Skin barrier structure, function and formation - learning from cryo-electron microscopy of vitreous, fully hydrated native human epidermis

The hydration level of the stratum corneum largely depends on the physical state and molecular organization of the stratum corneum intercellular lipid matrix. A better understanding of stratum corneum lipid organization may thus aid the development of more rational cosmetic formulations. Several experimental and theoretical problems of a fundamental character remain, however, unresolved. These are, e.g. that precise quantitative skin barrier compositional data are difficult to obtain and that in vitro experimental skin barrier models usually are of limited value because of the prevailing non-equilibrium conditions in vivo. However, new experimental methods have recently been developed, which may help to overcome some of these limitations. These are, e.g. direct electrospray ionization-mass spectrometry (ESI-MS) of intact long-chain skin ceramides and direct high-resolution cryo-transmission electron microscopy (cryo-TEM) of vitreous sections of native, fully hydrated epidermis. Here, we show that cryo-transmission electron micrographs of vitreous normal human skin often dramatically differ from those obtained by conventional electron microscopy of resin-embedded skin. Our epidermal cryo-TEM data are subsequently discussed in relation to central problems of present conceptions of skin barrier structure, function and formation.     

Changes in lipid composition,fatty acid profile and lipid oxidative stability during Cantonese sausage processing

Lipid composition, fatty acid profile and lipid oxidative stability were evaluated during Cantonese sausage processing. Free fatty acids increased with concomitant decrease of phospholipids. Total content of free fatty acids at 72 h in muscle and adipose tissue was 7.341 mg/g and 3.067 mg/g, respectively. Total amount of saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA, and PUFA) in neutral lipid exhibited a little change during processing, while the proportion of PUFA significantly decreased in the PL fraction. The main triacylglycerols were POO + SLO + OOO, PSO (P = palmitic acid, O = oleic acid, L = linoleic acid, S = stearic acid), and a preferential hydrolysis of palmitic, oleic and linoleic acid was observed. Phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were the main components of phospholipids and PE exhibited the most significant degradation during processing. Thiobarbituric acid values (TBARS) increased while peroxide values and hexanal contents varied during processing.     

Particle size distribution and lipid composition of skim milk lipid material

Skim milk lipid material was characterized in terms of particle size distribution and lipid composition, and compared with other milk fat particle distributions. Whole milk, skim milk, large fat globules, small fat particles and skim milk lipid material were prepared using centrifugation and/or filtration, and the particle size distributions measured by laser diffraction. The lipid composition was determined using a combination of thin layer chromatography and gas chromatography–mass spectrometry. There were significant compositional differences between each fraction for both particle size distribution and fatty acid composition. The most distinguishing feature of the skim milk lipid material was the increased percentage of long chain sphingomyelin species compared with the other milk fat fractions.     

Organization,barrier function and antimicrobial lipids of the oral mucosa

As one moves from the skin across the vermilion region of the lip and into the oral cavity, the oral mucosa is encountered. The oral mucosa consists of connective tissue known as the lamina propria covered by a stratified squamous epithelium. In the regions of the hard palate and gingiva, the epithelium is keratinized like the epidermis. In the buccal region, the floor of the mouth and the underside of the tongue, the epithelium is non‐keratinized. The epithelium on the dorsum of the tongue is a specialized epithelium, but can be approximated as a mosaic of keratinized and non‐keratinized epithelia. The non‐keratinized epithelial regions do not produce a stratum corneum. Nuclei with intact DNA are retained in the superficial cells. In all regions, the outer portions of the epithelium provide a protective permeability barrier, which varies regionally. Antimicrobial lipids at the surfaces of the oral mucosa are an integral part of innate immunity.     

Intestinal absorption of fatty acids, and blood lipid composition in sheep

Interrelationships between intestinal uptake of fatty acids and their concentrations in lipids of blood plasma of sheep were assessed by quantities of individual fatty acids that flowed through and were absorbed from the intestinal tract under different dietary conditions. Major long-chain fatty acids were approximately 90% digested, thus demonstrating that dietary fatty acids of high melting points can be absorbed efficiently by ruminants provided they are well dispersed. Relationships were linear between uptakes of 16:0, 18:0, 18:1, and 18:2 fatty acids from the gut and their concentrations in both triglycerides and triglyceride-free plasma lipids. The proportion of each transferred to triglyceride-free plasma lipids was in order 18: 2 greater than 18:1 greater than 16:0 greater than 18:0, whereas in plasma triglycerides the order was 16:0 = 18:0 = 18:2 less than 18:1. Interconversion of 18:0 to 18:1 by intestinal mucosa may explain the anomalous behavior of 18:1 triglycerides. These results are consistent with the hypothesis that the intrinsic nature of the fatty acid primarily determines the composition of triglyceride-free plasma lipids whereas the relative amount of each acid absorbed by the intestine determines that of plasma triglycerides and, hence, of milk and depot fats of ruminants.     

Effect of fermentation,processing and storage on lipid composition of sauerkraut

The changes in lipid composition and fatty acid distribution of sauerkraut during fermentation, canning, processing and storage were investigated organoleptically and chemically. Treatments were significant throughout the experiment. pH, lactic acid, and moisture content did not reveal any substantial changes. Total lipids, neutral lipids, and glycolipids increased, whereas phospholipids were unaltered during fermentation and processing. Quantitative changes in nonpolar and polar lipids during storage were in opposite directions, and net lipid content did not change. The changes in fatty acid composition were primarily in the distribution of palmitic, stearic, oleic, linoleic and linolenic acids during fermentation, processing and storage. Total lipids did not relate to organoleptic evaluation. However, polar lipids, specifically phospholipids, were directly related to storage stability and increased amounts of general acceptability. The formation of phospholipids may be catalysed by a reaction between tin from the cans and polar lipids at the expense of neutral lipids.     

Protein and lipid composition of bovine milk-fat-globule membrane

Using mass spectrometry and other analytical methods, the proteins and lipids isolated from bovine milk-fat-globule membrane (MFGM) were characterised. The major MFGM protein composition consisted of xanthine oxidase, butyrophilin, adipophilin and periodic acid schiff 6/7. The minor proteins were polymeric immunoglobulin receptor protein, apolipoprotein E, apolipoprotein A1, 71 kDa heat-shock cognate protein, clusterin, lactoperoxidase, immunoglobulin heavy chain and peptidylprolyl isomerase A, actin, fatty acid-binding protein, cluster of differentiation 26 and mucin. The MFGM lipid component consisted predominantly of triglycerides (56%) and phospholipids (40.6%). The major fatty acids associated with the glycerol phospholipids were C16:0, C18:0, C18:1 and C18:2. Sphingomyelin had a high proportion of C20:0, C23:0, C24:1 and C24:0 fatty acids linked to the sphingoloid base. However, the sphingoloid base itself consisted predominantly of C16:1, C17:1 and C18:1 fatty acids. Small amounts of both lactosyl- and glucosyl-cerebrosides were found in the bovine MFGM sample and trace levels of lyso-phosphatidyl ethanolamine and lyso-phosphatidyl choline were detected.     

蛋黄油脂质组分的提取分离与脂肪酸组成分析

为将蛋黄油分为不同性质的脂质组分,并建立一种从蛋黄粉中提取分离蛋黄油的方法,利用溶剂萃取法从蛋黄粉中提取蛋黄油,以出油率、碘值和皂化值为指标筛选蛋黄油提取萃取剂、去磷脂蛋黄油提取萃取剂以及去磷脂蛋黄油分离萃取剂;对除磷脂外的3种蛋黄油组分进行脂肪酸组成分析。结果表明：以无水乙醇作为一次提取萃取剂从蛋黄粉中得到醇提蛋黄油与醇提蛋黄粉,用石油醚对醇提蛋黄粉进行二次提取得到石油醚蛋黄油,采用丙酮以料液比1∶12分离醇提蛋黄油中磷脂并得到去磷脂醇提蛋黄油,以乙腈-乙醇(体积比1∶1)分离去磷脂醇提蛋黄油得到上层蛋黄油与下层蛋黄油;蛋黄粉中的脂质被分为4个组分,其中上层蛋黄油占18.43%,下层蛋黄油占40.62%,石油醚蛋黄油占9.78%,磷脂占31.16%;3种液态蛋黄油中,上层蛋黄油不饱和度最高,多不饱和脂肪酸占比最大(20.52%),还含有较多ω-3多不饱和脂肪酸等具有保健功效的脂肪酸。该方法可分离出蛋黄油中高多不饱和脂肪酸和较高保健功效脂肪酸占比的液态脂质。     

The lipid composition of the adrenals of non-pregnant,pregnant and foetal sheep

Lipids were isolated from the adrenals of non-pregnant, pregnant and foetal sheep (ca 30 days pre-parturition). The lipid content of the adrenals from the pregnant sheep was higher than that of the other groups, and most of this was accounted for by triacylglycerols. Little difference was observed in the fatty acid compositions of the various lipid classes between the pregnant and non-pregnant animals. All the lipids of the foetal adrenals contained substantial amounts of the 20:3(n–9) fatty acid, which is often associated with essential fatty acid deficiency, but only the cholesterol ester fraction contained a higher level of polyunsaturated fatty acids than was present in the adult groups. The adrenals of the pregnant sheep contained significant levels of glycerolether diesters and neutral plasmalogens, which were fully characterised, and four unknown components that were tentatively identified as steroidal esters. These components were present at barely detectable levels in the adrenals of non-pregnant sheep. The triacylglycerols, glycerolether diesters and phosphatidylcholines from each group were, where possible, subjected to stereospecific analysis. The triacylglycerols were distinctive and resembled those of plasma and lymph in structure. The results are discussed in terms of a putative direct role for cholesterol esters in corticosteroidogenesis.     

Physical activity-induced alterations on tissue lipid composition and lipid metabolism in fattening pigs

In a first experiment one group of pigs was maintained in free-range conditions according to the traditional way in a Mediterranean forest (exercised-1) and another group was housed individually and received acorns (sedentary-1). In a second experiment two groups of pigs were fed a mixed diet for the whole experimental period. One of these groups was housed individually in 8 m² pens (sedentary-2). The other group was housed in a corridor and forced to walk daily (exercised-2).The subcutaneous fat and neutral lipids of muscle from the exercised pigs fed acorns had higher C18:1n-9, MUFA, C18:1/C18:0, MUFA/SAT and lower C16:0 and SAT when compared with the fat from the pigs fed acorns in confinement. Those exercised animals fed the mixed diet had also lower C16:0 and SAT in subcutaneous fat and lower SAT and higher C18:2, C18:3, PUFA and MUFA/SAT in neutral lipids when compared with the sedentary pigs, which may indicate that delta-9-desaturase activity was higher in exercised than in sedentary pigs. Exercised pigs had higher acid and neutral esterases and lower neutral lipase activity than sedentary pigs. No differences in the α-tocopherol concentration and TBARS values of meat samples among the pigs that received a mixed diet either exercised or sedentary were observed. The moderate exercise reduced the postprandrial concentrations of triglycerides in plasma, but did not reduce other plasma levels.     

Total lipid,fatty acid composition and lipid oxidation of Indian white shrimp (Fenneropenaeus indicus) fed diets containing different lipid sources

BACKGROUND: Seafood is an important constituent of the human diet. In Iran, Indian white shrimp (Fenneropenaeus indicus) is the major cultured shrimp species as a result of market demand, local availability and growth rate. It is mainly reared using commercial feed. The purpose of this study was to evaluate the effects of replacing 50% of the fish oil by vegetable oils in shrimp feed on total lipid, fatty acid composition and lipid oxidation of shrimp muscle. RESULTS: No significant differences in total lipid content (6.1–7.3 g kg^?1) were found between edible tissues of shrimp fed different diets. The major fatty acids in shrimp muscle were palmitic, oleic, lionoleic, stearic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Higher levels of EPA and DHA were observed in muscle of shrimp fed a diet containing fish oil. Oxidative rancidity, measured as thiobarbituric acid reactive substances, for all shrimps did not exceed 0.2 mg malonaldehyde kg^?1 muscle tissue, which was low and acceptable. CONCLUSION: This study had shown that the fatty acid composition of feed directly affects the fatty acid composition of Indian white shrimp muscle. Farmed Indian white shrimp can be considered as a species of low fat and shrimp muscle was quite stable to oxidation during storage. Copyright © 2009 Society of Chemical Industry     

Effect of a linseed diet on lipid composition, lipid peroxidation and consumer evaluation of French fresh and cooked pork meats

Twenty castrated pigs [(Large-White × Landrace) × (Pietrain)] (52.9 ± 5.1 kg initial body weight) were fed a control or a linseed diet containing 4.2% of extruded linseed. Animals were slaughtered at 106.6 ± 3.7 kg live weight. There was no effect of diet on pig performance. Feeding the linseed diet increased the contents of n−3 polyunsaturated fatty acids (PUFA) in chops (raw and cooked), chitterlings sausages, country style pâté, garlic sausages, liver pâté, and smoked belly. However, docosahexaenoic acid (DHA) level was not affected by the linseed diet. The linseed diet produced a robust decrease in the n−6/n−3 and linoleic acid (LA)/α-linolenic acid (ALA) ratios (<4). Feeding pigs with a high n−3 PUFA diet led to a decrease in the oxidative stability of chops, in contrast to smoked bellies for which thiobarbituric acid-reactive substances (TBARS) values were not affected by the diet. However, there was no deleterious effect on consumer overall appreciation of the meat.     

10种热带富油微藻生物量、总脂含量 及脂肪酸组成分析

微藻生物柴油是当前生物能源中最具发展潜力的一种新型能源,为更好地开发微藻生物柴油,筛选出适合制备生物柴油的富油微藻,以10种热带富油微藻为研究对象,对其生物量、总脂含量及脂肪酸组成进行分析。通过甲醇-氯仿(体积比为2∶1)称量法测定10种热带富油微藻中的总脂含量,将从微藻提取的油脂经过甲酯化反应后,采用气相色谱-质谱联用(GC-MS)分析油脂中脂肪酸组成及含量。结果表明,10种热带富油微藻中Chlorella vulgaris CJ15和Desmodesmus sp.WC08更适合制备生物柴油。     

The chemistry,function and (patho)physiology of stratum corneum barrier ceramides

Research on understanding of the chemistry, function and (patho)physiology of stratum corneum (SC) lipids and especially ceramides has evolved over the last two decades. This has been made successful through the application of separation techniques that have become increasingly more sophisticated, and it has become increasingly evident that our understanding of these molecules remains in its infancy. Thirteen classes of ceramides with over 300 and possibly up to 1000 distinct ceramide species have been identified suggesting an exquisitely subtle relationship between the types of ceramides and physical and chemical behaviour. Nevertheless, research has demonstrated the importance of the correct SC lipid lamellar architecture with conformationally‐ordered lipid bilayers, the presence of long‐chain ceramides, as either free or covalently bound lipids, greater quantities of phytosphingosine‐containing ceramides and a high SC lipid/protein ratio is essential for optimal barrier function. These features are known to change in a variety of physiological and pathophysiological conditions. Clearly, there is more to be learned but as we further decipher the complexity of SC lipids and understand their individual roles in the SC, we will learn how to better treat the disorders of cornification.     

Caffeine improves barrier function in male skin

The influence of androgens, especially testosterone and its effector dihydrotestosterone, results in a constitutive disadvantage for male skin, e.g. reduced viability of hair at the scalp and reduced epidermal permeability barrier repair capacity. Dihydrotestosterone can act, among others, as an adenyl cyclase inhibitor. Caffeine on the other hand is an inexpensive and (in regular doses) harmless substance used in various cosmetic products, which can act as a phosphodiesterase inhibitor. To prove the hypothesis that caffeine as a phosphodiesterase inhibitor is able to override testosterone-induced effects on barrier function, we performed a double-blind placebo controlled study with healthy volunteers. In this study, 0.5% caffeine in a hydroxyethylcellulose gel preparation (HEC) was applied on one forearm, HEC without caffeine on the other forearm of male and female volunteers for 7 days and transepidermal water loss (TEWL) was measured before and at the end of the treatment period. Basal TEWL did not differ significantly between male and female subjects but the application of caffeine significantly reduced TEWL in male skin compared with female skin. We conclude that caffeine is beneficial for barrier function in male skin.     

Effect of excess dietary iron on lipid composition of calf liver, heart, and skeletal muscle

Effect of excess dietary iron on lipid composition of calf liver, skeletal muscle, and heart was assessed. High dietary iron (5000 versus 100 ppm in milk replacer DM) had no effect on the relative proportion of lipid classes in liver or their unsaturated fatty acid composition. In muscle some minor lipid components were reduced and cholesterol and sphingomyelin increased. Excessive iron had a marked effect, however, on heart lipid composition, reducing total lipids and almost all lipid classes; triglycerides, sphingomyelin, and lysophosphatidylcholine were increased. Characteristically, sphingomyelin increases in cell membranes in response to aging and numerous pathological conditions. High dietary iron reduced linolenic acid in phosphatidyl-ethanolamine and phosphatidylcholine of both skeletal and cardiac muscle. This may have resulted from iron-caused ethane production from autoxidation of linolenic acid or other n-3 family fatty acids, an effect known to occur in the rat. Linoleic and arachidonic fatty acids appeared to be unaffected. Plasmalogens in muscle and heart phosphatidylethanolamine and phosphatidylcholine were increased by high iron intake. As these alk-1-enyl ethers protect cells from oxidation and radiation damage, their synthesis may have been increased in response to stress from excessive iron. The results indicate that a relatively high concentration of vitamin E may be required in calf milk replacer when excessive iron is present.     

Fatty acid composition, antioxidants and lipid oxidation in chicken breasts from different production regimes

Chicken breast from nine products and from the following production regimes: conventional (chilled and frozen), organic and free range, were analysed for fatty acid composition of total lipids, preventative and chain breaking antioxidant contents and lipid oxidation during 5 days of sub‐ambient storage following purchase. Total lipids were extracted with an optimal amount of a cold chloroform methanol solvent. Lipid compositions varied, but there were differences between conventional and organic products in their contents of total polyunsaturated fatty acids and n‐3 and n‐6 fatty acids and n‐6:n‐3 ratio. Of the antioxidants, α‐tocopherol content was inversely correlated with lipid oxidation. The antioxidant enzyme activities of catalase, glutathione peroxidase and glutathione reductase varied between products. Modelling with partial least squares regression showed no overall relationship between total antioxidants and lipid data, but certain individual antioxidants showed a relationship with specific lipid fractions.     

Influence of lipid composition, crystallization behavior and microstructure on hardness of palm oil-based margarines

Two typical commercial palm oil-based margarines, denoted A (complained as with over-hardness) and B (commercially considered as with acceptable hardness), respectively, were compared in terms of hardness, solid fat content (SFC), lipid composition [fatty acid and triacylglycerol (TAG) composition], crystallization behavior and microstructure. On the basis of these results, the reason of over-hardness in margarine A was discussed. Margarine A showed higher hardness than margarine B with the differences increasing along with rise in temperature in the typical range from 15 to 30 °C. While margarine B has good quality and appropriate hardness, it showed SFCs higher than margarine A. Lipid composition analyses showed that margarine B has small amounts of medium chain fatty acids and higher content of monounsaturated TAGs [1,3-dipalmitoyl-2-oleoyl-glycerol (POP), 1,3-dipalmitoyl-2-linoleoyl-glycerol (PLP), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS)]. X-ray diffraction analysis revealed that both margarines have β′ and β polymorphs with the β form being dominant in margarine B. Isothermal crystallization kinetics of both margarines under 15, 20, 25, and 30 °C, respectively, fitted using the Avrami model indicates that margarine B hardly crystallizes at temperatures ≥25 °C. Morphologic observations of the microstructure of both margarines by polarized light microscope and scanning electron microscopy showed that formation of large spherulites have an important influence on margarine texture. Occurrence of large spherulites in margarine B is considered to decrease the numbers of crystals and lessen mutual attraction with temperature increasing, which leads to weakened strength of the total network, even if margarine B has a higher SFC value.     

子营养成分及功能利用研究进展

穇子是一种非常重要的作物,含有丰富的营养物质及较高的膳食纤维、多酚、矿物质和含硫氨基酸。穇子有抗氧化与抗衰老、抗癌、预防糖尿病、保护心脏和抗高血脂等生理功能。在国外,穇子除了被加工成穇子粉、穇子饼、穇子球等传统食品外,还被制成穇子麦芽和发酵食品等。然而,我国对穇子的研究非常少,关于穇子的产品也不多,严重制约我国穇子产业的发展。本文将从穇子的营养成分、生理功能及加工利用这三个方面进行综述,以期待给我国穇子的加工者和研究者提供一定的借鉴。