Academic literature on the topic 'Ageing Clock'

Methylation levels have been shown to change with age at sites across the human genome. Change at some of these sites is so consistent across individuals that it can be used as an ‘epigenetic clock’ to predict an individual's chronological age to within a few years. Here, we examined how the pattern of epigenetic ageing in chimpanzees compares with humans. We profiled genome-wide blood methylation levels by microarray for 113 samples from 83 chimpanzees aged 1–58 years (26 chimpanzees were sampled at multiple ages during their lifespan). Many sites (greater than 65 000) showed significant change in methylation with age and around one-third (32%) of these overlap with sites showing significant age-related change in humans. At over 80% of sites showing age-related change in both species, chimpanzees displayed a significantly faster rate of age-related change in methylation than humans. We also built a chimpanzee-specific epigenetic clock that predicted age in our test dataset with a median absolute deviation from known age of only 2.4 years. However, our chimpanzee clock showed little overlap with previously constructed human clocks. Methylation at CpGs comprising our chimpanzee clock showed moderate heritability. Although the use of a human microarray for profiling chimpanzees biases our results towards regions with shared genomic sequence between the species, nevertheless, our results indicate that there is considerable conservation in epigenetic ageing between chimpanzees and humans, but also substantial divergence in both rate and genomic distribution of ageing-associated sites. This article is part of the theme issue ‘Evolution of the primate ageing process'.

It has been well known for ages that in living organisms the rhythmicity of biological processes is linked to the ~ 24-hour light–dark cycle. However, the exact function of the circadian clock system has been explored only in the past decades. It came to light that the photosensitive primary “master clock” is situated in the suprachiasmatic photosensitive nuclei of the special hypothalamic region, and that it is working according to ~24-hour changes of light and darkness. The master clock sends its messages to the peripheral “slave clocks”. In many organs, like pancreatic β-cells, the slave clocks have autonomic functions as well. Two essential components of the clock system are proteins encoded by the CLOCK and BMAL1 genes. CLOCK genes are in interaction with endonuclear receptors such as peroxisoma-proliferator activated receptors and Rev-erb-α, as well as with the hypothalamic-pituitary-adrenal axis, regulating the adaptation to stressors, energy supply, metabolic processes and cardiovascular system. Melatonin, the product of corpus pineale has a significant role in the functions of the clock system. The detailed discovery of the clock system has changed our previous knowledge about the development of many diseases. The most explored fields are hypertension, cardiovascular diseases, metabolic processes, mental disorders, cancers, sleep apnoe and joint disorders. CLOCK genes influence ageing as well. The recognition of the periodicity of biological processes makes the optimal dosing of certain drugs feasible. The more detailed discovery of the interaction of the clock system might further improve treatment and prevention of many disorders. Orv. Hetil., 2012, 153, 1370–1379.

Abstract Circadian rhythms are intrinsically generated 24 h rhythms that play a vital role in enabling the skin to adapt temporally to various external stimuli. These include ultraviolet radiation, physical trauma and water loss. At the molecular level, circadian clocks consist of various clock genes and proteins, including Per2/Cry1 and Bmal1/Clock, forming autoregulatory feedback loops. Although these rhythms are known to be impaired in ageing skin, there are limited therapeutic options to restore skin cell circadian function. As small peptides with homology to amino acid sequences found in extracellular matrix proteins (matrikines) can beneficially affect clinical and histological markers of skin ageing, in this study we characterized the ability of two novel tetrapeptides to influence the cellular circadian clocks of skin cells. HaCat keratinocytes transduced with a human Per2::luc promoter-driven reporter were used to monitor the effects of two synthetically generated peptides, GPKG and LSVD, on the cells’ intrinsic circadian clock. Following administration of these peptides at various concentrations (4–16 ppm), the oscillatory activity of the cells was amplified up to twofold vs. the vehicle control. LSVD was found to induce Per2::luc promoter activity significantly (P < 0.05). In addition to enhancing circadian rhythmicity, both peptides were assessed for their proliferative effect (by Incucyte imaging and MTT cell proliferation assays). At the higher concentrations tested, both GPKG and LSVD significantly increased proliferation in HaCat keratinocytes (P < 0.05). In conclusion, these peptides have been found to be highly effective in synchronizing the circadian clock in skin cells, leading to changes in their behaviour. This implies that these new peptides may have beneficial effects on skin cells, in part, by improving their circadian function. Given the findings of clock disruption in a number of diseases, as well as with age, identifying compounds that can reset the clock in skin cells is an important approach to developing treatments that can improve the functioning of cutaneous physiological processes that are under circadian control. Funding sources: this study was funded by the No. 7 Beauty Company.

It is well established that elderly individuals have increased difficulty sleeping at night combined with falling asleep and waking up earlier. Although these age-related declines in circadian output are clearly observable in activity recordings of laboratory animals, the underlying changes in molecular and neuronal activity remain unknown. The fruit fly, Drosophila melanogaster, has long been used as a model for studying the circadian system and for ageing research. In this thesis Drosophila was used as a model to study the effect of ageing on circadian and sleep behaviour. Circadian behaviour was measured using the Drosophila Activity Monitoring system, recording activity of flies at various stages of the ageing process, demonstrating a linear decline in rhythm strength with age combined with an increase in period length. Weakened circadian output is combined with significant alterations of diurnal behaviour of Drosophila, namely a reduction in morning and evening anticipatory behaviour. Ageing also has a significant impact on sleep behaviour, significantly increasing sleep duration whilst reducing latency, with larger effects observed on day- time sleep. Age-related changes in neuronal activity were investigated using whole-cell patch clamp electrophysiology to record from large lateral ventral (l-LNV) clock neurons, finding that ageing was associated with a significant decrease in input resistance, but no significant changes in spontaneous electrical activity or membrane potential. Manipulating the electrical properties of the circadian system by knocking down expression of candidate ion channels in all clock neurons had significant effects on behaviour, linking electrical activity with clock outputs. The results presented in this thesis demonstrate the suitability of Drosophila as a model to interrogate how ageing effects the circadian clock, identifying Alterations in the electrical properties of the l-LNV neurons may underlie observed changes in diurnal activity and sleep, while decreased remodelling of the s-LNV neurons can explain weakened circadian behaviour.

Ce travail avait pour objet d’étudier les propriétés d’horloge et de synchronisation de la peau, un modèle potentiel d’horloge périphérique. L’activité rythmique a été analysée par bioluminescence en temps réel, sur des explants de peau abdominale et des fibroblastes dermiques primaires, isolés à partir de rats transgéniques Per1-luciférase. Nous avons montré que des explants de peau présentent une activité rythmique soutenue en culture, indiquant une importante synchronisation interne dans le tissu. Cette synchronisation se manifeste au cours du développement post-natal à partir de 1 mois et augmente jusqu’à 6 mois, avant de décroître, laissant place à des rythmes altérés à l’âge de 2 ans. Nous avons aussi établi que les fibroblastes dermiques présentent la propriété de compensation thermique commune à toutes les horloges circadiennes, et qu’ils sont potentiellement synchronisables par la mélatonine puisque celle-ci augmente leur amplitude en culture. Nous avons aussi préparé un vecteur lentiviral exprimant le gène rapporteur luciférase sous le contrôle du promoteur du gène horloge Bmal1, un nouvel outil pour compléter l’étude des rythmes dans les cellules de la peau
This work aimed to investigate the skin as a potential model of peripheral clock by characterizing its rhythmic and synchronization properties. Circadian activity was examined in abdominal skin explants and fibroblasts derived from Per1-Luciferase transgenic rats by real-time recording of bioluminescence. First, the skin clock was characterized from early postnatal to old age. Low amplitude oscillations appeared at 1 month only and their robustness increased until 6 months. In 1-2 year-old rats, skin circadian rhythms showed decreasing amplitude and abnormal cycles. Primary fibroblasts derived from the skin at the same ages demonstrated similar pattern of clock activity. Temperature compensation, an intrinsic clock feature, was shown the first time in skin and primary fibroblasts. Secondly, we demonstrated a phase-dependent effect of melatonin to increase the amplitude of oscillations in skin primary fibroblasts, indicating it displays a synchronising role in the circadiansystem. Finally, to facilitate our studies on the multioscillatory skin tissue, we constructed a lentivirus carrying a Bmal1-luciferase reporter, to measure clock genes activities in human skin cells

The main topic of this thesis is the study of the interaction of agents interconnected in a large-scale network. In the thesis, three complementary problems have been afforded: Analysis of Consensus Networks, Synthesis of Higher Order Consensus Networks, and Application of Synchronization algorithms
Questa tesi di dottorato e incentrata sullo studio dell'interazione di agenti interconnessi in rete. In questa tesi vengono affrontati tre problemi complementari l'un l'altro: Analisi di reti di consenso, Sintesi di reti di consenso di ordine superiore, e Applicazione di algoritmi di sincronizzazione

Cette thèse a pour objectif l’élaboration de nanoparticules hybrides à base de silice par microémulsion inverse. Les nanoparticules de silice constituent une matrice de base permettant de confiner et de protéger des molécules organiques et/ou des nanoparticules métalliques. L’incorporation combinée de différentes entités dans la silice ouvre ainsi de larges perspectives de par l'introduction de nouvelles propriétés liées à la structure hybride. Afin d’élaborer de tels objets, nous avons utilisé des micelles inverses à base d'eau, de Triton X-100, d'hexanol et de cyclohexane comme milieu réactionnel. L’influence des conditions opératoires sur le contrôle de la taille des micelles inverses a d'abord été étudiée. Ces micelles inverses ont ensuite été mises à profit comme nanoréacteurs pour la synthèse de nanoparticules de silice par procédé sol-gel en utilisant les précurseurs alkoxysilanes adéquats. Nous avons regardé dans quelle mesure il était possible de contrôler la taille des nanoparticules de silice en fonction du pourcentage d’eau par rapport au tensioactif. Il a ainsi été possible d’accéder de façon reproductible à des nanoparticules avec de tailles variables, de 30 nm à 200 nm. Nous avons ensuite regardé qu'il était possible d'encapsuler au sein de cette matrice nanométrique des fluorophores et des nanoparticules d’or et d’argent de façon contrôlée. En vue d’assurer une bonne stabilisation colloïdale en solution, ces nanoparticules hybrides ont été fonctionnalisées d'une part par ajout d'un silane fonctionnel et d'autre part par click chemistry. Nous avons ainsi pu montrer qu’il est possible d’effectuer dans un même milieu micellaire l’ensemble des processus de fabrication de la nanoparticule hybride, de la matrice de silice à sa fonctionnalisation en passant par l’incorporation d’entités fonctionnelles. Cette méthode de synthèse séquentielle nous a ainsi permis de supprimer les étapes de purification et de redispersion qui peuvent s’avérer problématiques dans les procédés classiques. L’ensemble de ce travail a été mis à profit pour la conception d’un agent antibactérien à base de nanoparticules argent/silice capables d’empêcher la prolifération bactérienne grâce au relargage progressif des ions argent. Les tests effectués en solution comme sur le coton et le polyéthylène téréphtalate imprégnés montrent effectivement un caractère antibactérien certain de ces systèmes
This thesis aims at developing hybrid nanoparticles based on silica by reverse microemulsion. The silica nanoparticles are the basic matrix containing and protecting organic molecules and/or metallic nanoparticles. The combined incorporation of different entities within the silica opens wide prospects for the introduction of new properties related to the hybrid structure. To develop such objects, we used reverse micelles based on water, Triton X-100, hexanol and cyclohexan as reaction medium. The influence of operating conditions on the control of the size of reverse micelles was first studied. These micelles were then set to be used as nanoreactors for the synthesis of silica nanoparticles by sol-gel using suitable alkoxysilanes precursors. We monitored how it was possible to control the size of silica nanoparticles based on the water to surfactant ratio. It was thus possible to prepare in a reproducible way nanoparticles with sizes varying from 30 nm to 200 nm. We then investigated the possibility to encapsulate, in this nanoscaled matrix, fluorophores and nanoparticles of gold and silver in a controlled manner. To ensure a good colloidal stability in solution, these hybrid nanoparticles were, on the one hand, modified by adding a functional silane and, on the other hand, by click chemistry. We have thus shown that it is possible to perform, in a same micellar media, all of manufacturing process of the hybrid nanoparticle, from the silica matrix to its functionalization passing by the incorporation of functional entities. This method of sequential synthesis allowed us to bypass the purification and redispersion steps that can be problematic in the conventional methods. All this work has been extended to the design of an antibacterial agent based of silver/silica nanoparticles, capable of preventing bacterial growth through the gradual release of silver ions. Tests conducted in solution on the impregnated cotton and polyethylene terephtalate indeed show an interesting antibacterial character of these systems

SecA ATPase is a critical member of the Sec system, which is important in the translocation of membrane and secreted polypeptides/proteins in bacteria. Small molecule inhibitors can be very useful research tools as well as leads for future antimicrobial agent development. Based on previous virtual screening work, we optimized the structures of two hit compounds and obtained SecA ATPase inhibitors with IC50 in the single digit micromolar range. These represent the first low micromolar inhibitors of bacterial SecA and will be very useful for mechanistic studies. Post synthetic modification is an important and efficient way of DNA functionalization especially in DNA aptamer selection. In this research, the feasibility of norbornene (Neo) modified thymidine triphosphate incorporation was described. Besides, substituted tetrazines have been found to undergo facile inversed electron demand Diels-Alder reactions with "tunable" reaction rates. This finding paves the way to utilize tetrazine conjugation reactions for not only DNA but also other labeling work.

Cette thèse a pour objectif l'élaboration de nanoparticules hybrides à base de silice par microémulsion inverse. Les nanoparticules de silice constituent une matrice de base permettant de confiner et de protéger des molécules organiques et/ou des nanoparticules métalliques. L'incorporation combinée de différentes entités dans la silice ouvre ainsi de larges perspectives de par l'introduction de nouvelles propriétés liées à la structure hybride. Afin d'élaborer de tels objets, nous avons utilisé des micelles inverses à base d'eau, de Triton X-100, d'hexanol et de cyclohexane comme milieu réactionnel. L'influence des conditions opératoires sur le contrôle de la taille des micelles inverses a d'abord été étudiée. Ces micelles inverses ont ensuite été mises à profit comme nanoréacteurs pour la synthèse de nanoparticules de silice par procédé sol-gel en utilisant les précurseurs alkoxysilanes adéquats. Nous avons regardé dans quelle mesure il était possible de contrôler la taille des nanoparticules de silice en fonction du pourcentage d'eau par rapport au tensioactif. Il a ainsi été possible d'accéder de façon reproductible à des nanoparticules avec de tailles variables, de 30 nm à 200 nm. Nous avons ensuite regardé qu'il était possible d'encapsuler au sein de cette matrice nanométrique des fluorophores et des nanoparticules d'or et d'argent de façon contrôlée. En vue d'assurer une bonne stabilisation colloïdale en solution, ces nanoparticules hybrides ont été fonctionnalisées d'une part par ajout d'un silane fonctionnel et d'autre part par click chemistry. Nous avons ainsi pu montrer qu'il est possible d'effectuer dans un même milieu micellaire l'ensemble des processus de fabrication de la nanoparticule hybride, de la matrice de silice à sa fonctionnalisation en passant par l'incorporation d'entités fonctionnelles. Cette méthode de synthèse séquentielle nous a ainsi permis de supprimer les étapes de purification et de redispersion qui peuvent s'avérer problématiques dans les procédés classiques. L'ensemble de ce travail a été mis à profit pour la conception d'un agent antibactérien à base de nanoparticules argent/silice capables d'empêcher la prolifération bactérienne grâce au relargage progressif des ions argent. Les tests effectués en solution comme sur le coton et le polyéthylène téréphtalate imprégnés montrent effectivement un caractère antibactérien certain de ces systèmes.

This Master thesis deals with synchronization of sensor nodes in wireless sensor net. It is used event ordering by the implementation of logical clocks . Lamport's algorithm is used here for synchronization, which is trying to order events within the given system. The thesis also evaluates how appropriate this principle for synchronization is. The implementation has been carried out in agent-oriented language AgentSpeak on the Jason platform. Samson environment has been used and modified for observation of this synchronization's behaviour and testing purposes.

Tese de Doutoramento no âmbito do Programa Doutoral Interuniversitário em Envelhecimento e Doenças Crónicas, apresentada à Faculdade de Medicina da Universidade de Coimbra.
The Clock Drawing Test (CDT) is a popular neuropsychological instrument for the identification of cognitive decline, particularly Alzheimer’s disease (AD). The use of this test lacked specific validation studies for the Portuguese population, and that was the purpose of this project. The CDT showed good psychometric properties in all parameters assessed. The three selected scoring systems (Rouleau, Cahn and Babins) presented an adequate internal consistency, always higher for the Babins scoring system: α=.548 and α=.560 (Rouleau); α=.547 and α=.559 (Cahn); α=.883 and α=.901 (Babins). Interrater reliability was addressed in a subsample of 70 Mild Cognitive Impairment (MCI) patients and revealed a high correlation between two raters with opposite experience in neuropsychology. The analysis of construct validity of the CDT was conducted through exploratory and confirmatory factor analysis. The Rouleau and Cahn scoring systems presented a factorial structure of a single factor, while the Babins scoring system revealed a three factor structure: time-setting (representation of time), display characteristics (representation of numbers and global gestalt), and planning (clock face and correct placement of numbers). The scores according to the three factors were statistically different between the three groups, following an expected pattern: controls>MCI>AD. The CDT showed overall high convergent validity with the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), as well as good concurrent validity with specific measures of depression, psychopathology and functionality. The performance of controls and MCI patients on the CDT was also significantly correlated with frontal/executive, memory, attentional, visuoconstructive and language tasks, as well as with the different MoCA domains. The CDT was able to discriminate the most common types of degenerative dementia, particularly AD, Frontotemporal dementia, dementia with Lewy bodies (DLB), vascular dementia and Parkinson’s disease dementia. The presence of specific qualitative errors (conceptual deficit and stimulus-bound) confirmed its sensitivity for AD and DLB. Unfortunately, the discrimination between MCI patients and controls was in line with the tendency of international results, revealing a poor diagnostic accuracy for milder forms of cognitive impairment. Following an international recommendation, we analysed the association of the CDT with the MMSE. We developed adequate norms (according to age and education) and conducted a validation study for MCI and AD patients. Our results showed that the association of both scores significantly differentiated all groups with good to excellent diagnostic accuracy for AD (84 to 87%), although with lower values for MCI (64 to 67% for MCI). The study of the CDT was complemented with the correlation with biological variables and biomarkers of disease in MCI patients. By correlating CDT scores with regional cerebral blood flow (rCBF) measured by single-photon emission computed tomography (SPECT), we observed that the performance of MCI patients who later developed dementia correlated with brain perfusion median 3 years before the onset of dementia; also, stimulus-bound and conceptual deficit errors correlated with decreased rCBF in regions of interest for AD. On the other hand, the analysis of cerebrospinal fluid biomarkers showed that CDT scores correlated with Aβ42, an association that supports the value of the CDT as a state marker. The longitudinal assessment of these patients showed that the Babins scoring system was able to distinguish patients who converted from patients who remained stable, and was able to detect changes from baseline to follow-up in our sample. Also, future converters presented a higher rate of stimulus-bound and conceptual deficit errors at baseline, a result that was in line with our previous studies. The second part of this project focused on a preliminary approach to a biopsychosocial perspective. We presented the relevance of comprehensive geriatric assessment in dementia and developed a first validation study of the Biopsychosocial Assessment Method (Portuguese acronym MAB), an instrument created with the purpose of collecting multidimensional information about the individual. Such data may then be used for the development of a personalized intervention plan. The results with cognitively healthy population and clinical groups with cognitive impairment (MCI and mild AD) showed that the MAB has good psychometric properties. The MAB total score presented 93% sensitivity and 57% specificity for the identification of AD patients, while the score on the psychological area resulted in a diagnostic accuracy of 67% for MCI and 87% for AD. We concluded that the MAB is a valid instrument for use in clinical contexts and it is brief and easy to administer to healthy and cognitively impaired older patients.
O Teste do Desenho do Relógio (TDR) é um instrumento neuropsicológico popular para a identificação de défice cognitivo, particularmente Doença de Alzheimer (DA). A utilização deste teste carecia de estudos específicos de validação para a população portuguesa, sendo esse o objetivo deste projeto. O TDR apresentou boas propriedades psicométricas em todos os parâmetros avaliados. Os três sistemas de cotação utilizados (Rouleau, Cahn e Babins) apresentaram uma consistência interna adequada, sempre mais elevada no sistema de Babins: α=.548 e α=.560 (Rouleau); α=.547 e α=.559 (Cahn); α=.883 e α=.901 (Babins). O acordo intercotadores, analisado numa amostra de 70 doentes com Défice Cognitivo Ligeiro (DCL), revelou uma correlação elevada entre dois avaliadores com experiência oposta em neuropsicologia. A análise da validade de construto do TDR foi efetuada através da análise fatorial exploratória e confirmatória. Os sistemas de Rouleau e Cahn apresentaram uma estrutura de fator único, enquanto o sistema de Babins revelou uma estrutura de três fatores: marcação das horas (representação das horas), características do mostrador (representação dos números e gestalt global), e planeamento (mostrador do relógio e colocação correta dos números). As pontuações de acordo com os três fatores foram estatisticamente diferentes entre os três grupos analisados, seguindo um padrão expectável: controlos>DCL>DA. O TDR apresentou validade convergente com os resultados no Mini-Mental State Examination (MMSE) e Montreal Cognitive Assessment (MoCA), assim como uma boa validade concorrente com medidas específicas de depressão, psicopatologia e funcionalidade. O desempenho de controlos e doentes com DCL correlacionou-se igualmente com tarefas frontais/executivas, de memória, atenção, capacidade visuoespacial e linguagem, assim como com os diferentes domínios do MoCA. O TDR foi capaz de discriminar os tipos mais frequentes de demência, particularmente DA, Demência Frontotemporal, Demência com Corpos de Lewy (DCLewy), demência vascular e Doença de Parkinson com demência. A presença de erros qualitativos específicos (stimulus-bound e défice conceptual) confirmou a sensibilidade do TDR para DA e DCLewy. Contudo, a discriminação entre doentes com DCL e controlos seguiu a tendência da maioria dos estudos internacionais, com uma acuidade diagnóstica pobre para formas mais ligeiras de défice cognitivo. Seguindo recomendações internacionais, analisamos a potencialidade da associação entre o TDR e o MMSE. Desenvolvemos dados normativos (de acordo com idade e escolaridade) e realizamos um estudo de validação em doentes com DCL e DA. A associação destes dois resultados distinguiu significativamente todos os grupos, com uma acuidade diagnóstica boa a excelente para DA (84 a 87%), embora com valores mais modestos para DCL (64 a 67%). O estudo do TDR foi complementado com a correlação com variáveis biológicas e biomarcadores de doença em doentes com DCL. A correlação dos resultados do TDR com valores de perfusão sanguínea cerebral, determinada através de tomografia computorizada de emissão de fotão único (SPECT) mostrou que os resultados de doentes que desenvolveram demência se correlacionavam com alterações na perfusão cerebral em média 3 anos antes da conversão, e que os erros stimulus-bound e défice conceptual se correlacionavam com hipoperfusão em áreas de interesse de DA. Por outro lado, a análise de biomarcadores de líquido cefalorraquidiano demonstrou que os resultados no TDR se correlacionavam com os valores de Aβ42, uma associação que suporta o valor deste teste enquanto marcador de estado. A análise longitudinal destes doentes permitiu verificar que o sistema de Babins foi capaz de distinguir os doentes que converteram no futuro daqueles que permaneceram estáveis, e identificou mudanças da baseline para o follow-up. Os doentes que converteram apresentaram ainda taxas mais elevadas de erros stimulus-bound e défice conceptual na baseline, um resultado que está em linha com os estudos prévios. Numa segunda fase, fizemos uma abordagem preliminar à perspetiva de avaliação biopsicossocial. Apresentamos a temática da avaliação geriátrica global aplicada à demência e desenvolvemos um primeiro estudo de validação do Método de Avaliação Biopsicossocial (MAB), um instrumento que fornece informação multidimensional acerca do indivíduo, com vista ao desenvolvimento de um plano de intervenção personalizado. Os resultados com população cognitivamente saudável e grupos clínicos com defeito cognitivo (DCL e DA ligeira) demonstraram que o MAB tem boas propriedades psicométricas. A pontuação global apresentou 93% de sensibilidade e 57% de especificidade para a identificação de doentes com DA ligeira, enquanto a área psicológica demonstrou uma acuidade diagnóstica de 67% para DCL e 87% para DA. Concluímos que o MAB é um instrumento válido para uso em contextos clínicos, sendo breve e fácil de aplicar a população geriátrica, com ou sem défice cognitivo.

Funkcjonowanie centralnego zegara biologicznego ssaków jest dobrze udokumentowane. Przedmiotem dyskusji pozostaje jednak istnienie tego mechanizmu w narządach męskiego układu rozrodczego. Rytmiczna ekspresja genów oscylatora molekularnego (Per1, Per2, Cry1, Cry2, Bmal1, Clock) i cykliczne zmiany poziomu kodowanych przez nie białek stanowią jedno z podstawowych kryteriów wykorzystywanych do identyfikacji zegarów peryferycznych u zwierząt. Dodatkowo przypuszczać należy, że oscylator molekularny, potencjalnie zlokalizowany w narządach męskiego układu rozrodczego może regulować procesy fizjologiczne charakterystyczne dla tego układu takie jak rozwój komórek linii płciowej czy produkcja hormonów płciowych i metabolizm steroidów. Zaangażowane w regulacje tych procesów są min. receptor androgenowy, białko StAR warunkujące transport steroidów przez błony mitochondriów i tym samym produkcję testosteronu oraz aromataza- enzym odpowiedzialny za przekształcanie testosteronu w estrogeny. Dodatkowo istnieją dane literaturowe wskazujące na związki genów i białek zegara biologicznego z czynnikami odpowiedzialnymi za nowotworzenie. Także receptor androgenowy pełni istotną role w powstawaniu nowotworów męskiego układu rozrodczego. Procesem który może wpływać zarówno na funkcjonowanie oscylatora molekularnego jaki i procesy prowadzące do transformacji nowotworowej jest starzenie organizmu.Biorąc to pod uwagę, celem niniejszej rozprawy doktorskiej było ustalenie czy w narządach męskiego układu rozrodczego myszy 10, 60 i 105 tygodniowych oraz komórkach Leydiga (in vivo i in vitro) zachodzi rytmiczna ekspresja genów zegara biologicznego, genu receptora androgenowego i genów związanych z metabolizmem steroidów (geny Cyp19 i StAR) stosując metodę ilościowego pomiaru kopii transkryptów (qPCR).Celem było także zbadanie czy poziom białka receptora androgenowego zmienia się rytmicznie w ciągu doby na terenie jąder i komórek Leydiga (in vivo i in vitro) wykorzystując metody immunocytochemiczne i Western Blot. Wykorzystując testy ELISA zbadano dobowe zmiany poziomu testosteronu, 5α-dihydrotestosteronu i estradiolu w surowicy myszy 10, 60 i 105 tygodniowych.Wykazano rytmiczne zmiany genów zegara biologicznego, receptora androgenowego, aromatazy i genu StAR w większości narządów męskiego układu rozrodczego myszy i w komórkach Leydiga in vitro. Starzenie się zwierząt ma wpływ na ekspresję genów zegara biologicznego, receptora androgenowego, aromatazy i StAR. Poziom receptora androgenowego zmienia się cyklicznie w komórkach Leydiga in vitro, brak natomiast wyraźnego rytmu dobowych zmian w jądrach myszy w różnym wieku. W surowicy badanych myszy występują dobowe rytmy zmian stężeń badanych hormonów płciowych, których profile zmieniają się z wiekiem zwierząt.
The mammalian central biological (circadian) clock is a well-known and documented mechanism. However existence of clockwork mechanism in organs of male reproductive system still is under discussion. Rhythmic expression of core clock gens (Per1, Per2, Cry1, Cry2, Bmal1, Clock) and proteins is a one of immanent feature used to identify peripheral circadian clocks. Additionally it is likely that molecular circadian oscillator supposedly located in male reproductive system may regulate physiology of these organs affecting process like sperm maturation, hormone secretion and steroid metabolism. Crucial for proper functioning of these processes are many genes, enzymes and proteins including androgen receptor, StAR protein responsible for cholesterol trafficking across mitochondrial membrane and consequently testosterone production and aromatase- enzyme responsible for biosynthesis of estrogens from androgens. Moreover recent findings revealed also that pathways critical to tumorigenesis are linked with circadian system and role of androgen receptor in development of male reproductive system tumors is well established. Noteworthy, ageing is the process that links and affect both circadian clock mechanism and tumorigenesis.Taking all that into account, the aim of this doctoral dissertation was to verify using qPCR method whether rhythmic gene expression of molecular clock, androgen receptor, Cyp19 aromatase gene and StAR gene occurs in organs of male reproductive system of mice of different age (10, 60 and 105 weeks of age) as well as in Leydig cells in vitro. The aim of this study was also to determine using immunohistochemistry and Western Blots if level of androgen receptor varies rhythmically in cytoplasm and nucleus of Leydig cells (in vivo and in vitro). Moreover levels of testosterone, 5α-dihydrotestosterone and estradiol in serum of 10, 60 and 105 weeks old mice were assessed using ELISA tests.Results show rhythmic expression of molecular clock androgen receptor, aromatase and StAR genes is most of studied organs of male reproductive system as well as in Leydig cells in vitro. Moreover ageing affects expression of these genes in reproductive system of mice. Androgen receptor level changes rhythmically in cultured Leydig cells, but not in testis of mice of different age. Additionally concentrations of studied sex hormones in serum of mice of different age changed rhythmically during a day and profiles of this rhythms changed with age.

The probability that a user will click a search result depends both on its relevance and its position on the results page. The position based model explains this behavior by ascribing to every item an attraction probability, and to every position an examination probability. To be clicked, a result must be both attractive and examined. The probabilities of an item-position pair being clicked thus form the entries of a rank-1 matrix. We propose the learning problem of a Bernoulli rank-1 bandit where at each step, the learning agent chooses a pair of row and column arms, and receives the product of their Bernoulli-distributed values as a reward. This is a special case of the stochastic rank-1 bandit problem considered in recent work that proposed an elimination based algorithm Rank1Elim, and showed that Rank1Elim's regret scales linearly with the number of rows and columns on "benign" instances. These are the instances where the minimum of the average row and column rewards mu is bounded away from zero. The issue with Rank1Elim is that it fails to be competitive with straightforward bandit strategies as mu tends to 0. In this paper we propose Rank1ElimKL, which replaces the crude confidence intervals of Rank1Elim with confidence intervals based on Kullback-Leibler (KL) divergences. With the help of a novel result concerning the scaling of KL divergences we prove that with this change, our algorithm will be competitive no matter the value of mu. Experiments with synthetic data confirm that on benign instances the performance of Rank1ElimKL is significantly better than that of even Rank1Elim. Similarly, experiments with models derived from real-data confirm that the improvements are significant across the board, regardless of whether the data is benign or not.