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Topic: Circadian

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	Circadian rhythm - Wikipedia, the free encyclopedia
		Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including human beings.
		Circadian rhythms are believed to have originated in the earliest cells to provide protection for replicating DNA, from high ultraviolet radiation during day-time.
		The simplest known circadian clock is that of the prokaryotic cyanobacteria.
	en.wikipedia.org /wiki/Circadian (1352 words)

	Encyclopedia :: encyclopedia : Circadian rhythm (Site not responding. Last check: 2007-10-30)
		Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including humans.
		The circadian "clock" in mammals is primarily located in the suprachiasmatic nucleus (SCN), a distinct group of cells located in the hypothalamus.
		Recently, evidence has emerged that circadian rhythms are found in many cells in the body--outside of the SCN "master clock." Liver cells, for example, appear to respond to feeding rather than light.
	www.hallencyclopedia.com /Circadian_rhythm (750 words)

	Circadian rhythm sleep disorder - Wikipedia, the free encyclopedia
		Circadian rhythm sleep disorders are a family of sleep disorders affecting the timing of sleep.
		Humans have biological rhythms, known as circadian rhythms, which are controlled by a biological clock and work on a daily time scale.
		Persistent circadian rhythm sleep disorders such as DSPS are believed to be caused by a reduced ability to reset the sleep/wake cycle in response to environmental time cues.
	en.wikipedia.org /wiki/Circadian_rhythm_sleep_disorders (611 words)

	Circadian Rhythms
		Four well-known genes that affect circadian period are per in fruit flies, frq in bread mold, tau in golden hamsters, and clock in domestic mice.
		The circadian systems of diurnal and nocturnal organisms do not seem to differ, and the adoption of diurnal or nocturnal niches is believed to be determined by mechanisms located downstream from the pacemaker.
		Circadian rhythm of body temperature: we have investigated the mean level, amplitude, phase, and robustness of the daily rhythm of body temperature in a variety of mammalian species, including rodents, dogs, sheep, and horses.
	www.circadian.org /biorhyt.html (1827 words)

	Circadian Rhythms
		Circadian rhythms, biological rhythms with a period of approximately 24 hours, appear to evolve from the adaptation of life to light/dark and temperature cycles on the Earth.
		Circadian rhythms have been observed among major phyla, from cyanobacteria, algae, fungi, plants, to animals, including insects, vertebrates such as fish, mouse, humans.
		In other words, circadian clocks act like the watches and clocks you have: they are able to keep 24 hours a day, and when you travel to different time zones, they are able to adjust to the local time.
	www.ou.edu /wanglab/Circadian.html (571 words)

	The genetic basis of circadian rhythms in animals
		Circadian rhythms are biological rhythms which approximate the period of twenty-four hours, or more accurately, the alternation between day and night (Hasting, 1994; Kornhauser, et al., 1996).
		This group of scientists believe that circadian rhythms may consist of one, or several, specialised elements isolated from the house-keeping genes whose principal function is to generate a circadian rhythm (Hastings, 1994).
		In his circadian model, he proposes that the mechanism of the biological clock is related to the periodic expression of genes which appear to be cell autonomous and whose properties are uniquely rhythmic (Takahashi, 1993).
	www.geocities.com /Area51/Dimension/8211/JSS/00002.htm (2545 words)

	Sleep and Circadian Rhythms (Site not responding. Last check: 2007-10-30)
		Circadian rhythms are regular changes in mental and physical characteristics that occur in the course of a day (circadian is Latin for "around a day").
		Most circadian rhythms are controlled by the body’s biological "clock." This clock, called the suprachiasmatic nucleus or SCN, is actually a pair of pinhead-sized brain structures that together contain about 20,000 neurons.
		Circadian rhythms can be affected to some degree by almost any kind of external time cue, such as the beeping of your alarm clock, the clatter of a garbage truck, or the timing of your meals.
	healthlink.mcw.edu /article/922567322.html (728 words)

	Center for Sleep and Circadian Biology-Northwestern University
		Circadian rhythms help coordinate the timing of our internal bodily functions, including sleep, as well as our interactions with the external world.
		The pharmaceutical industry is now investigating the importance of circadian rhythms for the timing of drug delivery and is interested in developing drugs that could affect the circadian clock of humans, as well as agricultural plants and animals.
		Advances in our understanding of circadian rhythms will have broad economic implications since information from fundamental research programs on circadian rhythms can be expected to be transferred readily to the medical, business and agricultural sectors.
	www.northwestern.edu /cscb/about.html (442 words)

	circadian
		The central circadian pacemaker is science's term for the body's biological clock.
		Circadian clocks are believed to confer an advantage to plants, but the nature of that advantage has been unknown.
		Their internal circadian clocks are set to go to bed at 11pm or later, and they naturally wake up later as well.
	www.mongabay.com /igapo/biotech/circadian.html (3360 words)

	Circadian Rhythms
		In short, circadian rhythms show several fundamental features: 1) they are endogenously generated oscillations that repeat with a frequency of close to 24 hours, 2) they exhibit homeostasis of period, including temperature compensation, 3) they are synchronized by periodic environmental signals, with the daily light-dark cycle being the dominant cue used.
		THE MAMMALIAN CIRCADIAN OSCILLATOR: THE SUPRACHIASMATIC NUCLEUS (SCN)
		The cells of the SCN showed prominent circadian variation in their metabolic activity; glucose utilization peaked during the day, when nocturnal rodents were at rest, and fell to a minimum during the night, when the animals were active.
	www.acnp.org /G4/GN401000074/CH074.html (8659 words)

	Overview of Circadian Rhythms
		In mammals, the circadian clock resides in two clusters of nerve cells called the suprachiasmatic nuclei (SCN), which are located in a region at the base of the brain called the anterior hypothalamus.
		To further elucidate the regulation of circadian rhythms, researchers need a better understanding of the nature of circadian signal output from the SCN and of how these output signals may be modified once they reach their target systems.
		Circadian rhythms are self-sustaining (i.e., free running), meaning that they will persist when the organism is placed in an environment devoid of time cues, such as constant light or constant darkness.
	pubs.niaaa.nih.gov /publications/arh25-2/85-93.htm (5585 words)

	Circadian Sleep Disorders Association - FAQ
		Circadian disorders are abnormalities in the body's internal "clock," which regulates when the body gets sleepy and when it's ready to wake up.
		Preliminary research indicates that there is a genetic component to circadian disorders, i.e., they are at least partly and perhaps wholly hereditary.
		The most common circadian disorder is probably delayed sleep phase syndrome (DSPS), which causes a delay of several hours in people's ability to get sleepy and their ability to wake up refreshed.
	www.circadiandisorders.org /faq.html (704 words)

	Circadian Technologies Limited
		Circadian is able to provide funds for further development in addition to providing the management expertise that is essential if the project is to meet its goal of commercialisation.
		Circadian has shareholdings in Optiscan Imaging Limited, Metabolic Pharmaceuticals Limited and Antisense Therapeutics Limited, companies in which Circadian has been involved in providing funding and assistance in their listing.
		Circadian is also the largest shareholder in Zenyth Therapeutics Limited (formerly Amrad Corporation) and a significant shareholder in Avexa Limited, both Australian pharmaceutical research companies.
	www.circadian.com.au (266 words)

	Circadian Rhythm Disorders
		Circadian rhythm disorders are disruptions in a person’s circadian rhythm—a name given to the "internal body clock" that regulates the (approximately) 24-hour cycle of biological processes in animals and plants.
		The circadian "clock" in humans is located mainly in the suprachiasmatic nucleus (SCN), which is a group of cells located in the hypothalamus (a portion of the brain).
		Circadian rhythm disorders are treated based on the kind of disorder that is present.
	www.clevelandclinic.org /health/health-info/docs/3700/3712.asp?index=12115 (485 words)

	The Molecular Genetics of Circadian Clocks
		The daily rhythm of life is maintained by a circadian clock in organisms ranging from bacteria to humans.
		Perhaps the best known rhythms are those that display an approximate 24 hour period length, entrainment of the clock in response to light-dark transitions and a temperature compensation of the period.
		Circadian rhythms are thought to contain at least three elements: a) input pathways(s) relay environmental information to a circadian pacemaker (clock) b) the circadian pacemaker generates the oscillation and c) output pathway(s) through which the pacemaker regulates various output rhythms.
	www.csa.com /discoveryguides/archives/circad.php (1124 words)

	Circadian's Home on the Net
		While their list of covers is extensive and well produced, the original material produced by Circadian is more impressive, illustrating their myriad of musical styles and intelligence in lyrical phrasing and composition.
		Circadian recorded their first studio album in Minneapolis at The Mother of All Music studios with Andy Frey producing.
		Today, with the support of fans and their ever-growing grassroot volunteer campaign in place, Circadian hopes to plant their seed of music in many new cities and venues across the country.
	www.circadianmusic.com /band1.asp (354 words)

	A guideline for analyzing circadian wheel-running behavior in rodents under different lighting conditions
		These rhythms are distinguished by their period length (τ) with circadian (lat: circa diem, around a day) rhythms displaying a τ of approximately 24 hours that evolved in adaptation to the daily rotation of the earth around its axis.
		The circadian clockwork has evolved to improve an organism’s adaptation to its environment and to ensure timed coordination of life-sustaining activities such as feeding, sleeping as well as the coordination of physiological and biochemical mechanisms.
		One circadian cycle is divided into 24 equally sized circadian units (or circadian hours) with one unit being defined as the division of the internal period length (τ) by 24 hours.
	www.biologicalprocedures.com /bpo/arts/1/109/m109.htm (7610 words)

	Keeping Time to Circadian Rhythms (July/August 1990)
		The most well-known circadian rhythm is that of body temperature, which varies daily a degree or two in a healthy person, peaking in late afternoon and troughing in the early morning hours.
		In treating asthma, the circadian rhythms of the lung's airways are now taken into consideration when giving the drug theophylline, used to open airways.
		In experiments, even after being awake more than 20 hours, people free of time cues slept twice as long when they went to bed when their temperature was at its highest (in early evening) than when it was at its lowest (in the early morning).
	www.fda.gov /bbs/topics/CONSUMER/CON00048.html (2643 words)

	Circadian Sleep Disorders Association (Site not responding. Last check: 2007-10-30)
		Circadian sleep disorders affect your body clock and keep you from sleeping and waking at the culturally "normal" times.
		The Circadian Sleep Disorders Association exists to support those affected by circadian sleep disorders, and to provide information on the disorders to the general public.
		If you have a circadian sleep disorder, are friends or family with someone who does, are a researcher or medical worker in the field, or simply find circadian sleep disorders interesting, you are welcome to join our e-mail list, Niteowl.
	www.circadiandisorders.org /index.html (286 words)

	HHMI News: Shedding Light on Circadian Rhythms
		In mammals, the internal circadian clock resides in the brain, and sunlight is the cue that rewinds this clock daily.
		Despite the dramatic impact that the mutation had on circadian biochemistry, the overall circadian locomotor activity rhythms of these mutant flies was surprisingly normal.
		According to Rosbash, these studies show that the role of cryptochrome in circadian function in fruit flies "is simple and uncomplicated, and it lies at the top of the pathway." If cryptochrome does not get light, says Rosbash, the circadian system simply does not work correctly.
	www.hhmi.org /news/takahashi.html (884 words)

	Circadian Rhythms :: About
		Circadian Rhythms exists with the purpose of producing a regular music event for the Auckland Gothic community.
		Circadian Rhythms stands in opposition to the Cult of Personality, the Tyranny of the DJ, and the resultant constant repetition of songs.
		Although Circadian Rhythms itself is made up of a few people, we realise that the community is bigger and more varied than just us.
	www.circadian-rhythms.org /about.html (675 words)

	HHMI News: New Pathway to Understanding Circadian Rhythms
		Circadian rhythms, the patterns of activity that occur on a 24-hour cycle, are important biological regulators in virtually every living creature.
		In charting the circadian rhythms of the mutant flies, Sehgal and her colleagues found that those rhythms were, indeed, disrupted.
		However, we have found that for circadian rhythm effects, the signaling pathway seems to be the same.
	www.hhmi.org /news/sehgal2.html (760 words)

	Circadian definition - Medical Dictionary definitions of popular medical terms
		Circadian: Refers to events occurring within a 24-hour period, in the span of a full (24-hour) day, as in a circadian rhythm.
		Circadian rhythmicity is a fundamental property possessed by all organisms.
		A gene for the biological clock in a mouse was identified and cloned in 1997, the first such gene to be identified at the molecular level in a mammal.
	www.medterms.com /script/main/art.asp?articlekey=6766 (366 words)

	Circadian Rhythms and Clocks (Site not responding. Last check: 2007-10-30)
		In addition to the circadian clock, in Neurospora light regulated genes also control carotenoid (photo-protective pigments) synthesis, spore formation, photoadaptation, and phototropism (growth towards a light source).
		One of the main genes involved in circadian clock regulation in Neurospora is frq (frequency), which encodes the protein, FREQUENCY (FRQ).
		The Molecular Genetics of Circadian Clocks - includes information about the circadian clocks of Cyanobacteria and plants, which are not included in my article.
	www.scienceden.com /mbiology/research/circadian (1636 words)

	Regulation of the Circadian Oscillator in Xenopus Retinal Photoreceptors by Protein Kinases Sensitive to the ...
		Phase-dependent effects of SB 203580 on circadian rhythms of melatonin release from cultured photoreceptor layers.
		Dose-dependent effect of SB 203580 on the phase of the circadian rhythms of melatonin.
		of the circadian oscillator in Xenopus retinal photoreceptors.
	www.jbc.org /cgi/content/full/279/21/22738 (6657 words)

	Circadian Rhythms - Van D. Gooch
		Circadian rhythms are biological process that oscillate with an approximate 24 hour periodicity when there are no external timing cues.
		For example a sleep wake cycle of a mouse in constant dark and with constant temperature; or the leaf movement of a plant in constant dim light and constant temperature.
		Centre for Circadian Biology and Medicine, Northwestern University.
	www.mrs.umn.edu /~goochv/Circadian/circadian.html (505 words)

	Quiz on Circadian Rhythms
		This is a test of your knowledge of circadian rhythms.
		According to the "non-parametric theory of entrainment", entrainment (synchronization) of circadian rhythms by environmental stimuli is achieved by
		The book Circadian Physiology, currently in its second edition, is an excellent introduction to the field of circadian rhythm research for scientists in other fields.
	www.circadian.org /test.html (560 words)

	Joseph Takahashi, Ph.D.
		We have initiated a genetic approach to study the mechanism of circadian rhythms in mammals using the mouse as a model organism.
		The Clock mutation is semidominant and lengthens circadian period by 1 hr in heterozygotes and by 4 hr in homozygotes.
		The delineation of this circadian gene pathway should eventually lead to an understanding of how circadian clocks function and their environmental regulation.
	www.northwestern.edu /neurobiology/faculty/takahashi.html (285 words)

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