1,382 research outputs found
UTILITE ET EFFICACITE DU CATHETERISME SELECTIF DES VEINES SURRENALIENNES LORS D'UN HYPERALDOSTERONISME PRIMAIRE, REVUE DES 5 DERNIERES ANNEES AU CHUV
Contexte
L'hyperaldostéronisme primaire (HAP) est actuellement considéré comme la première cause d'hypertension artérielle secondaire. Son diagnostic est capital car il permet d'identifier des patients avec une cause potentiellement réversible d'hypertension. Cependant, le diagnostic et l'attitude thérapeutique (traitement médical vs. chirurgical) ne sont pas toujours évidents. Le cathétérisme sélectif des veines surrénaliennes (CVS) permet la détermination d'une latéralisation de la sécrétion d'aldostérone avec moins de risques de faux négatifs et de faux positifs que l'imagerie par scanner ou par IRM. Contrairement à d'autres pays européens, asiatiques ou américains, il n'existe pour le moment aucune donnée publiée sur le cathétérisme des veines surrénaliennes en Suisse.
Objectifs
Déterminer le taux de succès du CVS ainsi que ses déterminants cliniques au cours des 5 dernières années au CHUV, ainsi que démontrer l'utilité d'un cathétérisme des veines surrénaliennes lorsqu'une surrénalectomie est envisagée dans le cadre d'un hyperaldostéronisme primaire
Méthodes
Cette étude est rétrospective et monocentrique. La récolte de données s'est faite à partir de dossiers de 68 patients atteints d'hypertension artérielle (HTA) secondaire sur HAP biochimiquement confirmé et ayant eu un CVS au cours des 5 dernières années.
Résultats
Au CHUV, le taux de succès du CVS (cathétérisme bilatéral des veines surrénaliennes) s'élève à 60% (41/68). Dans 53% des cas, il y a discordance entre les résultats de l'imagerie standard et ceux du CVS. Une attitude thérapeutique basée sur l'imagerie standard aurait entrainé des traitements inappropriés : 43% des patients auraient subi une chirurgie inadéquate, et 10% n'auraient pas été candidats à une sanction chirurgicale alors qu'elle aurait été indiquée sur la base du CVS.
Conclusions
Le CVS doit être considéré comme l'étalon-or dans la prise en charge diagnostique de l'HAP lorsqu'une intervention chirurgicale est possible. En se basant uniquement sur l'imagerie, il en résulterait un taux élevé de traitement inapproprié. Aux vues des difficultés techniques associées à cet examen, de nouvelles procédures doivent être mises en place pour mener à une amélioration de son taux de succès et à l'interprétation des résultats
Beyond Binary Search: Parallel In-Place Construction of Implicit Search Tree Layouts.
M.S. Thesis. University of Hawaiʻi at Mānoa 2018
Interacting many-body systems in quantum wells: Evidence for exciton-trion-electron correlations
We report on the nonlinear optical dynamical properties of excitonic
complexes in CdTe modulation-doped quantum wells, due to many-body interactions
among excitons, trions and electrons. These were studied by time and spectrally
resolved pump-probe experiments. The results reveal that the nonlinearities
induced by trions differ from those induced by excitons, and in addition they
are mutually correlated. We propose that the main source of these subtle
differences comes from the Pauli exclusion-principle through phase-space
filling and short-range fermion exchange.Comment: 5 pages, 4 figures. accepted for publications in Phys. Rev.
Light dressed-excitons in an incoherent-electron sea: Evidence for Mollow-triplet and Autler-Townes doublet
We demonstrate that the interaction between excitons and a sea of incoherent
electrons does not preclude excitons dressing by light. We investigate the role
of exciton-electron scattering in the light dressing by measuring the dynamical
absorption spectrum of a modulation-doped CdTe quantum well, which shows a
clear evidence for significant electron scattering of the excitonic states. We
show the occurrence of dressed and correlated excitons by detecting quantum
coherent interferences through excitonic Autler-Townes doublet and ac Stark
splitting, which evolves to Mollow triplet with gain. We also evidence the
partial inhibition of the electron-exciton scattering by exciton-light
coupling
Concept of Formation Length in Radiation Theory
The features of electromagnetic processes are considered which connected with
finite size of space region in which final particles (photon, electron-positron
pair) are formed. The longitudinal dimension of the region is known as the
formation length. If some external agent is acting on an electron while
traveling this distance the emission process can be disrupted. There are
different agents: multiple scattering of projectile, polarization of a medium,
action of external fields, etc. The theory of radiation under influence of the
multiple scattering, the Landau-Pomeranchuk-Migdal (LPM) effect, is presented.
The probability of radiation is calculated with an accuracy up to "next to
leading logarithm" and with the Coulomb corrections taken into account. The
integral characteristics of bremsstrahlung are given, it is shown that the
effective radiation length increases due to the LPM effect at high energy. The
LPM effect for pair creation is also presented. The multiple scattering
influences also on radiative corrections in a medium (and an external field
too) including the anomalous magnetic moment of an electron and the
polarization tensor as well as coherent scattering of a photon in a Coulomb
field. The polarization of a medium alters the radiation probability in soft
part of spectrum. Specific features of radiation from a target of finite
thickness include: the boundary photon emission, interference effects for thin
target, multi-photon radiation. The experimental study of LPM effect is
described. For electron-positron colliding beams following items are discussed:
the separation of coherent and incoherent mechanisms of radiation, the
beam-size effect in bremsstrahlung, coherent radiation and mechanisms of
electron-positron creation.Comment: Revised review paper, 96 pages, 28 figures. Description of SLAC E-146
experiment removed, discussion of CERN SPS experiment adde
Direct measure of the exciton formation in quantum wells from time resolved interband luminescence
We present the results of a detailed time resolved luminescence study carried
out on a very high quality InGaAs quantum well sample where the contributions
at the energy of the exciton and at the band edge can be clearly separated. We
perform this experiment with a spectral resolution and a sensitivity of the
set-up allowing to keep the observation of these two separate contributions
over a broad range of times and densities. This allows us to directly evidence
the exciton formation time, which depends on the density as expected from
theory. We also evidence the dominant contribution of a minority of excitons to
the luminescence signal, and the absence of thermodynamical equilibrium at low
densities
Study protocol for the ETMED-L project: longitudinal study of mental health and interpersonal competence of medical students in a Swiss university using a comprehensive framework of empathy.
Physician interpersonal competence is crucial for patient care. How interpersonal competence develops during undergraduate medical education is thus a key issue. Literature on the topic consists predominantly of studies on empathy showing a trend of decline over the course of medical school. However, most existing studies have focused on narrow measures of empathy. The first aim of this project is to study medical students' interpersonal competence with a comprehensive framework of empathy that includes self-reported cognitive and affective empathy, performance-based assessments of emotion recognition accuracy, and a behavioural dimension of empathy. The second aim of the present project is to investigate the evolution of mental health during medical school and its putative link to the studied components of interpersonal competence. Indeed, studies documented a high prevalence of mental health issues among medical students that could potentially impact their interpersonal competence. Finally, this project will enable to test the impact of mental health and interpersonal competence on clinical skills as evaluated by experts and simulated patients.
This project consists of an observational longitudinal study with an open cohort design. Each year during the four consecutive years of the project, every medical student (curriculum years 1-6) of the University of Lausanne in Switzerland will be asked to complete an online questionnaire including several interpersonal competence and mental health measures. Clinical skills assessments from examinations and training courses with simulated patients will also be included. Linear mixed models will be used to explore the longitudinal evolutions of the studied components of interpersonal competence and mental health as well as their reciprocal relationship and their link to clinical skills.
The project has received ethical approval from the competent authorities. Findings will be disseminated through internal, regional, national and international conferences, news and peer-reviewed journals
Clinical determinants of adrenal vein sampling success
Background: Primary aldosteronism (PA) is one of the most prevalent
forms of secondary hypertension, which may be cured by unilateral adrenalectomy.
Adrenal vein sampling (AVS) is considered the gold-standard
procedure for distinction between bilateral and unilateral aldosterone hypersecretion.
However, the procedure is viewed as a technical challenge.
The objectives of this study were to define the success rate of AVS, and its
clinical determinants, and to compare the accuracy of high-resolution adrenal
computed tomography (CT) with AVS.
Methods: In this single-centre retrospective study, patients with biologically
proven PA who were referred for AVS between 2009 and 2014
were included. Adrenal vein catheterisation was considered selective if the
selectivity index (adrenal vein / inferior vena cava cortisol) was ≥2.
Results: Data from 68 patients (48% women) were available. The success
rate of catheterisation in bilateral AVS was 60% (41/68). The significant
clinical determinants of success were male sex (r = 0.35, p = 0.004), a
higher body mass index (BMI) (r = 0.54, p = 0.001) and plasma creatinine
(r = 0.25, p = 0.048) in univariate analysis. In multivariate linear regression
analysis, only BMI was associated with success (coefficient = 0.049,
p = 0.004). CT was discordant with AVS in 53% of patients, and would have
resulted in inappropriate adrenalectomy in 43% of the patients and inappropriate
exclusion from surgery in 10% of the cases.
Conclusion: Clinical characteristics such as BMI and sex may influence the
success rate of AVS. The inaccuracy of CT may result in inappropriate
treatment proposals if the indication for surgical intervention is based on
CT only
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