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Sample records for chloroquine resistance transporter

  1. Characterization of the Chloroquine Resistance Transporter Homologue in Toxoplasma gondii

    PubMed Central

    Warring, Sally D.; Dou, Zhicheng; Carruthers, Vern B.; McFadden, Geoffrey I.

    2014-01-01

    Mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein confer resistance to the antimalarial drug chloroquine. PfCRT localizes to the parasite digestive vacuole, the site of chloroquine action, where it mediates resistance by transporting chloroquine out of the digestive vacuole. PfCRT belongs to a family of transporter proteins called the chloroquine resistance transporter family. CRT family proteins are found throughout the Apicomplexa, in some protists, and in plants. Despite the importance of PfCRT in drug resistance, little is known about the evolution or native function of CRT proteins. The apicomplexan parasite Toxoplasma gondii contains one CRT family protein. We demonstrate that T. gondii CRT (TgCRT) colocalizes with markers for the vacuolar (VAC) compartment in these parasites. The TgCRT-containing VAC is a highly dynamic organelle, changing its morphology and protein composition between intracellular and extracellular forms of the parasite. Regulated knockdown of TgCRT expression resulted in modest reduction in parasite fitness and swelling of the VAC, indicating that TgCRT contributes to parasite growth and VAC physiology. Together, our findings provide new information on the role of CRT family proteins in apicomplexan parasites. PMID:24859994

  2. Multiple drugs compete for transport via the Plasmodium falciparum chloroquine resistance transporter at distinct but interdependent sites.

    PubMed

    Bellanca, Sebastiano; Summers, Robert L; Meyrath, Max; Dave, Anurag; Nash, Megan N; Dittmer, Martin; Sanchez, Cecilia P; Stein, Wilfred D; Martin, Rowena E; Lanzer, Michael

    2014-12-26

    Mutations in the "chloroquine resistance transporter" (PfCRT) are a major determinant of drug resistance in the malaria parasite Plasmodium falciparum. We have previously shown that mutant PfCRT transports the antimalarial drug chloroquine away from its target, whereas the wild-type form of PfCRT does not. However, little is understood about the transport of other drugs via PfCRT or the mechanism by which PfCRT recognizes different substrates. Here we show that mutant PfCRT also transports quinine, quinidine, and verapamil, indicating that the protein behaves as a multidrug resistance carrier. Detailed kinetic analyses revealed that chloroquine and quinine compete for transport via PfCRT in a manner that is consistent with mixed-type inhibition. Moreover, our analyses suggest that PfCRT accepts chloroquine and quinine at distinct but antagonistically interacting sites. We also found verapamil to be a partial mixed-type inhibitor of chloroquine transport via PfCRT, further supporting the idea that PfCRT possesses multiple substrate-binding sites. Our findings provide new mechanistic insights into the workings of PfCRT, which could be exploited to design potent inhibitors of this key mediator of drug resistance. PMID:25378409

  3. Plasmodium falciparum chloroquine resistance transporter is a H+-coupled polyspecific nutrient and drug exporter

    PubMed Central

    Juge, Narinobu; Moriyama, Sawako; Miyaji, Takaaki; Kawakami, Mamiyo; Iwai, Haruka; Fukui, Tomoya; Nelson, Nathan; Omote, Hiroshi; Moriyama, Yoshinori

    2015-01-01

    Extrusion of chloroquine (CQ) from digestive vacuoles through the Plasmodium falciparum CQ resistance transporter (PfCRT) is essential to establish CQ resistance of the malaria parasite. However, the physiological relevance of PfCRT and how CQ-resistant PfCRT gains the ability to transport CQ remain unknown. We prepared proteoliposomes containing purified CQ-sensitive and CQ-resistant PfCRTs and measured their transport activities. All PfCRTs tested actively took up tetraethylammonium, verapamil, CQ, basic amino acids, polypeptides, and polyamines at the expense of an electrochemical proton gradient. CQ-resistant PfCRT exhibited decreased affinity for CQ, resulting in increased CQ uptake. Furthermore, CQ competitively inhibited amino acid transport. Thus, PfCRT is a H+-coupled polyspecific nutrient and drug exporter. PMID:25733858

  4. Plasmodium falciparum chloroquine resistance transporter is a H+-coupled polyspecific nutrient and drug exporter.

    PubMed

    Juge, Narinobu; Moriyama, Sawako; Miyaji, Takaaki; Kawakami, Mamiyo; Iwai, Haruka; Fukui, Tomoya; Nelson, Nathan; Omote, Hiroshi; Moriyama, Yoshinori

    2015-03-17

    Extrusion of chloroquine (CQ) from digestive vacuoles through the Plasmodium falciparum CQ resistance transporter (PfCRT) is essential to establish CQ resistance of the malaria parasite. However, the physiological relevance of PfCRT and how CQ-resistant PfCRT gains the ability to transport CQ remain unknown. We prepared proteoliposomes containing purified CQ-sensitive and CQ-resistant PfCRTs and measured their transport activities. All PfCRTs tested actively took up tetraethylammonium, verapamil, CQ, basic amino acids, polypeptides, and polyamines at the expense of an electrochemical proton gradient. CQ-resistant PfCRT exhibited decreased affinity for CQ, resulting in increased CQ uptake. Furthermore, CQ competitively inhibited amino acid transport. Thus, PfCRT is a H(+)-coupled polyspecific nutrient and drug exporter. PMID:25733858

  5. Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, enlarge the parasite's food vacuole and alter drug sensitivities.

    PubMed

    Pulcini, Serena; Staines, Henry M; Lee, Andrew H; Shafik, Sarah H; Bouyer, Guillaume; Moore, Catherine M; Daley, Daniel A; Hoke, Matthew J; Altenhofen, Lindsey M; Painter, Heather J; Mu, Jianbing; Ferguson, David J P; Llinás, Manuel; Martin, Rowena E; Fidock, David A; Cooper, Roland A; Krishna, Sanjeev

    2015-01-01

    Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, are the major determinant of chloroquine resistance in this lethal human malaria parasite. Here, we describe P. falciparum lines subjected to selection by amantadine or blasticidin that carry PfCRT mutations (C101F or L272F), causing the development of enlarged food vacuoles. These parasites also have increased sensitivity to chloroquine and some other quinoline antimalarials, but exhibit no or minimal change in sensitivity to artemisinins, when compared with parental strains. A transgenic parasite line expressing the L272F variant of PfCRT confirmed this increased chloroquine sensitivity and enlarged food vacuole phenotype. Furthermore, the introduction of the C101F or L272F mutation into a chloroquine-resistant variant of PfCRT reduced the ability of this protein to transport chloroquine by approximately 93 and 82%, respectively, when expressed in Xenopus oocytes. These data provide, at least in part, a mechanistic explanation for the increased sensitivity of the mutant parasite lines to chloroquine. Taken together, these findings provide new insights into PfCRT function and PfCRT-mediated drug resistance, as well as the food vacuole, which is an important target of many antimalarial drugs. PMID:26420308

  6. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter.

    PubMed

    Petersen, Ines; Gabryszewski, Stanislaw J; Johnston, Geoffrey L; Dhingra, Satish K; Ecker, Andrea; Lewis, Rebecca E; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp P; Palatulan, Eugene; Johnson, David J; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M; Lanzer, Michael; Fidock, David A

    2015-07-01

    The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria. PMID:25898991

  7. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter

    PubMed Central

    Petersen, Ines; Gabryszewski, Stanislaw J.; Johnston, Geoffrey L.; Dhingra, Satish K.; Ecker, Andrea; Lewis, Rebecca E.; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp H.; Palatulan, Eugene; Johnson, David J.; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M.; Lanzer, Michael; Fidock, David A.

    2015-01-01

    Summary The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria. PMID:25898991

  8. Molecular Mechanisms for Drug Hypersensitivity Induced by the Malaria Parasite's Chloroquine Resistance Transporter.

    PubMed

    Richards, Sashika N; Nash, Megan N; Baker, Eileen S; Webster, Michael W; Lehane, Adele M; Shafik, Sarah H; Martin, Rowena E

    2016-07-01

    Mutations in the Plasmodium falciparum 'chloroquine resistance transporter' (PfCRT) confer resistance to chloroquine (CQ) and related antimalarials by enabling the protein to transport these drugs away from their targets within the parasite's digestive vacuole (DV). However, CQ resistance-conferring isoforms of PfCRT (PfCRTCQR) also render the parasite hypersensitive to a subset of structurally-diverse pharmacons. Moreover, mutations in PfCRTCQR that suppress the parasite's hypersensitivity to these molecules simultaneously reinstate its sensitivity to CQ and related drugs. We sought to understand these phenomena by characterizing the functions of PfCRTCQR isoforms that cause the parasite to become hypersensitive to the antimalarial quinine or the antiviral amantadine. We achieved this by measuring the abilities of these proteins to transport CQ, quinine, and amantadine when expressed in Xenopus oocytes and complemented this work with assays that detect the drug transport activity of PfCRT in its native environment within the parasite. Here we describe two mechanistic explanations for PfCRT-induced drug hypersensitivity. First, we show that quinine, which normally accumulates inside the DV and therewithin exerts its antimalarial effect, binds extremely tightly to the substrate-binding site of certain isoforms of PfCRTCQR. By doing so it likely blocks the normal physiological function of the protein, which is essential for the parasite's survival, and the drug thereby gains an additional killing effect. In the second scenario, we show that although amantadine also sequesters within the DV, the parasite's hypersensitivity to this drug arises from the PfCRTCQR-mediated transport of amantadine from the DV into the cytosol, where it can better access its antimalarial target. In both cases, the mutations that suppress hypersensitivity also abrogate the ability of PfCRTCQR to transport CQ, thus explaining why rescue from hypersensitivity restores the parasite

  9. Glutathione Transport: A New Role for PfCRT in Chloroquine Resistance

    PubMed Central

    Patzewitz, Eva-Maria; Salcedo-Sora, J. Enrique; Wong, Eleanor H.; Sethia, Sonal; Stocks, Paul A.; Maughan, Spencer C.; Murray, James A.H.; Krishna, Sanjeev; Bray, Patrick G.

    2013-01-01

    Abstract Aims: Chloroquine (CQ) kills Plasmodium falciparum by binding heme, preventing its detoxification to hemozoin in the digestive vacuole (DV) of the parasite. CQ resistance (CQR) is associated with mutations in the DV membrane protein P. falciparum chloroquine resistance transporter (PfCRT), mediating the leakage of CQ from the DV. However, additional factors are thought to contribute to the resistance phenotype. This study tested the hypothesis that there is a link between glutathione (GSH) and CQR. Results: Using isogenic parasite lines carrying wild-type or mutant pfcrt, we reveal lower levels of GSH in the mutant lines and enhanced sensitivity to the GSH synthesis inhibitor l-buthionine sulfoximine, without any alteration in cytosolic de novo GSH synthesis. Incubation with N-acetylcysteine resulted in increased GSH levels in all parasites, but only reduced susceptibility to CQ in PfCRT mutant-expressing lines. In support of a heme destruction mechanism involving GSH in CQR parasites, we also found lower hemozoin levels and reduced CQ binding in the CQR PfCRT-mutant lines. We further demonstrate via expression in Xenopus laevis oocytes that the mutant alleles of Pfcrt in CQR parasites selectively transport GSH. Innovation: We propose a mechanism whereby mutant pfcrt allows enhanced transport of GSH into the parasite's DV. The elevated levels of GSH in the DV reduce the level of free heme available for CQ binding, which mediates the lower susceptibility to CQ in the PfCRT mutant parasites. Conclusion: PfCRT has a dual role in CQR, facilitating both efflux of harmful CQ from the DV and influx of beneficial GSH into the DV. Antioxid. Redox Signal. 19, 683–695. PMID:23256874

  10. Molecular Mechanisms for Drug Hypersensitivity Induced by the Malaria Parasite’s Chloroquine Resistance Transporter

    PubMed Central

    Baker, Eileen S.; Webster, Michael W.; Lehane, Adele M.; Shafik, Sarah H.; Martin, Rowena E.

    2016-01-01

    Mutations in the Plasmodium falciparum ‘chloroquine resistance transporter’ (PfCRT) confer resistance to chloroquine (CQ) and related antimalarials by enabling the protein to transport these drugs away from their targets within the parasite’s digestive vacuole (DV). However, CQ resistance-conferring isoforms of PfCRT (PfCRTCQR) also render the parasite hypersensitive to a subset of structurally-diverse pharmacons. Moreover, mutations in PfCRTCQR that suppress the parasite’s hypersensitivity to these molecules simultaneously reinstate its sensitivity to CQ and related drugs. We sought to understand these phenomena by characterizing the functions of PfCRTCQR isoforms that cause the parasite to become hypersensitive to the antimalarial quinine or the antiviral amantadine. We achieved this by measuring the abilities of these proteins to transport CQ, quinine, and amantadine when expressed in Xenopus oocytes and complemented this work with assays that detect the drug transport activity of PfCRT in its native environment within the parasite. Here we describe two mechanistic explanations for PfCRT-induced drug hypersensitivity. First, we show that quinine, which normally accumulates inside the DV and therewithin exerts its antimalarial effect, binds extremely tightly to the substrate-binding site of certain isoforms of PfCRTCQR. By doing so it likely blocks the normal physiological function of the protein, which is essential for the parasite’s survival, and the drug thereby gains an additional killing effect. In the second scenario, we show that although amantadine also sequesters within the DV, the parasite’s hypersensitivity to this drug arises from the PfCRTCQR-mediated transport of amantadine from the DV into the cytosol, where it can better access its antimalarial target. In both cases, the mutations that suppress hypersensitivity also abrogate the ability of PfCRTCQR to transport CQ, thus explaining why rescue from hypersensitivity restores the parasite

  11. Full-length sequence analysis of chloroquine resistance transporter gene in Plasmodium falciparum isolates from Sabah, Malaysia.

    PubMed

    Tan, Lii Lian; Lau, Tiek Ying; Timothy, William; Prabakaran, Dhanaraj

    2014-01-01

    Chloroquine resistance (CQR) in falciparum malaria was identified to be associated with several mutations in the chloroquine resistance transporter gene (pfcrt) that encodes the transmembrane transporter in digestive vacuole membrane of the parasite. This study aimed to investigate the point mutations across the full-length pfcrt in Plasmodium falciparum isolates in Sabah, Malaysia. A total of 31 P. falciparum positive samples collected from Keningau, Kota Kinabalu, and Kudat, Sabah, were analyzed. pfcrt was PCR amplified and cloned prior to sequence analysis. This study showed that all the previously described 10 point mutations associated with CQR at codons 72, 74, 75, 76, 97, 220, 271, 326, 356, and 371 were found with different prevalence. Besides, two novel point mutations, I166V and H273N, were identified with 22.5% and 19.3%, respectively. Three haplotypes, namely, CVMNK (29%), CVIET (3.2%), and SVMNT (67.7%), were identified. High prevalence of SVMNT among P. falciparum isolates from Sabah showed that these isolates are closer to the P. falciparum isolates from Papua New Guinea rather than to the more proximal Southeast Asian CVIET haplotype. Full-length analysis of pfcrt showed that chloroquine resistant P. falciparum in Sabah is still prevalent despite the withdrawal of chloroquine usage since 1979. PMID:25574497

  12. Are transporter genes other than the chloroquine resistance locus (pfcrt) and multidrug resistance gene (pfmdr) associated with antimalarial drug resistance?

    PubMed

    Anderson, Timothy J C; Nair, Shalini; Qin, Huang; Singlam, Sittaporn; Brockman, Alan; Paiphun, Lucy; Nosten, François

    2005-06-01

    Mu et al. (Mu, J., M. T. Ferdig, X. Feng, D. A. Joy, J. Duan, T. Furuya, G. Subramanian, L. Aravind, R. A. Cooper, J. C. Wootton, M. Xiong, and X. Z. Su, Mol. Microbiol. 49:977-989, 2003) recently reported exciting associations between nine new candidate transporter genes and in vitro resistance to chloroquine (CQ) and quinine (QN), with six of these loci showing association with CQ or QN in a southeast Asian population sample. We replicated and extended this work by examining polymorphisms in these genes and in vitro resistance to eight drugs in parasites collected from the Thailand-Burma border. To minimize problems of multiple testing, we used a two-phase study design, while to minimize problems caused by population structure, we analyzed parasite isolates collected from a single clinic. We first examined associations between genotype and drug response in 108 unique single-clone parasite isolates. We found strong associations between single nucleotide polymorphisms in pfmdr and mefloquine (MFQ), artesunate (AS), and lumefantrine (LUM) response. We also observed associations between an ABC transporter (G7) and response to QN and AS and between another ABC transporter (G49) and response to dihydro-artemisinin (DHA). We reexamined significant associations in an independent sample of 199 unique single-clone infections from the same location. The significant associations with pfmdr-1042 detected in the first survey remained. However, with the exception of the G7-artesunate association, all other associations observed with the nine new candidate transporters disappeared. We also examined linkage disequilibrium (LD) between markers and phenotypic correlations between drug responses. We found minimal LD between genes. Furthermore, we found no correlation between chloroquine and quinine responses, although we did find expected strong correlations between MFQ, QN, AS, DHA, and LUM. To conclude, we found no evidence for an association between 8/9 candidate genes and

  13. Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, enlarge the parasite’s food vacuole and alter drug sensitivities

    PubMed Central

    Pulcini, Serena; Staines, Henry M.; Lee, Andrew H.; Shafik, Sarah H.; Bouyer, Guillaume; Moore, Catherine M.; Daley, Daniel A.; Hoke, Matthew J.; Altenhofen, Lindsey M.; Painter, Heather J.; Mu, Jianbing; Ferguson, David J. P.; Llinás, Manuel; Martin, Rowena E.; Fidock, David A.; Cooper, Roland A.; Krishna, Sanjeev

    2015-01-01

    Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, are the major determinant of chloroquine resistance in this lethal human malaria parasite. Here, we describe P. falciparum lines subjected to selection by amantadine or blasticidin that carry PfCRT mutations (C101F or L272F), causing the development of enlarged food vacuoles. These parasites also have increased sensitivity to chloroquine and some other quinoline antimalarials, but exhibit no or minimal change in sensitivity to artemisinins, when compared with parental strains. A transgenic parasite line expressing the L272F variant of PfCRT confirmed this increased chloroquine sensitivity and enlarged food vacuole phenotype. Furthermore, the introduction of the C101F or L272F mutation into a chloroquine-resistant variant of PfCRT reduced the ability of this protein to transport chloroquine by approximately 93 and 82%, respectively, when expressed in Xenopus oocytes. These data provide, at least in part, a mechanistic explanation for the increased sensitivity of the mutant parasite lines to chloroquine. Taken together, these findings provide new insights into PfCRT function and PfCRT-mediated drug resistance, as well as the food vacuole, which is an important target of many antimalarial drugs. PMID:26420308

  14. Molecular interaction of selected phytochemicals under the charged environment of Plasmodium falciparum chloroquine resistance transporter (PfCRT) model.

    PubMed

    Patel, Saumya K; Khedkar, Vijay M; Jha, Prakash C; Jasrai, Yogesh T; Pandya, Himanshu A; George, Linz-Buoy; Highland, Hyacinth N; Skelton, Adam A

    2016-01-01

    Phytochemicals of Catharanthus roseus Linn. and Tylophora indica have been known for their inhibition of malarial parasite, Plasmodium falciparum in cell culture. Resistance to chloroquine (CQ), a widely used antimalarial drug, is due to the CQ resistance transporter (CRT) system. The present study deals with computational modeling of Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein and development of charged environment to mimic a condition of resistance. The model of PfCRT was developed using Protein homology/analogy engine (PHYRE ver 0.2) and was validated based on the results obtained using PSI-PRED. Subsequently, molecular interactions of selected phytochemicals extracted from C. roseus Linn. and T. indica were studied using multiple-iterated genetic algorithm-based docking protocol in order to investigate the translocation of these legends across the PfCRT protein. Further, molecular dynamics studies exhibiting interaction energy estimates of these compounds within the active site of the protein showed that compounds are more selective toward PfCRT. Clusters of conformations with the free energy of binding were estimated which clearly demonstrated the potential channel and by this means the translocation across the PfCRT is anticipated. PMID:25783783

  15. Dynamic of plasmodium falciparum chloroquine resistance transporter gene Pfcrt K76T mutation five years after withdrawal of chloroquine in Burkina Faso

    PubMed Central

    Sondo, Paul; Derra, Karim; Tarnagda, Zekiba; Nakanabo, Seydou Diallo; Zampa, Odile; Kazienga, Adama; Valea, Innocent; Sorgho, Hermann; Ouedraogo, Jean-Bosco; Guiguemde, Tinga Robert; Tinto, Halidou

    2015-01-01

    We investigated the evolution of Pfcrt K76T mutation five years after the withdrawal of chloroquine in Burkina Faso. A total of 675 clinical isolates collected from October 2010 to September 2012 were successfully genotyped. Single nucleotide polymorphism in Pfcrt (codon 76) gene was analyzed. The prevalence of resistant Pfcrt 76T allele was 20.55%. There was a progressive decrease of the proportion of mutant type pfcrt T76 from 2010 to 2012 (X2=5.508 p=0.0189). Our results suggest a progressive return of the wild type Pfcrt K76 in Burkina Faso but the prevalence of the mutants Pfcrt T76 still remains high. PMID:26516402

  16. Dynamic of plasmodium falciparum chloroquine resistance transporter gene Pfcrt K76T mutation five years after withdrawal of chloroquine in Burkina Faso.

    PubMed

    Sondo, Paul; Derra, Karim; Tarnagda, Zekiba; Nakanabo, Seydou Diallo; Zampa, Odile; Kazienga, Adama; Valea, Innocent; Sorgho, Hermann; Ouedraogo, Jean-Bosco; Guiguemde, Tinga Robert; Tinto, Halidou

    2015-01-01

    We investigated the evolution of Pfcrt K76T mutation five years after the withdrawal of chloroquine in Burkina Faso. A total of 675 clinical isolates collected from October 2010 to September 2012 were successfully genotyped. Single nucleotide polymorphism in Pfcrt (codon 76) gene was analyzed. The prevalence of resistant Pfcrt 76T allele was 20.55%. There was a progressive decrease of the proportion of mutant type pfcrt T76 from 2010 to 2012 (X2=5.508 p=0.0189). Our results suggest a progressive return of the wild type Pfcrt K76 in Burkina Faso but the prevalence of the mutants Pfcrt T76 still remains high. PMID:26516402

  17. Metabolic QTL Analysis Links Chloroquine Resistance in Plasmodium falciparum to Impaired Hemoglobin Catabolism

    PubMed Central

    Olszewski, Kellen L.; Cobbold, Simon A.; Baska, Katelynn S.; Tan, Asako; Ferdig, Michael T.; Llinás, Manuel

    2014-01-01

    Drug resistant strains of the malaria parasite, Plasmodium falciparum, have rendered chloroquine ineffective throughout much of the world. In parts of Africa and Asia, the coordinated shift from chloroquine to other drugs has resulted in the near disappearance of chloroquine-resistant (CQR) parasites from the population. Currently, there is no molecular explanation for this phenomenon. Herein, we employ metabolic quantitative trait locus mapping (mQTL) to analyze progeny from a genetic cross between chloroquine-susceptible (CQS) and CQR parasites. We identify a family of hemoglobin-derived peptides that are elevated in CQR parasites and show that peptide accumulation, drug resistance, and reduced parasite fitness are all linked in vitro to CQR alleles of the P. falciparum chloroquine resistance transporter (pfcrt). These findings suggest that CQR parasites are less fit because mutations in pfcrt interfere with hemoglobin digestion by the parasite. Moreover, our findings may provide a molecular explanation for the reemergence of CQS parasites in wild populations. PMID:24391526

  18. Chloroquine-Resistant Haplotype Plasmodium falciparum Parasites, Haiti

    PubMed Central

    Londono, Berlin L.; Eisele, Thomas P.; Keating, Joseph; Bennett, Adam; Chattopadhyay, Chandon; Heyliger, Gaetan; Mack, Brian; Rawson, Ian; Vely, Jean-Francois; Désinor, Olbeg

    2009-01-01

    Plasmodium falciparum parasites have been endemic to Haiti for >40 years without evidence of chloroquine (CQ) resistance. In 2006 and 2007, we obtained blood smears for rapid diagnostic tests (RDTs) and filter paper blots of blood from 821 persons by passive and active case detection. P. falciparum infections diagnosed for 79 persons by blood smear or RDT were confirmed by PCR for the small subunit rRNA gene of P. falciparum. Amplification of the P. falciparum CQ resistance transporter (pfcrt) gene yielded 10 samples with amplicons resistant to cleavage by ApoI. A total of 5 of 9 samples had threonine at position 76 of pfcrt, which is consistent with CQ resistance (haplotypes at positions 72–76 were CVIET [n = 4] and CVMNT [n = 1]); 4 had only the wild-type haplotype associated with CQ susceptibility (CVMNK). These results indicate that CQ-resistant haplotype P. falciparum malaria parasites are present in Haiti. PMID:19402959

  19. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Singh, Raksha; Urhehar, Anant Dattatraya

    2016-01-01

    Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with

  20. Polymorphisms in Plasmodium falciparum Chloroquine Resistance Transporter and Multidrug Resistance 1 Genes: Parasite Risk Factors that Affect Treatment Outcomes for P. falciparum Malaria after Artemether-Lumefantrine and Artesunate-Amodiaquine

    PubMed Central

    Venkatesan, Meera; Gadalla, Nahla B.; Stepniewska, Kasia; Dahal, Prabin; Nsanzabana, Christian; Moriera, Clarissa; Price, Ric N.; Mårtensson, Andreas; Rosenthal, Philip J.; Dorsey, Grant; Sutherland, Colin J.; Guérin, Philippe; Davis, Timothy M. E.; Ménard, Didier; Adam, Ishag; Ademowo, George; Arze, Cesar; Baliraine, Frederick N.; Berens-Riha, Nicole; Björkman, Anders; Borrmann, Steffen; Checchi, Francesco; Desai, Meghna; Dhorda, Mehul; Djimdé, Abdoulaye A.; El-Sayed, Badria B.; Eshetu, Teferi; Eyase, Frederick; Falade, Catherine; Faucher, Jean-François; Fröberg, Gabrielle; Grivoyannis, Anastasia; Hamour, Sally; Houzé, Sandrine; Johnson, Jacob; Kamugisha, Erasmus; Kariuki, Simon; Kiechel, Jean-René; Kironde, Fred; Kofoed, Poul-Erik; LeBras, Jacques; Malmberg, Maja; Mwai, Leah; Ngasala, Billy; Nosten, Francois; Nsobya, Samuel L.; Nzila, Alexis; Oguike, Mary; Otienoburu, Sabina Dahlström; Ogutu, Bernhards; Ouédraogo, Jean-Bosco; Piola, Patrice; Rombo, Lars; Schramm, Birgit; Somé, A. Fabrice; Thwing, Julie; Ursing, Johan; Wong, Rina P. M.; Zeynudin, Ahmed; Zongo, Issaka; Plowe, Christopher V.; Sibley, Carol Hopkins

    2014-01-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 – 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36–17.97, P < 0.001) were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine. PMID:25048375

  1. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.

    PubMed

    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia; Dahal, Prabin; Nsanzabana, Christian; Moriera, Clarissa; Price, Ric N; Mårtensson, Andreas; Rosenthal, Philip J; Dorsey, Grant; Sutherland, Colin J; Guérin, Philippe; Davis, Timothy M E; Ménard, Didier; Adam, Ishag; Ademowo, George; Arze, Cesar; Baliraine, Frederick N; Berens-Riha, Nicole; Björkman, Anders; Borrmann, Steffen; Checchi, Francesco; Desai, Meghna; Dhorda, Mehul; Djimdé, Abdoulaye A; El-Sayed, Badria B; Eshetu, Teferi; Eyase, Frederick; Falade, Catherine; Faucher, Jean-François; Fröberg, Gabrielle; Grivoyannis, Anastasia; Hamour, Sally; Houzé, Sandrine; Johnson, Jacob; Kamugisha, Erasmus; Kariuki, Simon; Kiechel, Jean-René; Kironde, Fred; Kofoed, Poul-Erik; LeBras, Jacques; Malmberg, Maja; Mwai, Leah; Ngasala, Billy; Nosten, Francois; Nsobya, Samuel L; Nzila, Alexis; Oguike, Mary; Otienoburu, Sabina Dahlström; Ogutu, Bernhards; Ouédraogo, Jean-Bosco; Piola, Patrice; Rombo, Lars; Schramm, Birgit; Somé, A Fabrice; Thwing, Julie; Ursing, Johan; Wong, Rina P M; Zeynudin, Ahmed; Zongo, Issaka; Plowe, Christopher V; Sibley, Carol Hopkins

    2014-10-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine. PMID:25048375

  2. Chloroquine resistance of Plasmodium falciparum is associated with severity of disease in Nigerian children.

    PubMed

    Olumese, P E; Amodu, O K; Björkman, A; Adeyemo, A A; Gbadegesin, R A; Walker, O

    2002-01-01

    Chloroquine resistance of Plasmodium falciparum in vitro was significantly higher in isolates from patients with severe malaria than those with uncomplicated disease. This association may be due to either progression of uncomplicated to severe disease following chloroquine failure or increased virulence of chloroquine-resistant parasites. The implication of this for antimalarial treatment policy is discussed. PMID:12497979

  3. Activities of Various 4-Aminoquinolines Against Infections with Chloroquine-Resistant Strains of Plasmodium falciparum1

    PubMed Central

    Schmidt, L. H.; Vaughan, Dennis; Mueller, Donna; Crosby, Ruth; Hamilton, Rebecca

    1977-01-01

    The studies reported here stemmed from a personal report by Geiman on the capacity of the 4-aminoquinoline amodiaquin to inhibit in vitro maturation of ring stages of the chloroquine-resistant Monterey strain of Plasmodium falciparum. This observation, confirmed in owl monkeys infected with this strain, led to a comparison of the activities of chloroquine, amodiaquin, amopyroquin, and dichlorquinazine (12,278 RP) against infections with various chloroquine-susceptible and chloroquine-resistant strains. The results showed that: (i) these 4-aminoquinolines were essentially equally active against infections with chloroquine-susceptible strains and (ii) the activities of amodiaquin, amopyroquin, and dichlorquinazine were reduced significantly in the face of chloroquine resistance, but (iii) well-tolerated doses of these compounds would cure infections with strains that fully resisted treatment with maximally tolerated doses of chloroquine. Two other 4-aminoquinolines, SN-8137 and SN-9584, which also exhibited activity against chloroquine-resistant parasites in vitro, displayed curative activity in monkeys infected with a chloroquine-resistant strain. These observations show that there is cross-resistance among the 4-aminoquinolines, confirming earlier findings, but indicate that the dimensions of this phenomenon are sufficiently limited so that some derivatives are therapeutically effective against infections refractory to maximally tolerated doses of chloroquine. PMID:406829

  4. Confirmed Plasmodium vivax Resistance to Chloroquine in Central Vietnam

    PubMed Central

    Hong, Nguyen Van; Van, Nguyen Van; Louisa, Melva; Baird, Kevin; Xa, Nguyen Xuan; Peeters Grietens, Koen; Hung, Le Xuan; Duong, Tran Thanh; Rosanas-Urgell, Anna; Speybroeck, Niko; D'Alessandro, Umberto; Erhart, Annette

    2015-01-01

    Plasmodium vivax resistance to chloroquine (CQ) is currently reported in almost all countries where P. vivax is endemic. In Vietnam, despite a first report on P. vivax resistance to chloroquine published in the early 2000s, P. vivax was still considered sensitive to CQ. Between May 2009 and December 2011, a 2-year cohort study was conducted in central Vietnam to assess the recommended radical cure regimen based on a 10-day course of primaquine (0.5 mg/kg/day) together with 3 days of CQ (25 mg/kg). Here we report the results of the first 28-day follow-up estimating the cumulative risk of P. vivax recurrences together with the corresponding CQ blood concentrations, among other endpoints. Out of 260 recruited P. vivax patients, 240 completed treatment and were followed up to day 28 according to the WHO guidelines. Eight patients (3.45%) had a recurrent P. vivax infection, at day 14 (n = 2), day 21 (n = 1), and day 28 (n = 5). Chloroquine blood concentrations, available for 3/8 recurrent infections (days 14, 21, and 28), were above the MIC (>100 ng/ml whole blood) in all of these cases. Fever and parasitemia (both sexual and asexual stages) were cleared by day 3. Anemia was common at day 0 (35.8%), especially in children under 10 years (50%), and hemoglobin (Hb) recovery at day 28 was substantial among anemic patients (median change from day 0 to 28, +1.7 g/dl; interquartile range [IQR], +0.7 to +3.2). This report, based on CQ blood levels measured at the time of recurrences, confirms for the first time P. vivax CQ resistance in central Vietnam and calls for further studies using standardized protocols for accurately monitoring the extent and evolution of P. vivax resistance to chloroquine in Vietnam. These results, together with the mounting evidence of artemisinin resistance in central Vietnam, further highlight the increasing threat of antimalarial drug resistance to malaria elimination in Vietnam. PMID:26392501

  5. Chloroquine-resistant Plasmodium vivax malaria in Debre Zeit, Ethiopia

    PubMed Central

    Teka, Hiwot; Petros, Beyene; Yamuah, Lawrence; Tesfaye, Gezahegn; Elhassan, Ibrahim; Muchohi, Simon; Kokwaro, Gilbert; Aseffa, Abraham; Engers, Howard

    2008-01-01

    Background Plasmodium vivax accounts for about 40% of all malaria infection in Ethiopia. Chloroquine (CQ) is the first line treatment for confirmed P. vivax malaria in the country. The first report of CQ treatment failure in P. vivax was from Debre Zeit, which suggested the presence of chloroquine resistance. Methods An in vivo drug efficacy study was conducted in Debre Zeit from June to August 2006. Eighty-seven patients with microscopically confirmed P. vivax malaria, aged between 8 months and 52 years, were recruited and treated under supervision with CQ (25 mg/kg over three days). Clinical and parasitological parameters were assessed during the 28 day follow-up period. CQ and desethylchloroquine (DCQ) blood and serum concentrations were determined with high performance liquid chromatography (HPLC) in patients who showed recurrent parasitaemia. Results Of the 87 patients recruited in the study, one was lost to follow-up and three were excluded due to P. falciparum infection during follow-up. A total of 83 (95%) of the study participants completed the follow-up. On enrolment, 39.8% had documented fever and 60.2% had a history of fever. The geometric mean parasite density of the patients was 7045 parasites/μl. Among these, four patients had recurrent parasitaemia on Day 28. The blood CQ plus DCQ concentrations of these four patients were all above the minimal effective concentration (> 100 ng/ml). Conclusion Chloroquine-resistant P. vivax parasites are emerging in Debre Zeit, Ethiopia. A multi-centre national survey is needed to better understand the extent of P. vivax resistance to CQ in Ethiopia. PMID:18959774

  6. Synergistic Activity of Chloroquine with Fluconazole against Fluconazole-Resistant Isolates of Candida Species

    PubMed Central

    Li, Yali; Wan, Zhe; Li, Ruoyu

    2014-01-01

    The in vitro activity of chloroquine and the interactions of chloroquine combined with fluconazole against 37 Candida isolates were tested using the broth microdilution, disk diffusion, and Etest susceptibility tests. Synergistic effect was detected with 6 of 9 fluconazole-resistant Candida albicans isolates, with Candida krusei ATCC 6258, and with all 12 fluconazole-resistant Candida tropicalis isolates. PMID:25512426

  7. Overcoming chloroquine resistance in malaria: Design, synthesis and structure-activity relationships of novel chemoreversal agents.

    PubMed

    Boudhar, Aicha; Ng, Xiao Wei; Loh, Chiew Yee; Chia, Wan Ni; Tan, Zhi Ming; Nosten, Francois; Dymock, Brian W; Tan, Kevin S W

    2016-08-25

    Malaria remains a significant infectious disease with even artemisinin-based therapies now facing resistance in the field. Development of new therapies is urgently needed, either by finding new compounds with unique modes of action, or by reversing resistance towards known drugs with 'chemosensitizers' or 'chemoreversal' agents (CRA). Concerning the latter, we have focused on the resistance mechanisms developed against chloroquine (CQ). We have synthesized a series of compounds related to previously identified CRAs, and found promising novel compounds. These compounds show encouraging results in a coumarin labeled chloroquine uptake assay, exhibiting a dose response in resensitising parasites to the antimalarial effects of chloroquine. Selected compounds show consistent potency across a panel of chloroquine and artemisinin sensitive and resistant parasites, and a wide therapeutic window. This data supports further study of CRAs in the treatment of malaria and, ultimately, their use in chloroquine-based combination therapies. PMID:27173385

  8. Chloroquine-resistant malaria in travelers returning from Haiti after 2010 earthquake.

    PubMed

    Gharbi, Myriam; Pillai, Dylan R; Lau, Rachel; Hubert, Véronique; Khairnar, Krishna; Existe, Alexandre; Kendjo, Eric; Dahlström, Sabina; Guérin, Philippe J; Le Bras, Jacques

    2012-08-01

    We investigated chloroquine sensitivity to Plasmodium falciparum in travelers returning to France and Canada from Haiti during a 23-year period. Two of 19 isolates obtained after the 2010 earthquake showed mixed pfcrt 76K+T genotype and high 50% inhibitory concentration. Physicians treating malaria acquired in Haiti should be aware of possible chloroquine resistance. PMID:22840888

  9. Chloroquine-Resistant Malaria in Travelers Returning from Haiti after 2010 Earthquake

    PubMed Central

    Pillai, Dylan R.; Lau, Rachel; Hubert, Véronique; Khairnar, Krishna; Existe, Alexandre; Kendjo, Eric; Dahlström, Sabina; Guérin, Philippe J.; Le Bras, Jacques

    2012-01-01

    We investigated chloroquine sensitivity to Plasmodium falciparum in travelers returning to France and Canada from Haiti during a 23-year period. Two of 19 isolates obtained after the 2010 earthquake showed mixed pfcrt 76K+T genotype and high 50% inhibitory concentration. Physicians treating malaria acquired in Haiti should be aware of possible chloroquine resistance. PMID:22840888

  10. Polycyclic amines as chloroquine resistance modulating agents in Plasmodium falciparum.

    PubMed

    Joubert, Jacques; Kapp, Erika; Taylor, Dale; Smith, Peter J; Malan, Sarel F

    2016-02-15

    Pentacycloundecylamines (PCUs) and adamantane amines, such as NGP1-01 (1) and amantadine, have shown significant channel blocking activities. They are postulated to act as chemosensitizers and circumvent the resistance of the plasmodia parasite against chloroquine (CQ) by inhibiting the p-glycoprotein efflux pump and enabling the accumulation of CQ inside the parasite digestive vacuole. Twelve polycyclic amines containing either a PCU or adamantane amine moiety conjugated to different aromatic functionalities through various tethered linkers were selected based on their channel blocking abilities and evaluated as potential chemosensitizers. Compounds 2, 4, 5 and 10 showed significant voltage-gated calcium channel (VGCC) blocking ability (IC50=0.27-35 μM) and were able to alter the CQ IC50 in differing degrees (45-81%) in the multidrug resistant Plasmodium falciparum Dd2 isolate. Among them, the PCU-dansyl amine compound (4) displayed the best potential to act as a chemosensitizer against the Dd2 strain at a 1 μM concentration (RMI=0.19) while displaying moderate antiplasmodial activity (Dd2 IC50=6.25 μM) and low in vitro cytotoxicity against a mammalian cell line (CHO, IC50=119 μM). Compounds 2 and 10 also showed some promising chemosensitizing abilities (RMI=0.36 and 0.35 respectively). A direct correlation was found between the VGCC blocking ability of these polycyclic amines and their capacity to act as CQ resistance modulating agents. PMID:26832222

  11. Chlorpheniramine Analogues Reverse Chloroquine Resistance in Plasmodium falciparum by Inhibiting PfCRT

    PubMed Central

    2014-01-01

    The emergence and spread of malaria parasites that are resistant to chloroquine (CQ) has been a disaster for world health. The antihistamine chlorpheniramine (CP) partially resensitizes CQ-resistant (CQR) parasites to CQ but possesses little intrinsic antiplasmodial activity. Mutations in the parasite’s CQ resistance transporter (PfCRT) confer resistance to CQ by enabling the protein to transport the drug away from its site of action, and it is thought that resistance-reversers such as CP exert their effect by blocking this CQ transport activity. Here, a series of new structural analogues and homologues of CP have been synthesized. We show that these compounds (along with other in vitro CQ resistance-reversers) inhibit the transport of CQ via a resistance-conferring form of PfCRT expressed in Xenopus laevis oocytes. Furthermore, the level of PfCRT-inhibition was found to correlate well with both the restoration of CQ accumulation and the level of CQ resensitization in CQR parasites. PMID:24900883

  12. Overcoming Chloroquine Resistance in Malaria: Design, Synthesis, and Structure-Activity Relationships of Novel Hybrid Compounds.

    PubMed

    Boudhar, Aicha; Ng, Xiao Wei; Loh, Chiew Yee; Chia, Wan Ni; Tan, Zhi Ming; Nosten, Francois; Dymock, Brian W; Tan, Kevin S W

    2016-05-01

    Resistance to antimalarial therapies, including artemisinin, has emerged as a significant challenge. Reversal of acquired resistance can be achieved using agents that resensitize resistant parasites to a previously efficacious therapy. Building on our initial work describing novel chemoreversal agents (CRAs) that resensitize resistant parasites to chloroquine (CQ), we herein report new hybrid single agents as an innovative strategy in the battle against resistant malaria. Synthetically linking a CRA scaffold to chloroquine produces hybrid compounds with restored potency toward a range of resistant malaria parasites. A preferred compound, compound 35, showed broad activity and good potency against seven strains resistant to chloroquine and artemisinin. Assessment of aqueous solubility, membrane permeability, and in vitro toxicity in a hepatocyte line and a cardiomyocyte line indicates that compound 35 has a good therapeutic window and favorable drug-like properties. This study provides initial support for CQ-CRA hybrid compounds as a potential treatment for resistant malaria. PMID:26953199

  13. Genetics of chloroquine-resistant malaria: a haplotypic view

    PubMed Central

    Awasthi, Gauri; Das, Aparup

    2013-01-01

    The development and rapid spread of chloroquine resistance (CQR) in Plasmodium falciparum have triggered the identification of several genetic target(s) in the P. falciparum genome. In particular, mutations in the Pfcrt gene, specifically, K76T and mutations in three other amino acids in the region adjoining K76 (residues 72, 74, 75 and 76), are considered to be highly related to CQR. These various mutations form several different haplotypes and Pfcrt gene polymorphisms and the global distribution of the different CQR- Pfcrt haplotypes in endemic and non-endemic regions of P. falciparum malaria have been the subject of extensive study. Despite the fact that the Pfcrt gene is considered to be the primary CQR gene in P. falciparum , several studies have suggested that this may not be the case. Furthermore, there is a poor correlation between the evolutionary implications of the Pfcrt haplotypes and the inferred migration of CQR P. falciparum based on CQR epidemiological surveillance data. The present paper aims to clarify the existing knowledge on the genetic basis of the different CQR- Pfcrt haplotypes that are prevalent in worldwide populations based on the published literature and to analyse the data to generate hypotheses on the genetics and evolution of CQR malaria. PMID:24402147

  14. Bisbenzylisoquinolines as modulators of chloroquine resistance in Plasmodium falciparum and multidrug resistance in tumor cells.

    PubMed

    Frappier, F; Jossang, A; Soudon, J; Calvo, F; Rasoanaivo, P; Ratsimamanga-Urverg, S; Saez, J; Schrevel, J; Grellier, P

    1996-06-01

    Ten naturally occurring bisbenzylisoquinolines (BBIQ) and two dihydro derivatives belonging to five BBIQ subgroups were evaluated in vitro for their ability to inhibit Plasmodium falciparum growth and, in drug combination, to reverse the resistance to chloroquine of strain FcB1. The same alkaloids were also assessed in vitro for their potentiating activity against vinblastine with the multidrug-resistant clone CCRF-CEM/VLB, established from lymphoblastic acute leukemia. Three of the BBIQ tested had 50% inhibitory concentrations of less than 1 microM. The most potent antimalarial agent was cocsoline (50% inhibitory concentration, 0.22 microM). Regarding the chloroquine-potentiating effect, fangchinoline exhibited the highest biological activity whereas the remaining compounds displayed either antagonistic or slight synergistic effects. Against the multidrug-resistant cancer cell line, fangchinoline was also by far the most active compound. Although there were clear differences between the activities of tested alkaloids, no relevant structure-activity relationship could be established. Nevertheless, fangchinoline appears to be a new biochemical tool able to help in the comprehension of the mechanism of both chloroquine resistance in P. falciparum and multidrug resistance in tumor cells. PMID:8726022

  15. Bisbenzylisoquinolines as modulators of chloroquine resistance in Plasmodium falciparum and multidrug resistance in tumor cells.

    PubMed Central

    Frappier, F; Jossang, A; Soudon, J; Calvo, F; Rasoanaivo, P; Ratsimamanga-Urverg, S; Saez, J; Schrevel, J; Grellier, P

    1996-01-01

    Ten naturally occurring bisbenzylisoquinolines (BBIQ) and two dihydro derivatives belonging to five BBIQ subgroups were evaluated in vitro for their ability to inhibit Plasmodium falciparum growth and, in drug combination, to reverse the resistance to chloroquine of strain FcB1. The same alkaloids were also assessed in vitro for their potentiating activity against vinblastine with the multidrug-resistant clone CCRF-CEM/VLB, established from lymphoblastic acute leukemia. Three of the BBIQ tested had 50% inhibitory concentrations of less than 1 microM. The most potent antimalarial agent was cocsoline (50% inhibitory concentration, 0.22 microM). Regarding the chloroquine-potentiating effect, fangchinoline exhibited the highest biological activity whereas the remaining compounds displayed either antagonistic or slight synergistic effects. Against the multidrug-resistant cancer cell line, fangchinoline was also by far the most active compound. Although there were clear differences between the activities of tested alkaloids, no relevant structure-activity relationship could be established. Nevertheless, fangchinoline appears to be a new biochemical tool able to help in the comprehension of the mechanism of both chloroquine resistance in P. falciparum and multidrug resistance in tumor cells. PMID:8726022

  16. Menhaden-fish oil in a vitamin E-deficient diet: protection against chloroquine-resistant malaria in mice.

    PubMed

    Levander, O A; Ager, A L; Morris, V C; May, R G

    1989-12-01

    Feeding a vitamin E-deficient diet containing 5% menhaden oil to mice affords significant protection against both a chloroquine-sensitive and a chloroquine-resistant line of the malarial parasite. Nutritional manipulation may offer a new approach to the problem of drug-resistant malaria, a rapidly emerging global threat to public health. PMID:2688393

  17. 3-Iodo-4-aminoquinoline derivative sensitises resistant strains of Plasmodium falciparum to chloroquine.

    PubMed

    Edaye, Sonia; Tazoo, Dagobert; Bohle, D Scott; Georges, Elias

    2016-06-01

    Chloroquine (CQ), the first cost-effective synthetic antimalarial, is rendered ineffective in malaria-endemic regions owing to the rise and spread of CQ-resistant Plasmodium falciparum. In this report, we show that a halogen derivative of CQ, namely 3-iodo-CQ, inhibits the proliferation of CQ-sensitive and -resistant P. falciparum in a verapamil-insensitive manner. Similar to CQ, the antimalarial activity of 3-iodo-CQ is likely due to its inhibition of β-haematin formation. Interestingly, the presence of non-inhibitory concentrations of 3-iodo-CQ potentiated the antiproliferative activity of CQ against CQ-resistant strains or P. falciparum transfectants expressing wild-type or mutant P. falciparum CQ resistance transporter (PfCRT) (C2(GC03) or C4(Dd2), respectively). These findings demonstrate that halogenation of the third position of 4-aminoquinoline, with a simple one-step reaction from CQ, generates a novel derivative that is active against CQ-sensitive and -resistant P. falciparum, possibly by inhibiting the activity of mutant PfCRT. PMID:27211211

  18. Molecular Analysis of Chloroquine and Sulfadoxine-Pyrimethamine Resistance-Associated Alleles in Plasmodium falciparum Isolates from Nicaragua

    PubMed Central

    Sridaran, Sankar; Rodriguez, Betzabe; Mercedes Soto, Aida; Macedo De Oliveira, Alexandre; Udhayakumar, Venkatachalam

    2014-01-01

    Chloroquine (CQ) is used as a first-line therapy for the treatment of Plasmodium falciparum malaria in Nicaragua. We investigated the prevalence of molecular markers associated with CQ and sulfadoxine-pyrimethamine (SP) resistance in P. falciparum isolates obtained from the North Atlantic Autonomous Region of Nicaragua. Blood spots for this study were made available from a CQ and SP drug efficacy trial conducted in 2005 and also from a surveillance study performed in 2011. Polymorphisms in P. falciparum CQ resistance transporter, dihydrofolate reductase, and dihydropteroate synthase gene loci that are associated with resistance to CQ, pyrimethamine, and sulfadoxine, respectively, were detected by DNA sequencing. In the 2005 dataset, only 2 of 53 isolates had a CQ resistance allele (CVIET), 2 of 52 had a pyrimethamine resistance allele, and 1 of 49 had a sulfadoxine resistance allele. In the 2011 dataset, none of 45 isolates analyzed had CQ or SP resistance alleles. PMID:24615126

  19. Synthesis of New 4-Aminoquinolines and Evaluation of Their In Vitro Activity against Chloroquine-Sensitive and Chloroquine-Resistant Plasmodium falciparum

    PubMed Central

    Rajapakse, Chandima S. K.; Lisai, Maryna; Deregnaucourt, Christiane; Sinou, Véronique; Latour, Christine; Roy, Dipankar; Schrével, Joseph; Sánchez-Delgado, Roberto A.

    2015-01-01

    The efficacy of chloroquine, once the drug of choice in the fight against Plasmodium falciparum, is now severely limited due to widespread resistance. Amodiaquine is one of the most potent antimalarial 4-aminoquinolines known and remains effective against chloroquine-resistant parasites, but toxicity issues linked to a quinone-imine metabolite limit its clinical use. In search of new compounds able to retain the antimalarial activity of amodiaquine while circumventing quinone-imine metabolite toxicity, we have synthesized five 4-aminoquinolines that feature rings lacking hydroxyl groups in the side chain of the molecules and are thus incapable of generating toxic quinone-imines. The new compounds displayed high in vitro potency (low nanomolar IC50), markedly superior to chloroquine and comparable to amodiaquine, against chloroquine-sensitive and chloroquine-resistant strains of P. falciparum, accompanied by low toxicity to L6 rat fibroblasts and MRC5 human lung cells, and metabolic stability comparable or higher than that of amodiaquine. Computational studies indicate a unique mode of binding of compound 4 to heme through the HOMO located on a biphenyl moeity, which may partly explain the high antiplasmodial activity observed for this compound. PMID:26473363

  20. Contrasting ex vivo efficacies of "reversed chloroquine" compounds in chloroquine-resistant Plasmodium falciparum and P. vivax isolates.

    PubMed

    Wirjanata, Grennady; Sebayang, Boni F; Chalfein, Ferryanto; Prayoga; Handayuni, Irene; Noviyanti, Rintis; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Burgess, Steven J; Peyton, David H; Price, Ric N; Marfurt, Jutta

    2015-09-01

    Chloroquine (CQ) has been the mainstay of malaria treatment for more than 60 years. However, the emergence and spread of CQ resistance now restrict its use to only a few areas where malaria is endemic. The aim of the present study was to investigate whether a novel combination of a CQ-like moiety and an imipramine-like pharmacophore can reverse CQ resistance ex vivo. Between March to October 2011 and January to September 2013, two "reversed chloroquine" (RCQ) compounds (PL69 and PL106) were tested against multidrug-resistant field isolates of Plasmodium falciparum (n = 41) and Plasmodium vivax (n = 45) in Papua, Indonesia, using a modified ex vivo schizont maturation assay. The RCQ compounds showed high efficacy against both CQ-resistant P. falciparum and P. vivax field isolates. For P. falciparum, the median 50% inhibitory concentrations (IC50s) were 23.2 nM for PL69 and 26.6 nM for PL106, compared to 79.4 nM for unmodified CQ (P < 0.001 and P = 0.036, respectively). The corresponding values for P. vivax were 19.0, 60.0, and 60.9 nM (P < 0.001 and P = 0.018, respectively). There was a significant correlation between IC50s of CQ and PL69 (Spearman's rank correlation coefficient [r s] = 0.727, P < 0.001) and PL106 (rs = 0.830, P < 0.001) in P. vivax but not in P. falciparum. Both RCQs were equally active against the ring and trophozoite stages of P. falciparum, but in P. vivax, PL69 and PL106 showed less potent activity against trophozoite stages (median IC50s, 130.2 and 172.5 nM) compared to ring stages (median IC50s, 17.6 and 91.3 nM). RCQ compounds have enhanced ex vivo activity against CQ-resistant clinical isolates of P. falciparum and P. vivax, suggesting the potential use of reversal agents in antimalarial drug development. Interspecies differences in RCQ compound activity may indicate differences in CQ pharmacokinetics between the two Plasmodium species. PMID:26149984

  1. Imported chloroquine-resistant Plasmodium vivax in Singapore: case report and literature review.

    PubMed

    Lim, Poh Lian; Mok, Ying Juan; Lye, David C; Leo, Yee Sin

    2010-01-01

    Chloroquine-resistant Plasmodium vivax (CRPV) infection is emerging as a clinically significant problem. Detailed travel history is crucial to the management of imported malarial cases. We report a 58-year-old business traveler who returned from Indonesia and experienced relapse due to CRPV. The epidemiology and diagnostic challenges of CRPV for travel medicine clinicians are reviewed. PMID:20074103

  2. Survey of chloroquine-resistant mutations in the Plasmodium falciparum pfcrt and pfmdr-1 genes in Hadhramout, Yemen.

    PubMed

    Bamaga, Omar A A; Mahdy, Mohammed A K; Lim, Yvonne A L

    2015-09-01

    Malaria is still a major public health problem in Yemen. More than 95% of the malaria cases are due to Plasmodium ‎falciparum‎. Recently in Yemen, the antimalarial treatment policy was changed from chloroquine (CQ) to artemisinin combination therapy (ACTs). However, CQ is still available and prescribed in the Yemeni market. The persistence of CQ resistance will be prolonged if the shift to ACT and the simultaneous withdrawal of CQ are not rigorously implemented. The aim of the current survey is to detect chloroquine-resistant mutations in P. falciparum chloroquine-resistance transporter (pfcrt) and P. falciparum multi-drug resistance-1 (pfmdr1) genes. These data will be important for future monitoring and assessment of antimalarial drug policy in Yemen. Blood specimens were collected from 735 individuals from different districts of the Hadhramout province, Yemen by house-to-house visit. Mutation-specific nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) methods were used to investigate the mutations in the pfmdr1(codons 86 and 1246) and pfcrt (codons 76, 271, 326, 356 and 371) genes. The overall prevalence of pfcrt mutations at codons 76, 271, 326 and 371 were 50.4%, 58.7%, 54.3% and 44.9%, respectively. All isolates had wild-type pfcrt 356 allele. The majority of pfmdr1 86 alleles (83.3%) and all pfmdr1 1246 alleles were wild type. There was no association between pfcrt mutations and symptomatology, gender and age groups. In conclusion, point mutations in codons 76, 271, 326 and 371 of pfcrt of P. falciparum are high suggesting a sustained high CQ resistance even after 4 years of shifting to ACTs. These findings warrant complete withdrawal of CQ use from the Yemeni market for P. falciparum and careful usage of CQ for treating Plasmodium vivax. PMID:26001972

  3. Return of chloroquine-sensitive Plasmodium falciparum parasites and emergence of chloroquine-resistant Plasmodium vivax in Ethiopia

    PubMed Central

    2014-01-01

    Background Increased resistance by Plasmodium falciparum parasites led to the withdrawal of the antimalarial drugs chloroquine and sulphadoxine-pyrimethamine in Ethiopia. Since 2004 artemether-lumefantrine has served to treat uncomplicated P. falciparum malaria. However, increasing reports on delayed parasite clearance to artemisinin opens up a new challenge in anti-malarial therapy. With the complete withdrawal of CQ for the treatment of Plasmodium falciparum malaria, this study assessed the evolution of CQ resistance by investigating the prevalence of mutant alleles in the pfmdr1 and pfcrt genes in P. falciparum and pvmdr1 gene in Plasmodium vivax in Southern and Eastern Ethiopia. Methods Of the 1,416 febrile patients attending primary health facilities in Southern Ethiopia, 329 febrile patients positive for P. falciparum or P. vivax were recruited. Similarly of the 1,304 febrile patients from Eastern Ethiopia, 81 febrile patients positive for P. falciparum or P. vivax were included in the study. Of the 410 finger prick blood samples collected from malaria patients, we used direct sequencing to investigate the prevalence of mutations in pfcrt and pfmdr1. This included determining the gene copy number in pfmdr1 in 195 P. falciparum clinical isolates, and mutations in the pvmdr1 locus in 215 P. vivax clinical isolates. Results The pfcrt K76 CQ-sensitive allele was observed in 84.1% of the investigated P.falciparum clinical isolates. The pfcrt double mutations (K76T and C72S) were observed less than 3%. The pfcrt SVMNT haplotype was also found to be present in clinical isolates from Ethiopia. The pfcrt CVMNK-sensitive haplotypes were frequently observed (95.9%). The pfmdr1 mutation N86Y was observed only in 14.9% compared to 85.1% of the clinical isolates that carried sensitive alleles. Also, the sensitive pfmdr1 Y184 allele was more common, in 94.9% of clinical isolates. None of the investigated P. falciparum clinical isolates carried S1034C, N1042D and D1246Y

  4. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras.

    PubMed

    Fontecha, Gustavo A; Sanchez, Ana L; Mendoza, Meisy; Banegas, Engels; Mejía-Torres, Rosa E

    2014-07-01

    Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt "CVMNK" genotype in codons 72-76. PMID:25075788

  5. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras

    PubMed Central

    Fontecha, Gustavo A; Sanchez, Ana L; Mendoza, Meisy; Banegas, Engels; Mejía-Torres, Rosa E

    2014-01-01

    Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76. PMID:25075788

  6. Chloroquine resistance in Pakistan and the upsurge of falciparum malaria in Pakistani and Afghan refugee populations.

    PubMed

    Shah, I; Rowland, M; Mehmood, P; Mujahid, C; Razique, F; Hewitt, S; Durrani, N

    1997-09-01

    Surveys conducted in Pakistan during the last decade show that falciparum malaria has become resistant to chloroquine in Pakistani and Afghan refugee populations throughout the country. Although RI resistance is common everywhere (with a frequency of 30%-84%), RII is rarer (2%-36%), and RIII resistance has yet to be detected. The national policy is to prescribe chloroquine as first-line treatment of malaria. A repeated in-vivo survey in a sentinel village indicated that prescription of chloroquine can lead to a 15% increase in the frequency of resistance in a single year, and similar trends were observed in other districts. Coinciding with the spread of resistance is a 6-fold increase in the number of falciparum cases recorded nationally between 1982 and 1992 and a parallel, 5-fold increase in the number of cases recorded in the Afghan refugee population. Resistance contributes to this trend in various ways. Firstly, patients with resistant malaria make repeated visits to health centres. In the sentinel village, for example, where resistance was measured at 71%, recrudescent infections inflated by 66% the genuine incidence of new infections recorded at the health centre. Secondly, owing to ineffective treatment, resistant infections are often still patent during the post-transmission season. This may enlarge the 'overwintering' parasite reservoir, leading to a surge of new cases when transmission resumes. Other factors potentially contributing to the upsurge in falciparum include the decrease availability of insecticide for indoor spraying. Despite the problems posed by resistance for case management, the evidence from the vector-control programme among the refugees is that malaria control through well-targeted campaigns of insecticide spraying is still able to reduce the incidence of falciparum malaria to a level that existed before the advent of resistance. PMID:9425361

  7. Discovering Thiamine Transporters as Targets of Chloroquine Using a Novel Functional Genomics Strategy

    PubMed Central

    Huang, Zhiwei; Srinivasan, Sankaranarayanan; Zhang, Jianhuai; Chen, Kaifu; Li, Yongxiang; Li, Wei; Quiocho, Florante A.; Pan, Xuewen

    2012-01-01

    Chloroquine (CQ) and other quinoline-containing antimalarials are important drugs with many therapeutic benefits as well as adverse effects. However, the molecular targets underlying most such effects are largely unknown. By taking a novel functional genomics strategy, which employs a unique combination of genome-wide drug-gene synthetic lethality (DGSL), gene-gene synthetic lethality (GGSL), and dosage suppression (DS) screens in the model organism Saccharomyces cerevisiae and is thus termed SL/DS for simplicity, we found that CQ inhibits the thiamine transporters Thi7, Nrt1, and Thi72 in yeast. We first discovered a thi3Δ mutant as hypersensitive to CQ using a genome-wide DGSL analysis. Using genome-wide GGSL and DS screens, we then found that a thi7Δ mutation confers severe growth defect in the thi3Δ mutant and that THI7 overexpression suppresses CQ-hypersensitivity of this mutant. We subsequently showed that CQ inhibits the functions of Thi7 and its homologues Nrt1 and Thi72. In particular, the transporter activity of wild-type Thi7 but not a CQ-resistant mutant (Thi7T287N) was completely inhibited by the drug. Similar effects were also observed with other quinoline-containing antimalarials. In addition, CQ completely inhibited a human thiamine transporter (SLC19A3) expressed in yeast and significantly inhibited thiamine uptake in cultured human cell lines. Therefore, inhibition of thiamine uptake is a conserved mechanism of action of CQ. This study also demonstrated SL/DS as a uniquely effective methodology for discovering drug targets. PMID:23209439

  8. Genetic diversity of chloroquine-resistant Plasmodium vivax parasites from the western Brazilian Amazon.

    PubMed

    Lizcano, Omaira Vera; Resende, Sarah Stela; Chehuan, Yonne F; Lacerda, Marcus V G; Brito, Cristiana F A; Zalis, Mariano G

    2014-11-01

    The molecular basis of Plasmodium vivax chloroquine (CQ) resistance is still unknown. Elucidating the molecular background of parasites that are sensitive or resistant to CQ will help to identify and monitor the spread of resistance. By genotyping a panel of molecular markers, we demonstrate a similar genetic variability between in vitro CQ-resistant and sensitive phenotypes of P. vivax parasites. However, our studies identified two loci (MS8 and MSP1-B10) that could be used to discriminate between both CQ-susceptible phenotypes among P. vivax isolates in vitro. These preliminary data suggest that microsatellites may be used to identify and to monitor the spread of P. vivax-resistance around the world. PMID:25411001

  9. Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt

    PubMed Central

    Pelleau, Stéphane; Moss, Eli L.; Dhingra, Satish K.; Volney, Béatrice; Casteras, Jessica; Gabryszewski, Stanislaw J.; Volkman, Sarah K.; Wirth, Dyann F.; Legrand, Eric; Fidock, David A.; Neafsey, Daniel E.; Musset, Lise

    2015-01-01

    In regions with high malaria endemicity, the withdrawal of chloroquine (CQ) as first-line treatment of Plasmodium falciparum infections has typically led to the restoration of CQ susceptibility through the reexpansion of the wild-type (WT) allele K76 of the chloroquine resistance transporter gene (pfcrt) at the expense of less fit mutant alleles carrying the CQ resistance (CQR) marker K76T. In low-transmission settings, such as South America, drug resistance mutations can attain 100% prevalence, thereby precluding the return of WT parasites after the complete removal of drug pressure. In French Guiana, despite the fixation of the K76T allele, the prevalence of CQR isolates progressively dropped from >90% to <30% during 17 y after CQ withdrawal in 1995. Using a genome-wide association study with CQ-sensitive (CQS) and CQR isolates, we have identified a single mutation in pfcrt encoding a C350R substitution that is associated with the restoration of CQ susceptibility. Genome editing of the CQR reference strain 7G8 to incorporate PfCRT C350R caused a complete loss of CQR. A retrospective molecular survey on 580 isolates collected from 1997 to 2012 identified all C350R mutant parasites as being CQS. This mutation emerged in 2002 and rapidly spread throughout the P. falciparum population. The C350R allele is also associated with a significant decrease in piperaquine susceptibility in vitro, suggesting that piperaquine pressure in addition to potential fitness costs associated with the 7G8-type CQR pfcrt allele may have selected for this mutation. These findings have important implications for understanding the evolutionary dynamics of antimalarial drug resistance. PMID:26261345

  10. Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt.

    PubMed

    Pelleau, Stéphane; Moss, Eli L; Dhingra, Satish K; Volney, Béatrice; Casteras, Jessica; Gabryszewski, Stanislaw J; Volkman, Sarah K; Wirth, Dyann F; Legrand, Eric; Fidock, David A; Neafsey, Daniel E; Musset, Lise

    2015-09-15

    In regions with high malaria endemicity, the withdrawal of chloroquine (CQ) as first-line treatment of Plasmodium falciparum infections has typically led to the restoration of CQ susceptibility through the reexpansion of the wild-type (WT) allele K76 of the chloroquine resistance transporter gene (pfcrt) at the expense of less fit mutant alleles carrying the CQ resistance (CQR) marker K76T. In low-transmission settings, such as South America, drug resistance mutations can attain 100% prevalence, thereby precluding the return of WT parasites after the complete removal of drug pressure. In French Guiana, despite the fixation of the K76T allele, the prevalence of CQR isolates progressively dropped from >90% to <30% during 17 y after CQ withdrawal in 1995. Using a genome-wide association study with CQ-sensitive (CQS) and CQR isolates, we have identified a single mutation in pfcrt encoding a C350R substitution that is associated with the restoration of CQ susceptibility. Genome editing of the CQR reference strain 7G8 to incorporate PfCRT C350R caused a complete loss of CQR. A retrospective molecular survey on 580 isolates collected from 1997 to 2012 identified all C350R mutant parasites as being CQS. This mutation emerged in 2002 and rapidly spread throughout the P. falciparum population. The C350R allele is also associated with a significant decrease in piperaquine susceptibility in vitro, suggesting that piperaquine pressure in addition to potential fitness costs associated with the 7G8-type CQR pfcrt allele may have selected for this mutation. These findings have important implications for understanding the evolutionary dynamics of antimalarial drug resistance. PMID:26261345

  11. Prevalence and patterns of antifolate and chloroquine drug resistance markers in Plasmodium vivax across Pakistan

    PubMed Central

    2013-01-01

    Background Plasmodium vivax is the most prevalent malaria species in Pakistan, with a distribution that coincides with Plasmodium falciparum in many parts of the country. Both species are likely exposed to drug pressure from a number of anti-malarials including chloroquine, sulphadoxine-pyrimethamine (SP), and artemisinin combination therapy, yet little is known regarding the effects of drug pressure on parasite genes associated with drug resistance. The aims of this study were to determine the prevalence of polymorphisms in the SP resistance-associated genes pvdhfr, pvdhps and chloroquine resistance-associated gene pvmdr1 in P. vivax isolates collected from across the country. Methods In 2011, 801 microscopically confirmed malaria-parasite positive filter paper blood samples were collected at 14 sites representing four provinces and the capital city of Islamabad. Species-specific polymerase chain reaction (PCR) was used to identify human Plasmodium species infection. PCR-positive P. vivax isolates were subjected to sequencing of pvdhfr, pvdhps and pvmdr1 and to real-time PCR analysis to assess pvmdr1 copy number variation. Results Of the 801 samples, 536 were determined to be P. vivax, 128 were P. falciparum, 43 were mixed vivax/falciparum infections and 94 were PCR-negative for Plasmodium infection. Of PCR-positive P. vivax samples, 372 were selected for sequence analysis. Seventy-six of the isolates (23%) were double mutant at positions S58R and S117N in pvdhfr. Additionally, two mutations at positions N50I and S93H were observed in 55 (15%) and 24 (7%) of samples, respectively. Three 18 base pair insertion-deletions (indels) were observed in pvdhfr, with two insertions at different nucleotide positions in 36 isolates and deletions in 10. Ninety-two percent of samples contained the pvdhps (S382/A383G/K512/A553/V585) SAKAV wild type haplotype. For pvmdr1, all isolates were wild type at position Y976F and 335 (98%) carried the mutation at codon F1076L. All

  12. A focus of high degree chloroquine resistant P. falciparum in Mandla district (M.P.).

    PubMed

    Singh, N; Shukla, M M; Sharma, V P; Saxena, B N

    1989-03-01

    A study on the bioenvironmental control of malaria was launched in Bizadandi block (Mandla district, M.P.) in May 1986. Besides intervention, using environmental management methods and larvivorous fishes, weekly surveillance and chloroquine administration at 25 mg/kg body weight was practiced. Studies during 1987 revealed that a large number of P. falciparum cases did not respond to the standard anti-malarial treatment. Therefore, systematic 28 day in vivo studies were taken up on the follow-up of P. falciparum cases after administration of 3 day course of 25 mg/kg body weight as per the WHO procedure. Results revealed a high proportion of drug resistant cases belonging to RI (237), RII and RIII (182) category. In vivo studies on the sensitivity to metakelfin showed that some cases were resistant to this drug. There is an urgent need to eradicate this focus before it starts spreading to other areas. PMID:2680635

  13. Localized permanent epidemics: the genesis of chloroquine resistance in Plasmodium falciparum.

    PubMed

    Verdrager, J

    1995-03-01

    Localized permanent epidemics occur when, for an indefinite period of time, there is a temporary but continuous introduction of unprotected non-immunes into the same locality of a hyperendemic area. The main epidemiological factors involved in the genesis of localized permanent epidemics were encountered in Pailin (Cambodia) the epicenter of drug resistance in Southeast Asia: a very efficient vector, Anopheles dirus, exophilic and of limited distribution with, therefore, adjacent hyperendemic and non-endemic areas; a permanent pole of attraction in the hyperendemic area: Pailin's sapphires and rubies; a temporary but continuous influx of non-immunes into the pole of attraction: continuous influx of non-immunes into the Pailin gem mining area. In the gem-mining Pailin village drug pressure was considerable: mass drug administration, a medicated salt project and permanent self-medication with very high doses, much higher doses being required to cure non-immunes with heavy infections and severe clinical attacks in epidemic situations. It appears, therefore, that the emergence of chloroquine resistance in Southeast Asia was the consequence of the localized permanent epidemics in Païlin. High level resistance was the result of continuous and intensive serial passages of P. falciparum in the non-immune subjects, large numbers of parasites being exposed to a high level of drug pressure at each passage. Similar epidemiological conditions are encountered in some parts of South America where the exophilic vector is An. nuneztovari. In Colombia, whose eastern mountains bordering Venezuela yield the most highly prized emeralds in the world, chloroquine resistance was detected at about the same time as in Southeast Asia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8525414

  14. [Molecular epidemiology of imported malaria in Italy: the use of genetic markers and in vitro sensitivity test in a study of chloroquine resistance in Plasmodium falciparum].

    PubMed

    Menegon, Michela; Sannella, Anna Rosa; Severini, Carlo; Paglia, Maria Grazia; Matteelli, Alberto; Caramello, Pietro; Severini, Francesco; Taramelli, Donatella; Majori, Giancarlo

    2006-01-01

    The emergence of Plasmodium falciparum drug-resistance, especially chloroquine resistance, represents one of the main obstacles to the control of malaria. Several studies have shown that in P. falciparum the mechanism of chloroquine resistance is linked to specific point mutations in the pfcrt gene of the parasite. In the present study we have analyzed 120 Italian imported malaria cases to evaluate the prevalence of 76T and 220S mutantions in the pfcrt gene. Moreover, the correlation between the presence of pfcrt point mutations and in vitro chloroquine resistance has been evaluated on 25 plasmodial isolates. The results showed a high prevalence of the pfcrt point mutations in isolates analyzed and a significant association between point mutations and in vitro chloroquine resistance. Molecular screening on imported malaria cases can be a useful tool to be employed in surveillance activity and also in monitoring the development and spread of drug resistance in endemic areas. PMID:17033142

  15. Active case detection, treatment of falciparum malaria with combined chloroquine and sulphadoxine/pyrimethamine and vivax malaria with chloroquine and molecular markers of anti-malarial resistance in the Republic of Vanuatu

    PubMed Central

    2010-01-01

    Background Chloroquine-resistant Plasmodium falciparum was first described in the Republic of Vanuatu in the early 1980s. In 1991, the Vanuatu Ministry of Health instituted new treatment guidelines for uncomplicated P. falciparum infection consisting of chloroquine/sulphadoxine-pyrimethamine combination therapy. Chloroquine remains the recommended treatment for Plasmodium vivax. Methods In 2005, cross-sectional blood surveys at 45 sites on Malo Island were conducted and 4,060 adults and children screened for malaria. Of those screened, 203 volunteer study subjects without malaria at the time of screening were followed for 13 weeks to observe peak seasonal incidence of infection. Another 54 subjects with malaria were followed over a 28-day period to determine efficacy of anti-malarial therapy; chloroquine alone for P. vivax and chloroquine/sulphadoxine-pyrimethamine for P. falciparum infections. Results The overall prevalence of parasitaemia by mass blood screening was 6%, equally divided between P. falciparum and P. vivax. Twenty percent and 23% of participants with patent P. vivax and P. falciparum parasitaemia, respectively, were febrile at the time of screening. In the incidence study cohort, after 2,303 person-weeks of follow-up, the incidence density of malaria was 1.3 cases per person-year with P. vivax predominating. Among individuals participating in the clinical trial, the 28-day chloroquine P. vivax cure rate was 100%. The 28-day chloroquine/sulphadoxine-pyrimethamine P. falciparum cure rate was 97%. The single treatment failure, confirmed by merozoite surface protein-2 genotyping, was classified as a day 28 late parasitological treatment failure. All P. falciparum isolates carried the Thr-76 pfcrt mutant allele and the double Asn-108 + Arg-59 dhfr mutant alleles. Dhps mutant alleles were not detected in the study sample. Conclusion Peak seasonal malaria prevalence on Malo Island reached hypoendemic levels during the study observation period. The only in

  16. Chloroquine and Hydroxychloroquine Are Novel Inhibitors of Human Organic Anion Transporting Polypeptide 1A2.

    PubMed

    Xu, Chenghao; Zhu, Ling; Chan, Ting; Lu, Xiaoxi; Shen, Weiyong; Madigan, Michele C; Gillies, Mark C; Zhou, Fanfan

    2016-02-01

    Chloroquine (CQ) and hydroxychloroquine (HCQ) are widely used to treat malaria and inflammatory diseases, long-term usage of which often causes severe side effects, especially retinopathy. Solute carrier transporters (SLCs) are important proteins responsible for the cellular uptake of endogenous and exogenous substances. Inhibitors competing with transporter substrates for SLCs often results in unfavorable toxicities and unsatisfactory therapeutic outcomes. We investigated the inhibitory effect of CQ and HCQ on substrate uptake mediated through a range of important SLC transporters in overexpressing human embryonic kidney (HEK293) cells. Our data revealed that both CQ and HCQ potently inhibit the uptake activity of organic anion transporting polypeptide 1A2 (OATP1A2). We recently reported OATP1A2 to be expressed in human retinal pigment epithelium (RPE), where it mediates cellular uptake of all-trans-retinol (atROL), a key step in the classical visual cycle. In this study, we demonstrate that CQ and HCQ could markedly impair atROL uptake in OATP1A2-expressing HEK293 cells and more importantly, in primary human RPE cells. Our study shows that CQ and HCQ are novel inhibitors of OATP1A2 and significantly impair OATP1A2-mediated substrate uptake, particularly transport of atROL into the RPE. This effect may compromise the function of the classic visual cycle leading to vision impairment and contribute to the retinopathy observed clinically in patients using CQ or HCQ. PMID:26429523

  17. Arguments against Chemoprophylaxis in Areas at Low Risk for Chloroquine-Resistant Plasmodium falciparum.

    PubMed

    Armengaud

    1995-03-01

    Chemoprophylaxis of malaria prevents the disease not the infection (suppressive chemoprophylaxis) with "high levels of confusion and low levels of compliance." The magnitude of danger of contracting malaria for travelers varies in several endemic zones. In West Africa, without prophylaxis, malaria is estimated to have an incidence of 1.4% per person per month. In South and Central America, the incidence is 0.05 and 0.01% per month, respectively. In Asia, the transmission and percentage of infection due to Plasmodium falciparum is much lower. The dangers of chemoprophylaxis in an area at low risk for chloroquine resistant P. falciparum are a reality. Incompletely active drugs change clinical manifestations, and changes in clinical manifestations delay the establishment of a correct diagnosis. The rate of adverse events is 15-20%, and hospitalization due to side effects of prophylaxis occurs in one in 10,000 travelers. Neuropsychiatric side effects have been reported with both mefloquine and chloroquine. A false sense of security can hinder a physician practicing in a nonendemic area from thinking of malaria when a traveler returns with fever. To complicate the picture, in many countries, there is an emerging drug resistance in P. falciparum as well as an emerging chloroquine resistance in P. vivax strains (20% in New Guinea and Irian Jaya). In short, no available chemoprophylaxis is free from toxicity, and its efficacy is never 100%. Alternatives to conventional chemoprophylaxis are encouraged in areas of low morbidity of malaria. In areas where P. vivax occurs primarily, and when the risk of serious side effects from chemoprophylaxis outweighs the risk of life threatening P. falciparum infection, there are four alternative strategies.2,3 The first strategy is that the traveler avoid mosquito bites. With a compulsive attitude, a high degree of protection can be realized with the proper use of pyrethrum-impregnated mosquito netting, topical DEET-containing insect

  18. Transcriptomic Analysis of Chloroquine-Sensitive and Chloroquine-Resistant Strains of Plasmodium falciparum: Toward Malaria Diagnostics and Therapeutics for Global Health.

    PubMed

    Antony, Hiasindh Ashmi; Pathak, Vrushali; Parija, Subhash Chandra; Ghosh, Kanjaksha; Bhattacherjee, Amrita

    2016-07-01

    Increasing drug resistance in Plasmodium falciparum is an important global health burden because it reverses the malarial control achieved so far. Hence, understanding the molecular mechanisms of drug resistance is the epicenter of the development agenda for novel diagnostic and therapeutic (drugs/vaccines) targets for malaria. In this study, we report global comparative transcriptome profiling (RNA-Seq) to characterize the difference in the transcriptome between 48-h intraerythrocytic stage of chloroquine-sensitive and chloroquine-resistant P. falciparum (3D7 and Dd2) strains. The two P. falciparum 3D7 and Dd2 strains have distant geographical origin, the Netherlands and Indochina, respectively. The strains were cultured by an in vitro method and harvested at the 48-h intraerythrocytic stage having 5% parasitemia. The whole transcriptome sequencing was performed using Illumina HiSeq 2500 platform with paired-end reads. The reads were aligned with the reference P. falciparum genome. The alignment percentages for 3D7, Dd2, and Dd2 w/CQ strains were 85.40%, 89.13%, and 84%, respectively. Nearly 40% of the transcripts had known gene function, whereas the remaining genes (about 60%) had unknown function. The genes involved in immune evasion showed a significant difference between the strains. The differential gene expression between the sensitive and resistant strains was measured using the cuffdiff program with the p-value cutoff ≤0.05. Collectively, this study identified differentially expressed genes between 3D7 and Dd2 strains, where we found 89 genes to be upregulated and 227 to be downregulated. On the contrary, for 3D7 and Dd2 w/CQ strains, 45 genes were upregulated and 409 were downregulated. These differentially regulated genes code, by and large, for surface antigens involved in invasion, pathogenesis, and host-parasite interactions, among others. The exhibition of transcriptional differences between these strains of P. falciparum contributes to our

  19. Replication of Plasmodium in reticulocytes can occur without hemozoin formation, resulting in chloroquine resistance.

    PubMed

    Lin, Jing-Wen; Spaccapelo, Roberta; Schwarzer, Evelin; Sajid, Mohammed; Annoura, Takeshi; Deroost, Katrien; Ravelli, Raimond B G; Aime, Elena; Capuccini, Barbara; Mommaas-Kienhuis, Anna M; O'Toole, Tom; Prins, Frans; Franke-Fayard, Blandine M D; Ramesar, Jai; Chevalley-Maurel, Séverine; Kroeze, Hans; Koster, Abraham J; Tanke, Hans J; Crisanti, Andrea; Langhorne, Jean; Arese, Paolo; Van den Steen, Philippe E; Janse, Chris J; Khan, Shahid M

    2015-06-01

    Most studies on malaria-parasite digestion of hemoglobin (Hb) have been performed using P. falciparum maintained in mature erythrocytes, in vitro. In this study, we examine Plasmodium Hb degradation in vivo in mice, using the parasite P. berghei, and show that it is possible to create mutant parasites lacking enzymes involved in the initial steps of Hb proteolysis. These mutants only complete development in reticulocytes and mature into both schizonts and gametocytes. Hb degradation is severely impaired and large amounts of undigested Hb remains in the reticulocyte cytoplasm and in vesicles in the parasite. The mutants produce little or no hemozoin (Hz), the detoxification by-product of Hb degradation. Further, they are resistant to chloroquine, an antimalarial drug that interferes with Hz formation, but their sensitivity to artesunate, also thought to be dependent on Hb degradation, is retained. Survival in reticulocytes with reduced or absent Hb digestion may imply a novel mechanism of drug resistance. These findings have implications for drug development against human-malaria parasites, such as P. vivax and P. ovale, which develop inside reticulocytes. PMID:25941254

  20. Replication of Plasmodium in reticulocytes can occur without hemozoin formation, resulting in chloroquine resistance

    PubMed Central

    Lin, Jing-wen; Spaccapelo, Roberta; Schwarzer, Evelin; Sajid, Mohammed; Annoura, Takeshi; Deroost, Katrien; Ravelli, Raimond B.G.; Aime, Elena; Capuccini, Barbara; Mommaas-Kienhuis, Anna M.; O’Toole, Tom; Prins, Frans; Franke-Fayard, Blandine M.D.; Ramesar, Jai; Chevalley-Maurel, Séverine; Kroeze, Hans; Koster, Abraham J.; Tanke, Hans J.; Crisanti, Andrea; Langhorne, Jean; Arese, Paolo; Van den Steen, Philippe E.; Janse, Chris J.

    2015-01-01

    Most studies on malaria-parasite digestion of hemoglobin (Hb) have been performed using P. falciparum maintained in mature erythrocytes, in vitro. In this study, we examine Plasmodium Hb degradation in vivo in mice, using the parasite P. berghei, and show that it is possible to create mutant parasites lacking enzymes involved in the initial steps of Hb proteolysis. These mutants only complete development in reticulocytes and mature into both schizonts and gametocytes. Hb degradation is severely impaired and large amounts of undigested Hb remains in the reticulocyte cytoplasm and in vesicles in the parasite. The mutants produce little or no hemozoin (Hz), the detoxification by-product of Hb degradation. Further, they are resistant to chloroquine, an antimalarial drug that interferes with Hz formation, but their sensitivity to artesunate, also thought to be dependent on Hb degradation, is retained. Survival in reticulocytes with reduced or absent Hb digestion may imply a novel mechanism of drug resistance. These findings have implications for drug development against human-malaria parasites, such as P. vivax and P. ovale, which develop inside reticulocytes. PMID:25941254

  1. Gametocytocidal and sporontocidal effects of primaquine and of sulfadiazine with pyrimethamine in a chloroquine-resistant strain of Plasmodium falciparum*

    PubMed Central

    Rieckmann, Karl H.; McNamara, James V.; Frischer, Henri; Stockert, Thomas A.; Carson, Paul E.; Powell, Robin D.

    1968-01-01

    Studies with 3 volunteers were conducted to determine the effects of a combination of sulfadiazine and pyrimethamine and the effects of primaquine upon mature gametocytes of a strain of chloroquine-resistant Plasmodium falciparum—the Malayan (Camp.) strain. One volunteer was treated with sulfadiazine and pyrimethamine; two other volunteers each received a single dose of 45 mg of primaquine base. The combination of sulfadiazine and pyrimethamine, although active against blood schizonts, did not exert a marked sporontocidal effect against the Malayan (Camp.) strain. In sharp contrast, primaquine, although not effective as a blood schizontocide, exerted a marked gametocytocidal and sporontocidal effect against this strain. The findings emphasize the need for further studies of the sporontocidal and gametocytocidal effects of drugs, particularly primaquine, against chloroquine-resistant strains of P. falciparum and suggest that primaquine may come to play an important role in preventing the transmission of such strains. PMID:4876731

  2. Detection of chloroquine and artemisinin resistance molecular markers in Plasmodium falciparum: A hospital based study

    PubMed Central

    Ramani, S; Parija, Subhash Chandra; Mandal, Jharna; Hamide, Abdoul; Bhat, Vishnu

    2016-01-01

    Introduction: Emergence of chloroquine (CQ) resistance in Plasmodium falciparum has increased the morbidity and mortality of falciparum malaria worldwide. Artemisinin-based combination therapies are now recommended by the World Health Organization as the first line treatment for falciparum malaria. Numerous molecular markers have been implicated in the CQ and artemisinin resistance. Materials and Methods: A total of 26 confirmed cases of falciparum malaria (by giemsa stained thick and thin smear, quantitative buffy coat, immunochromatographic test, or polymerase chain reaction [PCR]) were included in the study. About 5 ml of ethylenediaminetetraacetic acid blood sample was collected and stored at −20°C till use. Plasmodium DNA was extracted using QIAamp whole blood DNA extraction kit. PCR was done to amplify pfcrt, pfmdr1, pfserca, and pfmrp1 genes and the amplicons obtained were sequenced by Macrogen, Inc., Korea. Single nucleotide polymorphism (SNP) analysis was done using Bio-Edit Sequence Alignment Editor. Results: Out of the four genes targeted, we noted a SNP in the pfcrt gene alone. This SNP (G > T) was noted in the 658th position of the gene, which was seen in 13 patients. The pfmdr1 and pfserca genes were present in 9 and 14 patients respectively. But we could not find any SNPs in these genes. This SNP in pfcrt gene was not significantly associated with any adverse outcome and neither altered disease progression. Conclusion: Presence of a single SNP may not be associated with any adverse clinical outcome. As the sample size was small, we may have not been able to detect any other known or unknown polymorphisms. PMID:26998436

  3. Influence of LAR and VAR on Para-Aminopyridine Antimalarials Targetting Haematin in Chloroquine-Resistance

    PubMed Central

    Warhurst, David C.; Craig, John C.

    2016-01-01

    Antimalarial chloroquine (CQ) prevents haematin detoxication when CQ-base concentrates in the acidic digestive vacuole through protonation of its p-aminopyridine (pAP) basic aromatic nitrogen and sidechain diethyl-N. CQ export through the variant vacuolar membrane export channel, PFCRT, causes CQ-resistance in Plasmodium falciparum but 3-methyl CQ (sontochin SC), des-ethyl amodiaquine (DAQ) and bis 4-aminoquinoline piperaquine (PQ) are still active. This is determined by changes in drug accumulation ratios in parasite lipid (LAR) and in vacuolar water (VAR). Higher LAR may facilitate drug binding to and blocking PFCRT and also aid haematin in lipid to bind drug. LAR for CQ is only 8.3; VAR is 143,482. More hydrophobic SC has LAR 143; VAR remains 68,523. Similarly DAQ with a phenol substituent has LAR of 40.8, with VAR 89,366. In PQ, basicity of each pAP is reduced by distal piperazine N, allowing very high LAR of 973,492, retaining VAR of 104,378. In another bis quinoline, dichlorquinazine (DCQ), also active but clinically unsatisfactory, each pAP retains basicity, being insulated by a 2-carbon chain from a proximal nitrogen of the single linking piperazine. While LAR of 15,488 is still high, the lowest estimate of VAR approaches 4.9 million. DCQ may be expected to be very highly lysosomotropic and therefore potentially hepatotoxic. In 11 pAP antimalarials a quadratic relationship between logLAR and logResistance Index (RI) was confirmed, while log (LAR/VAR) vs logRI for 12 was linear. Both might be used to predict the utility of structural modifications. PMID:27483471

  4. Influence of LAR and VAR on Para-Aminopyridine Antimalarials Targetting Haematin in Chloroquine-Resistance.

    PubMed

    Warhurst, David C; Craig, John C; Raheem, K Saki

    2016-01-01

    Antimalarial chloroquine (CQ) prevents haematin detoxication when CQ-base concentrates in the acidic digestive vacuole through protonation of its p-aminopyridine (pAP) basic aromatic nitrogen and sidechain diethyl-N. CQ export through the variant vacuolar membrane export channel, PFCRT, causes CQ-resistance in Plasmodium falciparum but 3-methyl CQ (sontochin SC), des-ethyl amodiaquine (DAQ) and bis 4-aminoquinoline piperaquine (PQ) are still active. This is determined by changes in drug accumulation ratios in parasite lipid (LAR) and in vacuolar water (VAR). Higher LAR may facilitate drug binding to and blocking PFCRT and also aid haematin in lipid to bind drug. LAR for CQ is only 8.3; VAR is 143,482. More hydrophobic SC has LAR 143; VAR remains 68,523. Similarly DAQ with a phenol substituent has LAR of 40.8, with VAR 89,366. In PQ, basicity of each pAP is reduced by distal piperazine N, allowing very high LAR of 973,492, retaining VAR of 104,378. In another bis quinoline, dichlorquinazine (DCQ), also active but clinically unsatisfactory, each pAP retains basicity, being insulated by a 2-carbon chain from a proximal nitrogen of the single linking piperazine. While LAR of 15,488 is still high, the lowest estimate of VAR approaches 4.9 million. DCQ may be expected to be very highly lysosomotropic and therefore potentially hepatotoxic. In 11 pAP antimalarials a quadratic relationship between logLAR and logResistance Index (RI) was confirmed, while log (LAR/VAR) vs logRI for 12 was linear. Both might be used to predict the utility of structural modifications. PMID:27483471

  5. Chloroquine Is Grossly Under Dosed in Young Children with Malaria: Implications for Drug Resistance

    PubMed Central

    Ursing, Johan; Eksborg, Staffan; Rombo, Lars; Bergqvist, Yngve; Blessborn, Daniel; Rodrigues, Amabelia; Kofoed, Poul-Erik

    2014-01-01

    Background Plasmodium falciparum malaria is treated with 25 mg/kg of chloroquine (CQ) irrespective of age. Theoretically, CQ should be dosed according to body surface area (BSA). The effect of dosing CQ according to BSA has not been determined but doubling the dose per kg doubled the efficacy of CQ in children aged <15 years infected with P. falciparum carrying CQ resistance causing genes typical for Africa. The study aim was to determine the effect of age on CQ concentrations. Methods and Findings Day 7 whole blood CQ concentrations were determined in 150 and 302 children treated with 25 and 50 mg/kg, respectively, in previously conducted clinical trials. CQ concentrations normalised for the dose taken in mg/kg of CQ decreased with decreasing age (p<0.001). CQ concentrations normalised for dose taken in mg/m2 were unaffected by age. The median CQ concentration in children aged <2 years taking 50 mg/kg and in children aged 10–14 years taking 25 mg/kg were 825 (95% confidence interval [CI] 662–988) and 758 (95% CI 640–876) nmol/l, respectively (p = 0.67). The median CQ concentration in children aged 10–14 taking 50 mg/kg and children aged 0–2 taking 25 mg/kg were 1521 and 549 nmol/l. Adverse events were not age/concentration dependent. Conclusions CQ is under-dosed in children and should ideally be dosed according to BSA. Children aged <2 years need approximately double the dose per kg to attain CQ concentrations found in children aged 10–14 years. Clinical trials assessing the efficacy of CQ in Africa are typically performed in children aged <5 years. Thus the efficacy of CQ is typically assessed in children in whom CQ is under dosed. Approximately 3 fold higher drug concentrations can probably be safely given to the youngest children. As CQ resistance is concentration dependent an alternative dosing of CQ may overcome resistance in Africa. PMID:24466245

  6. Interaction between rifampicin, amodiaquine and artemether in mice infected with chloroquine resistant Plasmodium berghei

    PubMed Central

    2014-01-01

    Background Artemisinin-based combination therapy (ACT) remains the most effective chemotherapeutic strategy in the management of malaria. However, reports of reduced susceptibility of Plasmodium falciparum to the ACT justify the need for continued search for alternative anti-malarial drugs. The use of antibiotics with anti-malarial properties represents a potentially valuable chemotherapeutic option for the management of drug resistant infections. Thus, the intrinsic anti-malarial activity of the combination of clinical doses of rifampicin with amodiaquine and artemether was evaluated in an animal model using Plasmodium berghei. Methods A modification of the suppressive tests in vivo was employed. The anti-malarial activity of standard doses of amodiaquine (AQ) with or without artemether (ART) and combined with varying doses of rifampicin (RIF 15 mg/kg or RIF 30 mg/kg body weight) was evaluated in 40 mice sub-divided into eight groups and inoculated intraperitoneally with 1 × 107 red blood cells infected with chloroquine-resistant P. berghei ANKA strain. There were two control groups of animals, one group received amodiaquine alone while the other group received saline. Parasiticidal activity and survival of the animals were assessed over 21 days. Results Parasitaemia in the control animals peaked at 38% on day 9 and all animals died by day 10. The combination of amodiaquine with rifampicin 15 mg/kg body weight was the most effective of all the combinations and more efficacious than amodiaquine alone. The order of superiority of anti-malarial efficacy of the combinations was as follows; AQ + RIF 15 > AQ > AQ + ART + RIF 30 > AQ + ART + RIF 15 > AQ + RIF 30. Conclusion The combination of the clinical dose of rifampicin (15 mg/kg) with amodiaquine represents a potentially valuable treatment option in management of drug resistant malaria. In addition, the role of pharmacokinetic interaction in multiple drug therapy

  7. Chloroquine Phosphate Oral

    MedlinePlus

    ... allergic to chloroquine phosphate, chloroquine hydrochloride (Aralen HCl), hydroxychloroquine (Plaquenil), or any other drugs.tell your doctor ... taking chloroquine phosphate, chloroquine hydrochloride (Aralen HCl), or hydroxychloroquine (Plaquenil).tell your doctor if you are pregnant ...

  8. Chloroquine Phosphate Oral

    MedlinePlus

    ... allergic to chloroquine phosphate, chloroquine hydrochloride (Aralen HCl), hydroxychloroquine (Plaquenil), or any other drugs.tell your doctor and ... taking chloroquine phosphate, chloroquine hydrochloride (Aralen HCl), or hydroxychloroquine (Plaquenil).tell your doctor if you are pregnant ...

  9. Double Mutation in the pfmdr1 Gene Is Associated with Emergence of Chloroquine-Resistant Plasmodium falciparum Malaria in Eastern India

    PubMed Central

    Das, Sabyasachi; Mahapatra, Santanu Kar; Tripathy, Satyajit; Chattopadhyay, Sourav; Dash, Sandeep Kumar; Mandal, Debasis; Das, Balaram; Hati, Amiya Kumar

    2014-01-01

    Malaria is a major public health problem in tropical and subtropical countries, including India. This study elucidates the cause of chloroquine treatment failure (for Plasmodium falciparum infection) before the introduction of artemisinin combination therapy. One hundred twenty-six patients were randomized to chloroquine treatment, and the therapeutic efficacy was monitored from days 1 to 28. An in vitro susceptibility test was performed with all isolates. Parasitic DNA was isolated, followed by PCR and restriction digestion of different codons of the pfcrt gene (codons 72 to 76) and the pfmdr1 gene (N86Y, Y184F, S1034C, N1042D, and D1246Y). Finally, sequencing was done to confirm the mutations. Forty-three (34.13%) early treatment failure cases and 16 (12.69%) late treatment failure cases were observed after chloroquine treatment. In vitro chloroquine resistance was found in 103 isolates (81.75%). Twenty-six (60.47%) early treatment failure cases and 6 (37.5%) late treatment failure cases were associated with the CVMNK-YYSNY allele (the underlined amino acids are those that were mutated). Moreover, the CVIEK-YYSNY allele was found in 8 early treatment failure (18.60%) and 2 late treatment failure (12.5%) cases. The presence of the wild-type pfcrt (CVMNK) and pfmdr1 (YYSNY) double mutant allele in chloroquine-nonresponsive cases was quite uncommon. In vivo chloroquine treatment failure and in vitro chloroquine resistance were strongly correlated with the CVMNK-YYSNY and CVIEK-YYSNY haplotypes (P < 0.01). PMID:25070111

  10. Comparison of in vivo and in vitro tests of resistance in patients treated with chloroquine in Yaoundé, Cameroon.

    PubMed Central

    Ringwald, P.; Basco, L. K.

    1999-01-01

    The usefulness of an isotopic in vitro assay in the field was evaluated by comparing its results with the therapeutic response determined by the simplified WHO in vivo test in symptomatic Cameroonian patients treated with chloroquine. Of the 117 enrolled patients, 102 (87%) completed the 14-day follow-up, and 95 isolates obtained from these patients (46 children, 49 adults) yielded an interpretable in vitro test. A total of 57 of 95 patients (60%; 28 children and 29 adults) had an adequate clinical response with negative smears (n = 46) or with an asymptomatic parasitaemia (n = 11) on day 7 and/or day 14. The geometric mean 50% inhibitory concentration of the isolates obtained from these patients was 63.3 nmol/l. Late and early treatment failure was observed in 29 (30.5%) and 9 (9.5%) patients, respectively. The geometric mean 50% inhibitory concentrations of the corresponding isolates were 173 nmol/l and 302 nmol/l. Among the patients responding with late and early treatment failure, five isolates and one isolate, respectively, yielded a discordant result (in vivo resistance and in vitro sensitivity). The sensitivity, specificity, and predictive value of the in vitro test to detect chloroquine-sensitive cases was 67%, 84% and 86%, respectively. There was moderate concordance between the in vitro and in vivo tests (kappa value = 0.48). The in vitro assay agrees relatively well with the therapeutic response and excludes several host factors that influence the results of the in vivo test. However, in view of some discordant results, the in vitro test cannot substitute for in vivo data on therapeutic efficacy. The only reliable definition of "resistance" in malaria parasites is based on clinical and parasitological response in symptomatic patients, and the in vivo test provides the standard method to determine drug sensitivity or resistance as well as to guide national drug policies. PMID:10063659

  11. Nonradioactive heteroduplex tracking assay for the detection of minority-variant chloroquine-resistant Plasmodium falciparum in Madagascar

    PubMed Central

    Juliano, Jonathan J; Randrianarivelojosia, Milijaona; Ramarosandratana, Benjamin; Ariey, Frédéric; Mwapasa, Victor; Meshnick, Steven R

    2009-01-01

    Background Strains of Plasmodium falciparum genetically resistant to chloroquine (CQ) due to the presence of pfcrt 76T appear to have been recently introduced to the island of Madagascar. The prevalence of such resistant genotypes is reported to be low (< 3%) when evaluated by conventional PCR. However, these methods are insensitive to low levels of mutant parasites present in patients with polyclonal infections. Thus, the current estimates may be an under representation of the prevalence of the CQ-resistant P. falciparum isolates on the island. Previously, minority variant chloroquine resistant parasites were described in Malawian patients using an isotopic heteroduplex tracking assay (HTA), which can detect pfcrt 76T-bearing P. falciparum minority variants in individual patients that were undetectable by conventional PCR. However, as this assay required a radiolabeled probe, it could not be used in many resource-limited settings. Methods This study describes a digoxigenin (DIG)-labeled chemiluminescent heteroduplex tracking assay (DIG-HTA) to detect pfcrt 76T-bearing minority variant P. falciparum. This assay was compared to restriction fragment length polymorphism (RFLP) analysis and to the isotopic HTA for detection of genetically CQ-resistant parasites in clinical samples. Results Thirty one clinical P. falciparum isolates (15 primary isolates and 16 recurrent isolates) from 17 Malagasy children treated with CQ for uncomplicated malaria were genotyped for the pfcrt K76T mutation. Two (11.7%) of 17 patients harboured genetically CQ-resistant P. falciparum strains after therapy as detected by HTA. RFLP analysis failed to detect any pfcrt K76T-bearing isolates. Conclusion These findings indicate that genetically CQ-resistant P. falciparum are more common than previously thought in Madagascar even though the fitness of the minority variant pfcrt 76T parasites remains unclear. In addition, HTAs for malaria drug resistance alleles are promising tools for the

  12. The Association of K76T Mutation in Pfcrt Gene and Chloroquine Treatment Failure in Uncomplicated Plasmodium falciparum Malaria in a Cohort of Nigerian Children

    NASA Astrophysics Data System (ADS)

    Umar, R. A.; Hassan, S. W.; Ladan, M. J.; Nma Jiya, M.; Abubakar, M. K.; Nata`Ala, U.

    The aim of this study was to evaluate the association of K76T mutation in Pfcrt gene and chloroquine treatment failure following reports that the efficacy of chloroquine in the treatment of uncomplicated falciparum malaria in Africa is seriously compromised by high levels of drug resistance. The occurrence of mutation on codon 76 of Plasmodium falciparum chloroquine resistance transporter (Pfcrt) gene has been associated with development of resistance to chloroquine. We investigated the association of K76T mutation in Pfcrt gene in malaria-infected blood samples from a cohort of Nigerian children with uncomplicated falciparum malaria treated with chloroquine and its association with clinical (in vivo) resistance. The Pfcrt T76 allele was very significantly associated with resistance to chloroquine (Fischer exact test: p = 0.0001). We conclude that K76T mutation in Pfcrt gene is significantly associated with chloroquine resistance and that it could be used as a population marker for chloroquine resistance in this part of the country

  13. Discovery of a selective, safe and novel anti-malarial compound with activity against chloroquine resistant strain of Plasmodium falciparum

    PubMed Central

    Agarwal, Ankita; Paliwal, Sarvesh; Mishra, Ruchi; Sharma, Swapnil; Kumar Dwivedi, Anil; Tripathi, Renu; Gunjan, Sarika

    2015-01-01

    In recent years the DNA minor groove has attracted much attention for the development of anti-malarial agents. In view of this we have attempted to discover novel DNA minor groove binders through in-silico and in-vitro workflow. A rigorously validated pharmacophore model comprising of two positive ionizable (PI), one hydrophobic (HY) and one ring aromatic (RA) features was used to mine NCI chemical compound database. This led to retrieval of many hits which were screened on the basis of estimated activity, fit value and Lipinski’s violation. Finally two compounds NSC639017 and NSC371488 were evaluated for their in-vitro anti-malarial activities against Plasmodium falciparum 3D7 (CQ sensitive) and K1 (CQ resistant) strains by SYBR green-I based fluorescence assay. The results revealed that out of two, NSC639017 posses excellent anti-malarial activity particularly against chloroquine resistant strain and moreover NSC639017 also appeared to be safe (CC50 126.04 μg/ml) and selective during cytotoxicity evaluation. PMID:26346444

  14. Monitoring of malaria parasite resistance to chloroquine and sulphadoxine-pyrimethamine in the Solomon Islands by DNA microarray technology

    PubMed Central

    2010-01-01

    Background Little information is available on resistance to anti-malarial drugs in the Solomon Islands (SI). The analysis of single nucleotide polymorphisms (SNPs) in drug resistance associated parasite genes is a potential alternative to classical time- and resource-consuming in vivo studies to monitor drug resistance. Mutations in pfmdr1 and pfcrt were shown to indicate chloroquine (CQ) resistance, mutations in pfdhfr and pfdhps indicate sulphadoxine-pyrimethamine (SP) resistance, and mutations in pfATPase6 indicate resistance to artemisinin derivatives. Methods The relationship between the rate of treatment failure among 25 symptomatic Plasmodium falciparum-infected patients presenting at the clinic and the pattern of resistance-associated SNPs in P. falciparum infecting 76 asymptomatic individuals from the surrounding population was investigated. The study was conducted in the SI in 2004. Patients presenting at a local clinic with microscopically confirmed P. falciparum malaria were recruited and treated with CQ+SP. Rates of treatment failure were estimated during a 28-day follow-up period. In parallel, a DNA microarray technology was used to analyse mutations associated with CQ, SP, and artemisinin derivative resistance among samples from the asymptomatic community. Mutation and haplotype frequencies were determined, as well as the multiplicity of infection. Results The in vivo study showed an efficacy of 88% for CQ+SP to treat P. falciparum infections. DNA microarray analyses indicated a low diversity in the parasite population with one major haplotype present in 98.7% of the cases. It was composed of fixed mutations at position 86 in pfmdr1, positions 72, 75, 76, 220, 326 and 356 in pfcrt, and positions 59 and 108 in pfdhfr. No mutation was observed in pfdhps or in pfATPase6. The mean multiplicity of infection was 1.39. Conclusion This work provides the first insight into drug resistance markers of P. falciparum in the SI. The obtained results indicated the

  15. Multiple Origins of Mutations in the mdr1 Gene—A Putative Marker of Chloroquine Resistance in P. vivax

    PubMed Central

    Schousboe, Mette L.; Ranjitkar, Samir; Rajakaruna, Rupika S.; Amerasinghe, Priyanie H.; Morales, Francisco; Pearce, Richard; Ord, Rosalyn; Leslie, Toby; Rowland, Mark; Gadalla, Nahla B.; Konradsen, Flemming; Bygbjerg, Ib C.; Roper, Cally; Alifrangis, Michael

    2015-01-01

    Background Chloroquine combined with primaquine has been the recommended antimalarial treatment of Plasmodium vivax malaria infections for six decades but the efficacy of this treatment regimen is threatened by chloroquine resistance (CQR). Single nucleotide polymorphisms (SNPs) in the multidrug resistance gene, Pvmdr1 are putative determinants of CQR but the extent of their emergence at population level remains to be explored. Objective In this study we describe the prevalence of SNPs in the Pvmdr1 among samples collected in seven P. vivax endemic countries and we looked for molecular evidence of drug selection by characterising polymorphism at microsatellite (MS) loci flanking the Pvmdr1 gene. Methods We examined the prevalence of SNPs in the Pvmdr1 gene among 267 samples collected from Pakistan, Afghanistan, Sri Lanka, Nepal, Sudan, São Tomé and Ecuador. We measured and diversity in four microsatellite (MS) markers flanking the Pvmdr1 gene to look evidence of selection on mutant alleles. Results SNP polymorphism in the Pvmdr1 gene was largely confined to codons T958M, Y976F and F1076L. Only 2.4% of samples were wildtype at all three codons (TYF, n = 5), 13.3% (n = 28) of the samples were single mutant MYF, 63.0% of samples (n = 133) were double mutant MYL, and 21.3% (n = 45) were triple mutant MFL. Clear geographic differences in the prevalence of these Pvmdr mutation combinations were observed. Significant linkage disequilibrium (LD) between Pvmdr1 and MS alleles was found in populations sampled in Ecuador, Nepal and Sri Lanka, while significant LD between Pvmdr1 and the combined 4 MS locus haplotype was only seen in Ecuador and Sri Lanka. When combining the 5 loci, high level diversity, measured as expected heterozygosity (He), was seen in the complete sample set (He = 0.99), while He estimates for individual loci ranged from 0.00–0.93. Although Pvmdr1 haplotypes were not consistently associated with specific flanking MS alleles, there was significant

  16. Antiplasmodial properties of kaempferol-3-O-rhamnoside isolated from the leaves of Schima wallichii against chloroquine-resistant Plasmodium falciparum

    PubMed Central

    BARLIANA, MELISA I.; SURADJI, EKA W.; ABDULAH, RIZKY; DIANTINI, AJENG; HATABU, TOSHIMITSU; NAKAJIMA-SHIMADA, JUNKO; SUBARNAS, ANAS; KOYAMA, HIROSHI

    2014-01-01

    Previous intervention studies have shown that the most effective agents used in the treatment of malaria were isolated from natural sources. Plants consumed by non-human primates serve as potential drug sources for human disease management due to the similarities in anatomy, physiology and disease characteristics. The present study investigated the antiplasmodial properties of the primate-consumed plant, Schima wallichii (S. wallichii) Korth. (family Theaceae), which has already been reported to have several biological activities. The ethanol extract of S. wallichii was fractionated based on polarity using n-hexane, ethyl acetate and water. The antiplasmodial activity was tested in vitro against chloroquine-resistant Plasmodium falciparum (P. falciparum) at 100 μg/ml for 72 h. The major compound of the most active ethyl acetate fraction was subsequently isolated using column chromatography and identified by nuclear magnetic resonance. The characterized compound was also tested against chloroquine-resistant P. falciparum in culture to evaluate its antiplasmodial activity. The ethanol extract of S. wallichii at 100 μg/ml exhibited a significant parasite shrinkage after 24 h of treatment. The ethyl acetate fraction at 100 μg/ml was the most active fraction against chloroquine-resistant P. falciparum. Based on the structural characterization, the major compound isolated from the ethyl acetate fraction was kaempferol-3-O-rhamnoside, which showed promising antiplasmodial activity against chloroquine-resistant P. falciparum with an IC50 of 106 μM after 24 h of treatment. The present study has provided a basis for the further investigation of kaempferol-3-O-rhamnoside as an active compound for potential antimalarial therapeutics. PMID:24944812

  17. 4-Aminoquinolines Active against Chloroquine-Resistant Plasmodium falciparum: Basis of Antiparasite Activity and Quantitative Structure-Activity Relationship Analyses▿

    PubMed Central

    Hocart, Simon J.; Liu, Huayin; Deng, Haiyan; De, Dibyendu; Krogstad, Frances M.; Krogstad, Donald J.

    2011-01-01

    Chloroquine (CQ) is a safe and economical 4-aminoquinoline (AQ) antimalarial. However, its value has been severely compromised by the increasing prevalence of CQ resistance. This study examined 108 AQs, including 68 newly synthesized compounds. Of these 108 AQs, 32 (30%) were active only against CQ-susceptible Plasmodium falciparum strains and 59 (55%) were active against both CQ-susceptible and CQ-resistant P. falciparum strains (50% inhibitory concentrations [IC50s], ≤25 nM). All AQs active against both CQ-susceptible and CQ-resistant P. falciparum strains shared four structural features: (i) an AQ ring without alkyl substitution, (ii) a halogen at position 7 (Cl, Br, or I but not F), (iii) a protonatable nitrogen at position 1, and (iv) a second protonatable nitrogen at the end of the side chain distal from the point of attachment to the AQ ring via the nitrogen at position 4. For activity against CQ-resistant parasites, side chain lengths of ≤3 or ≥10 carbons were necessary but not sufficient; they were identified as essential factors by visual comparison of 2-dimensional (2-D) structures in relation to the antiparasite activities of the AQs and were confirmed by computer-based 3-D comparisons and differential contour plots of activity against P. falciparum. The advantage of the method reported here (refinement of quantitative structure-activity relationship [QSAR] descriptors by random assignment of compounds to multiple training and test sets) is that it retains QSAR descriptors according to their abilities to predict the activities of unknown test compounds rather than according to how well they fit the activities of the compounds in the training sets. PMID:21383099

  18. Ultrasonic chorioretinopathy: a chloroquine vs control study.

    PubMed

    Kaplan, L J; Holasek, E

    1983-12-01

    High frequency ultrasound was used to produce chorioretinal lesions in two groups of pigmented rabbits. The control group received no medications. The other group was treated with subretinotoxic doses of chloroquine. Our experiment showed that the untreated group developed focal chorioretinal lesions and ricochet lesions at lower energies than did the chloroquinated group. We postulated that chloroquine, a melanin binding drug, altered melanin's ability to process ultrasonic energy by sonic-thermal conversion. This work suggests that chloroquine, even in subretinotoxic doses, may still exert an effect on the retina by chemically binding melanin and preventing its function as an energy transport system. PMID:6660693

  19. Antiplasmodial activity-aided isolation and identification of quercetin-4'-methyl ether in Chromolaena odorata leaf fraction with high activity against chloroquine-resistant Plasmodium falciparum.

    PubMed

    Ezenyi, I C; Salawu, O A; Kulkarni, R; Emeje, M

    2014-12-01

    The present study was undertaken to evaluate the antiplasmodial activity of Chromolaena odorata leaf extract and gradient fractions through in vivo and in vitro tests, aimed at identifying its antiplasmodial constituents. Sub-fractions obtained from the most active gradient fraction were further tested for cytotoxicity against THP-1 cells, chloroquine-sensitive (HB3) and chloroquine-resistant (FCM29) Plasmodium falciparum. Our results showed the dichloromethane gradient fraction was most effective, significantly (P < 0.05) suppressing infection by 99.46% at 100 mg/kg body weight. Amongst its 13 sub-fractions (DF1-DF13), DF11 was highly active, with IC50 of 4.8 and 6.74 μg/ml against P. falciparum HB3 and FCM29, respectively. Cytotoxicity of DF11 was estimated to be above 50 μg/ml, and its separation by column chromatography yielded a flavonoid which was characterized as 3, 5, 7, 3' tetrahydroxy-4'-methoxyflavone from its spectroscopic data. It significantly suppressed infection (65.43-81.48%) in mice at 2.5-5 mg/kg doses and compared favourably with the effects of chloroquine and artemisinin. It may therefore serve as a useful phytochemical and antiplasmodial activity marker of C. odorata leaves, which exhibit potential for development as medicine against malaria. PMID:25199554

  20. Chloroquine Clinical Failures in P. falciparum Malaria Are Associated with Mutant Pfmdr-1, Not Pfcrt in Madagascar

    PubMed Central

    Andriantsoanirina, Valérie; Ratsimbasoa, Arsène; Bouchier, Christiane; Tichit, Magali; Jahevitra, Martial; Rabearimanana, Stéphane; Raherinjafy, Rogelin; Mercereau-Puijalon, Odile; Durand, Rémy; Ménard, Didier

    2010-01-01

    Molecular studies have demonstrated that mutations in the Plasmodium falciparum chloroquine resistance transporter gene (Pfcrt) play a major role in chloroquine resistance, while mutations in P. falciparum multidrug resistance gene (Pfmdr-1) act as modulator. In Madagascar, the high rate of chloroquine treatment failure (44%) appears disconnected from the overall level of in vitro CQ susceptibility (prevalence of CQ-resistant parasites <5%) or Pfcrt mutant isolates (<1%), strongly contrasting with sub-Saharan African countries. Previous studies showed a high frequency of Pfmdr-1 mutant parasites (>60% of isolates), but did not explore their association with P. falciparum chloroquine resistance. To document the association of Pfmdr-1 alleles with chloroquine resistance in Madagascar, 249 P. falciparum samples collected from patients enrolled in a chloroquine in vivo efficacy study were genotyped in Pfcrt/Pfmdr-1 genes as well as the estimation of the Pfmdr-1 copy number. Except 2 isolates, all samples displayed a wild-type Pfcrt allele without Pfmdr-1 amplification. Chloroquine treatment failures were significantly associated with Pfmdr-1 86Y mutant codon (OR = 4.6). The cumulative incidence of recurrence of patients carrying the Pfmdr-1 86Y mutation at day 0 (21 days) was shorter than patients carrying Pfmdr-1 86N wild type codon (28 days). In an independent set of 90 selected isolates, in vitro susceptibility to chloroquine was not associated with Pfmdr-1 polymorphisms. Analysis of two microsatellites flanking Pfmdr-1 allele showed that mutations occurred on multiple genetic backgrounds. In Madagascar, Pfmdr-1 polymorphism is associated with late chloroquine clinical failures and unrelated with in vitro susceptibility or Pfcrt genotype. These results highlight the limits of the current in vitro tests routinely used to monitor CQ drug resistance in this unique context. Gaining insight about the mechanisms that regulate polymorphism in Pfmdr1 remains important

  1. Analysis of gene mutations involved in chloroquine resistance in Plasmodium falciparum parasites isolated from patients in the southwest of Saudi Arabia

    PubMed Central

    Bin Dajem, Saad M.; Al-Qahtani, Ahmed

    2010-01-01

    BACKGROUND AND OBJECTIVES: Chloroquine has been the drug of choice for the treatment of malaria for many decades. We aimed to examine the molecular basis of chloroquine resistance among Plasmodium falciparum isolates from the southwestern region of Saudi Arabia by analyzing the K76T and N86Y mutations in the PfCRT and PfMDR1 genes, respectively. PATIENTS AND METHODS: P falciparum-infected blood spot samples (n=121) were collected on filter papers. DNA was extracted and fragments from the above genes were amplified using nested PCR. The amplicons were digested by ApoI enzyme and sequenced. RESULTS: Of the 121 samples, 95 and 112 samples could be amplified for PfCRT K76T and PfMDR1 N86Y mutations, respectively. All of the samples amplified for the PfCRT K76T mutation were undigestible by ApoI, suggesting the presence of the K76T mutation. For the PfMDR1 N86Y mutation, 65/109 samples (59.6%) were digestible when treated with ApoI in a pattern, suggestive of the presence of the investigated wild allele (N86). However, 44/109 samples (40.4%) were digestible by ApoI, suggesting the presence of the mutated allele (Y) at position 86. DNA sequencing confirmed these results. CONCLUSION: Surprisingly, all isolates exhibited the mutated allele at codon 76 (K76T) of PfCRT. However, the mutated mutant allele at codon 86 (N86Y) of PfMDR1 was found in 40.4% of the samples studied. To our knowledge, this is the first study that has investigated the existence of the mutation in the PfMDR1 gene in the country. This study will contribute to the development of new strategies for therapeutic intervention against malaria in Saudi Arabia. PMID:20427933

  2. Similar Efficacy and Tolerability of Double-Dose Chloroquine and Artemether-Lumefantrine for Treatment of Plasmodium falciparum Infection in Guinea-Bissau: A Randomized Trial

    PubMed Central

    Kofoed, Poul-Erik; Rodrigues, Amabelia; Blessborn, Daniel; Thoft-Nielsen, Rikke; Björkman, Anders; Rombo, Lars

    2011-01-01

    Background. In 2008, Guinea-Bissau introduced artemether-lumefantrine for treatment of uncomplicated malaria. Previously, 3 times the standard dose of chloroquine, that was probably efficacious against Plasmodium falciparum with the resistance-associated chloroquine-resistance transporter (pfcrt) 76T allele, was routinely used. The present study compared the efficacy and tolerability of a double standard dose of chloroquine with the efficacy and tolerability of artemether-lumefantrine. Methods. In a randomized open-label clinical trial, artemether-lumefantrine or chloroquine (50 mg/kg) were given as 6 divided doses over 3 days to children aged 6 months - 15 years who had uncomplicated P. falciparum monoinfection. Drug concentrations were measured on day 7. P. falciparum multidrug resistance gene N86Y and pfcrt K76T alleles were identified. Results. The polymerase chain reaction–adjusted day 28 and 42 treatment efficacies were 162 (97%) of 168 and 155 (97%) of 161, respectively, for artemether-lumefantrine and 150 (95%) of 158 and 138 (94%) of 148, respectively, for chloroquine. When parasites with resistance-associated pfcrt 76T were treated, the day 28 efficacy of chloroquine was 87%. No severe drug-related adverse events were detected. Symptom resolution was similar with both treatments. Conclusions. Both treatments achieved the World Health Organization–recommended efficacy for antimalarials that will be adopted as policy. High-dose chloroquine treatment regimes should be further evaluated with the aim of assessing chloroquine as a potential partner drug to artemisinin derivatives. Clinical trials registration. NCT00426439 PMID:21148503

  3. Accident resistant transport container

    DOEpatents

    Andersen, John A.; Cole, James K.

    1980-01-01

    The invention relates to a container for the safe air transport of plutonium having several intermediate wood layers and a load spreader intermediate an inner container and an outer shell for mitigation of shock during a hypothetical accident.

  4. Accident resistant transport container

    DOEpatents

    Anderson, J.A.; Cole, K.K.

    The invention relates to a container for the safe air transport of plutonium having several intermediate wood layers and a load spreader intermediate an inner container and an outer shell for mitigation of shock during a hypothetical accident.

  5. [Drug resistance of Plasmodium falciparum in Congo. I. In vivo study with 10 and 25 mg/kg of chloroquine (235 tests)].

    PubMed

    Carme, B; Benthein, F; Moudzeo, H; Bitsi, A; Madzou, G

    1986-01-01

    An evaluation of chloroquine resistance in P. falciparum was conducted in four different areas of the People's Republic of the Congo during the months of October and November 1985. Using the simplified seven day in vivo test protocol, 235 tests were completed in 92 children aged three months to five years seen at the Maternal Child Health Clinics (54 children were treated by a single dose at 10 mg/kg and 38 children were treated by the three day dose of 25 mg/kg) and 143 school children aged six to 12 years (70 treated by 10 mg/kg and 73 treated by 25 mg/kg). In three of the zones (Brazzaville, the forest mountains of the Mayombe and Chaillu), a high level of resistance was found in the percentage of children with asexual forms of P. falciparum parasites (1 000 leucocytes) in the blood smears. After 7 days, the percentage of positive results in children treated by 10 mg/kg was found to be 65.5% and 29.3% for children treated by 25 mg/kg. Failure rates, independent of parasite density, were less in school aged children. A significant number of observations seems to be Type II resistance. The situation is more favorable in the fourth area of Likouala, a region of flooded forests in the north of the country. PMID:3542258

  6. Downregulation of Organic Anion Transporting Polypeptide (OATP) 1B1 Transport Function by Lysosomotropic Drug Chloroquine: Implication in OATP-Mediated Drug-Drug Interactions.

    PubMed

    Alam, Khondoker; Pahwa, Sonia; Wang, Xueying; Zhang, Pengyue; Ding, Kai; Abuznait, Alaa H; Li, Lang; Yue, Wei

    2016-03-01

    Organic anion transporting polypeptide (OATP) 1B1 mediates the hepatic uptake of many drugs including lipid-lowering statins. Decreased OATP1B1 transport activity is often associated with increased systemic exposure of statins and statin-induced myopathy. Antimalarial drug chloroquine (CQ) is also used for long-term treatment of rheumatoid arthritis and systemic lupus erythematosus. CQ is lysosomotropic and inhibits protein degradation in lysosomes. The current studies were designed to determine the effects of CQ on OATP1B1 protein degradation, OATP1B1-mediated transport in OATP1B1-overexpressing cell line, and statin uptake in human sandwich-cultured hepatocytes (SCH). Treatment with lysosome inhibitor CQ increased OATP1B1 total protein levels in HEK293-OATP1B1 cells and in human SCH as determined by OATP1B1 immunoblot. In HEK293-FLAG-tagged OATP1B1 stable cell line, co-immunofluorescence staining indicated that intracellular FLAG-OATP1B1 is colocalized with lysosomal associated membrane glycoprotein (LAMP)-2, a marker protein of late endosome/lysosome. Enlarged LAMP-2-positive vacuoles with FLAG-OATP1B1 protein retained inside were readily detected in CQ-treated cells, consistent with blocking lysosomal degradation of OATP1B1 by CQ. In HEK293-OATP1B1 cells, without pre-incubation, CQ concentrations up to 100 μM did not affect OATP1B1-mediated [(3)H]E217G accumulation. However, pre-incubation with CQ at clinically relevant concentration(s) significantly decreased [(3)H]E217G and [(3)H]pitavastatin accumulation in HEK293-OATP1B1 cells and [(3)H]pitavastatin accumulation in human SCH. CQ pretreatment (25 μM, 2 h) resulted in ∼1.9-fold decrease in Vmax without affecting Km of OATP1B1-mediated [(3)H]E217G transport in HEK293-OATP1B1 cells. Pretreatment with monensin and bafilomycin A1, which also have lysosome inhibition activity, significantly decreased OATP1B1-mediated transport in HEK293-OATP1B1 cells. Pharmacoepidemiologic studies using data from the U.S. Food

  7. In Vitro and Molecular Surveillance for Antimalarial Drug Resistance in Plasmodium falciparum Parasites in Western Kenya Reveals Sustained Artemisinin Sensitivity and Increased Chloroquine Sensitivity

    PubMed Central

    Komino, Franklin; Okoth, Sheila Akinyi; Goldman, Ira; Onyona, Philip; Wiegand, Ryan E.; Juma, Elizabeth; Shi, Ya Ping; Barnwell, John W.; Udhayakumar, Venkatachalam; Kariuki, Simon

    2015-01-01

    Malaria control is hindered by the evolution and spread of resistance to antimalarials, necessitating multiple changes to drug policies over time. A comprehensive antimalarial drug resistance surveillance program is vital for detecting the potential emergence of resistance to antimalarials, including current artemisinin-based combination therapies. An antimalarial drug resistance surveillance study involving 203 Plasmodium falciparum malaria-positive children was conducted in western Kenya between 2010 and 2013. Specimens from enrolled children were analyzed in vitro for sensitivity to chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ), lumefantrine, and artemisinin derivatives (artesunate and dihydroartemisinin) and for drug resistance allele polymorphisms in P. falciparum crt (Pfcrt), Pfmdr-1, and the K13 propeller domain (K13). We observed a significant increase in the proportion of samples with the Pfcrt wild-type (CVMNK) genotype, from 61.2% in 2010 to 93.0% in 2013 (P < 0.0001), and higher proportions of parasites with elevated sensitivity to CQ in vitro. The majority of isolates harbored the wild-type N allele in Pfmdr-1 codon 86 (93.5%), with only 7 (3.50%) samples with the N86Y mutant allele (the mutant nucleotide is underlined). Likewise, most isolates harbored the wild-type Pfmdr-1 D1246 allele (79.8%), with only 12 (6.38%) specimens with the D1246Y mutant allele and 26 (13.8%) with mixed alleles. All the samples had a single copy of the Pfmdr-1 gene (mean of 0.907 ± 0.141 copies). None of the sequenced parasites had mutations in K13. Our results suggest that artemisinin is likely to remain highly efficacious and that CQ sensitivity appears to be on the rise in western Kenya. PMID:26392510

  8. In Vitro and Molecular Surveillance for Antimalarial Drug Resistance in Plasmodium falciparum Parasites in Western Kenya Reveals Sustained Artemisinin Sensitivity and Increased Chloroquine Sensitivity.

    PubMed

    Lucchi, Naomi W; Komino, Franklin; Okoth, Sheila Akinyi; Goldman, Ira; Onyona, Philip; Wiegand, Ryan E; Juma, Elizabeth; Shi, Ya Ping; Barnwell, John W; Udhayakumar, Venkatachalam; Kariuki, Simon

    2015-12-01

    Malaria control is hindered by the evolution and spread of resistance to antimalarials, necessitating multiple changes to drug policies over time. A comprehensive antimalarial drug resistance surveillance program is vital for detecting the potential emergence of resistance to antimalarials, including current artemisinin-based combination therapies. An antimalarial drug resistance surveillance study involving 203 Plasmodium falciparum malaria-positive children was conducted in western Kenya between 2010 and 2013. Specimens from enrolled children were analyzed in vitro for sensitivity to chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ), lumefantrine, and artemisinin derivatives (artesunate and dihydroartemisinin) and for drug resistance allele polymorphisms in P. falciparum crt (Pfcrt), Pfmdr-1, and the K13 propeller domain (K13). We observed a significant increase in the proportion of samples with the Pfcrt wild-type (CVMNK) genotype, from 61.2% in 2010 to 93.0% in 2013 (P < 0.0001), and higher proportions of parasites with elevated sensitivity to CQ in vitro. The majority of isolates harbored the wild-type N allele in Pfmdr-1 codon 86 (93.5%), with only 7 (3.50%) samples with the N86Y mutant allele (the mutant nucleotide is underlined). Likewise, most isolates harbored the wild-type Pfmdr-1 D1246 allele (79.8%), with only 12 (6.38%) specimens with the D1246Y mutant allele and 26 (13.8%) with mixed alleles. All the samples had a single copy of the Pfmdr-1 gene (mean of 0.907 ± 0.141 copies). None of the sequenced parasites had mutations in K13. Our results suggest that artemisinin is likely to remain highly efficacious and that CQ sensitivity appears to be on the rise in western Kenya. PMID:26392510

  9. Molecular Mechanism of Renal Tubular Secretion of the Antimalarial Drug Chloroquine

    PubMed Central

    Müller, Fabian; König, Jörg; Glaeser, Hartmut; Schmidt, Ingrid; Zolk, Oliver; Fromm, Martin F.; Maas, Renke

    2011-01-01

    The antimalarial drug chloroquine is eliminated to a significant extent by renal tubular secretion. The molecular mechanism of renal chloroquine secretion remains unknown. We hypothesized that organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1), localized in the basolateral and luminal membranes of proximal tubule cells, respectively, are involved in chloroquine transport. The interaction of chloroquine with both transporters was investigated using single-transfected human embryonic kidney 293 (HEK293)-MATE1 cells in uptake experiments and single-transfected Madin-Darby canine kidney II (MDCK)-OCT2 and MDCK-MATE1 cells as well as double-transfected MDCK-OCT2-MATE1 cells grown as polarized monolayers on transwell filters. In HEK293-MATE1 cells, chloroquine competitively inhibited MATE1-mediated metformin uptake (Ki = 2.8 μM). Cellular accumulation of chloroquine was significantly lower (P < 0.001) and transcellular chloroquine transport was significantly increased (P < 0.001) in MDCK-MATE1 and MDCK-OCT2-MATE1 cells compared to vector control cells after basal addition of chloroquine (0.1 to 10 μM). In contrast, no difference in cellular accumulation or transcellular transport of chloroquine was observed between MDCK-OCT2 and vector control cells. In line with an oppositely directed proton gradient acting as a driving force for MATE1, basal-to-apical transport of chloroquine by MDCK-OCT2-MATE1 cells increased with decreasing apical pH from 7.8 to 6.0. Transcellular transport of chloroquine by MDCK-OCT2-MATE1 cells was inhibited by cimetidine, trimethoprim, and amitriptyline. Our data demonstrate that chloroquine is a substrate and potent competitive inhibitor of MATE1, whereas OCT2 seems to play no role in chloroquine uptake. Concomitantly administered MATE1 inhibitors are likely to modify the renal secretion of chloroquine. PMID:21518836

  10. The combined treatment with chloroquine and the enzymatic oxidation products of spermine overcomes multidrug resistance of melanoma M14 ADR2 cells: a new therapeutic approach.

    PubMed

    Agostinelli, Enzo; Condello, Maria; Tempera, Giampiero; Macone, Alberto; Bozzuto, Giuseppina; Ohkubo, Shinji; Calcabrini, Annarica; Arancia, Giuseppe; Molinari, Agnese

    2014-09-01

    It has been confirmed that multidrug resistant (MDR) melanoma cells (M14 ADR2) are more sensitive than their wild-type counterparts (M14 WT) to H2O2 and aldehydes, the products of bovine serum amine oxidase (BSAO)-catalyzed oxidation of spermine. The metabolites formed by BSAO and spermine are more toxic, in M14 cells, than exogenous H2O2 and acrolein, even though their concentration is lower during the initial phase of incubation due to their more gradual release than the exogenous products. Binding of BSAO to the cell membrane and release of the reaction products of spermine into the immediate vicinity of the cells, or directly into the cells, may explain the apparently paradoxical phenomenon. Both WT and MDR cells, after pre-treatment for 24 h, or longer, with the lysosomotropic compound chloroquine (CQ), show to be sensitized to subsequent exposure to BSAO/spermine enzymatic system. Evidence of ultrastructural aberrations and acridine orange release from lysosomes is presented in this study that is in favor of the permeabilization of the lysosomal membrane as the major cause of sensitization by CQ. Pre-treatment with CQ amplifies the ability of the metabolites formed from spermine by oxidative deamination to induce cell death. Melanocytes, differently from melanoma cells, were unaffected by the enzymatic system, even when preceded by CQ treatment. Since it is conceivable that combined treatment with a lysosomotropic compound and BSAO/spermine would be effective against tumour cells, it is of interest to search for such novel compounds, which might be promising for application in a therapeutic setting. PMID:24969157

  11. 4-Aminoquinoline derivatives: Synthesis, in vitro and in vivo antiplasmodial activity against chloroquine-resistant parasites.

    PubMed

    Singh, Shailja; Agarwal, Drishti; Sharma, Kumkum; Sharma, Manish; Nielsen, Morten A; Alifrangis, Michael; Singh, Ashok K; Gupta, Rinkoo D; Awasthi, Satish K

    2016-10-21

    Synthetic quinoline derivatives continue to be considered as candidates for new drug discovery if they act against CQ-resistant strains of malaria even after the widespread emergence of resistance to CQ. In this study, we explored the activities of two series of new 4-aminoquinoline derivatives and found them to be effective against Plasmodium falciparum under in vitro conditions. Further, we selected four most active derivatives 1m, 1o, 2c and 2j and evaluated their antimalarial potential against Plasmodium berghei in vivo. These 4-aminoquinolines cured BALB/c mice infected with P. berghei. The ED50 values were calculated to be 2.062, 2.231, 1.431, 1.623 and 1.18 mg/kg of body weight for each of the compounds 1m, 1o, 2c, 2j and amodiaquine, respectively. Total doses of 500 mg/kg of body weight were well received. The study suggests that these new 4-aminoquinolines should be used for structure activity relationship to find lead molecules for treating multidrug-resistant Plasmodium falciparum and Plasmodium vivax. PMID:27394399

  12. [Duodenal ulcers caused by chloroquine-proguanil association].

    PubMed

    Roux, X; Imbert, P; Rivière, F; Méchaï, F; Rapp, C

    2010-12-01

    Chloroquine-proguanil association is recommended for prophylaxis against falciparum malaria in countries with a low prevalence of chloroquine resistance. It is usually well tolerated with mild side effects consisting mainly of transient digestive discomfort and buccal manifestations (mouth sores or ulcers). The purpose of this report is to describe a case of duodenal ulcers presenting as epigastric pain with 10-kg weight-loss in a 32-year-old man taking chloroquine-proguanil for malaria prophylaxis during a stay in Haiti. No other causes of duodenal ulcers or weight-loss were found. Chloroquine-proguanil prophylaxis was discontinued and replaced by omeprazole for four weeks. Symptoms improved quickly and full recovery was observed within one month. To our knowledge, the occurrence of duodenal ulcers under chloroquine-proguanil association is quite rare, but possibly severe. Upper digestive endoscopy should be performed if a patient under chloroquine-proguanil develops abdominal pain especially in association with weight-loss. If endoscopy reveals duodenal ulcers, chloroquine-proguanil should be discontinued and replaced by another prophylactic regimen. PMID:21520638

  13. Efficacy of Artesunate-mefloquine for Chloroquine-resistant Plasmodium vivax Malaria in Malaysia: An Open-label, Randomized, Controlled Trial

    PubMed Central

    Grigg, Matthew J.; William, Timothy; Menon, Jayaram; Barber, Bridget E.; Wilkes, Christopher S.; Rajahram, Giri S.; Edstein, Michael D.; Auburn, Sarah; Price, Ric N.; Yeo, Tsin W.; Anstey, Nicholas M.

    2016-01-01

    Background. Chloroquine (CQ)-resistant Plasmodium vivax is increasingly reported throughout southeast Asia. The efficacy of CQ and alternative artemisinin combination therapies (ACTs) for vivax malaria in Malaysia is unknown. Methods. A randomized, controlled trial of CQ vs artesunate-mefloquine (AS-MQ) for uncomplicated vivax malaria was conducted in 3 district hospitals in Sabah, Malaysia. Primaquine was administered on day 28. The primary outcome was the cumulative risk of treatment failure by day 28 by Kaplan–Meier analysis. Results. From 2012 to 2014, 103 adults and children were enrolled. Treatment failure by day 28 was 61.1% (95% confidence interval [CI], 46.8–75.6) after CQ and 0% (95% CI, 0–.08) following AS-MQ (P < .001), of which 8.2% (95% CI, 2.5–9.6) were early treatment failures. All patients with treatment failure had therapeutic plasma CQ concentrations at day 7. Compared with CQ, AS-MQ was associated with faster parasite clearance (normalized clearance slope, 0.311 vs 0.127; P < .001) and fever clearance (mean, 19.0 vs 37.7 hours; P = .001) and with lower risk of anemia at day 28 (odds ratio = 3.7; 95% CI, 1.5–9.3; P = .005). Gametocytes were present at day 28 in 23.8% (10/42) of patients following CQ vs none with AS-MQ (P < .001). AS-MQ resulted in lower bed occupancy: 4037 vs 6510 days/1000 patients (incidence rate ratio 0.62; 95% CI, .60–.65; P < .001). One patient developed severe anemia not regarded as related to their AS-MQ treatment. Conclusions. High-grade CQ-resistant P. vivax is prevalent in eastern Malaysia. AS-MQ is an efficacious ACT for all malaria species. Wider CQ-efficacy surveillance is needed in vivax-endemic regions with earlier replacement with ACT when treatment failure is detected. Clinical Trials Registration. NCT01708876. PMID:27107287

  14. Experimental chloroquine retinopathy.

    PubMed

    Matsumura, M; Ohkuma, M; Tsukahara, I

    1986-01-01

    Chloroquine retinopathy was produced experimentally in the eye of the albino corydoras (one of the tropical fish) by daily administration of chloroquine (0.1 mg per os). The enucleated eyes were examined from the 14th day to 3 months after the beginning of drug administration under light and electron microscopy. The first change of retina was the appearance of membraneous cytoplasmic body (MCB) in the cytoplasm of ganglion, amacrine, bipolar and horizontal cells. MCB might be degenerated lysosome. They showed lamellar figures or crystalline lattice-like structures. Secondarily, these MCB appeared in the inner segments of photoreceptor cells. The outer segments of rod cells disappeared, and then those of cone cells. Although photoreceptor cells were diminished in number in advanced degeneration, the cells of inner nuclear layer and ganglion cells were maintained in number. The presence of MCB dose not mean death of cells. The retinal pigment epithelial cells contained MCB in its cytoplasm only in severe degenerative cases, and did not show other remarkable changes. MCB also appeared in the cytoplasm of pericytes of retinal vessels. Chloroquine is considered to damage directly photoreceptor cells most severely. PMID:3018650

  15. Delayed-onset chloroquine retinopathy.

    PubMed Central

    Ehrenfeld, M; Nesher, R; Merin, S

    1986-01-01

    Delayed-onset chloroquine retinopathy was diagnosed in a patient seven years after cessation of treatment by a total dose of 730 g of chloroquine for rheumatoid arthritis. Visual functions continued to deteriorate after the diagnosis. Periodic examinations by ophthalmoscopy and by functional tests such as EOG and visual fields should be continued in patients at risk of delayed-onset chloroquine retinopathy after discontinuance of the drug. PMID:3964626

  16. Chloroquine sensitizes biofilms of Candida albicans to antifungal azoles.

    PubMed

    Shinde, Ravikumar Bapurao; Raut, Jayant Shankar; Chauhan, Nitin Mahendra; Karuppayil, Sankunny Mohan

    2013-01-01

    Biofilms formed by Candida albicans, a human pathogen, are known to be resistant to different antifungal agents. Novel strategies to combat the biofilm associated Candida infections like multiple drug therapy are being explored. In this study, potential of chloroquine to be a partner drug in combination with four antifungal agents, namely fluconazole, voriconazole, amphotericin B, and caspofungin, was explored against biofilms of C. albicans. Activity of various concentrations of chloroquine in combination with a particular antifungal drug was analyzed in a checkerboard format. Growth of biofilm in presence of drugs was analyzed by XTT-assay, in terms of relative metabolic activity compared to that of drug free control. Results obtained by XTT-metabolic assay were confirmed by scanning electron microscopy. The interactions between chloroquine and four antifungal drugs were determined by calculating fractional inhibitory concentration indices. Azole resistance in biofilms was reverted significantly (p<0.05) in presence of 250μg/mL of chloroquine, which resulted in inhibition of biofilms at very low concentrations of antifungal drugs. No significant alteration in the sensitivity of biofilms to caspofungin and amphotericin B was evident in combination with chloroquine. This study for the first time indicates that chloroquine potentiates anti-biofilm activity of fluconazole and voriconazole. PMID:23602464

  17. Ocular Complications of Chloroquine Therapy

    PubMed Central

    Tamler, Edward

    1965-01-01

    Long-term therapy with chloroquine can lead to irreversible retinal damage and serious loss of visual acuity and visual field. Not only are the retinal changes irreversible but they may continue to progress after discontinuance of the drug. Work is proceeding on the development of electrophysiological techniques for early detection of toxic effect before significant retinal damage occurs. Another possibility for minimizing the toxic effect of chloroquine is the use of other drugs which increase the excretion of chloroquine from the body. ImagesFigure 1. PMID:14336789

  18. Role of copper transporters in platinum resistance

    PubMed Central

    Kilari, Deepak; Guancial, Elizabeth; Kim, Eric S

    2016-01-01

    Platinum (Pt)-based antitumor agents are effective in the treatment of many solid malignancies. However, their efficacy is limited by toxicity and drug resistance. Reduced intracellular Pt accumulation has been consistently shown to correlate with resistance in tumors. Proteins involved in copper homeostasis have been identified as Pt transporters. In particular, copper transporter receptor 1 (CTR1), the major copper influx transporter, has been shown to play a significant role in Pt resistance. Clinical studies demonstrated that expression of CTR1 correlated with intratumoral Pt concentration and outcomes following Pt-based therapy. Other CTRs such as CTR2, ATP7A and ATP7B, may also play a role in Pt resistance. Recent clinical studies attempting to modulate CTR1 to overcome Pt resistance may provide novel strategies. This review discusses the role of CTR1 as a potential predictive biomarker of Pt sensitivity and a therapeutic target for overcoming Pt resistance. PMID:26862494

  19. Basis of antimalarial action: non-weak base effects of chloroquine on acid vesicle pH

    SciTech Connect

    Krogstad, D.J.; Schlesinger, P.H.

    1987-03-01

    Biologically active concentrations of chloroquine increase the pH of the parasite's acid vesicles within 3-5 min. This increase in pH results from two mechanisms, one of which is markedly reduced in chloroquine-resistant parasites. Because chloroquine is a weak base, it increases vesicle pH by that mechanism in chloroquine-susceptible and resistant parasites and mammalian cells (based on its two pKs and on the delta pH between the acid vesicle and the extracellular environment). In chloroquine-susceptible parasites, but not resistant parasites or mammalian cells, chloroquine increases the pH of acid vesicles 700- to 800-fold more than can be accounted for by its properties as a weak base. The increase in acid vesicle pH caused by these non-weak base effects of nanomolar chloroquine in susceptible parasites suggests that chloroquine acts by interfering with acid vesicle functions in the parasite such as the endocytosis and proteolysis of hemoglobin, and the intracellular targeting of lysosomal enzymes. The non-weak base effects of nanomolar chloroquine on parasite vesicle pH are also responsible for its safety because these chloroquine concentrations do not affect mammalian cells.

  20. Delayed Onset Chloroquine Retinopathy Presenting 10 Years after Long-Term Usage of Chloroquine

    PubMed Central

    Kazi, Mohmmad Salman; Saurabh, Kumar; Rishi, Pukhraj; Rishi, Ekta

    2013-01-01

    Chloroquine retinopathy is a known complication of long-term use of chloroquine. This retinopathy can appear even after usage of chloroquine has stopped. The present case report describes the history and clinical features of chloroquine retinopathy developing a decade after discontinuing the drug. PMID:23580861

  1. Chloroquine psychosis: a chemical psychosis?

    PubMed

    Mohan, D; Mohandas, E; Rajat, R

    1981-11-01

    Psychotic states are mimicked by the use of many drugs including amphetamines, cannabis, lysergic acid diethylamide, psilocybin, mescaline, isoniazid, and L-dopa. A paranoid psychotic picture in a clear sensorium is characteristic of amphetamine psychosis. In developing countries, malaria among other diseases is a frequent indicator of chloroquine administration. The present communication reports a series of chloroquine-induced psychosis in a clear sensorium simulating affective illness, such as mania, mixed affective states, or depression. The psychosis disappeared after cessation of the drug, combined with or without the use of low dosage phenothiazines in excited patients. From our cases, two types of presentation of chloroquine psychosis could be seen: (1) psychic with clear sensorium, mood changes, alteration in motor activity, delusions, and hallucinations; and (2) psycho-organic with clouded sensorium, disorientation, and fleeting hallucinations. The precise nature of the mechanism of the psychosis is not clear because of the limited number of reported cases. PMID:7310924

  2. Chloroquine Has a Cytotoxic Effect on Acanthamoeba Encystation through Modulation of Autophagy

    PubMed Central

    Jha, Bijay Kumar; Jung, Hui-Jung; Seo, Incheol; Kim, Hyun Ah; Suh, Seong-Il; Suh, Min-Ho

    2014-01-01

    Encystation of Acanthamoeba castellanii is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of Acanthamoeba. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in A. castellanii. Chloroquine was able to selectively reduce cell survival during the encystation of A. castellanii. However, A. castellanii trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting Acanthamoeba. These results suggest a potential novel therapeutic application of chloroquine as an anti-Acanthamoeba drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against Acanthamoeba infection. PMID:25114131

  3. Chloroquine has a cytotoxic effect on Acanthamoeba encystation through modulation of autophagy.

    PubMed

    Jha, Bijay Kumar; Jung, Hui-Jung; Seo, Incheol; Kim, Hyun Ah; Suh, Seong-Il; Suh, Min-Ho; Baek, Won-Ki

    2014-10-01

    Encystation of Acanthamoeba castellanii is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of Acanthamoeba. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in A. castellanii. Chloroquine was able to selectively reduce cell survival during the encystation of A. castellanii. However, A. castellanii trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting Acanthamoeba. These results suggest a potential novel therapeutic application of chloroquine as an anti-Acanthamoeba drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against Acanthamoeba infection. PMID:25114131

  4. Ocular Complications of Chloroquine Therapy

    PubMed Central

    Lloyd, Lois A.; Hiltz, John W.

    1965-01-01

    Ocular complications of long-term chloroquine therapy were observed in 18 of 45 patients so treated. This therapy was used in patients with rheumatoid arthritis, lupus erythematosus, sarcoidosis, discoid lupus and other chronic “collagen disease”. Thirteen patients had reversible corneal opacifications, and seven had irreversible retinal changes, with visual loss and visual field defects. Pathological evidence of chloroquine retinopathy was obtained in one patient. Physicians are therefore warned to use this drug only after careful consideration. If it is used, repeated ocular examinations should include assessment of visual acuity, visual fields on a tangent screen and fundus examination through a dilated pupil. ImagesFig. 4Fig. 7Fig. 8 PMID:14275038

  5. Magnetic microbead transport during resistive pulse sensing

    PubMed Central

    Willmott, Geoff R.; Fisk, Matthew G.; Eldridge, James

    2013-01-01

    Tunable resistive pulse sensing (TRPS) experiments have been used to quantitatively study the motion of 1 μm superparamagnetic beads in a variable magnetic field. Closed-form theory has been developed to interpret the experiments, incorporating six particle transport mechanisms which depend on particle position in and near a conical pore. For our experiments, calculations indicate that pressure-driven flow dominates electrophoresis and magnetism by a factor of ∼100 in the narrowest part of the pore, but that magnetic force should dominate further than ∼1 mm from the membrane. As expected, the observed resistive pulse rate falls as the magnet is moved closer to the pore, while the increase in pulse duration suggests that trajectories in the half space adjacent to the pore opening are important. Aggregation was not observed, consistent with the high hydrodynamic shear near the pore constriction and the high magnetization of aggregates. The theoretical approach is also used to calculate the relative importance of transport mechanisms over a range of geometries and experimental conditions extending well beyond our own experiments. TRPS is emerging as a versatile form of resistive pulse sensing, while magnetic beads are widely used in biotechnology and sensing applications. PMID:24396540

  6. In vitro antimalarial activity and chloroquine potentiating action of two bisbenzylisoquinoline enantiomer alkaloids isolated from Strychnopsis thouarsii and Spirospermum penduliflorum.

    PubMed

    Ratsimamanga-Urverg, S; Rasoanaivo, P; Ramiaramanana, L; Milijaona, R; Rafatro, H; Verdier, F; Rakoto-Ratsimamanga, A; Le Bras, J

    1992-12-01

    The bisbenzylisoquinolines 7-O-demethyltetrandrine and limacine, respectively, isolated from Strychnopsis thouarsii Baill. and Spirospermum penduliflorum Thou. were evaluated for their intrinsic antimalarial activity in vitro and chloroquine potentiating action against the chloroquine-resistant Plasmodium falciparum FCM 29 originating from Cameroon. They both showed significant antiplasmodial potency in vitro with very similar IC50 values of respectively, 740 nM and 789 nM (IC50 = 214 nM for chloroquine used as standard drug), which demonstrated that the stereochemistry of the C-1 and C-1' configuration likely plays a role in the chloroquine potentiating effect of these drugs. If confirmed in vivo, these results may account for the traditional use of the two plants as antimalarials and adjuvant to chloroquine in Madagascan folklore remedies. PMID:1484894

  7. Piercing tool, Transportation Accident Resistant Container (TARC)

    SciTech Connect

    Lari, P.

    1994-08-01

    Transportation Accident Resistant Containers (TARC)s are used for enhanced safety during movement of nuclear weapons. Its design features a tough stainless steel outer skin, redwood for impact mitigation and fire protection and a rugged aluminum inner container. Redwood absorbs impact energy by crushing, similar to the way foam crushes in other containers. Redwood also functions to insulate the weapon from heat and fire. When a TARC is involved in a fire, the redwood will slowly burn forming a good insulating char. The redwood can continue to smolder once the fire is out. To ensure the smolder is extinguished, water can be directed into any accident caused hole in the skin. If no hole exists, it may be necessary to create one. This document discusses tool selection, testing, and a simple but effective method of creating an access hole in the outer skin large enough to apply fire fighting techniques.

  8. Determination of chloroquine and monodesethylchloroquine in hair.

    PubMed

    Viala, A; Deturmeny, E; Aubert, C; Estadieu, M; Durand, A; Cano, J P; Delmont, J

    1983-10-01

    Using thin-layer and gas chromatography and mass spectrometry, chloroquine and its major metabolite (monodesethylchloroquine) were identified in hair samples of numerous patients who received this antimalarial drug for several months. In two patients the amounts of chloroquine were, respectively, 310 and 145 mg/kg hair and those of the monodesethylchloroquine 23 and 11 mg/kg. The respective proportions (93 and 7%) are the same in the two subjects. The chloroquine percentage was near those in the spleen or stomach wall after poisoning. Other metabolites in hair are being identified. Hair analysis may provide a good toxicologic and forensic science complement to the blood, urine, and tissues. It may be useful for the control of chloroquine therapy. PMID:6631371

  9. Temporal and Seasonal Changes of Genetic Polymorphisms Associated with Altered Drug Susceptibility to Chloroquine, Lumefantrine, and Quinine in Guinea-Bissau between 2003 and 2012

    PubMed Central

    Kofoed, Poul-Erik; Rombo, Lars; Rodrigues, Amabelia; Ursing, Johan

    2014-01-01

    In 2008, artemether-lumefantrine was introduced in Guinea-Bissau, West Africa, but quinine has also been commonly prescribed for the treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine have been described. P. falciparum chloroquine resistance transporter (pfcrt) K76T, pfmdr1 gene copy numbers, pfmdr1 polymorphisms N86Y and Y184F, and pfmdr1 sequences 1034 to 1246 were determined using PCR-based methods. Blood samples came from virtually all (n = 1,806) children <15 years of age who had uncomplicated P. falciparum monoinfection and presented at a health center in suburban Bissau (from 2003 to 2012). The pfcrt K76T and pfmdr1 N86Y frequencies were stable, and seasonal changes were not seen from 2003 to 2007. Since 2007, the mean annual frequencies increased (P < 0.001) for pfcrt 76T (24% to 57%), pfmdr1 N86 (72% to 83%), and pfcrt 76 + pfmdr1 86 TN (10% to 27%), and pfcrt 76T accumulated during the high transmission season (P = 0.001). The pfmdr1 86 + 184 NF frequency increased from 39% to 66% (from 2003 to 2011; P = 0.004). One sample had two pfmdr1 gene copies. pfcrt 76T was associated with a lower parasite density (P < 0.001). Following the discontinuation of an effective chloroquine regimen, probably highly artemether-lumefantrine-susceptible P. falciparum (with pfcrt 76T) accumulated, possibly due to suboptimal use of quinine and despite a fitness cost linked to pfcrt 76T. (The studies reported here were registered at ClinicalTrials.gov under registration no. NCT00137514 [PSB-2001-chl-amo], NCT00137566 [PSB-2004-paracetamol], NCT00426439 [PSB-2006-coartem], NCT01157689 [AL-eff 2010], and NCT01704508 [Eurartesim 2012].) PMID:25421474

  10. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine in Guinea-Bissau between 2003 and 2012.

    PubMed

    Jovel, Irina Tatiana; Kofoed, Poul-Erik; Rombo, Lars; Rodrigues, Amabelia; Ursing, Johan

    2015-02-01

    In 2008, artemether-lumefantrine was introduced in Guinea-Bissau, West Africa, but quinine has also been commonly prescribed for the treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine have been described. P. falciparum chloroquine resistance transporter (pfcrt) K76T, pfmdr1 gene copy numbers, pfmdr1 polymorphisms N86Y and Y184F, and pfmdr1 sequences 1034 to 1246 were determined using PCR-based methods. Blood samples came from virtually all (n=1,806) children<15 years of age who had uncomplicated P. falciparum monoinfection and presented at a health center in suburban Bissau (from 2003 to 2012). The pfcrt K76T and pfmdr1 N86Y frequencies were stable, and seasonal changes were not seen from 2003 to 2007. Since 2007, the mean annual frequencies increased (P<0.001) for pfcrt 76T (24% to 57%), pfmdr1 N86 (72% to 83%), and pfcrt 76+pfmdr1 86 TN (10% to 27%), and pfcrt 76T accumulated during the high transmission season (P=0.001). The pfmdr1 86+184 NF frequency increased from 39% to 66% (from 2003 to 2011; P=0.004). One sample had two pfmdr1 gene copies. pfcrt 76T was associated with a lower parasite density (P<0.001). Following the discontinuation of an effective chloroquine regimen, probably highly artemether-lumefantrine-susceptible P. falciparum (with pfcrt 76T) accumulated, possibly due to suboptimal use of quinine and despite a fitness cost linked to pfcrt 76T. (The studies reported here were registered at ClinicalTrials.gov under registration no. NCT00137514 [PSB-2001-chl-amo], NCT00137566 [PSB-2004-paracetamol], NCT00426439 [PSB-2006-coartem], NCT01157689 [AL-eff 2010], and NCT01704508 [Eurartesim 2012].). PMID:25421474

  11. Therapeutic efficacy of chloroquine and sulfadoxine/pyrimethamine against Plasmodium falciparum infection in Somalia.

    PubMed Central

    Warsame, M.; Abdillahi, A.; Duale, O. Nur; Ismail, A. Nur; Hassan, A. M.; Mohamed, A.; Warsame, A.

    2002-01-01

    OBJECTIVE: To assess the efficacy of chloroquine and sulfadoxine/pyrimethamine in the treatment of uncomplicated Plasmodium falciparum infections in Somalia. METHODS: Patients with clinical malaria in Merca, an area of high transmission of the disease, were treated with the standard regimens of chloroquine (25 mg/kg) or sulfadoxine/pyrimethamine (25 mg sulfadoxine and 1.25 mg pyrimethamine per kg). Similar patients in Gabiley, an area of low transmission, received the standard regimen of chloroquine. The clinical and parasitological responses were monitored for 14 days. FINDINGS: Chloroquine treatment resulted in clinical failure in 33% (n = 60) and 51% (n = 49) of the patients in Merca and Gabiley respectively. There were corresponding parasitological failures of 77% RII/RIII and 35% RII/RIII. Patients who experienced clinical failure had significantly higher initial parasitaemia than those in whom there was an adequate clinical response, both in Merca (t = 2.2; P t = 2.8; P n = 50) of the patients achieved an adequate clinical response despite a parasitological failure rate of 76% RII/RIII. CONCLUSION: Chloroquine should no longer be considered adequate for treating clinical falciparum malaria in vulnerable groups in the areas studied. Doubts about the therapeutic life of sulfadoxine/pyrimethamine in relation to malaria are raised by the high levels of resistance in the Merca area and underline the need to identify suitable alternatives. PMID:12378287

  12. Implications of Glutathione Levels in the Plasmodium berghei Response to Chloroquine and Artemisinin.

    PubMed

    Vega-Rodríguez, Joel; Pastrana-Mena, Rebecca; Crespo-Lladó, Keila N; Ortiz, José G; Ferrer-Rodríguez, Iván; Serrano, Adelfa E

    2015-01-01

    Malaria is one of the most devastating parasitic diseases worldwide. Plasmodium drug resistance remains a major challenge to malaria control and has led to the re-emergence of the disease. Chloroquine (CQ) and artemisinin (ART) are thought to exert their anti-malarial activity inducing cytotoxicity in the parasite by blocking heme degradation (for CQ) and increasing oxidative stress. Besides the contribution of the CQ resistance transporter (PfCRT) and the multidrug resistant gene (pfmdr), CQ resistance has also been associated with increased parasite glutathione (GSH) levels. ART resistance was recently shown to be associated with mutations in the K13-propeller protein. To analyze the role of GSH levels in CQ and ART resistance, we generated transgenic Plasmodium berghei parasites either deficient in or overexpressing the gamma-glutamylcysteine synthetase gene (pbggcs) encoding the rate-limiting enzyme in GSH biosynthesis. These lines produce either lower (pbggcs-ko) or higher (pbggcs-oe) levels of GSH than wild type parasites. In addition, GSH levels were determined in P. berghei parasites resistant to CQ and mefloquine (MQ). Increased GSH levels were detected in both, CQ and MQ resistant parasites, when compared to the parental sensitive clone. Sensitivity to CQ and ART remained unaltered in both pgggcs-ko and pbggcs-oe parasites when tested in a 4 days drug suppressive assay. However, recrudescence assays after the parasites have been exposed to a sub-lethal dose of ART showed that parasites with low levels of GSH are more sensitive to ART treatment. These results suggest that GSH levels influence Plasmodium berghei response to ART treatment. PMID:26010448

  13. Implications of Glutathione Levels in the Plasmodium berghei Response to Chloroquine and Artemisinin

    PubMed Central

    Vega-Rodríguez, Joel; Pastrana-Mena, Rebecca; Crespo-Lladó, Keila N.; Ortiz, José G.; Ferrer-Rodríguez, Iván; Serrano, Adelfa E.

    2015-01-01

    Malaria is one of the most devastating parasitic diseases worldwide. Plasmodium drug resistance remains a major challenge to malaria control and has led to the re-emergence of the disease. Chloroquine (CQ) and artemisinin (ART) are thought to exert their anti-malarial activity inducing cytotoxicity in the parasite by blocking heme degradation (for CQ) and increasing oxidative stress. Besides the contribution of the CQ resistance transporter (PfCRT) and the multidrug resistant gene (pfmdr), CQ resistance has also been associated with increased parasite glutathione (GSH) levels. ART resistance was recently shown to be associated with mutations in the K13-propeller protein. To analyze the role of GSH levels in CQ and ART resistance, we generated transgenic Plasmodium berghei parasites either deficient in or overexpressing the gamma-glutamylcysteine synthetase gene (pbggcs) encoding the rate-limiting enzyme in GSH biosynthesis. These lines produce either lower (pbggcs-ko) or higher (pbggcs-oe) levels of GSH than wild type parasites. In addition, GSH levels were determined in P. berghei parasites resistant to CQ and mefloquine (MQ). Increased GSH levels were detected in both, CQ and MQ resistant parasites, when compared to the parental sensitive clone. Sensitivity to CQ and ART remained unaltered in both pgggcs-ko and pbggcs-oe parasites when tested in a 4 days drug suppressive assay. However, recrudescence assays after the parasites have been exposed to a sub-lethal dose of ART showed that parasites with low levels of GSH are more sensitive to ART treatment. These results suggest that GSH levels influence Plasmodium berghei response to ART treatment. PMID:26010448

  14. Chloroquine cardiomyopathy: beyond ocular adverse effects

    PubMed Central

    Lopez-Ruiz, Nilson; Uribe, Carlos Esteban

    2014-01-01

    A 36-year-old woman who had received long-term treatment with chloroquine for systemic lupus erythematosus developed a third degree atrioventricular block and required a permanent pacemaker. Notably, left ventricular thickening and mild systolic dysfunction were noticed on echocardiography as well as on cardiac MRI. As there was no clear explanation for myocardial findings, the patient underwent an endomyocardial biopsy that demonstrated vacuolar degeneration of myocytes on light microscopy and curvilinear bodies on electron microscopy, both findings consistent with chloroquine toxicity. The drug was withheld and treatment with candesartan and carvedilol was prescribed. At 2-year follow-up, the patient remained asymptomatic and left ventricular systolic function had improved. Physicians who prescribe antimalarial drugs for rheumatic diseases should be aware of the potentially life-threatening effects of chloroquine on the heart. PMID:25225192

  15. Azithromycin plus chloroquine: combination therapy for protection against malaria and sexually transmitted infections in pregnancy

    PubMed Central

    Chico, R Matthew; Chandramohan, Daniel

    2011-01-01

    Introduction: The first-line therapy for the intermittent preventive treatment of malaria in pregnancy (IPTp) is sulphadoxine-pyrimethamine (SP). There is an urgent need to identify safe, well-tolerated and efficacious alternatives to SP due to widespread Plasmodium falciparum resistance. Combination therapy using azithromycin and chloroquine is one possibility that has demonstrated adequate parasitological response > 95% in clinical trials of non-pregnant adults in sub-Saharan Africa and where IPTp is a government policy in 33 countries. Areas covered: Key safety, tolerability and efficacy data are presented for azithromycin and chloroquine, alone and/or in combination, when used to prevent and/or treat P. falciparum, P. vivax, and several curable sexually transmitted and reproductive tract infections (STI/RTI). Pharmacokinetic evidence from pregnant women is also summarized for both compounds. Expert opinion: The azithromycin-chloroquine regimen that has demonstrated consistent efficacy in non-pregnant adults has been a 3-day course containing daily doses of 1 g of azithromycin and 600 mg base of chloroquine. The pharmacokinetic evidence of these compounds individually suggests that dose adjustments may not be necessary when used in combination for treatment efficacy against P. falciparum, P. vivax, as well as several curable STI/ RTI among pregnant women, although clinical confirmation will be necessary. Mass trachoma-treatment campaigns have shown that azithromycin selects for macrolide resistance in the pneumococcus, which reverses following the completion of therapy. Most importantly, no evidence to date suggests that azithromycin induces pneumococcal resistance to penicillin. PMID:21736423

  16. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Embutramide, chloroquine, and lidocaine solution... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications. Each milliliter (mL) of solution contains 135 milligrams (mg) embutramide; 45 mg chloroquine phosphate,...

  17. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Embutramide, chloroquine, and lidocaine solution... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications. Each milliliter (mL) of solution contains 135 milligrams (mg) embutramide; 45 mg chloroquine phosphate,...

  18. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Embutramide, chloroquine, and lidocaine solution... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications. Each milliliter (mL) of solution contains 135 milligrams (mg) embutramide; 45 mg chloroquine phosphate,...

  19. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Embutramide, chloroquine, and lidocaine solution... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications. Each milliliter (mL) of solution contains 135 milligrams (mg) embutramide; 45 mg chloroquine phosphate,...

  20. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Embutramide, chloroquine, and lidocaine solution... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications. Each milliliter (mL) of solution contains 135 milligrams (mg) embutramide; 45 mg chloroquine phosphate,...

  1. In silico attempt for adduct agent(s) against malaria: Combination of chloroquine with alkaloids of Adhatoda vasica.

    PubMed

    Swain, Shasank S; Sahu, Mahesh C; Padhy, Rabindra N

    2015-10-01

    With the aim of controlling drug resistant Plasmodium falciparum, a computational attempt of designing novel adduct antimalarial drugs through the molecular docking method of combining chloroquine with five alkaloids, individually is presented. These alkaloids were obtained from the medicinal plant, Adhatoda vasica. From the obtained individual docking values of important derivatives of quinine and chloroquine, as well as, individual alkaloids and adduct agents of chloroquine with Adhatoda alkaloids as ligands, it was discernible that the 'adduct agent-1 with chloroquine and adhatodine' combination had the minimum energy of interaction, as the docking score value of -11.144 kcal/mol against the target protein, triosephosphate isomerase (TIM), the key enzyme of glycolytic pathway. Drug resistance of P. falciparum is due to a mutation in the polypeptide of TIM. Moratorium of mutant TIM would disrupt the metabolism during the control of the drug resistant P. falciparum. This in silico work helped to locate the 'adduct agent-1 with chloroquine and adhatodine', which could be taken up by pharmacology for further development of this compound as a new drug against drug resistant Plasmodium. PMID:26142781

  2. Interruption of malaria transmission by chloroquinized salt in Guyana

    PubMed Central

    Giglioli, George; Rutten, Frans J.; Ramjattan, S.

    1967-01-01

    Malaria and its local vector, Anopheles darlingi, were eradicated from the coastlands and near interior of Guyana by DDT house-spraying in 1945-51. In the remote interior, where 10% of the population live, only partial control could be achieved, owing to the semi-silvatic habits of A. darlingi and the considerable movement of the sparse population; low malaria endemicity persisted in these areas with occasional localized outbreaks. In the south-west the problem was further complicated by the presence of malaria across the frontier. During the years 1961-65, the use of chloroquinized salt was made compulsory over an area of some 109 000 km2, covering a population of 48 500. Satisfactory results were obtained over 84% of this area within 6 months of the start of the campaign; only four cases of malaria were seen in four years. In the south-west, however, an initially favourable trend was reversed in 1962 with the introduction of a chloroquine-resistant strain of Plasmodium falciparum from Brazil. The situation was brought under control by house-spraying with DDT and interruption of transmission is expected. PMID:4864651

  3. Effect of wall roughness on fluid transport resistance in nanopores

    NASA Astrophysics Data System (ADS)

    Xu, Baoxing; Li, Yibing; Park, Taehyo; Chen, Xi

    2011-10-01

    Using non-equilibrium molecular dynamics simulations, we investigate the effect of wall roughness on the transport resistance of water molecules inside modified carbon nanotubes. The effective shear stress, which characterizes the strong interaction between liquid molecules and solid wall, is a quantity that dominates the nanofluidic transport resistance. Both the effective shear stress and nominal viscosity arise with the increase of the amplitude or the decrease of the wavelength of roughness. The effect of roughness is also relatively more prominent in smaller nanotubes. The molecular mechanism is elucidated through the study of the radial density profile, hydrogen bonding, and velocity field of the confined water molecules.

  4. Synthesis, Characterization and in vitro Antimalarial and Antitumor Activity of New Ruthenium(II) Complexes of Chloroquine

    PubMed Central

    Rajapakse, Chandima S. K.; Martínez, Alberto; Naoulou, Becky; Jarzecki, Andrzej A.; Suárez, Liliana; Deregnaucourt, Christiane; Sinou, Véronique; Schrével, Joseph; Musi, Elgilda; Ambrosini, Grazia; Schwartz, Gary K.; Sánchez-Delgado, Roberto A.

    2009-01-01

    The new RuII chloroquine complexes [Ru(η6-arene)(CQ)Cl2] (CQ = chloroquine; arene = p-cymene 1, benzene 2), [Ru(η6-p-cymene)(CQ)(H2O)2][BF4]2 (3), [Ru(η6-p-cymene)(CQ)(en)][PF6]2 (en = ethylenediamine) (4), and [Ru(η6-p-cymene)(η6-CQDP)][BF4]2 (5, CQDP = chloroquine diphosphate) have been synthesized and characterized by use of a combination of NMR and FTIR spectroscopy with DFT calculations. Each complex is formed as a single coordination isomer: in compounds 1–4 chloroquine binds to ruthenium in the η1-N mode through the quinoline nitrogen atom whereas in complex 5 an unprecedented η6 bonding through the carbocyclic ring is observed. Compounds 1, 2, 3, and 5 are active against CQ-resistant (Dd2, K1 and W2) and CQ-sensitive (FcB1, PFB, F32 and 3D7) malaria parasites (Plasmodium falciparum); importantly, the potency of these complexes against resistant parasites is consistently higher than that of the standard drug chloroquine diphosphate. Complexes 1 and 5 also inhibit the growth of colon cancer cells, independently of the p53 status and of liposarcoma tumor cell lines with the latter showing increased sensitivity, especially to complex 1 (IC50 8 µM); this is significant because this type of tumor does not respond to currently employed chemotherapies. PMID:19119867

  5. Chloroquine and hydroxychloroquine for cancer therapy

    PubMed Central

    Manic, Gwenola; Obrist, Florine; Kroemer, Guido; Vitale, Ilio; Galluzzi, Lorenzo

    2014-01-01

    Macroautophagy (herein referred to as autophagy) is a highly conserved mechanism for the lysosomal degradation of cytoplasmic components. Autophagy is critical for the maintenance of intracellular homeostasis, both in baseline conditions and in the context of adaptive responses to stress. In line with this notion, defects in the autophagic machinery have been etiologically associated with various human disorders including infectious, inflammatory and neoplastic conditions. Once tumors are established, however, autophagy sustains the survival of malignant cells, hence representing an appealing target for the design of novel anticancer regimens. Accordingly, inhibitors of autophagy including chloroquine and hydroxychloroquine have been shown to mediate substantial antineoplastic effects in preclinical models, especially when combined with chemo- or radiotherapeutic interventions. The pharmacological profile of chloroquine and hydroxychloroquine, however, appear to involve mechanisms other than autophagy inhibition. Here, we discuss the dual role of autophagy in oncogenesis and tumor progression, and summarize the results or design of clinical studies recently completed or initiated to evaluate the therapeutic activity of chloroquine derivatives in cancer patients. PMID:27308318

  6. Pentacycloundecylamines and conjugates thereof as chemosensitizers and reversed chloroquine agents.

    PubMed

    Joubert, Jacques; Fortuin, Elton E; Taylor, Dale; Smith, Peter J; Malan, Sarel F

    2014-12-01

    The control of malaria has been complicated by increased resistance of the malaria parasite to existing antimalarials such as chloroquine (CQ). Herein, we report the ability of NGP1-01, the prototype pentacycloundecylamine (PCU), to reverse CQ resistance (>50%) and act as a chemosensitizer. Based on this finding we set out to synthesize a small series of novel agents comprising of a PCU moiety as the reversal agent conjugated to a CQ-like aminoquinoline (AM) molecule and evaluate the potential of these PCU-AM derivatives as reversed CQ agents. PCU-AM derivatives 1-3 showed anti-plasmodial IC50 values in the ranges of 3.74-17.6 nM and 27.6-253.5 nM against CQ-sensitive (D10) and CQ-resistant strains (Dd2) of Plasmodium falciparum, respectively. Compound 1 presented with the best antiplasmodial activity at low nM concentrations against both strains and was found to be 5 fold more active against the resistant strain than CQ. Compound 1 can be considered as a lead compound to develop reversed CQ agents with improved pharmacodynamic and pharmacokinetic properties. PMID:25451997

  7. Membrane transporters and drought resistance - a complex issue.

    PubMed

    Jarzyniak, Karolina M; Jasiński, Michał

    2014-01-01

    Land plants have evolved complex adaptation strategies to survive changes in water status in the environment. Understanding the molecular nature of such adaptive changes allows the development of rapid innovations to improve crop performance. Plant membrane transport systems play a significant role when adjusting to water scarcity. Here we put proteins participating in transmembrane allocations of various molecules in the context of stomatal, cuticular, and root responses, representing a part of the drought resistance strategy. Their role in the transport of signaling molecules, ions or osmolytes is summarized and the challenge of the forthcoming research, resulting from the recent discoveries, is highlighted. PMID:25538721

  8. Membrane transporters and drought resistance – a complex issue

    PubMed Central

    Jarzyniak, Karolina M.; Jasiński, Michał

    2014-01-01

    Land plants have evolved complex adaptation strategies to survive changes in water status in the environment. Understanding the molecular nature of such adaptive changes allows the development of rapid innovations to improve crop performance. Plant membrane transport systems play a significant role when adjusting to water scarcity. Here we put proteins participating in transmembrane allocations of various molecules in the context of stomatal, cuticular, and root responses, representing a part of the drought resistance strategy. Their role in the transport of signaling molecules, ions or osmolytes is summarized and the challenge of the forthcoming research, resulting from the recent discoveries, is highlighted. PMID:25538721

  9. Keratopathy with low dose chloroquine therapy.

    PubMed

    Cullen, A P; Chou, B R

    1986-05-01

    Antimalarial drugs (4-aminoguinolines) are often used as non-steroidal anti-inflammatories and remission inducers in the treatment of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In this paper we report on ocular signs of aminoquinolinic toxicity among 39 patients, 31 with RA and 8 with SLE. These patients received either chloroquine 250 mg q.h.s. or hydroxychloroquine 200 mg b.i.d. No maculopathy was detected, however 75% of the patients showed various degrees of keratopathy ranging from epithelial haze to dense "whorl" deposits. No correlation was found between severity of the keratopathy and the estimated total amount of aminoquinoline administered. PMID:3711574

  10. Azithromycin-chloroquine and the intermittent preventive treatment of malaria in pregnancy

    PubMed Central

    Chico, R Matthew; Pittrof, Rudiger; Greenwood, Brian; Chandramohan, Daniel

    2008-01-01

    In the high malaria-transmission settings of sub-Saharan Africa, malaria in pregnancy is an important cause of maternal, perinatal and neonatal morbidity. Intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) reduces the incidence of low birth-weight, pre-term delivery, intrauterine growth-retardation and maternal anaemia. However, the public health benefits of IPTp are declining due to SP resistance. The combination of azithromycin and chloroquine is a potential alternative to SP for IPTp. This review summarizes key in vitro and in vivo evidence of azithromycin and chloroquine activity against Plasmodium falciparum and Plasmodium vivax, as well as the anticipated secondary benefits that may result from their combined use in IPTp, including the cure and prevention of many sexually transmitted diseases. Drug costs and the necessity for external financing are discussed along with a range of issues related to drug resistance and surveillance. Several scientific and programmatic questions of interest to policymakers and programme managers are also presented that would need to be addressed before azithromycin-chloroquine could be adopted for use in IPTp. PMID:19087267

  11. Multidrug resistance ABC transporter structure predictions by homology modeling approaches.

    PubMed

    Honorat, Mylène; Falson, Pierre; Terreux, Raphael; Di Pietro, Attilio; Dumontet, Charles; Payen, Léa

    2011-03-01

    Human multidrug resistance ABC transporters are ubiquitous membrane proteins responsible for the efflux of multiple, endogenous or exogenous, compounds out of the cells, and therefore they are involved in multi-drug resistance phenotype (MDR). They thus deeply impact the pharmacokinetic parameters and toxicity properties of drugs. A great pressure to develop inhibitors of these pumps is carried out, by either ligand-based drug design or (more ideally) structure-based drug design. In that goal, many biochemical studies have been carried out to characterize their transport functions, and many efforts have been spent to get high-resolution structures. Currently, beside the 3D-structures of bacterial ABC transporters Sav1866 and MsbA, only the mouse ABCB1 complete structure has been published at high-resolution, illustrating the tremendous difficulty in getting such information, taking into account that the human genome accounts for 48 ABC transporters encoding genes. Homology modeling is consequently a reasonable approach to overcome this obstacle. The present review describes, in the first part, the different approaches which have been published to set up human ABC pump 3D-homology models allowing the localization of binding sites for drug candidates, and the identification of critical residues therein. In a second part, the review proposes a more accurate strategy and practical keys to use such biological tools for initiating structure-based drug design. PMID:21470105

  12. Role of xenobiotic efflux transporters in resistance to vincristine.

    PubMed

    Huang, Rong S; Murry, Daryl J; Foster, David R

    2008-02-01

    This study characterized interactions between efflux transporters (P-glycoprotein (MDR1) and multidrug resistance associated proteins (MRPs1-3)) and vincristine (VCR), using cell lines with differential transporter expression, and studied effects of P-glycoprotein inhibition on VCR transport and toxicity. Caco2 (express MDR1, MRPs 1-3), LS174T (express MDR1, MRPs 1, 3), and A549 (express MRPs 1-3) cells were used. To study VCR transport (effective permeability, P(eff)), VCR (1-500 nM) was added to the donor chambers of permeable supports containing Caco2 monolayers, and receiving chamber concentrations were measured. Cytotoxicity experiments were conducted with escalating concentrations of VCR in all cell lines. To determine the contribution of MDR1, experiments were also conducted with LY335979, a specific MDR1 inhibitor. VCR P(eff) was 2 x 10(-6)cm/s in Caco2 cells. LY335979 increased P(eff) in a dose dependent manner (up to 7-fold with 1 microM LY335979) in Caco2 cells. Caco2 and LS174T cell viability decreased significantly when co-incubated with both VCR and LY335979 (1 microM) (P<0.05), however this was not observed in A549 cells. In summary, MDR1 plays an important role in VCR efflux; MDR1 inhibition increased VCR P(eff) in Caco2 cells, and increased VCR cytotoxicity in Caco2 and LS174T cells (both express MDR1), but not A549 cells (minimal MDR1 expression). Inhibition of MDR1 may be a viable strategy to overcome VCR resistance in tumors expressing MDR1, however the presence of other efflux transporters should also be considered, as this will influence the success of such strategies. PMID:17583464

  13. Battling the malaria iceberg with chloroquine in India

    PubMed Central

    Sharma, Vinod P

    2007-01-01

    The National Vector Borne Disease Control Programme (NVBDCP) of the Ministry of Health, Government of India is reporting about 2 million parasite positive cases each year, although case incidence is 30-fold or more under-estimated. Forty five to fifty percent of Plasmodium infections are caused by Plasmodium falciparum, the killer parasite. Anti-malaria drug policy (2007) of the NVBDC recommends chloroquine (CQ) as the first line of drug for the treatment of all malarias. In a Primary Health Centre (PHC) reporting 10% or more cases of CQ resistance in P. falciparum, ACT blister pack is recommended and, so far, the policy has been adopted in 261 PHCs of 71 districts. The NVBDCP still depends on CQ to combat malaria and, as a result, P. falciparum has taken deep roots in malaria-endemic regions, causing unacceptable levels of morbidity and mortality. This policy was a subject of criticism in recent Nature and Lancet articles questioning the World Bank's decision to supply CQ to the NVBDCP. Continuation of an outdated drug in the treatment of P. falciparum is counterproductive in fighting drug resistant malaria and in the containment of P. falciparum. Switchover to Artemisinin-based Combination Therapy (ACT) in the treatment of all P. falciparum cases, ban on artemisinin monotherapy and effective vector control (treated nets/efficient insecticide spraying) would be a rational approach to malaria control in India. PMID:17683630

  14. A Study of Transport Airplane Crash-Resistant Fuel Systems

    NASA Technical Reports Server (NTRS)

    Jones, Lisa (Technical Monitor); Robertson, S. H.; Johnson, N. B.; Hall, D. S.; Rimson, I. J.

    2002-01-01

    This report presents the results of a study, funded by the Federal Aviation Administration (FAA), of transport airplane crash-resistant fuel system (CRFS). The report covers the historical studies related to aircraft crash fires and fuel containment concepts undertaken by the FAA, NASA, and the U.S. Army, which ultimately led to the current state of the art in CRFS technology. It describes the basic research, testing, field investigations and production efforts which have led to the highly successful military CRFS, which has saved many lives and reduced costs of accidents. Current CRFS technology used in transport category airplanes is defined and compared to the available state-of-the-art technology. The report provides information to the FAA and other government organizations which can help them plan their efforts to improve the state of crash fire protection in the transport airplane fleet. The report provides guidance to designers looking for information about CRFS design problems, analysis tools to use for product improvement, and a summary of current and proposed regulations for transport category airplane fuel systems.

  15. In utero exposure to chloroquine alters sexual development in the male fetal rat

    SciTech Connect

    Clewell, Rebecca A. Pluta, Linda; Thomas, Russell S.; Andersen, Melvin E.

    2009-06-15

    Chloroquine (CQ), a drug that has been used extensively for the prevention and treatment of malaria, is currently considered safe for use during pregnancy. However, CQ has been shown to disrupt steroid homeostasis in adult rats and similar compounds, such as quinacrine, inhibit steroid production in the Leydig cell in vitro. To explore the effect of in utero CQ exposure on fetal male sexual development, pregnant Sprague-Dawley rats were given a daily dose of either water or chloroquine diphosphate from GD 16-18 by oral gavage. Chloroquine was administered as 200 mg/kg CQ base on GD 16, followed by two maintenance doses of 100 mg/kg CQ base on GD 16 and 18. Three days of CQ treatment resulted in reduced maternal and fetal weight on GD 19 and increased necrosis and steatosis in the maternal liver. Fetal livers also displayed mild lipid accumulation. Maternal serum progesterone was increased after CQ administration. Fetal testes testosterone, however, was significantly decreased. Examination of the fetal testes revealed significant alterations in vascularization and seminiferous tubule development after short-term CQ treatment. Anogenital distance was not altered. Microarray and RT-PCR showed down-regulation of several genes associated with cholesterol transport and steroid synthesis in the fetal testes. This study indicates that CQ inhibits testosterone synthesis and normal testis development in the rat fetus at human relevant doses.

  16. ABC transporters as multidrug resistance mechanisms and the development of chemosensitizers for their reversal

    PubMed Central

    Choi, Cheol-Hee

    2005-01-01

    One of the major problems related with anticancer chemotherapy is resistance against anticancer drugs. The ATP-binding cassette (ABC) transporters are a family of transporter proteins that are responsible for drug resistance and a low bioavailability of drugs by pumping a variety of drugs out cells at the expense of ATP hydrolysis. One strategy for reversal of the resistance of tumor cells expressing ABC transporters is combined use of anticancer drugs with chemosensitizers. In this review, the physiological functions and structures of ABC transporters, and the development of chemosensitizers are described focusing on well-known proteins including P-glycoprotein, multidrug resistance associated protein, and breast cancer resistance protein. PMID:16202168

  17. Transport of tylosin and tylosin-resistance genes in subsurface drainage water from manured fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal agriculture appears to contribute to the spread of antibiotic resistance genes, but few studies have quantified gene transport in agricultural fields. The transport of tylosin, tylosin-resistance genes (erm B, F, A) and tylosin-resistant Enterococcus were measured in tile drainage water from ...

  18. Ruthenium(II) arene complexes with chelating chloroquine analogue ligands: Synthesis, characterization and in vitro antimalarial activity†

    PubMed Central

    Glans, Lotta; Ehnbom, Andreas; de Kock, Carmen; Martínez, Alberto; Estrada, Jesús; Smith, Peter J.; Haukka, Matti; Sánchez-Delgado, Roberto A.; Nordlander, Ebbe

    2012-01-01

    Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η6-cym)(L1)Cl]Cl (1, cym = p-cymene, L1 = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η6-cym)(L2)Cl]Cl (2, L2 = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η6-cym)(L3)Cl] (3, L3 = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1–3 and ligands L1, L2 and L3, as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L4), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated. While 1 and 2 are less active than the corresponding ligands, 3 exhibits high antimalarial activity. The chloroquine analogue L2 also shows good activity against both the choloroquine sensitive and the chloroquine resistant strains. Heme aggregation inhibition activity (HAIA) at an aqueous buffer/n-octanol interface (HAIR50) and lipophilicity (D, as measured by water/n-octanol distribution coefficients) have been measured for all ligands and metal complexes. A direct correlation between the D and HAIR50 properties cannot be made because of the relative structural diversity of the complexes, but it may be noted that these properties are enhanced upon complexation of the inactive ligand L3 to ruthenium, to give a metal complex (3) with promising antimalarial activity. PMID:22249579

  19. Retinal toxicity of chloroquine hydrochloride administered by intraperitoneal injection.

    PubMed

    Gaynes, Bruce Ira; Torczynski, Elise; Varro, Zoltan; Grostern, Richard; Perlman, Jay

    2008-10-01

    Chloroquine is quinolone derivative known to exert dose-related retinal toxicity, albeit in a variable manner. It is thought that variability in the presentation of chloroquine retinopathy may be the result of perturbations in drug bioavailability subsequent to oral ingestion. In order to better understand the ramifications of bioavailability on the development of retinal injury subsequent to chloroquine use, this study investigated the relationship between retinal injury and chloroquine administration via intraperitoneal rather than oral administration. Four-week-old C57/6J mice underwent daily intraperitoneal injection of 10 mg kg(-1) chloroquine hydrochloride for a total of 62 days. Following treatment, tissue was fixed in preparation for analysis by light and transmission electron microscopy. Treated animals demonstrated marked abnormality of the outer retinal layers described as complete loss of the outer plexiform layer as well as photoreceptors and photoreceptor nuclei. The retinal pigmented epithelium demonstrated focal atrophy, loss of nuclei and pigment irregularity. Findings in the inner retina were notable for the loss of Müller cells and the presence of membranous cytoplasmic bodies. Retinae of control animals were entirely normal. In contrast to previous studies in the murine model examining chloroquine retinopathy subsequent to oral administration, this study suggests that intraperitoneal chloroquine administration facilitates retinal toxicity, presumably due to heightened drug absorption and bioavailability. It is posited that an increased rate of drug accumulation within the retina leads to an enhanced lysosomotrophic drug effect due to inability of the lysosome to compensate for chloroquine-induced elevation in pH through re-acidification of the intra-lysosomal content. PMID:18484088

  20. Hair analysis of an unusual case of Chloroquine intoxication.

    PubMed

    Imran, Muhammad; Ashiq, Muhammad Zar; Shafi, Humera; Usman, Hafiz Faisal; Wattoo, Sardar Ali; Sarwar, Muhammad; Tahir, Muhammad Ashraf

    2016-03-01

    A dead body of middle aged man was exhumed from 6.5 month earth-grave. Autopsy findings were non-specific as the body was completely putrefied. Deceased's scalp hair and kidney was sent for toxicological analysis. Hair sample (50mg) was incubated with 1M NaOH (2 ml). Chloroquine was detected in hair and kidney during basic drug screen performed on GC/MS. For confirmation and quantitation, chloroquine was extracted using Hypersep verify CX SPE cartridges while mass detector was operated in SIM mode using the ions of m/z 245.0, 290.1, 319.0 for chloroquine while ions of m/z 260 and 455 were monitored for nalorphine (internal standard). Chloroquine was present in high concentration in hair (211 ng/mg) as well as in kidney (37.3mg/kg). Moreover, chloroquine was not detected in the wash solvents, suggesting ingestion of the drug rather than an external contamination of hair. These findings strongly suggested the acute exposure of higher doses of chloroquine to the deceased before death. PMID:26980246

  1. P-glycoproteins and other multidrug resistance transporters in the pharmacology of anthelmintics: Prospects for reversing transport-dependent anthelmintic resistance

    PubMed Central

    Lespine, Anne; Ménez, Cécile; Bourguinat, Catherine; Prichard, Roger K.

    2011-01-01

    Parasitic helminths cause significant disease in animals and humans. In the absence of alternative treatments, anthelmintics remain the principal agents for their control. Resistance extends to the most important class of anthelmintics, the macrocyclic lactone endectocides (MLs), such as ivermectin, and presents serious problems for the livestock industries and threatens to severely limit current parasite control strategies in humans. Understanding drug resistance is important for optimizing and monitoring control, and reducing further selection for resistance. Multidrug resistance (MDR) ABC transporters have been implicated in ML resistance and contribute to resistance to a number of other anthelmintics. MDR transporters, such as P-glycoproteins, are essential for many cellular processes that require the transport of substrates across cell membranes. Being overexpressed in response to chemotherapy in tumour cells and to ML-based treatment in nematodes, they lead to therapy failure by decreasing drug concentration at the target. Several anthelmintics are inhibitors of these efflux pumps and appropriate combinations can result in higher treatment efficacy against parasites and reversal of resistance. However, this needs to be balanced against possible increased toxicity to the host, or the components of the combination selecting on the same genes involved in the resistance. Increased efficacy could result from modifying anthelmintic pharmacokinetics in the host or by blocking parasite transporters involved in resistance. Combination of anthelmintics can be beneficial for delaying selection for resistance. However, it should be based on knowledge of resistance mechanisms and not simply on mode of action classes, and is best started before resistance has been selected to any member of the combination. Increasing knowledge of the MDR transporters involved in anthelmintic resistance in helminths will play an important role in allowing for the identification of markers

  2. P type porous silicon resistivity and carrier transport

    SciTech Connect

    Ménard, S.; Fèvre, A.; Billoué, J.; Gautier, G.

    2015-09-14

    The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P{sub %}) was found to be the major contributor to the PS resistivity (ρ{sub PS}). ρ{sub PS} increases exponentially with P{sub %}. Values of ρ{sub PS} as high as 1 × 10{sup 9} Ω cm at room temperature were obtained once P{sub %} exceeds 60%. ρ{sub PS} was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρ{sub PS}. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P{sub %} lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P{sub %} overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices.

  3. Trametinib modulates cancer multidrug resistance by targeting ABCB1 transporter

    PubMed Central

    Qiu, Jian-Ge; Zhang, Yao-Jun; Li, Yong; Zhao, Jin-Ming; Zhang, Wen-Ji; Jiang, Qi-Wei; Mei, Xiao-Long; Xue, You-Qiu; Qin, Wu-Ming; Yang, Yang; Zheng, Di-Wei; Chen, Yao; Wei, Meng-Ning; Shi, Zhi

    2015-01-01

    Overexpression of adenine triphosphate (ATP)-binding cassette (ABC) transporters is one of the main reasons of multidrug resistance (MDR) in cancer cells. Trametinib, a novel specific small-molecule mitogen-activated extracellular signal-regulated kinase (MEK) inhibitor, is currently used for the treatment of melanoma in clinic. In this study, we investigated the effect of trametinib on MDR mediated by ABC transporters. Trametinib significantly potentiated the effects of two ABCB1 substrates vincristine and doxorubicin on inhibition of growth, arrest of cell cycle and induction of apoptosis in cancer cells overexpressed ABCB1, but not ABCC1 and ABCG2. Furthermore, trametinib did not alter the sensitivity of non-ABCB1 substrate cisplatin. Mechanistically, trametinib potently blocked the drug-efflux activity of ABCB1 to increase the intracellular accumulation of rhodamine 123 and doxorubicin and stimulates the ATPase of ABCB1 without alteration of the expression of ABCB1. Importantly, trametinib remarkably enhanced the effect of vincristine against the xenografts of ABCB1-overexpressing cancer cells in nude mice. The predicted binding mode showed the hydrophobic interactions of trametinib within the large drug binding cavity of ABCB1. Consequently, our findings may have important implications for use of trametinib in combination therapy for cancer treatment. PMID:25915534

  4. Purification of a Multidrug Resistance Transporter for Crystallization Studies

    PubMed Central

    Alegre, Kamela O.; Law, Christopher J.

    2015-01-01

    Crystallization of integral membrane proteins is a challenging field and much effort has been invested in optimizing the overexpression and purification steps needed to obtain milligram amounts of pure, stable, monodisperse protein sample for crystallography studies. Our current work involves the structural and functional characterization of the Escherichia coli multidrug resistance transporter MdtM, a member of the major facilitator superfamily (MFS). Here we present a protocol for isolation of MdtM to increase yields of recombinant protein to the milligram quantities necessary for pursuit of structural studies using X-ray crystallography. Purification of MdtM was enhanced by introduction of an elongated His-tag, followed by identification and subsequent removal of chaperonin contamination. For crystallization trials of MdtM, detergent screening using size exclusion chromatography determined that decylmaltoside (DM) was the shortest-chain detergent that maintained the protein in a stable, monodispersed state. Crystallization trials of MdtM performed using the hanging-drop diffusion method with commercially available crystallization screens yielded 3D protein crystals under several different conditions. We contend that the purification protocol described here may be employed for production of high-quality protein of other multidrug efflux members of the MFS, a ubiquitous, physiologically and clinically important class of membrane transporters. PMID:27025617

  5. Purification of a Multidrug Resistance Transporter for Crystallization Studies.

    PubMed

    Alegre, Kamela O; Law, Christopher J

    2015-01-01

    Crystallization of integral membrane proteins is a challenging field and much effort has been invested in optimizing the overexpression and purification steps needed to obtain milligram amounts of pure, stable, monodisperse protein sample for crystallography studies. Our current work involves the structural and functional characterization of the Escherichia coli multidrug resistance transporter MdtM, a member of the major facilitator superfamily (MFS). Here we present a protocol for isolation of MdtM to increase yields of recombinant protein to the milligram quantities necessary for pursuit of structural studies using X-ray crystallography. Purification of MdtM was enhanced by introduction of an elongated His-tag, followed by identification and subsequent removal of chaperonin contamination. For crystallization trials of MdtM, detergent screening using size exclusion chromatography determined that decylmaltoside (DM) was the shortest-chain detergent that maintained the protein in a stable, monodispersed state. Crystallization trials of MdtM performed using the hanging-drop diffusion method with commercially available crystallization screens yielded 3D protein crystals under several different conditions. We contend that the purification protocol described here may be employed for production of high-quality protein of other multidrug efflux members of the MFS, a ubiquitous, physiologically and clinically important class of membrane transporters. PMID:27025617

  6. Streptococcus mutans: Fructose Transport, Xylitol Resistance, and Virulence

    PubMed Central

    Tanzer, J.M.; Thompson, A.; Wen, Z.T.; Burne, R.A.

    2008-01-01

    Streptococcus mutans, the primary etiological agent of human dental caries, possesses at least two fructose phosphotransferase systems (PTSs), encoded by fruI and fruCD. fruI is also responsible for xylitol transport. We hypothesized that fructose and xylitol transport systems do not affect virulence. Thus, colonization and cariogenicity of fruI− and fruCD− single and double mutants, their WT (UA159), and xylitol resistance (Xr) of S. mutans were studied in rats fed a high-sucrose diet. A sucrose phosphorylase (gtfA−) mutant and a reference strain (NCTC-10449S) were additional controls. Recoveries of fruI mutant from the teeth were decreased, unlike those for the other strains. The fruCD mutation was associated with a slight loss of cariogenicity on enamel, whereas mutation of fruI was associated with a loss of cariogenicity in dentin. These results also suggest why xylitol inhibition of caries is paradoxically associated with spontaneous emergence of so-called Xr S. mutans in habitual human xylitol users. PMID:16567561

  7. Pharmacokinetics of Chloroquine and Monodesethylchloroquine in Pregnancy▿

    PubMed Central

    Karunajeewa, Harin A.; Salman, Sam; Mueller, Ivo; Baiwog, Francisca; Gomorrai, Servina; Law, Irwin; Page-Sharp, Madhu; Rogerson, Stephen; Siba, Peter; Ilett, Kenneth F.; Davis, Timothy M. E.

    2010-01-01

    In order to determine the pharmacokinetic disposition of chloroquine (CQ) and its active metabolite, desethylchloroquine (DECQ), when administered as intermittent presumptive treatment in pregnancy (IPTp) for malaria, 30 Papua New Guinean women in the second or third trimester of pregnancy and 30 age-matched nonpregnant women were administered three daily doses of 450 mg CQ (8.5 mg/kg of body weight/day) in addition to a single dose of sulfadoxine-pyrimethamine. For all women, blood was taken at baseline; at 1, 2, 4, 6, 12, 18, 24, 30, 48, and 72 h posttreatment; and at 7, 10, 14, 28, and 42 days posttreatment. Plasma was subsequently assayed for CQ and DECQ by high-performance liquid chromatography, and population pharmacokinetic modeling was performed. Pregnant subjects had significantly lower area under the plasma concentration-time curve for both CQ (35,750 versus 47,892 μg·h/liter, P < 0.001) and DECQ (23,073 versus 41,584 μg·h/liter, P < 0.001), reflecting significant differences in elimination half-lives and in volumes of distribution and clearances relative to bioavailability. Reduced plasma concentrations of both CQ and DECQ could compromise both curative efficacy and posttreatment prophylactic properties in pregnant patients. Higher IPTp CQ doses may be desirable but could increase the risk of adverse hemodynamic effects. PMID:20086162

  8. Synthesis and Antiplasmodial Activity of Novel Chloroquine Analogues with Bulky Basic Side Chains.

    PubMed

    Tasso, Bruno; Novelli, Federica; Tonelli, Michele; Barteselli, Anna; Basilico, Nicoletta; Parapini, Silvia; Taramelli, Donatella; Sparatore, Anna; Sparatore, Fabio

    2015-09-01

    Chloroquine is commonly used in the treatment and prevention of malaria, but Plasmodium falciparum, the main species responsible for malaria-related deaths, has developed resistance against this drug. Twenty-seven novel chloroquine (CQ) analogues characterized by a side chain terminated with a bulky basic head group, i.e., octahydro-2H-quinolizine and 1,2,3,4,5,6-hexahydro-1,5-methano-8H-pyrido[1,2-a][1,5]diazocin-8-one, were synthesized and tested for activity against D-10 (CQ-susceptible) and W-2 (CQ-resistant) strains of P. falciparum. Most compounds were found to be active against both strains with nanomolar or sub-micromolar IC50 values. Eleven compounds were found to be 2.7- to 13.4-fold more potent than CQ against the W-2 strain; among them, four cytisine derivatives appear to be of particular interest, as they combine high potency with low cytotoxicity against two human cell lines (HMEC-1 and HepG2) along with easier synthetic accessibility. Replacement of the 4-NH group with a sulfur bridge maintained antiplasmodial activity at a lower level, but produced an improvement in the resistance factor. These compounds warrant further investigation as potential drugs for use in the fight against malaria. PMID:26213237

  9. [Chloroquine and hydroxychloroquine: side effect profile of important therapeutic drugs].

    PubMed

    Ochsendorf, F R; Runne, U

    1991-03-01

    Precise knowledge of the undesirable effects of chloroquine and hydroxychloroquine allows better exploitation of their therapeutic effects. Retinopathy can be avoided by observing a maximum daily dosage of 3.5-4 mg/kg ideal body weight for chloroquine and 6-6.5 mg/kg for hydroxychloroquine. In this way, both can be used for long-term therapy. The pharmacokinetics of chloroquine (storage in deep compartments with long plasma half-life) means that it can cumulate, especially with higher dosages and in the presence of renal or hepatic insufficiency. A high plasma concentration reinforces the side-effects without reinforcing the therapeutic effects. Besides subjective symptoms (e.g. anorexia, diarrhoea, nausea), the following undesirable reactions are significant. On the skin exanthema, hyperpigmentation and photodynamic reactions can develop. The hair can become white in blonde and red-haired men. In the eye, chloroquine deposits in the cornea and disturbances of accommodation can occur, besides retinopathy. Neuromyopathy and central nervous system disturbances (e.g. psychosis) are rare, as is impairment of auditory function or blood cells. During pregnancy there is a risk of potential fetal damage (hearing loss, abortion). An acute overdose is extremely dangerous: the lethal dose is 1 g for children and 4 g for adults. As death occurs rapidly, chloroquine has to be stored where it is absolutely inaccessible to children. PMID:2055762

  10. In vivo response of Plasmodium falciparum to chloroquine in pregnant and non-pregnant women in Siaya District, Kenya*

    PubMed Central

    Steketee, R. W.; Brandling-Bennett, A. D.; Kaseje, D. C. O.; Schwartz, I. K.; Churchill, F. C.

    1987-01-01

    Chemoprophylaxis using chloroquine (CQ) in suppressive doses has been recommended to protect pregnant women in malarious areas from the adverse effects of malaria during pregnancy. In a malaria-endemic area of western Kenya with CQ-resistant Plasmodium falciparum, we determined the prevalence and density of falciparum infection in gravid and nulligravid women and compared the in-vivo parasite response to CQ using two regimens: 25 mg/kg body weight (CQ25) divided over a period of three days (for high-density parasitaemias) and 5 mg/kg body weight (CQ5) weekly for 4 weeks (for low-density parasitaemias). P. falciparum infections were present in 102 (42%) of 244 pregnant women. A greater proportion of primigravidae were parasitaemic (68%) than nulligravidae (50%, P=0.02) or multigravidae (33%, P <10-6). Primigravidae showed a higher geometric mean parasite density. In the CQ25 treatment group, failure to clear parasites by day 7 was more common in primigravidae than nulligravidae (P=0.008) or multigravidae (P=0.15). In the CQ5 treatment group, primigravidae were more likely to show increasing parasite density than nulligravidae or multigravidae. In this area of Kenya, virtually all women in their first pregnancy are exposed to malaria and are at greatest risk for malaria infection; compared with other women, they show higher parasite densities and are least likely to respond to chloroquine treatment in areas of chloroquine resistance. Malaria control strategies might be targeted to this group of women, but we are pessimistic about the efficacy of weekly CQ5 where there is chloroquine resistance. PMID:3325186

  11. Ecotoxicological evaluation of the antimalarial drug chloroquine.

    PubMed

    Zurita, Jorge L; Jos, Angeles; del Peso, Ana; Salguero, Manuel; López-Artíguez, Miguel; Repetto, Guillermo

    2005-10-15

    There is limited information available about the potential environmental effects of chloroquine (CQ), a widely used antimalarial agent and a promising inexpensive drug in the management of HIV disease. The acute effects of CQ were studied using four ecotoxicological model systems. The most sensitive bioindicator was the immobilization of the cladoceran Daphnia magna, with an EC50 of 12 microM CQ at 72 h and a non-observed adverse effect level of 2.5 microM CQ, followed very closely by the decrease of the uptake of neutral red and the reduction of the lysosomal function in the fish cell line PLHC-1 derived from the top minnow Poeciliopsis lucida, probably due to the selective accumulation of the drug into the lysosomes. There was significant cellular stress as indicated by the increases on metallothionein and glucose-6P dehydrogenase levels after 24 h of exposure and succinate dehydrogenase activity mainly after 48 h. No changes were observed for ethoxyresorufin-O-deethylase (EROD) activity. The least sensitive model was the inhibition of bioluminescence in the bacterium Vibrio fischeri. An increase of more than five-fold in the toxicity from 24 to 72 h of exposure was observed for the inhibition of the growth in the alga Chlorella vulgaris and the content of total protein and MTS tetrazolium salt metabolization in PLHC-1 cells. At the morphological level, the most evident alterations in PLHC-1 cultures were hydropic degeneration from 25 microM CQ after 24h of exposure and the presence of many cells with pyknotic nuclei, condensed cytoplasm and apoptosis with concentrations higher than 50 microM CQ after 48 h of exposure. In conclusion, CQ should be classified as harmful to aquatic organisms. PMID:16153718

  12. Validation of a chloroquine-induced cell death mechanism for clinical use against malaria

    PubMed Central

    Ch'ng, J-H; Lee, Y-Q; Gun, S Y; Chia, W-N; Chang, Z-W; Wong, L-K; Batty, K T; Russell, B; Nosten, F; Renia, L; Tan, K S-W

    2014-01-01

    An alternative antimalarial pathway of an ‘outdated' drug, chloroquine (CQ), may facilitate its return to the shrinking list of effective antimalarials. Conventionally, CQ is believed to interfere with hemozoin formation at nanomolar concentrations, but resistant parasites are able to efflux this drug from the digestive vacuole (DV). However, we show that the DV membrane of both resistant and sensitive laboratory and field parasites is compromised after exposure to micromolar concentrations of CQ, leading to an extrusion of DV proteases. Furthermore, only a short period of exposure is required to compromise the viability of late-stage parasites. To study the feasibility of this strategy, mice malaria models were used to demonstrate that high doses of CQ also triggered DV permeabilization in vivo and reduced reinvasion efficiency. We suggest that a time-release oral formulation of CQ may sustain elevated blood CQ levels sufficiently to clear even CQ-resistant parasites. PMID:24967967

  13. Chloroquine and sulphadoxine-pyrimethamine sensitivity of Plasmodium falciparum parasites in a Brazilian endemic area

    PubMed Central

    Gama, Bianca Ervatti; de Oliveira, Natália K Almeida; Zalis, Mariano G; de Souza, José Maria; Santos, Fátima; Daniel-Ribeiro, Cláudio Tadeu; Ferreira-da-Cruz, Maria de Fátima

    2009-01-01

    Background The goal of the present study was the characterization of Plasmodium falciparum genes associated to malaria drug resistance (pfcrt, pfdhfr and pfdhps), in samples from two Brazilian localities. Methods Parasites from 65 P. falciparum samples were genotyped using nested-PCR and direct DNA sequencing. Results Six resistant sulphadoxine-pyrimethamine (SP) pfdhfr genotypes and one haplotype associated to SP sensitivity were detected. For pfcrt gene, SVMNT chloroquine (CQ)-resistant genotype was detected as well as the CVMNK CQ-sensitive haplotype in the same sample from Paragominas, that showed a SP-sensitive genotype. Conclusion This study is the first to document the sensitivity of P. falciparum parasites to CQ and SP in Brazilian field samples. The importance of these findings is discussed. PMID:19602248

  14. Chloroquine: Ophthalmological Safety, and Clinical Assessment in Rheumatoid Arthritis

    PubMed Central

    Percival, S. P. B.; Meanock, I.

    1968-01-01

    272 patients on long-term chloroquine therapy were assessed with respect to ocular toxicity and clinical benefit. A simple scheme for rendering patients ophthalmologically safe is presented, employing the recording of central fields to red targets. Under this it was possible to diagnose a state of premaculopathy, which was reversible on stopping treatment. The incidence of premaculopathy was 41% in 143 patients who otherwise displayed no abnormality of the fundus oculi and who had received a mean total dose of 410 g. of chloroquine phosphate or the hydroxychloroquine sulphate equivalent. Under this joint ophthalmological and rheumatological supervision it was considered that the minor side-effects that may be caused by chloroquine are outweighed by its therapeutic value. ImagesFig. 3 PMID:4875645

  15. In Vivo Confocal Microscopy in Chloroquine-Induced Keratopathy

    PubMed Central

    Paladini, Iacopo; Menchini, Ugo; Mencucci, Rita

    2013-01-01

    In vivo confocal microscopy is becoming a mandatory examination to study corneal abnormalities such as drug deposits in systemic disease. A female diagnosed with fibromyalgia on systemic chloroquine for 9 months presented for an ophthalmic examination. Confocal microscopy was performed using the Confoscan 4 (Nidek Co. Ltd., Gamagori, Japan) and multiple highly reflective deposits in the epithelial basal cells were found, that were consistent with choloquine. Deposits were also present in the wing cell layer. In the anterior stroma these deposits were rare. Atypically shaped and branched nerves were also present in the anterior stroma. Corneal deposits of chloroquine can be evaluated by confocal microscopy. Confocal microscopy provides information on corneal metabolism and physiology. Chloroquine keratopathy can affect the anterior stroma in addition to the epithelium. PMID:23580857

  16. Autophagy and Transporter-Based Multi-Drug Resistance

    PubMed Central

    Kumar, Priyank; Zhang, Dong-Mei; Degenhardt, Kurt; Chen, Zhe-Sheng

    2012-01-01

    All the therapeutic strategies for treating cancers aim at killing the cancer cells via apoptosis (programmed cell death type I). Defective apoptosis endow tumor cells with survival. The cell can respond to such defects with autophagy. Autophagy is a cellular process by which cytoplasmic material is either degraded to maintain homeostasis or recycled for energy and nutrients in starvation. A plethora of evidence has shown that the role of autophagy in tumors is complex. A lot of effort is needed to underline the functional status of autophagy in tumor progression and treatment, and elucidate how to tweak autophagy to treat cancer. Furthermore, during the treatment of cancer, the limitation for the cure rate and survival is the phenomenon of multi drug resistance (MDR). The development of MDR is an intricate process that could be regulated by drug transporters, enzymes, anti-apoptotic genes or DNA repair mechanisms. Reports have shown that autophagy has a dual role in MDR. Furthermore, it has been reported that activation of a death pathway may overcome MDR, thus pointing the importance of other death pathways to regulate tumor cell progression and growth. Therefore, in this review we will discuss the role of autophagy in MDR tumors and a possible link amongst these phenomena. PMID:24710490

  17. Clinical efficacy of chloroquine followed by primaquine for Plasmodium vivax treatment in Azerbaijan.

    PubMed

    Valibayov, Abbas; Abdullayev, Farman; Mammadov, Suleyman; Gasimov, Elkhan; Sabatinelli, Guido; Kondrachine, Anatoli V; Ringwald, Pascal

    2003-09-01

    Efficacy of chloroquine followed by primaquine has been monitored in 153 patients in seven districts of Azerbaijan. Chloroquine is fully effective over the first 14 days and the combination of chloroquine and primaquine is 100% effective over 28 days. PMID:12943984

  18. ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells

    SciTech Connect

    Horio, M.; Gottesman, M.M.; Pastan, I. )

    1988-05-01

    Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate ({sup 3}H)vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent K{sub m} of 38 {mu}M for ATP and of {approx} 2 {mu}M for vinblastine. The nonhydrolyzable analog adenosine 5{prime}-({beta},{gamma}-imido)triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, and ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine > actinomycin D > daunomycin > colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process.

  19. Electro-Oculograms in the Early Diagnosis of Chloroquine Retinopathy

    PubMed Central

    Weinreb, Marvin S.

    1967-01-01

    Funduscopy, electro-oculography and electroretinography are all valuable in early detection of chloroquine retinopathy, which is reversible if detected early. Simplified instrumentation for electro-oculography was utilized in testing 12 normal controls, one patient with diabetic retinopathy and 15 patients with potential or actual cases of chloroquine retinopathy. Normal controls, and all but one of the patients without clinical evidence of retinopathy, had electro-oculographic ratios above 180. All patients having evidence of retinopathy had ratios below 180. ImagesFigure 1.Figure 2. PMID:6039185

  20. Comparison of artemether and chloroquine for severe malaria in Gambian children.

    PubMed

    White, N J; Waller, D; Crawley, J; Nosten, F; Chapman, D; Brewster, D; Greenwood, B M

    1992-02-01

    Artemether is an oil-soluble methyl ether of artemesinin (qinghaosu). It has been studied extensively in China, where it has been shown to be rapidly effective in severe falciparum malaria. Nearly all the patients studied previously were adults. We have investigated the efficacy of artemether in children with moderate or severe falciparum malaria. In the preliminary study of moderately severe malaria, 30 Gambian children were randomised in pairs to receive either intramuscular artemether (4 mg/kg loading dose followed by 2 mg/kg daily) or intramuscular chloroquine ('Nivaquine') 3.5 mg base/kg every 6 h. Both drugs were well tolerated and rapidly effective. The times to parasite clearance were significantly shorter in the artemether recipients (mean 36.7 [SD 11.3] vs 48.4 [16.8] h, p less than 0.05). 43 children with severe malaria were then randomised to receive intramuscular treatment with the same regimens of artemether (n = 21) or chloroquine (n = 22) as used in the preliminary study. 8 children (19%) died. There were no significant differences between the two groups in the clinical, haematological, biochemical, or parasitological measures of therapeutic response in survivors and there was no evidence of local or systemic toxicity. Despite similar parasite counts on admission, clearance times overall were longer in severe malaria than in moderate malaria. Artemether is a well tolerated and rapidly effective parenteral treatment for severe malaria in children, and would be especially valuable in areas with chloroquine-resistant P falciparum. PMID:1346408

  1. Effect of grapefruit juice on plasma chloroquine kinetics in mice.

    PubMed

    Ali, B H; Al-Qarawi, A; Mousa, H M

    2002-08-01

    1. It is known that grapefruit juice (GFJ) may interact with drugs concomitantly administered by inhibiting first-pass metabolism during the intestinal absorption phase. However, its interaction with chloroquine has not been studied previously. 2. Grapefruit juice (4 mL/kg) was given orally to mice 1 h prior to oral administration of chloroquine (100 mg/kg) and the concentration of the latter drug was measured fluorometrically in the plasma 0, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 12, 18 and 24 h after its administration. 3. The mean (+/-SEM) of area under the curve values after administration of water +/- control) and GFJ were 5.34 +/- 0.38 and 7.01 +/- 0.66 mg.h/L, respectively. The corresponding mean C(max) values were 763.4 +/- 39.1 and 859.2 +/- 45.2 mg/L and the corresponding T(max) values (median) were 2.65 and 2.95 h. 4. The results suggest that GFJ coingestion increased the plasma concentration of chloroquine and altered some kinetic parameters of chloroquine. The clinical significance of this interaction in patients with malaria needs to be investigated. PMID:12100003

  2. Chloride anion transporters inhibit growth of methicillin-resistant Staphylococcus aureus (MRSA) in vitro.

    PubMed

    Share, Andrew I; Patel, Khushali; Nativi, Cristina; Cho, Eun J; Francesconi, Oscar; Busschaert, Nathalie; Gale, Philip A; Roelens, Stefano; Sessler, Jonathan L

    2016-06-18

    A series of aminopyrrolic receptors were tested as anion transporters using POPC liposome model membranes. Many were found to be effective Cl(-) transporters and to inhibit clinical strains of Staphylococcus aureus growth in vitro. The best transporters proved effective against the methicillin-resistant Staphylococcus aureus (MRSA) strains, Mu50 and HP1173. Tris-thiourea tren-based chloride transporters were also shown to inhibit the growth of S. aureus in vitro. PMID:27223254

  3. Effect of chloroquine on feline infectious peritonitis virus infection in vitro and in vivo.

    PubMed

    Takano, Tomomi; Katoh, Yasuichiroh; Doki, Tomoyoshi; Hohdatsu, Tsutomu

    2013-08-01

    Feline infectious peritonitis (FIP) is a feline coronavirus-induced fatal disease in domestic and wild cats. Several studies have investigated potential treatments for FIP. However, there have been no reports on agents that have exhibited a therapeutic effect. Recently, chloroquine has been reported to antiviral effect. We investigated whether chloroquine can be used to treat FIP in vitro and in vivo. It was demonstrated that chloroquine has inhibitory effect against the replication of FIPV and anti-inflammatory effect in vitro. In vivo study using cats with experimentally induced FIP, the clinical score of chloroquine-treatment groups were better than in chloroquine-untreated group. However, alanine aminotransferase levels increased in the chloroquine-treated groups. It will be necessary to further investigate the possibility of FIP treatment with a combination of chloroquine and other agents. PMID:23648708

  4. Impact of Chloroquine on Viral Load in Breast Milk

    PubMed Central

    Semrau, Katherine; Kuhn, Louise; Kasonde, Prisca; Sinkala, Moses; Kankasa, Chipepo; Shutes, Erin; Vwalika, Cheswa; Ghosh, Mrinal; Aldrovandi, Grace; Thea, Donald M.

    2006-01-01

    Summary The anti-malarial agent chloroquine has activity against HIV. We compared the effect of chloroquine (n = 18) to an anti-malarial agent without known anti-HIV-activity, sulfadoxine-pyrimethamine (n = 12), on breast milk HIV RNA levels among HIV-infected breastfeeding women in Zambia. After adjusting for CD4 count and plasma viral load, chloroquine was associated with a trend towards lower levels of HIV RNA in breast milk compared with sulfadoxine-pyrimethamine (P 0.05). Higher breastmilk viral load was also observed among women receiving presumptive treatment = for symptomatic malaria compared with asymptomatic controls and among controls reporting fever in the prior week. Further research is needed to determine the potential role of chloroquine in prevention of HIV transmission through breastfeeding. Impacte de la chloroquine sur la charge virale dans le lait maternelle La chloroquine, agent antimalarique, a une activité contre le VIH. Nous avons comparé l’effet de la chloroquine à celui d’un autre agent antimalarique, la sulfadoxine-pyrimethamine, dont l’activité sur le VIH n’est pas connue, en mesurant les taux d’ARN de VIH dans le lait maternel de femmes allaitantes infectées par le VIH en Zambie. Après ajustement pour les taux de CD4 et la charge virale dans le plasma, la chloroquine comparée à la sulfadoxine pyrimethamine était associée à une tendance vers des teneurs plus bas en ARN de VIH dans le lait maternel (P = 0,05). Des charges virales plus élevées dans le lait maternel étaient aussi observées chez des femmes recevant un traitement présomptif pour des symptômes de malaria par rapport aux contrôles asymptomatiques et par rapport à des contrôles rapportant de la fièvre durant la première semaine. Des études supplémentaires sont nécessaires pour déterminer le rôle potentiel de la chloroquine dans la prévention de la transmission du VIH par l’allaitement maternel. mots clésVIH, malaria, allaitement maternel

  5. Chloroquine-induced scratching is mediated by NO/cGMP pathway in mice.

    PubMed

    Foroutan, Arash; Haddadi, Nazgol Sadat; Ostadhadi, Sattar; Sistany, Narges; Dehpour, Ahmad Reza

    2015-07-01

    Chloroquine (CQ), a 4-aminoquinoline drug, has long been used in the treatment and prevention of malaria. However its side effect generalized pruritus contributes to treatment failures, and consequently results in the development of chloroquine resistant strains of Plasmodium falciparum. It was proposed that the administration of CQ correlated with increase in nitric oxide (NO) production. Nitric oxide is involved in some pruritic disorders such as atopic dermatitis, psoriasis and scratching behavior evoked by pruritogens like substance P. Therefore, the aim of this study was to investigate the involvement of NO/cGMP pathway in CQ-induced scratching in mice. Scratching behaviors were recorded by a camera after intradermal (ID) injection of CQ in the shaved rostral back of the mice. The results obtained show that CQ elicited scratching in a dose-dependent manner with a peak effective dose of 400μg/site. Injection of non-specific NOS inhibitor, N-nitro-l-arginine methyl ester or neuronal NOS selective inhibitor and 7-nitroindazole, reduced CQ-induced scratching significantly. On the other hand, administration of aminoguanidine as inducible NOS inhibitor has no inhibitory effect on this behavior. Also, injection of l-arginine as a precursor of NO significantly increased this response. Conversely, accumulation of cGMP by sildenafil as a selective phosphodiesterase type 5 inhibitor, potentiated the scratching behavior by CQ. This study therefore shows that CQ-induced scratching behavior is mediated by the NO/cGMP pathway. PMID:25957523

  6. Detecting chloroquine retinopathy: electro-oculogram versus colour vision

    PubMed Central

    Neubauer, A S; Samari-Kermani, K; Schaller, U; Welge-Lüβen, U; Rudolph, G; Berninger, T

    2003-01-01

    Aim: To investigate the relative sensitivity and specificity of two tests of retinal function (the electro-oculogram (EOG) and a computerised colour vision test) in screening for ocular toxicity caused by chloroquine and hydroxychloroquine. Methods: 93 patients with rheumatic diseases receiving long term chloroquine and hydroxychloroquine therapy were followed for an average of 2.6 years. Clinical examination, an EOG, and a quantitative test of colour vision were carried out every 6 months. Results: Mild fundus changes were observed in 38 patients. Four patients developed typical bull’s eye maculopathy, three of whom had received 250, 365, and 550 g total dose of chloroquine, and one 1500 g of hydroxychloroquine. Statistical analysis of all patients showed that for those with no fundus changes or stippled pigmentation a number showed elevation of tritan threshold, so that if macular stippling is a sign of mild retinopathy the test on tritan changes has a 64% sensitivity and 63% specificity for an upper threshold value of 7%. All four patients with bull’s eye lesions showed a marked disturbance of tritan colour vision, with a threshold of 14.8%, a sensitivity of 75%, and a specificity of 94%. For protan colour vision a threshold of 10% gives 75% sensitivity and 91% specificity. By contrast, neither an absolute nor a relative EOG reduction was a valid criterion for early or late chloroquine retinopathy. In advanced retinopathy an Arden coefficient (AQ) <180% yields 50% sensitivity and 54% specificity. When AQ <160% is the threshold, sensitivity does not increase but specificity rises to 82%. Occurrence of marked corneal deposits on clinical examination yields 50% sensitivity and 90% specificity in this situation. Conclusion: Screening for chloroquine retinopathy can be improved by using a sensitive colour test. Disturbance of the tritan axis appears to occur first. A normal test result on computerised colour testing virtually excludes any retinopathy by

  7. Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin.

    PubMed

    Beseli, Aydin; Amnuaykanjanasin, Alongkorn; Herrero, Sonia; Thomas, Elizabeth; Daub, Margaret E

    2015-11-01

    The goal of this work is to characterize membrane transporter genes in Cercospora fungi required for autoresistance to the photoactivated, active-oxygen-generating toxin cercosporin they produce for infection of host plants. Previous studies implicated a role for diverse membrane transporters in cercosporin resistance. In this study, transporters identified in a subtractive cDNA library between a Cercospora nicotianae wild type and a cercosporin-sensitive mutant were characterized, including two ABC transporters (CnATR2, CnATR3), an MFS transporter (CnMFS2), a uracil transporter, and a zinc transport protein. Phylogenetic analysis showed that only CnATR3 clustered with transporters previously characterized to be involved in cercosporin resistance. Quantitative RT-PCR analysis of gene expression under conditions of cercosporin toxicity, however, showed that only CnATR2 was upregulated, thus this gene was selected for further characterization. Transformation and expression of CnATR2 in the cercosporin-sensitive fungus Neurospora crassa significantly increased cercosporin resistance. Targeted gene disruption of CnATR2 in the wild type C. nicotianae, however, did not decrease resistance. Expression analysis of other transporters in the cnatr2 mutant under conditions of cercosporin toxicity showed significant upregulation of the cercosporin facilitator protein gene (CFP), encoding an MFS transporter previously characterized as playing an important role in cercosporin autoresistance in Cercospora species. We conclude that cercosporin autoresistance in Cercospora is mediated by multiple genes, and that the fungus compensates for mutations by up-regulation of other resistance genes. CnATR2 may be a useful gene, alone or in addition to other known resistance genes, for engineering Cercospora resistance in crop plants. PMID:25862648

  8. Decreased sensitivity of artesunate and chloroquine of Plasmodium falciparum infecting hemoglobin H and/or hemoglobin constant spring erythrocytes.

    PubMed Central

    Yuthavong, Y; Butthep, P; Bunyaratvej, A; Fucharoen, S

    1989-01-01

    Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases). The IC50 for chloroquine were 97 +/- 46, 162 +/- 67, and 93 +/- 36 nM, respectively, in the variant erythrocytes, compared with 48 +/- 13 nM in normal erythrocytes (P less than 0.002, 0.002, and 0.02, respectively). The differences in sensitivity to artesunate and chloroquine of the parasite infecting HbH erythrocytes are probably related to their oxidative mode of action and relatively high amounts of antioxidant enzymes in the host erythrocytes. This novel example of dependence on the host of the malarial parasite drug sensitivity may have implications for chemotherapy of malaria in patients with genetically variant erythrocytes. PMID:2643631

  9. A novel ABCG-like transporter of Trypanosoma cruzi is involved in natural resistance to benznidazole

    PubMed Central

    Zingales, Bianca; Araujo, Rafael Gomes Aquino; Moreno, Margoth; Franco, Jaques; Aguiar, Pedro Henrique Nascimento; Nunes, Solange Lessa; Silva, Marcelo Nunes; Ienne, Susan; Machado, Carlos Renato; Brandão, Adeilton

    2015-01-01

    Benznidazole (BZ) is one of the two drugs used for Chagas disease treatment. Nevertheless therapeutic failures of BZ have been reported, which were mostly attributed to variable drug susceptibility among Trypanosoma cruzi strains. ATP-binding cassette (ABC) transporters are involved in a variety of translocation processes and some members have been implicated in drug resistance. Here we report the characterisation of the first T. cruzi ABCG transporter gene, named TcABCG1, which is over-expressed in parasite strains naturally resistant to BZ. Comparison of TcABCG1 gene sequence of two TcI BZ-resistant strains with CL Brener BZ-susceptible strain showed several single nucleotide polymorphisms, which determined 11 amino acid changes. CL Brener transfected with TcI transporter genes showed 40-47% increased resistance to BZ, whereas no statistical significant increment in drug resistance was observed when CL Brener was transfected with the homologous gene. Only in the parasites transfected with TcI genes there was 2-2.6-fold increased abundance of TcABCG1 transporter protein. The analysis in wild type strains also suggests that the level of TcABCG1 transporter is related to BZ natural resistance. The characteristics of untranslated regions of TcABCG1 genes of BZ-susceptible and resistant strains were investigated by computational tools. PMID:25946152

  10. Phosphate transport and arsenate resistance in the cyanobacterium Anabaena variabilis

    SciTech Connect

    Thiel, T.

    1988-03-01

    Cells of the cyanobacterium Anabaena variabilis starved for phosphate for 3 days took up phosphate at about 100 times the rate of unstarved cells.Kinetic data suggested that a new transport system had been induced by starvation for phosphate. The inducible phosphate transport system was quickly repressed by addition of P/sub i/. Phosphate-starved cells were more sensitive to the toxic effects of arsenate than were unstarved cells, but phosphate could alleviate some of the toxicity. Arsenate was a noncompetitive inhibitor of phosphate transport; however, the apparent K/sub i/ values were high, particularly for phosphate-replete cells. Preincubation of phosphate-starved cells with arsenate caused subsequent inhibition of phosphate transport, suggesting that intracellular arsenate inhibited phosphate transport. This effect was not seen in phosphate-replete cells.

  11. The ABC gene family in arthropods: comparative genomics and role in insecticide transport and resistance.

    PubMed

    Dermauw, Wannes; Van Leeuwen, Thomas

    2014-02-01

    About a 100 years ago, the Drosophila white mutant marked the birth of Drosophila genetics. The white gene turned out to encode the first well studied ABC transporter in arthropods. The ABC gene family is now recognized as one of the largest transporter families in all kingdoms of life. The majority of ABC proteins function as primary-active transporters that bind and hydrolyze ATP while transporting a large diversity of substrates across lipid membranes. Although extremely well studied in vertebrates for their role in drug resistance, less is known about the role of this family in the transport of endogenous and exogenous substances in arthropods. The ABC families of five insect species, a crustacean and a chelicerate have been annotated in some detail. We conducted a thorough phylogenetic analysis of the seven arthropod and human ABC protein subfamilies, to infer orthologous relationships that might suggest conserved function. Most orthologous relationships were found in the ABCB half transporter, ABCD, ABCE and ABCF subfamilies, but specific expansions within species and lineages are frequently observed and discussed. We next surveyed the role of ABC transporters in the transport of xenobiotics/plant allelochemicals and their involvement in insecticide resistance. The involvement of ABC transporters in xenobiotic resistance in arthropods is historically not well documented, but an increasing number of studies using unbiased differential gene expression analysis now points to their importance. We give an overview of methods that can be used to link ABC transporters to resistance. ABC proteins have also recently been implicated in the mode of action and resistance to Bt toxins in Lepidoptera. Given the enormous interest in Bt toxicology in transgenic crops, such findings will provide an impetus to further reveal the role of ABC transporters in arthropods. PMID:24291285

  12. Fate and transport of veterinary antibiotics, antibiotic-resistant bacteria, and antibiotic resistance gene from fields receiving poultry manure during storm events

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobials are used in production agriculture to treat disease and promote animal growth, but the presence of antibiotics in the environment raises concern about widespread antibiotic resistance. This study documents the occurrence and transport of tylosin, tetracycline, enterococci resistant to...

  13. Multidrug resistance in parasites: ABC transporters, P-glycoproteins and molecular modelling.

    PubMed

    Jones, P M; George, A M

    2005-04-30

    Parasitic diseases, caused by protozoa, helminths and arthropods, rank among the most important problems in human and veterinary medicine, and in agriculture, leading to debilitating sicknesses and loss of life. In the absence of vaccines and with the general failure of vector eradication programs, drugs are the main line of defence, but the newest drugs are being tracked by the emergence of resistance in parasites, sharing ominous parallels with multidrug resistance in bacterial pathogens. Any of a number of mechanisms will elicit a drug resistance phenotype in parasites, including: active efflux, reduced uptake, target modification, drug modification, drug sequestration, by-pass shunting, or substrate competition. The role of ABC transporters in parasitic multidrug resistance mechanisms is being subjected to more scrutiny, due in part to the established roles of certain ABC transporters in human diseases, and also to an increasing portfolio of ABC transporters from parasite genome sequencing projects. For example, over 100 ABC transporters have been identified in the Escherichia coli genome, but to date only about 65 in all parasitic genomes. Long established laboratory investigations are now being assisted by molecular biology, bioinformatics, and computational modelling, and it is in these areas that the role of ABC transporters in parasitic multidrug resistance mechanisms may be defined and put in perspective with that of other proteins. We discuss ABC transporters in parasites, and conclude with an example of molecular modelling that identifies a new interaction between the structural domains of a parasite P-glycoprotein. PMID:15826647

  14. Efficacy of Chloroquine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in Honduras

    PubMed Central

    Torres, Rosa Elena Mejia; Banegas, Engels Ilich; Mendoza, Meisy; Diaz, Cesar; Bucheli, Sandra Tamara Mancero; Fontecha, Gustavo A.; Alam, Md Tauqeer; Goldman, Ira; Udhayakumar, Venkatachalam; Zambrano, Jose Orlinder Nicolas

    2013-01-01

    Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization—World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras. PMID:23458957

  15. Transport and transformation of genetic information in the critical zone: The case of antibiotic resistance genes

    NASA Astrophysics Data System (ADS)

    Zhu, Y. G.

    2015-12-01

    In addition to material and energy flows, the dynamics and functions of the Earth's critical zone are intensively mediated by biological actions performed by diverse organisms. These biological actions are modulated by the expression of functional genes and their translation into enzymes that catalyze geochemical reactions, such as nutrient turnover and pollutant biodegradation. Although geobiology, as an interdisciplinary research area, is playing and vital role in linking biological and geochemical processes at different temporal and spatial scales, the distribution and transport of functional genes have rarely been investigated from the Earth's critical zone perspectives. To illustrate the framework of studies on the transport and transformation of genetic information in the critical zone, antibiotic resistance is taken as an example. Antibiotic resistance genes are considered as a group of emerging contaminants, and their emergence and spread within the critical zone on one hand are induced by anthropogenic activities, and on other hand are threatening human health worldwide. The transport and transformation of antibiotic resistance genes are controlled by both horizontal gene transfer between bacterial cells and the movement of bacteria harboring antibiotic resistance genes. In this paper, the fate and behavior of antibiotic resistance genes will be discussed in the following aspects: 1) general overview of environmental antibiotic resistance; 2) high through quantification of the resistome in various environmental media; 3) pathways of resistance gene flow within the critical zone; and 4) potential strategies in mitigating antibiotic resistance, particularly from the critical zone perspectives.

  16. Gas Transport Resistance in Polymer Electrolyte Thin Films on Oxygen Reduction Reaction Catalysts.

    PubMed

    Liu, Hang; Epting, William K; Litster, Shawn

    2015-09-15

    Significant reductions in expensive platinum catalyst loading for the oxygen reduction reaction are needed for commercially viable fuel cell electric vehicles as well as other important applications. In reducing loading, a resistance at the Pt surface in the presence of thin perfluorosulfonic acid (PFSA) electrolyte film, on the order of 10 nm thick, becomes a significant barrier to adequate performance. However, the resistance mechanism is unresolved and could be due to gas dissolution kinetics, increased diffusion resistance in thin films, or electrolyte anion interactions. A common hypothesis for the origin of the resistance is a highly reduced oxygen permeability in the thin polymer electrolyte films that coat the catalyst relative to bulk permeability that is caused by nanoscale confinement effects. Unfortunately, the prior work has not separated the thin-film gas transport resistance from that associated with PFSA interactions with a polarized catalyst surface. Here, we present the first characterization of the thin-film O2 transport resistance in the absence of a polarized catalyst, using a nanoporous substrate that geometrically mimics the active catalyst particles. Through a parametric study of varying PFSA film thickness, as thin as 50 nm, we observe no enhanced gas transport resistance in thin films as a result of either interfacial effects or structural changes in the PFSA. Our results suggest that other effects, such as anion poisoning at the Pt catalyst, could be the source of the additional resistance observed at low Pt loading. PMID:26299282

  17. Transport of antibiotic-resistant Escherichia coli in a public rural karst water supply

    NASA Astrophysics Data System (ADS)

    Laroche, Emilie; Petit, Fabienne; Fournier, Matthieu; Pawlak, Barbara

    2010-10-01

    SummaryThe goal of this study was to determine the conditions promoting the transport of antibiotic-resistant faecal bacteria, in a rural karst system providing drinking water (Northwest France). For this purpose, the resistance of the Escherichia coli population (436 isolates) to 17 antibiotics was investigated by analysing water samples from four representative interconnected sites: a creek, a swallow hole, a spring, and a well. The samples were collected during four contrasting hydrologic and grazing periods. The transport of resistant E. coli from the creek to the well appeared to be dominated by run-off and leaching phenomena. Less than 7% of the E. coli isolated during a wet period without grazing or during a dry period with grazing were antibiotic-resistant, whereas, during rainfall events with grazing, between 30% and 55% of the E. coli detected were resistant; 10-23% of these isolates were resistant to two or three antibiotics. The resistance most often found was to either chloramphenicol or tetracycline. To better describe the dynamics of the antibiotic-resistant population of E. coli entering the karst aquifer, the swallow hole was monitored over a 24-h period during a rainfall event (90 isolates). The antibiotic resistance of E. coli isolates and the occurrence of class 1 integrons, genetic elements involved multi-resistance, were determined. The origin of this E. coli population was also investigated. This monitoring demonstrated that multi-antibiotic-resistant E. coli, representing 23% of the total population, infiltrated the karst aquifer at the peak of a rainfall event, with some isolates being resistant to up to eight antibiotics. No intI1 gene was detected. The search for the origin of the resistant E. coli isolated during this rainfall event demonstrated that they were of both animal and human origin. This work demonstrates that drinking water resources taken from the groundwater in a rural karst terrain is vulnerable to contamination by

  18. Chloroquine in the treatment of porphyria cutanea tarda.

    PubMed

    Tsega, E; Besrat, A; Damtew, B; Seyoum, E; Landells, J W

    1981-01-01

    Porphyria cutanea tarda (PCT) is common in Ethiopia and invariably affects the liver. Treatment by abstension from alcohol and avoidance of direct sunlight often failed to achieve lasting improvement. Phlebotomy is unacceptable to most of our patients and impractical as a routine therapy. Chloroquine phosphate 500 mg (300 mg base) given daily for 10 days to 24 patients with confirmed PCT, was found to be uniformly effective. Both clinical and biochemical remissions were complete, The side effects of chloroquine include fever, nausea, vomiting and myalgia which predictably occur on the third day of therapy and subside within 72 hours. Since all other modes of therapy are ineffective or impractical and since the response to chloroquine is prompt, effective and reproducible and the side effects are brief, mild and do not cause permanent hepatic damage, it is suggested that this drug is currently the most practical treatment for PCT in areas where repeated phlebotomy is unacceptable and patient follow-up is unsatisfactory. PMID:7324107

  19. Probenecid-resistant J774 cell expression of enhanced organic anion transport by a mechanism distinct from multidrug resistance.

    PubMed

    Cao, C; Steinberg, T H; Neu, H C; Cohen, D; Horwitz, S B; Hickman, S; Silverstein, S C

    1993-08-01

    Macrophages possess organic anion transporters that carry membrane-impermeant fluorescent dyes, such as lucifer yellow (LY) and carboxy-fluorescein, from the cytoplasm into endosomes and out of the cells. Probenecid, an organic anion transport inhibitor, blocks these processes. Prolonged incubation of J774 cells in medium containing 2.5 mM probenecid eventually kills most of these cells. To identify J774 variants that express increased organic anion transport activity, we selected probenecid-resistant (PBR) J774 cells by growing them in medium containing increasing concentrations of probenecid. When PBR and unselected J774 cells were loaded with LY by ATP4- permeabilization, the amount of LY accumulated by the PBR cells was about half that in the unselected cells. This difference was abolished by adding 10 mM probenecid to the medium in which the cells were loaded, suggesting that the diminished LY accumulation in PBR cells was due to enhanced LY secretion and that the PBR cells expressed increased organic anion transport activity. Direct comparison of LY efflux from J774 and PBR J774 cells showed a faster initial rate of secretion of LY from PBR J774 cells than from unselected J774 cells. To determine whether LY efflux is mediated by P-glycoprotein, we compared LY efflux in unselected J774 cells, PBR J774 cells, and multidrug-resistant J774 cells (J7.C1). LY efflux from J7.C1 cells was not sensitive to verapamil, which inhibits multidrug-resistance transporters, and reverses the multidrug-resistant phenotype of J7.C1 cells. The rates of LY efflux from unselected J774 and J7.C1 cells were virtually identical.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7909709

  20. The resistance to impact of spent Magnox fuel transport flasks

    SciTech Connect

    Not Available

    1985-01-01

    This book completes the papers of the four-year programme of research and demonstrations embarked upon by the CEGB in 1981, culminating in the spectacular train crash at Old Dalby in July 1984. It explains the CEGB's operations in relation to the transportation of spent Magnox fuel. The public tests described in this book are more effective in improving public understanding and confidence than any amount of explanations could have been, raising the wider question of how best the scientific community can respond to the legitimate concerns of the man and woman in the street about the generating of electricity from nuclear power. The contents are: Taking care; irradiated fuel transport in the UK; programming for flask safety; the use of scale models in impact testing; flask analytical studies; drop test facilities; demonstration drop test; a study of flask transport impact hazards; impact of Magnox irradiated fuel transport flasks into rock and concrete; rail crash demonstration scenarios; horizontal impact testing of quarter scale flasks using masonry targets; horizontal crash testing and analysis of model flatrols; flatrol test; analysis of full scale impact into an abutment; analysis of primary impact forces in the train crash demonstration; horizontal impact tests of quarter scale Magnox flasks and stylised model locomotives; predictive estimates for behaviour in the train crash demonstration; design and organization of the crash; execution of the crash demonstration by British Rail; instrumentation for the train crash demonstration; photography for the crash demonstration; a summary of the CEGB's flask accident impact studies.

  1. Resistivity and induced polarization monitoring of salt transport under natural hydraulic gradients

    SciTech Connect

    Slater, L.D.; Sandberg, S.K.

    2000-04-01

    The authors demonstrate the use of resistivity/induced polarization (IP) monitoring of salt transport under natural hydraulic loads. Electrical monitoring of saline tracer transport during forced injection has been demonstrated previously. Detection of tracer transport under natural hydraulic loading is difficult because neither the hydraulic load nor the tracer resistivity can be controlled. In one study, the authors identify the electrical response to salt transport in a dynamic beach environment. Resistivity/IP imagine resolved the structure of the saltwater-freshwater interface and evidence for tide-induced groundwater transport. Resistivity increases in the near surface and at depth, upbeach of the high-tide mark, accompanied by tidal transgression. They attribute this to desaturation and decreasing salinity in the near surface and to decreasing salinity at depth, despite tidal transgression. Monitoring of groundwater levels indicates a phase lag between the tide level and groundwater level, supporting the electrical data. IP was insensitive to groundwater salinity variation. In a second study, the authors identify the electrical response to recharge-induced salt transport from a road-sale storage facility. Conductivity and IP models for monitoring lines, located on the basis of an EM31 survey, resolved the subsurface salt distribution, IP modeling resolved the sediment-bedrock interface. Modeling of monthly conductivity differences revealed conductivity increases and decreases at the locations of salt contamination, which correlate with the recharge pattern. They attribute near-surface conductivity increases after heavy rainfall to increasing saturation and ion dissolution. Corresponding conductivity decreases at depth are attributed to flushing of the bedrock with freshwater. Essentially, the opposite response was observed during a quiet monitoring period following heavy recharge. Near-surface IP changes are consistent with this interpretation. Salt

  2. Experimental study on the resistance of a transport ship navigating in level ice

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Sun, Jianqiao; Ji, Shaopeng; Tian, Yukui

    2016-06-01

    This study investigates the resistance of a transport ship navigating in Arctic waters by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and the ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist (1989) for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.

  3. Experimental study on the resistance of a transport ship navigating in level ice

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Sun, Jianqiao; Ji, Shaopeng; Tian, Yukui

    2016-04-01

    This study investigates the resistance of a transport ship navigating in Arctic waters by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and the ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist (1989) for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.

  4. Identification of Aspergillus fumigatus multidrug transporter genes and their potential involvement in antifungal resistance.

    PubMed

    Meneau, Isabelle; Coste, Alix T; Sanglard, Dominique

    2016-08-01

    Aspergillus fumigatus can cause severe fatal invasive aspergillosis in immunocompromised patients but is also found in the environment. A. fumigatus infections can be treated with antifungals agents among which azole and echinocandins. Resistance to the class of azoles has been reported not only from patient samples but also from environmental samples. Azole resistance mechanisms involve for most isolates alterations at the site of the azole target (cyp51A); however, a substantial number of isolates can also exhibit non-cyp51A-mediated mechanisms.We aimed here to identify novel A. fumigatus genes involved in azole resistance. For this purpose, we designed a functional complementation system of A. fumigatus cDNAs expressed in a Saccharomyces cerevisiae isolate lacking the ATP Binding Cassette (ABC) transporter PDR5 and that was therefore more azole-susceptible than the parent wild type. Several genes were recovered including two distinct ABC transporters (atrF, atrI) and a Major Facilitator transporter (mdrA), from which atrI (Afu3g07300) and mdrA (Afu1g13800) were not yet described. atrI mediated resistance to itraconazole and voriconazole, while atrF only to voriconazole in S. cerevisiae Gene inactivation of each transporter in A. fumigatus indicated that the transporters were involved in the basal level of azole susceptibility. The expression of the transporters was addressed in clinical and environmental isolates with several azole resistance profiles. Our results show that atrI and mdrA tended to be expressed at higher levels than atrF in normal growth conditions. atrF was upregulated in 2/4 of azole-resistant environmental isolates and was the only gene with a significant association between transporter expression and azole resistance. In conclusion, this work showed the potential of complementation to identify functional transporters. The identified transporters were suggested to participate in azole resistance of A. fumigatus; however, this hypothesis will

  5. Research Progress on the Role of ABC Transporters in the Drug Resistance Mechanism of Intractable Epilepsy

    PubMed Central

    Xiong, Jie; Mao, Ding-an; Liu, Li-qun

    2015-01-01

    The pathogenesis of intractable epilepsy is not fully clear. In recent years, both animal and clinical trials have shown that the expression of ATP-binding cassette (ABC) transporters is increased in patients with intractable epilepsy; additionally, epileptic seizures can lead to an increase in the number of sites that express ABC transporters. These findings suggest that ABC transporters play an important role in the drug resistance mechanism of epilepsy. ABC transporters can perform the funcions of a drug efflux pump, which can reduce the effective drug concentration at epilepsy lesions by reducing the permeability of the blood brain barrier to antiepileptic drugs, thus causing resistance to antiepileptic drugs. Given the important role of ABC transporters in refractory epilepsy drug resistance, antiepileptic drugs that are not substrates of ABC transporters were used to obtain ABC transporter inhibitors with strong specificity, high safety, and few side effects, making them suitable for long-term use; therefore, these drugs can be used for future clinical treatment of intractable epilepsy. PMID:26491660

  6. Hot electron transport modelling in fast ignition relevant targets with non-Spitzer resistivity

    NASA Astrophysics Data System (ADS)

    Chapman, D. A.; Hughes, S. J.; Hoarty, D. J.; Swatton, D. J. R.

    2010-08-01

    The simple Lee-More model for electrical resistivity is implemented in the hybrid fast electron transport code THOR. The model is shown to reproduce experimental data across a wide range of temperatures using a small number of parameters. The effect of this model on the heating of simple Al targets by a short-pulse laser is studied and compared to the predictions of the classical Spitzer-Härm resistivity. The model is then used in simulations of hot electron transport experiments using buried layer targets.

  7. Auxin transport in an auxin-resistant mutant of arabidopsis thaliana

    SciTech Connect

    Lincoln, C.; Benning, C.; Estelle, M.

    1987-04-01

    The authors are studying a group of allelic recessive mutations in Arabidopsis called axr-1. Homozygous axr-1 plants are resistant to exogenously applied auxin. In addition, axr-1 mutations all confer a number of development abnormalities including an apparent reduction in apical dominance, loss of normal geotropic response, and a failure to self-fertilize due to a decrease in stamen elongation. In order to determine whether this pleiotropic phenotype is due to an alteration in auxin transport they have adapted the agar block transport assay for use in Arabidopsis stem segments. Their results indicate that as in other plant species, auxin transport is strongly polar in Arabidopsis stem segments. In addition transport is inhibited by the well characterized auxin transport inhibitor N-1-naphthylphthalamic acid and the artificial auxin 2,4-D. These results as well as the characterization of transport in axr-1 plants will be presented.

  8. 2,4-D resistance in wild radish: reduced herbicide translocation via inhibition of cellular transport

    PubMed Central

    Goggin, Danica E.; Cawthray, Gregory R.; Powles, Stephen B.

    2016-01-01

    Resistance to auxinic herbicides is increasing in a range of dicotyledonous weed species, but in most cases the biochemical mechanism of resistance is unknown. Using 14C-labelled herbicide, the mechanism of resistance to 2,4-dichlorophenoxyacetic acid (2,4-D) in two wild radish (Raphanus raphanistrum L.) populations was identified as an inability to translocate 2,4-D out of the treated leaf. Although 2,4-D was metabolized in wild radish, and in a different manner to the well-characterized crop species wheat and bean, there was no difference in metabolism between the susceptible and resistant populations. Reduced translocation of 2,4-D in the latter was also not due to sequestration of the herbicide, or to reduced uptake by the leaf epidermis or mesophyll cells. Application of auxin efflux or ABCB transporter inhibitors to 2,4-D-susceptible plants caused a mimicking of the reduced-translocation resistance phenotype, suggesting that 2,4-D resistance in the populations under investigation could be due to an alteration in the activity of a plasma membrane ABCB-type auxin transporter responsible for facilitating long-distance transport of 2,4-D. PMID:26994475

  9. Overcoming ABC transporter-mediated multidrug resistance: Molecular mechanisms and novel therapeutic drug strategies.

    PubMed

    Li, Wen; Zhang, Han; Assaraf, Yehuda G; Zhao, Kun; Xu, Xiaojun; Xie, Jinbing; Yang, Dong-Hua; Chen, Zhe-Sheng

    2016-07-01

    Multidrug resistance is a key determinant of cancer chemotherapy failure. One of the major causes of multidrug resistance is the enhanced efflux of drugs by membrane ABC transporters. Targeting ABC transporters projects a promising approach to eliminating or suppressing drug resistance in cancer treatment. To reveal the functional mechanisms of ABC transporters in drug resistance, extensive studies have been conducted from identifying drug binding sites to elucidating structural dynamics. In this review article, we examined the recent crystal structures of ABC proteins to depict the functionally important structural elements, such as domains, conserved motifs, and critical amino acids that are involved in ATP-binding and drug efflux. We inspected the drug-binding sites on ABC proteins and the molecular mechanisms of various substrate interactions with the drug binding pocket. While our continuous battle against drug resistance is far from over, new approaches and technologies have emerged to push forward our frontier. Most recent developments in anti-MDR strategies include P-gp inhibitors, RNA-interference, nano-medicines, and delivering combination strategies. With the advent of the 'Omics' era - genomics, epigenomics, transcriptomics, proteomics, and metabolomics - these disciplines play an important role in fighting the battle against chemoresistance by further unraveling the molecular mechanisms of drug resistance and shed light on medical therapies that specifically target MDR. PMID:27449595

  10. 2,4-D resistance in wild radish: reduced herbicide translocation via inhibition of cellular transport.

    PubMed

    Goggin, Danica E; Cawthray, Gregory R; Powles, Stephen B

    2016-05-01

    Resistance to auxinic herbicides is increasing in a range of dicotyledonous weed species, but in most cases the biochemical mechanism of resistance is unknown. Using (14)C-labelled herbicide, the mechanism of resistance to 2,4-dichlorophenoxyacetic acid (2,4-D) in two wild radish (Raphanus raphanistrum L.) populations was identified as an inability to translocate 2,4-D out of the treated leaf. Although 2,4-D was metabolized in wild radish, and in a different manner to the well-characterized crop species wheat and bean, there was no difference in metabolism between the susceptible and resistant populations. Reduced translocation of 2,4-D in the latter was also not due to sequestration of the herbicide, or to reduced uptake by the leaf epidermis or mesophyll cells. Application of auxin efflux or ABCB transporter inhibitors to 2,4-D-susceptible plants caused a mimicking of the reduced-translocation resistance phenotype, suggesting that 2,4-D resistance in the populations under investigation could be due to an alteration in the activity of a plasma membrane ABCB-type auxin transporter responsible for facilitating long-distance transport of 2,4-D. PMID:26994475

  11. Resistance/susceptibility to lethal Sendai virus infection genetically linked to a mucociliary transport polymorphism.

    PubMed Central

    Brownstein, D G

    1987-01-01

    Linkage was tested between a mucociliary transport polymorphism and resistance/susceptibility to lethal Sendai virus infection in segregant hybrid mice of C57BL/6J and DBA/2J parents. The distribution of paired phenotypes for tracheal mucociliary transport rates and susceptibility to lethal Sendai virus infection in 171 F1 X DBA/2J mice showed strong interaction of the parental phenotypes. PMID:3033294

  12. Therapeutic Responses of Plasmodium vivax Malaria to Chloroquine and Primaquine Treatment in Northeastern Myanmar

    PubMed Central

    Yuan, Lili; Wang, Ying; Parker, Daniel M.; Gupta, Bhavna; Yang, Zhaoqing; Liu, Huaie; Fan, Qi; Cao, Yaming; Xiao, Yuping; Lee, Ming-chieh; Zhou, Guofa; Yan, Guiyun; Baird, J. Kevin

    2014-01-01

    Chloroquine-primaquine (CQ-PQ) continues to be the frontline therapy for radical cure of Plasmodium vivax malaria. Emergence of CQ-resistant (CQR) P. vivax parasites requires a shift to artemisinin combination therapies (ACTs), which imposes a significant financial, logistical, and safety burden. Monitoring the therapeutic efficacy of CQ is thus important. Here, we evaluated the therapeutic efficacy of CQ-PQ for P. vivax malaria in northeast Myanmar. We recruited 587 patients with P. vivax monoinfection attending local malaria clinics during 2012 to 2013. These patients received three daily doses of CQ at a total dose of 24 mg of base/kg of body weight and an 8-day PQ treatment (0.375 mg/kg/day) commencing at the same time as the first CQ dose. Of the 401 patients who finished the 28-day follow-up, the cumulative incidence of recurrent parasitemia was 5.20% (95% confidence interval [CI], 3.04% to 7.36%). Among 361 (61%) patients finishing a 42-day follow-up, the cumulative incidence of recurrent blood-stage infection reached 7.98% (95% CI, 5.20% to 10.76%). The cumulative risk of gametocyte carriage at days 28 and 42 was 2.21% (95% CI, 0.78% to 3.64%) and 3.93% (95% CI, 1.94% to 5.92%), respectively. Interestingly, for all 15 patients with recurrent gametocytemia, this was associated with concurrent asexual stages. Genotyping of recurrent parasites at the merozoite surface protein 3α gene locus from 12 patients with recurrent parasitemia within 28 days revealed that 10 of these were the same genotype as at day 0, suggesting recrudescence or relapse. Similar studies in 70 patients in the same area in 2007 showed no recurrent parasitemias within 28 days. The sensitivity to chloroquine of P. vivax in northeastern Myanmar may be deteriorating. PMID:25512415

  13. The LABCG2 Transporter from the Protozoan Parasite Leishmania Is Involved in Antimony Resistance.

    PubMed

    Perea, Ana; Manzano, José Ignacio; Castanys, Santiago; Gamarro, Francisco

    2016-06-01

    Treatment for leishmaniasis, which is caused by Leishmania protozoan parasites, currently relies on a reduced arsenal of drugs. However, the significant increase in the incidence of drug therapeutic failure and the growing resistance to first-line drugs like antimonials in some areas of Northern India and Nepal limit the control of this parasitic disease. Understanding the molecular mechanisms of resistance in Leishmania is now a matter of urgency to optimize drugs used and to identify novel drug targets to block or reverse resistant mechanisms. Some members of the family of ATP-binding cassette (ABC) transporters in Leishmania have been associated with drug resistance. In this study, we have focused our interest to characterize LABCG2's involvement in drug resistance in Leishmania. Leishmania major parasites overexpressing the ABC protein transporter LABCG2 were generated in order to assess how LABCG2 is involved in drug resistance. Assays of susceptibility to different leishmanicidal agents were carried out. Analysis of the drug resistance profile revealed that Leishmania parasites overexpressing LABCG2 were resistant to antimony, as they demonstrated a reduced accumulation of Sb(III) due to an increase in drug efflux. Additionally, LABCG2 was able to transport thiols in the presence of Sb(III) Biotinylation assays using parasites expressing LABCG2 fused with an N-terminal green fluorescent protein tag revealed that LABCG2 is partially localized in the plasma membrane; this supports data from previous studies which suggested that LABCG2 is localized in intracellular vesicles that fuse with the plasma membrane during exocytosis. In conclusion, Leishmania LABCG2 probably confers antimony resistance by sequestering metal-thiol conjugates within vesicles and through further exocytosis by means of the parasite's flagellar pocket. PMID:27021316

  14. The transport of antibiotic resistance genes and residues in groundwater near swine production facilities

    NASA Astrophysics Data System (ADS)

    Lin, Y. F.; Yannarell, A. C.; Mackie, R. I.; Krapac, I. G.; Chee-Sanford, J. S.; Koike, S.

    2008-12-01

    The use of antibiotics at concentrated animal feeding operations (CAFOs) for disease prevention, disease treatment, and growth promotion can contribute to the spread of antibiotic compounds, their breakdown products, and antibiotic resistant bacteria and/or the genes that confer resistance. In addition, constitutive use of antibiotics at sub-therapeutic levels can select for antibiotic resistance among the bacteria that inhabit animal intestinal tracts, onsite manure treatment facilities, and any environments receiving significant inputs of manure (e.g. through waste lagoon leakage or fertilizer amendments to farm soils). If the antibiotic resistant organisms persist in these new environments, or if they participate in genetic exchanges with the native microflora, then CAFOs may constitute a significant reservoir for the spread of antibiotic resistance to the environment at large. Our results have demonstrated that leakage from waste treatment lagoons can influence the presence and persistence of tetracycline resistance genes in the shallow aquifer adjacent to swine CAFOs, and molecular phylogeny allowed us to distinguish "native" tetracycline resistance genes in control groundwater wells from manure-associated genes introduced from the lagoon. We have also been able to detect the presence of erythromycin resistance genes in CAFO surface and groundwater even though erythromycin is strictly reserved for use in humans and thus is not utilized at any of these sites. Ongoing research, including modeling of particle transport in groundwater, will help to determine the potential spatial and temporal extent of CAFO-derived antibiotic resistance.

  15. Antimalarial activity of ruthenium(II) and osmium(II) arene complexes with mono- and bidentate chloroquine analogue ligands.

    PubMed

    Ekengard, Erik; Glans, Lotta; Cassells, Irwin; Fogeron, Thibault; Govender, Preshendren; Stringer, Tameryn; Chellan, Prinessa; Lisensky, George C; Hersh, William H; Doverbratt, Isa; Lidin, Sven; de Kock, Carmen; Smith, Peter J; Smith, Gregory S; Nordlander, Ebbe

    2015-11-28

    Eight new ruthenium and five new osmium p-cymene half-sandwich complexes have been synthesized, characterized and evaluated for antimalarial activity. All complexes contain ligands that are based on a 4-chloroquinoline framework related to the antimalarial drug chloroquine. Ligands HL(1-8) are salicylaldimine derivatives, where HL(1) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine, and HL(2-8) contain non-hydrogen substituents in the 3-position of the salicylaldimine ring, viz. F, Cl, Br, I, NO2, OMe and (t)Bu for HL(2-8), respectively. Ligand HL(9) is also a salicylaldimine-containing ligand with substitutions in both 3- and 5-positions of the salicylaldimine moiety, i.e. N-(2-((2-hydroxy-3,5-di-tert-butylphenyl)methyl-imino)ethyl)-7-chloroquinolin-4-amine, while HL(10) is N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) The half sandwich metal complexes that have been investigated are [Ru(η(6)-cym)(L(1-8))Cl] (Ru-1-Ru-8, cym = p-cymene), [Os(η(6)-cym)(L(1-3,5,7))Cl] (Os-1-Os-3, Os-5, and Os-7), [M(η(6)-cym)(HL(9))Cl2] (M = Ru, Ru-HL(9); M = Os, Os-HL(9)) and [M(η(6)-cym)(L(10))Cl]Cl (M = Ru, Ru-10; M = Os, Os-10). In complexes Ru-1-Ru-8 and Ru-10, Os-1-Os-3, Os-5 and Os-7 and Os-10, the ligands were found to coordinate as bidentate N,O- and N,N-chelates, while in complexes Ru-HL(9) and Os-HL(9), monodentate coordination of the ligands through the quinoline nitrogen was established. The antimalarial activity of the new ligands and complexes was evaluated against chloroquine sensitive (NF54 and D10) and chloroquine resistant (Dd2) Plasmodium falciparum malaria parasite strains. Coordination of ruthenium and osmium arene moieties to the ligands resulted in lower antiplasmodial activities relative to the free ligands, but the resistance index is better for the ruthenium complexes compared to chloroquine. Overall, osmium complexes appeared to be less active than the corresponding ruthenium complexes. PMID:26491831

  16. The Effect of Chloroquine on Immune Activation and Interferon Signatures Associated with HIV-1.

    PubMed

    Jacobson, Jeffrey M; Bosinger, Steven E; Kang, Minhee; Belaunzaran-Zamudio, Pablo; Matining, Roy M; Wilson, Cara C; Flexner, Charles; Clagett, Brian; Plants, Jill; Read, Sarah; Purdue, Lynette; Myers, Laurie; Boone, Linda; Tebas, Pablo; Kumar, Princy; Clifford, David; Douek, Daniel; Silvestri, Guido; Landay, Alan L; Lederman, Michael M

    2016-07-01

    Immune activation associated with HIV-1 infection contributes to morbidity and mortality. We studied whether chloroquine, through Toll-like receptor (TLR) antagonist properties, could reduce immune activation thought to be driven by TLR ligands, such as gut-derived bacterial elements and HIV-1 RNAs. AIDS Clinical Trials Group A5258 was a randomized, double-blind, placebo-controlled study in 33 HIV-1-infected participants off antiretroviral therapy (ART) and 37 participants on ART. Study participants in each cohort were randomized 1:1 to receive chloroquine 250 mg orally for the first 12 weeks then cross over to placebo for 12 weeks or placebo first and then chloroquine. Combining the periods of chloroquine use in both arms of the on-ART cohort yielded a modest reduction in the proportions of CD8 T cells co-expressing CD38 and DR (median decrease = 3.0%, p = .003). The effect on immune activation in the off-ART cohort was likely confounded by increased plasma HIV-1 RNA during chloroquine administration (median 0.29 log10 increase, p < .001). Transcriptional analyses in the off-ART cohort showed decreased expression of interferon-stimulated genes in 5 of 10 chloroquine-treated participants and modest decreases in CD38 and CCR5 RNAs in all chloroquine-treated participants. Chloroquine modestly reduced immune activation in ART-treated HIV-infected participants. Clinical Trials Registry Number: NCT00819390. PMID:26935044

  17. Performance of Four Transport and Storage Systems for Molecular Detection of Multidrug-Resistant Tuberculosis

    PubMed Central

    Rabodoarivelo, Marie Sylvianne; Imperiale, Bélen; andrianiavomikotroka, Rina; Brandao, Angela; Kumar, Parveen; Singh, Sarman; Ferrazoli, Lucilaine; Morcillo, Nora; Rasolofo, Voahangy; Palomino, Juan Carlos; Vandamme, Peter; Martin, Anandi

    2015-01-01

    Background Detection of drug-resistant tuberculosis is essential for the control of the disease but it is often hampered by the limitation of transport and storage of samples from remote locations to the reference laboratory. We performed a retrospective field study to evaluate the performance of four supports enabling the transport and storage of samples to be used for molecular detection of drug resistance using the GenoType MTBDRplus. Methods Two hundred Mycobacterium tuberculosis strains were selected and spotted on slides, FTA cards, GenoCards, and in ethanol. GenoType MTBDRplus was subsequently performed with the DNA extracted from these supports. Sensitivity and specificity were calculated and compared to the results obtained by drug susceptibility testing. Results For all supports, the overall sensitivity and specificity for detection of resistance to RIF was between 95% and 100%, and for INH between 95% and 98%. Conclusion The four transport and storage supports showed a good sensitivity and specificity for the detection of resistance to RIF and INH in M. tuberculosis strains using the GenoType MTBDRplus. These supports can be maintained at room temperature and could represent an important alternative cost-effective method useful for rapid molecular detection of drug-resistant TB in low-resource settings. PMID:26431352

  18. Transport proteins determine drug sensitivity and resistance in a protozoan parasite, Trypanosoma brucei

    PubMed Central

    Munday, Jane C.; Settimo, Luca; de Koning, Harry P.

    2015-01-01

    Drug resistance in pathogenic protozoa is very often caused by changes to the ‘transportome’ of the parasites. In Trypanosoma brucei, several transporters have been implicated in uptake of the main classes of drugs, diamidines and melaminophenyl arsenicals. The resistance mechanism had been thought to be due to loss of a transporter known to carry both types of agents: the aminopurine transporter P2, encoded by the gene TbAT1. However, although loss of P2 activity is well-documented as the cause of resistance to the veterinary diamidine diminazene aceturate (DA; Berenil®), cross-resistance between the human-use arsenical melarsoprol and the diamidine pentamidine (melarsoprol/pentamidine cross resistance, MPXR) is the result of loss of a separate high affinity pentamidine transporter (HAPT1). A genome-wide RNAi library screen for resistance to pentamidine, published in 2012, gave the key to the genetic identity of HAPT1 by linking the phenomenon to a locus that contains the closely related T. brucei aquaglyceroporin genes TbAQP2 and TbAQP3. Further analysis determined that knockdown of only one pore, TbAQP2, produced the MPXR phenotype. TbAQP2 is an unconventional aquaglyceroporin with unique residues in the “selectivity region” of the pore, and it was found that in several MPXR lab strains the WT gene was either absent or replaced by a chimeric protein, recombined with parts of TbAQP3. Importantly, wild-type AQP2 was also absent in field isolates of T. b. gambiense, correlating with the outcome of melarsoprol treatment. Expression of a wild-type copy of TbAQP2 in even the most resistant strain completely reversed MPXR and re-introduced HAPT1 function and transport kinetics. Expression of TbAQP2 in Leishmania mexicana introduced a pentamidine transport activity indistinguishable from HAPT1. Although TbAQP2 has been shown to function as a classical aquaglyceroporin it is now clear that it is also a high affinity drug transporter, HAPT1. We discuss here a

  19. Electrical resistance and transport numbers of ion-exchange membranes used in electrodialytic soil remediation

    SciTech Connect

    Hansen, H.K.; Ottosen, L.M.; Villumsen, A.

    1999-08-01

    Electrodialytic soil remediation is a recently developed method to decontaminate heavy metal polluted soil using ion-exchange membranes. In this method one side of the ion-exchange membrane is in direct contact with the polluted soil. It is of great importance to known if this contact with the soil causes damage to the membrane. This work presents the result of transport number and electrical resistance measurements done on four sets of ion-exchange membranes (Ionics, Inc CR67 HMR412 cation-exchange membranes and Ionics, Inc AR204 SXZR anion-exchange membranes), which have been used in four different electrodialytic soil remediation experiments. The experiments showed that after the use in electrodialytic soil remediation, the ion-exchange membranes had transport numbers in the same magnitude as new membranes. The electrical resistance for six membranes did not differ from that of new membranes, whereas two membranes showed a slightly increased resistance.

  20. Heat and mass transport resistances in vacuum membrane distillation per drop

    SciTech Connect

    Bandini, S.; Sarti, G.C.

    1999-07-01

    Vacuum membrane distillation (VMD) is a separation process based on the use of microporous hydrophobic membranes. The membrane is located between an aqueous phase and a permeate, which is kept under vacuum at pressure values below the equilibrium vapor pressure of the feed. The liquid stream vaporizes at one side of the membrane, and the vapors diffuse through the gas phase inside the membrane pores. The process rate and performance are affected highly by the transport phenomena both in the liquid phase and through the membrane. Heat- and mass-transfer resistance in the liquid phase, as well as mass-transfer resistance through the membrane, play an important role in determining the process performance. Based on VMD experimental data for several binary aqueous mixtures containing volatile organic compounds, a simple criterion to investigate the role of each transport resistance on the separation efficiency is discussed.

  1. Piperaquine and Lumefantrine resistance in Plasmodium berghei ANKA associated with increased expression of Ca2+/H+ antiporter and glutathione associated enzymes.

    PubMed

    Kiboi, Daniel; Irungu, Beatrice; Orwa, Jennifer; Kamau, Luna; Ochola-Oyier, Lynette Isabella; Ngángá, Joseph; Nzila, Alexis

    2014-12-01

    We investigated the mechanisms of resistance of two antimalarial drugs piperaquine (PQ) and lumefantrine (LM) using the rodent parasite Plasmodium berghei as a surrogate of the human parasite, Plasmodium falciparum. We analyzed the whole coding sequence of Plasmodium berghei chloroquine resistance transporter (Pbcrt) and Plasmodium berghei multidrug resistance gene 1(Pbmdr-1) for polymorphisms. These genes are associated with quinoline resistance in Plasmodium falciparum. No polymorphic changes were detected in the coding sequences of Pbcrt and Pbmdr1 or in the mRNA transcript levels of Pbmdr1. However, our data demonstrated that PQ and LM resistance is achieved by multiple mechanisms that include elevated mRNA transcript levels of V-type H(+) pumping pyrophosphatase (vp2), Ca(2+)/H(+) antiporter (vcx1), gamma glutamylcysteine synthetase (ggcs) and glutathione-S-transferase (gst) genes, mechanisms also known to contribute to chloroquine resistance in P. falciparum and rodent malaria parasites. The increase in ggcs and gst transcript levels was accompanied by high glutathione (GSH) levels and elevated activity of glutathione-S-transferase (GST) enzyme. Taken together, these results demonstrate that Pbcrt and Pbmdr1 are not associated with PQ and LM resistance in P. berghei ANKA, while vp2, vcx1, ggcs and gst may mediate resistance directly or modulate functional mutations in other unknown genes. PMID:25448357

  2. A Transporter Interactome Is Essential for the Acquisition of Antimicrobial Resistance to Antibiotics

    PubMed Central

    Shuster, Yonatan; Steiner-Mordoch, Sonia; Alon Cudkowicz, Noemie; Schuldiner, Shimon

    2016-01-01

    Awareness of the problem of antimicrobial resistance (AMR) has escalated and drug-resistant infections are named among the most urgent problems facing clinicians today. Our experiments here identify a transporter interactome and portray its essential function in acquisition of antimicrobial resistance. By exposing E. coli cells to consecutive increasing concentrations of the fluoroquinolone norfloxacin we generated in the laboratory highly resistant strains that carry multiple mutations, most of them identical to those identified in clinical isolates. With this experimental paradigm, we show that the MDTs function in a coordinated mode to provide an essential first-line defense mechanism, preventing the drug reaching lethal concentrations, until a number of stable efficient alterations occur that allow survival. Single-component efflux transporters remove the toxic compounds from the cytoplasm to the periplasmic space where TolC-dependent transporters expel them from the cell. We postulate a close interaction between the two types of transporters to prevent rapid leak of the hydrophobic substrates back into the cell. The findings change the prevalent concept that in Gram-negative bacteria a single multidrug transporter, AcrAB-TolC type, is responsible for the resistance. The concept of a functional interactome, the process of identification of its members, the elucidation of the nature of the interactions and its role in cell physiology will change the existing paradigms in the field. We anticipate that our work will have an impact on the present strategy searching for inhibitors of AcrAB-TolC as adjuvants of existing antibiotics and provide novel targets for this urgent undertaking. PMID:27050393

  3. Multidrug Transporters and Alterations in Sterol Biosynthesis Contribute to Azole Antifungal Resistance in Candida parapsilosis.

    PubMed

    Berkow, Elizabeth L; Manigaba, Kayihura; Parker, Josie E; Barker, Katherine S; Kelly, Stephen L; Rogers, P David

    2015-10-01

    While much is known concerning azole resistance in Candida albicans, considerably less is understood about Candida parapsilosis, an emerging species of Candida with clinical relevance. We conducted a comprehensive analysis of azole resistance in a collection of resistant C. parapsilosis clinical isolates in order to determine which genes might play a role in this process within this species. We examined the relative expression of the putative drug transporter genes CDR1 and MDR1 and that of ERG11. In isolates overexpressing these genes, we sequenced the genes encoding their presumed transcriptional regulators, TAC1, MRR1, and UPC2, respectively. We also sequenced the sterol biosynthesis genes ERG3 and ERG11 in these isolates to find mutations that might contribute to this phenotype in this Candida species. Our findings demonstrate that the putative drug transporters Cdr1 and Mdr1 contribute directly to azole resistance and suggest that their overexpression is due to activating mutations in the genes encoding their transcriptional regulators. We also observed that the Y132F substitution in ERG11 is the only substitution occurring exclusively among azole-resistant isolates, and we correlated this with specific changes in sterol biosynthesis. Finally, sterol analysis of these isolates suggests that other changes in sterol biosynthesis may contribute to azole resistance in C. parapsilosis. PMID:26169412

  4. Multidrug Transporters and Alterations in Sterol Biosynthesis Contribute to Azole Antifungal Resistance in Candida parapsilosis

    PubMed Central

    Berkow, Elizabeth L.; Manigaba, Kayihura; Parker, Josie E.; Barker, Katherine S.; Kelly, Stephen L.

    2015-01-01

    While much is known concerning azole resistance in Candida albicans, considerably less is understood about Candida parapsilosis, an emerging species of Candida with clinical relevance. We conducted a comprehensive analysis of azole resistance in a collection of resistant C. parapsilosis clinical isolates in order to determine which genes might play a role in this process within this species. We examined the relative expression of the putative drug transporter genes CDR1 and MDR1 and that of ERG11. In isolates overexpressing these genes, we sequenced the genes encoding their presumed transcriptional regulators, TAC1, MRR1, and UPC2, respectively. We also sequenced the sterol biosynthesis genes ERG3 and ERG11 in these isolates to find mutations that might contribute to this phenotype in this Candida species. Our findings demonstrate that the putative drug transporters Cdr1 and Mdr1 contribute directly to azole resistance and suggest that their overexpression is due to activating mutations in the genes encoding their transcriptional regulators. We also observed that the Y132F substitution in ERG11 is the only substitution occurring exclusively among azole-resistant isolates, and we correlated this with specific changes in sterol biosynthesis. Finally, sterol analysis of these isolates suggests that other changes in sterol biosynthesis may contribute to azole resistance in C. parapsilosis. PMID:26169412

  5. Skeletal muscle amino acid transporter expression is increased in young and older adults following resistance exercise

    PubMed Central

    Fry, Christopher S.; Glynn, Erin L.; Timmerman, Kyle L.; Dickinson, Jared M.; Walker, Dillon K.; Gundermann, David M.; Volpi, Elena; Rasmussen, Blake B.

    2011-01-01

    Amino acid transporters and mammalian target of rapamycin complex 1 (mTORC1) signaling are important contributors to muscle protein anabolism. Aging is associated with reduced mTORC1 signaling following resistance exercise, but the role of amino acid transporters is unknown. Young (n = 13; 28 ± 2 yr) and older (n = 13; 68 ± 2 yr) subjects performed a bout of resistance exercise. Skeletal muscle biopsies (vastus lateralis) were obtained at basal and 3, 6, and 24 h postexercise and were analyzed for amino acid transporter mRNA and protein expression and regulators of amino acid transporter transcription utilizing real-time PCR and Western blotting. We found that basal amino acid transporter expression was similar in young and older adults (P > 0.05). Exercise increased L-type amino acid transporter 1/solute-linked carrier (SLC) 7A5, CD98/SLC3A2, sodium-coupled neutral amino acid transporter 2/SLC38A2, proton-assisted amino acid transporter 1/SLC36A1, and cationic amino acid transporter 1/SLC7A1 mRNA expression in both young and older adults (P < 0.05). L-type amino acid transporter 1 and CD98 protein increased only in younger adults (P < 0.05). eukaryotic initiation factor 2 α-subunit (S52) increased similarly in young and older adults postexercise (P < 0.05). Ribosomal protein S6 (S240/244) and activating transcription factor 4 nuclear protein expression tended to be higher in the young, while nuclear signal transducer and activator of transcription 3 (STAT3) (Y705) was higher in the older subjects postexercise (P < 0.05). These results suggest that the rapid upregulation of amino acid transporter expression following resistance exercise may be regulated differently between the age groups, but involves a combination of mTORC1, activating transcription factor 4, eukaryotic initiation factor 2 α-subunit, and STAT3. We propose an increase in amino acid transporter expression may contribute to enhanced amino acid sensitivity following exercise in young and older

  6. Distribution and Physiology of ABC-Type Transporters Contributing to Multidrug Resistance in Bacteria

    PubMed Central

    Lubelski, Jacek; Konings, Wil N.; Driessen, Arnold J. M.

    2007-01-01

    Summary: Membrane proteins responsible for the active efflux of structurally and functionally unrelated drugs were first characterized in higher eukaryotes. To date, a vast number of transporters contributing to multidrug resistance (MDR transporters) have been reported for a large variety of organisms. Predictions about the functions of genes in the growing number of sequenced genomes indicate that MDR transporters are ubiquitous in nature. The majority of described MDR transporters in bacteria use ion motive force, while only a few systems have been shown to rely on ATP hydrolysis. However, recent reports on MDR proteins from gram-positive organisms, as well as genome analysis, indicate that the role of ABC-type MDR transporters in bacterial drug resistance might be underestimated. Detailed structural and mechanistic analyses of these proteins can help to understand their molecular mode of action and may eventually lead to the development of new strategies to counteract their actions, thereby increasing the effectiveness of drug-based therapies. This review focuses on recent advances in the analysis of ABC-type MDR transporters in bacteria. PMID:17804667

  7. Time-lapse resistivity investigations for imaging saltwater transport in glaciofluvial deposits

    NASA Astrophysics Data System (ADS)

    Leroux, Virginie; Dahlin, Torleif

    2006-01-01

    Five intersecting resistivity sections have been measured in glaciofluvial deposits hosting an aquifer of regional importance situated along a heavy traffic highway in Sweden. The winter salt spreading has caused a regular salinity increase through the years. For imaging the transport of saltwater in the aquifer, the sections were measured exactly in the same location before and after winter, and interpreted using a time-lapse inverse procedure. Some auger drilling and RCPT data were available for correlation. After winter, the resistivity had generally decreased under the water table and increased above it. The decrease in resistivity in the saturated zone is interpreted as a plume of more saline groundwater created by de-icing salt from the road. The increase in the upper layer can be explained by changes in temperature and soil moisture. The study shows that time-lapse resistivity investigations has potential for imaging hydraulic pathways in complex hydrogeological environments.

  8. Tangeretin, a citrus pentamethoxyflavone, antagonizes ABCB1-mediated multidrug resistance by inhibiting its transport function.

    PubMed

    Feng, Sen-Ling; Yuan, Zhong-Wen; Yao, Xiao-Jun; Ma, Wen-Zhe; Liu, Liang; Liu, Zhong-Qiu; Xie, Ying

    2016-08-01

    Multidrug resistance (MDR) and tumor metastasis are the main causes of chemotherapeutic treatment failure and mortality in cancer patients. In this study, at achievable nontoxic plasma concentrations, citrus flavonoid tangeretin has been shown to reverse ABCB1-mediated cancer resistance to a variety of chemotherapeutic agents effectively. Co-treatment of cells with tangeretin and paclitaxel activated apoptosis as well as arrested cell cycle at G2/M-phase. Tangeretin profoundly inhibited the ABCB1 transporter activity since it significantly increased the intracellular accumulation of doxorubicin, and flutax-2 in A2780/T cells and decreased the efflux of ABCB1 substrates in Caco2 cells without altering the expression of ABCB1. Moreover, it stimulated the ATPase activity and inhibited verapamil-stimulated ATPase activity in a concentration-dependent manner, indicating a direct interaction with the transporter. The molecular docking results indicated a favorable binding of tangeretin with the transmemberane region site 1 of homology modeled ABCB1 transporter. The overall results demonstrated that tangeretin could sensitize ABCB1-overexpressing cancer cells to chemotherapeutical agents by directly inhibiting ABCB1 transporter function, which encouraged further animal and clinical studies in the treatment of resistant cancers. PMID:27058921

  9. Identification of a Novel Membrane Transporter Mediating Resistance to Organic Arsenic in Campylobacter jejuni

    PubMed Central

    Shen, Zhangqi; Luangtongkum, Taradon; Qiang, Zhiyi; Jeon, Byeonghwa; Wang, Liping

    2014-01-01

    Although bacterial mechanisms involved in the resistance to inorganic arsenic are well understood, the molecular basis for organic arsenic resistance has not been described. Campylobacter jejuni, a major food-borne pathogen causing gastroenteritis in humans, is highly prevalent in poultry and is reportedly resistant to the arsenic compound roxarsone (4-hydroxy-3-nitrobenzenearsonic acid), which has been used as a feed additive in the poultry industry for growth promotion. In this study, we report the identification of a novel membrane transporter (named ArsP) that contributes to organic arsenic resistance in Campylobacter. ArsP is predicted to be a membrane permease containing eight transmembrane helices, distinct from other known arsenic transporters. Analysis of multiple C. jejuni isolates from various animal species revealed that the presence of an intact arsP gene is associated with elevated resistance to roxarsone. In addition, inactivation of arsP in C. jejuni resulted in 4- and 8-fold reductions in the MICs of roxarsone and nitarsone, respectively, compared to that for the wild-type strain. Furthermore, cloning of arsP into a C. jejuni strain lacking a functional arsP gene led to 16- and 64-fold increases in the MICs of roxarsone and nitarsone, respectively. Neither mutation nor overexpression of arsP affected the MICs of inorganic arsenic, including arsenite and arsenate, in Campylobacter. Moreover, acquisition of arsP in NCTC 11168 led to accumulation of less roxarsone than the wild-type strain lacking arsP. Together, these results indicate that ArsP functions as an efflux transporter specific for extrusion of organic arsenic and contributes to the resistance to these compounds in C. jejuni. PMID:24419344

  10. Reemergence of chloroquine (CQ) analogs as multi-targeting antimalarial agents: a review.

    PubMed

    Mushtaque, Md; Shahjahan

    2015-01-27

    Amongst several communicable diseases (CDs), malaria is one of the deadliest parasitic disease all over the world, particularly in African and Asian countries. To curb this menace, numbers of antimalarial agents are being sold as over the counter (OTC) drugs. Chloroquine (CQ) is one of them and is one of the oldest, cheapest, and easily available synthetic agents used to curb malaria. Unfortunately, after the reports of CQ-resistance against different strains of malarial parasite strains worldwide, scientist are continuously modifying the core structure of CQ to get an efficient drug. Interestingly, several new drugs have been emerged in due course having unique and enhanced properties (like dual stage inhibitors, resistance reversing ability etc.) and are ready to enter into the clinical trial. In this course, some new agents have also been discovered which are; though inactive against CQS strain, highly active against CQR strains. The present article describes the role of modification of the core structure of CQ and its effects on the biological activities. Moreover, the attempt has also been made to predict the future prospects of such drugs to reemerge as antimalarial agents. PMID:25461328

  11. Interaction of gatifloxacin with efflux transporters: a possible mechanism for drug resistance

    PubMed Central

    Kwatra, Deep; Vadlapatla, Ramya Krishna; Vadlapudi, Aswani Dutt; Pal, Dhananjay; Mitra, Ashim K.

    2010-01-01

    The purpose of the study is to screen the interactions of fourth generation fluoroquinolone-gatifloxacin with efflux pumps i.e. P-gp, MRP2 and BCRP. Mechanism of gatifloxacin interaction with efflux transporters may explain its acquired resistance. Such clarification may lead to the development of strategies to overcome efflux and enhance its bioavailability at target site. This process will aid in the reduction of dose volume, further eliminating the chances of systemic toxicity from topical gatifloxacin eye drops. MDCK cell lines transfected with the targeted efflux transporters were used for this study. [14C] Erythromycin was selected as a model substrate for P-gp and MRP2 whereas Hoechst 33342 was employed as a substrate for BCRP. Uptake and transport studies of these substrates were performed in the presence of gatifloxacin to delineate its interaction with efflux transporters. Further the efflux ratio in the presence of gatifloxacin was calculated from bidirectional transport studies. The concentration of [14C] erythromycin and Hoechst 33342 were measured using scintillation counter and fluorescence plate reader respectively. A concentration dependent inhibition effect in the presence of gatifloxacin was revealed on [14C] erythromycin uptake. The efflux ratio (BL-AP/AP-BL) of substrates was found to approach unity at higher gatifloxacin concentrations. Increased concentration of gatifloxacin did not elevate uptake of Hoechst 33342. All these studies were validated with known inhibitors as positive control. Uptake and transport studies support the hypothesis that gatifloxacin is a substrate for P-gp, MRP2 but not for BCRP. Possible interactions of gatifloxacin with P-gp and MRP2 may be a possible mechanism for acquired resistance of gatifloxacin. This information can be further extended to design prodrugs or formulations in order to prevent development of acquired resistance and improve therapeutic efficacy with its reduction in side effects. PMID:20573570

  12. Use of alveolar cell monolayers of varying electrical resistance to measure pulmonary peptide transport.

    PubMed

    Dodoo, A N; Bansal, S S; Barlow, D J; Bennet, F; Hider, R C; Lansley, A B; Lawrence, M J; Marriott, C

    2000-02-01

    The apparent permeability coefficient (P(app)) of two fluorescently tagged model hydrophilic peptides, acXASNH(2) and acXAS(GAS)(7)NH(2), and (14)C-mannitol across monolayers of cultured rat alveolar epithelial cells of varying transepithelial electrical resistance (TER) has been examined. In line with their design features, the peptides were not degraded under the conditions of the test. Furthermore, no concentration dependence of transport of the tripeptide acXASNH(2) was observed over the concentration range studied, nor was any directional transport seen for either of the model peptides, indicating that under the conditions of the test they were not substrates for any transporters or efflux pumps. From the hydrophilic nature of the peptides (as assessed by their log P), and their inverse dependence of transport with molecular weight and TER, it was assumed that the peptides were transported across the cell monolayer passively via the paracellular route. The observed P(app) for the transport of (14)C-mannitol and the peptides across rat alveolar epithelial cell monolayers were found to be inversely (though not linearly) related to the measured TER and could be well-modeled assuming the presence of two populations of "pores" in the cell monolayer, namely, cylindrical pores of diameter 1.5 nm and large pores of diameter 20 nm. The relative populations of the two types of pores varied with the TER of the monolayer, with the number of large pores decreasing with an increase in TER (and the number of small pores taken as fixed). These results suggest that if the cell monolayer is well characterized with respect to the passage of a range of probe molecules across monolayers of varying electrical resistance, it should be possible to predict the P(app) of any hydrophilic peptide or drug crossing the membrane by the paracellular route at any desired TER using a monolayer of any electrical resistance, above a minimum value. PMID:10688751

  13. Contributions of Aspergillus fumigatus ATP-Binding Cassette Transporter Proteins to Drug Resistance and Virulence

    PubMed Central

    Paul, Sanjoy; Diekema, Daniel

    2013-01-01

    In yeast cells such as those of Saccharomyces cerevisiae, expression of ATP-binding cassette (ABC) transporter proteins has been found to be increased and correlates with a concomitant elevation in azole drug resistance. In this study, we investigated the roles of two Aspergillus fumigatus proteins that share high sequence similarity with S. cerevisiae Pdr5, an ABC transporter protein that is commonly overproduced in azole-resistant isolates in this yeast. The two A. fumigatus genes encoding the ABC transporters sharing the highest sequence similarity to S. cerevisiae Pdr5 are called abcA and abcB here. We constructed deletion alleles of these two different ABC transporter-encoding genes in three different strains of A. fumigatus. Loss of abcB invariably elicited increased azole susceptibility, while abcA disruption alleles had variable phenotypes. Specific antibodies were raised to both AbcA and AbcB proteins. These antisera allowed detection of AbcB in wild-type cells, while AbcA could be visualized only when overproduced from the hspA promoter in A. fumigatus. Overproduction of AbcA also yielded increased azole resistance. Green fluorescent protein fusions were used to provide evidence that both AbcA and AbcB are localized to the plasma membrane in A. fumigatus. Promoter fusions to firefly luciferase suggested that expression of both ABC transporter-encoding genes is inducible by azole challenge. Virulence assays implicated AbcB as a possible factor required for normal pathogenesis. This work provides important new insights into the physiological roles of ABC transporters in this major fungal pathogen. PMID:24123268

  14. MFS transporters of Candida species and their role in clinical drug resistance.

    PubMed

    K Redhu, Archana; Shah, Abdul H; Prasad, Rajendra

    2016-06-01

    ABC (ATP-binding cassette) and MFS (major facilitator superfamily) exporters, belonging to two different superfamilies, are one of the most prominent contributors of multidrug resistance (MDR) in yeast. While the role of ABC efflux pump proteins in the development of MDR is well documented, the MFS transporters which are also implicated in clinical drug resistance have not received due attention. The MFS superfamily is the largest known family of secondary active membrane carriers, and MFS exporters are capable of transporting a host of substrates ranging from small molecules, including organic and inorganic ions, to complex biomolecules, such as peptide and lipid moieties. A few of the members of the drug/H(+) antiporter family of the MFS superfamily function as multidrug transporters and employ downhill transport of protons to efflux their respective substrates. This review focuses on the recent developments in MFS of Candida and highlights their role in drug transport by using the example of the relatively well characterized promiscuous Mdr1 efflux pump of the pathogenic yeast C. albicans. PMID:27188885

  15. Contact resistance and phase slips in mesoscopic superfluid-atom transport

    NASA Astrophysics Data System (ADS)

    Eckel, S.; Lee, Jeffrey G.; Jendrzejewski, F.; Lobb, C. J.; Campbell, G. K.; Hill, W. T.

    2016-06-01

    We experimentally measure transport of superfluid, bosonic atoms in a mesoscopic system: a small channel connecting two large reservoirs. Starting far from equilibrium (superfluid in a single reservoir), we observe first resistive flow transitioning at a critical current into superflow, characterized by oscillations. We reproduce this full evolution with a simple electronic circuit model. We compare our fitted conductance to two different microscopic phenomenological models. We also show that the oscillations are consistent with LC oscillations as estimated by the kinetic inductance and effective capacitance in our system. Our experiment provides an attractive platform to begin to probe the mesoscopic transport properties of a dilute, superfluid, Bose gas.

  16. Transport characteristics of meander and bispiral types resistive fault current limiters

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Nishimoto, M.; Joo, J. H.; Murase, S.

    2008-09-01

    The resistive type fault current limiter based on YBCO thin film with high critical current density was proposed and developed because of its fast recovery characteristics. We have been developing a magnetic field measurement system with hall sensor to study the critical current density distribution or magnetic properties of high- Tc superconductors such as thin film, tape conductor and coated conductors. In this study, the transport current distribution in straight line and U-corner region of meander type resistive fault current limiter using YBCO thin film was investigated experimentally. The both axial and radial self-magnetic field components according to the direct (DC) and alternating (AC) transport currents were measured by two-axis hall probe to estimate the current distribution. And also, the self-magnetic field at the corner of bispiral type fault current limiter was measured by two-axis hall probe with a high spatial resolution to compare with the meander type fault current limiter.

  17. Electrical resistance tomography of unsaturated flow and transport in Yucca Mountain

    SciTech Connect

    Buettner, H M; Bussod, G; Daily, W; Ramirez, A

    1998-12-28

    Electrical Resistance Tomography (ERT), a new geophysical imaging technique, was used to study the movement of a tracer through the test block at the Unsaturated Zone Transport Test (UZTT) at Busted Butte, Nevada. Data were collected four times starting in July and ending in early September, 1998. ERT baseline images show a resistivity structure which is consistent with the known lithology in the rear part of the test block. There appears to be a low resistivity region in the front half of the block, particularly near the bottom. Difference images from August 19 and September 9 show clear and consistent resistivity decreases in the region near injection holes 18, 20, and 21 which can be associated with the injection of conductive water. The images show very little effect in the region around the other injection holes, 23, and 24 through 27 where far less water was injected. Difference images from August 19 and September 9 show resistivity decreases which could be interpreted as water moving down into the block. This is the same region which has an anomalously low resistivity in the baseline image. These results should be considered preliminary, and are subject to further interpretation.

  18. Chloroquine: An Old Drug with New Perspective Against Giardiasis.

    PubMed

    Escobedo, Angel A; Almirall, Pedro; Cimerman, Sérgio; Lalle, Marco; Pacheco, Frank; Acanda, Carlos Z; Sánchez, Niurka

    2015-01-01

    The occurrence of treatment failures to first-line treatment for giardiasis, one of the most widespread although neglected parasitic disease, has long been recognised. Nowadays, it starts to represent a great challenge to clinicians, especially in endemic countries. This requires the introduction of new drug interventions, but the development of novel drugs is a time and money consuming effort with most of the compounds never reaching the market. Consequently, alternative strategies are needed, especially for the treatment of giardiasis. Chloroquine (CQ), a synthetic drug developed as antimalarial agent, has been shown to also exert antigiardial activity. Here, we present a mini-research summarizing results on the treatment of human clinical cases with CQ, going through in vitro research, case report, and case series to human clinical trials, highlighting the benefits and mentioning possible adverse effects. PMID:26365362

  19. Tumor vessel normalization by chloroquine independent of autophagy.

    PubMed

    Maes, Hannelore; Kuchnio, Anna; Peric, Aleksandar; Moens, Stijn; Nys, Kris; De Bock, Katrien; Quaegebeur, Annelies; Schoors, Sandra; Georgiadou, Maria; Wouters, Jasper; Vinckier, Stefan; Vankelecom, Hugo; Garmyn, Marjan; Vion, Anne-Clémence; Radtke, Freddy; Boulanger, Chantal; Gerhardt, Holger; Dejana, Elisabetta; Dewerchin, Mieke; Ghesquière, Bart; Annaert, Wim; Agostinis, Patrizia; Carmeliet, Peter

    2014-08-11

    Chloroquine (CQ) has been evaluated as an autophagy blocker for cancer treatment, but it is unknown if it acts solely by inhibiting cancer cell autophagy. We report that CQ reduced tumor growth but improved the tumor milieu. By normalizing tumor vessel structure and function and increasing perfusion, CQ reduced hypoxia, cancer cell invasion, and metastasis, while improving chemotherapy delivery and response. Inhibiting autophagy in cancer cells or endothelial cells (ECs) failed to induce such effects. CQ's vessel normalization activity relied mainly on alterations of endosomal Notch1 trafficking and signaling in ECs and was abrogated by Notch1 deletion in ECs in vivo. Thus, autophagy-independent vessel normalization by CQ restrains tumor invasion and metastasis while improving chemotherapy, supporting the use of CQ for anticancer treatment. PMID:25117709

  20. [Chloroquine influence on lipid metabolism and selected laboratory parameters].

    PubMed

    Woźniacka, Anna; Lesiak, Aleksandra; Smigielski, Janusz; Sysa-Jedrzejowska, Anna

    2005-01-01

    Systemic lupus erythematosus (SLE) is an autoimmune connective tissue disease with complex pathogenesis, various clinical presentation and chronic course with relapses. Mode of treatment depends on the disease activity and kind of internal organ involvement. In most cases clinical remission could be obtained after antimalarials, nonsteroidal anti-inflammatory drugs, corticosteroids, and photoprotection use. Despite the approved antimalarials therapeutic value, the mechanisms by which they provide benefit in lupus, patients are not fully understood. Literature data indicate that they can influence lipid metabolism. The aim of the performed study was the objective evaluation of the influence of 3-month chloroquine treatment (Arechin, 250 mg/day) on lipid metabolism and selected laboratory parameters. In 34 patients with SLE clinical and laboratory evaluation was performed twice, before and after 3-month treatment. After 3 months significantly lower total cholesterol level was observed (mean value 184.91 mg%, 165.26 mg%, p < 0.001). Also LDL level was evidently lowered (111.27 mg%, 99.25 mg%). Similar tendency was noticed in triglycerides, which level after 3 months decreased from the average 152.38 mg% to 104.97 mg%, p < 0.001. Moreover the lowering of sedimentation rate, increasing hemoglobin level and lengthening coagulation time was perceived. The results of the study indicate the influence of chloroquine on decreasing of the disease activity, its anti-inflammatory properties and mainly the drug impact on lipid metabolism. Not only does antimalarials treatment reduce the risk of atherosclerosis development but it also minimizes corticosteroids side effects, which are considered to be the basic medication in lupus patients. PMID:16541717

  1. Identification and functional characterization of Penicillium marneffei pleiotropic drug resistance transporters ABC1 and ABC2.

    PubMed

    Panapruksachat, Siribun; Iwatani, Shun; Oura, Takahiro; Vanittanakom, Nongnuch; Chindamporn, Ariya; Niimi, Kyoko; Niimi, Masakazu; Lamping, Erwin; Cannon, Richard D; Kajiwara, Susumu

    2016-07-01

    Penicilliosis caused by the dimorphic fungus Penicillium marneffei is an endemic, AIDS-defining illness and, after tuberculosis and cryptococcosis, the third most common opportunistic infection of AIDS patients in tropical Southeast Asia. Untreated, patients have poor prognosis; however, primary amphotericin B treatment followed by prolonged itraconazole prophylaxis is effective. To identify ATP-binding cassette (ABC) transporters that may play a role in potential multidrug resistance of P. marneffei, we identified and classified all 46 P. marneffei ABC transporters from the genome sequence. PmABC1 and PmABC2 were most similar to the archetype Candida albicans multidrug efflux pump gene CDR1. P. marneffei Abc1p (PmAbc1p) was functionally expressed in Saccharomyces cerevisiae, although at rather low levels, and correctly localized to the plasma membrane, causing cells to be fourfold to eightfold more resistant to azoles and many other xenobiotics than untransformed cells. P. marneffei Abc2p (PmAbc2p) was expressed at similarly low levels, but it had no efflux activity and did not properly localize to the plasma membrane. Interestingly, PmAbc1p mislocalized and lost its transport activity when cells were shifted to 37 °C. We conclude that expression of PmAbc1p in S. cerevisiae confers resistance to several xenobiotics indicating that PmAbc1p may be a multidrug efflux pump. PMID:26782644

  2. Photosensitized labeling of a functional multidrug transporter in living drug-resistant tumor cells

    SciTech Connect

    Raviv, Y.; Pollard, H.B.; Bruggemann, E.P.; Pastan, I.; Gottesman, M.M. )

    1990-03-05

    A 170,000-Da glycoprotein (P170 multidrug transporter) becomes specifically labeled in multidrug-resistant human KB carcinoma cells by the photolabile lipophilic membrane probe 5-(125I)iodonaphthalene-1-azide ((125I)INA) when photoactivation of the probe is triggered by energy transfer from intracellular doxorubicin or rhodamine 123. In contrast, in drug-sensitive cells, drug-induced specific labeling of membrane proteins with (125I)INA was not observed. Instead, multiple membrane proteins became labeled in a nonspecific manner. This phenomenon of drug-induced specific labeling of P170 by (125I)INA is observed only in living cells, but not in purified membrane vesicles or lysed cells. It is generated by doxorubicin and rhodamine 123, drugs that are chromophores and to which the cells exhibit resistance; but it is not observed with other drugs or dyes. Verapamil, a calcium channel blocker which reverses resistance to doxorubicin, also abolishes doxorubicin-induced specific (125I)INA labeling of P170. These results reveal that a specific interaction between P170 and doxorubicin takes place in living cells and demonstrate that P170 is directly involved in the mechanism of drug resistance in vivo. They also provide a possible means to label functional domains in the multidrug transporter. The results demonstrate that photosensitized (125I)INA labeling is a technique which provides sufficient spatial and time resolution to detect specific intracellular interactions between chromophores and proteins in vivo.

  3. Galanin antagonist increases insulin resistance by reducing glucose transporter 4 effect in adipocytes of rats.

    PubMed

    Guo, Lili; Shi, Mingyi; Zhang, Ling; Li, Guangzhi; Zhang, Lingxiang; Shao, Hu; Fang, Penghua; Ma, Yingping; Li, Jian; Shi, Qiaojia; Sui, Yumei

    2011-08-01

    Seeing that galanin increases animal body weight on the conditions of inhibiting insulin secretion and animals with metabolic disorder of galanin easily suffer from diabetes, we postulate that endogenous galanin is necessary to reduce insulin resistance in adipocytes. To test this hypothesis, we compared four groups of rats to examine whether an increase in galanin secretion stimulated by swimming may reduce insulin resistance. The rats from sedentary and trained drug groups were injected by M35, a galanin antagonist. The rats from trained control and trained drug groups swam after each injection for four weeks. We found that exercise significantly elevated plasma galanin contents and glucose transporter 4 (GLUT4) mRNA levels in adipocytes. Meanwhile, M35 treatment reduced GLUT4 and GLUT4 mRNA levels, and glucose infusing rates in euglycemic-hyperinsulinemic clamp tests. The ratios of GLUT4 concentrations at plasma membranes to total cell membranes in both drug groups were lower compared with each control group, respectively. These observations suggest that endogenous galanin reduces insulin resistance by increasing GLUT4 contents and promoting GLUT4 transportation from intracellular membranes to plasma membranes in adipocytes. Galanin is an important hormone to reduce insulin resistance in rats. PMID:21664358

  4. Effect of resistivity gradient on laser-driven electron transport and ion acceleration

    SciTech Connect

    Zhuo, H. B.; Yang, X. H.; Ma, Y. Y.; Li, X. H.; Zhou, C. T.; Yu, M. Y.

    2013-09-15

    The effect of resistivity gradient on laser-driven electron transport and ion acceleration is investigated using collisional particle-in-cell simulation. The study is motivated by recent proton acceleration experiments [Gizzi et al., Phys. Rev. ST Accel. Beams 14, 011301 (2011)], which showed significant effect of the resistivity gradient in layered targets on the proton angular spread. This effect is reproduced in the present simulations. It is found that resistivity-gradient generation of magnetic fields and inhibition of electron transport is significantly enhanced when the feedback interaction between the magnetic field and the fast-electron current is included. Filamentation of the laser-generated hot electron jets inside the target, considered as the origin of the nonuniform proton patterns observed in the experiments, is clearly suppressed by the resistive magnetic field. As a result, the electrostatic sheath field at the target back surface acquires a relatively smooth profile, which contributes to the superior quality of the proton beams accelerated off layered targets in the experiments.

  5. Nickel resistance in fission yeast associated with the magnesium transport system.

    PubMed

    Sarikaya, Aysegul Topal; Akman, Gokhan; Temizkan, Guler

    2006-02-01

    We isolated and characterized a nickel (Ni2+)-resistant mutant (GA1) of Schizosaccharomyces pombe. This mutant strain displayed resistance to both Ni2+ and Zn2+, but not to Cd2+, Co2+, and Cu2+. The growth rate of GA1 increased proportionally with increasing Mg2+ concentrations until 50 mM Mg2+. The GA1 mutation phenotype suggests a defect in Mg2+ uptake. Sequence analysis of the GA1 open reading frame (ORF) O13779, which is homologous to the prokaryotic and eukaryotic CorA Mg2+ transport systems, revealed a point mutation at codon 153 (ccc to acc) resulting in a Pro153Thr substitution in the N-terminus of the CorA domain. Our results provide novel genetic information about Ni2+ resistance in fission yeast. Specifically, that reducing Mg2+ influx through the CorA Mg2+ transport membrane protein confers Ni2+ resistance in S. pombe. We also report that Ni2+ ion detoxification of the fission yeast is related to histidine metabolism and pH. PMID:16444015

  6. An ABC Transporter Mutation Is Correlated with Insect Resistance to Bacillus thuringiensis Cry1Ac Toxin

    PubMed Central

    Gahan, Linda J.; Pauchet, Yannick; Vogel, Heiko; Heckel, David G.

    2010-01-01

    Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt) are commercially successful in reducing pest damage, yet knowledge of resistance mechanisms that threaten their sustainability is incomplete. Insect resistance to the pore-forming Cry1Ac toxin is correlated with the loss of high-affinity, irreversible binding to the mid-gut membrane, but the genetic factors responsible for this change have been elusive. Mutations in a 12-cadherin-domain protein confer some Cry1Ac resistance but do not block this toxin binding in in vitro assays. We sought to identify mutations in other genes that might be responsible for the loss of binding. We employed a map-based cloning approach using a series of backcrosses with 1,060 progeny to identify a resistance gene in the cotton pest Heliothis virescens that segregated independently from the cadherin mutation. We found an inactivating mutation of the ABC transporter ABCC2 that is genetically linked to Cry1Ac resistance and is correlated with loss of Cry1Ac binding to membrane vesicles. ABC proteins are integral membrane proteins with many functions, including export of toxic molecules from the cell, but have not been implicated in the mode of action of Bt toxins before. The reduction in toxin binding due to the inactivating mutation suggests that ABCC2 is involved in membrane integration of the toxin pore. Our findings suggest that ABC proteins may play a key role in the mode of action of Bt toxins and that ABC protein mutations can confer high levels of resistance that could threaten the continued utilization of Bt–expressing crops. However, such mutations may impose a physiological cost on resistant insects, by reducing export of other toxins such as plant secondary compounds from the cell. This weakness could be exploited to manage this mechanism of Bt resistance in the field. PMID:21187898

  7. An ABC transporter mutation is correlated with insect resistance to Bacillus thuringiensis Cry1Ac toxin.

    PubMed

    Gahan, Linda J; Pauchet, Yannick; Vogel, Heiko; Heckel, David G

    2010-12-01

    Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt) are commercially successful in reducing pest damage, yet knowledge of resistance mechanisms that threaten their sustainability is incomplete. Insect resistance to the pore-forming Cry1Ac toxin is correlated with the loss of high-affinity, irreversible binding to the mid-gut membrane, but the genetic factors responsible for this change have been elusive. Mutations in a 12-cadherin-domain protein confer some Cry1Ac resistance but do not block this toxin binding in in vitro assays. We sought to identify mutations in other genes that might be responsible for the loss of binding. We employed a map-based cloning approach using a series of backcrosses with 1,060 progeny to identify a resistance gene in the cotton pest Heliothis virescens that segregated independently from the cadherin mutation. We found an inactivating mutation of the ABC transporter ABCC2 that is genetically linked to Cry1Ac resistance and is correlated with loss of Cry1Ac binding to membrane vesicles. ABC proteins are integral membrane proteins with many functions, including export of toxic molecules from the cell, but have not been implicated in the mode of action of Bt toxins before. The reduction in toxin binding due to the inactivating mutation suggests that ABCC2 is involved in membrane integration of the toxin pore. Our findings suggest that ABC proteins may play a key role in the mode of action of Bt toxins and that ABC protein mutations can confer high levels of resistance that could threaten the continued utilization of Bt-expressing crops. However, such mutations may impose a physiological cost on resistant insects, by reducing export of other toxins such as plant secondary compounds from the cell. This weakness could be exploited to manage this mechanism of Bt resistance in the field. PMID:21187898

  8. Effect of Target Material on Fast-Electron Transport and Resistive Collimation

    NASA Astrophysics Data System (ADS)

    Chawla, S.; Wei, M. S.; Mishra, R.; Akli, K. U.; Chen, C. D.; McLean, H. S.; Morace, A.; Patel, P. K.; Sawada, H.; Sentoku, Y.; Stephens, R. B.; Beg, F. N.

    2013-01-01

    The effect of target material on fast-electron transport is investigated using a high-intensity (0.7 ps, 1020W/cm2) laser pulse irradiated on multilayered solid Al targets with embedded transport (Au, Mo, Al) and tracer (Cu) layers, backed with millimeter-thick carbon foils to minimize refluxing. We consistently observed a more collimated electron beam (36% average reduction in fast-electron induced Cu Kα spot size) using a high- or mid-Z (Au or Mo) layer compared to Al. All targets showed a similar electron flux level in the central spot of the beam. Two-dimensional collisional particle-in-cell simulations showed formation of strong self-generated resistive magnetic fields in targets with a high-Z transport layer that suppressed the fast-electron beam divergence; the consequent magnetic channels guided the fast electrons to a smaller spot, in good agreement with experiments. These findings indicate that fast-electron transport can be controlled by self-generated resistive magnetic fields and may have important implications to fast ignition.

  9. Hydrophobic Organic Hole Transporters for Improved Moisture Resistance in Metal Halide Perovskite Solar Cells.

    PubMed

    Leijtens, Tomas; Giovenzana, Tommaso; Habisreutinger, Severin N; Tinkham, Jonathan S; Noel, Nakita K; Kamino, Brett A; Sadoughi, Golnaz; Sellinger, Alan; Snaith, Henry J

    2016-03-01

    Solar cells based on organic-inorganic perovskite semiconductor materials have recently made rapid improvements in performance, with the best cells performing at over 20% efficiency. With such rapid progress, questions such as cost and solar cell stability are becoming increasingly important to address if this new technology is to reach commercial deployment. The moisture sensitivity of commonly used organic-inorganic metal halide perovskites has especially raised concerns. Here, we demonstrate that the hygroscopic lithium salt commonly used as a dopant for the hole transport material in perovskite solar cells makes the top layer of the devices hydrophilic and causes the solar cells to rapidly degrade in the presence of moisture. By using novel, low cost, and hydrophobic hole transporters in conjunction with a doping method incorporating a preoxidized salt of the respective hole transporters, we are able to prepare efficient perovskite solar cells with greatly enhanced water resistance. PMID:26859777

  10. The prescribing of chloroquine and hydroxychloroquine by consultant rheumatologists in the UK.

    PubMed

    Kay, E A; Rees, J A; Jayson, M I

    1987-10-01

    A questionnaire on chloroquine and hydroxychloroquine prescribing was circulated nationally to 212 consultant rheumatologists and 119 replies were analysed. Of all patients receiving second-line drugs, 10% were prescribed antimalarials, with hydroxychloroquine being used four times more frequently than chloroquine. Eighty-five per cent of rheumatologists always used the same dose of hydroxychloroquine or chloroquine. Only 5% considered patient's weight in deciding the dose. Fear of ocular toxicity was expressed by many physicians; 54% had experienced corneal deposits; 4% retinopathy and 40% believed cumulative dose determined toxicity. Much confusion existed over the necessity for and frequency of ophthalmological monitoring. Only 56% requested ophthalmological tests before commencing treatment, although 86% monitored the eyes during therapy. Other side-effects were believed to affect 1-10% of patients, with no anticipated difference between doses of 250 mg chloroquine and 400 mg hydroxychloroquine daily. PMID:3664163

  11. Canalicular multispecific organic anion transporter/multidrug resistance protein 2 mediates low-affinity transport of reduced glutathione.

    PubMed Central

    Paulusma, C C; van Geer, M A; Evers, R; Heijn, M; Ottenhoff, R; Borst, P; Oude Elferink, R P

    1999-01-01

    The canalicular multispecific organic anion transporter (cMOAT), a member of the ATP-binding cassette transporter family, mediates the transport of a broad range of non-bile salt organic anions from liver into bile. cMOAT-deficient Wistar rats (TR-) are mutated in the gene encoding cMOAT, leading to defective hepatobiliary transport of a whole range of substrates, including bilirubin glucuronide. These mutants also have impaired hepatobiliary excretion of GSH and, as a result, the bile flow in these animals is reduced. In the present work we demonstrate a role for cMOAT in the excretion of GSH both in vivo and in vitro. Biliary GSH excretion in rats heterozygous for the cMOAT mutation (TR/tr) was decreased to 63% of controls (TR/TR) (114+/-24 versus 181+/-20 nmol/min per kg body weight). Madin-Darby canine kidney (MDCK) II cells stably expressing the human cMOAT protein displayed >10-fold increase in apical GSH excretion compared with wild-type MDCKII cells (141+/-6.1 pmol/min per mg of protein versus 13.2+/-1.3 pmol/min per mg of protein in wild-type MDCKII cells). Similarly, MDCKII cells expressing the human multidrug resistance protein 1 showed a 4-fold increase in GSH excretion across the basolateral membrane. In several independent cMOAT-transfectants, the level of GSH excretion correlated with the expression level of the protein. Furthermore, we have shown, in cMOAT-transfected cells, that GSH is a low-affinity substrate for the transporter and that its excretion is reduced upon ATP depletion. In membrane vesicles isolated from cMOAT-expressing MDCKII cells, ATP-dependent S-(2,4-dinitrophenyl)glutathione uptake is competitively inhibited by high concentrations of GSH (Ki approximately 20 mM). We concluded that cMOAT mediates low-affinity transport of GSH. However, since hepatocellular GSH concentrations are high (5-10 mM), cMOAT might serve an important physiological function in maintenance of bile flow in addition to hepatic GSH turnover. PMID:10024515

  12. Chloroquine has tumor-inhibitory and tumor-promoting effects in triple-negative breast cancer

    PubMed Central

    TUOMELA, JOHANNA; SANDHOLM, JOUKO; KAUPPILA, JOONAS H.; LEHENKARI, PETRI; HARRIS, KEVIN W.; SELANDER, KATRI S.

    2013-01-01

    Toll-like receptor-9 (TLR9) is an intracellular DNA receptor that is widely expressed in breast and other cancers. We previously demonstrated that low tumor TLR9 expression upon diagnosis is associated with significantly shortened disease-specific survival times in patients with triple-negative breast cancer (TNBC). There are no targeted therapies for this subgroup of patients whose prognosis is among the worst in breast cancer. Due to the previously detected in vitro anti-invasive effects of chloroquine in these cell lines, the present study aimed to investigate the in vivo effects of chloroquine against two clinical subtypes of TNBC that differ in TLR9 expression. Chloroquine suppressed matrix metalloproteinase (MMP)-2 and MMP-9 mRNA expression and protein activity, whereas MMP-13 mRNA expression and proteolytic activity were increased. Despite enhancing TLR9 mRNA expression, chloroquine suppressed TLR9 protein expression in vitro. Daily treatment of mice with intraperitoneal (i.p.) chloroquine (80 mg/kg/day) for 22 days, did not inhibit the growth of control siRNA or TLR9 siRNA MDA-MB-231 breast cancer cells. In conclusion, despite the favorable in vitro effects on TNBC invasion and viability, particularly in hypoxic conditions, chloroquine does not prevent the growth of the triple-negative MDA-MB-231 cells with high or low TLR9 expression levels in vivo. This may be explained by the activating effects of chloroquine on MMP-13 expression or by the fact that chloroquine, by suppressing TLR9 expression, permits the activation of currently unknown molecular pathways, which allow the aggressive behavior of TNBC cells with low TLR9 expression in hypoxia. PMID:24273604

  13. Antibiotics, Bacteria, and Antibiotic Resistance Genes: Aerial Transport from Cattle Feed Yards via Particulate Matter

    PubMed Central

    McEachran, Andrew D.; Blackwell, Brett R.; Hanson, J. Delton; Wooten, Kimberly J.; Mayer, Gregory D.; Cox, Stephen B.

    2015-01-01

    Background: Emergence and spread of antibiotic resistance has become a global health threat and is often linked with overuse and misuse of clinical and veterinary chemotherapeutic agents. Modern industrial-scale animal feeding operations rely extensively on veterinary pharmaceuticals, including antibiotics, to augment animal growth. Following excretion, antibiotics are transported through the environment via runoff, leaching, and land application of manure; however, airborne transport from feed yards has not been characterized. Objectives: The goal of this study was to determine the extent to which antibiotics, antibiotic resistance genes (ARG), and ruminant-associated microbes are aerially dispersed via particulate matter (PM) derived from large-scale beef cattle feed yards. Methods: PM was collected downwind and upwind of 10 beef cattle feed yards. After extraction from PM, five veterinary antibiotics were quantified via high-performance liquid chromatography with tandem mass spectrometry, ARG were quantified via targeted quantitative polymerase chain reaction, and microbial community diversity was analyzed via 16S rRNA amplification and sequencing. Results: Airborne PM derived from feed yards facilitated dispersal of several veterinary antibiotics, as well as microbial communities containing ARG. Concentrations of several antibiotics in airborne PM immediately downwind of feed yards ranged from 0.5 to 4.6 μg/g of PM. Microbial communities of PM collected downwind of feed yards were enriched with ruminant-associated taxa and were distinct when compared to upwind PM assemblages. Furthermore, genes encoding resistance to tetracycline antibiotics were significantly more abundant in PM collected downwind of feed yards as compared to upwind. Conclusions: Wind-dispersed PM from feed yards harbors antibiotics, bacteria, and ARGs. Citation: McEachran AD, Blackwell BR, Hanson JD, Wooten KJ, Mayer GD, Cox SB, Smith PN. 2015. Antibiotics, bacteria, and antibiotic

  14. The journey from vitamin D-resistant rickets to the regulation of renal phosphate transport.

    PubMed

    Levine, Barton S; Kleeman, Charles R; Felsenfeld, Arnold J

    2009-11-01

    In 1937, Fuller Albright first described two rare genetic disorders: Vitamin D resistant rickets and polyostotic fibrous dysplasia, now respectively known as X-linked hypophosphatemic rickets (XLH) and the McCune-Albright syndrome. Albright carefully characterized and meticulously analyzed one patient, W.M., with vitamin D-resistant rickets. Albright subsequently reported additional carefully performed balance studies on W.M. In this review, which evaluates the journey from the initial description of vitamin D-resistant rickets (XLH) to the regulation of renal phosphate transport, we (1) trace the timeline of important discoveries in unraveling the pathophysiology of XLH, (2) cite the recognized abnormalities in mineral metabolism in XLH, (3) evaluate factors that may affect parathyroid hormone values in XLH, (4) assess the potential interactions between the phosphate-regulating gene with homology to endopeptidase on the X chromosome and fibroblast growth factor 23 (FGF23) and their resultant effects on renal phosphate transport and vitamin D metabolism, (5) analyze the complex interplay between FGF23 and the factors that regulate FGF23, and (6) discuss the genetic and acquired disorders of hypophosphatemia and hyperphosphatemia in which FGF23 plays a role. Although Albright could not measure parathyroid hormone, he concluded on the basis of his studies that showed calcemic resistance to parathyroid extract in W.M. that hyperparathyroidism was present. Using a conceptual approach, we suggest that a defect in the skeletal response to parathyroid hormone contributes to hyperparathyroidism in XLH. Finally, at the end of the review, abnormalities in renal phosphate transport that are sometimes found in patients with polyostotic fibrous dysplasia are discussed. PMID:19808223

  15. Telatinib reverses chemotherapeutic multidrug resistance mediated by ABCG2 efflux transporter in vitro and in vivo

    PubMed Central

    Sodani, Kamlesh; Patel, Atish; Anreddy, Nagaraju; Singh, Satyakam; Yang, Dong-Hua; Kathawala, Rishil J; Kumar, Priyank; Talele, Tanaji T; Chen, Zhe-Sheng

    2014-01-01

    Multidrug resistance (MDR) is a phenomenon where cancer cells become simultaneously resistant to anticancer drugs with different structures and mechanisms of action. MDR has been shown to be associated with overexpression of ATP-binding cassette (ABC) transporters. Here, we report that telatinib, a small molecule tyrosine kinase inhibitor, enhances the anticancer activity of ABCG2 substrate anticancer drugs by inhibiting ABCG2 efflux transporter activity. Co-incubation of ABCG2-overexpressing drug resistant cell lines with telatinib and ABCG2 substrate anticancer drugs significantly reduced cellular viability, whereas telatinib alone did not significantly affect drug sensitive and drug resistant cell lines. Telatinib at 1 μM did not significantly alter the expression of ABCG2 in ABCG2-overexpressing cell lines. Telatinib at 1 μM significantly enhanced the intracellular accumulation of [3H]-mitoxantrone (MX) in ABCG2-overexpressing cell lines. In addition, telatinib at 1 μM significantly reduced the rate of [3H]-MX efflux from ABCG2-overexpressing cells. Furthermore, telatinib significantly inhibited ABCG2-mediated transport of [3H]-E217βG in ABCG2 overexpressing membrane vesicles. Telatinib stimulated the ATPase activity of ABCG2 in a concentration-dependent manner, indicating that telatinib might be a substrate of ABCG2. Binding interactions of telatinib were found to be in transmembrane region of homology modeled human ABCG2. In addition, telatinib (15 mg/kg) with doxorubicin (1.8 mg/kg) significantly decreased the growth rate and tumor size of ABCG2 overexpressing tumors in a xenograft nude mouse model. These results, provided that they can be translated to humans, suggesting that telatinib, in combination with specific ABCG2 substrate drugs may be useful in treating tumors that overexpress ABCG2. PMID:24565910

  16. Synthesis, Antiplasmodial Activity, and β-Hematin Inhibition of Hydroxypyridone-Chloroquine Hybrids.

    PubMed

    Andayi, Warren A; Egan, Timothy J; Gut, Jiri; Rosenthal, Philip J; Chibale, Kelly

    2013-07-11

    A series of noncytotoxic 4-aminoquinoline-3-hydroxypyridin-4-one hybrids were synthesized on the basis of a synergistic in vitro combination of a precursor N-alkyl-3-hydroxypyridin-4-one with chloroquine (CQ) and tested in vitro against CQ resistant (K1 and W2) and sensitive (3D7) strains of Plasmodium falciparum. In vitro antiplasmodial activity of the precursors was negated by blocking the chelator moiety via complexation with gallium(III) or benzyl protection. None of the precursors inhibited β-hematin formation. Most hybrids were more potent inhibitors of β-hematin formation than CQ, and a correlation between antiplasmodial activity and inhibition of β-hematin formation was observed. Potent hybrids against K1, 3D7, and W2, respectively, were 8c (0.13, 0.004, and 0.1 μM); 8d (0.08, 0.01, and 0.02 μM); and 7g (0.07, 0.03, and 0.08 μM). PMID:24900724

  17. Chloroquine is effective against influenza A virus in vitro but not in vivo

    PubMed Central

    Vigerust, David J.; McCullers, Jonathan A.

    2008-01-01

    Background  Chloroquine is an inexpensive and widely available 9‐aminoquinolone used in the management of malaria. Recently, in vitro assays suggest that chloroquine may have utility in the treatment of several viral infections including influenza. Objectives  We sought to test whether chloroquine is effective against influenza in vivo in relevant animal models. Methods  The effectiveness of chloroquine at preventing or ameliorating influenza following viral challenge was assessed in established mouse and ferret disease models. Results  Although active against influenza viruses in vitro, chloroquine did not prevent the weight loss associated with influenza virus infection in mice after challenge with viruses expressing an H1 or H3 hemagglutinin protein. Similarly, clinical signs and viral replication in the nose of ferrets were not altered by treatment. Conclusions  Although in vitro results were promising, chloroquine was not effective as preventive therapy in vivo in standard mouse and ferret models of influenza virus infection. This dampens enthusiasm for the potential utility of the drug for humans with influenza. PMID:19453426

  18. Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals.

    PubMed

    Wehrer, Markus; Lissner, Heidi; Bloem, Esther; French, Helen; Totsche, Kai Uwe

    2014-01-01

    Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques. PMID:24194415

  19. Development of drift-resistive-inertial ballooning transport model for tokamak edge plasmas

    SciTech Connect

    Rafiq, T.; Bateman, G.; Kritz, A. H.; Pankin, A. Y.

    2010-08-15

    A new model is developed for transport driven by drift-resistive-inertial ballooning modes (DRIBMs) in axisymmetric tokamak plasmas. The model is derived using two-fluid reduced Braginskii equations in a generalized s-{alpha} geometry. The unified theory includes diamagnetic effects, parallel electron and ion dynamics, electron inertia, magnetic perturbations, transverse particle diffusion, gyroviscous stress terms, electron and ion equilibrium temperature gradients, and temperature perturbations. A mixing length approximation is used to compute electron and ion thermal transport as well as particle fluxes from eigenvalues and eigenvectors of the linearized equations. The prediction for the saturation level is obtained by balancing the DRIBM growth rate against the nonlinear ExB convection. The parametric dependence of DRIBMs is investigated in systematic scans over density gradient, electron and ion temperature gradients, magnetic-q, collision frequency, magnetic shear, and Larmor radius. The DRIBM threshold is determined as a function of the collision frequency and the density and temperature gradients. The transition from DRIBM to the toroidal ion temperature gradient (ITG) mode is observed for small density gradients. For steep density gradients, the effect of ITG on DRIBM is found to be stabilizing. The transport seen in the DRIBM is of a scale that is consistent with the observed experimental anomalous transport, suggesting that the DRIBM mode could be the principle agent responsible for edge transport in Ohmic and L-mode discharges.

  20. Inhibition of autophagy of fetal rabbit gonoducts by puromycin, tunicamycin and chloroquin in organ culture.

    PubMed

    Djehiche, B; Segalen, J; Chambon, Y

    1996-02-01

    At the end of ambisexual stage, mullerian or wolffian ducts are programmed to die. Cell degeneration is initialized by an appearance of lysosomes, subsequently involved in invading autophagic vacuoles. In an organ culture assay, performed for 6 days, treatments by puromycin, tunicamycin and chloroquine, known to act on synthesis, transport and activation of lysosomal enzymes, were applied to inhibit the duct regression. Four situations were studied: female genital tract of 17 day post coitum (d.p.c.) cultured with differentiated testis of 19 d.p.c.; male genital ducts of 17 d.p.c. cultured without testis; female and male genital tracts of 17 d.p.c. cultured alone as controls. The stabilization of the mullerian duct cultured with testis and of the wolffian duct cultured without testis was obtained. Ultrastructuraly, the lysosomes were scarce or absent and no autophagic vacuoles were observed. In preventing the formation of lysosomes, it was possible to avoid the duct cell autophagy and to comfirm the existence of a wolffian lysosomal system spontaneously active when testosterone is absent, while a mullerian one spontaneously inactive when AMH is absent. PMID:8907731

  1. A Salmonella protein that is required for resistance to antimicrobial peptides and transport of potassium.

    PubMed Central

    Parra-Lopez, C; Lin, R; Aspedon, A; Groisman, E A

    1994-01-01

    The ability of invading pathogens to proliferate within host tissues requires the capacity to resist the killing effects of a wide variety of host defense molecules. sap mutants of the facultative intracellular parasite Salmonella typhimurium exhibit hypersensitivity to antimicrobial peptides, cannot survive within macrophages in vitro and are attenuated for mouse virulence in vivo. We conducted a molecular genetic analysis of the sapG locus and showed that it encodes a product that is 99% identical to the NAD+ binding protein TrkA, a component of a low-affinity K+ uptake system in Escherichia coli. SapG exhibits similarity with other E. coli proteins implicated in K+ transport including KefC, a glutathione-regulated efflux protein, and Kch, a putative transporter similar to eukaryotic K+ channel proteins, sapG mutants were killed by the antimicrobial peptide protamine in the presence of both high and low K+, indicating that protamine hypersensitivity is not due to K+ starvation. Strains with mutations in sapG and either sapJ or the sapABCDF operon were as susceptible as sapG single mutants, suggesting that the proteins encoded by these loci participate in the same resistance pathway. SapG may modulate the activities of SapABCDF and SapJ to mediate the transport of peptides and potassium. Images PMID:8076592

  2. Seasonal Variations in Antibiotic Resistance Gene Transport in the Almendares River, Havana, Cuba

    PubMed Central

    Knapp, Charles W.; Lima, Lazaro; Olivares-Rieumont, Susana; Bowen, Emma; Werner, David; Graham, David W.

    2012-01-01

    Numerous studies have quantified antibiotic resistance genes (ARG) in rivers and streams around the world, and significant relationships have been shown that relate different pollutant outputs and increased local ARG levels. However, most studies have not considered ambient flow conditions, which can vary dramatically especially in tropical countries. Here, ARG were quantified in water column and sediment samples during the dry- and wet-seasons to assess how seasonal and other factors influence ARG transport down the Almendares River (Havana, Cuba). Eight locations were sampled and stream flow estimated during both seasons; qPCR was used to quantify four tetracycline, two erythromycin, and three beta-lactam resistance genes. ARG concentrations were higher in wet-season versus dry-season samples, which combined with higher flows, indicated much greater ARG transport downstream during the wet-season. However, water column ARG levels were more spatially variable in the dry-season than the wet-season, with the proximity of waste outfalls strongly influencing local ARG levels. Results confirm that dry-season sampling provides a useful picture of the impact of individual waste inputs on local stream ARG levels, whereas the majority of ARGs in this tropical river were transported downstream during the wet-season, possibly due to re-entrainment of ARG from sediments. PMID:23189074

  3. SDS-resistant aggregation of membrane proteins: application to the purification of the vesicular monoamine transporter.

    PubMed Central

    Sagné, C; Isambert, M F; Henry, J P; Gasnier, B

    1996-01-01

    The vesicular monoamine transporter, which catalyses a H+/ monoamine antiport in monoaminergic vesicle membrane, is a very hydrophobic intrinsic membrane protein. After solubilization, this protein was found to have a high tendency to aggregate, as shown by SDS/PAGE, especially when samples were boiled in the classical Laemmli buffer before electrophoresis. This behavior was analysed in some detail. The aggregation was promoted by high temperatures, organic solvents and acidic pH, suggesting that it resulted from the unfolding of structure remaining in SDS. The aggregates were very stable and could be dissociated only by suspension in anhydrous trifluoroacetic acid. This SDS-resistant aggregation behaviour was shared by very few intrinsic proteins of the chromaffin granule membrane. Consequently, a purification procedure was based on this property. A detergent extract of chromaffin granule membranes enriched in monoamine transporter was heated and the aggregates were isolated by size-exclusion HPLC in SDS. The aggregates, containing the transporter, were dissociated in the presence of trifluoroacetic acid and analysed on the same HPLC column. This strategy might be of general interest for the purification of membrane proteins that exhibit SDS-resistant aggregation. PMID:8670158

  4. Prediction of multi-drug resistance transporters using a novel sequence analysis method

    PubMed Central

    McDermott, Jason E.; Bruillard, Paul; Overall, Christopher C.; Gosink, Luke; Lindemann, Stephen R.

    2015-01-01

    There are many examples of groups of proteins that have similar function, but the determinants of functional specificity may be hidden by lack of sequence similarity, or by large groups of similar sequences with different functions. Transporters are one such protein group in that the general function, transport, can be easily inferred from the sequence, but the substrate specificity can be impossible to predict from sequence with current methods. In this paper we describe a linguistic-based approach to identify functional patterns from groups of unaligned protein sequences and its application to predict multi-drug resistance transporters (MDRs) from bacteria. We first show that our method can recreate known patterns from PROSITE for several motifs from unaligned sequences. We then show that the method, MDRpred, can predict MDRs with greater accuracy and positive predictive value than a collection of currently available family-based models from the Pfam database. Finally, we apply MDRpred to a large collection of protein sequences from an environmental microbiome study to make novel predictions about drug resistance in a potential environmental reservoir. PMID:26913187

  5. Influence of low-temperature resistivity on fast electron transport in solids: scaling to fast ignition electron beam parameters

    NASA Astrophysics Data System (ADS)

    McKenna, P.; MacLellan, D. A.; Butler, N. M. H.; Dance, R. J.; Gray, R. J.; Robinson, A. P. L.; Neely, D.; Desjarlais, M. P.

    2015-06-01

    The role of low-temperature electrical resistivity in defining the transport properties of mega-Ampere currents of fast (MeV) electrons in solids is investigated using 3D hybrid particle-in-cell (PIC) simulations. By considering resistivity profiles intermediate to the ordered (lattice) and disordered forms of two example materials, lithium and silicon, it is shown that both the magnitude of the resistivity and the shape of the resistivity-temperature profile at low temperatures strongly affect the self-generated resistive magnetic fields and the onset of resistive instabilities, and thus the overall fast electron beam transport pattern. The scaling of these effects to the giga-Ampere electron currents required for the fast ignition scheme for inertial fusion is also explored.

  6. Fate and transport of tylosin and macrolide-resistance genes following manure applications in tile-drained landscapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of antibiotics in swine production leads to antibiotic-resistance in gastrointestinal bacteria. Application of swine manure to drained agricultural fields introduces elevated levels of antibiotic-resistant bacteria and residual antibiotics. The persistence and transport of these agents are g...

  7. ABCC transporters mediate insect resistance to multiple Bt toxins revealed by bulk segregant analysis

    PubMed Central

    2014-01-01

    Background Relatively recent evidence indicates that ABCC2 transporters play a main role in the mode of action of Bacillus thuringiensis (Bt) Cry1A-type proteins. Mapping of major Cry1A resistance genes has linked resistance to the ABCC2 locus in Heliothis virescens, Plutella xylostella, Trichoplusia ni and Bombyx mori, and mutations in this gene have been found in three of these Bt-resistant strains. Results We have used a colony of Spodoptera exigua (Xen-R) highly resistant to a Bt commercial bioinsecticide to identify regions in the S. exigua genome containing loci for major resistance genes by using bulk segregant analysis (BSA). Results reveal a region containing three genes from the ABCC family (ABBC1, ABBC2 and ABBC3) and a mutation in one of them (ABBC2) as responsible for the resistance of S. exigua to the Bt commercial product and to its key Spodoptera-active ingredients, Cry1Ca. In contrast to all previously described mutations in ABCC2 genes that directly or indirectly affect the extracellular domains of the membrane protein, the ABCC2 mutation found in S. exigua affects an intracellular domain involved in ATP binding. Functional analyses of ABBC2 and ABBC3 support the role of both proteins in the mode of action of Bt toxins in S. exigua. Partial silencing of these genes with dsRNA decreased the susceptibility of wild type larvae to both Cry1Ac and Cry1Ca. In addition, reduction of ABBC2 and ABBC3 expression negatively affected some fitness components and induced up-regulation of arylphorin and repat5, genes that respond to Bt intoxication and that are found constitutively up-regulated in the Xen-R strain. Conclusions The current results show the involvement of different members of the ABCC family in the mode of action of B. thuringiensis proteins and expand the role of the ABCC2 transporter in B. thuringiensis resistance beyond the Cry1A family of proteins to include Cry1Ca. PMID:24912445

  8. A diversity of Antibiotic-resistant Staphylococcus spp. in a Public Transportation System

    PubMed Central

    Yeh, Pamela J.; Simon, Dawn M.; Millar, Jess A.; Alexander, H. Forrest; Franklin, Darleen

    2011-01-01

    Objectives Our goal was to determine the diversity and abundance of Staphylococcus bacteria on different components of a public transportation system in a mid-sized US city (Portland, Oregon) and to examine the level of drug resistance in these bacteria. Methods We collected 70 samples from 2 cm × 4 cm sections from seven different areas on buses and trains in Portland, USA, taking 10 samples from each area. We isolated a subset of 14 suspected Staphylococcus spp. colonies based on phenotype, and constructed a phylogeny from16S rRNA sequences to assist in identification. We used the Kirbye–Bauer disk diffusion method to determine resistance levels to six common antibiotics. Results We found a range of pathogenic Staphylococcus species. The mean bacterial colony counts were 97.1 on bus and train floors, 80.1 in cloth seats, 9.5 on handrails, 8.6 on seats and armrests at bus stops, 3.8 on the underside of seats, 2.2 on windows, and 1.8 on vinyl seats per 8 cm2 sample area. These differences were significant (p < 0.001). Of the 14 isolates sequenced, 11 were staphylococci, and of these, five were resistant to penicillin and ampicillin, while only two displayed intermediate resistance to bacitracin. All 11 isolates were sensitive to trimethoprim-sulfamethoxazole, vancomycin, and tetracycline. Conclusions We found six different strains of Staphylococcus, and while there were varying levels of drug resistance, we did not find extensive levels of multidrug-resistant bacteria, and no S. aureus was found. We found floors and cloth seats to be areas on buses and trains that showed particularly high levels of bacteria. PMID:24159474

  9. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum.

    PubMed

    Ibraheem, Zaid O; Abd Majid, R; Noor, S Mohd; Sedik, H Mohd; Basir, R

    2014-01-01

    Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter) and pfcrt (Plasmodium falciparum chloroquine resistance transporter) which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system) and members of drug metabolite transporter (DMT) family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs. PMID:25506039

  10. Chloroquine Improves Survival and Hematopoietic Recovery After Lethal Low-Dose-Rate Radiation

    SciTech Connect

    Lim Yiting; Hedayati, Mohammad; Merchant, Akil A.; Zhang Yonggang; Yu, Hsiang-Hsuan M.; Kastan, Michael B.; Matsui, William; DeWeese, Theodore L.

    2012-11-01

    Purpose: We have previously shown that the antimalarial agent chloroquine can abrogate the lethal cellular effects of low-dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. Methods and Materials: C57BL/6 mice were irradiated with a total of 12.8 Gy delivered at 9.4 cGy/hour. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 {mu}g per 17 g of body weight, 24 hours and 4 hours before irradiation. Bone marrow cells isolated from tibia, fibula, and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retroorbital injection. Chimerism was assessed by flow cytometry. In vitro methylcellulose colony-forming assay of whole bone marrow cells and fluorescence activated cell sorting analysis of lineage depleted cells were used to assess the effect of chloroquine on progenitor cells. Results: Mice pretreated with chloroquine before radiation exhibited a significantly higher survival rate than did mice treated with radiation alone (80% vs. 31%, p = 0.0026). Chloroquine administration before radiation did not affect the survival of ATM null mice (p = 0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after transplantation (4.2% vs. 0.4%, p = 0.015). Conclusion: Chloroquine administration before radiation had a significant effect on the survival of normal but not ATM null mice, strongly suggesting that the in vivo effect, like the in vitro effect, is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR-irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection

  11. Chloroquine improves survival and hematopoietic recovery following lethal low dose- rate radiation

    PubMed Central

    Lim, Yiting; Hedayati, Mohammad; Merchant, Akil A.; Zhang, Yonggang; Yu, Hsiang-Hsuan M; Kastan, Michael B.; Matsui, William; DeWeese, Theodore L.

    2012-01-01

    Purpose We have previously shown that the anti-malarial agent chloroquine can abrogate the lethal cellular effects of low dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. Methods and Materials C57BL/6 mice were irradiated with total of 12.8 Gy delivered at 9.4 cGy/hr. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 μg per 17 g of body weight, 24 hrs and 4 hrs before irradiation. Bone marrow cells isolated from tibia, fibula and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retro orbital injection. Chimerism was assessed by flow cytometry. In vitro methyl cellulose colony forming assay of whole bone marrow cells as well as FACS analysis of lineage depleted cells was used to assess the effect of chloroquine on progenitor cells. Results Mice pretreated with chloroquine prior to radiation exhibited a significantly higher survival rate compared to mice treated with radiation alone (80 vs.31 percent, p=0.0026). Chloroquine administration prior to radiation did not impact the survival of ATM null mice (p=0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after the transplantation (4.2 percent vs. 0.4 percent, p=0.015). Conclusion Chloroquine administration prior to radiation had a significant effect on the survival of normal but not ATM null mice strongly suggesting that the in vivo effect like the in vitro effect is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection against the

  12. A new homolog of FocA transporters identified in cadmium-resistant Euglena gracilis

    SciTech Connect

    Delomenie, Claudine; Foti, Emilie; Floch, Enora; Diderot, Vimala; Porquet, Dominique; Dupuy, Corinne; Bonaly, Jacqueline . E-mail: Jacqueline.bonaly@u-psud.fr

    2007-06-29

    To better understand the cellular mechanism of stress resistance to various pollutants (cadmium, pentachlorophenol), we undertook a survey of the Euglena gracilis transcriptome by mRNA differential display and cDNA cloning. We performed a real-time RT-PCR analysis upon four selected genes. One of them significantly changed its expression level in response to stress treatments: B25 gene was overexpressed in Cd-resistant cells whereas it was down-regulated in PCP-adapted cells. By Race assays we obtained for B25 a 1093 bp cDNA. The deduced protein was identified as a bacterial formate/nitrite transporter (FocA) homolog and the gene was named EgFth. From all the data, we concluded that EgFth overexpression was related to chronic exposure to cadmium.

  13. The role of coherent vorticity in turbulent transport in resistive drift-wave turbulence

    SciTech Connect

    Bos, W. J. T.; Futatani, S.; Benkadda, S.; Schneider, K.

    2008-07-15

    The coherent vortex extraction method, a wavelet technique for extracting coherent vortices out of turbulent flows, is applied to simulations of resistive drift-wave turbulence in magnetized plasma (Hasegawa-Wakatani system). The aim is to retain only the essential degrees of freedom, responsible for the transport. It is shown that the radial density flux is carried by these coherent modes. In the quasi-hydrodynamic regime, coherent vortices exhibit depletion of the polarization-drift nonlinearity and vorticity strongly dominates strain, in contrast to the quasiadiabatic regime.

  14. Isolation and molecular characterization of methicillin-resistant Staphylococcus aureus from public transport.

    PubMed

    Iwao, Yasuhisa; Yabe, Shizuka; Takano, Tomomi; Higuchi, Wataru; Nishiyama, Akihito; Yamamoto, Tatsuo

    2012-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) not only causes disease in hospitals, but also in the community. The characteristics of MRSA transmission in the environment remain uncertain. In this study, MRSA were isolated from public transport in Tokyo and Niigata, Japan. Of 349 trains examined, eight (2.3%) were positive for MRSA. The MRSA isolated belonged to sequence types (STs) 5, 8, 88, and 89, and included community infection-associated ST8 MRSA (with novel type IV staphylococcal cassette chromosome mec) and the ST5 New York/Japan hospital clone. The data indicate that public transport could contribute to the spread of community-acquired MRSA, and awareness of this mode of transmission is necessary. PMID:22040019

  15. A New ABC Half-Transporter in Leishmania major Is Involved in Resistance to Antimony

    PubMed Central

    Manzano, J. I.; García-Hernández, R.; Castanys, S.

    2013-01-01

    The characterization of ABCI4, a new intracellular ATP-binding cassette (ABC) half-transporter in Leishmania major, is described. We show that ABCI4 is involved in heavy metal export, thereby conferring resistance to Pentostam, to Sb(III), and to As(III) and Cd(II). Parasites overexpressing ABCI4 showed a lower mitochondrial toxic effect of antimony by decreasing reactive oxygen species production and maintained higher values of both the mitochondrial electrochemical potential and total ATP levels with respect to controls. The ABCI4 half-transporter forms homodimers as determined by a coimmunoprecipitation assay. A combination of subcellular localization studies under a confocal microscope and a surface biotinylation assay using parasites expressing green fluorescent protein- and FLAG-tagged ABCI4 suggests that the transporter presents a dual localization in both mitochondria and the plasma membrane. Parasites overexpressing ABCI4 present an increased replication in mouse peritoneal macrophages. We have determined that porphyrins are substrates for ABCI4. Consequently, the overexpression of ABCI4 confers resistance to some toxic porphyrins, such as zinc-protoporphyrin, due to the lower accumulation resulting from a significant efflux, as determined using the fluorescent zinc-mesoporphyrin, a validated heme analog. In addition, ABCI4 has a significant ability to efflux thiol after Sb(III) incubation, thus meaning that ABCI4 could be considered to be a potential thiol-X-pump that is able to recognize metal-conjugated thiols. In summary, we have shown that this new ABC transporter is involved in drug sensitivity to antimony and other compounds by efflux as conjugated thiol complexes. PMID:23716044

  16. Functional Evidence of Multidrug Resistance Transporters (MDR) in Rodent Olfactory Epithelium

    PubMed Central

    Molinas, Adrien; Sicard, Gilles; Jakob, Ingrid

    2012-01-01

    Background P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP1) are membrane transporter proteins which function as efflux pumps at cell membranes and are considered to exert a protective function against the entry of xenobiotics. While evidence for Pgp and MRP transporter activity is reported for olfactory tissue, their possible interaction and participation in the olfactory response has not been investigated. Principal Findings Functional activity of putative MDR transporters was assessed by means of the fluorometric calcein acetoxymethyl ester (calcein-AM) accumulation assay on acute rat and mouse olfactory tissue slices. Calcein-AM uptake was measured as fluorescence intensity changes in the presence of Pgp or MRP specific inhibitors. Epifluorescence microscopy measured time course analysis in the olfactory epithelium revealed significant inhibitor-dependent calcein uptake in the presence of each of the selected inhibitors. Furthermore, intracellular calcein accumulation in olfactory receptor neurons was also significantly increased in the presence of either one of the Pgp or MRP inhibitors. The presence of Pgp or MRP1 encoding genes in the olfactory mucosa of rat and mouse was confirmed by RT-PCR with appropriate pairs of species-specific primers. Both transporters were expressed in both newborn and adult olfactory mucosa of both species. To assess a possible involvement of MDR transporters in the olfactory response, we examined the electrophysiological response to odorants in the presence of the selected MDR inhibitors by recording electroolfactograms (EOG). In both animal species, MRPs inhibitors induced a marked reduction of the EOG magnitude, while Pgp inhibitors had only a minor or no measurable effect. Conclusions The findings suggest that both Pgp and MRP transporters are functional in the olfactory mucosa and in olfactory receptor neurons. Pgp and MRPs may be cellular constituents of olfactory receptor neurons and represent potential

  17. Chloroquine rescues A549 cells from paraquat-induced death.

    PubMed

    Xu, Lingjie; Wang, Zhong

    2016-04-01

    Paraquat (PQ) is a widely used herbicide associated with a high mortality rate, yet, there are no effective treatments for PQ poisoning. PQ may damage alveolar type II cells leading to moderate to severe acute respiratory distress syndrome (ARDS). The present study was undertaken to show that PQ causes alveolar type II (A549) cell death and to evaluate whether chloroquine (CQ) can protect A549 cells against PQ-induced cell death. The results showed that high concentrations of PQ resulted in toxicity, as indicated by a decrease in cell viability. More importantly, for the first time, CQ was found to improve cell viability of PQ treated A549 cells. Moreover, our data demonstrated that CQ increased lysosome-associated membrane protein-1, lysosome-associated membrane protein-2 and light chain-3 expressions, suggesting that the mechanism by which CQ rescues PQ-induced cytotoxicity may be through protection of the lysosomal membrane or up-regulation of autophagy. In conclusion, our study indicates that CQ may be used as a potential drug to rescue PQ-induced ARDS. PMID:26154125

  18. Biphasic activity of chloroquine in human colorectal cancer cells.

    PubMed

    Park, Deokbae; Lee, Youngki

    2014-12-01

    Autophagy is a homeostatic degradation process that is involved in tumor development and normal development. Autophagy is induced in cancer cells in response to chemotherapeutic agents, and inhibition of autophagy results in enhanced cancer cell death or survival. Chloroquine (CQ), an anti-malarial devrepug, is a lysosomotropic agent and is currently used as a potential anticancer agent as well as an autophagy inhibitor. Here, we evaluate the characteristics of these dual activities of CQ using human colorectal cancer cell line HCT15. The results show that CQ inhibited cell viability in dose-and time-dependent manner in the range between 20 to 80 uM, while CQ did not show any antiproliferative activity at 5 and 10 uM. Cotreatment of CQ with antitumor agent NVP-BEZ235, a dual inhibitor of PI3K/mTOR, rescued the cell viability at low concentrations meaning that CQ acted as an autophagy inhibitor, but CQ induced the lethal effect at high concentrations. Acridine orange staining revealed that CQ at high doses induced lysosomal membrane permeabilization (LMP). High doses of CQ produced cellular reactive oxygen species (ROS) and cotreatment of antioxidants, such as NAC and trolox, with high doses of CQ rescued the cell viability. These results suggest that CQ may exert its dual activities, as autophagy inhibitor or LMP inducer, in concentration-dependent manner. PMID:25949192

  19. Photophysical properties and photobiological behavior of amodiaquine, primaquine and chloroquine.

    PubMed

    Viola, Giampietro; Salvador, Alessia; Cecconet, Laura; Basso, Giuseppe; Vedaldi, Daniela; Dall'Acqua, Francesco; Aloisi, Gian Gaetano; Amelia, Matteo; Barbafina, Arianna; Latterini, Loredana; Elisei, Fausto

    2007-01-01

    This article describes the results of a coupled photophysical and photobiological study aimed at understanding the phototoxicity mechanism of the antimalarial drugs amodiaquine (AQ), primaquine (PQ) and chloroquine (CQ). Photophysical experiments were carried out in aqueous solutions by steady-state and time-resolved spectrometric techniques to obtain information on the different decay pathways of the excited states of the drugs and on the transient species formed upon laser irradiation. The results showed that all three drugs possess very low fluorescence quantum yields (10(-2)-10(-4)). Laser flash photolysis experiments proved the occurrence of photoionization processes leading to the formation of a radical cation in all three systems. In the case of AQ the lowest triplet state was also detected. Together with the photophysical properties the photobiological properties of the antimalarial drugs were investigated under UV irradiation, on various biological targets through a series of in vitro assays. Phototoxicity on mouse 3T3 fibroblast and human keratinocyte cell lines NCTC-2544 was detected for PQ and CQ but not for AQ. In particular, PQ- and CQ-induced apoptosis was revealed by the externalization of phosphatidylserine. Furthermore, upon UV irradiation, the drugs caused significant variations of the mitochondrial potential (Deltapsi(mt)) measured by flow cytometry. The photodamages produced by the drugs were also evaluated on proteins, lipids and DNA. The combined approaches were useful in understanding the mechanism of phototoxicity induced by these antimalarial drugs. PMID:18028216

  20. Chloroquine and Hydroxychloroquine Increase Retinal Pigment Epithelial Layer Permeability.

    PubMed

    Korthagen, Nicoline M; Bastiaans, Jeroen; van Meurs, Jan C; van Bilsen, Kiki; van Hagen, P Martin; Dik, Willem A

    2015-07-01

    Antimalarials chloroquine (CQ) and hydroxychloroquine (HCQ) are widely used as antiinflammatory drugs, but side effects include retinopathy and vision loss. The objective of this study was to examine the effect of CQ and HCQ on the barrier integrity of retinal pigment epithelial (RPE) cell monolayers in vitro. Permeability of ARPE-19 cell monolayers was determined using Fluorescein isothiocyanate (FITC)-labeled dextran. The influence of CQ and HCQ on cell death and the expression tight junction molecules was examined. CQ and HCQ significantly increased ARPE-19 monolayer permeability after 3 and 18 h, respectively, and enhanced mRNA levels for claudin-1 and occludin. Cytotoxicity was only observed after 18 h exposure. Thus, CQ and HCQ rapidly enhance RPE barrier permeability in vitro, independent of cytotoxicity or loss of zonula occludens-1, claudin-1, and occludin expression. Our findings suggest that CQ/HCQ-induced permeability of the RPE layer may contribute to blood-retinal barrier breakdown in case of CQ/HCQ-induced retinopathy. PMID:25752684

  1. The ubiquitination of serotonin transporter in lymphoblasts derived from fluvoxamine-resistant depression patients.

    PubMed

    Mouri, Akihiro; Ikeda, Masashi; Koseki, Takenao; Iwata, Nakao; Nabeshima, Toshitaka

    2016-03-23

    There is insufficient serotonergic neuronal function in the pathophysiology of major depressive disorder (MDD). Serotonin transporter (SERT) plays a critical role in terminating the function of serotoninergic neurons. SERT is linked to vulnerability to MDD and is an important target for antidepressants. The expression of SERT in lymphocytes and platelets is associated with their expression in central nervous system. Most of the clinical studies that have analyzed the role of SERT in depression have focused on absolute expression of SERT in the brain or peripheral tissue. Our study has shown that the SERT protein is ubiquitinated, which has been implicated through the SERT stability and depressive behaviors in mice. In our study, we have used lymphoblasts derived from the peripheral blood lymphocytes to quantitatively examine SERT protein expression and ubiquitination in fluvoxamine-responsive and fluvoxamine-resistant MDD patients. We found that the protein levels of SERT were higher in the fluvoxamine-resistant MDD patients. Ubiquitinated protein levels of SERT were lower in the fluvoxamine-resistant MDD patients. The proteasome inhibitor failed to increase the protein levels of SERT in both fluvoxamine-responsive and fluvoxamine-resistant MDD patients. In sum, these findings suggest that the downregulation of the ubiquitination of SERT protein induces insufficient degradation of SERT by proteasome, which resulted in the upregulation of SERT protein in fluvoxamine-resistant MDD patients. Although further studies with various populations will be required to generalize results, SERT protein expression, ubiquitination, and the responsiveness of SERT expression to proteasome inhibitor are potential biomarkers for the diagnosis of MDD and antidepressant efficacy. PMID:26845564

  2. A Computational Approach towards the Understanding of Plasmodium falciparum Multidrug Resistance Protein 1

    PubMed Central

    Patel, Saumya K.; Prasanth Kumar, Sivakumar; Highland, Hyacinth N.; Jasrai, Yogesh T.; Pandya, Himanshu A.; Desai, Ketaki R.

    2013-01-01

    The emergence of drug resistance in Plasmodium falciparum tremendously affected the chemotherapy worldwide while the intense distribution of chloroquine-resistant strains in most of the endemic areas added more complications in the treatment of malaria. The situation has even worsened by the lack of molecular mechanism to understand the resistance conferred by Plasmodia species. Recent studies have suggested the association of antimalarial resistance with P. falciparum multidrug resistance protein 1 (PfMDR1), an ATP-binding cassette (ABC) transporter and a homologue of human P-glycoprotein 1 (P-gp1). The present study deals about the development of PfMDR1 computational model and the model of substrate transport across PfMDR1 with insights derived from conformations relative to inward- and outward-facing topologies that switch on/off the transportation system. Comparison of ATP docked positions and its structural motif binding properties were found to be similar among other ATPases, and thereby contributes to NBD domains dimerization, a unique structural agreement noticed in Mus musculus Pgp and Escherichia coli MDR transporter homolog (MsbA). The interaction of leading antimalarials and phytochemicals within the active pocket of both wild-type and mutant-type PfMDR1 demonstrated the mode of binding and provided insights of less binding affinity thereby contributing to parasite's resistance mechanism. PMID:25937947

  3. A Computational Approach towards the Understanding of Plasmodium falciparum Multidrug Resistance Protein 1.

    PubMed

    Patel, Saumya K; George, Linz-Buoy; Prasanth Kumar, Sivakumar; Highland, Hyacinth N; Jasrai, Yogesh T; Pandya, Himanshu A; Desai, Ketaki R

    2013-01-01

    The emergence of drug resistance in Plasmodium falciparum tremendously affected the chemotherapy worldwide while the intense distribution of chloroquine-resistant strains in most of the endemic areas added more complications in the treatment of malaria. The situation has even worsened by the lack of molecular mechanism to understand the resistance conferred by Plasmodia species. Recent studies have suggested the association of antimalarial resistance with P. falciparum multidrug resistance protein 1 (PfMDR1), an ATP-binding cassette (ABC) transporter and a homologue of human P-glycoprotein 1 (P-gp1). The present study deals about the development of PfMDR1 computational model and the model of substrate transport across PfMDR1 with insights derived from conformations relative to inward- and outward-facing topologies that switch on/off the transportation system. Comparison of ATP docked positions and its structural motif binding properties were found to be similar among other ATPases, and thereby contributes to NBD domains dimerization, a unique structural agreement noticed in Mus musculus Pgp and Escherichia coli MDR transporter homolog (MsbA). The interaction of leading antimalarials and phytochemicals within the active pocket of both wild-type and mutant-type PfMDR1 demonstrated the mode of binding and provided insights of less binding affinity thereby contributing to parasite's resistance mechanism. PMID:25937947

  4. Gas production and transport during bench-scale electrical resistance heating of water and trichloroethene

    NASA Astrophysics Data System (ADS)

    Hegele, P. R.; Mumford, K. G.

    2014-09-01

    The effective remediation of chlorinated solvent source zones using in situ thermal treatment requires successful capture of gas that is produced. Replicate electrical resistance heating experiments were performed in a thin bench-scale apparatus, where water was boiled and pooled dense non-aqueous phase liquid (DNAPL) trichloroethene (TCE) and water were co-boiled in unconsolidated silica sand. Quantitative light transmission visualization was used to assess gas production and transport mechanisms. In the water boiling experiments, nucleation, growth and coalescence of the gas phase into connected channels were observed at critical gas saturations of Sgc = 0.233 ± 0.017, which allowed for continuous gas transport out of the sand. In experiments containing a colder region above a target heated zone, condensation prevented the formation of steam channels and discrete gas clusters that mobilized into colder regions were trapped soon after discontinuous transport began. In the TCE-water experiments, co-boiling at immiscible fluid interfaces resulted in discontinuous gas transport above the DNAPL pool. Redistribution of DNAPL was also observed above the pool and at the edge of the vapor front that propagated upwards through colder regions. These results suggest that the subsurface should be heated to water boiling temperatures to facilitate gas transport from specific locations of DNAPL to extraction points and reduce the potential for DNAPL redistribution. Decreases in electric current were observed at the onset of gas phase production, which suggests that coupled electrical current and temperature measurements may provide a reliable metric to assess gas phase development.

  5. Energy budgets and resistances to energy transport in sparsely vegetated rangeland

    USGS Publications Warehouse

    Nichols, W.D.

    1992-01-01

    Partitioning available energy between plants and bare soil in sparsely vegetated rangelands will allow hydrologists and others to gain a greater understanding of water use by native vegetation, especially phreatophytes. Standard methods of conducting energy budget studies result in measurements of latent and sensible heat fluxes above the plant canopy which therefore include the energy fluxes from both the canopy and the soil. One-dimensional theoretical numerical models have been proposed recently for the partitioning of energy in sparse crops. Bowen ratio and other micrometeorological data collected over phreatophytes growing in areas of shallow ground water in central Nevada were used to evaluate the feasibility of using these models, which are based on surface and within-canopy aerodynamic resistances, to determine heat and water vapor transport in sparsely vegetated rangelands. The models appear to provide reasonably good estimates of sensible heat flux from the soil and latent heat flux from the canopy. Estimates of latent heat flux from the soil were less satisfactory. Sensible heat flux from the canopy was not well predicted by the present resistance formulations. Also, estimates of total above-canopy fluxes were not satisfactory when using a single value for above-canopy bulk aerodynamic resistance. ?? 1992.

  6. Chloroquine Engages the Immune System to Eradicate Irradiated Breast Tumors in Mice

    SciTech Connect

    Ratikan, Josephine Anna; Sayre, James William

    2013-11-15

    Purpose: This study used chloroquine to direct radiation-induced tumor cell death pathways to harness the antitumor activity of the immune system. Methods and Materials: Chloroquine given immediately after tumor irradiation increased the cure rate of MCaK breast cancer in C3H mice. Chloroquine blocked radiation-induced autophagy and drove MCaK cells into a more rapid apoptotic and more immunogenic form of cell death. Results: Chloroquine treatment made irradiated tumor vaccines superior at inducing strong interferon gamma-associated immune responses in vivo and protecting mice from further tumor challenge. In vitro, chloroquine slowed antigen uptake and degradation by dendritic cells, although T-cell stimulation was unaffected. Conclusions: This study illustrates a novel approach to improve the efficacy of breast cancer radiation therapy by blocking endosomal pathways, which enhances radiation-induced cell death within the field and drives antitumor immunity to assist therapeutic cure. The study illuminates and merges seemingly disparate concepts regarding the importance of autophagy in cancer therapy.

  7. Oxidant stress in malaria as probed by stable nitroxide radicals in erythrocytes infected with Plasmodium berghei. The effects of primaquine and chloroquine.

    PubMed

    Deslauriers, R; Butler, K; Smith, I C

    1987-12-10

    Erythrocytes from normal mice and mice infected with the malarial parasite Plasmodium berghei reduce the water-soluble spin probes 2,2,6,6-tetramethylpiperidine-4-hydroxy-N-oxyl (TEMPOL), 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and 2,2,6,6-tetramethylpiperidine-4-keto-N-oxyl (TEMPONE) at similar rates under both air and N2 atmospheres. The ESR signal of the lipid-soluble spin probe 5-doxyl-stearate is stable on incorporation into erythrocytes from normal mice. In contrast, parasitized red cells reduce this nitroxide probe, at a rate which increases with the level of parasitemia. Inhibitors of electron transport such as KCN and NaN3, increase the rate of reduction. We propose that nitroxide reduction occurs via the electron transport chain in the parasite. The antimalarial drug primaquine causes reduction of both water-soluble and lipid-soluble spin probes. This action of primaquine is independent of its ability to release H2O2 from oxyhemoglobin, and is ascribed to the ability of primaquine to accelerate flux through the hexose monophosphate shunt. The increased production of NADPH results in increased rates of reduction of the nitroxide radicals. Methylene blue, which also increases flux through the shunt, is even more effective than primaquine at reducing the nitroxides. Chloroquine has no such effect. Parasitized mice treated with chloroquine six hours prior to ESR measurements show less nitroxide reducing capacity than do untreated mice. Chloroquine is known to decrease flux through the hexose monophosphate shunt. The metabolic influences of the two antimalarial drugs are, thus, quite different. PMID:3315005

  8. PARAQUAT RESISTANT1, a Golgi-Localized Putative Transporter Protein, Is Involved in Intracellular Transport of Paraquat1[C][W

    PubMed Central

    Li, Jianyong; Mu, Jinye; Bai, Jiaoteng; Fu, Fuyou; Zou, Tingting; An, Fengying; Zhang, Jian; Jing, Hongwei; Wang, Qing; Li, Zhen; Yang, Shuhua; Zuo, Jianru

    2013-01-01

    Paraquat is one of the most widely used herbicides worldwide. In green plants, paraquat targets the chloroplast by transferring electrons from photosystem I to molecular oxygen to generate toxic reactive oxygen species, which efficiently induce membrane damage and cell death. A number of paraquat-resistant biotypes of weeds and Arabidopsis (Arabidopsis thaliana) mutants have been identified. The herbicide resistance in Arabidopsis is partly attributed to a reduced uptake of paraquat through plasma membrane-localized transporters. However, the biochemical mechanism of paraquat resistance remains poorly understood. Here, we report the identification and characterization of an Arabidopsis paraquat resistant1 (par1) mutant that shows strong resistance to the herbicide without detectable developmental abnormalities. PAR1 encodes a putative l-type amino acid transporter protein localized to the Golgi apparatus. Compared with the wild-type plants, the par1 mutant plants show similar efficiency of paraquat uptake, suggesting that PAR1 is not directly responsible for the intercellular uptake of paraquat. However, the par1 mutation caused a reduction in the accumulation of paraquat in the chloroplast, suggesting that PAR1 is involved in the intracellular transport of paraquat into the chloroplast. We identified a PAR1-like gene, OsPAR1, in rice (Oryza sativa). Whereas the overexpression of OsPAR1 resulted in hypersensitivity to paraquat, the knockdown of its expression using RNA interference conferred paraquat resistance on the transgenic rice plants. These findings reveal a unique mechanism by which paraquat is actively transported into the chloroplast and also provide a practical approach for genetic manipulations of paraquat resistance in crops. PMID:23471133

  9. Measurement of multiple drug resistance transporter activity in putative cancer stem/progenitor cells.

    PubMed

    Donnenberg, Vera S; Meyer, E Michael; Donnenberg, Albert D

    2009-01-01

    Multiple drug resistance, mediated by the expression and activity of ABC-transporters, is a major obstacle to antineoplastic therapy. Normal tissue stem cells and their malignant counterparts share MDR transporter activity as a major mechanism of self-protection. Although MDR activity is upregulated in response to substrate chemotherapeutic agents, it is also constitutively expressed on both normal tissue stem cells and a subset of tumor cells prior to the initiation of therapy, representing a built-in obstacle to therapeutic ratio. Constitutive and induced MDR activity can be detected in cellular subsets of disaggregated tissues, using the fluorescent substrates Rhodamine 123 and Hoechst 33342 for ABCB1 (also known as P-gp and MDR1) and ABCG2 (BCRP1). In this chapter, we will describe the complete procedure for the detection of MDR activity, including: (1) Preparing single-cell suspensions from tumor and normal tissue specimens; (2) An efficient method to perform cell surface marker staining on large numbers of cells; (3) Flow cytometer setup and controls; (4) Simultaneous measurement of Hoechst 33342 and Rhodamine123 transport; and (5) Data acquisition and analysis. PMID:19582433

  10. Characterization of multidrug resistance P-glycoprotein transport function with an organotechnetium cation

    SciTech Connect

    Piwnica-Worms, D.; Vallabhaneni, V.R.; Kronauge, J.F.

    1995-09-26

    Multidrug resistance (MDR) in mammalian cells and tumors is associated with overexpression of an {approximately}170 integral membrane efflux transporter, the MDR1 P-glycoprotein. Hexakis(2-methoxyisobutyl isonitrile) technetium(I) (Tc-SESTAMIBI), a {gamma}-emitting lipophilic cationic metallopharmaceutical, has recently been shown to be a P-glycoprotein transport substrate. Exploiting the negligible lipid membrane adsorption properties of this organometallic substrate, we studied the transport kinetics, pharmacology, drug binding, and modulation of P-glycoprotein in cell preparations derived from a variety of species and selection strategies, including SW-1573, V79, Alex, and CHO drug-sensitive cells and in 77A, LZ-8, and Alex/A.5 MDR cells. Rapid cell accumulation (T{sub 1/2} {approx} 6 min) of the agent to a steady state was observed which was inversely proportional to immunodetectable levels of P-glycoprotein. Many MDR cytotoxic agents inhibited P-glycoprotein-mediated Tc-SESTAMIBI efflux, thereby enhancing organometallic cation accumulation. 70 refs., 7 figs., 2 tabs.

  11. 'Metal'-like transport in high-resistance, high aspect ratio two-dimensional electron gases.

    PubMed

    Backes, Dirk; Hall, Richard; Pepper, Michael; Beere, Harvey; Ritchie, David; Narayan, Vijay

    2016-01-13

    We investigate the striking absence of strong localisation observed in mesoscopic two-dimensional electron gases (2DEGs) (Baenninger et al 2008 Phys. Rev. Lett. 100 016805, Backes et al 2015 arXiv:1505.03444) even when their resistivity [Formula: see text]. In particular, we try to understand whether this phenomenon originates in quantum many-body effects, or simply percolative transport through a network of electron puddles. To test the latter scenario, we measure the low temperature (low-T) transport properties of long and narrow 2DEG devices in which percolation effects should be heavily suppressed in favour of Coulomb blockade. Strikingly we find no indication of Coulomb blockade and that the high-ρ, low-T transport is exactly similar to that previously reported in mesoscopic 2DEGs with different geometries. Remarkably, we are able to induce a 'metal'-insulator transition (MIT) by applying a perpendicular magnetic field B. We present a picture within which these observations fit into the more conventional framework of the 2D MIT. PMID:26647878

  12. Flow topology, Lagrangian statistics, and transport in resistive drift-wave turbulence

    NASA Astrophysics Data System (ADS)

    Kadoch, B.; Del-Castillo-Negrete, Diego; Bos, W. J. T.; Schneider, K.

    2012-10-01

    Transport is strongly influenced by coherent structures. In particular, trapping in vortices tends to arrest transport and zonal flows can induce large Lagrangian displacements. It is thus of interest to characterize coherent structures from a Lagrangian perspective. For 2-D flows, the Eulerian Weiss criterion provides a tool to partition the flow into topologically different regions: elliptic (vortex dominated), hyperbolic (deformation dominated), and intermediate (turbulent background). In Ref.footnotetextB. Kadoch, D. del-Castillo-Negrete, W.J.T Bos, and K. Schneider, Phys. Rev. E 83, 036314 (2011). we proposed the Lagrangian Weiss criterion (i.e. the Weiss field computed along particle orbits) and applied it to 2-D Navier-Stokes turbulence. Here we apply this criterion to resistive drift-wave turbulence. The probability density functions (pdfs) of residence time in the topologically different regions are computed for ensembles of Lagrangian tracers. It is shown that in elliptic and hyperbolic regions the pdfs have algebraically decaying tails. The pdf of residence time in elliptic regions is proposed as a measure of particle trapping, and the relationship with waiting time statistics in continuous time random walk models of anomalous transport is explored.

  13. Dissolved gas exsolution to enhance gas production and transport during bench-scale electrical resistance heating

    NASA Astrophysics Data System (ADS)

    Hegele, P. R.; Mumford, K. G.

    2015-05-01

    Condensation of volatile organic compounds in colder zones can be detrimental to the performance of an in situ thermal treatment application for the remediation of chlorinated solvent source zones. A novel method to increase gas production and limit convective heat loss in more permeable, potentially colder, zones involves the injection and liberation of dissolved gas from solution during heating. Bench-scale electrical resistance heating experiments were performed with a dissolved carbon dioxide and sodium chloride solution to investigate exsolved gas saturations and transport regimes at elevated, but sub-boiling, temperatures. At sub-boiling temperatures, maximum exsolved gas saturations of Sg = 0.12 were attained, and could be sustained when the carbon dioxide solution was injected during heating rather than emplaced prior to heating. This gas saturation was estimated to decrease groundwater relative permeability to krw = 0.64. Discontinuous gas transport was observed above saturations of Sg = 0.07, demonstrating the potential of exsolved CO2 to bridge vertical gas transport through colder zones.

  14. Characterization of Escherichia coli d-Cycloserine Transport and Resistant Mutants

    PubMed Central

    Baisa, Gary; Stabo, Nicholas J.

    2013-01-01

    d-Cycloserine (DCS) is a broad-spectrum antibiotic that inhibits d-alanine ligase and alanine racemase activity. When Escherichia coli K-12 or CFT073 is grown in minimal glucose or glycerol medium, CycA transports DCS into the cell. E. coli K-12 cycA and CFT073 cycA mutant strains display increased DCS resistance when grown in minimal medium. However, the cycA mutants exhibit no change in DCS sensitivity compared to their parental strains when grown in LB (CFT073 and K-12) or human urine (CFT073 only). These data suggest that cycA does not participate in DCS sensitivity when strains are grown in a non-minimal medium. The small RNA GvcB acts as a negative regulator of E. coli K-12 cycA expression when grown in LB. Three E. coli K-12 gcvB mutant strains failed to demonstrate a change in DCS sensitivity when grown in LB. This further suggests a limited role for cycA in DCS sensitivity. To aid in the identification of E. coli genes involved in DCS sensitivity when grown on complex media, the Keio K-12 mutant collection was screened for DCS-resistant strains. dadA, pnp, ubiE, ubiF, ubiG, ubiH, and ubiX mutant strains showed elevated DCS resistance. The phenotypes associated with these mutants were used to further define three previously characterized E. coli DCS-resistant strains (χ316, χ444, and χ453) isolated by Curtiss and colleagues (R. Curtiss, III, L. J. Charamella, C. M. Berg, and P. E. Harris, J. Bacteriol. 90:1238–1250, 1965). A dadA mutation was identified in both χ444 and χ453. In addition, results are presented that indicate for the first time that DCS can antagonize d-amino acid dehydrogenase (DadA) activity. PMID:23316042

  15. Chloroquine sensitizes breast cancer cells to chemotherapy independent of autophagy

    PubMed Central

    Maycotte, Paola; Aryal, Suraj; Cummings, Christopher T; Thorburn, Jacqueline; Morgan, Michael J

    2012-01-01

    Chloroquine (CQ) is a 4-aminoquinoline drug used for the treatment of diverse diseases. It inhibits lysosomal acidification and therefore prevents autophagy by blocking autophagosome fusion and degradation. In cancer treatment, CQ is often used in combination with chemotherapeutic drugs and radiation because it has been shown to enhance the efficacy of tumor cell killing. Since CQ and its derivatives are the only inhibitors of autophagy that are available for use in the clinic, multiple ongoing clinical trials are currently using CQ or hydroxychloroquine (HCQ) for this purpose, either alone, or in combination with other anticancer drugs. Here we show that in the mouse breast cancer cell lines, 67NR and 4T1, autophagy is induced by the DNA damaging agent cisplatin or by drugs that selectively target autophagy regulation, the PtdIns3K inhibitor LY294002, and the mTOR inhibitor rapamycin. In combination with these drugs, CQ sensitized to these treatments, though this effect was more evident with LY294002 and rapamycin treatment. Surprisingly, however, in these experiments CQ sensitization occurred independent of autophagy inhibition, since sensitization was not mimicked by Atg12, Beclin 1 knockdown or bafilomycin treatment, and occurred even in the absence of Atg12. We therefore propose that although CQ might be helpful in combination with cancer therapeutic drugs, its sensitizing effects can occur independently of autophagy inhibition. Consequently, this possibility should be considered in the ongoing clinical trials where CQ or HCQ are used in the treatment of cancer, and caution is warranted when CQ treatment is used in cytotoxic assays in autophagy research. PMID:22252008

  16. Chloroquine sensitizes breast cancer cells to chemotherapy independent of autophagy.

    PubMed

    Maycotte, Paola; Aryal, Suraj; Cummings, Christopher T; Thorburn, Jacqueline; Morgan, Michael J; Thorburn, Andrew

    2012-02-01

    Chloroquine (CQ) is a 4-aminoquinoline drug used for the treatment of diverse diseases. It inhibits lysosomal acidification and therefore prevents autophagy by blocking autophagosome fusion and degradation. In cancer treatment, CQ is often used in combination with chemotherapeutic drugs and radiation because it has been shown to enhance the efficacy of tumor cell killing. Since CQ and its derivatives are the only inhibitors of autophagy that are available for use in the clinic, multiple ongoing clinical trials are currently using CQ or hydroxychloroquine (HCQ) for this purpose, either alone, or in combination with other anticancer drugs. Here we show that in the mouse breast cancer cell lines, 67NR and 4T1, autophagy is induced by the DNA damaging agent cisplatin or by drugs that selectively target autophagy regulation, the PtdIns3K inhibitor LY294002, and the mTOR inhibitor rapamycin. In combination with these drugs, CQ sensitized to these treatments, though this effect was more evident with LY294002 and rapamycin treatment. Surprisingly, however, in these experiments CQ sensitization occurred independent of autophagy inhibition, since sensitization was not mimicked by Atg12, Beclin 1 knockdown or bafilomycin treatment, and occurred even in the absence of Atg12. We therefore propose that although CQ might be helpful in combination with cancer therapeutic drugs, its sensitizing effects can occur independently of autophagy inhibition. Consequently, this possibility should be considered in the ongoing clinical trials where CQ or HCQ are used in the treatment of cancer, and caution is warranted when CQ treatment is used in cytotoxic assays in autophagy research. PMID:22252008

  17. Chloroquine enhanced the anticancer capacity of VNP20009 by inhibiting autophagy

    PubMed Central

    Zhang, Xiaoxin; Xu, Qiaoqiao; Zhang, Zhuangzhuang; Cheng, Wei; Cao, Wenmin; Jiang, Chizhou; Han, Chao; Li, Jiahuang; Hua, Zichun

    2016-01-01

    Bacteria-based living anticancer agents have emerged as promising therapeutics. However, the functional role of autophagy in bacterial cancer therapy has been little investigated. In this study, Salmonella VNP20009 induced autophagy in B16F10 cells, which is an unfavorable factor in bacterial cancer therapy. Inhibiting the induction of autophagy by chloroquine or siRNA in bacterial cancer therapy dose- and time-dependently promoted cell death. The combined therapy of VNP20009 and chloroquine not only enhanced the bacterial tumor targeting ability but also facilitated the infiltration of immune cells into the tumor. Our results showed that the combined therapy of VNP20009 and chloroquine could significantly inhibit tumor growth and prolong mouse survival time. This study provides a novel strategy for improving the anti-cancer efficacy of bacterial cancer therapy. PMID:27412722

  18. Selective elution of HLA antigens and beta 2-microglobulin from human platelets by chloroquine diphosphate

    SciTech Connect

    Kao, K.J.

    1988-01-01

    To determine whether chloroquine can specifically elute HLA antigens and beta 2-microglobulin (beta 2-M) from the platelet surface, quantitative immunofluorescence flow cytometry and monoclonal antibodies were used to show that HLA antigens and beta 2-M were proportionally eluted from the platelet surface without affecting the membrane glycoproteins IIb and IIIa. Second, an autoradiogram of electrophoresed I-125-labeled platelets showed that only beta 2-M but not other I-125-labeled membrane proteins could be eluted. Although HLA antigens were poorly labeled by I-125 and could not be detected on the autoradiogram, the eluted HLA antigens could be detected by anti-HLA monoclonal antibody and immunoblotting techniques. No loss of plasma membrane integrity was observed by transmission electron microscopy after chloroquine treatment of platelets. The results indicate that chloroquine selectively elutes HLA antigens and their noncovalently associated beta 2-M without affecting other integral platelet membrane proteins.

  19. Interaction between chloroquine sulphate and aqueous extract of Azadirachta indica A. Juss (Meliaceae) in rabbits.

    PubMed

    Nwafor, Sunday Vitalis; Akah, Peter Achunike; Okoli, Charles Obgonnaya; Onyirioha, Adaoma Chinaemerem; Nworu, Chukwuemeka Sylvesta

    2003-12-01

    This study was carried out to investigate the effect of concurrent oral administration of aqueous leaf extract of Azadirachta indica (Meliaceae) on the pharmacokinetic properties of chloroquine sulphate in experimental rabbits. The results indicated that concurrent administration of both agents resulted in a significant decrease in serum concentration, slower absorption and elimination as well as longer half-life of chloroquine sulphate. The highest relative decrease of 78.0% was recorded 4 hours after concurrent administration, while the smallest decrease (64.6%) occurred 24 hours after concurrent administration. Significant reductions were also noted in some pharmacokinetic parameters of chloroquine and included the area under the curve (71.9%), maximum serum concentration (69.8%), absorption rate constant (37.3%), elimination rate constant (53.9%), clearance rate (76.5%) and volume of distribution (47.2%). However, there was a pronounced increase in the half-life of the drug (125.7%). PMID:14769237

  20. Metabolic and structural consequences of ethanol and chloroquin administration during gestation on the developing fetus

    SciTech Connect

    Sharma, A.; Rawat, A.K.

    1987-05-01

    In the present study the effects of ethanol and chloroquin administration during gestation have been investigated on the developing rat fetus. Ethanol was given in liquid Sustacal diet as 30% of calories and controls were fed isocaloric sucrose-diet. Chloroquin was given intragastrically corresponding controls received saline. Chloroquin resulted in prenatal growth retardation leading to maximum decrease of 46% in body weight of the fetus. It also resulted in 30% higher incidence of hepatomegaly; 15% higher incidence of liquification of visceral organs; 34% decrease in the ossification of sternum; 9% higher defects of cleft palate, wrist drop, clubbed foot and brain liquification compared to the corresponding controls. Ethanol resulted in pre and post-natal growth retardation, cleft palate, still births and lowered brain weights. Fetuses from the ethanol-fed group also showed inhibited protein synthesis, RNA and DNA synthesis in the brain compared to the controls.

  1. Repositioning of Tyrosine Kinase Inhibitors as Antagonists of ATP-Binding Cassette Transporters in Anticancer Drug Resistance

    PubMed Central

    Wang, Yi-Jun; Zhang, Yun-Kai; Kathawala, Rishil J.; Chen, Zhe-Sheng

    2014-01-01

    The phenomenon of multidrug resistance (MDR) has attenuated the efficacy of anticancer drugs and the possibility of successful cancer chemotherapy. ATP-binding cassette (ABC) transporters play an essential role in mediating MDR in cancer cells by increasing efflux of drugs from cancer cells, hence reducing the intracellular accumulation of chemotherapeutic drugs. Interestingly, small-molecule tyrosine kinase inhibitors (TKIs), such as AST1306, lapatinib, linsitinib, masitinib, motesanib, nilotinib, telatinib and WHI-P154, have been found to have the capability to overcome anticancer drug resistance by inhibiting ABC transporters in recent years. This review will focus on some of the latest and clinical developments with ABC transporters, TKIs and anticancer drug resistance. PMID:25268163

  2. Adjudin disrupts spermatogenesis by targeting drug transporters: Lesson from the breast cancer resistance protein (BCRP).

    PubMed

    Qian, Xiaojing; Cheng, Yan-Ho; Jenardhanan, Pranitha; Mruk, Dolores D; Mathur, Premendu P; Xia, Weiliang; Silvestrini, Bruno; Cheng, C Yan

    2013-04-01

    For non-hormonal male contraceptives that exert their effects in the testis locally instead of via the hypothalamic-pituitary-testicular axis, such as adjudin that disrupts germ cell adhesion, a major hurdle in their development is to improve their bioavailability so that they can be efficiently delivered to the seminiferous epithelium by transporting across the blood-testis barrier (BTB). If this can be done, it would widen the gap between their efficacy and general toxicity. However, Sertoli cells that constitute the BTB, peritubular myoid cells in the tunica propria, germ cells at different stages of their development, as well as endothelial cells that constitute the microvessels in the interstitium are all equipped with multiple drug transporters, most notably efflux drug transporters, such as P-glycoprotein, multidrug resistance-related protein 1 (MRP1) and breast cancer resistance protein (BCRP) that can actively prevent drugs (e.g., adjudin) from entering the seminiferous epithelium to exert their effects. Recent studies have shown that BCRP is highly expressed by endothelial cells of the microvessels in the interstitium in the testis and also peritubular myoid cells in tunica propria even though it is absent from Sertoli cells at the site of the BTB. Furthermore, BCRP is also expressed spatiotemporally by Sertoli cells and step 19 spermatids in the rat testis and stage-specifically, limiting to stage VII‒VIII of the epithelial cycle, and restricted to the apical ectoplasmic specialization [apical ES, a testis-specific F-actin-rich adherens junction (AJ)]. Interestingly, adjudin was recently shown to be capable of downregulating BCRP expression at the apical ES. In this Opinion article, we critically discuss the latest findings on BCRP; in particular, we provide some findings utilizing molecular modeling to define the interacting domains of BCRP with adjudin. Based on this information, it is hoped that the next generation of adjudin analogs to be

  3. Chloroquine retinopathy: pattern of presentation in Ibadan, Sub-Sahara Africa.

    PubMed

    Oluleye, T S; Babalola, Y; Ijaduola, M

    2016-01-01

    BackgroundSelf-medication with chloroquine is common in Ibadan, Sub-Sahara Africa. Retinopathy from chloroquine is not uncommon. The aim was to determine the pattern of presentation.MethodologyCases of Chloroquine retinopathy seen at the Retina and Vitreous Unit of the University College Hospital, Ibadan between 2008 and 2014 were reviewed. Information on age, sex, duration of chloroquine use, and visual loss were retrieved. Visual acuity at presentation, anterior, and posterior segment findings were documented. The results were analyzed using proportions and percentages.ResultsFourteen cases were seen during the study period. Mean age was 50.7 years. Male to female ratio was 3.5 : 1. Average duration of visual loss before presentation was 2.7 years. Average duration of self-medication with chloroquine was 5.3 years. Presenting visual acuity showed 2(14%) cases of bilateral blindness(VA<3/60 in both eyes); 5(35.7%) cases of uniocular blindness; three cases of bilateral low vision(VA worse than 6/18 but better than 3/60). Anterior segment examination showed abnormal sluggish pupillary reaction in those with severe affectation. Dilated fundoscopy showed features ranging from mild macular pigmentary changes and bulls eye maculopathy to overt extensive retinal degeneration involving the posterior pole, attenuation of retinal vessels, optic atrophy, and beaten bronze appearance of atrophic maculopathy.ConclusionChloroquine retinopathy is not uncommon in Ibadan, Sub-Sahara Africa. Bulls eye maculopathy, extensive retinal, and macular degeneration with optic atrophy are the main presentations. Public health education is imperative. PMID:26427986

  4. Structural, electronic, mechanical, and transport properties of phosphorene nanoribbons: Negative differential resistance behavior

    NASA Astrophysics Data System (ADS)

    Maity, Ajanta; Singh, Akansha; Sen, Prasenjit; Kibey, Aniruddha; Kshirsagar, Anjali; Kanhere, Dilip G.

    2016-08-01

    Structural, electronic, mechanical, and transport properties of two different types of phosphorene nanoribbons are calculated within the density functional theory and nonequilibrium Green's function formalisms. Armchair nanoribbons turn out to be semiconductors at all widths considered. Zigzag nanoribbons are metallic in their layer-terminated structure, but undergo Peierls-like transition at the edges. Armchair nanoribbons have smaller Young's modulus compared to a monolayer, while zigzag nanoribbons have larger Young's modulus. Edge reconstruction further increases the Young's modulus of zigzag nanoribbons. A two-terminal device made of zigzag nanoribbons show negative differential resistance behavior that is robust with respect to edge reconstruction. We have also calculated the I -V characteristics for two nonzero gate voltages. The results show that the zigzag nanoribbons display strong p -type character.

  5. The varied functions of aluminium-activated malate transporters-much more than aluminium resistance.

    PubMed

    Palmer, Antony J; Baker, Alison; Muench, Stephen P

    2016-06-15

    The ALMT (aluminium-activated malate transporter) family comprises a functionally diverse but structurally similar group of ion channels. They are found ubiquitously in plant species, expressed throughout different tissues, and located in either the plasma membrane or tonoplast. The first family member identified was TaALMT1, discovered in wheat root tips, which was found to be involved in aluminium resistance by means of malate exudation into the soil. However, since this discovery other family members have been shown to have many other functions such as roles in stomatal opening, general anionic homoeostasis, and in economically valuable traits such as fruit flavour. Recent evidence has also shown that ALMT proteins can act as key molecular actors in GABA (γ-aminobutyric acid) signalling, the first evidence that GABA can act as a signal transducer in plants. PMID:27284052

  6. Acute Pretreatment with Chloroquine Attenuates Renal I/R Injury in Rats

    PubMed Central

    Todorovic, Zoran; Medic, Branislava; Basta-Jovanovic, Gordana; Radojevic Skodric, Sanja; Stojanovic, Radan; Rovcanin, Branislav; Prostran, Milica

    2014-01-01

    Background Acute kidney injury (AKI) still remains an unresolved problem in pharmacotherapy and renal inflammation is a major factor in its development. Chloroquine, a well-known antimalarial drug, posses pleitropic effects as well: antiinflammatory, anticoagulant and vascular actions. The effects of chloroquine on renal function may involve significant increase in urine flow rate, glomerular filtration rate and sodium excretion, as well as stimulation of nitric oxide synthase. However, its role in experimental models of renal I/R injury is unknown. We aimed to analyze the acute effects of a single-dose intravenous chloroquine administered at three different times in the experimental model of I/R injury in rat. Methods Rats were subjected to bilateral renal ischemia (45 min) followed by reperfusion with saline lasting 4 hours. Chloroquine was administered in doses of 0.3 mg/kg i.v. and 3 mg/kg i.v. 30 min before ischemia, 30 min before reperfusion and 5 min before reperfusion. Selected a hemodynamic, biochemical and morphological parameters were followed in the Sham-operated animals and rats subjected to I/R injury and pretreated with saline or chloroquine. Results Chloroquine (0.3 and 3 mg/kg, i.v.) protected the I/R injured kidney in an U-shaped manner. Both doses were protective regarding biochemical and histological markers of the I/R injury (serum urea, creatinine and fractional excretion of sodium, as well as total histological score, tubular necrosis score and KIM-1 staining score) (P<0.05 vs. corresponding controls, i.e. rats subjected to I/R injury and treated with saline only). The protective effects of the lower dose of chloroquine were more profound. Time-related differences between pretreatments were not observed (P>0.05, all). Conclusion Our study shows for the first time that a single dose of chloroquine (0.3 mg/kg i.v.) could afford significant protection of the injured rat kidney. PMID:24681567

  7. Effect of Prostaglandin E2 on Multidrug Resistance Transporters In Human Placental Cells

    PubMed Central

    Lee, Gene T.; Dong, Yafeng; Zhou, Helen; He, Lily; Weiner, Carl P.

    2014-01-01

    Prostaglandin (PG) E2, a major product of cyclooxygenase (COX)-2, acts as an immunomodulator at the maternal-fetal interface during pregnancy. It exerts biologic function through interaction with E-prostanoid (EP) receptors localized to the placenta. The activation of the COX-2/PGE2/EP signal pathway can alter the expression of the ATP-binding cassette (ABC) transporters, multidrug resistance protein 1 [P-glycoprotein (Pgp); gene: ABCB1], and breast cancer resistance protein (BCRP; gene: ABCG2), which function to extrude drugs and xenobiotics from cells. In the placenta, PGE2-mediated changes in ABC transporter expression could impact fetal drug exposure. Furthermore, understanding the signaling cascades involved could lead to strategies for the control of Pgp and BCRP expression levels. We sought to determine the impact of PGE2 signaling mechanisms on Pgp and BCRP in human placental cells. The treatment of placental cells with PGE2 up-regulated BCRP expression and resulted in decreased cellular accumulation of the fluorescent substrate Hoechst 33342. Inhibiting the EP1 and EP3 receptors with specific antagonists attenuated the increase in BCRP. EP receptor signaling results in activation of transcription factors, which can affect BCRP expression. Although PGE2 decreased nuclear factor κ-light chain-enhancer of activated B activation and increased activator protein 1, chemical inhibition of these inflammatory transcription factors did not blunt BCRP up-regulation by PGE2. Though PGE2 decreased Pgp mRNA, Pgp expression and function were not significantly altered. Overall, these findings suggest a possible role for PGE2 in the up-regulation of placental BCRP expression via EP1 and EP3 receptor signaling cascades. PMID:25261564

  8. Effect of prostaglandin E2 on multidrug resistance transporters in human placental cells.

    PubMed

    Mason, Clifford W; Lee, Gene T; Dong, Yafeng; Zhou, Helen; He, Lily; Weiner, Carl P

    2014-12-01

    Prostaglandin (PG) E2, a major product of cyclooxygenase (COX)-2, acts as an immunomodulator at the maternal-fetal interface during pregnancy. It exerts biologic function through interaction with E-prostanoid (EP) receptors localized to the placenta. The activation of the COX-2/PGE2/EP signal pathway can alter the expression of the ATP-binding cassette (ABC) transporters, multidrug resistance protein 1 [P-glycoprotein (Pgp); gene: ABCB1], and breast cancer resistance protein (BCRP; gene: ABCG2), which function to extrude drugs and xenobiotics from cells. In the placenta, PGE2-mediated changes in ABC transporter expression could impact fetal drug exposure. Furthermore, understanding the signaling cascades involved could lead to strategies for the control of Pgp and BCRP expression levels. We sought to determine the impact of PGE2 signaling mechanisms on Pgp and BCRP in human placental cells. The treatment of placental cells with PGE2 up-regulated BCRP expression and resulted in decreased cellular accumulation of the fluorescent substrate Hoechst 33342. Inhibiting the EP1 and EP3 receptors with specific antagonists attenuated the increase in BCRP. EP receptor signaling results in activation of transcription factors, which can affect BCRP expression. Although PGE2 decreased nuclear factor κ-light chain-enhancer of activated B activation and increased activator protein 1, chemical inhibition of these inflammatory transcription factors did not blunt BCRP up-regulation by PGE2. Though PGE2 decreased Pgp mRNA, Pgp expression and function were not significantly altered. Overall, these findings suggest a possible role for PGE2 in the up-regulation of placental BCRP expression via EP1 and EP3 receptor signaling cascades. PMID:25261564

  9. Resistance to Diet-Induced Obesity and Associated Metabolic Perturbations in Haploinsufficient Monocarboxylate Transporter 1 Mice

    PubMed Central

    Steiner, Nadia; Carneiro, Lionel; Favrod, Céline; Preitner, Frédéric; Thorens, Bernard; Stehle, Jean-Christophe; Dix, Laure; Pralong, François; Magistretti, Pierre J.; Pellerin, Luc

    2013-01-01

    The monocarboxylate transporter 1 (MCT1 or SLC16A1) is a carrier of short-chain fatty acids, ketone bodies, and lactate in several tissues. Genetically modified C57BL/6J mice were produced by targeted disruption of the mct1 gene in order to understand the role of this transporter in energy homeostasis. Null mutation was embryonically lethal, but MCT1+/− mice developed normally. However, when fed high fat diet (HFD), MCT1+/− mice displayed resistance to development of diet-induced obesity (24.8% lower body weight after 16 weeks of HFD), as well as less insulin resistance and no hepatic steatosis as compared to littermate MCT1+/+ mice used as controls. Body composition analysis revealed that reduced weight gain in MCT1+/− mice was due to decreased fat accumulation (50.0% less after 9 months of HFD) notably in liver and white adipose tissue. This phenotype was associated with reduced food intake under HFD (12.3% less over 10 weeks) and decreased intestinal energy absorption (9.6% higher stool energy content). Indirect calorimetry measurements showed ∼ 15% increase in O2 consumption and CO2 production during the resting phase, without any changes in physical activity. Determination of plasma concentrations for various metabolites and hormones did not reveal significant changes in lactate and ketone bodies levels between the two genotypes, but both insulin and leptin levels, which were elevated in MCT1+/+ mice when fed HFD, were reduced in MCT1+/− mice under HFD. Interestingly, the enhancement in expression of several genes involved in lipid metabolism in the liver of MCT1+/+ mice under high fat diet was prevented in the liver of MCT1+/− mice under the same diet, thus likely contributing to the observed phenotype. These findings uncover the critical role of MCT1 in the regulation of energy balance when animals are exposed to an obesogenic diet. PMID:24367518

  10. Ex Vivo Drug Susceptibility Testing and Molecular Profiling of Clinical Plasmodium falciparum Isolates from Cambodia from 2008 to 2013 Suggest Emerging Piperaquine Resistance.

    PubMed

    Chaorattanakawee, Suwanna; Saunders, David L; Sea, Darapiseth; Chanarat, Nitima; Yingyuen, Kritsanai; Sundrakes, Siratchana; Saingam, Piyaporn; Buathong, Nillawan; Sriwichai, Sabaithip; Chann, Soklyda; Se, Youry; Yom, You; Heng, Thay Kheng; Kong, Nareth; Kuntawunginn, Worachet; Tangthongchaiwiriya, Kuntida; Jacob, Christopher; Takala-Harrison, Shannon; Plowe, Christopher; Lin, Jessica T; Chuor, Char Meng; Prom, Satharath; Tyner, Stuart D; Gosi, Panita; Teja-Isavadharm, Paktiya; Lon, Chanthap; Lanteri, Charlotte A

    2015-08-01

    Cambodia's first-line artemisinin combination therapy, dihydroartemisinin-piperaquine (DHA-PPQ), is no longer sufficiently curative against multidrug-resistant Plasmodium falciparum malaria at some Thai-Cambodian border regions. We report recent (2008 to 2013) drug resistance trends in 753 isolates from northern, western, and southern Cambodia by surveying for ex vivo drug susceptibility and molecular drug resistance markers to guide the selection of an effective alternative to DHA-PPQ. Over the last 3 study years, PPQ susceptibility declined dramatically (geomean 50% inhibitory concentration [IC50] increased from 12.8 to 29.6 nM), while mefloquine (MQ) sensitivity doubled (67.1 to 26 nM) in northern Cambodia. These changes in drug susceptibility were significantly associated with a decreased prevalence of P. falciparum multidrug resistance 1 gene (Pfmdr1) multiple copy isolates and coincided with the timing of replacing artesunate-mefloquine (AS-MQ) with DHA-PPQ as the first-line therapy. Widespread chloroquine resistance was suggested by all isolates being of the P. falciparum chloroquine resistance transporter gene CVIET haplotype. Nearly all isolates collected from the most recent years had P. falciparum kelch13 mutations, indicative of artemisinin resistance. Ex vivo bioassay measurements of antimalarial activity in plasma indicated 20% of patients recently took antimalarials, and their plasma had activity (median of 49.8 nM DHA equivalents) suggestive of substantial in vivo drug pressure. Overall, our findings suggest DHA-PPQ failures are associated with emerging PPQ resistance in a background of artemisinin resistance. The observed connection between drug policy changes and significant reduction in PPQ susceptibility with mitigation of MQ resistance supports reintroduction of AS-MQ, in conjunction with monitoring of the P. falciparum mdr1 copy number, as a stop-gap measure in areas of DHA-PPQ failure. PMID:26014942

  11. Ex Vivo Drug Susceptibility Testing and Molecular Profiling of Clinical Plasmodium falciparum Isolates from Cambodia from 2008 to 2013 Suggest Emerging Piperaquine Resistance

    PubMed Central

    Chaorattanakawee, Suwanna; Saunders, David L.; Sea, Darapiseth; Chanarat, Nitima; Yingyuen, Kritsanai; Sundrakes, Siratchana; Saingam, Piyaporn; Buathong, Nillawan; Sriwichai, Sabaithip; Chann, Soklyda; Se, Youry; Yom, You; Heng, Thay Kheng; Kong, Nareth; Kuntawunginn, Worachet; Tangthongchaiwiriya, Kuntida; Jacob, Christopher; Takala-Harrison, Shannon; Plowe, Christopher; Lin, Jessica T.; Chuor, Char Meng; Prom, Satharath; Tyner, Stuart D.; Gosi, Panita; Teja-Isavadharm, Paktiya; Lon, Chanthap

    2015-01-01

    Cambodia's first-line artemisinin combination therapy, dihydroartemisinin-piperaquine (DHA-PPQ), is no longer sufficiently curative against multidrug-resistant Plasmodium falciparum malaria at some Thai-Cambodian border regions. We report recent (2008 to 2013) drug resistance trends in 753 isolates from northern, western, and southern Cambodia by surveying for ex vivo drug susceptibility and molecular drug resistance markers to guide the selection of an effective alternative to DHA-PPQ. Over the last 3 study years, PPQ susceptibility declined dramatically (geomean 50% inhibitory concentration [IC50] increased from 12.8 to 29.6 nM), while mefloquine (MQ) sensitivity doubled (67.1 to 26 nM) in northern Cambodia. These changes in drug susceptibility were significantly associated with a decreased prevalence of P. falciparum multidrug resistance 1 gene (Pfmdr1) multiple copy isolates and coincided with the timing of replacing artesunate-mefloquine (AS-MQ) with DHA-PPQ as the first-line therapy. Widespread chloroquine resistance was suggested by all isolates being of the P. falciparum chloroquine resistance transporter gene CVIET haplotype. Nearly all isolates collected from the most recent years had P. falciparum kelch13 mutations, indicative of artemisinin resistance. Ex vivo bioassay measurements of antimalarial activity in plasma indicated 20% of patients recently took antimalarials, and their plasma had activity (median of 49.8 nM DHA equivalents) suggestive of substantial in vivo drug pressure. Overall, our findings suggest DHA-PPQ failures are associated with emerging PPQ resistance in a background of artemisinin resistance. The observed connection between drug policy changes and significant reduction in PPQ susceptibility with mitigation of MQ resistance supports reintroduction of AS-MQ, in conjunction with monitoring of the P. falciparum mdr1 copy number, as a stop-gap measure in areas of DHA-PPQ failure. PMID:26014942

  12. Chloroquine enhances the chemotherapeutic activity of 5-fluorouracil in a colon cancer cell line via cell cycle alteration.

    PubMed

    Choi, Jung-Hye; Yoon, Jin Sun; Won, Young-Woong; Park, Byeong-Bae; Lee, Young Yiul

    2012-07-01

    Autophagy is a conserved catabolic process that degrades cytoplasmic proteins and organelles for recycling. The role of autophagy in tumorigenesis is controversial because autophagy can be either protective or damaging to tumor cells, and its effects may change during tumor progression. A number of cancer cell lines have been exposed to chloroquine, an anti-malarial drug, with the aim of inhibiting cell growth and inducing cell death. In addition, chloroquine inhibits a late phase of autophagy. This study was conducted to investigate the anti-cancer effect of autophagy inhibition, using chloroquine together with 5-fluorouracil (5-FU) in a colon cancer cell line. Human colon cancer DLD-1 cells were treated with 5-FU (10 μΜ) or chloroquine (100 μΜ), or a combination of both. Autophagy was evaluated by western blot analysis of microtubule-associated protein light chain3 (LC3). Proliferative activity, alterations of the cell cycle, and apoptosis were measured by MTT assays, flow cytometry, and western blotting. LC3-II protein increased after treatment with 5-FU, and chloroquine potentiated the cytotoxicity of 5-FU. MTT assays showed that 5-FU inhibited proliferation of the DLD-1 cells and that chloroquine enhanced this inhibitory effect of 5-FU. The combination of 5-FU and chloroquine induced G1 arrest, up-regulation of p27 and p53, and down-regulation of CDK2 and cyclin D1. These results suggest that chloroquine may potentiate the anti-cancer effect of 5-FU via cell cycle inhibition. Chloroquine potentiates the anti-cancer effect of 5-FU in colon cancer cells. Supplementation of conventional chemotherapy with chloroquine may provide a new cancer therapy modality. PMID:22716215

  13. Mutation of G234 amino acid residue in candida albicans drug-resistance-related protein Rta2p is associated with fluconazole resistance and dihydrosphingosine transport.

    PubMed

    Zhang, Shi-Qun; Miao, Qi; Li, Li-Ping; Zhang, Lu-Lu; Yan, Lan; Jia, Yu; Cao, Yong-Bing; Jiang, Yuan-Ying

    2015-01-01

    Widespread and repeated use of azoles has led to the rapid development of drug resistance in Candida albicans. Our previous study found Rta2p, a membrane protein with 7 transmembrane domains, was involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in C. albicans. Conserved amino acids in the transmembrane domain of Rta2p were subjected to site-directed mutagenesis. The sensitivity of C. albicans to fluconazole in vitro was examined by minimum inhibitory concentration and killing assay, and the therapeutic efficacy of fluconazole in vivo was performed by systemic mice candidiasis model. Furthermore, dihydrosphingosine transport activity was detected by NBD labeled D-erythro-dihydrosphingosine uptake and release assay, and the sensitivity to sphingolipid biosynthesis inhibitors. We successfully constructed 14 mutant strains of Rta2p, screened them by minimum inhibitory concentration and found Ca(2+) did not completely induce fluconazole resistance with G158E and G234S mutations. Furthermore, we confirmed that G234S mutant enhanced the therapeutic efficacy of fluconazole against systemic candidiasis and significantly increased the accumulation of dihydrosphingosine by decreasing its release. However, G158E mutant didn't affect drug therapeutic efficacy in vivo and dihydrosphingosine transport in C. albicans. G234 of Rta2p in C. albicans is crucial in calcineurin-mediated fluconazole resistance and dihydrosphingosine transport. PMID:26220356

  14. Mutation of G234 amino acid residue in Candida albicans drug-resistance-related protein Rta2p is associated with fluconazole resistance and dihydrosphingosine transport

    PubMed Central

    Zhang, Shi-Qun; Miao, Qi; Li, Li-Ping; Zhang, Lu-lu; Yan, Lan; Jia, Yu; Cao, Yong-Bing; Jiang, Yuan-Ying

    2015-01-01

    Widespread and repeated use of azoles has led to the rapid development of drug resistance in Candida albicans. Our previous study found Rta2p, a membrane protein with 7 transmembrane domains, was involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in C. albicans. Conserved amino acids in the transmembrane domain of Rta2p were subjected to site-directed mutagenesis. The sensitivity of C. albicans to fluconazole in vitro was examined by minimum inhibitory concentration and killing assay, and the therapeutic efficacy of fluconazole in vivo was performed by systemic mice candidiasis model. Furthermore, dihydrosphingosine transport activity was detected by NBD labeled D-erythro-dihydrosphingosine uptake and release assay, and the sensitivity to sphingolipid biosynthesis inhibitors. We successfully constructed 14 mutant strains of Rta2p, screened them by minimum inhibitory concentration and found Ca2+ did not completely induce fluconazole resistance with G158E and G234S mutations. Furthermore, we confirmed that G234S mutant enhanced the therapeutic efficacy of fluconazole against systemic candidiasis and significantly increased the accumulation of dihydrosphingosine by decreasing its release. However, G158E mutant didn't affect drug therapeutic efficacy in vivo and dihydrosphingosine transport in C. albicans. G234 of Rta2p in C. albicans is crucial in calcineurin-mediated fluconazole resistance and dihydrosphingosine transport. PMID:26220356

  15. Report on audit of the Department of Energy`s Transportation Accident Resistant Container Program

    SciTech Connect

    1995-10-11

    The U.S. Department of Energy (Department) has ultimate responsibility for the safety of all nuclear explosives and weapons operations conducted by the Department and its contractors. The Department also has joint responsibility for the safety of nuclear weapons in the custody of the Armed Services. Since the 1970s, the Department has designed, developed, and produced accident resistant containers to promote safety when transporting certain types of nuclear weapons by air. After successfully developing and modifying accident resistant containers for use on Army helicopters, the Department subsequently designed, modified, and produced similar containers for the United States Air Force. Because the Department spent millions of dollars on this project, we conducted the audit to determine if the Department had adequate controls in place to preclude the development and production of projects which did not have customer agreement or meet customer requirements. One goal of the Department`s Strategic Plan is to ensure that customer expectations are met by having them participate in the planning process. Although nuclear safety responsibility was shared with the Department of Defense, the Department designed and produced 87 accident resistant containers for about $29 million when the customer did not want them and expressed no desire to use these containers. This occurred because the Department unilaterally decided to produce containers without ensuring that the containers met customer expectations. There may be circumstances where the Department will do some preliminary design and testing before agreeing with the Department of Defense on requirements. However, the Departments of Energy and Defense should reach agreement on the requirement for products before final design and production, otherwise funds will be spent unnecessarily.

  16. MULTIDRUG RESISTANT TRANSPORT ACTIVITY PROTECTS OOCYTES FROM CHEMOTHERAPEUTIC AGENTS AND CHANGES DURING OOCYTE MATURATION

    PubMed Central

    Brayboy, Lynae M.; Oulhen, Nathalie; Witmyer, Jeannine; Robins, Jared; Carson, Sandra; Wessel, Gary M.

    2013-01-01

    Objective To determine the multidrug resistant (MDR) transporter activity in oocytes and their potential role in oocyte susceptibility to chemotherapy. Design Experimental laboratory study Setting University and Academic Center for reproductive medicine. Patients/Animals Women with eggs retrieved for ICSI cycles and adult female FVBN and B6C3F1 mouse strains. Intervention Inhibition of MDR activity in oocytes. Main Outcome measure(s) Efflux activity of MDRs using quantitative fluorescent dye efflux and oocyte cell death when exposed to chemotherapy. Results Oocytes effluxed fluorescent reporters and this activity was significantly reduced in the presence of the MDR inhibitor PSC 833. GV oocytes are more efficient at efflux compared to M2 oocytes. Human oocytes exposed to cyclophosphamide and PSC 833 showed cell death using two different viability assays compared to controls and those exposed to cyclophosphamide alone. Immunoblots detected MDR-1 in all oocytes with the greatest accumulation in the GV stage. Conclusions Oocytes have a vast repertoire of active MDRs. The implications of this study are that these protective mechanisms are important during oogenesis, and these activities change with maturation, increasing susceptibility to toxicants. Future directions may exploit the up regulation of these transporters during gonadotoxic therapy. PMID:23953328

  17. The secure, transportable, autonomous reactor (STAR): a small proliferation-resistant reactor system for developing countries

    SciTech Connect

    Brown, N W; Hassberger, J A; Smith, C F

    1999-05-27

    The Secure, Transportable, Autonomous Reactor (STAR), is an integrated concept for a small, proliferation-resistant nuclear power system capable of meeting the growing power demands of many regions of the developing world. The STAR approach builds on earlier work investigating the features required for implementation of such a system. The STAR approach includes establishing overall system requirements, conducting research into issues common to four reactor concepts (gas, liquid metal, light water and molten salt), and defining and performing the down-selection to a preferred concept that will serve as the basis for continued development leading to an eventual prototype. The paper indicates that a number of unique and distinguishing innovations are needed to both meet the energy demands of most of the world's developing regions and address growing nuclear proliferation concerns. These technical innovations form much of the basis underlying the STAR concept and include: eliminating on-site refueling and fuel access; incorporating a systems approach to nuclear energy supply and infrastructure design, with all aspects of equipment life, fuel and waste cycles included; small unit size enabling transportability; replaceable standardized modular design; resilient and robust design concepts leading to large safety margins, high reliability and reduced maintenance; simplicity in operation with reliance on autonomous control and remote monitoring; and waste minimization and waste form optimization.

  18. Combinatorial Genetic Modeling of pfcrt-Mediated Drug Resistance Evolution in Plasmodium falciparum.

    PubMed

    Gabryszewski, Stanislaw J; Modchang, Charin; Musset, Lise; Chookajorn, Thanat; Fidock, David A

    2016-06-01

    The emergence of drug resistance continuously threatens global control of infectious diseases, including malaria caused by the protozoan parasite Plasmodium falciparum A critical parasite determinant is the P. falciparum chloroquine resistance transporter (PfCRT), the primary mediator of chloroquine (CQ) resistance (CQR), and a pleiotropic modulator of susceptibility to several first-line artemisinin-based combination therapy partner drugs. Aside from the validated CQR molecular marker K76T, P. falciparum parasites have acquired at least three additional pfcrt mutations, whose contributions to resistance and fitness have been heretofore unclear. Focusing on the quadruple-mutant Ecuadorian PfCRT haplotype Ecu1110 (K76T/A220S/N326D/I356L), we genetically modified the pfcrt locus of isogenic, asexual blood stage P. falciparum parasites using zinc-finger nucleases, producing all possible combinations of intermediate pfcrt alleles. Our analysis included the related quintuple-mutant PfCRT haplotype 7G8 (Ecu1110 + C72S) that is widespread throughout South America and the Western Pacific. Drug susceptibilities and in vitro growth profiles of our combinatorial pfcrt-modified parasites were used to simulate the mutational trajectories accessible to parasites as they evolved CQR. Our results uncover unique contributions to parasite drug resistance and growth for mutations beyond K76T and predict critical roles for the CQ metabolite monodesethyl-CQ and the related quinoline-type drug amodiaquine in driving mutant pfcrt evolution. Modeling outputs further highlight the influence of parasite proliferation rates alongside gains in drug resistance in dictating successful trajectories. Our findings suggest that P. falciparum parasites have navigated constrained pfcrt adaptive landscapes by means of probabilistically rare mutational bursts that led to the infrequent emergence of pfcrt alleles in the field. PMID:26908582

  19. Combinatorial Genetic Modeling of pfcrt-Mediated Drug Resistance Evolution in Plasmodium falciparum

    PubMed Central

    Gabryszewski, Stanislaw J.; Modchang, Charin; Musset, Lise; Chookajorn, Thanat; Fidock, David A.

    2016-01-01

    The emergence of drug resistance continuously threatens global control of infectious diseases, including malaria caused by the protozoan parasite Plasmodium falciparum. A critical parasite determinant is the P. falciparum chloroquine resistance transporter (PfCRT), the primary mediator of chloroquine (CQ) resistance (CQR), and a pleiotropic modulator of susceptibility to several first-line artemisinin-based combination therapy partner drugs. Aside from the validated CQR molecular marker K76T, P. falciparum parasites have acquired at least three additional pfcrt mutations, whose contributions to resistance and fitness have been heretofore unclear. Focusing on the quadruple-mutant Ecuadorian PfCRT haplotype Ecu1110 (K76T/A220S/N326D/I356L), we genetically modified the pfcrt locus of isogenic, asexual blood stage P. falciparum parasites using zinc-finger nucleases, producing all possible combinations of intermediate pfcrt alleles. Our analysis included the related quintuple-mutant PfCRT haplotype 7G8 (Ecu1110 + C72S) that is widespread throughout South America and the Western Pacific. Drug susceptibilities and in vitro growth profiles of our combinatorial pfcrt-modified parasites were used to simulate the mutational trajectories accessible to parasites as they evolved CQR. Our results uncover unique contributions to parasite drug resistance and growth for mutations beyond K76T and predict critical roles for the CQ metabolite monodesethyl-CQ and the related quinoline-type drug amodiaquine in driving mutant pfcrt evolution. Modeling outputs further highlight the influence of parasite proliferation rates alongside gains in drug resistance in dictating successful trajectories. Our findings suggest that P. falciparum parasites have navigated constrained pfcrt adaptive landscapes by means of probabilistically rare mutational bursts that led to the infrequent emergence of pfcrt alleles in the field. PMID:26908582

  20. Role of multi-drug resistance-associated protein-1 transporter in statin-induced myopathy.

    PubMed

    Dorajoo, Rajkumar s o; Pereira, Barry P; Yu, Zou; Gopalakrishnakone, P; Leong, Cheng Chee; Wee, Aileen; Lee, Edmund

    2008-04-01

    This study investigated the effects of probenecid to inhibit the multi-drug resistance-associated protein-1 (MRP-1) in mediating the efflux and myotoxicity in rat skeletal muscles, with administration of rosuvastatin. Male Sprague-Dawley rats were administered daily, for 15 days, with either rosuvastatin (50, 100 or 200 mg/kg) or probenecid (100 mg/kg) alone, or with a combination of rosuvastatin (50, 100 or 200 mg/kg) and probenecid (100 mg/kg). Skeletal muscle toxicity was elevated with probenecid administered with 200 mg/kg/day of rosuvastatin, with the elevation of creatine kinase by 12-fold, alanine aminotrasferase by 10-fold and creatinine by 9-fold at day 15, with no adverse effects observed when probenecid was given alone. Mitochondria ultrastructural damage with enlargement, disruption, cristolysis and vaculation was seen in the soleus and plantaris of animals administered with probenecid and high dosages of statin. These muscles were also expressing more succinic dehydrogenase (SDH)-positive and cytochrome oxidase (CyOX)-positive fibers. Although generally well-tolerated, statins produce a variety of adverse skeletal muscle events. Hydrophilic statins, with reduced levels of non-specific passive diffusion rates into extra-hepatic tissues, are still seen to produce myopathy. This highlights the important roles of transport mechanisms in statin transport at the skeletal muscles. Excessive influx, reduced efflux or the combination of the two could result in elevated cellular levels of statins at the skeletal muscles, resulting in toxicity. This study provides preliminary evidence that the MRP-1 transporter and efflux at skeletal muscles possibly play significant roles in statin-induced myopathy. PMID:18509883

  1. A Silent ABC Transporter Isolated from Streptomyces rochei F20 Induces Multidrug Resistance

    PubMed Central

    Fernández-Moreno, Miguel A.; Carbó, Lázaro; Cuesta, Trinidad; Vallín, Carlos; Malpartida, Francisco

    1998-01-01

    In the search for heterologous activators for actinorhodin production in Streptomyces lividans, 3.4 kb of DNA from Streptomyces rochei F20 (a streptothricin producer) were characterized. Subcloning experiments showed that the minimal DNA fragment required for activation was 0.4 kb in size. The activation is mediated by increasing the levels of transcription of the actII-ORF4 gene. Sequencing of the minimal activating fragment did not reveal any clues about its mechanism; nevertheless, it was shown to overlap the 3′ end of two convergent genes, one of whose translated products (ORF2) strongly resembles that of other genes belonging to the ABC transporter superfamily. Computer-assisted analysis of the 3.4-kb DNA sequence showed the 3′ terminus of an open reading frame (ORF), i.e., ORFA, and three complete ORFs (ORF1, ORF2, and ORFB). Searches in the databases with their respective gene products revealed similarities for ORF1 and ORF2 with ATP-binding proteins and transmembrane proteins, respectively, which are found in members of the ABC transporter superfamily. No similarities for ORFA and ORFB were found in the databases. Insertional inactivation of ORF1 and ORF2, their transcription analysis, and their cloning in heterologous hosts suggested that these genes were not expressed under our experimental conditions; however, cloning of ORF1 and ORF2 together (but not separately) under the control of an expressing promoter induced resistance to several chemically different drugs: oleandomycin, erythromycin, spiramycin, doxorubicin, and tetracycline. Thus, this genetic system, named msr, is a new bacterial multidrug ABC transporter. PMID:9696745

  2. Sulfadiazine resistance in Toxoplasma gondii: no involvement of overexpression or polymorphisms in genes of therapeutic targets and ABC transporters

    PubMed Central

    Doliwa, Christelle; Escotte-Binet, Sandie; Aubert, Dominique; Sauvage, Virginie; Velard, Frédéric; Schmid, Aline; Villena, Isabelle

    2013-01-01

    Several treatment failures have been reported for the treatment of toxoplasmic encephalitis, chorioretinitis, and congenital toxoplasmosis. Recently we found three Toxoplasma gondii strains naturally resistant to sulfadiazine and we developed in vitro two sulfadiazine resistant strains, RH-RSDZ and ME-49-RSDZ, by gradual pressure. In Plasmodium, common mechanisms of drug resistance involve, among others, mutations and/or amplification within genes encoding the therapeutic targets dhps and dhfr and/or the ABC transporter genes family. To identify genotypic and/or phenotypic markers of resistance in T. gondii, we sequenced and analyzed the expression levels of therapeutic targets dhps and dhfr, three ABC genes, two Pgp, TgABC.B1 and TgABC.B2, and one MRP, TgABC.C1, on sensitive strains compared to sulfadiazine resistant strains. Neither polymorphism nor overexpression was identified. Contrary to Plasmodium, in which mutations and/or overexpression within gene targets and ABC transporters are involved in antimalarial resistance, T. gondii sulfadiazine resistance is not related to these toxoplasmic genes studied. PMID:23707894

  3. Genetic architecture of artemisinin-resistant Plasmodium falciparum.

    PubMed

    Miotto, Olivo; Amato, Roberto; Ashley, Elizabeth A; MacInnis, Bronwyn; Almagro-Garcia, Jacob; Amaratunga, Chanaki; Lim, Pharath; Mead, Daniel; Oyola, Samuel O; Dhorda, Mehul; Imwong, Mallika; Woodrow, Charles; Manske, Magnus; Stalker, Jim; Drury, Eleanor; Campino, Susana; Amenga-Etego, Lucas; Thanh, Thuy-Nhien Nguyen; Tran, Hien Tinh; Ringwald, Pascal; Bethell, Delia; Nosten, Francois; Phyo, Aung Pyae; Pukrittayakamee, Sasithon; Chotivanich, Kesinee; Chuor, Char Meng; Nguon, Chea; Suon, Seila; Sreng, Sokunthea; Newton, Paul N; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Htut, Ye; Han, Kay Thwe; Kyaw, Myat Phone; Faiz, Md Abul; Fanello, Caterina I; Onyamboko, Marie; Mokuolu, Olugbenga A; Jacob, Christopher G; Takala-Harrison, Shannon; Plowe, Christopher V; Day, Nicholas P; Dondorp, Arjen M; Spencer, Chris C A; McVean, Gilean; Fairhurst, Rick M; White, Nicholas J; Kwiatkowski, Dominic P

    2015-03-01

    We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population. PMID:25599401

  4. Genetic architecture of artemisinin-resistant Plasmodium falciparum

    PubMed Central

    Miotto, Olivo; Amato, Roberto; Ashley, Elizabeth A; MacInnis, Bronwyn; Almagro-Garcia, Jacob; Amaratunga, Chanaki; Lim, Pharath; Mead, Daniel; Oyola, Samuel O; Dhorda, Mehul; Imwong, Mallika; Woodrow, Charles; Manske, Magnus; Stalker, Jim; Drury, Eleanor; Campino, Susana; Amenga-Etego, Lucas; Thanh, Thuy-Nhien Nguyen; Tran, Hien Tinh; Ringwald, Pascal; Bethell, Delia; Nosten, Francois; Phyo, Aung Pyae; Pukrittayakamee, Sasithon; Chotivanich, Kesinee; Chuor, Char Meng; Nguon, Chea; Suon, Seila; Sreng, Sokunthea; Newton, Paul N; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Htut, Ye; Han, Kay Thwe; Kyaw, Myat Phone; Faiz, Md Abul; Fanello, Caterina I; Onyamboko, Marie; Mokuolu, Olugbenga A; Jacob, Christopher G; Takala-Harrison, Shannon; Plowe, Christopher V; Day, Nicholas P; Dondorp, Arjen M; Spencer, Chris C A; McVean, Gilean; Fairhurst, Rick M; White, Nicholas J; Kwiatkowski, Dominic P

    2015-01-01

    We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population. PMID:25599401

  5. Binding and inhibition of drug transport proteins by heparin: a potential drug transporter modulator capable of reducing multidrug resistance in human cancer cells.

    PubMed

    Chen, Yunliang; Scully, Michael; Petralia, Gloria; Kakkar, Ajay

    2014-01-01

    A major problem in cancer treatment is the development of resistance to chemotherapeutic agents, multidrug resistance (MDR), associated with increased activity of transmembrane drug transporter proteins which impair cytotoxic treatment by rapidly removing the drugs from the targeted cells. Previously, it has been shown that heparin treatment of cancer patients undergoing chemotherapy increases survival. In order to determine whether heparin is capable reducing MDR and increasing the potency of chemotherapeutic drugs, the cytoxicity of a number of agents toward four cancer cell lines (a human enriched breast cancer stem cell line, two human breast cancer cell lines, MCF-7 and MDA-MB-231, and a human lung cancer cell line A549) was tested in the presence or absence of heparin. Results demonstrated that heparin increased the cytotoxicity of a range of chemotherapeutic agents. This effect was associated with the ability of heparin to bind to several of the drug transport proteins of the ABC and non ABC transporter systems. Among the ABC system, heparin treatment caused significant inhibition of the ATPase activity of ABCG2 and ABCC1, and of the efflux function observed as enhanced intracellular accumulation of specific substrates. Doxorubicin cytoxicity, which was enhanced by heparin treatment of MCF-7 cells, was found to be under the control of one of the major non-ABC transporter proteins, lung resistance protein (LRP). LRP was also shown to be a heparin-binding protein. These findings indicate that heparin has a potential role in the clinic as a drug transporter modulator to reduce multidrug resistance in cancer patients. PMID:24253450

  6. Microarray-based detection and expression analysis of ABC and SLC transporters in drug-resistant ovarian cancer cell lines.

    PubMed

    Januchowski, Radosław; Zawierucha, Piotr; Andrzejewska, Małgorzata; Ruciński, Marcin; Zabel, Maciej

    2013-04-01

    Multiple drug resistance of cancer cells is multifactorial. A microarray technique may provide information about new candidate genes playing a role in drug resistance. Drug membrane transporters from ABC and SLC families play a main role in this phenomenon. This study demonstrates alterations in ABC and SLC gene expression levels in methotrexate, cisplatin, doxorubicin, vincristine, topotecan and paclitaxel-resistant variant of W1 ovarian cancer cell line. Resistant W1 cell lines were derived by stepwise selection of cells in increasing concentration of drugs. Affymetrix GeneChip(®) Human Genome U219 Array Strip was used for hybridizations. Statistical significance was determined by independent sample t-test. The genes having altered expression levels in drug-resistant sublines were selected and filtered by scater plot. Genes up/downregulated more than threefolds were selected and listed. Among ABC genes, seven were upregulated and three were downregulated. Three genes: ABCB1, ABCB4 and ABCG2 were upregulated very significantly (over tenfold). One ABCA8 was significantly downregulated. Among 38 SLC genes, 18 were upregulated, 16 were downregulated and four were up- or downregulated dependent on the cell line. Expression of 10 SLC genes was changed very significantly (over tenfold). Four genes were significantly increased: SLC6A1, SLC9A2, SLC12A1, SLC16A6 and six genes were significantly decreased: SLC2A14, SLC7A3, SLC7A8, SLC7A11, SLC16A14, SLC38A9. Based on the expression profiles, our results provide a preliminary insight into the relationship between drug resistance and expression of membrane transporters involved in drug resistance. Correlation of specific drug transporter with drug resistance requires further analysis. PMID:23462296

  7. Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum.

    PubMed

    Bushman, Mary; Morton, Lindsay; Duah, Nancy; Quashie, Neils; Abuaku, Benjamin; Koram, Kwadwo A; Dimbu, Pedro Rafael; Plucinski, Mateusz; Gutman, Julie; Lyaruu, Peter; Kachur, S Patrick; de Roode, Jacobus C; Udhayakumar, Venkatachalam

    2016-03-16

    Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures. PMID:26984625

  8. SKELETAL MUSCLE SODIUM GLUCOSE CO-TRANSPORTERS IN OLDER ADULTS WITH TYPE 2 DIABETES UNDERGOING RESISTANCE TRAINING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the expression of the sodium-dependent glucose co-transporter system (SGLT3) in skeletal muscle of Hispanic older adults with type 2 diabetes. Subjects (65+/-8 yr) were randomized to resistance training (3x/wk, n=13) or standard of care (controls, n=5) for 16 weeks. Skeletal muscle SGL...

  9. Title A de novo synthesis citrate transporter VuMATE confers aluminum resistance in rice bean (vigna umbellata)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Al-activated organic acid anion efflux from roots is an important Al resistance mechanism in plants. We have conducted the homologous cloning and isolation of VuMATE (Vigna umbellata multidrug and toxic compound extrusion), a gene encoding a de novo citrate transporter from rice bean. Al treatment u...

  10. The cellular uptake mechanism, intracellular transportation, and exocytosis of polyamidoamine dendrimers in multidrug-resistant breast cancer cells

    PubMed Central

    Zhang, Jie; Liu, Dan; Zhang, Mengjun; Sun, Yuqi; Zhang, Xiaojun; Guan, Guannan; Zhao, Xiuli; Qiao, Mingxi; Chen, Dawei; Hu, Haiyang

    2016-01-01

    Polyamidoamine dendrimers, which can deliver drugs and genetic materials to resistant cells, are attracting increased research attention, but their transportation behavior in resistant cells remains unclear. In this paper, we performed a systematic analysis of the cellular uptake, intracellular transportation, and efflux of PAMAM-NH2 dendrimers in multidrug-resistant breast cancer cells (MCF-7/ADR cells) using sensitive breast cancer cells (MCF-7 cells) as the control. We found that the uptake rate of PAMAM-NH2 was much lower and exocytosis of PAMAM-NH2 was much greater in MCF-7/ADR cells than in MCF-7 cells due to the elimination of PAMAM-NH2 from P-glycoprotein and the multidrug resistance-associated protein in MCF-7/ADR cells. Macropinocytosis played a more important role in its uptake in MCF-7/ADR cells than in MCF-7 cells. PAMAM-NH2 aggregated and became more degraded in the lysosomal vesicles of the MCF-7/ADR cells than in those of the MCF-7 cells. The endoplasmic reticulum and Golgi complex were found to participate in the exocytosis rather than endocytosis process of PAMAM-NH2 in both types of cells. Our findings clearly showed the intracellular transportation process of PAMAM-NH2 in MCF-7/ADR cells and provided a guide of using PAMAM-NH2 as a drug and gene vector in resistant cells. PMID:27536106

  11. The cellular uptake mechanism, intracellular transportation, and exocytosis of polyamidoamine dendrimers in multidrug-resistant breast cancer cells.

    PubMed

    Zhang, Jie; Liu, Dan; Zhang, Mengjun; Sun, Yuqi; Zhang, Xiaojun; Guan, Guannan; Zhao, Xiuli; Qiao, Mingxi; Chen, Dawei; Hu, Haiyang

    2016-01-01

    Polyamidoamine dendrimers, which can deliver drugs and genetic materials to resistant cells, are attracting increased research attention, but their transportation behavior in resistant cells remains unclear. In this paper, we performed a systematic analysis of the cellular uptake, intracellular transportation, and efflux of PAMAM-NH2 dendrimers in multidrug-resistant breast cancer cells (MCF-7/ADR cells) using sensitive breast cancer cells (MCF-7 cells) as the control. We found that the uptake rate of PAMAM-NH2 was much lower and exocytosis of PAMAM-NH2 was much greater in MCF-7/ADR cells than in MCF-7 cells due to the elimination of PAMAM-NH2 from P-glycoprotein and the multidrug resistance-associated protein in MCF-7/ADR cells. Macropinocytosis played a more important role in its uptake in MCF-7/ADR cells than in MCF-7 cells. PAMAM-NH2 aggregated and became more degraded in the lysosomal vesicles of the MCF-7/ADR cells than in those of the MCF-7 cells. The endoplasmic reticulum and Golgi complex were found to participate in the exocytosis rather than endocytosis process of PAMAM-NH2 in both types of cells. Our findings clearly showed the intracellular transportation process of PAMAM-NH2 in MCF-7/ADR cells and provided a guide of using PAMAM-NH2 as a drug and gene vector in resistant cells. PMID:27536106

  12. Prolonged neuropsychiatric effects following management of chloroquine intoxication with psychotropic polypharmacy

    PubMed Central

    Maxwell, Nicole M; Nevin, Remington L; Stahl, Stephen; Block, Jerald; Shugarts, Sarah; Wu, Alan H B; Dominy, Stephen; Solano-Blanco, Miguel Alonso; Kappelman-Culver, Sharon; Lee-Messer, Christopher; Maldonado, Jose; Maxwell, Andrew J

    2015-01-01

    Key Clinical Message Susceptibility to quinoline antimalarial intoxication may reflect individual genetic and drug-induced variation in neuropharmacokinetics. In this report, we describe a case of chloroquine intoxication that appeared to be prolonged by subsequent use of multiple psychotropic medications. This case highlights important new considerations for the management of quinoline antimalarial intoxication. PMID:26185633

  13. N'Dribala (Cochlospermum planchonii) versus chloroquine for treatment of uncomplicated Plasmodium falciparum malaria.

    PubMed

    Benoit-Vical, F; Valentin, A; Da, B; Dakuyo, Z; Descamps, L; Mallié, M

    2003-11-01

    The aim of this work was to assess the efficacy of oral N'Dribala (tuberous roots decoction of Cochlospermum planchonii Hook) treatment versus chloroquine in non-severe malaria. The study included 85 patients with uncomplicated Plasmodium falciparum infection in Banfora, Burkina Faso. Forty-six patients that received N'Dribala beverage were compared to 21 patients treated with chloroquine. All patients were monitored with clinical examination and a parasitemia control by Giemsa-stained thick films. N'Dribala appeared safe and statistically as efficient as chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria. At day 5 (D5), 57% of chloroquine-treated and 52% of N'Dribala-treated patients were cured with no detectable parasitemia (parasite density (Pd): 0) and more than 90% of whole patients were asymptomatic. N'Dribala is easily available in this country, cheap, without significant side effects and efficient with a clearly demonstrated activity on Plasmodium falciparum blood stages. This study enhances the traditional use of the Cochlospermum planchonii as alternative therapy for treatment of non-severe malaria. PMID:14522441

  14. Chloroquine alleviates etoposide-induced centrosome amplification by inhibiting CDK2 in adrenocortical tumor cells

    PubMed Central

    Chen, T-Y; Syu, J-S; Lin, T-C; Cheng, H-l; Lu, F-l; Wang, C-Y

    2015-01-01

    The antitumor drug etoposide (ETO) is widely used in treating several cancers, including adrenocortical tumor (ACT). However, when used at sublethal doses, tumor cells still survive and are more susceptible to the recurring tumor due to centrosome amplification. Here, we checked the effect of sublethal dose of ETO in ACT cells. Sublethal dose of ETO treatment did not induce cell death but arrested the ACT cells in G2/M phase. This resulted in centrosome amplification and aberrant mitotic spindle formation leading to genomic instability and cellular senescence. Under such conditions, Chk2, cyclin A/CDK2 and ERK1/2 were aberrantly activated. Pharmacological inactivation of Chk2, CDK2 or ERK1/2 or depletion of CDK2 or Chk2 inhibited the centrosome amplification in ETO-treated ACT cells. In addition, autophagy was activated by ETO and was required for ACT cell survival. Chloroquine, the autophagy inhibitor, reduced ACT cell growth and inhibited ETO-induced centrosome amplification. Chloroquine alleviated CDK2 and ERK, but not Chk2, activation and thus inhibited centrosome amplification in either ETO- or hydroxyurea-treated ACT cells. In addition, chloroquine also inhibited centrosome amplification in osteosarcoma U2OS cell lines when treated with ETO or hydroxyurea. In summary, we have demonstrated that chloroquine inhibited ACT cell growth and alleviated DNA damage-induced centrosome amplification by inhibiting CDK2 and ERK activity, thus preventing genomic instability and recurrence of ACT. PMID:26690546

  15. Chitosan conjugated chloroquine: proficient to protect the induction of liver apoptosis during malaria.

    PubMed

    Tripathy, Satyajit; Chattopadhyay, Sourav; Dash, Sandeep Kumar; Chowdhuri, Angshuman Ray; Das, Sabyasachi; Sahu, Sumanta Kumar; Majumdar, Subrata; Roy, Somenath

    2015-03-01

    Chitosan has impelled continuous motion by its unique physicochemical and biological characteristics. In our study, chitosan-tripolyphosphate (CS-TPP) particles was conjugated with an undervalued antimalarial drug, chloroquine to find out the proficiency against ROS mediated caspase activation and apoptosis in liver during Plasmodium berghei NK65 infection. The transmission electron microscopic image illustrated the size range of particle was less than 50 nm and the particle showed the blood compatibility. ROS generation, mitochondrial membrane potential, anti apoptotic and pro apoptotic protein level of CS-TPP conjugated chloroquine treated group revealed that CS-TPP conjugation amplified the protective capability of chloroquine. FACS study by annexin v-FITC and PI staining reveals chloroquine treatment reduces significantly (P<0.05) the apoptotic cells by 25.31%; whereas chitosan-tripolyphosphate conjugated nanochloroquine decreases by 61.56% apoptotic cell against P. berghei induced liver apoptosis. This study suggests that proficiency of conventional antimalarial drug may escalate by delivery with chitosan nanoparticles to portray defense possessions against malarial damage. PMID:25542171

  16. Expression of Plasmodium vivax crt-o Is Related to Parasite Stage but Not Ex Vivo Chloroquine Susceptibility.

    PubMed

    Pava, Zuleima; Handayuni, Irene; Wirjanata, Grennady; To, Sheren; Trianty, Leily; Noviyanti, Rintis; Poespoprodjo, Jeanne Rini; Auburn, Sarah; Price, Ric N; Marfurt, Jutta

    2016-01-01

    Chloroquine (CQ)-resistant Plasmodium vivax is present in most countries where P. vivax infection is endemic, but the underlying molecular mechanisms responsible remain unknown. Increased expression of P. vivax crt-o (pvcrt-o) has been correlated with in vivo CQ resistance in an area with low-grade resistance. We assessed pvcrt-o expression in isolates from Papua (Indonesia), where P. vivax is highly CQ resistant. Ex vivo drug susceptibilities to CQ, amodiaquine, piperaquine, mefloquine, and artesunate were determined using a modified schizont maturation assay. Expression levels of pvcrt-o were measured using a novel real-time quantitative reverse transcription-PCR method. Large variations in pvcrt-o expression were observed across the 51 isolates evaluated, with the fold change in expression level ranging from 0.01 to 59 relative to that seen with the P. vivax β-tubulin gene and from 0.01 to 24 relative to that seen with the P. vivax aldolase gene. Expression was significantly higher in isolates with the majority of parasites at the ring stage of development (median fold change, 1.7) compared to those at the trophozoite stage (median fold change, 0.5; P < 0.001). Twenty-nine isolates fulfilled the criteria for ex vivo drug susceptibility testing and showed high variability in CQ responses (median, 107.9 [range, 6.5 to 345.7] nM). After controlling for the parasite stage, we found that pvcrt-o expression levels did not correlate with the ex vivo response to CQ or with that to any of the other antimalarials tested. Our results highlight the importance of development-stage composition for measuring pvcrt-o expression and suggest that pvcrt-o transcription is not a primary determinant of ex vivo drug susceptibility. A comprehensive transcriptomic approach is warranted for an in-depth investigation of the role of gene expression levels and P. vivax drug resistance. PMID:26525783

  17. Expression of Plasmodium vivax crt-o Is Related to Parasite Stage but Not Ex Vivo Chloroquine Susceptibility

    PubMed Central

    Pava, Zuleima; Handayuni, Irene; Wirjanata, Grennady; To, Sheren; Trianty, Leily; Noviyanti, Rintis; Poespoprodjo, Jeanne Rini; Auburn, Sarah; Price, Ric N.

    2015-01-01

    Chloroquine (CQ)-resistant Plasmodium vivax is present in most countries where P. vivax infection is endemic, but the underlying molecular mechanisms responsible remain unknown. Increased expression of P. vivax crt-o (pvcrt-o) has been correlated with in vivo CQ resistance in an area with low-grade resistance. We assessed pvcrt-o expression in isolates from Papua (Indonesia), where P. vivax is highly CQ resistant. Ex vivo drug susceptibilities to CQ, amodiaquine, piperaquine, mefloquine, and artesunate were determined using a modified schizont maturation assay. Expression levels of pvcrt-o were measured using a novel real-time quantitative reverse transcription-PCR method. Large variations in pvcrt-o expression were observed across the 51 isolates evaluated, with the fold change in expression level ranging from 0.01 to 59 relative to that seen with the P. vivax β-tubulin gene and from 0.01 to 24 relative to that seen with the P. vivax aldolase gene. Expression was significantly higher in isolates with the majority of parasites at the ring stage of development (median fold change, 1.7) compared to those at the trophozoite stage (median fold change, 0.5; P < 0.001). Twenty-nine isolates fulfilled the criteria for ex vivo drug susceptibility testing and showed high variability in CQ responses (median, 107.9 [range, 6.5 to 345.7] nM). After controlling for the parasite stage, we found that pvcrt-o expression levels did not correlate with the ex vivo response to CQ or with that to any of the other antimalarials tested. Our results highlight the importance of development-stage composition for measuring pvcrt-o expression and suggest that pvcrt-o transcription is not a primary determinant of ex vivo drug susceptibility. A comprehensive transcriptomic approach is warranted for an in-depth investigation of the role of gene expression levels and P. vivax drug resistance. PMID:26525783

  18. Phenotypic reversal of the btn1 defects in yeast by chloroquine: a yeast model for Batten disease.

    PubMed

    Pearce, D A; Carr, C J; Das, B; Sherman, F

    1999-09-28

    BTN1 of Saccharomyces cerevisiae encodes an ortholog of CLN3, the human Batten disease gene. We have reported previously that deletion of BTN1, btn1-Delta, resulted in a pH-dependent resistance to D-(-)-threo-2-amino-1-[p-nitrophenyl]-1,3-propanediol (ANP). This phenotype was caused by btn1-Delta strains having an elevated ability to acidify growth medium through an elevated activity of the plasma membrane H(+)-ATPase, resulting from a decreased vacuolar pH during early growth. We have determined that growing btn1-Delta strains in the presence of chloroquine reverses the resistance to ANP, decreases the rate of medium acidification, decreases the activity of plasma membrane H(+)-ATPase, and elevates vacuolar pH. However, an additional effect of this phenotypic reversal is that activity of plasma membrane H(+)-ATPase is decreased further and vacuolar pH is increased further as btn1-Delta strains continue to grow. This phenotypic reversal of btn1-Delta can be considered for developing a therapy for Batten disease. PMID:10500178

  19. Ex Vivo Activity of Endoperoxide Antimalarials, Including Artemisone and Arterolane, against Multidrug-Resistant Plasmodium falciparum Isolates from Cambodia

    PubMed Central

    Chaorattanakawee, Suwanna; Lon, Chanthap; Saunders, David L.; Rutvisuttinunt, Wiriya; Yingyuen, Kritsanai; Bathurst, Ian; Ding, Xavier C.; Tyner, Stuart D.

    2014-01-01

    Novel synthetic endoperoxides are being evaluated as new components of artemisinin combination therapies (ACTs) to treat artemisinin-resistant Plasmodium falciparum malaria. We conducted blinded ex vivo activity testing of fully synthetic (OZ78 and OZ277) and semisynthetic (artemisone, artemiside, artesunate, and dihydroartemisinin) endoperoxides in the histidine-rich protein 2 enzyme-linked immunosorbent assay against 200 P. falciparum isolates from areas of artemisinin-resistant malaria in western and northern Cambodia in 2009 and 2010. The order of potency and geometric mean (GM) 50% inhibitory concentrations (IC50s) were as follows: artemisone (2.40 nM) > artesunate (8.49 nM) > dihydroartemisinin (11.26 nM) > artemiside (15.28 nM) > OZ277 (31.25 nM) > OZ78 (755.27 nM). Ex vivo activities of test endoperoxides positively correlated with dihydroartemisinin and artesunate. The isolates were over 2-fold less susceptible to dihydroartemisinin than the artemisinin-sensitive P. falciparum W2 clone and showed sensitivity comparable to those with test endoperoxides and artesunate, with isolate/W2 IC50 susceptibility ratios of <2.0. All isolates had P. falciparum chloroquine resistance transporter mutations, with negative correlations in sensitivity to endoperoxides and chloroquine. The activities of endoperoxides (artesunate, dihydroartemisinin, OZ277, and artemisone) significantly correlated with that of the ACT partner drug, mefloquine. Isolates had mutations associated with clinical resistance to mefloquine, with 35% prevalence of P. falciparum multidrug resistance gene 1 (pfmdr1) amplification and 84.5% occurrence of the pfmdr1 Y184F mutation. GM IC50s for mefloquine, lumefantrine, and endoperoxides (artesunate, dihydroartemisinin, OZ277, OZ78, and artemisone) correlated with pfmdr1 copy number. Given that current ACTs are failing potentially from reduced sensitivity to artemisinins and partner drugs, newly identified mutations associated with artemisinin resistance

  20. Dynamic Resistance of YBCO-Coated Conductors in Applied AC Fields with DC Transport Currents and DC Background Fields

    SciTech Connect

    Duckworth, Robert C; Zhang, Yifei; Ha, Tam T; Gouge, Michael J

    2011-01-01

    In order to predict heat loads in future saturable core fault-current-limiting devices due to ac fringing fields, dynamic resistance in YBCO-coated conductors was measured at 77 K in peak ac fields up to 25 mT at 60 Hz and in dc fields up to 1 T. With the sample orientation set such that the conductor face was either parallel or perpendicular to the ac and dc applied fields, the dynamic resistance was measured at different fractions of the critical current to determine the relationship between the dc transport current and the applied fields. With respect to field orientation, the dynamic resistance for ac fields that were perpendicular to the conductor face was significantly higher than when the ac fields were parallel to the conductor face. It was also observed that the dynamic resistance: (1) increased with increasing fraction of the dc transport current to the critical current, (2) was proportional to the inverse of the critical current, and (3) demonstrated a linear dependence with the applied ac field once a threshold field was exceeded. This functional behavior was consistent with a critical state model for the dynamic resistance, but discrepancies in absolute value of the dynamic resistance suggested that further theoretical development is needed.

  1. Synergistic killing effect of chloroquine and androgen deprivation in LNCaP cells

    SciTech Connect

    Kaini, Ramesh R.; Hu, Chien-An A.

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Chloroquine synergistically killed LNCaP cells during androgen deprivation treatment. Black-Right-Pointing-Pointer Chloroquine inhibited the function of autolysosomes and decreases the cytosolic ATP. Black-Right-Pointing-Pointer Chloroquine induced nuclear and DNA fragmentation in androgen deprived LNCaP. Black-Right-Pointing-Pointer Chloroquine may be an useful adjuvant in hormone ablation therapy in PCa patients. -- Abstract: Modulation of autophagy is a new paradigm in cancer therapeutics. Recently a novel function of chloroquine (CLQ) in inhibiting degradation of autophagic vesicles has been revealed, which raises the question whether CLQ can be used as an adjuvant in targeting autophagic pro-survival mechanism in prostate cancer (PCa). We previously showed that autophagy played a protective role during hormone ablation therapy, in part, by consuming lipid droplets in PCa cells. In addition, blocking autophagy by genetic and pharmacological means in the presence of androgen deprivation caused cell death in PCa cells. To further investigate the importance of autophagy in PCa survival and dissect the role of CLQ in PCa death, we treated hormone responsive LNCaP cells with CLQ in combination with androgen deprivation. We observed that CLQ synergistically killed LNCaP cells during androgen deprivation in a dose- and time-dependent manner. We further confirmed that CLQ inhibited the maturation of autophagic vesicles and decreased the cytosolic ATP. Moreover, CLQ induced nuclear condensation and DNA fragmentation, a hallmark of apoptosis, in androgen deprived LNCaP cells. Taken together, our finding suggests that CLQ may be an useful adjuvant in hormone ablation therapy to improve the therapeutic efficacy.

  2. Possible involvement of nitrergic and opioidergic systems in the modulatory effect of acute chloroquine treatment on pentylenetetrazol induced convulsions in mice.

    PubMed

    Hassanipour, Mahsa; Shirzadian, Armin; Boojar, Mahdi Mashhadi-Akbar; Abkhoo, Aminreza; Abkhoo, Alireza; Delazar, Sina; Amiri, Shayan; Rahimi, Nastaran; Ostadhadi, Sattar; Dehpour, Ahmad-Reza

    2016-03-01

    Chloroquine has long been used for the treatment of malaria and rheumatological disorders. Accumulating evidence suggests potential use of chloroquine as a neuroprotective agent. Several studies have reported that endogenous opioids and nitric oxide (NO) system mediate the chloroquine effects. In the present study, the involvements of endogenous opioids and NO in the modulatory effects of chloroquine on pentylenetetrazol-induced seizures were assessed in mice. Chloroquine 5mg/kg significantly increased the seizure threshold, but this effect was reversed with naltrexone 1mg/kg. Acute co-administration of l-NAME (non-selective NO synthase (NOS) inhibitor, 5mg/kg) or 7-NI (selective neuronal NOS inhibitor, 40mg/kg) with the effective dose of chloroquine completely inhibited its anticonvulsant effects. Acute single injection of a sub-effective dose of l-arginine (NO precursor, 60mg/kg) with a sub-effective dose of chloroquine 2.5mg/kg increased the seizure threshold but administration of l-arginine 60mg/kg with chloroquine 10mg/kg decreased the seizure threshold. Moreover, the combination of the lower doses of naltrexone (0.1mg/kg) and 7-NI (15mg/kg) showed additive effects in blocking the chloroquine-induced anticonvulsant properties. Chloroquine 5mg/kg enhanced the hippocampal nitrite levels. Chloroquine at the dose of 20mg/kg decreased the seizure threshold. This effect was inhibited through l-NAME (5mg/kg), 7-NI (40mg/kg) and naltrexone (1mg/kg) administration with this dose of chloroquine. In conclusion, NO signaling probably through neuronal NOS, but not inducible NOS could be involved in the opioid-dependent anticonvulsant effects of chloroquine in this model of seizures in mice. It seems that nitric oxide and opioid systems are involved in modulatory effect of chloroquine on seizures induced by pentylenetetrazol. PMID:26655695

  3. Secondary Metabolites from Plants Inhibiting ABC Transporters and Reversing Resistance of Cancer Cells and Microbes to Cytotoxic and Antimicrobial Agents

    PubMed Central

    Wink, Michael; Ashour, Mohamed L.; El-Readi, Mahmoud Zaki

    2012-01-01

    Fungal, bacterial, and cancer cells can develop resistance against antifungal, antibacterial, or anticancer agents. Mechanisms of resistance are complex and often multifactorial. Mechanisms include: (1) Activation of ATP-binding cassette (ABC) transporters, such as P-gp, which pump out lipophilic compounds that have entered a cell, (2) Activation of cytochrome p450 oxidases which can oxidize lipophilic agents to make them more hydrophilic and accessible for conjugation reaction with glucuronic acid, sulfate, or amino acids, and (3) Activation of glutathione transferase, which can conjugate xenobiotics. This review summarizes the evidence that secondary metabolites (SM) of plants, such as alkaloids, phenolics, and terpenoids can interfere with ABC transporters in cancer cells, parasites, bacteria, and fungi. Among the active natural products several lipophilic terpenoids [monoterpenes, diterpenes, triterpenes (including saponins), steroids (including cardiac glycosides), and tetraterpenes] but also some alkaloids (isoquinoline, protoberberine, quinoline, indole, monoterpene indole, and steroidal alkaloids) function probably as competitive inhibitors of P-gp, multiple resistance-associated protein 1, and Breast cancer resistance protein in cancer cells, or efflux pumps in bacteria (NorA) and fungi. More polar phenolics (phenolic acids, flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, tannins, anthraquinones, and naphthoquinones) directly inhibit proteins forming several hydrogen and ionic bonds and thus disturbing the 3D structure of the transporters. The natural products may be interesting in medicine or agriculture as they can enhance the activity of active chemotherapeutics or pesticides or even reverse multidrug resistance, at least partially, of adapted and resistant cells. If these SM are applied in combination with a cytotoxic or antimicrobial agent, they may reverse resistance in a synergistic fashion. PMID:22536197

  4. Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein.

    PubMed

    Tay, Wee Tek; Mahon, Rod J; Heckel, David G; Walsh, Thomas K; Downes, Sharon; James, William J; Lee, Sui-Fai; Reineke, Annette; Williams, Adam K; Gordon, Karl H J

    2015-11-01

    The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests) to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC) marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC) transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the detailed mode

  5. Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein

    PubMed Central

    Tay, Wee Tek; Mahon, Rod J.; Heckel, David G.; Walsh, Thomas K.; Downes, Sharon; James, William J.; Lee, Sui-Fai; Reineke, Annette; Williams, Adam K.; Gordon, Karl H. J.

    2015-01-01

    The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests) to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC) marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC) transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the detailed mode

  6. Experiments on the resistance of a large transport vessel navigating in the Arctic region in pack ice conditions

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Li, Wei; Wang, Yinghui; Wu, Baoshan

    2016-07-01

    In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

  7. Vital and dispensable roles of Plasmodium multidrug resistance transporters during blood- and mosquito-stage development.

    PubMed

    Rijpma, Sanna R; van der Velden, Maarten; Annoura, Takeshi; Matz, Joachim M; Kenthirapalan, Sanketha; Kooij, Taco W A; Matuschewski, Kai; van Gemert, Geert-Jan; van de Vegte-Bolmer, Marga; Siebelink-Stoter, Rianne; Graumans, Wouter; Ramesar, Jai; Klop, Onny; Russel, Frans G M; Sauerwein, Robert W; Janse, Chris J; Franke-Fayard, Blandine M; Koenderink, Jan B

    2016-07-01

    Multidrug resistance (MDR) proteins belong to the B subfamily of the ATP Binding Cassette (ABC) transporters, which export a wide range of compounds including pharmaceuticals. In this study, we used reverse genetics to study the role of all seven Plasmodium MDR proteins during the life cycle of malaria parasites. Four P. berghei genes (encoding MDR1, 4, 6 and 7) were refractory to deletion, indicating a vital role during blood stage multiplication and validating them as potential targets for antimalarial drugs. Mutants lacking expression of MDR2, MDR3 and MDR5 were generated in both P. berghei and P. falciparum, indicating a dispensable role for blood stage development. Whereas P. berghei mutants lacking MDR3 and MDR5 had a reduced blood stage multiplication in vivo, blood stage growth of P. falciparum mutants in vitro was not significantly different. Oocyst maturation and sporozoite formation in Plasmodium mutants lacking MDR2 or MDR5 was reduced. Sporozoites of these P. berghei mutants were capable of infecting mice and life cycle completion, indicating the absence of vital roles during liver stage development. Our results demonstrate vital and dispensable roles of MDR proteins during blood stages and an important function in sporogony for MDR2 and MDR5 in both Plasmodium species. PMID:26991313

  8. Flavonoids from Eight Tropical Plant Species That Inhibit the Multidrug Resistance Transporter ABCG2

    PubMed Central

    Versiani, Muhammad Ali; Diyabalanage, Thushara; Ratnayake, Ranjala; Henrich, Curtis J.; Bates, Susan E.; McMahon, James B.; Gustafson, Kirk R.

    2013-01-01

    Overexpression of ABCG2, a membrane-bound multidrug transporter, can make tumor cells resistant to treatment with conventional chemotherapeutic agents. A high-throughput screening effort with the NCI repository of natural product extracts revealed that eight tropical plant extracts significantly inhibited the function of ABCG2. This activity was tracked throughout the extract fractionation process to a series of ABCG2 inhibitory flavonoids (1–13). Their structures were identified by a combination of NMR, mass spectrometry, and circular dichroism studies, and this resulted in the elucidation of (2S)-5,7,3′-trihydroxy-4′-methoxy-8-(3″-methylbut-2″-enyl)-flavonone (1), (2S)-5,7,3′,5′-tetrahydroxy-8-[3″,8″ -dimethylocta-2″(E),7″-dienyl]flavonone (3), and 5,7,3′-trihydroxy-3,5′-dimethoxy-2′-(3′-methylbut-2-enyl)flavone (12) as new compounds. PMID:21275386

  9. Transport and persistence of tylosin-resistant enterococci, erm genes, and tylosin in soil and drainage water from fields receiving swine manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land application of manure from tylosin-treated swine introduces tylosin-resistant enterococci, erm genes, which confer resistance to tylosin, and tylosin. This study documents the occurrence and transport of tylosin-resistant enterococci, erm genes, and tylosin in tile-drained chisel plow and no-ti...

  10. Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure.

    PubMed

    Luby, Elizabeth M; Moorman, Thomas B; Soupir, Michelle L

    2016-04-15

    Application of manure from swine treated with antibiotics introduces antibiotics and antibiotic resistance genes to soil with the potential for further movement in drainage water, which may contribute to the increase in antibiotic resistance in non-agricultural settings. We compared losses of antibiotic-resistant Enterococcus and macrolide-resistance (erm and msrA) genes in water draining from plots with or without swine manure application under chisel plow and no till conditions. Concentrations of ermB, ermC and ermF were all >10(9)copies g(-1) in manure from tylosin-treated swine, and application of this manure resulted in short-term increases in the abundance of these genes in soil. Abundances of ermB, ermC and ermF in manured soil returned to levels identified in non-manured control plots by the spring following manure application. Tillage practices yielded no significant differences (p>0.10) in enterococci or erm gene concentrations in drainage water and were therefore combined for further analysis. While enterococci and tylosin-resistant enterococci concentrations in drainage water showed no effects of manure application, ermB and ermF concentrations in drainage water from manured plots were significantly higher (p<0.01) than concentrations coming from non-manured plots. ErmB and ermF were detected in 78% and 44%, respectively, of water samples draining from plots receiving manure. Although ermC had the highest concentrations of the three genes in drainage water, there was no effect of manure application on ermC abundance. MsrA was not detected in manure, soil or water. This study is the first to report significant increases in abundance of resistance genes in waters draining from agricultural land due to manure application. PMID:26874610

  11. shRNA library screening identifies nucleocytoplasmic transport as a mediator of BCR-ABL1 kinase-independent resistance.

    PubMed

    Khorashad, Jamshid S; Eiring, Anna M; Mason, Clinton C; Gantz, Kevin C; Bowler, Amber D; Redwine, Hannah M; Yu, Fan; Kraft, Ira L; Pomicter, Anthony D; Reynolds, Kimberly R; Iovino, Anthony J; Zabriskie, Matthew S; Heaton, William L; Tantravahi, Srinivas K; Kauffman, Michael; Shacham, Sharon; Chenchik, Alex; Bonneau, Kyle; Ullman, Katharine S; O'Hare, Thomas; Deininger, Michael W

    2015-03-12

    The mechanisms underlying tyrosine kinase inhibitor (TKI) resistance in chronic myeloid leukemia (CML) patients lacking explanatory BCR-ABL1 kinase domain mutations are incompletely understood. To identify mechanisms of TKI resistance that are independent of BCR-ABL1 kinase activity, we introduced a lentiviral short hairpin RNA (shRNA) library targeting ∼5000 cell signaling genes into K562(R), a CML cell line with BCR-ABL1 kinase-independent TKI resistance expressing exclusively native BCR-ABL1. A customized algorithm identified genes whose shRNA-mediated knockdown markedly impaired growth of K562(R) cells compared with TKI-sensitive controls. Among the top candidates were 2 components of the nucleocytoplasmic transport complex, RAN and XPO1 (CRM1). shRNA-mediated RAN inhibition or treatment of cells with the XPO1 inhibitor, KPT-330 (Selinexor), increased the imatinib sensitivity of CML cell lines with kinase-independent TKI resistance. Inhibition of either RAN or XPO1 impaired colony formation of CD34(+) cells from newly diagnosed and TKI-resistant CML patients in the presence of imatinib, without effects on CD34(+) cells from normal cord blood or from a patient harboring the BCR-ABL1(T315I) mutant. These data implicate RAN in BCR-ABL1 kinase-independent imatinib resistance and show that shRNA library screens are useful to identify alternative pathways critical to drug resistance in CML. PMID:25573989

  12. 8-Prenylnaringenin is an inhibitor of multidrug resistance-associated transporters, P-glycoprotein and MRP1.

    PubMed

    Wesołowska, Olga; Wiśniewski, Jerzy; Sroda, Kamila; Krawczenko, Agnieszka; Bielawska-Pohl, Aleksandra; Paprocka, Maria; Duś, Danuta; Michalak, Krystyna

    2010-10-10

    Flavonoids with hydrophobic e.g. prenyl substituents might constitute the promising candidates for multidrug resistance (MDR) reversal agents. The interaction of 8-prenylnaringenin (8-isopentenylnaringenin), a potent phytoestrogen isolated from common hop (Humulus lupulus), with two multidrug resistance-associated ABC transporters of cancer cells, P-glycoprotein and MRP1, has been studied for the first time. Functional test based on the transport of fluorescent substrate BCECF revealed that the flavonoid strongly inhibited MRP1 transport activity in human erythrocytes (IC(50)=5.76+/-1.80muM). Expression of MDR-related transporters in drug-sensitive (LoVo) and doxorubicin-resistant (LoVo/Dx) human colon adenocarcinoma cell lines was characterized by RT-PCR and immunochemical methods and elevated expression of P-glycoprotein in resistant cells was found to be the main difference between these two cell lines. By means of flow cytometry it was shown that 8-prenylnaringenin significantly increased the accumulation of rhodamine 123 in LoVo/Dx cells. Doxorubicin accumulation in both LoVo and LoVo/Dx cells observed by confocal microscopy was also altered in the presence of 8-prenylnaringenin. However, the presence of the studied compound did not increase doxorubicin cytotoxicity to LoVo/Dx cells. It was concluded that 8-prenylnaringenin was not able to modulate MDR in human adenocarcinoma cell line in spite of the ability to inhibit both P-glycoprotein and MRP1 activities. To our best knowledge, this is the first report of 8-prenylnaringenin interaction with clinically important ABC transporters. PMID:20633549

  13. Fungicide efflux and the MgMFS1 transporter contribute to the multidrug resistance phenotype in Zymoseptoria tritici field isolates.

    PubMed

    Omrane, Selim; Sghyer, Hind; Audéon, Colette; Lanen, Catherine; Duplaix, Clémentine; Walker, Anne-Sophie; Fillinger, Sabine

    2015-08-01

    Septoria leaf blotch is mainly controlled by fungicides. Zymoseptoria tritici, which is responsible for this disease, displays strong adaptive capacity to fungicide challenge. It developed resistance to most fungicides due to target site modifications. Recently, isolated strains showed cross-resistance to fungicides with unrelated modes of action, suggesting a resistance mechanism known as multidrug resistance (MDR). We show enhanced prochloraz efflux, sensitive to the modulators amitryptiline and chlorpromazine, for two Z. tritici strains, displaying an MDR phenotype in addition to the genotypes CYP51(I381V Y461H) or CYP51(I381V ΔY459/) (G460) , respectively, hereafter named MDR6 and MDR7. Efflux was also inhibited by verapamil in the MDR7 strain. RNA sequencing lead to the identification of several transporter genes overexpressed in both MDR strains. The expression of the MgMFS1 gene was the strongest and constitutively high in MDR field strains. Its inactivation in the MDR6 strain abolished resistance to fungicides with different modes of action supporting its involvement in MDR in Z. tritici. A 519 bp insert in the MgMFS1 promoter was detected in half of the tested MDR field strains, but absent from sensitive field strains, suggesting that the insert is correlated with the observed MDR phenotype. Besides MgMfs1, other transporters and mutations may be involved in MDR in Z. tritici. PMID:25627815

  14. Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Application of manure from swine treated with antibiotics introduces antibiotics and antibiotic resistance genes to soil with the potential for further movement in drainage water. Manure concentrations for ermB, ermC and ermF were all >109 copy g-1. Manure contained 1.76 x 105 CFUg-1 enterococci w...

  15. Absolute immunoquantification of the expression of ABC transporters P-glycoprotein, breast cancer resistance protein and multidrug resistance-associated protein 2 in human liver and duodenum.

    PubMed

    Tucker, Theodora G H A; Milne, Alison M; Fournel-Gigleux, Sylvie; Fenner, Katherine S; Coughtrie, Michael W H

    2012-01-15

    The ATP-binding cassette (ABC) transporters breast cancer resistance protein (BCRP), multidrug resistance-associated protein 2 (MRP2), and P-glycoprotein (Pgp) are important in the distribution and elimination of many drugs and endogenous metabolites. Due to their membrane location and hydrophobicity it is difficult to generate purified protein standards to quantify these transporters in human tissues. The present study generated transporter proteins fused with the S-peptide of ribonuclease for use as standards in immunoquantification in human liver and small intestine. Quantification of the S•tag™, a 15 amino acid peptide, is based on the formation of a functional ribonuclease activity upon its high affinity reconstitution with ribonuclease S-protein. S-tagged transporters were used as full-length protein standards in the immunoquantification of endogenous BCRP, MRP2, and Pgp levels in 14 duodenum and 13 liver human tissue samples. Expression levels in the duodenum were 305±248 (BCRP), 66±70 (MRP2), and 275±205 (Pgp) fmoles per cm(2). Hepatic levels were 2.6±0.9 (BCRP), 19.8±10.5 (MRP2), and 26.1±10.1 (total Pgp) pmoles per g of liver. The mean hepatic scaling factor was 35.8mg crude membrane per g of liver, and the mean duodenal scaling factor was 1.3mg crude membrane per cm(2) mucosal lining. Interindividual variability was greater in duodenal samples than liver samples. It is hoped that this innovative method of quantifying these transporters (and other membrane proteins) will improve in vivo-in vitro extrapolation and in silico prediction of drug absorption and elimination, thus supporting drug development. PMID:22062654

  16. Dual role of chloroquine in liver ischemia reperfusion injury: reduction of liver damage in early phase, but aggravation in late phase.

    PubMed

    Fang, H; Liu, A; Dahmen, U; Dirsch, O

    2013-01-01

    The anti-malaria drug chloroquine is well known as autophagy inhibitor. Chloroquine has also been used as anti-inflammatory drugs to treat inflammatory diseases. We hypothesized that chloroquine could have a dual effect in liver ischemia/reperfusion (I/R) injury: chloroquine on the one hand could protect the liver against I/R injury via inhibition of inflammatory response, but on the other hand could aggravate liver I/R injury through inhibition of autophagy. Rats (n=6 per group) were pre-treated with chloroquine (60 mg/kg, i.p.) 1 h before warm ischemia, and they were continuously subjected to a daily chloroquine injection for up to 2 days. Rats were killed 0.5, 6, 24 and 48 h after reperfusion. At the early phase (i.e., 0-6 h after reperfusion), chloroquine treatment ameliorated liver I/R injury, as indicated by lower serum aminotransferase levels, lower hepatic inflammatory cytokines and fewer histopathologic changes. In contrast, chloroquine worsened liver injury at the late phase of reperfusion (i.e., 24-48 h after reperfusion). The mechanism of protective action of chloroquine appeared to involve its ability to modulate mitogen-activated protein kinase activation, reduce high-mobility group box 1 release and inflammatory cytokines production, whereas chloroquine worsened liver injury via inhibition of autophagy and induction of hepatic apoptosis at the late phase. In conclusion, chloroquine prevents ischemic liver damage at the early phase, but aggravates liver damage at the late phase in liver I/R injury. This dual role of chloroquine should be considered when using chloroquine as an inhibitor of inflammation or autophagy in I/R injury. PMID:23807223

  17. Multidrug Resistance Protein 1 (MRP1, ABCC1), a “Multitasking” ATP-binding Cassette (ABC) Transporter*

    PubMed Central

    Cole, Susan P. C.

    2014-01-01

    The multidrug resistance protein 1 (MRP1) encoded by ABCC1 was originally discovered as a cause of multidrug resistance in tumor cells. However, it is now clear that MRP1 serves a broader role than simply mediating the ATP-dependent efflux of drugs from cells. The antioxidant GSH and the pro-inflammatory cysteinyl leukotriene C4 have been identified as key physiological organic anions effluxed by MRP1, and an ever growing body of evidence indicates that additional lipid-derived mediators are also substrates of this transporter. As such, MRP1 is a multitasking transporter that likely influences the etiology and progression of a host of human diseases. PMID:25281745

  18. Platination of the copper transporter ATP7A involved in anticancer drug resistance.

    PubMed

    Calandrini, Vania; Arnesano, Fabio; Galliani, Angela; Nguyen, Trung Hai; Ippoliti, Emiliano; Carloni, Paolo; Natile, Giovanni

    2014-08-21

    The clinical efficacy of the widely used anticancer drug cisplatin is severely limited by the emergence of resistance. This is related to the drug binding to proteins such as the copper influx transporter Ctr1, the copper chaperone Atox1, and the copper pumps ATP7A and ATP7B. While the binding modes of cisplatin to the first two proteins are known, the structural determinants of platinated ATP7A/ATP7B are lacking. Here we investigate the interaction of cisplatin with the first soluble domain of ATP7A. First, we establish by ESI-MS and (1)H, (13)C, and (15)N NMR that, in solution, the adduct is a monomer in which the sulfur atoms of residues Cys19 and Cys22 are cis-coordinated to the [Pt(NH3)2](2+) moiety. Then, we carry out hybrid Car-Parrinello QM/MM simulations and computational spectroscopy calculations on a model adduct based on the NMR structure of the apo protein and featuring the experimentally determined binding mode of the metal ion. These calculations show quantitative agreement with CD spectra and (1)H, (13)C, and (15)N NMR chemical shifts, thus providing a quantitative molecular view of the 3D binding mode of cisplatin to ATP7A. Importantly, the same comparison rules out a variety of alternative models with different coordination modes, that we explored to test the robustness of the computational approach. Using this combined in silico-in vitro approach we provide here for the first time a quantitative 3D atomic view of the platinum binding to the first soluble domain of ATP7A. PMID:24983998

  19. Role of Pfmdr1 in In Vitro Plasmodium falciparum Susceptibility to Chloroquine, Quinine, Monodesethylamodiaquine, Mefloquine, Lumefantrine, and Dihydroartemisinin

    PubMed Central

    Wurtz, Nathalie; Fall, Bécaye; Pascual, Aurélie; Fall, Mansour; Baret, Eric; Camara, Cheikhou; Nakoulima, Aminata; Diatta, Bakary; Fall, Khadidiatou Ba; Mbaye, Pape Saliou; Diémé, Yaya; Bercion, Raymond; Wade, Boubacar

    2014-01-01

    The involvement of Pfmdr1 (Plasmodium falciparum multidrug resistance 1) polymorphisms in antimalarial drug resistance is still debated. Here, we evaluate the association between polymorphisms in Pfmdr1 (N86Y, Y184F, S1034C, N1042D, and D1246Y) and Pfcrt (K76T) and in vitro responses to chloroquine (CQ), mefloquine (MQ), lumefantrine (LMF), quinine (QN), monodesethylamodiaquine (MDAQ), and dihydroartemisinin (DHA) in 174 Plasmodium falciparum isolates from Dakar, Senegal. The Pfmdr1 86Y mutation was identified in 14.9% of the samples, and the 184F mutation was identified in 71.8% of the isolates. No 1034C, 1042N, or 1246Y mutations were detected. The Pfmdr1 86Y mutation was significantly associated with increased susceptibility to MDAQ (P = 0.0023), LMF (P = 0.0001), DHA (P = 0.0387), and MQ (P = 0.00002). The N86Y mutation was not associated with CQ (P = 0.214) or QN (P = 0.287) responses. The Pfmdr1 184F mutation was not associated with various susceptibility responses to the 6 antimalarial drugs (P = 0.168 for CQ, 0.778 for MDAQ, 0.324 for LMF, 0.961 for DHA, 0.084 for QN, and 0.298 for MQ). The Pfmdr1 86Y-Y184 haplotype was significantly associated with increased susceptibility to MDAQ (P = 0.0136), LMF (P = 0.0019), and MQ (P = 0.0001). The additional Pfmdr1 86Y mutation increased significantly the in vitro susceptibility to MDAQ (P < 0.0001), LMF (P < 0.0001), MQ (P < 0.0001), and QN (P = 0.0026) in wild-type Pfcrt K76 parasites. The additional Pfmdr1 86Y mutation significantly increased the in vitro susceptibility to CQ (P = 0.0179) in Pfcrt 76T CQ-resistant parasites. PMID:25199781

  20. The novel ABC transporter ABCH1 is a potential target for RNAi-based insect pest control and resistance management

    PubMed Central

    Guo, Zhaojiang; Kang, Shi; Zhu, Xun; Xia, Jixing; Wu, Qingjun; Wang, Shaoli; Xie, Wen; Zhang, Youjun

    2015-01-01

    Insect pests cause serious crop damage and develop high-level resistance to chemical insecticides and Bacillus thuringiensis (Bt) insecticidal Cry toxins. A new promising approach for controlling them and overcoming this resistance is RNA interference (RNAi). The RNAi-based insect control strategy depends on the selection of suitable target genes. In this study, we cloned and characterized a novel ABC transporter gene PxABCH1 in diamondback moth, Plutella xylostella (L.). Phylogenetic analysis showed that PxABCH1 is closely related to ABCA and ABCG subfamily members. Spatial-temporal expression detection revealed that PxABCH1 was expressed in all tissues and developmental stages, and highest expressed in head and male adult. Midgut sequence variation and expression analyses of PxABCH1 in all the susceptible and Bt-resistant P. xylostella strains and the functional analysis by sublethal RNAi demonstrated that Cry1Ac resistance was independent of this gene. Silencing of PxABCH1 by a relatively high dose of dsRNA dramatically reduced its expression and resulted in larval and pupal lethal phenotypes in both susceptible and Cry1Ac-resistant P. xylostella strains. To our knowledge, this study provides the first insight into ABCH1 in lepidopterans and reveals it as an excellent target for RNAi-based insect pest control and resistance management. PMID:26333918

  1. The novel ABC transporter ABCH1 is a potential target for RNAi-based insect pest control and resistance management.

    PubMed

    Guo, Zhaojiang; Kang, Shi; Zhu, Xun; Xia, Jixing; Wu, Qingjun; Wang, Shaoli; Xie, Wen; Zhang, Youjun

    2015-01-01

    Insect pests cause serious crop damage and develop high-level resistance to chemical insecticides and Bacillus thuringiensis (Bt) insecticidal Cry toxins. A new promising approach for controlling them and overcoming this resistance is RNA interference (RNAi). The RNAi-based insect control strategy depends on the selection of suitable target genes. In this study, we cloned and characterized a novel ABC transporter gene PxABCH1 in diamondback moth, Plutella xylostella (L.). Phylogenetic analysis showed that PxABCH1 is closely related to ABCA and ABCG subfamily members. Spatial-temporal expression detection revealed that PxABCH1 was expressed in all tissues and developmental stages, and highest expressed in head and male adult. Midgut sequence variation and expression analyses of PxABCH1 in all the susceptible and Bt-resistant P. xylostella strains and the functional analysis by sublethal RNAi demonstrated that Cry1Ac resistance was independent of this gene. Silencing of PxABCH1 by a relatively high dose of dsRNA dramatically reduced its expression and resulted in larval and pupal lethal phenotypes in both susceptible and Cry1Ac-resistant P. xylostella strains. To our knowledge, this study provides the first insight into ABCH1 in lepidopterans and reveals it as an excellent target for RNAi-based insect pest control and resistance management. PMID:26333918

  2. Different pH requirements are associated with divergent inhibitory effects of chloroquine on human and avian influenza A viruses

    PubMed Central

    Di Trani, Livia; Savarino, Andrea; Campitelli, Laura; Norelli, Sandro; Puzelli, Simona; D'Ostilio, Daniela; Vignolo, Edoardo; Donatelli, Isabella; Cassone, Antonio

    2007-01-01

    Chloroquine is a 4-aminoquinoline previously used in malaria therapy and now becoming an emerging investigational antiviral drug due to its broad spectrum of antiviral activities. To explore whether the low pH-dependency of influenza A viruses might affect the antiviral effects of chloroquine at clinically achievable concentrations, we tested the antiviral effects of this drug on selected human and avian viruses belonging to different subtypes and displaying different pH requirements. Results showed a correlation between the responses to chloroquine and NH4Cl, a lysosomotropic agent known to increase the pH of intracellular vesicles. Time-of-addition experiments showed that the inhibitory effect of chloroquine was maximal when the drug had been added at the time of infection and was lost after 2 h post-infection. This timing approximately corresponds to that of virus/cell fusion. Moreover, there was a clear correlation between the EC50 of chloroquine in vitro and the electrostatic potential of the HA subunit (HA2) mediating the virus/cell fusion process. Overall, the present study highlights the critical importance of a host cell factor such as intravesicular pH in determining the anti-influenza activity of chloroquine and other lysosomotropic agents. PMID:17477867

  3. Role of an Archaeal PitA Transporter in the Copper and Arsenic Resistance of Metallosphaera sedula, an Extreme Thermoacidophile

    PubMed Central

    McCarthy, Samuel; Ai, Chenbing; Wheaton, Garrett; Tevatia, Rahul; Eckrich, Valerie; Kelly, Robert

    2014-01-01

    Thermoacidophilic archaea, such as Metallosphaera sedula, are lithoautotrophs that occupy metal-rich environments. In previous studies, an M. sedula mutant lacking the primary copper efflux transporter, CopA, became copper sensitive. In contrast, the basis for supranormal copper resistance remained unclear in the spontaneous M. sedula mutant, CuR1. Here, transcriptomic analysis of copper-shocked cultures indicated that CuR1 had a unique regulatory response to metal challenge corresponding to the upregulation of 55 genes. Genome resequencing identified 17 confirmed mutations unique to CuR1 that were likely to change gene function. Of these, 12 mapped to genes with annotated function associated with transcription, metabolism, or transport. These mutations included 7 nonsynonymous substitutions, 4 insertions, and 1 deletion. One of the insertion mutations mapped to pseudogene Msed_1517 and extended its reading frame an additional 209 amino acids. The extended mutant allele was identified as a homolog of Pho4, a family of phosphate symporters that includes the bacterial PitA proteins. Orthologs of this allele were apparent in related extremely thermoacidophilic species, suggesting M. sedula naturally lacked this gene. Phosphate transport studies combined with physiologic analysis demonstrated M. sedula PitA was a low-affinity, high-velocity secondary transporter implicated in copper resistance and arsenate sensitivity. Genetic analysis demonstrated that spontaneous arsenate-resistant mutants derived from CuR1 all underwent mutation in pitA and nonselectively became copper sensitive. Taken together, these results point to archaeal PitA as a key requirement for the increased metal resistance of strain CuR1 and its accelerated capacity for copper bioleaching. PMID:25092032

  4. Development of mass transport resistance in poly(lactide-co-glycolide) films and particles--a mechanistic study.

    PubMed

    Fredenberg, Susanne; Jönsson, Monica; Laakso, Timo; Wahlgren, Marie; Reslow, Mats; Axelsson, Anders

    2011-05-16

    Poly(D,L-lactide-co-glycolide) (PLG) is the most frequently used biodegradable polymer in the controlled release of an encapsulated drug. The purpose of this work was to explain the surprisingly slow diffusion through this polymer, and locate the major source of mass transport resistance. Diffusion of human growth hormone (hGH) and glucose through PLG films was undetectable (using a diffusion cell), although the degraded polymer contained several times more water than polymer mass. In vitro release of hGH from PLG-coated particles also showed a surprisingly slow rate of release. Non-porous regions inside the PLG films were detected after three weeks of degradation using dextran-coupled fluorescent probes and confocal microscopy. The findings were supported by scanning electron microscopy. Diffusion through PLG films degraded for five weeks was significantly increased when the porosity of both surfaces was increased due to the presence of ZnCl(2) in the buffer the last 3 days of the degradation period. The results indicated high mass transport resistance inside the films after three weeks of degradation, and at the surfaces after five weeks of degradation. These results should also be applicable to microparticles of different sizes. Knowledge of the reason for transport resistance is important in the development of pharmaceuticals and when modifying the rate of drug release. PMID:21392561

  5. Low resistivity ZnO-GO electron transport layer based CH3NH3PbI3 solar cells

    NASA Astrophysics Data System (ADS)

    Ahmed, Muhammad Imran; Hussain, Zakir; Mujahid, Mohammad; Khan, Ahmed Nawaz; Javaid, Syed Saad; Habib, Amir

    2016-06-01

    Perovskite based solar cells have demonstrated impressive performances. Controlled environment synthesis and expensive hole transport material impede their potential commercialization. We report ambient air synthesis of hole transport layer free devices using ZnO-GO as electron selective contacts. Solar cells fabricated with hole transport layer free architecture under ambient air conditions with ZnO as electron selective contact achieved an efficiency of 3.02%. We have demonstrated that by incorporating GO in ZnO matrix, low resistivity electron selective contacts, critical to improve the performance, can be achieved. We could achieve max efficiency of 4.52% with our completed devices for ZnO: GO composite. Impedance spectroscopy confirmed the decrease in series resistance and an increase in recombination resistance with inclusion of GO in ZnO matrix. Effect of temperature on completed devices was investigated by recording impedance spectra at 40 and 60 oC, providing indirect evidence of the performance of solar cells at elevated temperatures.

  6. Nuclear receptors in the multidrug resistance through the regulation of drug-metabolizing enzymes and drug transporters

    PubMed Central

    CHEN, Yakun; TANG, Yong; GUO, Changxiong; WANG, Jiuhui; BORAL, Debasish; NIE, Daotai

    2012-01-01

    Chemotherapy is one of the three most common treatment modalities for cancer. However, its efficacy is limited by multidrug resistant cancer cells. Drug metabolizing enzymes (DMEs) and efflux transporters promote the metabolism, elimination, and detoxification of chemotherapeutic agents. Consequently, elevated levels of DMEs and efflux transporters reduce the therapeutic effectiveness of chemotheraputics and, often, lead to treatment failure. Nuclear receptors, especially pregnane X receptor (PXR, NR1I2) and constitutive androstane activated receptor (CAR, NR1I3), are increasingly recognized for their role in xenobiotic metabolism and clearance as well as their role in the development of multidrug resistance (MDR) during chemotherapy. Promiscuous xenobiotic receptors, including PXR and CAR, govern the inducible expressions of a broad spectrum of target genes that encode phase I DMEs, phase II DMEs, and efflux transporters. Recent studies conducted by a number of groups, including ours, have revealed that PXR and CAR play pivotal roles in the development of MDR in various human carcinomas, including prostate, colon, ovarian, and esophageal squamous cell carcinomas. Accordingly, PXR/CAR expression levels and/or activation statuses may predict prognosis and identify the risk of drug resistance in patients subjected to chemotherapy. Further, PXR/CAR antagonists, when used in combination with existing chemotherapeutics that activate PXR/CAR, are feasible and promising options that could be utilized to overcome or, at least, attenuate MDR in cancer cells. PMID:22326308

  7. Cell differentiation and infectivity of Leishmania mexicana are inhibited in a strain resistant to an ABC-transporter blocker.

    PubMed

    Silva, N; Camacho, N; Figarella, K; Ponte-Sucre, A

    2004-06-01

    We analysed whether markers of cell differentiation and infectivity differed when compared to the parental sensitive strain [NR(Gs)] in an in vitro selected Leishmania strain [NR(Gr)] resistant to Glibenclamide, an ATP-binding-cassette (ABC)-transporter blocker. The data show that the cell body area was larger in NR(Gr) compared to NR(Gs) and that functional characters associated with an infective metacyclic phenotype, such as resistance to the lytic effect of the alternative complement pathway and expression of the Meta-1 protein, were reduced. The infectivity of NR(Gr) to J774.1 macrophages was also significantly reduced. These results suggest that resistance in Leishmania against Glibenclamide, a general blocker of P-glycoproteins, could produce functional modifications that may be relevant for Leishmania differentiation, infectivity and survival. PMID:15206465

  8. Dual role of LRRC8A-containing transporters on cisplatin resistance in human ovarian cancer cells.

    PubMed

    Sørensen, Belinda Halling; Dam, Celina Støving; Stürup, Stefan; Lambert, Ian Henry

    2016-07-01

    Acquired resistance to chemotherapeutic drugs in cancer cells can reflect an ability to limit cellular drug availability, to repair drug induced DNA damage, and to limit initiation/progression of cell death (apoptosis). The leucine-rich-repeat-containing 8A (LRRC8A) protein is an essential component of volume sensitive channels for organic osmolytes (VSOAC) and volume regulated anion channels (VRAC), which are activated during the apoptotic process. Here we illustrate that cisplatin resistance in human ovarian cancer cells (A2780) correlates with a reduced expression of LRRC8A and copper transporter receptor 1 (CTR1), as well as a concomitant increased expression of copper-transporting P-type ATPases (ATP7A/ATP7B). We also find that cisplatin (Pt) accumulation correlates with LRRC8A protein expression and channel activity, i.e., the cellular Pt content is high when VSOAC is activated by depolarization of the plasma membrane or hypoosmotic cell swelling, and reduced when channel activity/LRRC8A expression is reduced by genetically silencing/pharmacological inhibition, or the cells have acquired a resistant phenotype with low LRRC8A protein expression. It is suggested that reduced LRRC8A expression in cisplatin-resistant A2780 cells ensures cell survival through limitation in cisplatin accumulation and a concomitant reduction in osmolytes loss via VSOAC/VRAC and hence instigation of the apoptotic process. PMID:27112899

  9. Role of the breast cancer resistance protein (BCRP/ABCG2) in drug transport--an update.

    PubMed

    Mao, Qingcheng; Unadkat, Jashvant D

    2015-01-01

    The human breast cancer resistance protein (BCRP, gene symbol ABCG2) is an ATP-binding cassette (ABC) efflux transporter. It was so named because it was initially cloned from a multidrug-resistant breast cancer cell line where it was found to confer resistance to chemotherapeutic agents such as mitoxantrone and topotecan. Since its discovery in 1998, the substrates of BCRP have been rapidly expanding to include not only therapeutic agents but also physiological substances such as estrone-3-sulfate, 17β-estradiol 17-(β-D-glucuronide) and uric acid. Likewise, at least hundreds of BCRP inhibitors have been identified. Among normal human tissues, BCRP is highly expressed on the apical membranes of the placental syncytiotrophoblasts, the intestinal epithelium, the liver hepatocytes, the endothelial cells of brain microvessels, and the renal proximal tubular cells, contributing to the absorption, distribution, and elimination of drugs and endogenous compounds as well as tissue protection against xenobiotic exposure. As a result, BCRP has now been recognized by the FDA to be one of the key drug transporters involved in clinically relevant drug disposition. We published a highly-accessed review article on BCRP in 2005, and much progress has been made since then. In this review, we provide an update of current knowledge on basic biochemistry and pharmacological functions of BCRP as well as its relevance to drug resistance and drug disposition. PMID:25236865

  10. Hyperinsulinemia Enhances Hepatic Expression of the Fatty Acid Transporter Cd36 and Provokes Hepatosteatosis and Hepatic Insulin Resistance*

    PubMed Central

    Steneberg, Pär; Sykaras, Alexandros G.; Backlund, Fredrik; Straseviciene, Jurate; Söderström, Ingegerd; Edlund, Helena

    2015-01-01

    Hepatosteatosis is associated with the development of both hepatic insulin resistance and Type 2 diabetes. Hepatic expression of Cd36, a fatty acid transporter, is enhanced in obese and diabetic murine models and human nonalcoholic fatty liver disease, and thus it correlates with hyperinsulinemia, steatosis, and insulin resistance. Here, we have explored the effect of hyperinsulinemia on hepatic Cd36 expression, development of hepatosteatosis, insulin resistance, and dysglycemia. A 3-week sucrose-enriched diet was sufficient to provoke hyperinsulinemia, hepatosteatosis, hepatic insulin resistance, and dysglycemia in CBA/J mice. The development of hepatic steatosis and insulin resistance in CBA/J mice on a sucrose-enriched diet was paralleled by increased hepatic expression of the transcription factor Pparγ and its target gene Cd36 whereas that of genes implicated in lipogenesis, fatty acid oxidation, and VLDL secretion was unaltered. Additionally, we demonstrate that insulin, in a Pparγ-dependent manner, is sufficient to directly increase Cd36 expression in perfused livers and isolated hepatocytes. Mouse strains that display low insulin levels, i.e. C57BL6/J, and/or lack hepatic Pparγ, i.e. C3H/HeN, do not develop hepatic steatosis, insulin resistance, or dysglycemia on a sucrose-enriched diet, suggesting that elevated insulin levels, via enhanced CD36 expression, provoke fatty liver development that in turn leads to hepatic insulin resistance and dysglycemia. Thus, our data provide evidence for a direct role for hyperinsulinemia in stimulating hepatic Cd36 expression and thus the development of hepatosteatosis, hepatic insulin resistance, and dysglycemia. PMID:26085100

  11. The phytoestrogen genistein enhances multidrug resistance in breast cancer cell lines by translational regulation of ABC transporters.

    PubMed

    Rigalli, Juan Pablo; Tocchetti, Guillermo Nicolás; Arana, Maite Rocío; Villanueva, Silvina Stella Maris; Catania, Viviana Alicia; Theile, Dirk; Ruiz, María Laura; Weiss, Johanna

    2016-06-28

    Breast cancer is the most frequent malignancy in women. Multidrug resistance due to overexpression of ABC drug transporters is a common cause of chemotherapy failure and disease recurrence. Genistein (GNT) is a phytoestrogen present in soybeans and hormone supplements. We investigated the effect of GNT on the expression and function of ABC transporters in MCF-7 and MDA-MB-231 breast cancer cell lines. Results demonstrated an induction at the protein level of ABCC1 and ABCG2 and of ABCC1 in MCF-7 and MDA-MB-231, respectively. MCF-7 cells showed a concomitant increase in doxorubicin and mitoxantrone efflux and resistance, dependent on ABCG2 activity. ABCC1 induction by GNT in MDA-MB-231 cells modified neither drug efflux nor chemoresistance due to simultaneous acute inhibition of the transporter activity by GNT. All inductions took place at the translational level, as no increment in mRNA was observed and protein increase was prevented by cycloheximide. miR-181a, already demonstrated to inhibit ABCG2 translation, was down-regulated by GNT, explaining translational induction. Effects were independent of classical estrogen receptors. Results suggest potential nutrient-drug interactions that could threaten chemotherapy efficacy, especially in ABCG2-expressing tumors treated with substrates of this transporter. PMID:27033456

  12. Toward Understanding the Mechanism of Action of the Yeast Multidrug Resistance Transporter Pdr5p: A Molecular Modeling Study

    PubMed Central

    Rutledge, Robert M.; Esser, Lothar; Ma, Jichun; Xia, Di

    2010-01-01

    Pleotropic drug resistant protein 5 (Pdr5p) is a plasma membrane ATP-binding cassette (ABC) transporter and the major drug efflux pump in Saccharomyces cerevisiae. The Pdr5p family of fungal transporters possesses a number of structural features significantly different from other modeled or crystallized ABC transporters, which include a reverse topology, an atypical ATP-binding site, a very low sequence similarity in the transmembrane section and long linkers between domains. These features present a considerable hurdle in molecular modeling studies of these important transporters. Here, we report the creation of an atomic model of Pdr5p based on a combination of homology modeling and ab initio methods, incorporating information from consensus transmembrane segment prediction, residue lipophilicity, and sequence entropy. Reported mutations in the transmembrane substrate-binding pocket that altered drug-resistance were used to validate the model, and one mutation that changed the communication pattern between transmembrane and nucleotide-binding domains was used in model improvement. The predictive power of the model was demonstrated experimentally by the increased sensitivity of yeast mutants to clotrimazole having alanine substitutions for Thr1213 and Gln1253, which are predicted to be in the substrate-binding pocket, without reducing the amount of Pdr5p in the plasma membrane. The quality and reliability of our model are discussed in the context of various approaches used for modeling different parts of the structure. PMID:21034832

  13. Characterization of Cell-Type-Specific Drug Transport and Resistance of Breast Cancers Using Tumor-Microenvironment-on-Chip.

    PubMed

    Shin, Kyeonggon; Klosterhoff, Brett S; Han, Bumsoo

    2016-07-01

    Heterogeneous response and resistance of cancer cells to chemotherapeutic drugs pose a significant challenge for successful cancer treatments. In this study, an integrated experimental and theoretical analysis of cellular drug transport was developed. The experimental platform, called tumor-microenvironment-on-chip (T-MOC), is a microfluidic platform where cancer cells were cultured within a three-dimensional extracellular matrix perfused with interstitial fluid. Three types of human breast cancer cell lines (MCF-7, MDA-MB-231, and SUM-159PT) were cultured on this T-MOC platform, and their drug response and resistance to doxorubicin were characterized by time-lapse quantitative fluorescence microscopy. To study the effects of nanoparticle-mediated drug delivery, the transport and action of doxorubicin encapsulated nanoparticles were also examined. Based on the experimental data obtained, a theoretical model was developed to quantify and ultimately predict the cellular transport processes of drugs cell-type specifically. The results demonstrate that the cellular drug transport can be cell-type-specifically quantified by rate constants representing the uptake and efflux of doxorubicin across the cellular membrane. PMID:27228477

  14. Pigmented lichenoid drug eruption secondary to chloroquine therapy: an unusual presentation in lower lip.

    PubMed

    Moraes, P C; Noce, C W; Thomaz, L A; Cintra, M L; Correa, M E P

    2011-06-01

    Antimalarial drugs, like chloroquine, may produce hyperpigmentation of the oral mucosa, affecting most commonly the palate. Its pathogenesis is not clear; an increased production of melanin is currently believed to be the cause of this oral manifestation. The purpose of this study was to report a case of atypical oral mucosal hyperpigmentation secondary to antimalarial therapy. A 66-year-old, dark skinned woman was evaluated for oral pigmentation. The patient had a history of chloroquine therapy, and presented a diffuse blue-gray pigmentation in the hard palate and, mainly, in the lower lip. Diagnostic hypothesis were of physiologic pigmentation, drug-induced pigmentation, pigmentation associated with systemic diseases, smoker's melanosis and post-inflammatory pigmentation. Incisional biopsy was conducted and histopathological examination revealed lichenoid dermatitis and pigment incontinence. Fontana-Masson staining was positive for melanin, but Perl's iron staining was negative. The histopathological diagnosis was consistent with melanin incontinence related to drug-induced lichenoid reaction secondary to chloroquine therapy. Adequate correlation of clinical and microscopic aspects was essential for the definitive diagnosis, especially in atypical cases. This diagnosis is of great relevance for the patient, since the oral manifestation might be an early sign of ocular complications due to antimalarial therapy. Therefore, the identification of these oral manifestations indicates regular evaluations by an ophtalmologist, preventing greater complications of antimalarial therapy for the patient. PMID:21666569

  15. Macroautophagy is dispensable for growth of KRAS mutant tumors and chloroquine efficacy.

    PubMed

    Eng, Christina H; Wang, Zuncai; Tkach, Diane; Toral-Barza, Lourdes; Ugwonali, Savuth; Liu, Shanming; Fitzgerald, Stephanie L; George, Elizabeth; Frias, Elizabeth; Cochran, Nadire; De Jesus, Rowena; McAllister, Gregory; Hoffman, Gregory R; Bray, Kevin; Lemon, LuAnna; Lucas, Judy; Fantin, Valeria R; Abraham, Robert T; Murphy, Leon O; Nyfeler, Beat

    2016-01-01

    Macroautophagy is a key stress-response pathway that can suppress or promote tumorigenesis depending on the cellular context. Notably, Kirsten rat sarcoma (KRAS)-driven tumors have been reported to rely on macroautophagy for growth and survival, suggesting a potential therapeutic approach of using autophagy inhibitors based on genetic stratification. In this study, we evaluated whether KRAS mutation status can predict the efficacy to macroautophagy inhibition. By profiling 47 cell lines with pharmacological and genetic loss-of-function tools, we were unable to confirm that KRAS-driven tumor lines require macroautophagy for growth. Deletion of autophagy-related 7 (ATG7) by genome editing completely blocked macroautophagy in several tumor lines with oncogenic mutations in KRAS but did not inhibit cell proliferation in vitro or tumorigenesis in vivo. Furthermore, ATG7 knockout did not sensitize cells to irradiation or to several anticancer agents tested. Interestingly, ATG7-deficient and -proficient cells were equally sensitive to the antiproliferative effect of chloroquine, a lysosomotropic agent often used as a pharmacological tool to evaluate the response to macroautophagy inhibition. Moreover, both cell types manifested synergistic growth inhibition when treated with chloroquine plus the tyrosine kinase inhibitors erlotinib or sunitinib, suggesting that the antiproliferative effects of chloroquine are independent of its suppressive actions on autophagy. PMID:26677873

  16. Macroautophagy is dispensable for growth of KRAS mutant tumors and chloroquine efficacy

    PubMed Central

    Eng, Christina H.; Wang, Zuncai; Tkach, Diane; Toral-Barza, Lourdes; Ugwonali, Savuth; Liu, Shanming; Fitzgerald, Stephanie L.; George, Elizabeth; Frias, Elizabeth; Cochran, Nadire; De Jesus, Rowena; McAllister, Gregory; Hoffman, Gregory R.; Bray, Kevin; Lemon, LuAnna; Lucas, Judy; Fantin, Valeria R.; Abraham, Robert T.; Murphy, Leon O.; Nyfeler, Beat

    2016-01-01

    Macroautophagy is a key stress-response pathway that can suppress or promote tumorigenesis depending on the cellular context. Notably, Kirsten rat sarcoma (KRAS)-driven tumors have been reported to rely on macroautophagy for growth and survival, suggesting a potential therapeutic approach of using autophagy inhibitors based on genetic stratification. In this study, we evaluated whether KRAS mutation status can predict the efficacy to macroautophagy inhibition. By profiling 47 cell lines with pharmacological and genetic loss-of-function tools, we were unable to confirm that KRAS-driven tumor lines require macroautophagy for growth. Deletion of autophagy-related 7 (ATG7) by genome editing completely blocked macroautophagy in several tumor lines with oncogenic mutations in KRAS but did not inhibit cell proliferation in vitro or tumorigenesis in vivo. Furthermore, ATG7 knockout did not sensitize cells to irradiation or to several anticancer agents tested. Interestingly, ATG7-deficient and -proficient cells were equally sensitive to the antiproliferative effect of chloroquine, a lysosomotropic agent often used as a pharmacological tool to evaluate the response to macroautophagy inhibition. Moreover, both cell types manifested synergistic growth inhibition when treated with chloroquine plus the tyrosine kinase inhibitors erlotinib or sunitinib, suggesting that the antiproliferative effects of chloroquine are independent of its suppressive actions on autophagy. PMID:26677873

  17. Increased Systemic Exposure of Methotrexate by a Polyphenol-Rich Herb via Modulation on Efflux Transporters Multidrug Resistance-Associated Protein 2 and Breast Cancer Resistance Protein.

    PubMed

    Yu, Chung-Ping; Hsieh, Yun-Chung; Shia, Chi-Sheng; Hsu, Pei-Wen; Chen, Jen-Yuan; Hou, Yu-Chi; Hsieh, Yo-Wen

    2016-01-01

    Scutellariae radix (SR, roots of Scutellaria baicalensis Georgi), a popular Chinese medicine, contains plenty of flavonoids such as baicalin, wogonoside, baicalein, and wogonin. Methotrexate (MTX), an important immunosuppressant with a narrow therapeutic index, is a substrate of multidrug resistance-associated proteins (MRPs) and breast cancer resistance protein (BCRP). This study investigated the effect of SR on MTX pharmacokinetics and the underlying mechanisms. Rats were orally administered MTX alone and with 1.0 or 2.0 g/kg of SR. The serum concentrations of MTX were determined by a fluorescence polarization immunoassay. Cell models were used to explore the involvement of MRP2 and BCRP in the interaction. The results showed that 1.0 g/kg of SR significantly increased Cmax, AUC(0-30), AUC(0-2880), and mean residence time (MRT) of MTX by 50%, 45%, 501%, and 347%, respectively, and 2.0 g/kg of SR significantly enhanced the AUC(0-2880) and MRT by 242% and 293%, respectively, but decreased AUC(0-30) by 41%. Cell line studies indicated that SR activated the BCRP-mediated efflux transport, whereas the serum metabolites of SR inhibited both the BCRP- and MRP2-mediated efflux transports. In conclusion, SR ingestion increased the systemic exposure and MRT of MTX via modulation on MRP2 and BCRP. PMID:26852865

  18. Augmentation of gastric acid secretion by chloroquine and amodiaquine in the rat stomach.

    PubMed

    Ajeigbe, K O; Emikpe, B O; Olaleye, S B

    2012-06-01

    Gastrointestinal mucosal integrity has been shown to be altered by chloroquine and amodiaquine, although the exact mechanism is not clear. Since Gastric Acid Secretion (GAS) plays significant role in the etiology of ulcer, the present study was aimed at investigating the effect of chloroquine and amodiaquine on GAS, Parietal Cell Mass (PCM) and Gastric Mucous Cell Population (GMP) in rats. Male albino wistar rats were randomly assigned into three groups viz: control, chloroquine (CQ, 3 mg/kg), amodiaquine (AQ, 10 mg/kg). Basal GAS as well as secretion in response to histamine and carbachol was measured by continuous perfusion of the stomach with normal saline (1ml/minute) under urethane anaesthesia (0.6 mg/100 g). After obtaining a steady basal output response to normal saline in all animals, the antimalaria drugs were administered intramuscularly and the peak responses to each drug obtained. Further assessment of the roles of histaminergic and muscarinic receptors were done using ranitidine (H2 antagonist) and atropine (M antagonist) in the treated animals. PCM and GMP were determined in the stomach samples by histometry. The basal acid output was 0.70 ± 0.01 mmol/10 mins. Chloroquine and amodiaquine produced increase in acid output to a peak of 1.35 ±0.03 mmol/10 mins (92.9%) and 1.40 ± 0.03 mmol/10 mins (100%) respectively. Histamine and carbachol elicited 107% and 100% increase acid secretion when compared with the basal output respectively. CQ and AQ potentiated histamine-induced secretory rate which peaked at 1.60 ± 0.02 mmol/10 mins and 1.70 ± 0.03 mmol/10 mins respectively. Similarly, the carbachol-induced acid secretory response was potentiated by CQ and AQ to a peak of 1.45 ± 0.02 mmol/10 mins and 1.50 ± 0.03 mmol/10 mins. Ranitidine and atropine attenuated histamine and carbachol induced acid secretion, but did not abolish it. CQ and AQ increased significantly the parietal cell numbers in the gastric mucosa (21±0.7 and 24±0.7 versus 15.2±0

  19. Role of a putative amino acid transporter in fungal disease resistance in alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accessions of the model legume Medicago truncatula, a close relative of alfalfa, were identified that are resistant to several foliar pathogens, and microarray technology was used to identify genes specifically expressed in the resistance response. A large proportion of the up-regulated genes had on...

  20. Analysis of rice PDR-like ABC transporter genes in sheath blight resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight caused by Rhizoctonia solani is one of the most damaging diseases of rice worldwide. To understand the molecular mechanism of resistance, we identified 450 differentially expressed genes in a resistant rice cultivar Jasmine 85 after R. solani infection with a combination of DNA microar...

  1. Inhibition by chloroquine of the class II major histocompatibility complex-restricted presentation of endogenous antigens varies according to the cellular origin of the antigen-presenting cells, the nature of the T-cell epitope, and the responding T cell.

    PubMed Central

    Lombard-Platlet, S; Bertolino, P; Deng, H; Gerlier, D; Rabourdin-Combe, C

    1993-01-01

    Chloroquine treatment of antigen-presenting cells (APC) was explored as a tool to investigate the processing pathway for major histocompatibility complex (MHC) class II-restricted presentation of the endogenous secreted hen egg lysozyme (HEL) and transmembrane measles virus haemagglutinin (HA). A 72-hr pretreatment of the APC with 25 microM chloroquine blocked the presentation of the HEL(52-61) T-cell epitope generated from endogenous HEL to the I-Ak-restricted 3A9 T-cell hybridoma by MHC class II-transfected L cells expressing the invariant chain (Ii). The presentation of exogenously added HEL peptides was not affected. Under the same conditions, no inhibition of the presentation of HEL(106-116) to the I-Ed-restricted G28 high-avidity T-cell hybridoma, nor of HA when synthesized by L cells, was observed. When B-lymphoid APC were used, inhibition was observed in every case with a low number of B APC pretreated for 48 hr with chloroquine prior to the T-cell stimulation test. Moreover, addition of chloroquine to untreated B APC during the T-cell stimulation assay was sufficient to inhibit completely the presentation of HEL(106-116) to the B10.D24.42 low avidity T-cell hybridoma. Altogether these studies suggest that an apparent resistance of endogenous Ag presentation to chloroquine inhibition may not necessarily indicate the existence of a non-endosomal pathway but may be due to the nature of the T-cell epitope, to the use of 'non-professional' APC such as L cells, to the use of T cells of high avidity, and to high amounts of pre-existing MHC class II-peptide complexes expressed by the APC. We demonstrate here that, at least in conventional APC such as B cells, class II-restricted presentation of both endogenous secreted HEL and transmembrane HA involves an endosomal pathway. PMID:7508420

  2. Assessment of Markers of Antimalarial Drug Resistance in Plasmodium falciparum Isolates from Pregnant Women in Lagos, Nigeria

    PubMed Central

    Agomo, Chimere Obiora; Oyibo, Wellington Aghoghovwia; Sutherland, Colin; Hallet, Rachael; Oguike, Mary

    2016-01-01

    Background The use of antimalarial drugs for prevention and treatment is a major strategy in the prevention of malaria in pregnancy. Although sulphadoxine-pyrimethamine (SP) is currently recommended for intermittent preventive treatment of malaria during pregnancy in Nigeria, previously used drugs for prophylaxis such as chloroquine (CQ) and pyrimethamine are accessible as they are purchased over the counter. This study describes the markers of absence or presence of resistance to quinoline (Pfcrt and Pfmdr 1) and type 1 antifolate antimalarial medicines (Pfdhfr). Methods Plasmodium falciparum-positive dried blood spots from pregnant women attending antenatal clinics for the first time during current pregnancy were investigated for the presence of mutations at codons 72–76 of Plasmodium falciparum chloroquine resistance transporter (Pfcrt) gene by real time polymerase chain reaction (PCR) using haplotype-specific probes. PCR followed by sequence analysis was used to identify mutations at codons 86, 184, 1034, 1042 and 1246 of P. falciparum multi-drug resistance-1 (Pfmdr1) gene; and codons 16, 50, 51, 59, 108, 140 and 164 of Pfdhfr gene. Results Two haplotypes of Pfcrt (n = 54) were observed: CVMNK 13(24.2%) and CVIET 41 (75.9%) of the samples. The SVMNT haplotype was absent in this population. The Pfmdr1 (n = 28) haplotypes were NYSND 15(53.6%), YYSND 5(17.9%), NFSND 6(21.4%) and YFSND 2(7.1%). The Pfdhfr (n = 15) were ACNCSVI 4(26.7%), and ACICNSVI 1(6.7%) and ACIRNVI 10 (66.7%). The rate of occurrence of Pfcrt 76T, Pfdhfr108N, Pfmdr186Yand184F were 75.9%, 73.3%, 25% and 28.1% respectively. The Pfmdr1 86Y was associated with low parasitaemia (median = 71 parasites/μl, P = 0.024) while Pfcrt 76T was associated with young maternal age (mean 24.1 ± 4.5 years; P = 0.006). The median parasitaemia were similar (P>0.05) in wild and mutant strains of Pfcrt 76, Pfmdr1 184 and Pfdhfr 108. There was no association between gravidity or gestational age of the women and

  3. Intrinsic SiOx-based unipolar resistive switching memory. II. Thermal effects on charge transport and characterization of multilevel programing

    NASA Astrophysics Data System (ADS)

    Chang, Yao-Feng; Fowler, Burt; Chen, Ying-Chen; Chen, Yen-Ting; Wang, Yanzhen; Xue, Fei; Zhou, Fei; Lee, Jack C.

    2014-07-01

    Multilevel programing and charge transport characteristics of intrinsic SiOx-based resistive switching memory are investigated using TaN/SiOx/n++Si (MIS) and TiW/SiOx/TiW (MIM) device structures. Current transport characteristics of high- and low-resistance states (HRS and LRS) are studied in both device structures during multilevel operation. Analysis of device thermal response demonstrates that the effective electron energy barrier is strongly dependent on the resistance of the programed state, with estimates of 0.1 eV in the LRS and 0.6 eV in the HRS. Linear data fitting and conductance analyses indicate Poole-Frenkel emission or hopping conductance in the low-voltage region, whereas Fowler-Nordheim (F-N) or trap-assisted tunneling (TAT) is indicated at moderate voltage. Characterizations using hopping transport lead to hopping distance estimates of ˜1 nm in the LRS for both device structures. Relative permittivity values (ɛr) were extracted using the Poole-Frenkel formulism and estimates of local filament temperature, where ɛr values were ˜80 in the LRS and ˜4 in the HRS, suggesting a strongly polarized medium in the LRS. The onset of F-N tunneling or TAT corresponds to an observed "overshoot" in the I-V response with an estimated threshold of 1.6 ± 0.2 V, in good agreement with reported electro-luminescence results for LRS devices. Resistive switching is discussed in terms of electrochemical reactions between common SiO2 defects, and specific defect energy levels are assigned to the dominant transitions in the I-V response. The overshoot response in the LRS is consistent with TAT through either the Eγ' oxygen vacancy or the hydrogen bridge defect, both of which are reported to have an effective bandgap of 1.7 eV. The SET threshold at ˜2.5 V is modeled as hydrogen release from the (Si-H)2 defect to generate the hydrogen bridge, and the RESET transition is modeled as an electrochemical reaction that re-forms (SiH)2. The results provide further insights

  4. The modulation of ABC transporter-mediated multidrug resistance in cancer: a review of the past decade.

    PubMed

    Kathawala, Rishil J; Gupta, Pranav; Ashby, Charles R; Chen, Zhe-Sheng

    2015-01-01

    ATP-binding cassette (ABC) transporters represent one of the largest and oldest families of membrane proteins in all extant phyla from prokaryotes to humans, which couple the energy derived from ATP hydrolysis essentially to translocate, among various substrates, toxic compounds across the membrane. The fundamental functions of these multiple transporter proteins include: (1) conserved mechanisms related to nutrition and pathogenesis in bacteria, (2) spore formation in fungi, and (3) signal transduction, protein secretion and antigen presentation in eukaryotes. Moreover, one of the major causes of multidrug resistance (MDR) and chemotherapeutic failure in cancer therapy is believed to be the ABC transporter-mediated active efflux of a multitude of structurally and mechanistically distinct cytotoxic compounds across membranes. It has been postulated that ABC transporter inhibitors known as chemosensitizers may be used in combination with standard chemotherapeutic agents to enhance their therapeutic efficacy. The current paper reviews the advance in the past decade in this important domain of cancer chemoresistance and summarizes the development of new compounds and the re-evaluation of compounds originally designed for other targets as transport inhibitors of ATP-dependent drug efflux pumps. PMID:25554624

  5. The non-ABC drug transporter RLIP76 (RALBP-1) plays a major role in the mechanisms of drug resistance.

    PubMed

    Awasthi, Yogesh C; Sharma, Rajendra; Yadav, Sushma; Dwivedi, Seema; Sharma, Abha; Awasthi, Sanjay

    2007-05-01

    RLIP76 or Ral binding protein (RalBP-1) was initially cloned as a Ral-effector that was proposed as a link between Ral and Ras pathways. This protein is encoded in humans on chromosome 18p11.3 by a gene with 11 exons and 9 introns and is found ubiquitously from drosophila to humans. RLIP76 displays inhibitory GTPase activity toward Rho/Rac class G-protein cdc42 which is involved in regulation of cytoskeletal organization, lamellipodia, cell migration and apoptosis via Ras. We have recently shown that RLIP76 is also a multispecific transporter of chemotherapeutic agents and glutathione conjugates (GS-E). In human cells RLIP76 accounts for more than two third of the transport activity for GS-E and drugs as opposed to the ABC-transporters including MRP1, which account for less than one third of this activity. Evidence is mounting that RLIP76 is a stress-responsive multi-specific, non-ABC transporter which represents an entirely novel link between stress-inducible G-protein signaling, receptor tyrosine-kinase signaling, endocytosis, heat-shock and stress defense pathways, and transport mediated drug-resistance. The expression of RLIP76 is significantly greater in human cancer cells of diverse origin as compared to the non-malignant cells. Inhibition of RLIP76, using antibodies towards a cell surface epitope, or depletion of RLIP76 using either siRNA or anti-sense phosphorothioate oligonucleotides preferentially causes apoptosis in malignant cells. Administration of RLIP76 antibodies, siRNA, or anti-sense oligonucleotides to mice bearing syngeneic B16 mouse melanoma tumors causes rapid and complete regression of tumors. Studies summarized in this review strongly suggest that RLIP76 is a logical target for clinical intervention of not only multi-drug resistance but also for diseases resulting from oxidative stress. PMID:17504221

  6. Functional Characterization of AbeD, an RND-Type Membrane Transporter in Antimicrobial Resistance in Acinetobacter baumannii

    PubMed Central

    Srinivasan, Vijaya Bharathi; Venkataramaiah, Manjunath; Mondal, Amitabha; Rajamohan, Govindan

    2015-01-01

    Background Acinetobacter baumannii is becoming an increasing menace in health care settings especially in the intensive care units due to its ability to withstand adverse environmental conditions and exhibit innate resistance to different classes of antibiotics. Here we describe the biological contributions of abeD, a novel membrane transporter in bacterial stress response and antimicrobial resistance in A. baumannii. Results The abeD mutant displayed ~ 3.37 fold decreased survival and >5-fold reduced growth in hostile osmotic (0.25 M; NaCl) and oxidative (2.631 μM–6.574 μM; H2O2) stress conditions respectively. The abeD inactivated cells displayed increased susceptibility to ceftriaxone, gentamicin, rifampicin and tobramycin (~ 4.0 fold). The mutant displayed increased sensitivity to the hospital-based disinfectant benzalkonium chloride (~3.18-fold). In Caenorhabditis elegans model, the abeD mutant exhibited (P<0.01) lower virulence capability. Binding of SoxR on the regulatory fragments of abeD provide strong evidence for the involvement of SoxR system in regulating the expression of abeD in A. baumannii. Conclusion This study demonstrates the contributions of membrane transporter AbeD in bacterial physiology, stress response and antimicrobial resistance in A. baumannii for the first time. PMID:26496475

  7. HG-829 is a potent noncompetitive inhibitor of the ATP-binding cassette multidrug resistance transporter ABCB1.

    PubMed

    Caceres, Gisela; Robey, Robert W; Sokol, Lubomir; McGraw, Kathy L; Clark, Justine; Lawrence, Nicholas J; Sebti, Said M; Wiese, Michael; List, Alan F

    2012-08-15

    Transmembrane drug export mediated by the ATP-binding cassette (ABC) transporter P-glycoprotein contributes to clinical resistance to antineoplastics. In this study, we identified the substituted quinoline HG-829 as a novel, noncompetitive, and potent P-glycoprotein inhibitor that overcomes in vitro and in vivo drug resistance. We found that nontoxic concentrations of HG-829 restored sensitivity to P-glycoprotein oncolytic substrates. In ABCB1-overexpressing cell lines, HG-829 significantly enhanced cytotoxicity to daunorubicin, paclitaxel, vinblastine, vincristine, and etoposide. Coadministration of HG-829 fully restored in vivo antitumor activity of daunorubicin in mice without added toxicity. Functional assays showed that HG-829 is not a Pgp substrate or competitive inhibitor of Pgp-mediated drug efflux but rather acts as a noncompetitive modulator of P-glycoprotein transport function. Taken together, our findings indicate that HG-829 is a potent, long-acting, and noncompetitive modulator of P-glycoprotein export function that may offer therapeutic promise for multidrug-resistant malignancies. PMID:22761337

  8. The ABC transporter YejABEF is required for resistance to antimicrobial peptides and the virulence of Brucella melitensis

    PubMed Central

    Wang, Zhen; Bie, Pengfei; Cheng, Jie; Lu, Lin; Cui, Buyun; Wu, Qingmin

    2016-01-01

    The ability to resist the killing effects of host antimicrobial peptides (AMPs) plays a vital role in the virulence of pathogens. The Brucella melitensis NI genome has a gene cluster that encodes ABC transport. In this study, we constructed yejA1, yejA2, yejB, yejE, yejF, and whole yej operon deletion mutants, none of which exhibited discernible growth defect in TSB or minimal medium. Unlike their parental strain, the mutants showed a significantly increased sensitivity to acidic stress. The NIΔyejE and NIΔyejABEF mutants were also more sensitive than B. melitensis NI to polymyxin B, and the expression of yej operon genes was induced by polymyxin B. Moreover, cell and mouse infection assays indicated that NIΔyejE and NIΔyejABEF have restricted invasion and replication abilities inside macrophages and are rapidly cleared from the spleens of infected mice. These findings indicate that the ABC transporter YejABEF is required for the virulence of Brucella, suggesting that resistance to host antimicrobials is a key mechanism for Brucella to persistently survive in vivo. This study provided insights that led us to further investigate the potential correlation of AMP resistance with the mechanisms of immune escape and persistent infection by pathogens. PMID:27550726

  9. The ABC transporter YejABEF is required for resistance to antimicrobial peptides and the virulence of Brucella melitensis.

    PubMed

    Wang, Zhen; Bie, Pengfei; Cheng, Jie; Lu, Lin; Cui, Buyun; Wu, Qingmin

    2016-01-01

    The ability to resist the killing effects of host antimicrobial peptides (AMPs) plays a vital role in the virulence of pathogens. The Brucella melitensis NI genome has a gene cluster that encodes ABC transport. In this study, we constructed yejA1, yejA2, yejB, yejE, yejF, and whole yej operon deletion mutants, none of which exhibited discernible growth defect in TSB or minimal medium. Unlike their parental strain, the mutants showed a significantly increased sensitivity to acidic stress. The NIΔyejE and NIΔyejABEF mutants were also more sensitive than B. melitensis NI to polymyxin B, and the expression of yej operon genes was induced by polymyxin B. Moreover, cell and mouse infection assays indicated that NIΔyejE and NIΔyejABEF have restricted invasion and replication abilities inside macrophages and are rapidly cleared from the spleens of infected mice. These findings indicate that the ABC transporter YejABEF is required for the virulence of Brucella, suggesting that resistance to host antimicrobials is a key mechanism for Brucella to persistently survive in vivo. This study provided insights that led us to further investigate the potential correlation of AMP resistance with the mechanisms of immune escape and persistent infection by pathogens. PMID:27550726

  10. Inhibition of multixenobiotic resistance transporters (MXR) by silver nanoparticles and ions in vitro and in Daphnia magna.

    PubMed

    Georgantzopoulou, Anastasia; Cambier, Sébastien; Serchi, Tommaso; Kruszewski, Marcin; Balachandran, Yekkuni L; Grysan, Patrick; Audinot, Jean-Nicolas; Ziebel, Johanna; Guignard, Cédric; Gutleb, Arno C; Murk, AlberTinka J

    2016-11-01

    The P-glycoprotein (P-gp, ABCB1) and multidrug resistance associated protein 1 (MRP1), important members of the ABC (ATP-binding cassette) transporters, protect cells and organisms via efflux of xenobiotics and are responsible for the phenomenon of multidrug or multixenobiotic resistance (MXR). In this study we first evaluated, in vitro, the interaction of silver nanoparticles (Ag NPs, 20, 23 and 27nm), Ag 200nm particles and Ag ions (AgNO3) with MXR efflux transporters using MDCKII and the P-gp over-expressing MDCKII-MDR1 cells and calcein-AM as a substrate of the transporters. Next the in vivo modulation of MXR activity was studied in Daphnia magna juveniles with the model P-gp and MRP1 inhibitors verapamil-HCl and MK571, respectively. The common environmental contaminants perfluorooctane sulfonate and bisphenol A, previously observed to interfere with the P-gp in vitro, also inhibited the efflux of calcein in vivo. Small-sized Ag NPs (with biomolecules present on the surface) and AgNO3 inhibited the MXR activity in daphnids and MDCKII-MDR1 cells, but abcb1 gene expression remained unchanged. Both Ag NPs and dissolved ions contributed to the effects. This study provides evidence of the interference of Ag NPs and AgNO3 with the MXR activity both in vitro and in D. magna, and should be taken into account when Ag NP toxicity is assessed. PMID:27376922

  11. Prediction of multi-drug resistance transporters using a novel sequence analysis method [version 2; referees: 2 approved

    DOE PAGESBeta

    McDermott, Jason E.; Bruillard, Paul; Overall, Christopher C.; Gosink, Luke; Lindemann, Stephen R.

    2015-03-09

    There are many examples of groups of proteins that have similar function, but the determinants of functional specificity may be hidden by lack of sequencesimilarity, or by large groups of similar sequences with different functions. Transporters are one such protein group in that the general function, transport, can be easily inferred from the sequence, but the substrate specificity can be impossible to predict from sequence with current methods. In this paper we describe a linguistic-based approach to identify functional patterns from groups of unaligned protein sequences and its application to predict multi-drug resistance transporters (MDRs) from bacteria. We first showmore » that our method can recreate known patterns from PROSITE for several motifs from unaligned sequences. We then show that the method, MDRpred, can predict MDRs with greater accuracy and positive predictive value than a collection of currently available family-based models from the Pfam database. Finally, we apply MDRpred to a large collection of protein sequences from an environmental microbiome study to make novel predictions about drug resistance in a potential environmental reservoir.« less

  12. Prediction of multi-drug resistance transporters using a novel sequence analysis method [version 2; referees: 2 approved

    SciTech Connect

    McDermott, Jason E.; Bruillard, Paul; Overall, Christopher C.; Gosink, Luke; Lindemann, Stephen R.

    2015-03-09

    There are many examples of groups of proteins that have similar function, but the determinants of functional specificity may be hidden by lack of sequencesimilarity, or by large groups of similar sequences with different functions. Transporters are one such protein group in that the general function, transport, can be easily inferred from the sequence, but the substrate specificity can be impossible to predict from sequence with current methods. In this paper we describe a linguistic-based approach to identify functional patterns from groups of unaligned protein sequences and its application to predict multi-drug resistance transporters (MDRs) from bacteria. We first show that our method can recreate known patterns from PROSITE for several motifs from unaligned sequences. We then show that the method, MDRpred, can predict MDRs with greater accuracy and positive predictive value than a collection of currently available family-based models from the Pfam database. Finally, we apply MDRpred to a large collection of protein sequences from an environmental microbiome study to make novel predictions about drug resistance in a potential environmental reservoir.

  13. Algorithm for resistance to flow and transport in sand-bed channels

    USGS Publications Warehouse

    Bennett, J.P.

    1995-01-01

    An algorithm is developed that relates depth to discharge and determines bed- and suspended-load transport for the entire range of bed forms found in sand-bed channels; equilibrium-state geometry of lower flow regime bedforms is also predicted. A Meyer-Peter-type formulation is used to compute sand transport in the bed-load layer and for computing suspended sand transport, McLean's procedure is adopted. A bed-form classifcation scheme is developed. The algorithm produces overall geometric averages of predicted to observed depth and predicted to observed transport of 1.00. For a verification data set of 855 observations, mostly from rivers and canals, the overall geometric averages of predicted to observed depth and transport are 0.87 and 1.14. -from Author

  14. Development, Maintenance, and Reversal of Multiple Drug Resistance: At the Crossroads of TFPI1, ABC Transporters, and HIF1α

    PubMed Central

    Arnason, Terra; Harkness, Troy

    2015-01-01

    Early detection and improved therapies for many cancers are enhancing survival rates. Although many cytotoxic therapies are approved for aggressive or metastatic cancer; response rates are low and acquisition of de novo resistance is virtually universal. For decades; chemotherapeutic treatments for cancer have included anthracyclines such as Doxorubicin (DOX); and its use in aggressive tumors appears to remain a viable option; but drug resistance arises against DOX; as for all other classes of compounds. Our recent work suggests the anticoagulant protein Tissue Factor Pathway Inhibitor 1α (TFPI1α) plays a role in driving the development of multiple drug resistance (MDR); but not maintenance; of the MDR state. Other factors; such as the ABC transporter drug efflux pumps MDR-1/P-gp (ABCB1) and BCRP (ABCG2); are required for MDR maintenance; as well as development. The patient population struggling with therapeutic resistance specifically requires novel treatment options to resensitize these tumor cells to therapy. In this review we discuss the development, maintenance, and reversal of MDR as three distinct phases of cancer biology. Possible means to exploit these stages to reverse MDR will be explored. Early molecular detection of MDR cancers before clinical failure has the potential to offer new approaches to fighting MDR cancer. PMID:26501324

  15. Sensitive radioimmunoassay and enzyme-linked immunosorbent assay for the simultaneous determination of chloroquine and its metabolites in biological fluids

    SciTech Connect

    Escande, C.; Chevalier, P.; Verdier, F.; Bourdon, R. )

    1990-01-01

    Two new methods for the simultaneous determination of chloroquine and its two main metabolites (monodesethylchloroquine and bisdesethylchloroquine) in biological samples, radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA), are described. Antiserum is produced in rabbits immunized with N-(2-carboxyethyl)desethylchloroquine:protein conjugate. Besides chloroquine, this antiserum recognizes with good affinity the two main metabolites, monodesethylchloroquine and bisdesethylchloroquine (70 and 40% of crossreaction, respectively). Amodiaquine cross reacts by 4.5%; cross reactions with monodesethylamodiaquine, bisdesethylamodiaquine, and other antimalarial drugs are less than 1%. No extraction step or sample preparation is required for either system. Sensitivity limits are, respectively, 0.70 nM (3 pg of chloroquine sulfate measured in 10 microL of plasma sample) for RIA, and 10 nM (22 pg of chloroquine sulfate measured in 5 microL of plasma sample) for ELISA. The interassay coefficients of variation are, respectively, less than 10 and less than 16% for RIA and ELISA in the range 14-410 nM (6-180 ng/mL). The results of both methods are well correlated (r = 0.97) and correlate with spectrophotometry (r = 0.98) and HPLC results (r = 0.93). Because of their high sensitivity, both methods can be used in the case of chloroquine poisoning and in the control of malaria prophylaxis and treatment.

  16. A Randomized Comparison of Chloroquine Versus Dihydroartemisinin-Piperaquine for the Treatment of Plasmodium vivax Infection in Vietnam.

    PubMed

    Thuan, Phung Duc; Ca, Nguyen Thuy Nha; Van Toi, Pham; Nhien, Nguyen Thanh Thuy; Thanh, Ngo Viet; Anh, Nguyen Duc; Phu, Nguyen Hoan; Thai, Cao Quang; Thai, Le Hong; Hoa, Nhu Thi; Dong, Le Thanh; Loi, Mai Anh; Son, Do Hung; Khanh, Tran Tinh Ngoc; Dolecek, Christiane; Nhan, Ho Thi; Wolbers, Marcel; Thwaites, Guy; Farrar, Jeremy; White, Nicholas J; Hien, Tran Tinh

    2016-04-01

    A total of 128 Vietnamese patients with symptomatic Plasmodium vivax mono-infections were enrolled in a prospective, open-label, randomized trial to receive either chloroquine or dihydroartemisinin-piperaquine (DHA-PPQ). The proportions of patients with adequate clinical and parasitological responses were 47% in the chloroquine arm (31 of 65 patients) and 66% in the DHA-PPQ arm (42 of 63 patients) in the Kaplan-Meier intention-to-treat analysis (absolute difference 19%, 95% confidence interval = 0-37%), thus establishing non-inferiority of DHA-PPQ. Fever clearance time (median 24 versus 12 hours,P= 0.02), parasite clearance time (median 36 versus 18 hours,P< 0.001), and parasite clearance half-life (mean 3.98 versus 1.80 hours,P< 0.001) were all significantly shorter in the DHA-PPQ arm. All cases of recurrent parasitemia in the chloroquine arm occurred from day 33 onward, with corresponding whole blood chloroquine concentration lower than 100 ng/mL in all patients. Chloroquine thus remains efficacious for the treatment of P. vivax malaria in southern Vietnam, but DHA-PPQ provides more rapid symptomatic and parasitological recovery. PMID:26856909

  17. A Randomized Comparison of Chloroquine versus Dihydroartemisinin–Piperaquine for the Treatment of Plasmodium vivax Infection in Vietnam

    PubMed Central

    Thuan, Phung Duc; Ca, Nguyen Thuy Nha; Van Toi, Pham; Nhien, Nguyen Thanh Thuy; Thanh, Ngo Viet; Anh, Nguyen Duc; Phu, Nguyen Hoan; Thai, Cao Quang; Hong Thai, Le; Hoa, Nhu Thi; Thanh Dong, Le; Loi, Mai Anh; Son, Do Hung; Khanh, Tran Tinh Ngoc; Dolecek, Christiane; Nhan, Ho Thi; Wolbers, Marcel; Thwaites, Guy; Farrar, Jeremy; White, Nicholas J.; Hien, Tran Tinh

    2016-01-01

    A total of 128 Vietnamese patients with symptomatic Plasmodium vivax mono-infections were enrolled in a prospective, open-label, randomized trial to receive either chloroquine or dihydroartemisinin–piperaquine (DHA-PPQ). The proportions of patients with adequate clinical and parasitological responses were 47% in the chloroquine arm (31 of 65 patients) and 66% in the DHA-PPQ arm (42 of 63 patients) in the Kaplan–Meier intention-to-treat analysis (absolute difference 19%, 95% confidence interval = 0–37%), thus establishing non-inferiority of DHA-PPQ. Fever clearance time (median 24 versus 12 hours, P = 0.02), parasite clearance time (median 36 versus 18 hours, P < 0.001), and parasite clearance half-life (mean 3.98 versus 1.80 hours, P < 0.001) were all significantly shorter in the DHA-PPQ arm. All cases of recurrent parasitemia in the chloroquine arm occurred from day 33 onward, with corresponding whole blood chloroquine concentration lower than 100 ng/mL in all patients. Chloroquine thus remains efficacious for the treatment of P. vivax malaria in southern Vietnam, but DHA-PPQ provides more rapid symptomatic and parasitological recovery. PMID:26856909

  18. Attenuation of endoplasmic reticulum stress in Pelizaeus-Merzbacher disease by an anti-malaria drug, chloroquine.

    PubMed

    Morimura, Toshifumi; Numata, Yurika; Nakamura, Shoko; Hirano, Eriko; Gotoh, Leo; Goto, Yu-ich; Urushitani, Makoto; Inoue, Ken

    2014-04-01

    Pelizaeus-Merzbacher disease (PMD) is a hypomyelinating disorder caused by the duplication and missense mutations of the proteolipid protein 1 (PLP1) gene. PLP1 missense proteins accumulate in the endoplasmic reticulum (ER) of premature oligodendrocytes and induce severe ER stress followed by apoptosis of the cells. Here, we demonstrate that an anti-malaria drug, chloroquine, decreases the amount of an ER-resident mutant PLP1 containing an alanine-243 to valine (A243V) substitution, which induces severe PMD in human. By preventing mutant PLP1 translation through enhancing the phosphorylation of eukaryotic initiation factor 2 alpha, chloroquine ameliorated the ER stress induced by the mutant protein in HeLa cells. Chroloquine also attenuated ER stress in the primary oligodendrocytes obtained from myelin synthesis deficit (msd) mice, which carry the same PLP1 mutation. In the spinal cords of msd mice, chloroquine inhibited ER stress and upregulated the expression of marker genes of mature oligodendrocytes. Chloroquine-mediated attenuation of ER stress was observed in HeLa cells treated with tunicamycin, an N-glycosylation inhibitor, but not with thapsigargin, a sarco/ER Ca(2+)ATPase inhibitor, which confirms its efficacy against ER stress caused by nascent proteins. These findings indicate that chloroquine is an ER stress attenuator with potential use in treating PMD and possibly other ER stress-related diseases. PMID:24521562

  19. 2D Electrical Resistivity Tomography surveys optimisation of the solutes transports in porous media.

    NASA Astrophysics Data System (ADS)

    Lekmine, G.; Pessel, M.; Auradou, H.

    2009-04-01

    Electrical resistivity tomography applied in borehole or cross-borehole is a method often used to follow the invasion process of pollutant [Daily, 1991]. The aim of this work is to test experimentally the electrode arrays and inversion process used to obtain a spatial representation of tracer propagation in porous media. Experiments were conducted in a plexiglas container with glass beads of 166 microns in diameter. The height of the container is 275 mm, its width 85 mm and its thickness 10 mm. 21 electrodes, equally spaced, are placed along each of the lateral sides of the porous medium : these electrodes are used to perform the electrical measurements. The porous medium is lightened from behind and a video camera records the propagation of the fluids. The fluid containing the tracer (i.e the pollutant) is a water solution containing a small amount of dye together with NaCl (0.5g/l up to 2.0g/l). The medium is first saturated by a water solution containing a slight concentration of NaCl so that its density is smaller than the injected fluid. An upward flow is first established, then the denser fluid is injected at the bottom and over the full width of the medium. In this way, the flow is stabilized by gravity avoiding the development of unstable fingers. Still, the fluids are miscible and a mixing front develops during the flow: in the present study, both the determination by optical and electrical imaging of the mean position of the front and its width are of interest. The comparison of the two techniques allows to study the ability of the inversion process to quantify the solute transport. The electrical measurements are acquired by a standard multi electrode system (IRIS Instruments) and the data are inverted with the Res2Dinv software which models the 2D distribution of conductivity contrasts. The obtained bulk conductivity can be related through Archie's law to fluid conductivity by the porosity and the cementation factor which have been experimentally

  20. Phosphorylation at S384 regulates the activity of the TaALMT1 malate transporter that underlies aluminum resistance in wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study we examined the role of protein phosphorylation & dephosphorylation in the transport properties of the wheat root malate efflux transporter underlying Al resistance, TaALMT1. Preincubation of Xenopus laevis oocytes expressing TaALMT1 with protein kinase inhibitors (K252a and staurospo...

  1. Numerical investigation of interfacial mass transport resistance and two-phase flow in PEM fuel cell air channels

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa

    Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electrochemical engines. The performance of a PEMFC is adversely affected by oxygen (O2) concentration loss from the air flow channel to the cathode catalyst layer (CL). Oxygen transport resistance at the gas diffusion layer (GDL) and air channel interface is a non-negligible component of the O2 concentration loss. Simplified PEMFC performance models in the available literature incorporate the O2 resistance at the GDL-channel interface as an input parameter. However, this parameter has been taken as a constant so far in the available literature and does not reflect variable PEMFC operating conditions and the effect of two-phase flow in the channels. This study numerically calculates the O2 transport resistance at the GDL-air channel interface and expresses this resistance through the non-dimensional Sherwood number (Sh). Local Sh is investigated in an air channel with multiple droplets and films inside. These water features are represented as solid obstructions and only air flow is simulated. Local variations of Sh in the flow direction are obtained as a function of superficial air velocity, water feature size, and uniform spacing between water features. These variations are expressed with mathematical expressions for the PEMFC performance models to utilize and save computational resources. The resulting mathematical correlations for Sh can be utilized in PEMFC performance models. These models can predict cell performance more accurately with the help of the results of this work. Moreover, PEMFC performance models do not need to use a look-up table since the results were expressed through correlations. Performance models can be kept simplified although their predictions will become more realistic. Since two-phase flow in channels is experienced mostly at lower temperatures, performance optimization at low temperatures can be done easier.

  2. Osimertinib (AZD9291) Attenuates the Function of Multidrug Resistance-Linked ATP-Binding Cassette Transporter ABCB1 in Vitro.

    PubMed

    Hsiao, Sung-Han; Lu, Yu-Jen; Li, Yan-Qing; Huang, Yang-Hui; Hsieh, Chia-Hung; Wu, Chung-Pu

    2016-06-01

    The effectiveness of cancer chemotherapy is often circumvented by multidrug resistance (MDR) caused by the overexpression of ATP-binding cassette (ABC) drug transporter ABCB1 (MDR1, P-glycoprotein). Several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been shown previously capable of modulating the function of ABCB1 and reversing ABCB1-mediated MDR in human cancer cells. Furthermore, some TKIs are transported by ABCB1, which results in low oral bioavailability, reduced distribution, and the development of acquired resistance to these TKIs. In this study, we investigated the interaction between ABCB1 and osimertinib, a novel selective, irreversible third-generation EGFR TKI that has recently been approved by the U.S. Food and Drug Administration. We also evaluated the potential impact of ABCB1 on the efficacy of osimertinib in cancer cells, which can present a therapeutic challenge to clinicians in the future. We revealed that although osimertinib stimulates the ATPase activity of ABCB1, overexpression of ABCB1 does not confer resistance to osimertinib. Our results suggest that it is unlikely that the overexpression of ABCB1 can be a major contributor to the development of osimertinib resistance in cancer patients. More significantly, we revealed an additional action of osimertinib that directly inhibits the function of ABCB1 without affecting the expression level of ABCB1, enhances drug-induced apoptosis, and reverses the MDR phenotype in ABCB1-overexpressing cancer cells. Considering that osimertinib is a clinically approved third-generation EGFR TKI, our findings suggest that a combination therapy with osimertinib and conventional anticancer drugs may be beneficial to patients with MDR tumors. PMID:27169328

  3. BC4707 Is a Major Facilitator Superfamily Multidrug Resistance Transport Protein from Bacillus cereus Implicated in Fluoroquinolone Tolerance

    PubMed Central

    Simm, Roger; Vörös, Aniko; Ekman, Jaakko V.; Sødring, Marianne; Nes, Ingerid; Kroeger, Jasmin K.; Saidijam, Massoud; Bettaney, Kim E.; Henderson, Peter J. F.; Salkinoja-Salonen, Mirja; Kolstø, Anne-Brit

    2012-01-01

    Transcriptional profiling highlighted a subset of genes encoding putative multidrug transporters in the pathogen Bacillus cereus that were up-regulated during stress produced by bile salts. One of these multidrug transporters (BC4707) was selected for investigation. Functional characterization of the BC4707 protein in Escherichia coli revealed a role in the energized efflux of xenobiotics. Phenotypic analyses after inactivation of the gene bc4707 in Bacillus cereus ATCC14579 suggested a more specific, but modest role in the efflux of norfloxacin. In addition to this, transcriptional analyses showed that BC4707 is also expressed during growth of B. cereus under non-stressful conditions where it may have a role in the normal physiology of the bacteria. Altogether, the results indicate that bc4707, which is part of the core genome of the B. cereus group of bacteria, encodes a multidrug resistance efflux protein that is likely involved in maintaining intracellular homeostasis during growth of the bacteria. PMID:22615800

  4. The ABC-transporter AtmA is involved in nickel and cobalt resistance of Cupriavidus metallidurans strain CH34.

    PubMed

    Mikolay, André; Nies, Dietrich H

    2009-08-01

    Cupriavidus metallidurans CH34 genome contains an ortholog of Atm1p named AtmA (Rmet_0391, YP_582546). In Saccharomyces cerevisiae, the ABC-type transport system Atm1p is involved in export of iron-sulfur clusters from mitochondria into the cytoplasm for assembly of cytoplasmic iron-sulfur containing proteins. An atmA mutant of C. metallidurans was sensitive to nickel and cobalt but not iron cations. AtmA increased also resistance to these cations in Escherichia coli strains that carry deletions of the genes for other nickel and cobalt transport systems. In C. metallidurans, atmA expression was not significantly induced by nickel and cobalt, but repressed by zinc. AtmA was purified as a 70 kDa protein after expression in E. coli. ATPase activity of AtmA was stimulated by nickel and cobalt. PMID:19132541

  5. The ABC transporter gene family of Caenorhabditis elegans has implications for the evolutionary dynamics of multidrug resistance in eukaryotes

    PubMed Central

    Sheps, Jonathan A; Ralph, Steven; Zhao, Zhongying; Baillie, David L; Ling, Victor

    2004-01-01

    Background Many drugs of natural origin are hydrophobic and can pass through cell membranes. Hydrophobic molecules must be susceptible to active efflux systems if they are to be maintained at lower concentrations in cells than in their environment. Multi-drug resistance (MDR), often mediated by intrinsic membrane proteins that couple energy to drug efflux, provides this function. All eukaryotic genomes encode several gene families capable of encoding MDR functions, among which the ABC transporters are the largest. The number of candidate MDR genes means that study of the drug-resistance properties of an organism cannot be effectively carried out without taking a genomic perspective. Results We have annotated sequences for all 60 ABC transporters from the Caenorhabditis elegans genome, and performed a phylogenetic analysis of these along with the 49 human, 30 yeast, and 57 fly ABC transporters currently available in GenBank. Classification according to a unified nomenclature is presented. Comparison between genomes reveals much gene duplication and loss, and surprisingly little orthology among analogous genes. Proteins capable of conferring MDR are found in several distinct subfamilies and are likely to have arisen independently multiple times. Conclusions ABC transporter evolution fits a pattern expected from a process termed 'dynamic-coherence'. This is an unusual result for such a highly conserved gene family as this one, present in all domains of cellular life. Mechanistically, this may result from the broad substrate specificity of some ABC proteins, which both reduces selection against gene loss, and leads to the facile sorting of functions among paralogs following gene duplication. PMID:15003118

  6. Impaired renal secretion of substrates for the multidrug resistance protein 2 in mutant transport-deficient (TR-) rats.

    PubMed

    Masereeuw, Rosalinde; Notenboom, Sylvia; Smeets, Pascal H E; Wouterse, Alfons C; Russel, Frans G M

    2003-11-01

    Previous studies with mutant transport-deficient rats (TR(-)), in which the multidrug resistance protein 2 (Mrp2) is lacking, have emphasized the importance of this transport protein in the biliary excretion of a wide variety of glutathione conjugates, glucuronides, and other organic anions. Mrp2 is also present in the luminal membrane of proximal tubule cells of the kidney, but little information is available on its role in the renal excretion of xenobiotics. The authors compared renal transport of the fluorescent Mrp2 substrates calcein, fluo-3, and lucifer yellow (LY) between perfused kidneys isolated from Wistar Hannover (WH) and TR(-) rats. Isolated rat kidneys were perfused with 100 nM of the nonfluorescent calcein-AM or 500 nM fluo3-AM, which enter the tubular cells by diffusion and are hydrolyzed intracellularly into the fluorescent anion. The urinary excretion rates of calcein and fluo-3 were 3 to 4 times lower in perfused kidneys from TR(-) rats compared with WH rats. In contrast, the renal excretion of LY (10 micro M, free anion) was somewhat delayed but appeared unimpaired in TR(-) rats. Membrane vesicles from Sf9 cells expressing human MRP2 or human MRP4 indicated that MRP2 exhibits a preferential affinity for calcein and fluo-3, whereas LY is a better substrate for MRP4. We conclude that the renal clearance of the Mrp2 substrates calcein and fluo-3 is significantly reduced in TR(-) rat; for LY, the absence of the transporter may be compensated for by (an)other organic anion transporter(s). PMID:14569083

  7. The Human Gut Microbiome as a Transporter of Antibiotic Resistance Genes between Continents

    PubMed Central

    Bengtsson-Palme, Johan; Angelin, Martin; Huss, Mikael; Kjellqvist, Sanela; Kristiansson, Erik; Palmgren, Helena; Larsson, D. G. Joakim

    2015-01-01

    Previous studies of antibiotic resistance dissemination by travel have, by targeting only a select number of cultivable bacterial species, omitted most of the human microbiome. Here, we used explorative shotgun metagenomic sequencing to address the abundance of >300 antibiotic resistance genes in fecal specimens from 35 Swedish students taken before and after exchange programs on the Indian peninsula or in Central Africa. All specimens were additionally cultured for extended-spectrum beta-lactamase (ESBL)-producing enterobacteria, and the isolates obtained were genome sequenced. The overall taxonomic diversity and composition of the gut microbiome remained stable before and after travel, but there was an increasing abundance of Proteobacteria in 25/35 students. The relative abundance of antibiotic resistance genes increased, most prominently for genes encoding resistance to sulfonamide (2.6-fold increase), trimethoprim (7.7-fold), and beta-lactams (2.6-fold). Importantly, the increase observed occurred without any antibiotic intake. Of 18 students visiting the Indian peninsula, 12 acquired ESBL-producing Escherichia coli, while none returning from Africa were positive. Despite deep sequencing efforts, the sensitivity of metagenomics was not sufficient to detect acquisition of the low-abundant genes responsible for the observed ESBL phenotype. In conclusion, metagenomic sequencing of the intestinal microbiome of Swedish students returning from exchange programs in Central Africa or the Indian peninsula showed increased abundance of genes encoding resistance to widely used antibiotics. PMID:26259788

  8. Novel TetR family transcriptional factor regulates expression of multiple transport-related genes and affects rifampicin resistance in Mycobacterium smegmatis

    PubMed Central

    Liu, Huicong; Yang, Min; He, Zheng-Guo

    2016-01-01

    Transport-related genes significantly affect bacterial antibiotic resistance. However, the effects of these genes and their regulation of bacterial drug resistance in several mycobacterial species, including the fast-growing Mycobacterium smegmatis, the pathogen M. tuberculosis and M. avium have not been clearly characterized. We identified Ms4022 (MSMEG_4022) as a novel TetR family regulator that activates the expression of seven transport-related genes and affects drug resistance in M. smegmatis. Overexpression of Ms4022 inhibited M. smegmatis growth and enhanced mycobacterial resistance to the anti-tuberculosis drug rifampicin (RIF). By contrast, the Ms4022-deleted mycobacterial strain has shown sensitive to RIF. Ms4022 recognized three 19 bp non-palindromic motifs containing a 9 bp conserved region at their 5′ end and it directly regulated seven transport-related genes, which affects mycobacterial resistance to RIF. Overexpression of three of seven transport-related genes (Ms1448, Ms1613, and Ms5278) inhibited the growth of M. smegmatis. This study improves our understanding of the function of mycobacterial transport-related genes and their regulation of bacterial drug resistance. PMID:27271013

  9. Novel TetR family transcriptional factor regulates expression of multiple transport-related genes and affects rifampicin resistance in Mycobacterium smegmatis.

    PubMed

    Liu, Huicong; Yang, Min; He, Zheng-Guo

    2016-01-01

    Transport-related genes significantly affect bacterial antibiotic resistance. However, the effects of these genes and their regulation of bacterial drug resistance in several mycobacterial species, including the fast-growing Mycobacterium smegmatis, the pathogen M. tuberculosis and M. avium have not been clearly characterized. We identified Ms4022 (MSMEG_4022) as a novel TetR family regulator that activates the expression of seven transport-related genes and affects drug resistance in M. smegmatis. Overexpression of Ms4022 inhibited M. smegmatis growth and enhanced mycobacterial resistance to the anti-tuberculosis drug rifampicin (RIF). By contrast, the Ms4022-deleted mycobacterial strain has shown sensitive to RIF. Ms4022 recognized three 19 bp non-palindromic motifs containing a 9 bp conserved region at their 5' end and it directly regulated seven transport-related genes, which affects mycobacterial resistance to RIF. Overexpression of three of seven transport-related genes (Ms1448, Ms1613, and Ms5278) inhibited the growth of M. smegmatis. This study improves our understanding of the function of mycobacterial transport-related genes and their regulation of bacterial drug resistance. PMID:27271013

  10. Mechanisms of hematin crystallization and inhibition by the antimalarial drug chloroquine.

    PubMed

    Olafson, Katy N; Ketchum, Megan A; Rimer, Jeffrey D; Vekilov, Peter G

    2015-04-21

    Hematin crystallization is the primary mechanism of heme detoxification in malaria parasites and the target of the quinoline class of antimalarials. Despite numerous studies of malaria pathophysiology, fundamental questions regarding hematin growth and inhibition remain. Among them are the identity of the crystallization medium in vivo, aqueous or organic; the mechanism of crystallization, classical or nonclassical; and whether quinoline antimalarials inhibit crystallization by sequestering hematin in the solution, or by blocking surface sites crucial for growth. Here we use time-resolved in situ atomic force microscopy (AFM) and show that the lipid subphase in the parasite may be a preferred growth medium. We provide, to our knowledge, the first evidence of the molecular mechanisms of hematin crystallization and inhibition by chloroquine, a common quinoline antimalarial drug. AFM observations demonstrate that crystallization strictly follows a classical mechanism wherein new crystal layers are generated by 2D nucleation and grow by the attachment of solute molecules. We identify four classes of surface sites available for binding of potential drugs and propose respective mechanisms of drug action. Further studies reveal that chloroquine inhibits hematin crystallization by binding to molecularly flat {100} surfaces. A 2-μM concentration of chloroquine fully arrests layer generation and step advancement, which is ∼10(4)× less than hematin's physiological concentration. Our results suggest that adsorption at specific growth sites may be a general mode of hemozoin growth inhibition for the quinoline antimalarials. Because the atomic structures of the identified sites are known, this insight could advance the future design and/or optimization of new antimalarials. PMID:25831526

  11. Chloroquine Analog Interaction with C2- and Iota-Toxin in Vitro and in Living Cells.

    PubMed

    Kronhardt, Angelika; Beitzinger, Christoph; Barth, Holger; Benz, Roland

    2016-01-01

    C2-toxin from Clostridium botulinum and Iota-toxin from Clostridium perfringens belong both to the binary A-B-type of toxins consisting of two separately secreted components, an enzymatic subunit A and a binding component B that facilitates the entry of the corresponding enzymatic subunit into the target cells. The enzymatic subunits are in both cases actin ADP-ribosyltransferases that modify R177 of globular actin finally leading to cell death. Following their binding to host cells' receptors and internalization, the two binding components form heptameric channels in endosomal membranes which mediate the translocation of the enzymatic components Iota a and C2I from endosomes into the cytosol of the target cells. The binding components form ion-permeable channels in artificial and biological membranes. Chloroquine and related 4-aminoquinolines were able to block channel formation in vitro and intoxication of living cells. In this study, we extended our previous work to the use of different chloroquine analogs and demonstrate that positively charged aminoquinolinium salts are able to block channels formed in lipid bilayer membranes by the binding components of C2- and Iota-toxin. Similarly, these molecules protect cultured mammalian cells from intoxication with C2- and Iota-toxin. The aminoquinolinium salts did presumably not interfere with actin ADP-ribosylation or receptor binding but blocked the pores formed by C2IIa and Iota b in living cells and in vitro. The blocking efficiency of pores formed by Iota b and C2IIa by the chloroquine analogs showed interesting differences indicating structural variations between the types of protein-conducting nanochannels formed by Iota b and C2IIa. PMID:27517960

  12. Chloroquine Analog Interaction with C2- and Iota-Toxin in Vitro and in Living Cells

    PubMed Central

    Kronhardt, Angelika; Beitzinger, Christoph; Barth, Holger; Benz, Roland

    2016-01-01

    C2-toxin from Clostridium botulinum and Iota-toxin from Clostridium perfringens belong both to the binary A-B-type of toxins consisting of two separately secreted components, an enzymatic subunit A and a binding component B that facilitates the entry of the corresponding enzymatic subunit into the target cells. The enzymatic subunits are in both cases actin ADP-ribosyltransferases that modify R177 of globular actin finally leading to cell death. Following their binding to host cells’ receptors and internalization, the two binding components form heptameric channels in endosomal membranes which mediate the translocation of the enzymatic components Iota a and C2I from endosomes into the cytosol of the target cells. The binding components form ion-permeable channels in artificial and biological membranes. Chloroquine and related 4-aminoquinolines were able to block channel formation in vitro and intoxication of living cells. In this study, we extended our previous work to the use of different chloroquine analogs and demonstrate that positively charged aminoquinolinium salts are able to block channels formed in lipid bilayer membranes by the binding components of C2- and Iota-toxin. Similarly, these molecules protect cultured mammalian cells from intoxication with C2- and Iota-toxin. The aminoquinolinium salts did presumably not interfere with actin ADP-ribosylation or receptor binding but blocked the pores formed by C2IIa and Iota b in living cells and in vitro. The blocking efficiency of pores formed by Iota b and C2IIa by the chloroquine analogs showed interesting differences indicating structural variations between the types of protein-conducting nanochannels formed by Iota b and C2IIa. PMID:27517960

  13. Transportation.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with transportation and energy use. Its objective is for the student to be able to discuss the implication of energy usage as it applies to the area of transportation. Some topics covered are efficiencies of various transportation…

  14. Highly Loaded Behavior of Kinesins Increases the Robustness of Transport Under High Resisting Loads

    PubMed Central

    Nam, Woochul; Epureanu, Bogdan I.

    2015-01-01

    Kinesins are nano-sized biological motors which walk by repeating a mechanochemical cycle. A single kinesin molecule is able to transport its cargo about 1 μm in the absence of external loads. However, kinesins perform much longer range transport in cells by working collectively. This long range of transport by a team of kinesins is surprising because the motion of the cargo in cells can be hindered by other particles. To reveal how the kinesins are able to accomplish their tasks of transport in harsh intracellular circumstances, stochastic studies on the kinesin motion are performed by considering the binding and unbinding of kinesins to microtubules and their dependence on the force acting on kinesin molecules. The unbinding probabilities corresponding to each mechanochemical state of kinesin are modeled. The statistical characterization of the instants and locations of binding are captured by computing the probability of unbound kinesin being at given locations. It is predicted that a group of kinesins has a more efficient transport than a single kinesin from the perspective of velocity and run length. Particularly, when large loads are applied, the leading kinesin remains bound to the microtubule for long time which increases the chances of the other kinesins to bind to the microtubule. To predict effects of this behavior of the leading kinesin under large loads on the collective transport, the motion of the cargo is studied when the cargo confronts obstacles. The result suggests that the behavior of kinesins under large loads prevents the early termination of the transport which can be caused by the interference with the static or moving obstacles. PMID:25734978

  15. Transfer of chloroquine and desethylchloroquine across the placenta and into milk in Melanesian mothers

    PubMed Central

    Law, Irwin; Ilett, Kenneth F; Hackett, L Peter; Page-Sharp, Madhu; Baiwog, Francesca; Gomorrai, Servina; Mueller, Ivo; Karunajeewa, Harin A; Davis, Timothy M E

    2008-01-01

    AIMS To investigate the transfer of chloroquine and its major bioactive metabolite desethylchloroquine across the placenta and into breast milk. METHODS In Papua New Guinea, chloroquine (CQ; 25 mg base kg−1) is recommended for prophylaxis of malaria during pregnancy, and at the Alexishafen Health Centre women are routinely prescribed CQ at the time of delivery. Fetal-cord and maternal serum samples were collected at delivery (n = 19) and milk samples were collected from day 3 to day 17–21 after delivery (n = 16). CQ and its primary active metabolite desethylchloroquine (DECQ) were quantified by high-performance liquid chromatography. For both CQ and DECQ cord/maternal ratios (C/M) were calculated to characterize placental transfer, and infant exposure via milk was estimated by standard methods. RESULTS The median (interquartile range) C/M was 1.1 (0.9, 1.6) for CQ and 1.2 (0.5, 1.8) for DECQ. The average concentration in milk over the time of sampling was 167 μg l−1 (27, 340) for CQ and 54 μg l−1 (22, 106) for DECQ. Estimated absolute and relative infant doses were 34 μg kg−1 day−1 (7, 50) and 15 μg kg−1 day−1 (4, 26), and 2.3% (0.5, 3.6) and 1.0% (0.4, 2.0) for CQ and DECQ (as CQ equivalents), respectively. CONCLUSION Infant exposure to CQ and DECQ during pregnancy will be similar to that in the maternal circulation, and dependent on maternal dose and frequency. The median CQ + DECQ relative infant dose of 3.2% (as CQ equivalents) was low, confirming that use of CQ during lactation is compatible with breastfeeding. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT The literature on placental and milk transfer of chloroquine and its major bioactive metabolite desethylchloroquine is sparse and incomplete. WHAT THIS STUDY ADDS We have provided data on the transplacental transfer of chloroquine and desethylchloroquine in Melanesian women (n = 19), measured transfer of these drugs into breast milk (n = 16) and estimated absolute and relative infant doses for

  16. A Critical Review of the Effects of Hydroxychloroquine and Chloroquine on the Eye.

    PubMed

    Costedoat-Chalumeau, Nathalie; Dunogué, Bertrand; Leroux, Gaëlle; Morel, Nathalie; Jallouli, Moez; Le Guern, Véronique; Piette, Jean-Charles; Brézin, Antoine P; Melles, Ronald B; Marmor, Michael F

    2015-12-01

    Hydroxychloroquine (HCQ) and chloroquine have been used for more than 50 years to treat systemic lupus erythematosus (SLE) and other rheumatic diseases. In general, these drugs are well tolerated and rarely need to be discontinued because of an adverse systemic reaction. However, both medications can be irreversibly toxic to the retina. A new study indicates that toxicity is not as rare as once believed, but depends critically on daily dosage and duration of use, as well as other risk factors. With attention to dosage and other factors, and with proper screening for early signs of toxicity, HCQ can be prescribed with relative safety even over long periods of time. PMID:25672591

  17. Proline Modulates the Trypanosoma cruzi Resistance to Reactive Oxygen Species and Drugs through a Novel D, L-Proline Transporter

    PubMed Central

    Sayé, Melisa; Miranda, Mariana R.; di Girolamo, Fabio; de los Milagros Cámara, María; Pereira, Claudio A.

    2014-01-01

    Trypanosoma cruzi, the etiological agent of Chagas' disease, has a metabolism largely based on the consumption of glucose and proline. This amino acid is essential for host cells infection and intracellular differentiation. In this work we identified a proline transporter (TcAAAP069) by yeasts complementation assays and overexpression in Trypanosoma cruzi epimastigotes. TcAAAP069 is mono-specific for proline but presents an unusual feature; the lack of stereospecificity, because it is competitively inhibited by the D- enantiomer. Parasites overexpressing TcAAAP069 have an increased intracellular proline concentration, 2.6-fold higher than controls, as a consequence of a higher proline transport rate. Furthermore, augmented proline concentration correlates with an improved resistance to trypanocidal drugs and also to reactive oxygen species including hydrogen peroxide and nitric oxide, emulating natural physiological situations. The IC50s for nifurtimox, benznidazole, H2O2 and NO. were 125%, 68%, 44% and 112% higher than controls, respectively. Finally, proline metabolism generates a higher concentration (48%) of ATP in TcAAAP069 parasites. Since proline participates on essential energy pathways, stress and drug resistance responses, these results provide a novel target for the development of new drugs for the treatments for Chagas' disease. PMID:24637744

  18. A proteomic approach to study Salmonella enterica serovar Typhimurium putative transporter YjeH associated with ceftriaxone resistance

    SciTech Connect

    Hu, Wensi S. Lin, Y.-H.; Shih, C.-C.

    2007-09-28

    Mutant 6B7 of Salmonella enterica serovar Typhimurium has a transposon inserted in the putative transporter gene yjeH and shows a more-than-fourfold reduction in resistance to ceftriaxone. In this report we have used proteomic analysis to compare outer membrane protein profiles between this mutant and its parental strain R200. Five identified proteins were found to be altered. Of these proteins, the level of expression of the porin OmpD was increased and those of the putative outer membrane proteins STM1530 and STM3031, a subunit of the proton-pumping oxidoreductase NuoB and the heat shock protein MopA were decreased in 6B7 strain. Although the function of the yjeH gene remains unknown, a complementation assay suggested that the OmpD, STM1530, STM3031, NuoB, and MopA proteins are associated with ceftriaxone resistance and the expression of these proteins is influenced by the putative transporter gene yjeH in S. enterica serovar Typhimurium.

  19. Effects of stevioside on glucose transport activity in insulin-sensitive and insulin-resistant rat skeletal muscle.

    PubMed

    Lailerd, Narissara; Saengsirisuwan, Vitoon; Sloniger, Julie A; Toskulkao, Chaivat; Henriksen, Erik J

    2004-01-01

    Stevioside (SVS), a natural sweetener extracted from Stevia rebaudiana, has been used as an antihyperglycemic agent. However, little is known regarding its potential action on skeletal muscle, the major site of glucose disposal. Therefore, the purpose of the present study was to determine the effect of SVS treatment on skeletal muscle glucose transport activity in both insulin-sensitive lean (Fa/-) and insulin-resistant obese (fa/fa) Zucker rats. SVS was administered (500 mg/kg body weight by gavage) 2 hours before an oral glucose tolerance test (OGTT). Whereas the glucose incremental area under the curve (IAUC(glucose)) was not affected by SVS in lean Zucker rats, the insulin incremental area under the curve (IAUC(insulin)) and the glucose-insulin index (product of glucose and insulin IAUCs and inversely related to whole-body insulin sensitivity) were decreased (P<.05) by 42% and 45%, respectively. Interestingly, in the obese Zucker rat, SVS also reduced the IAUC(insulin) by 44%, and significantly decreased the IAUC(glucose) (30%) and the glucose-insulin index (57%). Muscle glucose transport was assessed following in vitro SVS treatment. In lean Zucker rats, basal glucose transport in type I soleus and type IIb epitrochlearis muscles was not altered by 0.01 to 0.1 mmol/L SVS. In contrast, 0.1 mmol/L SVS enhanced insulin-stimulated (2 mU/mL) glucose transport in both epitrochlearis (15%) and soleus (48%). At 0.5 mmol/L or higher, the SVS effect was reversed. Similarly, basal glucose transport in soleus and epitrochlearis muscles in obese Zucker rats was not changed by lower doses of SVS (0.01 to 0.1 mmol/L). However, these lower doses of SVS significantly increased insulin-stimulated glucose transport in both obese epitrochlearis and soleus (15% to 20%). In conclusion, acute oral SVS increased whole-body insulin sensitivity, and low concentrations of SVS (0.01 to 0.1 mmol/L) modestly improved in vitro insulin action on skeletal muscle glucose transport in both lean

  20. Current clinical efficacy of chloroquine for the treatment of Plasmodium falciparum infections in urban Dar es Salaam, United Republic of Tanzania.

    PubMed Central

    Premji, Z.; Makwaya, C.; Minjas, J. N.

    1999-01-01

    Reported is the use of a 14-day WHO protocol, which takes into account the clinical, parasitological and haematological responses to antimalarial drugs, to determine the efficacy of chloroquine in the treatment of uncomplicated malaria in young children (n = 200) in urban Dar es Salaam. Chloroquine failure was found in 43% of the children. Of these, 12.5% were considered to be early treatment failures and were given a single dose of sulfadoxine-pyrimethamine. Fever subsided in all children treated with sulfadoxine-pyrimethamine and there were no parasitological failures. In addition, children treated with sulfadoxine-pyrimethamine because of early treatment failure with chloroquine had better haematological recovery than the chloroquine-sensitive group. It is concluded that chloroquine can no longer be considered an effective therapy for P. falciparum malaria in young children in Dar es Salaam. PMID:10534897

  1. The MUC4 mucin mediates gemcitabine resistance of human pancreatic cancer cells via the Concentrative Nucleoside Transporter family

    PubMed Central

    Skrypek, Nicolas; Duchêne, Bélinda; Hebbar, Mohamed; Leteurtre, Emmanuelle; Van Seuningen, Isabelle; Jonckheere, Nicolas

    2013-01-01

    The fluorinated analog of deoxycytidine, Gemcitabine (Gemzar®), is the main chemotherapy in pancreatic cancer, but survival remains weak mainly because of the high resistance of tumors to the drug. Recent works have shown that the mucin MUC4 may confer an advantage to pancreatic tumor cells by modifying their susceptibility to drugs. However, the cellular mechanism(s) responsible for this MUC4-mediated resistance is unknown. The aim of this work was to identify the cellular mechanisms responsible for gemcitabine resistance linked to MUC4 expression. CAPAN-2 and CAPAN-1 adenocarcinomatous pancreatic cancer cell lines were used to establish stable MUC4-deficient clones (MUC4-KD) by shRNA interference. Measurement of the IC50 index using tetrazolium salt test indicated that MUC4-deficient cells were more sensitive to gemcitabine. This was correlated with increased Bax/BclXL ratio and apoptotic cell number. Expression of Equilibrative/Concentrative Nucleoside Transporter (hENT1, hCNT1/3), deoxycytidine kinase (dCK), ribonucleotide reductase (RRM1/2) and Multidrug-resistance Protein (MRP3/4/5) was evaluated by quantitative RT-PCR (qRT-PCR) and Western-blotting. Alteration of MRP3, MRP4, hCNT1 and hCNT3 expression was observed in MUC4-KD cells but only hCNT1 alteration was correlated to MUC4 expression and sensitivity to gemcitabine. Decreased activation of MAPK, JNK and NF-κB pathways was observed in MUC4-deficient cells in which NF-κB pathway was found to play an important role both in sensitivity to gemcitabine and in hCNT1 regulation. Finally and accordingly to our in vitro data, we found that MUC4 expression was conversely correlated to that of hCNT1 in tissues from patients with pancreatic adenocarcinoma. This work describes a new mechanism of pancreatic cancer cell resistance to gemcitabine in which the MUC4 mucin negatively regulates the hCNT1 transporter expression via the NF-κB pathway. Altogether, these data point out to MUC4 and hCNT1 as potential targets

  2. Significant activity of ecdysteroids on the resistance to doxorubicin in mammalian cancer cells expressing the human ABCB1 transporter.

    PubMed

    Martins, Ana; Tóth, Noémi; Ványolós, Attila; Béni, Zoltán; Zupkó, István; Molnár, József; Báthori, Mária; Hunyadi, Attila

    2012-06-14

    Multidrug resistance (MDR) is a major cause of failure of cancer chemotherapy. Fifty-eight ecdysteroids, herbal analogues of the insect molting hormone and their semisynthetic derivatives, were tested for their activity against L5178 mouse T-cell lymphoma cells (non-MDR) and their subcell line transfected with pHa MDR1/A retrovirus overexpressing the human ABCB1 efflux pump (MDR cell line). The compounds showed very low antiproliferative activities but modulated the efflux of rhodamine 123 mediated by the ABCB1 transporter. Roughly depending on the polarity, mild to strong synergism or antagonism was observed by combining ecdysteroids with doxorubicin, and specific structure-activity relationships were also found. Our results show the effect of ecdysteroids on MDR cancer cells for the first time. Less polar derivatives may serve as valuable leads toward a potent and safe resistance modulator. Biological significance of the resistance-increasing activity of the most abundant phytoecdysteroids including 20-hydroxyecdysone is yet to be clarified. PMID:22578055

  3. Environmental Conditions Influence Induction of Key ABC-Transporter Genes Affecting Glyphosate Resistance Mechanism in Conyza canadensis.

    PubMed

    Tani, Eleni; Chachalis, Demosthenis; Travlos, Ilias S; Bilalis, Dimitrios

    2016-01-01

    Conyza canadensis has been reported to be the most frequent weed species that evolved resistance to glyphosate in various parts of the world. The objective of the present study was to investigate the effect of environmental conditions (temperature and light) on the expression levels of the EPSPS gene and two major ABC-transporter genes (M10 and M11) on glyphosate susceptible (GS) and glyphosate resistant (GR) horseweed populations, collected from several regions across Greece. Real-time PCR was conducted to determine the expression level of the aforementioned genes when glyphosate was applied at normal (1×; 533 g·a.e.·ha(-1)) and high rates (4×, 8×), measured at an early one day after treatment (DAT) and a later stage (four DAT) of expression. Plants were exposed to light or dark conditions, at three temperature regimes (8, 25, 35 °C). GR plants were made sensitive when exposed to 8 °C with light; those sensitized plants behaved biochemically (shikimate accumulation) and molecularly (expression of EPSPS and ABC-genes) like the GS plants. Results from the current study show the direct link between the environmental conditions and the induction level of the above key genes that likely affect the efficiency of the proposed mechanism of glyphosate resistance. PMID:27104532

  4. The multidrug-resistance transporter Abcc3 protects NK cells from chemotherapy in a murine model of malignant glioma

    PubMed Central

    Pessina, Sara; Cantini, Gabriele; Kapetis, Dimos; Cazzato, Emanuela; Di Ianni, Natalia; Finocchiaro, Gaetano; Pellegatta, Serena

    2016-01-01

    ABSTRACT Abcc3, a member of the ATP-binding cassette transporter superfamily, plays a role in multidrug resistance. Here, we found that Abcc3 is highly expressed in blood-derived NK cells but not in CD8+ T cells. In GL261 glioma-bearing mice treated with the alkylating agent temozolomide (TMZ) for 5 d, an early increased frequency of NK cells was observed. We also found that Abcc3 is strongly upregulated and functionally active in NK cells from mice treated with TMZ compared to controls. We demonstrate that Abcc3 is critical for NK cell survival during TMZ administration; more importantly, Akt, involved in lymphocyte survival, is phosphorylated only in NK cells expressing Abcc3. The resistance of NK cells to chemotherapy was accompanied by increased migration and homing in the brain at early time points. Cytotoxicity, evaluated by IFNγ production and specific lytic activity against GL261 cells, increased peripherally in the later phases, after conclusion of TMZ treatment. Intra-tumor increase of the NK effector subset as well as in IFNγ, granzymes and perforin-1 expression, were found early and persisted over time, correlating with a profound modulation on glioma microenvironment induced by TMZ. Our findings reveal an important involvement of Abcc3 in NK cell resistance to chemotherapy and have important clinical implications for patients treated with chemo-immunotherapy. PMID:27467914

  5. Environmental Conditions Influence Induction of Key ABC-Transporter Genes Affecting Glyphosate Resistance Mechanism in Conyza canadensis

    PubMed Central

    Tani, Eleni; Chachalis, Demosthenis; Travlos, Ilias S.; Bilalis, Dimitrios

    2016-01-01

    Conyza canadensis has been reported to be the most frequent weed species that evolved resistance to glyphosate in various parts of the world. The objective of the present study was to investigate the effect of environmental conditions (temperature and light) on the expression levels of the EPSPS gene and two major ABC-transporter genes (M10 and M11) on glyphosate susceptible (GS) and glyphosate resistant (GR) horseweed populations, collected from several regions across Greece. Real-time PCR was conducted to determine the expression level of the aforementioned genes when glyphosate was applied at normal (1×; 533 g·a.e.·ha−1) and high rates (4×, 8×), measured at an early one day after treatment (DAT) and a later stage (four DAT) of expression. Plants were exposed to light or dark conditions, at three temperature regimes (8, 25, 35 °C). GR plants were made sensitive when exposed to 8 °C with light; those sensitized plants behaved biochemically (shikimate accumulation) and molecularly (expression of EPSPS and ABC-genes) like the GS plants. Results from the current study show the direct link between the environmental conditions and the induction level of the above key genes that likely affect the efficiency of the proposed mechanism of glyphosate resistance. PMID:27104532

  6. Tivantinib (ARQ 197) exhibits antitumor activity by directly interacting with tubulin and overcomes ABC transporter-mediated drug resistance.

    PubMed

    Aoyama, Aki; Katayama, Ryohei; Oh-Hara, Tomoko; Sato, Shigeo; Okuno, Yasushi; Fujita, Naoya

    2014-12-01

    Tivantinib (ARQ197) was first reported as a highly selective inhibitor of c-MET and is currently being investigated in a phase III clinical trial. However, as recently reported by us and another group, tivantinib showed cytotoxic activity independent of cellular c-MET status and also disrupted microtubule dynamics. To investigate if tivantinib exerts its cytotoxic activity by disrupting microtubules, we quantified polymerized tubulin in cells and xenograft tumors after tivantinib treatment. Consistent with our previous report, tivantinib reduced tubulin polymerization in cells and in mouse xenograft tumors in vivo. To determine if tivantinib directly binds to tubulin, we performed an in vitro competition assay. Tivantinib competitively inhibited colchicine but not vincristine or vinblastine binding to purified tubulin. These results imply that tivantinib directly binds to the colchicine binding site of tubulin. To predict the binding mode of tivantinib with tubulin, we performed computer simulation of the docking pose of tivantinib with tubulin using GOLD docking program. Computer simulation predicts tivantinib fitted into the colchicine binding pocket of tubulin without steric hindrance. Furthermore, tivantinib showed similar IC50 values against parental and multidrug-resistant cells. In contrast, other microtubule-targeting drugs, such as vincristine, paclitaxel, and colchicine, could not suppress the growth of cells overexpressing ABC transporters. Moreover, the expression level of ABC transporters did not correlate with the apoptosis-inducing ability of tivantinib different from other microtubule inhibitor. These results suggest that tivantinib can overcome ABC transporter-mediated multidrug-resistant tumor cells and is potentially useful against various tumors. PMID:25313010

  7. Multiple transport systems mediate virus-induced acquired resistance to oxidative stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper, we report the phenomenon of acquired cross-tolerance to oxidative (UV-C and H2O2) stress in Nicotiana benthamiana plants infected with Potato virus X (PVX) and investigate the functional expression of transport systems in mediating this phenomenon. By combining multiple approaches, we...

  8. Influence of ATP-binding cassette transporters in root exudation of phytoalexins, signals, and disease resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The roots of plants secrete compounds as a way to exchange information with organ-isms living in the soil. Here, we report the involvement of seven root-expressed ATP-binding cassette (ABC) transporters corresponding to both full and half-size molecules (Atabcg36, Atabcg37, Atabcc5, Atabcf1, Atabcf3...

  9. Negative differential resistance in GeSi core-shell transport junctions: the role of local sp(2) hybridization.

    PubMed

    Liu, Nuo; Zhang, Lei; Chen, Xiaobin; Kong, Xianghua; Zheng, Xiaohong; Guo, Hong

    2016-09-21

    We report a theoretical investigation of nonlinear quantum transport properties of Au/GeSi/Au junctions. For GeSi semiconducting core-shell structures brought into contact with Au electrodes, a very unusual behavior is that the tunneling transport is on-resonance right at equilibrium. This resonance is not due to the alignment of a quantum level in GeSi to the electrochemical potential of Au, but due to the alignment of very sharp DOS features - hot spots, localized at the two Au/GeSi interfaces of the device. An applied bias voltage shifts the hot spots relative to each other which gives rise to substantial negative differential resistance (NDR). The hot spots localized at the two interfaces were found to be due to the unbonded pz orbital of a sp(2) hybridized interface Si atom which is surrounded by three non-sp(2) hybridized neighbors. The mechanism of inducing hot spots and NDR by a local structure unit is not limited to the GeSi. The results suggest an interesting scheme for constructing NDR devices by orbital manipulation, to be more explicit, for example, by designing local structural units having unbonded orbitals at the interfaces between electrodes and the central region of the transport junction. PMID:27546305

  10. Transport Properties of Bulk Thermoelectrics An International Round-Robin Study, Part I: Seebeck Coefficient and Electrical Resistivity

    SciTech Connect

    Wang, Hsin; Porter, Wallace D; Bottner, Harold; Konig, Jan; Chen, Lidong; Bai, Shengqiang; Tritt, Terry M.; Mayolett, Alex; Senawiratne, Jayantha; Smith, Charlene; Harris, Fred; Gilbert, Partricia; Sharp, Jeff; Lo, Jason; Keinke, Holger; Kiss, Laszlo I.

    2013-01-01

    Recent research and development of high temperature thermoelectric materials has demonstrated great potential of converting automobile exhaust heat directly into electricity. Thermoelectrics based on classic bismuth telluride have also started to impact the automotive industry by enhancing air conditioning efficiency and integrated cabin climate control. In addition to engineering challenges of making reliable and efficient devices to withstand thermal and mechanical cycling, the remaining issues in thermoelectric power generation and refrigeration are mostly materials related. The figure-of-merit, ZT, still needs to improve from the current value of 1.0 - 1.5 to above 2 to be competitive to other alternative technologies. In the meantime, the thermoelectric community could greatly benefit from the development of international test standards, improved test methods and better characterization tools. Internationally, thermoelectrics have been recognized by many countries as an important area for improving energy efficiency. The International Energy Agency (IEA) group under the implementing agreement for Advanced Materials for Transportation (AMT) identified thermoelectric materials as an important area in 2009. This paper is Part I of the international round-robin testing of transport properties of bulk thermoelectrics. The main focuses in Part I are on two electronic transport properties: Seebeck coefficient and electrical resistivity.

  11. ‘Metal’-like transport in high-resistance, high aspect ratio two-dimensional electron gases

    NASA Astrophysics Data System (ADS)

    Backes, Dirk; Hall, Richard; Pepper, Michael; Beere, Harvey; Ritchie, David; Narayan, Vijay

    2016-01-01

    We investigate the striking absence of strong localisation observed in mesoscopic two-dimensional electron gases (2DEGs) (Baenninger et al 2008 Phys. Rev. Lett. 100 016805, Backes et al 2015 arXiv:1505.03444) even when their resistivity ρ \\gg h/{{e}2} . In particular, we try to understand whether this phenomenon originates in quantum many-body effects, or simply percolative transport through a network of electron puddles. To test the latter scenario, we measure the low temperature (low-T) transport properties of long and narrow 2DEG devices in which percolation effects should be heavily suppressed in favour of Coulomb blockade. Strikingly we find no indication of Coulomb blockade and that the high-ρ, low-T transport is exactly similar to that previously reported in mesoscopic 2DEGs with different geometries. Remarkably, we are able to induce a ‘metal’-insulator transition (MIT) by applying a perpendicular magnetic field B. We present a picture within which these observations fit into the more conventional framework of the 2D MIT.

  12. Transport Properties of Bulk Thermoelectrics—An International Round-Robin Study, Part I: Seebeck Coefficient and Electrical Resistivity

    NASA Astrophysics Data System (ADS)

    Wang, Hsin; Porter, Wallace D.; Böttner, Harald; König, Jan; Chen, Lidong; Bai, Shengqiang; Tritt, Terry M.; Mayolet, Alex; Senawiratne, Jayantha; Smith, Charlene; Harris, Fred; Gilbert, Patricia; Sharp, Jeff W.; Lo, Jason; Kleinke, Holger; Kiss, Laszlo

    2013-04-01

    Recent research and development of high-temperature thermoelectric materials has demonstrated great potential for converting automobile exhaust heat directly into electricity. Thermoelectrics based on classic bismuth telluride have also started to impact the automotive industry by enhancing air-conditioning efficiency and integrated cabin climate control. In addition to engineering challenges of making reliable and efficient devices to withstand thermal and mechanical cycling, the remaining issues in thermoelectric power generation and refrigeration are mostly materials related. The dimensionless figure of merit, ZT, still needs to be improved from the current value of 1.0 to 1.5 to above 2.0 to be competitive with other alternative technologies. In the meantime, the thermoelectric community could greatly benefit from the development of international test standards, improved test methods, and better characterization tools. Internationally, thermoelectrics have been recognized by many countries as a key component for improving energy efficiency. The International Energy Agency (IEA) group under the Implementing Agreement for Advanced Materials for Transportation (AMT) identified thermoelectric materials as an important area in 2009. This paper is part I of the international round-robin testing of transport properties of bulk thermoelectrics. The main foci in part I are the measurement of two electronic transport properties: Seebeck coefficient and electrical resistivity.

  13. A combination of curcumin with either gramicidin or ouabain selectively kills cells that express the multidrug resistance-linked ABCG2 transporter.

    PubMed

    Rao, Divya K; Liu, Haiyan; Ambudkar, Suresh V; Mayer, Michael

    2014-11-01

    This paper introduces a strategy to kill selectively multidrug-resistant cells that express the ABCG2 transporter (also called breast cancer resistance protein, or BCRP). The approach is based on specific stimulation of ATP hydrolysis by ABCG2 transporters with subtoxic doses of curcumin combined with stimulation of ATP hydrolysis by Na(+),K(+)-ATPase with subtoxic doses of gramicidin A or ouabain. After 72 h of incubation with the drug combinations, the resulting overconsumption of ATP by both pathways inhibits the efflux activity of ABCG2 transporters, leads to depletion of intracellular ATP levels below the viability threshold, and kills resistant cells selectively over cells that lack ABCG2 transporters. This strategy, which was also tested on a clinically relevant human breast adenocarcinoma cell line (MCF-7/FLV1), exploits the overexpression of ABCG2 transporters and induces caspase-dependent apoptotic cell death selectively in resistant cells. This work thus introduces a novel strategy to exploit collateral sensitivity (CS) with a combination of two clinically used compounds that individually do not exert CS. Collectively, this work expands the current knowledge on ABCG2-mediated CS and provides a potential strategy for discovery of CS drugs against drug-resistant cancer cells. PMID:25253691

  14. Salinomycin overcomes ABC transporter-mediated multidrug and apoptosis resistance in human leukemia stem cell-like KG-1a cells

    SciTech Connect

    Fuchs, Dominik; Daniel, Volker; Sadeghi, Mahmoud; Opelz, Gerhard; Naujokat, Cord

    2010-04-16

    Leukemia stem cells are known to exhibit multidrug resistance by expression of ATP-binding cassette (ABC) transporters which constitute transmembrane proteins capable of exporting a wide variety of chemotherapeutic drugs from the cytosol. We show here that human promyeloblastic leukemia KG-1a cells exposed to the histone deacetylase inhibitor phenylbutyrate resemble many characteristics of leukemia stem cells, including expression of functional ABC transporters such as P-glycoprotein, BCRP and MRP8. Consequently, KG-1a cells display resistance to the induction of apoptosis by various chemotherapeutic drugs. Resistance to apoptosis induction by chemotherapeutic drugs can be reversed by cyclosporine A, which effectively inhibits the activity of P-glycoprotein and BCRP, thus demonstrating ABC transporter-mediated drug resistance in KG-1a cells. However, KG-1a are highly sensitive to apoptosis induction by salinomycin, a polyether ionophore antibiotic that has recently been shown to kill human breast cancer stem cell-like cells and to induce apoptosis in human cancer cells displaying multiple mechanisms of drug and apoptosis resistance. Whereas KG-1a cells can be adapted to proliferate in the presence of apoptosis-inducing concentrations of bortezomib and doxorubicin, salinomycin does not permit long-term adaptation of the cells to apoptosis-inducing concentrations. Thus, salinomycin should be regarded as a novel and effective agent for the elimination of leukemia stem cells and other tumor cells exhibiting ABC transporter-mediated multidrug resistance.

  15. Response of microscale turbulence and transport to the evolution of resistive magnetohydrodynamic magnetic island

    SciTech Connect

    Li, Jiquan Kishimoto, Y.; Wang, Z. X.

    2014-02-15

    Nonlinear evolution of microscale turbulence interacting with a naturally growing MHD magnetic island is simulated based on a Landau-fluid model. Here, we report on a new short wavelength magnetic-island-induced ion temperature gradient (ITG) instability triggered by a critical threshold of magnetic island width in multiscale turbulence, which is referred to as sw-MITG mode. The sw-MITG mode is characterized by a substantially low stability threshold and a global structure propagating along the ion diamagnetic drift direction. Its generation results from the response of microscale fluctuations to turbulent cross-field heat transport associated with increasing boundary layer width about the island separatrix. An intermittency of heat transport is caused by the sw-MITG mode interacting with dynamical magnetic island and microturbulence.

  16. Temporal trends in prevalence of Plasmodium falciparum drug resistance alleles over two decades of changing antimalarial policy in coastal Kenya.

    PubMed

    Okombo, John; Kamau, Alice W; Marsh, Kevin; Sutherland, Colin J; Ochola-Oyier, Lynette Isabella

    2014-12-01

    Molecular surveillance of drug resistance markers through time provides crucial information on genomic adaptations, especially in parasite populations exposed to changing drug pressures. To assess temporal trends of established genotypes associated with tolerance to clinically important antimalarials used in Kenya over the last two decades, we sequenced a region of the pfcrt locus encompassing codons 72-76 of the Plasmodium falciparum chloroquine resistance transporter, full-length pfmdr1 - encoding multi-drug resistance protein, P-glycoprotein homolog (Pgh1) and pfdhfr encoding dihydrofolate reductase, in 485 archived Plasmodium falciparum positive blood samples collected in coastal Kenya at four different time points between 1995 and 2013. Microsatellite loci were also analyzed to compare the genetic backgrounds of parasite populations circulating before and after the withdrawal of chloroquine and sulfadoxine/pyrimethamine. Our results reveal a significant increase in the prevalence of the pfcrt K76 wild-type allele between 1995 and 2013 from 38% to 81.7% (p < 0.0001). In contrast, we noted a significant decline in wild-type pfdhfr S108 allele (p < 0.0001) culminating in complete absence of this allele in 2013. We also observed a significant increase in the prevalence of the wild-type pfmdr1 N86/Y184/D1246 haplotype from 14.6% in 1995 to 66.0% in 2013 (p < 0.0001) and a corresponding decline of the mutant pfmdr1 86Y/184Y/1246Y allele from 36.4% to 0% in 19 years (p < 0.0001). We also show extensive genetic heterogeneity among the chloroquine-sensitive parasites before and after the withdrawal of the drug in contrast to a selective sweep around the triple mutant pfdhfr allele, leading to a mono-allelic population at this locus. These findings highlight the importance of continual surveillance and characterization of parasite genotypes as indicators of the therapeutic efficacy of antimalarials, particularly in the context of changes in malaria treatment

  17. Attenuation of high sucrose diet–induced insulin resistance in ABC transporter deficient white mutant of Drosophila melanogaster

    PubMed Central

    Navrotskaya, Valeriya; Oxenkrug, Gregory; Vorobyova, Lyudmila; Summergrad, Paul

    2016-01-01

    Exposure to high sugar diet (HSD) is an experimental model of insulin resistance (IR) and type 2 diabetes (T2D) in mammals and insects. In Drosophila, HSD-induced IR delays emergence of pupae from larvae and eclosion of imago from pupae. Understanding of mechanisms of IR/T2D is essential for refining T2D prevention and treatment strategies. Dysregulation of tryptophan (Trp)-kynurenine (Kyn) pathway was suggested as one of the mechanisms of IR/T2D development. Rate-limiting enzyme of Trp-Kyn pathway in Drosophila is Trp 2,3-dioxygenase (TDO), an evolutionary conserved ortholog of human TDO. We previously reported attenuation of HSD-induced IR in vermilion mutants with inactive TDO. Conversion of Trp to Kyn is regulated not only by TDO activity but by intracellular Trp transport via ATP-binding cassette (ABC) transporter encoded by white gene in Drosophila. In order to evaluate the possible impact of deficient intracellular Trp transport on the inducement of IR by HSD, we compared the effect of HSD on pre-imago development in wild type flies, Canton-Special (C-S), and C-S flies containing white gene, white (C-S). Presence of white gene attenuated (by 50%) HSD-induced delay of pupae emergence from larvae and female and male imago eclosion from pupae. Present study together with our earlier report reveals that both decreased TDO activity (due to vermilion gene mutation) or deficient Trp transport into cell without affecting TDO levels (due to white gene mutation) attenuate HSD-induced development of IR in Drosophila model of T2D. Our data provide further support for hypothesis that dysregulation of Trp-Kyn pathway is one of the pathophysiological mechanisms and potential target for early diagnosis, prevention and treatment of IR/T2D. PMID:27375855

  18. The cloning and characterization of two ammonium transporters in the salt-resistant green alga, Dunaliella viridis.

    PubMed

    Song, Ting; Gao, Qiang; Xu, Zhengkai; Song, Rentao

    2011-10-01

    Ammonium (NH(4) (+)) transport is a key process in nitrogen metabolism. To elucidate the role of ammonium transporters in the nitrogen consumption of the salt-resistant green alga, Dunaliella viridis, two ammonium transporter genes, DvAMT1;1 and DvAMT1;2, were isolated from cDNA libraries of D. viridis. DvAMT1;1 and DvAMT1;2 share only 40% amino acid identity, indicating that they have highly divergent coding sequences. Functional complementation in a yeast mutant defective in ammonium uptake indicated that both DvAMT1;1 and DvAMT1;2 were functional ammonium transporters. Quantitative RT-PCR showed similar expression patterns, but different transcript abundance levels, for DvAMT1;1 and DvAMT1;2 under different nitrogen conditions. Both were induced at low nitrogen and inhibited at high nitrogen concentrations, especially when NH(4) (+) was the nitrogen source. At the transcriptional level, DvAMT1;1 was diurnally regulated, while DvAMT1;2 was not. In addition, under NaCl concentrations that ranged from 0.5 to 3 M, DvAMT1;1 was down-regulated at the higher salt conditions; conversely, DvAMT1;2 maintained a relatively low, but stable, transcript abundance. The observed differences in transcriptional regulation of DvAMT1;1 and DvAMT1;2 are indicative of their diverse physiological functions in D. viridis. PMID:21153924

  19. Aquatic electrical resistivity imaging of rainfall-driven solute transport in contaminated wetlands

    NASA Astrophysics Data System (ADS)

    Slater, L.; Mansoor, N.

    2007-05-01

    A continuous aquatic electrical resistivity imaging (ERI) technique, using floating electrodes and a shallow-draft paddleboat, was employed to predict spatial and temporal patterns of pore-fluid conductivity in wetland soils of a contaminated, shallow-water wetland. ERI measurements were obtained with marine-acquisition software and a multi-channel resistivity instrument at six times over a four month period, covering a 10 square kilometer grid. A set of 10 simultaneous reception channel measurements were continuously recorded every two seconds yielding an average of 13,000 measurements per survey. Three dimensional inversion was carried out to determine the conductivity distribution of the subsurface using the smoothness-constrained least-squares optimization method. The continuously recorded surface water depth and conductivity were entered as known information in the inversion and measurement error (further constraining the inversion) estimated using a tie point technique. Pore- fluid conductivity estimates were constrained using surface conduction measurements obtained from laboratory experiments on soils extracted from the wetland, as well as a correction for temporal and spatial temperature variations based on direct surface water temperature measurements and existing data on the thermal characteristics of peat soils. The study demonstrated that: (1) continuous aquatic ERI is an ideal method for resolving the resistivity structure of wetland sediments covered by a shallow (less than 1 m) surface water layer, (2) temperature variations must be considered in such shallow monitoring studies as they may otherwise have the most significant influence on the results, and (3) surface conduction is significant in marsh soils and must be accounted for if subsurface conductivity models are to be reliably interpreted in terms of pore-fluid chemistry. In the field example presented here, changes in pore-water conductivity estimated from inverted models suggest that

  20. Heterogeneous reactive transport under unsaturated transient conditions characterized by 3D electrical resistivity tomography and advanced lysimeter methods

    NASA Astrophysics Data System (ADS)

    Wehrer, Markus; Slater, Lee

    2015-04-01

    Our ability to predict flow and transport processes in the unsaturated critical zone is considerably limited by two characteristics: heterogeneity of flow and transience of boundary conditions. The causes of heterogeneous flow and transport are fairly well understood, yet the characterization and quantification of such processes in natural profiles remains challenging. This is due to current methods of observation, such as staining and isotope tracers, being unable to observe multiple events on the same profile and offering limited spatial information. In our study we demonstrate an approach to characterize preferential flow and transport processes applying a combination of geoelectrical methods and advanced lysimeter techniques. On an agricultural soil profile, which was transferred undisturbed into a lysimeter container, we systematically applied a variety of input flow boundary conditions, resembling natural precipitation events. We measured breakthroughs of a conservative tracer and of nitrate, originating from the application of a slow release fertilizer and serving as a reactive tracer. Flow and transport in the soil column were observed using electrical resistivity tomography (ERT), tensiometers, water content probes and a multicompartment suction plate (MSP). These techniques allowed a direct validation of water content dynamics and tracer breakthrough under transient boundary conditions characterized noninvasively by ERT. We were able to image the advancing infiltration front and the advancing front of tracer and nitrate using time lapse ERT. Water content changes associated with the advancing infiltration front dominated over pore fluid conductivity changes during short term precipitation events. Conversely, long-term displacement of the solute fronts was monitored during periods of constant water content in between infiltration events. We observed preferential flow phenomena through ERT and through the MSP, which agreed in general terms. The preferential

  1. The ABC transporter AnrAB contributes to the innate resistance of Listeria monocytogenes to nisin, bacitracin, and various beta-lactam antibiotics.

    PubMed

    Collins, Barry; Curtis, Nicola; Cotter, Paul D; Hill, Colin; Ross, R Paul

    2010-10-01

    A mariner transposon bank was used to identify loci that contribute to the innate resistance of Listeria monocytogenes to the lantibiotic nisin. In addition to highlighting the importance of a number of loci previously associated with nisin resistance (mprF, virRS, and telA), a nisin-sensitive phenotype was associated with the disruption of anrB (lmo2115), a gene encoding the permease component of an ABC transporter. The contribution of anrB to nisin resistance was confirmed by the creation of nonpolar deletion mutants. The loss of this putative multidrug resistance transporter also greatly enhanced sensitivity to bacitracin, gallidermin, and a selection of β-lactam antibiotics. A comparison of the relative antimicrobial sensitivities of a number of mutants established the ΔanrB strain as being one of the most bacitracin-sensitive L. monocytogenes strains identified to date. PMID:20643901

  2. Transport properties of bare and hydrogenated zigzag silicene nanoribbons: Negative differential resistances and perfect spin-filtering effects

    SciTech Connect

    Yang, X. F.; Liu, Y. S. Feng, J. F.; Wang, X. F.; Zhang, C. W.; Chi, F.

    2014-09-28

    Ab initio calculations are performed to investigate the spin-polarized transport properties of the bare and hydrogenated zigzag silicene nanoribbons (ZSiNRs). The results show that the ZSiNRs with symmetric (asymmetric) edges prefer the ferromagnetic (antiferromagnetic) as their ground states with the semiconductor properties, while the accordingly antiferromagnetic (ferromagnetic) states exhibit the metallic behaviors. These facts result in a giant magnetoresistance behavior between the ferromagnetic and antiferromagnetic states in the low bias-voltage regime. Moreover, in the ferromagnetic ZSiNRs with asymmetric edges, a perfect spin-filtering effect with 100% positive electric current polarization can be achieved by altering the bias voltage. In addition, we also find that the negative differential resistances prefer the metastable states. The findings here indicate that the asymmetric and symmetric ZSiNRs are promising materials for spintronic applications.

  3. Reduced workfunction intermetallic seed layers allow growth of porous n-GaN and low resistivity, ohmic electron transport.

    PubMed

    Bilousov, Oleksandr V; Carvajal, Joan J; Drouin, Dominique; Mateos, Xavier; Díaz, Francesc; Aguiló, Magdalena; O'Dwyer, Colm

    2012-12-01

    Porous GaN crystals have been successfully grown and electrically contacted simultaneously on Pt- and Au-coated silicon substrates as porous crystals and as porous layers. By the direct reaction of metallic Ga and NH(3) gas through chemical vapor deposition, intermetallic metal-Ga alloys form at the GaN-metal interface, allowing vapor-solid-solid seeding and subsequent growth of porous GaN. Current-voltage and capacitance-voltage measurements confirm that the intermetallic seed layers prevent interface oxidation and give a high-quality reduced workfunction contact that allows exceptionally low contact resistivities. Additionally, the simultaneous formation of a lower workfunction intermetallic permits ohmic electron transport to n-type GaN grown using high workfunction metals that best catalyze the formation of porous GaN layers and may be employed to seed and ohmically contact a range of III-N compounds and alloys for broadband absorption and emission. PMID:23167596

  4. Effects of pristane alone or combined with chloroquine on macrophage activation, oxidative stress, and TH1/TH2 skewness.

    PubMed

    Ouyang, Qiufang; Huang, Ziyang; Wang, Zhenhua; Chen, Xiaoqing; Ni, Jingqin; Lin, Ling

    2014-01-01

    We investigated the protective role of chloroquine against pristane-induced macrophage activation, oxidative stress, and Th1/Th2 skewness in C57BL/6J mice. Those mice were treated with pristane alone or combined with chloroquine. Hematological and biochemical parameters, macrophage phagocytic function, the oxidant/antioxidant index, cytokine for IFN-γ, TNF-α, IL-4, and IL-6, and the isotypes of IgG2a and IgG1 were determined. And the expression of T-bet/GATA-3 and IL-12/IL-10 mRNA in spleen were analyzed by real-time PCR. We found that pristane treatment for a period of 12 or 24 weeks triggered macrophage activation syndrome, characterized by hemophagocytosis in spleen and peripheral blood, enhanced lipid phagocytosis by peritoneal macrophages in vitro, erythropenia and leucopenia, increased anti-Smith, lactic dehydrogenase, triglyceride, and ferritin, as well as hypercytokinemia of IFN-γ, TNF-α, IL-4, and IL-6. In parallel, a significant increase in lipid peroxidation and a decrease in superoxide dismutase, glutathione, and catalase activity, as well as a skewed Th1/Th2 balance in spleen, were observed. However, chloroquine supplementation showed a remarkable amelioration of these abnormalities. Our data indicate that pristane administration induces macrophage activation, oxidative stress, and Th1/Th2 skewness, which can be attenuated by chloroquine. PMID:25136646

  5. Prospects of intermittent preventive treatment of adults against malaria in areas of seasonal and unstable malaria transmission, and a possible role for chloroquine.

    PubMed

    Giha, Hayder A

    2010-04-01

    Chloroquine (CQ) is outmoded as an antimalarial drug in most of the malarial world because of the high resistance rate of parasites. The parasite resistance to CQ is attributed to pfcrt/pfmdr1 gene mutations. Recent studies showed that parasites with mutations of pfcrt/pfmdr1 genes are less virulent, and that those with dhfr/dhps mutations are more susceptible to host immune clearance; the former and latter mutations are linked. In the era of artemisinin-based combination therapy, the frequency of pfcrt/pfmdr1 wild variants is expected to rise. In areas of unstable malaria transmission, the unpredictable severe epidemics of malaria and epidemics of severe malaria could result in high mortality rate among the semi-immune population. With this in mind, the use of CQ for intermittent preventive treatment of adults (IPTa) is suggested as a feasible control measure to reduce malaria mortality in adults and older children without reducing uncomplicated malaria morbidity. The above is discussed in a multidisciplinary approach validating the deployment of molecular techniques in malaria control and showing a possible role for CQ as a rescue drug after being abandoned. PMID:20307217

  6. Tolerance to biodegraded crude oil in marine invertebrate embryos and larvae is associated with expression of a multixenobiotic resistance transporter.

    PubMed

    Hamdoun, Amro M; Griffin, Fred J; Cherr, Gary N

    2002-11-13

    The toxicity of water-soluble fractions of biodegraded crude oil (BWSF) to embryos and larvae of two marine invertebrates, the white sea urchin (Lytechinus anamesus) and the fat innkeeper (Urechis caupo), was studied. Santa Barbara Channel crude oil was artificially weathered and subjected to biodegradation using a mixed microbe culture obtained from natural oil seep sites. The degradation culture inoculated with seep sediment microbes accumulated 43.7 microg/l water-soluble hydrocarbons. In contrast water-soluble fractions from the non-degraded cultures (NWSF) only accumulated 3.05 microg/l. BWSF proved deleterious to Lytechinus embryo development at low concentrations (EC50 = 0.33 mg/l) but was essentially non-toxic to Urechis embryos/larvae up to 3.0 mg/l. An established mechanism for handling of a wide array of xenobiotics in Urechis embryos is the multixenobiotoic resistance transporter multixenobiotic response (MXR, also known as multidrug resistance, MDR). This mechanism is primarily mediated by ATP-dependent, efflux pumps that extrude a wide array of xenobiotic compounds. In this study, we show that Lytechinus larvae do not appear to express MXR efflux protein nor MXR mediated dye efflux capacity. In contrast, BWSF acts as a competitive inhibitor of MXR transport-mediated dye efflux in Urechis larvae. These results suggest that MXR may be an important mechanism for extrusion of the by-products of crude oil degradation by microbes, and that the level of its expression may determine the susceptibility of organisms to degraded oil hydrocarbons. PMID:12297376

  7. A Small Multidrug Resistance-like Transporter Involved in the Arabinosylation of Arabinogalactan and Lipoarabinomannan in Mycobacteria*

    PubMed Central

    Larrouy-Maumus, Gérald; Škovierová, Henrieta; Dhouib, Rabeb; Angala, Shiva Kumar; Zuberogoitia, Sophie; Pham, Ha; Villela, Anne Drumond; Mikušová, Katarina; Noguera, Audrey; Gilleron, Martine; Valentínová, Lucia; Korduláková, Jana; Brennan, Patrick. J.; Puzo, Germain; Nigou, Jérôme; Jackson, Mary

    2012-01-01

    The biosynthesis of the major cell envelope glycoconjugates of Mycobacterium tuberculosis is topologically split across the plasma membrane, yet nothing is known of the transporters required for the translocation of lipid-linked sugar donors and oligosaccharide intermediates from the cytoplasmic to the periplasmic side of the membrane in mycobacteria. One of the mechanisms used by prokaryotes to translocate lipid-linked phosphate sugars across the plasma membrane relies on translocases that share resemblance with small multidrug resistance transporters. The presence of an small multidrug resistance-like gene, Rv3789, located immediately upstream from dprE1/dprE2 responsible for the formation of decaprenyl-monophosphoryl-β-d-arabinose (DPA) in the genome of M. tuberculosis led us to investigate its potential involvement in the formation of the major arabinosylated glycopolymers, lipoarabinomannan (LAM) and arabinogalactan (AG). Disruption of the ortholog of Rv3789 in Mycobacterium smegmatis resulted in a reduction of the arabinose content of both AG and LAM that accompanied the accumulation of DPA in the mutant cells. Interestingly, AG and LAM synthesis was restored in the mutant not only upon expression of Rv3789 but also upon that of the undecaprenyl phosphate aminoarabinose flippase arnE/F genes from Escherichia coli. A bacterial two-hybrid system further indicated that Rv3789 interacts in vivo with the galactosyltransferase that initiates the elongation of the galactan domain of AG. Biochemical and genetic evidence is thus consistent with Rv3789 belonging to an AG biosynthetic complex, where its role is to reorient DPA to the periplasm, allowing this arabinose donor to then be used in the buildup of the arabinan domains of AG and LAM. PMID:23038254

  8. Numerical investigation of interfacial transport resistance due to water droplets in proton exchange membrane fuel cell air channels

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa; Kandlikar, Satish G.

    2013-12-01

    Oxygen transport resistance at the air flow channel and gas diffusion layer (GDL) interface is needed in modelling the performance of a proton exchange membrane fuel cell (PEMFC). This resistance is expressed through the non-dimensional Sherwood number (Sh). The effect of the presence of a droplet on Sh is studied numerically in an isolated air flow channel using a commercially available package, COMSOL Multiphysics®. A droplet is represented as a solid obstruction placed on the GDL-channel interface and centred along the channel width. The effect of a single droplet is first studied for a range of superficial mean air velocities and droplet sizes. Secondly, the effect of droplet spacing on Sh is studied through simulations of two consecutive droplets. Lastly, multiple droplets in a row are studied as a more representative case of a PEMFC air flow channel. The results show that the droplets significantly increase Sh above the fully developed value in the wake region. This enhancement increases with the number of droplets, droplet size, and superficial mean air velocity. Moreover, the analogy between mass and heat transfer is investigated by comparing Sh to the equivalent Nusselt number.

  9. Charge transport mechanisms in Schottky diodes based on low-resistance CdTe:Mn

    SciTech Connect

    Kosyachenko, L. A. Yurtsenyuk, N. S.; Rarenko, I. M.; Sklyarchuk, V. M.; Sklyarchuk, O. F.; Zakharuk, Z. I.; Grushko, E. V.

    2013-07-15

    CdTe:Mn crystals with a resistivity of {approx}1 {Omega} cm at 300 K and Schottky diodes based on them are investigated. The electrical conductivity of the material and its temperature variations are explained in terms of the statistics of electrons and holes in semiconductors with allowance for the compensation processes. The ionization energy and the degree of compensation of the donors responsible for the conductivity are determined. It is shown that, in the case of forward connection and low reverse biases, the currents in Au/CdTe:Mn Schottky diode are determined by generation-recombination processes in the space-charge region. At higher reverse biases (above 1.5-2 V) the excess current is caused by electron tunneling from the metal to the semiconductor, and at even higher voltages (>6-7 V) an additional increase in the reverse current due to avalanche processes is observed.

  10. Assessing Resistance to Change During Shifting from Legacy to Open Web-Based Systems in the Air Transport Industry

    NASA Astrophysics Data System (ADS)

    Brewer, Denise

    The air transport industry (ATI) is a dynamic, communal, international, and intercultural environment in which the daily operations of airlines, airports, and service providers are dependent on information technology (IT). Many of the IT legacy systems are more than 30 years old, and current regulations and the globally distributed workplace have brought profound changes to the way the ATI community interacts. The purpose of the study was to identify the areas of resistance to change in the ATI community and the corresponding factors in change management requirements that minimize product development delays and lead to a successful and timely shift from legacy to open web-based systems in upgrading ATI operations. The research questions centered on product development team processes as well as the members' perceived need for acceptance of change. A qualitative case study approach rooted in complexity theory was employed using a single case of an intercultural product development team dispersed globally. Qualitative data gathered from questionnaires were organized using Nvivo software, which coded the words and themes. Once coded, themes emerged identifying the areas of resistance within the product development team. Results of follow-up interviews with team members suggests that intercultural relationship building prior to and during project execution; focus on common team goals; and, development of relationships to enhance interpersonal respect, understanding and overall communication help overcome resistance to change. Positive social change in the form of intercultural group effectiveness evidenced in increased team functioning during major project transitions is likely to result when global managers devote time to cultural understanding.

  11. Evaluation of transport of common antiepileptic drugs by human multidrug resistance-associated proteins (MRP1, 2 and 5) that are overexpressed in pharmacoresistant epilepsy.

    PubMed

    Luna-Tortós, Carlos; Fedrowitz, Maren; Löscher, Wolfgang

    2010-06-01

    Resistance to antiepileptic drugs (AEDs) is one of the most serious problems in the treatment of epilepsy. Accumulating experimental evidence suggests that increased expression of the drug efflux transporter P-glycoprotein (Pgp) at the blood-brain barrier may be involved in the mechanisms leading to AED resistance. In addition to Pgp, increased expression of several multidrug resistance-associated proteins (MRPs) has been determined in epileptogenic brain regions of patients with pharmacoresistant epilepsy. However, it is not known whether AEDs are substrates for MRPs. In the present experiments, we evaluated whether common AEDs are transported by human MRPs (MRP1, 2 and 5) that are overexpressed in AED resistant epilepsy. For this purpose, we used a highly sensitive assay (concentration equilibrium transport assay; CETA) in polarized kidney cell lines (LLC, MDCKII) transfected with human MRPs. The assay was validated by known MRP substrates, including calcein-AM (MRP1), vinblastine (MRP2) and chloromethylfluorescein diacetate (CMFDA; MRP5). The directional transport determined with these drugs in MRP-transfected cell lines could be blocked with the MRP inhibitor MK571. However, in contrast to transport of known MRP substrates, none of the common AEDs (carbamazepine, valproate, levetiracetam, phenytoin, lamotrigine and phenobarbital) used in this study was transported by MRP1, MRP2 or MRP5. A basolateral-to-apical transport of valproate, which could be inhibited by MK571 and probenecid, was determined in LLC cells (both wildtype and transfected), but the specific transporter involved was not identified. The data indicate that common AEDs are not substrates for human MRP1, MRP2 or MRP5, at least in the in vitro models used in this study. PMID:20080116

  12. Chiral Platinum(II) Complexes Featuring Phosphine and Chloroquine Ligands as Cytotoxic and Monofunctional DNA-Binding Agents.

    PubMed

    Villarreal, Wilmer; Colina-Vegas, Legna; Rodrigues de Oliveira, Clayton; Tenorio, Juan C; Ellena, Javier; Gozzo, Fábio C; Cominetti, Marcia Regina; Ferreira, Antonio G; Ferreira, Marco Antonio Barbosa; Navarro, Maribel; Batista, Alzir A

    2015-12-21

    Chiral molecules in nature are involved in many biological events; their selectivity and specificity make them of great interest for understanding the behavior of bioactive molecules, by providing information about the chiral discrimination. Inspired by these conformational properties, we present the design and synthesis of novel chiral platinum(II) complexes featuring phosphine and chloroquine ligands with the general formula [PtCl(P)2(CQ)]PF6 (where (P)2 = triphenylphosphine (PPh3) (5), 1,3-bis(diphenylphosphine)propane (dppp) (6), 1,4-bis(diphenylphosphine)butane (dppb) (7), 1,1'-bis(diphenylphosphine)ferrocene (dppf) (8), and CQ = chloroquine] and their precursors of the type [PtCl2(P)2] are described. The complexes were characterized by elemental analysis, absorption spectroscopy in the infrared and ultraviolet-visible (UV-vis) regions, multinuclear ((1)H, (13)C, (31)P, (15)N, and (195)Pt) NMR spectroscopy, cyclic voltammetry, and mass spectrometry (in the case of chloroquine complexes). The interactions of the new platinum-chloroquine complexes with both albumin (BSA), using fluorescence spectroscopy, and DNA, by four widely reported methods were also evaluated. These experiments showed that these Pt-CQ complexes interact strongly with DNA and have high affinities for BSA, in contrast to CQ and CQDP (chloroquine diphosphate), which interact weakly with these biomolecules. Additional assays were performed in order to investigate the cytotoxicity of the platinum complexes against two healthy cell lines (mouse fibroblasts (L929) and the Chinese hamster lung (V79-4)) and four tumor cell lines (human breast (MDA-MB-231 and MCF-7), human lung (A549), and human prostate (DU-145)). The results suggest that the Pt-CQ complexes are generally more cytotoxic than the free CQ, showing that they are promising as anticancer drugs. PMID:26606142

  13. The linker region of breast cancer resistance protein ABCG2 is critical for coupling of ATP-dependent drug transport.

    PubMed

    Macalou, S; Robey, R W; Jabor Gozzi, G; Shukla, S; Grosjean, I; Hegedus, T; Ambudkar, S V; Bates, S E; Di Pietro, A

    2016-05-01

    The ATP-binding cassette (ABC) transporters of class G display a different domain organisation than P-glycoprotein/ABCB1 and bacterial homologues with a nucleotide-binding domain preceding the transmembrane domain. The linker region connecting these domains is unique and its function and structure cannot be predicted. Sequence analysis revealed that the human ABCG2 linker contains a LSGGE sequence, homologous to the canonical C-motif/ABC signature present in all ABC nucleotide-binding domains. Predictions of disorder and of secondary structures indicated that this C2-sequence was highly mobile and located between an α-helix and a loop similarly to the C-motif. Point mutations of the two first residues of the C2-sequence fully abolished the transport-coupled ATPase activity, and led to the complete loss of cell resistance to mitoxantrone. The interaction with potent, selective and non-competitive, ABCG2 inhibitors was also significantly altered upon mutation. These results suggest an important mechanistic role for the C2-sequence of the ABCG2 linker region in ATP binding and/or hydrolysis coupled to drug efflux. PMID:26708291

  14. Bafetinib (INNO-406) reverses multidrug resistance by inhibiting the efflux function of ABCB1 and ABCG2 transporters.

    PubMed

    Zhang, Yun-Kai; Zhang, Guan-Nan; Wang, Yi-Jun; Patel, Bhargav A; Talele, Tanaji T; Yang, Dong-Hua; Chen, Zhe-Sheng

    2016-01-01

    ATP-Binding Cassette transporters are involved in the efflux of xenobiotic compounds and are responsible for decreasing drug accumulation in multidrug resistant (MDR) cells. Discovered by structure-based virtual screening algorithms, bafetinib, a Bcr-Abl/Lyn tyrosine kinase inhibitor, was found to have inhibitory effects on both ABCB1- and ABCG2-mediated MDR in this in-vitro investigation. Bafetinib significantly sensitized ABCB1 and ABCG2 overexpressing MDR cells to their anticancer substrates and increased the intracellular accumulation of anticancer drugs, particularly doxorubicin and [(3)H]-paclitaxel in ABCB1 overexpressing cells; mitoxantrone and [(3)H]-mitoxantrone in ABCG2 overexpressing cells, respectively. Bafetinib stimulated ABCB1 ATPase activities while inhibited ABCG2 ATPase activities. There were no significant changes in the expression level or the subcellular distribution of ABCB1 and ABCG2 in the cells exposed to 3 μM of bafetinib. Overall, our study indicated that bafetinib reversed ABCB1- and ABCG2-mediated MDR by blocking the drug efflux function of these transporters. These findings might be useful in developing combination therapy for MDR cancer treatment. PMID:27157787

  15. Effect of heat treatment of digestion-resistant fraction from soybean on retarding of bile acid transport in vitro

    PubMed Central

    Han, Sung-Hee; Lee, Seog-Won

    2009-01-01

    In this study, we investigated the heat effect of digestion-resistant fraction (RF) from soybean on retarding bile acid transport in vitro. The RFs from soybean retarded bile acid transport. A raw, unheated RF of soybean (RRF-SOY) was significantly more effective than the heated RF of soybean (HRF-SOY). The RS1 which physically trapped in milled grains and inaccessible to digestive enzyme after 18 hrs incubation level of content in RRF-SOY was found to be as high as 24.1% and after heating the RS1 of HRF-SOY was significantly reduced to 16.8%. The X-ray diffraction pattern of RF from soybean was altered after heat treatment. The RFs from soybean were characterized by peak at diffraction angles of 12.0° and 20.0° corresponding to RS content. Cellulose contents of RRF-SOY was 5% higher than that of HRF-SOY and pentosan contents of RRF-SOY was 5% higher than that of HRF-SOY, too. Whereas the hemicellulose content of RRF-SOY was 13% lower than HRF-SOY.

  16. Bafetinib (INNO-406) reverses multidrug resistance by inhibiting the efflux function of ABCB1 and ABCG2 transporters

    PubMed Central

    Zhang, Yun-Kai; Zhang, Guan-Nan; Wang, Yi-Jun; Patel, Bhargav A.; Talele, Tanaji T.; Yang, Dong-Hua; Chen, Zhe-Sheng

    2016-01-01

    ATP-Binding Cassette transporters are involved in the efflux of xenobiotic compounds and are responsible for decreasing drug accumulation in multidrug resistant (MDR) cells. Discovered by structure-based virtual screening algorithms, bafetinib, a Bcr-Abl/Lyn tyrosine kinase inhibitor, was found to have inhibitory effects on both ABCB1- and ABCG2-mediated MDR in this in-vitro investigation. Bafetinib significantly sensitized ABCB1 and ABCG2 overexpressing MDR cells to their anticancer substrates and increased the intracellular accumulation of anticancer drugs, particularly doxorubicin and [3H]-paclitaxel in ABCB1 overexpressing cells; mitoxantrone and [3H]-mitoxantrone in ABCG2 overexpressing cells, respectively. Bafetinib stimulated ABCB1 ATPase activities while inhibited ABCG2 ATPase activities. There were no significant changes in the expression level or the subcellular distribution of ABCB1 and ABCG2 in the cells exposed to 3 μM of bafetinib. Overall, our study indicated that bafetinib reversed ABCB1- and ABCG2-mediated MDR by blocking the drug efflux function of these transporters. These findings might be useful in developing combination therapy for MDR cancer treatment. PMID:27157787

  17. Novel ABC Transporter Gene, vga(C), Located on a Multiresistance Plasmid from a Porcine Methicillin-Resistant Staphylococcus aureus ST398 Strain ▿

    PubMed Central

    Kadlec, Kristina; Schwarz, Stefan

    2009-01-01

    A novel ABC transporter gene, vga(C), was identified on the 14,365-bp multiresistance plasmid pKKS825 in a porcine methicillin (meticillin)-resistant Staphylococcus aureus isolate of sequence type 398. The vga(C) gene encodes a 523-amino-acid protein which confers resistance not only to streptogramin A antibiotics but also to lincosamides and pleuromutilins. Plasmid pKKS825 also carries the resistance genes aadD, tet(L), and dfrK, which may enable the coselection of vga(C) under selective pressure by kanamycin/neomycin, tetracyclines, and trimethoprim. PMID:19470508

  18. Heat resistant materials and their feasibility issues for a space nuclear transportation system

    SciTech Connect

    Olsen, C.S.

    1991-01-01

    A number of nuclear propulsion concepts based on solid-core nuclear propulsion are being evaluated for a nuclear propulsion transportation system to support the Space Exploration Initiative (SEI) involving the reestablishment of a manned lunar base and the subsequent exploration of Mars. These systems will require high-temperature materials to meet the operating conditions with appropriate reliability and safety built into these systems through the selection and testing of appropriate materials. The application of materials for nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) systems and the feasibility issues identified for their use will be discussed. Some mechanical property measurements have been obtained, and compatibility tests were conducted to help identify feasibility issues. 3 refs., 1 fig., 4 tabs.

  19. A transporter for abiotic stress and plant metabolite resistance in the ectomycorrhizal fungus Tricholoma vaccinum.

    PubMed

    Schlunk, Ines; Krause, Katrin; Wirth, Sophia; Kothe, Erika

    2015-12-01

    Fungi exposed to toxic substances including heavy metals, xenobiotics, or secondary metabolites formed by co-occurring plants or other microorganisms require a detoxification system provided by exporters of several classes of transmembrane proteins. In case of mycorrhiza, plant metabolites need to be exported at the plant interface, while the extraradical hyphae may prevent heavy metal uptake, thus acting as a biofilter to the host plant at high environmental concentrations. One major family of such transporter proteins is the multidrug and toxic compound extrusion (MATE) class, a member of which, Mte1, was studied in the ectomycorrhizal fungus Tricholoma vaccinum. Phylogenetic analyses placed the protein in a subgroup of basidiomycete MATE sequences. The gene mte1 was found to be induced during symbiotic interaction. It mediated detoxification of xenobiotics and metal ions such as Cu, Li, Al, and Ni, as well as secondary plant metabolites if heterologously expressed in Saccharomyces cerevisiae. PMID:25563836

  20. The enriched fraction of Elephantopus scaber Triggers apoptosis and inhibits multi-drug resistance transporters in human epithelial cancer cells

    PubMed Central

    Beeran, Asmy Appadath; Maliyakkal, Naseer; Rao, Chamallamudi Mallikarjuna; Udupa, Nayanabhirama

    2015-01-01

    Background: Medicinal plants have played an important role in the development of clinically useful anticancer agents. Elephantopus scaber (Asteraceae) (ES) is widely used in Indian traditional system of medicine for the treatment of various ailments including cancer. Objective: To investigate anticancer effects of ES in human epithelial cancer cells. Materials and Methods: Cytotoxicity of ethanolic extract of ES (ES-ET) and its fractions, such as ES Petroleum ether fraction (ES-PET), ES Dichloromethane fraction (ES DCM), n Butyl alcohol fraction (ES-BT), and ES-Rest (ES-R) were assessed in human epithelial cancer cell lines using sulforhodamine B (SRB) assay. Acridine orange/ethidium bromide assay and Hoechst 33342 assays were used to gauge induction of apoptosis. Cell cycle analysis and micronuclei assay were used to assess cell cycle specific pharmacological effects and drug induced genotoxicty. Further, the ability of ES to inhibit multi drug resistant (MDR) transporters (ABC-B1 and ABC-G2) was determined by Rhodamine (Rho) and Mitoxantrone (MXR) efflux assays. Results: The enriched fraction of ES (ES DCM) possessed dose-dependent potent cytotoxicity in human epithelial cancer cells. Further, treatment of cancer cells (HeLa, A549, MCF-7, and Caco-2) with ES DCM showed hall mark properties of apoptosis (membrane blebbing, nuclear condensation etc.). Similarly, ES DCM caused enhanced sub G0 content and micronuclei formation indicating the induction of apoptosis and drug induced genotoxicity in cancer cells, respectively. Interestingly, ES DCM inhibited MDR transporters (ABC B1 and ABC G2) in cancer cells. Conclusion: The enriched fraction of ES imparted cytotoxic effects, triggered apoptosis, induced genotoxicity, and inhibited MDR transporters in human epithelial cancer cells. Thus, ES appears to be potential anticancer agent. PMID:25829763

  1. MFS transporters required for multidrug/multixenobiotic (MD/MX) resistance in the model yeast: understanding their physiological function through post-genomic approaches

    PubMed Central

    dos Santos, Sandra C.; Teixeira, Miguel C.; Dias, Paulo J.; Sá-Correia, Isabel

    2014-01-01

    Multidrug/Multixenobiotic resistance (MDR/MXR) is a widespread phenomenon with clinical, agricultural and biotechnological implications, where MDR/MXR transporters that are presumably able to catalyze the efflux of multiple cytotoxic compounds play a key role in the acquisition of resistance. However, although these proteins have been traditionally considered drug exporters, the physiological function of MDR/MXR transporters and the exact mechanism of their involvement in resistance to cytotoxic compounds are still open to debate. In fact, the wide range of structurally and functionally unrelated substrates that these transporters are presumably able to export has puzzled researchers for years. The discussion has now shifted toward the possibility of at least some MDR/MXR transporters exerting their effect as the result of a natural physiological role in the cell, rather than through the direct export of cytotoxic compounds, while the hypothesis that MDR/MXR transporters may have evolved in nature for other purposes than conferring chemoprotection has been gaining momentum in recent years. This review focuses on the drug transporters of the Major Facilitator Superfamily (MFS; drug:H+ antiporters) in the model yeast Saccharomyces cerevisiae. New insights into the natural roles of these transporters are described and discussed, focusing on the knowledge obtained or suggested by post-genomic research. The new information reviewed here provides clues into the unexpectedly complex roles of these transporters, including a proposed indirect regulation of the stress response machinery and control of membrane potential and/or internal pH, with a special emphasis on a genome-wide view of the regulation and evolution of MDR/MXR-MFS transporters. PMID:24847282

  2. Inhibition of Autophagy by Chloroquine Enhances the Antitumor Efficacy of Sorafenib in Glioblastoma.

    PubMed

    Liu, Xiangyu; Sun, Kangjian; Wang, Handong; Dai, Yuyuan

    2016-10-01

    Glioblastoma multiforme (GBM) is the most aggressive and common brain tumor in adults. Sorafenib, a multi-kinase inhibitor, has been shown to inhibit cell proliferation and induce apoptosis through inhibition of STAT3 signaling in glioblastoma cells and in intracranial gliomas. However, sorafenib also induces cell autophagy. Due to the dual roles of autophagy in tumor cell survival and death, the therapeutic effect of sorafenib on glioblastoma is uncertain. Here, we combined sorafenib treatment in GBM cells (U373 and LN229) and tumors with the autophagy inhibitor chloroquine. We found that blockage of autophagy further inhibited cell proliferation and migration and induced cell apoptosis in vitro and in vivo. These findings suggest the possibility of combination treatment with sorafenib and autophagy inhibitors for GBM. PMID:26971793

  3. Chloroquine-induced bilateral anterior shoulder dislocation: a unique aetiology for a rare clinical problem.

    PubMed

    Martin, Alexander Nicholas; Tsekes, Dimitris; White, William James; Rossouw, Dan

    2016-01-01

    Bilateral anterior shoulder dislocation is a rare clinical entity with few case reports and limited series published in the literature. Bilateral shoulder dislocations are rare and of them, most are posterior. We present a highly unusual case of bilateral, atraumatic, anterior shoulder dislocation with concomitant comminuted greater tuberosity fracture on the right side, secondary to seizure, in a patient without known epilepsy, induced by oral chloroquine medication. We demonstrate the treatment approach that led to a satisfactory clinical outcome, evidenced by radiological union, clinical assessment and Patient Reported Outcome Measure data, following non-operative management of both shoulders. The unusual mechanism for anterior shoulder dislocation, the asymmetric dislocation pattern and peculiar precipitant for the causative seizure all provide interesting learning points from this case. PMID:27005796

  4. Transport phenomena in membranes for PEMFC applications: an analytical approach to the calculation of membrane resistance

    NASA Astrophysics Data System (ADS)

    De Francesco, M.; Arato, E.; Costa, P.

    The transport phenomena of mass and electrical charges play an important role in the proton exchange membrane utilised in fuel cell applications. The calculation of the membrane ion and water transfer is usually determined in two ways: one is a semi-empirical mode that can be experimentally set for any application and cannot be used in the prediction of the characteristics of new cells, and the other is a very complex mathematical approach that needs very long calculation times. In fact, the membrane mass transfer model can cause problems in the management of PEM stack models, by increasing calculation times and, above all, convergence problems. This work attempts to overcome this bottleneck using a novel approach. The validation of the new approach has been made by applying the model results to a PEM fuel cell model and by comparing the overall results to those in the literature. The resulting calculation time warranted the application of this model to a very complex stack simulation, resulting in good fit and reasonable computing times.

  5. 2,3,7,8-Tetrachlorodibenzo-p-dioxin induced cell-specific drug transporters with acquired cisplatin resistance in cisplatin sensitive cancer cells.

    PubMed

    Gotovdorj, Tuvshinjargal; Lee, Eunil; Lim, Yongchul; Cha, Eun Jeong; Kwon, Daeho; Hong, Eunyoung; Kim, YunJeong; Oh, Min-Yeong

    2014-09-01

    2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce drug transporter genes such as the ATP-binding cassette G member 2 (ABCG2), which contributes to multidrug resistance. We investigated the effect of TCDD pretreatment on drug transporters induction from cancer cells of various origins. Cell viabilities after treatment of cisplatin were measured to evaluate acquiring cisplatin resistance by TCDD. Acquring cisplatin resistance was found only in cisplatin senstivie cancer cells including gastric SNU601, colon LS180, brain CRT-MG and lymphoma Jurkat cells which showed a significant increase in cell viability after combined treatment with TCDD and cisplatin. High increase of ABCG2 gene expression was found in SNU601 and LS180 cells with a mild increase in the expression of the ABCC3, ABCC5,and SLC29A2 genes in SNU601 cells, and of major vault protein (MVP) in LS180 cells. The AhR inhibitor kaempferol suppressed the upregulation of ABCG2 expression and reversed the TCDD-induced increase in cell viability in LS180 cells. However, in CRT-MG cells, other transporter genes including ABCC1, ABCC5, ABCA3, ABCA2, ABCB4, ABCG1, and SLC29A1 were up-regulated. These findings suggested the acquiring cisplatin resistance by TCDD associated with cancer cell-type-specific induction of drug transporters. PMID:25246735

  6. A Sensory Complex Consisting of an ATP-binding Cassette Transporter and a Two-component Regulatory System Controls Bacitracin Resistance in Bacillus subtilis*

    PubMed Central

    Dintner, Sebastian; Heermann, Ralf; Fang, Chong; Jung, Kirsten; Gebhard, Susanne

    2014-01-01

    Resistance against antimicrobial peptides in many Firmicutes bacteria is mediated by detoxification systems that are composed of a two-component regulatory system (TCS) and an ATP-binding cassette (ABC) transporter. The histidine kinases of these systems depend entirely on the transporter for sensing of antimicrobial peptides, suggesting a novel mode of signal transduction where the transporter constitutes the actual sensor. The aim of this study was to investigate the molecular mechanisms of this unusual signaling pathway in more detail, using the bacitracin resistance system BceRS-BceAB of Bacillus subtilis as an example. To analyze the proposed communication between TCS and the ABC transporter, we characterized their interactions by bacterial two-hybrid analyses and could show that the permease BceB and the histidine kinase BceS interact directly. In vitro pulldown assays confirmed this interaction, which was found to be independent of bacitracin. Because it was unknown whether BceAB-type transporters could detect their substrate peptides directly or instead recognized the peptide-target complex in the cell envelope, we next analyzed substrate binding by the transport permease, BceB. Direct and specific binding of bacitracin by BceB was demonstrated by surface plasmon resonance spectroscopy. Finally, in vitro signal transduction assays indicated that complex formation with the transporter influenced the autophosphorylation activity of the histidine kinase. Taken together, our findings clearly show the existence of a sensory complex composed of TCS and ABC transporters and provide the first functional insights into the mechanisms of stimulus perception, signal transduction, and antimicrobial resistance employed by Bce-like detoxification systems. PMID:25118291

  7. Diabetes: insulin resistance and derangements in lipid metabolism. Cure through intervention in fat transport and storage.

    PubMed

    Raz, Itamar; Eldor, Roi; Cernea, Simona; Shafrir, Eleazar

    2005-01-01

    We present multiple findings on derangements in lipid metabolism in type 2 diabetes. The increase in the intracellular deposition of triglycerides (TG) in muscles, liver and pancreas in subjects prone to diabetes is well documented and demonstrated to attenuate glucose metabolism by interfering with insulin signaling and insulin secretion. The obesity often associated with type 2 diabetes is mainly central, resulting in the overload of abdominal adipocytes with TG and reducing fat depot capacity to protect other tissues from utilizing a large proportion of dietary fat. In contrast to subcutaneous adipocytes, the central adipocytes exhibit a high rate of basal lipolysis and are highly sensitive to fat mobilizing hormones, but respond poorly to lipolysis restraining insulin. The enlarged visceral adipocytes are flooding the portal circulation with free fatty acids (FFA) at metabolically inappropriate time, when FFA should be oxidized, thus exposing nonadipose tissues to fat excess. This leads to ectopic TG accumulation in muscles, liver and pancreatic beta-cells, resulting in insulin resistance and beta-cell dysfunction. This situation, based on a large number of observations in humans and experimental animals, confirms that peripheral adipose tissue is closely regulated, performing a vital role of buffering fluxes of FFA in the circulation. The central adipose tissues tend to upset this balance by releasing large amounts of FFA. To reduce the excessive fat outflow from the abdominal depots and prevent the ectopic fat deposition it is important to decrease the volume of central fat stores or increase the peripheral fat stores. One possibility is to downregulate the activity of lipoprotein lipase, which is overexpressed in abdominal relatively to subcutaneous fat stores. This can be achieved by gastrointestinal bypass or gastroplasty, which decrease dietary fat absorption, or by direct means that include surgical removal of mesenteric fat. Indirect treatment consists

  8. Randomized Dose-Ranging Controlled Trial of AQ-13, a Candidate Antimalarial, and Chloroquine in Healthy Volunteers

    PubMed Central

    Mzayek, Fawaz; Deng, Haiyan; Mather, Frances J; Wasilevich, Elizabeth C; Liu, Huayin; Hadi, Christiane M; Chansolme, David H; Murphy, Holly A; Melek, Bekir H; Tenaglia, Alan N; Mushatt, David M; Dreisbach, Albert W; Lertora, Juan J. L; Krogstad, Donald J

    2007-01-01

    Objectives: To determine: (1) the pharmacokinetics and safety of an investigational aminoquinoline active against multidrug–resistant malaria parasites (AQ-13), including its effects on the QT interval, and (2) whether it has pharmacokinetic and safety profiles similar to chloroquine (CQ) in humans. Design: Phase I double-blind, randomized controlled trials to compare AQ-13 and CQ in healthy volunteers. Randomizations were performed at each step after completion of the previous dose. Setting: Tulane–Louisiana State University–Charity Hospital General Clinical Research Center in New Orleans. Participants: 126 healthy adults 21–45 years of age. Interventions: 10, 100, 300, 600, and 1,500 mg oral doses of CQ base in comparison with equivalent doses of AQ-13. Outcome Measures: Clinical and laboratory adverse events (AEs), pharmacokinetic parameters, and QT prolongation. Results: No hematologic, hepatic, renal, or other organ toxicity was observed with AQ-13 or CQ at any dose tested. Headache, lightheadedness/dizziness, and gastrointestinal (GI) tract–related symptoms were the most common AEs. Although symptoms were more frequent with AQ-13, the numbers of volunteers who experienced symptoms with AQ-13 and CQ were similar (for AQ-13 and CQ, respectively: headache, 17/63 and 10/63, p = 0.2; lightheadedness/dizziness, 11/63 and 8/63, p = 0.6; GI symptoms, 14/63 and 13/63; p = 0.9). Both AQ-13 and CQ exhibited linear pharmacokinetics. However, AQ-13 was cleared more rapidly than CQ (respectively, median oral clearance 14.0–14.7 l/h versus 9.5–11.3 l/h; p ≤ 0.03). QTc prolongation was greater with CQ than AQ-13 (CQ: mean increase of 28 ms; 95% confidence interval [CI], 18 to 38 ms, versus AQ-13: mean increase of 10 ms; 95% CI, 2 to 17 ms; p = 0.01). There were no arrhythmias or other cardiac AEs with either AQ-13 or CQ. Conclusions: These studies revealed minimal differences in toxicity between AQ-13 and CQ, and similar linear pharmacokinetics. PMID:17213921

  9. Age- and sex-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters.

    PubMed

    Kang, Seok Kyu; Markowitz, Geoffrey J; Kim, Shin Tae; Johnston, Michael V; Kadam, Shilpa D

    2015-01-01

    Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB), with NKCC1 antagonist bumetanide (BTN) as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in post-natal day 7, 10, and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs) quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy. PMID:26029047

  10. Age- and sex-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters

    PubMed Central

    Kang, Seok Kyu; Markowitz, Geoffrey J.; Kim, Shin Tae; Johnston, Michael V.; Kadam, Shilpa D.

    2015-01-01

    Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB), with NKCC1 antagonist bumetanide (BTN) as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in post-natal day 7, 10, and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs) quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy. PMID:26029047

  11. Comparison of the Transport of Tetracycline-Resistant and Tetracycline-Susceptible Escherichia coli Isolated from Lake Michigan.

    PubMed

    Walczak, Jacob J; Bardy, Sonia L; Feriancikova, Lucia; Xu, Shangping

    2011-11-01

    It was recently reported that tetracycline could enhance the mobility of manure-derived Escherichia coli within saturated porous media (Walczak et al. (Water Research 45:1681-1690, 2011)). It was also shown, however, that E. coli from various sources could display marked variation in their mobility (Bolster et al. (Journal of Environmental Quality 35:1018-1025, 2009)). The focus of this research was to examine if the observed difference in the mobility of manure-derived tetracycline-resistant (tet(R)) and tetracycline-susceptible (tet(S)) E. coli strains was source-dependent. Specifically, E. coli were isolated from Lake Michigan, and the influence of tetracycline resistance on Lake Michigan-derived E. coli was investigated through column transport experiments. Additionally, a variety of cell morphology and surface properties were determined and related to the observed bacterial transport behavior. Our experimental results showed that, consistent with previous observations, the deposition rate coefficients of the tet(R)E. coli strain was ~20-100% higher than those of the tet(S)E. coli strain. The zeta potential of the tet(R)E. coli cells was ~25 mV more negative than the tet(S)E. coli cells. Because the surfaces of the E. coli cells and the quartz sands were negatively charged, the repulsive electrostatic double-layer interaction between the tet(R)E. coli cells and the quartz sands was stronger, and the mobility of the tet(R)E. coli cells in the sand packs was thus higher. The tet(R)E. coli cells were also more hydrophilic than the tet(S)E. coli cells. Results from migration to hydrocarbon phase (MATH) tests showed that about ~35% more tet(S)E. coli cells partitioned to the hydrocarbon phase. As it was previously shown that cell hydrophobicity could enhance the attachment of bacterial cells to quartz sand, the difference in cell hydrophobicity could also have contributed to the observed higher mobility of the tet(R)E. coli cells. The size of the tet(R) and tet

  12. Evidence for dual mode of action of a thiosemicarbazone, NSC73306: A potent substrate of the multidrug resistance-linked ABCG2 transporter

    PubMed Central

    Wu, Chung-Pu; Shukla, Suneet; Calcagno, Anna Maria; Hall, Matthew D.; Gottesman, Michael M.; Ambudkar, Suresh V.

    2008-01-01

    Multidrug resistance due to reduced drug accumulation is a phenomenon predominantly caused by the overexpression of members of the ATP-binding cassette transporters, including ABCB1 (P-glycoprotein), ABCG2 and several ABCC family members (MRPs). We previously reported that a thiosemicarbazone derivative, NSC73306, is cytotoxic to carcinoma cells that overexpress functional P-glycoprotein and it re-sensitizes these cells to chemotherapeutics. In this study, we investigated the effect of NSC73306 on cells overexpressing other ABC drug transporters, including ABCG2, MRP1, MRP4 and MRP5. Our findings demonstrated that NSC73306 is not more toxic to cells that overexpress these transporters compared to their respective parental cells, and these transporters do not confer resistance to NSC73306 either. In spite of this, we observed that NSC73306 is a transport substrate for ABCG2 that can effectively inhibit ABCG2-mediated drug transport and reverse resistance to both mitoxantrone and topotecan in ABCG2-expressing cells. Interactions between NSC73306 and the ABCG2 drug-binding site(s) were confirmed by its stimulatory effect on ATPase activity (140–150 nM concentration required for 50% stimulation) and by inhibition of [125I]-Iodoarylazidoprazosin photolabeling (50% inhibition at 250–400 nM) of the substrate-binding site(s). Overall, NSC73306 appears to be a potent modulator of ABCG2 that does not interact with MRP1, MRP4 or MRP5. Collectively, these data suggest that NSC73306 can potentially be used, due to its dual mode of action, as an effective agent to overcome drug resistance by eliminating P-glycoprotein-overexpressing cells, and by acting as a potent modulator that re-sensitizes ABCG2-expressing cancer cells to chemotherapeutics. PMID:18089722

  13. The effect of chloroquine prophylaxis on yellow fever vaccine antibody response: comparison of plaque reduction neutralization test and enzyme-linked immunosorbent assay.

    PubMed

    Barry, M; Patterson, J E; Tirrell, S; Cullen, M R; Shope, R E

    1991-01-01

    Weekly oral chloroquine prophylaxis for malaria has been associated with impaired antibody response to intradermal rabies vaccination. Experimental data indicate that chloroquine may inhibit yellow fever virus in vitro, yet there has been no clinical evidence to suggest that antibody response to yellow fever vaccine is impaired by concomitant oral administration of chloroquine. A prospective trial was undertaken to evaluate the antibody response to yellow fever 17D vaccine (Connaught Laboratories) of volunteers who were randomized to taking either chloroquine or no drug. Of fifty subjects, 28 were randomized to taking chloroquine, 22 were randomized to taking no drug. Yellow fever 17D vaccine was administered on day 0 and blood sampled on days 0, 14, 35 and 210. Chloroquine was administered weekly for four weeks. There was no significant difference in peak antibody titer by plaque reduction neutralization testing (PRNT) between the group that took chloroquine (mean log peak of reciprocal titer 1.43 +/- SD 0.60) with vaccine subcutaneously compared to vaccine-only group (mean log peak of reciprocal titer = 1.21 +/- 0.55). All fifty subjects seroconverted to yellow fever vaccine by day 210. ELISA testing was also performed on all subjects. The two tests showed good correlation (Spearman r = 0.675), although ELISA readings were positive by day 14 in significantly more subjects (p = .01). We conclude that routine anti-malarial doses of chloroquine do not affect antibody response to yellow fever 17D vaccine. ELISA testing, a less complex and less time-consuming test, correlates well with PRNT and is proposed for additional trials to measure yellow fever 17D vaccine response in flavivirus non-immune subjects. PMID:1996743

  14. Therapeutic Assessment of Chloroquine-Primaquine Combined Regimen in Adult Cohort of Plasmodium vivax Malaria from Primary Care Centres in Southwestern India

    PubMed Central

    Saravu, Kavitha; Kumar, Rishikesh; Ashok, Herikudru; Kundapura, Premananda; Kamath, Veena; Kamath, Asha; Mukhopadhyay, Chiranjay

    2016-01-01

    Background Several reports of chloroquine treatment failure and resistance in Plasmodium vivax malaria from Southeast Asian countries have been published. Present study was undertaken to assess the efficacy of chloroquine-primaquine (CQ-PQ) combined regimen for the treatment of P. vivax malaria patients who were catered by the selected primary health centres (PHCs) of Udupi taluk, Udupi district, Karnataka, India. Method Five PHCs were selected within Udupi taluk based on probability proportional to size. In-vivo therapeutic efficacy assessment of CQ (1500 mg over three days) plus PQ (210 mg over 14 days) regimen was carried out in accordance with the World Health Organization’s protocol of 28 days follow-up among microscopically diagnosed monoinfection P. vivax cohort. Results In total, 161 participants were recruited in the study of which, 155 (96.3%) participants completed till day 28 follow-up, fully complied with the treatment regimen and showed adequate clinical and parasitological response. Loss to follow up was noted with 5 (3.1%) participants and non-compliance with treatment regimen occurred with one participant (0.6%). Glucose-6-phosphate dehydrogenase deficiency (G6PDd, <30% of normal mean activity) was noted among 5 (3.1%) participants and one of them did develop PQ induced dark-brown urination which subsided after PQ discontinuation. G6PDd patients were treated with PQ 45 mg/week for eight weeks while PQ was discontinued in one case with G6PD 1.4 U/g Hb due to complaint of reddish-brown coloured urine by 48 hours of PQ initiation. Nested polymerase chain reaction test revealed 45 (28%) cases as mixed (vivax and falciparum) malaria. Conclusions The CQ-PQ combined regimen remains outstandingly effective to treat uncomplicated P. vivax malaria in Udupi taluk and thus it should continue as first line regimen. For all P. vivax cases, G6PD screening before PQ administration must be mandatory and made available in all PHCs. PMID:27315280

  15. Cysteinyl Leukotriene Receptor 1/2 Antagonists Nonselectively Modulate Organic Anion Transport by Multidrug Resistance Proteins (MRP1-4).

    PubMed

    Csandl, Mark A; Conseil, Gwenaëlle; Cole, Susan P C

    2016-06-01

    Active efflux of both drugs and organic anion metabolites is mediated by the multidrug resistance proteins (MRPs). MRP1 (ABCC1), MRP2 (ABCC2), MRP3 (ABCC3), and MRP4 (ABCC4) have partially overlapping substrate specificities and all transport 17β-estradiol 17-(β-d-glucuronide) (E217βG). The cysteinyl leukotriene receptor 1 (CysLT1R) antagonist MK-571 inhibits all four MRP homologs, but little is known about the modulatory effects of newer leukotriene modifiers (LTMs). Here we examined the effects of seven CysLT1R- and CysLT2R-selective LTMs on E217βG uptake into MRP1-4-enriched inside-out membrane vesicles. Their effects on uptake of an additional physiologic solute were also measured for MRP1 [leukotriene C4 (LTC4)] and MRP4 [prostaglandin E2 (PGE2)]. The two CysLT2R-selective LTMs studied were generally more potent inhibitors than CysLT1R-selective LTMs, but neither class of antagonists showed any MRP selectivity. For E217βG uptake, LTM IC50s ranged from 1.2 to 26.9 μM and were most comparable for MRP1 and MRP4. The LTM rank order inhibitory potencies for E217βG versus LTC4 uptake by MRP1, and E217βG versus PGE2 uptake by MRP4, were also similar. Three of four CysLT1R-selective LTMs also stimulated MRP2 (but not MRP3) transport and thus exerted a concentration-dependent biphasic effect on MRP2. The fourth CysLT1R antagonist, LY171883, only stimulated MRP2 (and MRP3) transport but none of the MRPs were stimulated by either CysLT2R-selective LTM. We conclude that, in contrast to their CysLTR selectivity, CysLTR antagonists show no MRP homolog selectivity, and data should be interpreted cautiously if obtained from LTMs in systems in which more than one MRP is present. PMID:27068271

  16. Differences in cadmium transport to the testis, epididymis, and brain in cadmium-sensitive and -resistant murine strains 129/J and A/J.

    PubMed

    King, L M; Banks, W A; George, W J

    1999-05-01

    Although most animals with scrotal testes are susceptible to cadmium-induced testicular toxicity, strain-related differences are seen in mice. Resistant murine strains demonstrate a decreased cadmium concentration in the testis and also in the epididymis and seminal vesicle. In this study we analyzed cadmium transport into tissues with a vascular barrier, the testis, epididymis, and brain, in an attempt to characterize the mechanisms of strain resistance to cadmium-induced testicular toxicity. In the resistant murine strain A/J, 109Cd transport (administered as 109CdCl2) was significantly attenuated in the testis, epididymis, and brain, when compared to the sensitive murine strain 129/J. The unidirectional influx constant (Ki, in microliter g-1 min-1) for 109Cd was 0.01929 in the A/J testis as compared with 1.174 in the 129/J testis (P <.0001). The percentage of a 109Cd dose that reached the A/J testis by 60 min was over 10 times less than that which reached the 129/J testis. The transport system used by cadmium in the 129/J testis was saturable, with 20 microM unlabeled cadmium chloride inhibiting transport by over 60%. The transporter was competitively inhibited by zinc (P =. 00017), but not by calcium, indicating a specificity in ion transport. Studies with isolated tubules and analysis of testicular fluid compartments demonstrated no significant difference in cadmium uptake or efflux between the strains when corrected for the amount of 109Cd entering the testis. Therefore, murine strain differences in testicular sensitivity to cadmium appear to be related to the variable presence of a transport system for cadmium in the testicular vasculature. PMID:10215659

  17. The sRNA SorY confers resistance during photooxidative stress by affecting a metabolite transporter in Rhodobacter sphaeroides

    PubMed Central

    Adnan, Fazal; Weber, Lennart; Klug, Gabriele

    2015-01-01

    Exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen (1O2) in the facultative photosynthetic bacterium Rhodobacter sphaeroides. We have identified SorY as an sRNA, which is induced under several stress conditions and confers increased resistance against 1O2. SorY by direct interaction affects the takP mRNA, encoding a TRAP-T transporter. We present a model in which SorY reduces the metabolite flux into the tricarboxylic acid cycle (TCA cycle) by reducing malate import through TakP. It was previously shown that oxidative stress in bacteria leads to switch from glycolysis to the pentose phosphate pathway and to reduced activity of the TCA cycle. As a consequence the production of the prooxidant NADH is reduced and production of the protective NADPH is enhanced. In R. sphaeroides enzymes for glycolysis, pentose phosphate pathway, Entner–Doudoroff pathway and gluconeogenesis are induced in response to 1O2 by the alternative sigma factor RpoHII. The same is true for the sRNA SorY. By limiting malate import SorY thus contributes to the balance of the metabolic fluxes under photooxidative stress conditions. This assigns a so far unknown function to an sRNA in oxidative stress response. PMID:25833751

  18. History, Dynamics, and Public Health Importance of Malaria Parasite Resistance

    PubMed Central

    Talisuna, Ambrose O.; Bloland, Peter; D’Alessandro, Umberto

    2004-01-01

    Despite considerable efforts, malaria is still one of the most devastating infectious diseases in the tropics. The rapid spread of antimalarial drug resistance currently compounds this grim picture. In this paper, we review the history of antimalarial drug resistance and the methods for monitoring it and assess the current magnitude and burden of parasite resistance to two commonly used drugs: chloroquine and sulfadoxine-pyrimethamine. Furthermore, we review the factors involved in the emergence and spread of drug resistance and highlight its public health importance. Finally, we discuss ways of dealing with such a problem by using combination therapy and suggest some of the research themes needing urgent answers. PMID:14726463

  19. Oxygen transport resistance at gas diffusion layer - Air channel interfa