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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 90 (2004), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The deposition of amyloid β-protein in the brain is a fundamental process in the development of Alzheimerís disease; however, the mechanism underlying aggregation of amyloid β-protein remains to be determined. Here, we report that a membrane-mimicking environment, generated in the presence of detergents or a ganglioside, is sufficient per se for amyloid fibril formation from soluble amyloid β-protein. Furthermore, hereditary variants of amyloid β-protein, which are caused by amyloid precursor protein gene mutations, including the Dutch (E693Q), Flemish (A692G) and Arctic (E693G) types, show mutually different aggregation behavior in these environments. Notably, the Arctic-type amyloid β-protein, in contrast to the wild-type and other variant forms, shows a markedly rapid and higher level of amyloid fibril formation in the presence of sodium dodecyl sulfate or GM1 ganglioside. These results suggest that there are favorable local environments for fibrillogenesis of amyloid β-protein.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural & molecular biology 14 (2007), S. 332-340 
    ISSN: 1545-9985
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Polyglutamine (polyQ) diseases are classified as conformational neurodegenerative diseases, like Alzheimer and Parkinson diseases, and they are caused by proteins with an abnormally expanded polyQ stretch. However, conformational changes of the expanded polyQ protein and the toxic conformers formed ...
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural biology 9 (2002), S. 332-336 
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Despite numerous efforts, the lack of detailed structural information on amyloid fibrils has hindered clarification of the mechanism of their formation. Here, we describe a novel procedure for characterizing the conformational flexibility of β2-microglobulin amyloid fibrils at single-residue ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We present a patient with a large tumor embolus attached to a pacemaker electrode leading to multiple pulmonary emboli. At postmortem examination, this thrombus was composed of clusters of well-differentiated squamous cell carcinoma intermingled with fibrin. Tumor involvement was not evident in the myocardium, endocardium, or epicardium. The primary tumor was discovered in the lower intrathoracic esophagus. Tumor microamboli from the esophageal primary lesions may have accumulated around the pacemaker electrode due to turbulent flow in this region, producing a large and friable tumor embolus.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Iron as well as aluminum is reported to accumulate in neurons with neurofibrillary tangles (NFTs) of Alzheimer's disease (AD) brain. Previously we demonstrated that aluminum (III) shows phosphate-dependent binding with hyperphosphorylated τ (PHFτ), the major constituent of NFTs, thereby inducing aggregation of PHFτ. Herein we report that iron (III) can also induce aggregation of soluble PHFτ. Importantly, for the aggregation of PHFτ to occur, iron in the oxidized state (III) is essential since iron in the reduced state (II) lacks such ability. Furthermore, iron (III)-induced aggregation is reversed by reducing iron (III) to iron (II). Thus the iron-participating aggregation is mediated not only by τ phosphorylation but also by the transition of iron between reduced (II) and oxidized (III) states. Further incubation of insoluble PHFτ aggregates isolated from AD brain with reducing agents produced liberation of solubilized PHFτ and iron (II), indicating that PHFτ in association with iron (III) constitutes the insoluble pool of PHFτ. These results indicate that iron might play a role in the aggregation of PHFτ leading to the formation of NFTs in AD brain.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 81 (2002), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Inhibition of the accumulation of amyloid β-peptide (Aβ) and the formation of β-amyloid fibrils (fAβ) from Aβ, as well as the degradation of pre-formed fAβ in the CNS would be attractive therapeutic objectives for the treatment of Alzheimer's disease (AD). We previously reported that nordihydroguaiaretic acid (NDGA) inhibited fAβ formation from Aβ(1–40) and Aβ(1–42) dose-dependently in the range of 10–30 µmin vitro. Utilizing fluorescence spectroscopic analysis with thioflavin T and electron microscopic study, we show here that NDGA dose-dependently breaks down fAβ(1–40) and fAβ(1–42) within a few hours at pH 7.5 at 37°C. At 4 h, the fluorescence of fAβ(1–40) and fAβ(1–42) incubated with 50 µm NDGA was 5% and 10% of the initial fluorescence, respectively. The activity of NDGA to break down these fAβs was observed even at a low concentration of 0.1 µm. At 1 h, many short, sheared fibrils were observed in the mixture incubated with 50 µm NDGA, and at 4 h, the number of fibrils reduced markedly, and small amorphous aggregates were observed. We next compared the activity of NDGA to break down fAβ(1–40) and fAβ(1–42), with other molecules reported to inhibit fAβ formation from Aβ and/or to degrade pre-formed fAβ both in vivo and in vitro. At a concentration of 50 µm, the overall activity of the molecules examined in this study was in the order of: NDGA 〉〉 rifampicin = tetracycline 〉 poly(vinylsulfonic acid, sodium salt) = 1,3-propanedisulfonic acid, disodium salt 〉 β-sheet breaker peptide (iAβ5). In cell culture experiments, fAβ disrupted by NDGA were less toxic than intact fAβ, as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Although the mechanisms by which NDGA inhibits fAβ formation from Aβ, as well as breaking down pre-formed fAβin vitro, are still unclear, NDGA could be a key molecule for the development of therapeutics for AD.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 86 (2003), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 87 (2003), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cerebral deposition of amyloid β-peptide (Aβ) in the brain is an invariant feature of Alzheimer's disease (AD). A consistent protective effect of wine consumption on AD has been documented by epidemiological studies. In the present study, we used fluorescence spectroscopy with thioflavin T and electron microscopy to examine the effects of wine-related polyphenols (myricetin, morin, quercetin, kaempferol (+)-catechin and (–)-epicatechin) on the formation, extension, and destabilization of β-amyloid fibrils (fAβ) at pH 7.5 at 37°C in vitro. All examined polyphenols dose-dependently inhibited formation of fAβ from fresh Aβ(1–40) and Aβ(1–42), as well as their extension. Moreover, these polyphenols dose-dependently destabilized preformed fAβs. The overall activity of the molecules examined was in the order of: myricetin = morin = quercetin 〉 kaempferol 〉 (+)-catechin = (–)-epicatechin. The effective concentrations (EC50) of myricetin, morin and quercetin for the formation, extension and destabilization of fAβs were in the order of 0.1–1 µm. In cell culture experiments, myricetin-treated fAβ were suggested to be less toxic than intact fAβ, as demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Although the mechanisms by which these polyphenols inhibit fAβ formation from Aβ, and destabilize pre-formed fAβin vitro are still unclear, polyphenols could be a key molecule for the development of preventives and therapeutics for AD.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Helicobacter 8 (2003), S. 0 
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background. Helicobacter pylori CagA is injected into the host cell and tyrosine-phosphorylated. We examined tyrosine-phosphorylation sites of CagA, as well as the function of CagA proteins in vivo and in vitro.Methods. After proteolytic digestion of CagA with lysyl endopeptidase, CagA tyrosine-phosphorylation sites were determined using quadropolar time-of-flight (Q-TOF) mass spectrometry analysis. Specific anti-pY CagA polyclonal and anti-CagA monoclonal antibodies were used to examine gastric mucosal biopsy specimens from H. pylori infected patients.Results. Mass spectrometry identified five crucial tyrosine-phosphorylation sites of CagA at Tyr893, Tyr912, Tyr965, Tyr999, and Tyr1033 within the five repeated EPIYA sequences of H. pylori (NCTC11637)-infected AGS cells. CagA protein also had an immuno-receptor tyrosine-based activation motif (ITAM)-like amino acid sequences in the 3′ region of the cagA, EPIYATIx27EIYATI, which closely resembled the ITAM. CagA proteins: (i) were localized to the 1% TritonX-100 resistant membrane fraction (lipid rafts); (ii) formed a cluster of phosphorylated CagA protein complexes; (iii) associated with tyrosine-phosphorylated GIT1/Cat1 (G protein-coupled receptor kinase-interactor 1/Cool-associated tyrosine-phosphorylated 1), substrate molecules of receptor type protein-tyrosine phosphatase (RPTPζ/β), which is the receptor of VacA; and (iv) were involved in a delay and negative regulation of VacA-induced signal. Furthermore, immunohistochemical staining of gastric mucosal biopsy specimens provided strong evidence that tyrosine-phosphorylated CagA is found together with CagA at the luminal surface of gastric foveola in vivo.Conclusion. These findings suggest an important role for CagA containing ITAM-like sequences in the pathogenesis of H. pylori-related disease.
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