Associations between serum polychlorinated biphenyls, halogen flame retardants, and renal function indexes in residents of an e-waste recycling area.

E-waste handling activities release large quantities of polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) into the surrounding area, creating a high exposure risk for local residents. However, the possibility of PCBs and HFRs exposure contributing to renal injury has not been extensively studied. To fill this knowledge gap, we conducted an epidemiological analysis of adolescents and adults recruited from an e-waste recycling area and a control area. Some PCBs and HFRs compounds were statistically significantly associated with the levels of ß2-microglobulin (ß2-MG), blood urea nitrogen (BUN), serum creatinine (SCr), and uric acid, with thyroid hormone-related genes found to partly mediate these associations. The interactions of PCBs and HFRs with metals also influenced renal function indexes. Exposure to high concentrations of PCBs and HFRs resulted in higher levels of ß2-MG and lower levels of BUN and SCr in the exposed group. As indicated by the elevated ß2-MG levels, high exposure to PCBs and HFRs may increase the risk of early renal injury for adolescents. These findings help to clarify the impacts of PCBs and HFRs on renal function and highlight the need to protect the health of residents in regions impacted by e-waste handling activities.

Contribution of heavy metals in PM2.5 to cardiovascular disease mortality risk, a case study in Guangzhou, China.

Heavy metals play an important role in inducing fine particulate matter (PM2.5) related cardiovascular disease (CVD). However, most of the past researches concerned the associations between CVD mortality and the PM2.5 mass, which may not reveal the CVD mortality risk contributed by heavy metals in PM2.5. This study explored the correlations between individual heavy metals in PM2.5 and CVD mortality, identified the heavy metals that significantly contribute to PM2.5-related CVD, heart disease (HD), and cerebrovascular disease (CEV) mortality, and attempted to establish corresponding source control measures. Over a 2-year study period, PM2.5 was sampled daily in Guangzhou, China and analyzed for heavy metals. The airborne pollution and weather data, along with CVD, HD, and CEV mortality, were obtained at the same time. The excess risk (ER) of mortality was linked to the individual heavy metals using a distributed lag non-linear model. PM2.5 and most heavy metals showed significant correlations with the CVD, HD, and CEV mortality; the largest cumulative ER (LCER) values of CVD mortality associated with an interquartile range increase in the levels of lead, cadmium, arsenic, selenium, antimony, nickel, thallium, aluminum, iron, and PM2.5 were 2.43%, 2.23%, 1.66%, 2.39%, 1.19%, 1.21%, 2.69%, 3.29%, 1.74%, and 2.40%, respectively. Most heavy metals showed comparable LCER values of HD and CEV mortality. Heavy metals with the addition of PM2.5 were divided into three groups following their LCER values; lead, cadmium, arsenic, antimony, thallium, zinc, aluminum, and iron, whose contributions were greater than or equal to the average effect of the PM2.5 components, should be limited on a priority basis. These findings indicated that heavy metals play roles in the CVD, HD, and CEV mortality risk of PM2.5, and specific control measures which aimed at the emission sources should be taken to reduce the CVD mortality risk of PM2.5.

Changes in thyroid hormone related proteins and gene expression induced by polychlorinated biphenyls and halogen flame retardants exposure of children in a Chinese e-waste recycling area.

Polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) are major pollutants in e-waste recycling area. High internal exposure levels of PCBs and HFRs are harmful to human thyroid hormone (TH) equilibrium. To examine their disrupting effects on TH, we conducted a study on children (n = 114) of an e-waste recycling and a control area in South China. Concentrations of PCBs, HFRs, and TH levels were determined in serum samples. TH related proteins and their corresponding gene were also monitored as markers of such disruption. Levels of these chemicals in the exposed group were much greater than those in the control group. Results of the linear regression and generalized additive model indicated the presence of close relationships between the internal exposure levels and the responses of TH related proteins, gene expression. More extensive exposure concentrations of these chemicals led to higher expression of iodothyronine deiodinase I and decreased the concentrations of thyroid-stimulating hormone, expression of TH receptor α, indicating the exertion of discrepant and even contrary influences on equilibrium of TH, and a compensation of these mechanisms may kept the homeostasis of TH. These results for children warrant further investigation on the health risks of PCBs and HFRs exposure in e-waste area.

Disruption of thyroid hormone regulated proteins and gene expression by polychlorinated biphenyls, polybrominated diphenyl ethers and new flame retardants in residents of an e-waste region.

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and new flame retardants (NFRs) are known thyroid hormone (TH) disruptors, but their disrupting mechanisms in humans are not completely understood. In this study, we aimed to explore the disrupting mechanisms of the aforementioned chemicals via examining TH-regulated proteins and gene expression in human serum. Adult participants from an e-waste dismantling (exposed group) and a control region (control group) in South China provided blood samples for the research. Some compounds of PCBs, PBDEs, and NFRs showed strong binding affinity to the thyroid-stimulating hormone (TSH), thyroglobulin, thyroxine-binding globulin (TBG), gene expression of TH receptor α (TRα) and ß, and iodothyronine deiodinase I (ID1). The highly exposed individuals had lower levels of TBG, TSH, and expression of TRα, but higher expression of ID1 than those of the control group. The disruption of TH-regulated proteins and gene expression suggested the exertion of different and, at times, even contradictory effects on TH disruption. However, no statistically significant difference was found in the TH levels between the exposed and the control group, implying that the TH disruption induced by these chemicals depends on the combined influence of multiple mechanisms. Gene expression appears to be an effective approach for investigations of TH disruption and the potential health effects.

Human Sex Hormone Disrupting Effects of New Flame Retardants and Their Interactions with Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, a Case Study in South China.

Even though sex hormone disrupting effects of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are widely understood, similar effects associated with new flame retardants (NFRs) have not been so well studied. This study aimed to explore the sex hormone disruption of NFRs and their interactions with PCBs and PBDEs through the conduct of an ecological study in an e-waste dismantling and control region in South China. Questionnaires and blood samples were collected from local adult residents. Results of generalized additive model and linear regression analyses indicate that several species of NFRs showed similar disrupting effects with PBDE congeners on female follicle-stimulating hormone (FSH) and male testosterone. Judged by the curved shape and statistical significance, ΣNFR (sum of 8 species of NFRs) showed stronger disrupting effects on male testosterone and female FSH compared to ΣPBDE (sum of 13 congeners of PBDEs). The interactions induced by NFRs complicated the original sex hormone disruption led by PCBs and PBDEs. The disrupting effects and interactions induced by NFRs decreased female FSH levels in the exposed group. Comprehensive evaluation is needed to provide the evidence base for judging the health risks arising from the increased usage of NFRs.

Association between serum polybrominated diphenyl ethers, new flame retardants and thyroid hormone levels for school students near a petrochemical complex, South China.

As surrogates of polybrominated diphenyl ethers (PBDEs), new flame retardants (NFRs) include a series of chlorinated and brominated flame retardants. Though the NFRs are thought to induce similar thyroid hormone (TH) disrupting effects as PBDEs, few studies have focused on them. Given the increasing levels of NFRs in the environment, more in depth investigation of the potential TH disrupting effects of NFRs is warranted. This research involved a health survey to collect data and examine the associations between PBDEs, NFRs and TH. 174 school students lived near a petrochemical complex in South China participated in the survey, completing questionnaires and providing blood samples. Thirteen congeners of PBDEs, eight species of NFRs, TH and thyroid-stimulating hormone (TSH) were measured. The median levels of ΣPBDE (sum of thirteen congeners of PBDEs) and ΣNFR (sum of eight species of NFRs) for students were 140 and 240 ng g-1 lipid, respectively. Nonmonotonic relationships were observed between quartile levels of PBDEs, NFRs and corresponding TH. In contrast to ΣPBDE that was positively associated with triidothyrine (T3) level, ΣNFR was not statistically associated with TH. ΣPBDE + NFR (sum of thirteen congeners of PBDEs and eight species of NFRs) was significantly associated with T3 level.

Gas chromatography-mass spectrometry determination of earthy-musty odorous compounds in waters by two phase hollow-fiber liquid-phase microextraction using polyvinylidene fluoride fibers.

A rapid and sensitive method for the determination of earthy-musty odorous compounds, 2-methylisoborneol, 2-isopropyl-3-methoxy pyrazine, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, and geosmin, in water samples has been developed. The method was based on coupling a new polyvinylidene fluoride (PVDF) hollow-fiber liquid-phase microextraction system with gas chromatography-mass spectrometry (GC-MS). The PVDF hollow fibers have high porosity and an enhanced solvent compatibility for extraction of the target analytes. Experimental conditions were optimized by investigating the type of extraction solvent, sample pH, sodium chloride concentration, stirring speed, extraction time, and GC-MS conditions. Under optimized conditions, the earthy-musty odorous compounds exhibited good linearity (R>0.995) in the concentration range of 6.2-250ng/L. The repeatability and reproducibility of the method were lower than 6.8% and 9.8%, respectively. The limit of detection and limit of quantification values were lower than 2.0 and 6.2ng/L, respectively. The analysis of different water samples such as tap, pond, rive and waste water indicated minimal matrix effects. Analyte recoveries for real samples spiked at different concentrations were between 84.4% and 117.5%.

Rapid analysis of cyclamate in foods and beverages by gas chromatography-electron capture detector (GC-ECD).

A rapid method for determination of sodium cyclamate in foods and beverages was developed. Sodium cyclamate was converted to N,N-dichloridecyclohexylamine by reaction with sodium hypochlorite under acid condition. N,N-dichloridecyclohexylamine was subsequently extracted by n-hexane and determined by gas chromatography. Conditions such as derivatization time, the concentration of sodium hypochlorite and sulphuric acid were optimised. Amino acids, aliphatic amines, and food additives such as preservatives, dyes and sweeteners showed no interference for quantification of cyclamate. The correlation coefficient of calibration curve was 0.9993 in the range of 5.0-250mg/L. The limits of detection (LOD) and limits of quantification (LOQ) were calculated as three or ten times the signal-to-noise ratio (S/N), respectively. The LOD and LOQ for yellow wine and fruit juice were 0.05 and 0.2mg/L, respectively. The LOD and LOQ for cake and preserved fruit were 0.25 and 0.8mg/kg, respectively. The intra-day and inter-day RSD were 0.28% and 1.1% (n=5), respectively. The method was successfully applied for determination of cyclamate in yellow wine, cake, fruit juice and preserved fruit. This method was simple, fast, and sensitive. It was suitable for the determination of cyclamate in foods and beverages for safety and quality control inspections.

Bacterial melanin interacts with double-stranded DNA with high affinity and may inhibit cell metabolism in vivo.

Melanin has been found to interact with a number of molecules including metal ions, antibiotics and proteins. In this study, we showed how melanin from bacteria can interact with double-stranded DNA. Investigation using capillary electrophoresis, various spectroscopic techniques and circular dichroism found that melanin interacts with DNA by intercalating between the base pairs of DNA. And this was further supported by simulating different forms of melanin docking to oligonucleotides. Transmission electron microscopy of recombinant Escherichia coli producing melanin suggested the interaction in vivo. Furthermore, we showed how the cytoplasmic localization of melanin may provide a novel function in inhibiting cellular metabolism using microcalorimetry. The implications of the interaction in prokaryotes and eukaryotes were discussed.

Extraction of genomic DNA using a new amino silica monolithic column.

A new amino silica monolithic column was developed for DNA extraction in a miniaturized format. The monolithic column was prepared in situ by polymerization of tetraethoxysilane (TEOS) and N-(beta-aminoethyl)-gamma-aminopropylmethyldimethoxysilane (AEAPMDMS). DNA was loaded in 50 mM tris(hydroxylmethyl)aminomethane-EDTA buffer at pH 7.0 and eluted with 300 mM potassium phosphate solution at pH 10.0. Under optimal condition, a 6.0-cm monolithic column provided a capacity of 56 ng DNA with an extraction efficiency of 71 +/- 5.2% (X +/- RSD). When the amino silica monolithic column was applied to extract genomic DNA from the whole blood of crucian carp, an extraction efficiency of 52 +/- 5.6% (X +/- RSD) was obtained by three extractions. Since the chaotropic-based sample loading and organic solvent wash steps were avoided in this procedure, the purified DNA was suitable for downstream processes such as PCR. This amino silica monolithic column was demonstrated to allow rapid and efficient DNA purification in microscale.

Rapid recovery of DNA from agarose gel slices by coupling electroelution with monolithic SPE.

An amino silica monolithic column prepared by in situ polymerization of tetraethoxysilane and N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane was firstly applied to recover DNA from agarose gel slices by coupling electroelution with monolithic SPE. DNA was electroeluted from the agarose gel slices onto the amino silica monolithic column. The DNA adsorbed on this monolithic column was then recovered using sodium phosphate solution at pH 10. The whole recovery procedure could be completed within 10 min because the use of amino silica monolithic column accelerated the DNA capture and facilitated the DNA release. Electroelution conditions, such as buffer pH, buffer concentration and applied voltage, were online optimized. The average yield for herring sperm DNA, pBR 322 DNA and lambda DNA recovered from 1.0% w/v agarose gel slices were 55+/-4, 50+/-6 and 42+/-7% (n=3), respectively. The polymerase chain reaction performance of pGM plasmid recovered from agarose gel slices demonstrated that the method could provide high-quality DNA for downstream processes. The combination of electroelution with monolithic SPE allows a rapid, simple and efficient DNA recovery method. This technique is especially useful for applications that need to purify small starting amounts of DNA.

Application of a new hybrid organic-inorganic monolithic column for efficient deoxyribonucleic acid purification.

A new hybrid organic-inorganic monolithic column for efficient deoxyribonucleic acid (DNA) extraction was prepared in situ by polymerization of N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane (AEAPTES) and tetraethoxysilane (TEOS). The main extraction mechanism was based on the Coulombic force between DNA and the amino silica hybrid monolithic column. DNA extraction conditions, such as pH, ion concentration and type, and loading capacity, were optimized online by capillary electrophoresis with laser-induced fluorescence detection. Under optimal condition, a 6.0-cm monolithic column provided a capacity of 48 ng DNA with an extraction efficiency of 74+/-6.3% (X+/-RSD). The DNA extraction process on this monolithic column was carried out in a totally aqueous system for the successful purification of DNA and removal of proteins. The PBE2 plasmid could be extracted from Bacillus subtilis (B. subtilis) crude lysate within 25 min, and the purified DNA was suitable for the amplification of a target fragment by polymerase chain reaction. This study demonstrates a new attractive solid-phase support for DNA extraction to meet the increasingly miniaturized and automated trends of genetic analyses.

Protective action of bacterial melanin against DNA damage in full UV spectrums by a sensitive plasmid-based noncellular system.

The purpose of this study was to introduce a simple and sensitive plasmid-based noncellular system to evaluate the photoprotection of bacterial melanin on DNA damage against ultraviolet (UV) radiation. Plasmid DNA was used to assess the role of melanin in different ranges of UV using a series of in vitro assays. Fluorometric measurements suggested that melanin could efficiently scavenge reactive oxygen species (ROS) generated by UVA irradiation in solution, and the scavenging capability was proportional to the pigment concentration. The protective effect of melanin on plasmid DNA under UVB irradiation was confirmed by the transformation efficiency of the protected DNA, which was at least 10-fold higher than that of the non melanin protected DNA. After the UVC irradiation, the DNA damage of strand breaks was quantified by laser-induced fluorescence capillary electrophoresis. The percentage of supercoiled plasmid was reduced from 80% to less than 5% without melanin protection. In contrast, the percentage of supercoiled DNA only decreased to about 40% in the presence of melanin under the same radiation conditions. All these results demonstrated that bacterial melanin did protect DNA from being damaged throughout full UV irradiation. This system, avoiding the potential interference by cellular DNA repair machinery and intracellular substances, may provide a sensitive in vitro means to evaluate the functions of melanin and other photoprotective compounds from different sources.

New hydroxyapatite monolithic column for DNA extraction and its application in the purification of Bacillus subtilis crude lysate.

A hydroxyapatite (Hap) monolithic column with micrometer macropores skeleton structure was prepared by sol-gel technique for efficient DNA extraction. The main extraction mechanism of this monolithic column was attributed to the electrostatic interaction between the phosphate groups of DNA and the calcium ions (C site) of Hap. DNA extraction conditions, such as pH, ion concentration, ion type and loading capacity, on the monolithic column were optimized online by capillary electrophoresis with laser-induced fluorescence detection. Under the optimal condition, a 6 cm length monolithic column provided a capacity of 40 ng DNA with an extraction efficiency of 64+/-6.2% (X+/-RSD). As low concentration of salts were used in the extraction procedure, the purified PBE2 plasmid from the Bacillus subtilis crude lysate could be amplified by polymerase chain reaction. This result illustrated that Hap was a potential matrix for DNA purification from complex biological samples which was compatible with the subsequent genetic analysis in miniature format. Since the preparation of this monolithic column was very simple, it was possible to integrate this novel matrix with chip to allow rapid and efficient DNA purification in microscale. This study provided a new attractive solid-phase support for DNA extraction to meet the miniaturized and automated trends of genetic analysis.

Analysis of plasmid DNA damage induced by melanin with capillary electrophoresis.

Dilute linear poly(N-isopropylacrylamide) (PNIPAM) in Tris-Mes-EDTA (TME) buffer was used as sieving matrix for capillary electrophoresis (CE) of plasmid DNA and plasmid topological isomers induced by melanin in uncoated capillary. At the optimized condition of 0.1% (w/v) PNIPAM in TME buffer, base line separation of the plasmid DNA ladder (2-12 kbp) was achieved within 15 min. Three positive clones with inserts of 468, 1147 and 1566 bp can be distinguished from the plasmid pUC 18 vector within 13 min. The migration order of the plasmid topological isomers in the dynamic coating matrix was confirmed by the enzymatically prepared and UV-induced plasmids. The covalently closed circular form appeared firstly, followed by the linear plasmid form and then the open circular form. The effect of bacterial melanin obtained from Pseudomonas maltophilia AT18 on plasmid pUC 18 was investigated by CE in uncoated capillary in vitro. Plasmid pUC 18 incubated with either melanin or copper ions alone sustained little DNA damage. The combination of melanin with Cu(II) can cause the plasmid pUC 18 conformational changes from covalently closed circular form to open form. Understanding the damage effect of melanin with copper ions on DNA would be important for the melanin-related application, such as photoprotective antioxidant in protecting the skin from cancer, pathophysiology research in clinic. The investigation of melanin induced plasmid conformational changes by CE in uncoated capillary also revealed that the application of the dynamic coating matrix could be extended to the study of plasmid conformational changes in other plasmid-based biological technologies.

pH effect on dynamic coating for capillary electrophoresis of DNA.

A buffer consisting of tris(hydroxymethyl)aminomethane, 2-(N-moropholino)ethanesulfonic acid (Mes) and EDTA with constant ion strength was used to investigate the effect of buffer pH on the dynamic coating behavior of poly(N-isopropylacrylamide) (PNIPAM) for DNA separation. The atomic force microscopy (AFM) image illustrated that PNIPAM in lower-pH buffer was much more efficient in covering a silica wafer than that in higher-pH buffer. The coating performance of PNIPAM was also quantitatively analyzed by Fourier transform IR attenuated total reflectance spectroscopy and by measuring the electroosmotic flow (EOF). These results indicated that the stability of the dynamic coating was dependent on the pH of the sieving matrix and was improved by reducing the pH to the weak-acid range. The lower pH of the sieving buffer may induce the polymer more efficiently to adsorb on the capillary wall to suppress EOF and DNA-capillary wall interaction for DNA separation. The enhanced dynamic coating capacity of PNIPAM in lower-pH buffer may be attributed to the hydrogen bonds between the hydroxyl groups of the silica surface and the oxygen atom of the carbonyl groups of PNIPAM.

Electrophoretic separation of DNA using a new matrix in uncoated capillaries.

A new separation matrix, consisting of polymer poly(N-isopropylacrylamide) (PNIPAM) and small molecule additive mannitol, was used for double-stranded (ds) DNA and plasmid DNA separation by capillary electrophoresis. The matrix had a low viscosity, which made it very easy to handle. The additive mannitol dramatically enhanced the sieving performance of PNIPAM in TBE buffer. The optimal mannitol concentration 6% in polymer solution, was determined with the consideration of both speed and resolution. A resolution of 0.95 was achieved on the separation of 271/281 bp in the phiX174/HaeIII digest by using 1.5% PNIPAM + 6% mannitol, while the supercoiled, linear and nicked conformers of lambda plasmid were separated in 1% PNIPAM + 6% mannitol, demonstrating the potential use of this new matrix for effective DNA separations. The dramatic impact of mannitol on sieving performance of PNIPAM solution was investigated. pH dependent self-coating ability of PNIPAM was revealed. The presence of mannitol in TBE buffer decreased the pH of the buffer, which led to more efficient self-coating ability of PNIPAM probable due to the formation of hydrogen bonds between PNIPAM molecules and silanol groups at the silica wall.