Fitness, sport et pression artérielle [Fitness, sports and blood pressure].

Blood pressure is lowered for a few hours after aerobic exercise, but also after resistance exercise, although for a shorter period of time. An exercise program can significantly lower resting and ambulatory BP measurements. Multiple mechanisms interact for the BP lowering effect, such as decreased total peripheral resistance, enhanced endothelial function, diminished sympathetic or rennin plasmatic activity, structural vascular modifications and baroreceptor reflex modulation. New exercises like eccentric or isometric (handgrip) contractions are promising. Resistance activities have long been considered dangerous for blood vessels because of increased arterial stiffness, but if the intensity remains moderate and aerobic exercises are integrated, then the effects are altogether beneficial.

Structural alterations of the coronary arterial wall are associated with myocardial flow heterogeneity in type 2 diabetes mellitus.

PURPOSE: To determine the relationship between carotid intima-media thickness (IMT), coronary artery calcification (CAC), and myocardial blood flow (MBF) at rest and during vasomotor stress in type 2 diabetes mellitus (DM). METHODS: In 68 individuals, carotid IMT was measured using high-resolution vascular ultrasound, while the presence of CAC was determined with electron beam tomography (EBT). Global and regional MBF was determined in milliliters per gram per minute with (13)N-ammonia and positron emission tomography (PET) at rest, during cold pressor testing (CPT), and during adenosine (ADO) stimulation. RESULTS: There was neither a relationship between carotid IMT and CAC (r = 0.10, p = 0.32) nor between carotid IMT and coronary circulatory function in response to CPT and during ADO (r = -0.18, p = 0.25 and r = 0.10, p = 0.54, respectively). In 33 individuals, EBT detected CAC with a mean Agatston-derived calcium score of 44 +/- 18. There was a significant difference in regional MBFs between territories with and without CAC at rest and during ADO-stimulated hyperemia (0.69 +/- 0.24 vs. 0.74 +/- 0.23 and 1.82 +/- 0.50 vs. 1.95 +/- 0.51 ml/g/min; p < or = 0.05, respectively) and also during CPT in DM but less pronounced (0.81 +/- 0.24 vs. 0.83 +/- 0.23 ml/g/min; p = ns). The increase in CAC was paralleled with a progressive regional decrease in resting as well as in CPT- and ADO-related MBFs (r = -0.36, p < or = 0.014; r = -0.46, p < or = 0.007; and r = -0.33, p < or = 0.041, respectively). CONCLUSIONS: The absence of any correlation between carotid IMT and coronary circulatory function in type 2 DM suggests different features and stages of early atherosclerosis in the peripheral and coronary circulation. PET-measured MBF heterogeneity at rest and during vasomotor stress may reflect downstream fluid dynamic effects of coronary artery disease (CAD)-related early structural alterations of the arterial wall.

Neuroplasticity of inhibitory control

Executive control refers to a set of abilities enabling us to plan, control and implement our behavior to rapidly and flexibly adapt to environmental requirements. These adaptations notably involve the suppression of intended or ongoing cognitive or motor processes, a skill referred to as "inhibitory control". To implement efficient executive control of behavior, one must monitor our performance following errors to adjust our behavior accordingly. Deficits in inhibitory control have been associated with the emergènce of a wide range of psychiatric disorders, ranging from drug addiction to attention deficit/hyperactivity disorders. Inhibitory control deficits could, however, be remediated- The brain has indeed the amazing possibility to reorganize following training to allow for behavioral improvements. This mechanism is referred to as neural and behavioral plasticity. Here, our aim is to investigate training-induced plasticity in inhibitory control and propose a model of inhibitory control explaining the spatio- temporal brain mechanisms supporting inhibitory control processes and their plasticity. In the two studies entitled "Brain dynamics underlying training-induced improvement in suppressing inappropriate action" (Manuel et al., 2010) and "Training-induced neuroplastic reinforcement óf top-down inhibitory control" (Manuel et al., 2012c), we investigated the neurophysiological and behavioral changes induced by inhibitory control training with two different tasks and populations of healthy participants. We report that different inhibitory control training developed either automatic/bottom-up inhibition in parietal areas or reinforced controlled/top-down inhibitory control in frontal brain regions. We discuss the results of both studies in the light of a model of fronto-basal inhibition processes. In "Spatio-temporal brain dynamics mediating post-error behavioral adjustments" (Manuel et al., 2012a), we investigated how error detection modulates the processing of following stimuli and in turn impact behavior. We showed that during early integration of stimuli, the activity of prefrontal and parietal areas is modulated according to previous performance and impacts the post-error behavioral adjustments. We discuss these results in terms of a shift from an automatic to a controlled form of inhibition induced by the detection of errors, which in turn influenced response speed. In "Inter- and intra-hemispheric dissociations in ideomotor apraxia: a large-scale lesion- symptom mapping study in subacute brain-damaged patients" (Manuel et al., 2012b), we investigated ideomotor apraxia, a deficit in performing pantomime gestures of object use, and identified the anatomical correlates of distinct ideomotor apraxia error types in 150 subacute brain-damaged patients. Our results reveal a left intra-hemispheric dissociation for different pantomime error types, but with an unspecific role for inferior frontal areas. Les fonctions exécutives désignent un ensemble de processus nous permettant de planifier et contrôler notre comportement afin de nous adapter de manière rapide et flexible à l'environnement. L'une des manières de s'adapter consiste à arrêter un processus cognitif ou moteur en cours ; le contrôle de l'inhibition. Afin que le contrôle exécutif soit optimal il est nécessaire d'ajuster notre comportement après avoir fait des erreurs. Les déficits du contrôle de l'inhibition sont à l'origine de divers troubles psychiatriques tels que l'addiction à la drogue ou les déficits d'attention et d'hyperactivité. De tels déficits pourraient être réhabilités. En effet, le cerveau a l'incroyable capacité de se réorganiser après un entraînement et ainsi engendrer des améliorations comportementales. Ce mécanisme s'appelle la plasticité neuronale et comportementale. Ici, notre but èst d'étudier la plasticité du contrôle de l'inhibition après un bref entraînement et de proposer un modèle du contrôle de l'inhibition qui permette d'expliquer les mécanismes cérébraux spatiaux-temporels sous-tendant l'amélioration du contrôle de l'inhibition et de leur plasticité. Dans les deux études intitulées "Brain dynamics underlying training-induced improvement in suppressing inappropriate action" (Manuel et al., 2010) et "Training-induced neuroplastic reinforcement of top-down inhibitory control" (Manuel et al., 2012c), nous nous sommes intéressés aux changements neurophysiologiques et comportementaux liés à un entraînement du contrôle de l'inhibition. Pour ce faire, nous avons étudié l'inhibition à l'aide de deux différentes tâches et deux populations de sujets sains. Nous avons démontré que différents entraînements pouvaient soit développer une inhibition automatique/bottom-up dans les aires pariétales soit renforcer une inhibition contrôlée/top-down dans les aires frontales. Nous discutons ces résultats dans le contexte du modèle fronto-basal du contrôle de l'inhibition. Dans "Spatio-temporal brain dynamics mediating post-error behavioral adjustments" (Manuel et al., 2012a), nous avons investigué comment la détection d'erreurs influençait le traitement du prochain stimulus et comment elle agissait sur le comportement post-erreur. Nous avons montré que pendant l'intégration précoce des stimuli, l'activité des aires préfrontales et pariétales était modulée en fonction de la performance précédente et avait un impact sur les ajustements post-erreur. Nous proposons que la détection d'erreur ait induit un « shift » d'un mode d'inhibition automatique à un mode contrôlé qui a à son tour influencé le temps de réponse. Dans "Inter- and intra-hemispheric dissociations in ideomotor apraxia: a large-scale lesion-symptom mapping study in subacute brain-damaged patients" (Manuel et al., 2012b), nous avons examiné l'apraxie idémotrice, une incapacité à exécuter des gestes d'utilisation d'objets, chez 150 patients cérébro-lésés. Nous avons mis en avant une dissociation intra-hémisphérique pour différents types d'erreurs avec un rôle non spécifique pour les aires frontales inférieures.

The neuronal adhesion protein D2 in differentiating aggregates of brain cells.

The D2-protein is a high molecular weight protein involved in interneuronal adhesion. The concentration of D2-protein was measured both in aggregates of fetal rat telencephalic cells cultured in a chemically defined medium and in developing forebrain. Both the concentration of the D2-protein and the degree of sialylation were changed in the cultures in parallel with the corresponding values obtained from postnatal forebrain. In the cultures the highest specific concentration of D2-protein was observed after 12 days in culture. This value was 2.7 times higher than the average value of adult rat forebrain. Antibodies to D2-protein have previously been shown to inhibit fasciculation of neuritic fibers extending from cultured explants of sympathetic ganglia. We investigated the effect of such antibodies on the differentiation of aggregating telencephalic cells. By adding surplus antibodies to the cultures from day 11 to day 16 we were able to decrease the specific concentration of D2-protein on the neurons by 53% measured at day 19. The decrease was not compensated fully even after further 10 days in the culture. Although the concentration of D2-protein was decreased during the period of synaptogenesis no change was found in the specific concentration of a marker of mature synapses, the D3-protein. Thus, in this culture system synaptogenesis could proceed to an unimpaired extent in the presence of a decreased concentration of a putatively involved adhesion molecule. However, the specific concentration of two markers of myelination, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin basic protein, were both increased, suggesting an antibody-induced stimulation of myelination in the cultured aggregates.

Effect of the September 11, 2001 terrorist attack on a state highway patrol trooper's heart rate variability

BACKGROUND: On September 11, 2001, terrorists attacked the United States. By coincidence, a North Carolina highway patrol trooper was wearing an ambulatory ECG Holter monitor at this time as part of an air pollution study. METHODS: Heart rate variability parameters were analyzed: standard deviation of normal to normal beat intervals (SDNN) and percentage of interval differences >50 ms (PNN50). RESULTS: The trooper's heart rate variability changed immediately after learning about the terrorist attacks. Heart rate increased and PNN50 decreased, while SDNN increased strongly. CONCLUSIONS: These changes suggest strong emotional sympathetic stress associated with parasympathetic withdrawal in response to the news about the terrorist attack. [Authors]

Cardiovascular patterns associated with appetitive and defensive activation during affective picture viewing

Descriptors: cardiovascular patterns, emotion, affective pictures In this study we assessed blood pressure (BP), heart rate (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) in response to 13 picture series in 18 men and 19 women in order to investigate their hemodynamic responses associated with activation of the appetitive and defensive motivational systems underlying emotional experience. Skin conductance level (SCL) was also recorded. BP and SV increased with increasing self-rated arousal both for appetitive and defensive activation, whereas HR decelerated more in response to negative than positive and neutral pictures. TPR showed a general increase from baseline to picture processing but was unrelated to self-rated valence and arousal. These findings suggest that affective modulation of the cardiovascular response to affective pictures is primarily myocardial. The observed response pattern is consistent with a configuration of cardiac sympathetic-parasympathetic coactivation. The relationships between self-reported arousal, BP and SV were mainly exhibited by men suggesting that increases in the sympathetic inotropic effect to the heart with increasing self-rated arousal might be larger in men than in women. In contrast, SCL covaried positively with self-rated arousal both in men and women. This suggests that sex differences in the affective modulation of the responses to pictures may be restricted to specific cardiovascular parameters and support the contention that the sympathetic nervous system does not discharge as a whole.

Augmented myocardial methionine-enkephalin in a murine model of cardiac angiotensin II-overexpression.

INTRODUCTION: The endogenous opioid system has been reported to interact with both the cardiac sympathetic and renin-angiotensin systems in exerting a local regulatory action on the heart. The goal of this investigation was to examine how cardiac levels of enkephalin production are altered in the development of normotensive primary hypertrophy due to elevated intra-cardiac angiotensin II (Ang II) production. METHODS: Atrial and ventricular methionine-enkephalin (ME) levels were measured by quantitative radioimmunoassay in 14 and 28-week-old male transgenic mice (TG1306/1R) and control mice. The TG1306/1R exhibit cardiac specific Ang II overexpression and cardiac hypertrophy, but not hypertension. RESULTS: TG1306/1R mice had significantly higher heart/body weight ratios (15-20%) than control littermates at both 14 (p=0.02) and 28 weeks (p=0.04). Relative to controls, ME content was significantly elevated (approximately two-fold) in atria and ventricles in the older 28-week TG1306/1R mice only. A significant inverse correlation between heart size and ME level was observed for 28-week TG1306/1R only. CONCLUSIONS: We have provided evidence that a marked elevation of myocardial enkephalin level is observed in the established (but not early) phase of cardiac hypertrophy associated with cardiac-specific Ang II-overexpression. This study identifies a potentially important relationship between two endogenous peptidergic signalling systems involved in the regulation of growth and function of the hypertrophic heart.

Risk factors of obesity and their determinants in preschool children (the Swiss Ballabeina study)

This thesis has been conducted in the context of a lifestyle intervention in 40 Swiss kindergarten classes in the cantons St. Gallen and Vaud, in areas with a high migrant prevalence (Ballabeina study). The main objective of this work was to fill certain gaps of the literature and to bring a better understanding of the risk factors of overweight and obesity and their determinants in preschool children. Our data show that parental migrant status and educational level influence independently of each other adiposity and/or eating habits in these children. In addition, sports club participation at this young age seems to be a better indicator of healthy lifestyle characteristics in terms of physical activity, sedentary behaviour and eating habits than weight status. Finally, we found that in this population higher scores of hyperactivity/inattention are associated with lower adiposity and with both healthy (more physical activity and less sedentary activity) and unhealthy (more television viewing and more unhealthy eating habits) lifestyle characteristics. Thus, our findings can be used by different actors of health and education system to better target their preventive actions and can serve as a basis for future complementary researches. - Cette thèse a été réalisée dans le cadre d'un projet de promotion de la santé mené dans 40 classes enfantines suisses issues de régions à forte prévalence migrante des cantons de St. Gall et de Vaud (étude Ballabeina). L'objectif principal de ce travail était de combler certaines lacunes de la littérature et d'approfondir nos connaissances sur les facteurs de risque du surpoids et de l'obésité et de leurs déterminants chez les enfants d'âge préscolaire. Nos analyses montrent que le statut de migrant des parents et leur niveau d'éducation influencent indépendamment l'un de l'autres l'adiposité et les habitudes alimentaires chez ces enfants. De plus, à ce jeune âge la participation dans un club de sport semble être un meilleur indicateur de style de vie sain en termes d'activité physique, de comportements sédentaires et d'habitudes alimentaires que le statut pondéral. Nous avons également trouvé que dans cette population, un score plus élevé d'hyperactivité/inattention est associé aussi bien à des caractéristiques de style de vie saines (plus d'activité physique, moins d'activité sédentaire) que malsaines (plus de consommation de télévision et moins bonnes habitudes alimentaire. Ainsi, nos résultats peuvent aider les différents acteurs de la santé et de l'éducation à mieux cibler leurs actions de prévention et servir de base à de futures recherches complémentaires.

Renal and neurohormonal responses to increasing levels of lower body negative pressure in men.

BACKGROUND: The stimulation of efferent renal sympathetic nerve activity induces sequential changes in renin secretion, sodium excretion, and renal hemodynamics that are proportional to the magnitude of the stimulation of sympathetic nerves. This study in men investigated the sequence of the changes in proximal and distal renal sodium handling, renal and systemic hemodynamics, as well as the hormonal profile occurring during a sustained activation of the sympathetic nervous system induced by various levels of lower body negative pressure (LBNP). METHODS: Ten healthy subjects were submitted to three levels of LBNP ranging between 0 and -22.5 mm Hg for one hour according to a triple crossover design, with a minimum of five days between each level of LBNP. Systemic and renal hemodynamics, renal water and sodium handling (using the endogenous lithium clearance technique), and the neurohormonal profile were measured before, during, and after LBNP. RESULTS: LBNP (0 to -22.5 mm Hg) induced an important hormonal response characterized by a significant stimulation of the sympathetic nervous system and gradual activations of the vasopressin and the renin-angiotensin systems. LBNP also gradually reduced water excretion and increased urinary osmolality. A significant decrease in sodium excretion was apparent only at -22.5 mm Hg. It was independent of any change in the glomerular filtration rate and was mediated essentially by an increased sodium reabsorption in the proximal tubule (a significant decrease in lithium clearance, P < 0.05). No significant change in renal hemodynamics was found at the tested levels of LBNP. As observed experimentally, there appeared to be a clear sequence of responses to LBNP, the neurohormonal response occurring before the changes in water and sodium excretion, these latter preceding any change in renal hemodynamics. CONCLUSIONS: These data show that the renal sodium retention developing during LBNP, and thus sympathetic nervous stimulation, is due mainly to an increase in sodium reabsorption by the proximal segments of the nephron. Our results in humans also confirm that, depending on its magnitude, LBNP leads to a step-by-step activation of neurohormonal, renal tubular, and renal hemodynamic responses.

Cardiovascular patterns associated with appetitive and defensive activation during affective picture viewing

In this study we assessed blood pressure (BP), heart rate (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) in response to 13 picture series in 37 participants in order to investigate their hemodynamic response associated with activation of the appetitive and defensive motivational systems underlying emotional experience. BP and SV, but not TPR, increased with increasing self-rated arousal, whereas HR decelerated more in response to negative than positive and neutral pictures. These findings suggest that modulation of the cardiovascular response to pictures is primarily myocardial. The observed response pattern is consistent with a configuration of cardiac sympathetic-parasympathetic coactivation. The relationships between self-rated arousal, BP, and SV were mainly exhibited by men, suggesting that increases in the sympathetic inotropic effect to the heart with self-rated arousal may be larger in men than in women.

Concomitant calcium entry blockade and inhibition of the renin-angiotensin system: a rational and effective means for treating hypertension

Pharmacological treatment of hypertension is effective in preventing cardiovascular and renal complications. Calcium antagonists (CAs) and blockers of the renin-angiotensin system [angiotensin-converting enzyme (ACE) inhibitors and angiotensin II antagonists (ARBs)] are widely used today to initiate antihypertensive treatment but, when given as monotherapy, do not suffice in most patients to normalise blood pressure (BP). Combining a CA and either an ACE-inhibitor or an ARB considerably increases the antihypertensive efficacy, but not at the expense of a deterioration of tolerability. Several fixed-dose combinations are available (CA + ACE-inhibitors: amlodipine + benazepril, felodipine + ramipril, verapamil + trandolapril; CA + ARB: amlodipine + valsartan). They are expected not only to improve BP control, but also to facilitate long-term adherence with antihypertensive therapy, thereby providing maximal protection against the cardiovascular and renal damage caused by high BP.

Influence of a lifestyle intervention in preschool children on physiological and psychological parameters (Ballabeina): study design of a cluster randomized controlled trial.

Childhood obesity and physical inactivity are increasing dramatically worldwide. Children of low socioeconomic status and/or children of migrant background are especially at risk. In general, the overall effectiveness of school-based programs on health-related outcomes has been disappointing. A special gap exists for younger children and in high risk groups. This paper describes the rationale, design, curriculum, and evaluation of a multicenter preschool randomized intervention study conducted in areas with a high migrant population in two out of 26 Swiss cantons. Twenty preschool classes in the German (canton St. Gallen) and another 20 in the French (canton Vaud) part of Switzerland were separately selected and randomized to an intervention and a control arm by the use of opaque envelopes. The multidisciplinary lifestyle intervention aimed to increase physical activity and sleep duration, to reinforce healthy nutrition and eating behaviour, and to reduce media use. According to the ecological model, it included children, their parents and the teachers. The regular teachers performed the majority of the intervention and were supported by a local health promoter. The intervention included physical activity lessons, adaptation of the built infrastructure; promotion of regional extracurricular physical activity; playful lessons about nutrition, media use and sleep, funny homework cards and information materials for teachers and parents. It lasted one school year. Baseline and post-intervention evaluations were performed in both arms. Primary outcome measures included BMI and aerobic fitness (20 m shuttle run test). Secondary outcomes included total (skinfolds, bioelectrical impedance) and central (waist circumference) body fat, motor abilities (obstacle course, static and dynamic balance), physical activity and sleep duration (accelerometry and questionnaires), nutritional behaviour and food intake, media use, quality of life and signs of hyperactivity (questionnaires), attention and spatial working memory ability (two validated tests). Researchers were blinded to group allocation. The purpose of this paper is to outline the design of a school-based multicenter cluster randomized, controlled trial aiming to reduce body mass index and to increase aerobic fitness in preschool children in culturally different parts of Switzerland with a high migrant population. Trial Registration: (clinicaltrials.gov) NCT00674544.

Stimulation by leptin of 3H GDP binding to brown adipose tissue of fasted but not fed rats.

OBJECTIVES: To assess the effects of intracerebroventricular (i.c.v.) leptin administration on rats fed ad libitum or fasted on 3H GDP binding to brown adipose tissue (BAT). SUBJECTS: Groups of 5-6 ten-week-old male Wistar rats. EXPERIMENTAL DESIGN: An i.c.v. cannula was inserted and unilateral denervation of interscapular brown adipose tissue (BAT) was performed 5 d before each study. Thereafter, leptin was infused i.c.v. during 72 h while rats were fed ad libitum or fasted. Vehicle-infused, pair-fed or fasted rats were used as controls. MEASUREMENTS: 3H GDP binding to innervated and denervated BAT mitochondria. RESULTS: 3H GDP binding to innervated or denervated BAT of rats fed ab libitum compared to vehicle-infused, pair-fed rats was not increased by i.c.v. leptin. 3H GDP binding was lower in fasted than in fed rats, and the difference was larger in innervated than denervated BAT. I.c.v. leptin increased 3H GDP binding by 30% in innervated, and by 51% in denervated BAT (P < 0.05) in fasted rats. CONCLUSIONS: I.c.v. leptin does not increase 3H GDP binding to BAT of rats fed ad libitum compared to pair-fed (food-restricted) rats. In contrast, i.c.v. leptin produces a mild stimulation of 3H GDP binding to BAT of fasted rats. This effect is not mediated by the sympathetic nervous system, because it is observed in both innervated and denervated BAT. These results are compatible with the concept that, in fasting rats, the decrease in leptin secretion contributes to the reduction in 3H GDP binding to BAT mitochondria.

Diet-induced thermogenesis measured over a whole day in obese and nonobese women.

The overall thermogenic response to food intake measured over a whole day in 20 young nondiabetic obese women (body fat mean +/- SEM: 38.6 +/- 0.7%), was compared with that obtained in eight nonobese control women (body fat: 24.7 +/- 0.9%). The energy expenditure of the subjects was continuously measured over 24 h with a respiration chamber, and the spontaneous activity was assessed by a radar system. A new approach was used to obtain the integrated thermogenic response to the three meals ingested over the day (from 8:30 AM to 10:30 PM). This method allows to subtract the energy expended for physical activity from total energy expenditure and to calculate the integrated dietary-induced thermogenesis as the difference between the energy expended without physical activity and basal metabolic rate. The thermogenic response to the three meals (expressed in percentage of the total energy ingested) was found to be blunted in obese women (8.7 +/- 0.8%) as compared with that of controls (14.8 +/- 1.1%). There was an inverse correlation between the percentage body fat and the diet-induced thermogenesis (r = -0.61, p less than 0.001). In addition, the relative increase in diurnal urinary norepinephrine excretion was lower in obese than in the control subjects. It is concluded that a low overall thermogenic response to feeding may be a contributing factor for energy storage in some obese subjects; a blunted response of the sympathetic nervous system could explain this low thermogenic response.

Activity and exploratory behavior after lesions of the medial entorhinal cortex in the woodmouse (Apodemus sylvaticus).

The effects of bilateral electrolytic lesions of the entorhinal cortex were studied in male adult woodmice. Experiments were designed to allow separate analysis of the basal activity level and exploratory behavior. Activity recording was conducted in three situations: (a) 24-hr wheel running in the home cage pre- and postoperatively; (b) 24-hr activity composition in a large enclosure over 4 days, 5 to 9 days postoperatively; and (c) sequence and duration of visits in a residential plus maze 11 to 14 days postoperatively. Medial entorhinal cortex lesion involving the para- and presubiculum increased the 24-hr amount of movements in the enclosure (b) without increasing wheel running in any situation (a or b). This lesion also enhanced the locomotor reactivity to being introduced into the plus maze and impaired exploratory behavior. This last effect was equally apparent when the whole situation was new or when part of the familiar maze was modified. Lesioned woodmice did notice the new element but did not show active focalization of their behavior on that element. Data showed that lesion induced hyperactivity and changes of exploratory behavior were not necessarily associated. Novelty detection was performed but it is not clear now on what information this discrimination was based.