Ana Julia de Faria Coimbra Lichtenfels

Chronic Exposure to Ambient Levels of Urban Particles Affects Mouse Lung Development

RATIONALE Chronic exposure to air pollution has been associated with adverse effects on childrens lung growth. OBJECTIVES We analyzed the effects of chronic exposure to urban levels of particulate matter (PM) on selected phases of mouse lung development. METHODS The exposure occurred in two open-top chambers (filtered and nonfiltered) placed 20 m from a street with heavy traffic in São Paulo, 24 hours/day for 8 months. There was a significant reduction of the levels of PM(2.5) inside the filtered chamber (filtered = 2.9 +/- 3.0 microg/m(3), nonfiltered = 16.8 +/- 8.3 microg/m(3); P = 0.001). At this exposure site, vehicular sources are the major components of PM(2.5) (PM <or= 2.5 microm). Exposure of the parental generation in the two chambers occurred from the 10th to the 120th days of life. After mating and birth of offspring, a crossover of mothers and pups occurred within the chambers, resulting in four groups of pups: nonexposed, prenatal, postnatal, and pre+postnatal. Offspring were killed at the age of 15 (n = 42) and 90 (n = 35) days; lungs were analyzed by morphometry for surface to volume ratio (as an estimator of alveolization). Pressure-volume curves were performed in the older groups, using a 20-ml plethysmograph. MEASUREMENTS AND MAIN RESULTS Mice exposed to PM(2.5) pre+postnatally presented a smaller surface to volume ratio when compared with nonexposed animals (P = 0.036). The pre+postnatal group presented reduced inspiratory and expiratory volumes at higher levels of transpulmonary pressure (P = 0.001). There were no differences among prenatal and postnatal exposure and nonexposed animals. CONCLUSIONS Our data provide anatomical and functional support to the concept that chronic exposure to urban PM affects lung growth.

Exploring the clastogenic effects of air pollutants in São Paulo (Brazil) using the Tradescantia micronuclei assay

This study was designed to determine the clastogenicity of particulate matter (aerodynamic diameter smaller than 10 microm) in the urban polluted air in the city of São Paulo. The Tradescantia-micronucleus (Trad-MCN) assay was used throughout this study to evaluate the clastogenicity of the extracts of the particulate matter. Tradescantia pallida (Rose) Hunt. cv. purpurea, an indigenous cultivar, was used in the Trad-MCN assay. The efficacy of this plant material for the Trad-MCN assay was validated with dose-response studies using formaldehyde and beta radiation. Dose-response curves were established with these known mutagens. The extracts of the PM10 particles at concentrations between 5 and 50 ppm induced a dose-related increase in MCN frequencies. The results indicate that T. pallida is equally sensitive to mutagens as the standard Tradescantia clone 4430 or 03 and the particulate matter in the urban air are clastogenic to the chromosomes of this plant. Inhalation of these particles by urban dwellers may affect their health by inducing similar genetic damage.

Effects of ambient levels of air pollution generated by traffic on birth and placental weights in mice

OBJECTIVE To examine whether there is an association between fetal and/or placental weight and exposure to ambient levels of air pollution in mice. DESIGN Chronic experiments on mice that were exposed to polluted vs. clean air. SETTING Environmental exposure to atmospheric pollution. ANIMAL(S) Female Swiss mice (n = 70) were maintained at different stages of gestation in an exposure chamber located at an intersection with heavy traffic in a major city in Brazil. Control mice were maintained in a similar chamber, located adjacent to the exposure chamber but equipped with filters for particles and reactive gases. INTERVENTION(S) Animals were divided into six groups as follows: no exposure, exposure to a polluted chamber throughout gestation, exposure to a polluted chamber during the 1st week of pregnancy, exposure to a polluted chamber during the 2nd and 3rd weeks, exposure to a polluted chamber during the 1st and 2nd week, and exposure to a polluted chamber during the 3rd week. MAIN OUTCOME MEASURE(S) At the end of the gestational period, the determination of fetal and placental weight was performed after cesarean section. RESULT(S) Exposure to air pollution during the 1st week of pregnancy promoted a significant reduction in fetal weight. Mice exposed to polluted air, in any phase of gestation, presented with lower placental weight in comparison to mice maintained in clean chambers. CONCLUSION(S) Exposure to ambient levels of traffic pollution at early phases of gestation is a determinant for decreased final fetal weight. Placental weight is reduced with exposure to air pollution at any phase of gestation.

Exposure to ambient levels of particles emitted by traffic worsens emphysema in mice

OBJECTIVES We investigated effects of chronic exposure (2 months) to ambient levels of particulate matter (PM) on development of protease-induced emphysema and pulmonary remodeling in mice. METHODS Balb/c mice received nasal drop of either papain or normal saline and were kept in two exposure chambers situated in an area with high traffic density. One of them received ambient air and the other had filters for PM. RESULTS mean concentration of PM10 was 2.68 +/- 0.38 and 33.86 +/- 2.09 microg/m3, respectively, in the filtered and ambient air chambers (p < 0.001). After 2 months of exposure, lungs from papain-treated mice kept in the chamber with ambient air presented greater values of mean linear intercept, an increase in density of collagen fibers in alveolar septa and in expression of 8-isoprostane (p = 0.002, p < 0.05 and p = 0.002, respectively, compared to papain-treated mice kept in the chamber with filtered air). We did not observe significant differences between these two groups in density of macrophages and in amount of cells expressing matrix metalloproteinase-12. There were no significant differences in saline-treated mice kept in the two chambers. CONCLUSIONS We conclude that exposure to urban levels of PM worsens protease-induced emphysema and increases pulmonary remodeling. We suggest that an increase in oxidative stress induced by PM exposure influences this response. These pulmonary effects of PM were observed only in mice with emphysema.

Biological effects and dose-response assessment of diesel exhaust particles on in vitro early embryo development in mice

An increased risk of early pregnancy loss in women briefly exposed to high levels of ambient particulate matter during the preconceptional period was recently observed. The effects of this exposure on early embryo development are unknown. This study was designed to assess the dose-response and biological effects of diesel exhaust particles (DEP) on in vitro embryo development using the in vitro fertilization (IVF) mouse model. Zygotes obtained from superovulated mice after IVF were randomly cultured in different DEP concentrations (0, 0.2, 2, and 20 microg/cm(2)) for 5 days and observed for their capacity to attach and develop on a fibronectin matrix until day 8. Main outcome measures included blastocyst rates 96 and 120 h after insemination, hatching discriminatory score, total cell count, proportion of cell allocation to inner cell mass (ICM) and trophectoderm (TE), ICM morphology, attachment rate and outgrowth area, apoptosis and necrosis rates, and Oct-4 and Cdx-2 expression. Multivariate analysis showed a negative dose-dependent effect on early embryo development and hatching process, blastocyst cell allocation, and ICM morphology. Although blastocyst attachment and outgrowth were not affected by DEP, a significant impairment of ICM integrity was observed in day 8 blastocysts. Cell death through apoptosis was significantly higher after DEP exposure. Oct-4 expression and the Oct-4/Cdx-2 ratio were significantly decreased in day 5 blastocysts irrespective of DEP concentration. Results suggest that DEP appear to play an important role in disrupting cell lineage segregation and ICM morphological integrity even at lower concentrations, compromising future growth and viability of the blastocyst.

Vascular remodeling process in reversibility of pulmonary arterial hypertension secondary to congenital heart disease.

Pulmonary vascular remodeling process was analyzed using morphometry in lung biopsy specimens taken from 26 children, aged 6 to 160 months, who had congenital heart disease and significant pulmonary arterial hypertension. Reparative surgery was performed in 22 patients and palliative surgery was performed in four patients. One patient expired postoperatively and four others after hospital discharge. Vascular remodeling examination revealed a characteristic pathological picture: pronounced medial thickening with increased collagen content (fibrosis), without significant arterial intimal proliferation. At a mean follow-up of 44 months, 72% of the survivors were asymptomatic with no medication. Diagnosed by echocardiogram, 22% of these patients were shown to have pulmonary arterial hypertension. The characteristic pathological features described above occurred in 38% of the patients who either expired or had pulmonary hypertension postoperatively. These findings were an aid to identifying a high risk group in which the outcome does not meet expectations for the classical grade I and II changes. We concluded that the presence of isolated medial thickening does not ensure either survival or a normal postoperative pulmonary arterial pressure at late follow-up and that the collagen content can be a better reference for good outcome. Early intracardiac repair is recommended before the development of significant medial fibrosis.

Tradescantia pallida cv. purpurea Boom in the Characterization of Air Pollution by Accumulation of Trace Elements

Abstract Tradescantia pallida cv. purpurea, a plant species widely employed for ornamentation in Brazil, has been successfully used for monitoring the genotoxicity of various agents by the micronucleus assay. To amplify knowledge about its suitability as a bioindicator species, its capacity for accumulating trace elements from urban air pollution was evaluated. T. pallida was rooted using standardized soil, and the vases were distributed in two highly polluted sites of the urban area of São Paulo, Brazil (Cerqueira César and Congonhas districts), and in one unpolluted control site situated approximately 50 km from downtown São Paulo (in Caucaia do Alto). Approximately six months after exposure to pollutants, adult leaves of this plant were collected monthly for 12 months. The leaves were washed with deionized water, dried, and ground for analyses. Characterization of element levels was carried out by neutron activation analysis. Powdered samples and standards were irradiated at the IEA-R1 nuclear reactor for short and long periods, and concentrations of As, Ba, Br, Ca, Ce, Cl, Cr, Co, Fe, K, La, Mn, Na, Rb, Sb, Sc, Sr, Th, and Zn were determined. Analysis of variance applied to the results indicated that samples from polluted sites present the highest concentrations of Ba, Ce, Cr, Co, Fe, La, Sb, and Sc (p < 0.05). Discriminant analysis revealed that it was possible to distinguish the two polluted areas with a precision of 97.5%, based on the amount of pollutant elements measured in the plants at each site. The results indicated the potential use of T. pallida as an accumulator plant for air pollution biomonitoring.

Effects of Chronic Exposure to Air Pollution from Sao Paulo City on Coronary of Swiss Mice, from Birth to Adulthood

To explore the hypothesis that air pollution promotes cardiovascular changes, Swiss mice were continuously exposed, since birth, in two open-top chambers (filtered and nonfiltered for airborne particles ≤ 0.3 μm) placed 20 m from a street with heavy traffic in downtown Sao Paulo, twenty-four hours per day for four months. Fine particle (PM2.5) concentration was determined gravimetrically; hearts were analyzed by morphometry. There was a reduction of the PM2.5 inside the filtered chamber (filtered = 8.61±0.79 μg/m3, nonfiltered = 18.05±1.25 μg/m3, p < .001). Coronary arteries showed no evidence of luminal narrowing in the exposed group but presented higher collagen content in the adventitia of LV large-sized and RV midsized vessels (p = .001) and elastic fibers in both tunicae adventitia and intima-media of almost all sized arterioles from both ventricles (p = .03 and p = .001, respectively). We concluded that chronic exposure to urban air since birth induces mild but significant vascular structural alterations in normal individuals, presented as coronary arteriolar fibrosis and elastosis. These results might contribute to altered vascular response and ischemic events in the adulthood.

Intrauterine exposure to diesel exhaust diminishes adult ovarian reserve

OBJECTIVE To analyze ovarian and uterine morphologic changes resulting from intrauterine and postnatal exposure to diesel exhaust. DESIGN Crossover study. Experimental groups: intrauterine and postnatal clean air exposure; intrauterine exposure to diesel only; postnatal exposure to diesel only; and intrauterine and postnatal exposure to diesel. SETTING Laboratory of Experimental Air Pollution. ANIMAL(S) Swiss mice. INTERVENTION(S) Mice exposed to diesel exhaust with doses that correspond to the daily average PM₂.₅ levels (fine particles in the ambient air 2.5 μm or less in size) reported by the World Health Organization. MAIN OUTCOME MEASURE(S) Morphometric analyses of the ovaries and uterus were performed to define the relative area occupied by follicles, corpus luteum, and stroma and the proportionate area of glands, epithelial layer, and stroma within the uterine endometrium. RESULT(S) A significant reduction in the proportion of primordial follicles was observed in intrauterine-exposed animals, those exposed during the postnatal period, and in animals exposed during both phases. Primary follicle proportion was reduced in animals exposed during pregnancy. No significant changes were detected in uterine morphology. CONCLUSION(S) Intrauterine exposure to acceptable levels of diesel exhaust compromises the reproductive potential of female mice, diminishing ovarian reserve when sexual maturity is achieved. This effect could increase the risk of premature menopause. The findings raise concern about current environmental guidelines for diesel exposure, warranting more careful examination of this issue in humans by regulatory authorities.

Acute exposure to diesel and sewage biodiesel exhaust causes pulmonary and systemic inflammation in mice

Biodiesel is a renewable energy source that reduces particle emission, but few studies have assessed its effects. To assess the effects of acute inhalation of two doses (600 and 1200 μg/m3) of diesel (DE) and biodiesel (BD) fuels on the inflammatory pulmonary and systemic profile of mice. Animals were exposed for 2 h in an inhalation chamber inside the Container Laboratory for Fuels. Heart rate, heart rate variability (HRV) and blood pressure were determined 30 min after exposure. After 24 h, we analyzed the lung inflammation using bronchoalveolar lavage fluid (BALF); neutrophil and macrophage quantification in the lung parenchyma was performed, and blood and bone marrow biomarkers as well as receptor of endothelin-A (ET-Ar), receptor of endothelin-B (ET-Br), vascular cell adhesion molecule 1 (VCAM-1), inducible nitric oxide synthase (iNOs) and isoprostane (ISO) levels in the pulmonary vessels and bronchial epithelium were evaluated. HRV increased for BD600, D600 and D1200 compared to filtered air (FA). Both fuels (DE and BD) produced alterations in red blood cells independent of the dose. BALF from the BD600 and BD1200 groups showed an increase in neutrophils compared to those of the FA group. Numeric density of the polymorphonuclear and mononuclear cells was elevated with BD600 compared to FA. In the peribronchiolar vessels, there was an increase in ET-Ar and ET-Br expression following BD600 compared to FA; and there was a reduction in the iNOs expression for BD1200 and the VCAM-1 for D1200 compared to FA. In the bronchial epithelium, there was an increase in ETAr at BD600, ET-Br at two doses (600 and 1200 μg/m3) of DE and BD, iNOs at D600 and VCAM-1 at BD1200 and D600; all groups were compared to the FA group. Acute exposure to DE and BD derived from sewage methyl esters triggered pulmonary and cardiovascular inflammatory alterations in mice.