Dissecting current rectification through asymmetric nanopores.

Rectification, the tendency of bidirectional ionic conductors to favor ion flow in a specific direction, is an intrinsic property of many ion channels and synthetic nanopores. Despite its frequent occurrence in ion channels and its phenomenological explanation using Eyring's rate theory, a quantitative relationship between the rectified current and the underlying ion-specific and voltage-dependent free energy profile has been lacking. In this study, we designed nanopores in which potassium and chloride current rectification can be manipulated by altering the electrostatic pore polarity.

Cationic Polysaccharides Bind to the Endothelial Cell Surface Extracellular Matrix Involving Heparan Sulfate.

Cationic polysaccharides have been extensively studied for drug delivery via the bloodstream, yet few have progressed to clinical use. Endothelial cells lining the blood vessel wall are coated in an anionic extracellular matrix called the glycocalyx. However, we do not fully comprehend the charged polysaccharide interactions with the glycocalyx.

A pilot study of the contribution of energy-dense Caribbean diets to acrylamide exposure with associated health risks for a population of university students in Trinidad and Tobago.

Previous studies on university students have indicated a significant decline in the consumption of fruits and vegetables complemented by an increase in energy-dense foods. The food toxicant, acrylamide, typically occurs in carbohydrate-rich, energy-dense foods that have been heated. Hence, this work presents an estimated dietary acrylamide exposure for university students in Trinidad and Tobago.

Mathematical modeling of microscale biology: Ion pairing, spatially varying permittivity, and Born energy in glycosaminoglycan brushes.

Biological macromolecules including nucleic acids, proteins, and glycosaminoglycans are typically anionic and can span domains of up to hundreds of nanometers and even micron length scales. The structures exist in crowded environments that are dominated by multivalent electrostatic interactions that can be modeled using mean-field continuum approaches that represent underlying molecular nanoscale biophysics. We develop such models for glycosaminoglycan brushes using steady state modified Poisson-Boltzmann models that incorporate important ion-specific (Hofmeister) effects.

Primary Microbial Succession in the Anchialine Ecosystem.

When new land is created, initial microbial colonization lays the foundation for further ecological succession of plant and animal communities. Primary microbial succession of new aquatic habitats formed during volcanic activity has received little attention. The anchialine ecosystem, which includes coastal ponds in young lava flows, offers an opportunity to examine this process.

The role of the cell surface glycocalyx in drug delivery to and through the endothelium.

Cell membranes are key interfaces where materials engineering meets biology. Traditionally regarded as just the location of receptors regulating the uptake of molecules, we now know that all mammalian cell membranes are 'sugar coated'. These sugars, or glycans, form a matrix bound at the cell membrane via proteins and lipids, referred to as the glycocalyx, which modulate access to cell membrane receptors crucial for interactions with drug delivery systems (DDS).

Lisfranc injury: Prevalence and maintaining a high index of suspicion for optimal evaluation.

Objectives: To quantify the long-term prevalence of game-related Lisfranc trauma in college football on artificial turf and natural grass.

Methods: 32 universities were evaluated over 10 competitive seasons across all Football Bowl Subdivision (FBS) conferences. Outcomes of interest included injury severity, injury category, primary type of injury, player and skill position, injury mechanism and situation, elective imaging and surgical procedures, and field conditions.

Ion Pairing and Dielectric Decrement in Glycosaminoglycan Brushes.

Cell-surface polysaccharides are essential to many aspects of physiology, serving as a highly conserved evolutionary feature of life and as an important part of the innate immune system in mammals. Here, as simplified biophysical models of these sugar coatings, we present results of molecular dynamics simulations of hyaluronic acid and heparin brushes that show important effects of ion pairing, water dielectric decrease, and coion exclusion. As in prior studies of macromolecular crowding under physiologically relevant salt concentrations, our results show equilibria with electroneutrality attained through screening and pairing of brush anionic charges by monovalent cations at the atomistic detail.

Exploring Structure⁻Property Relationships of GAGs to Tailor ECM-Mimicking Hydrogels.

Glycosaminoglycans (GAGs) are a class of linear polysaccharides that are ubiquitous in the extracellular matrix (ECM) and on cell surfaces. Due to their key role in development, homeostasis, pathogenesis, and regeneration, GAGs are increasingly used in the design of ECM-mimicking hydrogels to stimulate tissue formation and regenerative processes via specifically orchestrated cell-instructive signals. These applications first and foremost build on the ability of GAGs to effectively bind, protect, and release morphogens.

Moment analysis of near-equilibrium binding interactions during electrophoresis.

The electrophoretic transport of three chemically reacting species, two of which can bind reversibly to form the third, is analyzed mathematically. The species are assumed to move horizontally through a long channel with different electrophoretic mobilities and diffusion coefficients. By considering small perturbations of the system about equilibrium or when one of the two binding species is much more abundant than the other, the governing advection-reaction-diffusion equations can be linearized and studied via the method of moments.

Resolution of multiple ssDNA structures in free solution electrophoresis.

By using high concentrations of buffer, electroosmotic flow within uncoated channels of a microfluidic chip was minimized, allowing the free solution electrophoretic separation of DNA. More importantly, because of the ability to efficiently dissipate heat within these channels, field strengths as high as 600 V/cm could be applied with minimal Joule heating (<2 degrees C). As a result of the higher field strengths, separations within an 8-cm-long channel were achieved within a few minutes.

Radiographic findings of the upper extremity in collegiate rodeo athletes.

Introduction And Purpose: Upper-extremity trauma has been extensively studied in traditional sports to reduce predisposition to injury. Limited attention has been directed toward nontraditional, high-collision sports such as rodeo. Therefore, the purpose of this study was to quantify radiographic changes of the upper extremity in collegiate rodeo athletes after seasonal competition.

Efficacy of stairclimber versus cycle ergometry in postoperative anterior cruciate ligament rehabilitation.

Objective: To examine the effective use of stair climbing as an alternative to cycling for knee rehabilitation in an actual injured sport population.

Design: Repeated-measures multivariate analyses with data collected during anterior cruciate ligament (ACL) rehabilitation.

Setting: Clinical rehabilitation setting following ACL reconstruction.