Epidermal lipids

From the time an epidermal cell leaves the basal layer to the time it is desquamated, the cell lipids change dramatically, both qualitatively and quantitatively. The most abundant lipid class in basal cells is phospholipid with the remaining lipid being accounted for by roughly equal proportions of cholesterol, non-esterified fatty acid, triacylglycerol and glycolipid: minor components include cholesteryl esters and ceramide. In contrast, approximately half of the lipid in a desquamated cell consists of ceramide, with the remainder consisting largely of cholesterol and non-esterified fatty acid. Immediately before desquamation, small concentrations of cholesteryl sulphate and glycolipid have been found and there is evidence that these polar lipids are important components of the water barrier and also contribute towards the physical integrity of the lower part of the stratum corneum. The change in lipid content as cornification proceeds is no less dramatic than the change in lipid composition. A basal cell contains about 10 pg lipid, whereas a desquamated stratum corneum cell contains approximately six times this amount. The change in lipid composition of a cell undergoing cornification results, therefore, largely from de novo synthesis of lipid, especially cholesterol, non-esterified fatty acid and ceramide.
Les lipides de l'épiderme     

Follicular development and morphological changes in the vaginal epithelium during the estrous cycle of Galea spixii

The current study aimed to determine if characteristics observed in vaginal cytology during the estrous cycle of female SYT cavies corresponded with proliferation of the vaginal epithelium, characterized by proliferating cell nuclear antigen (PCNA) immunolocalization, and with follicular development at different phases of the estrous cycle. After determining estrous cycle phases by vaginal cytology, females were euthanized at metestrus, diestrus, proestrus, and estrus. Histological study of the vaginal epithelium and ovary were then performed. Immunohistochemistry for PCNA in vaginal tissue at each cycle phase was also performed. Superficial cornified cells and early post‐ovulatory follicles were found at estrus. Few nuclei below the enucleate superficial cells were immunoreactive to PCNA. At metestrus, the vaginal epithelium underwent desquamation and lost the superficial cornified cells; basal and intermediate cells appeared, and the post‐ovulatory follicle formed an early corpus luteum. No PCNA immunoreactivity was observed. At diestrus, the corpus luteum was developed, and the vaginal epithelium contained basal and intermediate cells. There was PCNA immunoreactivity in the cellular nucleus in the germinative stratum of the epithelium. Because of the growth and maturation of ovarian follicles, the vaginal epithelium suffered intense proliferation at proestrus. Vaginal cytology revealed large intermediate cells and nucleated and enucleated superficial cornified cells. In the ovary, mature follicles were present. More apparent immunoreactivity of PCNA in the germinative layer was found. In summary, we inferred that vaginal exfoliative findings matched the proliferation process of the vaginal epithelium. PCNA immunolocalization occurred as well as corresponding follicular development in the ovaries.     

中厚板轧制用工作辊剥落的类型及其原因分析

介绍了在中厚板轧制中几种常见的工作辊剥落类型,联系实际分析其产生的原因,并提出了相关的预防措施.     

Skin irritancy testing of toiletries and cosmetics on novel human models

A brief review of new techniques of assessing skin irritancy is presented. Some of the difficulties of assessing minor degrees of irritancy are discussed. Nouvelles méthodes pour l'évaluation sur l'être humain du pouvoir irritant des produits cosmetiques at d'hygiene     

Image analysis of skin scaling using D-Squame samplers: comparison with clinical scoring and use for assessing moisturizer efficacy

The severity of scaling disorders can be evaluated objectively using the D-Squame technique coupled with image analysis. The parameters of scaling derived using this approach need to be clinically relevant and should have greater discrimination than visual grading. Improvements to an existing method that fulfil these requirements are presented. Three scaling parameters were calculated using image analysis of digitized video-captured images of obliquely lit D-Squame samples. These parameters were compared to clinical scores of scaling made by five observers from photographs of the same areas sampled with D-Squame. In addition, two clinical studies were carried out to assess moisturizer effects on different degrees of xerosis, and to compare two different moisturizer preparations. The three scaling parameters gave correlation coefficients, r, between 0.6 and 0.75 when compared with global clinical scores of scaling. Significant reductions in all parameters were observed with 2 weeks of moisturizer use on lower leg skin with marked xerosis compared to an untreated control. The same moisturizer had a similar effect on milder xerosis of the forearm, and showed a greater decrease than a moisturizer with lower glycerol content. Increases in skin hydration, as measured with a corneometer, were also seen in both clinical studies, and corresponded well with D-Squame results. Differences in the degrees of scaling between these two anatomical sites were also detected with this technique. In a previous publication, the same technique was shown to be repeatable and reproducible; in the current article its correlation with clinical observations of scaling or flaking skin has been demonstrated.     

鲜姜高效化学脱皮工艺

对鲜姜的外皮进行选择性腐蚀 ,实现化学方法脱皮 ,研制出实用于山区农村的脱皮剂和其它制剂。研究出鲜姜化学脱皮的工艺 ,能够实现较大批量的流水生产 ,以便产地可以进行集中高效的生产。新工艺能提高姜制品的质量 ,不带入有毒物质 ,并能与姜块、姜片的烘干工艺衔接。     

超超临界机组锅炉蒸汽侧氧化层形成机理分析及预防措施

分析超超临界锅炉蒸汽侧管道氧化层的形成和剥落机理及影响氧化层生成的因素,从设备制造安装、调试、运行调整、质量监督、金属表面处理、氧化层厚度监测等6个方面提出抑制氧化层形成的对策。     

锥形齿轮轮齿开裂失效分析

锥形齿轮轮齿表面在检修时发现表层剥落。应用化学分析、金相检验、扫描电镜和硬度测试等断口分析方法对剥落的轮齿进行了分析。结果表明:齿轮的热处理组织形态基本正常,但组织粗大。齿轮开裂剥落的主要原因是轮齿中存在裂纹,在交变应力作用下扩展,直至表层剥落。     

Fe-Cr-C耐磨堆焊合金磨粒磨损行为

采用埋弧堆焊方法,在Q235钢表面制备Fe-Cr-C耐磨合金,在MLS—225型湿式橡胶轮磨粒磨损试验机上进行磨粒磨损试验,通过对磨损试样表面的扫描电子显微镜观察分析并结合能谱成分分析研究磨损形成机制.结果表明,Fe-Cr-C耐磨堆焊合金在试验的湿石英砂磨料磨损条件下,磨损机制以微裂纹引起的剥落去除机制为主,也存在一定数量的犁沟或犁皱造成的微切削去除机制.剥落的发生与碳化物密切相关,能谱成分分析表明剥落坑内Cr元素含量对应在(Cr,Fe)7C3铬含量范围内,说明剥落坑是碳化物断裂造成的.     

The Fate of Epidermal Tight Junctions in the stratum corneum: Their Involvement in the Regulation of Desquamation and Phenotypic Expression of Certain Skin Conditions

We evaluated the presence of tight junction (TJ) remnants in the stratum corneum (SC) of in vitro reconstructed human epidermis and human skin explants subjected or not to an aggressive topical treatment with beta-lipohydroxy salicylic acid (LSA) for 24 h. LSA-treated samples showed an increased presence of TJ remnants in the two lowermost layers of the SC, as quantified with standard electron microscopy. The topical aggression-induced overexpression of TJ-like cell–cell envelope fusions may influence SC functions: (1) directly, through an enhanced cohesion, and (2) indirectly, by impeding accessibility of peripheral corneodesmosomes to extracellular hydrolytic enzymes and, thus, slowing down desquamation. Observations of ichthyotic epidermis in peeling skin disease (PSD; corneodesmosin deficiency; two cases) and ichthyosis hypotrichosis sclerosing cholangitis syndrome (IHSC/NISCH; absence of claudin-1; two cases) also demonstrated increased persistence of TJ-like intercellular fusions in pathological SC and contributed to the interpretation of the diseases’ pathological mechanisms.