UPLC-MS/MS Assay for Quantification of Wedelolactone and Demethylwedelolactone in Rat Plasma and the Application to a Preclinical Pharmacokinetic Study.

AIMS AND OBJECTIVE: Wedelolactone and demethylwedelolactone are the two major coumarin constituents of Herba Ecliptae. The objective of this work was to develop and validate a sensitive, rapid, and robust UPLC-MS/MS method for the simultaneous quantification of wedelolactone and demethylwedelolactone in rat plasma. MATERIALS AND METHODS: Wedelolactone and demethylwedelolactone were extracted from rat plasma by protein precipitation with acetonitrile. Electrospray ionization in negative mode and selected reaction monitoring (SRM) were used for wedelolactone and demethylwedelolactone at the transitions m/z 312.8→298.0 and m/z 299.1→270.6, respectively. Chromatographic separation was conducted on a Venusil C18 column (50 mm × 2.1 mm, 5 µm) with isocratic elution of acetonitrile-0.1% formic acid in water (55:45, v/v) at a flow rate of 0.3 mL/min. A linear range was observed over the concentration range of 0.25-100 ng/mL for wedelolactone and demethylwedelolactone. RESULTS: They reached their maximum plasma concentrations (Cmax, 74.9±13.4 ng/mL for wedelolactone and 41.3±9.57 ng/mL for demethylwedelolactone) at the peak time (Tmax) of 0.633 h and 0.800 h, respectively. The AUC0-t value of wedelolactone (260.8±141.8 ng h/mL) was higher than that of demethylwedelolactone (127.4±52.7 ng h/mL) by approximately 2-fold, whereas the terminal elimination half-life (t1/2) of wedelolactone (2.20±0.59 h) showed the approximately same as that of demethylwedelolactone (2.08±0.69 h). CONCLUSION: Based on full validation according to US FDA guidelines, this UPLC-MS/MS method was successfully applied to a pharmacokinetic study in rats.

[Clinical study on delayed flapless implants placement after bone powder grafted immediately in postextraction sockets].

PURPOSE: To explore and evaluate the clinical outcome of delayed flapless implant placements after bone powder grafted immediately in postextraction sockets. METHODS: 23 patient requiring dental implants after postextractions were selected for this study. The fresh sockets with at least 3 walls (3 or 4 walls) were immediately grafted and filled with artificial bone powders (Bio-oss and demineralized bone powders), covered by ultra-thin titanium membranes. Bone graft got to or 2-3mm higher than the top level of the sockets. 3 months later, the alveolar bone heights were checked by routine X-ray examination. And alveolar bone ridge widths were measured by bone-width gauges. The alveolar bones were confirmed sufficient to accommodate the implant with at least 4.0mm in diameter and 9mm in length. Then flapless implant placements were performed. The primary stability of the implants was measured. The implants were followed up and success rate of implant was evaluated. RESULT: The alveolar bone height and width were basically maintained without depression and atrophy through clinical observation and X-ray examination. Flapless implant placements were performed with minor local reaction. The primary stability of 36 implants all attained to 30N. Failure did not happen during a followed up period of by 6-62 months. CONCLUSION: After bone powder grafted immediately in postextraction sockets, sufficient alveolar bone volume for implants can be preserved. Flapless implant placements in sufficient bone support can effectively simplify the preoperative examination and surgical procedures, reducing local reaction. Delayed flapless implant placements after bone powder grafted immediately in postextraction sockets is an effective design and method of dental implantation.

Bioaccumulation versus adsorption of reactive dye by immobilized growing Aspergillus fumigatus beads.

The removal of reactive brilliant blue KN-R using growing Aspergillus fumigatus (abbr. A. fumigatus) immobilized on carboxymethylcellulose (CMC) beads with respect to initial dye concentration was investigated. Bioaccumulation was the dominant mechanism of the dye removal. According to the UV-vis spectra and the results of three sets of experiments, it could be concluded that the bioaccumulation using immobilized growing A. fumigatus beads was achieved by metabolism-dependent accumulation and metabolism-independent adsorption (15-23% proportion of overall dye removal), which included biosorption by mycelia entrapped in them and adsorption on immobilization matrix. The transmission electron microscope (TEM) images showed the intracellular structures of mycelia and the toxicity of dye. It was found that the fungus had a considerable tolerance to reactive brilliant blue KN-R at initial dye concentrations of <114.7 mg/l. Though at high initial dye concentrations the growth of mycelia was inhibited significantly by the dye molecules in the growth medium, the bioaccumulation capacity was not markedly affected and the maximum bioaccumulation capacity was 190.5+/-2.0 mg/g at an initial dye concentration of 374.4 mg/l. The bioaccumulation rates were not constant over the contact time.

Biosorption behavior of azo dye by inactive CMC immobilized Aspergillus fumigatus beads.

The biosorption equilibria and kinetics of an azo dye (reactive brilliant red K-2BP) were examined in this study using inactive carboxylmethylcellulose (CMC) immobilized Aspergillus fumigatus beads as the biosorbent. It was found that the biosorption capacity was at maximum when dye solution pH was about 2.0, that the sorption was spontaneous and endothermic with insignificant entropy changes, and that the Freundlich isotherm model fitted well to the biosorption equilibrium data. The biosorption rates were found to be consistent with a pseudo-second-order model. An intraparticle diffusion-based Weber-Morris model was applied to evaluate rate-limiting steps of the biosorption processes. The results suggested that the diffusion controlled the overall biosorption process, but the boundary layer diffusion of dye molecules could not be neglected. External mass transfer coefficients (beta(I)S) obtained by both Mathews and Weber model and Frusawa and Smith model were consistent.

Comparison of four supports for adsorption of reactive dyes by immobilized Aspergillus fumigatus beads.

Four materials, sodium carboxymethylcellulose (Na-CMC), sodium alginate (SA), polyvinyl alcohol (PVA), and chitosan (CTS), were prepared as supports for entrapping fungus Aspergillus fumigatus. The adsorption of synthetic dyes, Reactive Brilliant Blue KN-R, and Reactive Brilliant Red K-2BP, by these immobilized gel beads and plain gel beads was evaluated. The adsorption efficiencies of Reactive Brilliant Red K-2BP and Reactive Brilliant Blue KN-R by CTS immobilized beads were 89.1% and 93.5% in 12 h, respectively. The adsorption efficiency by Na-CMC immobilized beads was slightly lower than that of mycelial pellets. But the dye culture mediums were almost completely decolorized in 48 h using the above-mentioned two immobilized beads (exceeding 95%). The adsorption efficiency by SA immobilized beads exceeded 92% in 48 h. PVA-SA immobilized beads showed the lowest adsorption efficiency, which was 79.8% for Reactive Brilliant Red K-2BP and 92.5% for Reactive Brilliant Blue KN-R in 48 h. Comparing the adsorption efficiency by plain gel beads, Na-CMC plain gel beads ranked next to CTS ones. SA and PVA-SA plain gel beads hardly had the ability of adsorbing dyes. Subsequently, the growth of mycelia in Na-CMC and SA immobilized beads were evaluated. The biomass increased continuously in 72 h. The adsorption capacity of Reactive Brilliant Red K-2BP and Reactive Brilliant Blue KN-R by Na-CMC immobilized beads was 78.0 and 86.7 mg/g, respectively. The SEM micrographs show that the surface structure of Na-CMC immobilized bead is loose and finely porous, which facilitates diffusion of the dyes.