Developing and Investigating a Nanovibration Intervention for the Prevention/Reversal of Bone Loss Following Spinal Cord Injury.

Osteoporosis disrupts the fine-tuned balance between bone formation and resorption, leading to reductions in bone quantity and quality and ultimately increasing fracture risk. Prevention and treatment of osteoporotic fractures is essential for reductions in mortality, morbidity, and the economic burden, particularly considering the aging global population. Extreme bone loss that mimics time-accelerated osteoporosis develops in the paralyzed limbs following complete spinal cord injury (SCI). In vitro nanoscale vibration (1 kHz, 30 or 90 nm amplitude) has been shown to drive differentiation of mesenchymal stem cells toward osteoblast-like phenotypes, enhancing osteogenesis and inhibiting osteoclastogenesis simultaneously. Here, we develop and characterize a wearable device designed to deliver and monitor continuous nanoamplitude vibration to the hindlimb long bones of rats with complete SCI. We investigate whether a clinically feasible dose of nanovibration (two 2 h/day, 5 days/week for 6 weeks) is effective at reversing the established SCI-induced osteoporosis. Laser interferometry and finite element analysis confirmed transmission of nanovibration into the bone, and microcomputed tomography and serum bone formation and resorption markers assessed effectiveness. The intervention did not reverse SCI-induced osteoporosis. However, serum analysis indicated an elevated concentration of the bone formation marker procollagen type 1 N-terminal propeptide (P1NP) in rats receiving 40 nm amplitude nanovibration, suggesting increased synthesis of type 1 collagen, the major organic component of bone. Therefore, enhanced doses of nanovibrational stimulus may yet prove beneficial in attenuating/reversing osteoporosis, particularly in less severe forms of osteoporosis.

The electrophysiology of aphasia: A scoping review.

OBJECTIVE: To systematically assess the body of literature using N400 and P600 as they relate to people with aphasia. The primary aim was to reveal patterns in the literature which could be used to direct future research in the development of clinically relevant Event-Related Potentials (ERPs) for language assessment, while also identifying gaps in existing knowledge and highlight areas of further inquiry. METHODS: A literature search was performed on studies published before May 2021. Relevant studies on aphasia and the two ERPs of interest were assessed for quality, and the relationship between aphasia and these ERPs was explored. RESULTS: A total of 721 articles were identified, with 30 meeting inclusion criteria. Although there is significant variation in the literature, this scoping review revealed people with aphasia show reduced amplitude, delayed latency and different distribution compared to controls, and that ERPs are modulated by severity of aphasia. CONCLUSIONS: To develop a relevant clinical tool for the management of aphasia, future research must strive to improve consistency within ERP methodology, with a greater number of diverse aphasia subtypes included in research. SIGNIFICANCE: This scoping review reveals N400 and P600 represent promising potential biomarkers for the diagnosis and ongoing management of aphasia.