Browsing by Author "Thomas, Sean C."

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The role of formate in combatting oxidative stress.
(2016-03-18) Thomas, Sean C.
As all aerobic organisms are exposed to oxidative stress, they are known to devise intricate mechanisms to counter reactive oxygen species (ROS). Metabolic networks contributing to the production of ketoacids are prominent in alleviating the oxidative burden. When glyoxylate detoxifies ROS, formate is the principal by-product generated. In this study the contribution of formate in enabling the survival of the microbe Pseudomonas fluorescens challenged by hydrogen peroxide (H2O2) has been elucidated. When grown in the presence of H2O2 (stressed culture), the levels of formate were higher in the spent fluid and the soluble cell-free extracts compared to the controls. Formate was subsequently utilized as a reducing factor to produce NADPH and succinate. The former is mediated by formate dehydrogenase (FDH-NADP), whose activity was enhanced in the stressed cells. Fumarate reductase (FRD) that catalyzes the conversion of fumarate into succinate was also markedly increased in the stressed cells. Metabolic adaptation is a pivotal tool in combatting oxidative stress. Formate, a by-product of glyoxylate- mediated detoxification of ROS is recuperated as a potent reductive fuel. It is becoming quite evident that this simple metabolite has other biological roles that have not been fully appreciated.
Understanding the neurophysiological representation patterns of non-verifiable mental action verbs: an ERP investigation
(Laurentian University of Sudbury, 2014-03-19) Thomas, Sean C.
Imaging has revealed that brain activation of verbs with verifiable products (‘throw, kick’) activate language areas as well as the motor cortex responsible for the performance of the action described. An exploratory comparison of eye related verbs with no verifiable products (‘observe’) to mouth related verbs with verifiable products (‘shout’) has revealed a similar activation pattern. Thus in order to further study mental action verbs with no verifiable products, the present two-part study used words that were suitable across two modalities (e.g. you can ‘perceive’ both through vision and audition) and compare them to themselves under differing contexts of auditory and visual verbs so as to eliminate any word characteristics differences, as well as explored the two modalities directly. The primary purpose was to delineate whether associative learning or the mirror systems theory might better account for the acquisition of this unique subclass of verbs. Results suggest that Mirror systems theory more likely accounts for the observed cognitive processing differences between the two verbs. Keywords: Verbs, language, Event-related potentials, abstract, associative learning theory, mirror systems theory.