Fast Optimization Scheme for the Muscular Response to FES Stimulation to Design a Smart Electrostimulator

In this article, we present the design of a smart electrostimulator for muscle rehabilitation or reinforcement, using fast computations, in order to control the muscular force. The Ding and al. model allows to predict and to optimize the muscular force response to functional electrical stimulation. [1]. We analyze the estimation of the Ding and al. parameters using an approximation of the force response [6] which depends upon the 6 parameters of the Ding's model and we derive optimization scheme which bypass the time computational expensive integration of the dynamics of the Ding and al. equations

0012: Cardiac effects of a treatment with prolyl-hydroxylase inhibitors (PHI), used to improve exercise performance, in sedentary and trained rats

Stabilization of the Hypoxia Inducible Factor (HIF) using prolyl-hydroxylase inhibitors (PHI) leads to an EPO synthesis which is suspected to be used as a doping practice. Such a treatment is suspected to improve endurance performance by increasing oxygen transport. However the effects of a PHI treatment on heart morphology and function has never been investigated. Therefore the aim of this study was to evaluate whether potential effects of PHI on cardiac function could contribute to explain its beneficial effect on aerobic performance.We tested the effects of a 1 week treatment with a PHI (DMOG, 150mg.kg–1, I.P.) or a placebo (NaCl) on both sedentary (Sed) and trained rats (Ex; trained during 5 weeks before treatment started; 40min at 25m.min–1 per day; 5days/week). Our first result was that PHI increased running performance (+12%, p<0,05) in both Sed and Ex groups. This increased performance was associated with a major increase in total hemoglobin in PHI-treated animals (+13% p<0,05). However, regarding cardiac function and cardiac remodeling no beneficial effect of PHI was observed. Indeed, in hearts of sedentary as well as exercised rats no significal change in any morphological parameters (LVEDs, LVEDd, AWTd, PWTd and RWT) was found. Moreover, no change in systolic function likely to explain enhanced exercise performance was observed in PHI-treated hearts, when evaluated by intraventricular pressure probe (Millar®). Finally it is interesting to note that in sedentary rat hearts an impairment of diastolic function characterized by an altered E/A and dp/dtmin ratios was found when they were challenged with isoproterenol (0,5mg.kg-1). These last results obtained in sedentary hearts could suggest that a more prolonged treatment with such PHI could have deleterious consequences on heart health and point out the danger of such a doping strategy; however, this point remains to be more precisely investigated

Effects of a Lifestyle Program on Vascular Reactivity in Macro- and Microcirculation in Severely Obese Adolescents

Context and Objective: This study aimed to comprehensively assess the macro- and microcirculation of severely obese adolescents (SOA) and normal-weight counterparts and to determine the longitudinal effects of weight loss on vascular function in SOA. Design, Setting, Participants, and Outcome Measures: Seventeen SOA (body mass index z-score = 4.22 ± 0.73) and 19 puberty-matched normal-weight counterparts (body mass index z-score = −0.02 ± 1.04) were included. The SOA participated in a 4 month weight loss program. Brachial artery flow-mediated dilation and response to sublingual nitrate (nitrate-mediated dilation [NMD]) were assessed by high-resolution ultrasound. Microvascular reactivity was evaluated by laser Doppler flowmetry in response to NMD, iontophoresis of acetylcholine and sodium nitroprusside, and local hyperthermia. Plasma insulin, leptin, resistin, C-reactive protein, myeloperoxidase, and tissue plasminogen activator were measured. Results: At baseline, SOA had similar flow-mediated dilation and impaired NMD in the brachial artery compared to normal-weight adolescents. Similarly, peak responses to acetylcholine and sodium nitroprusside iontophoresis and to local hyperthermia were unaltered, whereas cutaneous blood flow after NMD was lower in the forearm microcirculation of SOA. All plasma measurements were significantly higher in SOA. After the 4-month program, SOA presented a weight reduction of 7.4 ± 3.1%, but neither brachial artery nor microvascular reactivity variables were improved. Significant decreases were detected in plasma leptin, myeloperoxidase, and tissue plasminogen activator. Conclusions: Macro- and microvascular endothelial function are preserved in adolescents with severe obesity. Conversely, weight loss does not improve their impaired smooth muscle response to exogenous organic nitrate in both vascular beds, despite reducing plasma markers adversely related to vascular homeostasis.This study was supported by grants from the French Society of Vascular Medicine 2010-2012 (to A.V. and A.P.M), and the Spanish Ministry of Health (CIBERobn CB12/03/30038) (to E.R.

Fast Optimization Scheme for the Muscular Response to FES Stimulation to Design a Smart Electrostimulator

In this article, we present the design of a smart electrostimulator for muscle rehabilitation or reinforcement, using fast computations, in order to control the muscular force. The Ding and al. model allows to predict and to optimize the muscular force response to functional electrical stimulation. [1]. We analyze the estimation of the Ding and al. parameters using an approximation of the force response [6] which depends upon the 6 parameters of the Ding's model and we derive optimization scheme which bypass the time computational expensive integration of the dynamics of the Ding and al. equations

Finite Dimensional Approximation to Muscular Response in Force-Fatigue Dynamics using Functional Electrical Stimulation

International audienceRecent dynamical models, based on the seminal work of V. Hill, allow to predict the muscular response to functional electrostimulation (FES), in the isometric and non-isometric cases. The physical controls are modeled as Dirac pulses and lead to a sampled-data control system, sampling corresponding to times of the stimulation, where the output is the muscular force response. Such a dynamics is suitable to compute optimized controls aiming to produce a constant force or force strengthening, but is complex for real time applications. The objective of this article is to construct a finite dimensional approximation of this response to provide fast optimizing schemes, in particular for the design of a smart electrostimulator for muscularreinforcement or rehabilitation. It is an on-going industrial project based on force-fatigue models, validated by experiments.Moreover it opens the road to application of optimal control to track a reference trajectory in the joint angular variable to produce movement in the non-isometric models

Finite Dimensional Approximation to Muscular Response in Force-Fatigue Dynamics using Functional Electrical Stimulation

Recent dynamical models, based on the seminal work of V. Hill, allow to predict the muscular response to functional electrostimulation (FES), in the isometric and non-isometric cases. The physical controls are modeled as Dirac pulses and lead to a sampled-data control system, sampling corresponding to times of the stimulation, where the output is the muscular force response. Such a dynamics is suitable to compute optimized controls aiming to produce a constant force or force strengthening, but is complex for real time applications. The objective of this article is to construct a finite dimensional approximation of this response to provide fast optimizing schemes, in particular for the design of a smart electrostimulator for muscularreinforcement or rehabilitation. It is an on-going industrial project based on force-fatigue models, validated by experiments.Moreover it opens the road to application of optimal control to track a reference trajectory in the joint angular variable to produce movement in the non-isometric models

Optimal Control Techniques for Sampled-Data Control Systems with Medical Applications

International audienc

0301 : Effects of low and high polyphenols content lettuces consumption on high fat diet induced metabolic syndrome and endothelial dysfunction

Consumption of vegetables has been recommended to reduce the risk of cardiovascular disease. The protection against disease is partly due to bioactive molecules including polyphenols. In order to evaluate the effects of such polyphenols, we supplemented High Fat diet rats with low and high polyphenolic content lettuces. 32 Wistar rats were divided in 4 groups, a control group (Ctrl), a high fat and sucrose diet group (HFS, 60% fat+10%sucrose) and 2 groups that after 6 weeks of HFS diet were supplemented 8 weeks with both HFS diet and either a low or high polyphenol content lettuces (HFS-LP; Blond Oak Leaf, 30g/day vs. HFS-HP; Red Oak Leaf, 30g/day). After 14 weeks of HF diet including 8 weeks of supplementation, we performed a glucose tolerance test and an evaluation of arterial blood pressure (BP) by tail cuff method. Then, aortic endothelial function and eNOS dependent vasodilatation were evaluated ex vivo on isolated rings. Firstly, we observed a higher body weight in HFS group (502±21g) compared to Ctrl group (417±14g) without any effect of both supplementations. Regarding glycemic control, HFS group presented increased fasting blood glucose (1,37g/l vs. 1,20g/l) as well as an impairment of glucose tolerance. Interestingly, both groups with lettuces intake displayed healthy fasting blood glucose values (1.14g/l and 1.15g/l) and an improvement of glucose tolerance. Moreover, both lettuces treatments managed to normalize the increase in mean BP observed in HFS group (HFS; 131mmHg; HFS-LP 120 mmHg; HFS-HP, 117mmHg). However, no effect of lettuce consumption was observed on endothelial dysfunction and impaired eNOS dependent vasodilatation observed in HFS rats. In conclusion, we observed in this study a major effect of lettuce intake on glycemic control as well as arterial BP. However, no effect regarding the difference in polyphenols content has been reported here underlying that the effects were independent of the specific polyphenols contained in the HP lettuce

S-nitrosoproteomics defines a key mechanism of exercise-induced cardioprotection

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Protective Role of Chronic Exercise Training in Modulating the Impact of Hyperglycemia on Vascular Sensitivity to Ischemia-Reperfusion

Hyperglycemia (HG) is associated with increased mortality and morbidity in acute ischemic events. Regardless of the tissue or organs involved, the vascular endothelium is a key target of ischemia-reperfusion (I/R) injury severity. Among endothelium-protective strategies, exercise has been widely described as useful. However, whether this strategy is able to impact the deleterious effect of HG on endothelial function during I/R has never been challenged. For this, 48 male Wistar rats were randomized into 4 groups: sedentary (Sed) or exercised (Ex, 45 min/day, 5 days/week for 5 weeks) rats, treated (hyperglycemic, HG) or not (normoglycemic, NG) with streptozotocin (40 mg/kg, 48 h before procedure). Vascular I/R (120/15 min) was performed by clamping the femoral artery. Arterial and downstream muscular perfusions were assessed using laser speckle contrast imaging. Vascular endothelial function was assessed in vivo 15 min after reperfusion. HG was responsible for impairment of reperfusion blood flow as well as endothelial function. Interestingly exercise was able to prevent those impairments in the HG group. In agreement with the previous results, HG increased reactive oxygen species production and decreased nitric oxide bioavailability whereas exercise training normalized these parameters. It, therefore, appears that exercise may be an effective prevention strategy against the exacerbation of vascular and muscular damage by hyperglycemia during I/R