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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.
11

An Examination of the Relationship of ABO Blood Group and Lifespan in a Hospitalized Population in the Southeastern United States

Moon, Tara 09 April 2014 (has links)
The clinical significance of ABO blood group is evident and universally accepted with regards to blood transfusion and pregnancy; however, the importance of ABO blood group as it relates to other diseases or disorders and overall mortality is not fully understood by the scientific community. Many studies have suggested associations between blood groups and disease, but consensus has not been reached regarding overall survival or longevity. This epidemiological, retrospective review of ABO blood group and age at the time of death in a hospitalized population in the Southeastern United States is the first multi-site study to examine this relationship. The study population was 56% male, 63.4% White, 31.0% Black and 2.1% Hispanic. Over half (61.1%) of the population had been transfused with red blood cells within one year of death. Overall, group O (46.6%) was the most prevalent ABO blood group, followed by group A (36.8%), Group B (12.9%) and group AB (3.7%). The population exhibited differences in the frequencies of ABO blood groups across the races, with the Hispanic population having the highest prevalence of group O (71.2%) and the Black and Asian populations having higher frequencies of group B (22.2% and 23.1% respectively) when compared to the overall population distribution. Lifespan ranged from 0 to 110 with a mean age at death of 58.7 years. While some differences in the mean age at death were noted across ABO blood groups, the main effect of ABO blood group on lifespan did not reach statistical significance when controlling for race, gender and history of red blood cell transfusion. These results contradict other studies that found an association between a particular ABO blood group and lifespan. Future work should consider including cause of death or primary disease as potential confounders and targeting expanded populations over a wider geographic area to increase generalizability and racial diversity.
12

Networks and the evolution of complex phenotypes in mammalian systems

Monzón Sandoval, Jimena January 2016 (has links)
During early development of the nervous system, gene expression patterns are known to vary widely depending on the specific developmental trajectories of different structures. Observable changes in gene expression profiles throughout development are determined by an underlying network of precise regulatory interactions between individual genes. Elucidating the organizing principles that shape this gene regulatory network is one of the central goals of developmental biology. Whether the developmental programme is the result of a dynamic driven by a fixed architecture of regulatory interactions, or alternatively, the result of waves of regulatory reorganization is not known. Here we contrast these two alternative models by examining existing expression data derived from the developing human brain in prenatal and postnatal stages. We reveal a sharp change in gene expression profiles at birth across brain areas. This sharp division between foetal and postnatal profiles is not the result of sudden changes in level of expression of existing gene networks. Instead we demonstrate that the perinatal transition is marked by the widespread regulatory rearrangement within and across existing gene clusters, leading to the emergence of new functional groups. This rearrangement is itself organized into discrete blocks of genes, each associated with a particular set of biological functions. Our results provide evidence of an acute modular reorganization of the regulatory architecture of the brain transcriptome occurring at birth, reflecting the reassembly of new functional associations required for the normal transition from prenatal to postnatal brain development.
13

Étude des rôles et des partenaires du domaine C terminal de Rpn11, une sous-unité du protéasome 26S, dans la dynamique mitochondriale chez Saccharomyces cerevisiae / Study of the roles and partners of the C-terminus domain of Rpn11, a proteasome 26S subunit, in the mitochondrial dynamics in Saccharomyces cerevisiae

Saunier, Rémy 18 December 2012 (has links)
Les mitochondries sont des organites semi autonomes, capables d’autoréplication, qui varient en nombre, en taille et en forme dans le cytoplasme de presque toutes les cellules eucaryotes. Elles sont notamment connues pour être les fournisseurs d’énergie de la cellule. Afin de mener à bien ce rôle, les mitochondries sont capables de fusionner et de se diviser, ce qui permet un contrôle de la forme du réseau mitochondrial. Le contrôle de ces évènements et la forme du réseau qui en résulte sont connus sous le nom de dynamique mitochondriale. Cette dynamique répond à de nombreux stimuli cellulaires et est très régulée. Récemment, il a été montré que le système ubiquitine-protéasome régule la fusion des mitochondries et qu’une des sous unités du protéasome contrôlait la fission des mitochondries. Le système ubiquitine-protéasome est un mécanisme qui repose sur plusieurs acteurs : les enzymes qui vont reconnaître les protéines cibles de ce système, une protéine appelée ubiquitine qui sert pour le marquage des protéines cibles et un complexe multi-protéique appelé protéasome effecteur de la dégradation des protéines cibles. Connu uniquement à l’origine pour son rôle dans la dégradation des protéines cibles, il est apparu dans les dernières années que le rôle de ce système ou de ses composants en dehors de ce système était bien plus vaste. Les études effectuées au laboratoire avaient déjà montré que Rpn11, une sous-unité du protéasome, régulait la fission des mitochondries indépendamment de l’activité protéolytique du protéasome. Le travail présenté ici porte sur le mécanisme d’action du domaine C-terminal de Rpn11 sur divers processus cellulaires tels que l’assemblage du protéasome, la régulation de la fission des mitochondries et des peroxysomes, la longévité cellulaire ou la formation de « Proteasome Storage Granule ». Ce manuscrit présente aussi le travail effectué pour trouver les partenaires qui permettent la régulation de la fission des mitochondries avec le domaine C-terminal de Rpn11 ainsi que l’étude de la localisation in vivo de Rpn11. / Mitochondria are semi-autonomous organelles, which size, shape and number vary in a wide range in almost every eukaryotic cell. They are famous to be the energy producer of the cells. For this purpose, mitochondria are able to fuse and divide. These events of fusion and fission are also known as the mitochondrial dynamic. This phenomenon is highly controlled and answers to many stimuli. Lately, it has been shown that the ubiquitin proteasome system controls the fusion of mitochondria and that a proteasome subunit controls the mitochondrial fission. The ubiquitin proteasome system is a mechanism that relies on many actors: enzymes recognizing the targets of this system, a protein called ubiquitin and a complex called proteasome in charge of the degradation of the targets. Primarily known for the protein degradation, many investigations suggest that this system has other roles. Our previous studies had already shown that the proteasome subunit named Rpn11 controls the fission of mitochondria independently of the proteolytic activities of the proteasome system. The work shown in this manuscript is focused on the mechanism of action of the C-terminus domain of Rpn11 on various cellular processes, including proteasome assembly, control of mitochondrial and peroxisomal fission, yeast lifespan and also the “Proteasome Storage Granule” formation. The in vivo localisation of Rpn11 and the elucidation of its partners on the mitochondrial fission regulation were also investigated.
14

A genome wide approach to stress response and chronological ageing in yeast

Cao, Lu January 2018 (has links)
Caloric restriction (CR) extends lifespan from yeast to mammals. In budding yeast, inhibition of the conserved TOR and/or PKA pathways has been shown to mediate lifespan extension by CR partly through the activation of stress response. However, how the stress response is regulated at the systems level is poorly understood. In this study, by using fluorescent reporters whose expression is dependent on the transcription factors Msn2/4 and Gis1, two separate screenings were conducted to reveal novel regulators of the stress response induced by starvation. A 'focused' screening on the 272 'signalling' mutants revealed that, apart from the previously identified Rim15, Yak1 and Mck1 kinases, the SNF1/AMPK complex, the cell wall integrity (CWI) pathway and a number of cell cycle regulators are necessary to elicit appropriate stress response. The chronological lifespan (CLS) of these signalling mutants correlates well with the amount of accumulated storage carbohydrates but poorly with transition-phase cell cycle status. Subsequent analyses reveal that the levels of intracellular reactive oxygen species are controlled by Rim15, Yak1 and Mck1. Furthermore, CLS extension enabled by tor1 deletion is dependent on the above three kinases. These data suggest that the signalling pathways (SNF1 and CWI) and the kinases downstream of TOR/PKA (Rim15, Yak1 and Mck1) coordinate the metabolic reprogramming (to accumulate storage carbohydrates) and the activation of anti-oxidant defence systems (to control ROS levels) to extend chronological lifespan. A 'genome-wide' screening of a haploid deletion library indicates that less than 10% of the non-essential genes are implicated in the regulation of starvation-induced stress response. Gene ontology analysis suggests that they can be grouped into major clusters including mitochondrial function, r-RNA processing, DNA damage and repair, transcription from RNA polymerase and cell cycle regulation. Further phenotypic assays confirm the previous observation that CLS extension is mostly correlated with the accumulation of storage carbohydrates. Compromised expression of stress response reporters is confirmed by FACS in a variety of mitochondrial mutants, suggesting that mitochondrial respiration also plays a key role in the activation of stress response. Put together, the above findings indicate that stress response and metabolic reprogramming induced by glucose starvation are coordinated by multiple signalling pathways and the activation of mitochondrial respiration is essential to both cellular processes and to CLS extension.
15

Formation and construction of a shock wave for 3-D compressible Euler equations with spherical initial data

Yin, Huicheng January 2002 (has links)
In this paper, the problem on formation and construction of a shock wave for three dimensional compressible Euler equations with the small perturbed spherical initial data is studied. If the given smooth initial data satisfies certain nondegenerate condition, then from the results in [20], we know that there exists a unique blowup point at the blowup time such that the first order derivates of smooth solution blow up meanwhile the solution itself is still continuous at the blowup point. From the blowup point, we construct a weak entropy solution which is not uniformly Lipschitz continuous on two sides of shock curve, moreover the strength of the constructed shock is zero at the blowup point and then gradually increases. Additionally, some detailed and precise estimates on the solution are obtained in the neighbourhood of the blowup point.
16

Drosophila CORL Phenotypes Connect Mating, Longevity, and Insulin Signaling

January 2018 (has links)
abstract: Drosophila CORL (dCORL) is a central nervous system (CNS)-specific gene that is hypothesized to function in Transforming Growth Factor β signaling. It is part of the Corl multigene family that includes mouse and human homologs. dCORL is necessary for Ecdysone Receptor isoform B1 (EcR-B1) protein expression in the mushroom body, a brain region responsible for learning and memory. Beyond this, dCORL function is unknown. As dCORL expression is restricted to the CNS, co-expression experiments were performed to identify dCORL-specific neurons. In these experiments, EcR-B1 protein expression was compared to dCORL mRNA expression revealing that they are not expressed in the same cells. Therefore, EcR-B1 is regulated non-autonomously by dCORL. Co-expression analyses were also conducted utilizing dCORL reporters. For example, the reporter AH-lacZ was co-stained with two pars intercerebralis (PI) markers: Drifter (Dfr; a transcription factor found in the nucleus) and Drosophila insulin-like peptide 2 (dILP2; a peptide present in the neurosecretory cells of the pars intercerebralis [PI].) The results showed that there was complete AH-lacZ co-expression with dILP2 in third instar larval and adult brains. Previous work in our lab on dCORL mutant (Df(4)dCORL) adult longevity showed a connection between mating and increased lifespan; mated mutant females had doubled lifespans compared to virgins. Given the published relationship between insulin and longevity, I hypothesized an association between insulin, dCORL, and mating. Df(4)dCORL mutants were used to analyze the effects of dCORL loss-of-function on dILP2. There was a reduction in the number of dILP2-expressing cells in mutants compared to wild type. In wild type larval and adult PI’s, most dILP2-positive neurons also expressed Dfr. Whereas in adult virgin mutants, all dILP2 neurons were Dfr-positive. Both 3-day and 15-day old mated females showed increased dILP2 cell numbers compared to virgin mutants. In these sets of dILP2 cells only a subset expressed Dfr as in wild type. The mutant phenotypes of mated flies showed partial rescue compared to virgins. This led to the conclusion there were associations between mating, longevity, and insulin signaling through dCORL. Homology between Drosophila and mammalian Corl proteins imply these connections may be seen in mammals. / Dissertation/Thesis / Masters Thesis Biology 2018
17

Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae) / Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae)

DRAG, Lukáš January 2011 (has links)
This Master Thesis brings results of study on endangered species Alpine Longhorn Rosalia alpina in beech forest of National Nature Reserve Maly and Velky Bezdez and Slatinne Hills. We used mark-recapture method to study the population size, longevity and dispersal ability of this species. We also assessed the distribution pattern of the species on another 15 habitat patches in the Ralska Upland.
18

Effects of Nictotinamide Riboside and Beta-Hydroxybutyrate on C. elegans Lifespan

Peters, Jeffery Dylan, Bradshaw, Patrick 12 April 2019 (has links)
The vitamin B3 precursor nicotinamide riboside (NR) and the ketone DL-body beta-hydroxybutyrate (BHB) are two of the most promising natural compounds yet identified for the treatment of aging and aging-related diseases. NR increases nicotinamide adenine dinucleotide (NAD) levels to activate sirtuin protein deacetylases and BHB is an anti-aging calorie restriction (CR) mimetic. Caenorhabditis elegans is a 1 mm long nematode worm used as a model system to study aging with a mean lifespan of roughly 2-3 weeks depending upon the exact temperature of culture. NR and BHB have previously been shown to increase lifespan when administered to C. elegans by roughly 20%. However, the effect on lifespan when both compounds are added together has not yet been studied. It is hypothesized that when added together the effect on lifespan will be slightly larger than when either compound is given alone, due to the activation of complementary signaling pathways. The results will help determine if humans could benefit from taking both compounds simultaneously as most signaling pathways that regulate lifespan are conserved from nematodes to humans. For these experiments cultures of mixed age C. elegans nematodes were first treated with alkaline-bleach to kill adult worms leaving only eggs that are protected by their thick eggshell. Using this protocol isolated eggs are age-synchronized to within 9 hours of each other. The eggs were then transferred into E. coli-permeable, but nematode impermeable 8 micron cell culture inserts placed in twelve well microplates with roughly 25-40 eggs per insert. 1.35 mL of liquid S-media containing 9 x109 E. coli cells/mL as food was added to each well. Microplates were shaken to provide culture aeration. After three days, the worms reached adulthood and 0.4 mM fluorodeoxyuridine (FUdR), a DNA synthesis inhibitor, was added to prevent C. elegans egg-laying to maintain age-synchrony. Every Monday, Wednesday, and Friday for the approximate 4 weeks of the lifespan experiments the worms were counted under a microscope and the culture media and bacteria replaced. Results were analyzed using Kaplan-Meier survival curves and Log-rank analysis. Results indicated that individual treatment with BHB or NR or both combined increased lifespan in the two trials performed thus far. Another trial is currently underway, and results will be analyzed after it is completed to determine if the combined treatment has a greater benefit on lifespan then either individual treatment. Future studies could also be performed to determine if either NR or BHB can further extend the lifespan of animals given rapamycin, a TOR kinase inhibitor, another promising anti-aging therapeutic.
19

Amino Acids in the Regulation of Aging and Aging-Related Diseases

Canfield, Clare Ann, Bradshaw, Patrick C. 01 January 2019 (has links)
Amino acids are the building blocks of protein, but also play important cellular signaling roles. The mechanisms through which altered levels of many amino acids are sensed and the signals transmitted are still largely unknown. Increasing evidence is showing that these signals may influence the aging process. In this regard, methionine restriction appears to be an evolutionary conserved mechanism to delay aging and supplementation with glycine can mimic methionine restriction to extend lifespan in rodents. Tryptophan restriction may also activate specific anti-aging pathways, but it could interfere with cognitive function. With exercise the consumption of dietary branched chain amino acids (BCAAs) may be beneficial in building muscle mass, but high levels of BCAAs as well as tyrosine and phenylalanine in the bloodstream are associated with metabolic disease such as insulin resistance. Individual supplementation or restriction of several different amino acids has shown promise in the treatment of insulin resistance in rodents. Much progress regarding the effects of amino acids on longevity has been made using yeast, nematodes, and fruit flies. Clearly, much more research is needed to understand the signaling pathways activated by amino acid imbalance before efficacious and well-tolerated dietary interventions can be developed for human aging and aging-related disorders. In this review the mechanisms through which altered dietary and cellular levels of the twenty proteogenic amino acids affect aging or aging-related disorders are discussed.
20

ADAPTING TO OBSTACLES: INHIBITION AND CREATIVE POTENTIAL IN A SAMPLE OF SUCCESSFULLY AGING OLDER ADULTS

Dinius, Cassandra 01 May 2020 (has links)
Studying older adults who are aging ‘successfully’ (i.e., avoiding disease/disability; maintaining high cognitive and physical functioning; engaging in meaningful interpersonal/social engagement) may offer insight into variables that contribute to cognitive change throughout the lifespan. Successful aging is related to levels of engagement, which may be promoted by the problem solving and reevaluation encouraged by the creative process (Fisher & Specht, 1999). Creative thinking requires the consideration of diverse concepts and strategies (e.g., generating many solutions), as well as the regulated filtering of these possibilities (e.g., neither too permissive nor too narrow when eliminating ideas; Baas, De Dreu, & Nijstad, 2011). Cognitive inhibition is necessary for goal-directed behavior, and may also promote creativity by influencing abilities such as plasticity and innovation. Performance on executive control tasks, especially those that draw on inhibition, are impacted by age. Performance on inhibitory (but not excitatory) tasks may be sensitive to arousal levels that fluctuate with circadian rhythm (synchrony effect). The current study examined performance on a variety of neuropsychological and creativity measures at two times of the day in a sample of successfully aging adults aged 70-79. Assessments of executive function, inhibition, and creativity (i.e., verbal and non-verbal divergent thinking) were administered to older adults twice, once at a time when inhibitory performance was expected to be ideal (synchronous) and another at a time when inhibitory performance was expected to be reduced (non-synchronous). We hypothesized that morning testing (synchronous) trials of inhibitory tasks would exhibit lower latency and error rates than evening testing (non-synchronous) trials; morning testing (synchronous) trials of creative potential tasks would exhibit lower fluency, flexibility, and originality scores than evening testing (non-synchronous) trials; and that Need For Cognition (NFC) scores and Information-Orientation ISI subscale scores would be positively correlated with overall (AM + PM) creativity scores (fluency, flexibility, originality). Participants were expected to demonstrate time of day effects on Stroop and TMT performance. Synchrony effects were not observed in this study. There was a significant relation between creative potential and Need for Cognition scores but not between creative potential and scores on the Information-Orientation subscale of the ISI. The current sample may have compensated with cognitive challenges such as those induced by testing time effects. These findings may suggest that a successfully-aging cohort is not impacted by synchrony effects. No previous research has used synchrony to compare aging trajectories (pathological, usual, successful) on cognitive performance. It is feasible that a successfully aging population would have significant cognitive reserve, brain reserve, or scaffolding strategies to compensate for the additional cognitive challenge of non-optimal testing time (Düzel, Schütze, Yonelinas, & Heinze, 2011; Reuter-Lorenz & Park, 2014). Indeed, a marker of successful aging is to compensate well with age-related changes and demonstrate minimal- to no- deficits in performance (Rowe & Kahn, 1997). Synchrony changes in cognitive performance may not be evident in a successfully aging population. The current study provides evidence that motivates intriguing questions about successful aging, inhibition, creativity, and time of day.

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