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  • Electron microscopy  (2)
  • Glioma  (2)
  • Synaptology  (2)
  • sulfated zirconia  (2)
  • 1
    ISSN: 1572-879X
    Keywords: oxidative dehydrogenation ; ethane ; sulfated zirconia ; lithium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidative dehydrogenation of ethane over sulfated-zirconia-supported lithium chloride catalysts has been systematically investigated. The optimal experimental parameters were obtained. It is found that sulfation of zirconia increases the catalytic activity. 2–3.5 wt% lithium chloride on sulfated zirconia catalysts exhibit high catalytic activity for oxidative dehydrogenation of ethane, with particularly high activity for ethene production. 70% selectivity to ethene at 98% ethane conversion, giving 68% ethene yield, is achieved over 3.5 wt% LiCl/SZ at 650°C.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-879X
    Keywords: sulfated zirconia ; lithium chloride ; metal oxides ; ethane ; oxidative dehydrogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of some transition‐ and lanthanide‐metal oxides in LiCl/sulfated‐zirconia (SZ) catalysts on catalytic behavior in the oxidative dehydrogenation of ethane were investigated. It is found that modification of LiCl/SZ by metal oxides significantly improves the catalytic activity and ethene yield. Among those additives, Ni and Nd oxides show the best promoting effect in terms of ethane conversion and ethene yield. 93% ethane conversion with 83% selectivity to ethene has been achieved over the Nd2O3–LiCl/SZ catalyst at 650°C. In addition, those oxide‐promoted LiCl/SZ catalysts are also found to exhibit a longer stability in catalytic performance. Metal‐oxide additives change the chemical structure and surface redox properties, which accounts for the enhancement of activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 196 (1997), S. 465-476 
    ISSN: 1432-0568
    Keywords: Key words Pharyngeal motoneuron ; Cytoarchitecture ; Retrograde tracing study ; Swallowing ; Synaptology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We investigated the fine structure of the semicompact formation of the nucleus ambiguus (AmS), which was identified by retrogradely labeled pharyngeal (PH) motoneurons. When cholera toxin subunit B-conjugated horseradish peroxidase was injected into the lower pharyngeal muscle, many retrogradely labeled PH neurons were found throughout the AmS. Besides the PH neurons, two types of neurons were recognized in the AmS: unlabeled medium-sized neurons and unlabeled small neurons. The PH neuron was large (27.6 × 44.1 μm) and polygonal, and contained many Nissl bodies and well-developed cell organelles with a prominent spherical nucleus. The medium-sized neuron was dark and oval (19.3 × 33.2 μm), and contained many free ribosomes and much swollen rough endoplasmic reticulum with a distorted oval nucleus. The small neuron was spindle-shaped (12.3 × 20.2 μm), and had poorly developed cell organelles with an irregularly shaped nucleus. The average number of axosomatic terminals in a sectional plane was largest in the PH neurons (32.8), smaller in the medium-sized neurons (23.1), and smallest in the small neurons (6.3). The number of axo-somatic terminals containing round vesicles (Gray’s type I) was almost equal to that of terminals containing pleomorphic vesicles (Gray’s type II) in the PH neuron, and slightly smaller in the small and the medium-sized neurons. About 60% of the axodendritic terminals were Gray’s type I, and 40% were type II. These results indicate that there are two different types of interneurons besides the PH motoneurons in the AmS.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 177 (1988), S. 485-493 
    ISSN: 1432-0568
    Keywords: Ventral tegmental nucleus of Gudden ; Dorsal tegmental nucleus of Gudden ; Quantitative morphometric study ; Synaptic organization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of neuronal somata and axosomatic synapses in each subnucleus of Gudden's tegmental nuclei was studied by use of electron microscopy. The pars principalis of the ventral tegmental nucleus of Gudden (TVP) is composed of oblong or triangular, medium sized neurons (11.8x22.6 μm, 211.4 μm2) containing many mitochondria, lysosomes, Golgi apparatus, and rough endoplasmic reticulum composing Nissl bodies. The light oval nucleus with a prominent nucleolus is centrally situated, and indentations of its nuclear envelope are recognized in all neurons. The neuron in the pars ventralis of the dorsal tegmental nucleus of Gudden (TDV) is similar to that in the TVP, but its average size is significantly smaller (10.0x18.8 μm, 151.4 μm2), and its organelles are also less well developed. The pars dorsalis of the dorsal tegmental nucleus of Gudden (TDD) is composed of spindle shaped, small neurons (6.9x16.2 μm, 85.1 μm2) characterized by their irregular shaped nucleus with its invaginated envelope. These neurons have a thin rim of cytoplasm, poorly developed organelles and no Nissl bodies. The average number of axosomatic terminals in a sectional plane is 9.9 in the TVP, 9.6 in the TDV and 2.6 in the TDD, and the bouton covering ratio is 24.3% in the TVP, 26.5% in the TDV and 7.4% in the TDD. The respective percentages of round, flat and pleomorphic type axosomatic terminals were estimated, and the flat type terminals were found to be dominant in the TVP, the pleomorphic type terminals in the TDV, and the round type terminals in the TDD.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0533
    Keywords: Glioma ; Tenascin ; Fibronectin ; Cell differentiation ; Tumor angiogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The immunohistochemical distribution of tenascin (TN), fibronectin (FN), and laminin (LN) was investigated in 56 human gliomas (8 astrocytomas, 15 anaplastic astrocytomas, and 33 glioblastomas) with regards to the histological degree of malignancy and the degree of tumor cell differentiation evaluated by the staining of glial fibrillary acidic protein (GFAP). In 8 anaplastic astrocytomas and 28 glioblastomas, TN was predominantly immunolocalized in the basement membrane zone of the proliferating tumor vessels; sections of all astrocytomas were negative for TN staining. FN was localized in the basement membrane zone of the vessels in all astrocytomas, 12 anaplastic astrocytomas, and 22 glioblastomas. In 7 anaplastic astrocytomas and 19 glioblastomas, both TN and FN were expressed to various degrees in the tumor vessels. However, most of the TN-positive vessels did not express FN, and most of the FN-positive vessels were negative for TN staining. Furthermore, in 6 anaplastic astrocytomas and 12 glioblastomas, either TN of FN, but not both, were expressed in any area on serial sections. Most of the tumor cells around TN-positive, FN-negative tumor vessels did not express GFAP. On the other hand, GFAP was present in most tumor cells around TN-negative, FN-positive vessels. LN was detected in all vascular and pial-glial basement membrane zone of the tissues examined. These findings indicate that the degree of histological malignancy and the degree of cell dedifferentiation of human gliomas correlate well with the expression of TN, but are inversely correlated with the expression of FN. We postulate that the expression of TN, but not of FN, plays a role in the promotion of angiogenesis in malignant gliomas.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 68 (1985), S. 87-92 
    ISSN: 1432-0533
    Keywords: Pituitary neoplasm ; Anterior pituitary hormone ; Amyloid ; Electron microscopy ; Bromocriptine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The accumulation of amyloid in pituitary adenomas was examined in relation to the types of adenoma and the effect of bromocriptine treatment. Amyloid had accumulated in 34 of 48 adenomas (71%). The occurrence in prolactin-secreting adenomas and growth hormone-secreting adenomas was 79%, respectively, while that in non-functioning adenomas was 50%. Treatment with bromocriptine enhanced the occurrence and extent of the amyloid accumulation in prolactin- or growth hormone-secreting adenomas. Electron microscopy revealed the initial appearance of the amyloid fibrils in the smooth endoplasmic reticulum and a possible sequential process of their release from the cells. The presence of secretory granules in vesicles containing amyloid fibrils and their simultaneous release with amyloid fibrils suggested that degradation of secretory granules was involved in the formation of amyloid.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0568
    Keywords: Key words Ultrastructure ; Cricothyroid motoneurons ; Posterior cricoarytenoid motoneurons ; Synaptology ; HRP tracing study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The cricothyroid (CT) and the posterior cricoarytenoid (PCA) muscles in the larynx are activated by the laryngeal motoneurons located within the nucleus ambiguus; these motoneurons receive the laryngeal sensory information from the nucleus tractus solitarii (NTS) during respiration and swallowing. We investigated whether the neurons in the NTS projected directly to the laryngeal motoneurons, and what is the synaptic organization of their nerve terminals on the laryngeal motoneurons using the electron microscope. When wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the NTS after cholera toxin subunit B-conjugated HRP (CT-HRP) was injected into the CT muscle or the PCA muscle, the anterogradely WGA-HRP-labeled terminals from the NTS were found to directly contact the retrogradely CT-HRP-labeled dendrites and soma of both the CT and the PCA motoneurons. The labeled NTS terminals comprised about 4% of the axosomatic terminals in a section through the CT motoneurons, and about 9% on both the small (PCA-A) and the large (PCA-B) PCA motoneurons. The number of labeled axosomatic terminals containing round vesicles and making asymmetric synaptic contacts (Gray’s type I) was almost equal to that of the labeled terminals containing pleomorphic vesicles and making symmetric synaptic contacts (Gray’s type II) on the CT motoneurons. The labeled axosomatic terminals were mostly Gray’s type II on the PCA-A motoneurons, while the majority of them were Gray’s type I on the PCA-B motoneurons. These results indicate that the laryngeal CT and PCA motoneurons receive a few direct excitatory and inhibitory inputs from the neurons in the NTS.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 126 (1994), S. 84-92 
    ISSN: 0942-0940
    Keywords: Glioma ; astrocytoma ; glioblastoma ; leptomeningeal dissemination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To understand the clinicopathology features of leptomeningeal dissemination of malignant gliomas, a total of 157 consecutive patients treated between 1978 and 1989 were analysed. Twenty-two patients (14%) were judged to have dissemination. In 20 patients, the dissemination was diagnosed antemortem. Eleven patients had neurological deficits due to dissemination, whereas the other 9 without these had CT or myelographic evidence of dissemination. The peak incidence of dessemination was seen in the first and second decades of life. The mean age of 22 patients with dissemination was 31 years, significantly lower than that (44.5 years) of patients without dissemination. Fifteen patients developed dissemination within one year after diagnosis (early dissemination), 60% of them were less than 30 years of age. All patients with late dissemination (more than one year after diagnosis) underwent a second craniotomy for tumour removal before dissemination, while none of the 15 patients with early dissemination did. Survival after diagnosis in patients with dissemination was shorter, although statistically not significant, than that of patients without dissemination. Survival after dissemination was limited in all patients (mean 19 weeks, range 2–39 weeks). Immunohistochemical study revealed that the disseminated tumour expressed less glial fibrillary acidic protein than the primary tumour. Our results suggest that dissemination does not seem to result from extended survival of the patients, but may occur at any time in malignant gliomas. Some malignant gliomas, especially in younger patients, have a capability to acquire biological characteristics suitable for dissemination in the earlier stage of the disease.
    Type of Medium: Electronic Resource
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