RESUMO
Protein-tyrosine kinases (PTKs) are of vital importance in a variety of cell functions. Recent studies have provided considerable insight into the binding of growth factors to tyrosine kinase receptors and the consequent induction of signal pathways that lead to a biologic response. Future studies will further delineate the signals that result in a proliferative response and those that induce a differentiation response. Current studies, reviewed here, indicate an important biologic role for PTKs in the regulation of megakaryocyte development and maturation. Whether PTKs function in megakaryocytes in signaling pathways that are similar to pathways in other cells will need to be examined in future studies.
Assuntos
Hematopoese/fisiologia , Megacariócitos/enzimologia , Proteínas Tirosina Quinases/metabolismo , Animais , Diferenciação Celular , Divisão Celular , Citocinas/genética , Citoplasma/enzimologia , Regulação da Expressão Gênica , Humanos , Megacariócitos/citologia , Proteínas Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de SinaisRESUMO
Liquid hazardous waste disposal in landfills is usually allowed only after solidification/stabilization. Although various procedures are commonly practiced, little is known about the mechanism(s) of the processes. A particular problem is the interference of organics. Small amounts of organics can interfere with the reaction between inorganic sludges and cementitous matrices. The present communication reports studies of the interaction between selected organic hazardous wastes and Type I Portland cement. Microscopic studies of the structural differences between cements set with water and those set with water plus organic liquids are discussed. In these studies the scanning electron microscope is used to observe samples fractured at 78K. The results provide technical background data on the ultimate stability of critical waste constituents solidified by various binding agents.
