Stratum Corneum Turnover Time Research Articles

Fluorescence spectral imaging of dihydroxyacetone on skin in vivo.

Dihydroxyacetone (DHA) has been proposed as a potential alternative to dansyl chloride for use as a fluorescence marker on skin to assess stratum corneum turnover time in vivo. However, the fluorescence from DHA on skin has not been adequately studied. To address this void, a noninvasive, noncontact spectral imaging system is used to characterize the fluorescence spectrum of DHA on skin in vivo and to determine the optimal wavelengths over which to collect the DHA signal that minimizes the contributions from skin autofluorescence. The DHA-skin fluorescence signal dominates the 580-680 nm region of the visible spectrum when excited with ultraviolet radiation in the 320-400 nm wavelength region (UVA). An explanation of the time-dependent spectral features is proposed in terms of DHA polymerization and binding to skin.

Biophysical changes after mechanical injury of the stratum corneum in normal skin.

Scrubbing off the stratum corneum with a rough towel after soaking in warm water is a bathing custom unique to Korea. However, Korean dermatologists have advised against this practice due to the potential harm that it may cause, though there is little data to support this advice. This study aimed to evaluate the changes in biophysical characteristics after such mechanical injury of stratum corneum, as reflected by water-holding capacity, stratum corneum barrier function, and stratum corneum turnover time (SCTT). 10 Korean female volunteers (aged 19-34 years) were enrolled in this study to investigate the acute effects and 32 volunteers (aged 19-49 years) the chronic effects. After soaking in warm water (36 degrees C) for 5 min, the flexor surfaces of the forearms were scrubbed with a rough towel. The volunteers' forearms were divided into 4 compartments, and each compartment was scrubbed 0, 5, 10, and 15x, respectively. After a single injury of the stratum corneum, there was an initial decrease in water-holding capacity until 6 h. Thereafter, it increased until day (D) 3, when it began to descend to the normal range. The transepidermal water loss (TEWL) values also peaked at D2 and declined thereafter. However, there were no changes in either water-holding capacity or skin barrier function, and only the SCTT was significantly shortened, after chronic injury of the stratum corneum.

The Effects of an Alpha Hydroxy Acid (Glycolic Acid) on Hairless Guinea Pig Skin Permeability

The barrier integrity of hairless guinea pig skin after treatment with an alpha hydroxy acid was assessed through in vivo topical application of an oil-in-water emulsion containing 5 or 10% glycolic acid at pH 3.0. The control was a commercial moisturizing lotion, pH 7.8. A dosing regimen for the glycolic acid formulations that was tolerated by the hairless guinea pigs and significantly decreased stratum corneum turnover time was determined using the dansyl chloride staining technique. Once-daily dosing of hairless guinea pig skin for 3 weeks with the glycolic acid formulations resulted in approximately a 36–39% decrease in stratum corneum turnover time compared with the control lotion. After this treatment, hairless guinea pigs were sacrificed for the in vitro measurement of the percutaneous absorption of [ 14C]hydroquinone and [ 14C]musk xylol. No significant differences in the 24-hour absorption of either test compound were found for skin treated with the control lotion or the glycolic acid formulations. There were also no significant differences found in the absorption of [ 3H]water through skin from the different treatment groups. Although no increase in skin penetration occurred after treatment with the glycolic acid formulations, histology revealed approximately a twofold increase in epidermal thickness. Also the number of nucleated cell layers nearly doubled in skin treated with 5% and 10% glycolic acid compared with the control lotion and untreated skin. These studies demonstrate that substantial changes in the structure of hairless guinea pig epidermis can occur without significant effect on skin permeability of two model compounds.

Functional Analyses of the Stratum Corneum in Scars

To characterize the functional properties of the stratum corneum (SC) of various scars. A prospective cohort study. University hospital medical center. Thirty-two consecutive patients surgically treated for various skin diseases and 26 consecutive patients with hypertrophic scars or keloids. Noninvasive bioengineering measurements of functional properties of the SC, such as transepidermal water loss (TEWL), high-frequency conductance, and SC turnover time. The SC barrier function assessed by TEWL was found to be a better parameter for the functional evaluation of scars than the hydration state of the skin surface measured by high-frequency conductometry. In general, the SC on the scars of deeper wounds in the dermis took longer to normalize functionally than the SC on the scars of superficial wounds, especially on the high compared with the abdomen. Thus, elevated levels of TEWL observed on scars at the donor sites of split-thickness grafts normalized between 200 and 400 days in contrast to fewer than 50 days for those of subepidermal erosions. Both TEWL and high-frequency conductance remained high in hypertrophic scars and keloids, and the SC involved showed a faster turnover time than that of adjacent normal skin. Scars, a proliferative change of the dermis, can be objectively evaluated according to functional abnormalities of the SC, because the dermis has a close relationship with the epidermis and with the SC. The functional characteristics of the SC of fresh scars and those of hypertrophic scars and keloids resemble those of retinoid-treated skin, rather than those found in epidermal hyperproliferative conditions such as psoriasis and dermatitis.

Effects of calcipotriol on stratum corneum barrier function, hydration and cell renewal in humans

Calcipotriol, a vitamin D analogue utilized for psoriasis, has irritation as its most frequent reported adverse event. However, studies on its irritant properties in humans have produced conflicting data. This study evaluates the effect of calcipotriol on stratum corneum barrier function, hydration and cell turnover in healthy volunteers, compared with sodium lauryl sulphate (SLS) as a model irritant. Calcipotriol 0.005% ointment and 1% aqueous SLS solution were applied for 60 min once daily for 2 weeks (5 consecutive days weekly) on untreated and on dansyl-chloride-labelled skin. Irritant responses were documented by visual scoring and by measurement of the transepidermal water loss (TEWL) and stratum corneum hydration (electrical capacitance), until day 18. Stratum corneum turnover time (SCTT) was the time in days between staining (day 0) and the disappearance of dansyl fluorescence. SLS caused more erythema, scaling, and a significant TEWL increase for 18 days. In contrast, calcipotriol induced erythema, and slightly but significantly increased TEWL on day 11 only, as compared with the vehicle control (P < 0.05). SLS, but not calcipotriol, caused skin dryness from day 4 to day 18. The shortest SCTT was obtained at SLS-exposed sites (11.2 +/- 0.7 days: mean +/- SD). Calcipotriol significantly shortened SCTT (16.3 +/- 1.1 days) when compared with its vehicle. Compared with the skin irritation induced by SLS, under these test conditions, calcipotriol is a far weaker irritant on normal human skin. In addition, calcipotriol accelerates stratum corneum turnover to a significantly greater extent than its vehicle.

Increased stratum corneum turnover induced by subclinical irritant dermatitis

The chronic effects of the irritant sodium lauryl sulphate (SLS) on stratum corneum (SC) barrier function, determined by transepidermal water loss (TEWL) measurements and on epidermal cell kinetics, estimated by stratum corneum turnover time (SCTT) determination (dansyl chloride staining method), were investigated in 18 healthy female volunteers. SLS (7.5%) was applied without occlusion for 20 min once daily, over a period of 3 weeks (5 days a week) on dansyl chloride-stained skin and on untreated skin. SCTT of untreated skin (19.3 +/- 0.8 days; mean +/- SEM) was not changed by daily treatment with water (control) (19.3 +/- 2.0) but was significantly reduced by SLS (10.9 +/- 0.6; P less than or equal to 0.0001; compared to controls). However, TEWL was increased in SLS-treated sites 1.5-fold after 4 days of treatment (5.3 +/- 0.6 vs. 3.5 +/- 0.3; P less than 0.001). At the end of the second week, TEWL was increased 2.6-fold and after 3 weeks TEWL was 3.3 times higher than in controls 13.0 +/- 1.6 vs. 3.9, P less than or equal to 0.0001). The intensity of SLS-induced irritation as measured by TEWL was significantly correlated with baseline TEWL (r = 0.50; P less than or equal to 0.02) and significantly negatively correlated with SCTT of SLS treated sites (r = -50; P less than or equal to 0.02) but not with SCTT of untreated skin (r = 0.19).

Factors Predisposing to Cutaneous Irritation

In experimental skin toxicology, as well as in clinical practice, considerable interindividual variation in the susceptibility to irritant dermatitis is noted when irritant doses are low. Cutaneous sensitivity and hypersensitivity are not determined by a single known feature but are multifactorial. Previous atopic dermatitis may predispose to irritant dermatitis. Susceptibility to irritation seems to be influenced by age, race, and genetic background, whereas sex-related differences do not seem to exist. Of biophysical skin baseline features, skin-surface pH was correlated with the severity of experimentally induced irritant dermatitis, but baseline transepidermal water loss, water-holding capacity, stratum corneum turnover time, and sebum content were not.

加齢に伴う顔面皮膚の生理的，形態的変化 ＩＩ 人種差の検討

Physiological and morphological changes in the facial skin were investigated in relation to aging in British, French, American (caucasian), and Japanese women to clarify racial differences.The following parameters were measured; sebum secretion rate, transepidermal water loss, skin surface conductance, skin surface microtopography, corneocyte surface area, and skin color. In any ethnic group it was shown that sebum secretion rate was highest in the 20's to 30's, after which it declined with aging. However, Japanese women showed most remarkable age-associated change.Transepidermal water loss was inclined to decrease with increasing age and no racial difference was recognized. Skin conductance was low in young age group, and then it increased with aging until 30's or 40's. Caucasian people had higher conductance in every age group examined than Japanese. Skin surface microstructure was considerably changed during the aging process, showing that pore size and irregularity of furrows incresed with aging. From the change in these parameters it was appeared that the skin texture of Japanese women is finer than that of caucasian. British and Japanese women showed almost the same change in corneocyte surface area with aging and so, it was considered that there is little racial difference in the age-related change of turnover time of stratum corneum. It was also found that skin color changes from reddish to yellow and value decreases.

A fluorescence photographic photometric technique to assess stratum corneum turnover rate and barrier function in vivo.

A photographic photometric method for objective measurement of fluorescence in skin is described. This method has been used to (a) improve the dansyl chloride method for determining stratum corneum turnover time by making assessments objective and quantitative, and (b) examine the barrier function of the stratum corneum by measuring the concentration of a fluorescent material at different levels within the stratum corneum at different times.

Accentuation of Ichthyosis Vulgaris in Denervated Skin

A case is reported of accentuation of ichthyotic scales within a localized area of cutaneous denervation in a patient with ichthyosis vulgaris. Determination of stratum corneum turnover time using a fluorescent dye (tetrachlorsalicylanilide) revealed a markedly increased scale adherence in the denervated area suggesting that cutaneous denervation increases epidermal turnover time.