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| 2. |
- Alijagic, Andi, 1992-, et al.
(författare)
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Particle Safety Assessment in Additive Manufacturing : From Exposure Risks to Advanced Toxicology Testing.
- 2022
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Ingår i: Frontiers in Toxicology. - : Frontiers Media S.A.. - 2673-3080. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) or industrial three-dimensional (3D) printing drives a new spectrum of design and production possibilities; pushing the boundaries both in the application by production of sophisticated products as well as the development of next-generation materials. AM technologies apply a diversity of feedstocks, including plastic, metallic, and ceramic particle powders with distinct size, shape, and surface chemistry. In addition, powders are often reused, which may change the particles' physicochemical properties and by that alter their toxic potential. The AM production technology commonly relies on a laser or electron beam to selectively melt or sinter particle powders. Large energy input on feedstock powders generates several byproducts, including varying amounts of virgin microparticles, nanoparticles, spatter, and volatile chemicals that are emitted in the working environment; throughout the production and processing phases. The micro and nanoscale size may enable particles to interact with and to cross biological barriers, which could, in turn, give rise to unexpected adverse outcomes, including inflammation, oxidative stress, activation of signaling pathways, genotoxicity, and carcinogenicity. Another important aspect of AM-associated risks is emission/leakage of mono- and oligomers due to polymer breakdown and high temperature transformation of chemicals from polymeric particles, both during production, use, and in vivo, including in target cells. These chemicals are potential inducers of direct toxicity, genotoxicity, and endocrine disruption. Nevertheless, understanding whether AM particle powders and their byproducts may exert adverse effects in humans is largely lacking and urges comprehensive safety assessment across the entire AM lifecycle-spanning from virgin and reused to airborne particles. Therefore, this review will detail: 1) brief overview of the AM feedstock powders, impact of reuse on particle physicochemical properties, main exposure pathways and protective measures in AM industry, 2) role of particle biological identity and key toxicological endpoints in the particle safety assessment, and 3) next-generation toxicology approaches in nanosafety for safety assessment in AM. Altogether, the proposed testing approach will enable a deeper understanding of existing and emerging particle and chemical safety challenges and provide a strategy for the development of cutting-edge methodologies for hazard identification and risk assessment in the AM industry.
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- Buttazzoni, Christian, et al.
(författare)
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A Pediatric Bone Mass Scan has Poor Ability to Predict Peak Bone Mass: An 11-Year Prospective Study in 121 Children.
- 2015
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 1432-0827 .- 0171-967X. ; 96:5, s. 379-388
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Tidskriftsartikel (refereegranskat)abstract
- This 11-year prospective longitudinal study examined how a pre-pubertal pediatric bone mass scan predicts peak bone mass. We measured bone mineral content (BMC; g), bone mineral density (BMD; g/cm(2)), and bone area (cm(2)) in femoral neck, total body and lumbar spine by dual-energy X-ray absorptiometry in a population-based cohort including 65 boys and 56 girls. At baseline all participants were pre-pubertal with a mean age of 8 years (range 6-9), they were re-measured at a mean 11 years (range 10-12) later. The participants were then mean 19 years (range 18-19), an age range that corresponds to peak bone mass in femoral neck in our population. We calculated individual BMC, BMD, and bone size Z scores, using all participants at each measurement as reference and evaluated correlations between the two measurements. Individual Z scores were also stratified in quartiles to register movements between quartiles from pre-pubertal age to peak bone mass. The correlation coefficients (r) between pre-pubertal and young adulthood measurements for femoral neck BMC, BMD, and bone area varied between 0.37 and 0.65. The reached BMC value at age 8 years explained 42 % of the variance in the BMC peak value; the corresponding values for BMD were 31 % and bone area 14 %. Among the participants with femoral neck BMD in the lowest childhood quartile, 52 % had left this quartile at peak bone mass. A pediatric bone scan with a femoral neck BMD value in the lowest quartile had a sensitivity of 47 % [95 % confidence interval (CI) 28, 66] and a specificity of 82 % (95 % CI 72, 89) to identify individuals who would remain in the lowest quartile at peak bone mass. The pre-pubertal femoral neck BMD explained only 31 % of the variance in femoral neck peak bone mass. A pre-pubertal BMD scan in a population-based sample has poor ability to predict individuals who are at risk of low peak bone mass.
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- Cöster, Marcus E., et al.
(författare)
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Effects of an 8-year childhood physical activity intervention on musculoskeletal gains and fracture risk
- 2016
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Ingår i: Bone. - : Elsevier BV. - 8756-3282. ; 93, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Background Physical activity (PA) in childhood is associated with musculoskeletal benefits while the effect on fracture risk is yet to be determined. The aim of this study was to evaluate whether extension of a PA intervention leads to improvement in musculoskeletal traits with an accompanied reduced fracture risk. We hypothesized that the PA program would have beneficial effects in both sexes, but more so in girls since they tend to be less physically active than boys during this time frame. Methods In one elementary school we increased physical education (PE) from 60 to 200 min per school week and followed 65 girls and 93 boys from a mean age of 7 years until a mean age of 15 years. Thirty-nine girls and 37 boys in three other schools continued with 60 min of PE per week during the same years and served as controls. We measured bone mineral content (BMC), areal bone mineral density (aBMD), and bone area annually with dual energy X-ray absorptiometry, and leg muscle strength with a computerized dynamometer. In 3534 children within the same PE program (1339 in the intervention and 2195 in the control group) we registered incident fractures during the 8-year study period and estimated annual sex-specific fracture incidence rate ratios (IRRs). Results Girls in the intervention group annually gained more total body less head aBMD, spine aBMD (p < 0.01), femoral neck BMC (p < 0.05), lumbar vertebrae size (p < 0.05), and knee flexion strength (p < 0.05) than girls in the control cohort. In boys we found no group differences. There was an inverse correlation between number of years with extra PE and the annual IRR of sustaining fractures in both girls (r = − 0.90 (95% CI − 0.98 to − 0.51); p < 0.001) and boys (r = − 0.74 (95% CI − 0.94 to − 0.02); p < 0.05). Conclusion In this 8-year pediatric school-based moderate exercise intervention program there is an inverse correlation in both sexes between annual IRR and each additional year of extra PA. A sub-cohort of girls in the intervention group had greater gains in bone mass, bone size, and muscle strength, which could possibly explain the inverse correlation between years within the PA program and fracture risk, while in boys the reason for the inverse correlation remains unknown. It should be noted that differences in unreported factors such as skeletal maturity status, diet, and spare time PA could confound our inferences. That is, true causality cannot be stated.
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| 5. |
- Cöster, Marcus E., et al.
(författare)
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How does a physical activity programme in elementary school affect fracture risk? : A prospective controlled intervention study in Malmo, Sweden
- 2017
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Recent evidence from the 7-year followup of the Pediatric Osteoporosis Prevention (POP) study indicates an inverse correlation between years of participation in a physical activity (PA) intervention and fracture risk in children. However, we could not see a statistically significant reduction in fracture risk, which urged for an extension of the intervention. Setting: The study was conducted in 4 neighbouring elementary schools, where 1 school functioned as intervention school. Participants: We included all children who began first grade in these 4 schools between 1998 and 2012. This resulted in 1339 children in the intervention group and 2195 children in the control group, all aged 6-8 years at the state of the study. Intervention: We launched an 8-year intervention programme with 40 min of moderate PA per school day, while the controls continued with the Swedish national standard of 60 min of PA per week. Primary outcome measure: We used the regional radiographic archive to register objectively verified fractures and we estimated annual fracture incidences and incidence rate ratios (IRRs). Results: During the first year after initiation of the intervention, the fracture IRR was 1.65 (1.05 to 2.08) (mean 95% CI). For each year of the study, the fracture incidence rate in the control group compared with the intervention group increased by 15.7% (5.6% to 26.8%) (mean 95% CI). After 8 years, the IRR of fractures was 52% lower in the intervention group than in the control group (IRR 0.48 (0.25 to 0.91) (mean 95% CI))]. Conclusions: Introduction of the school-based intervention programme is associated with a higher fracture risk in the intervention group during the first year followed by a gradual reduction, so that during the eighth year, the fracture risk was lower in the intervention group.
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| 6. |
- Detter, Fredrik, et al.
(författare)
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A 3-year school-based exercise intervention improves muscle strength - a prospective controlled population-based study in 223 children
- 2014
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Ingår i: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Intense physical activity (PA) improves muscle strength in children, but it remains uncertain whether moderately intense PA in a population-based cohort of children confers these benefits. Methods: We included children aged 6-9 years in four schools where the intervention school increased the school curriculum of PA from 60 minutes/week to 40 minutes/school day while the control schools continued with 60 minutes/week for three years. We measured muscle strength, as isokinetic Peak Torque (PT) (Nm) of the knee flexors in the right leg at speeds of 60 degrees/second and 180 degrees/second, at baseline and at follow-up, in 47 girls and 76 boys in the intervention group and 46 girls and 54 boys in the control group and then calculated annual changes in muscle strength. Data are provided as means with 95% confidence intervals. Results: Girls in the intervention group had 1.0 Nm (0.13, 1.9) and boys 1.9 Nm (0.9, 2.9) greater annual gain in knee flexor PT at 60 degrees/second, than girls and boys in the control group. Boys in the intervention group also had 1.5 Nm (0.5, 2.5) greater annual gain in knee flexors PT at 180 degrees/second than boys in the control group. Conclusion: A 3-year moderately intense PA intervention program within the school curriculum enhances muscle strength in both girls and boys.
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| 7. |
- FRITZ, JESPER, et al.
(författare)
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A seven-year physical activity intervention for children increased gains in bone mass and muscle strength
- 2016
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Ingår i: Acta Pædiatrica. - : Wiley. - 0803-5253. ; 105:10, s. 1216-1224
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Tidskriftsartikel (refereegranskat)abstract
- Aim: This study evaluated the musculoskeletal effects of increased physical activity on children, starting at six to nine years of age. Methods: In one school we increased the physical education of 72 girls and 100 boys to 200 minutes per week over seven years. In three other schools, 45 girls and 47 boys continued to receive 60 minutes per week. We measured areal bone mineral density (aBMD) with dual energy X-ray absorptiometry and muscle strength with computerised dynamometer at baseline and after seven years and tibial cortical thickness with peripheral quantitative computed tomography after seven years. Results: Girls in the intervention group gained 0.04 g/cm2 (0.01-0.08) more total spine aBMD (p <0.05) and 6.2Nm (1.6, 10.7) more knee flexion strength (p <0.01) than control group girls and had a 0.1 mm (0.0, 0.3) higher tibial cortical thickness at follow-up (p <0.05). Boys in the intervention group gained 7.3Nm (0.4, 14.2) more knee extension strength (p <0.05) and 7.4Nm (2.3, 12.4) more knee flexion strength (p <0.01) than the control group boys, but their aBMD was no higher than the control group. Conclusion: A seven-year, population-based moderately intense exercise intervention enhanced gains in spine bone mass in girls and knee muscle strength in both genders.
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| 8. |
- Karlsson, Magnus, et al.
(författare)
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Daglig skolidrott ger ökad benmassa och successivt minskad frakturrisk
- 2019
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Ingår i: Läkartidningen. - 0023-7205. ; 116:12
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Tidskriftsartikel (refereegranskat)abstract
- In the Bunkeflo project, one elementary school increased duration of school physical activity (PA) to 200 minutes/week while 3 control schools continued with 60 minutes/week throughout the nine elementary school years. We then registered fractures in 3534 children, and evaluated the duration of PA, bone mass and muscle strength in a subsample (n=140) during the intervention and 3 years after. The PA intervention was associated with higher duration of PA both during and 3 years after the intervention. With each year of intervention, the fracture incidence rate ratio (IRR) declined in the intervention children so that it was 0.48 (95% CI 0.25, 0.91) the eighth year of intervention. These findings were accompanied by beneficial gain in musculoskeletal traits in both intervention girls and boys (p<0.05). Nine years of daily school-based PA is associated with a progressive reduction in fracture risk, accompanied by beneficial musculoskeletal gains and a more physically active lifestyle.
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| 10. |
- Alwis, Gayani, et al.
(författare)
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A 2-year school-based exercise programme in pre-pubertal boys induces skeletal benefits in lumbar spine.
- 2008
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Ingår i: Acta Pædiatrica. - : Wiley. - 1651-2227 .- 0803-5253. ; 97, s. 1564-1571
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to evaluate if a general school-based exercise intervention programme in pre-pubertal boys would render site-specific benefits in bone mineral accrual and gain in femoral neck structure. Methods: Eighty boys aged 7-9 years were included in a curriculum-based exercise intervention programme comprising 40 min of general physical activity per school day (200 min/week) for 2 years. Fifty-seven age-matched boys, assigned to the general Swedish school curriculum of 60 min/week, served as controls. Bone mineral content was measured with dual X-ray absorptiometry of the total body, the third lumbar vertebra and hip. Specific software, the hip structural analyses, evaluated the structural properties of the femoral neck. Annual changes were compared. The level of physical activity was estimated through questionnaires and accelerometers. Results: The mean annual bone mineral content gain in third lumbar vertebra was 3.0 percentage points (p < 0.01) and in width 1.3 percentage points (p < 0.01) greater in the intervention than in the control group. The weekly duration of exercise estimated through the questionnaire correlated with gain in bone mineral content in third lumbar vertebra (r = 0.25, p = 0.005) and vertebra width (r = 0.20, p = 0.02). Conclusion: A school-based exercise intervention programme in pre-pubertal boys enhances the skeletal benefits at lumbar spine.
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