No abstract

Skin disorders such as atopic dermatitis, psoriasis and senile xerosis show a tendency to exacerbate in winter. We investigated the seasonal influence on the functional parameters of the skin in healthy female volunteers of different age groups. Biophysical noninvasive measurements, including transepidermal water loss (TEWL) as a parameter for the barrier function of the stratum corneum (SC), high-frequency conductance as a parameter for the hydration state of the SC, temperature, color and casual surface lipid levels, were conducted during the later summer and winter months in 39 healthy adult Japanese females ranging in age from 24 to 78 years. The measurements were made on the cheek, the exposed area, and flexor forearm, the semicovered area, in the same climate-controlled chamber. The barrier function of the SC was found to be significantly impaired in winter both on the cheek and flexor forearm. This difference between summer and winter was much larger on the cheek than on the forearm. The hydration state of the SC was significantly lower in winter on the flexor forearm, whereas no such seasonal change was apparent on the cheek where sebum levels did not show any seasonal change. We measured the corneocyte size in 24 out of the 39 subjects to estimate a seasonal change of the turnover rate of the SC. It tended to be smaller only on the exposed cheek skin, suggesting an enhanced turnover of the SC in winter, whereas it was somewhat larger on the semicovered flexor forearm. The skin surface temperature and redness were also significantly higher on the cheek in winter. We think that subclinical inflammation resulted in the enhanced turnover rate of the SC associated with elevated TEWL levels observed on the face in winter. In conclusion, the obtained data suggest that the exposed facial skin becomes more irritable under the influence of the dry and cold environment of winter even in healthy individuals where the barrier function of the SC is relatively poor as compared to the skin of other areas.

Biologic rhythms of cells and organisms are well documented and have been extensively studied at the physiologic and molecular levels. For the skin, many circadian changes have been investigated but few systematic studies comparing skin at different body sites have been reported. In this study we investigated facial and forearm skin circadian rhythms in eight healthy Caucasian women. Noninvasive methods were used to assess skin capacitance, sebum excretion, skin temperature, transepidermal water loss, and skin surface pH on fixed sites of the face and the volar forearm during a 48 h span under standardized environmental conditions. Using the cosinor or ANOVA methods, circadian rhythms could be detected for sebum excretion (face), transepidermal water loss (face and forearm), skin temperature (forearm), pH (face), and capacitance (forearm). No circadian rhythmicity was found for the other biophysical parameters. In addition to the 24 h rhythm component, rhythms with periods of 8 h were found for sebum excretion, of 8 and 12 h for transepidermal water loss (face and forearm), and of 12 h for skin temperature (forearm). Our study confirms that rhythms of skin surface parameters are readily measurable and that these rhythms differ between different sites. Furthermore, we demonstrate for the first time that, for transepidermal water loss (face and forearm), sebum excretion, and skin temperature (forearm), in addition to circadian rhythms, ultradian and/or component rhythms can be detected.

BACKGROUND/AIMS: The aim of this study was to compare the biophysical properties of different facial zones. METHODS: We investigated transepidermal water loss (TEWL), skin temperature and sebum casual level (CL) on 90 adjacent test sites distributed on the forehead, cheeks and chin of five women. RESULTS: All three parameters showed a symmetrical distribution around the facial median line. Only minor variations of individual values were found within the forehead and the chin areas. In contrast, the cheeks exhibited a distinct gradient with highest values in the paranasal zones and lowest on the cheek bones for all of the three parameters. The mean values on both cheeks of a given individual were nearly identical, and the patterns within the two cheeks were superimposable. Both CL and skin temperature distributions pointed out a "T-zone" with highest values on the forehead, on the chin and on the median part of the cheek. CONCLUSIONS: Our data demonstrate that biophysical skin properties differ considerably between different facial areas but that they follow a characteristic distribution.

Background/aims: Understanding structural and functional differences between facial areas is necessary for the formulation of cosmetics and dermatological preparations well tailored to the skin's biophysical characteristics. The objective of the present study was to compare biophysical parameters on malar and frontal facial areas of healthy women classified according to self‐reported cosmetic skin types. Methods: The study population comprised 253 women aged from 20 to 50 years who did not display any signs of dermatological disease. Women declared spontaneously their cosmetic skin type. Skin capacitance, sebum casual level, skin temperature, transepidermal water loss (TEWL), skin colour and relief were assessed on cheeks and forehead in a controlled environment. Results: All biophysical parameters showed statistically significant differences between the two zones. Mean a* chromametric values and TEWL values were significantly higher on cheeks. In contrast, mean b* chromametric values and sebum casual levels showed the highest values on the forehead. Moreover, skin capacitance, temperature, roughness and L.* chromametric value showed minor, while statistically significant, differences between the two zones. With marginal exceptions, the differences between the facial zones for each biophysical parameter remained statistically significant, irrespective of self‐reported skin type. Conclusion: Biophysical parameter mean values differ between frontal and malar zones regardless of self‐reported skin type. Except for the elevated sebum casual levels in “greasy” and “combined” skin, no single or combined biophysical characteristics could be linked to any of the self‐reported skin types. Furthermore our data confirm that in contrast to the common belief that “dry” skin is associated with reduced sebum production, sebum levels in women declaring to have “dry” skin and those declaring to have “normal” skin were not found to be different.