Contamination evaluation and source identification of heavy metals in sediments near outlet of Shekou industrial district of Shenzhen City.

Sediment samples in this study were taken from five typical sites near the outlet of Shekou industrial district of Shenzhen City, China. The concentrations of seven elements including Cr, Cu, Cd, Pb, Hg, Zn, and As were determined respectively by atomic absorption spectrometry or atomic fluorescence spectrometry. The pollution degrees of the seven elements were assessed with the contamination factor and potential ecological risk index respectively, and their different sources were identified using multivariate statistical methods. The calculated contamination factors of these elements indicated that the sediments were at least moderately polluted by all the surveyed elements except As. The values of potential ecological risk indexes obtained decreased as the following order: Cd > Hg > Cu > As > Pb > Zn > Cr, and suggested that Cd and Hg were respectively at high and considerable environmental health risks. In addition, multivariate statistical analyses indicated that Cd, Hg, Cu, and Zn were most likely from the waste of electroplating, metal, and battery industries at Shekou industrial district, while Pb and As originated from both natural processes and anthropogenic activities along the bank of Pear River such as coal transportation and combustion, glass manufacturing, and painting, and Cr came mostly from Cr-related industries especially leather tanning within Shenzhen City. This study provided useful reference information about heavy metal contamination in the sediments in the estuarine and coastal areas with rapid urbanization and industrialization, and should be very helpful for the local governments to make relevant policies and strategies of heavy metal contamination control and management in developing countries.

Multi-spectroscopic studies on the interaction between traditional Chinese herb, helicid with pepsin.

Study on the binding properties of helicid by pepsin systematically using multi-spectroscopic techniques and molecular docking method, and these interactions comprise biological recognition at molecular level and backbone of biological significance in medicine concerned with the uses, effects, and modes of action of drugs. We investigated the mechanism of interaction between helicid and pepsin by using various spectroscopic techniques viz., fluorescence spectra, UV-Vis absorption spectra, circular dichroism (CD), 3D spectra, synchronous fluorescence spectra and molecular docking methods. The quenching mechanism associated with the helicid-pepsin interaction was determined by performing fluorescence measurements at different temperatures. From the experimental results show that helicid quenched the fluorescence intensity of pepsin via a combination of static and dynamic quenching process. The binding constants (Ka) at three temperatures (288, 298, and 308 K) were 7.940 × 107, 2.082 × 105 and 3.199 × 105 L mol-1, respectively, and the number of binding sites (n) were 1.44, 1.14, and 1.18, respectively. The n value is close to unity, which means that there is only one independent class of binding site on pepsin for helicid. Thermodynamic parameters at 298 K were calculated as follows: ΔHo (- 83.85 kJ mol-1), ΔGo (- 33.279 kJ mol-1), and ΔSo (- 169.72 J K-1 mol-1). Based on thermodynamic analysis, the interaction of helicid with pepsin is driven by enthalpy, and Van der Waals' forces and hydrogen bonds are the main forces between helicid and pepsin. A molecular docking study further confirmed the binding mode obtained by the experimental studies. The conformational changes in the structure of pepsin was confirmed by 3D fluorescence spectra and circular dichroism.

Latent growth curves and predictors of depressive symptoms among Chinese adolescent earthquake survivors.

The objective of this longitudinal study was to identify growth curves and related predictors of depressive symptoms among Chinese adolescent earthquake survivors. A total of 1573 adolescent survivors of the 8-magnitude Wenchuan earthquake were assessed through the Depression Self-Rating Scale for Children (cutoff for probable clinical depression: 15), Social Support Rate Scale, Adolescent Self-Rating Life Events Checklist, and a self-designed questionnaire covering earthquake exposure and demographic information at 6-, 12-, 18-, 24- and 30-months after the earthquake. Data were analyzed using growth mixture modeling (GMM) and multinomial logistic regression. The prevalence rates of depressive symptoms were 27.6%, 40.6%, 30.9%, 37.5% and 29.8% at 6-, 12-, 18-, 24- and 30-months, respectively. GMM analysis showed four patterns of growth curves for depressive symptoms: chronic depression (25.6% of the sample), recovery (1.7%), delayed depression (4.3%), and resilience (68.4%). Female gender was related with decreased probability of resilience. Direct witness of tragic scenes during the earthquake was related with higher risk for chronic depression. More negative life events and fewer social support were also common predictors of not developing the resilience pattern. The need of providing appropriate individualized interventions for high-risk adolescent earthquake survivors is indicated.

Trajectory and predictors of depressive symptoms among adolescent survivors following the Wenchuan earthquake in China: a cohort study.

OBJECTIVE: To investigate the trajectory of depressive symptoms among adolescents exposed to the Wenchuan earthquake as well as predictors after the earthquake. METHODS: A cohort of students (N = 1,573) in the 7th and 10th grades from Dujiangyan city was followed-up periodically for 2 years. Participants were assessed at 6, 12, 18, and 24 months after the earthquake. Adolescents completed the Depression Self-rating Scale for Children, Adolescent Self-Rating Life Event Checklist, Resilience Scale, and earthquake exposure questionnaire. RESULTS: The prevalence rates of depressive symptoms at 6, 12, 18 and 24 months were 27.4, 41, 31.9, and 38.3 %, respectively. The number of adolescents who kept no depressive symptoms and persistent depressive symptoms at each stage was stable, accounted for almost 50 and 20 % of the total, respectively. Adolescents turning no depressive symptoms to depressive symptoms were mostly in 6-12 months, followed by 18-24 months. Additionally, girls (OR 1.24-1.37), post-disaster negative life events (OR for high vs. low = 5.54-15.06), resilience (OR for low vs. high = 9.40-13.69), and depressive symptoms at previous stage (OR 4.96-6.03) had a long-term effect on depressive symptoms, while the impact of earthquake exposure diminished with the passage of time and could not predict depressive symptoms after one and a half years after the earthquake. CONCLUSIONS: Among adolescent survivors, the resistance and persistence of depressive symptoms were common. Moreover, depressive symptoms tended to outbreak close to the anniversary date, showing the anniversary reaction. Adolescent girls, adolescents who encountered high levels of life events, had low levels of resilience and a history of depressive symptoms should be provided with psychological intervention.

Enhanced Performance of Bioelectrodes Made with Amination-Modified Glucose Oxidase Immobilized on Carboxyl-Functionalized Ordered Mesoporous Carbon.

This research reveals the improved performance of bioelectrodes made with amination-modified glucose oxidase (GOx-NH2) and carboxyl-functionalized mesoporous carbon (OMC-COOH). Results showed that when applied with 10 mM EDC amination, the functional groups of NH2 were successfully added to GOx, according to the analysis of 1H-NMR, elemental composition, and FTIR spectra. Moreover, after the aminated modification, increased enzyme immobilization (124.01 ± 1.49 mg GOx-NH2/g OMC-COOH; 2.77-fold increase) and enzyme activity (1.17-fold increase) were achieved, compared with those of non-modified GOx. Electrochemical analysis showed that aminated modification enhanced the peak current intensity of Nafion/GOx-NH2/OMC-COOH (1.32-fold increase), with increases in the charge transfer coefficient α (0.54), the apparent electron transfer rate constant ks (2.54 s-1), and the surface coverage Γ (2.91 × 10-9 mol·cm-2). Results showed that GOx-NH2/OMC-COOH exhibited impressive electro-activity and a favorable anodic reaction.

Macrophage-stimulating activity of European eel (Anguilla anguilla) peptides in RAW264.7 cells mediated via NF-κB and MAPK signaling pathways.

European eel (Anguilla anguilla) is considered to be a vital commercial fish species. In this study, the effect and molecular mechanism of bioactive peptides from European eel on macrophage-stimulating activity in RAW264.7 cells were investigated. Eel peptide (EP) markedly induced NO and iNOS production and promoted TNF-α and IL-6 secretion in a concentration-dependent manner. Moreover, EP dose-dependently activated NF-κB and MAPK signaling pathways in RAW264.7 cells. In addition, EP was purified using a Sephadex A-25 column and a Bio-Gel P-6 column, and the fraction (Fr-1-1) showing the strongest NO-inducing activity was obtained. Then, the molecular weights of the components in Fr-1-1 were analyzed by LC-MS/MS and found to range from 700 to 1900 Da for the majority of components, which suggested that Fr-1-1 mainly consisted of peptides containing 8-20 amino acid residues. Overall, our results indicated that EP from Anguilla anguilla activated macrophages and could be used as a potential nutraceutical or pharmaceutical.

Trypsin inhibition by Ligupurpuroside B as studied using spectroscopic, CD, and molecular docking techniques.

It is well known that Ligupurpuroside B is a water-soluble polyphenolic compound and used to brew bitter tea with antioxidant activities. It acted as a stimulant to the central nervous system and a diuretic (increase the excretion of urine), was used to treat painful throat and high blood pressure, and also exerted weight-loss function. In this regard, a detailed investigation on the mechanism of interaction between Ligupurpuroside B and trypsin could be of great interest to know the pharmacokinetic behavior of Ligupurpuroside B and for the design of new analogues with effective pharmacological properties. Ligupurpuroside B successfully quenched the intrinsic fluorescence of trypsin via static quenching mechanism. The binding constants (Ka) at three temperatures (288, 298, and 308 K) were 1.7841 × 104, 1.6251 × 104 and 1.5483 × 104 L mol-1, respectively. Binding constants revealed the stronger binding interaction between Ligupurpuroside B and trypsin. The number of binding sites approximated to one, indicating a single class of binding for Ligupurpuroside B in trypsin. The enzyme activity result suggested that Ligupurpuroside B can inhibit trypsin activity. Thermodynamic results revealed that both hydrogen bonds and hydrophobic interactions play main roles in stabilization of Ligupurpuroside B-trypsin complex. Circular dichroism (CD) results showed that the conformation of trypsin changed after bound to ligupurpuroside B. Molecular docking indicated that Ligupurpuroside B can enter the hydrophobic cavity of trypsin and was located near Trp215 and Tyr228 of trypsin. Communicated by Ramaswamy H. Sarma.

Immune Activation of RAW264.7 Macrophages by Low Molecular Weight Fucoidan Extracted from New Zealand Undaria pinnatifida.

Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, has been shown to possess various bioactivities. In particular, low molecular weight fucoidan (LMWF) has been shown to have better bioactivities. In this study, a LMWF (<10 kDa) was extracted from New Zealand Undaria pinnatifida and investigated for its immune modulation effects. LMWF at a concentration range from 1 to 50 µg/mL exerted an effective immune activation in RAW264.7 macrophages. LMWF treatment promoted significant NO release, iNOS expression, and TNF-α and IL-6 secretion in a concentration-dependent manner. It also significantly stimulated the activation of NF-κB and MAPK signaling pathways, and specific inhibitors of NF-κB and MAPK pathways diminished the stimulation, confirming the activation pathways. These results indicate that LMWF possesses potential health benefits through immune-stimulation, which may lead to future pharmaceutical development.

Assessment of pollutions and identification of sources of heavy metals in sediments from west coast of Shenzhen, China.

The sediment samples were collected from eight sites located in the Pearl River Estuary and the Shenzhen Bay of the west coast of Shenzhen. The distributions of the seven elements Zn, Cr, Hg, Cu, Cd, Pb and As have been analyzed, and their pollution degrees, corresponding potential ecological risks and source identifications have been studied using geo-accumulation index, potential ecological risk index and integrated multivariate statistical methods, respectively. Based on the calculated geo-accumulation indices, the contamination levels of all elements in the Pearl River Estuary are similar to those in the Shenzhen Bay, reflecting that these elements in the study areas have similar sources because of the adequate seawater exchange. The calculated potential ecological risk indices suggest that Cd and Hg are at considerable and moderate risk, respectively. Multivariate statistical analyses further reveal that Zn, Hg, Cd and Pb originated from industrial wastewater, while Cr and Cu are mainly from both industrial wastewater and agricultural sources, and As is mainly from natural source. These research results provide baseline information for both the coastal environment management and the worldwide heavy metal distribution and assessment.

Comparative studies on DNA-binding and in vitro antitumor activity of enantiomeric ruthenium(II) complexes.

A pair of ruthenium(II) complex enantiomers, Δ- and Λ-[Ru(bpy)2PBIP]2+ {bpy=2,2'-bipyridine, PBIP=2-(4-bromophenyl)imidazo[4,5-f]1,10-phenanthroline} have been synthesized and characterized. The systematic comparative studies between two enantiomers on their DNA binding-behaviors with calf thymus DNA (CT DNA) were carried out by viscosity measurements, spectrophotometric methods and molecular simulation technology. Additional assays were performed to explore the cytotoxicity of the ruthenium(II) enantiomers against tumor cell lines. DNA-binding studies show that both the enantiomers can bind to CT DNA via intercalative mode, and the Δ form binds to CT DNA more strongly than the Λ form does. Molecular simulation further shows that both the two enantiomers intercalate between base pairs of DNA in minor groove, and that the Δ form intercalates into DNA more deeply than the Λ form does. In addition, the cell proliferation assays show that the Δ form induces a greater cytotoxicity than the Λ form on human cervical cancer HeLa cells, which is positive correlated with the results in DNA binding studies and molecular docking, and implies that the DNA binding affinities of ruthenium(II) polypyridyl complexes might be constitute to the part of their anticancer mechanisms.

Binding mechanism of lipase to Ligupurpuroside B extracted from Ku-Ding tea as studied by multi-spectroscopic and molecular docking methods.

The interaction of lipase with Ligupurpuroside B was studied by multiple spectroscopic techniques, enzyme activity and molecular modeling under simulative physiological condition. According to Stern-Volmer equation, fluorescence of lipase was quenched by Ligupurpuroside B via a static quenching mechanism because of formation of Ligupurpuroside B-lipase complex. Binding constants, number of binding sites & thermodynamic parameters were evaluated. The values of ΔGo (-25.085 kJ mol-1), ΔHo (-12.14 kJ mol-1) and ΔSo (+43.45 J mol-1 K-1) at 298 K indicated that Ligupurpuroside B-lipase interaction is spontaneous and hydrophobic interaction is the main force stabilizing the Ligupurpuroside B-lipase complex. The enzyme activity assay showed that Ligupurpuroside B inhibited lipase activity efficiently. Synchronous fluorescence spectra (SFS) suggested that Ligupurpuroside B is closer to Trp residues than to Tyr residues. All above experimental results were confirmed by molecular docking studies, which further indicated the binding site of Ligupurpuroside B on the surface of lipase, and the amino acid residues of lipase interacting with Ligupurpuroside B. Our present research work gives valuable information on the design of drugs with lipase as a carrier and should be useful for food industries.

Elucidation of the Molecular-Mechanisms and In Vivo Evaluation of the Anti-inflammatory Effect of Alginate-Derived Seleno-polymannuronate.

Alginate-derived polymannuronate (PM) is a type of polysaccharide found in edible brown seaweeds. Seleno-polymannuronate (Se-PM) was prepared from PM via synthesis using sulfation- and selenation-replacement reactions. The anti-inflammatory activity of Se-PM and its corresponding molecular mechanisms were investigated. In lipopolysaccharide (LPS)-activated murine macrophage RAW264.7 cells, Se-PM significantly attenuated the production of nitric oxide (NO), prostaglandin E2 (PGE2), and reactive oxygen species (ROS); the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2); and the secretion of proinflammatory cytokines. Moreover, Se-PM remarkably suppressed the LPS-induced activation of the nuclear-factor (NF)-κB and mitogen-activated-protein-kinase (MAPK) signaling pathways in RAW264.7 cells. Furthermore, Se-PM also decreased the production of proinflammatory mediators in LPS-triggered primary murine macrophages. Additionally, Se-PM inhibited the inflammatory response in the air-pouch inflammation model. These results might contribute to the overall understanding of the potential health benefits of Se-PM for food and drug applications.

Alginate enhances Toll-like receptor 4-mediated phagocytosis by murine RAW264.7 macrophages.

Alginate is a naturally acidic polysaccharide consisting alternately of ß-d-mannuronic acid and α-l-guluronic acid with 1, 4-glycosidic linkages and is derived from brown seaweeds. Herein, the effect of alginate on the promotion of macrophage phagocytosis and the corresponding molecular mechanisms were investigated in murine RAW264.7 cells. Alginate could enhance the intracellular phagocytosis of gold nanoparticles (AuNPs), fluorescent microspheres and immunoglobulin G (IgG)-opsonized Staphylococcus aureus (S. aureus). Moreover, alginate increased Toll-like receptor 4 (TLR4) expression and activated the Akt/nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signalling pathways. Alginate-promoted phagocytosis was suppressed by the addition of inhibitors of TLR4, NF-κB and p38 MAPK and by TLR4 gene knockdown, indicating the involvement of these key components. This work is the first to propose that alginate promotes phagocytosis via upregulating TLR4 expression and stimulating the Akt/NF-κB and p38 MAPK signalling pathways, which may contribute to the capacity of alginate to activate macrophages.