Effect of non-enzymatic glycosylation and heating on browning of human stratum corneum and nail.

The purpose of the present study was to examine the effect of non-enzymatic glycosylation and subsequent heating on the browning of the plantar stratum corneum and the finger-nail, and to elucidate the pathogenesis of the yellow skin and the yellow nail seen in diabetic subjects. We incubated stratum corneum and nail from non-diabetics in 0 (control), 10 (only nail), 20 (only nail), 100 and 250 mM glucose buffer at 37 degrees C for 5 days. These glycosylated samples were dialysed against distilled water for 96 h. Distilled water was changed every 24 h. Then samples were dried for 24 h. The extent of non-enzymatic glycosylation was measured by furosine content. Each 5 mg of sample was hydrolysed by 6 N HCl and processed for measurement of furosine by high-performance liquid chromatography. The rest of each sample was stored at 37, 42 (only nail), 47 and 52 degrees C for 14 days. Browning of the stratum corneum was assessed macroscopically, and that of the nail by spectrophotometry. Based on their spectrophotometric reflectances. Munsell's scores (H = hue score, V = lightness score, C = saturation score) and (H + C)/V were calculated for objective evaluation of browning. Incubation of the stratum corneum and nail with glucose buffer increased their non-enzymatic glycosylation (furosine) dose dependently. Macroscopically, the browning of the stratum corneum was enhanced in proportion to the glucose concentration and storage temperature. However, samples incubated in 10 and 20 mM glucose and stored at 42 degrees C did not show visible browning. Munsell's score of the nail samples treated by glycosylation and heating showed increased hue and saturation but reduced lightness. (H + C)/V values of these nail samples were significantly higher than those of the control. We could not detect any fluorescence with Wood light in the browned samples. The present in vitro study demonstrated that the browning of the stratum corneum and the nail depended on the extent of both non-enzymatic glycosylation and storage temperature. We suggested a hypothesis that the non-enzymatic glycosylation and the storage temperature of the stratum corneum and the nail might be a contributory factor in the development of yellow skin and yellow nail in diabetic patients.     

Heterogeneity of epidermal prekeratin and keratin between sole and body skin in humans

Recently, heterogeneity of stratum corneum keratin (α-fibrous protein) in various anatomic sites has been described in humans as well as cows and rats. In order to study this heterogeneity more clearly in humans, we compared acid soluble (citrate buffer at pH 2.65) prekeratin, acid insoluble (8 M urea-2-mercaptoethanol soluble) living cell keratin, and stratum corneum keratin from sole and body (nonsole-nonpalm) skin using SDS-polyacrylamide gel electrophoresis (PAGE), amino acid analysis, and immunological analyses. In prekeratin, no differences were seen between sole and body by SDS-PAGE. Prekeratins from the two sources showed a 4-band pattern with molecular weights of 55,000, 59,000, 62,000 and 69,000. In living cell keratin, the 69,000 band disappeared and a 49,000 band appeared in sole, but not in body epidermis. In stratum corneum keratin, a distinct difference was seen between sole and body skin. The sole stratum corneum keratin showed a 3-band pattern (55,000, 59,000 and 62,000 mw) while that of body showed a two-band pattern (59,000 and 66,000 mw). Despite the heterogeneity of the SDS-PAGE profiles, no significant differences were seen in amino acid composition amongst these specimens. Immunologically, using double diffusion, antiserum against stratum corneum keratin from the sole principally produced two precipitin lines against the same keratin of sole origin and one precipitin line against prekeratin, living cell keratin, and stratum corneum keratin of body origin. This precipitin line fused with one of the two precipitin lines produced between antiserum and the sole stratum corneum keratin. These results indicate that anatomical-site heterogeneity in α-fibrous protein of human epidermis does not exist at the acid-soluble prekeratin level, but does at the acid-insoluble keratin level of living cell layer and stratum corneum when examined by SDS-PAGE, and that some, but not all, keratin antigens are immunologically common between sole and body.     

Comparing skin characteristics and molecular markers of xerotic foot skin between diabetic and non-diabetic subjects: An exploratory study

BackgroundXerosis cutis of the feet is one of the most common skin conditions among type 2 diabetics. Whether skin dryness among diabetic patients is different from ‘general’ skin dryness is unclear. The overall aim was to compare the structure, function and molecular markers of dry and cracked foot skin between diabetics and non-diabetics.MethodsThe foot skin of 40 diabetics and 20 non-diabetics was evaluated. A clinical assessment of skin dryness was performed and transepidermal water loss, stratum corneum hydration, skin surface pH, epidermal thickness, skin roughness, elasticity and structural stiffness were measured. Ceramides, natural moisturizing factors, histamines, proteins and molecular markers of oxidative stress were analyzed based on a non-invasive sampling method for collection of surface biomarkers.ResultsThe mean number of superficial fissures in the diabetic group was nearly three times higher than in the non-diabetic group (11.0 (SD 6.2) vs. 3.9 (SD 4.2)). The skin stiffness was higher in the diabetic group and the values of almost all molecular markers showed considerably higher values compared to non-diabetics. Malondialdehyde and glutathione were lower in the diabetic sample.ConclusionsThe high number of superficial fissures may be based on an increased stiffness of dry diabetic foot skin combined with different concentrations of molecular markers in the stratum corneum compared to dry foot skin of non-diabetics.     

Fibrous proteins of trichilemma-oid epidermal keratinization without keratohyalin granules formation--electron microscopic and electrophoretic studies

Interactions between the histidine-rich protein of keratohyalin granules and keratin fibers were investigated. Keratin fibers of the stratum corneum from sole skins of both normal persons (NP) and those with hereditary palmoplantar keratoderma (HPPK) were examined. HPPK samples showed trichilemma-oid keratinization except at the sweat duct. Epidermis around the sweat duct showed stratum granulosum formation. The keratin pattern was lost in the non-sweat duct region; any changes in the size and distribution-pattern of keratin fibers were, however, observed by electron microscopy. In sodium dodecylsufate polyacrylamide gel electrophoresis (SDS-PAGE), keratin fibers in the HPPK stratum corneum, from both non-sweat duct and sweat duct regions, and in the stratum corneum of the sole lesion of the HPPK's mother, lacked 57kd subunits, but the electrophoretic profiles of other keratin subunits were identical to those from NP samples. It was concluded that the lack of histidine-rich protein formation causes no change in keratin fibers themselves either under electron microscopy or in SDS-PAGE. The absence of a 57kd subunit keratin fiber may have been caused by abnormalities in the production or degeneration processes of keratin fibers of the HPPK epidermis.     

Glycosylated proteins of stratum corneum, nail and hair in diabetes mellitus: correlation with cutaneous manifestations

Nonenzymatic glycosylation of protein may play some role in the development of diabetic complications. To study the association of nonenzymatically glycosylated protein in keratinized tissues with the prevalence of cutaneous manifestations frequently observed in diabetics, we measured furosine values of stratum corneum, nail and hair from 61 diabetics and assessed their cutaneous manifestations. The manifestation most frequently found in this study was 10 cases of pigmented pretibial patches. We did not detect significant correlations between the prevalence of any cutaneous manifestations and furosine values of any keratinized tissues. However, 11 of the 17 patients with yellow nail showed high nail furosine values. Our data suggest that nonenzymatically glycosylated protein levels in the keratinized tissues do not correlate with the prevalence of cutaneous manifestations in diabetics, but do not exclude a role in the formation of yellow nail.     

Autonomic and sensory nerve function in diabetic foot ulceration

Peripheral sensory and autonomic nerve dysfunction are thought to be crucial factors in the pathogenesis of diabetic foot ulceration. However, their relative importance is not known. In this study we have compared peripheral sensory nerve function and cardiac autonomic reflexes in 51 diabetics with a history of foot ulceration and 480 diabetic control subjects. In the diabetics with ulceration ankle reflexes were absent or impaired and vibration perception threshold reduced in 96.1% and 82.4%, respectively, compared with 40.8% and 25.8%, respectively, in control subjects (P less than 0.001). Cardiac autonomic tests were abnormal more frequently in the diabetics with ulceration and an autonomic score derived from four tests was abnormal in 62.8% of those with ulceration compared with 13.5% of those without ulceration (P less than 0.001). Discriminant analysis of the two groups of diabetes showed that an abnormal autonomic score was the best predictor of foot ulceration in diabetic patients.     

大连汉族414名正常人皮肤摩擦系数检测

目的 探讨大连汉族正常人皮肤摩擦系数是否与性别和年龄有关.方法 414名汉族志愿者参加本项研究,年龄2个月至79岁,男187例,女227例;平均年龄(35.80±1.33)岁.根据生长发育期将其分为3组:0～12岁为青春期前组;20～40岁为青壮年组;60～80岁为老年组.利用Courage-Khazaka多功能皮肤生理仪Frictiometer(R) FR 770 and Corneometer(R) CM 825探头分别测量不同部位皮肤摩擦系数和角质层的含水量(电容).结果 在男性,除老年组前额部位皮肤摩擦系数明显低于手背部位外(P＜0.05),在其他各年龄组中,各部位之间皮肤摩擦系数差异无统计学意义;而在女性,除青壮年组前额部位的皮肤摩擦系数明显低于手背和眼外眦部位外(P＜0.001),在其他各年龄组中,各部位之间皮肤摩擦系数差异也无统计学意义.在男性,同一部位各年龄组之间皮肤摩擦系数差异无统计学意义;然而在女性的前额部位,老年的皮肤摩擦系数明显大于青春期前和青壮年(P值均＜0.01);在女性的眼外眦和手背部位,青壮年的皮肤摩擦系数明显大于青春期前和老年(P值均＜0.01).除青壮年女性手背和眼外眦部位的皮肤摩擦系数明显大于男性外(P分别＜0.05和0.001),在其他各年龄组和各部位中,男女间皮肤摩擦系数差异无统计学意义.在青壮年男性,各部位皮肤摩擦系数与角质层的含水量呈正相关性(前额r=0.6342,P＜0.0001;眼外眦r=0.4501,P＜0.001;手背r=0.3627,P＜0.01);而在女性,仅老年前额和眼外眦的皮肤摩擦系数与角质层含水量呈正相关性(前额r=0.2797,P＜0.05;眼外眦r=0.486,P＜0.001).结论 汉族正常人皮肤摩擦系数与性别、年龄、部位及角质层含水量有关.

Abstract：

Objective To determine whether skin friction coefficient (SFC) is associated with gender and age in a normal Chinese Han population. Methods A total of 414 Chinese Han subjects including 187males and 227 females, who were aged from 0.15 to 79 years (mean age: 35.80 ± 1.33 years), were enrolled in this study. According to human development stages, subjects were divided into pre-puberty group (aged 0 - 12years), young group (aged 20 - 40 years) and old group (aged 60 - 80 years). SFC and stratum corneum capacitance were measured with A Frictiometer(R) FR 770 and Corneometer(R) CM 825 (C&K MPA 5), respectively,on the dorsal hand, forehead, as well as canthus. Results SFC was higher on the dorsal hand than on the forehead in old males (P ＜ 0.05 ), and higher on the dorsal hand and canthus than on the forehead in young females (both P ＜ 0.001 ), while no significant difference was observed between the three measured sites in other groups of females or males (all P ＞ 0.05 ). In males, SFC on each measured site was similar among the three groups. In contrast, SFC was significantly higher on the forehead of females in aged than in young and pre-puberty groups (both P ＜ 0.01 ), and on the canthus and dorsal hand of females in young than in pre-puberty and aged groups (all P ＜ 0.01 ). The SFC on the canthus and dorsal hands of young females was higher than that of age-matched males (P ＜ 0.0001 and 0.05, respectively). A positive correlation was found between SFC and stratum corneum hydration in young males (foreahead: r = 0.6342, P ＜ 0.0001; canthus: r = 0.4501, P ＜0.001; dorsal hands: r = 0.3627, P ＜ 0.01 ). Moreover, SFC on the forehead (r = 0.2797, P ＜ 0.05) and canthus (r = 0.486, P ＜ 0.001 ) was also positively correlated with stratum corneum hydration in old females.Conclusion Skin friction coefficient varies with age, gender, body sites and stratum comeum hydration in normal Han populations.     

Glycosylated proteins of skin, nail and hair: application as an index for long-term control of diabetes mellitus

The purpose of the present study was to compare the degrees of nonenzymatically glycosylated proteins in the skin (stratum corneum), the nail, the hair, and hemoglobin obtained simultaneously from the same subject and to evaluate the most useful sample for management of diabetic complications. Fifty-one diabetic patients and 20 control patients were examined, utilizing furosine determination. Furosine value of the skin in diabetics was 2.14 +/- 1.70%, whereas that in controls was 1.65 +/- 0.47%. Furosine value of the nail in diabetics was 6.67 +/- 3.30%, whereas that in controls was 4.16 +/- 1.62%. Furosine value of the hair in diabetics was 1.30 +/- 1.11%, whereas that in controls was 1.29 +/- 1.71%. Close correlations were detected between HbA1 (glycosylated hemoglobin) and furosine of the nail (r = 0.58, p less than 0.001), HbA1 and furosine of the skin (r = 0.48, p less than 0.001), and HbA1 and furosine of the hair (r = 0.43, p less than 0.01); however, poor correlations were found between furosine of the hair and the skin (r = 0.35, p less than 0.05) and furosine of the nail and the hair (r = 0.33, p less than 0.05). Furosine of the nail was significantly correlated with the FBS (fasting blood sugar) of the same time, previous 6, and previous 12 months. Furosine value of the nail, we believe, is the most useful indicator for evaluating long term control of diabetics and may provide useful information for management of diabetic complications.     

两种维生素E乳剂保湿性的比较

目的了解维生素E乳喷雾剂的保湿效果及患者的依从性,与对照乳液比较,评价其优劣。方法共观察40例受试者,采用自身对照试验,分别在基线、2周后、4周后检测靶部位皮肤的角质层含水量、经表皮失水率、pH值,受试者主观评价。结果全部受试者均完成了试验,未发生不良反应。2组之间靶部位的角质层含水量、经表皮失水率、pH值在0,2,4周时差异均无统计学意义（P〉0．05）。2组靶部位的角质层含水量在2周及4周后均较基线时显著升高,差异有统计学意义（P〈0．01）;而表皮失水率和pH值较基线时无明显变化,差异无统计学意义（P〉0．05）。多数受试者（67．5％）认为喷雾剂优于乳膏剂。结论维生素E乳喷雾剂保湿效果好,与对照乳液的保湿效果相当,优点是清爽、无香味。     

大鼠皮肤角质层对荧光素钠脂质体透皮吸收的影响

目的 探讨大鼠皮肤角质层对荧光素钠脂质体透皮吸收的影响。方法 采用Scotch胶带剥脱皮肤角质层,利用荧光光度计、Franz扩散池和荧光显微镜研究皮肤角质层和活性层中荧光素钠的含量;观察皮肤剥脱角质层后荧光素钠脂质体透皮吸收能力的变化和荧光素钠在皮肤中的分布。结果 应用脂质体后皮肤各层荧光素钠的分布量均较相应溶液和凝胶作用后增加(P<0.01);荧光素钠在皮肤各层的分布比例发生了变化;剥脱角质层后脂质体荧光素钠混悬液和荧光素钠溶液各时间点累积透皮浓度相比较,差异无显著性(P>0.05);脂质体荧光素钠凝胶和荧光素钠凝胶相比较,各时间段累积透皮浓度差异无显著性(P>0.05)。结论 脂质体能增加皮肤各层的荧光素钠含量,并能够改变皮肤角质层和去角质层皮肤之间的荧光素钠比例。剥脱角质层后脂质体制剂透皮量显著增加,与相应的普通制剂相比差异无显著性;剥脱角质层后脂质体制剂的毛囊扩散途径不发生改变。     

ATR-FTIR技术在面部敏感性皮肤角质层成分分析中的应用研究

【摘要】 目的 利用衰减全反射傅里叶变化红外光谱仪（ATR-FTIR）分析敏感性皮肤与正常皮肤角质层成分的差异,探讨该技术在敏感性皮肤发生机制研究中的应用价值。方法 自2018年12月至2019年2月,招募在上海市居住 ≥ 6年的148例志愿者,通过问卷调查、乳酸刺痛试验和辣椒素试验,将受试者分为正常皮肤组和敏感性皮肤组;同时,记录乳酸刺痛试验和辣椒素试验中受试者的总刺痛评分和总灼痛评分。应用ATR-FTIR检测角质层成分,包括天然保湿因子（NMF）、角质层脂质、游离脂肪酸（FFA）和β/α比值;同时应用其他无创技术测量经表皮失水率（TEWL）、角质层含水量、角质层脂质、皮肤pH值和3种周围感觉神经纤维的电流感觉阈值和浅表皮肤血流灌注量等皮肤生理参数。分析角质层成分与总刺痛评分和总灼痛评分的Spearman相关系数,以及与皮肤生理参数的Pearson相关系数。结果 73例志愿者完成全部试验,其中敏感性皮肤组34例,男15例,女19例,年龄（41.8 ± 8.9）岁;正常皮肤组39例,男19例,女20例,年龄（42.8 ± 9.4）岁。敏感性皮肤组和正常皮肤组角质层NMF分别为30.90 ± 7.38、37.01 ± 8.77（t = 3.193,P < 0.01）,FFA分别为14.90 ± 6.75和20.45 ± 11.76（t = 2.422,P < 0.05）,β/α值分别为3.17 ± 1.03和2.67 ± 0.56（t = -2.595,P < 0.05）,角质层脂质两组差异无统计学意义（t = 1.458,P > 0.05）。皮肤生理参数中,敏感性皮肤组TEWL显著高于正常皮肤组（t = -3.496,P < 0.001）,而5 Hz电流感觉阈值和表皮致密度显著低于正常皮肤组（P < 0.05）,角质层脂质差异无统计学意义（P > 0.05）。相关分析显示,NMF、FFA和β/α与TEWL（r值分别为-0.405、-0.562、0.503,均P < 0.01）和总刺痛评分（rs值分别为-0.401、-0.285、0.316,P < 0.01或0.05）均呈良好的相关性,同时,表皮致密度与NMF（r = 0.402,P < 0.01）和β/α比值（r = -0.369,P < 0.05）也呈良好的相关性。但NMF、FFA和β/α与角质层脂质、3种感觉神经纤维的电流感觉阈值、浅表皮肤血流灌注量及表皮厚度之间均无相关性（均P > 0.05）。结论 敏感性皮肤与正常皮肤角质层NMF、FFA和β/α存在显著差异,且NMF、FFA和β/α与部分角质层屏障功能生理参数之间具有良好的相关性。因此,ATR-FTIR是一种有效评价敏感性皮肤屏障功能的手段。     

Characteristics of the epidermis and stratum corneum of hairless mice with experimentally induced diabetes mellitus

Diabetes mellitus induces many pathophysiologic changes in the skin. Even so, dermatologists still lack an animal model of diabetes that enables the direct evaluation of the various functional properties of the skin. Our group induced two types of an experimental type 1 diabetes model in hairless mice by administering either streptozotocin or alloxan, in order to examine the properties of the stratum corneum and epidermis of these animals. The plasma glucose concentrations of the mice at 3 wk after their i.v. injection were significantly higher than those of control mice (streptozotocin, 3.2-fold; alloxan, 3.7-fold). The stratum corneum water content was significantly reduced in both types of diabetic mice, whereas the transepidermal water loss remained unchanged. The amino acid content with normal epidermal profilaggrin processing was either normal or elevated in the stratum corneum of the streptozotocin-treated mice. In contrast, the stratum corneum triglyceride content in the streptozotocin-treated mice was significantly lower than the control level, even though the levels of ceramides, cholesterols, and fatty acids in the stratum corneum were all higher than the control levels. The streptozotocin-treated group also exhibited decreases in basal cell proliferation and epidermal DNA content linked with an increase in the number of corneocyte layers in the stratum corneum, suggesting that the rates of epidermal and stratum corneum turnover were slower in the streptozotocin-treated animals than in the normal controls. In contrast, there were no remarkable changes in any of the epidermal differentiation marker proteins examined. This finding in diabetic mice, namely, reduction in both the epidermal proliferation and stratum corneum water content without any accompanying impairment in the stratum corneum barrier function, is similar to that found in aged human skin. Our new animal model of diabetes will be useful for the study of diabetic dermopathy as well as the mechanisms of stratum corneum moisturization.     

Normal ultrastructure, but altered stratum corneum lipid and protein composition in a mouse model for epidermolytic hyperkeratosis.

Recently, we established keratin 10-deficient mice, serving as a model for the hyperkeratotic skin disorder epidermolytic hyperkeratosis. The considerable ichthyosis in these mice suggested alterations in terminal differentiation and in the formation of a functional epidermal barrier. Here, we report on the ultrastructural organization and composition of the stratum corneum lipids and on the expression of two major cornified envelope proteins. Electron microscopy of ruthenium tetroxide postfixed skin samples demonstrated a normal extrusion and morphology of lamellar bodies as well as the formation of bona fide lamellar layers in neonatal keratin 10-deficient mice. When we studied the composition of the major stratum corneum lipids, however, we found significant changes. Most importantly, the analysis of ceramide subpopulations revealed that the total amount of ceramide 2 was elevated in keratin 10-deficient mice, whereas ceramides 1, 3, 4, and 5 were decreased among total stratum corneum lipids. The amount of the ceramide precursors sphingomyelin and glucosylceramide was reduced in the stratum corneum without accompanying changes in the mRNA coding for acid sphingomyelinase. Notably, we found an increased mRNA and protein content for involucrin in neonatal keratin 10-deficient mice, whereas the expression of loricrin was not changed. Our data demonstrate that, although the formation of lipid layers in the stratum corneum appeared to be normal, its lipid composition is significantly altered in keratin 10-deficient mice.     

Haematoxylin stainable epidermal protein of the newborn rat. III. The change of the tissue reactivity to the antibody at various periods of growth

A polyclonal antibody elicited by a newly purified haematoxylin stainable protein (HSP) from newborn rat epidermis by Superose 12 column chromatography and Mono Q anion-exchange column chromatography showed localization in the cell membrane region of the stratum corneum cells of the flank skin and the foot pad skin of newborn rats, but not of adult rats in indirect immunofluorescent studies. In addition, although the stratum corneum of neither the fetal flank nor the foot pad skin (20th day of gestation) reacted with the antibody, both of them became positive shortly after birth (5 hours). However, the positive areas in the stratum corneum of the foot pad skin gradually moved to the upper part. Only the upper one third was positive at the 15th day after birth and the entire stratum corneum finally became negative in the adult. By immunoblotting technique, antigenic materials were detected in the fetal flank and foot pad skins, and in the adult foot pad skin, but not in the flank skin of adults. In immunofluorescent studies, neither the cornified nor non-cornified epithelia of the oral membrane, tongue, esophagus, trachea or bladder of the newborn rats (3-days old) reacted with this antibody. In studies of the reactivity of the stratum corneum of the other species, the outer one third of the stratum corneum of the flank skin of newborn mice positively reacted. However, the fluorescence was not membrane-located, but rather diffuse. Newborn guinea pig epidermis showed no positive reaction. The epidermis of adult mice, guinea pigs, dogs and humans showed no reaction with this antibody.     

Study of hydration of stratum corneum in leprosy

The study of hydration power of stratum corneum of lesions show highly significant poor water-uptake at low temperatures (p less than 0.001), a defect not recorded after removal of water soluble fractions. Secondly, the lesions show significant poor water-diffusive power (p less than 0.001). The findings suggest a qualitative alteration in the stratum corneum of leprosy patients, probably in its water-soluble protein fraction.     

Isolation and characterization of proteinase from Candida albicans: substrate specificity

Candida albicans was able to produce a keratinolytic proteinase (KPase) when cultivated in a medium containing human stratum corneum as a nitrogen source. The KPase was purified to 108.5-fold by ion-exchange chromatography and gel filtration. The molecular weight of the enzyme was estimated to be 42,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration through Sephacryl S-200, while the isoelectric point was determined to be at pH 4.5. The enzyme had an optimum pH of 4.0 and was "inactive" below pH 2.5 and above pH 6.0. The activity of KPase after preincubation at various temperatures was stable up to 50 degrees C. The keratinolytic activity was not affected by the addition of nonionic detergents and divalent cations. The enzyme was a glycoprotein and contained a high content of aspartic acid residues (172/1000). Pepstatin and chymostatin inhibited the activity in a dose-dependent manner; however, neither the other group specific inhibitors tested nor the pepsin specific inhibitors, DAN or EPNP, showed any effect on the enzyme. From these inhibitory profiles, this enzyme was determined to be a carboxyl proteinase such as cathepsin D. Among the various substrates for proteolytic enzymes, KPase digested human stratum corneum as much as albumin and hemoglobin. In the three fractions (water soluble, keratin filamentous, and membranous) prepared from human stratum corneum, the keratin filamentous fraction was more susceptible to degradation by KPase than the other two fractions were. KPase also digested much less human fingernail (13%) than human stratum corneum, but did not show any signs of there being any digestion of human scalp hair. These studies suggest that KPase from C. albicans may play an important role in superficial infection by affecting the human stratum corneum of the skin and nail.     

Keratolytic activity of microemulsions

OBJECTIVE: To compare the keratolytic activities of a drug-free hydrophilic microemulsion (ME) and a drug-free lipophilic ME with water, and with regard to the hydrophilic ME also with a 5% salicylic acid gel on the sole of the foot. METHODS: Twenty healthy volunteers had their plantar forefoot, midfoot, and rearfoot stratum corneum blackened with silver nitrate and a photographic developer, and a chromameter was used to determine the extent of removal of this black dye by a* value and L value measurement at 24 and 48 h. RESULTS: Both drug-free MEs produced significantly greater increases in a* value and L value than water, and the hydrophilic ME was also more effective than 5% salicylic acid gel. CONCLUSION: The irritating effect of MEs is rather negligible on the sole of the foot because of the thick plantar stratum corneum. Both MEs therefore appear suitable for the elimination or prevention of plantar desquamative and hyperkeratotic skin changes.     

Microfabrication of individual 200 microm diameter transdermal microconduits using high voltage pulsing in salicylic acid and benzoic acid

We describe an extension of semiconductor fabrication methods that creates individual approximately 200 microm diameter aqueous pathways through human stratum corneum at predetermined sites. Our hypothesis is that spatially localized electroporation of the multilamellar lipid bilayer membranes provides rapid delivery of salicylic acid to the keratin within corneocytes, leading to localized keratin disruption and then to a microconduit. A microconduit penetrating the isolated stratum corneum supports a volumetric flow of order 0.01 ml per s with a pressure difference of only 0.01 atm (about 10(2) Pa). This study provides a method for rapidly microengineering a pathway in the skin to interface future devices for transdermal drug delivery and sampling of biologically relevant fluids.     

Oriented structure in human stratum corneum revealed by X-ray diffraction

Various types of human stratum corneum (sheets or callus) were exposed, in parallel and perpendicular geometry, to the high flux of X rays produced by a synchrotron radiation source. Under these conditions, very clear and rich diffraction patterns, corresponding to the supramolecular organization of stratum corneum proteins and lipids, were obtained. The comparative study of normal or delipidized stratum corneum sheets and membrane couplets allows one to attribute certain diffraction features to lipids. Our results in the 3-7-nm range show two different distances for lipid bilayers. Concerning the protein nature of normal stratum corneum, the results show that keratin would occur in the beta form, whereas for callus it is in the alpha form. Indeed, normal stratum corneum sheets never display the 0.514-nm characteristic of alpha keratin. This result means that the supramolecular organization of keratin could depend on the keratinization process. Finally, our studies also confirm the presence of a still-unknown protein component existing in the beta form that would be located either inside the corneocytes or in some dilatated zones of the intercellular spaces.     

The influence of stratum corneum hydration on body fat determination by bioelectrical impedance analysis

Background/aims: Bioelectrical impedance analysis (BIA) is used for the estimation of the amount of body fat. We evaluated the influence of the stratum corneum hydration at the contact areas used for BIA on the body fat estimation. Methods: Stratum corneum hydration was measured at the sole of the right foot and the palm of the right hand before and after contact with the Tanita Body Composition Analyzer TBF 410^® and the Omron Body Fat Analyzer^®, (n=128 females and 126 males), respectively. Changes in stratum corneum hydration during the contact time were calculated (ΔHYD). As a gold standard for body fat estimation, the underwater weighing method (UWW) was used and the deviation of this standard was calculated for the Tanita (DT) and the Omron (DO) measurement. Results: During contact with the Tanita, stratum corneum hydration increased significantly at the foot. Neither stratum corneum hydration measured at the respective contact sites before BIA nor ΔHYD at the respective skin sites was related to DT or with DO. Conclusion: The BIA measuring procedure using the Tanita instrument leads to an occlusive effect at the contact site. BIA for the determination of body composition is not influenced by stratum corneum hydration.