Abstract: An environmental scanning electron microscope is provided which is capable of only detecting backscattered electron signals emanating from the specimen with the detector assembly be positioned within the gaseous environment of the ESEM specimen chamber. This detector assembly includes a biased converter plate and a collection grid/collection plate/collector ring arrangement. The primary beam passes through the final pressure limiting aperture formed in the converter plate and then through a central aperture of the collection grid/plate/ring before striking the sample. The collection grid is held at ground potential and therefore does not collect secondary electron signals generated at the sample. The backscattered electrons are not collected by the collector grid/plate/ring and strike the converter plate creating converted backscattered electrons. The converted backscattered electrons are amplified in the gas by the electric field created between the converter plate and the collection grid.

Abstract: Attenuated vaccinia or canarypox recombinant viruses containing DNA coding for a cytokine and/or a tumor associated antigen, as well as methods and compositions employing the viruses, are disclosed and claimed. The recombinant viruses can be NYVAC or ALVAC recombinant viruses. The DNA can code for at least one of: human tumor necrosis factor; nuclear phosphoprotein p53, wildtype or mutant; human melanoma-associated antigen; IL-2; IFN.gamma.; IL-4; GMCSF; IL-12; B7; erb-B-2 and carcinoembryonic antigen. The recombinant viruses and gene products therefrom are useful for cancer therapy.