1,185 research outputs found
Etude de l'eĢvolution des patients porteurs d'une cardiomyopathie hypertrophique obstructive (CMHO) apreĢs alcoolisation septale
La cardiomyopathie hypertrophique (CMH) est la maladie cardiaque monogeĢnique la plus freĢquente, touchant environ 1 individu sur 500 dans la population (1,2). L'eĢtiologie est familiale dans la majoriteĢ des cas avec une transmission de type autosomal dominant aĢ peĢneĢtrance variable. Deux geĢnes principaux sont aĢ l'origine de la maladie chez 70% des patients avec un test geĢneĢtique positif. Il s'agit des geĢnes qui codent pour la chaine lourde Ī² de la myosine (MYH7) et la proteĢine C liant la myosine (MYBPC3) (1-3).
La CMH est deĢfinie par la preĢsence d'une hypertrophie myocardique Ā« inadeĢquate Ā» car se deĢveloppant en l'absence d'une cause d'augmentation de la post-charge (HTA, steĢnose aortique, membrane sous-aortique), d'une pathologie infiltrative ou d'un entrainement physique (4,5). Le plus souvent asymeĢtrique et affectant preĢfeĢrentiellement le septum, cette hypertrophie s'accompagne dans preĢs de deux tiers des cas d'une obstruction dynamique sous-aortique de la chambre de chasse du ventricule gauche par la valve mitrale (systolic anterior motion ou SAM). Cette obstruction est aĢ la fois la conseĢquence du reĢtreĢcissement de la chambre de chasse par l'hypertrophie septale mais eĢgalement d'un malpositionnement de la valve mitrale (6-8). On parle alors de Cardiomyopathie Hypertrophique et Obstructive (CMHO). L'obstruction - preĢsente au repos dans 50% des cas et uniquement apreĢs manoeuvres de provocation dans l'autre moitieĢ des cas (manoeuvre de Valsalva, test de vasodilatation par nitrite d'amyle) est aĢ l'origine d'un gradient de pression entre le ventricule gauche et l'aorte, et donc d'une surcharge de pression pour le ventricule gauche. Cette surcharge de pression est aĢ l'origine des symptoĢmes classiquement rencontreĢs soit dyspneĢe et angor d'effort, preĢsyncope voire syncopes aĢ l'effort. Un gradient sous-aortique de plus de 50 mmHg (mesureĢ au repos ou apreĢs provocation) est consideĢreĢ comme un gradient aĢ valeur pronostique (6-8) et justifiant un traitement si associeĢ aĢ des symptoĢmes.
Le traitement meĢdical des formes obstructives repose sur l'administration de substances inotropes neĢgatives et/ou susceptibles de favoriser la relaxation myocardique tels que les beĢta-bloqueurs, les antagonistes du calcium et le disopyramide - pris isoleĢment ou en association. Pour les nombreux patients qui deviennent reĢfractaires ou intoleĢrants aĢ ces traitements, deux interventions peuvent leur eĢtre proposeĢes pour lever l'obstruction : une myotomie-myectomie chirurgicale du septum (9,10) ou une alcoolisation du septum par voie percutaneĢe (7,8). Les indications aĢ ces interventions sont les suivantes (7,8,11) :
1. SymptoĢmes (dyspneĢe de classe fonctionnelle NYHA III ou IV, angor de classe fonctionnelle CCS III ou IV, syncope, ou preĢsyncope) reĢfractaires au traitement meĢdical ou intoleĢrance du patient au traitement. Une dyspneĢe de classe II est consideĢreĢe suffisante dans le cas de jeunes patients.
2. Obstruction sous-aortique avec gradient supeĢrieur ou eĢgal aĢ 50 mmHg, au repos ou apreĢs manoeuvre de provocation, associeĢe aĢ une hypertrophie septale et aĢ un mouvement systolique anteĢrieur de la valve mitrale (effet SAM)
3. AnatomiecardiaquefavorableaĢuntraitementinvasif(eĢpaisseurduseptumde plus de 16 mm)
Si la myectomie chirurgicale reste la meĢthode de reĢfeĢrence (12-18), l'alcoolisation septale du myocarde par voie percutaneĢe est devenue un des traitements de choix dans la theĢrapie de la Cardiomyopathie Hypertrophique Obstructive reĢfractaire. Elle consiste aĢ repeĢrer par coronarographie l'arteĢre septale nourrissant le septum basal hypertrophieĢ, puis aĢ y introduire un petit ballon pour isoler ce territoire du reste du lit coronaire avant d'y injecter une dose d'alcool aĢ 95% comprise entre 1 et 5 cc. On creĢe ainsi un infarctus chimique, technique qui fut dans le passeĢ utiliseĢe pour le traitement de certaines tumeurs. Les effets ne sont pas immeĢdiats et neĢcessitent geĢneĢralement 2-3 semaines avant de se manifester. On assiste alors aĢ une diminution progressive de l'eĢpaisseur du myocarde neĢcroseĢ (7), aĢ la disparition progressive de l'obstruction et aĢ l'ameĢlioration / disparition des symptoĢmes.
La question de savoir qui de la chirurgie ou de l'alcoolisation est le plus efficace a eĢteĢ source de nombreux deĢbats (7,11-13,18).
Par rapport aĢ la chirurgie, les avantages de la meĢthode percutaneĢe sont les suivants (11,14,15,18,19) :
- EfficaciteĢs heĢmodynamique et fonctionnelle jugeĢes comparable aĢ la chirurgie selon les eĢtudes
- Taux de morbiditeĢ et de mortaliteĢ treĢs faible et non supeĢrieure aĢ la chirurgie
- Absence de sternotomie
- Diminution de la dureĢe de l'hospitalisation et surtout de la peĢriode de
convalescence, le patient pouvant reprendre une activiteĢ deĢs son retour aĢ domicile
Certains experts eĢmettent neĢanmoins des doutes quant aĢ l'innocuiteĢ aĢ long terme de la meĢthode, les zones neĢcrotiques pouvant servir de terrain arythmogeĢne. Pour ces raisons, la meĢthode n'est pas recommandeĢe chez les patients de moins de 40 ans (6,8).
Le risque majeur de l'alcoolisation du septum proximal reĢside dans l'induction d'un bloc atrio-ventriculaire complet chimique, le noeud atrio-ventriculaire eĢtant justement situeĢ dans cette reĢgion. Ce risque augmente avec la quantiteĢ d'alcool administreĢe et neĢcessite, si persistance apreĢs trois jours, l'implantation d'un pacemaker aĢ demeure. Selon les centres, le taux d'implantation d'un stimulateur varie ainsi entre 7% et 20% (7,14,20).
L'efficaciteĢ clinique et l'incidence des complications est donc en partie lieĢe aĢ la compeĢtence technique et aĢ l'expeĢrience de l'opeĢrateur (7,14), mais aussi aux choix des patients. Il peut donc varier grandement selon les centres meĢdicaux.
L'eĢtude proposeĢe vise aĢ analyser les reĢsultats de l'alcoolisation obtenus aĢ Lausanne, jusqu'aĢ preĢsent pas encore eĢteĢ eĢtudieĢs, et aĢ les comparer aĢ ceux de la litteĢrature
Understanding future mode choice intentions of transit riders as a function of past experiences with travel quality
This paper empirically investigates the causes for transit use cessation, focusing on the influence of usersā personal experiences, resulting levels of satisfaction, and subsequent behavioral intentions. It builds on a novel data set in which observed, objective measures of travel times are mapped to smartphone-based surveys where participants assess their travel experience. An integrated choice and latent variable model is developed to explain the influence of satisfaction with operations (travel times) and satisfaction with the travel environment (e.g., crowding) on behavioral intentions. Satisfaction is modeled as a latent variable, and the choice consists of participantsā stated desire and intention to continue using public transportation. The results show how delays, in particular in-vehicle delays but also transfer times and being left behind at stops, contribute to passengersā intentions to cease transit use. Furthermore, a number of critical incidents, i.e., particularly memorable negative experiences, are found to have negative and significant effects on overall satisfaction and on willingness to continue using public transportation. The usefulness of the framework is demonstrated in a set of simulations in which the effect of three types of delays on passengersā willingness to remain transit riders is modeled. This work highlights the value and potential of using new data collection methods to gain insights on complex behavioral processes, and it is intended to form the basis for new modeling tools to understand the causes of transit use cessation and the impact of various strategies and service quality improvements to reduce ridership turnove
Weight perceptions of parents with children at risk for diabetes
BACKGROUND: The growing epidemic of obesity and diabetes among African American, Latino American, and Native American children in the United States has led to increasing focus on strategies for prevention. However, little is known about the perceptions toward weight, nutrition, and physical activity among these youth. This pilot study explored the perceptions of body weight among overweight and obese children and their parents. RESULTS: Thirty eight children, ages 8-16 years who were enrolled in a diabetes prevention study were surveyed to assess their perception of their weight. Nearly all (84%) of the children were obese. When asked whether they considered themselves to be overweight, African-American children were less likely to report that they were overweight than other children (33% vs. 80% of other children, p = 0.01). The parents of these children (n = 29) were also surveyed to assess their perception of their child's weight. The parents of two-thirds (65%) of the children reported that the child was overweight, while the rest reported their child was underweight or the right weight. African-American parents were less likely to report that their child's weight was unhealthy compared to other parents (46% vs. 77%, p = 0.069). CONCLUSIONS: This study's findings indicate that future intervention efforts should assess children's and parents' awareness of obesity and diabetes risk and these factors should be considered when developing prevention interventions for families with youth at risk for diabetes in underserved communities
360-degree Video Stitching for Dual-fisheye Lens Cameras Based On Rigid Moving Least Squares
Dual-fisheye lens cameras are becoming popular for 360-degree video capture,
especially for User-generated content (UGC), since they are affordable and
portable. Images generated by the dual-fisheye cameras have limited overlap and
hence require non-conventional stitching techniques to produce high-quality
360x180-degree panoramas. This paper introduces a novel method to align these
images using interpolation grids based on rigid moving least squares.
Furthermore, jitter is the critical issue arising when one applies the
image-based stitching algorithms to video. It stems from the unconstrained
movement of stitching boundary from one frame to another. Therefore, we also
propose a new algorithm to maintain the temporal coherence of stitching
boundary to provide jitter-free 360-degree videos. Results show that the method
proposed in this paper can produce higher quality stitched images and videos
than prior work.Comment: Preprint versio
Reliable Prediction of Insulin Resistance by a School-Based Fitness Test in Middle-School Children
Objectives. (1) Determine the predictive value of a school-based test of cardiovascular fitness (CVF) for insulin resistance (IR); (2) compare a āschool-basedā prediction of IR to a ālaboratory-basedā prediction, using various measures of fitness and body composition. Methods. Middle school children (n = 82) performed the Progressive Aerobic Cardiovascular Endurance Run (PACER), a school-based CVF test, and underwent evaluation of maximal oxygen consumption treadmill testing (VO2 max), body composition (percent body fat and BMI z score), and IR (derived homeostasis model assessment index
[HOMAIR]).
Results. PACER showed a strong correlation with VO2 max/kg (rs = 0.83, P < .001) and with HOMAIR (rs = ā0.60, P < .001). Multivariate regression analysis revealed that a school-based model (using PACER and BMI z score) predicted IR similar to a laboratory-based model (using VO2 max/kg of lean body mass and percent body fat). Conclusions. The PACER is a valid school-based test of CVF, is predictive of IR, and has a similar relationship to IR when compared to complex laboratory-based testing. Simple school-based measures of childhood fitness (PACER) and fatness (BMI z score) could be used to identify childhood risk for IR and evaluate interventions
Aprotinin reduces blood loss in off-pump coronary artery bypass (OPCAB) surgery
Objective: Effects of aprotinin in off-pump coronary artery bypass (OPCAB) surgery have not yet been described. This study analyses hemostasiologic changes and potential benefit in OPCAB patients treated with aprotinin. Methods: In a prospective, double-blind, randomized study 47 patients undergoing OPCAB surgery were investigated. Patients received either aprotinin (2Ć106 KIU loading dose and 0.5Ć106 KIU/h during surgery, n=22) or saline solution (control, n=25). Activated clotting time was adjusted to a target of 250 s intraoperatively. Blood samples were taken up to 18 h postoperatively: complete hematologic and hemostasiologic parameters including fibrinopeptide A (FPA) and D-dimer in a subgroup of 31 patients were analyzed. Blood loss, blood transfusion and other clinical data were collected. Results: Both groups showed comparable demographic and intraoperative variables. Forty-one (87%) patients of the whole study group received aspirin within 7 days prior to surgery. Number of grafts per patient were comparable (2.9Ā±1.0 [meanĀ±SD] in the aprotinin group and 2.8Ā±1.2 in control, P=0.83). Blood loss during the first 18 h in intensive care unit was significantly reduced in patients treated with aprotinin (median [25th-75th percentiles]: 500 [395-755] ml vs. 930 [800-1170] ml, P<0.001). Postoperatively only two patients (10%) in the aprotinin group received packed red blood cells, whereas eight (35%) in the control group (P=0.07). Perioperatively FPA levels reflecting thrombin generation were elevated in both groups. The increase in D-dimer levels after surgery was significantly inhibited in the aprotinin group (P<0.001). Early clinical outcome was similar in both groups. Conclusions: Aprotinin significantly reduces blood loss in patients undergoing OPCAB surgery. Inhibition of enhanced fibrinolysis can be observed. FPA generation during and after OPCAB surgery seems not to be influenced by aprotini
Respiratory Depression in Young Prader Willi Syndrome Patients following Clonidine Provocation for Growth Hormone Secretion Testing
Objectives. To determine the sedative and respiratory effects of clonidine when used to evaluate growth hormone (GH) secretion in children with
Prader Willi Syndrome (PWS). Methods. The study prospectively
evaluated children with PWS who received clonidine (0.15āmg/m2) to assess GH responsiveness. Patients were studied up to four
times over three years. Vital signs, oxygen saturation, and
sedation level were recorded at baseline and every five minutes
following clonidine. Changes between baseline and post-clonidine
were evaluated using a repeated measurement analysis.
Results. Sixty studies were performed on 17 patients, mean age 30.4 Ā± 15.0 months. The mean Ā± SD dose of clonidine was 0.074 Ā± 0.027āmg (5.3 Ā± 1.72āmcg/kg). All patients achieved a sedation score of 4 to 5 (drowsy to asleep). Mean declines in respiratory rate (7.5 Ā± 6.1 breaths/min; P < .001), and oxygen saturation (2.2 Ā± 2.0%; P < .001) occurred following clonidine. Five patients (29%) experienced oxygen saturations
ā¤94% on nine occasions. Three oxygen desaturations were accompanied by partial airway obstruction. Conclusions. Clonidine doses to assess GH secretion often exceed doses used for sedation and result in significant respiratory depression in some children with PWS. There was no association between oxygen desaturation and BMI
Aprotinin reduces blood loss in off-pump coronary artery bypass (OPCAB) surgery
Objective: Effects of aprotinin in off-pump coronary artery bypass (OPCAB) surgery have not yet been described. This study analyses hemostasiologic changes and potential benefit in OPCAB patients treated with aprotinin. Methods: In a prospective, double-blind, randomized study 47 patients undergoing OPCAB surgery were investigated. Patients received either aprotinin (2Ć10 superscript 6 KIU loading dose and 0.5Ć10 superscript 6 KIU/h during surgery, n=22) or saline solution (control, n=25). Activated clotting time was adjusted to a target of 250 s intraoperatively. Blood samples were taken up to 18 h postoperatively: complete hematologic and hemostasiologic parameters including fibrinopeptide A (FPA) and D-dimer in a subgroup of 31 patients were analyzed. Blood loss, blood transfusion and other clinical data were collected. Results: Both groups showed comparable demographic and intraoperative variables. Forty-one (87%) patients of the whole study group received aspirin within 7 days prior to surgery. Number of grafts per patient were comparable (2.9Ā±1.0 [meanĀ±SD] in the aprotinin group and 2.8Ā±1.2 in control, P=0.83). Blood loss during the first 18 h in intensive care unit was significantly reduced in patients treated with aprotinin (median [25thā75th percentiles]: 500 [395ā755] ml vs. 930 [800ā1170] ml, P<0.001). Postoperatively only two patients (10%) in the aprotinin group received packed red blood cells, whereas eight (35%) in the control group (P=0.07). Perioperatively FPA levels reflecting thrombin generation were elevated in both groups. The increase in D-dimer levels after surgery was significantly inhibited in the aprotinin group (P<0.001). Early clinical outcome was similar in both groups. Conclusions: Aprotinin significantly reduces blood loss in patients undergoing OPCAB surgery. Inhibition of enhanced fibrinolysis can be observed. FPA generation during and after OPCAB surgery seems not to be influenced by aprotinin
Transplantation of a Human Mammary Carcinoma Cell Line (BT 20) Into Nude Mice
Cell suspensions of a human mammary carcinoma cell line (BT 20), when injected subcutaneously into nude athymic mice (BALB/c Nu/Nu), produced tumor nodules at the injection site. Subsequent serial transplantations also gave rise to neoplastic nodules after latency periods averaging 3 weeks. The nodules displayed morphologic and functional characteristics comparable to those of the original tumor cells. Metastases, however, were not observed in any of the tumor-bearing mic
Environment and Obesity in the National Children\u27s Study
Objective: In this review we describe the approach taken by the National Childrenās Study (NCS), a 21-year prospective study of 100,000 American children, to understanding the role of environmental factors in the development of obesity.
Data sources and extraction: We review the literature with regard to the two core hypotheses in the NCS that relate to environmental origins of obesity and describe strategies that will be used to test each hypothesis.
Data synthesis: Although it is clear that obesity in an individual results from an imbalance between energy intake and expenditure, control of the obesity epidemic will require understanding of factors in the modern built environment and chemical exposures that may have the capacity to disrupt the link between energy intake and expenditure. The NCS is the largest prospective birth cohort study ever undertaken in the United States that is explicitly designed to seek information on the environmental causes of pediatric disease.
Conclusions: Through its embrace of the life-course approach to epidemiology, the NCS will be able to study the origins of obesity from preconception through late adolescence, including factors ranging from genetic inheritance to individual behaviors to the social, built, and natural environment and chemical exposures. It will have sufficient statistical power to examine interactions among these multiple influences, including geneāenvironment and geneāobesity interactions. A major secondary benefit will derive from the banking of specimens for future analysis
- ā¦