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  • 2000-2004  (536)
  • 1890-1899  (2.322)
  • General Chemistry  (2.700)
  • Magnetic resonance imaging  (158)
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  • 101
    ISSN: 1432-1920
    Schlagwort(e): Key words Hemimegalencephaly ; Positron emission tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report hemimegalencephaly in a 44-year-old woman with mental retardation, epilepsy and a mild hemiparesis. In addition to typical findings on MRI, 2-deoxy-2[18F]fluorodeoxyglucose positron-emission tomography (PET) demonstrated glucose hypometabolism of the affected hemisphere. The results of PET have been coregistered with morphological information from the MRI studies by image fusion.
    Materialart: Digitale Medien
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  • 102
    ISSN: 1432-1920
    Schlagwort(e): Key words Cerebral palsy ; Birth asphyxia ; Magnetic resonance imaging ; Single-photon emission computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe the findings on single-photon emission computed tomography (SPECT) in patients with perinatal asphyxia at term, with perirolandic cortico-subcortical changes on MRI, and to correlate them with clinical features. SPECT of 7 patients was obtained after injection of 185–370 MBq of Tc-99m-ECD (ethyl cysteinate dimer). The patients had spastic quadriplegia (7/7) with perinatal asphyxia (6/7) at term (7/7). The results were correlated with the MRI findings. Hypoperfusion of the perirolandic cortex was clearly seen on SPECT in all patients, even in two with subtle changes on MRI. SPECT demonstrated a more extensive area of involvement than MRI, notably in the cerebellum (in 4), the thalamus (in 7) and basal ganglia (in 5), where MRI failed to show any abnormalities.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 917-922 
    ISSN: 1432-1920
    Schlagwort(e): Key words Mouth, cysts ; Neck, cysts ; Glands, salivary ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We reviewed the MRI of 20 patients with a ranula (8 simple and 12 plunging) and ten with other cystic masses in the floor of the mouth and/ or suprahyoid portion of the neck (three haemangiomas, two neuromas, one monomorphic adenoma, one lipoma, two lateral cervical cysts and one dermoid cyst). Histological diagnoses were obtained in all cases with the exception of one presumed haemangioma. Ranulas were all well-defined, homogeneous masses giving low signal on T1-and markedly high signal on T2-weighted images. While simple ranulas were all confined to the sublingual space, plunging ranulas were centered on the submandibular space and tended to spill into one or more adjacent spaces. They extended into the sublingual space anteriorly (producung a so-called tail sign) in eight of 12 cases and into the parapharyngeal space superiorly in five. Although they sometimes filled a considerable part of the parapharyngeal space, displacement of surrounding muscles or vessels was usually slight, which was thought to reflect the nature of extravasation pseudocysts. All other cystic masses in our study had one or more MRI finding different from those of ranulas and could be easily differentiated from them.
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 112-114 
    ISSN: 1432-1920
    Schlagwort(e): Key words Hypophosphataemia ; Brain ; Myelinolysis, extrapontine ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report a 38-year-old woman with extreme hypophosphataemia in whom CT and MRI disclosed bilateral lesions within the basal ganglia, thalamus and occipital lobes. After adequate substitution of phosphate the lesions grossly resolved and the patient recovered. This case is the first to demonstrate that profound changes of serum phosphate may be associated with reversible brain lesions.
    Materialart: Digitale Medien
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  • 105
    ISSN: 1432-1920
    Schlagwort(e): Key words Carcinoma nasopharyngeal ; Radionecrosis ; Magnetic resonance imaging ; Pulse sequences
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We examined nine patients with histologically proven nasopharyngeal carcinoma (NPC), treated with radiotherapy, using dynamic susceptibility contrast MRI (DSC-MRI). In eight there was clinical evidence of radionecrosis of the temporal lobe, and one was examined for local recurrence in the nasopharynx. All patients had either high-signal finger-like or cystic lesions in the temporal lobes on T2-weighted images. Heterogeneous contrast enhancement occurred in all patients. Relative regional cerebral blood volume (rrCBV) mapping revealed marked hypoperfusion in all patients. One underwent bilateral temporal lobectomy and radionecrosis was confirmed histologically.
    Materialart: Digitale Medien
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  • 106
    ISSN: 1432-1920
    Schlagwort(e): Key words Dysplasia, focal cortical ; Hamartomas ; Epilepsy ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Focal cortical dysplasia (FCD) is a pathological entity first described in 1971. Other more subtle cortical malformations found in patients with epilepsy include microdysgenesis (MD), and glioneuronal hamartias. Although these glial and neuronoglial malformations have distinct histological features, there is terminological confusion in the radiological literature. Few cases have been reported in adults with both imaging and histology. We address these issues, giving a radiological-pathological correlation of histologically proven cortical malformations in adults. We describe clinical, radiological and histological features of 12 cases (five FCD, five MD with glioneuronal hamartias, and two hamartomas), unassociated with other conditions, and discuss them in the light of the literature. FCD is usually seen on MRI as cortical thickening, with or without signal change, which may extend into the adjacent white matter. On histology, abnormal neurons and/or glial cells, blurring of the grey-white matter interface, myelin pallor, demyelination, and gliosis may be found. Glioneuronal hamartias and hamartomas usually appear as complex masses on MRI. FCD and hamartias may be associated, and a combination of imaging findings may be seen on MRI. Atrophy of the ipsilateral hippocampus may be present on MRI in patients with hamartias, and minor cell loss on histology, but not definitive hippocampal sclerosis. Although the imaging findings of cortical malformations are protean, some characteristic MRI features, with histological correlates, may be found. The relevance of most of these observations remains unclear.
    Materialart: Digitale Medien
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  • 107
    ISSN: 1432-1920
    Schlagwort(e): Key words Acquired immunodeficiency syndrome ; Magnetic resonance imaging ; Contrast-enhancement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Our purpose was to determine whether triple-dose delayed contrast-enhanced images would improve lesion detection in patients with symptomatic human immunodeficiency virus (HIV) infection. We reviewed 33 MRI studies on 29 patients. Single-dose immediate T 1-weighted spin-echo (1x-T 1) images were compared with delayed triple-dose images (D3x-T 1). Two neuroradiologists decided which technique showed more lesions, increased lesion conspicuity and/or altered the radiologic diagnosis. The D3x-T 1 technique improved lesion detection in 14 of 29 patients (48 %). In two patients (7 %), the improvement changed the radiologic diagnosis by showing new meningeal lesions.
    Materialart: Digitale Medien
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  • 108
    ISSN: 1432-1920
    Schlagwort(e): Key words Cerebral autosomal dominant arteriopathy ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Clinical data and MRI findings are presented on 18 subjects from two families with neuropathologically confirmed CADASIL. DNA analysis revealed mutations in exon 4 of Notch 3 gene in both families. All family members with mutations in Notch 3 gene had extensive abnormalities on MRI, principally lesions in the white matter of the frontal lobes and in the external capsules. Of several family members in whom a diagnosis of CADASIL was suspected on the basis of minor symptoms, one had MRI changes consistent with CADASIL; none of these cases carried a mutation in the Notch 3 gene. MRI and clinical features that may alert the radiologist to the diagnosis of CADASIL are reviewed. However, a wide differential diagnosis exists for the MRI appearances of CADASIL, including multiple sclerosis and small-vessel disease secondary to hypertension. The definitive diagnosis cannot be made on MRI alone and requires additional evidence, where available, from a positive family history and by screening DNA for mutations of Notch 3 gene.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 272-274 
    ISSN: 1432-1920
    Schlagwort(e): Key words Rhombencephalosynapsis ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rhombencephalosynapsis is an unusual disorder characterised by maldevelopment of the rhombencephalon, sometimes with supratentorial midline anomalies. We report MRI findings in a 39-year-old woman, the oldest in the literature. MRI demonstrated hypoplasia of the cerebellar vermis, with fusion of the cerebellar hemispheres and abnormally oriented folia. Supratentorial anomalies were also seen.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 360-362 
    ISSN: 1432-1920
    Schlagwort(e): Key words Cyst, cavum septi pellucidi ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A 20-year-old woman with secondary amenorrhoea and an empty sella turcica was found to have a cyst of the cavum septi pellucidi (CSP) on MRI. The cyst had regressed spontaneously on follow-up MRI.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 406-412 
    ISSN: 1432-1920
    Schlagwort(e): Key words Lymphoma, primary central nervous system ; Chemotherapy ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract On MRI, primary brain tumors are commonly seen as contrast-enhancing masses surrounded by areas of abnormal signal on T2-weighted images. Following successful treatment tumors may no longer show contrast enhancement. The residual abnormalities are assumed to be represent “edema” and infiltrating tumor cells. We report nine patients with primary lymphoma of the central nervous system who had complete responses to intravenous methotrexate, but did not receive intrathecal chemotherapy or cranial irradiation. After complete resolution of contrast-enhancing lesions, persistent abnormalities on T2-weighted images in the region of prior tumor were initially assumed to reflect residual viable tumor. As they remained unchanged for years, however, this may not hold true in the cases in which primary central nervous system lymphoma responds to chemotherapy alone.
    Materialart: Digitale Medien
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  • 112
    ISSN: 1432-1920
    Schlagwort(e): Key words Corpus callosum ; White matter lesions ; Cerebral ischaemia ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Many studies of white matter high signal (WMHS) on T2-weighted MRI have disclosed that it is related to cerebral ischaemia and to brain atrophy. Atrophy of the corpus callosum (CC) has also been studied in relation to ischaemia. Our objective was to test the hypothesis that CC atrophy could be due to ischaemia. We therefore assessed CC, WMHS and brain atrophy in patients with risk factors without strokes (the risk factor group) and in those with infarcts (the infarct group), to investigate the relationships between these factors. We studied 30 patients in the infarct group, 14 in the risk factor group, and 29 normal subjects. Using axial T1-weighted MRI, cortical atrophy and ventricular enlargement (brain atrophy) were visually rated. Using axial T2-weighted MRI, WMHS was assessed in three categories: periventricular symmetrical, periventricular asymmetrical and subcortical. Using the mid-sagittal T1-weighted image, the CC was measured in its anterior, posterior, midanterior and midposterior portions. In the normal group, no correlations were noted between parameters. In the infarct group, there were significant correlations between CC and brain atrophy, and between CC atrophy and WMHS. After removing the effects of age, gender and brain atrophy, significant correlations were noted between some CC measures and subcortical WMHS. In the risk factor group, there were significant correlations between CC and brain atrophy and between CC atrophy and WMHS. After allowance for age, gender and brain atrophy, significant correlations between some CC measures and periventricular WMHS remained. The hypothesis that CC atrophy could be due to cerebral ischaemia was supported by other analyses. Namely, for correlations between the extent of infarcts and partial CC atrophy in patients with anterior middle cerebral artery (MCA) and with posterior MCA infarcts, there were significant correlations between the extent of infarct and midanterior CC atrophy in the former, and posterior CC atrophy in the latter. Our findings could indicate that CC atrophy is associated with cerebral ischaemia.
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 551-563 
    ISSN: 1432-1920
    Schlagwort(e): Key words Acquired immune deficiency syndrome ; Spine ; infections ; Spine ; neoplasms ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Our purpose was to describe the range of MRI findings in infectious and neoplastic involvement of the spine and spinal cord in symptomatic patients with the acquired immunodeficiency syndrome (AIDS). MRI studies in 55 patients with AIDS and neurological signs and symptoms thought to be related to the spine or spinal cord were reviewed. We categorized the findings according to the spinal compartment involved. There were 29 patients with extradural, 11 with intradural-extramedullary and 9 with intramedullary disease. In 6 patients more than one compartment was involved simultaneously, and patients presented with multiple lesions in the same compartment. The most common causes of extradural disease were bone lesions (28); an epidural mass was seen in 14 and spondylodiscitis in 4 patients. Cytomegalovirus polyradiculitis was the most common cause of intradural-extramedullary disease (in 10 cases); herpes radiculitis was seen in two, and tuberculous infection in another two. In three cases leptomeningeal contrast enhancement was due to lymphoma. Human immunodeficiency virus (HIV) myelitis was seen in two patients, presumed vacuolar myelopathy in two, toxoplasma myelitis in four, intramedullary lymphoma in one, and herpes myelitis in one. Familiarity with the various potential pathological entities that can affect the spine and spinal cord in the AIDS population and their imaging characteristics is crucial for initiation of further diagnostic tests and appropriate medical or surgical treatment.
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 643-647 
    ISSN: 1432-1920
    Schlagwort(e): Key words Progressive supranuclear palsy ; Magnetic resonance imaging ; Diffusion-weighted imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 42 (2000), S. 676-678 
    ISSN: 1432-1920
    Schlagwort(e): Key words. Syringomyelia, spontaneous drainage ; Cerebrospinal fluid, hydrodynamics ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. We present five cases of syringomyelia associated with Chiari I or other causes of partial obstructions at the cervicomedullary junction, with spontaneous disruption of the wall of a cervical syrinx and formation of a communication between the cavity and the subarachnoid space, shown on axial MRI. MRI can be used to investigate the hydrodynamics, showing the liquid inside the disrupted syrinx wall and the pathway of drainage. The finding of spontaneous drainage may be important for understanding the pathogenesis of syringomyelia and may be helpful for choosing a surgical approach.
    Materialart: Digitale Medien
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  • 116
    ISSN: 1432-198X
    Schlagwort(e): Key words Henoch-Schönlein purpura ; Methylprednisolone ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Neurological complications are rare during the course of Henoch-Schönlein purpura (HSP). We report a 7-year-old girl with HSP who presented with seizures, loss of vision and disturbance of consciousness. Magnetic resonance imaging (MRI) showed high signal intensity in the gray and white matter over the left parietal and both occipital lobes, compatible with MRI findings of cerebral vasculitis. The eye fundi revealed multiple branches of retinal artery occlusion. Intravenous pulse methylprednisolone (MTP) followed by oral steroid therapy was initially administered for HSP nephritis. Cerebral vasculitis developed 10 days post-MTP treatment, with progressive worsening of consciousness. Oral steroid was discontinued and plasmapheresis was performed alone. Her level of consciousness dramatically improved after plasmapheresis. The brain MRI and eye fundi findings were consistent with her clinical improvement. To the best of our knowledge, this is the first description of MRI abnormalities and multiple retinal artery branch occlusion of cerebral vasculitis in a patient with HSP that was successfully treated by plasmapheresis alone. In conclusion, we propose that plasmapheresis may be used as a first-line therapy or rescue therapy for cerebral vasculitis in HSP.
    Materialart: Digitale Medien
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  • 117
    Digitale Medien
    Digitale Medien
    Springer
    Pediatric nephrology 14 (2000), S. 990-992 
    ISSN: 1432-198X
    Schlagwort(e): Key words Hemolytic uremic syndrome ; Cerebral hypoxia ; Magnetic resonance imaging ; Central nervous system lesions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We report a 20-month-old girl with post- diarrheal (Shiga toxin) hemolytic uremic syndrome and severe encephalopathy. Magnetic resonance (MR) images were obtained in the acute phase of the disease and after 10 months. The first MR images showed widespread high signal intensity on T2-weighted and low signal intensity on T1-weighted images, in deep and subcortical white matter; the splenium of the corpus callosum was also involved, as well as cerebellar hemispheres. Neurological symptoms and signs gradually disappeared within 35 days. Follow-up MR imaging showed almost complete resolution of the previous findings, and the patient recovered without central nervous system impairment. The neurological lesions were probably due to hypoxia, although several other mechanisms could be involved, such as metabolic derangements and the action of Shiga toxin. In spite of the dramatic clinical manifestations, we observed a good outcome, indicating that patients with similar lesions do not necessarily have a poor prognosis.
    Materialart: Digitale Medien
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  • 118
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 40 (2000), S. 904-915 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Leber ; Sonographie ; Computertomographie ; Magnetresonanztomographie ; Szintigraphie ; Positronenemissionstomographie ; Keywords Liver ; Ultrasonography ; Computed tomography ; Magnetic resonance imaging ; Radionuclide imaging ; Positron emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Highly specific methods are required for the diagnostic workup of focal hepatic lesions, since benign circumscribed liver changes are very common. Although cross-sectional imaging techniques have a high diagnostic accuracy, radionuclide imaging techniques such as colloid, red blood cell, or hepatobiliary scan are commonly performed when a benign lesion is assumed since these permit a definite diagnosis with high specificity. The diagnosis of a primary or secondary malignant liver tumor, however, usually relies on radiological imaging techniques alone, supported by needle biopsy. Whether positron emission tomography as a primary or supplementary diagnostic tool will have a role in the routine staging of malignant tumors remains to be determined.
    Notizen: Zusammenfassung Die Abklärung umschriebener Leberveränderungen erfordert den Einsatz von Methoden hoher Spezifität, da die Prävalenz benigner, fokaler Läsionen sehr hoch ist. Hierfür sind radiologische Schnittbildtechniken grundsätzlich gut geeignet. Wenn aufgrund der sonographischen, computertomographischen oder magnetresonanztomographischen Befunde eine gutartige Läsion anzunehmen ist, werden jedoch häufig ergänzend die Kolloiderythrozyten- oder hepatobiliäre Szintigraphie – ggf. in Kombination – eingesetzt, da hiermit rasch eine abschließende Diagnose mit hoher Spezifität gestellt werden kann. Bei malignen primären oder sekundären Lebertumoren hingegen werden nuklearmedizinische Zusatzuntersuchungen seltener angefordert, da der radiologische Befund, ggf. gestützt durch eine Ultraschall- oder CT-gezielte Biopsie, eine Diagnose in den meisten Fällen erlaubt. Inwieweit sich der primäre oder ergänzende Einsatz der Positronenemissionstomographie im Vergleich zu radiologischen Schnittbildtechniken beim Staging bösartiger Tumoren bewährt, ist noch nicht abschließend geklärt.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 40 (2000), S. 1064-1076 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Sarkoidose ; Neurosarkoidose ; Granulom ; MRT ; Keywords Sarcoidosis ; Sarcoidosis complications ; Neurosarcoidosis ; Granuloma ; Brain diseases complications ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract The central nervous system is frequently affected during the course of sarcoidosis. Many of these lesions remain without clinical correlates. Unenhanced and contrast enhanced CT and MRI play an important role during the diagnostic work-up of patients with sarcoidosis and suspected or proved CNS involvement. This article summarizes the most frequent manifestations of neurosarcoidosis and provides illustrative examples of MRI findings.
    Notizen: Zusammenfassung Das Nervensystem ist bei der Sarkoidose häufiger mitbeteiligt als nach klinischen Gesichtspunkten zu vermuten wäre. Den bildgebenden Untersuchungsverfahren kommt eine große Bedeutung beim Nachweis der pathologischen Veränderungen zu. Insbesondere die Kernspintomographie sichert die Diagnosestellung und dient der Verlaufsbeurteilung. In dieser Übersichtsarbeit werden die typischen klinischen und bildgebenden Befunde bei der Neurosarkoidose vorgestellt.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 40 (2000), S. 870-877 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Lunge ; Perfusion ; Ventilation ; Computertomographie (CT) ; Magnetresonanztomographie (MRT) ; Keywords Lung ; Perfusion ; Ventilation ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Radiological cross-sectional imaging modalities, particularly computed tomography (CT) have become the mainstays for diagnosing lung disease in recent years. These enable morphological visualization of pathological processes with the greatest possible spatial resolution. Modern technical developments and complementary strategies have led to new applications and new functional assessments which need to be reviewed together with state-of-the-art techniques in nuclear imaging. The diagnosis of pulmonary embolism using spiral CT angiography and magnetic resonance (MR) angiography certainly belongs in this category. CT has become the an alternative modality of first choice, and it is also challenging pulmonary angiography as the gold standard. Direct visualization of patent pulmonary arteries and thromboembolic material is complemented by that of effects on the pulmonary parenchyma and right heart function; it also provides perfusion studies and MR-based flow measurement to assess hemodynamic compromise. Ventilation studies have long been a domain of nuclear imaging, and new techniques for the direct visualization of ventilation are emerging from recent developments in the field of MR imaging, for example, using hyperpolarized inert gases. New functional parameters of ventilation can be derived from these studies. For the diagnosis of metabolically active disease, such as tumor and pneumonia, CT offers very high sensitivity, for example, in screening for intrapulmonary nodules using low-dose CT and in the early detection of pulmonary infiltrates in high-risk patients. Especially for characterizing pulmonary nodules there is a need to combine nuclear medicine techniques, such as in positron-emission tomography.
    Notizen: Zusammenfassung Die radiologischen Schnittbildverfahren, insbesondere die CT, haben sich innerhalb kurzer Zeit einen herausragenden Stellenwert in der Diagnostik von Lungenerkrankungen erworben. Dies umfasst in erster Linie die morphologische Darstellung pathologischer Prozesse mit hoher räumlicher Auflösung. Moderne technische Entwicklungen und kombinierte Untersuchungsstrategien eröffnen neue Einsatzgebiete und auch funktionelle Aussagen, die nach einer aktuellen Standortbestimmung gemeinsam mit den nuklearmedizinischen Verfahren verlangen. Dazu gehört die Diagnostik der Lungenembolie mittels Spiral-CT-Angiographie und MR-Angiographie der Pulmonalarterien. Hier hat sich mittlerweile die CT als alternatives Verfahren der Wahl etabliert und die Rolle der Pulmonalisangiographie als Goldstandard infrage gestellt. Die reine direkte Darstellung der durchströmten Pulmonalarterien und des thromboembolischen Materials wird durch Diagnostik intrapulmonaler und kardialer Veränderungen, Perfusionsuntersuchungen sowie MR-basierte Flussmessungen zur hämodynamischen Beurteilung erweitert. Nachdem Untersuchungen der Ventilation lange Zeit eine Domäne der Nuklearmedizin waren, eröffnen aktuelle Entwicklungen in der MRT neue Verfahren zur direkten Visualisierung der Lungenbelüftung, z. B. mittels polarisierter Edelgase. Aus diesen Verfahren lassen sich auch neue funktionelle Parameter der Ventilation ableiten. In der Diagnostik von Tumoren und Entzündungen überzeugt die CT insbesondere durch ihre hohe Sensitivität, z. B. beim Screening auf intrapulmonale Rundherde mittels Niedrigdosis-CT oder bei der Früherkennung pneumonischer Infiltrate bei Risikopatienten. Insbesondere bei der Charakterisierung intrapulmonaler Rundherde ist eine Kombination mit nuklearmedizinischen Verfahren (PET) grundsätzlich anzustreben.
    Materialart: Digitale Medien
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  • 121
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter ; Koronare Herzkrankheit ; Magnetresonanztomographie ; Myokardperfusion ; SPECT ; Key words ; Coronary artery disease ; Magnetic resonance imaging ; Myocardial perfusion ; SPECT
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Aim: Performance of combined rest/stress MR perfusion studies and the analysis of qualitative signal intensity parameters in comparison with 99mTc-SestaMIBI SPECT in patients with known coronary artery disease (CAD). Methods: Sixteen patients with CAD underwent MR myocardial perfusion assessment at rest and after dipyridamole-induced hyperemia. Qualitative parameters (SI increase, SI upslope) of the SI time-curves were evaluated and characteristics of normal, reversible and persistent hypoperfused myocardium as assessed by 99mTc-SestaMIBI SPECT were compared. Results: Compared with the rest values, normal myocardium showed a significant increase of the SI upslope during hyperemia (P〈0.001), whereas persistent (P=0.07) and reversible (P=0.15) hypoperfusions showed only minor changes. SI increase over baseline also showed a significant increase only in normal myocardium (P〈0.001). At rest, reversible ischemic areas showed no significant differences from normal myocardium, whereas during hyperemia SI increase was significantly lower (P=0.02). Conclusions: Qualitative SI parameters of a combined rest/stress MR myocardial perfusion study allow to differentiate normal from reversibly or persistently hypoperfused myocardium.
    Notizen: Zusammenfassung Fragestellung: Die kombinierte Ruhe- und Belastungsuntersuchung der myokardialen Durchblutung in der MRT sowie die Analyse qualitativer SI-Parameter der MR-Myokardperfusion bei Patienten mit koronarer Herzkrankheit wurden mit der 99mTc-SestaMIBI SPECT verglichen. Methode: Bei 16 Patienten mit koronarer Herzkrankheit (KHK) wurde in der MRT mit einer Mehrschichtgradientenechotechnik die Myokardperfusion unter Ruhe- und Belastungsbedingungen untersucht. Qualitative Signalintensitätsparameter der Kontrastmittelanflutung wurden berechnet und die Parameter in normalen, reversibel und persistierend minderperfundierten Myokardarealen miteinander verglichen. Ergebnisse: Normales Myokard zeigte im Gegensatz zu reversiblen (P=0,15) und persistierenden (P=0,07) Ischämien eine signifikante Zunahme der SI-Anstiegssteilheit unter Belastung (P〈0,001). Die SI-Zunahme zeigte ebenfalls nur in normal perfundierten Arealen eine signifikante Zunahme (P〈0,001) nach Belastung. Unter Belastung zeigte sich bei reversiblen Ischämien eine signifikant niedrigere SI-Zunahme als in normalem Myokard (P=0,02), während sich in Ruhe kein Unterschied zeigte. Schlussfolgerung: Qualitative SI-Parameter der kombinierten MR-Perfusionsuntersuchung des Myokards in Ruhe und unter Belastung erlauben die Differenzierung zwischen normalem sowie reversibel oder persistierend minderperfundiertem Myokard.
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  • 122
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 40 (2000), S. 465-468 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Fäkale Inkontinenz ; Magnetresonanztomographie ; Endoanalspule ; Key words Faecal incontinence ; Magnetic resonance imaging ; Endoanal coil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Purpose. Within the recent years several studies have been performed to determine the value of endoanal magnetic resonance imaging (MRI) in faecal incontinence. Methods. MRI is performed using a 0.5 – 1.5T unit. A surface coil with a maximum diameter of 19 mm is placed in the anal canal. T2* 3D gradient-echo-sequences and T2-weighted turbo-spin-echo-sequences in coronal, axial und sagittal orientation are acquired. Results. Compared to endoanal ultrasound (EUS), which is the gold standard for diagnosis in faecal incontinence, endoanal MRI is better in visualization of the external sphincter. The accurate delineation of the external sphincter has led to the possibility to evaluate sphincter atrophy. Preliminary results have shown, that endoanal MRI has an accuracy of 90–95% in the demonstration of lesions in the external sphincter. In detection of lesions of the internal sphincter EUS is still superior to endoanal MRI. Conclusion. EUS and endoanal MRI are currently the optimal imaging techniques for faecal incontinenc, with the advantage of detecting external sphincter atrophy with endoanal MRI.
    Notizen: Zusammenfassung Zielsetzung. In den letzten Jahren wurden mehrere Studien durchgeführt, deren Ziel es war, den Stellenwert von Endoanalspulen in der Magnetresonanztomographie (MRT) zur Abklärung von Sphinkterdefekten bei fäkaler Inkontinenz (FI) zu bestimmen. Methode. Die endoanale MRT wird an 0,5–1,5-Tesla-Geräten durchgeführt. Zur Darstellung der Sphinkteren werden Oberflächenspulen mit einem maximalen Querdurchmesser von 19 mm endoanal appliziert. T2*-gewichtet 3D-Gradientenechosequenzen und T2-gewichtete Turbospinechosequenzen in koronaler, axialer und sagittaler Schnittführung werden zur Darstellung des Analkanals angefertigt. Ergebnisse. Im Vergleich zum endoanalen Ultraschall (EUS), der den Goldstandard bei der Abklärung einer FI darstellt, kann mit der endoanalen MRT v. a. der M. sphincter externus besser abgegrenzt werden. Die exakte Differenzierung des M. sphincter externus vom ischiorektalem Fettgewebe ermöglicht die Diagnose einer Atrophie des äußeren Schließmuskels. Erste Studienergebnisse haben gezeigt, daß die endoanale MRT eine Treffsicherheit von 90–95% bei der Detektion von Defekten im M. sphincter externus erreicht. Die Abklärung einer Kontinuitätsunterbrechung im M. sphincter internus ist nach wie vor eine Domäne des EUS. Schlussfolgerung. Die endoanale MRT stellt eine ergänzende Methode zum EUS dar und ist diesem in der Beurteilung der Morphologie des M. sphincter externus überlegen.
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  • 123
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 40 (2000), S. 625-631 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Computertomographie ; Magnetresonanztomographie ; Pharynx ; Tumoren ; Key words Computed tomography ; Magnetic resonance imaging ; Pharynx ; Tumors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Background. Malignant tumors of the head and neck region are amongst the six most often occurring tumors of the body. They can be associated with the different anatomical compartments as well as different histologic types. The way of tumor spread of these malignancies depends on their histologic type and on the region. These compartments can be separated into the nasopharynx, the oropharynx, and the hypopharynx. Most of the malignant tumors belong to the squamous cell carcinomas, other histologic types are depicted less frequently. The histologic types of the other groups which are seen more often comprise of lymphomas and adenoidcystic carcinomas. The undifferentiated carcinoma of the nasopharynx is supposed to be a special type of tumor. The malignant tumors of the pharynx can also involve all three compartments. Beside these tumors, malignancies of mesenchymal origin can also be delineated. Imaging modalities. The imaging modalities most frequently used to detect these tumors and to clarify their extension are contrast enhanced computed tomography, magnetic resonance imaging, nuclearmedicine imaging modalities such as positron emission tomography. Other scintigraphic imaging methods play a less important role. Conclusion. The different imaging modalities of malignant pharyngeal tumors and of potentially infiltrated lymphnodes with the weightness on computed tomography and magnetic resonance imaging and their appearance in these imaging techniques shall be enhanced in this paper.
    Notizen: Zusammenfassung Hintergrund. Der Kopf-Hals-Bereich zählt weltweit zu den 6 am häufigsten von malignen Tumoren befallenen Körperregionen. Maligne Tumoren des Pharynx können dabei entsprechend der anatomischen Unterteilung – d. h. Nasopharynx, Oropharynx und Hypopharynx – diesen Regionen zugeordnet werden. Neben der grundsätzlich heterogenen Wachstumstendenz weisen diese Tumoren je nach histologischer Herkunft ein recht unterschiedliches Ausbreitungsmuster auf. Bei der überwiegenden Mehrzahl handelt es sich um Plattenepithelkarzinome, die anderen histologischen Typen – wie adenoidzystische Karzinome oder Lymphome – sind weitaus seltener vertreten. Daneben kommen sehr selten auch noch maligne Tumoren mesenchymalen Ursprungs wie z. B. die Rhabdomyosarkome vor. Bildgebung. Die bildgebende Abklärung erfolgt mit der kontrastmittelverstärkten CT, der MRT und in jüngster Zeit mit nuklearmedizinischen Methoden, z. B. PET. Andere szintigraphische Untersuchungsmethoden spielen eine untergeordnete Rolle. Resümee. Verschiedene bildgebende Methoden (schwerpunktmäßig CT und MRT) und die entsprechenden Erscheinungsbilder sowie Lokalisations- bzw. Ausbreitungsdiagnostik der malignen Tumoren und evtl. befallener Lymphknoten dieser Regionen werden vorgestellt.
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  • 124
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Zerebrovaskuläre Erkrankung ; Arteriosklerose ; Magnetresonanztomographie ; Magnetresonanzangiographie ; Digitale Subtraktionsangiographie ; A. carotis ; Keywords Cerebrovascular disease ; Arteriosclerosis ; Magnetic resonance imaging ; Magnetic resonance angiography ; Digital subtraction angiography ; Carotid artery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Purpose. To compare high resolution contrast-enhanced MR angiography (MRA) and digital subtraction angiography (DSA) in the assessment of supraaortic vessel stenosis. Methods. 14 patients with suspicion of cerebrovascular disease or upper limb ischemia underwent selective DSA and high resolution contrast enhanced MRA employing a new Panoramic-Array coil. Stenosis assessment in comparison to DSA followed NASCET criteria. Additionally signal-/noise ratios (SNR) were evaluated to assess contrast enhancement. Results. Diagnostic image quality was achieved in all patients. Sensitivity and specificity for assessing high-grade stenosis of the supraaortic vessels were 100% and 96% respectively. In the assessment of high-grade common or internal carotid artery stenosis sensitivity and specificity was 100%. Conclusion. High resolution contrast enhanced supraaortic MRA combined with new coil sytems allow for a reliable assessment of stenoses along the whole vessel course including the aortic arch. Previous stent procedures limit its use in post-interventional follow-up.
    Notizen: Zusammenfassung Fragestellung. Ziel der Studie war ein Vergleich zwischen hochauflösender kontrastverstärkter MR-Angiographie (MRA) und digitaler Subtraktionsangiographie (DSA) in der Diagnostik von Stenosen der supraaortalen Gefäße. Methoden. 14 Patienten mit Verdacht auf eine zerebrovaskuläre Erkrankung oder Durchblutungsstörung der oberen Extremität wurden mit DSA und hochaufgelöster, kontrastverstärkter MR-Angiographie mit Verwendung einer Panoramic-Array-Spule untersucht. Neben der Beurteilung der Kontrastierung erfolgte die Bestimmung der Stenosegrade im Vergleich zur selektiven DSA nach den NASCET-Kriterien. Ergebnisse. Bei allen Patienten konnte mit der MRA eine diagnostisch ausreichende Bildqualität erzielt werden. In der Diagnostik hochgradiger Stenosen der supraaortalen Gefäße ergab sich eine Sensitivität von 100% und eine Spezifität von 96%. In der Erkennung hochgradiger Stenosen der A. carotis communis oder interna lagen Sensitivität und Spezifität bei 100%. Schlussfolgerung. Die ultraschnelle MRA der supraaortalen Gefäße in Kombination mit einer geeigneten Spulenkombination ermöglicht die zuverlässige Erkennung stenotischer Veränderungen im gesamten Gefäßverlauf einschließlich des Aortenbogens. Stentimplanationen limitieren derzeit den Einsatz in der postinterventionellen Kontrolle.
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  • 125
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurology 247 (2000), S. 943-948 
    ISSN: 1432-1459
    Schlagwort(e): Key words Transverse myelitis ; Motor evoked potentials ; Somatosensory evoked potentials ; Electromyography ; Prognosis ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A systematic evaluation of anterior horn cell, motor and sensory pathways is possible by electromyography (EMG), motor (MEPs) and somatosensory (SEPs) evoked potentials, respectively, which may provide valuable information on acute transverse myelitis (ATM). In a prospective hospital-based study, EMG, MEP and SEP studies were carried out on admission and after 3 months in 39 patients with ATM. All the patients also underwent detailed clinical evaluation, and spinal magnetic resonance imaging (MRI) was performed in 28. Outcome was defined at the end of 3 months as poor, partial or complete recovery on the basis of functional status. Spinal MRI revealed hyperintense signal changes in T2 extending for two segments to the entire spinal cord. Central motor conduction time to tibialis anterior (CMCT-TA) was more frequently abnormal (90%), followed by tibial SEP (77%). CMCT to abductor digiti minimi (ADM) was abnormal in 30% and median SEP in 15% of patients. Evidence of denervation on EMG was present in 51% of patients. The CMCT-TA improved in 48% patients and tibial SEP in 32%. Median SEP improved in all patients, and CMCT-ADM remained prolonged in two. At 3 months 2 patients had died, and 18 had poor, 10 partial and 9 complete recovery. CMCT was correlated with miscle power, tone, reflec and MRI changes. Patients' outcome of was correlated with CMCT, SEP and EMG. These results are consistent with pronounced involvement of dorsal region of spinal cord in ATM. MEP is more frequently abnormal than SEP.
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  • 126
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurology 247 (2000), S. 252-258 
    ISSN: 1432-1459
    Schlagwort(e): Key words Cerebral venous ¶thrombosis ; Dural sinuses ; Magnetic resonance imaging ; Heparin ; Thrombolysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In contrast to arterial stroke, cerebral venous thrombosis (CVT) is an infrequent condition which presents with a wide spectrum of signs and with a highly variable mode of onset. The clinician must therefore consider it systematically in all brain syndromes and perform the appropriate neuroimaging investigations: computed tomography (CT) with computed tomography angiography and/or magnetic resonance imaging with magnetic resonance angiography and, if necessary intra-arterial angiography. Once the diagnosis is established, a wide investigation for should be carried out in search of the cause, and treatment started as soon as possible. Treatment is based on the combination of intravenous heparin (followed by oral anticoagulants for 3–6 months), symptomatic treatment (anticonvulsants, analgesics, treatment of increased intracranial pressure) and treatment of the cause. Local thrombolysis is indicated if there is deterioration due to thrombosis extension despite adequate anticoagulation. Diagnosis and treatment of CVT should be considered as an emergency because of the considerable potential for full recovery in this condition.
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  • 127
    ISSN: 1432-1459
    Schlagwort(e): Key words Multiple sclerosis ; Neuropsychological ; Cognitive ; Magnetic resonance imaging ; Lesion load
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Neuropsychological deficits and the relationship to brain pathology were examined in 13 primary progressive (PP) and 12 secondary progressive (SP) multiple sclerosis patients with a similar duration of the progressive phase and comparable physical disability. A battery of neuropsychological tests to assess attention, short-term and working memory was administered to the patients, and their performance was compared to that of 20 healthy controls matched for age and premorbid IQ. Total cerebral lesion load on T2-weighted magnetic resonance imaging was measured in the patients. Both PP and SP patients performed significantly worse than controls in most of the neuropsychological tests. There were only subtle differences between SP and PP on the working memory task although magnetic resonance imaging lesion load was significantly higher in SP than in PP patients. In this exploratory study only subtle differences in cognitive impairment were detected between SP and PP patients matched for physical disability and relevant illness features. The results also suggest that the severity of cognitive impairment cannot be fully explained by the extent of abnormalities detected on conventional T2-weighted magnetic resonance images, and that other pathological abnormalities such as in normal-appearing white matter are likely to be involved.
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  • 128
    ISSN: 1432-1459
    Schlagwort(e): Key words Leukoaraiosis ; Aged ; Atherosclerosis ; Magnetic resonance imaging ; Carotid artery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cerebral white matter lesions are frequently observed on magnetic resonance imaging of elderly, nondemented persons. There is evidence that white matter lesions are involved in the pathophysiology of cognitive decline and dementia. White matter lesions can be divided into those in the periventricular and those in the subcortical region. Pathological and epidemiological studies suggest that atherosclerosis is involved in the pathogenesis of these lesions. Our study reports on the association between atherosclerosis in the carotid arteries and white matter lesions in a population-based study among 1077 elderly subjects. We randomly sampled 1077 subjects aged between 60–90 years from two prospective population-based studies. All subjects underwent ultrasonography of the carotid artery. In addition, 1.5 T magnetic resonance imaging was performed; white matter lesions in the subcortical and periventricular regions were rated separately. With increasing number of plaques in the carotid artery the severity of periventricular white matter lesions increased (P trend = 0.03), but not the severity of subcortical white matter lesions (P trend = 0.19). In addition, an increase in intima media thickness was borderline significantly associated with an increased severity of periventricular white matter lesions (P trend = 0.09), but not of subcortical white matter lesions (P trend = 0.68). These findings suggest that partly dissimilar pathogenetic mechanisms are involved in the etiology of periventricular and subcortical white matter lesions.
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  • 129
    ISSN: 1432-1459
    Schlagwort(e): Key words Multiple sclerosis ; Fatigue ; Magnetic resonance imaging ; Motor evoked potentials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Fatique is a common symptom of multiple sclerosis (MS) even in the early phases of the disease, when neurological disability is usually still not present. To investigate the pathophysiology of fatigue we compared neurophysiological (motor evoked potentials of the four limbs, MEPs) and brain magnetic resonance imaging (MRI) findings in two groups of nondisabled MS patients, those with (n=15) and those without (n=15) fatigue. Fatigue was assessed by an interview and scored by the Fatigue Severity Scale. The two groups were matched for sex, age, disease duration, Expanded Disability Status Scale score, pyramidal Functional System (FS) score, and depression score. MEPs were abnormal in five patients with fatigue and in one patient without fatigue. A significant association was found between the patient scores on the Fatigue Severity Scale, and the burden of MRI lesions (r=0.5; P〈0.005). Significantly higher parietal lobe (P〈0.05), internal capsule (P〈0.05), and periventricular trigone (P〈0.05) lesion loads were found in patients with fatigue than in those without. Our results agree with a central nervous system origin of fatigue in MS patients. This symptom might be a consequence either of a functional deafferentation of the cortex due to cortico-subcortical interconnection damage or of a demyelination in critical sites of the CNS, such as the cortico-spinal tract.
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  • 130
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurology 247 (2000), S. 280-285 
    ISSN: 1432-1459
    Schlagwort(e): Key words Small subcortical ¶infarction ; Large-vessel disease ; Magnetic resonance imaging ; Silent white-matter hyperintensity ; Lacunar infarction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Small subcortical infarctions resulting from large-vessel disease are often observed. It is important to distinguish these from pure lacunar infarction resulting from small-vessel disease because the investigations and examinations differ. We investigated the differences on brain magnetic resonance imaging (MRI) between small subcortical ¶“lacunar-like” infarcts resulting from large-vessel disease and pure lacunar infarcts. Thirteen subjects with small lacunar-like infarcts (size 〈 2 cm), resulting from large-vessel disease, ¶and 30 subjects with lacunar infarcts (〈 2 cm), without large-vessel disease were studied. We measured infarction size using a 1.5-T MRI device and evaluated silent subcortical hyperintensity lesions using the modified Scheltens’ score. Large-vessel lesion was confirmed by conventional angiography, duplex carotid scan, and magnetic resonance angiography. There was no difference in the mean age of the two groups. Cerebrovascular risk factors and atherosclerotic complications were also comparable for the two groups. Progressive stroke was more common ¶in the lacunar-like infarction group than in the lacunar infarction group ¶(P = 0.004). Scores for periventricular hyperintensity, white matter hyperintensity, basal ganglia hyperintensity, and total subcortical hyperintensity scores were significantly higher in the lacunar infarction group than in the lacunar-like infarction group. The difference in basal ganglia hyperintensity scores was remarkable (P = 0.001). The enlargement of the perivascular space was also significantly greater in the lacunar infarction group than in the lacunar-like infarction group. These findings seem to reflect differences in the pathogenesis of infarction between the two groups. Silent subcortical hyperintensity lesions and enlargement of perivascular space are useful for between distinguishing small lacunar-like infarct resulting from large-vessel disease and pure lacunar infarction. This may have significant implications for the management of patients with lacunar-sized infarctions. It suggests that the pathogenesis of lacunar-sized infarction is variable.
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  • 131
    ISSN: 1432-1459
    Schlagwort(e): Key words Sarcoidosis ; Spinal cord ; Magnetic resonance imaging ; Corticosteroid therapy ; Prognosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Spinal cord sarcoidosis is a rare disorder whose natural history and therapeutic outcome are not fully known. We examined four patients with spinal cord sarcoidosis both clinically and radiologically, particularly in relation to corticosteroid treatment. The initial manifestation was cervical myelopathy in three and uveitis in one. All four patients progressed slowly until corticosteroid therapy was initiated. The cervial spine was involved in all patients. Magnetic resonance imaging (MRI) showed spinal cord swelling with T2-weighted high intensity and linear leptomeningeal and patchy or diffuse intramedullary enhancement with gadolinium diethylene triaminepentaacetic acid. With corticosteroid therapy, dramatic improvement was seen on MRI, including disappearance or marked reduction of swelling and enhancement. Plasma levels of angiotensin-converting enzyme (ACE) were also markedly improved. In contrast, the clinical symptoms were little improved in one patient, unchanged in two, and rather worsened in one patient. Recurrence was seen on MRI at the maintenance dose in all four patients, without any dramatic change in clinical manifestation. MRI findings and plasma ACE are well correlated with active leasion of the spinal cord sarcoidosis, providing a useful marker for recurrence, but do not parallel the clinical manifestations.
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  • 132
    Digitale Medien
    Digitale Medien
    Springer
    Skeletal radiology 29 (2000), S. 726-728 
    ISSN: 1432-2161
    Schlagwort(e): Keywords Developmental dysplasia ; Hip ; Membrane ; Interposition ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Intra-articular membranous interposition was detected by MRI in the hip joint with residual subluxation of a girl aged 5 years 10 months. This structure, which had low signal intensity on both T1- and T2-weighted images, separated the femoral head from the acetabulum. Histological examination revealed chondrometaplasia, which suggested that this interposition might be transformed to a surface cartilaginous tissue of the secondary acetabulum often observed in residual subluxation of the hip.
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  • 133
    ISSN: 1432-2161
    Schlagwort(e): Key words Rheumatoid arthritis ; Cervical spine ; Magnetic resonance imaging ; Dynamic imaging ; Flexion views
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Objective. To determine whether MR imaging in flexion adds value relative to imaging in the neutral position with respect to displaying involvement of the subarachnoid space, brainstem and spinal cord. Design and patients. T1-weighted MR images of the cervical spine in 42 rheumatoid arthritis patients with cervical spine involvement were obtained and analyzed prospectively. We assessed changes between images obtained in the neutral position and following active flexion, especially horizontal atlantoaxial and subaxial motion, presence or absence of brainstem compression, subarachnoid space involvement at the atlantoaxial and subaxial level and the cervicomedullary angle. Vertical atlantoaxial subluxation and the amount of pannus were correlated with motion and change in subarachnoid space. Results. The flexion images showed horizontal atlantoaxial motion in 21 patients and subaxial motion in one patient. The flexion view displayed brainstem compression in only one patient. Involvement of the subarachnoid space increased at the atlantoaxial level in eight (19%) patients (P=0.004) and at the level below C2 in five (12%) patients (P=0.03). There were no patients with a normal subarachnoid space in neutral position and compression in the flexed position. The cervicomedullary angle changed significantly with flexion. Vertical atlantoaxial subluxation and the amount of pannus did not show a significant correlation with motion or subarachnoid space involvement. Conclusion. MR imaging in the flexed position shows a statistically significant narrowing of the subarachnoid space at the atlantoaxial level and below C2. Cord compression is only observed on flexion views if the subarachnoid space in neutral position is already decreased. MR imaging in the flexed position might be useful, since subarachnoid space involvement may be an indicator for the development of neurologic dysfunction.
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  • 134
    Digitale Medien
    Digitale Medien
    Springer
    Skeletal radiology 29 (2000), S. 104-108 
    ISSN: 1432-2161
    Schlagwort(e): Key words Adult teratoma ; Dumb-bell type tumor ; Lumbar spine ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We report a case of a lumbar teratoma in a 50-year-old woman. The teratoma showed a dumb-bell-type expansion at the level of the left L3/4 foramen with massive erosion of the L3 vertebral body. MRI revealed inhomogeneous signal changes in the tumor, which were histologically compatible with a mixture of bone, muscle, fat, and cyst containing sebaceous material. Complete resection of the tumor and spinal arthrodesis with pedicle screw fixation was necessary to obtain stability of the affected spinal segment.
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  • 135
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 16 (2000), S. 138-142 
    ISSN: 1433-0350
    Schlagwort(e): Key words Craniopharyngioma ; Posterior fossa tumors ; Microsurgery ; Magnetic resonance imaging ; Computerized tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Between 1991 and 1998, 24 patients underwent surgery for a craniopharyngioma in our department. This group included two patients who had tumors with extensive growth along the midline, and along the posterior fossa in particular. In both cases suprasellar calcifications were typical features on magnetic resonance imaging (MRI) and computed tomography (CT). A 7-year-old boy presented with a 6-month history of headache, nausea, and progressive unilateral hearing loss. With a suboccipital approach it was possible to remove the main part of the tumor. In a 13-year-old boy headache and visual deterioration led to the diagnosis of a craniopharyngioma, which was removed with a pterional approach. For the neuroimaging work-up in such cases of atypically growing craniopharyngiomas MRI is the method of choice. Additional CT scanning is recommended, which provides valuable information about bony changes at the skull base due to space-occupying growth. CT substantiates the differential diagnosis if typical calcifications are seen.
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  • 136
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 16 (2000), S. 398-401 
    ISSN: 1433-0350
    Schlagwort(e): Keywords Primitive neuroectodermal tumor ; Diffuse leptomeningeal neoplasia ; Magnetic resonance imaging ; Pseudotumor cerebri ; Sinus thrombosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Primitive neuroectodermal tumors are easily detected by neuroradiologic imaging, as a rule. We report on two patients with early diffuse leptomeningeal primitive neuroectodermal tumors which escaped detection by contrast-enhanced magnetic resonance imaging.
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 16 (2000), S. 551-554 
    ISSN: 1433-0350
    Schlagwort(e): Keywords Acute myelitis of childhood ; Fibrocartilaginous embolism ; Magnetic resonance imaging ; Spinal cord infarction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Fibrocartilaginous embolus causing acute spinal cord infarction is a rare cause of acute-onset paraplegia or quadriplegia. Few cases of survivors have been reported in the neurosurgical literature, with most reports involving post-mortem or biopsy findings. There is little information on MRI findings in such patients. We present the youngest patient ever reported, and discuss the important differences between fibrocartilaginous embolus and acute myelitis of childhood. A 6-year-old girl with a history of back pain presented with sudden-onset nontraumatic paraplegia, with a clinical anterior spinal artery syndrome. Initial MRI scan revealed intervertebral disc disease at L1–2 and an incidental thoracic syrinx, but no cause for her acute-onset paraplegia was identified. Cerebrospinal fluid and other investigations were all negative. Sequential MRI scans revealed development of spinal cord expansion from T10 to the conus medullaris, with increased cord signal in the anterior aspect of the spinal cord. The intervertebral disc disease was unchanged. The imaging and clinical findings were caused by fibrocartilaginous embolus, which meant there was no need for spinal cord biopsy. The report describes the clinical and imaging criteria for diagnosis of fibrocartilaginous embolus, highlighting the case for avoiding an unnecessary biopsy. The clinical pattern in the paediatric group is discussed, with features differentiating it from acute myelitis of childhood.
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  • 138
    ISSN: 1433-0350
    Schlagwort(e): Keywords Cavernous angioma ; Cerebral angiography ; Dynamic scan ; Magnetic resonance imaging ; Sinus pericranii
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Objects: Sinus pericranii is only a symptom complex, and it can have a variety of etiologies. Therefore, it is important to differentiate these etiologies preoperatively by means of radiological examinations. A 5-year-old boy was admitted with a soft and fluctuant tumor in the right parietal region near the midline. The tumor appeared when the child was in a recumbent position, distending noticeably with the Valsalva maneuver and disappearing completely when the patient was in the sitting position. Methods: Magnetic resonance imaging showed the lesion with honeycomb-like heterogeneous iso- and low-intensity signals on the T1-weighted image and with heterogeneous high- and iso- intensity signal on the T2-weighted image. Dynamic study with an injection of gadolinium diethylene-triaminopentaacetic acid demonstrated and nodular peripheral enhancement at early phase and subsequent progressive enhancement towards the center of tumor. The internal carotid angiogram was normal. The external carotid angiogram, however, showed a tumor stain fed by the superficial temporal arteries. The stain was retained until the late phase and drained into the scalp veins and into the superior sagittal sinus. Following direct injection of contrast medium into the tumor there was prolonged retention of the medium in the tumor and leakage into scalp veins and the superior sagittal sinus. The mass under the periosteum was totally removed and proved to be a cavernous angioma. Conclusions: Scalp cavernous angioma is one of the etiologies of sinus pericranii and may be diagnosed preoperatively by cerebral angiography or magnetic resonance imaging. Serial dynamic magnetic resonance imaging will be particularly helpful for this diagnosis.
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  • 139
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Diffusionsgewichtete Kernspintomographie ; Wirbelkörpermetastasen ; Diffusionskoeffizient ; Keywords Diffusion weighted imaging (DWI) ; Magnetic resonance imaging ; Vertebral metastases ; Diffusion coefficient ; ADC
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Aim of the study. The aim of the study was the evaluation of the diffusion coefficient (ADC) of vertebral metastasis and regular vertebral bodies with diffusion weighted MRI (DWI). DWI evaluates the tissue-specific molecular diffusion of protons. In tissues with high cell densities (neoplasm) a decreased ADC can be expected due to restricted diffusion according to an exaggerated amount of intra- and intercellular membranes (i. e. diffusion barriers). Methods. In 5 breast cancer patients the ADC of both known vertebral metastases and of adjacent regular vertebral bodies were measured with DWI (1.0 T; Phased-Array-Body-Coil; b: 880 and 440 s/mm2). Results. The ADC of regular vertebral bodies (1.3±0.23×10–,3s/mm2) was significantly (p≤0.0002) higher than in vertebral metastases (0.39±0.11×10–3s/mm2). Conclusions. These data demonstrate that the ADC can be reliably measured in vertebral bodies. The quantitative evaluation of the ADC in vertebral bodies seems to be an objective and comparable parameter for differentiating malign from benign vertebral tissue.
    Notizen: Zusammenfassung Ziel. Ziel der Arbeit war die Messung des Diffusionskoeffizienten (ADC) mittels diffusionsgewichteter (DW) MRT in Wirbelkörpermetastasen und in MR-morphologisch unauffälligen Wirbelkörpern. Die DW-MRT misst den für ein Gewebe spezifischen ADC, welcher der Eigendiffusion von Wasserstoffmolekülen entspricht. In zellreichem Tumorgewebe mit zahlreichen intra- und interzellulären Membranen (d. h. Diffusionsbarrieren) ist ein niedriger, in zellarmen oder nekrotischem Gewebe, ein hoher ADC zu erwarten. Methode. Bei 5 Patientinnen mit Mammakarzinom wurde der ADC von Lendenwirbelkörpermetastasen sowie von angrenzenden, MR-morphologisch unauffälligen Wirbelkörpern ermittelt (1,0 T; Phased-Array-Body-Coil; b: 880 und 440 s/mm2). Ergebnisse. Der ADC in MR-morphologisch unauffälligen Wirbelkörpern (1,3±0,23×10–3s/mm2) war signifikant (p≤0,0002) höher als in Wirbelkörpermetastasen (0,39±0,11×10–3s/mm2). Schlussfolgerung. Anhand dieser Daten konnte gezeigt werden, dass der ADC von Wirbelkörpern verlässlich gemessen werden kann, und dass durch die quantitative Bestimmung des ADC ein objektiv vergleichbarer Parameter zur Verfügung steht, der zur Differenzierung von malignem und benignem Gewebe gut geeignet erscheint.
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  • 140
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Diffusion ; Magnetresonanztomographie ; Encephalitis disseminata ; Keywords Diffusion ; Magnetic resonance imaging ; Multiple sclerosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Magnetic resonance (MR) imaging is one of the best methods in diagnosis of multiple sclerosis, particularly in disclosure of active demyelinating lesions. Aim of this study was to compare diffusion weighted imaging and contrast enhancement in the detection of active lesions. A MR study with a contrast enhanced T1-weighted pulse sequence with magnetization transfer presaturation and a diffusion weighted echoplanar pulse sequence (b=1000 s/mm2) was performed in 17 patients (11 women, 6 men) with multiple sclerosis. 29 of 239 lesions showed an increased signal intensity in diffusion weighted imaging, 24 lesions a contrast enhancement, but only 16 lesions were visible in both pulse sequences. In patients with short clinical symptomatology significant more lesions could be detected with diffusion-weighted pulse sequence in comparison to patients with long standing symptomatology showing more lesions with contrast enhancement. Hence it is likely, that both pulse sequences detect different histopathologic changes. The early detection of demyelinating lesions in diffusion weighted imaging is attributed to the extracellular edema, however the contrast enhancement is caused by a blood brain barrier abnormality. It can be expected that diffusion weighted imaging will have a high impact on imaging of multiple sclerosis not only in therapeutic trials, but also in clinical routine.
    Notizen: Zusammenfassung Die Magnetresonanztomograpie ist eine der wichtigsten Untersuchungsmethoden in der Diagnostik der Encephalitis disseminata, insbesondere im Nachweis aktiver Entmarkungsherde. Ziel der Untersuchung war es, diffusionsgewichtete und kontrastverstärkte Untersuchungen bezüglich der Erkennung aktiver Läsionen zu vergleichen. Bei 17 Patienten (11 Frauen, 6 Männer) mit bekannter Encephalitis disseminata wurden sowohl eine kontrastverstärkte T1-gewichtete Sequenz mit Magnetization-Transfer-Sättigung als auch eine diffusionsgewichtete Echoplanar-Sequenz (b=1000 s/mm2) durchgeführt. 29 der 239 Läsionen zeigten eine Signalsteigerung in der diffusionsgewichteten Sequenz, 24 eine Kontrastmittelaufnahme, jedoch waren nur 16 Läsionen in beiden Techniken nachweisbar. Bei Patienten mit kurzzeitig bestehender Symptomatik zeigten sich signifikant mehr Entmarkungsherde mit Signalsteigerung in der Diffusionswichtung im Vergleich zu Patienten mit länger bestehender neurologischer Symptomatik, die mehr kontrastmittelaffine Läsionen aufwiesen. Dies lässt darauf schließen, dass mit beiden Verfahren unterschiedliche histopathologische Veränderungen beobachtet werden. Das sehr frühe Auftreten der Diffusionsänderung in den Entmarkungsherden wird auf das Ödem zurückgeführt, während die Kontrastmittelaufnahme durch eine Blut-Hirnschranken-Störung verursacht wird. Es ist zu erwarten, dass die diffusionsgewichtete Magnetresonanztomographie einen hohen Stellenwert in der Bildgebung der Encephalitis disseminata nicht nur in Therapiestudien, sondern auch in der klinischen Routinediagnostik erlangen wird.
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  • 141
    ISSN: 1433-7347
    Schlagwort(e): Key words Osteonecrosis ; Bone marrow edema ; Knee ; High tibial osteotomy ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Sportwissenschaft
    Notizen: Abstract Symptoms in patients suffering from spontaneous osteonecrosis of the knee (SONK) may be reduced by high tibial osteotomy (HTO). However, the fate of the necrotic lesion is unknown and needs further investigation. We conducted a prospective study to evaluate magnetic resonance imaging (MRI) changes after operative and nonoperative treatment. Ten consecutive patients suffering from SONK of the medial compartment were given two treatment options: either HTO (n = 6) or conservative treatment with partial weight bearing for 3 months (n = 4). We measured the greatest extent of well-defined subchondral low signal intensity abnormality, considered to represent necrosis, and the surrounding area of intermediate signal intensity, considered to represent perifocal bone marrow edema, on T1-weighted coronal MRI images before and after treatment. The MRI follow-up period was 17.5 months (range 12–¶27) in the HTO group and 14.5 months (range 8–25) in the nonoperative group. At follow-up the MRI evaluation revealed a decrease in the low signal intense areas (necrosis) in five of the six patients in the HTO group. Only one of the four nonoperative patients showed a decrease in the low signal intense area. The intermediate intense areas (edema) decreased in all patients in the HTO group and in three of four in the nonoperative group. The mean decrease in the area of perifocal edema was significantly greater in the HTO group than in the nonoperative group (P = 0.019). No statistically significant difference was found for the area of necrosis between the two groups (P = 0.171). A clinical improvement was observed in all patients of the HTO group but in only two of the four patients of the nonoperative group. We conclude that the decrease in perifocal bone marrow edema seems to be associated with improved patient comfort. The MRI appearance of the necrotic lesion does not alter with either treatment mode.
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  • 142
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 16 (2000), S. 829-831 
    ISSN: 1433-0350
    Schlagwort(e): Keywords Intraoperative imaging ; Magnetic resonance imaging ; Anatomical and functional neuronavigation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The Erlangen-concept of image-guided-surgery is based on the installation of an open magnetic resonance (MR) scanner (Magnetom Open, 0.2 T, Siemens AG) in a twin operating room in combination with two neuronavigation systems (Stealth NeuroStation, Sofamor Danek, MKM Zeiss). Since March 1996 this method has been used for a total of 402 patients, among them 44 children. In 214 patients, mainly with gliomas or pituitary adenomas or who needed surgery for epilepsy, we performed intraoperative MR imaging to monitor the extent of resection, allowing a second look for possible tumor remnants and also compensating for brain shift by an intraoperative update of neuronavigation. Functional neuronavigation, i.e. the combination of anatomical neuronavigation with functional imaging [e.g. magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI)] was used in patients with lesions in brain areas such as the motor and speech areas. For MEG we used a MAGNES II biomagnetometer (Biomagnetic Technologies, San Diego, Calif.) and for fMRI a 1.5 T Siemens Symphony MR scanner. So far we have treated 89 patients with functional neuronavigation. Our preliminary experience indicates that intraoperative MR imaging, especially in combination with functional neuronavigation, allows more radical resections with lower morbidity.
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  • 143
    Digitale Medien
    Digitale Medien
    Springer
    European archives of psychiatry and clinical neuroscience 250 (2000), S. 76-78 
    ISSN: 1433-8491
    Schlagwort(e): Key words Septum pellucidum ; Developmental ¶disorder ; Schizophrenia ; Magnetic resonance imaging ; Cavum veli interpositi ; Cavum septi pellucidi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The case of monocygotic twins discordant for a psychotic disorder is presented. An anomaly of the septum pellucidum, a so-called cavum veli interpositi was found in the psychotic twin while his brother showed no such anomaly. Previous studies have shown a higher prevalence of septum pellucidum anomalies in schizophrenic patients. Abnormalities of the septum pellucidum may be associated with disturbed neuronal development in distinct limbic brain areas which cannot yet be visualized yet by brain imaging techniques. The finding of the cavum veli interpositi in the psychotic twin could be incidental; however, it may indicate a dysgenic process in early brain development and, thus, play a significant role in the etiology of psychosis.
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  • 144
    Digitale Medien
    Digitale Medien
    Springer
    Herz 25 (2000), S. 384-391 
    ISSN: 1615-6692
    Schlagwort(e): Key Words Cardiomyopathy ; Magnetic resonance imaging ; Schlüsselwörter Kardiomyopathie ; Magnetresonanztomographie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die kardiale Magnetresonanztomographie (MRT) bietet als nichtinvasives Verfahren die Möglichkeit, innerhalb einer Untersuchung die für die verschiedenen Formen der Kardiomyopathien charakteristischen funktionellen und morphologischen Veränderungen darzustellen. In dieser Übersicht werden die Einsatzmöglichkeiten der MRT bei den verschiedenen Formen dieser Erkrankung diskutiert. Die geringe Variabilität der MRT-Messungen gestattet ge-naue Verlaufskontrollen im klinischen Alltag, eröffnet aber auch die Möglichkeit, Therapiestudien mit einer geringeren Anzahl von einzuschließenden Patienten zu sicheren Ergebnissen zu führen. Damit erweitert sich das Spektrum der Indikationen über die Präzisierung unklarer Befunde hinaus auf die Verlaufsbeobachtung während einer pharmakologischen Intervention und auf alle wissenschaftlichen Fragestellungen. Der Vorzug der MRT, nichtinvasiv Gewebe charakterisieren zu können, verdeutlicht das Potential dieser Technik bei sekundären Kardiomyopathien sowie bei entzündlichen und infiltrativen Formen myokardialer Erkrankungen.
    Notizen: Abstract Cardiac magnetic resonance imaging (MRI) is a noninvasive tool which is able to diagnose and differentiate cardiomyopathies in a single study. The assessment of essential information such as alterations of myocardial and ventricular geometry and function is possible with a high degree of accuracy and reproducibility, based on a small inter- and intraobserver variability. Thus, very small morphological and functional changes in different types of cardiomyopathy are detectable, thereby enabling the cardiologist to increase the safety of therapeutic decisions. Furthermore, MRI bears the potential to characterize tissue transformation in the different types of myocardial affections including ischemic, toxic, infiltrative or inflammatory forms.
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  • 145
    Digitale Medien
    Digitale Medien
    Springer
    Heart and vessels 15 (2000), S. 44-45 
    ISSN: 1615-2573
    Schlagwort(e): Key words Pericardial hydatid cyst ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 146
    ISSN: 1615-2573
    Schlagwort(e): Key words Three-dimensional echocardiography ; Magnetic resonance imaging ; Left ventricular volume ; Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The objective of this study was to investigate the degree of bias with coaxial three-dimensional echocardiography in an experimental animal setup and to establish the minimum number of sections needed for estimation of left ventricular (LV) volume. Epicardial coaxial echocardiography and magnetic resonance imaging (MRI) was used to measure LV volume in 14 pigs, with chronic remodeled left ventricles induced by repeated intracoronary microembolizations. In addition, six animals underwent serial MRI at baseline, immediately after intracoronary microembolization, and after 119–165 days (mean 129 days). Coaxial echocardiography was performed by rotational acquisition of long-axis sections starting from an arbitrary angle. Planimetered MRI contours of LV endocardial borders were analyzed to investigate the relationship between the number of coaxial sections, and the precision of volume estimates. The mean ± 2SD of the differences between coaxial epicardial echocardiography with six sections and MRI were −2.5 ± 16.4 ml, 0.8 ± 13. 1 ml, and 2% ± 14% for end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF), respectively. Numerical analysis conducted on MRI contours of LV endocardial borders showed that with six coaxial sections the average coeffi-cient of error was 〈1% for the EDV and ESV. Three-dimensional echocardiography with six coaxial sections provides unbiased LV volume estimation with minimal geometric error.
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  • 147
    ISSN: 1439-6327
    Schlagwort(e): Key words Human ; Muscle function ; Physiological cross-sectional area ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The purpose of the present study was to investigate the effect of recruitment on the relationship between peak torque and physiological cross-sectional area (PCSA) in human muscle. A group of 11 healthy men participated in this study. Isokinetic knee extension torques at seven (0, 30, 60, 120, 180, 240, and 300° · s−1) velocities were determined. Magnetic resonance imaging (MRI) was performed to calculate PCSA of right quadriceps femoris (QF) muscle. Exercise-induced contrast shifts in spin-spin relaxation time (T2)-weighted MRI were taken at rest and immediately after repetitive knee-extension exercise and T2 of QF were calculated. The MRI pixels with T2 values more than 1 SD greater than the means at rest were considered to represent QF muscle that had contracted. The area of activated PCSA within the total in QF was expressed as percentage activated PCSA and used as an index of muscle recruitment. The PCSA correlated with peak torque at 0° · s−1 (r=0.615, P 〈 0.05); in contrast, activated PCSA correlated with peak torque at 120° · s−1 (r=0.603, P 〈 0.05) and 180° · s−1 (r=0.606, P 〈 0.05). Additionally, there was a significant difference in correlation coefficients between the activated PCSA-peak torque relationship and the PCSA-torque relationship (P 〈 0.05). These results suggested that muscle recruitment affects the PCSA-torque relationship.
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  • 148
    Digitale Medien
    Digitale Medien
    Springer
    European journal of applied physiology 82 (2000), S. 391-396 
    ISSN: 1439-6327
    Schlagwort(e): Key words B-mode ultrasound ; Bioelectrical impedance ; Data acquisition system ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The present study aimed to investigate the validity of bioelectrical impedance and ultrasonographic methods for predicting the muscle volume of the upper arm. Bioelectrical impedance of the right upper arm and the thickness of elbow flexor and extensor muscles were measured from 26 healthy young adult men using a specially designed bioelectrical impedance data acquisition system and brightness-mode ultrasound apparatus, respectively. As reference data, the muscle volume (MVMRI) of the right upper arm was determined using a magnetic resonance imaging method. The impedance index was calculated as L 2/Z, where L is the upper arm length and Z is the impedance of the shoulder to the elbow. The muscle volume (MVULT) was calculated as π·(d/2)2·L, where d is muscle thickness. L 2/Z and MVULT were significantly correlated with MVMRI with correlation coefficients of 0.971 and 0.962, respectively. In these relationships, the standard errors of estimation were 44.2 cm3 (6.3%) for L 2/Z and 50.7 cm3 (7.2%) for MVULT. There was no significant difference between the absolute errors of muscle volumes estimated by L 2/Z and MVULT: 36.2 (4.8, SEM) cm3 for L 2/Z versus 40.3 (5.8) cm3 for MVULT. The present results suggest that both bioelectrical impedance and ultrasonographic methods may be useful for predicting the muscle volume of the upper arm.
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  • 149
    ISSN: 1615-6692
    Schlagwort(e): Key Words Right ventricle ; Arrhythmias ; Left bundle branch block ; Dysplasia ; Fatty infiltration ; Magnetic resonance imaging ; Schlüsselwörter Rechter Ventrikel ; Arrhythmien ; Linksschenkelblock ; Dysplasie ; Fettige Degeneration ; Kernspintomographie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die arrhythogene rechtsventrikuläre Dysplasie (ARVD), eine Herzmuskelerkrankung unlarer Ätiologie, ist pathologisch durch fettige Degeneration des rechtsventrikulären Myokards gekennzeichnet. Die klinischen Symptome umfassen strukturelle und funktionelle Malformationen des rechten Ventrikels, krankhafte elektrokardiographische Befunde und das Auftreten ventrikulärer Tachykardien mit Linksschenkelblock oder plötzlichem Herztod. Die Krankheit tritt familiär gehäft auf und wird autosomal vererbt. Neben der rechtsventrikulären Dilatation stellen rechtsventrikuläre Aneurysmen typische Fehlbildungen bei ARVD dar. Sie sind im so genannten “Dysplasiedreieck”, das heißt rechtem ventrikulärem Ausflusstrakt, Herzspitze und Infundibulum, verteilt. Dort lokalisierte ventrikuläre Aneurysmen können als pathognomonisch für die ARVD angesehen werden. Ein weiteres typisches Merkmal der ARVD ist die fettige Degeneration der freien rechten Ventrikelwand. Diese funktionellen und strukturellen Charakteristika sind bei der klinischen Untersuchung mit bildgebenden Verfahren wie Kontrastangiographie, Echokardiographie, Radionuklidangiographie, ultraschneller Computertomographie und Magnetresonanztomographie (MRT) von Bedeutung. Unter diesen Verfahren erlaubt die MRT die deutlichste Darstellung des Herzens, insbesondere bei Beteiligung des rechten Ventrikels, der sich mit den anderen bildgebenden Methoden in der Regel schwerer untersuchen lässt. Darüber hinaus bietet die MRT den wesentlichen Vorteil der Darstellung der fettigen Degeneration als helles Signal im rechtsventrikulären Myokard. Die MRT liefert die wichtigsten anatomischen, funktionellen und morphologischen Kriterien zur Diagnose einer ARVD in einem einzigen Untersuchungsgang. Daher scheint sie das beste bildgebende Verfahren zur Identifizierung und Nachsorge von Patienten mit klinischem Verdacht auf ARVD zu sein.
    Notizen: Abstract Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disorder of unknown cause that is characterized pathologically by fibrofatty replacement of the right ventricular myocardium. Clinical manifestations include structural and functional malformations of the right ventricle, electrocardiographic abnormalities, and presentation with ventricular tachycardias with left bundle branch pattern or sudden death. The disease is often familial with an autosomal inheritance. In addition to right ventricular dilatation, right ventricular aneurysms are typical deformities of ARVD and they are distributed in the so-called “triangle of dysplasia”, i. e., right ventricular outflow tract, apex, and infundibulum. Ventricular aneurysms at these sites can be considered pathognomonic of ARVD. Another typical hallmark of ARVD is fibrofatty infiltration of the right ventricular free wall. These functional and morphologic characteristics are relevant to clinical imaging investigations such as contrast angiography, echocardiography, radionuclide angiography, ultrafast computed tomography, and magnetic resonance imaging (MRI). Among these techniques, MRI allows the clearest visualization of the heart, in particular because the right ventricle is involved, which is usually more difficult to explore with the other imaging modalities. Furthermore, MRI offers the specific advantage of visualizing adipose infiltration as a bright signal of the right ventricular myocardium. MRI provides the most important anatomic, functional, and morphologic criteria for diagnosis of ARVD within one single study. As a result, MRI appears to be the optimal imaging technique for detecting and following patients with clinical suspicion of ARVD.
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  • 150
    ISSN: 1573-9686
    Schlagwort(e): Heart ; Left ventricle ; LV contractility ; ESPVR ; Pig ; Rat ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract The end systolic pressure–volume relation (ESPVR) has been shown to be a relatively load independent measure of left ventricular (LV) contractility. Recently, several single-beat ESPVR computation methods have been developed, enabling the quantification of LV contractility without the need to alter vascular loading conditions on the heart. Using a single-beat ESPVR method, which has been validated previously in humans and assumes that normalized elastance is constant between individuals of a species, we studied the effects of myocardial infarction on LV contractility in two species, the rat and the pig. In our studies, LV pressure was acquired invasively and LV volume determined noninvasively with magnetic resonance imaging, at one week postinfarction in pigs and at 12 weeks postinfarction in rats. Normalized systolic elastance curves in both animal species were not statistically different from that of humans. Also, the slope of the ESPVR $$\left( {E_{es} } \right)$$ decreased significantly following infarction in both species, while the volume-axis intercept $$\left( {V_0 } \right)$$ was unaffected. These results indicate that a single-beat ESPVR method can be used to measure the inotropic response of the heart to myocardial infarction, and that the basis for this method (i.e., constant normalized elastance) is applicable to a variety of mammalian species. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8761Lh, 8719Hh, 8719Rr, 8719Ff
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  • 151
    ISSN: 1439-099X
    Schlagwort(e): Schlüsselwörter: Strahlentherapieplanung ; Stereotaxie ; Magnetresonanztomographie ; FLAIR-Bildgebung ; Gliome ; Metastasen ; Key Words: Radiotherapy planning ; Stereotaxie ; Magnetic resonance imaging ; FLAIR imaging ; Glioma ; Metastases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Background: FLAIR MR imaging has shown to be a valuable imaging modality in pathologic lesions of the brain including intraaxial brain tumors. The aim of the study was to assess the value of a FLAIR technique in the planning process of stereotactic radiotherapy in patients with cerebral gliomas and metastases. Patients and Methods: Thirty-five patients with cerebral gliomas and 12 patients with a total of 39 cerebral metastases were examined by T2/PD-weighted fast spin-echo, fast FLAIR prior and after contrast and contrast enhanced T1-weighted spin-echo using identical slice parameters. The images were evaluated by using quantitative and qualitative criteria. Quantitative criteria were tumor-to-background and tumor-to-cerebrospinal fluid contrast and contrast-to-noise. The qualitative evaluation was performed as a multireader analysis concerning lesion detection, lesion delineation and image artifacts. Results: In the qualitative evaluation (Tables 3 and 6), all readers found the fast FLAIR images to be superior to fast spin-echo in the exact delineation of cerebral tumors (p 〈 0.001) and the delineation of enhancing and non enhancing tumor parts. Fast FLAIR was superior in the delineation of cortically located and small lesions but was limited in lesions adjacent to the ventricles. Fast FLAIR provided a significantly better tumor-to-CSF contrast and tumor-to-CSF contrast-to-noise (p 〈 0.001) (Tables 1, 2a, 2b, 4, 5). The tumor-to-background contrast and tumor-to-background contrast-to-noise of the fast FLAIR images were lower than that of T2-weighted spin-echo images but were significantly increased after the application of contrast media. FLAIR images had more image artifacts, but the image interpretation was not influenced. Conclusions: FLAIR MR imaging was found to be a valuable sequence in the planning protocol of stereotactic radiotherapy. The concurrent presentation of enhancing and non enhancing tumor tissue on contrast enhanced fast FLAIR imaging enables to use a single imaging sequence in the treatment protocol. This enables to load a reduced image amount into the radiotherapy planning software, is therefore time saving and reduces potential errors.
    Notizen: Hintergrund: Eine FLAIR-(fluid attenuated inversion recovery-)Sequenz wurde in der stereotaktischen Strahlentherapieplanung zerebraler Gliome und Metastasen im Vergleich zu konventionellen Spin-Echo-(SE-)Sequenzen eingesetzt. Überprüft wurde die Wertigkeit dieser Methode anhand der Läsionserkennbarkeit, Läsionsabgrenzung und des Tumorkontrastes. Patientengut und Methode: 35 Patienten mit zerebralen Gliomen und zwölf Patienten mit insgesamt 39 zerebralen Metastasen wurden mit einer FLAIR-Sequenz vor und nach Kontrastmittel, einer T2- und PD-gewichteten SE-(FSE-)Sequenz und einer kontrastmittelunterstützten T1-gewichteten SE-Sequenz untersucht. Eine quantitative Auswertung umfaßte Tumor-zu-Hintergrund- und Tumor-zu-Liquor-Kontrast und Kontrast-zu-Rausch-Bestimmungen. In einer qualitativen Auswertung wurden die Erkennbarkeit und Abgrenzung der Tumoren anhand einer Multireader-Analyse beurteilt. Ergebnisse: Der Tumor-zu-Hintergrund-Kontrast bei zerebralen Gliomen war auf den nativen FLAIR-Aufnahmen den konventionellen FSE-Aufnahmen unterlegen. Beide Reader fanden die FLAIR-Technik aufgrund der Liquorunterdrückung in der Läsionsabgrenzung der T2- und Protonen-gewichteten FSE-Technik hingegen überlegen. Nach Kontrastmittelgabe stieg das Signal bei anreichernden Tumoren auf den FLAIR-Bildern im Mittel um 49%, wodurch der Tumor-zu-Hintergrund-Kontrast den der konventionellen Aufnahmen signifikant (p 〈 0,001) übertraf. Durch die Kontrastmittelgabe wurde auch die Abgrenzung der infiltrativen Tumoranteile signifikant (p 〈 0,001) verbessert. Bei Patienten mit zerebralen Metastasen konnten mittels kontrastmittelunterstützter FLAIR-Aufnahmen signifikant mehr Metastasen als mit nativer FLAIR- und T2/PD-gewichteter FSE-Sequenz, jedoch weniger als mittels kontrastmittelverstärkter T1 SE-Sequenz erkannt werden. Der Nachteil lag hierbei in der geringen Detektionsrate bei sehr kleinen, subkortikal gelegenen Metastasen. Vorteil der Methode war jedoch wie bei den zerebralen Gliomen die gleichzeitige Darstellung von anreicherndem Tumor und umgebendem Ödem. Artefakte nahe der Liquorräume sind auf FLAIR-Bildern häufig, sie störten die Bildinterpretation jedoch nicht wesentlich. Signalhyperintensitäten aufgrund physiologischer Gliosezonen an den Ventrikelrändern sind ebenfalls häufig zu beobachten und müssen in die Bildinterpretation einbezogen werden. Schlußfolgerung: Zusammengefaßt bietet sich die FLAIR-Technik als eine wertvolle Bildgebungssequenz in der stereotaktischen Strahlentherapieplanung von zerebralen Tumoren an. Durch die Verwendung kontrastmittelunterstützter FLAIR-Technik kann sowohl die Definition der radiologischen als auch der makroskopischen Tumorränder auf einer einzigen Bildgebungssequenz erreicht werden. Dieses ist insbesondere für das Einladen der Bilddaten in die verwendeten Bestrahlungsplanungssysteme von Vorteil, da die Bilddatenmenge deutlich reduziert, der Arbeitsaufwand für zusätzliche Bildfusionen vermindert und mögliche Fehlerquellen bei der Bildfusion vermieden werden können.
    Materialart: Digitale Medien
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  • 152
    Digitale Medien
    Digitale Medien
    Springer
    Modern rheumatology 10 (2000), S. 150-154 
    ISSN: 1439-7609
    Schlagwort(e): Key words Extensibility ; Supraspinatus muscle ; Tendon fiber ; Rotator cuff tear ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract An estimate of the extensibility of the supraspinatus muscle after a rotator cuff tear is useful in selecting the most appropriate operative procedure and the prognosis after surgery. We studied the relationship between the morphological findings of the supraspinatus muscle on magnetic resonance imaging and its elongation length. Twenty-one shoulders of 20 patients with massive rotator cuff tears were scanned parallel to the long axis of the supraspinatus muscle. The ratio of the largest width of the supraspinatus muscle belly to the distance from the greater tuberosity to the proximal end of the supraspinatus muscle was termed the supraspinatus muscle belly ratio. The appearance of linear bands and the degree of retraction of the tendon of the supraspinatus muscle were analyzed. The extensibility of the supraspinatus muscle decreased when the degree of retracted tendon was high, while no correlation was found with the length of the rotator cuff defect, the supraspinatus muscle belly ratio, or the appearance of linear bands.
    Materialart: Digitale Medien
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  • 153
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 257 (2000), S. 24-26 
    ISSN: 1434-4726
    Schlagwort(e): Key words Pharyngeal neoplasms ; Rhabdomyoma ; Magnetic resonance imaging ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Adult rhabdomyomas of the head and neck are uncommon benign skeletal muscle tumors. Only a few cases occurring in the pharyngeal wall have been described in the world literature. We present a case of recurrent bilateral rhabdomyomas in the pharynx and discuss the clinicopathological features of this lesion, comparing it to those of other neoplasms from which it must be differentiated. To our knowledge, bilaterality of this type of lesion has not been described previously. Although adult rhabdomyomas have a distinct histology, they often are mistaken for a variety of other lesions, particularly granular cell tumor.
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    Springer
    Brain tumor pathology 17 (2000), S. 97-103 
    ISSN: 1861-387X
    Schlagwort(e): Intracranial plasma cell granuloma ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Plasma cell granulomas (PCGs) are benign, inflammatory masses of unknown etiology composed of polyclonal mature plasma and lymphoid cells. The lung is their most common location, and occurrence within the cranial cavity is extremely rare. We report the case of an 11-year-old girl who presented with seizures and was diagnosed as having a dural-based right frontal tumor that extended toward the sagittal sinus and the falx. The lesion was totally excised, together with the abnormal dura. A limited cortical excision was also performed using electrocorticographic guidance. Histopathologic diagnosis of intracranial plasma cell granuloma was reached after extensive immunohistochemical tests and electron microscopy. This is the third case of PCG with description of changes in the neighboring cerebral tissue. Although PCGs are well-circumscribed lesions, lymphoplasmocytic inflammation, neuronal loss, and reactive gliosis occur within the adjacent cortex. Disturbed cortical lamination, as we have observed, appears to be a histological finding that has not been described previously.
    Materialart: Digitale Medien
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  • 155
    Digitale Medien
    Digitale Medien
    Springer
    Neurological sciences 21 (2000), S. S865 
    ISSN: 1590-3478
    Schlagwort(e): Key words Optic neuritis ; Multiple sclerosis ; Magnetic resonance imaging ; CSF examination ; Oligoclonal bands ; Evoked potentials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We evaluated the risk of developing clinically definite multiple sclerosis (CDMS) after acute isolated optic neuritis in 102 patients in a follow-up study (duration 6.5±2.0 years). The probability of CDMS was 13% after 2 years, 30% after 4 years, 38% after 6 years, and 49% after 8 and 10 years. CDMS occurred in 42 (59%) of 71 patients with brain lesions detected with magnetic resonance imaging (MRI). No patient with normal MRI exam developed the disease. Patients with 3 or more MRI-detected lesions presented a shorter first interattack interval and a higher relapse rate compared to subjects with only 1 or 2 lesions. The predictive value of CSF examination and of evoked potentials was poor.
    Materialart: Digitale Medien
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  • 156
    Digitale Medien
    Digitale Medien
    Springer
    Neurological sciences 21 (2000), S. S877 
    ISSN: 1590-3478
    Schlagwort(e): Key words Multiple sclerosis ; Magnetic resonance imaging ; Magnetization transfer imaging ; Diffusion-weighted imaging.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Conventional magnetic resonance imaging (MRI) has markedly increased our ability to detect the macroscopic abnormalities of the brain and spinal cord in patients with multiple sclerosis (MS). Magnetization transfer imaging and diffusion-weighted imaging have the potential to provide relevant and complementary information on the structural changes occurring within and outside these lesions and are contributing significantly to our understanding of the mechanisms leading to the accumulation of irreversible neurological disability in MS patients. These present review will summarize the major results achieved with the application of these two MR techniques to the assessment of the evolution of MS.
    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    Springer
    Neurological sciences 21 (2000), S. 103-108 
    ISSN: 1590-3478
    Schlagwort(e): Key wordsL-2-Hydroxyglutaric aciduria ; Magnetic resonance imaging ; Leukodystrophy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract L-2-Hydroxyglutaric aciduria is a rare inborn error of metabolism, marked by a large and persistent increase of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid (CSF). We present clinical, biochemical and neuroradiological findings of seven Italian patients aged 4–19 years presenting at different stages of the disease. The disorder was characterized by a progressive neurological syndrome with cerebellar and pyramidal signs, mental deterioration, epilepsy and subcortical leukoencephalopathy on magnetic resonance imaging (MRI). We observed a good correlation between the severity of the disease and the extent of lesions on MRI. We report the result of the first positive prenatal diagnosis.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 28 (2000), S. 934-944 
    ISSN: 1573-9686
    Schlagwort(e): Magnetic resonance imaging ; Diffusion imaging ; Fiber orientation ; Ventricular geometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract An imaging method for the rapid reconstruction of fiber orientation throughout the cardiac ventricles is described. In this method, gradient-recalled acquisition in the steady-state (GRASS) imaging is used to measure ventricular geometry in formaldehyde-fixed hearts at high spatial resolution. Diffusion-tensor magnetic resonance imaging (DTMRI) is then used to estimate fiber orientation as the principle eigenvector of the diffusion tensor measured at each image voxel in these same hearts. DTMRI-based estimates of fiber orientation in formaldehyde-fixed tissue are shown to agree closely with those measured using histological techniques, and evidence is presented suggesting that diffusion tensor tertiary eigenvectors may specify the orientation of ventricular laminar sheets. Using a semiautomated software tool called HEARTWORKS, a set of smooth contours approximating the epicardial and endocardial boundaries in each GRASS short-axis section are estimated. These contours are then interconnected to form a volumetric model of the cardiac ventricles. DTMRI-based estimates of fiber orientation are interpolated into these volumetric models, yielding reconstructions of cardiac ventricular fiber orientation based on at least an order of magnitude more sampling points than can be obtained using manual reconstruction methods. © 2000 Biomedical Engineering Society. PAC00: 8761-c, 8757Gg
    Materialart: Digitale Medien
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  • 159
    ISSN: 1434-193X
    Schlagwort(e): Triplet recombination ; Electron transfer ; Radical ions ; Photochemistry ; Terpenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The triphenypyrylium tetrafluoroborate (TPT)-sensitized reactions of several terpene donor molecules, including sabinene (1), α-phellandrene (4), α-terpinene (5) and γ-terpinene (6) give rise to significantly different products than reactions induced by other electron-transfer sensitizers, such as 1,4-dicyanobenzene (DCB). The divergent reactions require decidedly different key intermediates; the products obtained with TPT can be explained by dissociative recombination of the intermediate radical-radical cation pair in the triplet state, generating donor-derived biradicals.
    Materialart: Digitale Medien
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  • 160
    ISSN: 1434-193X
    Schlagwort(e): Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Polycycles ; Ring expansion ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---2-Alkyl-1-methylquinazolinium hexafluorophosphates 9 are deprotonated by sodium or potassium hydride to afford solutions of 2-alkylidenedihydroquinazolines 10, which were investigated by NMR spectroscopy. Trapping with methanesulfonyl azide (5a) of 10 in situ or subsequent treatment with trifluoromethanesulfonyl azide (5b) gives mixtures of colourless (15) and intensely yellow N-sulfonylimino-1,4-benzodiazepines 16 along with products due to cleavage of the exocyclic double bond of 10, viz. 11 and 13. The ethylidene compound 10b yields the bicyclic products 18 and 19, apparently by complex sequences of reactions that are triggered by removal of the acidic proton at C-2 of 16b and 16f. The structures of the products are based on spectroscopic evidence and X-ray diffraction analyses performed on 15b, 16d, 16e, and 19.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 161
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1589-1593 
    ISSN: 1434-193X
    Schlagwort(e): Azaallenium ions ; Azaallylium ions ; Iminium ion ; Kinetics ; Linear Free Energy Relationships ; Ab initio calculations ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The rate constants for the reactions of the 2-azaallenium ion 1b+, the 2-azaallylium ion 2a+ and the iminium ion 3+ with different nucleophiles were determined by 1H NMR spectroscopy. By correlation with the Linear Free Enthalpy Relationship (LFER) lg k20°C = s (E + N), developed by Mayr and Patz, the electrophilicity parameters E(1b+) = -3.7, E(2a+) ≍ -16 and E(3+) = -10.43 were obtained. They show that the relative reactivities of these ions are approximately 1012:1:106. Quantum chemical calculations (ab initio, DFT) of the methyl anion affinities for the ions 1b+,2a+ and3+ are in agreement with the experimental E values. The X-ray structure of 3+·CF3SO3- is reported for the first time; it shows no strong interaction between the cation and the anion.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 162
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1595-1601 
    ISSN: 1434-193X
    Schlagwort(e): Oxazoline N-oxide ; Cycloadditions ; Cycloadditions ; Lactams ; Thienamycin ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---[3+2] Cycloaddition between a camphor-derived oxazoline N-oxide 9 and the γ,δ-unsaturated enamino ester 11 afforded the single adduct 6. A stereoselective reduction of the enamino ester side chain allowed the control of the absolute configuration of the two additional asymmetric centres. Nitrogen protection and oxidative hydrolysis of the resulting product 13, followed by further functional group manipulations, led to the β-lactam derivative 1, a known precursor of the β-methylthienamycin derivative2a.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 163
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1603-1607 
    ISSN: 1434-193X
    Schlagwort(e): Boron ; Cyclotrimerizations ; Nitrogen heterocycles ; Macrocycles ; Subphthalocyanines ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The regioselective preparation of ortho-substituted subphthalocyanides was achieved employing 3-substituted phthalonitrile derivatives as starting materials. A mechanistic proposal has been outlined.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99525_s.pdf or from the author.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 164
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1609-1615 
    ISSN: 1434-193X
    Schlagwort(e): Terpenoids ; Natural products ; Total synthesis ; Cyclizations ; Rearrangements ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A new route for the synthesis of 2,7- and 7-functionalized labdanes starts from (R)-carvone (1). 11-Nordrim-7-en-9-one (15) is an appropriate starting material for the total synthesis of hispanone (21), a biologically active furolabdane isolated from the Mediterranean medicinal plant Ballota saxatilis.
    Materialart: Digitale Medien
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  • 165
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1623-1626 
    ISSN: 1434-193X
    Schlagwort(e): Iridoid glucoside ; (8S)-Kingiside ; (8S)-Loganin ; (8S)-7-Ketologanin ; Asymmetric synthesis ; Natural products ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The tetraacetyl derivative 8 of the naturally occurring kingiside (8a) was prepared from aucubin (1). Intermediates in the synthesis were (8S)-tetraacetyl loganin (6) and (8S)-tetraacetyl-7-ketologanin (7), whose free (8R)-epimers occur in many different plants (Caprifoliaceae, Loganiaceae). The 13C NMR spectrum allows the structure to be unequivocally identified.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 166
    ISSN: 1434-193X
    Schlagwort(e): Tetrakis(dimethylamino)naphthalenes ; Basicity ; Hydrogen bonds ; Cyclicvoltammetry ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---For comparison to the recently described 2,3,6,7-tetrakis(dimethylamino)naphthalene (1) the three isomers 2,3, and 4 were synthesized. The basicities of this group of isomers are strongly dependent upon the different mutual orientations of the pairs of dimethylamino substituents: only the isomers 3 and, partially, 4, both with dimethylamino groups in adjacent peri-positions of the naphthalene, are strong “proton sponges”. For the isomers 1 and 2 with the same number and kind of twofold dimethylamino substituents in neighbouring ortho-positions, however, no significant basicity increase is observed. To explain this difference between the two groups of isomers it is suggested that in the ortho-pairs of 1 and 2 the C-N bonds diverge considerably, leading to an increased N···N distance and consequently to less stable [N···H···N]+ hydrogen bonds in contrast to the parallel C-N bonds in the peri-substituted isomers 3 and 4. X-ray crystal structure analyses of the bases and of some of the salts derived therefrom were solved and are discussed. Cyclic voltammetry indicates that 1 to 4 are strong electron donors, reacting easily to radical cations or dications which with suitable acids have been obtained as salts.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 167
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1677-1683 
    ISSN: 1434-193X
    Schlagwort(e): Radicals ; Cyclizations ; Pyridinethione ; Tetrahydrofurans ; Asymmetric synthesis ; Thiazolethione ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The trisubstituted functionalized tetrahydrofurans 10, 11, 16, 18, and 19 were photochemically prepared from 2,3-syn- and 2,3-anti-configuredN-(3-benzoyloxy-5-hexen-2-oxy)thiazole-2(3H)-thione anti-6, pyridinethiones 7, anti-8, and BrCCl3. The formation of tetrahydrofurans was achieved by an efficient and highly regioselective alkoxyl radical cyclization (5-exo-trig). The 2,3-anti substituted intermediates 9 and 12 cyclize stereoselectively whereas a 2,3-syn-configured O-radical affords both possible diastereomeric addition products in equal amounts. The cyclized tetrahydrofuryl methyl radicals were trapped with the bromine atom donor BrCCl3 to afford the bromomethyl-substituted cyclic ethers 10, 11, 18, and 19 in excellent yields. The utility of this reaction was stressed by conversion of one of the newly prepared tetrahydrofurans in a two-step synthesis into (+)-allo-muscarine (+)-20.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99590_s.pdf or from the author.
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  • 168
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1685-1694 
    ISSN: 1434-193X
    Schlagwort(e): Thioketones ; Thiocarbonyl ylides ; Cycloadditions ; Cycloreversions ; Sulfur heterocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Reactions of diaryl thioketones with diazomethane at room temperature afford 4,4,5,5-tetraaryl-1,3-dithiolanes; the scope of this surprising 2:1 interaction has been studied for decades (Schönberg Reaction). The clue to the mechanism was our observation that the stoichiometry is 1:1 at -78 °C, and 2,5-dihydro-2,2-diaryl-1,3,4-thiadiazoles are formed as primary [2+3] cycloadducts. They lose N2 at -45 °C in first-order reactions generating diaryl thioketone S-methylides which can be intercepted by thioketones (→1,3-dithiolanes), multiple CC bonds, or acids HX. In the absence of trapping reagents, the elusive intermediates either dimerize furnishing 2,2,3,3-tetraaryl-1,4-dithianes or give rise to 2,2-diarylthiiranes by electrocyclization. Beyond thiobenzophenone and diazomethane, our main model reaction, the studies involve fluorene-9-thione, 4,4-dimethoxy- and 4,4-dichlorothiobenzophenone. The ring of 2,5-dihydro-2,2-diphenyl-1,3,4-thiadiazole (8) is opened by LDA at -78 °C and derivatives of anion 12 are obtained. - In summa: The Schönberg reaction consists of two 1,3-dipolar cycloadditions, linked by a 1,3-dipolar cycloreversion.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 169
    ISSN: 1434-193X
    Schlagwort(e): Conjugation ; Boron ; Sensors ; Cyclic voltammetry ; Polymers ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---New electropolymerizable aromatic compounds (i.e. pyrrole, thiophene, aniline) bearing boronic acid and ester substituents have been synthesized and their electrochemical behavior has been investigated. Functionalized polythiophene and polypyrrole films could be anodically generated in acetonitrile, whereas the polyaniline derivative was electroformed in an acidic aqueous solution. The electrochemical responses of some of these materials were changed when fluoride ions were added to the electrolytic solutions. The strongest modifications, caused by binding of fluoride by the immobilized boron, were observed for the polypyrrole derivative in hydroorganic media.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 170
    ISSN: 1434-193X
    Schlagwort(e): Heterocycles ; Zinc ; Palladium ; Catalysts ; Sulfur ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Organozinc halides derived from Grignard reagents behave differently in their reaction with ethyl (±±)-(2RS,3SR)-tetrahydro-4-methylene-2-phenyl-3-(phenylsulfonyl)furan-3-carboxylate (3) according to the hybridisation of the carbon ligand. During the development of short multi-component reactions for the synthesis of diverse functionalized ethyl 2,5-dihydrofuran-3-carboxylates it was discovered that aryl and vinyl zinc halides undergo clean reaction with 3 in the presence of Pd(PPh3)4. In contrast, when alkyl zinc halides are reacted with 3 in the presence of Pd(PPh3)4, reductive desulfonation of 3 is observed. Remarkably, in the absence of a transition metal catalyst, the allylic substitution of 3 with alkyl zinc halides proceeds cleanly and in moderate to good yield.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 171
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1727-1734 
    ISSN: 1434-193X
    Schlagwort(e): Self-assembly ; Vapor-pressure osmometry ; Resorcin[4]arenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Resorcin[4]arene tetracarboxylic acids 5,6 (A) and resorcin[4]arene tetrapyridines 2,3 (P) self-assemble in chloroform solution to form stable heterotopic AP dimers. Data from NMR titration and dilution experiments, as well as from vapor-pressure osmometry (VPO), indicate that the AP dimer is formed with an association constant greater than 107 M-1. Solid-solution extraction experiments are indicative of the formation of a 2:1 trimer (A2P), while self-associated homotopic species (A2 and A3) can be detected by NMR and VPO. Analysis of the heterotopic noncovalent assembly process over a range of compositions shows that these other species are much less stable than the AP heterodimer, which is the exclusive species at an A/P concentration ratio of 1:1 (〉 99.7% of the total at 10 mM).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 172
    ISSN: 1434-193X
    Schlagwort(e): Sulfoxides ; β-Amino sulfones ; Mannich type reaction ; Lithium perchlorate ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The LiClO4-mediated one-pot reaction of aldehydes with (trimethylsilyl)dialkyl amines and the lithium salt of sulfoxides or sulfones, affords the corresponding β-(dialkylamino) sulfoxides and β-(dialkylamino) sulfones in high yields. The aminosulfoxidation reaction of aliphatic or aromatic aldehydes lacks diastereoselectivity, but the diastereomeric sulfoxides can be separated by HPLC or column chromatography for further use.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 173
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1741-1744 
    ISSN: 1434-193X
    Schlagwort(e): Bridged pyranose derivatives ; Ring enlargement ; Carbenes ; Glycosides ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Addition of dichlorocarbene to the glycal (±±)-2 followed by cyclopropyl-allyl rearrangement leads to the chloro-2H-pyran (±±)-4. Oxidation of (±±)-4 and reduction of the obtained hydroxypyranone (±±)-5 gave the methyl pyranoside (±±)-6. The relative configuration of (±±)-6 was established by X-ray structural analysis of the corresponding acetate (±±)-7. The synthesis of the optically active starting materials (+)-2 and (-)-2 is also reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 174
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1745-1758 
    ISSN: 1434-193X
    Schlagwort(e): CMP-Neu5Ac analogues ; Enzyme inhibitors ; Substrate analogues ; Transition state analogues ; Transferases ; Carbohydrates ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Quinic acid was transformed into phosphitamides 16, 25, and 36, which could be readily linked to 5′-O-unprotected cytidine derivative 17. Ensuing oxidation of the obtained phosphite triesters with tBuO2H and hydrogenolytic de-O-benzylation furnished the corresponding phosphate diesters 18, 26, and 38. Base catalyzed removal of acetyl protecting groups, and methyl ester hydrolysis furnished CMP-Neu5Ac analogues 1d, 1e, and 2. Quinic acid was also transformed into 1,2-unsaturated diallyl α-hydroxymethyl-phosphate derivatives (R)- and (S)-46, which on reaction with cytidine phosphitamide 47 afforded the phosphite triesters. Subsequent oxidation with tBuO2H and then treatment with NEt3 gave phosphate diester derivatives (R)- and (S)-48. Deallylation, acetyl group removal, and methyl ester hydrolysis furnished (R)- and (S)-3, respectively. Treatment of (R)- and (S)-48 with DBU as a base led to acetic acid elimination, thus yielding, after de-O-allylation, acetyl group cleavage, and ester hydrolysis, diene derivative (E)-4. Donor substrate analogues 1d and 1e exhibited good α(2-6)-sialyltransferase inhibition (Ki: 2.0·10-4 and 2.0·10-5 M). However, transition state analogues (R)-, and particularly (S)-3 showed excellent inhibition properties (Ki: 1.6·10-6 and 2.7·10-7 M).
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 175
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1759-1765 
    ISSN: 1434-193X
    Schlagwort(e): Cyclitols ; Aminocyclitols ; Glycosidase inhibitors ; α-Mannosidase inhibitors ; Deoxygenation ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Three deoxy derivatives 2-4 of the α-mannosidase inhibitor mannostatin A (1) were synthesized, and their inhibition of Jack bean α-mannosidase was evaluated in order to elucidate the roles of each of the three hydroxyl groups of the inhibitor. The 1- and 2-deoxy derivatives 2 and 3 retained some inhibitory activity, although reduced by a factor of about 100 relative to the parent, whereas it was completely lost with the 3-deoxy derivative 4. Structure and activity relationships are discussed in the light of these findings.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 176
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1767-1772 
    ISSN: 1434-193X
    Schlagwort(e): Circular dichroism ; Conformation analysis ; s-Triazines ; Chiral auxiliaries ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---CD data of the optically pure 2-[(R)-1-(9-anthryl)ethylamino]-4-chloro-6-[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2[(R)-1-(9-anthryl)ethylamino]-4,6-bis[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2,4-bis[(R)-1-(9-anthryl)ethylamino]-6-chloro-1,3,5-triazine are presented. The analysis of the CD spectra by means of the nonempirical DeVoe approach has afforded the complete conformational characterisation of the three s-triazine derivatives, allowing us to establish how the conformation of these derivatives depends on the nature of the substituent 1-arylethylamino groups.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 177
    ISSN: 1434-193X
    Schlagwort(e): Cycloadditions ; Carbenes ; Nitrones ; Nitrilimines ; Pyrazolines ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The reaction of tert-butylalkynyl chromium Fischer carbene complex 1 with nitrones 2 affords β-enamino-ketoaldehydes 4 by the light-promoted rearrangement of the corresponding [3+2] cycloadduct carbene complexes 3. On the other hand, [3+2] cycloaddition of chiral nonracemic Fischer alkenyl carbene complexes 19 with nitrilimines 10 yields enantiomerically pure Δ2-pyrazolines with high regio- and diastereoselectivity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 178
    ISSN: 1434-193X
    Schlagwort(e): Asymmetric synthesis ; Zinc ; Transition structures ; QM/MM computations ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Trimethylsilyl substitutions of the fenchyl alcohols [(1R,2R,4S)-exo-(2-Ar)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol, Ar = 2-methoxyphenyl (1) and Ar = 2-(dimethylaminomethyl)phenyl (2)] yield the chiral ligands 3 [Ar = 2-methoxy-3-(trimethylsilyl)phenyl] and 4 [Ar = 2-(dimethylaminomethyl)3-(trimethylsilyl)phenyl]. Increased reactivities and enantioselectivities in diethylzinc additions to benzaldehyde are obtained from 3 (63% ee R) and 4 (93% ee S), relative to 1 (26% ee S) and 2 (73% ee S). X-ray crystal structures of 3 and of its methylzinc complex 3-Zn reveal out-of-plane bending of the methoxy groups as major geometrical consequences of the trimethylsilyl substitutions. Analyses of QM/MM ONIOM μ-O transition-structure models for 1, 2, 3, and 4 show that trimethylsilyl-induced distortions of methoxy and of dimethylaminomethyl groups explain the observed increased enantioselectivities.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 179
    ISSN: 1434-193X
    Schlagwort(e): Palladium ; exo-π-Allylpalladium complexes ; Allylic alkylation ; Spiro compounds ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The palladium(0)-catalyzed alkylation of 2,3-bis(acetoxymethyl)bicyclo[2.2.1]hepta-2,5-diene 1 with malonate-type enolates as nucleophiles is investigated. A monoalkylated product is formed first, and undergoes (depending on the nucleophile used) a second intramolecular reaction leading to spirocyclopropane-annulated bicyclo[2.2.1]heptene derivatives 5. The formation of endo spirobicyclic cyclopropanes adducts as major isomer is rationalized by assuming formation of an intermediate exo-(π-allyl)palladium complex.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 180
    ISSN: 1434-193X
    Schlagwort(e): Ketones ; Reductions ; Micelles ; Cobalt ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Operationally simple and environmentally benign procedures have been developed to selectively reduce different α,β-unsaturated ketones, 4,4-dimethylcyclohex-2-ene-1-one (1), isophorone (2), benzylideneacetone (3), chalcone (4) by NaBH4 or by the system NaBH4 + CoCl2. Alternative reaction media to the extensively used MeOH have been explored, and new procedures take advantage of the acceleration and chemoselectivity induced by water or by aqueous micellar solutions. It was possible to selectively and quantitatively afford pure products of 1,2 and of 1,4 reduction as well as the totally reduced compounds (yield and selectivity 〉 90%) by simple changes in the experimental conditions.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 181
    ISSN: 1434-193X
    Schlagwort(e): C-Glycosides ; Conformation analysis ; Molecular dynamics ; Selectins ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The conformational behavior of the C-glycosyl analogue of sialyl-α-(2→3)-galactose, synthesized as a glycosidase inhibitor, has been studied using a combination of NMR spectroscopy (J and NOE data) and molecular dynamics calculations. The obtained results show that the population distribution of conformers with respect to the orientation about the pseudo-glycosidic linkages is mainly controlled by steric interactions. This is in contrast to findings made for O-glycosides. In these natural compounds, the conformational behavior about the glycosidic linkage Φ is mainly governed by the exo-anomeric effect.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 182
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1815-1820 
    ISSN: 1434-193X
    Schlagwort(e): Asymmetric synthesis ; Palladium-catalysed couplings ; Palladacycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Chiral C2-symmetric N-benzylazetidines have been conveniently prepared from optically pure anti-1,3-diols without loss of enantiomeric purity. N-Debenzylation led to the corresponding N-unsubstituted azetidines, which were then subjected to palladium-catalysed coupling reactions with aryl bromides to afford chiral N-arylazetidines. (R,R)-N-Benzyl-2,4-dimethylazetidine has been employed in the synthesis of a new cyclopalladated complex, which can be used, for instance, as a chiral recognition agent for phosphorus ligands.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 183
    ISSN: 1434-193X
    Schlagwort(e): Cyclizations ; Spiro compounds ; Nucleosides ; Isomerizations ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Syntheses of the spiro nucleosides 2′-deoxyhydantocidin 3a and its 1′-epimer 3b are described. The newly developed route involves a Horner-Wadsworth-Emmons condensation of the phosphonate 16 with the erythrose derivative 15 affording a mixture of six isomers which was fully assigned by NMR spectroscopy. The mixture was directly converted into the final compounds in an efficient base-catalyzed cyclization reaction. A base-catalyzed interconversion between the two isomers was observed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 184
    ISSN: 1434-193X
    Schlagwort(e): Benzodiazepines ; Heterocycles ; Azeto[1,2-a]-1,5-benzodiazepines ; Cyclizations ; Cycloadditions ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The reaction of o-phenylenediamine (4) with one, two or three equivalents of p-substituted 3-dimethylaminopropiophenone hydrochlorides 5a-e was studied. 4-Aryl-2,3-dihydro-1H-1,5-benzodiazepine derivatives 6a-e were obtained in good yields, along with the 1:2-adducts 7c-e and the unexpected 1:3-adducts rac-8c-e. The type of adduct formed is determined by the molar ratio of the reactants 4 and 5 and by the nature of the substituent in the para position of the propiophenone 5.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 185
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1965-1971 
    ISSN: 1434-193X
    Schlagwort(e): Cup-shaped PAHs ; Host-guest compounds ; Host-guest chemistry ; Cyclizations ; Semiempirical calculations ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Cyclotrimerisation of benzo-polycyclic bromostannylalkenes 8a-d with Cu(NO3)2·3H2O in THF affords benzotri(benzonorbornadienes) 3a-d as a mixture of the syn and anti isomers. The ratio of syn to anti is close to the 1:3 statistical value in most cases (i.e. in cyclotrimers 3a,b,d), but highly in favour of the anti isomer in 3c, where steric hindrance by the methoxy groups plays an important role in the stereochemistry of the cyclotrimerisation. The substrates for the cyclotrimerisation, i.e. the bromostannyl alkenes 8a-d, were prepared from bromoalkenes 7a-d by treatment with base (LDA) and quenching with trimethyltin chloride. In turn, bromoalkenes 7a-d were prepared from alkenes 5a-d by radical bromination-elimination. The reaction conditions used were designed to minimise Wagner-Meerwein rearrangements that would lead to unwanted bromo isomers. The cup-shaped syn cyclotrimers 3a-d exhibit high electron density within the cavity as determined by AM1 semiempirical calculations of their electrostatic potential surfaces and are valuable substrates for supramolecular chemistry. As an example, it is shown that fullerene C60 is drawn into solution in acetonitrile by complexation with both the syn and anti trimer of benzonorbornadiene 3a.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 186
    ISSN: 1434-193X
    Schlagwort(e): Carbene complexes ; Enamines ; Metallatrienes ; Cyclopentadienes ; Dihydropyrroles ; spiro-Tetrahydropyrroles ; Iminium carbonylmetalates ; Dimetallapolyenes ; Tungsten ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Reactions of the [(1-alkynyl)carbene]tungsten complex (CO)5W=C(OEt)C≡CPh (1) with 1-aminocyclohexenes 2a-c and 7a-c afford different types of products depending on the amino substituents and the reaction conditions. (4-Aminocyclobutenyl)carbene complexes B have been shown to be generated in the first reaction step through a [2+2] cycloaddition. These are key intermediates and afford cross-conjugated tungstatrienes E, (conjugated) 1-tungsta-1,3,5-hexatrienes G, or (non-conjugated) 1-tungsta-1,3,6-heptatrienes F by following competing reaction pathways. Cross-conjugated 1-tungstatrienes 3 have been isolated in 52-74% yield by performing the reactions of 1-aminobenzocyclohexenes 2a-c with compound 1 in pentane. In dichloromethane instead of pentane, (conjugated) 1-tungsta-1,3,5-hexatrienes 4 are obtained, which subse-quently undergo fragmentation to give cyclopentadienes 6 (by π-cyclization) and dihydropyrroles (by α-cyclization) in a molar ratio dependent on the nature of the amino substituents. (Non-conjugated) 1-tungsta-1,3,6-heptatrienes 10 are generated upon reaction of 1-aminocyclohexenes 7a-c with compounds 1, which are transformed into cyclopentadienes 12 via conjugated 1-tungsta-1,3,5-hexatrienes 9 as intermediates. Reactions of 1-tungsta-1,3,6-heptatrienes 10 with the (1-alkynyl)carbene complex 1 afford dinuclear compounds 14, which subsequently yield indenes 15 (by two successive π-cyclization steps) and spiro-tetrahydropyrroles 16 (by both a π-cyclization and an α-cyclization step), depending on the steric bulk of the amino substituent.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 187
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 99-104 
    ISSN: 1434-193X
    Schlagwort(e): Allyl alcohols ; Organocerium reagents ; Alkenes ; Addition reactions ; Cerium ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Alkylcerium reagents add to the multiple bonds of allyl and propargyl alcohols in good yields and under mild conditions. The double bond can be reduced with lithium aluminum hydride in the presence of cerium trichloride. The regiochemistry of the attack depends on electronic factors.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 188
    ISSN: 1434-193X
    Schlagwort(e): Amidines ; Chiral bases ; N-Acyliminium ions ; Enantioselective catalysis ; Chiral pool ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The synthesis of four enantiopure hydroxyamidines is described. One amidine was obtained from (S)-pyroglutamic acid. Its key step involved the addition of phenylmagnesium bromide to the corresponding ester, affording the tertiary alcohol without detectable racemization. The second amidine was obtained by coupling of an (S)-malic acid derived N-acyliminium ion with β-naphthol. The other amidines were obtained from an (S)-serine-derived imide which was reduced to two diastereomeric lactams that were eventually transformed into the corresponding amidines.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 189
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 155-163 
    ISSN: 1434-193X
    Schlagwort(e): Macrocycles ; Cyclizations ; Strained compounds ; Ketophosphonate ; Iodoalkyne ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Two strategies have been explored to build the highly strained eleven-membered ring 2, a potential precursor for the biosynthetic key intermediate of the protoilludane family: an intramolecular Horner-Wadsworth-Emmons olefination and an intramolecular Nozaki-Hiyama-Kishi type-ring closure.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
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  • 190
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 165-170 
    ISSN: 1434-193X
    Schlagwort(e): Neutral anion receptor ; Hydrogen bonds ; Urea moieties ; Donor-acceptor systems ; Macrocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The synthesis of macrocyclic and acyclic cleft-like anion receptors in which four hydrogen bond donating urea moieties are present in a preorganized fashion is described. NMR spectroscopy shows the complex formation with H2PO4- and Cl -. Cleft-like receptors bind H2PO4- in a 2:1 guest-host stoichiometry (Ka = 107M-2) in DMSO, whereas Cl - is bound in a 1:1 stoichiometry (Ka = 103M-1). The macrocyclic receptors form a 1:1 complex with H2PO4- (Ka = 103M-1 in DMSO) with a 100-fold selectivity for H2PO4- over Cl -.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 191
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 193-198 
    ISSN: 1434-193X
    Schlagwort(e): Nucleophilic substitutions ; Azulenes ; Hydroxylation ; Amination ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Hydroxylation of azulenes with tert-butylhydroperoxide proceeds efficiently at the 6-position when the former contain electron-withdrawing substituents in the five-membered ring. Similarly, VNS amination of azulenes proceeds with 4-amino-1,2,4-triazole; its anion, being an active nucleophile, also reacts with unsubstituted azulene. A variety of transformations of 6-hydroxyazulenes, such as substitution of the corresponding sulfonates with nitrogen, oxygen, sulfur, carbon nucleophiles and halogens, and the Claisen rearrangement of allylic ethers, is reported.
    Materialart: Digitale Medien
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  • 192
    ISSN: 1434-193X
    Schlagwort(e): Heterocycles ; Carbohydrates ; Imidazolidines ; Oxazolidines ; Spiro compounds ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Prochiral 1,3-dihydroxyacetone forms racemic oxazolidine- and oxazoline-type spiro[4.4]nonanes upon reactions with potassium (thio)cyanate and cyanamide. In contrast, 1,3-diaminoacetone yields only the corresponding spiro-bisimidazolidinethione under similar conditions together with monocyclic by-products, but the spiro-bisimidazolidinone is accessible by reaction of 1,3-dichloroacetone with urea. The resolution of the racemic spiro-bisoxazolidinethione 2a was achieved by using brucine as the resolving agent.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 193
    ISSN: 1434-193X
    Schlagwort(e): Homogeneous catalysis ; Palladium ; Acetoxylation ; Acryloxylation ; Addition reactions ; Cyclooctadiene ; Cyclooct-4-enone ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Palladium-catalyzed acryloxylation of several cycloalkenes in the presence of the Pd(OAc)2/p-benzoquinone/MnO2 catalytic system is reported. This oxidation reaction yields allylic acrylates as the sole products through the intermediacy of an η3-allyl complex. However, with 1,5-cyclooctadiene (3), cyclooct-4-enone (4) is the major reaction product. Its formation results from oxidation, which is also observed in the palladium-catalyzed acetoxylation of 3. It has been shown that this is the result of a 1,2-trans addition (acryloxy-palladation), followed by a β-hydride elimination, which yields an enol acrylate or acetate. A second Markovnikov-oriented 1,2-trans-acryloxy-palladation on the latter yields a palladium complex, rearrangement of which gives 4.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 194
    ISSN: 1434-193X
    Schlagwort(e): Amino acids ; coupling ; N-Substituted amide ; Cyclizations ; Cyclic dipeptides ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A short synthesis of new, functionalized seven-membered ring cyclic dipeptides is described. After the coupling of N-protected β-amino acids to N-substituted α-amino tert-butyl esters, the protective groups of the terminal functions were removed and the cyclization took place diastereoselectively in the presence of the coupling agent BOP. Amide substitution was found to be effective in promoting the cyclization of linear dipeptides.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 195
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 275-280 
    ISSN: 1434-193X
    Schlagwort(e): Radical reactions ; Substituent effects ; Nitrogen heterocycles ; Dihydropyridines ; Pyrrolines ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A set of allene-tethered benzoyloximes (5) has been treated with nBu3SnH. Depending on their substitution pattern, a wide range of compounds has been obtained. If the stannyl radical adds on the allene, the C-centred radical thus formed undergoes either a 5-exo ring closure to give the cyclopentene derivatives 7 or a 6-endo ring closure onto the N atom to give the dihydropyridines 8. If the stannyl radical adds on the benzoyl moiety, an iminyl radical is formed which leads to the 3H-pyrroles 9 and the alkylidene-pyrrolines 10. Steric effects as well as polar effects are the factors governing the reaction course.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99373_s.pdf or from the author.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 196
    ISSN: 1434-193X
    Schlagwort(e): Antibiotics ; Configuration determination ; Heterocycles ; Hongoquercin A ; Terpenoids ; Total synthesis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---(±)-Hongoquercin A (1), the racemate of an antibacterial fungal metabolite, has been synthesized starting from geranylacetone (2) and ethyl orsellinate (ethyl 2,4-dihydroxy-6-methylbenzoate, 5). The structure (±)-1 has been confirmed by X-ray analysis of its ethyl ester (±)-10. Synthesis of the naturally occurring (+)-hongoquercin A from (-)-sclareol (11) established its configuration as depicted in 1.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 197
    ISSN: 1434-193X
    Schlagwort(e): Carbohydrates ; Amino sugars ; Protecting groups ; Glycosylations ; Trichloroacetimidates ; Oligosaccharides ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The N-DMM-Protected lactosamine derivative 2 was readily transformed into the corresponding glycosyl donor 4 and into acceptor 5. A TMSOTf-catalyzed glycosidation afforded the derived tetrasaccharide 6 which led to glycosyl donor 9. Reaction of 9 with lactose derivative 10 as acceptor gave the desired hexasaccharide 11. Cleavage of all protective groups and N-acetylation afforded the target molecule 1b (lacto-N-neohexaose). Glycosylation of acceptor 10 with donor 4 furnished tetrasaccharide 16 which, employing standard procedures, gave acceptor 18. Glycosylation of 18 with donor 9 furnished, under standard conditions, octasaccharide 19. Cleavage of all protective groups and N-acetylation afforded the target molecule 1c (lacto-N-neooctaose). Both 1b and 1c were obtained in good overall yields.
    Materialart: Digitale Medien
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  • 198
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 349-356 
    ISSN: 1434-193X
    Schlagwort(e): Sharpless asymmetric dihydroxylation ; Asimilobin ; Tetrahydrofuran ring ; Wittig reactions ; Annonaceous acetogenins ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The most efficient method for the synthesis of the trans/threo/trans-bis(tetrahydrofuran) (THF) ring unit was established, and the first total synthesis of (-)-asimilobin and its diastereomer was then accomplished in twelve and fourteen steps, respectively, from trans-1,5,9-decatriene, by a convergent route with a Wittig reaction as the key step. By virtue of these synthetic results, the absolute configuration of the bis(THF) unit in naturally occurring asimilobin should be corrected.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 199
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 381-385 
    ISSN: 1434-193X
    Schlagwort(e): Enynes ; Macrocycles ; Coordination chemistry ; Crown compounds ; Radicals ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The complex molecular structure and interesting activation mechanisms of naturally occurring enediynes have inspired the synthesis of a variety of simpler model systems to mimic their properties. While in most model compounds nucleophilic attack, isomerization or bioreduction are used to activate the unsaturated system for diradical cyclization, some attempts have been made to employ metal-ion coordination for this purpose. Significant enhancement of the thermal reactivity has been achieved by metal-ion induced conformational and electronic changes of suitably substituted enediynes, such as 1, 5, 6, 17 and 18. Enediyne activation by stoichiometric or catalytic formation of vinylidene complexes, such as 22, from terminal alkynes has also been investigated. This paper summarizes recent results pursuing the activation of enediyne diradical cyclization by metal ions.
    Materialart: Digitale Medien
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  • 200
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 419-423 
    ISSN: 1434-193X
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The first enantioselective synthesis of enantiomerically pure (-)-wine lactone, (-)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an organocopper compound and by enolate alkylation gave lactone (-)-1a in 43% overall yield from (+)-7.
    Materialart: Digitale Medien
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