Accuracy of a portable lower-limb muscle strength measuring device with a training function.

[Purpose] Quadriceps muscle strength is essential for daily living activities. Therefore, we developed a compact and simple lower limb muscle strength measuring device (LocomoScan [LCS]). This study aimed to compare LCS with other instruments to analyze its simplicity, reproducibility, and accuracy. [Participants and Methods] One hundred and four healthy university students (56 males and 48 females) were included in the study. The knee extension force was measured using LCS, and the knee extension torque was measured using other devices (Cybex). In addition, lower leg muscle mass was measured using a body composition meter. The reproducibility of LCS and the correlation between the knee extension torque and lower leg muscle mass were evaluated. [Results] The measurement reproducibility of LCS was significantly higher. The knee extension force confirmed the proportional relative reliability of Cybex with knee extension torque. A relationship between knee extension force and lower limb muscle mass was also observed, indicating that muscle mass cannot be estimated as muscle strength. [Conclusion] The high reproducibility of the knee extension force measurement using LCS demonstrates its potential as a portable alternative instrument for muscle strength measurement in clinical practice. Therefore, LCS device is a simple and effective tool for assessing muscle strength.

Intravenous anti-influenza drug oseltamivir will not induce torsade de pointes: Evidences from proarrhythmia model and action-potential assay.

We evaluated proarrhythmic risk of intravenous oseltamivir with chronic atrioventricular block canine model (n = 4) and action-potential assay on guinea-pig right ventricle (n = 5). Oseltamivir in doses of 3-30 mg/kg, i.v. did not induce torsade de pointes in the canine model, whereas that in concentrations of 30-300 µM decreased maximum rate of phase 0 depolarization, shortened action potential duration at 30%, 60% and 90% repolarization levels, but prolonged difference in action-potential duration between 30% and 90% repolarization levels in a concentration-related manner. These results indicate that oseltamivir will not induce torsade de pointes clinically, since it inhibits both inward and outward currents.

Clobutinol delays ventricular repolarization in the guinea pig heart: comparison with cardiac effects of HERG K+ channel inhibitor E-4031.

Clobutinol has been clinically reported to induce long QT syndrome. To clarify its cardiac electrophysiological properties, we compared effects of clobutinol on the isolated myocardium and anesthetized guinea pig heart with those of a hERG K channel blocker, E-4031. In isolated guinea pig ventricular tissues, clobutinol (3 microM) as well as E-4031 (10-100 nM) prolonged the action potential duration without affecting maximum upstroke velocity, but no further prolongation was observed after application of 30 microM clobutinol. In anesthetized closed-chest guinea pigs, clobutinol (1 and 10 mg/kg, intravenously) and E-4031 (0.01 and 1 mg/kg, intravenously) prolonged the QT interval and duration of the monophasic action potential (MAP) in a dose-dependent manner and at the same time increased the beat-to-beat variability of the MAP duration and reversed use-dependent prolongation of the MAP duration and triangulation of the MAP configuration. These results suggest that clobutinol delayed the ventricular repolarization and increased the proarrhythmic parameters linked to the hERG K channel inhibitor-induced torsade de pointes arrhythmias.