La present tesi avalua els efectes de certs factors ambientals sobre la paraoxonasa1 (PON1), enzim antioxidant, possiblement protector enfront les malalties cardiovasculars, a través de dos estudis d'intervenció i un de transversal. En primer lloc, el tractament amb simvastatina dels pacients amb hipercolesterolèmia familiar, que presentaven una activitat paraoxonasa baixa, s'associava a un increment de l'activitat fins a valors similars als d'individus normolipèmics, independentment dels polimorfismes PON1-55 o PON1-192. En segon lloc, l'entrenament físic s'associava a un augment de l'activitat paraoxonasa en els individus QQ i una disminució de la mateixa en els portadors de l'al·lel R pel polimorfisme PON1-192. L'increment de l'activitat paraoxonasa immediatament després de l'exercici físic agut era seguit per una disminució subseqüent de l'activitat. La recuperació dels nivells basals d'activitat paraoxonasa a les 24h de l'exercici físic agut es donava en els individus QQ independentment del seu estat d'entrenament, i en els individus portadors de l'al·lel R només quan estan entrenats. En tercer lloc, el consum elevat d'àcid oleic comportava un augment de la concentració de c-HDL i de l'activitat paraoxonasa en els homes portadors dels genotips QR i RR del polimorfisme PON1-192, respectivament.Paraules claus: paraoxonasa, PON1, genotips, simvastatina, hipercolesterolèmia familiar, interacció gen-dieta, lipoproteïna d'alta densitat (HDL), exercici físic agut, entrenament físic, estrès oxidatiu, àcid oleic, oli d'oliva, peròxids lipídics, malaltia cardiovascular. / The present thesis evaluates some environmental factor effects on paraoxonase1 (PON1), an possibly protective against cardiovascular disease antioxidant enzyme, through two intervention studies and a cross-sectional one. First, treatment with simvastatin of the familial hypercholesterolemic patients, which had low paraoxonase activity, was associated with an increase in the activity to values similar to the normolipemic ones, regardless of the PON1-55 or PON1-192 polymorphisms. Second, Regular exercise was associated with an increase in PON1 activity in QQ subjects and with a decrease in R carriers. Increased PON1 activity immediately after a bout of exercise was subsequently followed by a decrease of activity. The recovery of the basal PON1 activity levels at 24 h was found in QQ subjects regardless of their training status and in trained R carriers, but not in untrained R carriers. Third, high oleic acid intake was associated with increased HDL cholesterol and PON1 activity levels only in men who were QR and RR of the PON1-192 polymorphism, respectively.

Aim: The purpose of this study was to investigate acute effects of physical exercise of different intensities on working memory. Method: Twelve young adults, 20-40 years, 8 males and 4 females passed the screening and participated in a randomized experimental crossover within-subject design study with three experimental conditions. Working memory was measured with n-back consisting of three difficulty levels.  Results: No significant interaction effect within subjects between the three different exercise intensity conditions for accuracy or response time was found. A significant main effect of time was detected for n-back response time, F(1,11)=40.2, p=<.001, reflecting an overall shorter response time after exercise compared to before, independent of exercise intensity condition. A two-way interaction effect on accuracy was found between n-back session 1 and 2 in the low fitness group.  Conclusions: The exercise intensity does not seem to matter for the improvement of working memory performance. However, participants response time was shown to be faster following any given exercise intensity.