Debary'omvces hansenii was isolated from a cystic lesion in the distal tibia of a healthy 23-year-old woman. Ascospores were demonstrated when the organism was incubated at 25 but not at 30°C. Electron microscopy was necessary to demonstrate the warty surface of the ascospore wall. Growth was inhibited in vitro by low concentrations of amphotericin B, 5-fluorocytosine, miconazole, and ketoconazole. Four previous cases of infection caused by Debaryomnvces spp. and one caused by the related fungus Toruilopsis candida were reviewed.

Backscattered Electron Imaging (BEI) is a particular technique which permits to study cytochemical reactions with the Scanning Electron Microscope (SEM). The BEI data pertaining to specific enzymatic activities can be directly correlated to the surface morphology of each individual cell. Leukocytes from 5 normal individuals, 14 patients with acute nonlymphoblastic leukaemia (ANLL), 7 patients with chronic myeloid leukaemia (CML) and 3 patients with acute lymphoblastic leukaemia (ALL) were studied for myeloperoxidase activity, acid phosphatase localization, silver staining of the nuclei and phagocytosis of iron carbonyl in the BEI mode of SEM. Some normal peripheral blood leukocytes which cannot be distinguished by their surface morphology alone were satisfactorily identified with the BEI technique. Leukaemic myeloid cells can be recognized in many cases because of their positive myeloperoxidase reaction, while monocytic elements can be characterized by the presence of surface ruffles, acid phosphatase activity and active phagocytosis. The usefulness of the BEI technique in identifying different blood cell types with the SEM and its possible application to the diagnosis of certain cases of leukaemia are discussed.

White blood cells have been studied in the back-scattered electron imaging (BEI) mode of scanning electron microscopy (SEM) with cytochemical methods for endogenous peroxidase, acid phosphatase, and a silver-staining method for nuclei. Peroxidase-positive granules were seen with good contrast and resolution in myeloid precursor cells and acid phosphatase activity was easily detected in macrophages and monoblasts. Silver staining permitted recognition of the shapes and location of the nuclei. In spite of the cytochemical procedures, cell surface structures were reasonably well-preserved in all methods, making direct correlation of BEI and secondary electron imaging (SEI) images an attractive feature in cell research with the scanning electron microscope.

The solid-phase immune electron microscopy-double-antibody technique, which takes less than 1 h to perform, was applied as a rapid, sensitive, and specific diagnostic tool in the demonstration of papovavirus particles. BK virus propagated in 82C human skin fibroblasts and a monospecific high-titer immune serum to BK virus were used to establish the test procedure. When Formvar-carbon-coated grids were treated with appropriately diluted antibody, a 28-fold increase of virus particles per square micrometer was observed. Viewing of the virus particles was facilitated by the addition of a second "decorator" antibody. BK virus preparations at concentrations of 10(2) to 10(3) PFU/ml could be detected by this technique. There was no cross-reaction with mouse polyomavirus.

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