Characteristics of a label-free piezoelectric immunosensor detecting Pseudomonas aeruginosa

A label-free immunosensor system detecting a psychrophylic bacterium, Pseudomonas aeruginosa was developed as follows. Four types of anti-P. aeruginosa antibody were individually chemisorbed onto one-side gold electrodes of piezoelectric quartz crystals according to a thiolated antibody coupling procedure initiated with a thiol-cleavable heterobifunctional cross-linker, sulfosuccinimidyl-6-[3-(2-pyridyldithio)propionamido]hexanoate. A flow-type biosensor system was operated optimally at 0.2 M sodium potassium phosphate, pH 7.2 with a minimal matrix effect and the selected flow rate for it was 0.155 ml/min. A biosensor response was detected by measuring a steady-state resonant frequency shift after the response time around 8 min. The frequency shifts obtained were quite specific according to the antibody types and P. aeruginosa strains. The biosensor responses to varying concentrations of the P. aeruginosa cells ranging from 1.3×10⁷ to 1.3×10⁸ CFU/ml were determined as 17–176 Hz and a linear calibration curve (r=0.942) was obtained by plotting the responses in a double-logarithmic scale. The selectivity of the biosensor between P. aeruginosa and Xanthomonas spp. which both belong to the aerobic pseudomonads was, however, not so good owing to the property of the antibody used. The sensor chip could be reused at least seven times without an appreciable decrease in sensitivity.     

Low latency and energy efficient routing tree for wireless sensor networks with multiple mobile sinks

We propose the minimum Wiener index spanning tree (MWST) as a routing topology that is suitable for sensor networks with multiple mobile base nodes. However, it was proved that finding a spanning tree with the minimum Wiener index from a weighted graph is NP-hard. To address this problem and analyze the effectiveness of the MWST as the routing tree on sensor networks with multiple mobile base nodes, we designed two algorithms: a branch and bound algorithm for small-scale wireless sensor networks and a simulated annealing algorithm for large-scale wireless sensor networks. The simulation results show that MWST outperforms the minimum spanning tree (MST), one of the representative spanning trees used in many routing protocols for sensor networks, in terms of energy efficiency and packet delay.     

Plant Alkaloid Tetrandrine Is a Nuclear Receptor 4A1 Antagonist and Inhibits Panc-1 Cell Growth In Vitro and In Vivo

The orphan nuclear receptor 4A1 (NR4A1) is highly expressed in human pancreatic cancer cells and exerts pro-oncogenic activity. In a previous study, we demonstrated that fangchinoline (FCN), a natural inhibitor of nuclear NR4A1, induces NR4A1-dependent apoptosis in human pancreatic cancer cells. In this study, we evaluated FCN and its structural analogs (berbamine, isotetrandrine, tetrandrine, and tubocurarine) for their inhibitory effects on NR4A1 transactivity, and confirmed that tetrandrine (TTD) showed the highest inhibitory effect in pancreatic cancer cells. Moreover, in a tryptophan fluorescence quenching assay, TTD directly bound to the ligand binding domain (LBD) of NR4A1 with a K_D value of 10.60 μM. Treatment with TTD decreased proliferation and induced apoptosis in Panc-1 human pancreatic cancer cells in part through the reduced expression of the Sp1-dependent anti-apoptotic gene survivin and induction of ROS-mediated endoplasmic reticulum stress, which are the well-known NR4A1-dependent proapoptotic pathways. Furthermore, at a dose of 25 mg/kg/day, TTD reduced tumor growth in an athymic nude mouse xenograft model bearing Panc-1 cells. These data show that TTD is an NR4A1 antagonist and that modulation of the NR4A1-mediated pro-survival pathways is involved in the antitumor effects of TTD.     

Inhibitory effect of fractions from skullcap (<Emphasis Type="Italic">Scutellaria baicalensis</Emphasis> Georgi) on osteoclast differentiation and bone resorption

This study was performed to evaluate the effects of skullcap (Scutellaria baicalensis Georgi, SBG) on differentiation of RAW 264.7 cell into osteoclast-like cells and bone resorption of mature osteoclast to propose candidates for the prevention or treatment of osteoporosis. In the screening of 140 natural products, the selected SBG methanol extract dramatically reduced tartrate-resistant acid phosphatase (TRAP) activity to 21% at 10 μg/mL. The proliferation was evaluated using the MTT assay, and the survival rates of RAW 264.7 cells treated with 10–100 μg/mL extract were over 80% with most concentrations. The chloroform fraction from SBG (SBG-C) decreased TRAP activity. The SBG-C increased the expression of the pro-apoptotic protein Bax and reduced the expression of the anti-apoptotic protein Bcl-2. It also stimulated caspase-3 activity in osteoclasts. In addition, the actin rings were loose and fuzzy in the presence of these fractions. A resorption pit was formed by multinucleated osteoclastic cells, but was not observed in the presence of the SBG-C (10 μg/mL). In conclusion, we found SBG suppressed osteoclast differentiation and bone resorption. It also inhibited osteoclast survival. Therefore SBG is expected to be a natural source for the development of functional food and medical agents to prevent or treat osteoporosis.     

Characterization of dextran produced from Leuconostoc citreum S5 strain isolated from Korean fermented vegetable

The production of dextran was optimized by a novel Leuconostoc citreum, which was isolated from Korean traditional fermented vegetable, Dongchimi. This strain was identified as Leuconostoc citreum S5 by a physiological analysis, API-kit analysis, 16-rDNA sequencing and RAPD-PCR. The type and production of dextrans were greatly affected by the sucrose concentration, food ingredients and fermentation time. In particular, the addition of skim milk and potato powder greatly increased the consistency of the culture broth after fermentation for 12 h at 30 °C, resulting in the maximum values after 72 h. The culture broth with the highest consistency, was obtained from the defined medium containing 20% sucrose, 1.5% skim milk and 0.5% potato powder, and it showed typical pseudoplastic behavior with a pH of 4.07, 1.12% titratable acidity, 472.5 Pa of the elasticity modulus (G′) and 85.0 Pa of viscosity modulus (G″). In addition, total dextran is composed of soluble dextran (33.2 g/L) and insoluble dextran (29.8 g/L). The conversion yield of sucrose was decreased by an increase, in the sucrose concentration in a defined medium, remaining sucrose and some of glucose and fructose. High-molecular weight dextran (2,000 kDa), as a minor fraction, was produced by increasing the sucrose. With the addition of food ingredients such as skim milk and potato powder, however, the conversion of sucrose is complete, showing only some fructose as a by-product. Low-molecular weight dextran (1,100 kDa) was only produced regardless of sucrose concentration.     

Suppression of LPS-induced inflammatory activities by Rosmarinus officinalis L.

Rosemary (Rosmarinus officinalis L.) has been used in folk medicine to treat headaches, epilepsy, poor circulation, and many other ailments. It was found that rosemary could act as a stimulant and mild analgesic and could reduce inflammation. However, the mechanisms underlying the anti-inflammatory effects of rosemary need more study to be established. Therefore, in this study, the effects of rosemary on the activation of nuclear factor kappa beta (NF-kB) and mitogen-activated protein kinases (MAPKs), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), and cytokine in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were investigated. A methanol extract of rosemary and its hexane fraction reduced NO generation with an IC₅₀ of 2.75 and 2.83 μg/ml, respectively. Also, the methanol extract and the hexane fraction inhibited LPS-induced MAPKs and NF-kB activation associated with the inhibition of iNOS or COX-2 expression. LPS-induced production of PGE₂ and tumour necrosis factor-alpha (TNF-α) were blocked by rosemary. Rosemary extract and its hexane fraction are important for the prevention of phosphorylation of MAPKs, thereby blocking NF-kB activation, which in turn leads to decreased expression of iNOS and COX-2, thus preventing inflammation.     

Fluorescence polarization immunoassay based on a monoclonal antibody for the detection of ochratoxin A

A fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody for the determination of ochratoxin A (OTA) was developed. Fluorescein‐labelled OTA derivative (tracer) was synthesized and purified by thin‐layer chromatography. The optimized OTA FPIA had a dynamic range from 5 to 200 ng mL^?1 with IC₅₀ value of 30 ng mL^?1 and a detection limit of 3 ng mL^?1. The method developed was characterized by high specificity and reproducibility. Cross‐reactivity with other mycotoxins (zearalenone, aflatoxins, patulin and T‐2 toxin) was negligible (<0.1%). Methanol extracts of barley samples were used for the analysis. The results of OTA determination in barley were compared with those determined by indirect competitive enzyme‐linked immunosorbent assay (ELISA). Recoveries for the samples spiked at 50, 100 and 500 ng g^?1 levels were 91, 90 and 97%, respectively, for FPIA, and 98, 98 and 102%, for ELISA. Naturally contaminated barley samples were analysed by these methods but some disagreement was observed between the results. The FPIA method can be applied for screening of food samples for OTA residues without a complicated clean‐up.     

Application of novel HPLC method to the analysis of regional and seasonal variation of the active compounds in Paeonia lactiflora

Alcohol extracts of the dried root of paeony (Paeonia lactiflora), an Oriental medicinal herb, have been reported to contain cardiovascular protective monoterpene glycosides such as paeoniflorin and albiflorin. To analyze these compounds, a novel HPLC method with good precision was developed by a gradient elution making use of Inertsil ODS-3 column and acetonitrile–H₂O as the eluent. At the optimum analytical condition, albiflorin and paeoniflorin were resolved well with the retention times of 14.30 and 17.74 min, respectively. By applying this method, the contents of paeoniflorin and albiflorin in 12 regional samples of paeony root were compared. The contents of these compounds in the seasonal samples from different parts of 4 year-grown paeony were also analyzed, with the highest values in the root sample of June, which was expected to be applicable to a cultivation management for producing paeony root with good functional activity.     

Anti-allergy effect of marc from silver vine Actinidia polygama prepared by supercritical fluid extraction

Anti-allergic effect of marc extract after supercritical fluid extraction SFE comparing the crude extract from silver vine was investigated to increase its potential for use as a new source of functional food that reduced non-favorable flavor. The results tested by thiazolyl blue tetrazolium bromide MTT assay indicated that the ethanol extract of silver vine ETOH and ethanol extract of SFE marc SFEM showed no cytotoxic effects on IgE-sensitized rat basophilic leukemia RBL-2H3 cells under the conditions. ETOH, as well as SFEM inhibited antigen-induced degranulation in RBL-2H3 mast cells dose dependently. The morphological change of the cells treated with compound 48/80 was prevented by the extracts. Production of tumor necrosis factor TNF-α on the activated RBL-2H3 cells was also reduced by ETOH and SFEM, similarly. Moreover, the total phenolic content of the extracts seems to correlate with the anti-allergic activity. In conclusion, the results suggest that the flavor-improved SFE marc extract suppressed the antigen-induced allergic reactions in RBL-2H3 mast cells.