Effect of different mixing methods on the bacterial microleakage of calcium-enriched mixture cement.

BACKGROUND: Calcium-enriched mixture (CEM) cement is used in the field of endodontics. It is similar to mineral trioxide aggregate in its main ingredients. The present study investigated the effect of different mixing methods on the bacterial microleakage of CEM cement. METHODS: A total of 55 human single-rooted human permanent teeth were decoronated so that 14-mm-long samples were obtained and obturated with AH26 sealer and gutta-percha using lateral condensation technique. Three millimeters of the root end were cut off and randomly divided into 3 groups of 15 each (3 mixing methods of amalgamator, ultrasonic and conventional) and 2 negative and positive control groups (each containing 5 samples). BHI (brain-heart infusion agar) suspension containing Enterococcus faecalis was used for bacterial leakage assessment. Statistical analysis was carried out using descriptive statistics, Kaplan-Meier survival analysis with censored data and log rank test. Statistical significance was set at P<0.05. RESULTS: The survival means for conventional, amalgamator and ultrasonic methods were 62.13±12.44, 68.87±12.79 and 77.53±12.52 days, respectively. The log rank test showed no significant differences between the groups. CONCLUSIONS: Based on the results of the present study it can be concluded that different mixing methods had no significant effect on the bacterial microleakage of CEM cement.

The phosphorus speciations in the sediments up- and down-stream of cascade dams along the middle Lancang River.

We detected the longitudinal variability of phosphorus speciations and its relation to metals and grain size distribution of sediments in three cascade canyon reservoirs (Xiaowan, Manwan and Dachaoshan) along Lancang River, China. Five phosphorus speciations including loosely bound P (ex-P), reductant soluble P (BD-P), metal oxide-bound P (NaOH-P) calcium-bound P (HCl-P) and residual-P were extracted and quantified. Results showed that in Manwan Reservoir HCl-P accounted for the largest part of total phosphorus (TP) (49.69%), while in Xiaowan and Dachaoshan reservoirs, NaOH-P was the most abundant speciation which accounted for 57.21% and 55.19% of total phosphorus respectively. Higher contents of bio-available phosphorus in Xiaowan and Dachaoshan reservoirs suggested a high rate of P releasing from sediments. Results also showed ex-P and HCl-P had positive correlation with Ca. Total phosphorus was positively correlated with Fe. The silt/clay contents of the sediments had close relationship with ex-P (r=0.413, p<0.05), NaOH-P (r=0.428, p<0.05) and BAP (r=0.458, p<0.05). The concentration of Ca, Mn and silt/clay speciation in the sediments explained 40%, 10% and 4% of the spatial variation of phosphorus speciations, respectively.

Thermosensitive and biocompatible cyclotriphosphazene micelles.

A new class of thermosensitive micellar cyclotriphosphazenes has been synthesized by stepwise nucleophilic substitutions of hexachlorocyclotriphosphazene with a hydrophilic methoxy poly(ethylene glycol) (MPEG) and a hydrophobic oligopeptide selected from tetra- to hexapeptides, and characterized by means of multinuclear ((1)H, (31)P) NMR spectroscopy, elemental analysis, and dynamic light scattering (DLS) method. All the amphiphilic trimers were found to form stable micelles by self-assembly in aqueous solution and to exhibit a lower critical solution temperature in the range of 20-48 degrees C in water depending on the hydrophilic to hydrophobic balance of the side groups. The micelles formed from the trimers bearing MPEG350 and a tetra- or pentapeptide were found to have a mean diameter of 13-14 nm, while, surprisingly, the trimers bearing longer MPEG550 and hexapeptides have shown remarkable contraction of their micelle size to a mean diameter of 7-8 nm, probably due to the strong intermolecular hydrophobic interactions among the hexapeptide groups of the trimers. The local tolerance tests using rabbits have shown excellent biocompatibility of the trimers. Also a promising in vitro releasing profile was obtained for local delivery of human growth hormone (hGH) as a model protein drug.

Phycoremediation: key issues for cost-effective nutrient removal processes.

Phycoremediation applied to the removal of nutrients from animal wastewater and other high organic content wastewater is a field with a great potential and demand considering that surface and underground water bodies in several regions of the world are suffering of eutrophication. However, the development of more efficient nutrient removal algal systems requires further research in key areas. Algae growth rate controls directly and indirectly the nitrogen and phosphorus removal efficiency. Thus, maximum algae productivity is required for effective nutrient removal and must be considered as a key area of research. Likewise, low harvesting costs are also required for a cost-effective nutrient removal system. The use of filamentous microalgae with a high autoflocculation capacity and the use of immobilized cells have been investigated in this respect. Another key area of research is the use of algae strains with special attributes such as tolerance to extreme temperature, chemical composition with predominance of high added value products, a quick sedimentation behavior, or a capacity for growing mixotrophically. Finally, to combine most of the achievements from key areas and to design integrated recycling systems (IRS) should be an ultimate and rewarding goal.

Bioavailability and efficacy of antisense morpholino oligomers targeted to c-myc and cytochrome P-450 3A2 following oral administration in rats.

Antisense phosphorodiamidate Morpholino oligomers (PMO) are resistant to degradation by cellular hydrolases, DNases, RNases, and phosphodiesterases, but remain sensitive to prolonged exposure to low pH. The present studies evaluate the oral fractional bioavailability, stability, and efficacy of two distinct PMO sequences targeted to c-myc and cytochrome P-450 (CYP) 3A2. The c-myc antisense 20-mer, AVI-4126 (5'-ACGTTGAGGGGCATCGTCGC-3'), slowed the regenerative process in the rat liver after a 70% partial hepatectomy (PH). Rats were administered 3.0 mg/kg AVI-4126 in 0.1 mL saline via a bolus intravenous injection or in 0.5 mL sterile phosphate-buffered saline via gavage immediately following PH. The areas under the plasma concentration versus time curves revealed a fractional oral availability of 78.8% over a period of 10 min through 24 h. Immunoblot analysis of liver tissue from rats treated orally with AVI-4126 demonstrated a sequence-specific reduction in the target protein c-Myc, as well as secondary proliferation markers: proliferating cell nuclear antigen (PCNA), cyclin D1, and p53. The CYP3A2 antisense 22-mer AVI-4472 (5'-GAGCTGAAAGCAGGTCCATCCC-3') caused a sequence-dependent reduction of approximately five-fold in the rat liver CYP3A2 protein levels and erythromycin demethylation activity in 24 h following oral administration at a dose of 2 mg/kg. It is concluded that oral administration of PMOs can inhibit c-myc and CYP3A2 gene expression in rat liver by an antisense-based mechanism of action. These studies highlight the potential for development of PMOs as orally administered therapeutic agents.

[Nutrition of wheat under wet injury and its regulation].

With pot experiment, this paper dealt with the effects of different nutrition regulations on nutrient absorption and crop yield of wheat under waterlogged condition. N, P, K, Zn, Cu uptakes by wheat were greatly inhibited by waterlogging. The total amounts of reusable elements N, P, K and Zn in leaves decreased obviously in stems but did not in ears, compared with control; while the total amount of element Cu in all parts was reduced by waterlogging. The yield of individual wheat plant was significantly reduced under waterlogging. Additional N-fertilizer or spraying N, P and K significantly increased the uptake of nutrients and the yield for Wanmai 19 under light waterlogging, but were not effective for Yanmai 158 under heavy waterlogging. A positive correlation was found between the yield of wheat under waterlogging and the N accumulation in leaves.