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Treatment for neuromuscular hip dysplasia (NMHD) typically involves osteotomies of the proximal femur and/or pelvis, and the potential for significant volume blood loss is high. Tranexamic acid (TXA) functions as an antifibinolytic and has been shown to reduce bleeding in many operative settings. Retrospective evidence for the use of TXA in children undergoing NMHD reconstruction is inconclusive, and to our knowledge, prospective evaluation has never been performed. The purpose of this study was to examine the effectiveness of TXA use on intra- and postoperative outcomes during bony reconstruction for NMHD. In this matched comparative study, a prospective cohort of patients undergoing bony reconstruction for NMHD who were given TXA was enrolled and then matched to a retrospective cohort who previously underwent the same surgery without administration of TXA. The primary outcome variable was a change in perioperative hemoglobin values from preoperative to 1 day postoperatively. Secondary objectives were percent loss of estimated blood volume, postoperative transfusion requirements, and length of hospital stay. Forty-eight patients, 24 in each cohort, were included in the analyses. Mean age at surgery was 7.09 years (±2.5). Fifty percent of each cohort underwent bilateral varus derotational osteotomy with pelvic acetabuloplasty. No statistical differences were found in postoperative hemoglobin differences (P = 0.18), length of hospital stay (P = 0.45), or blood transfusion requirements (P = 0.56) between cohorts. Intraoperative administration of TXA to patients undergoing bony reconstruction for NMHD was not found to reduce postoperative blood loss or requirement for blood transfusion. Future studies should employ a larger, prospective randomized controlled trial to verify these findings., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Multi-segment foot models have been used to quantify foot kinematics during walking. However, walking kinematics is not sufficient to assess hindfoot flexibility (available range of hindfoot varus-valgus motion). The modified Shriners Hospitals for Children - Greenville (mSHCG) foot model has been used to quantify hindfoot flexibility with Coleman block test (peak hindfoot valgus) and Root test (peak hindfoot varus). Sensitivity of mSHCG foot model to detect clinically relevant difference in hindfoot flexibility measures for planovalgus (PV) and cavovarus (CV) feet has not been demonstrated., Research Question: Can mSHCG foot model detect statistically significant difference in hindfoot flexibility measures between PV, CV and typically developing (TD) feet?, Methods: Hindfoot flexibility assessment was completed for 32 PV (37 feet), 27 CV (37 feet) and 20 TD (40 feet) individuals. Hindfoot position relative to tibia in coronal plane was measured in three postures: standing, heel raise and Coleman block test. Radiographic measures in standing position were also completed for PV and CV individuals and their correlation with hindfoot flexibility measures were evaluated., Results: Statistically significant (p<0.001) differences were observed between three groups (TD, PV, CV) in all three hindfoot flexibility measures- (i) Hindfoot varus in standing position (ii) Peak hindfoot varus in heel raise and (iii) Peak hindfoot valgus in Coleman block test. There was relatively stronger correlation (R 2 =0.407-0.854) between three radiographic measures and hindfoot varus in standing position. Correlation between hindfoot range of motion towards valgus from standing to Coleman block test and the three radiographic measures was weaker (R 2 =0.2329-0.3042)., Significance: Hindfoot flexibility assessment can detect statistically significant difference between PV, CV and TD feet and provides additional information about available dynamic range of motion of hindfoot in the coronal plane that cannot be predicted from radiographic measures. Therefore, hindfoot flexibility assessment may assist in treatment planning of foot deformities., Competing Interests: Declaration of Competing Interest Authors have no conflicts of interest to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: Effective public health interventions targeting factors that influence physical activity are urgently needed to reduce the age-related decline in physical activity in youth. The purpose of this study was to identify associations between physical activity and a set of potential influences on physical activity in children as they transition from elementary to high school., Methods: Participants were 951 children from South Carolina school districts who completed outcome and independent variable measures on at least two time points from the 5th to 11th grades in 2010-2017. The primary outcome variable was physical activity, measured by accelerometry. Independent variables included a comprehensive set of variables in the child, parent/home, school, and community domains. Children, parents and school administrators, and staff completed questionnaires to assess psychosocial and home, school, and neighborhood environmental influences. Growth curve analyses identified independent variables associated with physical activity over time, either as a main effect or as an interaction with age., Results: As main effects, self-efficacy, self-schema, sport participation, weekday outdoor hours, importance of child participating in sports and physical activity, safe to play outside, and Physical Activity Resource Assessment weighted score were positively associated with physical activity. The associations between physical activity and enjoyment motivation, appearance motivation, weekend outdoor time, and home equipment exhibited significant interactions with age. Enjoyment motivation influenced physical activity during the earlier years, whereas the remaining three variables influenced physical activity in the later years., Conclusions: Interventions should target multiple domains of influences that may vary by age., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Sports Medicine.)

Purpose : To identify practice and social contextual factors that associate with physical activity (PA) levels of children during their participation in a youth soccer program. Methods : Twenty-seven youth soccer teams serving children ages 6-11 years participated. Research staff directly observed and recorded PA intensity and practice and social contextual factors using momentary time-sampling procedures. Each team was observed for 1 practice, during which approximately 6 children were each observed for twenty 30-s observation blocks (10-s observation, 20-s recording). In total, children were observed for 3,102 intervals. Multilevel logistic regression analyses were conducted to describe associations between PA intensity and practice and social contexts. Interaction terms were introduced into the models to determine if the associations differed across girls-only, boys-only, and coed teams. Results : A total of 158 children were observed across the 27 teams. Children were more likely to engage in moderate or vigorous PA while performing fitness (Odds Ratio [OR], 9.9, 95% CI = 5.34-18.04), game (OR, 4.0, 95% CI = 2.88-5.66), warm-up (OR, 2.8, 95% CI = 1.85-4.11), and drill (OR, 1.9, 95% CI = 1.41-2.67) activities compared to tactic/instructional activities. The associations between PA intensity levels and practice and social contexts did not differ across girls-only, boys-only, and coed teams. Conclusions : Fitness activities and full-team game play were associated with higher PA intensity levels during children's participation in youth soccer practices. Youth sport practice protocols can be modified to increase children's physical activity.

Children with arthrogryposis multiplex congenita (AMC) often demonstrate growth differences compared with typically developing (TD) children. However, growth charts have not been developed for this population. The purpose of this study was to create AMC-specific growth charts and to compare these values to those of TD children. A retrospective review of height/length and weight for 206 children with AMC was performed. Growth charts were developed and stratified over seven percentiles; these were then compared with growth charts of TD children. Children with AMC tend to be smaller in stature and weight compared with TD children, particularly in the first 36 months of life. Thereafter, weight values trend toward the 50th percentile of TD children, but height/length values persist around the 5th percentile of TD children. The development of AMC-specific growth charts provides health care providers an objective tool to evaluate growth patterns of patients with AMC., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Arthrogryposis (AMC) is a descriptive term to characterize a child born with multiple joint contractures. Treatment aims to improve functional independence, yet the literature objectively describing functional independence in this population is scarce. This study aimed to describe the functional independence of children with AMC through the lens of the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT) and observational activities of daily living (ADL) tasks., Methods: Patients with AMC between the ages of 3 and 12 years participated in this prospective study. Parents completed the PEDI-CAT while a trained occupational therapist observed children as they completed a checklist of functional ADL tasks. Patients were grouped according to developmental age groups: "preschoolers" (3 to 5 y), "early school-age" (6 to 9 y), and "late school-age" (10 to 12 y). Patient's PEDI-CAT normative scores were described, comparing the study population to typically developing children, and differences in each domain were examined between developmental age groups. The observed ADL tasks completed were also described, and differences in scores were examined between developmental age groups., Results: Forty-four patients (mean age of 7±2.86 y) were enrolled. The distribution between age groups was nearly even. Mean daily activities T -score for patients with AMC was 25.80±11.98 and the mean mobility T -score was 17.39±9.77. Late school-age children scored significantly lower than preschool-age children in both of these domains ( P <0.01). Observed ADL tasks demonstrated a high level of required assistance for patients (range: 27.3% to 61.4%), although older school-age children did show greater independence with tested activities than preschool-age children ( P =0.05)., Conclusion: Children with AMC are significantly limited in functional independence, particularly regarding age-appropriate daily activities and mobility. Outcomes from this study provide a reference to help gauge the results of nonoperative and surgical treatment toward improving functional independence in this population., Level of Evidence: Level III: prognostic study., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: The purposes of this study were to examine indications, radiographic outcomes, and clinical complications for primary arthrodesis of the great toe interphalangeal (IP) joint in young patients., Background: Hallux valgus interphalangeus deformity of the great toe is uncommon in the pediatric population and often requires fusion of the IP joint., Methods: A retrospective review of patients, ages 8 to 19 years, who underwent operative fusion of the great toe IP joint, and had >1 year radiographic follow-up was performed. Medical records and radiographs were reviewed to determine indications for surgery, concomitant procedures, success of fusion, complications, and need for revision procedures or elective hardware removal. Differences between pre and postradiographic outcomes for the hallux valgus angle, IP angle, and intermetatarsal angle were analyzed., Results: Twenty-seven patients (31 feet) were included in the analyses. The average age at fusion surgery was 14.9 years (SD ± 2.3) with a mean follow-up visit of 35.2 months. The most common indications for fusion of the great toe IP joint were pain and deformity. Kirschner wire fixation was utilized in 7 cases, with the remaining 24 cases fixed with a single retrograde cannulated screw. Fifty-five concomitant toe and foot procedures were performed in 21 feet (68%) to address additional foot and toe deformity. Successful fusion occurred in 30 of 31 toes after the primary fusion. Patient satisfaction with the toe position and diminished pain were high (94.1%). Significant improvement was noted in the measure of the IP angle ( P < 0.001), with minimal clinical change in the hallux valgus angle ( P = 0.24) or the intermetatarsal angle ( P = 0.03)., Conclusions: Hallux valgus interphalangeus of the great toe was successfully managed with the fusion of the IP joint. Single screw fixation or the use of Kirschner wires led to similar outcomes. Hardware-related issues with the use of screws were the most common adverse outcome. Patients should be made aware of the possible need for hardware removal after fusion utilizing screw fixation., Level of Evidence: Level IV-a retrospective case series., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The U.S. military veteran population experiences elevated rates of suicide relative to demographically matched community samples. Understanding suicide risk factors in veterans is therefore of critical importance. Accordingly, the Veterans Health Administration (VHA) has implemented elevated vigilance for suicidal ideation in its health care. One potential risk factor for suicidal ideation or behavior may be attention-deficit/hyperactivity disorder (ADHD), which is frequently characterized by impaired impulse control and experience of intense emotions. To determine whether ADHD, as diagnosed by VHA assessment, may represent an independent or interactive risk factor for suicidal ideation or suicide attempt, we examined potential linkages between VHA-assessed symptomatology of ADHD and suicide attempts or ideation, either with or without the presence of comorbid VHA-assessed psychiatric symptomatology. In a retrospective chart review, we compared severity of clinician-rated suicide risk in 342 veterans (82.5% male) referred to a VHA medical center for ADHD assessment, of whom 198 were diagnosed with ADHD. Contrary to our preregistered hypotheses, there were no main or additive effects of ADHD in terms of increased suicidal ideation, clinician-rated suicide risk or in incidence of lifetime suicide attempt. Motoric impulsivity in neurocognitive testing also showed no relationship with suicide risk or attempts. Rather, consistent with previous literature, presence of a mood disorder or other non-ADHD psychopathology was linked to suicide risk ratings and attempts, irrespective of presence of ADHD symptoms. These data suggest that once comorbid symptomatology such as depression is controlled for, ADHD alone is not associated with elevated suicidal ideation or attempts in veterans. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Background: Excessive knee flexion during stance in children with cerebral palsy is often treated by surgical hamstrings lengthening. Pre-operative hamstrings muscle-tendon length can be estimated from kinematics and often used for decision making to rule out surgical lengthening if peak hamstrings muscle-tendon length is 'Not Short'., Research Question: If peak hamstrings muscle-tendon length is within two standard deviations of typical, is that a sufficient indicator to rule out surgical hamstrings lengthening?, Methods: Three motion analysis centers retrospectively identified children with cerebral palsy, age 6-17 years, who had consecutive gait analyses with knee flexion at initial contact > 20° and popliteal angle > 35° at initial study. Three groups were considered: Medial Hamstrings Lengthening (MHL), Medial and Lateral Hamstrings Lengthening (MLHL), no surgical intervention (Control). Peak hamstrings muscle-tendon length at initial gait study was computed and categorized as 'Short' or 'Not Short'. Two outcomes variables were considered: change in peak knee extension (PKE) and change in pelvic tilt. Univariate comparisons of all variables were assessed along with a multivariate stepwise regression analysis to identify pre-operative characteristics that may predict post-operative improvement., Results: 440 individuals met inclusion criteria. Percentage of individuals with improved PKE by grouping were- MHL-'Short': 60%, MHL-'Not Short': 65%, MLHL-'Short': 74%, MLHL-'Not Short': 74%, Control 'Short': 20%, Control 'Not Short': 19%. Percentage of individuals with worsened pelvic tilt were- MHL-'Short': 25%, MHL-'Not Short': 11%, MLHL-'Short': 42%, MLHL-'Not Short': 21% with significantly more individuals in MHL-'Short' subgroup compared to MHL-'Not Short'. Multivariate analysis suggested that pre-operative pelvic tilt and weak hip extensor strength have the largest effect on predicting post-operative increase in APT. Peak muscle-tendon length was not a significant predictor of post-operative knee kinematics or increase in APT., Significance: This study suggests that hamstrings muscle-tendon length criteria by itself is not a sufficient indicator to recommend against hamstrings lengthening., Competing Interests: Declaration of Competing Interest Authors have no conflicts of interest to disclose., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Children with cerebral palsy (CP) and neuromuscular hip dysplasia (NMHD) frequently require hip reconstruction including femoral and pelvic osteotomies. Outcomes and complications in CP patients with NMHD who underwent varying degrees of hip reconstruction surgeries were examined. Ninety-nine patients with a diagnosis of CP who underwent surgical management of NMHD over a 15-year period (2005-2020) were reviewed. Three patient cohorts with varying degrees of surgery were analyzed including: (1) unilateral femoral osteotomy with pelvic osteotomy; (2) bilateral femoral osteotomy with unilateral pelvic osteotomy; and (3) simultaneous bilateral femoral osteotomy and bilateral pelvic osteotomy. Data points included operative (OR) time, length of stay (LOS), estimated blood loss (EBL), and transfusion requirement. Complications during the perioperative and postoperative periods were identified and graded by severity. Increased EBL, need for transfusion, OR time, and LOS were observed more frequently in patients undergoing bilateral reconstruction. Complication rates were high for all three cohorts, with 87% of cases in the bilateral pelvic osteotomy cohort experiencing ≥1 complication. However, 90% of these were considered grade I or II and required no or minimal intervention. The average postoperative migration index at final follow-up for treated hips was significantly less in bilateral pelvic osteotomy cases. Patients with CP and bilateral NMHD can be safely managed with bilateral simultaneous comprehensive reconstruction. The data presented in this study can help both surgeons and families anticipate a more accurate postoperative course. Level of evidence: III., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The dynamic motor control (walk-DMC) index during walking is a measure of the complexity of muscle activation pattern. Ankle Foot Orthoses (AFO) are frequently used to improve the gait of children with Cerebral Palsy (CP) and Idiopathic Toe Walking (ITW). The purpose of this study was to assess the change in walk-DMC index secondary to AFO use., Research Question: Does the change in walk-DMC reflect the change in walking kinematics with the use of AFO., Methods: Individuals with diagnosis of CP or ITW with gait analysis data available for barefoot and AFO condition were retrospectively identified. For each individual, the walk-DMC index, Gait Deviation Index (GDI) and Gait Variable Scores (GVS) of knee and ankle kinematics were computed for BF and AFO conditions. Paired t-tests were used to compare key variables between BF and AFO conditions. Multi-variate stepwise regression analysis was performed to identify variables that may predict the increase in walk-DMC between BF and AFO condition., Results: 253 individuals were included in the study. For CP individuals (n = 208), statistically significant but quantitatively minimal improvement was observed in walk-DMC (1 ± 9), GDI (2 ± 9) and ankle GVS (2 ± 7). For ITW individuals (n = 45), larger improvements were observed in walk-DMC (11 ± 13), GDI (9 ± 11) and ankle GVS (6 ± 7). Diagnosis of ITW, use of Solid-AFO and Posterior Leaf Spring-AFO were the significant predictor of increase in walk-DMC with AFO. Higher ankle GVS at BF condition (larger deviation from TD) led to larger increase in walk-DMC. Higher knee GVS (larger deviation from TD) led to smaller increase in walk-DMC., Significance: Use of AFO can lead to improvement in walking kinematics that is reflected in increase in walk-DMC with AFO compared to BF for ITW individuals. The change in kinematics and walk-DMC with use of AFO was minimal for CP individuals., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Cardiorespiratory fitness (CRF) plays a significant role in health and academic performance in youth. The purpose of this study was to examine the longitudinal relationship between CRF and academic performance from fifth to eighth grade among a large, diverse, and state-wide cohort of students, and to determine the extent to which the relationship between change in CRF and academic performance is moderated by poverty status., Methods: CRF and academic performance data were obtained for a retrospective state-wide cohort of 11,013 students with baseline (fifth grade, school year 2015-2016) and follow-up (eighth grade, school year 2018-2019) data. Analysis of covariance was used to examine the association between changes in CRF over a 3-year follow-up period and eighth grade academic performance., Results: After adjusting for covariates, change in CRF and poverty status were positively and significantly associated with eighth grade academic performance. Poverty status did not significantly moderate the association between changes in CRF and academic performance., Conclusions: Schools should prioritize evidence-based policies and programs that optimize students' access to high quantity and quality physical activity throughout the school day. Such efforts can improve and maintain student CRF and thus academic performance outcomes., (© 2022 American School Health Association.)

Background: To describe objectively measured physical activity (PA) in infants, and to identify demographic, behavioral, and environmental factors associated with infants' PA. Methods: Participants were 6-7-month-old infants and their mothers ( N  = 143 dyads) from two Southeastern US counties. Infant measures included PA assessed by accelerometers at ankle and waist sites, motor developmental status ( i.e. , stationary and locomotion), and anthropometric characteristics ( i.e. , height and weight). Mothers provided information on home environment, child care settings, and family demographic factors. PA levels were compared across demographic subgroups. Correlation coefficients described associations between PA and continuous variables, including motor developmental status and anthropometric characteristics. Multiple linear regression analyses examined factors found to be independently associated with PA. Results: Infants' PA counts were greater at the ankle (77,700 counts/hr) vs. the waist site (32,500 counts/hr). In univariate analyses, a diverse set of environmental, behavioral, and infant-level demographic factors were found to be significantly associated with PA at the ankle site. Multivariate analyses indicated that more advanced motor development status ( B  = 666.3 ± 329.8, p  < 0.05), attendance at home child care settings ( B  = -13,724.4 ± 5083.9, p  < 0.05), greater exposure to tummy time ( B  = 213.5 ± 79.9, p  < 0.05), and white racial/ethnic composition ( B  = -19,953.4 ± 5888.5, p  < 0.01) were independently, associated with infants' PA. Conclusions: In 6-7-month-old infants, objectively measured PA was found to be associated with motor developmental status and physical and social environmental factors, including both demographic moderators and factors that are influenced by parents and caregivers. Longitudinal studies are needed to determine if these relationships persist or change as infants develop.

Objective: Examine factors associated with recovery from posttraumatic stress disorder (PTSD) and evaluate the role of deployment mild traumatic brain injury (mTBI) in the relationship between PTSD recovery and functional outcomes., Method: Post 9/11 combat veterans with lifetime history of PTSD ( N = 124, 84.7% male) completed the Mid-Atlantic MIRECC Assessment of Traumatic Brain Injury (MMA-TBI), Salisbury Blast Interview (SBI), Clinician Administered PTSD scale (CAPS-5), cognitive assessment battery, and measures of depression, PTSD symptoms, neurobehavioral symptoms, sleep quality, pain interference, and quality of life., Results: Analyses of variance (ANOVA) results revealed significant differences in most behavioral health outcomes based on PTSD recovery, with participants who have recovered from PTSD showing less severe neurobehavioral and depressive symptoms, better sleep quality, less functional pain interference, and higher quality of life. No differences were found in cognitive functioning between those who have recovered from PTSD and those who have not. History of deployment mTBI did not significantly moderate the relationship between PTSD recovery and most functional and cognitive outcomes with the exception of 2 measures of processing speed. Specifically, among participants with history of deployment mTBI, those who have recovered from PTSD displayed better cognitive functioning than those who have not. Additionally, participants who have not recovered from PTSD had higher levels of blast exposure during military service., Conclusions: PTSD recovery was associated with better psychological functioning and higher quality of life, but not with objective cognitive functioning. Deployment mTBI history moderated only the relationship between PTSD recovery status and tests of processing speed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Background: The purpose of the study was to examine the associations among cardiorespiratory fitness (CRF), weight status and academic achievement in youth, and to determine if these relationships are moderated by poverty status., Methods: The sample included 5th (N = 27,791) and 8th grade (N = 16,047) South Carolina students. Academic achievement was assessed using a state-wide assessment and classified into 2 categories (ie, does not meet/approaches standards vs meets/exceeds standards). CRF was assessed and expressed as Healthy Fitness Zone (HFZ) or Needs Improvement/Needs-Improvement-Health Risk. Students' demographics and poverty status were reported. Multilevel logistic regression analyses were used to examine the association between CRF, weight status and academic achievement. Interaction terms were introduced into the final models. Analyses were performed separately by grade level and academic subject., Results: The CRF was significantly associated with the odds of meeting/exceeding academic standards after controlling for covariates and adjusting for weight status. The relationship between CRF and academic achievement varied significantly by poverty status. After adjustment for CRF, weight status was not significantly associated with academic achievement., Conclusions: The odds of achieving academic standards were significantly higher among students achieving CRF HFZ regardless of poverty status. CRF may partially mitigate the adverse effect of poverty on academic achievement., (© 2020, American School Health Association.)

Background: Physical activity is known to provide important health benefits in children ages 3 years and above, but little is known about the effects of physical activity on health in very young children under age 3. LAUNCH (Linking Activity, Nutrition, and Child Health) is a study designed to expand the body of knowledge on development of physical activity behavior and associations between physical activity and other health characteristics as children transition from infancy to preschool age., Methods: Physical activity and sedentary behavior will be measured objectively in young children over a period of 30 months. Each child will complete a measurement protocol at 6, 12, 18, 24, 30 and 36 months of age. The following factors will be measured at each time point: physical activity, sedentary behavior, anthropometric characteristics, and motor developmental status. Objectively-measured sleep behavior will be included as an optional component of the protocol. Parents will provide information on demographic factors, parenting behaviors, home and childcare characteristics, and the child's dietary and sleep behaviors., Discussion: LAUNCH will employ a longitudinal study design and objective measures of physical activity, sedentary behavior and sleep in examining developmental trends for those characteristics in children between the ages of 6 and 36 months. Associations among physical activity, sedentary behavior, sleep, and weight status will be examined. Findings will inform public health guidance and intervention strategies for very young children.

Objectives: To examine associations between sport participation, and objectively assessed physical activity and sedentary behavior in youth during the transition from middle school to high school., Design: Longitudinal study with 2-year follow-up., Methods: Sport participation and accelerometer-measured physical activity and sedentary behavior were assessed in 306 children (122 males, 184 females) when they were in 7th and 9th grades (mean age of 12.5 ± 0.5 years)., Results: Sport participation and physical activity declined from 7th to 9th grade, but total physical activity (d = 0.38, p < 0.0001) and moderate-to-vigorous physical activity (d = 0.26, p = 0.0004) remained higher in sport participants compared to non-participants. In 9th grade, the full sample of sport participants compared to non-participants had higher levels of total physical activity (20.7 min/h vs. 18.5 min/h) and moderate-to-vigorous physical activity (1.8 min/h vs. 1.6 min/h). Sex-specific analysis revealed similar patterns in both females and males. Sedentary behavior remained lower (d = -0.37, p = <0.0001) in the full sample of sport participants compared to non-participants (39.8 min/h vs. 41.7 min/h) in 9th grade. Similar patterns were observed in both females and males., Conclusions: Children's participation in sport is associated with greater levels of physical activity and lower levels of sedentary behavior during the transition from middle school to high school. Promoting children's participation in sports could be an effective public health strategy to help children meet the current physical activity guideline., (Copyright © 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

The ATR (ATM (ataxia telangiectasia mutated) and rad3-related) checkpoint kinase is considered critical for signalling DNA replication stress and its dysfunction can lead to the neurodevelopmental disorder, ATR-Seckel syndrome. To understand how ATR functions during neurogenesis, we conditionally deleted Atr broadly throughout the murine nervous system, or in a restricted manner in the dorsal telencephalon. Unexpectedly, in both scenarios, Atr loss impacted neurogenesis relatively late during neural development involving only certain progenitor populations. Whereas the Atr-deficient embryonic cerebellar external germinal layer underwent p53- (and p16(Ink4a/Arf))-independent proliferation arrest, other brain regions suffered apoptosis that was partially p53 dependent. In contrast to other organs, in the nervous system, p53 loss did not worsen the outcome of Atr inactivation. Coincident inactivation of Atm also did not affect the phenotype after Atr deletion, supporting non-overlapping physiological roles for these related DNA damage-response kinases in the brain. Rather than an essential general role in preventing replication stress, our data indicate that ATR functions to monitor genomic integrity in a selective spatiotemporal manner during neurogenesis.

The MRN complex (Mre11/RAD50/NBS1) and ATM (ataxia telangiectasia, mutated) are critical for the cellular response to DNA damage. ATM disruption causes ataxia telangiectasia (A-T), while MRN dysfunction can lead to A-T-like disease (ATLD) or Nijmegen breakage syndrome (NBS). Neuropathology is a hallmark of these diseases, whereby neurodegeneration occurs in A-T and ATLD while microcephaly characterizes NBS. To understand the contrasting neuropathology resulting from Mre11 or Nbs1 hypomorphic mutations, we analyzed neural tissue from Mre11(ATLD1/ATLD1) and Nbs1(DeltaB/DeltaB) mice after genotoxic stress. We found a pronounced resistance to DNA damage-induced apoptosis after ionizing radiation or DNA ligase IV (Lig4) loss in the Mre11(ATLD1/ATLD1) nervous system that was associated with defective Atm activation and phosphorylation of its substrates Chk2 and p53. Conversely, DNA damage-induced Atm phosphorylation was defective in Nbs1(DeltaB/DeltaB) neural tissue, although apoptosis occurred normally. We also conditionally disrupted Lig4 throughout the nervous system using Nestin-cre (Lig4(Nes-Cre)), and while viable, these mice showed pronounced microcephaly and a prominent age-related accumulation of DNA damage throughout the brain. Either Atm-/- or Mre11(ATLD1/ATLD1) genetic backgrounds, but not Nbs1(DeltaB/DeltaB), rescued Lig4(Nes-Cre) microcephaly. Thus, DNA damage signaling in the nervous system is different between ATLD and NBS and likely explains their respective neuropathology.