Nonpersistence of resonant caustics in perturbed elliptic billiards

Caustics are curves with the property that a billiard trajectory, once tangent to it, stays tangent after every reflection at the boundary of the billiard table. When the billiard table is an ellipse, any nonsingular billiard trajectory has a caustic, which can be either a confocal ellipse or a confocal hyperbola. Resonant caustics —the ones whose tangent trajectories are closed polygons— are destroyed under generic perturbations of the billiard table. We prove that none of the resonant elliptical caustics persists under a large class of explicit perturbations of the original ellipse. This result follows from a standard Melnikov argument and the analysis of the complex singularities of certain elliptic functions.

Functional late outgrowth endothelial progenitors isolated from peripheral blood of burned patients.

BACKGROUND: Bioengineered skin substitutes are increasingly considered as a useful option for the treatment of full thickness burn injury. Their viability following grafting can be enhanced by seeding the skin substitute with late outgrowth endothelial progenitor cells (EPCs). However, it is not known whether autologous EPCs can be obtained from burned patients shortly after injury. METHODS: Late outgrowth EPCs were isolated from peripheral blood sampled obtained from 10 burned patients (extent 19.6±10.3% TBSA) within the first 24h of hospital admission, and from 7 healthy subjects. Late outgrowth EPCs were phenotyped in vitro. RESULTS: In comparison with similar cells obtained from healthy subjects, growing colonies from burned patients yielded a higher percentage of EPC clones (46 versus 17%, p=0.013). Furthermore, EPCs from burned patients secreted more vascular endothelial growth factor (VEGF) into the culture medium than did their counterparts from healthy subjects (85.8±56.2 versus 17.6±14pg/mg protein, p=0.018). When injected to athymic nude mice 6h after unilateral ligation of the femoral artery, EPCs from both groups of subjects greatly accelerated the reperfusion of the ischaemic hindlimb and increased the number of vascular smooth muscle cells. CONCLUSIONS: The present study supports that, in patients with burns of moderate extension, it is feasible to obtain functional autologous late outgrowth EPCs from peripheral blood. These results constitute a strong incentive to pursue approaches based on using autotransplantation of these cells to improve the therapy of full thickness burns.

Critical evaluation of outcome scales assessment of lateral ankle ligament reconstruction

Introduction: Les résultats d'une chirurgie du pied et de la cheville peuvent être évalués par des scores spécifiques à la région anatomique ainsi que par des scores spécifiques à la pathologie. Beaucoup de scores existent rendant la comparaison entre les études difficile. La présente étude se focalise sur une pathologie fréquente du pied et de la cheville et compare les résultats obtenu par deux scores spécifiques à la région et deux scores spécifiques à la pathologie. Méthode: Nous avons revu 41 patients ayant bénéficié d'une plastie ligamentaire externe de la cheville. Quatre scores ont été administrés simultanément: the Cumberland Ankle Instability Tool (CAIT) et the Chronic Ankle Instability Scale (CAIS), spécifiques à la pathologie, the American Orthopedic Foot & Ankle Society (AOFAS) hindfoot scale et the Foot and Ankle Ability Measure comprenant deux parties (FAAM1 et FAAM2), spécifiques à la région anatomique. Le degré de corrélation entre les scores a été évalué par le coefficient de corrélation de Pearson. L'analyse graphique des variances a été utilisée pour le choix de tests paramétriques versus non paramétriques. Des tests non paramétriques, le Kruskal-Wallis pour éliminer l'hypothèse nulle et le Mann-Whitney pour la comparaison entre les scores deux à deux, ont été utilisés. Résultats: Une différence significative (p<.005) a été démontrée entre le CAIS et l'AOFAS (p=.0002), entre le CAIS et le FAAM1 (p=.0001) et entre le CAIT et l'AOFAS (p=.0003) Conclusions: Cette étude compare les performances de quatre scores dont deux spécifiques à la région anatomique et deux spécifiques à la pathologie. Nous avons démontré une bonne corrélation entre les scores ainsi que des différences significatives entre les résultats obtenus par chacun d'eux. Les résultats obtenus par les scores spécifiques à la pathologie semblent être plus précis que ceux obtenus par les scores spécifiques à la région anatomique. De plus, nous avons mis en évidence une forte corrélation entre l'AOFAS et les autres scores. Le FAAM semble être un bon compromis car il offre la possibilité, du fait de ses deux parties, d'évaluer le résultat en fonction de la demande fonctionnelle du patient. Perspectives: Un algorithme est proposé qui permet d'évaluer la littérature spécifique de manière plus critique et peut s'adapter également à la recherche et à la clinique relative à d'autres pathologies du pied et de la cheville

A morphological grading of spinal stenosis: a radiological study on LSS and LBP patients : P173

Introduction: Clinical symptoms and degree of spinal stenosis based on cross sectional dural sac area correlate only weakly in lumbar spinal stenosis (LSS) patients. We conceived a four grade classification system (A, B, C & D) based on the morphology of the dural sac and its contents as seen on T2 axial MRI images. The categories take into account the rootlet/CSF ratio. We applied this grading to three patient groups: LSS scheduled for surgery; LSS following conservative treatment and patients with low back pain (LBP) without leg pain. Materials/Methods: A total of 346 T2 axial MRI images taken from LSS and LBP patients were included in this retroperspective study. 37 patients had decompressive surgery (132 MRI images), 31 conservative treatment (116 MRI images) and 27 patients had unspecific LBP (98 MRI images). Dural sac cross-sectional surface area and morphological grading of the canal were measured digitally both at disc and pedicle level. Intra- and inter-observer reliability were assessed (weighted Cohen's kappa statistics) from 50 MRI images taken from the surgery group. Results: At the most severe disc level, grade A (mild stenosis) was found in 3% of MRI images of the surgical group as opposed to 51% in the conservatively treated group and 85% in the LBP group. Grade B occurred in 8% of the surgical, 20% of the conservative and was negligible in LBP group (below 1%). Grade C and D (severe stenosis) was found in 89% of the surgical group, as opposed to 30% in conservative group and 11% in LBP group. The grades of all groups were comparable at the pedicle levels, exhibiting in 94% a grade A with a maximum at the A1 grade. Pedicle and disc level cross-sectional area were smallest in the surgery group and smaller in the conservative group as compared to the LBP group at the levels L2, L3 and L4. According to cross-sectional area measurements patients from the surgery group seems to have smaller vertebral canal although this was not related to smaller stature. Validation of grading: Average intra-and inter observer kappas were 0.76 and 0.69 respectively, for physicians working in the study originating institution. Combining all observers the kappa values were 0.57 +/- 0.19. and 0.44 +/- 0.19 respectively. Dural sac cross-sectional area measurements showed no statistically significant differences between observers. Conclusion: Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. In our institution Grade A stenosis was less likely to require surgical treatment. This grading can therefore be an aid in surgical patient selection in teaching units.

Learning collaboration in General Internal Medicine: a pilot project for undergraduate students in nursing, physiotherapy and medicine

Background: A form of education called Interprofessional Education (IPE) occurs when two or more professions learn with, from and about each other. The purpose of IPE is to improve collaboration and the quality of care. Today, IPE is considered as a key educational approach for students in the health professions. IPE is highly effective when delivered in active patient care, such as in clinical placements. General internal medicine (GIM) is a core discipline where hospital-based clinical placements are mandatory for students in many health professions. However, few interprofessional (IP) clinical placements in GIM have been implemented. We designed such a placement. Placement design: The placement took place in the Department of Internal Medicine at the CHUV. It involved students from nursing, physiotherapy and medicine. The students were in their last year before graduation. Students formed teams consisting of one student from each profession. Each team worked in the same unit and had to take care of the same patient. The placement lasted three weeks. It included formal IP sessions, the most important being facilitated discussions or "briefings" (3x/w) during which the students discussed patient care and management. Four teams of students eventually took part in this project. Method: We performed a type of evaluation research called formative evaluation. This aimed at (1) understanding the educational experience and (2) assessing the impact of the placement on student learning. We collected quantitative data with pre-post clerkship questionnaires. We also collected qualitative data with two Focus Groups (FG) discussions at the end of the placement. The FG were audiotaped and transcribed. A thematic analysis was then performed. Results: We focused on the qualitative data, since the quantitative data lacked of statistical power due to the small numbers of students (N = 11). Five themes emerged from the FG analysis: (1) Learning of others' roles, (2) Learning collaborative competences, (3) Striking a balance between acquiring one's own professional competences and interprofessional competences, (4) Barriers to apply learnt IP competences in the future and (5) Advantages and disadvantages of IP briefings. Conclusions: Our IP clinical placement in GIM appeared to help students learn other professionals' roles and collaborative skills. Some challenges (e.g. finding the same patient for each team) were identified and will require adjustments.

Plaisir et souffrance au travail : une lecture psychodynamique au sein d'un office régional de placement suisse

En Suisse, comme dans la plupart des pays industrialisés, le stress au travail et l'épuisement qui en découle sont devenus, au cours des dernières décennies, une réalité qui ne cesse de s'accentuer. Différentes disciplines scientifiques ont tenté de rendre compte, depuis le milieu du siècle dernier, des difficultés rencontrées par les individus dans le cadre de leur travail, avec une prédominance marquée pour des analyses de type causaliste. Dans le cadre de cette étude doctorale, nous nous sommes penché sur le cas d'un office régional de placement, mais avec une perspective sensiblement différente. La grille de lecture psychodynamique utilisée permet en effet de donner accès au sens des situations de travail et d'ouvrir sur une compréhension originale des mécanismes à l'origine des problèmes de santé mentale au travail. Cette approche permet ainsi de comprendre les rapports complexes que les individus entretiennent avec leur travail tel que structuré et organisé, et d'analyser leur expérience en termes de plaisir, de souffrance, de défenses face à la souffrance et de répercussions sur la santé. Dans ce but, nous avons utilisé une méthodologie basée sur des entrevues collectives, afin de stimuler l'expression libre des travailleurs. L'enquête s'est déroulée en deux temps : une première série d'entretiens de groupe a permis la récolte des données empiriques, puis une seconde série, appelée entretiens de restitution, a donné la possibilité aux participants de réagir sur l'interprétation de leur parole faite par le chercheur, et de valider l'analyse. Nos résultats mettent alors en évidence que le travail, tel qu'organisé au sein de cette institution de service public, apparaît considérablement pathogène, mais heureusement compensé par le pouvoir structurant de la relation d'aide aux assurés. Ils montrent également que l'expérience subjective de travail des participants a pour principales sources de souffrance la perception désagréable d'un manque de reconnaissance, d'autonomie et de pouvoir sur leurs actes. - In Switzerland and in other industrialized countries, work-related stress and resulting burn-out has become an ever increasing problem in recent decades. Many researchers Jrom many different fields have made efforts to understand the difficulties employees encounter at work since the middle of the last century. Most of this research is based on a cause and effect analysis approach. For this doctoral research project, we have analyzed cases handled by an unemployment office in Switzerland. We have taken a novel approach by using a number of psychodynamic criteria which permitted us to interpret situations at work and to open up a new way of understanding the mechanisms at work which lead to mental health problems. This approach allows us to understand account the complex relationship people have towards structured and organized work as well as to take into account and to analyze their experience in terms of pleasure, suffering, defense mechanisms against suffering and the consequences on their mental health. In order to achieve this goal we performed collective interviews in order to encourage workers to express themselves freely. The interviews were divided into two series. The first series of group interviews allowed us to collect empirical statistics and the second series gave the workers an opportunity to react to the researchers ' analysis of their answers and to validate the researchers ' interpretation of their answers. Our results show that work has considerable negative effects on mental health. Fortunately, these negative effects are counterbalanced by the psychological support system offered by the unemployment office. Our project also shows that the subjective negative experiences of workers are caused by their perceptions of being under-appreciated, lack of autonomy and having no power over their acts.

Une conséquence d'un état de stress chronique au travail : dossier

Le burn-out ou syndrome d'épuisement professionnel (Z73.0 selon le CIM-10) a été décrit la première fois en 1980 par le psychanalyste Freudenberger puis repris par Maslach et Jackson en 1986. [Auteure]

Functional late outgrowth endothelial progenitors isolated from peripheral blood of burned patients.

BACKGROUND: Bioengineered skin substitutes are increasingly considered as a useful option for the treatment of full thickness burn injury. Their viability following grafting can be enhanced by seeding the skin substitute with late outgrowth endothelial progenitor cells (EPCs). However, it is not known whether autologous EPCs can be obtained from burned patients shortly after injury. METHODS: Late outgrowth EPCs were isolated from peripheral blood sampled obtained from 10 burned patients (extent 19.6±10.3% TBSA) within the first 24h of hospital admission, and from 7 healthy subjects. Late outgrowth EPCs were phenotyped in vitro. RESULTS: In comparison with similar cells obtained from healthy subjects, growing colonies from burned patients yielded a higher percentage of EPC clones (46 versus 17%, p=0.013). Furthermore, EPCs from burned patients secreted more vascular endothelial growth factor (VEGF) into the culture medium than did their counterparts from healthy subjects (85.8±56.2 versus 17.6±14pg/mg protein, p=0.018). When injected to athymic nude mice 6h after unilateral ligation of the femoral artery, EPCs from both groups of subjects greatly accelerated the reperfusion of the ischaemic hindlimb and increased the number of vascular smooth muscle cells. CONCLUSIONS: The present study supports that, in patients with burns of moderate extension, it is feasible to obtain functional autologous late outgrowth EPCs from peripheral blood. These results constitute a strong incentive to pursue approaches based on using autotransplantation of these cells to improve the therapy of full thickness burns.

Boerhaave Syndrom: an unusual complication of acute vomiting in a child

Introduction: Boerhaave syndrome (BS) is a spontaneous esophageal perforation, described in aged, alcoholic males, secondary to forceful vomiting. BS has rarely been described in children. Case presentation: The patient is a 7-year-old Nigerian girl. She has a past history of clinical gastro-esophageal reflux (treated conservatively with prokinetics and good evolution), malaria at the age of 3 months and an episode of acute pancreatitis at 5 years. One week prior admission, she had stopped atovaquone-proguanil (AP) prophylaxis after a trip in an endemic area. Two days prior admission, she presented several bouts of isolated acute vomiting, without fever or diarrhea. On admission, she complained of chest pain. Cardiac auscultation revealed crepitus. No subcutaneous emphysema nor respiratory distress was present. Chest radiography and CT-scan confirmed a pneumomediastinum extending to the neck. Esophageal perforation was suspected. An upper gastrointestinal endoscopy was performed and showed a small esophageal tear, grade II-III esophagitis and a single gastric ulcer without any sign of H. Pylori infection. Enteral feeds were stopped and a nasogastric sucking tube inserted. The patient made a full recovery on intravenous antibiotics and conservative treatment. Of note a second episode of subclinical acute pancreatitis, treated conservatively, probably drug-induced. Discussion: BS is a complete rupture of all layers of the esophagus, secondary to an increased intra-abdominal pressure due to incomplete opening of the cricophayngeal sphincter occurring during vomiting or cough. Rarer causes include eosinophilic or Barrett's esophagitis, HIV and caustic ingestion. Esophageal perforation in children is rare, most of time secondary to necrotizing esophagitis in the newborn, medical intervention (endoscopy, sucking, or intubation) or trauma in the older child. Our patient had none of those risk factors and it is still unclear what predisposed her to this complication. However, we believe that preceding forceful vomiting with increased abdominal pressure acting on a weakened oesophagus due to esophagitis might be responsible. We could not find any association in the literature between AP and BS nor between BS and acute pancreatitis. The origin of her recurrent pancreatitis remains unclear, reason for which genetic testing for mutations in the trypsinogen, trypsin inhibitor and CFTR genes will be performed in case of a third episode.

Guía de práctica clínica para el cuidado de personas que sufren quemaduras

Publicaciones complementarias: Folleto: Guía de prevención y cuidados de las personas con quemaduras. Folleto desplegable: Guía rápida de consulta para el cuidado de personas que sufren quemaduras

Entrevista y urgencia social: un reto para las competencias profesionales del educador social

Si decimos que los seres humanos sólo son capaces de vivir como tales mediante la reconstrucción narrativa de sus experiencias, estamos teniendo en cuenta conceptos e ideas que recuerdan a algunos autores contemporáneos (Ricoeur, Gadamer) que defienden la importancia de ser reconocido como una creatura hecha de palabras. En la medida en que son interpretadas, traducidas, contextualizadas y ordenadas por los profesionales, la situación dialogal significativa cobra importancia. Desde esta perspectiva hemos planteado las asignaturas: Habilidades Sociales, Técnicas de Entrevista y Gestión de Situación de Crisis diseñadas para integrar los diferentes modelos teóricos y las variables que se presentan en la relación comunicativa con el usuario y en particular en la situación de entrevista. Se mostrará también el modo cómo en nuestro proceso formativo, basado en la simulación de situaciones, se fomenta el compromiso con el trabajo en equipo, la autocomprensión y enseña a crear un clima de trabajo cooperativo en el que se hace más eficaz la relación de ayuda. A través de la presentación en clase de un caso práctico en el cual se describen todos los procedimientos y las fases del que se compone el ejercicio de la práctica profesional –paso a paso-, se busca poner de manifiesto las competencias adquiridas, los modelos empleados y las habilidades sociales que han sido necesarias para afrontar con éxito la situación de urgencia social. Finalmente se deja abierta la cuestión sobre la manera en que incide y beneficia este aprendizaje en las futuras situaciones de manejo del estrés profesional (burn out).

Development of a cost-effective method for platelet-rich plasma (PRP) preparation for topical wound healing.

Platelet-rich plasma (PRP) is a volume of plasma fraction of autologous blood having platelet concentrations above baseline whole-blood values due to processing and concentration. PRP is used in various surgical fields to enhance soft-tissue and bone healing by delivering supra-physiological concentrations of autologous platelets at the site of tissue damage. These preparations may provide a good cellular source of various growth factors and cytokines, and modulate tissue response to injury. Common clinically available materials for blood preparations combined with a two-step centrifugation protocol at 280g each, to ensure cellular component integrity, provided platelet preparations which were concentrated 2-3 fold over total blood values. Costs were shown to be lower than those of other methods which require specific equipment and high-cost disposables, while safety and traceability can be increased. PRP can be used for the treatment of wounds of all types including burns and also of split-thickness skin graft donor sites, which are frequently used in burn management. The procedure can be standardized and is easy to adapt in clinical settings with minimal infrastructure, thus enabling large numbers of patients to benefit from a form of cellular therapy.

Evaluation of a modified Broström-Gould procedure for treatment of chronic lateral ankle instability: A retrospective study with critical analysis of outcome scoring.

BACKGROUND: Chronic lateral ankle instability accounts for 20% of the ankle injuries. This study evaluates functional outcome of the modified Broström-Gould technique using suture anchors, with 4 different clinical scores. METHODS: A consecutive series of 41 patients were included with a minimum follow-up of one year. The function was assessed using 4 clinical scores including: the AOFAS for hind foot; the FAAM; the CAIT and the CAIS. RESULTS: Out of 41 patients; 27 patients were very satisfied, 11 satisfied and 3 were not satisfied. Ankle mobility returned to normal in 93% of patients. At follow-up the AOFAS was 89/100 (37-100), the FAAM 85/100% (35-100%), the CAIT 20/30 (5-30), and the CAIS 74/100% (27-100%). CONCLUSION: Outcome of modified Broström-Gould procedure is good with high satisfaction rate in terms of ankle mobility. The disparity in outcome of scores, signals towards the need of a standard evaluation system.

Introducing a new MRI classification of lumbar spinal stenosis based on cross-sectional morphology of the dural sac : 37

Introduction: Measures of the degree of lumbar spinal stenosis (LSS) such as antero-posterior diameter of the canal, and dural sac cross sectional area vary, and do not correlate with symptoms or results of surgery. We created a grading system, comprised of seven categories, based on the morphology of the dural sac and its contents as seen on T2 axial images. The categories take into account the ratio of rootlet/ CSF content. Grade A indicates no significant compression, grade D is equivalent to a total myelograhic block. We compared this classification with commonly used criteria of severity of stenosis. Methods: Fifty T2 axial MRI images taken at disc level from 27 symptomatic LSS patients undergoing decompressive surgery were classified twice by two radiologists and three spinal surgeons working at different institutions and countries. Dural sac cross-sectional surface area and AP diameter of the canal were measured both at disc and pedicle level from DICOM images using OsiriX software. Intraand inter-observer reliability were assessed using Cohen's, Fleiss' kappa statistics, and t test. Results: For the morphological grading the average intra-and inter observer kappas were 0.76 and 0.69+, respectively, for physicians working in the study originating country. Combining all observers the kappa values were 0.57 ± 0.19. and 0.44 ± 0.19, respectively. AP diameter and dural sac cross-sectional area measurements showed no statistically significant differences between observers. No correlation between morphological grading and AP diameter or dural sac crosssectional areawas observed in 13 (26%) and 8 cases (16%), respectively. Discussion: The proposed morphological grading relies on the identification of the dural sac and CSF better seen on full MRI series. This was not available to the external observers, which might explain the lower overall kappa values. Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. The absence of a strict correlation with the dural sac surface suggests that measuring the surface alone might be insufficient in defining LSS as it is essentially a mismatch between the spinal canal and its contents. This grading is now adopted in our unit and further studies concentrating on relation between morphology, clinical symptoms and surgical results are underway.