Local Buckling of Concrete Filled Rectangular Steel Tube with Longitudinal Stiffener under Axial Compression

Width-thickness ratio was an important parameter for designing Concrete Filled Rectangular Steel Tube (CFRST). Welding longitudinal stiffener on the internal wall of steel pipe could delay the local buckling, which increased the limit of width-thickness ratio. If there was not enough stiffener and its sectional dimension was too small, the local buckling of steel pipe would occur, inducing its bearing capacity seriously. If the stiffener sectional dimension was too large, concrete filled in steel tube would be broken up, which reduces its bearing capacity. To solve that problem, this paper studied local buckling of CFRST with longitudinal stiffener under axial compression and design of longitudinal stiffener. It established buckling analysis model, simplified local buckling analysis as calculating buckling load of thin plate clamped on loading side and unloading side under axial force. It deduced buckling load and buckling coefficient based on the principle of energy. The results showed that buckling mode depended on stiffening rigidity. Therefore, it put forward minimum stiffening rigidity ratio that controlled the stiffener design. This paper also came up with a formula to calculate minimum stiffening rigidity ratio. It provided guidance on designing number, sectional dimension and material performance

Early-life exposure to widespread environmental toxicants and maternal-fetal health risk:A focus on metabolomic biomarkers

Prenatal exposure to widespread environmental toxicants is detrimental to maternal health and fetal development. The effects of environmental toxicants on maternal and fetal metabolic profile changes have not yet been summarized. This systematic review aims to summarize the current studies exploring the association between prenatal exposure to environmental toxicants and metabolic profile alterations in mother and fetus. We searched the MEDLINE (PubMed) electronic database for relevant literature conducted up to September 18, 2019 with some key terms. From the initial 155 articles, 15 articles met the inclusion and exclusion criteria, and consist of highly heterogeneous research methods. Seven studies assessed the effects of multiple environmental pollutants (metals, organic pollutants, nicotine, air pollutants) on the maternal urine and blood metabolomic profile; five studies evaluated the effects of arsenic, polychlorinated biphenyls (PCBs), nicotine, and ambient fine particulate matter (PM2.5) on the cord blood metabolomic profile; and one study assessed the effects of smoking exposure on the amniotic fluid metabolomic profile. The alteration of metabolic pathways in these studies mainly involve energy metabolism, hormone metabolism, oxidative stress and inflammation. No population study investigated the association between environmental toxicants and placental metabolomics. This systematic review provides evidence that prenatal exposure to a variety of environmental pollutants can affect maternal and fetal metabolomic characteristics. Integration of environmental toxicant exposure and metabolomics data in maternal-fetal samples is helpful to understand the interaction between toxicants and metabolites, so as to reveal the pathogenesis of fetal disease or diseases of fetal origin

Alterations in platelet indices link polycyclic aromatic hydrocarbons toxicity to low-grade inflammation in preschool children

Background: Environmental exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) can disturb the immune response. However, the effect of PAHs on low-grade inflammation related to platelets in humans is unknown. Objectives: We investigated the association of PAH exposure with low-grade inflammation and platelet parameters in healthy preschoolers. Methods: The present study recruited 239 participants, aged 2-7 years, from an electronic-waste (e-waste)-exposed (n = 118) and a reference (n = 121) area. We measured ten urinary PAH metabolites, four types of immune cells and cytokines, and seven platelet parameters, and compared their differences between children from the two groups. Spearman correlation analysis was performed to explore the potential risk factors for PAH exposure and the associations between urinary monohydroxylated PAHs (OH-PAHs) and biological parameters. Associations between urinary PAH metabolites and platelet indices were analyzed using quantile regression models. Mediation analysis was used to understand the relationship between urinary total hydroxynaphthalene (Sigma OHNa) and interleukin (IL)-1 beta through seven platelet indices, as mediator variables. Results: We found higher urinary monohydroxylated PAH (OH-PAH) concentrations, especially 1-hydroxynaphthalene (1-OHNa) and 2-hydroxynaphthalene (2-OHNa), in children from the e-waste-exposed group than in the reference group. These were closely associated with child personal habits and family environment. A decreased lymphocyte ratio and increased pro-inflammatory cytokines, such as gamma interferon-inducible protein (IP)-10 and IL-1 beta, were found in the e-waste-exposed children. After adjustment for confounding factors, significantly negative correlations were found between levels of mean platelet volume (MPV), platelet distribution width (PDW), platelet-large cell ratio (P-LCR) and ratio of mean platelet volume to platelet count (MPVP) and OH-PAHs. In addition, Sigma OHNa was positively associated with IL-1 beta mediated through MPV, PDW, P-LCR, and ratio of platelet count to lymphocyte count (PLR). Conclusions: Platelet indices were significantly associated with the changes in urinary OH-PAH levels, which may can be regarded as effective biomarkers of low-grade inflammation resulting from low PAH exposure in healthy children

Relations of blood lead levels to echocardiographic left ventricular structure and function in preschool children

Lead (Pb) has been proved to exert adverse effect on human cardiovascular system. However, the cardiotoxicity of Pb on children is still unclear. The aim of this study was to evaluate left ventricular (LV) structure and function, by using echocardiographic indices, in order to elucidate the effect of Pb on low-grade inflammation related to left ventricle in healthy preschool children. We recruited a total of 486 preschool children, 310 from Guiyu (e-waste-exposed area) and 176 from Haojiang (reference area). Blood Pb levels, complete blood counts, and LV parameters were evaluated. Associations between blood Pb levels and LV parameters and peripheral leukocyte counts were analyzed using linear regression models. The median blood level of Pb and the counts of white blood cells (WBCs), monocytes, and neutrophils were higher in exposed group. In addition, the exposed group showed smaller left ventricle (including interventricular septum, LV posterior wall, and LV mass index) and impaired LV systolic function (including LV fractional shortening and LV ejection fraction) regardless gender. After adjustment for confounding factors, elevated blood Pb levels were significantly associated with higher counts of WBCs and neutrophils, and lower levels of LV parameters. Furthermore, counts of WBCs, monocytes, and neutrophils were negatively correlated with LV parameters. Taken together, smaller left ventricle and impaired systolic function were found in e-waste-exposed children and associated with chronic low-grade inflammation and elevated blood Pb levels. It indicates that the heart health of e-waste-exposed children is at risk due to the long-term environmental chemical insults. (C) 2020 Elsevier Ltd. All rights reserved

E-waste polycyclic aromatic hydrocarbon (PAH) exposure leads to child gut-mucosal inflammation and adaptive immune response

Polycyclic aromatic hydrocarbon (PAH) exposure alters immunological responses. Research concerning PAH exposure on intestinal immunity of children in electronic waste (e-waste) areas is scarce. The aim of this study was to evaluate the effects of polycyclic aromatic hydrocarbon (PAH) pollutants on intestinal mucosal immunity of children in e-waste areas. Results showed higher hydroxylated PAH (OH-PAH) concentrations in e-waste-exposed children, accompanied with higher sialyl Lewis A (SLA) level, absolute lymphocyte and monocyte counts, decreased of percentage of CD4(+) T cells, and had a higher risk of diarrhea. OH-PAH concentrations were negative with child growth. 1-OHNap mediated through WBCs, along with 1-OHPyr, was correlated with an increase SLA concentration. 2-OHFlu, 1-OHPhe, 2-OHPhe, 1-OHPyr, and 6-OHChr were positively correlated with secretory immunoglobulin A (sIgA) concentration. Our results indicated that PAH pollutants caused inflammation, affected the intestinal epithelium, and led to transformation of microfold cell (M cell). M cells initiating mucosal immune responses and the subsequent increasing sIgA production might be an adaptive immune respond of children in the e-waste areas. To our knowledge, this is the first study of PAH exposure on children intestinal immunity in e-waste area, showing that PAH exposure plays a negative role in child growth and impairs the intestinal immune function

Increased intestinal permeability with elevated peripheral blood endotoxin and inflammatory indices for e-waste lead exposure in children

Lead (Pb) entering the body through different channels can damage the function of intestinal mucosal barrier and cause the body stressful inflammatory response to enhance. This study conducted a cross-sectional study to investigate the effects of Pb exposure on intestinal permeability in children by measuring the level of bacterial endotoxin and index of inflammatory cell types in peripheral blood. From November to December 2018, we recruited 187 participants aged 3-6 years by stratified randomization, from an electronic-waste-exposed group (n = 82) and a referent group (n = 105). General demographic information, past history of the digestive system in child, and family situation were informed by children's guardians with questionnaires. Children in the exposed group showed lower weight, height, and body mass index while more diarrhea in a month. Blood Pb and plasma endotoxin were elevated in exposed children than referent children and the positive relationship between them was shown in all children [B (95% CI): 0.072 (0.008, 0.137), P = 0.033]. Peripheral monocyte counts and leukotriene B-4 (LTB4) levels were significantly increased in the exposed group. Endotoxin levels were positively correlated with neutrophils, monocytes, and LTB4 [B (95% CI): 0.054 (0.015, 0.093), 0.018 (0.005, 0.031), and 0.049 (0.011, 0.087), respectively, P < 0.05]. To sum up, the exposed children showed lower physical growth levels, poorer gut health, and increased intestinal permeability, which was related to high blood Pb and peripheral inflammatory indices. These results suggest the possible adverse impact of environmental Pb exposure on the intestinal health of children

Elevated expression of AhR and NLRP3 link polycyclic aromatic hydrocarbon exposure to cytokine storm in preschool children

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs), as a group of persistent organic pollutants, are linked to impaired immune function and low-grade inflammation in adults and children. However, the potential of PAHs to lead to a cytokine storm associated with AhR (aryl hydrocarbon receptor) and NLRP3 (NLR family pyrin domain containing 3) in humans has been poorly studied. OBJECTIVES: We aimed to investigate the associations between PAH exposure, AhR and NLRP3 expression, and cytokines associated with a cytokine storm in healthy preschoolers. METHODS: Basic demographic surveys and physical examinations were conducted on 248 preschoolers from an electronic waste (e-waste) recycling area (Guiyu, n = 121) and a reference area (Haojiang, n = 127). Ten urinary PAH metabolite (OH-PAH) concentrations were measured. We also measured the expression levels of AhR and NLRP3 and seventeen serum cytokine levels. RESULTS: The concentrations of multiple OH-PAHs were significantly higher in the exposed group than those in the reference group, especially 1-hydroxynaphthalene (1-OH-Nap) and 2-hydroxynaphthalene (2-OH-Nap). PAH exposure was closely related to a child's living environment and hygiene habits. Expression levels of AhR and NLRP3 were significantly higher in the exposed group than in the reference group. Similarly, serum IL-1β, IL-4, IL-5, IL-10, IL-12p70, IL-13, IL-17A, IL-18, IL-22, IL-23, and IFN-γ levels were notably higher in the e-waste-exposed children than in the reference children. After adjusting for age, gender, BMI, family income, parental education level, and second-hand smoke exposure, we found that increased PAH exposure was associated with higher AhR and NLRP3 expression and elevated IL-4, IL-10, IL-12p70, IL-18, IL-22, IL-23, TNF-α, and IFN-γ levels. The associations between PAH exposure and IL-1β, IL-18, IFN-γ, and TNF-β were mediated by NLRP3 expression, and the relationships between PAH exposure and IL-4, IL-10, IL-12p70, IL-22, IL-23, and TNF-α were mediated by AhR expression. CONCLUSIONS: Our findings suggest that the association between PAH exposure and a cytokine storm may be mediated by AhR and NLRP3 expression among preschoolers

A Targeted Lipidomic Reveals CYP450-Derived Oxylipin Linked to the Inflammatory Response by Polycyclic Aromatic Hydrocarbon Exposure in Children

Polycyclic aromatic hydrocarbon (PAH) exposure is a cause of chronic inflammation. The effect of PAHs on bioactive lipid mediators involved in the inflammatory process remains largely unknown. This study measured ten urinary monohydroxy-PAHs (OH-PAHs), 54 plasma oxylipins, and inflammation-related markers. Children with high PAH exposure had higher levels of ten OH-PAHs, (±)18-HETE, 19(S)-HETE, 5,6-DiHETrE, 9,10-DiHOME, more monocytes, interleukin (IL)-10, tumor necrosis factor (TNF)-α and IL-6 than those with low PAH exposure (all p &lt; 0.05). The ƩOH-PAHs were inversely correlated to the levels of anti-inflammatory oxylipins, including 5,6-EET (p for trend = 0.007), 11,12-EET (p for trend = 0.035), 14,15-EET (p for trend = 0.022), and 16(17)-EpDPE (p for trend = 0.043), but positively associated with pro-inflammatory 9,10-DiHOME (p for trend &lt; 0.001). Mediation analyses indicated that cytochrome P450 (CYP)-derived 9,10-DiHOME mediated a separate 42.7%, 31.1%, 57.8%, and 38.5% of the associations between OH-PAHs and monocytes, IL-6, IL-10, TNF-α (p = 0.017, 0.014, 0.005 and 0.012, respectively). Our study suggests that CYP-derived oxylipins can be considered sensitive lipid mediators to signal the early inflammation response to PAH exposure.</p