Yuta Suzuki

Total Synthesis and Cytotoxicity of Haterumalides NA and B and Their Artificial Analogues

The total synthesis of haterumalides NA and B, potent cytotoxic marine macrolides, was achieved by using B-alkyl Suzuki-Miyaura coupling and Nozaki-Hiyama-Kishi coupling as key steps. Compared to our first-generation approach for ent-haterumalide NA methyl ester, this second-generation synthesis yielded much more of the key intermediate. This synthesis established the relative stereochemistry of haterumalide B. Furthermore, the structure-cytotoxicity relationships of haterumalides were investigated. The combination of macrolide and side chain parts proved to be important to the cytotoxicity.

Second-generation total synthesis of haterumalide NA using B-alkyl Suzuki-Miyaura coupling.

Second-generation total synthesis of haterumalide NA, a potent cytotoxic marine macrolide, was achieved by using B-alkyl Suzuki-Miyaura coupling and Nozaki-Hiyama-Kishi coupling as key steps (1.2% in 33 steps). Compared to our first-generation approach, the second-generation synthesis is much improved in the yield of key intermediate.

Comparison of support leg kinetics between side-step and cross-step cutting techniques

The purpose of this study was to investigate differences in the support leg joint moment and moment power between side-step (SS) and cross-step (CS) cutting techniques with a prescribed 90° cutting angle. Ground reaction forces (1,000 Hz) and three-dimensional kinematics (250 Hz) of SS and CS cutting techniques were collected from 20 male college athletes. Normalised peak knee extension moment was larger in the SS technique than in the CS technique (0.40 ± 0.10 in SS; 0.26 ± 0.08 in CS). In the SS technique, the knee extensors ( − 0.10 ± 0.06 in SS; − 0.02 ± 0.04 in CS) and ankle plantarflexors ( − 0.12 ± 0.05 in SS; − 0.07 ± 0.03 in CS) did significantly more negative work (normalised). The direction change angle (40.5 ± 8.7° in SS; 33.0 ± 6.8° in CS) and the decrease in horizontal velocity of the centre of mass ( − 0.63 ± 0.23 m/s in SS; − 0.31 ± 0.23 m/s in CS) were significantly larger in the SS technique. These results suggest that the SS technique is an effective means of changing running direction at the expense of velocity of the centre of mass and that the CS technique is better for minimising the reduction in horizontal velocity of the centre of mass.

MASC: Automatic Sleep Stage Classification Based on Brain and Myoelectric Signals

Given brain and myoelectric signals taken from a mouse, how can we classify its sleep stages accurately? Classifying sleep stages is the fundamental problem in recent diagnoses and clinical researches. However, sleep staging suffers from a serious weakness, clinical experts visually inspect the brain and myoelectric signals to improve sleep staging accuracy. This is because recent diagnoses and clinical researches require classification accuracy at least 95% so as to enhance preciseness of their analyses. In this paper, we present an automatic classification method MASC based on the following three approaches: (1) it extracts effective features for fully representing each sleep stage property, (2) it classifies sleep stages by using temporal patterns of sleep stage transitions, and (3) it re-classifies sleep stages only for the results with low-confidence. As a result, MASC achieves more than 95% accuracy for both noisy and noiseless mice data.