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Factors Associated with Cortical and Trabecular Bone Loss as Quantified by Peripheral Computed Tomography (pQCT) at the Ultradistal Radius in Aging Women (1997)

Boonen, S. ; Cheng, X. G. ; Nijs, J. ; [et al.]

Springer

Calcified tissue international 60 (1997), S. 164 -170

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ISSN: 1432-0827

Keywords: Key words: Peripheral quantitative computed tomography (pQCT) — Age-related bone loss — Growth hormone — IGF-I.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Abstract. Peripheral quantitative computed tomography (pQCT) allows the separate determination of cortical and trabecular bone mineral density in the peripheral skeleton. This cross-sectional study was designed to examine the effects of healthy aging on pQCT measurements at the ultradistal radius. In a well-defined sample of 129 community-based women, aged 70–87 years, the differences in cortical and trabecular density over the age range were equivalent to losses of −0.41% and −0.65% per year, respectively. To investigate the mechanism of this age-related decline, we assessed relationships between both parameters and height, weight, body mass index, dietary calcium intake, grip strength, and serum concentrations of insulin-like growth factor-I (IGF-I), calcidiol (25(OH)D3), calcitriol (1,25(OH)2D3), parathyroid hormone (PTH), and sex hormone binding globulin (SHBG). Multiple regression was used to adjust for potential confounders. Age was not significant after controlling for other covariables. Body mass index, grip strength, serum IGF-I, 25(OH)D3, and PTH (1–84) were found to be independent predictors of total bone density. Including (total or free) 1,25(OH)2D3 did not improve the model precision. These findings provide evidence that, among other factors, the activity of the growth hormone-IGF-I-axis is of importance for skeletal integrity. Grip strength, serum IGF-I, and PTH (1–84) were discovered to be significantly related to cortical but not to trabecular density, suggesting that different mechanisms may be involved in compact and cancellous bone loss.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002239900208

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Prevalence of Trabecular Microcallus Formation in the Vertebral Body and the Femoral Neck (1997)

Cheng, X. G. ; Nicholson, P. H. F. ; Lowet, G. ; [et al.]

Springer

Calcified tissue international 60 (1997), S. 479 -484

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ISSN: 1432-0827

Keywords: Key words: Trabecular microcallus formation — Vertebra — Femur — Histomorphometry — Bone density — Osteoporosis.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Abstract. Trabecular microcallus formation (TMF) has been described previously in the human vertebra and femur, but the difference in TMF prevalence at these two sites has not been studied and the role of TMF remains controversial. In this study, the 4th lumbar vertebra (L4) and right proximal femur were removed from 27 male and 23 female cadavers. A 2 cm cube cut from the center of L4 and a 1 cm-thick slice cut from the femoral neck were cleaned, defatted, and dried. The apparent density of the L4 cubes was determined as dry weight/bulk bone volume. Using a dissecting microscope at low magnification (4–60×), TMF were identified and counted in both the vertebral and femoral samples. A 8 mm diameter core was then cut from the center of the L4 cubes in the vertical direction, and selected histomorphometric parameters of the core were evaluated with an X-ray microcomputed tomography system (μ-CT). There was a significantly greater prevalence of TMF in vertebral cubes (82%) than in the femoral slices (11%) (P 〈 0.001). TMF prevalence did not differ significantly between males and females, but the mean number of TMF in the vertebra was significantly (P 〈 0.05) greater in females (15.0/vertebra) than in males (7.7/vertebra). In the vertebra, the majority of the observed TMF were in vertical trabeculae. Subjects over 60 years old had a higher TMF prevalence than those under 60 years old (P 〈 0.01). TMF numbers increased with decreasing apparent density (P 〈 0.05), whereas no significant correlations were found between TMF and bone volume (BV/TV), trabecular number (Tb.N), or trabecular thickness (Tb.Th) as assessed by μ-CT. In two fractured vertebra, very few TMFs (2 and 4, respectively) were observed. These results demonstrated that the occurrence of TMF is strongly related to the anatomical site, probably due to differences in the applied loads and the trabecular structure between sites. The results were consistent with the hypothesis that TMF is a mechanism acting to maintain bone strength, but further studies are needed to clarify this important issue.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002239900266

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Age-Associated Decline in Human Femoral Neck Cortical and Trabecular Content of Insulin-Like Growth Factor I: Potential Implications for Age-Related (Type II) Osteoporotic Fracture Occurrence (1997)

Boonen, S. ; Aerssens, J. ; Dequeker, J. ; [et al.]

Springer

Calcified tissue international 61 (1997), S. 173 -178

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ISSN: 1432-0827

Keywords: Key words: IGF-I — Bone loss — Femoral neck — Cortical — Trabecular — Osteocalcin.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Abstract. Recent evidence suggests that regulatory peptides such as insulin-like growth factor-I (IGF-I) are released locally from bone during resorption, and may then act in a sequential manner to regulate the cellular events required for the coupling of bone formation to resorption. Among other factors, a decrease in bone-associated IGF-I levels could therefore result in remodeling imbalance and contribute to the gradual loss of bone that occurs with age. As the femoral neck region is of primary concern for the clinical manifestations of osteoporosis, the current study was intended to assess the IGF-I contents in femoral neck cortical and trabecular bone from aging individuals. Bone samples from the neck region were obtained at postmortem from 39 females and 35 males, aged 23–92 years. Concentrations of IGF-I and osteocalcin were measured by radioimmunoassay in the supernatants obtained after EDTA and guanidine hydrochloride extraction. The total amount of protein present in the extracts was determined by spectrophotometry. IGF-I levels were significantly lower in trabecular compared with cortical bone. Though femoral neck total protein did not vary with donor age, both IGF-I and osteocalcin were found to decline markedly. Between the ages of 23 and 92 years, average yearly rates of loss of 0.30 and 0.21 ng IGF-I/mg protein were observed in cortical and trabecular bone, respectively, corresponding with net losses of nearly 35% of the cortical skeletal content of IGF-I and 41% of the trabecular skeletal content of IGF-I. These changes in bone-associated IGF-I paralleled those of osteocalcin, consistent with an overall decrease in osteoblast function with aging. In women, the rate of decline was significantly faster for trabecular than for cortical IGF-I, however in men, age-dependent changes in cortical and trabecular IGF-I were similar. These findings support the hypothesis that changes in the local IGF regulatory system over time could be a pathophysiologic component of the age-related (type II) femoral neck osteoporotic syndrome.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002239900318

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Structural and magnetic properties of the layered manganese oxychalcogenides (LaO)_{2}Mn_{2}Se_{2}O and (BaF)_{2}Mn_{2}Se_{2}O (2011)

R. H. Liu, J. S. Zhang, P. Cheng, X. G. Luo, J. J. Ying, Y. J. Yan, M. Zhang, A. F. Wang, Z. J. Xiang, G. J. Ye, and X. H. Chen

American Physical Society (APS)

In: Physical Review B

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Publication Date: 2011-06-01

Description: Author(s): R. H. Liu, J. S. Zhang, P. Cheng, X. G. Luo, J. J. Ying, Y. J. Yan, M. Zhang, A. F. Wang, Z. J. Xiang, G. J. Ye, and X. H. Chen The new layered manganese oxychalcogenides (LaO) 2 Mn 2 Se 2 O and (BaF) 2 Mn 2 Se 2 O, isostructural to (LaO) 2 Fe 2 Se 2 O, were synthesized by solid state reaction method. The single crystals of the former compound were also successfully grown using fusion method. The polycrystalline samples show the semiconductin... [Phys. Rev. B 83, 174450] Published Tue May 31, 2011

Keywords: Magnetism

Print ISSN: 1098-0121

Electronic ISSN: 1095-3795

Topics: Physics

Published by American Physical Society (APS)

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Phase diagram as a function of doping level and pressure in the Eu_{1−x}La_{x}Fe_{2}As_{2} system (2012)

M. Zhang, J. J. Ying, Y. J. Yan, A. F. Wang, X. F. Wang, Z. J. Xiang, G. J. Ye, P. Cheng, X. G. Luo, Jiangping Hu, and X. H. Chen

American Physical Society (APS)

In: Physical Review B

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Publication Date: 2012-03-15

Description: Author(s): M. Zhang, J. J. Ying, Y. J. Yan, A. F. Wang, X. F. Wang, Z. J. Xiang, G. J. Ye, P. Cheng, X. G. Luo, Jiangping Hu, and X. H. Chen We establish the phase diagram of the Eu 1− x La x Fe 2 As 2 system as a function of doping level x and pressure by measuring the resistivity and magnetic susceptibility. Increased pressure can suppress the spin-density-wave (SDW) and structural transitions very efficiently, while enhancing the antiferromag... [Phys. Rev. B 85, 092503] Published Wed Mar 14, 2012

Keywords: Superfluidity and superconductivity

Print ISSN: 1098-0121

Electronic ISSN: 1095-3795

Topics: Physics