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  • 1
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    RIPK1 ensures intestinal homeostasis by protecting the epithelium against apoptosis (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-09-05
    Description: Receptor interacting protein kinase 1 (RIPK1) has an essential role in the signalling triggered by death receptors and pattern recognition receptors. RIPK1 is believed to function as a node driving NF-kappaB-mediated cell survival and inflammation as well as caspase-8 (CASP8)-dependent apoptotic or RIPK3/MLKL-dependent necroptotic cell death. The physiological relevance of this dual function has remained elusive because of the perinatal death of RIPK1 full knockout mice. To circumvent this problem, we generated RIPK1 conditional knockout mice, and show that mice lacking RIPK1 in intestinal epithelial cells (IECs) spontaneously develop severe intestinal inflammation associated with IEC apoptosis leading to early death. This early lethality was rescued by antibiotic treatment, MYD88 deficiency or tumour-necrosis factor (TNF) receptor 1 deficiency, demonstrating the importance of commensal bacteria and TNF in the IEC Ripk1 knockout phenotype. CASP8 deficiency, but not RIPK3 deficiency, rescued the inflammatory phenotype completely, indicating the indispensable role of RIPK1 in suppressing CASP8-dependent apoptosis but not RIPK3-dependent necroptosis in the intestine. RIPK1 kinase-dead knock-in mice did not exhibit any sign of inflammation, suggesting that RIPK1-mediated protection resides in its kinase-independent platform function. Depletion of RIPK1 in intestinal organoid cultures sensitized them to TNF-induced apoptosis, confirming the in vivo observations. Unexpectedly, TNF-mediated NF-kappaB activation remained intact in these organoids. Our results demonstrate that RIPK1 is essential for survival of IECs, ensuring epithelial homeostasis by protecting the epithelium from CASP8-mediated IEC apoptosis independently of its kinase activity and NF-kappaB activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Takahashi, Nozomi -- Vereecke, Lars -- Bertrand, Mathieu J M -- Duprez, Linde -- Berger, Scott B -- Divert, Tatyana -- Goncalves, Amanda -- Sze, Mozes -- Gilbert, Barbara -- Kourula, Stephanie -- Goossens, Vera -- Lefebvre, Sylvie -- Gunther, Claudia -- Becker, Christoph -- Bertin, John -- Gough, Peter J -- Declercq, Wim -- van Loo, Geert -- Vandenabeele, Peter -- England -- Nature. 2014 Sep 4;513(7516):95-9. doi: 10.1038/nature13706.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] VIB Inflammation Research Center, Technologiepark 927, B-9052 Ghent, Belgium [2] Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium. ; Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, Pennsylvania 19426, USA. ; 1] VIB Inflammation Research Center, Technologiepark 927, B-9052 Ghent, Belgium [2] Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium [3] VIB Bio Imaging Core Gent, Technologiepark 927, B-9052 Ghent, Belgium. ; Department of Medicine 1, Friedrich-Alexander-University, D-91054 Erlangen, Germany. ; 1] VIB Inflammation Research Center, Technologiepark 927, B-9052 Ghent, Belgium [2] Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium [3] Methusalem program, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25186904" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anti-Bacterial Agents/pharmacology ; *Apoptosis/drug effects ; Caspase 8/genetics/metabolism ; Cell Survival/drug effects ; Epithelial Cells/*cytology/drug effects/*metabolism/pathology ; Epithelium/drug effects/*metabolism/pathology ; Female ; Gene Deletion ; *Homeostasis/drug effects ; Inflammation/metabolism/pathology ; Intestines/*cytology/drug effects/*metabolism/pathology ; Male ; Mice ; Mice, Knockout ; Myeloid Differentiation Factor 88/deficiency ; NF-kappa B/metabolism ; Necrosis ; Organoids/cytology/drug effects/enzymology/metabolism ; Protein Kinases/metabolism ; Receptor-Interacting Protein Serine-Threonine ; Kinases/deficiency/genetics/*metabolism ; Receptors, Tumor Necrosis Factor, Type I/deficiency ; Survival Analysis ; Tumor Necrosis Factors/pharmacology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
    Electronic Resource
    Electronic Resource
    Calibration and mass measurement in negative-ion fast-atom bombardment mass spectrometryNRCC No. 32989. (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 538-542 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The problem of acceptable accuracy in mass calibration for fast-atom bombardment (FAB) mass spectrometry has recently received some attention (K. Véekey, Rapid Commun. Mass Spectrom., 2, 213 (1988); Idem., Org. Mass Spectrom., 24, 183 (1989). We describe here a calibration method for negative-ionFAB, using gold cluster ions, which provides facile mass calibration over the range from can 200u to 10000u. Under suitable conditions, it is possible to use these ions as internal standards for accurate mass measurement.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290051111
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of trifluoroacetic acid on the reduction of disulfide bridges in peptides analyzed by fast-atom bombardment mass spectrometry (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 390-395 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Some of the factors that influence the reduction of disulfide-containing peptides under fast-atom bombardment have been investigated using two neurohormonal peptides that include disulfide bridges in their structures. Deaminoarginine-vasopressin (DAVP) and arginine-vasopressin (AVP) have been analyzed as their acetate and trifluoroacetate salts. Results obtained in a thioglycerol matrix indicate that the peptides analyzed as their acetate salts are completely reduced under bombardment, whereas the trifluoroacetate salts show little evidence of reduction. Addition of trifluoroacetic acid to the acetate sample prior to bombardment inhibits reduction whereas addition after bombardment shows no effect on the reduction, thereby indicating the irreversibility of the process. Time-monitoring experiments conducted with the acetate salts of DAVP and AVP in common matrices such as thioglycerol, dithiothreitol + diethioerythritol, glycerol, hydroxyethyldisulfide and nitrobenzyl-alcohol demonstrate an important effect of the chemical nature of the matrix on reduction. In matrices containing thiol groups, the reduction is extensive, whereas it is almost suppressed in matrices such as hydroxyethyldisulfide and nitrobenzylalcohol. However, the addition of trifluoroacetic acid to all of these matrices essentially eliminates reduction and provides measured isotopic peak ratios that are in agreement with theoretically calculated values for these peptides.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290031105
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  • 4
    Electronic Resource
    Electronic Resource
    An investigation of fragmentation mechanisms of doubly protonated tryptic peptidesNRCC No. 34818 (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 651-657 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Peptides formed as reaction products, of specific hydrolysis of proteins by trypsin, are characterized by a basic residue (Arg or Lys) as the C-terminus, which facilitates formation of bundant [M+2H]2+ ions under electrospray r ionspry conditions. These doubly charged ions readily dissociate upon collisional activation to y" and b fragment ions which are mass complemens of one another. The suggestion tht these fragments are formed by direct charge-separation disociatons must contend with the observation that the y" intensities are generaly appreciably larger than those of their b counterparts. However, it is shown that this can be accouned for by a greater susceptibility f the b ions to undergo further dissociaton to smaler fragments such as immonium ions. In addition no evidence could be found to support alternative mechanisms, including dissociative electron capture, for which equal intensities of the two fragment ion series are not obligatory. Initial protonation at the N-terminus was shown to be required for formation of these [M+2H]2+ ions via its suppression by mono-acetylation at the N-terminus. These findings, and others concerning formation of [y"′]2+ fragments from singly protonated peptides, via charge-site-induced cleavages and intramolecular proto transfers between nitrogen atoms, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290061105
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  • 5
    Electronic Resource
    Electronic Resource
    Charge promotion of low-energy fragmentations of peptide ions (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 658-662 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have examined the hypothesis that structural features which predispose to localization of charge at a strongly favored site are not conducive to the low-energy fragmentation of peptide ions via a multiplicity of pathways. Consistent with this proposal, it is demonstrated that the formation of N- or C-terminal pre-charged derivatives is detrimenal to the formation of sequence-specific product ions following low-energy collisional activation. Protonation of pre-charged derivatives (yielding doubly charged ions) restores favorable fragmentation properties; the effect is attributed to the fragmentation-directing properties of the proton whih may occupy one of several sites. Similarly, a doubly protonated peptide which incorporates a C-terminal arginine residue as a single strongly favored site of protonation exhibits favored low-energy fragmentations attributable to locaton of he second proton at one of several sites remote from the C-terminus.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290061106
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  • 6
    Electronic Resource
    Electronic Resource
    Investigation of the ionization processes occurring in liquid-assisted secondary ion mass spectrometry of derivatized monosaccharides (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1329-1339 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several derivatized monosaccharides, the 2-deoxy-D-ribofuranoses, have been studied by liquid-assisted secondary ion mass spectrometry (LSIMS) in order to gain insight into the factors affecting ionization in FAB/LSIMS. Examination of the mass spectra for these compounds obtained in eight liquid matrices (diethanolamine, ethylene glycol, glycerol, 2-hydroxyethyl disulfide, 2-hydroxyphenethyl alcohol, 3-nitrobenzyl alcohol, sulfolane and thioglycerol) reveals that in all cases the anomalous [M - H]+ ion is the predominant species in the molecular ion region and that [M + Na]+ species are observed in the presence of Na+. The analysis of these compounds by chemical ionization with ammonia shows [M + H]+ as the major species while [M - H]+ is essentially absent. This indicates that the ionization processes occurring in the two techniques are not analogous. Thermodynamic considerations based on the gas-phase hydride ion affinities of the protonated matrices do not support a predominant gas-phase mechanism for the formation of [M - H]+ in LSIMS. However, it is possible using solvation energies to rationalize the formation of [M - H]+ in terms of condensed-phase ionization processes which take place either in the liquid matrix or in the dense selvedge region immediately above the surface where extensive solvation is present. Electrospray data obtained for one of the derivatized monosaccharides indicates that the [M - H]+ is not performed in the condensed phase in LSIMS and that it is the product of fast ion beam-induced processes. While the nature of the matrix is seen to have little effect on the intensities of [M - H]+ and [M + H]+ it is observed to be an important factor for the intensity of M+· for one of the monosaccharides. This effect can be related to the electron-scavenging properties of the matrices and reinforces the hypothesis that condensed phase processes are significant in ionization.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210281108
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  • 7
    Electronic Resource
    Electronic Resource
    Systematic study of the effects of experimental parameters on the beam-induced dehalogenation of chlorpromazine in liquid secondary ion mass spectrometry (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 18-25 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of experimental parameters such as time of irradiation, analyte concentration, primary beam density, matrix selection and matrix additives on the beam-induced dehalogenation of chlorpromazine in liquid secondary ion mass spectrometry (LSIMS) was investigated. It was found that dehalogenation of chlorpromazine in glycerol increased with increasing time of irradiation, analyte concentration and primary beam density. These results were compared with those obtained using 4-chlorophenylalanine ethyl ester and the differences observed were rationalized in terms of compound surface activity. Evidence is given that matrix selection is the key experimental parameter affecting the extent of beam-induced dehalogenation of chlorpromazine in LSIMS. Of the eleven matrices used, the greatest extent of dehalogenation was observed in glycerol. Sulfur-containing matrices consistently exhibited a lower extent of dehalogenation than oxygen-containing aliphatic matrices, implying that sulfur is implicated in mitigating the reduction process. Dehalogenation was totally inhibited in 2-hydroxyethyl disulfide, 4-hydroxybenzenesulfonic acid and 3-nitrobenzyl alcohol. Similarly, the use of matrix additives such as 3-nitrobenzyl alcohol and trifluoroacetic acid was found to be useful in inhibiting the extent of dehalogenation occurring in glycerol.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210290104
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of the empirical formula of peptides by fast atom bombardment mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 249-256 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for calculating the empirical formulae of peptides from mass spectrometric data is described. Exact mass measurement data and isotopic peak ratios are used to generate a list of potential empirical formulae that fit a given compound within experimental error. The formulae are then analysed by a mathematical algorithm and only those corresponding to chain peptides formed from the basic amino acids are retained. Calculations conducted for typical peptides indicate that the approach may be useful for peptide identification if the experimental values are determined within an acceptable range of errors. Experimental measurements of the exact mass and isotopic peak ratios made using typical peptides demonstrate the feasibility of the approach.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140602
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  • 9
    Electronic Resource
    Electronic Resource
    A comparative study of methyl ester trimethylsilyl, allyldimethylsilyl and tert-butyldimethylsilyl ethers for electron impact mass spectrometry of leukotrienes (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 313-323 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic and mass spectrometric properties of leukotriene B4, 20-hydroxy-leukotriene B4 and 20-carboxy-leukotriene-B4 were investigated as their methyl ester trimethylsilyl, methyl ester allyldimethylsilyl and methyl ester tert-butyldimethylsilyl ethers. The gas chromatographic properties of the trimethylsilyl and tert-butyldimethylsilyl ether derivatives were good with respect to peak shape and sensitivity, whereas the allyldimethylsilyl ether derivative gave a lower sensitivity. The sensitivity defined as the quantity that could be passed through the gas chromatographic column.The three derivatives showed a mass spectrometric fragmentation pattern with cleavage of the C12—C13 bond as an important feature. Particularly, the allyldimethylsilyl ether derivative of the three compounds studied exhibited a high tendency for C12—C13 bond cleavage resulting in a fairly intense ion at m/z 435. However, the mass spectra indicated multiple fragmentation pathways due to the presence of double bonds, leading to decreased intensities of the high mass ions. A quantitative analysis by selected ion monitoring of the most intense high mass ions in the respective mass spectrum demonstrated that neither derivative would allow measurements in the low picogram range. Catalytic hydrogenation of the double bonds was performed and the methyl ester trimethylsiyl, methyl ester allyldimethylsilyl and methyl ester tert-butyldimethylsilyl ether derivatives of the reduced compounds were prepared. Saturation of the double bonds increased the gas chromatographic sensitivity for the three derivatives as well as the intensities of the high mass ions in their mass spectra. The high sensitivity that can be obtained by measurement of such high mass ions was demonstrated by quantification of leukotriene B4 in lung tissue samples by selected ion monitoring.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140704
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  • 10
    Electronic Resource
    Electronic Resource
    Mass spectrometry of prostaglandins, leukotrienes and steroids as their allyldimethylsilyl ether derivatives (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 657-661 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Allyldimethylsilyl ethers of prostaglandin E2 and F2α, leukotriene B4 and 5β-pregnane-3α, 20α-diol were prepared at room temperature in good yields with the novel reagent N, O-bis(allyldimethylsilyl)-trifluoroacetamide. The gas chromatographic properties of the derivatives of prostaglandins and the steroid were found to be excellent whereas those of leukotriene B4 were found to be less than satisfactory. The mass spectra of the allyldimethylsilyl ether derivatives of the compounds studied show intense ions in their upper mass region derived from the elimination of an allyl radical. In the mass spectrum of the derivative of leukotriene B4, the formation of a conjugated carbonium ion by α-cleavage is a major process. The detection limits for a quantitative assay were established by performing selected ion monitoring on the most intense ion in the upper mass region of respective mass spectrum. Detection limits in the low picogram range were obtained for the prostaglandins and the steroid but the allyldimethylsilyl ether derivative of leukotriene B4 exhibited a far higher detection limit. It is concluded for the latter compound that the detection limit depends primarily on the gas chromatographic properties.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200131204
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