bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cognitive reserve in a sample of Cuban older adults with Mild Cognitive Impairment
Authors: Jiménez-Puig Elizabeth , Baute-Abreu Ana Cristina , Valdés-Pérez Daniela Liz , Santana-Domínguez Yeisel , Añón-Villegas Marina Jesús , Pérez-Leiva Brayan Deivi 
Published: August 2021

AbstractIntroductionAging is a natural process that occurs in all individuals. Due to the increase in aging figures worldwide, the diagnosis of mild cognitive impairment and other dementia syndromes has increased. An element of essential relevance in protecting against the risk of suffering from dementia is the cognitive reserve.ObjectiveTo indicate the levels of cognitive reserve in a sample of Cuban older adults with Mild Cognitive Impairment.MethodsAn exploratory study was carried out using questionnaires, with a cross-sectional, quantitative design. The sampling was non-probabilistic and intentional, obtaining a sample of 51 older adults with mild cognitive impairment. The information collection was carried out from the Cognitive Reserve Scale (CRS). Quantitative data was analyzed through frequency analysis.ResultsMost of the participants showed higher levels of cognitive reserve for carrying out activities of daily life and for relating to other people. The dimensions most affected were Formation / Information and Hobbies.ConclusionsThe research allowed a preliminary approach to the cognitive reserve of older adults. It would be interesting to conduct investigations of this nature in larger samples, including groups of healthy controls, which would allow comparison of results. In addition, it would be relevant to investigate the impact of institutionalization.
Development of an efficient single-cell cloning and expansion strategy for genome edited induced pluripotent stem cells
Authors: Bhargava Nupur , Thakur Priya , Muruganandam Thulasi Priyadharshini , Jaitly Shashank , Gupta Pragya , Lohani Neelam , Goswami Sangam Giri , Bhattacharya Saurabh Kumar , Jain Suman , Ramalingam Sivaprakash 
Published: August 2021

AbstractDisease-specific human induced pluripotent stem cells (hiPSCs) can be generated directly from individuals with known disease characteristics or alternatively be modified using genome editing approaches to introduce disease causing genetic mutations to study the biological response of those mutations. The genome editing procedure in hiPSCs is still inefficient, particularly when it comes to homology directed repair (HDR) of genetic mutations or targeted transgene insertion in the genome and single cell cloning of edited cells. In addition, genome editing processes also involve additional cellular stresses such as trouble with cell viability and genetic stability of hiPSCs. Therefore, efficient workflows are desired to increase genome editing application to hiPSC disease models and therapeutic applications. Apart from genome editing efficiency, hiPSC survival following single-cell cloning has proved to be challenging and has thus restricted the capability to easily isolate homogeneous clones from edited hiPSCs. To this end, we demonstrate an efficient workflow for feeder-free single cell clone generation and expansion in both CRISPR-mediated knock-out (KO) and knock-in (KI) hiPSC lines. Using StemFlex medium and CloneR supplement in conjunction with Matrigel cell culture matrix, we show that cell viability and expansion during single-cell cloning in edited and unedited cells is significantly enhanced. Our reliable single-cell cloning and expansion workflow did not affect the biology of the hiPSCs as the cells retained their growth and morphology, expression of various pluripotency markers and normal karyotype. This simplified and efficient workflow will allow for a new level of sophistication in generating hiPSC-based disease models to promote rapid advancement in basic research and also the development of novel cellular therapeutics.
Histone H1 prevents non-CG methylation-mediated small RNA biogenesis in Arabidopsis heterochromatin
Authors: Choi Jaemyung , Lyons David B. , Zilberman Daniel 
Published: August 2021

AbstractFlowering plants utilize small RNA molecules to guide DNA methyltransferases to genomic sequences. This RNA-directed DNA methylation (RdDM) pathway preferentially targets euchromatic transposable elements. However, RdDM is thought to be recruited by methylation of histone H3 at lysine 9 (H3K9me), a hallmark of heterochromatin. How RdDM is targeted to euchromatin despite an affinity for H3K9me is unclear. Here we show that loss of histone H1 enhances heterochromatic RdDM, preferentially at nucleosome linker DNA. Surprisingly, this does not require SHH1, the RdDM component that binds H3K9me. Furthermore, H3K9me is dispensable for RdDM, as is CG DNA methylation. Instead, we find that non-CG methylation is specifically required for small RNA biogenesis, and without H1 small RNA production quantitatively expands to non-CG methylated loci. Our results demonstrate that H1 enforces the separation of euchromatic and heterochromatic DNA methylation pathways by excluding the small RNA-generating branch of RdDM from non-CG methylated heterochromatin.
A pore-forming protein drives macropinocytosis to facilitate toad water maintaining
Authors: Zhao Zhong , Shi Zhi-Hong , Ye Chen-Jun , Zhang Yun 
Published: August 2021

AbstractMaintaining water balance is a real challenge for amphibians in terrestrial environments. Our previous studies with toad Bombina maxima discovered a secretory aerolysin family pore-forming protein and trefoil factor complex βγ-CAT, which is assembled under tight regulation depending on environmental cues. Here we report an unexpected role for βγ-CAT in toad water maintaining. Deletion of toad skin secretions, in which βγ-CAT is a major component, increased animal mortality under hypertonic stress. βγ-CAT was constitutively expressed in toad osmoregulatory organs, which was inducible under the variation of osmotic conditions. The protein induced and participated in macropinocytosis in vivo and in vitro. During extracellular hyperosmosis, βγ-CAT stimulated macropinocytosis to facilitate water intake and enhanced exosomes release, which simultaneously regulated aquaporins distribution. Collectively, these findings uncovered that besides membrane integrated aquaporins, a secretory pore-forming protein can facilitate toad water maintaining via macropinocytosis induction and exocytosis modulation, especially in responses to osmotic stress.
The immediate early protein 1 of human herpesvirus 6B counteracts ATM activation in an NBS1-dependent manner
Authors: Collin Vanessa , Biquand Élise , Tremblay Vincent , Lavoie Élise G. , Dessapt Julien , Blondeau Andréanne , Gravel Annie , Flamand Louis , Fradet-Turcotte Amélie 
Published: August 2021

AbstractViral infection often trigger an ATM-dependent DNA damage response (DDR) in host cells that suppresses viral replication. To counteract this antiviral surveillance system, viruses evolved different strategies to induce the degradation of the MRE11/RAD50/NBS1 (MRN) complex and prevent subsequent DDR signaling. Here, we report that human herpesvirus 6B (HHV-6B) infection causes genomic instability by suppressing the host cell’s ability to induce ATM-dependent signaling pathways. Expression of immediate early protein 1 (IE1) phenocopies this phenotype and blocks further homology-directed double-strand break (DSB) repair. In contrast to other viruses, IE1 does not affect the stability of the MRN complex. Instead, it uses two distinct domains to inhibit ATM serine/threonine kinase (ATM) activation at DSBs. Structure-based analyses revealed that the N-terminal domain of IE1 interacts with the BRCA1 C-terminal domain 2 of nibrin (NBN, also known as NBS1), while ATM inhibition is attributable to on its C-terminal domain. Consistent with the role of the MRN complex in antiviral responses, NBS1 depletion resulted in increased HHV-6B replication in infected cells. However, in semi-permissive cells, viral integration of HHV-6B into the telomeres was not strictly dependent on NBS1, supporting models where this process occurs via telomere elongation rather than through DNA repair. Interestingly, as IE1 expression has been detected in cells of subjects with inherited chromosomally-integrated form of HHV-6B (iciHHV-6B), a condition associated with several health conditions, our results raise the possibility of a link between genomic instability and the development of iciHHV-6-associated diseases.Significance StatementMany viruses have evolved ways to inhibit DNA damage signaling, presumably to prevent infected cells from activating an antiviral response. Here, we show that this is also true for human herpesvirus 6B (HHV-6B), through its immediate early protein 1 (IE1). However, in contrast to adenovirus’ immediate early proteins, HHV-6B IE1 is recruited to double-strand breaks in an NBS1-dependent manner and inhibits ATM serine/threonine kinase activation. Characterizing this phenotype revealed a unique mechanism by which HHV-6B manipulates DNA damage signaling in infected cells. Consistently, viral replication is restricted by the MRN complex in HHV-6B infected cells. Viral integration of HHV-6B into the host’s telomeres is not strictly dependent on NBS1, challenging current models where integration occurs through homology-directed repair.
Unloxing the assembly and activation mechanism of Cre recombinase using Cryo-EM
Authors: Stachowski Kye , Norris Andrew , Potter Devante , Wysocki Vicki , Foster Mark P. 
Published: August 2021

AbstractMechanistic understanding of the structural basis for DNA recombination in the Cre-loxP system has largely been guided by crystallographic structures of tetrameric synaptic complexes (intasomes). These structural and biochemical studies have suggested that conformational changes and DNA bending in presynaptic complexes underlie site-selection and activation mechanisms of Cre recombinase. Here we used protein engineering and various DNA substrates to isolate the Cre-loxP (54 kDa), Cre2-loxP (110 kDa), and Cre4-loxP2 assembly intermediates, and determined their structures using cryo-EM to resolutions of 3.9 Å, 4.5 Å, and 3.2 Å, respectively. Progressive DNA bending along the assembly pathway enables formation of increasingly intimate protein-protein interfaces. Insufficient stabilization of important protein motifs observed during the assembly process provides a compelling explanation for the observed half-the-sites activity, and preferential bottom strand cleavage of loxP sequences. We found that selection of loxP sites is largely dependent on Cre’s ability to bend and stabilize the spacer region between two recombinase binding elements. Application of 3D variability analysis to the tetramer data reveals a propensity for motion along the pathway between protomer activation and Holliday junction isomerization. These findings help us to better understand loxP site specificity, controlled activation of alternating protomers, the basis for the observed bias of strand cleavage order, and the importance of conformational sampling, especially with regards to site-selection and activity among Cre variants. Furthermore, our findings provide invaluable information for the rational development of designer, site-specific recombinases for use as gene editing technologies.HighlightsCryo-EM structures of Cre-loxP assembly intermediates (monomer, dimer, and tetramer) provide insights into mechanisms of site recognition, half-the-sites activity, strand cleavage order, and concerted strand cleavageSelectivity of loxP sites arises from few base-specific contacts made by each protomer and is mainly driven by formation of phosphate contacts and DNA deformations that are maximal in the fully assembled “active” tetramerCis and trans interactions of the β2-3 loop (i) define which sites are “active” and (ii) ensure half-the-sites activityProtein flexibility plays a central role in enabling DNA sequence scanning, recruitment of a second protein to form a dimer, synapsis, control of activity, as well as subsequent recombination stepsConformational sampling within the tetrameric complex was uncovered using 3D variability analysis and revealed the importance of protein-protein interfaces for site- selection and activation of Cre-loxP complexes
fHow ATP and dATP act as molecular switches to regulate enzymatic activity in the prototypic bacterial class Ia ribonucleotide reductase
Authors: Funk Michael A. , Zimanyi Christina M. , Andree Gisele A. , Hamilos Allison E. , Drennan Catherine L. 
Published: August 2021

AbstractClass Ia ribonucleotide reductases (RNRs) are subject to allosteric regulation to maintain the appropriate deoxyribonucleotide levels for accurate DNA biosynthesis and repair. RNR activity requires a precise alignment of its α2 and β2 subunits such that a catalytically-essential radical species is transferred from β2 to α2. In E. coli, when too many deoxyribonucleotides are produced, dATP binding to RNR generates an inactive α4β4 state in which β2 and α2 are separated, preventing radical transfer. ATP binding breaks the α−β interface, freeing β2 and restoring activity. Here we investigate the molecular basis for allosteric activity regulation in the prototypic E. coli class Ia RNR. Through the determination of six crystal structures we are able to establish how dATP binding creates a binding pocket for β on α that traps β2 in the inactive α4β4 state. These structural snapshots also reveal the numerous ATP-induced conformational rearrangements that are responsible for freeing β2. We further discover, and validate through binding and mutagenesis studies, a previously unknown nucleotide binding site on the α subunit that is crucial for the ability of ATP to dismantle the inactive α4β4 state. These findings have implications for the design of allosteric inhibitors for bacterial RNRs.
‘I don’t feel like I’m learning how to be a doctor’: early insights regarding the impact of Covid-19 on UK medical student professional identity
Authors: Harvey Anna , Brown Megan E L , Byrne Matthew H V , Alexander Laith , Wan Jonathan C M , Ashcroft James , Schindler Nicholas , Brassett Cecilia 
Published: August 2021

AbstractPhenomenonProfessional identity development is recognised as a core goal of medical education alongside knowledge and skill acquisition. Identity is a complex entity that can be conceptualised as externally influenced, but individually constructed. Integration from legitimate bystander to ‘old timer’ of the medical community of practice provides a backdrop for individual negotiation of professional identity. During Covid-19, the medical community of practice and education experienced significant disruption. We sought to investigate how these disruptions impacted professional identity development by examining conflicts between students’ identities highlighted by the pressures of the pandemic.ApproachA mixed-methods survey was distributed to medical students in the UK. The survey was active from 2nd May to 15th June 2020, during the height of the first wave of the Covid-19 pandemic in the UK. Operating within the paradigm of constructivism, we conducted a reflexive thematic analysis of qualitative responses. Analysis was focused around the disruption to medical education, actions taken by medical students during this disruption, and the tension between student actions where they existed in conflict.FindingsThree themes were constructed to describe the identities that participants felt were in conflict during the first wave of the Covid-19 pandemic: Status and role as a future doctor; status and role as a student; and status and role as a member of the wider community. Students noted that lack of clinical exposure was detrimental to their education, implicitly recognising that many aspects of professional identity formation are forged in the clinical environment. Participants were keen to volunteer clinically but struggled to balance this with academic work. Participants worried about the risk to their families and the wider community, and wanted to ensure that their skills would add value to the clinical environment. Volunteers felt frustrated when they were unable to perform tasks which aligned with their identities as future doctors, with the exception of participants who worked as interim FY1s (FiY1s), which aligned well with the roles of FY1s.InsightsAs hypothesised, the participants in this study experienced disruptions to their professional identity development during the first wave of the Covid-19 pandemic in 2020. This work provides early evidence, collected at the beginning of the pandemic, that the effects of disruptions to professional identity development were wide-reaching, often negative, and represent an important topic for future exploration. Given that the pandemic has highlighted areas of identity tension, these findings have the potential to provide insight into how medical training can better nurture professional identity development during and beyond international crises.
Disturbance rejection control of airborne radar stabilized platform based on active disturbance rejection control inverse estimation algorithm
Authors: Mei Dong , Yu Zhu-Qing 
Published: August 2021

Purpose
This paper aims to study a disturbance rejection controller to improve the anti-interference capability and the position tracking performance of airborne radar stabilized platform that ensures the stability and clarity of synthetic aperture radar imaging.

Design/methodology/approach
This study proposes a disturbance rejection control scheme for an airborne radar stabilized platform based on the active disturbance rejection control (ADRC) inverse estimation algorithm. Exploiting the extended state observer (ESO) characteristic, an inversely ESO is developed to inverse estimate the unmodeled state and extended state of the platform system known as total disturbances, which greatly improves the estimation performance of the disturbance. Then, based on the inverse ESO result, feedback the difference between the output of the tracking differentiator and the inverse ESO result to the nonlinear state error feedback controller (NLSEF) to eliminate the effects of total disturbance and ensure the stability of the airborne radar stabilized platform.

Findings
Simulation experiments are adopted to compare the performance of the ADRC inverse estimation algorithm with that of the proportional integral derivative controller which is one of the mostly applied control schemes in platform systems. In addition, classical ADRC is compared as well. The results have shown that the ADRC inverse estimation algorithm has a better disturbance rejection performance when disturbance acts in airborne radar stabilized platform, especially disturbed by continuous airflow under some harsh air conditions.

Originality/value
The originality of this paper is exploiting the ESO characteristic to develop an inverse ESO, which greatly improves the estimation performance of the disturbance. And the ADRC inverse estimation algorithm is applied to ameliorate the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous interference under complex air conditions.
Minimizing deviations of car sequencing in a JIT production painting line
Authors: Denizhan Berrin , Özçelik Salih , Havuç Tuğba 
Published: August 2021

Purpose
The first in first out (FIFO) rule is an indispensable rule in the automotive industry. However, during production, the order of coming to welding operation and exiting through the painting operation is broken. Consequently, the rule of FIFO also gets broken. The purpose of this paper is to eliminate the deviations of the automotive painting process in a just in time (JIT) environment.

Design/methodology/approach
The paper has been solved using observations and expert’s opinions and recorded data in the real problem area. Bypass technique and express line have been used as a real problem for the minimization of these deviations. The current process and the bypass process have been compared with simulation optimization.

Findings
This paper provides analytical insights about how to prevent delays during the JIT production painting process. Delays have been prevented by using the bypass technique and express line together. The number of delays reduced with an improvement of 129. The ratio of effect (for four months) has been founded to be 0.12. The output rate has been increased from 80% to 89%.

Research limitations/implications
This paper focused on the number of vehicles in the cooling area of the painting process in the study; there may occur bottleneck processes or products. It does not contain station-based bottleneck processes.

Practical implications
From the real-case problem, one will see that the bypass technique and the express line can be applied and generalized to many similar problems and help companies conduct their assembly lines more efficiently.

Originality/value
This paper is the only example that has been used to bypass technique and express line together on the paint/cooling process in a JIT production system.
Integrating critical chain project management with last planner system for linear scheduling of modular construction
Authors: Salama Tarek , Salah Ahmad , Moselhi Osama 
Published: August 2021

Purpose
The purpose of this paper is to present a new method for project tracking and control of integrated offsite and onsite activities in modular construction considering practical characteristics associated with this type of construction.

Design/methodology/approach
The design embraces building information modelling and integrates last planner system (LPS), linear scheduling method (LSM) and critical chain project management (CCPM) to develop tracking and control procedures for modular construction projects. The developed method accounts for constraints of resources continuity and uncertainties associated with activity duration. Features of proposed method are illustrated in a case example for tracking and control of modular projects.

Findings
Comparison between developed schedule and Monte Carlo simulation showed that baseline duration generated from simulation exceeds that produced by developed method by 12% and 10% for schedules with 50% and 90% confidence level, respectively. These percentages decrease based on interventions of members of project team in the LPS sessions. The case example results indicate that project is delayed 5% and experienced cost overrun of 2.5%.

Originality/value
Developed method integrated LPS, LSM and CCPM while using metrics for reliability assessment of linear schedules, namely, critical percent plan complete (PPCcr) and buffer index (BI). PPCcr and BI measure percentage of plan completion for critical activities and buffer consumption, respectively. The developed method provides a systematic procedure for forecasting look-ahead schedules using forecasting correction factor Δt and a newly developed tracking and control procedure that uses PPCcr and BI. Quantitative cost analysis is also provided to forecast and monitor project costs to prove the robustness of proposed framework.