scholarly journals In VitroSensitivities of Plasmodium falciparum Isolates from the China-Myanmar Border to Piperaquine and Association with Polymorphisms in Candidate Genes

2013 ◽  
Vol 57 (4) ◽  
pp. 1723-1729 ◽  
Author(s):  
Mingming Hao ◽  
Dandan Jia ◽  
Qing Li ◽  
Yongshu He ◽  
Lili Yuan ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Mechanisms ◽  
Inhibitory Concentration ◽  
Pearson Correlation ◽  
Geometric Mean ◽  
Content Type ◽  
Artemisinin Derivatives ◽  
Wide Range ◽  
High Prevalence

ABSTRACTThe recent reports of resistance inPlasmodium falciparumto artemisinin derivatives and their partner drugs demand intensive studies toward understanding the molecular mechanisms of resistance. In this study, we examined thein vitrosusceptibility of 63P. falciparumfield isolates collected from the China-Myanmar border area to chloroquine (CQ) and piperaquine (PPQ). Parasite isolates remained highly resistant to CQ, with the geometric mean 50% inhibitory concentration (IC50) of 252.7 nM and a range of 51.9 to 1,052.0 nM. In comparison, these parasites had a geometric mean IC50of 28.4 nM for PPQ, with a fairly wide range of 5.3 to 132.0 nM, suggesting that certain parasite isolates displayed relatively high levels of resistance to PPQ. Interestingly, within the 4 years of study, the parasites exhibited a continuous decline in susceptibilities to both CQ and PPQ, and there was a significant correlation between responses to CQ and PPQ (Pearson correlation coefficient = 0.79,P< 0.0001). Consistent with the CQ-resistant phenotype, all parasites carried thepfcrtK76T mutation, and most parasites had the CVIET type that is prevalent in Southeast Asia. In contrast,pfmdr1mutations were relatively rare, and no gene amplification was detected. Only thepfmdr1N1042D mutation was associated with resistance to CQ. For thepfmrp1gene, four substitutions reached relatively high prevalence of >22%, and the I876V mutation was associated with reduced sensitivity to CQ. However, we could not establish a link between PPQ responses and the polymorphisms in the three genes associated with quinoline drug resistance.

scholarly journals In Vitro Antifungal Combination of Flucytosine with Amphotericin B, Voriconazole, or Micafungin against Candida auris Shows No Antagonism

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
A. L. Bidaud ◽  
F. Botterel ◽  
A. Chowdhary ◽  
E. Dannaoui
Keyword(s):  
Amphotericin B ◽  
Inhibitory Concentration ◽  
Geometric Mean ◽  
Multidrug Resistant ◽  
Candida Auris ◽  
Content Type ◽  
Hospital Acquired Infections ◽  
Resistant Mutants ◽  
Hospital Acquired

ABSTRACT Candida auris is an emerging, multidrug-resistant pathogen responsible for invasive hospital-acquired infections. Flucytosine is an effective anti-Candida species drug, but which cannot be used as a monotherapy because of the risk of development of resistant mutants during treatment. It is, therefore, noteworthy to test possible combinations with flucytosine that may have a synergistic interaction. In this study, we determined the in vitro interaction between flucytosine and amphotericin B, micafungin, or voriconazole. These combinations have been tested against 15 C. auris isolates. The MIC ranges (geometric mean [Gmean]) of flucytosine, amphotericin B, micafungin, and voriconazole were 0.125 to 1 μg/ml (0.42 μg/ml), 0.25 to 1 μg/ml (0.66 μg/ml), 0.125 to 0.5 μg/ml (0.3 μg/ml), and 0.03 to 4 μg/ml (1.05 μg/ml), respectively. When tested in combination, indifferent interactions were mostly observed with fractional inhibitory concentration index values from 0.5 to 1, 0.31 to 1.01, and 0.5 to 1.06 for the combinations of flucytosine with amphotericin B, micafungin, and voriconazole, respectively. A synergy was observed for the strain CBS 10913 from Japan. No antagonism was observed for any combination. The combination of flucytosine with amphotericin B or micafungin may be relevant for the treatment of C. auris infections.

scholarly journals Pleiotropic Biological Effects of Dietary Phenolic Compounds and their Metabolites on Energy Metabolism, Inflammation and Aging

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 596 ◽  
Author(s):  
María del Carmen Villegas-Aguilar ◽  
Álvaro Fernández-Ochoa ◽  
María de la Luz Cádiz-Gurrea ◽  
Sandra Pimentel-Moral ◽  
Jesús Lozano-Sánchez ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Phenolic Compounds ◽  
Molecular Mechanisms ◽  
Biological Effects ◽  
Biological Properties ◽  
In Vivo Studies ◽  
Wide Range ◽  
High Prevalence

Dietary phenolic compounds are considered as bioactive compounds that have effects in different chronic disorders related to oxidative stress, inflammation process, or aging. These compounds, coming from a wide range of natural sources, have shown a pleiotropic behavior on key proteins that act as regulators. In this sense, this review aims to compile information on the effect exerted by the phenolic compounds and their metabolites on the main metabolic pathways involved in energy metabolism, inflammatory response, aging and their relationship with the biological properties reported in high prevalence chronic diseases. Numerous in vitro and in vivo studies have demonstrated their pleiotropic molecular mechanisms of action and these findings raise the possibility that phenolic compounds have a wide variety of roles in different targets.

scholarly journals Plasmodium falciparum: In Vitro Cytotoxicity Testing Using MTT

1998 ◽  
Vol 3 (1) ◽  
pp. 49-53 ◽  
Author(s):  
J. Enrico Lazaro ◽  
Frederick Gay
Keyword(s):  
Plasmodium Falciparum ◽  
Culture System ◽  
Inhibitory Concentration ◽  
In Vitro Cytotoxicity ◽  
Mtt Method ◽  
Diphenyltetrazolium Bromide ◽  
Wide Range ◽  
In Vitro Culture System ◽  
Comparative Results

The microculture tetrazolium assay using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) was used to estimate the 50% inhibitory concentration of chloroquine, quinine, artemisinin, and atovaquone using a Plasmodium falciparum in vitro culture system. The MTT assay was compared to the standard tritiated hypoxan-thine assay and to a previously described method, the 2,2′-di-p-nitrophenyl-5,5′-diphenyl-3,3′-[3,3′-dimethoxy-4,4′-diphenylenel-ditetrazolium chloride (NBT) assay. In general, the results show that the three assays generate comparative results. The results of this study suggest that the MTT method is able to give a profile of cytotoxic dose response effects over a wide range of concentrations of a drug. The method may be used in work that does not require extreme pre-cision and sensitivity, for instance, as a portable rapid screen to assay natural products for in vitro cytotoxic ac-tivity against Plasmodium falciparum.

scholarly journals The Mu Subunit of Plasmodium falciparum Clathrin-Associated Adaptor Protein 2 ModulatesIn VitroParasite Response to Artemisinin and Quinine

2015 ◽  
Vol 59 (5) ◽  
pp. 2540-2547 ◽  
Author(s):  
Gisela Henriques ◽  
Donelly A. van Schalkwyk ◽  
Rebekah Burrow ◽  
David C. Warhurst ◽  
Eloise Thompson ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Adaptor Protein ◽  
Content Type ◽  
Artemisinin Derivatives ◽  
Combination Treatments ◽  
Antimalarial Resistance ◽  
Transgenic Parasites ◽  
Multiple Drugs

ABSTRACTThe emergence of drug-resistant parasites is a serious threat faced by malaria control programs. Understanding the genetic basis of resistance is critical to the success of treatment and intervention strategies. A novel locus associated with antimalarial resistance,ap2-mu(encoding the mu chain of the adaptor protein 2 [AP2] complex), was recently identified in studies on the rodent malaria parasitePlasmodium chabaudi(pcap2-mu). Furthermore, analysis in Kenyan malaria patients of polymorphisms in thePlasmodium falciparumap2-muhomologue,pfap2-mu, found evidence that differences in the amino acid encoded by codon 160 are associated with enhanced parasite survivalin vivofollowing combination treatments which included artemisinin derivatives. Here, we characterize the role ofpfap2-muin mediating thein vitroantimalarial drug response ofP. falciparumby generating transgenic parasites constitutively expressing codon 160 encoding either the wild-type Ser (Ser160) or the Asn mutant (160Asn) form ofpfap2-mu. Transgenic parasites carrying thepfap2-mu160Asn allele were significantly less sensitive to dihydroartemisinin using a standard 48-hin vitrotest, providing direct evidence of an altered parasite response to artemisinin. Our data also provide evidence thatpfap2-muvariants can modulate parasite sensitivity to quinine. No evidence was found thatpfap2-muvariants contribute to the slow-clearance phenotype exhibited byP. falciparumin Cambodian patients treated with artesunate monotherapy. These findings provide compelling evidence thatpfap2-mucan modulateP. falciparumresponses to multiple drugs. We propose that this gene should be evaluated further as a potential molecular marker of antimalarial resistance.

scholarly journals In Vitro Sensitivities of Plasmodium falciparum to Different Antimalarial Drugs in Uganda

2010 ◽  
Vol 54 (3) ◽  
pp. 1200-1206 ◽  
Author(s):  
Samuel L. Nsobya ◽  
Moses Kiggundu ◽  
Sarah Nanyunja ◽  
Moses Joloba ◽  
Bryan Greenhouse ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Inhibitory Concentration ◽  
Drug Efficacy ◽  
New Combination ◽  
Efficacy Trial ◽  
Wide Range ◽  
Highly Correlated ◽  
Multiple Drugs ◽  
Combination Regimens

ABSTRACT The control of malaria is challenged by resistance of Plasmodium falciparum to multiple drugs. New combination regimens are now advocated for the treatment of uncomplicated falciparum malaria, but the extent of resistance to newer agents is incompletely understood. We measured the in vitro sensitivity of P. falciparum parasites cultured from children enrolled in a drug efficacy trial in Kampala, Uganda, from 2006 to 2008. Sensitivities were measured by comparing levels of histidine-rich protein-2 in parasites incubated with different concentrations of drugs with those in untreated controls. The cultured parasites exhibited a wide range of sensitivities to chloroquine (CQ); monodesethylamodiaquine (MDAQ), the major active metabolite of amodiaquine; and quinine (QN). Mean 50% inhibitory concentration (IC50) results were above standard cutoffs for resistance for CQ and MDAQ. Parasites were generally sensitive to dihydroartemisinin (DHA), lumefantrine (LM), and piperaquine (PQ). For CQ, MDAQ, and QN but not the other drugs, activities against individual strains were highly correlated. We also assessed known resistance-mediating polymorphisms in two putative transporters, pfcrt and pfmdr1. When parasites that were least and most sensitive to each drug were compared, the pfmdr1 86Y mutation was significantly more common in parasites that were most resistant to CQ and MDAQ, and the pfmdr1 D1246Y mutation was significantly more common in parasites that were most resistant to MDAQ and QN. In summary, we demonstrated in parasites from Kampala a range of sensitivities to older drugs; correlation of sensitivities to CQ, MDAQ, and QN; and good activity against nearly all strains for DHA, LM, and PQ.

scholarly journals In VitroActivity of Proveblue (Methylene Blue) on Plasmodium falciparum Strains Resistant to Standard Antimalarial Drugs

2011 ◽  
Vol 55 (5) ◽  
pp. 2472-2474 ◽  
Author(s):  
Aurélie Pascual ◽  
Maud Henry ◽  
Sébastien Briolant ◽  
Serge Charras ◽  
Eric Baret ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Plasmodium Falciparum ◽  
Inhibitory Concentration ◽  
Geometric Mean ◽  
Antimalarial Drugs ◽  
European Pharmacopoeia ◽  
Content Type ◽  
Copy Numbers ◽  
Antimalarial Resistance

ABSTRACTThe geometric mean 50% inhibitory concentration (IC50) for Proveblue, a methylene blue complying with the European Pharmacopoeia, was more active on 23P. falciparumstrains than chloroquine, quinine, mefloquine, monodesethylamodiaquine, and lumefantrine. We did not find significant associations between the Proveblue IC50and polymorphisms in thepfcrt,pfmdr1,pfmdr2,pfmrp, andpfnhe-1genes or the copy numbers of thepfmdr1andpfmdr2genes, all of which are involved in antimalarial resistance.

scholarly journals Impact of Sickle Cell Trait Hemoglobin on the Intraerythrocytic Transcriptional Program of Plasmodium falciparum

mSphere ◽  
2021 ◽  
Author(s):  
Joseph W. Saelens ◽  
Jens E. V. Petersen ◽  
Elizabeth Freedman ◽  
Robert C. Moseley ◽  
Drissa Konaté ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Mechanisms ◽  
Sickle Cell Trait ◽  
Rna Seq ◽  
Transcriptional Program ◽  
Content Type ◽  
Life Threatening ◽  
The Impact

Sickle-trait hemoglobin (HbAS) confers nearly complete protection from severe, life-threatening malaria, yet the molecular mechanisms that underlie HbAS protection from severe malaria remain incompletely understood. Here, we used transcriptome sequencing (RNA-seq) to measure the impact of HbAS on the blood-stage transcriptome of Plasmodium falciparum in in vitro time series experiments and in vivo samples from natural infections.

scholarly journals Differential Association of Plasmodium falciparum Na+/H+Exchanger Polymorphism and Quinine Responses in Field- and Culture-Adapted Isolates of Plasmodium falciparum

2011 ◽  
Vol 55 (12) ◽  
pp. 5834-5841 ◽  
Author(s):  
Stéphane Pelleau ◽  
Lionel Bertaux ◽  
Sébastien Briolant ◽  
Michael T. Ferdig ◽  
Véronique Sinou ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Drug Testing ◽  
Inhibitory Concentration ◽  
Cumulative Effect ◽  
Differential Association ◽  
Microsatellite Sequence ◽  
Content Type ◽  
Field Isolates ◽  
Selection Of

ABSTRACTPlasmodium falciparumisolates with decreased susceptibility to quinine are increasingly being found in malaria patients. Mechanisms involved in this resistance are not yet understood. Several studies claim that alongside mutations in the Pfcrtand Pfmdr1genes, the Pfnhe-1Na+/H+exchanger polymorphism plays a role in decreasing susceptibility. However, conflicting results on the link between the Pfnhe-1gene and quinine resistance arise from field- and culture-adapted isolates. We tested the association between Pfnhe-1, Pfcrt, and Pfmdr1polymorphisms in field- and culture-adapted isolates from various countries with theirin vitrosusceptibility to quinine. Field isolates presented a higher diversity of the Pfnhe-1microsatellite sequence than culture-adapted isolates. In culture-adapted isolates but not in field isolates, mutations in the Pfcrtand Pfmdr1genes, as well as a higher number of DNNND repeats in the Pfnhe-1gene, were associated with a higher 50% inhibitory concentration (IC50) of quinine. Furthermore, most of the culture-adapted isolates with more than one DNNND repeat in the Pfnhe-1gene also harbored mutated Pfcrtand Pfmdr1genes with an apparent cumulative effect on quinine susceptibility. This study supports the involvement of the Pfnhe-1gene in the modulation of thein vitroquinine response when associated with mutated Pfcrtand Pfmdr1genes. Culture adaptation could be responsible for selection of specific haplotypes of these three genes. Methods used for drug testing might thus influence the association between Pfnhe-1polymorphism and quinine susceptibility. However, we do not exclude the possibility that in particular settings, Pfnhe-1polymorphism can be used as a molecular marker for surveillance of quinine resistance.

scholarly journals In Vitro Activities of Piperaquine and Other 4-Aminoquinolines against Clinical Isolates of Plasmodium falciparum in Cameroon

2003 ◽  
Vol 47 (4) ◽  
pp. 1391-1394 ◽  
Author(s):  
Leonardo K. Basco ◽  
Pascal Ringwald
Keyword(s):  
Plasmodium Falciparum ◽  
Inhibitory Concentration ◽  
Geometric Mean ◽  
Central Africa ◽  
New Drugs ◽  
Clinical Isolates ◽  
Highly Active ◽  
Synthetic Drug ◽  
Further Development

ABSTRACT The spread of chloroquine-resistant Plasmodium falciparum calls for a constant search for new drugs. The in vitro activity of piperaquine, a new Chinese synthetic drug belonging to the bisquinolines, was evaluated in 103 fresh clinical isolates of P. falciparum in Cameroon, Central Africa, and compared with that of other 4-aminoquinoline and Mannich base derivatives and dihydroartemisinin. Piperaquine was highly active (geometric mean 50% inhibitory concentration, 38.9 nmol/liter; range, 7.76 to 78.3 nmol/liter) and equally active (P > 0.05) against the chloroquine-sensitive and the chloroquine-resistant isolates. There was a significant but low correlation of response between chloroquine and piperaquine (r = 0.257, P < 0.05). These results suggest that further development of piperaquine, in combination with dihydroartemisinin, holds promise for use in chloroquine-resistant regions of endemicity.

scholarly journals Artemisinin-Resistant Plasmodium falciparum Parasites Exhibit Altered Patterns of Development in Infected Erythrocytes

2015 ◽  
Vol 59 (6) ◽  
pp. 3156-3167 ◽  
Author(s):  
Amanda Hott ◽  
Debora Casandra ◽  
Kansas N. Sparks ◽  
Lindsay C. Morton ◽  
Geocel-Grace Castanares ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Artemisinin Resistance ◽  
Drug Pressure ◽  
Content Type ◽  
Phenotypic Resistance ◽  
Artemisinin Derivatives ◽  
Stage Of Development ◽  
Clinical Resistance

ABSTRACTArtemisinin derivatives are used in combination with other antimalarial drugs for treatment of multidrug-resistant malaria worldwide. Clinical resistance to artemisinin recently emerged in southeast Asia, yetin vitrophenotypes for discerning mechanism(s) of resistance remain elusive. Here, we describe novel phenotypic resistance traits expressed by artemisinin-resistantPlasmodium falciparum. The resistant parasites exhibit altered patterns of development that result in reduced exposure to drug at the most susceptible stage of development in erythrocytes (trophozoites) and increased exposure in the most resistant stage (rings). In addition, a novelin vitrodelayed clearance assay (DCA) that assesses drug effects on asexual stages was found to correlate with parasite clearance half-lifein vivoas well as with mutations in the Kelch domain gene associated with resistance (Pf3D7_1343700). Importantly, all of the resistance phenotypes were stable in cloned parasites for more than 2 years without drug pressure. The results demonstrate artemisinin-resistantP. falciparumhas evolved a novel mechanism of phenotypic resistance to artemisinin drugs linked to abnormal cell cycle regulation. These results offer insights into a novel mechanism of drug resistance inP. falciparumand new tools for monitoring the spread of artemisinin resistance.

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