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Stratum Corneum (stratum + corneum)
Kinds of Stratum Corneum Terms modified by Stratum Corneum Selected AbstractsStratum corneum TARC level is a new indicator of lesional skin inflammation in atopic dermatitisALLERGY, Issue 9 2010E. Morita To cite this article: Morita E, Takahashi H, Niihara H, Dekio I, Sumikawa Y, Murakami Y, Matsunaka H. Stratum corneum TARC level is a new indicator of lesional skin inflammation in atopic dermatitis. Allergy 2010; 65: 1166,1172. Abstract Background:, Management of atopic dermatitis (AD) requires judging the symptoms of local skin lesions and prescribing a suitable treatment. However, no method has been established in which objective measures can be used to evaluate the severity of local symptoms. We established a method for measuring thymus and activation-regulated chemokine (TARC) levels in the stratum corneum (scTARC), and examined whether the scTARC can be used as an indicator of the severity of local skin lesions in patients with AD. Methods:, Stratum corneum was obtained from patients with AD by tape-stripping, and scTARC was evaluated using a TARC-specific antibody followed by image analysis. The scTARC was examined to determine correlation with the severity of local skin lesions (the severity of erythema, edema/papule, oozing/crusts, excoriations, lichenification, and xerosis) as well as with the severity scoring of atopic dermatitis (SCORAD) index, serum TARC level, serum IgE level, serum lactate dehydrogenase (LDH) level, interleukin (IL)-4-producing T cell ratio (Th2 cell ratio), and blood eosinophil count. Results:, The scTARC was correlated with the severity of local skin lesions, especially with the erythema, edema/papule, and oozing/crusts score. The scTARC in the most severe lesions was also correlated with the SCORAD index, serum TARC level, serum IgE level, and blood eosinophil count. The scTARC was not, however, correlated with the serum LDH level and Th2 cell ratio. Conclusion:, An immunofluorescent technique combined with tape-stripping was used to measure scTARC. The scTARC can be used as an indicator of the severity of local acute inflammation in patients with AD. [source] Infant Skin Microstructure Assessed In Vivo Differs from Adult Skin in Organization and at the Cellular LevelPEDIATRIC DERMATOLOGY, Issue 2 2010Georgios N. Stamatas Ph.D. The purpose of this study was to examine infant skin microstructure in vivo and to compare it with that of adult skin. The lower thigh area of 20 healthy mothers (ages 25,43) and their biological children (ages 3,24 months) was examined using in vivo noninvasive methods including fluorescence spectroscopy, video microscopy, and confocal laser scanning microscopy. Stratum corneum and supra-papillary epidermal thickness as well as cell size in the granular layer were assessed from the confocal images. Adhesive tapes were used to remove corneocytes from the outer-most layer of stratum corneum and their size was computed using image analysis. Surface features showed differences in glyph density and surface area. Infant stratum corneum was found to be 30% and infant epidermis 20% thinner than in adults. Infant corneocytes were found to be 20% and granular cells 10% smaller than adult corneocytes indicating a more rapid cell turnover in infants. This observation was confirmed by fluorescence spectroscopy. Dermal papillae density and size distribution also differed. Surprisingly, a distinct direct structural relationship between the stratum corneum morphology and the dermal papillae was observed exclusively in infant skin. A change in reflected signal intensity at ,100 ,m indicating the transition between papillary and reticular dermis was evident only in adult skin. We demonstrate in vivo qualitative and quantitative differences in morphology between infant and adult skin. These differences in skin microstructure may help explain some of the reported functional differences. [source] Synthetic Skin-Permeable Proteins Enabling Needleless Immunization,ANGEWANDTE CHEMIE, Issue 15 2010Yongzhuo Huang Dr. Das geht unter die Haut: Durch die Haut resorbierbare synthetische Antigene wurden erhalten, indem das zellgängige niedermolekulare Protamin (LMWP) über spaltbare Disulfidbrücken an Proteinantigene gebunden wurde. Solche künstlichen Antigene durchdringen das Stratum corneum (siehe Bild) und lösen dadurch eine Antwort des Haut-Immunsystems aus. [source] Polymorphisms in the interleukin-1 gene influence the stratum corneum interleukin-1, concentration in uninvolved skin of patients with chronic irritant contact dermatitisCONTACT DERMATITIS, Issue 5 2008Cindy M. DeJongh Background:, Interleukin (IL)-1, and its receptor antagonist IL-1ra play a role in skin inflammation. Several polymorphisms in the IL1 gene cluster, coding for IL-1,, IL-1ra, and IL-1,, influence their protein expression. Within this cluster, strong linkage disequilibrium has been shown. Objective:, We studied the association between the polymorphisms IL1A -889 (C,T) and IL1B -31 (T,C) and the concentration of IL-1, and IL-1ra in the stratum corneum (SC). Method:, In 124 patients with chronic irritant contact dermatitis, we genotyped the IL1A -889 and IL1B -31 polymorphisms and determined the amount of IL-1, and IL-1ra on tape strips obtained from uninvolved skin of the volar forearm. Results:, The SC IL-1, concentration was 23% and 47% lower in subjects with IL1A -889 C/T genotype and T/T genotype, respectively, compared with wild-type genotype. In subjects with IL1B -31 C/C genotype, the IL-1, concentration was 51% lower compared with C/T and T/T genotypes. The ratio IL-1ra/IL-1, increased twofold in IL1A -889 C/T genotype and threefold in T/T genotype compared with wild type. Conclusions:, We have shown a clear effect of IL1 genotype on protein expression in the SC. This altered expression may be responsible for the interindividual differences in the inflammatory response of the skin. [source] An in vivo model to evaluate the efficacy of barrier creams on the level of skin penetration of chemicalsCONTACT DERMATITIS, Issue 1 2006Alexa Teichmann The reservoir function and the barrier function are important properties of the skin. The reservoir function is dependent on the barrier function which, however, needs support by protective measures, in particular under working conditions. Barrier creams represent a possibility to protect the skin. In the present study, a method was developed to investigate the effectiveness of reservoir closure by different formulations. Patent Blue V in water was used as a model penetrant. Its penetration, with and without barrier cream treatment, was analyzed by tape stripping in combination with UV/VIS spectroscopic measurements. The investigations showed that the stratum corneum represents a reservoir for topically applied Patent Blue V in water. Furthermore, the barrier investigations showed that vaseline and bees wax form a 100% barrier on the skin surface. The third barrier cream, containing waxes and surfactant, only partially showed a protective effect against the penetration of Patent Blue V in water. Strong interindividual differences were observed for this barrier product. In conclusion, it was assumed that the application of barrier creams cannot replace other protective measures and should be maximally used to inhibit low-grade irritants or in combination with other protectants or in body areas where other protective measures are not applicable. [source] The stratum corneum: structure and function in health and diseaseDERMATOLOGIC THERAPY, Issue 2004Clive R. Harding ABSTRACT:, Our understanding of the formation, structure, composition, and maturation of the stratum corneum (SC) has progressed enormously over the past 30 years. Today, there is a growing realization that this structure, while faithfully providing a truly magnificent barrier to water loss, is a unique, intricate biosensor that responds to environmental challenges and surface trauma by initiating a series of biologic processes which rapidly seek to repair the damage and restore barrier homeostasis. The detailed ultrastructural, biochemical, and molecular dissection of the classic "bricks and mortar" model of the SC has provided insights into the basis of dry, scaly skin disorders that range from the cosmetic problems of winter xerosis to severe conditions such as psoriasis. With this knowledge comes the promise of increasingly functional topical therapies. [source] Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansingDERMATOLOGIC THERAPY, Issue 2004K. P. Ananthapadmanabhan ABSTRACT:, Cleanser technology has come a long way from merely cleansing to providing mildness and moisturizing benefits as well. It is known that harsh surfactants in cleansers can cause damage to skin proteins and lipids, leading to after-wash tightness, dryness, barrier damage, irritation, and even itch. In order for cleansers to provide skin-care benefits, they first must minimize surfactant damage to skin proteins and lipids. Secondly, they must deposit and deliver beneficial agents such as occlusives, skin lipids, and humectants under wash conditions to improve skin hydration, as well as mechanical and visual properties. While all surfactants tend to interact to some degree with lipids, their interaction with proteins can vary significantly, depending upon the nature of their functional head group. In vitro, ex vivo, and in vivo studies have shown that surfactants that cause significant skin irritation interact strongly with skin proteins. Based on this understanding, several surfactants and surfactant mixtures have been identified as "less irritating" mild surfactants because of their diminished interactions with skin proteins. Surfactants that interact minimally with both skin lipids and proteins are especially mild. Another factor that can aggravate surfactant-induced dryness and irritation is the pH of the cleanser. The present authors' recent studies demonstrate that high pH (pH 10) solutions, even in the absence of surfactants, can increase stratum corneum (SC) swelling and alter lipid rigidity, thereby suggesting that cleansers with neutral or acidic pH, close to SC-normal pH 5.5, may be potentially less damaging to the skin. Mildness enhancers and moisturizing agents such as lipids, occlusives, and humectants minimize damaging interactions between surfactants, and skin proteins and lipids, and thereby, reduce skin damage. In addition, these agents play an ameliorative role, replenishing the skin lipids lost during the wash period. The present review discusses the benefits of such agents and their respective roles in improving the overall health of the skin barrier. [source] Embryonic keratinization in vertebrates in relation to land colonizationACTA ZOOLOGICA, Issue 1 2009L. Alibardi Abstract The embryogenesis and cytology of the epidermis in different vertebrates is variable in relation to the formation of a stratum corneum of different complexity. The latter process was essential for land colonization during vertebrate evolution and produced an efficient barrier in amniotes. Keratinocytes are made of cross-linked keratins associated with specific proteins and lipids that are produced at advanced stages of embryogenesis when the epidermis becomes stratified. In these stages the epidermis changes from an aquatic to a terrestrial type, preadapted in preparation for the impact with the dry terrestrial environment that occurs at hatching or parturition. The epidermal barrier against water-loss, mechanical and chemical stress, and microbe penetration is completely formed shortly before birth. Beneath the outer periderm, variably stratified embryonic layers containing glycine-rich alpha-keratins are formed in preparation for adult life. The following layers of the epidermis produce proteins for the formation of the cornified cell membrane and of the cornified material present in keratinocytes of the adult epidermis in reptiles, birds and mammals. The general features of the process of soft cornification in the embryonic epidermis of vertebrates are presented. Cornification in developing scales in reptiles, avian feathers and mammalian hairs is mainly related to the evolution of keratin-associated proteins. The latter proteins form the resistant matrix of hard skin derivatives such as claws, beaks, nails and horns. [source] Differential expression of antimicrobial peptides in margins of chronic woundsEXPERIMENTAL DERMATOLOGY, Issue 7 2010Stefanie Dressel Please cite this paper as: Differential expression of antimicrobial peptides in margins of chronic wounds. Experimental Dermatology 2010; 19: 628,632. Abstract:, Skin wounds usually heal without major infections, although the loss of the mechanical epithelial barrier exposes the tissue to various bacteria. One reason may be the expression of antimicrobial peptides (AMP) of which some [human ,-defensins (hBD) and LL-37] were recently shown to support additionally certain steps of wound healing. There are no studies which have compared expression patterns of different classes of AMP in chronic wounds. The aim of our study was therefore to analyse the expression profile of hBD-2, hBD-3, LL-37, psoriasin and RNase 7 by immunohistochemistry from defined wound margins of chronic venous ulcers. We detected a strong induction of psoriasin and hBD-2 in chronic wounds in comparison with healthy skin. Except for stratum corneum, no expression of RNase 7 and LL-37 was detected in the epidermis while expression of hBD-3 was heterogeneous. Bacterial swabs identified Staphylococcus aureus and additional bacterial populations, but no association between colonization and AMP expression was found. The differential expression of AMP is noteworthy considering the high bacterial load of chronic ulcers. Clinically, supplementation of AMP with the capability to enhance wound healing besides restricting bacterial overgrowth could present a physiological support for treatment of disturbed wound healing. [source] Functional skin adaptation in infancy , almost complete but not fully competentEXPERIMENTAL DERMATOLOGY, Issue 6 2010Joachim W. Fluhr Please cite this paper as: Functional skin adaptation in infancy , almost complete but not fully competent. Experimental Dermatology 2010; 19: 483,492. Abstract:, Early postnatal life is a period of active functional reorganization and cutaneous physiological adaptation to the extrauterine environment. Skin as the outermost organ of mammalians is endowed of multiple functions such as protection, secretion, absorption and thermoregulation. Birth stimulates the epidermal barrier maturation and the skin surface acidification especially in premature infants. In full-term infants the developed stratum corneum accomplishes competent barrier function, in contrast to prematures. Complete barrier maturation in preterm infants is fulfilled by 2,4 weeks of the postnatal life. However, in preterms with 23,25 weeks gestational age this process takes longer. Versatile regulatory mechanisms, namely skin surface acidity, calcium ion gradient and nuclear hormone receptors/ligands are interrelated in the complex postnatal newborn adaptation. The skin of newborns is adjusting quickly to the challenging environmental conditions of the postpartum. However, certain functions, for example, microcirculation, continue to develop even beyond the neonatal period, that is, up to the age of 14,17 weeks. Different environmental factors (for instance, dry and cold climate, diapers and cosmetic care procedures) influence the postnatal development of skin functional parameters such as stratum corneum hydration and the permeability barrier especially in premature infants. The aim of this article is to summarize the current knowledge on skin physiology in newborn and infants with a practical approach and to discuss the possible clinical consequences. This review offers the readership a critical and practical overview of skin physiology in newborns and infants. It emphasizes possible new research fields in neonatal and infantile skin physiology. [source] Sodium lauryl sulphate alters the mRNA expression of lipid-metabolizing enzymes and PPAR signalling in normal human skin in vivoEXPERIMENTAL DERMATOLOGY, Issue 12 2009Hans Törmä Abstract:, Detergents irritate skin and affect skin barrier homeostasis. In this study, healthy skin was exposed to 1% sodium lauryl sulphate (SLS) in water for 24 h. Biopsies were taken 6 h to 8 days post exposure. Lipid patterns were stained in situ and real-time polymerase chain reaction (PCR) was used to examine mRNA expression of enzymes synthesizing barrier lipids, peroxisome proliferator-activated receptors (PPAR) and lipoxygenases. The lipid pattern was disorganized from 6 h to 3 days after SLS exposure. Concomitant changes in mRNA expression included: (i) reduction, followed by induction, of ceramide-generating ,-glucocerebrosidase, (ii) increase on day 1 of two other enzymes for ceramide biosynthesis and (iii) persistent reduction of acetyl-CoA carboxylase-B, a key enzyme in fatty acid synthesis. Surprisingly, the rate-limiting enzyme in cholesterol synthesis, HMG-CoA reductase, was unaltered. Among putative regulators of barrier lipids synthesis, PPAR, and PPAR, exhibited reduced mRNA expression, while PPAR,/, and LXR, were unaltered. Epidermal lipoxygenase-3, which may generate PPAR, agonists, exhibited reduced expression. In conclusion, SLS induces reorganization of lipids in the stratum corneum, which play a role in detergents' destruction of the barrier. The changes in mRNA expression of enzymes involved in synthesizing barrier lipids are probably important for the restoration of the barrier. [source] Influence of calcium on the proteolytic degradation of the calmodulin-like skin protein (calmodulin-like protein 5) in psoriatic epidermisEXPERIMENTAL DERMATOLOGY, Issue 6 2006Bruno Méhul Abstract:, The calmodulin-like skin protein (CLSP) or so-called calmodulin-like protein 5, a recently discovered skin-specific calcium-binding protein, is closely related to keratinocyte differentiation. The 16-kDa protein is proteolytically degraded in the upper layers of the stratum corneum (SC) of healthy skin. With the use of specific new monoclonal antibodies to CLSP, we were able to demonstrate that the abnormal elevated levels of CLSP, characteristic of psoriatic epidermis, were probably not due to an overexpression of the protein, but most likely the result of its non-degradation. Further in vitro experiments using recombinant CLSP and in situ data clearly showed that calcium protected and chelator accelerated CLSP degradation. These data indicate that CLSP degradation in the SC of psoriatic skin might be hindered by the abnormally elevated calcium concentration. No degradation of CLSP in psoriatic epidermis keeping its ability to bind protein as transglutaminase 3 may have a physiological role in skin diseases such as psoriasis. [source] Defining the caspase-containing apoptotic machinery contributing to cornification in human epidermal equivalentsEXPERIMENTAL DERMATOLOGY, Issue 1 2006Vijaya Chaturvedi Abstract:, Whether terminal differentiation/stratum corneum formation of keratinocytes (KCs) represents a form of programmed cell death, utilizing mediators of classical apoptosis, is unclear. Apoptosis, an evolutionarily conserved death process, is comprised of extrinsic and intrinsic pathways, which converge using caspase 3. To define upstream and downstream caspases involved in terminal differentiation, we utilized human epidermal equivalents (EEs). Using submerged cultures comprised of human KCs, EEs were sequentially analyzed before and after being raised to an air/liquid (A/L) interface at 3,24 h intervals. At each time point, EEs were analyzed morphologically and for specific enzyme activity to distinguish different initiator (caspases 1, 2, 8, 9) and effector caspases (3, 6, 7). Terminal differentiation began at 6,8 h, as defined by stratum corneum with loricirin expression and completed at 18,24 h producing an epidermis resembling normal skin. Enzyme activity for caspases 1, 2, 3, 6, 7, 8, and 9 (but not 4, 5) was enhanced (>two-fold nmol/mg/h) at 3,6 h compared with submerged cultures. Processing of caspase 14 occurred at 18 h, and cleaved caspase 14 was increased at 24 h. Activated caspase 3-positive and terminal deoxynucleotidyl transferase-mediated nick end labeling-positive KCs were identified in EEs at 3,6 h corresponding to initiation sites of terminal differentiation. Addition of caspase inhibitors reduced levels of involucrin and loricrin in EEs raised to an A/L interface. We conclude caspases function as important death effectors strategically positioned at intersection of intrinsic and extrinsic pathways in KCs undergoing stratum corneum formation. [source] Electrode design for skin electroporation with minimal nerve stimulationEXPERIMENTAL DERMATOLOGY, Issue 9 2004U. Pliquett Electroporation is an efficient tool for transdermal delivery of water-soluble molecules sizing up to several kDa. The main barrier to these agents is the stratum corneum, a 15 mm thin layer of dead keratinized cells. Once this layer is charged (approximately 50 V) by an outer electric field, structural rearrangements of the lipids create aqueous pathways (electroporation). Due to the high electric field within the stratum corneum, (E = 50 V/15 µm = 33 kV/cm) electrophoresis can drive charged molecules into the deeper skin layers. A major concern is the high electric field required, because nerve stimulation is inconvenient for the patient. Taking advantage of the fact that up to a depth of 50 µm no nervous receptors appear, a confinement of the field within the upper 15 µm would circumvent sensation. Field confinement within the stratum corneum is arranged by a special electrode geometry, an array of 300 µm holes within a 0.5 mm thick dielectric. The bottom, facing the stratum corneum, is metalized with a gap to the holes. The size of this gap (3,10 µm) is critical for the penetration depth of the electric field between the metalized bottom and a distant electrode at the other side of the holes. A drug reservoir is implemented below the distant electrode and the dielectric. [source] Carbohydrate expression and modification during keratinocyte differentiation in normal human and reconstructed epidermisEXPERIMENTAL DERMATOLOGY, Issue 5 2003Bruno Méhul Abstract:, Using fluorescein isothiocyanate (FITC)-labeled lectins we were able to demonstrate the presence of specific carbohydrate moieties in normal human and reconstructed epidermis. Evidence is provided that in both cases the strongly reduced lectin staining at the level of the stratum corneum is the result of a hindered accessibility of the lectins in this lipid-rich hydrophobic environment. Isolated corneocytes and purified cornified envelopes (CEs) exhibited clearly glycosylated structures reacting with distinct lectins. The presence of glycosidase activity, particularly in the upper layers of the epidermis characterized by an acidic environment (pH 5.5), indicates that modifications of the sugar residues might be important in epidermal homeostasis, barrier behavior and desquamation. Absent or strongly reduced glycosidase activity in the stratum corneum of reconstructed epidermis with an impaired pH gradient could be in part responsible for the reduced barrier function and the lack of desquamation in this model. [source] Effect of the lactic acid bacterium Streptococcus thermophilus on stratum corneum ceramide levels and signs and symptoms of atopic dermatitis patientsEXPERIMENTAL DERMATOLOGY, Issue 5 2003Luisa Di Marzio Abstract:, A reduced amount of total ceramides could be responsible for functional abnormalities of the skin of atopic dermatitis (AD) patients. The ability of an experimental cream containing sonicated Streptococcus thermophilus to increase skin ceramide levels in healthy subjects has been previously reported. The aim of the present work was to investigate the effects of the topical administration of a S. thermophilus -containing cream on ceramide levels of stratum corneum from AD patients. A 2-week application of the cream, containing a sonicated preparation of the lactic acid bacterium S. thermophilus, in the forearm skin of 11 patients led to a significant and relevant increase of skin ceramide amounts, which could have resulted from the sphingomyelin hydrolysis through the bacterial sphingomyelinase. Moreover, in all patients the topical application of our experimental cream also resulted in the improvement of the signs and symptoms characteristic of AD skin (i.e. erythema, scaling, pruritus). [source] Identification of a novel mutation in keratin 1 in a family with epidermolytic hyperkeratosisEXPERIMENTAL DERMATOLOGY, Issue 1 2000M. J. Arin Abstract: Epidermolytic hyperkeratosis (EHK) is a hereditary skin disorder typified by blistering due to cytolysis. One in 100,000 individuals is affected by this autosomal-dominant disease. The onset of the disease phenotype is typically at birth. Histological and ultrastructural examination of the epidermis shows a thickened stratum corneum and tonofilament clumping around the nucleus of suprabasal keratinocytes. Linkage studies localized the disease genes on chromosomes 12q and 17q which contain the type II and type I keratin gene clusters. Recently, several point mutations in the genes encoding the suprabasal keratins, K1 and K10, have been reported in EHK patients. We have investigated a large kindred affected by EHK and identified a new point mutation in the 2B region of keratin 1 (I107T), resulting from a T to C transition in codon 478. [source] Epicutaneous immunization converts subsequent and established antigen-specific T helper type 1 (Th1) to Th2-type responsesIMMUNOLOGY, Issue 1 2006Jessica Strid Summary Epicutaneous immunization is a potential novel technique for topical vaccine delivery. It targets the immunologically rich milieu of the skin while having the advantage of being a non-invasive immunization procedure. By disrupting the stratum corneum of the epidermis a natural adjuvant effect can be achieved through activation of resident Langerhans cells. This negates the normal need for co-application of noxious adjuvants. Epicutaneous immunization on barrier-disrupted skin induces potent antigen-specific systemic immunity with a strong T helper type 2 (Th2) bias. We show here that epicutaneous immunization enhances the vigour of a subsequent T-cell response to the same antigen. The induced systemic Th2 response prevents the development of Th1 responses induced through injection of antigen in complete Freund's adjuvant (CFA). Prior epicutaneous immunization results in reduced production of antigen-specific interferon-, and immunoglobulin G2a (IgG2a) and enhanced interleukin-4, IgG1 and IgE responses to immunization with CFA. Moreover, epicutaneous immunization converts an established Th1 response to a Th2 response, as demonstrated by the specific reduction of interferon-, and IgG2a and the enhancement of interleukin-4 and IgE. This Th2 dominance of epicutaneous immunization may have direct therapeutic application as an immune-modulating procedure in Th1-dominant diseases such as autoimmune rheumatoid arthritis, type 1 diabetes, Hashimoto's thyroiditis and multiple sclerosis. [source] Abstracts: The effects of licorice leaf extract on ceramide and hyaluronan synthesisINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2010Akinori Kiso pp.267,273 Both water-holding and permeability barrier function in the stratum corneum (SC) are essential for keeping skin moisture. Intercellular lipids in SC, which are composed mainly of cholesterol, fatty acids, and ceramides, play a crucial role for maintaining the function in SC. The object of our study is to find active ingredients from plant extracts for enhancing the abilities of skin hydration and barrier repair by focusing on the synthesis of ceramides. As a result, we found that licorice leaf extract is a promising ingredient showing not only an increase of mRNA expression levels of serine palmytoyltransferase (SPT) and sphingomyelinase related to ceramide biosynthesis in keratinocytes but also syntheses of ceramides in a 3D skin model and in human skin. Furthermore, licorice leaf extract showed an increase of mRNA expression levels of HMG-CoA reductase (HMGCR) related to cholesterol biosynthesis and an increase of hyaluronan (HA) production in in vitro tests. One of the principles isolated from licorice leaf extract, 6-prenyl-naringenin, was thought to be one of the active components. These results suggested that licorice leaf extract may be a useful ingredient for skin care due to the synthesis of intercellular lipids and HA [source] Location-related differences in structure and function of the stratum corneum with special emphasis on those of the facial skinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2008H. Tagami Synopsis Between the two different kinds of the skin covering the body, the glabrous skin is found only on the palmo-plantar surface because of its rather simple function to protect the underlying living tissue with its remarkably thick stratum corneum (SC) from strong external force and friction. Thus, its barrier function is extremely poor. In contrast, the hair-bearing skin covers almost all over the body surface regardless of the presence of long hair or vellus hair. In regard to its SC, many dermatologists and skin scientists think that it is too thin to show any site-specific differences, because the SC is just present as an efficient barrier membrane to protect our body from desiccation as well as against the invasion by external injurious agents. However, there are remarkable regional differences not only in the living skin tissue but also even in such thin SC reflecting the function of each anatomical location. These differences in the SC have been mostly disclosed with the advent of non-invasive biophysical instruments, particularly the one that enables us to measure transepidermal water loss (TEWL), the parameter of the SC barrier function, and the one that evaluates the hydration state of the skin surface, the parameter of the water-holding capacity of the SC that brings about softness and smoothness to the skin surface. These in vivo instrumental measurements of the SC have disclosed the presence of remarkable differences in the functional properties of the SC particularly between the face and other portions of the body. The SC of the facial skin is thinner, being composed of smaller layers of corneocytes than that of the trunk and limbs. It shows unique functional characteristics to provide hydrated skin surface but relatively poor barrier function, which is similar to that observed in retinoid-treated skin or to that of fresh scar or keloidal scars. Moreover, there even exist unexpected, site-dependent differences in the SC of the facial skin such as the forehead, eyelid, cheek, nose and perioral regions, although each location occupies only a small area. Between these locations, the cheek shows the lowest TEWL in contrast to the perioral region that reveals the highest one. Moreover, these features are not static but change with age particularly between children and adults and maybe also between genders. Among various facial locations, the eyelid skin is distinct from others because its SC is associated with poor skin surface lipids and a thin SC cell layer composed of large corneocytes that brings about high surface hydration state but poor barrier function, whereas the vermillion borders of the lips that are covered by an exposed part of the oral mucosa exhibit remarkably poor barrier function and low hydration state. Future studies aiming at the establishment of the functional mapping in each facial region and in other body regions will shed light on more delicate site-dependent differences, which will provide us important information in planning the strategy to start so called tailor-made skin care for each location of the body. Résumé Entre les deux types différents de peau couvrant le crops, on trouve la peau glabre uniquement sur la surface palmo-plantaire du fait de sa fonction plutôt simple de protection du tissu vivant sous-jacent par un stratum corneum (SC) trés épais vis-à-vis des forces extérieures et de la friction. De ce fait, sa fonction barrière est extrêmement pauvre. Au contraire, la peau velue courve la presque totalité de la surface du crops, que ce soit par la présence de longs cheveux ou de duvet. En ce qui concerne son SC, la plupart des dermatologues et des scientifiques de la peau pensent qu'il est trop mince pour montrer une différence spécifique au site, attendu que le SC est simplement présent en tant que membrane barriére efficace pour protéger notre corps de la dessiccation ainsi que pour lutter contre l'invasion d'agents nuisibles externes. Cependant, il existe des différences importantes entre les sites, non seulement dans la peau vivante, mais également dans ce SC aussi mince, qui révèlent la fonctin de chaque site anatomique. Ces différences dans le SC ont surtout été révélées avec l'apparition d'instruments biophysiques non invasifs, en particulier celui qui nous permet de mesurer la perte transépidermale en eau (TEWL), le paramétre de la fonction barrière du SC et celui qui évalue l'état d'hydratation de la surface de peau, le paramètre de la capacité en rétention de l'eau du SC qui est liéà la souplesse et à la douceur à la surface de peau. Ces mesures instrumentales in vivo du SC ont révélé la présence de différences remarquables entre les propriétés fonctionnelles du SC particulièrement entre le visage et d'autres parties du corps. Le SC de la peau de la face est plus mince, car li est composé de couches plus petites de corneocytes que celui du tronc et des membres. Il montre des caractéristiques fonctionnelles uniques pour permettre l'hydratation de la surface de peau, mais une fonction barrière relativement faible, semblable à celle observée dans la peau traitée avec un rétinoïde ou à celle d'une cicatrice récente ou de cicatrices kéloidales. De plus, il existe des différences sites-dépendantes inattendues dans le SC de la peau de la face comme le front, la paupière, la joue, le nez et les régions périorales, et ce, bien que chaque emplacement occupe seulement un petit secteur. Entre ces divers emplacements, la joue montre le TEWL le plus bas par comparaison avec la région périorale qui montre le plus élevé. De plus, ces caractéristiques ne sont pas fixes, mais changent avec l'âge en particulier entre enfants et adultes et peut-être aussi entre sexes. Entre les diverses régions de la face, la peau de la paupière se distingue parce que son SC est associéà une peau pauvre en lipides de surface constituée par une mince couche de cellule composée de grand cornéocytes qui provoquent un haut état d'hydratation superficiel, mais une faible fonction barrière. A l'inverse les bordures vermillion des lévres recouvertes par une partie exposée de muqueuse orale, possèdent une fonction barrière très faible et un état d'hydratation bas. Les études futures visant àétablir la configuration fonctionnelle de chaque région de la face et d'autres régions du corps mettrons en lumière des différences sites-dépendantes plus subtiles, qui nous fourniront des informations importantes pour planifier la stratégie pour commencer le soin de la peau sur mesure si attendu pour chaque partie du corps. [source] In vitro evaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric techniqueINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2008M. D. Bleasel Synopsis A method for the in vitro determination of low- and high-value sun protection factors (SPF) of sunscreens using artificial substrates and a novel pseudo double beam (PDB) mode of operation of a standard double beam UV spectrophotometer is described. The method allows transmittance to be calculated from detector responses of reference and sample beams measured at different gain levels and facilitates the accurate quantification of low levels of electromagnetic radiation transmitted through highly absorbing samples. The spectrophotometer was modified to hold quartz diffusing plates on which a substrate [TransporeÔ adhesive tape or human stratum corneum obtained from a skin surface biopsy (SSB)] and the sunscreens to be tested were applied. The PDB mode of operation increased the effective linear range of the detector response of the spectrophotometer by a factor of approximately 20000-fold, enabling the in vitro SPF determination technique to be applied to both high and low SPF value sunscreens. Eight commercial sunscreens with known SPF values ranging from 4 to 77, previously determined by in vivo methods, were tested in vitro using both test substrates and correlations between the in vivo and in vitro values were determined. SPF values determined using the in vitro method correlated well with the known in vivo results (TransporeÔ tape, R2 = 0.611; SSB, R2 = 0.7928). The in vitro SPF obtained for one of the tested products differed substantially from the cited in vivo SPF value. Independent in vitro and in vivo re-evaluation of the SPF of this product matched the value predicted by the present method much more closely than the originally cited in vivo value. All determined SPFs were ordered correctly in comparison to in vivo ranking and the technique appeared to correctly identify a sunscreen that had a labelled SPF value that was significantly higher than its true SPF. Résumé Une méthode destinée à déterminer in vitro les facteurs de protection solaire (SPF) d'écrans solaires de faible et haut indice est décrite. Elle met en ,uvre des substrats artificiels et un nouveau mode opératoire reposant sur l'utilisation du pseudo double faisceau (PDB) d'un spectrophotomètre UV double faisceau standard. La méthode permet le calcul de la transmittence à partir des réponses du détecteur de référence et la mesure en simple faisceau à différents niveaux de gain facilitant ainsi la quantification précise des faibles niveaux de radiation électromagnétique (EMR) transmis à travers des échantillons hautement absorbants. Le spectrophotomètre a été modifié de façon à fixer des plaques diffusantes en quartz sur lesquelles un substrat (ruban adhésif Transport TM ou du stratum corneum humain obtenu à partir de biopsie de surface de peau (SSB) et les écrans solaires testés ont été appliqués. Le mode opératoire PTB augmente la gamme linéaire effective de la réponse du détecteur du spectrophotomètre d'un facteur approximatif 20.000 permettant, à cette technique de détermination des SPF in vitro, d'être appliquée à la fois sur les écrans solaires de haut et bas SPF. Huit écrans solaires commerciaux de SPF connus allant de 4 à 77, préalablement déterminés par des méthodes in vivo, ont été testés in vitro en utilisant les deux substrats, et les corrélations entre les valeurs in vivo et in vitro ont été déterminées. Les valeurs SPF déterminées en utilisant la méthode in vitro est bien corrélée avec les résultats in vivo connus (ruban transport, R2 = 0.611; SSB, R2 = .7928). Le SPF in vitro pour l'un des produits testés diffère fortement des valeurs SPF citées in vivo. Une réévaluation indépendante des SPF in vitro et in vivo de ce produit ajuste la valeur prédite par la présente méthode de façon beaucoup plus proche que la valeur originale citée in vivo. Tous les SPF ainsi déterminés sont ordonnés correctement en comparaison au classement in vivo et la technique semble identifier correctement un écran solaire qui possède un SPF libellé significativement plus haut que son vrai SPF. [source] Use of associating polymers as multifunctional thickeners: studies of Their structure in aqueous solutions via nmr, qels, fluorescence, And rheology measurementsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2007Katsunori Yoshida The solution properties of an associating polymer were studied by NMR, quasi-elastic light scattering (QELS), fluorescence, and rheology measurements. An associative thickening (AT) polymer was designed having a nonionic poly(ethylene oxide) backbone with long alkyl chains at both ends to achieve high viscosity even at relatively high salt concentrations and over a wide pH range. This study focuses on the associative state of the polymer in aqueous solutions at various polymer concentrations. In a fluorescence probe study using pyrene a spectral change in the I3/I1 ratio was observed for pyrene at a polymer concentration (Cp) of 3 x 10 -4%, indicating an apparent critical concentration (cmc) of the amphiphilic polymer. The viscosity, self-diffusion coefficient (Dsel), and hydrodynamic size (Rh) distribution measurements at various Cp all suggest that there is a second transition at Cp, 0.4%. Although we observed the discontinuity in viscosity, Dsel, and Rh at Cp, 0.4%, no changes in the relaxation times (T1 and T2) were recognized for either the alkyl chain or the ethylene oxide moiety of the polymer at C p= 0.1,1%. These data suggest that there are no structural changes or phase transitions at Cp, 0.4%, but that intermicellar networks are presumably formed by bridging of the end alkyl groups of the polymer, which is driven by hydrophobic forces. Because the polymer forms networks by hydrophobic interaction and the polymer itself is nonionic, the viscosity of the polymer solution was influenced very little by either the addition of salt or a pH change, as would be expected. The dynamic viscoelastic study revealed that the polymer solution exhibits a single mode Maxwell type relaxation behavior with a terminal relaxation time of about 0.61 s, which imparts a unique flow appearance to the polymer solutions. The time course measurements of the dynamic elastic modulus of the stratum corneum revealed that the polymer has excellent potential for skin softening. It was concluded that the associative thickening polymer not only is a useful thickener with a salt and pH tolerance but also has beneficial skincare effects. [source] Is the axilla a distinct skin phenotype?INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2007A. Watkinson The axillary skin is cosmetically important with millions of consumers daily applying antiperspirant/deodorant products. Despite this, we know virtually nothing about axillary skin or how antiperspirant use impacts upon it. To characterize axillary stratum corneum and determine whether this is a unique skin type, we have evaluated a range of skin parameters, comparing these with the volar forearm. Trans-epidermal water loss and corneosurfametry revealed a reduced barrier function in the axilla. However, application of antiperspirant had no effect upon these barrier properties. High performance thin layer chromatography analysis of stratum corneum lipids demonstrated statistically elevated levels of fatty acids, ceramide and particularly cholesterol in the axilla. This modification of barrier lipid ratios appeared to result in a more ordered lipid lamellae phase behaviour, as determined by attenuated total reflectance Fourier transform infrared spectroscopy, with transition phase changes occurring at higher temperatures. Morphological differences were also seen in the cells of the axillary stratum corneum. Microscopic evaluation of axillary-cornified envelopes revealed them to be smaller, indicative of a shorter stratum corneum turnover. However, there appeared to be no significant difference corneocyte maturation. ,Skin dryness' squamometry measurements indicated that the axillary stratum corneum retained desquamated material on its surface more than on the forearm. This correlated with decreased levels of the desquamatory stratum corneum chymotryptic enzyme in the surface layers of the skin. These results indicate that the axilla has a distinct phenotype. Paper presented at the 22nd IFSCC Congress 2002, Edinburgh, Scotland [source] Formation of Lipid Emulsions and Clear Gels by Liquid Crystal EmulsificationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2007T. Suzuki Recently developed emulsion technologies for the formation of fine emulsions, lipid emulsions and clear gels by liquid crystal emulsification were reviewed. As a basic information on liquid crystal emulsification, the structures and characteristic behaviours of lyotropic liquid crystals were summarized. Formation of a liquid crystalline phase was often seen in emulsions and biological systems. The significance of liquid crystal formation during emulsification was analysed by comparing the states and stabilities of emulsions prepared by different processes. Then uses of liquid crystals for formation of the characteristic emulsions and gels were also discussed. In liquid crystal emulsification, an oil phase is dispersed directly into the lamellar liquid-crystalline phase composed of surfactant, glycerol and water to prepare a gel-like oil-in-liquid crystal emulsion. This is followed by dilution with the remaining water to produce an emulsion. From the phase behaviour during emulsification and analysis of the local motion of the liquid crystal membrane by fluorometry, it was confirmed that the interaction between surfactant and a polyol molecule such as glycerol promotes hydrogen bonding and enhances the strength of the lamellar liquid crystal membranes, which results in the formation of oil-in-liquid crystal emulsions. The interaction between the liquid crystal and oil was analysed from the changes in molecular motion of the membrane at the oil-liquid crystal interface using the spin label technique of electron spin resonance (ESR). The fluidity of the liquid crystal membrane did not change when oil was added, and therefore oil-in-liquid crystal emulsions of various oils were prepared by the identical process. This lack of dependence of the liquid crystal membrane on oil results in the unique properties of liquid crystal emulsification, which can be used for oils of various polarity and different molecular constituents. When a self-organizing artificial stratum corneum lipid containing pseudo-ceramide was used as a principal component of the oil, a multilamellar emulsion of concentric lamellar structure was formed. The multilamellar emulsion supplements the physiological function of stratum corneum by the identical mechanism as natural intercellular lipids. High-pressure treatment of the lipid emulsion produced a gel-like emulsion crystal, in which the homogeneous nanoemulsion droplets were arranged in a hexagonal array. This review paper was presented at the Conference of the Asian Societies of Cosmetic Scientists 2005 in Bangkok. [source] Stratum corneum keratin structure, function and formation , a comprehensive reviewINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2006L. Norlén Synopsis A comprehensive review on stratum corneum keratin organization, largely based on the recently published cubic rod-packing and membrane templating model [J. Invest. Dermatol., 123, 2004, 715], is presented. Keratin is the major non-aqueous component (wt/wt) of stratum corneum. As 90,100% of the stratum corneum water is thought to be located intracellularly one may presume that keratin also is a major factor (together with filaggrin-derived free amino acids) determining stratum corneum hydration level and water holding capacity. This water holding capacity depends in turn on the structural organization of the corneocyte keratin intermediate filament network. The cubic rod-packing model for the structure and function of the stratum corneum cell matrix postulates that corneocyte keratin filaments are arranged according to a cubic-like rod-packing symmetry. It is in accordance with the cryo-electron density pattern of the native corneocyte keratin matrix and could account for the swelling behaviour and the mechanical properties of mammalian stratum corneum. The membrane templating model for keratin dynamics and for the formation of the stratum corneum cell matrix postulates the presence in viable epidermal cellular space of a highly dynamic small lattice parameter (<30 nm) membrane structure with cubic-like symmetry, to which keratin is associated. It further proposes that membrane templating, rather than spontaneous self-assembly, is responsible for keratin intermediate filament formation and dynamics. It is in accordance with the cryo-electron density patterns of the native keratinocyte cytoplasmic space and could account for the characteristic features of the keratin network formation process, the dynamic properties of keratin intermediate filaments, the close lipid association of keratin, the insolubility in non-denaturating buffers and pronounced polymorphism of keratin assembled in vitro, and the measured reduction in cell-volume and hydration level between stratum granulosum and stratum corneum. Résumé, La kératine est le composant majeur anhydre de la couche cornée. Etant donné que l'on considère que 90 à 100% de l'eau de la couche cornée est localisée à l'intérieur des cellules, on peut penser que la kératine joue également un rôle important (en association avec les acides aminés libres dérivés de la filagrine) dans le niveau d'hydratation de la couche cornée et sa capacité de rétention de l'eau. Cette capacité de rétention de l'eau dépend elle-même de l'organization structurelle du réseau de filaments intermédiaires de la kératine des cornéocytes. Le modèle de cylindre en réseau cubique appliquéà la structure et aux fonctions de la matrice des cellules de la couche cornée stipule que les filaments de la kératine des cornéocytes sont disposés symétriquement, les paquets de fibrilles formant une structure cubique. Ceci est conforme au modèle de densité cryo-électronique de la matrice kératinique des cornéocytes natifs et pourrait expliquer le comportement de gonflement et les propriétés mécaniques de la couche cornée des mammifères. Le modèle d'assemblage membranaire appliquéà la dynamique de la kératine et à la formation de la matrice cellulaire du stratum cornéum postule la présence dans l'espace cellulaire viable de l'épiderme d'une structure membranaire hautement dynamique présentant un petit paramètre de maille (<30 nm) et une organization en forme de cube, à laquelle la kératine est associée. D'autre part, ce modèle suggère qu'un assemblage membranaire plutôt qu'un auto-assemblage spontané puisse être à l'origine de la formation des filaments intermédiaires de kératine et de leur dynamique. Ceci concorde avec les modèles de densité cryo-électronique du cytoplasme des kératinocytes natifs et pourrait expliquer les caractéristiques du processus de formation du réseau kératinique, les propriétés dynamiques des filaments intermédiaires de kératine, l'association de la kératine avec les lipides, l'insolubilité dans les tampons non dénaturants, le polymorphisme caractéristique de la kératine assemblée in vitro, ainsi que la diminution mesurée du volume cellulaire et du niveau d'hydratation entre le stratum granulosum et le stratum corneum. [source] The biology of vernix caseosaINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2006S. B. Hoath Synopsis The biology and physical properties of the uniquely human skin cream ,vernix caseosa' are discussed. This material coats the foetal skin surface during the last trimester of gestation and provides multiple beneficial functions for the foetus and newborn infant. Vernix has a complex structure similar to stratum corneum but lacks lipid lamellae and is more plastic due to the absence of desmosomal constraints. In utero, vernix is made in part by foetal sebaceous glands, interacts with pulmonary surfactant, detaches into the amniotic fluid, and is swallowed by the foetus. At the time of birth, vernix has a remarkably constant water content approximating 80%. Postnatally, vernix is simultaneously a cleanser, a moisturizer, an anti-infective, and an anti-oxidant. Vernix facilitates acid mantle development and supports normal bacterial colonization. Its hydrated cellular structure and unusual lipid composition provide a ,best' solution for the needs of the foetus and newborn, not least of which is the attraction of caregivers. Vernix is an important natural biomaterial of potential interest to cosmetic scientists, and other disciplines involved in product development and therapies targeting the complex interface between the stratum corneum and a changing terrestrial environment. Résumé La biologie et les propriétés physiques de la crème de peau exclusivement humaine ,Vernix caseosa « sont discutées. Ce matériau couvre la surface de la peau foetale pendant le dernier trimestre de gestation et remplit des fonctions avantageuses multiples pour le foetus et le nouveau-né. Le Vernix a une structure complexe semblable au stratum corneum, mais manque de lamelles lipidiques et est plus plastique en raison de l'absence de contraintes desmosomales. In utero, le Vernix est constitué en partie par des glandes sébacées foetales, il interagit avec le surfactant pulmonaire, il se détache dans le liquide amniotique et est avalé par le foetus. Au moment de la naissance, le Vernix a une teneur remarquablement constante en eau de l'ordre de 80%. Après la naissance, le Vernix devient simultanément un produit de lavage, un produit hydratant, un anti-infectieux et un anti-oxydant. Le Vernix facilite le développement du manteau acide et soutient la colonisation bactérienne normale. Sa structure cellulaire hydratée et sa composition en lipide inhabituelle en font ,une des meilleures » solutions pour les besoins du foetus et du nouveau-né, à laquelle le personnel soignant n'attache pas la moindre importance. Le Vernix est un biomatériau naturel important potentiellement intéressant pour les scientifiques cosméticiens et pour les autres disciplines impliquées dans le développement de produits et de thérapies visant l'interface complexe entre le stratum corneum et un environnement terrestre changeant. [source] Ethnic skin types: are there differences in skin structure and function?,INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2006A. V. Rawlings Synopsis People of skin of colour comprise the majority of the world's population and Asian subjects comprise more than half of the total population of the earth. Even so, the literature on the characteristics of the subjects with skin of colour is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large-scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin colour which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes between the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally Caucasians have an earlier onset and greater skin wrinkling and sagging signs than other skin types and in general increased pigmentary problems are seen in skin of colour although one large study reported that East Asians living in the U.S.A. had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease-activated receptor-2 which together with its activating protease is increased in the epidermis of subjects with skin of colour. Changes in skin biophysical properties with age demonstrate that the more darkly pigmented subjects retaining younger skin properties compared with the more lightly pigmented groups. However, despite having a more compact stratum corneum (SC) there are conflicting reports on barrier function in these subjects. Nevertheless, upon a chemical or mechanical challenge the SC barrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to Caucasian skin and similar ceramide levels but upon mechanical challenge it has the weakest barrier function. Differences in intercellular cohesion are obviously apparent. In contrast reduced SC natural moisturizing factor levels have been reported compared with Caucasian and African American skin. These differences will contribute to differences in desquamation but few data are available. One recent study has shown reduced epidermal Cathepsin L2 levels in darker skin types which if also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms as the desquamatory enzymes are extruded with the lamellar granules subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sebum secretion and skin surface microflora occur in Negroid subjects. Equally increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups but the stimuli for its induction shows subtle differences. Nevertheless, several studies indicate that Asian skin maybe more sensitive to exogenous chemicals probably due to a thinner SC and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types but clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types. Résumé, Les gens qui ont une peau de couleur représentent la majorité de la population mondiale et les sujets asiatiques en représentent plus de la moitié. Pourtant la littérature consacrée aux caractéristiques de ces sujets est limitée. Plusieurs groupes de travail ont essayé au cours des dernières années de comprendre les différences sous-jacentes de la structure et de la fonction de la peau de différentes ethnies. Maisla plupart de ces études ont été réalisées à petite échelle et dans certains cas les différences observées entre les individus au niveau de la qualité de la peau ne font pas ressortir de différence entre races. Récemment, un besoin d'études reliant les diffèrences génétiques et phénotypiques entre différents groupes raciaux s'est fait sentir et de ce fait beaucoup d'études à grande èchelle ont été entreprises. La différence la plus évidente, entre les peaux ethniques, est leur couleur liée à la présence de la mélanine. La photoprotection induite par ce polymère influence le taux de vieillissement de la peau entre les différents groupes raciaux qui finalement sont tous sujets au processus de photovieillissement. Généralement, les caucasiens ont des signes plus précoces et plus importants de formation de rides et de relâchement de la peau; en général, les problèmes d'augmentation de la pigmentation sont observés sur les peaux de couleur, bien qu'une grande étude ait rapporté que des sujets originaires de l'Asie de l'Est vivant aux U.S.A. avaient le moins de taches pigmentaires. On pense que la réponse d'une induction hyperpigmentaire est due à un signal envoyé par le récepteur 2 activé par une protéase. Le récepteur 2 augmente en même temps que la protéase activatrice dans l'épiderme des sujets ayant une peau de couleur. Les changements dans les propriètés biophysiques de la peau en fonction de l'âge montrent que les sujets qui ont la pigmentation la plus sombre gardent une peau plus jeune par comparaison aux groupes qui possèdent une pigmentation moins forte. Toutefois, bien qu'ayant un stratum corneum plus compact, il existe des rapports divergents sur la fonction barrière de ces sujets. Dans le cas d'agression chimique ou mécanique, la fonction barrière du stratum corneum est considérée plus forte chez les sujets à peau plus foncée, malgré leurs taux plus faibles encéramide. On doit garder à l'esprit que la fonction barrière du stratum corneum dépend de toute son architecture et pas seulement de sa teneur en lipides. On considère que la peau asiatique à unePIE (TEWL) basale similaire à la peau caucasienne, ainsi que des taux en céramides comparables, mais on constate que dans le cas d'agression mécanique, elle possède un effet barrière le plus faible. Des différences dans la cohésion intercellulaire sont évidentes. A contrario, on a mis en évidence des taux d'hydratation (NMF) plus faibles dans son stratum corneum, comparativement à la peau caucasienne et afro-américaine. Ces différences expliquent les variations au niveau de la desquamation, mais on a très peu de données sur ce sujet. Une étude récente a mis en évidence des taux réduits de Cathepsin L2 dans l'épiderme des types de peau plus sombre, ce qui, si cela se produisait dans le stratum corneum, expliquerait les problèmes biens connus de cendrage de la peau que ces sujets connaissent. En terme très gènéral, étant donné que les enzymes liées à la desquamation sont libérées avec les granules lamellaires, on s'attend à ce que les sujets ayant des taux de lipides faibles dans le stratum corneum aient des taux d'enzymes liés à la desquamation faibles. On constate chez les sujets noirs une augmentation de la taille des pores, de la sécrétion du sébum et de la microflore cutanée. On observe également chez ces sujets une augmentation de la taille des granules mastocellulaires. Le phénomène de peau sensible se retrouve à une fréquence similaire dans les différents groupes raciaux, mais il existe des différences subtiles dans lesstimuli nécessaires pour l'induire. En tout cas, plusieurs études montrent que la peau asiatique est peut-être plus sensible aux produits chimiques exogènes, ce qui probablement est dûà un stratum corneum plus mince et à une densité de glandes eccrines plus élevées. En conclusion, c'est sur les caractéristiques biophysiques et somato-sensorielles des différents types de peaux ethniques que nous en savons plus, mais il est clair qu'il nous reste à comprendre encore beaucoup de choses principalement sur leurs différences biologiques. [source] Influence of environmental stress on skin tone, color and melanogenesis in Japanese skinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005K. Kikuchi Introduction It is needless to say that one of the most potent environmental stress for melanogenesis of the human skin is the effect of ultraviolet (UV) light from the sunlight. Characteristic skin aging as a result of this UV light is recognized as photoaging. Clinical features in photoaging are wrinkles, skin laxity, coarseness, leathery, yellowing, lentigenes, mottled pigmentation, telangiectasia, sebaceous hypertrophy and purpura. There is an apparent difference in clinical features in photoaging among different races, i.e. between Caucasians, African American and Asians that include Japanese. Not only photo skin type but also environmental factors, such as climate, latitude, altitude and their habit of sunbathing, smoking and skin care influence the characteristic development of their photoaging. Racial difference in photoaging Caucasians tend to develop skin laxity and fine wrinkles more than Asians [1]. Asians tend to produce coarser wrinkles than the Caucasians although their development is rather late in life. There is also a difference in the skin color. Pigmentation is an earliest and prominent skin changes in Asians [1] and it increases with age [2]. In contrast, pigmentation is not apparent in the Caucasians although redness probably because of an increase in cutaneous vascularization becomes prominent in middle aged Caucasians [2]. Chung reported that seborrheic keratosis is a major pigmentary lesion in men, whereas hyperpigmented macules are prominent features in women in Koreans [3]. Melanogenesis pigmentation disorders in Japanese Ephelides (freckles) are commonly found in those with photo skin type I who have fair skin and red eyes and blond hair. They are also found in the Japanese. Clinical feature reveals that multiple small pigmentary macules on sun-exposed areas mainly on the mid-portion of the face. These lesions seem to be familial, becoming apparent even in early childhood after sun exposure. Melasma is an acquired pigmentary disorder commonly found in middle aged Japanese women characterized by irregular brown macules and patches on the sun-exposed areas on the face typically as bilaterally present macules on the cheeks. An increase in sex hormones as a result of pregnancy and intake of contraceptive pills is one of the etiological factors to develop melasma. Sun exposure also worsens it. Nevus of Ota is also a common pigmentary disorder found in the Japanese. It is usually unilateral, blue-brown to slate-gray pigmentary macules on the eyelid and cheek that appear in early childhood or in puberty. Acquired dermal melanocytosis is also a pigmentary disorder, in which dermal melanocytes are found as shown in nevus of Ota, characterized by bilateral brown to blue-gray macules on the forehead, temple, eyelid and malar areas in middle aged Japanese women. This tends to be misdiagnosed as melasma. Solar lentigo is an acquired pigmented macule induced by sun exposure. Solar lentigines are usually multiple, circumscribed brown macules. There are two types of solar lentigo. One is a small macular type, characterized by multiple, small brown macules whose diameter is less than 5 mm, being similar to ephelides (freckles). The other type is a large macular type, characterized by a few round to oval, brown macules whose diameter is beyond 1 cm. Some of their surface are hyperkeratotic and become elevated to produce seborrheic keratosis. Again, the early sign of photoaging in Japanese is pigmentated spots and these pigmentation disorders increase with age. Among the pigmentary changes, nevus of Ota, acquired dermal melanocytosis, melasma and large macular type of solar lentigo are characteristic skin changes found in the Japanese in addition to ephelides and small macular type of solar lentigo. Seasonal changes of the various functional properties of the skin including skin color assessed by non-invasive bioengineering techniques [4]. When we consider skin tone, color and melanogenesis, UV light from the sunlight is the most potent environmental stress, although we cannot forget also the important influence of environmental relative humidity affects our skin functions as well as its appearance. We investigated seasonal influences on the various properties of the skin in 39 healthy Japanese females consisting of different age groups. Their skin is thought to be affected by the UV light in summer, and by the exposure to the dry and cold air in winter. Materials and methods Biophysical, non-invasive 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, skin color and casual surface lipid levels, were conducted during late summer and winter months. Skin color was determined with a chromameter according to the L*a*b* CIE 1976 system, where L* is an attribute on the luminance scale, a* that on the red versus green scale and b* that on the yellow versus blue scale. All the measurements were conducted in an environment controlled-chamber (21 ± 1 °C room temperature, and 50 ± 3% relative humidity). Results The barrier function of the SC was found to be significantly impaired in winter on the cheek as compared with that measured in summer, whereas no such seasonal change was apparent both in the hydration state of the SC and sebum levels on the cheek. In the assessment of the skin color on the cheek, a significant increase in a* (redness) and a decrease in b* (yellowness) were observed in winter. In contrast, on the flexor forearm, the values of L* (luminescence) increased in winter, but no seasonal change was noted in the values of a* and b*. In this study, skin changes with aging were also found by the non-invasive bioengineering methods. The value of TEWL on the cheek tended to increase with age, whereas no significant change was observed in the value of TEWL on the forearm. In the assessment of skin color, b* value on the cheek significantly increased with age whereas a* and L* values on the cheek did not show any significant change with age. Summary of this study We think that such an increase in yellowness with aging of the cheek skin is a phenomenon unique to the Japanese (Asians) since an increase in b* value was not observed in Caucasians [2]. The facial skin that is always exposed shows barrier impairment in a dry and cold winter environment and demonstrates increased yellowness in skin color because of a prolonged exposure to the UV light from the sun in the summer season. The non-invasive bioengineering methods are useful to demonstrate even invisible seasonal changes occurring in the same individuals and changes with age occurring in the skin. References 1.,Goh, S.H. The treatment of visible signs of senescence: the Asian experience. Br. J. Dermatol.122, 105,109 (1990). 2.,LeFur, I., Numagami, K., Guinot, C. et al. Age-related reference values of skin color in Caucasian and Japanese healthy women according to skin site. Pigment Cell Res. 7, 67 (1999). 3.,Chung, J.H., Lee, S.H., Youn, C.S. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 4.,Kikuchi, K., Kobayashi, H., Le Fur, I. et al. Winter season affects more severely the facial skin than the forearm skin: comparative biophysical studies conducted in the same Japanese females in later summer and winter. Exog. Dermatol. 1, 32,38 (2002). [source] Peau sèche-rêche et "Hydratation".INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004Concept de la capture de l'eau organisée comme de la glace Synopsis About sixty years ago Frank and Evans showed, by entropy measurements, that when a "non-polar molecule dissolves in water it modifies the water structure in the direction of greater ,cristallinity', the water builds a microscopic iceberg around it" Now, we propose the "concept of ice-like-water capture": a lowering of organized ice-like water promotes aggregation (loss of solubility) of the filaggrin/keratin1/keratin10 associations through their hydrophobic patches. The capture of ice-like water may be performed by the glucoceramides-rich bilayers in stratum granulosum. Probably, the same process aggregates the proteins of corneocytes envelope as well as corneodesmosomes proteins. According to the "concept of ice-like-water capture", to regulate the keratinization, it is not total water that must be added to the stratum corneum, but ice-like water that must be removed from stratum granulosum. Both petrolatum (lipophilic ingredient) and glycerol (hydrophilic ingredient) would capture the ice-like water, most probably after combination with the lipid bilayers of stratum corneum. Moisturizing cream, when organized in secondary droplets is likely to perform the same action. Measurements by near-infrared reflectance spectroscopy of the skin show that petrolatum; glycerol and/or moisturizing cream enhance the quantity of bulk water (1890,1897 nm band). As the ice-like water is the complement of bulk water, the enhanced bulk water let presume an ice-like water lessening. Some desynchronization (late or forward) of the keratinization/differentiation which confer the somatosensory problems associated with "dry and flaky skin" may be linked to an excess or lack of ice-like. For instance, the winter xerosis, very common by chilling weather, could be explained by an increase of ice-like water driven by the fall of the temperature. Résumé En s'appuyant: 1°-sur d'anciens travaux de thermodynamique montrant, d'une part que les molécules d'eau autour des zones apolaires en solution dans l'eau s'organise selon une structure d'eau-comme-de-la-glace, d'autre part qu'en l'absence de cette eau-comme-de-la-glace les molécules de protéines s'agrègent par leurs zones hydrophobes; 2°-sur des travaux récents utilisant la spectroscopie de l'infrarouge proche; technique qui permet de mesurer la quantité d'eau-en-vrac, forme que prend l'eau-comme-de-la-glace après sa fusion lors de l"établissement de liaisons/interactions hydrophobes; nous proposons le "concept de la capture de l"eau-comme-de-la-glace" selon lequel : 1° la différenciation des kératinocytes, qui se traduit à la fois par l'agrégation des trios filaggrine/K1/K10 (ainsi que notamment la formation de l'enveloppe des cornéocytes et des cornéodesmosomes) est promue par une baisse de la teneur en eau organisée dans le stratum granulosum. La captation de l'eau-comme-de-la-glace pourrait être assurée in situ par la structure lipidique riche en glucocéramides dont l'apparition dans le stratum granulosum est contemporaine du début de la baisse de la teneur en eau; 2° contrairement à la "tradition", la peau sèche-rêche n'est pas améliorée par une augmentation de l'hydratation du stratum corneum mais par la capture d'eau-comme-de-la-glace dans le stratum granulosum. 3° le glycérol, la Vaseline et les crèmes "hydratantes" peuvent concourir à cette capture d'eau-comme-de-la-glace, vraisemblablement après s"être combinés aux bicouches céramidiques du stratum corneum, et ainsi agir depuis ce stratum sur le stratum granulosum. 4°-la baisse hivernale de la température provoque une baisse de la quantité d'eau organisée et confère une aggravation de la peau sèche-rêche. 5°-une désynchronisation de la synthèse ou une modification de la structure et/ou de la composition des bicouches glucocéramidiques du stratum granulosum pourraient être à l'origine de certains types de peau sèche-rêche. [source] Original semiologic standardized evaluation of stratum corneum hydration by Diagnoskin® stripping sampleINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2004P. Gasser Synopsis In a normal and healthy skin, the regular elimination of the superficial corneocytes, called desquamation, is a fundamental physiologic process intended to protect the barrier function of the skin. This invisible loss of corneocytes, individually or in small groups, is incessantly compensated by the divisions of the proliferative layer and the upward cellular maturation in order to maintain the harmonious renewal of the epidermis and the integrity of the stratum corneum. The harmony of this desquamation process is intimately conditioned by a sufficient hydration of the stratum corneum: (i) an abnormal desquamation leads to a disruption of the water barrier function and consequently to a dehydration tendency of the stratum corneum, and (ii) a cutaneous dryness (whatever the cause) is able to disturb the desquamation process. Protecting the water content of the stratum corneum has always been a major preoccupation of the cosmetic industry scientists. Consequently, the moisturizing properties of a cosmetic product are objectively measured by various explorations directly targeted on the hydration (corneometry) and on the level of the water barrier function (transepidermal water loss (TEWL) measurements), which depends directly on the skin hydration state. This intimate linkage of the desquamation process and the water content of the stratum corneum enable us to suggest an indirect assessment of the hydration from a direct study of the desquamation by examining a skin-stripping sample (D-Squames®) by an optical microscope (linked to a computer). We will describe this already known technique and mainly its new and unpublished semiologic exploitation, named Diagnoskin®, whose advantages are its simplicity and its reproducibility particularly interesting in the case of sequential appraisal of dermatologic or cosmetic treatments. Résumé Sur une peau normale et saine, l'élimination régulière des cornéocytes superficiels, appelée desquamation, est un processus physiologique fondamental destinéà préserver la fonction barrière de la peau. La perte invisible des cornéocytes, individuellement ou par petits paquets cellulaires, est sans cesse compensée par les divisions de la couche germinative et la maturation cellulaire ascensionnelle afin de maintenir le renouvellement harmonieux de l'épiderme et l'intégrité du stratum corneum. L'harmonie de ce processus de desquamation est intimement conditionnée par une hydratation suffisante du stratum corneum: une desquamation anormale aboutit à une perturbation de la fonction barrière et donc à une tendance à la déshydratation du stratum corneum, Une sècheresse cutanée (quelle qu'en soit la cause) va perturber la desquamation. Préserver la teneur en eau du stratum corneum est depuis toujours une préoccupation majeure pour le scientifique de l'industrie cosmétique. L'appréciation objective du caractère hydratant d'une crème cosmétique est d'ailleurs mesuré par diverses explorations directement ciblées sur l'hydratation (cornéométrie) et sur l'état de la fonction barrière (Perte Insensible en Eau ,PIE) qui dépend directement de l'état d'hydratation de la peau. Cette liaison intime du niveau d'hydratation du stratum corneum et du phénomène de desquamation nous a fait proposer une évaluation indirecte de l'hydratation à l'aide d'une étude directe de la desquamation par observation au microscope (reliéà un ordinateur) des prélèvements par stripping des cornéocytes superficiels (D-Squames®). Nous décrirons cette technique déjà connue et surtout son exploitation sémiologique nouvelle et inédite, appelée Diagnoskin® dont les avantages sont sa simplicité et son caractère reproductible particulièrement intéressants pour l'évaluation séquentielle de traitements dermatologiques ou cosmétiques. [source] | ||||||||||||||||