RESUMEN
Bone tissue samples of thoracic vertebrae taken from 32 cadavers of males and females who had suddenly died at ages were examined ranging from 20 to 45 and from 70 to 89 years. The samples were studied by means of quantitative phase X-ray analysis which showed the mineral component of the crystalline phase to be 55.8 +/- 2.1 and 56.6 +/- 2.2 per cent in the young men and women, and that of the older-age group to be 63.9 +/- 1.9 and 66.1 +/- 2.6 per cent, respectively. The hydroxyapatite crystals had the shape of a hexagonal prism with 23.8-27.3 nm allongated along the C axis. The crystal dimensions along the a axis in the young males were 7.0 +/- 0.15 nm, that of females were 6.8 +/- 0.2 nm; in the old-age group, the dimensions were 7.7 +/- 0.2 and 7.4 +/- 0.14 nm, respectively. The volume of the crystallized particles in the young was 1387 +/- 66 nm3 and increased with age to 1748 +/- 117 nm3. The findings on the ultrastructure of the mineral component and its age-related changes may be used to study the physicochemical properties of the bone and to reveal the essence of aging of the locomotor apparatus and of the organism as a whole.
Asunto(s)
Hidroxiapatitas/análisis , Vértebras Torácicas/análisis , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Cristalización , Microanálisis por Sonda Electrónica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Modelos Biológicos , Factores SexualesRESUMEN
We tried to determine whether mineral-equivalent measurements that were obtained using computed tomography could be used to predict the mechanical properties of vertebral trabecular bone. Vertebral bodies that had been obtained during routine autopsy were evaluated by computed tomography. The mechanical properties of the vertebral trabecular bone were determined by subjecting cylindrical specimens to simple compression until failure occurred. The ultimate strength and elastic modulus were determined from load time curves, using constant displacement rate loading. Atomic absorption spectrophotometry was used to determine the weight per cent calcium of each specimen, and quantitative light microscopy was used to determine area fraction bone. Significant positive correlations were found between the observed mechanical properties of the trabecular bone and the equivalent mineral density as measured by computed tomography. Compressive strength (r = 0.720), elastic modulus (r = 0.574), trabecular calcium density (r = 0.780), and area fraction bone (r = 0.579) were all correlated with the equivalent mineral density.
Asunto(s)
Vértebras Lumbares/análisis , Vértebras Torácicas/análisis , Tomografía Computarizada por Rayos X , Anciano , Fenómenos Biomecánicos , Calcio/análisis , Densitometría , Humanos , Vértebras Lumbares/diagnóstico por imagen , Persona de Mediana Edad , Preservación Biológica , Espectrofotometría Atómica , Resistencia a la Tracción , Vértebras Torácicas/diagnóstico por imagenRESUMEN
The measurement of the mineral content of bone by localised neutron activation was performed in the hand in 58 women aged between 23 and 87 years and simultaneously in the hand and the thoracic spine (from the 5th to the 9th thoracic vertebra) in 46 women aged between 50 and 80 years, all free of any bone disease. The neutron flow was emitted by Californium 252. The bone calcium mass was calculated from the peak of radioactivity emitted by Ca 49 with an energy of 3.10 MeV, measured by means of a sodium iodide scintillation detector. The bone volumes were estimated indirectly by planimetry. The results were expressed as the volumic concentration of calcium in the bones of the hand and the vertebrae. The calcium concentration of the bones of the hand decreases with age, especially between 50 and 60 years. The calcium concentration of the vertebrae decreases more markedly with a significant negative correlation (r = - 0.550; p less than 0.05). The correlation is particularly significant (r = - 0.878) in the 16 women aged between 50 and 65 years with a calcium concentration in the bones of the hand within the normal range. The correlation between the calcium concentration in the vertebrae and age was no longer significant after the age of 65 years, whatever the value of the calcium concentration of the bones of the hand. A significant correlation (r = 0.660; p less than 0.05) was observed between the vertebral calcium and the calcium in the bones of the hands in women aged between 50 and 65 years, which disappeared after this age.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Huesos/análisis , Calcio/análisis , Adulto , Anciano , Envejecimiento , Huesos del Carpo/análisis , Densitometría , Femenino , Humanos , Menopausia , Persona de Mediana Edad , Análisis de Activación de Neutrones , Vértebras Torácicas/análisisRESUMEN
The interrelationship between the bone-mineral content of sites on the radius or ulna and that of the femoral neck and lower thoracic vertebrae of twenty-four human skeletons was determined. The average correlation coefficients, -/r, were 0.82 and 0.57. Regression analysis showed that the bone-mineral content of the radius provides a good estimate of the bone-mineral content of the femoral neck (standard error of estimate approximately 16 per cent). Multiple regression analysis using the age of the subject and the bone-mineral content of the radius provides an equation with a similar standard error of estimate for the vertebrae.