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  • 1
    Electronic Resource
    Electronic Resource
    Efflux of a suppressive neurotransmitter, GABA, across the blood–brain barrier (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 79 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this study, GABA efflux transport from brain to blood was estimated by using the brain efflux index (BEI) method. [3H]GABA microinjected into partietal cortex area 2 (Par2) of the rat brain was eliminated from the brain with an apparent elimination half-life of 16.9 min. The blood–brain barrier (BBB) efflux clearance of [3H]GABA was at least 0.153 mL/min/g brain, which was calculated from the elimination rate constant (7.14 × 10−2 min−1) and the distribution volume in the brain (2.14 mL/g brain). Direct comparison of the apparent BBB influx clearance [3H]GABA (9.29 µL/min/g brain) and the apparent efflux clearance (153 µL/min/g brain) indicated that the efflux clearance was at least 16-fold greater than the influx clearance. In order to reduce the effect of metabolism in the neuronal cells following intracerebral microinjection, we determined the apparent efflux of [3H]GABA in the presence of nipecotic acid, a GABA transport inhibitor in parenchymal cells, using the BEI method. Under such conditions, the elimination of [3H]GABA across the BBB showed saturation and inhibition by probenecid in the presence of nipecotic acid. Furthermore, the uptake of [3H]GABA by MBEC4 cells was inhibited by GABA, taurine, β-alanine and nipecotic acid in a concentration-dependent manner. It is likely that GABA inhibits the first step in the abluminal membrane uptake by brain endothelial cells, and that probenecid selectively inhibits the luminal membrane efflux transport process from the brain capillary endothelial cells based on the in vivo and in vitro evidence. The BBB acts as the efflux pump for GABA to reduce the brain interstitial fluid concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00540.x
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  • 2
    Electronic Resource
    Electronic Resource
    Reversal of multidrug resistance by a novel quinoline derivative, MS-209 (1995)
    Springer
    Cancer chemotherapy and pharmacology 35 (1995), S. 271-277 
    Details
    ISSN: 1432-0843
    Keywords: MS-209 ; Quinoline ; Multidrug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MS-209, a novel quinoline derivative, was examined for its reversing effect on multidrug-resistant tumor cells. MS-209 at 1–10 μM completely reversed resistance against vincristine (VCR) in vitro in multidrug-resistant variants of mouse leukemia P388 cells (VCR-resistant P388/VCR and Adriamycin (ADM)-resistant P388/ADM) and human leukemia K562 cells (VCR-resistant K562/VCR and ADM-resistant K562/ADM). MS-209 at 1–10 μM also completely reversed resistance against ADM in vitro in P388/VCR cells, K562/VCR cells, and K562/ADM cells. In ADM-resistant P388 (P388/ADM) cells, however, ADM resistance was only partially reversed at the MS-209 concentrations tested. MS-209 enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When MS-209 was given p.o. at 80 mg/kg twice a day (total dose, 160 mg/kg per day) with 100 μg/kg VCR, a treated/control (T/C) value of 155% was obtained. MS-209 also enhanced the chemotherapeutic effect of ADM in P388/ADM-bearing mice. The most prominent effects were obtained when MS-209 was given with 2 mg/kg ADM, yielding T/C values of 150%–194% for the combined treatment at an MS-209 dose of 200–450 mg/kg. MS-209 inhibited [3H]-azidopine photolabeling of P-glycoprotein efficiently. Furthermore, the accumulation of ADM in K562/ADM cells was increased more eficiently by MS-209 than by verapamil. These results indicate that MS-209, like verapamil, directly interacts with P-glycoprotein and inhibits the active efflux of antitumor agents, thus overcoming multidrug resistance in vitro and in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689444
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  • 3
    Electronic Resource
    Electronic Resource
    Relationship between multidrug resistant gene expression and multidrug resistant-reversing effect of MS-209 in various tumor cells (1995)
    Springer
    Cancer chemotherapy and pharmacology 36 (1995), S. 361-367 
    Details
    ISSN: 1432-0843
    Keywords: MS-209 ; MDR ; RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MS-209 is a novel quinoline compound which can overcome multidrug resistance (MDR) both in vitro and in vivo, while having a low level of side effects, and is now being evaluated in a clinical phase II study. Reverse transcription-polymerase chain reaction (RT-PCR) was used to quantitative the expression levels ofMDR genes in various mouse and human tumor cell lines. TheMDR gene and the βactin gene, as the internal reference standard, were coamplified separately, and the relative expression of theMDR gene was represented by the MDR/β actin ratio. The in vitro MDR-reversing effect of MS-209 was then compared with theMDR gene expression (MDR/β actin ratio). We found a significant correlation between these two parameters. Moreover, a significant correlation was also observed between the level of expression of theMDR1 gene and that of P-glycoprotein in human cell lines. Therefore, the efficacy of MS-209 seems to specifically depend on the level ofMDR gene expression (P-glycoprotein). From these observations, it is suggested that RT-PCR assays ofMDR1 gene in tumor biopsy specimens might be an effective means to predict the response of tumor cells to combination therapy with MS-209.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686183
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  • 4
    Electronic Resource
    Electronic Resource
    Relationship between multidrug resistant gene expression and multidrug resistant-reversing ef fect of MS-209 in various tumor cells (1995)
    Springer
    Cancer chemotherapy and pharmacology 36 (1995), S. 361-367 
    Details
    ISSN: 1432-0843
    Keywords: Key words MS-209 ; MDR ; RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  MS-209 is a novel quinoline compound which can overcome multidrug resistance (MDR) both in vitro and in vivo, while having a low level of side effects, and is now being evaluated in a clinical phase II study. Reverse transcription–polymerase chain reaction (RT-PCR) was used to quantitate the expression levels of MDR genes in various mouse and human tumor cell lines. The MDR gene and the ß actin gene, as the internal reference standard, were coamplified separately, and the relative expression of the MDR gene was represented by the MDR/ß actin ratio. The in vitro MDR-reversing effect of MS-209 was then compared with the MDR gene expression (MDR/ß actin ratio). We found a significant correlation between these two parameters. Moreover, a significant correlation was also observed between the level of expression of the MDR1 gene and that of P-glycoprotein in human cell lines. Therefore, the efficacy of MS-209 seems to specifically depend on the level of MDR gene expression (P-glycoprotein). From these observations, it is suggested that RT-PCR assays of MDR1 gene in tumor biopsy specimens might be an effective means to predict the response of tumor cells to combination therapy with MS-209.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686183
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  • 5
    Electronic Resource
    Electronic Resource
    Activation of mouse peritoneal macrophages by synthetic glyceroglycolipid liposomes (1987)
    Springer
    Cancer immunology immunotherapy 24 (1987), S. 158-164 
    Details
    ISSN: 1432-0851
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Liposomes composed of chemically synthesized glyceroglycolipids, such as 1,2-dipalmityl-[β-cellobiosyl-(1′ → 3)]-glycerol (Cel-DAG), 1,2-dipalmityl-[β-lactosyl-(1′ → 3)]-glycerol, or 1,2-dipalmityl-[β-maltosyl-(1′ → 3)]-glycerol, were found to enhance protective immunity against transplantable tumor cells (sarcoma 180) in ICR mice. Peritoneal exudate cells prepared from mice treated in vivo with Cel-DAG showed cytostatic activity in vitro against the mouse leukemia cell line, EL-4. Adherent cells separated from this preparation showed similar activity. Peritoneal cells from polypeptone-injected mice acquired appreciable cytostatic activity when incubated in vitro in the presence of glyceroglycolipid liposomes. The adherent cell fraction alone showed rather weak cytostatic activity when pretreated with the glyceroglycolipids, and full activity was restored by supplementing with the nonadherent cell fraction. The ability of glycolipids to induce tumoricidal effects was affected by cholesterol content: with increasing cholesterol content, the activities decreased. Cholesterol-free glycolipid liposomes were taken more efficiently by macrophages than cholesterol-containing liposomes. Cholersterol modifies the surface property of glyceroglycolipid liposomes. Activation of macrophages is responsible for enhancement of protective immunity against tumor cells by injection of these glycolipids in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205594
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  • 6
    Electronic Resource
    Electronic Resource
    Reversal of multidrug resistance by an immunosuppressive agent FK-506 (1992)
    Springer
    Cancer chemotherapy and pharmacology 29 (1992), S. 195-200 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary FK-506, a novel immunosuppressive agent, was examined for its reversing effect on multidrug-resistant tumor cells. FK-506 at 3 μM completely reversed the resistance against vincristine (VCR) in vitro in VCR-resistant mouse leukemia P388 cells (P388/VCR). FK-506 also enhanced the cytotoxicity of VCR in Adriamycin(ADM)-resistant human ovarian cancer A2780 cells (AD10) and ADM-resistant human myelogenous leukemia K562 cells (K562/ADM) in vitro. FK-506 was also effective in modulating sensitivity to ADM in AD10 cells in vitro. FK-506 enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When 20 mg/kg FK-506 was combined with 200 μg/kg VCR, a T/C value of 151% was obtained. Under the protocol used in this study, FK-506 was more potent than cyclosporin A (CsA) and verapamil. FK-506 inhibited [3H]azidopine binding to P-glycoprotein efficiently. The binding of VCR to K562/ADM plasma membrane was inhibited by FK-506 as effectively as by CsA. Moreover, the accumulation of VCR in AD10 cells was increased by FK-506 as efficiently as that of CsA and verapamil. These results indicate that FK-506 directly interacts with P-glycoprotein like CsA and verapamil, inhibits the active efflux of vincristine from resistant cells, increases the vincristine accumulation in resistant cells, and thus overcomes multidrug resistance in vitro and in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686252
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  • 7
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a mitomycin C-resistant variant of human colon carcinoma HT-29 cells (1993)
    Springer
    Cancer chemotherapy and pharmacology 33 (1993), S. 215-220 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate the resistant mechanisms against MMC in human tumor cells, we isolated an MMC-resistant variant (HT-29/MMC) of HT-29 human colon carcinoma cells. HT-29/MMC cells showed 5-fold resistance to MMC as compared with the parental cell line but did not show cross-resistance to Adriamycin, vincristine, ACNU, bleomycin, or cisplatin. Treatment of the cells with dicoumarol, an inhibitor of DT-diaphorase, reduced the cytotoxicity of MMC in DT-diaphorase proficient HT-29 cells but not in HT-29/MMC cells. HT-29/MMC cells were 5 times more sensitive than HT-29 cells to menadione, which is detoxified by DT-diaphorase. DT-diaphorase was deficient in HT-29/MMC cells as determined by the enzyme activity and immunoblot analysis of the cytoplasmic proteins. Levels of cytochrome P-450 reductase and glutathione S-transferase, however, were comparable in both cell lines. The amount of [3H]-MMC found covalently bound to chromosomal DNA in HT-29/MMC cells was one-fourth that detected in HT-29 cells. Treatment with dicoumarol reduced the DNA-bound MMC in HT-29 cells but not in HT-29/MMC cells. These results indicate that the deficiency in DT-diaphorase, an activating enzyme of MMC, is one of the mechanisms of resistance in HT-29/MMC cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686219
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  • 8
    Electronic Resource
    Electronic Resource
    Reversal of multidrug resistance by a novel quinoline derivative, MS-209 (1995)
    Springer
    Cancer chemotherapy and pharmacology 35 (1995), S. 271-277 
    Details
    ISSN: 1432-0843
    Keywords: Key words MS-209 ; Quinoline ; Multidrug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  MS-209, a novel quinoline derivative, was examined for its reversing effect on multidrug-resistant tumor cells. MS-209 at 1–10 μM completely reversed resistance against vincristine (VCR) in vitro in multidrug-resistant variants of mouse leukemia P388 cells (VCR-resistant P388/VCR and Adriamycin (ADM)-resistant P388/ADM) and human leukemia K562 cells (VCR-resistant K562/VCR and ADM-resistant K562/ ADM). MS-209 at 1–10 μM also completely reversed resistance against ADM in vitro in P388/VCR cells, K562/VCR cells, and K562/ADM cells. In ADM-resistant P388 (P388/ADM) cells, however, ADM resistance was only partially reversed at the MS-209 concentrations tested. MS-209 enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When MS-209 was given p.o. at 80 mg/kg twice a day (total dose, 160 mg/kg per day) with 100 μg/kg VCR, a treated/control (T/C) value of 155% was obtained. MS-209 also enhanced the chemotherapeutic effect of ADM in P388/ADM-bearing mice. The most prominent effects were obtained when MS-209 was given with 2 mg/kg ADM, yielding T/C values of 150%–194% for the combined treatment at an MS-209 dose of 200–450 mg/kg. MS-209 inhibited [3H]-azidopine photolabeling of P-glycoprotein efficiently. Furthermore, the accumulation of ADM in K562/ADM cells was increased more efficiently by MS-209 than by verapamil. These results indicate that MS-209, like verapamil, directly interacts with P-glycoprotein and inhibits the active efflux of antitumor agents, thus overcoming multidrug resistance in vitro and in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689444
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  • 9
    Electronic Resource
    Electronic Resource
    Reconstitution of purified P-glycoprotein into liposomes (1995)
    Springer
    Journal of cancer research and clinical oncology 121 (1995), S. 582-586 
    Details
    ISSN: 1432-1335
    Keywords: P-glycoprotein ; Reconstitution ; Liposome ; Transport ; Vincristine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To study the molecular function of the multidrug-resistance gene product P-glycoprotein, we purified and reconstituted it into liposomes. Twelve detergents were examined in an attempt to solubilize and reconstitute the transport activity of K562/ADM membrane proteins containing P-glycoprotein. We found that transport activity was effectively reconstituted after solubilization with cholate, glycocholate and taurocholate. Other detergents, such as CHAPS, Triton X-100 and deoxycholate, diminished the transport activity. The K562/ADM membrane was solubilized by 1% glycocholate, and P-glycoprotein was purified by MRK-16 immunoaffinity column chromatography to a homogeneous single band on sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The purified P-glycoprotein was reconstituted by detergent dialysis into liposomes composed of phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine. The reconstituted P-glycoprotein specifically bound [3H]azidopine and had an ATPase activity that was slightlystimulated when vincristine was added. Furthermore, though its activity was reduced, the reconstituted P-glycoprotein was shown to be an ATP-dependent transporter of vincristine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197774
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  • 10
    Electronic Resource
    Electronic Resource
    Enhanced metastasis of B16 melanoma cells by unexpected elevated expression of the metastasis-associatedTI-241 (LRF-1-, Jun-Fos-related) gene treated with antisense oligonucleotide (1998)
    Springer
    Clinical & experimental metastasis 16 (1998), S. 179-183 
    Details
    ISSN: 1573-7276
    Keywords: antisense oligonucleotide ; B16 melanoma ; metastasis ; TI-241
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract B16-F10 is a B16 mouse melanoma subline that preferentially metastasizes to the lung following intravenous injection. Previously we isolated TI-241 (LRF-1 homologue related to Jun-Fos) gene that was expressed higher in the high metastatic clone B16-F10 than the low metastatic clone F1. Transfection of TI-241 into F1 converted it into a high-metastatic cell. We studied the effect of antisense oligonucleotide designed to reduce the expression of TI-241 in B16-F10 cells, and observed an unexpected increase in the TI-241 level. The increase in the expression was maximal at 30 h, then it decreased during further culture with or without TI-241 antisense oligonucleotide. This increased TI-241 expression by antisense oligonucleotide was also observed in B16-F1cells whereas sense oligonucleotide did not affect the expression. B16-F10 cells cultured with TI-241 antisense oligonucleotide showed enhanced experimental metastatic potential to the mouse lungs compared with untreated B16-F10 and B16-F10 cultured with TI-241 sense oligonucleotide. © Rapid Science 1998
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006528422244
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