Antibacterial activity of phytochemicals isolated from Atractylodes japonica against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important problems in communities and hospitals. Therefore, new agents are needed to treat acute oral infections from MRSA. In this study, antibacterial compounds from the roots of Atractylodes japonica (A. japonica) were isolated and characterized. The compounds were isolated from the root extracts using HPLC-piloted activity-guided fractionations. Four A. japonica compounds were isolated and identified as atractylenolide III (1), atractylenolide I (2), diacetylatractylodiol [(6E,12E)-tetradeca-6,12-diene-8,10-diyne-1,3-diol diacetate, TDEYA, 3). and (6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (TDEA, 4), which was obtained by hydrolysis of TDEYA. The minimum inhibitory concentrations (MICs) was determined in the setting of clinical MRSA isolates. Compound 4 showed anti-MRSA activity with a MIC value of 4-32 μg/mL. The overall results provide promising baseline information for the potential use of the extract of A. japonica as well as some of the isolated compounds in the treatment of bacterial infections.     

Synchronization criteria for coupled neural networks with interval time-varying delays and leakage delay

This paper considers the synchronization problem for coupled neural networks with interval time-varying delays and leakage delay. By construction of a suitable Lyapunov-Krasovskii’s functional and utilization of Finsler’s lemma, novel delay-dependent criteria for the synchronization of the networks are established in terms of linear matrix inequalities (LMIs) which can be easily solved by various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed methods.     

Tuning microcavities in thermally rearranged polymer membranes for CO2 capture

Microporous materials have a great importance in catalysis, delivery, storage and separation in terms of their performance and efficiency. Most microporous materials are comprised of inorganic frameworks, while thermally rearranged (TR) polymers are a microporous organic polymer which is tuned to optimize the cavity sizes and distribution for difficult separation applications. The sub-nano sized microcavities are controlled by in situ thermal treatment conditions which have been investigated by positron annihilation lifetime spectroscopy (PALS). The size and relative number of cavities increased from room temperature to 230 °C resulting in improvements in both permeabilities and selectivities for H(2)/CO(2) separation due to the significant increase of gas diffusion and decrease of CO(2) solubility. The highest performance of the well-tuned TR-polymer membrane was 206 Barrer for H(2) permeability and 6.2 of H(2)/CO(2) selectivity, exceeding the polymeric upper bound for gas separation membranes.     

In vivo NIRF Imaging of Tumor Targetability of Nanosized Liposomes in Tumor‐Bearing Mice

To optimize tumor targetability of nanosized liposomes for application as drug carriers, various liposomes are prepared by incorporating different amounts (10, 30, and 50 wt%) of cationic, anionic, and PEGylated lipids into neutral lipid. In vivo near‐infrared fluorescence images reveal that PEG‐PE/PC liposomes display high tumor accumulation in tumor‐bearing mice, while large amounts of DOTAP/PC liposomes are rapidly captured in the liver, resulting in poor tumor accumulation. These results demonstrate that optimization of the surface properties of liposomes is very important for their tumor targetability, and that in vivo imaging techniques are useful in developing and optimizing nanosized liposome‐based drug carriers.

     

New Organic Dye Based on a 3,6‐Disubstituted Carbazole Donor for Efficient Dye‐Sensitized Solar Cells

We have synthesized and characterized four organic dyes ( 9 , 10 , H1 , H2 ) based on a 3,6‐disubstituted carbazole donor as sensitizers in dye‐sensitized solar cells. These dyes have high molar extinction coefficients and energy levels suitable for electron transfer from an electrolyte to nanocrystalline TiO₂ particles. Under standard air mass 1.5 global (AM 1.5 G) solar irradiation, a device using dye H4 exhibits a short‐circuit current density (J_sc) of 13.7 mA cm^?2, an open‐circuit voltage (V_oc) of 0.68 V, a fill factor (FF) of 0.70, and a calculated efficiency of 6.52 %. This performance is comparable to that of a reference cell based on N719 (7.30 %) under the same conditions. After 1000 hours of visible‐light soaking at 60 °C, the overall efficiency remained at 95 % of the initial value.     

Syringaresinol causes vasorelaxation by elevating nitric oxide production through the phosphorylation and dimerization of endothelial nitric oxide synthase

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an important role in vascular functions, including vasorelaxation. We here investigated the pharmacological effect of the natural product syringaresinol on vascular relaxation and eNOS-mediated NO production as well as its underlying biochemical mechanism in endothelial cells. Treatment of aortic rings from wild type, but not eNOS(-/-) mice, with syringaresinol induced endothelium-dependent relaxation, which was abolished by addition of the NOS inhibitor N(G)-monomethyl-L-arginine. Treatment of human endothelial cells and mouse aortic rings with syringaresinol increased NO production, which was correlated with eNOS phosphorylation via the activation of Akt and AMP kinase (AMPK) as well as elevation of intracellular Ca(2+) levels. A phospholipase C (PLC) inhibitor blocked the increases in intracellular Ca(2+) levels, AMPK-dependent eNOS phosphorylation, and NO production, but not Akt activation, in syringaresinol- treated endothelial cells. Syringaresinol-induced AMPK activation was inhibited by co-treatment with PLC inhibitor, Ca(2+) chelator, calmodulin antagonist, and CaMKKβ siRNA. This compound also increased eNOS dimerization, which was inhibited by a PLC inhibitor and a Ca(2+)-chelator. The chemicals that inhibit eNOS phosphorylation and dimerization attenuated vasorelaxation and cGMP production. These results suggest that syringaresinol induces vasorelaxation by enhancing NO production in endothelial cells via two distinct mechanisms, phosphatidylinositol 3-kinase/Akt- and PLC/Ca(2+)/CaMKKβ-dependent eNOS phosphorylation and Ca(2+)-dependent eNOS dimerization.     

Gene mapping study for constitutive skin color in an isolated Mongolian population

To elucidate the genes responsible for constitutive human skin color, we measured the extent of skin pigmentation in the buttock, representative of lifelong non-sun-exposed skin, and conducted a gene mapping study on skin color in an isolated Mongolian population composed of 344 individuals from 59 families who lived in Dashbalbar, Mongolia. The heritability of constitutive skin color was 0.82, indicating significant genetic association on this trait. Through the linkage analysis using 1,039 short tandem repeat (STR) microsatellite markers, we identified a novel genomic region regulating constitutive skin color on 11q24.2 with an logarithm of odds (LOD) score of 3.39. In addition, we also found other candidate regions on 17q23.2, 6q25.1, and 13q33.2 (LOD ≥ 2). Family-based association tests on these regions with suggestive linkage peaks revealed ten and two significant single nucleotide polymorphisms (SNPs) on the linkage regions of chromosome 11 and 17, respectively. We were able to discover four possible candidate genes that would be implicated to regulate human skin color: ETS1, UBASH3B, ASAM, and CLTC.     

Highly selective CO2 capture on N-doped carbon produced by chemical activation of polypyrrole functionalized graphene sheets

N-doped porous carbon produced via chemical activation of polypyrrole functionalized graphene sheets shows selective adsorption of CO(2) (4.3 mmol g(-1)) over N(2) (0.27 mmol g(-1)) at 298 K. The potential for large scale production and facile regeneration makes this material useful for industrial applications.     

Compressed-exponential relaxations in supercooled liquid trehalose

We investigated the α-relaxations in supercooled liquid trehalose by using photon correlation spectroscopy (PCS) and found an interesting compressed-exponential relaxation at temperatures above 140 °C. The q^?1 dependence of its relaxation time corresponds to an ultraslow ballistic motion due to the local structure rearrangements. In the same temperature range, we found the glycosidic bond structure changes in trehalose molecule from the Raman scattering and the X-ray direction measurements. We concluded that the compressed-exponential relaxation in supercooled liquid trehalose might originate from the intra-molecular (glycosidic bond) structure change.     

Simple simulation method for investigating the performance of a SQUID gradiometer corresponding to a baseline length

Since the Superconducting Quantum Interference Device (SQUID) is the most sensitive magnetic field detector, it is widely used for measuring very weak biomagnetic signals, such as a Magnetocardiography (MCG). However, because the SQUID is easily affected by environmental magnetic noises, it is often used as a form of gradiometer suppressing spatially homogeneous field noises. The characteristic of the SQUID gradiometer mainly depends on the distance between the connected coils, that is, a baseline. Accordingly, in order to fabricate a gradiometer, the investigation of a proper baseline for the MCG signal is necessary. For the investigation, however, various gradiometers having different baselines have to be fabricated and tested, which required too much cost and effort. In this study, we suggest a simple simulation method to investigate the performance of a SQUID gradiometer depending on the baseline. In addition, in order to verify the reliability of our simulation, we fabricated wire wound axial first-order gradiometers (50 mm, 70 mm, and 100 mm baseline) and a second-order gradiometer (50 mm baseline) and compared the characteristics of the measured gradiometer signal with the simulated signal.