Gold(I) ion and the phosphine ligand are necessary for the anti-Toxoplasma gondii activity of auranofin

Auranofin, an FDA-approved drug for rheumatoid arthritis, has emerged as a promising antiparasitic medication in recent years. The gold(I) ion in auranofin is postulated to be responsible for its antiparasitic activity. Notably, aurothiomalate and aurothioglucose also contain gold(I), and, like auranofin, they were previously used to treat rheumatoid arthritis. Whether they have antiparasitic activity remains to be elucidated. Herein, we demonstrated that auranofin and similar derivatives, but not aurothiomalate and aurothioglucose, inhibited the growth of Toxoplasma gondii in vitro. We found that auranofin affected the T. gondii biological cycle (lytic cycle) by inhibiting T. gondii's invasion and triggering its egress from the host cell. However, auranofin could not prevent parasite replication once T. gondii resided within the host. Auranofin treatment induced apoptosis in T. gondii parasites, as demonstrated by its reduced size and elevated phosphatidylserine externalization (PS). Notably, the gold from auranofin enters the cytoplasm of T. gondii, as demonstrated by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).IMPORTANCEToxoplasmosis, caused by Toxoplasma gondii, is a devastating disease affecting the brain and the eyes, frequently affecting immunocompromised individuals. Approximately 60 million people in the United States are already infected with T. gondii, representing a population at-risk of developing toxoplasmosis. Recent advances in treating cancer, autoimmune diseases, and organ transplants have contributed to this at-risk population's exponential growth. Paradoxically, treatments for toxoplasmosis have remained the same for more than 60 years, relying on medications well-known for their bone marrow toxicity and allergic reactions. Discovering new therapies is a priority, and repurposing FDA-approved drugs is an alternative approach to speed up drug discovery. Herein, we report the effect of auranofin, an FDA-approved drug, on the biological cycle of T. gondii and how both the phosphine ligand and the gold molecule determine the anti-parasitic activity of auranofin and other gold compounds. Our studies would contribute to the pipeline of candidate anti-T. gondii agents.

Chemical and Cellular Formation of Reactive Oxygen Species from Secondary Organic Aerosols in Epithelial Lining Fluid

INTRODUCTION

Oxidative stress mediated by reactive oxygen species (ROS) is a key process for adverse aerosol health effects. Secondary organic aerosols (SOA) account for a major fraction of particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5). PM2.5 inhalation and deposition into the respiratory tract causes the formation of ROS by chemical reactions and phagocytosis of macrophages in the epithelial lining fluid (ELF), but their relative contributions are not well quantified and their link to oxidative stress remains uncertain. The specific aims of this project were (1) elucidating the chemical mechanism and quantifying the formation kinetics of ROS in the ELF by SOA; (2) quantifying the relative importance of ROS formation by chemical reactions and macrophages in the ELF.

METHODS

SOA particles were generated using reaction chambers from oxidation of various precursors including isoprene, terpenes, and aromatic compounds with or without nitrogen oxides (NOx). We collected size-segregated PM at two highway sites in Anaheim, CA, and Long Beach, CA, and at an urban site in Irvine, CA, during two wildfire events. The collected particles were extracted into water or surrogate ELF that contained lung antioxidants. ROS generation was quantified using electron paramagnetic resonance (EPR) spectroscopy with a spin-trapping technique. PM oxidative potential (OP) was also quantified using the dithiothreitol assay. In addition, kinetic modeling was applied for analysis and interpretation of experimental data. Finally, we quantified cellular superoxide release by RAW264.7 macrophage cells upon exposure to quinones and isoprene SOA using a chemiluminescence assay as calibrated with an EPR spin-probing technique. We also applied cellular imaging techniques to study the cellular mechanism of superoxide release and oxidative damage on cell membranes.

RESULTS

Superoxide radicals (·O2-) were formed from aqueous reactions of biogenic SOA generated by hydroxy radical (·OH) photooxidation of isoprene, β-pinene, α-terpineol, and d-limonene. The temporal evolution of ·OH and ·O2- formation was elucidated by kinetic modeling with a cascade of aqueous reactions, including the decomposition of organic hydroperoxides (ROOH), ·OH oxidation of primary or secondary alcohols, and unimolecular decomposition of α-hydroxyperoxyl radicals. Relative yields of various types of ROS reflected the relative abundance of ROOH and alcohols contained in SOA, which generated under high NOx conditions, exhibited lower ROS yields. ROS formation by SOA was also affected by pH. Isoprene SOA had higher ·OH and organic radical yields at neutral than at acidic pH. At low pH ·O2- was the dominant species generated by all types of SOA. At neutral pH, α-terpineol SOA exhibited a substantial yield of carbon-centered organic radicals (R·), while no radical formation was observed by aromatic SOA.

Organic radicals in the ELF were formed by mixtures of Fe2+ and SOA generated from photooxidation of isoprene, α-terpineol, and toluene. The molar yields of organic radicals by SOA were 5-10 times higher in ELF than in water. Fe2+ enhanced organic radical yields by a factor of 20-80. Ascorbate mediated redox cycling of iron ions and sustained organic peroxide decomposition, as supported by kinetic modeling reproducing time- and concentration-dependence of organic radical formation, as well as by additional experiments observing the formation of Fe2+ and ascorbate radicals in mixtures of ascorbate and Fe3+. ·OH and superoxide were found to be efficiently scavenged by antioxidants.

Wildfire PM mainly generated ·OH and R· with minor contributions from superoxide and oxygen-centered organic radicals (RO·). PM OP was high in wildfire PM, exhibiting very weak correlation with radical forms of ROS. These results were in stark contrast with PM collected at highway and urban sites, which generated much higher amounts of radicals dominated by ·OH radicals that correlated well with OP. By combining field measurements of size-segregated chemical composition, a human respiratory tract model, and kinetic modeling, we quantified production rates and concentrations of different types of ROS in different regions of the ELF by considering particle-size-dependent respiratory deposition. While hydrogen peroxide (H2O2) and ·O2- production were governed by Fe and Cu ions, ·OH radicals were mainly generated by organic compounds and Fenton-like reactions of metal ions. We obtained mixed results for correlations between PM OP and ROS formation, providing rationale and limitations of the use of oxidative potential as an indicator for PM toxicity in epidemiological and toxicological studies.

Quinones and isoprene SOA activated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in macrophages, releasing massive amounts of superoxide via respiratory burst and overwhelming the superoxide formation by aqueous chemical reactions in the ELF. The threshold dose for macrophage activation was much smaller for quinones compared with isoprene SOA. The released ROS caused lipid peroxidation to increase cell membrane fluidity, inducing oxidative damage and stress. Further increases of doses led to the activation of antioxidant response elements, reducing the net cellular superoxide production. At very high doses and long exposure times, chemical production became comparably important or dominant if the escalation of oxidative stress led to cell death.

CONCLUSIONS

The mechanistic understandings and quantitative information on ROS generation by SOA particles provided a basis for further elucidation of adverse aerosol health effects and oxidative stress by PM2.5. For a comprehensive assessment of PM toxicity and health effects via oxidative stress, it is important to consider both chemical reactions and cellular processes for the formation of ROS in the ELF. Chemical composition of PM strongly influences ROS formation; further investigations are required to study ROS formation from various PM sources. Such research will provide critical information to environmental agencies and policymakers for the development of air quality policy and regulation.

Proteomic changes driven by urban pollution suggest particulate matter as a deregulator of energy metabolism, mitochondrial activity, and oxidative pathways in the rat brain

The adverse effects of air pollution have been long studied in the lung and respiratory systems, but the molecular changes that this causes at the central nervous system level have yet to be fully investigated and understood. To explore the evolution with time of protein expression levels in the brain of rats exposed to particulate matter of different sizes, we carried out two-dimensional gel electrophoresis followed by determination of dysregulated proteins through Coomassie blue staining-based densities (SameSpots software) and subsequent protein identification using MALDI-based mass spectrometry. Expression differences in dysregulated proteins were found to be statistically significant with p-value <0.05. A systems biology-based approach was utilized to determine critical biochemical pathways involved in the rats' brain response. Our results suggest that rats' brains have a particulate matter size dependent-response, being the mitochondrial activity and the astrocyte function severely affected. Our proteomic study confirms the dysregulation of different biochemical pathways involving energy metabolism, mitochondrial activity, and oxidative pathways as some of the main effects of PM exposure on the rat brain. SIGNIFICANCE: Rat brains exposed to particulate matter with origin in car engines are affected in two main areas: mitochondrial activity, by the dysregulation of many pathways linked to the respiratory chain, and neuronal and astrocytic function, which stimulates brain changes triggering tumorigenesis and neurodegeneration.

Exposure to ambient particulate matter induces oxidative stress in lung and aorta in a size- and time-dependent manner in rats

Exposure to particulate matter (PM) has been implicated in oxidative stress (OxS) and inflammation as underlying mechanisms of lung damage and cardiovascular alterations. PM is a chemical mixture that can be subdivided according to their aerodynamic size into coarse (CP), fine (FP), and ultrafine (UFP) particulates. We investigated, in a rat model, the induction of OxS (protein oxidation and antioxidant response), carcinogen-DNA adduct formation, and inflammatory mediators in lung in response to different airborne particulate fractions, CP, FP, and UFP, after an acute and subchronic exposure. In addition, OxS was evaluated in the aorta to assess the effects beyond the lungs. Exposure to CP, FP, and UFP induced time- and size-dependent lung protein oxidation and DNA adduct formation. After acute and subchronic exposure, nuclear factor erythroid-2 (Nrf2) activation was observed in the lung, by electrophoretic mobility shift assay, and the induction of mRNA antioxidant enzymes in the FP and UFP groups, but not in the CP. Cytokine concentration of interleukin 1β, interleukin 6, and macrophage inflammatory protein-2 was significantly increased in bronchoalveolar lavage fluid after acute exposure to FP and UFP. Activation of Nrf2 and expression of mRNA antioxidant enzymes were observed only after the subchronic exposure to FP and UFP in the aorta. Our results indicate that FP and UFP were mainly accountable for the oxidant toxic effects in the lung; OxS is spread from the lung to the cardiovascular system. We conclude that the biological mechanisms associated with transient OxS and inflammation are particle size and time-dependent exposure resulting in acute lung injury, which later reaches the vascular system.

Phosphorylation of a constrained azacyclic FTY720 analog enhances anti-leukemic activity without inducing S1P receptor activation

The frequency of poor outcomes in relapsed leukemia patients underscores the need for novel therapeutic approaches. The FDA-approved immunosuppressant FTY720 limits leukemia progression by activating protein phosphatase 2A and restricting nutrient access. Unfortunately, FTY720 cannot be re-purposed for use in cancer patients due to on-target toxicity associated with S1P receptor activation at the elevated, anti-neoplastic dose. Here we show that the constrained azacyclic FTY720 analog SH-RF-177 lacks S1P receptor activity but maintains anti-leukemic activity in vitro and in vivo. SH-RF-177 was not only more potent than FTY720, but killed via a distinct mechanism. Phosphorylation is dispensable for FTY720’s anti-leukemic actions. However, chemical biology and genetic approaches demonstrated that the sphingosine kinase 2- (SPHK2) mediated phosphorylation of SH-RF-177 led to engagement of a pro-apoptotic target and increased potency. The cytotoxicity of membrane-permeant FTY720 phosphonate esters suggests that the enhanced potency of SH-RF-177 stems from its more efficient phosphorylation. The tight inverse correlation between SH-RF-177 IC₅₀ and SPHK2 mRNA expression suggests a useful biomarker for SH-RF-177 sensitivity. In summary, these studies indicate that FTY720 analogs that are efficiently phosphorylated but fail to activate S1P receptors may be superior anti-leukemic agents compared to compounds that avoid cardiotoxicity by eliminating phosphorylation.

Nitrogen dioxide and ozone as factors in the availability of lead from lead-based paints

Lead-based paint remains a pervasive problem in U.S. cities, and an increasing problem in the developing world where it is still manufactured and used. Little attention has focused on the factors that increase the release of lead pigment granules from painted surfaces. Nitrogen dioxide (NO(2)) and ozone (O(3)) from transportation emissions in urban environments have the potential to react with and remove polymeric binders in paint, making pigment granules more available for subsequent transfer to hands on contact, or deposition in housedust. Here we show that exposure to NO(2) and O(3) increased the lead in wipe samples of stainless steel surfaces painted with alkyd low gloss solvent lead-based paint by 296% +/- 101 (or 0.24 microg/cm(2)) and 37% +/- 21 (or 0.025 microg/cm(2)), respectively, with corresponding changes in surface morphology indicated by reflectometry and scanning electron microscopy. Lead release from unexposed low gloss acrylic household paints was 40 times greater than comparable solvent based paints. Given that lead-based paint is still manufactured and used in many urban areas of the developing world where O(3) concentrations currently exceed historic U.S. concentrations, the interaction of air pollution with lead painted indoor surfaces may pose greater exposure risks for lead poisoning in children than previously anticipated.

Inhaled ultrafine particulate matter affects CNS inflammatory processes and may act via MAP kinase signaling pathways

In addition to evidence that inhalation of ambient particulate matter (PM) can increase cardiopulmonary morbidity and mortality, the brain may also constitute a site adversely effected by the environmental presence of airborne particulate matter. We have examined the association between exposure to PM and adverse CNS effects in apolipoprotein E knockout (ApoE-/-) mice exposed to two levels of concentrated ultrafine particulate matter in central Los Angeles. Mice were euthanized 24h after the last exposure and brain, liver, heart, lung and spleen tissues were collected and frozen for subsequent bioassays. There was clear evidence of aberrant immune activation in the brains of exposed animals as judged by a dose-related increase in nuclear translocation of two key transcription factors, NF-kappaB and AP-1. These factors are involved in the promotion of inflammation. Increased levels of glial fibrillary acidic protein (GFAP) were also found consequent to particulate inhalation suggesting that glial activation was taking place. In order to determine the mechanism by which these events occurred, levels of several MAP kinases involved in activation of these transcription factors were assayed by Western blotting. There were no significant changes in the proportion of active (phosphorylated) forms of ERK-1, IkB and p38. However, the fraction of JNK in the active form was significantly increased in animals receiving the lower concentration of concentrated ambient particles (CAPs). This suggests that the signaling pathway by which these transcription factors are activated involves the activation of JNK.

Effect of cigarette smoking on nitric oxide, structural, and mechanical properties of mouse arteries

Cigarette smoking (CS) is a major risk factor for vascular disease. The aim of this study was to quantitatively assess the influence of CS on mouse arteries. We studied the effect of short-term (6 wk) and long-term (16 wk) CS exposure on structural and mechanical properties of coronary arteries compared with that of control mice. We also examined the reversibility of the deleterious effects of CS on structural [e.g., wall thickness (WT)], mechanical (e.g., stiffness), and biochemical [e.g., nitric oxide (NO) by-products] properties with the cessation of CS. The left and right coronary arteries were cannulated in situ and mechanically distended. The stress, strain, elastic modulus, and WT of coronary arteries were determined. Western blot analysis was used to analyze endothelial NO synthase (eNOS) in the femoral and carotid arteries of the same mice, and NO by-products were determined by measuring the levels of nitrite. Our results show that the mean arterial pressure was increased by CS. Furthermore, CS significantly increased the elastic modulus, decreased stress and strain, and increased the WT and WT-to-radius ratio compared with those of control mice. The reduction of eNOS protein expression was found only after long-term CS exposure. Moreover, the NO metabolite was markedly decreased in CS mice after short- and long-term exposure of CS. These findings suggest that 16 wk of CS exposure can cause an irreversible deterioration of structural and elastic properties of mouse coronary arteries. The decrease in endothelium-derived NO in CS mice was seen to significantly correlate with the remodeling of arterial wall.

Pb enamel biomarker: deposition of pre- and postnatal Pb isotope injection in reconstructed time points along rat enamel transect

Exposure to lead (Pb) as well as other heavy metals in the environment is still a matter of public health concern. The development of the enamel biomarker for heavy metal exposure assessment is designed to improve studies of dose-effect relationships to developmental anomalies, particularly embryonic dysfunctions, and to provide a time-specific recount of past exposures. The work presented in this paper demonstrates maternal transfer across the placental barrier of the enriched isotope (206)Pb tracer to the enamel of the rat pup. Likewise, injections of (204)Pb-enriched tracer in the neonate rat resulted in deposition of the tracer in the enamel histology as measured by secondary ion microprobe spectrometry. Through enamel, we were able to observe biological removal and assimilation of prenatal and postnatal tracers, respectively. This research demonstrates that enamel can be used as a biomarker of exposure to Pb and may illustrate the toxicokinetics of incorporating Pb into fetal and neonatal steady-state system processes. The biomarker technique, when completely developed, may be applied to cross-sectional and longitudinal epidemiological research.

Ambient fine and coarse particle suppression of alveolar macrophage functions

Alveolar macrophages (AM) are part of the innate immunological defense system and are among the first cells to respond to the effects of inhaled particles. Study of macrophage responses to particles is, therefore, relevant to understanding the mechanisms by which inhaled particles can adversely affect health. Size-fractionated ambient particles were collected at traffic-dominated sites in The Netherlands using a mobile high volume slit impactor system. AM were obtained by bronchoalveolar lavage from adult as well as aged rats and were incubated with for 4 h with collected particles at concentrations of 25-1000 pg per cell. Free radical generation by AM was measured with and without stimulation of AM with phorbol myristate acetate (PMA). There were dose-dependent decreases in macrophage production of superoxide radicals as measured by the chemiluminescent method. Coarse particles were more toxic than were fine particles. Suppression of free radical production did not seem to be related to the presence of bioavailable iron or to endotoxin associated with the particles. There were no statistically significant differences related to age or strain of the rats tested. We conclude that in vitro tests using AM is a useful and rapid method for delineating differences in toxicity between environmental samples of size fractionated ambient particles.

Respiratory tract responses to repeated inhalation of an oxidant and acid gas-particle air pollutant mixture

The purpose of this study was to examine a broad range of toxicologic responses in rats exposed to a multi-component pollutant atmosphere. Cumulative and adaptive respiratory tract responses to 3 concentrations of an inhaled particle-oxidant mixture were examined in Fisher 344 N rats exposed 4 h/day, 3 days/week for 4 weeks. The mixtures contained O3, NO2, NH4HSO4, carbon particles, and HNO3 vapor. Irritant-induced, rapid-shallow breathing responses were present during the first 4-h exposure to medium and high concentrations. Successive exposures showed diminished responses in medium concentrations and exacerbated responses in high concentrations. At the end of 4 weeks, rats exposed to high concentrations exhibited lung lesions. Lavaged pulmonary macrophages showed dose-dependent depressions of Fc-receptor binding and phagocytosis. Lung tissue macrophages showed dose-dependent increases in acid phosphatase staining density and carbon particles. Respiratory tract clearance of tracer particles was not significantly affected by the exposures. Broncho-alveolar epithelial permeability was increased by the high concentration. Epithelial cell-proliferation labeling showed a dose-dependent increase at all levels of the respiratory tract. Progressively exacerbated breathing-pattern responses at high concentrations were associated with lung lesions and high cell-proliferation labeling in the nose transitional epithelium and terminal bronchioles. Attenuating or adaptive breathing-pattern responses occurred in the presence of smaller, but in many cases still significant, compromise of respiratory functions. Either attenuating or exacerbated breathing-pattern responses can occur in the presence of a significant dose-dependent compromise of other respiratory functions and lung tissue injury.

Measurements of manganese with respect to calcium in histological enamel cross sections: toward a new manganese biomarker

Airborne Mn may become an important route of exposure if the use of Mn-containing gasoline additives becomes more widespread. We report on the measurement of manganese and calcium in histological cross sections of shed deciduous tooth enamel of three human subjects. The goal of this research was to measure Mn in tooth enamel for use as a biomarker in assessing manganese exposure in cross-sectional and longitudinal studies. The histological locations can be time-specific (analogous to examining growth rings in trees). This technique, which may identify critical windows of exposure, can be important for evaluating potential vulnerability of the fetus and neonate to inhaled or ingested Mn.

Exposure of mice to tobacco smoke attenuates the toxic effect of methamphetamine on dopamine systems

Methamphetamine treatment of mice rapidly and severely depleted levels of dopamine and its metabolites, homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) in the caudate nucleus. Exposure of mice to cigarette smoke by means of nose-only breathing apparatus for 20 min twice daily over 3 days prior to drug treatment significantly attenuated the neurotoxicity of methamphetamine as judged by a lesser depletion of dopamine, DOPAC and HVA. The lesser effect of methamphetamine upon content of serotonin level was unaltered by prior inhalation of smoke. Results suggest a specific protective effect of inhaled tobacco smoke upon the effects of methamphetamine upon dopaminergic circuitry.

Toxicity of chemical components of ambient fine particulate matter (PM 2.5) inhaled by aged rats

The toxicity of two important chemical components of fine ambient particulate matter (PM 2.5)-ammonium bisulfate (ABS) and elemental carbon (C)-was studied using aged (senescent) rats. The study tested the hypotheses that fine particle exposure can damage lungs and impair host defenses in aged rats and that ozone would potentiate the toxicity of these particles. Ammonium bisulfate aerosols were generated by nebulization of dilute aqueous solutions. Elemental carbon was generated from an aqueous suspension of carbon black. Carbon and ABS mixtures were generated by nebulization of a suspension of carbon black in a dilute aqueous solution of ABS. Rats were exposed, nose-only, for 4 h a day, three consecutive days a week, for 4 weeks. The rats were exposed to one of six atmospheres: (1) purified air; (2) C, 50 microg m(-3), 0.3 microm mass median aerodynamic diameter (MMAD); (3) ABS, 70 microg m(-3), 0.3 microm MMAD; (4) O3, 0.2 ppm; (5) ABS + C, 0.46 microm MMAD; and (6) ABS + C + O3, 0.45 microm MMAD. Data were analyzed using ANOVA and Tukey multiple comparison tests; a two-tailed significance level of 0.05 was used. The nuclei of lung epithelial and interstitial cells were examined to determine the labeling of the DNA of dividing cells by 5-bromo-2-deoxyuridine and to identify the location of injury-repair-related cell replication. Increased labeling of both epithelial and interstitial lung cells occurred following all pollutant exposures. Although epithelial cells are most likely impacted by inhaled particles first, the adjacent interstitial cells were the cells that showed the greatest degree of response. Exposure to the ABS + C + O3 mixture resulted in losses of lung collagen and increases in macrophage respiratory burst and phagocytic activities that were statistically significant. Our results demonstrate that ozone can increase the toxicity of inhaled particles (or vice versa), and suggest that detailed study of mixtures could provide a more comprehensive understanding of the mechanisms by which inhaled pollutants adversely affect human health.

Evaluation of a real-time passive personal particle monitor in fixed site residential indoor and ambient measurements

Recent experimental findings in animals and humans indicate adverse respiratory effects from short-term exposures to particulate air pollutants, especially in sensitive subpopulations such as asthmatics. The relationship between air pollution and asthma has mainly been determined using particulate matter (PM) measurements from central sites. Validated tools are needed to assess exposures most relevant to health effects. Recently, a personal passive particulate sampler (personal Data-RAM, pDR, MIE Inc., Bedford, MA) has become available for studying personal exposures to PM with time resolution at 1 min. The pDR measures light scatter from PM in the 0.1-10 microM range, the significant range for health effects. In order to assess the ability of the pDR in predicting gravimetric mass, pDRs were collocated with PM2.5 and PM10 Harvard Impactors (HI) inside and outside nine homes of asthmatic children and at an outdoor central Air Pollution Control District site. Results are presented of comparisons between the HI samplers and the pDR in various modes of operation: passive, active, and active with a heated inlet. When used outdoors at fixed sites the pDR readings exhibit interference from high relative humidity (RH) unless operated with a method for drying inlet air such as a heater, or if readings at times of high RH are adjusted. The pDR correlates more highly with the HI PM2.5 than with the HI PM10 (r2 = 0.66 vs. 0.13 for outdoors, r2 = 0.42 vs. 0.20 for indoors). The pDR appears to be a useful tool for an epidemiologic study that aims to examine the relationship between health outcomes and personal exposure to peaks in PM.

Effect of serial-day exposure to nitrogen dioxide on airway and blood leukocytes and lymphocyte subsets

Nitrogen dioxide (NO2) is a free radical-producing oxidant gas. Inhalation of NO2 could cause airway inflammation, and decrease immune function. This experiment tested the hypothesis that exposure to NO2 would: 1) increase leukocytes in bronchoalveolar lavage (BAL); and 2) change the distribution of lymphocyte subsets and activation in BAL and peripheral blood (PB). Using a counter-balanced, repeated-measures design, 15 healthy volunteers were exposed to filtered air (FA) or 2.0 parts per million NO2 for 4 h x day(-1) (4 x 30 min of exercise), for three consecutive days. Bronchoscopy was performed 18 h following each exposure set, and PB was drawn pre-exposure and pre-bronchoscopy. Flow cytometry was used to enumerate lymphocyte subsets and activation makers in BAL and PB. In the bronchial fraction, there was an increase in the percentage of neutrophils following NO2 exposure compared to FA (median (interquartile range): 10.6 (4.8-17.2)% versus 5.3 (2.5-8.3)%; p=0.005). In the BAL, there was a decrease in the percentage of T-helper cells following NO2 exposure compared to FA (55.9 (40.8-62.7)% versus 61.6 (52.6-65.2)%; p=0.022). For PB, there were no between-condition differences in any leukocyte or lymphocyte subsets, or activation. In conclusion exposure to nitrogen dioxide results in bronchial inflammation and a minimal change in bronchoalveolar lavage T-helper cells, and no changes in peripheral blood cells.

The exercise-induced oxidative stress paradox: the effects of physical exercise training

BACKGROUND

Although physical exercise training is highly recommended, physical exercise causes oxidative stress, which is potentially injurious. This study evaluates this 'exercise paradox' by evaluating the effect of physical exercise on exercise-induced lipid peroxidation.

METHODS

Measurement of lipid peroxidation (ie, expired ethane and pentane and plasma malondealdehyde) taken during cardiopulmonary exercise stress testing were compared between a group of 10 cardiac patients who underwent physical exercise training in a cardiac rehabilitation setting and a group of 10 nonexercising cardiac patients.

RESULTS

Our findings indicate that physical exercise training increased physical work capacity without a concomitant increase in expired markers of lipid peroxidation (ethane and pentane) and decreased malondealdehyde levels.

CONCLUSIONS

Because physical exercise-trained people can perform more intense physical work with less oxidative stress, we conclude that physical exercise training can reduce potential chronic health effects associated with daily activities by contributing to an overall reduction in exercise-induced free radical production.

Adaptive and non-adaptive responses in rats exposed to ozone, alone and in mixtures, with acidic aerosols

Healthy young adult (300 g) Sprague-Dawley rats were exposed for 1-day or 5-day periods, nose only, to purified air (CA) or four different pollutant atmospheres. Pollutant atmospheres included (a) 0.2 ppm ozone; (b) 0.4 ppm O3; (c) a low concentration mixture of ozone and sulfuric acid-coated carbon particles (0.2 ppm, 100 microg/m(3) and 50 microg/m(3), respectively); and (d) a high-concentration O3 and sulfuric acid-coated carbon particle mixture (0.4 ppm, 500 microg/m(3) and 250 microg/m(3), respectively). Following 1-day exposures to the high O3 concentration, significant (p< or =.05) decreases were observed in respiratory tidal volumes and significant increases were observed in lung inflammatory response. Following 5-day exposures to 0.4 ppm ozone, tidal volumes and lung inflammation were not significantly different from those seen in CA controls. In contrast, following 5-day exposures to the high-concentration O3-particle mixture, lung inflammation was increased significantly relative to that seen after 1-day high concentration mixture exposure or after CA exposure. Macrophage Fc-receptor binding, an important immunological function of macrophages, was significantly depressed after 5-day exposures to either the high- or low-concentration O3-particle mixtures compared to 1-day exposures or to CA. Thus, at the concentrations tested, repeated exposures to O3 produced diminished responses in breathing pattern changes and lung parenchymal injuries compared to acute, single exposures. This diminution was not observed after exposures to mixtures of acidic particles plus ozone. We conclude that mixtures of ozone and acidic particles may alter adaptive mechanisms that have been reported by us and others after repeated exposures to ozone alone.

Urban angina in the mountains: effects of carbon monoxide and mild hypoxemia on subjects with chronic stable angina

Seventeen men with stable angina pectoris who resided at or near sea level performed cardiopulmonary exercise stress tests after they were exposed to either carbon monoxide (3.9%), carboxyhemoglobin, or clean air. Investigators conducted the tests at sea level, and they simulated 2.1-km altitudes (i.e., reduced arterial oxygen saturation by approximately 4%) in a randomized double-blind experiment in which each subject acted as his or her own control. The duration of symptom-limited exercise, heart rate, indicators of cardiac ischemia and arrhythmia, blood pressure, and respiratory gas exchange were measured. Analyses of variance showed that both independent variables-altitude and carbon monoxide-significantly (p < or = .01) reduced total duration of exercise for the group as a whole (n=17) and reduced the time to onset of angina for a subset of 13 subjects who experienced angina during all four test conditions (p < .05). Time to onset of angina was reduced either after exposure to sea-level carbon monoxide (9%) or to simulated high-altitude clean-air exposures (11%), compared with clean air at sea level. Joint exposure to carbon monoxide at a simulated high altitude reduced the time to onset of angina, relative to clean air, by 18% (p < .05). Other cardiological, hemodynamic, and respiratory physiological parameters were also affected adversely by altitude and carbon monoxide exposures. None of the parameters measured were associated significantly with either altitude or carbon monoxide, indicating that the effects of carbon-monoxide-induced and high-altitude-induced hypoxia were additive. The results of this study suggest that high-altitude conditions exacerbate the effects of carbon monoxide exposures in unacclimatized individuals who have coronary artery disease.

Exercise-induced oxidative stress in patients during thallium stress testing

BACKGROUND

Free radical injury is implicated in the pathogenesis of coronary artery disease, including atherogenesis and reperfusion/injury. Strenuous physical exercise can cause oxidative stress by several mechanisms, including reperfusion/injury. We hypothesize that exercise-induced lipid peroxidation is greater among those with than those without exercise induced myocardial ischemia.

METHODS

The effect of physical exercise stress testing on plasma malonaldehyde (MDA) levels was compared between patients with (Group A, N = 8) and without (Group B) exercise-induced myocardial ischemia by thallium imaging.

ANALYSIS

Two-way ANOVA was used to compare plasma MDA levels pre- and post-exercise, and paired t-test comparisons were conducted for percent MDA changes between Group A and Group B patients.

RESULTS

Two-way ANOVA revealed a significant (P = 0.002) directional difference in response to exercise between the groups' mean plasma MDA levels (Group A increased by 46 +/-12.7 percent, Group B decreased by 16.8+/-4.6 percent).

CONCLUSIONS

Differences in exercise-induced lipid peroxidation between patients with and without thallium documentation of myocardial ischemia have important implications in the development of clinical markers of coronary artery disease and further research related to atherogenesis.

The effect of exercise intensity on lipid peroxidation

This study characterizes exercise-induced lipid peroxidation during graded aerobic exercise in seven healthy men and women (36.4 +/- 3 yr). Levels of ethane and pentane in expired breath during cardiopulmonary exercise stress testing were measured at rest, lactic acidosis threshold (LAT), maximal exercise (VO2max), and recovery. Serum malonaldehyde (MDA) levels were measured at rest before exercise and 5 min after maximal exercise. Expired ethane and pentane flux levels were increased above resting levels at LAT, continued to rise at VO2max, then declined during recovery. Serum MDA levels were not significantly different before and after maximal exercise. Substantial exercise-induced lipid peroxidation (by expired ethane and pentane) apparently occurred in healthy individuals at LAT and continued to increase at VO2max, yet rapidly attenuated during post-exercise recovery. These findings indicate that in healthy individuals physical exercise induced lipid peroxidation transiently and that there was a removal of lipid peroxidation byproducts during recovery.

Urban ectopy in the mountains: carbon monoxide exposure at high altitude

Environmental exposure to inhaled carbon monoxide (CO) increases coronary artery disease risk. Sudden cardiac death, a frequent manifestation of coronary artery disease, is usually a result of ventricular dysrhythmia. The effect of exposure to CO at sea level (CO/SL) and simulated high (2.1 km) altitudes (CO/HA) on the incidence of cardiac ectopy in subjects with coronary artery disease was investigated. A double-blind crossover study was conducted, with random-order assignment, and each subject served as his own control. Seventeen men with documented coronary artery disease and stable angina pectoris performed cardiopulmonary exercise stress tests after random exposure to either CO or clean air (CA) at sea level (CA/SL) or at a simulated 2.1-km high altitude (CA/HA). The individual CO and HA exposure conditions were each selected to reduce the percentage of oxygen saturation of the subjects' arterial blood by 4%. Subjects' blood carboxyhemoglobin levels were increased from an average of 0.62% after clean-air exposure to 3.91% of saturation after CO exposure. The percentage of oxygen saturation in arterial blood was reduced from a baseline level of 98% to approximately 94% after CO/SL or CA/HA and to approximately 90% after CO/HA. Compared with the CA/SL (i.e., 10 premature ventricular contractions [PVCs]), the average incidence of exercise-induced ventricular ectopy was approximately doubled after all exposures (CO/SL = 18 PVCs, CA/HA = 16 PVCs, and CO/HA = 19 PVCs), and a significant trend (p < .05) of increased ectopy with decreased oxygen saturation in arterial blood was observed. Yet, among subjects who were free from ectopy (n = 11) on CA/SL, only 2 subjects developed ectopy after CO/HA. No episodes of ventricular tachycardia or fibrillation occurred. The findings indicated that exposure to increased levels of hypoxemia, resulting from hypoxic and/or CO exposures, increased the susceptibility to ventricular ectopy during exercise in individuals with stable angina pectoris; however, this risk was nominal for those without ectopy.

Surfactant dysfunction after inhalation of nitric oxide

To study whether nitric oxide (NO) affects surfactant function, 36 young rats inhaled one of the following humidified environments for 24 h: 1) air; 2) 95% O2; 3) air and 100 parts/million (ppm) NO; and 4) 95% O2 and 100 ppm NO. The treatments did not change the recovery of phospholipid from bronchoalveolar lavage (BAL). Exposure to NO of animals that breathed either air or 95% O2 increased the minimum surface tension of surfactant from BAL at low (1.5 mumol/ml), but not at high (4 mumol/ml), phosphatidylcholine concentration. After inhaled NO, the nonsedimentable protein of BAL decreased the surface activity of surfactant (1 mumol phosphatidylcholine/ml) more than the protein from the controls. NO treatment of animals that breathed either air or 95% O2 affected neither the quantity nor the molecular weight distribution of nonsedimentable protein. Hyperoxia increased the amount of the nonsedimentable protein, whereas NO increased the iron saturation of transferrin. The surfactant fraction and the nonsedimentable protein from BAL were separately exposed to 80 ppm NO in vitro. NO exposure had no effect on the surface activity of surfactant fraction. NO exposure of nonsedimentable protein from the control animals (no NO) increased the inhibition of the surface activity and changed the adsorption spectrum of the protein, suggesting conversion of hemoglobin to methemoglobin. Nonsedimentable protein from NO-exposed animals contained methemoglobin. We propose that surfactant dysfunction caused by inhaled NO is in part due to alteration of protein(s) in epithelial lining fluid that in turn inactivates surfactant.

Acute exposure to carbon monoxide does not affect plasma lipids, lipoproteins, and apolipoproteins

STUDY OBJECTIVES

To examine the effects of acute exposure to carbon monoxide and hypoxia on plasma lipids, lipoproteins, and apolipoproteins.

DESIGN

Random-order assignment to blinded, inhaled exposures of carbon monoxide and hypoxia.

SETTING

Research laboratory of ambulatory subjects.

SUBJECTS

10 elderly, male nonsmokers with chronic stable angina.

INTERVENTION

Random-order two-hour inhaled exposure to clean air at sea level, carbon monoxide at sea level, carbon monoxide at high altitude, and clean air at high altitude.

MEASUREMENTS

Fasting plasma lipids, lipoproteins, and apolipoproteins before and after exposures.

RESULTS

No differences were noted between fasting plasma lipid, lipoprotein, or apolipoprotein levels before and after exposures.

CONCLUSION

Acute exposure to carbon monoxide and high altitude does not affect fasting plasma lipid, lipoprotein, or apolipoprotein levels.

Chronic inhalation exposure to ozone and nitric acid elevates stress-inducible heat shock protein 70 in the rat lung

The ability of urban oxidant and acid air pollutants to induce heat shock proteins (HSPs) in the mammalian lung is not known. Such proteins are known to be correlated with environmental stress and pathophysiological conditions. In this study, stress-inducible HSP 70 was assessed by slot-blotting in rat lungs (N=10 per group) following inhalation exposures for 4 h per day, 3 days per week for 40 weeks to the following pollutants: (a) purified air;(b) 0.15 ppm ozone (O3);(c)50 micrograms/m3 nitric acid (HNO3); or(d) a combination of both 0.15 ppm O3 and 50 micrograms/m3 HNO3. At 24 h following the last exposure, samples from the right apical lobe of the lung were obtained for either slot-blotting or gel electrophoretic separation, subsequent protein immunoblotting, and chemiluminescence detection of HSP 70 levels. Experiments demonstrate that stress-inducible HSP 70 was present constitutively in the control lungs and was separable from the constitutive form of HSP 70. Slot-blotting analysis demonstrate that the O3 and HNO3 exposures alone produced significant elevations of HSP70. Specifically, either O3 or HNO3 alone significantly elevated lung stress-inducible HSP 70 levels by 277% and 221% respectively, above control levels. The group exposed to combined O3 and HNO3 showed a 177% elevation in lung stress-inducible HSP 70 that was significantly greater that the group inhaling purified air, but this effect was less than the effects of either pollutant component alone. Moreover, all exposure groups were significantly different from one another. These results indicate that stress-inducible HSP 70 in the rat lung is highly elevated after chronic inhalation exposures to both O3 and HNO3 when administered either alone or in combination within the range of urban ambient concentrations.

Inhalation of resuspended road dust, but not ammonium nitrate, decreases the expression of the pulmonary macrophage Fc receptor

Pulmonary macrophages (PM) play a key role in the immune defenses of the lung. When stimulated, PM express Fc receptors (FcR) that regulate the immune response. PM were assayed for FcR expression following subchronic inhalation exposure of adult Fischer 344 rats to either 90 micrograms/m3 nitrate (NH4NO3), 300 micrograms/m3 road dust, or clean air, for 4 h/day, 4 days/week, for 8 weeks. PM were lavaged from the lungs and attached to glass coverslips for 18 h. PM FcR were labelled with rat IgG conjugated with cyanine-3. For each exposure, FcR were determined with a Meridian ACAS 570 confocal cytometer by imaging the fluorescence of 50 cells. We found that the IgG binding to FcR (in arbitrary fluorescence units, FU, per cell) for PM from road dust exposed rats was less (835 +/- 39.3 FU/cell) than that for PM from both ammonium nitrate or clean air-exposed rats (1115 +/- 58.0 FU/cell and 1123 +/- 46.6 FU/cell, respectively). While acid incubation conditions in vitro (pH 5.5 for 30 min to simulate the acid environment of ammonium nitrate inhalation) resulted in a 16% decrease in IgG binding (P < 0.05), IgG binding to PM from acid aerosol exposed rats was no different than the IgG bound to PM from clean air-exposed rats. PM exposed to road dust in vivo expressed 25% fewer FcR (P < 0.05). Three-dimensional images of PM failed to show any major alterations in FcR distribution. These preliminary results indicate cellular recognition of antibody-immune complexes may be impaired by subchronic exposure to road dust, which could decrease the immune response of road dust exposed animals.

Valuing the health benefits of clean air

An assessment of health effects due to ozone and particulate matter (PM10) suggests that each of the 12 million residents of the South Coast Air Basin of California experiences ozone-related symptoms on an average of up to 17 days each year and faces an increased risk of death in any year of 1/10,000 as a result of elevated PM10 exposure. The estimated annual economic value of avoiding these effects is nearly $10 billion. Attaining air pollution standards may save 1600 lives a year in the region.

The effects of exercise on dose and dose distribution of inhaled automotive pollutants

The purpose of this study was to determine how changes in ventilation rate and in the entry route of air pollutants into the respiratory tract (nose versus mouth breathing) affected the respiratory tract uptake and penetration of inhaled gaseous and particulate pollutants associated with automobile emissions. Experiments were performed with female beagle dogs exposed while standing at rest or while exercising on a treadmill at 5 km/hour and a 7.5 percent grade. Dogs were exposed to nitrogen dioxide at concentrations of 1 and 5 parts per million (ppm), to formaldehyde at 2 and 10 ppm, and to an aerosol of ammonium nitrate particles (0.3 micron mass median aerodynamic diameter) at 1 mg/m3. Total respiratory system uptake and effects on breath time, expired tidal volume, fractional expiration time, minute ventilation, respiratory gas exchange, ventilation equivalents for oxygen and carbon dioxide, and dynamic pulmonary resistance and compliance were measured in exercising and resting dogs exposed for two hours to 5 ppm nitrogen dioxide and 10 ppm formaldehyde in combination with 1 mg/m3 of ammonium nitrate particles. Regional penetration of pollutants through oral and nasal airways and pollutant uptake in the lung were measured in a separate group of six tracheostomized dogs standing at rest while being exposed to nitrogen dioxide, formaldehyde, and ammonium nitrate particles. Hypercapnic stimulation was used to modify ventilation rates in the tracheostomized dogs while pollutant penetration and uptake were measured. Dogs exposed to 5 ppm of nitrogen dioxide at rest tended to breathe more rapidly (p less than 0.05) and more shallowly (a nonsignificant trend) than dogs exposed to purified air. The changes observed were similar in direction, but of smaller magnitude, to changes observed when the same dogs were exposed during exercise to ozone at 0.6 ppm in a separate study. Rapid-shallow breathing was not observed when the dogs were exposed during exercise to 5 ppm nitrogen dioxide. Dogs exposed to a mixture of 10 ppm formaldehyde and 1 mg/m3 ammonium nitrate particles during exercise showed a shift to larger tidal volume breathing, but the response was much less pronounced than the slow-deep breathing pattern response observed in a separate study of dogs exposed to 10 ppm formaldehyde alone. The total respiratory system uptake of formaldehyde from the formaldehyde and ammonium nitrate mixture was larger than that measured for 10 ppm of formaldehyde alone in another exercise and exposure study.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of short-term exposure to carbon monoxide in subjects with coronary artery disease

Twenty-four male subjects with stable angina pectoris performed graded exercise tests after being exposed to either carbon monoxide (CO) or clean air in a randomized crossover double-blind experiment in which each subject acted as his own control. Subject's blood carboxyhemoglobin levels were increased from a baseline level of approximately 1.5% to 3% of saturation, post-CO exposure. Cardiographic and respiratory gas exchange data were obtained during the tests in which the subjects exercised to the point of onset of anginal pain. The goal of the study was to determine if low-level CO exposure compromised the ability of these individuals to perform work. Data were evaluated statistically using a two-factor analysis of variance with repeated measures; the factors were exposure ATMOSPHERE (clean air vs. CO) and ORDER of exposure (clean air first, CO second vs. CO first, clean air second). One-tailed tests were used, and differences were considered significant at the p less than .05 level. The time to onset of angina was reduced 6% (p = .046) after CO exposure relative to clean air. Oxygen uptake (VO2) at angina was reduced by approximately 3% (p = .04). A subgroup of individuals who exhibited depression in the ST segment of their electrocardiograph tracings showed a 12% reduction in time to onset of angina and a 20% reduction in the time to onset of 0.1 mV ST segment depression; both of these findings were also statistically significant.

Health effects of acid aerosols formed by atmospheric mixtures

Under ambient conditions, sulfur and nitrogen oxides can react with photochemical products and airborne particles to form acidic vapors and aerosols. Inhalation toxicological studies were conducted, exposing laboratory animals, at rest and during exercise, to multicomponent atmospheric mixtures under conditions favorable to the formation of acidic reaction products. Effects of acid and ozone mixtures on early and late clearance of insoluble radioactive particles in the lungs of rats appeared to be dominated by the oxidant component (i.e., the mixture did cause effects that were significantly different from those of ozone alone). Histopathological evaluations showed that sulfuric acid particles alone did not cause inflammatory responses in centriacinar units of rat lung parenchyma (expressed in terms of percent lesion area) but did cause significant damage (cell killing followed by a wave of cell replication) in nasal respiratory epithelium, as measured by uptake of tritiated thymidine in the DNA of replicating cells. Mixtures of ozone and nitrogen dioxide, which form nitric acid, caused significant inflammatory responses in lung parenchyma (in excess of effects seen in rats exposed to ozone alone), but did not damage nasal epithelium. Mixtures containing acidic sulfate particles, ozone, and nitrogen dioxide damaged both lung parenchyma and nasal epithelia. In rats exposed at rest, the response of the lung appeared to be dominated by the oxidant gas-phase components, while responses in the nose were dominated by the acidic particles. In rats exposed at exercise, however, mixtures of ozone and sulfuric acid particles significantly (2.5-fold) elevated the degree of lung lesion formation over that seen in rats exposed to ozone alone under an identical exercise protocol.

Effects of exercise exposure on toxic interactions between inhaled oxidant and aldehyde air pollutants

Respiratory tract injury resulting from inhalation of mixtures of ozone (O3) and nitrogen dioxide (NO2) and of O3 and formaldehyde (HCHO) was studied in Sprague-Dawley rats under exposure conditions of rest and exercise. Focal inflammatory injury induced in lung parenchyma by O3 exposure was measured morphometrically and HCHO injury to the nasal respiratory epithelium was measured by cell turnover using tritium-labeled thymidine. Mixtures of O3 (0.35 or 0.6 ppm) with NO2 (respectively 0.6 or 2.5 ppm) doubled the level of lung injury produced by O3 alone in resting exposures to the higher concentrations and in exercising exposures to the lower concentrations. Formaldehyde (10 ppm) mixed with O3 (0.6 ppm) resulted in reduced lung injury compared to O3 alone in resting exposures, but exercise exposure to the mixture did not show an antagonistic interaction. Nasal epithelial injury from HCHO exposure was enhanced when O3 was present in a mixture. Mixtures of O3 and NO2 at high and low concentrations formed respectively 0.73 and 0.02 ppm nitric acid (HNO3) vapor. Chemical interactions among the oxidants, HNO3, and other reaction products (N2O5 and nitrate radical) and lung tissue may be the basis for the O3-NO2 synergism. Increased dose and dose rate associated with exercise exposure may explain the presence of synergistic interaction at lower concentrations than observed in resting exposure. No oxidation products were detected in O3-HCHO mixtures, and the antagonistic interaction observed in lung tissue during resting exposure may result from irritant breathing pattern interactions.

Tracheal and bronchoalveolar permeability changes in rats inhaling oxidant atmospheres during rest or exercise

Permeability of tracheal and bronchoalveolar airways of rats was measured and used to examine the effects of inhaled oxidant-containing atmospheres. The atmospheres studied were (a) ozone (O3) at 0.6 ppm (1.2 mg/m3) or 0.8 ppm (1.6 mg/m3); (b) nitrogen dioxide (NO2) at 6 ppm (11.3 mg/m3) or 12 ppm (22.6 mg/m3); (c) O3 + NO2 at 0.6 ppm (1.2 mg/m3) and 2.5 ppm (4.7 mg/m3), respectively; and (d) a 7-component particle and gas mixture (complex atmosphere) representing urban air pollution in a photochemical environment. The rats were exposed for 2 h. The effects of exercise during exposure were evaluated by exposing additional groups in an enclosed treadmill. Exposure of resting rats to 0.8 ppm O3 increased tracheal permeability to DTPA and bronchoalveolar permeability to diethylenetriamine pentaacetate (DTPA) and bovine serum albumin (BSA) at 1 h after the exposure. Bronchoalveolar, but not tracheal, permeability remained elevated at 24 h after the exposure. Exercise during exposure to O3 increased permeability to both tracers in the tracheal and the bronchoalveolar zones, and prolonged the duration of increased permeability in the tracheal zone from 1 h to 24 h, and in the bronchoalveolar zone from 24 h to 48 h. Permeability in the tracheal and bronchoalveolar zones of rats exposed at rest to 6 or 12 ppm NO2 did not differ from controls. However, rats exposed during exercise to 12 ppm NO2 for 2 h developed a significant increase in tracheal and bronchoalveolar permeability to DTPA and BSA at 1 h, but not at 24 or 48 h, after exposure. Exposure at rest to 0.6 ppm O3 plus 2.5 ppm NO2 significantly increased bronchoalveolar permeability at 1 and 24 h after exposure, although exposure at rest to 0.6 ppm O3 alone increased bronchoalveolar permeability only at 1 h after exposure. Exposure to O3 + NO2 during exercise led to significantly greater permeability to DTPA than did exercising exposure to O3 alone. Resting rats exposed to a complex gas/aerosol atmosphere composed of the above O3 and NO2 concentrations, plus 5 ppm (13.1 mg/m3) sulfur dioxide (SO2) and an aerosol of insoluble colloidal Fe2O3 with an aerosol of manganese, ferric, and ammonium salts, demonstrated increased permeability at 1 and 24 h after exposure. Nitric acid vapor was formed in both the O3 + NO2 atmosphere and the complex gas/aerosol atmosphere.(ABSTRACT TRUNCATED AT 400 WORDS)

Relative permeability of nasal, tracheal, and bronchoalveolar mucosa to macromolecules in rats exposed to ozone

Nasal, tracheal and bronchoalveolar injuries resulting from acute ozone exposure of rats were investigated by permeability changes. 99mTc-labeled diethylenetriaminepentaacetate (DPTA) and 125I-labeled bovine serum albumin (BSA) were selectively instilled into localized airway regions of anesthetized rats exposed to 0.8 ppm 03 or clean air for 2 h. Transmucosal transfer of the radiolabeled tracers was detected by counting the radioactivity in blood samples collected at short postinstillation time intervals. Permeability measurements were made on d 0, 1, and 2 after O3 exposure to analyze the extent and persistence of tissue injury in the nasal, tracheal, and bronchoalveolar regions. Normal mucosal permeability was low in nose, intermediate in bronchoalveolar zone, and high in trachea. The O3-related injury, reflected by elevated permeability, was substantial in the trachea and bronchoalveolar zone but was minimal in the nose immediately after the exposure. Abnormal permeability persisted for less than 24 h in the trachea but for more than 24 h in the bronchoalveolar zone. The results are consistent with the properties of O3 of causing greater injury in the smaller airways and the alveolar zone than in the trachea.

Controlled exposure to a mixture of SO2, NO2, and particulate air pollutants: effects on human pulmonary function and respiratory symptoms

Exposure of 20 volunteers to sodium chloride (NaCl) aerosol or to a mixture containing NaCl plus irritant particles (zinc ammonium sulfate) and irritant gases (nitrogen dioxide and sulfur dioxide) produced no significant decrements in pulmonary function. There was a slight tendency for respiratory symptoms to be greater during the exposure to the mixture than during exposure to the NaCl aerosol alone; the differences were not statistically significant. The pollutant concentrations studied approximated worst-case ambient levels observed in the Los Angeles basin.

Respiratory responses of humans exposed to an aerosol-gas pollutant mixture: multivariate contrast of a complex atmosphere to clean air and sodium chloride aerosol controls

Data from a group of 20 subjects with normal baseline pulmonary function, who were exposed for 2 h to a test atmosphere containing a complex mixture of pollutants, have been contrasted with data from two other groups exposed to presumably non-toxic control atmospheres. Group 1 was exposed to clean air, group 2 was exposed to clean air containing sodium chloride aerosol at 270 micrograms m-3, and group 3 was exposed to the complex atmosphere containing sodium chloride (332 micrograms m-3) and zinc ammonium sulfate (23 micrograms m-3) aerosols plus nitrogen dioxide (0.5 ppm) and sulfur dioxide (0.5 ppm). These atmospheres (ranked according to the presumed relative toxicities of the components; clean air = 0, sodium chloride = 1, complex mixture = 2) were contrasted using multiple regression and partial correlation analyses. The effects of exposure to the complex gas-aerosol mixture on forced expiratory performance were not significantly different from those observed in subjects exposed to clean air or to sodium chloride aerosol.

Effects of 0.2 ppm nitrogen dioxide on pulmonary function and response to bronchoprovocation in asthmatics

To study the respiratory effects of nitrogen dioxide (NO2) at ambient concentrations, we exposed 31 asthmatic volunteers to purified air (control) and to 0.2 ppm NO2 for 2-h periods with light intermittent exercise. Bronchial reactivity (loss of forced expiratory performance in response to graded doses of methacholine chloride aerosol) was determined postexposure, using a newly developed apparatus that allowed accurate quantitation of methacholine dose. Forced expiratory performance, total respiratory resistance, and symptoms were also recorded immediately pre- and postexposure (prior to methacholine challenges). No significant direct effect of NO2 exposure on forced expiratory function or total respiratory resistance was observed. Symptoms showed a small significant (p less than 0.05) excess in purified air relative to NO2 exposures. Individual responses to methacholine varied greatly. About two-thirds of the subjects showed greater response after NO2 than after purified air, but the mean excess response was small. Mean changes attained significance in some but not all applicable statistical tests. Thus we cannot conclude unequivocally that NO2 exposure increased bronchial reactivity in this group, although there was some tendency in that direction.

Human exposure to ferric sulfate aerosol: effects on pulmonary function and respiratory symptoms

Twenty normal and 18 asthmatic human volunteers were exposed to ferric sulfate aerosol at a nominal concentration of 75 microgram/m3 (equivalent to 20 microgram iron/m3). The concentration and particle size distribution (2 micron mass median aerodynamic diameter; geometric standard deviation of 3) were selected to simulate worst case ambient conditions. Ferric sulfate was chosen for study because it is toxic, it is a respiratory system irritant, and increased use of coal and high sulfur fuel oils will lead to increased concentrations of iron and sulfate in ambient air. A double-blind protocol was followed in which each subject was exposed on two days, separated by about a three week period. The subjects were exposed to clean air (sham) on one day and to ferric sulfate aerosol on the other (exposure); the order of exposure was selected randomly. Neither the subjects nor the staff performing the clinical testing were informed as to the nature of the atmosphere on any given day. Pulmonary function tests were performed immediately before (pre) and after (post) each 2 hr sham or exposure period; this protocol included intermittent exercise. Pre- and post-exposure symptom score interviews were also administered. On the average, the two groups of subjects did not exhibit significant pre- to post-changes in total respiratory system resistance, forced expiratory flow/volume performance, and single breath nitrogen washout parameters. None of the subjects reported more than slight changes in symptoms during exposure. Five individuals showed small but significant decremental trends in pulmonary function; however, nine subjects tended to improve after exposure.

Exposures of human volunteers to a controlled atmospheric mixture of ozone, sulfur dioxide and sulfuric acid

Nineteen human volunteers with normal pulmonary function and no history of asthma were exposed on two separate days to clean air and to an atmospheric mixture containing ozone (O3), 0.37 ppm, sulfur dioxide (SO2), 0.37 ppm, and sulfuric acid aerosol (B2SO4), 100 micrograms/m3. Subjects were exposed under carefully controlled conditions for two hours. During this period, the subjects alternately exercised for 15 minutes, at a level calculated to double minute ventilation, and rested for 15 minutes. The experimental goal was to determine whether the presence of the copollutants, H2SO4 and SO2, would significantly enhance the irritant potential of ozone, or cause decrements in pulmonary function on the order of 10 - 20 percent. Statistical analysis of the group averaged data suggested that the mixture may have been slightly more irritating to the subjects than was O3 alone. A large percentage of the subjects exhibited small decrements in pulmonary function. The group averaged FEV1.0 (forced expiratory volume in one second) on the exposure day was depressed 3.7 percent from the control value. One might expect O3 alone to depress FEV1.0 by about 2.8 percent under similar exposure conditions.

Controlled exposures of human volunteers to sulfate aerosols. Health effects and aerosol characterization

Our laboratory has undertaken the study of possible acute adverse health effects of sulfate aerosols through controlled exposures of volunteer human subjects. Both healthy and asthmatic adult men were exposed for 2-hour periods (with intermittent exercise) to ammonium sulfate, ammonium bisulfate, and sulfuric acid of particle size distributions and concentrations intended to simulate "worst case" exposures during Los Angeles smog episodes. Lung function tests were performed by the subjects on entering and before exiting from a carefully controlled environmental chamber. Subject symptoms were evluated in a standardized manner. Aerosol concentrations and size distributions were determined by an on-line computer/aerometric monitoring system; gravimetric and chemical analyses were performed on impactor and total filter samples after test exposures. We found little or no evidence of adverse health effects from 2-hour multiple-day exposures to any of the compounds at "worst case" ambient concentrations.