Doctor of Philosophy

dissertationSelenium is an essential trace element that has been linked to beneficial health effects in multiple disease states. These effects have been attributed to antioxidant activity of selenoproteins; proteins containing selenium incorporated as the amino acid selenocysteine during translation of the protein. Selenoprotein P is an extracellular glycoprotein containing multiple selenocysteine residues. It is the primary selenium distribution protein of the body as well as the major selenium containing protein in serum. An antioxidant function has been observed for this protein. The experiments presented in this dissertation were designed to further characterize the mechanisms of selenoprotein P regulation and function and test the hypothesis that mechanisms regulating the expression of selenoprotein P provide for modulation of this protein so it may function to provide antioxidant protection in extrahepatic tissues. When stimulated with ecdysone analogs, selenoprotein P expression was increased with the use of a fusion transcription factor that contains the glucocorticoid receptor DNA binding domain, an ecdysone ligand-binding domain, and a strong transactivation domain as well as the retinoid X receptor. In silico analysis of the selenoprotein P promoter identified putative glucocorticoid and retinoid responsive binding sites. Luciferase reporter assays and quantitative PCR were used to measure selenoprotein P transcription in engineered HEK-293 cells. The native glucocorticoid receptor inhibited selenoprotein P transactivation, and selenoprotein P was further attenuated in the presence of dexamethasone. These studies also aimed to determine if selenoprotein P possessed hydroperoxidase activity against lipid hydroperoxides generated from the metabolism of arachidonic acid by 15-lipoxygenase-1. Enzymatic reduction of 15- hydroperoxyeicosatetraenoic acid (15-HpETE) by selenoprotein P was observed in a NADPH-coupled biochemical assay. Diphenylpyrenylphosphin was used to measure lipid hydroperoxides in human embryonic kidney cells treated with selenoprotein P following exposure to 15-HpETE. Cellular oxidation increased with 15-HpETE treatment and selenoprotein P reduced this effect. These results suggest that selenoprotein P can function as an antioxidant enzyme during inflammation. An increased understanding of the mechanisms regulating selenoprotein P expression and activity could provide insight into the way in which selenium exerts its physiological effects

Does aging affect the immune status? A comparative analysis in 300 healthy volunteers from France, Austria and Spain

Background: As the European population is getting older, there is growing need in scientific data on how to achieve healthy and successful aging. A decline in immune function with age is unanimously supported by many epidemiological and clinical observations, with a decrease in T-cell mediated function encompassing a large part of this alteration. In the EU-funded VITAGE project, the effects of aging on biomarkers of immune status are being studied in three European countries. According to strict inclusion/exclusion criteria, a cohort of 300 healthy male non-smoking 20-75 years old volunteers were enrolled in France (n = 99), Spain (n = 100) and Austria (n = 101). In each country, the volunteers were classified as a function of age (one age group per decade). Biomarkers of immune status were determined including delayed-type hypersensitivity tests, measurement of lymphocyte surface markers, and serum determinations of interleukin-2, complement fractions and immunoglobulins. [br/] Results: There were moderate differences in the biomarkers of immune status of the VITAGE study volunteers among the three European centres. The percentage of Natural Killer (NK) cells was 156% and 142% higher in Spain as compared to France and Austria, respectively (p < 0.0001), and this increase was observed at any age group above 30 years. Comparison between age-groups showed that in Spain, but not in France or Austria, older individuals had significantly a lower B lymphocyte distribution and conversely, a higher NK cell distribution. Moreover, the CD4/CD8 ratio was positively correlated with age in Austrian subjects (p < 0.0001). [br/] Conclusion: Our results provide evidence of an increased NK cell distribution in the elderly, especially in the Spanish population. NK cell status may predict morbidity and mortality in the elderly, emphasizing the importance of innate as well as adaptive immunity in ensuring healthy longevity and cancer resistance, possibly in link with the Mediterranean diet

Epinephrine and dDAVP administration in patients with congenital nephrogenic diabetes insipidus Evidence for a pre-cyclic AMP V2 receptor defective mechanism

Epinephrine and dDAVP administration in patients with congenital nephrogenic diabetes insipidus. Evidence for a pre-cyclic AMP V2 receptor defective mechanism. We recently showed that the administration of the antidiuretic V2 specific agonist, l-desamino[8-D-arginine]vasopressin (dDAVP), to seven male patients with congenital nephrogenic diabetes insipidus (CNDI) did not cause a decrease in blood pressure nor an increase in plasma renin activity or factor VIIIc or von Willebrand factor release. In normal subjects, plasma renin activity, coagulation factors and plasma cyclic AMP are stimulated not only by dDAVP but also by the administration of epinephrine. In the present study, we measured tissue plasminogen activator (activity and antigenicity), von Willebrand factor multimers, plasma and urinary cyclic AMP concentrations following dDAVP or epinephrine administration. We infused epinephrine into three male patients with CNDI. Factor VIIIc and tissue plasminogen activator augmented by 75 to 100% and von Willebrand Factor multimers were increased; plasma renin activity and plasma cyclic AMP concentration increased by 200%. None of these values changed when the same subjects as well as eleven other male patients with CNDI received dDAVP. Furthermore, dDAVP administration increased plasma cyclic AMP concentrations in normal subjects, but not in 14 male patients with CNDI. These results demonstrate the specificity of the extrarenal V2 receptor defect expressed in our patients. The lack of a plasma cyclic AMP response to the administration of dDAVP would suggest an altered pre-cyclic AMP stimulation mechanism

Large enhancement of deuteron polarization with frequency modulated microwaves

We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar files in poltar.uu, which also brings cernart.sty and crna12.sty files neede

Processing and preservation methods of Wagashi Gassirè, a traditional cheese produced in Benin

peer reviewe

Spin Structure of the Proton from Polarized Inclusive Deep-Inelastic Muon-Proton Scattering

We have measured the spin-dependent structure function $g_1^p$ in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range $0.003 < x < 0.7$ and $1 GeV^2 < Q^2 < 60 GeV^2$. A next-to-leading order QCD analysis is used to evolve the measured $g_1^p(x,Q^2)$ to a fixed $Q^2_0$. The first moment of $g_1^p$ at $Q^2_0 = 10 GeV^2$ is $\Gamma^p = 0.136\pm 0.013(stat.) \pm 0.009(syst.)\pm 0.005(evol.)$. This result is below the prediction of the Ellis-Jaffe sum rule by more than two standard deviations. The singlet axial charge $a_0$ is found to be $0.28 \pm 0.16$. In the Adler-Bardeen factorization scheme, $\Delta g \simeq 2$ is required to bring $\Delta \Sigma$ in agreement with the Quark-Parton Model. A combined analysis of all available proton and deuteron data confirms the Bjorken sum rule.Comment: 33 pages, 22 figures, uses ReVTex and smc.sty. submitted to Physical Review

Subcellular distribution of human RDM1 protein isoforms and their nucleolar accumulation in response to heat shock and proteotoxic stress

The RDM1 gene encodes a RNA recognition motif (RRM)-containing protein involved in the cellular response to the anti-cancer drug cisplatin in vertebrates. We previously reported a cDNA encoding the full-length human RDM1 protein. Here, we describe the identification of 11 human cDNAs encoding RDM1 protein isoforms. This repertoire is generated by alternative pre-mRNA splicing and differential usage of two translational start sites, resulting in proteins with long or short N-terminus and a great diversity in the exonic composition of their C-terminus. By using tagged proteins and fluorescent microscopy, we examined the subcellular distribution of full-length RDM1 (renamed RDM1α), and other RDM1 isoforms. We show that RDM1α undergoes subcellular redistribution and nucleolar accumulation in response to proteotoxic stress and mild heat shock. In unstressed cells, the long N-terminal isoforms displayed distinct subcellular distribution patterns, ranging from a predominantly cytoplasmic to almost exclusive nuclear localization, suggesting functional differences among the RDM1 proteins. However, all isoforms underwent stress-induced nucleolar accumulation. We identified nuclear and nucleolar localization determinants as well as domains conferring cytoplasmic retention to the RDM1 proteins. Finally, RDM1 null chicken DT40 cells displayed an increased sensitivity to heat shock, compared to wild-type (wt) cells, suggesting a function for RDM1 in the heat-shock response

Individual, social, environmental, and physical environmental correlates with physical activity among Canadians: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>The identification of various individual, social and physical environmental factors affecting physical activity (PA) behavior in Canada can help in the development of more tailored intervention strategies for promoting higher PA levels in Canada. This study examined the influences of various individual, social and physical environmental factors on PA participation by gender, age and socioeconomic status, using data from the 2002 nationwide survey of the Physical Activity Monitor.</p> <p>Methods</p> <p>In 2002, 5,167 Canadians aged 15–79 years, selected by random-digit dialling from household-based telephone exchanges, completed a telephone survey. The short version of the International Physical Activity Questionnaire was used to collect information on total physical activity. The effects of socio-economical status, self-rated health, self-efficacy, intention, perceived barriers to PA, health benefits of PA, social support, and facility availability on PA level were examined by multiple logistic regression analyses.</p> <p>Results</p> <p>Self-efficacy and intention were the strongest correlates and had the greatest effect on PA. Family income, self-rated health and perceived barriers were also consistently associated with PA. The effects of the perceived health benefits, education and family income were more salient to older people, whereas the influence of education was more important to women and the influence of perceived barriers was more salient to women and younger people. Facility availability was more strongly associated with PA among people with a university degree than among people with a lower education level. However, social support was not significantly related to PA in any subgroup.</p> <p>Conclusion</p> <p>This study suggests that PA promotion strategies should be tailored to enhance people's confidence to engage in PA, motivate people to be more active, educate people on PA's health benefits and reduce barriers, as well as target different factors for men and women and for differing socio-economic and demographic groups.</p