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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Effect of diet textural characteristics on the temporal rhythms of feeding in rats

Mok, Elise. January 1997 (has links)
Dietary selection involves the process of relating the postingestional consequences of eating a food to its sensory characteristics. Diet texture, the most plausible sensory characteristic affecting ingestion, may play an important role in the control of food selection. In this study, we compared the circadian rhythmicity of protein- and carbohydrate-rich diet ingestion of adult male Wistar rats presented with diets in different textural forms (high-protein powder and high-carbohydrate granular (HPP-HCG) diets vs. high-protein granular and high-carbohydrate powder (HPG-HCP) diets) during 15 days. Rats fed HPP-HCG diets selected significantly less protein (kcal) vs. rats fed HPG-HCP diets, during the 24 h, 12 h dark phase and the 4 h early and late dark phases. Carbohydrate intakes of the two dietary groups were not significantly different. Total caloric intake for HPG-HCP group was significantly higher than that of HPP-HCG group during the 24 h and 12 h dark phase. In conclusion, macronutrient-rich diets presented in different textural forms alter the circadian rhythmicity of protein-rich diet ingestion and total energy intake.
122

Regulation and Synchronization of the Master Circadian Clock by Purinergic Signaling from Suprachiasmatic Nucleus Astrocytes

Womac, Alisa Diane 2012 August 1900 (has links)
Molecular, cellular, and physiological processes within an organism are set to occur at specific times throughout the day. The timing of these processes is under control of a biological clock. Nearly all organisms on Earth have biological clocks, ranging from unicellular bacteria and fungi to multicellular plants, insects, reptiles, fish, birds, and mammals. The biological clock is an endogenous time-keeping mechanism that generates the onset of many processes and coordinates the phases of processes over 24 hours. While the biological clock allows these organisms to maintain roughly 24-hour, or circadian, timing in daily processes, many organisms have the ability to set their clocks, or entrain them, to changes in light. In mammals, the suprachiasmatic nucleus (SCN) is the master biological clock that entrains daily physiological and behavioral rhythms to the appropriate times of day and night. The SCN is located in the hypothalamus and contains thousands of neurons and glia that function in coordinating system-level physiological rhythms that are entrained to environmental light cues. Many of these neurons and glia are individual circadian oscillators, and the cellular mechanisms that couple them into ensemble oscillations are emerging. Adenosine triphosphate (ATP) is a transmitter involved in local communication among astrocytes and between astrocytes and neurons. ATP released from astrocytes may play a role in SCN cellular communication and synchrony. Extracellular ATP accumulated rhythmically in the rat SCN in vivo, and ATP released from rat SCN astrocytes in vitro was rhythmic, with a periodicity near 24 hours. ATP released from mouse SCN astrocytes was circadian, and disruption of the molecular clock abolished rhythmic extracellular ATP accumulation. SCN astrocyte cultures with disrupted molecular clocks also had marked reductions in total ATP accumulation compared to SCN astrocyte cultures with functional biological clocks. Furthermore, ATP-induced calcium transients were rhythmic, and this rhythmic purinergic sensitivity was abolished in clock mutant astrocytes. Pharmacological blockade of purinergic signaling, with antagonists of both the P2X7 and P2Y1 receptors, led to a gradual reduction in the amplitude of coordinated ATP accumulation over three days. These purinergic receptor antagonists, as expected, led to a reduction in calcium responses of SCN astrocytes to ATP and led to a dampening of clock gene expression rhythms as determined by PER2::LUC bioluminescence reporting in SCN astrocytes. These data demonstrate that astrocytes of the mammalian SCN rhythmically release ATP and are rhythmically sensitive to ATP in a manner dependent on their intrinsic molecular clock. Ensemble rhythmicity of SCN astrocytes is, in turn, dependent on that rhythmic purinergic signaling via both P2X and P2Y classes of ATP receptors. These results are indicative of a functional role for ATP accumulation within the SCN, with astrocytes releasing ATP every 24 hours for continual signaling onto astrocytes and neurons to maintain daily coordinated synchrony of the clocks in these cells.
123

The role of melatonin in human thermoregulation and sleep / by Cameron J. van den Heuvel.

Heuvel, Cameron J. van den January 1998 (has links)
Bibliography: leaves 162-197. / vii, 216 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / To determine the effects of melatonin on sleepiness and body temperature under conditions that better approximated the endogenous melatonin profile. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1998?
124

An investigation into the genetic basis of migration timing in Chinook salmon (Oncorhynchus tshawytscha) /

O'Malley, Kathleen Gallen, January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.
125

Comparison of circadian rhythm in cardiac and non-cardiac chest pain

Shockey, Margaret Lynne. January 1900 (has links)
Thesis (M.A.)--Northern Kentucky University, 2008. / Made available through ProQuest. Publication number: AAT 1459962. ProQuest document ID: 1674094541. Includes bibliographical references (p. 27-29)
126

Circadian rhythms, fatigue, and manpower scheduling /

Pearson, Kristen A. January 2004 (has links) (PDF)
Thesis (M.S. in Operations Research)--Naval Postgraduate School, December 2004. / Thesis advisor(s): Nita Lewis Miller. Includes bibliographical references (p. 87-89). Also available online.
127

Sleep and circadian rhythms in children with attention deficit-hyperactivity disorder : before and after stimulant treatment /

Cohen-Zion, Mairav. January 2005 (has links)
Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2005. / Vita. Includes bibliographical references (leaves 117-127).
128

Daily activity rhythms in the flying squirrel, Glaucomys volans

DeCoursey, P. J. January 1959 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 148-162).
129

Ontogeny of approach and escape responses and circadian activity rhythms in domestic chicks

Miller, Don Edward, January 1966 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
130

The mitogen-activated protein kinase (MAPK) pathway a signaling conduit for photic entrainment of the central mammalian circadian clock /

Butcher, Gregory Quinn. January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2007 May 10

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