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Arsenic is a well-known environmental carcinogen and chronic exposure to arsenic through drinking water has been reported to cause skin, bladder and lung cancers, with arsenic metabolites being implicated in the pathogenesis. In contrast, arsenic trioxide (As2O3) is an effective therapeutic agent for the treatment of acute promyelocytic leukemia, in which the binding of arsenite (iAsIII) to promyelocytic leukemia (PML) protein is the proposed initial step. These findings on the two-edged sword characteristics of arsenic suggest that after entry into cells, arsenic reaches the nucleus and triggers various nuclear events. Arsenic is reduced, conjugated with glutathione, and methylated in the cytosol. These biotransformations, including the production of reactive metabolic intermediates, appear to determine the intracellular dynamics, target organs, and biological functions of arsenic.

Promyelocytic leukemia (PML) nuclear bodies (PML-NBs), a class of membrane-less organelles in cells, are involved in multiple biological activities and are present throughout cells of adult organisms. Although the oocyte nucleus is an active region for the flux of multiple non-membranous organelles, PML-NBs have been predicted to be absent from oocytes. Here, we show that the deliberate assembly of PML-NBs during oocyte growth preferentially sequestered Small Ubiquitin-related Modifier (SUMO) protein from the nucleoplasm. SUMO not only was involved in the regulation of oocyte nuclear maturation but also was committed to the response, mediated by liquid droplet formation, to multiple stressors including nucleolar stress and proteotoxic stresses. Exogenous assembly of PML-NBs in the nucleus of oocytes affected the efficiency of the response of SUMO. These observations suggest that the PML-NB-free intranuclear milieu ensures that a reserve of SUMO remains available for emergent responses in oocyte development. This work demonstrated a benefit of the PML-NB-free intranuclear milieu, namely the ability to redirect the flux of SUMO otherwise needed to control PML-NB dynamics.

Secondary organic aerosol (SOA) is a component of airborne particulate matter in urban areas. However, their toxicities remain incompletely understood. In this study, we investigated the oxidative and inflammatory potency of SOA derived from three different volatile organic compounds (α-pinene, m-xylene, and trimethylbenzene) using human bronchial epithelial cells (BEAS-2B) and macrophages (U937). In BEAS-2B cells, all types of SOA extracts increased the expression of the heme oxygenase 1 (HMOX1) and interleukin-8 (IL8) genes, a typical marker for oxidative stress and inflammatory responses, respectively. Among the three types of SOA, m-xylene-derived SOA showed the strongest induction of the HMOX1 and IL8 genes, and transcriptional activity via the antioxidant response element (ARE). A causal candidate for SOA induction of oxidative stress is 2,6-dimethyl-1,4-benzoquinone (DMBQ) because only this quinone compound increased the transcriptional activity via ARE among components tested in this study. Similar to the case of BEAS-2B cells, SOA extracts increased the expression of HMOX1 and IL8 genes in U937 cells, mainly through oxidative stress, but these responses in U937 cells were prolonged when compared with BEAS-2B cells. Together, these results show that SOA affects lung epithelial cells and macrophages mainly through oxidative stress and inflammation, suggesting their contribution to the development of respiratory diseases.

Paraquat (PQ) is one of the commonly used herbicides in the world, despite its high toxicity. The ingestion of PQ accidentally or intentionally causes severe damage in diverse organs including the lung. Pulmonary fibrosis triggered by PQ accumulation in the lung epithelial cells is one of the major causes of death. This study investigated the intracellular accumulation of PQ, reactive oxygen species (ROS) generation and mitochondrial injury using two lung epithelial cell lines A549 and BEAS-2B (BEAS). Although A549 exhibit greater resistance to oxidative stress than BEAS, a cytotoxicity assay for PQ demonstrated that EC50 for lethality in A549 was 7 times lower than that in BEAS. When exposed to PQ at a concentration around EC50 for lethality, the amount of ROS generated in A549 was as low as that in BEAS. Conversely, the cellular concentration of PQ in A549 after exposure was higher than that in BEAS, which suggests a distinct difference in the susceptibility to PQ between these cell lines. After a 16 h exposure to PQ, mitochondrial membrane potential (MMP) decreased in A549, but decreased only slightly in BEAS even following a 30 h exposure. PQ-exposed A549 reduced an accumulation of PTEN-induced kinase 1 (PINK1), which works in degradation of damaged mitochondria, following the decrease of MMP, whereas PQ did not decline the PINK1 in BEAS. These results suggest that mitochondrial dysfunction due to cellular accumulation of PQ might contribute to the PQ-provoked toxicity more than the ROS generation in the lung epithelial cells.

Promyelocytic leukemia (PML) proteins are involved in the pathogenesis of acute promyelocytic leukemia (APL). Trivalent arsenic (As3+) is known to cure APL by binding to cysteine residues of PML and enhance the degradation of PML-retinoic acid receptor α (RARα), a t(15;17) gene translocation product in APL cells, and restore PML-nuclear bodies (NBs). The size, number, and shape of PML-NBs vary among cell types and during cell division. However, topological changes of PML-NBs in As3+-exposed cells have not been well-documented. We report that As3+-induced solubility shift underlies rapid SUMOylation of PML and late agglomeration of PML-NBs. Most PML-NBs were toroidal and granular dot-like in GFPPML-transduced CHO-K1 and HEK293 cells, respectively. Exposure to As3+ and antimony (Sb3+) greatly reduced the solubility of PML and enhanced SUMOylation within 2 h in the absence of changes in the number and size of PML-NBs. However, the prolonged exposure to As3+ and Sb3+ resulted in agglomeration of PML-NBs. Exposure to bismuth (Bi3+), another Group 15 element, did not induce any of these changes. ML792, a SUMO activation inhibitor, reduced the number of PML-NBs and increased the size of the NBs, but had little effect on the As3+-induced solubility change of PML. These results warrant the importance of As3+- or Sb3+-induced solubility shift of PML for the regulation intranuclear dynamics of PML-NBs.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication, poor social interactions, and repetitive behaviors. We aimed to examine autism-like behaviors and related gene expressions in rats exposed to diesel exhaust (DE)-origin secondary organic aerosol (DE-SOA) perinatally. Sprague&ndash, Dawley pregnant rats were exposed to clean air (control), DE, and DE-SOA in the exposure chamber from gestational day 14 to postnatal day 21. Behavioral phenotypes of ASD were investigated in 10~13-week-old offspring using a three-chambered social behavior test, social dominance tube test, and marble burying test. Prefrontal cortex was collected to examine molecular analyses including neurological and immunological markers and glutamate concentration, using RT-PCR and ELISA methods. DE-SOA-exposed male and female rats showed poor sociability and social novelty preference, socially dominant behavior, and increased repetitive behavior. Serotonin receptor (5-HT(5B)) and brain-derived neurotrophic factor (BDNF) mRNAs were downregulated whereas interleukin 1 &beta, (IL-&beta, ) and heme oxygenase 1 (HO-1) mRNAs were upregulated in the prefrontal cortex of male and female rats exposed to DE-SOA. Glutamate concentration was also increased significantly in DE-SOA-exposed male and female rats. Our results indicate that perinatal exposure to DE-SOA may induce autism-like behavior by modulating molecules such as neurological and immunological markers in rats.

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor class-A protein that is expressed on the cell surface of macrophages. MARCO mediates binding and ingestion of unopsonized environmental particles, including nano-sized materials. Exosomes are cell-derived, nano-sized vesicles (40–150 nm) that can contain lipids, RNA, DNA, and various proteins. Exosomes play an essential role in cell-to-cell communication via body fluids. However, mechanisms for the recognition and internalization of exosomes by recipient cells remain poorly characterized. In this study, cellular association of serum-derived fluorescent exosomes and 20-nm fluorescent nanoparticles (positive control) was compared between MARCO-expressing (CHO-MARCO) and control (CHO-CT) CHO-K1 cells to examine whether MARCO expression by recipient cells mediates the cellular uptake of exosomes and environmental nanoparticles. Fluorescence microscopic studies and quantitative analyses revealed that the cellular associations of both exosomes and 20-nm nanoparticles were greater in CHO-MARCO cells than in CHO-CT cells. Exosomes and nanoparticles colocalized with green fluorescent protein (GFP)-MARCO in cells transfected with GFP-MARCO-encoding constructs . Furthermore, inhibitory studies showed that actin reorganization and dynamin are involved in the MARCO-mediated cellular internalization of exosomes. These results indicated that MARCO plays a role in the uptake of exosomes.

Titania-supported palladium, gold and bimetallic nanoparticles (second-generation nanoparticles) demonstrate promising photocatalytic properties. However, due to unusual reactivity, second-generation nanoparticles can be hazardous for living organisms. Considering the ever-growing number of new types of nanoparticles that can potentially contaminate the environment, a determination of their toxicity is extremely important. The main aim of presented study was to investigate the cytotoxic effect of surface modified TiO2-based nanoparticles, to model their quantitative nanostructure–toxicity relationships and to reveal the toxicity mechanism. In this context, toxicity tests for surface-modified TiO2-based nanoparticles were performed in vitro, using Gram-negative bacteria Escherichia coli and Chinese hamster ovary (CHO-K1) cells. The obtained cytotoxicity data were analyzed by means of computational methods (quantitative structure–activity relationships, QSAR approach). Based on a combined experimental and computational approach, predictive models were developed, and relationships between cytotoxicity, size, and specific surface area (Brunauer–Emmett–Teller surface, BET) of nanoparticles were discussed.

Yoshika Kurokawa,1 Hideko Sone,1 Tin-Tin Win-Shwe,1 Yang Zeng,1 Hiroyuki Kimura,2 Yosuke Koyama,1 Yusuke Yagi,2 Yasuto Matsui,3 Masashi Yamazaki,4 Seishiro Hirano1 1Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, 2Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, 3Department of Environmental Engineering, Kyoto University Graduate School of Engineering, Kyoto, 4TIA Center Office, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan Abstract: Dendrimers have been expected as excellent nanodevices for brain medication. Anamine-terminated polyamidoamine dendrimer (PD), an unmodified plain type of PD, has the obvious disadvantage of cytotoxicity, but still serves as an attractive molecule because it easily adheres to the cell surface, facilitating easy cellular uptake. Single-photon emission computed tomographic imaging of a mouse following intravenous injection of a radiolabeled PD failed to reveal any signal in the intracranial region. Furthermore, examination of the permeability of PD particles across the blood–brain barrier (BBB) in vitro using a commercially available kit revealed poor permeability of the nanoparticles, which was suppressed by an inhibitor of caveolae-mediated endocytosis, but not by an inhibitor of macropinocytosis. Physicochemical analysis of the PD revealed that cationic PDs are likely to aggregate promptly upon mixing with body fluids and that this prompt aggregation is probably driven by non-Derjaguin–Landau–Verwey–Overbeek attractive forces originating from the surrounding divalent ions. Atomic force microscopy observation of a freshly cleaved mica plate soaked in dendrimer suspension (culture media) confirmed prompt aggregation. Our study revealed poor transfer of intravenously administered cationic PDs into the intracranial nervous tissue, and the results of our analysis suggested that this was largely attributable to the reduced BBB permeability arising from the propensity of the particles to promptly aggregate upon mixing with body fluids. Keywords: PAMAM dendrimer, nanomaterial, aggregation, blood–brain barrier

Autophagy molecules such as microtubule-associated protein light chain 3 (LC3) and p62/SQSTM1 have been used as biomarkers of protective or conversely adverse effects of exposure to toxicants. In the present study we show changes in LC3-II (a lipidated form of LC3-I) and p62 levels in response to zinc compounds and some other toxicants in J774.1 murine macrophages. The cytotoxicity of either ZnO or ZnSO4 largely depended on the concentration of FBS or albumin in the culture medium. Accordingly, these authophagy markers were more remarkably increased when the cells were exposed to ZnO or ZnSO4 in the absence of FBS. We next addressed lysosomal function impairment and changes in LC3-II and p62 levels following exposure to TiO2, ZnO, and ZnSO4. Lysosomal pH was quickly decreased by autolysosome inhibitors such as bafilomycin A1 and chloroquine, while TiO2, ZnO and ZnSO4 did not decrease lysosomal pH. However, the amounts of LC3-II and p62 and the LC3-II/LC3-I ratio were increased either by the lysosomal inhibitors and the Zn compounds. LC3-II and p62 levels were increased after exposure to arsenite and lipopolysaccharide (LPS). The p62 and phospho-p62 levels were also increased by either ZnSO4 and bafilomycin A1 in HEK293 cells stably expressing RFP-LC3. The current observations suggest that LC3-II and p62 levels were increased as consequences of early effects of toxicants without changing lysosomal pH.

Silver is commonly used as a disinfectant, and chronic exposure to silver may cause argyria, resulting in a gray–blue discoloration of human skin. However, the mechanism for cellular toxicity of silver has not been well explained. We studied the mode of cell death, the ratio of glutathione disulfide/glutathione, induction of metallothionein and activation of mitogen-activated protein kinases in J774.1 cells together with activation of antioxidant responsive element and nuclear factor-κB in CHO cells following exposure to silver ion (Ag+) to investigate the mechanism by which Ag+ causes lethal effects. Ag+ increased phosphorylation levels of extracellular signal-regulated, c-Jun N-terminal and p38 mitogen-activated protein kinases and remarkably increased the ratio of glutathione disulfide/glutathione in both a time- and concentration-dependent manner. Luciferase reporter gene assays revealed that antioxidant responsive element and nuclear factor-κB were activated following exposure to Ag+. In addition, exposure to Ag+ increased the mRNA and protein levels of metallothionein. We investigated whether or not Ag+ killed J774.1 cells by inducing apoptosis. Ag+ increased the activity of caspase-3/7 which was abrogated by caspase 3 and pan-caspase inhibitors. However, these inhibitors did not ameliorate the cytotoxic effects of Ag+, suggesting that Ag+ causes oxidative stress, which leads to necrotic rather than apoptotic cell death in J774.1 cells by decreasing functional sulfhydryl groups including glutathione in the cells. Copyright © 2016 John Wiley & Sons, Ltd.

Quaternary ammonium compounds (e.g., benzalkonium chloride (BAC) and cetylpyridinium chloride (CPC)) constitute a group of cationic surfactants are widely used for personal hygiene and medical care despite the potential pulmonary toxicity. To examine whether BAC and CPC aerosols deposited in the alveolar region alter pulmonary function, we studied the effects on pulmonary surfactant using two-step in vitro models; cytotoxicity using A549 alveolar epithelial cell and changes in surface activity of the pulmonary surfactant monolayer using both Surfacten® and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Cell viability was decreased with BAC and CPC dose-dependently. A comparison of cytotoxicity among BAC homologues with different length of alkyl chain showed that C16-BAC, which has the longest alkyl chain, was more cytotoxic than C12- or C14-BAC. Caspase-3/7 activity and cleaved form of caspase-3 and PARP were increased in BAC- and CPC-exposed cells. The elevated caspase-3/7 activity and their cleaved active forms were abolished by caspase-3-inhibitor. Furthermore, we examined the features of the surface pressure/trough area (π-A) isotherm by the Langmuir-Wilhelmy method and atomic force microscopy (AFM) images of lipid monolayers on a subphase containing BAC, CPC, or pyridinium chloride (PC, as a control). The π-A isotherms showed that addition of BAC or CPC yielded dose-dependent increases in surface pressure without compression, indicating that BAC and CPC expand the isotherm to larger areas at lower pressure. The collapse pressure diminished with increasing concentration of CPC. Topographic images indicated that BAC and CPC resulted in smaller condensed lipid domains compared to the control. Conversely, PC without hydrocarbon tail group, showed no cytotoxicity and did not change the isotherms and AFM images. These results indicate that BAC and CPC cause cell death via caspase-3-dependent apoptotic pathway in A549 cells and alter the alveolar surfactant activity. These effects can be attributed to the long alkyl chain of BAC and CPC.

Polyamidoamine (PAMAM) dendrimers have potential for biological applications as delivery systems for genes, drugs, and imaging agents into the brain, but their developmental neurotoxicity remains unknown. We investigated the effects of PAMAM dendrimers with various surface functional groups and multiple generations on neuronal differentiation using human neural progenitor cells at an equal mass concentration. Only PAMAM dendrimers containing amine (NH2) surface groups at concentrations of 10 μg/mL significantly reduced cell viability and neuronal differentiation, compared with non-amine-terminated dendrimers. PAMAM-NH2 with generation (G)3, G4, G5 G6, and G7 significantly decreased cell viability and inhibited neuronal differentiation from a concentration of 5 μg/mL, but G0, G1, and G2 dendrimers did not have any effect at this concentration. Cytotoxicity indices of PAMAM-NH2 dendrimers at 10 μg/mL correlated well with the zeta potentials of the particles. Surface group density and particle number in unit volume is more important characteristic than particle size to influence cytotoxicity for positive changed dendrimers. PAMAM-50% C12 at 1 μg/mL altered the expression level of the oxidative stress-related genes, ROR1, CYP26A1, and TGFB1, which is a DNA damage response gene. Our results indicate that PAMAM dendrimer exposure may have a surface charge-dependent adverse effect on neuronal differentiation, and that the effect may be associated with oxidative stress and DNA damage during development of neural cells.

Diphenylarsinic acid (DPAA) was detected as the primary compound responsible for the arsenic poisoning that occurred in Kamisu, Ibaraki, Japan, where people using water from a well that was contaminated with a high level of arsenic developed neurological (mostly cerebellar) symptoms and dysregulation of regional cerebral blood flow. To understand the underlying molecular mechanism of DPAA-induced cerebellar symptoms, we focused on astrocytes, which have a brain-protective function. Incubation with 10 µM DPAA for 96 h promoted cell proliferation, increased the expression of antioxidative stress proteins (heme oxygenase-1 and heat shock protein 70), and induced the release of cytokines (MCP-1, adrenomedullin, FGF2, CXCL1, and IL-6). Furthermore, DPAA overpoweringly increased the phosphorylation of three major mitogen-activated protein kinases (MAPKs) (ERK1/2, p38MAPK, and SAPK/JNK), which indicated MAPK activation, and subsequently induced expression and/or phosphorylation of transcription factors (Nrf2, CREB, c-Jun, and c-Fos) in cultured rat cerebellar astrocytes. Structure-activity relationship analyses of DPAA and other related pentavalent organic arsenicals revealed that DPAA at 10 µM activated astrocytes most effective among organic arsenicals tested at the same dose. These results suggest that in a cerebellum exposed to DPAA, abnormal activation of the MAPK-transcription factor pathway and irregular secretion of these neuroactive, glioactive, and/or vasoactive cytokines in astrocytes can be the direct/indirect cause of functional abnormalities in surrounding neurons, glial cells, and vascular cells: This in turn might lead to the onset of cerebellar symptoms and disruption of cerebral blood flow.

Asbestos and silica (exogenous danger) and adenosine triphosphate (ATP, endogenous danger-signaling molecule) synergistically increase IL-1β release from endotoxin-primed macrophage, which is mediated by NOD-like receptor protein 3 (NLRP3) inflammasome. However, the conversion of pro-IL-1β to its active form seems to depend on the macrophage cell types. In the present study, bone marrow-derived macrophages (BMM) and three murine macrophage cell lines, J774.1, J774A.1, and RAW264.7 were exposed to ATP or fibrous titanium dioxide (FTiO2) in the presence or absence of lipopolysaccharide (LPS), and the concentrations of IL-1β and IL-6 in both cell lysates and in the culture media were measured by immunoblotting to differentiate active form of IL-1β from pro-IL-1β. IL-1β release was synergistically increased when the cells were exposed to both LPS and ATP or FTiO2, while IL-6 was readily released by LPS alone. IL-1β released into the culture medium was pro-IL-1β in J774.1 and RAW264.7, and most of the pro-IL-1β remained inside the cells. In contrast, the active form of IL-1β was released together with pro-IL-1β from J774A.1 and BMM after the co-stimulation. J774A.1 and BMM express apoptosis-associated speck-like protein contains a carboxyl-terminal CARD (ASC) while J774.1 and RAW264.7 do not or only faintly express ASC, and accordingly, caspase-1, which converts pro-IL-1β to its active form, is activated only in J774A.1 and BMM. Collectively, the canonical inflammasome pathway is not activated in J774.1 and RAW264.7, and the apparent synergistical increase of IL-1β in the culture medium mostly reflects the leakage of pro-IL-1β from these cells.

Exposure to ambient air pollutants has been reported to have various adverse health impacts. Ambient particulate matter comprises primary particles released directly via engine exhaust and secondary organic aerosols (SOAs) formed from oxidative reactions of the ultrafine particle fraction of diesel exhaust (DE). Toll-like receptor 4 (TLR4) is well known to initiate the inflammatory cascade in the central nervous system. However, whether and how DE and DE-SOA exposure influences TLR4 signaling in the immature brain remains unclear. We attempted to evaluate the roles of TLR-4, inflammatory mediators and microglial markers in the impaired spatial learning ability of neonatal mice exposed to DE and DE-SOAs. Pregnant C3H/HeN (TLR4-intact) and C3H/HeJ (TLR4- mutated) mice were exposed to clean air, DE or DE-SOA from gestational day 14 to postnatal day (PND) 10 (5 h/day for 5 days) in exposure chambers. PND11 neonatal mice were examined for their performance in the olfactory-based spatial learning test. After the spatial learning test, the hippocampi of the mice were removed and real-time RT-PCR analysis was performed to examine the neurological and immunological markers. Both male and female C3H/HeN and C3H/HeJ neonatal mice exposed to DE and DE-SOAs showed poor performance in the test phase of spatial learning as compared to the mice exposed to clean air. However, this spatial learning deficit was prominent in C3H/HeJ neonatal mice. In the neonatal C3H/HeN male mice exposed to DE and DE-SOAs, the mRNA expression levels of the NMDA receptor subunits (NR1, NR2B), proinflammatory cytokines, tumor necrosis factor-α and cyclooxygenase-2, oxidative stress marker, heme oxygenase-1, and microglial marker, Iba1, in the hippocampus were significantly increased, but these changes were not observed in female mice. Our findings indicate that activation of the neuroimmune system and TLR4 signaling may possibly be involved in environmental pollutant-induced spatial learning impairment in neonatal mice.

Inorganic arsenite (iAs(3+)) is a two-edged sword. iAs(3+) is a well-known human carcinogen; nevertheless, it has been used as a therapeutic drug for acute promyelocytic leukemia (APL), which is caused by a fusion protein comprising retinoic acid receptor-α and promyelocytic leukemia (PML). PML, a nuclear transcription factor, has a RING finger domain with densely positioned cysteine residues. To examine PML-modulated cellular responses to iAs(3+), CHO-K1 and HEK293 cells were each used to establish cell lines that expressed ectopic human PML. Overexpression of PML increased susceptibility to iAs(3+) in CHO-K1 cells, but not in HEK293 cells. Exposure of PML-transfected cells to iAs(3+) caused PML to change from a soluble form to less soluble forms, and this modification of PML was observable even with just 0.1 μM iAs(3+) (7.5 ppb). Western blot and immunofluorescent microscopic analyses revealed that the biochemical changes of PML were caused at least in part by conjugation with small ubiquitin-like modifier proteins (SUMOylation). A luciferase reporter gene was used to investigate whether modification of PML was caused by oxidative stress or activation of antioxidant response element (ARE) in CHO-K1 cells. Modification of PML protein occurred faster than activation of the ARE in response to iAs(3+), suggesting that PML was not modified as a consequence of oxidative stress-induced ARE activation.

In Japan, people using water from the well contaminated with high-level arsenic developed neurological, mostly cerebellar, symptoms, where diphenylarsinic acid (DPAA) was a major compound. Here, we investigated the adverse effects of developmental exposure to 20mg/l DPAA in drinking water (early period [0-6 weeks of age] and/or late period [7-12]) on behavior and cerebellar development in male rats. In the open field test at 6 weeks of age, early exposure to DPAA significantly increased exploratory behaviors. At 12 weeks of age, late exposure to DPAA similarly increased exploratory behavior independent of the early exposure although a 6-week recovery from DPAA could reverse that change. In the passive avoidance test at 6 weeks of age, early exposure to DPAA significantly decreased the avoidance performance. Even at 12 weeks of age, early exposure to DPAA significantly decreased the test performance, which was independent of the late exposure to DPAA. These results suggest that the DPAA-induced increase in exploratory behavior is transient, whereas the DPAA-induced impairment of passive avoidance is long lasting. At 6 weeks of age, early exposure to DPAA significantly reduced the concentration of cerebellar total glutathione. At 12 weeks of age, late, but not early, exposure to DPAA also significantly reduced the concentration of cerebellar glutathione, which might be a primary cause of oxidative stress. Early exposure to DPAA induced late-onset suppressed expression of NMDAR1 and PSD95 protein at 12 weeks of age, indicating impaired glutamatergic system in the cerebellum of rats developmentally exposed to DPAA.

It has been demonstrated that exposure to diesel exhaust (DE) is associated with the induction and exacerbation of respiratory disorders; however, the impacts of DE containing mainly nanoparticles have been less studied. We have previously demonstrated that inhalation exposure to nanoparticle-rich DE (NR-DE) exacerbated allergic pulmonary inflammation, in the context of enhanced local expression of proinflammatory molecules. However, the underlying mechanisms have not been fully elucidated. 8-Hydroxydeoxyguanosine (8-OHdG) is a marker of oxidative damage, particularly in DNA. This study examined the effects of NR-DE on 8-OHdG synthesis in the lung in the presence or absence of an allergen. Institute for Cancer Research (ICR) mice were exposed by inhalation to four different gas compositions (control air, low-concentration DE, high-concentration DE and high-concentration DE without particulate matter) for 8 weeks, in the presence or absence of repetitive intratracheal administration of ovalbumin (OVA). Thereafter, we assessed the levels of 8-OHdG synthesis and expression in the lungs by means of enzyme immunoassay (EIA) and immunohistochemistry. The EIA revealed that the level of 8-OHdG was significantly higher in the high-concentration NR-DE-exposed and allergen-sensitized/stimulated group compared with that in the control air-exposed and allergen-treated group. The immunohistochemistry results demonstrated that the level of immunoreactive 8-OHdG was higher in the NR-DE-exposed and allergen-treated lungs compared with that in the corresponding control air-exposed lungs. The results suggested that NR-DE exposure enhanced 8-OHdG formation in asthmatic lungs. This, at least in part, is involved in the NR-DE-mediated exacerbation of the allergic pathophysiology that was identified in our previous study.

Recently, we have reported that primary particles from diesel exhaust affect nervous system, immune system, and learning ability in mice. Currently, in vivo and in vitro studies have shown that secondary organic aerosol (SOA) generated from the coal-fired power plant induced adverse effects in lung and heart. However, the effect of SOA on central nervous system is still unknown. In the present study, using potential biomarkers recognized in previous studies of primary particles, we investigated the effect of acute single administration of SOA on the expression levels of various biomarkers in the brain and lung of mice. We generated the SOA by addition of ozone (O(3)) to the diesel exhaust particle (DEP). Eight-week-old male BALB/c mice were administered DEP or DEP+O(3) (SOA) (50 µg/50 µl/mouse) intranasally. Twenty-four hour after acute single exposure to SOA, olfactory bulb, hippocampus and lung from all mice were collected and mRNA expressions of neurological and immunological biomarkers were examined using real-time RT-PCR analysis and histological examination. Proinflammatory cytokines, their transcription factor and neurotrophin mRNA were remarkably increased in lung of mice exposed to SOA but not in the brain. Microarray data showed that changes of the inflammatory reaction and metabolizing enzyme gene cluster were observed in the brain and lung. Our findings suggested that an acute single exposure of SOA does not affect biomarkers in the brain of normal healthy individuals. Our present results also clearly indicate that SOA induces inflammatory responses in the lung by modulating proinflammatory cytokines, transcription factor and inflammatory responsive neurotrophins.

Exposure to asbestos is a risk for malignant mesothelioma (MM) in humans. Among the commercially used types of asbestos (chrysotile, crocidolite, and amosite), the carcinogenicity of chrysotile is not fully appreciated. Here, we show that all three asbestos types similarly induced MM in the rat peritoneal cavity and that chrysotile caused the earliest mesothelioma development with a high fraction of sarcomatoid histology. The pathogenesis of chrysotile-induced mesothelial carcinogenesis was closely associated with iron overload: repeated administration of an iron chelator, nitrilotriacetic acid, which promotes the Fenton reaction, significantly reduced the period required for carcinogenesis; massive iron deposition was found in the peritoneal organs with high serum ferritin; and homozygous deletion of the CDKN2A/2B/ARF tumour suppressor genes, the most frequent genomic alteration in human MM and in iron-induced rodent carcinogenesis, was observed in 92.6% of the cases studied with array-based comparative genomic hybridization. The induced rat MM cells revealed high expression of mesoderm-specific transcription factors, Dlx5 and Hand1, and showed an iron regulatory profile of active iron uptake and utilization. These data indicate that chrysotile is a strong carcinogen when exposed to mesothelia, acting through the induction of local iron overload. Therefore, an intervention to remove local excess iron might be a strategy to prevent MM after asbestos exposure. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Recently, our laboratory reported that exposure to nanoparticle-rich diesel exhaust (NRDE) for 3 months impaired hippocampus-dependent spatial learning ability and up-regulated the expressions of memory function-related genes in the hippocampus of female mice. However, whether NRDE affects the hippocampus-dependent non-spatial learning ability and the mechanism of NRDE-induced neurotoxicity was unknown. Female BALB/c mice were exposed to clean air, middle-dose NRDE (M-NRDE, 47 μg/m(3)), high-dose NRDE (H-NRDE, 129 μg/m(3)), or filtered H-NRDE (F-DE) for 3 months. We then investigated the effect of NRDE exposure on non-spatial learning ability and the expression of genes related to glutamate neurotransmission using a novel object recognition test and a real-time RT-PCR analysis, respectively. We also examined microglia marker Iba1 immunoreactivity in the hippocampus using immunohistochemical analyses. Mice exposed to H-NRDE or F-DE could not discriminate between familiar and novel objects. The control and M-NRDE-exposed groups showed a significantly increased discrimination index, compared to the H-NRDE-exposed group. Although no significant changes in the expression levels of the NMDA receptor subunits were observed, the expression of glutamate transporter EAAT4 was decreased and that of glutamic acid decarboxylase GAD65 was increased in the hippocampus of H-NRDE-exposed mice, compared with the expression levels in control mice. We also found that microglia activation was prominent in the hippocampal area of the H-NRDE-exposed mice, compared with the other groups. These results indicated that exposure to NRDE for 3 months impaired the novel object recognition ability. The present study suggests that genes related to glutamate metabolism may be involved in the NRDE-induced neurotoxicity observed in the present mouse model.

An incident of poisoning occurred in Japan in 2003 when high-level contamination with arsenic, mainly diphenylarsinic acid (DPAA), was found in well water. People using this water particularly experienced cerebellar symptoms. In the present study, we investigated the adverse effects of DPAA on the cerebellum in vitro and in vivo to understand the biological mechanisms that cause cerebellar symptoms. Comprehensive gene expression analyses in primary cultured ratcerebellar cells exposed to 10 μM DPAA for 24 hours indicated significant alterations in the mRNA expression of genes encoding antioxidative stress proteins (heme oxigenase 1 and heat shock protein72) and neuroactive and vasoactive peptides (neuropeptide Y, adrenomedullin, monocyte chemoattractant protein 1, and fibroblast growth factor 2). Further analyses of proteins revealed that cultured cerebellar astrocytes expressed these antioxidative stress proteins and peptides in response to exposure to DPAA. In addition, these adverseeffects were also observed in the cerebellum exposed in vivo to DPAA (100 mg/L) for 21 days. These results suggested that cerebellarastrocytes irregularly secrete neuroactive and vasoactive peptidesagainst DPAA-induced oxidative stress, which leads to abnormal neural functions and disrupted cerebellar autoregulation dynamics and results in the onset of cerebellar symptoms.

Among the symposia organized by various study groups in the Japanese Society of Hygiene (JSH), the Study Group on Fibrous and Particulate Substances (SGFPS) presented a symposium entitled "The frontline of nanoparticle research" chaired by Professor Takemi Otsuki (Kawasaki Medical School, Japan) and Dr. Seishiro Hirano (National Institute for Environmental Studies, Japan) on 26 March, 2012, as a part of the program of the 82nd Annual Meeting of JSH in Kyoto, Japan. Special features consist of three presentations given at the above-mentioned symposium. In this article, we introduce the progress of the Study Group on Fibrous and Particulate Substances (SGFPS) from the initial symposium entitled "Asbestos: Science and Society" held at the 76th Annual Meeting of JSH at Ube, Japan to the last above-mentioned symposium in Kyoto. The health-related issues caused by exposure to fibrous materials such as asbestos and also particulated substances such as nanoparticles will be lasting in the future and researchers including our study group have to make their best efforts to resolve these problems and to reduce health impairments due to exposure to environmental fibrous and particulated substances.

In the present study, in order to reveal novel adverse effects of ultrafine particles (UFP) on the central nervous system, the effects of nanoparticle-rich diesel exhaust particles (NRDEP; count mode diameter, 21.45 nm) on emotional behavior, learning capability and brain neurotransmitter levels were studied in rats by intranasal instillation (iNI). NRDEP (10 and 50 µg/rat) was instilled into 2-week old infant, male rats once a week for 4 weeks. Spontaneous motor activity measured was observed to be inverse to the dose level. In active avoidance tests using a shuttle box, NRDEP-treated animals showed a lower avoidance performance than control animals given air-instillation. The levels of dopamine and its metabolite (DOPAC) in the medial mammillary nucleus of the brain tended to be lower in the NRDEP-treated animals. From these results, although the effects of NRDEP by iNI on the emotionality and the brain neurotransmitter levels were not fully clear, the results obtained by avoidance testing suggested involvement of UFP in learning capability.

A high-performance liquid chromatography (HPLC) method has been developed for the assays of five barbiturates in human urine using a new thermoresponsive polymer separation column, which is composed of N-isopropylacrylamide polymer. According to elevating the column temperature from 10 ℃ to 50 ℃, five barbiturates, such as metharbital, primidone, phenobarbital, mephobarbital and pentobarbital, became well separated by this method. Five barbiturates showed good linearity in the range of 0.2-10 mg/ml. Good accuracy, precision and recoveries for these drugs were obtained at 1 and 5 μg/ml urine. The method with the new-type column seems to have high potential to be extensively used in forensic toxicology for analysis of many drugs and poisons by HPLC and HPLC-mass spectrometry (MS) (-MS).

The development of nanotechnology has increased the risk of exposure to types of particles other than combustion-derived particles in the environment, namely, industrial nanomaterials. On the other hand, patients with bronchial asthma are sensitive to inhaled substances including particulate matters. This study examined the effects of pulmonary exposure to a type of nano-sized carbon nanotube (multi-walled nanotubes: MWCNT) on allergic airway inflammation in vivo and their cellular mechanisms in vitro. In vivo, ICR mice were divided into 4 experimental groups. Vehicle, MWCNT (50 microg/animal), ovalbumin (OVA), and OVA+MWCNT were repeatedly administered intratracheally. Bronchoalveolar lavage (BAL) cellularity, lung histology, levels of cytokines related to allergic inflammation in lung homogenates/BAL fluids (BALFs), and serum immunoglobulin levels were studied. Also, we evaluated the impact of MWCNT (0.1-1 microg/ml) on the phenotype and function of bone marrow-derived dendritic cells (DC) in vitro. MWCNT aggravated allergen-induced airway inflammation characterized by the infiltration of eosinophils, neutrophils, and mononuclear cells in the lung, and an increase in the number of goblet cells in the bronchial epithelium. MWCNT with allergen amplified lung protein levels of Th cytokines and chemokines compared with allergen alone. MWCNT exhibited adjuvant activity for allergen-specific IgG(1) and IgE. MWCNT significantly increased allergen (OVA)-specific syngeneic T-cell proliferation, particularly at a lower concentration in vitro. Taken together, MWCNT can exacerbate murine allergic airway inflammation, at least partly, via the promotion of a Th-dominant milieu. In addition, the exacerbation may be partly through the inappropriate activation of antigen-presenting cells including DC.

Diesel exhaust particles are a major constituent of ambient particulate matter, and most particles emitted directly from diesel exhaust are smaller than 1microm in diameter. Recently, the toxicity of diesel engine-derived nanoparticles has come to be recognized as an emerging social issue. In the present study, we investigated spatial learning ability and memory function-related gene expressions in mouse hippocampus after the exposure of animals to nanoparticle-rich diesel exhaust (NRDE) with or without a bacterial cell wall component. Lipoteichoic acid (LTA), a cell wall component derived from Staphylococcus aureus, was used to induce systemic inflammation. Male BALB/c mice were exposed to clean air (particle concentration, 4.58microg/m(3)) or NRDE (148.86microg/m(3)) for 5h per day on 5 days of the week for 4 weeks in an exposure chamber, with or without the weekly intraperitoneal injection of LTA. On the day after the final day of exposure, we used a Morris water maze apparatus to examine the ability of the animals to perform a spatial learning task. After the completion of the test, the animals were sacrificed and the hippocampus was collected from each mouse; the expressions of NMDA receptor subunits (NR1, NR2A and NR2B), proinflammatory cytokines (IL-1beta and TNF-alpha) and the oxidative stress marker heme oxygenase 1 were then investigated using real-time RT-PCR. In the Morris water maze task, NRDE/LTA (+) group took a longer time to reach the hidden platform than clear air/LTA (-) group. However, NRDE exposure alone did not affect it. The relative mRNA levels of the NMDA receptor subunits and proinflammatory cytokines were higher in hippocampus of NRDE/LTA (+) group compared to clear air/LTA (-) group. These results indicate that co-exposure of NRDE and LTA could affect spatial learning and memory function-related gene expressions in mouse hippocampus.

Translocation of inhaled ultrafine particles from the lungs into the blood may impair cardiovascular function. We administered ultrafine (20-nm) and fine (200-nm) gold colloid or fluorescein-labeled polystyrene particles to mice intratracheally and examined their localization in the lung and extrapulmonary organs. Fifteen minutes after instillation, dispersed and agglomerated 20-nm gold colloid particles were observed on the surface of endothelial cells, on the alveolar surface, in endocytotic vesicles of alveolar epithelial cells, and in the basement membrane of the lung. A small but noteworthy amount of gold was detected in the liver, kidney, spleen, and heart by inductively coupled plasma-mass spectrometry. After administration of 20- or 200-nm fluorescent particles, free particles were detected infrequently in blood vessels, on the endocardial surface, and in the kidney and liver only in the mice that received 20-nm particles, whereas phagocytes containing 20- or 200-nm particles were found in the extrapulmonary tissues. Fluorescent particle-laden alveolar macrophages administered intratracheally translocated from alveoli to extrapulmonary organs via the blood circulation. Thus, small amounts of ultrafine particles are transported across the alveolar wall into the blood circulation via endocytotic pathways, but particle-laden alveolar macrophages translocate both ultrafine and fine particles from the lungs to the extrapulmonary organs.

Secondary organic aerosol (SOA) is a component of particulate matter (PM) 2.5 and formed in the atmosphere by oxidation of volatile organic compounds. Recently, we have reported that inhalation exposure to diesel engine exhaust (DE) originated SOA (DE-SOA) affect novel object recognition ability and impair maternal behavior in adult mice. However, it is not clear whether early life exposure to SOA during the de-velopmental stages affect social behavior in adult life or not. In the present study, to investigate the effects of early life exposure to DE-SOA during the gestational and lactation stages on the social behavior in the adult life, BALB/c mice were exposed to clean air (control), DE, DE-SOA and gas without any particulate matter in the inhala-tion chambers from gestational day 14 to postnatal day 21 for 5 h a day and 5 days per week. Then adult mice were examined for changes in their social behavior at the age of 13 week by a sociability and social novelty preference, social interaction with a juvenile mouse and light-dark transition test, hypothalamic mRNA expression levels of social behavior-related genes, estrogen receptor-alpha and oxytocin receptor as well as of the oxidative stress marker gene, heme oxygenase (HO)-1 by real-time RT-PCR method. In addition, hypothalamic level of neuronal excitatory marker, glutamate was determined by ELISA method. We observed that sociability and social novelty pref-erence as well as social interaction were remarkably impaired, expression levels of es-trogen receptor-alpha, oxytocin receptor mRNAs were significantly decreased, ex-pression levels of HO-1 mRNAs and glutamate levels were significantly increased in adult male mice exposed to DE-SOA compared to the control ones. Findings of this study indicate early life exposure of BALB/c mice to DE-SOA may affect their late-onset hypothalamic expression of social behavior related genes, trigger neurotoxi-city and impair social behavior in the males.

The health effects of silver nanoparticles (AgNPs) have not been well investigated, despite AgNPs now being widely used in consumer products. We introduce living environment, analysis, metabolic behavior, toxicity, and human health effect of AgNPs in comparison to silver nitrate (AgNO3). The American Conference of Governmental Industrial Hygienists (ACGIH) has established separate threshold limit values (TLV) for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). Argyria and argyrosis are chronic disorders of skin microvessels and eyes in humans, and these disorders reportedly develop following extended oral and inhalational exposure to Ag. In mammals, AgNO3 and AgNPs increased the number of the total cells, neutrophils, and pro-inflammatory cytokine production “IL-1β,” and these were distributed in the lung, kidney, and liver. The amount of Ag in the metallothionein (MT)-bound form was related in cellular behavior and toxicity of AgNPs and AgNO3. The cytotoxic effect of AgNPs is a simple function of neither the number nor total surface area. Although the effect may vary among the cell types and the culture conditions, AgNPs were transported to lysosomes and only gradually dissolved in mammals, causing milder inflammatory stimulation.

The tissue distribution and chemical forms of arsenic were compared in two animal species with different metabolic capacity and toxicity to arsenic. Hamsters and rats were given a single oral dose of arsenite (iAsIII) at 5.0 mg As/kg body weight, and then the concentrations of arsenic were determined; more than 75% of the dose accumulated in rat red blood cells (RBCs) in the form of dimethylarsinous acid (DMAIII), whereas less than 0.8% of the dose accumulated in hamster RBCs, mostly in the form of monomethylarsonous acid (MMAIII). Reflecting the low accumulation in RBCs, more than 63% of the dose was recovered in hamster urine within one week (7.8-fold higher than that in rat urine). The quantity of arsenic distributed in the liver and kidneys was significantly higher in hamsters than in rats, and arsenic in livers stayed much longer in hamsters than in rats. Arsenic accumulated more and was retained longer in the kidneys than in the livers in both animals, and in hamster kidneys, it accumulated at levels higher than those in rat kidneys in the form of MMAIII bound to proteins. In the first 24 h urine, dimethylmonothioarsinic (DMMTAV) and dimethyldithioarsinic (DMDTAV) acids were detected in hamsters, but only DMMTAV was found in rats, together with an unknown arsenic metabolite in both animals. The unknown urinary arsenic metabolite was identified as monomethylmonothioarsonic acid (MMMTAV; CH3As(=S)(OH)2). The present results indicate that in hamsters, arsenic does not accumulate in RBCs, and therefore, hamsters exhibit a more uniform tissue distribution and faster urinary excretion of arsenic than rats. In addition, arsenic was thiolated more in hamsters than in rats excreting mono and dimethylated thioarsenicals in urine.

Although several studies have demonstrated that airway exposure to diesel exhaust particles (DEP) induces lung inflammation, the signaling pathways involved in the pathogenesis remain unclear. Toll-like receptors (TLRs) are generally accepted to be pathogen recognition receptors in mammalians. In the present study, we investigated the role of TLR-4 in DEP-induced lung inflammation and cytokine expression in the lung in TLR-4 point mutant (C3H/HeJ) mice and corresponding control (C3H/HeN) mice. Both the types of mice were randomized into four experimental groups that received vehicle or DEP (12 mg/kg body weight) by intratracheal instillation (n = 8-10 in each group). Cellular profile of bronchoalveolar lavage (BAL) fluid, expressions of cytokines and chemokines in the lung, and circulatory fibrinogen levels were evaluated 24 h after the instillation.DEP challenge revealed a significant increase in the numbers of total cells and neutrophils in the BAL fluid as compared to vehicle challenge, however, the numbers were less in C3H/HeJ mice than in C3H/HeN mice. DEP exposure significantly induced the lung expression of interleukin (IL)-1beta, keratinocyte chemoattractant (KC), and macrophage inflammatory protein (MIP)-1alpha when compared to vehicle challenge in both genotypes of mice. In the presence of DEP, the level of MIP-1alpha was significantly lower in C3H/HeJ mice than in C3H/HeN mice, however, the levels of IL-1beta, KC, and fibrinogen showed opposite findings. These results suggest that TLR-4 is one of recognition receptors against DEP in the airways.

Diesel exhaust particles (DEP) induce pulmonary diseases including asthma and chronic bronchitis. Comprehensive evaluation is required to know the mechanisms underlying the effects of air pollutants including DEP on lung diseases. Using a cDNA microarray, we examined changes in gene expression in SV40T2 cells, a rat alveolar type II epithelial cell line, following exposure to an organic extract of DEP. We identified candidate sensitive genes that were up- or down-regulated in response to DEP. The cDNA microarray analysis revealed that a 6-h exposure to the DEP extract (30 microg/ml) increased (2-fold) the expression of 51 genes associated with drug metabolism, antioxidation, cell cycle/proliferation/apoptosis, coagulation/fibrinolysis, and expressed sequence tags (ESTs), and decreased (0.5-fold) that of 20 genes. In the present study, heme oxygenase (HO)-1, an antioxidative enzyme, showed the maximum increase in gene expression; and type II transglutaminase (TGM-2), a regulator of coagulation, showed the most prominent decrease among the genes. We confirmed the change in the HO-1 protein level by Western blot analysis and that in the enzyme activity of TGM-2. The organic extract of DEP increased the expression of HO-1 protein and decreased the enzyme activity of TGM-2. Furthermore, these effects of DEP on either HO-1 or TGM-2 were reduced by N-acetyl-l-cysteine (NAC), thus suggesting that oxidative stress caused by this organic fraction of DEP may have induced these cellular responses. Therefore, an increase in HO-1 and a decrease in TGM-2 might be good markers of the biological response to organic compounds of airborne particulate substances.

Although inorganic arsenate (iAsV) and arsenite (iAsIII) are metabolized in liver and excreted into bile and urine, the metabolites in the bile after the oral intake of iAs remain unclear. Male Sprague-Dawley rats were orally (po) or intravenously (iv) exposed to iAs and methylated arsenics, and the arsenic speciation in the urine and bile was analyzed by high performance liquid chromatography-inductively coupled argon plasma mass spectrometry. Arsenic caused induction of multidrug resistance-associated protein 2 (MRP2), and changes of glutathione (GSH) levels in the liver and bile were also determined. The metabolic speciation studies revealed that arsenic was excreted into bile in the methylarsenic-diglutathione (MADG) and/or dimethylarsenic acid (DMAV) forms in iAsIII- or iAsV-po rats, but that MADG and arsenic-triglutathione (ATG) are the main forms excreted into bile both in iAsIII- and iAsV-iv rats. In MADG-po rats, the MADG was excreted into bile in the MADG and DMAV forms. Monomethylarsonic acid (MMAV)- and DMAV-iv rats did not excrete significant amounts of either MMAV or DMAV into bile and mostly excreted into urine in the unchanged chemical forms. Taken together, the DMAV detected in the bile is mostly supposed to be the dissociation of dimethylarsenic-glutathione (DMAG). Urinary arsenic speciation showed that arsenic metabolized to 43% methylated DMAV, 47% unmethylated iAsIII, and 10% iAsV in iAsIII-iv rats, whereas only 3% methylated DMAV, 87% unmethylated iAsV, and 10% iAsIII were detected in iAsV-iv rats. Arsenic was accumulated dose dependently, and arsenic concentration was significantly higher in the iAsIII-po rat liver than in the iAsV-po rat liver. GSH levels in the bile were decreased by relatively higher doses of iAsV-po, but significantly increased by iAsIII- or iAsV-iv. iAs-exposure increased the expression of MRP2 in the liver. Pretreatment with buthionine sulfoximine predominantly inhibited arsenic excretion into bile in iAs-iv rats. In conclusion, our data demonstrated that biliary and urinary arsenic excretion and speciation are affected by the route, dose, and chemical forms of arsenical administration, and GSH plays a key role in arsenic metabolism. We are also first to show that DMAV that probably originated from DMAG is excreted into the bile in iAs-po rats.

This study aimed to identify potential abnormalities of retinoblastoma protein (pRb) and p16(INK4a) (p16) expression in resectable colorectal carcinomas (CRCs) and to assess the prognostic significance of pRb and p16 levels in patients with CRC. From July 1990 through December 1993, 117 consecutive patients with CRC underwent curative resection with radical lymphadenectomy. The resected specimens were examined immunohistochemically using monoclonal antibodies to identify abnormalities of pRb and p16 expression. The association of pRb and p16 expression status with clinicopathologic features was analyzed retrospectively. The Cox proportional hazards model was used to identify factors independently affecting survival after resection. The median follow-up period was 62 months. Aberrant expression of pRb and p16 was identified in 82 (70%) and 87 (74%) patients, respectively. Coincident abnormalities of these proteins occurred in 61 (52%) patients. Loss of pRb expression correlated with tumor site (P = 0.0119), whereas p16 overexpression correlated with tumor size (P = 0.0034). Coincident abnormalities of pRb and p16 were associated with TNM tumor stage (P = 0.011). The outcome after resection was worse in patients with aberrant expression of pRb and/or p16 than in patients with normally expressed pRb and p16 (for pRb, P = 0.0151; for p16, P = 0.0247). Coincident abnormalities of pRb and p16 indicated the worst patient survival (P = 0.0310). Aberrant expression of pRb and p16 independently affected postresection survival (relative risk = 6.312, P

Intake of inorganic arsenic is known to cause vascular diseases as well as skin lesions and cancer in humans. We investigated the differences in cytotoxicity, uptake rate of arsenic, and gene expression of antioxidative enzymes between arsenite (As(3+))- and arsenate (As(5+))-exposed rat heart microvessel endothelial cells. As(3+) was more cytotoxic than As(5+), and LC(50) values were calculated to be 36 and 220 micro M, respectively. As(3+) (1-25 micro M) increased mRNA levels of antioxidant enzymes such as heme oxygenase-1 (HO-1), thioredoxin peroxidase 2, NADPH dehydrogenase, and glutathione S-transferase P subunit. HO-1 mRNA levels showed the most remarkable increase in response to As(3+). cDNA microarray analysis indicated that there was no prominent difference in arsenic-induced transcriptional changes between As(3+)- and As(5+)-exposed cells, when the cells were exposed to one-fourth the LC(50) concentration of arsenic (9 and 55 micro M for As(3+) and As(5+), respectively). N-acetyl- l-cysteine (NAC) reduced both the cytotoxicity of inorganic arsenic and the HO-1 mRNA level, and buthionine sulfoximine enhanced cytotoxicity of inorganic arsenic. As(3+) was taken up by the endothelial cells 6-7 times faster than As(5+), and the presence of NAC in the culture medium did not change the uptake rate of As(3+). These results suggest that the effects of NAC on arsenic-induced cytotoxicity and oxidative stress were due to the antioxidative role of non-protein thiols and not to chelation of arsenic in the culture medium. The difference in cellular uptake of arsenic between As(3+) and As(5+) appeared not to be due to the ionic charge on arsenic (at physiological pH, trivalent arsenic is neutral whereas pentavalent arsenic is negatively charged). These results suggest that the higher toxicity of As(3+) compared with that of As(5+) is probably due to the faster uptake of As(3+) by endothelial cells, and inorganic arsenic exerts its toxicity at least in part via intracellular oxidative stress.

The extent of exposure of residents of Changqing (Guizhou, PR China) to arsenic through coal-burning was investigated. Despite the low coal-arsenic content (56.3+/-42.5 mg As kg(-1)) when compared with coals collected at different location and times from the same province, more than 30% of the study subjects have shown symptoms of arsenicosis. Coal, urine, hair, and water samples were collected in mid-September 2001 and analysed for arsenic. The average urinary and hair-arsenic concentrations in the exposed subjects were 71.4+/-37.1 microg As g(-1) creatinine (control 41.6+/-12.1) and 7.99+/-8.16 mg kg(-1), respectively. A positive correlation between the hair and urinary-arsenic concentration (R(2)=0.601) was found. There was no significant difference between females and males for both urinary and hair-arsenic concentrations. Females were found to have a higher dimethylarsinic acid but lower percentages of inorganic arsenic and monomethylarsonic acid in their urine than males.

Background Previous studies have shown that lipopolysaccharide-induced inflammation in the lung results in tyrosine nitration. The objective of this study was to evaluate the contribution of myeloperoxidase and peroxynitrite pathway to the tyrosine nitration in lipopolysaccharide-administered lungs of rats that were otherwise untreated or leukocyte-depleted by cyclophosphamide or received inhaled nitric oxide (NO). Methods The authors analyzed the immunoreactivity of inducible nitric oxide synthase (iNOS), nitrotyrosine (a product of the myeloperoxidase or peroxynitrite pathway), and chlorotyrosine (a byproduct of the myeloperoxidase pathway) by use of specific antibodies. The number of neutrophils in bronchoalveolar lavage fluid (BALF) and levels of myeloperoxidase activity in lung homogenates were also measured. Results Lipopolysaccharide enhanced the immunoreactivity of iNOS, nitrotyrosine, and chlorotyrosine in alveolar wall cells, alveolar macrophages, and neutrophils. Leukocyte depletion by cyclophosphamide and inhibition of leukocyte accumulation in the lungs by NO inhalation did not eliminate the increase in iNOS immunoreactivity in alveolar macrophages after lipopolysaccharide treatment, but nitrotyrosine and chlorotyrosine were not produced in these cells. Tyrosine nitration in response to lipopolysaccharide was associated with increases in neutrophil count in BALF and in myeloperoxidase activity in lung homogenates, whereas NO inhalation suppressed the neutrophil count in BALF and reduced tyrosine nitration and chlorination. Conclusions These findings suggest that myeloperoxidase pathway has a role in tyrosine nitration in the lungs of lipopolysaccharide-treated rats, and that NO inhalation during early phase of inflammation does not increase but rather decreases tyrosine nitration and chlorination, possibly by reducing neutrophil sequestration.

The health effects of silver nanoparticles (AgNPs) have not been well investigated, despite AgNPs now being widely used in consumer products. We investigated the metabolic behavior and toxicity of AgNPs in comparison to silver nitrate (AgNO3) both in vivo and in vitro. AgNPs (20 nm diameter) suspended in 1% albumin solution or AgNO3 solution was injected into the mouse lung. Less than 1% of the initial dose of AgNPs and more than 7% of the initial dose of AgNO3 was recovered in the liver 4h after administration, suggesting that the ionic form of silver was absorbed by the lung tissue and entered the systemic circulation more efficiently than AgNPs. The pro-inflammatory cytokine, IL-1β, and neutrophils in bronchoalveolar lavage fluid (BALF) increased following intratracheal instillation of AgNPs or AgNO3. AgNO3 recruited more neutrophils in the alveolar space than did AgNPs. In the in vitro study, AgNO3 was more cytotoxic than 20, 60, or 100 nm diameter AgNPs in a mouse macrophage cell line (J774.1). To investigate the intracellular distribution of Ag in detail, J774.1 cells were exposed to AgNO3 or 20 nm AgNPs and the distribution of Ag to cytosolic proteins was investigated using HPLC-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Ag was mainly distributed to metallothioneins (MT) and to high molecular weight proteins in AgNO3- and AgNPs-exposed cells, respectively. Confocal laser microscopic examination of LysoTracker(®)-labeled cells indicated that AgNPs were colocalized with lysosomes in J774.1 cells. These results suggest that AgNPs were transported to lysosomes and only gradually dissolved in the macrophages, causing milder inflammatory stimulation in the mouse lung compared to AgNO3.

Epidemiological studies have reported an increased risk of cardiopulmonary and lung cancer mortality associated with increasing exposure to air pollution. Ambient particulate matter consists of primary particles emitted directly from diesel engine vehicles and secondary organic aerosols (SOAs) are formed by oxidative reaction of the ultrafine particle components of diesel exhaust (DE) in the atmosphere. However, little is known about the relationship between exposure to SOA and central nervous system functions. Recently, we have reported that an acute single intranasal instillation of SOA may induce inflammatory response in lung, but not in brain of adult mice. To clarify the whole body exposure effects of SOA on central nervous system functions, we first created inhalation chambers for diesel exhaust origin secondary organic aerosols (DE-SOAs) produced by oxidation of diesel exhaust particles caused by adding ozone. Male BALB/c mice were exposed to clean air (control), DE and DE-SOA in inhalation chambers for one or three months (5 h/day, 5 days/week) and were examined for memory function using a novel object recognition test and for memory function-related gene expressions in the hippocampus by real-time RT-PCR. Moreover, female mice exposed to DE-SOA for one month were mated and maternal behaviors and the related gene expressions in the hypothalamus examined. Novel object recognition ability and N-methyl-D-aspartate (NMDA) receptor expression in the hippocampus were affected in male mice exposed to DE-SOA. Furthermore, a tendency to decrease maternal performance and significantly decreased expression levels of estrogen receptor (ER)-a, and oxytocin receptor were found in DE-SOA exposed dams compared with the control. This is the first study of this type and our results suggest that the constituents of DE-SOA may be associated with memory function and maternal performance based on the impaired gene expressions in the hippocampus and hypothalamus, respectively.

Alveolar macrophages meet various types of particulate substances deposited deep in the lung. We report differences in biologic responses of alveolar macrophages between phagocytosis of fine spherical and fibrous particles. Although titanium dioxide (TiO(2)) is thought to be biologically inert, the cytotoxicity of fibrous TiO(2) (F-TiO(2)) was much higher than spherical TiO(2) (S-TiO(2)). Differential display and the subsequent Northern blot analysis indicated that transcription of krox-20/egr-2 gene was slightly and greatly upregulated in S- and F-TiO(2)-exposed alveolar macrophages, respectively. The messenger RNA (mRNA) level of krox-20/egr-2 increased up to 8 h in F-TiO(2)-exposed alveolar macrophages, whereas krox-20/egr-2 mRNA level was transiently increased in response to adhesion to the culture dish. Stimulation with lipopolysaccharide also increased krox-20/egr-2 mRNA level transiently, although the mRNA level rebounded after 8 h. The analysis with 5' rapid amplification of complementary DNA ends suggested that there is a heterogeneity in the upstream region of this gene (krox-20/egr-2 and krox-20H1; accession numbers AB032420 and AB032419, respectively). The polymerase chain reaction analysis with specific primers for krox-20/egr-2 and krox-20H1 indicated that both genes were almost equally upregulated after either adhesion to the plastic dish or phagocytosis of F-TiO(2). These results suggest that both krox-20/egr-2 and krox-20H1 are implicated in adhesion and phagocytosis, and that the expression of krox-20 may reflect interaction with foreign substances and adhesion in alveolar macrophages.