Calcium influx differentially regulates migration velocity and directedness in response to electric field application.

Neural precursor cells (NPCs) respond to externally applied direct current electrical fields (DCEFs) by undergoing rapid and directed migration toward the cathode in a process known as galvanotaxis. It is unknown if the underlying mechanisms of galvanotactic migration is common to non-electrosensitive cells and if so, how NPCs and other galvanotactic cells sense and transduce electrical fields into cellular motility. In this study, we show that distinct aspects of NPC galvanotactic migration: motility (quantified through |velocity|) and directedness, are differentially regulated by calcium. We use low-Ca2+ culture conditions; an intracellular Ca2+ chelator; and voltage gated calcium channel (VGCC) inhibitors to specific channels expressed on NPCs, to demonstrate the role of Ca2+ influx in DCEF-induced NPC migration. Consistent with existing literature, we show Ca2+ is involved in F-actin polymerization that lengthens NPC membrane protrusions necessary for cellular motility. However, inhibiting Ca2+ results in reduced velocity but has no effect on DCEF-induced directedness. This dissociation between velocity and directedness reveal that these migration parameters can be independently regulated, thus suggesting a parallel process of sensing DCEFs by NPCs.

Exploring the determinants of fracture risk among individuals with spinal cord injury.

UNLABELLED: In this cross-sectional study, we found that areal bone mineral density (aBMD) at the knee and specific tibia bone geometry variables are associated with fragility fractures in men and women with chronic spinal cord injury (SCI). INTRODUCTION: Low aBMD of the hip and knee regions have been associated with fractures among individuals with chronic motor complete SCI; however, it is unclear whether these variables can be used to identify those at risk of fracture. In this cross-sectional study, we examined whether BMD and geometry measures are associated with lower extremity fragility fractures in individuals with chronic SCI. METHODS: Adults with chronic [duration of injury ≥ 2 years] traumatic SCI (C1-L1 American Spinal Cord Injury Association Impairment Scale A-D) reported post injury lower extremity fragility fractures. Dual-energy X-ray absorptiometry (DXA) was used to measure aBMD of the hip, distal femur, and proximal tibia regions, while bone geometry at the tibia was assessed using peripheral quantitative computed tomography (pQCT). Logistic regression and univariate analyses were used to identify whether clinical characteristics or bone geometry variables were associated with fractures. RESULTS: Seventy individuals with SCI [mean age (standard deviation [SD]), 48.8 (11.5); 20 females] reported 19 fragility fractures. Individuals without fractures had significantly greater aBMD of the hip and knee regions and indices of bone geometry. Every SD decrease in aBMD of the distal femur and proximal tibia, trabecular volumetric bone mineral density, and polar moment of inertia was associated with fracture prevalence after adjusting for motor complete injury (odds ratio ranged from 3.2 to 6.1). CONCLUSION: Low knee aBMD and suboptimal bone geometry are significantly associated with fractures. Prospective studies are necessary to confirm the bone parameters reported to predict fracture risk in individuals with low bone mass and chronic SCI.

Use of screening to recruitment ratios as a tool for planning and implementing spinal cord injury rehabilitation research.

STUDY DESIGN: Descriptive report. OBJECTIVES: To describe screening to recruitment (S:R) ratios and discuss their use for planning and implementing research among individuals with spinal cord injury (SCI) . SETTING: Toronto, Ontario, Canada. METHODS: We calculated S:R ratios for SCI research by study methodology and nature of the exposure/intervention for 25 studies previously conducted in a tertiary SCI rehabilitation facility. Study methodologies included ten randomized controlled trials (RCTs), nine cohort studies and six panel studies. Exposures included seven rehabilitation interventions, and three drug studies, ten telephone interviews/chart abstractions (TI/CA) and five surveys. A S:R ratio was calculated for each study methodology, and exposure type, by dividing the number of consenting individuals who underwent screening by the number of eligible recruited participants enrolled in the study. RESULTS: In terms of design, RCTs had the highest median S:R ratio (3:1), followed by cohort studies (2:1) and panel studies (2:1). In terms of intervention type, drug studies had the largest median S:R ratio (5:1), followed in descending order by rehabilitation studies (2:1), TI/CAs studies (2:1) and surveys (2:1). CONCLUSIONS: Reported S:R ratios varied substantially with study methodology and the associated study intervention exposure. Awareness of S:R ratios may assist researchers in estimating recruitment timelines, personnel needs and study budgets for a required sample size based on the planned study methodology and intended study exposure. We advocate for the routine reporting of S:R ratios to inform the success of future SCI research.

International spinal cord injury upper extremity basic data set.

OBJECTIVE: To develop an International Spinal Cord Injury (SCI) Upper Extremity Basic Data Set as part of the International SCI Data Sets, which facilitates consistent collection and reporting of basic upper extremity findings in the SCI population. SETTING: International. METHODS: A first draft of a SCI Upper Extremity Data Set was developed by an international working group. This was reviewed by many different organisations, societies and individuals over several months. A final version was created. VARIABLES: The final version of the International SCI Upper Extremity Data Set contains variables related to basic hand-upper extremity function, use of assistive devices, SCI-related complications to upper extremity function and upper extremity/hand reconstructive surgery. Instructions for data collection and the data collection form are freely available on the ISCoS website (www.iscos.org.uk). CONCLUSION: The International SCI Upper Extremity Basic Data Set will facilitate consistent collection and reporting of basic upper extremity findings in the SCI population.

Feasibility and efficacy of upper limb robotic rehabilitation in a subacute cervical spinal cord injury population.

STUDY DESIGN: Multi-center pilot study. OBJECTIVES: To investigate the use of an upper limb robotic rehabilitation device (Armeo Spring, Hocoma AG, Switzerland) in a subacute cervical spinal cord injury (SCI) population. SETTING: Two Canadian inpatient rehabilitation centers. METHODS: Twelve subjects (motor level C4-C6, ASIA Impairment Scale A-D) completed the training, which consisted of 16.1±4.6 sessions over 5.2±1.4 weeks. Two types of outcomes were recorded: (1) feasibility of incorporating the device into an inpatient rehabilitation program (compliance with training schedule, reduction in therapist time required and subject questionnaires) and (2) efficacy of the robotic rehabilitation for improving functional outcomes (Graded and Redefined Assessment of Strength, Sensibility and Prehension (GRASSP), action research arm test, grip dynamometry and range of motion). RESULTS: By the end of the training period, the robot-assisted training was shown to require active therapist involvement for 25±11% (mean±s.d.) of the total session time. In the group of all subjects and in a subgroup composed of motor-incomplete subjects, no statistically significant differences were found between intervention and control limbs for any of the outcome measures. In a subgroup of subjects with partial hand function at baseline, the GRASSP-Sensibility component showed a statistically significant increase (6.0±1.6 (mean±s.e.m.) point increase between baseline and discharge for the intervention limbs versus 1.9±0.9 points for the control limbs). CONCLUSION: The pilot results suggest that individuals with some preserved hand function after SCI may be better candidates for rehabilitation training using the Armeo Spring device.

Positive effect of balance training with visual feedback on standing balance abilities in people with incomplete spinal cord injury.

OBJECTIVES: (1) To evaluate the learning potential and performance improvements during standing balance training with visual feedback (VBT) in individuals with incomplete spinal cord injury (SCI) and (2) to determine whether standing static and dynamic stability during training-irrelevant tasks can be improved after the VBT. SETTING: National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan. METHODS: Six participants with chronic motor and sensory incomplete SCI who were able to stand for at least 5 min without any form of assistive device performed the VBT, 3 days per week, for a total of 12 sessions. During the training, participants stood on a force platform and were instructed to shift their center of pressure in the indicated directions as represented by a cursor on a monitor. The performance and the rate of learning were monitored throughout the training period. Before and after the program, static and dynamic stability was assessed. RESULTS: All participants showed substantial improvements in the scores, which varied between 236±94 and 130±14% of the initial values for different exercises. The balance performance during training-irrelevant tasks was significantly improved: for example, the area inside the stability zone after the training reached 221±86% of the pre-training values. CONCLUSION: Postural control can be enhanced in individuals with incomplete SCI using VBT. All participants showed substantial improvements during standing in both game performance and training-irrelevant tasks after the VBT.

Control of a neuroprosthesis for grasping using off-line classification of electrocorticographic signals: case study.

STUDY DESIGN: Proof of concept study to control a neuroprosthesis for grasping using identification of arm movements from ECoG signals. OBJECTIVE: To test the feasibility of using electrocorticographic (ECoG) signals as a control method for a neuroprosthesis for grasping. SETTING: Acute care hospital, Toronto Western Hospital and spinal cord injury (SCI) rehabilitation centre, Toronto Rehabilitation Institute, Lyndhurst Centre. Both hospitals are located in Toronto, Canada. METHODS: Two subjects participated in this study. The first subject had subdural electrodes implanted on the motor cortex for the treatment of essential tremor (ET). ECoG signals were recorded while the subject performed specific arm movements. The second subject had a complete SCI at C6 level (ASIA B score) and was fitted with a neuroprosthesis, capable of identifying arm movements from ECoG signals off-line, for grasping. To operate the neuroprosthesis, subject 2 issued a command that would trigger the release of a randomly selected ECoG signal recorded from subject 1, associated with a particular arm movement. The neuroprosthesis identified which arm movement was performed at the time of recording and used that information to trigger the stimulation sequence. A correct ECoG classification resulted in the neuroprosthesis producing the correct hand function (that is grasp and release). RESULTS: The neuroprosthesis classified ECoG signals correctly delivering the correct stimulation strategy with 94.5% accuracy. CONCLUSIONS: The feasibility of using ECoG signals as a control strategy for a neuroprosthesis for grasping was shown.

Functional electrical stimulation of walking: function, exercise and rehabilitation.

For nearly half a century, functional electrical stimulation (FES) has been used to restore walking for people with paralysis and muscle weakness due to stroke and spinal cord injury. The first applications of the technology were intended to permanently replace lost neuromuscular function. Later, FES-assisted walking was found to have therapeutic benefits that include increased muscle strength, cardiovascular fitness and improved gait function that could be maintained after use of FES was terminated. In this review, we examine some of the major FES-assisted walking systems that have been developed for experimental and commercial purposes over the last four and a half decades, including foot drop stimulators, multichannel stimulators and hybrid orthotic systems.

Dynamic force-sharing in multi-digit task.

BACKGROUND: Dynamic hand grasping implies sophisticated motor coordination. Most knowledge on motor synergies used in grasping is deduced from experiments based on static precision grip. This experiment was aimed at better understanding the mechanisms of finger force-sharing in an active, dynamic hand task under repetitive strain conditions. METHODS: A multi-digit task consisting of holding a cylinder with the digit tips, in which the thumb and the finger opposed each other, was investigated during repetitive unidirectional wrist flexion and extension cyclic motion. Finger and thumb forces and wrist angular position were simultaneously recorded during repetitive wrist motion against 0.3-0.6 Nm load in 10 healthy adults. FINDINGS: Load torques acting during wrist movements produced in-phase increases of the thumb and the finger forces with the wrist extension and the wrist flexion, respectively. Digit forces increased proportionally to the applied load. The alternating rise of thumb and finger forces changed instantaneously at the end of the flexion and extension phases of the movement, respectively. Six subjects predominantly used the index finger, two the middle finger, one the ring finger, and the remaining one used the small finger during wrist flexion against 0.6 Nm to perform the task. Variations among individual finger forces were negatively correlated during the phase of constant rotational velocity of the wrist flexion. Repeated measures ANOVA revealed that the percentage of individual finger contribution to the total fingers' force significantly varied during the wrist flexion (P<0.0001) and among wrist flexion cycles (P<0.0001) in each subject. INTERPRETATION: Variations in finger force-sharing among cycles were not necessitated by task dependent activities, as the task was identical. These findings indicated that motor coordination of repeated multi-finger task allowed redundant solutions in finger force-sharing. The force-sharing variation may reflect a minimal intervention principle of the central nervous system controlling only the goal-directed parameters and might help to prevent muscle fatigue in repetitive tasks through modulation of activity in multi-digit muscles.

A reliable gait phase detection system.

A new highly reliable gait phase detection system, which can be used in gait analysis applications and to control the gait cycle of a neuroprosthesis for walking, is described. The system was designed to detect in real-time the following gait phases: stance, heel-off, swing, and heel-strike. The gait phase detection system employed a gyroscope to measure the angular velocity of the foot and three force sensitive resistors to assess the forces exerted by the foot on the shoe sole during walking. A rule-based detection algorithm, which was running on a portable microprocessor board, processed the sensor signals. In the presented experimental study ten able body subjects and six subjects with impaired gait tested the device in both indoor and outdoor environments (0-25 degrees C). The subjects were asked to walk on flat and irregular surfaces, to step over small obstacles, to walk on inclined surfaces, and to ascend and descend stairs. Despite the significant variation in the individual walking styles the system achieved an overall detection reliability above 99% for both subject groups for the tasks involving walking on flat, irregular, and inclined surfaces. In the case of stair climbing and descending tasks the success rate of the system was above 99% for the able body subjects and above 96 % for the subjects with impaired gait. The experiments also showed that the gait phase detection system, unlike other similar devices, was insensitive to perturbations caused by nonwalking activities such as weight shifting between legs during standing, feet sliding, sitting down, and standing up.

Effect of fentanyl, ketamine and thalamonal on some biochemical parameters in ethanol-treated and untreated dogs.

The effects of fentanyl, ketamine and thalamonal on some biochemical parameters of ethanol-treated and untreated dogs, were studied. The study was carried out on mongrel dogs. The animals were divided into two main groups: one which had free access to food and to 12% (v/v) ethanol, instead of water, and a control group which had food and water ad libitum. The animals in both groups were exposed to the action of anaesthetics for 3 h. The results show that, under the given experimental conditions, the anaesthetics did not significantly change the investigated parameters of blood and liver, either in ethanol-treated or untreated dogs. However, the action of ethanol caused remarkable changes in almost all the investigated parameters. An increased content of cytochrome P450 caused by the action of ethanol suggests possible changes in the metabolism of anaesthetics, which should be of concern to anaesthetists when dealing with patients potentially intoxicated with ethanol.

Effect of neuroleptics on ethanol-treated rats.

The subject of the present study is the effect of neuroleptic anaesthetics on sleeping time and some biochemical parameters of ethanol-treated and untreated rats. In one set of experiments involving four groups of animals, we studied how ethanol (12%, v/v) consumption for 10, 20 and 30 days influenced the sleeping time of animals after administration of a single dose of the investigated anaesthetics. In the other set of experiments, we studied the combined effect of 30 day ethanol consumption and each of the anaesthetics administered to the animals in multiple doses for 3 h, by determining the contents of cytochrome P450 and glutathione and the activities of glutathione peroxidase and lipid peroxidation. The results show that statistically significant changes of measured parameters are due to the action of ethanol and not of the neuroleptic anaesthetics.

Video game-based neuromuscular electrical stimulation system for calf muscle training: a case study.

A video game-based training system was designed to integrate neuromuscular electrical stimulation (NMES) and visual feedback as a means to improve strength and endurance of the lower leg muscles, and to increase the range of motion (ROM) of the ankle joints. The system allowed the participants to perform isotonic concentric and isometric contractions in both the plantarflexors and dorsiflexors using NMES. In the proposed system, the contractions were performed against exterior resistance, and the angle of the ankle joints was used as the control input to the video game. To test the practicality of the proposed system, an individual with chronic complete spinal cord injury (SCI) participated in the study. The system provided a progressive overload for the trained muscles, which is a prerequisite for successful muscle training. The participant indicated that he enjoyed the video game-based training and that he would like to continue the treatment. The results show that the training resulted in a significant improvement of the strength and endurance of the paralyzed lower leg muscles, and in an increased ROM of the ankle joints. Video game-based training programs might be effective in motivating participants to train more frequently and adhere to otherwise tedious training protocols. It is expected that such training will not only improve the properties of their muscles but also decrease the severity and frequency of secondary complications that result from SCI.

Gait training regimen for incomplete spinal cord injury using functional electrical stimulation.

STUDY DESIGN: Case series, and repeated assessments of the same individuals. OBJECTIVE: To demonstrate the feasibility and efficacy of a multiweek intervention on walking function in people with chronic, incomplete spinal cord injuries. SETTING: Rehabilitation hospital for spinal cord injury (SCI) in Toronto, Canada. METHODS: A convenience sample of five subjects with chronic, incomplete SCI trained for 12-18 weeks using a new multichannel neuroprosthesis for walking. The following outcome measures were recorded throughout the training period: walking speed, step frequency and average stride length based on a 2-min walk test. Also identified were which walking aids and orthoses subjects preferred to use, and whether they employed a step-to or step-through gait strategy. Follow-up measurements of three subjects were made up to 10 weeks after treatment. RESULTS: All subjects demonstrated significant improvements in walking function over the training period. Four of the subjects achieved significantly increased walking speeds, which were due to increases in both stride length and step frequency. The fifth subject experienced a significant reduction in preferred assistive devices. Follow-up measurements revealed that two subjects walked slightly slower several weeks after treatment, but they still walked significantly faster than at the start of treatment. CONCLUSION: The gait training regimen was effective for improving voluntary walking function in a population for whom significant functional changes are not expected. This application of functional electrical therapy is viable for rehabilitation of gait in incomplete SCI.

Functional electrical therapy: retraining grasping in spinal cord injury.

OBJECTIVE: To determine the clinical efficacy of functional electrical therapy in the rehabilitation of grasping function for quadriplegics. STUDY DESIGN: Randomized intervention-versus-control trial. SETTING: Rehabilitation hospital for spinal cord injury in Toronto, Canada. METHODS: A total of 21 people with new spinal cord injuries ranging from C3 to C7 were randomly assigned to two groups: Control (N=9) and Intervention (N=12). The intervention was functional electrical therapy, which consisted of repetitive grasping exercises using a neuroprosthesis that applied surface electrical stimulation to the arm to generate and/or assist grasping movements. It was applied by registered Occupational Therapists in a clinical setting. Main outcome measures were: Functional Independence Measure (FIM), Spinal Cord Independence Measure (SCIM), and the Rehabilitation Engineering Laboratory Hand Function Test. Consumer perceptions of functional electrical therapy were assessed via qualitative interviews. RESULTS: Differences between the Control and Intervention groups could be observed although they are not significant due to an insufficient number of participants. Consumer perceptions were positive, including improved Activities of Daily Living and self-satisfaction. CONCLUSION: Functional electrical therapy has the potential to be an effective treatment modality to restore grasping function in quadriplegia. It can be implemented by occupational therapists in a clinical setting. Further research is required to establish suitable indications for participant selection. In addition, a larger number of participants is needed to demonstrate statistical significance of the Functional Electrical Therapy.

[Characteristics of surgical sutures in the duodenum and small intestine]. / Osobenosti hirurskog sava duodenuma i tankog creva.

The particularities of the surgical suture of duodenum and small intestine are exposed. According to the recent experiences from the literature, the best material for the intestinal suture is monofilamentous, with delayed resorption rate, and characterized by the hardness appropriate to the tissue involved. The representatives of these are Polyglactin and Polydioxanon. In the technique of the duodenal suture, inversion of the tissue and placing the sutures in the healthy tissue are more important than mucosal inversion and multiple layers closure. The omental patch must be variable, and not involved directly in sutures. In the small intestinal surgery, one layer sero muscular-extramucosal, or two layers mucomucosal with inversion and seroserosal suture are to be used. For duodenojejunal transition, terminolateral anastomosis is recommendable. Upon lower parts of ileum oblique terminoterminal or latero-lateral anastomosis is to be used. In the cases of luminal disproportion between open ends, terminolateral anastomosis seems to be the best choice. The percentage of duodenal stump dehiscence in the period of 1986-1992. is 2.53% upon 356 emergencies of delayed operations, and the percentage of the intestinal anastomotic dehiscence upon 102 elective and emergency operations is 5.8%.

Functional electrical stimulation for grasping and walking: indications and limitations.

This review describes the state of art in the field of Functional Electrical Stimulation (FES) and its impact on improving grasping and walking functions in acute and chronic Spinal Cord Injured (SCI) patients. It is argued that during the early rehabilitation period the FES systems with surface stimulation electrodes should be used to assist training of hand and leg movements in SCI patients. Our clinical trials have shown that a number of acute SCI patients with impaired walking and grasping functions could improve these functions due to training with an adjustable FES system to the point that they finally did not need the FES system to carry out these tasks. Other acute SCI patients, who did not recover the desired function, were enabled to perform either walking or grasping with the FES assistance. We believe that the subjects who can perform grasping or walking with the help of FES, and still use the neuroprosthesis 6 months after being subjected to the FES training, should consider the FES system as a prosthetic device in Activities of Daily Living (ADL). Despite the significant technical progress achieved in the last 10 to 15 years in the FES field, there is a general consensus that these systems are not sufficiently advanced and that they need further development. The limited acceptance of the FES technology can be in part explained by the fact that it is not completely mature and that the patients still require daily assistance to use the FES systems. Nevertheless the present FES treatments combined with conventional occupational and physical therapy still remain the most promising approach in rehabilitating SCI patients. In this review, advantages and limitations of different FES systems that are used to restore grasping and walking functions are discussed.