The Effect of a Synthetic Estrogen, Ethinylestradiol, on the hERG Block by E-4031.

Inhibition of K+-conductance through the human ether-a-go-go related gene (hERG) channel leads to QT prolongation and is associated with cardiac arrhythmias. We previously reported that physiological concentrations of some estrogens partially suppress the hERG channel currents by interacting with the S6 residue F656 and increase the sensitivity of hERG blockade by E-4031. Although these studies suggested that clinically used synthetic estrogens with similar structures have the marked potential to alter hERG functions, the hERG interactions with synthetic estrogens have not been assessed. We therefore examined whether ethinylestradiol (EE2), a synthetic estrogen used in oral contraceptives, affects hERG function and blockade by drugs. Supratherapeutic concentrations of EE2 did not alter amplitudes or kinetics of the hERG currents elicited by train pulses at 20 mV (0.1 Hz). On the other hand, EE2 at therapeutic concentrations reduced the degree of hERG current suppression by E-4031. The administration of EE2 followed by E-4031 blockade reversed the current suppression, suggesting that the interaction of EE2 and E-4031 alters hERG at the drug-binding site. The effects of EE2 on hERG blockade raised the possibility that other estrogens, including synthetic estrogens, can alter hERG blockade by drugs that cause QT prolongation and ventricular arrhythmias.

Time division ghost imaging.

In the conventional ghost imaging, it requires to illuminate a large number of patterns in order to reconstruct a good quality image under a low signal-to-noise ratio. We propose a new method so called time division ghost imaging to improve the quality of the image in noisy environment. In this procedure, the total number of patterns in the calculation process of the correlation function are divided into the sub-units with fewer illuminated patterns. Then one calculates the correlation for each sub-unit, and synthesizes the intermediate images obtained at each sub-unit. The validation and effectiveness of this method are confirmed by simulation and experiment, showing the robustness to noise.

Continued exposure of anti-cancer drugs to human iPS cell-derived cardiomyocytes can unmask their cardiotoxic effects.

Although the cardiotoxicity of anti-cancer drugs is an important issue, the underlying mechanisms remain unknown. To develop a sensitive assay system for cardiotoxicity, we examined effects of anti-cancer drugs on contractile functions of human iPS cell-derived cardiomyocytes by using non-invasive motion field imaging analysis with extended drug exposure time. We succeeded in continuously measuring stable contractile function. The continued exposure revealed that the difference in cardiotoxicity between cardiotoxic doxorubicin and less toxic erlotinib was more evident after 8 days of treatment than with 3 days of treatment, suggesting that continued exposure improved the predictive power for cardiotoxicity of anti-cancer drugs.