Microglia-specific overexpression of α-synuclein leads to severe dopaminergic neurodegeneration by phagocytic exhaustion and oxidative toxicity

Recent findings in human samples and animal models support the involvement of inflammation in the development of Parkinson's disease. Nevertheless, it is currently unknown whether microglial activation constitutes a primary event in neurodegeneration. We generated a new mouse model by lentiviral-mediated selective α-synuclein (αSYN) accumulation in microglial cells. Surprisingly, these mice developed progressive degeneration of dopaminergic (DA) neurons without endogenous αSYN aggregation. Transcriptomics and functional assessment revealed that αSYN-accumulating microglial cells developed a strong reactive state with phagocytic exhaustion and excessive production of oxidative and proinflammatory molecules. This inflammatory state created a molecular feed-forward vicious cycle between microglia and IFNγ-secreting immune cells infiltrating the brain parenchyma. Pharmacological inhibition of oxidative and nitrosative molecule production was sufficient to attenuate neurodegeneration. These results suggest that αSYN accumulation in microglia induces selective DA neuronal degeneration by promoting phagocytic exhaustion, an excessively toxic environment and the selective recruitment of peripheral immune cells.

Implication of a Key Region of Six Bacillus cereus Genes Involved in Siroheme Synthesis, Nitrite Reductase Production and Iron Cluster Repair in the Bacterial Response to Nitric Oxide Stress

Bacterial response to nitric oxide (NO) is of major importance for bacterial survival. NO stress is a main actor of the eukaryotic immune response and several pathogenic bacteria have developed means for detoxification and repair of the damages caused by NO. However, bacterial mechanisms of NO resistance by Gram-positive bacteria are poorly described. In the opportunistic foodborne pathogen Bacillus cereus, genome sequence analyses did not identify homologs to known NO reductases and transcriptional regulators, such as NsrR, which orchestrate the response to NO of other pathogenic or non-pathogenic bacteria. Using a transcriptomic approach, we investigated the adaptation of B. cereus to NO stress. A cluster of 6 genes was identified to be strongly up-regulated in the early phase of the response. This cluster contains an iron-sulfur cluster repair enzyme, a nitrite reductase and three enzymes involved in siroheme biosynthesis. The expression pattern and close genetic localization suggest a functional link between these genes, which may play a pivotal role in the resistance of B. cereus to NO stress during infection.

Synthesis and in vitro characterization of the genotoxic, mutagenic and cell-transforming potential of nitrosylated heme

Data from epidemiological studies suggest that consumption of red and processed meat is a factor contributing to colorectal carcinogenesis. Red meat contains high amounts of heme, which in turn can be converted to its nitrosylated form, NO-heme, when adding nitrite-containing curing salt to meat. NO-heme might contribute to colorectal cancer formation by causing gene mutations and could thereby be responsible for the association of (processed) red meat consumption with intestinal cancer. Up to now, neither in vitro nor in vivo studies characterizing the mutagenic and cell transforming potential of NO-heme have been published due to the fact that the pure compound is not readily available. Therefore, in the present study, an already existing synthesis protocol was modified to yield, for the first time, purified NO-heme. Thereafter, newly synthesized NO-heme was chemically characterized and used in various in vitro approaches at dietary concentrations to determine whether it can lead to DNA damage and malignant cell transformation. While NO-heme led to a significant dose-dependent increase in the number of DNA strand breaks in the comet assay and was mutagenic in the HPRT assay, this compound tested negative in the Ames test and failed to induce malignant cell transformation in the BALB/c 3T3 cell transformation assay. Interestingly, the non-nitrosylated heme control showed similar effects, but was additionally able to induce malignant transformation in BALB/c 3T3 murine fibroblasts. Taken together, these results suggest that it is the heme molecule rather than the NO moiety which is involved in driving red meat-associated carcinogenesis.

Ambient air pollution as a mediator in the pathway linking race/ethnicity to blood pressure elevation: The multi-ethnic study of atherosclerosis (MESA)

BACKGROUND

Racial/ethnic disparities in blood pressure and hypertension have been evident in previous studies, as were associations between race/ethnicity with ambient air pollution and those between air pollution with hypertension. The role of air pollution exposure to racial/ethnic differences in hypertension has not been explored.

OBJECTIVE

To assess the potential mediating effects of ambient air pollution on the association between race/ethnicity and blood pressure levels.

METHODS

We studied 6,463 White, Black, Hispanic and Chinese adults enrolled across 6 US cities. Systolic (SBP) and diastolic blood pressure (DBP) were measured at Exam 1 (2000-2002) and Exam 2 (2002-2004). Household-level annual average concentrations of fine particulate matter (PM_2.5), oxides of nitrogen (NO_X), and ozone (O₃) for the year 2000 were estimated for participants.

RESULTS

The difference in SBP levels by race/ethnicity that was related to higher PM_2.5 concentrations compared with White men ("indirect associations") was 0.3 (95% CI: 0.1, 0.6) mmHg for Black men, 0.3 (95% CI: 0.1, 0.6) mmHg for Hispanic men and 1.0 (95% CI: 0.2, 1.8) mmHg for Chinese men. Findings were similar although not statistically significant for women. PM_2.5 did not mediate racial/ethnic differences in DBP. Indirect associations were significant for O₃ for SBP among women and men and for DBP among men. In contrast, racial/ethnic disparities were attenuated due to exposure to NO_X.

CONCLUSION

Racial disparities in blood pressure were reduced after accounting for PM_2.5 and ozone while increased after accounting for NO_X.

Nitric oxide in plants: pro- or anti-senescence

Senescence is a regulated process of tissue degeneration that can affect any plant organ and consists of the degradation and remobilization of molecules to other growing tissues. Senescent organs display changes at the microscopic level as well as modifications to internal cellular structure and differential gene expression. A large number of factors influencing senescence have been described including age, nutrient supply, and environmental interactions. Internal factors such as phytohormones also affect the timing of leaf senescence. A link between the senescence process and the production of nitric oxide (NO) in senescing tissues has been known for many years. Remarkably, this link can be either a positive or a negative correlation depending upon the organ. NO can be both a signaling or a toxic molecule and is known to have multiple roles in plants; this review considers the duality of NO roles in the senescence process of two different plant organs, namely the leaves and root nodules.

H2 O2 -induced microvessel barrier dysfunction: the interplay between reactive oxygen species, nitric oxide, and peroxynitrite

Elevated H2 O2 is implicated in many cardiovascular diseases. We previously demonstrated that H2 O2 -induced endothelial nitric oxide synthase (eNOS) activation and excessive NO production contribute to vascular cell injury and increases in microvessel permeability. However, the mechanisms of excessive NO-mediated vascular injury and hyperpermeability remain unknown. This study aims to examine the functional role of NO-derived peroxynitrite (ONOO- ) in H2 O2 -induced vascular barrier dysfunction by elucidating the interrelationships between H2 O2 -induced NO, superoxide, ONOO- , and changes in endothelial [Ca2+ ]i and microvessel permeability. Experiments were conducted on intact rat mesenteric venules. Microvessel permeability was determined by measuring hydraulic conductivity (Lp). Endothelial [Ca2+ ]i , NO, and O2- were assessed with fluorescence imaging. Perfusion of vessels with H2 O2 (10 µmol/L) induced marked productions of NO and O2- , resulting in extensive protein tyrosine nitration, a biomarker of ONOO- . The formation of ONOO- was abolished by inhibition of NOS with NG -Methyl-L-arginine. Blocking NO production or scavenging ONOO- by uric acid prevented H2 O2 -induced increases in endothelial [Ca2+ ]i and Lp. Additionally, the application of exogenous ONOO- to microvessels induced delayed and progressive increases in endothelial [Ca2+ ]i and microvessel Lp, a pattern similar to that observed in H2 O2 -perfused vessels. Importantly, ONOO- caused further activation of eNOS with amplified NO production. We conclude that the augmentation of NO-derived ONOO- is essential for H2 O2 -induced endothelial Ca2+ overload and progressively increased microvessel permeability, which is achieved by self-promoted amplifications of NO-dependent signaling cascades. This novel mechanism provides new insight into the reactive oxygen and/or reactive nitrogen species-mediated vascular dysfunction in cardiovascular diseases.

Nitric oxide radicals are emitted by wasp eggs to kill mold fungi

Detrimental microbes caused the evolution of a great diversity of antimicrobial defenses in plants and animals. Insects developing underground seem particularly threatened. Here we show that the eggs of a solitary digger wasp, the European beewolf Philanthus triangulum, emit large amounts of gaseous nitric oxide (NO⋅) to protect themselves and their provisions, paralyzed honeybees, against mold fungi. We provide evidence that a NO-synthase (NOS) is involved in the generation of the extraordinary concentrations of nitrogen radicals in brood cells (~1500 ppm NO⋅ and its oxidation product NO2⋅). Sequencing of the beewolf NOS gene revealed no conspicuous differences to related species. However, due to alternative splicing, the NOS-mRNA in beewolf eggs lacks an exon near the regulatory domain. This preventive external application of high doses of NO⋅ by wasp eggs represents an evolutionary key innovation that adds a remarkable novel facet to the array of functions of the important biological effector NO⋅.

Integrated lipid production, CO2 fixation, and removal of SO2 and NO from simulated flue gas by oleaginous Chlorella pyrenoidosa

CO₂, SO₂, and NO are the main components of flue gas and can cause serious environmental issues. Utilization of these compounds in oleaginous microalgae cultivation not only could reduce air pollution but could also produce feedstock for biodiesel production. However, the continuous input of SO₂ and NO inhibits microalgal growth. In this study, the toxicity of simulated flue gas (15% CO₂, 0.03% SO₂, and 0.03% NO, balanced with N₂) was reduced through automatic pH feedback control. Integrated lipid production and CO₂ fixation with the removal of SO₂ and NO was achieved. Using this technique, a lipid content of 38.0% DW was achieved in Chlorella pyrenoidosa XQ-20044. The lipid composition and fatty acid profile indicated that lipid production by C. pyrenoidosa XQ-20044 cultured with flue gas is suitable as a biodiesel feedstock; 81.2% of the total lipids were neutral lipids and 99.5% of the total fatty acids were C16 and C18. The ratio of saturated fatty acids to monounsaturated fatty acids in the microalgal lipid content was 74.5%. In addition, CO₂, SO₂, and NO from the simulated flue gas were fixed and converted to biomass and lipids with a removal efficiency of 95.9%, 100%, and 84.2%, respectively. Furthermore, the utilization efficiencies of CO₂, SO₂, and NO were equal to or very close to their removal efficiencies. These results provide a novel strategy for combining biodiesel production with biofixation of flue gas.

Acute exposure to diesel exhaust induces central nervous system stress and altered learning and memory in honey bees

For effective foraging, many insect pollinators rely on the ability to learn and recall floral odours, behaviours that are associated with a complex suite of cellular processes. Here, we investigated how acute exposure to a high-dose of diesel exhaust (containing 19.8 and 17.5 ppm of NO and NO2, respectively) affected associative learning behaviour of honey bees (Apis mellifera) and expression of a ubiquitous heat shock protein, HSP70, in their central nervous system (CNS). To determine whether exposure to diesel exhaust would alter their tolerance to a subsequent abiotic stress, we further subjected individuals to heat stress. Diesel exhaust exposure decreased honey bees' ability to learn and recall a conditioned odour stimulus. Whilst there was no significant difference in CNS HSP70 expression between honey bees exposed to either diesel exhaust or clean air across the entire duration of the experiment (3.5 h), there was a significant effect of time and a significant interaction between exposure treatment and time. This interaction was investigated using correlation analyses, which demonstrated that only in the diesel exhaust exposed honey bees was there a significant positive correlation between HSP70 expression and time. Furthermore, there was a 44% reduction in honey bee individuals that were able to recall the odour 72 h after diesel exposure compared with clean air control individuals. Moreover, diesel exhaust affected A. mellifera in a way that reduced their ability to survive a second subsequent stressor. Such negative effects of air pollution on learning, recall, and stress tolerance has potential to reduce foraging efficiency and pollination success of individual honey bees.

The association of early-life exposure to air pollution with lung function at ~17.5 years in the "Children of 1997" Hong Kong Chinese Birth Cohort

BACKGROUND

Early-life air pollution exposure is associated with lung function in children and adolescents. However, whether the association of prenatal and early postnatal exposure to air pollution with lung function continues into adulthood remains unclear.

OBJECTIVE

To investigate the associations of early exposure to air pollution with lung function at ~17.5 years in a non-western developed setting with more concentrated air pollutants.

METHODS

We examined the associations of exposure to particular matter with an aerodynamic diameter of <10 μm (PM₁₀), nitrogen dioxides (NO₂), nitric oxide (NO), sulfur dioxide (SO₂) in standard deviations (SD)) at different early life stages with lung function (indicated by forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁) and forced expiratory flow at 25%-75% of the pulmonary volume (FEF_25%-75%)) in SD at ~17.5 years, personal history of wheezing and asthma in the population-representative Hong Kong Chinese birth cohort "Children of 1997"(n = 2942).

RESULTS

Higher in utero and infancy and toddlerhood NO₂ were associated with lower FEV₁ (-0.022, 95% confidence interval (CI) -0.029 to -0.015 and - 0.026, 95% CI -0.033 to -0.019), FEV₁/FVC (-0.035, 95% CI -0.050 to -0.021 and -0.052, 95% CI -0.066 to -0.038) and FEF_25%-75% (-0.031, 95% CI -0.040 to -0.022 and -0.043, 95% CI -0.051 to -0.035). A similar association was observed for NO. Weak associations of NO₂ and NO with FVC were observed (-0.011, 95% CI -0.018 to -0.003 and -0.010, 95% CI -0.020 to -0.001). NO_x was associated with higher risk of wheezing (1.08, 95% CI 1.03 to 1.14) but not asthma (1.02, 95% CI 0.94 to 1.11). SO₂ and PM₁₀ were not clearly associated with lung function, wheezing or asthma.

CONCLUSION

Our findings suggest that early exposure to air pollution from NO₂ may have long-term effects on lung function, which could affect respiratory health throughout life.

Environmental exposure to polycyclic aromatic hydrocarbons, kitchen ventilation, fractional exhaled nitric oxide, and risk of diabetes among Chinese females

Diabetes is related to exposure to polycyclic aromatic hydrocarbons (PAHs), inflammation in the body, and housing characters. However, associations of urinary monohydroxy-PAHs (OH-PAHs) or fractional exhaled nitric oxide (FeNO) with diabetes risk in relation to housing characters are unclear. In this study, 2645 individuals were drawn from the baseline survey of the Wuhan-Zhuhai Cohort Study. Associations of diabetes with urinary OH-PAHs or FeNO among cooking participants were estimated using logistic regression models. Among women with self-cooking meals, urinary OH-PAH levels were positively associated with diabetes risk (P < .05); the cooking women with high FeNO (≥25 ppb) had a 59% increase in the risk of diabetes (OR: 1.59, 95% CI: 1.06, 2.38), compared with those with low FeNO (<25 ppb). The cooking women with use of kitchen exhaust fans/hoods had a 52% decrease in the risk of diabetes (OR: 0.48, 95% CI: 0.27, 0.84), compared with those with nonuse of kitchen exhaust fans/hoods. The results indicated that the cooking women had an elevated risk of diabetes, which may be partly explained by an increase in the PAH body burden and higher inflammatory responses. Use of kitchen exhaust fan/hood can be associated with a lower risk of diabetes.

The Effect of Nitric Oxide Pollution on Oxidative Stress in Pregnant Women Living in Durban, South Africa

The purpose of the study was to evaluate the effect nitric oxide (NO _x ) pollution had on maternal serum 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OHdG) levels and neonatal outcomes in pregnant women living in Durban, South Africa (SA). Women, in their third trimester with singleton pregnancies, were recruited from the heavily industrialised south (n = 225) and less industrialised north (n = 152). Biomarker levels of serum 8-OHdG concentrations were analysed, and the women were genotyped for glutathione-S-transferases pi 1 (GSTP1) and glutathione-S-transferases mu 1 (GSTM1) polymorphisms. The level of NO _x pollution in the two regions was determined by using land use regression modelling. The serum 8-OHdG was shown to correlate significantly with NO _x levels; this relationship was strengthened in the south (p < 0.05). This relationship was still observed after adjusting for maternal characteristics. GSTP1 was significantly associated with the south region, where the variant (AG+GG) genotype was associated with increased 8-OHdG levels as a result of NO _x exposure (p < 0.05). GSTM1 null genotype was associated with a positive correlation between NO _x and 8-OHdG levels (p < 0.05). NO _x levels were found marginally to reduce gestational age (p < 0.05) with mothers carrying male neonates. Variant GSTP1 and living in the north were factors that contributed to gestational age reduction (p < 0.05). Our study demonstrated that NO _x exposure resulted in increased 8-OHdG levels in pregnant women living in Durban, SA, which led to gestational age reduction. The GSTP1 variant increased susceptibility of individuals to harmful effects of NO _x .

Genipin Inhibits the Induction of Inducible Nitric Oxide Synthase Through the Inhibition of NF-κB Activation in Rat Hepatocytes

BACKGROUND/AIMS

Genipin is a component of Japanese traditional herbal medicine (Kampo), inchinkoto, and is used for the treatment of various liver injuries. However, there are few scientific evidence for its anti-inflammatory effects and mechanisms. In inflamed liver, proinflammatory cytokines including tumor necrosis factor (TNF)-α and interleukin (IL)-1β stimulate liver cells, followed by the expression of inducible nitric oxide synthase (iNOS). Excessive levels of NO produced by iNOS have been implicated as one of the factors in liver injury. Thus it is essential to inhibit iNOS induction for the prevention of liver injury. In this study, we examined IL-1β-stimulated hepatocytes as a simple "in vitro liver injury model" to investigate liver protective effects of genipin.

METHODS

Primary cultured rat hepatocytes were treated with IL-1β in the presence or absence of genipin. The induction of NO production and iNOS, and its signaling pathway were analyzed.

RESULTS

In IL-1β-stimulated hepatocytes, genipin inhibited the production of NO dose- and timedependently, and reduced the levels of iNOS protein and its mRNA expression. Genipin also reduced mRNA expressions of TNF-α and IL-6. Genipin inhibited two essential signaling pathways for iNOS induction, IκB degradation/NF-κB activation and type I IL-1 receptor upregulation. Transfection experiments revealed that genipin decreased the expression of iNOS mRNA through both inhibitions of the promoter activation and mRNA stabilization. Delayed administration of genipin after IL-1β addition also inhibited iNOS induction.

CONCLUSION

Genipin influenced the induction of inflammatory mediators, iNOS and TNF-α, in part through the inhibition of NF-κB activation in hepatocytes. Genipin may have therapeutic potential for organ injuries including liver.

Lead ions abrogate lipopolysaccharide-induced nitric monoxide toxicity by reducing the expression of STAT1 and iNOS

Lead is a widespread environmental pollutant and the highly poisonous metal compromises multiple organs in the body. Among other tissues and cells, lead ions (Pb(2+)) can affect macrophages and microglia cells. The present study observed a concentration-dependent protection of BV-2 microglia and RAW 264.7 macrophages by Pb(2+) against lipopolysaccharide (LPS)-induced toxicity. Both cell lines are potent producers of two substances that have previously been shown to mediate cytotoxic effects of LPS. These are the pro-inflammatory cytokine tumor necrosis factor (TNF)-α and nitric monoxide (NO), which creates nitrosative stress, hampering the distribution of invading pathogens and tumor cells. While the expression of TNF-α was unaffected by Pb(2+), the production of NO was significantly inhibited. Moreover, blocking NO synthesis by low molecular weight inhibitors prevented LPS-mediated toxicity, confirming the role of NO in these events. Pb(2+) exposure led to a downregulation of LPS-induced expression of the transcription factor STAT1, which is involved in iNOS transcription. Moreover, iNOS mRNA and protein levels were reduced in the presence of Pb(2+), explaining the reduced formation of NO and a subsequent increase of cellular viability in vitro. In vivo, the effect might limit collateral damage caused by excessive NO production, but also impair the efficiency of NO as a central mediator of the defense against various pathogens.

A Preliminary Assessment of the Role of Ambient Nitric Oxide Exposure in Hospitalization with Respiratory Syncytial Virus Bronchiolitis

Some in vitro studies have indicated a possible link between respiratory syncytial virus (RSV) infection and exposure to Nitric Oxide (NO). However, these studies used much higher NO concentrations than normally found in the ambient environment. This preliminary study explored whether an association was present with short-term exposure to NO in the environment. RSV-related admission data between November 2011 and February 2012 were obtained from Sheffield Children's Hospital. The dates of admission were linked to contemporaneous ambient NO derived from sentinel air monitors. The case-crossover design was used to study the relationship between daily RSV admissions and NO, controlling for temperature and relative humidity. We found little evidence of association between daily RSV admission rates and exposure to ambient NO at different lags or average exposure across several lags. The findings should, however, be viewed with caution due to the low number of events observed during the time frame. It is possible that the apparent lack of association may be accounted for by the timing of the seasonal RSV epidemic in relation to peaks in NO concentrations. A larger study incorporating a wider range of RSV and NO peaks would determine whether said peaks enhanced the number of RSV hospitalizations in children.

S-Nitrosated Polypropylene Sulfide Nanoparticles for Thiol-Dependent Transnitrosation and Toxicity Against Adult Female Filarial Worms

A synthetic polymer nanoparticle formulation utilizing the physiological nitrosothiol chemistry for nitric oxide delivery is shown. Toxicity of S-nitroso nanoparticles against adult female Brugia malayi worms, which are responsible for lymphatic filariasis, is dependent on nitric oxide release through transnitrosation as S-nitrosocysteine, a potent endogenous nitric oxide donor.

Peculiarities of DNA damage caused by exogenous nitric oxide combined with fractionated low dose ionizing radiation in normal and tumor cells

The aim of this study was to investigate the reaction of normal and tumor cells to genotoxic effect of widespread environmental factors - exogenous nitric oxides and ionizing radiation.

METHODS

The animals were treated with NO (125 mg/m(3)) and low dose ionizing radiation (10 acute exposures with 0.1 Gy each). Genotoxicity was estimated in vivo in rats peripheral blood lymphocytes, bone marrow cells and tumor cells of Guerin carcinoma. DNA damages were assessed by alkaline single-cell gel electrophoresis.

RESULTS

Exogenous nitric oxides as well as irradiation caused significant increase of DNA damage in all types of investigated cells. The genotoxic effect increased in the order: peripheral blood lymphocytes < bone marrow cells < Guerin carcinoma cells. The greatest genotoxic effect was registered in Guerin carcinoma cells on terminal phase of tumor growth in rats exposed to NO and low dose ionizing radiation.

CONCLUSIONS

Long-term exposure to common environmental factors (exogenous nitric oxides and ionizing radiation) capable to induce DNA damage in different cells. Severity of the genotoxic effect depends on cell type and nature of impacting factors. NO caused more significant DNA damage than low dose ionizing radiation but the highest level of DNA damage was observed after their joint action. Obtained results confirm the real threat of cancer risk increase under combined action of common environmental factors of different nature.

Part 1. Assessment of carcinogenicity and biologic responses in rats after lifetime inhalation of new-technology diesel exhaust in the ACES bioassay

The Health Effects Institute and its partners conceived and funded a program to characterize the emissions from heavy-duty diesel engines compliant with the 2007 and 2010 on-road emissions standards in the United States and to evaluate indicators of lung toxicity in rats and mice exposed repeatedly to 2007-compliant new-technology diesel exhaust (NTDE*). The a priori hypothesis of this Advanced Collaborative Emissions Study (ACES) was that 2007-compliant on-road diesel emissions "... will not cause an increase in tumor formation or substantial toxic effects in rats and mice at the highest concentration of exhaust that can be used ... although some biological effects may occur." This hypothesis was tested at the Lovelace Respiratory Research Institute (LRRI) by exposing rats by chronic inhalation as a carcinogenicity bioassay. Indicators of pulmonary toxicity in rats were measured after 1, 3, 12, 24, and 28-30 months of exposure. Similar indicators of pulmonary toxicity were measured in mice, as an interspecies comparison of the effects of subchronic exposure, after 1 and 3 months of exposure. A previous HEI report (Mauderly and McDonald 2012) described the operation of the engine and exposure systems and the characteristics of the exposure atmospheres during system commissioning. Another HEI report described the biologic responses in mice and rats after subchronic exposure to NTDE (McDonald et al. 2012). The primary motivation for the present chronic study was to evaluate the effects of NTDE in rats in the context of previous studies that had shown neoplastic lung lesions in rats exposed chronically to traditional technology diesel exhaust (TDE) (i.e., exhaust from diesel engines built before the 2007 U.S. requirements went into effect). The hypothesis was largely based on the marked reduction of diesel particulate matter (DPM) in NTDE compared with emissions from older diesel engine and fuel technologies, although other emissions were also reduced. The DPM component of TDE was considered the primary driver of lung tumorigenesis in rats exposed chronically to historical diesel emissions. Emissions from a 2007-compliant, 500-horsepower-class engine and after treatment system operated on a variable-duty cycle were used to generate the animal inhalation test atmospheres. Four groups were exposed to one of three concentrations (dilutions) of exhaust combined with crankcase emissions, or to clean air as a negative control. Dilutions of exhaust were set to yield average integrated concentrations of 4.2, 0.8, and 0.1 ppm nitrogen dioxide (NO2). Exposure atmospheres were analyzed by daily measurements of key effects of NTDE in the present study were generally consistent with those observed previously in rats exposed chronically to NO2 alone. This suggests that NO2 may have been the primary driver of the biologic responses to NTDE in the present study. There was little evidence of effects characteristic of rats exposed chronically to high concentrations of DPM in TDE, such as an extensive accumulation of DPM within alveolar macrophages and inflammation leading to neoplastic transformation of epithelia and lung tumors. components and periodic detailed physical-chemical characterizations. Exposures were conducted 16 hours/day (overnight, during the rats' most active period), 5 days/week. Responses to exposure were evaluated via hematology, serum chemistry, bronchoalveolar lavage (BAL), lung cell proliferation, histopathology, and pulmonary function. The exposures were accomplished as planned, with average integrated exposure concentrations within 20% of the target dilutions. The major components from exhaust were the gaseous inorganic compounds, nitrogen monoxide (NO), NO2, and carbon monoxide (CO). Minor components included low concentrations of DPM and volatile and semi-volatile organic compounds (VOCs and SVOCs). Among the more than 100 biologic response variables evaluated, the majority showed no significant difference from control as a result of exposure to NTDE. The major outcome of this study was the absence of pre-neoplastic lung lesions, primary lung neoplasia, or neoplasia of any type attributable to NTDE exposure. The lung lesions that did occur were minimal to mild, occurred only at the highest exposure level, and were characterized by an increased number and prominence of basophilic epithelial cells (considered reactive or regenerative) lining distal terminal bronchioles, alveolar ducts, and adjacent alveoli (termed in this report "Hyperplasia; Epithelial; Periacinar"), which often had a minimal increase in subjacent fibrous stroma (termed "Fibrosis; Interstitial; Periacinar"). Slight epithelial metaplastic change to a cuboidal morphology, often demonstrating cilia, was also noted in some animals (termed "Bronchiolization"). In addition to the epithelial proliferation, there was occasionally a subtle accumulation of pulmonary alveolar macrophages (termed "Accumulation; Macrophage") in affected areas. The findings in the lung progressed slightly from 3 to 12 months, without further progression between 12 months and the final sacrifice at 28 or 30 months. In addition to the histologic findings, there were biochemical changes in the lung tissue and lavage fluid that indicated mild inflammation and oxidative stress. Generally, these findings were observed only at the highest exposure level. There was also a mild progressive decrease in pulmonary function, which was more consistent in females than males. Limited nasal epithelial changes resulted from NTDE exposure, including increases in minor olfactory epithelial degeneration, hyperplasia, and/or metaplasia. Increases in these findings were present primarily at the highest exposure level, and their minor and variable nature renders their biologic significance uncertain. Overall, the findings of this study demonstrated markedly less severe biologic responses to NTDE than observed previously in rats exposed similarly to TDE. Further, the effects of NTDE in the present study were generally consistent with those observed previously in rats exposed chronically to NO2 alone. This suggests that NO2 may have been the primary driver of the biologic responses to NTDE in the present study. There was little evidence of effects characteristic of rats exposed chronically to high concentrations of DPM in TDE, such as an extensive accumulation of DPM within alveolar macrophages and inflammation leading to neoplastic transformation of epithelia and lung tumors.

Myoglobin functions in the heart

The physiological role of myoglobin (Mb) within the heart depends on its oxygenation state. The myocardium exhibits a broad oxygen partial pressure (pO2) spectrum with a transmural gradient from the epicardial to the subendocardial layer, ranging from arterial values to an average of 19.3 mm Hg down to 0 mm Hg. The function of Mb as an O2 storage depot is well appreciated, especially during systolic compression. In addition, Mb controls myocardial nitric oxide (NO) homeostasis and thus modulates mitochondrial respiration under physiological and pathological conditions. We recently discovered the role of Mb as a myocardial O2 sensor; in its oxygenated state Mb scavenges NO, protecting the heart from the deleterious effects of excessive NO. Under hypoxia, however, deoxygenated Mb changes its role from an NO scavenger to an NO producer. The NO produced protects the cell from short phases of hypoxia and from myocardial ischemia/reperfusion injury. In this review we summarize the traditional and novel aspects of Mb and its (patho)physiological role in the heart.

Treatment of tumors with vitamin E suppresses myeloid derived suppressor cells and enhances CD8+ T cell-mediated antitumor effects

Vitamin E has been shown to have strong anticarcinogenic properties, including antioxidant characteristics, making it an ideal candidate for use in combination with immunotherapies that modify the tumor microenvironment. The tumor microenvironment contains immunosuppressive components, which can be diminished, and immunogenic components, which can be augmented by immunotherapies in order to generate a productive immune response. In the current study, we employ the α-tocopherol succinate isomer of vitamin E to reduce immunosuppression by myeloid derived suppressor cells (MDSCs) as well as adoptive transfer of antigen-specific CD8+ T cells to generate potent antitumor effects against the HPV16 E7-expressing TC-1 tumor model. We show that vitamin E alone induces necrosis of TC-1 cells and elicits antitumor effects in TC-1 tumor-bearing mice. We further demonstrate that vitamin E reverses the suppression of T cell activation by MDSCs and that this effect is mediated in part by a nitric oxide-dependent mechanism. Additionally, treatment with vitamin E reduces the percentage of MDSCs in tumor loci, and induces a higher percentage of T cells, following T cell adoptive transfer. Finally, we demonstrate that treatment with vitamin E followed by E7-specific T cell adoptive transfer experience elicits potent antitumor effects in tumor-bearing mice. Our data provide additional evidence that vitamin E has anticancer properties and that it has promise for use as an adjuvant in combination with a variety of cancer therapies.

Human DNA damage by the synergistic action of 4-aminobiphenyl and nitric oxide: an immunochemical study

4-Aminobiphenyl (4-ABP), an aromatic amine is a major environmental carcinogen found mainly in cigarette smoke. It has been vastly implicated in mutagenesis and cancer development. In this study, commercially available human placental DNA was exposed to 4-ABP (1.3 mM) in presence of sodium nitroprusside (SNP; 8 mM) at 37°C for 3 h. The 4-ABP + SNP-mediated structural changes in human DNA were studied by ultraviolet, circular dichroism and fluorescence spectroscopy, thermal melting profile, agarose gel electrophoresis, and nuclease S1 digestibility assay. Spectroscopical analysis and melting temperature studies suggest structural perturbations in the DNA as a result of modification. This might be due to generation of single-stranded regions and destabilization of hydrogen bonds. Modification was also visualized in agarose gel electrophoresis. Furthermore, nuclease S1 digestibility confirmed the generation of single strand breaks. Rabbits challenged with 4-ABP-SNP-modified human DNA-induced high-titer immunogen-specific antibodies, which showed Cross-reaction with modified/unmodified DNA bases and ss-DNA in competitive inhibition assay. The immunogen specificity of induced antibodies against 4-ABP-SNP-modified human DNA was further confirmed in gel retardation assay. It may be concluded that induction of anti-modified DNA antibodies could be due to perturbation in the DNA structure and its subsequent recognition by immunoregulatory cells as a foreign molecule.

Therapeutic hypercapnia prevents inhaled nitric oxide-induced right-ventricular systolic dysfunction in juvenile rats

Chronic pulmonary hypertension in the neonate and infant frequently presents with right-ventricular (RV) failure. Current clinical management may include protracted treatment with inhaled nitric oxide (iNO), with the goal of reducing RV afterload. We have previously reported that prolonged exposure to iNO causes RV systolic dysfunction in the chronic hypoxia-exposed juvenile rat, which was prevented by a peroxynitrite decomposition catalyst. Given that inhalation of CO2 (therapeutic hypercapnia) may limit oxidative stress and upregulated cytokine expression in the lung and other organs, we hypothesized that therapeutic hypercapnia would attenuate cytokine-mediated nitric oxide synthase (NOS) upregulation, thus limiting peroxynitrite generation. Sprague-Dawley rat pups were exposed to chronic hypoxia (13% O2) from postnatal day 1 to 21, while receiving iNO (20 ppm) from day 14 to 21, with or without therapeutic hypercapnia (10% CO2). Therapeutic hypercapnia completely normalized RV systolic function, RV hypertrophy, and remodeling of pulmonary resistance arteries in animals exposed to iNO. Inhaled nitric oxide-mediated increases in RV peroxynitrite, apoptosis, and contents of tumor necrosis factor (TNF)-α, interleukin (IL)-1α, and NOS-2 were all attenuated by therapeutic hypercapnia. Inhibition of NOS-2 activity with 1400 W (1 mg/kg/day) prevented iNO-mediated upregulation of peroxynitrite and led to improved RV systolic function. Blockade of IL-1 receptor signaling with anakinra (500 mg/kg/day) decreased NOS-2 content and had similar effects compared to NOS-2 inhibition on iNO-mediated effects, whereas blockade of TNF-α signaling with etanercept (0.4 mg/kg on alternate days) had no effects on these parameters. We conclude that therapeutic hypercapnia prevents the adverse effects of sustained exposure to iNO on RV systolic function by limiting IL-1-mediated NOS-2 upregulation and consequent nitration. Therapeutic hypercapnia also acts synergistically with iNO in normalizing RV hypertrophy, vascular remodeling, and raised pulmonary vascular resistance secondary to chronic hypoxia.

Assessment of the capacity of vehicle cabin air inlet filters to reduce diesel exhaust-induced symptoms in human volunteers

BACKGROUND

Exposure to particulate matter (PM) air pollution especially derived from traffic is associated with increases in cardiorespiratory morbidity and mortality. In this study, we evaluated the ability of novel vehicle cabin air inlet filters to reduce diesel exhaust (DE)-induced symptoms and markers of inflammation in human subjects.

METHODS

Thirty healthy subjects participated in a randomized double-blind controlled crossover study where they were exposed to filtered air, unfiltered DE and DE filtered through two selected particle filters, one with and one without active charcoal. Exposures lasted for one hour. Symptoms were assessed before and during exposures and lung function was measured before and after each exposure, with inflammation assessed in peripheral blood five hours after exposures. In parallel, PM were collected from unfiltered and filtered DE and assessed for their capacity to drive damaging oxidation reactions in a cell-free model, or promote inflammation in A549 cells.

RESULTS

The standard particle filter employed in this study reduced PM10 mass concentrations within the exposure chamber by 46%, further reduced to 74% by the inclusion of an active charcoal component. In addition use of the active charcoal filter was associated by a 75% and 50% reduction in NO2 and hydrocarbon concentrations, respectively. As expected, subjects reported more subjective symptoms after exposure to unfiltered DE compared to filtered air, which was significantly reduced by the filter with an active charcoal component. There were no significant changes in lung function after exposures. Similarly diesel exhaust did not elicit significant increases in any of the inflammatory markers examined in the peripheral blood samples 5 hour post-exposure. Whilst the filters reduced chamber particle concentrations, the oxidative activity of the particles themselves, did not change following filtration with either filter. In contrast, diesel exhaust PM passed through the active charcoal combination filter appeared less inflammatory to A549 cells.

CONCLUSIONS

A cabin air inlet particle filter including an active charcoal component was highly effective in reducing both DE particulate and gaseous components, with reduced exhaust-induced symptoms in healthy volunteers. These data demonstrate the effectiveness of cabin filters to protect subjects travelling in vehicles from diesel exhaust emissions.

Integrating health on air quality assessment--review report on health risks of two major European outdoor air pollutants: PM and NO₂

Quantifying the impact of air pollution on the public's health has become an increasingly critical component in policy discussion. Recent data indicate that more than 70% of the world population lives in cities. Several studies reported that current levels of air pollutants in urban areas are associated with adverse health risks, namely, cardiovascular diseases and lung cancer. IARC recently classified outdoor air pollution and related particulate matter (PM) as carcinogenic to humans. Despite the air quality improvements observed over the last few years, there is still continued widespread exceedance within Europe, particularly regarding PM and nitrogen oxides (NOx). The European Air Quality Directive 2008/50/EC requires Member States to design appropriate air quality plans for zones where air quality does not comply with established limit values. However, in most cases, air quality is only quantified using a combination of monitored and modeled data and no health impact assessment is carried out. An integrated approach combining the effects of several emission abatement measures on air quality, impacts on human health, and associated implementation costs enables an effective cost-benefit analysis and an added value to the decision-making process. Hence, this review describes the basic steps and tools for integrating health into air quality assessment (health indicators, exposure-response functions). In addition, consideration is given to two major outdoor pollutants: PM and NO2. A summary of the health metrics used to assess the health impact of PM and NO2 and recent epidemiologic data are also described.

The Participation of Nitric Oxide in Peritoneal Exudate Cell Cytotoxicity of Mice byFusobacterium nucleatum

Previously we reported that mice infected recurrently with live Fusobacterium nucleatum(Fn) synthesize a significant amount of NO between 12 hr and 24 hr after Fn injection. Fn is a gram-negative rod periodontal pathogen. NO could not be induced by heat-killed Fn or in untreated mice. This NO, derived from the iNOS after infection of live Fn, was not involved in the Fn reduction because Fn clearance occurs within 6 hr. We investigated in this study whether this NO was involved in cytotoxicity in peritoneal exudate cells (PEC) in vivo. The mice were divided into two groups: those treated with live Fn (immune) and those left untreated (normal). PEC number, NO production, detection of apoptosis or death cells, and lactate dehydrogenase (LDH) release activity after injection of live Fn were compared in these groups. In the immune group, the increase of the total cell numbers caused by an increase in neutrophils, a significant NO production only after injection of live Fn at 24 hr and identification of iNOS positive macrophages were confirmed. The apoptotic rate was very low and did not increase at 24 hr in vivo. Therefore, apoptosis was seldom relevant to the NO. In the immune group, LDH activity was remarkable high at 24 hr, and dead cells and macrophages phagocytizing cell fragments increased at the same time. Pretreatment of L NMMA, an inhibitor of iNOS, suppressed LDH activity and cell death. Therefore, the NO derived from the iNOS is involved in the cytotoxicity. These results suggest that NO may contribute to the inflammatory response during Fn infection in periodontitis.

Nitric oxide modulates mitochondrial activity and apoptosis through protein S-nitrosylation for preimplantation embryo development

PURPOSE

Previous studies reported that patients with endometriosis had excess nitric oxide (NO) in the reproductive tract and poor embryo development in IVF cycles. This study aims to elucidate the effects of NO on early embryo development.

METHODS

Zygotes from superovulated B6CBF1 mice were cultured to blastocysts in a variety of media. Sodium nitroprusside (SNP) and N(G)-nitro-L-arginine (LNA) were added to the culture medium as a NO donor and a NO synthase inhibitor, respectively. The localization and fluorescence intensity of S-nitrosylated (SNO) proteins within 2-cell stage embryos were analyzed with confocal microscopy. Apoptosis and ATP production in the blastocysts were measured.

RESULT(S)

Subsequent to NO exposure, the SNO proteins mainly colocalized with the mitochondria and endoplasmic reticulum and the intensity of SNO proteins increased. The addition of a quanylate cyclase inhibitor and a cyclic GMP mimic agent induced nonsignificant changes in SNO proteins, whereas addition of a superoxide scavenger or a reduced form of glutathione rescued the embryos from the effects of NO. However, superoxide scavenger supplementation resulted in decreased blastocyst ATP production.

CONCLUSION(S)

Elevated NO exerts deleterious effects on embryo development, possibly through protein S-nitrosylation in the mitochondria and endoplasmic reticulum. Including glutathione as a component in the culture medium might counteract this effect.

DNA damage induced by nitric oxide during ionizing radiation is enhanced at replication

Nitric oxide (NO) is a very effective radiosensitizer of hypoxic mammalian cells, at least as efficient as oxygen in enhancing cell death in vitro. NO may induce cell death through the formation of base lesions which are difficult to repair, and if they occur within complex clustered damage common to ionizing radiation, they may lead to replication-induced DNA strand breaks. It has previously been shown that 8-azaguanine and xanthine result from the reaction of guanine radicals with nitric oxide. We have now shown that adenine radicals also react with NO to form hypoxanthine and 8-azaadenine. Cells irradiated in exponential growth in the presence of NO are twice as radiosensitive compared to those irradiated in anoxia alone, whereas confluent cells are less radiosensitive to (•)NO. In addition, the numbers of DNA double strand breaks observed as γH2AX staining following radiosensitization by NO, are higher in exponential cells than in confluent cells. DNA damage, detected as 53BP1 foci, is also higher in HF-19 cells expressing Cyclin A, a marker for cells in S and G2 phases of the cell cycle, following radiosensitization by NO. RAD51 foci are highest in V79-4 cells irradiated in the presence of NO compared to in anoxia, 24h after radiolysis. This work presents evidence that radiosensitization of cells by NO is in part through the formation of specific DNA damage, difficult to repair, which in dividing cells may induce the formation of stalled replication forks and as a consequence replication-induced DNA strand breaks which may lead to cell death.

Short-term effects of ambient particulates and gaseous pollutants on the incidence of transient ischaemic attack and minor stroke: a case-crossover study

BACKGROUND

While several studies have investigated the effects of short-term air pollution on cardiovascular disease, less is known about its effects on cerebrovascular disease, including stroke and transient ischaemic attack (TIA). The aim of the study was to assess the effects of short-term variation in air pollutants on the onset of TIA and minor stroke.

METHODS

We performed secondary analyses of data collected prospectively in the North West of England in a multi-centre study (NORTHSTAR) of patients with recent TIA or minor stroke. A case-crossover study was conducted to determine the association between occurrence of TIA and the concentration of ambient PM10 or gaseous pollutants.

RESULTS

A total of 709 cases were recruited from the Manchester (n = 335) and Liverpool (n = 374) areas. Data for the Manchester cohort showed an association between ambient nitric oxide (NO) and risk of occurrence of TIA and minor stroke with a lag of 3 days (odds ratio 1.06, 95% CI: 1.01 - 1.11), whereas negative association was found for the patients from Liverpool. Effects of similar magnitude, although not statistically significant, were generally observed with other pollutants. In a two pollutant model the effect of NO remained stronger and statistically significant when analysed in combination with CO or SO2, but was marginal in combination with NO2 or ozone and non-significant with PM10. There was evidence of effect modification by age, gender and season.

CONCLUSIONS

Our data suggest an association between NO and occurrence of TIA and minor stroke in Greater Manchester.

(-)-Epigallocatechin-3-gallate protects against NO-induced ototoxicity through the regulation of caspase- 1, caspase-3, and NF-κB activation

Excessive nitric oxide (NO) production is toxic to the cochlea and induces hearing loss. However, the mechanism through which NO induces ototoxicity has not been completely understood. The aim of this study was to gain further insight into the mechanism mediating NO-induced toxicity in auditory HEI-OC1 cells and in ex vivo analysis. We also elucidated whether and how epigallocatechin-3-gallate (EGCG), the main component of green tea polyphenols, regulates NO-induced auditory cell damage. To investigate NO-mediated ototoxicity, S-nitroso-N-acetylpenicillamine (SNAP) was used as an NO donor. SNAP was cytotoxic, generating reactive oxygen species, releasing cytochrome c, and activating caspase-3 in auditory cells. NO-induced ototoxicity also mediated the nuclear factor (NF)-κB/caspase-1 pathway. Furthermore, SNAP destroyed the orderly arrangement of the 3 outer rows of hair cells in the basal, middle, and apical turns of the organ of Corti from the cochlea of Sprague-Dawley rats at postnatal day 2. However, EGCG counteracted this ototoxicity by suppressing the activation of caspase-3/NF-κB and preventing the destruction of hair cell arrays in the organ of Corti. These findings may lead to the development of a model for pharmacological mechanism of EGCG and potential therapies against ototoxicity.

Does switching to a tobacco-free waterpipe product reduce toxicant intake? A crossover study comparing CO, NO, PAH, volatile aldehydes, "tar" and nicotine yields

Waterpipe (hookah, narghile, shisha) use has become a global phenomenon, with numerous product variations. One variation is a class of products marketed as "tobacco-free" alternatives for the "health conscious user". In this study toxicant yields from waterpipes smoked using conventional tobacco-based and tobacco-free preparations were compared. A human-mimic waterpipe smoking machine was used to replicate the puffing sequences of 31 human participants who completed two double-blind ad libitum smoking sessions in a controlled clinical setting: once with a tobacco-based product of their choosing and once with a flavor-matched tobacco-free product. Outcome measures included yields of carbon monoxide, nitric oxide, volatile aldehydes, nicotine, tar, and polycyclic aromatic hydrocarbons. Smoke from both waterpipe preparations contained substantial quantities of toxicants. Nicotine yield was the only outcome that differed significantly between preparations. These findings contradict advertising messages that "herbal" waterpipe products are a healthy alternative to tobacco products.

Kerosene: a review of household uses and their hazards in low- and middle-income countries

Kerosene has been an important household fuel since the mid-19th century. In developed countries its use has greatly declined because of electrification. However, in developing countries, kerosene use for cooking and lighting remains widespread. This review focuses on household kerosene uses, mainly in developing countries, their associated emissions, and their hazards. Kerosene is often advocated as a cleaner alternative to solid fuels, biomass and coal, for cooking, and kerosene lamps are frequently used when electricity is unavailable. Globally, an estimated 500 million households still use fuels, particularly kerosene, for lighting. However, there are few studies, study designs and quality are varied, and results are inconsistent. Well-documented kerosene hazards are poisonings, fires, and explosions. Less investigated are exposures to and risks from kerosene's combustion products. Some kerosene-using devices emit substantial amounts of fine particulates, carbon monoxide (CO), nitric oxides (NO(x)), and sulfur dioxide (SO(2)). Studies of kerosene used for cooking or lighting provide some evidence that emissions may impair lung function and increase infectious illness (including tuberculosis), asthma, and cancer risks. However, there are few study designs, quality is varied, and results are inconsistent. Considering the widespread use in the developing world of kerosene, the scarcity of adequate epidemiologic investigations, the potential for harm, and the implications for national energy policies, researchers are strongly encouraged to consider collecting data on household kerosene uses in studies of health in developing countries. Given the potential risks of kerosene, policymakers may consider alternatives to kerosene subsidies, such as shifting support to cleaner technologies for lighting and cooking.

An analysis of the respiratory health status among seafarers in the Russian trawler and merchant fleets

OBJECTIVES

Trawler fishermen and merchant seafarers have tough working conditions. While workers in both occupations are exposed to a challenging environment, trawler fishermen are also engaged in onboard fish processing, which is considered to be additional exposure. The aim of the present study was to characterize respiratory health status in both groups of seamen.

METHODS

In total 127 trawler fishermen and 118 merchant seafarers were enrolled during their regular medical health examinations. The study protocol comprised a standardized questionnaire, lung function test and measurements of fractional nitric oxide concentrations (FE(NO) ) in exhaled air.

RESULTS

Doctor-diagnosed asthma was reported only by trawler fishermen (3.9%, P < 0.05, Pearson Chi-square test). Adjusted odds ratios (OR) of respiratory symptoms were more often elevated in trawler fishermen compared to merchant seafarers. Trawler fishermen had reduced spirometric parameters: FEV(1) % of predicted values (adjusted β: -5.28, 95%CI: -9.28 to -1.27), FVC % of predicted values (adjusted β: -5.21, 95%CI: -9.25 to -1.17). Increased OR of the work-related cough with phlegm (OR: 6.6, 95% CI: 1.8-21.9), running nose (OR: 3.0, 95%CI: 1.2-7.7), and frequent sneezing (OR: 3.4, 95%CI: 1.0-12.7) were found among those trawler workers whose work tasks included filleting of fish. FE(NO) levels were not significantly different between trawler and merchant seamen.

CONCLUSIONS

The present study indicated that trawler fishermen exhibited impaired lung function and were more likely to have asthma. The environment of the onboard factories where fishermen fillet fish is suggested as a risk factor for work-related respiratory symptoms.

Effects of vehicle exhaust emissions on urban wild plant species

Very few investigations have examined the direct impacts of vehicle exhausts on plants and attempted to separate out the key pollutants responsible for observed effects. This paper describes a multi-phase investigation into this topic, using 12 herbaceous species typical of urban areas and representing different functional groups. Fumigations were conducted in solardomes with diesel exhaust pollutants at concentrations designed to simulate those close to a major highway in inner London. A wide range of effects were detected, including growth stimulation and inhibition, changes in gas exchange and premature leaf senescence. This was complemented by controlled fumigations with NO, NO(2) and their mixture, as well as a transect study away from a busy inner London road. All evidence suggested that NO(x) was the key phytotoxic component of exhaust emissions, and highlights the potential for detrimental effects of vehicle emissions on urban ecosystems.

Unravelling the pathway of respiratory toxicity in goldlined seabream (Rhabdosargus sarba) induced by the harmful alga Chattonella marina

The harmful alga Chattonella marina has caused massive fish kills and economic losses worldwide. Suffocation is generally believed to be the major cause of fish death by C. marina. However, the specific mechanisms leading to respiratory disorder in fish and subsequent fish kills by C. marina remain unknown. The goldlined seabream, highly susceptible to C. marina, was employed to investigate temporal changes of physiological, histopathological and biochemical parameters related to respiratory function at different stages of exposure to C. marina. Hemoglobin oxidation and blood lyses were not found in goldlined seabream exposed to C. marina, which could not be the key reasons accounting for pO(2) drop in the stressed fish. Gill histopathology such as irregular organization of lamellae, mucous with algal cells trapped in interfilamental spaces, were typical in C. marina exposed fish. A surge of plasma lactate occurred in goldlined seabream shortly after exposure to C. marina (0.5h) and sustained throughout the exposure period, indicating rapid onset of and persistent anaerobic respiration in C. marina exposed fish. Depletion of plasma glucose was clearly evident in goldlined seabream showing stress symptoms and near death. Yet, fish alive in the C. marina bloom did not exhibit plasma glucose depletion. The results suggest that availability of fermentable fuel as indicated by glucose level is critical to determine fish survival in C. marina exposure. Overall, our findings have rebuked the involvement of hemolysins and/or nitric oxide as the culprits for C. marina toxicity to fish. This study is the first to demonstrate the pathway of respiratory toxicity induced by the harmful alga C. marina in fish.

The use of fractional exhaled nitric oxide in investigation of work-related cough in a hairdresser

BACKGROUND

Occupational and environmental factors may be a cause of nonasthmatic eosinophilic bronchitis (NAEB). The diagnosis of occupational NAEB requires evidence of sputum eosinophilia. Nevertheless, a minority of patients are not able to produce suitable sputum specimens.

METHODS

This case report describes a 25-year-old woman, working as a hairdresser since the age of 20 years and handling ammonium persulfate, who came under our observation for work-related rhinitis and cough.

RESULTS

A specific inhalation challenge with ammonium persulfate elicited dry cough, without any significant change in forced expiratory volume in 1 s (FEV(1) ). Sputum induction was unsuccessful both pre- and after specific inhalation challenge. Fractional exhaled nitric oxide (FeNO) values significantly increased after specific inhalation challenge, suggesting a diagnosis of occupational NAEB due to ammonium persulfate.

CONCLUSIONS

From this observation we suggest that FeNO measurement should be added to the investigation of work-related cough during specific inhalation challenge, and may be considered as an alternative to induced sputum to evaluate bronchial inflammation when sputum collection is unavailable or unsuccessful.

Sickness response symptoms among healthy volunteers after controlled exposures to diesel exhaust and psychological stress

BACKGROUND

Interactions between acute exposures to environmental chemical contaminants and psychological stress may be important in situations where they are likely to co-occur, ranging in intensity from daily urban living to participation in war. Modification of symptomatic responses by stress may play a role in medically unexplained symptoms attributed to low-level chemical exposures.

OBJECTIVES

We hypothesized that the combination of exposure to diesel exhaust (DE) and acute psychological stress would cause sickness responses in healthy volunteers. Moreover, these responses would be greater in individuals with self-reported prior chemical odor intolerance.

METHODS

One hundred adult subjects underwent 1-hr exposures to diluted DE and clean air control. Half of the subjects performed a public-speaking stressor task during the exposures. Subjects completed questionnaires to determine their Chemical Odor Intolerance Index score. Plasma cortisol, end-tidal carbon dioxide, and the severity of 35 symptoms were measured at time points before and after the exposures.

RESULTS

Subjects exposed to DE demonstrated small but statistically significant increases in severity for several symptom categories, including sickness response and upper respiratory, central nervous system, and total symptoms. The psychological stressor did not increase symptom severity independently or via interaction with DE. Subjects with prior self-reported chemical intolerance had more severe sickness response symptoms from DE.

CONCLUSIONS

These results suggest that exposure to DE can cause acute sickness response symptoms and that these symptoms are also associated with increased levels of self-reported chemical intolerance. The results did not confirm our hypothesis that an acute stressor would increase sickness response symptom severity during the exposure.

Part 3. Estimating the effects of air pollution on mortality in Bangkok, Thailand

While the effects of particulate matter (PM*) on mortality have been well documented in North America and Western Europe, considerably less is known about its effects in developing countries in Asia. Existing air pollution data in Bangkok, Thailand, indicate that airborne concentrations of PM < or = 10 pm in aerodynamic diameter (PM10) are as high or higher than those experienced in most cities in North America and Western Europe. At the same time, the demographics, activity patterns, and background health status of the population, as well as the chemical composition of PM, are different in Bangkok. It is important, therefore, to determine whether the effects of PM10 on mortality occurring in this large metropolitan area are similar to those in Western cities. The quality and completeness of Bangkok mortality data have been recently enhanced by the completion of a few mortality studies and through input from monitors currently measuring daily PM10 in Bangkok. In this analysis, we examined the effects of PM10 and several gaseous pollutants on daily mortality for the years 1999 through 2003. Our results suggest strong associations between several different mortality outcomes and levels of PM10 and several of the gaseous pollutants, including nitrogen dioxide (NO2), nitric oxide (NO), and ozone (O3). In many cases, the effect estimates were higher than the approximately 6% per 10 microg/m3 typically reported in Western industrialized nations-based on reviews by the U.S. Environmental Protection Agency (U.S. EPA) and the World Health Organization (WHO) (Anderson et al. 2004). For example, the excess risk (ER) for mortality due to all natural causes was 1.3% (95% confidence interval [CI], 0.8 to 1.7), with higher ERs for cardiovascular and respiratory mortality of 1.9% (95% CI, 0.8 to 3.0) and 1.0% (95% CI, -0.4 to 2.4), respectively. Of particular note, for this warm, tropical city of approximately 6 to 10 million people, is that there is no covariation between pollution and cold weather, with its associated adverse health problems. Multiday averages of PM10 generated even higher effect estimates. Our analysis of age- and disease-specific mortality indicated elevated ERs for young children, especially infants with respiratory illnesses, children less than 5 years of age with lower respiratory infections (LRIs), and people with asthma. Age-restricted analyses showed that the associations between mortality due to all natural causes and PM10 concentration increased with age, with the strongest effects among people aged 75 years and older. However, associations between increases in PM10 concentration and mortality were observed for all of the other age groups. With a few exceptions, relatively similar results were observed for several of the other pollutants-sulfur dioxide (SO2), NO2, O3, and NO, which were highly correlated with PM10. However, many of the effects from gaseous pollutants were attenuated in multipollutant models, while effects from PM10 appeared to be most consistent. In addition, there was some evidence of an independent effect of O3 for certain health outcomes. We conducted substantial sensitivity analyses to examine whether our results were robust. The results indicated that our core model was generally robust to the choice of model specification, spline model, degrees of freedom (df) of time-smoothing functions, lags for temperature, adjustment for autocorrelation, adjustment for epidemics, and adjustment for missing values using centered data (see the description of the centering method used in the Common Protocol found at the end of this volume). Finally, the concentration-response functions for most of the pollutants appear to be linear. Thus, our sensitivity analyses results suggest an impact of pollution on mortality in Bangkok that is fairly consistent. They also provide support for the extrapolation of results from health effects studies conducted in North America and Western Europe to other parts of the world, including developing countries in Asia.

Vibrio fischeri flavohaemoglobin protects against nitric oxide during initiation of the squid-Vibrio symbiosis

Nitric oxide (NO) is implicated in a wide range of biological processes, including innate immunity against pathogens, signal transduction and protection against oxidative stress. However, its possible roles in beneficial host-microbe associations are less well recognized. During the early stages of the squid-vibrio symbiosis, the bacterial symbiont Vibrio fischeri encounters host-derived NO, which has been hypothesized to serve as a specificity determinant. We demonstrate here that the flavohaemoglobin, Hmp, of V. fischeri protects against NO, both in culture and during colonization of the squid host. Transcriptional analyses indicate that hmp expression is highly responsive to NO, principally through the repressor, NsrR. Hmp protects V. fischeri from NO inhibition of aerobic respiration, and removes NO under both oxic and anoxic conditions. A Δhmp mutant of V. fischeri initiates squid colonization less effectively than wild type, but is rescued by the presence of an NO synthase inhibitor. The hmp promoter is activated during the initial stage of colonization, during which the Δhmp strain fails to form normal-sized aggregates of colonizing cells. Taken together, these results suggest that the sensing of host-derived NO by NsrR, and the subsequent removal of NO by Hmp, influence aggregate size and, thereby, V. fischeri colonization efficiency.

Cell type specificity of lung cancer associated with nitric oxide

We aimed to explore whether lung cancer associated with air pollutants, specifically nitric oxide (NO), has cell type specificity. Both Spearman correlation and multiple linear regression between the air quality indices (SO(2), CO, O(3), NO, and NO(2)) and age-standardized incidence rate (ASR) of lung cancer by two major pathological types were calculated for both genders. We conducted 4 levels of analyses based on different NO concentrations. We also used Poisson regression to estimate the relative risk of lung cancer. Regardless of gender, the influences of SO(2), CO, O(3), and NO(2) were not statistically significant. There was a dose-response relationship between NO concentrations and adenocarcinoma (AC) incidence rates. On the other hand, none of the air pollutants had a significant impact on the squamous cell carcinoma (SCC) incidence rates for both males and females. The Poisson regression results showed that with the NO concentration < or = 5.59 ppb as the baseline, the risk for AC among males at 5.59 < NO < or = 8.55 ppb was 1.32 times of that at the baseline level (95% CI, 1.11-1.59), 1.33 times at 8.55 < NO < or = 13.54 ppb (95% CI, 1.11-1.61), 1.66 times when NO > 13.54 ppb (95% CI, 1.36-2.01). The test for trend was statistically significant at P<0.001. Similar results were observed among females. On the contrary, for SCC, we found NO did not pose any significant danger to males and females.

CONCLUSION

Our results showed that there was a dose-response relationship between gaseous NO concentrations and lung AC incidence rates.

A comparison of vascular effects from complex and individual air pollutants indicates a role for monoxide gases and volatile hydrocarbons

BACKGROUND

Emerging evidence suggests that the systemic vasculature may be a target of inhaled pollutants of vehicular origin. We have identified several murine markers of vascular toxicity that appear sensitive to inhalation exposures to combustion emissions.

OBJECTIVE

We sought to examine the relative impact of various pollutant atmospheres and specific individual components on these markers of altered vascular transcription and lipid peroxidation.

METHODS

Apolipoprotein E knockout (ApoE(-/-)) mice were exposed to whole combustion emissions (gasoline, diesel, coal, hardwood), biogenically derived secondary organic aerosols (SOAs), or prominent combustion-source gases [nitric oxide (NO), NO(2), carbon monoxide (CO)] for 6 hr/day for 7 days. Aortas were assayed for transcriptional alterations of endothelin-1 (ET-1), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-2 (TIMP-2), and heme oxygenase-1 (HO-1), along with measures of vascular lipid peroxides (LPOs) and gelatinase activity.

RESULTS

We noted transcriptional alterations with exposures to gasoline and diesel emissions. Interestingly, ET-1 and MMP-9 transcriptional effects could be recreated by exposure to CO and NO, but not NO(2) or SOAs. Gelatinase activity aligned with levels of volatile hydrocarbons and also monoxide gases. Neither gases nor particles induced vascular LPO despite potent effects from whole vehicular emissions.

CONCLUSIONS

In this head-to-head comparison of the effects of several pollutants and pollutant mixtures, we found an important contribution to vascular toxicity from readily bioavailable monoxide gases and possibly from volatile hydrocarbons. These data support a role for traffic-related pollutants in driving cardiopulmonary morbidity and mortality.

Impact of improved air quality during the 1996 Summer Olympic Games in Atlanta on multiple cardiovascular and respiratory outcomes

Substantial evidence supports an association between ambient air pollution, especially particulate matter (PM*) and ozone (O3), and acute cardiovascular and respiratory morbidity. There is increasing interest in accountability research to evaluate whether actions taken to reduce air pollution will result in reduced morbidity. This study capitalized on a unique opportunity to evaluate the impact of a local, short-term intervention effort to reduce traffic in Atlanta during the 1996 Summer Olympic Games (July 19-August 4). Air pollutant concentrations both inside and outside of Atlanta were examined during the Olympic period and surrounding periods. Emergency department (ED) visits were examined to evaluate changes in usage patterns. ED visits for respiratory and cardiovascular conditions were examined in relation to the Olympic period using Poisson time-series analysis with adjustment for time trends and meteorologic conditions. O3 concentrations were approximately 30% lower during the Olympic Games compared with the four weeks before and after the Olympic Games (baseline periods); however, we observed similar reductions in O3 concentrations in several other cities in the Southeastern United States. We observed little or no evidence of reduced ED visits during the Olympic Games; the estimates were sensitive to choice of analytic model and to method of adjusting for temporal trends. The meteorologic conditions during the Olympic Games, along with the reductions in O3 observed in various cities not impacted by the Olympic Games, suggest that both meteorologic conditions-and reduced traffic may have played a role in the observed reduction in O3 concentration in Atlanta. Additionally, it is likely that this particular intervention strategy would not be sustainable as a pollution-reduction strategy. This study demonstrates some limitations of conducting retrospective accountability research.

Nitric oxide mediated DNA double strand breaks induced in proliferating bystander cells after alpha-particle irradiation

Low-dose alpha-particle exposures comprise 55% of the environmental dose to the human population and have been shown to induce bystander responses. Previous studies showed that bystander effect could induce stimulated cell growth or genotoxicity, such as excessive DNA double strand breaks (DSBs), micronuclei (MN), mutation and decreased cell viability, in the bystander cell population. In the present study, the stimulated cell growth, detected with flow cytometry (FCM), and the increased MN and DSB, detected with p53 binding protein 1 (53BP1) immunofluorescence, were observed simultaneously in the bystander cell population, which were co-cultured with cells irradiated by low-dose alpha-particles (1-10 cGy) in a mixed system. Further studies indicated that nitric oxide (NO) and transforming growth factor beta1 (TGF-beta1) played very important roles in mediating cell proliferation and inducing MN and DSB in the bystander population through treatments with NO scavenger and TGF-beta1 antibody. Low-concentrations of NO, generated by spermidine, were proved to induce cell proliferation, DSB and MN simultaneously. The proliferation or shortened cell cycle in bystander cells gave them insufficient time to repair DSBs. The increased cell division might increase the probability of carcinogenesis in bystander cells since cell proliferation increased the probability of mutation from the mis-repaired or un-repaired DSBs.

Different toxic effects of hydrogen peroxide, nitric oxide, and superoxide on human, pig, and rat islets of Langerhans

Susceptibility of islet cells to damage by hydrogen peroxide, superoxide, and nitric oxide was determined on islets isolated from humans, pigs, and rats. Islets were incubated for 20 hr at 37 degrees C with different concentrations of hydrogen peroxide, hypoxanthine/xanthine oxidase, or nitroprusside sodium, respectively. Islet cell damage was then measured as trypan blue-uptake. Rat islets showed a higher sensitivity than human or pig islets to damage by reactive oxygen species or nitric oxide. These results indicate that pig islets may be a more suitable model than rat islets to study inflammatory islet cell damage in diabetes and clinical islet transplantation.

Alteration of nitric oxide gas on gene expression of endothelin-1 and endothelial nitric oxide synthase by a time- and dose-dependent manner in human endothelial cells

Our purpose was to investigate the gene expression of endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVECs) under various concentrations and periods of exogenous nitric oxide (NO) gas exposure. Cultured HUVECs were exposed to 0, 20, and 80 ppm NO for 0, 24, and 48 h. With NO exposure for 24 h, ET-1 peptide levels decreased in both the 20 and 80 ppm groups. Thereafter, at 48 h, ET-1 peptide levels persistently decreased in the 20 ppm group, but significantly increased in the 80 ppm group. Furthermore, there was a significant decrease in the expression levels of eNOS protein and mRNA in the 80 ppm 48 h group. The data suggest a time- and dose-dependent effect of NO gas exposure on the gene expression of ET-1 and eNOS in HUVECs. A high concentration and long period of NO exposure induces an inhibition of eNOS and enhancement of ET-1, which could lead to vasoconstriction. These findings may have clinical implications in NO therapy regarding the optimal dose and period.

Differential sensitivity of oligodendrocytes and motor neurons to reactive nitrogen species: implications for multiple sclerosis

Depending on its concentration, nitric oxide (NO) has beneficial or toxic effects. In pathological conditions, NO reacts with superoxide to form peroxynitrite, which nitrates proteins forming nitrotyrosine residues (3NY), leading to loss of protein function, perturbation of signal transduction, and cell death. 3NY immunoreactivity is present in many CNS diseases, particularly multiple sclerosis. Here, using the high flux NO donor, spermine-NONOate, we report that oligodendrocytes are resistant to NO, while motor neurons are NO sensitive. Motor neuron sensitivity correlates with the NO-dependent formation of 3NY, which is significantly more pronounced in motor neurons when compared with oligodendrocytes, suggesting peroxynitrite as the toxic molecule. The heme-metabolizing enzyme, heme-oxygenase-1 (HO1), is necessary for oligodendrocyte NO resistance, as demonstrated by loss of resistance after HO1 inhibition. Resistance is reinstated by peroxynitrite scavenging with uric acid further implicating peroxynitrite as responsible for NO sensitivity. Most importantly, differential sensitivity to NO is also present in cultures of primary oligodendrocytes and motor neurons. Finally, motor neurons cocultured with oligodendrocytes, or oligodendrocyte-conditioned media, become resistant to NO toxicity. Preliminary studies suggest oligodendrocytes release a soluble factor that protects motor neurons. Our findings challenge the current paradigm that oligodendrocytes are the exclusive target of multiple sclerosis pathology.

Reactive oxygen species- and nitric oxide-mediated lung inflammation and mitochondrial dysfunction in wild-type and iNOS-deficient mice exposed to diesel exhaust particles

Pulmonary responses to diesel exhaust particles (DEP) exposure are mediated through enhanced production of reactive oxygen species (ROS) and nitric oxide (NO) by alveolar macrophages (AM). The current study examined the differential roles of ROS and NO in DEP-induced lung injury using C57B/6J wild-type (WT) and inducible NO synthase knockout (iNOS KO) mice. Mice exposed by pharyngeal aspiration to DEP or carbon black particles (CB) (35 mg/kg) showed an inflammatory profile that included neutrophil infiltration, increased lactate dehydrogenase (LDH) activity, and elevated albumin content in bronchoalveolar lavage fluid (BALF) at 1, 3, and 7 d postexposure. The organic extract of DEP (DEPE) did not induce an inflammatory response. Comparing WT to iNOS KO mice, the results show that NO enhanced DEP-induced neutrophils infiltration and plasma albumin content in BALF and upregulated the production of the pro-inflammatory cytokine interleukin 12 (IL-12) by AM. DEP-exposed AM from iNOS KO mice displayed diminished production of IL-12 and, in response to ex vivo lipopolysaccharide (LPS) challenge, decreased production of IL-12 but increased production of IL-10 when compared to cells from WT mice. DEP, CB, but not DEPE, induced DNA damage and mitochondria dysfunction in AM, however, that is independent of cellular production of NO. These results demonstrate that DEP-induced immune/inflammatory responses in mice are regulated by both ROS- and NO-mediated pathways. NO did not affect ROS-mediated mitochondrial dysfunction and DNA damage but upregulated IL-12 and provided a counterbalance to the ROS-mediated adaptive stress response that downregulates IL-12 and upregulates IL-10.

Virulence of Mycobacterium avium in mice does not correlate with resistance to nitric oxide

The growth in C57Bl/6 mice of seven distinct Mycobacterium avium strains was not exacerbated by the disruption of the inducible (type 2) nitric oxide synthase regardless of the virulence of the strain. The susceptibility of this panel of M. avium strains to reactive nitrogen intermediates in a cell-free system, namely the exposure to acidified nitrite or to the NO donor NOC-18, showed that there is no correlation between strain virulence and the corresponding minimal bactericidal and minimal inhibitory concentrations for those compounds determined in vitro.

A novel mechanism underlying the susceptibility of neuronal cells to nitric oxide: the occurrence and regulation of protein S-nitrosylation is the checkpoint

The susceptibility of neuronal cells to nitric oxide (NO) is a key issue in NO-mediated neurotoxicity. However, the underlying mechanism remains unclear. As a cyclic guanosine monophosphate (cGMP)-independent NO signaling pathway, S-nitrosylation (or S-nitrosation) has been suggested to occur as a post-translational modification in parallel with O-phosphorylation. The underlying mechanism of the involvement of protein S-nitrosylation in the susceptibility of neuronal cells to NO has been little investigated. In this study, we focused on the role of S-nitrosothiols (RSNO) in the susceptibility of a cerebellar cell line R2 to NO. Our results showed the following: (i) S-nitrosoglutathione (GSNO) induced a burst of RSNO in GSH-depleted R2 cells, the majority of which were primarily contributed by the S-nitrosylation of proteins (Pro-SNOs), and was followed by severe neuronal necrosis; (ii) the elevation in the level of Pro-SNOs resulted from a dysfunction of S-nitroglutathione reductase (GSNOR) as a result of its substrate, GSNO, being unavailable in GSH-depleted cells. In the meantime, the suppression of GSNOR increased NO-mediated neurotoxicity in R2 cells, as well as in cerebellar granule neurons; (iii) Our results also demonstrate that the burst of RSNO is the "checkpoint" of cell fate: if RSNO can be reduced to free thiol proteins, cells will survive; if they are further oxidized, cells will die; and (iv) GSH-ethyl ester and Vitamin C protected R2 cells against GSNO neurotoxicity through two distinct mechanisms: by inhibiting the elevation of Pro-SNOs and by reducing Pro-SNOs to free thiol proteins, respectively. A novel mechanism underlying the susceptibility of neuronal cells to NO is proposed and some potential strategies to prevent the NO-mediated neurotoxicity are discussed.

Nitric oxide in the central nervous system: neuroprotection versus neurotoxicity

At the end of the 1980s, it was clearly demonstrated that cells produce nitric oxide and that this gaseous molecule is involved in the regulation of the cardiovascular, immune and nervous systems, rather than simply being a toxic pollutant. In the CNS, nitric oxide has an array of functions, such as the regulation of synaptic plasticity, the sleep-wake cycle and hormone secretion. Particularly interesting is the role of nitric oxide as a Janus molecule in the cell death or survival mechanisms in brain cells. In fact, physiological amounts of this gas are neuroprotective, whereas higher concentrations are clearly neurotoxic.