RESUMEN
Se determinó el porcentaje de retención de tres fracciones de materia orgánica particulada gruesa (MOPG) y el efecto de la magnitud del caudal sobre la retención de la materia orgánica particulada (MOP), durante un período de cinco meses en tres sectores de una quebrada tropical de montaña ubicada en los Cerros Orientales de Bogotá Colombia. La condición tropical del sistema, mostró un patrón de caudal constante aunque pudo diferenciarse un período de alta y baja descarga. Los resultados mostraron que el valor promedio del porcentaje de retención fue relativamente alto, presentándose una asociación negativa entre la magnitud del caudal y el porcentaje de retención de las fracciones MOPG, siendo más evidente en partículas pequeñas (rs=0,74; p.
Retention percentage of three fractions of coarse particulate organic matter (MOPG) and discharge effect over retention of particulate organic matter (MOP) were studied during five months in three sectors of a tropical mountain stream, at Eastern hills of Bogotá Colombia. The tropical condition of the system, showed a pattern of constant discharge although could be a different period from low and high discharge. Results showed as average value of retention percentage was high, with a negative association between flow magnitude and percentage of retention for each MOPG fraction, being more evident in small particles (rs=0.74, p.
RESUMEN
Osteoblast or bone marrow stromal cell-derived RANKL is the major effector molecule essential for osteoclastogenesis. Previous studies have shown that tetracyclines have beneficial therapeutic effects in the prevention and treatment of inflammatory bone disease including periodontal disease. Periodontal ligament cells are thought not only to play an important role in the progression of periodontal disease, but to play an important role in alveolar bone remodeling. Previous studies indicated that receptor activation of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) are expressed in periodontal ligament cells by pro-inflammatory cytokine, such as IL-1beta and TNF-alpha . This study was designed to investigate the inhibitory effect of doxycycline on RANKL and OPG mRNA in rat periodontal ligament cells induced by IL-1beta(1 ng/ml). The results are as follows; 1. MTT assay showed that doxycycline at the concentration of 1-50 microgram/ml didn't result in statistically significant cell death at day 1 and 3 . 2. RANKL mRNA expression was increased to 2.6 folds by IL-1beta. When cells were treated with doxycycline (50 microgram/ml), IL-1beta-induced mRANKL expression was reduced by 33%. In contrast to RANKL, OPG mRNA expression was not inhibited by pre-treatment with doxycycline. These results suggest that doxycycline decrease the expression of mRANKL resulting in regulation of osteoclastogenesis in rat periodontal ligament cells.