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Background: Both short sleep duration and sleep-disordered breathing (SDB) are associated with poor neurocognitive development. However, the co-contributions of short sleep duration and SDB on neurodevelopment in pre-school children are relatively unknown.Methods: We assessed both sleep duration and SDB by quarterly questionnaire from three months to two years of age among Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort participants. Group-based modeling determined trajectories of total, daytime, and nighttime sleep duration and SDB. Linear regression was used to assess the impact of sleep duration and SDB trajectories on cognitive (primary outcome) and language (secondary) development at two years of age as assessed by the Bayley Scale of Infant Development (BSID-III) (mean 100; standard deviation of 15).Results: Of the 822 CHILD Edmonton participants, 703 (86%) were still enrolled at two years of age with 593 having BSID-III data at two years of age. Trajectory analysis identified four total sleep durations phenotypes [short sleepers (17.9%), decline to short sleepers (21.1%), intermediate sleepers (36.9%) and long sleepers (24.1%)]. Compared to children with intermediate sleep durations, short sleepers had a 5.2-point lower cognitive development score at two years of age [standard error (SE) 1.7; p = 0.002]. Nocturnal sleep duration, compared to daytime sleep duration had the greatest effect on cognitive development. We also identified three SDB symptom trajectories [early-onset SDB (15.7%), late-onset SDB (14.2%), and persistent SDB (5.3%)] and 79.5% of children had no SDB symptoms. Children with persistent SDB also had a 5.3-point lower language score (SE 2.7; p = 0.05) compared to children with no SDB. SDB trajectories were not associated with cognitive development.Conclusion: In a population-representative birth cohort study, both short sleep duration and SDB were associated with adverse neurodevelopment at two years of age. Children with short nighttime sleep duration had lowered cognitive and language scores and children with persistent SDB also had lower language scores. [ABSTRACT FROM AUTHOR]

In contrast to other environmental allergens, the association with atopic dermatitis was present for Fel d 1, which may suggest that the skin is an important route of sensitization for this allergen. GLO:1X5/01dec19:all13927-fig-0002.jpg PHOTO (COLOR): Hierarchical clustering performed on patient sensitization profiles and allergen components indicating clusters by allergen source and biochemical family (sensitized: N = 37; nonsensitized: N = 18). In conclusion, we provide data describing a potentially high-risk preschool asthma cohort in Canada using a comprehensive approach capturing sensitization to allergens of paramount importance. By applying both allergen extracts and components, we identified that peanut and animal allergens from cat and dog were major allergen sources in this North American cohort of preschool asthmatics. [Extracted from the article]

Secretory Immunoglobulin A (sIgA) plays a critical role to infant gut mucosal immunity. Delayed IgA production is associated with greater risk of allergic disease. Murine models of stressful events during pregnancy and infancy show alterations in gut immunity and microbial composition in offspring, but little is known about the stress-microbiome-immunity pathways in humans. We investigated differences in infant fecal sIgA concentrations according to the presence of maternal depressive symptoms during and after pregnancy. A subsample of 403 term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) cohort were studied. Their mothers completed the Center of Epidemiologic Studies Depression Scale when enrolled prenatally and again postpartum. Quantified by Immundiagnostik sIgA ELISA kit, sIgA from infant stool was compared across maternal depressive symptom categories using Mann-Whitney U-tests and logistic regression models that controlled for various covariates. Twelve percent of women reported clinically significant depressive symptoms only prenatally, 8.7% had only postpartum symptoms and 9.2% had symptoms both pre and postnatally. Infants born to mothers with pre and postnatal symptoms had significantly lower median sIgA concentrations than those in the reference group (4.4 mg/g feces vs. 6.3 mg/g feces; p = 0.033). The odds for sIgA concentrations in the lowest quartile was threefold higher (95% CI: 1.25–7.55) when mothers had pre and postnatal symptoms, after controlling for breastfeeding status, infant age, antibiotics exposure and other covariates. Postnatal symptoms were not associated with fecal sIgA, independently of breastfeeding status. Infants born to mothers with depressive symptoms appear to have lower fecal sIgA concentrations, predisposing them to higher risk for allergic disease. [ABSTRACT FROM AUTHOR]

Background The effect of infant feeding practices on the development of food allergy remains controversial. We examined the relationship between timing and patterns of food introduction and sensitization to foods at age 1 year in the Canadian Healthy Infant Longitudinal Development ( CHILD) birth cohort study. Methods Nutrition questionnaire data prospectively collected at age 3, 6, 12, 18, and 24 months were used to determine timing of introduction of cow's milk products, egg, and peanut. At age 1 year, infants underwent skin prick testing to cow's milk, egg white, and peanut. Logistic regression models were fitted to assess the impact of timing of food exposures on sensitization outcomes, and latent class analysis was used to study patterns of food introduction within the cohort. Results Among 2124 children with sufficient data, delaying introduction of cow's milk products, egg, and peanut beyond the first year of life significantly increased the odds of sensitization to that food (cow's milk adj OR 3.69, 95% CI 1.37-9.08; egg adj OR 1.89, 95% CI 1.25-2.80; peanut adj OR 1.76, 95% CI 1.07-3.01). Latent class analysis produced a three-class model: early, usual, and delayed introduction. A pattern of delayed introduction, characterized by avoidance of egg and peanut during the first year of life, increased the odds of sensitization to any of the three tested foods (adj OR 1.78, 95% CI 1.26-2.49). Conclusions Avoidance of potentially allergenic foods during the first year of life significantly increased the odds of sensitization to the corresponding foods. [ABSTRACT FROM AUTHOR]

Changes in maternal innate immunity during healthy human pregnancy are not well understood. Whether basal immune status in vivo is largely unaffected by pregnancy, is constitutively biased towards an inflammatory phenotype (transiently enhancing host defense) or exhibits anti-inflammatory bias (reducing potential responsiveness to the fetus) is unclear. Here, in a longitudinal study of healthy women who gave birth to healthy infants following uncomplicated pregnancies within the Canadian Healthy Infant Longitudinal Development (CHILD) cohort, we test the hypothesis that a progressively altered bias in resting innate immune status develops. Women were examined during pregnancy and again, one and/or three years postpartum. Most pro-inflammatory cytokine expression, including CCL2, CXCL10, IL-18 and TNFα, was reduced in vivo during pregnancy (20–57%, p<0.0001). Anti-inflammatory biomarkers (sTNF-RI, sTNF-RII, and IL-1Ra) were elevated by ~50–100% (p<0.0001). Systemic IL-10 levels were unaltered during vs. post-pregnancy. Kinetic studies demonstrate that while decreased pro-inflammatory biomarker expression (CCL2, CXCL10, IL-18, and TNFα) was constant, anti-inflammatory expression increased progressively with increasing gestational age (p<0.0001). We conclude that healthy resting maternal immune status is characterized by an increasingly pronounced bias towards a systemic anti-inflammatory innate phenotype during the last two trimesters of pregnancy. This is resolved by one year postpartum in the absence of repeat pregnancy. The findings provide enhanced understanding of immunological changes that occur in vivo during healthy human pregnancy. [ABSTRACT FROM AUTHOR]

Background: The infant gut is rapidly colonized by microorganisms soon after birth, and the composition of the microbiota is dynamic in the first year of life. Although a stable microbiome may not be established until 1 to 3 years after birth, the infant gut microbiota appears to be an important predictor of health outcomes in later life. Methods: We obtained stool at one year of age from 173 white Caucasian and 182 South Asian infants from two Canadian birth cohorts to gain insight into how maternal and early infancy exposures influence the development of the gut microbiota. We investigated whether the infant gut microbiota differed by ethnicity (referring to groups of people who have certain racial, cultural, religious, or other traits in common) and by breastfeeding status, while accounting for variations in maternal and infant exposures (such as maternal antibiotic use, gestational diabetes, vegetarianism, infant milk diet, time of introduction of solid food, infant birth weight, and weight gain in the first year). Results: We demonstrate that ethnicity and infant feeding practices independently influence the infant gut microbiome at 1 year, and that ethnic differences can be mapped to alpha diversity as well as a higher abundance of lactic acid bacteria in South Asians and a higher abundance of genera within the order Clostridiales in white Caucasians. Conclusions: The infant gut microbiome is influenced by ethnicity and breastfeeding in the first year of life. Ethnic differences in the gut microbiome may reflect maternal/infant dietary differences and whether these differences are associated with future cardiometabolic outcomes can only be determined after prospective follow-up. [ABSTRACT FROM AUTHOR]

Asthma is a chronic disease of the airways affecting one in ten children in Westernized countries. Recently, our group showed that specific bacterial genera in early life are associated with atopy and wheezing in 1-year-old children. However, little is known about the link between the early life gut microbiome and the diagnosis of asthma in preschool age children. To determine the role of the gut microbiota in preschool age asthma, children up to 4 years of age enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) study were classified as asthmatic (n=39) or matched healthy controls (n=37). 16S rRNA sequencing and quantitative PCR (qPCR) were used to analyse the composition of the 3-month and 1-year gut microbiome of these children. At 3 months the abundance of the genus, Lachnospira (L), was decreased (P=0.008), whereas the abundance of the species, Clostridium neonatale (C), was increased (P=0.07) in asthmatics. Quartile analysis of stool composition at 3-months revealed a negative association between the ratio of these two bacteria (L/C) and asthma risk by 4 years of age [quartile 1: odds ratio (OR)=15, P=0.02, CI (confidence interval) =1.8-124.7; quartile 2: OR=1.0, ns; quartile 3: OR=0.37, ns]. We conclude that opposing shifts in the relative abundances of Lachnospira and C. neonatale in the first 3 months of life are associated with preschool age asthma, and that the L/C ratio may serve as a potential early life biomarker to predict asthma development. [ABSTRACT FROM AUTHOR]

Background: Canada is an ethnically diverse nation, which introduces challenges for health care providers tasked with providing evidence-based dietary advice.Objectives: We aimed to harmonize food-frequency questionnaires (FFQs) across 4 birth cohorts of ethnically diverse pregnant women to derive robust dietary patterns to investigate maternal and newborn outcomes.Methods: The NutriGen Alliance comprises 4 prospective birth cohorts and includes 4880 Canadian mother-infant pairs of predominantly white European [CHILD (Canadian Healthy Infant Longitudinal Development) and FAMILY (Family Atherosclerosis Monitoring In earLY life)], South Asian [START (SouTh Asian birth cohoRT)-Canada], or Aboriginal [ABC (Aboriginal Birth Cohort)] origins. CHILD used a multiethnic FFQ based on a previously validated instrument designed by the Fred Hutchinson Cancer Research Center, whereas FAMILY, START, and ABC used questionnaires specifically designed for use in white European, South Asian, and Aboriginal people, respectively. The serving sizes and consumption frequencies of individual food items within the 4 FFQs were harmonized and aggregated into 36 common food groups. Principal components analysis was used to identify dietary patterns that were internally validated against self-reported vegetarian status and externally validated against a modified Alternative Healthy Eating Index (mAHEI).Results: Three maternal dietary patterns were identified-"plant-based," "Western," and "health-conscious"-which collectively explained 29% of the total variability in eating habits observed in the NutriGen Alliance. These patterns were strongly associated with self-reported vegetarian status (OR: 3.85; 95% CI: 3.47, 4.29; r2 = 0.30, P < 0.001; for a plant-based diet), and average adherence to the plant-based diet was higher in participants in the fourth quartile of the mAHEI than in the first quartile (mean difference: 46.1%; r2 = 0.81, P < 0.001).Conclusion: Dietary data collected by using FFQs from ethnically diverse pregnant women can be harmonized to identify common dietary patterns to investigate associations between maternal dietary intake and health outcomes. [ABSTRACT FROM AUTHOR]

Colonization of infants with Clostridium difficile is on the rise. Although better tolerated by infants than adults, it is a risk factor for future allergic disease. The present study describes associations between infant fecal immunoglobulin A (IgA) and colonization with C. difficile in 47 infants enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) study. C. difficile colonization was observed in over half (53%) of the infants. Median IgA was lower in infants colonized with C. difficile (10.9 μg versus 25.5 μg per g protein; p = 0.18). A smaller proportion of infants with IgA in the highest tertile were colonized with C. difficile compared to the other tertiles (31.3% versus 64.5%, p = 0.03). In unadjusted analysis, odds of colonization with C. difficile was reduced by 75% (OR 0.25 95% CI 0.07, 0.91 p = 0.04) among infants with IgA in the highest tertile compared to those in the other tertiles. Following adjustment for parity, birth mode and breastfeeding, this association was even stronger (aOR 0.17, 95% CI 0.03, 0.94, p = 0.04). Our study provides evidence that high fecal IgA, independent of breastfeeding, is associated with reduced likelihood of C. difficile colonization in infancy. [ABSTRACT FROM AUTHOR]

The Canadian Healthy Infant Longitudinal Development birth cohort was designed to elucidate interactions between environment and genetics underlying development of asthma and allergy. Over 3600 pregnant mothers were recruited from the general population in four provinces with diverse environments. The child is followed to age 5 years, with prospective characterization of diverse exposures during this critical period. Key exposure domains include indoor and outdoor air pollutants, inhalation, ingestion and dermal uptake of chemicals, mold, dampness, biological allergens, pets and pests, housing structure, and living behavior, together with infections, nutrition, psychosocial environment, and medications. Assessments of early life exposures are focused on those linked to inflammatory responses driven by the acquired and innate immune systems. Mothers complete extensive environmental questionnaires including time-activity behavior at recruitment and when the child is 3, 6, 12, 24, 30, 36, 48, and 60 months old. House dust collected during a thorough home assessment at 3-4 months, and biological specimens obtained for multiple exposure-related measurements, are archived for analyses. Geo-locations of homes and daycares and land-use regression for estimating traffic-related air pollution complement time-activity-behavior data to provide comprehensive individual exposure profiles. Several analytical frameworks are proposed to address the many interacting exposure variables and potential issues of co-linearity in this complex data set. [ABSTRACT FROM AUTHOR]

Background: The role of traffic-related air pollution (TRAP) exposure in the development of allergic sensitization in children is unclear, and few birth cohort studies have incorporated spatiotemporal exposure assessment. Objectives: We aimed to examine the association between TRAP and atopy in 1-year-old children from an ongoing national birth cohort study in four Canadian cities. Methods: We identified 2,477 children of approximately 1 year of age with assessment of atopy for inhalant (Alternaria, Der p, Der f, cat, dog, cockroach) and food-related (milk, eggs, peanuts, soy) allergens. Exposure to nitrogen dioxide (NO2) was estimated from city-specific land use regression models accounting for residential mobility and temporal variability in ambient concentrations. We used mixed models to examine associations between atopy and exposure during pregnancy and the first year of life, including adjustment for covariates (maternal atopy, socioeconomic status, pets, mold, nutrition). We also conducted analyses stratified by time-location patterns, daycare attendance, and modeled home ventilation. Results: Following spatiotemporal adjustment, TRAP exposure after birth increased the risk for development of atopy to any allergens [adjusted odds ratio (aOR) per 10 μg/m3 NO2 = 1.16; 95% CI: 1.00, 1.41], but not during pregnancy (aOR = 1.02; 95% CI: 0.86, 1.22). This association was stronger among children not attending daycare (aOR = 1.61; 95% CI: 1.28, 2.01) compared with daycare attendees (aOR = 1.05; 95% CI: 0.81, 1.28). Trends to increased risk were also found for food (aOR = 1.17; 95% CI: 0.95, 1.47) and inhalant allergens (aOR = 1.28; 95% CI: 0.93, 1.76). Conclusion: Using refined exposure estimates that incorporated temporal variability and residential mobility, we found that traffic-related air pollution during the first year of life was associated with atopy. [ABSTRACT FROM AUTHOR]

Background The lung clearance index (LCI) measured by multiple-breath washout (MBW) has been proposed as an outcome for clinical trials; however, MBW is time consuming and LCI can be affected by breathing pattern. We aimed to evaluate moment ratios and abbreviated LCI in school-aged children with mild-to-moderate CF lung disease. Methods Using existing data from three studies we assessed the sensitivity of moment ratios and abbreviated LCIs to (i) detect mild-to-moderate CF lung disease and (ii) detect treatment effects after 4 weeks of hypertonic saline or dornase alfa inhalation. MBW was measured by respiratory mass spectrometry using 4% ""sulphur hexafluoride as a tracer gas. Results Compared to the traditional LCI, moment ratios and abbreviated LCIs were similarly sensitive to detect CF lung disease. Moment ratios consistently demonstrated treatment effects, whereas abbreviated LCIs were less sensitive. Conclusions Both moment ratios and abbreviated LCI are suitable to differentiate health from disease. Sensitivity is decreased for abbreviated LCIs in interventional studies in mild CF lung disease. [ABSTRACT FROM AUTHOR]

L-Arginine metabolism including the nitric oxide (NO) synthase and arginase pathways is important in the maintenance of airways function. We have previously reported that accumulation of asymmetric dimethylarginine (ADMA) in airways, resulting in changes in L-arginine metabolism, contributes to airways obstruction in asthma and cystic fibrosis. Herein, we assessed L-arginine metabolism in airways of patients with chronic obstructive pulmonary disease (COPD). Lung function testing, measurement of fractional exhaled NO (FeNO) and sputum NO metabolites, as well as quantification of L-arginine metabolites (L-arginine, L-ornithine, L-citrulline, ADMA and symmetric dimethylarginine) using liquid chromatography-mass spectrometry (LC-MS) were performed. Concentrations of L-ornithine, the product of arginase activity, correlated directly with L-arginine and ADMA sputum concentrations. FeNO correlated directly with pre- and post-bronchodilator forced expiratory volume in one second (FEV1). Sputum arginase activity correlated inversely with total NO metabolite (NOx) and nitrite concentrations in sputum, and with pre- and post-bronchodilator FEV1. These findings suggest that ADMA in COPD airways results in a functionally relevant shift of L-arginine breakdown by the NO synthases towards the arginase pathway, which contributes to airway obstruction in these patients. [ABSTRACT FROM AUTHOR]

Background: Exposure to traffic-related air pollution (TRAP) can adversely impact health but epidemiologic studies are limited in their abilities to assess long-term exposures and incorporate variability in indoor pollutant infiltration. Methods: In order to examine settled house dust levels of hopanes, engine lubricating oil byproducts found in vehicle exhaust, as a novel TRAP exposure measure, dust samples were collected from 171 homes in five Canadian cities and analyzed by gas chromatography-mass spectrometry. To evaluate source contributions, the relative abundance of the highest concentration hopane monomer in house dust was compared to that in outdoor air. Geographic variables related to TRAP emissions and outdoor NO2 concentrations from city-specific TRAP land use regression (LUR) models were calculated at each georeferenced residence location and assessed as predictors of variability in dust hopanes. Results: Hopanes relative abundance in house dust and ambient air were significantly correlated (Pearson's r=0.48, p<0.05), suggesting that dust hopanes likely result from traffic emissions. The proportion of variance in dust hopanes concentrations explained by LUR NO2 was less than 10% in Vancouver, Winnipeg and Toronto while the correlations in Edmonton and Windsor explained 20 to 40% of the variance. Modeling with household factors such as air conditioning and shoe removal along with geographic predictors related to TRAP generally increased the proportion of explained variability (10-80%) in measured indoor hopanes dust levels. Conclusions: Hopanes can consistently be detected in house dust and may be a useful tracer of TRAP exposure if determinants of their spatiotemporal variability are well-characterized, and when home-specific factors are considered. [ABSTRACT FROM AUTHOR]

Background: The lung clearance index (LCI), measured by multiple breath washout (MBW), reflects global ventilation inhomogeneity and is a sensitive marker of early cystic fibrosis (CF) lung disease. Current evidence is based on a customized mass spectrometry system that uses sulfur hexafluoride (SF6) as a tracer gas, which is not widely available. Nitrogen (N2) washout may be better suited for clinical use and multi-center trials. Objective: To compare the results obtained from a N2 washout system to those generated by the SF6 based system in healthy children and children with CF. Methods: Children with CF were recruited from outpatient clinics; healthy children were recruited from the Research4Kids online portal. Participants performed MBWSF6 (Amis 2000, Innovision, Denmark) and MBWN2 (ExhalyzerD, EcoMedics, Switzerland) in triplicate, in random order on the same day. Agreement between systems was assessed by Bland-Altman plot. Results: Sixty-two healthy and 61 children with CF completed measurements on both systems. In health there was good agreement between systems (limits of agreement −0.7 to 1.9); on average N2 produced higher values of LCI (mean difference 0.58 (95% CI 0.42 to 0.74)). In CF the difference between systems was double that in health with a clear bias towards disproportionately higher LCIN2 compared to LCISF6 at higher mean values of LCI. Conclusion: LCIN2 and LCISF6 have similar discriminative power and intra-session repeatability but are not interchangeable. MBWN2 offers a valid new tool to investigate early obstructive lung disease in CF, but requires independent normative values. [ABSTRACT FROM AUTHOR]

Studies have demonstrated an association between phthalate exposure and childhood asthma, although results have been inconsistent. No epidemiological studies have examined exposure during the first year of life. To investigate the association between phthalate exposures in the home environment during the first year of life, and subsequent development of childhood asthma and related symptoms. This study used a case-cohort design including 436 randomly selected children and all additional cases of asthma at 5 years (n total = 129) and recurrent wheeze between 2 and 5 years (n total = 332) within the CHILD Cohort Study, a general population Canadian birth cohort of 3455 children. Phthalate exposure was assessed using house dust samples collected during a standardized home visit when children were 3-4 months of age. All children were assessed by specialist clinicians for asthma and allergy at 1, 3 and 5 years. Logistic regression was used to assess the association between exposure to five phthalates and asthma diagnosis at 5 years, and recurrent wheeze between 2 and 5 years, with further stratification by wheeze subtypes (late onset, persistent, transient) based on the timing of onset and persistence of wheeze symptoms. Di(2-ethylhexyl) phthalate (DEHP) had the highest concentration in dust (median subcohort = 217 μg/g), followed by benzyl butyl phthalate (BzBP) (20 μg/g). A nearly four-fold increase in risk of developing asthma was associated with the highest concentration quartile of DEHP (OR = 3.92, 95% CI: 1.87–8.24) including a positive dose-response relationship. A two-fold increase in risk of recurrent wheeze was observed across all quartiles compared to the lowest quartile of DEHP concentrations. Compared to other wheeze subtypes, stronger associations for DEHP were observed with the late onset wheezing subtype, while stronger associations for di-iso-butyl phthalate (DiBP) and BzBP were observed with the transient subtype. DEHP exposure at 3-4 months, at concentrations lower than other studies that reported an association, were associated with increased risks of asthma and recurrent wheeze among children at 5 years. These findings suggest the need to assess whether more stringent regulations are required to protect children's health, which can be informed by future work exploring the main sources of DEHP exposure. • DEHP, BzBP, DnBP, DiBP and DEP were detected in nearly all house dust samples. • Early life DEHP exposure was associated with a large increased risk of asthma at 5 years. • Early life DEHP exposure associated with increased risk of recurrent wheeze between 2 and 5 years. • Increased risk with DEHP observed at concentrations lower than other studies. [ABSTRACT FROM AUTHOR]

• Proximity to natural urban environments – their vegetation, soil or water – may be beneficial for early life microbiota. • Tested influence of a natural environment within 500 m of a home residence on infant gut microbiota at age 4 months. • Proximity to a natural environment plus pet ownership reduced microbial diversity of infants not breastfed. • Notable changes in gut microbial composition included enrichment of Proteobacteria that are commonly found in vegetation. The biodiversity hypothesis that contact with natural environments (e.g. native vegetation) and biodiversity, through the influence of environmental microbes, may be beneficial for human commensal microbiota has been insufficiently tested. We aimed to study the association between living near natural environments in the urban context, and gut microbiota diversity and composition in young infants. Based on data linkage between the unique Urban Primary Land and Vegetation Inventory (uPLVI) for the city of Edmonton and 355 infants in the CHILD Cohort Study, infant exposure to natural environments (any and specific types, yes/no) was determined within 500 m and 1000 m of their home residence. Gut microbiota composition and diversity at age 4 months was assessed in infant fecal samples. Adjusted for covariates, we observed a reduced odds of high microbial alpha-diversity in the gut of infants exposed to any natural environment within 500 m [Shannon index aOR (95%CI) = 0.63 (0.40, 0.98) and Simpson index = 0.63 (0.41, 0.98)]. In stratified analyses, these associations remained only among infants not breastfed or living with household pets. When doubly stratifying by these variables, the reduced likelihood of high alpha-diversity was present only among infants who were not breastfed and lived with household pets [9% of the study population, Shannon index = 0.07 (0.01, 0.49) and Simpson index = 0.11 (0.02, 0.66)]. Differences in beta-diversity was also seen (p = 0.04) with proximity to a nature space in not breastfed and pets-exposed infants. No associations were observed among infants who were fully formula-fed but without pets at home. When families and their pets had close access to a natural environment, Verrucomicrobiales colonization was reduced in the gut microbiota of formula-fed infants, the abundance of Clostridiales was depleted, whereas the abundance of Enterobacteriales was enriched. Our double-stratified results indicate that proximity to a natural environment plus pet ownership has the capacity to alter the gut microbiota of formula-fed infants. Further research is needed to replicate and better interpret these results, as well as to understand their health consequences. [ABSTRACT FROM AUTHOR]

Background: A growing number of studies observe associations between the amount of green space around a mother's home and positive birth outcomes; however, the robustness of this association and potential pathways of action remain unclear. Objectives: To examine associations between mother's residential green space and term birth weight within the Canadian Healthy Infant Longitudinal Development (CHILD) study and examine specific hypothesized pathways. Methods: We examined 2510 births located in Vancouver, Edmonton, Winnipeg, and Toronto Canada. Green space was estimated around mother's residences during pregnancy using Landsat 30 m normalized difference vegetation index (NDVI). We examined hypothesized pathways of: (1) reduction of environmental exposure; (2) built environment features promoting physical activity; (3) psychosocial conditions; and (4) psychological influences. Linear regression was used to assess associations between green space and term birth weight adjusting first for a comprehensive set of confounding factors and then incrementally for pathway variables. Results: Fully adjusted models showed non-statistically significant increases in term birth weight with increasing green space. For example, a 0.1 increase in NDVI within 500 m was associated with a 21.5 g (95% CI − 4.6, 47.7) increase in term birth weight. Associations varied by city and were most robust for high-density locations. For the two largest cities (Vancouver and Toronto), we observed an increase in birth weight of 41.2 g (95% CI 7.8, 74.6) for a 0.1 increase in NDVI within 500 m. We did not observe substantial reductions in the green space effect on birth weight when adjusting for pathway variables. Conclusion: Our results highlight the need to further characterize the interactions between green space, urban density and climate related factors as well as the pathways linking residential green space to birth outcomes. [ABSTRACT FROM AUTHOR]

Background: Exposure to traffic-related air pollution (TRAP) can adversely impact health but epidemiologic studies are limited in their abilities to assess long-term exposures and incorporate variability in indoor pollutant infiltration.Methods: In order to examine settled house dust levels of hopanes, engine lubricating oil byproducts found in vehicle exhaust, as a novel TRAP exposure measure, dust samples were collected from 171 homes in five Canadian cities and analyzed by gas chromatography-mass spectrometry. To evaluate source contributions, the relative abundance of the highest concentration hopane monomer in house dust was compared to that in outdoor air. Geographic variables related to TRAP emissions and outdoor NO2 concentrations from city-specific TRAP land use regression (LUR) models were calculated at each georeferenced residence location and assessed as predictors of variability in dust hopanes.Results: Hopanes relative abundance in house dust and ambient air were significantly correlated (Pearson's r=0.48, p<0.05), suggesting that dust hopanes likely result from traffic emissions. The proportion of variance in dust hopanes concentrations explained by LUR NO2 was less than 10% in Vancouver, Winnipeg and Toronto while the correlations in Edmonton and Windsor explained 20 to 40% of the variance. Modeling with household factors such as air conditioning and shoe removal along with geographic predictors related to TRAP generally increased the proportion of explained variability (10-80%) in measured indoor hopanes dust levels.Conclusions: Hopanes can consistently be detected in house dust and may be a useful tracer of TRAP exposure if determinants of their spatiotemporal variability are well-characterized, and when home-specific factors are considered. [ABSTRACT FROM AUTHOR]