We used functional Near-Infrared Spectroscopy (fNIRS) and a split ratio paradigm used to investigate the role and nature of prior knowledge in conceptual change in science. Sixteen participants, eight physicists and eight non-physicists were presented with two types of videos, Newtonian (two balls of unequal mass falling at the same rate) and Impetus (two balls of unequal mass, the larger one falling faster), to vary their exposure to plausible and implausible information. Whereas no increased neural activation was found in physicists, non-physicists showed recruitment in the frontopolar areas and DLPFC. Studies implicating these regions in integration and working memory support the notion that prior knowledge held by novices is flexible and context-dependent.

We used functional Near-Infrared Spectroscopy (fNIRS) and a split ratio paradigm used to investigate the role and nature of prior knowledge in conceptual change in science. Sixteen participants, eight physicists and eight non-physicists were presented with two types of videos, Newtonian (two balls of unequal mass falling at the same rate) and Impetus (two balls of unequal mass, the larger one falling faster), to vary their exposure to plausible and implausible information. Whereas no increased neural activation was found in physicists, non-physicists showed recruitment in the frontopolar areas and DLPFC. Studies implicating these regions in integration and working memory support the notion that prior knowledge held by novices is flexible and context-dependent.

A new Laser Induced Fluorescence Capillary Zone Electrophoresis (LIF-CZE) bioassay to detect and study the catalytic activity of the sulfur assimilating enzyme commonly found in E. coli species; alkanesulfonate monooxygenase (EC 1.14.14.5) is described for the first time. This technique enables the possibility for direct injection onto a capillary for detection without the need for pre-concentration of sample and with minimal sample preparative steps prior to analysis. In this bioassay, a group of Fischer based cyanine dyes and two Oxazine (Nile red) derivatives were designed for further optimization as key Vis-NIR fluorescent substrate. In developing this technique, the test dyes were first assessed for their photophysical properties, based on four criteria; (1) photostable (2) solvatochromism (3) binding affinity towards both the monooxygenase active site and serum albumin and (4) chemical stability in strong electric field strength. Applying key dye characterization procedures including; molar absorptivity determination, quantum yield determination, photostability, solvatochromism and protein interaction studies it was determined that the Fischer indolium cyanine dyes were most suitable for the method development. The data revealed that under the test conditions, reduced flavin, the oxidative monooxygenase catalytically specifically converts the alkylsulfonate substituted cyanine dyes to the corresponding aldehyde. This new bioassay has proven to be quick, portable, sensitive, reliable and the exhibit the possibility of ‘on-the-spot’ detection; advantages not readily realized with other commonly applied techniques such as PCR, SPR, ELISA and GC used to study bacterial sulfur assimilation processes. In addition, recent literature results proposed by other research groups developing similar techniques showed strong reliance on GC analyses. Those assays involve the use of low molecular weight straight chain non-emissive alkanesulfonate substrates. Once enzyme catalysis occurs the aldehyde is formed becomes rather volatile and requires complex and tedious headspace sampling for GC analyses. This feature limits the in vitro applicability and eliminated the possibility in vivo development. Our goal is to further develop, optimize and present this CZE based bioassay as a suitable alternative to the current trends in the field while creating a more robust and sensitive in vitro monooxygenase detection method with the possibilities of in vivo application.

Les technologies d'imagerie intravasculaire c’est à dire l’échographie endo-coronaire (IVUS)et la tomographie par cohérence optique (IV-OCT) sont des outils précieux pour aider audiagnostic de la plaque d’athérosclérose et guider les gestes thérapeutiques.Le chapitre 1 présente les inconvénients de la coronarographie dans la pratique clinique.Dans plusieurs circonstances, l’IVUS et l’OCT ont clairement une valeur supplémentaire quandils sont utilisés comme un outil diagnostique en cas d'ambiguïtés angiographiques. Nousavons récemment rapporté la première observation utilisant l’OCT pour décrire une dissectioncoronaire d'une branche septale perforante responsable d’un infarctus du myocarde.Le chapitre 2 porte sur la reproductibilité de I’OCT entre différents instituts concernant denombreux paramètres qualitatifs et quantitatifs de la plaque d'athérome. Le but de notre étudeétait d'étudier en plus de la reproductibilité inter- et intra-observateur, la variabilité inter-institutsde I’OCT concernant les mesures quantitatives et qualitatives et de la comparer à celle del’IVUS. Dans ce travail, nous avons observé que, dans la mesure de la surface de la lumièreendocoronaire, des diamètres minimum et maximum de cette même lumière endocoronaire,de la surface endo-luminale du stent, des diamètres minimum et maximum endo-luminaux dustent, par des analystes provenant de 2 laboratoires différents, la reproductibilité inter-institutsde I’OCT était nettement supérieure à celle de l’IVUS. Le Chapitre 3 présente 2 nouvelles technologies robustes d'imagerie intravasculaire hybridesdéveloppées dans le laboratoire du Professeur Guillermo J. Tearney: l’OCT couplée à laspectroscopie dans le proche infra-rouge (OFDI-NIRS) et l’OCT couplée à l’autofluorescencedans le proche infra-rouge (OFDI-NIRAF). Les premières procédures d’OFDI-NIRS chezl’homme sont prévues dans un avenir proche. Les premières procédures chez l’homme ontété réalisées chez 12 patients porteurs d’un angor stable entre Juillet 2014 et Janvier 2015.Les résultats de cette étude pilote ont montré que le signal d’autofluorescence recueilli(NIRAF) a été focalement trés élevé dans des endroits de la plaque d’athérome où la plupartdes phénotypes morphologiques en OCT d’une plaque à haut risque de rupture étaientévidents. Les substrats biochimiques de ce signal d’autofluorescence (NIRAF) sont encore àélucider. / Intravascular imaging technologies i.e. IVUS and IV-OCT are valuable tools for interventionguidance and diagnostic plaque imaging.Chapter 1 introduces the drawbacks of coronary angiography in the clinical practice. In severalcircumstances, IVUS and IV-OCT have clearly an additional value when they are used as adiagnosis tool in case of angiographic ambiguities. We recently reported the first observationusing IV-OCT to describe a coronary dissection of a septal perforating branch causing AMI.Chapter 2 focuses on the inter-institute reliability of IV-OCT to determine qualitative andquantitative parameters of atherosclerotic plaque. The purpose of our study was to investigatefurther inter- and intra-observer reproducibility, the inter-institute variability for IV-OCT (OFDI)quantitative and qualitative measurements vs. IVUS measurements using publishedconsensus document definitions. In our work, we observed that in the measurement of lumenCSA, maximum and minimum lumen diameters, stent CSA, maximum and minimum stentdiameters by analysts from 2 different laboratories, inter-institute reproducibility of OFDI wasfound to be more consistent than IVUS.Chapter 3 present 2 new robust hybrid intravascular imaging technologies developed in Dr.Tearney’s laboratory i.e. OFDI-NIRS and OFDI-NIRAF, which may offer supplementary criteriafor plaque vulnerability. First-in-human OFDI-NIRS imaging procedures are anticipated in thenear future. First-in-human OFDI-NIRAF imaging procedures have been performed in a firstpioneering series of 12 stable patients between July 2014 and January 2015. Findings of thispilot study showed that NIRAF was focally elevated in plaque locations where most high-riskmorphologic phenotypes were evident. The biochemical substrates of the NIRAF signal stillhave to be elucidated.