bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical Conditions of Fast Glacier Flow: 3. Seasonally‐Evolving Ice Deformation on Store Glacier, West Greenland
Authors: Young T. J. , Christoffersen P. , Doyle S. H. , Nicholls K. W. , Stewart C. L. , Hubbard B. , Hubbard A. , Lok L. B. , Brennan P. V. , Benn D. I. , Luckman A. , Bougamont M. 
Published: January 2019

Temporal variations in ice sheet flow directly impact the internal structure within ice sheets through englacial deformation. Large‐scale changes in the vertical stratigraphy within ice sheets have been previously conducted on centennial to millennial timescales; however, intra‐annual changes in the morphology of internal layers have yet to be explored. Over a period of 2 years, we use autonomous phase‐sensitive radio‐echo sounding to track the daily displacement of internal layers on Store Glacier, West Greenland, to millimeter accuracy. At a site located ∼30 km from the calving terminus, where the ice is ∼600 m thick and flows at ∼700 m/a, we measure distinct seasonal variations in vertical velocities and vertical strain rates over a 2‐year period. Prior to the melt season (March–June), we observe increasingly nonlinear englacial deformation with negative vertical strain rates (i.e., strain thinning) in the upper half of the ice column of approximately −0.03 a−1, whereas the ice below thickens under vertical strain reaching up to +0.16 a−1. Early in the melt season (June–July), vertical thinning gradually ceases as the glacier increasingly thickens. During late summer to midwinter (August–February), vertical thickening occurs linearly throughout the entire ice column, with strain rates averaging 0.016 a−1. We show that these complex variations are unrelated to topographic setting and localized basal slip and hypothesize that this seasonality is driven by far‐field perturbations in the glacier's force balance, in this case generated by variations in basal hydrology near the glacier's terminus and propagated tens of kilometers upstream through transient basal lubrication longitudinal coupling.
Comment on “Derivation of a Sigmoid Generalized Complementary Function for Evaporation With Physical Constraints” by S. Han and F. Tian
Authors: Szilagyi Jozsef , Crago Richard D. 
Published: January 2019

AbstractThe sigmoid function Han and Tian derive for their E/Ep = f (Er/Ep) complementary relationship leads to physical contradictions, therefore cannot be accepted as an improvement of existing complementary relationship theory.
Predicting long-term corrosion of metal alloys in physical infrastructure
Authors: Melchers Robert E. 
Published: January 2019

AbstractThe conditions for initiation and the subsequent development of the severity of corrosion of metal alloys in the short term continue to be of research interest. However, for most physical infrastructure the critical issue often is the development and progression of corrosion under some level of oxygenated conditions, over several decades. In many cases this has significant implications for safety and for economic loss. Increasingly, asset management decision-making requires robust tools or models to predict the effect of corrosion, including loss, pit depth and crevice severity. The present capability in this area is reviewed and available models generally compared, including their degree of empiricism and their relationship to corrosion science fundamentals. It is argued that in addition to the role of material imperfections and corrosion products, the immediate physical environment adjacent to the metal alloy also can play a major role. These aspects are explored and some speculation made about required future research directions.
The Tri-phasic Role of Hydrogen Peroxide in Blood-Brain Barrier Endothelial cells
Authors: Anasooya Shaji Chinchusha , Robinson Bobby D. , Yeager Antonia , Beeram Madhava R. , Davis Matthew L. , Isbell Claire L. , Huang Jason H. , Tharakan Binu 
Published: January 2019

AbstractHydrogen peroxide (H2O2) plays an important role physiologically as the second messenger and pathologically as an inducer of oxidative stress in injury, ischemia and other conditions. However, it is unclear how H2O2 influences various cellular functions in health and disease differentially, particularly in the blood-brain barrier (BBB). We hypothesized that the change in cellular concentrations of H2O2 is a major contributor in regulation of angiogenesis, barrier integrity/permeability and cell death/apoptosis in BBB endothelial cells. Rat brain microvascular endothelial cells were exposed to various concentrations of H2O2 (1 nM to 25 mM). BBB tight junction protein (zonula ocludens-1; ZO-1) localization and expression, cytoskeletal organization, monolayer permeability, angiogenesis, cell viability and apoptosis were evaluated. H2O2 at low concentrations (0.001 μM to 1 μM) increased endothelial cell tube formation indicating enhanced angiogenesis. H2O2 at 100 μM and above induced monolayer hyperpermeability significantly (p < 0.05). H2O2 at 10 mM and above decreased cell viability and induced apoptosis (p < 0.05). There was a decrease of ZO-1 tight junction localization with 100 μm H2O2, but had no effect on protein expression. Cytoskeletal disorganizations were observed starting at 1 μm. In conclusion H2O2 influences angiogenesis, permeability, and cell death/apoptosis in a tri-phasic and concentration-dependent manner in microvascular endothelial cells of the blood-brain barrier.
Endothelin-converting enzyme-1 regulates glucagon-like peptide-1 receptor signalling and resensitisation
Authors: Lu Jing , Willars Gary B. 
Published: January 2019

AbstractFollowing nutrient ingestion, glucagon-like peptide 1 (GLP-1) is secreted from intestinal L-cells and mediates anti-diabetic effects, most notably stimulating glucose-dependent insulin release from pancreatic β-cells but also inhibiting glucagon release, promoting satiety and weight reduction and potentially enhancing or preserving β-cell mass. These effects are mediated by the GLP-1 receptor (GLP-1R), which is a therapeutic target in type 2 diabetes. Although agonism at the GLP-1R has been well studied, desensitisation and resensitisation are perhaps less well explored. An understanding of these events is important, particularly in the design and use of novel receptor ligands. Here, using either HEK293 cells expressing the recombinant human GLP-1R or the pancreatic β-cell line, INS-1E with endogenous expressesion of the GLP-1R, we demonstrate GLP-1R desensitisation and subsequent resensitisation following removal of extracellular GLP-1 7-36 amide. Resensitisation is dependent on receptor internalisation, endosomal acidification and receptor recycling. Resensitisation is also regulated by endothelin-converting enzyme-1 (ECE-1) activity, most likely through proteolysis of GLP-1 in endosomes and the facilitation of GLP-1R dephosphorylation and recycling. Inhibition of ECE-1 activity also increases GLP-1-induced activation of extracellular signal-regulated kinase and generation of cAMP, suggesting processes dependent upon the lifetime of the internalised ligand–receptor complex.
The morphology and histology study on rabbit degenerated medial meniscus after posterior cruciate ligament rupture
Authors: Deng Zhenhan , Luo Wei , Gao Shanshan , Liao Zhan , Hu Yihe , He Hongbo , Zhang Can , Li Kanghua 
Published: January 2019

Abstract
The morphology and histology changes in the medial meniscus after posterior cruciate ligament (PCL) rupture are poorly understood. Forty-eight rabbits were divided into matched mode pairs; each rabbit had an experimental side, in which the PCL was transacted, and a control side. At the 4, 8, 16 and 24 weeks after the PCL transection, each of the 12 rabbits was killed. Histology was performed to detect the expression of the tissue inhibitors of metalloproteinases-1 (TIMP-1), matrix metalloproteinase (MMP)-1 and MMP-13 in the medial meniscus. We found that medial meniscus displayed significant degenerative characteristics in morphology. The histological evaluation of the degeneration found that the expression levels of TIMP-1, MMP-1 and MMP-13 in the medial meniscus were higher in the experiment side than those in the control side (P&lt;0.05). The expression of both TIMP-1 and MMP-13 was initially elevated and then decreased. The MMP-1 expression reached its peak swiftly and then maintained a relatively high level. There were clear time-dependent degenerative changes in the histology of the medial meniscus after PCL rupture. The high expression of TIMP-1, MMP-1 and MMP-13 in the cartilage may be responsible for the degeneration, and PCL rupture may trigger meniscus degradation and ultimately osteoarthritis.
Learning the ABCs one at a time: structure and mechanism of ABC transporters
Authors: Ford Robert C. , Beis Konstantinos 
Published: January 2019

Abstract
ATP-binding cassette (ABC) transporters are essential proteins that are found across all kingdoms of life. ABC transporters harness the energy of ATP hydrolysis to drive the import of nutrients inside bacterial cells or the export of toxic compounds or essential lipids across bacteria and eukaryotic membranes. Typically, ABC transporters consist of transmembrane domains (TMDs) and nucleotide-binding domains (NBDs) to bind their substrate and ATP, respectively. The TMDs dictate what ligands can be recognised, whereas the NBDs are the power engine of the ABC transporter, carrying out ATP binding and hydrolysis. It has been proposed that they utilise the alternating access mechanism, inward- to outward-facing conformation, to transport their substrates. Here, we will review the recent progress on the structure determination of eukaryotic and bacterial ABC transporters as well as the novel mechanisms that have also been proposed, that fall out of the alternating access mechanism model.
The role of metal ions in the virulence and viability of bacterial pathogens
Authors: Begg Stephanie L. 
Published: January 2019

Abstract
Metal ions fulfil a plethora of essential roles within bacterial pathogens. In addition to acting as necessary cofactors for cellular proteins, making them indispensable for both protein structure and function, they also fulfil roles in signalling and regulation of virulence. Consequently, the maintenance of cellular metal ion homeostasis is crucial for bacterial viability and pathogenicity. It is therefore unsurprising that components of the immune response target and exploit both the essentiality of metal ions and their potential toxicity toward invading bacteria. This review provides a brief overview of the transition metal ions iron, manganese, copper and zinc during infection. These essential metal ions are discussed in the context of host modulation of bioavailability, bacterial acquisition and efflux, metal-regulated virulence factor expression and the molecular mechanisms that contribute to loss of viability and/or virulence during host-imposed metal stress.
Breast tumour organoids: promising models for the genomic and functional characterisation of breast cancer
Authors: Roelofs Charlotte , Hollande Frédéric , Redvers Richard , Anderson Robin L. , Merino Delphine 
Published: January 2019

Abstract
Until recently, established cancer cell lines have been used extensively in breast cancer research, due largely to the difficulties associated with the manipulation and long-term maintenance in culture of primary tumour cells from patients. The recent development of organoid cultures has provided new opportunities to model and analyse patient samples, allowing the propagation of malignant cells under conditions that resemble the three-dimensional growth of breast tumours. They have proved efficacious in preserving the heterogeneity of primary samples and are emerging as a new model to further characterise the molecular features of breast cancer. Organoids formed from patient-derived cells are now in use for the evaluation of drug sensitivity and to validate disease-causing genomic variations. Here, the advantages and limitations of organoid cultures will be discussed and compared with the parallel development of other two- and three-dimensional culture strategies and with patient-derived xenografts. In particular, we will focus on the molecular characterisation of breast cancer organoids and provide some examples of how they have been used in functional studies.
Keeping the balance in NAD metabolism
Authors: Strømland Øyvind , Niere Marc , Nikiforov Andrey A. , VanLinden Magali R. , Heiland Ines , Ziegler Mathias 
Published: January 2019

Abstract
Research over the last few decades has extended our understanding of nicotinamide adenine dinucleotide (NAD) from a vital redox carrier to an important signalling molecule that is involved in the regulation of a multitude of fundamental cellular processes. This includes DNA repair, cell cycle regulation, gene expression and calcium signalling, in which NAD is a substrate for several families of regulatory proteins, such as sirtuins and ADP-ribosyltransferases. At the molecular level, NAD-dependent signalling events differ from hydride transfer by cleavage of the dinucleotide into an ADP-ribosyl moiety and nicotinamide. Therefore, non-redox functions of NAD require continuous biosynthesis of the dinucleotide. Maintenance of cellular NAD levels is mainly achieved by nicotinamide salvage, yet a variety of other precursors can be used to sustain cellular NAD levels via different biosynthetic routes. Biosynthesis and consumption of NAD are compartmentalised at the subcellular level, and currently little is known about the generation and role of some of these subcellular NAD pools. Impaired biosynthesis or increased NAD consumption is deleterious and associated with ageing and several pathologies. Insults to neurons lead to depletion of axonal NAD and rapid degeneration, partial rescue can be achieved pharmacologically by administration of specific NAD precursors. Restoring NAD levels by stimulating biosynthesis or through supplementation with precursors also produces beneficial therapeutic effects in several disease models. In this review, we will briefly discuss the most recent achievements and the challenges ahead in this diverse research field.
Multilayered control of chromosome replication in Caulobacter crescentus
Authors: Frandi Antonio , Collier Justine 
Published: January 2019

Abstract
The environmental Alphaproteobacterium Caulobacter crescentus is a classical model to study the regulation of the bacterial cell cycle. It divides asymmetrically, giving a stalked cell that immediately enters S phase and a swarmer cell that stays in the G1 phase until it differentiates into a stalked cell. Its genome consists in a single circular chromosome whose replication is tightly regulated so that it happens only in stalked cells and only once per cell cycle. Imbalances in chromosomal copy numbers are the most often highly deleterious, if not lethal. This review highlights recent discoveries on pathways that control chromosome replication when Caulobacter is exposed to optimal or less optimal growth conditions. Most of these pathways target two proteins that bind directly onto the chromosomal origin: the highly conserved DnaA initiator of DNA replication and the CtrA response regulator that is found in most Alphaproteobacteria. The concerted inactivation and proteolysis of CtrA during the swarmer-to-stalked cell transition license cells to enter S phase, while a replisome-associated Regulated Inactivation and proteolysis of DnaA (RIDA) process ensures that initiation starts only once per cell cycle. When Caulobacter is stressed, it turns on control systems that delay the G1-to-S phase transition or the elongation of DNA replication, most probably increasing its fitness and adaptation capacities.
Inferring physical parameters in solar prominence threads
Authors: Montes-Solís M. , Arregui I. 
Published: January 2019

Context. High resolution observations have permitted the resolution of solar prominences/filaments into sets of threads/fibrils. However, the values of the physical parameters of these threads and their structuring remain poorly constrained.
Aims. We use prominence seismology techniques to analyse transverse oscillations in threads by comparing magnetohydrodynamic (MHD) models and observations.
Methods. We applied Bayesian methods to obtain two different types of information. We first inferred the marginal posterior distribution of physical parameters such as the magnetic field strength or length of the thread, when a totally filled tube, partially filled tube, and three damping models are considered as certain; the three damping models are resonant absorption in the Alfvén continuum, resonant absorption in the slow continuum, and Cowling’s diffusion. Then, we compared the relative plausibility between alternative MHD models by computing the Bayes factors.
Results. Well-constrained probability density distributions can be obtained for the magnetic field strength, length of the thread, density contrast, and parameters associated with the damping models. In a comparison of the damping models of resonant absorption in the Alfvén continuum, resonant absorption in the slow continuum, and Cowling’s diffusion due to partial ionisation of prominence plasma, the resonant absorption in the Alfvén continuum is the most plausible mechanism to explain the existing observations. Relations between periods of fundamental and first overtone kink modes with values around 1 are better explained by expressions of the period ratio in the long thread approximation, while the rest of the values are more probable in the short thread limit for the period ratio.
Conclusions. Our results show that Bayesian analysis offers valuable methods to perform parameter inference and a model comparison in the context of prominence seismology.
H2/HD molecular data for analysis of quasar spectra in search of varying constants
Authors: Ubachs W. , Salumbides E. J. , Murphy M. T. , Abgrall H. , Roueff E. 
Published: January 2019

Context. Absorption lines of H2 and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio μ. For this purpose, results from astronomical observations are compared with a compilation of molecular data of the highest accuracy, obtained in laboratory studies as well as in first-principles calculations.
Aims. A comprehensive line list is compiled for H2 and HD absorption lines in the Lyman (B1Σu+ − X1Σg+) and Werner (C1Πu − X1Σg+) band systems up to the Lyman cutoff at 912 Å. Molecular parameters listed for each line i are the transition wavelength λi, the line oscillator strength fi, the radiative damping parameter of the excited state Γi, and the sensitivity coefficient Ki for a variation of the proton-to-electron mass ratio.
Methods. The transition wavelengths λi for the H2 and HD molecules are determined by a variety of advanced high-precision spectroscopic experiments involving narrowband vacuum ultraviolet lasers, Fourier-transform spectrometers, and synchrotron radiation sources. Results for the line oscillator strengths fi, damping parameters Γi, and sensitivity coefficients Ki are obtained in theoretical quantum chemical calculations.
Results. A new list of molecular data is compiled for future analyses of cold clouds of hydrogen absorbers, specifically for studies of μ-variation from quasar data. The list is applied in a refit of quasar absorption spectra of B0642–5038 and J1237+0647 yielding constraints on a variation of the proton-to-electron mass ratio Δμ/μ consistent with previous analyses.
Screening and development of enzymes for determination and transformation of amino acids
Authors: Asano Yasuhisa 
Published: January 2019

ABSTRACT
The high stereo- and substrate specificities of enzymes have been utilized for micro-determination of amino acids. Here, I review the discovery of l-Phe dehydrogenase and its practical use in the diagnosis of phenylketonuria in more than 5,400,000 neonates over two decades in Japan. Screening and uses of other selective enzymes for micro-determination of amino acids have also been discussed. In addition, novel enzymatic assays with the systematic use of known enzymes, including assays based on a pyrophosphate detection system using pyrophosphate dikinase for a variety of l-amino acids with amino-acyl-tRNA synthetase have been reviewed. Finally, I review the substrate specificities of a few amino acid-metabolizing enzymes that have been altered, using protein engineering techniques, mainly for production of useful chemicals, thus enabling the wider use of natural enzymes.
Elucidation of an α-glucosidase inhibitor from the peel of Allium cepa by principal component analysis
Authors: Ogi Kayako , Sumitani Hidenobu 
Published: January 2019

ABSTRACT
We conducted liquid chromatography-mass spectrometry measurements on hot-water extracts of peel from different varieties of Allium cepa. Some quercetin glycosides were identified as potential α-glucosidase inhibitors by principal component analysis of the liquid chromatography-mass spectrometry data. α-Glucosidase inhibitory activity assays identified quercetin-4ʹ-O-glucoside as an α-glucosidase inhibitor.
Bone quality in young adults with intellectual disability involved in adapted competitive football
Authors: Lizondo Vicente , Caplliure‐Llopis Jordi , Escrivá Dolores , De La Rubia Jose Enrique , Barrios Carlos 
Published: January 2019

ABSTRACTThe objective of this study was to analyse bone quality parameters of football players with intellectual disability (ID) participating in adapted competitive football. Sixty‐seven male football players with ID were studied: 22 with Down syndrome (DS) and 45 without DS. The average age was 26 years (range: 16 ̶ 50 years). A group of 25 age‐matched sedentary individuals with ID (11 DS and 14 non‐DS) and another group of 20 healthy participants of the same age group not involved in competitive football were comparatively analysed. There were no differences in the bone quality parameters when the healthy sedentary individuals were compared with both the sedentary and the football players with ID. However, the speed of sound (SOS), T‐score, and estimated bone mineral density (BMD) were of higher values in the football players with ID than in the sedentary ID group (p < 0.05). On comparing the football players with non‐DS ID with the sedentary non‐DS individuals, significant differences were noted in SOS (p < 0.01), T‐scores (p < 0.01), and estimated BMD (p < 0.01). Four of the 45 non‐DS (8.9%) and none of the football players with DS had T‐scores less than −1.5. Two of the 14 sedentary non‐DS participants (14.3%) had T‐scores indicating osteoporosis. In summary, the ID population actively involved in football showed higher values of bone mass parameters than their sedentary ID and healthy peers. The participants with non‐DS ID showed a higher prevalence of osteoporosis than the football players with DS. Participation in sports seems to prevent bone loss in individuals with ID.