MiR-29a mediates the apoptotic effects of TNF-α on endothelial cells through inhibiting PI3K/AKT/BCL-2 axis.

Endothelial cell apoptosis driven by inflammation (TNF-α) plays a critical role in the pathogenesis of atherosclerosis, but the exact molecular mechanisms are not clearly elucidated. MicroRNA (miR)-29 families (a/b/c) take important roles in pathophysiological processes of atherosclerosis, also the underlying mechanisms have not been fully clarified. The aims are to explore whether or not miR-29 families mediate the apoptotic effects of TNF-α on endothelial cells and uncover the underlying molecular mechanisms. In this study, MTT assay and flow cytometer analysis were employed respectively to determine the proliferation and apoptosis of human umbilical vascular endothelial cells (HUVECs) under TNF-α exposure. Real-time quantitative PCR and western blot were performed to detect the levels of target RNAs and proteins/their phosphorylation in HUVECs. TNF-α could inhibit HUVEC proliferation and induce HUVEC apoptosis in a positive dose- and time-dependent manner, with a similar way of miR-29a upregulation, but no effects on miR-29b/c. Upregulation of miR-29a with its mimics enhanced the apoptotic effect of TNF-α on HUVECs, but downregulation of miR-29a using anti-miR-29a blocked up its apoptotic effect. MiR-29a inhibited the expression of PI3Kp85α and Bcl-2 and blocked up the signal transduction of PI3K/AKT/Bcl-2 axis to mediate the apoptotic effect of TNF-α on HUVECs. Mediating the inflammation-driven endothelial cell apoptosis is an important biology mechanism by which miR-29a promotes atherosclerosis and its complications. MiR-29a will be a potential diagnostic and therapeutic target for atherosclerotic cardiovascular diseases; it is worthwhile to further study.

Rapid detection of three mycotoxins in animal feed materials using competitive ELISA-based origami microfluidic paper analytical device (µPAD).

We report the development of a competitive ELISA-based origami microfluidic paper-based analytical device (µPAD) for the detection of mycotoxins in animal feed material. The µPAD was patterned using the wax printing technique with the design of a testing pad in the middle and two absorption pads at the side. Anti-mycotoxin antibodies were effectively immobilized on chitosan-glutaraldehyde-modified sample reservoirs in the µPAD. The determination of zearalenone, deoxynivalenol, and T-2 toxin in corn flour was successfully achieved by performing competitive ELISA on the µPAD in 20 min. Colorimetric results were easily distinguished by the naked eye with a detection limit of 1 µg/mL for all three mycotoxins. The µPAD integrated with competitive ELISA holds potential for practical applications in the livestock industry for rapid, sensitive, and cost-effective detection of different mycotoxins in animal feed materials.

The pathophysiological and molecular mechanisms of atmospheric PM2.5 affecting cardiovascular health: A review.

BACKGROUND: Exposure to ambient fine particulate matter (PM2.5, with aerodynamic diameter less than 2.5 µm) is a leading environmental risk factor for global cardiovascular health concern. OBJECTIVE: To provide a roadmap for those new to this field, we reviewed the new insights into the pathophysiological and cellular/molecular mechanisms of PM2.5 responsible for cardiovascular health. MAIN FINDINGS: PM2.5 is able to disrupt multiple physiological barriers integrity and translocate into the systemic circulation and get access to a range of secondary target organs. An ever-growing body of epidemiological and controlled exposure studies has evidenced a causal relationship between PM2.5 exposure and cardiovascular morbidity and mortality. A variety of cellular and molecular biology mechanisms responsible for the detrimental cardiovascular outcomes attributable to PM2.5 exposure have been described, including metabolic activation, oxidative stress, genotoxicity, inflammation, dysregulation of Ca2+ signaling, disturbance of autophagy, and induction of apoptosis, by which PM2.5 exposure impacts the functions and fates of multiple target cells in cardiovascular system or related organs and further alters a series of pathophysiological processes, such as cardiac autonomic nervous system imbalance, increasing blood pressure, metabolic disorder, accelerated atherosclerosis and plaque vulnerability, platelet aggregation and thrombosis, and disruption in cardiac structure and function, ultimately leading to cardiovascular events and death. Therein, oxidative stress and inflammation were suggested to play pivotal roles in those pathophysiological processes. CONCLUSION: Those biology mechanisms have deepen insights into the etiology, course, prevention and treatment of this public health concern, although the underlying mechanisms have not yet been entirely clarified.

Atmospheric PM2.5 blocking up autophagic flux in HUVECs via inhibiting Sntaxin-17 and LAMP2.

Despite of growing evidence linking PM2.5 exposure to autophagic activity in various human cells, the functional significance of PM2.5 exposure affecting autophagy in the pathogenesis of human cardiovascular disease and the underlying molecular mechanisms remain unclear. In this study, the effects of ambient PM2.5 (with final concentration 0, 1, 5, 25 µg/mL) on the autophagic activity in human umbilical vein endothelial cells (HUVECs) were systematically studied. The results showed that the internalized PM2.5 mainly localized in the membrane-surrounded vacuoles in the cytoplasm. Compared with the negative control, dose-dependent increase of autophagosomes, puncta and protein levels of LC3-II and p62, and both dose- and time-dependent increase of AKT phosphorylation, with inversely time-dependent reduction of Beclin 1, ATG3 and ATG5 proteins, were presented in the PM2.5-treated HUVECs, indicating a clear impairment of autophagic degradation in the PM2.5-exposed HUVECs. Meanwhile, increase in lysosomes, LAMP1, proteases of CTSB and CTSD, and protein phosphorylation of ERK1/2 and TFEB was identified in the PM2.5-treated HUVECs, showing a PM2.5-mediated enhancement in lysosomal activity. A novel finding in this study is that both Sntaxin-17 and LAMP2, two key proteins involved in the control of membrane fusion between autophagosome and lysosome, were significantly decreased in the PM2.5-exposed HUVECs, suggesting that the fusion of autophagosome-lysosome was blocked up. Collectively, ambient PM2.5 exposure may block up the autophagic flux in HUVECs through inhibiting the expression of Sntaxin-17 and LAMP2. Autophagic activity in HUVECs is a useful biomarker for assessing risks of environmental factors to human cardiovascular health.

The size-dependent genotoxic potentials of titanium dioxide nanoparticles to endothelial cells.

Despite intensive research activities, there are still many major knowledge gaps over the potential adverse effects of titanium dioxide nanoparticles (TiO2 -NPs), one of the most widely produced and used nanoparticles, on human cardiovascular health and the underlying mechanisms. In the present study, alkaline comet assay and cytokinesis-block micronucleus test were employed to determine the genotoxic potentials of four sizes (100, 50, 30, and 10 nm) of anatase TiO2 -NPs to human umbilical vein endothelial cells (HUVECs) in culture. Also, the intracellular redox statuses were explored through the measurement of the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) with kits, respectively. Meanwhile, the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were also detected by western blot. The results showed that at the exposed levels (1, 5, and 25 µg/mL), all the four sizes of TiO2 -NPs could elicit an increase of both DNA damage and MN frequency in HUVECs in culture, with a positive dose-dependent and negative size-dependent effect relationship (T100 < T50 < T30 < T10). Also, increased levels of intracellular ROS, but decreased levels of GSH, were found in all the TiO2 -NP-treated groups. Intriguingly, a very similar manner of dose-dependent and size-dependent effect relationship was observed between the ROS test and both comet assay and MN test, but contrary to that of GSH assay. Correspondingly, the levels of Nrf2 protein were also elevated in the TiO2 -NP-exposed HUVECs, with an inversely size-dependent effect relationship. These findings indicated that induction of oxidative stress and subsequent genotoxicity might be an important biological mechanism by which TiO2 -NP exposure would cause detrimental effects to human cardiovascular health.

The size-dependent apoptotic effect of titanium dioxide nanoparticles on endothelial cells by the intracellular pathway.

Concerns over the health risk of the widely distributed, commonly used titanium dioxide nanoparticles (nano-TiO2 ) are increasing worldwide. Yet, up-to-now, our understanding in their potential effects on the cardiovascular system is very limited and the toxicological mechanisms are still unclear. In the present study, the CCK-8 assay was performed to determine the cytotoxicity of four sizes (10, 30, 50, and 100 nm) of anatase nano-TiO2 on human umbilical vein endothelial cells (HUVECs) in culture, and the flow cytometry was employed to investigate the potential of these nano-TiO2 to induce the apoptosis of HUVECs. The apoptotic pathway was also probed through the determination of the protein expression and activation of p53, Bax, Bcl-2, caspases-9, -7, -3, and PARP by western blot. The results showed that at the administrative levels (1, 5, 25 µg/mL), all the four sizes of nano-TiO2 could significantly inhibit the viability of HUVECs and elicit significant apoptosis in them, compared with the negative control (P < .05, P < .01). Moreover, the apoptotic rates of HUVECs were increased respectively with the elevating levels and decreasing sizes of the administrative nano-TiO2 , showing a clear dose- and size-dependent effect relationships. Interestingly, the increasing phosphorylation of p53, decreasing ratio of Bcl-2/Bax, and enhancing activation of the downstream proteins caspase-9, -7, -3, and PARP, were also observed with the decreasing sizes of the administrative nano-TiO2 in the western blot, indicating that the intracellular approach of apoptosis, the p53-caspase pathway, is the major way of the nano-TiO2 -mediated apoptosis in HUVECs in culture and that the size is an important parameter that may determine the potential of nano-TiO2 to induce cellular response. In conclusion, these results suggested that high levels of nano-TiO2 exposure may pose potential risks to human cardiovascular health by inducing cardiovascular EC apoptosis.

The health effects of ambient PM2.5 and potential mechanisms.

The impacts of ambient PM2.5 on public health have become great concerns worldwide, especially in the developing countries. Epidemiological and toxicological studies have shown that PM2.5 does not only induce cardiopulmonary disorders and/or impairments, but also contributes to a variety of other adverse health effects, such as driving the initiation and progression of diabetes mellitus and eliciting adverse birth outcomes. Of note, recent findings have demonstrated that PM2.5 may still pose a hazard to public health even at very low levels (far below national standards) of exposure. The proposed underlying mechanisms whereby PM2.5 causes adverse effects to public health include inducing intracellular oxidative stress, mutagenicity/genotoxicity and inflammatory responses. The present review aims to provide an brief overview of new insights into the molecular mechanisms linking ambient PM2.5 exposure and health effects, which were explored with new technologies in recent years.

Role of aryl hydrocarbon receptor in cancer.

Aryl hydrocarbon receptor (AHR), a cytosolic ligand-activated transcription factor, belongs to the member of bHLH/PAS family of heterodimeric transcriptional regulators and is widely expressed in a variety of animal species and humans. Recent animal and human data suggested that AHR is involved in various signaling pathways critical to cell normal homeostasis, which covers multiple aspects of physiology, such as cell proliferation and differentiation, gene regulation, cell motility and migration, inflammation and others. Dysregulation of these physiological processes is known to contribute to events such as tumor initiation, promotion, and progression. Increasing epidemiological and experimental animal data provided substantial support for an association between abnormal AHR function and cancer, implicating AHR may be a novel drug-interfering target for cancers. The proposed underlying mechanisms of its actions in cancer involved multiple aspects, (a) inhibiting the functional expression of the key anti-oncogenes (such as p53 and BRCA1), (b) promoting stem cells transforming and angiogenesis, (c) altering cell survival, proliferation and differentiation by influencing the physiologic processes of cell-cycle, apoptosis, cell contact-inhibition, metabolism and remodel of extracellular matrix, and cell-matrix interaction, (d) cross-talking with the signaling pathways of estrogen receptor and inflammation. This review aims to provide a brief overview of recent investigations into the role of AHR and the underlying mechanisms of its actions in cancer, which were explored by the new technologies emerging in recent years.

Investigating the responses of Cronobacter sakazakii to garlic-drived organosulfur compounds: a systematic study of pathogenic-bacterium injury by use of high-throughput whole-transcriptome sequencing and confocal micro-raman spectroscopy.

We present the results of a study using high-throughput whole-transcriptome sequencing (RNA-seq) and vibrational spectroscopy to characterize and fingerprint pathogenic-bacterium injury under conditions of unfavorable stress. Two garlic-derived organosulfur compounds were found to be highly effective antimicrobial compounds against Cronobacter sakazakii, a leading pathogen associated with invasive infection of infants and causing meningitis, necrotizing entercolitis, and bacteremia. RNA-seq shows changes in gene expression patterns and transcriptomic response, while confocal micro-Raman spectroscopy characterizes macromolecular changes in the bacterial cell resulting from this chemical stress. RNA-seq analyses showed that the bacterial response to ajoene differed from the response to diallyl sulfide. Specifically, ajoene caused downregulation of motility-related genes, while diallyl sulfide treatment caused an increased expression of cell wall synthesis genes. Confocal micro-Raman spectroscopy revealed that the two compounds appear to have the same phase I antimicrobial mechanism of binding to thiol-containing proteins/enzymes in bacterial cells generating a disulfide stretching band but different phase II antimicrobial mechanisms, showing alterations in the secondary structures of proteins in two different ways. Diallyl sulfide primarily altered the α-helix and ß-sheet, as reflected in changes in amide I, while ajoene altered the structures containing phenylalanine and tyrosine. Bayesian probability analysis validated the ability of principal component analysis to differentiate treated and control C. sakazakii cells. Scanning electron microscopy confirmed cell injury, showing significant morphological variations in cells following treatments by these two compounds. Findings from this study aid in the development of effective intervention strategies to reduce the risk of C. sakazakii contamination in the food production environment and on food contact surfaces, reducing the risks to susceptible consumers.

Development of a smartphone-integrated microfluidic paper-based optosensing platform coupled with molecular imprinting technique for in-situ determination of histamine in canned tuna.

We reported the development of a smartphone-integrated microfluidic paper-based optosensing platform for in-situ detection and quantification of histamine in canned tuna. Molecularly imprinted polymers were synthesized via precipitation polymerization and utilized as dispersive solid phase extraction sorbent to selectively extract histamine from canned tuna. Carbon quantum dots functioning as a fluorescent probe were synthesized and introduced onto the microzones of the microfluidic paper device. This facilitated a noticeable fluorescence color change from dark red to vivid blue upon the addition of histamine. The change in fluorescence on the paper device was converted into specific RGB values using a portable UV light box combined with a smartphone. This assay achieved the limit of detection of 14.04 mg/kg with the linear range from 20 to 100 mg/kg of histamine in canned tuna. The entire molecular imprinting-microfluidic optosensing test could be completed in 45 min including sample preparation.

Cytokines-activated nuclear IKKα-FAT10 pathway induces breast cancer tamoxifen-resistance.

Endocrine therapy that blocks estrogen signaling is the most effective treatment for patients with estrogen receptor positive (ER+) breast cancer. However, the efficacy of agents such as tamoxifen (Tam) is often compromised by the development of resistance. Here we report that cytokines-activated nuclear IKKα confers Tam resistance to ER+ breast cancer by inducing the expression of FAT10, and that the expression of FAT10 and nuclear IKKα in primary ER+ human breast cancer was correlated with lymphotoxin ß (LTB) expression and significantly associated with relapse and metastasis in patients treated with adjuvant mono-Tam. IKKα activation or enforced FAT10 expression promotes Tam-resistance while loss of IKKα or FAT10 augments Tam sensitivity. The induction of FAT10 by IKKα is mediated by the transcription factor Pax5, and coordinated via an IKKα-p53-miR-23a circuit in which activation of IKKα attenuates p53-directed repression of FAT10. Thus, our findings establish IKKα-to-FAT10 pathway as a new therapeutic target for the treatment of Tam-resistant ER+ breast cancer.

Raman spectroscopy: Principles and recent applications in food safety.

Food contaminant is a significant issue because of the adverse effects on human health and economy. Traditional detection methods such as liquid chromatography-mass spectroscopy for detecting food contaminants are expensive and time-consuming, and require highly-trained personnel and complicated sample pretreatment. Raman spectroscopy is an advanced analytical technique in a manner of non-destructive, rapid, cost-effective, and ultrasensitive sensing various hazards in agri-foods. In this chapter, we summarized the principle of Raman spectroscopy and surface enhanced Raman spectroscopy, the methods to process Raman spectra, the recent applications of Raman/SERS (surface-enhanced Raman spectroscopy) in detecting chemical contaminants (e.g., pesticides, antibiotics, mycotoxins, heavy metals, and food adulterants) and microbiological hazards (e.g., Salmonella, Campylobacter, Shiga toxigenic E. coli, Listeria, and Staphylococcus aureus) in foods.

Rapid determination of thiram on apple using a flexible bacterial cellulose-based SERS substrate.

A flexible nanocomposite composed of bacterial cellulose (BC) and gold nanoparticles (AuNPs) was developed as a SERS substrate to determine thiram on apple surface by two collection methods namely "paste-and-peel" and "wiping". Enhancement factor of this SERS substrate for sensing thiram residues was determined to be 2.8 × 105. Compared to the benchtop Raman spectrometer, portable Raman spectroscopic device showed a lower sensitivity towards thiram residues with limit of detection at 0.98 ppm, satisfying maximum residue level of thiram on apple required by both Europe and America. A good linear correlation of SERS peak intensity at 1368 cm-1 and different concentrations of thiram (1-50 ppm) revealed a coefficient up to 0.99. This flexible BC-based SERS substrate has a great analytical performance in sensitivity, reproducibility and stability, and is suitable for rapid detection (<8 min) and quantitative analysis of pesticides on food surface.

SiNPs induce ferroptosis in HUVECs through p38 inhibiting NrF2 pathway.

Introduction: Despite of growing evidence linking silica nanoparticles (SiNPs), one of the global-top-three-produced and -used nanoparticle (NP), to human health risks, there remain many knowledge gaps over the adverse effects of SiNPs exposure on cardiovascular system and the underlying molecular mechanisms. Methods: In this study, the ferroptotic effects of SiNPs (20 nm; 0, 25, 50, and 100 µg/mL) on human umbilical vein endothelial cells (HUVECs) and the possible molecular mechanism were studied with the corresponding biochemical and molecular biology assays. Results and discussion: The results showed that at the tested concentrations, SiNPs could decrease HUVEC viability, but the deferoxamine mesylate (an iron ion chelator) might rescue this reduction of cell viability. Also, increased levels of intracellular reactive oxygen species and enhanced mRNA expression of lipid oxidation enzymes (ACSL4 and LPCAT3) with increase in lipid peroxidation (malondialdehyde), but decreased ratios of intracellular GSH/total-GSH and mitochondrial membrane potential as well as reduced enzymatic activities of anti-oxidative enzymes (CAT, SOD, and GSH-PX), were found in the SiNPs-treated HUVECs. Meanwhile, increase in p38 protein phosphorylation and decrease in NrF2 protein phosphorylation with reduced mRNA expressions of downstream anti-oxidative enzyme genes (CAT, SOD1, GSH-PX, and GPX4) was identified in the SiNPs-exposed HUVECs. These data indicated that SiNPs exposure might induce ferroptosis in HUVECs via p38 inhibiting NrF2 pathway. Ferroptosis of HUVECs will become a useful biomarker for assessing the cardiovascular health risks of environmental contaminants.

Genotoxicity of the sediments collected from Pearl River in China and their polycyclic aromatic hydrocarbons (PAHs) and heavy metals.

The accelerated industrialization and urbanization in the last three decades around the Pearl River Delta within Guangdong Province in China have led to serious concerns about the impacts on the aquatic environment. In the present study, the genotoxicity of the sediments collected from the Pearl River was evaluated by micronucleus (MN) assay with Vicia faba root tip cells, and the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs, including Cr, Cu, As, Se, Cd, Hg, and Pb) in the sediments were determined respectively by GC-MS, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectrometry. The results showed that there were significant increases of MN frequencies observed in the sediment-exposed groups, compared with the negative group (P < 0.05, P < 0.01), indicating that the sediments clearly had genotoxicity to the V. faba root cells. The total concentrations of the priority PAHs (250-13,656 ng g(-1), dry weight) and HMs (As, 22,770-36,639 µg kg(-1); Cr, 39,333-133,343 µg kg(-1); Cu, 36,145-159,270 µg kg(-1); Pb, 51,210-166,642 µg kg(-1); Cd, 475.4-1,818.9 µg kg(-1); Hg, 59.9-460.8 µg kg(-1); and Se, 331.7-1,250.4 µg kg(-1), dry weight) were close to those obtained from other urbanized and industrialized areas, which have been considered moderately polluted. There was a clear positive correlation between MN potency and the molar concentrations of Hg and Pb in the sediments (Hg, r = 0.94; Pb, r = 0.91), suggesting that Hg and Pb were the most important factors that posed the sediments higher genotoxicity to V. faba root cells. Our results suggested that both biological and chemical approaches are necessary to be included in a battery of tests to assess the eco-environmental risks of sediments.

Molecularly imprinted core-shell Au nanoparticles for 2,4-dichlorophenoxyacetic acid detection in milk using surface-enhanced Raman spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) has been extensively investigated for rapid and sensitive detection of trace level chemical contaminants in foods. Lack of selectivity to the targeted molecules in food matrices and fairly poor spectral reproducibility remain the main challenges for practical SERS applications. Herein, an ingenious strategy was proposed to hybridize molecularly imprinted polymers (MIPs) with gold nanoparticles as the functional SERS substrate for selective separation and detection of 2,4-dichlorophenoxyacetic acid (2,4-D), a systemic herbicide that has acute toxicity and potential cancer risk. The core-shell AuNPs@MIPs nanoparticles were finely tailored by wrapping an ultrathin layer of MIPs shell on the surface of AuNPs, which allowed selectively separating and enriching 2,4-D to the near surface of AuNPs and ensured the enhancement of Raman scattering signal of the analyte. Embedding an internal standard (i.e., 4-aminothiophenol) inside AuNPs@MIPs for SERS spectral calibration improved the quantification accuracy for 2,4-D. Three-dimensional finite difference time domain (3D-FDTD) simulation demonstrated the maximal electric field enhancement presented in the gap between adjacent AuNPs@MIPs with the theoretical enhancement factor (EF) as high as 5.85 × 106. Chemometric models established using SERS spectra showed accurate differentiation and quantification results for 2,4-D in milk at various contamination levels with a limit of detection (LOD) of 0.011 µg/mL. Our approach to integrate MIPs with noble metallic nanoparticles has great potential for selective and quantitative detection of analytes using SERS for practical agri-food analysis.

Molecularly Imprinted Polymers Coupled with Surface-Enhanced Raman Spectroscopy to Detect Chemical Hazards in Foods.

Preparation of molecularly imprinted polymers coupled with surface-enhanced Raman spectroscopy (MIP-SERS) sensor and its application in detecting chemical hazards in food matrices are described. Sample cleaning is achieved by molecularly imprinted solid-phase extraction (MISPE), and target molecules are detected by SERS. Procedures of MIP synthesis, MISPE preparation, SERS substrate preparation, spectral collection, data analysis, and food analysis application are described.

Rapid determination of atrazine in apple juice using molecularly imprinted polymers coupled with gold nanoparticles-colorimetric/SERS dual chemosensor.

Rapid and reliable determination of atrazine, a common chemical contaminant, in agri-foods is highly necessary. We reported a novel dual-chemosensor coupling, a separation [molecularly imprinted polymers (MIPs)], an instrumental-free detection [gold nanoparticles (AuNPs)-based colorimetric assay] and an instrument-based quantification [surface enhanced Raman spectroscopy (SERS)] method for high-throughput and sensitive determination of atrazine in apple juice. Used as the selective sorbent for the solid phase extraction, MIPs effectively extracted atrazine from apple juice with high recoveries (∼93%). AuNPs of different sizes (large; medium; and small) performed differently in the two analytical methods. Large-AuNPs provided the highest sensitivity in colorimetric analysis (<0.01 mg L-1), while medium-AuNPs achieved the lowest limit of detection (0.0012 mg L-1) and quantification (0.0040 mg L-1) in SERS analysis. With minor modifications, protocols for both analytical methods can rapidly detect and/or quantify atrazine in different food products complying with the Health Canada regulation (0.005 mg L-1).

The size-dependent genotoxicity and oxidative stress of silica nanoparticles on endothelial cells.

Concerns over the health risk of the widely distributed, commonly used silica nanoparticles (SiNPs) are increasing worldwide. Yet, up to now, there are still many major knowledge gaps over the potential adverse effects of SiNP exposure on human cardiovascular health and the underlying mechanisms. In this study, comet assay and micronucleus test were employed to determine the genotoxic potentials of four sizes (10, 25, 50, 100 nm) of SiNPs to human umbilical vein endothelial cells (HUVECs) in culture. The intracellular redox statuses were explored through the determination of the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) with kits, respectively. The protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were also detected by Western blot. The results showed that at the administrative levels (1, 5, 25 µg/mL), all the four sizes of SiNPs could induce an increase of both DNA damages and MN frequencies in HUVECs in culture, with a positive dose- and negative size-dependent effect relationship (S100 < S50 < S25 < S10). Also, significantly enhanced levels of intracellular ROS, but decreased levels of GSH, were observed in the SiNP-treated groups. Interestingly, a very similar manner of dose- and size-dependent effect relationship was observed between the ROS test and both comet assay and MN test, but contrary to that of GSH assay. Correspondingly, the levels of Nrf2 protein were also enhanced in the SiNP-treated HUVECs, with a negative size-dependent effect relationship. These results implicated that induction of oxidative stress and subsequent genotoxicity may be an important biological mechanism by which SiNP exposure may affect human cardiovascular health.

Genotoxicity of total and fractionated extractable organic matter in fine air particulate matter from urban Guangzhou: comparison between haze and nonhaze episodes.

To investigate the genotoxic potencies of extractable organic matter (EOM) in aerosols, fine air particulate matter (PM(2.5)) was collected simultaneously at a roadside (1.2 m above ground) and at a rooftop location (50 m above ground) in urban Guangzhou (China) during a nonhaze period in September 2006 and a haze period in October 2006. Particle-bound organics were extracted and separated into aliphatic, aromatic, and polar fractions. The genotoxicity of total and fractionated extracts were tested by single-cell electrophoresis (comet assay) with human blood lymphocytes. The PM(2.5) concentrations usually exceeded the U.S. National Ambient Air-Quality Standard level (65 microg/m(3)) at both the roadside and the rooftop. During nonhaze days, the roadside samples showed substantially higher PM(2.5) levels (108-130 microg/m(3)) and significantly higher genotoxic effects of total and fractionated EOM (p < 0.05 for >10 m(3) air equivalent/ml) than the rooftop samples. During haze days, however, PM(2.5) levels and genotoxic potencies of rooftop samples were drastically elevated and comparable to those of roadside samples, implying that during haze episodes, most people in the urban area are exposed to PM(2.5) pollution as serious as in the heavily polluted roadside microenvironment. All total EOM samples showed significant (p < 0.05) dose-response effects, and their effects as olive tail moment were less than the sums of the three fractions. Aromatic fractions of EOM exhibited the greatest genotoxic potencies, but polar fractions also contributed substantially to DNA-damaging effects. Polycyclic aromatic hydrocarbons and nitrated derivatives likely are the most important species responsible for the genotoxicity of EOM in PM(2.5).