RESUMO
A novel secreted glycoprotein that regulates bone resorption has been identified. The protein, termed Osteoprotegerin (OPG), is a novel member of the TNF receptor superfamily. In vivo, hepatic expression of OPG in transgenic mice results in a profound yet nonlethal osteopetrosis, coincident with a decrease in later stages of osteoclast differentiation. These same effects are observed upon administration of recombinant OPG into normal mice. In vitro, osteoclast differentiation from precursor cells is blocked in a dose-dependent manner by recombinant OPG. Furthermore, OPG blocks ovariectomy-associated bone loss in rats. These data show that OPG can act as a soluble factor in the regulation of bone mass and imply a utility for OPG in the treatment of osteoporosis associated with increased osteoclast activity.
Assuntos
Densidade Óssea/fisiologia , Glicoproteínas/fisiologia , Osteoclastos/efeitos dos fármacos , Osteopetrose/genética , Receptores Citoplasmáticos e Nucleares , Sequência de Aminoácidos , Animais , Reabsorção Óssea , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Cricetinae , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Glicoproteínas/genética , Glicoproteínas/metabolismo , Glicoproteínas/farmacologia , Humanos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Especificidade de Órgãos , Osteoclastos/citologia , Osteopetrose/metabolismo , Osteoprotegerina , Ovariectomia , RNA Mensageiro/análise , Ratos , Ratos Endogâmicos F344 , Receptores do Fator de Necrose Tumoral , Proteínas Recombinantes de Fusão , Homologia de Sequência de AminoácidosRESUMO
Two cases of air embolism in patients anaesthetized in the sitting position are described. The emboli, though producing no signs and therefore probably small, were readily detected by the fall in the end tidal CO2 fraction. Techniques for the detection of air emboli are briefly reviewed.
