Developmentally distinct CD4+ Treg lineages shape the CD8+ T cell response to acute Listeria infection.

SignificanceThe CD4+ Treg response following acute Listeria infection is heterogeneous and deploys two distinct modes of suppression coinciding with initial pathogen exposure and resolution of infection. This bimodal suppression of CD8+ T cells during priming and contraction is mediated by separate Treg lineages. These findings make a significant contribution to our understanding of the functional plasticity inherent within Tregs, which allows these cells to serve as a sensitive and dynamic cellular rheostat for the immune system to prevent autoimmune pathology in the face of inflammation attendant to acute infection, enable expansion of the pathogen-specific response needed to control the infection, and reestablish immune homeostasis after the threat has been contained.

School Wellness Environments: Perceptions Versus Realities.

The U.S. Department of Agriculture Final Rule on School Wellness Policy requires schools to self-evaluate wellness policies and environments. To understand the utility of this information, this study evaluates the validity of school-reported wellness information against directly observed data. Wellness leaders at 10 Midwestern elementary schools completed a questionnaire spanning nine school wellness settings. School-reported information was compared against a direct observation protocol. Percent agreement and κ statistics were used to assess agreement between school reporters and direct observation. Overall percent agreement between reporters and direct observation was 77.1%. Agreement ranged from 67.3% (Lunchroom Environment) to 92.0% (School Wellness Policies) across the nine categories. κ results showed that 65.7% of the items demonstrated fair or better reporter agreement. The results provide preliminary support for the utility of schools' self-reported wellness information. Facilitation of independent reporting on wellness environments by school leaders will contribute to broader applications for school wellness programming.

Association Between Comprehensive School Physical Activity Program Implementation and Principal Support.

The use of Comprehensive School Physical Activity Program (CSPAP) has been recommended to help students achieve 60-minutes of physical activity each day. Implementing a CSPAP requires planning, coordination, and ongoing oversight, but an understudied factor is how principal support influences CSPAP implementation. The purpose of this study was to evaluate the impact of principal support on CSPAP implementation. Method. Schools in the Iowa FitnessGram Initiative (n = 84), a participatory network of schools committed to supporting physical education and wellness efforts, were invited to participate in the study. Physical education teachers from 42 schools completed a survey assessing CSPAP implementation and principal support for school wellness. Descriptive statistics and correlation analyses were used to report associations between the variables. A regression analysis was conducted to evaluate the impact of principal support on CSPAP implementation. Results. Almost half of the schools were reported to be fully implementing just one CSPAP component and no school was reported to be fully implementing all five. The CSPAP component with the highest reported level of implementation was quality physical education, while the lowest level of implementation was reported for family and community engagement and staff involvement. The regression analysis identified that principal support was a significant predictor of CSPAP implementation, b = 0.55, t(37) = 3.10, p < .004. Conclusions. Principal support is associated with implementation of CSPAP initiatives. Strategies that focus on how to attain principal support for CSPAP initiatives are needed and could have a significant impact on student physical activity and health.

Evaluating the implementation of the SWITCH® school wellness intervention and capacity-building process through multiple methods.

BACKGROUND: School wellness programming is important for promoting healthy lifestyles and academic achievement in youth; however, research is needed on methods that can help schools implement and sustain such programs on their own. The purpose of this study was to investigate factors within and outside the school environment that influenced school capacity for implementation and potential sustainability of wellness programming. METHODS: As part of the School Wellness Integration Targeting Child Health (SWITCH®) intervention, elementary school wellness teams (N = 30) were guided through a capacity-building process focused on promoting the adoption of healthy lifestyle behaviors in students. Data on implementation were collected through three standardized surveys and interviews (pre-mid-post) and a post-implementation interview. Indicators of organizational capacity were assessed using the School Wellness Readiness Assessment (SWRA). Paired t-tests were run to assess changes in implementation (classroom, physical education, and lunchroom settings), capacity, and stakeholder engagement over time. One-way analysis of variance (ANOVA) tests were run to examine how implementation of best practices (low, moderate, high) explained differences in capacity gains. Qualitative data were analyzed through inductive and deductive analysis, following the Consolidated Framework for Implementation Research (CFIR). RESULTS: Paired t-tests showed non-significant increases in school and setting-specific capacity and implementation of SWITCH best practices over time, in addition to a consistent level of engagement from key stakeholders. ANOVA results revealed non-significant associations between implementation group and gains in school capacity (F [2, 24] = 1.63; p = .21), class capacity (F [2, 24]=0.20 p = .82), lunchroom capacity (F [2, 24]=0.29; p = .78), and physical education (F [2, 24]=1.45; p = .25). Qualitative data demonstrated that factors within the outer setting (i.e., engaging community partners) facilitated programming. Inner-setting factors (i.e., relationships with administration and staff) influenced implementation. Implementation process themes (e.g., planning, adaptation of resources to meet school capacity/needs, and engaging students as leaders) were cited as key facilitators. Schools discussed factors affecting sustainability, such as school culture and knowledge of school wellness policy. CONCLUSIONS: The results from this implementation study document the importance of allowing schools to adapt programming to meet their local needs, and highlight the strengths of measuring multiple implementation outcomes. Increased support is needed for schools regarding the formation and improvement of wellness policies as a means to enhance sustainability over time.

Socioeconomic status and physical fitness in youth: Findings from the NHANES National Youth Fitness Survey.

This study examined the associations between socioeconomic status (SES) and musculoskeletal (MSF) and cardiorespiratory fitness (CRF) in youth.  The sample consisted of boys and girls between 3-15 years.  SES was categorized utilizing family-income-to-poverty ratio (FIPR).  All analyses were standardized for age and sex.  For each test of physical fitness, SES was used to estimate mean fitness test percentile and 95% confidence intervals, controlling for race/ethnicity and physical activity.  Odds ratios were calculated for the likelihood of having low fitness by SES category.  In general, the high SES group had a better composite MSF, body composition, and CRF profiles than low and moderate SES groups.  Statistically significant differences were identified for relative grip strength, plank, body mass index, and cardiovascular endurance time (all p < 0.05).  Additionally, the odds of low/poor MSF fitness were 1.7 and 1.6 times higher in the low and moderate SES groups (respectively) compared to the children from high SES families.  The moderate SES group had an odds of poor CRF 1.6 times higher than the high SES group as well.  Children and adolescents from high SES families tend to have higher mean fitness and were less likely to have low/poor fitness.

Cross-Presentation of Soluble and Cell-Associated Antigen by Murine Hepatocytes Is Enhanced by Collectrin Expression.

Cross-presentation is a modular series of intracellular events dictating the internalization and subsequent MHC class I (MHC I) display of extracellular Ags. This process has been defined in dendritic cells and plays a fundamental role in the induction of CD8+ T cell immunity during viral, intracellular bacterial, and antitumor responses. Herein, acute viral infection of murine liver with adenovirus, a model for intrahepatic cross-presentation, confirms hepatocytes directly contribute to cross-presentation of Ags and priming the pool of naive CD8+ T cells within the liver microenvironment. Processing of soluble and cell-associated Ags into peptide displayed by MHC I is however defective in hepatocytes lacking collectrin, an intracellular chaperone protein that localizes within the endoplasmic reticulum-Golgi intermediate compartment. Loss of hepatic collectrin expression leads to the diminished cross-priming and expansion of cytolytic antiviral CD8+ T cells. This study demonstrates that collectrin positively regulates processing of engulfed Ags into MHC I:peptide complexes within hepatocytes. Collectrin-mediated cross-presentation supports intrahepatic adaptive antiviral immune responses and may lead to insights into the nature of how the liver acts as a primary site of CD8+ T cell activation.

Feasibility study of the SWITCH implementation process for enhancing school wellness.

BACKGROUND: There is a need to identify strategies that enhance the implementation of evidence-based school wellness intervention programs in real-world settings. The present study evaluates the feasibility of empowering school wellness leaders to deliver an evidence-based, childhood obesity-prevention program called Switch ™. We specifically evaluated the feasibility of a new implementation framework, based on the robust Healthy Youth Places framework, to increase capacity of school leaders to lead school wellness programming. METHODS: The SWITCH (School Wellness Integration Targeting Child Health) implementation process was evaluated in a convenience sample of eight Iowa elementary schools. Teams of three leaders from each school attended an in-person school wellness conference followed by five online webinar sessions delivered by two SWITCH team members. The capacity-building and quality improvement process was designed to empower schools to lead wellness change using methods and concepts from the original 16-week Switch ™ program. School wellness leaders completed checklists on two occasions to assess overall school-level implementation as well as setting-level changes in physical education, classrooms, and the lunchroom. Student acceptability of SWITCH was evaluated by the degree of behavior tracking using an online SWITCH Tracker system that promoted self-monitoring. School acceptability and practicality were assessed through an exit survey completed by school leaders. RESULTS: All school staff reported satisfaction with the SWITCH implementation process. Reports of school- and setting-level implementation were relatively high (2.0 to 2.8 on a 3-point scale) but student engagement, based on use of the online tracking system, varied greatly over time and across schools. Three high implementation schools had average tracking rates exceeding 70% (range: 72-90%) while three low implementation schools had rates lower than 30% (range = 0-23%). CONCLUSIONS: This feasibility study supports the utility of the new implementation framework for promoting school and student engagement with SWITCH. Further testing regarding effectiveness and scale-up of this evidence-based school wellness intervention program is warranted.

Concurrent validation of the Actigraph gt3x+, Polar Active accelerometer, Omron HJ-720 and Yamax Digiwalker SW-701 pedometer step counts in lab-based and free-living settings.

Activity monitors are frequently used to assess activity in many settings. But as technology advances, so do the mechanisms used to estimate activity causing a continuous need to validate newly developed monitors. The purpose of this study was to examine the step count validity of the Yamax Digiwalker SW-701 pedometer (YX), Omron HJ-720 T pedometer (OP), Polar Active accelerometer (PAC) and Actigraph gt3x+ accelerometer (AG) under controlled and free-living conditions. Participants completed five stages of treadmill walking (n = 43) and a subset of these completed a 3-day free-living wear period (n = 37). Manually counted (MC) steps provided a criterion measure for treadmill walking, whereas the comparative measure during free-living was the YX. During treadmill walking, the OP was the most accurate monitor across all speeds (±1.1% of MC steps), while the PAC underestimated steps by 6.7-16.0% per stage. During free-living, the OP and AG counted 97.5% and 98.5% of YX steps, respectively. The PAC overestimated steps by 44.0%, or 5,265 steps per day. The Omron pedometer seems to provide the most reliable and valid estimate of steps taken, as it was the best performer under lab-based conditions and provided comparable results to the YX in free-living. Future studies should consider these monitors in additional populations and settings.

Validity of the SenseWear armband step count measure during controlled and free-living conditions.

BACKGROUND/OBJECTIVE: Advances in technology continue to provide numerous options for physical activity assessment. These advances necessitate evaluation of the validity of newly developed activity monitors being used in clinical and research settings. The purpose of this study was to validate the SenseWear Pro3 Armband (SWA) step counts during treadmill walking and free-living conditions. METHODS: Study 1 observed 39 individuals (17 males, 22 females) wearing an SWA and a Yamax Digiwalker SW-701 pedometer (DIGI) during treadmill walking, utilizing manually counted steps as the criterion. Study 2 compared free-living step count data from 35 participants (17 males, 18 females) wearing the SWA and DIGI (comparison) for 3 consecutive days. RESULTS: During Study 1, the SWA underestimated steps by 16.0%, 10.7%, 5.6%, 6.1%, and 6.5% at speeds of 54 m/min, 67 m/min, 80 m/min, 94 m/min, and 107 m/min, respectively, compared to manually counted steps. During Study 2, the intraclass correlation (ICC) coefficient of mean steps/d between the SWA and DIGI was strong (r = 0.98, p < 0.001). Unlike Study 1, the SWA overestimated step counts during the 3-day wear period by an average of 1028 steps/d (or +11.3%) compared to the DIGI. When analyzed individually, the SWA consistently overestimated step counts for each day (p < 0.05). CONCLUSION: The SWA underestimates steps during treadmill walking and appears to overestimate steps during free-living compared to the DIGI pedometer. Caution is warranted when using the SWA to count steps. Modifications are needed to enhance step counting accuracy.

A cluster-randomized trial comparing two SWITCH implementation support strategies for school wellness intervention effectiveness.

BACKGROUND: The School Wellness Integration Targeting Child Health (SWITCH) intervention has demonstrated feasibility as an implementation approach to help schools facilitate changes in students' physical activity (PA), sedentary screen time (SST), and dietary intake (DI). This study evaluated the comparative effectiveness of enhanced (individualized) implementation and standard (group-based) implementation. METHODS: Twenty-two Iowa elementary schools participated, with each receiving standardized training (wellness conference and webinars). Schools were matched within region and randomized to receive either individualized or group implementation support. The PA, SST, and DI outcomes of 1097 students were assessed at pre- and post-intervention periods using the Youth Activity Profile. Linear mixed models evaluated differential change in outcomes by condition, for comparative effectiveness, and by gender. RESULTS: Both implementation conditions led to significant improvements in PA and SST over time (p < 0.01), but DI did not improve commensurately (p value range: 0.02‒0.05). There were no differential changes between the group and individualized conditions for PA (p = 0.51), SST (p = 0.19), or DI (p = 0.73). There were no differential effects by gender (i.e., non-significant condition-by-gender interactions) for PA (pfor interaction = 0.86), SST (pfor interaction = 0.46), or DI (pfor interaction = 0.15). Effect sizes for both conditions equated to approximately 6 min more PA per day and approximately 3 min less sedentary time. CONCLUSION: The observed lack of difference in outcomes suggests that group implementation of SWITCH is equally effective as individualized implementation for building capacity in school wellness programming. Similarly, the lack of interaction by gender suggests that SWITCH can be beneficial for both boys and girls. Additional research is needed to understand the school-level factors that influence implementation (and outcomes) of SWITCH.

Linked CD4+/CD8+ T cell neoantigen vaccination overcomes immune checkpoint blockade resistance and enables tumor regression.

Therapeutic benefit to immune checkpoint blockade (ICB) is currently limited to the subset of cancers thought to possess a sufficient tumor mutational burden (TMB) to allow for the spontaneous recognition of neoantigens (NeoAg) by autologous T cells. We explored whether the response to ICB of an aggressive low-TMB squamous cell tumor could be improved through combination immunotherapy using functionally defined NeoAg as targets for endogenous CD4+ and CD8+ T cells. We found that, whereas vaccination with CD4+ or CD8+ NeoAg alone did not offer prophylactic or therapeutic immunity, vaccines containing NeoAg recognized by both subsets overcame ICB resistance and led to the eradication of large established tumors that contained a subset of PD-L1+ tumor-initiating cancer stem cells (tCSC), provided the relevant epitopes were physically linked. Therapeutic CD4+/CD8+ T cell NeoAg vaccination produced a modified tumor microenvironment (TME) with increased numbers of NeoAg-specific CD8+ T cells existing in progenitor and intermediate exhausted states enabled by combination ICB-mediated intermolecular epitope spreading. We believe that the concepts explored herein should be exploited for the development of more potent personalized cancer vaccines that can expand the range of tumors treatable with ICB.

Linked CD4 + /CD8 + T cell neoantigen vaccination overcomes immune checkpoint blockade resistance and enables tumor regression.

Therapeutic benefit to immune checkpoint blockade (ICB) is currently limited to the subset of cancers thought to possess a sufficient tumor mutational burden (TMB) to allow for the spontaneous recognition of neoantigens (NeoAg) by autologous T cells. We explored whether the response of an aggressive low TMB squamous cell tumor to ICB could be improved through combination immunotherapy using functionally defined NeoAg as targets for endogenous CD4 + and CD8 + T cells. We found that, whereas vaccination with CD4 + or CD8 + NeoAg alone did not offer prophylactic or therapeutic immunity, vaccines containing NeoAg recognized by both subsets overcame ICB resistance and led to the eradication of large established tumors that contained a subset of PD-L1 + tumor-initiating cancer stem cells (tCSC), provided the relevant epitopes were physically linked. Therapeutic CD4 + /CD8 + T cell NeoAg vaccination produced a modified tumor microenvironment (TME) with increased numbers of NeoAg-specific CD8 + T cells existing in progenitor and intermediate exhausted states enabled by combination ICB-mediated intermolecular epitope spreading. The concepts explored herein should be exploited for the development of more potent personalized cancer vaccines that can expand the range of tumors treatable with ICB.

Evaluation of a Large-Scale School Wellness Intervention Through the Consolidated Framework for Implementation Research (CFIR): Implications for Dissemination and Sustainability.

Background: Numerous studies have tested school-based interventions promoting healthy behaviors in youth, but few have integrated dissemination and implementation (D&I) frameworks. Using D&I frameworks can inform if and how an evidence-based intervention is implemented and maintained and provide strategies to address contextual barriers. Such application is necessary to understand how and why interventions are sustained over time. We evaluated a school wellness initiative called SWITCH® (School Wellness Integration Targeting Child Health) to (1) assess implementation outcomes of adoption, fidelity, and penetration, (2) discern implementation determinants through the Consolidated Framework for Implementation Research (CFIR), and (3) examine differences among inexperienced and experienced schools and influential factors to sustainment. Methods: A total of 52 schools from Iowa, United States enrolled in the 2019-2020 iteration of SWITCH (22 inexperienced; 30 experienced). The CFIR guided the adaptation of mixed methods data collection and analysis protocols for school settings. Specific attention was focused on (1) fidelity to core elements; (2) adoption of best practices; and (3) penetration of behavior change practices. Determinants were investigated through in-depth qualitative interviews and readiness surveys with implementation leaders. A systematic process was used to score CFIR domains (between -2 and +2) indicating positive or negative influence. Independent t-tests were conducted to capture differences between samples, followed by a cross-case analysis to compare determinants data. Inductive coding yielded themes related to sustainment of SWITCH beyond formal implementation support. Results: Experienced schools had higher scores on fidelity/compliance (t = -1.86 p = 0.07) and adoption (t = -2.03 p = 0.04). CFIR determinants of innovation source, culture, relative priority, and leadership engagement were positive implementation determinants, whereas tension for change and networks and communications were negative determinants. Distinguishing factors between experienced and inexperienced schools were Readiness for Implementation and Self-efficacy (experienced significantly higher; p < 0.05). Strategies to enhance sustainability were increasing student awareness/advocacy, keeping it simple, and integrating into school culture. Conclusions: Findings provide specific insights related to SWITCH implementation and sustainability but more generalized insights about the type of support needed to help schools implement and sustain school wellness programming. Tailoring implementation support to both inexperienced and experienced settings will ultimately enhance dissemination and sustainability of evidence-based interventions.

Sleep Moderates Improvements in Mental Health Outcomes in Youth: Building Resilience for Healthy Kids.

PURPOSE: To examine the role of sleep in a school-based resiliency intervention. DESIGN: Single group feasibility study. SETTING: Urban middle school. SUBJECTS: Sixth grade students. INTERVENTION: A total of 285, 11-12-year-old students (70% White, 18% Hispanic, 55% female) participated in the six-week 1:1 Healthy Kids intervention. Youth (n = 248) completed electronic surveys at pre-post the 6-week study assessing mental health parameters and self-reported bed and wake time. MEASURES: Students were categorized as having insufficient sleep opportunity if they reported time in bed of <9 hours per night. ANALYSIS: General linear models examined differences between groups for each mental health parameters pre-post-study. RESULTS: A third of participants (28%) were classified as having insufficient sleep opportunity. Youth with insufficient sleep were more often Hispanic (27% vs 16%; P < .001) and were more often classified with both mild to severe depression and anxiety symptoms (55% vs 35%; P = .004). The health coaching intervention was found to have a significant improvement on overall resilience and self-efficacy only among students who reported sufficient sleep, while no significant intervention effect was found for those students who reported insufficient sleep. CONCLUSIONS: Our findings suggest that youth with poor sleep health may not benefit from school-based resiliency interventions.

Evaluation of a Resiliency Focused Health Coaching Intervention for Middle School Students: Building Resilience for Healthy Kids Program.

INTRODUCTION: Youth mental health issues are a growing public health concern. Resilience has been identified as a mitigating factor for adverse mental health outcomes. Schools have shown an increasing interest in strategies to support students' mental health. The purpose of this study was to evaluate a school-based 1:1 health coaching program designed to build resilience by teaching students coping skills and strategies to increase their self-efficacy. STUDY DESIGN: Single group intervention study with pre/post measures. SETTING/PARTICIPANTS: Sixth grade students (aged 11-12 years) attending an urban middle school. INTERVENTION: Youth participated in up to 6 resiliency-focused, 1:1 health coaching sessions completed over 8 weeks and conducted during the school day. Health coaches utilized motivational interviewing techniques to set and work toward resilience-related goals focused on improving coping skills and self-efficacy with youth during the intervention (January through March 2020). MAIN OUTCOME MEASURES: The Child and Youth Resilience Measure-Revised and other mental health assessments were completed at baseline and immediately following completion of the intervention to evaluate outcomes. Paired sample t-tests and Hedges' g effect sizes were conducted to evaluate intervention effectiveness. Student participation rates were assessed throughout the intervention. RESULTS: 287 youth participated in the study (87% participation rate) and participated in over 85% of health coaching sessions offered. A paired samples t-test revealed the youth resilience significantly increased from pre (M = 75.7, SD = 6.9) to post (M = 77.6, SD = 6.8) intervention (t[257] = 3.73, p < .001) and the size of the effect was medium (g = 0.29, 95% CI = 0.11, 0.46). CONCLUSIONS: The findings demonstrate that health coaching can be an effective strategy for improving resiliency in youth. Future studies evaluating how to effectively disseminate this intervention strategy are planned.

Study protocol for a school-based single group pragmatic trial to promote resilience in youth: Building Resilience for Healthy Kids.

BACKGROUND: There is a growing prevalence of mental health disorders among youth. Helping youth develop skills that promote and support mental well-being is an important strategy for addressing this public health concern. Building Resilience for Healthy Kids (Healthy Kids) is a school-based program designed to improve resiliency in youth aged 9-13 years old using an innovative health coaching framework. METHODS: Healthy Kids is a multi-phased intervention that aims to improve youth resilience using a 6-week, 1:1 health coaching program. The program develops youth resilience and was derived from models for developing youth resilience: Positive Relationships, Coping, Skill Development, Healthy Lifestyle, Sense of Culture, and Connectedness. Effectiveness of the intervention will be evaluated using a single-group, pragmatic trial design with pretest-posttest and follow-up assessments up to 12 months. Process measures will evaluate youth's acceptance and satisfaction of the program and attendance rates. Effectiveness will be evaluated by examining changes in resilience and mental health indicators from pre-to-post program and tracking sustainment of changes in mental health indicators over time. DISCUSSION: Given the pragmatic nature of the study design to work with generally healthy populations of students, we expect small, but sustainable, improvements in youth resilience to be achieved through the intervention. Further, this study will provide insight into the potential effectiveness of using health coaching as a strategy to support and promote youth mental well-being in school settings. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04202913. Registered December 18, 2019.

TLR9 Sensing of Self-DNA Controls Cell-Mediated Immunity to Listeria Infection via Rapid Conversion of Conventional CD4+ T Cells to Treg.

CD4+ T lymphocytes are crucial for controlling a range of innate and adaptive immune effectors. For CD8+ cytotoxic T lymphocyte (CTL) responses, CD4+ T cells can function as helpers (TH) to amplify magnitude and functionality or as regulatory cells (Treg) capable of profound inhibition. It is unclear what determines differentiation to these phenotypes and whether pathogens provoke alternate programs. We find that, depending on the size of initial dose, Listeria infection drives CD4+ T cells to act as TH or induces rapid polyclonal conversion to immunosuppressive Treg. Conversion to Treg depends on the TLR9 and IL-12 pathways elicited by CD8α+ dendritic cell (DC) sensing of danger-associated neutrophil self-DNA. These findings resolve long-standing questions regarding the conditional requirement for TH amongst pathogens and reveal a remarkable degree of plasticity in the function of CD4+ T cells, which can be quickly converted to Tregin vivo by infection-mediated immune modulation.

The Importance of Self-Monitoring for Behavior Change in Youth: Findings from the SWITCH® School Wellness Feasibility Study.

School Wellness Integration Targeting Child Health (SWITCH®) is a school wellness implementation initiative focused on building capacity for schools to plan and coordinate wellness programming. Grounded in Social Cognitive Theory (SCT), the purpose of this study was to evaluate the utility of the web-based, self-regulation system on physical activity (PA) behavior outcomes. At pre-test and post-test, students in SWITCH® schools (n = 8) completed the online Youth Activity Profile (YAP) to assess PA and sedentary behavior (SB). Students (n = 513) were categorized into high or low self-monitoring groups (using a median split) based on their use of the web-based self-regulation platform. Linear mixed models were used to assess differences in moderate-to-vigorous PA (MVPA) and sedentary behavior, with school, classroom, student, time-by-school, and time-by-classroom random effects and main and interaction fixed effects for student self-monitoring, gender, and time. Significant self-monitoring-by-time interactions were observed for estimates of PA F(1, 477) = 5.55, p = 0.02 and SB F(1, 477) = 4.90, p = 0.03. Students in the high self-monitoring group had larger gains in PA per day and larger declines in hours per day of sedentary screen time behavior compared to students in the low self-monitoring group. These findings support the utility of web-based self-regulation for facilitating PA change in youth.

Obesity and Insulin Resistance Screening Tools in American Adolescents: National Health and Nutrition Examination Survey (NHANES) 1999 to 2010.

OBJECTIVE: To identify which feasible obesity and insulin resistance (IR) screening tools are most strongly associated in adolescents by using a nationally representative sample. METHODS: Adolescents aged 12.0 to 18.9 years who were participating in the National Health and Nutrition Examination Survey (NHANES) (n=3584) and who were measured for height, weight, waist circumference (WC), triceps and subscapular skinfold thickness, glycated hemoglobin, fasting glucose (FG) and fasting insulin (FI) level were included. Adolescents were split by gender and grouped by body mass index (BMI) percentile. Age- and gender-specific classifications were constructed for each obesity screening tool measure to account for growth and maturation. General linear models were used to establish groups objectively for analysis based on when IR began to increase. Additional general linear models were used to identify when IR significantly increased for each IR measure as obesity group increased and to identify the variance accounted for among each obesity-IR screening tool relationship. RESULTS: As the obesity group increased, homeostasis model assessment-insulin resistance (HOMA-IR) and FI significantly increased, while FG increased only (above the referent) in groups with BMI percentiles ≥95.0, and glycated hemoglobin level did not vary across obesity groups. The most strongly associated screening tools were WC and FI in boys (R(2)=0.253) and girls (R(2)=0.257). FI had the strongest association with all of the obesity measures. BMI associations were slightly weaker than WC in each in relation to IR. CONCLUSIONS: Our findings show that WC and FI are the most strongly associated obesity and IR screening tool measures in adolescents. These feasible screening tools should be utilized in screening practices for at-risk adolescents.