Lancet, 2000 Sep 23, 356(9235), 1066 - 71 Tuberculosis control and molecular epidemiology in a South African gold-mining community; Godfrey-Faussett P et al.; BACKGROUND: Gold miners have very high rates of tuberculosis . The contribution of infections imported into mining communities versus transmission within them is not known and has implications for control strategies . METHODS: We did a prospective, population-based molecular and conventional epidemiological study of pulmonary tuberculosis in a group of goldminers . Clusters were defined as groups of patients with Mycobacterium tuberculosis isolates with identical IS6110 DNA fingerprints . We compared the frequency of possible risk factors in the clustered and non-clustered patients whose isolates had fingerprints with more than four bands, and re-interviewed members of 45 clusters . FINDINGS: Of 448 patients, ten were excluded because they had false-positive cultures . Fingerprints were made in 419 of 438, of which 371 had more than four bands . 248 of 371 were categorised into 62 clusters . At least 50% of tuberculosis cases were due to transmission within the community . Patients who had failed treatment at entry to the study were more likely to be in clusters (adjusted odds ratio 3.41 {95% CI 1.25-9.27}) . Patients with multidrug-resistant isolates were more likely to have failed treatment but were less likely to be clustered than those with a sensitive strain (0.27 {0.09-0.83}) . HIV infection was common (177 of 370 tested) but not associated with clustering . INTERPRETATION: Despite a control programme that cures 86% of new cases, most tuberculosis in this mining community is due to ongoing transmission . Persistently infectious individuals who have previously failed treatment may be responsible for one third of tuberculosis cases . WHO targets for cure rates are not sufficient to interrupt transmission of tuberculosis in this setting . Indicators that are more closely linked to the rate of ongoing transmission are needed. Biochem Pharmacol, 2000 Nov 1, 60(9), 1381 - 90 Phospholipids as multidrug resistance modulators of the transport of epirubicin in human intestinal epithelial Caco-2 cell layers and everted gut sacs of rats; Lo YL; Phospholipids have been increasingly used as carriers for the delivery of a variety of drugs . Studies using cancer chemotherapeutic agents such as epirubicin encapsulated in liposomes, which are made of phospholipids and other ingredients, have generally shown reduced toxicity and enhanced therapeutic efficacy . The recent investigation of the role of P-glycoprotein (P-gp) in phospholipid translocation has opened a new area of research on the possible use of phospholipids as multidrug resistance (MDR) modulators . This study investigated the effects of liposomal encapsulation, empty liposome pretreatment, or free lipid pretreatment on the uptake and transport of epirubicin in the human colon adenocarcinoma cell line Caco-2 and in everted gut sacs of rat jejunum and ileum . Epirubicin uptake experiments, using a flow cytometer, showed that both liposomal encapsulation and empty liposome pretreatment increased the intracellular accumulation of epirubicin in Caco-2 cells significantly . These two treatments substantially increased apical-to-basolateral absorption of epirubicin across Caco-2 monolayers and markedly improved mucosal-to-serosal absorption of epirubicin in rat jejunum and ileum . Enhancement also was observed with both liposome encapsulation and empty liposome pretreatment in the reduction of basolateral-to-apical efflux of epirubicin across Caco-2 monolayers . However, because diffusion of free dipalmitoyl phosphatidylcholine (DPPC) or dipalmitoyl phosphatidylethanolamine (DPPE) lipids across the cell membrane is very slow, these free lipids showed marginal effects on absorption and/or secretion of epirubicin in both Caco-2 cells and rat gut sacs . The study suggests that inhibition of P-gp or other transporter proteins located in the intestines may be partially involved in the reduction of epirubicin efflux . In conclusion, the therapeutic efficacy of epirubicin may be improved by using phospholipids as excipients and MDR modulators in the formulations . Liposomal formulations may have important applications to circumvent drug resistance in cancer chemotherapy. Biochem Biophys Res Commun, 2000 Sep 16, 276(1), 231 - 7 Equivalent death of P-glycoprotein expressing and nonexpressing cells induced by the protein kinase C inhibitor staurosporine; Tainton KM et al.; P-glycoprotein (P-gp) is an ATP-dependent drug pump that confers multidrug resistance . In addition to its ability to efflux toxins P-gp can also inhibit apoptosis induced by a wide array of cell death stimuli that rely on activation of intracellular caspases for full function . We have previously demonstrated that stimuli including drugs such as hexamethylene bisacetamide (HMBA), the cytotoxic lymphocyte granule protein granzyme B, and pore-forming proteins such as perforin, kill P-gp positive cells in a caspase-independent manner . We therefore hypothesised that drugs that are not effluxed by P-gp and which induce cell death in the absence of caspase activation could induce death of P-gp expressing cells . Staurosporine has been previously shown to kill cells in the absence of caspase activation . Consistent with our hypothesis, we demonstrate here that staurosporine can equivalently kill P-gp(+ve) and P-gp(-ve) tumor cell lines in a caspase-independent manner . Int J Cancer, 2000 Oct 15, 88(2), 260 - 6 New highly lipophilic camptothecin BNP1350 is an effective drug in experimental human cancer; Van Hattum AH et al.; BNP1350, 7-{(2-trimethylsilyl)ethyl}-20(S)-camptothecin, is a novel semi-synthetic, highly lipophilic, silicon-containing camptothecin and an inhibitor of topoisomerase I . It has been supercomputer engineered for superior oral bioavailability, superior lactone stability, broad anti-tumor activity, increased potency and insensitivity to Pgp/MRP/LRP drug resistance . We determined the efficacy of BNP1350 in experimental human colon cancer and compared its anti-tumor effects with those of CPT-11/SN-38 . We also determined a possible influence of Pgp, MRP and LRP on the efficacy of BNP1350 . The in vitro anti-proliferative capacity of the compounds using various exposure times was assessed in five colon cancer cell lines and indicated that BNP1350 was similarly effective or slightly more potent than SN-38 . Four cell lines of other origin with sublines expressing Pgp, MRP and/or LRP showed that BNP1350 was significantly more effective than SN-38 (p < 0.05) and that the activity of BNP1350 was not reduced in multidrug-resistant cells . For in vivo experiments, BNP1350 was given 1.0 mg/kg i.p . or 1.5 mg/kg p.o . daily x 5 and CPT-11 20 mg/kg i.p . daily x 5 being equitoxic schedules in nude mice bearing s.c . human tumor xenografts . The schedules were studied in colon cancer xenografts COLO320, COLO205 or WiDr as well as in two Pgp-positive xenografts 2780AD and BRO/mdr1.1 and the parental Pgp-negative A2780 ovarian cancer xenografts and BRO melanoma xenografts . Growth inhibition of >50% was obtained for BNP1350 given i.p . in six out of the seven xenografts studied . BNP1350 was similarly effective when given i.p . or p.o . CPT-11 was as effective as BNP1350, except in BRO and BRO/mdr1.1 xenografts . Pgp expression in xenografts in vivo confirmed that there was no negative influence on the efficacy of BNP1350 . In conclusion, BNP1350 shows a broad spectrum of activity in experimental human tumors and is a suitable candidate for oral treatment of cancer . Am J Physiol Regul Integr Comp Physiol, 2000 Oct, 279(4), R1495 - 503 Expression of members of the multidrug resistance protein family in human term placenta; St-Pierre MV et al.; The placenta serves, in part, as a barrier to exclude noxious substances from the fetus . In humans, a single-layered syncytium of polarized trophoblast cells and the fetal capillary endothelium separate the maternal and fetal circulations . P-glycoprotein is present in the syncytiotrophoblast throughout gestation, consistent with a protective role that limits exposure of the fetus to hydrophobic and cationic xenobiotics . We have examined whether members of the multidrug resistance protein (MRP) family are expressed in term placenta . After screening a placenta cDNA library, partial clones of MRP1, MRP2, and MRP3 were identified . Immunofluorescence and immunoblotting studies demonstrated that MRP2 was localized to the apical syncytiotrophoblast membrane . MRP1 and MRP3 were predominantly expressed in blood vessel endothelia with some evidence for expression in the apical syncytiotrophoblast . ATP-dependent transport of the anionic substrates dinitrophenyl-glutathione and estradiol-17-beta-glucuronide was also demonstrated in apical syncytiotrophoblast membranes . Given the cellular distribution of these transporters, we hypothesize that MRP isoforms serve to protect fetal blood from entry of organic anions and to promote the excretion of glutathione/glucuronide metabolites in the maternal circulation. Eur J Cancer, 2000 Oct, 36(15), 1974 - 83 Cross-resistance in the 2',2'-difluorodeoxycytidine (gemcitabine)-resistant human ovarian cancer cell line AG6000 to standard and investigational drugs; Bergman AM et al.; Gemcitabine (2'-2'-difluorodeoxycytidine; dFdC) is a deoxycytidine analogue which is effective against solid tumours, including lung cancer and ovarian cancer . dFdC requires phosphorylation by deoxycytidine kinase (dCK) for activation . In the human ovarian cancer cell line A2780 and its 30,000-fold dFdC-resistant variant AG6000 (P<0.001), we investigated the cross-resistance profile to several drugs . AG6000, which has a complete dCK deficiency, was approximately 1000-10,000-fold resistant to other deoxynucleoside analogues such as 1-beta-D-arabinofuranosyl cytosine, 2-chloro-deoxyadenosine, aza-deoxycytidine and 2', 2'-difluorodeoxyguanosine (dFdG) (P<0.001) . dFdG can be activated by dCK and deoxyguanosine kinase (dGK), but the latter enzyme was not altered in AG6000 cells . Thus dFdG resistance was only due to dCK deficiency . AG6000 was 1.6- and 46.7-fold resistant to 5-fluorouracil (5-FU) and ZD1694, respectively (the latter was significant; P<0.01), which may be due to the 1.7-fold higher thymidylate synthase (TS) activity, but AG6000 cells were also 2 . 7-fold resistant to the lipophilic TS inhibitor AG337 (P<0.05) . Remarkably, AG6000 cells were 2.5-fold more sensitive to methotrexate (MTX) (P<0.01) than A2780 cells, but 1.6-fold more resistant to trimetrexate (TMQ) (P<0.10) . However, no differences in reduced folate carrier activity, folylpolyglutamate synthetase (FPGS) activity and polyglutamation of MTX were found between the cell lines . AG6000 cells were approximately 2 to 7.5-fold more resistant to doxorubicin (DOX), daunorubicin (DAU), epirubicin and vincristine (VCR) (the latter was significant; P<0.02) and approximately 4-fold more resistant to the microtubule inhibitors paclitaxel and docetaxel (P<0.001) . Fluorescent activated cell sorter (FACS) analysis revealed no P-glycoprotein (Pgp) or multidrug resistance-associated protein (MRP) expression, but less fluorescence of intercalated DAU in AG6000 cells . An approximately 2-fold resistance to the topoisomerase I and II inhibitors etoposide, CPT-11 and SN38 was found in AG6000 cells . Topoisomerase I and IIalpha RNA expression was decreased in AG6000 cells . AG6000 was 2.4, 2.4, 2.3 and 3.7-fold more resistant to EO9 (P<0.02), mitomycin-C (MMC) (P<0.05), cisplatin (CDDP) (P<0.10) and maphosphamide (MAPH), respectively . DT-diaphorase (DTD), which activates EO9, was 2.2-fold lower in AG6000 cells . CDDP resistance might be related to a reduced retention of DNA adducts in AG6000 . However, glutathione levels were equal in A2780 and AG6000 cells . A 24 h exposure to DOX, VCR and paclitaxel at equimolar and equitoxic concentrations, resulted in more double-strand breaks (1.5- to 2-fold) in A2780 than in AG6000 cells . MAPH at 1120 nM and 17 nM of EO9 did not cause DNA damage in either cell line . In conclusion, AG6000 is a cell line highly cross-resistant to a wide variety of drugs . This cross-resistance might be related to altered enzyme activities and/or increased DNA repair. Clin Cancer Res, 2000 Sep, 6(9), 3417 - 23 Clinical relevance of the lung resistance protein in diffuse large B-cell lymphomas; Filipits M et al.; Drug resistance of non-Hodgkin's lymphomas may involve mechanisms of the multidrug resistance phenotype including the lung resistance protein (LRP) and the multidrug resistance protein (MRP1) . To determine the clinical relevance of these multidrug resistance factors in previously untreated diffuse large B-cell lymphomas (n = 48), we studied LRP and MRP1 expression in lymphoma cells and their impact on clinical outcome . LRP and MRP1 expression were immunohistochemically assessed by means of the monoclonal antibodies LRP-56 and MRPr1, respectively . LRP was positive in 23% and MRP1 in 44% of the samples . LRP expression was associated with higher tumor stage (P = 0.03), elevated serum lactate dehydrogenase levels (P = 0.01), and the International Prognostic Index (P = 0.0001) . LRP-positive patients had a lower complete response rate to polychemotherapy than LRP-negative patients (18 versus 65%; P = 0.006) . Patients with LRP expression had a shorter overall survival than those without LRP expression (median of 0.9 years versus median not reached; P = 0.001) . MRP1 expression was independent of clinical and laboratory parameters and had no impact on the outcome of chemotherapy or survival of the patients . These data suggest that LRP expression but not MRP1 expression is an important mechanism of drug resistance associated with worse clinical outcome in previously untreated diffuse large B-cell lymphomas . Thus, the reversal of LRP-mediated drug resistance may improve clinical outcome in diffuse large B-cell lymphoma in the future. Emerg Infect Dis, 2000 Sep-Oct, 6(5), 548 - 51 Double infection with a resistant and a multidrug-resistant strain of Mycobacterium tuberculosis; Niemann S et al.; An immunocompetent patient was dually infected with a resistant and a multidrug-resistant strain of Mycobacterium tuberculosis (TB) . The multidrug-resistant strain, which belongs to the W- strain/Beijing family, was first isolated after 3 months of therapy . Inappropriate treatment led to further drug resistance and unsuccessful therapy . Thus, additional infections with resistant M . tuberculosis strains should be considered when tuberculosis therapy fails. Br J Haematol, 2000 Sep, 110(3), 591 - 8 Expression of the multidrug resistance-associated protein in myelodysplastic syndromes; Poulain S et al.; In the myelodysplastic syndromes (MDS), P-glycoprotein (P-gp) expression is clinically associated with drug resistance, whereas the clinical significance of multidrug resistance-associated protein (MRP1) is uncertain . Bone marrow from 56 patients with MDS, including six with refractory anaemia (RA)/RA with ringed sideroblasts (RARS), 23 cases of RA with excess blasts/in transformation (RAEB/T), four patients with chronic myelomonocytic leukaemia (CMML) and 23 cases of MDS having progressed to acute myeloid leukaemia (MDS-AML), were studied . MRP1 expression was investigated by immunocytochemistry (ICC) and by flow cytometry using MRPm6 monoclonal antibody . The efflux test using calcein-AM (CAM) +/- probenecid to evaluate MRP1 activity was performed in ten of the 56 patients . Twenty-eight of the 56 cases (50%) expressed MRP1 . MRP1 expression was more frequent in MDS-AML than in MDS (70% vs . 36%) . The efflux test using CAM was positive in three out of the ten patients tested . The results were in agreement with expression of MRP1 in six cases, and were discordant in four cases (1 MRP-/CAM+, 3 MRP+/CAM-) . No correlation was observed between MRP1 expression and P-gp, lung resistance-associated protein (LRP) or CD34 expression, although there was a trend for more frequent MRP1 expression in P-gp-positive cases in MDS-AML (P = 0.08) . Ten of the 26 patients treated with intensive chemotherapy achieved complete remission including six out of 16 MRP1+ and four out of ten MRP1- cases (P = NS) . In conclusion, MRP1 expression was correlated with disease stage in MDS in our study . As for P-gp, discordant expression/function of MRP1 could be found in some cases, suggesting the existence of non-functional transport proteins in MDS . MRP1 expression did not seem to be a prognostic factor in MDS in our experience. J Pharm Pharm Sci, 2000 May-Aug, 3(2), 268 - 80 Regulation of the multidrug resistance genes by stress signals; Sukhai M et al.; Transporters in the body play a large role in the distribution and elimination of many clinically important therapeutic substances . Of these, perhaps the one that has been best studied is P-Glycoprotein (PGP), a 170 kDa membrane-bound protein which has been implicated as a primary cause of multidrug-resistance in tumors . An understanding of the physiological regulation of these transporters is key to designing strategies for the improvement of therapeutic efficacy of drugs which are their substrates . To that end, we examine herein the current state of understanding of the molecular regulation of PGP by a variety of endogenous and environmental stimuli which evoke stress responses including cytotoxic agents, heat shock, irradiation, genotoxic stress, inflammation, inflammatory mediators, cytokines and growth factors. J Pharmacol Exp Ther, 2000 Oct, 295(1), 360 - 6 Secretory mechanisms of grepafloxacin and levofloxacin in the human intestinal cell line caco-2; Yamaguchi H et al.; Grepafloxacin and levofloxacin transport by Caco-2 cell monolayers was examined to characterize the intestinal behavior of these quinolones . The levels of transcellular transport of {(14)C}grepafloxacin and {(14)C}levofloxacin from the basolateral to the apical side were greater than those in the opposite direction . The unidirectional transport was inhibited by the presence of excess unlabeled quinolones, accompanied by increased accumulation . The inhibitory effects of cyclosporin A plus grepafloxacin on basolateral-to-apical transcellular transport and cellular accumulation of {(14)C}grepafloxacin were comparable to those of cyclosporin A alone, indicating that the transport of grepafloxacin across the apical membrane was mainly mediated by P-glycoprotein . On the other hand, basolateral-to-apical transcellular transport of {(14)C}levofloxacin in the presence of cyclosporin A was decreased by unlabeled levofloxacin, grepafloxacin, and enoxacin, accompanied by significantly increased cellular accumulation . The organic cation cimetidine, organic anion p-aminohippurate, and the multidrug resistance-related protein (MRP) modulator probenecid did not affect the transcellular transport of {(14)C}grepafloxacin or {(14)C}levofloxacin in the presence of cyclosporin A . The basolateral-to-apical transcellular transport of levofloxacin in the presence of cyclosporin A showed concentration-dependent saturation with an apparent Michaelis constant of 5.6 mM . In conclusion, these results suggested that basolateral-to-apical flux of quinolones was mediated by P-glycoprotein and a specific transport system distinct from organic cation and anion transporters and MRP. Antimicrob Agents Chemother, 2000 Oct, 44(10), 2905 - 7 The EmrR protein represses the Escherichia coli emrRAB multidrug resistance operon by directly binding to its promoter region; Xiong A et al.; EmrR negatively regulates the transcription of the multidrug resistance pump-encoding operon, emrRAB, by binding to its regulatory region . The binding site spans the promoter and the downstream sequence up to the transcriptional start site of the operon . Structurally unrelated drugs that induce the pump interfere with this binding. Pharm Res, 2000 Jul, 17(7), 803 - 10 Creation of polarized cells coexpressing CYP3A4, NADPH cytochrome P450 reductase and MDR1/P-glycoprotein; Brimer C et al.; PURPOSE: To develop model polarized cell systems expressing cytochrome P4503A4 . NADPH P450 reductase, and P-glycoprotein (Pgp) . METHODS: LLC-PK1 and derivative L-MDR1 cells stably expressing Pgp, the product of the multidrug resistance gene (MDR1), were transfected stably using either a mammalian neomycin selectable expression vector (CYP3A4-Neo) or an episomal vector based on Epstein-Barr virus (CYP3A4-Hygro) . These CYP3A4 expressing cells were compared with LLC-PK1, L-MDR1, or Caco-2 cells transduced with Adenovirus-3A4 vector (Ad3A4) with or without simultaneous Adenovirus-P450 Reductase (AdRed) transduction . Cells were characterized for expression of CYP3A4 protein and CYP3A4 mediated metabolism towards midazolam and testosterone . Analysis of membrane integrity and drug transport assays were performed to determine whether infection with recombinant Ad3A4 +/- AdRed affected Pgp function . RESULTS: The rank order of optimal CYP3A4 expression and activities in LLC-PKI and L-MDR1 cells from highest to lowest was cells cotransduced with Ad3A4 plus AdRed >> Ad3A4 >>> CYP3A4-Hygro > CYP3A4-Neo . Similarly, coexpression of Ad3A4 plus AdRed led to enhanced CYP3A4 mediated metabolism in Caco-2 cells over cells with Ad3A4 alone . Incubation of transwell cultured cells expressing Ad3A4/AdRed with midazolam led to readily detectable metabolite in the medium . In microsomes from Caco-2 and LLC-PK1 cells, each co-transduced with Ad3A4/AdRed, Vmax values for testosterone 6beta-hydroxylase activity ranged from 414 to 1350 pmoles/min/mg, respectively . For either Caco-2 or LLC-MDR1 cells, TEER values and the rate of apical to basal and basal to apical transport of vinblastine or digoxin were similar in cells with and without Ad3A4/Red transduction . CONCLUSIONS: Polarized cellular systems coexpressing Ad3A4, AdRed, and the MDR1/Pgp transporter were developed and characterized . The results document the utility of these polarized model systems for simultaneous drug transport/drug metabolism studies . Since the experimental approach can be adapted to study the interplay of multiple enzyme/ transporting systems, it may find significant application as a screening tool for the pharmaceutical industry and as a more basic research tool to study the kinetics of intestinal drug bioavailability. Eur J Pharmacol, 2000 Jul 21, 400(2-3), 195 - 8 Expression and immunolocalization of multidrug resistance protein 2 in rabbit small intestine; Van Aubel RA et al.; Multidrug resistance protein 2 (MRP2) is an ATP-dependent transporter of anionic drugs and conjugates . It functions as an efflux pump in the apical membranes of liver and kidney cells, but its membrane localization in small intestine has not yet been defined . The present study demonstrates exclusive localization of Mrp2 to the brush-border (apical) membrane of villi, decreasing in intensity from the villus tip to the crypts . In immunoblot analysis of crude membranes of various rabbit tissues, Mrp2 was only found in small intestine, kidney and liver . These results are in-line with the supposed function of Mrp2 in drug excretion. Cancer Res, 2000 Sep 1, 60(17), 4779 - 84 Transport of amphipathic anions by human multidrug resistance protein 3; Zeng H et al.; The multidrug resistance-associated protein 1 (MRP1) and the canalicular multispecific organic anion transporter (cMOAT or MRP2) are ATP-binding cassette transporters that confer resistance to some anticancer drugs and efflux glutathione and glucuronate conjugates from the cell . The MRP subfamily of ABC transporters, however, contains at least four other members of which MRP3 (MOAT-D) bears the closest structural resemblance to MRP1 . Although transfection studies have established that human MRP3 confers increased resistance to several anticancer agents, neither the substrate selectivity nor physiological functions of this transporter have been determined . Here we report the results of investigations of the in vitro transport properties of cloned human MRP3 using membrane vesicles prepared from MRP3-transfected HEK293 cells . It is shown that the expression of MRP3 is specifically associated with enhancement of the MgATP-dependent transport into membrane vesicles of the glucuronide estradiol 17-beta-D-glucuronide (E(2)17betaG), the glutathione conjugates 2,4-dinitrophenyl S-glutathione (DNP-SG) and leukotriene C4 (LTC4), the antimetabolite methotrexate, and the bile acid glycocholate . DNP-SG, LTC4, and E(2)17betaG are transported at moderate affinity and low capacity with Km and Vmax values of 5.7 +/- 1.7 microM and 3.8 +/- 0.1 pmol/mg/min, 5.3 +/- 2.6 microM and 20.2 +/- 5.9 pmol/mg/min, and 25.6 +/- 5.4 microM and 75.6 +/- 5.9 pmol/mg/min, respectively . Methotrexate and glycocholate are transported at low affinity and high capacity with Km and Vmax values of 776 +/- 319 microM and 288 +/- 54 pmol/mg/min and 248 +/- 113 microM and 183 +/- 34 pmol/mg/min, respectively . On the basis of these findings, the osmotic dependence of the transport measured and its inability to transport taurocholate, MRP3, like MRP1 and cMOAT, is concluded to be competent in the transport of glutathione S-conjugates, glucuronides, and methotrexate, albeit at low to moderate affinity . In contrast to MRP1, cMOAT, and all other characterized mammalian ABC transporters, however, MRP3 is active in the transport of the monoanionic human bile constituent glycocholate. Cancer Res, 2000 Sep 1, 60(17), 4761 - 6 Transactivation of the multidrug resistance 1 gene by T-cell factor 4/beta-catenin complex in early colorectal carcinogenesis; Yamada T et al.; The mutational inactivation of a tumor suppressor gene, adenomatous polyposis coli (APC), results in the accumulation of cytoplasmic beta-catenin protein and the activation of T-cell factor (TCF)/lymphoid enhancer factor transcriptional factors . A colorectal carcinoma cell line, DLD-1, was engineered to suppress transactivation by the TCF4/beta-catenin complex in a dominant-negative manner under the strict control of the tetracycline regulatory system . A large-scale comparison of the expression profiles, using two-color fluorescence hybridization of cDNA microarray, led to the identification of MDR1 as a target gene of the TCF4/beta-catenin complex . Luciferase reporter and gel retardation assays revealed the TCF4/beta-catenin responsive elements in the promoter of the human MDR1 gene . Corresponding to the accumulation of beta-catenin, expression of the MDR1 gene product was steadily up-regulated in adenomas and adenocarcinomas of 10 patients with familial adenomatous polyposis . In combination with cell proliferative activities of c-myc and cyclin D1, MDR1 may initiate colorectal tumorigenesis by suppressing cell death pathways programmed in intestinal epithelial cells. J Clin Oncol, 2000 Sep 15, 18(18), 3211 - 20 Soft tissue leiomyosarcomas and malignant gastrointestinal stromal tumors: differences in clinical outcome and expression of multidrug resistance proteins; Plaat BE et al.; PURPOSE: Several studies have reported clinical behavior and chemotherapy resistance in leiomyosarcomas, but these studies did not differentiate between soft tissue leiomyosarcomas (LMS) and malignant gastrointestinal stromal tumors (GIST) . Multidrug resistance (MDR) has been associated with the expression of P-glycoprotein (P-gp), multidrug resistance protein (MRP(1)), and lung resistance protein (LRP) . The aim of the present study was to compare LMS and GIST with respect to clinical outcome and MDR parameters . PATIENTS AND METHODS: Clinical outcome was evaluated in 29 patients with a primary deep-seated LMS and 26 patients with a primary malignant GIST . Paraffin-embedded material, available for 26 patients with LMS and 25 with GIST, was used for immunohistochemical detection of P-gp, MRP(1), LRP, and c-kit . RESULTS: Mean overall survival (OS) was 72 months for LMS patients and 31 months for GIST patients (P: <.05) . Metastases occurred in 16 (59%) of 27 assessable LMS patients and in 10 (56%) of 18 assessable GIST patients . LMS predominantly metastasized to the lungs (14 of 16 patients), whereas GIST tended to spread to the liver (five of 10 patients) and the abdominal cavity (three of 10 patients; P: <.001) . P-gp and MRP(1) expression was more pronounced in GIST than in LMS (P: <.05): the mean percentage of P-gp expressing cells was 13.4% in patients with LMS and 38.4% in patients with GIST, and the mean percentage MRP(1) expressing cells was 13.3% in patients with LMS and 35.4% in patients with GIST . LRP expression did not differ between LMS and GIST . c-kit was expressed in 5% of the LMS patients and in 68% of the GIST patients . CONCLUSION: LMS patients have a better survival than GIST patients, and the metastatic pattern is different . Expression of MDR proteins in LMS is less pronounced than in GIST. Int J Tuberc Lung Dis, 2000 Sep, 4(9), 853 - 9 A one-year prospective study (1994-1995) for a first evaluation of tuberculosis transmission in French prisons; Hanau-Bercot B et al.; SETTING: Ten correctional facilities in Paris, including suburbs . OBJECTIVE: To prospectively determine the incidence of tuberculosis (TB) in prisons during a one-year period and to trace the transmission of tuberculosis by restriction fragment length polymorphism (RFLP) analysis of Mycobacterium tuberculosis strains from inmates . RESULTS: Of 93 cases of tuberculosis observed, 50 were culture-confirmed . The incidence of tuberculosis in correctional facilities was 215 cases per 100,000 inmates . A high turnover of inmates was observed . All patients were male, and a quarter had been homeless . Seventy-two per cent were diagnosed with pulmonary tuberculosis . Several severe cases of TB were observed, including three of tuberculous meningitis . No multidrug-resistant strains were noted . RFLP analysis (n = 24) revealed 22 distinct patterns which made up two clusters . Epidemiological investigation did not show direct tuberculosis transmission, which was, however, probable for one cluster . CONCLUSION: Independently of incarceration, prison inmates run a higher risk of developing active tuberculosis than the general population, which might be the main reason for the high incidence of tuberculosis observed in prisons . However, some cases of transmission may occur inside prisons. Int J Tuberc Lung Dis, 2000 Sep, 4(9), 832 - 8 Primary and acquired drug resistance in Polish tuberculosis patients: results of a study of the national drug resistance surveillance programme; Zwolska Z et al.; OBJECTIVE: To determine the prevalence and patterns of primary and acquired drug resistance among Mycobacterium tuberculosis isolates recovered from tuberculosis patients in Poland . DESIGN: In a prospective survey, M . tuberculosis strains were collected from 3970 tuberculosis patients (2976 newly diagnosed cases and 994 previously treated patients) bacteriologically confirmed by culture between November 1996 and October 1997 . METHODS: Drug susceptibility testing to isoniazid (INH), streptomycin, ethambutol and rifampicin (RMP) was performed on Lowenstein-Jensen medium according to the proportion method and/or using the radiometric Bactec 460 TB system . RESULTS AND CONCLUSION: The male to female ratio was 2.61:1 . The patients were aged between 6 and 82 years, with 86% of males and 77% of females aged over 35 years . Primary resistance to any drug was found in 3.6% of new patients; any INH resistance was 2.6%, any RMP resistance was 0.7%, and multidrug resistance (to INH and RMP {MDR}) was 0.6% . In previously treated cases, resistance to any drug was 17.0%, any INH resistance 14.1%, any RMP resistance 7.8%, and MDR 7.0% . Drug-resistant tuberculosis does not present a big problem in Poland; primary drug resistance has been monitored since 1960 with decreasing frequency, and rates remain at the same level as 20 years ago . Studies such as this should be conducted regularly to monitor drug resistance in Poland in order to effectively manage national tuberculosis control efforts. Biomaterials, 2000 Nov, 21(21), 2203 - 10 Chronic exposure of human ovarian carcinoma cells to free or HPMA copolymer-bound mesochlorin e6 does not induce P-glycoprotein-mediated multidrug resistance; Tijerina M et al.; The acquisition of multidrug resistance in human ovarian carcinoma A2780 cells was investigated after chronic exposure to free mesochlorin e6 monoethylenediamine (Mce6) and N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-bound Mce6 (P(GG)-Mce6) . The dose that inhibits growth by 50% (IC50) was determined for free Mce6 (2.09 +/- 0.32 microM) and P(GG)-Mce6 (204.15 +/- 28.97 microM) to utilize similar effective doses of drug . A total of 14 drug exposures were performed over a period of 78 days . Cells were characterized by IC50 dose, MDR1 gene expression and anti-human P-glycoprotein (P-gp) antibody binding after each drug exposure . At the conclusion of the experiment, neither the A2780 cells habitually exposed to free Mce6 or P(GG)-Mce6 were significantly different than the control A2780 cells indicating cells did not acquire a MDR phenotype . The doxorubicin (DOX)-resistant A2780/AD cells served as a positive control. Neoplasma, 2000, 47(2), 100 - 6 Cytotoxic activity of several unrelated drugs on L1210 mouse leukemic cell sublines with P-glycoprotein (PGP) mediated multidrug resistance (MDR) phenotype . A QSAR study; Breier A et al.; L1210/VCR-1 and L1210/VCR-2 cell lines are multidrug resistant (MDR) sublines obtained by adaptation of mouse leukemic cell line L1210 to vincristine and, the development of MDR in these cell lines has been found to be associated with an overexpression of P-glycoprotein (PGP) . In the present work we studied the relationship between the structure of 15 cytotoxic active substances (drugs) and their cytotoxicities on L1210/VCR-1 and L1210/VCR-2 resistant cell lines . The resistance of these MDR cells to the respective drugs was expressed as the ratio of IC50 values obtained for resistant and sensitive cells . These values of resistance were correlated with the following physico-chemical constants of the test substances: binding energy, Ebind; total energy of the molecule, Esum; aromaticity, Kpi; molecular weight, Mw; acidobasic constant, pKa; partition coefficient in water/octanol two phase system, log(p) . It has been found that according to the cytotoxic effects the tested drugs may be divided into three groups: (i) drugs with higher cytotoxicity to the resistant cell lines as to sensitive cells (collateral hypersensitivity); (ii) drugs exhibiting approximately similar effects on sensitive and resistant cell lines; (iii) drugs with weaker cytotoxicity to resistant cells than to sensitive cells . No direct correlations with any physico-chemical constant described above could be established for cell resistance to the drug studied . However, resistance values could be fitted by multiple exponential regression with all described physico-chemical constants implied as six independent variables . The latter procedure made us to conclude that the ability of a drug to be a substrate for PGP is connected with its fulfilling the following criteria: (i) flexible structure of its molecule; (ii) molecular weight lower than approximately 1,300 g/mol; (iii) nonprotonized character at pH 7.0. AIDS, 2000 Aug 18, 14(12), 1767 - 74 Virological and immunological characteristics of HIV treatment failure; Kaufmann D et al.; BACKGROUND: Resistance to antiretroviral treatment is prevalent . There is limited knowledge of the determinants of disease evolution in subjects infected with multidrug-resistant HIV (MDR-HIV) . METHODS: Infectivity, replication, chemokine receptor usage, and env, gag, protease and reverse transcriptase sequence analysis was performed for MDR-HIV isolates from 14 HIV-infected individuals and compared to wild-type HIV isolates from individuals naive to antiretroviral treatment . Expression of CD45RO/RA, Ki67 and interferon-gamma and CD4 proliferative response to various antigens was determined for individuals infected with MDR-HIV and compared to that in individuals with optimal suppression of viral replication . RESULTS: Infectivity and replication are diminished for various MDR-HIV isolates, usually in the context of an increase in CD4 and CD4+CD45RA+ T-cell counts . However, a number of MDR-HIV isolates are associated with high in vivo viraemia and pronounced immunosuppression, and display in vitro levels of infectivity and replication comparable to those of wild-type strains . No specific genetic sequence or chemokine receptor usage predicted the fitness of an MDR isolate . CONCLUSIONS: Despite the biological diversity of resistant viruses and the range of host responses observed, our descriptive analysis indicates that viral factors play a role in determining the degree of immune damage observed in the context of MDR-HIV infection. Acta Med Okayama, 2000 Aug, 54(4), 139 - 45 Factors influencing response to treatment of pulmonary tuberculosis; Hiyama J et al.; We analyzed 150 patients with pulmonary tuberculosis from 1990 to 1996 (i) to evaluate the frequency of drug resistance, (ii) to elucidate factors influencing the response to chemotherapy, and (iii) to attempt to improve the therapeutic approach . Multidrug-resistant tuberculosis strains were not found . By univariate analysis, there were 8 factors associated with an increased sputum conversion time: male gender, prior treatment, complications, progressive chest radiographic findings, a high Ziehl-Neelsen stain score, lymphocytopenia, a high erythrocyte sedimentation rate (ESR), and hypoproteinemia . Complications, prior treatment, a high Ziehl-Neelsen stain score, and a high ESR were independent predictive factors in a Cox proportional hazard model . Recursive partitioning and amalgamation (RPA) defined 3 subgroups that responded to treatment . In order to reduce the time to sputum conversion, poor responders according to the RPA should be treated with a 4-drug regimen containing pyrazinamide. Planta Med, 2000 Aug, 66(6), 531 - 6 Leishmanicidal, antiplasmodial and cytotoxic activity of indole alkaloids from Corynanthe pachyceras; Staerk D et al.; Five indole alkaloids, corynantheidine, corynantheine, dihydrocorynantheine, alpha-yohimbine and corynanthine were isolated from bark of Corynanthe pachyceras K . Schum . (Rubiaceae) . The structures were established by spectroscopic methods, including previously unreported assignment of all 1H-NMR resonances by COSY and NOESY experiments . These and related alkaloids showed pronounced activity against Leishmania major promastigotes (IC50 at the micromolar level) but no significant in vitro antiplasmodial activity (against chloroquine-sensitive Plasmodium falciparum) . Cytotoxicity assessed with drug sensitive KB-3-1 and multidrug-resistant KB-V1 cell lines was low; the alkaloids are apparently not substrates for the P-glycoprotein (P-170) efflux pump. Epidemiol Infect, 2000 Jun, 124(3), 523 - 8 Drug resistance rates of Mycobacterium tuberculosis strains in Austria between 1995 and 1998 and molecular typing of multidrug-resistant isolates . The Austrian Drug Resistant Tuberculosis Study Group; Stauffer F et al.; In this study the drug resistance pattern of 3559 Mycobacterium tuberculosis strains isolated in Austria between 1995 and 98 was evaluated . Of these strains, 165 (4.6%) were resistant to one or more drugs, 113 (3.2%) to one of the tested drugs and 53 (1.5%) to two or more drugs . Monodrug resistance was observed most often to isoniazid (56 strains), followed by streptomycin (44 strains) . Resistance to rifampicin or ethambutol alone was rarely seen (12 strains and 1 strain, respectively) . Of the 53 strains resistant to 2 or more drugs, 25 were resistant to isoniazid and streptomycin, while 17 were multidrug resistant . Molecular typing revealed a large diversity among the multidrug-resistant strains. Probl Tuberk, 2000, (4), 24 - 6 {Effectiveness of the surgical treatment of patients with pulmonary tuberculosis and multidrug resistance of its causative agent}; Shaikhaev AIa et al.; In 1996-1998, the Central Institute of Tuberculosis, Russian Academy of Medical Sciences performed more than 600 operations . Of them 90 (15%) patients isolated mycobacteria . The drug resistance of M . tuberculosis was found in 69 (76.7%) patients . In 60.9% of cases, the resistance of M . tuberculosis to isoniazid and rifampicin was concurrently accompanied by that to one (21.4%), two (61.0%), and even 3 (14.8%) tuberculostatics . Removal of the lung or its remnants in the extrapleural layer was most common (67.7%); thoracic cavernomyoplastic operations were made in 17.4% of cases, and partial resections accounted for only 13% . Postoperative complications were more frequently encountered in patients with drug-resistant tuberculosis than in controls (6.7%) . Among them, tuberculosis progression and empyema were prevalent (13%) . The clinical efficiency and duration of surgical treatment were directly related to the rates of progression and to the magnitude of drug-resistance of Mycobacteria. J Biol Chem, 2000 Dec 1, 275(48), 37347 - 56 Multiple signals from dysfunctional mitochondria activate the pleiotropic drug resistance pathway in Saccharomyces cerevisiae; Hallstrom TC et al.; Multiple or pleiotropic drug resistance most often occurs in Saccharomyces cerevisiae due to substitution mutations within the Cys(6)-Zn(II) transcription factors Pdr1p and Pdr3p . These dominant transcriptional regulatory proteins cause elevated drug resistance and overexpression of the ATP-binding cassette transporter-encoding gene, PDR5 . We have carried out a genetic screen to identify negative regulators of PDR5 expression and found that loss of the mitochondrial genome (rho(o) cells) causes up-regulation of Pdr3p but not Pdr1p function . Additionally, loss of the mitochondrial inner membrane protein Oxa1p generates a signal that results in increased Pdr3p activity . Both of these mitochondrial defects lead to increased expression of the PDR3 structural gene . Importantly, the signaling pathway used to enhance Pdr3p function in rho(o) cells is not the same as in oxa1 cells . Loss of previously described nuclear-mitochondrial signaling genes like RTG1 reduce the level of PDR5 expression and drug resistance seen in rho(o) cells but has no effect on oxa1-induced phenotypes . These data uncover a new regulatory pathway connecting expression of multidrug resistance genes with mitochondrial function. Int J Hematol, 2000 Jul, 72(1), 20 - 7 Current status and future issues in the treatment of HIV-1 infection; Matsushita S; Over the past 5 years, advances in human immunodeficiency virus type 1 (HIV-1) clinical research and data on the effectiveness of potent combination therapy have substantially influenced the overall perspective of the long-term management of HIV-1 disease . It is now generally accepted that the benefits of mono- and bio-therapy for HIV-1 infection are only transient owing mainly to antiviral-drug resistance . To obtain continued benefit from antiviral therapy, current guidelines recommend at least triple-drug combinations, or so-called highly active antiretroviral therapy (HAART) . In Japan, 13 antiretroviral agents are currently available for combination therapy . Ten of them have been approved for clinical use in the past 3 years . Following the introduction of HAART, marked decreases in AIDS-related morbidity and mortality have been observed . However, in some patients, HAART can be problematic, either because it is difficult for the patient to remain compliant or because previous suboptimum therapies have limited the choice of drugs . For compliant, drug-naive patients, HAART should offer long-term virus suppression, when changing from first- to second- to third-line HAART following drug failure . Long-term treatment might ultimately result in multidrug resistance, leaving few options for salvage therapy . HIV-1 drug resistance testing to enable salvage therapy and the development of new drugs and immunotherapeutic agents to allow new options will therefore remain priorities in HIV-1 research. Leuk Res, 2000 Sep, 24(9), 769 - 74 Identification of the subcellular localization of daunorubicin in multidrug-resistant K562 cell line; Gong Y et al.; We examined the subcellular distribution of daunorubicin (DNR) in resistant K562 cell line which overexpress the P-glycoprotein by confocal laser scanning microscopy . Three fluorescent probes - Rhodamine123, neutral red, NBD-ceramide, which stain the mitochondria, lysosomes, Golgi apparatus respectively, were used to identify the nature of the subcellular compartment sequestering daunorubicin . In sensitive k562 cell line, nuclear and cytoplasmic DNR fluorescence was intense and diffuse . In contrast, resistant K562 cell line showed a different DNR distribution . A bright fluorescence signal was located in the perinuclear region and peripheral plasma, the nucleus and other cytoplasmic region appear as empty, as suggested by the distribution of fluorescent probe Rhodamine123 specifically for mitochondria . Verapamil, an effective resistance modulator in P-glycoprotein MDR cells, restored the DNR distribution closer to that in the parent cells . Golgic inhibitor brefeldin A and lysosomotropic agent chloroquine had little effect on drug sequestration . Our studies demonstrate that daunorubicin may be sequestered in mitochondrial compartment in the resistant cells and P-glycoprotein plays an important role on mediating DNR transport. J Biol Chem, 2000 Dec 15, 275(50), 39617 - 24 Identification of basic residues involved in drug export function of human multidrug resistance-associated protein 2; Ryu S et al.; Multidrurg resistance-associated protein 2 (MRP2)/canalicular multispecific organic anion transporter (cMOAT) is involved in the ATP-dependent export of organic anions across the bile canalicular membrane . To identify functional amino acid residues that play essential roles in the substrate transport, each of 13 basic residues around transmembrane regions (TMs) 6-17 were replaced with alanine . Wild type and mutant proteins were expressed in COS-7 cells, and the transport activity was measured as the excretion of glutathione-methylfluorescein . Four mutants, K324A (TM6), K483A (TM9), R1210A (TM16), and R1257A (TM17), showed decreased transport activity, and another mutant, K578A (TM11), showed decreased protein expression . These five mutants were normally delivered to the cell surface similar to the other fully active mutants and wild type MRP2 . The importance of TM6, TM16, and TM17 in the transport function of MRP2 is consistent with the previous observation indicating the importance of the corresponding TM1, TM11, and TM12 on P-glycoprotein (Loo, T . W., and Clarke, D . M . (1999) J . Biol . Chem . 274, 35388-35392) . Another observation that MRP2 inhibitor, cyclosporine A, failed to inhibit R1230A specifically, indicated the existence of its binding site within TM16. Am J Vet Res, 2000 Sep, 61(9), 1122 - 7 Molecular analysis of multidrug resistance in feline lymphoma cells; Okai Y et al.; OBJECTIVE: To evaluate the mechanism of multidrug resistance in feline lymphoma cell lines . SAMPLE POPULATION: A feline lymphoma cell line (FT-1) and its adriamycin (ADM)-resistant subline (FT-1/ADM) . PROCEDURES: The FT-1 cell line was cultivated in the presence of a gradually increasing concentration of ADM to generate its ADM-resistant subline (FT-1/ADM) . Susceptibility of cells from the parental FT-1 cell line and the FT-1/ADM subline to antineoplastic drugs was determined . From the complementary DNA (cDNA) template of FT-1/ADM cells, feline MDR1 cDNA was amplified by use of polymerase chain reaction (PCR) and sequenced . Reverse transcription (RT)-PCR and Western blot analyses were performed to assess expression of the MDR1 gene and P-glycoprotein (P-gp) in FT-1/ADM cells, compared with that in FT-1 cells . RESULTS: A drug sensitivity assay revealed that FT-1/ADM cells were much more resistant to ADM and vincristine than the parental FT-1 cells . The feline MDR7 cDNA amplified by use of PCR was 3,489 base pairs long, corresponding to approximately 90% of the whole open reading frame of human MDR1 cDNA; its amino acid sequence was 91.5, 87.0, and 79.4% identical to that of human MDR1, mouse mdr1a, and mdr1b cDNA, respectively . By RT-PCR analysis, expression of MDR1 messenger RNA was clearly detected in FT-1/ADM cells but not in the parental FT-1 cells . Western blot analysis also revealed the expression of P-gp encoded by the MDR1 gene in FT-1/ADM cells but not in FT-1 cells . CONCLUSIONS: The basic structure of the feline MDR1 gene was essentially the same as that of multidrug-resistance genes of other species . Expression of P-gp appeared to be one of the mechanisms responsible for the development of multidrug resistance in feline lymphoma cell lines in vitro. Curr Opin Oncol, 2000 Sep, 12(5), 450 - 8 Multidrug resistance transporters and modulation; Tan B et al.; Multidrug resistance (MDR), whereby tumor cells simultaneously possess intrinsic or acquired cross-resistance to diverse chemotherapeutic agents, hampers the effective treatment of cancer . Molecular investigations in MDR resulted in the isolation and characterization of genes coding for several proteins associated with MDR, including P-glycoprotein (P-gp), the multidrug resistance associated protein (MRP1), the lung resistance protein (LRP), and, more recently, the breast cancer resistance protein (BCRP) . These transmembrane proteins cause MDR either by decreasing the total intracellular retention of drugs or redistributing intracellular accumulation of drugs away from target organelles . These proteins are expressed at varying degrees in different neoplasms, including the AIDS-associated non-Hodgkin lymphoma and Kaposi sarcoma and are generally associated with poor prognosis . Several MDR-reversing agents are in various stages of clinical development . First-generation modulators such as verapamil, quinidine, and cyclosporin required high doses of drugs to reverse MDR and were associated with unacceptable toxicities . Second- and third-generation MDR inhibitors include PSC 833, GF120918, VX-710, and LY335979, among others . Limitations to the use of these modulators include multiple and redundant cellular mechanisms of resistance, alterations in pharmacokinetics of cytotoxic agents, and clinical toxicities . Studies to validate the role of MDR reversal in the treatment of various malignancies are underway . A potential use of these agents may be to enhance intestinal drug absorption and increase drug penetration to biologically important protective barriers, such as the blood-brain, blood-cerebrospinal fluid, and the maternal-fetal barriers . The use of MDR modulators with drugs such as the antiviral protease inhibitors and cytotoxics may enhance drug accumulation in sanctuary sites that are traditionally impenetrable to these agents. Trans R Soc Trop Med Hyg, 2000 May-Jun, 94(3), 271 - 5 RFLP patterns and risk factors for recent tuberculosis transmission among hospitalized tuberculosis patients in Rio de Janeiro, Brazil; Fandinho FC et al.; Isolates of Mycobacterium tuberculosis from 120 tuberculosis patients seen in the 12 months ending September 1994 at 2 tertiary-care centres in Rio de Janeiro were characterized by IS6110 restriction fragment length polymorphism (RFLP) analysis . Ninety-seven patients (81%) had isolates with unique RFLP patterns, while 23 patients (19%) had isolates that belonged to 11 different RFLP cluster patterns . The strains from the latter patients were distributed among 1 group of 3 patients and 10 groups of 2 patients each . The cluster-pattern strains were not associated with gender, age, HIV infection, type of residence, living in shelter, homelessness or previous history of tuberculosis . However, clustering was strongly associated with multidrug resistance (P = 0.006) . These data suggest that recent exogenous transmission may be important for the development of new cases of multidrug-resistant disease in patients attending tertiary-care centres in Rio de Janeiro, Brazil. Cesk Patol, 2000 Jul, 36(3), 111 - 5 {Biological characteristics of multiple myeloma}; Dusek J et al.; On a series of thirty trephine bone marrow biopsies from patients with multiple myeloma, the authors evaluated expression of markers of cell proliferation or of its blockade (Ki-67, PCNA, topoisomerase IIa, cyclin D-1, AgNOR, and p27kip1) and markers indicating multidrug resistance (P-170 and Bcl-2) . Expression of Ki-67 and of topoisomerase IIa was unfrequent . Marked positivity of PCNA was expressed in about one third of cases, negative staining was exceptional . No expression of cyclin D-1 was noted . Positivity of p27kip1 was frequent . P-170 was demonstrated in a small number of cases, Bcl-2 was strongly positive in most cases . The results characterise multiple myeloma as a tumour with low proliferation rate and, simultaneously, with high resistance to apoptosis. Acta Cient Venez, 2000, 51(1), 45 - 52 {Multidrug or pleiotropic resistance}; Arvelo F et al.; The resistance to cytotoxic drugs represents a major obstacle to successful cancer therapy . The intrinsic resistance of tumoral cells is one of major causes of treatment failure . The overexpression of a membrane associated glycoprotein, P-glycoprotein, in tumoral cell lines, resistant to a wide range of drugs, permitted the description of a multidrug resistance (MDR) phenotype . This P-glycoprotein, which appears to play a role in drug efflux is encoded by the mdr1 gene in humans . The frequent mdr1 gene overexpression in clinically resistant tumours suggest that this gene may be the cause of treatment failure in human cancer . This review summarizes recent developments in this area, which suggest that both the activity of the pump and its genetic regulation are potential targets for new anticancer therapies. Cancer Lett, 2000 Oct 16, 159(1), 95 - 101 Establishment and characterization of 5-fluorouracil-resistant gastric cancer cells; Chung YM et al.; Two 5-fluorouracil (5-FU)-resistant cell lines from a Korean gastric cancer cell line were established by incubation of the cells with increasing concentration of 5-FU, and the resultant cell lines showed an over 800-fold increased resistance to 5-FU . To identify the mechanism of 5-FU resistance, the expressions of genes involved in 5-FU metabolism were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) . Expressions of orotate phosphoribosyltransferase (OPRT), thymidine phosphorylase (TP), and uridine phosphorylase (UP) were significantly downregulated in these cell lines, resulting in low incorporation of 5-FU into nucleic acids . In contrast, an increased expression of thymidine kinase (TK) was observed in 5-FU-resistant cells . These results strongly indicate that blocking of 5-FU incorporation into nucleic acids and TK overexpression may play a major role in 5-FU resistance in these cells . Interestingly, these cell lines showed cross-resistance to paclitaxel, cisplatin, and doxorubicin, suggesting that other factors such as HSP27 and Mn-SOD could be also involved in the mechanism of multidrug resistance in these cell lines. Curr Pharm Des, 2000 Nov, 6(16), 1653 - 68 Monitoring interactions at ATP-dependent drug efflux pumps; Hendrikse NH; Chemotherapeutic treatment of cancer patients is often unsuccessful, due to the involvement of various mechanisms, leading to multidrug resistance (MDR) . In this review, I describe the mechanisms involved in MDR . Furthermore, results obtained by imaging of P-glycoprotein (P-gp) and the multidrug resistance associated protein (MRP) are reviewed . Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are unique techniques to study P-gp- and MRP-mediated transport . The radiopharmaceutical (99m)Tc-sestamibi is a substrate for both P-gp and MRP . This tracer has been used for tumor imaging in clinical studies, and to visualize blockade of P-gp mediated transport after modulation of the P-gp pump . Other (99m)Tc-radiopharmaceuticals such as (99m)Tc- tetrofosmin and several (99m)Tc-Q-complexes are also substrates for P-gp . Until now, for these compounds only results from in vitro and animal studies are available . For quantification of P-gp mediated transport with PET in vivo, several agents, such as {(11)C}colchicine, {(11)C}verapamil and {(11)C}daunorubicin have been evaluated . In vivo results suggest that these radiopharmaceuticals can be used to image P-gp function in tumors . (124)I and (76)Br radiolabeled doxorubicin analogues are also useful to examine P-gp mediated transport . Leukotrienes are specific substrates for MRP . Therefore, N-{(11)C}acetyl-leukotriene E4 provides the opportunity to study MRP function non-invasively . Results obtained with this radiopharmaceutical in MRP(2) mutated GY/TR- rats indicate visualization of MRP-mediated transport . This tracer enables to study MRP transport function abnormalities in vivo such as in Dubin-Johnson patients, who are MRP(2) gene deficient . In conclusion, it is feasible to study the functionality of MDR transporters in vivo, both with SPECT and with PET . Such imaging techniques may become an important factor in the development of novel chemotherapeutic drugs. Biochem Biophys Res Commun, 2000 Sep 7, 275(3), 795 - 803 Structure-activity studies of verapamil analogs that modulate transport of leukotriene C(4) and reduced glutathione by multidrug resistance protein MRP1; Loe DW et al.; The 190-kDa multidrug resistance protein MRP1 is an ATP-binding cassette protein that confers resistance to multiple antineoplastic agents and actively transports conjugated organic anions . We have previously shown that MRP1-mediated GSH transport is stimulated by verapamil but transport of verapamil in the presence or absence of GSH is not observed . We have now examined 20 sulfur-containing verapamil analogs for their ability to inhibit MRP1-mediated leukotriene C(4) (LTC(4)) transport and stimulate GSH uptake into inside-out membrane vesicles . All of the derivatives were poor inhibitors of LTC(4) uptake . However, the inhibitory potency of the more lipophilic dithiane compounds could be enhanced by coincubation with GSH whereas this was not the case for the more hydrophilic dithiane tetraoxides . The dithiane derivatives stimulated GSH transport whereas, with one exception, the dithiane tetraoxides did not . One pair of dithiane stereoisomers differed significantly in their ability to stimulate GSH transport although their ability to inhibit LTC(4) uptake in the presence of GSH was comparable . Our findings indicate that the GSH transport activity of MRP1 can be dissociated from its conjugated organic anion transport activity . Brain Res, 2000 Sep 8, 876(1-2), 148 - 53 Expression of various multidrug resistance-associated protein (MRP) homologues in brain microvessel endothelial cells; Zhang Y et al.; Multidrug resistance-associated protein (MRP) actively transports a broad range of anionic compounds out of the cell . To date, six different homologues of MRP (i.e . MRP1-MRP6) have been identified . The current study examines the expression of the various MRP homologues in both primary cultured bovine brain microvessel endothelial cells (BBMEC) and the capillary-enriched fraction from bovine brain homogenates . RT-PCR analysis demonstrated the presence of MRP1, MRP4, MRP5 and MRP6 in both BBMEC and the capillary-enriched fractions of brain homogenates . While low levels of MRP3 were detected in the BBMEC, it was not observed in the capillary-enriched fraction . In addition, RT-PCR and Western blot studies indicated an absence of MRP2 expression in both blood-brain barrier preparations . The presence of several different MRP homologues in the brain microvessel endothelial cells may be important in controlling the permeability of the blood-brain barrier to organic anions. Br J Clin Pharmacol, 2000 Sep, 50(3), 237 - 46 Effect of P-glycoprotein modulation on the clinical pharmacokinetics and adverse effects of morphine; Drewe J et al.; AIMS: To investigate the effect of acute P-glycoprotein inhibition by the multidrug-resistance (MDR) modulator valspodar (SDZ PSC 833; PSC) on the pharmacokinetics, and potentially adverse pharmacodynamic effects of morphine, and its principal pharmacologically active metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) . METHODS: In a double-blind, three-way crossover study, the pharmacokinetic and potentially adverse pharmacodynamic effects (reaction time, transcutaneous PCO2, blood pressure) of morphine were compared with and without acute inhibition of P-glycoprotein by PSC . The effects of PSC alone were also evaluated . The study was performed in 18 healthy male volunteers and pharmacodynamic effects analysed by measuring the area under the effect (AUE) curve . 150 mg PSC (or its placebo) was given as an i.v . infusion over 2 h . With the expected inhibition of Pgp 1 h after starting PSC infusion, 7.5 morphine HCl (or its placebo) was infused over 2 h . RESULTS: The infusion of PSC resulted in blood concentrations expected to inhibit Pgp mediated transport . While the pharmacokinetics of plasma morphine and M6G . were unaffected there was a small but statistically significant increase in the AUC and Cmax of M3G (11.8 and 8.3%, respectively) . The t(1/2) and tmax were unaffected . The pharmacokinetic parameters of PSC were not affected by coadministration with morphine . PSC did not significantly affect the adverse events of morphine, as assessed by spontaneous reporting . Compared with PSC alone, morphine elicited an increase in reaction time (Emax 48 ms, compared with the predose absolute reaction time of 644 ms), which was not detected by the alertness-drowsiness score, indicating only slight sedation . There was a significant decrease in systolic blood pressure (Emin -9 mm Hg), and a trend for a fall in diastolic blood pressure (Emin -14.5 mm Hg) and respiratory rate (Emin -1.8 breath x min(-1)) . For all these parameters, the effects of PSC/morphine were similar to that of PSC alone, suggesting some attenuation of morphine's effect . In contrast, morphine caused a significant increase in PCO2 (Emax 0.69 kPa) compared to PSC alone, indicating slight respiratory depression . This increase was similar to that of the PSC/morphine combination . CONCLUSIONS: Acute inhibition of P-glycoprotein by PSC in this setting does not affect the pharmacokinetic or safety-related pharmacodynamic profile of morphine in a clinically significant manner. Br J Cancer, 2000 Oct, 83(7), 921 - 7 Drug resistance features and S-phase fraction as possible determinants for drug response in a panel of human ovarian cancer xenografts; Kolfschoten GM et al.; Multidrug resistance (MDR) and more specifically the expression of P-glycoprotein (Pgp) have been studied extensively in vitro . Unfortunately, it appears that the predictive value of MDR recognized in vitro is mostly an incorrect measure to determine the responsiveness of a particular tumour in the clinic . This misunderstood or overvalued role of MDR might explain the failure of strategies to reverse Pgp function by the use of modulators in solid tumours . To obtain more insight in in vivo drug resistance we investigated a panel of 15 human ovarian cancer xenografts consisting of the most common histological subtypes known in ovarian cancer patients . The response rate to cisplatin, cyclophosphamide and doxorubicin in the xenografts resembled the results of phase II trials with these agents in ovarian cancer patients . This resemblance justifies drug resistance studies in this experimental in vivo human tumour system . We determined the expression levels of MDR 1, MRP 1, LRP and topoisomerase IIalpha mRNA by the RNase protection assay and the presence of MRP1 and LRP proteins by immunohistochemistry . The S-phase fraction was investigated as a separate parameter by flow cytometry . In none of the 15 ovarian cancer xenografts was MDR 1 expression detectable . The expression levels of MRP 1 and LRP were low to moderate and resembled the presence of the MRP1 and LRP proteins . There was a weak, inverse relationship between the expression levels of LRP and sensitivity to cisplatin and cyclophosphamide (r = -0.44 and -0.45), but not to doxorubicin . The levels of topoisomerase IIalpha varied among the xenografts (0.73-2.66) and failed to correlate with doxorubicin resistance (r = 0.14) . The S-phase fraction, however, showed a relation with the sensitivity to cisplatin (r = 0.66) . Among the determinants studied in ovarian cancer in vivo, LRP mRNA and the S-phase fraction were the best predictive factors for drug response and most specifically for the activity of cisplatin . Br J Cancer, 2000 Oct, 83(7), 892 - 8 MDR 1 activation is the predominant resistance mechanism selected by vinblastine in MES-SA cells; Chen GK et al.; Single-step selection with vinblastine was performed in populations of the human sarcoma cell line MES-SA, to assess cellular mechanisms of resistance to the drug and mutation rates via fluctuation analysis . At a stringent selection with 20 nM vinblastine, resulting in 5-6 logs of cell killing, the mutation rate was 7 x 10(-7)per cell generation . Analysis of variance supported the hypothesis of spontaneous mutations conferring vinblastine resistance, rather than induction of adaptive response elements . Surviving clones displayed a stable multidrug resistance phenotype over a 3-month period . All propagated clones demonstrated high levels of resistance to vinblastine and paclitaxel, and lower cross-resistance to doxorubicin and etoposide . Activation of MDR 1 gene expression and P-glycoprotein function was demonstrable in all clones . No elevation was found in the expression of the mrp gene, the LRP-56 major vault protein and beta-tubulin isotypes (M40, beta4, 5beta, and beta9) in these mutants . We conclude that initial-step resistant mechanism in these vinblastine-selected mutants commonly arises from a stochastic mutation event with activation of the MDR 1 gene . Cancer Res, 2000 Aug 15, 60(16), 4403 - 11 Human acute myeloid leukemia CD34+/CD38- progenitor cells have decreased sensitivity to chemotherapy and Fas-induced apoptosis, reduced immunogenicity, and impaired dendritic cell transformation capacities; Costello RT et al.; The destruction of cells capable of initiating and maintaining leukemia challenges the treatment of human acute myeloid leukemia . Recently, CD34+/CD38- leukemia progenitors have been defined as new leukemia-initiating cells less mature than colony-forming cells . Here we show that CD34+/CD38- leukemia precursors have reduced in vitro sensitivity to daunorubicin, a major drug used in leukemia treatment, in comparison with the CD34+/CD38+ counterpart, and increased expression of multidrug resistance genes (mrp/lrp) . These precursors show lower expression of Fas/Fas-L and Fas-induced apoptosis than CD34+/CD38+ blasts . Moreover, the CD34+/CD38- leukemic subpopulation induces a weaker mixed leukocyte reaction of responding T-lymphocytes than the CD34+/CD38+ leukemic counterpart, either in a MHC-unmatched or MHC-matched settings . This weaker immunogenicity could be linked to lower expression on CD34+/CD38- leukemia precursors of major immune response molecules (MHC-DR, LFA-3, B7-1, or B7-2) than CD34+/CD38+ leukemic cells . Nonetheless, the susceptibility of the immature CD38- precursors to cytotoxicity was not different from the sensitivity of the CD38+ counterpart . Finally, CD34+/CD38- leukemia precursors, in contrast with CD38+ precursors, failed, under appropriate conditions, to differentiate into dendritic cells, a central step for antigen recognition . This is to our knowledge the first demonstration that the very immature phenotype of CD34+/CD38- leukemic progenitors confers both chemotherapy resistance and decreased capacities to induce an immune response . Because the susceptibility of the immature leukemia cells as cytotoxic targets is maintained, our data underline the importance of improving the initial steps of leukemia recognition, more particularly by defining optimal conditions of dendritic cell transformation of the very immature hematopoietic precursors. Eur Respir J, 2000 Aug, 16(2), 364 - 71 Standardization of antituberculosis drug resistance surveillance in Europe . Recommendations of a World Health Organization (WHO) and International Union Against Tuberculosis and Lung Disease (IUATLD) Working Group; Schwoebel V et al.; Surveillance of antituberculosis drug resistance is an essential tool for evaluating the quality of tuberculosis control programmes . Consensus-based recommendations on uniform reporting of antituberculosis drug resistance surveillance data in Europe have been developed by a Working Group of the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD) . Laboratories should use standardized methods for testing drug susceptibility with a quality assurance programme including national and international proficiency testing . The proportion of drug resistance, particularly resistance to isoniazid, rifampicin or both (multidrug resistance) among all definite, i.e . culture-positive, tuberculosis cases at the start of treatment is the major indicator of interest . It should be calculated separately among patients treated previously and among those who have never been treated with > or = 1 month of combined antituberculosis drugs . The Working Group recommends that, in countries in which resources allow, laboratories report drug susceptibility test results on all isolates of the Mycobacterium tuberculosis complex . Test results of the specimen at the start of treatment and clinical data from the notification should be linked using a suitable identifier . Results should be presented by calendar year and analysed by age, sex, place of birth, site of disease and sputum smear results . In countries in which a routine system cannot be organized, representative surveys or sentinel systems are possible alternatives . In some countries, the annual prevalence of multidrug-resistant tuberculosis may be estimated through a national laboratory reporting system. Eur Respir J, 2000 Aug, 16(2), 203 - 8 Results from 8 yrs of susceptibility testing of clinical Mycobacterium tuberculosis isolates in Denmark; Thomsen VO et al.; Increased rates of multidrug-resistant (MDR) tuberculosis (TB) has been reported from countries close to Denmark . This study evaluated the incidence of drug resistance in Denmark in order to determine the magnitude of the problem . Susceptibility testing was performed in isolates from 85.4% of all notified patients during 1991-1998 . Epidemiological information was retrieved from the mandatory notification forms . Total drug resistance remained largely constant, although a minor increase was observed in 1997-1998 . Monoresistance was observed in 7.3%, of the isolates . Among 3.6% polyresistant isolates, resistance to isoniazid and streptomycin accounted for 2.8%, whereas MDR accounted for 0.5% . The MDR strains displayed different restriction fragment length polymorphism (RFLP) patterns, and no matches were identified in the international MDR database . Drug resistance in untreated Danes and foreigners were 5.9% and 14.6%, respectively . Among Danes and foreigners with previous TB, 6.2% and 22.7% had drug resistance, respectively . Increased drug-resistance was found among untreated Danes aged 25-54 yrs mainly due to a single isoniazid and streptomycin-resistant RFLP-cluster . Among all patients with isoniazid and streptomycin-resistance, 77.0% had clustered strains . In conclusion, although drug resistance among untreated Danes was close to the rate estimated in good national programmes, close monitoring is needed in future years, as active transmission of isoniazid- and streptomycin-resistant Mycobacterium tuberculosis was demonstrated. Life Sci, 2000 Jul 7, 67(7), 759 - 63 Pyronaridine: an effective antimalarial against multidrug-resistant malaria; Dutta GP et al.; Pyronaridine, administered intramuscularly (im) to Swiss mice infected with the lethal multidrug-resistant Plasmodium yoelii nigeriensis, was found to exert high blood schizontocidal activity . The efficacy of doses of pyronaridine ranging from 0.625 to 30 mg (base/kg) was evaluated using a 4 day treatment schedule (drug was administered at 0, 24, 48 and 72 hrs) . It was found that doses of 2.5mg/ kg and higher protected animals completely from the lethal effects of the parasite . The same degree of protection was found when the treatment duration was reduced to 3 days . This study shows that pyronaridine is a potentially useful antimalarial drug that could be exploited for the control of multidrug-resistant malaria infection. Arch Dermatol Res, 2000 Jul, 292(7), 354 - 61 Expression and activity of P-glycoprotein in transplantable hamster melanomas; Witkowski JM et al.; In the study described here we investigated the possibility of an association between the aggressiveness of melanoma and multidrug resistance phenotype by analyzing the expression and activity of P-glycoprotein (Pgp) in two genetically related transplantable hamster melanomas--a melanotic (Ma) and an amelanotic (Ab) form --which differed in aggressiveness and metastatic potential . Flow cytometric analysis of Pgp activity (using a verapamil-sensitive rhodamine R123 exclusion test) as well as Western blotting of cellular lysates showed its preferential (although not very marked) expression in the Ab melanoma cells . The Ab melanoma cells also exhibited a higher proportion of tumor-infiltrating lymphocytes (TIL), mostly of T cell phenotype, that may have reflected a higher immunogenicity of the tumor . In conclusion, Pgp activity appeared to be associated with less-differentiated more aggressively metastasizing melanoma (the Ab variant) although its role in maintaining this phenotype remains to be established. Biol Pharm Bull, 2000 Aug, 23(8), 926 - 9 Mithramycin represses MDR1 gene expression in vitro, modulating multidrug resistance; Tagashira M et al.; The effect of an aureolic acid, mithramycin (MTM) on multidrug resistance (MDR) was investigated . At a concentration of 0.02--0.1 mg/ml (about 20--90 microM), MTM repressed MDR1 gene transcription of SBC-3/ADM, a MDR-phenotype subline derived from human small cell lung tumor . Under the same conditions, another aureolic acid, chromomycin A3, showed potent cytotoxicity . FACS analysis revealed that 5 microm MTM depleted the P-glycoprotein (Pgp) and lowered the efflux activity of SBC-3/ADM cells . Furthermore, MTM sensitized the cells against adriamycin . These results suggest that MTM would be a useful modulator of MDR induced by Pgp. Biochim Biophys Acta, 2000 Aug 31, 1481(1), 63 - 74 Two transport binding sites of P-glycoprotein are unequal yet contingent: initial rate kinetic analysis by ATP hydrolysis demonstrates intersite dependence; Wang EJ et al.; The ATP-dependent transport enzyme known as P-glycoprotein (P-gp) confers multidrug resistance (MDR) against many unrelated drugs and xenobiotics . To understand better the broad substrate specificity of the enzyme as well as the mechanism of substrate transport out of the cell, it is critical to characterize the substrate binding sites . Since approximately 1 ATP is hydrolyzed per transport event, phosphate release rate provides a steady-state kinetics assay . Notably, the substrate H33342 causes a decrease in the baseline hydrolysis of ATP (probably due to competition for transport with an endogenous membrane lipid substrate) providing an excellent tool for a comprehensive graphical kinetic analysis of the interaction of substrate pairs at the transport site(s) allowing the determination of inhibition type and hence characterization of transport binding sites . The substrate H33342 interacted with quinidine, progesterone, and propranolol in a non-competitive manner, indicating that binding of H33342 precludes active transport of these other substrates at a distinct site . Compounds such as TPP+ and verapamil, and perhaps also nicardipine, interacted with H33342 as mixed-type inhibitors . This type of interaction results from a reduced affinity at the opposing active site by a factor of alpha and sometimes a partial activity of a fraction beta . Indeed, H33342 binding caused a roughly four-fold reduced affinity for TPP+ . Using this definitive approach to inhibition kinetics, we were able to establish traits of a second transport site in P-gp . Therefore, the sites are unequal; however, the performance at one site is contingent on the other being unoccupied, and transport is also sometimes mitigated when the other site is occupied. Cancer Lett, 2000 Oct 1, 158(2), 203 - 10 Transfer of p14ARF gene in drug-resistant human breast cancer MCF-7/Adr cells inhibits proliferation and reduces doxorubicin resistance; Guo-Chang F et al.; The INK4a/ARF locus on human chromosome 9p21 encodes two tumor suppressors, p16INK4a and p14ARF, that restrain cell growth by affecting the functions of the retinoblastoma protein and p53, respectively . Overexpression of ARF results in cell cycle arrest in both G1 and G2 . To elucidate the effect of p14ARF gene on multidrug-resistant tumor cells, we transferred a p14ARF cDNA into p53-mutated MCF-7/Adr human breast cancer cells . In this report we demonstrated for the first time that p14ARF expression was able to greatly inhibit the MCF-7/Adr cell proliferation . Furthermore, p14ARF expression resulted in decrease of MDR-1 mRNA and P-glycoprotein production, which linked to the reducing resistance of MCF-7/Adr cells to doxorubicin . These results imply that drug resistance might be effectively reversed by the wild-type p14ARF expression in human breast cancer cells. Hepatology, 2000 Sep, 32(3), 556 - 62 Altered gene expression in the liver of gamma-glutamyl transpeptidase-deficient mice; Habib GM et al.; We used mice deficient in gamma-glutamyl transpeptidase (GGT) to analyze the effects of GGT deficiency and altered thiol levels on gene expression in liver . GGT-deficient mice have markedly reduced levels of glutathione (GSH), cysteine, methionine, and cysteinylglycine in liver . Steady-state RNA levels of the catalytic subunit of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme in GSH synthesis, are elevated 4-fold in these mice, while those for glutathione synthetase (GSH syn) are elevated 2-fold . RNA levels of cystathionase (cystathionine gamma-lyase), a key enzyme in the synthesis of cysteine from methionine, are elevated approximately 3.5-fold . In contrast, levels of RNA coding for multidrug resistance protein 2 (MRP2), which transports GSH into bile, are half wild-type values . We found no change in RNA levels of enzymes related to oxidative injury (CuZn and Mn superoxide dismutases {SOD}, catalase, and glutathione peroxidase) . Similarly, RNA levels of glutathione reductase and ribonucleotide reductase were unchanged . Furthermore, in contrast to previous in vitro results, methyl methanesulfonate did not induce stress-activated signal transduction as measured by c-jun phosphorylation in livers of GGT-deficient mice, despite further depletion of GSH by buthionine sulfoximine . Our findings indicate that GGT deficiency itself and/or altered thiol levels regulate expression of genes involved in GSH metabolism, but have no effect on the expression of other antioxidant genes. Pediatr Infect Dis J, 2000 Aug, 19(8), 695 - 9 Transmission of multidrug-resistant tuberculosis; Schaaf HS et al.; AIM: To compare the Mycobacterium tuberculosis isolates of adult index cases with multidrug-resistant (MDR) tuberculosis to the isolates obtained from their child contacts . PATIENTS AND METHODS: A 4-year prospective study in the Western Cape Province of South Africa . We evaluated 149 child contacts of 80 adult MDR pulmonary tuberculosis cases . This report includes those cases where a culture for M . tuberculosis was obtained from both the adult source case and the child contact . Isolates were compared by drug susceptibility pattern and restriction fragment length polymorphism analysis . RESULTS: Six adult-child pairs with cultures for M . tuberculosis were identified . Two children had contact with more than one adult tuberculosis case . One child received previous isoniazid prophylaxis . Drug susceptibility pattern and restriction fragment length polymorphism analysis were identical for five adult-child pairs . One child, with no other known source case, had a strain different from that of the identified source case, but the MDR M . tuberculosis strain with which he was infected was prevalent in the community in which he resided . All children responded well to treatment . CONCLUSION: This study confirms that most of the childhood contacts of adults with MDR tuberculosis are likely to be infected by these MDR source cases despite their exposure to other drug-susceptible adults with tuberculosis in some instances . Child contacts of adults with MDR tuberculosis should be treated according to the drug susceptibility patterns of the likely source cases' M . tuberculosis strains unless their own strain's susceptibility testing indicates otherwise . Contact tracing remains of fundamental importance in identifying children at risk. Invest New Drugs, 2000 Aug, 18(3), 205 - 20 Development of multidrug-resistance convertors: sense or nonsense? van Zuylen L, Nooter K, Sparreboom A, Verweij J. This review describes the clinical relevance of the two drug transporters P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) and the in vitro phenomenon which is referred to as multidrug resistance (MDR) . The attempts to try to block these resistance mechanisms are summarized with specific attention for the intentionally designed "second generation" MDR-convertors . Potential explanations of the limited clinical success rate are given and recommendations for the design of future studies provided. S Afr Med J, 2000 Apr, 90(4), 381 - 6 Drug-resistant pulmonary tuberculosis in a cohort of southern African goldminers with a high prevalence of HIV infection; Murray J et al.; OBJECTIVES: To determine rates of drug resistance to Mycobacterium tuberculosis and associated risk factors, including HIV infection . DESIGN: Prospective cohort study of patients with pulmonary tuberculosis . SETTING: The study population comprised 28,522 men working on four goldmines in Westonaria, Gauteng . Health care is provided at a 240-bed mine hospital, Gold Fields West Hospital, and its primary health care facilities . SUBJECTS: All 425 patients with culture-positive pulmonary tuberculosis identified in 1995 . OUTCOME MEASURES: Tuberculosis drug resistance on enrollment and after 6 months' treatment . RESULTS: There were 292 cases of new tuberculosis, 77 of recurrent disease and 56 prevalent cases in treatment failure . Two hundred and seven patients (48.7%) were HIV infected . Primary resistance to one or more drugs (9%) was similar to the 11% found in a previous study done on goldminers in 1989 . Primary multidrug resistance (0.3%) was also similar (0.8%) . Acquired multidrug resistance was 18.1%: 6.5% for recurrent disease and 33.9% in treatment failure cases . Neither HIV infection nor the degree of immunosuppression as assessed by CD4+ lymphocyte counts was associated with drug resistance at the start or end of treatment . New patterns of drug resistance were present in 9 of 52 patients in treatment failure at 6 months, 1 of whom was HIV-infected . CONCLUSION: Primary and acquired drug resistance rates are stable in this population and are not affected by the high prevalence of HIV infection. J Org Chem, 2000 Aug 11, 65(16), 4973 - 83 The synthesis and evaluation of a solution phase indexed combinatorial library of non-natural polyenes for reversal of P-glycoprotein mediated multidrug resistance; Andrus MB et al.; A combinatorial library of polyenes, based on (-)-stipiamide, has been constructed and evaluated for the discovery of new multidrug resistance reversal agents . A palladium coupling was used to react each individual vinyl iodide with a mixture of the seven acetylenes at near 1:1 stoichiometry . The coupling was also used to react each individual acetylene with the mixture of six vinyl iodides to create 13 pools indexed in two dimensions for a total of 42 compounds . Individual compounds were detected at equimolar concentration . The vinyl iodides, made initially using a crotylborane addition to generate the anti1,2-hydroxylmethyl products, were now made using a more efficient norephedrine propionate boron enolate aldol reaction . The indexed approach, ideally suited for cellular assays that involve membrane-bound targets, allowed for the rapid identification of reversal agents using assays with drug-resistant human breast cancer MCF7-adrR cells . Intersections of potent pools identified new compounds with promising activity . Aryl dimension pools showed R = ph and naphthyl as the most potent . The acetylene dimension had R' = phenylalaninol and alaninol as the most potent . Isolated individual compounds, both active and nonpotent, were assayed to confirm the library results . The most potent new compound was 4ek (R = naphthyl, R' = phenylaninol) at 1.45 microM . Other nonnatural individual naphthyl-amide compounds showed potent MDR reversal including the morpholino-amide 4ej (1.69 microM) . Synergistic activities attributed to the two ends of the molecule were also identified . Direct interaction with Pgp was established by ATPase and photoaffinity displacement assays . The results indicate that both ends of the polyene reversal agent are involved in Pgp interaction and can be further modified for increased potency. Int J Cancer, 2000 Sep 15, 87(6), 818 - 23 Human papillomavirus type 16-immortalized endocervical cells selected for resistance to cisplatin are malignantly transformed and have a multidrug resistance phenotype; Ding Z et al.; Cis-diamminedichloroplatinum (II) (cisplatin, CDDP) is a highly effective chemotherapeutic agent against cervical cancer, but drug resistance is a major obstacle in its clinical application . The mechanism of drug resistance in human cervical cancer is not well understood . Here, we established an in vitro endocervical, cisplatin-resistant cell system that mimics the development of cisplatin resistance in the human cervix . Human papillomavirus (HPV) type 16-immortalized human endocervical cells (HEN-16-2) were treated with cisplatin, and the cisplatin-selected cells (HEN-16-2/CDDP) were resistant to cisplatin, paclitaxel, actinomycin D, doxorubicin, etoposide, and 5-fluorouracil, thus demonstrating a multidrug resistance (MDR) phenotype . Furthermore, compared with a similar passage of drug-sensitive HEN-16-2 cells, HEN-16-2/CDDP cells exhibited the general growth characteristics of cancer cell lines: faster growth in medium containing serum and high calcium levels, higher saturation density, anchorage-independent growth, and formation of tumors in nude mice . These results provided the first in vitro evidence that cisplatin selection can transform HPV-immortalized endocervical cells and cause a phenotype of MDR . Clin Cancer Res, 2000 Aug, 6(8), 3205 - 14 P-glycoprotein and multidrug resistance protein activities in relation to treatment outcome in acute myeloid leukemia; van der Kolk DM et al.; Despite treatment with intensive chemotherapy, a considerable number of patients with acute myeloid leukemia (AML) die from their disease due to the occurrence of resistance . Overexpression of the transporter proteins P-glycoprotein (P-gp) and multidrug resistance protein (MRP) 1 has been identified as a major cause of cross-resistance to functionally and structurally unrelated drugs . In the present study, the functional activity of P-gp and MRP was determined in 104 de novo AML patients with a flow cytometric assay using rhodamine 123 (Rh123) in combination with PSC833 and carboxyfluorescein (CF) in combination with MK-571 . The results were compared with clinical outcome and with known prognostic factors . The functional activity of P-gp and MRP, expressed as Rh123 efflux blocking by PSC833 and CF efflux blocking by MK-571, demonstrated a great variability in the AML patients . A strong negative correlation was observed between Rh123 efflux blocking by PSC833 and Rh123 accumulation (r(s) = -0.69, P < 0.001) and between CF efflux blocking by MK-571 and CF accumulation (r(s) = -0.59, P < 0.001) . A low Rh123 accumulation and a high Rh123 efflux blocking by PSC833 were associated with a low complete remission (CR) rate after the first cycle of chemotherapy (P = 0.008 and P = 0.01, respectively) . Patients with both low Rh123 and CF accumulation (n = 16) had the lowest CR rate (6%), whereas patients with both high Rh123 and CF accumulation (n = 11) had a CR rate of 73% . AML patients with French-American-British classification M1 or M2 showed a lower Rh123 accumulation than patients with French-American-British classification M4 or M5 (P = 0.02) . No association was observed between the multidrug resistance parameters and overall survival of the AML patients . Risk group was the only predictive parameter for overall survival (P = 0.003). Hum Gene Ther, 2000 Aug 10, 11(12), 1671 - 81 GST-pi gene-transduced hematopoietic progenitor cell transplantation overcomes the bone marrow toxicity of cyclophosphamide in mice; Matsunaga T et al.; Autologous transplantation of bone marrow cells (BMCs) transduced with the multidrug resistance 1 (MDR1) gene or dihydrofolate reductase (DHFR) gene has already been applied in clinical chemoprotection trials . However, anticancer drugs frequently used in high-dose chemotherapy (HDC), such as alkylating agents, are not relevant to MDR1 or DHFR gene products . In this context, we have previously reported that glutathione S-transferase-pi (GST-pi) gene-transduced human CD34(+) cells showed resistance in vitro against 4-hydroperoxicyclophosphamide, an active form of cyclophosphamide (CY) . In the present study, a subsequent attempt was made in a murine model to evaluate the effectiveness of transplantation of GST-pi-transduced BMCs to protect bone marrow against high-dose CY . The gene transfection was carried out retrovirally, employing a recombinant fibronectin fragment . Transfection efficiency into CFU-GM was 30% . After the transplantation, recipient mice (GST-pi mice) received three sequential courses of high-dose CY . As the chemotherapy courses advanced, both shortening of recovery period from WBC nadir and shallowing of WBC nadir were observed . In contrast to the fact that three of seven control mice died, possibly due to chemotoxicity, all seven GST-pi mice were alive after the third course, at which point the vector GST-pi gene was detected in 50% of CFU-GM derived from their BMCs and peripheral blood mononuclear cells . When BMCs obtained from these seven mice were retransplanted into secondary recipient mice, 20% of CFU-GM from BMCs showed positive signals for vector GST-pi DNA after 6 months . These data indicate that the GST-pi gene can confer resistance to bone marrow against CY by being transduced into long-term repopulating cells. Anticancer Res, 2000 Jul-Aug, 20(4), 2691 - 6 Induction of P-glycoprotein expression on the plasma membrane of human melanoma cells; Molinari A et al.; Melanoma cells exhibit, both in vivo and in vitro, intrinsic drug resistance to various chemotherapeutic agents . Cultured human melanoma cells (M14) intrinsically express significant amounts of multidrug resistance-related protein (MRP1) and P-glycoprotein (P-gp) in the Golgi apparatus, but do not express these drug transporters on the plasma membrane . A panel of multidrug resistant (MDR) melanoma cell lines (M14Dx), showing different degrees of resistance to doxorubicin (DOX), were isolated . In M14Dx lines, the appearance of surface P-gp, but not of MRP1 or lung resistance related protein (LRP), occurred in cells grown in the presence of DOX concentrations higher than 60 nM . Furthermore, P-gp levels appeared to be dose-dependent . Flow cytometry, laser scanning confocal microscopy and cytotoxicity studies demonstrated that the activity of the drug extrusion system was related to both surface P-gp expression and resistance to DOX . In conclusion, P-gp, but not MRP1 or LRP, might play a pivotal role in the pharmacologically-induced MDR phenotype of melanoma cells. Anticancer Res, 2000 Jul-Aug, 20(4), 2617 - 23 Effects of MDR reversing agent combinations on the 3H-daunomycin accumulation in drug-sensitive and drug-resistant human cancer cells; Moins N et al.; BACKGROUND: As multidrug resistant (MDR) tumour cells generally exhibit a drug accumulation deficit, the effects of three prototype modulators and their combinations were investigated by studying the modulation of 3H-dounomycin cellular accumulation . MATERIALS AND METHODS: Two cell lines derived from a rhino-pharingeal human carcinoma, either sensitive (KB-3-1) or selected as MDR (KB-A1) were used . Verapamil (10mumol.L-1), PSC 833 (lmumol.L-1) and S9788 (5mumol.L-1) were tested alone or in association two by two . The cells were characterized by reverse transcriptase polymerase chain reaction (RT-PCR) in terms of pleiotropic resistance gene expression . RESULTS: A strong mdr1 and a light LRP gene expression were found in KB-A1 resistant cells compared to KB-3-1, whereas MRP expression was found to a similar extent . Relative to the KB-3-1, cells, accumulation of 3H-daunomycin was reduced to 31 +/- 5% in the KB-A1 cells . In these KB-A1 cells, the three agents tested significantly increased the 3H-daunomycin intracellular concentration, S9788 being the most active (311 +/- 37%) and inducing a near complete reversion to the basal level of the sensitive cells . Verapamil and PSC 833 demonstrated an additive effect (252 +/- 69% compared to 188 +/- 33% and 126 +/- 27%, respectively) . On KB-3-1 sensitive cells, S9788 had no effect, while verapamil or PSC 833 moderately increased the 3H-daunomycin accumulation, without additive effect . CONCLUSION: These results show a strong MDR reversing effect of S9788, which appears specific to P-glycoprotein (Pgp) and an additive effect between verapamil and PSC 833, suggesting a better therapeutic efficiency if used in well defined combinations. Anticancer Res, 2000 Jul-Aug, 20(4), 2449 - 56 Establishment and characterization of a paclitaxel-resistant human non-small cell lung cancer cell line; Chu JJ et al.; We have established a paclitaxel-resistant mutant cell line called H460/TAX which was derived from human non-small cell lung cancer (NSCLC) H460 . A 64-fold greater resistant was shown in our assay as compared with the parental cells . High specificity of drug resistance was also observed since this mutant was not cross-resistant to several other anticancer drugs . Drug accumulation in H460/TAX was significantly less than that in H460 . Many endogenous protein profiles were intact, including the expression level of P-glycoprotein, multidrug resistance-associated protein, the 70 kDa heat shock proteins as well as the phosphorylation of Bcl-2 in H460/TAX cells, except that the total amount of alpha- and beta- tubulins was higher in H460/TAX than in H460 cells . Higher drug concentration and longer treatment for paclitaxel were required in H460/TAX to exert the phosphorylation of keratin 19 which was then accompanied by reorganization of the intermediate filament and the microtubule networks . Since all of the aforementioned factors involved in paclitaxel-resistance in other systems were not found to be significantly altered in H460/TAX, there must be other paclitaxel-resistance mechanisms(s) which remains to be identified in human lung cancers. Antimicrob Agents Chemother, 2000 Sep, 44(9), 2431 - 4 Nonylphenolethoxylates as malarial chloroquine resistance reversal agents; Crandall I et al.; Malaria-associated morbidity and mortality are increasing because of widespread resistance to one of the safest and least expensive antimalarials, chloroquine . The availability of an inexpensive agent that is capable of reversing chloroquine resistance would have a major impact on malaria treatment worldwide . The interaction of nonylphenolethoxylates (NPEs, commercially available synthetic surfactants) with drug-resistant Plasmodium falciparum was examined to determine if NPEs inhibited the growth of the parasites and if NPEs could sensitize resistant parasites to chloroquine . NPEs inhibited the development of the parasite when present in the low- to mid-micromolar range (5 to 90 microM), indicating that they possess antimalarial activity . Further, the presence of <10 microM concentrations of NPEs caused the 50% inhibitory concentrations for chloroquine-resistant lines to drop to levels (< or =12 nM) observed for sensitive lines and generally considered to be achievable with treatment courses of chloroquine . Long-chain (>30 ethoxylate units) NPEs were found to be most active in P . falciparum, which contrasts with previously observed maximal activity of short-chain ( approximately 9 ethoxylate units) NPEs in multidrug-resistant mammalian cell lines . NPEs may be attractive chloroquine resistance reversal agents since they are inexpensive and may be selectively directed against P . falciparum without inhibiting mammalian tissue P glycoproteins . Antimalarial preparations that include these agents may prolong the effective life span of chloroquine and other antimalarials. Antimicrob Agents Chemother, 2000 Sep, 44(9), 2395 - 8 Therapeutic responses to quinine and clindamycin in multidrug-resistant falciparum malaria; Pukrittayakamee S et al.; Therapeutic responses to clindamycin in combination with quinine were assessed in adult Thai patients with uncomplicated multidrug-resistant Plasmodium falciparum malaria . In total 204 patients were randomized to receive a 7-day oral treatment regimen of quinine (Q(7)) either alone (n = 68), in combination with clindamycin (Q(7)C(7); n = 68), or in combination with tetracycline (Q(7)T(7); n = 68) . All patients had uncomplicated recoveries with no serious adverse effects . Fever clearance times for both of the two combination regimens (median of 47 h and range of 8 to 120 h for Q(7)C(7) and median of 36 h and range of 8 to 117 h for Q(7)T(7)) were significantly shorter than that for the Q(7)-only regimen (median, 56; range, 4 to 152 h) (P = 0.002) . Parasite clearance times (overall mean +/- standard deviation, 78 +/- 23 h) were not significantly different between the three treatment groups (P = 0 . 98) . The cure rates assessed at 28 days of follow-up were 100% for Q(7)C(7) and 98% for Q(7)T(7), whereas the cure rate was 87% for the Q(7)-only regimen (P < or = 0.04) . Clindamycin in combination with quinine is a safe and effective treatment for multidrug-resistant P . falciparum malaria . This combination may be of particular value in children and pregnant women, in whom tetracyclines are contraindicated. Eur J Biochem, 2000 Sep, 267(17), 5369 - 77 Evaluating limited specificity of drug pumps reduced relative resistance in human MDR phenotypes; Jongsma AP et al.; In the parallel paper, we developed a property to characterize drug efflux pumps, i.e . the reduced relative resistance (RRR) . Using this RRR, we here investigate whether the observed diversity in human multidrug resistance (MDR) phenotypes might be due to variable levels of P-glycoprotein encoded by MDR1 . We analyzed resistance phenotypes of various human cell lines in which either one, or both, classical human multidrug resistance genes, MDR1 and MDR3, are overexpressed . In addition, RRR values were calculated for MDR phenotypes presented in the literature . The results suggest that more than a single mechanism is required to account for the observed phenotypic diversity of classical multidrug resistance . This diversity is only partly due to differences in plasma membrane permeabilities between cell line families . It is discussed whether the alternative MDR phenotypes might be MDR1 phenotypes modified by other factors that do not themselves cause MDR . The method we here apply may also be useful for other nonspecific enzymes or pumps. Eur J Biochem, 2000 Sep, 267(17), 5355 - 68 Relating multidrug resistance phenotypes to the kinetic properties of their drug-efflux pumps; Westerhoff HV et al.; The simplest model for pump-mediated multidrug resistance is elaborated quantitatively . The way in which toxicity data should be evaluated to characterize most effectively the drug-efflux pump is then examined . The isotoxic drug dose (D10) depends on too many unrelated properties . The D10 of a cell line taken relative to that of the parental (nonresistant) cell line has been called the relative resistance (RR) . This is inappropriate for characterizing the drug pump, as it depends on the extent of amplification of the latter . The reduced RR (RRR) is newly defined as the ratio of the (RR - 1) for one drug to the (RR - 1) for a different drug . This RRR should be independent of both the drug-target affinity and the extent of amplification of the drug pump in cell lines belonging to a family . The RRR depends on the avidities with which the pump extrudes the drugs relative to the passive membrane permeabilities of the latter . In plots of RRR for one drug combination vs . that for a second drug combination, cell lines that have the same pump amplified should cluster, whereas those with amplification of (functionally) different drug-efflux pumps should segregate . Both a set of new experimental data and literature results are discussed in terms of RRR . RRRs discriminate between human MDR1 and mouse mdr1a and mdr1b, between hamster pgp1 and a mutant thereof, as well as between human MDR1 and a mutant thereof . RRRs are not affected by changes in membrane surface area . Our results indicate that RRR may be used to (a) characterize drug-resistance mechanisms and (b) determine which drug-resistance mechanism is operative . Moreover, our analysis suggests that some of the reported phenotypic diversity among multidrug-resistant cell lines may not be due to diversity in the resistance mechanism. Eur J Biochem, 2000 Sep, 267(17), 5306 - 12 Nucleotide-binding domain 1 of cystic fibrosis transmembrane conductance regulator production of a suitable protein for structural studies; Duffieux F et al.; Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) . This protein belongs to the large ATP-binding cassette (ABC) family of transporters . Most patients with cystic fibrosis bear a mutation in the nucleotide-binding domain 1 (NBD1) of CFTR, which plays a key role in the activation of the channel function of CFTR . Determination of the three dimensional structure of NBD1 is essential to better understand its structure-function relationship, and relate it to the biological features of CFTR . In this paper, we report the first preparation of recombinant His-tagged NBD1, as a soluble, stable and isolated domain . The method avoids the use of renaturing processes or fusion constructs . ATPase activity assays show that the recombinant domain is functional . Using tryptophan intrinsic fluorescence, we point out that the local conformation, in the region of the most frequent mutation DeltaF508, could differ from that of the nucleotide-binding subunit of histidine permease, the only available ABC structure . We have undertaken three dimensional structure determination of NBD1, and the first two dimensional 15N-1H NMR spectra demonstrate that the domain is folded . The method should be applicable to the structural studies of NBD2 or of other NBDs from different ABC proteins of major biological interest, such as multidrug resistance protein 1 or multidrug resistance associated protein 1. Eur J Biochem, 2000 Sep, 267(17), 5298 - 305 Symmetry and structure in P-glycoprotein and ABC transporters what goes around comes around; Jones PM et al.; The ABC superfamily of membrane transporters is one of the largest classes of proteins across all species and one of the most intensely researched . ABC proteins are involved in the trafficking of a diverse variety of biological molecules across cell membranes, with some members implicated in medical syndromes such as cystic fibrosis and multidrug resistance to anti-cancer drugs . In the absence of X-ray crystallographic data, structural information has come from spectroscopy, electron microscopy, secondary structure prediction algorithms and residue substitution, epitope labelling and cysteine cross-linking studies . These have generally supported a model for the topology of the transmembrane domains of ABC transporters in which a single aqueous pore is formed by a toroidal ring of 12 alpha helices, deployed in two arcs of six helices each . Although this so-called 6 + 6 helix model can be arranged in either mirror or rotational symmetry configurations, experimental data supports the former . In this review, we put forward arguments against both configurations of this 6 + 6 helix model, based on what is known generally about symmetry relationships in proteins . We relate these arguments to P-glycoprotein, in particular, and discuss alternative models for the structure of ABC transporters in the light of the most recent research. J Histochem Cytochem, 2000 Sep, 48(9), 1215 - 22 CFTR, MDR1, and MRP1 immunolocalization in normal human nasal respiratory mucosa; Wioland MA et al.; CFTR (cystic fibrosis transmembrane conductance regulator), MDR1 (multidrug resistance), and MRP1 (multidrug resistance-associated protein), members of the ABC transporter superfamily, possess multiple functions, particularly Cl(-), anion, and glutathione conjugate transport and cell detoxification . They are also hypothesized to have a number of complementary functions . It is generally accepted that data obtained from nasal mucosa can be extrapolated to lower airway cell physiology . The aim of the present study was to investigate by immunohistochemistry the differential localization of CFTR, MDR1, and MRP1 in the normal mucosa of 10 human nasal turbinates . In ciliated epithelial cells, CFTR was inconstantly expressed at the apical cell surface, intense membranous labeling was observed for MDR1, and intense cytoplasmic labeling was observed for MRP1 . In the glands, a higher level of expression was observed on serous cells, at the apical surface (for CFTR), on lateral membranes (for MDR1), and with an intracytoplasmic distribution (for MRP1) . In conclusion, CFTR, MDR1 and MRP1 are expressed in the epithelium and glands of the nasal respiratory mucosa, but with different patterns of expression . These results suggest major roles for CFTR, MDR1, and MRP1 in serous glandular cells and a protective function for MDR1 and MRP1 in respiratory ciliated cells . (J Histochem Cytochem 48:1215-1222, 2000) J Chemother, 2000 Aug, 12(4), 360 - 6 A pilot study of low dose hydroxyurea as a novel resistance modulator in metastatic renal cell cancer; Hao D et al.; Mechanisms of chemoresistance in renal cell carcinoma include P-glycoprotein, overexpression of multidrug resistance-1 (mdr1) gene, and unstable chromosomal aberrations . In vitro exposure of resistant tumor cells to low dose hydroxyurea causes loss of chromosomal aberrations, decrease in the mdr1 gene copies, and increased sensitivity to vinblastine . Patients received continuous hydroxyurea 500 mg every Monday, Wednesday and Friday . Vinblastine 5 mg/m2 was given intravenously on days 1 and 8 every 21 days . Seventeen patients with a median age of 63 (range 40-80) received a median of 3 courses of vinblastine (range 1-14) . Toxicities included: > or = grade 3 non-hematologic toxicity (1) and febrile neutropenia (2) . No treatment related mortality occurred . Three patients (17.6%) had partial responses . The median survival was 38.0 weeks (95% CI = 26.9-49.1 weeks) . The addition of hydroxyurea given at the dose of 500 mg orally three times weekly had no major impact on the expected antitumor effect of vinblastine. Int J Tuberc Lung Dis, 2000 Aug, 4(8), 758 - 64 Multidrug-resistant tuberculosis: long-term treatment outcome in the Netherlands; Geerligs WA et al.; SETTING: Tuberculosis units (Beatrixoord, Haren; and Dekkerswald, Groesbeek) in the Netherlands . OBJECTIVE: To study the long-term treatment outcome of patients with multidrug-resistant tuberculosis (MDR-TB) . DESIGN: Descriptive analysis of all consecutively admitted patients with MDR-TB between 1 January 1985 and 1 September 1998, with follow-up until 1 August 1999 . RESULTS: Of 44 patients (31 male) enrolled in the study, 33 were foreign born and none were human immunodeficiency virus positive . At diagnosis 38 patients had sputum-smear positive pulmonary TB, and converted culture negative after a mean of 6 weeks, while six converted to negative later (mean 69 weeks) . Most patients had micro-organisms resistant to several antimycobacterial drugs (mean = median: 5), including resistance to isoniazid and rifampin . In-patient treatment lasted a mean of 164 days (range 31-481), and patients were treated with six drugs on average . Side effects were common . Treatment lasted for a mean of 608 days (range 268-1626); five patients are still on treatment . Four patients were operated for TB, and two others were operated for post-TB sequelae . During the follow-up period six patients died, of whom three had active TB; 33 (75%) were considered cured . CONCLUSION: Mortality was only 14% after a mean follow-up period of 53 months . MDR-TB can be successfully treated, but requires much effort from both patients and carers, and the costs may be higher than is affordable in resource-poor countries. Int J Tuberc Lung Dis, 2000 Aug, 4(8), 752 - 7 Trends in antituberculosis drug resistance in Karonga District, Malawi, 1986-1998; Warndorff DK et al.; SETTING: Karonga District, Malawi . OBJECTIVES: To examine long term trends in initial and acquired resistance to antituberculosis drugs in a rural area of Africa . DESIGN: Monitoring of all patients with culture-confirmed tuberculosis 1986-1998 . RESULTS: Initial drug resistance results were available for 1121 patients . The proportion resistant to any of the first line drugs (streptomycin, isoniazid, rifampicin or ethambutol) was 9.6%, and to isoniazid 7.2% . Initial resistance to at least isoniazid and rifampicin (multidrug resistance) was seen in only six patients . No initial resistance to ethambutol was found . There was no significant change in initial drug resistance over time . Overall, 22/120 (18%) patients with previous treatment were resistant to at least one drug; only one had multidrug resistance . Acquired resistance decreased over the period of the study . There were no associations between age, sex or human immunodeficiency virus (HIV) status and initial or acquired drug resistance . CONCLUSIONS: Changes in acquired resistance may reflect the recent performance of a control programme more quickly than those in initial resistance . It is encouraging that acquired resistance decreased and levels of multidrug resistance were low despite more than a decade of use of rifampicin . The lack of association between HIV and drug resistance confirms findings elsewhere in Africa. Int J Hyperthermia, 2000 Jul-Aug, 16(4), 291 - 303 Thermosensitivity of multidrug-resistant human gastric and pancreatic carcinoma cells; Lage H et al.; Often, tumour cells acquire drug resistance phenotypes, which include the classical multidrug resistance (MDR) phenomenon accompanied by the synthesis of the P-glycoprotein (Pgp) and atypical MDR phenotypes mediated by different, in part unknown, mechanisms . To investigate the susceptibility of tumour cells exhibiting different kinds of MDR to treatment with heat, the hyperthermic survival of established human gastric and pancreatic carcinoma cell lines were studied and sublines exhibiting a classical and an atypical MDR phenotype were derived, respectively . Arrhenius analysis of this panel of gastrointestinal tumour cells revealed that both the classical and the atypical MDR variants exhibited no breaking points (T*) in contrast to the parent tumour cells . The activation enthalpies E(A) were about 40% lower at T > T* in comparison to the E(A) at lower temperatures . Classical MDR variants of both gastrointestinal tumour cell types exhibited a similar E(A) value, whereas the E(A) of atypical MDR gastric carcinoma cells was 1.6-fold higher than the E(A) of corresponding pancreatic carcinoma cells . In comparison to the parent lines, the drug resistant variants exhibited a 2.1-fold (gastric carcinoma, classical MDR), 2.7-fold (gastric carcinoma, atypical MDR) and 1.4-fold (pancreatic carcinoma, classical MDR) increase of activation enthalpies and a nearby unchanged E(A) in pancreatic carcinoma cells exhibiting an atypical MDR. Biochem J, 2000 Sep 1, 350 Pt 2, 555 - 61 Multidrug resistance protein MRP1 protects against the toxicity of the major lipid peroxida