Rehabilitation Research at the National Institutes of Health: Moving the Field Forward (Executive Summary)

The authors summarize the discussions and proposals from a recent NIH conference, Rehabilitation Research at NIH: Moving the Field Forward, that will help guide rehabilitation research at NIH in the near future

Approximately 53 million Americans live with a disability. For decades, the National Institutes of Health (NIH) has been conducting and supporting research to discover new ways to minimize disability and enhance the quality of life of people with disabilities. After the passage of the Americans With Disabilities Act, NIH established the National Center for Medical Rehabilitation Research, with the goal of developing and implementing a rehabilitation research agenda. Currently, 17 institutes and centers at NIH invest more than $500 million per year in rehabilitation research. Recently, the director of NIH, Francis Collins, appointed a Blue Ribbon Panel to evaluate the status of rehabilitation research across institutes and centers. As a follow-up to the work of that panel, NIH recently organized a conference, “Rehabilitation Research at NIH: Moving the Field Forward.” This report is a summary of the discussions and proposals that will help guide rehabilitation research at NIH in the near future.

Rehabilitation Research at the National Institutes of Health:: Moving the Field Forward (Executive Summary)

Approximately 53 million Americans live with a disability. For decades, the National Institutes of Health (NIH) has been conducting and supporting research to discover new ways to minimize disability and enhance the quality of life of people with disabilities. After the passage of the American With Disabilities Act, the NIH established the National Center for Medical Rehabilitation Research with the goal of developing and implementing a rehabilitation research agenda. Currently, a total of 17 institutes and centers at NIH invest more than $500 million per year in rehabilitation research. Recently, the director of NIH, Dr Francis Collins, appointed a Blue Ribbon Panel to evaluate the status of rehabilitation research across institutes and centers. As a follow-up to the work of that panel, NIH recently organized a conference under the title "Rehabilitation Research at NIH: Moving the Field Forward." This report is a summary of the discussions and proposals that will help guide rehabilitation research at NIH in the near future.This article is being published almost simultaneously in the following six journals: American Journal of Occupational Therapy, American Journal of Physical Medicine and Rehabilitation, Archives of Physical Medicine and Rehabilitation, Neurorehabilitation and Neural Repair, Physical Therapy, and Rehabilitation Psychology. Citation information is as follows: Frontera WR, Bean JF, Damiano D, et al. Am J Phys Med Rehabil. 2017;97(4):393-403.

Sensor-controlled scalp cooling to prevent chemotherapy-induced alopecia in female cancer patients

BACKGROUND

Scalp cooling has been used since the 1970s to prevent chemotherapy-induced alopecia, one of the most common and psychologically troubling side effects of chemotherapy. Currently available scalp cooling systems demonstrate varying results in terms of effectiveness and tolerability.

METHODS

For the present prospective study, 55 women receiving neoadjuvant, adjuvant, or palliative chemotherapy were enrolled. The aim was to assess the effectiveness of a sensor-controlled scalp cooling system (DigniCap: Sysmex Europe GmbH, Norderstedt, Germany) to prevent chemotherapy-induced alopecia in breast or gynecologic cancer patients receiving 1 of 7 regimens. Clinical assessments, satisfaction questionnaires, and alopecia evaluations [World Health Organization (who) grading for toxicity] were completed at baseline, at each cycle, and at completion of chemotherapy.

RESULTS

Of the 55 patients, 78% underwent scalp cooling until completion of chemotherapy. In multivariate analysis, younger women and those receiving paclitaxel weekly or paclitaxel-carboplatin experienced less alopecia. The compound successful outcome ("no head covering" plus "who grade 0/1") was observed in all patients 50 years of age and younger receiving 4 cycles of docetaxel-cyclophosphamide or 6 cycles of paclitaxel-carboplatin. Conversely, alopecia was experienced by all women receiving triplet polychemotherapy (6 cycles of docetaxel-doxorubicin-cyclophosphamide). For women receiving sequential polychemotherapy regimens (3 cycles of fluorouracil-epirubicin-cyclophosphamide followed by 3 cycles of docetaxel or 4 cycles of doxorubicin-cyclophosphamide followed by 4 cycles of docetaxel), the subgroup 50 years of age and younger experienced a 43% success rate compared with a 10% rate for the subgroup pf older women receiving the same regimens.

CONCLUSIONS

The ability of scalp cooling to prevent chemotherapy-induced alopecia varies with the chemotherapy regimen and the age of the patient. Use of a compound endpoint with subjective and objective measures provides insightful and practical information when counselling patients.

Bio-Inspired Controller on an FPGA Applied to Closed-Loop Diaphragmatic Stimulation

Cervical spinal cord injury can disrupt connections between the brain respiratory network and the respiratory muscles which can lead to partial or complete loss of ventilatory control and require ventilatory assistance. Unlike current open-loop technology, a closed-loop diaphragmatic pacing system could overcome the drawbacks of manual titration as well as respond to changing ventilation requirements. We present an original bio-inspired assistive technology for real-time ventilation assistance, implemented in a digital configurable Field Programmable Gate Array (FPGA). The bio-inspired controller, which is a spiking neural network (SNN) inspired by the medullary respiratory network, is as robust as a classic controller while having a flexible, low-power and low-cost hardware design. The system was simulated in MATLAB with FPGA-specific constraints and tested with a computational model of rat breathing; the model reproduced experimentally collected respiratory data in eupneic animals. The open-loop version of the bio-inspired controller was implemented on the FPGA. Electrical test bench characterizations confirmed the system functionality. Open and closed-loop paradigm simulations were simulated to test the FPGA system real-time behavior using the rat computational model. The closed-loop system monitors breathing and changes in respiratory demands to drive diaphragmatic stimulation. The simulated results inform future acute animal experiments and constitute the first step toward the development of a neuromorphic, adaptive, compact, low-power, implantable device. The bio-inspired hardware design optimizes the FPGA resource and time costs while harnessing the computational power of spike-based neuromorphic hardware. Its real-time feature makes it suitable for in vivo applications.

Contact system revisited: an interface between inflammation, coagulation, and innate immunity

The contact system is a plasma protease cascade initiated by factor XII (FXII) that activates the proinflammatory kallikrein-kinin system and the procoagulant intrinsic coagulation pathway. Anionic surfaces induce FXII zymogen activation to form proteolytically active FXIIa. Bacterial surfaces also have the ability to activate contact system proteins, indicating an important role for host defense using the cooperation of the inflammatory and coagulation pathways. Recent research has shown that inorganic polyphosphate found in platelets activates FXII in vivo and can induce coagulation in pathological thrombus formation. Experimental studies have shown that interference with FXII provides thromboprotection without a therapy-associated increase in bleeding, renewing interest in the FXIIa-driven intrinsic pathway of coagulation as a therapeutic target. This review summarizes how the contact system acts as the cross-road of inflammation, coagulation, and innate immunity.

Effects of spinal cord injury-induced changes in muscle activation on foot drag in a computational rat ankle model

Spinal cord injury (SCI) can lead to changes in muscle activation patterns and atrophy of affected muscles. Moderate levels of SCI are typically associated with foot drag during the swing phase of locomotion. Foot drag is often used to assess locomotor recovery, but the causes remain unclear. We hypothesized that foot drag results from inappropriate muscle coordination preventing flexion at the stance-to-swing transition. To test this hypothesis and to assess the relative contributions of neural and muscular changes on foot drag, we developed a two-dimensional, one degree of freedom ankle musculoskeletal model with gastrocnemius and tibialis anterior muscles. Anatomical data collected from sham-injured and incomplete SCI (iSCI) female Long-Evans rats as well as physiological data from the literature were used to implement an open-loop muscle dynamics model. Muscle insertion point motion was calculated with imposed ankle trajectories from kinematic analysis of treadmill walking in sham-injured and iSCI animals. Relative gastrocnemius deactivation and tibialis anterior activation onset times were varied within physiologically relevant ranges based on simplified locomotor electromyogram profiles. No-atrophy and moderate muscle atrophy as well as normal and injured muscle activation profiles were also simulated. Positive moments coinciding with the transition from stance to swing phase were defined as foot swing and negative moments as foot drag. Whereas decreases in activation delay caused by delayed gastrocnemius deactivation promote foot drag, all other changes associated with iSCI facilitate foot swing. Our results suggest that even small changes in the ability to precisely deactivate the gastrocnemius could result in foot drag after iSCI.

A functional model and simulation of spinal motor pools and intrafascicular recordings of motoneuron activity in peripheral nerve

Decoding motor intent from recorded neural signals is essential for the development of effective neural-controlled prostheses. To facilitate the development of online decoding algorithms we have developed a software platform to simulate neural motor signals recorded with peripheral nerve electrodes, such as longitudinal intrafascicular electrodes (LIFEs). The simulator uses stored motor intent signals to drive a pool of simulated motoneurons with various spike shapes, recruitment characteristics, and firing frequencies. Each electrode records a weighted sum of a subset of simulated motoneuron activity patterns. As designed, the simulator facilitates development of a suite of test scenarios that would not be possible with actual data sets because, unlike with actual recordings, in the simulator the individual contributions to the simulated composite recordings are known and can be methodically varied across a set of simulation runs. In this manner, the simulation tool is suitable for iterative development of real-time decoding algorithms prior to definitive evaluation in amputee subjects with implanted electrodes. The simulation tool was used to produce data sets that demonstrate its ability to capture some features of neural recordings that pose challenges for decoding algorithms.

A system and method to interface with multiple groups of axons in several fascicles of peripheral nerves

BACKGROUND

Several neural interface technologies that stimulate and/or record from groups of axons have been developed. The longitudinal intrafascicular electrode (LIFE) is a fine wire that can provide access to a discrete population of axons within a peripheral nerve fascicle. Some applications require, or would benefit greatly from, technology that could provide access to multiple discrete sites in several fascicles.

NEW METHOD

The distributed intrafascicular multi-electrode (DIME) lead was developed to deploy multiple LIFEs to several fascicles. It consists of several (e.g. six) LIFEs that are coiled and placed in a sheath for strength and durability, with a portion left uncoiled to allow insertion at distinct sites. We have also developed a multi-lead multi-electrode (MLME) management system that includes a set of sheaths and procedures for fabrication and deployment.

RESULTS

A prototype with 3 DIME leads was fabricated and tested in a procedure in a cadaver arm. The leads were successfully routed through skin and connective tissue and the deployment procedures were utilized to insert the LIFEs into fascicles of two nerves.

COMPARISON WITH EXISTING METHOD(S)

Most multi-electrode systems use a single-lead, multi-electrode design. For some applications, this design may be limited by the bulk of the multi-contact array and/or by the spatial distribution of the electrodes.

CONCLUSION

We have designed a system that can be used to access multiple sets of discrete groups of fibers that are spatially distributed in one or more fascicles of peripheral nerves. This system may be useful for neural-enabled prostheses or other applications.

TK inhibitor treatment disrupts growth hormone axis: clinical observations in children with CML and experimental data from a juvenile animal model

BACKGROUND

Long-term treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKIs) exerts off-target effects on bone growth by either impaired growth hormone (GH) action or osseous modelling impairment.

METHODS

Body height and the GH-related parameters insulin-like growth factor 1 (IGF-1) and insulin-like growth factor-binding protein 3(IGFBP-3) were determined repetitively 3-monthly over 2 years in 21 pediatric CML-patients on standardized imatinib treatment. In an animal model 4-week-old male Wistar rats were exposed over 10 weeks to imatinib, dasatinib, or bosutinib at varying concentrations via the drinking water. Blood was collected at prepubertal age, pubertal age, and at adult age, respectively, and animals' serum levels of IGFBP-3 were measured.

RESULTS

Independent from treatment duration patients exhibited IGF-1 and IGFBP-3 levels almost exclusively in the very low range when compared to age-matched references. No clear pattern of rising or falling IGF-1 and IGFBP-3 levels was observed. In rats, compared to controls, serum IGFBP-3 was significantly lowered for all TKIs tested, at all concentrations applied, and at all ages under investigation.

CONCLUSION

Besides direct off-target effects on the growing skeleton, TKI treatment also results in lowered blood levels of IGF-1 and IGFBP-3.A juvenile rat model predicts this side effect for dasatinib and bosutinib. Thus, growth and GH- related parameters should be monitored regularly in pediatric patients with CML on TKIs.