正常人皮肤共振传导特性的研究

目的:研究我国正常人皮肤共振传导特性.方法:利用Reviscometer测量374例正常人手背、额部及眼外眦不同方向皮肤共振传导时间.利用直线回归法确定皮肤共振传导时间及其异向性与年龄的相关性.结果:在正常男女手背及眼外眦部位,各个测量方向的皮肤共振传导时间与年龄均呈明显的负相关;在正常男性额部,仅2～8、3～9和4～10点方向的皮肤共振传导时间与年龄呈明显的负相关;在正常女性额部,除1～7和5～11点方向外,其他各个方向的皮肤共振传导时间与年龄均呈明显的负相关:手背皮肤共振传导时间异向性与年龄也呈负相关(女P<0.000 1,男P<0.000 2);性别对皮肤某些方向的共振传导时间亦有一定的影响.结论:正常人皮肤共振传导时间及其异向性与年龄、部位和性别有关.     

银屑病和慢性荨麻疹患者自体血清皮肤试验检测

银屑病目前认为与遗传因素、环境因素、免疫因素有关.1 自体血清皮肤试验（ASST）在银屑病的检测未见报道。本实验在此方面进行了初步的研究。     

上海地区100例正常人紫外线最小红斑值测定

以SUV1000型日光紫外模拟仪为光源，测定上海地区100例正常人UVA-MED和UVB-MED正常值。不同性别和皮肤类型的受试者男性UVA-MED值明显高于女性（P〈0．01）；UVB-MED值在男女之间差异无统计学意义（P〉0．05）。IV型皮肤受试者UVA和UVB的MED值均大于Ⅲ型皮肤受试者。男性各年龄组UVA-MED均无显著性差异（P〉0．05）；UVB-MED30～49岁组与另外两组相比差异有显著性（P〈0．05）。女性UVA-MED10～29岁组与另外两组相比差异有显著性（P〈0．05），就日光暴露程度和MED值关系而言，各组间UVA和UVB的MED值差异无统计学意义。     

中国正常老年人与年轻人皮肤共振传导特性比较

目的 研究中国正常老年人和年轻人不同部位皮肤共振传导特性。方法 152例年龄20 ~ 40岁的正常年轻人和64例年龄60 ~ 88岁的正常老年人参加本研究。利用Reviscometer RVM600分别于左手背、左前臂屈侧、前额及左眼外眦处测量不同方向皮肤共振传导时间 （CRRT）。结果 CRRT因测量部位和方向的不同而不同。在前臂,除在2 - 8点方向外,其他各方向老年人的CRRT大于年轻人：0 - 6点方向,t = 7.46;1 - 7点方向,t = 3.38;3 - 9点方向,t = 3.88;4 - 10点方向,t = 6.82;5 - 11点方向,t = 7.42,P值 < 0.01或 < 0.05。在手背部位,除在3 - 9点方向外,其他各方向年轻人的CRRT则大于老年人：0 - 6点方向,t = 4.53;1 - 7点方向,t = 5.71;2 - 8点方向,t = 2.74;4 - 10点方向,t = 2.67;5 - 11点方向,t = 4.20,P值均 < 0.01或 < 0.05。在前额部位,年轻人的CRRT与老年人差异无统计学意义。在眼外眦部位的1 - 7点和2 - 8点方向,年轻人CRRT大于老年人：1 - 7点方向,t = 3.18,P < 0.01;2 - 8点方向,t = 5.11,P < 0.01。男女之间各部位CRRT没有明显差异。结论 CRRT因年龄、方向及部位的不同而不同,性别对CRRT没有明显影响。     

Influence of the hydrophobic and hydrophilic characteristics of sliding and slider surfaces on friction coefficient: in vivo human skin friction comparison

INTRODUCTION: The objective of this study was to investigate whether hydrophilic/hydrophobic balance (Hi/Ho) of the skin surface strongly modifies the friction coefficient (mu).The Hi/Ho balance is determined using the relationship between the critical surface tension gammac (Zisman's principle:which delimits the wetting capacity) and the surface tension of water gammaH2O (water: reference element of Hi/Ho balance). METHOD: Critical surface tension gammac was determined (according to Zisman's principle) through the measurement of advancing contact angle theta of a series of ethanol/water dilutions. Friction coefficient depends on several parameters: types of probe motions (rotational vs. linear), surface roughness and physicochemical parameters of surfaces in contact).In this study, the wettability parameters for six surfaces (human skin forearm, Teflon, silicone impression material 'Silflo', vinyl polysiloxane impression material 'resin' steel and glass) were measured and their influences were compared to friction coefficient mu. RESULTS: This study shows that the higher hydrophobia tendency of the surfaces, the lower friction coefficient. The use of three sliding materials (Teflon, steel and glass) of different Hi/Ho balance confirms the importance of these physicochemical parameters in mu. For example, Teflon with high hydrophobia has a low mu. Friction coefficient increased when hydrophobia of sliding and slider surfaces decreased. CONCLUSION: Friction coefficient value depends on the type of slider surface and its physicochemical properties. In vivo,the friction coefficient may quantify the influence of lubrificant/emolients/moisturizers. For example, the friction coefficient of hydrated skin (through the action of moisturizing products) is higher than the friction coefficient of dry skin.The relationship between the friction coefficient and the Hi/Ho balance can be reversed in the presence of water and sebum on forehead, for example.     

Coefficient of friction: tribological studies in man – an overview

Background/purpose: Compared to other studies of skin, relatively few studies have focused on the friction of skin. This work reviews existing skin friction, emphasizing test apparatuses and parameters that have added to information regarding the friction coefficient. This review also outlines what factors are important to consider in future friction studies.
Methods: Past studies have utilized numerous designs for a test apparatus, including probe geometry and material, as well as various probe motions (rotational vs. linear). Most tests were performed in vivo ; a few were performed in vitro and on porcine skin.
Results: Differences in probe material, geometry and smoothness affect friction coefficient measurements. An increase in skin hydration, either through water or through moisturizer application, increases its friction coefficient; a decrease in skin hydration, either through clinical dermatitis or through alcohol addition, decreases the coefficient. Differences are present between anatomical sites. Conflicting results are found regarding age and no differences are apparent as a result of gender or race.
Conclusion: Skin friction appears to be dependent on several factors – such as age, anatomical site and skin hydration. The choice of the probe and the test apparatus also influence the measurement.     

Skin–textile friction and skin elasticity in young and aged persons

Background/purpose: The mechanical properties of human skin are known to change with ageing, rendering skin less resistant to friction and shear forces, as well as more vulnerable to wounds. Until now, only few and contradictory results on the age-dependent friction properties of skin have been reported. This study has investigated in detail the influence of age on the friction of human skin against textiles.
Methods: In vivo skin-friction measurements on a force plate were combined with skin analyses concerning elasticity, hydration, pH value and sebum content. Thirty-two young and 28 aged persons rubbed their volar forearm in a reciprocating motion against various textiles on the force plate, using defined normal loads and sliding velocities, representing clinically relevant contact conditions.
Results: Mean friction coefficients ranged from 0.30 ± 0.04 (polytetrafluoroethylene) to 0.43 ± 0.04 (cotton/polyester). No significant differences in the friction properties of skin were found between the age groups despite skin elasticity being significantly lower in the aged persons. Skin hydration was significantly higher in the elderly, whereas no significant differences were observed in either skin pH value or sebum content.
Conclusion: Adhesion is usually assumed to be the dominant factor in skin friction, but our observations imply that deformation is also an important factor in the friction of aged skin. In the elderly, lower skin elasticity and skin turgor are associated with more pronounced skin tissue displacements and greater shear forces during frictional contact, emphasizing the importance of friction reduction in wound-prevention programmes.     

Changes in function and morphology of normal human skin: evaluation using optical coherence tomography

BACKGROUND: Optical coherence tomography (OCT) is a noninvasive morphological method for investigating human skin. It allows high-resolution in vivo imaging of inflammatory skin diseases and tumours. Because it is a newly developed method, systematic studies on standardization and on evaluation of factors influencing the representation of the skin have not yet been performed. OBJECTIVES: In this study, normal human skin was treated with various external stimuli which induce changes of function and morphology. Changes in stratum corneum thickness as well as changes induced by pigmentation, oedema and erythema were investigated using OCT. METHODS: Healthy skin of human volunteers was treated with tape stripping, ultraviolet A irradiation, water, histamine, nicotinic acid and various ointments. RESULTS: In the tape stripping experiment, the thickness of the horny layer was quantified and monitored. Pigmentation increased the light attenuation of the tissue, whereas hydration and erythema led to a slight decrease of scattering. Topical treatment of the skin gave a nonspecific increase of penetration depth of the light due to the lower reflectivity of the surface. CONCLUSIONS: There are various physiological conditions which influence optical properties of the skin. These parameters should be considered when performing standardized OCT studies.     

Biophysical skin properties of grade 1 pressure ulcers and unaffected skin in spinal cord injured and able-bodied persons in the unloaded sacral region

Aim of the study

To examine biophysical skin properties in the sacral region in spinal cord injury (SCI) patients suffering from a grade 1 pressure ulcer (PU) defined as non-blanchable erythema (SCI/PU), SCI patients in the post-acute phase (SCI/PA) and able-bodied participants (CON). Also, for SCI/PU patients, both the affected skin and healthy skin close to the PU were examined.