Air drying as a preparatory factor in cytology: investigation of its influence on dye uptake and dye binding

Fluorescence lifetime imaging is able to recognize different hematopoietic precursors in unstained routine bone marrow films

Fluorescence lifetime imaging (FLIM) has been used in living cells to measure metabolic activity and demonstrate cell differentiation. The aim of this study was to investigate whether the FLIM technique could be able to demonstrate cell maturation during myelopoiesis and erythropoiesis in unlabeled routine bone marrow (BM) preparations. Air-dried, unstained smears of BM aspiration samples of 32 patients without BM disease and a normal morphology on May-Grünwald-Giemsa (MGG) stained smears entered the study. FLIM images were captured with a Zeiss LSM 780 NLO multiphoton microscope equipped with a Becker & Hickl SPC-830 TCSPC FLIM module and HPM-100-40 hybrid detector. The samples were irradiated by two-photon excitation at 800 nm with a titanium-sapphire laser of the LSM 780 NLO. FLIM images were compared with those obtained by autofluorescence high resolution imaging. FLIM images of unstained smears were highly contrasted. Different cell types could be easily recognized as they were similar to those seen in MGG stained preparations. Cytoplasm of cells from the erythroid lineage revealed relatively short fluorescence lifetimes due to the presence of hemoglobin, and therefore could easily be distinguished from granulocytic precursors. Nuclear fluorescence lifetimes of all cell types were higher than those of the corresponding cytoplasm. So, FLIM of unstained BM smears obtained under routine real-life conditions permits an easy identification of BM cells, by highlighting differences of their physicochemical properties.

Rapid staining techniques in cytopathology: a review and comparison of modified protocols for hematoxylin and eosin, Papanicolaou and Romanowsky stains

The objective of this study was to review and compare rapid protocols for fixation and staining of cytologic smears. We used fresh surgical specimens from dogs and horses to evaluate and modify, if necessary, previously described rapid staining protocols. Slides were wet-fixed, rehydrated or air-dried. Rapid Papanicolaou, hematoxylin and eosin (H&E), and Romanowsky stains were applied, including modification of Diff-Quick stain. The modified rapid staining protocols were simple to use and gave results within 5 minutes that were comparable to those obtained with traditional methods. Advantages of rehydrated vs wet-fixed smears included consistent preparations, a clean background, and equally good or superior nuclear detail.

Enhanced detection of live bacteria using a dendrimer thin film in an optical biosensor

Here we describe the detection of live Pseudomonas aeruginosa using a sensing film containing a fourth-generation hydroxy-terminated polyamidoamine (PAMAM) dendrimer (i.e., G4-OH) and SYTOX Green fluorescent nucleic acid stain. The films are configured on simple, disposable plastic coupons or optical fibers and are interrogated using a miniature fiber-optic spectrometer. SYTOX Green is generally considered a dead cell stain because it is not able to cross the membranes of live cells. In the presence of PAMAM-OH (G4-OH) in water, the bacterial cell becomes permeable to the SYTOX dye and the fluorescence is significantly enhanced. The fluorescence increases with the bacteria concentration, and the intensity at 5.4 x 10(7) cells mL(-1) is 350% higher than the liquid controls without PAMAM-OH. We also demonstrate that dendrimers stabilize the sensing film. After drying and desiccation, the SYTOX Green/PAMAM-OH films are still able to quantitatively detect P. aeruginosa in water. Incorporation of glucose into the SYTOX Green/ PAMAM-OH film may improve the homogeneity of the film and enhances the fluorescence signal an additional 11-25%.

Improving biological dyes and stains: quality testing versus standardization

This paper discusses the impact of both standardization and quality testing of dyes and stains in biology and medicine. After the brief review of why standardized dyes and strains are not presently available commercially, two types of testing and ways of improving dye quality are described. National or international organizations could be established to define standardization of dyes and stains. Standardization would be specifically defined as a list of physico-chemical parameters such as elaborated in this paper. Commercial batches of comparable quality may be labeled by the supplier as "standard dye," a procedure currently performed by the European Council for Clinical and Laboratory Standardization (ECCLS). Also recommended to improve dye quality is commercial dye testing by independent laboratories with subsequent certification for use. This sort of quality control is currently carried out in the United States by the Biological Stain Commission (BSC). The advantages and disadvantages of both techniques and the use of image analysis for the definition of standards are discussed. A combination of both the BSC testing protocols and the ECCLS standards should be established for extended quality control of biological dyes and stains.

Cytological detection of epithelial dysplasia in the oral mucosa using Feulgen-DNA-image cytometry

Cytological scrape material of the oral mucosa from 114 patients with epithelial dysplasia and with oral cancer was stained with the Feulgen-reaction and investigated with an image analyzer. The size and the integrated optical density of cell nuclei, and four chromatin texture features were measured. All tumor slides contained cell nuclei with DNA greater than 5c, 16% of the slides had cell nuclei with DNA greater than 8c. A total of 14.5% of the tumor patients showed significantly increased DNA values in nuclei distant from the tumor. Two smears with severe epithelial dysplasia showed nuclei with DNA greater than 5c both in the tumor material and far from the tumor. Texture analysis allowed discrimination between benign, dysplastic and malignant smears. No correlation was found between DNA content and tumor staging. Image cytometry was a reliable method for detecting tumor cells. Epithelial dysplasia in areas distant from the tumor is probably due to "field canceration" of the epithelium.

Standardization of biological dyes and stains: pitfalls and possibilities

The present paper gives a review of the actual state of standardization of biological dyes and stains. In a first part general information is given on practical problems encountered by the routine user of dyes with special emphasis on dye contamination. Some theoretical aspects of standardization are discussed. The second part of the paper gives more detailed information on commercial batches of hematoxylin-eosin-, Giemsa- and Papanicolaou-stains and on their standardization. Special problems arising with the application of image analysis techniques are briefly mentioned. User-oriented specifications for the standardization of dyes, stains and staining procedures are given. Fluorescent dyes and dyes used in chromogenic reagents such as the Feulgen-Schiff reaction are not included in this review.

Silver staining of interphase nucleolar organizer regions in cytologic smears previously stained by the Papanicolaou and May-Grünwald-Giemsa techniques

Malignant cells are known to display a distinctive argyrophilic nucleolar organizer region (Ag-NOR) protein distribution compared with distribution in their benign counterparts. In this study, Ag-NOR staining was applied to smears from reactive and malignant serous effusions. The smears were either unstained or had been previously stained with the Papanicolaou or May-Grünwald-Giemsa (MGG) technique. The purpose of this study was to assess the feasibility and usefulness of Ag-NOR staining in diagnostic cytopathology and to set up a procedure that could be used on prestained smears in retrospective studies. The one-step silver staining method was applied to prestained smears after a weak destaining step in trichloracetic acid and to unstained smears after a postfixation step in Carnoy's fluid. Positive results were observed on both destained and unstained preparations, MGG-stained smears showing a better visualization of the silver deposits than Papanicolaou-stained smears. Major differences in size, shape, and distribution patterns of the Ag-NOR-positive granules were observed between neoplastic and reactive cells. Furthermore, the mean number of silver-stained dots per cell was significantly higher in malignant cells (33.32 +/- 2.23) than in reactive mesothelial cells (9.71 +/- 0.66). These data indicate that this Ag-NOR technique can be profitably applied to prestained cytologic smears to assist in the diagnosis of malignancy and that the technique has the advantage that cellular morphology and silver staining can be evaluated on the same slide.

The influence of the wet-fixed Papanicolaou and the air-dried Giemsa techniques on nuclear parameters in breast cancer cytology: a cytomorphometric study

The influence of fixation and staining on morphometric nuclear parameters in cytologic samples of breast lesions has been investigated with respect to the wet-fix and the air-dry techniques. Aspiration biopsy material from 55 benign and malignant breast lesions was smeared onto slides and stained with a routine Papanicolaou technique (after wet fixation) or with the Azur B-eosin Y stain (after air drying). Tumors were grouped according to both histological grade and lymph node status. Nuclear area, diameter, and perimeter were measured from each specimen with an image analyzer and correlated to grade and stage of the disease. All nuclear parameters were significantly smaller in wet-fixed slides. The coefficient of variation was smaller in air-dried samples, which allowed better discrimination between different groups. Nuclear perimeter had the highest discriminative power. Unintentional air drying in wet-fixed smears increased the coefficient of variation for all nuclear parameters. Air drying of cytologic smears is recommended for morphometric investigations if chromatin texture is of minor importance.