bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Characterization of the Solution Kinetics and Thermodynamics of Biotin, Biocytin and HABA Binding to Avidin and Streptavidin
Authors: Delgadillo Roberto F. , Mueser Timothy C. , Zaleta-Rivera Kathia , Carnes Katie A. , González-Valdez José , Parkhurst Lawrence J. 
Published: September 2018

ABSTRACTThe high affinity (KD∼ 10−15M) of biotin to avidin and streptavidin is the essential component in a multitude of bioassays with many experiments using biotin modifications to invoke coupling. Equilibration times suggested for these assays assume that the association rate constant (kon) is approximately diffusion limited (109M−1s−1) but recent single molecule and surface binding studies indicate they are slower than expected (105to 107M−1s−1). In this study, we asked whether these reactions in solution are diffusion controlled, what reaction model and thermodynamic cycle described the complex formation, and the functional differences between avidin and streptavidin. We have studied the biotin association by two stopped-flow methodologies using labeled and unlabeled probes: I) fluorescent probes attached to biotin and biocytin; and II) unlabeled biotin and HABA, 2-(4’-hydroxyazobenzene)-benzoic acid. Native avidin and streptavidin are homo-tetrameric and the association data show no cooperativity between the binding sites. The konvalues of streptavidin are faster than avidin but slower than expected for a diffusion limited reaction in both complexes. Moreover, the Arrhenius plots of the konvalues revealed strong temperature dependence with large activation energies (6-15 kcal/mol) that do not correspond to a diffusion limited process (3-4 kcal/mol). The data suggest that the avidin binding sites are deeper and less accessible than those of streptavidin. Accordingly, we propose a simple reaction model with a single transition state for non-immobilized reactants whose forward thermodynamic parameters complete the thermodynamic cycle in agreement with previously reported studies. Our new understanding and description of the kinetics, thermodynamics and spectroscopic parameters for these complexes will help to improve purification efficiencies, molecule detection, and drug screening assays or find new applications.
Control of eNOS and nNOS through regulation of obligatory conformational changes in the reductase catalytic cycle
Authors: Salerno John C. , Hopper Benjamin L. , Ghosh Dipak. K. , Scott Israel M. , McMurry Jonathan L. 
Published: September 2018

AbstractEndothelial and neuronal nitric oxide synthases (eNOS, nNOS) are important signal generators in a number of processes including angiogenesis and neurotransmission. The homologous inducible isoform (iNOS) occupies a multitude of conformational states in a catalytic cycle, including subnanosecond input and output states and a distribution of ‘open’ conformations with average lifetimes of ~4.3 ns. In this study, fluorescence lifetime spectroscopy was used to probe conformational states of purified eNOS and nNOS in the presence of chaotropes, calmodulin, NADP+ and NADPH. Two-domain FMN/oxygenase constructs of nNOS were also examined with respect to calmodulin effects. Optical biosensing was used to analyze calmodulin binding in the presence of NADP+ and NADPH. Calmodulin binding induced a shift of the population away from the input and to the open and output states of NOS. NADP+ shifted the population towards the input state. The oxygenase domain, lacking the input state, provided a measure of calmodulin-induced open-output transitions. A mechanism for regulation by calmodulin and an elucidation of the catalytic mechanism are suggested by a ‘conformational lockdown’ model. Calmodulin speeds transitions between input and open and between open and output states, effectively reducing the conformational manifold, speeding catalysis. Conformational control of catalysis involves reorientation of the FMN binding domain, of which fluorescence lifetime is an indicator. The approach described herein is a new tool for biophysical and structural analysis of NOS enzymes, regulatory events and other homologous reductase-containing enzymes.A note to the readerThis manuscript has over the past several years been submitted to and rejected by several journals, usually on the basis of reviewer opinion that it was not an important enough result to merit inclusion in the journal. Owing to the passing of the first author and the loss of his expertise in fluorescence lifetime spectroscopy, it has become too onerous a task to continually revise the manuscript to suit the whims of reviewers who nevertheless still reject the work. We are thus simply releasing the final form of the manuscript to BioRxiv in the hopes that it finds a readership who will find, as we do, that the results are of value to the field.
Fall Risk Prediction in Multiple Sclerosis Using Postural Sway Measures: A Machine Learning Approach
Authors: Sun Ruopeng , Hsieh Katherine L. , Sosnoff Jacob J. 
Published: September 2018

AbstractBackgroundBalance impairment affects over 75% of individuals with multiple sclerosis (MS), and leads to an increased risk of falling. Numerous postural sway metrics have been shown to be sensitive to balance impairment and fall risk in individuals with MS. Yet, there are no guidelines concerning the most appropriate postural sway metrics to monitor impairment. This investigation implemented a machine learning approach to assess the accuracy and feature importance of various postural sway metrics to differentiate individuals with MS from healthy controls as a function of physiological fall risk.MethodsThis secondary data analysis included 153 participants (50 controls and 103 individuals with MS) who underwent posturography based balance assessment (30s eyes open standing on a force platform) and physiological fall risk assessment (Physiological Profile Assessment - PPA). Participants were further classified into four subgroups based on fall risk: controls (n=50, 64.9 ± 4.9 years old, PPA < 1); low-risk MS (n=34, 54.0 ± 13.1 years old, PPA < 1); moderate-risk MS (n=27, 58.3 ± 8.3 years old, 1 ≤ PPA < 2); high-risk MS (n=42, 56.8 ± 9.7 years old, PPA ≥ 2). Twenty common sway metrics were derived following standard procedures, and subsequently used to train a machine learning algorithm (random forest – RF, with 10-fold cross validation) to predict individuals’ fall risk grouping. The feature importance from the RF algorithms was used to select the strongest sway metric for fall risk prediction.Results and DiscussionThe sway-metric based RF classifier had high classification accuracy in discriminating controls from MS individuals (> 86%). Sway sample entropy, a sway regularity metric, was identified as the strongest feature for classification of low-risk MS individuals from healthy controls. Whereas for all other comparisons, mediolateral sway amplitude was identified as the strongest predictor for fall risk groupings. These findings may set the foundation for the development of guidelines for reporting balance impairment in individuals with MS.
Active site closure stabilizes the backtracked state of RNA polymerase
Authors: Turtola Matti , Mäkinen Janne J. , Belogurov Georgiy A. 
Published: September 2018

ABSTRACTAll cellular RNA polymerases (RNAP) occasionally backtrack along the template DNA as part of transcriptional proofreading and regulation. Here, we studied the mechanism of RNAP backtracking by one nucleotide using two complementary approaches that allowed us to precisely measure the occupancy and lifetime of the backtracked state. Our data show that the stability of the backtracked state is critically dependent on the closure of the RNAP active site by a mobile domain, the trigger loop (TL). The lifetime and occupancy of the backtracked state measurably decreased by substitutions of the TL residues that interact with the nucleoside triphosphate (NTP) substrate, whereas amino acid substitutions that stabilized the closed active site increased the lifetime and occupancy. These results suggest that the same conformer of the TL closes the active site during catalysis of nucleotide incorporation into the nascent RNA and backtracking by one nucleotide. In support of this hypothesis, we construct a model of the 1-nt backtracked complex with the closed active site and the backtracked nucleotide in the entry pore area known as the E-site. We further propose that 1-nt backtracking mimics the reversal of the NTP substrate loading into the RNAP active site during on-pathway elongation.
The effects of awareness of the perturbation during motor adaptation on hand localization
Authors: Modchalingam Shanaathanan , Vachon Chad Michael , ’t Hart Bernard Marius , Henriques Denise Y. P. 
Published: September 2018

ABSTRACTExplicit awareness of a task is often evoked during rehabilitation and sports training with the intention of accelerating learning and improving performance. However, the effects of awareness of perturbations on the resulting sensory and motor changes produced during motor learning are not well understood. Here, we use explicit instructions as well as large rotation sizes to generate awareness of the perturbation during a visuomotor rotation task and test the resulting changes in both perceived and predicted sensory consequences as well as implicit motor changes.We split participants into 4 groups which differ in both magnitude of the rotation (either 30° or 60°) during adaptation, and whether they receive a strategy to counter the rotation or not prior to adaptation. Performance benefits of explicit instruction are largest during early adaptation but continued to lead to improved performance through 90 trials of training. We show that with either instruction, or with large perturbations, participants become aware of countering the rotation. However, we find a base amount of implicit learning, with equal magnitudes, across all groups, even when asked to exclude any strategies while reaching with no visual feedback of the hand.Participants also estimate the location of the unseen hand when it is moved by the robot (passive localization) and when they generate their own movement (active localization) following adaptation. These learning-induced shifts in estimates of hand position reflect both proprioceptive recalibration and updates in the predicted consequences of movements. We find that these estimates of felt hand position, which reflect updates in both proprioception and efference based estimates of hand position, shift significantly for all groups and were not modulated by either instruction or perturbation size.Our results indicate that not all processes of motor learning benefit from an explicit awareness of the task. Particularly, proprioceptive recalibration and the updating of predicted sensory consequences are largely implicit processes.
Dimerisation of APOBEC1 is dispensable for its RNA/DNA editing activity and modulates its availability
Authors: Chieca Martina , Montini Marco , Severi Francesco , Lembo Gaia , Donati Francesco , Pecori Riccardo , Conticello Silvestro G. 
Published: September 2018

ABSTRACTThe AID/APOBECs are DNA/RNA deaminases whose mutagenic activity has been linked to cancer. Among them, APOBEC1 physiologically partakes into a complex that edits a CAA codon into UAA Stop codon in the transcript of Apolipoprotein B (APOB), a protein crucial in the transport of lipids in the blood. Catalytically inactive mutants of APOBEC1 have a dominant negative effect on its activity, as they compete for the targeting of the APOB mRNA. Here we titrate APOBEC1-mediated editing in presence of catalytically inactive chimeras and mutants of APOBEC1, and we show that APOBEC1 inability to dimerise is the main determinant for its activity. This property is especially evident in an APOBEC1 mutant (L173A G227A) with increased activity on RNA despite decreased self-interaction. Moreover, dimerisation protects APOBEC1 from degradation and regulates its availability. Considering APOBEC1 capability to target DNA, we demonstrate that increased availability of the protein due to dimerisation leads to increase in the DNA damage induced by APOBEC1. These findings demonstrate that dimerisation, a property common to other APOBECs targeting DNA, might represent another layer in the regulation of this editing enzyme.BULLET POINTSAPOBEC1 inability to dimerise is the main determinant for its activity.Dimerisation protects APOBEC1 from degradation and regulates its availability.Alterations in the balance between monomeric and dimeric APOBEC1 increase DNA damage.
Serotonin regulates dynamics of cerebellar granule cell activity by modulating tonic inhibition
Authors: Fleming Elizabeth , Hull Court 
Published: September 2018

AbstractUnderstanding how afferent information is integrated by cortical structures requires identifying the factors shaping excitation and inhibition within their input layers. The input layer of the cerebellar cortex integrates diverse sensorimotor information to enable learned associations that refine the dynamics of movement. Specifically, mossy fiber afferents relay sensorimotor input into the cerebellum to excite granule cells, whose activity is regulated by inhibitory Golgi cells. To test how this integration can be modulated, we have used an acute brain slice preparation from young adult rats and found that encoding of mossy fiber input in the cerebellar granule cell layer can be regulated by serotonin (5-HT) via a specific action on Golgi cells. We find that 5-HT depolarizes Golgi cells, likely by activating 5-HT2A receptors, but does not directly act on either granule cells or mossy fibers. As a result of Golgi cell depolarization, 5-HT significantly increases tonic inhibition onto both granule cells and Golgi cells. 5-HT-mediated Golgi cell depolarization is not sufficient, however, to alter the probability or timing of mossy fiber-evoked feed-forward inhibition onto granule cells. Together, increased granule cell tonic inhibition paired with normal feed-forward inhibition acts to reduce granule cell spike probability without altering spike timing. These data hence provide a circuit mechanism by which 5-HT can reduce granule cell activity without altering temporal representations of mossy fiber input. Such changes in network integration could enable flexible, state-specific suppression of cerebellar sensorimotor input that should not be learned, or enable reversal learning for unwanted associations.New and Noteworthy5-HT regulates synaptic integration at the input stage of cerebellar processing by increasing tonic inhibition of granule cells. This circuit mechanism reduces the probability of granule cell spiking without altering spike timing, thus suppressing cerebellar input without altering its temporal representation in the granule cell layer.
The performance implications of the UNE 166.000 standardised innovation management system
Authors: Martínez-Costa Micaela , Jimenez-Jimenez Daniel , Castro-del-Rosario Yolanda del Pilar 
Published: September 2018

PurposeThe purpose of this paper is to analyse the effects of implementing a standardised innovation management system (SIMS) in accordance with the Spanish UNE 166.000 standard on technological and administrative innovations and company performance.Design/methodology/approachStructural equation modelling was used to test the research hypotheses with a sample of 200 manufacturing companies.FindingsThe results obtained show that implementing the SIMS promotes all types of innovations and their results. In addition, a positive relationship is found between administrative and technological innovation.Research limitations/implicationsThe results of this paper show the importance of innovation management systems for the effective development of innovation processes. Despite the limitations that may arise from differences between the measurements and actual implementation, the application of a system of standard-based innovation management encourages the development of different types of innovation.Practical implicationsThe research validates the use of standardisation for the development of innovation as a useful tool for the management of innovation in the company. The UNE 166.000 standard provides a guide for those companies that intend to develop more effectively administrative and technological innovations.Originality/valueThis is the first known paper testing the implications of UNE 166.000 SIMS on both organisational innovation and performance in a sample of companies.
The image attributes of a destination: an analysis of the wine tourists’ perception
Authors: Scorrano Paola , Fait Monica , Iaia Lea , Rosato Pierfelice 
Published: September 2018

PurposeThe purpose of this paper is to identify the features that qualify the wine tourism destinations’ (WTDs) image and to deepen analyse the role of the image on the wine tourists’ perception, assuming that it changes from tourist to tourist, depending on who has formed its perception after a real experience or not.Design/methodology/approachThis contribution fits in the range of studies regarding the measurement of the destination image; the authors suited the Echtner and Ritchie’s model (1991, 1993), as its multidimensionality approach, rarely applied in the area of wine tourism.FindingsFrom a comparison between the images of the chosen destination, wine tourists consider Bordeaux the benchmark of WTDs and, in the collective imagery, France is one of the excellences between WTDs. The association territory-wine is less marked, so the biggest contribute is given by thein situexperience.Research limitations/implicationsDespite results can’t be generalised because the samples of convenience, they have provided an overall outline of attributes, benefits and attitudes of wine tourists of Web 2.0.Practical implicationsA managerial lecture of results shows that young destinations (aka new wine regions) have a bigger propensity for destination management as well as the attention to marketing aspects, which are able to influence the competitiveness of destination. Instead, destinations with an ancient tradition (aka old wine regions), although unique for their wines and territories, food traditions and the historic-architectural heritage, need to improve their services.Originality/valueThis research applies the consolidated analysis method of E&R on the theme of destination image to the wine tourism, never used for WTDs, improving the model with a comparison between visitor and no-visitor perceptions.
Sustainability ratings in residential development: a worthwhile endeavour?
Authors: Warren-Myers Georgia , Judge Madeline , Paladino Angela 
Published: September 2018

Purpose
Rating tools for the built environment were designed to engage consumers and enhance sustainability and resilience. However, the intended outcomes of these rating systems appear to have limited implementation in the residential new housing market in Australia. The purpose of this paper is to investigate consumers’ motivations and experiences who have purchased houses that are situated in a sustainability-based certified development and will have been required to comply with mandatory dwelling certification.

Design/methodology/approach
The paper explores the awareness and perception of sustainability ratings and whether the motivations for purchasing in the sustainably certified development have heightened their awareness of sustainability and the resilience of new housing. This has been investigated through a pilot study of consumers who have purchased land in a certified estate and built a new home, through an online survey.

Findings
The findings reveal that the rating systems are at present not having the desired influence as first thought; that is, to inform consumers of the sustainability of a dwelling or property and to instigate trust of the environmental credentials of the property.

Research limitations/implications
This illuminating case study of participants who have purchased a sustainable rated development demonstrates that regardless of their concern for environmental issues, consumers have both low awareness and trust in the ratings. Despite this, consumers do seek value from these credentials to the overall property.

Originality/value
This study aims to illustrate the disconnect in engagement between developers, builders and new home buyers in relation to sustainability certification and implementation.
Comparing and contrasting the evolution through time of organizational sustainability initiatives
Authors: Rodriguez Rocio , Svensson Göran , Eriksson David 
Published: September 2018

Purpose
The purpose of this study is to compare private and public hospitals’ sustainability actions, as well as to contrast their organizational evolution over time (i.e. past, present and expected future) in the Spanish health-care sector. Sustainability initiatives refer to organizations’ economic, social and environmental actions.

Design/methodology/approach
This study applies an inductive approach based on judgmental sampling and in-depth interviews of key informants at private and public hospitals in the Spanish health-care sector. Data were gathered from the executive in charge of corporate social responsibility in public hospitals and the directors of communication at private hospitals.

Findings
Although the private and public hospitals studied are in the same health-care industry and run similar operations, their organizational sustainability initiatives in the past, present and expected future differ. The scope of sustainability initiatives between private and public hospitals is different, compared through time. Who was and who is promoting, as well as who is going to promote sustainability initiatives, also differs between private and public hospitals.

Research limitations/implications
One limitation of this study is that it was undertaken exclusively in Spanish organizations from one industry, but this is also a benefit, as it enables a comparison and contrast of the evolution between private and public hospitals. Future research could focus on the evolution of organizational sustainability initiatives in other industries and countries.

Practical implications
The reported comparison of empirical findings between private and public hospitals, as well as the subsequent discussion contrasting these findings, yields various managerial implications in terms of the scope and promotor of sustainable actions.

Originality/value
This study differs from previous ones by exploring the evolutionary details of the organizational sustainability initiatives through time in both private and public hospitals. This study also makes a contribution by revealing common denominators and differentiators between private and public hospitals that operate in the same health-care industry.