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Background/purpose Near-infrared ( NIR) light with high water absorption enables us to visualize the water content distribution appeared in the superficial skin layer. The light penetration depth with the wavelength of 1920 nm is almost 100 μm from the skin surface. Thus, the water distribution in the stratum corneum can be effectively imaged by detecting the wavelength band around 1920 nm. The aim of this article was to measure the time-lapse behavior of the tiny droplet of the moisturizer spreading on the skin surface by imaging in 1920 nm wavelength band for investigating the correlation with the traditional index of the skin condition such as the water content and transepidermal water loss ( TEWL). Methods Experiment is performed with three moisturizer products and seven volunteer subjects. The NIR image is acquired by an originally designed imaging scope equipped with the white light of the strong brightness [super continuum (SC) light], the bandpass filter with the center wavelength of 1920 nm, and the NIR image sensor. A tiny droplet of the moisturizer is put on the surface of the skin and the time-lapse images are saved. Each acquired image is analyzed from a view point of the droplet area and elapsed time for absorption into the skin. The water content and TEWL of all subjects are measured by the conventional electrical method for investigating the relationship with the measured droplet dynamics parameters. Results Elapsed time for moisturizer droplet to be absorbed into the skin, the droplet area just before absorption for three moisturizer products, skin water contents, and TEWL for seven subjects were measured and correlation coefficients for each parameters were calculated. It was found that the skin with higher water contents or lower TEWL absorbed the moisturizer faster and spreads moisturizer wider. Also absorption and spreading speed depend on moisturizer property (moisturizing or fresh) which is originated from the moisturizer constituents. Conclusion The correlation values between the moisturizer dynamics on the skin surface and the traditional index of the skin property were clarified. It was found that the skin with the high water content or low TEWL absorbs the moisturizer droplet fast. The spreading area depends not only on the skin property but on the constituents of the moisturizers. [ABSTRACT FROM AUTHOR]

Background/purpose We investigate the measurement sensitivity for the water content distribution in Near-infrared (NIR) imaging ranging up to 2 μm. Methods To evaluate the sensitivity, our attention is focused to the light penetration depth in the skin tissue because the thickness of a layer where the water content can be varied is very thin and deep light penetration decreases the signal variation. The light penetration depths in the wavelengths of 1300, 1450, and 1920 nm are calculated theoretically based on the Monte Carlo light transport simulation. Results It is clarified that the wavelength of 1920 nm gives the smallest penetration depth. A NIR imaging experiment is demonstrated to verify the difference of imaging sensitivity. The experiment result shows that the NIR image taken at 1920 nm gives the most sensitive measurement of the water content distribution in skin. [ABSTRACT FROM AUTHOR]

Recent studies have shown that hepatocyte growth factor (HGF) promotes the survival of embryonic motor neurons. However, it remains unclear whether HGF has trophic effects on mature motor neurons. In the present study, we examined the effects of HGF on adult motoneurons using the hypoglossal nerve transection model. In adult rats, neurons in the hypoglossal nucleus show a dramatic loss of choline acetyltransferase (ChAT) protein and mRNA after the axotomy. This reduction of ChAT was markedly prevented when HGF was administered continuously at the cut end of the nerve using an osmotic pump. The HGF receptor, c-met, protein and mRNA, which were faintly expressed in hypoglossal neurons under normal conditions, gradually increased and reached maximal levels 2 weeks after the axotomy. Administration of HGF reduced this c-met upregulation almost to normal levels. We also quantified HGF mRNA in the tongue and hypoglossal nucleus. The tongue contained abundant HGF mRNA, whereas the nucleus contained only low levels. Interestingly, the HGF mRNA level in the nucleus did not increase after the axotomy. These findings suggest that HGF is principally produced in the tongue and contributes to maintain ChAT expression in the nucleus. HGF produced in the hypoglossal nucleus alone after disconnection from the tongue may not be sufficient for the maintenance of the motor neuron function. Thus, exogenously applied HGF was effective to prevent the downregulation of ChAT activities. These findings provide a strong rationale for the potential clinical use of HGF for the treatment of motor neuron degenerative disease.