In vivo selection in non-human primates identifies AAV capsids for on-target CSF delivery to spinal cord.

Systemic administration of adeno-associated virus (AAV) vectors for spinal cord gene therapy has challenges including toxicity at high doses and pre-existing immunity that reduces efficacy. Intrathecal (IT) delivery of AAV vectors into cerebral spinal fluid can avoid many issues, although distribution of the vector throughout the spinal cord is limited, and vector entry to the periphery sometimes initiates hepatotoxicity. Here we performed biopanning in non-human primates (NHPs) with an IT injected AAV9 peptide display library. We identified top candidates by sequencing inserts of AAV DNA isolated from whole tissue, nuclei, or nuclei from transgene-expressing cells. These barcoded candidates were pooled with AAV9 and compared for biodistribution and transgene expression in spinal cord and liver of IT injected NHPs. Most candidates displayed increased retention in spinal cord compared with AAV9. Greater spread from the lumbar to the thoracic and cervical regions was observed for several capsids. Furthermore, several capsids displayed decreased biodistribution to the liver compared with AAV9, providing a high on-target/low off-target biodistribution. Finally, we tested top candidates in human spinal cord organoids and found them to outperform AAV9 in efficiency of transgene expression in neurons and astrocytes. These capsids have potential to serve as leading-edge delivery vehicles for spinal cord-directed gene therapies.

The effect of point-of-care ultrasound on length of stay in the emergency department in children with neck swelling.

BACKGROUND: Ultrasound is the imaging modality of choice in children presenting to the emergency department (ED) with soft tissue neck swelling. Point of care ultrasound (POCUS) has good accuracy when compared to comprehensive radiology department ultrasound (RADUS). POCUS could potentially improve ED length of stay (LOS) by improving efficiency. We aimed to evaluate the LOS of pediatric patients seen in ED with soft tissue neck swelling who received POCUS compared to RADUS. We determined unscheduled 30-day return visit rates in both groups as a balancing measure. METHODS: We performed a retrospective review of the electronic medical record for our cross-sectional study of discharged patients ≤21 years of age who had a neck ultrasound performed by a credentialed POCUS physician or by the radiology department between July 2014 and January 2020. We included patients who had both POCUS and RADUS in the POCUS group. We compared median ED LOS in both groups using the Mann Whitney U test and proportion of unscheduled return visits to the ED in both groups using odds ratio and 95% CI. RESULTS: There were 925 patients: 76 with only POCUS, 6 with POCUS and RADUS, and 843 with only RADUS performed. Median LOS in the POCUS group was 68.5 min (IQR 38.3120.3) versus 154.0 min (IQR 111.0, 211.0) in the RADUS group (p < 0.001). Return visit overall was 7.6%: 13.2% in the POCUS group versus 7.1% in the RADUS group (p = 0.07). CONCLUSION: Pediatric patients evaluated in the ED for soft tissue neck swelling had a shorter LOS with POCUS than with RADUS without a statistically significant increase in 30-day return visits. We suggest a "POCUS First" approach to the care of these patients.

Diagnosing Acute Heart Failure in the Pediatric Emergency Department Using Point-of-Care Ultrasound.

BACKGROUND: Acute heart failure (AHF) in children is associated with significant disease burden with high rates of morbidity, mortality, and resource utilization. These children often present to the emergency department with clinical features that mimic common childhood illnesses. Cardiac point-of-care ultrasound (POCUS) can be an effective tool for rapidly identifying abnormal cardiac function. CASE REPORTS: This case series documents 10 children presenting with AHF between 2016 and 2019 and demonstrates how pediatric emergency physicians used cardiac POCUS to expedite their diagnosis, management, and disposition. All cardiac POCUS was performed before comprehensive echocardiograms were completed. One case is described in detail; the other cases are summarized in a Table. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Early recognition of AHF is critical to reduce pediatric morbidity and mortality. With proper training, cardiac POCUS can be an effective adjunct and should be considered for the early diagnosis and treatment of infants and children with AHF.

Partial FMRP expression is sufficient to normalize neuronal hyperactivity in Fragile X neurons.

Fragile X syndrome (FXS) is the most common genetic form of intellectual disability caused by a CGG repeat expansion in the 5'-UTR of the Fragile X mental retardation gene FMR1, triggering epigenetic silencing and the subsequent absence of the protein, FMRP. Reactivation of FMR1 represents an attractive therapeutic strategy targeting the genetic root cause of FXS. However, largely missing in the FXS field is an understanding of how much FMR1 reactivation is required to rescue FMRP-dependent mutant phenotypes. Here, we utilize FXS patient-derived excitatory neurons to model FXS in vitro and confirm that the absence of FMRP leads to neuronal hyperactivity. We further determined the levels of FMRP and the percentage of FMRP-positive cells necessary to correct this phenotype utilizing a mixed and mosaic neuronal culture system and a combination of CRISPR, antisense and expression technologies to titrate FMRP in FXS and WT neurons. Our data demonstrate that restoration of greater than 5% of overall FMRP expression levels or greater than 20% FMRP-expressing neurons in a mosaic pattern is sufficient to normalize a FMRP-dependent, hyperactive phenotype in FXS iPSC-derived neurons.

Parotitis on Ultrasound: The Pomegranate Sign.

The differential diagnosis for facial swelling is broad and can be a diagnostic challenge in the pediatric emergency department. We describe the first pediatric case of acute parotitis with sialolithiasis where the diagnosis was facilitated by point-of-care ultrasound.

Fat-Dachsous signaling coordinates cartilage differentiation and polarity during craniofacial development.

Organogenesis requires coordinated regulation of cellular differentiation and morphogenesis. Cartilage cells in the vertebrate skeleton form polarized stacks, which drive the elongation and shaping of skeletal primordia. Here we show that an atypical cadherin, Fat3, and its partner Dachsous-2 (Dchs2), control polarized cell-cell intercalation of cartilage precursors during craniofacial development. In zebrafish embryos deficient in Fat3 or Dchs2, chondrocytes fail to stack and misregulate expression of sox9a. Similar morphogenetic defects occur in rerea/atr2a-/- mutants, and Fat3 binds REREa, consistent with a model in which Fat3, Dchs2 and REREa interact to control polarized cell-cell intercalation and simultaneously control differentiation through Sox9. Chimaeric analyses support such a model, and reveal long-range influences of all three factors, consistent with the activation of a secondary signal that regulates polarized cell-cell intercalation. This coordinates the spatial and temporal morphogenesis of chondrocytes to shape skeletal primordia and defects in these processes underlie human skeletal malformations. Similar links between cell polarity and differentiation mechanisms are also likely to control organ formation in other contexts.

Attitudes towards three ultrasound-guided vascular access techniques in a paediatric emergency department.

BACKGROUND: although nurses often place peripheral intravenous (IV) catheters, little is known about their perceptions regarding use of ultrasound guidance. AIM: the authors aimed to determine paediatric emergency department nurses' attitudes toward ultrasound-guided IV access techniques and assessed practice change after training. METHOD: In a cross-sectional study of nurses, they had didactic and hands-on practice sessions, using three short-axis ultrasound-guided IV access techniques on gel models. Outcomes included likability and ease of learning and performing the techniques. A 3-month follow-up questionnaire assessed attitudes and behavioural changes. RESULTS: 18 nurses were enrolled and 17 analysed. Participants liked all three techniques and thought they were easy to learn and perform. Eighty-two percent of the nurses used at least one technique clinically. The two-person self-guided technique was most preferred (65%) and used 3 months later (65%). CONCLUSIONS: nurses reported generally positive attitudes toward all three ultrasound-guided IV access techniques, but preferred the two-person self-guided technique. Owing to the small sample size, these results cannot be generalised and further research is needed.

Diagnosis of a Peritonsillar Abscess by Transcutaneous Point-of-Care Ultrasound in the Pediatric Emergency Department.

We report a case of a pediatric patient with an initial diagnosis of peritonsillar cellulitis made by otolaryngology. The findings from a subsequent transcutaneous point-of-care ultrasound by a pediatric emergency physician directly affected the decision to perform needle aspiration. Sonographic characteristics of a peritonsillar abscess may be helpful in the prompt diagnosis of peritonsillar abscess.

Scratching the surface: a review of skin and soft tissue infections in children.

PURPOSE OF REVIEW: We present data from recently conducted research on the diagnosis and management of skin and soft tissue infections (SSTIs) in children. RECENT FINDINGS: Current research in the area of SSTIs (cellulitis and abscess) has focused on the use of ultrasound, risk factors associated with bacteremia, antibiotic choice, and incision and drainage (I&D) practices. When clinical examination is equivocal at distinguishing abscess from cellulitis, ultrasound can aid in the diagnosis and alter management. Bacteremia is rare in immunocompetent children with uncomplicated SSTIs; blood cultures may be reserved for complicated cases and for those who are systemically ill. Despite the increased prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), I&D without antibiotics remains the first-line therapy for abscess. Antibiotics for uncomplicated cellulitis should target ß-hemolytic streptococci and methicillin-susceptible S. aureus (MSSA). There are significant variations in pain and sedation practices for I&D, with substantive evidence for the use of topical anesthetics. Wound packing after I&D may not confer significant benefit. SUMMARY: Evidence to aid in the diagnosis and management of SSTIs in children has emerged in recent years; however, larger prospective pediatric studies are needed.

Avoiding Computed Tomography Scans By Using Point-Of-Care Ultrasound When Evaluating Suspected Pediatric Renal Colic.

BACKGROUND: Although renal colic in children in the United States remains relatively uncommon compared to in adults, its incidence has nearly doubled from 1999 to 2008. Noncontrast computed tomography (CT) is the current standard for the evaluation of suspected renal colic, given its high sensitivity and specificity. However, the greater lifetime risk of radiation-induced cancer from CT in pediatric patients has led to efforts to minimize radiation exposure. Additionally, pediatric renal colic is often recurrent, which might require multiple imaging studies during their lifetime. Point-of-care ultrasound (POCUS) by emergency physicians avoids radiation, has a low marginal cost, can be performed concurrently with other management, and allows for earlier diagnosis and more rapid treatment of renal colic. Adult randomized controlled trial evidence supports using POCUS as the initial approach to imaging and management of suspected renal colic. However, there remain limited data on POCUS in children for renal colic. CASE REPORT: This is a case series where the sonographic findings of hydronephrosis, ureteral jets, "twinkling artifact," and the identification of urinary tract stones were used to evaluate adolescent and pediatric patients with renal colic. We report five cases of renal colic in adolescent and pediatric patients where urolithiasis was confirmed by using POCUS and irradiation by CT was avoided in all 5 patients. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: POCUS can provide information about the presence or absence of urinary tract stones as well as obstruction of the collecting system without the cost and radiation exposure of CT.

Point-of-care ultrasound for assisting in needle aspiration of spontaneous pneumothorax in the pediatric ED: a case series.

There is controversy regarding needle aspiration for primary spontaneous pneumothorax (PSP), with contradictory recommendations between the American College of Chest Physicians consensus statement (2001), which suggests that needle aspiration has little place in the management of PSP, and the British Thoracic Society guidelines (2010), which recommend that needle aspiration be attempted first for all cases of PSP where drainage is deemed necessary. Studies have shown that there is no significant difference between needle aspiration and tube thoracostomy with regard to safety, rates of immediate success, and early failure and has the advantages of decreasing pain and reducing rates of hospital admission and duration of hospital stay compared with tube thoracostomy. Point-of-care ultrasound (US) can facilitate needle aspiration by decreasing the risk of complications and detect pneumothorax resolution during or re-expansion after the procedure. This is a case series where the sonographic finding of the "lung point" on point-of-care US was used to facilitate needle aspiration to monitor pneumothorax resolution during or re-expansion after the procedure. We report 3 cases of PSP in adolescents presenting to the pediatric emergency department (ED), where needle aspiration was safely performed by using US to track the sonographic finding of the lung point. This technique allows the determination of pneumothorax resolution or re-expansion in real time. Point-of-care US may assist in the evaluation and management of spontaneous pneumothorax in the pediatric ED. Ultrasound-assisted needle aspiration may be a safe and less painful option for pediatric ED patients with PSP.

What matters most to people with metastatic uveal melanoma? A qualitative study to inform future measurement of health-related quality of life.

Metastatic uveal melanoma (mUM) is a rare cancer with poor prognosis, but novel treatments are emerging. Currently, there are no mUM-specific health-related quality of life (HRQL) questionnaires available for clinical research. We aimed to explore how mUM and its treatment affect HRQL and assess the content validity of existing questionnaires. Participants were patients with mUM and healthcare professionals involved in their care. Qualitative data were collected using semi-structured interviews and focus groups. Data collection and analysis used an integrative approach involving inductive questions/coding to elicit new concepts and deductive questions/coding based on domains of existing HRQL questionnaires. Initial interviews/focus groups focussed on HRQL questionnaires designed for patients with uveal melanoma or liver metastases. As new concepts were elicited, domains and items from other questionnaires were subsequently added. Seventeen patients and 16 clinicians participated. HRQL concerns assessed by uveal melanoma-specific questionnaires were largely resolved by the time of metastasis. The Functional Assessment of Cancer Therapy - Immunotherapy Module (FACT-ICM) adequately captured most immunotherapy-related side effects during initial treatment cycles. However, most patients emphasised emotional impacts over physical ones, focussing on the existential threat posed by disease amidst uncertainty about treatment accessibility and effectiveness. Patients were also concerned with treatment burden, including time commitment, travel, need for hospitalisation, and expenses. The relative importance of HRQL issues varied over time and across treatment modalities, with no single questionnaire being sufficient. Pending further development and psychometric testing, clinical researchers may need to take a modular approach to measuring the HRQL impacts of mUM.

Effects of Moderate- to High-Impact Exercise Training on Bone Structure Across the Lifespan: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Moderate- to high-impact exercise improves bone mineral density (BMD) across the lifespan, but its effects on bone structure, which predicts fracture independent of areal BMD, are unclear. This systematic review and meta-analysis investigated effects of impact exercise on volumetric BMD (vBMD) and bone structure. Four databases (PubMed, Embase, SPORTDiscus, Web of Science) were searched up to March 2022 for randomized controlled trials (RCTs) investigating the effects of impact exercise, with ground reaction forces equal to or greater than running, compared with sham or habitual activity, on bone vBMD and structure. Bone variables were measured by quantitative computed tomography or magnetic resonance imaging at the tibia, radius, lumbar spine, and femur. Percentage changes in bone variables were compared among groups using mean differences (MD) and 95% confidence intervals (CI) calculated via random effects meta-analyses. Subgroup analyses were performed in children/adolescents (<18 years), adults (18-50 years), postmenopausal women, and older men. Twenty-eight RCTs (n = 2985) were included. Across all studies, impact exercise improved trabecular vBMD at the distal tibia (MD = 0.54% [95% CI 0.17, 0.90%]), total vBMD at the proximal femur (3.11% [1.07, 5.14%]), and cortical thickness at the mid/proximal radius (1.78% [0.21, 3.36%]). There was no effect on vBMD and bone structure at the distal radius, femoral shaft, or lumbar spine across all studies or in any subgroup. In adults, impact exercise decreased mid/proximal tibia cortical vBMD (-0.20% [-0.24, -0.15%]). In postmenopausal women, impact exercise improved distal tibia trabecular vBMD (0.79% [0.32, 1.25%]). There was no effect on bone parameters in children/adolescents in overall analyses, and there were insufficient studies in older men to perform meta-analyses. Impact exercise may have beneficial effects on bone structure and vBMD at various skeletal sites, but additional high-quality RCTs in different age and sex subgroups are needed to identify optimal exercise protocols for improving bone health across the lifespan. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Reduced Peak Bone Mass in Young Adults With Low Motor Competence.

Although suboptimal bone health has been reported in children and adolescents with low motor competence (LMC), it is not known whether such deficits are present at the time of peak bone mass. We examined the impact of LMC on bone mineral density (BMD) in 1043 participants (484 females) from the Raine Cohort Study. Participants had motor competence assessed using the McCarron Assessment of Neuromuscular Development at 10, 14, and 17 years, and a whole-body dual-energy X-ray absorptiometry (DXA) scan at 20 years. Bone loading from physical activity was estimated from the International Physical Activity Questionnaire at the age of 17 years. The association between LMC and BMD was determined using general linear models that controlled for sex, age, body mass index, vitamin D status, and prior bone loading. Results indicated LMC status (present in 29.6% males and 21.9% females) was associated with a 1.8% to 2.6% decrease in BMD at all load-bearing bone sites. Assessment by sex showed that the association was mainly in males. Osteogenic potential of physical activity was associated with increased BMD dependent on sex and LMC status, with males with LMC showing a reduced effect from increasing bone loading. As such, although engagement in osteogenic physical activity is associated with BMD, other factors involved in physical activity, eg, diversity, movement quality, may also contribute to BMD differences based upon LMC status. The finding of lower peak bone mass for individuals with LMC may reflect a higher risk of osteoporosis, especially for males; however, further research is required. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Associations of body mass index, body fat percentage and sarcopenia components with bone health estimated by second-generation high-resolution peripheral quantitative computed tomography in older adults with obesity.

PURPOSE: To investigate associations between body mass index (BMI), body fat percentage, and components of sarcopenia (muscle mass and muscle strength/power), with bone microarchitecture measured by high-resolution peripheral computed tomography (HR-pQCT) in older adults with obesity. METHODS: Seventy-four adults aged ≥ 55 years with body fat percentage ≥ 30 % (men) or ≥40 % (women) were included. Fat mass, lean mass and total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD) were measured by dual-energy X-ray absorptiometry. Appendicular lean mass (ALM) was calculated as the sum of lean mass in the upper- and lower-limbs. BMI was calculated and participants completed physical function assessments including stair climb power test. Distal tibial bone microarchitecture was assessed using HR-pQCT. Linear regression (ß-coefficients and 95 % confidence intervals) analyses were performed with adjustment for confounders including age, sex, smoking status, vitamin D and self-reported moderate to vigorous physical activity. RESULTS: BMI and ALM/height2 were both positively associated with total hip, femoral neck and lumbar spine aBMD and trabecular bone volume fraction after adjusting for confounders (all p < 0.05). Body fat percentage was not associated with aBMD or any trabecular bone parameters but was negatively associated with cortical area (p < 0.05). Stair climb power (indicating better performance) was positively associated with cortical area and negatively associated with bone failure load (both p < 0.05). CONCLUSION: Higher BMI, ALM/height2 and muscle power were associated with more favourable bone microarchitecture, but higher body fat percentage was negatively associated with cortical bone area. These findings suggest that high BMI may be protective for fractures and that this might be attributable to higher muscle mass and/or forces, while higher relative body fat is not associated with better bone health in older adults with obesity.

In vivo selection in non-human primates identifies superior AAV capsids for on-target CSF delivery to spinal cord.

Systemic administration of adeno-associated virus (AAV) vectors for spinal cord gene therapy has challenges including toxicity at high doses and pre-existing immunity that reduces efficacy. Intrathecal delivery of AAV vectors into the cerebral spinal fluid (CSF) can avoid many of the issues of systemic delivery, although achieving broad distribution of the vector and transgene expression throughout the spinal cord is challenging and vector entry to the periphery occurs, sometimes initiating hepatotoxicity. Here we performed two rounds of in vivo biopanning in non-human primates (NHPs) with an AAV9 peptide display library injected intrathecally and performed insert sequencing on DNA isolated from either whole tissue (conventional selection), isolated nuclei, or nuclei from transgene-expressing cells. A subsequent barcoded pool of candidates and AAV9 was compared at the DNA (biodistribution) and RNA (expression) level in spinal cord and liver of intrathecally injected NHPs. Most of the candidates displayed enhanced biodistribution compared to AAV9 at all levels of spinal cord ranging from 2 to 265-fold. Nuclear isolation or expression-based selection yielded 4 of 7 candidate capsids with enhanced transgene expression in spinal cord (up to 2.4-fold), while no capsid obtained by conventional selection achieved that level. Furthermore, several capsids displayed lower biodistribution to the liver of up to 1,250-fold, compared to AAV9, providing a remarkable on target/off target biodistribution ratio. These capsids may have potential for gene therapy programs directed at the spinal cord and the selection method described here should be useful in clinically relevant large animal models.

An Engineered Adeno-Associated Virus Capsid Mediates Efficient Transduction of Pericytes and Smooth Muscle Cells of the Brain Vasculature.

Neurodegeneration and cerebrovascular disease share an underlying microvascular dysfunction that may be remedied by selective transgene delivery. To date, limited options exist in which cellular components of the brain vasculature can be effectively targeted by viral vector therapeutics. In this study, we characterize the first engineered adeno-associated virus (AAV) capsid mediating high transduction of cerebral vascular pericytes and smooth muscle cells (SMCs). We performed two rounds of in vivo selection with an AAV capsid scaffold displaying a heptamer peptide library to isolate capsids that traffic to the brain after intravenous delivery. One identified capsid, termed AAV-PR, demonstrated high transduction of the brain vasculature, in contrast to the parental capsid, AAV9, which transduces mainly neurons and astrocytes. Further analysis using tissue clearing, volumetric rendering, and colocalization revealed that AAV-PR enabled high transduction of cerebral pericytes located on small-caliber vessels and SMCs in the larger arterioles and penetrating pial arteries. Analysis of tissues in the periphery indicated that AAV-PR also transduced SMCs in large vessels associated with the systemic vasculature. AAV-PR was also able to transduce primary human brain pericytes with higher efficiency than AAV9. Compared with previously published AAV capsids tropisms, AAV-PR represents the first capsid to allow for effective transduction of brain pericytes and SMCs and offers the possibility of genetically modulating these cell types in the context of neurodegeneration and other neurological diseases.

WT1-dependent sulfatase expression maintains the normal glomerular filtration barrier.

Paracrine signaling between podocytes and glomerular endothelial cells through vascular endothelial growth factor A (VEGFA) maintains a functional glomerular filtration barrier. Heparan sulfate proteoglycans (HSPGs), located on the cell surface or in the extracellular matrix, bind signaling molecules such as VEGFA and affect their local concentrations, but whether modulation of these moieties promotes normal crosstalk between podocytes and endothelial cells is unknown. Here, we found that the transcription factor Wilms' Tumor 1 (WT1) modulates VEGFA and FGF2 signaling by increasing the expression of the 6-O-endosulfatases Sulf1 and Sulf2, which remodel the heparan sulfate 6-O-sulfation pattern in the extracellular matrix. Mice deficient in both Sulf1 and Sulf2 developed age-dependent proteinuria as a result of ultrastructural abnormalities in podocytes and endothelial cells, a phenotype similar to that observed in children with WT1 mutations and in Wt1(+/-) mice. These kidney defects associated with a decreased distribution of VEGFA in the glomerular basement membrane and on endothelial cells. Collectively, these data suggest that WT1-dependent sulfatase expression plays a critical role in maintaining the glomerular filtration barrier by modulating the bioavailability of growth factors, thereby promoting normal crosstalk between podocytes and endothelial cells.

Physical activity estimated by osteogenic potential and energy expenditure has differing associations with bone mass in young adults: the raine study.

Ground impacts during physical activity may be important for peak bone mass. We found differences in how energy expenditure and impact scores estimated from a physical activity questionnaire related to bone health in young adults. Using both estimate types can improve our understanding of the skeletal benefits of physical activity. PURPOSE: It is unclear whether mechanical loading during physical activity, estimated from physical activity questionnaires which assess metabolic equivalents of task (METs), is associated with skeletal health. This longitudinal study investigated how physical activity loading scores, assessed at ages 17 and 20 years, (a) compares with physical activity measured in METs, and (b) is associated with bone mass at age 20 years. METHODS: A total of 826 participants from the Raine Study Gen2 were assessed for physical activity energy expenditure via the International Physical Activity Questionnaire (IPAQ) at age 17 and 20 years. Loading scores (the product of peak force and application rate) per week were subsequently estimated from the IPAQ. Whole-body and appendicular bone mineral density (BMD) at age 20 years were assessed by dual-energy X-ray absorptiometry. RESULTS: Bland-Altman minimal detectable difference for physical activity Z- scores at age 17 and 20 years were 1.59 standard deviations (SDs) and 1.33 SDs, respectively, greater than the a priori minimal clinically important change of 0.5 SDs. Loading score, but not IPAQ score, had significant positive associations with whole-body and leg BMD after adjustment for covariates (ß = 0.008 and 0.012 g/cm2, respectively, for age 17 and 20 years loading scores). IPAQ score at age 20 years, but not loading score, had a significant positive association with arm BMD (ß = 0.007 g/cm2). CONCLUSION: This study revealed disagreement in associations of self-reported METs and loading score estimates with bone health in young adults. Coupling traditional energy expenditure questionnaire outcomes with bone-loading estimates may improve understanding of the location-specific skeletal benefits of physical activity in young adults.