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  • 1
    Electronic Resource
    Electronic Resource
    Steroids decrease uptake of carboplatin in rat gliomas – Uptake improved by intracarotid infusion of bradykinin analog, RMP-7 (1997)
    Springer
    Journal of neuro-oncology 34 (1997), S. 131-138 
    Details
    ISSN: 1573-7373
    Keywords: blood-brain barrier ; bradykinin ; brain tumor ; carboplatin ; glucocorticoid ; RG2 glioma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A blood-tumor barrier (BTB) limits delivery of antitumoragents to brain tumors. This study sought todetermine whether dexamethasone (DXN) treatment of rats withintracranial gliomas would 1) further impair delivery ofcarboplatin to brain tumors, and 2) whether intracarotidinfusion of the bradykinin analog, RMP-7, would improvedelivery during concurrent DXN treatment. Wistar rats withRG2 gliomas were utilized and a unidirectional transport,Ki, of radiolabeled [14C] carboplatin was determined usingquantitative autoradiography. In DXN pretreatment animals, 3 mg/kg/dayof DXN was administered intraperitoneally for 3 daysprior to Ki determinations. At 10 days aftertumor implantation, Ki of [14C] carboplatin into DXN-treatedtumors and brain surrounding tumor (BST) was significantlylower compared to non-DXN treated tumors and BST(3.30 ± 0.91 vs. 4.47 ± 1.80, p〈 0.05, and 0.94 ± 0.84 vs. 2.18± 0.79, p 〈 0.05, respectively). Intracarotid infusionof RMP-7 (0.1 mg/kg/min) significantly increased the Kifor carboplatin in DXN-treated tumors (6.35 ± 3.10vs. 3.30 ± 0.91, p 〈 0.01), however, RMP-7increased Ki to a greater extent in tumorsnot pretreated with DXN (12.07 ± 3.60 vs.4.47 ± 1.80, p 〈 0.0001). Our studiesshow that dexamethasone decreases transport of carboplatin intobrain tumors. Intracarotid infusion of RMP-7 selectively increasescarboplatin transport to tumors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005706329630
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  • 2
    Electronic Resource
    Electronic Resource
    Intravenous Infusion of RMP-7 Increases Ocular Uptake of Ganciclovir (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 80-85 
    Details
    ISSN: 1573-904X
    Keywords: blood-ocular barriers ; bradykinin ; drug delivery ; retina ; guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The ability of intravenous (i.v.) infusions of the bradykinin agonist, RMP-7, to permeabilize the blood-ocular barriers (BOB) to the antiviral agent ganciclovir was investigated in guinea-pigs. Methods. Different i.v. dosing regimens included pre-treatment with RMP-7 (0.2 μg/kg/min for 5 min) followed by either [3H]-ganciclovir (1 μCi/0.2 ml/min) alone, and/or co-infusion with RMP-7 and [3H]-ganciclovir. At specific times the animals were sacrificed, their eyes removed, and the retina and lens epithelium dissected and analyzed for the amount of radioactivity. Results. Using the ratio of tissue vs. integrated plasma radioactivity concentration, a two-fold increase in ganciclovir steady-state levels were observed in the retina as well as lens epithelium following RMP-7 pretreatment. Peak uptake effects were achieved with a 4.5 min ganciclovir infusion. Neither longer infusions of ganciclovir alone, nor co-infusions of RMP-7 and ganciclovir further enhanced the uptake effects. Kinetic analysis indicated that RMP-7 increased the rate of ganciclovir entry (K IN) in studied ocular tissues, while the efflux of drug (K OUT) was not affected by this treatment. Finally, ganciclovir retina:plasma ratios elevated by RMP-7 pre-treatment, remained higher than control ratios within 60 min following cessation of 4.5 min ganciclovir infusion. Conclusions. These data offer further evidence that BOB and in particular the blood-retinal barrier can be permeabilized via bradykinin receptor stimulation. As the i.v. infusions of RMP-7 enhanced the retinal uptake of ganciclovir, it is suggested that a combination of RMP-7 and ganciclovir may provide a novel approach for treating cytomegalo-virus retinis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012011618785
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  • 3
    Electronic Resource
    Electronic Resource
    Cereport™ (RMP-7) Increases the Permeability of Human Brain Microvascular Endothelial Cell Monolayers1 (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1360-1365 
    Details
    ISSN: 1573-904X
    Keywords: Cereport ; bradykinin B2 receptor ; human ; brain endothelium ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study Cereport (RMP-7, bradykinin B2 agonist) effects on human brain microvascular endothelial cell (HBMEC) monolayer permeability. Methods. HBMEC grown on transwell membranes were exposed to Cereport. The monolayer permeability was determined with [I4C]-inulin (MW. 5,200) and [3H]-dextran (MW. 70,000). Results. Cereport increased the HBMEC permeability to [l4C]-inulin, but not to [3H]-dextran. The effect was transient, maximal at 15 min (i.e., 79.3% increase), and polarized to the basolateral membrane. An inverted U, dose-response curve was observed with active concentrations of Cereport from 0.01 to 0.5 nmol/L, the plateau maximal effect between 0.5 and 10 nmol/L, and loss of activity at the highest concentration, i.e., 20 nmol/L. Cyclic AMP-specific phosphodiesterase 3 (PDE3) inhibitor rolipram (10 μmol/L) abolished Cereport effects, while cGMP-specific PDE5 inhibitor, zaniprast (50 μmol/L) enhanced by 31 % (p 〈 0.05) the effect of 0.1 nmol/L Cereport. Unlabeled Cereport displaced [12 5I]-bradykinin and/or [125I]-Cereport from the basolateral side. There was no specific Cereport binding to the apical side. Conclusions. Cereport exerts specific time, dose and size dependent actions on HMBEC monolayer that are restricted to the basolateral membrane. Its effects can be further modulated through changes in cAMP and cGMP second messenger systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018938722768
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  • 4
    Electronic Resource
    Electronic Resource
    Intravenous Cereport (RMP-7) Enhances Delivery of Hydrophilic Chemotherapeutics and Increases Survival in Rats with Metastatic Tumors in the Brain (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 1212-1219 
    Details
    ISSN: 1573-904X
    Keywords: blood-brain tumor barrier ; bradykinin ; brain metastases ; carboplatin ; carmustine ; paclitaxel ; vinorelbine ; gemcitabine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The following experiments determined whether intravenous infusions of Cereport enhance delivery of chemotherapeutics and prolong survival in rats with metastatic tumors in the brain. Methods. Autoradiography and scintillation were used to examine uptake of the lipophilic (paclitaxel and carmustine) and the hydrophilic (carboplatin) chemotherapeutic agents, as well as the large hydrophilic marker, 70 kDa dextran. Cereport was also tested in combination with the chemotherapeutic drugs carboplatin, vinorelbine, gemcitabine and carmustine to determine if Cereport could enhance the survival benefit beyond that provided by chemotherapy alone. Results. Cereport enhanced the uptake of carboplatin and dextran, but not paclitaxel or carmustine. The pattern of Cereport's uptake effect with carboplatin revealed that Cereport selectively increased the proportion of highly permeable regions. Survival was significantly enhanced when Cereport was combined with either carboplatin, vinorelbine, or gemcitabine, but not carmustine, compared to each chemotherapeutic agent alone. Conclusions. These data provide the first evidence that Cereport, or any receptor-mediated approach intended to enhance the permeability of the blood-brain tumor barrier, can increase the delivery hydrophilic drugs to metastatic tumors in the brain, increasing survival in tumor-bearing rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026462629438
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