1988 Fiscal Year Final Research Report Summary
Basic study for the development of the instrument measuring water content of the skin surface stratum corneum with high frequency
| Project/Area Number |
61870041
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Dermatology
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TAGAMI Hachiro Tohoku University School of Medicine, 医学部, 教授 (60026911)
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| Co-Investigator(Kenkyū-buntansha) |
ROKUGO Masakazu Tohoku University School of Medicine, 医学部附属病院, 助手 (60183711)
HASHIMOTO Kumiko Tohoku University School of Medicine, 医学部附属病院, 助手 (00201707)
TADAKI Takayoshi Tohoku University School of Medicine, 医学部附属病院, 助手 (40188256)
OBATA Masaaki Tohoku University School of Medicine (20124563)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Stratum corneum / hydration / water-holding capacity / high frequency / simulation model / 生体シミュレイション / モデル / 角層水分 |
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| Research Abstract |
Because of its efficient water-holding capacity, normal stratum corneum (SC) can stay soft and flexible under any environmental conditions. However, there is thought to be a great difference in water content within the SC between the lowermost layer that faces the wet underlying living tissue and the superficial portion of the SC that is exposed to the relatively dry ambient atmosphere. We have developed a method to measure the hydration state of the skin surface employing skin conductance of high-frequency current of 3.5 MHz. However, the real depth of penetration of thie electric current into the skin was not fully determined in vivo.
In the present study we devised a simple and convenient in vitro model of the SC that simulates the in vivo setting of the SC. It consists of an isolated sheet of SC whose lower surface covers a pad of water-saturated filter paper, while the upper surface is exposed to the ambient atmosphere. By placing this model in environments with different relative
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humidities, we confirmed that the recorded conductance values correlated well with the actual water content of the SC (r=0.94).
Using a model having 5 layers of SC sheets, the water content of the innermost portion of the SC was estimated to be equivalent to about 90% of its dry weight, this level of water content remaining relatively constant over a wide range of ambient relative humidities except in extraordinary humid environments above 90% relative humidity when water began to accumulate excumulate excessively in the whole SC. In this 5-SC-sheet model, it was clearly demonstrated that there was an almost straight water concentration greadient from the lowermost layer to the uppermost layer of the SC.
We also confirmed that the skin conductance of the high grequency current correlated well with the water content of the superficial portion of the SC as well as with that of the whole SC, i.e. , is is a good parameter of the hydration state fo the superficial layer of the SC. In addition, we found that the electric current penetrates at least 5mm deep into the underlying water-saturated cutaneous tissue to show an optimal reading. Less
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