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At least 37 records · Page 2Linked to original sources
PubMed1977

[Studies on silicate-containing and silicate-free adhesives compared to composite materials II].

The photo-polymerisable adhesive Estilux glaze and its successor product Estiglaze microfill as well as a compound from the same firm were subjected to comparative investigations. Maximal polymerisable thickness of the named materials were ascertained by means of variable intensive light sources. Electron-microscopic investigations were carried out on the matrices in order to estimate the wetting behaviour. No generally valid connection between hardness and abrasion of comparative materials could be observed, but Estiglaze microfill, containing filling-substance shows reduced abrasiveness to the factor 2.5 in comparison to products free from filling substance.

Composite Resins↗
PubMed1996

Silicate antibodies in women with silicone breast implants: development of an assay for detection of humoral immunity.

Silicon, in the form of sodium silicate (Na2SiO3), adsorbed onto bovine serum albumin (BSA)-precoated plates served as the solid-phase antigen in an enzyme immunoassay to detect silicate-reactive antibodies in the plasma of 40 symptomatic women with silicone breast implants, 91 asymptomatic women with silicone breast implants, 50 healthy control women, and 52 women with rheumatic diseases and without silicone breast implants, Silicate-reactive antibodies of immunoglobulin G (IgG) or IgM isotypes were detected in the plasma of 30% (12 of 40) of the symptomatic women with silicone breast implants; 9% (8 of 91) of the asymptomatic women with silicone breast implants; 5% (1 of 20) of the women without implants who had systemic lupus erythematosus; and 0% (0 of 32) of the women without implants who had either Sjögren syndrome, scleroderma, or rheumatoid arthritis. Only 2% (1 of 50) of the sera from the healthy control women contained silicate-reactive antibodies. Preincubation of sera with silicate and eight other metal compounds (including SiO2) demonstrated that the IgG and IgM antibodies bound specifically to silicate, because preincubation with Na2SiO3 inhibited more than 90% of the activity, whereas CrO3, Li2SO4, MgSO4, NiSO4, HgCl2, ZrOCl2, BeSO4, and SiO2 failed to inhibit the IgG or IgM antibody binding to the silicate-BSA plates. Furthermore, the F(ab')2 portion and not the Fc portion of the silicate-reactive IgG was reactive with BSA-bound silicate in the enzyme immunoassay. The assay for silicate-reactive antibodies was quantified by assigning arbitrary units to a standard curve composed of serial twofold dilutions of high-positive (ten times higher than the cutoff) silicate antibody sera. This novel assay is a useful method for detecting and quantifying humoral immune response to silicate.

Antibody Formation↗
PubMed1987

Cytotoxicity of respirable dusts from industrial minerals: comparison of two naturally occurring and two man-made silicates.

The membranolytic and cytotoxic properties of two naturally occurring (chrysotile asbestos; attapulgite clay) and two man-made (Fiberfrax, an aluminium-silicate, and xonotlite, a calcium silicate) industrial minerals were compared. "Short" fiber fractions of chrysotile and Fiberfrax were obtained by sedimentation in demineralized water, while the attapulgite and xonotlite samples were used as obtained. The aluminium silicate fibers were found to be non- hemolytic, while for the other three silicates, chrysotile had the strongest hemolysis potential, followed very closely by xonotlite; attapulgite was less hemolytic than the former two silicates, but was nevertheless highly hemolytic to the rat erythrocytes. Using rat pulmonary alveolar macrophages, the in vitro cytotoxicity assays showed that with fresh cell monolayers, all four silicates were equivalent in causing cell damages at a dose of 250 micrograms; at a lower dose (50 micrograms), the intensity of the cytotoxic effect was in the decreasing order: Fiberfrax greater than attapulgite greater than chrysotile greater than xonotlite. With one day-old cultured cell monolayers, a dose of 250 micrograms of the silicates fibers was less cytotoxic, with the exception of the attapulgite fibers which remained essentially as cytotoxic as with the fresh cell monolayers. The reduced cytotoxic response was especially noticeable with the chrysotile fibers. At 50 micrograms, the cytotoxicity scale of the mineral dusts with one day-old cell monolayers was essentially the same as the one obtained with the fresh cell monolayers, that is: Fiberfrax approximately equal to attapulgite greater than chrysotile greater than or equal to xonotlite. Overall, these in vitro tests imply: 1) that all four industrial silicates tested can be considered to be "biologically active"; 2) that on the basis of their different reactivities with the two types of cell culture conditions used, their biological reactivity in vivo might be quite distinct. This might be especially true for at least the chrysotile, attapulgite and xonotlite short fibers, considering that these three types of silicate dusts have very similar dimensions. Moreover, for the chrysotile and attapulgite samples, fiber numbers is probably not an important factor, since the density of the two silicates is roughly the same. The unaltered cytotoxic responses of the American attapulgite fibers in the two macrophage assays correlate well with the fact that short attapulgite fibers seems to have a stronger in vivo reactivity than short chrysotile fibers. In fact, it might be the strongest of the four industrial silicates tested.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗