PubMed · 13669458
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P P FIGDOR. 1959-05-15. Rational electrolyte therapy.. https://pubmed.ncbi.nlm.nih.gov/13669458/
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The aim of this work was to study the influence of the phosphorus on the crystallization and bioactivity of glass-ceramics obtained from sol-gel glasses. For this purpose two sol-gel glasses with a similar composition but one of them containing P2O5 (70% SiO2; 30% CaO and 70% SiO2; 26% CaO; 4% P2O5, mol%) were prepared. Pieces of these glasses were treated at temperatures ranging between 700 degrees C and 1400 degrees C for 3 h. The obtained materials were characterized by XRD, FTIR, SEM-EDS and the biaxial flexural strength was determined in samples heated at 1100 degrees C. In addition, an in vitro bioactivity study in simulated body fluid (SBF) was carried out. The results showed that phosphorus plays an important role in the crystallization of the glasses: it induced the crystallization of calcium phosphate phases, the stabilization of the wollastonite phase at high temperature as well as the crystallization of SiO2 phases at low temperatures. Moreover, the presence of phosphorus produced a heterogeneous distribution of defects in the pieces and, therefore, the flexural strength of samples containing this element decreased. Finally, glass-ceramics obtained from glasses containing phosphorus showed the fastest formation rate of the apatite layer when soaked in SBF.
The native extracellular matrix (ECM) laid down on silicon and titanium surfaces by osteoblast-like SAOS-2 cells was exposed by selective removal of cells. This type of material surface ECM-Si, ECM-Ti was shown to promote the nucleation of calcium phosphate from a simulated body fluid (SBF). Microscopic and spectroscopic results revealed the effect was associated with a collagen fiber-free extracellular matrix.
The use of a monolithic column (Chromolith, SpeedROD RP-18e, by Merck) was studied on the determination of cephalosporin antibiotics. Results were compared with those from a previously developed analytical method using conventional silica-based analytical column. A rapid, accurate and sensitive method has been developed and validated for the quantitative simultaneous determination of four cephalosporins: Cephalexine and Cephadroxil (first generation), Cefaclor (second generation) and Cefotaxim (third generation) in pharmaceuticals as well as in human blood serum and urine. Hydroflumethiazide (HFM) (3,4-dihydro-6(trifluoromethyl)-2H-1,2,4-benzothiadiazine-7-sulfonamide-1,1-dioxide) was used as an internal standard at a concentration of 1.5 ng/microL. A rectilinear relationship was observed up to 5 ng/microL for the four compounds. Analysis time was less than 4 min. The statistical evaluation of the method was examined by means of within-day repeatability (n=8) and day-to-day precision (n=8) and was found to be satisfactory with high accuracy and precision results. The method was applied to the determination of the cephalosporins in commercial pharmaceuticals and in biological fluids: human blood serum after solid phase extraction and urine simply after filtration and dilution. Recovery of analytes in spiked serum samples was in the range from 88.7 to 107.8%, while for urine samples recovery was from 98.0 to 105.6%. By comparing the figures of merit for the monolithic column and the silica-based one, regarding the determination of the four cephalosporins investigated in the present study, the outstanding efficiency of the monolithic column can be noticed.