Age, gender, and hormonal status modulate the vascular toxicity of the diesel exhaust extract phenanthraquinone

Association between ambient air pollutants and lipid profile: A systematic review and meta-analysis

BACKGROUND

Studies of the effects of atmospheric pollutants on lipid profiles remain inconsistent and controversial.

AIM

The study was aimed to investigate the relationship between the exposure to ambient air pollutants and variations in the blood lipid profiles in the population.

METHODS

A comprehensive search of three different databases (PubMed, Web of Science, and the Cochrane Library) until December 17, 2022, yielded 17 origional studies fulfilling the inclusion criteria for a meta-analysis. Aggregate effect measures and 95% confidence intervals (95% CI) for the relevant ambient air pollutants were deduced employing random effects models.

RESULTS

The collective meta-analysis indicated that long-term exposure to PM₁, PM_2.5, PM₁₀ and CO showed a substantial correlation with TC (PM₁: β = 2.04, 95%CI = 0.15-3.94; PM_2.5: β = 1.11, 95%CI = 0.39-1.84; PM₁₀: β = 1.70, 95%CI = 0.67-2.73; CO: β = 0.08, 95%CI = 0.06-0.10), PM₁₀ exhibited a significant association with TG (β = 0. 537,95% CI = 0.09-0.97), whereas HDL-C demonstrated notable relationships with PM₁, PM₁₀, SO₂ and CO (PM₁: β = -2.38, 95%CI = -4.00 to -2.76; PM₁₀: β = -0.77, 95%CI = -1.33 to -0.21; SO₂: β = -0.91, 95%CI = -1.73 to -0.10; CO: β = -0.03, 95%CI = -0.05 to 0.00). PM_2.5, PM₁₀ also showed significant associations with LDL-C (PM_2.5: β = 1.44 95%CI = 0.48-2.40; PM₁₀: β = 1.62 95%CI = 0.90-2.34). Subgroup analysis revealed significant or stronger correlations predominantly in cohort study designs, with higher male comparisons, and in regions exhibiting elevated contaminant levels.

CONCLUSION

In summary, the analysis substantiates that ambient air pollutants can be recognized as potent contributors to alterations in lipid profiles, particularly particulate pollutants which exert more obvious effects on lipid profiles.

Impact of Ambient Ultrafine Particles on Cause-Specific Mortality in Three German Cities

Rationale: Exposure to ambient air pollution has been associated with adverse effects on morbidity and mortality. However, the evidence for ultrafine particles (UFPs; 10-100 nm) based on epidemiological studies remains scarce and inconsistent. Objectives: We examined associations between short-term exposures to UFPs and total particle number concentrations (PNCs; 10-800 nm) and cause-specific mortality in three German cities: Dresden, Leipzig, and Augsburg. Methods: We obtained daily counts of natural, cardiovascular, and respiratory mortality between 2010 and 2017. UFPs and PNCs were measured at six sites, and measurements of fine particulate matter (PM2.5; ⩽2.5 μm in aerodynamic diameter) and nitrogen dioxide were collected from routine monitoring. We applied station-specific confounder-adjusted Poisson regression models. We investigated air pollutant effects at aggregated lags (0-1, 2-4, 5-7, and 0-7 d after UFP exposure) and used a novel multilevel meta-analytical method to pool the results. Additionally, we assessed interdependencies between pollutants using two-pollutant models. Measurements and Main Results: For respiratory mortality, we found a delayed increase in relative risk of 4.46% (95% confidence interval, 1.52 to 7.48%) per 3,223-particles/cm3 increment 5-7 days after UFP exposure. Effects for PNCs showed smaller but comparable estimates consistent with the observation that the smallest UFP fractions showed the largest effects. No clear associations were found for cardiovascular or natural mortality. UFP effects were independent of PM2.5 in two-pollutant models. Conclusions: We found delayed effects for respiratory mortality within 1 week after exposure to UFPs and PNCs but no associations for natural or cardiovascular mortality. This finding adds to the evidence on the independent health effects of UFPs.

Exploring the impact of particulate matter on mortality in coastal Mediterranean environments

Air pollution is one of the most important problems the world is facing nowadays, adversely affecting public health and causing millions of deaths every year. Particulate matter is a criteria pollutant that has been linked to increased morbidity, as well as all-cause and cause-specific mortality. However, this association remains under-investigated in smaller-size cities in the Eastern Mediterranean, which are also frequently affected by heat waves and dust storms. This study explores the impact of particulate matter with an aerodynamic diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm (PM_2.5) on mortality (all-cause, cardiovascular, respiratory) in two coastal cities in the Eastern Mediterranean; Thessaloniki, Greece and Limassol, Cyprus. Generalized additive Poisson models were used to explore overall and gender-specific associations, controlling for long- and short-term patterns, day of week and the effect of weather variables. Moreover, the effect of different lags, season, co-pollutants and dust storms on primary associations was investigated. A 10 μg/m³ increase in PM_2.5 resulted in 1.10 % (95 % CI: -0.13, 2.34) increase in cardiovascular mortality in Thessaloniki, and in 3.07 % (95 % CI: -0.90, 7.20) increase in all-cause mortality in Limassol on the same day. Additionally, significant positive associations were observed between PM_2.5 as well as PM₁₀ and mortality at different lags up to seven days. Interestingly, an association with dust storms was observed only in Thessaloniki, having a protective effect, while the gender-specific analysis revealed significant associations only for the males in both cities. The outcome of this study highlights the need of city- or county-specific public health interventions to address the impact of climate, population lifestyle behaviour and other socioeconomic factors that affect the exposure to air pollution and other synergistic effects that alter the effect of PM on population health.

Combined oxidant capacity, redox-weighted oxidant capacity and elevated blood pressure: A panel study

BACKGROUND

Evidence is limited on the potential health effects of Ox (sum value) and Oxwt(weighted value), the two surrogates for ozone (O3) and nitrogen dioxides (NO2).

OBJECTIVES

To investigate the impacts of Ox and redox-weighted oxidant capacity (Oxwt) on blood pressure (BP).

METHODS

A panel study was conducted with four repeated follow-up visits among 40 healthy college students in Hefei, Anhui Province, China from August to October, 2021. We measured BP by using an automated sphygmomanometer and obtained hourly data of air pollutants at a nearby site. The sum of O3 and NO2 (Ox) and their weighted average (Oxwt) were obtained as exposure variables. We applied linear mixed-effect models to evaluate the effects of Ox and Oxwton systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP) and pulse pressure (PP).

RESULTS

Totally, 160 pairs of valid BP values were obtained. The 24-h mean levels of Ox and Oxwt were 64.38 μg/m3 and 110.28 μg/m3, respectively. Overall, both Ox and Oxwt were significantly linked with SBP, DBP and MAP at most lag periods, whereas non-significant with PP. A 10-μg/m3 increase in Oxwt at lag 0-24 h was linked to increases of 2.43 mmHg (95% CI: 0.96, 3.91) in SBP, 2.31 mmHg (95% CI: 1.37, 3.26) in DBP and 2.35 mmHg (95% CI: 1.35, 3.36) in MAP, while the corresponding effect estimates for Ox were 1.51 mmHg (95%CI: 0.60, 2.43), 1.43 mmHg (95% CI: 0.85, 2.02) and 1.46 mmHg (95%CI: 0.83, 2.09). In two-pollutant models, our results were almost unchanged after controlling for simultaneous exposure to other pollutants. The effects were more pronounced among males and those with physical activity.

CONCLUSIONS

The findings provide first-hand evidence that short-term exposure to Ox and Oxwt was associated with BP increases in young adults.

Sex-difference in air pollution-related acute circulatory and respiratory mortality and hospitalization

BACKGROUND

Numerous studies have estimated adverse effects of short-term exposure to ambient air pollution on public health. Few have focused on sex-differences, and results have been inconsistent. The purpose of this study was three-fold: to identify sex-differences in air pollution-related health outcomes; to examine sex-differences by cause and season; and to examine time trends in sex-differences.

METHODS

Daily data were collected on circulatory- and respiratory-related mortality (for 29 years) and cause-specific hospitalization (for 17 years) with hourly concentrations of ozone (O3), nitrogen dioxide (NO2), and fine particulate matter (PM2.5). For hospitalization, more specific causes were examined: ischemic heart disease (IHD), other heart disease (OHD), cerebrovascular disease (CEV), chronic lower respiratory diseases (CLRD), and Influenza/Pneumonia (InfPn). Generalized Poisson models were applied to 24 Canadian cities, and the city-specific estimates were combined for nationwide estimates for each sex using Bayesian hierarchical models. Finally, sex-differences were tested statistically based on their interval estimates, considering the correlation between sex-specific national estimates.

RESULTS

Sex-differences were more frequently observed for hospitalization than mortality, respiratory than circulatory health outcomes, and warm than cold season. For hospitalization, males were at higher risk (M > F) for warm season (OHD and InfPn from O3; IHD from NO2; and InfPn from PM2.5), but F > M for cold season (CEV from O3 and OHD from NO2). For mortality, we found F > M only for circulatory diseases from ozone during the warm season. Among the above-mentioned sex-differences, three cases showed consistent time trends over the years: while M > F for OHD from O3 and IHD from NO2, F > M for OHD from NO2.

CONCLUSIONS

We found that sex-differences in effect of ambient air pollution varied over health outcome, cause, season and time. In particular, the consistent trends (either F > M or M > F) across 17 years provide stronger evidence of sex-differences in hospitalizations, and warrant investigation in other populations.

Short-term effect of fine particulate matter and ozone on non-accidental mortality and respiratory mortality in Lishui district, China

Background

In recent years, air pollution has become an imminent problem in China. Few studies have investigated the impact of air pollution on the mortality of the middle-aged and elderly people. Therefore, this study aims to evaluate the impact of PM_2.5 (fine particulate matter) and O₃ (ozone) on non-accidental mortality and respiratory mortality of the middle-aged and elderly people in Lishui District of Nanjing and provide the evidence for potential prevention and control measures of air pollution.

Method

Using daily mortality and atmospheric monitoring data from 2015 to 2019, we applied a generalized additive model with time-series analysis to evaluate the association of PM_2.5 and O₃ exposure with daily non-accidental mortality and respiratory mortality in Lishui District. Using the population attributable fractions to estimate the death burden caused by short-term exposure to O₃ and PM_2.5。.

Result

For every 10 μg/m³ increase in PM_2.5, non-accidental mortality increased 0.94% with 95% confidence interval (CI) between 0.05 and 1.83%, and PM_2.5 had a more profound impact on females than males. For every 10 μg/m³ increase in O₃, respiratory mortality increased 1.35% (95% CI: 0.05, 2.66%) and O₃ had a more profound impact on males than females. Compared with the single pollutant model, impact of the two-pollutant model on non-accidental mortality and respiratory mortality slightly decreased. In summer and winter as opposed to the other seasons, O₃ had a more obvious impact on non-accidental mortality. The population attributable fractions of non-accidental mortality were 0.84% (95% CI:0.00, 1.63%) for PM_2.5 and respiratory mortality were 0.14% (95% CI:0.01, 0.26%) for O₃. For every 10 μg/m³ decrease in PM_2.5, 122 (95% CI: 6, 237) non-accidental deaths could be avoided. For every 10 μg/m³ decrease in O₃, 10 (95% CI: 1, 38) respiratory deaths could be avoided.

Conclusion

PM_2.5 and O₃ could significantly increase the risk of non-accidental and respiratory mortality in the middle-aged and elderly people in Lishui District of Nanjing. Exposed to air pollutants, men were more susceptible to O₃ damage, and women were more susceptible to PM_2.5 damage. Reduction of PM_2.5 and O₃ concentration in the air may have the potential to avoid considerable loss of lives.

Pollutant-sex specific differences in respiratory hospitalization and mortality risk attributable to short-term exposure to ambient air pollution

BACKGROUND

Many studies have reported associations of individual pollutants with respiratory hospitalization and mortality based on different populations, which makes it difficult to directly compare adverse health effects among multiple air pollutants.

OBJECTIVES

The study goal is to compare acute respiratory-related hospitalization and mortality associated with short-term exposure to three ambient air pollutants and analyze differences in health risks by season, age and sex.

METHODS

Hourly measurements of air pollutants (ozone, NO₂, PM_2.5) and temperature were collected from ground-monitors for 24 cities along with daily hospitalization (1996-2012) and mortality (1984-2012) data. National associations between air pollutant and health outcome were estimated for season (warm, cold vs. year-round), age (base ≥ 1, seniors > 65), and sex (females ≥ 1 and males ≥ 1) using Bayesian hierarchical models.

RESULTS

Overall, the three air pollutants were significantly associated with acute respiratory health outcomes at different lag-days. For respiratory hospitalization, the increased risks in percent changes with 95% posterior intervals for a 10-unit increase in each pollutant were: ozone (lag1, 0.7% (0.4, 0.9)), NO₂ (lag0, 0.7% (0.1, 1.4)), and PM_2.5 (lag1, 1.3% (0.7, 1.9)). For respiratory mortality: ozone (lag2, 1.2% (0.4, 1.9)), NO₂ (lag1, 2.1% (0.6, 3.5)), and PM_2.5 (lag1, 0.6% (-1.0, 2.2)). While some differences in risk were observed by season and age group, sex-specific differences were more pronounced. Compared with males, females had a higher respiratory mortality risk (1.8% (0.6, 2.9) vs 0.5% (-0.3, 1.3)) from ozone, a higher respiratory hospitalization risk (0.9% (0.0, 1.8) vs 0.6% (-0.3, 1.4)) but lower mortality risk (1.4% (-1.0, 3.7) vs 2.2% (0.4, 4.0)) from NO₂, and a lower hospitalization risk (0.7% (-0.2, 1.7) vs 1.8% (1.0, 2.6)) from PM_2.5.

CONCLUSION

This study reports significant health effects of short-term exposure to three ambient air pollutants on respiratory hospitalization (ozone≈NO₂ < PM_2.5 per-10 unit; ozone>NO₂ ≈ PM_2.5 per-IQR) and mortality (ozone≈NO₂ > PM_2.5) in Canada. Pollutant-sex-specific differences were found, but inconclusive due to limited biological and physiological explanations. Further studies are warranted to understand the pollutant-sex specific differences.

Comparison of hospitalization and mortality associated with short-term exposure to ambient ozone and PM2.5 in Canada

BACKGROUND

Hospitalization and mortality (H-M) have been linked to air pollution separately. However, previous studies have not adequately compared whether air pollution is a stronger risk factor for hospitalization or mortality. This study aimed to investigate differences in H-M risk from short-term ozone and PM_2.5 exposures, and determine whether differences are modified by season, age, and sex.

METHODS

Daily ozone, PM_2.5, temperature, and all-cause H-M counts (ICD-10, A00-R99) were collected for 22-24 Canadian cities for up to 29 years. Generalized additive Poisson models were employed to estimate associations between each pollutant and health outcome, which were compared across season (warm, cold, or year-round), age (all ages or seniors > 65), and sex.

RESULTS

Overall, ozone and PM_2.5 showed higher season-specific risk of mortality than hospitalization: warm-season ozone: 0.54% (95% credible interval, 0.20, 0.85) vs. 0.14% (0.02, 0.27) per 10 ppb; and year-round PM_2.5: 0.90% (0.33, 1.41) vs. 0.29% (0.03, 0.56) per 10 μg/m³. While age showed little H-M difference, sex appeared to be a modifier of H-M risk. While females had higher mortality risk, males had higher hospitalization risk: for females, ozone 0.87% (0.36, 1.35) vs. -0.03% (-0.18, 0.11) and PM_2.5 1.19% (0.40, 1.90) vs. 0.19% (-0.10, 0.47); and for males ozone 0.20% (-0.28, 0.65) vs. 0.35% (0.18, 0.51).

CONCLUSION

This study found H-M differences attributable to ozone and PM_2.5, suggesting that both are stronger risk factors for mortality than hospitalization. In addition, there were clear H-M differences by sex: specifically, females showed higher mortality risk and males showed higher hospitalization risk.

Bone Marrow Microvasculature

The skeleton is highly vascularized due to the various roles blood vessels play in the homeostasis of bone and marrow. For example, blood vessels provide nutrients, remove metabolic by-products, deliver systemic hormones, and circulate precursor cells to bone and marrow. In addition to these roles, bone blood vessels participate in a variety of other functions. This article provides an overview of the afferent, exchange and efferent vessels in bone and marrow and presents the morphological layout of these blood vessels regarding blood flow dynamics. In addition, this article discusses how bone blood vessels participate in bone development, maintenance, and repair. Further, mechanical loading-induced bone adaptation is presented regarding interstitial fluid flow and pressure, as regulated by the vascular system. The role of the sympathetic nervous system is discussed in relation to blood vessels and bone. Finally, vascular participation in bone accrual with intermittent parathyroid hormone administration, a medication prescribed to combat age-related bone loss, is described and age- and disease-related impairments in blood vessels are discussed in relation to bone and marrow dysfunction. © 2020 American Physiological Society. Compr Physiol 10:1009-1046, 2020.

The role of sex in particle-induced inflammation and injury

The use of engineered nanomaterials within various applications such as medicine, electronics, and cosmetics has been steadily increasing; therefore, the rate of occupational and environmental exposures has also increased. Inhalation is an important route of exposure to nanomaterials and has been shown to cause various respiratory diseases in animal models. Human lung disease frequently presents with a sex/gender-bias in prevalence or severity, but investigation of potential sex-differences in the adverse health outcomes associated with nanoparticle inhalation is greatly lacking. Only ~20% of basic research in the general sciences use both male and female animals and a substantial percentage of these do not address differences between sexes within their analyses. This has prevented researchers from fully understanding the impact of sex-based variables on health and disease, particularly the pathologies resulting from the inhalation of particles. The mechanisms responsible for sex-differences in respiratory disease remain unclear, but could be related to a number of variables including sex-differences in hormone signaling, lung physiology, or respiratory immune function. By incorporating sex-based analysis into respiratory nanotoxicology and utilizing human data from other relevant particles (e.g., asbestos, silica, particulate matter), we can improve our understanding of sex as a biological variable in nanoparticle exposures. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Progressive ossification of the bone marrow vasculature with advancing age corresponds with reduced red blood cell count and percentage of circulating lymphocytes in male Fischer-344 rats

OBJECTIVE

Assess the link between bone marrow blood vessel ossification, Tb. and cortical bone, and hematological parameters across the lifespan in rats.

METHODS

Right femora and whole blood samples were taken from male Fischer-344 rats at 1, 6, 12, 18 and 24 months. Femora were scanned by micro-computed tomography (MicroCT) to determine bone marrow blood vessel ossification (ie, ossified vessel volume [OsVV], ossified vessel thickness (OsV.Th), ossified vessel density (OsV density), and structural model index [SMI]). Bone microarchitecture (ie, bone volume [BV/TV], trabecular thickness, trabecular number, and trabecular separation), density and SMI, and cortical bone parameters (ie, cortical shell thickness, porosity, and density) were also determined by MicroCT. Complete blood counts with differentials were conducted.

RESULTS

Ossified vessel volume increased throughout the lifespan, coinciding with reduced trabecular BV/TV and cortical shell thickness at 24 months. Many of the hematological parameters were unchanged (ie, white blood cells, lymphocyte number) or increased (monocyte number, percent monocyte, granulocyte number, percent granulocyte, hemoglobin, hematocrit, mean corpuscular hemoglobin concentration, red blood cell distribution width, platelet, mean platelet volume) with advancing age; however, red blood cells (RBC) and percent lymphocytes (LY%) were reduced at 24 months. In addition, OsV density was similar to trabecular bone density.

CONCLUSIONS

Declines in trabecular BV/TV, cortical shell thickness, RBC, and LY% with advanced age coincided with augmented ossification of bone marrow blood vessels.

Short-term intermittent PTH 1-34 administration and bone marrow blood vessel ossification in Mature and Middle-Aged C57BL/6 mice

Intermittent parathyroid hormone (PTH) administration augments bone and progressive bone marrow blood vessel (BMBV) ossification occurs with advancing age. Since intermittent PTH administration augments bone, it may also serve to increase BMBV ossification. We assessed the influence of 5- and 10-days of intermittent PTH 1–34 administration on trabecular and cortical bone and BMBV ossification in mature (6–8 mon; n = 30) and middle-aged (10–12 mon; n = 30) male and female C57BL/6 mice. Mice were divided accordingly: control (CON) and 5-days (5dPTH) and 10-days (10dPTH) of PTH. Mice were given PBS (50 μl) or PTH 1–34 (43 μg/kg/d) for 5- and 10-consecutive days. Trabecular bone microarchitecture (i.e., BV/TV [%], Tb.Th [μm], Tb.N [/mm], and Tb.Sp [μm]) was assessed in the distal femoral metaphysis and cortical bone parameters (i.e., Ct.Th [μm] and CSMI [mm⁴]) at the femoral mid-shaft. BMBV ossification (i.e., ossified vessel volume [OsVV, %] and ossified vessel thickness [OsV.Th, μm]) was assessed in the medullary cavity of the femoral shaft. All parameters were determined by μCT. At this sample size, no gender-related differences were observed so female and male data were pooled. There were no main effects nor interactions for trabecular microarchitecture and Ct.Th. However, CSMI was larger (p < 0.05) in Middle-Age vs. Mature and larger (p < 0.05) in CON and 10dPTH vs. 5dPTH. OsVV tended (p = 0.057) to be higher (0.18 ± 0.04% vs. 0.09 ± 0.02%, respectively) and OsV.Th was higher (p < 0.05; 17.4 ± 1.6 μm vs. 12.1 ± 1.4 μm, respectively) in Middle-Aged vs. Mature mice. OsVV was not altered, but ossified vessels tended (p = 0.08) to be thicker in 10dPTH (17.6 ± 2.0 μm) vs. CON (12.5 ± 1.7 μm). No interactions were observed for OsVV and OsV.Th. In conclusion, this is the first report of ossified BMBV in C57BL/6 mice. The increased OsV.Th in Middle-Aged mice coincides with previous reports of increased OsVV in aged rats. The tendency of augmented OsV.Th in 10dPTH suggests that this treatment may ultimately impair the patency of bone marrow blood vessels.

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Bone marrow blood vessel (BMBV) ossification occurs in rats and humans.

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This is the first report of BMBV ossification in Mature and Middle-Aged mice.

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Intermittent PTH administration tended to thicken ossified BMBV.

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PTH treatment may ultimately impact the patency of bone marrow blood vessels.

In Vitro and In Vivo Experimental Studies of PM2.5 on Disease Progression

Air pollution is a very critical issue worldwide, particularly in developing countries. Particulate matter (PM) is a type of air pollution that comprises a heterogeneous mixture of different particle sizes and chemical compositions. There are various sources of fine PM (PM2.5), and the components may also have different effects on people. The pathogenesis of PM2.5 in several diseases remains to be clarified. There is a long history of epidemiological research on PM2.5 in several diseases. Numerous studies show that PM2.5 can induce a variety of chronic diseases, such as respiratory system damage, cardiovascular dysfunction, and diabetes mellitus. However, the epidemiological evidence associated with potential mechanisms in the progression of diseases need to be proved precisely through in vitro and in vivo investigations. Suggested mechanisms of PM2.5 that lead to adverse effects and chronic diseases include increasing oxidative stress, inflammatory responses, and genotoxicity. The aim of this review is to provide a brief overview of in vitro and in vivo experimental studies of PM2.5 in the progression of various diseases from the last decade. The summarized research results could provide clear information about the mechanisms and progression of PM2.5-induced disease.

Cytotoxicity of Air Pollutant 9,10-Phenanthrenequinone: Role of Reactive Oxygen Species and Redox Signaling

Atmospheric pollution has been a principal topic recently in the scientific and political community due to its role and impact on human and ecological health. 9,10-phenanthrenequinone (9,10-PQ) is a quinone molecule found in air pollution abundantly in the diesel exhaust particles (DEP). This compound has studied extensively and has been shown to develop cytotoxic effects both in vitro and in vivo. 9, 10-PQ has been proposed to play a critical role in the development of cytotoxicity via generation of reactive oxygen species (ROS) through redox cycling. This compound also reduces expression of glutathione (GSH), which is critical in Phase II detoxification reactions. Understanding the underlying cellular mechanisms involved in cytotoxicity can allow for the development of therapeutics designed to target specific molecules significantly involved in the 9,10-PQ-induced ROS toxicity. This review highlights the developments in the understanding of the cytotoxic effects of 9, 10-PQ with special emphasis on the possible mechanisms involved.

Global association between ambient air pollution and blood pressure: A systematic review and meta-analysis

Although numerous studies have investigated the association of ambient air pollution with hypertension and blood pressure (BP), the results were inconsistent. We performed a comprehensive systematic review and meta-analysis of these studies. Seven international and Chinese databases were searched for studies examining the associations of particulate (diameter<2.5 μm (PM_2.5), 2.5-10 μm (PM_2.5-10) or >10 μm (PM₁₀)) and gaseous (sulfur dioxide (SO₂), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), ozone (O₃), carbon monoxide (CO)) air pollutants with hypertension or BP. Odds ratios (OR), regression coefficients (β) and their 95% confidence intervals were calculated to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and meta-regression analysis were also conducted. The overall meta-analysis showed significant associations of long-term exposures to PM_2.5 with hypertension (OR = 1.05), and of PM₁₀, PM_2.5, and NO₂ with DBP (β values: 0.47-0.86 mmHg). In addition, short-term exposures to four (PM₁₀, PM_2.5, SO₂, NO₂), two (PM_2.5 and SO₂), and four air pollutants (PM₁₀, PM_2.5, SO₂, and NO₂), were significantly associated with hypertension (ORs: 1.05-1.10), SBP (β values: 0.53-0.75 mmHg) and DBP (β values: 0.15-0.64 mmHg), respectively. Stratified analyses showed a generally stronger relationship among studies of men, Asians, North Americans, and areas with higher air pollutant levels. In conclusion, our study indicates a positive association between ambient air pollution and increased BP and hypertension. Geographical and socio-demographic factors may modify the pro-hypertensive effects of air pollutants.

Intermittent PTH 1-34 administration improves the marrow microenvironment and endothelium-dependent vasodilation in bone arteries of aged rats

Inflammation coincides with diminished marrow function, vasodilation of blood vessels, and bone mass. Intermittent parathyroid hormone (PTH) administration independently improves marrow and vascular function, potentially impacting bone accrual. Currently, the influence of marrow and intermittent PTH administration on aged bone blood vessels has not been examined. Vasodilation of the femoral principal nutrient artery (PNA) was assessed in the presence and absence of marrow. Furthermore, we determined the influence of PTH 1-34 on 1) endothelium-dependent vasodilation and signaling pathways [i.e., nitric oxide (NO) and prostacyclin (PGI₂)], 2) endothelium-independent vasodilation, 3) cytokine production by marrow cells, and 4) bone microarchitecture and bone static and dynamic properties. Young (4-6 mo) and old (22-24 mo) male Fischer-344 rats were treated with PTH 1-34 or a vehicle for 2 wk. In the absence and presence of marrow, femoral PNAs were given cumulative doses of acetylcholine, with and without the NO and PGI₂ blockers, and diethylamine NONOate. Marrow-derived cytokines and bone parameters in the distal femur were assessed. Exposure to marrow diminished endothelium-dependent vasodilation in young rats. Reduced bone volume and NO-mediated vasodilation occurred with old age and were partially reversed with PTH. Additionally, PTH treatment in old rats restored endothelium-dependent vasodilation in the presence of marrow and augmented IL-10, an anti-inflammatory cytokine. Endothelium-independent vasodilation was unaltered, and PTH treatment reduced osteoid surfaces in old rats. In conclusion, the marrow microenvironment reduced vascular function in young rats, and PTH treatment improved the marrow microenvironment and vasodilation with age. NEW & NOTEWORTHY This study investigated the influence of the marrow microenvironment on bone vascular function in young and old rats. An inflamed marrow microenvironment may reduce vasodilator capacity of bone blood vessels, diminishing delivery of blood flow to the skeleton. In young rats, the presence of the marrow reduced vasodilation in the femoral principal nutrient artery (PNA). However, intermittent parathyroid hormone administration (i.e., a treatment for osteoporosis) improved the marrow microenvironment and vasodilator capacity in old PNAs.

Mechanical, hormonal and metabolic influences on blood vessels, blood flow and bone

Bone tissue is highly vascularized due to the various roles bone blood vessels play in bone and bone marrow function. For example, the vascular system is critical for bone development, maintenance and repair and provides O₂, nutrients, waste elimination, systemic hormones and precursor cells for bone remodeling. Further, bone blood vessels serve as egress and ingress routes for blood and immune cells to and from the bone marrow. It is becoming increasingly clear that the vascular and skeletal systems are intimately linked in metabolic regulation and physiological and pathological processes. This review examines how agents such as mechanical loading, parathyroid hormone, estrogen, vitamin D and calcitonin, all considered anabolic for bone, have tremendous impacts on the bone vasculature. In fact, these agents influence bone blood vessels prior to influencing bone. Further, data reveal strong associations between vasodilator capacity of bone blood vessels and trabecular bone volume, and poor associations between estrogen status and uterine mass and trabecular bone volume. Additionally, this review highlights the importance of the bone microcirculation, particularly the vascular endothelium and NO-mediated signaling, in the regulation of bone blood flow, bone interstitial fluid flow and pressure and the paracrine signaling of bone cells. Finally, the vascular endothelium as a mediator of bone health and disease is considered.

Gestational nanomaterial exposures: microvascular implications during pregnancy, fetal development and adulthood

Air pollution particulate matter and engineered nanomaterials are encompassed in the broad definition of xenobiotic particles. While the effects of perinatal air pollution exposure have been investigated, elucidation of outcomes associated with nanomaterial exposure, the focus of this review, is still in its infancy. As the potential uses of nanomaterials, and therefore exposures, increase exponentially so does the need for thorough evaluation. Up to this point, the majority of research in the field of cardiovascular nanotoxicology has focused on the coronary and vascular reactions to pulmonary exposures in young adult, healthy, male models; however, as intentional and unintentional contacts persist, the non-pulmonary risks to under-represented populations become a critical concern. Development of the maternal-fetal circulation during successful mammalian gestation is one of the most unusual complex, dynamic, and acutely demanding physiological systems. Fetal development in a hostile gestational environment can lead to systemic alterations, which may encourage adult disease. Therefore, the purpose of this review is to highlight the few knowns associated with gestational engineered nanomaterial exposure segmented by physiological periods of development or systemic targets: preconception and maternal, gestational, fetal and progeny (Abstract figure). Overall, the limited studies currently available provide compelling evidence of maternal, fetal and offspring dysfunctions after engineered nanomaterial exposure. Understanding the mechanisms associated with these multigenerational effects may allow pregnant women to safely reap the benefits of nanotechnology-enabled products and assist in the implementation of exposure controls to protect the mother and fetus allowing for development of safety by design for engineered nanomaterials.

Microvascular and mitochondrial dysfunction in the female F1 generation after gestational TiO2 nanoparticle exposure

Due to the ongoing evolution of nanotechnology, there is a growing need to assess the toxicological outcomes in under-studied populations in order to properly consider the potential of engineered nanomaterials (ENM) and fully enhance their safety. Recently, we and others have explored the vascular consequences associated with gestational nanomaterial exposure, reporting microvascular dysfunction within the uterine circulation of pregnant dams and the tail artery of fetal pups. It has been proposed (via work derived by the Barker Hypothesis) that mitochondrial dysfunction and subsequent oxidative stress mechanisms as a possible link between a hostile gestational environment and adult disease. Therefore, in this study, we exposed pregnant Sprague-Dawley rats to nanosized titanium dioxide aerosols after implantation (gestational day 6). Pups were delivered, and the progeny grew into adulthood. Microvascular reactivity, mitochondrial respiration and hydrogen peroxide production of the coronary and uterine circulations of the female offspring were evaluated. While there were no significant differences within the maternal or litter characteristics, endothelium-dependent dilation and active mechanotransduction in both coronary and uterine arterioles were significantly impaired. In addition, there was a significant reduction in maximal mitochondrial respiration (state 3) in the left ventricle and uterus. These studies demonstrate microvascular dysfunction and coincide with mitochondrial inefficiencies in both the cardiac and uterine tissues, which may represent initial evidence that prenatal ENM exposure produces microvascular impairments that persist throughout multiple developmental stages.

Vascular distribution of nanomaterials

Once considered primarily occupational, novel nanotechnology innovations, and applications have led to widespread domestic use and intentional biomedical exposures. With these exciting advances, the breadth and depth of toxicological considerations must also be expanded. The vascular system interacts with every tissue in the body, striving to maintain homeostasis. Engineered nanomaterials (ENM) have been reported to distribute in many different tissues and organs. However, these observations have tended to use approaches requiring tissue homogenization and/or gross organ analyses. These techniques, while effective in establishing presence, preclude an exact determination of where ENM are deposited within a tissue. If nanotechnology is to achieve its full potential, it is necessary to identify this exact distribution and deposition of ENM throughout the cardiovascular system, with respect to vascular hemodynamics and in vivo ENM modifications taken into account. Distinct levels of the vasculature will first be described as individual compartments. Then the vasculature will be considered as a whole. These unique compartments and biophysical conditions will be discussed in terms of their propensity to favor ENM deposition. Understanding levels of the vasculature will also be discussed. Ultimately, future studies must verify the mechanisms speculated on and presented herein.

CONFLICT OF INTEREST

The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

Impact of outdoor air pollution on the incidence of tuberculosis in the Seoul metropolitan area, South Korea

BACKGROUND/AIMS

Although indoor air pollution is a well-known risk factor for tuberculosis (TB), the possible link between outdoor air pollution and TB development has not been examined fully. We assessed the impact of outdoor air pollution on TB development in the Seoul metropolitan area, South Korea.

METHODS

The mean concentrations of ambient particulate matter (PM) with an aerodynamic diameter ≤ 10 µm (PM10), O3, CO, NO2, and SO2 levels in Seoul, between January 1, 1997 and December 31, 2006, were determined. Furthermore, their association with the risk of developing TB after adjusting for socioeconomic status, between January 1, 2002 and December 31, 2006, was investigated.

RESULTS

Between January 1, 2002 and December 31, 2006, a total of 41,185 TB cases were reported in Seoul. Concentrations of PM10, O3, CO, and NO2 were not associated with TB incidence in males or females. However, the interquartile increase in SO2 concentration was associated with a 7% increment in TB incidence (relative risk [RR], 1.07; 95% credible interval [CrI], 1.03 to 1.12) in males but not in females (RR, 1.02; 95% CrI, 0.98 to 1.07).

CONCLUSIONS

Long-term exposure to ambient SO2 increased the risk of TB in males.

Vasodilation to PTH (1-84) in bone arteries is dependent upon the vascular endothelium and is mediated partially via VEGF signaling

BACKGROUND

Intermittent PTH administration directly stimulates osteoblasts; however, mechanisms of bone accrual that are independent of the direct actions on osteoblasts may be under-appreciated. Our aims were to decipher (1) whether PTH 1-84 augments vasodilation of the femoral principal nutrient artery (PNA), (2) whether 15 days of intermittent PTH 1-84 augments endothelium-dependent and/or -independent vasodilation of the femoral PNA, and (3) the signaling mechanisms involved.

METHODS

Experiment 1: Femoral PNAs from male Wistar rats were exposed to cumulative doses of PTH 1-84 with and without an anti-vascular endothelial growth factor antibody and/or the endothelial NO synthase inhibitor l-NAME. Experiment 2: Male Wistar rats were administered PTH and/or the anti-VEGF antibody for 2 weeks. Subsequently, endothelium-dependent vasodilation to acetylcholine and endothelium-independent vasodilation to sodium nitroprusside were assessed. In addition, endothelium-dependent signaling pathways were analyzed by use of l-NAME and/or and the cyclooxygenase inhibitor indomethacin.

RESULTS

Cumulative doses of PTH 1-84 induced vasodilation of the femoral PNA, which was reduced by 38% and 87% with the anti-VEGF antibody and l-NAME, respectively. Secondly, 2 weeks of intermittent PTH 1-84 administration doubled trabecular bone volume, augmented bone formation parameters and reduced osteoclast activity. In addition, PTH enhanced endothelium-dependent vasodilation via up-regulation of NO. Co-administration of the anti-VEGF antibody (1) inhibited the PTH-induced increase in bone volume and remodeling parameters and (2) blunted the augmented vasodilator responsiveness of the PNA. Finally, endothelium-dependent vasodilation in PTH-treated rats was highly correlated with trabecular bone volume.

CONCLUSION

As hypothesized, PTH enhanced endothelium-dependent vasodilation of the femoral PNA via augmented NO production and was mediated partially through VEGF signaling. Further, vasodilation to PTH appears independent of vascular smooth muscle cell participation. More importantly, the strong association between vasodilation and bone volume suggests that bone arteriolar function is critical for PTH-induced bone anabolism.

Aging and estrogen status: a possible endothelium-dependent vascular coupling mechanism in bone remodeling

Bone loss with aging and menopause may be linked to vascular endothelial dysfunction. The purpose of the study was to determine whether putative modifications in endothelium-dependent vasodilation of the principal nutrient artery (PNA) of the femur are associated with changes in trabecular bone volume (BV/TV) with altered estrogen status in young (6 mon) and old (24 mon) female Fischer-344 rats. Animals were divided into 6 groups: 1) young intact, 2) old intact, 3) young ovariectomized (OVX), 4) old OVX, 5) young OVX plus estrogen replacement (OVX+E2), and 6) old OVX+E2. PNA endothelium-dependent vasodilation was assessed in vitro using acetylcholine. Trabecular bone volume of the distal femoral metaphysis was determined by microCT. In young rats, vasodilation was diminished by OVX and restored with estrogen replacement (intact, 82±7; OVX, 61±9; OVX+E2, 90±4%), which corresponded with similar modifications in BV/TV (intact, 28.7±1.6; OVX, 16.3±0.9; OVX+E2, 25.7±1.4%). In old animals, vasodilation was unaffected by OVX but enhanced with estrogen replacement (intact, 55±8; OVX, 59±7; OVX+E2, 92±4%). Likewise, modifications in BV/TV followed the same pattern (intact, 33.1±1.6; OVX, 34.4±3.7; OVX+E2, 42.4±2.1%). Furthermore, in old animals with low endogenous estrogen (i.e., intact and old OVX), vasodilation was correlated with BV/TV (R² = 0.630; P<0.001). These data demonstrate parallel effects of estrogen on vascular endothelial function and BV/TV, and provide for a possible coupling mechanism linking endothelium-dependent vasodilation to bone remodeling.

Xenobiotic particle exposure and microvascular endpoints: a call to arms

Xenobiotic particles can be considered in two genres: air pollution particulate matter and engineered nanoparticles. Particle exposures can occur in the greater environment, the workplace, and our homes. The majority of research in this field has, justifiably, focused on pulmonary reactions and outcomes. More recent investigations indicate that cardiovascular effects are capable of correlating with established mortality and morbidity epidemiological data following particle exposures. While the preliminary and general cardiovascular toxicology has been defined, the mechanisms behind these effects, specifically within the microcirculation, are largely unexplored. Therefore, the purpose of this review is several fold: first, a historical background on toxicological aspects of particle research is presented. Second, essential definitions, terminology, and techniques that may be unfamiliar to the microvascular scientist will be discussed. Third, the most current concepts and hypotheses driving cardiovascular research in this field will be reviewed. Lastly, potential future directions for the microvascular scientist will be suggested. Collectively speaking, microvascular research in the particle exposure field represents far more than a "niche." The immediate demand for basic, translational, and clinical studies is high and diverse. Microvascular scientists at all career stages are strongly encouraged to expand their research interests to include investigations associated with particle exposures.

Comparing gravimetric and real-time sampling of PM(2.5) concentrations inside truck cabins

As part of a study on truck drivers' exposure and health risk, pickup and delivery (P&D) truck drivers' on-road exposure patterns to PM(2.5) were assessed in five, weeklong sampling trips in metropolitan areas of five U.S. cities from April to August of 2006. Drivers were sampled with real-time (DustTrak) and gravimetric samplers to measure average in-cabin PM(2.5) concentrations and to compare their correspondence in moving trucks. In addition, GPS measurements of truck locations, meteorological data, and driver behavioral data were collected throughout the day to determine which factors influence the relationship between real-time and gravimetric samplers. Results indicate that the association between average real-time and gravimetric PM(2.5) measurements on moving trucks was fairly consistent (Spearman rank correlation of 0.63), with DustTrak measurements exceeding gravimetric measurements by approximately a factor of 2. This ratio differed significantly only between the industrial Midwest cities and the other three sampled cities scattered in the South and West. There was also limited evidence of an effect of truck age. Filter samples collected concurrently with DustTrak measurements can be used to calibrate average mass concentration responses for the DustTrak, allowing for real-time measurements to be integrated into longer-term studies of inter-city and intra-urban exposure patterns for truck drivers.

Urban air pollution and emergency room admissions for respiratory symptoms: a case-crossover study in Palermo, Italy

BACKGROUND

Air pollution from vehicular traffic has been associated with respiratory diseases. In Palermo, the largest metropolitan area in Sicily, urban air pollution is mainly addressed to traffic-related pollution because of lack of industrial settlements, and the presence of a temperate climate that contribute to the limited use of domestic heating plants. This study aimed to investigate the association between traffic-related air pollution and emergency room admissions for acute respiratory symptoms.

METHODS

From January 2004 through December 2007, air pollutant concentrations and emergency room visits were collected for a case-crossover study conducted in Palermo, Sicily. Risk estimates of short-term exposures to particulate matter and gaseous ambient pollutants including carbon monoxide, nitrogen dioxide, and sulfur dioxide were calculated by using a conditional logistic regression analysis.

RESULTS

Emergency departments provided data on 48,519 visits for respiratory symptoms. Adjusted case-crossover analyses revealed stronger effects in the warm season for the most part of the pollutants considered, with a positive association for PM10 (odds ratio = 1.039, 95% confidence interval: 1.020 - 1.059), SO2 (OR = 1.068, 95% CI: 1.014 - 1.126), nitrogen dioxide (NO2: OR = 1.043, 95% CI: 1.021 - 1.065), and CO (OR = 1.128, 95% CI: 1.074 - 1.184), especially among females (according to an increase of 10 μg/m3 in PM10, NO2, SO2, and 1 mg/m3 in CO exposure). A positive association was observed either in warm or in cold season only for PM10.

CONCLUSIONS

Our findings suggest that, in our setting, exposure to ambient levels of air pollution is an important determinant of emergency room (ER) visits for acute respiratory symptoms, particularly during the warm season. ER admittance may be considered a good proxy to evaluate the adverse effects of air pollution on respiratory health.

A growing role for gender analysis in air pollution epidemiology

Epidemiologic studies of air pollution effects on respiratory health report significant modification by sex, although results are not uniform. Importantly, it remains unclear whether modifications are attributable to socially derived gendered exposures, to sex-linked physiological differences, or to some interplay thereof. Gender analysis, which aims to disaggregate social from biological differences between males and females, may help to elucidate these possible sources of effect modification. Studies of children suggest stronger effects among boys in early life and among girls in later childhood. The qualitative review describes possible sources of difference in air pollution response between women and men, which may vary by life stage, coexposures, hormonal status, or other factors. The sources of observed effect modifications remain unclear, although gender analytic approaches may help to disentangle gender and sex differences in pollution response. A framework for incorporating gender analysis into environmental epidemiology is offered, along with several potentially useful methods from gender analysis.

Role of quinones in the ascorbate reduction rates of S-nitrosoglutathione

Quinones are one of the largest classes of antitumor agents approved for clinical use, and several antitumor quinones are in various stages of clinical and preclinical development. Many of these are metabolites of, or are, environmental toxins. Because of their chemical structure they are known to enhance electron transfer processes such as ascorbate oxidation and NO reduction. The paraquinones 2,6-dimethyl-1,4-benzoquinone (DMBQ), 1,4-benzoquinone, methyl-1,4-benzoquinone, 2,6-dimethoxy-1,4-benzoquinone, 2-hydroxymethyl-6-methoxy-1,4-benzoquinone, trimethyl-1,4-benzoquinone, tetramethyl-1,4-benzoquinone, and 2,3-dimethoxy-5-methyl-1,4-benzoquinone; the paranaphthoquinones 1,4-naphthoquinone, menadione, 1,4-naphthoquinone-2-sulfonate, 2-ethylsulfanyl-3-methyl-1,4-naphthoquinone and juglone; and phenanthraquinone (PHQ) all enhance the anaerobic rate of ascorbate reduction of GSNO to produce NO and GSH. Rates of this reaction were much larger for p-benzoquinones and PHQ than for p-naphthoquinone derivatives with similar one-electron redox potentials. The quinone DMBQ also enhances the rate of NO production from S-nitrosylated bovine serum albumin upon ascorbate reduction. Density functional theory calculations suggest that stronger interactions between p-benzo- or phenanthrasemiquinones and GSNO than between p-naphthosemiquinones and GSNO are the major causes of these differences. Thus, quinones, and especially p-quinones and PHQ, could act as enhancers of NO release from GSNO in biomedical systems in the presence of ascorbate. Because quinones are exogenous toxins that could enter the human body via a chemotherapeutic application or as an environmental contaminant, they could boost the release of NO from S-nitrosothiol storages in the body in the presence of ascorbate and thus enhance the responses elicited by a sudden increase in NO levels.

A growing role for gender analysis in air pollution epidemiology

OBJECTIVE

Epidemiologic studies of air pollution effects on respiratory health report significant modification by sex, although results are not uniform. Importantly, it remains unclear whether modifications are attributable to socially derived gendered exposures, to sex-linked physiological differences, or to some interplay thereof. Gender analysis, which aims to disaggregate social from biological differences between males and females, may help to elucidate these possible sources of effect modification.

DATA SOURCES AND DATA EXTRACTION

A PubMed literature search was performed in July 2009, using the terms "respiratory" and any of "sex" or "gender" or "men and women" or "boys and girls" and either "PM2.5" (particulate matter <or= 2.5 microm in aerodynamic diameter) or "NO2" (nitrogen dioxide). I reviewed the identified studies, and others cited therein, to summarize current evidence of effect modification, with attention to authors' interpretation of observed differences. Owing to broad differences in exposure mixes, outcomes, and analytic techniques, with few studies examining any given combination thereof, meta-analysis was not deemed appropriate at this time.

DATA SYNTHESIS

More studies of adults report stronger effects among women, particularly for older persons or where using residential exposure assessment. Studies of children suggest stronger effects among boys in early life and among girls in later childhood.

CONCLUSIONS

The qualitative review describes possible sources of difference in air pollution response between women and men, which may vary by life stage, coexposures, hormonal status, or other factors. The sources of observed effect modifications remain unclear, although gender analytic approaches may help to disentangle gender and sex differences in pollution response. A framework for incorporating gender analysis into environmental epidemiology is offered, along with several potentially useful methods from gender analysis.

Estrogen replacement restores flow-induced vasodilation in coronary arterioles of aged and ovariectomized rats

The risk for cardiovascular disease (CVD) increases with advancing age; however, the age at which CVD risk increases significantly is delayed by more than a decade in women compared with men. This cardioprotection, which women experience until menopause, is presumably due to the presence of ovarian hormones, in particular, estrogen. The purpose of this study was to determine how age and ovarian hormones affect flow-induced vasodilation in the coronary resistance vasculature. Coronary arterioles were isolated from young (6 mo), middle-aged (14 mo), and old (24 mo) intact, ovariectomized (OVX), and ovariectomized + estrogen replaced (OVE) female Fischer-344 rats to assess flow-induced vasodilation. Advancing age impaired flow-induced dilation of coronary arterioles (young: 50 +/- 4 vs. old: 34 +/- 6; % relaxation). Ovariectomy reduced flow-induced dilation in arterioles from young females, and estrogen replacement restored vasodilation to flow. In aged females, flow-induced vasodilation of arterioles was unaltered by OVX; however, estrogen replacement improved flow-induced dilation by approximately 160%. The contribution of nitric oxide (NO) to flow-induced dilation, assessed by nitric oxide synthase (NOS) inhibition with N(G)-nitro-l-arginine methyl ester (l-NAME), declined with age. l-NAME did not alter flow-induced vasodilation in arterioles from OVX rats, regardless of age. In contrast, l-NAME reduced flow-induced vasodilation of arterioles from estrogen-replaced rats at all ages. These findings indicate that the age-induced decline of flow-induced, NO-mediated dilation in coronary arterioles of female rats is related, in part, to a loss of ovarian estrogen, and estrogen supplementation can improve flow-induced dilation, even at an advanced age.