In our previous study, the viscoelasticity of the radial artery wall was estimated to diagnose endothelial dysfunction using a high-frequency (22 MHz) ultrasound device. In the present study, we employed a commercial ultrasound device (7.5 MHz) and estimated the viscoelasticity using arterial pressure and diameter, both of which were measured at the same position. In a phantom experiment, the proposed method successfully estimated the elasticity and viscosity of the phantom with errors of 1.8 and 30.3%, respectively. In an in vivo measurement, the transient change in the viscoelasticity was measured for three healthy subjects during flow-mediated dilation (FMD). The proposed method revealed the softening of the arterial wall originating from the FMD reaction within 100 s after avascularization. These results indicate the high performance of the proposed method in evaluating vascular endothelial function just after avascularization, where the function is difficult to be estimated by a conventional FMD measurement.

ABSTRACT:Triphenylmethyl methacrylates having alkoxy groups, or mesogenic groups with alkyleneoxy spacer, as p-substituents of one of the phenyl groups were synthesized. Although the monomers and polymers were considerably unstable against hydrolysis, polymers could be obtained by radical polymerization by careful handling of the compounds. Anionic initiators, such as butylithium, usually failed to give high polymers. This seems to be because of the difficulty in obtaining completely dry monomers for anionic polymerization. Triad isotacticity of the polymers was evaluated after converting the polymers into poly(methyl methacrylate)s. Polymers obtained not only by anionic polymerization but also by radical polymerization showed considerably high isotacticity. The effects of the substituents on the isotacticity of the polymers are described.KEY WORDS Triphenylmethyl Metacrylate / Radical Polymerization / Anionic Polymerization/ Tacticity / Poly(methyl methacrylate) / Mesogen /

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