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  • 1
    Electronic Resource
    Electronic Resource
    Immunoreactivity of CD45, a protein phosphotyrosine phosphatase, in Alzheimer's disease (1991)
    Springer
    Acta neuropathologica 83 (1991), S. 12-20 
    Details
    ISSN: 1432-0533
    Keywords: CD45 ; Protein phosphotyrosine phosphatase ; Microglia ; Intracellular signaling ; Alzheimer's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Both protein kinases and phosphoprotein phosphatases are important components of signal transduction systems in cells. Recent studies in Alzheimer's disease (AD) have shown abnormal protein phosphorylation in the cortex suggesting an alteration in these enzymes. In the present study, an antibody against CD45 was used to analyze the status of this protein phosphotyrosine phosphatase in AD. We studied and quantified the immunohistochemical and immunochemical distribution of this integral membrane protein in control and AD brain. We found that anti-CD45 immunostained the great majority of microglia, both resting and activated. These cells were Ricinus communis agglutinin I positive and glial fibrillary acidic protein and neurofilament negative. The AD frontal cortex showed a 35% (P〈0.01) increase in the number of anti-CD45 immunoreactive microglia as compared with controls. These results were consistent with the immunoblot quantification of CD45 immunoreactivity following native gel electrophoresis. In AD, 30% of the CD45-immunostained microglia were clustered in the neuritic plaques (about six per plaque) while the remaining 70% were scattered in the neuropil. The AD hippocampus showed an increase in CD45-immunoreactive microglia in the molecular layer of the dentte gyrus. At the ultrastructural level, CD45 immunoreactivity was localized exclusively to the plasma membrane of the microglia. The presence of the anti-CD45 immunoreactivity in microglia suggests the possibility that they may require the presence of CD45 as a cell surface receptor which may regulate cell function through modulation of intracellular signaling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294425
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  • 2
    Electronic Resource
    Electronic Resource
    Membranous lipodystrophy (Nasu-Hakola disease) with thalamic degeneration: report of an autopsied case (1991)
    Springer
    Acta neuropathologica 82 (1991), S. 414-419 
    Details
    ISSN: 1432-0533
    Keywords: Membranous lipodystrophy ; Thalamic degeneration ; Neuropathology ; Autopsy ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An autopsied case of membranous lipodystrophy (Nasu-Hakola disease, NHD) with thalamic degeneration was reported. A 34-year-old Japanese man was diagnosed as having NHD by bone biopsy prior to the onset of clinical symptoms. His maternal grandfather and paternal grandmother are cousins, but this family history is negative for NHD. He developed frontal lobe syndrome at the age of 35 with progressive dementia, and died of acute renal failure at the age of 46. Gross inspection of the brain detected atrophy and softening of the cerebral white matter, predominantly in the frontal lobe. Microscopically, numerous spheroids, predominant fibrillary gliosis with less prominent demyelination “dissociation glio-myélinique” and scanty sudanophilic lipid droplets were observed, indicating the sclerosing type of NHD. An unusual pathological finding in this case was selective involvement of the thalamic nuclei with preservation of the other gray matter except for focal cortical necrosis. The topography of the affected thalamic nuclei is similar to that of systemic thalamus degeneration. An association with thalamic degeneration in NHD has not been previously reported. The present case suggests that NHD also affects the thalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296554
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  • 3
    Electronic Resource
    Electronic Resource
    Altered Protein Tyrosine Phosphorylation in Alzheimer's Disease (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The activity of protein tyrosine kinases was determined in extracts from Alzheimer's disease brains and age-and postmortem time-matched control brains at autopsy using the synthetic peptide substrate poly(Glu4Tyr1). The specific activity of protein tyrosine kinases in the particulate fraction decreased roughly twofold (p 〈 0.02) in Alzheimer's disease frontal cortex relative to unaffected control cortex. Cytosolic protein tyrosine kinase activity in Alzheimer's disease tissue was not significantly different from that in control tissue. In contrast to reduced particulate protein tyrosine kinase activity, analysis of Western blots of cytosolic and particulate fractions revealed increases in cytosolic antiphosphotyrosine immunoreactive polypeptides with molecular masses of 55 and 60 kDa. Quantitative immunohistochemistry and morphometry of frontal cortex sections with the antiphosphotyrosine antibody indicated increased antiphosphotyrosine staining in the neurons, although the number of antiphosphotyrosine-positive neurons per square millimeter decreased. Also, increased antiphosphotyrosine staining was observed in the hippocampal neurons. These results suggest that altered protein tyrosine kinases and protein tyrosine phosphorylation are involved in the pathology of Alzheimer's disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb11405.x
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in the Activity of Protein Kinase C and the Differential Subcellular Redistribution of Its Isozymes in the Rat Striatum During and Following Transient Forebrain Ischemia (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The changes in the levels of protein kinase C [PKC(α, βII, γ)] were studied in cytosolic and particulate fractions of striatal homogenates from rats subjected to 15 min of cerebral ischemia induced by bilateral occlusion of the common carotid arteries and following 1 h, 6 h, and 48 h of reperfusion. During ischemia the levels of PKC(βII) and -(γ) increased in the particulate fraction to 390% and 590% of control levels, respectively, concomitant with a decrease in the cytosolic fraction to 36% and 20% of control, respectively, suggesting that PKC is redistributed from the cytosol to cell membranes. During reperfusion the PKC(βII) levels in the particulate fraction remained elevated at 1 h postischemia and decreased to below control levels after 48 h reperfusion, whereas PKC(γ) rapidly decreased to subnormal levels. In the cytosol PKC(βII) and -(γ) decreased to 25% and 15% of control levels at 48 h, respectively. The distribution of PKC(α) did not change significantly during ischemia and early reperfusion. The PKC activity in the particulate fraction measured in vitro by histone IIIS phosphorylation in the presence of calcium, 4β-phorbol 13-myristate 12-acetate, and phosphatidylserine (PS) significantly decreased by 52% during ischemia, and remained depressed over the 48-h reperfusion period. In the cytosolic fraction PKC activity was unchanged at the end of ischemia, and decreased by 47% after 6 h of reperfusion. The appearance of a stable cytosolic 50-kDa PKC-immunoreactive peptide or an increase in the calcium-and PS-independent histone IIIS phosphorylation was not observed. Consequently, during ischemia PKC, preferentially PKC(γ) and PKC(βII), is translocated from the cytosol and inserted into cell membranes, concomitant with a decrease in PKC activity. In the reperfusion phase the depression of PKC activity persists and the enzyme is degraded. The observed translocation and downregulation of PKC during ischemia and reperfusion may be of significance for the development of ischemic neuronal damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb11415.x
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  • 5
    Electronic Resource
    Electronic Resource
    Secreted Form of Amyloid β/A4 Protein Precursor (APP) Binds to Two Distinct APP Binding Sites on Rat B103 Neuron-Like Cells Through Two Different Domains, but Only One Site Is Involved in Neuritotropic Activity (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Recent studies have identified the Alzheimer's disease amyloid β/A4 protein precursor (APP) as a trophic and/or tropic protein on several types of cells, including fibroblasts, primary culture neurons, PC12 cells, and B103 neuron-like cells. Many trophic proteins bind heparin, and it is believed that the heparin-binding domain is crucial for the trophic activity of these proteins. APP also binds heparin. The current studies were undertaken to examine the hypothesis that the neuritotropic activity of APP requires heparin binding. It was found that APP produced in E. coli bound B103 cells through detergent-extractable molecules. Approximately 50% of the binding sites were heparinase-sensitive, and heparin and heparan sulfate competed for APP binding to these sites. The heparinase-insensitive sites were recognized by a stretch of 17 amino acids of APP (residues 319–335) that contains the neuritotropic activity of APP. A mutant APP with a deletion at this site was capable of binding to the heparinase-sensitive sites, although this molecule was not neuritotropic to B103 neuron-like cells. Therefore, the neuritotropic site and the heparin-binding site are distinct in APP, and the neuritotropic effect of APP is produced through its binding to detergent-extractable and heparinase-insensitive sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63020495.x
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  • 6
    Electronic Resource
    Electronic Resource
    In situ observations of As atoms at step sites of vicinal Si(100) surfaces by coaxial impact-collision ion scattering spectroscopy (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1592-1597 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ observations of As atoms at step sites of vicinal Si (100) surfaces have been performed by coaxial impact-collision ion scattering spectroscopy. It is found that some As atoms remain at Si step sites even at a high substrate temperature of 780 °C under an As residual pressure, in spite of evaporation of As atoms from terrace sites. This result indicates that As atoms at step sites are energetically more stable than the As dimers on the terrace. Moreover, the angular profiles of the scattering intensity from As atoms at step sites suggest that there is atomic displacement of As atoms towards the Si substrate at the step sites. An atomic model of the As/Si system is proposed from the results of computer simulation for the scattering intensity profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357738
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  • 7
    Electronic Resource
    Electronic Resource
    Growth and characterization of GaSe and GaAs/GaSe on As-passivated Si(111) substrates (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7211-7222 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown and characterized epitaxial layered structure GaSe on As-passivated Si(111) and GaAs on GaSe on As-passivated Si(111) for the ultimate purpose of using the layered structure GaSe as a lattice mismatch/thermal expansion mismatch buffer layer in the GaAs on Si system. Films were grown on nominally (111) oriented Si substrates by molecular beam epitaxy and characterized by in situ reflection high energy electron diffraction, as well as by ex situ scanning electron microscopy and both plan-view and cross-sectional TEM (transmission electron microscopy). In this study, GaSe was grown epitaxially on As-passivated Si(111) substrates at 500 °C with Se/Ga BEP (beam equivalent pressure) ratios of ∼10 and ∼20. Small droplets were observed on the surface after GaSe growth. These are thought to be droplets of unreacted Ga. The density and size of the droplets decreases with the increasing Se/Ga BEP ratio. When the GaSe surface is exposed to As, the droplets become GaAs islands. Subsequent GaAs growth was carried out at 400 and 500 °C, giving the following results for 300-A(ring)-thick films: as grown GaAs films were highly twinned, and some polycrystalline GaAs was present in the film grown at 400 °C. In situ annealing at 650 °C for 10 min reduced the density of twins in both cases. In plan-view TEM, Moiré fringes from both GaAs and GaSe are observed and show conclusively that the GaAs grew epitaxially on the GaSe without contacting the Si substrate. Cross-sectional TEM shows the interface between the Si and GaSe is not smooth on the atomic scale. In spite of this, the GaSe becomes smooth with about 2 monolayers of growth and the GaAs/GaSe interface appears to be very smooth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355038
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  • 8
    Electronic Resource
    Electronic Resource
    In situ observation of the initial growth stages in GaAs/InAs by coaxial impact collision ion scattering spectroscopy: Transition from two-dimensional-like to three-dimensional island growth (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3802-3805 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial growth stages of the highly lattice-mismatched GaAs/InAs system was studied by coaxial impact collision ion scattering spectroscopy (CAICISS). The GaAs coverage on the InAs substrate during GaAs molecular beam epitaxial growth was monitored in situ by low incident angle CAICISS. The scattering intensity as a function of the deposited amount of GaAs can be divided into three characteristic regions. First, the scattering intensity from In decreases proportionally with the amount of deposited GaAs molecules. However, the intensity decrease stops abruptly before the surface is completely covered with a GaAs layer, and remains constant. Then, the intensity gradually decreases. This result shows that there exist three kinds of growth stages in the process of GaAs deposition on an InAs substrate. The mechanism of the growth mode transition, corresponding to the three kinds of growth stages is discussed from the viewpoint of a strain energy change on the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350893
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  • 9
    Electronic Resource
    Electronic Resource
    Real-time investigations of GaAs surface cleaning with a hydrogen electron cyclotron resonance plasma by optical reflection spectroscopy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3117-3119 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The composition changes during GaAs oxide removal and the subsequent cleaning with a hydrogen electron cyclotron resonance plasma have been investigated with real-time optical reflection spectroscopy. It is found that the oxide is not completely removed at low temperatures, resulting in a thick damaged surface region. At moderate temperatures (300–500 °C) the plasma exposure is characterized by a two-step process: a removal of the native oxide in a few seconds followed by a gentle etch of the GaAs. In the latter step the plasma exposure leads to a surface region with little damage to the crystal. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112454
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  • 10
    Electronic Resource
    Electronic Resource
    In situ monitoring of electron cyclotron resonance plasma processing of GaAs surfaces by optical reflection spectroscopy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2661-2663 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ reflection spectroscopy is demonstrated to be a useful technique for monitoring the damage to the surface of GaAs substrates induced by ions from an electron cyclotron plasma. Distinct differences in the reflectance spectra of GaAs substrates are observed between etching by argon ions and chemical cleaning by hydrogen ions. For argon it is found that the damage layer thickness increases linearly with the argon ion energy. Hydrogen ions induce a damage layer of 3.1 nm and arsenic atoms are preferentially removed from the surface as the ion energy increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111484
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