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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2661-2664 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The experimental and numerical study of the radiation pattern around a point source antenna immersed in a hot drifting magnetoplasma (the so-called resonance cones) at frequencies lying inside the upper branch shows that the electron drift velocity can be detected through the determination of the cone angles shifted downstream by the Doppler effect. The easiest measurement is performed at the plasma frequency. The drift velocity is also compared to the value given by the electron saturation current of a rotatable plane Langmuir probe.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Quantitative Spectroscopy and Radiative Transfer 41 (1989), S. 69-78 
    ISSN: 0022-4073
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Advances in Space Research 12 (1992), S. 259-262 
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Advances in Space Research 12 (1992), S. 263-266 
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Urologe 37 (1998), S. 386-394 
    ISSN: 1433-0563
    Keywords: Key words Telomerase • Inhibition of telomerase • Gene therapy • Urologic tumors ; Schlüsselwörter Telomerase • Inhibition der Telomerase • Gentherapie • Urologische Tumoren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Expression des Ribonukleoproteins Telomerase wird seit kurzem als möglicher neuer Mechanismus in der Tumorentstehung diskutiert. Durch seine Aktivierung werden die Chromosomenenden, sog. Telomere, vor einer physiologischen Verkürzung und einer damit einhergehenden chromosomalen Instabilität geschützt. Die Telomerase exprimierenden Zellklone werden immortal. In einer anfänglichen Euphorie durch erste Studien, die in einem hohen Prozentsatz Telomeraseaktivität in Tumoren, nicht aber in gesunden, normalen Geweben, nachgewiesen haben, weckte die Telomerase auch Interesse und Hoffnungen im Hinblick auf eine mögliche therapeutische Anwendbarkeit. Nach aktueller Vorstellung soll durch die Inaktivierung der Telomerase der Tod immortaler Zellen eingeleitet werden. Sollte es sich bei der Telomeraseaktivierung um ein tumorspezifisches Merkmal handeln, ergäben sich vielversprechende (gen)therapeutische Ansätze mit hoher Effektivität und wahrscheinlich geringen Nebenwirkungen. Neuere Untersuchungen beschreiben mittlerweile allerdings auch Telomeraseaktivitäten in normalen Geweben sowie in nichtneoplastischen, hyperproliferativen Gewebeveränderungen. Die aus diesen Ergebnissen resultierenden Fragen, nämlich ob es sich bei der Telomeraseaktivität um ein tumorspezifisches oder um ein mit (physiologischer oder pathologischer) Hyperproliferation assoziiertes Phänomen handelt, müssen definitiv geklärt werden.
    Notes: Summary Recent reports have indicated the ribonucleoprotein enzyme telomerase to play an important role in tumorigenesis. Activation of this enzyme is known to prevent progressive shortening of the end of the chromosomes, or telomeres, and hence to be critical in maintaining chromosomal integrity. The telomerase expressing cells require immortality. Supported by recent findings which suggest that telomerase activity is expressed in virtually all cancers but not in normal tissues, except those of the germline, hope grew up toward a potentially important new therapeutic target in the fight against cancer. An emerging hypothesis is that the inactivation of telomerase results in the death of immortal cells. If telomerase activation represents a tumor-specific feature, (gene) therapeutic applications would become most promising in regard to an effective anticancer therapy, possibly with limited side-effects. However, most recent studies report on telomerase activity to be also expressed in normal, non-neoplastic tissues as well as in non-neoplastic hyperproliferative lesions. The questions whether telomerase activity is tumor-specific or associated with (physiologic or pathologic) hyperproliferation is intriguing and remains to be clarified.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1433-0563
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Die Aussicht, von einer malignen Tumorerkrankung geheilt zu werden, ist heute nur real, wenn die Erkrankung zum Zeitpunkt der Diagnose auf das Organ begrenzt ist. In Fällen eines organüberschreitenden Tumorwachstums oder nachgewiesener Metastasierung schließt sich nach der chirurgischen Sanierung je nach betroffenem Organ und Tumorstadium eine Strahlen- oder Chemotherapie an. Grundprinzip dieser Therapien ist es, die im Körper verbliebenen Tumorzellen wegen ihrer außer Kontrolle geratenen Proliferation auszuschalten. Unglücklicherweise haben diese Therapieansätze trotz vieler Modifikationen gezeigt, daß eben nicht nur der Metabolismus und die Replikationskaskade der Tumorzelle zerstört werden, sondern auch Zellen nicht neoplastischer Gewebe mit hoher physiologischer Zellteilungsrate, wie den Schleimhäuten des Darms, den Haarfollikeln und dem Knochenmark. Neben den zum Teil erheblichen Nebenwirkungen ist der erhoffte therapeutische Effekt, gemessen an den Remissionsraten und den Überlebensraten, zudem gering. Bei Neoplasien mit geringer Proliferation aber reduzierter Apoptosefähigkeit, eine Situation wie sie beispielsweise beim Prostatakarzinom besteht, ist diese Therapieform noch weniger erfolgversprechend. Hieraus ergibt sich die Forderung nach alternativen Tumortherapiekonzepten. Durch die breite Anwendung molekularbiologischer Techniken ist das Wissen über die molekularen Grundlagen vieler angeborener und erworbener Krankheiten stetig angewachsen. Während jedoch bei der Mucoviszidose und dem ADH-Mangel klar definierte, singuläre genetische Defekte Ansätze für gentherapeutische Maßnahmen bieten, sind die bisher bekannten Gendefekte in der Pathogenese maligner Tumoren um ein vielfaches komplexer. Nach tumorpathogenetischen Kriterien lassen sich den bereits bekannten morphologischen Phänomenen (a) der veränderten Proliferationsaktivität, (b) der Tumorblutversorgung, (c) der Tumorinvasion und (d) der Metastasierung zunehmend auch genetische Veränderungen auf molekularer Ebene zuordnen. Neben Mutationen in den bekannten Onkogenen und Tumorsuppressorgenen werden Veränderungen in zellzyklusregulierenden Genen sowie in Angioneogenese, Zelladhäsion oder die Immunreaktivität steuernden Genen für die Tumorpathogenese verantwortlich gemacht. Hieraus ergeben sich Ansätze für gentherapeutische Maßnahmen, mit dem Ziel, die Proliferation von Tumorzellen selektiv zu hemmen. Trotz der Komplexität der molekularen Pathogenese malignen Wachstums sind auch bei urologischen Neoplasien tumorspezifische genetische Veränderungen beschrieben, die Ansätze für eine Gentherapie bieten.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0942-0940
    Keywords: Pterional craniotomy ; orbitocygomatic resection ; orbital tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using standardized transcranial (pterional, subfrontal, frontoorbital) approaches, complete removal of tumours located in the latero-basal aspect of the orbit and the lateral orbital apex with or without extension to the temporal fossa is not possible or can only be achieved if excessive traction is applied to the contents of the orbit and the brain. In contrast, the combined pterional and orbitocygomatic approach provides unhindered access to the superior, lateral and latero-basal orbit, superior and inferior orbital fissure and, if required, to the temporal fossa including the foramina ovale and rotundum. Six patients with extensive orbital lesions underwent surgery using this technique with good operative results.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 136 (1995), S. 145-150 
    ISSN: 0942-0940
    Keywords: Lumbar microdiscectomy ; postoperative infection ; C-reactive protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The tendency for short hospitalization after lumbar microdiscectomy implies the need for early confirmation or disproval of serious postoperative infections such as spondylodiscitis or deep wound infections. The C-reactive protein (CRP) is a well-known screening parameter for monitoring postoperative infectious complications in other fields. Our objective was to establish the diagnostic significance of CRP-in comparison with ESR and WBC-for monitoring infectious complications after lumbar microdiscectomy. Over a 15 months period we studied prospectively a homogeneous group of N = 400 patients with lumbar disc herniations who were operated on a single level for the first time. CRP, ESR and WBC values were determined in all patients pre-operatively, and on postoperative days 1 and 5. Clinical and laboratory findings were correlated and the diagnostic significance of CRP, ESR and WBC calcualted. N = 385 (96%) patients had an uneventful postoperative course. N = 15 (4%) patients developed infectious complications, of which N = 6 (1.5%) were unrelated and N = 9 (2.5%) related to surgery. Evaluation of the laboratory values showed: The CRP baseline is a very individual value of no prognostic relevance. A high postaggression peak is typical and essential as a reference value for only the future time course will disclose any infection. We found 0% false negative and 4% false positive results on day 5. The sensitivity for serial CRP testing was calculated as 100% and specificity as 95.8%. ESR (sensitivity: 78.1%/specificity: 38.1%) and WBC (sensitivity: 21.4%/specificity: 76.8%) both failed to reach such distinct diagnostic significance on day 5. The C-reactive protein has thus proved to be a reliable, simple and economical screening test for infectious complications after lumbar microdiscectomy, superior to classical laboratory parameters.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0942-0940
    Keywords: SAH of unknown aetiology ; cerebral vasospasm ; transcranial Doppler sonography ; triple-H-therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sixteen patients (6 women, 10 men; mean age: 52.5 years) suffering from spontaneous subarachnoid haemorrhage (SAH) of unknown origin underwent a protocol of initial and then weekly computed tomography (CT), initial four-vessel digital subtraction angiography (DSA) and at least one control pancerebral DSA. Fourteen patients had magnetic resonance imaging before undergoing first control DSA. All patients had calcium-antagonists (Nimodipine) via a central venous catheter, were kept on the neurosurgical intensive care unit and followed daily with transcranial Doppler ultrasonography (TCD). One patient (6.3%) developed moderate and 5 (31.1%) developed severe cerebral vasospasm as documented with TCD and exhibited deterioration of their level of consciousness. These 6 patients were treated with induced hypertension, hypervolaemia and haemodilution. Their blood flow velocities were elevated for a mean of 8 (5–17) days with a peak after 12.5 (9–17) days following SAH. No complications due to treatment were noted. One patient of the non-vasospastic group died of pulmonary embolism, another patient had an ischaemic incident during angiography, which has led to permanent disability. On follow-up 2–24 months after SAH 14 patients had returned to their premorbid state. It is concluded that patients suffering from SAH of unknown origin should undergo repeated angiographic investigation and subsequent daily monitoring of their neurologic status including daily TCD recordings so that haemodynamic treatment can be established in the event of cerebral vasospasm, which may occur in up to one third of these patients.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0942-0940
    Keywords: Keywords: Cerebrospinal fluid; hydrocephalus; low ICP syndrome; pressure adjustable valve; slit ventricle syndrome; underdrainage.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Objective. Cerebrospinal fluid (CSF) over- and underdrainage symptoms are frequent sequelae of shunt placement in patients with hydrocephalus, sometimes requiring repeated operations. To achieve more adequate CSF drainage, the non-invasively programmable Hakim valve has been developed. Because the clinical experiences with this valve so far are confined to adults, we describe our experiences with the routine use of the programmable Hakim valve in childhood hydrocephalus.  Method. Sixty children (mean age of 3.4 years) with hydrocephalus of various aetiologies have been shunted with the programmable Hakim valve. In the majority of cases, initial opening pressures of between 100 and 120 mm H2O were selected. The mean follow-up period was 2.1 years.  Results. Thirty-three readjustment of the pressure setting of the valve were performed in 20 children because of CSF overdrainage (low intracranial pressure syndrome n=13, slit ventricle syndrome n=2, hygroma n=1), CSF underdrainage (n=3) and CSF leakage through the operation wound (n=1). The symptoms of inadequate CSF drainage were cured in 18 of the 20 children. The necessity for valve readjustments was independend of the aetiology of the hydrocephalus. Thirty-one complications requiring repeated operation occurred during the follow-up period, accounting for an annual complication rate of 24.6%. Three complications were valve-related.  Conclusion. In the majority of cases, the programmable Hakim valve allows the successful management of symptoms related to CSF over- and underdrainage by non-invasive change of the initial pressure setting of the valve. Therefore, the programmable Hakim valve should be considered as an alternative to non-programmable valves of advanced design.
    Type of Medium: Electronic Resource
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