G-quadruplex structural variations in human genome associated with single-nucleotide variations and their impact on gene activity.

G-quadruplexes (G4s) formed by guanine-rich nucleic acids play a role in essential biological processes such as transcription and replication. Besides the >1.5 million putative G-4-forming sequences (PQSs), the human genome features >640 million single-nucleotide variations (SNVs), the most common type of genetic variation among people or populations. An SNV may alter a G4 structure when it falls within a PQS motif. To date, genome-wide PQS-SNV interactions and their impact have not been investigated. Herein, we present a study on the PQS-SNV interactions and the impact they can bring to G4 structures and, subsequently, gene expressions. Based on build 154 of the Single Nucleotide Polymorphism Database (dbSNP), we identified 5 million gains/losses or structural conversions of G4s that can be caused by the SNVs. Of these G4 variations (G4Vs), 3.4 million are within genes, resulting in an average load of >120 G4Vs per gene, preferentially enriched near the transcription start site. Moreover, >80% of the G4Vs overlap with transcription factor-binding sites and >14% with enhancers, giving an average load of 3 and 7.5 for the two regulatory elements, respectively. Our experiments show that such G4Vs can significantly influence the expression of their host genes. These results reveal genome-wide G4Vs and their impact on gene activity, emphasizing an understanding of genetic variation, from a structural perspective, of their physiological function and pathological implications. The G4Vs may also provide a unique category of drug targets for individualized therapeutics, health risk assessment, and drug development.

Telomere- and telomerase-interacting protein that unfolds telomere G-quadruplex and promotes telomere extension in mammalian cells.

Telomere extension by telomerase is essential for chromosome stability and cell vitality. Here, we report the identification of a splice variant of mammalian heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2), hnRNP A2*, which binds telomeric DNA and telomerase in vitro. hnRNP A2* colocalizes with telomerase in Cajal bodies and at telomeres. In vitro assays show that hnRNP A2* actively unfolds telomeric G-quadruplex DNA, exposes 5 nt of the 3' telomere tail and substantially enhances the catalytic activity and processivity of telomerase. The expression level of hnRNP A2* in tissues positively correlates with telomerase activity, and overexpression of hnRNP A2* leads to telomere elongation in vivo. Thus, hnRNP A2* plays a positive role in unfolding telomere G-quadruplexes and in enhancing telomere extension by telomerase.

Effects of decabrominated diphenyl ether (PBDE 209) on voltage-gated sodium channels in primary cultured rat hippocampal neurons.

Polybrominated diphenyl ethers (PBDEs) are widely used as flame-retardant additives. But the application of PBDEs has been challenged due to their toxicity, especially neurotoxicity. In this study, we investigated the effects of decabrominated diphenyl ether (PBDE 209), the major PBDEs product, on voltage-gated sodium channels (VGSCs) in primary cultured rat hippocampal neurons. Employing the whole-cell patch-clamp technique, we found that PBDE 209 could irreversibly decrease voltage-gated sodium channel currents (I(Na)) in a very low dose and in a concentration-dependent manner. We had systematically explored the effects of PBDE 209 on I(Na) and found that PBDE 209 could shift the activation and inactivation of I(Na) toward hyperpolarizing direction, slow down the recovery from inactivation of I(Na), and decrease the fraction of activated sodium channels. These results suggested that PBDE 209 could affect VGSCs, which may lead to changes in electrical activities and contribute to neurotoxicological damages. We also showed that ascorbic acid, as an antioxidant, was able to mitigate the inhibitory effects of PBDE 209 on VGSCs, which suggested that PBDE 209 might inhibit I(Na) through peroxidation. Our findings provide new insights into the mechanism for the neurological symptoms caused by PBDE 209.

Case-control study of blood lead levels and attention deficit hyperactivity disorder in Chinese children.

BACKGROUND: Attention deficit/hyperactivity disorder (ADHD) and lead exposure are high-prevalence conditions among children. OBJECTIVE: Our goal was to investigate the association between ADHD and blood lead levels (BLLs) in Chinese children, adjusting for known ADHD risk factors and potential confounding variables. METHODS: We conducted a pair-matching case-control study with 630 ADHD cases and 630 non-ADHD controls 4-12 years of age, matched on the same age, sex, and socioeconomic status. The case and control children were systematically evaluated via structured diagnostic interviews, including caregiver interviews, based on the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., revised criteria (DSM-IV-R). We evaluated the association between BLLs and ADHD using the Pearson chi-square test for categorical variables and the Student t-test for continuous data. We then performed conditional multiple variables logistic regression analyses with backward stepwise selection to predict risk factors for ADHD. RESULTS: There was a significant difference in BLLs between ADHD cases and controls. ADHD cases were more likely to have been exposed to lead during childhood than the non-ADHD control subjects, with adjustment for other known risk factors [children with BLLs >or= 10 microg/dL vs.

Effects of Cd2+ on transient outward and delayed rectifier potassium currents in acutely isolated rat hippocampal CA1 neurons.

The effects of cadmium (Cd(2+)) on the transient outward potassium current (I(A)) and delayed rectifier potassium current (I(K)) were investigated in acutely dissociated rat hippocampal CA1 neurons using the whole-cell patch-clamp technique. The results showed that Cd(2+) inhibited the amplitudes of I(A) and I (K) in a reversible and concentration-dependent manner, with half-maximal inhibitive concentration (IC(50)) values of 546+/-59 and 749+/-53 microM, and the inhibitory effect of Cd(2+) was voltage dependent. Cd(2+) significantly shifted the steady-state activation and inactivation curve of I(A) to more positive potentials. In contrast, Cd(2+) caused a relatively less but still significant positive shift in the activation of I(K) without effect on the inactivation curve. Cd(2+) significantly slowed the recovery from inactivation of I(K) but had no effect on the recovery time course of I(A). The results suggest that the modulation of I(A) and I(K) was most likely mediated by the interaction of Cd(2+) with a specific site on the potassium-channel protein rather than by screening of bulk surface-negative charge. The effects of Cd(2+) on the voltage-gated potassium currents may be a possible contributing mechanism for the Cd(2+)-induced neurotoxic damage. In addition, the effects of Cd(2+) on the potassium currents at concentrations that overlap with its effects on calcium currents raise concerns about its use in pharmacological or physiological studies.

Opposite effects of alpha-lipoic acid on antioxidation and long-term potentiation in control and chronically lead-exposed rats.

Among the developmental changes identified in rats exposed to lead are impairments in long-term potentiation (LTP) in the hippocampus and changes in the levels of reactive oxygen species (ROS) in cells and some soft tissues. alpha-Lipoic acid (LA) has been reported to be highly effective in improving the thiol capacity of the cells and in reducing lead-induced oxidative stress. To explore the effects of LA on LTP in chronically lead-exposed rats and the relationship between ROS and LTP in both control and lead-exposed rats, we have compared LTP and oxidative stress parameters in groups of lead-exposed and control rats with or without LA treatment (10, 25, 50, and 100 mg/kg through intraperitoneal injection). The capacity of LA to decrease hippocampal lead levels in lead-exposed rats was examined. We found that LA had no effects in decreasing the level of lead in the hippocampus, but it did appear to have both antioxidant properties and a reparatory effect on LTP amplitude in rats developmentally exposed to lead for 2 weeks following birth. Interestingly, bell-shaped dose-response curves emerged. In the lower LA dosage groups (10, 25 mg/kg LA), there was an increasing LTP amplitude. The strongest protective effect in terms of the induction and amplitude of LTP in the lead-exposed group with at 25 mg/kg LA; when higher dosages were applied (50, 100 mg/kg LA), the LTP amplitude decreased as compared to the 25 mg/kg LA treatment group. The administration of LA to control animals resulted in a significant impairment of LTP amplitude, with the 100 mg/kg LA treatment having harmful effects on the oxidative parameters. These differential effects of LA on LTP in control and lead-exposed rats may be due to the different redox status of the control and lead-exposed rats.

Effects of EGCG on voltage-gated sodium channels in primary cultures of rat hippocampal CA1 neurons.

(-)-Epigallocatechin-3-gallate (EGCG), the main active component of green tea, is commonly known for its beneficial properties at low doses. On the other hand, little is known about the adverse effects of EGCG. Voltage-gated sodium channel (VGSC) is responsible for both initiation and propagation of action potentials of the neurons in the hippocampus and throughout the central nervous system (CNS). In this study, the effects of EGCG on voltage-gated sodium channel currents (I(Na)) were investigated in rat primary cultures of hippocampal CA1 neurons via the conventional whole-cell patch-clamp technique. We found that I(Na) was not affected by EGCG at the concentration of 0.1microM, but was completely blocked by EGCG at the concentration of 400microM and higher, and EGCG reduced the amplitudes of I(Na) in a concentration-dependent manner in the range of 0.1-400microM. Furthermore, our results also showed that at the concentration of 100microM, EGCG was known to have the following performances: (1) it decreased the activation threshold and the voltage at which the maximum I(Na) current was evoked, caused negative shifts of I(Na) steady-state activation curve. (2) It enlarged I(Na) tail-currents. (3) It induced a left shift of the steady-state inactivation. (4) It reduced fraction of available sodium channels. (5) It delayed the activation of I(Na) in a voltage-dependent manner. (6) It prolonged the time course of the fast inactivation of sodium channels. (7) It accelerated the activity-dependent attenuation of I(Na). On the basis of these findings, we propose that EGCG could impair certain physiological functions of VGSCs, which may contribute, directly or indirectly, to EGCG's effects in CNS.

Effects of Epigallocatechin-3-gallate on lead-induced oxidative damage.

Recent studies have shown that lead (Pb) could disrupt the prooxidant/antioxidant balance of tissue which leads to biochemical and physiological dysfunction. Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is found to be an effective antioxidant. The present study investigated whether EGCG administration could reverse the changes on redox states in rat hippocampus caused by lead exposure. The association between redox status changes and long-term potentiation (LTP) in CA1 area of hippocampus were also examined. Wistar rats exposed to lead from postnatal day 1 were followed by 10 days of EGCG (10, 25 and 50 mg/kg) administration through intraperitoneally (ip), and the rats were sacrificed for experiments at the age of 21-23 days. The experimental results showed that glutathione (GSH) and superoxide dismutase (SOD) activity decreased accompanied with LTP amplitude decrease in CA1 area of hippocampus in the lead-exposed group. EGCG supplementation following lead intoxication resulted in increases in the GSH and SOD levels and increases in the LTP amplitude. Malondialdehyde (MDA) levels, a major lipid peroxidation byproduct, increased following lead exposure and decreased following EGCG treatment. In hippocampal neuron culture model, lead exposure (20 microM) significantly inhibited the viability of neurons which was followed by an accumulation of ROS and a decrease of mitochondrial membrane potential (delta Psi m). Treatment by EGCG (10-50 microM) effectively increased cell viability, decreased ROS formation and improved delta Psi m in hippocampal neurons exposed to lead. These observations suggest that EGCG is a potential complementary agent in the treatment of chronic lead intoxication through its antioxidative character.

[Correlation between schistosomiasis endemic situation and Oncomelania snail status in Yizheng City, Jiangsu province from 2002 to 2011].

OBJECTIVE: To understand the correlation between schistosomiasis endemic situation and Oncomelania snail status, and discuss the control strategy and measures. METHODS: With a retrospective research method, the data were collected and analyzed including the snail area, infected snail area, snail density, density of infected snails, the infection rate of snails, the positive rates of blood tests and stool examinations for schistosomiasis in residents and domestic animals, and the incidence of acute schistosome infection in Yizheng City from 2002 to 2011. The correlation between the infected snails and schistosomiasis was analyzed. RESULTS: There were decline trends in snail area, infected snail area, and schistosomiasis situation. There were positive correlations between the infected snail area and snail area (r = 0.732, P < 0.05), the occurrence of acute schistosomiasis patients and infected snail area (r = 0.678, P < 0.05), and the snail area and schistosome infection rate of residents (r = 0.774, P < 0.05). CONCLUSION: In order to control schistosomiasis, we need to control infected snails, reduce snail areas, and implement comprehensive control measures.

Concentration-dependent effects of fullerenol on cultured hippocampal neuron viability.

BACKGROUND: Recent studies have shown that the biological actions and toxicity of the water-soluble compound, polyhydroxyfullerene (fullerenol), are related to the concentrations present at a particular site of action. This study investigated the effects of different concentrations of fullerenol on cultured rat hippocampal neurons. METHODS AND RESULTS: Fullerenol at low concentrations significantly enhanced hippocampal neuron viability as tested by MTT assay and Hoechst 33342/propidium iodide double stain detection. At high concentrations, fullerenol induced apoptosis confirmed by Comet assay and assessment of caspase proteins. CONCLUSION: These findings suggest that fullerenol promotes cell death and protects against cell damage, depending on the concentration present. The concentration-dependent effects of fullerenol were mainly due to its influence on the reduction-oxidation pathway.

Epigallocatechin-3-gallate induced primary cultures of rat hippocampal neurons death linked to calcium overload and oxidative stress.

Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is the main ingredient of green tea extract. It has been reported that EGCG is a potent antioxidant and beneficial in oxidative stress-related diseases, but others and our previous study showed that EGCG has pro-oxidant effects at high concentration. Thus, in this study, we tried to examine the possible pathway of EGCG-induced cell death in cultures of rat hippocampal neurons. Our results showed that EGCG caused a rapid elevation of intracellular free calcium levels ([Ca(2+)](i)) in a dose-dependent way. Exposure to EGCG dose- and time-dependently increased the production of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (Deltapsi(m)) as well as the Bcl-2/Bax expression ratio. Importantly, acetoxymethyl ester of 5,5'-dimethyl-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, ethylene glycol-bis-(2-aminoethyl)-N,N,N',N'-tetraacetic acid, and vitamin E could attenuate EGCG-induced apoptotic responses, including ROS generation, mitochondrial dysfunction, and finally partially prevented EGCG-induced cell death. Furthermore, treatment of hippocampal neurons with EGCG resulted in an elevation of caspase-3 and caspase-9 activities with no significant accompaniment of lactate dehydrogenase release, which provided further evidence that apoptosis was the dominant mode of EGCG-induced cell death in cultures of hippocampal neurons. Taken together, these findings indicated that EGCG induced hippocampal neuron death through the mitochondrion-dependent pathway.

Wheat germ agglutinin-modified trifunctional nanospheres for cell recognition.

A simple and convenient strategy has been put forward to fabricate smart fluorescent magnetic wheat germ agglutinin-modified trifunctional nanospheres (WGA-TFNS) for recognition of human prostate carcinoma DU-145 cells which are surface-expressed with sialic acid and N-acetylglucosamine. These TFNS can be easily manipulated, tracked, and conveniently used to capture and separate target cells. The presence of wheat germ agglutinin on the surface of WGA-TFNS was confirmed by FTIR, biorecognition of carboxymethyl chitin-modified quantum dots (CM-CT-QDs), and bacterium Staphylococcus aureus. The success in recognizing DU-145 cells by the WGA-TFNS indicates that WGA-TFNS could be applicable.