Glycosphingolipids of human thyroid

Glycosphingolipids were isolated from total lipids of female and male human thyroids by alkaline hydrolysis, silicic acid, diethylaminoethyl-celluose and thin layer chromatography and analyzed by gas liquid chromatography. On the basis of their mobility in two dimensions on thin layer chromatography, IR analysis, and of sugar molar ratio, four neutral glycolipids, a sulfatide, and a hematoside fraction were identified. Glucosyl, plus galactosyl ceramide, and trihexosyl ceramide were the major fractions and accounted for 33% and 28% of total neutral glycolipids, respectively. Dihexosyl ceramide was a mixture of lactosyl and digalactosyl ceramide. The acidic lower phase glycolipids comprised ceramide galactosyl sulfate as the major component of male thyroids. Hematoside was identified tentatively as a minor component of the thyroids of both sexes. Major fatty acids of all neutral glycolipid fractions were 20∶0, 22∶0, 24∶0, and 24∶1; 24∶0 and 24∶1 for sulfatides. Low proportions of α-hydroxy fatty acids were identified. Total neutral glycosphingolipids of male thyroids were comparable in quantities with human liver but lower than kidneys, leucocytes, and platelets. Male thyroids comprised higher quantities of neutral glycosphingolipids (4.04±0.32 μmoles/g total lipid) as compared to females (2.34±0.21 μmoles/g total lipid), and much higher sulfatide than the females. These marked differences may suggest that the biosynthesis of the glycosphingolipids in the thyroid gland is under hormonal control. Similarities in glycosphingolipid composition of human thyroid and kidney are discussed in relation to a possible role played by glycolipids in ion transport, which is a common feature of the two organs.     

Glycosphingolipids of human plasma lipoproteins

The content and structure of glycosphingolipids (GSL) in human plasma lipoproteins were studies. The quantitative distribution of the neutral GSL(Glc-Cer, Gal-Glc-Cer, Gal-Gal-Glc-Cer, and GalNAc-Gal-Gal-Glc-Cer) and the principal ganglioside (AcNeu-Gal-Glc-Cer) within the different lipoprotein classes was similar to that of whole plasma. The total amounts (μmol glucose/100 ml plasma) of GSL in the plasma lipoproteins of three normal subjects were VLDL (very low density lipoproteins) (trace to 0.46), LDL (low density lipoproteins) (1.08–1.48), HDL₂ (high density lipoproteins₂) (0.62–0.85), and HDL₃ (high density lipoproteins₃) (trace to 0.28). In subjects with Lp(a) lipoproteins, HDL₂ rather than HDL₃ contained most of the GSL in HDL. When the data were corrected for differences in the plasma concentrations of the lipoproteins, the total amounts of GSL(nmol glucose/mg lipoprotein cholesterol) were VLDL(trace to 21.20), LDL(11.70–15.36), HDL₂(8.50–9.10), and HDL₃(3.12). No GSL were detected in lipoprotein deficient plasma. Mass spectrometry of the trimethylsilyl derivatives of the GSL in LDL showed major fragment ions characteristic of their individual structural components. The elevated plasma levels of the GSL(2–18 fold), in a homozygote for familial hypercholesterolemia, resided in LDL which contained an absolute increase (per mg lipoprotein cholesterol) of GSL. Most, if not all, of the plasma GSL are associated with plasma lipoproteins and may have an important role in their biological functions.     

n-3 fatty acids decrease colonic epithelial cell proliferation in high-risk bowel mucosa

The n-3 fatty acids (C20∶5, eicosapentaenoic acid; C22∶6, docosahexaenoic, acid) may be important in the development, growth, and metastasis of colon cancer, a leading cause of death in North America. Patients who have had a bowel neoplasm have a high risk of developing a second neoplasm, and this risk is associated with a high percentage of cells correspond to the S phase of bromodeoxyuridine (BrdUrd) labeling in mucosal epithelial cells. To determine the effect of n-3 fatty acid supplementation on DNA synthesis of rectal mucosa, patients with stage 1 or stage 2 colon carcinoma or adenomatous polyps were randomized to consume either 9 g/d n-3 fatty acid capsules or 9 g/d placebo capsules. Plasma phospholipid fatty acid analysis and proctoscopic mucosal biopsies were performed at baseline, 3, and 6 mon. Colonic crypts were isolated from the mucosa, disassociated with enzymes, and incubated with BrdUrd, and %S phase was measured by flow cytometry. The plasma phospholipid n-6/n-3 ratio was determined by gas chromatography. Supplement compliance was assessed by plasma phospholipid n-6/n-3 ratio. Mean capsule consumption in these two group was 82%. Prior to supplementation, there were no significant differences in the %S phase and the plasma n-6/n-3 ratio between these groups. Patients whose colonic epithelial cells indicated hyperproliferation at baseline showed a strongly positive correlation to the %S phase of BrdUrd uptake and the n-6/n-3 ratio. There was no significant change after n-3 treatment in patients with low baseline. Those in the placebo group showed no significant difference in n-6/n-3 ratio, although there was an increase in the %S phase of BrdUrd uptake at 6 mon. The n-3 group did not have significant side effects, and polyps were not found after completing 12 mon of n-3 fatty acid supplementation. This study suggests that n-3 fatty acid may be a useful chemopreventive agent in some patients as reflected in a plasma biomarker of colon tumor growth and metastasis. A low plasma phospholipid n-6/n-3 fatty acid ratio may serve as a nutritional marker that is associated with colonic epithelial cell hyperproliferation in the n-3-supplemented group as compared with the placebo group. Characteristics of mucosal proliferation at baseline may be a crucial factor for the effect of n-3 fatty acid supplementation.     

Glycosphingolipids of white cells lymphoid tissue and bone marrow

Glycosphingolipids of lymphoid tissues, bone marrow cells, mixed blood leucocytes, separated lymphocytes, and granulocytes from large white pigs were analyzed by thin layer and gas liquid chromatographies. The composition of the glycosphingolipids of thymus and blood leucocytes (mixed population) was similar, and trihexosyl ceramide (galactosyl-[1–4]-galactosyl-[1–4]-glucosyl-[1–1]-ceramide) was the major glycosphingolipid component of both tissues. The fatty acid fractions of all glycolipids from the two tissues were analyzed, and gross differences are discussed. Blood lymphocytes had a higher content of glycosphingolipids/mole phospholipid or mg protein than thymus lymphocytes obtained by a gentle washing of sliced tissue. Similar and more pronounced differences were obtained when the glycosphingolipid content of bone marrow cells (>50% polymorphonuclear neutrophils) was compared with that of blood polymorphonuclear neutrophils. In general, most of the blood leucocytes were richer in glycosphingolipids than most of the cells of the lymphoid tissues and bone marrow. These results indicate a marked difference in lipid composition between blood polymorphonuclear neutrophils and bone marrow cells. It is possible that certain of the biophysical properties which characterize blood polymorphonuclear neutrophils and which derive from changes in the cell periphery of immature granulocytes are connected with these differences in membrane lipid composition.     

Production of human normal adult and fetal hemoglobins in Escherichia coli

A hemoglobin expression system in Escherichia coli is described. In order to produce authentic human hemoglobin, we need to co-express both methionine aminopeptidase and globin genes under the control of a strong promoter. We have constructed three plasmids, pHE2, pHE4 and pHE7, for the expression of human normal adult hemoglobin and a plasmid, pHE9, for the expression of human fetal hemoglobin, in high yields. The globin genes can be derived from either synthetic genes or human globin cDNAs. The extra amino-terminal methionine residues of the expressed globins can be removed by the co-expressed methionine aminopeptidase. The heme is inserted correctly into the expressed alpha- globin from our expression plasmids. A fraction (approximately 25%) of the heme is not inserted correctly into the expressed beta- or gamma- globin. However, the incorrectly inserted hemes can be converted into the correct conformation by carrying out a simple oxidation-reduction process on the purified hemoglobin molecule. We have investigated the functional properties of the expressed hemoglobins by measuring their oxygen-binding properties and their structural features by obtaining their 1H-NMR spectra. Our results show that authentic human normal adult and fetal hemoglobins can be produced from our expression plasmids in E. coli and in high yields. Our expression system allows us to design and to produce any recombinant hemoglobins needed for our research on the structure-function relationship in hemoglobin.      

Characterization of Glycosphingolipids in the Human Parathyroid and Thyroid Glands

As part of a systematic investigation of the glycosphingolipids in human tissues, acid and non-acid glycosphingolipids from human thyroid and parathyroid glands were isolated and characterized with mass spectrometry and binding of carbohydrate-recognizing ligands, with a focus on complex compounds. The glycosphingolipid patterns of the human parathyroid and thyroid glands were very similar. The major acid glycosphingolipids were sulfatide and the gangliosides GM3, GD3, GD1a, GD1b, GT1b and Neu5Ac-neolactotetraosylceramide, and the major non-acid glycosphingolipids were globotriaosylceramide and globoside. We also found neolactotetra- and neolactohexaosylceramide, the x₂ glycosphingolipid, and complex glycosphingolipids with terminal blood group O and A determinants in both tissues. A glycosphingolipid with blood group Le^b determinant was identified in the thyroid gland, and the parathyroid sample had a glycosphingolipid with terminal blood group B determinant. Immunohistochemistry demonstrated the expression of blood group A antigens in both the thyroid and parathyroid glands. A weak cytoplasmatic expression of the GD1a ganglioside was present in the thyroid, while the parathyroid gland had a strong GD1a expression on the cell surface. Thus, the glycosylation of human thyroid and parathyroid glands is more complex than previously appreciated. Our findings provide a platform for further studies of alterations of cell surface glycosphingolipids in thyroid and parathyroid cancers.     

Cancer-Associated Glycosphingolipids as Tumor Markers and Targets for Cancer Immunotherapy

Aberrant expression of glycosphingolipids is a hallmark of cancer cells and is associated with their malignant properties. Disialylated gangliosides GD2 and GD3 are considered as markers of neuroectoderm origin in tumors, whereas fucosyl-GM1 is expressed in very few normal tissues but overexpressed in a variety of cancers, especially in small cell lung carcinoma. These gangliosides are absent in most normal adult tissues, making them targets of interest in immuno-oncology. Passive and active immunotherapy strategies have been developed, and have shown promising results in clinical trials. In this review, we summarized the current knowledge on GD2, GD3, and fucosyl-GM1 expression in health and cancer, their biosynthesis pathways in the Golgi apparatus, and their biological roles. We described how their overexpression can affect intracellular signaling pathways, increasing the malignant phenotypes of cancer cells, including their metastatic potential and invasiveness. Finally, the different strategies used to target these tumor-associated gangliosides for immunotherapy were discussed, including the use and development of monoclonal antibodies, vaccines, immune system modulators, and immune effector-cell therapy, with a special focus on adoptive cellular therapy with T cells engineered to express chimeric antigen receptors.     

Lipoproteins of fetal and newborn calves and adult steer: A study of developmental changes

Serum lipoproteins in fetal and newborn calves were characterized and compared with those of adult animals. Fetal calf serum contains only low density (LDL) and high density (HDL) lipoproteins; the LDL is the major lipoprotein class. Fetal LDL are ca. 26.0 nm diameter and are morphologically unusual in that particles form linear aggregates or “chains” in which LDL have flattened, parallel sides. These particles contain only apolipoprotein B and are high in polar lipids. Fetal HDL consist of 8.2-nm, round particles which contain large amounts of chlesteryl ester thus suggesting an active lecithin: cholesterol acyltransferase system in the fetal state. The major protein in fetal HDL is apolipoprotein A−I (80%); however, another component with a molecular weight (MW) of ca. 9,000 is also present. Newborn calves show a 5-fold increase in HDL concentration. These particles are 9.0 nm spherical particles and they contain mainly apolipoprotein A−I although C-apolipoproteins are also present; the lipid and apolipoprotein composition of newborn HDL is similar to that of adults. Newborn calves possess very low density (VLDL) lipoproteins which have a mean diameter of 61 nm and are similar in size and composition to those of adult animals; their apolipoprotein composition is principally apolipoprotein B, although C-apolipoproteins and apolipoprotein A−I are also present. The LDL of neonatal and adult animals are similar in morphology, chemical composition and apolipoprotein content. In both instances, LDL are round particles ca. 19.0 nm diameter which contain less polar lipids than the fetal animal. Apolipoprotein B is the major protein in newborn LDL, but adult LDL additionally contains a protein of 27,000 MW which probably represents apolipoprotein A−I from overlapping α-migrating particles in this region. The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo. Preliminary data was presented at the American Oil Chemists' Society Meeting, 1979.     

Application of the Antibody-Inducing Activity of Glycosphingolipids to Human Diseases

Glycosphingolipids (GSLs) are composed of a mono-, di-, or oligosaccharide and a ceramide and function as constituents of cell membranes. Various molecular species of GSLs have been identified in mammalian cells due to differences in the structures of oligosaccharides. The oligosaccharide structure can vary depending on cell lineage, differentiation stage, and pathology; this property can be used as a cell identification marker. Furthermore, GSLs are involved in various aspects of the immune response, such as cytokine production, immune signaling, migration of immune cells, and antibody production. GSLs containing certain structures exhibit strong immunogenicity in immunized animals and promote the production of anti-GSL antibodies. By exploiting this property, it is possible to generate antibodies that recognize the fine oligosaccharide structure of specific GSLs or glycoproteins. In our study using artificially synthesized GSLs (artGSLs), we found that several structural features are correlated with the antibody-inducing activity of GSLs. Based on these findings, we designed artGSLs that efficiently induce the production of antibodies accompanied by class switching and developed several antibodies that recognize not only certain glycan structures of GSLs but also those of glycoproteins. This review comprehensively introduces the immune activities of GSLs and their application as pharmaceuticals.     

Total glycerophospholipid fatty acid and phospholipid class composition of nerve ending and related fractions from fetal and adult pig cerebellum and adult pig whole brain cortex

Membrane fractions derived from crude mitochondrial fractions of pig cerebellums were separated on a continuous CsCl-sucrose gradient. Fetal and adult brains were used as starting material. The major differences in total glycerophospholipid fatty acid composition between fetal and adult membranes were an increase with maturation in docosahexaenoic acid and a decrease in palmitic acid which occurred in all membranes, including nerve ending and smooth membrane fractions. Phosphatidylcholine levels decreased, and ethanolamine phosphatide levels increased with maturation in all adult membrane fractions. Phosphatidylserine levels increased primarily in nonmitochondrial fractions in adult tissues. The results indicate that both hydrophobic and hydrophylic characteristics of several membrane fractions, including nerve endings, change with development. The developmental changes in pig cerebellums are similar to those reported for whole brain or brain regions from other species. Mitochondrial enriched fractions derived from adult pig whole brain cortex had significantly reduced palmitate levels and significantly elevated oleate levels compared with nerve ending and smooth membrane fractions.     

European Union's rapid TSE testing in adult cattle and sheep: implementation and results in 2001 and 2002

After the discovery of variant Creutzfeldt-Jakob disease (vCJD), scientific advances quickly led to post-mortem tests to identify late-stage bovine spongiform encephalopathy (BSE) disease. These were first used in Switzerland in 1999 for active BSE surveillance of a) fallen and emergency-slaughter bovines (risk stock) and b) 5% sample of routinely slaughtered cattle over 30 months of age. In 1999 and 2000, Switzerland's estimated 103 BSE positives per 1000000 adult cattle put it in the same BSE risk classification as UK and Portugal. In July 2000, the European Union's Scientific Steering Committee published its methodology (and first vetted results) for geographical BSE risk (GBR) assessment in cattle. Member states with no BSE cases found themselves, on rational assessment, classified as GBR III (BSE likely but not confirmed, or confirmed at a lower level). Because of Europe's thus highly assessed BSE risks, active BSE surveillance of adult cattle in all member states began in January 2001 using one of three validated post-mortem tests. Implementation was variable across member states in January to March 2001 but, where operational, active surveillance was typically achieved for around 13300 routinely slaughtered and 1000 risk stock per month per 1000000 adult cattle; BSE positive rates were 60 and 600 per 1000000 routinely slaughtered and risk cattle, respectively. By the second half of 2001, active BSE surveillance was operating reasonably in most member states, although anomalies persisted. Performance and results for July to December 2001 and for January to June 2002 are considered in detail. The BSE positive rate decreased substantially in UK, Portugal and Ireland between semesters, whereas Spain's rates increased for both routinely slaughtered and risk bovines. Based on 1450000 routinely slaughtered and 135000 risk stock as standard, France could have expected 153 BSE positives in July to December 2001 (109 in January to June 2002); Italy 154 (67); and Germany only 39 (48). When sample-based surveillance data were scaled up and combined with clinical BSE cases, Great Britain's BSE positives were estimated at around 400 per 1000000 adult cattle in 2002 compared with over 1000 per 1000000 adult cattle in 2000. Age distributions for cattle subject to active BSE surveillance have been underexploited. The major transmissible spongiform encephalopathy (TSE) which affects sheep and goats is scrapie. Passive surveillance of scrapie is associated with substantial under-reporting. Susceptibility to scrapie depends strongly on sheep genotype; but resistance to scrapie does not necessarily confer resistance of sheep to BSE. Because of uncertainty about the true prevalence of scrapie-infected adult sheep and concern that BSE in sheep may be missed, the European Union pre-empted its planned evaluation of rapid post-mortem TSE tests in sheep by requiring the rapid TSE testing of small ruminants from April 2002 with one of the three cattle-validated tests. Basic requirements for active TSE surveillance in sheep were: random sample of 6000 fallen sheep and of 60000 routinely slaughtered adult native sheep to be tested per member state by end March 2003. Lower surveillance targets were set for countries with under 1000000 adult sheep. Adequately to map scrapie-susceptible genotypes and identify resistant genotypes, a random sample of 500 routinely slaughtered native adult sheep was to be genotyped, together with each TSE rapid test positive adult sheep and two sets of three suitably sampled controls. By the end of August 2002, when 41% of the initial surveillance time had elapsed, only 20% of the European joint target for routinely slaughtered adult sheep had been completed, but that for fallen sheep was exceeded. Except in Ireland, the upper 95% confidence bound on TSE prevalence exceeded 500 per 1000000 routinely slaughtered adult sheep in reporting-compliant countries with more than 1000000 adult sheep. The UK, Greece, Italy and France were likely to approach the goal of 100 TSE rapid test positives on completion of their assigned first-year surveillance target for sheep. Results from the recommended genotyping of TSE positive adult sheep and controls for use in inferring differential TSE-positive susceptibility by genotype are awaited. Only by genotyping 5000-50000 TSE-positive adult sheep, a massive undertaking even on the European scale, will it become clear whether scrapie resistance is relative rather than absolute. This paper details Europe's quantitative evolution in TSE surveillance.     

Deleterious effects of high dose connexin 43 mimetic Peptide infusion after cerebral ischaemia in near-term fetal sheep

Hypoxic-ischaemic brain injury at birth is associated with 1-3/1000 cases of moderate to severe encephalopathy. Previously, we have shown that connexin 43 hemichannel blockade, with a specific mimetic peptide, reduced the occurrence of seizures, improved recovery of EEG power and sleep state cycling, and improved cell survival following global cerebral ischaemia. In the present study, we examined the dose response for intracerebroventricular mimetic peptide infusion (50 μmol/kg/h for 1 h, followed by 50 μmol/kg/24 h (low dose) or 50 μmol/kg/h for 25 h (high dose) or vehicle only (control group), starting 90 min after the end of ischaemia), following global cerebral ischaemia, induced by 30 min bilateral carotid artery occlusion, in near-term fetal sheep (128 ± 1 days gestation). Both peptide infusion groups were associated with a transient significant increase in EEG power between 2-12 h after ischaemia. The ischaemia-low dose group showed a significant recovery of EEG power from day five compared to the ischaemia-vehicle and -high dose groups. In contrast, the high dose infusion was associated with greater secondary increase in impedance (brain cell swelling), as well as a trend towards a greater increase in lactate concentration and mortality. These data suggest that higher doses of connexin mimetic peptide are not beneficial and may be associated with adverse outcomes, most likely attributable to uncoupling of connexin 43 gap junctions leading to dysfunction of the astrocytic syncytium.     

Glycosphingolipids in Diabetes,Oxidative Stress,and Cardiovascular Disease: Prevention in Experimental Animal Models

Diabetes contributes to about 30% morbidity and mortality world-wide and has tidal wave increases in several countries in Asia. Diabetes is a multi-factorial disease compounded by inflammation, dyslipidemia, atherosclerosis, and is sometimes accompanied with gains in body weight. Sphingolipid pathways that interplay in the enhancement of the pathology of this disease may be potential therapeutic targets. Thus, the application of advanced sphingolipidomics may help predict the progression of this disease and therapeutic outcomes in man. Pre-clinical studies using various experimental animal models of diabetes provide valuable information on the role of sphingolipid signaling networks in diabetes and the efficacy of drugs to determine the translatability of innovative discoveries to man. In this review, we discuss three major concepts regarding sphingolipids and diabetes. First, we discuss a possible involvement of a monosialodihexosylceramide (GM3) in insulin–insulin receptor interactions. Second, a potential role for ceramide (Cer) and lactosylceramide (LacCer) in apoptosis and mitochondrial dysfunction is proposed. Third, a larger role of LacCer in antioxidant status and inflammation is discussed. We also discuss how inhibitors of glycosphingolipid synthesis can ameliorate diabetes in experimental animal models.     

Gb3 Glycosphingolipids with Fluorescent Oligoene Fatty Acids: Synthesis and Phase Behavior in Model Membranes

Glycosphingolipids are involved in a number of physiological and pathophysiological processes, and they serve as receptors for a variety of bacterial toxins and viruses. To investigate their function in lipid membranes, fluorescently labeled glycosphingolipids are highly desirable. Herein, a synthetic route to access Gb₃ glycosphingolipids with fluorescently labeled fatty acids, consisting of pentaene and hexaene moieties either at the terminus or in the middle of the acyl chain, has been developed. The fluorescent properties of the Gb₃ derivatives were investigated in small unilamellar vesicles composed of a raft-like mixture. Phase-separated giant unilamellar vesicles (GUVs) allowed the quantification of the apparent partitioning coefficients of the Gb₃ compounds by means of confocal fluorescence laser scanning microscopy. The determined partition coefficients demonstrate that the Gb₃ derivatives are preferentially localized in the liquid-disordered (l_d) phase. To analyze whether the compounds behave like their physiological counterparts, Cy3-labeled (Cy: cyanine) Shiga toxin B subunits (STxB) were specifically bound to Gb₃-doped GUVs. However, the protein was favorably localized in the l_d phase, in contrast to results reported for STxB bound to naturally occurring Gb₃, which is discussed in terms of the packing density of the lipids in the liquid-ordered (l_o) phase.     

Structural Characterization of Neutral Glycosphingolipids from 3T3‐L1 Adipocytes

In recent years, obesity has been considered a pathological stage of early lifestyle‐related diseases, and adipose tissue and adipocyte research has been active. Glycosphingolipids are involved in the pathogenesis of type 2 diabetes induced by insulin resistance, but the details of the glycosphingolipid molecular species composition of adipocytes have yet to be elucidated. We used 3T3‐L1 adipocytes and the 1,2‐dichloroethane‐wash method to remove triacylglycerols, which are abundant in adipocytes, and analyzed the structures of glycosphingolipids, particularly neutral glycosphingolipids, using liquid chromatography–mass spectrometry.     

抗消化乙酰酯淀粉结构和结肠靶向性能研究

采用扫描电镜、X射线衍射和生物体外(In-V itro)降解等方法,对不同取代度DS的抗消化乙酰酯淀粉的颗粒形貌、结晶结构和生物降解性能进行了研究。结果表明:乙酰酯淀粉的颗粒表面变得粗糙并发生破损;随着乙酰基团取代度的增大,淀粉的抗消化性能不断提高,当DS>2时,淀粉中抗消化淀粉质量分数达到90%以上,其结晶结构也由A型向V型转变。生物体外降解试验表明,抗消化乙酰酯淀粉薄膜在模拟人体上消化道环境中的降解程度低于2.5%,在人工模拟结肠环境中的微生物降解程度为30%—50%,显示出潜在的结肠靶向性和微生物降解性。由此可见,抗消化乙酰酯淀粉适合作为菌群触发型口服结肠靶向药物控释载体材料。     

Comparative clinical wettability of teeth and intraoral mucosa

The observed reduced adhesiveness of human intraoral mucosa, as compared with adjacent teeth, was determined for 14 healthy humans to correlate with differing measured intraoral contact angles for a variety of otherwise non-interacting test liquids on these two equally water-wettable surfaces under clinical conditions. Measurements were made on the front maxillary tooth surfaces and the-inner lower lip mucosal surfaces of the same subjects, either immediately upon first exposure of the oral tissues or after 30-60 s drying in ambient air. Lower critical surface tensions were found for wet mucosal surfaces (25.4 mN/m) than for wet tooth surfaces (31.2 mN/m). Exposure to air for up to 1 min increased the mucosal critical surface tensions by only 2 mN/m, and had even less influence on the measured properties of tooth surfaces. These data suggest that the observed 'bioabhesive' surface quality of oral mucosa, retaining negligible plaque, is associated with its critical surface tension in the zone near 25 mN/m, as found earlier for the natural fouling-resistant surfaces of dolphins and killer whales.     

Enterohemorrhagic Escherichia coli and a Fresh View on Shiga Toxin-Binding Glycosphingolipids of Primary Human Kidney and Colon Epithelial Cells and Their Toxin Susceptibility

Enterohemorrhagic Escherichia coli (EHEC) are the human pathogenic subset of Shiga toxin (Stx)-producing E. coli (STEC). EHEC are responsible for severe colon infections associated with life-threatening extraintestinal complications such as the hemolytic-uremic syndrome (HUS) and neurological disturbances. Endothelial cells in various human organs are renowned targets of Stx, whereas the role of epithelial cells of colon and kidneys in the infection process has been and is still a matter of debate. This review shortly addresses the clinical impact of EHEC infections, novel aspects of vesicular package of Stx in the intestine and the blood stream as well as Stx-mediated extraintestinal complications and therapeutic options. Here follows a compilation of the Stx-binding glycosphingolipids (GSLs), globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) and their various lipoforms present in primary human kidney and colon epithelial cells and their distribution in lipid raft-analog membrane preparations. The last issues are the high and extremely low susceptibility of primary renal and colonic epithelial cells, respectively, suggesting a large resilience of the intestinal epithelium against the human-pathogenic Stx1a- and Stx2a-subtypes due to the low content of the high-affinity Stx-receptor Gb3Cer in colon epithelial cells. The review closes with a brief outlook on future challenges of Stx research.     

美羊羊与灰太狼

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