RESUMEN
Tick-borne pathogens in the genus Ehrlichia cause emerging zoonoses. Although laboratory mice are susceptible to Ehrlichia infections, many isolates do not cause clinical illness. In contrast, the Ixodes ovatus Ehrlichia-like agent (IOE) causes disease and immune responses in mice comparable to the human illness caused by Ehrlichia chaffeensis. No culture system had been developed for IOE, however, which limited studies of this pathogen. We reasoned that endothelial and tick cell lines could potentially serve as host cells, since the IOE is found in ticks and in endothelial cells in mice. Infected spleen cells from RAG-deficient mice were overlaid onto ISE6 and RF/6A cultures, and colonies typical of Ehrlichia were noted in RF/6A cells within 2 weeks. Infection of ISE6 cells was established after transfer of IOE from RF/6A cells. Electron microscopy revealed densely packed inclusions in infected RF/6A and ISE6 cells; these inclusions contained copious amounts of filamentous structures, apparently originating from Ehrlichial cells. In particular, within RF/6A cells the structures assumed an ordered morphology of finely combed hair. IOE from RF/6A cells, when inoculated into C57BL/6 and RAG-deficient mice, induced fatal disease. These data reveal unique structural features of IOE that may contribute to the pathogen's high virulence.
Asunto(s)
Ehrlichia/ultraestructura , Células Endoteliales , Ixodes/microbiología , Garrapatas , Animales , Línea Celular , Ehrlichia/patogenicidad , Ehrlichiosis/microbiología , Células Endoteliales/microbiología , Células Endoteliales/ultraestructura , Genes RAG-1 , Humanos , Macaca mulatta , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Enfermedades de los Roedores/microbiología , Garrapatas/citología , Garrapatas/microbiologíaRESUMEN
Recent studies suggest that trace metals emitted by internal combustion engines are derived mainly from combustion of lubrication oil. This hypothesis was examined by investigation of the formation of particulate matter emitted from an internal combustion engine in the absence of fuel-derived soot. Emissions from a modified CAT 3304 diesel engine fueled with hydrogen gas were characterized. The role of organic carbon and metals from lubrication oil on particle formation was investigated under selected engine conditions. The engine produced exhaust aerosol with log normal-size distributions and particle concentrations between 10(5) and 10(7) cm(-3) with geometric mean diameters from 18 to 31 nm. The particles contained organic carbon, little or no elemental carbon, and a much larger percentage of metals than particles from diesel engines. The maximum total carbon emission rate was estimated at 1.08 g h(-1), which is much lower than the emission rate of the original diesel engine. There was also evidence that less volatile elements, such as iron, self-nucleated to form nanoparticles, some of which survive the coagulation process.
Asunto(s)
Contaminantes Atmosféricos/análisis , Hidrógeno , Aceites Industriales , Material Particulado/análisis , Emisiones de Vehículos/análisis , Carbono/análisis , Lubrificación , Metales/análisis , Tamaño de la PartículaRESUMEN
A woman and her son were referred because of prolonged thrombocytopenia. Ultrastructural studies revealed the presence of giant organelles in their cells never observed previously in human platelets. Our initial reports described the evolution of two types of giant organelles in patient megakaryocytes and platelets. The last report also demonstrated that the large organelles in platelet whole mount preparations were inherently electron opaque like serotonin-rich dense bodies in normal and patient platelets. In the present study analytical electron microscopy of whole mount preparations from the patients and controls revealed that the inherently electron opaque dense and hexagonal precursor fragments, chains, clusters and giant organelles contained high concentrations of calcium and phosphorous, the major elements in normal dense bodies. The ratio of calcium to phosphorous in patient giant organelles was nearly the same as in normal platelet dense bodies. However, as shown in the previous study, levels of serotonin and adenine nucleotides were normal in patient platelets, and giant organelles and their contents were not secreted following activation of platelets with thrombin. Thus, despite the similarity in mineral content responsible for electron density, the giant organelles in patient platelets do no appear to be aberrant serotonin storage organelles.
Asunto(s)
Plaquetas/ultraestructura , Gránulos Citoplasmáticos/química , Gránulos Citoplasmáticos/patología , Megacariocitos/ultraestructura , Trombocitopenia/patología , Nucleótidos de Adenina/análisis , Adulto , Plaquetas/patología , Estudios de Casos y Controles , Salud de la Familia , Femenino , Humanos , Recién Nacido , Masculino , Megacariocitos/patología , Microscopía Electrónica , Activación Plaquetaria , Serotonina/análisis , Análisis Espectral , Trombocitopenia/genética , Rayos XRESUMEN
Platelets from a mother and son with prolonged thrombocytopenia were shown in previous studies to contain giant organelles that developed in megakaryocytes and continued to evolve in circulating cells. Whole mount platelet preparations revealed that the large organelles were electron opaque like the serotonin-rich dense bodies in normal and patient platelets, and analytical electron microscopy revealed they contained large amounts of calcium and phosphorous in a ratio close to that found in normal platelet dense bodies. However, differences in physiology, biochemistry and morphology indicated the large opaque bodies and target-organelles in patient platelets were not aberrant dense bodies. The present study has shown that the giant organelles contain peroxidase activity like primary lysosomes in polymorphonuclear (PMN) leukocytes. Further, the giant organelles in patient platelets contain acid phosphatase activity. Analytical electron microscopy demonstrated that cerium, the capture ion for the acid phosphatase reaction product, was present in the opaque organelles with calcium and phosphorous, but not present in their normal dense bodies. Since normal sized lysosomes appeared to be reduced in patient platelets, it was concluded that the large structures were abnormal lysosomes, or fused with normal platelet lysosomes during their development. Similar giant lysosomes were not present in other patient blood cells. As a result the disorder can be considered a unique lysosomal disease of platelets.