This paper describes a flexible stamping method, which employs a flexible film stamp made of polymeric materials. Unlike conventional hard stamps, the flexible film stamp does not require either the stamp or its substrate to be perfectly flat, which means large area stamping is easy to achieve at reduced cost. We confirmed this by replicating 50 µm square multi-mode optical polymer waveguides. The propagation loss of the waveguide is only 0.06 dB/cm at a wavelength of 850 nm, which satisfies the basic requirement for optical circuit boards, and the waveguide was used to fabricate a flexible optical circuit board with mechanically transferable (MT) connectors.
The age and species dependent characteristics of cutaneous esterase activity were examined in cultured keratinocytes of neonatal and adult humans and of rats at the age of 1, 3, 10, and 50 d. The existence of esterases was characterized using fluorescein-5-isothiocyanate diacetate under a confocal laser scanning microscope. In vitro hydrolysis of ethyl nicotinate (EN), an esterified prodrug of nicotinic acid, was investigated in homogenate of cultured keratinocytes, and the Michaelis-Menten parameters (V(max) and K(m)) of EN were evaluated. Together with development and growth of rats and humans, V(max) and V(max)/K(m) increased drastically, suggesting that esterases in keratinocytes develop markedly during the growth process. The affinity parameter, K(m), was almost the same among the ages in each species. These findings in cultured keratinocytes corresponded with our previous report using dissected skin specimens. Species differences in V(max), V(max)/K(m) and K(m) were also observed, and these parameters of EN hydrolysis in rats were significantly higher than that in humans. In conclusion, cultured keratinocytes can be an advantageous method with which to estimate cutaneous activation of ester prodrugs in humans and during the growth process.
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