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  • 2004  (10)
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  • 2004  (10)
  • 1
    Language: English
    In: Current Biology, 29 December 2004, Vol.14(24), pp.2271-2276
    Description: More than 60 small RNAs (sRNA) have been identified in E. coli [1–7] . The functions of the majority of these sRNAs are still unclear. For the few sRNAs characterized, expression and functional studies indicate that they act under stress conditions [8–14] . Here, we describe a novel E. coli chromosome locus that is part of the SOS response to DNA damage. This locus encodes two sRNAs, IstR-1 and IstR-2, and a toxic peptide, TisB, encoded by tisAB mRNA. Transcription of tisAB and istR -2 is SOS regulated, whereas IstR-1 is present throughout growth. IstR-1 inhibits toxicity by base-pairing to a short region in the tisAB mRNA. This antisense interaction entails RNase III-dependent cleavage, thereby inactivating the mRNA for translation. In the absence of the SOS response, IstR-1 is present in high excess over its target. However, SOS induction leads to depletion of the IstR-1 pool, concomitant with accumulation of tisAB mRNA. Under such conditions, TisB exerts its toxic effect, slowing down growth. We propose that the inhibitory sRNA prevents inadvertent TisB synthesis during normal growth and, possibly, also limits SOS-induced toxicity. Our study adds the SOS regulon to the growing list of global regulatory circuits controlled by sRNA genes.
    Keywords: Natural Sciences ; Biological Sciences ; Naturvetenskap ; Biologiska Vetenskaper ; Amino Acid Sequence ; Base Sequence ; Blotting; Northern ; Comparative Study ; Escherichia Coli/*Genetics ; Gene Expression Regulation; Bacterial ; Models; Genetic ; Molecular Sequence Data ; Peptides/Genetics/*Metabolism/Toxicity ; Rna; Bacterial/*Genetics ; Rna; Messenger/Genetics/*Metabolism ; Research Support; Non-U.S. Gov'T ; Research Support; U.S. Gov'T; Non-P.H.S. ; Sos Response (Genetics)/Genetics/*Physiology;
    ISSN: 0960-9822
    E-ISSN: 18790445
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  • 2
    Language: English
    In: Tetrahedron, 2004, Vol.60(11), pp.2601-2608
    Description: The β-galactosidase from bovine testes (EC 3.2.1.23) promotes the transfer of a galactose unit to glucose or galactose-containing residues in manifold derivatives, establishing β1→3 linkages. The synthesis of several potentially biologically important oligosaccharides β- d -Gal p -(1→3)-α- d -Glc p -(1→2)-β- d -Fru f 2 , β- d -Gal p -(1→3)-β- d -Gal p -(1→4)-α,β- d -Glc p 4 , β- d -Gal p -(1→3)-α- d -Glc p -(1→4)- d -Glc p -ol/Man p -ol 6 , β- d -Gal p -(1→3)-α- d -Glc p -(1→6)-β- d -Fru f 8 , β- d -Gal p -(1→3)-α- d -Glc p -(1→6)-[α- d -Glc p -(1↔2)]-β- d -Fru f 10 , α- d -Gal p -(1→6)-[β- d -Gal p -(1→3)]-α- d -Glc p -(1↔2)-β- d -Fru f 12 , β- d -Gal p -(1→3)-α- d -Glc p -(1↔2)-β- d -Fru f -(1↔2)-β- d -Fru f 14 has been reached in yields between 7 and 44% by implementation of this specific enzyme. In addition, we found that it is feasible to gain high yields without an enzyme-specific buffer and even making upscaled preparation on a gram scale. Graphic
    Keywords: Novel Food Components ; Regioselective Galactosylation ; Enzyme ; Bovine Testes ; Upscaled Enzymatic Reaction Devoid of Buffer
    ISSN: 0040-4020
    Source: ScienceDirect (Elsevier B.V.)
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  • 3
    Language: English
    In: International Journal of Cancer, 10 December 2004, Vol.112(5), pp.815-822
    Description: CD97 is an EGF‐TM7 receptor found on various carcinomas where expression levels correlate with dedifferentiation and tumor stage, smooth muscle cells and leukocytes. CD97 acts as an adhesion molecule by binding to its cellular ligand, CD55. In this study, we demonstrate that 2 immunodominant CD97 epitopes are not equally present in the various cell types. Differences were apparent in gastrointestinal tumors and smooth muscle cells where monoclonal antibodies (mAbs) to the first epidermal growth factor (EGF) domain (CD97) showed a more restricted staining pattern than mAbs to the stalk region (CD97). This discrepancy was not detectable in cultured gastrointestinal tumor cell lines. In fact, the selection of the CD97 mAb influences the result of clinical studies. Thus, we clarified the reason(s) for these differences in CD97 mAb staining on various cell types. We provide evidence that epitope accessibility for CD97 mAbs depends on N‐glycosylation. Immunoprecipitation of CD97 from the Colo 205 tumor cell line revealed the established 78 and 83 kDa products, while a 52 and 57 kDa band were obtained from smooth muscle cells. N‐glycosidase F reduced the size of CD97 in Colo 205 cells to 52–57 kDa. Culturing these cells with tunicamycin resulted in the same decrease in size and impaired CD97 mAb binding. As shown by site‐directed mutagenesis, deletion of the N‐glycosylation sites located within the EGF domains efficiently disturbed CD97 mAb immunoreactivity and, importantly, binding of CD55. In conclusion, CD97 epitope accessibility for mAbs and ligand binding is influenced by cell type‐specific N‐glycosylation. © 2004 Wiley‐Liss, Inc.
    Keywords: Cd97 ; Colorectal Cancer ; Smooth Muscle Cell ; Epitope Accessibility ; Glycosylation
    ISSN: 0020-7136
    E-ISSN: 1097-0215
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  • 4
    Language: English
    In: European Journal of Pharmaceutics and Biopharmaceutics, 2004, Vol.57(2), pp.369-375
    Description: Nanoparticles represent promising carriers for controlled drug delivery. This work focuses on the size and molecular mass characterization of polyalkylcyanoacrylate nanoparticles formed by anionic emulsion polymerization of butylcyanoacrylate in the presence of poloxamer 188 as a stabilizer. Three different methods were used to determine the size and size distribution of the particle populations: scanning electron microscopy (SEM), dynamic light scattering (DLS), and analytical ultracentrifugation (ANUC). SEM on freeze-dried and Au-shadowed samples showed a relatively narrow distribution of virtually spherical particles with a mean diameter of 167 nm. DLS yielded a monomodal distribution with hydrodynamic diameters around 199 nm (in the absence of additional stabilizer) or 184 nm (in the presence of 1% poloxamer 188). The size distribution determined by ANUC using sedimentation velocity analysis was somewhat more complex, the size of the most abundant particles being around 184 nm. Molar particle mass distributions centered around 2.3×10 9 g/mol. The advantages and disadvantages of the three sizing techniques are discussed.
    Keywords: Nanoparticles ; Polyalkylcyanoacrylate ; Particle Size ; Molecular Weight ; Analytical Ultracentrifugation ; Dynamic Light Scattering ; Electron Microscopy
    ISSN: 0939-6411
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  • 5
    In: Class.Quant.Grav. 22 (2005) 1769-1793
    Description: The divergence of the constraint quantities is a major problem in computational gravity today. Apparently, there are two sources for constraint violations. The use of boundary conditions which are not compatible with the constraint equations inadvertently leads to 'constraint violating modes' propagating into the computational domain from the boundary. The other source for constraint violation is intrinsic. It is already present in the initial value problem, i.e. even when no boundary conditions have to be specified. Its origin is due to the instability of the constraint surface in the phase space of initial conditions for the time evolution equations. In this paper, we present a technique to study in detail how this instability depends on gauge parameters. We demonstrate this for the influence of the choice of the time foliation in context of the Weyl system. This system is the essential hyperbolic part in various formulations of the Einstein equations. Comment: 25 pages, 5 figures; v2: small additions, new reference, publication number, classification and keywords added, address fixed; v3: update to match journal version
    Keywords: General Relativity And Quantum Cosmology
    Source: Cornell University
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  • 6
    Language: English
    In: ChemInform, 29 June 2004, Vol.35(26), pp.no-no
    Keywords: Carbohydrates ; Biochemical Syntheses ; Microbiological Syntheses ; Food Chemistry ; General ; Luxury Foods And Drinks ; Foodstuffs
    ISSN: 0931-7597
    E-ISSN: 1522-2667
    Source: John Wiley & Sons, Inc.
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  • 7
    Language: English
    In: Applied Catalysis A, General, 2004, Vol.269(1), pp.53-61
    Description: Technical catalysts for partial oxidation of acrolein to acrylic acid are based on Mo/V mixed oxides. Different preparation steps are characterised starting from solutions of ammonium-heptamolybdate and -metavanadate. These were dried, employing spray drying and crystallisation method followed by calcination. The materials formed at each preparation step were studied using X-ray powder diffraction, thermal decomposition, TG/DTA-MS and temperature programmed reduction (with H 2 and acrolein). X-ray diffraction revealed that the drying method affects structural composition of the binary Mo/V-oxides. Spray drying results preferably in a hexagonal MoO 3 -type phase, whereas crystallisation leads to V 2 O 5 -type structure. A correlation of the applied drying method and therefore of structural composition with catalytic performance is discussed by means of TPR investigation comparing the activation process of the two probe molecules H 2 and acrolein. Generally, spray dried samples are more active. The preparation variant via spray drying of precursor solution establishes a highly reproducible as well as promising basis for a specific focussing on the genesis of mostly metastable structure parts, which play a crucial role in heterogeneous catalysis.
    Keywords: Acrolein ; Acrylic Acid ; Molybdenum ; Vanadium ; Spray Drying ; Preparation ; Oxides
    ISSN: 0926-860X
    E-ISSN: 18733875
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  • 8
    Language: German
    In: Psychiatrische Praxis, November 2004, Vol.31 Suppl 1, pp.S73-5
    Description: To describe differences in cerebral glucose metabolism between frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD). 14 patients with FTLD (7 f/7 m, mean age 60.1 years) and 14 patients with AD (7 f/7 m, mean age 59.5 years) were examined. [18F]FDG positron emission tomography (PET) scans were analysed with statistical nonparametric mapping (SnPM) and statistical parametric mapping (SPM99). Significant decreases in glucose metabolism in FTLD compared to AD were detected in the left insula/left inferior frontal gyrus (Brodman area [BA]13, 45 and 47) and in the medial frontal gyrus bilaterally (BA10). A significant decrease in AD compared to FTLD was identified in the right middle temporal gyrus (BA39). Cerebral PET could be a promising tool to discriminate FTLD from AD.
    Keywords: Positron-Emission Tomography ; Alzheimer Disease -- Diagnostic Imaging ; Blood Glucose -- Metabolism ; Cerebral Cortex -- Diagnostic Imaging ; Dementia -- Diagnostic Imaging
    ISSN: 0303-4259
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 9
    Language: English
    In: Journal of Molecular Catalysis. A, Chemical, 2004, Vol.216(1), pp.67-74
    Description: The correlation of the structure and the catalytic activity of vanadium molybdenum oxide catalysts were examined by X-ray diffraction and temperature programmed reduction measurements. The experiments revealed the presence of two metastable vanadium molybdenum mixed oxides, h-(V,Mo)O 3 and (V,Mo) 2 O 5 , and an optimal vanadium molybdenum ratio of 3:7 for the yield of acrylic acid for acrolein. Vanadium molybdenum mixed oxides are used for the technical production of acrylic acid by partial oxidation of acrolein. Although this industrial process is established since several years, the catalytic mechanism is not known in detail. For an improved understanding of the reaction on a microscopic scale, we used subsystems such as V–Mo-oxides without additional promoters as model catalyst. Three series of mixed oxides with the chemical composition V x Mo y O z , x + y =1, were prepared; one by melting the pure oxides, one by crystallisation and another by spray-drying of ammonium salt precursors and subsequent calcination. The phases were analysed by X-ray diffraction. Most of the samples consist of two different vanadium molybdenum mixed oxides, a hexagonal h-(V,Mo)O 3 and a (V,Mo) 2 O 5 -phase, which is structurally related to vanadium pentoxide. The stability and the transformation of these phases were also examined. The selectivity and conversion rate for the partial oxidation of acrolein to acrylic acid was determined by temperature programmed reduction (TPR) to optimise the vanadium molybdenum ratio for an efficient catalytic phase. The results indicate a vanadium to molybdenum ratio of 3:7 as the most promising with respect to selectivity and activity at low temperatures.
    Keywords: Vanadium Molybdenum Oxides ; Heterogeneous Catalysis ; Acrolein ; Xrd ; Tpr
    ISSN: 1381-1169
    Source: ScienceDirect (Elsevier B.V.)
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  • 10
    Language: German
    In: Psychiat Prax, 2004, Vol.31, pp.73-75
    Description: Zusammenfassung Mittels Positronenemissionstomographie (PET) sollten zerebrale Regionen identifiziert werden, in denen sich Demenzen aus der Gruppe der frontotemporalen lobären Degenerationen (FTLD) in ihrem Glukosestoffwechsel von der Alzheimer-Krankheit (AD) unterscheiden. Es wurden je 14 Patienten mit der klinischen Diagnose FTLD bzw. AD untersucht. Signifikante Unterschiede zeigten sich in der linken Insula, im Gyrus frontalis medialis beidseits und im rechten Gyrus temporalis medialis. Die PET könnte daher ein viel versprechender Baustein bei der Differenzialdiagnose dieser demenziellen Syndrome sein.
    Description: Objective: To describe differences in cerebral glucose metabolism between frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD). Methods: 14 patients with FTLD (7 f/7 m, mean age 60.1 years) and 14 patients with AD (7 f/7 m, mean age 59.5 years) were examined. [18F]FDG positron emission tomography (PET) scans were analysed with statistical nonparametric mapping (SnPM) and statistical parametric mapping (SPM99). Results: Significant decreases in glucose metabolism in FTLD compared to AD were detected in the left insula/left inferior frontal gyrus (Brodman area [BA]13, 45 and 47) and in the medial frontal gyrus bilaterally (BA10). A significant decrease in AD compared to FTLD was identified in the right middle temporal gyrus (BA39). Conclusion: Cerebral PET could be a promising tool to discriminate FTLD from AD.
    ISSN: 1611-8332
    E-ISSN: 1611-8340
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