Summary
Background
Culture‐dependent methods have shown that meconium, the newborn's first intestinal discharge, is not sterile, but the diversity of bacteria present in this material needs to be ...further characterized by means of more sensitive molecular techniques.
Objective
Our aims were to characterize molecularly the meconium microbiota in term infants, to assess whether it contributes to the future microbiota of the infants’ gastrointestinal tract, and to evaluate how it relates to lifestyle variables and atopy‐related conditions.
Methods
We applied high‐throughput pyrosequencing of the 16S rRNA gene to study the meconium microbiota in twenty term newborns from a Spanish birth cohort. For comparison, we characterized the microbiota in fecal samples from seven pregnant women days before delivery and in two series of infant samples spanning the first seven months of life. We also compared our data with vaginal and skin microbiota characterized in independent studies. Different types of meconium microbiota were defined based on taxonomic composition and abundance and their associations with different factors were statistically evaluated.
Results
The meconium microbiota differs from those in adult feces, vagina and skin, but resembles that of fecal samples from young infants. Meconium samples clustered into two types with different bacterial diversity, richness and composition. One of the types was less diverse, dominated by enteric bacteria and associated with a history of atopic eczema in the mother (P = 0.038), whereas the second type was dominated by lactic acid bacteria and associated with respiratory problems in the infant (P = 0.040).
Conclusions & Clinical Relevance
Our findings suggest that the meconium microbiota has an intrauterine origin and participates in gut colonization. Although based on a small population sample, our association analyses also suggest that the type of bacteria detected in meconium is influenced by maternal factors and may have consequences for childhood health.
Weather-related health effects have attracted renewed interest because of the observed and predicted climate change. The authors studied the short-term effects of cold weather on mortality in 15 ...European cities. The effects of minimum apparent temperature on cause- and age-specific daily mortality were assessed for the cold season (October–March) by using data from 1990–2000. For city-specific analysis, the authors used Poisson regression and distributed lag models, controlling for potential confounders. Meta-regression models summarized the results and explored heterogeneity. A 1°C decrease in temperature was associated with a 1.35% (95% confidence interval (CI): 1.16, 1.53) increase in the daily number of total natural deaths and a 1.72% (95% CI: 1.44, 2.01), 3.30% (95% CI: 2.61, 3.99), and 1.25% (95% CI: 0.77, 1.73) increase in cardiovascular, respiratory, and cerebrovascular deaths, respectively. The increase was greater for the older age groups. The cold effect was found to be greater in warmer (southern) cities and persisted up to 23 days, with no evidence of mortality displacement. Cold-related mortality is an important public health problem across Europe. It should not be underestimated by public health authorities because of the recent focus on heat-wave episodes.
Maternal smoking during pregnancy increases childhood asthma risk, but health effects in children of nonsmoking mothers passively exposed to tobacco smoke during pregnancy are unclear. We examined ...the association of maternal passive smoking during pregnancy and wheeze in children aged ≤2 years.Individual data of 27 993 mother-child pairs from 15 European birth cohorts were combined in pooled analyses taking into consideration potential confounders.Children with maternal exposure to passive smoking during pregnancy and no other smoking exposure were more likely to develop wheeze up to the age of 2 years (OR 1.11, 95% CI 1.03-1.20) compared with unexposed children. Risk of wheeze was further increased by children's postnatal passive smoke exposure in addition to their mothers' passive exposure during pregnancy (OR 1.29, 95% CI 1.19-1.40) and highest in children with both sources of passive exposure and mothers who smoked actively during pregnancy (OR 1.73, 95% CI 1.59-1.88). Risk of wheeze associated with tobacco smoke exposure was higher in children with an allergic versus nonallergic family history.Maternal passive smoking exposure during pregnancy is an independent risk factor for wheeze in children up to the age of 2 years. Pregnant females should avoid active and passive exposure to tobacco smoke for the benefit of their children's health.
•This review studied the effects of OP pesticide exposure on child neurodevelopment.•Prenatal exposure was associated with negative effects on child mental development.•Evidence on postnatal exposure ...effects on child neurodevelopment is less consistent.•The high variability of methodologies across studies made comparisons difficult.•Standardised methodologies are needed to perform quantitative meta-analysis.
Agricultural and residential use of organophosphate (OP) pesticides has increased in recent decades after banning some persistent pesticides. Although there is evidence of the effects of OPs on neurodevelopment and behaviour in adults, limited information is available about their effects in children, who might be more vulnerable to neurotoxic compounds. This paper was aimed at analysing the scientific evidence published to date on potential neurodevelopmental and behavioural effects of prenatal and postnatal exposure to OPs. A systematic review was undertaken to identify original articles published up to December 2012 evaluating prenatal or postnatal exposure to OPs in children and effects on neurodevelopment and/or behaviour. Articles were critically compared, focusing on the methodology used to assess exposure and adverse effects, as well as potential contributing factors that may modify both exposure and outcomes, such as genetic susceptibility to certain enzymes involved in OPs metabolisation (e.g. paraoxonase-1) and gender differences. Twenty articles met the inclusion criteria, 7 of which evaluated prenatal exposure to OPs, 8 postnatal exposure and 5 both pre- and postnatal exposure. Most of the studies evaluating prenatal exposure observed a negative effect on mental development and an increase in attention problems in preschool and school children. The evidence on postnatal exposure is less consistent, although 2 studies found an increase in reaction time in schoolchildren. Some paraoxonase-1 polymorphisms could enhance the association between OPs exposure and mental and psychomotor development. A large variability in epidemiological designs and methodologies used for assessing exposure and outcome was observed across the different studies, which made comparisons difficult. Prenatal and to a lesser extent postnatal exposure to OPs may contribute to neurodevelopmental and behavioural deficits in preschool and school children. Standardised methodologies are needed to allow results to be better compared and to perform a quantitative meta-analysis before drawing any final conclusions.
Rockfall is a phenomenon which, when uncontrolled, may cause extensive material damage and personal injury. One of the structures used to avoid accidents caused by debris flows or rockfalls is ...flexible barriers. The energy dissipating devices which absorb the energy generated by rock impact and reduce the mechanical stresses in the rest of the elements of the structure are an essential part of these kinds of structures. This document proposes an overview of the performance of energy dissipating devices, as well as of the role that they fulfil in the barrier. Furthermore, a compilation and a description of the dissipating elements found in the literature are proposed. Additionally, an analysis has been performed of the aspects taken into account in the design, such as experimental (quasi-static and dynamic) tests observing the variation of the behaviour curve depending on the test speed and numerical simulations by means of several finite element software packages.
•Seawater environment over composite material that are suitable for civil applications.•Seawater intake is linked to tensile and flexural strength degradation in GFC.•Fatigue performance of glass ...composites is similar in seawater environment than in air.
Glass fiber composites (GFRP) are common in civil engineering projects, but not in marine structures. One reason is that seawater effects degrade GFRP composites mechanical properties and interlaminar shear strength (ILSS). Here, influence of seawater environment is studied to determine the best composite materials for marine civil engineer applications, studying the influence of several factors in their mechanical properties. This is to determine safety factors to use in the design of structural calculations for marine applications. Glass/epoxy composites are the safest materials to use in marine civil structures as mechanical properties degradation becomes stabilized after moisture saturation level. UV and water cyclic analysis must be done to determine affection to transversal strength. Only vinylester GFRP has problems with biodegradation. GFRP fatigue performance is not influenced by seawater environment.
Vulnerability of the central nervous system to mercury is increased during early development. This study aimed to evaluate whether cord blood total mercury levels may have a negative effect on both ...mental and psychomotor development in a maternal-birth cohort from moderate-high fish consumption areas. Study subjects were 1,683 child participants in the INMA (Environment and Childhood) Project from 4 areas of Spain between 2003 and 2010. Cord blood total mercury levels were analyzed by atomic absorption spectrometry. Infant neurodevelopment was assessed around age 14 months by the Bayley Scales of Infant Development. Sociodemographic, lifestyle, and dietary information was obtained by questionnaire during pregnancy. The geometric mean of total mercury levels was 8.4 μg/L (95% confidence interval (CI): 8.1, 8.7). In multivariate analysis, a doubling in total mercury levels did not show an association with mental (β = 0.1, 95% CI: −0.68, 0.88) or psychomotor (β = −0.05, 95% CI: −0.79, 0.68) developmental delay; however, stratified findings by sex suggest a negative association between prenatal exposure to total mercury and psychomotor development among female infants (β = −1.09, 95% CI: −2.21, 0.03), although follow-up is required to confirm these results.
Organochlorine pesticides and polychlorinated biphenyls (PCBs) are consistently found in human tissues. Serum levels of organochlorine compounds (OC) in pregnant women in particular have raised ...concern about possible harm to humans in the early phases of physical and behavioural development. The objective of the present study was to evaluate the association between concentration of OCs in serum of two cohorts of pregnant women from Gipuzkoa and Sabadell in Spain and socioeconomic, reproductive and dietary variables. Concentration of polychlorinated biphenyls (PCBs: 28, 52, 101, 118, 138, 153 and 180), hexachlorobenzene (HCB), beta and gamma-hexachlorocyclohexane (
β-HCH and
γ-HCH), heptachlor epoxide, dichlorodiphenyl dichloroethylene (
p,p′-DDE) and dichlorodiphenyl trichloroethane (
p,p′-DDT) were measured in the serum of 1259 pregnant women. Associations between OCs and potential predictor variables were assessed using linear regression models adjusted for potential confounders.
The compounds most commonly found in the serum were
p,p′-DDE (99% of the samples) and PCB-153 (95% of the samples). Geometric means of serum concentrations (ng
g
−1 lipid) of organochlorine pesticides were 110.0, 19.1, and 33.5 for
p,p′-DDE,
β-HCH, and HCB respectively, while the geometric means of PCBs were 21.8, 38.9 and 26.9 for PCB 138, 153, and 180 respectively.
The levels of all OCs increased with age. BMI was positively associated with the concentration of organochlorine pesticides but inversely related to PCB concentrations. The serum levels of OCs fell only after a cumulative period of breastfeeding of over a year. Levels of PCBs were related to fish intake, but in general dietary factors did not improve the explained variability of the concentrations of OCs. Overall, the levels of OCs found in the study are at the lower end of the range reported in Spain and other countries.
An important point to consider in a brachytherapy dosimetry study is the phantom size involved in calculations or experimental measurements. As pointed out by Williamson Med. Phys. 18, 776–786 (1991) ...this topic has a relevant influence on final dosimetric results. Presently, one-dimensional (1-D) algorithms and newly-developed 3-D correction algorithms are based on physics data that are obtained under full scatter conditions, i.e., assumed infinite phantom size. One can then assume that reference dose distributions in source dosimetry for photon brachytherapy should use an unbounded phantom size rather than phantom-like dimensions. Our aim in this paper is to study the effect of phantom size on brachytherapy for radionuclide
137
Cs
,
192
Ir
,
125
I
and
103
Pd
,
mainly used for clinical purposes. Using the GEANT4 Monte Carlo code, we can ascertain effects on derived dosimetry parameters and functions to establish a distance dependent difference due to the absence of full scatter conditions. We have found that for
137
Cs
and
192
Ir
,
a spherical phantom with a 40 cm radius is the equivalent of an unbounded phantom up to a distance of 20 cm from the source, as this size ensures full scatter conditions at this distance. For
125
I
and
103
Pd
,
the required radius for the spherical phantom in order to ensure full scatter conditions at 10 cm from the source is
R=15
cm
.
A simple expression based on fits of the dose distributions for various phantom sizes has been developed for
137
Cs
and
192
Ir
in order to compare the dose rate distributions published for different phantom sizes. Using these relations it is possible to obtain radial dose functions for unbounded medium from bounded phantom ones.
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