filter is demonstrated here and a danger inherent in multiple filtering passes is discussed.

2013-01-01

324

Effects of bilateral suprachiasmatic nucleus lesions on the circadian rhythms in a diurnal rodent, the Siberian chipmunk ( Eutamias sibiricus )  

Microsoft Academic Search

Effects of bilateral SCN lesions on the circadian rhythms of wheel-running activity and sleep-waking were examined in a diurnal rodent, the Siberian chipmunk,Eutamias sibiricus. The following results suggest that the SCN is a circadian pacemaker in the Siberian chipmunk:1.Retinohypothalamic projection was established in the chipmunk using HRP as an anterograde tracer (Fig. 1). The projection was bilateral and greater to

Tetsu Sato; Hiroshi Kawamura

1984-01-01

325

Circadian rhythms for calcium, inorganic phosphorus, and parathyroid hormone in primary hyperparathyroidism: functional and practical considerations.  

PubMed

We obtained serial serum and urine samples from 14 patients with primary hyperparathyroidism both before and 3 to 9 months after excision of their parathyroid adenomas to (1) determine whether the circadian rhythms for calcium, phosphorus, and parathyroid hormone (PTH) previously described in normal human beings are disturbed in this disorder; (2) gauge the effect of surgical treatment on the patterns observed before intervention; and (3) ascertain whether time(s) of blood sampling can be defined for optimal biochemical detection of the disease. Significant rhythms for serum phosphorus, ionized calcium, PTH, urine phosphorus, and urine calcium were observed in many but not all patients before and after surgery. Nonetheless, collective analysis revealed the following: (1) diurnal patterns for serum ionized calcium, phosphorus, urine calcium, and urine phosphorus in patients with primary hyperparathyroidism both before and after surgery, whereas a rhythm for serum PTH was uniquely observed after surgical treatment; and (2) no significant correlation between preoperative serum ionized calcium and PTH but restoration of the expected reciprocal relationship between these variables after surgery. Although variability in individual expression of the rhythm for PTH precludes precise definition of a sampling "window" when hormone levels are likely to be highest, collection of data at points throughout the day helped establish the diagnosis of primary hyperparathyroidism in several patients with borderline serum biochemistries. PMID:2588106

Lobaugh, B; Neelon, F A; Oyama, H; Buckley, N; Smith, S; Christy, M; Leight, G S

1989-12-01

326

Postnatal Constant Light Compensates Cryptochrome1 and 2 Double Deficiency for Disruption of Circadian Behavioral Rhythms in Mice under Constant Dark  

PubMed Central

Clock genes Cryptochrome (Cry1) and Cry2 are essential for expression of circadian rhythms in mice under constant darkness (DD). However, circadian rhythms in clock gene Per1 expression or clock protein PER2 are detected in the cultured suprachiasmatic nucleus (SCN) of neonatal Cry1 and Cry2 double deficient (Cry1-/-/Cry2-/-) mice. A lack of circadian rhythms in adult Cry1-/-/Cry2-/- mice is most likely due to developmentally disorganized cellular coupling of oscillating neurons in the SCN. On the other hand, neonatal rats exposed to constant light (LL) developed a tenable circadian system under prolonged LL which was known to fragment circadian behavioral rhythms. In the present study, Cry1-/-/Cry2-/- mice were raised under LL from postnatal day 1 for 7 weeks and subsequently exposed to DD for 3 weeks. Spontaneous movement was monitored continuously after weaning and PER2::LUC was measured in the cultured SCN obtained from mice under prolonged DD. Surprisingly, Chi square periodogram analysis revealed significant circadian rhythms of spontaneous movement in the LL-raised Cry1-/-/Cry2-/- mice, but failed to detect the rhythms in Cry1-/-/Cry2-/- mice raised under light-dark cycles (LD). By contrast, prolonged LL in adulthood did not rescue the circadian behavioral rhythms in the LD raised Cry1-/-/Cry2-/- mice. Visual inspection disclosed two distinct activity components with different periods in behavioral rhythms of the LL-raised Cry1-/-/Cry2-/- mice under DD: one was shorter and the other was longer than 24 hours. The two components repeatedly merged and separated. The patterns resembled the split behavioral rhythms of wild type mice under prolonged LL. In addition, circadian rhythms in PER2::LUC were detected in some of the LL-raised Cry1-/-/Cry2-/- mice under DD. These results indicate that neonatal exposure to LL compensates the CRY double deficiency for the disruption of circadian behavioral rhythms under DD in adulthood.

Ono, Daisuke; Honma, Sato; Honma, Ken-ichi

2013-01-01

327

Circadian Rhythms of Sense and Antisense Transcription in Sugarcane, a Highly Polyploid Crop  

PubMed Central

Commercial sugarcane (Saccharum hybrid) is a highly polyploid and aneuploid grass that stores large amounts of sucrose in its stem. We have measured circadian rhythms of sense and antisense transcription in a commercial cultivar (RB855453) using a custom oligoarray with 14,521 probes that hybridize to sense transcripts (SS) and 7,380 probes that hybridize to antisense transcripts (AS).We estimated that 32% of SS probes and 22% AS probes were rhythmic. This is a higher proportion of rhythmic probes than the usually found in similar experiments in other plant species. Orthologs and inparalogs of Arabidopsis thaliana, sugarcane, rice, maize and sorghum were grouped in ortholog clusters. When ortholog clusters were used to compare probes among different datasets, sugarcane also showed a higher proportion of rhythmic elements than the other species. Thus, it is possible that a higher proportion of transcripts are regulated by the sugarcane circadian clock. Thirty-six percent of the identified AS/SS pairs had significant correlated time courses and 64% had uncorrelated expression patterns. The clustering of transcripts with similar function, the anticipation of daily environmental changes and the temporal compartmentation of metabolic processes were some properties identified in the circadian sugarcane transcriptome. During the day, there was a dominance of transcripts associated with photosynthesis and carbohydrate metabolism, including sucrose and starch synthesis. During the night, there was dominance of transcripts associated with genetic processing, such as histone regulation and RNA polymerase, ribosome and protein synthesis. Finally, the circadian clock also regulated hormone signalling pathways: a large proportion of auxin and ABA signalling components were regulated by the circadian clock in an unusual biphasic distribution.

Hotta, Carlos Takeshi; Nishiyama, Milton Yutaka; Souza, Glaucia Mendes

2013-01-01

328

Two-oscillator structure of the pacemaker controlling the circadian rhythm of N-acetyltransferase in the rat pineal gland  

Microsoft Academic Search

1.The organization of the pacemaker driving the circadian rhythm of N-acetyltransferase activity in the rat pineal gland was studied by observing changes of the rhythm caused by 1 min light pulses applied at night. These pulses proved to be effective phase-shifting signals.2.After 1 min light pulses applied in the first half of the night. N-acetyltransferase activity began to increase anew

Helena Illnerová; Ji?í Van??ek

1982-01-01

329

Properties of the Aplysia visual system: in vitro entrainment of the circadian rhythm and centrifugal regulation of the eye  

Microsoft Academic Search

1.Properties of the visual system of Aplysia californica were studied by recording optic nerve impulses extracellularly from isolated eyes in constant darkness.2.In vivo entrainment of the circadian rhythm of afferent optic nerve impulses by LD 12:12 cycles phase advanced 13 hours was essentially complete after only one exposure of the animal to this light cycle.3.The impulse rhythms of eyes exposed

Arnold Eskin

1971-01-01

330

Influence of losartan intake on the circadian rhythm of melatonin secretion in humans.  

PubMed

It has been reported that losartan, an angiotensin II receptor blocker, alters the circadian rhythm of melatonin secretion and significantly reduces melatonin production. However, this finding has been confirmed at the animal experiment level only, and there are no reports of studies in humans. Therefore, we performed this study to confirm the reproducibility of the aforementioned findings of animal experiments in humans. Ten male subjects who were in good general health and free from any medical condition were recruited for this study. After a preliminary observation period of 7 days, the subjects received oral losartan treatment, 50 mg daily for 7 days. Blood samplings for measurement of the plasma melatonin concentrations were performed on day 7 of the preliminary observation period and day 7 of the losartan treatment period. The circadian rhythm of melatonin secretion after the 7-day treatment with losartan showed no significant difference from that recorded before the losartan administration. The significant decrease of the home blood pressure was observed on the afternoons. The blood samples showed significant decrease of the serum sodium and uric acid levels, along with a significant increase of the serum potassium level. The pharmacological actions of losartan at the ordinarily used clinical dose level were confirmed in humans, however, no significant inhibitory effect of the drug on melatonin secretion could be confirmed. These results are expected to be useful for guiding the proper use of angiotensin II receptor blockers. PMID:24716408

Arakawa, M; Uchida, N; Kanda, N; Kurosawa, Y; Odani, T; Kanmatsuse, K; Endo, M; Yamazaki, T; Hidaka, S

2014-03-01

331

Linking the circadian rhythm gene arntl2 to interleukin 21 expression in type 1 diabetes.  

PubMed

The circadian rhythm-related aryl hydrocarbon receptor nuclear translocator-like 2 (Arntl2) gene has been identified as a candidate gene for the murine type 1 diabetes locus Idd6.3. Previous studies suggested a role in expansion of CD4(+)CD25(-) T cells, and this then creates an imbalance in the ratio between T-effector and CD4(+)CD25(+) T-regulator cells. Our transcriptome analyses identify the interleukin 21 (IL21) gene (Il21) as a direct target of ARNTL2. ARNTL2 binds in an allele-specific manner to the RNA polymerase binding site of the Il21 promoter and inhibits its expression in NOD.C3H congenic mice carrying C3H alleles at Idd6.3. IL21 is known to promote T-cell expansion, and in agreement with these findings, mice with C3H alleles at Idd6.3 produce lower numbers of CD4(+)IL21(+) and CD4(+) and CD8(+) T cells compared with mice with NOD alleles at Idd6.3. Our results describe a novel and rather unexpected role for Arntl2 in the immune system that lies outside of its predicted function in circadian rhythm regulation. PMID:24520124

Lebailly, Basile; He, Chenxia; Rogner, Ute C

2014-06-01

332

A novel multi-unit tablet for treating circadian rhythm diseases.  

PubMed

This study aimed to develop and evaluate a novel multi-unit tablet that combined a pellet with a sustained-release coating and a tablet with a pulsatile coating for the treatment of circadian rhythm diseases. The model drug, isosorbide-5-mononitrate, was sprayed on microcrystalline cellulose (MCC)-based pellets and coated with Eudragit(®) NE30D, which served as a sustained-release layer. The coated pellets were compressed with cushion agents (a mixture of MCC PH-200/ MCC KG-802/PC-10 at a ratio of 40:40:20) at a ratio of 4:6 using a single-punch tablet machine. An isolation layer of OpadryII, swellable layer of HPMC E5, and rupturable layer of Surelease(®) were applied using a conventional pan-coating process. Central-composite design-response surface methodology was used to investigate the influence of these coatings on the square of the difference between release times over a 4 h time period. Drug release studies were carried out on formulated pellets and tablets to investigate the release behaviors, and scanning electron microscopy (SEM) was used to monitor the pellets and tablets and their cross-sectional morphology. The experimental results indicated that this system had a pulsatile dissolution profile that included a lag period of 4 h and a sustained-release time of 4 h. Compared to currently marketed preparations, this tablet may provide better treatment options for circadian rhythm diseases. PMID:23649996

Liu, Qi; Gong, Yinhua; Shi, Yun; Jiang, Liqun; Zheng, Chunli; Ge, Liang; Liu, Jianping; Zhu, Jiabi

2013-06-01

333

Circadian rhythm drives the responsiveness of leptin-mediated hypothalamic pathway of cholecystokinin-8.  

PubMed

Cholecystokinin (CCK) and leptin act coordinately in the brain to regulate food intake and energy balance. Recently we have reported that CCK enhances the permeability of brain barriers to leptin and we have proposed that CCK enhances energy expenditure in rats by activating in the hypothalamus the janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway, which is coupled to leptin receptors. Because plasma leptin concentration follows a circadian rhythm (plasma leptin concentration rise maximal values during the night, after rats start eating), we have hypothesized that the interaction between leptin and CCK should be more intense in animals receiving CCK during the night, i.e., during periods of positive energy balance. In order to further characterize the physiological relevance of the interplay between leptin and CCK we have compared the effect of diurnal vs. nocturnal administration of the C-terminal octapeptide of CCK (CCK-8) on (i) body weight and food intake, and (ii) STAT3 activation, by analyzing phosphorylated STAT3 (pSTAT3) immunostaining within the arcuate nucleus of the hypothalamus. Our results show that CCK decreases body weight and food intake only after p.m. administration. Accordingly pSTAT3 immunostaining within the hypothalamus was more intense in p.m. than in a.m.-treated animals. These data suggest that the effect of CCK on leptin pathways follows a circadian rhythm linked to the energy balance status and gives further support to the interaction between leptin and CCK. PMID:18638520

Merino, Beatriz; Somoza, Beatriz; Ruiz-Gayo, Mariano; Cano, Victoria

2008-09-12

334

Can Acupuncture Affect the Circadian Rhythm of Blood Pressure? A Randomized, Double-Blind, Controlled Trial  

PubMed Central

Abstract Objectives The objective of the study was to investigate the effect of acupuncture on the circadian rhythm of blood pressure (BP) in patients with hypertension. Design The study was designed as a randomized, double-blind, controlled trial. Subjects were randomly divided into an active acupuncture group and a sham acupuncture group. Each patient received real or sham acupuncture treatment twice a week for 8 weeks. Acupuncture needles were inserted at bilateral ST 36 plus PC 6; placebo points. Subjects Thirty-three (33) patients with essential hypertension were the subjects. Outcome measures Twenty-four (24)-hour ambulatory BP was assessed before and after treatment. Results After the treatment period, there was a significant increase in nocturnal diastolic BP dipping compared to that at baseline (10.20±7.56?mm Hg versus 5.21±10.19?mm Hg, p=0.038) in the active acupuncture group but not in the sham acupuncture group. The nocturnal diastolic BP dipping response to active acupuncture treatment was significantly different from the response seen with the sham acupuncture treatment (p=0.041). The number of dippers also increased from 4 to 8 in the active acupuncture group. Average systolic and diastolic BP was not changed significantly except for nighttime diastolic BP (90.32±11.47?mm Hg to 87.83±9.16?mm Hg, p=0.041). Conclusions It is suggested that acupuncture treatment could be useful for improving the circadian rhythm of BP in patients with hypertension.

Kim, Hye-Mi; Cho, Seung-Yeon; Sohn, Il-Suk; Jung, Woo-Sang; Moon, Sang-Kwan; Park, Jung-Mi; Ko, Chang-Nam; Cho, Ki-Ho

2012-01-01

335

Cellular Analysis of Circadian Rhythmicity in Cultured SCN Neurons.  

National Technical Information Service (NTIS)

Circadian rhythms are generated by brain cells located in the suprachiasmatic nuclei (SCN) of the mammalian hypothalamus, but it is not clear how individual cells contribute to the operation of the circadian clock. SCN neurons dissociated from newborn rat...

S. M. Reppert D. K. Welsh

1994-01-01

336

Tonic Neuromodulation of the Inspiratory Rhythm Generator  

PubMed Central

The generation of neural network dynamics relies on the interactions between the intrinsic and synaptic properties of their neural components. Moreover, neuromodulators allow networks to change these properties and adjust their activity to specific challenges. Endogenous continuous (“tonic”) neuromodulation can regulate and sometimes be indispensible for networks to produce basal activity. This seems to be the case for the inspiratory rhythm generator located in the pre-Bötzinger complex (preBötC). This neural network is necessary and sufficient for generating inspiratory rhythms. The preBötC produces normal respiratory activity (eupnea) as well as sighs under normoxic conditions, and it generates gasping under hypoxic conditions after a reconfiguration process. The reconfiguration leading to gasping generation involves changes of synaptic and intrinsic properties that can be mediated by several neuromodulators. Over the past years, it has been shown that endogenous continuous neuromodulation of the preBötC may involve the continuous action of amines and peptides on extrasynaptic receptors. I will summarize the findings supporting the role of endogenous continuous neuromodulation in the generation and regulation of different inspiratory rhythms, exploring the possibility that these neuromodulatory actions involve extrasynaptic receptors along with evidence of glial modulation of preBötC activity.

Pena-Ortega, Fernando

2012-01-01

337

Reproducibility of the circadian rhythms of serum cortisol and melatonin in healthy subjects: a study of three different 24-h cycles over six weeks  

Microsoft Academic Search

Plasma melatonin and cortisol are characterized by a marked circadian rhythm, but little information is available about the reproducibility and stability of these rhythms over several weeks in the same subjects. This study examined the characteristics of these rhythms in 31 healthy human subjects 20 to 30 years of age. They were synchronized with a diurnal activity from 0800 to

Brahim Selmaoui; Yvan Touitou

2003-01-01

338

Light-sampling behavior in photoentrainment of a rodent circadian rhythm.  

PubMed

Behavioral aspects of photoentrainment of circadian locomotor activity rhythms were recorded for a nocturnal den-dwelling rodent, the flying squirrel, Glaucomys volans. Methods included both telemetric monitoring and infrared observations of animals under constant dark (DD) or light-dark (LD) schedules in either standard wheel cages or in newly developed simulated den cages. By means of the den cages, several aspects of a circadian activity cycle could be simultaneously measured emphasizing the arousal from rest, the light-sampling behavior by which a squirrel assessed the environmental photoregimen, and the phase-shifting by which photoentrainment was achieved. Each animal in a den cage remained for 12 or more hours of its rest period almost exclusively in the darkened nest box, then at an abrupt arousal time moved to the light-sampling porthole. In darkness each animal initiated wheel activity immediately after arousal; light at arousal time, however, induced a return to the nest box for a nap and a delay phase-shift in onset of activity of approximately 40 min. On subsequent days, each animal appeared to be free-running (tau FR less than 24 h) until onset again advanced into the light period. A squirrel usually viewed only a few minutes light per day, and on free-running days occasionally saw none of the 12-h light period. The significance of these data for theories of circadian photoentrainment is discussed. PMID:3761222

DeCoursey, P J

1986-08-01

339

Sleep and circadian rhythms of an airline pilot operating on the polar route: a case study.  

PubMed

This study was planned and performed as a first step to assess sleep behaviour and circadian rhythmicity in aircrews operating on regular passenger flights between Germany and Japan via Anchorage, AK. Sleep patterns as well as continuous recordings of ECG and temperature were obtained from a B747 captain during a period of 13 d, including a preceding control day, 8 d on duty and 4 d at home base after return. Sleep behaviour and circadian rhythms changed dramatically due to adverse effects from the duty roster on the polar route. Sleep periods became fragmented into several sleep periods per day in a very irregular manner. Total sleep duration was shortened and sleep deficits occurred between flights. After return to the home base, sleep distribution remained divided into two intervals per day. The circadian system was considerably disrupted on route. Effects associated with irregular duty and sleep patterns intensified desynchronization. Readjustment was extremely slow resulting in a phase-displacement of at least 10 h even after being home for 4 d. Altogether, the results give reason for serious concerns and for the conclusion to strongly recommend more extensive studies on this route. PMID:3390101

Samel, A; Wegmann, H M

1988-05-01

340

Habitual moderate alcohol consumption desynchronizes circadian physiologic rhythms and affects reaction-time performance.  

PubMed

The authors studied longitudinally four healthy young adults to explore if habitual evening intake of a "moderate" amount of wine alters parameters, including period (?) of circadian rhythms. Subjects, synchronized by diurnal activity from 07.30?h?±?60?min to 23.00?h?±?90?min and nocturnal rest, were studied during a continuous 22-day span: 11 days without alcohol (control) and 11 days with a glass (200?mL) of wine nightly at supper (alcohol). The amount of alcohol ingested with dinner ranged from 0.28 to 0.42?g/kg/24?h/participant and the estimated evening blood alcohol level ranged from 0.02 to 0.10?g/L/participant. Single reaction time (SRT; yellow light signal), three-choice reaction time (CRT) (red, green, and yellow signals) of both hands, related cumulated errors (c-errors), as well as oral temperature (OT) and grip strength (GS) were measured four to seven times/24?h. Time series were analyzed individually to quantify 24-h means (M), circadian ? (power spectra), and cosinor, and correlation, ?(2), and t tests were performed. The sleep-wake ? (actography) was 24?h in every subject for both conditions. With alcohol, all subjects showed an OT circadian ? shorter than the control one. The SRT circadian M was longer (poorer performance) with wine versus control in three subjects, while CRT was longer with wine versus control in only one subject. Correlation analyses also showed the detrimental effect of alcohol on the same variables. Number of days with <2 c-errors was predominant in control and decreased with alcohol, especially for SRT. The desynchronization of the 10 different documented rhythms was greater with alcohol with reference to control in two of the four studied subjects. This work shows that habitual "moderate" wine drinking at supper reduces the performance of subjects, increases the level of c-errors/24?h, especially for SRT, suggesting a "moderate" amount of alcohol has the potential to increase accident risk, and it can also desynchronize circadian time organization. PMID:20969532

Reinberg, Alain; Touitou, Yvan; Lewy, Hadas; Mechkouri, Mohamed

2010-10-01

341

Circadian Rhythm in Heat Production of Limit-Fed Growing Pigs of Several Breeds Kept at and Below Thermal Neutrality  

Microsoft Academic Search

Circadian rhythm in total and ac- tivity-free heat production ( H and Hacf, respectively) was studied in Norwegian Landrace (N), Finnish Landrace (F), Dutch Landrace (D), and Great Yorkshire (Y) barrows. Animals, weighing 26 kg at the start of the study, were kept in groups for 18 2-d periods in climate respiration chambers at en- vironmental temperatures (T env) between

A. M. Henken; H. A. Brandsma; W. van der Hel; M. W. A. Verstegen

2010-01-01

342

The circadian rhythm of carbon-dioxide metabolism in Bryophyllum: the mechanism of phase-shift induction by thermal stimuli  

Microsoft Academic Search

The detailed characteristics have been established for the phase shifts induced by high-temperature (35° C) stimuli in the circadian rhythm of phosphoenolpyruvate-carboxylase activity in leaves of Bryophyllum fedtschenkoi otherwise kept under constant environmental conditions. The magnitude and direction of the shifts depend upon the duration of the stimulus and its position in the cycle, and are closely similar to those

Malcolm B. Wilkins

1983-01-01

343

Circadian rhythm affects the preventive role of pulsed electromagnetic fields on ovariectomy-induced osteoporosis in rats  

Microsoft Academic Search

Pulsed electromagnetic fields (PEMF) have been proved effective in the prevention of osteoporosis both experimentally and clinically. Chronotherapy studies have shown that circadian rhythm (CR) played an important role in the occurrence, development and treatment of several diseases. CR has also been recognized as an essential feature of bone metabolism. Therefore, it is of therapeutic significance to investigate the impact

Da Jing; Guanghao Shen; Jinghui Huang; Kangning Xie; Jing Cai; Qiaoling Xu; Xiaoming Wu; Erping Luo

2010-01-01

344

Temperature Circadian Rhythms during the Menstrual Cycle and Sleep Deprivation in Premenstrual Dysphoric Disorder and Normal Comparison Subjects  

Microsoft Academic Search

The aim of this study was to test the hypothesis that the circadian rhythm of core body temperature is altered in premenstrual dysphoric disorder (PMDD) subjects compared to that in normal comparison (NC) subjects and that it is normalized in PMDD subjects after treatment with early night partial sleep deprivation (ESD) or late night partial sleep deprivation (LSD). A total

Barbara L. Parry; Betina LeVeau; Nasim Mostofi; Richard Loving; Paul Clopton; J. Christian Gillin

1997-01-01

345

Chronotype differences in circadian rhythms of temperature, melatonin, and sleepiness as measured in a modified constant routine protocol.  

PubMed

Evening chronotypes typically have sleep patterns timed 2-3 hours later than morning chronotypes. Ambulatory studies have suggested that differences in the timing of underlying circadian rhythms as a cause of the sleep period differences. However, differences in endogenous circadian rhythms are best explored in laboratory protocols such as the constant routine. We used a 27-hour modified constant routine to measure the endogenous core temperature and melatonin circadian rhythms as well as subjective and objective sleepiness from hourly 15-minute sleep opportunities. Ten (8f) morning type individuals were compared with 12 (8f) evening types. All were young, healthy, good sleepers. The typical sleep onset, arising times, circadian phase markers for temperature and melatonin and objective sleepiness were all 2-3 hours later for the evening types than morning types. However, consistent with past studies the differences for the subjective sleepiness rhythms were much greater (5-9 hours). Therefore, the present study supports the important role of subjective alertness/sleepiness in determining the sleep period differences between morning and evening types and the possible vulnerability of evening types to delayed sleep phase disorder. PMID:23616692

Lack, Leon; Bailey, Michelle; Lovato, Nicole; Wright, Helen

2009-01-01

346

PDP1? functions downstream of the circadian oscillator to mediate behavioral rhythms Abbreviated title: PDP1? function in the circadian clock  

PubMed Central

The Drosophila circadian oscillator is comprised of autoregulatory period/timeless (per/tim) and Clock (Clk) feedback loops that control rhythmic transcription. In the Clk loop, CLOCK-CYCLE (CLK-CYC) heterodimers activate vrille (vri) and PAR domain protein 1? (Pdp1?) transcription, then sequential repression by VRI and activation by PDP1? mediate rhythms in Clk transcription. Since VRI and PDP1? bind the same regulatory element, the VRI/PDP1? ratio is thought to control the level of Clk transcription. Thus, constant high or low PDP1? levels in clock cells should eliminate Clk mRNA cycling and disrupt circadian oscillator function. Here we show that reducing PDP1? levels in clock cells by ~70% via RNA interference or increasing PDP1? levels by ~10-fold in clock cells does not alter Clk mRNA cycling or circadian oscillator function. However, constant low or high PDP1? levels in clock cells disrupt locomotor activity rhythms despite persistent circadian oscillator function in brain pacemaker neurons that extend morphologically normal projections into the dorsal brain. These results demonstrate that the VRI/PDP1? ratio neither controls Clk mRNA cycling nor circadian oscillator function, and argue that PDP1? is not essential for Clk activation. PDP1? is nevertheless required for behavioral rhythmicity, which suggests that it functions to regulate oscillator output.

Benito, Juliana; Zheng, Hao; Hardin, Paul E.

2007-01-01

347

Adjustment of sleep and the circadian temperature rhythm after flights across nine time zones  

NASA Technical Reports Server (NTRS)

The adjustment of sleep-wake patterns and the circadian temperature rhythm was monitored in nine Royal Norwegian Airforce volunteers operating P-3 aircraft during a westward training deployment across nine time zones. Subjects recorded all sleep and nap times, rated nightly sleep quality, and completed personality inventories. Rectal temperature, heart rate, and wrist activity were continuously monitored. Adjustment was slower after the return eastward flight than after the outbound westward flight. The eastward flight produced slower readjustment of sleep timing to local time and greater interindividual variability in the patterns of adjustment of sleep and temperature. One subject apparently exhibited resynchronization by partition, with the temperature rhythm undergoing the reciprocal 15-h delay. In contrast, average heart rates during sleep were significantly elevated only after westward flight. Interindividual differences in adjustment of the temperature rhythm were correlated with some of the personality measures. Larger phase delays in the overall temperature waveform (as measured on the 5th day after westward flight) were exhibited by extraverts, and less consistently by evening types.

Gander, Philippa H.; Myhre, Grete; Graeber, R. Curtis; Lauber, John K.; Andersen, Harald T.

1989-01-01

348

Influence of sleep-wake and circadian rhythm disturbances in psychiatric disorders  

PubMed Central

Recent evidence shows that the temporal alignment between the sleep-wake cycle and the circadian pacemaker affects self-assessment of mood in healthy subjects. Despite the differences in affective state between healthy subjects and patients with psychiatric disorders, these results have implications for analyzing diurnal variation of mood in unipolar and bipolar affective disorders and sleep disturbances in other major psychiatric conditions such as chronic schizophrenia. In a good proportion of patients with depression, mood often improves over the course of the day; an extension of waking often has an antidepressant effect. Sleep deprivation has been described as a treatment for depression for more than 30 years, and approximately 50% to 60% of patients with depression respond to this approach, especially those patients who report that their mood improves over the course of the day. The mechanisms by which sleep deprivation exerts its antidepressant effects are still controversial, but a reduction in rapid eye movement sleep (REM sleep), sleep pressure and slow-wave sleep (SWS), or a circadian phase disturbance, have been proposed. Although several studies support each of these hypotheses, none is sufficient to explain all observations reported to date. Unfortunately, the disturbed sleep-wake cycle or behavioural activities of depressed patients often explain several of the abnormalities reported in the diurnal rhythms of these patients. Thus, protocols that specifically manipulate the sleep-wake cycle to unmask the expression of the endogenous circadian pacemaker are greatly needed. In chronic schizophrenia, significant disturbances in sleep continuity, REM sleep, and SWS have been consistently reported. These disturbances are different from those observed in depression, especially with regard to REM sleep. Circadian phase abnormalities in schizophrenic patients have also been reported. Future research is expected to clarify the nature of these abnormalities. Images Fig. 1

Boivin, DB

2000-01-01

349

Extensive and divergent circadian gene expression in liver and heart  

Microsoft Academic Search

Many mammalian peripheral tissues have circadian clocks; endogenous oscillators that generate transcriptional rhythms thought to be important for the daily timing of physiological processes. The extent of circadian gene regulation in peripheral tissues is unclear, and to what degree circadian regulation in different tissues involves common or specialized pathways is unknown. Here we report a comparative analysis of circadian gene

Kai-Florian Storch; Ovidiu Lipan; Igor Leykin; N. Viswanathan; Fred C. Davis; Wing H. Wong; Charles J. Weitz

2002-01-01

350

Effects of Exposure to Intermittent versus Continuous Red Light on Human Circadian Rhythms, Melatonin Suppression, and Pupillary Constriction  

PubMed Central

Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n?=?24, 21–28 yr) lived individually in a laboratory for 6 consecutive days. Circadian rhythms of melatonin, cortisol, body temperature, and heart rate were assessed before and after exposure to 6 h of continuous red light (631 nm, 13 log photons cm?2 s?1), intermittent red light (1 min on/off), or bright white light (2,500 lux) near the onset of nocturnal melatonin secretion (n?=?8 in each group). Melatonin suppression and pupillary constriction were also assessed during light exposure. We found that circadian resetting responses were similar for exposure to continuous versus intermittent red light (P?=?0.69), with an average phase delay shift of almost an hour. Surprisingly, 2 subjects who were exposed to red light exhibited circadian responses similar in magnitude to those who were exposed to bright white light. Red light also elicited prolonged pupillary constriction, but did not suppress melatonin levels. These findings suggest that, for red light stimuli outside the range of sensitivity for melanopsin, cone photoreceptors can mediate circadian phase resetting of physiologic rhythms in some individuals. Our results also show that sensitivity thresholds differ across non-visual light responses, suggesting that cones may contribute differentially to circadian resetting, melatonin suppression, and the pupillary light reflex during exposure to continuous light.

Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J.

2014-01-01

351

Hierarchy of models: from qualitative to quantitative analysis of circadian rhythms in cyanobacteria.  

PubMed

A hierarchy of models, ranging from high to lower levels of abstraction, is proposed to construct "minimal" but predictive and explanatory models of biological systems. Three hierarchical levels will be considered: Boolean networks, piecewise affine differential (PWA) equations, and a class of continuous, ordinary, differential equations' models derived from the PWA model. This hierarchy provides different levels of approximation of the biological system and, crucially, allows the use of theoretical tools to more exactly analyze and understand the mechanisms of the system. The Kai ABC oscillator, which is at the core of the cyanobacterial circadian rhythm, is analyzed as a case study, showing how several fundamental properties-order of oscillations, synchronization when mixing oscillating samples, structural robustness, and entrainment by external cues-can be obtained from basic mechanisms. PMID:23822511

Chaves, M; Preto, M

2013-06-01

352

Effects of Restricted Fructose Access on Body Weight and Blood Pressure Circadian Rhythms  

PubMed Central

High-fructose diet is known to produce cardiovascular and metabolic pathologies. The objective was to determine whether the timing of high fructose (10% liquid solution) intake affect the metabolic and cardiovascular outcomes. Male C57BL mice with radiotelemetric probes were divided into four groups: (1) 24?h water (control); (2) 24?h fructose (F24); (3) 12?h fructose during the light phase (F12L); (4) 12?h fructose during the dark phase (F12D). All fructose groups had higher fluid intake. Body weight was increased in mice on restricted access with no difference in total caloric intake. Fasting glycemia was higher in groups with restricted access. F24 mice showed a fructose-induced blood pressure increase during the dark period. Blood pressure circadian rhythms were absent in F12L mice. Results suggest that the timing of fructose intake is an important variable in the etiology of cardiovascular and metabolic pathologies produced by high fructose consumption.

Senador, Danielle; Shewale, Swapnil; Irigoyen, Maria Claudia; Elased, Khalid M.; Morris, Mariana

2012-01-01

353

Hierarchy of models: From qualitative to quantitative analysis of circadian rhythms in cyanobacteria  

NASA Astrophysics Data System (ADS)

A hierarchy of models, ranging from high to lower levels of abstraction, is proposed to construct ``minimal'' but predictive and explanatory models of biological systems. Three hierarchical levels will be considered: Boolean networks, piecewise affine differential (PWA) equations, and a class of continuous, ordinary, differential equations' models derived from the PWA model. This hierarchy provides different levels of approximation of the biological system and, crucially, allows the use of theoretical tools to more exactly analyze and understand the mechanisms of the system. The Kai ABC oscillator, which is at the core of the cyanobacterial circadian rhythm, is analyzed as a case study, showing how several fundamental properties--order of oscillations, synchronization when mixing oscillating samples, structural robustness, and entrainment by external cues--can be obtained from basic mechanisms.

Chaves, M.; Preto, M.

2013-06-01

354

Regularity of daily life in relation to personality, age, gender, sleep quality and circadian rhythms  

NASA Technical Reports Server (NTRS)

A diary-like instrument to measure lifestyle regularity (the 'Social Rhythm Metric'-SRM) was given to 96 subjects (48 women, 48 men), 39 of whom repeated the study after at least one year, with additional objective measures of rest/activity. Lifestyle regularity as measured by the SRM related to age, morningness, subjective sleep quality and time-of-day variations in alertness, but not to gender, extroversion or neuroticism. Statistically significant test-retest correlations of about 0.4 emerged for SRM scores over the 12-30 month delay. Diary-based estimates of bedtime and waketime appeared fairly reliable. In a further study of healthy young men, 4 high SRM scorers ('regular') had a deeper nocturnal body temperature trough than 5 low SRM scorers ('irregular'), suggesting a better functioning circadian system in the 'regular' group.

Monk, T. H.; Petrie, S. R.; Hayes, A. J.; Kupfer, D. J.

1994-01-01

355

Effect of bedrest on circadian rhythms of plasma renin, aldosterone, and cortisol  

NASA Technical Reports Server (NTRS)

Previous studies of normal men after 5 d of bedrest showed that circulatory instability on head-up tilt or standing is preceded by increased plasma renin activity (PRA) at bedrest. In the present study, the circadian rhythms of PRA, aldosterone, and cortisol have been observed in five normal men on a constant diet. In ambulatory controls, PRA and aldosterone increased normally after standing. On the third morning of bedrest, PRA was higher than before, and at noon, PRA was higher than in standing controls. The nocturnal peaks of PRA resulting from episodic renin secretion during sleep were higher after bedrest. Plasma aldosterone was also increased by bedrest. The findings are compatible with the theory that intermittent beta-adrenergic nerve activity during sleep is increased after bedrest, but other factors, such as loss of body sodium and a lower plasma volume, may also be involved.

Chavarri, M.; Ganguly, A.; Luetscher, J. A.; Zager, P. G.

1977-01-01

356

Circadian rhythms and mood: Opportunities for multi-level analyses in genomics and neuroscience: Circadian rhythm dysregulation in mood disorders provides clues to the brain's organizing principles, and a touchstone for genomics and neuroscience.  

PubMed

In the healthy state, both circadian rhythm and mood are stable against perturbations, yet they are capable of adjusting to altered internal cues or ongoing changes in external conditions. The dual demands of stability and flexibility are met by the collective properties of complex neural networks. Disruption of this balance underlies both circadian rhythm abnormality and mood disorders. However, we do not fully understand the network properties that govern the crosstalk between the circadian system and mood regulation. This puzzle reflects a challenge at the center of neurobiology, and its solution requires the successful integration of existing data across all levels of neural organization, from molecules, cells, circuits, network dynamics, to integrated mental function. This essay discusses several open questions confronting the cross-level synthesis, and proposes that circadian regulation, and its role in mood, stands as a uniquely tractable system to study the causal mechanisms of neural adaptation. Also watch the Video Abstract. Editor's suggested further reading in BioEssays Major depressive disorder: A loss of circadian synchrony? Abstract. PMID:24853393

Li, Jun Z

2014-03-01

357

A Circadian Clock in Antarctic Krill: An Endogenous Timing System Governs Metabolic Output Rhythms in the Euphausid Species Euphausia superba  

PubMed Central

Antarctic krill, Euphausia superba, shapes the structure of the Southern Ocean ecosystem. Its central position in the food web, the ongoing environmental changes due to climatic warming, and increasing commercial interest on this species emphasize the urgency of understanding the adaptability of krill to its environment. Krill has evolved rhythmic physiological and behavioral functions which are synchronized with the daily and seasonal cycles of the complex Southern Ocean ecosystem. The mechanisms, however, leading to these rhythms are essentially unknown. Here, we show that krill possesses an endogenous circadian clock that governs metabolic and physiological output rhythms. We found that expression of the canonical clock gene cry2 was highly rhythmic both in a light-dark cycle and in constant darkness. We detected a remarkable short circadian period, which we interpret as a special feature of the krill's circadian clock that helps to entrain the circadian system to the extreme range of photoperiods krill is exposed to throughout the year. Furthermore, we found that important key metabolic enzymes of krill showed bimodal circadian oscillations (?9–12 h period) in transcript abundance and enzymatic activity. Oxygen consumption of krill showed ?9–12 h oscillations that correlated with the temporal activity profile of key enzymes of aerobic energy metabolism. Our results demonstrate the first report of an endogenous circadian timing system in Antarctic krill and its likely link to metabolic key processes. Krill's circadian clock may not only be critical for synchronization to the solar day but also for the control of seasonal events. This study provides a powerful basis for the investigation into the mechanisms of temporal synchronization in this marine key species and will also lead to the first comprehensive analyses of the circadian clock of a polar marine organism through the entire photoperiodic cycle.

Teschke, Mathias; Wendt, Sabrina; Kawaguchi, So; Kramer, Achim; Meyer, Bettina

2011-01-01

358

Rhythms.  

ERIC Educational Resources Information Center

Presents selected resources for elementary and secondary education that relate to rhythms, including literary rhythms, natural rhythms, and musical rhythms. Includes Web sites, CD-ROMs and software, videos, books, audio materials, magazines, professional resources, and suggested classroom activities. (LRW)

Online-Offline, 2000

2000-01-01

359

Stocking density affects circadian rhythms of locomotor activity in African catfish, Clarias gariepinus.  

PubMed

The effect of stocking density on the locomotor activity of African catfish C. gariepinus under different light regimes was investigated. C. gariepinus were stocked under different densities (1, 5, or 10 fish/tank), and their locomotor activity recorded under light-dark (LD), constant light (LL), constant darkness (DD), and LD-reversed (DL) regimens. Under the LD cycle, catfish showed a crepuscular activity pattern, irrespective of stocking density, with most of the daily activity concentrated around the light-onset and light-offset times. When fish were subjected to DD, all 4 tanks with medium (5 fish) and high (10 fish) stocking densities showed circadian rhythmicity, with an average period (?) of 23.3???0.5 and 24.6???0.5?h, respectively. In contrast, only 2 low (1 fish) density tanks showed free-running rhythms. Under LL, activity levels decreased significantly in comparison with levels observed under LD and DD. Moreover, fish of 1, 2, and 3 out of the 4 tanks with low, medium, and high densities, respectively, showed free-running rhythms under these conditions. When the photocycle was reversed (DL), fish of 3, 2, and 4 out of the 4 tanks with low, medium, and high stocking densities, respectively, showed gradual resynchronization to the new phase, and transient cycles of activity were observed. These results suggest that stocking density of fish affected the display of circadian rhythmicity and the intensity of activity levels. Thus, fish kept in higher densities showed more robust rhythmicity and higher levels of daily activity, indicating that social interactions may have an influence on behavioral patterns in the African catfish. PMID:21895490

Vera, Luisa Mar A; Al-Khamees, Sami; Herv, Migaud

2011-11-01

360

Dipper and non-dipper blood pressure 24-hour patterns: circadian rhythm-dependent physiologic and pathophysiologic mechanisms.  

PubMed

Neuroendocrine mechanisms are major determinants of the normal 24-h blood pressure (BP) pattern. At the central level, integration of the major driving factors of this temporal variability is mediated by circadian rhythms of monoaminergic systems in conjunction with those of the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, opioid, renin-angiotensin-aldosterone, plus endothelial systems and specific vasoactive peptides. Humoral secretions are typically episodic, coupled either to sleep and/or the circadian endogenous (suprachiasmatic nucleus) central pacemaker clock, but exhibiting also weekly, monthly, seasonal, and annual periodicities. Sleep induction and arousal are influenced also by many hormones and chemical substances that exhibit 24-h variation, e.g., arginine vasopressin, vasoactive intestinal peptide, melatonin, somatotropin, insulin, steroids, serotonin, corticotropin-releasing factor, adrenocorticotropic hormone, thyrotropin-releasing hormone, endogenous opioids, and prostaglandin E2, all with established effects on the cardiovascular system. As a consequence, physical, mental, and pathologic stimuli that activate or inhibit neuroendocrine effectors of biological rhythmicity may also interfere with, or modify, the temporal BP structure. Moreover, immediate adjustment to exogenous components/environment demands by BP rhythms is modulated by the circadian-time-dependent responsiveness of biological oscillators and their neuroendocrine effectors. This knowledge contributes to a better understanding of the pathophysiology of abnormalities of the 24-h BP pattern and level and their correction through circadian rhythm-based chronotherapeutic strategies. PMID:23002916

Fabbian, Fabio; Smolensky, Michael H; Tiseo, Ruana; Pala, Marco; Manfredini, Roberto; Portaluppi, Francesco

2013-03-01

361

Prolonged Bioluminescence Monitoring in Mouse Ex Vivo Bone Culture Revealed Persistent Circadian Rhythms in Articular Cartilages and Growth Plates  

PubMed Central

The bone is a metabolically active organ which undergoes repeated remodeling cycles of bone resorption and formation. In this study, we revealed a robust and extremely long-lasting circadian rhythm in ex vivo culture maintained for over six months from the femoral bone of a PERIOD2Luciferase mouse. Furthermore, we also identified robust circadian clocks in flat bones. High- or low-magnification real-time bioluminescence microscopic imaging revealed that the robust circadian rhythms emanated from the articular cartilage and the epiphyseal cartilage within the growth plate of juvenile animals. Stimulation by forskolin or dexamethasone treatment caused type 0 phase resetting, indicating canonical entraining properties of the bone clock. Together, our findings from long-term ex vivo culture revealed that “tissue-autonomous” circadian rhythm in the articular cartilage and the growth plate of femoral bone functions for several months even in an organ culture condition, and provided a useful in vitro assay system investigating the role of the biological clock in bone formation or development.

Fujiwara, Hiroyoshi; Umemura, Yasuhiro; Tsuchiya, Yoshiki; Shirai, Toshiharu; Oda, Ryo; Inokawa, Hitoshi; Kubo, Toshikazu; Yagita, Kazuhiro

2013-01-01

362

The pattern of the circadian rhythm of pancreatic secretion in fed pigs.  

PubMed

The pattern of the circadian rhythm of pancreatic secretion was studied in four 6- to 7-wk-old intact male pigs that were kept in metabolic cages under 12 h light:12 h dark cycles and fed three times a day at 0800, 1500, and 2200. Three 24-h collections of pancreatic juice and blood were begun at 0800 every 2nd day during 5 d. A biphasic pattern of the exocrine pancreas was detected. Secretions during the first phase (postprandial peak) contained large amounts of protein and enzymes, and secretions appeared immediately after feed ingestion. Secretions during the second phase (between meals) had lesser amounts (P < .001) of protein and enzymes, but were of longer duration (P < .001). The output of protein and trypsin activity were generally correlated (P < .001) with each other, but the correlation of either with the volume outflow were small. However, these variables were correlated (P < .01) with the volume outflow at night during the second phase. Plasma concentrations of insulin and glucose increased after each meal, but the increase was significant (P < .05) only for insulin. Insulin and glucose concentrations were correlated (P < .01) with each other after the meals at 0800 and 1500. The results indicated a biphasic pattern of the exocrine pancreas and a monophasic pattern of the endocrine pancreas in pigs. The regulation of these patterns seems to vary during the 24-h period. Furthermore, feed enhanced secretion, but it did not seem to be the only factor controlling the circadian pattern. PMID:8586600

Thaela, M J; Pierzynowski, S G; Jensen, M S; Jakobsen, K; Weström, B R; Karlsson, B W

1995-11-01

363

Circadian rhythm of autonomic activity in non diabetic offsprings of type 2 diabetic patients  

PubMed Central

The aim of the present study was to evaluate, by heart rate variability (HRV) with 24-hours ECG Holter (HRV), the circadian autonomic activity in offspring of type 2 diabetic subjects and the relation with insulin-resistance. METHODS: 50 Caucasian offsprings of type 2 diabetic subjects were divided in two groups: insulin-resistant offsprings (IR) and non insulin-resistant offsprings (NIR). Autonomic nervous activity was studied by HRV. Time domain and spectral analysis (low frequency, LF, and high frequency, HF, provide markers of sympathetic and parasympathetic modulation when assessed in normalized units) were evaluated. RESULTS. Time domain showed a reduction of total SDNN in IR (p < 0.001) and NIR (p 0.047) versus controls. Spectral analysis showed a total and night LF higher in IR and NIR than in control group (all p < 0.001). CONCLUSION. In frequency domain, the analysis of sympathetic (LF) and parasympathetic (HF) component evidenced an association between the offspring of type 2 diabetic subjects and a sympathetic overactivity. A global reduction and alteration of circadian rhythm of autonomic activity are present in offspring of type 2 diabetic patients with and without insulin resistance. The data of our study suggested that an autonomic impairment is associated with the familiarity for type 2 diabetes independently to insulin resistance and that an impairment of autonomic system activity could precede the insulin resistance.

Fiorentini, A; Perciaccante, A; Paris, A; Serra, P; Tubani, L

2005-01-01

364

Alterations in endogenous circadian rhythm of core temperature in senescent Fischer 344 rats  

NASA Technical Reports Server (NTRS)

We assessed whether alterations in endogenous circadian rhythm of core temperature (CRT) in aging rats are associated with chronological time or with a biological marker of senescence, i.e., spontaneous rapid body weight loss. CRT was measured in male Fischer 344 (F344) rats beginning at age 689 days and then continuously until death. Young rats were also monitored. The rats were housed under constant dim red light at 24-26 degrees C, and core temperature was recorded every 10 min via biotelemetry. The CRT amplitude of the body weight-stable (presenescent) old rats was significantly less than that of young rats at all analysis periods. At the onset of spontaneous rapid weight loss (senescence), all measures of endogenous CRT differed significantly from those in the presenescent period. The suprachiasmatic nucleus (a circadian pacemaker) of the senescent rats maintained its light responsiveness as determined by an increase in c-fos expression after a brief light exposure. These data demonstrate that some characteristics of the CRT are altered slowly with chronological aging, whereas others occur rapidly with the onset of senescence.

McDonald, R. B.; Hoban-Higgins, T. M.; Ruhe, R. C.; Fuller, C. A.; Horwitz, B. A.

1999-01-01

365

Circadian rhythms are not involved in the regulation of circannual reproductive cycles in a sub-tropical bird, the spotted munia.  

PubMed

Circannual rhythms regulate seasonal reproduction in many vertebrates. The present study investigated whether circannual reproductive phenotypes (rhythms in growth of gonads and molt) were generated independently of the circadian clocks in the subtropical non-photoperiodic spotted munia (Lonchura punctulata). Birds were subjected to light:dark (LD) cycles with identical light but varying dark hours, such that the period of LD cycle (T) equaled 16 h (T16; 12 h L:4 h D), 21 h (T21; 12 h L:9 h D), 24 h (T24; 12 h L:12 h D) and 27 h (T27; 12 h L:15 h D), or to continuous light (LL, 24 h L:0 h D) at ~18°C. During the ~21 month exposure, munia underwent at least two cycles of gonadal development and molt; changes in body mass were not rhythmic. This was similar to the occurrence of annual cycles in reproduction and molt observed in wild birds. A greater asynchrony between circannual cycles of gonad development and molt indicated their independent regulation. Females showed reproductive rhythms with similar circannual periods, whilst in males, circannual periods measured between peak gonadal size were longer in T21 and T24 than in T16 or T27. This suggested a sex-dependent timing of annual reproduction in the spotted munia. Also, food availability periods may not influence the circannual timing of reproduction, as shown by the results on the rhythm in gonadal growth and regression in munia under T-photocycles and LL that provided differential light (feeding) hours. Further, a short-term experiment revealed that activity-rest patterns in munia were synchronized with T-photocycles, but were arrhythmic under LL. We conclude that circadian rhythms are not involved in the timing of the annual reproductive cycle in the spotted munia. PMID:24803462

Budki, Puja; Malik, Shalie; Rani, Sangeeta; Kumar, Vinod

2014-07-15

366

Assessment of sleep patterns, energy expenditure and circadian rhythms of skin temperature in patients with acute coronary syndrome  

PubMed Central

Summary Background There is no simple and practical way to monitor sleep patterns in patients in acute care units. We designed this study to assess sleep patterns, energy expenditure and circadian rhythms of patients’ skin temperature in the coronary care unit (CCU) utilizing a new portable device. Material/Methods The SenseWear Armband (SWA) was used to record sleep duration, distribution over 24 hr, energy expenditure and the circadian rhythms of skin temperature in 46 patients with acute coronary syndrome (ACS) for the first 24 hr in the CCU and upon transfer to the ward. An advanced analysis was used to extract and compare data associated with the above variables in the two settings. Results Patients in the CCU had a reduced night’s sleep duration (5.6±2.2 hr) with more frequent and significantly shorter night sessions (p=0.015) than patients in the ward. Energy expenditure and METs (metabolic equivalents of a task) were significantly lower in the CCU than in the ward. However, the midline-estimating statistic of rhythm (MESOR) and acrophase for skin temperature did not exhibit any significant difference between the two settings. Conclusions Patients with ACS have sleep fragmentation and shorter nocturnal sleep duration in the CCU compared to the ward. On the other hand, there was no difference in the circadian rhythms of skin temperature between patients in the CCU and the general wards.

Otair, Hadil Al; Al-shamiri, Mustafa; Bahobail, Mohammed; Sharif, Munir M.; BaHammam, Ahmed S.

2011-01-01

367

Effects of menstrual cycle phase and oral contraceptives on alertness, cognitive performance, and circadian rhythms during sleep deprivation  

NASA Technical Reports Server (NTRS)

The influence of menstrual cycle phase and oral contraceptive use on neurobehavioral function and circadian rhythms were studied in healthy young women (n = 25) using a modified constant routine procedure during 24 h of sleep deprivation. Alertness and performance worsened across sleep deprivation and also varied with circadian phase. Entrained circadian rhythms of melatonin and body temperature were evident in women regardless of menstrual phase or oral contraceptive use. No significant difference in melatonin levels, duration, or phase was observed between women in the luteal and follicular phases, whereas oral contraceptives appeared to increase melatonin levels. Temperature levels were higher in the luteal phase and in oral contraceptive users compared to women in the follicular phase. Alertness on the maintenance of wakefulness test and some tests of cognitive performance were poorest for women in the follicular phase especially near the circadian trough of body temperature. These observations suggest that hormonal changes associated with the menstrual cycle and the use of oral contraceptives contribute to changes in nighttime waking neurobehavioral function and temperature level whereas these factors do not appear to affect circadian phase.

Wright, K. P. Jr; Badia, P.; Czeisler, C. A. (Principal Investigator)

1999-01-01

368

Lability and diversity of circadian rhythms of cotton rats Sigmodon hispidus.  

PubMed

Cotton rats (Sigmodon hispidus) were maintained from birth in constant LD 14:10 photoperiods and temperatures. Wheel running was diurnal for 6 of 13 juvenile rats and nocturnal for most others. Most diurnal rats eventually added nocturnal activity components. In constant darkness the activity rhythms of adult rats free-ran with a period of 23.2 +/- 0.3 h; in constant illumination the period was 24.7 +/- 0.1 h, in conformation to Aschoff's rule for nocturnal rodents. Some previously nocturnal adult rats eventually adopted stable diurnal activity cycles and other were successively nocturnal, diurnal for 6 mo, and then nocturnal again while maintained in the LD 14:10 photoperiod. The existence of multiple activity types, as well as the spontaneous inversions from nocturnal to diurnal status substantiate and extend field observations of this species. Seasonal inversions from nocturnal to diurnal activity, previously attributed to fluctuating environmental conditions, may also be subject to regulation by endogenous processes. It is suggested that spontaneous phase reversals in activity reflect changes in entrainment of circadian pacemakers by the light-dark cycle or altered relations between such pacemakers and the overt activity rhythm. PMID:6338744

Johnston, P G; Zucker, I

1983-03-01

369

Maximum entropy spectral analysis for circadian rhythms: theory, history and practice.  

PubMed

There is an array of numerical techniques available to estimate the period of circadian and other biological rhythms. Criteria for choosing a method include accuracy of period measurement, resolution of signal embedded in noise or of multiple periodicities, and sensitivity to the presence of weak rhythms and robustness in the presence of stochastic noise. Maximum Entropy Spectral Analysis (MESA) has proven itself excellent in all regards. The MESA algorithm fits an autoregressive model to the data and extracts the spectrum from its coefficients. Entropy in this context refers to "ignorance" of the data and since this is formally maximized, no unwarranted assumptions are made. Computationally, the coefficients are calculated efficiently by solution of the Yule-Walker equations in an iterative algorithm. MESA is compared here to other common techniques. It is normal to remove high frequency noise from time series using digital filters before analysis. The Butterworth filter is demonstrated here and a danger inherent in multiple filtering passes is discussed. PMID:23844660

Dowse, Harold B

2013-01-01

370

Occurrence of circadian rhythms in hairy root cultures grown under controlled conditions.  

PubMed

Hairy roots obtained by transformation via Agrobacterium rhizogenes provide an artificial plant material devoid of aerial parts with high growth on hormone-free media. Fundamental knowledge of hairy root physiology is essential to develop and control its culture. In contrast to shake-flask cultures, a bioreactor set-up combined with on-line data logging provides an efficient tool to study rapid physiological variations in hairy root cultures. Datura innoxia hairy roots were grown in a bioreactor equipped with on-line data analyses of pH, dissolved oxygen (pO2), conductivity, oxygen, and carbon dioxide. The experiments were done at a constant temperature and in the absence of light cues. The results obtained showed that the carbon dioxide evolution rate (CER) presented regular oscillations during the culture. Similar oscillations were also observed for the oxygen uptake rate (OUR). These signals were treated mathematically to look for the existence of a rhythm. An autocorrelation function was used to detect any periodic components. The results demonstrate that hairy root respiration exhibited peaks of 1 day. These oscillations, having a period of about 24 h, were also observed in pH and conductivity signals, although not for the pO2 signal. The data acquired in the absence of hairy roots showed that the observed periodic behavior was not an artifact. No effect on rhythms was observed by the imposition of an external "day/night" cycle. The fact that oscillations persisted in the absence of external stimuli, with a free-running period of 24 h, suggests that a circadian rhythm exists in hairy roots of D. innoxia. PMID:15532042

Lanoue, Arnaud; Shakourzadeh, Khalil; Marison, Ian; Laberche, Jean-Claude; Christen, Philippe; Sangwan-Norreel, Brigitte; Boitel-Conti, Michèle

2004-12-20

371

Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans  

PubMed Central

Background The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep-wake cycle has not been fully characterized. Methodology/Principal Findings We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days) and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity ‘room’ light (?90–150 lux) or moderate light supplemented with bright light (?10,000 lux) for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h). Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17–94%) and after bright light by 52% (range 12–84%), as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness. Conclusions/Significance Alterations in the timing of the sleep-wake cycle and associated bright or moderate light exposure can lead to changes in phase and reduction of circadian amplitude which are consistent across multiple variables but differ between individuals. These data have implications for our understanding of circadian organization and the negative health outcomes associated with shift-work, jet-lag and exposure to artificial light.

Dijk, Derk-Jan; Duffy, Jeanne F.; Silva, Edward J.; Shanahan, Theresa L.; Boivin, Diane B.; Czeisler, Charles A.

2012-01-01

372

Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation  

NASA Technical Reports Server (NTRS)

We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Claustrat, B.; Gharib, C.; Gauquelin-Koch, G.

2001-01-01

373

Circadian temperature and melatonin rhythms, sleep, and neurobehavioral function in humans living on a 20-h day  

NASA Technical Reports Server (NTRS)

The interaction of homeostatic and circadian processes in the regulation of waking neurobehavioral functions and sleep was studied in six healthy young subjects. Subjects were scheduled to 15-24 repetitions of a 20-h rest/activity cycle, resulting in desynchrony between the sleep-wake cycle and the circadian rhythms of body temperature and melatonin. The circadian components of cognitive throughput, short-term memory, alertness, psychomotor vigilance, and sleep disruption were at peak levels near the temperature maximum, shortly before melatonin secretion onset. These measures exhibited their circadian nadir at or shortly after the temperature minimum, which in turn was shortly after the melatonin maximum. Neurobehavioral measures showed impairment toward the end of the 13-h 20-min scheduled wake episodes. This wake-dependent deterioration of neurobehavioral functions can be offset by the circadian drive for wakefulness, which peaks in the latter half of the habitual waking day during entrainment. The data demonstrate the exquisite sensitivity of many neurobehavioral functions to circadian phase and the accumulation of homeostatic drive for sleep.

Wyatt, J. K.; Ritz-De Cecco, A.; Czeisler, C. A.; Dijk, D. J.

1999-01-01

374

The effects on human sleep and circadian rhythms of 17 days of continuous bedrest in the absence of daylight  

NASA Technical Reports Server (NTRS)

As part of a larger bedrest study involving various life science experiments, a study was conducted on the effects of 17 days of continuous bedrest and elimination of daylight on circadian rectal temperature rhythms, mood, alertness, and sleep (objective and diary) in eight healthy middle-aged men. Sleep was timed from 2300 to 0700 hours throughout. Three 72-hour measurement blocks were compared: ambulatory prebedrest, early bedrest (days 5-7), and late bedrest (days 15-17). Temperature rhythms showed reduced amplitude and later phases resulting from the bedrest conditions. This was associated with longer nocturnal sleep onset latencies and poorer subjectively rated sleep but with no reliable changes in any of the other sleep parameters. Daily changes in posture and/or exposure to daylight appear to be important determinants of a properly entrained circadian system.

Monk, T. H.; Buysse, D. J.; Billy, B. D.; Kennedy, K. S.; Kupfer, D. J.

1997-01-01

375

Effects of chronic expression of the HIV-induced protein, transactivator of transcription, on circadian activity rhythms in mice, with or without morphine  

PubMed Central

Patients with human immunodeficiency virus (HIV) infection exhibit changes in sleep patterns, motor disorders, and cognitive dysfunction; these symptoms may be secondary to circadian rhythm abnormalities. Studies in mice have shown that intracerebral injection of an HIV protein, transactivator of transcription (Tat), alters the timing of circadian rhythms in a manner similar to light. Therefore, we tested the hypothesis that chronic Tat expression alters circadian rhythms, especially their entrainment to a light-dark (LD) cycle, by using transgenic mice in which Tat expression in the brain was induced via a doxycycline (DOX)-sensitive, glial fibrillary-associated, protein-restricted promoter. Because opiate substance abuse, which shares comorbidity with HIV infection, also disrupts sleep, a final experiment assessed the effects of morphine exposure on circadian rhythms in wild-type and Tat transgenic mice. Mice housed in cages equipped with running wheels were fed chow with or without DOX. Experiment 1 revealed a small but significant (P < 0.05) difference between groups in the phase angle of entrainment and a 15% decrease in the wheel running in the DOX group (P < 0.005). During exposure to constant darkness, DOX did not alter the endogenous period length of the circadian rhythm. Experiment 2 investigated the effect of DOX on circadian rhythms in wild-type and Tat(+) mice during exposure to a normal or phase-shifted LD cycle, or morphine treatment without any change in the LD cycle. Tat induction significantly decreased wheel running but did not affect entrainment to the normal or shifted LD cycle. Morphine decreased wheel running without altering the phase angle of entrainment, and the drug's effects were independent of Tat induction. In conclusion, these findings suggest that chronic brain expression of Tat decreases locomotor activity and the amplitude of circadian rhythms, but does not affect photic entrainment or reentrainment of the murine circadian pacemaker.

Duncan, Marilyn J.; Bruce-Keller, Annadora J.; Conner, Clayton; Knapp, Pamela E.; Xu, Ruquiang; Nath, Avindra; Hauser, Kurt F.

2008-01-01

376

Effects of chronic expression of the HIV-induced protein, transactivator of transcription, on circadian activity rhythms in mice, with or without morphine.  

PubMed

Patients with human immunodeficiency virus (HIV) infection exhibit changes in sleep patterns, motor disorders, and cognitive dysfunction; these symptoms may be secondary to circadian rhythm abnormalities. Studies in mice have shown that intracerebral injection of an HIV protein, transactivator of transcription (Tat), alters the timing of circadian rhythms in a manner similar to light. Therefore, we tested the hypothesis that chronic Tat expression alters circadian rhythms, especially their entrainment to a light-dark (LD) cycle, by using transgenic mice in which Tat expression in the brain was induced via a doxycycline (DOX)-sensitive, glial fibrillary-associated, protein-restricted promoter. Because opiate substance abuse, which shares comorbidity with HIV infection, also disrupts sleep, a final experiment assessed the effects of morphine exposure on circadian rhythms in wild-type and Tat transgenic mice. Mice housed in cages equipped with running wheels were fed chow with or without DOX. Experiment 1 revealed a small but significant (P < 0.05) difference between groups in the phase angle of entrainment and a 15% decrease in the wheel running in the DOX group (P < 0.005). During exposure to constant darkness, DOX did not alter the endogenous period length of the circadian rhythm. Experiment 2 investigated the effect of DOX on circadian rhythms in wild-type and Tat(+) mice during exposure to a normal or phase-shifted LD cycle, or morphine treatment without any change in the LD cycle. Tat induction significantly decreased wheel running but did not affect entrainment to the normal or shifted LD cycle. Morphine decreased wheel running without altering the phase angle of entrainment, and the drug's effects were independent of Tat induction. In conclusion, these findings suggest that chronic brain expression of Tat decreases locomotor activity and the amplitude of circadian rhythms, but does not affect photic entrainment or reentrainment of the murine circadian pacemaker. PMID:18784333

Duncan, Marilyn J; Bruce-Keller, Annadora J; Conner, Clayton; Knapp, Pamela E; Xu, Ruquiang; Nath, Avindra; Hauser, Kurt F

2008-11-01

377

Effects of 10 h time zone changes on female flight attendants' circadian rhythms of body temperature, alertness, and visual search  

Microsoft Academic Search

The aim of the study was to analyse the effects of rapid time zone changes on the circadian rhythms of flight attendants. The mean age of the 40 female subjects was 30·0 (SD=6·9) years. Measurements of oral temperature, alertness, and visual search were performed at two hour intervals two days before the flight from Helsinki to Los Angeles, during the

S. SUVANTO; M. HÄRMÄ; J. ILMARINEN; M. PARTINEN

1993-01-01

378

Elimination of Angiostrongylus costaricensis larvae in feces from experimentally infected Swiss mice: circadian rhythm and correlation with survival  

Microsoft Academic Search

Angiostrongylus costaricensis is a nematode which harbors mesentery arteries of rodents. In these animals, a circadian rhythm of elimination of first-stage\\u000a larvae (L1) and a relation between the amount of L1 in feces and survival are unknown. We assessed fecal elimination of A. costaricensis L1 from experimentally infected Swiss mice and tried to correlate L1 elimination with survival. Thirteen Swiss

Graciele Vivian de Azevedo; Rubens Rodriguez; Sérgio Machado Porto; Carlos Graeff-Teixeira; Fernando Fornari

2011-01-01

379

The Clinical Outcome of Acute Myocardial Infarction Is Related to the Circadian Rhythm of Myocardial, lnfarction Onset  

Microsoft Academic Search

In order to study whether the circadian rhythm of acute myocardial infarc tion (AMI) onset has any impact on the clinical outcome, in terms of enzymati cally estimated infarct size, circulatory arrest from ventricular tachyarrhyth mias, and in-hospital mortality, the authors studied a representative population of 10,791 AMIs treated in the same center between 1973 and 1987. In 6,763 cases

Ole Hansen; Bengt W. Johansson; Bo Gullberg

1993-01-01

380

Ramelteon (TAK-375) Accelerates Reentrainment of Circadian Rhythm after a Phase Advance of the Light-Dark Cycle in Rats  

Microsoft Academic Search

In vivo pharmacological effects of ramelteon (TAK-375), a novel, highly MT1\\/MT2-selective receptor agonist, were studied in rats to determine ramelteon’s ability to reentrain the circadian rhythm after an abrupt phase advance. Experiments were also conducted to assess the potential cognitive side effects of ramelteon and its potential to become a drug of abuse. After an abrupt 8-h phase shift, ramelteon

Keisuke Hirai; Muneto Kita; Hiroyuki Ohta; Hisao Nishikawa; Yuu Fujiwara; Shigenori Ohkawa; Masaomi Miyamoto

2005-01-01

381

Entrainment of the circadian rhythm in the locomotor activity of Mus booduga by red and white light.  

PubMed

The role of red light (greater than 610 nm) and white incandescent light in entraining the circadian locomotor activity rhythm of the field mouse Mus booduga has been studied using different light intensities. Red light of less than 150 microW/cm2 caused negative masking and greater than 150 microW/cm2 caused entrainment. Such intensity dependent masking and entrainment were also obtained with white incandescent light. PMID:3850025

Viswanathan, N; Chandrashekaran, M K

1985-01-01

382

Cardiac-Specific Mutation of Clock Alters the Quantitative Measurements of Physical Activities without Changing Behavioral Circadian Rhythms  

PubMed Central

Even though peripheral circadian oscillators in the cardiovascular system are known to exist, the daily rhythms of the cardiovascular system are mainly attributed to autonomic or hormonal inputs under the control of the central oscillator, the suprachiasmatic nucleus (SCN). In order to examine the role of peripheral oscillators in the cardiovascular system, we used a transgenic mouse where the Clock gene is specifically disrupted in cardiomyocytes. In this cardiomyocyte-specific CLOCK mutant (CCM) mouse model, the circadian input from the SCN remains intact. Both CCM and wild-type (WT) littermates displayed circadian rhythms in wheel-running behavior. However, the overall wheel-running activities were significantly lower in CCM mice compared to WT over the course of 5 weeks, indicating that CCM mice either have lower baseline physical activities or they have lower physical adaptation abilities because daily wheel running, like routine exercise, induces physical adaptation over a period of time. Upon further biochemical analysis, it was revealed that the diurnal oscillations of phosphorylation states of several kinases and protein expression of the L-type voltage-gated calcium channel (L-VGCC) ?1D subunit found in WT hearts were abolished in CCM hearts, indicating that in mammalian hearts, the daily oscillations of the activities of these kinases and L-VGCCs were downstream elements of the cardiac core oscillators. However, the phosphorylation of p38 MAPK exhibited robust diurnal rhythms in both WT and CCM hearts, indicating that cardiac p38 could be under the influence of the central clock through neurohormonal signals or be part of the circadian input pathway in cardiomyocytes. Taken together, these results indicate that the cardiac core oscillators have an impact in regulating circadian rhythmicities and cardiac function.

Ko, Michael L.; Shi, Liheng; Tsai, Ju-Yun; Young, Martin E.; Neuendorff, Nichole; Earnest, David J.; Ko, Gladys Y.-P.

2011-01-01

383

Health Impact of Fasting in Saudi Arabia during Ramadan: Association with Disturbed Circadian Rhythm and Metabolic and Sleeping Patterns  

PubMed Central

Background Muslims go through strict Ramadan fasting from dawn till sunset for one month yearly. These practices are associated with disturbed feeding and sleep patterns. We recently demonstrated that, during Ramadan, circadian cortisol rhythm of Saudis is abolished, exposing these subjects to continuously increased cortisol levels. Hypothesis Secretory patterns of other hormones and metabolic parameters associated with cortisol, and insulin resistance, might be affected during Ramadan. Protocol Ramadan practitioners (18 males, 5 females; mean age ±SEM?=?23.16±1.2 years) were evaluated before and two weeks into Ramadan. Blood was collected for measurements of endocrine and metabolic parameters at 9 am (±1 hour) and again twelve hours later. Results In Ramadan, glucose concentration was kept within normal range, with a significant increase in the morning. Mean morning concentration of leptin was significantly higher than pre-Ramadan values (p?=?0.001), in contrast to that of adiponectin, which was significantly lower (p<0.001). These changes were associated with increased insulin resistance in morning and evening. Concentrations of hsCRP were lower during Ramadan than those during regular living conditions, however, normal circadian fluctuation was abolished (p?=?0.49). Even though means of liver enzymes, total bilirubin, total protein and albumin were all decreased during Ramadan, statistically lower means were only noted for GGT, total protein, and albumin (p?=?0.018, 0.002 and 0.001 respectively). Discussion Saudi Ramadan practitioners have altered adipokine patterns, typical of insulin resistance. The noted decreases of hsCRP, liver enzymes, total protein, and albumin, are most likely a result of fasting, while loss of circadian rhythmicity of hsCRP is probably due to loss of circadian cortisol rhythm. Conclusions Modern Ramadan practices in Saudi Arabia, which are associated with evening hypercortisolism, are also characterized by altered adipokines patterns, and an abolished hsCRP circadian rhythm, all likely to increase cardiometabolic risk.

Ajabnoor, Ghada M.; Bahijri, Suhad; Borai, Anwar; Abdulkhaliq, Altaf A.; Al-Aama, Jumana Y.; Chrousos, George P.

2014-01-01

384

Elucidation of the Role of Clp Protease Components in Circadian Rhythm by Genetic Deletion and Overexpression in Cyanobacteria  

PubMed Central

In the cyanobacterium Synechococcus elongatus PCC7942, KaiA, KaiB, and KaiC are essential elements of the circadian clock, and Kai-based oscillation is thought to be the basic circadian timing mechanism. The Kai-based oscillator coupled with transcription/translation feedback and other intercellular factors maintains the stability of the 24-hour period in vivo. In this study, we showed that disruption of the Clp protease family genes clpP1, clpP2, and clpX and the overexpression of clpP3 cause long-period phenotypes. There were no significant changes in the levels of the clock proteins in these mutants. The overexpression of clpX led to a decrease in kaiBC promoter activity, the disruption of the circadian rhythm, and eventually cell death. However, after the transient overexpression of clpX, the kaiBC gene expression rhythm recovered after a few days. The rhythm phase after recovery was almost the same as the phase before clpX overexpression. These results suggest that the core Kai-based oscillation was not affected by clpX overexpression. Moreover, we showed that the overexpression of clpX sequentially upregulated ribosomal protein subunit mRNA levels, followed by upregulation of other genes, including the clock genes. Additionally, we found that the disruption of clpX decreased the expression of the ribosomal protein subunits. Finally, we showed that the circadian period was prolonged following the addition of a translation inhibitor at a low concentration. These results suggest that translational efficiency affects the circadian period and that clpX participates in the control of translation efficiency by regulating the transcription of ribosomal protein genes.

Kitayama, Yohko; Kondo, Takao

2013-01-01

385

A study on circadian rhythm disorder of rat lung tissue caused by mechanical ventilation induced lung injury.  

PubMed

Ventilator-induced lung injury (VILI), the most serious complication of mechanical ventilation therapy, is an excessive inflammatory response in lung tissue characterized by infiltration of inflammatory cells and overproduction of inflammatory mediators. The pathogenesis of VILI is very complex. It is becoming increasingly evident that disruption of circadian rhythm affects the immune response. Whether the pathogenesis of VILI is associated with circadian rhythm disruption has not been reported. In this study, we establish VILI model in SD rat by performing an endotracheal intubation and placing the rat on a mechanical ventilator (tidal volume of 40 ml/kg or 10 ml/kg without positive end-expiratory pressure). To examine the effect of VILI on clock gene expression, real-time quantitative PCR was performed to measure bmal1, clock, per2 and Rev-erb? mRNA expression. We found that Rev-erb? mRNA was significantly decreased in high tide volume mechanical ventilation group compared with spontaneous group, the same as REV-ERB? protein product which was tested by Western blot approach. Stimulation of REV-ERB? activity by SR9009 greatly diminished VILI-induced lung edema, inflammatory cell infiltration and the production of the pro-inflammatory cytokine TNF-?. Collectively, our findings are the first to show that REV-ERB? plays an important role in VILI and inflammation, and circadian rhythm disorder in inflammation response may be a novel pathogenesis of VILI. PMID:24355794

Li, Huan; Wang, Chunxiao; Hu, Jiaqi; Tan, Junyuan

2014-02-01

386

The effects of combining serotonin reuptake inhibition and 5-HT7 receptor blockade on circadian rhythm regulation in rodents.  

PubMed

Disruption of circadian rhythms may lead to mood disorders. The present study investigated the potential therapeutic utility of combining a 5-HT7 antagonist with a selective serotonin (5-HT) reuptake inhibitor (SSRI), the standard of care in depression, on circadian rhythm regulation. In tissue explants of the suprachiasmatic nucleus (SCN) from PER2::LUC mice genetically modified to report changes in the expression of a key clock protein, the period length of PER2 bioluminescence was shortened in the presence of AS19, a 5-HT7 partial agonist. This reduction was blocked by SB269970, a selective 5-HT7 antagonist. The SSRI, escitalopram, had no effect alone on period length, but a combination with SB269970, yielded significant increases. Dosed in vivo, escitalopram had little impact on the occurrence of activity onsets in rats given access to running wheels, whether the drug was given acutely or sub-chronically. However, preceding the escitalopram treatment with a single acute dose of SB269970 produced robust phase delays, in keeping with the in vitro explant data. Taken together, these findings suggest that the combination of an SSRI and a 5-HT7 receptor antagonist has a greater impact on circadian rhythms than that observed with either agent alone, and that such a multimodal approach may be of therapeutic value in treating patients with poor clock function. PMID:23276605

Westrich, Ligia; Sprouse, Jeffrey; Sánchez, Connie

2013-02-17

387

Circadian Rhythms in Exercise Performance: Implications for Hormonal and Muscular Adaptation  

PubMed Central

Almost all physiological and biochemical processes within the human body follow a circadian rhythm (CR). In humans, the suprachiasmatic nucleus regulates sleep- wake cycle and other daily biorhythms in line with solar time. Due to such daily physiological fluctuations, several investigations on neuromuscular performance have reported a distinct CR during exercise. Generally, peak performances have been found to occur in the early evening, at approximately the peak of core body temperature. The increase in core body temperature has been found to increase energy metabolism, improve muscle compliance and facilitate actin-myosin crossbridging. In addition, steroidal hormones such as testosterone (T) and cortisol (C) also display a clear CR. The role of T within the body is to maintain anabolism through the process of protein synthesis. By contrast, C plays a catabolic function and is involved in the response of stress. Due to the anabolic and catabolic nature of both T and C, it has been postulated that a causal relationship may exist between the CR of T and C and muscular performance. This review will therefore discuss the effects of CR on physical performance and its implications for training. Furthermore, this review will examine the impact of muscular performance on CR in hormonal responses and whether could variations in T and C be potentially beneficial for muscular adaptation. Key points A distinct CR can be observed in physical performance. CR of exercise performance is highly associated with CR in core body temperature Both T and C display a clear CR, however, the current evidence does not show a clear relationship with neuromuscular adaptations. TST is able to induce changes in physical performance variables at the particular time point, but not for the circadian profile of T and C.

Teo, Weipeng; Newton, Michael J.; McGuigan, Michael R.

2011-01-01

388

Disruption of behavioral circadian rhythms induced by psychophysiological stress affects plasma free amino acid profiles without affecting peripheral clock gene expression in mice.  

PubMed

Disordered circadian rhythms are associated with various psychiatric conditions and metabolic diseases. We recently established a mouse model of a psychophysiological stress-induced chronic sleep disorder (CSD) characterized by reduced amplitude of circadian wheel-running activity and sleep-wake cycles, sleep fragmentation and hyperphagia. Here, we evaluate day-night fluctuations in plasma concentrations of free amino acids (FAA), appetite hormones and prolactin as well as the hepatic expression of circadian clock-related genes in mice with CSD (CSD mice). Nocturnal increases in wheel-running activity and circadian rhythms of plasma prolactin concentrations were significantly disrupted in CSD mice. Hyperphagia with a decreased leptin/ghrelin ratio was found in CSD mice. Day-night fluctuations in plasma FAA contents were severely disrupted without affecting total FAA levels in CSD mice. Nocturnal increases in branched-chain amino acids such as Ile, Leu, and Val were further augmented in CSD mice, while daytime increases in Gly, Ala, Ser, Thr, Lys, Arg, His, Tyr, Met, Cys, Glu, and Asn were significantly attenuated. Importantly, the circadian expression of hepatic clock genes was completely unaffected in CSD mice. These findings suggest that circadian clock gene expression does not always reflect disordered behavior and sleep rhythms and that plasma FFA profiles could serve as a potential biomarker of circadian rhythm disorders. PMID:24971530

Oishi, Katsutaka; Yamamoto, Saori; Itoh, Nanako; Miyazaki, Koyomi; Nemoto, Tadashi; Nakakita, Yasukazu; Kaneda, Hirotaka

2014-07-18

389

Effects of systemically applied nAChR?7 agonists and antagonists on light-induced phase shifts of hamster circadian activity rhythms.  

PubMed

Many physiological systems in mammals are linked to the body's master circadian rhythm in the sleep/wake cycle and dysfunctions in this rhythm has been associated with neurological diseases such as major depression, Alzheimer's Disease and schizophrenia. There is some evidence that nicotinic cholinergic input to the master circadian pacemaker, the suprachiasmatic nucleus, may modulate circadian activity rhythms, but data employing in vivo preparations is sparse. Therefore we examined the ability of intraperitoneally applied nicotinic agonists and antagonists relatively selective for the ?7 nicotinic receptor to modulate light-induced phase shifts of hamster circadian wheel running rhythms. Hamsters were maintained in constant darkness and exposed to light pulses early and late in their active period, mimicking dusk and dawn respectively, which elicited phase delays and advances of their circadian wheel running rhythms. The ?7 receptor antagonists bPiDDB (0.03-3mg/kg) and methyllacaconitine (0.1-1mg/kg) inhibited both light- induced phase advances and delays of circadian wheel running rhythms by as much as 75% versus vehicle injections. In contrast, systemic injections of the ?7 agonists PHA 543613 and ABT107, both at 0.156-2.5mg/kg, had no effect on light induced phase advances or delays. Further, ?7 nicotinic receptors were identified in the hamster suprachiasmatic nucleus using an antibody that recognizes ?7 nicotinic receptors. These results clearly identify the ability of ?7 nicotinic receptor antagonists to inhibit light-entrainment of the hamster circadian pacemaker. Therefore, nicotinic compounds may be useful for the treatment of circadian dysfunction associated with neurological diseases. PMID:24388152

Gannon, Robert L; Garcia, David A; Millan, Mark J

2014-06-01

390

UNC79 and UNC80, Putative Auxiliary Subunits of the NARROW ABDOMEN Ion Channel, Are Indispensable for Robust Circadian Locomotor Rhythms in Drosophila  

PubMed Central

In the fruit fly Drosophila melanogaster, a network of circadian pacemaker neurons drives daily rhythms in rest and activity. The ion channel NARROW ABDOMEN (NA), orthologous to the mammalian sodium leak channel NALCN, functions downstream of the molecular circadian clock in pacemaker neurons to promote behavioral rhythmicity. To better understand the function and regulation of the NA channel, we have characterized two putative auxiliary channel subunits in Drosophila, unc79 (aka dunc79) and unc80 (aka CG18437). We have generated novel unc79 and unc80 mutations that represent strong or complete loss-of-function alleles. These mutants display severe defects in circadian locomotor rhythmicity that are indistinguishable from na mutant phenotypes. Tissue-specific RNA interference and rescue analyses indicate that UNC79 and UNC80 likely function within pacemaker neurons, with similar anatomical requirements to NA. We observe an interdependent, post-transcriptional regulatory relationship among the three gene products, as loss of na, unc79, or unc80 gene function leads to decreased expression of all three proteins, with minimal effect on transcript levels. Yet despite this relationship, we find that the requirement for unc79 and unc80 in circadian rhythmicity cannot be bypassed by increasing NA protein expression, nor can these putative auxiliary subunits substitute for each other. These data indicate functional requirements for UNC79 and UNC80 beyond promoting channel subunit expression. Immunoprecipitation experiments also confirm that UNC79 and UNC80 form a complex with NA in the Drosophila brain. Taken together, these data suggest that Drosophila NA, UNC79, and UNC80 function together in circadian clock neurons to promote rhythmic behavior.

Lear, Bridget C.; Darrah, Eric J.; Aldrich, Benjamin T.; Gebre, Senetibeb; Scott, Robert L.; Allada, Ravi

2013-01-01

391

Why the dim light melatonin onset (DLMO) should be measured before treatment of patients with circadian rhythm sleep disorders.  

PubMed

Treatment of circadian rhythm sleep disorders (CRSD) may include light therapy, chronotherapy and melatonin. Exogenous melatonin is increasingly being used in patients with insomnia or CRSD. Although pharmacopoeias and the European food safety authority (EFSA) recommend administering melatonin 1-2 h before desired bedtime, several studies have shown that melatonin is not always effective if administered according to that recommendation. Crucial for optimal treatment of CRSD, melatonin and other treatments should be administered at a time related to individual circadian timing (typically assessed using the dim light melatonin onset (DLMO)). If not administered according to the individual patient's circadian timing, melatonin and other treatments may not only be ineffective, they may even result in contrary effects. Endogenous melatonin levels can be measured reliably in saliva collected at the patient's home. A clinically reliably DLMO can be calculated using a fixed threshold. Diary and polysomnographic sleep-onset time do not reliably predict DLMO or circadian timing in patients with CRSD. Knowing the patient's individual circadian timing by assessing DLMO can improve diagnosis and treatment of CRSD with melatonin as well as other therapies such as light or chronotherapy, and optimizing treatment timing will shorten the time required to achieve results. PMID:24388969

Keijzer, Henry; Smits, Marcel G; Duffy, Jeanne F; Curfs, Leopold M G

2014-08-01

392

Epidemiological evidence for the links between sleep, circadian rhythms and metabolism  

PubMed Central

Summary Epidemiological data reveal parallel trends of decreasing sleep duration and increases in metabolic disorders such as obesity, diabetes and hypertension. There is growing evidence that these trends are mechanistically related. The seasonal expression of the thrifty genotype provides a conceptual framework to connect circadian and circannual rhythms, sleep and metabolism. Experimental studies have shown sleep deprivation to decrease leptin, increase ghrelin, increase appetite, compromise insulin sensitivity and raise blood pressure. Habitually short sleep durations could lead to insulin resistance by increasing sympathetic nervous system activity, raising evening cortisol levels and decreasing cerebral glucose utilization that over time could compromise ?-cell function and lead to diabetes. Prolonged short sleep durations could lead to hypertension through raised 24-h blood pressure and increased salt retention resulting in structural adaptations and the entrainment of the cardiovascular system to operate at an elevated pressure equilibrium. Cross-sectional and longitudinal epidemiological studies have shown associations between short sleep duration and obesity, diabetes and hypertension. If metabolic changes resulting from sleep restriction function to increase body weight, insulin resistance and blood pressure then interventions designed to increase the amount and improve the quality of sleep could serve as treatments and as primary preventative measures for metabolic disorders.

Gangwisch, J. E.

2014-01-01

393

[Effect of modafinil on electroretinograms of Lycosa tarentula in relation visual circadian rhythm (Araneae, Lycosidae)].  

PubMed

Injections of modafinil, a drug able to induce in vertebrates an awakening effect via an effective central alpha 1-adrenergic tone, induce modifications of the amplitude and latency of electroretinograms (ERGs) in the spider Lycosa tarentula, during dark adaptation. Results of experiments are different from one eye type to another as circadian activity rhythms of the retinae also differ. Modafinil induces a decrease of diurnal amplitudes and has no effect on nocturnal amplitudes of ERGs of anterior-lateral eyes; in the case of posterior-median eyes, the amplitudes are increased in daytime as well as at night. Prazosin, antagonist of alpha 1-adrenergic receptors, injected after modafinil, induces a decrease of the amplitudes of ERGs in the same eyes. These results are discussed in relation to the visual activity of this species, both diurnal and nocturnal. The concepts of waking state versus sleep are not precisely characterized in arachnids, so that the effects of modafinil on L. tarentula may not be considered like those described in vertebrates. PMID:10101611

Carricaburu, P; Muñoz-Cuevas, A

1998-01-01

394

L-5-hydroxytryptophan resets the circadian locomotor activity rhythm of the nocturnal Indian pygmy field mouse, Mus terricolor.  

PubMed

We report that L-5-hydroxytryptophan (5-HTP), a serotonin precursor, resets the overt circadian rhythm in the Indian pygmy field mouse, Mus terricolor, in a phase- and dose-dependent manner. We used wheel running to assess phase shifts in the free-running locomotor activity rhythm. Following entrainment to a 12:12 h light-dark cycle, 5-HTP (100 mg/kg in saline) was intraperitoneally administered in complete darkness at circadian time (CT)s 0, 3, 6, 9, 12, 15, 18, and 21, and the ensuing phase shifts in the locomotor activity rhythm were calculated. The results show that 5-HTP differentially shifts the phase of the rhythm, causing phase advances from CT 0 to CT 12 and phase delays from CT 12 to CT 21. Maximum advance phase shift was at CT 6 (1.18?±?0.37 h) and maximum delay was at CT 18 (-2.36?±?0.56 h). No extended dead zone is apparent. Vehicle (saline) at any CT did not evoke a significant phase shift. Investigations with different doses (10, 50, 100, and 200 mg/kg) of 5-HTP revealed that the phase resetting effect is dose-dependent. The shape of the phase-response curve (PRC) has a strong similarity to PRCs obtained using some serotonergic agents. There was no significant increase in wheel-running activity after 5-HTP injection, ruling out behavioral arousal-dependent shifts. This suggests that this phase resetting does not completely depend on feedback of the overt rhythmic behavior on the circadian clock. A mechanistic explanation of these shifts is currently lacking. PMID:22331255

Basu, Priyoneel; Singaravel, Muniyandi; Haldar, Chandana

2012-03-01

395

l-5-hydroxytryptophan resets the circadian locomotor activity rhythm of the nocturnal Indian pygmy field mouse, Mus terricolor  

NASA Astrophysics Data System (ADS)

We report that l-5-hydroxytryptophan (5-HTP), a serotonin precursor, resets the overt circadian rhythm in the Indian pygmy field mouse, Mus terricolor, in a phase- and dose-dependent manner. We used wheel running to assess phase shifts in the free-running locomotor activity rhythm. Following entrainment to a 12:12 h light-dark cycle, 5-HTP (100 mg/kg in saline) was intraperitoneally administered in complete darkness at circadian time (CT)s 0, 3, 6, 9, 12, 15, 18, and 21, and the ensuing phase shifts in the locomotor activity rhythm were calculated. The results show that 5-HTP differentially shifts the phase of the rhythm, causing phase advances from CT 0 to CT 12 and phase delays from CT 12 to CT 21. Maximum advance phase shift was at CT 6 (1.18 ± 0.37 h) and maximum delay was at CT 18 (-2.36 ± 0.56 h). No extended dead zone is apparent. Vehicle (saline) at any CT did not evoke a significant phase shift. Investigations with different doses (10, 50, 100, and 200 mg/kg) of 5-HTP revealed that the phase resetting effect is dose-dependent. The shape of the phase-response curve (PRC) has a strong similarity to PRCs obtained using some serotonergic agents. There was no significant increase in wheel-running activity after 5-HTP injection, ruling out behavioral arousal-dependent shifts. This suggests that this phase resetting does not completely depend on feedback of the overt rhythmic behavior on the circadian clock. A mechanistic explanation of these shifts is currently lacking.

Basu, Priyoneel; Singaravel, Muniyandi; Haldar, Chandana

2012-03-01

396

Effect of Antipyretic Drugs on the Circadian Rhythm in Body Temperature of Rats. Revision 1.  

National Technical Information Service (NTIS)

In many series, including the laboratory rat, body temperature varies on a circadian (24 hour) basis. There is considerable evidence that the circadian rise in body temperature is attributable to an elevation in thermoregulatory set-point. We hypothesized...

W. E. Scales M. J. Kluger

1986-01-01

397

Lack of circadian rhythm of plasma concentrations of vasoactive intestinal peptide in patients with orthotopic heart transplants.  

PubMed Central

OBJECTIVE--To study the circadian pattern of plasma concentrations of vasoactive intestinal peptide (VIP) in patients with orthotopic heart transplants. Circulating VIP is known to have neural and immunological sources. PATIENTS AND METHODS--13 patients with orthotopic heart transplants were studied 12-53 months (mean 31.8 months) after operation. All were haemodynamically compensated and had no histological evidence of rejection. They were being treated with cyclosporin, azathioprine, and prednisone. Ten healthy individuals were studied as controls. Circulating VIP was assayed six times within a 24h period. Time qualified data were analysed by ANOVA and the cosinor method. Student's t test for unpaired data and Bingham's test for cosinor-derived parameters were used for statistical comparisons. RESULTS--Plasma concentrations of VIP were lower in the patients with orthotopic heart transplants than in the controls (p < 0.001). ANOVA and the cosinor method respectively showed a statistically significant within-day variability and circadian rhythm in the controls but not in the patients with heart transplants. DISCUSSION--The low plasma concentrations of VIP in the patients with heart transplants could be the result of the lack of contribution by the cardiac VIPergic fibres, a reduction of VIP release by the pharmacologically suppressed immune system, the inhibitory effects of cyclosporin on neural function and humoral secretions, and the effects of negative feedback on VIP release of high concentrations of atrial natriuretic peptide. The lack of the circadian rhythm suggests a structural disorder, which should be further investigated.

Cugini, P; Lucia, P; Scibilia, G; Di Palma, L; Cioli, A R; Cianetti, A; Gasbarrone, L; Canova, R; Marino, B

1993-01-01

398

The frequency of the spontaneous behavioral response in Paramecium tetraurelia is simultaneously modulated by both ultradian and circadian rhythms  

Microsoft Academic Search

The behavioral response of Paramecium tetraurelia is due to changes in the direction of swimming, which is initiated by the generation of an action potential that causes the re-orientation of the ciliary beat. The frequency of spontaneous behavioral responses displays an ultradian <