Corticospinal neuroprostheses to restore locomotion after spinal cord injury

In this conceptual review, we highlight our strategy for, and progress in the development of corticospinal neuroprostheses for restoring locomotor functions and promoting neural repair after thoracic spinal cord injury in experimental animal models. We specifically focus on recent developments in recording and stimulating neural interfaces, decoding algorithms, extraction of real-time feedback information, and closed-loop control systems. Each of these complex neurotechnologies plays a significant role for the design of corticospinal neuroprostheses. Even more challenging is the coordinated integration of such multifaceted technologies into effective and practical neuroprosthetic systems to improve movement execution, and augment neural plasticity after injury. In this review we address our progress in rodent animal models to explore the viability of a technology-intensive strategy for recovery and repair of the damaged nervous system. The technical, practical, and regulatory hurdles that lie ahead along the path toward clinical applications are enormous – and their resolution is uncertain at this stage. However, it is imperative that the discoveries and technological developments being made across the field of neuroprosthetics do not stay in the lab, but instead reach clinical fruition at the fastest pace possible.     

The Muscle Sensor for on-site neuroscience lectures to pave the way for a better understanding of brain–machine-interface research

Neuroscience is an expanding field of science to investigate enigmas of brain and human body function. However, the majority of the public have never had the chance to learn the basics of neuroscience and new knowledge from advanced neuroscience research through hands-on experience. Here, we report that we produced the Muscle Sensor, a simplified electromyography, to promote educational understanding in neuroscience. The Muscle Sensor can detect myoelectric potentials which are filtered and processed as 3-V pulse signals to shine a light bulb and emit beep sounds. With this educational tool, we delivered “On-Site Neuroscience Lectures” in Japanese junior-high schools to facilitate hands-on experience of neuroscientific electrophysiology and to connect their text-book knowledge to advanced neuroscience researches. On-site neuroscience lectures with the Muscle Sensor pave the way for a better understanding of the basics of neuroscience and the latest topics such as how brain–machine-interface technology could help patients with disabilities such as spinal cord injuries.     

Aromatherapy for stress reduction in healthy adults: a systematic review and meta-analysis of randomized clinical trials

The aim of this review was to systematically assess the effectiveness of aromatherapy for stress management. Seven databases were searched from their inception through April 2014. RCTs testing aromatherapy against any type of controls in healthy human person that assessed stress level and cortisol level were considered. Two reviewers independently performed the selection of the studies, data abstraction and validations. The risk of bias was assessed using Cochrane criteria. Five RCTs met our inclusion criteria, and most of them had high risk of bias. Four RCTs tested the effects of aroma inhalation compared with no treatment, no aroma, and no odour oil. The meta-analysis suggested that aroma inhalation has favourable effects on stress management (n = 80; standard mean difference (SMD), −0.96; 95% CI, −1.44 to −0.48; P < 0.0001; I² = 0%). Three of included RCTs tested aroma inhalation on saliva or serum cortisol level compared with control and meta-analysis failed to show significant difference between two groups (n = 88, SMDs −0.62; 95% CIs −1.26 to 0.02, P = 0.06, I² = 46%). In conclusion, there is limited evidence suggesting that aroma inhalation may be effective in controlling stress. However, the number, size and quality of the RCTs are too low to draw firm conclusions.     

Detection of Cryptosporidium and Giardia in clinical laboratories in Europe—a comparative study

To determine the routine diagnostic methods used and compare the performance in detection of oocysts of Cryptosporidium species and cysts of Giardia intestinalis in faecal samples by European specialist parasitology laboratories and European clinical laboratories. Two sets of seven formalin-preserved faecal samples, one containing cysts of Giardia intestinalis and the other, containing oocysts of Cryptosporidium, were sent to 18 laboratories. Participants were asked to examine the specimens using their routine protocol for detecting these parasites and state the method(s) used. Eighteen laboratories answered the questionnaire. For detection of Giardia, 16 of them used sedimentation/concentration followed by light microscopy. Using this technique the lower limit of detection of Giardia was 17.2 cysts/mL of faeces in the best performing laboratories. Only three of 16 laboratories used fluorescent-conjugated antibody-based microscopy. For detection of Cryptosporidium acid-fast staining was used by 14 of the 17 laboratories that examined the samples. With this technique the lower limit of detection was 976 oocysts/mL of faeces. Fluorescent-conjugated antibody-based microscopy was used by only five of the 17 laboratories. There was variation in the lower limit of detection of cysts of Giardia and oocysts of Cryptosporidium between laboratories using the same basic microscopic methods. Fluorescent-conjugated antibody-based microscopy was not superior to light microscopy under the conditions of this study. There is a need for a larger-scale multi-site comparison of the methods used for the diagnosis of these parasites and the development of a Europe-wide laboratory protocol based upon its findings.     

Femoral loosening of high-flexion total knee arthroplasty: The effect of posterior cruciate ligament retention and bone quality reduction

High-flexion total knee arthroplasty (TKA) may be more sensitive to femoral loosening than conventional TKA as the knee joint force increases during deep flexion. The objective of this study was to evaluate whether the probability of femoral loosening is equal in posterior cruciate ligament (PCL) retaining and substituting high-flexion knee implants and whether loosening is related to femoral bone quality. A three-dimensional finite element (FE) model of the knee was developed and a weight-bearing deep knee bend up to 155° was simulated. PCL conservation considerably increased the compressive tibio-femoral joint force as a maximal force of 4.7–6.0 × bodyweight (BW) was found, against a maximal force of 4.0 × BW for posterior-stabilized TKA. Roughly 14% of the fixation site beneath the anterior femoral flange was predicted to debond on the long-term in case of cruciate-retaining TKA compared to 20% in case of posterior-stabilized TKA. Reducing the femoral bone quality to 50% of its original bone mineral density increased the amount of potential anterior failure for cruciate-retaining TKA to 22% and posterior-stabilized TKA to 24%. We therefore conclude that the femoral fixation site has a similar failure potential for both cruciate-retaining and posterior-stabilized high-flexion TKA.     

Automatic detection of wakefulness and rest intervals in actigraphic signals: A data-driven approach

Actigraphy is an useful tool for evaluating the activity pattern of a subject; activity registries are usually processed by first splitting the signal into its wakefulness and rest intervals and then analyzing each one in isolation. Consequently, a preprocessing stage for such a splitting is needed. Several methods have been reported to this end but they rely on parameters and thresholds which are manually set based on previous knowledge of the signals or learned from training. This compromises the general applicability of this methods. In this paper we propose a new method in which thresholds are automatically set based solely on the specific registry to be analyzed. The method consists of two stages: (1) estimation of an initial classification mask by means of the expectation maximization algorithm and (2) estimation of a final refined mask through an iterative method which re-estimates both the mask and the classifier parameters at each iteration step. Results on real data show that our methodology outperforms those so far proposed and can be more effectively used to obtain derived sleep quality parameters from actigraphy registries.     

Design parameters and the material coupling are decisive for the micromotion magnitude at the stem–neck interface of bi-modular hip implants

Several bi-modular hip prostheses exhibit an elevated number of fretting-related postoperative complications most probably caused by excessive micromotions at taper connections. This study investigated micromotions at the stem–neck interface of two different designs: one design (Metha, Aesculap AG) has demonstrated a substantial number of in vivo neck fractures for Ti–Ti couplings, but there are no documented fractures for Ti–CoCr couplings. Conversely, for a comparable design (H-Max M, Limacorporate) with a Ti–Ti coupling only one clinical failure has been reported. Prostheses were mechanically tested and the micromotions were recorded using a contactless measurement system.For Ti–Ti couplings, the Metha prosthesis showed a trend towards higher micromotions compared to the H-Max M (6.5 ± 1.6 μm vs. 3.6 ± 1.5 μm, p = 0.08). Independent of the design, prostheses with Ti neck adapter caused significantly higher interface micromotions than those with CoCr ones (5.1 ± 2.1 μm vs. 0.8 ± 1.6 μm, p = 0.001). No differences in micromotions between the Metha prosthesis with CoCr neck and the H-Max M with Ti neck were observed (2.6 ± 2.0 μm, p = 0.25).The material coupling and the design are both crucial for the micromotions magnitude. The extent of micromotions seems to correspond to the number of clinically observed fractures and confirm the relationship between those and the occurrence of fretting corrosion.     

A model to predict deflection of bevel-tipped active needle advancing in soft tissue

Active needles are recently being developed to improve steerability and placement accuracy for various medical applications. These active needles can bend during insertion by actuators attached to their bodies. The bending of active needles enables them to be steered away from the critical organs on the way to target and accurately reach target locations previously unachievable with conventional rigid needles. These active needles combined with an asymmetric bevel-tip can further improve their steerability. To optimize the design and to develop accurate path planning and control algorithms, there is a need to develop a tissue–needle interaction model. This work presents an energy-based model that predicts needle deflection of active bevel-tipped needles when inserted into the tissue. This current model was based on an existing energy-based model for bevel-tipped needles, to which work of actuation was included in calculating the system energy. The developed model was validated with needle insertion experiments with a phantom material. The model predicts needle deflection reasonably for higher diameter needles (11.6% error), whereas largest error was observed for the smallest needle diameter (24.7% error).