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排序方式: 共有1022条查询结果,搜索用时 812 毫秒
71.
L. Renee Ruhaak Evelyne Steenvoorden Carolien A. M. Koeleman André M. Deelder Manfred Wuhrer 《Proteomics》2010,10(12):2330-2336
Analysis of N‐glycans is often performed by LC coupled to fluorescence detection. The N‐glycans are usually labeled by reductive amination with a fluorophore containing a primary amine to allow fluorescence detection. Moreover, many of the commonly applied labels also allow improved mass spectrometric detection of oligosaccharides. For reductive amination, the amine group of the label reacts with the reducing‐end aldehyde group of the oligosaccharide to form a Schiff base, which is reduced to a secondary amine. Here, we propose the use of 2‐picoline‐borane as the reducing agent, as a non‐toxic alternative to the extensively used, but toxic sodium cyanoborohydride. Using dextran oligosaccharides and plasma N‐glycans, we demonstrate similar labeling efficacies for 2‐picoline‐borane and sodium cyanoborohydride. Therefore, 2‐picoline‐borane is a non‐toxic alternative to sodium cyanoborohydride for the labeling of oligosaccharides. 相似文献
72.
Ruhaak LR Hennig R Huhn C Borowiak M Dolhain RJ Deelder AM Rapp E Wuhrer M 《Journal of proteome research》2010,9(12):6655-6664
High-throughput methods for oligosaccharide analysis are required when searching for glycan-based biomarkers. Next to mass spectrometry-based methods, which allow fast and reproducible analysis of such compounds, further separation-based techniques are needed, which allow for quantitative analysis. Here, an optimized sample preparation method for N-glycan-profiling by multiplexed capillary gel electrophoresis with laser-induced fluorescence detection (CGE-LIF) was developed, enabling high-throughput glycosylation analysis. First, glycans are released enzymatically from denatured plasma glycoproteins. Second, glycans are labeled with APTS using 2-picoline borane as a nontoxic and efficient reducing agent. Reaction conditions are optimized for a high labeling efficiency, short handling times, and only limited loss of sialic acids. Third, samples are subjected to hydrophilic interaction chromatography (HILIC) purification at the 96-well plate format. Subsequently, purified APTS-labeled N-glycans are analyzed by CGE-LIF using a 48-capillary DNA sequencer. The method was found to be robust and suitable for high-throughput glycan analysis. Even though the method comprises two overnight incubations, 96 samples can be analyzed with an overall labor allocation time of 2.5 h. The method was applied to serum samples from a pregnant woman, which were sampled during first, second, and third trimesters of pregnancy, as well as 6 weeks, 3 months, and 6 months postpartum. Alterations in the glycosylation patterns were observed with gestation and time after delivery. 相似文献
73.
Ubaldo E Martinez-Outschoorn Renee M Balliet Dayana B Rivadeneira Barbara Chiavarina Stephanos Pavlides Chenguang Wang Diana Whitaker-Menezes Kristin M Daumer Zhao Lin Agnieszka K Witkiewicz Neal Flomenberg Anthony Howell Richard G Pestell Erik S Knudsen Federica Sotgia Michael P Lisanti 《Cell cycle (Georgetown, Tex.)》2010,9(16):3256-3276
Loss of stromal fibroblast caveolin-1 (Cav-1) is a powerful single independent predictor of poor prognosis in human breast cancer patients, and is associated with early tumor recurrence, lymph node metastasis and tamoxifen-resistance. We developed a novel co-culture system to understand the mechanism(s) by which a loss of stromal fibroblast Cav-1 induces a “lethal tumor microenvironment.” Here, we propose a new paradigm to explain the powerful prognostic value of stromal Cav-1. In this model, cancer cells induce oxidative stress in cancer-associated fibroblasts, which then acts as a “metabolic” and “mutagenic” motor to drive tumor-stroma co-evolution, DNA damage and aneuploidy in cancer cells. More specifically, we show that an acute loss of Cav-1 expression leads to mitochondrial dysfunction, oxidative stress and aerobic glycolysis in cancer associated fibroblasts. Also, we propose that defective mitochondria are removed from cancer-associated fibroblasts by autophagy/mitophagy that is induced by oxidative stress. As a consequence, cancer associated fibroblasts provide nutrients (such as lactate) to stimulate mitochondrial biogenesis and oxidative metabolism in adjacent cancer cells (the “Reverse Warburg effect”). We provide evidence that oxidative stress in cancer-associated fibroblasts is sufficient to induce genomic instability in adjacent cancer cells, via a bystander effect, potentially increasing their aggressive behavior. Finally, we directly demonstrate that nitric oxide (NO) over-production, secondary to Cav-1 loss, is the root cause for mitochondrial dysfunction in cancer associated fibroblasts. In support of this notion, treatment with anti-oxidants (such as N-acetyl-cysteine, metformin and quercetin) or NO inhibitors (L-NAME) was sufficient to reverse many of the cancer-associated fibroblast phenotypes that we describe. Thus, cancer cells use “oxidative stress” in adjacent fibroblasts (1) as an “engine” to fuel their own survival via the stromal production of nutrients and (ii) to drive their own mutagenic evolution towards a more aggressive phenotype, by promoting genomic instability. We also present evidence that the “field effect” in cancer biology could also be related to the stromal production of ROS and NO species. eNOS-expressing fibroblasts have the ability to downregulate Cav-1 and induce mitochondrial dysfunction in adjacent fibroblasts that do not express eNOS. As such, the effects of stromal oxidative stress can be laterally propagated, amplified and are effectively “contagious”—spread from cell-to-cell like a virus—creating an “oncogenic/mutagenic” field promoting widespread DNA damage.Key words: caveolin-1, cancer associated fibroblasts, oxidative stress, reactive oxygen species (ROS), mitochondrial dysfunction, autophagy, nitric oxide (NO), DNA damage, aneuploidy, genomic instability, anti-oxidant cancer therapy, the “field effect” in cancer biology 相似文献
74.
Stone KL Bjornson RD Blasko GG Bruce C Cofrancesco R Carriero NJ Colangelo CM Crawford JK Crawford JM daSilva NC Deluca JD Elliott JI Elliott MM Flory PJ Folta-Stogniew EJ Gulcicek E Kong Y Lam TT Lee JY Lin A LoPresti MB Mane SM McMurray WJ Tikhonova IR Westman S Williams NA Wu TL Hongyu Z Williams KR 《The Yale journal of biology and medicine》2007,80(4):195-211
75.
Arneson LN Brickshawana A Segovis CM Schoon RA Dick CJ Leibson PJ 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(6):3397-3401
Little is known about the regulatory roles of specific soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in cytotoxic lymphocytes. Recent information suggests that mutations in the SNARE protein syntaxin 11 result in a form of familial hemophagocytic lymphohistiocytosis (FHL). Because genetic abnormalities in key granule components (e.g., perforin) or in regulators of secretion (e.g., Munc13-4) underlie the other identified forms of FHL, we assessed whether syntaxin 11 might also serve a related regulatory role. We determined that syntaxin 11 is expressed in NK cells and activated CTLs and is located in discrete membrane-associated structures in the cytoplasm. Enhanced expression of syntaxin 11 augments the secretion and killing of tumor targets, and suppression of syntaxin 11 expression inhibits these functions. Our data identify and characterize a role for syntaxin 11 in granule exocytosis and in the generation of cell-mediated killing. These results also provide new insights on the mechanisms of hemopoietic dysregulation in FHL. 相似文献
76.
A genomewide association study of skin pigmentation in a South Asian population 总被引:4,自引:0,他引:4
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Stokowski RP Pant PV Dadd T Fereday A Hinds DA Jarman C Filsell W Ginger RS Green MR van der Ouderaa FJ Cox DR 《American journal of human genetics》2007,81(6):1119-1132
We have conducted a multistage genomewide association study, using 1,620,742 single-nucleotide polymorphisms to systematically investigate the genetic factors influencing intrinsic skin pigmentation in a population of South Asian descent. Polymorphisms in three genes—SLC24A5, TYR, and SLC45A2—yielded highly significant replicated associations with skin-reflectance measurements, an indirect measure of melanin content in the skin. The associations detected in these three genes, in an additive manner, collectively account for a large fraction of the natural variation of skin pigmentation in a South Asian population. Our study is the first to interrogate polymorphisms across the genome, to find genetic determinants of the natural variation of skin pigmentation within a human population. 相似文献
77.
78.
The positive impact of team-based virtual microscopy on student learning in physiology and histology
Team-based virtual microscopy and on-line learning were used to transform the first-year Physiology/Histology course at The Johns Hopkins School of Medicine into a student-centered learning environment. Prior to each laboratory session, students were required to view prelaboratory virtual lectures and examine digital slides that had been enhanced with annotations and 2-min microlectures. The laboratory classroom was then used for team-based learning exercises including student presentations and small-group discussions designed to integrate histology and physiology. The results of quantitative assessments indicated an 8- to 14-point increase over the identical final exams given over the past 5 yr. Means (+/-SD) of percent correct answers on the final exam were found to be 75.2% (11.1%), 72.5% (12.6%), 70.5% (12.6%), 73.6% (11.3%), 73.1% (12.2%), and 84.1% (9.1%) for years 2001-2006, respectively. The mean test scores for all other years were statistically lower compared with 2006, as determined by the Bonferroni post hoc multiple-comparison test (P < 0.001 for all years). 相似文献
79.
Commerford SR Vargas L Dorfman SE Mitro N Rocheford EC Mak PA Li X Kennedy P Mullarkey TL Saez E 《Molecular endocrinology (Baltimore, Md.)》2007,21(12):3002-3012
The liver X receptors (LXRalpha and beta) are nuclear receptors that coordinate carbohydrate and lipid metabolism. Treatment of insulin-resistant mice with synthetic LXR ligands enhances glucose tolerance, inducing changes in gene expression expected to decrease hepatic gluconeogenesis (via indirect suppression of gluconeogenic enzymes) and increase peripheral glucose disposal (via direct up-regulation of glut4 in fat). To evaluate the relative contribution of each of these effects on whole-body insulin sensitivity, we performed hyperinsulinemic-euglycemic clamps in high-fat-fed insulin-resistant rats treated with an LXR agonist or a peroxisome proliferator-activated receptor gamma ligand. Both groups showed significant improvement in insulin action. Interestingly, rats treated with LXR ligand had lower body weight and smaller fat cells than controls. Insulin-stimulated suppression of the rate of glucose appearance (Ra) was pronounced in LXR-treated rats, but treatment failed to enhance peripheral glucose uptake (R'g), despite increased expression of glut4 in epididymal fat. To ascertain whether LXR ligands suppress hepatic gluconeogenesis directly, mice lacking LXRalpha (the primary isotype in liver) were treated with LXR ligand, and gluconeogenic gene expression was assessed. LXR activation decreased expression of gluconeogenic genes in wild-type and LXRbeta null mice, but failed to do so in animals lacking LXRalpha. Our observations indicate that despite inducing suggestive gene expression changes in adipose tissue in this model of diet-induced insulin resistance, the antidiabetic effect of LXR ligands is primarily due to effects in the liver that appear to require LXRalpha. These findings have important implications for clinical development of LXR agonists as insulin sensitizers. 相似文献
80.