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Results for “SILICON COMPOUNDS”

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At least 19 recordsLinked to original sources
PubMed1995

Kinetic study of release of silicon compounds from polysiloxane tissue expanders.

The release behavior of typical commercial tissue expanders has been examined by carrying out two kinds of experiments: 1) Determination of chemical nature and its modification after in vivo use by X-ray photoelectron spectroscopy for chemical analysis. This study has been paralleled by scanning electron microscopy with associated energy dispersive X-ray analysis of surface, as well as by silicon compounds analysis of tissues around implants. 2) Kinetic examination of silicon compounds released by the biomaterial in physiologic solution at 36 +/- 0.3 degrees C. Results of these investigations have shown independently that the starting material was not a filler-free, pure polymer, but a composite, reinforced elastomer, with the reinforcing agent most seemingly represented by silicon dioxide. Release of latter, with a relatively fast kinetics, is compatible with data of the simulating laboratory runs in the physiologic solution. All these facts seem to rule out any hypothesis of a prevailing siloxane oligomer migration. The correlation of kinetic and physicochemical tests with the in vivo behavior is discussed.

Chemical Phenomena↗
PubMed1984

Silicon compounds as substrates and inhibitors of acetylcholinesterase.

Several trimethylsilyl derivatives were found to be ligands of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7): trimethylsilylethyl acetate (III) and trimethylsilylmethyl acetate (V) are substrates of the enzyme, whereas trimethylsilylethanol (VIII) is a competitive inhibitor. The silicon compounds have kinetic parameters similar to those of their carbon analogues, except for trimethylsilylmethyl acetate, which is a substrate of acetylcholinesterase, whereas its carbon analogue is not susceptible to enzymic hydrolysis.

Binding, Competitive↗
PubMedDate not supplied

[The balneotherapy importance of the silicon compounds in siliciferous waters when used externally].

Bath therapy was assigned to 300 patients with primary hypothyroidism, chronic venous insufficiency of the legs, neurologic symptoms of lumbar osteochondrosis. Fresh, siliceous, siliceous carbon-dioxide and carbon-dioxide waters were tested comparatively. It is reported that siliceous baths with threshold silicon compounds concentration 50 mg/l had the effect similar to that of fresh-water baths. Indications have been specified for introduction of carbon dioxide and siliceous carbon dioxide baths in the diseases studied.

Baths↗
PubMed1995

Wegener granulomatosis is associated to exposure to silicon compounds: a case-control study.

Wegener granulomatosis is a rare disease of unknown aetiology. In the majority of these patients the kidney is involved in the disease process. We performed a case-control study to evaluate the role of occupational exposure in the development of Wegener granulomatosis with renal involvement. The occupational histories of 16 cases with clearly established diagnosis of Wegener granulomatosis with renal involvement were compared with those of 32 age- and sex-matched controls. It was observed that inhalation of silicon-containing compounds such as silica and grain dust gave a nearly sevenfold risk for Wegener granulomatosis. Further epidemiological and experimental work needs to be performed in order to corroborate these findings.

Adult↗
PubMedDate not supplied

New silicon compounds as resistance modifiers against multidrug-resistant cancer cells.

The efficiency of chemotherapy is often decreased by the development of resistance of cancer cells to cytostatic drugs. This phenomenon is in most cases caused by the activity of the various ABC transporters, multidrug-resistance (MDR) gene-encoded p-glycoproteins, that pump anticancer drugs out of the cells. The inhibition of the activities of the MDR proteins MDR1 and MRP was investigated via the administration of two new organosilicon compounds, alis-409 and alis-421. The study was focused on the inhibition of MDR by blocking the ADR1 gene expression and through the inhibition of the pump-function of mdr-p-glycoprotein, in human breast cancer cell lines expressing mrp and prostate cancer cell line (PC-3). Apoptosis induction and the interaction between epirubicin and the silicon-substituted compounds were studied in human MDR-1 gene-transfected mouse lymphoma and its parent cell line, Colo320/MDR-LRP and sensitive subline Colo205, by means of rhodamine 123 accumulation. The activity of MRP1 p-glycoprotein was studied in human breast cancer cell lines such as HTB-26/MRP1 and two MRP-negative breast cancer cell lines, T47D and MCF7, by carboxyfluorescein accumulation, and on a stomach cancer cell line. The activity of MRP in 257P/MDR and its drug-sensitive derivative were studied in human stomach cancer cells by daunorubicin accumulation in a flow cytometer. The two representative organosilicon derivatives, alis-409 and alis-421, showed antiproliferative effects without apoptosis induction. The drug accumulation in the human MDR1 gene-transfected mouse lymphoma cells was increased without down-regulation of the MDR1 gene expression tested by RT-PCR assay. The rhodamine uptake was increased in L5178/MDR1 and Colo320/MDR1-LRP, but not drug-sensitive human breast cancer MCF-7 and T47D, and L5178 mouse lymphoma parent cells in the presence of alis-409 and alis-421. The MRP-mediated carboxyfluorescein accumulation in HTB-26/MRP human breast cancer cells and daunorubicin accumulation in human stomach cancer cells 257P/MDR were not modified by these alis compounds. A synergistic interaction between epirubicin and the silicon-substituted resistance modifiers was found only in MDR1-mediated MDR in the case of colo-320/MDR1-LRP cells and mouse lymphoma cells transfected with the human MDR1 gene. The results indicate that the organosilyl derivatives specifically act on MDR1 p-glycoprotein 170. The alis compounds act on pgp170 in a way which is similar to verapamil isomers.

Animals↗