The use of model matching video analysis and computational simulation to study the ankle sprain injury mechanism

Lateral ankle sprains continue to be the most common injury sustained by athletes and create an annual healthcare burden of over $4 billion in the U.S. alone. Foot inversion is suspected in these cases, but the mechanism of injury remains unclear. While kinematics and kinetics data are crucial in understanding the injury mechanisms, ligament behaviour measures - such as ligament strains - are viewed as the potential causal factors of ankle sprains. This review article demonstrates a novel methodology that integrates model matching video analyses with computational simulations in order to investigate injury-producing events for a better understanding of such injury mechanisms. In particular, ankle joint kinematics from actual injury incidents were deduced by model matching video analyses and then input into a generic computational model based on rigid bone surfaces and deformable ligaments of the ankle so as to investigate the ligament strains that accompany these sprain injuries. These techniques may have the potential for guiding ankle sprain prevention strategies and targeted rehabilitation therapies

The use of model matching video analysis and computational simulation to study the ankle sprain injury mechanism

Lateral ankle sprains continue to be the most common injury sustained by athletes and create an annual healthcare burden of over $4 billion in the U.S. alone. Foot inversion is suspected in these cases, but the mechanism of injury remains unclear. While kinematics and kinetics data are crucial in understanding the injury mechanisms, ligament behaviour measures - such as ligament strains - are viewed as the potential causal factors of ankle sprains. This review article demonstrates a novel methodology that integrates model matching video analyses with computational simulations in order to investigate injury-producing events for a better understanding of such injury mechanisms. In particular, ankle joint kinematics from actual injury incidents were deduced by model matching video analyses and then input into a generic computational model based on rigid bone surfaces and deformable ligaments of the ankle so as to investigate the ligament strains that accompany these sprain injuries. These techniques may have the potential for guiding ankle sprain prevention strategies and targeted rehabilitation therapies

Molecular-Level Insights into N–N π‑Bond Rotation in the pH-Induced Interfacial Isomerization of 5‑Octadecyloxy-2-(2-pyridylazo)phenol Monolayer Investigated by Sum Frequency Generation Vibrational Spectroscopy

In-situ and real-time characterization of molecular structure of pH stimuli-responsive assembling systems at interfaces is critical to understand the nature of interfacial driving force and weak molecular interaction behind such reactions and provide important clues to control them in a desired manner. In this study, sum frequency generation vibrational spectroscopy (SFG-VS) has been applied, supplemented by surface pressure (π)–area (<i>A</i>) isotherm measurements, and Brewster angle microscopy images, to investigate the interfacial tautomerism and isomerization reactions occurring in 5-octadecyloxy-2-(2-pyridylazo)­phenol (PARC18) monolayer at air/buffer solution interface in situ. The isomerization mechanism was examined by measuring interfacial structure of PARC18 molecule at various subphase pH. Time-dependent change of the SFG intensity of the characteristic band was kinetically measured after spreading PARC18 chloroform solution onto different subphase pH buffer solutions. It was found that hydrazone form prevails on the air/water interface in acidic and neutral conditions while azo form dominates at subphase pH ≥ 11.6. The hydrazone form adopts a planar geometry at pH = 4.5 and 7.0, whereas the azo form adopts a nonplanar cis or cis-like conformation. It was indicated that the trans–cis isomerization processes follow a rotation mechanism. The deprotonation rate constant was deduced to be 0.20–0.42 M^–1 s^–1 at pH = 10.3–12.6. This is the first reported application of SFG-VS to elucidate the isomerization mechanism and deduce the deprotonation rate constant of azoaromatic compounds at interface. Resulting from this study will aid in a better understanding of the interfacial pH-controlled assembly processes

Interfacial Structure and Transformation of Guanine-Rich Oligonucleotides on Solid Supported Lipid Bilayer Investigated by Sum Frequency Generation Vibrational Spectroscopy

Lipid membrane-anchored guanine-rich oligonucleotides with non-Watson–Crick structures can perform structure transformation in a controllable and reversible manner upon the external stimuli. Elucidating the mechanisms of their interaction and transformation is the key to understand medical applicability and functioning feasibility of these oligonucleotides. In this study, the molecular structure and interfacial transformation kinetics of guanine-rich oligonucleotides at model cell membrane were investigated by sum frequency generation vibrational spectroscopy (SFG-VS) in real time and <i>in situ</i>. The conformations of oligonucleotides are obtained by analyzing the SFG spectra in the “fingerprint” region. The results indicate that the electrostatic interaction and hydrophobic interaction are both important to the interfacial adsorption and transformation of oligonucleotides. The tilt angles of oligonucleotides with different conformations were also calculated. Molecular insights into interfacial oligonucleotides will help researchers to control the oligonucleotide–lipid membrane interactions in a desired manner and improve the reproductivity, stability, and reversibility of oligonucleotide-based applications

A simulation study to investigate ankle sprain mechanisms

Ankle sprain is the most common injury in sports, but the mechanism of injury may not always be clear. Sports-related injury mechanisms can be studied through various approaches: cadaveric experiments, kinematics, biomechanics, and computational modeling. The advantage of computer simulation is the ability to separate motions and study them individually

Specific Ion Interaction Dominates over Hydrophobic Matching Effects in Peptide–Lipid Bilayer Interactions: The Case of Short Peptide

Insertion of short peptides into the cell membrane is energetically unfavorable and challenges the commonly accepted hydrophobic matching principle. Yet there has been evidence that many short peptides can penetrate into the cells to perform the biological functions in salt solution. On the basis of the previous study (J. Phys. Chem. C 2013, 117, 11095−11103), here we further performed a systematic study on the interaction of mastoparan with various neutral lipid bilayers with different lipid chain lengths in situ to examine the hydrophobic matching principle in different aqueous salt environments using sum frequency generation vibrational spectroscopy. It is found that the hydrophobic matching is the dominant driving force for the association of MP with a lipid bilayer in a pure water environment. However, in a kosmotropic ion environment, the hydration of ions can overcome the hydrophobic mismatching effects, leading to the insertion of MP into lipid bilayers with much longer hydrophobic lengths. When the hydrophobic thickness of the bilayer is much longer than MP’s hydrophobic length, MP diffuses on a single monolayer, rather than spanning the bilayer to prevent the exposure of the hydrophilic part of MP to the lipid hydrophobic moiety. Findings from the present study suggest that the interaction between the positively charged choline group of a lipid and kosmotropic ions could be an important step for effective peptide insertion into a cell membrane. Results from our studies will provide an insight into how the short peptides form the ion channel in a thick membrane and offer some ideas for cellular delivery

Image1_Traditional Uses, Chemistry, Pharmacology, Toxicology and Quality Control of Alhagi sparsifolia Shap.: A Review.TIF

Alhagi sparsifolia Shap. (Kokyantak) is a ethnic medicine used in the Uyghur traditional medicine system for the treatment of colds, rheumatic pains, diarrhea, stomach pains, headaches, and toothaches, in addition to being an important local source of nectar and high-quality forage grass, and playing a crucial role in improving the ecological environment. Currently, approximately 178 chemical constituents have been identified from A. sparsifolia, including flavonoids, alkaloids, phenolic acids, and 19 polysaccharides. Pharmacological studies have already confirmed that A. sparsifolia has antioxidant, anti-tumor, anti-neuroinflammatory effects, hepatoprotective effects, renoprotective effects and immune regulation. Toxicological tests and quality control studies reveal the safety and nontoxicity of A. sparsifolia. Therefore, this paper systematically summarizes the traditional uses, botany, phytochemistry, pharmacology, quality control and toxicology of A. sparsifolia, in order to provide a beneficial reference of its further research.</p

A simulation study to investigate ankle sprain mechanisms

Ankle sprain is the most common injury in sports, but the mechanism of injury may not always be clear. Sports-related injury mechanisms can be studied through various approaches: cadaveric experiments, kinematics, biomechanics, and computational modeling. The advantage of computer simulation is the ability to separate motions and study them individually