Enzymatic degradation of liquid droplets of DNA is modulated near the phase boundary.

Biomolecules can undergo liquid-liquid phase separation (LLPS), forming dense droplets that are increasingly understood to be important for cellular function. Analogous systems are studied as early-life compartmentalization mechanisms, for applications as protocells, or as drug-delivery vehicles. In many of these situations, interactions between the droplet and enzymatic solutes are important to achieve certain functions. To explore this, we carried out experiments in which a model LLPS system, formed from DNA "nanostar" particles, interacted with a DNA-cleaving restriction enzyme, SmaI, whose activity degraded the droplets, causing them to shrink with time. By controlling adhesion of the DNA droplet to a glass surface, we were able to carry out time-resolved imaging of this "active dissolution" process. We found that the scaling properties of droplet shrinking were sensitive to the proximity to the dissolution ("boiling") temperature of the dense liquid: For systems far from the boiling point, enzymes acted only on the droplet surface, while systems poised near the boiling point permitted enzyme penetration. This was corroborated by the observation of enzyme-induced vacuole-formation ("bubbling") events, which can only occur through enzyme internalization, and which occurred only in systems poised near the boiling point. Overall, our results demonstrate a mechanism through which the phase stability of a liquid affects its enzymatic degradation through modulation of enzyme transport properties.

Length-Dependence and Spatial Structure of DNA Partitioning into a DNA Liquid.

Cells can spatially and temporally control biochemistry using liquid-liquid phase separation to form membrane-less organelles. Synthetic biomolecular liquids offer a means to study the mechanisms of this process, as well as offering a route to the creation of functional biomimetic materials. With these goals in mind, we here examine the partitioning of long double-stranded DNA linkers into a liquid composed of small DNA particles ("nanostars") whose phase separation is driven by base pairing. We find that linker partitioning is length-dependent because of a confinement penalty of inserting long strands within the liquid's characteristic mesh size. We quantify this entropic-confinement effect using a simple partitioning theory and show that its magnitude is consistent with classic Odijk pictures of confined worm-like chains. Linker partitioning can also lead to inhomogeneous structures: long linkers excluded from the liquid interior tend to preferentially accumulate on the surface of liquid droplets (i.e., acting as surfactants), while linkers forced at high concentrations into the liquid undergo a secondary phase separation, forming metastable droplet-in-droplet structures. Altogether, our work demonstrates the ability to rationally engineer the composition and structure of a model biomolecular liquid.

Salt-dependent properties of a coacervate-like, self-assembled DNA liquid.

Liquid-liquid phase separation of a polymer-rich phase from a polymer-dilute solution, known generally as coacervation, has been observed in a variety of biomolecular systems. Understanding of this process, and the properties of the resulting liquid, has been hampered in typical systems by the complexity of the components and of the intermolecular interactions. Here, we examine a single-component system comprised entirely of DNA, in which tetravalent DNA nanostar particles condense into liquids through attractive bonds formed from basepairing interactions. We measure the density, viscosity, particle self-diffusion, and surface tension of NS-liquid droplets. The sequence- and salt-dependent thermodynamics of basepairing accounts for most properties, particularly indicating that particle transport is an activated process whose barrier is the breaking of a single bond, and that very few bonds are broken at the surface. However, more complex effects are also seen. The relation of density to salt shows that electrostatic screening compacts the NS particles. Further, the interrelation of the transport properties indicates a breakdown of the Stokes-Einstein relation. This observation, in concert with the low surface tension and single-bond transport barrier, suggests this DNA liquid has a heterogeneous, clustered structure that is likely enabled by internal NS particle flexibility. We discuss these results in comparison to other coacervate systems.

Effect of task-oriented training for people with stroke: a meta-analysis focused on repetitive or circuit training.

PURPOSE: The current meta-analysis reviewed evidence for effective task-oriented training focused on repetitive or circuit training after stroke. METHOD: Searches were conducted of randomized, controlled trials using task-oriented training. The quality of each study was assessed using the Physiotherapy Evidence Database (PEDro) scale. Eleven studies were analyzed regarding the magnitude of effect sizes (ESs) and categorized according to extremities focused upon for training, outcome measures, and study variables. This included duration and frequency of training and stroke stage. RESULTS: The PEDro scores ranged from 4 to 8 (median = 7). The overall ES of the 11 studies was large. The effects for lower extremities and both acute/sub-acute and chronic stage stroke were large and significant. Significant effects were also found for gait velocity, gait endurance, balance, timed up and go test, and strength of the lower extremities. There was no significant effect of training focused on upper extremities. Training with a duration of 2 weeks and frequency of 7 days a week had the greatest effects. CONCLUSIONS: Task-oriented training interventions are useful for improving muscle strength and gait related activities in both acute/sub-acute and chronic stroke patients. Although this meta-analysis provides evidence of task-oriented training for improving functioning after stroke, further studies are necessary to investigate the effects of training on upper extremities and the overall cost-effectiveness of such training.

Polymer capture by α-hemolysin pore upon salt concentration gradient.

We have measured the rate of capture of single molecules of sodium poly(styrene sulfonate) by α-hemolysin protein pore by varying applied voltage, pH, and the salt concentration asymmetry across the pore. We show that electrostatic interaction between the polyelectrolyte and the protein pore significantly affects the polymer capture rate in addition to the enhancement of drift arising from electrolyte concentration gradient. At higher pH values where the electrostatic interaction between the polymer and the α-hemolysin pore is repulsive, an antagonistic coupling with the drift induced by salt concentration gradient emerges. This antagonistic coupling results in a nonmonotonic dependence of the polymer capture rate on the salt concentration in the donor compartment. The coupling between the pore-polymer interaction and drift can be weakened by increasing the strength of the electric field that drives the polymer translocation. In contrast, at lower pH values where the polymer-pore interaction is attractive, a synergy with the additional drift from salt concentration asymmetry arises and the capture rate depends monotonically on the donor salt concentration. For higher pH, we identify two regimes for the enhancement of capture rate by salt concentration gradient: (a) drift-dominated regime, where the capture rate is roughly quadratic in the ratio of salt concentration in the receiver compartment to that in the donor compartment, and (b) antagonistic coupling regime at higher values of this ratio with a linear relation for the polymer capture rate.

The effects of obesity on fall efficacy in elderly people.

[Purpose] The aim of this study was to identify the effects of obesity on falls as a practical verification of the importance of obesity-targeting interventions as part of future fall prevention programs. [Subjects and Methods] The study involved 351 elderly people (172 men, 179 women) living in rural areas. The dependent variable, fall efficacy, was measured using the Falls Efficacy Scale, while the independent variables, body mass index (BMI) and visceral fat, were measured using the InBody 720. The Faces Pain Scale was used to measure pain. Mobility was measured using the Timed Up and Go Test, and balance ability was measured according to the duration subjects could stand on one foot with their eyes closed. Hierarchical multiple regression analysis was performed for the final data analysis. [Results] Investigation of the correlations between the variables revealed a negative correlation between fall efficacy and the other variables. Ultimatley, investigation of the causality of fall efficacy revealed that the BMI, pain, and mobility were influential factors. In other words, fall efficacy tends to be lower when there are higher degrees of obesity, increased pain, and decreased mobility. [Conclusion] To improve the fall efficacy of elderly people living in rural areas, pain management and the maintenance of physical functionality are required. The present study confirms that the elderly need continuous obesity management to lead healthy lives.

The effects of balance of low vision patients on activities of daily living.

[Purpose] This research investigated the relationship between balance measured by a TETRAX and activities of daily living (ADL) assessed by NEI-VFQ 25. The results should provide basic data for rehabilitation therapy for low-vision patients. [Methods] We used the NEI-VFQ-25 vision-related Activities of Daily Living evaluation, MMSE-K, and TETRAX to evaluate 30 low-vision outpatients at K hospital in Daejeon, South Korea from July 5 to July 23, 2012. We performed linear regression analysis using a statistical significance level of 0.05. [Results] Balance in the normal eyes open (NO) posture correlated with the normal eyes closed posture and age, but showed no correlation with NEI-VFQ 25. The ADL level correlated with monocular vision, female gender, cognition, and NO posture. These variables explained 54.4% of the aspects of their ADL. [Conclusion] This research proves that low vision adversely affects balance ability, and is influenced by type of vision, gender, and cognitive assessment.

Effect of Wrist Joint Restriction on Forearm and Shoulder Movement during Upper Extremity Functional Activities.

[Purpose] This study measured %isolation and investigated whether it shows a difference between the presence and absence of wrist joint restriction, as well as changes in muscle activity patterns. [Methods] Twenty subjects performed upper extremity functional movement in the Manual Function Test (MFT) with and without wrist restriction, and the muscle activities of the trapezius, middle deltoid, biceps brachii, triceps brachii, extensor carpi radialis, and flexor carpi radialis were recorded. When there were differences in muscle activation, %isolation was implemented and the changes in the muscle activity patterns were noted. [Results] In the grasping and pinching tasks, there was a significant increase in %isolation of the upper trapezius and a significant decrease in %isolation of the extensor carpi radialis. Carrying a cube task, %isolation of the upper trapezius and middle deltoid significantly increased, whereas %isolation of the triceps brachii and extensor carpi radialis significantly decreased. In the pegboard task, the %isolation values of the extensor carpi radialis and flexor carpi radialis significantly decreased. [Conclusion] The data of this study should be useful for therapists, who can employ the information as material for the education and treatment of patients with wrist joint restriction. Therapists may thus look for ways to improve the quality of mobility by predicting the complement mobility depending on the activity performed and then determine whether to facilitate or restrict mobility.

The Impact of Social Network Characteristics on Health among Community-Dwelling Older Adults in Korea: Application of Social Network Analysis.

Objectives: Population aging is a reality in most developed countries. In this era, an important health issue for these countries is promoting health and quality of life in the elderly population. Older adults' social networks are associated with health and quality of life. Therefore, this study examines the association between the characteristics of social networks (friendship networks) and the subjective well-being of community-dwelling older adults. Methods: This study was conducted between June 2015 and August 2015 with a total of 146 participants. The size and density of social networks were analyzed using social network analysis. Additionally, to investigate the impact of social networks on health, a multiple linear regression analysis was performed using NetMiner 4.0. Statistical significance was set at p < 0.05. Results: In terms of Model 1, which used social network characteristics as variables, the higher the out-degree (376.161) and in-closeness (201.825), the better the health. In contrast, the higher the in-degree (−279.167) and out-closeness (−52.620), the poorer the health. Regarding Model 2, which used sociodemographic characteristics as variables, the higher the out-degree (218.747) and in-closeness (170.075), the better the health. In addition, religion had a negative effect on health, and a high level of education had a positive effect on health. Conclusions: The findings suggest that higher out-degree and in-closeness intensity positively affect the health of older adults, but higher in-degree and out-closeness intensity negatively affect health. Therefore, health professionals should use appropriate strategies to increase the strength of social networks to improve the health of older adults living in the community.

Social interaction changes in people with intellectual disabilities through the application of equine-assisted intervention in Korea.

This study aims to provide basic information about the social interaction changes in people with intellectual disabilities through the application of equine-assisted intervention (EAI) in Korea. The subjects were 12 people with intellectual disabilities residing in a residential care facility in Korea. EAI was applied and consisted of communal activities and horseback riding. The intervention was conducted for 60 minutes each session, two sessions a week for 12 weeks. To determine the psychological aspects of the social interaction changes after the study cohort participated in the EAI, their social interaction anxiety, social phobia, and social avoidance and distress were measured. Their social interaction anxiety was measured using the Korean-Social Interaction Anxiety Scale (K-SIAS), and their social phobia was measured using the Korean-Social Phobia Scale (K-SPS). To measure their social avoidance and distress, the Korean-Social Avoidance and Distress scale (K-SADS) was used. The social interaction anxiety, social phobia, and social avoidance and distress results showed a continuous decrease after the application of EAI. Thus, the application of EAI, including communal activities and horseback riding, should be considered for people with intellectual disabilities in order to decrease their social interaction anxieties, phobias, and social avoidance and distress.

Correlational study between online friendship network and internet game disorder among university students.

PURPOSE: The purpose of this study was to provide basic information about the analysis of the correlation between online friendship network and internet game disorder among university students. METHODS: Study subjects were 77 university students. For analysis of online friendship among them, social network analysis was performed and the analysis of degree, closeness, and betweenness centrality was measured. Assessment of internet game disorder was done using the Korean version of Internet Gaming Disorder Scale. RESULTS: As per the results, the positive correlation showed between in-closeness centrality and internet gaming disorder (IGD) and the negative correlation showed between out-closeness centrality and internet gaming disorder. CONCLUSIONS: Online friendship is considered to contribute to the changes of internet game disorder level. Thus, in the relationship between online friendship and internet game disorder, closeness centrality should be considered, and causal relation analysis should be performed in further studies.

Effects of occupational balance on subjective health, quality of life, and health-related variables in community-dwelling older adults: A structural equation modeling approach.

Occupational balance is an important variable associated with health and quality of life. This study aimed to investigate the influence of occupational balance on health, quality of life, and other health-related variables using structural equation modeling. We analyzed data from 208 adults over 55 years old. Mean age of the participants was 70.21 years (SD 7.22). The research model for analysis was based on the results of previous studies addressing occupational balance and related variables such as stress, leisure satisfaction, life satisfaction, subjective health, quality of life, and participation. General fit indices of the final model were acceptable (x2/df = 1.708, p < .001, RMSEA = .058, TLI = .923, CFI = .929, and SRMR = .067). Although the size of effect was small to medium (.157-.249), occupational balance was identified as an independent variable directly or indirectly affecting subjective health, quality of life, and health-related variables in the final model. Our results showed that it is possible to improve subjective health and quality of life by promoting better occupational balance. Further studies developing an intervention program based on occupational balance are required to confirm the feasibility of the intervention and its effect on older adults' health and quality of life in real-life circumstances.

Sequence-Controlled Adhesion and Microemulsification in a Two-Phase System of DNA Liquid Droplets.

Membrane-less organelles, the liquid droplets formed via liquid-liquid phase separation (LLPS) of biomolecules in cells, act to organize intracellular components into multiple compartments. As a model for this process, and as a potential vehicle for in vitro exploitation of its properties, we explore here a synthetic multiphase LLPS system consisting of a mixture of self-assembled DNA particles. The particles, termed "DNA nanostars" (NSs), consist of four double-stranded DNA arms that each terminate in a single-stranded overhang. NSs condense into droplets due to overhang hybridization. Using two types of NSs with orthogonal overhangs enables the creation of two types of immiscible DNA droplets. Adhesion between the droplets can be tuned by the addition of "cross-linker NSs" that have two overhang sequences of each type. We find that increasing the amount of the cross-linker NSs decreases the droplet/droplet surface tension until a microemulsion transition occurs. Controlled droplet adhesion can also be achieved, without cross-linkers, using overhangs that can weakly hybridize. Finally, we show that solutes can be specifically targeted to the DNA phases by labeling them with appropriate sticky-ends. Overall, our findings demonstrate the ability to create a multiphase LLPS system, and to control its mesoscale configuration, via sequence design of the component molecules.

Dehydration entropy drives liquid-liquid phase separation by molecular crowding.

Complex coacervation driven liquid-liquid phase separation (LLPS) of biopolymers has been attracting attention as a novel phase in living cells. Studies of LLPS in this context are typically of proteins harboring chemical and structural complexity, leaving unclear which properties are fundamental to complex coacervation versus protein-specific. This study focuses on the role of polyethylene glycol (PEG)-a widely used molecular crowder-in LLPS. Significantly, entropy-driven LLPS is recapitulated with charged polymers lacking hydrophobicity and sequence complexity, and its propensity dramatically enhanced by PEG. Experimental and field-theoretic simulation results are consistent with PEG driving LLPS by dehydration of polymers, and show that PEG exerts its effect without partitioning into the dense coacervate phase. It is then up to biology to impose additional variations of functional significance to the LLPS of biological systems.

Upper Critical Solution Temperature (UCST) Behavior of Coacervate of Cationic Protamine and Multivalent Anions.

Complex coacervation is an emerging liquid/liquid phase separation (LLPS) phenomenon that behaves as a membrane-less organelle in living cells. Yet while one of the critical factors for complex coacervation is temperature, little analysis and research has been devoted to the temperature effect on complex coacervation. Here, we performed a complex coacervation of cationic protamine and multivalent anions (citrate and tripolyphosphate (TPP)). Both mixtures (i.e., protamine/citrate and protamine/TPP) underwent coacervation in an aqueous solution, while a mixture of protamine and sodium chloride did not. Interestingly, the complex coacervation of protamine and multivalent anions showed upper critical solution temperature (UCST) behavior, and the coacervation of protamine and multivalent anions was reversible with solution temperature changes. The large asymmetry in molecular weight between positively charged protamine (~4 kDa) and the multivalent anions (<0.4 kDa) and strong electrostatic interactions between positively charged guanidine residues in protamine and multivalent anions were likely to contribute to UCST behavior in this coacervation system.

Electrostatic Control of Polymer Translocation Speed through α­Hemolysin Protein Pore.

The electrostatic origins behind the speed of translocation of a uniformly charged flexible macromolecule through α-hemolysin (αHL) protein pores under a voltage are investigated using variations in pH and electrolyte concentration. We have measured durations of successful threading of poly(styrenesulfonate) through αHL at two different pH conditions, pH 4.5 and pH 7.5, under various salt concentration conditions. Salt concentrations in the donor (cis) and the recipient (trans) compartments influence the polymer translocation dynamics differently, depending on pH. At both pH 4.5 and pH 7.5, decreasing the cis salt concentration, cs,cis , results in faster polymer translocations. On the other hand, a decrease in trans salt concentration, cs,trans , retards the polymer transport process at pH 4.5, while at pH 7.5 the translocation time is observed to be independent of cs,trans . We present a theoretical model to calculate the translocation times from the free energy of the polymer along the translocation process to describe our experimental results. We show that the charge density of the polymer inside the nanopore is significantly affected by cs,cis , explaining the cis salt effect on the speed of polymer translocation. The trans salt effects are attributed to the electrostatic interaction between the polymer and the exit portion of the αHL pore, which is determined by the pH of the trans compartment. At low pH where the net charge of the end of the αHL is positive, the attractive electrostatic interaction in trans becomes stronger, as cs,trans decreases, resulting in delays in translocation process.

Determination of Molecular Weights in Polyelectrolyte Mixtures Using Polymer Translocation through a Protein Nanopore.

We introduce a single molecular analysis technique for the evaluation of molecular weight distributions of polyelectrolyte solutions by measuring translocation times of sodium polystyrenesulfonate (NaPSS) chains in a mixture passing through an α-hemolysin protein nanopore. The ionic current through an α-hemolysin nanopore is partially blocked transiently when the pore is occupied by a polymer chain with an average residence time proportional to the molecular weight of the polymer chain. We have measured the translocation times for an equimolar mixture of four different molecular weight NaPSS standards and observed distinct translocation time distribution peaks, each of which corresponding to the different components in the mixture. Size exclusion chromatography analyses were performed on the equimolar and equiweight NaPSS mixtures of the same components and compared with the translocation time measurements. The experimental results demonstrate that measuring translocation times can be a competitive technique for estimating the broad molecular weight distributions of polyelectrolytes.

Escherichia coli with autodisplayed Z-domain of protein A for signal amplification of SPR biosensor.

Generally, an immunoaffinity SPR biosensor detects a target analyte in a sample through highly selective adsorption by using the antigen-antibody interaction. For improving the sensitivity, various kinds of particles have been added to the already bound analytes on the SPR biosensor (sandwich assay). In this work, signal amplification was demonstrated by the expression of the IgG-binding Z-domain of protein A on the outer membrane of Escherichia coli via "Autodisplay". The amount of Z-domain of protein A expressed on the outer membrane was calculated to be 280,000 molecules per cell. In addition, the IgG-binding ability of the expressed protein was characterized using FACS analysis. The signal amplification of the SPR biosensor was performed in the sandwich assay format using a model of horseradish peroxidase (HRP); the limit of detection was determined to be significantly improved from 1 microg/ml to 1 ng/ml. Finally, myoglobin analysis was demonstrated for the medical diagnosis of cardiac diseases. The detection limit was estimated to be improved from 10 ng/ml to <1 ng/ml. These results show that Z-domain-displaying E. coli can be successfully used for the signal amplification of immunoaffinity biosensors, thereby improving the sensitivity and the limit of detection.