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  • 1
    Electronic Resource
    Electronic Resource
    The activation state of nitrate reductase is not always correlated with total nitrate reductase activity in leaves (1999)
    Springer
    Planta 209 (1999), S. 462-468 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Activation state (nitrate reductase) ; Hordeum (nitrate reductase) ; Nitrate reductase ; Nitrate supply ; Phosphate deficiency ; Signal metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The relation between nitrate reductase (NR; EC 1.6.6.1) activity, activation state and NR protein in leaves of barley (Hordeum vulgare L.) seedlings was investigated. Maximum NR activity (NRAmax) and NR protein content (Western blotting) were modified by growing plants hydroponically at low (0.3 mM) or high (10 mM) nitrate supply. In addition, plants were kept under short-day (8 h light/16 h dark) or long-day (16 h light/8 h dark) conditions in order to manipulate the concentration of nitrate stored in the leaves during the dark phase, and the concentrations of sugars and amino acids accumulated during the light phase, which are potential signalling compounds. Plants were also grown under phosphate deficiency in order to modify their glucose-6-phosphate content. In high-nitrate/long-day conditions, NRAmax and NR protein were almost constant during the whole light period. Low-nitrate/long-day plants had only about 30% of the NRAmax and NR protein of high-nitrate plants. In low-nitrate/long-day plants, NRAmax and NR protein decreased strongly during the second half of the light phase. The decrease was preceded by a strong decrease in the leaf nitrate content. Short daylength generally led to higher nitrate concentrations in leaves. Under short-day/low-nitrate conditions, NRAmax was slightly higher than under long-day conditions and remained almost constant during the day. This correlated with maintenance of higher nitrate concentrations during the short light period. The NR activation state in the light was very similar in high-nitrate and low-nitrate plants, but dark inactivation was twice as high in the high-nitrate plants. Thus, the low NRAmax in low-nitrate/long-day plants was slightly compensated by a higher activation state of NR. Such a partial compensation of a low NRmax by a higher dark activation state was not observed with phosphate-depleted plants. Total leaf concentrations of sugars, of glutamine and glutamate and of glucose-6-phosphate did not correlate with the NR activation state nor with NRAmax.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050749
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  • 2
    Electronic Resource
    Electronic Resource
    Increased nitrate reductase activity in leaf tissue after application of the fungicide Kresoxim-methyl (1999)
    Springer
    Planta 207 (1999), S. 442-448 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Nitrate reductase ; Respiration inhibitors ; Spinacia ; Strobilurin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Spinach (Spinacia oleracea L.) leaf discs floating on buffer solution were treated with Kresoxim-methyl (KROM), an inhibitor of respiratory electron transport. In the leaf tissue, actual and maximal nitrate reductase (NR) activities, nitrite content and ATP levels were determined. In darkened leaf discs incubated without KROM (control) actual NR activity decreased to 20% after 6 h in the dark. Treatment with 10 μg ml−1 (corresponding to 32 μM) KROM totally prevented inactivation of NR in the dark and also diminished NR-protein degradation during prolonged darkness. Due to restricted nitrite reduction in darkened leaf tissues, nitrite accumulated in KROM-treated discs. Inhibition of respiration decreased ATP and increased AMP levels in KROM-treated discs. In illuminated leaf discs, NR was highly activated to 65%. Nevertheless, KROM-treatment caused an additional activation of NR (activation state 76%) in the light. Possible side-effects of KROM on nitrite reduction and photosynthesis were also checked in the leaf-disc system. Neither nitrite reduction nor photosynthesis were altered in KROM-treated discs. The extent of KROM-induced activation of NR was dependent on the applied concentration and on the pH of the external medium. The highest activation of NR was achieved at an external pH of 4.8, confirming previous results (Kaiser and Brendle-Behnisch, 1995, Planta 196: 1–6) that cytosolic acidification might play an important role in the modulation of NR activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050503
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  • 3
    Electronic Resource
    Electronic Resource
    Die idiopathische Osteolyse nach Gorham-Stout – Eine lokale osteoklastäre Hyperaktivität? (1999)
    Springer
    Der Pathologe 20 (1999), S. 177-182 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Massive idiopathische Osteolyse ; Gorham-Stout-Syndrom ; Hüftgelenk ; Pathogenese ; Antiresorptive Therapie ; Key words Massive idiopathic osteolysis ; Gorham-Stout-Syndrome ; Hip joint ; Pathogenesis ; Antiresorptive therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary One rare case of so-called massive idiopathic osteolysis Gorham-Stout is presented. In a 77-year-old female patient the whole right femoral head and neck of femur was resorbed within 2.5 month following trauma. As a histologic cause for the osteolysis, a marked stimulation of osteoclasts on the spongiosa, especially intracortically, was observed. The course and the clinical findings are described, and the pathogenesis and treatment are discussed in comparison with the present literature. The results suggest that an early antiresorptive therapy (calcitonin, bisphosphonates) could stop the progressive osteolytic changes.
    Notes: Zusammenfassung Berichtet wird über den seltenen Fall einer sog. massiven idiopathischen Osteolyse nach Gorham-Stout. Posttraumatisch kam es bei einer 77jährigen Patientin innerhalb von 2,5 Monaten zur Resorption des gesamten rechten Hüftkopfs und Schenkelhalses. Als Ursache für die Osteolyse konnte histologisch eine ausgeprägte Stimulation von Osteoklasten an der Spongiosa und v. a. intrakortikal erkannt werden. Das Krankheitsbild wird beschrieben, die Pathogenese und Therapie im Vergleich mit der vorliegenden Literatur diskutiert. Die Ergebnisse weisen darauf hin, daß durch die frühzeitige Gabe von antiresorptiven Substanzen (Calcitonin, Bisphosphonate) progressive osteolytische Veränderungen therapiert werden könnten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050341
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  • 4
    Electronic Resource
    Electronic Resource
    Das Chondromyxoidfibrom Morphologische Variationsbreite, Lokalisation, Häufigkeit, radiologische Kriterien und Differentialdiagnose (1999)
    Springer
    Der Pathologe 20 (1999), S. 224-229 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Knochentumoren ; Chondromyxoidfibrom ; Histologie ; Key words Bone tumors ; Chondromyxoid fibroma ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Chondromyxoid fibroma is a rare benign bone tumor, accounting for less than 1% of all bone tumors. The peak age incidence is the second and third decade of life. Chondromyxoid fibrom occurs in the metaphyseal parts of the major tubular bones, predominantly of the lower extremity. Roentgenograms show, in most cases, a well-demarcated radiolucent lesion. The classic histological feature of a chondromyxoid fibroma is stellate or spindle-shaped cells arranged in lobules in a myxoid or chondroid background. Analysis of 40 chondromyxoid fibromas demonstrates the morphological variation of this tumor. Cases were examined for age distribution, localization, and radiological and histological features. In 85% we found the typical histomorphological pattern. Recurrence rate was 12.5%. In four cases the appearance was uncharacteristic and differentiation from other tumors such as chondroblastoma or chondrosarcoma was quite difficult. By adhering to strict histomorphological criteria, definite diagnosis of chondromyxoid fibroma can be made in most cases.
    Notes: Zusammenfassung Das Chondromyxoidfibrom ist ein seltener gutartiger Knochentumor. Seine Häufigkeit beträgt weniger als 1% aller primären Knochentumoren. Das Hauptmanifestationsalter ist die 2. und 3. Lebensdekade. Der Tumor ist überwiegend in der Metaphyse langer Röhrenknochen lokalisiert, insbesondere der unteren Extremität. Radiologisch stellt er in den meisten Fällen eine scharf begrenzte, osteolytische Läsion dar. Histologisch zeigt er einen lobulären Aufbau mit einer chondroiden oder myxoiden Grundmatrix. Die Zellen sind spindelig bis sternförmig. Anhand von 40 Chondromyxoidfibromen soll die morphologische Variationsbreite dieser Tumorentität dargestellt werden. Die Fälle wurden nach Altersverteilung, Lokalisation und radiologischen sowie pathomorphologischen Kriterien untersucht. In 85% der untersuchten Fälle fanden sich die typischen histomorphologischen Kriterien des Chondromyxoidfibroms. Bei 5 Patienten (12,5%) kam es zu einem Rezidiv. 4 Fälle zeigten ein uncharakteristisches Bild und waren nur bedingt von anderen Knochentumoren (Chondroblastom, Chondrosarkom) abzugrenzen. Bei Beachtung strenger histomorphologischer Kriterien aber kann die Diagnose Chondromyxoidfibrom in den meisten Fällen sicher gestellt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050349
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  • 5
    Electronic Resource
    Electronic Resource
    Delayed reverberation through time windows as a key to cerebellar function (1999)
    Springer
    Biological cybernetics 81 (1999), S. 373-380 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. We present a functional model of the cerebellum comprising cerebellar cortex, inferior olive, deep cerebellar nuclei, and brain stem nuclei. The discerning feature of the model being time coding, we consistently describe the system in terms of postsynaptic potentials, synchronous action potentials, and propagation delays. We show by means of detailed single-neuron modeling that (i) Golgi cells can fulfill a gating task in that they form short and well-defined time windows within which granule cells can reach firing threshold, thus organizing neuronal activity in discrete `time slices', and that (ii) rebound firing in cerebellar nuclei cells is a robust mechanism leading to a delayed reverberation of Purkinje cell activity through cerebellar-reticular projections back to the cerebellar cortex. Computer simulations of the whole cerebellar network consisting of several thousand neurons reveal that reverberation in conjunction with long-term plasticity at the parallel fiber-Purkinje cell synapses enables the system to learn, store, and recall spatio-temporal patterns of neuronal activity. Climbing fiber spikes act both as a synchronization and as a teacher signal, not as an error signal. They are due to intrinsic oscillatory properties of inferior olivary neurons and to delayed reverberation within the network. In addition to clear experimental predictions the present theory sheds new light on a number of experimental observation such as the synchronicity of climbing fiber spikes and provides a novel explanation of how the cerebellum solves timing tasks on a time scale of several hundreds of milliseconds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050569
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  • 6
    Electronic Resource
    Electronic Resource
    Keck mid-ir High-Resolution Imaging of arp 220 (1999)
    Springer
    Astrophysics and space science 266 (1999), S. 109-111 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002697514481
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  • 7
    Electronic Resource
    Electronic Resource
    20q13.2 Amplification in intraductal hyperplasia adjacent to in situ and invasive ductal carcinoma of the breast (1999)
    Springer
    Virchows Archiv 435 (1999), S. 469-472 
    Details
    ISSN: 1432-2307
    Keywords: Key words Breast cancer ; Carcinoma in situ ; Hyperplasia ; Fluorescence in situ hybridization ; Chromosome 20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The 20q13 region harboring recently described putative oncogenes is frequently amplified in invasive ductal carcinoma (IDC). The aim of this study was to examine the 20q13 copy number in intraduct hyperplasia (IH), atypical duct hyperplasia (ADH), and ductal carcinoma in situ (DCIS) adjacent to IDC. In 5 patients, comparative genomic hybridization (CGH) after laser microdissection revealed 20q13 amplification in four of five cases of IH, in all of three cases of IH with atypia, all five of DCIS, and all five of IDC. Fluorescence in situ hybridization (FISH) confirmed the amplification at 20q13.2 in IH in the two specimens analyzed. The amplification rate, however, was higher in DCIS and IDC. In phenotypically normal ductal epithelium normal values were found for 20q13 copy number by FISH (n=2) and CGH (n=5). Although the number of cases presented here is small, our results suggest that mutations in the 20q13.2 region in IH may be associated with accelerated proliferation and hyperplasia of the ductal epithelium. Progression to DCIS and ICD is accompanied by a further increase in the 20q13.2 copy number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050429
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  • 8
    Electronic Resource
    Electronic Resource
    Muons on request (MORE): combining advantages of continuous and pulsed muon beams (1999)
    Springer
    Hyperfine interactions 120-121 (1999), S. 575-578 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A technique has been tested for the first time which combines the advantages of continuous and pulsed muon beams, namely high time resolution and low background in time-differential μSR experiments. In addition, the method allows the muon beam to be split and two μSR experiments run simultaneously at full intensity without any interference between the instruments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017046817431
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  • 9
    Electronic Resource
    Electronic Resource
    Seltene Tumoren der Bauchhöhle (1999)
    Springer
    Der Onkologe 5 (1999), S. 948-955 
    Details
    ISSN: 1433-0415
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Retroperitoneale Sarkome gehören mit einer Häufigkeit zwischen 0,1 und 0,2% aller diagnostizierten Tumoren zu den seltenen Tumoren. Der nur nach ventral und dorsal gut begrenzte Retroperitonealraum ermöglicht Sarkomen lange Zeit ein fast uneingeschränktes Wachstum. Dementsprechend verläuft die klinische Symptomatik sehr lange unspezifisch und unerkannt. Des öfteren werden diese Tumoren erst durch sekundäre Komplikationen am Gastrointestinaltrakt oder Retroperitoneum diagnostiziert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007610050454
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