Skin colour, skin redness and melanin biometric measurements: comparison study between Antera®3D, Mexameter®and Colorimeter®

In vivo cleansing efficacy of biodegradable exfoliating beads assessed by skin bioengineering techniques

BACKGROUND/PURPOSE

The plastic microbeads, used in many cleansers, will be banned in cosmetic and personal care products within 2017 since they are non-degradable and can disturb the living organisms in water reservoirs. Various choices of biodegradable beads are commercially available, but their efficacy has not been proven yet. This study aimed to compare the cleansing efficacy in dirt and sebum removal aspects of three types of exfoliating beads.

METHODS

The gel scrubs with polyethylene (PE) beads, mannan beads or wax beads, were formulated and evaluated for their stability. The in vivo evaluation was done in 38 healthy volunteers and the skin irritation, efficacy for dirt and sebum removal were measured by Mexameter^® , Colorimeter^® , and Sebumeter^® , respectively.

RESULTS

The selected gel scrubs did not cause an irritation in any volunteers. The differences in dirt residues between before and after scrubbing were not statistically significant among three gel scrubs and the similar result was also reported in the sebum removal study.

CONCLUSION

All gel scrubs demonstrated the comparable cleansing efficacy in term of dirt and sebum removal. Thus, mannan beads and wax beads may be replaced non-biodegradable PE beads to achieve the similar cleansing effect.

Near infrared spectroscopy for body fat sensing in neonates: quantitative analysis by GAMOS simulations

BACKGROUND

Under-nutrition in neonates is closely linked to low body fat percentage. Undernourished neonates are exposed to immediate mortality as well as unwanted health impacts in their later life including obesity and hypertension. One potential low cost approach for obtaining direct measurements of body fat is near-infrared (NIR) interactance. The aims of this study were to model the effect of varying volume fractions of melanin and water in skin over NIR spectra, and to define sensitivity of NIR reflection on changes of thickness of subcutaneous fat. GAMOS simulations were used to develop two single fat layer models and four complete skin models over a range of skin colour (only for four skin models) and hydration within a spectrum of 800-1100 nm. The thickness of the subcutaneous fat was set from 1 to 15 mm in 1 mm intervals in each model.

RESULTS

Varying volume fractions of water in skin resulted minimal changes of NIR intensity at ranges of wavelengths from 890 to 940 nm and from 1010 to 1100 nm. Variation of the melanin volume in skin meanwhile was found to strongly influence the NIR intensity and sensitivity. The NIR sensitivities and NIR intensity over thickness of fat decreased from the Caucasian skin to African skin throughout the range of wavelengths. For the relationship between the NIR reflection and the thickness of subcutaneous fat, logarithmic relationship was obtained.

CONCLUSIONS

The minimal changes of NIR intensity values at wavelengths within the ranges from 890 to 940 nm and from 1010 to 1100 nm to variation of volume fractions of water suggests that wavelengths within those two ranges are considered for use in measurement of body fat to solve the variation of hydration in neonates. The stronger influence of skin colour on NIR shows that the melanin effect needs to be corrected by an independent measurement or by a modeling approach. The logarithmic response obtained with higher sensitivity at the lower range of thickness of fat suggests that implementation of NIRS may be suited for detecting under-nutrition and monitoring nutritional interventions for malnutrition in neonates in resource-constrained communities.

Daily Variation of UV-induced Erythema and the Action of Solar Filters

UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In addition, skin sensitivity shows daily variations, which can interfere in the detection of the efficacy of the filters. Here, we studied the UV-induced erythema in hairless rats at two times of the day (light and darkness) using a colorimeter method. The effect of an emulsion with solar filters with or without melatonin was also assayed. Results indicate that the value of a* (from CIELAB color space values L* a* b) was the most useful variable to evaluate the erythema. However, at the UV intensity used, erythema was only detected when irradiation was carried out during the activity phase of the animal, enabling the detection of the protective action of the sunscreen at this time. Thus, daily variations in skin sensitivity have been demonstrated and should be taken into account in dermatological research.

Comparison of single-spot technique and RGB imaging for erythema index estimation

A commercially available point measurement device, the Mexameter(®), and an experimental RGB imaging prototype device were used for erythema index estimation of 50 rosacea patients by analysing the level of skin redness on the forehead, both cheeks and both sides of a nose. Results are compared with Clinician's Erythema Assessment (CEA) values given by two dermatologists. The Mexameter uses 568 nm and 660 nm LEDs and a photodetector for estimation of erythema index, while the used prototype device acquired RGB images at 460 nm, 530 nm and 665 nm LED illumination. Several erythema index estimation algorithms were compared to determine which one gives the best contrast between increased erythema and normal skin. The erythema index estimations and CEA values correlated much better for the RGB imaging data than for those obtained by the conventional Mexameter technique that is widely used by dermatologists and in clinical trials. In result, we propose an erythema index estimation approach that represents increased erythema with higher accuracy than other available methods.