RESUMO
There are disparate observations on central and peripheral effects of leptin, but several studies consistently support its role as a link between fat and bone. Bone marrow stroma contains mesenchymal stem cells (MSCs), which differentiate into osteoblasts and adipocytes, among others. In this study we assessed the expression of leptin receptors protein in MSCs from control and osteoporotic postmenopausal donors and their change during osteogenic and adipogenic differentiation. Also, we assessed the effects of leptin on osteogenic and adipogenic differentiation of these cells. We demonstrated high affinity leptin binding (KD = 0.36 +/- 0.02 nM) in both types of cells. Binding was very low under basal, but increased significantly (2-3 times) through osteogenic and adipogenic differentiation. Osteoporotic MSCs showed lower leptin binding capacity than control cells at an early osteogenic and adipogenic differentiation time, which could restrict cell sensitivity to the protective action of leptin. In this regard, we observed that leptin significantly inhibited adipocyte differentiation in control but not in osteoporotic MSCs, while it exerted a low stimulatory effect on calcium deposition (10%-20%) in both types of MSCs cells. In summary, we report the presence of high affinity leptin receptors on control and osteoporotic MSCs, which were modified distinctly by osteogenic and adipogenic stimulation and a direct and distinct effect of leptin on both type of cells.
Assuntos
Mesoderma/metabolismo , Osteoporose/metabolismo , Receptores de Superfície Celular/metabolismo , Células-Tronco/metabolismo , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Diferenciação Celular , Feminino , Humanos , Mesoderma/citologia , Osteoporose/patologia , Receptores para LeptinaRESUMO
"Señuelos extraviados" de un DIU no significan necesariamente perforación uterina. Este artículo decribe un caso de un anillo de Zipper incrustado en un mioma. El diagnóstico fue hecho después de una histeroscopía complicada. Es razonable tener presente esta posibilidad cuando se investiga un caso de "señuelos extraviados". Tal como ha sido publicado, es muy difícil asegurar si el mioma creció alrededor del DIU o el mioma fue perforado al momento de la inserción. Las evidencias histológicas conducen hacia la primera opción