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  • 2005-2009
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  • 1
    Electronic Resource
    Electronic Resource
    Rhabdoid tumours of the central nervous system (1993)
    Springer
    Virchows Archiv 422 (1993), S. 81-85 
    Details
    ISSN: 1432-2307
    Keywords: Rhabdoid tumour ; Central nervous system ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three cases of rhabdoid tumour of the central nervous system arising in a supratentorial location are reported. The patients were 18, 14, and 7 years old. All three tumours showed a common morphology. The neoplastic cells were usually globoid with round nuclei and prominent nucleoli and large acidophilic, cytoplasmic inclusions were present in many of them. These inclusions showed strong immunoreactivity for vimentin, weak immunoreactivity for epithelial membrane antigen and focal immunoreactivity for cytokeratins. Ultrastructurally they were made up of whorls of intermediate filaments, 8–10 nm in thickness. Rhabdoid tumours of the central nervous system, whatever the cell of origin, appear to be an independent entity with identifiable histology and aggressive behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605137
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  • 2
    Electronic Resource
    Electronic Resource
    Localized amyloidosis in squamous cell carcinoma of uterine cervix: Electron microscopic features of nodular and star-like amyloid deposits (1993)
    Springer
    Virchows Archiv 422 (1993), S. 225-231 
    Details
    ISSN: 1432-2307
    Keywords: Amyloid ; Amyloidosis ; Squamous cell carcinoma ; Keratin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An ultrastructural study of amyloid deposits in four cases of squamous cell carcinoma of uterine cervix was performed. The amyloid deposits reacted with anti-keratin antiserum on frozen sections. Amyloid deposits showed nodular (4 cases) and star-like forms (3 cases). Nodular amyloid deposits were composed of slightly whorled fibrils, measuring 7–10 nm in width. Some of them contained cellular debris and thicker, more electron-dense filaments than amyloid fibrils. In three cases, filamentous tumour cells and filamentous masses were observed together with amyloid. Star-like amyloid deposits were composed of bundles of straight amyloid fibrils. Some of the tumour cells in contact with star-like amyloid deposits had deep cytoplasmic invaginations, where closely packed amyloid fibrils were arrayed in parallel fasion. In addition, a few tumour cells had membrane-bound amyloid fibrils in the cytoplasm. It is suggested that nodular amyloid deposits are derived from the tumour cells through filamentous degeneration. Amyloid fibrils in star-like amyloid deposits are thought to be formed within the cytoplasm or in the vicinity of invaginated cytoplasmic membranes of the tumour cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01621806
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  • 3
    Electronic Resource
    Electronic Resource
    Widening of capillary neck and alteration of extracellular matrix ultrastructure in diabetic rat glomerulus as revealed by computer morphometry and improved tissue processing (1993)
    Springer
    Virchows Archiv 423 (1993), S. 121-129 
    Details
    ISSN: 1432-2307
    Keywords: Ultrastructure ; Morphometry ; Diabetic nephropathy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological and morphometric studies of glomeruli were carried out in streptozotocin-induced diabetic rats using improved tissue processing and computerized morphometry. Increased mesangial matrix, occupying the enlarged diabetic mesangium, contained an abundance of dark granular material in addition to the microfibrils which were usually found in the control glomeruli. In the diabetic glomeruli, the lamina densa was thick and heterogeneous showing a dense layer both on its epithelial and endothelial aspects, and the lamina rara externa contained more fibrils than in control rats. Detailed estimation of the absolute values of the various compartments of the diabetic glomeruli by using perfusion-flxed materials and a computer-assisted digitizer revealed that the volume and surface area of the mesangium were increased more extensively than those of the capillary; the enlargement of the mesangial-capillary interface area was the most pronounced among the morphometric changes of the diabetic glomeruli; and that the moderate increase in capillary volume was associated with an increased radius. Our quantitative results showed that capillaries in the diabetic glomeruli had an extensively wider neck which may be the first sign of structural damage to the glomerular tuft.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01606586
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  • 4
    Electronic Resource
    Electronic Resource
    Altered intestinal development after jejunal ligation in fetal sheep (1993)
    Springer
    Virchows Archiv 423 (1993), S. 45-50 
    Details
    ISSN: 1432-2307
    Keywords: Fetus ; Small intestine ; Ultrastructure ; Intestinal atresia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Experimental obstruction of the fetal small intestine resulted in massive hypertrophy of the segment proximal to the site of obstruction. Villus morphology was grossly abnormal. Enterocytes developed many irregular features, most notably cytoplasmic extensions (pseudopods, or blebs) from their apical surface. Distal to the site of obstruction, morphological anomalies which resembled those seen after experimental oesophageal ligation were found. These included delayed disappearance of the apical endocytic network, disrupted or absent microvilli, glycogen accumulation and inappropriate cell extrusion. Proximal to the obstruction, where stasis of swallowed fluid occurs, distension and abnormal intestinal development ensues. Distal to the obstruction where the intestine develops in the absence of swallowed fluid, development is also abnormal. The anomalies resemble those noted after oesophageal ligation in utero, and possibly are the results of reduced cellular nutrition. These results suggest that fetal ingestion provides the developing gastrointestinal tract with an important stimulus for normal growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01606431
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  • 5
    Electronic Resource
    Electronic Resource
    Comparative study of histopathological alterations during intestinal infection of mice with pathogenic and non-pathogenic strains ofYersinia enterocolitica serotype O:8 (1993)
    Springer
    Virchows Archiv 423 (1993), S. 97-103 
    Details
    ISSN: 1432-2307
    Keywords: Yersinia enterocolitica ; Peyer's patches ; Ultrastructure ; M-cell ; Invasiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Yersinia enterocolitica is an invasive pathogen capable of causing a wide spectrum of gastrointestinal diseases in man. While there is a considerable body of data on the invasiveness ofY. enterocolitica in vitro, little is known about the events in vivo leading to the translocation of the bacteria from the intestinal lumen into the ileal tissue. There is no detailed ultrastructural information describing the course of infection of pathogenicY. enterocolitica in comparison with an avirulent strain. We compared a virulent plasmid-bearing strain and an isogenic avirulent plasmid-free derivative strain ofY. enterocolitica serotype O∶8 at the ultrastructural level, in the established model of murine yersiniosis. At 12 h postinoculation we found no indications of an active invasion of the intestinal epithelium, although microcolonies of the pathogenic strain were detectable closely under the follicle-associated epithelium of the Peyer's patches. The plasmid-bearing strain ofY. enterocolitica affected the gut-associated lymphoid tissue which was destroyed 36 h post-infection. Unlike the pathogenic strain ofY. enterocolitica, the nonpathogenic plasmid-free strain caused no detectable morphological alterations in the ileal tissue by this time. Morphological evidence is provided thatYersinia does not invade the ileal epithelium in an active manner, as has been observed in vitro, but appears to be transported across the epithelial barrier by M-cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01606583
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  • 6
    Electronic Resource
    Electronic Resource
    Cytogenetic study of botryoid rhabdomyosarcoma of the uterine cervix (1993)
    Springer
    Virchows Archiv 422 (1993), S. 87-91 
    Details
    ISSN: 1432-2307
    Keywords: Botryoid rhabdomyosarcoma ; Uterine cervix ; Immunohistochemistry ; Ultrastructure ; Chromosomal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report a case of sarcoma botryoides of the uterine cervix occurring in a 19-year-old woman. By light microscopy the tumor showed round and spindle cells with hyperchromatic nuclei and, focally, a cambium layer subjacent to the surface epithelium and surrounding endocervical glands. Strap-shaped cells with and without cross-striations and small foci of immature cartilage were also present. Immunohistochemical studies showed positive staining within the tumor cells for myoglobin, desmin, vimentin, muscle-specific actin and CD56. By electron microscopy, tumor cells showed cytoplasmic filaments in an alternating pattern of thick and thin filaments. Chromosomal analysis demonstrated deletion of the short arm of chromosome 1, and trisomies 13 and 18. To our knowledge, this is the first reported case of sarcoma botryoides of the endocervix with chromosomal analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605138
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  • 7
    Electronic Resource
    Electronic Resource
    Cellular and matrix changes in drug abuser liver sinusoids: A semiquantitative and morphometric ultrastructural study (1993)
    Springer
    Virchows Archiv 422 (1993), S. 145-152 
    Details
    ISSN: 1432-2307
    Keywords: Heroin ; Sinusoids ; Fibrosis ; Ultrastructure ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present work was to analyse, at the ultrastructural level, the action of heroin of 150 centrilobular sinusoids from liver biopsies of five intravenous drug abusers, who presented clinical and biological manifestations of hepatic impairment. A comparative study of 90 sinusoids from liver biopsies of three control patients was performed. Electron microscopic observations showed a thickening of the sinusoidal wall related to endothelial cell hypertrophy and to fibrosis of the space of Disse. This was generally associated with basement-membrane-like material and hepatocyte microvilli flattening. In addicts, hepatic vascular pole changes were a constant finding, accompanied by interhepatocyte space disjunction and perisinusoidal collagenization. Morphometric assessment confirmed a significant increase of sinusoidal wall surface, endothelial cell body and processes and Ito cell process surface was significantly different between the patient groups. This cellular hypertrophy may represent hyperactivation of the sinusoidal cell functional capacity, triggering the fibrogenesis in the space of Disse. While this mechanical barrier might hinder the free exchange through the space of Disse, it may equally well protect the liver against heroin toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01607166
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural study ofCryptococcus neoformans by quick-freezing and deep-etching method (1993)
    Springer
    Mycopathologia 121 (1993), S. 133-141 
    Details
    ISSN: 1573-0832
    Keywords: Capsule ; Cryptococcus neoformans ; Deep-etching ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The three-dimensional ultrastructure ofCryptococcus neoformans was studied by quick-freezing and deep-etching (QF-DE) method.C. neoformans, strain CDC551, was cultured on agar. The viable yeast cells (107 cells) were inoculated into each mouse from the tail vein. Three weeks after the inoculation, the brains of the mice were perfused with fixatives, quickly frozen, freeze-fractured, deeply etched and rotary shadowed with platinum and carbon. In addition, the viable cells ofC. neoformans on agar were picked up and quickly frozen, and replica membranes were prepared as described above. The ultrastructure ofC. neoformans was three-dimensionally demonstrated by the QF-DE method. The capsule was composed of fine meshworks of microfibrils (10–13 nm in diameter), which were directly attached to the cell walls. The capsule of the in vivo yeasts (yeast cells in the brain lesion) was thicker than that of the in vitro yeasts (yeast cells on agar culture). At the outer part of the cell wall, a particle-accumulating layer was observed. This layer in vivo was thicker than that in vitro. Occasionally, the yeast cells were ingested by phagocytes in the mouse brain. Although the cytoplasm of such yeast cells was destroyed, the capsular meshworks were well preserved. The ultrastructure of the capsule was the same both in cultured and phagocytized yeasts in the cystic lesions of the brains. This lack of morphological changes of the capsular meshworks suggests that they are resistant to the digestion by phagocytes. This stability of capsular structures may provide one of the important pathogenic factors in cystic lesions byC. neoformans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01104068
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  • 9
    Electronic Resource
    Electronic Resource
    Morphological assessment of ethyl choline mustard aziridinium-induced neurotoxicity in rat brain reaggregate cultures (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 154-162 
    Details
    ISSN: 1432-0533
    Keywords: Ethylcholine mustard aziridinium (ECMA, AF64A) ; Brain reaggregate cultures ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Foetal rat brain reaggregate cultures have been employed to investigate the morphological changes associated with the neurotoxic action of ethylcholine mustard aziridinium (ECMA). In a companion study we provided evidence for apparent selective cholinergic neurotoxicity. Exposure of 9-day-old cultures to 12.5 μM ECMA for 3 days produced dilatation of selected axon preterminals and terminals in the outer core tissue layer. Axoplasm in these dilated terminals was electron lucent and contained a flocculent, plasma-like material with remnants of the smooth endoplasmic reticulum. Their synaptic vesicle content was much reduced or, absent. Microglial cells were engaged in phagocytosis of these effete structures and a few necrotic neurons were enveloped by glial processes. Exposure to 50 μM ECMA produced widespread necrosis with some surviving neurons, surrounded by the still-persisting capsular layer. Treatment with 100 μM ECMA generated a greater extent of tissue necrosis, with only a few surviving neurons and glial cells being contained within the necrotic tissue mass. Reaggregates frequently disintegrated following capsule loss. Our results indicate that the initial morphological manifestation of ECMA-induced toxicity is dilatation of axon terminals, that are probably of cholinergic origin and are targeted due to their possession of the high-affinity choline transport system which is unique to these neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334882
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  • 10
    Electronic Resource
    Electronic Resource
    Nephrosialidosis: ultrastructural and lectin histochemical study (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 198-205 
    Details
    ISSN: 1432-0533
    Keywords: Nephrosialidosis ; Sialidosis ; α-neuraminidase deficiency ; Ultrastructure ; Lectin histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The neuropathological findings in a Japanese male with nephrosialidosis are reported. Clinically, coarse face, psychomotor retardation, macular cherryred spot and proteinuria were noted at 1 year and 7 months. He was diagnosed to have nephrosialidosis on the basis of a deficiency of α-neuraminidase activity in both lymphocytes and cultured skin fibroblasts, and of severe glomerular and tubular involvement on renal biopsy. He died of multiple organ failure at 8 years and 6 months. There were numerous vacuoles and storage materials in visceral organs, particularly in the glomerular and tubular epithelial cells of the kidney and Kupffer cells as well as hepatocytes in the liver. Neuropathological examination revealed severe neuronal storage in the selected part of the central nervous system; lower motor neurons of the brain stem and spinal anterior horn cells, as well as neurons in the basal nucleus of Meynert. In the peripheral nervous system, sympathetic ganglia were severely affected. There was little or no neuronal storage in the basal ganglia, cerebral cortex or cerebellum, and demyelination was not found. Electron microscopic examination showed fine wavy multilamellar structures in the spinal anterior horn cells or Zebra body-like structures in the neurons of the Meynert's basal nucleus. Lectin histochemistry was positive for wheat germ agglutinin, Ricinus communis agglutinin-1 and peanut agglutinin within distended neurons. We conclude that the neuropathological feature in nephrosialidosis is not specific except for the selectiveness of the anatomical sites of involvement. It shares some aspects found in other types of sialidosis or galactosialidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334891
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  • 11
    Electronic Resource
    Electronic Resource
    A simple method of rapid freezing adequately preserves brain tissue for immunocytochemistry, light and electron microscopic examination (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 645-650 
    Details
    ISSN: 1432-0533
    Keywords: Brain ; Freezing ; Immunocytochemistry ; Microscopy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A simple and reproducible method for cryo-preservation of brain tissue from patients with Alzheimer's disease is described. Fresh brain slices (1 cm thick) obtained less than 6 h postmortem are placed in sealed plastic bags, sandwiched between 0.3-cm-thick aluminium sheets, and frozen by placing the entire “sandwich” between layers of dry ice pellets. The frozen brain slices are stored at −85 °C. Specific anatomic areas can be retrieved at any time for light and electron microscopic, immunocytochemical, autoradiographic and neurochemical studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294305
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  • 12
    Electronic Resource
    Electronic Resource
    Stereological and morphometric analysis of dermal fibroblasts before and after bone marrow transplantation in a case of mucopolysaccharidosis I Scheie phenotype (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 21-28 
    Details
    ISSN: 1432-0533
    Keywords: Mucopolysaccharidosis I Scheie phenotype ; Bone marrow transplantation ; Fibroblasts ; Stereologic analysis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bone marrow transplantation (BMT) has been used therapeutically in several types of mucopoly-saccharidoses (MPS) and other inherited metabolic disorders. Fibroblasts are severely affected in MPS due to the intralysosomal accumulation of glycosaminoglycans. We report a stereological and morphometric study at light and electron microscopy levels of dermal fibroblasts before and 21 months after BMT in a young girl with MPS I Scheie phenotype (MPS I-S). Dermal fibroblasts showed remarkable morphological changes although their density, expressed as number of fibroblasts per unit volume of dermis (number density), was not modified in the post-BMT samples as compared to pre-BMT ones. Stereological and morphometric parameters referring to cell characteristics of post-BMT fibroblasts (nuclear and cell surface densities, and both nucleus/cell and cell/nucleus volume densities) showed significant differences when compared with pre-BMT fibroblasts, and non-significant differences regarding control cells. On the other hand, quantitative parameters of the lysosomal compartment from post-BMT fibroblasts showed intermediate values between pre-BMT and control fibroblasts. These results, at cellular level, are in agreement with previous biochemical and clinical results, and clearly showed a progressive course to a non-pathological state. All parameters estimated may be considered useful tools in evaluating the success of BMT. These parameters provide quantitative data which can be statistically compared, showing the changes due to the reduction of storage material after BMT. Cell/nucleus volume density is especially interesting since not only is it easy to estimate, even by automatic procedures, but it could also constitute a numerical expression of skin anatomopathological analyses performed post-BMT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454894
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  • 13
    Electronic Resource
    Electronic Resource
    Rosenthal fibers producing a granular cell appearance in a glioblastoma (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 100-104 
    Details
    ISSN: 1432-0533
    Keywords: Glioblastoma ; Granular cell tumor ; Intermediate filaments ; Rosenthal fibers ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this report we describe a glioblastoma multiforme with focal granular cell change. In most astroglial tumors with granular cells, the granular appearance is due to the presence of periodic acid-Schiff-positive, membrane-bound cellular debris. In the present case the granular appearance was due to the presence of many small Rosenthal fibers, which were immunoreactive for glial fibrillary acidic protein, vimentin, ubiquitin, and heat-shock protein 27, but not for α-B crystallin. The ultrastructural characteristics are described. These findings demonstrate that granulofilamentous inclusions with the appearance of Rosenthal fibers in glial tumors are a structurally heterogeneous feature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454907
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  • 14
    Electronic Resource
    Electronic Resource
    Intracranial extraskeletal myxoid chondrosarcoma with special reference to lamellar inclusions in the rough endoplasmic reticulum (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 525-528 
    Details
    ISSN: 1432-0533
    Keywords: Extraskeretal myxoid chondrosarcoma ; Ultrastructure ; Collagen type II ; Rough endoplasmic reticulum ; Lamellar inclusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An extraskeletal myxoid chondrosarcoma in the pineal region was studied by light and electron microscopy. The immunohistochemical positivity for S-100 protein, vimentin and collagen type II favored a chondrocytic origin of the tumor. In addition to the well-described ultrastructural features suggestive of a cartilagenous nature, this tumor had unusual lamellar inclusions in the rough endoplasmic reticulum. To the best of our knowledge, this is the first report of these special inclusion bodies in a myxoid chondrosarcoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228591
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  • 15
    Electronic Resource
    Electronic Resource
    Uncommon types of polyglucosan bodies in the human brain: distribution and relation to disease (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 484-490 
    Details
    ISSN: 1432-0533
    Keywords: Polyglucosan bodies ; Bielschowsky bodies ; Adult polyglucosan body disease ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The significance of the development of polyglucosan bodies (PBs) in the CNS is incompletely understood. We present the clinicopathological features of three autopsy cases with numerous PBs other than the common corpora amylacea or Lafora bodies. The first patient had pleomorphic PBs in the neuronal processes of pallidum and substantia nigra which, thus, are consistent with Bielschowsky bodies. Bielschowsky bodies involved also the hypothalamus and tegmentum of midbrain and medulla. The present case was the first not associated with any clinical symptoms. The second patient also had incidental Bielschowsky bodies in the external pallidum, substantia nigra, and pallidothalamic, pallidonigral and nigrostriatal tracts. Additionally, unique clusters of small PBs appeared in the cerebral cortex, putamen, pallidum, and caudate nucleus. Immunostaining suggested that these small clustered PBs were located in the cytoplasm and processes of astrocytes. Ultrastructurally, these clustered PBs were in agreement with previous descriptions of PBs. The third patient had adult polyglucosan body disease. Most PBs in the white matter were corpora amylacea situated in astrocytic processes or axons. In the gray matter, many pleomorphic PBs resembling Bielschowsky bodies occurred in neuronal processes. In the peripheral nervous system, a few PBs were seen in myelinated axons. The following conclusions may be drawn from this study: (1) each type of PBs develops in distinct cell types of the human brain in variable distribution; (2) Bielschowsky bodies may not manifest clinically; (3) PBs other than corpora amylacea or Lafora bodies may be distributed in localized or diffuse patterns; (4) in the localized pattern (patients 1 and 2), PBs occur as Bielschowsky bodies or clustered PBs, and tend to involve certain systems (pallidum, striatum, and substantia nigra); and (5) in the diffuse pattern (patient 3), PBs develop as corpora amylacea and Bielschowsky-like bodies of adult polyglucosan body disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228584
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  • 16
    Electronic Resource
    Electronic Resource
    Ontogenesis of the rabbit pituitary intermediate lobe (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 87-97 
    Details
    ISSN: 1432-0568
    Keywords: Pituitary intermediate lobe ; Rabbit ; Ontogenesis ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the intermediate lobe of the rabbit pituitary was investigated by light and electron microscopy and by using immunocytological techniques. The first immunoreactive melanotrophic cells were detected at the fetal day 17 in the dorsal zone of Rathke's pouch epithelium facing the neural lobe; this coincided ultrastructurally with the appearance in this area of a few cells exhibiting secretory vesicles and granular condensations in the Golgi saccules. The differentiation of the gland probably required an infundibular inductive effect. Secretory cells increased in number following a dorsoventral gradient during the next fetal and neonatal stages until postnatal day 20, the stage at which the intermediate lobe exhibited its definitive organization. The gland innervation occurred during the first days after birth. The advent of these oxytocin- and neurophysin-immunoreactive fibres coincided with an obvious stimulation of the synthetic activity of the melanotrophic cells. The possible neurotrophic effect of these cells on their innervating system remains to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208199
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  • 17
    Electronic Resource
    Electronic Resource
    The ciliary ganglion of the cat: a light and electron microscopic study (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 591-599 
    Details
    ISSN: 1432-0568
    Keywords: Ciliary ganglion ; Quantitative study ; Ultrastructure ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ciliary ganglia of eight healthy adult cats were studied by light and electron microscopy. The ganglion, measuring about 2 mm in length, was consistently found to be attached to the branch from the oculomotor nerve supplying the inferior oblique muscle. The number of neurons varied from 2773 to 3794 after applying Abercrombie's correction. The mean of average somal diameter of the neurons was 36.5 μm (SD = 5.0 μm) and the mean of somal cross-sectional area was 904.2 μm2 (SD = 262.8 μm2). The mean of average nuclear diameter was 13.9 urn (SD = 1.8 μm) and the mean of nuclear cross-sectional area was 142.2 μm2 (SD = 37.1 μm2). The mean of the aspect ratios of the soma and nucleus were 1.2 (SD = 0.1) and 1.1 (SD = 0.1) respectively. The frequency distributions of these parameters were all unimodal. Under the light microscope, the Nissl granules in the neurons were prominent and were distributed peripherally, perinuclearly or randomly in the cytoplasm. Under the electron microscope, the rough endoplasmic reticulum showed a similar pattern of distribution in the cytoplasm. In some neurons, glycogen-like granules were present; these were either distributed randomly throughout the cell, or aligned in single rows in relation to sub-surface cisterns and between the cisterns of smooth and rough endoplasmic reticulum. Most of the dendrites were short protrusions from the cell body; some contained glycogen-like granules. Occasionally, the dendritic protrusions were electron-dense. All the synapses encountered were axodendritic. In most axon terminals, the synaptic vesicles were spherical and measured 30–50 nm in diameter; in some, they were flattened, measuring 50 nm by 20 nm. Some axon terminals containing either spherical or flattened synaptic vesicles also contained large dense-cored vesicles that measured 80–100 nm, while their dense core measured 40–60 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214438
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  • 18
    Electronic Resource
    Electronic Resource
    Morphological analysis of in vitro human hair growth (1993)
    Springer
    Archives of dermatological research 285 (1993), S. 158-164 
    Details
    ISSN: 1432-069X
    Keywords: Hair follicle ; Culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The histological and ultrastructural aspect of normal human hair follicles maintained ex vivo for 12 days was evaluated. Anagen hair follicles, dissected free of contaminating connective tissue, were maintained for up to 12 days in a serum-free medium. Macroscopic observations revealed continued viability for 12 days, at which time some follicles involuted in a manner morphologically similar to catagen. Increased growth of maintained follicles was measured from the abrupt ending of the connective tissue sheath (CTS), as no increase in this component was observed from initiation of culture. In general follicles maintained up to 8 days exhibited little divergence from normal in vivo morphologies including the persistence of functional hair bulb melanocytes — a marker of anagen. After this time melanin granules were present in dermal papilla cells, as occurs during impending involution in vivo. Heterotypic cell contact occurred in the middle to upper follicle between outer root sheath (ORS) keratinocytes and disorganized CTS. Herniation of some ORS cells away from the follicle and the occurrence of loose desmosomal junctions between ORS keratinocytes reflected loss of normal follicular cell interactions in upper follicles maintained after 8 days. Continued follicle growth correlated with the presence of mitotic matrix keratinocytes even at 12 days. After 12 days in culture most follicles involuted displaying apoptotic-like keratinocytes and hair bulb melanocytes and the presence of highly keratinized hair ‘club’ structures. While most follicles exhibited this orderly sequence of events, a few follicles involuted after 24 h with synchronous degeneration of all cells. Two follicles exhibited upregulated cortical cell differentiation at the level of the dermal papilla (DP). Normal cell cytoplasmic constituents were replaced with ribosomes and keratin bundles. This study reveals for the first time the histology and ultrastructure of normal hair follicles in culture for up to 12 days in serum-free medium. Although involuted hair follicles may exhibit some features of catagen, it is possible that the mechanisms involved are entirely different.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01112919
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  • 19
    Electronic Resource
    Electronic Resource
    Mayflies (ephemeroptera), the most “primitive” winged insects, have telotrophic meroistic ovaries (1993)
    Springer
    Development genes and evolution 203 (1993), S. 18-27 
    Details
    ISSN: 1432-041X
    Keywords: Oogenesis ; Germ line cell cluster ; Oocyte determination ; Ultrastructure ; Mayflies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germ line cell cluster formation in ovarioles of three different stages, each from a different mayfly species, was studied using ultra-thin serial sectioning. In the analysed ovariole of Cloeön sp., only one linear, zigzag germ line cell cluster was found, consisting of sibling cells connected by intercellular bridges which represent remnants of preceding synchronized mitotic cycles followed by incomplete cytokinesis. A polyfusome stretched through all sibling cells. At the tip of the ovariole, cytokinesis occurred without preceding division of nuclei; thus, intercellular bridges were lined up but the remaining cytoplasm between the bridges had no nuclei. The analysed Siphlonurus armatus vitellarium contained five oocytes at different stages of development. Each oocyte in the vitellarium was connected via a nutritive cord to the linear cluster of its sibling cells in the terminal trophic chamber. Each cluster had the same architecture as was found in Cloëon. The 3-dimensional arrangement and distribution of closed intercellular bridges strongly suggest that all five clusters are derived from a single primary clone. The position of oocytes within each cluster is random. However, each oocyte is embraced by follicular or prefollicular cells whilst all other sibling cells are enclosed by somatic inner sheath cells, clearly distinguishable from prefollicular cells. In the analysed ovariole of Ephemerella ignita, two small linear clusters were found in the tropharium beside two single cells, two isolated cytoplasmic bags with intercellular bridges but no nuclei, and some degenerating aggregates. One cluster was still connected to a growing oocyte via a nutritive cord. In all species the nurse cells remained small and no indications of polyploidization were found. We suggest that this ancient and previously unknown telotrophic meroistic ovary has evolved directly from panoistic ancestors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00539886
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  • 20
    Electronic Resource
    Electronic Resource
    Ultrastructural expression of cytoplasmic male sterility in sugar beet (Beta vulgaris L.) (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 22-32 
    Details
    ISSN: 1432-2145
    Keywords: Cytoplasmic male sterility ; Ultrastructure ; Mitochondria morphometry ; Beta vulgaris L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of microspore mother cells (MMC) and tapetum in male-fertile and male-sterile anthers of Beta vulgaris L. was compared at the electron microscope level. These studies were complemented by morphometric analyses of mitochondria in both tissues through successive stages of microsporogenesis. The earliest irregularities in the ultrastructure of male-sterile anthers were noted within the tapetum at the tetrad stage. These disturbances were initially expressed by a slight reduction in mitochondrial size and the appearance of concentric configurations of endoplasmic reticulum. As development proceeded, a further decrease in mitochondrial size become more conspicuous and was accompanied by a reduction in ribosome population and a failure of the tapetum to produce Ubisch bodies. This failure to produce Ubisch bodies is reflected in the underdevelopment of sterile microspore exine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227579
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  • 21
    Electronic Resource
    Electronic Resource
    Megaspore development in Selaginella. I. “Wicks”, their presence, ultrastructure, and presumed function (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 98-107 
    Details
    ISSN: 1432-2145
    Keywords: Selaginella ; Megaspore ; Exospore ; Ultrastructure ; Tapetal cells ; Plasmodesmata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Structures have been found in the locular space between the tapetal cells and megaspores in Selaginella argentea and S. kraussiana that enter the megaspore wall and extend to the plasma membrane of the megaspore cytoplasm. We have called these structures “wicks”. Unless special fixation procedures are used wicks are either very poorly preserved or not apparent. Wicks appear to be routes for the transport of materials from the tapetum to developing megaspores. The entry of the wicks into the megaspore wall and their passage throughout the wall implies that the megaspore wall of Selaginella is a three-dimensional mesh-work of inter-connecting spaces. Wicks have several macromolecular-sized subunits, and the results of our histochemical reactions indicated the presence of glycoprotein and/or mucopolysaccharide. X-ray microanalysis of the S. convoluta exospore showed that silicon is present in rod-shaped structures between units of the exospore in mature megaspores. Because of the size and form of the structures between the exospore units we consider that they are remnants of wicks stabilized by silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227654
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  • 22
    Electronic Resource
    Electronic Resource
    Chemical agents that inhibit pollen development: effects of the phenyl-cinnoline carboxylates SC-1058 and SC-1271 on the ultrastructure of developing wheat anthers (Triticum aestivum L. var Yecora rojò) (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 108-212 
    Details
    ISSN: 1432-2145
    Keywords: Wheat pollen ; Chemical hybridizing agents ; Male sterility ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phenylcinnoline carboxylate compounds SC-1058 and SC-1271 cause complete male sterility in wheat when applied at suitable dosages at the pre-meiotic stage of anther development. Anthers from treated and untreated plants were compared using light and electron microscopy from the pre-meiotic stage through the formation of nearly mature pollen. Overall anther development is gradually slowed in treated plants and pollen development is generally arrested in the late prevacuolate or early vacuolate microspore stage, although the first pollen mitosis does sometimes occur. The sporopollenin-containing exine walls are thinner, and show abnormally developed foot and tectum layers with sparse connecting baculi. Microspore cytoplasm degenerates and the cells eventually collapse. At the early, prevacuolate, free microspore stage treated tapetal cells hypertrophy, expanding into the locule. They contain abnormally large vacuoles that appear to form from the fusion of secretory vesicles, and some vacuoles contain electrondense deposits. The sporopollenin-containing orbicular wall and Ubisch bodies are retarded in their development and are structurally deformed. Acetolysis of whole anthers and of thick sections shows that the sporopollen-in-containing structures of treated materials are greatly reduced in thickness and are less rigid than in the control. We conclude that application of these compounds causes interference with the secretory function of tapetal cells which supplies sporopollenin cell-wall polymers to the exine of the microspores and to the tapetal orbicular wall and associated Ubisch bodies. Interference with the tapetal secretion of other nutrients required for microspore development is strongly suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227655
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  • 23
    Electronic Resource
    Electronic Resource
    The embellum: a newly defined structure in the grass ovule (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 191-198 
    Details
    ISSN: 1432-2145
    Keywords: Micropyle ; Transfer cells ; Ultrastructure ; Nucellus ; Poaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several kinds of outgrowth from the grass ovule are known. Attention is focused here on one outgrowth that occurs within or around the micropyle and is of nucellar origin. Grass species in which it is currently known to occur are listed and examples of variants briefly described. Attention is concentrated upon Pennisetum, where the cell structure is described in detail with a series of electron photomicrographs. The tissue representing an aggregation of these transfer cells is newly named with the term ‘embellum’, and its significance for pollen tube growth is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228648
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  • 24
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in the appendix of the Sauromatum guttatum inflorescence during anthesis (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 153-170 
    Details
    ISSN: 1432-2145
    Keywords: Appendix ; Sauromatum guttatum ; Ultrastructure ; Mitochondrion ; Amyloplast ; Peroxisome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the epidermal and sub-epidermal cells of the appendix of the Sauromatum guttatum inflorescence reveals developmental changes during anthesis. These changes precede, and probably make possible, heat and odor production. Two days before D-day (the day of heat production and inflorescence-opening) the mitochondria of the epidermis divide; apparent division of the amyloplasts was observed at the same time. The presence of lipid bodies and peroxisomes in the epidermis was clearly evident. On D-day, the epidermis becomes a continuous layer in which the cell walls separating two adjacent cells disappear. At the same time, in the sub-epidermal cells, the mitochondria and the amyloplasts undergo division. The mitochondria become electron-dense, and their DNA is clearly visible. On that day, lipids as well as starch are being depleted. The peroxisomes change in structure every day, from D-2 to D-day. It has also been demonstrated by histochemical techniques that during anthesis the activity of cytochrome c oxidase (3,3-diaminobenzidine as a substrate) decreases whereas the activity of NADH dehydrogenase [tetrazolium salts: nitro-blue tetrazolium chloride (NBT) or neotetrazolium chloride (NT) in the presence of NADH], increases. Oxygen consumption of isolated mitochondria from the D-day appendix was inhibited in the presence of the two tetrazolium salts to a different degree: oxidation of NADH in the presence of NBT was the most sensitive to inhibition, more so than the oxidation of malate and succinate. NT was less effective as an inhibitor in the presence of those three respiratory substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228644
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  • 25
    Electronic Resource
    Electronic Resource
    Ultrastructure of the cortical epithelium of the rat thymus after in vivo exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (1993)
    Springer
    Archives of toxicology 67 (1993), S. 558-564 
    Details
    ISSN: 1432-0738
    Keywords: 2,3,7,8-Tetrachlorodibenzo-p-dioxin ; TCDD ; Thymus ; Epithelium ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known for inducing cortical atrophy in the rat thymus. The present study was conducted to provide ultrastructural evidence for the cortical epithelium to be a target for TCDD in vivo. Juvenile male Wistar rats were orally intubated once with either 50 or 150 μg/kg TCDD and killed 4 or 10 days thereafter. Major changes were found in the cortical thymic epithelium. First, a relative shift occurred from “pale” to darker cortical epithelial cell types, as judged by their nuclear and cytoplasmic electron density. This effect was most prominent at 10 days after exposure to 150 μg/kg TCDD. The increased electron density of the cortical epithelium indicates an altered state of cellular differentiation. Secondly, at the 150 μg/kg dose level focal epithelial cell aggregates were seen both at day 4 and day 10 after administration. This aggregation may either be compound induced or represent a secondary event to the collapse of the thymic stroma. Thirdly, increased vacuolation of cortical epithelial cells was apparent. This effect is interpreted as a consequence rather than a cause of thymocyte depletion from the cortex. This study indicates that TCDD exposure affects the cortical epithelium of the rat thymus at a high dose level. Electron microscopy reveals that the differentiation of epithelial cells is altered. In addition, epithelial cell aggregates are formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01969269
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  • 26
    Electronic Resource
    Electronic Resource
    Identification of Naemacyclus minor hyphae within needle tissues of Pinus sylvestris by immunoelectron microscopy (1993)
    Springer
    Archives of microbiology 160 (1993), S. 265-272 
    Details
    ISSN: 1432-072X
    Keywords: Pinus sylvestris ; Naemacyclus minor ; Immunocytochemical identification ; Ultrastructure ; Plant-fungus interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultural investigations revealed that Naemacyclus minor, Lophodermium seditiosum and Cenangium ferruginosum were the most frequent colonizers of asymptomatic and symptomatic Pinus sylvestris needles. Since ultrastructural observations showed that morphological features were not suitable to differentiate hyphae of N. minor from hyphae of other isolates, the on-section immunogold labelling technique was applied in combination with an anti-N. minor specific immunoserum. The specificity of this serum was tested against culture hyphae of all isolates. Anti-N. minor specific immunoserum was then used to identify N. minor hyphae in thin sections of green P. sylvestris needles. The infection loci identified were restricted to small tissue areas located in the vicinity of stomata. In the hypodermis, hyphae and endocell-containing hyphae were located within the lumina of host cells but outside the protoplast. The growth of hyphae from cell to cell occurred through pits. The hyphae spreat into the mesophyll intercellularly and continued with the intracellular colonization of moribund and dead mesophyll cells in a later stage of infection. The observed host-parasite interactions at cellular and ultrastructural level are discussed in connection with the still controversial interpretation of the pathogenicity of N. minor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292075
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  • 27
    Electronic Resource
    Electronic Resource
    Ultrastructure of Bacillus pulvifaciens (1993)
    Springer
    Archives of microbiology 159 (1993), S. 114-118 
    Details
    ISSN: 1432-072X
    Keywords: Bacillus pulvifaciens ; Vegetative cells ; Spotes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of vegetative cells and spores of Bacillus pulvifaciens was studied by CTEM and SEM methods. The vegetative cells are rods, 1.6–4.5 μm long and 0.4–0.6 μm wide, exhibiting typical ultrastructural features of Gram-positive bacteria. The spores are of ellipsoidal shape, 0.6×1.2 μm in size, with six longitudinal ribs reaching up to 130 nm in height. There are satelite ribs on both sides of the longitudinal ribs, reaching up to 20 nm in height. Between the longitudinal ribs, additional transversal ribs were observed in SEM. A special tubular layer, separating the outer and inner coat of the spores, was revealed in ultrathin sections. This layer seems to be a typical ultrastructural feature of Bacillus pulvifaciens spores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250269
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  • 28
    Electronic Resource
    Electronic Resource
    Development of quasi-multicellular bodies of Treponema denticola (1993)
    Springer
    Archives of microbiology 160 (1993), S. 206-213 
    Details
    ISSN: 1432-072X
    Keywords: Treponema denticola ; Spirochetes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of quasi-multicellular bodies of Treponema denticola was analysed using different electron microscopical methods. These bacteria could develop four different conformations: (i) normal helical forms; (ii) twisted spirochetes, forming plaits; (iii) twisted spirochetes, forming club-like structures; (iv) spherical bodies in different size. Treponemes within spherical bodies, plaits, and clubs proved to be enclosed in a common outer sheath in which the normal arrangement of their axial flagella was lost. The development of the quasi-multicellular bodies starting from the monoforme spirochetes was elucidated and this morphogenetic process is illustrated by a schematic drawing. Factors which might be involved in the induction of the structures are discussed and their possible pathogenetic importance is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249126
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  • 29
    Electronic Resource
    Electronic Resource
    Avian epidermis contains ATPase- and Ia-positive Langerhans-like cells (1993)
    Springer
    Cell & tissue research 271 (1993), S. 103-106 
    Details
    ISSN: 1432-0878
    Keywords: Skin ; Langerhans cell ; ATPase-histochemistry ; Ultrastructure ; Ia antigen ; Four avian species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The occurrence of cells resembling mammalian Langerhans cells in the avian epidermis was studied by ATPase histochemistry, Ia immunoreactivity and electron microscopy. The existence of MHC class II antigen-(Ia) expressing, ATPase-positive dendritic cells, which are ultrastructurally similar to mammalian Langerhans cells except for the absence of Birbeck granules, was demonstrated. These cells may be a basic component of the immune system of birds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297547
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  • 30
    Electronic Resource
    Electronic Resource
    Development of the diffuse endocrine system in the chicken proventriculus (1993)
    Springer
    Cell & tissue research 271 (1993), S. 107-113 
    Details
    ISSN: 1432-0878
    Keywords: Proventriculus ; Endocrine ontogenesis ; Ultrastructure ; Regulatory peptides ; Immunocytochemistry ; Silver impregnations ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of endocrine cells in the chicken proventriculus has been investigated using light-and electron-microscopy in conjunction with silver and immunocytochemical techniques. The first morphologically detectable endocrine cells were found in 5-day-old embryos by electron microscopy. From the 9th to the 13th day, endocrine cells in contact with the lumen of the organ could be detected both by electron and light (silver impregnation) microscopy. The number of open-type endocrine cells progressively decreased and the number of closed-type increased after this stage. Until the 16th day, endocrine cells were located exclusively in the luminal epithelium, but afterwards they appeared in progressively greater numbers in the compound glands. After hatching, long cytoplasmic processes could be seen in the endocrine cells. Immunoreactivities to regulatory substances appeared in the following order: serotonin (day-14), avian pancreatic polypeptide, glucagon and somatostatin (day-16), bombesin and neurotensin (day-18), and finally, met-enkephalin (day-21).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297548
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  • 31
    Electronic Resource
    Electronic Resource
    Immunocytochemical effects of thyroxine stimulation on the adenohypophysis of dwarf (dw) mutant mice (1993)
    Springer
    Cell & tissue research 274 (1993), S. 579-585 
    Details
    ISSN: 1432-0878
    Keywords: Thyroxine ; Pituitary gland, pars distalis ; Immunocytochemistry ; Ultrastructure ; Mouse (Snell dwarf)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effects of dietary thyroxine on the immunoreactivity of cells in the pars distalis of the adenohypophysis in dwarf (dw/dw) mice were determined by ultrastructural immunocytochemistry. In nontreated dwarfs only adrenocorticotropic hormone (ACTH) cells and luteinizing hormone (LH) cells showed positive reactions to their respective antibodies, whereas no cells showed immunoreactivity to antibodies to growth hormone (GH), thyroid-stimulating hormone (TSH), or prolactin (Prl). In dwarfs supplemented postnatally with dietary thyroxine for 9 wks, the treatment failed to produced immunoreactive GH, TSH or Prl cells. However, LH cells became more prominent and fully developed, with denser concentrations of immunoreactive particles overlying the secretory granules than occurred in nontreated dwarfs. In thyroxine-treated dwarfs, ACTH cells were similar in ultrastructural features and immunoreactivity to those in nontreated dwarfs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314556
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  • 32
    Electronic Resource
    Electronic Resource
    Biphasic effect of ACTH on growth of rat adrenocortical cells in primary culture (1993)
    Springer
    Cell & tissue research 271 (1993), S. 169-176 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Differentiation ; Tissue culture ; Proliferation ; Ultrastructure ; Steroids ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proliferation rate of differentiating fetal rat adrenocortical cells was studied in primary culture. In this system, stimulation with ACTH induces differentiation of zona glomerulosa-like cortical cells into zona fasciculata-like cells. Incorporation of bromodeoxyuridine (BrdU) was studied immunocytochemically by use of anti-BrdU antibody, and the proliferation rate was counted from the monolayer colonies of adrenocortical cells. After 21 days of cultivation in the absence of ACTH, the proliferation rate of zona glomerulosa-like cells was 10%. The rate slowly declined to 1% at the age of 100 days during continuous cultivation in the absence of ACTH. Stimulation with ACTH induced a strong inhibition in the proliferation rate (down to 2% during the first 24 h). Treatment with ACTH during the following 48 h led to an extremely intense proliferation of adrenocortical cells at a proliferation rate of 25%. Continuous treatment with ACTH up to 100 days led to a persistent growth of adrenocortical cells, and a proliferation rate over 2-fold higher than in control cells cultivated in the absence of ACTH. Thus, ACTH is the principal growth-promoting factor also in vitro, as has been found in in vivo studies. This growth effect is mediated by a biphasic course; at the beginning of differentiation the effect is inhibitory and is followed by a persistent stimulation of the growth of adrenocortical cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297555
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  • 33
    Electronic Resource
    Electronic Resource
    Ultrastructure and morphometry of testicular Leydig cells and the interstitial components correlated with testosterone in aging rats (1993)
    Springer
    Cell & tissue research 271 (1993), S. 241-255 
    Details
    ISSN: 1432-0878
    Keywords: Leydig cell ; Testis ; Interstitium ; Aging ; Ultrastructure ; Morphometry ; Testosterone ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ultrastructure of testicular interstitium in young and aged adult rats was analysed using morphometric methods, and the plasma testosterone concentration was measured. With increasing age there was an augumentation in the volume of collagen fibrils in the intercellular matrix and in blood vessels. During the aging process (approximately two years) the average volume of the Leydig cell decreased from 1364 μm3 to 637 μm3, but the number of Leydig cells in paired testes increased from 53x106 to 113x106. The absolute volume of smooth surfaced endoplasmic reticulum (SER) per Leydig cell amounted in aged rats to 78% of that in young adult rats. The total amount of SER in paired testes increased by 62% with aging. The present analysis suggests that the ability of SER to maintain peripheral testosterone concentration decreases with age. In young adult rats the absolute volume of peroxisomes per Leydig cell correlated significantly with the concentration of testosterone in blood and also with the absolute volume of SER per Leydig cell. These results combined with ultrastructural observations of close apposition of peroxisomes and SER suggest that peroxisomes have a role in testosterone secretion by Leydig cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318610
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  • 34
    Electronic Resource
    Electronic Resource
    Effect of omeprazole-evoked hypergastrinemia on ultrastructure of enterochromaffin-like cells in the stomach of portacaval-shunted rats (1993)
    Springer
    Cell & tissue research 272 (1993), S. 71-77 
    Details
    ISSN: 1432-0878
    Keywords: Enterochromaffin-like cells ; Hypergastrinemia ; Hypertrophy ; Ultrastructure ; Omeprazole ; Portacaval shunt ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-producing enterochromaffinlike (ECL) cells in the acid-producing portion of the rat stomach responded to long-standing hypergastrinemia (omeprazole treatment daily for 8–10 weeks) with hypertrophy (and hyperplasia) and with a reduced number of granules and vesicles per unit cytoplasm. There was a reduction in the ratio of electron-dense granules versus vesicles and an increase in the profile diameter of the vesicles. Also, portacaval shunting (PCS) induced changes in the ECL cells, manifesting (i) as an increase in cell number and size, and (ii) as a reduced number of granules and vesicles per unit area. The cytoplasmic granules and vesicle profiles were enlarged, and the ratio of granules versus vesicles was reduced. The combination of PCS and long-standing hypergastrinemia (omeprazole treatment) produced a greatly enhanced ECL cell hypertrophy (and hyperplasia) and a marked reduction in the number of granules. The ratio of granules versus vesicles was markedly reduced while the profile diameters of both granules and vesicles were increased. The relative predominance of very large vesicles (vacuoles) was a prominent feature of the ECL cells in these rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323572
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  • 35
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    Electronic Resource
    Ultrastructure of free nerve endings in respiratory and squamous epithelium on the rat nasal septum (1993)
    Springer
    Cell & tissue research 274 (1993), S. 329-335 
    Details
    ISSN: 1432-0878
    Keywords: Intraepithelial axons ; Free nerve endings ; Nasal mucosa ; Ultrastructure ; Enzyme histochemistry ; Immunocytochemistry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of nerve fibres in the mucosa of the nasal septum of the rat was investigated by means of transmission electron microscopy on transverse and tangential ultrathin sections. Near the basement membrane of respiratory and squamous epithelium, a rather dense network of unmyelinated nerve fibres occurs. Some fibres in the respiratory epithelium ascend between the epithelial cells to reach up to the tight junctions. These fibres appeared in transverse sections to end as hooks or boutons, sometimes with branches. These shapes resemble the free nerve endings that are considered to act as nociceptors. The small intraepithelial fibres, with diameters of about 0.5–1 μm, contain both dense granules and clear vesicles comparable to synaptic vesicles. Substance P was found in dense granules in basal fibres; vasoactive intestinal peptide was absent throughout the epithelium. Acetylcholinesterase activity was observed closely associated with the basal fibres; the apical fibres showed little if any activity. Membrane specializations pointing to an efferent function as well as structures usually associated with mechanoreceptive functions were lacking in both respiratory and squamous epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318751
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  • 36
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    Electronic Resource
    The effects of gonadectomy and testosterone treatment on the Harderian gland of the green frog, Rana esculenta (1993)
    Springer
    Cell & tissue research 273 (1993), S. 201-208 
    Details
    ISSN: 1432-0878
    Keywords: Harderian gland ; Castration ; Testosterone ; Ultrastructure ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effects of gonadectomy and testosterone treatment on the fine structure of the Harderian gland in male and female green frogs were investigated in different periods of the year. Gonadectomy, carried out when the glands are in the lowest secretory phase (September), causes degenerative changes consisting of a reduction of the rough endoplasmic reticulum, the appearance of autolysosomes, and an increase of nuclear heterochromatin. These effects can be prevented by testosterone treatment. No castration effects are found during the recovery (November) and enhancement (April-May) phases of secretory activity. The results suggest that the frog Harderian gland's sensitivity to testosterone changes during the annual cycle. The androgen dependence of the Harderian gland is correlated with the presence of androgen receptors in both male and female forgs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312821
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    Electronic Resource
    Carbamylcholine-induced morphological changes and spatial dynamics of [Ca2+]c in Harderian glands of guinea pigs: calcium-dependent lipid secretion and contraction of myoepithelial cells (1993)
    Springer
    Cell & tissue research 274 (1993), S. 1-14 
    Details
    ISSN: 1432-0878
    Keywords: Harderian gland ; Ultrastructure ; Fura-2/AM digital imaging ; Calcium ion ; Carbamylcholine ; Myoepithelial cells ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To determine whether lipid-secreting cells have cytosolic Ca2+ concentration ([Ca2+]c)-related secretory mechanisms, morphological changes and intracellular calcium dynamics of Harderian glands of guinea pigs stimulated by secretagogs were studied by electron microspy and Fura-2/AM digital image analysis. Control glandular cells contained large lipid vacuoles that were bordered by multi-layered membranes. Rough-surfaced endoplasmic reticulum, mitochondria, and smooth-surfaced endoplasmic reticulum may be involved in lipid vacuole formation. Myoepithelial cells surrounded alveoli. After carbamylcholine (CCh, 10−6, 10−5, and 10−3 M) stimulation, lipid materials within the membranous structures were frequently discharged by an exocytotic mechanism. Conspicuous deformation of glandular cells caused by vigorous contraction of myoepithelial cells was observed in isolated alveoli after 10−6M CCh stimulation, whereas the deformaties of glandular tissues perfused via vessels were small even after 10−3M CCh stimulation. Connective tissue between glandular alveoli inhibited unbridled myoepithelial-cell contraction. Fura-2/AM digital imaging analysis revealed that CCh stimulation caused an increase in [Ca2+]c in isolated alveoli. The morphological reactions and changes in [Ca2+]c were prevented by atropine. When extracellular calcium ions were absent, enhanced extrusion of lipid vacuoles, myoepithelial-cell contraction, and a rise in [Ca2+]c after CCh stimulation were not observed. Nicotine and catecholamines had no effect on the secretion or on the dynamics of [Ca2+]c. It can be concluded that acetylcholine elicits exocytosis in glandular cells and contraction of the myoepithelial cells of Harderian glands, accompanied by an increase in [Ca2+]c. The dynamics of [Ca2+]c of the gland alveoli are mostly dependent on extracellular Ca2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327979
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    Electronic Resource
    Electronic Resource
    Electron-microscopic immunocytochemical study of the endocrine pancreas of sea bass (Dicentrarchus labrax) (1993)
    Springer
    Cell & tissue research 274 (1993), S. 303-314 
    Details
    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; Peptides ; Ultrastructure ; Immunogold labeling ; Sea bass ; Dicentrarchus labrax ; (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Insulin (B)-, somatostatin 25 (SST-25) (D1)-, somatostatin 14 (SST-14) (D2)-, glucagon (A)-, and glucagon PP/PYY/NPY (PP-like)-immunoreactive cells in islets of sea bass (Dicentrarchus labrax) were characterized according to their ultrastructure and immunogold labeling. Cells labeled with antisera to bonito and salmon insulin had numerous secretory granules with a small halo and round core, and a few with wide halo and round or crystalloid core. Gold particles were found throughout the granule in tissue labeled with the former but only in the core in tissue labeled with the latter. D1 cells had large granules with a medium electron-dense content and some with a darker core. D2 had smaller medium or high electron-dense secretory granules than D1 cells, located mainly in cell periphery. Glucagon-immunoreactive cells contained some granules with a polygonal core that was heavily labeled and other granules with a round core with no or hardly any labeling. Glucagon and PP-like immunoreactivity were co-localized in secretory granules, in which the gold particles showed no different distribution with the various antisera used. PYY-immunoreactive granules were also found in nerve endings. All the pancreatic endocrine cell types showing involutive characteristics are found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318749
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  • 39
    Electronic Resource
    Electronic Resource
    Cutaneous and subcutaneous sensory receptors of the hagfish Myxine glutinosa with special respect to the trigeminal system (1993)
    Springer
    Cell & tissue research 274 (1993), S. 353-366 
    Details
    ISSN: 1432-0878
    Keywords: Trigeminal nerve ; Mechanoreceptors ; Skin ; Peripheral autonomic ganglia ; Ultrastructure ; Myxine glutinosa ; Cyclostomata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The integument of the hagfish Myxine glutinosa is described with respect to the topography and the fine structural organization of the dermal and hypodermal nerve fiber plexus. Both nerve fiber plexuses contain small ganglion cells with axodendritic and axosomatic synapscs. The six barbels of the head (4 nasal and 2 oral barbels) are supplied with about 5600 afferent trigeminal nerve fibers via the right and left ophthalmic nerve. With respect to the topography of the sensory nerve terminals in the barbels different types of receptors are termed the external cuff receptor, internal cuff receptor, and perichondrial receptor. Free nerve terminals occur within the epidermal layer, especially at the tip region of the barbels and in the glassy membrane of the dermis. The hypodermal edge receptor organ extends from the ventral nasal barbel to the oral barbel. A mechanoreceptive function of the different receptor types is discussed. The innervation pattern of the barbel is similar to the innervation of the mammalian sinus hair. In this context, the barbel is a highly differentiated receptor organ able to explore the nearest surroundings with high stereognostic perception. The ganglion cells of the skin seem to represent a part of the peripheral autonomic nervous system, which is involved in the control of secretion mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318754
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  • 40
    Electronic Resource
    Electronic Resource
    Morphology and distribution of Müller cells in the retina of the toad Bufo marinus (1993)
    Springer
    Cell & tissue research 272 (1993), S. 183-192 
    Details
    ISSN: 1432-0878
    Keywords: Retina ; Müller cells ; Neuron-specific enolase ; Immunocytochemistry ; Quantitative analysis ; Ultrastructure ; Bufo marinus (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that an antibody against neuron-specific enolase (NSE) selectively labels Müller cells (MCs) in the anuran retina (Wilhelm et al. 1992). In the present study the light- and electron-microscopic morphology of MCs and their distribution were described in the retina of the toad, Bufo marinus, using the above antibody. The somata of MCs were located in the proximal part of the inner nuclear layer and were interconnected with each other by their processes. The MCs were uniformly distributed across the retina with an average density of 1500 cells/mm2. Processes of MCs encircled the somata of photoreceptor cells isolating them from each other by glial sheath, except for those of the double cones. Some of the photoreceptor pedicles remained free of glial sheath. Electron-microscopic observations confirmed that MC processes provide an extensive scaffolding across the neural retina. At the outer border of the ganglion cell layer these processes formed a non-continuous sheath. The MC processes traversed through the ganglion cell layer and spread beneath it between the neuronal somata and the underlying optic axons. These processes formed a continuous inner limiting membrane separating the optic fibre layer from the vitreous tissue. Neither astrocytic nor oligodendrocytic elements were found in the optic fibre layer. The significance of the uniform MC distribution and the functional implications of the observed pattern of MC scaffolding are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323585
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  • 41
    Electronic Resource
    Electronic Resource
    Structure of the tertiary component of the myenteric plexus in the guinea-pig small intestine (1993)
    Springer
    Cell & tissue research 272 (1993), S. 509-516 
    Details
    ISSN: 1432-0878
    Keywords: Myenteric plexus ; Enteric nervous system ; Intestine, small ; Ultrastructure ; Innervation, of intestinal muscle ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The tertiary component of the myenteric plexus consists of interlacing fine nerve fibre bundles that run between its principal ganglia and connecting nerve strands. It was revealed by zinc iodide-osmium impregnation and substance P immunohistochemistry at the light-microscope level. The plexus was situated against the inner face of the longitudinal muscle and was present along the length of the small intestine at a density that did not vary markedly from proximal to distal. Nerve bundles did not appear to be present in the longitudinal muscle as judged by light microscopy, although numberous fibre bundles were encountered within the circular muscle layer. At the ultrastructural level, nerve fibre bundles of the tertiary plexus were found in grooves formed by the innermost layer of longitudinal smooth muscle cells. In the distal parts of the small intestine, some of these nerve fibre bundles occasionally penetrated the longitudinal muscle coat. Vesiculated profiles in nerve fibre bundles of the tertiary plexus contained variable proportions of small clear and large granular vesicles; they often approached to within 50–200 nm of the longitudinal smooth muscle cells. Fibroblast-like cells lay between strands of the tertiary plexus and the circular muscle but were never intercalated between nerve fibre varicosities and the longitudinal muscle. These anatomical relationships are consistent with the tertiary plexus being the major site of neurotransmission to the longitudinal muscle of the guinea-pig small intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318557
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  • 42
    Electronic Resource
    Electronic Resource
    Effects of elastase on contractility and morphology of elastic tissue in isolated guinea pig papillary muscles (1993)
    Springer
    Heart and vessels 8 (1993), S. 71-78 
    Details
    ISSN: 1615-2573
    Keywords: Elastase ; Elastin ; Contractile tension ; Guinea pig papillary muscle ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Elastase (ELA) is an enzyme catalyzing the digestion of elastin, an essential constituent of elastic fibers. Using isolated guinea pig papillary muscles, we examined the effect of ELA (3 × 10−7 −3 × 10−4 g/ml) on resting tension (RT) and twitch tension (TT). The effects of ELA on elastic fibers located in the subendocardium were examined histologically. A relatively high concentration of ELA (3 × 10−4 g/ml) increased TT transiently, with progressive decreases in RT. In contrast, a relatively low concentration (3 × 10−5 g/ml) decreased both TT and RT straightforwardly. Much lower concentrations (3 × 10−6 −3 × 10−7 g/ml) did not reveal significant effects. The ELA-induced increases in TT were unaffected in the presence of atenolol (10−5 g/ml), ouabain (10−7M) or ryanodine (10−6M). ELA did not increase the maximum rate of rise of slow action potentials recorded using standard microelectrodes.ELA (3 × 10−5 g/ml) decreased the maximum TT obtained at optimal RT or Lmax, and decreased the slope of the ascending and descending limbs of the TT-RT relation curve (Frank-Starling's). Electronmicroscopic findings revealed that subendocardial elastin was mostly digested at ELA concentrations of 3 × 10−5 −3 × 10−4 g/ml. These findings suggest that the decrease of RT by ELA may be, at least in part, caused by a decomposition of the elastic fibers. On the other hand, the increase of TT by ELA could not be attributed to a release of endogenous catecholamine, an inhibition of Na+, K+-pump, a release of Ca2+ from sarcoplasmic reticulum, or an increase of slow inward current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01744386
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    Electronic Resource
    Electronic Resource
    Sub-cellular distribution of nitrogen compounds inAzolla andAnabaena by ESI and EELS analysis (1993)
    Springer
    Protoplasma 173 (1993), S. 158-169 
    Details
    ISSN: 1615-6102
    Keywords: Azolla-Anabaena symbiosis ; Ultrastructure ; Nitrogen distribution ; Electron spectroscopic imaging ; Electron energy loss spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The sub-cellular localization of some nitrogen compounds within the leaf cavities ofAzolla filiculoides Lam. was obtained by means of electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS). The analyses were performed on ultrathin unstained sections of differentAzolla leaf cavities which contain epidermal hairs,Anabaena azollae Strasb. and bacteria. Net nitrogen distributions were visualized by image analysis, and nitrogen peaks were evidenced in spectra recorded in the same areas. Different distributions of nitrogen compounds were observed within the leaf cavities along the stem, in particular inside the epidermal hairs ofAzolla and the vegetative cells and heterocysts ofA. azollae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379004
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  • 44
    Electronic Resource
    Electronic Resource
    Effect of cytochalasin A on actin distribution in the fission yeastSchizosaccharomyces pombe studied by fluorescent and electron microscopy (1993)
    Springer
    Protoplasma 176 (1993), S. 24-32 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytoskeleton ; Schizosaccharomyces pombe ; Freeze substitution ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Actin distribution and ultrastructure of the fission yeastSchizosaccharomyces pombe treated with cytochalasin A (CA) were investigated by fluorescence microscopy using rhodamine-conjugated phalloidin (rh-ph) and freeze substitution electron microscopy. Among the cytochalasins tested, CA was most effective and at 5 μg/ ml inhibited the appearance of the actin ring at the cell equator at the stage prior to septum formation and the accumulation of actin dots at the septum-forming site both in wild-type cells and the mutantcdc 11, which is defective in septum formation at restrictive temperature. Freeze substitution electron microscopy of CA-treated cells revealed the displacement and morphological alteration of cytoplasmic vesicles and dictyosomes within 30 min and the appearance of dense bodies in the cytoplasm. A sub-population of cytoplasmic vesicles and dictyosomes were insensitive to CA and maintained their original structure. An electron less dense layer containing filamentous material was noted beneath the plasma membrane and thought to be the area of heavy actin patches stained with rh-ph at the cells ends. These results suggest that CA disrupted an actin network that normally maintains the organization of the secretory pathway involving dictyosomes and vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378936
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  • 45
    Electronic Resource
    Electronic Resource
    Membrane coatings on the generative cell surface of freeze-substituted monocotyledon pollen (1993)
    Springer
    Protoplasma 176 (1993), S. 84-88 
    Details
    ISSN: 1615-6102
    Keywords: Pollen (high-pressure freezing) ; Freeze-substitution ; Generative cell ; Plasma membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary High-pressure freezing/freeze-substitution/TEM were employed for studying plasma membrane coatings in mature pollen grains. Data are presented on 6 species belonging to 4 not closely related orders. Two sorts of coatings were observed at the cytoplasmic face of the vegetative plasma membrane bordering the generative cell: (i) A dense, uniform layer with an average thickness of 10 nm (“fluffy coating”). (ii) “Strip-shaped projections” protruding rectangularly into the vegetative cytoplasm. They are 25 to 35 nm in height and set at a constant distance of about 30 nm from each other. Their maximum length, estimated from grazing sections, is about 400 nm. This is the first description of periodically arranged plasma membrane protrusions in freeze-substituted plant cells. Both kinds of membrane coatings are species-and age-dependent features. Especially “strip-shaped projections” are frequently intimately associated with polymorphic endoplasmic reticulum surrounding the generative cell, a hitherto unreported pattern. It is presumed that “strip-shaped projections” are similar to, or even identical with, “ordered ridges” observed in freeze-fracturedPhoenix dactylifera pollen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378942
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  • 46
    Electronic Resource
    Electronic Resource
    The generative cell and its close association with the endoplasmic reticulum of the vegetative cell in pollen ofCyrtandra pendula (Gesneriaceae) (1993)
    Springer
    Protoplasma 177 (1993), S. 73-81 
    Details
    ISSN: 1615-6102
    Keywords: Cyrtandra pendula ; Generative cell ; Endoplasmic reticulum ; Pollen grain ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the generative cell (GC) was examined in the bicellular pollen ofCyrtandra pendula. The essential stages are: (1) GC attached to the inline, (2) GC detached and spheroidal in shape, (3) GC mature and elongated. Cisternae of the endoplasmic reticulum (ER) of the vegetative cell are in close contact with the GC at all stages of development. In stages (1) and (2) the entire, slightly undulated surface of the GC is surrounded by tightly appressed, single ER tubules or short stacks. In mature pollen grains (stage 3) the shape of the GC as well as the arrangement of the surrounding ER changes conspicuously. The GC is now spindleshaped and its surface is wrinkled. An ER tubule is present in each invagination. These ER tubules form a cage-like framework around the GC. In the cytoplasm of the generative cell, 6 to 7 microtubular bundles with longitudinal orientation can be observed. They seem to be responsible for maintaining the elongate shape of the GC. During all stages of development vegetative ER cisternae are the only elements intimately associated with the GC wall. This feature indicates that the ER may contribute to the formation of the undulated outer shape of the GC. Also discussed is the possibility that energy-carrying substances are conveyed into the GC through the channels of ER.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403401
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  • 47
    Electronic Resource
    Electronic Resource
    Microspore development inBrassica napus and the effect of high temperature on division in vivo and in vitro (1993)
    Springer
    Protoplasma 172 (1993), S. 154-165 
    Details
    ISSN: 1615-6102
    Keywords: Brassica napus ; Cell division ; High temperature ; Microspore ; Embryogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Brassica napus cv. Topas microspores isolated and cultured near the first pollen mitosis and subjected to a heat treatment develop into haploid embryos at a frequency of about 20%. In order to obtain a greater understanding of the induction process and embryogenesis, transmission electron microscopy was used to study the development of pollen from the mid-uninucleate to the bicellular microspore stage. The effect of 24 h of high temperature (32.5 °C) on microspore development was examined by heat treating microspore cultures or entire plants. Mid-uninucleate microspores contained small vacuoles. Late-uninucleate vacuolate microspores contained a large vacuole. The large vacuole of the vacuolate stage was fragmented into numerous small vacuoles in the late-uninucleate stage. The late-uninucleate stage contained an increased number of ribosomes, a pollen coat covering the exine and a laterally positioned nucleus. Prior to the first pollen mitosis the nucleus of the lateuninucleate microspore appeared to be appressed to the plasma membrane; numerous perinuclear microtubules were observed. Microspores developing into pollen divided asymmetrically to form a large vegetative cell with amyloplasts and a small generative cell without plastids. The cells were separated by a lens-shaped cell wall which later diminished. At the late-bicellular stage the generative cell was observed within the vegetative cell. Starch and lipid reserves were present in the vegetative cell and the rough endoplasmic reticulum and Golgi were abundant. The microspore isolation procedure removed the pollen coat, but did not redistribute or alter the morphology of the organelles. Microspores cultured at 25 °C for 24 h resembled late-bicellular microspores except more starch and a thicker intine were present. A more equal division of microspores occurred during the 24 h heat treatment (32.5 °C) of the entire plant or of cultures. A planar wall separated the cells of the bicellular microspores. Both daughter cells contained plastids and the nuclei were of similar size. Cultured embryogenie microspores contained electron-dense deposits at the plasma membrane/cell wall interface, vesicle-like structures in the cell walls and organelle-free regions in the cytoplasm. The results are related to embryogenesis and a possible mechanism of induction is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379373
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  • 48
    Electronic Resource
    Electronic Resource
    Early events in division of the generative cell ofOrnithogalum virens (1993)
    Springer
    Protoplasma 172 (1993), S. 77-83 
    Details
    ISSN: 1615-6102
    Keywords: Ornithogalum virens ; Generative cell ; Mitosis ; Pollen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ornithogalum virens is a bicellular pollen species. In mature pollen, the generative nucleus is at advanced prophase. Mitosis of the generative cell is resumed just after pollen rehydration and prometaphase occurs within 10 min of germination. Prometaphase is manifested by nuclear envelope breakdown and the appearance of spindle microtubules in the nucleoplasm region. At this stage the number of cytoplasmic microtubules located in the generative cell periphery appears to decrease. Endoplasmic reticulum-like cisternae originating from the nuclear envelope tend to be spaced around the chromosomes, outside the area of the forming mitotic spindle. Some also begin to penetrate the spindle area. The results are discussed in terms of the generative cell cycle in bicellular pollen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379365
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  • 49
    Electronic Resource
    Electronic Resource
    Ultrastructure of transfer cells in spontaneous nodules of alfalfa (Medicago sativa) (1993)
    Springer
    Protoplasma 172 (1993), S. 64-76 
    Details
    ISSN: 1615-6102
    Keywords: Alfalfa ; Spontaneous nodules ; Development ; Rhizobium meliloti ; Transfer cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spontaneous nodules were formed on the primary roots of alfalfa plants in the absence ofRhizobium. Histologically, these white single-to-multilobed structures showed nodule meristems, cortex, endodermis, central zone, and vascular strands. Nodules were devoid of bacteria and infection threads. Instead, the larger cells were completely filled with many starch grains while smaller cells had very few or none. Xylem parenchyma and phloem companion cells exhibited long, filiform and branched wall ingrowths. The characteristic features of both types of transfer cells were polarity of wall ingrowths, high cytoplasmic density, numerous mitochondria, abundant ribosomes, well-developed nucleus and nucleolus, and vesicles originated from rough endoplasmic reticulum. These results were compared with normal nodules induced byRhizobium. Our results suggest that xylem parenchyma and phloem companion transfer cells are active and probably involved in the short distance transport of solutes in and out of spontaneous nodules. Since younger nodules showed short, papillate, and unbranched wall ingrowths, and older tissue showed elongated, filiform and branched wall ingrowths, the development of wall ingrowths seemed to be gradual rather then abrupt. The occurrence of both type-A and -B wall ingrowths suggests that phloem companion transfer cells may be active in loading and unloading of sieve elements. Since there were no symbiotic bacteria and thus no fixed nitrogen, it is tempting to speculate that xylem parenchyma transfer cells may be re-transporting accumulated carbon from starch grains to the rest of the plant body by loading xylem vessels. Fusion of ER-originated vesicles with wall ingrowth membrane indicated the involvement of ER in the membrane formation for elongating wall ingrowths. Since transfer cells were a characteristic feature of both spontaneous andRhizobium-induced nodules, their occurrence and development is controlled by the genetic make-up of alfalfa plant and not by a physiological source or sink emanating from symbiotic bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379364
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  • 50
    Electronic Resource
    Electronic Resource
    The effects of abscisic acid on the maturation ofBrassica napus somatic embryos (1993)
    Springer
    Protoplasma 174 (1993), S. 147-157 
    Details
    ISSN: 1615-6102
    Keywords: Abscisic acid ; Brassica napus ; Embryo maturation ; Reserves metabolism ; Somatic embryos ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A comparison of embryos, cultured for increasing periods of time with and without abscisic acid (ABA), was undertaken to investigate, at the ultrastructural level, the influence of this growth regulator on the maturation of rapeseed (Brassica napus) somatic embryos. In the absence of ABA, the embryos germinated precociously while lipid bodies (LB), which were not numerous, soon degraded, as revealed by a depletion process associated with the appearance of morphologically mature glyoxysomes and an increase in the number of mitochondria. Moreover, a lack of protein bodies indicated that storage protein accumulation was not initiated under these conditions. On the contrary, the addition of ABA (10 μM) induced marked modification of embryo metabolism. Indeed, ABA completely prevented precocious embryo germination and inhibited lipid reserve catabolism. Moreover, the formation of small vacuoles and proliferation of rough endoplasmic reticulum in their vicinity suggested the onset of storage protein accumulation. After 15 days in the presence of ABA, the embryos contained abundant lipid and protein bodies. Nevertheless, these somatic embryos were not exactly the same as their mature zygotic counterparts since differences were found in chloroplasts, amyloplasts, and nuclear structures. These observations suggest that additional factors might be required to obtain fully mature somatic embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379047
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  • 51
    Electronic Resource
    Electronic Resource
    Skeletal muscle damage during tourniquet-induced ischaemia (1993)
    Springer
    European journal of applied physiology 67 (1993), S. 342-347 
    Details
    ISSN: 1439-6327
    Keywords: Tourniquet ; Ischaemia ; Skeletal muscle ; Damage ; Lysosomes ; Oedema ; Capillaries ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle biopsies from the vastus lateralis muscle of patients who had undergone anterior cruciate ligament surgery under conditions of tourniquet-induced ischaemia were examined under the electron microscope at different periods of time up to 90 min of ischaemia. The severity of the alterations in ultrastructure appeared to depend on the period of ischaemia. The pathological changes consisted of accumulation of lysosomes, persistent intrafibre oedema, and some extracellular oedema. Signs of fibre necrosis were found after 90 min of ischaemia. Capillary ultrastructure was only altered with regard to some swelling of the endothelium and marked thickening of the basement membrane. It was concluded that skeletal muscle could be severely affected even during relatively short periods of ischaemia, which might facilitate the development of muscle atrophy during immobilization after orthopaedic surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357633
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  • 52
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    Electronic Resource
    Ultrastructural changes in salivary glands after different adrenergic and cholinergic stimulations (1993)
    Springer
    European archives of oto-rhino-laryngology and head & neck 250 (1993), S. 33-39 
    Details
    ISSN: 1434-4726
    Keywords: Rat salivary gland ; Ultrastructure ; Adrenergic stimulation ; Cholinergic stimulation ; Sialagogues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have compared four different sialagogues and their degranulating effect on serous and mucous cells, and their long-term effects. From this and earlier experiments, even within the groups of α- and β-adrenergic agents used, the effects varied on the serous and mucous cells. Previous studies have shown that cyclocytidine effectively degranulates serous cells without signs of cellular damage, while carbachol predominantly affects mucous acinar cells but gives early rise to permanent gland damage. Noradrenaline affects both serous and mucous cells, predominantly affecting serous cells with initial mitochondrial damage. Clonidine partially depletes both serous and mucous cells of their granules, producing permanent cellular damage. One month after a single injection of cyclocytidine the early findings described had disappeared. Carbachol showed permanent damage to salivary gland parenchyma, and both noradrenaline and clonidine demonstrated a long-term effect on acinar mucinous cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00176946
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    Synthese, Struktur und Umlagerung von Chlorbis(2,4,6-tri-tert-butylphenyl)gallan (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2255-2257 
    Details
    ISSN: 0009-2940
    Keywords: Gallane, chlorobis(supermesityl) ; Rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structure, and Rearrangement of Chlorobis(2,4,6-tri-tert-butylphenyl)gallaneThe title compound 1 is easily obtained from GaCl3 and 2 equvialents of supermesityllithium. According to an X-ray structure analysis one of the supermesityl rings shows a large deviation from planarity. Heating of 1 in vacuo gives mainly two products: an isomer of 1 in which one of the supermesityl groups is bound to Ga by one of its tert-butyl groups (2) and a benzo[b]gallolane (3) formed by elimination of HCl, X-ray structure analyses and full NMR (1H, 13C) data are provided for 1 and 2, MS and characteristic NMR (1H, 13C) data for 3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261014
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260101
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    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXX. Insertions- und Additions-Reaktionen an Diphosphamanganacyclopropanen mit aktivierten Alkinen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 23-29 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphamanganacyclopropanes ; Alkyne insertion ; Alkyne addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-;Containing Heterocycles: Preparation, Properties, Reactions, LXXX.  -  Insertion and Addition Reactions on Diphosphamanganacyclopropanes with Activated AlkynesThe thermally and kinetically stable diphosphamanganabicyclooctadienones 3a  -  e [R2 = tBu: R1 = iPr (a), nPr (b), Ph (c); R2 = Cy: R1 = nPr (d), Ph (e)] are obtained by the reaction of the alkyne (CCO2Me)2 with the diphosphamanganacyclopropanes (OC)4Mn-PR12=PR2 (2a  -  e). Depending on steric factors the formation of 3a  -  e occurs in two different ways. In a first step the alkyne is inserted into the P  -  P bond of 2a  -  e to give the kinetically labile five-membered rings 1a  -  e. Subsequently another alkyne is added to the PR2 and a CO group of 1a  -  e to give 3a  -  e. In an alternative way the alkyne is added first to the PR2 and a CO group of 2a with formation of the diphosphamanganabicyclohexenone 4a. Insertion of a second alkyne into the P  -  P bond of 4a affords the bicyclooctadienone 3a. Compound 2a, 3c, and 4a have been characterized by X-ray structural analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260105
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    Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen, CXIV. Organorhenium(VII)-oxide (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 45-50 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multiple Bonds between Main Group Elements and Transition Metals, CXIV.  -  Organorhenium(VII) OxidesAlkylrhenium(VII) oxides of formulae RReO3 and RReO3 · L (L = quinuclidine) result from dirhenium heptaoxide and dialkylzinc compounds at low temperatures in THF solution. Unbranched, noncyclic organorhenium oxides prove to be less thermolabile than branched-chain derivatives, with the thermal stability decreasing with increasing chain length. Complexes with branched carbon chains normally can be isolated as 1:1 adducts of a nitrogen base, e.g. quinuclidine. A first chiral alkylmetal oxide and base-stabilized cyclopropyltrioxorhenium(VII) are also described.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260108
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    Notizen / Notes [Li2(THF)4DAD] und [DAD  -  H][ZrCl5(THF)]: Neue Strukturvarianten phenylsubstituierter 1,4-Diaza-1,3-dien-Liganden (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 57-61 
    Details
    ISSN: 0009-2940
    Keywords: Lithium compounds ; Enediamide structure ; 1,4-Diaza-1,3-diene, protonated ; Hydrogen bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [Li2(THF)4DAD] and [DAD  -  H][ZrCl5(THF)]: New Types of Phenyl-;Substituted 1,4-Diaza-1,3-diene LigandsTwo extreme situations in 1,4-diaza-1,3-diene (DAD) chemistry are described. Reaction of phenyl-substituted DAD 1a  -  c with lithium in the molecular ratio of 1:2 affords in high yield the extremely air-sensitive complexes [Li2(THF)4DAD] (2a  -  c). The structure of 2b has been determined by X-ray diffraction. Each of the Li+ ions is coordinated by the two terminal N atoms of the s-cis-configurated DAD dianion and by two molecules of THF. Protonation of ZrCl4 · DAD (3a) by HCl in THF gives the ionic complex [ZrCl5(THF)][DAD  -  H] (4), which contains a protonated [DAD  -  H]+ cation. The structure of the sterically crowded N = C  -  C = N skeleton of the [DAD  -  H]+ cation is not influenced by the positive charge and adopts the unusual Z-gauche-Z conformation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260110
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    Reaktive E = C(p-p)π-Systeme, XXXIII. Side-on-Koordination des Phosphaalkins P ≡ C  -  N(iPr)2 im 16e-Nickel(0)-Komplex Ni(CO)PCy3[PCN(iPr)2] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 63-65 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkyne, amino- ; Nickel carbonyl phosphane complex ; π Coordination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive E = C(p-p)π Systems, XXXIII.  -  Side-on Coordination of the Phosphaalkyne P ≡ C  -  N(iPr)2 in the 16e Nickel(0) Complex Ni(CO)PCy3[PCN(iPr)2]The reaction of (diisopropylamino)phosphaethyne P ≡ C  -  N(iPr)2 with the nickel complex [Ni(CO)3PCy3] - in contrast to the analogous reactions with Ni(CO)4 or Ni(CO)3PR3 (R = Me, Ph) - leads to the novel 16e nickel(0) system [Ni{η2-P ≡ C  -  N(iPr2)}(CO)PCy3] with a planar geometry of all skeleton atoms besides the methyl and cyclohexyl groups. Side-on coordination of the P ≡ C triple bond results in an increase of the PC distance to 1.665 Ȧ typical for phosphaalkenes.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260111
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  • 59
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    Zur Tautomerie von 5,5-Diphenyldihydro-4H-1,2,3-triazol-4-on und 5-Amino-4,4-diphenyl-4H-1,2,3-triazolen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 103-108 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,3-Triazol-4-ones, 3,5-dihydro-4H- ; 1,2,3-Triazoles, 5-amino-4H- ; Tautomerism ; 15N-NMR Spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tautomerism of 5,5-Diphenyldihydro-4H-1,2,3-triazol-4-one and 5-Amino-4,4-diphenyl-4H-1,2,3-triazolesMethylation of the 5-amino-4H-1,2,3-triazole 5 affords the N-methyl- (12) and the N,N-dimethylaminotriazole 13. X-ray diffraction analyses show that the tautomer 5b exists in the crystal and that 5b and 13 possess similar structures and atomic distances. Both compounds exhibit restricted rotation of the amino groups in solution. The comparison of UV, carbon-13 and nitrogen-15 spectra of the tautomeric triazoles 2 and 5 with those of the N-methyl compounds 3 and 13 demonstrates that the tautomers 2a and 5b are strongly favoured also in solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260117
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    3a,6-Dihydro-3H-imidazo[1,2-d]tetrazole aus 1- und 4-Phenacyl-1H-tetrazolium-Salzen und Ammoniak (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 129-132 
    Details
    ISSN: 0009-2940
    Keywords: 3H-Imidazo[1,2-d]tetrazoles, 3a,6-dihydro- ; Tetrazolium salts, 1,5-dialkyl(aryl)-4-phenacyl- ; reaction with ammonia ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3a,6-Dihydro-3H-imidazo[1,2-d]tetrazoles from 1- and 4-Phenacyl-1H-tetrazolium Salts and AmmoniaTreatment of the tetrazolium salts 1 with aqueous ammonia affords the novel ring system 2 (in certain cases along with the ylides 3). The structure of 2 has been confirmed by an X-ray analysis of 2a.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260120
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    Crystal Structure of the Explosive Parent Benzyne Precursor: 2-Diazoniobenzenecarboxylate Hydrate (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 243-249 
    Details
    ISSN: 0009-2940
    Keywords: Benzyne precursor ; Neighboring group interactions ; Incipient nucleophilic attack ; 2-Diazoniobenzenecarboxylate ; Calculations, ab initio, MO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the highly unstable benzyne precursor 2-diazoniobenzenecarboxylate (3) has been determined by single-crystal X-ray diffraction. The structure is discussed in comparison to ab initio results for several conformers of 3, related aromatic diazonium ions, and phenyl cation and also to crystal structures of simple diazonium ion salts and of benzoates. Structural features and characteristic distortions are related to the electron density distributions and to intra- and intermolecular interactions between the neighboring functional groups.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260133
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    Darstellung und Charakterisierung von Anthrylenmagnesium-Innerkomplexen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 225-237 
    Details
    ISSN: 0009-2940
    Keywords: Anthracene derivatives ; Magnesium anthracene inner complexes ; 13C CP/MAS NMR spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Characterization of Inner Complexes of AnthrylenemagnesiumAnthracene derivatives containing ether or amino groups in 9- or 9,10-position (1 - 10) react with magnesium to form new magnesium anthracene inner complexes (11 - 20). These complexes as well as their organic starting materials have been extensively characterized by spectroscopy and chemical means. It was found that solvent ligands which are present in all magnesium anthracene complexes known to date can be partially or totally replaced by inner complexation. For some of the new magnesium anthracene inner complexes the complex formation rates have been determined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260131
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    Reversibility of the [2 + 2] Cycloaddition of Isocyanates to Glycals (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 265-267 
    Details
    ISSN: 0009-2940
    Keywords: [2 + 2] Cycloaddition, reversible ; Glycals ; Isocyanates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [2 + 2] Cycloadducts obtained by the addition of tosyl isocyanate to glycals (10 - 13) undergo retro-addition upon heating or even at room temperature. The rate of retro-addition increases with rising temperature and polarity of the solvent.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260136
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    Synthesis and Aggregation Properties in Solution of a New Octasubstituted Copper Phthalocyanine: {2,3,9,10,16,17,23,24-Octakis-[(dioctylaminocarbonyl)methoxy]phthalocyaninato}copper(II) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 269-271 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanine, soluble ; Cation-induced phthalocyanine aggregates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the octasubstituted phthalocyanine 1, highly soluble in organic solvents, is described. Its aggregation properties in different solvents and in the presence of alkaline, alkaline earth, and ammonium salts are studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260137
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    Organometall-Oxide  -  Höhervalente Derivate der d-Metall-Säuren, 6. Tris(3,5-dimethyl-1-pyrazolyl)boranato-substituierte Alkyl(dioxo)1-, Methylenphosphoranyl(dioxo)1- und s̰1-Allyl(dioxo)1-Komplexe des Molybdäns und Wolframs (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 289-296 
    Details
    ISSN: 0009-2940
    Keywords: Oxo complexes, organometallic ; Borato, hydrotris(3,5-dimethyl-1-pyrazolyl)1-, complexes ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Oxo Complexes  -  Highervalent Derivatives of the d-Metal Acids, 6.  -  Hydrotris(3,5-dimethyl-1-pyrazolyl)borato-Substituted Alkyl(dioxo)1-, Methylenephosphoranyl(dioxo)1-, and s̰1-Allyl(dioxo) Complexes of Molybdenum and TungstenTp*MoO2Cl (1) and Tp*WO2Cl (2) [Tp* = κ31-HB(3,5-Me2pz)3] react with trimethyl aluminium to form the corresponding dioxo(methyl) complexes Tp*MO2(CH3), M=Mo (3), W (4). An X-ray crystal structure analysis of 3 is performed. The less oxidizing tungsten complex 2 is alkylated by Grignard reagents to yield alkyl complexes of the type Tp*WO2R 5-7 [R=CH2SiMe3, CH2tBu and CH2C(Me)Ph2] and the s̰1-2-methallyl complex Tp*WO2(CH2CMe=CH2) 8. Reactions of 2 with methylenephorphoranes R3P=CH2 (R=iPr, Ph) give transylidation products Tp*WO2(CHPiPr3) (9) and Tp*WO2(CH-PPh3) (10). Hydrolysis of 10 leads to a trioxotungstate [Tp*WO3]- (11), stabilized by a hydroxyphosphonium cation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260204
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    all-Homocalixarene: Carbocyclische Wirtverbindungen mit intra- und extraannularen Ligandarmen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2483-2491 
    Details
    ISSN: 0009-2940
    Keywords: Carbocycles ; Homocalixarenes ; Calixarenes, Homo- ; Large rings ; Macrocycles ; [2n]Metacyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: all-Homocalixarenes: Carbocyclic Host Compounds with Intra- and Extraannular Ligand ArmsMethoxy-substituted [2n]metacyclophanes 1-10, obtained by Müller-Röscheisen cyclization, are converted into all-homocalixarenes 11-20 with free phenolic hydroxy functions. The well-soluble cyclic pentamer 11 and octamer 14 with endo-acidic host properties are investigated with regard to guest binding. They exhibit selectivity towards alkaline earth metal ions (Ba2+) in liquid/liquid extraction studies. Some of the macrocyclic oligophenols are transformed into homocalixarenes 21-25 with intra- or extraannular oxapropionate groups. The diester 22 and the tetraester 23 are converted into carbocycles 26 and 27 with two and four free oxapropionic acid groups. Complexation properties of the oligoesters in extraction studies and log K values in water are reported. X-ray structural analyses were performed of the [6]-, [8]- and [4]- homocalixarenes 9 and 21, 14 and 23; the inclusion of solvent molecules is proven.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261123
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    Preparation and Conformational Studies of Ethylene-Bridged Calixarene-Analogous Macrocyclic Metacyclophanes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2501-2504 
    Details
    ISSN: 0009-2940
    Keywords: [(2.1)n]Metacyclophanes, hydroxy- ; Calixarenes ; Trans-tert-butylation ; Conformation ; Hydrogen bonding, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The novel macrocyclic compounds hexahydroxy[2.1.2.1.2.1]- (7b) and octahydroxy[2.1.2.1.2.1.2.1]metacyclophane (7c) have been prepared from anisole in six steps by using the tert-butyl function as a positional protective group on the aromatic ring. Base-catalyzed condensation of 1,2-bis(5-tert-butyl-2-hydroxy-phenyl)ethane (5) with formaldehyde in refluxing xylene does not afford the dimeric product, tetrahydroxy[2.1.2.1]metacyclophane 6a, but furnishes the larger macrocycles 6b and 6c in 70-90% yield. AlCl3/MeNO2-catalyzed trans-tert-butylation of 6b and 6c in toluene gives the desired metacyclophanes 7b and 7c in 60 and 80% yields, respectively, along with tert-butyltoluene 8b. The conformations of the systems such as trimer 6b and tetramers 6c, 7c have been evaluated from their dynamic 1H-NMR spectra. The tetramer 6c is fixed to form a “pleated-loop” conformation like the calix[8]arenes due to the much more stronger intramolecular hydrogen bonding among the hydroxyl groups than in the trimer 6b.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931261125
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    Stereoselectivity of the Thermally Initiated Free-Radical Chain Addition of Cyclohexane to 1-Alkynes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2493-2499 
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    ISSN: 0009-2940
    Keywords: Radicals ; Addition ; Stereoselectivity ; Alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkanes can be added to alkynes in a thermally initiated free-radical chain reaction (“ane reaction”). The addition of cyclohexane to 1-alkynes 1a-1 yields a mixture of (Z)- and (E)-2-cyclohexyl-1-alkenes 3a-1. An essential step in this reaction is the addition of cyclohexyl radicals to the alkynes to give 2-cyclohexyl-1-alkenyl radicals 2a-1 which abstract hydrogen from cyclohexane to yield the products 3a-1. The stereoselectivity of the addition has been measured in the temperature range of 160-260°C. It strongly depends on the substituent X of the radical center and varies over a range of almost four orders of magnitude from [(Z)-3a]:[(E)-3a] = 33 (X = OMe) at 160°C to [(Z)-31]:[(E)-31] = 0.012 (X = tBu) at 260°C. The stereoselectivity is further influenced by the temperature and in most cases by the concentration of the hydrogen donor cyclohexane. The reaction is discussed in terms of the stereoselectivity of the addition of cyclohexyl radicals to the alkyne, of the structure of the 1-alkenyl radical (σ and π radical, respectively), the rate of inversion in the case of σ alkenyl radicals, and the relative rates of syn and anti hydrogen transfer.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261124
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    Medium-Sized Cyclophanes, 29. Synthesis and Desulfurization of 2,11-Dithia[3]metacyclo- and 2,11-Dithia[3]paracyclo[3](4,9)pyrenophanes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2505-2511 
    Details
    ISSN: 0009-2940
    Keywords: Cyclophanes ; Benzenopyrenophane, 4,9-bridged ; Sulfones, pyrolysis of ; Photodesulfurization ; [2]Naphthaleno[2]paracyclophane, 1,5-bridged ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,11-Dithia[3]metacyclo- (14b) and 2,11-dithia[3]paracyclo[3]-(4,9)pyrenophane (14c) were obtained by the coupling reactions of 4,9-bis(chloromethyl)pyrene (12) with the corresponding bis(mercaptomethyl)benzenes (13b, c). Attempted pyrolysis of the disulfones 18b, 18c to afford [2]metacyclo- (19b) and [2]paracyclo[2](4,9)pyrenophane (19c) failed. Only the ring cleavage products 16 and 20 were obtained. The sulfur dioxide extrusion by vapor-phase pyrolysis of the corresponding disulfone 18 to the highly strained 19 clearly demonstrates the limits of these preparative ring contraction method. The photolytic desulfurization of 14c afforded the [2](1,5)naphthal-eno[2]paracyclophane analogue 21 instead of [2]paracyclo[1]-(4,9)pyrenophane 21′. The mechanism of the pyrolysis and photolysis reactions is discussed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261126
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    Flow-Vacuum Pyrolysis of Polycyclic Compounds, 6. Pyrolysis of Dibenzo [CH]8 Hydrocarbons (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2513-2517 
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    ISSN: 0009-2940
    Keywords: Dibenzo [CH]8 hydrocarbons ; Flow-vacuum pyrolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flow-vacuum pyrolysis of dibenzo [CH]8 hydrocarbons 2,3,4, and 5 are studied at 1 Torr and in the temperature range between 400 and 650°C. The following new transformations have been observed: 2⇆4, 2→5, 3→5, 3⇆4, 3→2, 5→11, the last three presenting analogies in the [CH]8 and/or benzo [CH]8 series. A reaction mechanism is suggested.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261127
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    On the Reaction of 1-Aza-2-azoniaallene Salts with Carbodiimides (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2519-2524 
    Details
    ISSN: 0009-2940
    Keywords: 1-Aza-2-azoniaallene cations ; Carbodiimides ; 1H-1,2,4-Triazolium salts ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aza-2-azoniaallene cations 3, prepared in situ from geminal (chloroalkyl)azo compounds 2, react with carbodiimides 4 to give 4,5-dihydro-5-imino-1H-1,2,4-triazolium salts 7. An X-ray structural analysis was carried out for 71. According to AM1 calculations the cycloaddition of carbodiimides to 1-aza-2-azoniaallene cations occurs in a nonconcerted manner via cyanamidium cations 5 as intermediates. Hetero-Wagner-Meerwein rearrangements of the primary cycloadducts 6 provide the final products 7.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261128
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  • 72
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    Organophosphorverbindungen, 73. Der Tri-tert-butyl-2-cyclopropen-1-yl-Rest als kinetisch stabilisierende Gruppe für 1-Aza-3-phosphaallene (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2525-2530 
    Details
    ISSN: 0009-2940
    Keywords: Phosphanes, cyclopropenyl- ; Phosphaalkenes, cyclopropenyl ; Shifts, [1,3]-silyl and [1,3]-H ; 1-Aza-3-phosphaallenes ; Cyclopropenyl substituents ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 73[1]. - The Tri-tert-butyl-2-cyclopropen-1-yl Substituent as Kinetically Stabilizing Group for 1-Aza-3-phosphaallenes[2]The cyclopropenylphosphane 5 reacts with the isocyanates 6a-g to form the phosphaalkenes 7a-g. An analogous transformation occurs with the same phosphane and the bifunctional isocyanates 8a, b (→ 9a, b). In contrast, the reaction 5 + 6h ends at the stage of the tautomers 11h ⇆ 12h. Methanolysis of 7b and of 11h ⇆ 12h leads to the carbamoyl-cyclopropenylphosphanes 14a and b, respectively. Sodium hydroxide-catalyzed elimination of hexamethyldisiloxane from 7b, g and the tautomer mixture 11h ⇆ 12h yields the target 1-aza-3-phosphaallenes 16a-c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261129
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  • 73
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    4,5,12,13-Tetrabromo[2.2]paracyclophane - A New Bis(aryne) Equivalent (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2531-2534 
    Details
    ISSN: 0009-2940
    Keywords: [2.2]Paracyclophanes ; 1,2-Dibromoarenes ; anti-[2.2]Paracyclophanes ; Aryne generation ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2 with nBuLi at -78°C generates aryne intermediates within the aromatic rings of [2.2]paracyclophane which are trapped in Diels-Alder reactions with dienes like furan, 1,9-diphenylisobenzofuran, or cyclopentadiene. Reductive deoxygenation with low-valent titanium reagents or TMSI converts the adducts of furan and isobenzofuran into anti-[2.2]paracyclophanes 4 and 5, respectively. The reaction of two aryne intermediates with [2.2](2,5)furanophane (7) yields 8 with three [2.2]paracyclophane units arranged in a stair-like fashion; yet, in this compound the highly shielded oxygen atoms cannot be removed anymore by reduction.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261130
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  • 74
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    Coordinated 1-Aza-1,3-butadienes: Stable Intermediates in the Formation of Pyridines from [(β-Aminoethenyl)carbene]chromium Complexes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2535-2541 
    Details
    ISSN: 0009-2940
    Keywords: Chromium, (β-aminoethenyl)carbene complexes ; 1-Aza-1,3-butadienes, coordinated ; Pyridines, cycloaddition with alkynes ; Chelated chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(β-Aminoethenyl)carbene]chromium complexes 3a-c rearrange to coordinated 1-aza-1,3-butadienes 6a-c, which undergo cycloadditions with alkynes 7a, c to pyridines 9a, 10a-c.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261131
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  • 75
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    A Soluble Benzodifluoranthene Derivative by Dehydration of an Oxygen-Bridged Precursor (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2543-2546 
    Details
    ISSN: 0009-2940
    Keywords: Multicyclic aromatic hydrocarbons, dehydration to ; Multicyclic aromatic hydrocarbons, solubility of ; Benzodifluoranthene derivative ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and characterization of the alkyl chain-substituted benzodifluoranthene 6 are described. The final synthetic step involves an acid-promoted dehydration whose conversion is determined to be quantitative. The solubilities of compounds 4e, 5, and 6 are qualitatively correlated with structural features. The molecular structure of 6 in the crystal is elucidated by an X-ray structure analysis.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261132
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  • 76
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    Synthese mittlerer und großer Ringe, XXXIV. Stereoselektive Synthese überbrückter und verzweigter Methyl-desoxyfuranoside aus 3,6-Hexanooxepin-4,5-dicarbonsäure-dimethylester (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2547-2551 
    Details
    ISSN: 0009-2940
    Keywords: Furanosides, methyl ; Photochemistry ; Stereoselective reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Medium and Large Rings, XXXIV[1,2]. - Stereoselective Synthesis of Bridged and Branched Methyl Deoxyfuranosides from Dimethyl 3,6-Hexanooxepine-4,5-dicarboxylateThe stereoselective synthesis of the bridged methyl furanosides 4-8 with four, five, and six stereogenic centers is described. The reaction sequence starts with the addition of methanol to the oxepine 1. The photochemical electrocyclic ring closure of 2 gives the cyclobutene 3. Ruthenium tetraoxide oxidation of 3 leads to the title compound 4 that is further converted to 5-8 by stereoselective reductions.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261133
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  • 77
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    Synthese, Struktur und Reaktivität von Diphosphiranen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 645-648 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphiranes, molecular structure of ; 1,2-Diphospha-2-propene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structure, and Reactivity of DiphosphiranesThe 1,1-diamino-1,2-diphospha-2-propen (2,6-Me2C5H8N)2P - P=C(SiMe3)2 (3) is obtained by treatment of bis(2,6-dimethyl-piperidino)(trimethylsilyl)phosphane (1) with [bis(trimethylsilyl)methylene]chlorophosphane (2). Compound 3 readily undergoes thermally isomerization to the diphosphirane 2,6- Nucleophilic substitution of the P1-chloro function of 1-chloro-2-(diisopropylamino)1-3,3-bis(trimethylsilyl)diphosphirane (6) leads to alkyl, amino, phosphanyl, and arsanyl derivatives 7a - d. The corresponding hydrogen derivative 7e is formed by reduction of 6 with tri-n1-butylstannane. The molecular structure of 7c as well as the NMR data of the diphosphiranes are discussed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260314
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    Übergangsmetall-Stannyl-Komplexe, 7. Darstellung von Carben-Komplexen (π1-Aromat)(CO)2CrCR2 durch Umsetzung der anionischen Stannyl-Komplexe [(π1-Aromat)(CO)2CrSnPh3]- mit R2CX2 oder [R2CX]Y (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 657-664 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes ; Stannyl complexes ; Chromium complexes ; Anionic complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Stannyl Complexes, 7[1]. - Preparation of Carbene Complexes (π1-Arene)(CO)2CrCR2 by the Reaction of the Anionic Stannyl Complexes [(π1-Arene)(CO)2CrSnPh3]- with R2CX2 or [R2CX]YCarbene complexes (π1-arene)(CO)2Cr=CR2 are formed in substitution/elimination reactions from the anionic stannyl complexes K[(π1-arene)(CO)2CrSnPh3] [π1-arene=C6H6 (1a), 1,3,5-Me3C6H3 (1b), 1,2,4,5-Me4C6H2 (1c)] C6Me6 (1d) and organic dihalides R2CX2 containing activated C - X bonds or ionic halides [R2CX]Y. Bis(stannyl) complexes (π1-arene)(CO)2Cr(SnPh3)2 (3) and hydrido(stannyl)complexes (π1-arene)(CO)2Cr(H)SnPh3 are formed as byproducts due to the reaction of the eliminated Ph3SnCl with the anionic starting complexes or electron transfer reactions, respectively. The portion and ratio of the byproducts is largely influenced by the steric properties of both the (π1-arene)(CO)2Cr fragment and the organic halide. Pyridinylidene complexes 2) are only obtained from 2-chloro-N1-methylpyridinium tetrafluoroborat with 1a - c, but not with 1d. With the sterically less demanding halides [R2N=C(H)Cl]Cl [NR2=NMe2, (n=3, 4)] or 3,3-dichloro-1,2-diphenylcyclopropene the carbene complexes (π1-arene)(CO)2Cr=C(H)NR2 or are obtained with all employed π1-arene ligands.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260316
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    Vinyliden-Übergangsmetallkomplexe, XXII. Alkin-, Alkinyl(hydrido)1-, Vinyliden-und Vinylvinyliden-Komplexe des Rhodiums aus OH-, NH2- und Cl-funktionalisierten Alkinen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 669-678 
    Details
    ISSN: 0009-2940
    Keywords: Vinylidenerhodium complexes, γ1-functionalized, generation from alkynols and their derivatives ; (Vinylvinylidene)1- and allenylidenerhodium complexes, formation by HX elimination ; Alkynyl(hydrido)1- rhodium(III) complexes, preparation from alkyne or vinylidene precursors ; Rhodium complexes, cyclopentadienyl, with vinylvinylidene ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vinylidene Transition Metal Complexes, XXII[1]. - Alkyne, Alkynyl(hydrido)1-, Vinylidene-, and Vinylvinylidene Complexes of Rhodium from OH-, NH2-, and Cl-Functionalized Alkynes
    Notes: The reaction of [RhCl(PiPr3)2]n with γ1-functionalized 1-alkynes HC≡C-CRR′X (X=OH, OMe, Cl, NH2) at room temperature leads to the formation of either alkyne-, alkynyl(hydrido)1-, or vinylidenerhodium complexes. The alkyne and alkynyl-(hydrido) derivatives rearrange thermally or in the presence of deactivated Al2O3 to the isomeric vinylidenerhodium compounds in almost quantitative yield. On treatment of the γ1-functionalized vinylidenerhodium complexes trans-[RhCl(=C=CH-CRR′X)(PiPr3)2] with Al2O3 or traces of acids, elimination of HX occurs and (for R=H, CH3; R′=CH3; X=OH, Cl, NH2) the (vinylvinylidene)rhodium compounds trans-[RhCl(=C=CH-CR=CH2)(PiPr3)2] are formed. In contrast, the reaction of trans-[RhCl(=C=CHCPh2OH)(PiPr3)2] with either Al2O3 or acid gives the allenylidene complex trans-[RhCl(=C=C=CPh2)(PiPr3)2]. The 1-hexyne derivatives HC≡C[CH2]3CH2X (X=OH, Cl) react with [RhCl(PiPr3)2]n to give alkyne-, alkynyl(hydrido)1-, and vinylidenerhodium compounds; attempts to form the cyclic vinylidene complex trans- by HX elimination from trans-[RhCl(=C=C=CH[CH2]3CH2X)(PiPr3)2] (X=OH, Cl) failed. The half-sandwich-type (vinylvinylidene)rhodium compounds [C5H5Rh(=C=CH-CR=CH2)(PiPr3)] (R=H, Me) are obtained from [RhH(C≡C-CR=CH2)Cl(py)(PiPr3)2] and NaC5H5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260318
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    (Bicyclo[3.2.0]hepta-1,3-dienyl)cobalt(I) Complexes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 713-724 
    Details
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.0]hepta-1,3-dienyl complexes ; Calculations, semiempirical ; Alkyne trimerization ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three isomeric bicyclo[3.2.0]heptadienes 1 - 3 are compared by semiempirical calculations. Experimental attempts directed to the synthesis of derivatives of 1 are described. The synthesis, properties and some reactions of (η51-bicyclo[3.2.0]hepta-1,3-dienyl)(η41-cycloocta-1,5-diene)cobalt(I) (22), including an X-ray crystal structure determination of the reaction product with diphenylethyne, the tetraphenylcyclobutadiene complex 30, are presented.
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    URL: http://dx.doi.org/10.1002/cber.19931260323
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    Synthese und Struktur von Phosphiren-Iminen und Iminophosphaspiro[2.2]pentanen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 649-655 
    Details
    ISSN: 0009-2940
    Keywords: λ51-Phosphirenes, imino- ; λ51-Phosphaspiro[2.2]pentanes, imino ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Phosphirene Imines and Iminophosphaspiro[2.2]pentanesThe reaction of the iminophosphanes R1P=NR2=[1, R2=2,4,6-tBu3C6H2;R1=Me (a) Et (b), PhCH=CH (c), Cl (d); R2=tBu, R1=Et3C (e)] with the alkynes R3C ≡ CR4 [2, R3=R4=Ph (a), CO2Me (b)] affords the corresponding phosphirene imines 3a - g. A [2 + 1] cycloadduct 3h is also formed in the reaction of the alkyne 2c (R3=H, R4=Ph) with 1d, while in the case of 1b the 1,2-addition product 4 is obtained. As demonstrated by the [2 + 1] cycloaddition reaction of the P1-alkylated iminophosphanes 1a, b with methylene-cyclopropanes 5a, b, the formation of the iminophosphaspiro[2.2]pentanes 6a, b is observed. The structures of the P/C heterocycles 3a, b and 6b have been determined by NMR spectroscopy and X-ray analysis.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260315
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    Schwefel(IV)1-Verbindungen als Liganden, 19. Kationische Ruthenium-Sulfen-Komplexe: Synthese und Reaktionen. Kristallstrukturanalyse von [Cp*(Me3P)2Ru(CH2=SO2)]PF6 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 679-684 
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    ISSN: 0009-2940
    Keywords: Ruthenium complexes ; Sulfur dioxide complexes ; Sulfene complexes ; Nucleophilic addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfur(IV) Compounds as Ligands, 19[1]. - Cationic Ruthenium-Sulfene Complexes: Synthesis and Reactions. Crystal Structure Analysis of [Cp*(Me3P)2Ru(CH2=SO2)]PF6Methylene addition to coordinated sulfur dioxide yields the novel η2(C, S) sulfene complexes [Cp(dppm)Ru(CHR=SO2)]PF6 (R=H:3, Me: 4) and [Cp*(Me3P)2Ru(CH2=SO2)]PF6 (5). An X-ray structure determination of 5 reveals a relatively short C - S bond (167.5 pm). The sulfene complexes are powerful carbon electrophiles as shown by the rapid addition of halides, pseudohalides, amines, including „nonnucleophiles“ such as ethyldiisopropylamine and DBU, and phosphanes to 3. The regioselectivity of the reaction of 3 with enamines is opposite to that of free sulfene, i.e. coordination of the sulfene to ruthenium effects umpolung.
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    URL: http://dx.doi.org/10.1002/cber.19931260319
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    Monofunktionelle tetraedrische Zink-Komplexe L3ZnX [L3=Tris(pyrazolyl)borat] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 685-694 
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    ISSN: 0009-2940
    Keywords: Zinc complexes ; Tris(pyrazolyl)borat ligands ; Reactivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monofunctional Tetrahedral Zinc Complexes L3ZnX [L3=Tris(pyrazolyl)borate]The pyrazolyl borates K[HBpz3*] (abbreviated KL3, pz*=3-phenyl-, 3-tolyl-, 3-anisyl-3,5-diphenyl pyrazolyl) react with zinc salts ZnX2 (X=Cl, Br, I, NO3) to form the mononuclear neutral tetrahedral zinc complexes L3ZnX (1 - 4). The corresponding alkylzinc complexes L3ZnR (5 - 8; R=Me, Et, tBu, Ph) result either from L3ZnCl and LiR or from ZnEt2 and KL3. These alkylzinc compounds are remarkably stable towards oxidation and hydrolysis. For specific cases the reaction of L3ZnR with carboxylic acids is found to yield the carboxylates L3ZnOCOR (9, 10), and likewise with thioacetic acid to yield the thioacetates L3ZnSCOMe (11). Facile cleavage of L3ZnR with thiols and selenophenol produces the thiolates L3ZnSR (12, 13) and the selenolates L3ZnSePh (14). The complexes L3ZntBu which are the most reactive of the alkylzinc compounds are cleaved by H2O, H2S, NH3 and various OH and NH compounds with formation of the bis(ligand) complexes Zn(L3)2 (15). Crystal structure determinations of one L3ZnX complex each for X=NO3 (4a), CH3 (5a), SCOMe (11a), and SEt (12a) confirm the nature of the compounds and the relation of 4a and 12a to the active centers of zinc-containing enzymes.
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    URL: http://dx.doi.org/10.1002/cber.19931260320
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    Nucleophile Singulett-Carbene in der [4 + 1]1-Cycloaddition mit 1,2,4,5-Tetrazinen: Eine neue Isopyrazol-Synthese (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 733-738 
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    ISSN: 0009-2940
    Keywords: Singlet carbenes ; [4 + 1] Cycloadditions ; Isopyrazoles ; Diels-Alder reactions ; [4 + 2] Cycloreversion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic Singlet Carbenes in the [4 + 1] Cycloaddition with 1,2,4,5-Tetrazines: a New Synthesis of IsopyrazolesA series of 3,6-disubstituted 1,2,4,5-tetrazines 6, including C6H5, SCH3, SO2CH3, N(CH3)2, CF3, CO2CH3 groups, has been submitted to [4 + 1] cycloaddition with the nucleophilic singlet carbenes 4, 15, and 20, which are generated from the precursors 1, 11 and 19, resp. In all cases isopyrazoles (4H1-pyrazoles) 9, 10, 18, and 21 are isolated in good yields. They are formed in a two-step reaction sequence with the [4 + 1] cycloadducts of type 8 as intermediates which eliminate nitrogen by subsequent [4 + 2] cycloreversion. The acceptor-substituted isopyrazole 9e is characterized as an electron-deficient diene by some Diels-Alder reactions with inverse electron demand leading to the expected azo-bridged cycloadducts 23, 25, 27, 29, and 31 without acid catalysis or application of higher pressure. With cyclooctyne (32), the [4 + 2] cycloaddition is followed by a [4 + 2] cycloreversion with formation of the cyclopentacyclooctene 34.
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    URL: http://dx.doi.org/10.1002/cber.19931260325
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    Metall-π1-Komplexe von Benzolderivaten, XLI. Bis(η61-anilin)chrom: Synthese, Redoxverhalten und Brønsted-Basizität (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 399-404 
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    ISSN: 0009-2940
    Keywords: Chromium complexes ; Aniline as an η61-ligand ; Voltammetry, cyclic ; Nerst-Clark plots ; Acid dissociation constants ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal π Complexes of Benzene Derivatives, XLI[1].  -  Bis(η61-aniline)chromium: Synthesis, Redox Properties and Brønsted BasicityBis(η61-aniline)chromium (6) has been prepared by protodesilylation of its N,N,N′,N′1-tetrakis(trimethylsilyl) derivative 5, which is accessible by metal-atom ligand-vapor cocondensation (cc). Bis(η61-dimethylaniline)chromium (3) is obtained directly from cc. The couples 3+/0 and 6+/0 feature the most negative redox potentials E1/2 ever reported for bis(arene)1-metal complexes. According to EPR spectroscopy, applied to the radical cations 3+· and 6+· the site of oxidation is largely localized on the metal. The pH dependence of E1/2 is cast in Nerst-Clark plots, whose breaks supply the pKs values of the mono-and diprotonated forms of 3 and 6. η61-Coordination to CrI increases the basicity of aniline by three pK units, whereas η61-coordination to Cr1 effects a decrease by more than seven pK units. The first and second dissociation constants of the organometallic bis(ammonium) ions 3(H+)2 and 6(H+)2 differ by 2.7 pK units. This interval reflects the interaction of the two basic centers in 3 and 6 which approaches that of p1-phenylenediamine. Thus, conjugation across the bis(η61-arene)chromium unit is virtually uninhibited.
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    URL: http://dx.doi.org/10.1002/cber.19931260216
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    Bis(pentamethylcyclopentadienyl)keton und -thioketon: Kohlenstoff-Verbindungen mit präformierter Diels-Alder-Geometrie (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 415-420 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Cyclopentadiene-5-carbonyl chloride, 1,2,3,4,5-pentamethyl- ; 1,3-Cyclopentadiene-5-carbothioyl chloride, 1,2,3,4,5-pentamethyl- ; Ketone, bis(1,2,3,4,5-pentamethyl-1,3-cyclopentadien-5-yl) ; Thioketone, bis(1,2,3,4,5-pentamethyl-1,3-cyclopentadien-5-yl) ; Diels-Alder preformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(pentamethylcyclopentadienyl) Ketone and Thioketone: Carbon Compounds with Performed Diels-Alder Geometry1,2,3,4,5-Pentamethyl-1,3-cyclopentadien-5-carbonyl chloride (2) is formed in good yields by the reaction of pentamethylcyclopentadienyllithium (1) with phosgene. The corresponding carbothioyl chloride 3 is synthesized by treatment of 1 with thiophosgene. Both acyl chlorides are stable against air and moisture and difficult to attack in SN2-type reactions. Treatment of 2 and 3 with trimethyl(pentamethylcyclopentadienyl)stannane in the presence of boron trifluoride  -  ether leads to bis(1,2,3,4,5-pentamethyl-1,3-cyclopentadien-5-yl) ketone (5) and thioketone (6), respectively. Even at room temperature, 5 and 6 tend to intramolecular [4 + 2] cycloaddition reactions. X-ray crystal structure investigations of 2, 5, and 6 show the steric demand of the pentamethylcyclopentadienyl ligand and explain the untypical chemical behavior of 2 and the easy [2 + 4] cycloaddition reactions of 5 and 6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260219
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  • 87
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    Multistep Redoxsystems, LX. 1,4,5,8-Tetraoxo-1,4,5,8-tetrahydrothianthrene: Synthesis, Structure, and Spectroelectrochemical Properties (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 465-471 
    Details
    ISSN: 0009-2940
    Keywords: Thianthrene derivatives ; X-ray analysis ; MO calculation ; Cyclovoltammetry ; UV-Vis spectroelectrochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, structure, cyclovoltammetric and spectroelectrochemical data of 1,4,5,8-tetraoxo-1,4,5,8-tetrahydrothianthrene (2a) are presented. A relation between the positive partial charge at the sulfur atom and the dihedral angle at the S—S axis is discussed on the basis of semiempirical MO calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260226
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  • 88
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    Neue Beobachtungen zur Stereoselektivität von Monoiodcarben-Additionen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 499-502 
    Details
    ISSN: 0009-2940
    Keywords: Iodocarbene, addition to alkenes ; endo1-Selectivity ; Cyclooctadiene ; Cyclooctatetraene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Observations Concerning the Stereoselectivity of Monoiodocarbene AdditionsContrary to our earlier claim, CHI gives endo/exo isomer mixtures with cyclooctene. However, only endo1-iodo compounds 7, 8, 10-12 are obtained from COD and COT. Tricyclic compound 7 rearranges partially to bicyclic 9, X-ray structure determinations of 7 and 9 were performed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260229
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  • 89
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    Reaktivität s̰1-bishomoaromatischer Heterocyclen: Elektrocyclische Reaktionen und Cycloadditionen von syn- und anti1-Bishomofuran und -BishomothiophenProfessor William von E. Doering zum 75. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 485-498 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl ylides, generation from syn1-bishomofuran ; Thiocarbonyl ylides, generation from syn1-bishomothiophene ; Ylides, carbonyl and thiocarbonyl, 1,3-dipolar cycloaddition, electrocyclization, sigmatropic 1,4-hydrogen shift of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactivity of s̰1-Bishomoaromatic Heterocyles: Electrocyclic Reactions and Cycloadditions of syn- and anti1-Bishomofuran and -BishomothiopheneProfessor William von E. Doering zum 75. Geburtstag gewidmet.The title compounds syn-4a, b and anti-4a, b, synthesized by the CuCl-catalyzed reaction of homofuran 1a or homothiophene 1b with diazomethane, are very different in their thermal stability. syn-4a isomerizes to 2,3-dihydrooxepine (7a) readily at 130°C whereas the rearrangement anti-4a → 7a requires a temperature of about 370°C. A similar difference in thermal reactivity is observed between syn-4b and anti-4b. But syn-4b undergoes in addition to the rearrangement to 2,3-dihydrothiepine (7b) a dimerization (to 12?) on thermolysis in [D6]benzene solution at 140°C, whereas mainly isomerization to 9b, cis-10b, and 11 (product of the elimination of sulfur from cis-10b) occurs on thermolysis in the gas phase. The formation of 7a and 7b, respectively, is explained by the electrocyclic ring opening of syn-4a or syn-4b leading to the carbonyl ylide 5a or the thiocarbonyl ylide 5b followed by a sigmatropic 1,4 hydrogen shift. To rationalize the additional products in the thermolysis of syn-4b an electrocyclic conrotatory ring closure in 5b leading to the highly strained episulfide trans-10b is assumed to complete with the hydrogen shift. Under the reaction conditions trans-10b is unstable and either dimerizes in solution or isomerizes in the gas phase. The formation of 9b in the thermolysis of syn-4b indicates that a two-step pathway may compete with the concerted process. syn-4a, b react with various π acceptor-substituted olefins to form cycloadducts of the general type 6a, b. The cycloaddition occurs stereospecifically cis with respect to the configuration of the starting olefin and non-stereoselectively with respect to the endo/exo ratio. The kinetic analysis of the reaction of syn-4a with fumaronitrile (FN), N1-phenylmaleinimide (NPMI) or dimethyl dicyanofumarate (DCFM) shows unambiguously, that the adducts are formed by a 1,3-dipolar cycloaddition of the intermediate carbonyl ylide 5a rather than a homo-Diels-Alder reaction of syn-4a (in contrast to the cycloaddition of homofuran 1a). A comparison between the enthalpies of reactions syn-4a → 5a (ΔHR ≤ 22.4 kcal/mol) and syn-4d → 5d (ΔHR ≥ 47.5 kcal/mol) shows the carbonyl ylide to be a 1,3-diradical, highly resonance-stabilized by the heteroatom (resonance energy R.E. ≍ -25 kcal/mol).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260228
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  • 90
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    1-Sila-3-alumina-4-aluminatacyclopentan mit Al-Al-Bindung und C2Al2Si-Heterocyclus (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2637-2641 
    Details
    ISSN: 0009-2940
    Keywords: Aluminium-aluminium bond ; C2Al2Si heterocycle ; Aluminium, three- and fourfold coordinated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Sila-3-alumina-4-aluminatacyclopentane with an Al-Al Bond and a C2Al2Si HeterocycleTetrakis[bis(trimethylsilyl)methyl]dialuminium(4) (1) with an aluminium-aluminium bond reacts in the presence of tetramethylethylenediamine (TMEDA) with the sterically highly shielded bases bis(trimethylsilyl)methyllithium or bis(dimethylphosphanyl)methyllithium to yield under deprotonation of a methyl group a carbanionic species, which is stabilized by an interaction with one of the coordinatively unsaturated Al atoms. The five-membered heterocycle 5 is formed containing two Al, one Si and two C atoms. The Al-Al bond remains uncleaved. Interestingly, 5 crystallizes in different crystals with and without crystal ether, which were both characterized by crystal-structure determinations. The Al-Al bond length in 5 [264.1(2) and 266.5(3) pm, respectively] is only slightly changed in comparison to the neutral starting compound 1 (266.0 pm). Under similar conditions the sterically less demanding ethyllithium leads to a β-elimination and addition of the thereby formed LiH to one of the two Al atoms to give the recently published hydridodialuminate(5) Li(TMEDA)2+ [R2Al-AlHR2]- (2).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261211
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  • 91
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    Homo- und Hetero-Metall-Amide des Tris(tert-butylamino)methylsilans - Polycyclen und Cluster mit Li, Na, Mg, Al und Tl (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2625-2635 
    Details
    ISSN: 0009-2940
    Keywords: Amides, hetero metal ; Polycycles ; Metal clusters of thallium ; Metal nitrogen bonding ; Carbanion, stabilized by metal complexation ; Silane, tris(tert-butylamino) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homo and Hetero Metal Amides of Tris(tert-butylamino)methylsilane - Polycycles and Clusters with Li, Na, Mg, Al and TlThe hydrogen atoms attached to nitrogen in tris(tert-butyl-amino)methylsilane (1) can be substituted by metallic main-group elements in a quite general way. If 1 is treated with trimethylaluminium apart from the monosubstituted product MeSi(tBuNH)2(tBuNAlMe2) (2) the trisamide MeSi(tBuNAlMe2)3 (3) is obtained. In similar ways complete substitution of the amino hydrogen atoms in 1 yields the compounds MeSi[tBuNMgN(SiMe3)2]3 (6), [MeSi(tBuNLi)3]2 (10), and [MeSi(tBuNTl)3]2 (11), the later two being dimeric. If methyl-magnesium iodide is allowed to react with 1 the intermediate MeSi(tBuNMgI)3 (4) in some instances can be isolated as the THF adduct or may react with a further equivalent of the Grignard compound to generate the complex [MgI-(THF)5]+ [MeSi(tBuNMgI)3CH3 · THF]- (5). The aluminium compound 2 has been used to access to heterometallic amides combining aluminium and sodium as in MeSi(tBuNAlMe2)(tBuNNa)(tBuNH) (7) or magnesium and aluminium as in the dimeric compounds [MeSi(tBuNAlMe2)(tBuNH)(tBuNMgI)]2 (8) and [MeSi(tBuNAlMe2)(tBuNH)(tBuNMgMe)]2 (9). X-ray structure analyses reveal 3 (tricyclic SiN3Al3 skeleton with Al - N distances from 2.014 to 2.025 Å), 6 (tricyclic Si-N3Mg3 skeleton), and 7 [bicyclic SiN3AlNa skeleton with Na - N distances of 2.47(1) and 2.52(1) Å] to be monomeric even in the solid state. The compounds 8 and 9 (both pentacyclic with spiro magnesium atoms) form centrosymmetric dimers by Mg - I - Mg and Mg - (CH3) - Mg bridges, respectively. The dimers 10 and 11 are completely different in terms of chemical bonding: while in the lithium compound 10 a centrosymmetric polycycle is formed by principly ionic interactions of the lithium atoms with corresponding nitrogen atoms, the centrosymmetric dimer in 11 is held together by Tl - Tl bonds. The X-ray structure analysis of 5 reveals the anion containing a Mg-coordinated CH3-.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261210
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  • 92
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    Tetraindeno-Fused Cyclooctatetraene and Oligomeric Biindenyls by Oxidative Coupling of 2,2′1-Biindenyl (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 969-973 
    Details
    ISSN: 0009-2940
    Keywords: 1,1′1-Bi(2,2′1-biindenylyls) ; Carbanions ; Oxidative coupling ; Cyclooctatetraindenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithiated biindenyls 2 and 4, prepared by deprotonation of 2,2′1-biindenyl (1) and 10,11-dihydrodiindeno[1,2-b:2′,1′-d]thiophene (3) with n1-butyllithium, are oxidatively coupled to give oligomeric biindenyls (17) as well as tetraindeno-fused eight-membered rings (16, 19, 24).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260418
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  • 93
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    Zinkkomplexe von Aminosäuren und Peptiden, 2[1]. Koordination einfacher Histidin-Derivate an Zink (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2643-2648 
    Details
    ISSN: 0009-2940
    Keywords: Histidine derivatives ; Zinc complexes ; Solution equilibria ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zinc Complexes of Amino Acids and Peptides, 2[1]. - Coordination of Simple Histidine Derivatives to ZincThe bis(L-histidine)ZnCl2 complex 1 is likely to have tetrahedral ZnN2Cl2 coordination. For the compound (L-histidine)-ZnCl2 · HCl (2) a structure determination has revealed a tetrahedral ZnOCl3 coordination. Of the C-protected histidine derivatives His-OMe and His-NH2 and zinc salts of non-coordinating anions the complexes (His-OMe)2ZnX2 (3) and (His-NH2)2Zn(ClO4)2 (4) were obtained. A structure determination of (His-OMe)2Zn(BPh4)2 · H2O has revealed a ZnN4 coordination with chelating histidine units. Of the N-protected histidine derivative Nα-acetylhistidine the complexes (Ac-His)ZnX · H2O (5, X = ClO4, BF4) have been isolated which are coordination polymers in the solid state. From pH-dependent 13C-NMR studies it is concluced that in solution the imidazole N and carboxyl O are coordinated to zinc in (Ac-His)Zn and (Ac-His)2Zn units. The doubly protected histidine derivative Bz-His-OMe acts as a monodentate ligand forming the tetrahedral complexes (Bz-His-OMe)4Zn(ClO4)2 (6) and [(Bz-His-OMe)2Zn(2,9-dimethyl-o-phenanthroline)](ClO4)2 (7).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261212
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  • 94
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    Synthese und Röntgenstrukturanalyse einer neuartigen gemischtvalenten zwitterionischen Diphosphor-Fluor-Verbindung (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2653-2655 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphorus zwitterion ; Phosphorus, hexacoordinated ; Phosphorus, tetracoordinated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and X-Ray Crystal Structure Analysis of a Novel Mixed-Valent Zwitterionic Diphosphorus Fluoro CompoundThe cyclic zwitterionic λ6P,λ4P-diphosphorus compound F5P-N(Me)P+ [N(Me)C(=O)]2NMe (3), which contains a biuret system, was synthesized by the reaction of (MeNPF3)2 (1) with MeNCO (2). Compound 3 was characterized by means of 1H-, 13C-, 19F- and 31P-NMR spectroscopy, IR spectroscopy, and mass spectrometry. A single-crystal X-ray structure determination revealed the presence of two independent formula units, in which the -N(Me)PF5 side chains display widely differing conformations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261214
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  • 95
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    Metallorganische Verbindungen der Lanthanoide, 82[1]. (2,5-Di-tert-butylpyrrolyl)-Komplexe von Neodym(III), Samarium(II) und Ytterbium(II): Synthese und Röntgenstrukturanalyse von dimerem Natrium-dichlorobis(2,5-di-tert-butylpyrrolyl)(tetrahydrofuran)neodymat(III) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2657-2659 
    Details
    ISSN: 0009-2940
    Keywords: Azacyclopentadienyl complexes ; Neodymium compounds ; Samarium compounds ; Ytterbium compounds ; Lanthanoides, organo-, chlorides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Compounds of the Lanthanoids, 82[1]. - [2,5-Di-tert-butylpyrrolyl) Complexes of Neodymium(III), Samarium(II), and Ytterbium(II): Synthesis and X-Ray Structural Analysis of Dimeric Sodium Dichlorobis(2,5-di-tert-butylpyrrolyl)(tetrahydrofuran)neodymiate(III)NdCl3(THF)1,8 reacts with Na[pyr*
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261215
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  • 96
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    Ephedrine-Derived Imidazolidin-2-ones. Broad Utility Chiral Auxiliaries in Asymmetric Synthesis (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2663-2673 
    Details
    ISSN: 0009-2940
    Keywords: Imidazolidin-2-one, (4R,5S)-1,5-dimethyl-5-phenyl- or cyclohexyl- ; (-)-Ephedrine ; Stereoselective aldol ; alkylation, acylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of the readily available (4R,5S)-1,5-dimethyl-4-phenylimidazolidin-2-one (4) and its 4-cyclohexyl analogue 6 as practical, efficient chiral auxiliaries has been demonstrated. The enolate chemistry of their N-acyl derivatives exhibits features which recommend their use in asymmetric synthesis. The stereoselective boron-mediated aldol as well as alkylation and acylation results are presented. The steric control benefit derived by conversion of phenyl to cyclohexyl is highlighted.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261216
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  • 97
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    Gas-Phase Thermolysis of Pyrazolines, 2[1]. Electronic Structure and Gas-Phase Thermolysis of 4,5-Dihydro-3H-pyrazoles Studied by Photoelectron Spectroscopy, Semiempirical Quantum-Chemical Calculations, and Flash Vacuum Pyrolysis (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2675-2681 
    Details
    ISSN: 0009-2940
    Keywords: Electronic structure ; PE spectroscopy ; Gas-phase thermolysis ; 3H-Pyrazoles, 4,5-dihydro- ; 1,3,4-Oxadiazole, 2,5-dihydro- ; 1,3,4-Thiadiazole, 2,5-dihydro- ; Cyclopropanol, 2,2,3,3-tetramethyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The PE spectra of the 4,5-dihydro-3H-pyrazoles 1, 2, of 2,5-dihydro-1,3,4-oxadiazole 3, and 2,5-dihydro-1,3,4-thiadiazole 4 have been recorded. Based on HAM/3, MNDO, AM1, and PM3 calculations, the ionization potentials have been assigned to molecular orbitals. The gas-phase thermolyses of 1-4 have been studied by PE-controlled gas analysis. Extrusion of molecular nitrogen leads to reactive species which cyclize to three-membered rings of different stability. At higher temperatures and in flash vacuum pyrolysis, consecutive reactions may lead to smaller acyclic molecules. The cyclo-propanol 7, obtained by denitrogenation of 2, is thermally rather stable. Its PE spectrum has been recorded and analyzed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261217
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    Photochemical and Thermal Rearrangement of Acyl-Substituted Quinone Methides, Accessible by Dimethyldioxirane Oxidation of Benzofurans and Subsequent Valence Isomerization of the Resulting Epoxides (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2697-2699 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl-3-phenyl ; Benzofuran epoxides ; Quinone methides ; (Z/E) Photoisomerization ; Norcaradiene ; Benzocycloheptafuran ; Thermal rearrangement ; Xanthenes, 9-acetyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoisomerization of quinone methides 3 to benzocycloheptafuran 4 and the thermolysis of the latter to xanthenes 5 are reported. The quinone methides 3 are accessible by dimethyldioxirane oxidation and subsequent valence isomerization of the resulting benzofuran epoxides 2. On irradiation (λ 〉 400 nm), the quinone methides 3 rearrange by cyclization to the corresponding norcaradiene, and ring enlargement affords the benzocycloheptafurans 4. Thermolysis of the cycloheptatrienes 4 leads to the xanthenes 5, first by cycloreversion to the norcaradienes, followed by electrocyclization to the chromenes and tautomerization of the latter. The new cycloheptatrienes 4 and xanthenes 5 were fully characterized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261220
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  • 99
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    Oxidative Spaltung von Poly(o1-phenylendiselenid) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1071-1076 
    Details
    ISSN: 0009-2940
    Keywords: Selenium halogen compounds ; Poly(o1-phenylenediselenide), cleavage of ; Oxidative cleavage ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative Cleavage of Poly(o1-phenylenediselenide)Poly(o1-phenylenediselenide) is cleaved at the Se-Se bond by treatment with SOCl2 to give benzene-1,2-bis(selenenyl chloride) (2) and benzene-1,2-bis(selenium trichloride) (3), respectively. In the solid state 2 is dimerized by Se…Se bonds whereas 3 is monomeric having terminal as well as intramolecular bridging Cl atoms. Treatment of 2 with SbCl5 gives an ionic compound (4) with a dimeric cation exhibiting a weak Se—Se bond and SbCl6- as a counterion 3 reacts with W(CO)6 to give trigonal prismatic dicarbonyl bis(o1-phenylenediselenolato)tungsten (5).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260502
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  • 100
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    Enantioselektive Katalyse, IX. Neue optisch reine 3,4-Bis(phosphanyl)pyrrolidine mit Phenyl-und Anisylgruppen sowie deren Palladium-und Rhodiumkomplexe (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1091-1100 
    Details
    ISSN: 0009-2940
    Keywords: 3,4-Bis(phosphanyl)pyrrolidines ; Palladium complexes ; Rhodium complexes ; Asymmetric hydrogenation ; Phosphanes, chiral ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective Catalysis, IX[1]. - New Optically Pure 3,4-Bis(phosphanyl)pyrrolidines with Phenyl and Anisyl Groups Including Their Palladium and Rhodium ComplexesMethods for the synthesis of the diastereomeric mixture of the [P(R,S),3R,4R,P′(R,S)]1-1-(tert1-butoxycarbonyl)1-3,4-bis[(2-methoxyphenyl)phenylphosphanyl]pyrrolidines (2a, b, c) are described. For the chromatographic separation and purification of the ligand diastereomers we transformed them into the PdI21-complexes (10a, b, c). The structure of (PR,3R,4R,P′R)1-1-(tert1-butoxycarbonyl)1-3,4-bis[(2-methoxyphenyl)phenylphosphanyl]pyrrolidine-P,P′}diiodopalladium (10 b) was determined by X-ray diffraction. Treatment of the palladium complexes with KCN yielded the pure phosphanes. The rhodium complexes (11a, 11b, 11c), which can be used as catalysts in enantioselective hydrogenations, were obtained by reaction of [Rh(COD)2]BF4 with compound 2a, 2b, or 2c.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260505
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