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Results for “Silicic Acid”

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At least 19 recordsLinked to original sources
PubMed1987

Interrelationship between hemolysis and lipid peroxidation of human erythrocytes induced by silicic acid and silicate dusts.

Silicic acid and silicate dusts (slate dust and chrysotile asbestos) cause hemolysis of erythrocytes in vitro. The peroxidation of polyunsaturated fatty acids (PUFA) of erythrocyte membrane lipids is also enhanced by incubating the erythrocytes with silicic acid and silicate dusts in in vitro. Hemolysis of erythrocytes elicited by silicic acid and silicate dusts is inhibited significantly by polyvinyl-pyrrolidone and dipalmitoyl lecithin (DPL). These agents, however, have no effect on silicic acid and silicate dust induced peroxidation of erythrocyte membrane lipids. On the other hand, peroxidation of erythrocyte membrane lipids, induced by silicic acid and silicate dusts, is inhibited almost completely by adding superoxide dismutase and catalase to the incubation system, whilst the hemolysis of erythrocytes induced by silicic acid and silicate dusts is unaffected by these agents. Similarly the lysis of erythrocytes, induced by silicic acid and silicate dusts, proceeds at a much faster rate than silicic acid and silicate dust induced lipid peroxidation. These results indicate that silicic acid and silicate dust induced hemolysis and lipid peroxidation represent two independent processes.

Asbestos↗
PubMed2001

Effect of some amino acids and peptides on silicic acid polymerization.

The polymerization of silicic acid in aqueous solutions at different pH was followed by the colorimetric molybdosilicate method. The role of four amino acids (serine, lysine, proline and aspartic acid) and the corresponding homopeptides was studied. All four amino acids behave the same way and favor the condensation of silicic acid. Peptides exhibit a stronger catalytic effect than amino acids but they appear to behave in very different ways depending on the nature of side-groups and pH. Poly-lysine and poly-proline for instance lead to the precipitation of solid phases containing both silica and peptides. The role of these biomolecules on the polymerization of silicic acid is discussed in terms of electrostatic interactions, hydrogen bonds and solubility.

Journal Article↗
PubMed2002

A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid.

Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.

Adsorption↗
PubMed1983

Binding of silicic acid by proteins and its relation to toxicity of silicate dusts.

A possible mechanism of biological effects of silicate dusts is the interaction between silicic acid and tissue constituents, and this has been studied in vitro. On incubating silicic acid with lung homogenate, appreciable amounts of silicon were recovered in the trichloroacetic acid precipitate in both organic solvent extract and residual protein. Polyvinyl pyrrolidone inhibited this interaction as well as reducing the dissolution of silicic acid from asbestos dust. The capacity of serum albumin to bind silicic acid was also observed. Chemical interaction between macromolecules and silicic acid could be one of the factors responsible for the biological effects of silicon-containing dusts.

Animals↗
PubMed1977

Chromatographic patterns of prostaglandins using different lots of silicic acid.

The chromatographic patterns of prostaglandin E2 chromatographed on various lots of silicic acid are presented. Two lots of Mallinckrodt silicic acid tested give totally unsatisfactory separation of PGE2. Sigma silicic acid SIL-R gives better separation than any of the Mallinckrodt lots tested. Increasing the size of the "E" fraction of solvent can give satisfactory separation on Mallinckrodt silicic acid.

Chromatography↗
PubMed2005

Arginine kinase in the demosponge Suberites domuncula: regulation of its expression and catalytic activity by silicic acid.

In Demospongiae (phylum Porifera) the formation of the siliceous skeleton, composed of spicules, is an energetically expensive reaction. The present study demonstrates that primmorphs from the demosponge Suberites domuncula express the gene for arginine kinase after exposure to exogenous silicic acid. The deduced sponge arginine kinase sequence displays the two characteristic domains of the ATP:guanido phosphotransferases; it can be grouped to the 'usual' mono-domain 40 kDa guanidino kinases (arginine kinases). Phylogenetic studies indicate that the metazoan guanidino kinases evolved from this ancestral sponge enzyme; among them are also the 'unusual' two-domain 80 kDa guanidino kinases. The high expression level of the arginine kinase gene was already measurable 1 day after addition of silicic acid by northern blot, as well as by in situ hybridization analysis. Parallel determinations of enzyme activity confirmed that high levels of arginine kinase are present in primmorphs that had been exposed for 1-5 days to silicic acid. Finally, transmission electron-microscopical studies showed that primmorphs containing high levels of arginine kinase also produce siliceous spicules. These data highlight that silicic acid is an inorganic morphogenetic factor that induces the expression of the arginine kinase, which in turn probably catalyzes the reversible transfer of high-energy phosphoryl groups.

Amino Acid Sequence↗
PubMed1982

Electron micrographic study of precipitates formed by interaction of silicic acid and alkaline phosphatase: contribution to a study of silica urolithiasis in cattle.

Association of alkaline phosphatase with silicic acid in precipitates formed in dilute solution was studied as a model for the nonspecific reaction between silicic acid and protein. Precipitates contained 68-83% of the silicic acid and 52-83% of the enzyme in the original mixture and were in the form of aggregates of roundish particles 150-800 nm in diameter. Enzyme protein formed a tightly bound layer on the surface of particles formed in solutions of freshly prepared silicic acid. The similarity between the ultrastructural features of precipitates from solutions of silicic acid and of internal portions of siliceous urinary calculi from cattle suggests that deposition of silica during development of such calculi is due, at least in part, to the interaction of protein with silicic acid in urine.

Acid Phosphatase↗
PubMedDate not supplied

The role of silicic acid in the renal excretion of aluminium.

The chemical affinity of silicic acid for aluminium (AI) has been shown to reduce the bioavailability of AI in studies of human gastrointestinal (GI) absorption. Investigations were carried out to ascertain whether or not similar interactions may also enhance the renal excretion of AI by assessing the urinary output of both elements. Healthy individuals given monosilicic acid as naturally found in beer, excreted the majority of the silicic acid content (mean 56 percent) within 8 hours, concomitant with a significant increase in AI excretion (P < 0.05). Ingestion of increasing doses of silicic acid resulted in dose related increases in excretion of Si. Excretion of AI reached a maximum and then declined, consistent with depletion of AI body stores. This was confirmed using the 26AI isotope. The low serum but high urine concentration of Si suggests that if AI and Si interact to form an excretable species they do so in the kidney lumen such that Si limits the reabsorption of AI. Silicic acid's effect on the depletion of aluminium stores and reduced GI absorption suggest its addition to municipal water supplies may be a low risk public health measure to reduce the AI burden in the general population.

Aluminum↗