Le travail de cette thèse a consisté à concevoir, réaliser et optimiser un montage expérimental de Polarisation Dynamique Nucléaire multi-échantillons pour des applications biomédicales en Imagerie Spectroscopique par Résonance Magnétique. Ce montage est constitué d'un aimant à fort champ magnétique (3,35T), dans lequel se place un système cryogénique à bain d'hélium (He4) liquide pompé pouvant atteindre des températures inférieures à 1,2K. Un ensemble d'inserts permet d'effectuer les différentes étapes du processus PDN dont l'irradiation des échantillons par un champ micro-onde (f=94GHz et P=50mW) et le suivi de leur polarisation par Résonance Magnétique Nucléaire. Ce système permet de polariser jusqu'à trois échantillons, de volume proche de 1mL, à des taux de polarisation de quelques pourcents. Il présente une forte autonomie supérieure à quatre heures, autorisant ainsi la polarisation de molécules à longues constantes de temps de polarisation. La possibilité de disposer quasi-simultanément, après dissolution, de plusieurs échantillons fortement polarisés ouvre la voie à de nouvelles applications dans le domaine de l'imagerie biomédicale / The aim of this thesis work was to design, build and optimize a large volume multisamples DNP (Dynamic Nuclear Polarization) polarizer dedicated to Magnetic Resonance Spectroscopic Imaging applications. The experimental system is made up of a high magnetic field magnet (3,35T) in which takes place a cryogenic system with a pumped bath of liquid helium (4He) allowing temperatures lower than 1,2K. A set of inserts is used for the different steps of DNP : irradiation of the sample by a microwave field (f=94GHz and P=50mW), polarization measurement by Nuclear Magnetic Resonance. . . With this system, up to three samples of 1mL volume can be polarized to a rate of few percents. The system has a long autonomy of four hours, so it can be used for polarizing molecules with a long time constant of polarization. Finally, the possibility to get quasisimultaneously, after dissolution, several samples with a high rate of polarization opens the way of new applications in biomedical imaging

La mesure de couplage dipolaire permet d’accéder à la structure tridimensionnelle d’un composé solide. Cependant, en présence d’une forte densité de spins couplés, le phénomène de troncature dipolaire rend difficile l’obtention de ces informations par RMN du solide. Ce problème peut être affranchi par l’étude de spins rares en abondance naturelle. En effet, avec une abondance naturelle de 1.1 %, la probabilité que trois 13C soient couplés, et avec elle la troncature dipolaire, devient négligeable. Une méthodologie basée sur la séquence de recouplage dipolaire POST-C7 permet d’accéder à des informations structurales d’échantillons en abondance naturelle sensibles à la fois à la conformation moléculaire et à l’empilement cristallin par mesure de couplages dipolaires 13C-13C. La sensibilité de détection des signaux RMN 13C est augmentée à l’aide la polarisation dynamique nucléaire ce qui permet de réduire considérablement les temps d’expériences. De plus, la séquence de recouplage R20_9_2 aidée de supercycles s’est montrée être plus robustes que POST-C7 face à de fortes anisotropies de déplacement chimique ou de forts couplages hétéronucléaires 1H-13C. La seconde problématique abordée concerne l’attribution de signaux 13C. En effet, il existe seulement quelques exemples de détermination de connectivités 13C -13C en abondance naturelle. Nous montrons ici que des spectres de corrélations dipolaires 13C-13C peuvent être obtenus en quelques jours à l’aide de la séquence de recouplage R20_9_2. Contrairement aux méthodologies basées sur le couplage J, notre séquence requiert un temps d’excitation DQ plus court ce qui la rend adaptée à l’étude de solides désordonnés. / Measurment of dipolar coupling provides 3D structural information of powder samples. However, in practice, the high density of spins in organic compounds prevents the measurements of long-range dipolar couplings in solid-state NMR by the so-called dipolar truncation effect. The study of rare spins on natural abundance allows to overcome this problem. In fact, with a natural abundance of 1.1 %, the probability for three 13C to be coupled is negligible. We developed a methodology based either on the dipolar recoupling NMR pulse sequence POST-C7 or on the dramatic increase in sensitivity provided by dynamic nuclear polarization. We demonstrated that its methodology provides a measure of 13C-13C dipolar couplings in natural abundance powder samples and that the so-obtained distance information is sensitive to both molecular conformation and crystal packing of powder samples. Moreover, we show that the recoupling pulse sequence R20_9_2 is more robust to strong chemical shift anisotropy and also to strong 1H-13C heteronuclear dipolar couplings than POST-C7. The second challenge involves 13C signal assignment for natural abundance. In fact, there are only a few examples of 13C-13C correlation spectra obtained for natural abundance samples. Here, we show that 13C-13C correlation spectra sequence based on the reintroduction of 13C−13C dipolar couplings can be obtained with standard MAS probe and within few days using R20_9_2 pulse sequence. Contrary to pulse sequences based on 13C-13C J coupling, our pulse sequence requires shorter DQ excitation time and hence, is more suitable for samples having short T2 relaxation times such as amorphous solids.

Atrial fibrillation (AF), the most common cardiac arrhythmia in persons over age 65, is associated with an increased stroke risk necessitating the need for long-term oral anticoagulation for risk reduction. With the introduction of direct thrombin and factor Xa inhibitors in the US since 2010, these novel oral anticoagulants (NOACs) are increasingly being prescribed, replacing the use of warfarin, a vitamin K antagonist. AF catheter ablation (CA), an elective procedure requiring femoral vascular access is a treatment for drug refractory and persistent AF. Bedrest, limb immobilization, and limited head of bed elevation are nursing measures utilized following femoral venous, and sometimes arterial, sheath removal and hemostasis. Limited research is available on the appropriate duration of bedrest to minimize bleeding complications associated with AF ablation in patients who use NOACs. The purpose of this quality improvement project was to compare and evaluate the effect of bedrest duration on post-procedure bleeding outcomes, urinary complaints, and back pain among patients taking NOACs while undergoing AFCA. Thirty patients undergoing elective AFCA on NOACs were orally consented to participate in the study and placed on shortened (8 hours) or prolonged (>8 hours) bedrest following vascular hemostasis. Outcome measurements included bleeding after ambulation, back pain, and urinary complaints. Fifteen patients (50%) were on shortened bedrest and 15 (50%) were on prolonged bedrest. No statistically significant difference in bleeding, urinary complaints, or back pain were found. Since there is no clear advantage to prolonged bedrest for patients on NOACS after an AFCA procedure, clinicians should consider this when deciding on bedrest duration for their patients.

Pre-diabetes is a serious health problem in the United States. Distinguished by plasma glucose levels that are above the normal threshold, patients with pre-diabetes are 10 times more likely to develop type 2 diabetes. Patients with pre-diabetes suffer the same complications as patients with diabetes including diabetic retinopathy, nephropathy, and microalbuminuria. There is considerable evidence to support the idea that early identification and aggressive treatment of pre-diabetes has the potential to delay disease progression. The American Diabetes Association’s clinical practice guideline recommends management of with lifestyle modification and metformin for patients who are at risk for developing type 2 diabetes. The purpose of this project was to evaluate the implementation of the 2012 ADA clinical practice guidelines regarding the management of patients with pre-diabetes by the health care providers at a volunteer-run clinic located in a large metropolitan area in the southeastern United States. This study, even with a small sample size (n=26) revealed that the providers at the clinic had not implemented the 2012 ADA clinical practice guidelines. Clinical practice guidelines promote health care interventions that have proven benefits and improve the consistency of care provided to patients. The greatest benefits of implementing clinical practice guidelines for patients with pre-diabetes are early diagnosis and aggressive disease management. This would improve patient outcomes and in the long run, decrease the cost of medical care.

Performance of hand hygiene is among the most effective means of preventing healthcare associated infections (HAI) among patients. Deaths resulting from HAIs are one of the top ten leading causes of death in the United States. Any improvement in the frequency of hand hygiene among healthcare professionals may have a direct impact on patient mortality and associated costs. While anesthesia professionals have been found to have low rates of hand hygiene adherence, few targeted studies seeking to improve hand hygiene adherence among this group exist. Studies conducted to improve hand hygiene among health care professionals have reported limited improvement, with overall inconclusive recommendations for improving prolonged hand hygiene adherence rates. The purpose of this project was to improve anesthesia professionals’ hand hygiene through encouragement of performance and education on the current state of research in the area of anesthesia associated HAIs. Hand hygiene rates were evaluated through measuring the amount of hand sanitizer used at eleven anesthesia workstations in the main operating room of a hospital. Measurements were taken at baseline and continued for three months after the educational program was implemented.

The purpose of this project was to evaluate the effectiveness of an educational lifestyle modification (LM) intervention on blood pressure (BP) among adults with prehypertension. Prehypertension is a precursor to hypertension (HTN) and is a public epidemic in the United States. Approximately 68 million (31%) U.S. adult’s aged ≥18 years have hypertension. Hypertension can cause significant target organ damage, lead to coronary heart disease, heart failure, stroke, and kidney failure. Early identification and the primary treatment of persons with prehypertension with LM have the potential to minimize the progression and delay the onset of comorbidities associated with hypertension. This quality improvement project retrospectively reviewed changes in blood pressure for a small sample (n=5) of patients diagnosed with prehypertension who received education about modifying lifestyle behaviors according to nationally accepted clinical practice guidelines. Blood pressure measurements were extracted from the medical record beginning at the time of the education through a three month period. Descriptive data indicates that all five patients had a decrease in systolic and diastolic blood pressure. The median systolic blood pressure at baseline was 129 mmHg decreasing to 121 mmHg at end of study period. The median diastolic blood pressure was 86 mmHg decreasing to 76 mmHg. Integration of lifestyle modification education and subsequent blood pressure monitoring during a routine primary care visit is feasible and may help motivate patients to implement changes and subsequently reduce blood pressure. Future studies should include identifying strategies for improving patient participation.

Background: Beta blockers are recommended by the American College of Cardiology/American Heart Association Guidelines for high and intermediate-risk cardiac patients undergoing non-cardiac surgery. Beta blockers are a class of drugs that moderate the effects of increased catecholamine levels on the heart by selectively blocking beta receptors in the heart and blood vessels, resulting in a lower heart rate and blood pressure. Beta blocker use perioperatively has been shown to reduce the risk of ischemia and infarction. Purpose: The purpose of this project is to address beta blocker use in a group of anesthesia providers who routinely attend to high-risk and intermediate-risk cardiac patients undergoing non-cardiac surgery in a medium-sized private hospital in suburban South Florida. There are barriers to the implementation of the published guidelines for beta blocker administration, including lack of awareness of the best current practice and a lack of a formal beta blocker protocol at the institutional level. Methods: A simple and inexpensive beta blocker protocol was implemented and evaluated by various means. Beta blocker administration practices were examined and documented prior to and after protocol implementation. Beta blocker usage was examined prior to and after protocol implementation Findings/Implications: It was hypothesized that increased anesthesia provider awareness would lead to increased administration of perioperative beta blockers to high-risk and intermediate-risk cardiac patients undergoing non-cardiac procedures. Although there was a knowledge increase related to the new beta blocker protocol, no change in practice was observed.

Knowledge of The Joint Commission's National Patient Safety Goals and an effective provider cooperative practice involving communication and teamwork are essential for the delivery of safe and compliant patient care in the surgical setting. The purpose of this study was to assess the impact of an educational intervention for physicians and nurses designed to increase documentation of compliance with national patient safety standards. As events of noncompliance have impacted patient safety at the hospital where this project was conducted, measures were needed to assess barriers to compliance with standards of practice and to focus educational session plans on identified knowledge-base needs. The goal of this project involved bringing all surgical team members together for educational sessions on safety standards. Pre-intervention and post-intervention assessments of knowledge were administered to study participants. Additionally, random chart documentation audits were conducted before and after the intervention to assess the effectiveness of the education sessions on documentation compliance with the targeted standards. Outcomes of this study included improved knowledge of, and compliance with, national patient safety goals. Results may improve safe patient care at this hospital, reduce costs, and create mutual respect and teamwork, all contributing to the successful achievement of the organization's quality improvement goals.

Since the first so-called “medical marijuana” legislation was passed in California in 1996, a total of twenty states and the District of Columbia have passed laws permitting limited use of cannabis. Despite the changes in state laws, cannabis remains illegal for any purpose under federal law. Changes in state laws have coincided with a renewed interest in the substance for the treatment of a variety of conditions. There has been a significant increase in published data over the past twenty years examining the efficacy of cannabis as an appetite stimulant, antiemetic agent, and analgesic adjuvant. The purpose of this meta-analysis was to synthesize published data on cannabis use as an analgesic agent. Five studies meeting inclusion criteria were located through searches of online databases, review of reference lists, author correspondence, and review of clinical trials databases. Meta-analysis was conducted using fixed-effects modeling. The overall effect of mean reduction of pain intensity was -4.895 (Z-score) with an associated p value of 0.003. The combined standardized mean difference (SMD) was -0.362 (CI -0.507 to -0.217), indicating on average a moderate significant reduction in pain intensity for patients with chronic pain. As the legal status of the substance evolves, additional research is needed to establish evidence-based clinical recommendations regarding the use of medicinal cannabis in pain management.

SerpinA12 (vaspin) is thought to be mainly expressed in adipose tissue and has multiple beneficial effects on metabolic, inflammatory and atherogenic processes related to obesity. KLK7 (kallikrein 7) is the only known protease target of vaspin to date and is inhibited with a moderate inhibition rate. In the crystal structure, the cleavage site (P1-P1′) of the vaspin reactive centre loop is fairly rigid compared with the flexible residues before P2, possibly supported by an ionic interaction of P1′ glutamate (Glu379) with an arginine residue (Arg302) of the β-sheet C. A P1′ glutamate seems highly unusual and unfavourable for the protease KLK7. We characterized vaspin mutants to investigate the roles of these two residues in protease inhibition and recognition by vaspin. Reactive centre loop mutations changing the P1′ residue or altering the reactive centre loop conformation significantly increased inhibition parameters, whereas removal of the positive charge within β-sheet C impeded the serpin–protease interaction. Arg302 is a crucial contact to enable vaspin recognition by KLK7 and it supports moderate inhibition of the serpin despite the presence of the detrimental P1′ Glu379, which clearly represents a major limiting factor for vaspin-inhibitory activity. We also show that the vaspin-inhibition rate for KLK7 can be modestly increased by heparin and demonstrate that vaspin is a heparin-binding serpin. Noteworthily, we observed vaspin as a remarkably thermostable serpin and found that Glu379 and Arg302 influence heat-induced polymerization. These structural and functional results reveal the mechanistic basis of how reactive centre loop sequence and exosite interaction in vaspin enable KLK7 recognition and regulate protease inhibition as well as stability of this adipose tissue-derived serpin.