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  • 1
    Electronic Resource
    Electronic Resource
    Linear optical properties of a heavily Mg-doped Al0.09Ga0.91N epitaxial layer (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3188-3190 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The room-temperature absorption coefficient and ordinary refractive index for a ∼0.4-μm-thick p-type wurtzite Al0.09Ga0.91N epitaxial layer were determined via optical transmission measurements. The layer was grown by metal organic chemical vapor deposition and heavily doped (∼5×1019 cm−3) with Mg. Additional measurements of the refractive index by prism coupling to the layer confirmed the transmission results. The low-temperature AlN buffer layer altered the expected interference fringes of the transmission spectrum below the band-gap energy and had to be accounted for in the analysis. The absorption coefficient exhibited band-tail effects and had a reduced slope near band-gap energy as compared to undoped GaN. Using a detailed balance argument, the reduced slope was consistent with the lack of a peak in the continuous-wave photoluminescent emission. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124102
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  • 2
    Electronic Resource
    Electronic Resource
    Ordinary and extraordinary refractive indices for AlxGa1−xN epitaxial layers (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 67-69 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dispersion of the ordinary and extraordinary indices of refraction for wurtzite AlxGa1−xN epitaxial layers with x=0.00, 0.04, 0.08, 0.11, and 0.20 in the range of wavelengths 457〈λ〈980 nm were measured via a prism-coupled waveguide technique. The quantitative accuracy of x is ±10% and the accuracy of the refractive indices is ∼±0.01. The dispersion is found to be well described by a 1st-order Sellmeier dispersion formula. A simple functional form is presented that allows calculation of the refractive indices as functions of x and λ. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124278
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  • 3
    Electronic Resource
    Electronic Resource
    Rab3 Proteins and SNAP-25, Essential Components of the Exocytosis Machinery in Conventional Synapses, are Absent from Ribbon Synapses of the Mouse Retina (1996)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 8 (1996), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: GTP-binding rab proteins, present in synaptic vesicles and endocrine secretory granules, have been shown to be involved in the control of regulated exocytosis. We found rab3 proteins in immunoblots of diverse areas of the mouse central nervous system (spinal cord, olfactory bulb, hippocampus, cerebellum and neocortex). Immunohistochemical observations at light- and electron-microscopical levels in the hippocampus and other areas revealed rab3 proteins in virtually all synaptic fields and terminals of the areas investigated. In the retina, rab3A immunoreactivity was confined to the inner and outer plexiform layers. Ultrastructural examination revealed that rab3A was present in conventional terminals in the inner plexiform layer and in horizontal cell processes of the outer plexiform layer. In contrast ribbon synapses, which play a key role in transferring information from the photoreceptor cells to the central nervous system, were immunonegative. We also tested whether other proteins of the rab3 family are present in ribbon synapses. However, using an antibody recognizing rab3B and rab3C in addition to rab3A, we found no immunoreactivity in these synapses. Interestingly, we observed also no immunoreactivity for synaptosomal-associated protein 25 (SNAP-25) in ribbon synapses, but conventional synapses and horizontal cell processes were heavily stained. Our data show that the known rab3 and SNAP-25 isoforms, which are components of the secretory apparatus of conventional synapses, are absent from ribbon synapses of the retina. Our observations suggest different mechanisms of transmitter exocytosis in conventional and ribbon terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1996.tb01177.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ki-67 and biological behaviour in meningeal haemangiopericytomas (1996)
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Histopathology 29 (1996), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The biological behaviour of meningeal haemangiopericytomas was retrospectively studied using immunohistochemical staining with MIB1, a monoclonal antibody against the Ki-67 antigen, a nuclear protein related to cell proliferation. Paraffin-embedded material from 62 tumours from 40 patients were investigated. The proliferating compartment of the tumours was estimated by evaluating the MIB1 staining index, i.e. the percentage of MIB1 positive nuclei in at least 1000 counted tumour cells in representative areas. The staining index ranged from 1.24% to 39.01%. Statistical analysis revealed no significant correlation between the staining index and recurrence-free survival (χ2 = 0.3922, P = 0.5311). Long-term observation (〉100 months), however, revealed a tendency to longer survival in the group with a staining index less than 5%. According to our results, the MIB1 staining index does not contribute to the accuracy of predicting the clinical outcome of meningeal haemangiopericytomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2559.1996.d01-479.x
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  • 5
    Electronic Resource
    Electronic Resource
    Innere Hirnvenenthrombose bei Colitis ulcerosa und leichtem Schädel-Hirn-Trauma (1999)
    Springer
    Rechtsmedizin 9 (1999), S. 148-151 
    Details
    ISSN: 1434-5196
    Keywords: Key words Internal cerebral vein thrombosis ; Sinovenous thrombosis ; Colitis ulcerosa ; Trauma ; Schlüsselwörter Hirnvenenthrombose ; Sinusthrombose ; Trauma ; Colitis ulcerosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Venöse Abflußstörungen des Gehirns werden mit unterschiedlicher Häufigkeit im Obduktionsgut aufgeführt. Neben entzündlichen Prozessen, hämorheologischen Störungen und Neoplasien kommen bei der forensischen Begutachtung traumatische Ursachen für die Genese von Thrombosen in Frage. Berichtet wird über eine 14 Jahre alt gewordene Schülerin, die 2 1/2 Tage nach einer tätlichen Auseinandersetzung verstarb. Anamnestisch wurde von einer Colitis ulcerosa berichtet. Initial waren weder äußere Verletzungen noch neurologische Auffälligkeiten erkennbar. In der Nacht wurde sie komatös in der Klinik aufgenommen. Die kranielle computertomographische Untersuchung zeigte eine zunehmende intraventrikuläre und intrazerebrale Blutung, Zeichen der venösen Stauung und ein Hirnödem. Die Patientin verstarb im dissoziierten Hirntod. Neuropathologisch fand sich eine in Organisation stehende Thrombose des Sinus sagittalis superior, die sich in die inneren Hirnvenen fortsetzte und die durch die entzündliche Darmerkrankung verursacht war. Eine traumatische Genese war somit auszuschließen.
    Notes: Abstract Thromboses of the cerebral veins which occur at a frequency of 3.75 to 9.3% in autopsy material are caused by local or systemic inflammatory processes, hematological disorders, neoplasms or traumatic brain damage. We report on a 14-year-old girl who suffered from colitis ulcerosa during the last 4 years of life. Immediately after a brawl with a schoolboy she complained of headache and vertigo, but no physical abnormality was detected by the physician. She was admitted to the hospital after becoming comatose during the following night. On neurological examination she was comatous with a decerebrate state, the pupils were small and non-reactive to light, divergent ocular bulbi and bilateral extensor plantar responses. A cerebral computer tomogramm showed a cerebral edema and a hemorrhage in the left basal ganglia and both cerebral ventricles which subsequently increased to the right cerebral ganglia, the corpus callosum and the right cerebral hemisphere. Despite antiedematous therapy the girl died on the second day after the brawl. A neuropathology examination revealed thrombosis of the superior sagittal sinus extending to the internal cerebral veins and a bilateral hemorrhagic infarction of the thalamus and the basal ganglia with intraventricular hemorrhage. As the thrombus in the sagittal sinus showed signs of organisation, a postraumatic origin alone is improbable and a hemorrheological disorder due to colitis ulcerosa seemed to be the main cause.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001940050099
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  • 6
    Electronic Resource
    Electronic Resource
    Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL): a morphological study of a German family (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 341-350 
    Details
    ISSN: 1432-0533
    Keywords: Key words Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) ; Hereditary multi-infarct dementia ; Skin biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized clinically by recurrent cerebral infarcts, subcortical dementia and pseudobulbar palsy, and morphologically by a granular degeneration of cerebral and, to a lesser degree, extracerebral blood vessels. We present morphological findings in a further German family affected by CADASIL. The index case showed the typical periodic acid-Schiff-positive granular degeneration of vascular smooth muscle cells (VSMC) in cerebral vessels, which did not react with antibodies against various immunoglobulins or complement factors. Ultrastructurally, granular osmiophilic material (GOM) covered the VSMC in different cerebral regions as well as in extracerebral organs (muscle, nerve, skin, small and large intestine, liver, kidney and heart). Skin biopsy samples from other family members of the last two generations also revealed GOM irrespective of the clinical symptomatology (CADASIL, migraine only or asymptomatic). Patients in the third generation had higher amounts of GOM in skin vessels than did asymptomatic or migraine patients in the fourth generation. We conclude that skin biopsy is a useful and less-invasive screening method for the differential diagnosis of CADASIL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050528
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  • 7
    Electronic Resource
    Electronic Resource
    Different variants of frontotemporal dementia: a neuropathological and immunohistochemical study (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 170-179 
    Details
    ISSN: 1432-0533
    Keywords: Key words Frontotemporal dementia ; Dementia of ; frontal lobe type ; Pick’s disease ; Motor neuron disease ; with dementia ; Pick bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Histological and immunohistochemical findings in 20 cases of frontotemporal dementias – 8 cases of dementia of frontal lobe type (DFT), 7 cases of Pick’s disease (PD), and 5 cases of motor neuron disease with dementia (MND/D) – are presented. Common features of all three syndromes were: frontotemporal atrophy, involvement of subcortical nuclei, and swollen chromatolytic cells. Ubiquitin (Ub)-positive and tau-negative inclusions in cortical, hippocampal, and motor neurons were found in MND/D and DFT cases, suggesting a common pathogenesis of MND/D and DFT. MND/D showed the same cytoskeletal alterations in motor nuclei as MND without dementia: Bunina bodies and skein-like, Ub-positive inclusions. DFT differed from PD in the preponderance of histopathological changes in upper cortical layers, the sparseness of chromatolytic cells, and the absence of tau-positive Pick bodies (PBs). There were, however, two transitional cases showing Pick-type histology but no PBs, thus linking DFT and PD. PBs expressed chromogranin B and secretoneurin strongly, but chromogranin A only weakly. They were negative for the 70-kDa heat-shock protein, metallothionein, and glutathione-S-transferase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050505
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  • 8
    Electronic Resource
    Electronic Resource
    Die Riesenaxonneuropathie Eine Kasuistik (1996)
    Springer
    Der Pathologe 17 (1996), S. 213-218 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Riesenaxonale Neuropathie ; Mikrofilamentallagerung ; Key words Giant axonal neuropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary We report a sporadic case of giant axonal neuropathy (GAN) starting in a 5-year-old boy with gait disturbance. At the age of 10 years he showed signs of a sensomotoric polyneuropathy and central neurological symptoms: intention tremor, nystagmus and visual disturbance. The boy also had curly hair. Sural nerve biopsy showed many giant axons with accumulation of microfilaments, which were also found in cytoplasma of Schwann cells, endothelial cells and fibrocytes. Similar changes were detected in endothelial cells of a muscle biopsy, which additionally displayed neurogenic atrophy and target fibers. Immunohistochemically, desmin, vimentin, heat shock protein 70, and ubiquitin were not detectable in giant axons, which, however, contained neurofilament protein 68, 200 and β -tubulin. Our case shows that careful ultrastructural examination of a muscle biopsy may point to the diagnosis of GAN.
    Notes: Zusammenfassung Wir berichten über einen sporadischen Fall von Riesenaxonneuropathie (RAN), die bei einem 5 jährigen Jungen mit einer progredienten Gangstörung begann. Auffällig waren außerdem stumpfe, gekräuselte Haare. Im Alter von 10 Jahren bestanden eine sensomotorische Polyneuropathie und zentral-neurologische Symptome: Visusminderung, sakkadierte Blickfolge und Intentionstremor. Die Biopsie des N. suralis bestätigt das Vorliegen einer Neuropathie und zeigt viele Risenaxone mit ultrastruktureller Anhäufung von Mikrofilamenten. Diese sind auch im Zytoplasma der Schwann-Zellen, Endothelzellen und Fibrozyten zu erkennen. Auch intramuskuläre Endothelzellen enthalten gleichartige Veränderungen; darüber hinaus ist im Muskel ein neurogenes Gewebsbild ausgebildet. Immunhistochemisch exprimieren die Axone Neurofilamentprotein 200 und 68 sowie β -Tubulin, jedoch weder Desmin, Vimentin, Heat-shock-Protein 70 oder Ubiquitin. Der Fall illustriert, daß die ultrastrukturelle Untersuchung einer Muskelbiopsie diagnostische Hinweise für eine RAN liefern kann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050158
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