RESUMEN
The present paper covers the results of different transmission electron microscopy studies on silver halide microcrystals. Pure AgBr as well as core-shell AgBr-AgBrI crystals are investigated. In the former parallel and non-parallel twinning modes yielding tabular and needle- or tetrahedral-shaped microcrystals, respectively, are discussed. Also the short-range-order of Ag+ interstitials around the twin planes as determined from diffuse intensity in reciprocal space is described. The latter yields a technique to determine the variant in which dislocations are located in certain core-shell microcrystals. The introduction of iodine also results in the presence of inclined stacking faults in the shell and of long-range iodine ordering on the crystal surface.
Asunto(s)
Microscopía Electrónica/métodos , Compuestos de Plata/química , Bromuros/química , Cristalografía/métodos , Aumento de la Imagen/métodos , Yoduros/química , FotograbarRESUMEN
The few studies concerning HCV genotypes in hemodialyzed patients concerned small groups of patients, issued from single units. Using the RFLP typing method in the 5' non-coding region (5' NCR), we performed the genotyping of HCV strains of 80 patients issued from 14 Belgian dialysis units. Forty-seven of the 80 patients were also tested by Inno-Lipa II (Innogenetics, Gent, Belgium). Sixty-four of 80 patients (80%) were infected with subtype 1b, 2 (2.5%) with subtype 1a, 6 (7.5%) with subtype 2a and 1 (1%) with subtype 2b; 6 patients (7.5%) showed a type 4 and 2 patients (2.5%) a type 5 infection, respectively. Only 1 patient (1%) showed a mixed infection (1a and 1b). In the 47 patients tested by both methods, we observed a very good agreement (98%) between RFLP and Inno-Lipa II's results. Our multicentric study detected HCV genotypes 4 or 5 in 8/80 (10%) of hemodialyzed patients in Belgium. The substantial prevalence of these genotypes could not be fully explained by a nosocomial spread of HCV infection: indeed, four patients belonged to dialysis units located in different cities, and two appeared infected with distinct subtypes in a same unit. Thus, the discovery of a "rare" HCV genotype in several hemodialyzed patients does not always point to nosocomial HCV transmission.