Maternal Adiposity Influences Neonatal Brain Functional Connectivity

The neural mechanisms associated with obesity have been extensively studied, but the impact of maternal obesity on fetal and neonatal brain development remains poorly understood. In this study of full-term neonates, we aimed to detect potential neonatal functional connectivity alterations associated with maternal adiposity, quantified via body-mass-index (BMI) and body-fat-mass (BFM) percentage, based on seed-based and graph theoretical analysis using resting-state fMRI data. Our results revealed significant neonatal functional connectivity alterations in all four functional domains that are implicated in adult obesity: sensory cue processing, reward processing, cognitive control, and motor control. Moreover, some of the detected areas showing regional functional connectivity alterations also showed global degree and efficiency differences. These findings provide important clues to the potential neural basis for cognitive and mental health development in offspring of obese mothers and may lead to the derivation of imaging-based biomarkers for the early identification of risks for timely intervention

Effects of surface preparation on tribological behaviour of a ferritic stainless steel in hot rolling

Some defects on the surface of carbon steel do not need to be removed before hot rolling because the surface will be vigorously oxidised in a reheating environment. Thus the defects can be minimised by oxidising and then removed by the de-scaling process. The defects on the surface of ferritic stainless steels, however, are not easily removed by oxidation when a high chromium concentration is used. In this paper, a ferritic stainless steel grade 445 was selected as a research material. The effects of different surface features on oxidation and tribological behaviour in the hot rolling process were investigated. Three surface states were prepared, namely, smooth surface, surface with 45° grinding marks and surface with oscillation marks. The samples were put into an electric furnace at 1100 °C for reheating. Hot rolling tests were carried out on a 2-high Hille 100 experimental rolling mill. Rolling forces were measured, and the coefficient of friction was calculated and compared under various rolling parameters. It was found that the original surface profiles with grinding marks were still maintained during oxidation. The original oxide scale on the surface with oscillation marks caused the formation of irregular oxide nodules and the spallation of the oxide scale. Surface morphology and the reduction in thickness had a significant impact on the oxide scale integrity and coefficient of friction in the hot rolling process

Iodine speciation in aerosol particle samples collected over the sea between offshore China and the Arctic Ocean

Iodine species collected by an onboard PM10 particle sampling system during the Second Chinese National Arctic Research Expedition (July–September 2003) were measured using inductively coupled plasma mass spectrometry and ion chromatography-inductively coupled plasma mass spectrometry. Iodine (I−) was detected in all samples over the Arctic Ocean, whereas additional iodine species including insoluble iodine, soluble organic iodine plus I− were detected over the northwestern Pacific Ocean. The results suggest that the main form of iodine is different within the Arctic Ocean than it is outside. Enrichment factor values showed moderate enrichment of iodine in the northwestern Pacific, whereas a high enrichment factor was found in polar regions, implying sources other than sea salt. A potential explanation was ascribed to the role of sea ice melt in the Arctic and rapid growth of algae in seawater, which enhances the production of iodocarbon and air sea exchange. This was confirmed by the larger values of total iodine in 2008 than in 2003, with greater sea ice melt in the former year. In comparison with earlier reports, ratios of iodate to iodide (IO3−/I−) were much smaller than 1.0. These ratios were also different from modeling results, implying more complicated cycles of atmospheric iodine than are presently understood

Cryo-EM structures of lipopolysaccharide transporter LptB2FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism

Lipopolysaccharides (LPS) of Gram-negative bacteria are critical for the defence against cytotoxic substances and must be transported from the inner membrane (IM) to the outer membrane (OM) through a bridge formed by seven membrane proteins (LptBFGCADE). The IM component LptB2FG powers the process through a yet unclarified mechanism. Here we report three high-resolution cryo-EM structures of LptB2FG alone and complexed with LptC (LptB2FGC), trapped in either the LPS- or AMP-PNP-bound state. The structures reveal conformational changes between these states and substrate binding with or without LptC. We identify two functional transmembrane arginine-containing loops interacting with the bound AMP-PNP and elucidate allosteric communications between the domains. AMP-PNP binding induces an inward rotation and shift of the transmembrane helices of LptFG and LptC to tighten the cavity, with the closure of two lateral gates, to eventually expel LPS into the bridge. Functional assays reveal the functionality of the LptF and LptG periplasmic domains. Our findings shed light on the LPS transport mechanism

Gut microbiota and risk of lower respiratory tract infections: a bidirectional two-sample Mendelian randomization study

IntroductionObservational studies have reported the association between gut microbiota and the risk of lower respiratory tract infections (LRTIs). However, whether the association reflects a causal relationship remains obscure.MethodsA bidirectional twosample Mendelian randomization (MR) analysis was conducted by assessing genome-wide association study (GWAS) summary statistics for gut microbiota taxa and five common LRTIs. MR methods including inverse-variance-weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode were used to analyze the causality. Gene pleiotropy was tested using MR-Egger regression and MR-PRESSO methods. Cochran’s Q test was used to check for heterogeneity. Leave-one-out analysis was used to assess the stability of effect sizes. Detected significant associations were validated by using an independent LRTI GWAS summary statistics dataset. An optional MR method of causal analysis using summary effect estimates (CAUSE) was further performed as a validation to avoid potential false-positive results.ResultsAccording to the MR-Egger estimates in forward MR analysis, a causal effect of gut Blautia on increased odds of bronchiectasis and pneumonia was suggested. MR-Egger regression pleiotropy intercept methods detected no significant horizontal pleiotropy between the instrumental variables of these associations. MR-PRESSO global test examined no potential horizontal pleiotropy. Cochran’s Q test showed that no heterogeneity biased the results. The leave-one-out sensitivity analyses suggested robust causality results. These associations with consistent effect direction were successfully replicated in IVW analysis by using the validation GWAS dataset. However, these evidence of causality did not survive after applying strict Bonferroni correction or CAUSE analysis. The reverse MR analysis failed to achieve consistent results in the effect of LRTIs on gut microbiota through comprehensive discovery and validation processes.DiscussionThis study established no strong causality between genetically predicted gut microbiome and the risk of lower respiratory tract infections. However, specific subtypes of microbial genera, such as Blautia, were identified as potential influencers and require further investigation, particularly at the species or strain levels

Mitochondrial DNA in the regulation of innate immune responses

Abstract Mitochondrion is known as the energy factory of the cell, which is also a unique mammalian organelle and considered to be evolved from aerobic prokaryotes more than a billion years ago. Mitochondrial DNA, similar to that of its bacterial ancestor’s, consists of a circular loop and contains significant number of unmethylated DNA as CpG islands. The innate immune system plays an important role in the mammalian immune response. Recent research has demonstrated that mitochondrial DNA (mtDNA) activates several innate immune pathways involving TLR9, NLRP3 and STING signaling, which contributes to the signaling platforms and results in effector responses. In addition to facilitating antibacterial immunity and regulating antiviral signaling, mounting evidence suggests that mtDNA contributes to inflammatory diseases following cellular damage and stress. Therefore, in addition to its well-appreciated roles in cellular metabolism and energy production, mtDNA appears to function as a key member in the innate immune system. Here, we highlight the emerging roles of mtDNA in innate immunity

Adhesion, friction and wear analysis of a chromium oxide scale on a ferritic stainless steel

The aim of this study is to explore the potential engineering application of a thermally grown chromium oxide scale on a ferritic stainless steel. The friction and wear behaviour of the oxide scale were investigated by scratch and pin-on-disk tests. The failure mechanisms of the oxide scale subjected to scratch tests under both progressive and constant loading were investigated. It shows that the oxide scale adheres well to the steel substrate and is in a ductile failure. The oxide scale leads to an increase in the coefficient of friction (COF) under different constant loads when compared to what occurs when there is no oxide scale in the scratch test. The pin-on-disk tribological tests show that the chromium oxide scale on the ferritic stainless steel causes abrasive wear of the high-speed steel (HSS) pin, but it enhances the wear resistance of the ferritic stainless steel disk. The COF is slightly lower when there is oxide scale on the disk which is different from that by the scratch test. The ferritic steel substrate fine wear particles generated during the dry sliding and the formation of new compound layers on the surface can stabilise the COF. The wear mechanism is proposed and the tribological properties of the thermally grown chromium oxide by the two techniques are discussed