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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: During aging of the human brain, and particularly in Alzheimer's disease, progressive neuronal loss is accompanied by the formation of highly stable intra- and extraneuronal protein fibers. Using fluorescence-activated particle sorting, a method has been developed for purifying essentially to homogeneity the extracellular amyloid fibers that form the cores of senile plaques. The purified plaque cores each contain 60–130 pg of protein. Their amino acid composition shows abundant glycine, trace proline, and ∼50% hydrophobic residues; it resembles that of enriched fractions of the paired helical filaments (PHF) that accumulate intraneuronally in Alzheimer's disease. Senile plaque amyloid fibers share with PHF insolubility in numerous protein denaturants and resistance to proteinases. However, treatment of either fiber preparation with concentrated (88%) formic acid or saturated (6.8 M) guanidine thiocyanate followed by sodium dodecyl sulfate causes disappearance of the fibers and releases proteins migrating at 5–7.000 and 11–15.000 Mr which appear to be dimerically related. Following their separation by size-exclusion HPLC, the proteins solubilized from plaque amyloid and PHF-enriched fractions have highly similar compositions and, on dialysis, readily aggregate into higher Mr polymers. Antibodies raised to the major low-Mr protein selectively label both plaque cores and vascular amyloid deposits in Alzheimer brain but do not stain neurofibrillary tangles, senile plaque neurites, or any other neuronal structure. Thus, extraneuronal amyloid plaque filaments in Alzheimer's disease are composed of hydrophobic low-Mr protein(s) which are also present in vascular amyloid deposits. Current evidence suggests that such protein(s) found in PHF-enriched fractions may derive from copurifying amyloid filament srather than from PHF.
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The proteins of membrane and cytosol fractions from frozen human postmortem brain were analyzed by two-dimensional gel electrophoresis (isoelectric range: 5.1–6.0) and both Coomassie-blue and ammoniacal silver staining. Cytosol preparations were analyzed from six different postmortem brains from patients with various neurologic diagnoses and immediate causes of death. Intervals between death and brain freezing (−70oC) ranged from 2 to 20 h. The vast majority of proteins detected in these cytosol fractions had identical molecular weights and isoelectric points in each of six human brains examined. However, in some tissue samples tubulin was either quantitatively decreased or undetectable. The possibility that this partial or complete depletion of tubulin was related to postmortem interval and/or brain freezing was studied using rat forebrain tissue. Rat brain incubated at room temperature for up to 24 h did not reproduce the changes seen in the region of human cytosol tubulin. However, other changes seen in the two-dimensional electrophoretic pattern of rat cytosol proteins did relate to postmortem interval, brain freezing, or both. Rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum were prepared from three human brains, with highly reproducible two-dimensional patterns. Protein analysis of these membrane fractions revealed that human RER contained significant amounts of tubulin, in contrast to rat RER which contained no detectable tubulin. This discrepancy was elucidated by allowing rat brains to remain at room temperature for 24 h before freezing; gels of rat RER prepared from this tissue showed that tubulin subunits were present.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 38 (1982), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Postsynaptic density (PSD) preparations isolated from canine cerebral cortex that had been left at 0–37°C for various times were found to become enriched in two bands in a time- but not temperature-dependent manner. The two bands were identified as tubulin subunits by gel mobility and immunology. Of all the isolated synaptic structures the increase in tubulin occurred primarily in the PSD fraction. The increase of tubulin also occurred in PSD preparations isolated from canine cerebellum and rat forebrain. Results obtained when PSD fractions were isolated from canine brain obtained as rapidly as possible after the death of the animal indicate that the maximum amount of tubulin in the PSD preparations is 2.5% of total Coomassie blue-stained protein as determined by scanning of gel electrophoretograms. These results imply that tubulin is probably not a major structural protein of the PSD as it exists in situ.
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  • 5
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The binding of l,3-[3H]-dipropyl-8-cyclopentylxanthine ([3H]-DPCPX), a specific adenosine Ai receptor antagonist, was examined in rat vas deferens membrane preparations using radioligand binding techniques.2. l,3-[3H]-Dipropyl-8-cyclopentylxanthine bound to these preparations with a KD of 1.07 ± 0.14 nmol/L (n = 6). The density of [3H]-DPCPX binding sites was 133.38 ± 5.57 fmol/mg protein.3. Computer analysis indicated that nucleosides competed for [3H]-DPCPX binding at two distinct sites. The rank order of potency at the higher affinity site corresponded to R-phenyliso-propyladenosine (R-PIA) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 2-chloroadenosine (2-CI ADO) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 cyclopentyladenosine (CPA) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 N-ethylcarboxamidoadenosine (NECA)〉s-phenylisopropyladenosine (s-PIA). Kj values were in the low nmol/L range. The rank order of nucleoside potency at the lower affinity site corresponded to R-PIA 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 CPA 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉NECA〉=2-ClADO〉 S-PIA. Ki values were in the low μmol/L range.4. Nucleotides competed for [3H]-DPCPX binding at a single site only. The rank order of potency at this site corresponded to a,β-methylene ATP 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉βγ-methylene ATP 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉= ATP. Ki values were in the high |xmol/L range. This site seemed to correspond with one of the two binding sites predicted by nucleoside competition binding.5. The ATP-regenerating compound myokinase did not significantly change the competition curve for ATP, indicating that the competition for [3H]-DPCPX binding observed in the presence of ATP was due to an effect of ATP per se and not to an action of a degradation product.6. The results demonstrate that in rat vasa deferentia there exist two distinct binding sites for [3H]-DPCPX. One of these sites binds only nucleosides and may represent an adenosine Ai receptor, as usually defined. The other site binds both nucleosides and nucleotides and may represent an atypical adenosine A1 receptor, an atypical P2 or a P3 purinoceptor.
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  • 6
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously shown that human metallopanstimulin (MPS-1) is a ubiquitous 9.4-kDa multifunctional ribosomal S27/nuclear “zinc finger” protein which is expressed at high levels in a wide variety of cultured proliferating cells and tumor tissues, including melanoma. In the present study, we have examined the expression of the MPS-1 protein in various types of human benign and malignant melanocytic lesions of the skin. The expression of the MPS-1 protein was studied by immunohistochemistry using specific anti-MPS-1 antibodies. We found that in benign nevi, the staining is weak and in a gradient; most often, only type A melanocytes stain positive. The B and particularly the C types are negative. Remarkably, congenital nevi show a similar gradient staining of regular benign nevi, but in addition one example showed intensely positive dermal nodules adjacent to areas of negative melanocytes. In melanomas, the staining patterns for MPS-1 are more complex. While some melanomas stain evenly and intensely positive, others have remarkably variable expression of MPS-1. The scattered melanocytes migrating to the upper layers of the epidermis are usually intensely positive. In summary, benign lesions stain in an orderly pattern with staining gradients that correlate with the cellular differentiation of the nevi. Malignant melanomas have an erratic, often intense staining that also correlates with the disorderly growth of these neoplasms. These differential results indicate that the MPS-1 antigen is a useful marker for melanocytic lesions at the immunohistochemical level.
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  • 7
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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