Proton pump inhibitors control osteoclastic resorption of calcium phosphate implants and stimulate increased local reparative bone growth.

Calcium phosphate (CAP) rods and pastes based on dicalcium and tetracalcium phosphate chemistry were modified with a specific osteoclast proton pump inhibitor, Bafilomycin A(1), and implanted in the distal femurs of young male Wistar rats for 7, 10, and 14 days. The extent of osteoclastic resorption of these materials and the amount of regenerative bone formed were qualitatively evaluated. Resorptive activity similar to the remodeling process of natural bone was observed in the controls. In contrast, the resorption of materials containing Bafilomycin A(1) was considerably lower, even though tartrate-resistant acid phosphatase-positive osteoclasts were present at the tissue/material interface. A greater amount of newly formed bone consistently surrounded the CAP rods and pastes containing Bafilomycin A(1) in comparison to the control specimens, which indicated that this reparative bone was not resorbed as quickly as the new bone surrounding the controls. Increased local bone mass around the Bafilomycin A(1)-modified materials resulted from the diffusion of the proton pump inhibitor into the biological tissue at the defect site. Thus, through inhibition of the osteoclast proton pump, Bafilomycin A(1) slowed down not only the resorption of the implant material but also the resorption of the newly formed reparative bone, which resulted in an increased local bone mass.

Transport of organic dyes through ether-type polyurethane membrane.

Transport of various anthraquinone, acidic and basic dyes in aqueous solution through ether-type polyurethane membrane has been studied to better define the factors affecting the removal of organic compounds by the polyurethane membrane and to complement the previously proposed sorption mechanism. The effects of pH, salts, dye geometry and size, initial dye concentration, thickness of the membrane, and solution temperature on the rate of transport were investigated. Transport was found to be dependent upon the pH conditions of the starting and the receiving solutions. An increased rate of transport was observed with increased solution temperature and with the use of a thinner polyurethane membrane. The differences in the rates of transport can be attributed to the relative solubility of the organic dyes in the membrane and in solution, and to the strength and extent of intermolecular interactions with the polymer. Dye concentration, geometry and size, and the presence of salts in solution had no significant effect on the rate of transport. All of the studied dyes were found to exist as neutral species in the membrane.

Extraction of phenols using polyurethane membrane.

The extraction of various phenols from aqueous and organic solutions using polyurethane membrane has been investigated. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. The phenols are extracted as neutral species and the extraction is governed by a combined effect of intra- and intermolecular hydrogen bonding and nonspecific hydrophobic interactions. The ether-type membrane showed higher extraction capability for the phenols than the ester-type polyurethane membrane.

An investigation into the sorption of benzoic acids by polyurethane membrane.

The extraction mechanism of organic compounds by ether- and ester-type polyurethane membrane has been investigated through a detailed study of sorption of monobromobenzoic acids. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. It was found that monobromobenzoic acids are extracted in their neutral form, and that the extraction is controlled primarily by the relative strength of intra- and intermolecular hydrogen bonding. The ether-type polyurethane membrane allows a more efficient removal of monobromobenzoic acids from solution than the ester-type membrane. The extraction of benzoic acids with the ether-type membrane decreases as the temperature increases. When the ester-type polyurethane membrane is used, an extraction maximum is observed at room temperature with a decrease in extraction at lower and higher temperatures.

[Chlamydia trachomatis in imminent premature deliveries]. / Chlamydia trachomatis w zagrazajacych porodach przedwczesnych.

In the period od February-August 1995 fifty-two pregnant women treated for imminent premature deliveries were tested. Among 18 of them (34.6%) presence of chlamydial antibodies were found. The premature rupture of membranes occurred in 19.2% of women with positive Ch. trachomatis test results (p < 0.05).