Influences of different cognitive loads on central common neural drives to the ankle muscles during dual-task walking.

While dual-task walking with additional cognitive tasks may decrease walking performance, many studies have also shown increases in walking performance during dual tasks, especially as cognitive load increases. However, the neural mechanisms that cause changes in postural control during dual tasks according to the difference in cognitive load remain unclear. Therefore, this study aimed to investigate the influence of different cognitive loads on the neural control of muscle activity during dual-task walking using intra- and intermuscular coherence analyses. Eighteen healthy young adults were subjected to treadmill walking measurements in a single-task condition (normal walking without cognitive load) and two dual-task conditions (watching digits and digit 2-back task) with the measurements of reaction time to auditory stimulation. During walking with the digit 2-back task, stride-time variability was significantly reduced compared to that during normal walking, and reaction time was significantly delayed compared to those during normal walking and walking with watching digits. The peak value of the tibialis anterior intramuscular coherence in the beta band (15-35 Hz) significantly increased during walking with the digit 2-back task than that during walking with watching digits. The present results suggest that young adults can increase their central common neural drive and decrease their walking variability for concentration on cognitive tasks during dual-task walking.

Reductive SN 2' Reaction of Epoxydienoate with Borane and its Application to the Synthesis and Structural Revision of an Antitumor Active Torrubiellutin Analogue.

A reductive SN 2' reaction of epoxydienoates and epoxyenoates with borane was developed to afford skipped dienoates and unconjugated enoates with trisubstituted Z-alkene linked to asymmetric centers on one side or both sides. This reaction was successfully applied to the alternative synthesis of an antitumor active artificial analogue of torrubiellutin C. A geometric isomer for α,ß-unsaturated amide of the artificial analogue was also synthesized. These syntheses clarified the true structure of the antitumor active artificial analogue of torrubiellutin C.

Isoelectric point-amyloid formation of α-synuclein extends the generality of the solubility and supersaturation-limited mechanism.

Proteins in either a native or denatured conformation often aggregate at an isoelectric point (pI), a phenomenon known as pI precipitation. However, only a few studies have addressed the role of pI precipitation in amyloid formation, the crystal-like aggregation of denatured proteins. We found that α-synuclein, an intrinsically disordered protein of 140 amino acid residues associated with Parkinson's disease, formed amyloid fibrils at pI (= 4.7) under the low-sodium phosphate conditions. Although α-synuclein also formed amyloid fibrils at a wide pH range under high concentrations of sodium phosphate, the pI-amyloid formation was characterized by marked amyloid-specific thioflavin T fluorescence and clear fibrillar morphology, indicating highly ordered structures. Analysis by heteronuclear NMR in combination with principal component analysis suggested that amyloid formation under low and high phosphate conditions occurred by distinct mechanisms. The former was likely to be caused by the intermolecular attractive charge-charge interactions, where α-synuclein has +17 and -17 charges even with the zero net charge. On the other hand, the latter was caused by the phosphate-dependent salting-out effects. pI-amyloid formation may play a role in the membrane-dependent amyloid formation of α-synuclein, where the negatively charged membrane surface reduces the local pH to pI and the membrane hydrophobic environment enhances electrostatic interactions. The results extend the supersaturation-limited mechanism of amyloid formation: Amyloid fibrils are formed under a variety of conditions of decreased solubility of denatured proteins triggered by the breakdown of supersaturation.