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  • 1995-1999  (7,316)
  • 1985-1989  (5,778)
  • 1975-1979  (5,447)
  • General Chemistry  (16,229)
  • Electron microscopy
  • Ultrastructure
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  • 1
    Electronic Resource
    Electronic Resource
    Infraterminal spreading and extrajunctional expression of nicotinic acetylcholine receptors in denervated rat skeletal muscle (1999)
    Springer
    Experimental brain research 125 (1999), S. 426-434 
    Details
    ISSN: 1432-1106
    Keywords: Key words Acetylcholine receptor ; Nicotinic ; Denervation supersensitivity ; Neuromuscular junction ; α-Bungarotoxin ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Through the use of biotinylated-bungarotoxin and monoclonal antibodies, the nicotinic acetylcholine receptor (nAChR) was localized in the subneural apparatus of mammalian motor end plates of the flexor digitorum brevis muscle of the adult rat at the light and electron microscopic levels. Under normal conditions, nAChR was located in the primary post-synaptic membrane of the neuromuscular junction, and the depths of the junctional folds constituting the secondary post-synaptic membrane did not contain any nAChR. Up to 75 days after repeated transection of the related motor nerve (sciatic), there was no major alteration in the light-microscopic localization of junctional nAChR in the subneural apparatus, except for a moderate shrinkage and increased immunocytochemical reactivity of the subneural apparatus. At the electron microscopic level, however, immunocytochemical reactivity gradually occupied the entire extent of the secondary post-synaptic membrane, including the depths of the junctional folds, which exhibited extensive branching. In non-innervated portions of the muscle fibers, nAChR receptor appeared in a linear localization on the surfaces of denervated muscle fibers. This linear reaction was not continuous with the nAChR reaction of the motor end plates. It is concluded that denervation supersensitivity might not be due to spreading of junctional nAChR from the end-plate area, but rather to expression of nAChR in non-innervated portions of the muscle fiber and to the infraterminal (subsynaptic) spreading of nAChR into the depths of junctional folds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050699
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  • 2
    Electronic Resource
    Electronic Resource
    Electron microscopic and immunohistochemical studies of gastrointestinal stromal tumors (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 213-220 
    Details
    ISSN: 1437-773X
    Keywords: Key words Gastrointestinal stromal tumor ; Gastrointestinal autonomic nerve tumor ; Electron microscopy ; Immunohistochemistry ; Gastrointestinal tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sixteen gastrointestinal stromal tumors (GISTs) were studied by immunohistochemical analysis and an ultrastructural procedure. The tumor locations were as follows: esophagus (2), stomach (7), small intestine (3), and large intestine (4). Four of the lesions were classified as malignant, 2 as borderline, and 10 as benign. On the basis of the immunohistochemical analysis, the tumors were classified as follows: 1 as myogenic type, 2 as Schwann cell type, 8 as Cajal cell type (including 2 gastrointestinal autonomic nerve tumors, GANTs), and 5 as mixed-cell type. In each subtype the phenotype was compared to the ultrastructural findings. Myogenic and Schwann cell type revealed ultrastructurally smooth muscle differentiation and schwannian tumor. All 8 tumors of the Cajal cell type revealed interdigitating cytoplasmic processes with occasional clusters of filopodia. Two tumors were subdivided as GANT. Five tumors of mixed-cell type were composed of a mixture of cells with variable myogenic features or variable neural differentiation. We confirmed in this study that immunohistochemical analysis reflected electron microscopic findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050005
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  • 3
    Electronic Resource
    Electronic Resource
    Reduction of cytochemical ecto-ATPase activities in keratin 8-deficient FVB/N mouse livers (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 209-212 
    Details
    ISSN: 1437-773X
    Keywords: Key words Keratin ; Bile canaliculi ; Ecto-ATPase ; Transgenic mice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Keratin 8 (K8) and keratin 18 are the intermediate filament proteins that are expressed in hepatocytes. A K8-deficient FVB/N mouse is a unique animal model for assessing the contribution of keratin intermediate filaments (IFs) to the structural and functional integrity of hepatocytes. Hepatocytes from homozygous (−/−) K8-deficient mice manifest a reduced bile acid secretion and an increased fragility to mechanical stress and hepatotoxic drugs. Hepatocytes from heterozygous (+/−) mice are more susceptible to drug-induced injury. Immunofluorescent microscopy revealed that hepatocytes from (+/−) mice maintained K8 IFs and F-actin that are similar to those in wild-type (+/+) mouse hepatocytes. In (−/−) mouse hepatocytes, K8 protein was negative and F-actin presented a coarse and irregular pattern. Ecto-ATPase, detected by enzyme histochemistry and observed by electron microscopy, was reduced in the bile canaliculi of both (+/−) and (−/−) mouse livers, in comparison with that of (+/+) mouse livers. These results reveal for the first time different microscopical findings regarding the livers of these three genotypes. They also suggest that the reduction of ecto-ATPase plays a role in the increased fragility of (+/−) and (−/−) mouse livers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050004
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural and immunohistochemical study of small cell neuroendocrine carcinoma of the parotid gland (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 122-126 
    Details
    ISSN: 1437-773X
    Keywords: Key words Small cell neuroendocrine carcinoma ; Parotid gland ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of small cell neuroendocrine carcinoma of the parotid gland is presented with immunohistochemical and electron microscopic studies. Small cell neuroendocrine carcinoma is extremely rare and is often difficult to distinguish from malignant lymphoma, adenoid cystic carcinoma, and undifferentiated carcinoma. Under light microscopy, the tumor cells consisted of solid sheets and nests of small tumor cells. Immunohistochemically, they were positive for KL-1 and EMA, and focally positive for NSE and synaptophysin. Observation using an electron microscope showed membrane-bound neuroendocrine granules in some tumor cells. Histological evaluation indicated that the present case was small cell carcinoma of the parotid gland, showing a neuroendocrine variety.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050018
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  • 5
    Electronic Resource
    Electronic Resource
    Electron microscopic stereology of capillary endothelial cells and cardiomyocytes in artificially arrested canine hearts (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 151-160 
    Details
    ISSN: 1437-773X
    Keywords: Key words Heart ; Ultrastructure ; Capillaries ; Endothelium ; Stereology ; Cardioplegic solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In open heart surgery and transplantation, sufficient structural preservation of the myocardium immediately following cardioplegic arrest is a precondition for overcoming ischemia and for resumption of postischemic function. Therefore, we compared the protective effect of three clinically applied cardioplegic solutions with fibrillating and beating hearts using structural criteria. Left ventricular samples were taken from (1) beating, or (2) fibrillating or arrested hearts following coronary perfu-sion with (3) St. Thomas' Hospital solution, (4) histidine tryptophane ketoglutalate (HTK) (Custodiol), or (5) University of Wisconsin (UW) solution and fixed by immersion. Ultrastructural differences in the swelling of capillary endothelial cells and myocytes were quantitatively evaluated using stereological methods. Endothelial cells were somewhat more swollen after St. Thomas perfusion than those in beating and fibrillating hearts. HTK-arrested hearts showed significantly lower values for cellular edema than beating hearts. UW perfusion resulted in the (significantly) lowest degree of endothelial cell edema. Edematous changes in myocytes were significantly greater in St. Thomas-arrested hearts than in UW- or HTK-arrested hearts. Cardiomyocyte edema in beating and fibrillating hearts was comparable to that in St. Thomas-perfused hearts. Thus, the stereol-ogical analysis revealed significant differences between cardioplegic solutions in structural preservation of myocardial ultrastructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050022
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  • 6
    Electronic Resource
    Electronic Resource
    Secretory carcinoma of the breast: an immunohistochemical and ultrastructural study (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 50-56 
    Details
    ISSN: 1437-773X
    Keywords: Key words: Secretory carcinoma ; Breast ; Intracytoplasmic lumina ; Immnohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a rare case of secretory carcinoma of the breast in a 50-year-old Japanese woman. The patient had been aware of a right breast tumor for 8 years, but had left it untreated. The tumor enlarged in size and became painful, and she visited our hospital. Breast carcinoma was diagnosed, and mastectomy was performed. Histopathological examination revealed features of a secretory carcinoma characterized by prominent secretory activity in the glandular and microcystic spaces, with some areas showing a follicular pattern resembling the thyroid gland. The secretory material was PAS-positive and immunohistochemically α-lactalbumin-positive. Ultrastructurally, the tumor cell contained many secretory vacuoles in the cytoplasm. In addition, extracellular and intracytoplasmic lumina were conspicuous; these were lined by microvilli projection and contained secretory material. By flow cytometric analysis, the DNA index was 1.14, which was diploid, showing relatively low proliferative activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050008
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructure of Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8) in a primary effusion lymphoma cell line treated with tetradecanoyl phorbol acetate (TPA) (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 94-99 
    Details
    ISSN: 1437-773X
    Keywords: Key words KSHV ; HHV-8 ; TPA ; Ultrastructure ; Primary effusion lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8) has not yet been fully elucidated, although some findings have been reported using primary effusion lymphoma (PEL) cell lines, KS-1, harboring no Epstein–Barr virus (EBV) coinfection. In the present study, detailed fine structural examination of KSHV/HHV-8 was performed after stimulation of the PEL-derived cell line KS-1 with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in vitro. While unstimulated KS-1 cells contained a small number of intranuclear virus particles associated with no extracellular mature particles, KS-1 cells stimulated with TPA produced many extracellular mature particles as well as intranuclear particles, in addition to interesting tubulo-reticular structures and aggregated tubular structures in vesicles. The induced intranuclear particles were empty, doughnut shaped, and dense cored, with outer and inner diameters of 100–110 nm and 60–70 nm, respectively. Dense-cored extracellular mature particles were 150–160 nm in diameter, and some contained doughnut-shaped cores, together with a few megaloviruses, 260 nm in outer diameter. These findings indicate that KS-1 cells treated with TPA can produce extracellular mature particles as well as intranuclear particles, which were proven to be KSHV/HHV-8.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050014
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  • 8
    Electronic Resource
    Electronic Resource
    Docetaxel-induced apoptosis in the mitotic phase: electron microscopic and cytochemical studies of human leukemia cells (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 167-174 
    Details
    ISSN: 1437-773X
    Keywords: Key words Apoptosis ; Docetaxel ; Human leukemia cell ; DNA fragmentation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We induced apoptosis in cells of the human leukemia cell line HL-60 using an antitumor agent, docetaxel (Taxotere), and investigated apoptosis in various aspects using in situ end-labeling (ISEL) of DNA, DNA fragmentation assay, flow cytometry, and electron microscopy. Because it inhibits depolymerization of tubulin, docetaxel is thought to arrest the cell cycle at the mitotic stage and to exert an antitumor effect. In this study, accumulation of docetaxel-treated cells at the G2/M phase was detected using flow cytometry. On ISEL of DNA, DNA fragmentation was observed at the mitotic stage. On electron microscopy, the nuclei of apoptotic cells lost their nuclear membranes, as do cells at mitosis, demonstrating that the cells were arrested mainly at the M phase in the cell cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050024
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  • 9
    Electronic Resource
    Electronic Resource
    The protective effect of hepatocyte growth-promoting factor (pHGF) against carbon tetrachloride-induced acute liver injury in rats: an ultrastructural study (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 184-192 
    Details
    ISSN: 1437-773X
    Keywords: Key words pHGF ; HGF ; Acute liver injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The protective effect of hepatocyte growth-promoting factor (pHGF) against CCl4-induced acute hepatitis in rats was examined by light and electron microscopy. Hepatocyte growth-promoting factor, purified from infant pig liver in an active form, has been used clinically in patients with hepatitis in China. Four hours after administration of CCl4, a single dose of pHGF was administered intraperitoneally. Six hours after administration of CCl4, inhibition of CCl4-induced hepatic necrosis and hepatocytes with severely dilated endoplasmic reticula were evident in rats treated with pHGF. At 48 h post administration, most hepatocytes had recovered, and not only mitotic hepatocytes (10–13 mitotic cells/100) but also mitotic Kupffer cells were observed. At 72 h, it was evident that the differentiation of hepatic stellate cells (Ito cell) into myofibroblast-like cells and the development of fibrosis around the central veins was prevented by pHGF. These results suggested that (1) pHGF may stabilize cell membranes, (2) pHGF acts as a mitogen not only for hepatocytes but also for Kupffer cells, and (3) pHGF prevents fibrogenesis in the case of CCl4-induced liver injury by preventing the differentiation of hepatic stellate cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050026
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  • 10
    Electronic Resource
    Electronic Resource
    Changes in cerebral blood flow and blood brain barrier in the gerbil hippocampal CA1 region following repeated brief cerebral ischemia (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 175-183 
    Details
    ISSN: 1437-773X
    Keywords: Key words Cerebral blood flow ; Blood–brain barrier ; Repeated brief cerebral ischemia ; Hippocampal CA1 ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal damage and changes in cerebral blood flow (CBF) and the permeability of the blood–brain barrier (BBB) following repeated brief periods of ischemia were studied in Mongolian gerbils. The cerebral ischemia was produced by three repeated occlusions of bilateral common carotid arteries for 3 min at 1-h intervals. CBF and permeability of the BBB were examined with tracers (China ink and silver nitrate) at 1, 3, and 7 days post ischemia using light and electron microscopy. Three days after the reperfusion, significant extravasation of tracers, consequential reduction of CBF, extensive neuronal destruction, and intravascular platelet aggregation were observed. Such vascular changes in the CA1 region were more severe than those in the frontal cortex. These findings strongly support the view that microcirculatory disturbance may be a mechanism responsible for delayed neuronal death in the CA1 region of the hippocampus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050025
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  • 11
    Electronic Resource
    Electronic Resource
    Melanin pigmented oncocytic metaplasia of the nasopharynx (1999)
    Springer
    Virchows Archiv 434 (1999), S. 455-457 
    Details
    ISSN: 1432-2307
    Keywords: Key words Melanin ; Oncocytic metaplasia ; Nasopharynx ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A 64-year-old man presented with a history of discomfort of the throat of a few weeks’ duration. Nasoscopic examination revealed multiple small, brown pigmentations at the left suprapharynx, the base of the left nasal cavity and the pharyngeal openings of the auditory tube on both sides. Microscopically, the lesion showed a glandular pattern of oncocytic epithelium with abundant pigmented granules and melanophages in the surrounding stroma. Immunohistochemically, the dendritic cells in the basal layer were positive for S-100 protein. Electron microscopic study revealed numerous fully melanized melanosomes and hypertrophied mitochondria in the oncocytic cells. Oncocytic cells do not produce melanin for themselves, melanin granules apparently being transferred from the adjacent dendritic cells to the oncocytic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050366
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  • 12
    Electronic Resource
    Electronic Resource
    Ultrastructural study of the destructive and repair processes in pulmonary inflammation and following endobronchial laser therapy (1999)
    Springer
    Virchows Archiv 435 (1999), S. 13-19 
    Details
    ISSN: 1432-2307
    Keywords: Key words Inflammation of the lung ; Biopsy ; Ultrastructure ; Laser therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Examination of 127 biopsy specimens from 45 patients with inflammatory lung diseases showed changes consistent with increased permeability of the capillary endothelial cells as an initial stage in the development of the inflammatory reaction. Associated interstitial oedema, deformation of the interalveolar septa, and structural disorganization of alveolar epithelium cells occur, and local microcirculatory problems result in tissue hypoxia and fibrosis. The ultimate morphological picture is determined largely by the intensity of repair. Laser biostimulation minimizes the inflammation and stabilizes fibroplastic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050389
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  • 13
    Electronic Resource
    Electronic Resource
    Evaluation of muscle capillary basement membrane in inflammatory myopathy (1999)
    Springer
    Virchows Archiv 435 (1999), S. 58-61 
    Details
    ISSN: 1432-2307
    Keywords: Key words Capillary basement membrane ; Inflammatory myopathy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The capillary basement membranes from 16 skeletal muscle biopsies from patients with a clinical and histological diagnosis of inflammatory myopathy and from six controls were analysed ultrastructurally and morphometrically. Resin sections from 244 endomysial capillaries were examined by light microscope, and the results were correlated with findings seen in electron micrographs of these capillaries. The ultrastructural morphometric measurements and the statistical analysis showed that the capillary basement membrane was thick and multilaminated in 87% specimens affected by inflammatory myopathy. No thick or multilaminated basement membrane was observed in controls. In inflammatory myopathy the endomysial space next to the capillaries contained an increased amount of collagen fibrils and showed signs of a chronic reparative process. It is suggested that the thick multilaminated basement membrane in inflammatory myopathy represents an advanced stage of vascular regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050395
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  • 14
    Electronic Resource
    Electronic Resource
    The effects of cold-restraint stress on urinary bladder wall compared with interstitial cystitis morphology (1999)
    Springer
    Urological research 27 (1999), S. 454-461 
    Details
    ISSN: 1434-0879
    Keywords: Key words Cold-restraint stress ; Urinary bladder ; Interstitial cystitis ; Mast cell ; Urothelium ; Ultrastructure ; Ruthenium red ; Flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stress is associated with many diseases of unknown aetiology. This study demonstrates the effects of cold-restraint stress on the morphology of the urinary bladder. Additionally, it compares the results obtained with the morphology of the interstitial cystitis. The animals were subjected to three hours of cold-restraint stress and then starved for 48 h. The morphology and histochemistry of the urinary bladder was investigated with light and electron microscopy. The proliferative activity was analysed via flow cytometry. Increased and degranulated mast cells in the mucosa, leucocyte infiltration in the lamina propria, vacuole formation in the urothelial cells, loose tight junction, dilated intercellular spaces and altered proliferative activity were observed in the stress group when compared with the control. The increase in the number of mast cells and especially degranulated mast cells and vacuole formation and the loose tight junction of the urothelium correlated with the histopathological findings of interstitial cystitis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002400050135
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  • 15
    Electronic Resource
    Electronic Resource
    Bunina bodies in amyotrophic lateral sclerosis on Guam: a histochemical, immunohistochemical and ultrastructural investigation (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 150-156 
    Details
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Bunina body ; Guam ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An investigation of Bunina bodies is important when studying the pathoetiology and pathomechanisms involved in amyotrophic lateral sclerosis (ALS). It may serve as a clue essential for the study of the pathogenesis of Guamanian amyotrophic lateral sclerosis (ALS-G), and it may provide a means of answering the question of whether ALS-G is the same disease as classical ALS or a different entity. In ALS-G, however, no precise histochemical, immunohistochemical, or detailed ultrastructural examination has been published to date. To elucidate the pathological differences/similarities of Bunina bodies between classical ALS and ALS-G, we performed histochemical, immunohistochemical, topographic and ultrastructural examinations. Histochemically, hematoxylin and eosin, Masson’s trichrome, methylgreen-pyronin, phosphotungstic acid-hematoxylin, Klüver-Barrera, Bodian and periodic acid-Schiff staining were utilized. Immunohistochemical examination was performed using antibodies for cystatin C, ubiquitin, Tau-2, Cu/Zn superoxide dismutase, phosphorylated neurofilament and glial fibrillary acidic protein. Histochemical findings were consistent with those previously described for classical ALS. The immunohistochemical study showed that in ALS-G Bunina bodies were intensely labeled by an anti-cystatin C antibody. Topographic examination demonstrated that Bunina bodies were distributed in the spinal anterior horns and Clarke’s column in the spinal cord. Ultrastructurally, Bunina bodies were composed of electron-dense amorphous/ granular material accompanied by vesicular structures and neurofilaments. The results of the present study have revealed that the pathological features of Bunina bodies in ALS-G are identical to those seen in classical ALS. These findings strongly suggest that a similar degenerative process occurs in the spinal anterior horn cells in both ALS-G and classical ALS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051063
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  • 16
    Electronic Resource
    Electronic Resource
    Familial inclusion body myopathy with desmin storage (1999)
    Springer
    Acta neuropathologica 97 (1999), S. 509-514 
    Details
    ISSN: 1432-0533
    Keywords: Key words Hereditary inclusion body myopathy ; Desmin storage myopathy ; Ultrastructure ; Immmunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two adult familial cases of inclusion body myopathy (IBM) with desmin storage in skeletal muscle. Clinically, both patients presented late-onset, progressive, symmetrical, both proximal and distal muscle weakness. Muscle biopsy findings were identical in both cases and consisted of marked variability in fiber size, increased number of central nuclei and vacuolation involving 10% of fibers. Single or multiple vacuoles were located subsarcolemmally or in the center, and were rimmed by basophilic material. At the ultrastructural level, tubulofilamentous nuclear and cytoplasmic inclusions of 16–21 nm in diameter were frequently observed. In addition, large subsarcolemmal and central deposits composed of electron-dense granular material were present in many fibers. Immunocytochemistry revealed staining for desmin, vimentin and ubiquitin within both inclusions and vacuolated fibers. Possible structural and functional associations between these two types of muscle changes remain unclear. They may either represent two coexistent disease processes or merely reflect an abnormal form of muscle fiber degradation, with unidentifiable specificity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051021
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  • 17
    Electronic Resource
    Electronic Resource
    The anchoring zone in the human placental amnion: bunches of oxytalan and collagen connect mesoderm and epithelium (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 81-90 
    Details
    ISSN: 1432-0568
    Keywords: Key words Elastic fibre system ; Microfibrils ; Collagen type IV ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study deals with the examination of the elastic fibre system as well as collagen fibrils and collagen type IV in the amnion of the human chorionic plate of uncomplicated pregnancies at term. In organs other than placenta, the elastic fibre system comprises elastic fibres, elaunin and oxytalan microfibrils. The investigation was performed by light and electron microscopy and immunocytochemistry. Abundant oxytalan fibres were present in all amnionic layers, while no elastic fibres were found. Oxytalan microfibrils formed a broad subepithelial layer and were intermingled with collagen fibrils in the subjacent compact layer and in the amnionic mesoderm. Light microscopically, bunches containing orcein-stained oxytalan and collagen-type-IV-immunostained microfibrils were seen rising from the amnionic mesoderm perpendicularly towards the epithelial layer, where they obviously inserted. It can be assumed that the subepithelial microfibrillar layer and the following compact layer form an anchoring zone between the amnionic mesoderm and the epithelium that may contribute to the maintenance of strength. The ultrastructure of the bunches clearly showed collagen fibrils mixed with oxytalan microfibrils. No collagen type I-immunostaining was found in the bunches. After pretreatment of cryostat sections with elastase, oxytalan-orcein-staining was absent, but collagen type IV-immunoreactivity was not altered. Furthermore, after oxytalan-orcein-staining resp. anti-collagen type IV incubation, all positive fibres revealed an identical morphological pattern. We propose that oxytalan and collagen type IV may represent further members of the microfibril complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050262
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  • 18
    Electronic Resource
    Electronic Resource
    Subretinal macrophages in the developing eye of eutherian mammals and marsupials (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 551-558 
    Details
    ISSN: 1432-0568
    Keywords: Key words Retina ; Development ; Retinal pigment epithelium ; Microglia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Blood-borne mononuclear cells invade the developing retina via the hyaloid vasculature at the optic nerve head. Following removal of apoptotic cell debris they give rise to the network of resident microglia. The population of cells recently described in the peripheral subretinal space of developing human eyes may represent a further population of macrophages destined to become microglia. The aim of the present study was to confirm the presence of subretinal macrophages in the developing eye in other mammalian species and perform preliminary immunophenotypic analysis in rat tissues. The range of species chosen included eutherian mammals (rat and rabbit) and marsupials (wallaby and opossum). Ocular tissues from a range of developmental stages were studied by scanning electron microscopy and transmission electron microscopy. Distinctive networks of dendriform and pleomorphic macrophages were observed by scanning electron microscopy in the peripheral subretinal space of D2 rabbits, newborn and D2 rats and D75 wallaby. Transmission electron microscopic studies of D2 rabbit, newborn and D2 rat and all ages of North American opossum revealed cells with the ultrastructural features of macrophages in the peripheral subretinal space, cilio-retinal junction and between ciliary epithelial cells. Preliminary immunoperoxidase studies using a panel of anti-leukocyte monoclonal antibodies on frozen sections of rat ocular tissues (newborn, D2 and D4) revealed ED1+ Ox42+ ED2+ but Ox6– cells in the peripheral subretinal space, peripheral retina and ciliary body epithelia. The data confirms that subretinal macrophages are a feature of the developing eye in a broad range of mammalian species and immunophenotypic evidence leads the author to postulate that these cells arise from the ciliary body vasculature and may migrate into peripheral neural retina and mature into resident microglia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050303
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  • 19
    Electronic Resource
    Electronic Resource
    Motor neuron disease with predominantly upper extremity involvement: a clinicopathological study (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 645-650 
    Details
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Autopsy ; Electron microscopy ; Immunocytochemistry ; Motor ; neuron disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two autopsy cases of motor neuron disease (MND) patients with an unusual type of muscular atrophy predominantly affecting the shoulder girdle and the upper extremities with proximal dominance. Both patients are considered to be clinically categorized into the El Escorial suspected form of amyotrophic lateral sclerosis (ALS). At autopsy, they showed marked loss of spinal anterior horn cells accompanied by astrogliosis positively immunostained with anti-glial fibrillary acidic protein antibody at the cervical level. At the lumbosacral level, anterior horn neurons were relatively well preserved and Bunina bodies, ubiquitin-positive skein-like inclusions and Lewy body-like inclusions were observed in the remaining neurons. In one patient, brain stem motor neurons (nerves V, VII, XII) and motor cortex, including Betz cells, were also affected and the corticospinal tracts were degenerated at the level of the thoracic and lumbar spinal cord. Pathological findings of this patient are consistent with those of ALS. In the other patient, the motor cortex, brain stem motor nuclei and the corticospinal tracts were well preserved, which is pathologically compatible with progressive spinal muscular atrophy. These patients with such a peculiar pattern of progressive muscular atrophy should be placed in a subgroup of ALS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051131
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  • 20
    Electronic Resource
    Electronic Resource
    A developmental study using three antibodies (VOBM1, VOBM2, and VOM2): immunocytochemical and electron microscopical analysis of the luminal surface of the rat vomeronasal sensory epithelium (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 215-224 
    Details
    ISSN: 1432-0568
    Keywords: Key words Vomeronasal organ ; Microvilli ; Monoclonal antibody ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The development of the rat vomeronasal organ was studied morphologically and immunocytochemically, using the monoclonal antibodies (MAbs) VOBM1, VOBM2 and VOM2 that react with the luminal surface of the vomeronasal sensory epithelium. Postnatal day (P) 7, 14, 21, 28, 35 and adult animals were examined. The vomeronasal organ and the blood vessel of the organ markedly increased in size and the vomeronasal glands increased in number between P7 and P14. At P35, the shape of the vomeronasal organ was similar to that of the adult but its size was slightly smaller. Electron microscopy showed that only a few scattered microvilli were present on supporting cells, and receptor cells were immature at P7. At P21, well-branched microvilli of the receptor cells and many microvilli of the supporting cells were observed on the luminal surface of the sensory epithelium. At P35, most apical endings of supporting cells and receptor cells were covered with numerous microvilli. Less developed areas were also present at the luminal surface of the epithelium at P35. At P7, immunoreactivities of the three antibodies were observed as discontinuous thin-layered bands only on the luminal surface of the sensory epithelium and no immunoreactivity was observed in other regions of the vomeronasal organ. Immunoreactivities of the VOBM1, VOBM2 and VOM2 increased with age and were observed as continuous thin-layered bands on the luminal surface of the epithelium by P35. These finding suggest that the development of the vomeronasal organ continues after birth and that the organ may reach maturity just before puberty (P42–49).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050222
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  • 21
    Electronic Resource
    Electronic Resource
    A new combined Bodian-Luxol technique for staining unmyelinated axons in semithin, resin-embedded peripheral nerves: a comparison with electron microscopy (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 323-329 
    Details
    ISSN: 1432-0533
    Keywords: Key words Unmyelinated fibers ; Peripheral nerve ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Quantitation of unmyelinated fibers (UF) in peripheral nerves has classically relied upon ultrastructural morphometry. Because this method is time-consuming, it is not typically performed in routine analysis of nerve biopsies. We applied the Bodian-Luxol technique to detect unmyelinated axons by light microscopy on semithin sections from resin-embedded nerve tissue. Estimates were compared to ultrastructural counts. The staining appeared highly specific for axons. Excellent correlation was found between optic densities and the population of UF larger than 0.5 μm. The smallest profiles detected by light microscopy had a diameter close to 0.6 μm. This new technique is not a substitute for ultrastructural quantitative morphometry of UF, as very small unmyelinated axons, especially regenerating ones, can not be reliably visualized. However, it provides a valuable light microscopic method for evaluating axonal loss among UF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051088
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  • 22
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of phosphorylated eIF2α [eIF2α(P)] in rat dorsal hippocampus during reperfusion (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 493-505 
    Details
    ISSN: 1432-0533
    Keywords: Key words Ischemia ; Protein synthesis ; Translation ; Ultrastructure ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During post-ischemic brain reperfusion there is a substantial reduction of protein synthesis in selectively vulnerable neurons. Normal protein synthesis requires a functional translation initiation complex, a key element of which is eukaryotic initiation factor 2 (eIF2), which in a complex with GTP introduces the met-tRNAi. Phosphorylation of Ser51 on the α subunit of eIF2 [eIF2α(P)] generates a competitive inhibitor of eIF2B, thereby preventing the replenishment of GTP onto eIF2, thus blocking translation initiation. It has been shown that the conditional expression of an eIF2α mutant (Asp substituted for Ser51) imitating the negative charge of Ser51 (P) induces apoptosis. During the first 10 min of post-ischemic reperfusion, there is an approximately 20-fold increase in eIF2α(P) seen in the cytoplasm of CA1 hippocampal neurons, and, by 1 h, there is also accumulation of eIF2α(P) in the nucleus. We utilized post-embedding electron microscopical immunogold methods to examine the localization of eIF2α(P) during reperfusion. Immunogold particles (10 nm) were concentrated chiefly along the rough endoplasmic reticulum and in association with the membranes of the nuclear envelope in CA1 neurons. Aggregations of gold particles in the nucleus were concentrated: (1) within and around the nucleolus, (2) associated to strands of heterochromatin, and (3) along putative nuclear filaments. The presence of eIF2α(P) in the nucleolus probably reflects its association with nascent ribosomal subunits. The β-subunit of eIF2 has a zinc finger and polylysine blocks analogous to those on other proteins that affect transcription. The association of eIF2α(P) with chromatin may have important implications for transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051115
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  • 23
    Electronic Resource
    Electronic Resource
    Structural identification and characterization of arteries and veins in the placental stem villi (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 407-418 
    Details
    ISSN: 1432-0568
    Keywords: Key words Placenta ; Vascular wall ; Smooth muscle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The vascular wall structure in the human full-term placental villi of normal pregnancy was studied by means of light and electron microscopy with an improved technique of perfusion fixation and tissue preparation. We observed 81 sections of stem villi that showed cross-sectional profiles of paired vessels in their center. Both vascular walls contained a large amount of extracellular matrix and no elastic lamina between smooth muscle cells of the media, making identification of the artery and the vein quite difficult at first sight. We then noted that the density of the smooth muscle cell population was always considerably higher in one than the other, and identified the former as artery and the latter as vein on the basis of their connection with larger arteries and veins running on the chorionic plate. Between the paired vessels, the artery had a smaller caliber than the vein, and the ratio of venous to arterial caliber was distributed from 1.0 to 2.5. The thickness of media was usually thicker in the vein than in the artery. Clusters of elastic fibers were found occasionally in the media of arteries and veins, and basement membrane-like materials were associated frequently with the elastic fibers and were distributed widely in the media as well as in the adventitia. In the veins, the smooth muscle cells of the most superficial part of the media contained well-developed rough endoplasmic reticulum and Golgi apparatus, indicating differentiation to secrete extracellular matrices. The present study revealed the difference of wall structure between arteries and veins in the placental stem villi for the first time at the ultrastructural level, and suggested differentiation of venous smooth muscle cells, possibly by some influence from the luminal side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050239
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  • 24
    Electronic Resource
    Electronic Resource
    Immunohistochemical, conventional and immunoelectron microscopical characteristics of periodic acid-Schiff-positive granules in the mouse brain (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 31-38 
    Details
    ISSN: 1432-0533
    Keywords: Key words Polyglucosan body ; Periodic ; acid-Schiff-positive granules ; Mouse brain ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Periodic acid-Schiff-positive granules (PGs) appear in the mouse brains in relation to advancing age. The exact location and pathophysiological significance of PGs, however, are not fully understood. The incidence, staining properties, and topographical distributions of PGs in the brains of 17 AKR mice ranging in age from 7 to 18 months were examined histochemically and immunohistochemically using antibody KM279 raised against a polyglucosan. In addition, to define the precise site of PG formation, we investigated the brains of 4 AKR mice of 24 months of age using conventional and immunoelectron microscopy. PGs were seen in all mice examined and the levels were increased with age. The PGs were located predominantly in the hippocampus and, to a lesser extent, in the cerebellum and olfactory bulb. Immunohistochemically, PGs in the hippocampus and cerebellum were labeled uniformly with KM279. On immunoelectron microscopy with this monoclonal antibody, the fibrillar or membranous structures corresponding to PGs seen using light microscopy were labeled specifically with gold particles. With conventional electron microscopy, fibrillar or membranous structures were seen along with synaptic vesicles and dense-core granules. Moreover, around the cells containing PGs, a few synaptic junctions with neighboring cells were observed, indicating that the cells contributing to formation of PGs were neuronal cells. The positive immunoreactivity of AKR mouse PGs for the antibody KM279 suggests that the PGs and similar structures in other species may share a common antigenicity. Thus, it is assumed that PGs in AKR mice might result from some abnormalities in glucose metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051048
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  • 25
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    Electronic Resource
    Breached cerebral glia limitans-basal lamina complex in Fukuyama-type congenital muscular dystrophy (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 330-336 
    Details
    ISSN: 1432-0533
    Keywords: Key words Micropolygyria ; Electron microscopy ; Frontal lobe ; Perivascular space ; Dot-like structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have reported breaches of glia limitans (GL)-basal lamina (BL) complex with protruding neuroglial tissue in Fukuyama-type congenital muscular dystrophy (FCMD) fetus brain and suggested that some basic deficits in the GL-BL complex may have a pivotal role in formation of micropolygyria in FCMD. We therefore investigated the cerebral GL-BL complex in seven FCMD cases (12–27 years of age), in three cases of Duchenne muscular dystrophy (17–25 years of age) and in two non-neurological controls (28 and 33 years of age). The frontal lobe cortex was examined immunocytochemically using antibodies against collagen type IV and laminin in each case, and ultrastructurally in an adult case of FCMD. In FCMD, the BL of the cortical surface was frequently breached with protruding neural tissue that ultrastructurally showed frequent synapses, neurites that had parallel arranged microtubules, and astrocytic processes. The outermost surface of this tissue was only partly lined by a BL. In the region of the gyral adhesion of micropolygyria, the perivascular space of the apparently entrapped meningeal blood vessels was occupied by neuroglial tissue, which is assumed to have invaded through the occasionally seen breaches of the perivascular GL-BL complex. Electron microscopy of the intruding tissue showed frequent synapses, microtubule-containing neurites and astrocytic processes. No breached GL-BL complex was found in any of the non-FCMD cases. These findings indicate that in FCMD, the cerebral GL-BL complex continues to have a crucial deficit with resulting breaches through which neuroglial tissue protrudes, promoting adhesion of the adjacent cerebral gyri during brain development before and after birth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051089
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  • 26
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    Electronic Resource
    The visualization of a new class of traumatically injured axons through the use of a modified method of microwave antigen retrieval (1999)
    Springer
    Acta neuropathologica 97 (1999), S. 335-345 
    Details
    ISSN: 1432-0533
    Keywords: Key words Amyloid precursor protein ; immunoreactivity ; Axonal injury ; Microwave antigen retrieval ; Traumatic brain injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antibodies to the amyloid precursor proteins (APP) have become routine markers for detecting traumatically induced axonal injury (AI) in animals and man. Unfortunately, the techniques used to visualize these proteins are not compatible with routine electron microscopic (EM) analysis. In the current communication, we describe a method for the ultrastructural visualization of antibodies to APP and, using this method, we identify a previously unrecognized population of traumatically injured axons. Rats were subjected to an impact acceleration traumatic brain injury and allowed to survive 30 min to 3 h postinjury. The animals were then perfused, their brains sectioned on a vibratome and the sections prepared for immunocytochemistry using a computer-controlled microwave capable of temperature regulation. The use of temperature-controlled microwave energy unmasked APP antigenic epitopes without sacrificing ultrastructural detail. The APP antibody was found in two distinct populations of reactive axons that differed in size, morphology, location, and temporal progression. Comparable to previous descriptions, one population showed traumatically related reactive changes that led to swelling and disconnection. The other population, however, revealed unanticipated changes reflected in nodal and paranodal swelling of small continuous fibers that showed no evidence of disconnection during the time periods assessed. These studies provide new insight into the complexity of the pathobiology of AI, while describing a novel approach for enhancing APP immunoreactivity at the EM level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050996
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  • 27
    Electronic Resource
    Electronic Resource
    Synaptology and ultrastructural characteristics of laryngeal cricothyroid and posterior cricoarytenoid motoneurons in the nucleus ambiguus of the rat (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 301-311 
    Details
    ISSN: 1432-0568
    Keywords: Key words Intrinsic laryngeal motoneurons ; Cholera toxin HRP ; Ultrastructure ; Swallowing ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The laryngeal motoneurons innervating the cricothyroid muscle (CT) are located in the semicompact formation just ventral to the rostral part of the compact formation of the nucleus ambiguus. The motoneurons innervating the posterior cricoarytenoid muscle (PCA) are located in the loose formation. We retrogradely labeled the CT and the PCA motoneurons using cholera toxin subunit B-conjugated horseradish peroxidase, and determined the ultrastructure and synaptic organization of these neurons. The CT and the PCA motoneurons had the appearance of α-motoneurons, i.e., large, oval or polygonal cells containing well-developed organelles and a prominent spherical nucleus. Two kinds of neurons were recognized among the PCA motoneurons. The one (PCA-A) was significantly smaller than the other (PCA-B). The average number of axosomatic terminals in a section was significantly largest in the PCA-B (56.6), smaller in the PCA-A (36.0), and smallest in the CT (32.3) neurons. Most of the axosomatic terminals (64.7%) contained pleomorphic vesicles and made symmetric synaptic contacts (Gray’s type II) with the PCA-A neurons, while more than 60% contained round vesicles with asymmetric synaptic contacts (Gray’s type I) in the CT (69.5%) and the PCA-B (60.6%) neurons. A few terminals associated with subsurface cisterns were present on all laryngeal motoneurons. These results indicated that the CT motoneurons may receive mostly excitatory terminals, whereas the PCA muscle may be regulated by neurons having many inhibitory terminals, and neurons having many excitatory terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050281
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  • 28
    Electronic Resource
    Electronic Resource
    The cytoskeleton of the myenteric neurons during murine embryonic life (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 459-469 
    Details
    ISSN: 1432-0568
    Keywords: Key words Differentiation ; Electron microscopy ; Histochemistry ; Microtubules ; Neurofilaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The organization of the cytoskeleton has been studied during mouse differentiation in cells of the myenteric neuronal lineage. The entire gut was examined starting from day 12.5 of embryonic life (E12.5) until birth (P0). Immunocytochemistry was performed to evaluate the expression of five of the most represented neurofilaments proteins (the low, NF-L, medium, NF-M, and heavy, NF-H, molecular weight subunits, α-internexin and peripherin) and of two of the microtubule-associated proteins (MAP1 and MAP2a+2b). In parallel, the appearance in the differentiating myenteric neurons of filamentous and microtubular structures and their intracytoplasmatic distribution were observed under the electron microscope. A differential immunohistochemical expression of the structural proteins was found. Immature cells expressed α-internexin, peripherin, NF-M and MAP1 by day E12.5; α-internexin expression was strong in these cells, but gradually decreased with age and was practically absent in adulthood. Conversely, the expression of the other three proteins increased with cell differentiation and was still present in adulthood. NF-L and NF-H expression appeared later, by day E16.5, and was weak for the entire pre- and postnatal life. MAP2a+2b was never expressed. Under the electron microscope, at day E12.5 the cytoskeleton was already organized in filamentous and microtubular structures. At this age neurofilaments were few and mainly located in the cell processes, and microtubules were numerous and mainly assembled in the neuritic growth cones, together with synaptic vesicles. With ageing, neurofilaments and microtubules were ubiquitous in the neuron. Data obtained demonstrate that cytoskeletal proteins gradually accumulate in the cells of the neuronal lineage in parallel with the organization of the cytoskeletal structures, which in turn mediate important neural events by the earliest stages of murine embryonic life, including growth of nerve processes and initiation of axonal transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050244
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  • 29
    Electronic Resource
    Electronic Resource
    Light and electron microscopic immunohistochemical observations of p75 nerve growth factor receptor-immunoreactive dermal nerves in prurigo nodularis (1999)
    Springer
    Archives of dermatological research 291 (1999), S. 14-21 
    Details
    ISSN: 1432-069X
    Keywords: Key words p75 nerve growth factor receptor ; (p75 NGFr) ; Immunoreactivity ; Ultrastructure ; Prurigo nodularis ; Nerve fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prurigo nodularis is an inflammatory skin disease characterized by neurohyperplasia. Neurotrophins and their receptors play a critical role in nerve growth, differentiation, maturation and maintenance, including cutaneous nerve fiber growth and innervation. They may also be responsible for events related to the growth and differentiation control of keratinocytes. To explore the exact distribution of the p75 low-affinity nerve growth factor receptor (p75 NGFr) in the cutaneous nerve components, p75 NGFr immunofluorescence as well as ultrastructural immunohistochemical studies were performed on prurigo nodularis lesional skin and normal human skin samples. The immunofluorescence results revealed that nerve fibers and bundles were increased in number and size in lesional upper dermis with stronger p75 NGFr immunoreactivity than in the corresponding normal tissue. At the ultrastructural level, a lot of nerve fibers clustered together in the prurigo nodularis dermal tissue. The axons were enlarged and branched, but the axons themselves seldom showed any NGFr immunoreactivity. The Schwann cell bodies were extended and irregularly shaped, and tended to separate into many branches enveloping the axons. The Schwann cell membrane showed strong p75 NGFr immunoreactivity. The perineurium cells also revealed strong p75 NGFr immunoreactivity. The Schwann cells inside the perineurium were less p75 NGFr-immunoreactive than those outside the perineurium. The membrane of certain basal keratinocytes showed NGFr immunoreactivity as well. The present results indicate that overexpression of p75 NGFr in Schwann cells and perineurium cells could contribute to the neurohyperplasia in prurigo nodularis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050378
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  • 30
    Electronic Resource
    Electronic Resource
    Larva-adult relationships in an ancestral dipteran: A re-examination of sensillar pathways across the antenna and leg anlagen of Chaoborus crystallinus (DeGeer, 1776; Chaoboridae) (1999)
    Springer
    Development genes and evolution 209 (1999), S. 103-112 
    Details
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050232
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  • 31
    Electronic Resource
    Electronic Resource
    Megasporogenesis in Arabidopsis thaliana L.: an ultrastructural study (1999)
    Springer
    Sexual plant reproduction 12 (1999), S. 99-109 
    Details
    ISSN: 1432-2145
    Keywords: Key words Arabidopsis thaliana ; Megasporogenesis ; Meiosis ; Ultrastructure ; Cellular polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this study, megasporogenesis of the plant model Arabidopsis thaliana was investigated by electron microscopy for the first time. The data described here could constitute a reference for future investigations of Arabidopsis mutants. During the beginning of meiosis the megaspore mother cell shows a polarity created by unequal distribution of organelles in the cytoplasm. Plastids accumulate in the chalazal region and long parallel saccules of endoplasmic reticulum, small vacuoles and some dictyosomes are found in the micropylar region. Plasmodesmata are abundant in the chalazal cell wall. The nucleus is almost centrally localized and contains a prominent excentric nucleolus and numerous typical synaptonemal complexes. After the second division of meiosis the four megaspores are separated by thin cell walls crossed by numerous plasmodesmata and do not show significant cellular organization. The young functional megaspore is characterized by a large nucleus and a large granular nucleolus. The cytoplasm is very electron dense due to the abundance of free ribosomes and contains the following randomly distributed organelles: mitochondria, a few short saccules of endoplasmic reticulum, dictyosomes and undifferentiated plastids. However, there is no apparent polarity, except for the distribution of some small vacuoles which are more abundant in the micropylar region of the cell. The degenerating megaspores are extremely electron dense and do not show any substructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050178
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  • 32
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    Studies of lectin receptors of rat microglia in culture: receptor distribution and internalization (1999)
    Springer
    Experimental brain research 124 (1999), S. 89-99 
    Details
    ISSN: 1432-1106
    Keywords: Key words Microglial culture ; Brain macrophages ; Isolectin ; Ultrastructure ; Intracellular pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study examined the lectin labeling of diverse morphological forms of microglia in culture. Similar to amoeboid microglial cells in vivo, polymorphic microglia showed lectin labeling at their plasma membranes, as well as in a few cytoplasmic vesicles and vacuoles. This labeling pattern was observed in cultured microglia incubated with isolectin at 4°C for 30 min. Five minutes after the temperature was raised to 37°C, the surface lectin receptors appeared to be internalized, as shown by the occurrence of many subsurface lectin-labeled vesicles, vacuoles and tubule-like structures. With longer incubation (up to 1–2 h at 37°C), many lysosomes and a few trans-Golgi saccules and associated lysosome-like structures became labeled. Concomitant with these changes was a reduction of lectin labeling at the plasma, with labeling having vanished in most of the cells after 1–2 h of incubation. By 24 h, only a few cells retained surface lectin labeling. It appears, therefore, that irrespective of morphology, lectin labeling (including its intracellular pathway) of microglia in culture parallels that of amoeboid microglia in vivo. This would offer a useful model for the study of lectin turnover in microglia and help to explain the roles of such receptors in microglial differentiation and function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050603
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  • 33
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    Electronic Resource
    Recovery of synapses in axotomized adult cat spinal motoneurons after reinnervation into muscle (1999)
    Springer
    Experimental brain research 125 (1999), S. 19-27 
    Details
    ISSN: 1432-1106
    Keywords: Key words Nerve injury ; Nerve repair ; Retrograde reaction ; Regeneration ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Peripheral axotomy of adult cat spinal motoneurons induces a marked loss of synaptic boutons from the cell bodies and dendritic trees. The aim of the present study was to analyze the recovery of synaptic contacts in axotomized motoneurons following reinnervation into muscle. Adult cat spinal motoneurons were first deprived of their muscular contacts for 12 weeks and, then, allowed to reinnervate their target muscle. Two years later, regenerated motoneurons were labeled with horseradish peroxidase to allow quantitative ultrastructural analyses of the synaptic covering of the cell bodies and dendrites. Presynaptic boutons were classified according to their size and the shape of their synaptic vesicles. Results show that a recovery of synaptic covering occurs in the axotomized neurons after muscle reinnervation, but it affects various bouton types to different degrees. The number of S-type boutons synapsing with the soma was 70% higher after reinnervation than at 12 weeks after axotomy, while the number of F-type boutons had increased by only 13%. Compared with the normal situation, the number of S-type boutons synapsing with the proximal dendrites increased from 82% at 12 weeks after axotomy to 180% in the reinnervated state. In conclusion, in adult cat spinal motoneurons, the reestablishment of muscular contact is followed by a normalization of some of the synaptological changes induced by a prolonged state of axotomy. In certain respects restitution is incomplete, but in others it results in overcompensation.
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    URL: http://dx.doi.org/10.1007/s002210050653
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  • 34
    Electronic Resource
    Electronic Resource
    Magnetic properties of human liver and brain ferritin (1999)
    Springer
    European biophysics journal 28 (1999), S. 263-267 
    Details
    ISSN: 1432-1017
    Keywords: Key words Human liver ; Human brain ; Ferritin ; Electron microscopy ; Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Human brain (globus pallidus) and liver tissues were investigated by means of electron microscopy (EM), Mössbauer spectroscopy (MS) and SQUID magnetometry techniques. Based on MS measurements, the iron present was identified to be in the ferritin-like form (61–88%) and in the form of a low-spin iron species (the balance). Its overall concentration was estimated as 1.5(3) mg in the brain and 2.4(5) mg in the liver, per gram of lyophilized tissue. The average core diameter was determined by EM measurements to be equal to 7.5(1.3) nm for the liver and 3.3(5) nm for the brain. Magnetization measurements carried out between 5 and 300 K yielded an estimation of an average blocking temperature, KT BL, as equal to 6.7 K and 8.5 K for the liver and the brain, respectively. From the dependence of KT BL on the external magnetic field it was concluded that the ferritin-like cores in the studied samples can be regarded as non-interacting particles. Finally, the uniaxial magnetic anisotropy constant was determined to be 6×103 J/m3 for the liver and 4×104 J/m3 for the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050208
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  • 35
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    Electronic Resource
    Muscle and skin biopsies are a sensitive diagnostic tool in the diagnosis of CADASIL (1999)
    Springer
    Journal of neurology 246 (1999), S. 526-532 
    Details
    ISSN: 1432-1459
    Keywords: Key words CADASIL ; Cerebrovascular disease ; Skin biopsy ; Muscle biopsy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a microangiopathic syndrome. Although the defective gene has been identified, genetic analysis may be effort some due to its large size and various mutations. Providing a reliable diagnostic marker would therefore be helpful. Electron microscopy has revealed characteristic electron-dense granular deposits in the basal lamina of vessels of patients with CADASIL. We investigated the sensitivity of skin and muscle biopsies for diagnosing CADASIL. We examined 30 family members of three unrelated German families affected by CADASIL. In 14 of the 21 affected individuals we performed skin and muscle biopsies; two patients were clinically asymptomatic. Under electron microscopy all muscle and skin biopsy specimens showed patches of granular and electron-dense material in the basal layer of both arterioles and capillaries. These findings confirm that general microangiopathy is a typical feature of this syndrome and is present in the early phase of the disease with or without clinical manifestation. Thus, as electron microscopy of skin biopsy specimens can establish the diagnosis of CADASIL with high certainty, it may be considered the method of first choice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050398
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  • 36
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a Clostridium sp. with cinnamoyl esterase activity and unusual cell envelope ultrastructure (1999)
    Springer
    Archives of microbiology 172 (1999), S. 139-149 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsClostridium xylanolyticum ; Cinnamic acid ; Esterase ; Lignocellulose ; Sporogenesis ; Ultrastructure ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microorganisms that hydrolyse the ester linkages between phenolic acids and polysaccharides in plant cell walls are potential sources of enzymes for the degradation of lignocellulosic waste. An anaerobic, mesophilic, spore-forming, xylanolytic bacterium with high hydroxy cinnamic acid esterase activity was isolated from the gut of the grass-eating termite Tumilitermes pastinator. The bacterium was motile and rod-shaped, stained gram-positive, had an eight-layered cell envelope, and formed endospores. Phylogenetic analysis based on 16S rRNA indicated that the bacterium is closely related to Clostridium xylanolyticum and is grouped with polysaccharolytic strains of clostridia. A wide range of carbohydrates were fermented, and growth was stimulated by either xylan or cellobiose as substrates. The bacterium hydrolysed and then hydrogenated the hydroxy cinnamic acids (ferulic and p-coumaric acids), which are esterified to arabinoxylan in plant cell walls. Three cytoplasmic enzymes with hydroxy cinnamic acid esterase activity were identified using non-denaturing gel electrophoresis. This bacterium possesses an unusual multilayered cell envelope in which both leaflets of the cytoplasmic membrane, the peptidoglycan layer and the S layer are clearly discernible. The fate of all these components was easily followed throughout the endospore formation process. The peptidoglycan component persisted during the entire morphogenesis. It was seen to enter the septum and to pass with the engulfing membranes to surround the prespore. It eventually expanded to form the cortex, verification for the peptidoglycan origin of the cortex. Sporogenic vesicles, which are derived from the cell wall peptidoglycan, were associated with the engulfment process. Spore coat fragments appeared early, in stage II, though spore coat formation was not complete until after cortex formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050753
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  • 37
    Electronic Resource
    Electronic Resource
    Intimal-type primary sarcoma of the aorta (1999)
    Springer
    Virchows Archiv 435 (1999), S. 62-66 
    Details
    ISSN: 1432-2307
    Keywords: Key words Rhabdomyosarcoma ; Aorta ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report an intimal sarcoma presenting as an aortic aneurysm. A 68-year-old man suffered from chest pain and speech disturbance. Computed tomography showed a sacciform aneurysm of the aorta, which was resected, revealing a polypoid tumour measuring 1.5×2×2.5 cm projecting into the lumen. This proved to be a poorly differentiated high-grade sarcoma having morphological, immunophenotypic and ultrastructural features consistent with rhabdomyosarcomatous differentiation. Primary sarcomas of the aorta are extremely rare. Many cases have been diagnosed as ”intimal” on the basis of their site of origin, and they are not easy to classify from their histological pattern. Electron microscopy and the use of a more comprehensive panel of immunohistochemical markers should be applied in the histological classification of ”intimal” sarcoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050396
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  • 38
    Electronic Resource
    Electronic Resource
    Types, numbers and distribution of synapses on the dendritic tree of an identified visual interneuron in the brain of the locust (1999)
    Springer
    Cell & tissue research 296 (1999), S. 645-665 
    Details
    ISSN: 1432-0878
    Keywords: Key words Descending contralateral movement detector (DCMD) ; Identified neuron ; Vesicles ; Electron microscopy ; 3-D reconstruction ; Locust ; Schistocercagregaria (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The descending contralateral movement detector (DCMD), an identified descending interneuron in the brain of the locust Schistocerca gregaria has been investigated by using light and electron microscopy. We describe the fine structure, distribution and numbers of synapes that it receives from another identified brain neuron, the lobular giant movement detector (LGMD), and from unidentified neurons. The DCMD dendrites emerging from the integrative segment vary in form and number between individuals and sexes but always form a flattened dendritic domain. The arborizations and the integrative segment appear to be exclusively postsynaptic. Two types of synaptic contacts (Type 1 and 2) onto the DCMD can be discerned as having either round (Type 1) or pleiomorphic synaptic vesicles (Type 2) and by large (Type 1) or small (Type 2) subsynaptic appositions. Contact zones of Type 1 synapses are smaller than those of Type 2. LGMD-synapses are of Type 1 and occur intermingled with presynaptic sites of unidentified units. Some branches of the DCMD receiving input from unidentified units are devoid of contacting LGMD processes. Synapses of both types are randomly distributed over the DCMD integrative segment and at fibres with similar sizes.Type 1 synapses are much more frequent than Type 2 synapses and their number is negatively correlated with fibre diameter. For a whole DCMD dendritic arborization, a total of 8500 active zones of chemical synapses has been calculated, including a mininum of 2250 LGMD-synapses and about 1000 Type 2 synapses. The DCMD may thus receive a considerable amount of input from as yet unidentified neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051325
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  • 39
    Electronic Resource
    Electronic Resource
    Metaphase-specific cell death in meiotic spermatocytes in mice (1999)
    Springer
    Cell & tissue research 296 (1999), S. 359-369 
    Details
    ISSN: 1432-0878
    Keywords: Key words Apoptosis ; Electron microscopy ; Meiosis ; Spermatocytes ; Spermatogenesis ; Testis ; TUNEL ; Mouse (10 strains)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Apoptosis of male germ cells is a widespread but little-understood phenomenon in many animal species. The elucidation of its mechanisms could be useful in the understanding of male infertility. We have examined the distribution of dying cells with the terminal transferase-mediated nick-end labeling (TUNEL) method and by an electron-microscopic procedure in the testes of 10 mouse strains, viz., C57BL/10 (B10), SL/NiA (SL), C57BL/6 (B6), C3H/He (C3H), BALB/c (BALB), DBA2 (DBA), CBA/J (CBA), MRL/MpJ-+/+ (M+), MRL/MpJ-lpr/lpr (lpr), and wild-type NJL mice (Mus musculus musculus). In the testes of the B10, NJL, SL, B6, C3H, BALB, DBA, and CBA mice, very few TUNEL-positive cells are distributed in the seminiferous tubules, whereas in the testes of the M+ and lpr mice, many TUNEL-positive cells, which are restricted to stage XII seminiferous tubules, have been identified. The most important finding is that many metaphases of meiotic spermatocytes show a marked TUNEL-positive reaction. Some metaphases show apoptotic morphology electron-microscopically. These results suggest that the testes of MRL strains will provide a useful model for the study of the mechanism of metaphase-specific apoptosis in meiotic spermatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051296
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  • 40
    Electronic Resource
    Electronic Resource
    Articular chondrocytes and synoviocytes in a co-culture system: influence on reactive oxygen species-induced cytotoxicity and lipid peroxidation (1999)
    Springer
    Cell & tissue research 296 (1999), S. 555-563 
    Details
    ISSN: 1432-0878
    Keywords: Key words Chondrocyte ; Synoviocyte ; Co-culture ; Proliferation ; Lipid peroxidation ; Cytotoxicity ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Objective: A new co-culture system of rat articular chondrocytes and synoviocytes (HIG-82; cell line) was incubated with phorbol myristate acetate (PMA), H2O2 or a combination of Fe2+ and ascorbic acid to simulate inflammation-like radical attacks in articular joints. Methods: Chondrocytes were characterized by immunocytochemistry against collagen type II, transmission electron (TEM) and light microscopy. Lipid peroxidation was investigated by measuring thiobarbituric-acid-reactive material in the supernatants, cytotoxicity by determining release of lactate dehydrogenase and proliferation by measuring [3H]thymidine incorporation, culture protein and DNA. Results: PMA or Fe2+ and ascorbic acid induced lipid peroxidation in chondrocytes and synoviocytes that was decreased significantly in co-cultures. PMA and H2O2 dose dependently induced release of lactate dehydrogenase in chondrocytes, which was lowered in co-cultures or in previously co-cultured chondrocytes to a nearly basal level. In contrast, conditioned media of synoviocyte cultures showed no lowering effect on the radical-induced toxicity. Protection against H2O2-induced damage of cellular membranes by co-culturing was also shown by TEM. Synoviocytes released chondrocyte-stimulating growth factors spontaneously without previous interaction. Conclusion: Chondrocytes establish protective mechanisms against reactive oxygen species via an interaction with synoviocytes. Our co-culture model presents a possible way to study mechanisms of inflammation in articular joints under defined conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051317
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  • 41
    Electronic Resource
    Electronic Resource
    Ultrastructure and distribution dynamics of chloride cells in tilapia larvae in fresh water and sea water (1999)
    Springer
    Cell & tissue research 297 (1999), S. 119-130 
    Details
    ISSN: 1432-0878
    Keywords: Key words Chloride cells (mitochondria-rich cells) ; Teleost larvae ; Osmoregulation ; Immunohistochemistry ; Quantification ; Ultrastructure ; Oreochromis mossambicus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the α-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42–63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the ”mitochondria-poor” cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051339
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  • 42
    Electronic Resource
    Electronic Resource
    Peripheral synapses at identifiable mechanosensory neurons in the spider Cupiennius salei : synapsin-like immunoreactivity (1999)
    Springer
    Cell & tissue research 295 (1999), S. 13-19 
    Details
    ISSN: 1432-0878
    Keywords: Key words Mechanoreceptors ; Synaptic proteins ; Histochemistry ; Ultrastructure ; Slit sensilla ; Hair sensilla ; Cupiennius salei (Chelicerata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Indirect immunocytochemical tests were used at the light- and electron-microscopic levels to investigate peripheral chemical synapses in identified sensory neurons of two types of cuticular mechanosensors in the spider Cupiennius salei Keys.: (1) in the lyriform slit-sense organ VS-3 (comprising 7–8 cuticular slits, each innervated by 2 bipolar sensory neurons) and (2) in tactile hair sensilla (each supplied with 3 bipolar sensory cells). All these neurons are mechanosensitive. Application of a monoclonal antibody against Drosophila synapsin revealed clear punctate immunofluorescence in whole-mount preparations of both mechanoreceptor types. The size and overall distribution of immunoreactive puncta suggested that these were labeled presynaptic sites. Immunofluorescent puncta were 0.5–6.8 μm long and located 0.5–6.6 μm apart from each other. They were concentrated at the initial axon segments of the sensory neurons, while the somata and the dendritic regions showed fewer puncta. Western blot analysis with the same synapsin antibody against samples of spider sensory hypodermis and against samples from the central nervous system revealed a characteristic doublet band at 72 kDa and 75 kDa, corresponding to the apparent molecular mass of synapsin in Drosophila and in mammals. Conventional transmissionelectron-microscopic staining demonstrated that numerous chemical synapses (with at least 2 vesicle types) were present at these mechanosensory neurons and their surrounding glial sheath. The distribution of these synapses corresponded to our immunofluorescence results.Ultrastructural examination of anti-synapsin-stained neurons confirmed that reaction product was associated with synaptic vesicles. We assume that the peripheral synaptic contacts originate from efferents that could exert a complex modulatory influence on mechanosensory activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051208
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  • 43
    Electronic Resource
    Electronic Resource
    Androgen-induced changes in Leydig cell ultrastructure and steroidogenesis in juvenile African catfish, Clarias gariepinus (1999)
    Springer
    Cell & tissue research 297 (1999), S. 291-299 
    Details
    ISSN: 1432-0878
    Keywords: Key words Teleost fish ; Puberty ; Testes ; Sex steroids ; Ultrastructure ; Steroidogenesis ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The present report focuses on the mechanism(s) involved in the steroid-induced decrease of androgen production in immature African catfish testes that was observed in previous studies. Juvenile animals were implanted with Silastic pellets containing different 11-oxygenated androgens (11-ketotestosterone, KT; 11β- hydroxyandrostenedione, OHA; 11-ketoandrostenedione, KA), testosterone (T) or estradiol-17β (E2). Control groups received steroid-free pellets. Two weeks later, testis tissue fragments were either incubated with increasing concentrations of catfish luteinizing hormone (LH), or incubated with [3H]-pregnenolone ([3H]-P5) or [3H]-androstenedione ([3H]-A). Tissue fragments were also prepared for the quantitative assessment of Leydig cell morphology. Most of the parameters studied were not affected significantly by implantation of E2. Implantation of all androgens inhibited both the basal and the LH-stimulated androgen secretory capacity in vitro. This was associated with a reduced size of the Leydig cells and loss of half of their mitochondria. The studies on the metabolism of tritiated steroid hormones indicated that steroidogenic steps prior to 11β-hydroxylation, probably C17–20 lyase activity, were affected by all androgens. Although the effects of 11-oxygenated androgens and T on Leydig cells were mostly similar, previous work showed that only the 11-oxygenated androgens stimulated spermatogenesis, suggesting that distinct mechanisms of action are used by 11-oxygenated androgens and T. These mechanisms, however, seem to merge on the same target(s) to impair Leydig cell androgen production. Such a negative feedback mechanism may be of relevance in the context of the decline in androgen secretion per milligram testis tissue that accompanies the first wave of spermatogenesis in pubertal African catfish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051357
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  • 44
    Electronic Resource
    Electronic Resource
    The distribution and ultrastructure of class II MHC-positive cells in human dental pulp (1999)
    Springer
    Cell & tissue research 295 (1999), S. 151-158 
    Details
    ISSN: 1432-0878
    Keywords: Key words Class II MHC-positive cells ; Human leukocyte antigen-DR ; Dental pulp ; Dendritic cells ; Macrophages ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution and ultrastructure of class II major histocompatibility complex (MHC)-positive cells were investigated in human dental pulp, employing immunohistochemistry using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. HLA-DR-immunopositive cells, appearing spindle-like or dendritic in profile, were densely distributed throughout the dental pulp. Under the electron microscope, these cells exhibited various sizes of vesicles containing clear or opaque contents, multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. Some reactive cells possessed coated pits and vesicles including electron-dense materials, indicating an active endocytosis. At the periphery of the pulp tissue, the HLA-DR-immunopositive cells were predominantly situated in the subodontoblastic layer, with some located in the odontoblast layer and/or predentin and extending their cytoplasmic processes into the dentinal tubules. Cell processes of these cells occasionally made contact with several odontoblast processes in the same way as the nerve fibers in the predentin. These cells never contained the typical phagosomes frequently observed in the HLA-DR-immunoreactive macrophages in the subodontoblastic layer and the pulp core. The results suggest that the HLA-DR-immunopositive cells in the odontoblast layer and/or predentin have some regulatory function on the odontoblasts under physiological conditions, in addition to their involvement in the initial defense reaction after tooth injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051221
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  • 45
    Electronic Resource
    Electronic Resource
    Effect of high-level oxygen exposure on the peroxidase activity and the neuromelanin-like pigment content of the nerve net in the earthworm, Lumbricus terrestris (1999)
    Springer
    Cell & tissue research 295 (1999), S. 349-354 
    Details
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051241
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  • 46
    Electronic Resource
    Electronic Resource
    Op/op mice defective in production of functional colony-stimulating factor-1 lack macrophages in muscularis externa of the small intestine (1999)
    Springer
    Cell & tissue research 295 (1999), S. 485-493 
    Details
    ISSN: 1432-0878
    Keywords: Key words Immunohistochemistry ; Electron microscopy ; Interstitial cells of Cajal ; F4/80 ; CSF-1 ; Kit-receptor ; Mouse (op/op)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The osteopetrotic (op/op) mutant mouse possesses an inactivating mutation in the colony-stimulating factor-1 (CSF-1) gene, which results in the absence of certain macrophages and in osteopetrosis, following a lack of osteoclasts. Studies of the op/op mouse indicate that CSF-1-dependent tissue macrophages may belong to a trophic and/or scavenger subpopulation, which through their effect on other cell types can significantly affect tissue functions, and that cells which are CSF-1 independent have antigen presentation and immunological functions.We have previously identified a cell system of regularly distributed macrophages in the muscularis externa of the small intestine and wanted to extend these studies to the op/op mouse.The present investigations with light- and electron-microscopic methods using fluorescent dextran, methylene blue and immunohistochemistry (F4/80, anti-kit receptor, anti-CD3, anti-CD45R/B220) show that macrophages are absent from the muscle layers, with only an occasional macrophage present in the subserosa. In the lamina propria and submucosa, macrophage numbers are reduced. In all other respects the muscularis externa appears normal, including normal organization and number of interstitial cells of Cajal. Control and op/op mice both lack cells expressing CD3 (T lymphocytes), CD45R/B220 (B lymphocytes) and mast cells in the muscularis externa. This leaves the muscularis externa macrophages as the most likely source of local cytokine production under such conditions as postoperative ileus and intussusception in infants, where the muscularis externa appears to be one target of cytokines. We conclude that the lack of macrophages, combined with the preservation of otherwise normal structure, will make the op/op mouse a valuable model by which to assess the functions and relative importance of the muscularis externa macrophages in relation to intestinal motility under normal and pathological conditions.
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    URL: http://dx.doi.org/10.1007/s004410051254
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  • 47
    Electronic Resource
    Electronic Resource
    Survival of rat MCH (melanin-concentrating hormone) neurons in hypothalamus slice culture: histological, pharmacological and molecular studies (1999)
    Springer
    Cell & tissue research 297 (1999), S. 23-33 
    Details
    ISSN: 1432-0878
    Keywords: Key words Melanin-concentrating hormone neurons ; Lateral hypothalamic slice culture ; Immunocytochemistry ; Ultrastructure ; In situ hybridization ; Competitive RT-PCR ; Leptin assay ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Hypothalamic slices containing the lateral hypothalamic area (LHA) were prepared from 6- to 8-day-old rats and maintained in stationary culture for up to 35 days in order to analyse how well the melanin-concentrating hormone (MCH) neurons survived. As previously reported for other brain areas, this method yielded a long-term well-preserved organotypic organization. Light- and electron-microscopic investigations showed that differentiation continued and that synaptic contacts developed in vitro. After a period of elimination of damaged cells and fibres, most of the remaining neurons and glial cells retained a normal morphology throughout the culture period. MCH neurons, in particular, survived well as attested by the strong immunocytochemical and in situ hybridization signals still observed after several weeks. In a comparison with the day of explantation, competitive reverse transcription/polymerase chain reaction demonstrated the remarkable stability of the level of MCH mRNA at least until the 20th day in culture; after 30 days, the clear decrease in this level seemed to be correlated with a loss of MCH neurons, rather than with a decrease in MCH expression. After 10 days of culture, the incubation of slices in the presence of the hormone leptin (50 ng/ml) resulted in a strong decrease of MCH gene expression, suggesting that MCH neurons retained their physiological properties. Thus, the LHA slice stationary culture, especially between one and three weeks (i.e. after tissue stabilization and before extensive cell loss), appears to be a suitable method for physiological and pharmacological studies of these neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051330
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  • 48
    Electronic Resource
    Electronic Resource
    Caveolin and its cellular and subcellular immunolocalisation in lung alveolar epithelium: implications for alveolar epithelial type I cell function (1999)
    Springer
    Cell & tissue research 295 (1999), S. 111-120 
    Details
    ISSN: 1432-0878
    Keywords: Key words Caveolin ; Caveolae ; Lung ; Alveolar epithelial type I cell ; Immunocytochemistry ; Electron microscopy ; Confocal laser scanning microscopy ; Rat (CD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasmalemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051217
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  • 49
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    Electronic Resource
    Effects of reserpine on ECL-cell ultrastructure and histamine compartmentalization in the rat stomach (1999)
    Springer
    Cell & tissue research 295 (1999), S. 131-140 
    Details
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Gastrin ; Reserpine ; Organelles ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-storing ECL cells in the stomach play a key role in the control of acid secretion. They contain granules, secretory vesicles and microvesicles, and sustained gastrin stimulation results in the additional formation of vacuoles and lipofuscin bodies. The cells are rich in the vesicle monoamine transporter type-2 (VMAT-2), which can be inhibited by reserpine. The present study examines the effect of reserpine on ECL-cell ultrastructure and histamine compartmentalization. Rats received reserpine and/or gastrin. Reserpine was given twice by the intraperitoneal route (25 mg/kg once daily). Gastrin-17 was given by subcutaneous infusion (5 nmol/kg/h), starting at the time of the first reserpine injection and continuing for 4 days when the rats were killed. At this stage, histamine in the oxyntic mucosa was unaffected by reserpine but elevated by gastrin. Immunocytochemical analysis (confocal microscopy) showed ECL-cell histamine in control and gastrin-treated rats to be localized in cytoplasmic organelles (e.g., secretory vesicles). After treatment with reserpine alone or reserpine+gastrin, ECL-cell histamine occurred mainly in the cytosol. Planimetric analysis (electron microscopy) of ECL cells showed reserpine to increase the number, size and volume density of the granules and to reduce the size and volume density of the secretory vesicles. Gastrin reduced the number and volume density of granules and secretory vesicles, increased the number and volume density of microvesicles and caused vacuoles and lipofuscin bodies to appear. Reserpine+gastrin increased the number, volume density and size of the granules. Reserpine prevented the effects of gastrin on secretory vesicles, vacuoles and microvesicles, but did not prevent the development of lipofuscin. Our findings are in line with the views: (1) that preformed cytosolic histamine is taken up by granules/secretory vesicles via VMAT-2, that histamine is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement and (2) that vacuoles are formed by the fusion of large secretory vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051219
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  • 50
    Electronic Resource
    Electronic Resource
    Structure and function of the human oocyte-cumulus-corona cell complex before and after ovulation (1999)
    Springer
    Protoplasma 206 (1999), S. 270-277 
    Details
    ISSN: 1615-6102
    Keywords: Cumulus oophorus ; Ovarian follicle ; Fertilization ; Ultrastructure ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of the human cumulus oophorus has been reviewed on the basis of scanning and transmission electron microscopic observations as well as of immunofluorescence data. Tissues sampled from preovulatory ovarian follicles and cumulus-enclosed oocytes and fertilized eggs (collected from the oviduct or obtained during in vitro fertilization procedures) have been evaluated from a microtopographic and morphodynamic point of view in order to better clarify the possible role of this population of cells. In particular, the following aspects have been studied and discussed: the presence of multiple close contacts (modulated by the interposition of the zona pellucida) between the oocyte surface and the long microvillous evaginations projecting from the inner aspect of corona cells surface (through these structures the intraovarian cumulus oophorus may control oocyte growth and metabolism up until the time of ovulation); the occurrence of different subpopulations of cells (steroid-synthetic cells, cells producing adhesive proteins, leukocytes, macrophages) in the postovulatory, extraovarian cumulus oophorus surrounding oocytes, zygotes and early developing embryos. All these elements found in the cumulus mass may positively act, through their paracrine activities, on the chemical composition of the microenvironment in which fertilization occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288215
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  • 51
    Electronic Resource
    Electronic Resource
    Ultrastructural study of the relationship between generative and vegetative cells inMagnolia ×soulangeana Soul.-Bod. pollen grains (1999)
    Springer
    Protoplasma 206 (1999), S. 87-96 
    Details
    ISSN: 1615-6102
    Keywords: Plasmalemmic cord ; Pollen grain ; Ultrastructure ; Magnolia ×soulangeana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InMagnolia ×soulangeana pollen grains the generative cell (GC) does not become totally free within the vegetative cell (VC), at least until the pollen tube emergence. Due to a deviation in its detachment process from the sporoderm, the opposing ends of the VC plasmalemma do not fuse themselves when the GC moves away from the intine. Consequently, the interplasmalemmic space surrounding the GC does not become isolated but rather maintains continuity with the sporoderm through a complex formation that we have called plasmalemmic cord. The real existence of this formation was confirmed through serial sectioning showing the plasmalemmic cord to consist of the VC plasmalemma. In its initial portion it is occupied by a reasonably accentuated wall ingrowth of the inner layer of the intine (intine 3). In the remainder portion, neither of the cytochemical tests used in this work have revealed the presence of a significant amount of wall material. However, ultrathin sections of samples processed either chemically or by cryofixation showed the existence of an intricate system of tubules and vesicles, some of which are evaginations of the VC plasmalemma. The hypothesis that the plasmalemmic cord may have a role in the complex interactions between the two pollen cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279255
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  • 52
    Electronic Resource
    Electronic Resource
    Anatomical and ultrastructural changes of the floral nectary ofPisum sativum L. during flower development (1999)
    Springer
    Protoplasma 206 (1999), S. 57-72 
    Details
    ISSN: 1615-6102
    Keywords: Anatomy ; Floral nectary ; Modified stomata ; Phloem ; Pisum sativum ; Stereology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The floral nectary ofPisum sativum L. is situated on the receptacle at the base of the gynoecium. The gland receives phloem alone which departed the vascular bundles supplying the staminal column. Throughout the nectary, only the companion cells of the phloem exhibited wall ingrowths typical of transfer cells. Modified stomata on the nectary surface served as exits for nectar, but stomatal pores developed well before the commencement of secretion. Furthermore, stomatal pores on the nectary usually closed by occlusion, not by guard-cell movements. Pore occlusion was detected most frequently in post-secretory and secretory glands, and less commonly in pre-secretory nectaries. A quantitative stereological study revealed few changes in nectary fine structure between buds, flowers secreting nectar, and post-secretory flowers. Dissolution of abundant starch grains in plastids of subepidermal secretory cells when secretion commenced suggests that starch is a precursor of nectar carbohydrate production. Throughout nectary development, mitochondria were consistently the most plentiful organelle in both epidermal and subepidermal cells, and in addition to the relative paucity of dictyosomes, endoplasmic reticulum, and their associated vesicles, the evidence suggests that floral nectar secretion inP. sativum is an energy-requiring (eccrine) process, rather that granulocrine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279253
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  • 53
    Electronic Resource
    Electronic Resource
    Ultrastructural features of the myocardium of children with dilated cardiomyopathy (1999)
    Springer
    Heart and vessels 14 (1999), S. 52-56 
    Details
    ISSN: 1615-2573
    Keywords: Endomyocardial biopsy ; Dilated cardiomyopathy ; Children ; Ultrastructure ; Basal lamina layering of capillary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We analyzed the electron-microscopic features of endomyocardial biopsy from pediatric patients with dilated cardiomyopathy (DCM). The specimens examined were taken from the right ventricle of ten patients aged from 2 to 15 years (mean 9.7 years). Biopsy specimens from eight patients with congenital heart disease (tetralogy of Fallot), aged from 3 to 12 (mean 7.3 years), and ten adult patients with DCM, aged from 32 to 60 (mean 45 years), were also examined. Patients considered to have endocardial fibroelastosis, arrhythmogenic right ventricular cardiomyopathy, specific cardiomyopathy, or coronary heart disease were excluded from this study. Specimens from pediatric patients with DCM showed various degrees of ultrastructural abnormalities of myocytes, including myofibrillar fragmentation, mitochondrial abnormalities, and intracellular edema. The ultrastructurally determined contractility failure index based on the severity of myocardial degeneration at the electronmicroscopic level was 4.9 ± 1.1. This value was significantly higher than that in patients with tetralogy of Fallot (0.9 ± 0.6,P 〈 0.001) but was not significantly different from that in adult patients with DCM (6.1 ± 2.6). The index of pediatric patients with DCM who died within 3 years was high (6.0 ± 0.8). Basal lamina layering of a capillary (BLL) in the myocardium was revealed in 1 of the 10 (10%) pediatric patients with DCM and in 6 of the 10 (60%) adult patients with DCM (P 〈 0.05). No BLL was noted in the patients with tetralogy of Fallot. These findings may be related to the pathogenesis of DCM in children and adults.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02481742
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  • 54
    Electronic Resource
    Electronic Resource
    Distribution and transmission of endosymbiotic microorganisms in the oocytes of the pig louse,Haematopinus suis (L.) (Insecta: Phthiraptera) (1999)
    Springer
    Protoplasma 209 (1999), S. 207-213 
    Details
    ISSN: 1615-6102
    Keywords: Endosymbiont ; Mycetocyte ; Mycetome ; Oocyte ; Transovarial transmission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All anoplurans live symbiotically with prokaryotic microorganisms hosted in specialized cells, termed mycetocytes. In nymphs and males mycetocytes are distributed between midgut epithelial cells. In females, besides the midgut, mycetocytes are found in the reproductive organs where they are located at the base of ovarioles in contact with lateral oviducts. The mycetocyte-associated symbionts are transmitted from one generation to the next transovarially. Here, the results of histological and ultrastructural studies on the distribution and transmission of symbiotic microorganisms within the ovaries of the anopluranHaematopinus suis are presented. Interestingly, during advanced oogenesis (i.e., choriogenesis) of this species all symbionts are localized extracellularly and form a tight mass located at the posterior pole of the oocyte just below the hydropyle. In insects studied so far, such localization of transovarially transmitted microorganisms has been reported only in the closely related speciesHaematopinus eurysternus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01453449
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  • 55
    Electronic Resource
    Electronic Resource
    Phase and aggregation behaviour of double-chain cationic surfactants from the class of N-alkyl-N-alkyl′-N, N-dimethylammonium bromide surfactants (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 856-867 
    Details
    ISSN: 1435-1536
    Keywords: Key words Double chain surfactants ; Aggregates ; Phase diagrams ; Lamellar phases ; Electron microscopy ; SANS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C x C y DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050462
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  • 56
    Electronic Resource
    Electronic Resource
    Outbreaks of gastroenteritis caused by SRSVs from 1987 to 1992 in Kyushu, Japan: Four outbreaks associated with oyster consumption (1999)
    Springer
    European journal of epidemiology 15 (1999), S. 175-180 
    Details
    ISSN: 1573-7284
    Keywords: Electron microscopy ; Epidemiology ; Non-bacterial Gastroenteritis ; Oyster ; Small round structured viruses (SRSVs)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From 1987 to 1992, 18 outbreaks of acute non-bacterial gastroenteritis occurred in Kyushu district. The most common symptoms were diarrhea, vomiting, nausea and abdominal cramp. Small round structured viruses (SRSVs) were detected in 52 (44.8%) of 116 stool samples from 17 outbreaks by the electron microscopy (EM) method, and a significant increase in the antibody level was noted in 42 (80.7%) of 52 paired serum samples from 12 outbreaks by the immune electron microscopy (IEM) method and in 18 (51.4%) of 35 samples from 8 outbreaks by the western blot (WB) method. However, according to the WB method, antigen-antibody reaction was not observed to reference antigen strips (SRSV-9/Tokyo 86-510, 63kDa) in three of the 8 outbreaks. The detected virus was regarded as an etiologic agent for these outbreaks. In four of 5 outbreaks which appeared associated with eating raw oysters, there was a close relation between SRSV infection and consumption of raw oysters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007543924543
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  • 57
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    Electronic Resource
    Synthesis of colloids and films of Pr, Er and Yb with nonaqueous solvents (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 164-173 
    Details
    ISSN: 1435-1536
    Keywords: Keywords Nanostructures ; Thin films ; Vapor deposition ; Electron microscopy ; Optical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Colloidal dispersions of Yb, Er and Pr have been prepared by chemical liquid deposition. The metals were cocondensed at 77 K with 2-methoxyethanol and ethanol to produce solvated metal atoms. The particle size of the dispersions was determined by transmission electron microscopy to range from 52 to 1080 Å; the particles had spherical shapes. After solvent evaporation under vacuum, active solids and amorphous powder were deposited over Cu and Al metal. Dispersion stability, particle size, UV/Vis absorption and zeta potential were studied. The solids prepared by solvent evaporation were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The films prepared on Al were studied by scanning electron microscopy. The most stable colloid was obtained using 2-methoxyethanol: several concentrations were stable for several months and the zeta potential indicated that this colloid stability is mainly due to solvation effects. FTIR spectroscopy of the solids indicated solvent incorporation in the film. This observation was corroborated by thermal analysis. Information on the thermal stability of the films was obtained by TGA. The UV/Vis absorption spectrum was measured at several concentrations under different conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050381
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  • 58
    Electronic Resource
    Electronic Resource
    A comprehensive analysis of selected diagnostic methods with respect to their usefulness in evaluating the biology of neoplastic cells in patients with laryngeal cancer (1999)
    Springer
    European archives of oto-rhino-laryngology and head & neck 256 (1999), S. 306-311 
    Details
    ISSN: 1434-4726
    Keywords: Key words Laryngeal cancer ; p53 ; Oncoprotein ; Ki67 ; Proliferating cell nuclear antigen (PCNA) ; DNA ploidy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The difficult and complicated mechanism of cancer development with little knowledge about the biology of existing cancers can lead to a permanent search for new examination techniques to improve the precision of life expectancy in patients and the selection of the most efficient methods of treatment. The aim of this study was to analyze certain prognostic factors, i.e., p53, Ki67, proliferating cell nuclear antigen (PCNA), DNA ploidy and cell proliferating activity, as well as the degree of morphological differentiation and cell maturity evaluated on an ultrastructural level in patients with laryngeal cancers in connection with data obtained from follow-up examinations and the clinical course of the disease. Neoplastic tissue was taken from 120 patients with laryngeal cancers. All underwent surgical treatment, radiotherapy and combined treatment in the Department of Otolaryngology, Karol Marcinkowski University School of Medical Sciences, Poznań, Poland, and the Department of Otolaryngology – Head and Neck Surgery, Haukeland University, Bergen, Norway. Before beginning treatment all patients underwent histological verification of their neoplastic tissues. Histopathological examination proved that the majority of cases (95%) had a squamous cell carcinoma. The occurrence of changes within the lymph nodes of the neck (N) was significantly correlated with T, S, Ki67, metastases to lymph nodes, DNA ploidy, site and surgery performed. The degree of clinical progression (S) was intercorrelated with T, N, p53, Ki67, PCNA, DNA ploidy, site and laryngectomy. The occurrence of oncoprotein p53 in neoplastic cells was measured by the staining degree of their nuclei and was correlated with T, S, DNA ploidy, metastases to lymph nodes, PCNA and site. The degree of staining of neoplastic cells for the nuclear antigen Ki67 was correlated to T, N, G, S, DNA ploidy, metastases to lymph nodes and surgical treatment. The proliferative antigen PCNA in the examined population of patients was intercorrelated with T, p53, Ki67, metastases to lymph nodes and surgical treatment. The results obtained from DNA flow cytometry could be associated with N, G, p53, Ki67 and metastases to lymph nodes. On the basis of the results obtained, the techniques suggested for the morphological and biological evaluation of neoplastic cells in cancer of the larynx should include TNM classification + G + DNA + p53 + Ki67.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004050050252
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  • 59
    Electronic Resource
    Electronic Resource
    Electrophysiological and ultrastructural correlates of cryoinjury in sciatic nerve of the freeze-tolerant wood frog, Rana sylvatica (1999)
    Springer
    Journal of comparative physiology 169 (1999), S. 351-359 
    Details
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Sciatic nerve ; Cryoinjury ; Dehydration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at −2.5 °C, −5.0 °C, or −7.5 °C. All frogs frozen at −2.5 °C, and most frogs (71%) frozen at −5.0 °C, recovered within 14 h after thawing began; however, frogs did not survive exposure to −7.5 °C. Sciatic nerves isolated from frogs frozen at −7.5 °C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to −2.5 °C or −5.0 °C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at −2.5 °C or −5.0 °C had little or no effect on tissue and cellular organization, but that (lethal) exposure to −7.5 °C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050231
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  • 60
    Electronic Resource
    Electronic Resource
    Echinococcus granulosus: praziquantel treatment against the metacestode stage (1999)
    Springer
    Parasitology research 85 (1999), S. 999-1006 
    Details
    ISSN: 1432-1955
    Keywords: Key wordsEchinococcus granulosus ; Praziquantel ; Metacestode ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The efficacy of praziquantel against the metacestode of Echinococcus granulosus was studied by means of in vitro incubations or in vivo experiments. The results of in vitro incubations indicated that the effectiveness of praziquantel was higher when the parasite material comprised cysts from cyst masses than in the case of intact cysts that retained their adventitial layer. Ultrastructural alterations in the germinal layer of collapsed cysts incubated in vitro were detected. The results obtained in mice after 4 months of treatment demonstrated no significant difference between the control and treated groups with regard to the number and wet weight of developed cysts. However, ultrastructural alterations were detected in the cyst tissue that were similar to those described in the in vitro experiment. In contrast, the effect of chemoprophylaxis on the number and the wet weight of developed cysts was extremely significant as compared with the control value, the efficacy being 99.41% and 98.32%, respectively. Moreover, ultrastructural observations of the cyst tissue revealed loss of its integrity, and no intact cyton was observed in the germinal layer of the developed cyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004360050672
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  • 61
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    Electronic Resource
    Morphology and ultrastructure of the anterior adhesive areas of the capsalid monogenean parasites Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanus carponotatus (Pisces: Lutjanidae) (1999)
    Springer
    Parasitology research 85 (1999), S. 399-408 
    Details
    ISSN: 1432-1955
    Keywords: Key words Monogenea ; Capsalidae ; Benedenia rohdei ; B. lutjani ; Ectoparasites ; Lutjanus carponotatus ; Glands ; Ultrastructure ; Adhesion ; Attachment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The anterior adhesive areas of Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanuscarponotatus at Heron Island, Australia, were studied using scanning and transmission electron microscopy. All specimens were fixed when detached from host tissue. Both monogenean species have two disc-like anteroventral attachment organs, each of which has an anterolateral adhesive area divided into three adjacent zones by tegument from the ventral surface of the attachment organ. A rod-shaped secretion and a smaller, roughly spherical secretion are associated with the anterior adhesive areas in both species; a third type of secretion occurs anteriorly but outside these adhesive areas. The electron-dense spherical secretory bodies released onto the anterior adhesive zones in these Benedenia spp. are of a single type and differ ultrastructurally from those previously reported in monogeneans living on teleost hosts. A correlation, therefore, between secretion morphology and host type is not supported. No relationship was found between parasite microhabitat and secretion morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004360050566
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  • 62
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    Electronic Resource
    Photochemistry of 9,10-Dicarbonyl-9,10-dihydroanthracene - A Source of 9,10-Dehydroanthracene? (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 57-60 
    Details
    ISSN: 1434-193X
    Keywords: Benzyne ; Dehydroanthracene ; Matrix isolation ; Photochemistry ; Bergman reaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -9,10-Didehydroanthracene (1) is an interesting derivative of p-benzyne that has been subject of several studies. In contrast to an earlier report, the photochemical decarbonylation of 9,10-dicarbonyl-9,10-dihydroanthracene (2) does not lead to 1 but rather to the ring-opened ene-diyne 4. The key intermediate for this reaction is keto carbene 7 which is formed by monodecarbonylation of 2. Carbene 7 is labile towards visible-light irradiation and easily looses the second CO molecule to give 4. Carbene 7 and diyne 4 are characterized by IR and UV/Vis spectra, the IR spectra are compared to calculations at the B3LYP/6-31G(d,p) level of theory.
    Additional Material: 2 Ill.
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  • 63
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    Electronic Resource
    Reversal Diastereofacial Selectivity in the n-Butyllithium Addition to O-Protected N-Trimethylsilylimines of (2S)-Lactal: Enthalpic versus Entropic Contributions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 61-65 
    Details
    ISSN: 1434-193X
    Keywords: Nucleophilic addition ; Solvent effect ; Reversal of diastereoselectivity ; Temperature effect ; Imines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Commonly observed, but rarely explored, is the possibility of modifying the diastereomeric excess (de%) by means of temperature. A complete reversal in the diastereofacial selectivity could be obtained whenever the diastereoisomers concerned are differentially favored by enthalpy and entropy. The enthalpic or entropic dominance of a diastereoisomer depends greatly on the reaction solvent used.
    Additional Material: 1 Ill.
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  • 64
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    Electronic Resource
    Syntheses of Donor-Acceptor-Substituted 2,6-Stellanes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 73-81 
    Details
    ISSN: 1434-193X
    Keywords: Donor-acceptor systems ; Cage compounds ; Stelladione ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A number of condensations could be carried out using tricyclo[3.3.0.03,7]octane-2-one (stellanone, 4) and tricyclo[3.3.0.03,7]octane-2,6-dione (2,6-stelladione, 5) as starting materials. The components for condensations were 2-trimethylsilyl-1,3-dithiane (6), 1,1-bis(trimethylsilyl)-1H-cyclopropa[b]naphthalene (7), its 3,6-dimethoxy-substituted analogue 8, fluorene (12), xanthene (13), diethyl malonate (14), and malononitrile (15). The condensation reactions with 5 yielded mono- and disubstituted products, among them were the donor-acceptor-substituted 2,6-stellanes 33-35. The structures of 18 (prepared from stellanone and fluorene), 19, 24, 27, 31 and 32 (synthesized by condensation of 2,6-stelladione and 2-trimethylsilyl-1,3-dithiane and malononitrile, respectively) were determined by X-ray crystallography.
    Additional Material: 1 Ill.
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  • 65
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    Electronic Resource
    Synthesis of ω-Nitro Acids and ω-Amino Acids by Ring Cleavage of α-Nitrocycloalkanones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 87-90 
    Details
    ISSN: 1434-193X
    Keywords: Water ; α-Nitrocycloalkanones ; ω-Nitro acids ; Surfactant ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The reaction of various α-nitrocycloalkanones 1 with aqueous 0.05 M NaOH, at 80 °C, in the presence of cetyltrimethylammonium chloride (CTACl) as a cationic surfactant, produces ω-nitro acids 2 in good yields. Reduction of the latter with HCOONH4/Pd-C, in methanol, at 80 °C affords ω-amino acids 3. The synthesis of methyl 9-oxodecanoate (8) is also reported.
    Additional Material: 2 Tab.
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  • 66
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    On the Selective O-Alkylation of Ambident Nucleophiles - The Synthesis of Thiohydroxamic Acid O-Esters by Phase-Transfer Reactions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 97-106 
    Details
    ISSN: 1434-193X
    Keywords: O-Alkylation ; Ambident nucleophile ; Thiazolethione ; Thiohydroxamic acid ; Phase-transfer reaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -O-Alkylation of cyclic thiohydroxamic acids 1 and 3-5 has been studied with a view to developing an efficient method for the synthesis of N-(alkoxy)pyridine-2(1H)-thiones and N-(alkoxy)thiazole-2(3H)-thiones. Four issues have been addressed and the following conclusions can be drawn: (i) Thiones 1 and 5 exist as O-H acids in the solid state. (ii) According to NMR investigations (1H, 13C), the thione structures should be largely retained in CDCl3, [D6]DMSO, and CD3OD solutions of acids 1, 3-5, as is also the case for pyridinethione salts 2a-h. (iii) O-Alkylation of pyridinethione salts occurs in competition with S-alkylation. Selective O-alkylation is however possible, if thiohydroxamate salts with large countercations, such as M = NBu4, are treated with hard alkylating reagents in polar aprotic media. (iv) As tetrabutylammonium thiohydroxamates, such as 2f, are highly useful in the synthesis of cyclic thiohydroxamic acid O-esters, we have developed an efficient protocol for the preparation of N-(alkoxy)pyridine-2(1H)-thiones directly from acid 1 using phase-transfer conditions (alkyl halide or sulfonic acid ester, CH3CN, K2CO3, Bu4NHSO4). This method has proved particularly successful for the synthesis of N-(alkoxy)thiazole-2(3H)-thiones 11, 20-28, which were obtained in yields of up to 87%.
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  • 67
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    Palladium(0)-Catalyzed Asymmetric Synthesis of 1,2,3,4-Tetrahydro-2-vinylquinoxalines (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 129-134 
    Details
    ISSN: 1434-193X
    Keywords: Tetrahydro-2-vinylquinoxaline ; Cyclization ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Reaction of (Z)-1,2-bis(methoxycarbonyloxy)but-2-ene (2) with various N,N-bis(arylsulfonyl)-o-phenylenediamines 1 was catalyzed by a palladium complex associated with chiral ligands to give optically active 1,4-bis(arylsulfonyl)-1,2,3,4-tetrahydro-2-vinylquinoxalines 3 with up to 62% ee. The use of (S)-MeOBIPHEP as the chiral ligand and N,N-bis(p-tolylsulfonyl)-o-phenylenediamine (1i) as the nucleophile led to the highest ee at 25 °C, regardless of the solvent used. The enantioselectivity of the cyclization is strongly affected by the nature of the substituents at the nitrogen atom.
    Additional Material: 4 Tab.
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  • 68
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    Stereoselective Synthesis of Enantiomerically Pure β-Fluoroalkyl γ-Butyrolactones by Sulfoxide-Directed Lactonization (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 111-115 
    Details
    ISSN: 1434-193X
    Keywords: Fluorine ; Lactones ; Annulation ; Ketene ; Sulfoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Enantiomerically pure α,α-dichloro β-fluoroalkyl γ-p-tolylthio γ-butyrolactones trans-6a-c have been obtained with excellent stereocontrol (〉 98:2) and enantiomeric purity (〉 98:2) by sulfoxide-directed lactonization (Marino's annu-lation reaction) of β-fluoroalkyl vinyl sulfoxides (R)-(E)-5a-c with dichloroketene. Highly chemoselective dechlorination and desulfurization reactions performed on trans-6c efficiently provided the β-chlorodifluoromethyl γ-butyrolactone (S)-8c, the absolute stereochemistry of which was determined by X-ray diffraction analysis of its γ-p-tolylthio precursor (2R,3S)-7c.
    Additional Material: 1 Ill.
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  • 69
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    Reaction of Nitrosobenzene with 4-Methoxy-N-methyleneaniline (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 141-143 
    Details
    ISSN: 1434-193X
    Keywords: Nitrosobenzene ; 4-Methoxy-N-methyleneaniline ; 1,3,5-Tris(4-methoxyphenyl)-1,3,5-triazinane ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A 1:1 adduct produced in the reaction of nitrosobenzene (2) with 1,3,5-tris(4-methoxyphenyl)-1,3,5-triazinane (3) has been shown by X-ray diffraction structure analysis to be the N′-(4-methoxyphenyl)-N-phenyl-N-oxyformamidinium species 5.
    Additional Material: 1 Ill.
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  • 70
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    A New Diastereoselective Synthesis of anti-α-Alkyl α-Hydroxy β-Amino Acids (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 155-161 
    Details
    ISSN: 1434-193X
    Keywords: Alkylation ; Oxazolines ; anti-α-Alkyl α-hydroxy β-amino acids ; Lithium dianion ; Penicillin G acylase ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -As part of an ongoing project concerning the synthesis of enantiomerically pure α-hydroxy β-amino acids, we have now developed a general strategy allowing the synthesis of anti-α-alkyl α-hydroxy β-amino acids. Our procedure involves the intermediate formation of trans-oxazolines, which are alkylated at C-5 with good to high diastereoselectivity and then hydrolysed under mildly acidic conditions, affording in quantitative yield the corresponding hydroxy amides. The starting (R)-3-amino-3-phenylpropanoic acid and (S)-3-aminobutanoic acid were obtained in enantiomerically pure form by selective enzymatic hydrolysis of the corresponding phenylacetylamides with penicillin G acylase.
    Additional Material: 3 Ill.
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  • 71
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    Palladium(0)-Catalyzed Reaction of Acidic Anilines with (Z)-2-Butene-1,4-diyl Dicarbonate - Preparation of N-Aryl-4-vinyloxazolidin-2-ones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 181-186 
    Details
    ISSN: 1434-193X
    Keywords: Palladium catalysis ; Homogeneous catalysis ; Anilines ; Alkylation ; Oxazolidinones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Palladium-catalyzed reaction of acidic anilines with (Z)-2-butene-1,4-diyl dicarbonate affords N-aryl-4-vinyloxazolidin-2-ones. The success of the reaction depends on the acidity of the aniline and requires in situ conversion of the dicarbonate into carbamate carbonate by nucleophilic attack of the aniline conjugate base followed by palladium-catalyzed intramolecular cyclization.
    Additional Material: 1 Tab.
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  • 72
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    Substituent Effects on the Vinylcyclopropane-Cyclopentene Rearrangement - A Theoretical Study by Restricted and Unrestricted Density Functional Theory (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 215-220 
    Details
    ISSN: 1434-193X
    Keywords: Density functional calculations ; Vinylcyclopropane-cyclopentene rearrangement ; [1,3]-Sigmatropic shift ; Biradical-like transition structure ; Substituent effects ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The effect of donor substitution by the hydroxy group and of acceptor substitution by the cyano group on the activation energies of the vinylcyclopropane-cyclopentene rearrangement was calculated by the spin-restricted RB3LYP/6-31G* method for reactant structures and by the spin-unrestricted UB3LYP/6-31G* method for transition structures. The activation energies of the rearrangement of hydroxy- and cyano-substituted vinylcyclopropanes are very similar for substitution in the same position. In agreement with earlier findings the substituent effects on the activation energies are closely connected with the radical stabilizing properties of the substituents. As indicated by singlet/triplet splitting energies, the transition structures are essentially biradicaloid. In spite of spin pairing in the transition structure the substituent effects on bond lengths and on stabilization energies are very similar to those of the free radicals corresponding to the two radical substructures. Thus, the transition structures may be considered, in good approximation, as structures consisting of two weakly interacting radicals.Supporting information for this article is available on the WWW under -http://www.wileY-Vch.de/contents/jc_2046/1999/98349_s.pdf or from the author.
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  • 73
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    Syntheses and Reactions of 1-Amino-2,2-dialkylcyclopropane-1-carbonitriles and -carboxamides - Potential Precursors of ACC Derivatives (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 239-250 
    Details
    ISSN: 1434-193X
    Keywords: Cyclopropanes ; Rearrangements ; Cyanohydrins ; Schiff bases ; Small ring systems ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The direct cyclization of 2-amino-4-chloro-3,3-dimethylbutanenitrile with potassium tert-butoxide in THF afforded 1-amino-2,2-dimethylcyclopropane-1-carbonitrile and a dimerization product. Various new cis- and trans-1-(tert-butylamino)-2-benzyl-2-methylcyclopropane-carbonitriles and© the corresponding cyclopropanecarboxamides have been synthesized, with focus on the isolation of the pure stereoisomeric cyclopropanecarboxamides. The relative configuration of the stereoisomers was established by X-ray crystallographic analysis of one of the model compounds. A new route to the latter functionalized cyclopropanes was developed by reaction of 1-methoxycyclopropylamines with potassium cyanide. Some remarkable rearrangements of 1-aminocyclopropane-1-carbonitriles into azetidine and oxazine derivatives via Favorskii-derived intermediates are reported. Various aspects of the chemistry of geminally functionalized cyclopropanes are discussed.
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    Regio- and Stereoselective Synthesis of Vinylallenes by 1,5-(SN′′)-Substitution of Enyne Acetates and Oxiranes with Organocuprates (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 267-275 
    Details
    ISSN: 1434-193X
    Keywords: Vinylallenes ; Organocuprates ; Substitution ; Stereoselective synthesis ; Copper catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Enyne acetates 2, 4, 6, and 8, as well as enyne oxiranes 10, with different substitution patterns react with organocuprates regioselectively under 1,5-(SN2′′)-substitution to provide vinylallenes 11 and 12. With lithium dimethylcuprate, reduced vinylallenes originating from a (formal) transfer of a hydride ion to the substrate are formed in some cases. The products are usually obtained as mixtures of (E/Z)isomers; however, pure (E)-vinylallenes are formed occasionally. The 1,5-substitutions can also be carried out with catalytic amounts of copper reagents. The reaction of chiral enyne acetate (S)-2a with tBu2CuLi · LiCN proceeds enantioselectively, so that this transformation constitutes a new case of remote stereocontrol.
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    Reactions of the Hydrofluoroborate Salts of Open-Chain Analogues of Reissert Compounds with Some α,β-Ethylenic Esters (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 297-303 
    Details
    ISSN: 1434-193X
    Keywords: Nitrogen heterocycles ; Open-chain analogue of Reissert compound ; Hydrofluoroborate salts ; α,β-Ethylenic esters ; 1,3-Dipolar cycloaddition ; Azomethine ylide ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The reaction of the hydrofluoroborate salt of an open-chain analogue of a Reissert compound with some α,β-ethylenic esters does not give a [4 + 2] cycloadduct, as previously described in the case of ethyl acrylate. The reaction starts with a 1,3-dipolar cycloaddition of a münchnone imine 5c, d. The [3 + 2] cycloadducts 13 evolve via a rearrangement-condensation sequence to give a substituted 2-pyridone derivative 18 or 19. The proposed mechanism has been verified by the isolation and structural X-ray analysis of some compounds of the reaction sequence.
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    EPC-Synthesis of β-Amino Acid Derivatives through Lithiated Hydropyrimidines (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 335-360 
    Details
    ISSN: 1434-193X
    Keywords: 2-tert-Butylhydropyrimidinones ; 3-Aminocarboxylic acid derivatives ; Cyclic imino esters ; Lithium enaminates ; Alkylations ; β-Amino acids ; Asymmetric synthesis ; Kinetic resolution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Racemic and enantiopure 2-tert-butyltetrahydropyrimidinones (from pivalaldehyde and 3-aminocarboxylic acids) are converted to Alloc-, Boc-, and Z-protected cyclic imino esters (7-10, Schemes 2-4). These are deprotonated to Li enaminates (K, L). Reactions with electrophiles (prim., sec. alkyl, allyl, benzyl, propargyl halides, aldehydes, imines, enoates) give good yields and are highly diastereoselective (products 11-42, Schemes 5-10). A two-step cleavage (removal of protecting group and hydrolysis) under very mild conditions converts the heterocyclic products to α-branched β-amino acid methyl esters (43-61, Schemes 11-13). The structure of the products is determined by NMR spectroscopy (Figure 1), by chemical correlation (Scheme 14), and by X-ray analysis (Figure 2, 3, 7, Table 1). A structure of the Li enaminates is proposed (Figure 4). Mechanistic models are derived for the reactions occurring with formation of two stereogenic centers with relative topicity like (Figures 5, 6).
    Additional Material: 7 Ill.
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    A Unified Synthetic Strategy for the Indolopyridine Alkaloid Group (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 373-378 
    Details
    ISSN: 1434-193X
    Keywords: Alkaloids ; Cross-coupling ; N-Heterocycles ; Palladium ; Synthesis design ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Thermal or acetyl chloride induced cyclization of bromoenamide 10 affords the pentacyclic derivative 12 with high yield and regioselectivity. From this common synthetic intermediate, palladium-catalyzed reactions allow the total synthesis of indolopyridine alkaloids 1-6.Supporting information for this article is available on the WWW under -http://www.wileY-Vch.de/contents/jc_2046/1999/98332_s.pdf or from the author.
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    Conformational Preferences of Peptides Containing Reverse-Turn Mimetic Bicyclic Lactams: Inverse γ-Turns versus Type-II′ β-Turns - Insights into β-Hairpin Stability (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 389-400 
    Details
    ISSN: 1434-193X
    Keywords: Reverse-turn mimics ; γ-Turns ; β-Turns ; β-Hairpins ; NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The solid-phase synthesis and characterization of a series of peptides (3-9), containing reverse-turn mimetic bicyclic lactams (1a, 1b), was reported in the preceding paper. The bicyclic lactams (1a, 1b) possess high structural similarity to the two central residues of a β-turn. The conformational preferences of the constrained peptides have been investigated by NMR spectroscopy and IR spectroscopy. Our experimental results have been complemented by computer modelling studies and show that the constrained peptides (3-9) form an inverse γ-turn or a type-II′ β-turn through intramolecular hydrogen bonding, depending on the nature of the reverse-turn mimic. In N-acetylated tetrapeptide mimics incorporating the two different bicyclic lactams (a series and b series), H5 is available for either a γ-turn (7-membered ring with the carbonyl group of the bicyclic lactam) or a β-turn (10-membered ring with the carbonyl group of residue 2), as shown in Figures 7 and 9. The a series incorporating the (5,7)-bicyclic lactam predominantly induces the γ-turn conformation, while the b series incorporating the (5,6)-bicyclic lactam can promote either a γ-turn or a β-turn conformation, with the β-turn usually being preferred and with varying degrees of β-hairpin formation.
    Additional Material: 10 Ill.
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    Deprotonation of Oxazolinyloxiranes: Formation of Substituted Acyloxiranes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 409-417 
    Details
    ISSN: 1434-193X
    Keywords: Deprotonation ; Oxiranyloxazolines ; Oxazolinyloxiranyllithium compounds ; Oxazolidines ; Acyloxiranes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Deprotonation of oxazolinyloxiranes 1a, 1h, and 1k with sBuLi/TMEDA at -100 °C in Et2O furnishes oxazolinyloxiranyllithium compounds[1]1b, 1i, and 1l which are stable at low temperature and can be trapped with electrophiles to give substituted oxiranes 1c-1g and 1j. The reaction of 1b with aldehydes produced diastereomers syn (2a-d) and anti (3a-d). Oxiranyllithium 1i from trans-1-(4,4-dimethyl-2-oxazolinyl)-2-p-tolylepoxyethane (1h) was found to be configurationally stable while oxiranyllithium 1l, generated from the cis isomer 1k, was not. Oxazolinylepoxides 1d, 1j, and 1m could be deblocked to acyloxiranes 5a-e through oxazolidines 4a-e.
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  • 80
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    N-Substituted 1-Aminoindoles from Electrogenerated N-Substituted 2-(ortho-Nitrosophenyl)ethylamines (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 419-430 
    Details
    ISSN: 1434-193X
    Keywords: Electrochemistry ; Electrosynthesis ; Nitrosobenzenes ; Nitrogen heterocycles ; 1-Aminoindoles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -An electrochemical methodology offering efficient access to N-alkyl- and N-aryl-substituted 1-aminoindoles has been developed. N-Substituted 2-(ortho-nitrosophenyl)ethylamines, electrogenerated in a “redox” flow cell, undergo intramolecular cyclization to hydrocinnoline-type intermediates. Under slightly basic conditions, these undergo spontaneous ring-contraction to produce the N-substituted heterocycles in good yields. The reactions have been studied in slightly acidic and slightly basic aqueous alcoholic media.
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    Synthesis of Enantiopure β- and γ-Amino Alcohols from Homochiral α- and β-Aminoacylsilanes as Stable Synthetic Equivalents of α- and β-Amino Aldehydes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 437-445 
    Details
    ISSN: 1434-193X
    Keywords: Aminoacylsilanes ; Amino aldehydes ; Amino alcohols ; Allylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A practical route is described for the synthesis of enantiopure β- and γ-amino alcohols with two stereocenters, starting from homochiral α- (1 and 5) and β- (13 and 16) -aminoacylsilanes, and involving stereoselective addition of allylmetal compounds and subsequent stereospecific protiodesilylation of the adducts. The degree of diastereoselectivity achieved in the nucleophilic addition step depends on both the nitrogen-protecting group and the reagents used. Diastereomeric excess (de) values equal to or higher than 98% were obtained in the TiCl4-promoted allylation of the N-Pht-aminoacylsilanes 1 and 13 and of the N-Ts-aminoacylsilane 5 with allyltrimethylsilane. Lower de values were obtained in the Sc(OTf)3-catalyzed allylation of 5 with tetraallyltin and in the additions of both allyltrimethylsilane and tetraallyltin to the N-Ts-β-aminoacylsilane 16. Protiodesilylation of the adducts, leading to the β- and γ-amino alcohols, was accomplished with TBAF, except in the case of the adducts obtained from 5. For these, a preliminary removal of the tosyl group was necessary, which was accomplished with simultaneous desilylation by treatment with Na in liquid ammonia.Supporting information for this article is available on the WWW under -http://www.wileY-Vch.de/contents/jc_2046/1999/98342_s.pdf or from the author.
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    Diastereoselective Intramolecular meta Photocycloaddition of Side-Chain-Substituted 5-(2-Methoxyphenyl)pent-1-enes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 463-470 
    Details
    ISSN: 1434-193X
    Keywords: meta Photocycloaddition ; Photochemistry ; Steric hindrance ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Irradiation of a series of 5-(2-methoxyphenyl)pent-1-enes substituted with a hydroxy or trimethylsilyloxy group at the α-, β-, or γ-position of the side-chain yields in all cases meta photocycloadducts, in which the configuration at the substituted carbon atom is mainly endo. This indicates that the diastereoselectivity originates from minimization of steric interactions between the side-chain substituent and the ortho-methoxy group at the arene unit. Hydrogen bonding does not seem to be involved. The introduction of the side-chain substituents also influences the regioselectivity of the addition: The linear to angular adduct ratios are significantly increased compared to the case of the parent compound.
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    5-Aza-7-deaza-2′-deoxyguanosine: Oligonucleotide Duplexes with Novel Base Pairs, Parallel Chain Orientation and Protonation Sites in the Core of a Double Helix (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 485-496 
    Details
    ISSN: 1434-193X
    Keywords: 5-Aza-7-deaza-2′-deoxyguanosine ; Oligonucleotides ; Parallel DNA ; Protonated base pairs ; Tm values ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Oligonucleotides containing 5-aza-7-deaza-2′-deoxyguanosine (1) were synthesized. Solid-phase synthesis was performed with the phosphonate 15 or the phosphoramidite 5. The amino-unprotected phosphonate 4 was also employed. Hybridization studies of oligonucleotides containing 1 resulted in new base pairs leading to duplexes with parallel (ps) or antiparallel (aps) chain orientation. Among those with parallel chains a stable “purine-purine” base pair was observed between 5-aza-7-deazaguanine and guanine or 7-deazaguanine. Antiparallel stranded duplexes are formed when 5-aza-7-deazaguanine pairs with cytosine. This base pair has only two hydrogen bonds under neutral conditions but is stabilized by a third one in acidic medium. A new base pair is also detected between the base of 1 and isoguanine (neutral medium).
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    Polar and Steric Substituent Effects in 5-exo-trig Cyclizations of 1-Aryl-4-penten-1-oxyl Radicals (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 523-523 
    Details
    ISSN: 1434-193X
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -By mistake wrong concentrations were given in the footnote of Table 1 and in the Discussion. Instead of c0 = 1.2 M read c0 = 0.12 M if 2-naphthalenethiol was used as hydrogen donor and instead of c0 = 1.8 M read c0 = 0.18 M if Bu3SnH was used to trap photoproducts. In Table 2 relative rate constants of radical 2d refer to radical 2e and vice versa as correctly stated in the Discussion. In the Experimental Section (Iodocyclization) read 2.25 g (8.86 mmol) of iodine instead of 2.25 g (1.10 mmol) of iodine.
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    Arylboron Compounds as Acid Catalysts in Organic Synthetic Transformations (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 527-538 
    Details
    ISSN: 1434-193X
    Keywords: Tris(pentafluorophenyl)borane ; Diarylborinic acid ; Arylboronic acid ; Chiral arylboron catalyst ; Lewis acid ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Arylboron compounds, ArnB(OH)3-n (n = 1-3), bearing electron-withdrawing aromatic groups such as triarylboranes, diarylborinic acids, and arylboronic acids represent a new class of air-stable and water-tolerant Lewis acid or Brønsted acid catalysts in organic synthesis. In particular, while tris(pentafluorophenyl)borane has primarily been used as a co-catalyst in metallocene-mediated olefin polymerization, its potential as a Lewis acid catalyst for organic transformation is now much more extensive. Diarylborinic acids and arylboronic acids have shown themselves to be powerful tools in the design of chiral boron catalysts. This article provides a comprehensive summary of the organic transformations catalyzed by arylboron compounds as acids.
    Additional Material: 2 Ill.
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  • 86
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    Electronic Resource
    2D-NMR-Guided Constitutional Analysis of Organic Compounds Employing the Computer Program COCON[#] (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 573-577 
    Details
    ISSN: 1434-193X
    Keywords: Structure elucidation ; Constitutional analysis ; Natural products ; HMBC ; Computational chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The computer program COCON is introduced as a tool for the comprehensive structure elucidation of unknown organic compounds. In particular, structural proposals made on the basis of the molecular formula and of 2D-NMR experiments can be analyzed for the existence of alternative constitutions being in agreement with the same data set. The computational speed grounds on the evaluation of ambiguous long-range connectivity information during the process of structure generation. The data set experimentally obtained for the marine natural product oroidin (1) was selected, because proton-poor compounds usually cause uncertainties in NMR-based structure determinations. The calculation results encourage to move from the experience-based analysis of NMR chemical shifts or of MS fragmentations to the automated evaluation of routinely available connectivity information.Supporting information for this article is available on the WWW under -http://www.wileY-Vch.de/contents/jc_2046/1999/98241_s.pdf or from the author.
    Additional Material: 6 Ill.
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  • 87
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    Electronic Resource
    3,5-Dimesityl-1,2,4-oxadiphosphole - Synthesis and Reactivity of a Novel Heterocycle (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 587-595 
    Details
    ISSN: 1434-193X
    Keywords: Phosphaalkenes ; Heterodiphospholes ; Cycloadditions ; Phosphaalkyne cyclooligomers ; Phosphorus-carbon cage compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The first synthesis of a 1,2,4-oxadiphosphole 6 has been achieved by vacuum thermolysis of mesitylphosphaalkene 5. The novel heterocycle 6 exhibits an enormous potential for cycloaddition reactions, which predominantly proceed selectively at low temperatures. Compound 6 undergoes addition with two equivalents of phosphaalkynes 10 by a [4+2] cycloaddition/homo Diels-Alder reaction sequence to form novel oxatetraphosphadeltacyclenes 12 and 13. Tetrachloro-o-benzoquinone (14) undergoes a selective [4+1] cycloaddition with 12 and 13 leading to the spirocyclic products 15 and 16 containing λ5-phosphorus atoms. Treatment of the oxadiphosphole 6 with dimethyl acetylenedicarboxylate (17) provides the first access to a 1,2-oxaphosphole 18, which is formed after an initial [4+2] cycloaddition followed by a retro Diels-Alder reaction. An unexpected reaction of 6 is observed with tri-tert-butylazete (20) furnishing a new polycyclic system (→ 21).
    Additional Material: 4 Ill.
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  • 88
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    Synthesis of 1β-Methylcarbapenem Antibiotic Precursors by Cyclization Using π-Allylpalladium Complexes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 621-626 
    Details
    ISSN: 1434-193X
    Keywords: 1β-Methylcarbapenems ; Palladium ; Ruthenium ; Catalysis ; Cyclizations ; Stereoselective hydrogenation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -An efficient diastereoselective multi-step synthesis of bicyclic 1β-methylcarbapenem antibiotic precursors has been developed, starting from the commercially available 4-acetoxyazetidin-2-one 4. Chiral ruthenium catalysts are used in the hydrogenation step to control the β-stereochemistry at the 1-position, and a π-allylpalladium ring-closure strategy is used to form the functionalized carbapenem skeleton.
    Additional Material: 1 Tab.
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  • 89
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    Oligo-2,6-naphthylenevinylenes - New Building Blocks for the Preparation of Photoluminescent Polymeric Materials (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 643-651 
    Details
    ISSN: 1434-193X
    Keywords: Oligomers ; Synthesis design ; Substituent effects ; Luminescence ; Cyclic voltammetry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Synthetic strategies towards appropriate symmetric and unsymmetric functionalization of the naphthalene ring are presented. By means of Knoevenagel and Wittig condensation reactions new fluorescent, differently functionalized oligo(2,6-naphthylenevinylene)s have been synthesized, the presence of terminal aldehyde or bromine substitution opening the way to the incorporation of the fluorescent trimers in a variety of polymeric materials. The effect of substituting the phenylene ring by the more bulky dialkoxynaphthalene system in arylenevinylene-type materials is studied from the structural point of view and the possibility to tune the emission color and the electron affinity through the introduction of naphthylenevinylene and cyano-substituted naphthylenevinylene units is also investigated.
    Additional Material: 4 Ill.
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  • 90
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    New Type of Skipped Oligoaziridines: Synthesis of New Fatty AcidDerivatives Containing Aziridine Functions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 661-664 
    Details
    ISSN: 1434-193X
    Keywords: Aziridines ; N-Heterocycles ; Fatty acids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The first successful preparation of the aziridines methyl cis-9,10;cis-12,13-diepiminooctadecanoate (3) derived from linoleic acid, and methyl cis-9,10;cis-12,13;cis-15,16-triepiminooctadecanoate (6) derived from linolenic acid, is reported. Remarkably, the bis- and trisaziridine were obtained in a reaction sequence that consists of only two steps, using technically pure methyl esters of epoxidized sunflower and linseed oil. The conversion of methyl 9,10;12,13-diepoxyoctadecanoate (1), with sodium azide and ammonium chloride in ethanol in the presence of water, yielded the new diazidodihydroxy compound methyl 9(10),12(13)-diazido-10(9),13(12)-dihydroxyoctadecanoate (2) in the first step. 2 was obtained as a regioisomeric mixture. The reaction of 2 with triphenylphosphane led to the bisaziridine 3. The analogous conversion of methyl 9,10;12,13;15,16-triepoxyoctadecanoate (4), via the new triazidotrihydroxy compound methyl 9(10),12(13),15(16)-triazido-10(9),13(12),16(15)-trihydroxyoctadecanoate (5), afforded trisaziridine 6.
    Additional Material: 1 Tab.
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  • 91
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    Novel Ligands for the Separation of Trivalent Lanthanides and Actinides - Tetrakis(phosphane sulfide) and -(phosphinic acid) Cavitands (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 665-674 
    Details
    ISSN: 1434-193X
    Keywords: Cavitands ; Nuclear waste ; Actinide/lanthanide separation ; Solvent extraction ; Sulfur atoms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Cavitands with phosphane sulfide moieties 4 and 8a,b were prepared in good yields from their phosphane oxide analogues, as more stable alternatives for the dithiophosphinic acids used at present. The cavitands 7a and 7b with flexible butoxyphosphane oxide ligating sites are more efficient than cavitand 3 having rigid methylphosphane oxide groups as was studied with EuIII picrate extractions. Due to the absence of an ionic functionality in the phosphane sulfides 4 and 8a,b AmIII and EuIII are not extracted, not even in the presence of synergents (e.g. TBP, TOPO, HDNNS). Cavitand 10 with phosphinic acid groups efficiently extracts EuIII in 1:1 or 2:1 complexes, depending on the metal-to-ligand concentration ratio (extraction constants Kex1 = 3.9·10-5M2 and Kex2 = 1.9·102M, respectively). Furthermore, in the case of 10 EuIII is preferentially extracted over AmIII with a separation factor SEu/Am up to 5.
    Additional Material: 5 Ill.
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  • 92
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    Preparation of 2,3,5-Tri-O-benzyl-4-thio-L-arabino-furanosides and the Corresponding 4′-Thionucleoside Analogues (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 691-696 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; 4-Thiofuranosides ; Nucleosides ; Reaction mechanisms ; NOE measurements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -1-O-Acetyl-2,3,5-tri-O-benzyl-4-thio-L-arabino-furanose (9) has been prepared from D-xylose via the 1,4-dithio-L-arabino-furanoside 8. The crucial step of the reaction, i.e. the intramolecular cyclization of the open-chain dithioacetal 5, has been achieved in a yield of 90% by applying tetrabutylammonium iodide as promoter. Reaction of 9 with bis(trimethylsilyl)uracil or -thymine led to the benzyl derivatives 12 and 13 from which the deprotected 4′-thionucleoside analogues 14 and 15 have been prepared by debenzylation with boron tribromide.
    Additional Material: 1 Ill.
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  • 93
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    100 Years of Baeyer-Villiger Oxidations (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 737-750 
    Details
    ISSN: 1434-193X
    Keywords: Baeyer-Villiger oxidation ; Ketones ; Monopersulfate ; Peracids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -In the present review, we report the discovery of the formation of esters and lactones by oxidation of ketones with a peroxide derivative, namely the Baeyer-Villiger reaction. This reaction was first reported by Adolf von Baeyer and Victor Villiger a century ago in 1899, just one year after the oxidant they used (KHSO5) has been described. Furthermore, Baeyer and Villiger established the composition of this new inorganic peroxide and showed that its instability was the reason of a controversy between several European chemists between 1878 and 1893. For the first 50 years the mechanism of the Baeyer-Villiger reaction was a matter of debate. A side product, 1,2,4,5-tetraoxocyclohexane, was ruled out as an intermediate in the ester formation by Dilthey. Criegee postulated a nucleophilic attack of the oxidant on the carbonyl group. This mechanism was confirmed by von E. Doering by a labeling experiment with [18O]benzophenone. The rearrangement step occurs with retention of the stereochemistry at the migrating center. The competitive migration and the rate-determining step are also discussed in this review.
    Additional Material: 4 Ill.
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  • 94
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    Transferase Activity of a β-Glycosidase from Thermus thermophilus: Specificities and Limits - Application to the Synthesis of β-[1→3]-Disaccharides (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 757-763 
    Details
    ISSN: 1434-193X
    Keywords: Transglycosylation ; Glycosidases ; Thermus thermophilus ; Carbohydrates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The aim of this paper is to test the ability of a β-glycosidase from Thermus thermophilus to catalyse transglycosylation reactions in the presence of nitrophenyl glycosides as donors and other monosaccharides as acceptors. Our results show that this enzyme is able to induce such reactions either with nitrophenylgalactosides, -glucosides and -fucosides. With the two former donors, the autocondensation of the donor, which thus acts also as an acceptor, is faster than the transglycosylation with other acceptors. Furthermore, as the regioselectivity of the reactions is mainly of the β-[1→3] type, good yields are obtained for the synthesis of 2-nitrophenyl-β-D-galactopyranosyl-[1→3]-β-D-galactopyranoside and 2-nitrophenyl-β-D-glucopyranosyl-[1→3]-β-D-glucopyranoside. Conversely, in the presence of p-nitrophenylfucoside, the autocondensation is very limited, and with methyl-α-D-galactoside as an acceptor, the regioselectivity is mainly of the β-[1→6]-type resulting in the synthesis of methyl-β-D-fucopyranosyl-[1→6]-α-D-galactopyranoside.
    Additional Material: 7 Ill.
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  • 95
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    Reduction of Acetylenic Compounds to (E)-Olefins by Alkali Metals - An Investigation of the Scope (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 775-779 
    Details
    ISSN: 1434-193X
    Keywords: Monoynes ; Polyynes ; Alkali metals ; Liquid NH3 ; Hexamethylphosphoric triamide ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Efficient procedures have been developed for the stereospecific reduction by alkali metals of disubstituted acetylenes with long carbon chains. Acetylenes containing two or more (isolated) triple bonds are reduced considerably more easily than are monoynes.
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  • 96
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    Synthesis of Enantiopure o-Hydroxybenzylamines by Stereoselective Reduction of 2-Imidoylphenols: Application in the Catalytic Enantioselective Addition of Diethylzinc to Aldehydes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 805-811 
    Details
    ISSN: 1434-193X
    Keywords: Aminophenols /Asymmetric synthesis ; C-C coupling ; Reductions ; Conformation analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Enantiopure o-hydroxybenzylamines 2a-i were synthesized by diastereoselective reduction of the 2-imidoylphenols (R)-1a-i. Conformational analysis enabled the assignment of the absolute configurations of compounds 2a-i. The accessible o-hydroxybenzylamine (R,R)-2h serves as an effective catalyst precursor for highly enantioselective addition of diethylzinc to aliphatic and aromatic aldehydes. This pathway represents a practical and operationally very simple methodology for the enantioselective synthesis of both the enantiomers of secondary alcohols 7a-f.
    Additional Material: 4 Ill.
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  • 97
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    Cyclialkylation of Arylalkyl Epoxides with Solid Acid Catalysts (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 837-846 
    Details
    ISSN: 1434-193X
    Keywords: Friedel-Crafts reaction ; Hydroxyalkylation ; Aromatics ; Epoxides ; Zeolites ; Clays ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Solid acids, such as zeolites and clays, catalyse the intramolecular hydroxyalkylation (cyclialkylation) of several arylalkyl epoxides in moderate to excellent conversions and selectivities. The use of solid acids in these cyclialkylations provides a cleaner, better alternative to conventional Lewis and Brønsted acids, enabling a more facile workup of reaction mixtures and, in several cases, better selectivities.
    Additional Material: 3 Ill.
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  • 98
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    Phosphorylating Power of Red Phosphorus towards Aldehydes in Basic and in Acidic Media (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 861-868 
    Details
    ISSN: 1434-193X
    Keywords: Red phosphorus ; Phosphane PH3 ; Phosphorylations ; Ultrasound irradiation ; Redox chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The reactivity of red phosphorus towards aldehydes was investigated under basic and acidic media. It was demonstrated that the real phosphorylating agent involved in the reaction was phosphane (PH3) in basic media, and hypophosphorous acid (H3PO2) in acidic media. A convenient one-pot synthesis of (α-hydroxyalkyl)phosphinic acids from red phosphorus and aldehydes in basic media was realized under sonication. The same reaction under acidic media in the presence of hydriodic acid led to the corresponding phosphonic acids. The (α-hydroxyalkyl)phosphinic acids were readily prepared under sonication from hypophosphorous acid and aldehydes in the presence of catalytic amounts of hydrochloric acid. The mechanism of the addition reaction of PH3 to benzaldehyde was elucidated and shows the complexity of the reaction as a function of the experimental conditions.
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  • 99
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    A New Approach to Erythrinanes through Pummerer-Type Cyclization (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 909-915 
    Details
    ISSN: 1434-193X
    Keywords: Erythrina alkaloids ; Nitrogen heterocycles ; Nitro aldol reaction ; Michael addition ; Pummerer reaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A successful new strategy for the synthesis of erythrinanes is reported. (Nitromethyl)arene derivative 16 was condensed with aldehyde 17 to give nitro aldol 19. After removal of the hydroxy group, the subunits 26a,b, containing the erythrinane rings A and D, were formed by intramolecular Michael addition. Reduction of the nitro function, followed by cyclization of the resulting amino group with the appended acetate group afforded the bicyclic lactams 29a,b, bearing an angular aryl group. Two-carbon elongation at the nitrogen atoms of 29a and 29b by means of hetero Michael addition of methyl phenyl sulfoxide, followed by Pummerer-type cyclization, gave cis- and trans-11-phenylthioerythrinan-8-ones 35a and 35b, respectively. Reductive desulfurization at C-11 furnished the desired erythrinan-8-ones 39a and 39b in 8 steps from 16.
    Additional Material: 1 Ill.
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  • 100
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    Synthesis, X-ray Structure Analysis and Topochemical Photopolymerization of Substituted 1,6-Bis(2,5-dimethoxyphenyl)hexa-2,4-diynes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 917-922 
    Details
    ISSN: 1434-193X
    Keywords: Crystal engineering ; Diynes ; Photochemistry ; Solid-state chemistry ; Polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The 1,6-bis(2,5-dimethoxyphenyl)hexa-2,4-diynes 4a-c were obtained from the corresponding 2,5-dimethoxybenzenes 1 by bromination followed by a copper-catalyzed Grignard reaction with 3-bromoprop-1-yne. Catalyzed coupling of the resulting 3-(2,5-dimethoxyphenyl)prop-1-ynes 3 under Hay conditions gave the hexa-2,4-diynes 4a-c in good yields. The molecular structures of the diynes 4a and 4b were determined by X-ray diffraction analysis. In each crystal structure, an unusual 1,6-synperiplanar conformation of the hexa-2,4-diyne unit is observed, with the 1,6-diphenyl substituents arranged in a coplanar orientation. According to the crystal structure data obtained, irradiation of diynes 4a and 4b afforded the deeply-colored, highly-ordered polymers 5a and 5b under topochemical control. Oxidation of 4a and 4b with cerium(IV) ammonium nitrate gave the corresponding 1,6-bis(2,5-dimethoxyphenyl)hexa-2,4-diyne-1,6-diones 6a and 6b.
    Additional Material: 5 Ill.
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