Optimizing counterparty credit risk portfolio by reducing exposure at default variance

Rahoitusyhti��t pit��v��t omaa p����omaa taseessa harvinaisen suuria markkinamuutoksia varten ja t��m��n p����oman m����r�� on ohjattu valvontaviranomaisten toimesta. Euroopassa Basel akordi antaa suuntaviivat n��ille s����d��ksille. 2007 vuoden finanssikriisin j��lkeen rahoitusyhti��t sek�� valvojat ovat olleet entist�� kiinnostuneempia p����oman riitt��vyydest��. Tutkimuksia riskist��, s����d��ksist�� ja p����omavaateen madaltamisesta on tehty aikaisemmin, mutta t��ss�� tutkimuksessa keskityt����n vaateen jatkuvan muutoksen suuruuteen. Tutkimus sis��lt���� hypoteettisen vastapuoliriski portfolion, jossa on mukana valuuttajohdannaisia. T��t�� portfoliota simuloidaan eri tavoin, jotta n��ht��isiin kuinka suuri vaikutus portfolion koostumuksella voi olla p����omavaateen varianssiin. Jos t��m�� muuttuja on merkitt��v��, pit��isik�� rahoitusyhti��iden yritt���� pienent���� muutosta, jotta yhti��iden varap����oman m����r���� voitaisiin alentaa? Tutkimuksessa on my��s haastateltu Suomen johtavia vastapuoliriski asiantuntijoita, jotta n��ht��isiin rahoitusalan oma n��kemys asian merkitt��vyydest��. Tutkimusmenetelmin�� toimivat haastattelut sek�� numeerinen analyysi hypoteettisella portfoliolla. Kaupat t��h��n vastapuoliriski portfolioon on luotu 14 vuoden ajalle ja se sis��lt���� ainoastaan valuuttajohdannaisia viidess�� eri valuutassa. Riski lasketaan markkina-arvo menetelm��ll��, joista lasketaan VaR-mallilla tulevaisuuden riski nettoutuksen kera. Portfolion rakennetta muutetaan simuloinneissa, jotta n��ht��isiin vaikutus tulevaisuuden riskeille, joita k��ytet����n edustamaan p����omavaateen m����r���� ja sen vaihtelua yli ajan. Portfolioiden riskej�� lasketaan my��s rasituskokeiden avulla, jotta tuloksista saataisiin mahdollisimman todenmukaisia. Analyyttinen osuus tutkimuksesta n��ytt���� sen, ett�� t��m��n kaltainen optimointi on suuresti riippuvainen alkuper��isest�� portfoliosta, jonka m����ritt���� yleisesti rahoitusyhti��n myyntistrategia. Yleisesti ottaen p����omavaateen varianssin muutos voi simuloinneissa olla melko suurta, varsinkin jos mukaan huomioidaan rasitus testit, puuttuvat tuotteet sek�� muut p����omavaateen laskentaan huomioitavat seikat. Haastatteluissa saatiin selville millainen optimointi voisi olla mahdollista todellisuudessa. Huomattiin my��s ett�� t��m��n kaltainen ajattelumalli on jo huomattu alalla ennest����n. Jon Gregory jopa mainitsi, ett�� jotkin rahoitusyhti��t ovat enemm��n kiinnostuneita muutosten pienent��misest�� kuin itse p����omavaateen suuruudesta. N��ytt����kin silt��, ett�� t��m��n aihepiiri vaatisi entist�� enemm��n tutkimusta, sill�� sit�� ei ennest����n viel�� ole, ja rahoitusyhti��t ovat jo alkaneet etsim����n uusia keinoja selvit��kseen rahoitusalalla, joka on yh�� entisest����n kilpailullisempi.

Influence of different sanitizers on food contaminant bacteria: effect of exposure temperature, contact time, and product concentration

The efficiency of four Sanitizers - peracetic acid, chlorhexidine, quaternary ammonium, and organic acids - was tested in this work using different bacteria recognized as a problem to meat industry, Salmonella sp., S. aureus, E. coli and L. monocytogenes. The effects of sanitizer concentration (0.2, 0.5, 0.6, 1.0, 1.1 and 1.4%), at different temperatures (10 and 45 ��C) and contact time (2, 10, 15, 18 and 25 minutes) were evaluated. Tests in an industrial plant were also carried out considering previously obtained results. In a general way, peracetic acid presented higher efficiencies using low concentration (0.2%) and contact time (2 minutes) at 10 ��C. The tests performed in industrial scale showed that peracetic acid presented a good performance in concentration and contact time lower than that suggested by the suppliers. The use of chlorhexidine and quaternary ammonium led to reasonable results at the indicated conditions, and organic acids were ineffective under concentration and contact time higher than those indicated by the suppliers in relation to Staphylococcus aureus. The results, in general, show that the choice for the most adequate sanitizer depends on the microorganism contaminant, the time available for sanitizer application, and also on the process cost.

Foreign exchange exposure management in a fuel procurement company operating in the commodity markets

Fluctuating commodity prices, foreign exchange rates and interest rates are causing changes in cash flows, market value and the companies��� profit. Most of the commodities are quoted in US dollar. Companies with non-dollar accounting face a double risk in the form of the commodity price risk and foreign exchange risk. The objective of this Master���s thesis is to find out how companies under commodity should manage foreign exchange exposure. The theoretical literature is based on foreign exchange risk, commodity risk and foreign exchange exposure management. The empirical research is done by using constructive modelling of a case company in the oil industry. The exposure is model with foreign exchange net cash flow and net working capital. First, the factors affecting foreign exchange exposure in case company are analyzed, then a model of foreign exchange exposure is created. Finally, the models are compared and the most suitable method is defined. According to the literature, foreign exchange exposure is the foreign exchange net cash flow. However, the results of the study show that foreign exchange risk can be managed also with net working capital. When the purchases, sales and storage are under foreign exchange risk, the best way to manage foreign exchange exposure is with combined net cash flow and net working capital method. The foreign exchange risk policy of the company defines the appropriate way to manage foreign exchange risk.

Changes in the magnitude and pattern of translocation of photoassimilated ��CO in soybean plants following an acute exposure to gamma radiation /

Young soybean plants (Glycine ~. L. cultivar Harosoy '63), grown under controlled conditions, were exposed to gamma radiation on a single occasion. One hour following exposure to 3,750 rads, the mature trifoliate leaf of the soybean plant was isolated in a closed system and permitted to photoassimilate approximately 1-5 pCi of 14C02 for 15 minutes. After an additional 45 minute-period, the plant was sacrificed and the magnitude of translocation and distribution pattern of 14C determined. In the non-irradiated plants 18~ of the total 14C recovered was outside the fed leaf blades and of this translocated 14c, 28~ was above the node of the fed leaf, 38~ in the stem below the node, 28~ in the roots and 7~ in the petiole. As well, in the irradiated plants, a smaller per cent (6~) of the total 14 C recovered was exported out of the source leaf blades. Of this translocated 14c , a smaller per cent (20~) was found in the apical region above the node of the source leaf and a higher per cent (45~) was recovered from the stem below the node and in the petiole (11~). The per cent of exported 14 C recovered from the root was unaffected by the radiation. Replacement of the shoot apex with 20 ppm IAA immediately following irradiation, only J partially increased the magnitude of translocation but did completely restore the pattern of distribution to that observed in the non-irradiated plants. From supplementary studies showing a radiationinduced reduction of photosynthetic rates in the source leaf and a reduction of the cumulative stem and leaf lengths in the apical sink region, the observed effects of radiation on the translocation process have been correlated to damage incurred by the source and sink regions. These data suggest that the reduction in the magnitude of translocation is the result of damage to both the source and sink regions rather than the phloem conducting tissue itself, whereas the change in the pattern of translocation is probably the result of a reduced rate of 14C-assimilate movement caused by a radiation-induced decrease of sink metabolism, especially the decrease in the metabolism of the apical sink.

The impact of wine closure and packaging type, and light and temperature exposure on the concentration of 3-alkyl-2 -methoxypyrazines and other key constituents of wine

3-alkyl-2-methoxypyrazines (MPs) are grape- and insect-derived odor-active compounds responsible for vegetative percepts that are detrimental to wine quality when elevated. This study tested both the effect of closure/packaging types and light/temperature storage conditions on MPs (isopropyl-, secbutyl-, and isobutyl-MP) in wine. An MP-emiched wine rapidly (after 140 hours) and significantly decreased in MP concentration after natural and synthetic cork contact (immersion of closures in wine). This decrease was greatest with synthetic closures (70% - 89% reduction) and secbutyl-MP. Subsequently storage trials tested the effects of commercial closure/packaging options (natural cork, agglomerate cork, synthetic corks, screwcaps and TetraPak�� cartons) on MPs in MP-emiched Riesling and Cabernet Franc over 18 months. Regardless of packaging, isobutyl-MP was the most altered from bottling. Notably, all MP levels tended to decrease to the greatest extent in TetraPak�� cartons (~34% for all MPs) and there was evidence of contribution ofisoproyl- and secbutyl-MP from cork-based closures (i.e. ~30% increase in secbutyl-MP after 6 months) or from an unidentified wine constituent. To test the effects of various light/temperature conditions (light exposed at ambient temperature in three different bottle hues, light excluded at ambient temperature and light excluded at a "cellar" temperature (14��C)), MP-emiched Riesling and Cabernet Franc were also analyzed for MP concentrations over 12 months. MPs did not vary consistently with light or temperature. Other odorants and physico-chemical properties were tested in all wines during storage trials and closely agree with previous literature. These results provide novel insights into MPs during ageing, interactions with packaging and storage conditions, and assist in the selection of storage conditions/packaging for optimal wine quality.

Transmission of West Nile virus in the Niagara Region among a population at risk for exposure

Background. West Nile Virus (WNV), a mosquito-borne flavivirus, is one of an increasing number of infectious diseases that have been emerging or re-emerging in the last two decades. Since the arrival ofWNV to Canada to present date, the Niagara Region has only reported 30 clinical cases, a small number compared to the hundreds reported in other regions of similar conditions. Moreover, the last reported human case in Niagara was in 2006. As it has been demonstrated that the majority of WNV infections are asymptomatic, the question remains whether the lack of clinical cases in Niagara truly reflects the lack of transmission to humans or if infections are still occurring but are mostly asymptomatic. Objectives. The general objective of this study was to establish whether or not active WNV transmission could be detected in a human population residing in Niagara for the 2007 transmission season. To fullfil this objective, a cross-sectional seroprevalence study was designed to investigate for the presence of anti-WNV antibodies in a sample of Mexican migrant agricultural workers employed in farms registered with the Seasonal Agricultural Workers Program (SAWP). Due to the Mexican origin of the study participants, three specific research objectives were proposed: a) determine the seroprevalence ofanti-WNV antibodies as well as anti-Dengue virus antibodies (a closely related virus prevalent in Mexico and likely to confound WNV serology); b) analyze risk factors associated with WNV and Dengue virus seropositivity; and c) assess the awareness of study participants about WNV infection as well as their understanding of the mode of transmission and clinical importance of the infection. Methodology: After obtaining ethics clearance from Brock University, farms were visited and workers invited to participate. Due to time constraints, only a small number of farms were enrolled with a resulting convenience and non-randomized study sample. Workers' demographic and epidemiological data were collected using a standardized questionnaire and blood samples were drawn to determine serum anti-WNV and anti- Dengue antibodies with a commercial ELISA. All positive samples were sent to the National Microbiology Laboratory in Winnipeg, Manitoba for confirmation with the Plaque Reduction Neutralization Test (PRNT). Data was analyzed with Stata 10.0. Antibody determinations were reported as seroprevalence proportions for both WNV and Dengue. Logistic regression was used to analyze risk factors that may be associated with seropositivity and awareness was reported as a proportion of the number of individuals possessing awareness over the total number of participants. Results and Discussion. In total 92 participants working in 5 farms completed the study. Using the commercial ELISA, seropositivity was as follows: 2.2% for WNV IgM, 20.7% for WNV IgG, and 17.1 % for Dengue IgG. Possible cross-reactivity was demonstrated in 15/20 (75.0%) samples that were positive for both WNV IgG and Dengue IgG. Confirmatory testing with the PRNT demonstrated that none of the WNV ELISA positive samples had antibodies to WNV but 13 samples tested positive for anti-Dengue antibodies (14.1 % Dengue sereoprevalence). The findings showed that the ELISA performance was very poor for assessing anti-WNV antibodies in individuals previously exposed to Dengue virus. However, the ELISA had better sensitivity and specificity for assessing anti-Dengue antibodies. Whereas statistical analysis could not be done for WNV seropositivity, as all samples were PRNT negative, logistic regression demonstrated several risk factors for Dengue exposure_ The first year coming to Canada appeared to be significantly associated with increased exposure to Dengue while lower socio-economic housing and the presence of a water basin in the yard in Mexico appeared to be significantly associated with a decreased exposure to Dengue_ These seemingly contradictory results illustrate that in mobile populations such as migrant workers, risk factors for exposure to Dengue are not easily identified and more research is needed. Assessing the awareness of WNV and its clinical importance showed that only 23% of participants had some knowledge of WNV, of which 76% knew that the infection was mosquito-borne and 47% recognized fever as a symptom. The identified lack of understanding and awareness was not surprising since WNV is not a visible disease in Mexico. Since WNV persists in an enzootic cycle in Niagara and the occurrence of future outbreaks is unpredictable, the agricultural workers remain at risk for transmission. Therefore it important they receive sufficient health education regarding WNV before leaving Mexico and during their stay in Canada. Conclusions. Human transmission of WNV could not be proven among the study participants even when due to their occupation they are at high risk for mosquito bites. The limitations of the study sample do not permit generalizable conclusions, however, the study findings are consistent with the absence of clinical cases in the Niagara Region, so it is likely that human transmission is indeed neglible or absent. As evidenced by our WNV serology results, PRNT must be utilized as a confirmatory test since false positivity occurs frequently. This is especially true when previous exposure to Dengue virus is likely.

Subliminal Exposure to Empathy Primes: A New Method to Reduce Intergroup Bias?

An abundant literature has demonstrated the benefits of empathy for intergroup relations (e.g., Batson, Chang, Orr, & Rowland, 2002). In addition, empathy has been identified as the mechanism by which various successful prejudice-reduction procedures impact attitudes and behaviour (e.g., Costello & Hodson, 2010). However, standard explicit techniques used in empathy-prejudice research have a number of potential limitations (e.g., resistance; McGregor, 1993). The present project explored an alternative technique, subliminally priming (i.e., outside of awareness) empathy-relevant terms (Study 1), or empathy itself (Study 2). Study 1 compared the effects of exposure to subliminal empathy-relevant primes (e.g., compassion) versus no priming and priming the opposite of empathy (e.g., indifference) on prejudice (i.e., negative attitudes), discrimination (i.e., resource allocation), and helping behaviour (i.e., willingness to empower, directly assist, or expect group change) towards immigrants. Relative to priming the opposite of empathy, participants exposed to primes of empathy-relevant constructs expressed less prejudice and were more willingness to empower immigrants. In addition, the effects were not moderated by individual differences in prejudice-relevant variables (i.e., Disgust Sensitivity, Intergroup Disgust-Sensitivity, Intergroup Anxiety, Social Dominance Orientation, Right-wing Authoritarianism). Study 2 considered a different target category (i.e., Blacks) and attempted to strengthen the effects found by comparing the impact of subliminal empathy primes (relative to no prime or subliminal primes of empathy paired with Blacks) on explicit prejudice towards marginalized groups and Blacks, willingness to help marginalized groups and Blacks, as well as implicit prejudice towards Blacks. In addition, Study 2 considered potential mechanisms for the predicted effects; specifically, general empathy, affective empathy towards Blacks, cognitive empathy towards Blacks, positive mood, and negative mood. Unfortunately, using subliminal empathy primes ���backfired���, such that exposure to subliminal empathy primes (relative to no prime) heightened prejudice towards marginalized groups and Blacks, and led to stronger expectations that marginalized groups and Blacks improve their own situation. However, exposure to subliminal primes pairing empathy with Blacks (relative to subliminal empathy primes alone) resulted in less prejudice towards marginalized groups and more willingness to directly assist Blacks, as expected. Interestingly, exposure to subliminal primes of empathy paired with Blacks (vs. empathy alone) resulted in more pro-White bias on the implicit prejudice measure. Study 2 did not find that the potential mediators measured explained the effects found. Overall, the results of the present project do not provide strong support for the use of subliminal empathy primes for improving intergroup relations. In fact, the results of Study 2 suggest that the use of subliminal empathy primes may even backfire. The implications for intergroup research on empathy and priming procedures generally are discussed.

Isoflavone exposure throughout suckling results in improved adult bone health in mice

Exposure to isoflavones (ISO), abundant in soy protein infant formula, for the first 5 days of life results in higher bone mineral density (BMD),greater trabecular connectivity and higher fracture load of lumbar vertebrae (LV) at adulthood. The effect of lengthening the duration of exposure to ISO on bone development has not been studied. This study determined if providing ISO for the first 21 days of life, which more closely mimics the duration that infants are fed soy protein formula, results in higher BMD, improved bone structure and greater strength in femurs and LV than a 5-day protocol. Female CD-1 mice were randomized to subcutaneous injections of ISO (7 Q1 mg kg/body weight/day) or corn oil from postnatal day 1 to 21. BMD, structure and strength were measured at the femur and LV at 4 months of age, representing young Q2 adulthood. At the LV, exposure to ISO resulted in higher (P,0.05) BMD, trabecular connectivity and fracture load compared with control (CON). Exposure to ISO also resulted in higher (P,0.05) whole femur BMD, higher (P,0.05) bone volume/total volume and Q3 lower (P,0.05) trabecular separation at the femur neck, as well as greater (P,0.05) fracture load at femur midpoint and femur neck compared with the CON group. Exposure to ISO throughout suckling has favorable effects on LV outcomes, and, unlike previous studies using 5-day exposure to ISO, femur outcomes are also improved. Duration of exposure should be considered when using the CD-1 mouse to model the effect of early life exposure of infants to ISO.

EARLY LIFE EXPOSURE TO GENISTEIN AND DAIDZEIN DISRUPTS STRUCTURAL DEVELOPMENT OF REPRODUCTIVE ORGANS IN FEMALE MICE

In mice, exposure to isoflavones (ISO), abundant in soy infant formula, during the first 5 d of life alters structural and functional development of reproductive organs. Effects of longer exposures are unknown. The study objective was to evaluate whether exposure to a combination of daidzein and genistein in the first 10 compared to 5 d of life results in greater adverse effects on ovarian and uterine structure in adult mice. Thirteen litters of 8���12 pups were cross-fostered and randomized to corn oil or ISO (2 mg daidzein + 5 mg genistein/kg body weight/d) for the first 5 or 10 d of life. The 10-d protocol mimicked the period when infants are fed soy protein formula (SPF) but avoids the time when suckling pups can consume the mother���s diet. Body and organ weights and histology of ovaries and uteri were analyzed. There were no differences in the ovary or uterus weight, number of ovarian follicles, number of multiple oocyte follicles, or percent of ovarian cysts with 5 or 10 d of ISO intervention compared to respective controls. The 10-d ISO group had higher body weights from 6 d to 4 mo. of age and a higher percent of hyperplasia in the oviduct than the respective control. Lower numbers of ovarian corpus lutea and a higher incidence of abnormal changes were reported in the uteri of both ISO groups compared to their respective controls. Five- and 10-d exposure to ISO had similar long-lasting adverse effects on the structures of ovaries and uterus in adult mice. Only the 10-d ISO exposure resulted in greater body weight gain at adulthood.

Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population-based case-control studies in Montreal.

Cancer du poumon associ�� �� l���exposition au nickel, au chrome VI et au cadmium dans le milieu de travail utilisant deux ��tudes populationnelles cas-t��moins �� Montr��al. Au d��but des ann��es 1990, le nickel, le chrome VI et le cadmium ont ��t�� class��s en tant qu���agents canc��rig��nes de classe 1 par le CIRC (Centre International de Recherche sur le Cancer). Cependant, les r��sultats des ��tudes ayant permis la classification de ces m��taux n���ont pas toujours ��t�� reproduits, et d���importantes questions demeurent quant aux effets de ces m��taux �� de faibles niveaux d���exposition. Un plus grand nombre de recherches empiriques est donc n��cessaire afin de r��affirmer la canc��rog��nicit�� de ces agents, et d���identifier les circonstances dans lesquelles ils peuvent ��tre n��fastes. L'objectif de cette ��tude ��tait d'explorer la relation entre l���exposition �� un des m��taux (soit le nickel, le chrome VI, ou le cadmium) et les risques subs��quents de d��velopper un cancer du poumon chez des travailleurs provenant de diff��rents milieux de travail qui sont expos��s �� ces m��taux �� de diff��rents degr��s. Deux ��tudes cas-t��moins de base populationnelle men��es �� Montr��al ont fourni les donn��es n��cessaires pour examiner la canc��rog��nicit�� de ces m��taux. La premi��re ��tude ��tait men��e entre 1979 et 1986 chez des hommes ��g��s de 35 �� 70 ans ayant un cancer dans l���un de 19 sites anatomiques de cancer s��lectionn��s. La seconde ��tude ��tait men��e entre 1996 et 2001 chez des hommes et des femmes ��g��s de 35 �� 75 ans, avec un diagnostic de tumeur maligne au poumon. Dans ces deux ��tudes, les cas ont ��t�� recens��s dans tous les h��pitaux de l'��le de Montr��al, tandis que les contr��les populationnels appari��s par ��ge et stratifi��s par sexe, ont ��t�� s��lectionn��s des listes ��lectorales. Une entrevue avec chaque sujet a permis d'obtenir un historique d'emploi d��taill�� ainsi que des informations pr��cises sur les facteurs de risques socio-��conomiques et personnels. Les descriptions de poste ont ��t�� ��valu��es par une ��quipe d'experts chimistes et hygi��nistes afin de d��terminer si le sujet a ��t�� expos�� �� chaque agent, et pour mesurer �� la fois la concentration et la dur��e de chaque exposition, ainsi que l���exposition cumulative tout au long de la vie de chaque participant. Pour d��terminer si une exposition �� l���un des trois m��taux en cause ��tait associ��e �� une augmentation de l'incidence du cancer du poumon, des donn��es ont ��t�� analys��es par r��gression logistique : des ajustements ont ��t�� effectu��s pour des facteurs de confusion pertinents incluant un historique d��taill�� du tabagisme. Des mesures cat��goriques d'exposition cumul��e ont ��t�� ��galement analys��es, ainsi que la modification des effets par le tabagisme. Les deux ��tudes ont ��t�� analys��es s��par��ment, puis par la suite combin��es afin d'augmenter la puissance statistique. Les niveaux d'exposition mesur��s dans cette population ne semblaient pas poser un exc��s de risque de cancer du poumon pour les travailleurs expos��s au chrome VI. Cependant, ceux qui ont ��t�� expos��s au nickel ont subi une augmentation significative du risque, et ce, quel que soit leur niveau d'exposition. Le risque de d��velopper un cancer du poumon suite �� une exposition au cadmium ��tait ��lev��, mais pas de mani��re significative. Pour chacun des trois m��taux, le risque de cancer du poumon ��tait tr��s ��lev�� parmi les non-fumeurs, mais pas parmi les fumeurs. L���effet combin�� du tabagisme et de l���exposition aux m��taux ��tait compatible avec un exc��s de risque additif. Cependant, les intervalles de confiance dans cette ��tude tendaient �� ��tre larges, et une faiblesse de puissance statistique peut limiter l���interpr��tation de certains r��sultats. Cette ��tude est unique dans la mesure o�� elle a fourni des preuves empiriques sur les risques de d��velopper le cancer du poumon li��s aux faibles niveaux d���exposition au nickel, au chrome VI, ou au cadmium provenant de divers contextes de travail. Dans la plupart des autres ��tudes, la majorit�� des expositions pertinentes n���ont pas ��t�� bien contr��l��es. �� l'inverse, cette ��tude a b��n��fici�� de la collecte et de la disponibilit�� d'information d��taill��e concernant le tabagisme et d���autres facteurs de risque. Les r��sultats de cette ��tude ont d'importantes cons��quences pour la sant�� publique, tant au niveau de la d��termination des risques pour les travailleurs actuellement expos��s �� ces m��taux, qu'au niveau de l�����valuation des risques pour la population en g��n��ral, elle-m��me expos��e �� ces m��taux par le biais de la pollution et de la fum��e de cigarette. Cette analyse contribuera fort probablement �� une r����valuation par le CIRC de la canc��rog��nicit�� de ces m��taux. L'exploration de la relation entre les risques de cancer du poumon et l'exposition au nickel, au chrome VI et au cadmium est donc opportune et pertinente.

Associations between Exposure to Socio-Cultural Influences in Proximal Environments and Weight Concerns among Urban-Dwelling Women

R��sum�� Les pr��occupations et comportements alimentaires entourant le poids sont omnipr��sentes chez les jeunes adolescentes et femmes qui habitent dans les cultures occidentales o�� les formes corporelles sont orient��es vers un id��al ultra-mince. L���objectif de cette ��tude est d���examiner si une plus grande exposition aux endroits faisant la promotion de la minceur est associ��e �� des pr��occupations pour le poids plus ��lev��es chez les femmes. Cette ��tude fait partie d���un projet intitul�� ��Social, cultural, and economic disparities and disordered eating: Understanding the contribution of neighbourhood and individual level factors�� (Gauvin, Steiger, & Brodeur, 2009). Un ��chantillon de 1288 femmes ��g��es entre 20 et 40 ans et r��sidant �� Montr��al depuis au moins 12 mois ont r��pondu �� un sondage t��l��phonique. Des r��gressions logistiques ont compar�� les femmes se situant dans le quintile le plus ��lev�� des pr��occupations de poids avec les femmes dans les autres quintiles en fonction de leur exposition 15 jours ou plus dans des endroits faisant la promotion de la minceur. De plus, une analyse de sensibilit�� a v��rifi�� si l���association demeurait significative �� d���autres niveaux d���exposition. Les facteurs confondants ont ��t�� contr��l��s statistiquement. Les r��sultats d��montrent qu���une fr��quentation d���au moins 15 jours par mois d���endroits faisant la promotion de la minceur est associ��e �� des pr��occupations plus ��lev��es pour le poids. Aussi, fr��quenter ces lieux entre 15 et 20 jours/mois est aussi associ�� �� des pr��occupations de poids ��lev��es. Des interventions de sant�� publique pourraient viser la diminution des pressions socioculturelles vers la minceur.

Evaluation of mitochondrial function in a model of developmental programming of hypertension associated with transient neonatal oxygen exposure

UNE EXPOSITION N��ONATALE �� L���OXYG��NE M��NE �� DES MODIFICATIONS DE LA FONCTION MITOCHONDRIALE CHEZ LE RAT ADULTE Introduction: L���exposition �� l���oxyg��ne (O2) des ratons nouveau-n��s a des cons��quences �� l�����ge adulte dont une hypertension art��rielle (HTA), une dysfonction vasculaire, une n��phrop��nie et des indices de stress oxydant. En consid��rant que les reins sont encore en d��veloppement actif lors des premiers jours apr��s la naissance chez les rats, jouent un r��le cl�� dans le d��veloppement de l���hypertension et qu���une dysfonction mitochondriale est associ�� �� une augmentation du stress oxydant, nous postulons que les conditions d��l��t��res n��onatales peuvent avoir un impact significatif au niveau r��nal sur la modulation de l���expression de prot��ines cl��s du fonctionnement mitochondrial et une production mitochondriale excessive d���esp��ces r��actives de l��� O2. M��thodes: Des ratons Sprague-Dawley sont expos��s �� 80% d���O2 (H) ou 21% O2 (Ctrl) du 3e au 10e jr de vie. En consid��rant que plusieurs organes des rats sont encore en d��veloppement actif �� la naissance, ces rongeurs sont un mod��le reconnu pour ��tudier les complications d���une hyperoxie n��onatale, comme celles li��es �� une naissance pr��matur��e chez l���homme. �� 4 et �� 16 semaines, les reins sont pr��lev��s et les mitochondries sont extraites suivant une m��thode d���extraction standard, avec un tampon contenant du sucrose 0.32 M et diff��rentes centrifugations. L���expression des prot��ines mitochondriales a ��t�� mesur��e par Western blot, tandis que la production d��� H202 et les activit��s des enzymes cl��s du cycle de Krebs ont ��t�� ��valu��es par spectrophotom��trie. Les r��sultats sont exprim��s par la moyenne �� SD. R��sultats: Les rats m��les H de 16 semaines (n=6) pr��sentent une activit�� de citrate synthase (consid��r�� standard interne de l���expression prot��ique et de l���abondance mitochondriales) augment��e (12.4 �� 8.4 vs 4.1 �� 0.5 ��mole/mL/min), une diminution de l���activit�� d���aconitase (enzyme sensible au redox mitochondrial) (0.11 �� 0.05 vs 0.20 �� 0.04 ��moles/min/mg mitochondrie), ainsi qu���une augmentation dans la production de H202 (7.0 �� 1.3 vs 5.4 �� 0.8 ��moles/mg prot��ines mitochondriales) comparativement au groupe Ctrl (n=6 m��les et 4 femelles). Le groupe H (vs Ctrl) pr��sente ��galement une diminution dans l���expression de peroxiredoxin-3 (Prx3) (H 0.61��0.06 vs. Ctrl 0.78��0.02 unit�� relative, -23%; p<0.05), une prot��ine impliqu��e dans l�����limination d��� H202, de l���expression du cytochrome C oxidase (Complexe IV) (H 1.02��0.04 vs. Ctrl 1.20��0.02 unit�� relative, -15%; p<0.05), une prot��ine de la chaine de respiration mitochondriale, tandis que l���expression de la prot��ine de d��couplage (uncoupling protein)-2 (UCP2), impliqu��e dans la dispersion du gradient proton, est significativement augment��e (H 1.05��0.02 vs. Ctrl 0.90��0.03 unit�� relative, +17%; p<0.05). Les femelles H (n=6) (vs Ctrl, n=6) de 16 semaines d��montrent une augmentation significative de l���activit�� de l���aconitase (0.33��0.03 vs 0.17��0.02 ��moles/min/mg mitochondrie), de l���expression de l���ATP synthase sous unit�� �� (H 0.73��0.02 vs. Ctrl 0.59��0.02 unit�� relative, +25%; p<0.05) et de l���expression de MnSOD (H 0.89��0.02 vs. Ctrl 0.74��0.03 unit�� relative, +20%; p<0.05) (superoxide dismutase mitochondriale, important antioxidant), tandis que l���expression de Prx3 est significativement r��duite (H 1.1��0.07 vs. Ctrl 0.85��0.01 unit�� relative, -24%; p<0.05). �� 4 semaines, les m��les H (vs Ctrl) pr��sentent une augmentation significative de l���expression de Prx3 (H 0.72��0.03 vs. Ctrl 0.56��0.04 unit�� relative, +31%; p<0.05) et les femelles pr��sentent une augmentation significative de l���expression d���UCP2 (H 1.22��0.05 vs. Ctrl 1.03��0.04 unit�� relative, +18%; p<0.05) et de l���expression de MnSOD (H 1.36��0.01 vs. 1.19��0.06 unit�� relative, +14%; p<0.05). Conclusions: Une exposition n��onatale �� l���O2 chez le rat adulte m��ne �� des indices de dysfonction mitochondriale dans les reins adultes, associ��e �� une augmentation dans la production d���esp��ces r��actives de l���oxyg��ne, sugg��rant que ces modifications mitochondriales pourraient jouer un r��le dans l���hypertension art��rielle et d���un stress oxydant, et par cons��quent, ��tre un facteur possible dans la progression vers des maladies cardiovasculaires. Mots-cl��s: Mitochondries, Reins, Hypertension, Oxyg��ne, Stress Oxydant, Programmation

The Hygiene Hypothesis and the risk of Crohn���s disease : a case-control study utilizing prospectively-collected exposure data from an administrative database

La maladie de Crohn (MC) p��diatrique a des cons��quences majeures sur la qualit�� de vie des patients atteints (troubles de croissance, absent��isme scolaire, etc). L�����tiologie de la MC est inconnue. La th��orie de l���hygi��ne (TH) stipule que les conditions de vie sanitaires des pays industrialis��s pr��viennent l���exposition antig��nique et emp��chent le d��veloppement de la tol��rance immunitaire chez les enfants. Ceci m��nerait �� une r��action excessive du syst��me immunitaire lors d���expositions subs��quentes et engendrerait le d��veloppement de maladies inflammatoires chroniques telles la MC. Objectif: Analyser l���association entre la fr��quence, la temporalit�� et le type d���infections infantiles (indicateurs d���environnements pourvus d���antig��nes) et le risque de MC p��diatrique. Une ��tude cas-t��moin f��t r��alis��e, les cas de MC provenant d���un centre hospitalier tertiaire montr��alais. Les t��moins, provenant des registres de la R��gie d���assurance maladie du Qu��bec (RAMQ), furent appari��s aux cas selon leur ��ge, sexe et lieu de r��sidence. L���exposition aux infections f��t d��termin��e gr��ce aux codes de diagnostic ICD-9 inscrits dans la base de donn��es de la RAMQ. Un mod��le de r��gression logistique conditionnelle f��t construit afin d���analyser l���association entre infections et MC. Des ratios de cotes (RC) et intervalles de confiance �� 95% (IC 95%) furent calcul��s. R��sultats: 409 cas et 1621 t��moins furent recrut��s. Les r��sultats de l���analyse sugg��rent un effet protecteur des infections infantiles sur le risque de MC (RC: 0,67 [IC: 0,48-0,93], p=0,018), plus particuli��rement au cours des 5 premi��res ann��es de vie (RC: 0.74 [IC: 0,57-0,96], p=0,025). Les infections r��nales et urinaires, ainsi que les infections des voies orales et du syst��me nerveux central (virale), semblent particuli��rement associ��es �� l���effet protecteur. Les r��sultats de l�����tude appuient la th��orie de l���hygi��ne: l���exposition aux infections infantiles pourrait r��duire le risque de MC p��diatrique.

Sunlight exposure and prostate cancer risk : a case-control study in Montreal, Canada

Objectifs: ��valuer l���association entre l���exposition r��cr��ative, professionnelle et globale au soleil et le risque de cancer de la prostate (CaP). M��thodes: Dans le contexte d���une ��tude cas-t��moins sur le CaP men��e �� Montr��al, Canada, des entrevues ont ��t�� compl��t��es aupr��s de 1371 cas incidents de CaP diagnostiqu��s en 2005-2009, et 1479 t��moins de la population g��n��rale. Des questionnaires d��taill��s ont permis d���obtenir de l���information sur la fr��quence et la dur��e de participation �� toute activit�� ext��rieure lors des loisirs durant l�����ge adulte, ainsi qu���une description de chaque emploi tenu au cours de la vie. Une matrice emploi-exposition canadienne a ��t�� appliqu��e �� chaque emploi afin d���assigner un niveau d���exposition professionnelle au soleil. Des indices cumulatifs de l���exposition au soleil bas��s sur le nombre d�����v��nements r��cr��atifs, la dur��e d���exposition professionnelle, ainsi qu���un indice d���exposition global ont ��t�� d��velopp��s. La r��gression logistique a ��t�� utilis��e pour estimer l���association entre chaque indice d���exposition et le CaP, en ajustant pour des variables de confusion potentielles. R��sultats: Globalement, il n���y avait pas d���association entre chacun des indices d���exposition et le risque de CaP. Certaines tendances en accord avec un risque l��g��rement plus faible chez les hommes expos��s au soleil ont ��t�� observ��es mais les r��sultats n�����taient pas statistiquement significatifs et il n���y avait pas de relation dose-r��ponse. Conclusion: Notre ��tude apporte peu de soutien �� l���hypoth��se d���une association entre l���exposition au soleil et le risque de d��velopper un cancer de la prostate.

Limited sampling strategies for estimation of cyclosporine exposure in pediatric hematopoietic stem cell transplant recipients : methodological improvement and introduction of sampling time deviation analysis.

Le suivi th��rapeutique est recommand�� pour l���ajustement de la dose des agents immunosuppresseurs. La pertinence de l���utilisation de la surface sous la courbe (SSC) comme biomarqueur dans l���exercice du suivi th��rapeutique de la cyclosporine (CsA) dans la transplantation des cellules souches h��matopo����tiques est soutenue par un nombre croissant d�����tudes. Cependant, pour des raisons intrins��ques �� la m��thode de calcul de la SSC, son utilisation en milieu clinique n���est pas pratique. Les strat��gies d�����chantillonnage limit��es, bas��es sur des approches de r��gression (R-LSS) ou des approches Bay��siennes (B-LSS), repr��sentent des alternatives pratiques pour une estimation satisfaisante de la SSC. Cependant, pour une application efficace de ces m��thodologies, leur conception doit accommoder la r��alit�� clinique, notamment en requ��rant un nombre minimal de concentrations ��chelonn��es sur une courte dur��e d�����chantillonnage. De plus, une attention particuli��re devrait ��tre accord��e �� assurer leur d��veloppement et validation ad��quates. Il est aussi important de mentionner que l���irr��gularit�� dans le temps de la collecte des ��chantillons sanguins peut avoir un impact non-n��gligeable sur la performance pr��dictive des R-LSS. Or, �� ce jour, cet impact n���a fait l���objet d���aucune ��tude. Cette th��se de doctorat se penche sur ces probl��matiques afin de permettre une estimation pr��cise et pratique de la SSC. Ces ��tudes ont ��t�� effectu��es dans le cadre de l���utilisation de la CsA chez des patients p��diatriques ayant subi une greffe de cellules souches h��matopo����tiques. D���abord, des approches de r��gression multiple ainsi que d���analyse pharmacocin��tique de population (Pop-PK) ont ��t�� utilis��es de fa��on constructive afin de d��velopper et de valider ad��quatement des LSS. Ensuite, plusieurs mod��les Pop-PK ont ��t�� ��valu��s, tout en gardant �� l���esprit leur utilisation pr��vue dans le contexte de l���estimation de la SSC. Aussi, la performance des B-LSS ciblant diff��rentes versions de SSC a ��galement ��t�� ��tudi��e. Enfin, l���impact des ��carts entre les temps d�����chantillonnage sanguins r��els et les temps nominaux planifi��s, sur la performance de pr��diction des R-LSS a ��t�� quantifi�� en utilisant une approche de simulation qui consid��re des sc��narios diversifi��s et r��alistes repr��sentant des erreurs potentielles dans la c��dule des ��chantillons sanguins. Ainsi, cette ��tude a d���abord conduit au d��veloppement de R-LSS et B-LSS ayant une performance clinique satisfaisante, et qui sont pratiques puisqu���elles impliquent 4 points d�����chantillonnage ou moins obtenus dans les 4 heures post-dose. Une fois l���analyse Pop-PK effectu��e, un mod��le structural �� deux compartiments avec un temps de d��lai a ��t�� retenu. Cependant, le mod��le final - notamment avec covariables - n���a pas am��lior�� la performance des B-LSS comparativement aux mod��les structuraux (sans covariables). En outre, nous avons d��montr�� que les B-LSS exhibent une meilleure performance pour la SSC d��riv��e des concentrations simul��es qui excluent les erreurs r��siduelles, que nous avons nomm��e �� underlying AUC ��, compar��e �� la SSC observ��e qui est directement calcul��e �� partir des concentrations mesur��es. Enfin, nos r��sultats ont prouv�� que l���irr��gularit�� des temps de la collecte des ��chantillons sanguins a un impact important sur la performance pr��dictive des R-LSS; cet impact est en fonction du nombre des ��chantillons requis, mais encore davantage en fonction de la dur��e du processus d�����chantillonnage impliqu��. Nous avons aussi mis en ��vidence que les erreurs d�����chantillonnage commises aux moments o�� la concentration change rapidement sont celles qui affectent le plus le pouvoir pr��dictif des R-LSS. Plus int��ressant, nous avons mis en exergue que m��me si diff��rentes R-LSS peuvent avoir des performances similaires lorsque bas��es sur des temps nominaux, leurs tol��rances aux erreurs des temps d�����chantillonnage peuvent largement diff��rer. En fait, une consid��ration ad��quate de l'impact de ces erreurs peut conduire �� une s��lection et une utilisation plus fiables des R-LSS. Par une investigation approfondie de diff��rents aspects sous-jacents aux strat��gies d�����chantillonnages limit��s, cette th��se a pu fournir des am��liorations m��thodologiques notables, et proposer de nouvelles voies pour assurer leur utilisation de fa��on fiable et inform��e, tout en favorisant leur ad��quation �� la pratique clinique.