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Inhalation Toxicity of Metal Particles and Vapors
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Osmium, the most dense metal, is used in metal alloys with iridium in instrument pivots, compass needles, electrical contacts, and engraving tools. Until 1969, two osmium alloys were used as fountain pen tips. Academic and research laboratories are the major users of osmium. Osmium tetroxide is used as a tissue stain for histological preparations.
Immunohistochemistry of the Pulmonary Extracellular Matrix
Published in Joan Gil, Models of Lung Disease, 2020
Antonio Martinez-Hernandez, Peter S. Amenta
The DAB deposited in the tissues lacks electron density; however, it is highly osmiophilic. Therefore, incubation with OsO4 results in DAB-OsO4 complexes suitable for electron microscopy. Following DAB incubation and a PBS wash, the sections are reacted with 1% osmium tetroxide in 0.1 M sodium phosphate buffer with 0.026 M NaCl, at pH 7.2, for 1 hr at room temperature. Osmium tetroxide vapors are toxic, particularly to corneal tissues: care should be taken to work under a chemical hood. An ampule of osmium tetroxide (1 g/vial) is broken inside a tightly stoppered brown glass bottle and dissolved in 50 ml of distilled water (2%). Complete solubilization may take 24 hr, but it may be accelerated by placing the tightly stoppered bottle in a sonicator bath. This 2% aqueous OsO4 solution is diluted 1:1 with 0.2 M sodium phosphate buffer containing 0.026 NaCl (pH 7.2) immediately before use.
Autoradiography
Published in Howard J. Glenn, Lelio G. Colombetti, Biologic Applications of Radiotracers, 2019
Sven Ullberg, Bengt Larsson, Hans Tjälve
As electron microscopic autoradiography has so far not been successfully carried out for localization of soluble compounds, a traditional technique for preparation of ultra-thin sections can be used. A small tissue piece can, for instance, be fixed in glutaraldehyde and osmium tetroxide. It can then be dehydrated and embedded in resins. Sections in the range of 0.1 μm (100 nm) can be taken on a water surface using an ultrotome equipped with a glass knife. The sections may be stained with uranyl acetate and/or lead citrate before emulsion application. It is then advisable to evaporate a thin layer of carbon over the section as a protection of the emulsion from chemography. (The staining may alternatively be postponed until after exposure, in which case the carbon should be omitted since it prevents the penetration of the stains.)
Membrane protective role of autophagic machinery during infection of epithelial cells by Candida albicans
Published in Gut Microbes, 2022
Pierre Lapaquette, Amandine Ducreux, Louise Basmaciyan, Tracy Paradis, Fabienne Bon, Amandine Bataille, Pascale Winckler, Bernhard Hube, Christophe d’Enfert, Audrey Esclatine, Elisabeth Dubus, Marie-Agnès Bringer, Etienne Morel, Frédéric Dalle
Experiments were carried out in the CellImaP core facility. Cells (HeLa or HCT116), grown on Thermanox coverslips, were fixed for 1 h at 4°C in 4% paraformaldehyde and 2.5% of glutaraldehyde in Sorensen phosphate buffer (0.1 mM, pH 7,3). After fixation, samples were washed by Sorensen phosphate buffer. The postfixation treatment was realized with 1% osmium tetroxide at RT for 1 h. Dehydration and resin impregnation of the samples were performed manually: dehydration was done by increasing degrees of ethyl alcohol (50°, 70°, 95°, and 100°) and substitution was done by three absolute ethanol: Embed-812 resin mixtures and impregnation in Embed-812 resin. The polymerization of samples was performed with a mixture Embed-812: 3% BDMA in the gelatin capsule maintained for 48 h at 60°C. Blocks were cut on an ultramicrotome, and slices (thickness of 60 nm) were deposited on copper/palladium grids. After drying, grids were contrasted with uranyl acetate and lead citrate. TEM observations of cells were realized at the Dimacell imaging facility (Dijon, France) on a HITACHI H-7500 operating at 80 kV.
Subepithelial deposits with microspherular structures in membranous glomerulonephritis
Published in Ultrastructural Pathology, 2022
Hae Yoon Grace Choung, Jerome Jean-Gilles, Bruce Goldman
Tissue submitted for electron microscopy was fixed in 2.5% glutaraldehyde in Millonig’s buffer, then washed in Millonig’s buffer for five (5) minutes, and post-fixed in 1% osmium tetroxide in Millonig’s buffer for 20–30 minutes. Dehydration of tissue was done as follows: 25% ethyl alcohol, 5 minutes; 50% ethyl alcohol, 7 minutes; 75% ethyl alcohol, 10 minutes; 95% ethyl alcohol 15 minutes; 100% ethyl alcohol, 30 minutes × 3 changes; 100% + propylene oxide, 30 minutes (1:1 ratio); propylene oxide, 20 minutes × 2 changes; and P.O. + Eponate 12- araldite 502, 60 minutes (1:1 ratio – cap off). The specimen was then embedded in epoxy resin and sectioned using standard techniques. Toluidine blue sections were used for selection of appropriate areas for thin section preparations. All renal compartments were carefully examined under a Hitachi HT 7800. Selected photographs were then taken and stored in an encrypted electronic folder.
Amelioration of renal cortex histological alterations by aqueous garlic extract in gentamicin induced renal toxicity in albino rats: a histological and immunohistochemical study
Published in Alexandria Journal of Medicine, 2021
Hala ZE Mohamed, Merry BK Shenouda
Renal cortex tissue was cut into 1 mm3 pieces and fixed in 2.5% buffered glutaraldehyde for 24 hours. These were washed in three changes of cacodylate buffer (pH 7.2) for 20 minutes in each change. Specimens were postfixed in osmium tetroxide. Dehydration of specimens was done using ascending grades of ethyl alcohol. Embedding was accomplished in Epon 812. Semithin sections of 1 μm in thickness were cut, stained with toluidine blue, examined and photographed. From selected regions, ultrathin sections were cut at 50–80 nm in thickness and were placed on copper grids. They were stained using uranyl acetate and lead citrate. They were examined by transmission electron microscopy (Jeol- JEM- 100 CXII; Jeol, Tokyo, Japan) and photographed in the Assiut University Electron Microscopy Unit [20].