bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid Quantile Regression Estimation for Time Series Models with Conditional Heteroscedasticity
Authors: Zheng Yao , Zhu Qianqian , Li Guodong , Xiao Zhijie 
Published: June 2018

SummaryEstimating conditional quantiles of financial time series is essential for risk management and many other financial applications. For time series models with conditional heteroscedasticity, although it is the generalized auto-regressive conditional heteroscedastic (GARCH) model that has the greatest popularity, quantile regression for this model usually gives rise to non-smooth non-convex optimization which may hinder its practical feasibility. The paper proposes an easy-to-implement hybrid quantile regression estimation procedure for the GARCH model, where we overcome the intractability due to the square-root form of the conditional quantile function by a simple transformation. The method takes advantage of the efficiency of the GARCH model in modelling the volatility globally as well as the flexibility of quantile regression in fitting quantiles at a specific level. The asymptotic distribution of the estimator is derived and is approximated by a novel mixed bootstrapping procedure. A portmanteau test is further constructed to check the adequacy of fitted conditional quantiles. The finite sample performance of the method is examined by simulation studies, and its advantages over existing methods are illustrated by an empirical application to value-at-risk forecasting.
Validation of GPSkin Barrier® for assessing epidermal permeability barrier function and stratum corneum hydration in humans
Authors: Ye L. , Wang Z. , Li Z. , Lv C. , Man M.‐Q. 
Published: June 2018

AbstractBackgroundMeasurements of transepidermal water loss (TEWL) and stratum corneum (SC) hydration are important for assessing epidermal functions. However, the availability of reliable and user‐friendly devices, which can simultaneously measure both TEWL and SC hydration and can allow health providers to remotely access data in time, is limited.Materials and MethodsGPSkin Barrier® was compared with MPA5 system in the measurements of TEWL and SC hydration on the cheek, the dorsal hand, and the forearm in 200 normal volunteers, including 126 females and 74 males, aged 1‐78 years with an average age of 45.24 ± 1.04 years. Correlation of data measured with MPA5 system and GPSkin Barrier® was determined.ResultsLevels of both TEWL and SC hydration measured with the Barrie GPSkin Barrier® were lower than that with MPA5 system on all 3 body sites except for hydration on the cheek. The levels of both TEWL and SC hydration measured with GpSkin Barrier® were correlated well with that measured with MPA5 system on all 3 body sitesConclusionsGPSkin Barrier® is a reliable, affordable, and versatile device for assessing epidermal permeability barrier function and SC hydration.
Mechanical spectroscopy and imaging of skin components in vivo: Assignment of the observed moduli
Authors: Silver F. H. , Shah R. G. 
Published: June 2018

AbstractBackgroundThe need to quantitatively identify the composition and organization of the macromolecular components of skin, skin lesions, scars, tumors, extracellular matrices (ECMs), and wound tissue has been a goal of researchers for many decades. A variety of studies have been recently reported applying optical coherence tomography (OCT) to image skin and cutaneous lesions.Materials and MethodsThis article describes the use of vibrational OCT to image and noninvasively characterize the macromolecular components of the ECM of skin.ResultsWe report that the major macromolecular components of skin and scar can be identified noninvasively by their characteristic moduli calculated from measurements of the resonant frequency and tissue thickness. Moduli for fat (0.03 MPa), elastic tissue (0.8 MPa), skin (2 MPa), and scar (7 MPa) can be differentiated using images and measurements of the resonant frequency and the sample thickness obtained from OCT.ConclusionsUsing vibrational OCT, it is possible to identify and map the location of the macromolecular components in skin and skin lesions.
Donor‐derived multiorgan transmission of mixed P. malariae and P. ovale infection: Impact of globalization on post‐transplant infections
Authors: Martín‐Dávila Pilar , Norman Francesca , Fortún‐Abete Jesus , Píris Miguel , Lovatti Ruben , Rubio Jose Miguel , Martinez‐Pérez Adolfo , Graus Javier , Ta Gema , Villarubia Jesus , Mahillo Beatriz , López‐Vélez Rogelio 
Published: June 2018

AbstractA 57‐year‐old man was admitted with fever and thrombocytopenia 1 month after renal transplantation. He had never received a blood transfusion or travelled outside Spain. A peripheral blood smear revealed Plasmodium malariae and P. ovale parasites, diagnosis confirmed later by malaria PCR. The donor, from Equatorial Guinea, had negative thick and thin blood smears and rapid malaria antigen test prior to organ donation. Peripheral blood malaria PCR was not performed during donor screening. The second renal recipient and the liver recipient were evaluated and were found to be asymptomatic. Thick and thin films and rapid malaria diagnostic tests were negative for both patients and blood for malaria PCR was sent to the referral laboratory. The index patient was treated with oral chloroquine diphosphate, with a favorable outcome and was considered cured. Malaria PCR was negative for the other renal recipient and positive for P. malariae and P. ovale curtisi for the liver transplant patient. Both were treated with oral chloroquine and the liver recipient also completed treatment with primaquine phosphate. This reported case of multiorgan transmission of mixed malaria infection highlights the importance of PCR‐based tests for Plasmodium in the screening of donors from endemic areas.
VEGF‐A inhibits agonist‐mediated Ca2+ responses and activation of IKCa channels in mouse resistance artery endothelial cells
Authors: Ye Xi , Beckett Taylor , Bagher Pooneh , Garland Christopher J. , Dora Kim A. 
Published: June 2018

Key points
Prolonged exposure to vascular endothelial growth factor A (VEGF‐A) inhibits agonist‐mediated endothelial cell Ca2+ release and subsequent activation of intermediate conductance Ca2+‐activated K+ (IKCa) channels, which underpins vasodilatation as a result of endothelium‐dependent hyperpolarization (EDH) in mouse resistance arteries.
Signalling via mitogen‐activated protein/extracellular signal‐regulated kinase kinase (MEK) downstream of VEGF‐A was required to attenuate endothelial cell Ca2+ responses and the EDH‐vasodilatation mediated by IKCa activation.
VEGF‐A exposure did not modify vasodilatation as a result of the direct activation of IKCa channels, nor the pattern of expression of inositol 1,4,5‐trisphosphate receptor 1 within endothelial cells of resistance arteries.
These results indicate a novel role for VEGF‐A in resistance arteries and suggest a new avenue for investigation into the role of VEGF‐A in cardiovascular diseases.
AbstractVascular endothelial growth factor A (VEGF‐A) is a potent permeability and angiogenic factor that is also associated with the remodelling of the microvasculature. Elevated VEGF‐A levels are linked to a significant increase in the risk of cardiovascular dysfunction, although it is unclear how VEGF‐A has a detrimental, disease‐related effect. Small resistance arteries are central determinants of peripheral resistance and endothelium‐dependent hyperpolarization (EDH) is the predominant mechanism by which these arteries vasodilate. Using isolated, pressurized resistance arteries, we demonstrate that VEGF‐A acts via VEGF receptor‐2 (R2) to inhibit both endothelial cell (EC) Ca2+ release and the associated EDH vasodilatation mediated by intermediate conductance Ca2+‐activated K+ (IKCa) channels. Importantly, VEGF‐A had no direct effect against IKCa channels. Instead, the inhibition was crucially reliant on the downstream activation of the mitogen‐activated protein/extracellular signal‐regulated kinase kinase 1/2 (MEK1/2). The distribution of EC inositol 1,4,5‐trisphosphate (IP3) receptor‐1 (R1) was not affected by exposure to VEGF‐A and we propose an inhibition of IP3R1 through the MEK pathway, probably via ERK1/2. Inhibition of EC Ca2+ via VEGFR2 has profound implications for EDH‐mediated dilatation of resistance arteries and could provide a mechanism by which elevated VEGF‐A contributes towards cardiovascular dysfunction.
AupA and AupB Are Outer and Inner Membrane Proteins Involved in Alkane Uptake in Marinobacter hydrocarbonoclasticus SP17
Authors: Mounier Julie , Hakil Florence , Branchu Priscilla , Naïtali Muriel , Goulas Philippe , Sivadon Pierre , Grimaud Régis 
Published: June 2018

ABSTRACT

This study describes the functional characterization of two proteins, AupA and AupB, which are required for growth on alkanes in the marine hydrocarbonoclastic bacterium
Marinobacter hydrocarbonoclasticus
. The
aupA
and
aupB
genes form an operon whose expression was increased upon adhesion to and biofilm formation on
n-
hexadecane. AupA and AupB are outer and inner membrane proteins, respectively, which are able to interact physically. Mutations in
aupA
or/and
aupB
reduced growth on solid paraffin and liquid
n-
hexadecane, while growth on nonalkane substrates was not affected. In contrast, growth of
aup
mutants on
n-
hexadecane solubilized in Brij 58 micelles was completely abolished. Mutant cells had also lost the ability to bind to
n
-hexadecane solubilized in Brij 58 micelles. These results support the involvement of AupA and AupB in the uptake of micelle-solubilized alkanes and provide the first evidence for a cellular process involved in the micellar uptake pathway. The phylogenetic distribution of the
aupAB
operon revealed that it is widespread in marine hydrocarbonoclastic bacteria of the orders
Oceanospirillales
and
Alteromonadales
and that it is present in high copy number (up to six) in some
Alcanivorax
strains. These features suggest that Aup proteins probably confer a selective advantage in alkane-contaminated seawater.

IMPORTANCE
Bacteria are the main actors of the biological removal of hydrocarbons in seawater, and so, it is important to understand how they degrade hydrocarbons and thereby mitigate marine environmental damage. Despite a considerable amount of literature about the dynamic of microbial communities subjected to hydrocarbon exposure and the isolation of strains that degrade hydrocarbons, most of the genetic determinants and molecular mechanisms of bacterial hydrocarbon uptake remain unknown. This study identifies two genes,
aupA
and
aupB
, in the hydrocarbonoclastic bacterium
Marinobacter hydrocarbonoclasticus
that are present frequently in multiple copies in most of the marine hydrocarbon-degrading bacteria for which the genomic sequence is available. AupA and AupB are two novel membrane proteins interacting together that are involved in the uptake of alkanes dissolved in surfactant micelles. The function and the phylogenetic distribution of
aupA
and
aupB
suggest that they might be one attribute of the remarkable adaptation of marine hydrocarbonoclastic bacteria that allow them to take advantage of hydrocarbons.
Identifying and Overcoming Threats to Reproducibility, Replicability, Robustness, and Generalizability in Microbiome Research
Authors: Schloss Patrick D. 
Published: June 2018

ABSTRACT
The “reproducibility crisis” in science affects microbiology as much as any other area of inquiry, and microbiologists have long struggled to make their research reproducible. We need to respect that ensuring that our methods and results are sufficiently transparent is difficult. This difficulty is compounded in interdisciplinary fields such as microbiome research. There are many reasons why a researcher is unable to reproduce a previous result, and even if a result is reproducible, it may not be correct. Furthermore, failures to reproduce previous results have much to teach us about the scientific process and microbial life itself. This Perspective delineates a framework for identifying and overcoming threats to reproducibility, replicability, robustness, and generalizability of microbiome research. Instead of seeing signs of a crisis in others’ work, we need to appreciate the technical and social difficulties that limit reproducibility in the work of others as well as our own.
Emergence and Evolution of Novel Reassortant Influenza A Viruses in Canines in Southern China
Authors: Chen Ying , Trovão Nídia S. , Wang Guojun , Zhao Weifeng , He Ping , Zhou Huabo , Mo Yanning , Wei Zuzhang , Ouyang Kang , Huang Weijian , García-Sastre Adolfo , Nelson Martha I. 
Published: June 2018

ABSTRACT
The capacity of influenza A viruses (IAVs) to host jump from animal reservoir species to humans presents an ongoing pandemic threat. Birds and swine are considered major reservoirs of viral genetic diversity, whereas equines and canines have historically been restricted to one or two stable IAV lineages with no transmission to humans. Here, by sequencing the complete genomes of 16 IAVs obtained from canines in southern China (Guangxi Zhuang Autonomous Region [Guangxi]) in 2013 to 2015, we demonstrate that the evolution of canine influenza viruses (CIVs) in Asian dogs is increasingly complex, presenting a potential threat to humans. First, two reassortant H1N1 virus genotypes were introduced independently from swine into canines in Guangxi, including one genotype associated with a zoonotic infection. The genomes contain segments from three lineages that circulate in swine in China: North American triple reassortant H3N2, Eurasian avian-like H1N1, and pandemic H1N1. Furthermore, the swine-origin H1N1 viruses have transmitted onward in canines and reassorted with the CIV-H3N2 viruses that circulate endemically in Asian dogs, producing three novel reassortant CIV genotypes (H1N1r, H1N2r, and H3N2r [r stands for reassortant]). CIVs from this study were collected primarily from pet dogs presenting with respiratory symptoms at veterinary clinics, but dogs in Guangxi are also raised for meat, and street dogs roam freely, creating a more complex ecosystem for CIV transmission. Further surveillance is greatly needed to understand the full genetic diversity of CIV in southern China, the nature of viral emergence and persistence in the region’s diverse canine populations, and the zoonotic risk as the viruses continue to evolve.

IMPORTANCE
Mammals have emerged as critically underrecognized sources of influenza virus diversity, including pigs that were the source of the 2009 pandemic and bats and bovines that harbor highly divergent viral lineages. Here, we identify two reassortant IAVs that recently host switched from swine to canines in southern China, including one virus with known zoonotic potential. Three additional genotypes were generated via reassortment events in canine hosts, demonstrating the capacity of dogs to serve as “mixing vessels.” The continued expansion of IAV diversity in canines with high human contact rates requires enhanced surveillance and ongoing evaluation of emerging pandemic threats.
Engineering Nitrogen Fixation Activity in an Oxygenic Phototroph
Authors: Liu Deng , Liberton Michelle , Yu Jingjie , Pakrasi Himadri B. , Bhattacharyya-Pakrasi Maitrayee 
Published: June 2018

ABSTRACT

Biological nitrogen fixation is catalyzed by nitrogenase, a complex metalloenzyme found only in prokaryotes. N
2
fixation is energetically highly expensive, and an energy-generating process such as photosynthesis can meet the energy demand of N
2
fixation. However, synthesis and expression of nitrogenase are exquisitely sensitive to the presence of oxygen. Thus, engineering nitrogen fixation activity in photosynthetic organisms that produce oxygen is challenging. Cyanobacteria are oxygenic photosynthetic prokaryotes, and some of them also fix N
2
. Here, we demonstrate a feasible way to engineer nitrogenase activity in the nondiazotrophic cyanobacterium
Synechocystis
sp. PCC 6803 through the transfer of 35 nitrogen fixation (
nif
) genes from the diazotrophic cyanobacterium
Cyanothece
sp. ATCC 51142. In addition, we have identified the minimal
nif
cluster required for such activity in
Synechocystis
6803. Moreover, nitrogenase activity was significantly improved by increasing the expression levels of
nif
genes. Importantly, the O
2
tolerance of nitrogenase was enhanced by introduction of uptake hydrogenase genes, showing this to be a functional way to improve nitrogenase enzyme activity under micro-oxic conditions. To date, our efforts have resulted in engineered
Synechocystis
6803 strains that, remarkably, have more than 30% of the N
2
fixation activity of
Cyanothece
51142, the highest such activity established in any nondiazotrophic oxygenic photosynthetic organism. This report establishes a baseline for the ultimate goal of engineering nitrogen fixation ability in crop plants.

IMPORTANCE
Application of chemically synthesized nitrogen fertilizers has revolutionized agriculture. However, the energetic costs of such production processes and the widespread application of fertilizers have raised serious environmental issues. A sustainable alternative is to endow to crop plants the ability to fix atmospheric N
2
in situ
. One long-term approach is to transfer all
nif
genes from a prokaryote to plant cells and to express nitrogenase in an energy-producing organelle, chloroplast, or mitochondrion. In this context,
Synechocystis
6803, the nondiazotrophic cyanobacterium utilized in this study, provides a model chassis for rapid investigation of the necessary requirements to establish diazotrophy in an oxygenic phototroph.
Relationship of intercapillary area with visual acuity in diabetes mellitus: an optical coherence tomography angiography study
Authors: Tang Fangyao , Sun Zihan , Wong Raymond , Lok Jerry , Lam Alexander , Tham Clement C , Chan Carmen KM , Mohamed Shaheeda , Lam Thomas CH , Szeto Simon KH , Ng Danny S , Cheung Carol Y 
Published: June 2018

AimTo examine the correlation of best-corrected visual acuity (BCVA) with intercapillary area (ICA) measured from optical coherence tomography angiography (OCT-A) in patients with diabetes, and to compare the strength of associations between BCVA with ICA and other OCT-A metrics.MethodsA cross-sectional study involved 447 eyes from 299 patients with diabetes. All participants underwent OCT-A with a swept-source OCT (Triton DRI-OCT, Topcon, Tokyo, Japan). An automated customised MATLAB programme was used to quantify ICA (the mean of the 10 largest areas including foveal avascular zone (FAZ) area (ICA10_FAZ) and excluding FAZ area (ICA10_excFAZ)) and other OCT-A metrics (FAZ area, FAZ circularity and vessel density) from the macular OCT-A images. BCVA was measured using Snellen chart for the patients and then converted to logarithm of the minimum angle of resolution (logMAR) VA. We further defined ‘good VA’ as Snellen >0.7 and ‘poor VA’ as Snellen ≤0.7 as a binary VA outcome for logistic regression analysis.ResultsIn univariate regression analysis, increased ICA10_FAZ and ICA10_excFAZ were significantly correlated with logMAR (p values <0.05). In multivariate regression analysis, only the association between ICA10_FAZ and logMAR persisted (β=0.103, p=0.024). In multivariable logistic regression analysis, increased ICA10_FAZ (OR=1.300, 95% CI 1.076 to 1.679, p=0.044) and FAZ circularity (OR=1.285, 95% CI 1.031 to 1.603, p=0.026) showed significant associations with poor VA.ConclusionsIncreased ICA measured from OCT-A, describing enlargement of capillary rarefaction or closure at macular area, is independently associated with BCVA, suggesting that ICA is a potential marker to quantify retinal microvascular abnormalities relating to vision among individuals with diabetes.
Interpregnancy weight change and adverse pregnancy outcomes: a systematic review and meta-analysis
Authors: Oteng-Ntim Eugene , Mononen Sofia , Sawicki Olga , Seed Paul T , Bick Debra , Poston Lucilla 
Published: June 2018

ObjectivesTo evaluate the effect of interpregnancy body mass index (BMI) change on pregnancy outcomes, including large-for-gestational-age babies (LGA), small-for-gestational-age babies (SGA), macrosomia, gestational diabetes mellitus (GDM) and caesarean section (CS).DesignSystematic review and meta-analysis of observational cohort studies.Data sourcesLiterature searches were performed across Cochrane, MEDLINE, EMBASE, CINAHL, Global Health and MIDIRS databases.Study selectionObservational cohort studies with participants parity from 0 to 1.Main outcome measuresAdjusted ORs (aORs) with 95% CIs were used to evaluate the association between interpregnancy BMI change on five outcomes.Results925 065 women with singleton births from parity 0 to 1 were included in the meta-analysis of 11 studies selected from 924 identified studies. A substantial increase in interpregnancy BMI (>3 BMI units) was associated with an increased risk of LGA (aOR 1.85, 95% CI 1.71 to 2.00, p<0.001), GDM (aOR 2.28, 95% CI 1.97 to 2.63, p<0.001), macrosomia (aOR 1.54, 95% CI 0.939 to 2.505) and CS (aOR 1.72, 95% CI 1.32 to 2.24, p<0.001) compared with the reference category, and a decreased risk of SGA (aOR 0.83, 95% CI 0.70 to 0.99, p=0.044). An interpregnancy BMI decrease was associated with a decreased risk of LGA births (aOR 0.70, 95% CI 0.55 to 0.90, p<0.001) and GDM (aOR 0.80, 95% CI 0.62 to 1.03), and an increased risk of SGA (aOR 1.31, 95% CI 1.06 to 1.63, p=0.014). Women with a normal BMI (<25kg/m2) at first pregnancy who have a substantial increase in BMI between pregnancies had a higher risk of LGA (aOR 2.10, 95% CI 1.93 to 2.29) and GDM (aOR 3.10, 95% CI 2.74 to 3.50) when compared with a reference than women with a BMI ≥25 kg/m2at first pregnancy.ConclusionsGaining weight between pregnancies increases risk of developing GDM, CS and LGA, and reduces risk of SGA in the subsequent pregnancy. Losing weight between pregnancies reduces risk of GDM and LGA and increases risk of SGA. Weight stability between first and second pregnancy is advised in order to reduce risk of adverse outcomes.Trial registration numberCRD42016041299.