Absence of a positive bias in social anxiety: the application of a directed forgetting paradigm.

The present study used a directed forgetting paradigm to investigate whether socially anxious individuals show a memory bias for social information. Socially anxious and non-anxious participants viewed three types of words: socially negative, socially positive, and neutral. Each word was presented on a computer screen and was followed by a cue instructing participants to either remember or forget the word. A free recall test and a recognition test were then administered by asking participants to recall and recognize both "to-be-remembered" and "to-be-forgotten" words. When compared to non-anxious participants, socially anxious participants showed a greater directed forgetting effect for socially positive words in the free recall test, indicating that socially anxious individuals more easily forget socially positive words than do non-anxious individuals. This result suggests that socially anxious individuals lack the positive bias (i.e., difficulty in forgetting socially positive information) displayed by non-anxious individuals.

Synthesis and characterizations of new glycidyl-based cationic poly(aminoester) and study on gene delivery.

New glycidyl-based (epoxide-based) poly(aminoester) (EPAE) containing hydroxyl and amino groups in the backbone and side chain was synthesized. EPAE self-assembled readily with the plasmid DNA(pCMV-betagal) in HEPES buffer and was characterized by dynamic light scattering, Zeta-potential, fluorescence images, and XTT cell viability assays. To evaluate the effect of molecular weight of EPAE system on transfection, EPAE polymers with three different molecular weights (EPAE22k, EPAE18k, and EPAE8k) were also prepared. This study found that all EPAE polymers were able to bind plasmid DNA and yielded positively charged complexes with a nano-sized particles (200 nm). The EPAE22k/DNA and EPAE18k/DNA complexes were able to transfect COS-7 cell in vitro with higher transfection efficiency than other EPAE8k/DNA. These results demonstrated that molecular weight of EPAE system had a significant effect on transferring ability. Examination of the cytotoxicity of PEI25k and EPAEs system revealed that EPAEs system had lower cytotoxicity. In this article, EPAEs seemed to be a novel cationic poly(aminoester) for gene delivery and an interesting candidate for further study.

The characteristics and transfection efficiency of PEI modified by biodegradable poly(beta-amino ester).

To improve the cytotoxicity of PEI25k and the transfection efficiency of poly(beta-amino ester) with DNA, we synthesized a poly(beta-amino ester), PEDP, bearing ester linkages in the backbone and tertiary amines in the backbone and side chain and prepared a binary mixture, PEDP-PEI25k, using physical blending meyhod. Both poly(beta-amino ester) PEDP and binary mixture PEDP-PEI25k, readily self-assembled with plasmid DNA (pCMV-beta gal) in a HEPES buffer, were characterized by dynamic light scattering. The results reveal that PEDP-PEI25k was able to self-assemble plasmid DNA into PEDP-PEI25k/DNA nano-complexes small enough to enter a cell through endocytosis. Titration studies were performed to determine the buffering capacities of PEDP and PEDP-PEI25k. The COS-7 cell viabilities in the presence of PEDP and PEDP-PEI25k were studied. At low mass ratio of PEDP/PEI25k (1/1), it is found that the transfection curve of PEDP-PEI25k/DNA bearing a maximum peak is similar to that of PEI25k/DNA. In addition, the PEDP-PEI25k/DNA complexes were able to transfect COS-7 cells in vitro with a high efficiency comparable to a well-known gene carrier PEI25k/DNA. The results indicate that binary mixture PEDP-PEI25k is an attractive cationic carrier for gene delivery and an interesting candidate for further study.

Partitioning variation of heavy metals in contaminated river sediment via bioleaching: effect of sulfur added to total solids ratio.

The aim of this study was to determine the effect of the ratio of sulfur added to total sediment solids (SA/TS) on the remobilization of heavy metals from contaminated river sediment by indigenous sulfur-oxidizing bacteria. Also, the difference in metal binding fractions before and after bioleaching was explored. It was found that sediment pH decreased at a significantly faster rate at higher SA/TS ratios (0.413 and 0.199) than at lower ones. Sulfate concentrations increased at a faster rate at these higher SA/TS ratios. At the lower SA/TS ratios, more acid must be produced and therefore it took more time for sulfur-oxidizing bacteria to lower the sediment pH. Remobilization efficiency of total extractable Pb and Cr was significantly higher at higher SA/TS ratios. After bioleaching, Mn-oxides became a stronger binding pool, and the percentage of Pb and Zn bound to Mn-oxides and Cr and Cu bound to organic matter increased with the decrease of SA/TS. Different heavy metals showed different binding behavior at the various SA/TS ratios.

Induction of apoptosis by hydroxydibenzoylmethane through coordinative modulation of cyclin D3, Bcl-X(L), and Bax, release of cytochrome c, and sequential activation of caspases in human colorectal carcinoma cells.

DBM (dibenzoylmethane) is a minor constituent of licorice that has antimutagenic activity. However, its other biological activities are not well-known. The structurally related beta-diketones hydroxydibenzoylmethane (HDB) and hydroxymethyldibenzoylmethane (HMDB) were able to induce apoptosis in colorectal carcinoma COLO 205 cells. Thus, the effect of structurally related beta-diketones on cell viability, DNA fragmentation, and caspase activity was assessed. The potency of these compounds on these features of apoptosis were in the order of HDB > HMDB > DBM in colorectal carcinoma COLO 205 cells. Here, we found that HDB-induced apoptotic cell death was accompanied by upregulation of cyclin D3, Bax, and p21 and down-regulation of Bcl-X(L), while HDB had no effect on the levels of Bcl-2 and Bad protein. These results indicate that HDB allows caspase-activated deoxyribonuclease to enter the nucleus and degrade chromosomal DNA and induces DFF-45 degradation. It is suggested that HDB-induced apoptosis is triggered by the release of cytochrome c into cytosol, procaspase-9 processing, activation of caspase-3 and caspase-2, degradation of PARP, and DNA fragmentation caused by the caspase-activated deoxyribonuclease through the digestion of DFF-45. The induction of apoptosis by HDB may provide a pivotal mechanism for its cancer chemopreventive action.