On Algorithms Based on Joint Estimation of Currents and Contrast in Microwave Tomography

This paper deals with improvements to the contrast source inversion method which is widely used in microwave tomography. First, the method is reviewed and weaknesses of both the criterion form and the optimization strategy are underlined. Then, two new algorithms are proposed. Both of them are based on the same criterion, similar but more robust than the one used in contrast source inversion. The first technique keeps the main characteristics of the contrast source inversion optimization scheme but is based on a better exploitation of the conjugate gradient algorithm. The second technique is based on a preconditioned conjugate gradient algorithm and performs simultaneous updates of sets of unknowns that are normally processed sequentially. Both techniques are shown to be more efficient than original contrast source inversion.Comment: 12 pages, 12 figures, 5 table

Effects of high vs moderate-intensity training on neuroplasticity and functional recovery after focal ischemia

Background and Purpose: This study was designed to compare the effects of high-intensity interval training (HIT) and moderate-intensity continuous training (MOD) on functional recovery and cerebral plasticity during the first 2 weeks following cerebral ischemia. Methods: Rats were randomized as follows: Control (n=15), SHAM (n=9), MCAO (n=13), MCAO-D1 (n=7), MOD (n=13) and HIT (n=13). Incremental tests were performed at day 1 (D1) and 14 (D14) to identify the running speed associated with the lactate threshold (SLT) and the maximal speed (Smax). Functional tests were performed at D1, D7 and D14. Microglia form, cytokines, p75NTR, KCC2 and NKCC1 expression were made at D15. Results-HIT was more effective to improve the endurance performance than MOD and induced a fast recovery of the impaired forelimb grip force. The Iba-1 positive cells with amoeboid form and the pro- and anti-inflammatory cytokine expression were lower in HIT group, mainly in the ipsilesional hemisphere. A p75NTR overexpression is observed on the ipsilesional side together with a restored NKCC1/KCC2 ratio on the contralesional side. Conclusions-Low-volume HIT based on lactate threshold appears to be more effective after cerebral ischemia than work-matched MOD to improve aerobic fitness, grip strength and might promote cerebral plasticity

<p>Cognitive functioning enhancement in older adults: is there an advantage of multicomponent training over Nordic walking?</p>

International audienceIntroduction: We compared Nordic walking training (NW) to a multicomponent training (MCT) program of an equivalent intensity, in older adults. Our main hypothesis was that MCT would result in larger effects on cognitive processes than NW. Methods: Thirty-nine healthy older adults, divided into two groups (NW and MCT), took part in the study (17 males, 22 females, mean age =70.8±0.8 years). They were tested for cardiovascular fitness, motor fitness and cognitive performance during the two weeks preceding and following the 12-week training session (3 times/week), respectively. For both the NW and MCT interventions, the training sessions were supervised by a trainer. Heart rate of participants was monitored during the sessions and then used to make training loads as similar as possible between the two groups (TRaining IMPulse method). Results: Results showed that training resulted in better performance for cardiovascular and motor fitness tests. Among these tests, only two revealed a significant difference between the two groups. The NW group progressed more than the MCT group in the 30 Seconds Chair Stand test, while in the One Leg Stance test, the MCT group progressed more. For the cognitive assessment, a significant effect of training was found for executive functions, spatial memory score, and information processing speed response time, with no differences between the two groups. Conclusion: The study confirmed that physical exercise has a positive impact on cognitive processes with no advantage of MCT intervention over NW training. A possible reason is that NW intervention not only improved cardiovascular capacities, but also motor fitness, including coordination capacities

Mise au point d'une nouvelle méthode pour déterminer l'origine des repas sanguins chez les insectes hématophages. Applications aux Phlébotomes (Diptera : Psychodidae) de Chypre

REIMS-BU Santé (514542104) / SudocSudocFranceF

Effects of High- Versus Moderate-Intensity Trainingon Neuroplasticity and Functional Recovery AfterFocal Ischemia

International audienceI schemic stroke remains the leading cause of long-term physical disorders. Poststroke hemiparesis frequently leads to physical deconditioning that strongly reduces the quality of life and represents an important burden on the family and society. Growing evidence from animal and human experiments indicated that aerobic training induced beneficial effects at the cardiovascular, muscular, cerebral, and functional levels after cerebral ischemia. 1,2 Moderate-intensity aerobic training (MOD; for recommendations see Marsden et al 1) is advised after stroke to improve the locomotor abilities, the peak oxygen uptake (VO 2peak), and the maximal running speed (S max), which are strong indicators of quality of life. Early treadmill training in rodents could also promote functional recovery and cerebral plasticity by upregulating the neurotrophin levels, enhancing synaptogenesis, and limiting microglia-mediated proinflammatory cytokine release in the perilesional zones. 3,4 However, beneficial effects of MOD on functional recovery, aerobic fitness, and quality of life remain frequently insufficient and controversial. 1,5 It is, thus, crucial to reconsider the current guidelines for exercise by defining a safe/effective dosage of training. 5 In this regard, authors recently showed that higher training intensities appeared promising for stroke patients. 6 Indeed, high-intensity interval training (HIT), known to be feasible and safe in moderate stroke patients, 7 could improve VO 2peak , running economy, and functional recovery, but it remains controversial. 6,7 No clear evidence indicated whether the HIT effectiveness is more efficient on aerobic fitness and neuroplasticity than MOD. 6,8 Given that HIT is a time-efficient strategy, we postulated that it might accentuate functional recovery in the acute phase of cerebral ischemia compared with MOD. In light of these considerations, the present study was designed to compare the effects of work-matched HIT and MOD programs on functional outcomes and cerebral plasticity during the first 2 weeks after cerebral ischemia in rats. One of the key points of the endurance protocols relies on determining for each animal the training intensity from an underestimated Background and Purpose-This study was designed to compare the effects of high-intensity interval training (HIT) and moderate-intensity aerobic training (MOD) on functional recovery and cerebral plasticity during the first 2 weeks after cerebral ischemia. Methods-Rats were randomized as follows: control (n=15), SHAM (n=9), middle cerebral artery occlusion (n=13), middle cerebral artery occlusion at day 1 (n=7), MOD (n=13), and HIT (n=13). Incremental tests were performed at day 1 (D1) and 14 (D14) to identify the running speed associated with the lactate threshold (S LT) and the maximal speed (S max). Functional tests were performed at D1, D7, and D14. Microglia form, cytokines, p75 NTR (pan-neurotrophin receptor p75), potassium-chloride cotransporter type 2, and sodium-potassium-chloride cotransporter type 1 expression were made at D15. Results-HIT was more effective to improve the endurance performance than MOD and induced a fast recovery of the impaired forelimb grip force. The ionized calcium binding adaptor molecule 1 (Iba-1)-positive cells with amoeboid form and the pro-and anti-inflammatory cytokine expression were lower in HIT group, mainly in the ipsilesional hemisphere. A p75 NTR overexpression is observed on the ipsilesional side together with a restored sodium-potassium-chloride cotransporter type 1/potassium-chloride cotransporter type 2 ratio on the contralesional side. Conclusions-Low-volume HIT based on lactate threshold seems to be more effective after cerebral ischemia than work-matched MOD to improve aerobic fitness and grip strength and might promote cerebral plasticity. Visual Overview-An online visual overview is available for this article. (Stroke. 2017;48:00-00

Cerebral Ischemia Changed the Effect of Metabosensitive Muscle Afferents on Somatic Reflex Without Affecting Thalamic Activity

International audienceThe purpose of the present study was to examine the contribution of group III and IV metabosensitive afferents at spinal and supraspinal levels in rats subjected to middle cerebral artery occlusion (MCAO) with reperfusion during the acute phase. Animals were randomized in Control (n = 23), SHAM (n = 18), MCAO-D1 (n = 10), and MCAOD-7 (n = 20) groups. Rats performed the Electrical Von Frey and the Adhesive removal tests before the surgery and at day 1 (D1), D3, and D7 after MCAO. Animals were subjected to electrophysiological recordings including the responses of group III/IV metabosensitive afferents to combinations of chemical activators and the triceps brachii somatic reflex activity at D1 or D7. The response of ventral posterolateral (VPL) thalamic nuclei was also recorded after group III/IV afferent activation. Histological measurements were performed to assess the infarct size and to confirm the location of the recording electrodes into the VPL. Behavioral results indicated that MCAO induced disorders of both mechanical sensibility and motor coordination of paretic forepaw during 7 days. Moreover, injured animals exhibited an absence of somatic reflex inhibition from the group III/IV afferents at D1, without affecting the response of both these afferents and the VPL. Finally, the regulation of the central motor drive by group III/IV afferents was modified at spinal level during the acute phase of cerebral ischemia and it might contribute to the observed behavioral disturbances

Physical Exercise as a Diagnostic, Rehabilitation, and Preventive Tool: Influence on Neuroplasticity and Motor Recovery after Stroke

Stroke remains a leading cause of adult motor disabilities in the world and accounts for the greatest number of hospitalizations for neurological disease. Stroke treatments/therapies need to promote neuroplasticity to improve motor function. Physical exercise is considered as a major candidate for ultimately promoting neural plasticity and could be used for different purposes in human and animal experiments. First, acute exercise could be used as a diagnostic tool to understand new neural mechanisms underlying stroke physiopathology. Indeed, better knowledge of stroke mechanisms that affect movements is crucial for enhancing treatment/rehabilitation effectiveness. Secondly, it is well established that physical exercise training is advised as an effective rehabilitation tool. Indeed, it reduces inflammatory processes and apoptotic marker expression, promotes brain angiogenesis and expression of some growth factors, and improves the activation of affected muscles during exercise. Nevertheless, exercise training might also aggravate sensorimotor deficits and brain injury depending on the chosen exercise parameters. For the last few years, physical training has been combined with pharmacological treatments to accentuate and/or accelerate beneficial neural and motor effects. Finally, physical exercise might also be considered as a major nonpharmacological preventive strategy that provides neuroprotective effects reducing adverse effects of brain ischemia. Therefore, prestroke regular physical activity may also decrease the motor outcome severity of stroke

Physical Exercise as a Diagnostic, Rehabilitation, and Preventive Tool: Influence on Neuroplasticity and Motor Recovery after Stroke

International audienceStroke remains a leading cause of adult motor disabilities in the world and accounts for the greatest number of hospitalizations for neurological disease. Stroke treatments/therapies need to promote neuroplasticity to improve motor function. Physical exercise is considered as a major candidate for ultimately promoting neural plasticity and could be used for different purposes in human and animal experiments. First, acute exercise could be used as a diagnostic tool to understand new neural mechanisms underlying stroke physiopathology. Indeed, better knowledge of stroke mechanisms that affect movements is crucial for enhancing treatment/rehabilitation effectiveness. Secondly, it is well established that physical exercise training is advised as an effective rehabilitation tool. Indeed, it reduces inflammatory processes and apoptotic marker expression, promotes brain angiogenesis and expression of some growth factors, and improves the activation of affected muscles during exercise. Nevertheless, exercise training might also aggravate sensorimotor deficits and brain injury depending on the chosen exercise parameters. For the last few years, physical training has been combined with pharmacological treatments to accentuate and/or accelerate beneficial neural and motor effects. Finally, physical exercise might also be considered as a major nonpharmacological preventive strategy that provides neuroprotective effects reducing adverse effects of brain ischemia. Therefore, prestroke regular physical activity may also decrease the motor outcome severity of stroke

Modulation of the spinal excitability by muscle metabosensitive afferent fibers

International audienceno abstrac

Effect of tenotomy on metabosensitive afferent fibers from tibialis anterior muscle.

In previous studies, the effect of tenotomy had been focused mainly on muscle properties (typology, capillarity, force, etc.). Little attention was paid to the metabosensitive fibers from groups III and IV (also called 'ergoreceptors' or 'exercise receptors'). In the current study, we assessed the metabosensitive responses in a rat model with tenotomized muscle. Two groups of animals were included: a control group (C, no tenotomy) and a tenotomized group (Tn, transection of the distal tendon of the left tibialis anterior). After 10 weeks, we observed in the Tn group a significant decrease in the metabosensitive afferent responses to electrically induced fatigue and to chemical agents (KCl and lactic acid), known to activate the metabosensitive fibers. These data indicate that (1) tenotomy induces an alteration in the metabosensitive response and consequently modifies the sensory-motor loop; (2) metabosensitive fibers may have a secondary role in tenotomy-induced muscle properties alterations. Additional studies are required to improve our understanding of the metabosensitive responses after tendon or nerve injury