Right Ventricle Stress Test (RiVeS Test) un nouvel outil pour l’évaluation de la réserve fonctionnelle du ventricule droit dans l’insuffisance cardiaque terminale

Connaissances actuelles : En Suisse, l’insuffisance cardiaque touche 8'000 à 13'000 personnes par année. Les coûts annuels estimés que cette unique pathologie sont de 200 millions de francs suisses. La transplantation cardiaque a longtemps été l’unique traitement pour les patients souffrant d’insuffisance cardiaque terminale, mais le faible nombre de donneurs ainsi que le nombre restreint de patients étant capables de supporter une telle opération limite passablement son application. Heureusement, depuis 1991 il existe l’assistance ventriculaire gauche qui constitue la principale alternative à la transplantation cardiaque. L’évaluation fonctionelle du ventricule droit est cruciale dans le choix du traitement des patients en insuffisance cardiaque terminale. Une bonne réserve fonctionnelle nous dirige vers l’implantation d’une assistance ventriculaire gauche seule, or une mauvaise réserve fonctionnelle du ventricule droit nécessite une assistance ventriculaire droite d’emblée. Une erreur de décision clinique engendre une morbidité et une mortalité accrue. Malheureusement, le manque de méthodes efficaces pour prédire l’insuffisance cardiaque droite survenant après l’impantation d’assistance ventriculaire gauche, augmente le risque d’erreur de décision clinique. Actuellement l’évaluation du ventricule droit se fait à l’aide de scores cliniques ainsi que différentes méthodes échocardiographiques. Cependant, plusieurs études montrent que ces méthodes ont une modeste valeur de prédiction d’une insuffisance ventriculaire droite. Objectif : Notre but est de mettre au point le premier test d’effort spécifique au ventricule droit, permettant de quantifier la réserver fonctionnelle de ce dernier. Ce stress test prendra le nom de Right Ventricle Stress Test (RiVeS Test). Ce travail porte sur l’étude de faisabilité du RiveS test. L’objectif de ce travail, est non seulement d’essayer de prouver que l’inhalation progressive de CO2 induit un stress sur le ventricule droit mais aussi de confirmer que la méthode est sûre et bien tolérée. Méthode : L’étude de faisabilité consiste à induire un stress sur le ventricule droit sur cinq volontaires sains. Ceci par augmentation de la post-charge par le biais d’inhalation progressive de CO2; puis d’évaluer les changements morphologiques et de la fonction contractile du ventricule droit induits par ce stress à l’aide de l’echocardiographie trans-thoracique. Du point de vue de l’analyse des résultats, nous avons utilisé le test de student afin d’apprécier la valeur significative de l’augmentation de la PCO2 avant et en fin de test. Résultats : Trois des cinq volontaires étaient porteurs d’une insuffisance tricuspidienne et ont ainsi permis la mesure de l’augmentation de la pression artérielle pulmonaire (PAP) durant le test. Ces mesures ont conduit à la réalisation de courbes doses/réponses (c’est-à-dire PAP en fonction de la PCO2) qui sont très différentes d’une personne à l’autre. Le test de Student nous a permis d’affirmer que l’augmentation de la PCO2 induite par le test était statistiquement significative. D’autres paramètres échocardiographiques tels que la TAPSE (tricuspid annular plane systolic excursion) et la RVFAC (right ventricle fractional area change) ont pu être mesurés et montrent également des profils induits par le test qui sont très hétérogènes entres les volontaires. 3 Conclusion : Ce travail a permis de démontrer que l’inhalation de CO2 est une méthode sûre et bien tolérée. Les résultats obtenus sont encourageants puisque nous avons pu mesurer des changements fonctionnels du ventricule droit. Le RiVeS test induit ainsi, très probablement, un stress sur le ventricule droit. Ceci mériterait cependant d’être confirmé par IRM cardiaque. Enfin, ce travail a permis de mettre en lumière l’intérêt et l’utilité que le RiVeS test pourrait avoir dans la prise en charge des patients en insuffisance cardiaque terminale. Non seulement il permettra une évaluation de la réserve fonctionnelle du ventricule droit mais surtout il nous aidera dans le choix de traitement le plus adapté au patient

Alopecia areata is characterized by dysregulation in systemic type 17 and type 2 cytokines, which may contribute to disease‐associated psychological morbidity

Background: Alopecia areata (AA) is a common autoimmune disease, causing patchy hair loss that can progress to involve the entire scalp (totalis) or body (universalis). CD8+NKG2D+ T cells dominate hair follicle pathogenesis, but the specific mechanisms driving hair loss are not fully understood. Objectives To provide a detailed insight into the systemic cytokine signature associated with AA, and assess the association between cytokines and depression. Methods: Multiplex analysis of plasma cytokines from AA patients, psoriatic arthritis (PsA) patients and healthy controls. We also assessed incidence of depression and anxiety using the Hospital Anxiety and Depression Scale. Results: Our analysis identified a systemic inflammatory signature associated with AA, characterised by elevated levels of IL-17A, IL-17F, IL-21 and IL-23 indicative of a type 17 immune response. Circulating levels of the type 2 cytokines IL-33, IL-31 and IL-17E/25 are also significantly increased in AA. In comparison to PsA, AA was associated with higher levels of IL-17F, IL-17E and IL-23. We hypothesised that circulating inflammatory cytokines may contribute to wider comorbidities associated with AA. We assessed psychiatric comorbidity in AA using the Hospital Anxiety and Depression Scale and found that 18% and 51% of people with AA experienced symptoms of depression and anxiety, respectively. Using linear regression modelling, we identified that levels of IL-22 and IL-17E are positively and significantly associated with depression. Conclusion: Our data highlight changes in both type 17 and 2 cytokines, suggesting that complex systemic cytokine profiles may contribute both to the pathogenesis of AA and to the associated depression

Occupational and leisure time physical activity in contrasting relation to ambulatory blood pressure

Background: While moderate and vigorous leisure time physical activities are well documented to decrease the risk for cardiovascular disease, several studies have demonstrated an increased risk for cardiovascular disease in workers with high occupational activity. Research on the underlying causes to the contrasting effects of occupational and leisure time physical activity on cardiovascular health is lacking. The aim of this study was to examine the relation of objective and self-report measures of occupational and leisure time physical activity with 24-h ambulatory systolic blood pressure (BP). Methods: Results for self-reported physical activity are based on observations in 182 workers (60% male, mean age 51 years), while valid objective physical activity data were available in 151 participants. The usual level of physical activity was assessed by 5 items from the Job Content Questionnaire (high physical effort, lifting heavy loads, rapid physical activity, awkward body positions and awkward positions of head or arms at work) and one item asking about the general level of physical activity during non-working time. On a regular working day, participants wore an ambulatory BP monitor and an accelerometer physical activity monitor during 24 h. Associations were examined by means of Analysis of Covariance. Results: Workers with an overall high level of self-reported occupational physical activity as well as those who reported to often lift heavy loads at work had a higher mean systolic BP at work, at home and during sleep. However, no associations were observed between objectively measured occupational physical activity and BP. In contrast, those with objectively measured high proportion of moderate and vigorous leisure time physical activity had a significantly lower mean systolic BP during daytime, while no differences were observed according to self-reported level of leisure time physical activity. Conclusions: These findings suggest that workers reporting static occupational physical activities, unlike general physically demanding tasks characterized by dynamic movements of large muscle groups, are related to a higher daily systolic BP, while high objective levels of moderate and vigorous leisure time physical activity are related to lower daytime systolic BP. Ambulatory systolic BP may be a physiological explanatory factor for the contrasting effects of occupational and leisure time physical activity

The point of maximum curvature as a marker for physiological time series

We present a geometric analysis of the model of Stirling. In particular we analyze the curvature of a heart rate time series in response to a step like increment in the exercise intensity. We present solutions for the point of maximum curvature which can be used as a marker of physiological interest. This marker defines the point after which the heart rate no longer continues to rapidly rise and instead follows either a steady state or slow rise. These methods are then applied to find analytic solutions for a mono exponential model which is commonly used in the literature to model the response to a moderate exercise intensity. Numerical solutions are then found for the full model and parameter values presented in Stirling

Marginalization of end-use technologies in energy innovation for climate protection

Mitigating climate change requires directed innovation efforts to develop and deploy energy technologies. Innovation activities are directed towards the outcome of climate protection by public institutions, policies and resources that in turn shape market behaviour. We analyse diverse indicators of activity throughout the innovation system to assess these efforts. We find efficient end-use technologies contribute large potential emission reductions and provide higher social returns on investment than energy-supply technologies. Yet public institutions, policies and financial resources pervasively privilege energy-supply technologies. Directed innovation efforts are strikingly misaligned with the needs of an emissions-constrained world. Significantly greater effort is needed to develop the full potential of efficient end-use technologies

Constructing an index of physical fitness age for Japanese elderly based on 7-year longitudinal data: sex differences in estimated physical fitness age

A standardized method for assessing the physical fitness of elderly adults has not yet been established. In this study, we developed an index of physical fitness age (fitness age score, FAS) for older Japanese adults and investigated sex differences based on the estimated FAS. Healthy elderly adults (52 men, 70 women) who underwent physical fitness tests once yearly for 7 years between 2002 and 2008 were included in this study. The age of the participants at the beginning of this study ranged from 60.0 to 83.0 years. The physical fitness tests consisted of 13 items to measure balance, agility, flexibility, muscle strength, and endurance. Three criteria were used to evaluate fitness markers of aging: (1) significant cross-sectional correlation with age; (2) significant longitudinal change with age consistent with the cross-sectional correlation; and (3) significant stability of individual differences. We developed an equation to assess individual FAS values using the first principal component derived from principal component analysis. Five candidate fitness markers of aging (10-m walking time, functional reach, one leg stand with eyes open, vertical jump and grip strength) were selected from the 13 physical fitness tests. Individual FAS was predicted from these five fitness markers using a principal component model. Individual FAS showed high longitudinal stability for age-related changes. This investigation of the longitudinal changes of individual FAS revealed that women had relatively lower physical fitness compared with men, but their rate of physical fitness aging was slower than that of men

Effects of Aging on the Biomechanics of Slips and Falls

Although much has been learned in recent decades about the deterioration of muscular strength, gait adaptations, and sensory degradation among older adults, little is known about how these intrinsic changes affect biomechanical parameters associated with slip-induced fall accidents. In general, the objective of this laboratory study was to investigate the process of initiation, detection, and recovery of inadvertent slips and falls. We examined the initiation of and recovery from foot slips among three age groups utilizing biomechanical parameters, muscle strength, and sensory measurements. Forty-two young, middle-age, and older participants walked around a walking track at a comfortable pace. Slippery floor surfaces were placed on the track over force platforms at random intervals without the participants’ awareness. Results indicated that younger participants slipped as often as the older participants, suggesting that the likelihood of slip initiation is similar across all age groups; however, older individuals’ recovery process was much slower and less effective. The ability to successfully recover from a slip (thus preventing a fall) is believed to be affected by lower extremity muscle strength and sensory degradation among older individuals. Results from this research can help pinpoint possible intervention strategies for improving dynamic equilibrium among older adults

Modeling Molecular Interactions in Water: From Pairwise to Many-Body Potential Energy Functions.

Almost 50 years have passed from the first computer simulations of water, and a large number of molecular models have been proposed since then to elucidate the unique behavior of water across different phases. In this article, we review the recent progress in the development of analytical potential energy functions that aim at correctly representing many-body effects. Starting from the many-body expansion of the interaction energy, specific focus is on different classes of potential energy functions built upon a hierarchy of approximations and on their ability to accurately reproduce reference data obtained from state-of-the-art electronic structure calculations and experimental measurements. We show that most recent potential energy functions, which include explicit short-range representations of two-body and three-body effects along with a physically correct description of many-body effects at all distances, predict the properties of water from the gas to the condensed phase with unprecedented accuracy, thus opening the door to the long-sought "universal model" capable of describing the behavior of water under different conditions and in different environments

Static and Dynamic Lung Volumes in Swimmers and Their Ventilatory Response to Maximal Exercise

Purpose While the static and dynamic lung volumes of active swimmers is often greater than the predicted volume of similarly active non-swimmers, little is known if their ventilatory response to exercise is also different. Methods Three groups of anthropometrically matched male adults were recruited, daily active swimmers (n = 15), daily active in fields sport (Rugby and Football) (n = 15), and recreationally active (n = 15). Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal voluntary ventilation (MVV) was measured before and after exercise to volitional exhaustion. Results Swimmers had significantly larger FVC (6.2 ± 0.6 l, 109 ± 9% pred) than the other groups (5.6 ± 0.5 l, 106 ± 13% pred, 5.5 ± 0.8, 99% pred, the sportsmen and recreational groups, respectively). FEV1 and MVV were not different. While at peak exercise, all groups reached their ventilatory reserve (around 20%), the swimmers had a greater minute ventilation rate than the recreational group (146 ± 19 vs 120 ± 87 l/min), delivering this volume by breathing deeper and slower. Conclusions The swimmers utilised their larger static volumes (FVC) differently during exercise by meeting their ventilation volume through long and deep breaths