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  • 1
    Electronic Resource
    Electronic Resource
    Optical-field calculations for lossy multiple-layer AlxGa1−xN/InxGa1−xN laser diodes (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1196-1203 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical-field profiles in wide-band-gap AlxGa1−xN/InxGa1−xN multiple-quantum well (MQW) separate-confinement heterostructure (SCH) laser diodes (LDs) were calculated using a 2×2 transfer-matrix approach that accommodates complex refractive indices. The refractive indices of AlxGa1−xN and InxGa1−xN were approximated by shifting the refractive index of GaN according to the band-gap energy of the solid solution. Current LDs were analyzed and show reasonable optical confinement. Optimization of the SCH waveguide for a three MQW active region was performed by varying the waveguide and cladding layer thicknesses. For 0.8μm thick Al0.10Ga0.90N cladding layers, waveguides on sapphire and SiC substrates had a maximum confinement factor of ∼3.3%. Layers outside of the waveguide strongly affected the optical field for thin (∼0.4 μm) cladding layer thicknesses and resulted in resonant coupling of the light out of the waveguide. Sapphire substrates were found to enhance light confinement, while SiC substrates were found to reduce optical confinement as the cladding layer thickness is reduced. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368185
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  • 2
    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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  • 3
    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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  • 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
    Colloid cysts of the third ventricle: an immunohistochemical study (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Histopathology 21 (1992), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Eleven colloid cysts of the third ventricle were investigated by immunohistochemistry using 16 mono- and polyclonal antibodies. Colloid cyst epithelium, choroid plexus epithelium and ependyma showed different immunohistochemical profiles. In particular, antibodies to different cytokeratins and to transthyretin revealed considerable and constant differences of immunoreactivity. Therefore, common derivation of the three tissues seems unlikely. Our findings are interpreted in favour of the non-neuroepithelial origin of third ventricular colloid cysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2559.1992.tb00340.x
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  • 6
    Electronic Resource
    Electronic Resource
    Differential Expression of Synaptophysin and Synaptoporin During Pre- and Postnatal Development of the Rat Hippocampal Network (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The closely related synaptic vesicle membrane proteins synaptophysin and synaptoporin are abundant in the hippocampal formation of the adult rat. But the prenatal hippocampal formation contains only synaptophysin, which is first detected at embryonic day 17 (E17) in perikarya and axons of the pyramidal neurons. At E21 synaptophysin immunoreactivity extends into the apical dendrites of these cells and in newly formed terminals contacting these dendrites. The transient presence of synaptophysin in axons and dendrites suggests a functional involvement of synaptophysin in fibre outgrowth of developing pyramidal neurons. Synaptoporin expression parallels the formation of dentate granule cell synaptic contacts with pyramidal neurons: the amount of hippocampal synaptoporin, determined in immunoblots and by synaptoporin immunostaining of developing mossy fibre terminals, increases during the first postnatal week. Moreover, in the adult, synaptoporin is found exclusively in the mossy fibre terminals present in the hilar region of the dentate gyrus and the regio inferior of the cornu ammonis. In contrast, synaptophysin is present in all synaptic fields of the hippocampal formation, including the mossy fibre terminals, where it colocalizes with synaptoporin in the same boutons. Our data indicate that granule neuron terminals differ from all other terminals of the hippocampal formation by the presence of both synaptoporin and synaptophysin. This difference, observed in the earliest synaptic contacts in the postnatal hippocampus and persisting into adult life, suggests distinct functions of synaptoporin in these nerve terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1994.tb00569.x
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  • 7
    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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  • 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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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Infantile multiple system atrophy with cytoplasmic and intranuclear glioneuronal inclusions (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 642-647 
    Details
    ISSN: 1432-0533
    Keywords: KeyWordsInfantile multiple system atrophy Ubiquitin ; Neuronal intranuclear hyaline inclusion disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report presents a case of infantile multiple system atrophy with probably autosomal recessive inheritance. The female patient developed generalized muscular hypotonia, myoclonias and tonic-clonic seizures at the age of 8 months, followed by gradual development of choreoathetotic hyperkinesia and increasing psychomotor retardation. Metabolic disease was ruled out and the child died of aspiration pneumonia at the age of 5 years. General autopsy was unremarkable, but neuropathological examination showed degeneration of cerebellum, inferior olives, medial thalamus, Clarke's nucleus, anterior horn cells, corticospinal, spinocerebellar tracts, and posterior columns. Immunohistochemically many neurons contained intranuclear and intracytoplasmic ubiquitin-positive inclusions, which did not contain neurofilament or tau epitopes and ultrastructurally consisted of granulofilamentous material. We tentatively classify this case as a form of infantile multiple system atrophy linked to neuronal intranuclear hyaline inclusion disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293326
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