Análisis geométrico de la arquitectura trabecular de un hueso de bovino durante el proceso inducido de desmineralización / Geometric analysis of the trabecular architecture in a bovine bone during the process of induced demineralization

La masificación de la radiología digital ha hecho posible el estudio de diferentes patologías mediante imágenes de alta calidad diagnóstica. Existen diferentes patologías que afectan al tejido óseo, y que producen pérdida del mineral(1). Aquellas patologías se caracterizan por la pérdida de la arquitectura trabecular y un adelgazamiento de la cortical(7), visibles en la radiología. Aquellos cambios llevan al paciente a caer en el riesgo de sufrir futuras fracturas(8), por lo que se considera importante realizar un análisis de la geometría de las trabéculas ante este tipo de patología, con el fin de prever riesgos de fractura. Material y Métodos. Para realizar este estudio, se escogió un fémur de bovino(19). Este fue sumergido en ácido acético al 4 por ciento, con el fin de producir su desmineralización. Se le realizó una medición cada 24 horas mediante la adquisición de imágenes radiológicas, que fueron obtenidas con un equipo digital directo hasta observar cambios radiológicos evidentes en la población trabecular. Las imágenes fueron evaluadas mediante un software de libre acceso llamado ImageJ®(23), realizando mediciones trabeculares mediante la herramienta ROI, y se adquirieron los valores de área, perímetro y circularidad. Resultados. En las 10 trabéculas estudiadas se observaron y cuantificaron cambios en la arquitectura trabecular, aumentando el área en un 124 por ciento, el perímetro en un 53 por ciento y la circularidad se mantuvo en promedio constante. Conclusiones: Mediante la radiología digital, es posible evaluar la arquitectura trabecular mediante parámetros geométricos, los cuales nos indican que existen cambios muy pequeños a lo largo del tiempo. Se observó un aumento de tamaño en las trabéculas, pero sin pérdida de su forma.

Introduction. The mass use of digital radiology has made possible the study of different pathologies through high quality diagnostic images. There are different diseases that affect bone tissue and which produce mineral loss (1). Those diseases are characterized by loss of trabecular architecture and cortical thinning (7), visible in radiology. Those changes lead the patient to suffer the risk of future fractures (8), therefore it is considered important to analyze the geometry of the trabeculae in this kind of pathology in order to anticipate fracture risk. Material and Methods. For this study, a bovine's femur was chosen(19). This was immersed in 4 percent acetic acid to produce demineralization. Measurement was performed (in Clinica Alemana Santiago) every 24 hours by radiological imagings, which were obtained with digital radiology (DR) to observe obvious radiological changes in trabecular population. The images were evaluated by a freely available software called ImageJ® (23), by performing Trabecular measurements using the ROI tool, acquiring the values of area, perimeter and circularity. Results. In the 10 trabeculae studied, we observed and quantified changes in trabecular architecture, increasing the value of average area in 124 percent, perimeter in 53 percent and no change in circularity during the demineralization process. Conclusions. With digital radiography, it is possible to evaluate the trabecular architecture using geometric parameters, which indicate that there are very small changes over time. An increase in size of the trabeculae was observed, trabeculae was observed, but without loss of shape.

Bone mineral density in children with steroid-sensitive nephrotic syndrome.

Objective. To observe the influence of prednisolone treatment on bone mineral density (BMD) in children with idiopathic nephrotic syndrome. Methods. Duel-energy X-ray absorptiometry of lumbar spine (L1-L4) was performed on 40 patients (18 first episode and 22 relapsers) of steroid sensitive idiopathic nephrotic syndrome. Results. Patients of first episode and relapsers had comparable values of mean age, weight, height, body mass index, serum calcium, phosphate, spine area, bone mineral content (BMC) and BMD. Relapsing nephrotic syndrome patients received significantly higher mean total cumulative dose of prednisolone in comparison to first episode (p<0.001). The BMD Z-scores were normal in 39 of 40 (97.5%) patients. On regression analysis, it was found that both BMC and BMD did not correlate with cumulative dose of prednisolone, when other co-variants such as age, weight, height and spine area were adjusted. Conclusion. Bone mineral density in steroid sensitive nephrotic syndrome is unaffected by cumulative dose of prednisolone therapy both in first episode as well as relapser group of patients.

Avaliação das metaloproteinases de matriz -2 e -9 em gatos com desmineralização óssea secundária à tirotoxicose induzida / Evaluation of matrix metalloproteinases -2 and -9 in cats under bone demineralization secondary to induced thyrotoxicosis

Observou-se significativo aumento de atividade das formas ativas das metaloproteinases -2 e -9 em gatos com tirotoxicose induzida e desmineralização óssea. As formas pró e intermediária da metaloproteinase -2 elevaram-se com 14 dias de administração hormonal, porém, posteriormente, houve uma tendência de queda. Observou-se correlação negativa entre a forma ativa das metaloproteinases de matriz -2 e -9 e a densidade mineral óssea da extremidade distal do rádio. Os resultados sugerem aumento da degradação da matriz colágena secundária com a elevação dos hormônios tiroidianos.

Significant increase of activity of active forms of matrix metalloproteinases -2 and -9 in cats under induced thyrotoxicosis and bone demineralization was observed. Pro and intermediated forms of matrix metalloproteinases -2 and -9 increased at 14 days of hormonal treatment, followed by decrease tendency. A negative correlation between active forms of matrix metalloproteinases -2 and -9 and bone mineral density of radius distal extremity was also observed. The results suggest an increase of collagen matrix degradation secondary to high levels of thyroid hormones.