Oxidative damage of sulfur dioxide inhalation on brains and livers of mice

Neo-construction of a SO2-tunable near-infrared ratiometric fluorescent probe for high-fidelity diagnosis and evaluation hazards of Cd2+-induced liver injury

Cadmium-contaminated water and food are seriously hazardous to the human health, especially liver injury. To understand the entanglement relationship between cadmium ion (Cd2+)-induced liver injury and the biomarker sulfur dioxide (SO2), a reliable bioanalytical tool is urgently needed, detecting SO2 to diagnose and evaluate the extent of liver injury in vivo. Herein, based on the Förster resonance energy transfer (FRET) mechanism, a novel SO2-tunable NIR ratiometric fluorescent probe (SMP) was developed, it was used to diagnose and treat liver injury induced by Cd2+ in biosystems. Specifically, it was constructed by conjugating a NIR dicyanoisophorone with a NIR benzopyranate as the donor and acceptor, respectively, and the ratiometric response of SO2- regulated by the Michael addition reaction. In addition, SMP exhibits rapid reaction time (<15 s), two well-resolved emission peaks (68 nm) with less cross-talk between channels for high imaging resolution, superior selectivity, and low limit of detection (LOD=80.3 nM) for SO2 detection. Impressively, SMP has been successfully used for intracellular ratiometric imaging of Cd2+-induced SO2 and diagnostic and therapeutic evaluation in liver injury mice models with satisfactory results. Therefore, SMP may provide a powerful molecular tool for revealing the occurrence and development relationship between SO2 and Cd2+-induced liver injury. ENVIRONMENTAL IMPLICATION: Cadmium ions are one of the well-known toxic environmental pollutants, which are enriched in the human body through inhalation of cadmium-contaminated air or from the food chain, leading to damage in various organs, especially liver injury. Therefore, we developed a novel fluorescent probe that can specifically detect SO2 in Cd2+-induced liver injury, which is critically important for the diagnosis and evaluation of Cd2+-induced liver injury diseases. The specific detection of SO2 of this probe has been successfully demonstrated in live HepG2 cells and Cd2+-induced liver injury mice.

The association between intermediate-term sulfur dioxide exposure and outpatient visits for Parkinson's disease: a time-series study in southwestern China

Parkinson's disease (PD) is the second most common human neurodegenerative disorder, and the pathogenesis of it remains poorly understood. Limited studies have shown that both long- and short-term exposure to air pollutants may be associated with increased risk of PD while lacking evidence on the effects of intermediate-term exposure. In this study, over-dispersed Poisson generalized additive models (GAMs) were applied to explore the association between intermediate-term sulfur dioxide (SO2) exposure and outpatient visits for PD in Chongqing, China, and further stratified analyses were performed by age and gender. A total of 39,984 PD cases from January 1, 2014, to December 31, 2019 (2191 days) were included. The association of intermediate-term SO2 exposure with outpatient visits for PD was statistically significant: per 1 μg/m3 increase of SO2 corresponded to 2.34% (95% CI: 0.88%, 3.80%) elevation in monthly PD outpatient visits at lag 0 (the concurrent month). Stratified analyses showed that the associations between SO2 and PD outpatient visits were stronger in younger (≤ 60 years) and female patients. In conclusion, intermediate-term SO2 exposure can be associated with an increased risk of PD outpatient visits. Our results highlight the importance of recognizing the role of intermediate-term SO2 exposure in the development of PD. In addition to focusing on the effects of long-term or short-term air pollutants, it is necessary to pay more attention to the health effects of intermediate-term exposure time windows of air pollutants, which will facilitate policy formulation and public health interventions for health risks.

Effects of the apricot diets containing sulfur dioxide at different concentrations on rat testicles

Due to its antioxidant and antimicrobial properties, sulfur dioxide (SO₂) is widely used in foods and beverages to prevent the growth of microorganisms and to preserve the color and flavor of fruits. However, the amount of SO₂ used in fruit preservation should be limited due to its possible adverse effects on human health. The present study was designed to investigate the effects of different SO₂ concentrations in apricot diets on rat testes. Animals were randomly divided into six groups. The control group was fed a standard diet, and the other groups were fed apricot diet pellets prepared with (w/w) 10% dried apricots containing SO₂ at different concentrations (1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, and 3500 ppm/kg) for 24 weeks. After sacrification, testicles were evaluated biochemically, histopathologically, and immunohistopathologically. Our results showed that an apricot diet containing 1500 ppm and 2000 ppm SO₂ did not cause significant changes in testis. However, it was determined that tissue testosterone levels decreased as the amount of SO₂ (2500 ppm and above) increased. Apricot diet containing 3500 ppm SO₂ caused a significant increase in spermatogenic cell apoptosis, oxidative damage, and histopathological changes. In addition, a decrease in the expression of connexin-43, vimentin, and 3β-hydroxysteroid dehydrogenase (3β-HSD) was observed in the same group. In summary, the results show that sulfurization of apricot at high concentrations such as 3500 ppm may lead to male fertility problems in the long term through mechanisms such as oxidative stress, spermatogenic cell apoptosis, and inhibition of steroidogenesis.

The Effect of Maternal Exposure to Air Pollutants and Heavy Metals during Pregnancy on the Risk of Neurological Disorders Using the National Health Insurance Claims Data of South Korea

The objective of this study was to evaluate the effects of high levels of maternal exposure to ambient air pollution and heavy metals on risks of autism spectrum disorder (ASD) and epilepsy using the National Health Insurance claims data of South Korea. The data of mothers and their newborns from 2016 to 2018 provided by the National Health Insurance Service were used (n = 843,134). Data on exposure to ambient air pollutants (PM2.5, CO, SO₂, NO₂, and O₃) and heavy metals (Pb, Cd, Cr, Cu, Mn, Fe, Ni, and As) during pregnancy were matched based on the mother's National Health Insurance registration area. SO₂ (OR: 2.723, 95% CI: 1.971-3.761) and Pb (OR: 1.063, 95% CI: 1.019-1.11) were more closely associated with the incidence of ASD when infants were exposed to them in the third trimester of pregnancy. Pb (OR: 1.109, 95% CI: 1.043-1.179) in the first trimester of pregnancy and Cd (OR: 2.193, 95% CI: 1.074-4.477) in the third trimester of pregnancy were associated with the incidence of epilepsy. Thus, exposure to SO₂, NO₂, and Pb during pregnancy could affect the development of a neurologic disorder based on the timing of exposure, suggesting a relationship with fetal development. However, further research is needed.

Long-term exposure to ambient air pollution and serum liver enzymes in older adults: a population-based longitudinal study

PURPOSE

To investigate the association of long-term exposure to ambient air pollution with serum liver enzymes in older adults.

METHODS

In this longitudinal study, we investigated 318,911 adults aged ≥65 years and assessed their long-term residential exposure to particulate matter with an aerodynamic diameter ≤2.5 µm (PM_2.5), particulate matter with an aerodynamic diameter ≤10 µm (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃). Linear mixed models and generalized linear mixed models were implemented for exposure-response analyses.

RESULTS

Each interquartile range (IQR) increase of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ exposures was significantly associated with a 4.6%, 4.6%, 5.6%, 4.6%, 6.2%, and 3.6% increase in alanine aminotransferase (ALT), and a 4.6%, 5.2%, 3.6%, 3.3%, 6.1%, and 4.0% increase in aspartate aminotransferase (AST), respectively. Each IQR increase of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ exposures was significantly associated with a 23%, 24%, 28%, 17%, 31%, and 19% increase in odds of elevated ALT (>40 U/L), and a 32%, 39%, 40%, 32%, 57%, and 25% increase in odds of elevated AST (>40 U/L), respectively.

CONCLUSIONS

Long-term exposure to ambient air pollution was significantly associated with increased serum liver enzyme levels in older adults, suggesting that air pollution exposures may induce hepatocellular injury.

Short-term effects and economic burden assessment of ambient air pollution on hospitalizations for schizophrenia

The evidence on the health and economic impacts of air pollution with schizophrenia is scarce, especially in developing countries. In this study, we aimed to systemically examine the short-term effects of PM_2.5 (particulate matter ≤ 2.5 μm in diameter), PM₁₀ (≤ 10 μm in diameter), NO₂ (nitrogen dioxide), SO₂ (sulfur dioxide), CO (carbon monoxide), and O₃ (ozone) on hospital admissions for schizophrenia in a Chinese coastal city (Qingdao) and to further assess the corresponding attributable risk and economic burden. A generalized additive model (GAM) was applied to model the impact of air pollution on schizophrenia, and the corresponding economic burden including the direct costs (medical expenses) and indirect costs (productivity loss). Stratified analyses were also performed by age, gender, and season (warm or cold). Our results showed that for a 10 μg/m³ increase in the concentrations of PM_2.5, PM₁₀, SO₂, and CO at lag5, the corresponding relative risks (RRs) were 1.0160 (95% CI: 1.0038-1.0282), 1.0097 (1.0018-1.0177), 1.0738 (1.0222-1.01280), and 1.0013 (1.0001-1.0026), respectively. However, no significant effect of NO₂ or O₃ on schizophrenia admissions was found. The stratified analysis indicated that females and younger individuals (< 45 years old) appeared to be more vulnerable, but no significant difference was found between seasons. Furthermore, 12.41% of schizophrenia hospitalizations were attributable to exposure to air pollution exceeding the World Health Organization (WHO) air quality standard, with a total economic burden of 89.67 million RMB during the study period. At the individual level, excessive air pollution exposure resulted in an economic burden of 8232.08 RMB per hospitalization. Our study found that short-term exposure to air pollutants increased the risk of hospital admissions for schizophrenia and resulted in a substantial economic burden. Considerable health benefits can be achieved by further reducing air pollution.

Exposure to air pollutants during pregnancy and after birth increases the risk of neonatal hyperbilirubinemia

OBJECTIVES

Exposure to air pollution is associated with increased risks of several adverse conditions in newborns, such as preterm birth. Whether air pollution is associated with neonatal hyperbilirubinemia remains unclear. We aimed to develop and validate an air-quality-based model to better predict neonatal hyperbilirubinemia.

METHODS

A multicenter, population-based cohort of neonates with a gestational age (GA) ≥35 weeks and birth weight ≥2000 g was enrolled in the study. The study was conducted in Shanghai, China, from July 2017 to December 2018. The daily average concentrations of particulate matter (PM) with aerodynamic diameters≤2.5 μm (PM2.5) and ≤10 μm (PM10), sulfur dioxide (SO₂), nitrogen dioxide (NO2) and carbon monoxide (CO) were measured. Neonatal hyperbilirubinemia was diagnosed according to the American Academy of Pediatrics (AAP) guidelines by trained neonatologists. We used logistic least absolute shrinkage and selection operator (LASSO) regression to screen air pollutant indicators related to neonatal hyperbilirubinemia and build an air-quality signature for each patient. An air-quality-based nomogram was then established to predict the risk of neonatal hyperbilirubinemia.

RESULTS

A total of 11196 neonates were evaluated. Prenatal PM10, CO and NO₂ exposure and postpartum SO₂ exposure were significantly associated with neonatal hyperbilirubinemia. The air-quality score was calculated according to the hyperbilirubinemia-related pollutants. The air-quality score of the hyperbilirubinemia group was significantly higher than that of the nonhyperbilirubinemia group (P < .01, odds ratio = 2.97). An air-quality-based logistic regression model was built and showed good discrimination (C-statistic of 0.675 [95% CI (confidence interval), 0.658 to 0.692]) and good calibration. Decision curve analysis showed that the air-quality-based model was better than the traditional clinical model in predicting neonatal hyperbilirubinemia.

CONCLUSIONS

The findings of this study suggest that ambient air pollution exposure is associated with an increased risk of neonatal hyperbilirubinemia. Our results encourage further exploration of this possibility in future studies.

A dual responsive fluorescent probe for selective detection of cysteine and bisulfite and its application in bioimaging

A coumarin-based dual responsive fluorescent probe with a simple structure was developed for the detection of Cys and HSO3 -. Under simulated physiological conditions, Cou-F displayed an on-off fluorescence response to Cys at 521 nm and an off-on fluorescence response to HSO3 - at 500 nm. Furthermore, Cou-F had the advantages of high sensitivity, strong specificity and rapid response. The detection limits of Cou-F toward Cys and HSO3 - were 0.54 μM and 0.65 μM, respectively. Cou-F enabled high selective responses to Cys and HSO3 - over other biologically related species. The response times of Cou-F toward Cys and HSO3 - were 80 s and 100 s. The fluorescence imaging of Cys and HSO3 - was achieved in living RAW246.7 cells.

Air Pollution-Related Brain Metal Dyshomeostasis as a Potential Risk Factor for Neurodevelopmental Disorders and Neurodegenerative Diseases

Increasing evidence links air pollution (AP) exposure to effects on the central nervous system structure and function. Particulate matter AP, especially the ultrafine (nanoparticle) components, can carry numerous metal and trace element contaminants that can reach the brain in utero and after birth. Excess brain exposure to either essential or non-essential elements can result in brain dyshomeostasis, which has been implicated in both neurodevelopmental disorders (NDDs; autism spectrum disorder, schizophrenia, and attention deficit hyperactivity disorder) and neurodegenerative diseases (NDGDs; Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis). This review summarizes the current understanding of the extent to which the inhalational or intranasal instillation of metals reproduces in vivo the shared features of NDDs and NDGDs, including enlarged lateral ventricles, alterations in myelination, glutamatergic dysfunction, neuronal cell death, inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, altered social behaviors, cognitive dysfunction, and impulsivity. Although evidence is limited to date, neuronal cell death, oxidative stress, and mitochondrial dysfunction are reproduced by numerous metals. Understanding the specific contribution of metals/trace elements to this neurotoxicity can guide the development of more realistic animal exposure models of human AP exposure and consequently lead to a more meaningful approach to mechanistic studies, potential intervention strategies, and regulatory requirements.

Association between long-term exposure to Sulfur dioxide pollution and hypertension incidence in northern China: a 12-year cohort study

Several studies have researched the short-term effect of sulfur dioxide (SO₂) exposure on hypertension. However, no evidence has provided the relationship between long-term high pollution exposure of SO₂ and morbidity of hypertension in cohort studies in China. This retrospective cohort study aimed to evaluate this association. We used Cox proportional hazards regression models to examine the hazard ratios (HR) for hypertension risks from 1998 to 2009 associated with accumulative exposure of air SO₂ among adults in northern China. Annual average concentrations of sulfur dioxide (SO₂) were obtained from 15 local environmental monitoring centers. Hypertension was identified according to self-reported diagnostic time and treatment for hypertension with anti-hypertensive medication. Among 37,386 participants, 2619 new cases of hypertension were identified during 426,334 person-years. In the fully adjusted model, HR and 95% confidence interval (CI) of hypertension incidence for each 10 μg/m³ increase in SO₂ were 1.176 (1.163 and 1.189). Results from stratified analyses suggested that effects of SO₂ on hypertension morbidity were more pronounced in participants < 60 years old, tea drinkers, and those with high education, high poultry consumption, and active (occasional and frequent) exercise. We found that long-term exposure to high levels of SO₂ increased the risk of incidence of hypertension in China.

A glutathione-responsive sulfur dioxide polymer prodrug as a nanocarrier for combating drug-resistance in cancer chemotherapy

Multidrug resistance (MDR) in cancer remains a significant challenge for curing cancer by chemotherapy. In this work, a kind of glutathione (GSH)-responsive polymer prodrug of SO₂ was designed and synthesized, which presented synergistic effect with doxorubicin (DOX) for combating MCF-7 ADR human breast cancer cell. Firstly, a small molecular prodrug of SO₂, N-(3-azidopropyl)-2,4-dinitrobenzenesulfonamide (AP-DNs), was chemically conjugated onto the side chain of methoxy poly (ethylene glycol)-block-poly (γ-propargyl-l-glutamate) (mPEG-PPLG) block copolymer to generate an amphiphilic polymer prodrug of SO₂, mPEG-PLG (DNs). The obtained mPEG-PLG (DNs) prodrug could self-assemble into micelles in aqueous media and release SO₂ rapidly in response to thiol compounds. Then, DOX was loaded into mPEG-PLG (DNs) nanoparticles with ultrahigh drug-loading efficiency (97.3%). In vitro drug release tests indicated that the DOX-loaded nanoparticles could simultaneously release SO₂ and DOX by GSH triggering. Moreover, the effective cellular uptake of the DOX-loaded nanoparticles and subsequent intracellular release of SO₂ and DOX were verified by confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) analyses. The released SO₂ could promote the reactive oxygen species (ROS) level in tumor cells, which thereby resulted in oxidative damages of cancer cells, together with restoration of MCF-7 ADR cells sensitivity to DOX. As a result, the released DOX and SO₂ showed synergistic therapeutic effect against MCF-7 ADR cells. In vivo antitumor evaluation further indicated that, compared with free DOX, the DOX-loaded nanoparticles exhibited better antitumor effect in a MCF-7 ADR-xenografted nude mice model while had lower system toxicity. Overall, we demonstrated, for the first time, that a SO₂ polymer prodrug, acting as a stimuli-responsive nanocarrier to codeliver DOX, can efficiently inhibit the proliferation of MDR tumor cells, which may offer a new weapon for combating MDR in cancer therapy.

Ambient air pollution and daily hospital admissions for mental disorders in Shanghai, China

Few studies have investigated the associations between ambient air pollution and mental disorders (MDs), especially in developing countries. We conducted a time-series study to explore the associations between six criteria air pollutants and daily hospital admissions for MDs in Shanghai, China, from 2013 to 2015. The MDs data were derived from the Shanghai Health Insurance System. We used over-dispersed, generalized additive models to estimate the associations after controlling for time trend, weather conditions, day of the week, and holidays. In addition, we evaluated the effect of modification by age, sex, and season. A total of 39,143 cases of hospital admissions for MDs were identified during the study period. A 10-μg/m³ increase in 2-day, moving-average concentration of inhalable particulate matter, sulfur dioxide (SO₂), and carbon monoxide was significantly associated with increments of 1.27% [95% confidence interval (CI): 0.28%, 2.26%], 6.88% (95% CI, 2.75%, 11.00%), and 0.16% (95% CI: 0.02%, 0.30%) in daily hospital admissions for MDs, respectively. We observed positive but insignificant associations of fine particulate matter, nitrogen dioxide and ozone. The estimated association of SO₂ was relatively robust to the adjustment of simultaneous exposure to other pollutants. We found generally stronger associations of air pollutants with MDs in warm seasons than in cool seasons. There were no significant differences in the associations between different sex and age groups. This study suggested that short-term exposure to air pollution, especially to sulfur dioxide, was associated with increased risk of hospital admissions for MDs in Shanghai, China.

The Effects of Formaldehyde on Cytochrome P450 Isoform Activity in Rats

Formaldehyde (FA) is an occupational and indoor pollutant. Long-term exposure to FA can irritate the respiratory mucosa, with potential carcinogenic effects on the airways. The effects of acute FA poisoning on the activities of CYP450 isoforms CYP1A2, CYP2C11, CYP2E1, and CYP3A2 were assessed by determining changes in the pharmacokinetic parameters of the probe drugs phenacetin, tolbutamide, chlorzoxazone, and testosterone, respectively. Rats were randomly divided into three groups: control, low FA dose (exposure to 110 ppm for 2 h for 3 days), and high FA dose (exposure to 220 ppm for 2 h for 3 days). A mixture of the four probe drugs was injected into rats and blood samples were taken at a series of time points. Plasma concentrations of the probe drugs were measured by HPLC. The pharmacokinetic parameters t1/2, AUC(0-t), and Cmax of tolbutamide, chlorzoxazone, and testosterone increased significantly in the high dose versus control group (P < 0.05), whereas the CL of chlorzoxazone and testosterone decreased significantly (P < 0.05). However, t1/2, AUC(0-t), and Cmax of phenacetin decreased significantly (P < 0.05), whereas the CL of phenacetin increased significantly (P < 0.05) compared to controls. Thus, acute FA poisoning suppressed the activities of CYP2C11, CYP2E1, and CYP3A2 and induced the activity of CYP1A2 in rats. And the change of CYP450 activity caused by acute FA poisoning may be associated with FA potential carcinogenic effects on the airways.

Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus L.), protects rat tissues against oxidative damage after acute ethanol administration

Ethanol-mediated free radical generation is directly involved in alcoholic liver disease. In addition, chronic alcohol bingeing also induces pathological changes and dysfunction in multi-organs. In the present study, the protective effect of xanthohumol (XN) on ethanol-induced damage was evaluated by determining antioxidative parameters and stress oxidative markers in liver, kidney, lung, heart and brain of rats. An acute treatment (4 g/kg b.w.) of ethanol resulted in the depletion of superoxide dismutase, catalase and glutathione S-transferase activities and reduced glutathione content. This effect was accompanied by the increased activity of tissue damage marker enzymes (glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and lactate dehydrogenase) and a significant increase in lipid peroxidation and hydrogen peroxide concentrations. Pre-treatment with XN protected rat tissues from ethanol-induced oxidative imbalance and partially mitigated the levels to nearly normal levels in all tissues checked. This effect was dose dependent, suggesting that XN reduces stress oxidative and protects rat tissues from alcohol-induced injury.

Arsenic transformations and biomarkers in meadow voles (Microtus pennsylvanicus) living on an abandoned gold mine site in Montague, Nova Scotia, Canada

Arsenic is one of the most widely encountered environmental contaminants because of a number of anthropogenic sources; in Canada the main anthropogenic release of arsenic is from mine tailings ponds. The present study is part of a series of studies to measure chemical and biological effects of exposure for meadow voles (Microtus pennsylvanicus) living on arsenic contaminated sites. Two additional objectives were addressed in the present study: the effect of higher arsenic concentrations compared with previous studies, and the comparison of chemical speciation and biological effects. To obtain the higher environmental concentrations, specimens were collected from a former gold mining site in Montague, NS that contains highly elevated concentrations of arsenic in soils and plants. Meadow voles were collected and their tissues were analyzed for total arsenic to measure uptake, and arsenic speciation to examine the chemical effects of the high arsenic exposure. In addition to the arsenic analysis, a biomonitoring study was undertaken to examine the sub-cellular effects in meadow voles resulting from the elevated arsenic exposure. Meadow voles living on the contaminated site had substantially higher concentrations of total arsenic than animals from the background (reference) location. The extractable arsenic in internal tissues was present mainly as monomethylarsonic acid (up to 14% of total arsenic). A statistically significant relationship was observed between the reduction of glutathione in vole livers and the increase in liver arsenic concentrations, and micronucleated monochromatic red blood cells were also significantly elevated in voles from the arsenic contaminated site. This is one of the few field studies where sub-cellular effects were observed, and the first to show a co-existence of such effects with relatively high proportions of monomethylarsonic acid in voles living near mine tailings.

Use of biomarkers to show sub-cellular effects in meadow voles (Microtus pennsylvanicus) living on an abandoned gold mine site

Run-off from mine tailings ponds constitutes the main anthropogenic release of arsenic in Canada. As a potential consequence, wildlife not normally exposed to arsenic under other circumstances may receive toxicologically relevant concentrations of arsenic compounds in their food and water. To test this hypothesis, and to determine if arsenic is being transported through trophic levels, the arsenic concentrations in members of a short food chain (soil-plant-meadow vole) were measured. Arsenic concentrations were higher in exposed organisms compared with those from a reference location. However, elevated concentrations of arsenic do not necessarily indicate impact, and consequently a biomonitoring study was undertaken to determine if there were sub-cellular effects of exposure in meadow voles (Microtus pennsylvanicus) as a consequence of arsenic exposure. In this work, adenosine triphosphate (ATP) and liver glutathione (GSH) levels were used as biomarkers of exposure and the frequency of red blood cell micronuclei (mono- and polychromatic) was used as a biomarker of effect. ATP results were not conclusive but there was a statistically significant relationship between a reduction of GSH in vole livers and increased liver arsenic concentrations. A statistically significant relationship was also observed between increased micronucleated monochromatic red blood cells in voles from arsenic contaminated sites compared to a background location. The results of the GSH and monochromatic red blood cell investigations suggest that there are possible sub-cellular effects on these voles as a consequence of dietary arsenic exposure. This is the first field study in which such effects have been observed in voles living near mine tailings.

SO(2) inhalation induces protein oxidation, DNA-protein crosslinks and apoptosis in rat hippocampus

Previous studies provide evidence for the possible neurotoxicity of SO(2), but little information is available about its mechanisms. In the present study, SO(2) inhalation-induced effects on the protein oxidation, DNA-protein crosslinks and apoptosis in rat hippocampus were studied, by exposing Wistar rats to SO(2) at 14, 28 and 56mg/m(3). The results indicate that the protein carbonyl content, an indicator of protein oxidation, and DNA-protein crosslink coefficient were significantly augmented with concentration-dependent properties. In addition, SO(2) inhalation at all concentrations tested caused the increases of caspase-3 activity and number of TUNEL positive staining neuron and the statistical difference was observed after 28 and 56mg/m(3) exposure, suggesting the occurrence of apoptosis. The results imply that attacking protein, nucleic acids and lipids by free radicals, generated via SO(2) derivatives in vivo, is one of the main mechanisms for SO(2)-induced injuries in central neuronal system.

Delayed rectifier potassium channels are involved in SO2 derivative-induced hippocampal neuronal injury

Recent studies implicate the possible neurotoxicity of SO(2), however, its mechanisms remain unclear. In the present study, we investigated SO(2) derivative-induced effect on delayed rectifier potassium channels (I(K)) and cellular death/apoptosis in primary cultured hippocampal neurons. The results demonstrate that SO(2) derivatives (NaHSO(3) and Na(2)SO(3), 3:1M/M) effectively augmented I(K) and promoted the activation of delayed rectifier potassium channels. Also, SO(2) derivatives increased neuronal death percentage and contributed to the formation of DNA ladder in concentration-dependent manners. Interestingly, the neuronal death and DNA ladder formation, caused by SO(2) derivatives, could be attenuated by the delayed rectifier potassium channel blocker (tetraethylammonium, TEA), but not by the transient outward potassium channel blocker (4-aminopyridine, 4-AP). It implies that stimulating delayed rectifier potassium channels were involved in SO(2) derivative-caused hippocampal neuronal insults, and blocking these channels might be one of the possibly clinical treatment for SO(2)-caused neuronal dysfunction.

Protective effects of salicylic acid and vitamin C on sulfur dioxide-induced lipid peroxidation in mice

The antioxidant effects of exogenous salicylic acid (SA) and vitamin C (Vit C) on the oxidative stress induced by 56 mg/m(3) of sulfur dioxide (SO2) in mouse livers and brains were investigated. The exposure of SO2 caused significant elevation of thiobarbituric acid-reactive substance (TBARS) levels and reduction of enzyme activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in brain and liver, accompanied by a decrease in relative growth rate, when compared with controls. Application of moderate concentrations of SA and Vit C markedly reduced the SO2-induced elevation of TBARS levels, with 5.5 mg/kg SA or 200 mg/kg Vit C being most effective. In contrast to the decrease of TBARS levels, the levels of SOD, POD, and CAT in liver and brain were significantly increased in comparison with controls. The polyacrylamide gel electrophoresis (PAGE) of total liver proteins showed that the SO2 inhalation caused a 30-kD protein band disappearance compared with the control. However, the band remained unchanged in the samples treated with 5.5 and 8.25 mg/kg SA or 100, 200, and 400 mg/kg Vit C. Therefore, this protein band may serve as a marker for the damage induced by SO2 and an additional basis for drug screening and selection.

Effects of SO2 derivatives on sodium currents in acutely isolated rat hippocampal lead-exposed neurons

In this study, the effects of acute SO2 derivatives and chronic lead exposure together on sodium currents (I(Na)) were investigated in acutely isolated rat hippocampal neurons by using the whole-cell patch clamp techniques. We found that chronic lead exposure hardly reduced the amplitudes of I(Na). In the normal condition, sodium current started to appear at around -70 mV, and reached the peak current at around -40 mV. After chronic lead exposure, the data changed to -70 and -30 mV. After adding SO2 derivatives, the data changed to -80 and -40 mV, respectively. SO2 derivatives caused a significant increase of I(Na) in hippocampal chronic-lead exposed neurons. Chronic lead exposure induced a right shift of the activation curve and a left shift of the inactivation curve of sodium channels. SO2 derivatives caused negative shifts of the activation and inactivation curves of I(Na) in hippocampal chronic-lead exposed neurons. Lead exposure put off the time reaching the peak of I(Na) activation. SO2 derivatives increased the time constants of inactivation after lead exposure. The interaction of lead and SO2 derivatives with voltage-dependent sodium channels may lead to changes in electrical activity and contribute to worsening the neurotoxicological damage.

Effect of sulfur dioxide inhalation on CYP2B1/2 and CYP2E1 in rat liver and lung

Sulfur dioxide (SO2) is a ubiquitous air pollutant, present in low concentrations in the urban air and in higher concentrations in the working environment. In this study, we investigated the effects of inhaled SO2 on the O-dealkylase of pentoxyresorufin (PROD) and p-nitrophenol hydroxylases (p-NP) activities and mRNA levels of CYP2B1/2 and CYP2E1 in the lung and liver of Wistar rats. Male Wistar rats were housed in exposure chambers and treated with 14.11 +/- 1.53, 28.36 +/- 2.12, and 56.25 +/- 4.28 mg/m3 SO2 for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. The mRNAs of CYP2B1/2 and -2E1 were analyzed in livers and lungs by using reverse-transcription polymerase chain reaction (RT-PCR). Our results showed that the PROD activities and mRNA of CYP2B1/2 were decreased in livers and lungs of rats exposed to SO2. The p-NP activities and mRNA of CYP2E1 were decreased in lungs but not in livers of rats exposed to SO2. Total liver microsomal cytochrome P-450 (CYP) contents were diminished in SO2-exposed rats. These results lead to two conclusions: (1) SO2 exposure can suppress CYP2B1/2 and CYP2E1 in lungs and CYP2B1/2 in livers of rats, thus modifying the liver and lung toxication/detoxication potential, and (2) the total liver microsomal CYP contents were diminished, although the activity and mRNA expression of CYP2E1 in rat livers were not affected by SO2 exposure.

Protein oxidation and DNA-protein crosslink induced by sulfur dioxide in lungs, livers, and hearts from mice

In this article, protein oxidative damage and DNA-protein crosslinks (DPC) induced by sulfur dioxide (SO(2)) in lungs, livers, and hearts of mice were studied. The protein carbonyl (PCO) content was measured using spectrophotometric DNPH assay to reflect the degree of protein oxidative damage, and the DPC coefficient was measured by using a KCl-sodium dodecyl sulfate (SDS) assay to show the degree of DNA damage in lungs, livers, and hearts from mice exposed to SO(2) at various concentrations (0, 14, 28, and 56 mg-m(- 3)) for 6 h per day for 7 days. The results indicate that SO(2) caused an increase of PCO and DPC level in all organs tested from mice in a concentration-dependent manner. The concentration-response relationships in all organs tested of both female and male mice could be fitted well with monolinear regression equations. The adjusted coefficient R squared of all equations is more than 0.9. These results lead to a conclusion that SO(2) may cause an increase of protein oxidation damage and DNA-protein crosslinking in lungs, livers, and hearts from mice. The rank order of absolute increase in PCO contents and DPC coefficient in three organs from mice compared with controls was lung > liver > heart. Our results also indicated the regulation of PCO and that of DPC induced by SO(2) were conformed to each other; this implies that the protein oxidative damage may be associated with the emergence of DPC.

The valuation of health effects caused by stationary sources-related SO2 emissions: the adaptation of impact pathway approach in Taiwan

This paper presents the externalities of sulfur dioxide (SO(2)) in the Taichung metropolitan, Taiwan. The human effects of SO(2) from stationary sources are a key element for local air quality management. A methodology to evaluate those effects in monetary term had been adapted and applied. This method was modified from the EU-based impact pathway approach link to the skill of geographic information systems. The studied area was divided into 66 districts and the quantity of SO(2) was allocated to each district. Then, the ambient concentration of SO(2) was estimated by using the ordinary kriging method. A risk analysis was employed to characterize the health impacts caused by SO(2). Finally, a monetary transfer approach based on the European data was conducted to estimate local damage costs per ton of SO(2). Health impacts, especially acute mortality, dominate in term of costs. The calculation showed that damage costs ranged from 0.56 to 7.38 USD/kg SO(2) based on the 2002 emission data. The results could be used in the internalization of SO(2) externalities and management of the stationary sources in the studied area. This paper also concludes that the externalities caused by stationary-related SO(2) emissions are some 28.5 million US dollars in Taichung metropolitan (Taiwan) in 2002.

Oxidative damage induced in brains and livers of mice by landfill leachate

The effects of the Xingou municipal landfill leachate on levels of thiobarbituric acid reactive substances (TBARS) and the activities of Cu,Zn-superoxide dismutase (Cu,Zn-SOD), Se-dependent glutathione peroxidase (Se-dependent GPx), and catalase (CAT) were investigated in brains and livers of Kunming albino mice of both sexes, using chemical oxygen demand (COD(Cr)) as a measure of leachate concentration. The results show that leachate caused lipid peroxidation and change of antioxidative status in brains and livers of mice. There was a sex difference in the response of antioxidative status, and female mice were more sensitive than male mice. Exposure to leachate at all concentrations tested caused significant increases of TBARS levels in brains and livers from mice of both sexes. For brains, Cu,Zn-SOD and Se-dependent GPx activities were significantly increased at high concentration (COD(Cr) 240 mg/L) for male mice, but the activities of both antioxidative enzymes were significantly increased at low concentration (COD(Cr) 60 mg/L) and decreased at high concentration (COD(Cr) 240 mg/L) for female mice; CAT activities remained unchanged for male mice and were significantly decreased for female mice at high concentration (COD(Cr) 240 mg/L). For livers, Cu,Zn-SOD and Se-dependent GPx activities were significantly increased at high concentrations (COD(Cr) 120 and 240 mg/L) for male mice, but the activities of both antioxidative enzymes were significantly increased at low concentration (COD(Cr) 30 or 60 mg/L) and decreased at high concentration (COD(Cr) 240 mg/L) for female mice; CAT activities were significantly increased for male mice at all concentrations tested and decreased for female mice at high concentrations (COD(Cr) 120 and 240 mg/L). These results suggest that leachate exposure can cause oxidative damage on brains and livers of mice. The results also suggest that leachate might induce toxicity in mammals by the free-radical-damage mechanism.

Expression of apoptosis-related genes in livers from rats exposed to sulfur dioxide

Sulfur dioxide (SO2) is a ubiquitous air pollutant that is present in low concentrations in the urban air, and in higher concentrations in the working environment. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00+/-1.01, 28.00+/-1.77 and 56.00+/-3.44 mg/m3 SO2 for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. The mRNA and protein levels of three apoptosis-related genes (p53 and bax were promoters of apoptosis, whereas bcl-2 was apoptotic suppressor) were analyzed in livers using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and immunohistochemistry method. The results showed that mRNA levels of p53 and bax were increased in a dose-dependent manner and at the concentrations of 28.00 and 56.00 mg/m3SO2 the increases were significant (for p53: 1.30-fold at 28 mg/m3 and 3.43-fold at 56 mg/m3, for bax: 1.63-fold at 28 mg/m3 and 2.17-fold at 56 mg/m3, respectively), while mRNA levels of bcl-2 were decreased significantly (0.63-fold at 28 mg/m3 and 0.45-fold at 56 mg/m3) in livers of rats exposed to SO2. Dose-dependent increases of p53 and bax proteins in the livers were observed after SO2 inhalation, while decrease of bcl-2 protein levels was obtained using immunohistochemistry method. These results lead to a conclusion that SO2 exposure could change the expression of apoptosis-related genes, and it suggests that SO2 can induce apoptosis in liver of rat and may have relations with some apoptosis-related diseases. It is critical for our understanding of the mechanisms of SO2 toxicity and helpful for the therapeutic intervention to elucidate the expression pattern of those factors involved in apoptosis signaling pathway after SO2 inhalation.

Effect of sulfur dioxide inhalation on CYP1A1 and CYP1A2 in rat liver and lung

Sulfur dioxide (SO2) is a ubiquitous air pollutant, presents in low concentrations in the urban air, and in higher concentrations in the working environment. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00+/-1.53, 28.00+/-2.12 and 56.00+/-4.28 mg/m3 SO2 for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. Highly specific substrates were used as probes of cytochrome P4501A1 (CYP1A1) and cytochrome P4501A2 (CYP1A2). The mRNA levels of CYP1A1 and 1A2 were analyzed in livers and lungs by using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay. Our results showed that the activities and mRNA levels of P450 were decreased in livers and lungs of rats exposed to SO2. In the liver, a decrease down to 0.68- and 0.64-fold in the CYP1A1 activity, probed by the O-deethylation of ethoxyresorufin (EROD), was observed at higher dose of SO2 (28 and 56 mg/m3); Similarly, CYP1A1 mRNA levels were reduced in livers of rats exposed to SO2 at 28 and 56 mg/m3. For livers, CYP1A2-mediated methoxyresorufin O-demethylase activity (MROD) was unaltered by SO2 at low concentrations, except for a significant decrease in the rats exposed to SO2 at 56 mg/m3 (0.79-fold); however, SO2 at higher concentrations significantly decreased levels of CYP1A2 (28 and 56 mg/m3) (p<0.05). Significant inhibition of both EROD and MROD was observed in lungs of rats exposed to SO2 at 28 and 56mg/m3. CYP1A1 activity was repressed 0.62- and 0.53-fold, while CYP1A2 activity was reduced to 0.74- and 0.55-fold in lungs, respectively. SO2 at higher concentrations (28 and 56 mg/m3) decreased significantly pulmonary CYP1A1 and 1A2 mRNA levels relative to control animals. Furthermore, the decreases of activities and mRNA levels of these P450 enzymes caused by SO2 at different concentrations in lungs and livers of rats followed linear dose-response curves. These results lead to the conclusion that SO2 exposure can reduce CYP1A1 and 1A2 in lungs and livers of rats and ROS and/or cytokines might act as mediators of this effect according to previous studies performed in mice. Reduction of hepatic and pulmonary CYPlAl and lA2 expression during SO2 exposure may be part of an adaptive response by the liver and lung to minimize cell damage.

Oxidation damage of sulfur dioxide on testicles of mice

The effects of sulfur dioxide (SO2) on levels of thiobarbituric acid reactive substances (TBARS), levels of reduced glutathione (GSH), and the activities of Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were investigated in testicles of Kunming albino male mice. SO2 at different concentrations (22, 56, and 112 mg/m3) was administered to animals of SO2 groups in different exposure chambers for 6 h/day for 7 days, while control groups were exposed to filtered air under the same conditions. Our results show that SO2 caused lipid peroxidation and changes in antioxidative status in testicles of mice. Exposure to SO2 at all concentrations tested significantly increased TBARS levels in testicles of mice. SO2 at all concentrations tested tended to decrease activities of SOD and GPx enzymes and levels of GSH relative to control animals, but only the decreases in SOD and GPx activities caused by SO2 exposures of higher concentrations were statistically significant. SO2 at all concentrations tested tended to increase activities of CAT relative to control animals, but the increases of CAT activities caused by SO2 exposures of low concentrations (22 and 56 mg/m3) were statistically significant. These results lead to the conclusion that SO2 exposure can cause oxidative damage to testicles of male mice, and SO2 is a toxin to the reproductive system of mammals, not only to the respiratory system. Further work is required to understand the toxicological role of SO2 in reproduction organs or even sperm from humans and animals.

Status of antioxidant defense system in chromium-induced Swiss mice tissues

Based on epidemiological studies, chromium(VI) compounds are considered as more toxic and carcinogenic than chromium(III) compounds. The deleterious effects of chromium(VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. The present study, describes the cytotoxic effects of chromium trioxide, a well-known chromium(VI) compound in three tissues (liver, kidney, lungs) of male Swiss mice during post-treatment phase (5th-8th week after treatment). Lipid peroxidation, an index of oxidative stress, was determined as thiobarbituric acid-reactive substances (TBA-Rs) in mice tissues dosed with a single intraperitoneal injection of chromium trioxide (1mg/kg body weight). Tissue specific and statistically significant increases in TBA-Rs was observed in chromium-treated mice groups compared to controls in all the weeks of post-treatment. Endogenous ascorbic acid (vit-C) content of tissues which happens to be one of the stable antioxidants, declined significantly due to chromium-induction. Activity of antioxidative enzymes like superoxide dismutase (SOD), catalase (CT) and peroxidase (PD) was significantly inhibited among chromium-injected mice groups compared to respective controls. Protective role of ascorbic acid and the antioxidative enzymes in chromium-induced cytotoxicity in mice is discussed.

Modulation of sodium currents in rat dorsal root ganglion neurons by sulfur dioxide derivatives

The effect of sulfur dioxide (SO2) derivatives, a common air pollutant and exists in vivo as an equilibrium between bisulfate and sulfite, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in cultured post-natal dorsal root ganglion (DRG) neurons were studied using the whole cell configuration of patch-clamp technique. SO2 derivatives on two types of sodium currents were either inhibitory or stimulatory depending on the kinetic parameters tested. At a holding potential of -80 mV, SO2 derivatives suppressed TTX-S sodium currents when depolarizing potential was negative to -30 mV and TTX-R sodium currents when negative to -10 mV but they increased them when the depolarizing potential was positive to -30 or -10 mV. SO2 derivatives shifted the conductance-voltage curve for TTX-R sodium currents in the depolarizing direction but had little effect on that for TTX-S sodium currents. The steady-state inactivation curve for TTX-R sodium channel was shifted by SO2 derivatives in the depolarizing direction as that for TTX-S sodium channel. SO2 derivatives changed the reversal potential and increased the maximum conductance of two types of sodium channels. SO2 derivatives postponed the activating time and delayed the inactivation of sodium currents. The results suggest that SO2 derivatives would increase the excitability of neurons and alter the ion selectivity for two types of sodium currents.