Hydration characteristics of pathologic stratum corneum--evaluation of bound water

We measured in vitro the hygroscopicity and bound (non-freezing) water of various samples of pathologic horny layer obtained from the lesions of senile xerotic skin and psoriasis vulgaris and the normal horny layer from glabrous skin and plantar horny layer. The amount of water taken up by pathologic stratum corneum was much smaller than that by normal horny layer in an environment at a high relative humidity (RH). Tightly bound primary water to stratum corneum measured by Karl Fischer's method was about 5 mg/100 mg of dry stratum corneum in all the samples studied, while less tightly bound secondary water was much smaller in amount in pathologic stratum corneum than in the controls, i.e., 31.7 mg/100 mg dry scale from senile xerosis and 27.2 mg/100 mg dry psoriatic scale as compared with 38.2 mg/100 mg dry normal stratum corneum from glabrous skin and 37.3 mg/100 mg dry normal plantar stratum corneum. We believe that the low hygroscopicity of the pathologic stratum corneum is due to this smaller capacity for secondary bound water, which is responsible for the development of a dry scaly appearance even at high RH.     

【开放获取】皮肤干燥是通透屏障功能受损的表现吗？

【摘要】 有学者认为,皮肤干燥是表皮通透屏障功能受损的表现,但目前尚没有足够的证据证明这一观点。实际上,皮肤干燥是角质层含水量降低的表现。角质层含水量主要由角质层天然保湿因子的量决定,而表皮通透屏障功能则主要由角质层脂质的质和量以及结构蛋白决定。如果皮肤干燥是由表皮通透屏障功能降低所致,那么,角质层含水量应当与透皮失水率呈负相关性。但是研究表明,无论是正常人皮肤、鱼鳞病皮损或皮脂腺缺乏的小鼠皮肤,角质层含水量与透皮失水率均无负相关性。相反,有研究显示,人角质层含水量与透皮失水率呈正相关性。因此,皮肤干燥似乎不是表皮通透屏障功能受损的表现。     

The water content of the stratum corneum in patients with atopic dermatitis. Measurement with the Corneometer CM 420

The dry looking skin seen in many patients with atopic dermatitis reflects a defect in the epidermal barrier, the stratum corneum, as demonstrated by an increased transepidermal water loss (TEWL) and a decreased ability of the stratum corneum to bind water. The absolute amount of water within the stratum corneum is of importance both for barrier properties and for the clinical appearance of the skin. This water content was measured with a new instrument, the Corneometer CM 420, which takes advantage of the high dielectric constant of water. Forty patients with atopic dermatitis were studied--20 with dry skin and 20 with clinically normal skin on non-eczematous areas. The stratum corneum in dry skin was found to have a lower content of water than that in the clinically normal skin (p less than 0.01). Clinically normal skin in patients with atopic dermatitis did not differ significantly from normal control skin. An experiment was performed in vitro in an attempt to correlate the values obtained with the Corneometer to the absolute amount of water within the corneum.     

Effects of calcipotriol on stratum corneum barrier function, hydration and cell renewal in humans

Summary Calcipotriol. a vitamin D analogue utilized for psoriasis, has irritation as its most frequent reported adverse event. However, studies on its irritant properties in humans have produced conflicting data. This study evaluates the effect of calcipotriol on stratum corneum barrier function, hydration and cell turnover in healthy volunteers, compared with sodium lauryl sulphate (SLS) as a model irritant. Calcipotriol 0·005% ointment and 1% aqueous SLS solution were applied for 2 weeks (5 consecutive days weekly) on untreated and on dansyl-chloride-labelled skin. Irritant responses were documented by visual scoring and by measurement of the transepidermal water loss (TEWL) and stratum corneum hydration (electrical capacitance), until day 18 Stratum corneum turnover time (SCTT) was the time in days between staining (day 0) and the disappearance of dansyl fluorescence. SLS caused more erythema, scaling, and a significant TEWL increase for 18 days. In contrast, calcipotriol induced erythema, and slightly but significantly increased TEWL on day 11 only, as compared with the vehicle control (P<0·05) SLS, but not calcipotriol, caused skin dryness from day 4 to day 18. The shortest SCTT was obtained at SLS-exposed sites (11·2 ± 0·7 days: mean± SD). Calcipotriol significantly shortened SCTT (16.3 ± 1.1 days) when compared with its vehicle. Compared with the skin irritation induced by SLS, under these test conditions, calcipotriol is a far weaker irritant on normal human skin. In addition, calcipotriol accelerates stratum corneum turnover to a significantly greater extent than its vehicle.     

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。     

A method for predicting steady-state rate of skin penetration in vivo

A simple in vivo method was proposed for predicting the steady-state rate of penetration of drugs across the stratum corneum. Both the diffusion coefficient and the partition coefficient in the stratum corneum can be determined by the amounts of drug in the stratum corneum at two time intervals under transient conditions after transdermal drug application. The amount of drug entering the stratum corneum is determined by 20 strippings with an adhesive tape. The steady-state rate of penetration was then calculated for the thickness of the stratum corneum and the concentration of the donor solution. The steady-state rates of penetration of ascorbic acid and estradiol across hairless mouse skin were evaluated from this in vivo approach and compared with those obtained from in vitro penetration experiment using excised hairless mouse skin. The data confirmed that the proposed in vivo method can predict the steady-state rate of penetration of these drugs across the stratum corneum in normal skin.     

Stratum corneum chymotryptic enzyme: a proteinase which may be generally present in the stratum corneum and with a possible involvement in desquamation.

A chymotrypsin-like proteinase that may be involved in the desquamation process in plantar stratum corneum has recently been partially characterized. The aim of the present study was to elucidate whether a similar proteinase is also present in non-palmo-plantar stratum corneum. Stratum corneum was obtained by tape stripping of volar forearm skin after the skin surface had been painted with colourless nail varnish. The adherent tissue was released from the tape strips by acetone treatment, then extracted with diethyl ether and dried. Extracts of this acetone-ether powder were analyzed with respect to proteolytic activity by means of electrophoresis under non-reducing conditions in polyacrylamide gels containing sodium dodecyl sulphate and casein. The extracts were found to contain one major chymotrypsin-like proteinase with an apparent molecular weight of around 25 kDa, and several minor proteinases with trypsin-like activity. The 25 kDa proteinase was active at pH 5.5-8, and could be inhibited by aprotinin, chymostatin and zinc ion, but not by leupeptin. No difference could be found between the 25 kDa enzyme in forearm stratum corneum and the recently described chymotrypsin-like enzyme in dissociated plantar stratum corneum cells as regards electrophoretic mobility, pH dependency, and inhibitor profile. The fact that the enzyme could degrade casein at pH 5.5 and that it appears to be present in stratum corneum in general suggests that it may play a role in the desquamation process under in vivo conditions. The tentative name "stratum corneum chymotryptic enzyme" is proposed for this newly discovered proteinase.     

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.     

麻风患者愈后表皮某些生理功能障碍研究

目的：了解麻风愈后者其原受累及部位是否存在角质层生理功能障碍。方法：利用多功能皮肤生理仪对麻风患者痊愈后前臂原皮损处角质层含水量、酸碱度、透过皮肤水分丢失率及屏障功能的恢复速度进行测量。结果：与正常对照组相比,麻风愈后者原皮损处角质层含水量明显降低（P〈0．002）,以瘤型麻风患者降低幅度最大;皮肤表面的pH明显增高（P〈0．0001）,界线类偏结核型患者pH改变不甚明显;麻风愈后者原皮损处的基础表皮通透屏障功能好于正常人,以界线类偏瘤型患者水分丢失量降低最明显：麻风愈后者原皮损处表皮通透屏障功能的恢复速度无明显改变。结论：麻风患者痊愈后仍然有角质层生理功能障碍。     

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.     

Evidence that cell shedding from plantar stratum corneum in vitro involves endogenous proteolysis of the desmosomal protein desmoglein I.

We have recently described a process leading to a unipolar cell shedding from pieces of plantar stratum corneum incubated in vitro, which seems to be dependent on the activity of a serine proteinase. This process has been studied further. Electron microscopy studies suggest that cell dissociation is preceded by a degradation of the intercellular parts of desmosomes. An antiserum was raised against the transmembrane protein desmoglein I (DG I) of bovine desmosomes. In extracts of layers of plantar stratum corneum with strong intercellular cohesion, this antiserum reacted with a protein of the same apparent molecular weight as bovine DG I. In dissociated cells this DG I-like protein could not be detected; instead components with molecular weights lower than DG I which reacted with the antiserum were found. During incubation of pieces of plantar stratum corneum, under conditions leading to unipolar cell shedding, there was a progressive decrease in the amounts of the DG I-like protein, and the appearance of the lower molecular weight components with DG I-like immunoreactivity. This apparent degradation of the DG I-like protein was inhibited by aprotinin, chymostatin, and zinc ion, but not by leupeptin. The results suggest that proteolytic degradation of desmosomes may be an important part of the process leading to cell dissociation in plantar stratum corneum in vitro, and that desmosomes may play an important role in plantar stratum corneum cell cohesion.     

Sebaceous gland secretion is a major physiologic route of vitamin E delivery to skin

Skin plays an important part in the protection against oxidative stressors, such as ultraviolet radiation, ozone, and chemicals. This study was based on the observation that upper facial stratum corneum contained significantly higher levels of the antioxidant alpha-tocopherol than corresponding layers of arm stratum corneum. We hypothesized that the underlying mechanism involves sebaceous gland secretion of vitamin E. To test this, we examined in eight human volunteers: (i) stratum corneum levels and distribution profiles of vitamin E in sites with a different sebaceous gland density (arm versus cheek); (ii) whether vitamin E is a significant constituent of human sebum; and (iii) if there is a correlation between levels of vitamin E and squalene, a marker of sebum secretion, in skin surface lipids. Using standardized techniques for stratum corneum tape stripping and sebum collection, followed by high-performance liquid chromatography analysis of tocopherols and squalene, we found that: (i) the ratio of cheek versus upper arm alpha-tocopherol levels was 20 : 1 for the upper stratum corneum and decreased gradually with stratum corneum depth; (ii) vitamin E (alpha- and gamma-tocopherol forms) is a significant constituent of human sebum and is continuously secreted at cheek and forehead sites during a test period of 135 min; and (iii) vitamin E correlates well with levels of cosecreted squalene (r2 = 0.86, p < 0.001). In conclusion, sebaceous gland secretion is a relevant physiologic pathway for the delivery of vitamin E to upper layers of facial skin. This mechanism may serve to protect skin surface lipids and the upper stratum corneum from harmful oxidation.     

Changes in environmental humidity affect the water-holding property of the stratum corneum and its free amino acid content,and the expression of filaggrin in the epidermis of hairless mice

BACKGROUND: Seasonal changes affect the condition of skin and may trigger various cutaneous disorders. OBJECTIVE: To clarify the effects of the environmental humidity on the skin pathology, we studied the effects of the humidity on a water-holding function of the stratum corneum. METHODS: We evaluated the skin surface conductance, amino acid in the stratum corneum, and immunoreactivity of filaggrin of the epidermis of hairless mice kept in different environmental humidity. RESULTS: Skin surface conductance in the stratum corneum of hairless mice 3-7 days after transfer from a humid environment (>80% relative humidity) to a dry (<10% relative humidity) environment, was significantly lower than that of the mice transferred from a normal environment (relative humidity=40-70%) to a dry environment. The free amino acid content in the stratum corneum significantly decreased 24 h after we transferred the mice from a normal to a dry condition, then it recovered to the original level within 3 days, while the mice transferred from a humid to a dry condition showed a significantly lower amino acid content even 7 days after the transfer. No obvious change was observed in the relative composition of the major components of the free amino acids during the experiments. Immunoreactivity of filaggrin, which is the main precursor of free amino acids in the stratum corneum, also became faint in the epidermis of the mice transferred from a humid or normal to a dry environment. CONCLUSION: These results suggested that a drastic decrease in the environmental humidity reduced the total free amino acid generation and consequently induced skin surface dryness in the stratum corneum.     

Human stratum corneum adsorption of nickel salts. Investigation of depth profiles by tape stripping in vivo.

Sequential adhesive tape stripping was implemented to characterize the penetration of nickel salts in human stratum corneum. Exposure areas of the salts in methanol applied open on arm and back skin in low volume were stripped 20 times to the level of the glistening layer at intervals of 30 min to 24 h post-dosing, and the strips analyzed for metal content by inductively coupled plasma-atomic emission spectroscopy. In the case of nickel chloride, sulfate, nitrate and acetate, material left on the skin surface, the depth-penetration profiles in the stratum corneum, and the dosage unaccounted for suggest the following conclusions: (a) Up to 24 h, most of the nickel dose applied remains on the skin surface or is adsorbed in the uppermost layers of the stratum corneum. (b) At higher concentrations, incomplete material recovery becomes discernible; within 24 h, nickel salts thus appear to penetrate beyond the stratum corneum to a minor degree, possibly via the skin shunts. (c) While the concentration gradients of nickel adsorbed vary with counter ion, anatomical site, dose and exposure time, for all variables tested the depth profiles converge to non-detectable levels (< 20 ppb) towards the level of the glistening layer. A notable exception is nickel as nitrate, for which levels continue at low but constant levels (1% of dose) beyond the third stratum corneum strip, indicative of intercellular diffusion. (d) Differences in material recovered suggest that the stratum corneum on the arm is more penetrable to nickel than stratum corneum on the back. (e) The counter ion in nickel salts plays a major part in their diffusion into the stratum corneum, suggestive of ion pairing. Overall, the data point to all three avenues of skin penetration by nickel: intracellular, intercellular, and transappendageal.     

Desmoglein II-derived glycopeptides in human epidermis

Antisera raised against a major 78 kD glycopeptide from pig epidermis were used to identify desmoglein II-derived glycopeptides in the conA-binding material isolated from human epidermis. In whole CaCl2-separated epidermis the antiserum recognized conA-binding components with apparent Mr of 115, 100, 82, 68, 50, 48, and 46 kD. The 82, 68, 48, and 46 kD immunoreactive bands were present in normal stratum corneum and plantar callus. Psoriatic scales contained significantly more of the 82 kD components and less of the 48 and 46 kD bands. Psoriatic scales also contained a major 50 kD conA-binding component unrelated to keratins or desmoglein II. Proteolytic peptide mapping showed that the major immunoreactive bands in normal stratum corneum and plantar callus were also chemically related. The 82 to 46 kD immunoreactive glycopeptides in plantar callus coincided with the major coomassie blue stained bands and were homogeneous on two-dimensional gels suggesting that this tissue may be a valuable source of human desmoglein II-derived glycopeptides. An antiserum directed against the electrophoretically co-purified 48/46 kD glycopeptides from plantar callus recognized the 82 to 46 kD bands in immunoblotting. In indirect immunofluorescence of frozen skin sections this antiserum stained the surface of epidermal cells in the spinous and granular layers of the tissue. In immunogold labeling of paraformaldehyde-fixed skin sections affinity-purified antibodies stained intact desmosomes in spinous and granular cells and desmosomal remnants in the stratum corneum. The results are consistent with our hypothesis that desmoglein II undergoes limited cleavage to stable fragments during terminal differentiation. Proteolytic degradation appears to be incomplete in psoriatic epidermis.     

Neonatal skin maturation--vernix caseosa and free amino acids

Neonatal skin hydration decreases rapidly postnatally and then increases, indicating adaptive changes in stratum corneum water handling properties. Transition from high to low humidity at birth may initiate filaggrin proteolysis to free amino acids. Neonatal skin with vernix caseosa retained is more hydrated than skin with vernix removed. This study examines the potential roles of free amino acids and vernix in postnatal adaptation of infant stratum corneum in vivo. Specifically, the ontogeny of free amino acid generation in neonatal stratum corneum and the role of vernix caseosa in postnatal adaptation were examined using high performance liquid chromatography. Free amino acids were quantified for infant skin samples collected at (i) birth and 1 month and (ii) birth and 24 hours after vernix caseosa retention or removal and compared to neonatal foreskin, vernix caseosa, and adult stratum corneum using t-tests, analysis of variance, or univariate procedures. Free amino acids were extremely low at birth, significantly higher 1 month later but lower than in adults. Vernix caseosa retention led to significantly higher free amino acids 24 hours after birth compared to infants with vernix caseosa removed, and it paralleled the higher stratum corneum hydration of vernix caseosa-retained skin. Vernix caseosa contained free amino acids, with glutamic acid and histidine levels higher than in infants. Free amino acids in vernix caseosa-retained skin appear to originate from vernix caseosa. Free amino acids were lower in neonatal foreskin than adult forearm stratum corneum. Arginine was higher than citrulline at birth, but levels were comparable in older infants. The free amino acid increase at 1 month may be initiated by the humidity transition at birth and supports results in animals. The findings have implications for infant skin care practices.     

Existence of a lipid gradient in the upper stratum corneum and its possible biological significance

The internal stratum corneum lipid composition was investigated in relation to depth in vivo in healthy human volunteers by extraction following one, three or five strippings. Automated multiple development high-performance thin-layer chromatography (AMD-HPTLC) and gas chromatography (GC) followed by normalized principal component analysis showed a decrease in the amount of lipids extracted after one, three and five strippings. Between levels 0, 1, 3 and 5 the stratum corneum lipid composition showed an increase in phospholipids and cholesterol-3-sulphate at level 3, a decrease in ceramide, cholesterol and free fatty acids after level 1, and a slight decrease in sterol esters at level 3. Lipids extracted after three strippings displayed a characteristic composition with an increase in the proportion of phospholipids and cholesterol-3-sulphate. Free fatty acid analysis in relation to depth revealed a decrease in the amounts of C14:0, C16:0, C16:1, C18:0 and C18:1 between levels 1 and 5 and an increase in the C24:0. A decrease in the unsaturated/ saturated chain ratio with depth was also observed, reflecting a greater decrease in unsaturated than saturated free fatty acids. A decrease in the ratios of free fatty acids to cholesterol and free fatty acids to ceramides after three and five strippings, respectively, and previously reported results, confirm the importance of this level of stratum corneum lipids in skin barrier properties. Received: 12 March 1996     

Histologic differentiation of mechanical and non-mechanical keratoses of the sole

Histologic sections taken from nonmechanically induced keratoses of the sole due to either genetic causes, focal injury, or systemic disease are often misinterpreted as a simple callus tissue or hyperkeratoses. Normal plantar skin is hyperkeratotic because of its thick stratum corneum, often causing confusion with plantar callus, and at times being misinterpreted as keratotic nevoid keratoses of the soles. In some instances, however, features do exist that enable differentiation of one keratoses from another. If we study the natural history of mechanically induced keratoses of the soles, we realize that pressure-induced histologic change is not only limited to the epidermis, but involves the dermis and fat as well. In contrast, nonmechanical keratoses, even if located on weight-bearing surfaces, do not, as a rule, exhibit the epidermal, dermal, or fat changes seen in keratoses due to mechanical causes, such as abnormal foot function and structure. When interpreting histologie sections taken from keratotic lesions of the sole, certain considerations should be entertained. A determination should be made as to whether or not a diagnostic histology exists, e.g., epidermolytic hyperkeratoses. What is the relative state of the dermis? Is there scarring, eccrine sweat duct or blood vessel dilation, hypertrophied nerve, or vasculitis present? Is there underlying fibrous replacement of subcutaneous fat? The ratio between the stratum corneum and stratum malpighii must be determined and considered. Characteristic features seen in nonmechanically induced keratoses of the sole include a thick stratum corneum with normal underlying stratum malpighii; the stratum corneum is sometimes four to six times as thick as the stratum malpighii. The malpighian layer is normal and shows no signs of hyperplasia. The dermis also remains normal.Few other plantar keratoses exhibit this picture, and experience dictates that the only obstacle in identifying nonmechanical keratoses is in their differentiation from pressure-induced keratoses, e.g., corns and calluses.     

Human hematoxylin-stainable protein of keratohyalin granules origin. I. Extraction and purification

A human hematoxylin-stainable protein (HSP) was extracted from the massive stratum corneum of epidermal cysts. This protein was purified in two steps; first, through preparative isoelectric focusing, and, second, by affinity column chromatography bound with the specific, monoclonal antibody to keratohyalin granules (Ted-H-1). In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified HSP consisted of two proteins (70 and 62 kilodaltons [kd]), but only the 62-kd protein was detected in the 15,000 g supernatant fraction of the extract using the immunoblotting technique. The amino acid composition of the purified HSP included 30% glycine, 15% serine, 12% glutamic acid, and 4% ornithine, but only 2.3% histidine. Using the indirect immunofluorescent technique, observation showed that the monoclonal antibody, Ted-H-1, to the HSP, formed as a result of the partially purified antigen, was located in three places: 1) the keratohyalin granules; 2) in the cell membrane region of the lower part of the stratum corneum of the skin samples (forearm, cheek, and back); and 3) the keratohyalin granules in the follicular epithelium and on the trichohyalin granules. Reaction product was not seen in either the acrosyringium or in the plantar epidermis. As two positively reacted proteins with the Ted-H-1 were detected in the Tris-HCl extract from the plantar stratum corneum by the immunoblotting assay, however, the above negative result in the indirect immunofluorescent studies may be due to the masking of the antigenic site of keratohyalin granules in vivo. This hematoxylin-stainable protein was synthesized as one component of the keratohyalin granules in the stratum granulosum and may have been transferred to the stratum corneum cell membrane region.     

Pitted keratolysis

Pitted keratolysis is a skin disorder that affects the stratum corneum of the plantar surface and is caused by Gram-positive bacteria. A 30-year-old male presented with small punched-out lesions on the plantar surface. A superficial shaving was carried out for scanning electron microscopy. Hypokeratosis was noted on the plantar skin and in the acrosyringium, where the normal elimination of corneocytes was not seen. At higher magnification (x 3,500) bacteria were easily found on the surface and the described transversal bacterial septation was observed.