The reaction of Acridine Orange with proteoglycans in the articular cartilage of the rat

Abstract

Acridine Orange in concentrations from 0.01% to 0.2% was added to the first fixative solution in order to stain vibratome sections and small blocks of the articular cartilage of 2 month old rats. The interterritorial matrix of the radial or deep zone (zone 3) was examined. It contained reaction products with different morphology depending on the specimens used. In vibratome sections filaments were seen arranged in a homogenous pattern and changing in size with the concentration of the dye: diluted solutions produced finer filaments than concentrated ones. In contrast, in tissue blocks the staining pattern was not altered by different concentrations of Acridine Orange. However, with increase of the distance from the surface of the specimens the size of the filaments gradually decreased and formed a finer network. Since after preincubation with chondroitin ABC lyase only minute reaction products remained, an interaction of the dye with the sulphated glycosaminoglycans of the proteoglycans in the articular cartilage is suggested. The experiments show that by using mainly monocationic monomers of Acridine Orange the proteoglycans can be stained in a more expanded state than with polycationic dye polymers.

Acidic cysteine endoproteinase cathepsin K in the degeneration of the superficial articular hyaline cartilage in osteoarthritis

“…For in situ pH measurement with an acridine orange fluorescent probe, sections were treated with ferriammonium sulfate for 15 minutes, rinsed in distilled water, and stained with 1 mg/ml of acridine orange (catalog no. A‐6014; Sigma, St. Louis, MO) for 1.5 minutes (17). For purposes of comparison, some sections from grade 0 samples were balanced to different pH values by a 3‐day incubation at pH 4.0–8.0 (acetate buffer for pH 4.0 and 5.0, phosphate buffer for pH 6.0, 7.0, and 8.0, and citrate buffer for pH 4.0, 5.0, 6.0, 7.0, and 8.0).…”

Cell surface expression of 27C7 by neonatal rat olfactory ensheathing cells in situ and in vitro is independent of axonal contact

“…Frontal sections (12 m) were cut with a cryostat and mounted onto poly-L-lysine-coated object slides. For semithin sectioning, tissue was Wxed with glutaraldehyde (2.5%) in sodium cacodylate (0.1 M, pH 7.3) and osmium tetroxide (2% in sodium cacodylate, 0.1 M) and embedded in Epon (Brandes and Reale 1990;Wewetzer et al 2005). Semithin sections (0.5 m) were cut using an Ultracut E (Reichert-Jung, Wetzlar, Germany) and stained with toluidine blue.…”

The proteoglycan skeleton of the Kurloff body as evidenced by Cuprolinic Blue staining

“…The elongated shape of collagen-associated proteoglycans is also preserved with solutions of the monocationic dye Acridine Orange (reviewed in Brandes & Reale, 1990), or after CPC-precipitation (Malchiodi Albedi et al, 1988) and is well correlated to data from rotary shadowing (Iozzo et al, 1982). Moreover, following high-pressure freezing, freeze substitution and low-temperature embedding, which is assumed to preserve proteoglycans 'in their native extended state', cartilage proteoglycans appear as a 'reticular network' of 'threads' (Hunziker & Schenk, 1987).…”