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-104- Lipids/Barrier 9/5 Room-A
ALTERATION OF b-GLUCOCEREBROSIDASE ACTIVITY IN PSORIATIC SKIN.
Mariko Hara1, Yoshikazu Uchida1, Yasuo Kubota2, Yoko Kawa2, Sumiko Hamanaka3, Masako Mizoguchi2
1Kanebo Cosmetics Lab., 2Department of Dermatology, St. Marianna University, School of Medicine, Kanagawa, 3Department of Dermatology, Yamaguchi Rosai Hospital,Yamaguchi,Japan.
Although both abnormal epidermal differentiation and the defective of epidermal barrier function are aware in psoriatic skin (Ps), the relationship between the impairment of stratum corneum (SC) lipid formation and barrier dysfunction is not clarified. To elucidate whether barrier dysfunction in Ps is due to the alteration of the processing of ceramide (Cer) in SC, we examined the activities of b-glucocerebosidase (GCase) and sphingomyelinase (SPMase), which are hydrolytic enzymes involved in Cer synthesis, in 15 Ps epidermis (PsE) compared with normal human epidermis (NE) obtained from 54 healthy subjects (6-84 yrs). Although there were no apparent differences in enzyme activity due to age, gender or the part of body, a significant linear correlation was found between the two enzyme activities in NE (p<0.001). On the other hand, the activity of GCase in involved PsE was significantly higher than that of NE, while activity in uninvolved epidermis was lower than that of NE (p<0.01). GCase was studied histochemically by in situ zymography using the synthetic fluorescent as a substrate. A bright fluorescence was observed in the stratum granular (SG) layer in NE. In contrast, the lower layer of the SC, but not SG, was stained in the involved skin but clear staining was not visible in the uninvolved epidermis. This is the first evidence that GCase activity is altered in PsE. This alteration might participate in epidermal barrier impairment by changing Cer metabolism in SC.
-105- Lipids/Barrier 9/5 Room-A
A NEW ASSAY SYSTEM OF SPHINGOMYELIN DEACYLASE AND THEIR BIOCHEMICAL CHARACTERIZATION IN ATOPIC STRATUM CORNEUM.
Kazuhiko Higuchi1, Reiko Takara1, Junko Hara1, Junko Arikawa1, Makoto Kawashima1, Genji Imokawa2.
1Department of Dermatology, Tokyo WomenŽÕs Medical College, Tokyo, 2Biological Science Laboratories Kao Corporation, Tochigi, Japan.
Previously we have shown using choline-labeled sphingomyelin (SM) as a substrate that in the stratum corneum (SC) of patients with atopic dermatitis (AD), there was a high activity of SM deacylase which catalyzes the hydrolysis of SM to yield sphingosylphosphorylcholine (SPC) instead of ceramide. In this study, we prepared [1-14C] palmitoyl-SPC to assess quantitatively SM deacylase activity and characterized biochemical properties of this enzyme involved in atopic SC. The optimal pH for enzyme activity was found to be approximately 5.0. HPLC-gel filtration demonstrated that SM deacylase was distinct in elution pattern from ceramide-producing enzyme, sphingomyelinase (SMase). On isoelectric focusing, the pI value was 4.2 and a similar value was also observed in samples from normal SC. These findings suggest that the abnormally expressed SM deacylase is competitive with SMase in utilizing SM as a substrate, resulting in the decreased levels of ceramides in the SC of AD patients
-106- Lipids/Barrier 9/5 Room-A
MEASUREMENT OF FREE WATER AND BOUND WATER CONTENT IN WOUNDED STRATUM CORNEUM BY DIELECTRIC METHOD.
Mitsunobu Kobayashi,Satoru Naito.
Kao Corporation,Tochigi,Japan.
Time domain reflectometry was applied to both normal and wounded human skin to investigate the role of water in stratum corneum(S.C.). In this study, dielectric property of human skin in a range of 107 to 1010 Hz was expressed by the superposition of two relaxation processes and DC conductivity as an approximation. The faster relaxation process is that of free water, and the slower process was considered to be that of bound water because its relaxation time was in the range of the previous reports. Wounded skin was made by the two step treatment of normal skin: the first one is acetone/ether(1/1vol.) treatment and the second one is water treatment. Following results were derived: 1)When we increased free water content of extremely dried S.C. by changing humidity or adding small amount of water, bound water content first increased simultaneously and then the bound water content showed the constant value. 2)Bound water content of wounded S.C. was lower than that of normal skin. Those results indicates that interceller lipid or NMF (amino acid and so on) are indispensable to keep bound water content of S.C. at a normal level. Acknowledgment : The method described above was developed from the joint work with deceased professor Mashimo of Tokai Univ..
-107- Lipids/Barrier 9/5 Room-A
EFFECT OF HYDRATION ON THE FLUIDITY OF INTERCELLULAR MEMBRANE OF STRATUM CORNEUM.
Katsuhiro Maruyama1, Hitoshi Masaki1, Minoru Ito1, Hiromu Sakurai2.
1Shiga Research Group, Noevir Co. Ltd., Shiga, 2Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto,Japan.
Electron spin resonance (ESR), differential scanning calorimetry (DSC),small angle X-ray scattering (SAXS) have been used to study the relationship between hydration level in the stratum corneum and membrane fluidity as molecular mobility of the intercellular lamellar lipids. Results of ESR with spin label agents showed that decreasing the water content particulary lower the maximum bond-water content in the stratum corneum leads to a drastic decrease in membrane fluidity below the temperature at 35-40¡î. The phase transition of stratum corneum lipids was confirmed by DSC in which the phase transition was observed at 36-38¡î, and both the transition temperature and enthalpy change decreased with the hydration level. These results suggest that the interfacial area of lipid molecule in orthorhombic lateral packing on lamellar membrane expands by intercalation of water molecules. In support of the consideration, SAXS measurements indicated that the repeat distance between the lipid lamella in intact stratum corneum almost unchanged at approximetly 12.5 nm in the range of 0-49 wt% hydration, indicating that hydration level hardly affected to the longitudinal swelling of lipid membrane. On the basis of these results, we propose here that hydration of the stratum corneum increases the membrane fluidity due to the decrease of lateral packing density of lipid alkyl chains.
-108- Lipids/Barrier 9/5 Room-A
THE EFFECT OF SKIN CLEANSING PRODUCTS ON EPIDREMAL PERMIABILITY BARRIER.
Minehiro Okuda.
Tochigi Research laboratories, Kao Corporation, Tochigi, Japan.
We think that appropriate washing with good skin cleansing products are very useful to keep healthy and beautiful skin.Then we purpose to develop new skin cleansing products which keep the epidermal permeability barrier and the good skin condition. We used two permeability barrier measurement which were transepidermal water loss value and penetration of riboflavine to evaluate new skin cleansing products. We made sure that pH value of product is very effective for epidermal permeability barrier function.We think that most useful pH value is pH5. And we also examined the effect of monoglyceride to degree of extraction from skin and keep epidermal permeability barrier.
-109- Lipids/Barrier 9/5 Room-A
EPIDERMAL BARRIER DISRUPTION INDUCED BY EXCESS SEBUM SECRETION.
Tatsuo Yamamura, Katsuhiro Maruyama, Hitoshi Masaki, Minoru Ito.
Shiga Research Group, Noevir Co. Ltd., Shiga, Japan.
We have reported that the epidermal barrier function was impaired by an excess secretion of sebum. In this study, to clarify the mechanisms of the impairment of the barrier function due to sebum, we examined the effects of sebum components on TEWL and morphology of corneocytes in hairless mouse. Oleic acid which is a major free fatty acid in sebum, showed a dry and scaly skin at 3 days after treatment, and gave a prominent increase of TEWL. In contrast, squalene and triolein did not exhibit any changes on the both of TEWL and corneocyte morphology. Stratum corneum which was treated with oleic acid, showed the decrease of bound water contents and the increase of membrane fluidity of the intercellular lipids lamellar. From these results, it was suggested that the impairment of epidermal barrier function due to sebum was caused by a change of the structure of intercellular lipids lamellar due to the migration of sebum components.
-110- Lipids/Barrier 9/5 Room-A
MEASUREMENT OF FREE WATER AND BOUND WATER CONTENT BY DIELECTRIC METHOD IN STRATUM CORNEUM OF SKIN DISEASES.
Shu Sasai1, Ya-Xian Zhen1, Satoru Naito2, Hachiro Tagami1.
1Department of Dermatology, Tohoku University School of Medicine, Sendai, 2Kao Corporation, Tochigi, Japan.
We can use high-frequency conductance as a parameter for the hydration state of the skin surface in vivo. The water contained in the stratum corneum is classified into two fractions, i.e. bound water, which binds to the polar components of the stratum corneum, and free water appearing only in a hydrated state based on the results of the past measurements performed in vitro ; under this condition water is distributed uniformly in the stratum corneum unlike that in vivo. There have been no data obtained in vivo in regard to free and bound water fractions. In this study, we measured water fractions in the stratum corneum of various skin lesions by measuring its dielectric properties, and compared them with the results obtained with the skin surface hygrometry.