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Klaus Klaushofer - One of the best experts on this subject based on the ideXlab platform.
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effects of sodium fluoride and alendronate on the bone mineral in minipigs a small angle x ray scattering and Backscattered Electron imaging study
Journal of Bone and Mineral Research, 2009Co-Authors: Peter Fratzl, Peter Roschger, Garry Rodan, Sabine Schreiber, Mariehelene Lafage, Klaus KlaushoferAbstract:Sodium fluoride (NaF), which stimulates bone formation, and bisphosphonates, which reduce bone resorption, are both used in the treatment of osteoporosis, and are binding to bone mineral. In this study, using small-angle X-ray scattering and Backscattered Electron imaging, we analyzed the bone mineral in the vertebrae of minipigs treated with fluoride, with the bisphosphonate alendronate (ALN), or with vehicle. All specimens were investigated blindly. A slight increase in the average thickness of the mineral crystals as well as changes in the structure of the mineral/collagen composite were found in the case of fluoride-treated animals. No differences were found between ALN-treated animals and controls. The changes produced by fluoride are in the same direction as seen in bones from patients treated with NaF, albeit much smaller. They also correlate quantitatively with the reduction in biomechanical properties of bone in fluoride-treated minipigs found in an earlier study with the same animals. These findings suggest that small changes in the structure of the mineral/collagen composite in bone may considerably affect its biomechanical properties. It also emphasizes the delicate balance between the increase of bone mass and deterioration of bone material properties for the effect of fluoride on the biomechanical properties of bone.
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Combination of Nanoindentation and Quantitative Backscattered Electron Imaging Revealed Altered Bone Material Properties Associated with Femoral Neck Fragility
Calcified Tissue International, 2009Co-Authors: N. Fratzl-zelman, Peter Roschger, Klaus Klaushofer, A. Gourrier, M. Weber, B. M. Misof, N. Loveridge, J. Reeve, Peter FratzlAbstract:Osteoporotic fragility fractures were hypothesized to be related to changes in bone material properties and not solely to reduction in bone mass. We studied cortical bone from the superior and inferior sectors of whole femoral neck sections from five female osteoporotic hip fracture cases (74–92 years) and five non fractured controls (75–88 years). The typical calcium content (Ca Peak ) and the mineral particle thickness parameter (T) were mapped in large areas of the superior and inferior regions using quantitative Backscattered Electron imaging (qBEI) and scanning small-angle X-ray scattering, respectively. Additionally, indentation modulus (E) and hardness (H) (determined by nanoindentation) were compared at the local level to the mineral content (Ca Ind) at the indent positions (obtained from qBEI). Ca Peak (-2.2%, P = 0.002), Ca Ind (-1.8%, P = 0.048), E (-5.6%, P = 0.040), and H (-6.0%, P = 0.016)were significantly lower for the superior compared to the inferior region. Interestingly, Ca Peak as well as Ca Ind were also lower (-2.6%, P = 0.006, and –3.7%, P = 0.002, respectively) in fracture cases compared to controls,while E and H did not show any significant reduction. T values were in the normal range, independent of region (P = 0.181) or fracture status(P = 0.551). In conclusion, it appears that the observed femoral neck fragility is associated with a reduced mineral content, which was not accompanied by a reduction in stiffness and hardness of the bone material. This pilot study suggests that a stiffening process in the organic matrix component contributes to bone fragility independently of mineral content.
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new observations on bone quality in mild primary hyperparathyroidism as determined by quantitative Backscattered Electron imaging
Journal of Bone and Mineral Research, 2007Co-Authors: Peter Roschger, David W Dempster, Hua Zhou, Eleftherios P Paschalis, Shonni J Silverberg, Elisabeth Shane, John P Bilezikian, Klaus KlaushoferAbstract:Bone mineralization density distribution, an important aspect of bone material quality, was determined in mild primary hyperparathyroidism using quantitative Backscattered Electron imaging. A strong correlation between bone turnover status and degree and heterogeneity of mineralization was found. Further studies are needed before we can draw conclusions about fracture risk in this disorder. Introduction: Mild primary hyperparathyroidism (PHPT) is best characterized by asymptomatic hypercalcemia, most commonly in the absence of classical signs and symptoms. Hence, there is need to characterize this disorder with particular attention to the skeleton. Materials and Methods: We analyzed bone mineralization density distribution (BMDD) in iliac crest bone biopsies from patients with PHPT in 51 subjects (16 men, 28–68 years of age; 35 women, 26–74 years of age) by quantitative Backscattered Electron imaging (qBEI). The BMDD variables quantified are as follows: CaMEAN, the weighted mean calcium concentration; CaPEAK, the most frequent Ca concentration; CaWIDTH, the width of the distribution, a measure of the mineralization homogeneity; CaLOW, the percentage of bone area that is mineralized below the fifth percentile in the reference range. The results were compared with a reference range that we have previously established. Results: The greatest differences were found in CaWIDTH (+15.7%, p < 0.0001) and CaLOW (+44.7%, p < 0001), both of which were significantly higher in PHPT than control. CaMEAN was significantly lower (−2.5%, p < 0.0001) in PHPT compared with controls. These differences were reversed in seven patients who underwent parathyroidectomy. CaMEAN and CaPEAK variables were negatively, whereas CaWIDTH and CaLOW were positively, correlated with dynamic variables of bone formation: mineralizing surface and bone formation rate as determined by histomorphometry. (r = ±0.3–0.8; p = 0.05–0.0001). These results, which represent the first BMDD measurements in mild PHPT using qBEI, show a reduction in the average mineralization density and an increase in the heterogeneity of the degree of mineralization. These changes correlate significantly with the bone turnover rate. Conclusions: The results are consistent with our previous observations of increased bone turnover in this disease, and consequently, reduced mean age of bone tissue. Reduced mineralization density in patients with PHPT would be expected to reduce the stiffness of bone tissue. These observations are relevant to considerations of fracture risk in PHPT.
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:Abstract The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance—instrumental stability and interassay variance—reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30–85 years) BMDD measurements were conducted. The patients’ medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance-instrumental stability and interassay variance-reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30-85 years) BMDD measurements were conducted. The patients' medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were <0.3%, <0.4%, <0.9%, and <2.6% of the mean for the intraassay, interassay, intraindividual, and interindividual variations, respectively. In addition, a mean BMDD histogram for transiliac bone specimens was calculated from the 20 aforementioned individuals. The method used allows detection of the degree of mineralization independently from the actual bone volume, a result that seems to be of special interest in the assessment of the effect of treatments for osteoporosis. The power of this technique is demonstrated by using bone from a patient with a metabolic bone disease. In this case of osteomalacia due to celiac disease, the mean calcium concentration in the bone matrix was reduced by 19.3% as compared with normal.
N R Buenfeld - One of the best experts on this subject based on the ideXlab platform.
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3d monte carlo simulation of Backscattered Electron signal variation across pore solid boundaries in cement based materials
Cement and Concrete Research, 2016Co-Authors: M H N Yio, H S Wong, N R BuenfeldAbstract:Abstract Three-dimensional (3D) Monte Carlo simulation was used to study the variation of Backscattered Electron (BSE) signal across pore-solid boundaries in cement-based materials in order to enhance quantitative analysis of pore structure. The effects of pore size, depth and boundary inclination angle were investigated. It is found that pores down to 1 nm can generate sufficient contrast to be detected. Visibility improves with larger pore size, smaller beam probe size and lower acceleration voltage. However, pixels in shallow pores or near pore boundaries display higher grey values (brightness) than expected due to sampling sub-surface or neighbouring solid material. Thus, cement-based materials may appear less porous or the pores appear smaller than they actually are in BSE images. Simulated BSE images were used to test the accuracy of the Overflow pore segmentation method. Results show the method is generally valid and gives low errors for pores that are 1 μm and greater.
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estimating the original cement content and water cement ratio of portland cement concrete and mortar using Backscattered Electron microscopy
Magazine of Concrete Research, 2013Co-Authors: Hong Seong Wong, Kyle Matter, N R BuenfeldAbstract:In a previous study, a method was proposed to estimate the cement content, water content, free water–cement ratio (w/c) and degree of hydration of hardened Portland cement pastes that have unknown proportions. The method is based on measuring the volumetric fractions of capillary pores, hydration products and unreacted cement using Backscattered Electron microscopy and the volumetric increase of solids during cement hydration. It has the advantage that it is quantitative and does not require comparison with reference samples made with the same materials and cured to the same hydration degree as the unknown sample. However, the method was tested on neat cement pastes only, hence limiting its practical application. In this paper, the extension of the method to Portland cement mortars and concretes is presented, and results are provided, obtained from samples made with three cement types and a range of aggregate content (40–70% vol.), w/c ratio (0·30–0·70) and curing age (3–90 days). The study also involved ...
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estimating transport properties of mortars using image analysis on Backscattered Electron images
Cement and Concrete Research, 2006Co-Authors: H S Wong, N R Buenfeld, M K HeadAbstract:The pore structure of two ordinary Portland cement mortars at water-cement ratio of 0.35 and 0.70 was characterised using quantitative Backscattered Electron imaging. The mortars were cured and conditioned to produce a range of pore structure characteristics. Image analysis was used to characterise the pore structure in terms of simple morphological parameters such as resolvable porosity and the specific surface area. These were found to be correlated to measured transport coefficients (diffusivity, permeability and sorptivity), suggesting the feasibility of image analysis to derive valuable quantitative information describing the pore structure that can be used as input values for a transport prediction model. A simple analytical model incorporating tortuosity and constrictivity was used to predict oxygen diffusivity and a variant of the Kozeny-Carman model was used to predict oxygen permeability. The diffusion model tended to over-predict for the lower w/c ratio mortar, but the general agreement was reasonable, with 90% of the estimated values within a factor of two from the measured values. The modified Kozeny-Carman model, however, over-predicted all permeability values with an error of between half to one order of magnitude.
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Backscattered Electron imaging of the steel concrete interface
Corrosion Science, 2001Co-Authors: G K Glass, R Yang, T Dickhaus, N R BuenfeldAbstract:Abstract Backscattered Electron images were obtained under low vacuum conditions on polished sections of the steel–concrete interface to examine whether the formation of any of the hydration products of cement is favoured at this location. It was observed that the hydration products at the steel are typical of those in the bulk of the cement paste. In particular, there was no general indication of preferential formation of calcium hydroxide at the steel. This provides further support for the suggestion that the early hypothesis concerning the formation of a lime layer at the steel, which inhibits corrosion initiation, should be extended to include the effects of all solids with pH dependent dissolution characteristics. These include both the inhibitive effects of other solid phases that resist a local fall in pH and the aggressive nature of ions like chloride that may be released by a local pH reduction.
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microstructural identification of thaumasite in concrete by Backscattered Electron imaging at low vacuum
Cement and Concrete Research, 2000Co-Authors: R Yang, N R BuenfeldAbstract:A few cases of sulfate attack, involving the formation of thaumasite, have been discovered in site concrete. A technique able to detect small amounts of thaumasite in the presence of ettringite is necessary for developing a detailed understanding of the mechanism of thaumasite sulfate attack and for assessing concrete structures exposed to sulfates. Optical microscopy and X-ray diffraction (XRD) analysis may be used to identify thaumasite in large quantities in a concrete sample. However, the usefulness of optical microscopy is limited by its resolution. When ettringite is abundant, the identification of thaumasite by XRD analysis is very difficult as the d-spacings between thaumasite and ettringite are so similar that the XRD peaks of thaumasite in small quantity may be overwhelmed by the adjacent strong peaks of ettringite. In this study, concrete specimens containing bands of both ettringite and thaumasite were examined by Backscattered Electron imaging, first under low vacuum (9 Pa) and then under high vacuum. Prior to examination, the specimens were dried at 50°C, resin impregnated, then polished. Under high vacuum, thaumasite and ettringite bands appeared heavily cracked and of similar gray scale; they could not be differentiated visually, only by X-ray microanalysis, which is laborious and sometimes imprecise. Under low vacuum, the appearance of ettringite was similar to that in high vacuum, but thaumasite was different, with very few cracks and darker gray scale. This suggests that thaumasite requires a higher vacuum than ettringite to lose its structural water. Thus, low vacuum SEM can be used to identify thaumasite and to differentiate between thaumasite and ettringite.
Peter Fratzl - One of the best experts on this subject based on the ideXlab platform.
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effects of sodium fluoride and alendronate on the bone mineral in minipigs a small angle x ray scattering and Backscattered Electron imaging study
Journal of Bone and Mineral Research, 2009Co-Authors: Peter Fratzl, Peter Roschger, Garry Rodan, Sabine Schreiber, Mariehelene Lafage, Klaus KlaushoferAbstract:Sodium fluoride (NaF), which stimulates bone formation, and bisphosphonates, which reduce bone resorption, are both used in the treatment of osteoporosis, and are binding to bone mineral. In this study, using small-angle X-ray scattering and Backscattered Electron imaging, we analyzed the bone mineral in the vertebrae of minipigs treated with fluoride, with the bisphosphonate alendronate (ALN), or with vehicle. All specimens were investigated blindly. A slight increase in the average thickness of the mineral crystals as well as changes in the structure of the mineral/collagen composite were found in the case of fluoride-treated animals. No differences were found between ALN-treated animals and controls. The changes produced by fluoride are in the same direction as seen in bones from patients treated with NaF, albeit much smaller. They also correlate quantitatively with the reduction in biomechanical properties of bone in fluoride-treated minipigs found in an earlier study with the same animals. These findings suggest that small changes in the structure of the mineral/collagen composite in bone may considerably affect its biomechanical properties. It also emphasizes the delicate balance between the increase of bone mass and deterioration of bone material properties for the effect of fluoride on the biomechanical properties of bone.
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Combination of Nanoindentation and Quantitative Backscattered Electron Imaging Revealed Altered Bone Material Properties Associated with Femoral Neck Fragility
Calcified Tissue International, 2009Co-Authors: N. Fratzl-zelman, Peter Roschger, Klaus Klaushofer, A. Gourrier, M. Weber, B. M. Misof, N. Loveridge, J. Reeve, Peter FratzlAbstract:Osteoporotic fragility fractures were hypothesized to be related to changes in bone material properties and not solely to reduction in bone mass. We studied cortical bone from the superior and inferior sectors of whole femoral neck sections from five female osteoporotic hip fracture cases (74–92 years) and five non fractured controls (75–88 years). The typical calcium content (Ca Peak ) and the mineral particle thickness parameter (T) were mapped in large areas of the superior and inferior regions using quantitative Backscattered Electron imaging (qBEI) and scanning small-angle X-ray scattering, respectively. Additionally, indentation modulus (E) and hardness (H) (determined by nanoindentation) were compared at the local level to the mineral content (Ca Ind) at the indent positions (obtained from qBEI). Ca Peak (-2.2%, P = 0.002), Ca Ind (-1.8%, P = 0.048), E (-5.6%, P = 0.040), and H (-6.0%, P = 0.016)were significantly lower for the superior compared to the inferior region. Interestingly, Ca Peak as well as Ca Ind were also lower (-2.6%, P = 0.006, and –3.7%, P = 0.002, respectively) in fracture cases compared to controls,while E and H did not show any significant reduction. T values were in the normal range, independent of region (P = 0.181) or fracture status(P = 0.551). In conclusion, it appears that the observed femoral neck fragility is associated with a reduced mineral content, which was not accompanied by a reduction in stiffness and hardness of the bone material. This pilot study suggests that a stiffening process in the organic matrix component contributes to bone fragility independently of mineral content.
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance-instrumental stability and interassay variance-reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30-85 years) BMDD measurements were conducted. The patients' medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were <0.3%, <0.4%, <0.9%, and <2.6% of the mean for the intraassay, interassay, intraindividual, and interindividual variations, respectively. In addition, a mean BMDD histogram for transiliac bone specimens was calculated from the 20 aforementioned individuals. The method used allows detection of the degree of mineralization independently from the actual bone volume, a result that seems to be of special interest in the assessment of the effect of treatments for osteoporosis. The power of this technique is demonstrated by using bone from a patient with a metabolic bone disease. In this case of osteomalacia due to celiac disease, the mean calcium concentration in the bone matrix was reduced by 19.3% as compared with normal.
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:Abstract The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance—instrumental stability and interassay variance—reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30–85 years) BMDD measurements were conducted. The patients’ medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were
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Mineralization of cancellous bone after alendronate and sodium fluoride treatment: A quantitative Backscattered Electron imaging study on minipig ribs
Bone, 1997Co-Authors: Peter Roschger, Peter Fratzl, Klaus Klaushofer, Garry RodanAbstract:Fluoride stimulates bone formation, whereas bisphosphonates reduce bone resorption. In clinical trials, both treatments increase bone density, although sodium fluoride (NaF) increases and alendronate (bisphosphonate, ALN) decreases bone turnover. In a comparative study using minipigs an inverse correlation has been reported between bone turnover and elastic modulus. Small-angle X-ray scattering (SAXS) measurements of these bones revealed no structural deterioration of the collagen/mineral composite at the nanometer range for ALN-treated vertebra, whereas a slight increase of the average thickness of the mineral crystals as well as changes of the structure of the collagen/mineral composite were found in the bones of NaF-treated animals. In this study we used quantitative Backscattered Electron imaging (qBSE) to investigate the cancellous bones from ribs of minipigs treated with vehicle, NaF, or ALN. This method provides information on the local mineral concentration in the micrometer range. Mineralization spectra were obtained from each treatment group, and statistically significant differences between ALN and controls were found for the peak position, the peak height, the peak width, and the average calcium (Ca) concentration of the mineral distribution. The results reveal that the cancellous bone matrix was more uniformly mineralized after ALN treatment. The reduced bone turnover induced by ALN, documented histomorphometrically could be at the origin of this phenomenon. No significant differences were detected between NaF and control. Together with the earlier SAXS data these results may explain in part the increase in bone density and the improvement of biomechanical properties observed after ALN treatment in animals acid in osteoporotic patients.
Peter Roschger - One of the best experts on this subject based on the ideXlab platform.
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effects of sodium fluoride and alendronate on the bone mineral in minipigs a small angle x ray scattering and Backscattered Electron imaging study
Journal of Bone and Mineral Research, 2009Co-Authors: Peter Fratzl, Peter Roschger, Garry Rodan, Sabine Schreiber, Mariehelene Lafage, Klaus KlaushoferAbstract:Sodium fluoride (NaF), which stimulates bone formation, and bisphosphonates, which reduce bone resorption, are both used in the treatment of osteoporosis, and are binding to bone mineral. In this study, using small-angle X-ray scattering and Backscattered Electron imaging, we analyzed the bone mineral in the vertebrae of minipigs treated with fluoride, with the bisphosphonate alendronate (ALN), or with vehicle. All specimens were investigated blindly. A slight increase in the average thickness of the mineral crystals as well as changes in the structure of the mineral/collagen composite were found in the case of fluoride-treated animals. No differences were found between ALN-treated animals and controls. The changes produced by fluoride are in the same direction as seen in bones from patients treated with NaF, albeit much smaller. They also correlate quantitatively with the reduction in biomechanical properties of bone in fluoride-treated minipigs found in an earlier study with the same animals. These findings suggest that small changes in the structure of the mineral/collagen composite in bone may considerably affect its biomechanical properties. It also emphasizes the delicate balance between the increase of bone mass and deterioration of bone material properties for the effect of fluoride on the biomechanical properties of bone.
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Combination of Nanoindentation and Quantitative Backscattered Electron Imaging Revealed Altered Bone Material Properties Associated with Femoral Neck Fragility
Calcified Tissue International, 2009Co-Authors: N. Fratzl-zelman, Peter Roschger, Klaus Klaushofer, A. Gourrier, M. Weber, B. M. Misof, N. Loveridge, J. Reeve, Peter FratzlAbstract:Osteoporotic fragility fractures were hypothesized to be related to changes in bone material properties and not solely to reduction in bone mass. We studied cortical bone from the superior and inferior sectors of whole femoral neck sections from five female osteoporotic hip fracture cases (74–92 years) and five non fractured controls (75–88 years). The typical calcium content (Ca Peak ) and the mineral particle thickness parameter (T) were mapped in large areas of the superior and inferior regions using quantitative Backscattered Electron imaging (qBEI) and scanning small-angle X-ray scattering, respectively. Additionally, indentation modulus (E) and hardness (H) (determined by nanoindentation) were compared at the local level to the mineral content (Ca Ind) at the indent positions (obtained from qBEI). Ca Peak (-2.2%, P = 0.002), Ca Ind (-1.8%, P = 0.048), E (-5.6%, P = 0.040), and H (-6.0%, P = 0.016)were significantly lower for the superior compared to the inferior region. Interestingly, Ca Peak as well as Ca Ind were also lower (-2.6%, P = 0.006, and –3.7%, P = 0.002, respectively) in fracture cases compared to controls,while E and H did not show any significant reduction. T values were in the normal range, independent of region (P = 0.181) or fracture status(P = 0.551). In conclusion, it appears that the observed femoral neck fragility is associated with a reduced mineral content, which was not accompanied by a reduction in stiffness and hardness of the bone material. This pilot study suggests that a stiffening process in the organic matrix component contributes to bone fragility independently of mineral content.
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new observations on bone quality in mild primary hyperparathyroidism as determined by quantitative Backscattered Electron imaging
Journal of Bone and Mineral Research, 2007Co-Authors: Peter Roschger, David W Dempster, Hua Zhou, Eleftherios P Paschalis, Shonni J Silverberg, Elisabeth Shane, John P Bilezikian, Klaus KlaushoferAbstract:Bone mineralization density distribution, an important aspect of bone material quality, was determined in mild primary hyperparathyroidism using quantitative Backscattered Electron imaging. A strong correlation between bone turnover status and degree and heterogeneity of mineralization was found. Further studies are needed before we can draw conclusions about fracture risk in this disorder. Introduction: Mild primary hyperparathyroidism (PHPT) is best characterized by asymptomatic hypercalcemia, most commonly in the absence of classical signs and symptoms. Hence, there is need to characterize this disorder with particular attention to the skeleton. Materials and Methods: We analyzed bone mineralization density distribution (BMDD) in iliac crest bone biopsies from patients with PHPT in 51 subjects (16 men, 28–68 years of age; 35 women, 26–74 years of age) by quantitative Backscattered Electron imaging (qBEI). The BMDD variables quantified are as follows: CaMEAN, the weighted mean calcium concentration; CaPEAK, the most frequent Ca concentration; CaWIDTH, the width of the distribution, a measure of the mineralization homogeneity; CaLOW, the percentage of bone area that is mineralized below the fifth percentile in the reference range. The results were compared with a reference range that we have previously established. Results: The greatest differences were found in CaWIDTH (+15.7%, p < 0.0001) and CaLOW (+44.7%, p < 0001), both of which were significantly higher in PHPT than control. CaMEAN was significantly lower (−2.5%, p < 0.0001) in PHPT compared with controls. These differences were reversed in seven patients who underwent parathyroidectomy. CaMEAN and CaPEAK variables were negatively, whereas CaWIDTH and CaLOW were positively, correlated with dynamic variables of bone formation: mineralizing surface and bone formation rate as determined by histomorphometry. (r = ±0.3–0.8; p = 0.05–0.0001). These results, which represent the first BMDD measurements in mild PHPT using qBEI, show a reduction in the average mineralization density and an increase in the heterogeneity of the degree of mineralization. These changes correlate significantly with the bone turnover rate. Conclusions: The results are consistent with our previous observations of increased bone turnover in this disease, and consequently, reduced mean age of bone tissue. Reduced mineralization density in patients with PHPT would be expected to reduce the stiffness of bone tissue. These observations are relevant to considerations of fracture risk in PHPT.
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:Abstract The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance—instrumental stability and interassay variance—reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30–85 years) BMDD measurements were conducted. The patients’ medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were
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validation of quantitative Backscattered Electron imaging for the measurement of mineral density distribution in human bone biopsies
Bone, 1998Co-Authors: Peter Roschger, Peter Fratzl, J Eschberger, Klaus KlaushoferAbstract:The measurement of bone mineral density (BMD) using X-rays is usually employed to monitor the mineral content in a given portion of bone. However, this method cannot differentiate between changes in bone volume or in degree of mineralization of the bone matrix. In contrast to BMD, bone mineral density distribution (BMDD), as measured on bone sections by quantitative Backscattered Electron imaging (qBEI), is able to distinguish differences in the degree of mineralization. For routine clinical research, we have validated the method of calibration and standardization of the Backscattered Electron (BE) signal. Carbon and aluminum were used as reference materials for BE gray levels and osteoid and apatite for calcium concentration. Experiments were performed to get knowledge about precision (intraassay variance-instrumental stability and interassay variance-reproducibility) and accuracy (standardization) of this method as well as the biological variance (intraindividual and interindividual) in human bone. On transiliac biopsies or necropsies from 20 individuals having had accidental death (13 females, 7 males, age 30-85 years) BMDD measurements were conducted. The patients' medical history as well as the histomorphology of these bones showed no evidence of metabolic bone disease. For instance, the standard deviations of the weighted mean calcium concentrations were <0.3%, <0.4%, <0.9%, and <2.6% of the mean for the intraassay, interassay, intraindividual, and interindividual variations, respectively. In addition, a mean BMDD histogram for transiliac bone specimens was calculated from the 20 aforementioned individuals. The method used allows detection of the degree of mineralization independently from the actual bone volume, a result that seems to be of special interest in the assessment of the effect of treatments for osteoporosis. The power of this technique is demonstrated by using bone from a patient with a metabolic bone disease. In this case of osteomalacia due to celiac disease, the mean calcium concentration in the bone matrix was reduced by 19.3% as compared with normal.
A Boyde - One of the best experts on this subject based on the ideXlab platform.
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iodine vapor staining for atomic number contrast in Backscattered Electron and x ray imaging
Microscopy Research and Technique, 2014Co-Authors: A Boyde, Fergus A Mccorkell, Graham K Taylor, Richard J Bomphrey, Michael DoubeAbstract:Iodine imparts strong contrast to objects imaged with Electrons and X-rays due to its high atomic number (53), and is widely used in liquid form as a microscopic stain and clinical contrast agent. We have developed a simple technique which exploits elemental iodine's sublimation-deposition state-change equilibrium to vapor stain specimens with iodine gas. Specimens are enclosed in a gas-tight container along with a small mass of solid I2. The bottle is left at ambient laboratory conditions while staining proceeds until empirically determined completion (typically days to weeks). We demonstrate the utility of iodine vapor staining by applying it to resin-embedded tissue blocks and whole locusts and imaging them with Backscattered Electron scanning Electron microscopy (BSE SEM) or X-ray microtomography (XMT). Contrast is comparable to that achieved with liquid staining but without the consequent tissue shrinkage, stain pooling, or uneven coverage artefacts associated with immersing the specimen in iodine solutions. Unmineralized tissue histology can be read in BSE SEM images with good discrimination between tissue components. Organs within the locust head are readily distinguished in XMT images with particularly useful contrast in the chitin exoskeleton, muscle and nerves. Here, we have used iodine vapor staining for two imaging modalities in frequent use in our laboratories and on the specimen types with which we work. It is likely to be equally convenient for a wide range of specimens, and for other modalities which generate contrast from Electron- and photon-sample interactions, such as transmission Electron microscopy and light microscopy. Microsc. Res. Tech. 77:1044–1051, 2014. © 2014 The Authors. Microscopy Research Technique published by Wiley Periodocals, Inc.
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staining plastic blocks with triiodide to image cells and soft tissues in Backscattered Electron sem of skeletal and dental tissues
European Cells & Materials, 2012Co-Authors: A BoydeAbstract:Backscattered Electron scanning Electron microscopy (BSE SEM) is an invaluable method for studying the histology of the hard, mineralised components of poly-methyl methacrylate (PMMA) or other resin embedded skeletal and dental tissues. Intact tissues are studied in micro-milled or polished block faces with an Electron-optical section thickness of the order of a half to one micron and with the area of the section as big as a whole – large or small – bone organ. However, BSE SEM does not give information concerning the distribution of uncalcified, ‘soft’, cellular and extracellular matrix components. This can be obtained by confocal microscopy of the same block and the two sorts of images merged but the blocks have to be studied in two microscope systems. The present work shows a new, simple and economic approach to visualising both components by using the triiodide ion in Lugol’s iodine solution to stain the block surface prior to the application of any conductive coating – and the latter can be omitted if charging is suppressed by use of poor vacuum conditions in the SEM sample chamber. The method permits the use of archival tissue, and it will be valuable in studies of both normal growth and development and pathological changes in bones and joints, including osteoporosis and osteoarthritis, and tissue adaptation to implants.
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mean atomic number and Backscattered Electron coefficient calculations for some materials with low mean atomic number
Scanning, 2006Co-Authors: P G T Howell, K M W Davy, A BoydeAbstract:In modelling Electron backscattering from solids using Monte Carlo simulations, knowledge of mean atomic number, mean atomic weight, and density of the bulk material are required. We studied four different ways in common useforthe calculation of mean atomic number. An alternative and improved approach is to calculate the mean Backscattered Electron (BSE) coefficient, η, from a knowledge of the elemental composition and values of η for the elements. Again, we studied a number of formulae suggested for this averaging process. As it is not possible to measure η directly for a number of elements, the method used to interpolate between elements with known η was also examined. In addition, we obtained experimental backscattering relationships for topography-free samples of poly (methylmethacrylate) (PMMA), carbon, aluminium, and a series of novel halogenated resins, all solids with relatively low mean atomic numbers, and calcified tissues. None of the methods for determining mean atomic number placed the materials of interest in the correct sequence of their experimentally determined BSE peaks: the data differed widely between the individual methods. The averaged BSE coefficient calculated by the Castaing formula gave the best agreement with the experimentally derived data.
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mineralisation density of human mandibular bone quantitative Backscattered Electron image analysis
Journal of Anatomy, 1998Co-Authors: V J Kingsmill, A BoydeAbstract:This study examined the tissue level mineralisation density distribution in mandibles from 88 adult humans. Mandibles (19-96 y) were sectioned vertically in midline (MID), mental foramen (MF), and third molar (M3) regions. Surgical fragments from M3 were obtained from individuals aged 16-38 y. All specimens were cleaned, embedded in PMMA, micromilled and examined by digital 20 kV Backscattered Electron (BSE) stereology. Quantitation was based on rescaling image histograms to the signal range between a monobrominated (0) and a monoiodinated (255) dimethacrylate resin standard. Mineralisation density increased with age (r=0.70; P < 0.0001): the mean for 39 individuals aged between 16 and 50 y was significantly lower (P < 0.0001) than for 35 individuals over 51 y (mean (+/-S.E.M.): 158.20 (1.63) and 174.71 (1.27) normalised grey level units respectively). There was good correlation in mean mineralisation density between different sites in the same mandible, but MID was significantly less highly mineralised than the other sites: MID 173.90, MF 177.34, M3 177.11 (P < 0.002 and 0.01 for MF and M3 respectively; paired t test), as was the alveolar bone density when compared with the bone of the inferior cortex (e.g. MID: 171.13 (1.53) and 174.46 (1.14) P < 0.0001). No sex difference was found. Partially dentate mandibles generally had regions of higher mineralisation than fully dentate and edentulous mandibles. The lowest density bone occurred at the alveolar crest anteriorly and superolingually at M3, matching sites of net resorption following tooth loss. Highest densities were found inferolingually at MID, inferiorly at MF and buccally at M3, matching the sites thought to experience the highest functional strains. This stresses the importance that local factors may have in the remodelling of the edentulous mandible. Morphology showed that there is a preponderance of highly mineralised cement lines, and of packets containing dead, mineralised, osteocytes.
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a quantitative Backscattered Electron imaging study of hypomineralization and hypoplasia in fluorosed dental enamel of deer
Annals of Anatomy-anatomischer Anzeiger, 1997Co-Authors: H Kierdorf, Uwe Kierdorf, A BoydeAbstract:Mineral content and distribution of fluorosed and unfluorosed (control) dental enamel of roe deer and red deer cheek teeth were analyzed using digital Backscattered Electron (BSE) imaging of PMMA-embedded specimens. Compared to the controls, the fluorosed enamel exhibited various aberrations resulting from a fluoride-induced disturbance of the processes involved in enamel formation. Thus, the presence of surface hypoplasias and an enhancement of the incremental pattern in the fluorosed enamel are evidence of a fluoride impact on the secretory ameloblasts, whereas a (subsurface) hypomineralization of different depth and extent is indicative of a fluoride effect on the maturation stage of amelogenesis. The marked variation in the severity of enamel hypomineralization seen along the coronocervical axis of a specimen pointed to a fluoride impact of varying intensity during this period of tooth development. Our observations further indicated that, in some locations, ameloblasts severely affected by fluoride during enamel matrix formation were able to recover from this insult and to function quite normally during the maturation stage of amelogenesis. A major advantage of the BSE imaging technique used in the present study over other methods is that it allows for a combination of micromorphological information with quantitative data on the mineralization of the analyzed tissue, which proved to be very useful for the characterization of fluoride-induced changes in dental enamel.
