The combined action of a passive exoskeleton and an EMG-controlled neuroprosthesis for upper limb stroke rehabilitation: First results of the RETRAINER project.

The combined use of Functional Electrical Stimulation (FES) and robotic technologies is advocated to improve rehabilitation outcomes after stroke. This work describes an arm rehabilitation system developed within the European project RETRAINER. The system consists of a passive 4-degrees-of-freedom exoskeleton equipped with springs to provide gravity compensation and electromagnetic brakes to hold target positions. FES is integrated in the system to provide additional support to the most impaired muscles. FES is triggered based on the volitional EMG signal of the same stimulated muscle; in order to encourage the active involvement of the patient the volitional EMG is also monitored throughout the task execution and based on it a happy or sad emoji is visualized at the end of each task. The control interface control of the system provides a GUI and multiple software tools to organize rehabilitation exercises and monitor rehabilitation progress. The functionality and the usability of the system was evaluated on four stroke patients. All patients were able to use the system and judged positively its wearability and the provided support. They were able to trigger the stimulation based on their residual muscle activity and provided different levels of active involvement in the exercise, in agreement with their level of impairment. A randomized controlled trial aimed at evaluating the effectiveness of the RETRAINER system to improve arm function after stroke is currently ongoing.

A patient-controlled functional electrical stimulation system for arm weight relief.

A patient-driven control strategy for Functional Electrical Stimulation (FES), which amplifies volitionally-initiated shoulder abductions, is proposed to improve stroke patients' rehabilitation. Based on the measured abduction angle, a FES-induced muscle recruitment is generated that yields a pre-specified percentage of this angle - yielding arm weight relief. To guarantee the correct recruitment also under fatigue and uncertain muscle activation we employ feedback control of the recruitment level determined by filtering the FES-evoked electromyogram. Filter parameters are user-optimized to obtain a linear relation between filter output and angle with a good signal-to-noise ratio. The auto-tuned recruitment controller (RC) was tested on five healthy subjects and compared to direct stimulation (DS) while muscle fatigue progressively occurred. Results showed a more linear relation between recruitment level and angle than between non-controlled stimulation intensity and angle (R2=0.93 vs. R2=0.79, angular range of 54°). After 6 min of stimulation, abduction decreased by 42% ± 14 for DS and by 0% ± 12 for RC, showing an effective compensation of fatigue. RC yielded significant smaller errors than DS in generating desired angles (0.23% ± 5.9 vs. 14.6% ± 9.7). When FES-induced arm weight support was provided, a mean reduction of the volitional effort (determined by Electromyography) of 78% was achieved compared to angular tracking without FES. First experiments with one acute stroke patient are also reported.

[Effect of body position on coordination of breathing and swallowing]. / Einfluss der Körperposition auf die Atem-Schluck-Koordination.

BACKGROUND: To allow passage of food, the swallowing process closes off the larynx and interrupts respiratory flow. Both the timing of the interruption of respiratory flow and the body position can affect the results of the swallowing process. OBJECTIVE: The effect of body position on the swallowing process and the coordination of breathing and swallowing is investigated. MATERIALS AND METHOD: A combined EMG/bioimpedance measurement system and a piezoelectric sensor were used to investigate coordination of breathing and swallowing of a range of food consistencies in three different body positions (90°, 45° and 0°) in healthy subjects. RESULTS: Investigations were carried out on 21 healthy subjects (12 ♂, 9 ♀). 762 swallows were recorded. Changing body position was found to have a statistically significant effect on swallow-related parameters (maximum laryngeal elevation and speed of laryngeal elevation) and breathing pattern (pre- and post-swallow breathing phases). The laryngeal elevation as well as the speed of the laryngeal elevation is influenced significantly by the consistency to be swallowed. The breathing pattern changes from saliva to solid food of inspiration/swallow/inspiration to expiration/swallow/expiration. A change of body position influences the parameters specific for swallowing and the breathing patterns significantly. CONCLUSIONS: This study demonstrates that body position affects coordination of breathing and swallowing and swallow-related parameters in healthy subjects. Our results indicate that patients should be enabled to adopt a position in which they are sitting at an angle of at least 45°.

[Electric stimulation in dysphagia therapy--a review]. / Elektrische Stimulation in der Dysphagietherapie - Eine Ubersicht.

In the last years an increased interest in the electrical stimulation has consisted in the treatment of dysphagia. In the article we introduce the anatomical and physiological premises for the method. In a critical analysis the present state of art is represented, the clinical results are checked and the chances for the future are examined.

Misregulated RNA Pol II C-terminal domain phosphorylation results in apoptosis.

Misregulation of the level of RNA polymerase II carboxyl-terminal domain (CTD) phosphatase, Fcp1, in Drosophila results in high level of caspase-mediated apoptosis. Apoptosis induction by Fcp1 misregulation requires the presence of Drosophila melanogaster (Dm)p53, but occurs without the transcriptional activation of Dmp53 proapoptotic targets rpr, ark, and hid. Overproduction of a transcription activation-defective mutant Dmp53 protein increases, while Dmp53 null background decreases significantly the level of apoptosis in Fcp1-misregulated animals. Generating the apoptotic signal does not require the function of the ATM and Rad3-related kinase (ATR), and no significant level of nucleo-cytoplasmic translocation of Dmp53 is detectable in cells expressing Fcp1 at an abnormal level. Immunostaining of larval salivary gland polytene chromosomes with anti-Dmp53 antibodies indicates Dmp53 localization at several transcriptionally active chromosomal regions in wild-type cells, while in Fcp-misregulated cells the association of Dmp53 with specific chromosomal sites is decreased.

The effect of using variable frequency trains during functional electrical stimulation cycling.

Objectives. This paper describes an experimental investigation of variable frequency stimulation patterns as a means of increasing torque production and, hence, performance in cycling induced by functional electrical stimulation. Materials and Methods. Experiments were conducted on six able-bodied subjects stimulating both quadriceps during isokinetic trials. Constant-frequency trains (CFT) with 50-msec interpulse intervals and four catchlike-inducing trains (CIT) were tested. The CITs had an initial, brief, high-frequency burst of two pulses at the onset of or within a subtetanic low-frequency stimulation train. Each stimulation train consisted of the same number of pulses. The active torques produced by each train were compared. Parametric main effect ANOVA tests were performed on the active torque-time integral (TTI), on the active torque peaks and on the time needed to reach those peaks (T2P). Results. The electrical stimulation of the quadriceps produced active torques with mean peak values in the range of 1.6-3.5 Nm and a standard error below 0.2 Nm. CITs produced a significant increase of TTI and torque peaks compared with CFTs in all the experimental conditions. In particular, during the postfatigue trials, the CITs with the doublet placed in the middle of the train produced TTIs and torque peaks about 61% and 28% larger than the CFT pattern, respectively. In addition, the CITs showed the lowest reduction of the performance between prefatigue and postfatigue conditions. Conclusions. The use of CITs improves the functional electrical stimulation cycling performance compared with CFT stimulation. This application might have a relevant clinical importance for individuals with stroke where the residual sensation is still present and thus the maximization of the performance without an excessive increase of the stimulation intensity is advisable. Therefore, exercise intensity can be increased yielding a better muscle strength and endurance that may be beneficially for later gait training in individuals with stroke.

First-aid sensor system: new methods for single-point detection and analysis of vital parameters such as pulse and respiration.

The paper describes a first aid medical sensor system that is able to detect pulse and respiration. According to an opinion poll 79% of unexperienced first aiders were looking forward to use a system that supports them in first aid situations. Such a device has to be reliable and available in everyday use (e.g. as a keychain or in a first-aid kit). Therefore we investigated a single point sensor that is able to detect both respiration and blood flow at the same point of the body, for instance on the neck. Compared to ECG-derived methods absent pulse due to pulseless electrical activity (PEA) will be recognized as such. Tests have shown that the sensor can also be used to detect deglutition and other body motion sequences.

Newly designed flow field-flow fractionation channel for macromolecules and particles in the submicrometer and micrometer range.

The flow field-flow fractionation (FIFFF) technique is a promising method for separating and analysing particles and large size macromolecules from a few nanometers to approximately 50 mum. A new fractionation channel is described featuring well defined flow conditions even for low channel heights with convenient assembling and operations features. The application of the new flow field-flow fractionation channel is proved by the analysis of pigments and other small particles of technical interest in the submicrometer range. The experimental results including multimodal size distributions are presented and discussed.

Proteasomes from Dictyostelium discoideum: characterization of structure and function.

We have isolated and purified 20 S proteasomes from Dictyostelium discoideum and characterized their proteolytic activities. Two-dimensional electrophoresis revealed 13 distinct spots. Affinity purification with a subunit-specific monoclonal antibody indicated that the preparation was homogeneous, i.e., each individual proteasome appeared to have the full set of subunits. We have not obtained any evidence for changes in subunit composition at different developmental stages. The cDNA clones coding for two subunits (4 and 5), both of the alpha-type, have been cloned and sequenced. It has been shown by immunoelectron microscopy that each proteasome is composed of two identical halves, related to each other by C2 symmetry. The resulting model implies that the alpha- and beta-subunits have a fixed pattern of relationships. D. discoideum proteasomes are found both in the cytosol and, in higher concentrations, in the nucleus.