L'étude in vivo de l'impact de la pression pulsée sur les capillaires cérébraux de souris

Plusieurs décennies de recherche ont permis de mieux comprendre les effets de l’athérosclérose sur le système cardiovasculaire, d’améliorer la prévention et de développer des traitements efficaces. Les effets de l’athéroslérose sur le cerveau demeurent toutefois mal compris même si le lien entre le fonctionnement cognitif et la santé du système vasculaire est maintenant bien établi. La venue de nouvelles méthodes d’imagerie telle la microscopie laser à 2-photons (TPLM) permet d’étudier l’impact de certaines maladies sur la microvasculature cérébrale en mesurant le flux sanguin dans des vaisseaux uniques situés dans des régions cérébrales millimétriques sous la surface. Les résultats des études in vitro peuvent dorénavant être corrélés à ceux obtenus in vivo. En premier lieu, ce mémoire revoit la théorie ayant permis le développement de la TPLM qui permet de prendre des mesures hémodynamiques in vivo dans des vaisseaux de très petits calibres tels des capillaires cérébraux de souris. Par la suite, son utilisation est décrite chez des souris anesthésiées afin de comparer les mesures d’hémodynamie cérébrale tels la vitesse des globules rouges, le flux de globules rouges, le flux sanguin cérébral, l’hématocrite sanguin et le diamètre des vaisseaux. Finalement, nous avons comparé les données hémodynamiques entre des souris de 3 mois normales (WT ; n=6) et des souris atteintes d’athérosclérose précoce (ATX ; n=6). Les résultats obtenus sur un nombre total de 209 capillaires (103 pour les souris WT et 106 pour les souris ATX) démontrent que les souris ATX possèdent une vitesse des globules rouges (+40%) plus grande, un flux de globule rouge plus grand (+12%) et un flux capillaire plus élevé (+14%) sans démontrer pour aucun de ces paramètres, une différence statistiquement significative. L’hématocrite moyen (35±4% vs 33±2% ; p=0.71) et le diamètre moyen des vaisseaux (4.88±0.22μm vs 4.86±0.20μm ; p=0.23) étaient également comparables. La vitesse des globules rouges a démontré une faible corrélation avec le diamètre des vaisseaux (r=0.39) et avec le flux de globules rouges/seconde (r=0.59). En conclusion, les travaux menés dans le cadre de ce mémoire de maîtrise permettent d'envisager, grâce aux nouvelles méthodes d’imagerie cérébrale telle la TPLM, une meilleure compréhension des mécanismes hémodynamiques sous-jacents à la microcirculation cérébrale. L’effet d’une pression pulsée augmentée, tel que proposée dans l’athérosclérose reste cependant à démontrer avec cette méthode d’imagerie.

Analysis of Protein Turnover by Quantitative SNAP-Based Pulse-Chase Imaging

Assessment of protein dynamics in living cells is crucial for understanding their biological properties and functions. The SNAP-tag, a self labeling suicide enzyme, presents a tool with unique features that can be adopted for determining protein dynamics in living cells. Here we present detailed protocols for the use of SNAP in fluorescent pulse-chase and quench-chase-pulse experiments. These time-slicing methods provide powerful tools to assay and quantify the fate and turnover rate of proteins of different ages. We cover advantages and pitfalls of SNAP-tagging in fixed- and live-cell studies and evaluate the recently developed fast-acting SNAPf variant. In addition, to facilitate the analysis of protein turnover datasets, we present an automated algorithm for spot recognition and quantification.

A Comprehensive Discussion of HMBC Pulse Sequences: 4. Establishing Two-Bond Correlations from HMBC and Related Experiments

The utility of the HMBC experiment for structure elucidation is unquestionable, but the nature of the coupling pathways leading to correlations in an HMBC experiment creates the potential for misinterpretation. This misinterpretation potential is intimately linked to the size of the long-range heteronuclear couplings involved, and may become troublesome in those cases of a particularly strong 2JCH correlation that might be mistaken for a 3JCH correlation or a 4JCH correlation of appreciable strength that could be mistaken for a weaker 3JCH correlation. To address these potential avenues of confusion, work from several laboratories has been focused on the development of what might be considered “coupling pathway edited” long-range heteronuclear correlation experiments that are derived from or related to the HMBC experiment. The first example of an effort to address the problems associated with correlation path length was seen in the heteronucleus-detected XCORFE experiment described by Reynolds and co-workers that predated the development of the HMBC experiment. Proton-detected analogs of the HMBC experiment intended to differentiate 2JCH correlations from nJCH correlations where n = 3, 4, include the 2J,3J-HMBC, HMBC-RELAY, H2BC, edited-HMBC, and HAT H2BC experiments. The principles underlying the critical components of each of these experiments are discussed and experimental verification of the results that can be obtained using model compounds are shown. This contribution concludes with a brief discussion of the 1,1-ADEQUATE experiments that provide an alternative means of identifying adjacent protonated and non-protonated carbon correlations by exploiting 1JCC correlations at natural abundance.

(Table 2) Delta 14C record of sediment core Pulse-32_SMB

The D14C of surface water dissolved inorganic carbon (DIC) in the Southern California Bight was compared to D14C as recorded by the sterols in Santa Monica and Santa Barbara Basin sediments. All of the C26, C27, C28, and C29 sterols as well as dinosterol had 14C concentrations equal to surface water DIC, indicating that all of the major sterols were derived from phytoplanktonic production. There is no detectable terrestrial component. Their tracer capability was confirmed by comparing the "bomb 14C"-derived change in surface water D14CDIC with the change in D14Csterol. The "prebomb" D14CDIC was -82 per mil, and prebomb sterols averaged -75±19 per mil. The D14C value in 1996 was +71 per mil. Eighteen measurements representing eight different sterols from the sediment-water interface of both Santa Monica and Santa Barbara Basins averaged +62±23 per mil. When three of these values were eliminated because of suspected contamination, the remaining data averaged +71 ±12 per mil. The entire compound class could serve as an excellent proxy for the 14C concentration of ocean surface waters.

Fast neutron pulse reactors and fast neutron critical assemblies : a literature search /

"Reactor Technology."

A semi-automated pulse-echo ultrasonic system for inspecting tires. Interim report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Analog computation with random pulse sequences.

Vita.

A display for demonstrating analog computations with random pulse sequences,

"Supported in part by the Office of Naval Research under Contract N000 14-67-A-0305-0007."

The process of pulse sintering /

"Contract AT-30-1-Gen-366."

Single-pulse shock tube studies of the kinetics of the reaction N + O [arrow right over arrow left (reversible reaction)] 2 NO between 2000-3000⁰ K,

At head of title: Combustion Dynamics Division, Air Force Office of Scientific Research, ARDC, Washington, D. C., File no. AF 18(600)-1332.

A study of nanosecond pulse techniques in radar transmission.

Stamped at head of title: RADC-TR-61-247.

The general practice of physic : extracted chiefly from the writings of the most celebrated practical physicians, and the Medical Essays, Transactions, Journels, and Literary Correspondence of the Learned Societies in Europe, to which is prefixed, an introduction, containing: The Distinction of Similar Diseases, The Use of the Non Naturals, An Account of the Pulse, The Consent of the Nervous Parts, and a Sketch of the Animal Oeconomy /

Mode of access: Internet.

The pulse of progress : including a sketch of Jewish history /

"List of books and articles by Ellsworth Huntington from which much of the material in this book has been drawn" : p. 321-324.

Pulse in verbal rhythm.

"Reprinted from Poet lore, June, 1905".

The general practice of physic : extracted chiefly from the writings of the most celebrated practical physicians, and the medical essays, transactions, journals, and literary correspondence of the learned societies in Europe : to which is prefixed, an introduction, containing the distinction of similar diseases, the use of the non-naturals, an account of the pulse, the consent of the nervous parts, and a sketch of the animal œconomy /

Mode of access: Internet.