Surface Modification of Ultrasonic Cavitation by Surfactants Improves Detection Sensitivity of α-Synuclein Amyloid Seeds.

The rapid amplification and sensitive detection of α-synuclein (αSyn) seeds is an efficient approach for the early diagnosis of Parkinson's disease. Ultrasonication stands out as a promising method for the rapid amplification of αSyn seeds because of its robust fibril fragmentation capability. However, ultrasonication also induces the primary nucleation of αSyn monomers, deteriorating the seed detection sensitivity by generating seed-independent fibrils. In this study, we show that an addition of surfactants to the αSyn monomer solution during αSyn seed detection under ultrasonication remarkably improves the detection sensitivity of the αSyn seeds by a factor of 100-1000. Chemical kinetic analysis reveals that these surfactants reduce the rate of primary nucleation while promoting the fragmentation of the αSyn fibrils under ultrasonication. These effects are attributed to the modification of the ultrasonic cavitation surface by the surfactants. Our study enhances the utility of ultrasonication in clinical assays targeting αSyn seeds as the Parkinson's disease biomarker.

Relationship between scapular control during isometric shoulder flexion and scapular motion during baseball pitching: a cross-sectional study.

BACKGROUND: A baseball pitcher with decreased scapular control may not be able to achieve suitable scapular motion at maximum shoulder external rotation (MER) of baseball pitching during the pitching action. It is common clinically to compare scapular control of the throwing and non-throwing arms to detect side-to-side differences. However, it remains unclear whether scapular control is different between the throwing and non-throwing arms. Moreover, no data exist on the relationship between scapular control and scapular motion at MER of pitching. Primarily, this study aimed to compare scapular control during isometric shoulder flexion between the throwing and non-throwing arms. Secondly, this study aimed to investigate the relationship between scapular control during isometric shoulder flexion and scapular motion at MER of pitching. METHODS: Fifteen healthy collegiate baseball pitchers (age, 20.2 ± 1.9 years; height, 1.76 ± 0.05 m; body mass, 73.3 ± 6.7 kg) were recruited. An optical motion tracking system was used to assess scapular motion. Scapular control was defined as the amount of change in the scapular internal rotation angle, downward rotation angle, and anterior tilt angle during isometric shoulder flexion. We assessed scapular position at MER of pitching. RESULTS: No significant differences were detected for any of the scapular angles during isometric shoulder flexion between the throwing and non-throwing arms. The amount of change in the scapular internal rotation angle, scapular downward rotation angle, and scapular anterior tilt angle during isometric shoulder flexion had a significant relationship with the scapular downward rotation angle at MER. CONCLUSIONS: No side-to-side difference was noted in scapular control during isometric shoulder flexion in healthy collegiate baseball pitchers at the group level. Further studies are required to understand the side-to-side differences at the individual level. Additionally, there was a relationship between scapular control during isometric shoulder flexion and scapular position at MER. These findings suggest that clinicians may consider using isometric shoulder flexion to assess scapular control in baseball pitchers.

Posterior shoulder capsule of the dominant arm is stiffer in baseball players than that in nonthrowing population.

BACKGROUND: Posterior shoulder capsule tightness is one of the factors for shoulder injuries in overhead athletes. Recent studies have shown the posterior capsule of the dominant arm to be stiffer than that of the nondominant arm in baseball players. However, whether posterior capsule tightness in the dominant arm is exclusive to overhead athletes remains unknown. This study aimed to investigate whether the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population. METHODS: Fifteen male collegiate asymptomatic baseball players (baseball-player group) and fifteen male college students who did not partake in overhead sports (nonthrowing group) participated in this study. We measured the shear moduli of the middle and inferior posterior capsules, superior infraspinatus, inferior infraspinatus, teres minor, and posterior deltoid in the dominant arm by ultrasound shear wave elastography. We compared shear moduli between the two groups using an independent samples t-test and Mann-Whitney test. In addition, we investigated the correlation between the range of glenohumeral internal rotation and each shear modulus in each group using the Pearson correlation coefficient. RESULTS: The shear moduli in the baseball-player group were significantly higher than those in the nonthrowing group in both the middle posterior capsule (baseball-player group: 36.1 ± 5.6 kPa vs. nonthrowing group: 29.0 ± 8.6 kPa; P = .018) and inferior posterior capsule (37.1 ± 9.6 kPa vs. 27.9 ± 6.8 kPa; P = .002). However, no difference in the shear moduli of individual muscle groups was identified. The glenohumeral internal rotation range exhibited a statistically significant negative correlation with the shear modulus of the inferior posterior capsule in the baseball-player group (Pearson correlation coefficient = -0.586, P = .022). CONCLUSION: Our findings suggest that the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

Half-Time Heat Map Reveals Ultrasonic Effects on Morphology and Kinetics of Amyloidogenic Aggregation Reaction.

Ultrasonication has been recently adopted in amyloid-fibril assays because of its ability to accelerate fibril formation, being promising in the early stage diagnosis of amyloidoses in clinical applications. Although applications of this technique are expanding in the field of protein science, its effects on the aggregation reactions of amyloidogenic proteins are poorly understood. In this study, we comprehensively investigated the morphology and structure of resultant aggregates, kinetics of fibril formation, and seed-detection sensitivity under ultrasonication using ß2-microglobulin and compared these characteristics under shaking, which has been traditionally adopted in amyloid-fibril assays. To discuss the ultrasonic effects on the amyloid-fibril formation, we propose the half-time heat map, which describes the phase diagram of the aggregation reaction of amyloidogenic proteins. The experimental results show that ultrasonication greatly promotes fibril formation, especially in dilute monomer solutions, induces short-dispersed fibrils, and is capable of detecting ultra-trace-concentration seeds with a detection limit of 10 fM. Furthermore, we indicate that ultrasonication highly alters the energy landscape of an aggregation reaction due to the effect of ultrasonic cavitation. These insights contribute not only to our understanding of the effects of agitation on amyloidogenic aggregation reactions but also to their effective application in the clinical diagnosis of amyloidoses.