Mechanism of nitric oxide induced sympatholysis in rat soleus feed arteries

During exercise, the neurotransmitter norepinephrine (NE) binds to arterial adrenergic receptors to cause vasoconstriction, yet arteries and arterioles constrict less to sympathetic stimulation in contracting compared to resting skeletal muscle (sympatholysis). Previous evidence indicates that nitric oxide (NO) can be sympatholytic, but the mechanism is unknown. We hypothesized that NO causes sympatholysis in rat soleus muscle feed arteries, that NO is released from vascular endothelial cells by increased shear stress, and that NO acts through a guanylyl cyclase intracellular signaling pathway. Soleus feed arteries (n = 12 per group) were isolated from male Sprague-Dawley rats and cannulated on two glass micropipettes for in vitro videomicroscopy. We measured the constriction response to the adrenergic agonist phenylephrine (PE; 10-9 M to 10-4 M, 0.5 log increments) in the presence of varying levels of the nitric oxide donor sodium nitroprusside (SNP; 0 nM, 0.1 nM and 100 nM), shear stress (0 dy/cm2, 25 dy/cm2, and 135 dy/cm2), and SNP + ODQ (0.1 nM), an inhibitor of guanylyl cyclase. SNP reduced constriction to PE in a dose-dependent manner (maximum constriction 77.3 % vs. 70.7 % and 56.7 %), indicating that NO interferes with sympathetic constriction. ODQ restored PE-induced constriction (PE alone 77.5%; with SNP 67.6%; with SNP + ODQ 83.5%), indicating that NO causes sympatholysis through a guanylyl cyclase signaling pathway. However, shear stress did not reduce constriction to PE (67.6 % vs. 68.1 %, and 67.6 %), indicating that increased shear stress during exercise is not the source of the NO causing sympatholysis. We conclude that nitric oxide acting through guanylyl cyclase causes sympatholysis, but the source of the nitric oxide during exercise is not shear stress-induced endothelial cell activation

Adapting the National Diabetes Prevention Program: Learning from Lifestyle Coach strategies and adjustments during the COVID-19 pandemic in the United States

Background: The National Diabetes Prevention Program (National DPP) is an evidence-based lifestyle intervention successfully disseminated across the United States. Some adaptations have been made to address real-world needs, including during the COVID-19 pandemic. This study aims to qualitatively describe adaptations Lifestyle Coaches made in response to the pandemic. Methods: Between May and June 2021, Lifestyle Coaches (n = 300) from organizations across the United States answered open-ended survey questions about adjustments implemented during the pandemic. Survey responses were descriptively coded and codes were grouped into categories. Results: Nearly all coaches transitioned the format of their class from in-person to remote delivery (93.0 %; n = 279). Other commonly-reported strategies included adjusting contact with participants (48.0 %; n = 144), increasing support for participants (36.7 %; n = 110), and tailoring materials (28.3 %; n = 85). Conclusions: Maintaining these adaptations may address barriers to engagement in the National DPP and improve access to the program. Increased support for emotional symptoms and ensuring a patient-centered approach to care are particularly promising strategies

User-centered development of a smartphone application (Fit2Thrive) to promote physical activity in breast cancer survivors

Increased moderate and vigorous physical activity (MVPA) is associated with better health outcomes in breast cancer survivors; yet, most are insufficiently active. Smartphone applications (apps) to promote MVPA have high scalability potential, but few evidence-based apps exist. The purpose is to describe the testing and usability of Fit2Thrive, a MVPA promotion app for breast cancer survivors. A user-centered, iterative design process was utilized on three independent groups of participants. Two groups of breast cancer survivors (group 1 n = 8; group 2: n = 14) performed app usability field testing by interacting with the app for ≥3 days in a free-living environment. App refinements occurred following each field test. The Post-Study System Usability Questionnaire (PSSUQ) and the User Version Mobile Application Rating Scale (uMARS) assessed app usability and quality on a 7- and 5-point scale, respectively, and women provided qualitative written feedback. A third group (n = 15) rated potential app notification content. Quantitative data were analyzed using descriptive statistics. Qualitative data were analyzed using a directed content analysis. The PSSUQ app usability score (M1= 3.8; SD = 1.4 vs. M2= 3.2; SD = 1.1; lower scores are better) and uMARS app quality score (M1 = 3.4; SD = 1.3 vs. M2= 3.4; SD = 0.6; higher scores are better) appeared to improve in Field Test 2. Group 1 participants identified app "clunkiness," whereas group 2 participants identified issues with error messaging/functionality. Group 3 "liked" 53% of the self-monitoring, 71% of the entry reminder, 60% of the motivational, and 70% of the goal accomplishment notifications. Breast cancer survivors indicated that the Fit2Thrive app was acceptable and participants were able to use the app. Future work will test the efficacy of this app to increase MVPA

Optimization of a technology-supported physical activity promotion intervention for breast cancer survivors: Results from Fit2Thrive

Background The benefits of moderate to vigorous physical activity (MVPA) for breast cancer survivors are well established. However, most are insufficiently active. Fit2Thrive used the Multiphase Optimization Strategy methodology to determine the effect of 5 intervention components on MVPA in this population. Methods Two hundred sixty-nine participants (mean age, 52.5 years; SD, 9.9 years) received a core intervention (the Fit2Thrive self-monitoring app and Fitbit) and were randomly assigned to 5 intervention components set to on/off in a full factorial experiment: support calls, deluxe app, buddy, online gym, and text messages. The intervention was delivered over 12 weeks with a 12-week follow-up. MVPA was measured via accelerometry at the baseline (T1), at 12 weeks (T2), and at 24 weeks (T3). The main effects and interaction effects at each time point were examined for all components. Results Trial retention was high: 91.8% had valid accelerometer data at T2 or T3. Across all conditions, there were significant increases in MVPA (+53.6 min/wk; P < .001) and in the proportion of survivors meeting MVPA guidelines (+22.3%; P < .001) at T2 that were maintained but attenuated at T3 (MVPA, +24.6 min/wk; P < .001; meeting guidelines, +12.6%; P < .001). No individual components significantly improved MVPA, although increases were greater for the on level versus the off level for support calls, buddy, and text messages at T2 and T3. Conclusions The Fit2Thrive core intervention (the self-monitoring app and Fitbit) is promising for increasing MVPA in breast cancer survivors, but the components provided no additional increases in MVPA. Future research should evaluate the core intervention in a randomized trial and determine what components optimize MVPA behaviors in breast cancer survivors