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 children`s 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 Sao 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 mu g/m(3), nonfiltered = 16.8 +/- 8.3 mu g/m(3); P = 0.001). At this exposure site, vehicular sources are the major components of PM(2.5) (PM <= 2.5 mu m). 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.

Mathematical modeling of pressurized system behaviour with entrapped air

The presence of entrapped air in pressurized hydraulic systems is considered a critical condition for the infrastructure security, due to the transient pressure enhancement related with its dynamic behaviour, similar to non-linear spring action. A mathematical model for the assessment of hydraulic transients resulting from rapid pressurizations, under referred condition is presented. Water movement was modeled through the elastic column theory considering a moving liquid boundary and the entrapped air pocket as lumped gas mass, where the acoustic effects are negligible. The method of characteristics was used to obtain the numerical solution of the liquid flow. The resulting model is applied to an experimental set-up having entrapped air in the top of a vertical pipe section and the numerical results are analyzed.

Experimental assessment of pressure drop in air stripping columns

One important step in the design of air stripping operations for the removal of VOC is the choice of operating conditions, which are based in the phase ratio. This parameter sets on directly the stripping factor and the efficiency of the operation. Its value has an upper limit determined by the flooding regime, which is previewed using empirical correlations, namely the one developed by Eckert. This type of approach is not suitable for the development of algorithms. Using a pilot scale column and a convenient solution, the pressure drop was determined in different operating conditions and the experimental values were compared with the estimations. This particular research will be incorporated in a global model for simulating the dynamics of air stripping using a multi variable distributed parameter system.

Practical software improve design and performance of a randomly packed air stripping column for removing volatile organic compounds from water

STRIPPING is a software application developed for the automatic design of a randomly packing column where the transfer of volatile organic compounds (VOCs) from water to air can be performed and to simulate it’s behaviour in a steady-state. This software completely purges any need of experimental work for the selection of diameter of the column, and allows a choice, a priori, of the most convenient hydraulic regime for this type of operation. It also allows the operator to choose the model used for the calculation of some parameters, namely between the Eckert/Robbins model and the Billet model for estimating the pressure drop of the gaseous phase, and between the Billet and Onda/Djebbar’s models for the mass transfer. Illustrations of the graphical interface offered are presented.

Towards cryogenic liquid –vapor energy storage units for space applications

Dissertation to obtain the Doctoral degree in Physics Engineering

Cross-scale determinants of palm species distribution

We investigate palm species distribution, richness and abundance along the Mokoti, a seasonally-dry river of southeastern Amazon and compare it to the patterns observed at a large scale, comprising the entire Brazilian territory. A total of 694 palms belonging to 10 species were sampled at the Mokoti River basin. Although the species showed diverse distribution patterns, we found that local palm abundance, richness and tree basal area were significantly higher from the hills to the bottomlands of the study region, revealing a positive association of these measures with moisture. The analyses at the larger spatial scale also showed a strong influence of vapor pressure (a measure of moisture content of the air, in turn modulated by temperature) and seasonality in temperature: the richest regions were those where temperature and humidity were simultaneously high, and which also presented a lower degree of seasonality in temperature. These results indicate that the distribution of palms seems to be strongly associated with climatic variables, supporting the idea that, by 'putting all the eggs in one basket' (a consequence of survival depending on the preservation of a single irreplaceable bud), palms have become vulnerable to extreme environmental conditions. Hence, their distribution is concentrated in those tropical and sub-tropical regions with constant conditions of (mild to high) temperature and moisture all year round.

Vapor - liquid equilibrium of systems containing perfluoromethyl-cyclohexane and hydrocarbons

Vapor - liquid equilibrium data for the binary systems: Perfluoromethylcyclohexane + n-Hexane and Perfluoromethylcyclohexane + 1-Hexene were determined at 93.3 KPa and 328.15 K. The vapor pressure for the pure components were also measured to calculate the Antoine constants. The data were correlated by using the Van-Laar, Margules, Wilson, NRTL and UNIQUAC equations. UNIFAC group-contribution parameters between CH, and CF,, and CH,=CH and CF, were also calculated.

Pulmonary artery pressure and cardiac function in children and adolescents after rapid ascent to 3,450 m.

High-altitude destinations are visited by increasing numbers of children and adolescents. High-altitude hypoxia triggers pulmonary hypertension that in turn may have adverse effects on cardiac function and may induce life-threatening high-altitude pulmonary edema (HAPE), but there are limited data in this young population. We, therefore, assessed in 118 nonacclimatized healthy children and adolescents (mean ± SD; age: 11 ± 2 yr) the effects of rapid ascent to high altitude on pulmonary artery pressure and right and left ventricular function by echocardiography. Pulmonary artery pressure was estimated by measuring the systolic right ventricular to right atrial pressure gradient. The echocardiography was performed at low altitude and 40 h after rapid ascent to 3,450 m. Pulmonary artery pressure was more than twofold higher at high than at low altitude (35 ± 11 vs. 16 ± 3 mmHg; P < 0.0001), and there existed a wide variability of pulmonary artery pressure at high altitude with an estimated upper 95% limit of 52 mmHg. Moreover, pulmonary artery pressure and its altitude-induced increase were inversely related to age, resulting in an almost twofold larger increase in the 6- to 9- than in the 14- to 16-yr-old participants (24 ± 12 vs. 13 ± 8 mmHg; P = 0.004). Even in children with the most severe altitude-induced pulmonary hypertension, right ventricular systolic function did not decrease, but increased, and none of the children developed HAPE. HAPE appears to be a rare event in this young population after rapid ascent to this altitude at which major tourist destinations are located.

Residential Exposure to Outdoor Air Pollution during Pregnancy and Anthropometric Measures at Birth in a Multicenter Cohort in Spain

BACKGROUND. A growing body of research suggests that prenatal exposure to air pollution may be harmful to fetal development. We assessed the association between exposure to air pollution during pregnancy and anthropometric measures at birth in four areas within the Spanish Children's Health and Environment (INMA) mother and child cohort study. METHODS. Exposure to ambient nitrogen dioxide (NO2) and benzene was estimated for the residence of each woman (n = 2,337) for each trimester and for the entire pregnancy. Outcomes included birth weight, length, and head circumference. The association between residential outdoor air pollution exposure and birth outcomes was assessed with linear regression models controlled for potential confounders. We also performed sensitivity analyses for the subset of women who spent more time at home during pregnancy. Finally, we performed a combined analysis with meta-analysis techniques. RESULTS. In the combined analysis, an increase of 10 µg/m3 in NO2 exposure during pregnancy was associated with a decrease in birth length of -0.9 mm [95% confidence interval (CI), -1.8 to -0.1 mm]. For the subset of women who spent ≥ 15 hr/day at home, the association was stronger (-0.16 mm; 95% CI, -0.27 to -0.04). For this same subset of women, a reduction of 22 g in birth weight was associated with each 10-µg/m3 increase in NO2 exposure in the second trimester (95% CI, -45.3 to 1.9). We observed no significant relationship between benzene levels and birth outcomes. CONCLUSIONS. NO2 exposure was associated with reductions in both length and weight at birth. This association was clearer for the subset of women who spent more time at home.

Health effects of occupational exposure to traffic particles and noise

Exposure to fine particles and noise has been linked to cardiovascular diseases and elevated cardiovascular mortality affecting the worldwide population. Residence and/or work in proximity to emission sources as for example road traffic leads to an elevated exposure and a higher risk for adverse health effects. Highway maintenance workers spend most of their work time in traffic and are exposed regularly to particles and noise. The aims of this thesis were to provide a better understanding of the workers' mixed exposure to particles and noise and to assess cardiopulmonary short term health effects in relation to this exposure. Exposure and health data were collected in collaboration with 8 maintenance centers of the Swiss Road Maintenance Services located in the cantons Bern, Fribourg and Vaud in western Switzerland. Repeated measurements with 18 subjects were conducted during 50 non-consecutive work shifts between Mai 2010 and February 2012, equally distributed over all seasons. In the first part of this thesis we tested and validated measurements of ultrafine particles with a miniature diffusion size classifier (miniDiSC) - a novel particle counting device that was used for the exposure assessment during highway maintenance work. We found that particle numbers and average particle size measured by the miniDiSC were highly correlated with data from the P-TRAK, a condensation particle counter (CPC), as well as from a scanning mobility particle sizer (SMPS). However, the miniDiSC measured significantly more particles than the P-TRAK and significantly less than the SMPS in its full size range. Our data suggests that the instrument specific cutoffs were the main reason for the different particle counts. The first main objective of this thesis was to investigate the exposure of highway maintenance workers to air pollutants and noise, in relation to the different maintenance activities. We have seen that the workers are regularly exposed to high particle and noise levels. This was a consequence of close proximity to highway traffic and the use of motorized working equipment such as brush cutters, chain saws, generators and pneumatic hammers during which the highest exposure levels occurred. Although exposure to air pollutants were not critical if compared to occupational exposure limits, the elevated exposure to particles and noise may lead to a higher risk for cardiovascular diseases in this worker population. The second main objective was to investigate cardiopulmonary short-term health effects in relation to the particle and noise exposure during highway maintenance work. We observed a PM2.5 related increase of the acute-phase inflammation markers C-reactive protein and serum amyloid A and a decrease of TNFa. Heart rate variability increased as a consequence of particle as well as noise exposure. Increased high frequency power indicated a stronger parasympathetic influence on the heart. Elevated noise levels during recreational time, after work, were related to increased blood pressure. Our data confirmed that highway maintenance workers are exposed to elevated levels of particles and noise as compared to the average population. This exposure poses a cardiovascular health risk and it is therefore important to make efforts to better protect the workers health. The use of cleaner machines during maintenance work would be a major step to improve the workers' situation. Furthermore, regulatory policies with the aim of reducing combustion and non-combustion emissions from road traffic are important for the protection of workers in traffic environments and the entire population.

Enhanced diastolic reflections on arterial pressure pulse during exercise recovery

RESUMEDurant la phase de récupération d'un exercice de course à pied d'intensité maximale ou submaximale, une augmentation de la pression artérielle systolique centrale (aortique) résultant de la réflexion des ondes de pouls sur l'arbre vasculaire est constatée chez l'individu en bonne santé. En diastole cependant, l'impact de la réflexion de ces ondes de pouls sur la pression centrale demeure inconnu durant la récupération d'un exercice.Nous avons évalué les ondes de pouls centrales systolique et diastolique chez onze athlètes d'endurance durant la phase de récupération d'un exercice de course à pied dans des conditions d'effort maximal (sur tapis de course) et lors d'un effort submaximal lors d'une course à pied de 4000 mètres en plein air sur terrain mixte.Pour chaque sujet et lors des deux exercices, l'onde de pouls a été mesurée au niveau radial par tonométrie d'aplanation durant une phase de repos précédant l'exercice, puis à 5, 15, 25, 35 et 45 minutes après la fin de l'exercice. En utilisant une fonction mathématique de transfert, l'onde de pouls centrale a été extrapolée à partir de l'onde de pouls radiale. En compilant la forme de l'onde de pouls centrale avec une mesure simultanée de la pression artérielle brachiale, un index d'augmentation de l'onde de pouls en systole (Alx) et en diastole (Als) peut être calculé, reflétant l'augmentation des pressions résultant de la réflexion des ondes sur l'arbre vasculaire périphérique.A 5 minutes de la fin de l'exercice, les deux index ont été mesurés moindres que ceux mesurés lors de la phase précédant celui-ci. Lors des mesures suivantes, Alx est resté bas, alors que Aid a progressivement augmenté pour finalement dépasser la valeur de repos après 45 minutes de récupération. Le même phénomène a été constaté pour les deux modalités d'exercice (maximal ou submaximal). Ainsi, au-delà de quelques minutes de récupération après un exercice de course d'intensité maximale ou submaximale, nous avons montré par ces investigations que les ondes de pouls réfléchies en périphérie augmentent de façon sélective la pression centrale en diastole chez l'athlète d'endurance.ABSTRACTDuring recovery from a maximal or submaximal aerobic exercise, augmentation of central (aortic) systolic pressure by reflected pressure waves is blunted in healthy humans. However, the extent to which reflected pressure waves modify the central pulse in diastole in these conditions remains unknown. We evaluated systolic and diastolic central reflected waves in 11 endurance-trained athletes on recovery from a maximal running test on a treadmill (treadmill-max) and a 4000m run in field conditions. On both occasions in each subject, the radial pulse was recorded with applanation tonometry in the resting preexercise state and then 5, 15, 25, 35, and 45 minutes after exercise termination. From the central waveform, as reconstructed by application of a generalized transfer function, we computed a systolic (Alx) and a diastolic index (Aid) of pressure augmentation by reflections. At 5 minutes, both indices were below preexercise. At further time-points, Alx remained low, while Aid progressively increased, to overshoot above preexercise at 45 minutes. The same behavior was observed with both exercise types. Beyond the first few minutes of recovery following either maximal or submaximal aerobic exercise, reflected waves selectively augment the central pressure pulse in diastole, at least in endurance- trained athletes.

Prenatal exposure to traffic-related air pollution and ultrasound measures of fetal growth in the INMA Sabadell cohort

Background: Few studies have used longitudinal ultrasound measurements to assess the effect of traffic-related air pollution on fetal growth.Objective: We examined the relationship between exposure to nitrogen dioxide (NO2) and aromatic hydrocarbons [benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX)] on fetal growth assessed by 1,692 ultrasound measurements among 562 pregnant women from the Sabadell cohort of the Spanish INMA (Environment and Childhood) study.Methods: We used temporally adjusted land-use regression models to estimate exposures to NO2 and BTEX. We fitted mixed-effects models to estimate longitudinal growth curves for femur length (FL), head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and estimated fetal weight (EFW). Unconditional and conditional SD scores were calculated at 12, 20, and 32 weeks of gestation. Sensitivity analyses were performed considering time–activity patterns during pregnancy.Results: Exposure to BTEX from early pregnancy was negatively associated with growth in BPD during weeks 20–32. None of the other fetal growth parameters were associated with exposure to air pollution during pregnancy. When considering only women who spent 2 hr/day in nonresidential outdoor locations, effect estimates were stronger and statistically significant for the association between NO2 and growth in HC during weeks 12–20 and growth in AC, BPD, and EFW during weeks 20–32.Conclusions: Our results lend some support to an effect of exposure to traffic-related air pollutants from early pregnancy on fetal growth during mid-pregnancy.

Contribution of the gap junction proteins Connexin40 and Connexin43 to the control of blood pressure

Summary Cells in tissues and organs coordinate their activities by communicating with each other through intercellular channels named gap junctions. These channels are conduits between the cytoplasmic compartments of adjacent cells, allowing the exchange of small molecules which may be crucial for hormone secretion. Renin is normally secreted in a regulated manner by specific cells of the juxtaglomerular apparatus located within the renal cortex. Gap junctional communication may be requisite to maintain an accurate functioning in coordination of renin-producing cells, more especially as renin is of paramount importance for the control of blood pressure. Connexin43 (Cx43) and Cx40 form gap junctions that link in vivo the cells of the juxtaglomerular apparatus. Cx43 links the endothelial cells, whereas gap junctions made of Cx40 connect the endothelial cells, the renin secreting cells, as well as the endothelial cells of to the renin-secreting cells of the afferent arteriole. The observation that loss of Cx40 results in chronic hypertension associated with altered vasomotion and signal conduction along arterioles, has lead us to suggest that connexins may contribute to control blood pressure by participating to the integration of various mechanical, osmotic and electrochemical stimuli involved in the control of renin secretion and by mediating the adaptive changes of the vascular wall induced by elevated blood pressure and mechanical stress. We therefore postulated that the absence of Cx40 could have deleterious effects on the coordinated functioning of the renin-containing cells, hence accounting for hypertension. In the first part of my thesis, we reported that Cx40-deficient mice (Cx40) are hypertensive due to increased plasma renin levels and numbers of renin-producing cells. Besides, we demonstrated that prostaglandins and nitric oxide, which are possible mediators in the regulation of renin secretion by the macula densa, exert a critical role in the mechanisms controlling blood pressure ín Cx40 knockout hypertensive mice. In view of previous studies that stated avessel-specifc increase in the expression of Cx43 during renin-dependent hypertension, we hypothesized that Cx43 channels are particularly well-matched to integrate the response of cells constituting the vascular wall to hypertensive conditions. Using transgenic mice in which Cx43 was replaced by Cx32, we revealed that the replacement of Cx43 by Cx32 is associated with decreased expression and secretion of renin and prevent the renin-dependent hypertension which is normally induced in the 2K1C model. To gain insights into the regulation of connexins in two separate tissues exposed to the same fluid pressure, the second part of my thesis work was dedicated to the study of the impact of chronic hypertension and related hypertrophy on the expression of the cardiovascular connexins (Cx40, Cx37, Cx43 and Cx45) in mouse aorta and heart. Our results documented that the expression of connexins is differentially regulated in mouse aorta. according to the models of hypertension. Thus, blood pressure induces mechanical forces that differentially alter the expression of vascular connexins in order to respond to an adaptation of the aortic wall observed under pathological conditions. Altogether these data provide the first evidences that intercellular communication mediated by gap junctions is required for a proper renin secretion from the juxtaglomerular apparatus in order to control blood pressure.

Respiratory nitric oxide and pulmonary artery pressure in children of aymara and European ancestry at high altitude.

Invasive studies suggest that healthy children living at high altitude display pulmonary hypertension, but the data to support this assumption are sparse. Nitric oxide (NO) synthesized by the respiratory epithelium regulates pulmonary artery pressure, and its synthesis was reported to be increased in Aymara high-altitude dwellers. We hypothesized that pulmonary artery pressure will be lower in Aymara children than in children of European ancestry at high altitude, and that this will be related to increased respiratory NO. We therefore compared pulmonary artery pressure and exhaled NO (a marker of respiratory epithelial NO synthesis) between large groups of healthy children of Aymara (n = 200; mean +/- SD age, 9.5 +/- 3.6 years) and European ancestry (n = 77) living at high altitude (3,600 to 4,000 m). We also studied a group of European children (n = 29) living at low altitude. The systolic right ventricular to right atrial pressure gradient in the Aymara children was normal, even though significantly higher than the gradient measured in European children at low altitude (22.5 +/- 6.1 mm Hg vs 17.7 +/- 3.1 mm Hg, p < 0.001). In children of European ancestry studied at high altitude, the pressure gradient was 33% higher than in the Aymara children (30.0 +/- 5.3 mm Hg vs 22.5 +/- 6.1 mm Hg, p < 0.0001). In contrast to what was expected, exhaled NO tended to be lower in Aymara children than in European children living at the same altitude (12.4 +/- 8.8 parts per billion [ppb] vs 16.1 +/- 11.1 ppb, p = 0.06) and was not related to pulmonary artery pressure in either group. Aymara children are protected from hypoxic pulmonary hypertension at high altitude. This protection does not appear to be related to increased respiratory NO synthesis.

Mesure de la pression artérielle: meilleur moyen d'évaluer le risque cardiovasculaire [Measurement of blood pressure: best way to assess cardiovascular risk?]

Measurement of the blood pressure by the physician remains an essential step in the evaluation of cardiovascular risk. Ambulatory measurement and self-measurement of blood pressure are ways of counteracting the "white coat" effect which is the rise in blood pressure many patients experience in the presence of doctors. Thus, it is possible to define the cardiovascular risk of hypertension and identify the patients with the greatest chance of benefiting from antihypertensive therapy. However, it must be realised that normotensive subjects during their everyday activities and becoming hypertensive in the doctor's surgery, may become hypertensive with time, irrespective of the means used to measure blood pressure. These patients should be followed up regularly even if the decision to treat has been postponed.