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| 2. |
- 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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| 3. |
- Buttazzoni, Christian, et al.
(författare)
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Preterm Children Born Small for Gestational Age are at Risk for Low Adult Bone Mass.
- 2016
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 1432-0827 .- 0171-967X. ; 98:2, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- Cross-sectional studies suggest that premature birth and low birth weight may both be associated with low peak bone mass. We followed bone traits in preterm individuals and controls for 27 years and examined the effects of birth weight relative to gestational age [stratified as small for gestational age (SGA) or appropriate for gestational (AGA)] on adult bone mineral density (BMD). We measured distal forearm BMC (g/cm) and BMD (g/cm(2)) with single-photon absorptiometry (SPA) in 46 preterm children (31 AGA and 15 SGA) at mean age 10.1 years (range 4-16) and in 84 healthy age-matched children. The measurements were repeated 27 years later with the same SPA apparatus but then also with dual energy absorptiometry and peripheral computed tomography (pQCT). Preterm individuals were shorter (p = 0.03) in adulthood than controls. Preterm AGA individuals had similar BMC and BMD height-adjusted Z-scores in adulthood compared to controls. Preterm SGA individuals had lower distal forearm BMC and BMD height-adjusted Z-scores in adulthood than both controls and preterm AGA individuals. Preterm SGA individuals had lower gain from childhood to adulthood in distal forearm BMC height-adjusted Z-scores than controls (p = 0.03). The deficits in preterm SGA individuals in adulthood were also captured by DEXA in height-adjusted femoral neck (FN) BMC Z-score and height-adjusted FN BMD Z-score and by pQCT in tibial cross-sectional area (CSA) Z-score and stress strain index (SSI) Z-score, where all measurements were lower than controls (all p values <0.05). Preterm SGA individuals are at increased risk of reaching low adult bone mass, at least partly due to a deficit in the accrual of bone mineral during growth. In our cohort, we were unable to find a similar risk in preterm AGA individuals.
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| 5. |
- Døvling Kaspersen, Jørn, et al.
(författare)
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Small-Angle X-ray Scattering Demonstrates Similar Nanostructure in Cortical Bone from Young Adult Animals of Different Species.
- 2016
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 1432-0827 .- 0171-967X.
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Tidskriftsartikel (refereegranskat)abstract
- Despite the vast amount of studies focusing on bone nanostructure that have been performed for several decades, doubts regarding the detailed structure of the constituting hydroxyapatite crystal still exist. Different experimental techniques report somewhat different sizes and locations, possibly due to different requirements for the sample preparation. In this study, small- and wide-angle X-ray scattering is used to investigate the nanostructure of femur samples from young adult ovine, bovine, porcine, and murine cortical bone, including three different orthogonal directions relative to the long axis of the bone. The radially averaged scattering from all samples reveals a remarkable similarity in the entire q range, which indicates that the nanostructure is essentially the same in all species. Small differences in the data from different directions confirm that the crystals are elongated in the [001] direction and that this direction is parallel to the long axis of the bone. A model consisting of thin plates is successfully employed to describe the scattering and extract the plate thicknesses, which are found to be in the range of 20-40 Å for most samples but 40-60 Å for the cow samples. It is demonstrated that the mineral plates have a large degree of polydispersity in plate thickness. Additionally, and equally importantly, the scattering data and the model are critically evaluated in terms of model uncertainties and overall information content.
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| 6. |
- Egund, Lisa, et al.
(författare)
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High Prevalence of Osteoporosis in Men with Distal Radius Fracture : A Cross-Sectional Study of 233 Men
- 2016
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 99:3, s. 250-258
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Tidskriftsartikel (refereegranskat)abstract
- Distal radius fracture is an early indicator of osteoporosis, yet little is known about men with this fracture and osteoporosis prevalence. The purpose of this cross-sectional, controlled study was to evaluate bone mineral density (BMD) in men, from working age to the elderly, with distal radius fracture. Recruitment was as follows: men who fractured during 1999–2000 were evaluated retrospectively in 2003 and men who fractured during 2003–2007 were followed prospectively for one year post-fracture. A total of 233 patients, response rate 40 %, were enrolled and compared with 643 controls. Fractures from all degrees of trauma were included. BMD was measured at femoral neck, total hip, and lumbar spine. Mean age at fracture was 52 years (21–88 years). Men aged 40–64 years had 5.4–6.7 % lower BMD at all sites compared to controls (p = 0.001) and in >65 years BMD was lower by 10.7–13.8 % (p <0.001), while not significant at 65 years: 23.3 vs 8.3 %) BMD did not differ with trauma level. Already from age 40, men with a distal radius fracture had lower BMD, the difference becoming more pronounced with increasing age. Also, the prevalence of osteoporosis was higher, surprisingly even in the youngest age group.
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| 8. |
- Fritz, Jesper, et al.
(författare)
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Influence of a School-based Physical Activity Intervention on Cortical Bone Mass Distribution : A 7-year Intervention Study
- 2016
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 99:5, s. 443-453
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Tidskriftsartikel (refereegranskat)abstract
- Cortical bone mass and density varies across a bones length and cross section, and may be influenced by physical activity. This study evaluated the long-term effects of a pediatric school-based physical activity intervention on tibial cortical bone mass distribution. A total of 170 children (72 girls and 98 boys) from one school were provided with 200 min of physical education per week. Three other schools (44 girls and 47 boys) continued with the standard 60 min per week. Tibial total and cortical area, cortical density, polar stress–strain index (SSI), and the mass and density distribution around the center of mass (polar distribution, mg) and through the bones cortex (radial distribution subdivided into endo-, mid-, and pericortical volumetric BMD: mg/cm3) at three sites (14, 38, and 66 %) were assessed using peripheral quantitative computed tomography after 7 years. Girls in the intervention group had 2.5 % greater cortical thickness and 6.9 % greater SSI at the 66 % tibia, which was accompanied by significantly greater pericortical volumetric BMD compared to controls (all P <0.05). Region-specific differences in cortical mass were also detected in the anterior, medial, and lateral sectors at the 38 and 66 % tibial sites. There were no group differences at the 14 % tibia site in girls, and no group differences in any of the bone parameters in boys. Additional school-based physical education over seven years was associated with greater tibial structure, strength, and region-specific adaptations in cortical bone mass and density distribution in girls, but not in boys.
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| 9. |
- Halling Linder, Cecilia, et al.
(författare)
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Bone Alkaline Phosphatase and Tartrate-Resistant Acid Phosphatase: Potential Co-regulators of Bone Mineralization
- 2017
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Ingår i: Calcified Tissue International. - : SPRINGER. - 0171-967X .- 1432-0827. ; 101:1, s. 92-101
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorylated osteopontin (OPN) inhibits hydroxyapatite crystal formation and growth, and bone alkaline phosphatase (BALP) promotes extracellular mineralization via the release of inorganic phosphate from the mineralization inhibitor inorganic pyrophosphate (PPi). Tartrate-resistant acid phosphatase (TRAP), produced by osteoclasts, osteoblasts, and osteocytes, exhibits potent phosphatase activity towards OPN; however, its potential capacity as a regulator of mineralization has not previously been addressed. We compared the efficiency of BALP and TRAP towards the endogenous substrates for BALP, i.e., PPi and pyridoxal 5-phosphate (PLP), and their impact on mineralization in vitro via dephosphorylation of bovine milk OPN. TRAP showed higher phosphatase activity towards phosphorylated OPN and PPi compared to BALP, whereas the activity of TRAP and BALP towards PLP was comparable. Bovine milk OPN could be completely dephosphorylated by TRAP, liberating all its 28 phosphates, whereas BALP dephosphorylated at most 10 phosphates. OPN, dephosphorylated by either BALP or TRAP, showed a partially or completely attenuated phosphorylation-dependent inhibitory capacity, respectively, compared to native OPN on the formation of mineralized nodules. Thus, there are phosphorylations in OPN important for inhibition of mineralization that are removed by TRAP but not by BALP. In conclusion, our data indicate that both BALP and TRAP can alleviate the inhibitory effect of OPN on mineralization, suggesting a potential role for TRAP in skeletal mineralization. Further studies are warranted to explore the possible physiological relevance of TRAP in bone mineralization.
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| 10. |
- Halling Linder, Cecilia, et al.
(författare)
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Glycation Contributes to Interaction Between Human Bone Alkaline Phosphatase and Collagen Type I
- 2016
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Ingår i: Calcified Tissue International. - : Springer-Verlag New York. - 0171-967X .- 1432-0827. ; 98:3, s. 284-293
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Tidskriftsartikel (refereegranskat)abstract
- Bone is a biological composite material comprised primarily of collagen type I and mineral crystals of calcium and phosphate in the form of hydroxyapatite (HA), which together provide its mechanical properties. Bone alkaline phosphatase (ALP), produced by osteoblasts, plays a pivotal role in the mineralization process. Affinity contacts between collagen, mainly type II, and the crown domain of various ALP isozymes were reported in a few in vitro studies in the 1980s and 1990s, but have not attracted much attention since, although such interactions may have important implications for the bone mineralization process. The objective of this study was to investigate the binding properties of human collagen type I to human bone ALP, including the two bone ALP isoforms B1 and B2. ALP from human liver, human placenta and E. coli were also studied. A surface plasmon resonance-based analysis, supported by electrophoresis and blotting, showed that bone ALP binds stronger to collagen type I in comparison with ALPs expressed in non-mineralizing tissues. Further, the B2 isoform binds significantly stronger to collagen type I in comparison with the B1 isoform. Human bone and liver ALP (with identical amino acid composition) displayed pronounced differences in binding, revealing that post-translational glycosylation properties govern these interactions to a large extent. In conclusion, this study presents the first evidence that glycosylation differences in human ALPs are of crucial importance for protein–protein interactions with collagen type I, although the presence of the ALP crown domain may also be necessary. Different binding affinities among the bone ALP isoforms may influence the mineral-collagen interface, mineralization kinetics, and degree of bone matrix mineralization, which are important factors determining the material properties of bone.
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