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Circadian preferences with emphasis on school-age children
Kasalová, Michaela ; Janečková, Denisa (advisor) ; Drda Morávková, Alena (referee)
Bakalářská práce: Cirkadiánní preference se zaměřením na děti žákovského věku Řešitel: Michaela Kasalová Vedoucí práce: PhDr. Denisa Janečková, Ph.D. Abstract: Chronobiology (name comes from a Greek word chronos = time) is a scientific field engaged in biological rhythms that have a specific cycle with a different length of period. The most important rhythms for a human body are circadian rhythms with a period approximately 24 hours. These rhythms influence individual timing of physiological, biochemical and psychological variables technically called chronotypes. Objectives of this bachelor's work are to map the chronotypes from a historical view and to outline individual types, their specifications, their biological principle and their connection with the circadian rhythms and a sleeping cycle. Differences between chronotypes are not only among individual persons but they are changing during specific ages, therefore I focus on school-age children. Today's school system forces pupils to a certain rhythm, not necessarily well functioning with their internal natural biorhythm, and can influence results as well as study options.
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Interventions of Nurses in Relation to the Prevention of Sleep Deprivation of Patients Hospitalized at the Intensive
Růžičková, Martina ; Jirkovský, Daniel (advisor) ; Vaňková, Milena (referee)
There are many studies about problematic of sleep connected with shift work. However, only few studies devoted to the conditions for good rest and sleep in patients hospitalized in intensive care units. Insufficient or poor quality sleep and relaxation are the most common problems reported by patients that were hospitalized at intensive care units (ICU). Sleep is one of the basic biological needs of human. Sleep deficit can lead to psychical and psychological dysfunction that can affect the healing process. The diploma thesis is dealing with sleeping issues of patients hospitalized especially at intensive care units. The aim of the study is to determining the opinions of nurses that work at intensive care units on meeting the needs relating with sleep and rest of hospitalized patients and mapping, what interventions they use to prevent of occurrence of difficulties in this area. The theoretical part at first describes physiology of sleep and biological rhythms, then sleep disorders, then factors affecting sleep along with the consequences of the lack of sleep and last nursing process for patients with sleep disorder. The empirical part presents the results of questionnaire survey and then results of executed statistical analysis. Established hypothesis not have been assumed in results of survey...
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Circadian regulation of STAT3 protein in the SCN and it's activation by leptin in the SCN, other parts of hypothalamus and the pineal gland
Moníková, Veronika ; Bendová, Zdeňka (advisor) ; Jelínková, Dana (referee)
JAK/STAT signaling pathway is one of the most studied intracellular cascades transmitting signals from the extracellular environment to the cell nucleus in order to affect expression of target genes. Circadian clocks localized in the suprachiasmatic nuclei (SCN) of the hypothalamus are sensitive especially to light but they can respond to non-photic stimuli such as growth factors, opioids, leptin and cytokines that have been demonstrated to perform its function via the JAK/STAT signaling pathway. The recent findings of our laboratory demonstrated that STAT3 protein is highly produced by SCN of rat. Primary aim of our experiments was to test the circadian regulation of STAT3 production in SCN and describe the effect of exogenously administered leptin on STAT3 phosphorylation in the SCN, pineal gland and hypothalamic structures responsible for regulated feeding behavior and energy metabolism. Because activation of leptin receptors may stimulate a number of other signaling cascades, we chose phosphorylated forms of kinase ERK1/2 and GSK-3β as other markers of intracellular changes after administration of leptin in the studied structures. Our results proved rhythmic production of STAT3 protein in SCN of rat and indicated circadian regulation of sensitivity to leptin in hypothalamic structures. The data...
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The influence of endotoxin lipopolysaccharide on the circadian system
Štěrbová, Petra ; Bendová, Zdeňka (advisor) ; Svobodová, Irena (referee)
The biological clock are responsible for entraining of circadian rhytms in many physiological and behavioral functions, including the activity of immune system. In mammals, the biological clock are located in the suprachiasmatic nuclei of the hypothalamus and also on the periphery. The main oscillator in suprachiamatic nuclei synchronizes the phases of the peripheral oscillators in tissues and the other brain areas and it also drives synthesis of melatonin in the pineal gland. Its endogenous period Tau (τ) is being synchronized with external 24-hour day under normal conditions, mostly by the light-dark cycles during the day and night and also by non-photic stimuli. By the application of endotoxin, disruption of normal endogenous conditions in organism causes activation of the immune response, behavioral changes and phase shifts of the circadian rhythmicity. This work examines effect of acute application endotoxin lipopolysaccharid on the cellular signaling cascades in the cells of suprachiasmatic nuclei and pineal gland. Our data indicate, that levels of phosphorylated forms of kinases GSK3β, ERK1/2 and levels of phosphorylated forms transcription factors STAT3 are substantially modificated after administration of lipopolysaccharid in the suprachiasmatic nuclei and especially in the pineal gland of...
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Clock genes in mammalian circadian pacemaker
Cimerová, Veronika ; Bendová, Zdeňka (advisor) ; Polidarová, Lenka (referee)
The behavior of mammals and their physiological processes are dependent on the daily rhythms. These rhythms are controlled by an endogenous circadian clock that responds to light/dark cycles of environment. In mammals, the circadian clocks, are arranged hierarchically, and work in almost all cells and tissues. Suprachiasmatic nuclei (SCN) in the hypothalamus are at the top of the hierarchy and work as a major circadian pacemaker. This work presents the clock genes that have been discovered in the last twenty years in the SCN of mammals. The first chapter focuses on the general mechanism of circadian rhythms and structure of the SCN. The second chapter describes the transcriptional-translational feedback loops that are an essential part of the proper function of the circadian clock, and function of individual genes is briefly introduced in this chapter. The following chapters already include a chronological characterization of Clock, Bmal1, Period and Cryptochrome genes, as they were discovered. If the clock gene expresses different function from the clockwork mechanism, it is briefly introduced in the final paragraph on the chapter. The final chapters deal with other molecules, casein kinases, ROR and REV-ERB receptors that affect its function expression and degradation of circadian genes in the...
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Expression of AMPA glutamate receptor subunits in the suprachiasmatic nucleus of the rat
Červená, Kateřina ; Bendová, Zdeňka (advisor) ; Zemková, Hana (referee)
The main mammalian circadian pacemaker stored in suprachiasmatic nuclei of the hypothalamus (SCN) is adapted to changes in the external environement by synchronization of its endogenous period with periodic changes of light and dark during day and night. The information about light travels via glutamatergic retinohypothalamic tract to the ventrolateral part of the SCN. Activation of ionotropic glutamate receptors in this area provably mediates the transfer of information about light on the transcriptional mechanism of light-sensitive cells. The role of the NMDA type of ionotropic glutamate receptors is well studied in this field and it is known that some NMDA receptor subunits show a circadian rhythm and an increased expression after a light pulse. Signalization via AMPA type receptors is much less elucidated. The aim of this thesis was to determine which AMPA receptor subunits are expressed in the SCN of the rat and if these subunits show a daily rhythm of expression and a reactivity to light pulse, as well as to outline the possible roles of distinct AMPA receptor subunits in the SCN. Keywords: circadian rhythms, suprachiasmatic nuclei, glutamate receptors, AMPA
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Circadian clock during ontogenesis
Olejníková, Lucie ; Sumová, Alena (advisor) ; Hock, Miroslav (referee)
Circadian system enables adaptation of organisms to periodic changes in environment on the Earth. In mammals, it consists of central pacemaker in the suprachiasmatic nuclei (SCN) of hypothalamus and of oscillators that reside in other brain areas as well as in the peripheral organs and tissues. Ontogenetic development of the circadian system is a gradual process and the most dramatic changes undergo during the late embryonic and early postnatal stage. For its proper function, not only the morphological development of its individual parts, but also development of their entrainment to external environment and among each other, is important. The oscillations in clock gene expressions in the SCN occur already before birth, but in view of the fact that the levels of their protein products are undetectable, at this developmental stage, the ability of SCN to generate these oscillations in vivo has been discussed. After birth, the levels of these proteins rise and the rhythms in clock genes expression achieve the adult-like level at the postnatal age, when the synaptogenesis in the SCN is completed. The presence of a functional maternal circadian system is not necessary for the endogenous development of the SCN clock in pups, because the maternal SCN only entrains the clock and the circadian oscillations thus...
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Synchronization of circadian system during prenatal and early postnatal development
Houdek, Pavel ; Sumová, Alena (advisor) ; Novotná, Růžena (referee)
One of the few attributes common to almost all living organisms is an ability to generate and maintain endogenous rhythms, which are controlled by a biological clock. The processes, which recur with a period of about 24 hours, are known as the circadian rhythms. The circadian clock controls rhythms of molecular, physiological as well as behavioral processes and adapts their activity to regularly appearing changes in day and night or season. In case of mammals, central oscillator is located in the hypothalamic suprachiasmatic nuclei (SCN). The SCN clock entrains rhythms of peripheral oscillators located in cells of other tissues. The central oscillator itself is synchronized with external environment mainly by a light-dark cycle, however, other cues can entrain the SCN clock as well. For example, during prenatal development, entrainment of a fetal clock is entirely dependent on non-photic cues derived from maternal organism. This study aimed to investigate a mechanism of the communication between the maternal and fetal central oscillators. A hypothesis was tested whether maternal melatonin may play a role in entrainment of the circadian clock in the fetal SCN. Furthermore, a mechanism, how melatonin may entrain the fetal clock was investigated at molecular level. The results provided evidence, that...
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The role of glucocorticoids in circadian system
Tejkal, Karel ; Sumová, Alena (advisor) ; Forman, Martin (referee)
Glucocorticoids are mammalian steroid hormones secreted from the adrenal gland. The basal levels of glucocorticoids show a pronounced diurnal rhythm with maximum at the beginning of the active period and minimum at its end. Glucocorticoids have an influence over a variety of metabolic functions and their secretion is tightly regulated. This regulation also depends on the circadian system, which utilizes glucocorticoids to entrain the peripheral tissues by inducing rhythmic gene expression. The mechanisms by which glucocorticoids influence mammalian circadian system has not yet been precisely defined, especially concerning the influence of glucocorticoid signalling on gene expression in different tissues and the dynamics of glucocorticoid receptor (GR) occupancy. This thesis studies the influence of ablation of glucocorticoid signalization induced by adrenalectomy on the clock gene expression of in the central clock in the suprachiasmatic nucleus and peripheral clocks in the hippocampus and distal colon. The effect of adrenalectomy on gene expression is compared with the effect of restricting the feeding time, which has also been shown to affect glucocorticoid levels in the body. Other experiments were aimed at elucidating impact of changing the activity of GR on gene expression using synthetic GR...
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