The microassay of hyaluronic acid concentration and hyaluronidase activity by capillary turbidity (CT) and capillary turbidity reduction (CTR) tests

An Improved Assay for the N-Acetyl--glucosamine Reducing Ends of Polysaccharides in the Presence of Proteins

Hyaluronan concentration and hyaluronidase activity can be assayed by using different techniques including turbidimetry, viscosimetry, ELISA, chromatography, and colorimetry. The most popular colorimetric method is that of J. Reissig et al. (1955, J. Biol. Chem. 217, 959-966), in which the color results from a reaction between the Ehrlich's reagent (DMAB) and the N-acetyl-d-glucosamine reducing end of each hyaluronan chain. Nevertheless, there are problems with this method when proteins are present in the medium. Here we propose a new interpretation of the Reissig signal for estimating such reducing ends in media containing enzymes or other proteins. This interpretation is based on the fact that the absorbance obtained by using the Reissig method results from two factors: a turbidity due to the formation of polysaccharide-protein complexes and a color resulting from the action of DMAB on the reducing end of the polysaccharide chains. The turbidity at 585 nm, the wavelength at which the color intensity is maximal, may be estimated by curve fitting the spectrum between 450 and 650 nm. Subtracting the turbidity from the absorbance gives the colorimetric intensity which represents the concentration of polysaccharide chains. Moreover, the turbidity may give additional information about the existence of polysaccharide-protein complexes and their nature.

Binding of glycosaminoglycans to the surface of Treponema pallidum and subsequent effects on complement interactions between antigen and antibody

Acidified bovine serum albumin (acid BSA) reacts with glycosaminoglycans to form a precipitate. This reaction was adapted to Treponema pallidum to show glycosaminoglycans associated with the surface of the micro-organism. As testicular infection progressed from days 4 to 18, treponemes showed increasing amounts of these surface components. High speed centrifuging effectively removed the glycosaminoglycans, thus indicating that they were loosely bound. The subsequent addition of commercial preparations of hyaluronic acid or chondroitin sulphate resulted in their immediate adherence to the surface of the pathogens T pallidum and T pertenue, but not to the non-pathogens T vincenti, T denticola, or T phagedenis. The amount adhering to the treponemal surface varied depending on the concentration added. Intradermal inoculation showed that the virulence of T pallidum was not altered by the glycosaminoglycans associated with its surface. The coating of treponemes with hyaluronic acid or chondroitin sulphate did not interfere with neutralising antibodies or antibodies found by radioimmunoassay using whole organisms. In contrast, hyaluronic acid or chondroitin sulphate on the treponemal surface did interfere with immobilising antibodies. Results are discussed in terms of the potential role of the treponemal glycosaminoglycans in the infectious process.

Surfactants identified in synovial fluid and their ability to act as boundary lubricants

Thin-layer chromatography has been used to identify phospholipids extracted from canine synovial fluid, the major component (45%) being phosphatidyl choline (PC). The extracts and their components have been shown to be surface active in reducing the surface tension of water and to be readily adsorbed to hydrophilic solids, whose surfaces then become hydrophobic. These adsorbed monolayers of synovial surfactant were then found to be excellent boundary lubricants in vitro, reducing the coefficient of kinetic friction (mu) in the dry state and under physiological loading by up to 97% for extracts and 99% for PC alone, reaching mu = 0.01. Surface-active phospholipid is put forward as the possible active ingredient in joint lubrication and shown to be consistent with previous biochemical studies to elucidate its identity. The model essentially follows the classical Hardy model for boundary lubrication imparted by surfactants. It is discussed in relation to a new approach in providing artificial lubrication and facilitating tissue release in patients with arthritis.

Attachment of Treponema denticola to cultured human epithelial cells

The present electron microscopic study visualizes adherence of Treponema denticola, the most common treponeme of the gingival crevice in man, to human epithelial cells in vitro. The number of organisms adhering to the cells increased with increase in the treponemal concentration from 10(6) cells/ml through 10(8) cells/ml. Epithelial cells immediately after mitosis were particularly rich in treponemes. The number of adsorbing treponemes was reduced after pretreatment of the epithelial cells with hyaluronidase. The epithelial cells showed no predilection site of treponemal attachment. Treponemes attached preferably by their ends. Intracellularity of treponemes was not regularly attained. Treatment with ruthenium red, acidic bovine albumin or hyaluronidase indicted presence of acidic mucopolysaccharides on the treponemal and epithelial cell surface.

Detection of circulating immune complexes in the sera of rabbits with experimental syphilis: possible role in immunoregulation

The in vivo and in vitro immunoglobulin G plaque-forming cell responses to sheep erythrocytes (SRBC) are nearly obliterated during disseminated syphilitic infection (3 to 8 weeks post-intravenous injection) in rabbits. Splenic and lymph node cells obtained from infected rabbits during this time period were capable of suppressing the normal in vitro responses of uninfected, SRBC-primed cells. Cell-free washings of cells from infected animals were also suppressive. This finding coupled with the fact that treatment of infected cells with proteolytic enzymes abrogated the suppressive effect constitute arguments against involvement of a specific suppressor cell population. The incidence of elevated levels of circulating immune complexes in the sera of rabbits with disseminated disease was also significantly different from that of uninfected controls or infected rabbits before the onset or after the regression of lesions. When added to cultures of lymphocytes from uninfected, SRBC-sensitized rabbits, sera containing complexes caused dose-related suppression of the in vitro immunoglobulin responses. Unlike immune complexes, no correlation was found between the presence of mucopolysaccharide materials and the stage of infection or the ability of serum to suppress the immunoglobulin responses to SRBC.

Influence of testicular fluid infected with Treponema pallidum on intradermal lesions

A viscous mucoid fluid occasionally accumulates after intratesticular inoculation of rabbits with Treponema pallidum. Experiments were performed to assess the effects of this testicular fluid on the development of syphilitic lesions. Intramuscular injections of this fluid altered host defences as indicated by shorter incubation periods, by reactivation of healing lesions, and by the presence of lesions at a time when solid immunity should have developed.