Estimation of sweat rates during cycling exercise by means of the closed chamber condenser technology.

BACKGROUND/AIM: Knowledge of local sweating patterns is of importance in occupational and exercise physiology settings. The recently developed closed chamber condenser technology (Biox Aquaflux® ) allows the measurement of evaporative skin water loss with a greater measurement capacity (up to 1325 g/h/m2 ) compared to traditional evaporimeters. The aim of this study was to evaluate the applicability of the Biox Aquaflux® to estimate sweat production during exercise. METHODS: Fourteen healthy subjects performed a 20-min cycle ergometer trial at respectively 55% heart rate (HRreserve and 75% HRreserve . Sweat production was estimated by measuring body weight before and after exercise, by calculating the amount of sweat collected in a patch, and by measuring the water flux (in g/h/m2 ) with the Biox Aquaflux® instrument. RESULTS: The Biox Aquaflux® instrument allowed the follow up of sweat kinetics at both intensities. Correlations between the measurement methods were all significant for the 75% HRreserve trial (with r ranging from 0.68 to 0.76) whilst for the 55% HRreserve a significant relation was detected between the patch method and the Biox Aquaflux® only (with r ranging from 0.41 to 0.79). CONCLUSION: The Biox Aquaflux® instrument is a practical and direct method for the estimation of local sweat rates under field conditions.

Influence of the timing of ultrasound application on the penetration of corticosteroids.

BACKGROUND: The application of ultrasound to enhance the transdermal transport of drugs is often referred to as 'sonophoresis'. In physiotherapy sonophoresis is applied to the skin through two different procedures: (1) the pre-treatment procedure where the skin is treated with ultrasound irradiation prior to the drug application and (2) a simultaneous treatment mode, where the skin is treated with ultrasound during the application of the pharmacologic substance. The aim of this study was to compare the bioavailability of halcinonide in the stratum corneum comparing the ultrasound pre-treatment vs. the simultaneous treatment method. METHODS: The effect of pre and simultaneous ultrasound treatment (1 MHz, 1 W/cm(2)) was evaluated on the halcinonide blanching response using tristimulus colorimetry 2 h after the initial application. RESULTS: Within the evaluation period, only the ultrasound pre-treatment method resulted in a significant blanching response. CONCLUSION: Timing of the ultrasound application seems to influence the availability and percutaneous penetration process and should be taken into account when estimating the ultrasound enhancing effect.

The influence of stratum corneum hydration on body fat determination by bioelectrical impedance analysis.

BACKGROUND/AIMS: Bioelectrical impedance analysis (BIA) is used for the estimation of the amount of body fat. We evaluated the influence of the stratum corneum hydration at the contact areas used for BIA on the body fat estimation. METHODS: Stratum corneum hydration was measured at the sole of the right foot and the palm of the right hand before and after contact with the Tanita Body Composition Analyzer TBF 410(®) and the Omron Body Fat Analyzer(®) , (n=128 females and 126 males), respectively. Changes in stratum corneum hydration during the contact time were calculated (ΔHYD). As a gold standard for body fat estimation, the underwater weighing method (UWW) was used and the deviation of this standard was calculated for the Tanita (DT) and the Omron (DO) measurement. RESULTS: During contact with the Tanita, stratum corneum hydration increased significantly at the foot. Neither stratum corneum hydration measured at the respective contact sites before BIA nor ΔHYD at the respective skin sites was related to DT or with DO. CONCLUSION: The BIA measuring procedure using the Tanita instrument leads to an occlusive effect at the contact site. BIA for the determination of body composition is not influenced by stratum corneum hydration.

A comparative study of the effects on the skin of a classical bar soap and a syndet cleansing bar in normal use conditions and in the soap chamber test.

BACKGROUND/AIMS: The skin irritation potential of a body cleansing product is often compared under exaggerated test conditions, although the product is intended to be used at home with repetitive and brief contact with the skin. The aim of this study was to determine how much patch testing is predictive of the clinical, sub-clinical and subjective cutaneous effects of products used at home by consumers for their normal hygienic cleansing. METHODS: A double-blind comparative study of the normal use of an alkaline soap bar and a syndet at home during 10 consecutive weeks was performed on two identical groups of 25 healthy female subjects. The eventual skin changes observed at different anatomical skin sites were evaluated by clinical visual examination and by bioengineering measurements before the start of the study and then every 2 weeks. The objective measurements were compared with the subject's perceptions of dryness, tightness and product irritancy during the testing. RESULTS: The bioengineering measurements did not show any significant changes on all the anatomical skin sites, except for a small increase in skin pH with the classical soap bar. However, a trend appeared, showing that the alkaline soap bar is perceived by the subjects themselves as more of an irritant than the syndet bar. In the soap chamber test, the bar soap showed a significantly higher irritancy than the syndet bar. CONCLUSION: This study showed that cutaneous irritation induced by cleansing products in patch testing is not necessarily predictive of the irritation likely to occur in normal use conditions. Finally, a clear relationship could be demonstrated between the results of the soap chamber test and the consumer perception of both cleansing bars.

The Visi-Chroma VC-100: a new imaging colorimeter for dermatocosmetic research.

BACKGROUND/AIMS: It was the aim of this study to carry out a comparative evaluation in vitro on standardized color charts and in vivo on healthy subjects using the Visi-Chroma VC-100, a new imaging tristimulus colorimeter and the Minolta Chromameter CR-200 as a reference instrument. The Visi-Chroma combines tristimulus color analysis with full color visualization of the skin area measured. The technical performances of both instruments were compared with the purpose of validating the use of this new imaging colorimeter in dermatocosmetic research. METHODS: In vitro L*a*b* color parameters were taken with both instruments on standardized color charts (Macbeth and RAL charts) in order to evaluate accuracy, sensitivity range and repeatability. These measurements were completed by in vivo studies on different sites of human skin and studies of color changes induced by topical chemical agents on forearm skin. The accuracy, sensitivity range and repeatability of measurements of selected distances and surfaces in the measuring zone considered and specific color determinations of specific skin zones were also determined. RESULTS: The technical performance of this imaging colorimeter was rather good, with low coefficients of variation for repeatability of in vitro and vivo color measurements. High positive correlations were established in vitro and in vivo over a wide range of color measurements. The imaging colorimeter was able to measure the L*a*b* color parameters of specific chosen parts of the skin area considered and to measure accurately selected distances and surfaces in the same skin site considered. CONCLUSION: These comparative measurements show that both instruments have very similar technical performances and that high levels of correlation were obtained in vitro and in vivo using the L*a*b* color parameters. In addition, the Visi-Chroma presents the following improvements: 1) direct visualization and recording of the skin area considered with concomitant color measurements; 2) determination of the specific color parameters of skin areas chosen in the total measuring area; and 3) accurate determination of selected distances and surfaces in the same skin areas chosen.

Skin color measurements: comparison between three instruments: the Chromameter(R), the DermaSpectrometer(R) and the Mexameter(R).

BACKGROUND/AIMS: Two types of skin reflectance instruments are available nowadays for the determination of skin color: a tristumulus colorimeter (Chromameter from Minolta) using the CIE L*a*b* color system and the narrow-band simple reflectance meters (DermaSpectrometer from Cortex and Mexameter from Courage-Khazaka) using the erythema/melanin indices. The purpose of this study was to compare the capabilities of the three instruments (sensitivity, repeatability and correlation) in vitro and in vivo. METHODS: Comparative color measurements were carried out first in vitro on standardized color charts and subsequently in vivo on different skin areas in human volunteers. Skin color changes induced by various physico-chemical treatments were also quantitatively evaluated with the three instruments. RESULTS: The in vitro and in vivo repeatabilty as well as the sensitivity of the three instruments are rather good. Erythema and skin blanching could be readily quantified by the increase of the a* parameter and of the erythema indices of the simple reflectance meters. Natural UV tanning and artificial chemical tanning could be measured by the decrease of L* and increase of b* and of the melanin indices. CONCLUSION: The Chromameter and the two narrow-band reflectance instruments were able to characterize skin color and to quantify small skin color changes. Moderate to high significant linear correlations could be established between the CIE L*a*b* color parameters and the erythema/melanin indices.

A qualitative estimate of the influence of halcinonide concentration and urea on the reservoir formation in the stratum corneum.

The existence of a stratum corneum reservoir for topically applied substances is well known. Data concerning the stratum corneum retention time are important for the elaboration of optimal topical treatment. We used the re-occlusion technique followed by skin colour measurements (Chromametry) for the evaluation of the stratum corneum retention time of halcinonide. We found a significant reservoir for halcinonide up to 5 days after the initial application. The retention was found to be corticosteroid concentration and formulation dependent.

Evaluation of the preservative properties of Thymus vulgaris essential oil in topically applied formulations under a challenge test.

The preservative properties of thyme essential oil (3%) with a known composition were evaluated in two types of final formulations, suitable for use as pharmaceutical or cosmetic vehicles, by means of a standard challenge test proposed by the latest European Pharmacopoeia. The required preservation efficacy criteria were satisfied against the bacterial strains, against the yeast in one of the formulations, but not against the mould strain involved in this study. Interactions between the essential oil compounds and other factors present in the final formulation might have influenced the activity of this essential oil, leading to an incomplete satisfaction of the criteria.

Influence of temperature on irritation in the hand/forearm immersion test.

As indicated by in vitro experiments the penetration of irritants through the skin is significantly influenced by the temperature of the solution. In vivo experiments, demonstrated equally a significant influence of temperature in surfactant-induced skin irritation. In order to evaluate the irritant potential of detergent solutions under normal user conditions, we used the hand/forearm immersion test. We compared 2 detergents with different anionic character in a repetitive immersion protocol (30 min immersion on 4 consecutive days). The solutions were tested at 2 temperatures (37 degrees C and 40 degrees C). The irritation was quantified by assessment of the stratum corneum barrier function (transepidermal water loss), skin redness (a* colour parameter) and skin dryness (capacitance method). Both detergents affected the integrity of the skin in a significant way. The anionic content as well as the temperature of the solutions were found to be determinative for the irritant potential, with a stronger response for higher anionic content and temperature, respectively.

In vitro calibration of the capacitance method (Corneometer CM 825) and conductance method (Skicon-200) for the evaluation of the hydration state of the skin.

BACKGROUND/AIMS: A major problem with electrical measurements of the capacitance of the skin using the well kwown capacitance method (Corneometer) resides in the fact that the results of this instrument are expressed as arbitrary capacitance hydration units that are not directly related to real electrical units or to the water content of the horny layer. The purpose of this study was to establish a calibration of the capacitance method using a simple in vitro simulation system of the horny layer. METHODS: The calibration of capacitance and conductance methods was carried out using cellulose filter papers saturated with water, aqueous solutions and liquids of different dielectric constant (sorption and desorption experiments). RESULTS: Using this in vitro method, correlations were established between the capacitance values and the quantity of water adsorbed on the filter and with the dielectric constant of the liquid saturating the filter paper. High correlations were observed during sorption and desorption experiments between the capacitance and conductance measurements. CONCLUSIONS: In vitro calibration of the capacitance method is now possible with this simulation model of the horny layer. Furthermore, determination of the range of sensitivity, accuracy, repeatability and depth of detection of the measuring probe of the capacitance and conductance method were carried out.

The effectiveness of massage treatment on cellulite as monitored by ultrasound imaging.

BACKGROUND/AIMS: The visual appearance of cellulite or the'orange peel'look of skin is a common cosmetic problem for many women. Cellulite, or more correctly lipodystrophy, is a modification of the adipose tissue, whereby the fat lobules are swollen as the result of a disturbed blood and lymph micro-circulation and fibrosclerose of connective tissue. In the wealthy diversity of products against cellulite, objective methods to measure their efficacy are of growing importance. The purpose of this study is to establish the effectiveness of a skin massage treatment by quantifying the changes in the skin via ultrasound imaging, during and following treatment. METHODS: Using 20 MHz C-mode ultrasound scanning, a three-dimensional subsurface is constructed that represents the dermis-hypodermis tissue interface. In normal cellulite-free skin, this interface is smooth. In the case of cellulite, however, the dermis-hypodermis junction appears as an irregular surface. Qualitatively, the effect of cellulite treatment is inferred from changes in the shape of this junction. In order to quantify the effect, we chose to monitor the junction area. For the treatments, we used a specially designed handheld electro-mechanical massage device that was moved along the thigh. Treatments were conducted for 3 months, three times a week, during 15 min on each upper leg of 20 healthy female volunteers with moderate symptoms of cellulite (Curri's classification 1-2). Ultrasound measurements were performed monthly, and continued for 2 months after the treatments were stopped. RESULTS: The results, on average, indicate a significant smoothening of the dermis-hypodermis surface (relative surface area reduction 34+3%, 50±3% and 56±2% after 1, 2 and 3 months of treatment, respectively). The smoothening can be described by a mono-exponential function with a time constant of 1.1 month. After the treatments were discontinued, the relative surface area gradually increased (with a time constant of 2.6 month), which indicates that the effect of massage is not permanent. CONCLUSION: Treatment of cellulite by means of an electro-mechanical skin fold massage apparatus significantly smoothens the structure of the dermis-hypodermis interface. Three-dimensional ultrasound imaging of the dermis-hypodermis junction could serve as an objective method to monitor the effectiveness of cellulite treatment.

Does lipid sampling with the Sebutape technique disturb the skin physiology?

BACKGROUND/AIMS: Lipid sampling with the Sebutape technique takes at least 1 h in order to obtain a representative follicular pattern. Subsequent morphometric analysis reveals different parameters on the sebum excretion. However, application of Sebutape may disturb the normal skin physiology, and hence sebum excretion, due to an occlusive effect. The aim of the present study was to evaluate whether collection of skin surface lipids with Sebutape influences skin parameters such as TEWL, skin temperature and stratum corneum hydration. METHODS: On the forehead, a comparison was made between skin sites covered with a Sebutape and contralateral control sites. Prior to removal of the Sebutape, skin temperature under the tape was measured. Immediately after removal of the tape, TEWL and skin capacitance were estimated. The same parameters were determined on the control sites. Furthermore, a comparison was made on the forearms between the occlusion effect of Sebutape application and a complete occlusion with a plastic tape. Hydration of the skin was measured as function of time after removal of both occlusive applications. RESULTS: We detected only a very weak influence of Sebutape application on TEWL and skin hydration. Skin temperature was not affected. A significant difference was detected between the application of Sebutape and the application of a plastic occlusion. CONCLUSIONS: Lipid sampling with Sebutape has only minor or no influence on the skin physiology as demonstrated by TEWL, skin temperature and stratum corneum capacitance measurements.

Study of the stratum corneum barrier function by transepidermal water loss measurements: comparison between two commercial instruments: Evaporimeter and Tewameter.

The measurement of transepidermal water loss (TEWL) is an important noninvasive method in order to assess the barrier function of the stratum corneum. As a consequence, TEWL has been found to be a very useful technique for studying skin irritation induced by various physical and chemical effects. Exposure of the skin to chemicals (detergents) and physical conditions (occlusion and stripping) generally results in an increase of TEWL. Until recently the only commercially available TEWL instrument was the Evaporimeter developed by ServoMed (Sweden). The instrument is based on the open chamber system with two humidity and temperature sensors which measure the water evaporation gradient at the surface of the skin. Recently a new commercially available instrument based on the same physical principle of measurement was developed by Courage and Khazaka (Tewameter, FRG). Our aim in this study has been to compare the measuring capacities of both instruments. The accuracy, sensitivity, variability and reproducibility of both instruments were compared in vivo under identical conditions on normal skin and skin damaged by external conditions. The influence of external and environmental factors such as air and probe temperature, relative humidity, air turbulence and pressure of application was evaluated for both instruments. Finally, the two instruments were compared in practice when following the increase in TEWL of the skin after stripping, occlusion and exposure to irritant household detergents. A very good correlation (r = +0.97) was found between the results of the two instruments over a wide range of TEWL values.

Interactions of rat alpha-foetoprotein with bilirubin.

The binding of bilirubin to rat-alpha-foetoprotein has been measured by changes in the absorption spectrum and by the appearance of two intense circular-dichroism bands. Furthermore binding of this bile pigment has been demonstrated by a decrease of its enzymic oxidation rate and by competition experiments with bovine serum albumin-agarose. The binding parameters have been determined as follows: n = 1.0 mol bound/mol of protein and Ka = 2.9 X 10(6) M-1. Competition of oestradiol for the bilirubin-binding site has not been established.

Rat alpha-foetoprotein. Purification, physicochemical characterization, oestrogen-binding properties and chemical modification of the thiol group.

1. Rat alpha-foetoprotein, an oestrogen-binding foetal globulin, was isolated in large quantities from amniotic fluid and serum by preparative electrophoresis on polyacrylamide slab gels or by chromatography on an immunoadsorbent column. Subsequently the two electrophoretic forms of this protein were separated by electrophoresis on the same medium. 2. Both forms were found to show identical binding with oestradiol. From the extrinsic fluorescence of the bound dye 8-anilinonaphthalene-1-sulphonic acid it was shown that the polarity of the binding site is practically identical for both forms. One residue of tryptophan was determined for both forms. The two electrophoretic variants display the same amount of secondary structure as demonstrated by circular dichroism. 3. The affinity of total alpha-foetoprotein for oestradiol as a function of pH was studied by using a Sephadex G-25 gel-equilibration method. Maximal binding occurred at pH8.5. Only a fractional number of binding sites per molecule could be measured at pH7.4, whereas at higher pH the number of sites was very close to unity. There was no significant effect of pH on the value of the association constant (K(a)=4.3x10(7)+/-1.2x10(7)m(-1)). 4. Displacement experiments of bound labelled oestradiol with various steroids have permitted investigation of the specificity of alpha-foetoprotein. This foetal globulin binds rather strongly compounds that display the rigid structure of the oestratriene skeleton (oestradiol, oestrone). Diminished binding for diethylstilboestrol and a diethylstilboestrol affinity label was observed. No binding was measured with a more flexible structure such as hexoestrol [4,4'-(1,2-diethylethane-1,2-diyl)bisphenol]. 5. Chemical modification of cysteine residues of alpha-foetoprotein with two alkylating reagents [iodoacetic acid and 8-[N-(iodoacetylaminoethyl)amino]naphthalene-1-sulphonic acid] has very little effect on the oestrogen binding. It is suggested that the oestrogen-binding site does not contain a cysteine residue. From the kinetics of alkylation and from the fluorescence properties of the chemically bound thiol reagent 8-[N-(iodoacetylaminoethyl)amino]naphthalene-1-sulphonic acid], it was demonstrated that the very-slow-reacting thiol group is probably located in a non-polar region of the molecule.