Scientific characterization of subclinical skin changes by noninvasive biophysical methods for development of more efficacious skincare products

In 1966, after finishing only my first year of a residency program, I went to the US to study for 2.5 years with Dr Albert M. Kligman the analysis of functional properties of various skin changes in vivo using aged skin, various types of dermatitis and topically applied steroid-induced atrophy as experimental models. Ten years later, I luckily found that measurements of high frequency conductance and capacitance of the skin enable us to evaluate the skin surface hydration state that determines the softness and smoothness of the skin and in particular to detect even subtle skin changes induced by changes in our environmental or by the application of skincare products and cosmetics. Employing such noninvasive biophysical instruments, I have analyzed the functional properties of normal and abnormal skin changes including subclinical skin changes such as atopic xerosis, senile xerosis, scars and effects of various topical and systemic agents. From these studies it became apparent that as long as a certain level of barrier function was retained skin surface hydration is a more important factor for enjoying a good quality of life. We also succeeded in confirming the effect of corneotherapy, the term so pertinently suggested by Dr Kligman for the beneficial effects of skincare products. We could show that their daily application definitely improves the condition of subclinical skin problems. Further progress in such instrumental analysis of skin properties will greatly aid us in the future in selecting a more desirable skincare product on an individual basis.     

Material design using genetic algorithms and preparation of innovative UV-reflecting composite

The neck is a sun-exposed area. It seems to show the symptoms of photo-ageing as well as facial skin in the elderly. However, the physiological study of neck skin has hardly been reported. We examined the change of skin physiological properties at a neck site with ageing for 61 women (18—69 years old) compared with a cheek site. Water content in stratum corneum (SC) was higher, transepidermal water loss (TEWL) was lower and the turnover rate of SC judged from corneocyte area was slower at the neck site compared with the cheek site. Skin thickness was thinner, skin extensibility and elasticity were higher, skin grooves were deeper, and anisotropy of skin furrows was lower at the neck site than those at the cheek site. It was shown that the neck was also affected by sunlight but not so much as the cheek from the result of gelatinase activity detected in the tape stripped SC. Skin elasticity decreased with ageing at the neck site as well as the cheek site. Fine wrinkles were remarkably increased in the direction of Langer's line with ageing at the neck. Most skin physiological parameters at the neck showed the value between the cheek (heavily sun-exposed area) and back (not sun-exposed area). From these results, it was considered that not only intrinsic ageing but also photo-ageing affected the neck skin. We developed the prototype of cosmetics corresponding to neck skin physiology based on these results, and evaluated the effectiveness of the prototype product by a consumer test including skin measurement for 4 weeks. After treatment, water content increased, and it gave satisfaction in the skin colour brightness, skin elasticity and skin texture improvements for almost all volunteers. It was concluded that the prototype product was useful in neck skin treatment.     

The Skin Blood Supply Factor (SBSF): a useful index for hyperaemia-producing fitness cosmetics

While topical agents cannot really ensure an adequate nutrition of the skin, the natural skin function can at least be stimulated by hyperaemia-producing substances for topical use, which act on the peripheral circulation and thus promote regeneration and nutrition of the skin. In studies involving male and female sports students a given product was applied to the thighs and abdomen. Prior to and 1 h after application skin temperature was measured at accurately defined sites. The quotient computed between the maximum temperatures at treated and untreated test sites was defined to be the Skin Blood Supply Factor. Within the limits of this definition, maximum temperatures of 32.45° C and 32.25° C in treated and untreated skin areas, respectively, give a Skin Blood Supply Factor of 1.04. This is equivalent to a product-induced temperature rise of 4%. Our tests showed that for a physiological effect to be achieved the factor must not be lower than 1.02. In view of peripheral vascular function and considering that product application is virtually unlimited, a factor of 1.08 should not be exceeded. Le facteur d'activation de la circulation sanguine cutanée (SBSF): un indice pour le développement de produits cosmetiques hyperhemiants.     

Connective tissue and aging

Human skin is composed of epidermal and dermal layers, each of which has its own functional importance. Dermis consist of a fine network of collagen fibers, elastic fibers, and other components of the extracellular matrix (ECM). ECM consist primarily of proteins and complex sugars, which form fibrillar networks and a ground substance. Collagen is an important structural component of skin connective tissue and provides the tensile strength of skin. Approximately 70–80% of the dry weight of skin consists of collagen. The most abundant collagen types in skin are types I and III; the former accounts for 80% of the total collagen content of skin and the latter for approximately 15%. The other collagen types present in skin include type IV collagen, which is abundant in the basement membrane (BM); type V collagen, which is located pericellularly; type VI collagen, which plays a role in matrix assembly and is present as microfibrils between collagen fibers; and type VII collagen, which is a structural component of anchoring fibrils. Elastin accounts for only about 1–2% of the dry weight of skin but is important for the maintenance of skin elasticity and resilience. Glycosaminoglycans are of central importance for the maintenance of a water balance in skin, even though the quantities in ECM are small (0.1–0.3% of the dry weight of skin). In the dermis fibroblasts are responsible for the synthesis of ECM proteins. The fibroblasts in the dermis spend majority of time in quiescent state. However in response to activation, the fibroblasts can be reactivated, and certain pool of cell is able to differentiate into myofibroblasts which have important role in repairing skin defects such as during wound healing. During aging the number of fibroblasts is markedly reduced. Also the response of fibroblasts to various growth factors and mechanical or pathological stimulates (wound healing) is diminished. Skin collagen synthesis declines with aging and as the result of such external factors as long‐term sun exposure and medications, for example, topical corticosteroids. In aging skin, collagen fibers become thicker and less soluble and the synthesis of collagen declines. Skin thickness remains quite constant between 20 and 70 years of age, after which a marked decrease in skin thickness occurs. During aging the expression of collagenases are increased and inhibitors of collagenases are reduced leading to increased proteolysis of connective tissue. Recent studies have shown that collagen synthesis is declined in the skin of heavy smokers, while collagenases are increased inducing premature skin aging. The elastic properties of skin are also affected by aging. Along with increasing age, dermal elastic fibers become thicker and fragmented and oxytalan fibers appear fragmented and shortened. Disintegration of elastic fibers is already seen in a minority of fibers between ages 30 and 70, but the changes become more profound after the age of 70 years, affecting a majority of the fibers. As a result of the decreased number of elastic fibers in aged skin, the elastic recovery of skin decreases in elderly people. Even though the content of GAGs and proteoglycans is relatively small, they have significant role in collagen fibril formation, water content of dermis and in mechanical properties. During aging there are marked alterations in different proteoglycans. The amount and synthesis of versican (high molecular size) is decreased and small molecular size decorin is increased. In photoaged skin versican is increased and is closely associated to elastin while decorin is decreased.     

The alkaline pH-adapted skin barrier is disrupted severely by SLS-induced irritation

The pH of the healthy skin is 5.5 and maintained by many regulatory mechanisms. The pH of the skin care product we use on a daily basis can have an influence on the skin properties. To investigate how the physical properties of skin change after the alkaline or acidic pH of the skin care products are applied on the skin for a long term, we adjusted the pH of the skin care products to 3, 5 and 8 (A, B, C), with glycolic acid and triethanolamine. For 5 weeks the skin care products were applied on 20 healthy subjects' ventral forearm and the skin physical properties were measured. After 5 weeks, skin responses to the external stress of 1% (w/v) SLS (sodium lauryl sulphate) irritation and erythema by UV were measured. Skin colour and skin UV response were not altered by the pH. However, on the C-applied site (pH 8) the transepidermal water loss of stratum corneum (SC) increased significantly, the water content increased and desquamation decreased, respectively, and the SLS significantly impaired the skin barrier in comparison with other sites. The alkaline skin care product impaired the skin barrier after repeated application over 5-week period and the skin barrier was disrupted severely by 1% SLS exposure because SC was already impaired by alkaline pH and sensitive to external stress. This suggests that the pH of daily skin care products is very important for skin barrier homeostasis.     

Daily Ingestion of Aloe Vera Gel Powder Containing Aloe Sterols Prevents Skin Photoaging in OVX Hairless Mice

Estrogen deficiencies associated with menopause accelerate spontaneous skin aging and stimulate the ultraviolet (UV) irradiation‐induced photoaging of skin. However, food compositions with the potential to ameliorate the UV irradiation‐induced acceleration of skin aging with menopause have not yet been investigated in detail. In the present study, we examined the ability of plant sterols derived from Aloe vera gel to prevent the UV irradiation‐induced acceleration of skin aging in ovariectomized mice. Skin transepidermal water loss (TEWL) was significantly higher in the ovariectomy group than in the sham operation group following UVB irradiation, whereas skin elasticity was significantly lower. Ultraviolet B (UVB) irradiation induced greater reductions in skin hyaluronic acid levels and more severe collagen fiber damage in the derims in the ovariectomy group than in the sham group. The intake of AVGP significantly ameliorated this acceleration in skin aging by reducing the expression of matrix metalloproteinases (MMPs) and increasing that of epidermal growth factor (EGF) and hyaluronan synthase (HAS) in the skin. These results indicate that AVGP supplementation prevents skin damage induced by UVB irradiation and ovariectomy in part by inhibiting damage to the extracellular matrix.     

Exposure to acute electromagnetic radiation of mobile phone exposure range alters transiently skin homeostasis of a model of pigmented reconstructed epidermis

Exposure to electromagnetic radiations (EMR) produced by mobile phone concerns half the world's population and raises the problem of their impact on human health. In this study, we looked at the effects of mobile phone exposure (GSM basic, 900 MHz, SAR 2 mW g^?1, 6 h) on a model of pigmented skin. We have analysed the expression and localization of various markers of keratinocyte and melanocyte differentiation 2, 6, 18 and 24 h after EMR exposure of reconstructed epidermis containing either only keratinocytes or a combination of keratinocytes and melanocytes grown on dead de‐epidermized dermis, using histology, immunohistochemistry and Western blot. No changes were found in epidermal architecture, localization of epidermal markers, presence of apoptotic cells and the induction of p53 in both types of epidermis (with or without melanocytes) after exposure to EMR. In pigmented reconstructs, no change in the location and dendricity of melanocytes and in melanin transfer to neighbouring keratinocytes was detected after EMR exposure. Loricrin, cytokeratin 14 were significantly decreased at 6 h. The level of all markers increased at 24 h as compared to 6 h post‐EMR exposure, associated with a significant decrease of the 20S proteasome activity. Our data indicate that exposure to 900 MHz frequency induces a transient alteration of epidermal homoeostasis, which may alter the protective capacity of the skin against external factors. Presence or absence of melanocytes did not modify the behaviour of reconstructs after EMR exposure.     

Abatement of the clostridial load in the teats of lactating cows with lysozyme derived from donkey milk

The use of a sterilized product for washing cows' udders before milking may be useful to reduce or prevent Clostridium tyrobutyricum contamination, the main cause of the late-blowing defect in hard and semi-hard cheeses. The aim of this research was to evaluate the antibacterial efficacy of an experimental formula containing 15% condensed donkey milk (lysozyme content 825 mg/L). The antimicrobial activity of condensed milk was first evaluated in vitro, using the disk diffusion method, on the following microorganisms: Bacillus megaterium, Bacillus mojavensis, Clavibacter michiganensis, and Clostridium tyrobutyricum. These results were compared with the effects of 2 antibiotics, ampicillin (100 mg/mL) and kanamycin (50 mg/ mL), and a commercial pre-dipping formula. The results showed that the inhibitory activity of lysozyme from donkey milk on all the considered microorganisms was higher than that of the commercial product and similar to that of the 2 antibiotics. Next, the formula with lysozyme was compared with a commercial pre-dipping formula on 48 lactating cows (24 cows in each group). Skin tests were performed on teats before and after pre-dipping. Results showed that the formula with condensed milk significantly reduced the clostridial load detected on the skin of cows' teats before cleaning (−55.61% vs. −27.99%) and in the bulk milk of the experimental group compared with the control group with commercial product (−52.53% vs. −32.42%).     

Morphological characterization of solar lentigines by in vivo reflectance confocal microscopy: a longitudinal approach

Solar lentigines are benign hyperpigmented skin lesions. Despite their widespread distribution, knowledge on the mechanisms of development is largely unknown. A clinical study was designed in which solar lentigines were characterized using various non‐invasive clinical techniques. A subset of solar lentigines was followed over a 5‐year time period. One hundred and twenty‐eight solar lentigines were evaluated using in vivo reflectance confocal microscopy (RCM) for the evaluation of the length and density of their dermal papillae as well as the deformation of the alignment pattern of hyperrefractive basal cells. Skin colour, colour contrast, the size of the solar lentigo, epidermal proliferation rate, melanin and haemoglobin content were quantified. RCM imaging of solar lentigines revealed a profound structural deformation of the dermal papillae, as the alignment pattern of hyperrefractive basal cells shifted from a circle in non‐lesional skin to an irregular non‐circular shape in solar lentigines. There was a rise in the number of dermal papillae, and these dermal papillae were significantly longer. Solar lentigines had increased melanin and haemoglobin levels and a higher rate of epidermal proliferation. For a subset of nineteen solar lentigines, a longitudinal study was set‐up in which these measurements were repeated 5 years after the first evaluation. The deformation and the number of the hyperrefractive dermal papillary rings increased significantly over the 5‐year time span. The size of the lesion increased, and the skin colour became darker. RCM is a useful non‐invasive clinical tool for the characterization of solar lentigines, in particular the compressive deformation of the dermal papillae. This deformation became more severe over a time period of 5 years. To our knowledge, this is the first time that the in vivo time‐dependent progression of solar lentigines was supported by RCM images, contributing to an improved understanding of the formation and progression of solar lentigines.     

Methodology for Evaluation of Skin Transparency and the Efficacy of an Essence That Can Improve Skin Transparency

Transparency of the skin is an important factor for realizing beautiful skin, but there is only a visual sensory evaluation method by a beauty specialist. It is unclear how skin physiological characteristics can give transparency. Our purpose is to establish an objective method for evaluating the transparency of the skin and to develop a special cosmetics product which can enhance skin transparency, after investigating the mechanism of the skin characteristics which yield transparency. We developed an optical instrument that could independently measure a diffuse reflection as well as a specular reflection by assembling a polarizing filter in a gonio-spectrum photometer. We analyzed the relationship among skin transparency, specular reflection light and diffuse reflection light. It was shown that there was a strong positive correlation between the skin transparency and the intensity of the diffuse reflection light ( r  = 0.699) and no correlation between the skin transparency and the intensity of the specular reflection light ( r  = 0.190). The results of partial least squares (PLS) analysis of the skin transparency and the skin physiological characteristics showed that a highly transparent skin has a fine skin surface texture with a high hydration of stratum corneum, a low melanin content and a low hemoglobin content. On the basis of these results, we developed an essence that can improve skin texture and blood flow, reduce melanin content, and increase the moisture in the stratum corneum. After eight weeks' usage of this product by consumer panels ( n  = 30), it was confirmed that the skin transparency was improved by the increase of the intensity of the diffuse reflection light by gonio-spectrum photometer measurement and by consumers' self-assessment.     

A new makeup remover prepared with a system comprising dual continuous channels (bicontinuous phase) of silicone oil and water

Removing makeup is considered to be the first step in the skincare process. Makeup that has served its purpose is a kind of impurity that should ideally be removed completely to maximize the effects of skincare products applied afterwards. However, the use of silicone resins has significantly improved the long‐lasting property of makeup with the result that makeup can hardly be removed efficiently either with surfactant‐type cleansers like soaps or with oil‐based cleansers like liquid crystalline cleansers. Furthermore, oil‐based makeup removers do not leave the skin feeling fresh but oily, and often have been used in combination with surfactant‐type cleansers. In other words, complete makeup removal and a fresh skin feel are considered to be incompatible in conventional formulation technologies. To obtain compatible systems, we investigated the applicability of a system known as the bicontinuous phase and eventually succeeded in developing a novel system for a makeup remover. This phase can be prepared with a specific composition with a complete hydrophilic‐lipophilic balance in an oil/surfactant/water system by using cyclo‐siloxane, which dissolves silicone resin well. The bicontinuous phase has an oil‐ and water‐continuous microstructure, showing affinity for both aqueous and oily substances. This bicontinuous phase was applied to the development of a novel makeup remover. Determination of remover cap‐ability and fresh skin feel revealed that the makeup could be completely removed and that the amount of oil remaining on skin surface after wash‐off was much less than with previous oil‐based removers. The results of the sensory test also supported the finding that the remover was far superior to conventional products. This makeup remover is the first example of the application of the bicontinuous phase technology to a cosmetic product and clearly seems to provide the best conditions for subsequent skin care, meaning that it is suitable for the first step in the skincare process.     

Evaluation of the efficacy of a topical cosmetic slimming product combining tetrahydroxypropyl ethylenediamine, caffeine, carnitine, forskolin and retinol, In vitro, ex vivo and in vivo studies

Three studies were performed to investigate the mechanism of action and evaluate the efficacy of a topical cosmetic slimming product combining tetrahydroxypropyl ethylenediamine, caffeine, carnitine, forskolin and retinol. The Ex vivo study on skin explants showed that caffeine and forskolin both stimulated glycerol release and demonstrates for the first time that retinol and carnitine in combination synergistically stimulated keratinocyte proliferation, which leads to an increase epidermal thickness. The double-blind, randomized, placebo-controlled clinical study associating circumference measurements on five selected parts of the body, cutaneous hydration measurements as well as blinded expert grading of skin aspect was conducted on 78 women who applied the product or placebo twice daily for 12 consecutive weeks. After 4 weeks of twice-daily application of the product, significant reductions in circumference of abdomen, hips-buttocks and waist were already observed. Improvements concerned all the measured body parts after 12 weeks. Orange peel and stubborn cellulite decreased significantly from 4 weeks of treatment and tonicity improved from 8 weeks, demonstrating that the product improved skin aspect. At the end of the study, eight parameters of the thirteen evaluated were significantly improved in the active group and compared with placebo.     

Evaluation of the efficacy of a dill extract in vitro and in vivo

Lysyl oxidase–like (LOXL) is an extracellular enzyme that catalyses the cross‐linking between microfibrils and tropoelastin (TE), thereby ensuring elastic fibre functionality. With ageing, LOXL expression decreases, thus participating in the loss of skin elasticity. In a previous study, we showed that a dill seed extract [INCI name: Peucedanum graveolens (Dill) extract] could increase LOXL expression in cultured dermal fibroblasts. Besides, we showed a good correlation between the measurements of skin elasticity obtained in vitro and in vivo using a fully automated bio‐tribometer designed to measure the biomechanical properties of soft and complex materials like skin. The aim of this study was to evaluate the ability of the dill extract to improve skin elasticity in vitro and in vivo using different models. Using the bio‐tribometer, we first showed that the lateral elasticity of dermis equivalents (DEs) treated with the dill extract at 1% was significantly increased by +29% (P < 0.01) when compared to untreated DEs. In vivo, skin firmness and elastic recovery measured using cutometry methods were also significantly improved compared to placebo in volunteers treated for 56 days with a formula containing 1% of dill extract. Moreover, the clinical evaluation evidenced significant improvements in ‘skin elasticity’ compared to placebo. A majority of subjects treated with the dill extract also noted significant improvements in skin elasticity, firmness and slackness of the jaw line. Finally, mean wrinkle area and length were also significantly reduced compared to placebo after 84 days as measured using silicone replicas taken from the crow’s feet. In summary, this study showed that the dill extract could improve elasticity of DEs in vitro as well as skin biomechanical properties and appearance in vivo. It also highlights the relevance of using the bio‐tribometer as an exploratory tool for the measurement of skin elasticity in vitro.     

Antioxidant capacity of 3D human skin EpiDermTM model: effects of skin moisturizers

The objective of this study was to determine the effects of skin moisturizers on total antioxidant capacity (TAC) of human skin using EpiDerm^TM model. Three different skin moisturizers containing antioxidant ingredients (samples 1–3) or aloe vera extract were topically applied to EpiDerm^TM units and incubated for 2 and 24 h to determine acute and longer-term effects of applied samples on TAC and glutathione peroxidase activity in medium and/or homogenized skin tissues. Total antioxidant capacity in medium and skin homogenates was enhanced ( P  < 0.0001) by gel containing antioxidant ingredients (sample 2) after 2 and 24 h of incubation. Total antioxidant capacity in medium was also enhanced ( P  < 0.001) by cream containing antioxidant ingredients (sample 3) after 24 h of incubation. Overall, TAC in medium was greater ( P  < 0.02) after 24 h than 2 h of incubation. Skin moisturizer cream with high antioxidant levels determined by using oxygen radical absorbance capacity testing (sample 1) and aloe vera extract did not affect TAC. Glutathione peroxidase activity was enhanced ( P  < 0.0001) in medium and skin homogenates by sample 2 but not by any other sample. These data demonstrate high potential of gel and cream (samples 2 and 3) containing antioxidant ingredients in enhancing antioxidant capacity of EpiDerm^TM which will likely contribute to overall skin health. Results of this experiment will help to better understand mechanisms of effects of skin moisturizers containing antioxidant ingredients on skin function at the tissue level and to establish effective strategies for skin protection and clinical treatments of skin disorders and possibly healing wounds.     

Optical rejuvenating makeup using an innovative shape‐controlled hybrid powder

For women, the sagging of facial skin noticed with ageing is one of the important problems that should be solved. Although conventional skincare cosmetics exist that can prevent sagging, no makeup cosmetics that can correct the appearance of sagging have been developed. The vital factors for an optical rejuvenating makeup were found to be recovery of the skin tension and lightening of the face shadow appearing on sagging skin. Therefore, a hybrid powder consisting of platy barium sulphate on the surface of titanium dioxide-coated mica having red interference light was developed. Results of a panel test showed that almost all panelists noticed the rejuvenating effect of the foundation containing the powder. Image analysis showed that the foundation finish made the face look 12 years younger than the face with no makeup. As the mechanism of the optical rejuvenation, regular reflection of the red interference light from the hybrid powder can give the natural-fresh impression observed for a very young skin, and diffuse reflection of the white light can irradiate the shadow. The development of this innovative shape-controlled hybrid powder offers a new technique for making anti-aging cosmetics. Award winning platform presentation at the IFSCC International Conference 2005, Florence, Italy     

Relating rheological measurements to primary and secondary skin feeling when mineral‐based and Fischer–Tropsch wax‐based cosmetic emulsions and jellies are applied to the skin

Rheology measurements were correlated to skin sensations occurring when cream and petroleum jelly cosmetic products containing different amounts of synthetic Fischer–Tropsch wax were applied to the skin. A panel of 15 people with a background in cosmetic product development were asked to rate skin feelings when a range of petroleum jelly and cream samples are applied to the skin. Primary skin feel, or the spreadability of a cosmetic product, was correlated to the product's flow onset and maximum viscosity as measured by a Anton Paar rheometer, whereas secondary skin feel or the sensation occurring at the end of application when the product was completely rubbed into the skin was correlated to the product's viscosity measured at high shear rates. The cream samples prepared with a petroleum jelly containing 10% and 20% Fischer–Tropsch wax fell within the boundary of good primary skin feeling of cream products. Predominantly, synthetic petroleum jellies were given the best assessments in terms of primary skin feeling and were used with mineral‐based petroleum jellies to determine the boundary of good primary skin feeling for petroleum jelly products. The further away a product falls from this rheological boundary the poorer the skin feeling assessment appears to be by the panel. Products containing Fischer–Tropsch waxes were given the best assessment by the panel for secondary skin feeling. Comments from the panel include that these products feel silky and light on the skin. The higher the Fischer–Tropsch wax content, the lower viscosity was at high shear rate (? = 500 s^?1) and the higher the assessment by the panel. Rheological measurements can be used to objectively determine skin sensation when products are applied to the skin; this may shorten research and development times. A rheology boundary of certain product viscosity and shear stress applied is associated with good primary skin feeling for lotions, creams and petroleum jellies. Lower product viscosity at high shear rate seems to be associated with better secondary skin feeling. Products with higher Fischer–Tropsch wax content appear to be rated higher in terms of secondary skin feeling.     

A look behind the salt curve: the link between rheology, structure, and salt content in shampoo formulations

It has been demonstrated for visual and olfactory stimuli that an increase in heart rate, skin conductance, facial electromyogram activity and breathing rate correlates with negative and/or excited emotional states and a decrease with positive and/or relaxed emotional states. It was the aim of this study to explore the psychophysiological status of emotional moods associated with use of a men's skincare range. Therefore, in a 5-day habituation phase 19 male volunteers (mean age 32 years) used three perfumed products (a shaving mousse, cleansing gel and hydrating cream) for their morning shaving routine and assessed their mood before and after by means of self-assessment manikins and a general mood estimate questionnaire. In a second study phase the psychophysiological parameters heart rate, skin conductance and facial electromyogram activity of the resting subjects were recorded after exposure to three different odors, the fragrance of the men's products of the habituation phase, a control fragrance and the solvent dipropylene glycol. During the habituation phase the cosmetics had positive effects on the mood behavior of the subjects. These positive effects could be confirmed by the objective measurements of peripheral nervous system parameters in the second study phase.     

Topical proteolytic enzymes affect epidermal and dermal properties

Although proteolytic enzymes have a history of use in skin care products it is not known whether they simply induce superficial exfoliation or with continued use can alter epidermal and dermal skin properties. We examined herein whether enhanced exfoliation resulting from treatment with an aspartyl dependent acid protease produces appearance improvements and over time, changes in the epidermis and dermis. Test participants applied 15% enzyme containing serum and a simple moisturizer twice daily for 3 months; a matched control group applied the same serum (without enzyme) and moisturizer. Changes in skin smoothness and texture, the depth and number of lines and wrinkles, and epidermal and dermal firmness and thickness were examined in a double-blind fashion. Treatment with 15% enzyme product(s) resulted in significant improvement in epidermal properties after 1 month and both epidermal and dermal properties after 3 months. The control group showed modest improvements in surface properties only. These results demonstrate that significant appearance benefits can be derived from use of exfoliative proteolytic enzymes. Such improvements are the result of changes to the epidermis and dermis and are strikingly similar to results observed with higher concentrations of AHAs (alpha hydroxy acids).