Potentiation and electrical stimulus frequency during self-paced exercise and recovery

The aim of this study was to investigate the effect of potentiation on stimulation-induced muscle function during and after an intense bout of self-paced dynamic exercise. Ten active subjects performed a time trial involving repetitive concentric extension-flexion of the right knee using a Biodex dynamometer. Electrical stimulation before and after a 5 s maximal isometric voluntary contraction was performed before the start of the time trial and immediately (< 5 s) after each 20% of the time trial as well as 1, 2, 4 and 8 min after time trial termination. Potentiation was observed before the time trial and as early as 1–2 min after the time trial, but no potentiation was detected during or immediately after the time trial for neither single or paired stimuli. At termination of the time trial, “potentiated” peak torque was significantly more reduced than “unpotentiated” peak torque for single stimulus (−65 ± 10% and −42 ± 18%, respectively) and paired stimuli at 100 Hz (−51 ± 10% and −33 ± 15%, respectively). Faster recovery for “potentiated” compared to “unpotentiated” peak torque indicate that potentiate peak torque measurements or delay the post-exercise measurements more than a few seconds, will underestimate peripheral fatigue. In conclusion, the potentiation after maximal contraction disappears during intense exercise. Whether the muscle is already potentiated during intense contraction or fatiguing mechanisms inhibits potentiation remains to be clarified.

Improving testicular blood flow with electroacupuncture-like percutaneous nerve stimulation in an experimental rat model of testicular torsion

INTRODUCTION

The purpose of this study was to determine the blood-flow-enhancing effect of electroacupuncture (EA) in an experimental rat model of testicular torsion.

METHODS

At the first stage, 3D color Doppler ultrasound (3D-CDUS) scans were made to detect baseline perfusion of each testicle in 12 male albino Wistar rats. Then, the left testicles of all rats were twisted 180° clockwise, and 3D-CDUS recordings were repeated. In the next step, 10-Hz EA was applied for 5 min over the T13 and L4 dermatome territories in the study group of six rats. In the control group of six rats, acupuncture needles were inserted in the same manner, but EA was not applied. Baseline, posttorsion, and postintervention (EA and manual needling) 3D-CDUS perfusion recordings were interpreted as volumetric data, and group comparisons were performed.

RESULTS

After EA, we observed statistically significant perfusion improvements in both the ipsilateral torsed and contralateral nontorsed testicles. In the control group, testicular perfusion did not show a significant change after manual needling.

CONCLUSION

EA can improve testicular blood flow bilaterally in a rat model of unilateral testicular torsion at 180°.

Electrical stimulation for cortical mapping reduces the density of high frequency oscillations

BACKGROUND

High frequency oscillations (HFOs, 80-500 Hz) are EEG biomarkers for epileptogenic areas. HFOs are also indicators of disease activity as HFO rates increase after reduction of antiepileptic medication. Electrical stimulation (ES) can be used for diagnostic purposes as well as therapy in patients with refractory epilepsy. This study investigates the occurrence and changes of HFOs during ES in patients with refractory epilepsy.

OBJECTIVE

Analysis of the effects of ES using intracranial ES on the occurrence of epileptic HFOs.

METHODS

Patients underwent ES for diagnostic purposes. Ripples (80-200 Hz) and fast ripples (200-500 Hz) were visually marked in a baseline EEG segment prior to ES, after each period of ES as well as after the end of ES. In patients in whom ES triggered a seizure a pre- and postictal segment was marked. Rates of HFOs were compared for the different time periods using a Spearman's correlation and Wilcoxon rank sum test (p<0.05).

RESULTS

12 patients with 911 EEG channels were analyzed. Ripple (r=-0.42, p<0.001) as well as fast ripple (r=-0.21, p<0.001) rates decreased significantly over the course of stimulation. This phenomenon was not focal over the seizure onset or neighboring contacts but even observed over distant contacts.

CONCLUSIONS

ES resulted in a gradual decrease of HFO-Rates over time. The decrease of HFOs was not limited to SOZ areas. If HFOs are considered as markers of disease activity the reduction in HFO-rates as a result of intracranial ES has to be interpreted as a reduction of disease activity.

Effects of acetylcholine and electrical stimulation on glial cell line-derived neurotrophic factor production in skeletal muscle cells

Glial cell line-derived neurotrophic factor (GDNF) is a neurotrophic factor required for survival of neurons in the central and peripheral nervous system. Specifically, GDNF has been characterized as a survival factor for spinal motor neurons. GDNF is synthesized and secreted by neuronal target tissues, including skeletal muscle in the peripheral nervous system; however, the mechanisms by which GDNF is synthesized and released by skeletal muscle are not fully understood. Previous results suggested that cholinergic neurons regulate secretion of GDNF by skeletal muscle. In the current study, GDNF production by skeletal muscle myotubes following treatment with acetylcholine was examined. Acetylcholine receptors on myotubes were identified with labeled alpha-bungarotoxin and were blocked using unlabeled alpha-bungarotoxin. The question of whether electrical stimulation has a similar effect to that of acetylcholine was also investigated. Cells were stimulated with voltage pulses; at 1 and 5 Hz frequencies for times ranging from 30 min to 48 h. GDNF content in myotubes and GDNF in conditioned culture medium were quantified by enzyme-linked immunosorbant assay. Results suggest that acetylcholine and short-term electrical stimulation reduce GDNF secretion, while treatment with carbachol or long-term electrical stimulation enhances GDNF production by skeletal muscle.

Carotid baroreceptor stimulation: a potential solution for resistant hypertension

Resistant hypertension indicates that the blood pressure cannot reach the target value despite standard drug treatment, which harbors an increased risk for cardiovascular diseases. The role of the carotid sinus in regulating blood pressure has long been observed; thereby, the idea that treating resistant hypertension by stimulating carotid baroreceptors emerged. Nevertheless, this idea has been abandoned for years due to technical limitations. Recently, with the evolutions in implantable electrical devices, expectations for treating resistant hypertension with baroreceptor stimulation have increased. Positive results from several multicenter clinical trials further captured the researchers’ enthusiasm for more effective baroreceptor-stimulating devices. This study reviews the recent progress in baroreceptor stimulation as a treatment alternative for resistant hypertension.

Electrical stimulation using sine waveform prevents unloading-induced muscle atrophy in the deep calf muscles of rat

The aim of this study was to compare the effects of electrical stimulation by using rectangular and sine waveforms in the prevention of deep muscle atrophy in rat calf muscles. Rats were randomly divided into the following groups: control, hindlimb unloading (HU), and HU plus electrical stimulation (ES). The animals in the ES group were electrically stimulated using rectangular waveform (RS) on the left calves and sine waveform (SS) on the right calves, twice a day, for 2 weeks during unloading. HU for 2 weeks resulted in a loss of the muscle mass, a decrease in the cross-sectional area of the muscle fibers, and overexpression of ubiquitinated proteins in the gastrocnemius and soleus muscles. In contrast, electrical stimulation with RS attenuated the HU-induced reduction in the cross-sectional area of muscle fibers and the increase of ubiquitinated proteins in the gastrocnemius muscle. However, electrical stimulation with RS failed to prevent muscle atrophy in the deep portion of the gastrocnemius and the soleus muscles. Nevertheless, electrical stimulation with SS attenuated the HU-induced muscle atrophy and the up-regulation of ubiquitinated proteins in both gastrocnemius and soleus muscles. This indicates that SS was more effective in the prevention of deep muscle atrophy than RS. Since the skin muscle layers act like the plates of a capacitor, separated by the subcutaneous adipose layer, the SS can pass through this capacitor more easily than the RS. Hence, SS can prevent the progressive loss of muscle fibers in the deep portion of the calf muscles.

Electrical stimulation of a small brain area reversibly disrupts consciousness

The neural mechanisms that underlie consciousness are not fully understood. We describe a region in the human brain where electrical stimulation reproducibly disrupted consciousness. A 54-year-old woman with intractable epilepsy underwent depth electrode implantation and electrical stimulation mapping. The electrode whose stimulation disrupted consciousness was between the left claustrum and anterior-dorsal insula. Stimulation of electrodes within 5mm did not affect consciousness. We studied the interdependencies among depth recording signals as a function of time by nonlinear regression analysis (h(2) coefficient) during stimulations that altered consciousness and stimulations of the same electrode at lower current intensities that were asymptomatic. Stimulation of the claustral electrode reproducibly resulted in a complete arrest of volitional behavior, unresponsiveness, and amnesia without negative motor symptoms or mere aphasia. The disruption of consciousness did not outlast the stimulation and occurred without any epileptiform discharges. We found a significant increase in correlation for interactions affecting medial parietal and posterior frontal channels during stimulations that disrupted consciousness compared with those that did not. Our findings suggest that the left claustrum/anterior insula is an important part of a network that subserves consciousness and that disruption of consciousness is related to increased EEG signal synchrony within frontal-parietal networks.

Empirical evaluation of gastrocnemius and soleus function during walking

Distinguishing gastrocnemius and soleus muscle function is relevant for treating gait disorders in which abnormal plantarflexor activity may contribute to pathological movement patterns. Our objective was to use experimental and computational analysis to determine the influence of gastrocnemius and soleus activity on lower limb movement, and determine if anatomical variability of the gastrocnemius affected its function. Our hypothesis was that these muscles exhibit distinct functions, with the gastrocnemius inducing limb flexion and the soleus inducing limb extension. To test this hypothesis, the gastrocnemius or soleus of 20 healthy participants was electrically stimulated for brief periods (90 ms) during mid- or terminal stance of a random gait cycle. Muscle function was characterized by the induced change in sagittal pelvis, hip, knee, and ankle angles occurring during the 200 ms after stimulation onset. Results were corroborated with computational forward dynamic gait models, by perturbing gastrocnemius or soleus activity during similar portions of the gait cycle. Mid- and terminal stance gastrocnemius stimulation induced posterior pelvic tilt, hip flexion and knee flexion. Mid-stance gastrocnemius stimulation also induced ankle dorsiflexion. In contrast mid-stance soleus stimulation induced anterior pelvic tilt, knee extension and plantarflexion, while late-stance soleus stimulation induced relatively little change in motion. Model predictions of induced hip, knee, and ankle motion were generally in the same direction as those of the experiments, though the gastrocnemius's results were shown to be quite sensitive to its knee-to-ankle moment arm ratio.

Temporally unstructured electrical stimulation to the amygdala suppresses behavioral chronic seizures of the pilocarpine animal model

Electrical stimulation applied to the basolateral amygdala in the pentylenetetrazole animal model of seizures may result in either a proconvulsant or an anticonvulsant effect depending on the interpulse intervals used: periodic or nonperiodic, respectively. We tested the effect of this electrical stimulation temporal coding on the spontaneous and recurrent behavioral seizures produced in the chronic phase of the pilocarpine animal model of temporal lobe epilepsy, an experimental protocol that better mimics the human condition. After 45 days of the pilocarpine-induced status epilepticus, male Wistar rats were submitted to a surgical procedure for the implantation of a bipolar electrical stimulation electrode in the right basolateral amygdala and were allowed to recover for seven days. The animals were then placed in a glass box, and their behaviors were recorded daily on DVD for 6h for 4 consecutive days (control period). Spontaneous recurrent behavioral seizures when showed in animals were further recorded for an extra 4-day period (treatment period), under periodic or nonperiodic electrical stimulation. The number, duration, and severity of seizures (according to the modified Racine's scale) during treatment were compared with those during the control period. The nonperiodically stimulated group displayed a significantly reduced total number and duration of seizures. There was no difference between control and treatment periods for the periodically stimulated group. Results corroborate previous findings from our group showing that nonperiodic electrical stimulation has a robust anticonvulsant property. In addition, results from the pilocarpine animal model further strengthen nonperiodic electrical stimulation as a valid therapeutic approach in current medical practice. Our working hypothesis is that temporally unstructured electrical stimulation may wield its effect by desynchronizing neural networks involved in the ictogenic process.

Feasibility of neuromuscular electrical stimulation in critically ill patients

OBJECTIVE

Critically ill patients often develop intensive care unit-acquired weakness. Reduction in muscle mass and muscle strength occurs early after admission to the intensive care unit (ICU). Although early active muscle training could attenuate this intensive care unit-acquired weakness, in the early phase of critical illness, a large proportion of patients are unable to participate in any active mobilization. Neuromuscular electrical stimulation (NMES) could be an alternative strategy for muscle training. The aim of this study was to investigate the safety and feasibility of NMES in critically ill patients.

DESIGN

This is an observational study.

SETTING

The setting is in the medical and surgical ICUs of a tertiary referral university hospital.

PATIENTS

Fifty patients with a prognosticated prolonged stay of at least 6 days were included on day 3 to 5 of their ICU stay. Patients with preexisting neuromuscular disorders and patients with musculoskeletal conditions limiting quadriceps contraction were excluded.

INTERVENTION

Twenty-five minutes of simultaneous bilateral NMES of the quadriceps femoris muscle. This intervention was performed 5 days per week (Monday-Friday). Effective muscle stimulation was defined as a palpable and visible contraction (partial or full muscle bulk).

MEASUREMENTS

The following parameters, potentially affecting contraction upon NMES, were assessed: functional status before admission to the ICU (Barthel index), type and severity of illness (Acute Physiology And Chronic Health Evaluation II score and sepsis), treatments possibly influencing the muscle contraction (corticosteroids, vasopressors, inotropes, aminoglycosides, and neuromuscular blocking agents), level of consciousness (Glasgow Coma Scale, score on 5 standardized questions evaluating awakening, and sedation agitation scale), characteristics of stimulation (intensity of the NMES, number of sessions per patient, and edema), and neuromuscular electrophysiologic characteristics. Changes in heart rate, blood pressure, oxygen saturation, respiratory rate, and skin reactions were registered to assess the safety of the technique.

RESULTS

In 50% of the patients, an adequate quadriceps contraction was obtained in at least 75% of the NMES sessions. Univariate analysis showed that lower limb edema (P<.001), sepsis (P=.008), admission to the medical ICU (P=.041), and treatment with vasopressors (P=.011) were associated with impaired quadriceps contraction. A backward multivariate analysis identified presence of sepsis, lower limb edema, and use of vasopressors as independent predictors of impaired quadriceps contraction (R2=59.5%). Patients responded better to NMES in the beginning of their ICU stay in comparison with after 1 week of ICU stay. There was no change in any of the safety end points with NMES.

CONCLUSIONS

Critically ill patients having sepsis, edema, or receiving vasopressors were less likely to respond to NMES with an adequate quadriceps contraction. Neuromuscular electrical stimulation is a safe intervention to be administered in the ICU.

Transcranial Direct Current Stimulation Combined with Treadmill Gait Training in Delayed Neuro-psychomotor Development

[Purpose] The aim of the present study was to describe the results of transcranial direct current stimulation combined with treadmill training in a child with delayed neuro-psychomotor development. [Subject and Methods] Transcranial direct current stimulation (intensity: 1 mA) was applied over the primary motor cortex for 20 minutes during simultaneous treadmill training (2.5 km/h) in ten sessions. [Results] Clinically significant improvement was found in motor development (fine motor subscale, 23 to 25; gross motor subscale, 32 to 41). Reductions in mean oscillation of the center of pressure were found in the anteroposterior (239.2 to 146.5 mm) and mediolateral (177.4 to 149.2 mm) directions. Increases occurred in cadence (106 to 123 steps/minute), step length (0.16 to 0.23 m), step width (0.09 to 0.14 m) and gait velocity with support (0.3 to 0.7 m/s). [Conclusion] After treatment, the child was able to initiate the standing position for the first time and walk without support.

Functional electrical stimulation to ankle dorsiflexor and plantarflexor using single foot switch in patients with hemiplegia from hemorrhagic stroke

Objective

To evaluate the effects of functional electrical stimulation (FES) to ankle dorsiflexor (DF) and ankle plantarflexor (PF) on kinematic and kinetic parameters of hemiplegic gait.

Methods

Fourteen post-stroke hemiplegic patients were considered in this study. Electrical stimulation was delivered to ankle DF during the swing phase and ankle PF during the stance phase via single foot switch. Kinematic and kinetic data were collected using a computerized motion analysis system with force plate. Data of no stimulation (NS), DF stimulation only (DS), DF and PF stimulation (DPS) group were compared among each other.

Results

Peak ankle dorsiflexion angle during swing phase is significantly greater in DS group (-1.55°±9.10°) and DPS group (-2.23°±9.64°), compared with NS group (-6.71°±11.73°) (p<0.05), although there was no statistically significant difference between DS and DPS groups. Ankle plantarflexion angle at toe-off did not show significant differences among NS, DS, and DPS groups. Peak knee flexion in DPS group (34.12°±13.77°) during swing phase was significantly greater than that of NS group (30.78°±13.64°), or DS group (32.83°±13.07°) (p<0.05).

Conclusion

In addition to the usual FES application stimulating ankle DF during the swing phase, stimulation of ankle PF during stance phase can help to increase peak knee flexion during the swing phase. This study shows the advantages of stimulating the ankle DF and PF using single foot switch for post-stroke gait.

Effect of the time of day on central and peripheral fatigue during 2-min maximal voluntary contractions in persons with multiple sclerosis: gender differences

There is a lack of data on fatigue changes within 24h among patients with multiple sclerosis. The purpose of this study was to evaluate the effect of time of day on central and peripheral fatigue during a continuous 2-min maximal voluntary contraction of the quadriceps muscle in women and men with multiple sclerosis (MS). We studied age-matched MS patients (range, 40-50years). The inclusion criteria for patients were: a Kurtzke Expanded Disability Status score and a Fatigue Severity Scale score. We found a significant gender difference in central activation ratio (CAR) in the evening. At the end of the 2-min maximal voluntary contraction (MVC), the voluntary torque decreased by about 65% in men and women with MS in both the morning and evening. We also observed that, in women, CAR decreased markedly during the first 30s in the evening test. The most interesting finding of our study is that central fatigue increased, whereas peripheral fatigue decreased markedly in the evening only in women. It remains unclear why women's central fatigue is greater in the evening than in the morning.

Non-intrusive real-time breathing pattern detection and classification for automatic abdominal functional electrical stimulation

Abdominal Functional Electrical Stimulation (AFES) has been shown to improve the respiratory function of people with tetraplegia. The effectiveness of AFES can be enhanced by using different stimulation parameters for quiet breathing and coughing. The signal from a spirometer, coupled with a facemask, has previously been used to differentiate between these breath types. In this study, the suitability of less intrusive sensors was investigated with able-bodied volunteers. Signals from two respiratory effort belts, positioned around the chest and the abdomen, were used with a Support Vector Machine (SVM) algorithm, trained on a participant by participant basis, to classify, in real-time, respiratory activity as either quiet breathing or coughing. This was compared with the classification accuracy achieved using a spirometer signal and an SVM. The signal from the belt positioned around the chest provided an acceptable classification performance compared to the signal from a spirometer (mean cough (c) and quiet breath (q) sensitivity (Se) of Se(c)=92.9% and Se(q)=96.1% vs. Se(c)=90.7% and Se(q)=98.9%). The abdominal belt and a combination of both belt signals resulted in lower classification accuracy. We suggest that this novel SVM classification algorithm, combined with a respiratory effort belt, could be incorporated into an automatic AFES device, designed to improve the respiratory function of the tetraplegic population.

Influence of electrical stimulation on calpain and ubiquitin-proteasome systems in the denervated and unloaded rat tibialis anterior muscles

The influence of electrical stimulation on calpain and ubiquitin-proteasome systems was examined in the denervated and unloaded tibialis anterior muscles of male Wistar rats. Animals were divided into 5 groups: control, denervation, denervation plus electrical stimulation, unloading, and hindlimb unloading plus electrical stimulation groups. Due to denervation and unloading for 14 days, muscle atrophy markedly occurred in the denervated and unloading animals, and the atrophy in the former was significantly more severe than that in the latter. In the denervated muscle, the atrophy was significantly attenuated by the electrical stimulation, but not in the unloaded muscle. Overexpression of calpain-2 and ubiquitinated proteins was observed only in denervated muscles. In the unloaded animals, though the expression level of calpain-2 appeared to be slightly higher than that in the control, the expression level of ubiquitinated proteins was almost the same as that in the control. The overexpression of calpain-1, calpain-2, and ubiquitinated proteins in the denervated muscle was inhibited by the electrical stimulation. However, there was no difference in these expressions between the unloaded and unloaded plus electrical stimulation groups. The mechanism of the preventive effect of the electrical stimulation on muscle atrophy might differ between the denervated and unloaded muscles.

Simultaneous recording of mouse retinal ganglion cells during epiretinal or subretinal stimulation

We compared response patterns and electrical receptive fields (ERF) of retinal ganglion cells (RGCs) during epiretinal and subretinal electrical stimulation of isolated mouse retina. Retinas were stimulated with an array of 3200 independently controllable electrodes. Four response patterns were observed: a burst of activity immediately after stimulation (Type I cells, Vision Research (2008), 48, 1562-1568), delayed bursts beginning >25ms after stimulation (Type II), a combination of both (Type III), and inhibition of ongoing spike activity. Type I responses were produced more often by epiretinal than subretinal stimulation whereas delayed and inhibitory responses were evoked more frequently by subretinal stimulation. Response latencies were significantly shorter with epiretinal than subretinal stimulation. These data suggest that subretinal stimulation is more effective at activating intraretinal circuits than epiretinal stimulation. There was no significant difference in charge threshold between subretinal and epiretinal configurations. ERFs were defined by the stimulating array surface area that successfully stimulated spikes in an RGC. ERFs were complex in shape, similar to receptive fields mapped with light. ERF areas were significantly smaller with subretinal than epiretinal stimulation. This may reflect the greater distance between stimulating electrodes and RGCs in the subretinal configuration. ERFs for immediate and delayed responses mapped within the same Type III cells differed in shape and size, consistent with different sites and mechanisms for generating these two response types.

Functional improvement and maturation of rat and human engineered heart tissue by chronic electrical stimulation

Spontaneously beating engineered heart tissue (EHT) represents an advanced in vitro model for drug testing and disease modeling, but cardiomyocytes in EHTs are less mature and generate lower forces than in the adult heart. We devised a novel pacing system integrated in a setup for videooptical recording of EHT contractile function over time and investigated whether sustained electrical field stimulation improved EHT properties. EHTs were generated from neonatal rat heart cells (rEHT, n=96) or human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hEHT, n=19). Pacing with biphasic pulses was initiated on day 4 of culture. REHT continuously paced for 16-18 days at 0.5Hz developed 2.2× higher forces than nonstimulated rEHT. This was reflected by higher cardiomyocyte density in the center of EHTs, increased connexin-43 abundance as investigated by two-photon microscopy and remarkably improved sarcomere ultrastructure including regular M-bands. Further signs of tissue maturation include a rightward shift (to more physiological values) of the Ca(2+)-response curve, increased force response to isoprenaline and decreased spontaneous beating activity. Human EHTs stimulated at 2Hz in the first week and 1.5Hz thereafter developed 1.5× higher forces than nonstimulated hEHT on day 14, an ameliorated muscular network of longitudinally oriented cardiomyocytes and a higher cytoplasm-to-nucleus ratio. Taken together, continuous pacing improved structural and functional properties of rEHTs and hEHTs to an unprecedented level. Electrical stimulation appears to be an important step toward the generation of fully mature EHT.

Effects of high voltage electrical stimulation on the rate of pH decline, meat quality and color stability in chilled beef carcasses

OBJECTIVE

To determine the effects of high voltage electrical stimulation (HVES, 800 Voltage) on rapid decreases in pH values and improvements in meat quality.

METHODS

A total of 50 beef carcasses were applied, divided into two groups, one as a control and another for HVES. Meat quality was evaluated based on M. longissimus dorsi by examining pH and temperature levels at 1, 2, 5, 10 and 24 h, while color stability was examined seven days after slaughter.

RESULTS

HVES decreased the pH values of the meat and accelerated rigor mortis (P<0.05). HVES caused differences in instrumental color values compared with the control groups across the ageing period at 4 °C.

CONCLUSION

the HVES had positive effects on meat quality and color stability, in contrast to undesirable consumer preferences.

Could Low-Frequency Electromyostimulation Training be an Effective Alternative to Endurance Training? An Overview in One Adult

This preliminary study aimed to investigate the effects of a six-week low-frequency electromyostimulation training (10Hz) on the cardiovascular, respiratory and muscular systems. To that purpose, aerobic capacity, knee extensor muscles strength and architecture, muscle sympathetic nervous activity, blood pressure and heart rate have been evaluated in one healthy male subject (33 year-old, 1.73 m, 73 kg). Results showed improvement of aerobic capacity (+4.5% and +11.5% for maximal oxygen uptake and ventilatory threshold) and muscle strength (+11% and +16% for voluntary and evoked force). Moreover, for the first time, this study demonstrated low-frequency training effects on muscle architecture (+3%, +12% and -11% for muscle thickness, pennation angle and fascicle length) and cardiovascular parameters (-22%, -18% and -21% for resting muscle sympathetic nervous activity, heart rate and mean blood pressure). Interestingly, these results suggest that this method may have beneficial effects on all systems of the body. The investigation of training effects on muscle architecture and cardiovascular parameters should therefore be pursued since highly deconditioned subjects are likely to fully benefit from these adaptations. Key pointsThese results confirmed that 5 weeks of low-frequency electrical stimulation have beneficial effects on aerobic capacity and muscle strength.This study demonstrated that low-frequency electrical stimulation applied for as short as 5 weeks have a great impact on muscle architecture and cardiovascular parameters and control.This type of training might therefore be interesting for rehabilitation of patients who are unable to perform endurance exercises.

Functional electrical stimulation cycling in youth with spinal cord injury: A review of intervention studies

CONTEXT

Preliminary research suggests that functional electrical stimulation cycling (FESC) might be a promising intervention for youth with spinal cord injury (SCI).

OBJECTIVE

To review the evidence on FESC intervention in youth with SCI.

METHODS

Systematic literature searches were conducted during December 2012. Two reviewers independently selected titles, abstracts, and full-text articles. Of 40 titles retrieved, six intervention studies met inclusion criteria and were assessed using American Academy for Cerebral Palsy and Developmental Medicine Levels of Evidence and Conduct Questions for Group Design.

RESULTS

The study results were tabulated based on levels of evidence, with outcomes categorized according to the International Classification of Functioning, Disability, and Health framework. Evidence from the six included studies suggests that FESC is safe for youth with SCI, with no increase in knee/hip injury or hip displacement. Results from one level II randomized controlled trial suggest that a thrice weekly, 6-month FESC program can positively influence VO2 levels when compared with passive cycling, as well as quadriceps strength when compared with electrical stimulation and passive cycling.

CONCLUSIONS

FESC demonstrates limited yet encouraging results as a safe modality to mitigate effects of inactivity in youth with SCI. More rigorous research involving a greater number of participants is needed before clinicians can be confident of its effectiveness.

Closed chain assessment of quadriceps activation using the superimposed burst technique

The superimposed burst technique is used to estimate quadriceps central activation ratio during a maximal voluntary isometric contraction, which is calculated from force data during an open-chain knee extension task. Assessing quadriceps activation in a closed-chain position would more closely simulate the action of the quadriceps during activity. Our aim was to determine the test-retest reliability of the quadriceps central activation ratio in the closed chain.

METHODS

Twenty-two healthy, active volunteers (13M/12F; age=23.8±3; height=72.7±14.5cm; mass=175.3±9.6kg) were recruited to participate. Knee extension MVIC torque and the peak torque during a superimposed electrical stimulus delivered to the quadriceps during an MVIC were measured to estimate quadriceps CAR. Interclass correlation coefficients were used to assess test-retest reliability between sessions, and Bland-Altman plots to graphically assess agreement between sessions.

RESULTS

Test-retest reliability was fair for CAR (ICC2,k=0.68; P=0.005), with a mean difference of -2.8±10.3%, and limits of agreement ranging -23.1-18.1%.

CONCLUSIONS

CAR calculated using the superimposed burst technique is moderately reliable in a closed-chain position using technique-based instruction. Although acceptable reliability was demonstrated, wide limits of agreement suggest high variability between sessions.

An Arbitrary Waveform Wearable Neuro-stimulator System for Neurophysiology Research on Freely Behaving Animals

Portable wireless neuro-stimulators have been developed to facilitate long-term cognitive and behavioral studies on the central nervous system in freely moving animals. These stimulators can provide precisely controllable input(s) to the nervous system, without distracting the animal attention with cables connected to its body. In this study, a low power backpack neuro-stimulator was developed for animal brain researches that can provides arbitrary stimulus waveforms for the stimulation, while it is small and light weight to be used for small animals including rats. The system consists of a controller that uses an RF link to program and activate a small and light microprocessor-based stimulator. A Howland current source was implemented to produce precise current controlled arbitrary waveform stimulations. The system was optimized for ultra-low power consumption and small size. The stimulator was first tested for its electrical specifications. Then its performance was evaluated in a rat experiment when electrical stimulation of medial longitudinal fasciculus induced circling behavior. The stimulator is capable of delivering programmed stimulations up to ± 2 mA with adjusting steps of 1 μA, accuracy of 0.7% and compliance of 6 V. The stimulator is 15 mm × 20 mm × 40 mm in size, weights 13.5 g without battery and consumes a total power of only 5.l mW. In the experiment, the rat could easily carry the stimulator and demonstrated the circling behavior for 0.1 ms current pulses of above 400 μA. The developed system has a competitive size and weight, whereas providing a wide range of operation and the flexibility of generating arbitrary stimulation patterns ideal for long-term experiments in the field of cognitive and neuroscience research.

Electrophysiological evidence on epileptiform activity enhanced by electrical stimulation of teeth in rats

The aim of this study was to evaluate the possible effects of electrical stimulation (ES) of tooth on penicillin-induced epileptiform activity in rats. Experiment was realized on 24 adult male Sprague Dawley rats. Rats were assigned three groups [stimulation group (SG), penicillin group (PG), and penicillin+stimulation group (PSG)]. In SG, ES was only applied. Ten pulses of electrical current were delivered to the teeth for a duration of 2 milliseconds at 1-second intervals from a stimulator. Currents were applied in the range of 40-240 μA with 40 μA steps. Electrocorticography (ECoG) recordings were taken before and after ES. In PG, ECoG recordings were taken before and during the injection of penicillin. In PSG, after epileptiform activity was induced, ES was applied and ECoG recordings were taken as in SG. All the data were analyzed with Student's t test. Applied currents did not cause any epileptiform activity in SG. When the PSG was compared with the PG it was seen that the spike frequency of epileptiform activity increased in a statistically significant way after application of 240 μA (P < 0·05). On the other hand current application caused an increase in the spike amplitude of the PSG compared with the amplitude of the PG, but it was not statistically significant. We concluded that ES of tooth with high current can trigger epileptiform activity in rats. For this reason, further research is required to evaluate the effects of ES of tooth for pulp testing on epileptic human subjects and antiepileptic drug users.

Current-modulated electrical stimulation as a treatment for peripheral nerve regeneration in diabetic rats

PURPOSE

To study if electrical stimulation (ES) can be a useful tool to improve functional recovery after neuronal injury in the peripheral nervous system.

METHODS

We studied the effects of 2 Hz of percutaneous ES at different intensities of 1, 10 and 20 mA on peripheral nerve regeneration in rats with diabetes induced by streptozotocin. Non-stimulated diabetic rats were used as the sham-controls. A10-mm gap was made in the rat sciatic nerve by suturing the stumps into silicone rubber tubes and stimulation was carried out every other day for 3 weeks starting 1 week after surgery.

RESULTS

After 4 weeks of recovery, the diabetic rats showed that ES of 1 mA or above could increase the cutaneous blood flow in their ipsilateral hindpaw to the injury. ES of 10 mA could improve the amplitude and the area of evoked muscle action potentials with faster target muscle reinnervation. ES of 10 mA could also ameliorate the calcitonin gene-related peptide expression in lamina I-II regions in the dorsal horn ipsilateral to the injury and the number of macrophages in the diabetic distal sciatic nerve. The impaired growth and maturation of regenerating axons in diabetic rat could be improved by ES of 10 mA or above.

CONCLUSIONS

All these results lead to the conclusion that ES of 10 mA or above might be necessary to improve regeneration after a dissect lesion of the sciatic nerve in the diabetic rat.

Cyclical electrical stimulation increases strength and improves activity after stroke: a systematic review

QUESTION

Does electrical stimulation increase strength after stroke and are any benefits maintained beyond the intervention period or carried over to activity?

DESIGN

Systematic review with meta-analysis of randomised or controlled trials.

PARTICIPANTS

Adults who have had a stroke.

INTERVENTION

Cyclical electrical stimulation applied in order to increase muscle strength.

OUTCOME MEASURES

Strength measures had to be representative of maximum voluntary contraction and were obtained as continuous measures of force or torque, or ordinal measures such as manual muscle tests. Activity was measured using direct measures of performance that produced continuous or ordinal data, or with scales that produced ordinal data.

RESULTS

Sixteen trials representing 17 relevant comparisons were included in this systematic review. Effect sizes were calculated as standardised mean differences because various muscles were studied and different outcome measures were used. Overall, electrical stimulation increased strength by a standardised mean difference (SMD) of 0.47 (95% CI 0.26 to 0.68) and this effect was maintained beyond the intervention period (SMD 0.33, 95% CI 0.07 to 0.60). Electrical stimulation also improved activity (SMD 0.30, 95% CI 0.05 to 0.56) and this effect was also maintained beyond the intervention period (SMD 0.38, 95% CI 0.09 to 0.66).

CONCLUSION

Cyclical electrical stimulation increases strength and improves activity after stroke. These benefits were maintained beyond the intervention period with a small-to-moderate effect size. The sustained effect on activity suggests that the benefits were incorporated into daily life. Review registration: PROSPERO (CRD42013003895).

Low force contractions induce fatigue consistent with muscle mRNA expression in people with spinal cord injury

Spinal cord injury (SCI) is associated with muscle atrophy, transformation of muscle fibers to a fast fatigable phenotype, metabolic inflexibility (diabetes), and neurogenic osteoporosis. Electrical stimulation of paralyzed muscle may mitigate muscle metabolic abnormalities after SCI, but there is a risk for a fracture to the osteoporotic skeletal system. The goal of this study was to determine if low force stimulation (3 Hz) causes fatigue of chronically paralyzed muscle consistent with selected muscle gene expression profiles. We tested 29 subjects, nine with a SCI and 20 without and SCI, during low force fatigue protocol. Three SCI and three non-SCI subjects were muscle biopsied for gene and protein expression analysis. The fatigue index (FI) was 0.21 ± 0.27 and 0.91 ± 0.01 for the SCI and non-SCI groups, respectively, supporting that the low force protocol physiologically fatigued the chronically paralyzed muscle. The post fatigue potentiation index (PI) for the SCI group was increased to 1.60 ± 0.06 (P <0.001), while the non-SCI group was 1.26 ± 0.02 supporting that calcium handling was compromised with the low force stimulation. The mRNA expression from genes that regulate atrophy and fast properties (MSTN, ANKRD1, MYH8, and MYCBP2) was up regulated, while genes that regulate oxidative and slow muscle properties (MYL3, SDHB, PDK2, and RyR1) were repressed in the chronic SCI muscle. MSTN, ANKRD1, MYH8, MYCBP2 gene expression was also repressed 3 h after the low force stimulation protocol. Taken together, these findings support that a low force single twitch activation protocol induces paralyzed muscle fatigue and subsequent gene regulation. These findings suggest that training with a low force protocol may elicit skeletal muscle adaptations in people with SCI.

Variation in venom yield and protein concentration of the centipedes Scolopendra polymorpha and Scolopendra subspinipes

Venom generally comprises a complex mixture of compounds representing a non-trivial metabolic expense. Accordingly, natural selection should fine-tune the amount of venom carried within an animal's venom gland(s). The venom supply of scolopendromorph centipedes likely influences their venom use and has implications for the severity of human envenomations, yet we understand very little about their venom yields and the factors influencing them. We investigated how size, specifically body length, influenced volume yield and protein concentration of electrically extracted venom in Scolopendra polymorpha and Scolopendra subspinipes. We also examined additional potential influences on yield in S. polymorpha, including relative forcipule size, relative mass, geographic origin (Arizona vs. California), sex, time in captivity, and milking history. Volume yield was linearly related to body length, and S. subspinipes yielded a larger length-specific volume than S. polymorpha. Body length and protein concentration were uncorrelated. When considering multiple influences on volume yield in S. polymorpha, the most important factor was body length, but yield was also positively associated with relative forcipule length and relative body mass. S. polymorpha from California yielded a greater volume of venom with a higher protein concentration than conspecifics from Arizona, all else being equal. Previously milked animals yielded less venom with a lower protein concentration. For both species, approximately two-thirds of extractable venom was expressed in the first two pulses, with remaining pulses yielding declining amounts, but venom protein concentration did not vary across pulses. Further study is necessary to ascertain the ecological significance of the factors influencing venom yield and how availability may influence venom use.

Electrical stimulation for difficult wounds: only an alternative procedure?

In the wound healing research, the exact mechanism of action of different modalities of electrical stimulation (ES) remains controversial and unresolved. In this study we discuss a particular ES, with a different type of waveform, corresponding to the principle of stochastic resonance. Between July 2008 and May 2010, 32 patients were enrolled and ES was applied to wounds using the bioelectrical signal therapy (BST) device (LifeWave, Petach Tiqwa, Israel). The outcome evaluated in group 1 (n = 21) was wound healing, while group 2 (n = 11) was evaluated for wound-related pain [Visual Number Scale (VNS) pain scale] during treatment. In group 1, 87% of the wounds closed in an average time of 97 days (range 10-150 days); three patients were lost to follow-up. In group 2, 45% of the patients experienced a complete pain disappearance after 7 days of treatment; 36% reported a reduction in VNS from 9·3 to 3·2 in 7 days; 19% stopped morphine-like painkillers after 2 weeks. The clinical application of the stochastic resonance enables the usage of easy-to-use, non-invasive, painless and pain-relief treatment. Our experience with ES has demonstrated the BST device to be a very good alternative in cases of small size defects, compared with other therapies such as surgery, dressing and negative pressure devices.

Neuromuscular electrical stimulation improves clinical and physiological function in COPD patients

BACKGROUND

Neuromuscular electrical stimulation (NMES) improves muscle performance and exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. In contrast, no study has assessed the effect of NMES on dynamic hyperinflation (DH) in COPD. This study investigated the effect of short-term, high-frequency NMES on DH in patients with COPD.

METHODS

Twenty patients were randomly allocated to either a NMES applied bilaterally to the quadriceps muscles (n = 11: 8 weeks, 5 days/week, twice/day, 45 min/session) or a control group (n = 09). All patients received respiratory physical therapy and stretching exercises. Free fat mass, pulmonary function, time to exercise tolerance (Tlim), 6-min walk test distance (6-MWTD), tumor necrosis factor (TNF-α) and β-endorphin levels, Borg dyspnea and leg score (BDS and BLS) and quality of life by the St. George's Respiratory Questionnaire score (SGRQ) were examined before and after the intervention.

RESULTS

Compared with the control group, NMES increased FEV1 and FEV1/FVC, 6-MWD and Tlim (P < 0.01) and reduced BDS and SGRQ (P < 0.01). Additionally, changes in the Tlim were positively correlated with respiratory improvements in FEV1 (rho = 0.48, P < 0.01). Also, NMES reduced TNF-α and increased β-endorphin levels, compared with the control group (P < 0.001).

CONCLUSION

In summary, 8 weeks of NMES promotes reduction of the perceived sensation of dyspnea during exercise in patients with COPD. This finding is accompanied by improvements in FEV1, exercise tolerance and quality of life, and DH. Interestingly, these findings may be associated with enhanced vasodilatory function and a reduction in inflammatory responses.

CLINICAL TRIAL REGISTRATION

NCT01695421.

Combined corticospinal and reticulospinal effects on upper limb muscles

Both the reticulospinal and corticospinal systems are known to control recruitment of upper limb muscles, yet no known studies have attempted to assess their combined effects in the same experiment in the awake, behaving primate. The purpose of this study is to present an approach for the analysis of the cooperative control from these two motor systems. Muscle responses to electrical stimulation in the reticulospinal system and corticospinal system alone or in combination were studied. The responses were categorized based on simple neural circuits that could explain the interactions of these systems. Five such circuits were identified that could explain 86% of the observed patterns of combined recruitment during stimulation. Improved understanding of the cooperation between these motor systems could provide insight for development of better rehabilitation approaches for stroke patients and others with movement disorders.

Wireless micro current stimulation--an innovative electrical stimulation method for the treatment of patients with leg and diabetic foot ulcers

Clinical experience with a new electrical stimulation (ES) technique, the wireless micro current stimulation (WMCS), for the treatment of chronic wounds is described. WMCS transfers the current to any surface wound from a distance, by using oxygen's and nitrogen's ability to exchange electrons. We studied 47 patients with hard-to-heal wounds. Patients with venous, arterial and mixed leg ulcers were predominant; other aetiologies such as diabetic foot lesions, pressure ulcers, vasculitis and pyoderma were also included. WMCS treatment protocol specified treatment twice or thrice per week, for 45-60 minutes per session, with 1·5 μA current intensity. Standard wound care was applied to all patients, including compression bandages, if necessary. Clear progress of wound healing, even after 2 weeks, was observed in all cases. The mean reduction of the wound surface after WMCS treatment was 95% in 8 weeks. Complete healing was achieved within 3 months for the majority of the cases. No clinical side effects were observed. WMCS technology significantly accelerated wound healing for patients with hard-to-heal wounds of different aetiologies. This new therapy offers multiple advantages compared with the previous methods of ES, as it is contactless, free of pain and very easy to use.

Electrical stimulation to promote osteogenesis using conductive polypyrrole films

In this study, we developed an electrical cell culture and monitoring device. Polypyrrole (PPy) films with different resistances were fabricated as conductive surfaces to investigate the effect of substrate-mediated electrical stimulation. The physical and chemical properties of the devices, as well as their biocompatibilities, were thoroughly evaluated. These PPy films had a dark but transparent appearance, on which the surface cells could be easily observed. After treating with the osteogenic medium, rat bone marrow stromal cells cultured on the PPy films differentiated into osteoblasts. The cells grown on the PPy films had up-regulated osteogenic markers, and an alkaline phosphatase activity assay showed that the PPy films accelerated cell differentiation. Alizarin red staining and calcium analysis suggested that the PPy films promoted osteogenesis. Finally, PPy films were subjected to a constant electric field to elucidate the effect of electrical stimulation on osteogenesis. Compared with the untreated group, electrical stimulation improved calcium deposition in the extracellular matrix. Furthermore, PPy films with lower resistances allowed larger currents to stimulate the surface cells, which resulted in higher levels of mineralization. Overall, these results indicated that this system exhibited superior electroactivity with controllable electrical resistance and that it can be coated directly to produce medical devices with a transparent appearance, which should be beneficial for research on electrical stimulation for tissue regeneration.

Median nerve fascicular anatomy as a basis for distal neural prostheses

INTRODUCTION

Functional electrical stimulation (FES) serves as a possible therapy to restore missing motor functions of peripheral nerves by means of cuff electrodes. FES is established for improving lower limb function. Transferring this method to the upper extremity is complex, due to a lack of anatomical data on the physiological configuration of nerve fascicles. Our study's aim was to provide an anatomical basis for FES of the median nerve in the distal forearm and hand.

METHODS

We investigated 21 distal median nerves from 12 body donors. The peripheral fascicles were traced back by removing the external and interfascicular epineurium and then assigned to 4 quadrants.

RESULTS

A distinct motor and sensory distribution was observed. The fascicles innervating the thenar eminence and the first lumbrical muscle originated from the nerves' radial parts in 82%. The fascicle supplying the second lumbrical muscle originated from the ulnar side in 78%. No macroscopically visible plexus formation was observed for the distal median nerve in the forearm.

CONCLUSIONS

The findings on the distribution of the motor branches of the median nerve and the missing plexus formation may likely serve as an anatomical basis for FES of the distal forearm. However, due to the considerable variability of the motor branches, cuff electrodes will need to be adapted individually in FES. Taking into account the sensory distribution of the median nerve, FES may also possibly be applied in the treatment of regional pain syndromes.

Rewarding effects of the electrical stimulation of the parabrachial complex: taste or place preference?

The lateral parabrachial complex has been related to various emotional-affective processes. It has been shown that electrical stimulation of the external Lateral Parabrachial (LPBe) nucleus can induce reinforcing effects in place preference and taste discrimination tasks but does not appear to support self-stimulation. This study examined the relative relevance of place and taste stimuli after electrical stimulation of the LPBe nucleus. A learning discrimination task was conducted that simultaneously included both sensory indexes (taste and place) in order to determine the preference of animals for one or the other. After a taste stimulus reversal task, the rewarding effect of stimulation was found to be preferentially associated with place. These results are discussed in the context of the rewarding action and biological constraints induced by different natural and artificial reinforcing agents.

Numerical investigation into blood clotting at the bone-dental implant interface in the presence of an electrical stimulus

The insertion of a dental implant activates a sequence of wound healing events ending with bone formation and implant osseointegration. This sequence starts with the blood coagulation process and the formation of a fibrin network that detains spilt blood. Fibrin formation can be simplified as the kinetic reaction between thrombin and fibrinogen preceding the conversion of fibrinogen into fibrin. Based on experimental observations of the electrical properties of these molecules, we present a hypothesis for the mechanism of a static electrical stimulus in controlling the formation of the blood clot. Specifically, the electrical stimulus increases the fibrin network formation in such a way that a preferential region of higher fibrin density is obtained. This hypothesis is validated by means of a numerical model for the blood clot formation at the bone-dental implant interface. Numerical results compare favorably to experimental observations for blood clotting with and without the static electrical stimulus. It is concluded that the density of the fibrin network depends on the strength of the static electrical stimulus, and that the blood clot formation has a preferential direction of formation in the presence of the electrical signal.

Combined arm stretch positioning and neuromuscular electrical stimulation during rehabilitation does not improve range of motion, shoulder pain or function in patients after stroke: a randomised trial

QUESTION

Does static stretch positioning combined with simultaneous neuromuscular electrical stimulation (NMES) in the subacute phase after stroke have beneficial effects on basic arm body functions and activities?

DESIGN

Multicentre randomised trial with concealed allocation, assessor blinding, and intention-to-treat analysis.

PARTICIPANTS

Forty-six people in the subacute phase after stroke with severe arm motor deficits (initial Fugl-Meyer Assessment arm score ≤ 18).

INTERVENTION

In addition to conventional stroke rehabilitation, participants in the experimental group received arm stretch positioning combined with motor amplitude NMES for two 45-minute sessions a day, five days a week, for eight weeks. Control participants received sham arm positioning (ie, no stretch) and sham NMES (ie, transcutaneous electrical nerve stimulation with no motor effect) to the forearm only, at a similar frequency and duration.

OUTCOME MEASURES

The primary outcome measures were passive range of arm motion and the presence of pain in the hemiplegic shoulder. Secondary outcome measures were severity of shoulder pain, restrictions in performance of activities of daily living, hypertonia, spasticity, motor control and shoulder subluxation. Outcomes were assessed at baseline, mid-treatment, at the end of the treatment period (8 weeks) and at follow-up (20 weeks).

RESULTS

Multilevel regression analysis showed no significant group effects nor significant time × group interactions on any of the passive range of arm motions. The relative risk of shoulder pain in the experimental group was non-significant at 1.44 (95% CI 0.80 to 2.62).

CONCLUSION

In people with poor arm motor control in the subacute phase after stroke, static stretch positioning combined with simultaneous NMES has no statistically significant effects on range of motion, shoulder pain, basic arm function, or activities of daily living.

TRIAL REGISTRATION

NTR1748.

Electrical Stimulation of NIH-3T3 Cells with Platinum-PEDOT-Electrodes Integrated in a Bioreactor

The objective of this work involves the development and integration of electrodes for the electrical stimulation of cells within a bioreactor. Electrodes need to fit properties such as biocompatibility, large reversible charge transfer and high flexibility in view of their future application as implants on the tympanic membrane. Flexible thin-film platinum-poly(3,4-ethylene-dioxythiophene)-electrodes on a poly(ethylene terephthalate)-foil manufactured using microsystems technology were integrated into a bioreactor based on the design of a 24 well plate. The murine fibroblast cell line NIH-3T3 was cultured on the foil electrodes and the cells were stimulated with direct voltage and unipolar pulsed voltage. The amplitude, the pulse length and the ratio of pulse to pause were varied. The stimulated cells were stained in order to determine the angle between the cell cleavage plane of the dividing cells and the vector of the electric field. These angles were subsequently used to calculate the polarization index, which is a measure of the orientation of the metaphase plane of dividing cells that occurs for example during wound healing or embryonic morphogenesis.

Impedance changes in chronically implanted and stimulated cochlear implant electrodes

OBJECTIVES

Electrode impedance increases following implantation and undergoes transitory reduction with onset of electrical stimulation. The studies in this paper measured the changes in access resistance and polarization impedance in vivo before and following electrical stimulation, and recorded the time course of these changes.

DESIGN

Impedance measures recorded in (a) four cats following 6 months of cochlear implant use, and (b) three cochlear implant recipients with 1.5-5 years cochlear implant experience.

RESULTS

Both the experimental and clinical data exhibited a reduction in electrode impedance, 20 and 5% respectively, within 15-30 minutes of stimulation onset. The majority of these changes occurred through reduction in polarization impedance. Cessation of stimulation was followed by an equivalent rise in impedance measures within 6-12 hours.

CONCLUSIONS

Stimulus-induced reductions in impedance exhibit a rapid onset and are evident in both chronic in vivo models tested, even several years after implantation. Given the impedance changes were dominated by the polarization component, these findings suggest that the electrical stimulation altered the electrode surface rather than the bulk tissue and fluid in the cochlea.

The effects of neuromuscular electrical stimulation on pharyngeal transit time

[Purpose] The purpose of this study was to identify the effects of Neuromuscular Electrical Stimulation (NMES) on pharyngeal transit time. [Subjects] Subjects were divided into normal old persons aged over 70 (N=18), and normal young persons aged under 30 (N=10). [Method] We measured the Pharyngeal Transit Time (PTT) to determine their swallowing characteristics. NMES was used to stimulate old group's suprahyoid and infrahyoid muscles 60 minutes a day, 5 days a week for 2 weeks using four electrodes. We used SPSS version 14.0 to analyze and compare the data between the 2 groups. [Results] After NMES, PTT of the normal old group became significantly shorter. PTT was much shorter, but was still longer than that of the normal young group. [Conclusion] The PTTs of the two groups classified by age were significantly different.

Biomimetic scaffold combined with electrical stimulation and growth factor promotes tissue engineered cardiac development

Toward developing biologically sound models for the study of heart regeneration and disease, we cultured heart cells on a biodegradable, microfabricated poly(glycerol sebacate) (PGS) scaffold designed with micro-structural features and anisotropic mechanical properties to promote cardiac-like tissue architecture. Using this biomimetic system, we studied individual and combined effects of supplemental insulin-like growth factor-1 (IGF-1) and electrical stimulation (ES). On culture day 8, all tissue constructs could be paced and expressed the cardiac protein troponin-T. IGF-1 reduced apoptosis, promoted cell-to-cell connectivity, and lowered excitation threshold, an index of electrophysiological activity. ES promoted formation of tissue-like bundles oriented in parallel to the electrical field and a more than ten-fold increase in matrix metalloprotease-2 (MMP-2) gene expression. The combination of IGF-1 and ES increased 2D projection length, an index of overall contraction strength, and enhanced expression of the gap junction protein connexin-43 and sarcomere development. This culture environment, designed to combine cardiac-like scaffold architecture and biomechanics with molecular and biophysical signals, enabled functional assembly of engineered heart muscle from dissociated cells and could serve as a template for future studies on the hierarchy of various signaling domains relative to cardiac tissue development.

Amygdala-mediated enhancement of memory for specific events depends on the hippocampus

Emotional events are often remembered better than neutral events, a type of memory prioritization by affective salience that depends on the amygdala. Studies with rats have indicated that direct activation of the basolateral complex of the amygdala (BLA) can enhance memory for neutral events, and if the activation is brief and temporally targeted, can do so in a way that benefits memories for specific events. The essential targets of BLA activation in the case of event-specific memory enhancement were unknown, but the hippocampus was known to receive direct projections from the BLA and to support memory for events. In the present study, rats received counterbalanced infusions of either muscimol, a GABAA receptor agonist, or saline into the hippocampus prior to performing a novel object recognition memory task during which initial encounters with some of the objects were immediately followed by brief electrical stimulation to the BLA. When memory was tested 1day later in the saline condition, rats remembered these objects well but showed no memory for objects for which the initial encounter had not been followed by BLA stimulation. In contrast, no benefit to memory of BLA stimulation was observed in the muscimol condition. The results indicated that brief activation of the BLA can prioritize memories for events by enhancing memory for some object encounters but not others and that this benefit to memory depends on interactions between the amygdala and the hippocampus.

Neural circuits with long-distance axon tracts for determining functional connectivity

The cortical circuitry in the brain consists of structurally and functionally distinct neuronal assemblies with reciprocal axon connections. To generate cell culture-based systems that emulate axon tract systems of an in vivo neural network, we developed a living neural circuit consisting of compartmentalized neuronal populations connected by arrays of two millimeter-long axon tracts that are integrated on a planar multi-electrode array (MEA). The millimeter-scale node-to-node separation allows for pharmacological and electrophysiological manipulations to simultaneously target multiple neuronal populations. The results show controlled selectivity of dye absorption by neurons in different compartments. MEA-transmitted electrical stimulation of targeted neurons shows ∼46% increase of intracellular calcium levels with 20 Hz stimulation, but ∼22% decrease with 2k Hz stimulation. The unique feature of long distance axons promotes in vivo-like fasciculation. These axon tracts are determined to be inhibitory afferents by showing increased action potential firing of downstream node upon selective application of γ-aminobutyric acid (GABA) to the upstream node. Together, this model demonstrates integrated capabilities for assessing multiple endpoints including axon tract tracing, calcium influx, network architecture and activities. This system can be used as a multi-functional platform for studying axon tract-associated CNS disorders in vitro, such as diffuse axonal injury after brain trauma.

The effects of assisted ergometer training with a functional electrical stimulation on exercise capacity and functional ability in subacute stroke patients

OBJECTIVE

To determine if assistive ergometer training can improve the functional ability and aerobic capacity of subacute stroke patients and if functional electrical stimulation (FES) of the paretic leg during ergometer cycling has additional effects.

METHODS

Sixteen subacute stroke patents were randomly assigned to the FES group (n=8) or the control group (n=8). All patients underwent assistive ergometer training for 30 minutes (five times per week for 4 weeks). The electrical stimulation group received FES of the paretic lower limb muscles during assistive ergometer training. The six-minute walk test (6MWT), Berg Balance Scale (BBS), and the Korean version of Modified Barthel Index (K-MBI) were evaluated at the beginning and end of treatment. Peak oxygen consumption (Vo2peak), metabolic equivalent (MET), resting and maximal heart rate, resting and maximal blood pressure, maximal rate pressure product, submaximal rate pressure product, submaximal rate of perceived exertion, exercise duration, respiratory exchange ratio, and estimated anaerobic threshold (AT) were determined with the exercise tolerance test before and after treatment.

RESULTS

At 4 weeks after treatment, the FES assistive ergometer training group showed significant improvements in 6MWT (p=0.01), BBS (p=0.01), K-MBI (p=0.01), Vo2peak (p=0.02), MET (p=0.02), and estimated AT (p=0.02). The control group showed improvements in only BBS (p=0.01) and K-MBI (p=0.02). However, there was no significant difference in exercise capacity and functional ability between the two groups.

CONCLUSION

This study demonstrated that ergometer training for 4 weeks improved the functional ability of subacute stroke patients. In addition, aerobic capacity was improved after assisted ergometer training with a FES only.

Minimal electrical stimulation is effective in low stressed and well fed cattle

Four groups of carcasses of eighty grain fed low stressed steers (~12 months old, 240 kg carcass weight) received no stimulation or had low voltage stimulation for 15, 45 and 90 s. M. longissimus was aged for 2 and 14 days at 2 °C. Shear force, sarcomere length, water holding capacity, purge, muscle fibre detachment, sarcomere breaks and colour shelf life over 7 days was measured. Both 45 s and 90 s stimulated samples completed rigor above 35 °C and 15s stimulated and non-stimulated samples below 35 °C. The greatest muscle fibre detachment occurred for 15s stimulated samples which were the most tender at all times with non-stimulated samples toughest at 2 days of ageing and all samples being tender at 14 days of ageing. The 45 and 90 s stimulated samples consistently exhibited a brighter red colour at 2 days of ageing with no differences in colour intensity for the samples aged 14 days.

Efficacy of electrical stimulation for spinal fusion: a meta-analysis of fusion rate

BACKGROUND CONTEXT

Many clinical studies have demonstrated the effectiveness of electrical stimulation as an adjunct to spinal arthrodesis. However, there is a paucity of comparative data among different electrical stimulation techniques.

PURPOSE

To compare the efficacy of three electrical stimulation methods for spinal fusion based on the literature review.

SAMPLE

Twenty-one articles, meeting all the inclusion criteria, were selected. A total of 1,381 patients were evaluated.

STUDY DESIGN

Systematic literature review and meta-analysis.

OUTCOME MEASURES

Fusion rates were determined using radiography or computed tomography.

METHODS

A systematic literature review was conducted on spinal fusion surgeries with the aid of electrical stimulation devices. Only studies applying radiography or computed tomography for fusion assessment were included. Study groups were divided based on electrical stimulation types and were further grouped by other patient characteristics. Pooled estimates and 95% confidence intervals (CIs) were calculated by random-effects meta-analysis.

RESULTS

The pooled fusion rate for all studies was 85% (95% CI, 79-90). There were 14 direct current, 1 capacitive coupling (CC), and 10 inductive coupling studies in our analysis, with combined fusion rate of 85% (95% CI, 76-91), 90% (95% CI, 83-95), and 85% (95% CI, 74-93), respectively. There were no statistically significant differences among the three electrical stimulation methods. Further subgroup analysis suggested that age, sex, smoking status, surgery type, fusion levels, fusion column, implant use, and graft type did not significantly influence the fusion rate.

CONCLUSIONS

The three types of electrical stimulation devices had similar clinical efficacy in promoting bone growth for spinal fusion. The results for CC stimulation should be applied with caution as only one relevant study was identified.

Structural and functional plasticity in long-term cultures of adult ventricular myocytes

Cultured heart cells have long been valuable for characterizing biological mechanism and disease pathogenesis. However, these preparations have limitations, relating to immaturity in key properties like excitation-contraction coupling and β-adrenergic stimulation. Progressive attenuation of the latter is intimately related to pathogenesis and therapy in heart failure. Highly valuable would be a long-term culture system that emulates the structural and functional changes that accompany disease and development, while concurrently permitting ready access to underlying molecular events. Accordingly, we here produce functional monolayers of adult guinea-pig ventricular myocytes (aGPVMs) that can be maintained in long-term culture for several weeks. At baseline, these monolayers exhibit considerable myofibrillar organization and a significant contribution of sarcoplasmic reticular (SR) Ca(2+) release to global Ca(2+) transients. In terms of electrical signaling, these monolayers support propagated electrical activity and manifest monophasic restitution of action-potential duration and conduction velocity. Intriguingly, β-adrenergic stimulation increases chronotropy but not inotropy, indicating selective maintenance of β-adrenergic signaling. It is interesting that this overall phenotypic profile is not fixed, but can be readily enhanced by chronic electrical stimulation of cultures. This simple environmental cue significantly enhances myofibrillar organization as well as β-adrenergic sensitivity. In particular, the chronotropic response increases, and an inotropic effect now emerges, mimicking a reversal of the progression seen in heart failure. Thus, these aGPVM monolayer cultures offer a valuable platform for clarifying long elusive features of β-adrenergic signaling and its plasticity.

Cardiac stem cells with electrical stimulation improve ischaemic heart function through regulation of connective tissue growth factor and miR-378

AIMS

In this study, we investigated whether pre-conditioning (PC) by electrical stimulation (EleS) induces cytoprotective effect on cardiac stem cells (CSCs) and determined its underlying molecular mechanisms.

METHODS AND RESULTS

Sca-1(+) CSCs were isolated from male C57BL6 mice (12 weeks) hearts. PC of CSCs with EleS ((EleS)CSCs) was carried out for 3 h at 1.5 V followed by exposure to 300 µM H2O2 for 5 h. Cytoprotective effects and cell adhesion ability were significantly increased by EleS as evaluated by transferase-mediated dUTP nick-end labelling (TUNEL), lactate dehydrogenase (LDH) release assay, and adhesion assay. EleS increased phosphorylation of AKT, focal adhesion kinase (FAK), and glycogen synthase kinase (GSK3β), as well as decreased caspase-3 cleavage. Interestingly, inhibition of AKT or FAK abolished the pro-survival effects of EleS. We found that connective tissue growth factor (Ctgf) was responsible for EleS-induced CSC survival and adhesion.The survival rate of (EleS)CSCs after transplantation in the infarcted myocardium was significantly increased together with improvement in cardiac function. Importantly, knockdown of Ctgf abolished EleS-induced cytoprotective effects and recovery of cardiac function. Furthermore, we identified miR-378 as a potential Ctgf regulator in (EleS)CSCs.

CONCLUSION

EleS enhanced CSC survival in vitro and in vivo as well as functional recovery of the ischaemic heart through an AKT/FAK/CTGF signalling pathway. It is suggested that Ctgf and miR-378 are novel therapeutic targets for stem cell-based therapy.

Neuromuscular electrostimulation viathe common peroneal nerve promotes lower limb blood flow in a below-kneecast: A potential for thromboprophylaxis

Objectives

We aimed to examine the characteristics of deep venous flow in the leg in a cast and the effects of a wearable neuromuscular stimulator (geko; FirstKind Ltd) and also to explore the participants’ tolerance of the stimulator.

Methods

This is an open-label physiological study on ten healthy volunteers. Duplex ultrasonography of the superficial femoral vein measured normal flow and cross-sectional area in the standing and supine positions (with the lower limb initially horizontal and then elevated). Flow measurements were repeated during activation of the geko stimulator placed over the peroneal nerve. The process was repeated after the application of a below-knee cast. Participants evaluated discomfort using a questionnaire (verbal rating score) and a scoring index (visual analogue scale).

Results

The geko device was effective in significantly increasing venous blood flow in the lower limb both with a plaster cast (mean difference 11.5 cm/sec^-1; p = 0.001 to 0.13) and without a plaster cast (mean difference 7.7 cm/sec^-1; p = 0.001 to 0.75). Posture also had a significant effect on peak venous blood flow when the cast was on and the geko inactive (p = 0.003 to 0.69), although these differences were less pronounced than the effect of the geko (mean difference 3.1 cm/sec^-1 (-6.5 to 10)). The geko device was well tolerated, with participants generally reporting only mild discomfort using the device.

Conclusion

The geko device increases venous blood flow in the lower limb, offering a potential mechanical thromboprolylaxis for patients in a cast.

Cite this article: Bone Joint Res 2013;2:179–85.

The modulation of forward propulsion, vertical support, and center of pressure by the plantarflexors during human walking

The gastrocnemius and soleus both contribute to the ankle plantarflexor moment during the mid- and terminal stance phases of gait. The gastrocnemius also generates a knee flexion moment that may lead to dynamic function that is unique from the soleus. This study used a muscle stimulation protocol to experimentally compare the contributions of individual plantarflexors to vertical support, forward propulsion and center of pressure (CoP) movement during normal gait. Twenty subjects walked on an instrumented treadmill at self-selected speeds with stimulating surface electrodes affixed over the medial gastrocnemius and soleus muscles. Short duration pulse trains (90 ms) were used to stimulate either the gastrocnemius or soleus at 20% or 30% of the gait cycle (GC) of random strides. Changes in ground reactions between stimulated and non-stimulated strides were evaluated to characterize the influence of each muscle on whole body movement during mid- (stimulation onset at 20% GC) and late (30% GC) stance. The gastrocnemius and soleus each induced an increase in vertical support and anterior progression of the CoP in mid-stance. However, late stance gastrocnemius activity induced forward acceleration, while both mid- and terminal stance soleus activity induced braking of forward velocity. The results suggested that the individual plantarflexors exhibit unique functions during normal gait, with the two muscles having opposite effects on forward propulsion. These empirical results are important both for enhancing the veracity of models used to predict muscle function in gait and also clinically as physicians seek to normalize gait in patients with plantarflexor dysfunction.