Reducing Motor Variability Enhances Myoelectric Control Robustness Across Untrained Limb Positions

The limb position effect is a multi-faceted problem, associated with decreased upper-limb prosthesis control acuity following a change in arm position. Factors contributing to this problem can arise from distinct environmental or physiological sources. Despite their differences in origin, the effect of each factor manifests similarly as increased input data variability. This variability can cause incorrect decoding of user intent. Previous research has attempted to address this by better capturing input data variability with data abundance. In this paper, we take an alternative approach and investigate the effect of reducing trial-to-trial variability by improving the consistency of muscle activity through user training. Ten participants underwent 4 days of myoelectric training with either concurrent or delayed feedback in a single arm position. At the end of training participants experienced a zero-feedback retention test in multiple limb positions. In doing so, we tested how well the skill learned in a single limb position generalized to untrained positions. We found that delayed feedback training led to more consistent muscle activity across both the trained and untrained limb positions. Analysis of patterns of activations in the delayed feedback group suggest a structured change in muscle activity occurs across arm positions. Our results demonstrate that myoelectric user-training can lead to the retention of motor skills that bring about more robust decoding across untrained limb positions. This work highlights the importance of reducing motor variability with practice, prior to examining the underlying structure of muscle changes associated with limb position.

Evidencing the effectiveness of upper limb prostheses: a multi-stakeholder perspective on study requirements

The provision of upper limb prosthetic devices through the National Health Services (NHS) within the United Kingdom is driven by national policies. NHS England have recently published a new policy to provide multi-grip myoelectric hands. The policy highlighted that there was limited evidence to support its deployment and it will be reviewed should new information arise. The clear identification of the evidence gap provides an opportunity for the academic research community to conduct studies that will inform future iterations of this and other upper limb prosthetic related policies. This paper presents a summary of findings and recommendations based on two multi-stakeholder workshops held in June 2022 and July 2022, which explored the design requirements for policy-driven research studies. The workshops involved people from a broad range of stakeholder groups: policy, academia, NHS clinical and management, industry, and a person with upper limb absence. The workshop discussions focused on the research questions that NHS England identified in the policy evidence review: (1) Clinical Effectiveness; (2) Cost Effectiveness; (3) Safety; and (4) Patient Subgroups. The recommendations based on stakeholder discussions included the need to gather qualitative and quantitative research evidence, use goal-based outcome measures, and conduct longitudinal studies. Future research studies also need to address the complexities of conducting national and international policy-driven research, such as clinical resource capacity and participant involvement.

Delaying feedback during pre-device training facilitates the retention of novel myoelectric skills: a laboratory and home-based study

OBJECTIVE

The objective of this study was to assess the impact of delayed feedback training on the retention of novel myoelectric skills, and to demonstrate the use of this training approach in the home environment.

APPROACH

We trained limb-intact participants to use a motor learning-based upper-limb prosthesis control scheme called abstract decoding. A delayed feedback paradigm intended to prevent within-trial adaptation and to facilitate motor learning was used. We conducted two multi-day experiments. Experiment 1 was a laboratory-based study consisting of two groups trained over a four-day period with concurrent or delayed feedback. An additional follow-up session took place after 18 days to assess the retention of motor skills. Experiment 2 was a home-based pilot study that took place over five consecutive days to investigate delayed feedback performance when using bespoke training structures.

MAIN RESULTS

Approximately 35,000 trials were collected across both experiments. Experiment 1 found that the retention of motor skills for the delayed feedback group was significantly better than that of their concurrent feedback counterparts. In addition, the delayed feedback group improved their retention of motor skills across days, whereas the concurrent feedback group did not. Experiment 2 demonstrated that by using a bespoke training protocol in an environment that is more conducive to learning, it is possible for participants to become highly accurate in the absence of feedback.

SIGNIFICANCE

These results show that with delayed feedback training, it is possible to retain novel myoelectric skills. Using abstract decoding participants can activate four distinct muscle patterns without using complex algorithms. The accuracy achieved in the pilot study supports the feasibility of motor learning-based upper-limb prosthesis control after home-based myoelectric training.&#xD.

Increasing Voluntary Myoelectric Training Time Through Game Design

In virtual prosthetic training research, serious games have been investigated for over 30 years. However, few game design elements are used and assessed for their effect on the voluntary adherence and repetition of the performed task. We compared two game-based versions of an established myoelectric-controlled virtual prosthetic training task with an interface without game elements of the same task [for video, see (Garske, 2022)]. Twelve limb-intact participants were sorted into three groups of comparable ability and asked to perform the task as long as they were motivated. Following the task, they completed a questionnaire regarding their motivation and engagement in the task. The investigation established that participants in the game-based groups performed the task significantly longer when more game design elements were implemented in the task (medians of 6 vs. 9.5 vs. 14 blocks for groups with increasing number of different game design elements). The participants in the game-based versions were also more likely to end the task out of fatigue than for reasons of boredom or frustration, which was verified by a fatigue analysis of the myoelectric signal. We demonstrated that the utilization of game design methodically in virtual myoelectric training tasks can support adherence and duration of a virtual training, in the short-term. Whether such short-term enhanced engagement would lead to long-term adherence remains an open question.

Internet of Things for beyond-the-laboratory prosthetics research

Research on upper-limb prostheses is typically laboratory-based. Evidence indicates that research has not yet led to prostheses that meet user needs. Inefficient communication loops between users, clinicians and manufacturers limit the amount of quantitative and qualitative data that researchers can use in refining their innovations. This paper offers a first demonstration of an alternative paradigm by which remote, beyond-the-laboratory prosthesis research according to user needs is feasible. Specifically, the proposed Internet of Things setting allows remote data collection, real-time visualization and prosthesis reprogramming through Wi-Fi and a commercial cloud portal. Via a dashboard, the user can adjust the configuration of the device and append contextual information to the prosthetic data. We evaluated this demonstrator in real-time experiments with three able-bodied participants. Results promise the potential of contextual data collection and system update through the internet, which may provide real-life data for algorithm training and reduce the complexity of send-home trials. This article is part of the theme issue 'Advanced neurotechnologies: translating innovation for health and well-being'.

Does Trans-radial Longitudinal Compression Influence Myoelectric Control?

BACKGROUND

Existing trans-radial prosthetic socket designs are not optimised to facilitate reliable myoelectric control. Many socket designs pre-date the introduction of myoelectric devices. However, socket designs featuring improved biomechanical stability, notably longitudinal compression sockets, have emerged in more recent years. Neither the subsequent effects, if any, of stabilising the limb on myoelectric control nor in which arrangement to apply the compression have been reported.

METHODOLOGY

Twelve able-bodied participants completed two tasks whilst wearing a longitudinal compression socket simulator in three different configurations: 1) compressed, where the compression strut was placed on top of the muscle of interest, 2) relief, where the compression struts were placed either side of the muscle being recorded and 3) uncompressed, with no external compression. The tasks were 1) a single-channel myoelectric target tracking exercise, followed by 2), a high-intensity grasping task. The wearers' accuracy during the tracking task, the pressure at opposing sides of the simulator during contractions and the rate at which the limb fatigued were observed.

FINDINGS

No significant difference between the tracking-task accuracy scores or rate of fatigue was observed for the different compression configurations. Pressure recordings from the compressed configuration showed that pressure was maintained at opposing sides of the simulator during muscle contractions.

CONCLUSION

Longitudinal compression does not inhibit single-channel EMG control, nor improve fatigue performance. Longitudinal compression sockets have the potential to improve the reliability of multi-channel EMG control due to the maintenance of pressure during muscle contractions.

Towards User-Centred Prosthetics Research Beyond the Laboratory

The purpose of this study was to explore a range of perspectives on how academic research and clinical assessment of upper-limb prosthetics could happen in environments outside of laboratories and clinics, such as within peoples' homes. Two co-creation workshops were held, which included people who use upper limb prosthetic devices (hereafter called users), clinicians, academics, a policy stakeholder, and a representative from the upper-limb prosthetics industry (hereafter called professionals). The discussions during the workshops indicate that research and clinical assessment conducted remotely from a laboratory or clinic could inform future solutions that address user needs. Users were open to the idea of sharing sensor and contextual data from within their homes to external laboratories during research studies. However, this was dependent upon several considerations, such as choice and control over data collection. Regarding clinical assessment, users had reservations of how data may be used to inform future prosthetic prescriptions whilst, clinicians were concerned with resource implications and capacity to process user data. The paper presents findings of the discussions shared by participants during both workshops. The paper concludes with a conjecture that collecting sensor and contextual data from users within their home environment will contribute towards literature within the field, and potentially inform future care policies for upper limb prosthetics. The involvement of users during such studies will be critical and can be enabled via a co-creation approach. In the short term, this may be achieved through academic research studies, which may in the long term inform a framework for clinical in-home trials and clinical remote assessment.

Serious Games Are Not Serious Enough for Myoelectric Prosthetics

Serious games show a lot of potential for use in movement rehabilitation (eg, after a stroke, injury to the spinal cord, or limb loss). However, the nature of this research leads to diversity both in the background of the researchers and in the approaches of their investigation. Our close examination and categorization of virtual training software for upper limb prosthetic rehabilitation found that researchers typically followed one of two broad approaches: (1) focusing on the game design aspects to increase engagement and muscle training and (2) concentrating on an accurate representation of prosthetic training tasks, to induce task-specific skill transfer. Previous studies indicate muscle training alone does not lead to improved prosthetic control without a transfer-enabling task structure. However, the literature shows a recent surge in the number of game-based prosthetic training tools, which focus on engagement without heeding the importance of skill transfer. This influx appears to have been strongly influenced by the availability of both software and hardware, specifically the launch of a commercially available acquisition device and freely available high-profile game development engines. In this Viewpoint, we share our perspective on the current trends and progress of serious games for prosthetic training.

Remote creation of clinical-standard myoelectric trans-radial bypass sockets during COVID-19

To enable the progression of research during the COVID-19 lockdown, a novel remote method of creating clinical standard trans-radial bypass sockets was devised as a collaboration between an engineering team and a clinical research group. The engineering team recruited two able-bodied participants, marked areas of interest on the participant's limb and captured limb geometry and electrode sites with a high definition optical scanner. The resulting 3D scan was modified to make electrode sites and areas of interest recessed and tactile. Models were 3D printed to scale and posted to the clinical team to manufacture the sockets. A modified lamination process was used, comprising plaster casting and rectifiying the model by hand. The recessed areas of the 3D printed model were used to guide the process. The bypass sockets were returned to the engineering team for testing. A simple electromyography (EMG) tracking task was performed using clinical electrodes to validate the skin-electrode contact and alignment. This paper demonstrates a validated method for remotely creating transradial bypass sockets. There is potential to extrapolate this method to standard socket fittings with further research.

Long-Term Myoelectric Training with Delayed Feedback in the Home Environment

Myoelectric prosthesis users typically do not receive immediate feedback from their device. They must be able to consistently produce distinct muscle activations in the absence of augmented feedback. In previous experiments, abstract decoding has provided real-time visual feedback for closed loop control. It is unclear if the performance in those experiments was due to short-term adaptation or motor learning. To test if similar performance could be reached without short-term adaptation, we trained participants with a delayed feedback paradigm. Feedback was delayed until after the ~1.5 s trial was completed. Three participants trained for five days in their home environments, completing a cumulative total of 4920 trials. Participants became highly accurate while receiving no real-time feedback of their control input. They were also able to retain performance gains across days. This strongly suggests that abstract decoding with delayed feedback facilitates motor learning, enabling four class control without immediate feedback.

A Network-Enabled Myoelectric Platform for Prototyping Research Outside of the Lab

We present a network-enabled myoelectric platform for performing research outside of the laboratory environment. A low-cost, flexible, modular design based on common Internet of Things connectivity technology allows home-based research to be piloted. An outline of the platform is presented followed by technical results obtained from ten days of home-based tests with three participants. Results show the system enabled collection of close to 12,000 trials during around 28 cumulative hours of use. Home-based testing of multiple participants in parallel offers efficiency gains and provides a intuitive route toward long-term testing of upper-limb prosthetic devices in more naturalistic settings.Clinical relevance- In-home myoelectric training reduces clinician time. Network-enabled systems with back-end dashboards allow clinicians to monitor patients myoelectric ability over time and will provide a new way of accessing information about how upper-limb prosthetics are commonly used.

Co-creation and User Perspectives for Upper Limb Prosthetics

People who either use an upper limb prosthesis and/or have used services provided by a prosthetic rehabilitation centre, experience limitations of currently available prosthetic devices. Collaboration between academia and a broad range of stakeholders, can lead to the development of solutions that address peoples' needs. By doing so, the rate of prosthetic device abandonment can decrease. Co-creation is an approach that can enable collaboration of this nature to occur throughout the research process. We present findings of a co-creation project that gained user perspectives from a user survey, and a subsequent workshop involving: people who use an upper limb prosthesis and/or have experienced care services (users), academics, industry experts, charity executives, and clinicians. The survey invited users to prioritise six themes, which academia, clinicians, and industry should focus on over the next decade. The prioritisation of the themes concluded in the following order, with the first as the most important: function, psychology, aesthetics, clinical service, collaboration, and media. Within five multi-stakeholder groups, the workshop participants discussed challenges and collaborative opportunities for each theme. Workshop groups prioritised the themes based on their discussions, to highlight opportunities for further development. Two groups chose function, one group chose clinical service, one group chose collaboration, and another group chose media. The identified opportunities are presented within the context of the prioritised themes, including the importance of transparent information flow between all stakeholders; user involvement throughout research studies; and routes to informing healthcare policy through collaboration. As the field of upper limb prosthetics moves toward in-home research, we present co-creation as an approach that can facilitate user involvement throughout the duration of such studies.

3D-Printing and Upper-Limb Prosthetic Sockets: Promises and Pitfalls

Modernising the way upper-limb prosthetic sockets are made has seen limited progress. The casting techniques that are employed in clinics today resemble those developed over 50 years ago and there is still a heavy reliance on manual labour. Modern manufacturing methods such as 3D scanning and printing are often presented as ready-to-use solutions for producing low-cost functional devices, with public perceptions being largely shaped by the superficial media representation and advertising. The promise is that modern socket manufacturing methods can improve patient satisfaction, decrease manufacturing times and reduce the workload in the clinic. However, the perception in the clinical community is that total conversion to digital methods in a clinical environment is not straightforward. Anecdotally, there is currently a disconnect between those developing technology to produce prosthetic devices and the actual needs of clinicians and people with limb difference. In this paper, we demonstrate strengths and drawbacks of a fully digitised, low-cost trans-radial diagnostic socket making process, informed by clinical principles. We present volunteer feedback on the digitally created sockets and provide expert commentary on the use of digital tools in upper-limb socket manufacturing. We show that it is possible to utilise 3D scanning and printing, but only if the process is informed by expert knowledge. We bring examples to demonstrate how and why the process may go wrong. Finally, we provide discussion on why progress in modernising the manufacturing of upper-limb sockets has been slow yet it is still too early to rule out digital methods.

Perception of Game-Based Rehabilitation in Upper Limb Prosthetic Training: Survey of Users and Researchers

Background

Serious games have been investigated for their use in multiple forms of rehabilitation for decades. The rising trend to use games for physical fitness in more recent years has also provided more options and garnered more interest for their use in physical rehabilitation and motor learning. In this study, we report the results of an opinion survey of serious games in upper limb prosthetic training.

Objective

This study investigates and contrasts the expectations and preferences for game-based prosthetic rehabilitation of people with limb difference and researchers.

Methods

Both participant groups answered open and closed questions as well as a questionnaire to assess their user types. The distribution of the user types was compared with a Pearson chi-square test against a sample population. The data were analyzed using the thematic framework method; answers fell within the themes of usability, training, and game design. Researchers shared their views on current challenges and what could be done to tackle these.

Results

A total of 14 people with limb difference and 12 researchers participated in this survey. The open questions resulted in an overview of the different views on prosthetic training games between the groups. The user types of people with limb difference and researchers were both significantly different from the sample population, with χ²₅=12.3 and χ²₅=26.5, respectively.

Conclusions

We found that the respondents not only showed a general willingness and tentative optimism toward the topic but also acknowledged hurdles limiting the adoption of these games by both clinics and users. The results indicate a noteworthy difference between researchers and people with limb difference in their game preferences, which could lead to design choices that do not represent the target audience. Furthermore, focus on long-term in-home experiments is expected to shed more light on the validity of games in upper limb prosthetic rehabilitation.

Arduino-Based Myoelectric Control: Towards Longitudinal Study of Prosthesis Use

Understanding how upper-limb prostheses are used in daily life helps to improve the design and robustness of prosthesis control algorithms and prosthetic components. However, only a very small fraction of published research includes prosthesis use in community settings. The cost, limited battery life, and poor generalisation may be the main reasons limiting the implementation of home-based applications. In this work, we introduce the design of a cost-effective Arduino-based myoelectric control system with wearable electromyogram (EMG) sensors. The design considerations focused on home studies, so the robustness, user-friendly control adjustments, and user supports were the main concerns. Three control algorithms, namely, direct control, abstract control, and linear discriminant analysis (LDA) classification, were implemented in the system. In this paper, we will share our design principles and report the robustness of the system in continuous operation in the laboratory. In addition, we will show a first real-time implementation of the abstract decoder for prosthesis control with an able-bodied participant.

Automatic Myoelectric Control Site Detection Using Candid Covariance-Free Incremental Principal Component Analysis

The unknown composition of residual muscles surrounding the stump of an amputee makes optimal electrode placement challenging. This often causes the experimental set-up and calibration of upper-limb prostheses to be time consuming. In this work, we propose the use of existing dimensionality reduction techniques, typically used for muscle synergy analysis, to provide meaningful real-time functional information of the residual muscles during the calibration period. Two variations of principal component analysis (PCA) were applied to electromyography (EMG) data collected during a myoelectric task. Candid covariance-free incremental PCA (CCIPCA) detected task-specific muscle synergies with high accuracy using minimal amounts of data. Our findings offer a real-time solution towards optimizing calibration periods.

The Effect of Light on Tissue Repair

Electrotherapeutic modalities are widely used by physiotherapists to accelerate repair and reduce pain. It is important that the underlying mechanisms and effects that they produce are fully understood, together with any underlying adverse effects which may arise from their use. Light therapy is a relatively new addition to the physiotherapy arsenal and the mechanisms of action have not yet been fully identified. There is clinical evidence suggesting that it is effective in promoting tissue repair and pain relief. This, together with some recent laboratory evidence showing light to be effective in stimulating cells that are involved in the repair process to produce wound mediators, is described. The weight of evidence suggests that, if used correctly, light therapy can induce bioeffects which are beneficial to the patient.

Data Driven Spatial Filtering Can Enhance Abstract Myoelectric Control in Amputees

Myoelectric control based on multi-sensor techniques can provide an enhanced signal to noise ratio but increases hardware cost and complexity. Sensor arrays are also attractive in a prosthetics context when exact muscle positions are unknown, such as may be the case after limb loss. We present preliminary data obtained while four amputee participants engaged in an abstract myoelectric decoding task. The decoder was controlled by muscles of the forearm or upper arm depending on the level of limb loss. We compare performance using a pair of surface electromyography sensors and while using a data driven weighting of eight sensors. Performance rates demonstrate that amputee participants are able to learn the myoelectric task. Results trend strongly toward enhanced performance when using multiple spatially weighted sensors. Further studies are required to test whether the use of additional myoelectric sensing hardware in abstract decoding would lead to effective prosthesis control.

Carborane-Induced Excimer Emission of Severely Twisted Bis-o-Carboranyl Chrysene

The synthesis of a highly twisted chrysene derivative incorporating two electron deficient o-carboranyl groups is reported. The molecule exhibits a complex, excitation-dependent photoluminescence, including aggregation-induced emission (AIE) with good quantum efficiency and an exceptionally long singlet excited state lifetime. Through a combination of detailed optical studies and theoretical calculations, the excited state species are identified, including an unusual excimer induced by the presence of o-carborane. This is the first time that o-carborane has been shown to induce excimer formation ab initio, as well as the first observation of excimer emission by a chrysene-based small molecule in solution. Bis-o-carboranyl chrysene is thus an initial member of a new family of o-carboranyl phenacenes exhibiting a novel architecture for highly-efficient multi-luminescent fluorophores.

Abstract Decoding using Bayesian Muscle Activation Estimators

Two recursive Bayesian muscle activation estimators were compared against standard linear filtering during use of a myoelectric abstract decoder. The decoder was controlled by intrinsic muscles of the hand. In both experiments the linear filter outperformed the Bayesian methods in terms of general score. The Bayesian muscle decoders were faster to respond to changes in muscle activity and show promise for significantly enhancing overall decoder communication rate.

Myoelectric control with abstract decoders

OBJECTIVE

The objective of this study was to compare the use of muscles appropriate for partial-hand prostheses with those typically used for complete hand devices and to determine whether differences in their underlying neural substrates translate to different levels of myoelectric control.

APPROACH

We developed a novel abstract myoelectric decoder based on motor learning. Three muscle pairs, namely, an intrinsic and independent, an intrinsic and synergist and finally, an extrinsic and antagonist, were tested during abstract myoelectric control. Feedback conditions probed the roles of feed-forward and feedback mechanisms.

RESULTS

Both performance levels and rates of improvement were significantly higher for intrinsic hand muscles relative to muscles of the forearm. Intrinsic hand muscles showed considerable improvement generalising to decoder use without visual feedback. Results indicate that visual feedback from the decoder is used for transitioning between muscle activity levels, but not for maintaining state. Both individual and group performance were found to be strongly related to motor variability.

SIGNIFICANCE

Physiological differences inherent to the hand muscles can translate to improved prosthesis control. Our results support the use of motor learning based techniques for upper-limb myoelectric control and strongly argues for their utility in control of partial-hand prostheses. We provide evidence of myoelectric control skill acquisition and offer a formal definition for abstract decoding in the context of prosthetic control.

Controlling Molecular Conformation for Highly Efficient and Stable Deep-Blue Copolymer Light-Emitting Diodes

We report a novel approach to achieve deep-blue, high-efficiency, and long-lived solution-processed polymer light-emitting diodes (PLEDs) via a simple molecular level conformation change of an emissive conjugated polymer. We introduce rigid β-phase segments into a 95% fluorene-5% arylamine copolymer emissive layer. The arylamine moieties at low density act as efficient exciton formation sites in PLEDs, whereas the conformational change alters the nature of the dominant luminescence from a broad, charge transfer like emission to a significantly blue-shifted and highly vibronically structured excitonic emission. As a consequence, we observe a significant improvement in the Commission International de L'Eclairage ( x, y) coordinates from (0.149, 0.175) to (0.145, 0.123) while maintaining high efficiency and improved stability. We achieve a peak luminous efficiency, η = 3.60 cd/A, and a luminous power efficiency, η_w = 2.44 lm/W, values that represent state-of-the-art performance for single copolymer deep-blue PLEDs. These values are 5-fold better than for otherwise-equivalent, β-phase poly(9,9-dioctylfluorene) PLEDs (0.70 cd/A and 0.38 lm/W). This report represents the first demonstration of the use of molecular conformation as a simple but effective method to control the optoelectronic properties of a fluorene copolymer; previous examples have been confined to homopolymers.

Altered retinoid signaling compromises decidualization in human endometriotic stromal cells

Decidualization alters multiple molecular pathways in endometrium to permit successful embryo implantation. We have reported that paracrine factors, including retinoids, secreted from progesterone-treated endometrial stromal cells, act on nearby epithelial cells to induce the estradiol metabolizing enzyme HSD17B2. This same induction is not seen in endometriotic stromal cells. We have also shown significant differences in retinoid uptake, metabolism and action in endometriotic tissue and stromal cells compared to normal endometrium. Here, we characterize retinoid signaling during decidualization in these cells. Endometrial and endometriotic cells were isolated, cultured and incubated and decidualized. Genes involved in retinoid metabolism and trafficking were examined using RT-PCR and Western blotting. Prolactin, a decidualization marker, was also examined. We found that both endometrial and endometriotic stromal cells express all intracellular proteins involved in retinoid uptake and metabolism. Decidualization significantly reduced the expression of the genes responsible for retinoid uptake and shuttling to the nucleus. However, expression of CRBP1, an intracellular carrier protein for retinol, increased, as did RBP4, a carrier protein for retinol in the blood, which can function in a paracrine manner. Secreted RBP4 was detected in the media from decidualized endometrial cells but not from endometriotic cells. We believe that retinoid trafficking in endometrial stromal cells during decidualization may shift to favor paracrine rather than intracrine signaling, which may enhance signaling to the adjacent epithelium. There is blunting of this signaling in endometriotic cells. These alterations in retinoid signaling may help explain the decidualization defects and deficient estradiol inactivation (via HSD17B2) seen in endometriosis.

Fenretinide: A Potential Treatment for Endometriosis

OBJECTIVE

Fenretinide is a synthetic retinoid analogue that promotes apoptosis but has decreased toxicity when compared to other retinoids. We have previously shown that retinoic acid (RA) production in endometriotic tissue is decreased, resulting in reduced estrogen metabolism and apoptotic resistance. We hypothesize fenretinide may induce apoptosis in endometriotic cells and tissues, thereby reducing disease burden.

MATERIALS AND METHODS

Primary endometriotic stromal cells were collected, isolated, cultured, and treated with fenretinide in doses from 0 to 20 µmol/L. Cell count, viability, and immunoblots were performed to examine apoptosis. Quantitative reverse transcription-polymerase chain reaction from endometriotic cells treated with fenretinide was used to examine expression of genes involved in RA signaling including stimulated by RA 6 (STRA6), cellular RA binding protein 2 (CRABP2), and fatty acid binding protein 5 (FABP5). Endometriotic tissue was xenografted subcutaneously into the flanks of mice which were treated with fenretinide for 2 weeks, after which the mice were killed and lesion volumes calculated. Statistical analysis was performed using t test and analysis of variance.

RESULTS

Treatment with fenretinide significantly decreased total cell count (doses 5-20 µL) and viability (doses 10-20 µmol/L). Fenretinide increased protein levels of the apoptotic marker poly (ADP ribose) polymerase (starting at 10 µmol/L) and decreased proliferation marker proliferating cell nuclear antigen (10 µmol/L, starting at 8-day treatment). Examination of genes involved in retinoid uptake and action showed that treatment induced STRA6 expression while expression of CRABP2 and FABP5 remained unchanged. Fenretinide also significantly decreased the endometriotic lesion xenograft volume.

CONCLUSIONS

Fenretinide increases STRA6 expression thereby potentially reversing the pathological loss of retinoid availability. Treatment with this compound induces apoptosis. In vivo treatments decrease lesion volume. Targeting the RA signaling pathway may be a promising novel treatment for women with endometriosis.

Online extraction and single trial analysis of regions contributing to erroneous feedback detection

Understanding how the brain processes errors is an essential and active field of neuroscience. Real time extraction and analysis of error signals provide an innovative method of assessing how individuals perceive ongoing interactions without recourse to overt behaviour. This area of research is critical in modern Brain-Computer Interface (BCI) design, but may also open fruitful perspectives in cognitive neuroscience research. In this context, we sought to determine whether we can extract discriminatory error-related activity in the source space, online, and on a trial by trial basis from electroencephalography data recorded during motor imagery. Using a data driven approach, based on interpretable inverse solution algorithms, we assessed the extent to which automatically extracted error-related activity was physiologically and functionally interpretable according to performance monitoring literature. The applicability of inverse solution based methods for automatically extracting error signals, in the presence of noise generated by motor imagery, was validated by simulation. Representative regions of interest, outlining the primary generators contributing to classification, were found to correspond closely to networks involved in error detection and performance monitoring. We observed discriminative activity in non-frontal areas, demonstrating that areas outside of the medial frontal cortex can contribute to the classification of error feedback activity.

Impaired fetoplacental angiogenesis in growth-restricted fetuses with abnormal umbilical artery doppler velocimetry is mediated by aryl hydrocarbon receptor nuclear translocator (ARNT)

CONTEXT

Fetal growth restriction with abnormal umbilical artery Doppler velocimetry (FGRadv), reflective of elevated fetoplacental vascular resistance, is associated with increased risks of fetal morbidity and mortality even in comparison to those of growth-restricted fetuses with normal placental blood flow. One major cause of this abnormally elevated fetoplacental vascular resistance is the aberrantly formed, thin, elongated villous vessels that are seen in FGRadv placentas.

OBJECTIVE

The purpose of this study was to determine the role of fetoplacental endothelial cells (ECs) in angiogenesis in normal pregnancies and in those complicated by FGRadv.

DESIGN AND PARTICIPANTS

Human placental specimens were obtained from FGRadv and gestational age-matched, appropriately grown control pregnancies for EC isolation/culture and for immunohistochemical studies. Additional mechanistic studies were performed on ECs isolated from subjects with term, uncomplicated pregnancies.

MAIN OUTCOME MEASURES

We evaluated tube formation and differential angiogenic gene expression in FGRadv and control ECs, and we used ECs from uncomplicated pregnancies to further elucidate the molecular mechanisms by which angiogenesis is impaired in FGRadv pregnancies.

RESULTS

Tube formation assays showed that FGRadv ECs demonstrate fewer branch points and total length compared with those from gestational age-matched controls, and this defect was not rescued by exposure to hypoxia. FGRadv ECs also demonstrated lower aryl hydrocarbon receptor nuclear translocator (ARNT) expression. ARNT knockdown resulted in suppression of key angiogenic genes including vascular endothelial growth factor A expression and led to deficient tube formation.

CONCLUSIONS

ARNT expression in the placental vasculature mediates key angiogenic expression and fetoplacental EC angiogenesis, and low ARNT expression in FGRadv ECs appears to be a key factor in deficient angiogenesis. This, in turn, results in malformed thin villous vessels that structurally contribute to the abnormally elevated fetoplacental vascular resistance that is associated with high morbidity and mortality in fetal growth restriction.

Fenretinide: a novel treatment for endometrial cancer

Resistance to progestin treatment is a major hurdle in the treatment of advanced and reoccurring endometrial cancer. Fenretinide is a synthetic retinoid that has been evaluated in clinical trials as a cancer therapeutic and chemo-preventive agent. Fenretinide has been established to be cytotoxic to many kinds of cancer cells. In the present study, we demonstrate that fenretinide decreased cell viability and induced apoptosis in Ishikawa cells, which are an endometrial cancer cell line, in dose dependent manner in-vitro. This effect was found to be independent of retinoic acid nuclear receptor signaling pathway. Further, we have shown that this induction of apoptosis by fenretinide may be caused by increased retinol uptake via STRA6. Silencing of STRA6 was shown to decrease apoptosis which was inhibited by knockdown of STRA6 expression in Ishikawa cells. Results of an in-vivo study demonstrated that intraperitoneal injections of fenretinide in endometrial cancer tumors (created using Ishikawa cells) in mice inhibited tumor growth effectively. Immunohistochemistry of mice tumors showed a decrease in Ki67 expression and an increase in cleaved caspase-3 staining after fenretinide treatment when compared to vehicle treated mice. Collectively, our results are the first to establish the efficacy of fenretinide as an antitumor agent for endometrial cancer both in-vitro and in-vivo, providing a valuable rationale for initiating more preclinical studies and clinical trials using fenretinide for the treatment of endometrial cancer.

Targeting EGFR and PI3K pathways in ovarian cancer

Background:

The epidermal growth factor receptor (EGFR) is expressed in ovarian cancer, but agents targeting this pathway have shown little effect as single agents. This may be due to the presence of alternative pathways, particularly activation of the PI3K/Akt/MTOR pathway.

Methods:

We have therefore examined the effect of inhibitors of this pathway (ZSTK474 and sirolimus) in combination with the EGFR inhibitors erlotinib and gefitinib in ovarian cancer primary cell cultures.

Results:

The single-agent EGFR inhibitors showed little activity, although some activity was seen with the single-agent PI3K inhibitor, ZSTK474. Combinations of ZSTK474 with EGFR inhibitors showed enhanced activity with some evidence of synergy, whereas sirolimus combinations were less active. The results were not explicable on the basis of PIK3CA mutation or amplification, or PTEN loss, although one tumour with a KRAS mutation showed resistance to EGFR inhibitors. However, there was correlation of the EGFR expression with sensitivity to EGFR and resistance to PI3K active agents, and inverse correlation in the sensitivity of individual tumours to agents active against these pathways, suggesting a mechanism of action for the combination.

Conclusion:

Phase I/II clinical trials with these agents should include further pharmacodynamic endpoints and molecular characterisation to identify patients most likely to benefit from this strategy.

An analysis of performance evaluation for motor-imagery based BCI

In recent years, numerous brain-computer interfaces (BCIs) based on motor-imagery have been proposed which incorporate features such as adaptive classification, error detection and correction, fusion with auxiliary signals and shared control capabilities. Due to the added complexity of such algorithms, the evaluation strategy and metrics used for analysis must be carefully chosen to accurately represent the performance of the BCI. In this article, metrics are reviewed and contrasted using both simulated examples and experimental data. Furthermore, a review of the recent literature is presented to determine how BCIs are evaluated, in particular, focusing on the relationship between how the data are used relative to the BCI subcomponent under investigation. From the analysis performed in this study, valuable guidelines are presented regarding the choice of metrics and evaluation strategy dependent upon any chosen BCI paradigm.

Role of stem cells in human uterine leiomyoma growth

Background

Uterine leiomyoma is the most common benign tumor in reproductive-age women. Each leiomyoma is thought to be a benign monoclonal tumor arising from a single transformed myometrial smooth muscle cell; however, it is not known what leiomyoma cell type is responsible for tumor growth. Thus, we tested the hypothesis that a distinct stem/reservoir cell-enriched population, designated as the leiomyoma-derived side population (LMSP), is responsible for cell proliferation and tumor growth.

Principal Findings

LMSP comprised approximately 1% of all leiomyoma and 2% of all myometrium-derived cells. All LMSP and leiomyoma-derived main population (LMMP) but none of the side or main population cells isolated from adjacent myometrium carried a mediator complex subunit 12 mutation, a genetic marker of neoplastic transformation. Messenger RNA levels for estrogen receptor-α, progesterone receptor and smooth muscle cell markers were barely detectable and significantly lower in the LMSP compared with the LMMP. LMSP alone did not attach or survive in monolayer culture in the presence or absence of estradiol and progestin, whereas LMMP readily grew under these conditions. LMSP did attach and survive when directly mixed with unsorted myometrial cells in monolayer culture. After resorting and reculturing, LMSP gained full potential of proliferation. Intriguingly, xenografts comprised of LMSP and unsorted myometrial smooth muscle cells grew into relatively large tumors (3.67±1.07 mm³), whereas xenografts comprised of LMMP and unsorted myometrial smooth muscle cells produced smaller tumors (0.54±0.20 mm³, p<0.05, n = 10 paired patient samples). LMSP xenografts displayed significantly higher proliferative activity compared with LMMP xenografts (p<0.05).

Conclusions

Our data suggest that LMSP, which have stem/reservoir cell characteristics, are necessary for in vivo growth of leiomyoma xenograft tumors. Lower estrogen and progesterone receptor levels in LMSP suggests an indirect paracrine effect of steroid hormones on stem cells via the mature neighboring cells.

Role of estrogen receptor-β in endometriosis

Endometriosis is an estrogen-dependent disease. The biologically active estrogen, estradiol, aggravates the pathological processes (e.g., inflammation and growth) and the symptoms (e.g., pain) associated with endometriosis. Abundant quantities of estradiol are available for endometriotic tissue via several mechanisms including local aromatase expression. The question remains, then, what mediates estradiol action. Because estrogen receptor (ER)β levels in endometriosis are >100 times higher than those in endometrial tissue, this review focuses on this nuclear receptor. Deficient methylation of the ERβ promoter results in pathological overexpression of ERβ in endometriotic stromal cells. High levels of ERβ suppress ERα expression. A severely high ERβ-to-ERα ratio in endometriotic stromal cells is associated with suppressed progesterone receptor and increased cyclo-oxygenase-2 levels contributing to progesterone resistance and inflammation. ERβ-selective estradiol antagonists may serve as novel therapeutics of endometriosis in the future.

Endometriosis expresses a molecular pattern consistent with decreased retinoid uptake, metabolism and action

BACKGROUND

Retinoic acid (RA) regulates key biological processes, including differentiation, apoptosis and cell survival. RA mediates induction of 17 beta-hydroxysteroid dehydrogenase type 2 mRNA, catalyzing the conversion of estradiol to estrone, in endometrium but not endometriosis because of a defect in endometriotic stromal cells. This defect may involve both the uptake and metabolism of RA. In this study, we analyze the expression of genes involved in RA signaling in normal endometrium and endometriosis.

METHODS

Tissue and stromal cells from ovarian endometriomas and eutopic endometrium from disease-free women were collected. Real-time reverse transcription-polymerase chain reaction was used to measure mRNA levels. Western blotting was used to evaluate protein expression.

RESULTS

We found that endometriotic tissue and stromal cells demonstrated significantly decreased mRNA expression of the major genes involved in RA signaling, including STRA6, CRBP1, ALDH1A2, CRABP2 and FABP5. We found increased levels of CYP26B1, responsible for RA metabolism. Nuclear extracts showed that RARα, RXRα and PPARβ/δ were underexpressed in both tissues and stromal cells from endometriotic tissue. Differences in protein levels were confirmed by western blotting.

CONCLUSIONS

Endometriosis is characterized by a gene expression pattern suggesting a decrease in uptake and metabolism of RA. Because RA is integral in regulating key biological processes involved in cell survival, this alteration could partially explain the resistance to apoptosis found in endometriosis.

Searching for Happiness Across Cultures

Abstract

Three experiments examined the cultural relativity of emotion recognition using the visual search task. Caucasian-English and Japanese participants were required to search for an angry or happy discrepant face target against an array of competing distractor faces. Both cultural groups performed the task with displays that consisted of Caucasian and Japanese faces in order to investigate the effects of racial congruence on emotion detection performance. Under high perceptual load conditions, both cultural groups detected the happy face more efficiently than the angry face. When perceptual load was reduced such that target detection could be achieved by feature-matching, the English group continued to show a happiness advantage in search performance that was more strongly pronounced for other race faces. Japanese participants showed search time equivalence for happy and angry targets. Experiment 3 encouraged participants to adopt a perceptual based strategy for target detection by removing the term 'emotion' from the instructions. Whilst this manipulation did not alter the happiness advantage displayed by our English group, it reinstated it for our Japanese group, who showed a detection advantage for happiness only for other race faces. The results demonstrate cultural and linguistic modifiers on the perceptual saliency of the emotional signal and provide new converging evidence from cognitive psychology for the interactionist perspective on emotional expression recognition.

Mental task classification against the idle state: a preliminary investigation

The motivation for this study was to obtain candidate electrode sites for use in online self-paced brain-computer interfaces and preliminary classification results for comparison to online tests. Six mental tasks were tested for classification against an idle state. Data representing the idle state was collected in association with active mental task data during each recording session. Features were extracted in two representations, band power and reflection coefficients. A sequential forward floating search algorithm was used to obtain prevailing electrode-feature pairs for each subject-task combination under two conditions: maximising classification accuracy and maximising mean trial accuracy. Methods used to select electrode-feature combinations are found to lead to differing electrode sites in a number of task-feature combinations. An across task prevalence towards electrodes positioned in the left frontal hemisphere is observed when maximising classification accuracy.

A 3-class asynchronous BCI controlling a simulated mobile robot

We present our design and online experiments of a 3-class asynchronous BCI controlling a simulated robot in an indoor environment. Two characteristics of our design have efficiently decreased the false positive rate during the NC (No Control) mode. First, three one-vs-rest LDA classifiers are combined to control the switching between NC and IC (In Control) mode. Second, the hierarchical structure of our controller allows the most reliable class (mental task) in a specific subject to play a dominant role in the robot control. A group of simple rules triggered by local sensor signals are designed for safety and obstacle avoidance in the NC mode. In online experiments, subjects successfully controlled the robot to circumnavigate obstacles and reach small targets in separate rooms.