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  • 1
    Electronic Resource
    Electronic Resource
    Bildgestützte Therapieplanung für die interventionelle stereotaktische Therapie von Hirntumoren (1996)
    Springer
    Der Radiologe 36 (1996), S. 737-743 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Therapieplanung ; Chemotherapie ; Finite-Elemente-Methode ; Key words Treatment planning ; Chemotherapy ; Finite elements method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A treatment planning system for stereotactical neurosurgery has been developed. A modular system has been designed which is readily extendable. Different modalities of tomography (CT, MRI) can be correlated and presented simultaneously in transverse, frontal and sagittal reconstructions. The volumes of interest are segmented with respect to the different modalities, and the positions of the catheters are defined. The calculation of dose must be adapted to the physical requirements of the therapy and is designed as an independent process. The calculated data are shown in various presentations. The treatment planning system is applied to intratumoral chemotherapy. The drug is encapsulated in small carriers for prolonged release and injected via catheters directly into the tumor interstitium, bypassing the blood-brain barrier. The dose is calculated using the time-dependent, three-dimensional finite elements method. To achieve homogeneous temporal and spatial drug distribution it is necessary to use a great number of catheters due to the limited diffusion of drug, which is not practical in neurosurgery. Therefore this therapy concept is useful for small volumes only. Interstitial hyperthermia and brachytherapy, in contrast to intratumoral chemotherapy, show successful clinical results.
    Notes: Zusammenfassung In dieser Arbeit wird ein Therapieplanungssystem für stereotaktische Anwendungen in der Neurochirurgie vorgestellt. Das Planungssystem ist als ein modulares, leicht erweiterbares Programmpaket realisiert, mit dem man Tomographieaufnahmen verschiedener Modalitäten (CT, MRT) korreliert und darstellt, Tumor und Risikoorgane segmentiert und Katheterpositionen definiert. Für unterschiedliche Therapieformen wie interstitielle Hyperthermie, intratumorale Chemotherapie oder Brachytherapie sind die Dosisberechnungen als ein eigenständiges Programm konzipiert worden. Die berechneten Ergebnisse werden in verschiedenen Darstellungen präsentiert. Eine Anwendung für das Therapieplanungssystem ist die intratumorale Chemotherapie. Bei dieser Therapie ist der Wirkstoff in Carrier verkapselt und wird über Katheter direkt in das Tumorgewebe appliziert. Die Dosisberechnung erfolgt mit der zeitabhängigen, dreidimensionalen Finite-Elemente-Methode. Die zeitliche und räumliche Darstellung der Wirkstoffverteilung zeigt, daß die intratumorale Chemotherapie aufgrund der großen Zahl an Kathetern nicht bei größeren Tumoren anwendbar ist. Im Gegensatz dazu zeigt die interstitielle Hyperthermie und die Brachytherapie auch bei größeren Tumoren gute klinische Ergebnisse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050136
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cytosolic free Ca2+ signals in single adherent human neutrophils: Generation and functional role (1993)
    Springer
    European journal of pediatrics 152 (1993), S. 26-32 
    Details
    ISSN: 1432-1076
    Keywords: Neutrophils ; Intracellular free calcium ; Fura-2 ; Integrins ; Phagocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To study the role of cytosolic free calcium, [Ca2+]i, in cell activation, in particular during adhesion and movement on a surface in response to chemotactic peptide stimulation and during phagocytosis, we monitored [Ca2+]i in single human neutrophils. The neutrophils were loaded with fura-2 and allowed to adhere to albumin-coated glass coverslips. [Ca2+]i was monitored with a dual excitation microfluorimeter. Half of the cells showed spontaneous [Ca2+]i transients that lasted up to 15 min with an amplitude averaging 77±10 nM above basal levels (mean basal value of 110±20 nM) and a mean duration of 28±5 s. These repetitive [Ca2+]i elevations depended on the continuous presence of extracellular Ca2+ and could be dissociated from those triggered by the chemotactic peptide N-formyl-methionyl-leucylphenylalanine (fMLP). Cell morphology was monitored in parallel by recording fluorescent images with a high sensitivity charge coupled device (CCD) camera. The majority of the cells studied showed visible changes in shape which started either before or at the same time as the onset of the [Ca2+]i transients. Removal of extracellular Ca2+ abolished [Ca2+]i transients without impairing cell movement and spreading. Blockade of adherence and cell movement with cytochalasin B markedly inhibited [Ca2+]i transients. Monoclonal antibodies directed against the leucocyte integrin CR3 (CD11b/CD18 αmβ2) blocked adherence, spreading and most of the [Ca2+]i activity. Total [Ca2+]i activity was assessed during phagocytosis of C3bi-opsonized yeast particles and correlated with fusion of secondary granules with the phagosomal membrane (P-L fusion). In Ca2+-containing medium, upon contact with a yeast particle, a rapid rise in [Ca2+]i was observed, followed by one or more Ca2+ peaks. P-L fusion was detected in 80% of the cells after 5–10 min. Increasing the cytosolic Ca2+ buffering capacity by loading the cells with MAPT/AM led to a dose-dependent inhibition both of [Ca2+]i elevations and P-L fusion. Under conditions where basal [Ca2+]i was reduced to 〈20 nM and intracellular Ca2+ stores were depleted, P-L fusion was drastically inhibited while the cells ingested yeast particles normally. Taken together these results indicate that: 1. The action of leucocyte integrins is necessary for the generation of the multiple [Ca2+]i transient observed in surface adherent human neutrophils. These [Ca2+]i transients do not preclude and can be dissociated from the response to fMLP and they prime the cell to subsequent stimulation. 2. Although the ingestion step of phagocytosis is a Ca2+-independent event, [Ca2+]i transients triggered upon contact with opsonized particles are necessary to control the subsequent fusion of granules with the phagosomal membrane. 3. Studies at a single cell level will be necessary to detect subtle deficiencies in intracellular mediators during human diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02072084
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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