Sensitivity of subcellular components of neuromuscular junctions to decreased neuromuscular activity.

Muscle unloading imparts subtotal disuse on the neuromuscular system resulting in reduced performance capacity. This loss of function, at least in part, can be attributed to disruptions at the neuromuscular junction (NMJ). However, research has failed to document morphological remodeling of the NMJ with short term muscle unloading. Here, rather than quantifying cellular components of the NMJ, we examined subcellular active zone responses to 2 weeks of unloading in male Wistar rats. It was revealed that in the plantaris, but not the soleus muscles, unloading elicited significant (P ≤ 0.05) decrements in active zone staining as measured by Bassoon, and calcium channel expression. It was also discovered that unloading decreased the area of calcium channels staining relative to active zone areas of staining suggesting potential interference in the ability of calcium influx to trigger the release of vesicles docked at the active zone. Post-synaptic adaptations of the motor endplate were not evident. This presynaptic subcellular size reduction was not associated with atrophy of the underlying plantaris muscle fibers, although atrophy of the weight-bearing soleus fibers, where no subcellular remodeling was evident, was noted. These results suggest that the active zone is highly sensitive to alterations in neuromuscular activity, and that morphological adaptation of excitatory and contractile components of the NMJ can occur independently of each other.

Preferences for Participation Measurement Among Individuals Diagnosed With Cancer: A Qualitative Content Analysis.

Individuals with cancer experience occupational participation restrictions, but there is no consensus on how to measure this construct. The objective of this study is to describe the perspectives and preferences of individuals with cancer regarding participation measurement. Forty individuals with brain, breast, colorectal, and lung cancer provided feedback on three participation measures in semi-structured interviews. Through an iterative, team-based content analysis approach, interview text was coded using the study codebook and organized into themes. Core themes included (a) participation measures highlighted occupational priorities, (b) measuring participation can identify supportive care needs, (c) measures must balance thoroughness with speed of completion, (d) measurement timeframe varies by treatment phase, and (e) evaluating community engagement is not a priority for some individuals with cancer. Integrating participation measures into cancer care can support referrals to occupational therapy and supportive services. It is essential to consider time since cancer diagnosis and client priorities when selecting participation measures.

Measuring Occupational Participation among People Diagnosed with Cancer: Interview FindingsOccupational participation focuses on an individual doing what they find important or meaningful in their daily life. Regular assessment of the occupational participation needs of people diagnosed with cancer is important, given their widespread daily life challenges. However, there is no information on preferred approaches for assessing occupational participation. We interviewed 40 people diagnosed with cancer to understand what they liked and disliked about participation surveys and the process of completing them. Key findings included that evaluating participation (a) helped participants reflect on their occupational priorities, (b) can help the medical team have a more holistic view of an individual's needs and connect people with cancer with supportive services, and (c) should be done using brief yet thorough surveys. People diagnosed with cancer recommended less focus on community engagement and more focus on mental health in surveys. Individual priorities and phase of treatment should inform occupational participation survey selection.

Perspectives of Participation in Daily Life From Cancer Survivors: A Qualitative Analysis.

Objective: To characterize how survivors of cancer define participation. Design: Cross-sectional qualitative study. Setting: Participants were enrolled from a large academic medical center in the Midwestern United States. Interviews were conducted over Zoom or phone. Participants: Survivors of cancer (N=40) with brain, breast, colorectal, or lung cancer (n=10 per group). Participants were purposively sampled to maximize variation in the study sample. Participant ages ranged from 26-83 years, with a mean age of 55 years. Seventy percent of participants were receiving active cancer treatment at the time of the interview. Interventions: Not applicable. Main Outcome Measures: Participant perspectives gathered from 1-on-1 semistructured interviews. Qualitative description and thematic analysis were used to analyze interview transcripts and develop themes from the data. Results: Survivors described participation as doing valued activities and highlighted 4 common aspects: (1) control; (2) social connection; (3) engaging in various contexts; and (4) cultivation of joy and purpose. Fully participating in life involved being able to do what they want to do without restrictions or limitations. Survivors' perspectives of control outlined how competence, choice, adaptations, and locus of control influence broader feelings of control and participation. Interviews highlighted that participation remains central to daily life among survivors of cancer. Conclusions: Rehabilitation researchers and clinicians need to establish a standard and comprehensive definition of participation. Rehabilitation providers need to consistently evaluate how participation is affected among survivors of cancer and use measures that include core aspects of participation identified in this study and previous research. Comprehensively defining participation will improve the design and selection of measurement tools and support comprehensive assessment of survivor experiences.

Juvenile Neuromuscular Systems Show Amplified Disturbance to Muscle Unloading.

Muscle unloading results in severe disturbance in neuromuscular function. During juvenile stages of natural development, the neuromuscular system experiences a high degree of plasticity in function and structure. This study aimed to determine whether muscle unloading imposed during juvenile development would elicit more severe disruption in neuromuscular function than when imposed on fully developed, mature neuromuscular systems. Twenty juvenile (3 months old) and 20 mature (8 months old) rats were equally divided into unloaded and control groups yielding a total of four groups (N = 10/each). Following the 2 week intervention period, soleus muscles were surgically extracted and using an ex vivo muscle stimulation and recording system, were examined for neuromuscular function. The unloading protocol was found to have elicited significant (P ≤ 0.05) declines in whole muscle wet weight in both juvenile and mature muscles, but of a similar degree (P = 0.286). Results also showed that juvenile muscles displayed significantly greater decay in peak force due to unloading than mature muscles, such a finding was also made for specific tension or force/muscle mass. When examining neuromuscular efficiency, i.e., function of the neuromuscular junction, it again was noted that juvenile systems were more negatively affected by muscle unloading than mature systems. These results indicate that juvenile neuromuscular systems are more sensitive to the effects of unloading than mature ones, and that the primary locus of this developmental related difference is likely the neuromuscular junction as indicated by age-related differences in neuromuscular transmission efficiency.