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  • 2000-2004  (21)
  • 1910-1914
  • 1890-1899
  • Electron microscopy
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 436 (2000), S. 560-566 
    ISSN: 1432-2307
    Schlagwort(e): Key words M cell ; HRP ; Nasopharyngeal lymphoid tissue ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The nasopharyngeal tonsils (adenoids) are prominent components of human nasal-associated lymphoid tissues (NALT). However, the role of the nasopharyngeal tonsils in antigen uptake for initiation of the mucosal immune response is unknown. The aims of this study were to describe the ultrastructure and function of the M cells of the human nasopharyngeal tonsils and to clarify their capacity for antigen uptake. Tissues obtained from eight patients undergoing adenectomy were examined by light and electron microscopy. Lymphoepithelium covers the nasopharyngeal lymphoid tissue and consists of ciliary epithelium, non-ciliary epithelial cells, M cells, goblet cells, and many intraepithelial lymphoid cells. M cells have irregular and broad cytoplasm-containing microvilli on their surface and small vesicles in their cytoplasm. Many lymphoid cells were enfolded by M cells. The uptake of horseradish peroxidase (HRP) in the tissue in organ culture was studied using histochemical techniques. Excised adenoid tissue was incubated in RPMI 1640 culture media with HRP for 10, 30, and 60 min. HRP which had adhered to the surface was taken up in vesicles and then transported in vesicles and tubules by M cells. The M cells of nasopharyngeal lymphoid tissue were ultrastructurally and functionally similar to those in human Peyer’s patches and colonic lymphoid follicles. These findings indicate that NALT bears similarities to the gut-associated lymphoid tissue, and its antigen uptake capacity may be important for initiation of immunity in the upper aerodigestive tract.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 436 (2000), S. 628-633 
    ISSN: 1432-2307
    Schlagwort(e): Key words Prostate adenocarcinoma ; Endocrine cells ; Immunohistochemistry ; FSH ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We report an unusual variant of prostatic adenocarcinoma with marked endocrine differentiation (mixed endocrine-exocrine adenocarcinoma). Endocrine cells accounted for 60% of the tumour cells, were positive with silver impregnation and for chromogranin A, synaptophysin, and neuron-specific enolase, and coexpressed the exocrine antigens prostatic acid phosphatase and prostatic-specific antigen. Most of the endocrine cells were basophilic with haematoxylin-eosin and proved immunoreactive for alpha subunit of human chorionic gonadotropin and follicle-stimulating hormone. The remaining endocrine cells were represented by eosinophilic cells positive for serotonin, and by calcitonin and serotonin-immunoreactive cells not identifiable in haematoxylin-eosin-stained sections. On ultrastructural analysis, two types of endocrine cells were identified. The most frequent cell type showed abundant cytoplasmic round, electron-dense neurosecretory granules, either small (212±44 nm) or large (471±114 nm), resembling those of gonadotropic pituitary cells. The second type of endocrine cells contained irregular electron-dense granules similar to those of serotonin-storing enterochromaffin cells.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2161
    Schlagwort(e): Keywords Ectopic calcification ; Deep posterior compartment syndrome ; Computed tomography ; Carbonate-containing apatite ; Electron microscopy ; X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We present a patient whose ectopic calcification following deep posterior compartment syndrome was studied by electron microscopy, chemical analyses, and X-ray diffraction. The patient complained of a toe flexion deformity following a tibial fracture which he sustained 18 years earlier. Damage to the peroneal artery was demonstrated by magnetic resonance angiography, suggesting that the patient had had deep posterior compartment syndro-me in the past. A large radiopaque mass, identified in the flexor hallucis longus muscle by radiographs and computed tomography, was resected, resulting in a dramatic improvement of the toe deformity. The resected material was analyzed in detail. It included no osseous tissue, and was not birefringent under a polarizing microscope, being compatible with ectopic calcification rather than ossification. On electron microscopy the material was found to be an assembly of tiny rods. Chemical and X-ray diffraction analyses suggested a carbonate-containing apatite as the most probable substance.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2021
    Schlagwort(e): Key words Cristobalite ; Tridymite ; Phase transformation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Abstract Using minimum exposure techniques, it is feasible to perform high resolution electron microscopy on the α-cristobalite phase of (Si0.9 Ge0.1)O2, which is extremely radiation sensitive. Such images reveal atomic scale information of twins and tridymite-like stacking faults on (1 1 1)β planes, as well as of domain boundaries resulting from the β→α transition. Polytype structures are formed in certain cases. Morphological features suggest that the phase transformation cristobalite → tridymite proceeds by means of a zonal dislocation mediated synchro-shear process on (1 1 1)β planes; the geometry of this process is analyzed.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-0533
    Schlagwort(e): Key words Papillary ; Glioneuronal tumour ; Electron microscopy ; NCAM ; L1 adhesion molecule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Among the mixed glioneuronal tumours, a new variant called papillary glioneuronal tumour has recently been delineated. A case occurring in a 23-year-old man is reported. The tumour was cystic with a mural nodule enhanced by gadolinium injection. It was located within the left parieto-occipital lobe. Surgical excision showed a greyish friable tumour with cystic areas. Histopathological examination revealed a pseudopapillary component comprising a single layer of regular cells, arranged around hyalinised vessels. These cells were immunoreactive with anti-glial fibrillary acidic protein and HNK1 antibodies. A neurocytoma-like component coexisted with round blind cells and focal fibrillary rosettes. These cells were immunostained by anti-neuron-specific enolase and anti-synaptophysin antibodies. Neither mitoses nor ganglioid cells were seen. HNK1, the three isoforms of NCAM, and the L1 adhesion molecule were detected by Western blot analysis. Ultrastructural study showed three different types of cells. The first contained gliofilaments, the second showed long processes with true synapses, and the third was poorly differentiated. However, all had identical nuclei and contained dense bodies. These findings suggest a common origin for the tumour cells derived from a bipotential neuroglial progenitor. As for other mature mixed neuroglial tumours, the prognosis is good. Our patient is free of disease 7 years after complete surgical treatment.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-069X
    Schlagwort(e): Key words Fluorescence ; Photodynamic therapy ; Bromosulphophthalein ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The cellular uptake and subcellular localization of indocyanine green (ICG; absorption band 700– 850 nm), and cell survival and ultrastructural changes following ICG-mediated phototherapy were investigated in vitro in four different cell lines derived from human skin (SCL1 and SCL2 squamous cell carcinoma, HaCaT keratinocytes and N1 fibroblasts). The cellular uptake of ICG (1–50 μM, incubation times 1, 4, 24 h) was saturable, highly cumulative and could be inhibited by the addition of 250 μM bromosulphophthalein indicating the involvement of the organic anion transporting polypeptide (OATP). For HaCaT cells, the maximum cellular uptake (Vmax) and the Michaelis constant (Km) were 9.9 ± 1.1 mM and 47 ± 16 μM, respectively, following a 24-h incubation with ICG. Fluorescence microscopy revealed a cytoplasmic distribution of ICG, probably bound to glutathione S-transferase. Following irradiation with a cw-diode laser (805 nm, 80 mW/cm2) at doses of 24 or 48 J/cm2, the phototoxicity was determined using the MTT assay as a measure of cell viability. For all cell lines, ICG concentrations above 25 μM produced a significant phototoxic effect. The EC50 of ICG for HaCaT cells following irradiation at 24 J/cm2 was 20.1 ± 3.9 μM. Growth curves showed that even HaCaT cells treated at the EC50 were killed within a week following treatment. Electron microscopy 1 h after ICG-mediated phototherapy revealed cytoplasmic vesiculation, dilation of the rough endoplasmic reticulum, the Golgi complex and the perinuclear cisternae and the beginning of chromatin condensation in the nucleus. These ultrastructural findings are not consistent with a photothermal action of ICG-mediated phototherapy. Taken together with those of previous studies by our group these results support photooxidation as a major cell-killing mechanism.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 99 (2000), S. 39-47 
    ISSN: 1432-0533
    Schlagwort(e): Key words Sural nerve ; Muscle fiber diameter ; Morphometry ; Electron microscopy ; Myotonic ¶dystrophy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We compared peripheral nerve fibers and muscle fibers in myotonic dystrophy (MD) using a computer-assisted device for morphometry. In the 17 cases with MD studied, the sural nerves of 14 cases (82%) showed various degrees of reduction of the myelin sheath area (MSA) per endoneurial area. Of these, 8 cases (47%) presented with a mild reduction of the MSA, 5 cases (29.4%) with moderate reduction, and one case (6%) with severe reduction. The number of myelinated nerve fibers was not significantly reduced in MD when compared with control nerves, due to clusters of small regenerated nerve fibers. The mean diameter of the muscle fibers in 6 of the 17 cases was less than 40 μm. Of these 6 severely affected cases, ¶5 revealed a considerable reduction of the MSA. Other cases, which appeared to be normal in respect to the diameter of muscle fibers, showed various degrees of reduction of the MSA. Thus, there is usually, but not always a morphometric correlation of the severity of changes between peripheral nerves and muscle. The severity of the peripheral neuropathy appears to depend largely on the patient’s age, the stage of the disorder, and the time of progression. Electron microscopic examination of sural nerves showed significant, though non-specific pathological changes.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 99 (2000), S. 525-528 
    ISSN: 1432-0533
    Schlagwort(e): Key words Tubulovesicular particles ; Scrapie ; Electron microscopy ; Prion protein ; Transmissible ¶spongiform encephalopathy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Tubulovesicular bodies are structures, apparently specific to the transmissible spongiform encephalopathies, which are of unknown composition and significance. Prion protein (PrP) is absent from tubulovesicular bodies when tissues are examined by immunogold electron microscopy. In the F1 cross of C57 and VM mice (CVF1) infected with ME7 scrapie there is a marked degeneration of hippocampal CA1 neurons. In this model the earliest changes seen, at about 100 days post inoculation (dpi) are a degeneration of axon terminals and synaptic loss. Terminal disease is around 250 dpi. In blind coded trials we counted the number of tubulovesicular particles and estimated their density in 56–76 electron micrographs taken from the stratum radiatum of each of one or two CVF1 ME7-infected mice at 84, 100, 126, 154 and 181 dpi and from four normal brain inoculated control mice. Tubulovesicular particles were present from 98 dpi and the density of particles increased with increasing incubation period. The very early occurrence of tubulovesicular particles, before the presence of significant pathology, argues that tubulovesicular particles are a part of the primary disease and are not epiphenomena.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-1017
    Schlagwort(e): Key words X-ray crystallography ; Electron microscopy ; Biological databases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract Advances in structural biology are opening greater opportunities for understanding biological structures from the cellular to the atomic level. Particularly promising are the links that can be established between the information provided by electron microscopy and the atomic structures derived from X-ray crystallography and nuclear magnetic resonance spectroscopy. Combining such different kinds of structural data can result in novel biological information on the interaction of biomolecules in large supramolecular assemblies. As a consequence, the need to develop new databases in the field of structural biology that allow for an integrated access to data from all the experimental techniques is becoming critical. Pilot studies performed in recent years have already established a solid background as far as the basic information that an integrated macromolecular structure database should contain, as well as the basic principles for integration. These efforts started in the context of the BioImage project, and resulted in a first complete database prototype that provided a versatile platform for the linking of atomic models or X-ray diffraction data with electron microscopy information. Analysis of the requirements needed to combine data at different levels of resolution have resulted in sets of specifications that make possible the integration of all these different types in the context of a web environment. The case of a structural study linking electron microscopy and X-ray data, which is already contained within the BioImage data base and in the Protein Data Bank, is used here to illustrate the current approach, while a general discussion highlights the urgent need for integrated databases.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 100 (2000), S. 435-444 
    ISSN: 1432-0533
    Schlagwort(e): Key words Muscle transplantation ; Muscle ¶regeneration ; Electron microscopy ; Muscle spindles ; Motor innervation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Extensor digitorum longus (EDL) muscles from 2- to 28-day-old rats were grafted into EDL muscles of adult inbred recipients (n = 8). At 1–6 months after the operation, experimental muscles were excised and the ultrastructure and innervation of regenerated muscle spindles was examined. Regenerated muscle spindles (n = 36) in isografted EDL muscles contained 4.3 ± 0.2 (mean ± SEM) encapsulated muscle fibres. These “intrafusal” muscle fibres lacked nuclear bag and nuclear chain accumulations, which are characteristic of normal muscle spindles; thus, they rather resembled thin encapsulated extrafusal muscle fibres. In the same sample, myelinated axons were found in 33 (92%) muscle spindles, but no sensory terminals were found. These findings demonstrate that regenerated spindles in isografted EDL muscles were not reinnervated by spindle-specific sensory axons, but exclusively by motor axons. Typical intracapsular motor endplates (MEPs) were found in one third of regenerated spindles examined. Their motor terminals contained accumulated mitochondria and synaptic vesicles. As is characteristic for MEPs, axolemma and sarcolemma were separated by a synaptic cleft about 60 nm wide that contained a basal lamina. The underlying sarcolemma formed either small infoldings or none at all, and the subsynaptic area contained only small subsarcolemmal accumulations of mitochondria. It is apparent that the structures described here as “regenerated muscle spindles” do not perform their normal physiological function as stretch receptors because they lack the sensory innervation. The present results show that regeneration and reinnervation in heterochronous isografts corresponds to that previously described in autotransplanted free muscle grafts. The results also show that, during muscle spindle regeneration, intrafusal satellite cells develop into extrafusal-like muscle fibres, apparently due to their motor innervation.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Physics and chemistry of minerals 27 (2000), S. 480-494 
    ISSN: 1432-2021
    Schlagwort(e): Key words Olivine ; Grain boundary ; Partial melt ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Abstract The microstructure of olivine-olivine grain boundaries has been studied in experimentally deformed (1200–1227 °C, 300 MPa) partially molten olivine and olivine-orthopyroxene rocks. In-situ melting produced ∼1 vol% melt in all samples studied. Grain boundary analyses were carried out using a number of transmission electron microscopy techniques. The grain boundary chemistry in undeformed olivine-orthopyroxene starting material showed evidence for the presence of an intergranular phase along some, but not all, of the olivine-olivine boundaries. In the deformed samples, ultrathin Si-rich, Al- and Ca-bearing amorphous films have been observed along all investigated olivine-olivine grain boundaries. The chemistry of the grain boundaries, which is considered to be indicative for the presence of a thin film, was measured with energy-dispersive X-ray spectroscopy (EDX) and energy-filtering imaging. The amorphous nature of the films was confirmed with diffuse dark field imaging, Fresnel fringe imaging, and high-resolution electron microscopy. The films range in thickness from 0.6 to 3.0 nm, and EDX analyses show that the presence of Al and Ca is restricted to this ultrathin film along the grain boundaries. Because thin melt films have been observed in all the samples, they are thought to be stable features of the melt microstructure in deformed partially molten rocks. The transition from the occasional presence of films in the undeformed starting material to the general occurrence of the films in deformed materials suggests that deformation promotes the formation and distribution of the films. Alternatively, hot-pressing may be too short for films to develop along all grain boundaries. A difference in creep strength between the studied samples could not be attributed to grain boundary melt films, as these have been found in all deformed samples. However, a weakening effect of grain boundary melt films on olivine rheology could not be ruled out due to the lack of confirmed melt-film free experiments.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1432-0568
    Schlagwort(e): Key words Pheromone ; Supporting cell ; Vomeronasal organ ; Olfaction ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  To investigate cell turnover in the vomeronasal epithelium we used electron microscopy to obtain quantitative measurements of changes observed at the surface of the sensory epithelium. Receptor cell degeneration was induced by sensory nerve transection and animals were examined at postoperative recovery times of 2, 4, 6, 10, 15, 35 and 60 days. We measured the number and density of receptor and supporting cells, and membrane length at the surface of the sensory epithelium. The number of receptor cells rapidly decreased during the degeneration period, reaching a minimum at 6 days. After 15 days of recovery the number and density of receptor cells returned to control levels. The surface membrane length for regenerated receptor cells was similar to that of controls, however the morphological appearance was characteristic of immature cells. In contrast to the receptor cells, the number and density of supporting cells did not change during degeneration and regeneration. However, there was a significant increase in the length of supporting cell-surface membranes. These results suggest that during receptor cell degeneration, supporting cell membranes compensate for the loss of receptor cells by expanding their surface membrane length to help to maintain the continuity of the epithelial surface. Thus, an important role of vomeronasal supporting cells may be to maintain the structural integrity of the epithelium during turnover of the receptor cell population.
    Materialart: Digitale Medien
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  • 13
    ISSN: 1432-2307
    Schlagwort(e): Key words Gastrointestinal pacemaker cell tumor ; Interstitial cells of Cajal ; Gastrointestinal autonomic nerve tumor ; c-kit Receptor-antibody ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Recent studies indicate that a subgroup of gastrointestinal stromal tumors, including gastrointestinal autonomic nerve tumors (GANTs), originate from stem cells that differentiate toward a pacemaker-cell phenotype. These pacemaker cells form a complex network intercalated between the autonomic nerves and the muscle walls of the gastrointestinal tract and are called interstitial cells of Cajal (ICC). The c-kit receptor (CD117) is a sensitive marker for ICC. The aim of our study was to support the hypothesis that GANTs show ICC differentiation. Seven GANTs without convincing smooth muscle or neural differentiation all showed homogeneous reactivity for the c-kit receptor. CD34 was positive in three cases. On electron microscopy, the typical features of GANT were present. Six tumors contained skeinoid fibers. Most tumors were related to the small bowel. They presented as single (two cases) or multiple (five cases) tumors. The presenting symptoms were abdominal bleeding (2), abdominal mass (2), anemia (1), and small-bowel perforation (1). In two cases, liver metastases developed. Because of the close immunohistochemical and electron microscopic similarities of these tumors to the interstitial cells of Cajal, the term gastrointestinal pacemaker cell tumor seems appropriate.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Journal of orthopaedics and traumatology 1 (2000), S. 11-16 
    ISSN: 1590-9999
    Schlagwort(e): Key words Hydroxyapatite ; Bone ; Interface ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We performed a back-scattered electron microscopy analysis of the interface between newly formed bone and hydroxyapatite coating, in an experimental rabbit model. Twenty cylinders made of Ti6A14V and coated with hydroxyapatite at different crystallinity were implanted in the distal femural canal and retrieved at 4, 8, 26 an 34 weeks. Crystallinity of the coating varied from 90% to 60% and thickness varied between 50 and 100 μm. Osteocytes were detectable a few micrometers in proximity of the coating. They produced new bone which was so tightly apposed to the coating that high magnification BSEM did not resolve any discontinuity at the interface. This was not observed in uncoated implants. Degradation of the hydroxyapatite coating is not a simple hydrolytic process because newly formed bone is remodelled in areas were a tight apposition with hydroxyapatite is present. The coatint itself is likely to be attacked by the resorptive action of multinucleated giant cells and osteoclasts. In conclusion, response to coated samples is morphologically characterized by tight apposition with bone. The substitution of areas of the coating by newly formed bone is possible.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Neurological sciences 21 (2000), S. S63 
    ISSN: 1590-3478
    Schlagwort(e): Key words NCLs ; Peripheral biopsies ; Brain biopsy ; Blood lymphocytes ; Electron microscopy ; Pathological cytosomes ; Diagnostic criteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Clinical findings and pathological features of 28 patients affected with neuronal ceroid lipofuscinoses (NCL) are reviewed. The patient group included 15 children affected with the late-infantile form of NCL (LINCL), 10 patients affected with the juvenile form (JNCL), and 3 adult cases. Ultrastructural examinations of 50 biopsies from 6 tissues were consistent with clinical features in all LINCL and JNCL cases but one. The importance of electron microscopic (EM) examination of blood lymphocytes in these forms is outlined, particularly when combined with molecular analysis of the CLN2 or CLN3 genes, respectively. This approach leads to a definite diagnosis of LINCL and JNCL is a relatively short time. In adult NCL, diagnosis still relies on pathological grounds, and difficulties in interpreting the osmiophilic storage bodies in different tissues are outlined. EM investigation of blood lymphocytes was not helpful in any case of adult NCL. Results of one stereotactic brain biopsy are also reported.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1615-6102
    Schlagwort(e): Electron microscopy ; Photoreceptor ; Visual membrane ; Photic radiation damage ; Retina ; Crustacea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Visual membranes of the crayfish eye either belong to the small, distally placed rhabdomere of retinula cell R8 or are part of the much more voluminous proximal rhabdom, made up of rhabdomeres belonging to cells R1–R7. Under various conditions of environmental stress (e.g., prolonged darkness, elevated temperature, bright light with and without a concomitant rise in temperature, flickering lights) the visual membranes of R8 prove far more resistant to structural damage than those of R1–R7. Membrane damage is known to occur when dormant lipoxygenases become activated, for example through heat. Since R8 is the only type of visual cell in the crayfish retina that does not contain grains of screening pigment, the view that screening-pigment granules could “aggravate” or even “trigger” membrane damage in times of stress is strengthened. Functionally, R8's strong resistance to physical damage when exposed to flickering lights points to a role of the distal rhabdom in the movement detection system of the crayfish eye.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1619-0904
    Schlagwort(e): Poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC) ; In vivo biocompatibility ; Artificial endocrine pancreas ; Electron microscopy ; Glucose sensor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract Biocompatibility is important to assure a mild body reaction to an implanted device and its long-term stability and functionality. In diabetes research, subcutaneously implanted glucose monitoring systems need biocompatible surfaces for long-term application. The biocompatibility of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC), a material similar to the phospholipid layer of a cell membrane, was compared in vivo with the biocompatibility of polyurethane (PU), polyvinyl alcohol (PVA), and cuprophane (CUP). Needle-type glucose sensors and hollow-fiber probes used for microdialysis were coated with these four different biomaterials and implanted subcutaneously in 18 rats and 7 healthy volunteers. At set intervals, the implants and, in the case of the rats, also the surrounding tissue were removed and characterized by light and electron microscopy. MPC-coated sensors and hollow-fiber probes showed smooth and thin deposits in flat layers, whereas the surface deposits on PU- and PVA-coated sensors and those on CUP hollow-fiber probes appeared as rough, irregular, and dense attachments of aggregated cells and protein. This study confirmed results from earlier in vitro tests by showing the biocompatibility and reliability of MPC. Even though the amount of protein and cells attached to the MPC surface was not as low as expected from in vitro experiments, the biocompatibility and long-term stability of the implanted devices were superior to those of PU, PVA, and CUP.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Brain tumor pathology 17 (2000), S. 153-157 
    ISSN: 1861-387X
    Schlagwort(e): Chordoid meningioma ; Castleman syndrome ; Electron microscopy ; Immunohistochemistry ; Magnetic resonance image
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Chordoid meningioma is a relatively rare variant that is often associated with peritumoral lymphoplasmacellular infiltration causing Castleman syndrome (CS). We present a 44-year-old woman with chordoid meningioma not associated with CS. The patient presented with epilepsy and right hemiparesis (Todd's palsy) on admission. The radiological findings revealed an extraaxial mass lesion in the premotor cortex. They were compatible with a preoperative diagnosis of meningioma. No physical abnormalities related to CS were detected. A left frontal craniotomy was performed. The tumor surface was gelatinous, and it was totally resected with the attached dura mater (Simpson grade I). The patient had an uneventful recovery, and her seizures subsided. The pathological findings of the specimens revealed nests and cords of spindle and epithelioid cells with abundant myxoid matrix, mimicking the features of chordoma. On the basis of radiological, immunohistochemical, and electron microscopic findings, chordoid meningioma was verified, and a review of the literature was performed.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1437-773X
    Schlagwort(e): Key words Pigmented purpuric dermatitis ; Endothelial cell ; Fibrous long-spacing collagen ; Intracellular structure ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A case of pigmented purpuric dermatitis (PPD) in a Japanese man aged 59 years is reported with an interesting ultrastructural finding. Clinically, the lesions, which consisted of telangiectatic puncta and pigmentation, were irregular in shape and occurred predominantly on the lower legs without pruritus. Histologically, lymphocytic perivascular infiltrates and extravasation of red blood cells were observed in the papillary dermis. Ultrastructurally, endothelial cells with ovoid nuclei showed swelling and the lumen of the capillary became narrowed. Several banded structures, so-called fibrous long-spacing collagen (FLSC), were observed in the cytoplasm. They were spindle shaped, about 5 μm in length, and showed crossbands of 300-nm-wide intervals with fine intraperiodic bands. These structures were not observed in dermal connective tissue and fibroblasts. These results suggested that FLSC was synthesized in endothelial cells rather than being phagocytosed by endothelial cells, which might be helpful in investigating the etiology of PPD.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1437-773X
    Schlagwort(e): Key words Dental titanium implant ; Electron microscopy ; X-ray microanalysis ; Electron diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This study investigated the tissue response associated with dental titanium implants. The mandibular third and fourth premolars and first molar of three adult beagle dogs were extracted bilaterally. Healing was then allowed for 3 months. Six titanium implants were placed in the mandibles of a dog. Three weeks after the implantation, mandibular sections containing the implants were retrieved with the use of a bone saw and investigated by light and electron microscopy, X-ray microanalyzer, and electron diffraction. Scanning electron microscopic observation showed titanium particles on the implant–bone interface, and investigation by microanalyzer revealed titanium not only on the implant–bone interface but also in the bone tissue. Transmission electron microscopic observation and investigation by electron diffraction showed titanium in the bone matrix and cells other than macrophages. In this study, titanium particles from the dental implant were recognized morphologically in the surrounding bone tissue. Thus, study of the influence of titanium particles on the human body is needed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 21
    ISSN: 1433-0458
    Schlagwort(e): Schlüsselwörter Obstruktives Schlafapnoesyndrom ; nCPAP Therapie ; Nasenschleimhaut ; Elektronenmikroskopie ; Keywords Obstructive sleep apnea ; nCPAP-therapy ; Nasal mucosa ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Background and objective. The treatment success of nCPAP therapy (nasal continuous positive airway pressure) depends partly on the relief of symptoms and partly on long-term patient acceptance and the related avoidance of complications.Nasal complaints constitute the most frequently reported side effects and, together with problems of mask application, are among the primary factors causing an nCPAP-therapy to be prematurely discontinued. Patients/Methods. To assess the morphological changes of the nasal mucosa during nCPAP-therapy, we excised specimens of nasal mucosa tissue in twelve patients with obstructive sleep apnea syndrome (OSAS) both before and 3–10 months after establishing nCPAP-mask acceptance. The specimens were examined by electron microscopy. Results. In all these patients, acceptance of the CPAP mask marked the initial part of therapy. In addition, mucociliary clearance was assessed by the saccharin test before and after therapy. In all patients, the nasal epithelium underwent fundamental changes upon CPAP therapy, which became manifest as modifications in the shape of epithelial cells, conglutination and clumping of the microvilli, and the appearance of immunocompetent cells. Once patients were nCPAP mask compliant, mucociliary clearance was distinctly prolonged in all cases. Conclusions. A successful therapeutic concept should provide normalization of room temperature and air humidity once nCPAP mask compliance has been achieved, and include regular assessment of the condition of the mucosa in the upper respiratory tract. Only by these measures can nasal complications be countered or therapy be applied at an early stage.
    Notizen: Zusammenfassung Hintergrund und Fragestellung. Der Therapieerfolg einer nCPAP-Therapie (“nasal continuous positive airway pressure”) ist einerseits abhängig von der Linderung der Beschwerden und andererseits von der Langzeitakzeptanz und der hiermit verbundenen Vermeidung von Komplikationen. Nasale Beschwerden sind die häufigsten Nebenwirkungen und neben den Maskenproblemen die wichtigste Ursache, weshalb eine nCPAP-Therapie frühzeitig unterbrochen wird. Patienten/Methodik. Wir haben bei 12 Patienten mit einem obstruktivem Schlafapnoesyndrom Probeexzisionen aus der Nasenschleimhaut vor und 3–10 Monate nach Anpasssung der nCPAP-Maske entnommen und elektronenmikroskopisch untersucht. Bei all diesen Patienten war die Anpassung der nCPAP-Maske die Ersttherapie. Darüber hinaus wurde vor und nach der Therapie die mukoziliäre Clearance mit Hilfe des Saccharintests beurteilt. Ergebnisse. Bei allen Patienten kam es nach der nCPAP-Therapie zur grundlegenden Veränderungen des Nasenepithels mit Veränderung der Epithelzellenform, Verklebungen und Verklumpungen der Mikrovilli und auftreten von immunkompetenten Zellen. In allen Fällen war die mukoziliäre Clearance nach Anpassung der nCPAP-Maske deutlich verlängert. Schlussfolgerungen. Ein erfolgreiches Therapiekonzept sollte die Normalisierung der Raumtemperatur und Luftfeuchtigkeit gleich nach der Anpassung der nCPAP-Maske und die regelmäßige Beurteilung der Schleimhautverhältnisse der oberen Atemwege beinhalten. Nur somit können nasale Komplikationen aufgehalten oder frühzeitig therapiert werden.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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