bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isothermal Titration Calorimetry: Principles and Applications
Authors: Menéndez Margarita 
Published: August 2020

Abstract

Molecular recognition is a fundamental phenomenon underpinning almost all aspects of biological processes. Associated energy changes result in release or absorption of heat that can be measured, providing valuable information about the interaction specific features. Isothermal titration calorimetry (ITC) is a label‐free binding assay which measures the affinity, stoichiometry, and thermodynamics of molecular interactions from the reaction heat. It is considered the gold‐standard technique owing to its unique capacity to provide a complete thermodynamic and even kinetic profile of the interaction in a single experiment, thus giving a detailed understanding of driving forces and underlying processes. Moreover, ITC can be used to characterise complex systems hardly amenable using other techniques and also enzyme‐catalysed reactions. Consequently, ITC is being used to study a wide range of interactions mediated by proteins, nucleic acids, lipids, oligosaccharides and other natural or synthetic molecules, and has become a key component of drug discovery platforms.

Key Concepts

Molecular recognition via noncovalent interactions is of fundamental importance to most processes occurring within living organisms.

ITC provides a general, quantitative approach to analyse the thermodynamics and kinetics of such recognition events, and to characterise enzyme‐mediated reactions.

Parsing of the free energy of binding (Δ
G
) in its two components (Δ
H
and Δ
S
) provides new insights into the molecular nature of molecular interactions being studied.

The thermodynamic signature provided by Δ
H
and Δ
S
is fundamental to not only understand naturally occurring binding interactions but is particularly useful in drug discovery studies.

The kinetics of binding events is also central to understand not only physiological processes but also drug efficacy since equilibrium states often may not be established
in vivo
.

Understanding the kinetic behaviour of enzymes is important to understand biochemical pathways and is also a yielding field for drug discovery and development, and biotechnology.
Asexual Queen Succession in Termites
Authors: Hellemans Simon , Roisin Yves 
Published: August 2020

Abstract

Termite species from phylogenetically distant lineages were shown to combine both sexual and parthenogenetic reproductions, in a breeding system dubbed as ‘asexual queen succession’. Queens of these species use sexual reproduction for the production of the workforce and dispersers, and thelytokous parthenogenesis for the production of nondispersing queens. These new queens, often produced in large numbers, will replace their mother upon her death and mate with the founding king. Replacement by these parthenogens maintains the colony's genetic diversity and enhances its growth rate, lifespan and reproductive potential. This breeding system also allows the efficient purging of recessive deleterious mutations from the genomes and contributes to shape the population sex ratio of these species. This conditional parthenogenesis evolved from a diverse cytological background, and in phylogenetically distant species with contrasted lifestyles, thereby highlighting the inherent evolutionary advantages of this strategy.

Key Concepts

The historical view of a lifelong monogamy between a primary queen and king in termites now appears obsolete.

Termite queens of some species combine the advantages of sexual and asexual reproductions in a breeding system called asexual queen succession (AQS).

AQS shapes the genomes of these species by the elimination of recessive deleterious mutations through parthenogenetically produced new queens.

AQS, along with the species' ecology and lifestyle, influences their population sex ratio.

Variations in the modalities of AQS indicate that its benefits are used in a species‐specific manner.
Glutamate as a Neurotransmitter
Authors: Lambert Peter , Mennerick Steven 
Published: August 2020

Abstract

Glutamate is an amino acid used in biochemical pathways of all cells, but it is also packaged and released as a neurotransmitter from many neurons in the vertebrate central nervous system (CNS). Glutamate is released at specific junctions, synapses, between a glutamate‐releasing neuron and target neurons that express surface receptors for glutamate. Most neurons in the vertebrate CNS, even if they themselves do not use glutamate as a neurotransmitter, have glutamate receptors. Glutamate receptors initiate electrical and biochemical signals in the target cell and can induce changes in strength of signalling that neuroscientists believe underlie the ability of thoughts and behaviours to change with experience. Glutamate receptors fall into two classes: ligand‐gated ion channels (ionotropic) and G protein coupled (metabotropic). In addition to propagating and modulating normal electrical signalling, glutamate receptors, activated excessively, can cause neurotoxicity in disease states.

Key Concepts

Glutamate is used as a neurotransmitter at the majority of synapses in the vertebrate CNS.

Glutamate typically has an excitatory action on target neurons, increasing the probability of electrical impulse firing in the target.

Glutamate acts through G protein‐coupled receptors and through ligand‐gated ion channels.

Glutamate synapses exhibit remarkable plasticity (malleability) that may play an important role in memory formation.

In excess glutamate can be neurotoxic, acting through the same glutamate receptors that mediate normal signalling.
Ephrins
Authors: Kilari Sreenivasulu , Alladi Sai Swetha , Kenche Harshavardhan 
Published: August 2020

AbstractEphrins are cell surface proteins that bind to the Eph family of receptor tyrosine kinases. Cell‐surface‐tethered ephrin‐A ligands principally activate EphA receptors, and transmembrane ephrin‐B ligands primarily activate EphB receptors. Ephs and ephrins influence many developmental processes, including compartmentalisation, cell migration, axon guidance and angiogenesis. These developmental functions arise as Ephrin–Eph interactions that shape cellular behaviours, including adhesion, migration and synaptic plasticity. Eph receptors communicate with the cytoskeleton through differential activation of small GTPases downstream of their tyrosine kinase activity. In addition to stimulating Eph receptors, ephrins signal within the cell which expresses them, a phenomenon termed ‘reverse signalling’. Ephrin‐B reverse signalling relies in part on phosphorylation of the cytoplasmic tail and recruitment of cytoplasmic proteins. Both ephrins and Ephs can modify internalisation and trafficking of other cell surface effector molecules.Cell surface receptors and ligands involved in intracellular signalling.Similar or identical molecular signals may observed in development and repair process.Primordial cells differentiate into various cell types during development.Tissue organisation and organ development from constituent cell types by compartmentalisation, cell–cell attraction and repulsion during the development.Dysregulated or abnormal cell–cell signalling lead to pathogenesis.
Who Participates in Urban Agriculture? An Empirical Analysis†
Authors: Bellemare Marc F. , Dusoruth Vaneesha 
Published: August 2020

AbstractA few highly publicized food supply chain disruptions early in the COVID‐19 pandemic were interpreted by some as evidence of a “broken” food system. One solution often brought in response to that perceived brokenness is urban agriculture. The literature, however, has sidestepped a key question: Who practices urban agriculture? Using survey data on 882 Montreal residents, we find that those who practice urban agriculture are more educated, and more likely to be homeowners and to report an income in the highest income bracket. This is consistent with urban agriculture being a luxury good.
Organic fertilizer abrasive grits increase soil available nitrogen, plant height, and biomass
Authors: Carlson Michael , Forcella Frank , Wortman Sam , Clay David , Clay Sharon A. 
Published: August 2020

AbstractIn organic cropping systems, air‐propelled abrasive grits can be used to control in‐row weeds. If the applied abrasive grit is an approved organic fertilizer, these applications may serve a dual purpose of weed control and crop fertility. Laboratory soil incubations examined the N mineralization rates of several grit types with differing C/N ratios (Agra Grit [crushed walnut shells, 170:1], corncob grit [91:1], Sustane [composted turkey litter, 5.0:1], Phytaboost Plant Food [crushed and pelletized soybean meal, 5.0:1]). A greenhouse study determined plant wheat (Triticum aestivum L.), kale (Brassica napus pabluaria DC), and velvetleaf (Abutilon theophrasti Medik.) growth response in soils amended with these grits. The N mineralization rates varied by grit type, soil, and application rate. The N mineralized from Phytaboost within 56 d was similar among the amounts of N a whereas the amount of N mineralized from Sustane was inversely related to the amount of N applied. Agra Grit and corncob grit immobilized soil N due to their high C/N ratios. In soils amended with Sustane, plant height and biomass were 15–43% and 34–83% greater than for plants grown in soils with Agra Grit, corncob grit, and the nontreated soil. Applications of organic fertilizer as air‐propelled grit may improve crop growth; however, if weed control is imperfect, these grits may increase weed growth. Grits with high C/N ratios may immobilize soil available N but not affect plant growth.
Effect of different factors on plant regeneration from leaf explants of Jatropha curcas L.
Authors: Liu Ying , Chen Jingye , Li Xiaohao , Xue Yingbin 
Published: August 2020

AbstractThe in vitro regeneration frequency was commonly low, and the quality of adventitious buds was poor, when the traditional methods were used to induce adventitious buds from leaf explants of Jatropha curcas L. through the medium containing low concentration of thidiazuron (TDZ). When treated with high concentrations (6.5–104 mg/L) of TDZ for a certain time (7–120 min), the regeneration frequency and quality of adventitious buds were significantly increased. The best induction rate of adventitious buds (78.58%) and the average number of buds per explant (7.26) were obtained by soaking leaf explants in 26 mg/L TDZ solution for 30 min and then transferring them onto MS medium without hormone for 30 days. Furthermore, the adventitious bud regeneration was affected obviously by source of explants, sterilization time, illumination time and genotype. The subsequent elongation and rooting experiments showed that adventitious bud elongation could be improved by adding diethyl aminoethyl hexanoate (DA‐6) in the medium, and the best elongation effect could be gained when the concentration of DA‐6 was 1.2 mg/L. The elongated shoots induced the roots and developed into small intact plants on the MS medium with 1.5 mg/L sodium nitroprusside (SNP). After domestication, these small plants could be transplanted into the soil and growing normally. Therefore, the method established in this study was helpful to improve the plant regeneration efficiency of leaf explants in J. curcas.
Comparison of the perioperative outcomes of laparoscopic surgery, robotic surgery, open surgery, and transanal total mesorectal excision for rectal cancer: An overview of systematic reviews
Authors: Yamamoto Seiichiro 
Published: August 2020

AbstractRegarding the surgical approaches for rectal cancer, many techniques have been reported in randomized controlled trials, meta‐analyses, and reviews of comparisons between two techniques, e.g. open surgery vs laparoscopic surgery, laparoscopic surgery vs robotic surgery, or laparoscopic surgery vs transanal total mesorectal excision. Since robotic surgery and transanal total mesorectal excision were developed after laparoscopic surgery had become an established minimally invasive technique, they have each been compared with laparoscopic surgery. Therefore, a review was performed to compare the surgical outcomes of robotic surgery and transanal total mesorectal excision, and to perform such comparisons among ≥3 of the above mentioned approaches, in the expectation that this review will serve as a reference for aiding treatment selection in future. The results of the current review suggest that all of the examined procedures have advantages and disadvantages, but that there are no decisive factors that could be used to select one procedure over any other. At the present time it cannot be demonstrated that laparoscopic surgery, robotic surgery, transanal total mesorectal excision, or open surgery is superior to the other techniques, and it is important to select the best technique for each patient from among those that a surgeon can perform. It is also important to maintain a flexible attitude that allows new techniques to be adopted as needed in the future.
A computational study of water in UiO‐66 Zr‐MOFs: Diffusion, hydrogen bonding network, and confinement effect
Authors: Wang Shanshan , Zhou Guobing , Sun Yunhao , Huang Liangliang 
Published: August 2020

AbstractFor chemical warfare agent removal, the humidity emerges as an unavoidable challenge that significantly affects the performance of metal–organic frameworks. In this work, via density functional theory calculations, ab initio molecular dynamics and classical molecular dynamics simulations, we investigate the structural and diffusion properties of water in the pristine defect‐free UiO‐66, one Zr‐based metal–organic framework. Through the detailed analyses of the distribution probability of water in two different cages of UiO‐66, the binding interaction between water and UiO‐66, the hydrogen bonding networks and resulted localized water clusters, we gain a fundamental understanding of structural and dynamics properties as well as the concentration dependence of water in UiO‐66. We anticipate those theoretical results could provide insight to the competitive adsorption of water and chemical warfare agents, which eventually shows the utmost importance for the design and development of the next generation porous materials with appropriate water properties in real‐life applications.
Construction of Highly Active Metal‐Containing Nanoparticles and FeCo‐N4 Composite Sites for the Acidic Oxygen Reduction Reaction
Authors: Yin Shu‐Hu , Yang Jian , Han Yu , Li Gen , Wan Li‐Yang , Chen You‐Hu , Chen Chi , Qu Xi‐Ming , Jiang Yan‐Xia , Sun Shi‐Gang 
Published: August 2020

AbstractMetal‐containing nanoparticles (M‐NPs) in metal/nitrogen‐doped carbon (M‐N‐C) catalysts have been considered hostile to the acidic oxygen reduction reaction (ORR). The relation between M‐NPs and the active sites of metal coordinated with nitrogen (MNx) is hard to establish in acid medium owing to the poor stability of M‐NPs. Herein, we develop a strategy to successfully construct a new FeCo‐N‐C catalyst containing highly active M‐NPs and MN4 composite sites (M/FeCo‐SAs‐N‐C). Enhanced catalytic activity and stability of M/FeCo‐SAs‐N‐C is shown experimentally. Calculations reveal that there is a strong interaction between M‐NPs and FeN4 sites, which can favor ORR by activating the O−O bond, thus facilitating a direct 4 e− process. Those findings firstly shed light on the highly active M‐NPs and FeN4 composite sites for catalyzing acid oxygen reduction reaction, and the relevant reaction mechanism is suggested.
An Unusual Type II Polyketide Synthase System Involved in Cinnamoyl Lipid Biosynthesis
Authors: Deng Zirong , Liu Jing , Li Tong , Li Huayue , Liu Zengzhi , Dong Yujing , Li Wenli 
Published: August 2020

AbstractAs a unique structural moiety in natural products, cinnamoyl lipids (CLs), are proposed to be assembled by unusual type II polyketide synthases (PKSs). Herein, we demonstrate that the assembly of the CL compounds youssoufenes is accomplished by a PKS system that uniquely harbors three phylogenetically different ketosynthase/chain length factor (KS/CLF) complexes (YsfB/C, YsfD/E, and YsfJ/K). Through in vivo gene inactivation and in vitro reconstitution, as well as an intracellular tagged carrier‐protein tracking (ITCT) strategy developed in this study, we successfully elucidated the isomerase‐dependent ACP‐tethered polyunsaturated chain elongation process. The three KS/CLFs were revealed to modularly assemble different parts of the youssoufene skeleton, during which benzene ring closure happens right after the formation of an ACP‐tethered C18 polyene. Of note, the ITCT strategy could significantly contribute to the elucidation of other carrier‐protein‐dependent biosynthetic machineries.
Dry Fractionation of Cupuassu (Theobroma grandiflorum) Fat: Physical–Chemical Properties and Polymorphic Behavior
Authors: Rodríguez‐Negrette Ana Carolina , Rodríguez‐Batiller María José , García‐Londoño Victor Alonso , Borroni Virginia , Candal Roberto Jorge , Herrera María Lidia 
Published: September 2020

AbstractPhysical chemical properties of cupuassu fat were modified by dry fractionation. Stearin and olein fractions were obtained at 29, 26, and 24 °C. Polymorphic behavior of unfractionated cupuassu fat (UCF) and its fractions were studied in situ by small‐angle (SAXS) and wide‐angle (WAXS) X‐ray scattering using synchrotron light. Polymorphic transitions were followed in real time tempering samples with a thermal cycle. For UCF, the main polymorphic form crystallized under selected conditions was the β’2. α and β’1‐forms appeared in trace amounts. β2‐form was obtained after storage at 25 °C for 3 months. Stearins obtained at 26 (S‐26) and 24 °C (S‐24) showed a similar polymorphic behavior. However, S‐26 with improved physical properties might be more suitable for chocolate production or as a trans‐fat alternative than UCF. Stearin fraction obtained at 29 °C (S‐29) had a complex polymorphic behavior. The α‐form was the first polymorphic form detected followed by β’2‐form. There was a polymorphic transition from α to β’1‐form but no transition between β’‐forms. They were independent to each other showing fractionation in two different solid solutions. Increased contents of the triacylglycerols (TAG) SOA and SOB together with lower contents of SOO compared to UCF led to co‐crystallization because there was no complete compatibility among all TAG present in S‐29. β1‐form crystallized after storage forming crystals with a double‐layer arrangement and a characteristic morphology. This form could be useful for accelerating crystallization process in melted liquid systems.
Sex Differences in Salience Network Connectivity and its Relationship to Sensory Over‐Responsivity in Youth with Autism Spectrum Disorder
Authors: Cummings Kaitlin K. , Lawrence Katherine E. , Hernandez Leanna M. , Wood Emily T. , Bookheimer Susan Y. , Dapretto Mirella , Green Shulamite A. 
Published: August 2020

AbstractIndividuals with autism spectrum disorder (ASD) are significantly more likely to experience sensory over‐responsivity (SOR) compared to neurotypical controls. SOR in autism has been shown to be related to atypical functional connectivity in the salience network (SN), a brain network thought to help direct attention to the most relevant stimuli in one's environment. However, all studies to date which have examined the neurobiological basis of sensory processing in ASD have used primarily male samples so little is known about sex differences in the neural processing of sensory information. This study examined the relationship between SOR and resting‐state functional connectivity in the SN for 37 males and 16 females with autism, ages 8–17 years. While there were no sex differences in parent‐rated SOR symptoms, there were significant sex differences in how SOR related to SN connectivity. Relative to females with ASD, males with ASD showed a stronger association between SOR and increased connectivity between the salience and primary sensory networks, suggesting increased allocation to sensory information. Conversely, for females with ASD, SOR was more strongly related to increased connectivity between the SN and prefrontal cortex. Results suggest that the underlying mechanisms of SOR in ASD are sex specific, providing insight into the differences seen in the diagnosis rate and symptom profiles of males and females with ASD.Lay SummarySensory over‐responsivity (SOR) is common in autism. Most research on the neural basis of SOR has focused on males, so little is known about SOR or its neurobiology in females with autism spectrum disorder. Here despite no sex differences in SOR symptoms, we found sex differences in how SOR related to intrinsic connectivity in a salience detection network. Results show sex differences in the neural mechanisms underlying SOR and inform sex differences seen in diagnosis rates and symptom profiles in autism. Autism Res 2020, 13: 1489–1500. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.
Surgical resection of symptomatic brain metastases improves the clinical status and facilitates further treatment
Authors: Schödel Petra , Jünger Stephanie T. , Wittersheim Maike , Reinhardt Hans Christian , Schmidt Nils‐Ole , Goldbrunner Roland , Proescholdt Martin , Grau Stefan 
Published: August 2020

AbstractBackgroundBrain metastases (BM) frequently cause focal neurological deficits leading to a reduced Karnofsky performance score (KPS). Since KPS is routinely used to guide the choice of adjuvant therapy, we hypothesized that improving KPS by surgical resection may improve the chance for adjuvant treatment and ultimately result in better survival. We therefore analyzed the course of a large cohort undergoing resection of symptomatic brain metastases in the context of further treatment and clinical outcome.Patients and methodsIn a bi‐centric retrospective analysis we retrieved baseline, clinical, and treatment‐related parameters of patients operated on BM between 2010 and 2019. Survival was calculated using Kaplan‐Meier estimates; prognostic factors for survival were analyzed by Log‐rank test and Cox proportional hazards.ResultsWe included 750 patients with a median age of 61 (19‐87) years. The functional status was significantly improved by surgical resection, with a median preoperative (KPS) of 80 (10‐100) increasing to 90 (0‐100) after surgery (P < .0001). Moreover, surgery improved the RTOG recursive partitioning analysis (RPA) class from III to I/II in 82 patients. Postoperative local radiotherapy and systemic treatment were associated with significantly longer survival (P < .0001 for each). Systemic treatment was provided significantly more frequently in patients with a fair postoperative clinical status (KPS ≥ 70; P < .0001). The postoperative clinical status, postoperative radiotherapy, systemic treatment, controlled systemic disease and < 4 BM were independent predictors for survival.ConclusionThe resection of symptomatic BM may restore clinical status, so enhancing the likelihood of receiving adjuvant treatment, and therefore leading to improved overall survival.