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  • 1995-1999  (263)
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  • 1
    ISSN: 1437-160X
    Keywords: Rheumatoid pannus ; Adhesion molecules ; β1 integrins ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate the mechanism of synovial pannus formation in rheumatoid arthritis, immunohistochemical and immunoelectron microscopic studies with monoclonal antibodies against the adhesion molecules, CD54 (ICAM-1), CD 11a (LFA-1), CDw49a (VLA-1), CDw49b (VLA-2), CDw49c (VLA-3), Cdw49d (VLA-4) and CDw49e (VLA-5), were carried out to determine the pattern of distribution of these molecules at the rheumatoid synovial cartilage junction. Treatment with anti-ICAM-1 resulted in membrane staining of most of the macrophages and fibroblasts infiltrating the synovial tissue and bordering the pannus-cartilage junction, suggesting the possibility that ICAM-1 may function to facilitate the adhesion of synovial type A cells bearing ICAM-1 to type B cells of the pannus. ICAM-1-positive macrophages and fibroblasts were often found to be in contact with lymphoid cells, suggesting also that a cellular immune reaction occurs in the formation of the pannus. In addition, VLA-3, VLA-4 and, particularly, VLA-5 were the predominantβ1 integrins expressed by rheumatoid synovial pannus. Since these three integrins all function as fibronectin receptors, it is possible that the fibronectin-rich environment of the rheumatoid cartilage surface effectively traps pannus cells expressing high levels of these molecules. The VLA-5 molecule was found in a pericellular and interterritorial matrix distribution in the present study, strongly suggesting that a recepfor-ligand interaction between VLA-5 and cartilage matrix may occur at the early stage of pannus formation. Furthermore, an increase inβ1 integrin may be necessary for the growth of the pannus and also for the upregulation of the VLA molecules, leading secondarily to increased attachment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Neurosurgical review 19 (1996), S. 39-42 
    ISSN: 1437-2320
    Keywords: Electron microscopy ; immunohistochemistry ; meningeal melanocytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of cervical juxtamedullary meningeal melanocytoma is presented along with results of careful neuroradiological and pathological examinations. The authors review the previous literature and discuss the problems related to the intriguing diagnosis of this very rare entity. CT and MRI show variable appearances due to different degrees of melanization and do not reliably allow us to distinguish meningeal melanocytomas from other pigmented tumors. Pathological examination of the tumor is critical for diagnosis, but is absolutely must comprise electron microscopy and immunohistochemistry. Immunohistochemical and ultrastructural criteria are thus proposed to distinguish meningeal melanocytoma from pigmented meningioma or schwannoma and malignant melanoma (primary or secondary).
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0423
    Keywords: Schlüsselwörter Makulaforamen ; Epiretinale Membran ; Elektronenmikroskopie ; Vitrektomie ; Pathogenese ; Key words Macular hole ; Epiretinal membrane ; Electron microscopy ; Vitrectomy ; Pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Anteroposterior and tangential traction on the central retina is an important factor in the pathogenesis of idiopathic macular hole formation. Histological studies have shown that macular holes of different stages can be associated with epiretinal membranes. Such membranes can be removed during surgery for macular holes. We investigated such tissue samples of 11 patients with macular holes in stages II – IV. Light microscopially, the tissue consisted of a thin collagen layer mostly covered by a thin layer of cells. Ultrastructural analysis revealed glial cells and macrophages as cellular components. The collagen can be ascribed to vitreous, inner limiting membrane and newly formed collagen. According to the morphological findings a multilayered tissue structure can be assumed. Macrophages were found on the retinal side of the inner limiting membrane and at the vitreal side of the tissue. Therefore, the macrophages probably originate from the retina as well as from the vitreous as so-called resident hyalocytes. Glial cells covered the inner limiting membrane forming pericellular collagen to which outer vitreous collagen fibrils can be attached. The multilayered membrane structure might possibly be the cause for only partial laminar surgical extraction so that contractile or potentially proliferative tissue residues might be one of the reasons for surgical failures after incomplete membrane peeling.
    Notes: A.-p. und tangentiale Traktionen an der zentralen Netzhaut spielen für die Entstehung idiopathischer Makulaforamina eine wichtige Rolle. Durch histologische Untersuchungen ließen sich bei Makulaforamina unterschiedlicher Stadien epiretinale Membranen nachweisen, die für die tangentiale Traktion auf die Foramenränder verantwortlich gemacht werden. Von 11 Patienten konnten wir derartige, von uns chirurgisch entfernte Membranen licht- und elektronenmikroskopisch untersuchen. Die Membanen bestehen lichtmikroskopisch aus einem azellulären Kollagenband mit einem schmalen, teilweise nur einschichtigen Zellbesatz. Elektronenmikroskopisch lassen sich als zelluläre Komponenten Gliazellen und Makrophagen differenzieren. Die Kollagenanteile sind Glaskörperkollagen, neugebildetem Kollagen und der Lamina limitans interna zuzuordnen. Aus den Befunden läßt sich eine Schichtung der Membranen rekonstruieren mit sublaminären Makrophagen, der Lamina limitans interna und epilaminären Gliazellen und vereinzelten Makrophagen, die am ehesten residenten Hyalozyten entsprechen. Auf der vitrealen Seite können auch Verbindungen der Membran zum äußeren Glaskörperkollagen bestehen. Die Membranen zeigen Charakteristika, die in ihrem Aufbau epiretinalen Proliferationsmembranen entsprechen. Die topographische Schichtung der Membranen könnte zur Folge haben, daß chirurgisch teilweise nur Lamellen und nicht die gesamte Membran abgeschält werden. Kontraktions- oder auch proliferationsfähige Membranreste können dann einer der Faktoren für operative Mißerfolge sein.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 12 (1996), S. 49-53 
    ISSN: 1437-9813
    Keywords: Key words Silicone ; Silicon tubing ; Ivac 560 pump ; Energy-dispersive X-ray analysis (EDXA) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Migration of particulate matter from plastic tubing and solid plastic implants has been documented in a number of studies, including some with the use of cardiac bypass, haemodialysis, and pump-assisted intravenous infusions. In order to ascertain whether silicone embolisation occurs when children have an Ivac 560 pump-assisted IV infusion, we passed 180 ml of pumped fluid through a microfilter and compared the scanning electron micrographs of those filters with unused filters and with others through which a similar volume had been passed without using the pump. The particles on the filters were analysed for their elemental content using energy-dispersive X-ray analysis. In addition, the appearance of the silicone tubing used in the pump over 3 and 72 h was assessed and compared to that of flow-only and unused tubing. More particles were found on the microfilter when fluid had been delivered via the pump than on those through which non-pumped fluid had passed or that were unused. Elemental silicon-containing particles were only found on the filter when a pump had been attached to the IV line. The flow-only and unused tubing were found to have adherent particles on the inner surface that were not seen once the tubing had been used for 3 h in the Ivac 560 pump. Also, after 72 h use, the silicone tubing had a deformed inner layer. The clinical significance of these findings is yet to be determined, but it does appear that silicone embolisation occurs during pump-assisted infusions in children.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 12 (1996), S. 49-53 
    ISSN: 1437-9813
    Keywords: Silicone ; Silicon tubing ; Ivac 560 pump ; Energy-dispersive X-ray analysis (EDXA) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Migration of particulate matter from plastic tubing and solid plastic implants has been documented in a number of studies, including some with the use of cardiac bypass, haemodialysis, and pump-assisted intravenous infusions. In order to ascertain whether silicone embolisation occurs when children have an Ivac 560 pump-assisted IV infusion, we passed 180 ml of pumped fluid through a microfilter and compared the scanning electron micrographs of those filters with unused filters and with others through which a similar volume had been passed without using the pump. The particles on the filters were analysed for their elemental content using energy-dispersive X-ray analysis. In addition, the appearance of the silicone tubing used in the pump over 3 and 72 h was assessed and compared to that of flow-only and unused tubing. More particles were found on the microfilter when fluid had been delivered via the pump than on those through which nonpumped fluid had passed or that were unused. Elemental silicon-containing particles were only found on the filter when a pump had been attached to the IV line. The flow-only and unused tubing were found to have adherent particles on the inner surface that were not seen once the tubing had been used for 3 h in the Ivac 560 pump. Also, after 72 h use, the silicone tubing had a deformed inner layer. The clinical significance of these findings is yet to be determined, but it does appear that silicone embolisation occurs during pump-assisted infusions in children.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2307
    Keywords: Papillary adenoma of type II pneumocytes ; Immunohistochemistry ; Electron microscopy ; Morphometry ; Multivariate cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Papillary adenoma of type II pneumocytes is a rare tumour. It is considered to be a benign neoplasm and is derived from immature cells in the bronchioloalveolar epithelium, however, its biological nature has not been elucidated. We report a case of an adenomatous tumour; a papillary adenoma of type II pneumocytes, which we regard as possessing malignant potential. Light microscopically, as well circumscribed, papillary tumour of predominantly cuboidal cells resembling type II pneumocytes was found, but Clara type and ciliated cells were also present. Immunohistochemically, the tumour cells reacted positively with antibodies to surfactant apoproteins (A, B), carcinoembryonic antigen, cytochrome P-450 1A1-2 and 2B1-2. Ultrastructurally, many osmiophilic lamellar bodies and electron-dense granules were demonstrated. Semi-serial sections revealed signs of transbronchial dissemination and vascular invasion. Morphometry using 12-dimensional cluster analysis disclosed features of the tumour cells which resembled those of pneumocyte type II adenocarcinoma. These findings suggest that the present case has some malignant characteristics and originates from immature bronchiolar or alveolar cells, with a potential to develop into both type II pneumocyte and Clara cell type adenocarcinomas.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-0879
    Keywords: Interstitial stroma ; Carcinogenesis ; Bladder epithelium ; Neovascularization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study describes ultrastructural alterations of the interstitial stroma in the rat bladder epithelium during N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced bladder carcinogenesis using scanning (SEM) and transmission (TEM) electron microscopy with NaOH treatment. The results obtained with SEM demonstrated the occurrence and development of stroma protrusions which exhibited pipe-like structures in the rat bladder epithelium following administration of BBN. Number and size of blood vessel sections also gradually increased both in the stroma and within the layer of the proliferated epithelial cells as examined by light microscopy (LM) and TEM. In this study stroma alterations were not only observed in malignant lesions of rat bladder, but hyperplastic lesions were also accompanied by stroma alterations. It is suggested that: (1) the interstitial stroma of the rat bladder epithelium may exhibit pathological changes in structure and these changes may correlate with the progression of epithelial cell proliferation following administration of BBN and (2) one of the most important alterations in the stroma is the occurrence of neovascularization, which may induce structural modification of the stroma in the processes of bladder tumor growth and development.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 193 (1996), S. 331-339 
    ISSN: 1432-0568
    Keywords: Synapse ; Cell migration ; Olfactory neurons ; Electron microscopy ; Vomeronasal organ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rat neonate vomeronasal organs were transplanted into the parietal cortex of littermates to examine their survival and the behavior of axon growth into the surrounding host brain parenchyma. After survival times of 10–100 days the brains were processed for ultrastructural examination. The transplanted vomeronasal organs (VNO) formed several vesicles lined with a sensory epithelium. From these sensory epithelia, VNO neurons leave the epithelium and enter the host brain. Transplant neurons grew axons that fasciculated into bundles surrounded by sheath cell processes and formed one or more fiber plexuses containing distinct globose or spherical-shaped glomeralar-like structures. The glomeruli consisted of nerve terminals between which existed asymmetric synaptic contacts. Rarely did we observe clear reciprocal synapses. The glomeruli also contained terminals that showed signs of degeneration, such as increased density of the terminals, clumping of mitochondria and multivesicular bodies. The glomeruli were not partitioned or subdivided by glial septa; however, glial profiles were interspersed among the sensory terminals. Transplant glomeruli also lacked periglomerular cells and had no definitive glial envelope. These results suggest that glomerular formation is not dependent on dendrite contribution of second order neurons or glial support, but rather on a complementary population of receptor neurons.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0568
    Keywords: Thalamus ; Somatosensory system ; Synaptogenesis ; Nervous system ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electron microscopy has been employed to analyze the normal maturationai sequence that characterizes the postnatal development of synaptic circuits in the ventrobasal (VB) and reticular (Rt) thalamic nuclei of rats at different ages (from birth to the end of the third postnatal week). Throughout the first postnatal week, similar signs of immaturity are observed in both nuclei, mainly consisting in scarcity of cytoplasmic organelles, presence of wide extracellular spaces, and absence of myelinated fibers. Several synaptic terminals are however present from birth, thus indicating that some of the afferents have already reached and contacted their thalamic target during embryonic life. Most of the terminals are small and contain only a few round, clear vesicles, and therefore their cytological features do not allow the identification of their origin. In particular, in both nuclei, terminals with flat vesicles and symmetric specialization are only rarely observed, and in VB the ascending terminals are not distinguishable from terminals of other sources as they are in adults. During the second postnatal week, progressive maturationai changes in VB and Rt lead to neurons having well-developed cytoplasmic organelles and to an elaborate neuropil containing myelinated fibers and synaptic terminals that are morphologically heterogeneous and resemble the adult ones. The permanence of growth cone-like profiles and of numerous somatic and dendritic protrusions, often contacted by synaptic terminals, indicates that a certain degree of reorganization is still taking place in both nuclei. By the end of the third postnatal week the synaptic organization of VB and Rt is indistinguishable from that observed in adults. This ultrastructural study shows that the appearance of the neuropil of VB and Rt and the morphological complexity of the synaptic arrangements characteristic of the adult rat are not present in neonates, but are gradually acquired during the first three postnatal weeks, and that they result from progressive modifications in circuit organization involving both pre- and postsynaptic elements.
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  • 10
    ISSN: 1432-0533
    Keywords: Key words Fukuyama-type congential muscular ; dystrophy ; Fetus ; Cerebrocortical pathology ; Breaches in glia limitans ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A light and electron microscopic study of the brain of an 18-week fetus with a prenatal genetic diagnosis of Fukuyama-type congenital muscular dystrophy revealed a widespread mantle of abnormal neurogliomesenchymal tissue that covered a dysplastic cerebral cortex. In this area alone, the glia limitans that adjoined the abnormal mantle via one or two layers of basal lamina had frequent breaches, through which neuroglial elements extruded. In the most severely affected cortical region, which had only a rudimentary and fragmentary glia limitans, the majority of cortical neurons had migrated into the neurogliomesenchymal tissue. The massive overmigrated neurons still maintained a somewhat columnar arrangement, and the marked dysplasia abruptly shifted to a neurogliomesenchymal tissue-free normal cortical structure with an intact glia limitans, thus indicating essentially vertical overmigration of neurons without significant tangential migration of them. Together the above findings imply that breaches in the glia limitans may be the primary cause of the micropolygyria seen in this genetic disorder.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1432-0533
    Keywords: Key words Central neurocytoma ; Glial fibrillary acidic protein ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have identified two central neurocytomas which contained cells co-expressing glial fibrillary acidic protein and synaptophysin defined by double-label immunostaining. Dual-positive cells were mostly polygonal in shape and with a morphological appearence similar to that of reactive astrocytes. This distinct morphology could be used to distinguish cells expressing glial fibrillary acidic protein from cells with round and clear cytoplasm which did not express glial fibrillary acidic protein and which composed the majority of the tumor. Samples containing polygonal cells were selected for electron microscopy from toluidine blue-stained semithin sections. Ultrastructural findings were similar in both neurocytomas, with both being composed predominantly of round cells with clear cytoplasm corresponding to the clear cells identified by light microscopy. Dense-core vesicles and clear vesicles were frequently observed in the cell processes. Apart from these clear cells, polygonal cells with electron-dense cytoplasm were noted. Paralleling the results of double immunostaining, these polygonal cells contained both dense-core vesicles and intermediate, presumably glial filaments. Microtubules and lipofuscin granules were also observed. These results suggest that cells expressing glial fibrillary acidic protein in central neurocytoma include tumor cells with both neuronal and glial characteristics.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 193 (1996), S. 259-269 
    ISSN: 1432-0568
    Keywords: Stomach ; Parietal cell lineage ; Heterogeneity ; Electron microscopy ; Cattle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The origin and differentiation of the oxyntic cell lineage during physiological cell renewal was investigated by light and electron microscopy in the abomasal mucosa of adult cattle. The morphologically heterogeneous oxyntic cell population exhibits various developmental subtypes depending on the position within the oxyntic unit. Pre-oxyntic cells of the isthmus and neck represent the immature precursors. Though heterogeneous with respect to the degree of canalicular and tubulovesicular membrane development, they all contain secretory granules resembling those of either isthmus cells, immature surface mucous cells, neck cells or young chief cells. A secretory granule-free stem cell is not present in the bovine. Downward to the gland base genesis of canalicular as well as tubulovesicular membranes is gradually completed; thus pre-oxyntic cells give rise to mature oxyntic cells. Older degenerative oxyntic cells, primarily located within the gland bottom, are characterized by progressive involution of canalicular and tubulovesicular membranes. Towards the pit, differentiation of pre-oxyntic cells is associated with atypical and incomplete development of canaliculi and tubulovesicles. In consequence, these superficial oxyntic cells have a reduced secretory capacity from a morphological point of view.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 288 (1996), S. 91-97 
    ISSN: 1432-069X
    Keywords: Key words Hemidesmosomes ; Basement membrane ; Fetal skin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hemidesmosomes are junctional complexes involved in the attachment of epidermal basal keratinocytes to the basement membrane. To try to understand better the sequence of events in the morphogenesis of hemidesmosomes, we undertook an ultrastructural analysis of hemidesmosome formation in fetal and neonatal digit skin. Hemidesmosomes, defined as membrane-associated densities or plaques, were counted and scored for three morphological characteristics: (1) the presence of a sub-basal dense plate, (2) association with anchoring filaments within the lamina lucida and (3) contacts with intermediate filaments. No hemidesmosomes were evident at 7 weeks’ gestational age. Between 9 and 15 weeks the number of hemidesmosomes increased by about fourfold (from 20.6 ± 3.8 (SD) to 95.5 ± 8.4 per 40 μm of basal cell plasma membrane; P 〈 0.01). The association of hemidesmosomes with intermediate filaments and anchoring filaments also increased after 15 weeks ( P 〈 0.05). Early attachment plaques first appeared as triangular focal densities on the basal plasma membrane with the appearance of sub-basal dense plates, which later became both larger and more electron dense. By 15 weeks, an inner plaque could be distinguished from the outer plaque, which coincided with a closer association with intermediate filaments. Hemidesmosomes appeared fully developed by 15 weeks’ gestation. This study illustrates the structural relationship of hemidesmosomes to both intra- and extracellular filaments, suggesting close functional interactions. The complexity of the hemidesmosome plaque is also revealed early during development.
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  • 14
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Papillomatosis confluens et reticularis ; Minocyclin ; Tetracycline ; Elektronenmikroskopie ; Key words Confluent and reticulated papillomatosis ; Minocycline ; Tetracycline ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Confluent and reticulated papillomatosis (CRP) is a rare dermatosis of unknown aetiology. Recent electron microscopic studies suggest that CRP is a disorder of keratinisation. In our case we could not confirm the previously reported ultrastructural findings. CRP is generally resistant to therapy. We treated a 19-year-old patient with typical CRP with oral minocycline. Within a few weeks the eruption resolved completely. A mild relapse 7 months later responded promptly to a repeated course of minocycline. Twelve months after discontinuatin of therapy there is no evidence of recurrence. In CRP minocycline should be preferred to systemic retinoid therapy because of its minor side effects.
    Notes: Zusammenfassung Die Papillomatosis confluens et reticularis (PCR) ist eine seltene Erkrankung unklarer Ätiopathogenese. Neuere elektronenmikroskopische Untersuchungen stützen die Vermutung, daß eine Keratinisierungsstörung vorliegt. Anhand unseres Falles konnten wir diese Befunde allerdings nicht bestätigen. Die PCR ist ausgesprochen therapieresistent. Wir behandelten einen 19jährigen Patienten mit klinisch und histologisch typischer PCR systemisch mit Minocyclin. Innerhalb weniger Wochen heilten die Effloreszenzen vollständig ab. Ein 7 Monate später auftretendes leichtes Rezidiv konnte durch einen zweiten Behandlungszyklus schnell und erfolgreich behandelt werden. Der Patient ist jetzt bereits 12 Monate nach Absetzen der Therapie erscheinungsfrei. Zur Behandlung der PCR sollte Minocyclin wegen seiner geringeren Nebenwirkungen systemischen Retinoiden vorgezogen werden.
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  • 15
    ISSN: 1432-1106
    Keywords: GluR1 ; GABA ; Electron microscopy ; Cerebral neocortex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Specimens of human cerebral neocortex were obtained during neurosurgical operations and studied by immunocytochemistry and electron microscopy, using antibodies to the glutamate receptor subunit GluR1 and gamma-aminobutyric acid (GABA). Many GluR1-positive pyramidal neurons and fewer GluR1-positive nonpyramidal neurons were present in the cortex. Non-pyramidal neurons were more heavily labelled for GluR1 than pyramidal neurons. Most GABAergic neurons were labelled for GluR1. The white matter was unstained, except for occasional labelled neurons. This pattern of GluR1 immunostaining is similar to that in rat cerebral cortex, but is different from that in the hippocampus and amygdala, where large numbers of pyramidal or projection neurons, but few non-pyramidal or GABAergic neurons, were labelled for GluR1.
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  • 16
    ISSN: 1432-1106
    Keywords: Glutamate receptor ; Cerebral cortex ; White matter ; Electron microscopy ; Development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution of the [3H]alpha-amino-3-hydroxy-5-methylisoxzalepropionic acid (AMPA) receptor subunit GluR4 was studied in frontal, parietal and temporal cerebral cortex, subcortical white matter and corpus callosum of neonatal, immature and mature rats. In 1-to 2-day-old rats, a few oligodendrocyte progenitors and amoeboid microglia in the supraventricular part of the corpus callosum were immunolabelled for GluR4. At 7 to 10 days, the number of amoeboid microglia and oligodendrocyte progenitors in white matter increased; many neurons in cortex, including pyramidal neurons, were also moderately labelled for GluR4. The pattern of GluR4 immunostaining in 14-day-old rats was different from that in 7-to 10-day-old rats, but similar to the adult, in that there was no immunoreactivity in microglia and oligodendrocyte progenitors in subcortical white matter. A proportion of non-pyramidal neurons in cortex were moderately labelled, while some pyramidal neurons were lightly labelled. A population of small glial cells with features of oligodendrocyte progenitors were densely labelled in cortex.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 155 (1996), S. 561-567 
    ISSN: 1432-1076
    Keywords: Key words Glycogen deficiency ; Glycogen synthase ; Ketotic ; hypoglycaemia ; Corn (maize) ; starch ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three children from two German families are described and the observations compared with the previously published three families comprising eight patients. The two index cases presented with morning fatigue, had ketotic hypoglycaemia when fasting which rapidly disappeared after eating, and hepatic glycogen deficiency and absent or very low hepatic glycogen synthase activity. Metabolic profiles comprising glucose, lactate, alanine, and ketones in blood were typical for hepatic glycogen synthase deficiency. Symptoms were rapidly relieved and chemical signs corrected by introducing frequent protein-rich meals and night-time feedings of suspensions of uncooked corn (maize) starch. The discovery of oligosymptomatic and asymptomatic siblings suggests that there are more persons with undiagnosed hepatic glycogen synthase deficiency. Conclusion Liver glycogen synthase deficiency is likely to be more common than is believed today. It should be sought in children who, before the first meal of the day, present with drowsiness, lack of attention, pallor, uncoordinated eye movements, disorientation or convulsions and who have hypoglycaemia and acetone in urine.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 155 (1996), S. 561-567 
    ISSN: 1432-1076
    Keywords: Glycogen deficiency ; Glycogen synthase ; Ketotic hypoglycaemia ; Corn (maize) starch ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three children from two German families are described and the observations compared with the previously published three families comprising eight patients. The two index cases presented with morning fatigue, had ketotic hypoglycaemia when fasting which rapidly disappeared after eating, and hepatic glycogen deficiency and absent or very low hepatic glycogen synthase activity. Metabolic profiles comprising glucose, lactate, alanine, and ketones in blood were typical for hepatic glycogen synthase deficiency. Symptoms were rapidly relieved and chemical signs corrected by introducing frequent protein-rich meals and night-time feedings of suspensions of uncooked corn (maize) starch. The discovery of oligosymptomatic and asymptomatic siblings suggests that there are more persons with undiagnosed hepatic glycogen synthase deficiency.
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  • 19
    ISSN: 1432-1017
    Keywords: Key words Gallstone ; Cholesterol monohydrate crystals ; Phase separation ; Light scattering ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Phospholipid/cholesterol vesicles were solu-bilized by 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Above 30 mol% cholesterol (Ch) in the lipid vesicles several remarkable changes of the solubilization process were observed. (i) Two modes of solubilization: The effective detergent to lipid ratio Rc(M) for the formation of mixed micelles decreased from Rc(M) = 43 ± 3 at low lipid concentrations, [L]≤ 0.15 mm, to Rc(M) = 2.4 ± 0.3 above [L] = 0.5 mm (40 mol% Ch, T = 20 °C). (ii) At subsolubilizing CHAPS concentrations, filamentous and helical microstructures were formed, similar to those which were observed in native and model bile. (iii) The number of observed fibers was about two orders of magnitude higher in the presence of the negatively charged lipids phosphatidylglycerol (PG) and phosphatidic acid (PA) compared to the zwitterionic phosphatidylcholine (PC). Fiber formation began after 16–18 h using PG and PA compared to 3–4 days in the presence of PC. Screening of the charged lipids by NaCl effectively reduced the formation of fibers. Assuming binding of Na+ to the charged lipid aggregates, an intrinsic binding constant Kint = 0.6 M–1 was determined by applying the Gouy-Chapman theory. After the addition of CHAPS to PG/Ch vesicles, a fast initial solubilization of the vesicles (〈1 min) to mixed micelles (rh = 2.3 ± 0.2 nm) and small vesicles (rh = 23 ± 1 nm) was observed, followed by an intermediate period of 2 h, after which the formation of fibers occurred (〉15 h). The microstructures are visualized by darkfield and electron microscopy. The method of vesicle solubilization is compared to the dilution of concentrated micellar solutions, which is usually applied to model bile systems.
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  • 20
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    Biology and fertility of soils 21 (1996), S. 293-302 
    ISSN: 1432-0789
    Keywords: Key words Ammonium excretion ; Azorhizobium caulinodans ; Auxine ; 2 ; 4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Rice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings developed nodule-like tumors (para-nodules) along primary and secondary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Histologically, these tumors appeared as cancerous out-grown lateral-root primordes and were thus comparable with stem nodules of the legume Sesbania rostrata. Azorhizobium caulinodans (a diazotroph known as a specific endophyte of Sesbania rostrata) was introduced and became established inside rice para-nodules and in root tissues around tumor bases. The infection with A. caulinodans followed a typical “crack-entry” invasion at places where para-nodule tumors had emerged through the root cortex and epidermis. The bacteria settled with high cell densities in intercellular spaces of the induced tumors and betwen root cortical cells. Infection of plant cells took place both in the epidermis and in cortical tissue. Intracellularly established A. caulinodans was found inside the cytoplasm, surrounded by membrane-like structures. N2 fixation by tumor-inhabiting Azorhizobium sp. was increased at low O2 tensions (1.5–3 kPa) compared with an untreated control. Only a little activity remained at O2 tensions of 5 kPa and above. The present results confirm that root-tumor induction offers a suitable method of establishing diazotrophs endophytically in the roots of gramineous crops.
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  • 21
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    Biology and fertility of soils 21 (1996), S. 293-302 
    ISSN: 1432-0789
    Keywords: Ammonium excretion ; Azorhizobium caulinodans ; Auxine 2.4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Rice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings developed nodule-like tumors (para-nodules) along primary and secondary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Histologically, these tumors appeared as cancerous out-grown lateral-root primordes and were thus comparable with stem nodules of the legume Sesbania rostrata. Azorhizobium caulinodans (a diazotroph known as a specific endophyte of Sesbania rostrata) was introduced and became established inside rice para-nodules and in root tissues around tumor bases. The infection with A. caulinodans followed a typical “crack-entry” invasion at places where paranodule tumors had emerged through the root cortex and epidermis. The bacteria settled with high cell densities in intercellular spaces of the induced tumors and between root cortical cells. Infection of plant cells took place both in the epidermis and in cortical tissue. Intracellularly established A. caulinodans was found inside the cytoplasm, surrounded by membrane-like structures. N2 fixation by tumor-inhabiting Azorhizobium sp. was increased at low O2 tensions (1.5–3 kPa) compared with an untreated control. Only a little activity remained at O2 tensions of 5 kPa and above. The present results confirm that root-tumor induction offers a suitable method of establishing diazotrophs endophytically in the roots of gramineous crops.
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  • 22
    ISSN: 1432-1076
    Keywords: Key words Rhizomelic ; chondrodysplasia punctata ; Dihydroxyacetonephosphate-acyl-transferase ; Electron microscopy ; Peroxisomes ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rhizomelic chondrodysplasia punctata (RCDP) is clinically characterized by symmetrical shortening of the proximal limbs, contractures of joints, a characteristic dysmorphic face, and cataracts. In the classical form an impairment of several peroxisomal functions and enzymes (plasmalogen synthesis, phytanic acid oxidation, 3-oxoacyl-CoA thiolase) has been repeatedly shown. Recently a variant involving only the peroxisomal dihydroxyacetonephosphate acyltransferase (DHAP-AT) has been described. We present a patient with isolated DHAP-AT deficiency and all clinical, radiological, and pathological features of classical RCDP. For the first time, microscopy and immunocytochemistry of hepatocytes could be performed. Conclusion In contrast to studies on classical rhizomelic chondrodysplasia punctata which have shown enlarged peroxisomes in numbers varying from hepatocyte to hepatocyte, the peroxisomes in our patient seem to be normal in size, number and shape.
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  • 23
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    Archives of microbiology 166 (1996), S. 357-360 
    ISSN: 1432-072X
    Keywords: Key wordsEscherichia coli ; Capsule ; Serotype ; Edema disease ; Electron microscopy ; Cell adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of the cell surface of seven enterotoxemic Escherichia coli (ETEEC) O139:K12 strains isolated from piglets with edema disease were examined electron microscopically using both the negative-staining method and the freeze-substitution fixation method. Densely packed, fine fibers were observed; they consisted of a capsule layer approximately 25 nm thick around the cell surfaces of strains 107/86, IW-2, ED-3, ED-43, and ED-61, all of which have a capacity to adhere strongly to HEp-2 cells. In contrast, no such structure was observed on the surface of strains RK-O139 or ED-1, both of which adhere only weakly to HEp-2 cells. These results suggest that the capsule structure might be associated with the ability to adhere to HEp-2 cells and, as a result, also potentially play some role in ETEEC infection.
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  • 24
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    Bioscience reports 16 (1996), S. 159-187 
    ISSN: 1573-4935
    Keywords: Electron microscopy ; photosystem II ; thylakoid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract This review covers the recent progress in the elucidation of the structure of photosystem II (PSII). Because much of the structural information for this membrane protein complex has been revealed by electron microscopy (EM), the review will also consider the specific technical and interpretation problems that arise with EM where they are of particular relevance to the structural data. Most recent reviews of photosystem II structure have concentrated on molecular studies of the PSII genes and on the likely roles of the subunits that they encode or they were mainly concerned with the biophysical data and fast absorption spectroscopy largely relating to electron transfer in various purified PSII preparations. In this review, we will focus on the approaches to the three-dimensional architecture of the complex and the lipid bilayer in which it is located (the thylakoid membrane) with special emphasis placed upon electron microscopical studies of PSII-containing thylakoid membranes. There are a few reports of 3D crystals of PSII and of associated X-ray diffraction measurements and although little structural information has so far been obtained from such studies (because of the lack of 3D crystals of sufficient quality), the prospects for such studies are also assessed.
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  • 25
    ISSN: 1432-2307
    Keywords: Acinar cell carcinoma ; Fetal pancreas ; Electron microscopy ; Fibrillary inclusion ; Rough endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a case of pancreatic acinar cell carcinoma which contained a large number of pleomorphic inclusions with fibrillary internal structures and mature zymogen granules. To clarify the significance of fibrillary inclusions in the differentiation of acinar cells of the pancreas, we further investigated fetal pancreases (gestational weeks 16, 17, 19, 20 and 28). We found two types of inclusions: type A, corresponding to fibrillary inclusion of neoplastic acinar cells, was observed only in a 19-week fetus; type B showed a homogeneous density similar to that of zymogen granules. Type B was observed in all the fetuses after the 17th gestational week. Although the type A inclusion might be generated throught a different mechanism than the type B inclusion, the appearance of a large number of fibrillary inclusions in neoplastic acinar cells may represent a transient form of zymogen granule.
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  • 26
    ISSN: 1432-2307
    Keywords: Alveolar adenoma ; Lung neoplasms ; Flow cytometry ; Electron microscopy ; Proliferating cell nuclear antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alveolar adenoma of the lung is a poorly characterized, uncommon pulmonary lesion with proliferation of alveolar epithelium and septal mesenchyme. We describe the electron microscopy, immunohistochemistry and DNA flow cytometry in a case of alveolar adenoma in a 55-year-old woman. Alveolar adenoma appears to be a distinct benign neoplasm of the alveolar structures. Our findings further suggest that it is not a precursor of bronchioloalveolar carcinoma or other type II pneumocyte lesions of presumed malignant potential.
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  • 27
    ISSN: 1432-0878
    Keywords: Key words: Electrocyte ; Intermediate filaments ; Desmin ; Cytoskeleton ; Electron microscopy ; Electrophorus electricus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Desmin protein is an abundant constituent of the intermediate filaments in the electrocytes of the electric organ of the electric eel Electrophorus electricus. Polyclonal antibodies were raised against purified desmin from the electric organ and used for immunolabeling of the protein in reconstituted filaments. In thick sections of the main electric organ that has been stained with fluorescein-labeled desmin-specific antibodies, light microscope revealed a diffuse meshwork of desmin filaments dispersed in the cytoplasm of electrocytes. In the region under the membrane, the immunostaining was slightly more intense than elsewhere. The meshwork of intermediate filaments composed of desmin was examined by electron microscopy of the main electric organ. Immuno-gold labeling demonstrated a widespread meshwork of desmin filaments in the cytoplasm and in close association with the plasma membrane. These observations suggest that intermediate filaments play a role in the maintenance of the morphology of electrocytes and, as an intracellular meshwork spanning the width of the cell, they may contribute to the organization of the intracellular compartments.
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  • 28
    ISSN: 1432-0878
    Keywords: Key words: Innervation ; Heart ; Intracardiac neurone ; Nitric oxide ; Immunocytochemistry ; Electron microscopy ; Rat (Sprague Dawley) ; Guinea-pig (Dunkin Hartley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity of intracardiac neurones in the rat and guinea-pig was studied at the ultrastructural level. While some nitric oxide synthase-containing intracardiac neurones were very heavily labelled, with electron-dense immunoprecipitate distributed throughout the neuronal cell bodies and their processes, most of the labelled neurones exhibited a lighter and more patchy distribution of nitric oxide synthase-immunoreactive material. Synapses made by nitric oxide synthase-negative nerve fibres with labelled intracardiac neurones were seen. Conversely, many nitric oxide synthase-containing nerve fibres that made synaptic contacts with unlabelled intracardiac neurones were also observed. Some small granule-containing cells were nitric oxide synthase-immunoreactive and were associated with unlabelled nerve terminals, while non-immunoreactive small granule-containing cells that were innervated by nitric oxide synthase-immunoreactive nerves were also seen. Small patches of osmiophilic electron-dense material were observed in the cytoplasm of NADPH-diaphorase-positive intracardiac neurones. This is the first description of the ultrastructural distribution of nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in a subpopulation of intracardiac neurones of rat and guinea-pig heart and provides further evidence in support of a role for nitric oxide in the local control of the heart by intrinsic neurones.
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  • 29
    ISSN: 1432-0878
    Keywords: Key words: Ocellus ; Photoreceptor cells ; Retinal degeneration ; Subrhabdomeric cisternae ; Electron microscopy ; Immuno-electron microscopy ; Phosphatidylinositol transfer protein ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We studied the structure of ocellar photoreceptor cells of Drosophila melanogaster, particularly the subrhabdomeric cisternae which our previous studies have shown to be essential structures for turnover of photoreceptive membranes in compound eyes. Each ocellus contained elongated photoreceptor cells with rhabdomeres positioned distally. In the subrhabdomeric regions, endocytotic invaginations were frequently observed, suggesting active turnover of photoreceptive membranes. In the vicinity of the photoreceptive microvilli, membranous structures similar to the subrhabdomeric cisternae in compound eyes were observed. These membranous structures were immunopositive for the rdgB protein, a phosphatidylinositol transfer protein that is localized to the subrhabdomeric cisternae in compound eyes. The ocellar photoreceptor cells of the retinal degeneration mutants (rdgA,B) were also studied. In these mutants, retinal degeneration has been reported to start, in compound eyes, with the disappearance of the subrhabdomeric cisternae. We found that the ocellar subrhabdomeric cisternae also disappear during the initial stage of retinal degeneration. From these observations, we conclude that the mechanism of photoreceptive membrane turnover in ocellar photoreceptor cells involves the rdgB and probably the rdgA proteins which are associated with subrhabdomeric cisternae, as is the case for photoreceptive membrane turnover in compound eyes.
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  • 30
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    Cell & tissue research 284 (1996), S. 125-142 
    ISSN: 1432-0878
    Keywords: Key words: Chordotonal organ ; Scolopidium ; Mechanoreceptor ; Sensilla ; Electron microscopy ; Phylogenesis ; Teleogryllus commodus (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. More than 50 chordotonal sensilla, or scolopidia, embedded entirely in the integument were found in each side of the genital chamber wall in the female cricket, Teleogryllus commodus. Their cell bodies lie among the epidermal cells, and the tips of their dendrites terminate in the cuticle. About half of them contain two sensory cells (two-cell scolopidium), the others only one (one-cell scolopidium). The sensory cell in the one-cell scolopidium is the type-1 cell. In the two-cell scolopidium one is type-1 and the other type-2. Regardless of the number of sensory cells, they are all amphinematic. In the two-cell scolopidium only the type-2 dendrite, rich in microtubules, penetrates into the cuticle, bifurcates and terminates in the tube enclosed by an attachment cell; the type-1 never extends into the cuticle. On the other hand, the type-1 cell in the one-cell scolopidium projects its apex into the cuticle. The unique topography and structure of these scolopidia lead to the following hypothesis about the phylogenetic relationship between the scolopidia and other kinds of sensilla: the type-1 scolopidial sensory cell buried in the integument may be the original model, which through the loss of the long regular axoneme has given rise to type-2 cells. Modification of the apical region, the tubular body or ramification, may have lead to the cuticular sensilla corresponding to the development of the cuticular apparatus, and the scolopidia may have been withdrawn into the body cavity to form ordinary chordotonal organs.
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  • 31
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    Methods in cell science 18 (1996), S. 15-18 
    ISSN: 1573-0603
    Keywords: Angiogenesis ; Endothelial cells ; Angiogenesis analysis ; Electron microscopy ; Cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Determination of the structural characteristics of angiogenesis requires a procedure protective of the forming vascular fibers and the endothelial cell monolayer exhibiting cord formation. This report describes in situ fixation of angiogenic cultures in 96-well plates and the subsequent double embedding processing for electron microscopy. Cross sections of the monolayer are obtained without damage of the incipient capillaries.
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  • 32
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    European archives of oto-rhino-laryngology and head & neck 253 (1996), S. 205-213 
    ISSN: 1434-4726
    Keywords: Nasal neuropeptides ; Perennial rhinitis ; Mucosal glands ; Immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study morphological effects on the nasal and sinus mucosa, New Zealand White rabbits underwent either unselective, regional sectioning of sensory and parasympathetic nerve branches or topical treatment of the mucosa with capsaicin. Ten days after treatment, mucosal specimens were analyzed by light and electron microscopy. Immunohistochemistry was used to evaluate neuropeptides present, in particular substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y. In surgically denervated rabbits, mucosal glands were found to be enlarged and contained an increased number of zymogen granules having a bipartite substructure. Topical capsaicin application caused localized epithelial changes in the sinus mucosa and maxilloturbinal region of the nose, including clotting of cilia and an increased number of goblet cells. Reduced amounts of all neuropeptides investigated were found in the surgically denervated animals, while topical capsaicin treatment had only marginal effects on the mucosal neuropeptide content. The morphological changes observed after surgical denervation suggest an imbalance between neural stimulation and secretory capacity of the mucosal glands. These findings could explain the difference in clinical effect noted between sectioning of the vidian nerve and topical treatment with capsaicin in patients with perennial rhinitis.
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  • 33
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    Medical molecular morphology 29 (1996), S. 7-12 
    ISSN: 1860-1499
    Keywords: Keratin spherules ; Cholesterol crystals ; Epidermal cyst ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Numerous, small spherical inclusions with laminated horn-like material were observed in an epidermal cyst from the left earlobe of a 52-year-old Japanese man. They were examined by light and electron microscopy. Positive reactions obtained by staining with both oil red-O and anti-pankeratin antibody led to the conclusion that the inclusions consisted of lipid-rich keratin spherules. These were thought to have been formed in the hydrophobic regions of keratin proteins and non-polar lipids in the hydrophilic milieu of the cyst. Electron microscopy revealed cholesterol crystals within the spherules, suggesting that cholesterol had been slowly isolated from the lipoproteins and the membrane components of the cornified cells included in the lipid-rich keratin spherules, and had gradually become concentrated, finally appearing in the spherules as cholesterol crystals. With further study, a more detailed understanding of this process may throw some light on the development of gallstones and atheroembolism.
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  • 34
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    Medical molecular morphology 29 (1996), S. 37-42 
    ISSN: 1860-1499
    Keywords: Melkersson-Rosenthal syndrome ; Facial nerve sheath ; Electron microscopy ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To our knowledge, this is the first report of electron microscopic findings in the facial nerve sheath in Melkersson-Rosenthal syndrome. We performed decompression of the right facial nerve on a patient with Melkersson-Rosenthal syndrome. A part from the facial nerve sheath was obtained and observed with a transmission electron microscope. There were some fibers 180 to 200 nm in diameter which had obscure cross bandings, and also accumulations of these degenerated fibers among normal collagen fibers.
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  • 35
    ISSN: 1860-1499
    Keywords: Placental site trophoblastic tumor ; Intermediate trophoblast ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A rare placental site trophoblastic tumor (PSTT) in a 39-year-old female was studied. This tumor, protruding into the uterine cavity, was histologically similar to tumors in previously reported cases of PSTT. Ultrastructurally, the characteristic finding was the presence of perinuclear filaments. Also, the tumor cells were strongly positive for hPL by immunohistochemical method. These findings suggest that this was a tumor caused by neoplastic proliferation of the extravillous intermediate trophoblast.
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  • 36
    ISSN: 1860-1499
    Keywords: Long-spacing collagen ; Intramuscular nerves ; Neuromuscular diseases ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the incidence and morphological features of long-spacing collagen (LSC) in the intramuscular nerves of biopsied muscle tissues from patients with various neuromuscular diseases. LSC was found in 12 of 55 cases (21.8%). The muscles in all cases with LSC showed typical neurogenic changes at the light microscopic level. At the electron microscopic level, LSC was seen either in the vicinity of the basement membranes of the perineurium or Schwann cells, or running among the collagen fibrils. A close relationship between the form (compact or solitary type) and the periodicity of collagen was not confirmed.
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  • 37
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    Journal of High Resolution Chromatography 19 (1996), S. 111-116 
    ISSN: 0935-6304
    Keywords: Polynuclear aromatic hydrocarbons ; Liquid chromatography ; Alcohols ; Micelles ; Enviromental samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for the separation of polycyclic aromatic hydrocarbons (PAHs) by high-performance liquid chromatography using a hybrid micellar mobile phase is described. The detection of PAHs was carried out using the fluorescence method with programmable excitation and emission wavelength. The method is applied to the analysis of several environmental samples (sea water, sediments, limpets, sea worms) and several of these compounds are quantitated at concentration below 70 ng L-1(kg-1) in the original samples.
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  • 38
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    Journal of High Resolution Chromatography 19 (1996), S. 99-104 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Micellear electrokinetic chromatography ; Organic modifiers ; Naphthalene sulfonates ; Surface water ; Thermostatting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The production and use of naphthalene sulfonates can easily cause pollution of surface and other types of waters. In the present study, capillary electrophoresis in combination with UV absorption detection was used to separate 21 amino- and hydroxy-substituted naphthalene sulfonates which included multiple isomeric compounds. The influence of various parameters such as pH (which turned out to be extremely important), temperature of the surrounding air flow, and the use of buffer additives (micelles, cyclodextrins, organic modifiers) was studied. Complete separation of all analytes including the isomers, was achieved in two runs with a 50 mM boric acid/borate buffer, containing either 100 mM sodium dodecylsulfonate or 15% acetonitrile. The limits of detection obtained for the individual compounds typically were 20μgI-1. River water samples spiked at this concentration level could be analysed using a simple three-step sample clean-up procedure.
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  • 39
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    Journal of High Resolution Chromatography 19 (1996), S. 403-408 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Cryogenic trapping ; Capillary ; Focusing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cryogenic trapping of solutes leads to narrowing of the chromatographic band. By placing the trap at the end of a capillary column, it is possible to study the effectiveness of the trap in terms of producing a sharpened elution profile. The trap may be heated by supplementary heating, but here convective heating from the GC oven is employed simply by turning off the cryogenic coolant. It is estimated that it takes about 50 s for the trap to heat up sufficiently to allow trapped solute to be remobilized, although this depends upon the oven temperature and thermal mass of the trap. It can also be shown that the more volatile solutes mobilize faster from the trap in this particular mode of operation. The recovery of trapped components shows that there is essentially quantitative trapping, and the solutes are trapped just at the leading edge of the trap.
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  • 40
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    Journal of High Resolution Chromatography 19 (1996), S. 409-412 
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic chromatography ; Rhei Rhizoma ; Scutellariae Radix ; Coptidis Rhizoma ; Bioactive constituents determination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary electrophoretic method for simultaneous determination of six bioactive ingredients (berberine, palmatine, baicalin, sennoside B, emodin, and sennoside A) in the Chinse herbal formula San-huang-hsieh-hsin-tang was established. A carrier composed of aqueous buffer solution (50 mM sodium cholate, 15 mM sodium dihydrogen phosphate, and 4.25 mM sodium borate)-acetonitrile (3:2) was found to be the most suitable electrolyte for this separation. Contents of these constituents in a non-pretreated methanol-water extract of San-huang-hsieh-hsin-tang sample could be easily determined within 20 min. The effects of borate, cholate, and organic modifier (acetonitrile) concentration of the carrier on the migration behavior of the solutes were also studied.
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  • 41
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    Journal of High Resolution Chromatography 19 (1996), S. 418-418 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 42
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    Journal of High Resolution Chromatography 19 (1996), S. 485-491 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Qualitative analysis ; Quantitative analysis ; Retention indices ; Retention times ; Solvent effect ; Sulfur Chemiluminescence Detection (SCD) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatrography (GC) with sulfur chemiluminescence detection (SCD) is an outstanding combination for selectively determining trace concentrations of sulfur compounds in hydrocarbon samples. GC peaks can be identified by retention times when reproducible, automated injection techniques are used. However, as described in this work, analysts should be on the look out for retention shifting due to solvent effects from sample components. Three examples of retention shifting are presented: (1) thiophene by benzene; (2) methylthiophenes by toluene; and (3) dibenzothiophene by gas oil. Depending on samples and analysis conditions, retention shifts from a few hundredths to 1.5 min have been observed. Such retention shifts are likely to cause errors in peak identifications. Therefore, when using SCD, simultaneous FID monitoring is recommended as an aid in evaluating chromatograms for possible retention shifting due to solvent effects.
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  • 43
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    Journal of High Resolution Chromatography 19 (1996), S. 497-502 
    ISSN: 0935-6304
    Keywords: α-Monoacetotriacylglycerides ; Celastraceae ; Fatty acids ; GLC ; GLC-(NCI)MS ; Maytenus seed oils ; OV-225-OH, OH-terminated ; SOP-50, methoxy-terminated ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The seed oils of three Maytenus species have been examined by high temperature GLC using SOP-50 (methoxy-terminated) and OV-225-OH (OH-terminated) glasscapillary columns. The main compounds (71-76%) could be identified as α-mono-acetotriacylglycerols by a combination of high temperature GLC-MS in negative chemical ionization mode with a CH4/N2O mixture as reactant gas and other spectroscopical methods (infrared, 1H- and 13C-nuclear magnetic resonance spectroscopy). The OV-225-OH phase demonstrated better separation properties that the SOP-50 phase for this substance class and up to eight species of α-monoacetotriacylglycerols could be separated. The content of usual triacyclglycerols was below 1%. The results of the analysis of the individual fatty acids as their methyl esters by GC and GC-MS are also presented.
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  • 44
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    Journal of High Resolution Chromatography 19 (1996), S. 521-526 
    ISSN: 0935-6304
    Keywords: LSS model ; Whey proteins ; HIC of proteins ; Circular dichroism ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 45
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 527-529 
    ISSN: 0935-6304
    Keywords: High pressure gas chromatography ; Stationary phases ; Hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 46
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Enantiomeric separations ; Acidic compounds ; Neutral β-cyclodextrins ; Sulfobutyl ether β-cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution could be achieved for the enantiomers of acidic drugs, namely, sulindac, fenoprofen, ketoprofen, warfarin, and hexobarbital, in a buffer of pH 3 by the simultaneous addition of uncharged and charged β-cyclodextrin derivatives. The interaction of the analytes with the anionic sulfobutyl ether β-cyclodextrin provides the analytes with an adequate electrophoretic mobility whereas the interaction with various neutral β-cyclodextrins generates high enantioselectivity. Five neutral cyclodextrins, the native β-cyclodextrin, as well as methyl-, dimethyl-, trimethyl- and hydroxypropyl-β-cyclodextrin, were tested to enhance the enantioselectivity of the electrophoretic system. High resolution values and the shortest analysis times for the five drugs tested were achieved in a buffer made of 100 mM phosphoric acid adjusted to pH 3 with triethanolamine and containing dimethyl- or trimethyl-β-cyclodextrin in addition to sulfobutyl ether β-cyclodextrin.
    Additional Material: 5 Ill.
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  • 48
    ISSN: 0935-6304
    Keywords: Chlorobiphenyl congeners ; Aroclors ; DB-XLB phase ; HP-5/HT-5 serial coupled phases ; GC-ECD ; GC-MS-SIM ; GC-Ion Trap MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three HRGC systems (1: 30m DB-XLB capillary with MS-SIM detection; 2: 60m DB-XLB capillary with full-scan, ion-trap MS detection; and 3: Parallel dual-column DB-17 and series-coupled HP5/HT5 with ECD detection) were used to completely characterize multiple lots of 8 different-numbered Aroclor mixtures by quantitative calibration against 9 solutions containing primary standards of all 209 PCB congeners. Despite lower absolute sensitivity and more Aroclor congener coelutions than the dual-column ECD system, the MS systems enabled measurement of more congeners per Aroclor since their greater linear response range did not require dilution of samples and standards. Pairs of different lots of Aroclors 1248 and 1254 displayed markedly different proportions of congeners, and the 1254 pair displayed strong differences in the extent of ortho-chlorine substitution. The tables of congener weight percent distributions among Aroclors are more comprehensive and quantitatively precise than those of prior publications. However, the limitations of single-level calibration precluded measurement of all congeners to the ±10% accuracy desirable for establishing these Aroclors as secondary standards for comprehensive, quantitative congener-specific PCB analysis.
    Additional Material: 3 Ill.
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  • 49
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Mass spectrometry ; Electrospray ionization ; Fourier transform ion cyclotron ; Resonance ; Biomolecule analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the current state of the on-line combination of capillary electrophoresis (CE) electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS), and discuss aspects of the FTICR technique relevant to its use as a detection scheme for on-line separations. Aspects including sensitivity, mass resolution, duty cycle, and tandem mass spectrometric capabilities are discussed in the context of online separations with examples from the authors' laboratory.
    Additional Material: 6 Ill.
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  • 50
    ISSN: 0935-6304
    Keywords: HPLC of phenols ; Dianthus caryophyllus ; Carnation vascular wilt ; Fusarium oxysporum f. sp. dianthi ; Root phenolic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 51
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    Journal of High Resolution Chromatography 19 (1996), S. 43-48 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Mass spectrometry ; Wax esters ; Festuca arundinacea ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ester portion of epicuticular waxes of tall fescue (Festuca arundinacea Schreb.) is composed of mixtures of homologous series of fatty acids esterfied with fatty alcohols. GC analyses of natural esters gave rise to the separation of several compounds of different chain length. To identify and quantify individual components in the mixture, GC/MS analyses were carried out, and the mass spectra of each peak were recorded and analyzed for characteristic ions. This approach permitted a comparison with data obtained from classical methods using GC analysis of acid and alcohol moieties obtained by hydrolysis.
    Additional Material: 5 Ill.
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  • 52
    ISSN: 0935-6304
    Keywords: Optimization of GC conditions ; Sugar analysis ; Acid analysis ; Chlorogenic acid ; Raffinose ; Pectin decomposition products ; Galacturonic acid ; Arabinose ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Our GC-MS method for the simultaneous quantitation of sugars and acids as their silyl(oxime) derivatives, from one solution by one injection, has been extended to the reproducible determination of high molecular weight compounds sensitive to decomposition yet requiring a high evaporation temperature (e.g. chlorogenic acid and rffinose) and for the quantitation of the decomposition products of pectin (i.e., for the determination of galacturonic acid at low ng levels in the presence of a 10-100 fold excess of glucose eluting just before the acid). The optimized GC procedure has been used for quantitation of the sugar and acid (including chlorogenic acid) composition of potato samples, and for the determination of the increasing amount of the decomposition products of pectin substances in apple pulp after different storage times.
    Additional Material: 1 Ill.
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  • 53
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    Journal of High Resolution Chromatography 19 (1996), S. 66-66 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 54
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 55
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 180-182 
    ISSN: 0935-6304
    Keywords: trans-Fatty acids ; Semi-industrial frying ; Capillary GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 56
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 183-188 
    ISSN: 0935-6304
    Keywords: Chelating agents ; Complexation ; Capillary zone electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary electrophoretic method has been developed which achieves rapid quantitative separation and determination of ethylenediaminetetraacetic acid, N-(2-hydroxyethyl)ethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid, and nitrilotriacetic acid in Hanford tank waste simulant (TWS). Direct UV detection of Cu2+/chelator complexes is used to achieve enhanced sensitivity. The qualitative and quantitative reliability of the method and the quality of separations, as given by efficiency and resolution, is presented. In addition, the limits of detection and linearity of detector response with concentration are given for each chelator. The selection of Cu as the UV-absorbing species over other transition metals present in the waste is discussed.
    Additional Material: 5 Ill.
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  • 57
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    Journal of High Resolution Chromatography 19 (1996), S. 49-53 
    ISSN: 0935-6304
    Keywords: Polycyclic aromatic sulfur heterocycles ; Crude oil ; Oil maturity ; Fingerprinting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is presented for the identification and quantification of C2-substituted benzothiophenes in crude oil. The method will enable analysis of the pattern of these compounds, for example as a basis for differentiating crude oils from one another (fingerprinting) and for investigation of their suitability as indicators of oil maturity. Here results are reported for five crudes from Iraq, Venezuela, Saudi Arabia, the former Soviet Union, and the North Sea. The aromatic fraction of the crudes was oxidized and the dioxides of the heterocycles separated according to the number of carbon atoms in the side chains. The final separation was by capillary GC with atomic emission or flame ionization detection. A fluorinated analog was synthesized and used as internal standard. The concentrations of 2,3-, 2,4-, 2,7-, and 3,7-dimethylbenzothiophene ranged between 11 and 272 ppm. Three other dimethylated benzothiophenes present in lower amounts were also identified.
    Additional Material: 4 Ill.
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  • 58
    ISSN: 0935-6304
    Keywords: Capillary Supercritical Fluid Chromatography ; Mass Spectrometry ; SFC-MS ; On-line combination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An interface for coupling supercritical fluid chromatography to a magnetic sector mass spectrometer was developed and evaluated. The interface is based on direct introduction of the mobile phase, carbon dioxide, into the ion-source of the mass spectrometer. The SFC-MS system was optimized with respect to the signal-to-noise ratio. Under optimized conditions, the estimated detection limit for n-pentadecane is approximately 30 ppm. Spectra obtained in the electron-impact ionization mode show a very good similarity with library spectra. The performance of the SFC-MS system was evaluated by the analysis of a number of test mixtures. A sample containing several low molecular mass, thermally unstable compounds, which could neither be analyzed by GC-MS nor by LC-MS, was analyzed. Also for the analysis of high molecular mass compounds, the coupled system showed a good performance.
    Additional Material: 9 Ill.
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  • 59
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    Journal of High Resolution Chromatography 19 (1996), S. 37-42 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The headspace gas in static headspace gas chromatography contains mostly saturated water vapor. In the case of the cryofocusing enrichment technique this may cause baseline distortion in the early part of the chromatogram or may even lead to ice-plugging of the capillary column. A water-trap is described in which the water vapor is removed from the headspace gas before entering the cryo-trap. The water trap is packed with lithium chloride on a porous support and is regenerated after each analysis by heating under backflush conditions. It therefore can be used for automatic operation. Data are given for the precision and accuracy, and some practical examples, for environmental and flavor analysis are shown.
    Additional Material: 6 Ill.
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  • 60
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    Journal of High Resolution Chromatography 19 (1996), S. 59-61 
    ISSN: 0935-6304
    Keywords: Steam chromatography ; Salt-water stationary phases ; Retention of alcohols ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 61
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Ion-Trap Mass Spectrometry ; Pesticide residue analysis ; Eggs ; Ardea cinera ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 62
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    Journal of High Resolution Chromatography 19 (1996), S. 65-65 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 63
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    Journal of High Resolution Chromatography 19 (1996), S. iii 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
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    Journal of High Resolution Chromatography 19 (1996), S. 80-84 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Specific detectors ; ECD/FPD response ratios ; Retention indices ; Identification on real samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A previous paper reported the possibility of using the ratio between the responses of two different specific detectors to a single compound (detector response ratio, DRR) as an identification criterion for that compound, in combination with its retention index.This article gives some applications of DRR in the identification of some pesticides in four different fruits (apples, apricots, strawberries, and peaches) in a range varying from 0.02 to 1.3 ppm, by means of their ECD/FPD DRRs. After clean-up GC analyses were performed on a single column with dual parallel detection; a personal computer system was used for data analysis.
    Additional Material: 4 Ill.
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  • 65
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    Journal of High Resolution Chromatography 19 (1996), S. 91-94 
    ISSN: 0935-6304
    Keywords: Chiral selector anchored to polysiloxane ; Chiral phase capillary GC ; Immobilization ; Thermal treatment ; High enantioselectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral selector L-t-leucine-t-butylamide has been anchored to a polysiloxane by nucleophilic displacement of 2,2,2-trifluoroethyl ester-functionalized block polysiloxanes with L-t-leucine-t-butylamide. Attempts were made to immobilize the chiral polysiloxanes inside the capillaries by thermal treatment at 300°C for 30-90 min. The polysiloxanes were found to be more resistant than Chirasil-Val to the racemization caused by such high temperature treatment. Capillary columns coated with this type of immobilized polysiloxane have shown very high enantioselectivity and thermal stability.
    Additional Material: 3 Ill.
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  • 66
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    Journal of High Resolution Chromatography 19 (1996), S. 284-284 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 67
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    Journal of High Resolution Chromatography 19 (1996), S. 277-283 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Coupled columns ; Four factor optimization ; Simplex method ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optimization of a gas chromatographic system with two capillary columns coupled in series in a single oven for the linear temperature programmed separation of a mixture of C1—C10 hydrocarbons has been carried out using the simplex optimization method. The following four selectivity parameters were optimized: the initial temperature of the oven; the initial hold time; the temperature programmed rate; and the pressure at the mid-point of the system. The optimization procedure was monitored by the Cp criterion.
    Additional Material: 3 Ill.
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  • 68
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis-mass spectrometry ; Membrane preconcentration ; Capillary electrophoresis ; Sulfonated membrane ; Polar drug metabolites ; Toxic oil syndrome ; Eosinophilia-myalgia syndrome ; 3-Phenylamino-1,2-propanediol ; 3-Phenylamino-L-alanine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 69
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    Journal of High Resolution Chromatography 19 (1996), S. VII 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 70
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    Journal of High Resolution Chromatography 19 (1996), S. 298-300 
    ISSN: 0935-6304
    Keywords: Dynamic head space ; Coffee berry ; Identification ; Hypothenemus hampei ; Plant-insect relationship ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 71
    ISSN: 0935-6304
    Keywords: Capillary GC ; Drug screening ; Retention index ; Reporting ; Mean list length ; Blood analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dual-column gas chromatographic retention index method was evaluated for the toxicological screening for basic drugs in autopsy blood samples. The dual-column approach with DB-5 and DB-1701 capillary columns doubles the Identification Power of the corresponding single column methods. The long-term intralaboratory variation of the dialkylfluoroaniline series based retention indices of drugs in blood ranged from 0.03% to 0.2% which was generally better than that obtained using the relative retention time. Novel software is described for the processing and reporting of the dual-column chromatographic data in analytically useful form. Besides retention data, the response factors served as an additional identification factor.
    Additional Material: 4 Ill.
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  • 72
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    Journal of High Resolution Chromatography 19 (1996), S. 327-332 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Separation performance ; Fourier analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple procedure is presented for determining separation performance of HRGC analysis of multicomponent mixtures. The procedure is based on the computation of Autocovariance Function (EACVF) from the digitized experimental chromatogram. Graphic inspection of the EACVF plot permits easy computation of the width value of the single component peak, σ; from the EACVF value at t=O the number of component in the mixture, m, can be simply derived. From these two basic quantities all the other chromatographic performance attributes can be calculated. The consistency of the procedure is tested for different chromatograms and compared with the more complex EACVF fitting method. Several features of the multicomponent chromatogram, overloading effects included, are directly detected.
    Additional Material: 4 Ill.
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  • 73
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    Journal of High Resolution Chromatography 19 (1996), S. 339-344 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Trace gas analysis ; Multichannel thick film silicone rubber traps ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Established standard methods for analyzing semi-volatile pollutants by capillary gas chromatography are cumbersome, time-consuming, and expensive. With the longer term aim of replacing the sample preparation procedures with convenient concertrating and thermal desorption steps, thick film silicone rubber traps were constructed in a novel multi-channel configuration. Tests were performed to determine breakthrough volumes and thermal desorption characteristics for total transfer of the trap contents to a capillary column. Initial results are very promising.
    Additional Material: 6 Ill.
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  • 74
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    Journal of High Resolution Chromatography 19 (1996), S. 333-338 
    ISSN: 0935-6304
    Keywords: Adsorptive enrichment/thermal desorption ; Microtrap ; VOC and PVOC analysis ; Humid air sample analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An instrument has been developed and tested for the continuous measurement of volatile organic compounds (VOC) in air. The system consists of a gas chromatograph equipped with a dedicated sampling device that allows the sample to be transferred to a cooled microtrap via sampling loops (10, 100, 250 ml) or via a direct pump transfer to the trap. The microtrap is placed in the chromatographic oven just below a modified split-splitless injector, allowing direct liquid injection for calibration of the system; the injector is in communication with the sampling valve equipped with the loop and the sampling pump. The system allows 24-hour sampling and analysis of a large number of VOC (up to 25 individual hydrocarbons ranging from C2—C9) and also polar volatile organic compounds PVOC. Thanks to the particular trap geometry, a minimum consumption of liquid nitrogen (between 150—300 ml) is needed for each analytical run and no water managing system is normally required for humid air samples.
    Additional Material: 5 Ill.
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  • 75
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    Journal of High Resolution Chromatography 19 (1996), S. 353-358 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Gas chromatography-mass spectrometry ; Essential oil analysis ; Ylang-ylang oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steam distillation (SD), simultaneous distillation-solvent extraction (SDE), and supercritical (CO2) extraction (SFE) were used to isolate volatile secondary metabolites from fresh, totally mature flowers of Colombian ylang-ylang (Cananga odorata). The various extracts were analyzed by capillary chromatography (DB-1, DBWAX, 60 m columns) using FID, NPD or MSD (EI, 70 eV). Kováts indexes, mass spectra, or standard substances were employed for compound identification. 51, 70, and 73 compounds at concentrations above 100 ppb were detected in the SD, SDE, and SFE extracts, respectively. The main constituents of these extracts were linalool (20.7, 28.0, and 16.5%), germacrene-D (10.1, 3.1, and 20.3%) benzyl benzoate (14.1, 2.9, and 3.9%), benzyl acetate (9.6, 17.0, and 6.2%), caryophyllene (3.1, 2.9, and 3.9%), and p-methylanisole (6.8, 6.1, and 2.7%). 85% of the composition of SDE extracts was represented by oxygenated compounds. Heavy hydrocarbons (Cn 〉20) and fatty acids were found only in the SFE extracts, which also had a higher content of nitrogenated compounds (phenylacetonitrile, 4-methylbenzaldoxime, indole, 2-phenyl-nitroethane, and methyl anthranilate) and sesquiterpenes (43% vs 19.5% in SD and 8.1% in SDE) and 1.5 - 2 times lower concentration of monoterpenes and light oxygenated compounds than the SD (49.7%) and SDE (64.5%) extracts.
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  • 76
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    Journal of High Resolution Chromatography 19 (1996), S. 359-361 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Atomic emission detection ; Triclosan ; Dental plaque ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A validated gas chromatographic method for the determination of triclosan in human dental plaque is described. Based on plaque sample weights of 10 mg, the limit of detection (2 × S/N) is 0.5 μg/g. The method is linear (r = 0.9986) from the limit of detection to 50 μg/g. Recoveries from placebos spiked with 2.0, 25, and 50 μg/g of triclosan were 105.6%±7.5%, 107.2%±3.1%, and 99.1%±1.1%, respectively (n = 3 at each level). Twenty replicate preparations and analyses of a homogenized sample, conducted by two operators over the course of 4 days, showed agreement to within 9% RSD. Analyses of dental plaque collected from patients after brushing with dental cream containing triclosan, shows triclosan to be retained in dental plaque at concentrations above the minimum inhibitory concentration (1 μg/g) after 12 h.
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  • 77
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    Journal of High Resolution Chromatography 19 (1996) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 78
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    Journal of High Resolution Chromatography 19 (1996), S. 371-371 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 79
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    Journal of High Resolution Chromatography 19 (1996), S. 377-382 
    ISSN: 0935-6304
    Keywords: Capillary chromatography ; Boiling points prediction ; Identification ; Chlorobenzenes ; Phenols ; Programmed temperature ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantitative correlations between physicochemical parameters and structure of various solutes and their gas chromatographic behavior were investigated in order to predict the retention values. The identification of unknown samples in gas chromatographic routine analysis of environmental samples is enhanced by the use of these correlations in conjuction with other chromatographic methods and with mass spectrometry. The boiling points of many compounds are easily found in literature and therefore their correlation with retention values obtained in isothermal or programmed temperature analysis permit restriction of the choice of names of unknown compound to within a narrow range. The correlation between the boiling points and the retention times of chloro- and bromo-benzenes and of some chloro- and nitro- substituted phenols was investigated on non-polar capillary columns and permitted the tentative identification of many compounds belonging to these homologous series.
    Additional Material: 3 Ill.
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  • 80
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; FID, O-FID, and MS detection ; Glycol ethers and glycol ether acetates ; Heptafluorobutyryl derivatives ; Mass spectra ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twelve compounds, commonly used as industrial solvents and belonging to the chemical class of glycol ethers and glycol ether acetates, were investigated. Several analytical conditions, applied to single or connected capillary columns of different length and polarity coating and connected to FID, O-FID and MS detection systems, were assayed. Tests on heptafluorobutyryl derivatives were also attempted to improve the analytical sensitivity. The aims were to establish gas chromatographic methods suitable for analysis of reference standard compounds and to verify their applicability to biological matrix analysis for pharmacokinetic and toxicological studies, since these chemicals have been shown to be hazardous in laboratory animals and are presumed to be dangerous in man.
    Additional Material: 6 Ill.
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  • 81
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 444-448 
    ISSN: 0935-6304
    Keywords: LC-GC coupling ; Loop-type interface ; Alcohols ; Sterols ; Olive oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified loop-type interface is decribed which uses two 6-way valves and concurrent eluent evaporation to perform an on-line transfer and simultaneous gas chromatographic analysis of two different fractions pre-separated by liquid chromatography. The interface is used to simultaneously analyze aliphatic alcohols and sterols present in olive oil. LC pre-separation is carried out using a normal phase column (20 cm × 0.21 cm i.d.) and hexane-isopropanol (99:1) as a mobile phase at a flow of 0.2 ml/min; for the GC analysis a 5 % phenyl, 95 % dimethyl siloxane (25 m × 0.32 mm i.d., 0.4 μm film thickness) column is used.
    Additional Material: 4 Ill.
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  • 82
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 462-462 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 83
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 463-463 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 84
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 449-456 
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography (SFC) ; Packed columns ; Pressure drop ; Selectivity ; Resolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of pressure drop on retention, selectivity, plate height and resolution was investigated systematically in packed supercritical fluid chromatography (SFC) using pure carbon dioxide as the mobile phase. Numerical methods developed previously which enabled the prediction of pressure gradients, diffusivities, capacity factors, plate heights and resolutions along the length of the column were used for the model calculations. The effects of inlet pressure and supercritical fluid flow rate on selectivity and resolution are studied. In packed column SFC with pure carbon dioxide as the mobile phase, the pressure drop can have a significant effect on resolution. The flow rate is shown to have a larger effect than generally realized. The calculated data are shown to be in good agreement with the experimental results. Finally, the variation of the chromatographic parameters along a 5.5 meter long model SFC column is illustrated. The possibilities and limitations of using long packed columns in SFC are discussed. It is demonstrated that long columns with large plate numbers do not necessarily yield better separations.
    Additional Material: 7 Ill.
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  • 85
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 464-464 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 86
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Purge and trap extraction ; 1,2,4-TCB ; Environmental analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution gas chromatography (HRGC) coupled to a “purge and trap” extraction-injection technique is described as a method of determining 1,2,4-trichlorobenzene in water at levels as low as parts-per-trillion (ppt). In order to investigate the interference from other volatile organic compounds (VOCs) several detection systems were compared: flame ionization, electron capture, and mass spectrometry-multiple ion detection. Concentrations ranging from 15 to 600 ng/L were analyzed in 20 ml standard aqueous solutions. The mean accuracy of the method varied from 89 to 103%, and its mean precision varied from ± 0.85 to ± 7.5 % for all detectors. The detection limits were 20 ng/L for FID, 2 ng/L for ECD and 0.5 ng/L for MID-MS detectors. The procedure was successfully applied to the analysis of industrial waste waters. The necessity of an appropriate internal standard to improve the quantitative determination and to determine possible losses or degradation of 1,2,4-trichlorobenzene during handling or storage is discussed.
    Additional Material: 5 Ill.
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  • 87
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 469-471 
    ISSN: 0935-6304
    Keywords: Microextration ; GC/MS ; Chlorobenzenes ; Water samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 88
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 465-469 
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction (SFE) ; Beef ; Anabolic steroids, synthetic ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 89
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. vii 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 478-480 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Chiral separation ; Cyclodextrins ; Methoxamine ; Lobeline ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 91
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 492-496 
    ISSN: 0935-6304
    Keywords: High - speed capillary GC ; Carbon dioxide cryotrap ; Deactivated metal tubing ; Thermal decomposition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ten different metal tubings were investigated for thermal decomposition of analytes when used as the trap tube in a cryotrap/thermodesorption inlet system. No noticeable sample decomposition of hydrocarbons, chlorinated hydrocarbons and a brominated hydrocarbon was observed for six of the tubings with hydrogen as the carrier gas. This observation may be partly attributed to the developed deactivation techniques that produce inert metal tubings that are being widely adopted by many column manufacturers, the different trap materials used in comparison to previous studies and the decreased sample residence time in the hot trap tube. A cryotrap using carbon dioxide was constructed and tested as a alternative to the previously used liquid nitrogen based systems. This cryotrap was able to trap compounds with a boiling point of 80°C.
    Additional Material: 5 Ill.
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 511-514 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Enantiomer separation ; Amino acids ; N-Alkyloxycarbonyl alkylamide derivatives ; Nucleophilic substitution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of amino acids were first converted into N-alkyloxycarbonyl 2,2,2-trifluoroethyl esters, and then into N-alkyloxycarbonyl alkylamides by nucleophilic substitution of the ester group with amines. The first reaction proceeds instantaneously, while the second substitution occurs smoothly with n-propylamine and isobutylamine. The final derivatives were produced for separation on a capillary column coated with Chirasil-Val by GC. Pro, which is difficult to separate completely as its N-perfluoroacyl alkyl ester derivative, showed complete separation of the enantiomeric pair. All amino acids examined in this study showed an increased separation factor.
    Additional Material: 3 Ill.
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 530-533 
    ISSN: 0935-6304
    Keywords: High-performance liquid chromatography ; Paeoniae Radix ; Peony constituent separation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 543-548 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; High temperature ; Dead time ; Constants of the n-alkane retention time curve ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In gas liquid chromatography, the column dead time and the constants of the n-alkane retention time curve are calculated by the multiparametric least-squares regression iterative method at high temperature between 180 and 270°C. The method was applied to two types of columns. The first group includes eight packed columns (seven OV polymethylphenylsiloxane and Apolane-87), while the second includes five glass capillary columns (four methylsilicone with different film thicknesses and Apolane-87). The calculated tM and b values were compared with those obtained by Guardino's, Grobler's, and Kaiser's methods. The influences of coating thickness and temperature thereon were investigated.
    Additional Material: 4 Tab.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 569-570 
    ISSN: 0935-6304
    Keywords: Microbore SFC ; Chiral separation ; 3,5-Dimethylphenyl carbamate derivative of cellulose ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 559-563 
    ISSN: 0935-6304
    Keywords: Pesticide residue analysis ; Solid phase extraction ; Ground water ; Surface water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A critical study of a solid phase extraction method using C18 SPE columns for the determination of 23 halogenated pesticides is presented. Type of sorbent, sorbent mass, flow rate in the extraction process, sample concentration of the different compounds, sample volume, pH, ionic strength and type of water were evaluated. Recoveries of pesticides under study yield a linear relationship, except for conazole fungicides and captan. Losses can be expected for heptachlor, aldrin, and captan. Sample volume and flow rate of extraction affect recoveries. Matrix effects from surface and groundwaters were observed. Recoveries for vinelozolin and dieldrin from groundwater were lower than those obtained from nanopure water. In river water losses of these compounds are higher. Captan and penconazole were not present and high losses were obtained for trifluralin, α-BHC, γ-BHC, tri-allate and chlorpyriphos. Impurities arising from the sorbent materials of cartridges have been detected.
    Additional Material: 6 Tab.
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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 549-558 
    ISSN: 0935-6304
    Keywords: Size exclusion chromatography ; Petroleum waxes ; Flame ionization detector ; Refractive index detector ; Molecular weight distribution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular weight distribution of solid petroleum waxes is a key parameter for the general characterization of these materials. Particular interest concerns extremely large components, typically present in oil distillation residua, and solid deposits found in oil production facilities. Molecular weight distributions of oil waxes were determined in this work by high temperature size exclusion chromatography. Separations were carried out with two different eluents, namely toluene and ortho-dichlorobenzene and two detection systems, these being a differential refractive index and a flame ionization detector. Toluene proved to be the best choice when combined with flame ionization detection. Better uniformity of response was the greatest advantage achieved by this approach. The experimental set up permitted analysis of samples containing molecules with up to 138 carbon atoms. Burning properties of very large molecules, isomerism affecting calibration, and signal asymmetry when flame ionization detection was adopted were three issues still requiring additional efforts to understand and to improve analysis accuracy.
    Additional Material: 7 Ill.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 577-580 
    ISSN: 0935-6304
    Keywords: Phenolic compounds ; Solid phase extraction ; Coal gasification ; GC/MS ; XAD-4 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 588-590 
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction ; Water samples ; Polycyclic aromatic hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 585-587 
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Volatiles ; 2-Heptanol ; Ethyl benzoate ; (E)-Hex-2-enal ; 1-Terpinen-4-oI ; Rubus glaucus ; Rosaceae ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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