Stress and the skin

'The skin is the mirror which reflects the state of the mind.'The skin is the window of the mind.' These have been proverbs since ancient times. It is the topic of this article. Our life became convenient with the information technology these days but too much information often drives us on. We suffer from mental stress rather than physical stress. Since Selye advocated stress reaction, various reactions in the body have been described. Skin is also a target organ of the stress reaction. What the effects of stress are and how stress affects the skin are summarized in this review. Possible use of fragrance for the regulation of the stress reaction is also introduced.     

Surfactants and the skin

The skin surface is the interface between us, the organism, and the outside world. When we clean the skin we remove not only the bacteria, dirt and grease which have accumulated, but also part of our natural barrier - the stratum corneum. Corneocytes, both singly and in clumps, are released from the skin surface by the action of detergents and mechanical stimulation. So too are the lipids and proteins which make up the intercorneocyte region of the stratum corneum. The analysis of the types and amounts of materials released by a standard scrub procedure may prove useful in the selection of surfactants with particular properties. Changes in the physical properties of the skin occur after washing. For example, changes in skin surface pH and transepidermal water loss (a sensitive index of barrier function) are easily demonstrable. Excessive exposure to surfactants results in repeated damage to the stratum corneum which can in turn lead to an irritant dermatitis. Individual susceptibility to irritant dermatitis varies and this may be demonstrated using a simple patch test technique. This test is a way of potentially increasing the sensitivity of human based assays such as the soap chamber test by preselection of subjects. Alternatively it may be possible to use measurements of function such as transepidermal water loss or laser Doppler blood flow as an index of damage rather than conventional cutaneous irritancy. These approaches may help in the search for the ideal of a non-irritant cleanser.     

Oat-based complex stimulates skin barrier protein synthesis and reduces skin ageing

Citation: IFSCC Magazine , 11 (2008) (3) 225–229
The dermis is considered a highly dynamic structure that determines the biomechanical properties of the skin. It is composed of two dermal compartments separated by a vascular plexus: the papillary dermis and the reticular dermis. In the last few years, several studies have demonstrated the role of the dermal epidermal junction in the cutaneous ageing process. Recently, teams specialized in the study of the dermal matrix have focused their studies on the superior dermis in close contact with the dermal epidermal junction: the papillary dermis. They defined the role of matrix proteins in this area. Collagens XII and XVI, non-fibrillar collagens specific to the papillary dermis, are responsible for skin deformability and extensibility. Oxytalan fibres are related to elastic properties of the skin. Ubiquitous collagens such as collagens I and VI are associated with the cohesion and the resistance of the dermis. As the papillary dermis is the primary site of intrinsic dermal ageing, we studied expression of these molecules in our own in vitro model of intrinsic ageing of the papillary dermis. The results of this innovative approach confirmed that their expression was reduced. Nevertheless, active molecules may exist in nature that are capable of restoring a normal expression profile of these markers for a cosmetic anti-ageing application.
Keywords:  Anti-ageing, papillary dermis, collagens XVI and XII, oxytalan fibres     

发用类、肤用清洁类化妆品的急性皮肤和眼刺激损害特点

分析发用类、肤用清洁类化妆品的急性皮肤刺激和急性眼刺激损害特点,了解其卫生安全状况。于2012年采用《化妆品卫生规范》(2007年版)中的急性皮肤刺激性实验和急性眼刺激性实验对发用类、肤用清洁类共计158种化妆品样品进行测试。两类受试化妆品显示出不同程度的急性皮肤刺激性和急性眼刺激性损害效应。发用类化妆品在实验中基本无皮肤刺激性损伤;肤用清洁类化妆品在实验中有少量的皮肤刺激性损伤,但大都为轻刺激性(31.0%),只有个别(3.8%)出现了皮肤红斑水肿的中刺激性损伤。发用类、肤用清洁类化妆品在急性眼刺激性实验中检出一定比例具有微刺激性及以上刺激性的样品,但引起的眼损伤都能够在观察期限内恢复。本次调查的所有化妆品中,洁面类、洗发类化妆品普遍具有急性眼刺激性和急性皮肤刺激性损害,需加强对化妆品的监督管理,进一步提升化妆品卫生安全水平,保障化妆品使用安全。     

鲨鱼皮胶原与罗非鱼皮胶原的理化性质及酶解特性研究

为了系统比较深海鱼和淡水鱼胶原的差异,利用酸法提取鲨鱼皮胶原和罗非鱼皮胶原,并对它们的理化性质和酶解特性进行了考察。氨基酸组成分析表明,鲨鱼皮胶原中异亮氨酸含量大约是罗非鱼皮胶原的2倍,但脯氨酸含量较少。鲨鱼皮胶原α肽链和β肽链的分子量,以及胶原热变性温度都低于罗非鱼皮胶原,但在紫外光谱和红外光谱中没有发现明显的差异。另一方面,电泳图谱和液相图谱都表明,鲨鱼皮胶原和罗非鱼皮胶原容易被胶原酶和胰蛋白酶酶解,不易被木瓜蛋白酶酶解。在胶原酶与底物质量比为0.05%,pH8.0和50℃的酶解条件下,经过240min酶解,鲨鱼皮胶原肽中小于1000u的肽含量达到23%,而罗非鱼胶原肽中却只有17%。      

Spectrofluorescence of skin and hair

There are numerous chromophores present throughout the strata of human skin, which present many challenges and opportunities to probe molecular events. Fluorescence spectroscopy is principally employed to identify important biochemical components of the skin including endogenous tryptophan, tyrosine, pepsin-digestible collagen cross-links, collagenase-digestible collagen cross-links, NADH, etc. Over the last 15 years, many advances in instrument technology have been introduced allowing for much faster data acquisition with spectrofluorometers. As a result, a series of spectrofluorescence emission scans can be generated for a range of excitation wavelengths, or vice versa (excitation scans for a range of emission wavelengths), quickly to generate excitation-emission matrices. In this work, we constructed an endogenous fingerprint of fluorescent compounds present in skin, hair and nail tissues by employing a range of excitation wavelengths from 270 to 450 nm with a resolution of 2 nm. As a result, we generated surface plots of fluorescence emission as a function of excitation and emission wavelengths. From these data, we identified the predominant fluorescent chromophores in each tissue. We examined several sources of skin including in vivo human and ex vivo pig, sheep, goat and cow skin. We also analysed various types of mature hair characterized by the degree of melanin content. These analyses provided us with a fundamental understanding of the effects of melanin distribution in hair fibres and aided with the identification of fluorophores present in hair.     

中国皮革及制品进／出口金额表

美丽除了气质以外，重要的是皮肤，根据春季的气候特点和皮肤的状态，应该采取有效的护理方法；首先要注意清洁肌肤，用质量好的洁面乳洗面，其次要补充水分，适当补充水分可以使肌肤滋润延缓衰老。[编者按]     

Glycation induction and antiglycation activity of skin care ingredients on living human skin explants

Glycation is an ageing reaction of naturally occurring sugars with dermal proteins, whose clinical signs may appear in vivo around age 30, and increases steadily/regularly with age. The suppleness of the dermis is affected by the formation of bridges between proteins and sugars (Maillard's reaction). The residues formed (Amadori products, Advanced Glycation End products) as well as the proteins they alter, can be visualized by specific immunostainings. Induced in a few days on living skin explants by methylglyoxal, glycation can be prevented by the application of aminoguanidine HCl, the reference anti-glycation molecule. This model enabled to highlight the anti-glycation activity of substances of vegetal origin such as puerarin and chlorogenic acid.     

Image analysis to quantify histological and immunofluorescent staining of ex vivo skin and skin cell cultures

Image processing steps and analysis techniques were developed for the quantification of photomicrographs obtained from light and fluorescence microscopy. The substrates examined were either skin cell cultures, such as normal human keratinocytes (NHK) or fibroblasts, or ex vivo skin sections. Examples of the analyses are provided for the comparison of skincare active ingredient treated samples vs. placebo to demonstrate the utility of the methods to quantify and provide numerical data for a procedure that is typically qualitative in nature and based on observations by a histologist. Quantifiable experiments that are discussed include: Fontana Masson staining for melanin expression; Nile red staining to detect cellular lipid droplets; nuclei staining with diamidino‐phenylindole (DAPI); and immunofluorescent staining of protein expression with a primary antibody directed against the protein (antigen) and a secondary antibody tagged with a fluorescent dye (Alexa Fluor 488) against the primary antibody.     

Sensitive skin: mechanisms and diagnosis

Sensitive skin is a condition of subjective cutaneous hyperreactivity to environmental factors. Subjects experiencing this condition report exaggerated reactions when their skin is in contact with cosmetics, soaps and sunscreens, and they often report worsening after exposure to dry and cold climate. Although no sign of irritation is commonly detected, itching, burning, stinging and a tight sensation are constantly present. Generally substances that are not commonly considered irritants are involved in this abnormal response. They include many ingredients of cosmetics such as: dimethyl sulfoxide, benzoyl peroxide preparations, salicylic acid, propylene glycol, amyldimethylaminobenzoic acid and 2-ethoxyethyl methoxycinnamate. Sensitive skin and subjective irritation are widespread but still far from being completely defined and understood. The aim of this paper is to summarize the relevant literature in order to elucidate the underlying mechanisms of sensitive skin and the best testing methodologies for investigation of sensitive skin.     

Axillary skin: biology and care

In skin care, the axilla is a biologically unique site requiring specialized attention and care. This area of skin is often subject to hair removal techniques, such as shaving and plucking. These procedures damage the skin leading to erythema and dryness in the short term, and in some cases, post-inflammatory hyperpigmentation (PIHP) in the long term. This study will (i) briefly review the biology and unique properties of axillary skin, and (ii) describe the characteristics of the irritation and damage induced by contemporary skin care habits and resolution of these responses by the use of efficacious skin moisturizing technology. With respect to the latter, we propose that there are five groups of compounds, defined according to their mechanism of action, which are particularly relevant to the care of damaged axillary skin.     

Dry skin, moisturization and corneodesmolysis

The process leading to the loss of corneocytes form the skin surface is termed desquamation. In healthy skin it is an orderly and essentially invisible process whereby individual or small groups of corneocytes detach from neighbouring cells to be lost to the environment and replaced by younger cells from the deeper layers. Desquamation is carefully controlled to ensure that corneum cohesion and integrity, and hence tissue thickness, is maintained. The most important components of the corneocytes contributing towards intercellular cohesion are the corneodesmosomes and lipids. Corneodesmosomes are proteinaceous complexes which effectively rivet corneocytes together. The intercellular lipids, primarily responsible for the water barrier, also provide part of the extracellular cement. In addition, the shape of the corneocyte itself plays a role in stratum corneum cohesion. Through interdigitation along their peripheral edges, adjacent corneocytes become physically locked together, a process which reinforces the integrity of the tissue. For effective desquamation to occur corneodesmosomes must be degraded: a process catalysed by serine proteases present within the intercellular space and facilitated by subtle changes in lipid composition and phase behaviour. Ultimately, it is the availability of free water which controls corneodesmolysis. In healthy skin this proteolytic process leaves relatively few corneodesmosomes intact in the most superficial layers. By contrast, in chronic and acute dry skin conditions, corneodesmosomal degradation and hence the final stages of desquamation are perturbed, leading to the characteristic formation of visible, powdery flakes on the skin surface. The inability to degrade these structures ultimately reflects a decreased hydrolytic activity of the desquamatory enzymes, either through reduced synthesis of the enzymes, inherent loss of activity, leaching from the surface layers of the corneum or changes in the surrounding lipid-rich microenvironment, which may indirectly reduce enzyme functionality. Increased understanding of the desquamation process is providing new insights into the mode of action of current moisturizing ingredients and is offering opportunities to develop novel therapies for preventing and correcting dry skin.     

Diffusion through skin and model systems

A new approach has been made to the investigation of diffusion through skin. The experimental procedure is to arrange for a self-exchange of radioactively labelled compounds through a skin or model membrane. A new mathematical solution for D*, the self-diffusion coefficient for the molecule, is computed and the variation in self-diffusion parameters noted with temperature, skin type, and model membrane. Some thermal analyses are given. La diffusion a travers des modèles de peau