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  • Digitale Medien  (2.055)
  • 2020-2023
  • 2015-2019
  • 1985-1989  (1.361)
  • 1975-1979  (694)
  • 1965-1969
  • 1955-1959
  • 1988  (1.361)
  • 1976  (694)
  • 1958
  • Analytical Chemistry and Spectroscopy  (1.867)
  • Electron microscopy  (188)
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Materialart
  • Digitale Medien  (2.055)
Erscheinungszeitraum
  • 2020-2023
  • 2015-2019
  • 1985-1989  (1.361)
  • 1975-1979  (694)
  • 1965-1969
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  • 1
    Digitale Medien
    Digitale Medien
    On the ultrastructure of ependymomas — A semiquantitative analysis of diagnostic criteria in 21 cases with special reference to glycogen as a marker (1988)
    Springer
    Neurosurgical review 11 (1988), S. 67-76 
    Details
    ISSN: 1437-2320
    Schlagwort(e): Electron microscopy ; ependymoma ; glycogen ; ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report our results on the ultrastructure of 21 ependymomas and establish the following diagnostic criteria: 1. Glycogen is the most frequently encountered criterion, followed by desmosomes, cilia, basal bodies and microvilli. Fifteen tumors had 3 or more of these features. 2. The allegedly typical nuclear pattern was found in only 6 cases. 3. Special ultrastructural features seen include basement membranes in a mid-thoracic ependymoma. Furthermore we propose the hypothesis that glycogen might be involved in cilia assembly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01795697
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  • 2
    Digitale Medien
    Digitale Medien
    Origin and direction of replication in mitochondrial plasmid DNAs of broad bean,Vicia faba (1988)
    Springer
    Current genetics 14 (1988), S. 163-170 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Plant mtDNA ; Electron microscopy ; Restriction enzymes ; Hairpin structures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Broad bean (Vicia faba) mitochondrial DNA (mtDNA) includes three circular plasmids: mt-plasmid 1 (1,704 ntp), mt-plasmid 2 (1,695 ntp) and mt-plasmid 3 (1,476 ntp). Partially replicated circular forms of these mt-plasmids have been observed in electron microscope preparations. Restriction enzymes that cleave either mt-plasmid 2 (but not mt-plasmids 1 and 3) or mt-plasmid 3 (but not mt-plasmids 1 and 2) were used to generate linear forms of partially replicated mt-plasmid 2 and mt-plasmid 3 molecules. Analyses of these linearized replicative intermediates, observed by electron microscopy, indicated that in both mt-plasmid 2 and mt-plasmid 3 replication originates at a specific location and proceeds in the same, single direction around the molecules. The replication origins of mt-plasmid 2 and mt-plasmid 3 map close to sequences that can fold into hairpin structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00569340
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  • 3
    Digitale Medien
    Digitale Medien
    Malignant peripheral neuroectodermal tumours of bone other than Askin's neoplasm: characterization of 14 new cases with immunohistochemistry and electron microscopy (1988)
    Springer
    Virchows Archiv 412 (1988), S. 421-430 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Neuroectodermal bone tumours ; Immunochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Peripheral neuroectodermal tumours (PNET) of bone are rare and mimick those seen in soft tissue (peripheral neuroepithelioma of soft tissue). Their differential diagnosis from Ewing's sarcoma (Es) is extremely difficult by optical means. Here we report 14 new cases of PNET of bone (other than Askin's neoplasm) located primarily in the limbs, pelvic girdle and scapula. Clinically and radiologically they displayed Ewing's sarcoma-like features: mean age was 14.4 years, male/ female ratio being 3:11. Metastasis was present in 6 cases at diagnosis (5 with bone metastasis). Prognosis was poor; thirteen patients died; only one with a metatarsal located tumour is alive and free of disease. The mean survival rate was 25 months following diagnosis and treatment with radio- and multimodal chemotherapy. Histologically the 14 cases displayed Homer-Wright rosettes and pseudorosette-like structures, as well as a fibrillary background and lobular pattern. Immunohistochemistry revealed positivity in a number of neural markers when using paraffin-embedded material: NSE, B-2-microglobuline, HNK-1 (leu-7) and E-36 antibodies. At EM level the cell cytoplasms evidenced dense-core granules with neurosecretion, neurotubules and intermediate filaments like those seen in peripheral neuroepithelioma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750576
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  • 4
    Digitale Medien
    Digitale Medien
    Alveolar soft part sarcoma (1988)
    Springer
    Virchows Archiv 412 (1988), S. 499-513 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Alveolar soft part sarcoma ; Cytology ; Electron microscopy ; Immunohistochemistry ; DNA analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The type, differentiation and histogenesis of the tumor cells of alveolar soft part sarcoma (ASPS) have been analyzed in a series of ten cases by a light-microscopic, ultrastructural, immunohistochemical and cytologic investigation and quantitative DNA analysis. Four tumors deviated from ordinary ASPS: three were wholly or partly of the so-called pleomorphic variant of ASPS and a fourth tumor showed calcifications of the psammoma body type. The ultrastructural findings and immunohistochemical demonstration of desmin supported the hypothesis of a rhabdomyomatous differentiation and gave no support to epithelial (negative immunoreactions for cytokeratins, epithelial membrane antigen, HMFG-1 and -2, tissue polypeptide antigen (TPA)) or neuroectodermal (negative for S-100 protein, glial fibrillary acidic protein, neurofilaments) differentiation. The negative immunoreactions for vimentin and myoglobin and the positive reaction for neuron specific enolase (NSE) do not exclude a rhabdomyomatous differentiation since in rhabdomyosarcomas the undifferentiated rhabdomyoblasts generally contain vimentin and the differentiated tumor cells contain myoglobin and rhabdomyosarcoma has previously been reported as being positive for NSE. The production of external lamina material peripherally in the tumor cell nests and around vessels in the vascular septa was demonstrated both ultrastructurally and by immunohistochemistry using antibodies against collagen IV and laminin. The cytologic appearance in smears obtained by fine-needle aspiration from a case of the pleomorphic variant showed some resemblance to that of a carcinoma. The seven tumors with an ordinary cell appearance were found to show a diploid DNA-distribution at a quantitative analysis performed on paraffin sections, while the three tumors wholly or partly of the pleomorphic type showed an additional tetraploid peak.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00844286
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  • 5
    Digitale Medien
    Digitale Medien
    Ultrastructural and immunohistochemical findings in oral hairy leukoplakia (1988)
    Springer
    Virchows Archiv 412 (1988), S. 533-542 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Hairy leukoplakia ; Electron microscopy ; Epstein-Barr virus ; Candida albicans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Three cases of HL from the lateral border of the tongue of male homosexual AIDS patients were investigated by thin section electron microscopy. Keratinocytes contained condensed chromatin in their pyknotic nuclei and a few organelles in the oedematous cytoplasm. Chromatin was in close association to the nuclear membrane and showed a punched-out appearance. Particles typical of the herpes virus group were abundant in the upper two thirds of the epithelium in all three cases. Virus particles were seen frequently in the nuclei of the ballooned keratinocytes, but rarely in cells containing Candida albicans. Viral nucleocapsids were observed budding at the inner nuclear membrane, thereby acquiring the prospective viral envelope. Complete, enveloped virions were found in the endoplasmic reticulum and in the extracellular space. These virions were identified immunohistochemically as Epstein-Barr virus (EBV) using two monoclonal antibodies directed against EBV capsid and membrane antigen, respectively. Candida albicans was observed in the stratum corneum and in the upper layer of the stratum spinosum. Special cytoplasmic tubular structures arranged in parallel bundles were found in koilocytotic cells in addition to characteristic membrane structures composed of undulating convoluted membranes. Epithelial basement membranes were always intact.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00844289
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  • 6
    Digitale Medien
    Digitale Medien
    Ultrastructural features of acute monoblastic leukaemia cells: A multivariate morphometric analysis (1988)
    Springer
    Virchows Archiv 414 (1988), S. 21-27 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Monoblastic leukaemia ; Electron microscopy ; Morphometry ; Multivariate statistics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Morphometric studies were carried out on five ultrastructural measures of size or quantity of some of the intracellular organelles in monoblasts obtained from six patients diagnosed as having acute monoblastic leukaemia and also on monocytes from six normal controls. The morphometric measures were analysed using a one way multivariate analysis of variance (MANOVA) to see whether acute monoblastic leukaemic cells differed from those of normals. It was found that there was a highly significant decrease both in the surface to volume ratio of mitochondria and also in the surface to volume ratio of the nucleus. The possible physiological significance of these structural changes is stressed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00749734
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  • 7
    Digitale Medien
    Digitale Medien
    Osteosarcoma with a clear-cell component (1988)
    Springer
    Virchows Archiv 412 (1988), S. 273-279 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Osteosarcoma ; Clear cell ; Histopathology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The reports concerns the light microscopical and ultrastructural findings obtained in three conventional osteosarcomas with an unusually high admixture of clear cells, whose presence appeared to be responsible for the marked change in the histological pattern of these tumours. In the tumours with a prevailing fibroblastic component the clear cells were either irregularly scattered throughout the tumour in the form of small groups, or they formed large groups sharply demarcated against the fusicellular areas of the tumours. In two cases it was shown that their cytoplasm contained exaggerated glycogen deposits accompanied by the formation of glycogen-containing phagolysosomes and occasional empty vacuoles. In the third case the clear cells showed vacuolar degeneration with numerous single-membrane-bound, empty vacuoles. In contrast to the clear-cell chondrosarcoma we did not find S-100 protein in clear cells of our osteosarcomas. Such findings could be particularly significant in the differential diagnosis of bone tumours.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00737152
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  • 8
    Digitale Medien
    Digitale Medien
    Oncocytomas and null cell adenomas of the human pituitary: Morphometric and in vitro functional comparison (1988)
    Springer
    Virchows Archiv 413 (1988), S. 333-339 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Electron microscopy ; Morphometry ; Null cell adenoma ; Oncocytoma ; Pituitary adenoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In this study, light microscopic and ultrastructural morphometric features of oncocytomas and null cell adenomas were compared and the morphometric data were correlated with in vitro endocrine activity. All tumours were unassociated with clinical or biochemical evidence of hormone excess and were diagnosed as oncocytomas or null cell adenomas, using histology, immunohistochemistry and electron microscopy. In oncocytomas, when compared with null cell adenomas, light microscopic morphometry revealed that total cell areas were significantly larger and nuclear cytoplasmic ratios were smaller due to an increase in cytoplasmic areas. Ultrastructural morphometry disclosed an abundance of mitochondria in oncocytomas. Absolute volumes of cytoplasmic organelles per cell were not reduced in oncocytomas compared with those of null cell adenomas. These results indicate that accumulating mitochondria do not replace other cytoplasmic organelles, and furthermore that the functional potential of oncocytomas is not lost. In vitro study demonstrated the production of pituitary hormones, primarily gonadotropins in oncocytomas and null cell adenomas. It can be concluded that oncocytomas, which represent the final stage of oncocytic transformation, have a close relationship with null cell adenomas based on morphometric comparison as well as in vitro studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00783026
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  • 9
    Digitale Medien
    Digitale Medien
    Small cell neuroendocrine carcinoma of the urinary bladder (1988)
    Springer
    Virchows Archiv 413 (1988), S. 505-512 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Neuroendocrine differentiation ; Immunohistochemistry ; Electron microscopy ; Small cell undifferentiated bladder carcinoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Small cell carcinoma with the histological appearance of pulmonary small cell carcinoma is a rare tumour in the urinary bladder. In previous case reports the neuroendocrine nature of small cell bladder carcinoma has been accepted, but on review the evidence for true neuroendocrine differentiation appears unsatisfactory. In this study the histological, immunohistochemical and ultrastructural characteristics of three cases of small cell carcinoma of the urinary bladder are described. Ultrastructurally, the cytoplasm of all three tumours contained neurosecretory-type granules and each of the tumours demonstrated positive immunoreaction for two or more neuroendocrine markers, from a panel including neuron-specific enolase, chromogranin A, Leu-7, bombesin and synaptophysin. Although the combination of ultrastructural and immunohistochemical examination obviously offers the strongest evidence in establishing neuroendocrine differentiation, it is argued that immunohistochemistry alone may also yield important information in demonstrating a neuroendocrine nature, provided that at least neuron-specific enolase and synaptophysin are included as markers. The clinical relevance of identifying neuroendocrine differentiation in small cell bladder carcinoma is suggested by the favourable response to combination chemotherapy in two of our cases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750391
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  • 10
    Digitale Medien
    Digitale Medien
    Do folliculo-stellate adenomas of the pituitary gland exist or are they intrasellar meningiomas? (1988)
    Springer
    Acta neuropathologica 77 (1988), S. 219-223 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Meningioma ; Folliculo-stellate cell ; Pituitary neoplasm ; Electron microscopy ; Immunochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A tumor arising in the pituitary fossa and having some of the histological and ultrastructural features of a recently described tumor, purportedly originating from the folliculo-stellate cells of the anterior pituitary, is presented. The results of our ultrastructural and immunohistochemical studies, however, favored a meningeal origin and suggested that the neoplasm was most likely a secretory meningioma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687435
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  • 11
    Digitale Medien
    Digitale Medien
    Structural changes in the rat brain after carotid infusions of hyperosmolar solutions (1988)
    Springer
    Acta neuropathologica 77 (1988), S. 5-13 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Blood-brain barrier ; Hyperosmolar solutions ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Infusion of hypertonic solutions into the carotid artery is one method by which the blood-brain barrier (BBB) can be opened transiently in experimental animals. This technique has also been tried in clinical situations in which an enhanced uptake of intravenously injected chemotherapeutic drugs into the brain is desired. We have previously found that infusion of hypertonic mannitol or urea into the carotid artery of the rat, leading to a BBB opening, is associated with light microscopic signs of cellular damage in the brain parenchyma. An electron microscopic study has now been made to obtain more detailed information about the events taking place in the rat brain 1 to 72 h after an intracarotid infusion of hyperosmolar solution of mannitol. Toluidine blue-stained semithin epon sections were also available for high-resolution light microscopy of brain samples from urea-infused animals. Intravenously injected Evan's blue dye was used to confirm that BBB opening had occurred as a consequence of the carotid infusions. The infused hemispheres had numerous structural changes. The dominating light microscopic alteration was the presence of multifocal lesions in the gray or the white matter with closely packed microvacuoles causing status spongiosus. Ultrastructurally the microvacuoles corresponded to very pronounced watery swelling of astrocytic processes and to a minor degree to expansion of dendrites and axons. There was also a light or moderate perivascular astrocytic swelling. In the “spongy” lesions as well as occasionally in non-vacuolated parts of the cerebral cortex, there were collapsed electron-dense neurons with pronounced mitochondrial alterations such as severe swelling associated with rupture of christae. Rats with a survival period of 24 h or 72 h showed several disintegrating neurons and accumulation of macrophages. This study shows that carotid infusion of hypertonic mannitol in the rat may cause pronounced neuronal changes as well as multifocal astrocytic swelling. The severity of the nerve cell changes and the presence of macrophages indicate that some of the alterations are irreversible and thus, such a procedure may not be as safe as previously suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688236
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  • 12
    Digitale Medien
    Digitale Medien
    Nerve cell injury in the brain of stroke-prone spontaneously hypertensive rats (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 227-237 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Stroke-prone spontaneously hypertensive rats ; Blood-brain barrier ; Brain edema ; Nerve cell injury ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The brain lesions in stroke-prone spontaneously hypertensive rats (SHRSP) are characterized by multifocal microvascular and spongy-cystic parenchymal alterations particularly in the gray matter. An essential feature of the lesions is the presence of edema with massive extravasation of plasma constituents as evidenced by specific gravity measurements, Evans blue technique and immunohistochemistry. The nerve cell injury occurring in the brain lesions in SHRSP is further characterized by light and electron microscopy in the present study. Two types of neuronal changes were seen within the blood-brain barrier (BBB) leakage sites. A small number of neurons with dark condensed nucleus and cytoplasm were found most often at the periphery of recent lesions. The majority of injured neurons were pale and showed intracellular edema confined to the dendrites and perikarya sparing axons and synapses. Their nuclei were weli preserved with finely dispersed chromatin. The swollen and watery cell processes of neurons and astrocytes gave a spongy appearance to the neuropil. The intracellular edema seemed to result in cytolysis. The results suggest that primary anoxiaischemia is not the major pathogenetic mechanism behind the nerve cell injury in severely hypertensive SHRSP, rather it is the massive BBB leakage and consequent brain edema that causes cytolytic destruction of neurons. Secondary focal ischemia as a consequence of occlusion in microvessels may, however, contribute to the nerve cell destruction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687769
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  • 13
    Digitale Medien
    Digitale Medien
    The ultrastructural organization of the isthmic nucleus in Xenopus (1988)
    Springer
    Anatomy and embryology 177 (1988), S. 325-330 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Isthmic nucleus ; Electron microscopy ; Tectal ablation ; Xenopus ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The isthmic nucleus (IN) of the frog brain forms a linkage, relaying visual information from one tectum to the other. It receives afferent input from the tectum of the same side and projects bilaterally to both tecta. The ultrastructural features of the tecto-isthmic synaptic connections were studied in young postmetamorphic Xenopus frogs. Most synaptic profiles in the isthmic nucleus have spheroidal vesicles and an asymmetric zone of apposition. Frequently, synaptic glomeruli consisting of up to 8 terminal boutons surrounding a shaft dendrite were observed. The syanptic density in the rostral IN was slightly higher than in the middle or caudal portions. Partial deafferentation by transection of the tectoisthmic pathway or total deafferentation by removal of the tectum was followed by a widespread degeneration of terminals in the ipsilateral IN. In the former case, the density of synapses in the IN decreased initially by about 64%, and then increased by 30 days after operation to about 50% of the normal synaptic density. After tectal removal, all the terminal boutons in the isthmic neuropil degenerated by 3 days after operation. These studies, along with recent findings, indicate that most, if not all, of the afferent fibres to IN are of tectal origin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00315840
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  • 14
    Digitale Medien
    Digitale Medien
    Fine structural survey of Gudden's tegmental nuclei in the rat: cytology and axosomatic synapses (1988)
    Springer
    Anatomy and embryology 177 (1988), S. 485-493 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Ventral tegmental nucleus of Gudden ; Dorsal tegmental nucleus of Gudden ; Quantitative morphometric study ; Synaptic organization ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The fine structure of neuronal somata and axosomatic synapses in each subnucleus of Gudden's tegmental nuclei was studied by use of electron microscopy. The pars principalis of the ventral tegmental nucleus of Gudden (TVP) is composed of oblong or triangular, medium sized neurons (11.8x22.6 μm, 211.4 μm2) containing many mitochondria, lysosomes, Golgi apparatus, and rough endoplasmic reticulum composing Nissl bodies. The light oval nucleus with a prominent nucleolus is centrally situated, and indentations of its nuclear envelope are recognized in all neurons. The neuron in the pars ventralis of the dorsal tegmental nucleus of Gudden (TDV) is similar to that in the TVP, but its average size is significantly smaller (10.0x18.8 μm, 151.4 μm2), and its organelles are also less well developed. The pars dorsalis of the dorsal tegmental nucleus of Gudden (TDD) is composed of spindle shaped, small neurons (6.9x16.2 μm, 85.1 μm2) characterized by their irregular shaped nucleus with its invaginated envelope. These neurons have a thin rim of cytoplasm, poorly developed organelles and no Nissl bodies. The average number of axosomatic terminals in a sectional plane is 9.9 in the TVP, 9.6 in the TDV and 2.6 in the TDD, and the bouton covering ratio is 24.3% in the TVP, 26.5% in the TDV and 7.4% in the TDD. The respective percentages of round, flat and pleomorphic type axosomatic terminals were estimated, and the flat type terminals were found to be dominant in the TVP, the pleomorphic type terminals in the TDV, and the round type terminals in the TDD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305136
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  • 15
    Digitale Medien
    Digitale Medien
    Quantitative electron microscopic observations on the non-neuronal cells and lipid droplets in the posterior funiculus of the kitten after dorsal rhizotomy (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 95-105 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Electron microscopy ; Glial cells ; Perivascular cells ; Lipid droplets ; Wallerian degeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Kittens were subjected to lumbosacral dorsal rhizotomies at the age of 6–8 days postnatally. After postoperative survival times of 1–25 days the number of non-neuronal cells and lipid droplets in each cell type in the posterior funiculus at L1 were counted at the ultrastructural level. Intact control animals were analyzed in the same way. The number of astrocytes and oligodendrocytes decreased with increasing postoperative survival time in the degenerating zone. This was also the case in the white matter of control animals with increasing age of sacrifice. However, in the degenerating zone of operated animals the decrease was more extensive for oligodendrocytes starting at 5 days after surgery, and possibly also for astrocytes at 25 days postoperatively. The number of microglial cells in the degenerating zone was markedly increased 2–10 days after surgery compared to the controls. The number of non-pericytic perivascular cells seemed to be somewhat increased from 9 days after surgery, while the number of pericytes remained unchanged during the experimental period. Lipid droplets in the degenerating white matter were mainly located in microglial cells and astrocytes and only to a small extent in nonpericytic perivascular cells. These findings suggest that lipid material produced during anterograde fiber degeneration in the immature white matter is mainly metabolized in glial cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463643
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  • 16
    Digitale Medien
    Digitale Medien
    Ultrastructure of preimplantation rabbit embryos exposed to visible light and room temperature (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 229-241 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Room temperature ; Visible light ; Preimplantation embryos ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Early cleavage stage embryos (day 1 p.c.) and morulae (day 3 p.c.) of rabbits were exposed to visible (standard) lighting (1600 lx) and room (standard) temperature (23°C) during a 24 h in-vitro culture. Control embryos were cultured in darkness at 37°C. Development was assessed by light and electron microscopy as well as by the cytochemical demonstration of glycogen. In day 1 and day 3 embryos standard temperature induced swelling of the SER and Golgi complex vesicles. Major changes in day 1 embryos consisted of smallish microtubules-like crystalloids, and in day 3 embryos of unusually large SER vesicles. In both embryonic ages cleavage rate and development was more retarded by standard temperature than by standard lighting. Standard lighting, however, led to distinct signs of degeneration and cell death. The mode of cell damage seemed to be different in light exposed early cleavage stages and morulae: In day 1 embryos cytoplasmic degeneration was predominant while the majority of cells in day 3 embryos died by apoptosis. Despite clear indications of cell damage, cleavage rate was not notably impaired compared with non-exposed controls. Glycogen increased during development from cleavage stages to early blastocysts. The distribution was not changed either by exposure to standard temperature nor by standard lighting. The results demonstrate that day 1 embryos were clearly more susceptible to lighting whereas day 3 embryos were more affected by temperature. The mode of damage exerted by both the physical environmental factors was different. Reduction to standard temperature interfered mainly with the organization of the cytoskeleton and intracellular transport of organelles, while exposure to standard lighting led to cell degeneration and death.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318226
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  • 17
    Digitale Medien
    Digitale Medien
    Heterogeneities of the islets in the rabbit pancreas and the problem of “paracrine” regulation of islet cells (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 297-307 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Rabbits ; Islands of Langerhans ; Electron microscopy ; Immunohistochemistry ; Regulation of islands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In addition to “external” signals conveyed by the circulation or the nervous system, the pancreatic islets obviously are regulated also by “internal” (intra-islet) signals, e.g. by the islet hormones: insulin (B-), glucagon (A-), and somatostatin (D-) cells are able to affect the secretion of the heterologous cell types. It is, however, unclear whether this functional cooperation between islet cells occurs by an intercellular route (paracrinia sensu strictore), by intraislet “portal” vessels, or by the systemic circulation. These likely interactions are limited by islet anatomy. To identify the anatomical basis for the mutual functional relationships between the islet cells, islets of Langerhans in the rabbit pancreas were completely analyzed in immunostained serial semithin (0.5 μm) sections. The islets were found to be largely heterogenous. They were classified in three basic types: a) polycellular islets, composed of all established endocrine cells, and including two subtypes of islets, b) bicellular islets, containing only B- and A-cells or B- and D-cells, and c) monocellular islets, exclusively made up of B-cells. Concerning the modes of paracrine regulation of islet cells, the findings suggest primarely an endocrinous route of transport of the islet peptides to heterologous endocrine cells. The corresponding functional cooperation between islet cells probably is mediated rather by the systemic circulation than by intra-islet portal vessels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00698661
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  • 18
    Digitale Medien
    Digitale Medien
    Light and electron microscopic investigation of the rat placenta after cadmium administration during pregnancy (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 345-351 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Cadmium, Placenta (rat) ; Morphometry ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The morphology of the rat placenta was studied after exposure to cadmium chloride during pregnancy, using optimal fixation conditions. In contrast to previous observations, no differences were observed after cadmium administration in relative volume densities of trophoblastic tissue, maternal lacunae, fetal capillaries and connective tissue, nor in trophoblastic thickness or other morphometric features. At the ultrastructural level, the amount of glycogen in trophoblast layer II was elevated in cadmium exposed rats, but other electron microscopic features (amount and localization of lipid, degenerative vesicles, thickness and general appearance of the trophoblastic and endothelial layers and thickening or multiplication of the basal lamina) were not changed. Results obtained from the present experiments do not support the suggestion that cadmium is responsible for structural changes in the placentae of human smokers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00698665
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  • 19
    Digitale Medien
    Digitale Medien
    Quantitative assessment of taurine-like immunoreactivity in different cell types and processes in rat cerebellum: an electronmicroscopic study based on a postembedding immunogold labelling procedure (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 407-421 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Taurine ; Immunocytochemistry ; Quantification ; Electron microscopy ; Cerebellum ; Purkinje cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrathin sections of plastic-embedded rat cerebella were incubated with an antiserum against conjugated taurine and subsequently treated with a secondary antibody coupled to colloidal gold. The density of gold particles in various cellular profiles was calculated with the assistance of a computer. In the cerebellar cortex the highest density was found in the somata, dendrites, and dendritic spines of the Purkinje cells, supporting parallel light-microscopical observations in postembedding stained semithin sections from the same tissue blocks. The remaining profiles could be divided into three groups according to their immunolabelling intensity, in descending order: 1) somata and processes of granule and Golgi cells; 2) somata and processes of stellate, basket, and glial cells, and 3) mossy fiber terminals. In a representative experiment, the structures in the first and second groups showed gold particle densities in the range of 19–25%, and 4–11%, respectively, of that in the Purkinje cell somata (values corrected for background) whereas the particle density in the mossy fiber terminals was not significantly above background level. In the cerebellar nuclei, taurine-like immunoreactivity was concentrated in terminals that typically established symmetric or intermediate type contacts with weakly labelled dendrites and cell bodies. These terminals, which shared the ultrastructural features of Purkinje cell terminals, showed an average gold particle density that was about 60% higher than that of the Purkinje somata. For specificity control, ultrathin sections containing a series of different amino acid conjugates were incubated in the same drops of sera as the tissue sections. The highly selective labelling of the taurine conjugate indicated that the distribution of gold particles in the tissue was not confounded by crossreactivity with GABA, glutamate or other common amino acids but adequately reflected the distribution of fixed taurine. For additional control of specificity, the taurine antiserum was applied to the soluble fraction of a rat brain extract separated by thin layer chromatography. In this system the taurine antiserum stained a single spot that comigrated with free taurine. The present results suggest that all cell types and processes in the rat cerebellum (with the exception of the mossy fiber terminals) contain taurine. However, the concentration of taurine appears to vary considerably among the different cell types and may also differ between different parts of the same neuron.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306047
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  • 20
    Digitale Medien
    Digitale Medien
    Proliferation of rat intraspinal Schwann cells following tellurium intoxication (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 624-627 
    Details
    ISSN: 1432-0533
    Schlagwort(e): X-Irradiation ; Intraspinal Schwann cell ; Myelin ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A stable population of intraspinal Schwann cells, which developed follwing early postnatal irradiation of the spinal cord, was challenged by the addition of tellurium (Te) to the diet beginning at 30 days of age. Schwann cells incorporating [3H]thymidine were identified by 1 μm autoradiographs and by conventional electron microscopy of adjacent thin sections. Autoradiographs of areas with Schwann cell myclination showed extensive labelling of cells in the Te-fed animals. In contrast, control animals which were not fed Te showed little evidence of labelled Schwann cells. These data indicate that Schwann cells in the intraspinal environment show a proliferative response to the presence of Te in the rat's diet, as do Schwann cells in their normal extraspinal milieu.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689602
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  • 21
    Digitale Medien
    Digitale Medien
    Abnormal amianthoid collagen fibers in meningioma (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 638-639 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Meningioma ; Electron microscopy ; Collagen ; Amianthoid fibers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electron microscopic examination of a spinal meningioma demonstrated broad zones with large amianthoid collagen fibers in the tumor. Normal native collagen fibrils were found in small scattered clumps particularly around the blood vessels in the tumor. Such abnormal large collagen fibrils have not been seen previously in meningiomas. The significance of the amianthoid fibers is unknown. The only other unusual feature of the tumor was that it had many pale-staining cells by light microscopy and was classified as a clear cell variant of meningioma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689605
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  • 22
    Digitale Medien
    Digitale Medien
    Morphological study of peripheral nerve changes induced by chloroquine treatment (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 253-260 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Chloroquine ; Peripheral neuropathy ; Nerve biopsy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Nerve biopsies were performed in four patients with suspected chloroquine induced neuromyopathy. Three of the patients were treated with high doses of chloroquine for connective tissue disease, while one patient was taking this drug as malaria prophylaxis. Morphological studies demonstrated the presence of segmental demyelination and remyelination in all cases. Cytoplasmic inclusions were observed in Schwann cells, in perineurial and endothelial cells, and in some interstitial cells. They were never observed within axons. Occasional curvilinear profiles were seen in perineurial and Schwann cells. Perineurial calcifications were observed in two cases. The results of this morphological study suggest that chloroquine neuropathy is essentially due primary involvement of Schwann cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00690533
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  • 23
    Digitale Medien
    Digitale Medien
    Human immunodeficiency virus (HIV)-related chronic relapsing inflammatory demyelinating polyneuropathy with multifocal unusual onion bulbs in sural nerve biopsy (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 529-534 
    Details
    ISSN: 1432-0533
    Schlagwort(e): HIV-related relapsing polyneuropathy ; Intrathecal HIV antibodies ; Nerve biopsy ; Electron microscopy ; Schwann cell morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This is obviously the first report on a case with a spontaneous sensu strictu relapsing variant of human immunodeficiency virus (HIV)-related polyneuropathy. Its manifestation preceded LAS. Intrathecal HIV-antibodies developed between the most severe third and fourth episode. Analysis of sural nerve biopsy was consistent with a multifocally accentuated chronic inflammatory demyelination, characterized by unusual onion bulb-like Schwann cell formations with irregular voluminous layers, electron density, aggregation of filaments, multiple indented nuclei, and numerous enclosed collagen pockets. A direct or immune-mediated indirect specific influence on Schwann cell morphology by HIV might be discussed. Virus-like particles and ultrastructural markers of HIV were not detectable.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687143
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  • 24
    Digitale Medien
    Digitale Medien
    A novel intradural extramedullary spinal cord tumor in young dogs (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 402-410 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Spinal cord tumor ; Dog ; Electron microscopy ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We have studied an unusual, spontaneous, intradural extramedullary spinal cord tumor in 12 dogs. Animals presented with paraparesis and ataxia early in life (11/12 ranged from 6 to 38 months of age) suggesting that these tumors may be congenital. Various breeds of dogs were represented with four cases in German Shepherds and three in retrievers; there was no sex predisposition. Post-mortem examinations revealed a single intradural mass consistently located between T10 and L2, which produced extensive compression of the spinal cord. Metastasis was never observed and significant pathological changes in other organs were lacking. Microscopic examination revealed solid sheets of ovoid to fusiform cells interspersed with areas of acinar and tubular differentiation. Some areas were rarified and focal squamous metaplasia was observed. Ultrastructural features included the presence of a continuous basal lamina, junctional complexes, microvilli and occasional cilia at the apices of acinar complexes. Immunocytochemical studies did not support a neurectodermal origin. At least 13 case reports of this entity have been previously published and have been designated ependymomas, medulloepitheliomas and neuroepitheliomas. A recent case was diagnosed as a nephroblastoma and we feel that this is an interesting and provocative diagnosis. These tumors could result from remnants of renal primordium which becomes trapped between the dura and the developing spinal cord. However, firm evidence of such a histogenesis is not yet at hand.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687794
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  • 25
    Digitale Medien
    Digitale Medien
    Ultrastructural analysis of neurofibrillary tangles of Alzheimer's disease using computerized digital processing (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 519-522 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Alzheimer's disease ; Neurofibrillary tangle ; Paired helical filament (PHF) ; Electron microscopy ; Computerized digital processing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructure of neurofibrillary tangles of Zlzheimer's disease was analyzed by computerized digital processing of electron micrographs. Processing of the electron micrographs consists of four steps: digitizing the electron micrograph, Fourier transformation, noise filtering and inverse Fourier transformation and Laplacian operation. In the present study, we have confirmed that neurofibrillary tangles are composed of a pair of helical filaments (PHF), which appear characteristically as an unbranched rigid structure. The periodicity of PHF is 78nm on the diffractogram. The dimensions of PHF obtained by our analysis, although basically similar to those described earlier by other investigators using conventional techniques, more precisely defines its structural conformation. We have also demonstrated that the spatial relationship of two filaments appears symmetrical after two-way tilting of the specimen about the axis of rotation. Our observations emphasize the importance of digital image processing as an effective tool for structural analytical research in biology and medicine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687141
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  • 26
    Digitale Medien
    Digitale Medien
    Ultrastructural pathology of dermal axons and Schwann cells in lysosomal diseases (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 489-495 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Dermal nerves ; Electron microscopy ; Lysosomal diseases ; Terminal axons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Skin tissue specimens, obtained from 60 patients afflicted with a diverse range of lysosomal disorders revealed two groups of lesions within dermal axons, largely unmyelinated ones, particularly within axonal terminals: (1) non-specific mitochondria and dense bodies often enlarging the axonal terminal; and (2) disease-specific lysosomal residual bodies, the latter less frequent depending on the incidence and type of lysosomal disorders, i.e., largely only seen in GM2-gangliosidosis due to hexosaminidase A deficiency and mucolipidosis IV, while the spectrum of lysosomal residual bodies in Schwann cells appeared more variegated, especially due to the occurrence of vacuolar lysosomal residual bodies which were never seen within axons. The most frequent location of abnormal intraaxonal constituents in terminal axons indicates a functionally and morphologically impaired retrograde axonal transport but provides no further evidence as to whether the respective parent nerve cell body has also accumulated lysosomal residual bodies. When studying biopsied skin specimens for diagnosis, axonal terminals beneath the epidermis, about sweat glands, and among smooth muscle cells, ought to be incorporated into a comprehensive electron microscopic examination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686388
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  • 27
    Digitale Medien
    Digitale Medien
    The postsynaptic targets of substance P-immunoreactive terminals in the rat neostriatum with particular reference to identified spiny striatonigral neurons (1988)
    Springer
    Experimental brain research 70 (1988), S. 361-377 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Neostriatum ; Substance P ; Immunocytochemistry ; Golgi-impregnation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Substance P-immunoreactive boutons were examined in the electron microscope in sections of the rat neostriatum that contained retrogradely labelled striatonigral neurons and/or Golgi-impregnated medium-size densely spiny neurons. The postsynaptic targets of the immunoreactive boutons were characterized on the basis of ultrastructural features, their projection to the substantia nigra and/or their somato-dendritic morphology. Substance P-immunoreactive axonal boutons formed symmetrical synaptic specializations. Of a total of 233 randomly identified synaptic boutons 72.5% made contact with dendritic shafts, 15% with dendritic spines and 10.7% with perikarya. The ultrastructural characteristics of some of the postsynaptic neuronal perikarya were consistent with their identification as striatal interneurons. Similarly, the observation of some of the substance P-containing terminals in contact with spines, spine-bearing dendritic shafts and perikarya with the ultrastructural characteristics of medium-size densely spiny neurons suggested that one of the targets of substance P-positive terminals are striatal projection neurons. Direct evidence for this was obtained in sections from rats that had received injections of horseradish peroxidase conjugated with wheatgerm agglutinin in the substantia nigra. The perikarya of retrogradely labeled striatonigral neurons were found to receive symmetrical synaptic input from substance P-positive boutons. Ultrastructural analysis of Golgi-impregnated medium-size densely spiny neurons, some of which were also retrogradely labeled from the substantia nigra, demonstrated directly that this class of neuron was postsynaptic to the substance P-immunoreactive boutons. The combination of Golgi-impregnation with substance P-immunocytochemistry made it possible to study the pattern or topography of the substance P-positive input to medium size densely spiny neurons. The substance P-containing boutons made contact predominantly with perikarya and dendritic shafts. This pattern of input is markedly different from that of other identified inputs to medium-size densely spiny neurons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00248361
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  • 28
    Digitale Medien
    Digitale Medien
    The cholinergic innervation of the rat substantia nigra: a light and electron microscopic immunohistochemical study (1988)
    Springer
    Experimental brain research 72 (1988), S. 178-184 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Choline acetyltransferase ; Immunocytochemistry ; Substantia nigra ; Pedunculopontine tegmental nucleus ; Acetylcholine ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Putative cholinergic axons and synaptic endings were demonstrated in the substantia nigra (SN) of the rat by light and electron microscopy on the basis of the localization of choline acetyltransferase (ChAT) immunoreactivity. The distribution of ChAT immunoreactivity in the SN as demonstrated by light microscopy revealed a modest network of ChAT-immunoreactive beaded axons in the SNc, in comparison to a relatively sparse distribution in the SNr. These axonal profiles were most dense in the middle of the rostral-caudal extent of the SNc and appeared to be concentrated in the middle third of the medial-lateral extent. By electron microscopy, unmyelinated, small diameter (0.25 μm) ChAT-immuno-reactive axons were observed interspersed among numerous other non-immunoreactive axons in the SNc. ChAT-immunoreactive synaptic endings were observed in juxtaposition to small caliber (0.5 μm) non-immunoreactive dendrites, and contained numerous spheroidal synaptic vesicles and occasional mitochondria. Synaptic contact zones were characterized by an accumulation of synaptic vesicles along the presynaptic membrane, and a prominent postsynaptic densification producing an asymmetrical pre-/postsynaptic membrane profile typical of excitatory synapses. These findings provide direct evidence for a cholinergic innervation of the SN, and suggest that this input may have an excitatory effect on neuronal elements in the SNc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00248513
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  • 29
    Digitale Medien
    Digitale Medien
    Changes in microglial cell numbers in the spinal cord dorsal horn following brachial plexus transection in the adult rat (1988)
    Springer
    Experimental brain research 73 (1988), S. 61-68 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Microglia ; Dorsal horn ; Nerve lesion ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of peripheral nerve transection on the size of the microglial cell population in cytoarchitecturally distinct regions of the spinal cord dorsal horn of rats was evaluated at selected intervals 2 through 35 days after unilateral brachial plexotomy. The identification of cells was verified by electron microscopic examination of a representative random sample of cells included in the counts. Microglial cell numbers were increased in laminae I, II as well as the arbitrarily defined deeper laminae 3.5 days after surgery. Although microglial cell numbers in laminae I were within normal range 35 days after axotomy, those of the more ventrally located laminae remained significantly greater than control values for the duration of the experimental period. These findings demonstrate that: 1) microglial cell proliferation in the dorsal horn is an early event in the central changes that are attendant to peripheral nerve injury 2) the time course of the response varies in cytoarchitecturally different regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00279661
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  • 30
    Digitale Medien
    Digitale Medien
    Hypertension and nephrotoxic lesions in rats 1 year after prenatal exposure to gentamicin (1988)
    Springer
    Archives of toxicology 62 (1988), S. 274-284 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Gentamicin ; Postnatal development ; Blood pressure ; Embryotoxicity ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Using the aminoglycoside antibiotic gentamicin persistant functional and morphological changes were induced prenatally in the rat kidney. After 6 days of s.c. treatment (110 mg gentamicin/kg body wt) from day 10 to 15 of pregnancy complete resorption was noticed in 8 of the 14 treated animals. Fifty-three newborn were obtained from six dams. One year later only 26 rats (16 male, 10 female) were still alive. The systolic arterial pressure of the female offspring was significantly increased (139±15 mm Hg versus 112±9 mmHg) compared with controls. No statistically significant effect could be noticed in the male offspring (128±5 mm Hg versus 118±21 mm Hg). Corresponding results were obtained from analysis of urea plasma concentrations. Another cohort of pregnant rats received daily injections of gentamicin from day 15 to 20 of pregnancy (110 mg/kg body wt s.c.). In this group 59 newborn from a total of 109 died within the first 5 days after birth. Six litters were observed postnatally. One year after birth the following blood pressure values were determined: 122±4 mm Hg (male) and 132±17 mm Hg (female). Urea plasma concentrations were significantly higher in female, but not in male, offspring. Light and electron microscopic inspection revealed pathological changes in the kidneys of the female offspring only. The degree of maternal kidney damage — which shows considerable variations — was monitored during the treatment period. For this purpose the plasma gentamicin and urea concentrations were measured on 3 days of treatment in all of the pregnant animals. The postnatal data (mortality, blood pressure, and urea plasma concentrations) show a correlation to the degree of maternal kidney impairment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00332487
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  • 31
    Digitale Medien
    Digitale Medien
    Adult-onset rod disease with abundant intranuclear rods (1988)
    Springer
    Journal of neurology 235 (1988), S. 343-347 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Adult-onset rod disease ; Nemaline myopathy ; α-Actinin ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The third case of adult-onset rod disease (nemaline myopathy) with abundant myofibrillar as well as intranuclear rods is described. The 61-year-old woman suffered from progressive weakness of proximal extremities and of the neck, mimicking polymyositis. Muscle biopsy revealed a striking myopathic pattern, with intranuclear rods occurring in 31% of the fibres. On light and electron microscopy and by immunohistochemical study, the rods differed from myofibrillar rods. The absence of α-actinin in intranuclear rods suggests an enhanced readiness of actin filaments to bind to diverse proteins, instead of overproduction of α-actinin as the pathogenetic basis of the rod formation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00314229
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  • 32
    Digitale Medien
    Digitale Medien
    Immunocytochemical localization of two key enzymes of the 2-hydroxyglutarate pathway of glutamate fermentation in Acidaminococcus fermentans (1988)
    Springer
    Archives of microbiology 150 (1988), S. 504-508 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Acidaminococcus fermentans ; Glutamate fermentation ; Electron microscopy ; Immunocytochemistry ; Post-embedding labelling ; Antibody-gold complexes ; Protein A-gold complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have investigated the in situ location of glutaconyl-CoA decarboxylase and 2-htdroxyglutaryl-CoA dehydratase in Acidaminococcus fermentans using the antibody-gold and protein A-gold techniques carried out as a post-embedding immunoelectron microscopic procedure. Polyclonal antisera were raised in rabbits against homogeneous fractions of the enzymes. Anaerobically grown cells of A. fermentans of the late exponential growth phase were fixed with 0.2% glutaraldehyde and 0.3% formaldehyde (final concentrations) in the growth medium. Dehydration of the cells was achieved with methanol. The cells were embedded in the low temperature embedding resin Lowicryl K4M. The markers indicative for antigenic sites of the two enzymes unequivocally demonstrate that the sodium pump glutaconyl-CoA decarboxylase is located at the cell periphery being a membrane-bound enzyme as expected whereas 2-hydroxyglutaryl-CoA dehydratase is a soluble cytoplasmic enzyme.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00422295
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  • 33
    Digitale Medien
    Digitale Medien
    The production and utilization of intermediary elemental sulfur during the oxidation of reduced sulfur compounds by Thiobacillus ferrooxidans (1988)
    Springer
    Archives of microbiology 150 (1988), S. 574-579 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Thiobacillus ferrooxidans ; Sulfur production ; Sulfur oxidation ; Inhibitors ; Uncouplers ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The intermediary production of elemental sulfur during the microbial oxidation of reduced sulfur compounds has frequently been reported. Thiobacillus ferrooxidans, an acidophilic chemolithoautotroph, was found to produce an insoluble sulfur compound, primarily elemental sulfur, during the oxidation of thiosulfate, trithionate, tetrathionate and sulfide. This was confirmed by light and electron microscopy. Sulfur was produced from sulfide by an oxidative step, while the production from tetrathionate was initiated by a hydrolytic step, probably followed by a series of chemical reactions. The oxidation of intermediary sulfur was severely inhibited by sulfhydryl-binding reagents such as N-ethylmaleimide, by the addition of uncouplers or after freezing and thawing of the cells, which probably damaged the cell membrane. The mechanisms behind these inhibitions have not yet been clarified. Finally, it was observed that elemental sulfur oxidation by whole cells depended on the medium composition. The absence of sulfate or selenate reduced the sulfur oxidation rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00408252
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  • 34
    Digitale Medien
    Digitale Medien
    Structure of the mitochondrial genome of Beta vulgaris L. (1988)
    Springer
    Theoretical and applied genetics 76 (1988), S. 753-759 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Plant mitochondrial genome ; Minicircle DNA ; Electron microscopy ; Beta vulgaris L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The structure of mitochondrial DNA (mt-DNA) from sugarbeet (Beta vulgaris L.) has been studied by biochemical methods and electron microscopy. It was found to be complex multipartite consisting of two main classes of molecules: high molecules weight (HMW) mtDNA and low molecular weight (LMW) mtDNA. The HMW mtDNA consists of rosette-like structures and globules resembling chromomeres (150–200nm). A typical rosette has a protein core and radially stemming closed DNA loops (from 0.6-1.5 μm). The number of loops in a rosette varies from 16–30. The bulk of HMW mtDNAs are represented by interconnected rosettes (total contour length about 130–160 μm, 403–496 kbp). Such large circular DNAs may be evidence of the master chromosome arrangement of the sugarbeet genome. Globules and rosettes are interconnected by thick and thin DNA fibrils, along which nucleosome- and nucleomere-like structures are distributed. The LWM mtDNA is composed of two groups of supercoiled circular molecules, 0,2–1.5 μm and 0.02–0.05 μm in size. Electrophoretic analysis demonstrated that LWM mtDNA is represented by minicircle plasmid-like DNA molecules of 1.3, 1.4 and 1.6 kbp.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00303522
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  • 35
    Digitale Medien
    Digitale Medien
    Distribution of mitochondrial plasmid-like DNA in cultivated rice (Oryza sativa L.) and its relationship with varietal groups (1988)
    Springer
    Theoretical and applied genetics 76 (1988), S. 809-814 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Electron microscopy ; Genetic variation ; Mitochondrial DNA ; Oryza sativa L. ; Plasmid-like DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mitochondrial (mt) plasmid-like DNA was found in most of more than 100 rice cultivars (Oryza sativa L.) by the use of 0.7% agarose gel electrophoresis (AGE). The DNA varied in molecular weight and number. By electron microscopy, small circular DNAs of different sizes could be detected in addition to the DNAs of high molecular weight, even in cultivars in which mt plasmid-like DNA was not detected by AGE. The detection of the mt plasmid-like DNAs by AGE did not depend on their presence or absence, but on their high stoichiometry. The relationship between cytoplasms with mt plasmid-like DNAs and varietal (for example, Indica rice) groups was close. The geographical distribution of cytoplasms is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00273665
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  • 36
    Digitale Medien
    Digitale Medien
    Localization of 28 kDa calbindin in human odontoblasts (1988)
    Springer
    Cell & tissue research 254 (1988), S. 341-346 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Odontoblast ; Calbindin ; Immunohistochemistry ; Electron microscopy ; Teeth ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The presence of 28 kDa calbindin in human odontoblasts was studied by use of specific antibodies raised against chick duodenal 28 kDa calbindin, in immunofluorescence, immuno-peroxidase, and electron-microscopic labelling experiments. The calbindin-like protein was detected mainly in the cytoplasm of odontoblast cell bodies, in their processes and occasionally in their nuclei. Correspondingly, at the ultrastructural level, immunoreactive material was associated with the cytosol, microfilaments and cilia. These findings suggest that human odontoblasts express a 28 kDa vitamin D-dependent calcium-binding protein, unlike those of rats and mice in which ameloblasts are the only cells immunoreactive for the protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00225806
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  • 37
    Digitale Medien
    Digitale Medien
    Development of follicular dendritic cells in lymph nodes of B-cell-depleted mice (1988)
    Springer
    Cell & tissue research 254 (1988), S. 449-454 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Follicular dendritic cells ; Lymph nodes ; Electron microscopy ; Nude mice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary We have studied follicular dendritic cells (FDC) in lymph nodes of normal and thymus dysgeneic nude mice depleted of B-cells by chronic treatment with anti-IgM antibodies. We found that B cell depletion was accompanied by the absence of mature FDC as defined morphologically at the ultrastructural level. Only precursor FDC (p-FDC) could be demonstrated. Upon release of B-cell suppression, the repopulation of lymph nodes with B-cells was associated with the reappearance of fully differentiated FDC in primary follicles of nude mice and in secondary follicles of T-cell competent mice. We conclude that mature B-cells and/or B-cell products are required for the development of mature follicular dendritic cells in the mouse lymph node.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00225818
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  • 38
    Digitale Medien
    Digitale Medien
    Orthogonal arrays of particles in non-pigmented cells of rat ciliary epithelium: Relation to distribution of filipin- and digitonin-induced alterations of the basolateral membrane (1988)
    Springer
    Cell & tissue research 252 (1988), S. 165-173 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Ciliary epithelium ; Orthogonal arrays of particles ; Filipin ; Freeze-fracture ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary It has been suggested that orthogonal arrays of particles may increase the rigidity of plasma membrane, as does cholesterol. Therefore, using freeze-fractured non- pigmented ciliary epithelium, the distribution of such arrays was compared to the distribution of membrane deformations induced by the sterol-probes filipin and digitonin in different domains of the basolateral plasma membrane. The distribution of orthogonal arrays of particles was homogeneous between different regions of the basolateral membrane of the non-pigmented ciliary epithelium, while the number of filipin-induced alterations was nearly 4 times higher in the membrane domains not in contact with the basal lamina than in domains in contact with it. Contrary to the homogeneous distribution of arrays, digitonin-induced deformations also differed markedly in these two basolateral membrane domains. Considering that a marked positive response to sterol probes implies a high sterol content, we conclude that orthogonal arrays of particles can occur in plasma membrane regions well-provided with cholesterol and not in direct contact with the basal lamina. Other possible roles of these arrays are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213838
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  • 39
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of immunolabeled substance P and methionine-enkephalin-octapeptide in the surface layer of the dorsal horn of rat spinal cord (1988)
    Springer
    Cell & tissue research 253 (1988), S. 55-60 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Substance P ; Enkephalin ; Spinal dorsal horn ; Immunocytochemistry ; Electron microscopy ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A preembedding dual immunolabeling technique and electron microscopy were utilized to demonstrate the localization of immunoreactive substance P and methionine-enkephalin-octapeptide (Enk-8) in ultrathin sections of the surface layer (laminae I and II) of rat spinal dorsal horn. The immunoreaction of Enk-8 was visualized as goldtoned silver particles and that of substance P as diaminobenzidine reaction products. Axonal terminals with immunoreactive substance P, and also unlabeled axonal terminals, formed synaptic junctions with the perikarya and dendritic processes of Enk-8-containing neurons. Dendritic profiles immunolabeled for substance P were synaptically linked with unlabeled axons but not with Enk-8-positive ones. Furthermore, it was found that Enk-8 axons and substance P axons terminated synaptically in juxtaposition to one another on the same immunonegative dendrites. Among the Enk-8-containing neurons axonal profiles also appeared to be synaptically associated with immunoreactive Enk-8 dendritic processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221739
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  • 40
    Digitale Medien
    Digitale Medien
    Light- and electron-microscopic immunocytochemistry of peptidergic neurons innervating thoracico-abdominal neurohaemal areas in the blowfly (1988)
    Springer
    Cell & tissue research 253 (1988), S. 583-595 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Bioactive peptides ; Coexistence of peptides ; Immunocytochemistry ; Electron microscopy ; Insect nervous system ; Calliphora erythrocephala, C. vomitoria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ventral thoracic neurosecretory cells (VTNCs) of the blowflies, Calliphora erythrocephala and C. vomitoria, innervating thoracic neuropil and the dorsal neural sheath of the thoracico-abdominal ganglion have been shown to be immunoreactive to a variety of mammalian peptide antisera. In the neural sheath the VTNC terminals form an extensive neurohaemal network that is especially dense over the abdominal ganglia. The same areas are invaded by separate, ut overlapping serotonin-immunoreactive (5-HT-IR) projections derived from neuronal cell bodies in the suboesophageal ganglion. Immunocytochemical studies with different antisera, applied to adjacent sections at the lightmicroscopic level, combined with extensive cross-absorption tests, suggest that the perikarya of the VTNCs contain co-localized peptides related to gastrin/cholecystokinin (CCK), bovine pancreatic polypeptide (PP), Met- and Leuenkephalin and Met-enk-Arg6-Phe7 (Met-enk-RF). Electron-microscopic immunogold-labeling shows that some of the terminals in the dorsal sheath react with several of the individual peptide antisera, whilst others with similar cytology are non-immunoreactive. In the same region, separate terminals with different cytological characteristics contain 5-HT-IR. Both 5-HT-IR and peptidergic terminals are localized outside the cellular perineurium beneath the acellular permeable sheath adjacent to the haemocoel. Hence, we propose that various bioactive substances may be released from thoracic neurosecretory neurons into the circulating haemolymph to act on peripheral targets. The same neurons may also interact by synaptic or modulatory action in the CNS in different neuropil regions of the thoracic ganglion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219749
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  • 41
    Digitale Medien
    Digitale Medien
    The efferent innervation of the genital chamber by an identified serotonergic neuron in the female cricket Acheta domestica (1988)
    Springer
    Cell & tissue research 252 (1988), S. 449-457 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Serotonin (5-HT) ; Genital chamber ; Immuno-cytochemistry ; Electron microscopy ; Cricket, Acheta domestica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The serotonergic innervation of the genital chamber of the female cricket, Acheta domestica, has been investigated applying anti-serotonin (5-HT) immunocyto-chemistry at both light- and electron-microscopic levels as well as using conventional electron microscopy. Whole mount and pre-embedding chopper techniques of immuno-cytochemistry reveal a dense 5-HT-immunoreactive network of varicose fibers in the musculature of the genital chamber. All of these immunoreactive fibers originate from the efferent serotonergic neuron projecting through the nerve 8v to the genital chamber (Hustert and Topel 1986; Elekes et al. 1987). At the electron-microscopic level, 5-HT-immunoreactive nerve terminals, which contain small (50–60 nm) and large (∼ 100 nm) agranular vesicles as well as granular vesicles (∼100nm), contact the muscle fibers or the sarcoplasmic processes without establishing specialized neuromuscular connections. In addition to the 5-HT-immunoreactive axons, two types of immunonegative axons can also be found in the musculature. By use of conventional electron microscopy, three ultrastructurally distinct types of axon processes can be observed, one of which resembles 5-HT-immunoreactive axons. While the majority of the varicosities do not synapse on the muscle fibers, terminals containing small (50–60 nm) agranular vesicles occasionally form specialized neuromuscular contacts. It is suggested that the 5-HTergic innervation plays a non-synaptic modulatory role in the regulation circular musculature in the genital chamber of the cricket, while the musculature as a whole may be influenced by both synaptic and modulatory mechanisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00214388
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  • 42
    Digitale Medien
    Digitale Medien
    Atrial-specific granules in the hearts of normal and water-deprived rats (1988)
    Springer
    Cell & tissue research 253 (1988), S. 547-552 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Atrial-specific granule ; Atrial natriuretic polypeptide ; Water deprivation ; Immunohistochemistry ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology of atrial-specific granules, which contain atrial natriuretic polypeptide (ANP), was studied in the cardiac tissue of untreated controls and water-deprived rats by means of conventional and immunoelectron microscopy. Immature secretory vesicles or granules appeared to become buded off from the Golgi cisternae and then fused to form specific A-granules. An electron-dense plate with a fuzzy coat was frequently found on the limiting membrane at the end of such fusion. Pale specific B-granules, which were less electron-dense, larger, and more granular than A-granules, were found in small numbers in the left atrial cardiocytes, but rarely in the right ones. Very pale granules with a less granular matrix, considered to be B-type granules which had lost their electron-density, and which had less immunoreactivity for ANP, were numerous in the cardiac tissue after water deprivation. This morphological change, which is interpreted as an indication of granule degradation, was in agreement with the noted increase of natriuretic activity in the atrial tissue of water-deprived specimens.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219745
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  • 43
    Digitale Medien
    Digitale Medien
    Epidermal growth factor (EGF)-induced morphological changes in the basement membrane of chick embryonic skin (1988)
    Springer
    Cell & tissue research 254 (1988), S. 481-485 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Embryonic skin ; Epidermal growth factor ; Basement membrane ; Electron microscopy ; Chick
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effect of epidermal growth factor (EGF) on the basement membrane structure of chick embryonic skin cultured in a chemically defined medium (BGJb) containing 20 mM hydrocortisone, and EGF at 10, 50, or 100 ng/ml supplemented with 5% delipidized fetal calf serum, was examined by electron microscopy. During development of the epidermis in vitro, EGF (100 ng/ml) caused striking changes to occur in the basement membrane structure and in the keratinization process. The basement membrane frequently became discontinuous with many gaps apparent in section, and occasionally became folded following detachment from the basal surface of the epidermis and protruded into the underlying dermis. In the basal and intermediate cells of EGF-treated epidermis, tonofilament bundles were decreased in number, while desmosomes and hemidesmosomes revealed no significant changes in morphology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00226497
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  • 44
    Digitale Medien
    Digitale Medien
    Unifying principles in intermediate filament (IF) structure and assembly (1988)
    Springer
    Protoplasma 145 (1988), S. 73-81 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Intermediate filament structure ; Intermediate filament assembly ; Desmin ; Keratins ; Neurofilaments ; Nuclear lamins ; Cytoskeleton ; Electron microscopy ; Polymerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01349341
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  • 45
    Digitale Medien
    Digitale Medien
    Evaluation of 111In labelled white blood cells by in vitro functional tests and electron microscopy (1988)
    Springer
    European journal of nuclear medicine 14 (1988), S. 159-164 
    Details
    ISSN: 1619-7089
    Schlagwort(e): 111In-white blood cells ; Chemotaxis ; Phagocytosis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We have studied the influence of granulocyte labelling with commercially available 111In-oxine, tropolone (trop) or home made 111In-Mercapto pyridine (Merc) prepared by the method of Thakur (1985) on the cell structure by electron microscopy and on the cell function by enzymatic tests, random migration, chemotaxis, phagocytosis and bactericidal activity. The granulocytes were labelled with 400 μCi 111In-oxine in saline or 111In-trop or Merc in plasma. The effect of the chelating agents with and without addition of the tracer was studied (n=4) with varying concentrations: 5–10 μg/ml oxine, 10–160 μg/ml trop and 1–4 μg/ml Merc. Chemotaxis and random migration were not affected by 111In-trop and clearly supressed by 111In-oxine and Merc; the other tests were normal. The cell structure was disturbed by Merc. The labelling efficiency was excellent with oxine (90%), acceptable with trop (30%–80%) and poor with Merc (10%–25%). Without 111In, chemotaxis and random migration were normal up to a concentration of 80 μg/ml trop, 8.5 μg/ml oxine and 1 μg/ml Merc. With addition of 111In, chemotaxis and random migration were unaffected up to 80 gmg/ml by trop and markedly supressed by Merc and oxine. It is concluded that labelling with 111In-trop assures intact cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00293542
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  • 46
    Digitale Medien
    Digitale Medien
    The barrier-like role of activated connective tissue against the spread of supraglottic laryngeal carcinoma (1988)
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 151-154 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Supraglottic carcinoma ; Light microscopy ; Electron microscopy ; Activated connective tissue barrier
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Light microscopic investigations of whole organ serial sections of 15 laryngectomy specimens with supraglottic carcinomas and comparative electron microscopic studies of the upper and lower poles of the tumors were carried out. The ultrastructure of different poles of the same supraglottic tumors was investigated and showed a more progressive fibrillogenesis with an activation of the connective tissue elements of the border on the lower pole of the malignancy. A significant role is attributed to the barrierforming feature of activated connective tissue with respect to the inhibition of the extension of tumor into the glottic region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464017
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  • 47
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of Ca2+-binding sites in the spiral limbus, the stria vascularis and Reissner's membrane of the guinea pig (1988)
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 279-283 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Calcium ; Reissner's membrane ; Stria vascularis ; Limbus ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Cations were precipitated with potassium antimonate in the cochlea of the guinea pig and electron microscopy was used to analyze the distribution of the formed reaction products. Differences in precipitate density between neighboring cells in Reissner's membrane, in the stria vascularis and in the limbus are described. Electron spectroscopic imaging was performed to obtain information about the spatial distribution of the precipitates and their elemental composition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464630
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  • 48
    Digitale Medien
    Digitale Medien
    Rapid quantification of 11 prostanoids by combined capillary column gas chromatography and negative ion chemical ionization mass spectrometry: Application to prostanoids released from normal human embryonic lung fibroblasts WI38 in a culture medium (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 25-32 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rapid and simultaneous quantification of 11 prostanoids has been carried out with a short-capillary gas chromatograph and negative ion chemical ionization (ammonia) mass spectrometer.The methoxime-trimethylsilyl ether-pentafluorobenzyl esters (MO-TMS-PFB) of nine prostanoids, PGA1, PGA2, PGB1, PGB2, PGD2, PGE1, PGE2, 6-oxo-PGF1α and TXB2 and the TMS-PFB of two prostanoids, PGF1α and PGF2α, were separated in less than 5.5 min on a bonded OV-1 capillary column 0.25 mm i.d. × 6 m (0.15 μm thickness) using hydrogen as a carrier gas. PGD2, PGE2, PGF2α, 6-oxo-PGF1α and TXB2 were quantified up to 2.5 fmol injected (0.1 pmol derivatized) and both PGA2 and PGB2 up to 25 fmol injected (1 pmol derivatized).In order to maintain the stability of the prostanoids containing a carbonyl group, such as TXB2 during the purification and derivatization steps of biological materials, methyl acetate was used in place of methyl formate as an eluant for Sep-Pak C18 purification.Normal human embryonic lung fibroblasts W138 (5.63 × 105 cells in a log phase) produced: PGA2 15.28, PGB2 13.48, PGD2 7.95, PGE1 2.62, PGE2 177.76, PGF2α 25.14, 6-oxo-PGF1α 27.33 and TXB2 61.00 pmol in 10 ml of Eagle minimal essential medium.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150105
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  • 49
    Digitale Medien
    Digitale Medien
    Measurement of urinary lactic, 3-hydroxybutyric, pyruvic and acetoacetic acids in a single analysis using selected ion monitoring and stable isotope labelling techniques (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 57-62 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Sodium borodeuteride treatment of urine expected to have large concentrations of pyruvic and acetoacetic acids produces lactic and 3-hydroxybutyric acids labelled with deuterium. Mass fragmentographic techniques applied to the trimethylsilyated extract of the urine spiked with more extensively labelled analogues as internal standards permit the reliable determination of lactic, pyruvic, 3-hydroxybutyric and acetoacetic acids in a single analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150108
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  • 50
    Digitale Medien
    Digitale Medien
    Characterization of trichothecenes by ammonia chemical ionization and tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 79-87 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ammonia and deuterated ammonia chemical ionization (CI) mass spectra and collisionally activated dissociation (CAD) mass spectra of ammonium adduct ions are presented for ten trichothecenes. The samples were introduced by direct exposure probe. Effects of ion source temperature and pressure on the ammonia CI gas plasma and the formation of the ammonium adduct ion were studied. The CI conditions were optimized to produce a maximal yield for the ammonium adduct ion of trichothecenes, i.e. the parent ion for tandem mass spectral analysis. Besides source temperature and pressure, proton affinity and the stability of the ammonium adduct ion affect the relative abundance ratio of [M + H]+:[M + NH4]+ in ammonia CI and CAD mass spectra. The ratio [M + H]+:[M + NH4]+, and hence the stability of the ammonium adduct ion, are largely determined by the functional groups (hydroxy, carbonyl, acetoxy, and isovaleroyloxy) and their location in the trichothecene nucleus. The most abundant fragment ions in the ammonia CI spectra and the most abundant daughter ions in the CAD spectra of the ammonium adduct ions are formed by the losses of ammonia and functional groups as neutrals in various combinations.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150205
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  • 51
    Digitale Medien
    Digitale Medien
    The application of gas chromatographic/mass spectrometric techniques to spin trapping. Conversion of α-phenyl N-tert-butyl nitrone (PBN) spin adducts to stable trimethylsilylated derivatives (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 111-116 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of an aminoxyl and the corresponding hydroxylamine with silylating agents is studied in detail. The gas chromatographic/mass spectrometric analysis of the products is consistent with the production of an unsaturated product when an alkyl group with exchangeable hydrogens is attached to the nitrone group. The structure of this compound is confirmed by deuteration. It is concluded that aminoxyls themselves do not derivatize wth silylating agents.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150209
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  • 52
    Digitale Medien
    Digitale Medien
    Gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry of methyl ester/methoxime/trimethylsilyl ether derivatives of prostaglandins (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 129-138 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron impact mass spectra of methyl ester/trimethylsilyl ether derivatives of prostaglandin F2α and methyl ester/methoxime/trimethylsilyl ether derivatives of prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1α and 2,3-dinor-6-oxo-prostaglandin F1α are presented. Most of the prostaglandins studied have additionally been 2H-labelled at different sites in order to assign the corresponding fragment ions. Collisionally activated decomposition mass spectra of the most intense parent ions in the high-mass region were taken. High-intensity, prostaglandin-characteristic daughter fragments will allow a reliable quantification of prostaglandins in biological fluids and a reduction of sample clean-up.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150303
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  • 53
    Digitale Medien
    Digitale Medien
    A gas chromatographic/mass spectrometric assay for catechol estrogens in microsomal incubations: Comparison with a radiometric assay (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 157-161 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A gas chromatographic/mass spectrometric assay for quantifying two catechol estrogens, 2-hydroxyestradiol and 4-hydroxyestradiol, in microsomal preparations is described. The assay employs deuterium-labeled analogs of the catechol estrogens as internal standards and permits quantification of catechol estrogens, in microsomal incubations, at low (1-2) μM concentrations. The compounds are analyzed as their trimethylsilyl derivatives following separation by capillary gas chromatography.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150307
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  • 54
    Digitale Medien
    Digitale Medien
    Electron capture negative ion chemical ionization analysis of arachidonic acid (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 175-178 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A highly sensitive (subpicomole level) and structural specific method for the analysis of arachidonic acid esterified to complex glycerophospholipids has been developed using combined capillary gas chromatography and mass spectrometry. The methodology is based upon the formation of the pentafluorobenzyl ester of arachidonic acid, which is efficiently ionized using electron capture negative ion chemical ionization conditions to yield an abundant carboxylate anion at m/z 301. Quantification is carried out following hydrolysis of the complex glycerophospholipid in the presence of a known amount of (2H8) araachidonic acid. The use of this method is illustrated by the quantification of arachidonic acid within the glycerophospholipid classes isolated from resident peritoneal macrophage cells isolated from HS mice.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150309
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  • 55
    Digitale Medien
    Digitale Medien
    Mass spectral investigations on trichothecene mycotoxins. V. Direct analysis of satratoxins by tandem mass spectrometric techniques (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 185-191 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Under chemical ionization conditions, satratoxins preferentially produce negatively charged molecular ions (M-·) over the positively charged protonated molecules. Collisionally activated dissociation of the M-· ions resulted in daughter ions and neutral losses which were characteristic of the macrocyclic ester bridges. Direct tandem mass spectrometric methods of analyses wee developed and applied for the detection and quantification of satratoxins in Stachybotrys atra fermentation broths. Minimum detectable levels for satratoxin standards were 5 pg. A synthetically modified macrocyclic trichothecene, 8-ketoverrucarin A, was used as an internal standard for the quantification of satratoxins in fermentation samples.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150402
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  • 56
    Digitale Medien
    Digitale Medien
    Thermospray liquid chromatography tandem mass spectrometry: Application to the elucidation of zolpidem metabolismThis work was presented in part at the 4th Symposium on Liquid Chromatography/Mass Spectrometry and Mass Spectrometry/Mass Spectrometry, Montreux (Switzerland), October 22-24, 1986. (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 223-228 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper discusses the possible advantages of thermospray liquid chromatography/tandem mass spectrometry LC/MS/MS for metabolic mapping. The technique was applied to the study of the metabolism of zolpidem, a new hypnotic with an imidazo-pyridine moiety. When compared to other chromatographic/mass spectrometric-based techniques, reversed phase high-performance liquid chromatography coupled with thermospray LC/MS/MS appears to be the fastest method available today for elucidation of unknown metabolic structures, since it allows identification by direct injection of concentrated urine. However, it was noted during the thermospray process that loss of formaldehyde from a hydroxymethyl amide metabolite occurred. This degradation was not observed when this metabolite was analysed by gas chromatography/mass spectrometry following trimethylsilylation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150406
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  • 57
    Digitale Medien
    Digitale Medien
    Fast atom bombardment mass spectrometry of high-molecular-weight fraction of porphyrin-based photodynamic therapy drugs (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 257-263 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photodynamic therapy (PDT) involves the treatment of tumor tissue with a photosensitizer and light to effect the delineation and/or eradication of the tumor. PDT is a two step process: (1) incorporation of photosensitizer into the cell where it must be retained by tumors in vivo; and (2) illumination of the tumor cell with light to effect cell death. Hematoporphyrin derivative (HPD) is a complex mixture of porphyrins currently used for PDT in the clinical setting. Hematoporphyrin-based oligomers of up to five subunits were determined using fast atom bombardment mass spectrometry of the high-molecular-weight fraction of the drug. Reduction of this fraction with LiAlH4 permitted determination of the covalent bond linking the monomers in these oligoporphyrins. Application of these analytical procedures to the determination of the composition of different preparations of HPD will be described.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150505
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  • 58
    Digitale Medien
    Digitale Medien
    (18O)quinolinic acid: Its esterification without back exchange for use as internal standard in the quantification of brain and CSF quinolinic acid (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 291-293 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the process of developing a high-sensitivity negative chemical ionization gas chromatographic/mass spectrometric assay for brain and cerebrospinal fluid (CSF) levels of quinolinic acid (QUIN, 2,3-pyridine dicarboxylic acid), (18O4)QUIN was prepared. Its properties as an internal standard were compared with those of the structural isomer 2,4-pyridine decarboxylic acid (2,4-PDC) previously used by others. All oxygen atoms in QUIN were labeled by heating in 3N HCl/(18O)water for 48 h at 80°C. Back-exchange of (18O4)QUIN was prevented during derivatization to an electron-capturing dihexafluoropropanol ester by using trifluoroacetylimidazole as catalyst instead of perfluroacyl anhydrides. When mixtures of QUIN and (18O4)QUIN and/or 2,4-PDC were followed through a procedure to isolate and quantify brain and CSF QUIN, the variability in the ratio of QUIN:2,4-PDC was greater than for QUIN:(18O)QUIN. We conclude that (18O)QUIN is the preferred internal standard in gas chromatographic/mass spectrometric quantification of brain and CSF QUIN, and that (18O)-labeled carboxylic acids may be esterified effectively without back-exchange using acylimidazole reagents.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150509
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  • 59
    Digitale Medien
    Digitale Medien
    252CF plasma desorption mass spectrometry of a polycyclic peptide antibiotic, Nisin (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 305-310 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polycyclic peptide antibiotic, Nisin, has been analysed by plasma desorption mass spectrometry using two different sample preparation techniques and two versions of the commercial plasma desorption mass spectrometer, and a prototype with high resolving power. The spectra obtained allow identification of a major component and two minor analogues. Extensive fragmentation is observed in samples prepared by the electrospray technique, whereas only ions indicating the molecular weight are produced when the sample is adsorbed on nitrocellulose.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150602
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  • 60
    Digitale Medien
    Digitale Medien
    Gas chromatography/mass spectrometry and gas chromatography/mass spectrometry/mass spectrometry of methyl ester/methoxime/trimethylsilyl ether derivatives of thromboxanes (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 139-142 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron impact mass spectra of methyl ester/methoxime/trimethylsilyl ether derivatives of thromboxane B2 (TxB2) and 2,3-dinor-TxB2 and methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 are presented. Additionally, the derivatives of (2H4)-thromboxanes and methyl ester (2H3)-methoxime/trimethylsilyl ether derivatives of TxB2 and 2,3-dinor-TxB2 and (2H3)-methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 were investigated. Collision-induced dissociation mass spectra of the most intense parent ion in the high-mass region were taken. Collisionally activated decomposition mass spectra of the [C(12)-C(20)]+ ion of TxB2 and 2,3-dinor-TxB2 show an intense but not specific daughter ion, whereas the collison-induced dissociation mass spectrum of the [M - (C(16)-C(20)]+ ion of 11-dehydro-TxB2 results in the formation of numerous daughter ions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150304
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  • 61
    Digitale Medien
    Digitale Medien
    Collisional spectroscopy as a screening procedure for the determination of 2-(2-furoyl)-4(5)-(2-furanyl)-1H-imidazole from acid hydrolysis of B-poly(L-Lysine) and B-albumin (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 7-11 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The direct determination of 2-(2-furoyl)-4(5)-(2-furanyl)-1H-imidazole (FFI), present in the acid hydrolysis products of B-poly(L-lysine) and B-albumin and which appears to be a key intermediate in the physicochemical changes occurring during the incubation of protein with glucose, has been carried out by collisional spectroscopy, using a commercial double-focusing, reverse-geometry mass spectrometer and without any sample derivatization and chromatographic separation procedures.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150103
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  • 62
    Digitale Medien
    Digitale Medien
    A gas chromatographic/mass spectrometric screening, confirmation, and quantification method for estrogenic compounds (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 45-56 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method is described for the screening, quantification and confirmation of a variety of estronenic substances in animal tissues. A solid-phase extraction technique combined with a liquid/liquid extraction allows for rapid sample preparation and high throughput for the following compounds in bovine liver, muscle and kidney: diethylstilbestrol, dienestrol, hexestrol, zeranol, taleranol, zearalanone, zearalenone, zearalenol, estradiol and estriol. Gas chromatography/mass spectrometry and selected ion monitoring is used for the determination with detection limits ranging from 50 to 150 ppt.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150107
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  • 63
    Digitale Medien
    Digitale Medien
    Packed column supercritical fluid chromatography/mass spectrometry using a thermospray source in the filament-on mode (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 105-109 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Combined packed column supercritical fluid chromatography/mass spectrometry has been effected using a thermospray ion source in the filament-on mode. If organic modifiers are used with carbon dioxide as the supercritical mobile phase, chemical ionization mass spectra are obtained. With carbon dioxide electron impact type mass spectra are obtained. The potential of the system is illustrated with studies of mixtures of carbamate and organochlorine pesticides and a crude ergot fermentation extract.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150208
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  • 64
    Digitale Medien
    Digitale Medien
    The identification of biologically important thiols (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 123-128 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new mass spectral method has been developed and used to identify biologically important thiols. This method is based upon the use of C-14 labeled N-para-bromophenylmaleimide (BPM) to selectively derivatize thiols. The isotopic label facilitates the isolation and purification of trace quantities of the maleimide thiol adducts by high performance liquid chromatography (HPLC) with radioactivity detection. The use of the bromine atom in the thiol derivative greatly enhances the detectability of the parent and fragment ions containing the BPM moiety because of the generation of the characteristic N + 2 doublet ions. Several examples of the use of this method to identify non-volatile thiol peptides such as glutathione (GSH) and homoglutathione (hGSH) by fast atom bombardment mass spectrometry (FAB-MS) are described in this report.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150302
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  • 65
    Digitale Medien
    Digitale Medien
    In vivo metabolism of (+)-trans-Delta-9-tetrahydrocannabinol in the mouse (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 117-122 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (+)-trans-Delta-9-tetrahydrocannabinol [(+)-delta-9-THC], a biologically inactive isomer of (-)-trans-delta-9-THC, the major psychoactive constituent of cannabis, was administered intraperitoneally to male Charles River CD-1 mice; hepatic metabolites were extracted with ethyl acetate and isolated by chromatography on Sephadex LH-20 in chloroform. The metabolites were converted into trimethylsilyl (TMS), 2H9-TMS and methyl ester/TMS derivatives for examination by gas chromatography/mass spectrometry and additional samples were prepared by reduction of metabolic fractions with lithium aluminium deuteride. Sixteen metabolites were characterized: these were alcohols and carboxylic acids, together with several of their hydroxylated analogues. The major biotransformation pathway was hydroxylation at C(11) to give the major metabolite, followed by oxidation of this compound to a carboxylic acid. Hydroxylated analogues of these two compounds were substituted mainly in the side-chain. Although metabolism was very similar to that of the naturally occurring (-)-isomer as far as positions of substitution were concerned, some differences were observed. These related mainly to the positions of hydroxylation on the side-chain, where 1′-hydroxylation was preferred to hydroxylation at the 2′-position. The major difference in metabolism between the two isomers was that much less oxidation of the 11-hydroxy group to a carboxylic acid occurred and there was less hydroxylation at the 8-position. Thus, 11-hydroxy-(+)-trans-delta-9-THC was the major metabolite and most other metabolites were hydroxylated derivatives of this compound.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150210
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  • 66
    Digitale Medien
    Digitale Medien
    Negative ion chemical ionization gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry of prostanoid pentafluorobenzyl ester/methoxime/trimethylsilyl ether derivatives (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 143-151 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Negative ion chemical ionization mass spectra of prostaglandin F2α, prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1α, 2,3-dinor-6-oxo-prostaglandin F1α, thromboxane B2, 2,3-dinor-thromboxane B2, and 11-dehydro-thromboxane B2 pentafluorobenzyl ester (PFB)/methoxime/trimethylsilyl ether derivatives are presented. Collisionally activated decomposition mass spectra of the [M - PFB]- ions at collision energies of 8-24 eV and argon collision gas pressures of 1-2 mTorr almost show only fragmentation of trimethylsilanol, (CH3)2Si=CHOH, (CH3)2Si=CH2 and methanol whereas, except for carbon dioxide loss, only few low-intensity fragments from the carbon skeleton of the prostanoids are observed.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150305
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  • 67
    Digitale Medien
    Digitale Medien
    Continuous flow fast atom bombardment liquid chromatography/mass spectrometry: Studies involving conventional bore liquid chromatography with simultaneous ultraviolet detection (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 179-182 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A conventional bore liquid chromatograph has been interfaced to quadrupole and magnetic sector mass spectrometers configured for fast atom bombardment ionization via a continuous flow FAB probe. It is shown that post-column addition of FAB matrix and in-line ultraviolet detection facilities do not significantly compromise chromatographic integrity and that high quality mass spectra are obtainable from such FAB LC/MS studies.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150310
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  • 68
    Digitale Medien
    Digitale Medien
    Rapid identification of drug metabolites with tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 193-204 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method which involves the use of tandem mass spectrometry (MS/MS) for the identification of drug metabolites has been demonstrated with a triple quadrupole mass spectrometer. The method is based on the fact that metabolites usually retain various substructures of the original drug molecule. MS/MS is capable of rapidly identifying molecules with characteristic substructures without prior separation. It is shown that this method makes it possible to postulate possible drug metabolite structures rapidly and systematically without the use of standards. The MS/MS method, as it was applied to the identification of the metabolites of a new antiepileptic drug, zonisamide, is discussed. In this case it was possible to identify isomeric metabolites due to their differences in vaporization times off the probe and their different daughter spectra. The complementary uses of the neutral loss and parent scans for the determination of the site of metabolism is demonstrated. A new figure of merit, the limit of identification, is introduced. The amount of the epoxide metabolite of carbamazepine necessary for its reliable identification in urine was shown to be 0.4 ng/μl. The application of various techniques to confirm preliminary findings with this MS/MS method are described.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150403
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  • 69
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988) 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150101
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  • 70
    Digitale Medien
    Digitale Medien
    Mass spectral investigations on trichothecene mycotoxins IV - collisionally activated dissociation mass spectra (negative ion) of some macrocyclic trichothecenes (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 13-24 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Macrocyclic trichothecenes are di- and triesters of simple trichothecenes such as verrucarol and oxygenated verrucarols. They form the negatively charged molecular (M-·) ions more effectively than the positively charged protonated molecules under chemical ionization (methane) conditions. This is proposed to be due to extended conjugation at the macrocyclic ester bridges of the molecules. The M-· ions of several macrocyclic trichothecenes undergo collisionally activated dissociation (argon) yielding the daughter ions characteristic of the ester bridges. Structures for various specific and abundant ions observed in the tandem mass spectra are proposed. The daughter ions and experimental conditions for the specific detection of these trichothecenes are selected. A semi-synthetic macrocyclic trichothecene is found to be an adequate internal standard for the analysis of macrocyclic trichothecenes under collisionally activated dissociation (CAD) conditions. Low nanogram (1-2) quantities of roridin H and satratoxins are detected under these conditions. Preliminary results indicate the applicability of this negative ion chemical ionization/tandem mass spectrometric method for the analysis of macrocyclic trichothecenes in real samples.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150104
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  • 71
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988) 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150201
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  • 72
    Digitale Medien
    Digitale Medien
    Evaluation of the quantitative analysis of a steroid sulphate using fast atom bombardment and tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 99-104 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dehydroepiandrosterone sulphate (DHAS) has been quantified in human blood serum by fast atom bombardment (FAB)/tandem mass spectrometry of immunoadsorption extracts. FAB of DHAS yielded abundant ions corresponding to the intact steroid sulphate; these were selected by a double-focusing mass spectrometer prior to collisionally activated decomposition in a quadrupole collision cell and mass analysis by a quadrupole mass filter. [HSO4]- (m/z 97) was the sole prominent daughter ion. For quantitative analyses the quadrupole mass filter was set to transmit m/z 97 and a narrow-range magnet scan yielded a spectrum of parents, including m/z 367 and 369, corresponding to DHAS and the (2H2)-analogue (used as internal standard), respectively. Serum concentrations by this procedure were in good agreement with data obtained by gas chromatographic/mass spectrometric analyses of DHA heptafluorobutyrate, formed by direct derivatization of the steroid sulphate.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150207
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  • 73
    Digitale Medien
    Digitale Medien
    Determination of sodium salts of monensins A and B in the premix and the fermentation broth by electron impact mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 153-156 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron impact mass spectrometry has been used to determine the ratio of monensin A and B, and monensin A with monensin B as an internal standard in extracts of the premix and the fermentation broth. From the data obtained the total amount of monensin A and B was calculated and compared with the results of photometric determination. The relative width of the confidence intervals for the determination of monensin A and B ratio was 2% (2%) in the premix (fermentation broth), 5% (7%) for monensin A, 13% (14%) for monensin B and 5% (6%) for the total amount of monensins A and B. The limit of determination of monensins was about 100 ng. The difference in the results of photometric and mass spectrometric determination was significant for fermentation broth. No significant difference was found in the premix.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150306
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  • 74
    Digitale Medien
    Digitale Medien
    A mass spectral study of cyclophosphamide concerning a thermally induced rearrangement reaction (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 163-173 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron impact mass spectra of cyclophosphamide (1) are very sensitive towards experimental conditions in view of the kind of sample handling, the type of mass spectrometer used and the temperature of evaporation. The reason for this phenomenon is the elimination of HCl from the molecular ion by a specific 1,5-hydrogen transfer yielding an ion at m/z 224 which is structurally related to the bicyclic compound 4 with its typical fragment ions at m/z 175 and 147. Thermal excitation of the sample increases the intensity of this fragmentation pathway. The fragmentation pattern of 1 and the thermally induced rearrangement reaction has been elucidated by means of isotopic labelling, high-resolution data, metastable ion analysis and some tandem mass spectrometric experiments. Various samples of 1 monohydrate and its commercially available preparations, which are triturates with sodium chloride, differing in the crystal size distribution, showed nearly identical mass spectra on two different magnetic mass spectrometers, provided that the materials were introduced as solids under careful control of the evaporation temperature. The fragmentation via m/z 224 prevails in case of non-crystalline, pre-dissolved samples on one of the instruments used which might be explained by a differing construction of the ion source and the sample cup holder. The conclusions of Mruzek et al. concerning different proportions of stereoisomers in pharmaceutical preparations of 1 lack any analytical evidence.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150308
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  • 75
    Digitale Medien
    Digitale Medien
    B. A. Garetz and J. R. Lombardi. Advances in laser spectroscopy, volume 3. J. Wiley & Sons, Ltd. 1986 ISBN 0-471-90990-A £33.50 (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 183-183 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150312
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  • 76
    Digitale Medien
    Digitale Medien
    Identification of metabolites of tiropramide in human urine (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 205-209 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metabolites of tiropramide were extracted from the urine of healthy volunteers given tiropramide hydrochloride orally. Eight metabolites of tiropramide were found by gas chromatography/mass spectrometry. Three were identified on the basis of their mass spectra, retention times and comparison with synthetic standards. For the others a probable structure is proposed on the basis of their mass spectra.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150404
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  • 77
    Digitale Medien
    Digitale Medien
    Mass spectrometric characterization of some human metabolites of flumecinol (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 229-232 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mass spectrometric behaviour of six human metabolites formed by hydroxylation in various positions of the α-ethyl group or/and on the phenyl ring of 3-trifluoromethyl-α-ethyl-benzyhydrol (flumecinol) and seven related compounds has been studied. The electron impact mass (EI) spectra of these compounds show significant and characteristic effects of substituents, but many of them suffer from weakness or even from absence of the M+· peak owing to the very facile primary loss of the α-aliphatic chain, i.e. no direct information can be obtained about the size of the molecule and that of this chain. It is demonstrated for derivatives possessing a hydroxylated α-ethyl group that the difficulties in structural characterization due to the lack or weakness of M+· and [M + H]+ peaks in their EI and chemical ionization mass spectra, respectively, can be overcome by studying their silylated or boronated derivatives. Furthermore, silylation enables us to obtain a clear base for distinction of the primary and secondary alcohols of this type.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150407
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  • 78
    Digitale Medien
    Digitale Medien
    Synthesis of deuterium-labelled elliptinium and its use in metabolic studies (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 243-247 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 9-hydroxy-2-(U-2H3) methylellipticinium acetate (elliptinium) was synthesized with an isotopic purity of at least 96%. The structure was confirmed by proton nuclear magnetic resonance and direct probe fast atom bombardment mass spectrometry. A mixture of elliptinium and its deuterated analogue was administered intravenously to rats. In urine, after analysis by liquid chromatography/mass spectrometry (LC/MS), unchanged drug and N-acetylcysteinylelliptinium were found. In bile, after ion-pair extraction and LC/MS, the glutathionyl-elliptinium was found in addition to the parent drug and the N-acetylcysteine adduct.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150502
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  • 79
    Digitale Medien
    Digitale Medien
    Determination of boldenone sulfoconjugate and related steroid sulfates in equine urine by high-performance liquid chromatography/tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 283-289 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Sulfoconjugated anabolic steroids were separated by micro-bore high-performance liquid chromatography. The eluent was introduced into the atmospheric pressure ion source of the triple-quadrupole mass spectrometer via an ion spray liquid chromatograph/mass spectrometer interface operated in the negative ion mode. The limit of detection was 10 pg on-column by selected ion monitoring of the molecular ion and the response increased linearly over a concentration range of 2.4 orders of magnitude. Following work-up by a liquid-solid extraction procedure of equine urine samples, full-scan daughter ion spectra of boldenone sulfate could be obtained up to 17 days after a therapeutic dose of boldenone undecylenate to a horse.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150508
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  • 80
    Digitale Medien
    Digitale Medien
    Laser desorption/fourier transform ion cyclotron resonance mass spectrometry: Digoxin, digitoxin, and their reduced and sugar-hydrolyzed metabolites (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 295-302 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Mass spectra of digoxin and digitoxin (the most widely prescribed drugs for treatment of congestive heart failure) and a complete set of their 14 dihydro- and sugar-hydrolyzed metabolites have been obtained via laser desorption/ionization with a Fourier transform ion cyclotron resonance (LD/FT/ICR) mass spectrometer. The most intense peak is typically the pseudomolecular [M + K]+ ion, but fragment ions corresponding to loss of 1--3 sugars and hydroxyls are also observed. LD/FT/ICR mass spectra for all 16 compounds were produced with a single set of sample and spectrometer parameters. No matrix peaks are present. Finally, LD/FT/ICR provides dynamic mass accuracy within ≈5 ppm throughout a mass range of 404 〈 m/z 〈 819.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150510
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  • 81
    Digitale Medien
    Digitale Medien
    Conjugation reactions of polyaromatic quinones to mono- and bisglutathionyl adducts: Direct analysis by fast atom bombardment mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 329-332 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The conjugation products of several reactive quinones with glutathione have been identified by fast atom bombardment mass spectrometry. Appropriate conditions have been developed which enabled the direct, dynamic mass spectral analysis of spontaneous, as well as glutathione transferase catalysed conjugation reactions. Applications to a series of quinones provided the direct detection and differentiation of the formation of mono- and bisglutathionyl adducts between regioisomeric quinone substrates in that only 1,4-quinones yielded bisglutathionyl adducts, which were not observed for the 1,2-isomers.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150605
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  • 82
    Digitale Medien
    Digitale Medien
    Collisional spectroscopy in structural characterization of melanins 2 - laser desorption experiments on bio- and synthetic tryptophan melaninsFor part 1 see Ref. 13. (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 353-355 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Melanins1 are naturally occurring macromolecules whose structural complexity appeared evident from the first researches of Quilico.2 Their structural characterization remains a difficult problem, mainly due to the physico-chemical properties of such compounds. Melanins are insoluble in organic solvents as well as aqueous solutions and are infusible. Consequently the traditional chemical degradation and physicochemical methods such as ultraviolet, infrared, 1H and 13C nuclear magnetic resonance, ESR (electron spin resonance), XPS (X-rays photoelectron spectroscopy) and X-ray diffraction have led, until now, to limited information on melanin chemical structure1,3.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150608
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  • 83
    Digitale Medien
    Digitale Medien
    Automated measurement of the concentration and 13C enrichment of carbon dioxide in breath and blood samples using the finnigan MAT breath gas analysis system (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 365-367 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The operation and performance of the Finnigan MAT automated Breath Gas Analysis System for the routine analysis of 13C breath tests taken in 20-ml Vacutainers is described. Up to four samples per hour can be analysed with a standard deviation of δ13C of 〈0.05%o being achieved over the range 10-50 μmol CO2. The equipment can also be used for the automatic measurement of the concentration and 13C enrichment of CO2 derived from carbonate or bicarbonate solutions, including blood and other physiological fluids.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150703
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  • 84
    Digitale Medien
    Digitale Medien
    FAB and tandem mass spectrometry for endorphin- and ACTH peptides of molecular weight to 2000 (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 649-657 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Four β-endorphins (β-endorphin 6-17, 2-17, 1-16, and 1-17) and two adrenocorticotropic hormone (ACTH) peptides (ACTH 1-10 and (1-16)-NH2) were studied by using fast atom bombardment coupled with tandem mass spectrometry. The capability to reproduce metastable ion and collisionally activated decomposition spectra on two different commercial sector mass spectrometers in two different laboratories was found to be acceptable (deviations in relative abundance are less than ± 50%). The endorphin peptides fragment metastably or upon collisional activation to give abundant B-series ions as well as Y-series ions, whereas Y-series ions are the principal ionic species produced upon the desorption by fast atom bombardment. The ACTH peptides also fragment to give Y-series ions, but of relatively low abundance compared to those from the endorphins. For both sets of peptides, high-energy collisionally activated decomposition and metastable ion decomposition daughter ion spectra are precise, structurally informative - even for peptides up to m/z 2000 - and complementary to spectra of daughter ions produced by desorption ionization alone.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151203
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  • 85
    Digitale Medien
    Digitale Medien
    Analysis of sub-microgram quantities of nucleotides by fast atom bombardment mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 547-551 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Nucleotides of the structure P1,Pn-di(adenosine-5′)-n-phosphate (n = di- through penta-) in the form of salts, and P1,P4-di(guanosine-5′)tetraphosphate sodium salt have been analyzed by fast atom bombardment (FAB) mass spectrometry. A 0.2 molar solution of p-toluenesulfonic acid in glycerol has been evaluated as a matrix. In this matrix, the metal ions of the nucleotide salts are readily exchanged for protons, resulting in a simple spectrum with only one peak in the molecular ion region corresponding to the free phosphoric acid of the nucleotide plus or minus a proton (positive or negative mode), instead of the multiplicity of peaks arising from a series of metal and matrix adduct ions found with glycerol as matrix. The detection limit for analytes using this matrix is improved by a factor of ten compared to glycerol alone. It appears that the high acidity and the surfactant properties of p-toluenesulfonic acid both contribute to this result. Useful spectra are obtained from 250 ng of each of the above mentioned nucleotides, with the detection limit being somewhat lower in the positive mode. However, both positive and negative FAB spectra are useful and the results are complementary.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151007
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  • 86
    Digitale Medien
    Digitale Medien
    Nucleophilic reactions between biological conjugates and tetraalkylammonium ion pair reagents during desorption chemical ionization (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 571-576 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tetraalkylammonium salts, commonly used as ion pair reagents in chromatography, were found to react with biological conjugates under desorption chemical ionization conditions in a mass spectrometer. The reactions occur for aromatic glucuronide and glucoside conjugates using solid samples loaded on the direct exposure probe. Evidence is presented that several mechanisms contribute to the degradative alkylation of benzo(a)pyrene glucuronide. This undesirable process can be prevented by using ammonium or trialkylammonium instead of tetra-alkylammonium salts in the chromatographic separation. Nucleophilic attack on the tetraalkylammonium cations in the energized condensed phase was found to occur also for some simpler aromatic compounds.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151010
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  • 87
    Digitale Medien
    Digitale Medien
    A rapid method for the structural characterization of sulphated phlorotannins by negative ion fast atom bombardment mass spectrometry and acetylation on the target (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 595-602 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method for a rapid and direct structural determination of sulphated phlorotannins has been developed by using a combination of negative ion fast atom bombardment mass spectrometry and acetylation on the target. The structural variations of sulphated phlorotannins include: (i) the number of monomeric phloroglucinol units involved; (ii) the mode of their connectivity; (iii) the orientation of hydroxy groups on aromatic carbon atoms; (iv) the presence of the substituents other than hydroxy groups on aromatic carbon atoms; and (v) the number of sulphate esters on the hydroxy groups. Additionally, the acidic protons on the sulphate groups can be easily substituted by sodium or potassium cations, depending on the mode of isolation. In the negative ion mode, several ions were observed and a determination of molecular size and molecular parameters (i)-(v) appeared to be rather speculative. After adding diluted hydrochloric acid to the sample in order to substitute alkali ions for protons, the hydrolysis of sulphate groups has been observed. The acetylation on the target, however, represents a rapid method to observe the molecular ions, and from the mass differences the molecular parameters can be easily calculated. This procedure also demonstrates the general possibility of studying rapid chemical reactions by fast atom bombardment mass spectrometry.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151104
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  • 88
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988) 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151201
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  • 89
    Digitale Medien
    Digitale Medien
    The use of alkoxycarbonyl derivatives for the mass spectral analysis of drug-thioether metabolites. Studies with the cysteine, mercapturic acid and glutathione conjugates of acetaminophen (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 637-647 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkoxycarbonyl derivatives of the cysteine-, N-acetylcysteine- and glutathione conjugates of acetaminophen have been prepared in aqueous buffer solutions and their chromatographic and mass spectrometric properties examined. Structurally informative fragmentation patterns of the cysteine- and N-acetylcysteine derivatives were obtained when their methyl esters were subjected to analysis by direct insertion chemical ionization (CH4) mass spectrometry, although field desorption and liquid secondary ion mass spectrometric techniques were required in order to obtain satisfactory spectral data for derivatives of the glutathione adduct. Treatment of ethoxycarbonyl derivatives of the three acetaminophen metabolites with N-methyltrifluoroacetamide-based silylating reagents led to the formation of a common volatile product which was ideally suited to analysis by gas chromatography/electron impact mass spectrometry. A mechanism is proposed for the formation of this novel derivative, which appears to possess a benzo-1,3-thioxalane structure, and its mass spectral characteristics are reported. Finally, the utility of alkoxycarbonyl derivatives for the analysis of drug - thioether conjugates in biological fluids is discussed in terms of their advantages for aqueous phase derivatization, purification by high-performance liquid chromatography and characterization by mass spectrometry.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151202
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  • 90
    Digitale Medien
    Digitale Medien
    Bromo- and bromochloro-polynuclear aromatic hydrocarbons, dioxins and dibenzofurans in municipal incinerator fly ash (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 669-676 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A fly ash sample found to contain polychlorinated dioxins and dibenzofurans was analyzed for brominated analytes. Bromochloro-polynuclear aromatic hydrocarbons, dioxins and dibenzofurans, as well as bromo PAH were found in ppt to ppb concentrations. Analytical results were confirmed by high-resolution mass spectrometric accurate mass determinations and by tandem mass spectrometry.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151205
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  • 91
    Digitale Medien
    Digitale Medien
    Fast atom bombardment mass spectrometry of protected peptide segments (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 681-684 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200151207
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  • 92
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988) 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020101
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  • 93
    Digitale Medien
    Digitale Medien
    Diary (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. i 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020102
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  • 94
    Digitale Medien
    Digitale Medien
    Identification and substructure analysis of oligosaccharide chains derived from glycoproteins by computer retrieval of high-resolution 1H-NMR spectra (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 11-27 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Oligosaccharides ; Glycoproteins ; Identification ; Substructure analysis ; High-resolution ; 1H-NMR spectra ; Computer retrieval ; Reproducibility ; Chemical shifts ; Similarity index ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Based on a statistical model of the reproducibility of NMR spectral features, a system for computer retrieval of high-resolution 1H-NMR spectra of glycoprotein carbohydrates has been developed. For corresponding peaks in an unknown and a reference spectrum, a similarity index based on the reproducibility of the chemical shifts is calculated. In addition, a second similarity index, based on the probability distribution of the percentage of non-matching peaks, has been developed. From these two similarity indices, a combined similarity index using the recall-reliability function as the optimizing criterion has been derived.First results indicate that the ‘1H-NMR reproducibility-based retrieval’ (‘1HRR’) system offers good perspectives for both identification and substructure analysis.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020104
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  • 95
    Digitale Medien
    Digitale Medien
    Chance classifications by non-parametric linear discriminant functions (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 1-10 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Linear discriminant functions ; Pattern recognition ; Monte Carlo simulations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In applications of pattern recognition techniques to problems in chemical fingerprinting, only limited knowledge about the underlying statistical distribution of the data is generally available. This means that non-parametric methods must be used. Non-parametric discriminant functions have been used to provide insight into relationships contained within sets of chemical measurements. However, classification based on random or chance separation can be a serious problem. Monte Carlo simulation studies have been carried out to assess the probability of chance classification for non-parametric linear discriminants. The level of expected chance classification is a function of the number of observations (the number of samples), the dimensionality of the problem (the number of independent variables per observation), class membership distribution and the covariance structure of the data being examined. An approach for assessing the level of significance of classification scores obtained from real training sets will be presented. These simulation studies establish limits on the approaches that can be taken with real data sets so that chance classification are improbable, and provide information necessary for integrating the data analysis into the overall experimental design.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020103
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  • 96
    Digitale Medien
    Digitale Medien
    Taxonomy based on chemical constitution: Differentiation of Africanized honey-bees from European honey-bees (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 29-37 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Pattern recognition ; Principal component analysis ; Linear discriminant analysis ; Classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Gas chromatography and pattern recognition methods have been used to develop a potential method for differentiating between European and Africanized honey-bees based on chemical constitution. 243 European, African and Africanized honey-bees were characterized by 40-peak GCs of cuticular hydrocarbon extracts. Discriminants were developed that correctly classified the bees, and these discriminants were used successfully to classify bees of unknown origin, including hybrids.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020105
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  • 97
    Digitale Medien
    Digitale Medien
    Expert system for knowledge-based modelling of analytical laboratories as a tool for laboratory management (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 49-65 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Laboratory organization ; Expert systems ; Digital simulation ; Decision support ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An expert system (LABGEN) is presented for decision support in analytical laboratories by means of digital simulation. In an interactive manner, LABGEN constructs simulation models of laboratory organizations. It makes use of a database of model fragments and applies rules in order to prevent the user providing redundant information and to prevent inconsistent models being constructed. The models are written in the dedicated simulation language SIMULA. After compilation they can be used for simulation experiments. LABGEN can be applied to a wide range of laboratory organizations. An example of the application of LABGEN is presented.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020107
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  • 98
    Digitale Medien
    Digitale Medien
    Selection of optimal regression models via cross-validation (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 39-48 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Regression modelling ; Cross-validation ; Bootstrap ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A general problem arising in the development of regression models is the selection of the optimal model. Whenever a feature selection procedure, such as step forward, backward elimination, best subset or all possible combinations, or when a data compression approach, such as principal components or partial least-squares regression, is used, the question of how many regression terms to include in the final model must be addressed.This work describes the evaluation of four different criteria for selection of the optimal predictive regression model using cross-validation. The results obtained in this work illustrate the problems which can arise in the analysis of small or inadequately sampled data sets. The common approach, selecting the model which yields the absolute minimum in the predictive residual error sum of squares (PRESS), was found to have particularly poor statistical properties. A very simple change to a criterion based on the first local minimum in PRESS will provide a significant improvement in the cross-validation result. A criterion based on testing the significance of incremental changes in PRESS with an F-test may provide more robust performance than the local minimum in PRESS method.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020106
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  • 99
    Digitale Medien
    Digitale Medien
    The effect of interferences and calbiration design on accuracy: Implications for sensor and sample selection (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 67-79 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Experimental design ; Multivariate calibration ; Variable selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methods of multivariate calibration use models that relate spectral data or sensor array responses to the concentrations of analytes. The goal is to insure that the calibration model can accurately estimate analyte concentrations in unknown samples not contained in the calibration set. The sensors or spectral channels (e.g. wavelengths) selected for incorporation in the model, as well as the samples selected for the calibration step, are known to have an effect on the accuracy of analysis for unknown samples. This work provides a fundamental treatment of this effect and derives criteria for optimal selection. Additionally, a proof is given for the advantage of having more sensors and calibration samples than analytes - the overdetermined case.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020108
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  • 100
    Digitale Medien
    Digitale Medien
    Monte Carlo studies of non-parametric linear discriminant functions (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 85-89 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Linear discriminant functions ; Pattern recognition ; Monte Carlo simulations ; Chance classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Classification rules using non-parametric linear discriminant functions are often developed from training sets that are not linearly separable. In these situations it is a common practice among inexperienced workers to use many different pattern recognition methods and then select the results that look the best. However, this practice will only increase the risk of spurious results. To document this, we recently carried out a series of Monte Carlo simulation studies to assess the level of chance classification for two different classification algorithms. The level of chance classification for a given dichotomy is found to vary with the choice of the non-parametric linear discriminant function employed. Although previous workers have indicated that the degree of separation in the data due to chance is only a function of the object-to-descriptor ratio, the results of this study suggest otherwise.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180020110
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