scholarly journals Role of Known Molecular Markers of Resistance in the Antimalarial Potency of Piperaquine and Dihydroartemisinin In Vitro

2009 ◽  
Vol 53 (4) ◽  
pp. 1362-1366 ◽  
Author(s):  
Sant Muangnoicharoen ◽  
David J. Johnson ◽  
Sornchai Looareesuwan ◽  
Srivicha Krudsood ◽  
Stephen A. Ward
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Artemisinin Combination Therapy ◽  
Parasite Line ◽  
South American ◽  
Resistance Markers ◽  
Positive Correlations ◽  
The Individual

ABSTRACT Using a range of laboratory-adapted and genetically modified Plasmodium falciparum parasite isolates, we investigated the interaction between dihydroartemisinin and piperaquine (PIP), the individual components of an artemisinin combination therapy currently under development, in addition to the role of known drug resistance genes in parasite susceptibility in vitro. All but one parasite line investigated displayed an interaction of dihydroartemisinin and PIP that was antagonistic, although the degree of antagonism was isolate dependent. In terms of resistance markers, the pfcrt haplotypes CVIET and SVMNT were positively associated with reduced sensitivity to PIP, with parasites carrying the South American CQR (SVMNT) allele being generally less sensitive than CVIET parasites. Parasites carrying the CQS (CVMNK) allele displayed a further increase in PIP sensitivity compared with CVIET and SVMNT parasites. Our data indicate that PIP sensitivity was not affected by pfmdr1 sequence status, despite positive correlations between the structurally related compound amodiaquine and pfmdr1 mutations in other studies. In contrast, neither the pfcrt nor pfmdr1 sequence status had any significant impact on susceptibility to dihydroartemisinin.

scholarly journals Culture-adapted Plasmodium falciparum isolates from UK travellers: in vitro drug sensitivity, clonality and drug resistance markers

2013 ◽  
Vol 12 (1) ◽  
pp. 320 ◽  
Author(s):  
Donelly A van Schalkwyk ◽  
Rebekah Burrow ◽  
Gisela Henriques ◽  
Nahla B Gadalla ◽  
Khalid B Beshir ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Drug Sensitivity ◽  
Resistance Markers

Evolution of Plasmodium falciparum drug resistance genes following artemisinin combination therapy in Sudan

2019 ◽  
Vol 113 (11) ◽  
pp. 693-700 ◽  
Author(s):  
Amani M A Bakhiet ◽  
Mohamed H Abdelraheem ◽  
Amani Kheir ◽  
Samia Omer ◽  
Linda Gismelseed ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Resistance Genes ◽  
Artemisinin Combination Therapy ◽  
National Guidelines ◽  
Treatment Practice ◽  
Health Authorities ◽  
Geographical Regions ◽  
High Prevalence ◽  
Resistance Markers

Abstract Background Malaria control efforts in Sudan rely heavily on case management. In 2004, health authorities adopted artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated malaria. However, some recent surveys have reported ACT failure and a prevalent irrational malaria treatment practice. Here we examine whether the widespread use of ACT and failure to adhere to national guidelines have led to the evolution of drug resistance genes. Methods We genotyped known drug resistance markers (Pfcrt, Pfmdr-1, Pfdhfr, Pfdhps, Pfk13 propeller) and their flanking microsatellites among Plasmodium falciparum isolates obtained between 2009 and 2016 in different geographical regions in Sudan. Data were then compared with published findings pre-ACT (1992–2003). Results A high prevalence of Pfcrt76T, Pfmdr-1-86Y, Pfdhfr51I, Pfdhfr108N, Pfdhps37G was observed in all regions, while no Pfk13 mutations were detected. Compared with pre-ACT data, Pfcrt-76T and Pfmdr-1-86Y have decayed, while Pfdhfr-51I, Pfdhfr-108N and Pfdhps-437G strengthened. Haplotypes Pfcrt-CVIET, Pfmdr-1-NFSND/YFSND, Pfdhfr-ICNI and Pfdhps-SGKAA predominated in all sites. Microsatellites flanking drug resistance genes showed lower diversity than neutral ones, signifying high ACT pressure/selection. Conclusions Evaluation of P. falciparum drug resistance genes in Sudan matches the drug deployment pattern. Regular monitoring of these genes, coupled with clinical response, should be considered to combat the spread of ACT resistance.

scholarly journals Assessment of the Drug Susceptibility of Plasmodium falciparum Clinical Isolates from Africa by Using a Plasmodium Lactate Dehydrogenase Immunodetection Assay and an Inhibitory Maximum Effect Model for Precise Measurement of the 50-Percent Inhibitory Concentration

2006 ◽  
Vol 50 (10) ◽  
pp. 3343-3349 ◽  
Author(s):  
Halima Kaddouri ◽  
Serge Nakache ◽  
Sandrine Houzé ◽  
France Mentré ◽  
Jacques Le Bras
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Lactate Dehydrogenase ◽  
Active Metabolite ◽  
Inhibitory Concentration ◽  
Drug Susceptibility ◽  
Maximum Effect ◽  
Malaria Parasites ◽  
Effect Model

ABSTRACT The extension of drug resistance among malaria-causing Plasmodium falciparum parasites in Africa necessitates implementation of new combined therapeutic strategies. Drug susceptibility phenotyping requires precise measurements. Until recently, schizont maturation and isotopic in vitro assays were the only methods available, but their use was limited by technical constraints. This explains the revived interest in the development of replacement methods, such as the Plasmodium lactate dehydrogenase (pLDH) immunodetection assay. We evaluated a commercially controlled pLDH enzyme-linked immunosorbent assay (ELISA; the ELISA-Malaria antigen test; DiaMed AG, Cressier s/Morat, Switzerland) to assess drug susceptibility in a standard in vitro assay using fairly basic laboratory equipment to study the in vitro resistance of malaria parasites to major antimalarials. Five Plasmodium falciparum clones and 121 clinical African isolates collected during 2003 and 2004 were studied by the pLDH ELISA and the [8-3H]hypoxanthine isotopic assay as a reference with four antimalarials. Nonlinear regression with a maximum effect model was used to estimate the 50% inhibitory concentration (IC50) and its confidence intervals. The two methods were observed to have similar reproducibilities, but the pLDH ELISA demonstrated a higher sensitivity. The high correlation (r = 0.98) and the high phenotypic agreement (κ = 0.88) between the two methods allowed comparison by determination of the IC50s. Recently collected Plasmodium falciparum African isolates were tested by pLDH ELISA and showed drug resistance or decreased susceptibilities of 62% to chloroquine and 11.5% to the active metabolite of amodiaquine. No decreased susceptibility to lumefantrine or the active metabolite of artemisinin was detected. The availability of this simple and highly sensitive pLDH immunodetection assay will provide an easier method for drug susceptibility testing of malaria parasites.

scholarly journals Piperaquine resistant Cambodian Plasmodium falciparum clinical isolates: in vitro genotypic and phenotypic characterization

2020 ◽  
Author(s):  
Nonlawat Boonyalai ◽  
Brian A Vesely ◽  
Chatchadaporn Thamnurak ◽  
Chantida Praditpol ◽  
Watcharintorn Fagnark ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Copy Number ◽  
Drug Susceptibility ◽  
Antagonistic Activity ◽  
Drug Combinations ◽  
Chloroquine Resistance ◽  
Phenotypic Characterization ◽  
Field Isolates

Abstract Background High rates of dihydroartemisinin-piperaquine (DHA-PPQ) treatment failures have been documented for uncomplicated Plasmodium falciparum in Cambodia. The genetic markers plasmepsin 2 ( pfpm2 ), exonuclease ( pfexo ) and chloroquine resistance transporter ( pfcrt ) genes are associated with PPQ resistance and are used for monitoring the prevalence of drug resistance and guiding malaria drug treatment policy.Methods To examine the relative contribution of each marker to PPQ resistance, in vitro culture and the PPQ survival assay were performed on seventeen P. falciparum isolates from northern Cambodia, and the presence of E415G-Exo and pfcrt mutations (T93S, H97Y, F145I, I218F, M343L, C350R, and G353V) as well as pfpm2 copy number polymorphisms were determined. Parasites were then cloned by limiting dilution and the cloned parasites were tested for drug susceptibility. Isobolographic analysis of several drug combinations for standard clones and newly cloned P. falciparum Cambodian isolates was also determined.Results The characterization of culture-adapted isolates revealed that the presence of novel pfcrt mutations (T93S, H97Y, F145I, and I218F) with E415G-Exo mutation can confer PPQ-resistance, in the absence of pfpm2 amplification. In vitro testing of PPQ resistant parasites demonstrated a bimodal dose-response, the existence of a swollen digestive vacuole phenotype, and an increased susceptibility to quinine, chloroquine, mefloquine and lumefantrine. To further characterize drug sensitivity, parental parasites were cloned in which a clonal line, 14-B5, was identified as sensitive to artemisinin and piperaquine, but resistant to chloroquine. Assessment of the clone against a panel of drug combinations revealed antagonistic activity for six different drug combinations. However, mefloquine-proguanil and atovoquone-proguanil combinations revealed synergistic antimalarial activity.Conclusions Surveillance for PPQ resistance in regions relying on DHA-PPQ as the first-line treatment is dependent on the monitoring of molecular markers of drug resistance. P. falciparum harbouring novel pfcrt mutations with E415G-exo mutations displayed PPQ resistant phenotype. The presence of pfpm2 amplification was not required to render parasites PPQ resistant suggesting that the increase in pfpm2 copy number alone is not the sole modulator of PPQ resistance. Genetic background of circulating field isolates appear to play a role in drug susceptibility and biological responses induced by drug combinations. The use of latest field isolates may be necessary for assessment of relevant drug combinations against P. falciparum strains and when down-selecting novel drug candidates.

scholarly journals Molecular Surveillance of Plasmodium falciparum Drug Resistance Markers in Clinical Samples from Botswana

2018 ◽  
Vol 99 (6) ◽  
pp. 1499-1503 ◽  
Author(s):  
Leabaneng Tawe ◽  
Michela Menegon ◽  
Pleasure Ramatlho ◽  
Charles W. Muthoga ◽  
Naledi Mutukwa ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Clinical Samples ◽  
Molecular Surveillance ◽  
Resistance Markers

scholarly journals Artemisinin-independent inhibitory activity of Artemisia sp. infusions against different Plasmodium stages including relapse-causing hypnozoites

2021 ◽  
Vol 5 (3) ◽  
pp. e202101237
Author(s):  
Kutub Ashraf ◽  
Shahin Tajeri ◽  
Christophe-Sébastien Arnold ◽  
Nadia Amanzougaghene ◽  
Jean-François Franetich ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Inhibitory Activity ◽  
Parasite Species ◽  
Artemisia Annua ◽  
Combination Therapies ◽  
Lead Compounds ◽  
Low Concentrations ◽  
Inhibitory Activities

Artemisinin-based combination therapies (ACT) are the frontline treatments against malaria worldwide. Recently the use of traditional infusions from Artemisia annua (from which artemisinin is obtained) or Artemisia afra (lacking artemisinin) has been controversially advocated. Such unregulated plant-based remedies are strongly discouraged as they might constitute sub-optimal therapies and promote drug resistance. Here, we conducted the first comparative study of the anti-malarial effects of both plant infusions in vitro against the asexual erythrocytic stages of Plasmodium falciparum and the pre-erythrocytic (i.e., liver) stages of various Plasmodium species. Low concentrations of either infusion accounted for significant inhibitory activities across every parasite species and stage studied. We show that these antiplasmodial effects were essentially artemisinin-independent and were additionally monitored by observations of the parasite apicoplast and mitochondrion. In particular, the infusions significantly incapacitated sporozoites, and for Plasmodium vivax and P. cynomolgi, disrupted the hypnozoites. This provides the first indication that compounds other than 8-aminoquinolines could be effective antimalarials against relapsing parasites. These observations advocate for further screening to uncover urgently needed novel antimalarial lead compounds.

Effect of Ginkgo biloba extract on rat hepatic microsomal CYP1A activity: role of ginkgolides, bilobalide, and flavonols

2004 ◽  
Vol 82 (1) ◽  
pp. 57-64 ◽  
Author(s):  
I fan Kuo ◽  
Jie Chen ◽  
Thomas K.H Chang
Keyword(s):  
Ginkgo Biloba ◽  
Ginkgo Biloba Extract ◽  
Inhibitory Potency ◽  
Hepatic Microsomes ◽  
Cyp1a Activity ◽  
Ginkgo Biloba Extracts ◽  
The Individual ◽  
Vitro Effect

The present study investigated the in vitro effect of Ginkgo biloba extracts and some of the individual constituents (ginkgolides, bilobalide, and flavonols such as kaempferol, quercetin, isorhamnetin, and their glycosides) on CYP1A-mediated 7-ethoxyresorufin O-dealkylation in hepatic microsomes isolated from rats induced with β-naphthoflavone. G. biloba extract competitively inhibited CYP1A activity, with an apparent Ki value of 1.6 ± 0.4 µg/mL (mean ± SE). At the concentrations present in the G. biloba extracts, ginkgolides A, B, C, and J and bilobalide did not affect CYP1A activity, whereas kaempferol (IC50 = 0.006 ± 0.001 µg/mL, mean ± SE), isorhamnetin (0.007 ± 0.001 µg/mL), and quercetin (0.050 ± 0.003 µg/mL) decreased this activity. The monoglycosides (1 and 10 µg/mL) and diglycosides (10 µg/mL) of kaempferol and quercetin but not those of isorhamnetin also inhibited CYP1A activity. The order of inhibitory potency was kaempferol ~ isorhamnetin > quercetin, and for each of these flavonols the order of potency was aglycone >> monoglycoside > diglycoside. In summary, G. biloba extract competitively inhibited rat hepatic microsomal CYP1A activity, but the effect was not due to ginkgolides A, B, C, or J, bilobalide, kaempferol, quercetin, isorhamnetin, or the respective flavonol monoglycosides or diglycosides.Key words: bilobalide, CYP1A, cytochrome P450, Ginkgo biloba, ginkgolide, flavonol.

PEAK1 promotes invasion and metastasis and confers drug resistance in breast cancer

2021 ◽  
Author(s):  
xingang wang ◽  
YAN ZHENG ◽  
YU WANG
Keyword(s):  
Breast Cancer ◽  
Drug Resistance ◽  
Cell Growth ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Multi Drug Resistance ◽  
Cancer Tissues

Abstract Background and AimsPseudopodium-enriched atypical kinase 1 (PEAK1) has reported to be upregulated in human malignancies and related with poor prognosis. Enhanced PEAK1 expression facilitates tumor cell survival, invasion, metastasis and chemoresistance. However, the role of PEAK1 in breast cancer is not clear. Here, we investigated the PEAK1 expression in breast cancer and analyzed its relation with clinicopathological status and chemotherapy resistance to the neoadjuvant chemotherapy (NAC). We also investigated the role of PEAK1 on breast cancer cells in vitro and in vivo. MethodsImmunohistochemistry (IHC) was performed in 112 surgical resected breast cancer tissues. The associations between clinicopathological status, multi-drug resistance and PEAK1 expression were determined. Effect of PEAK1 overexpression or down-expression on proliferation, colony formation, invasion, migration, metastasis and Doxorubicin sensitivity in the MCF-7 cells in vitro and in vivo was detected. ResultsPEAK1 was overexpressed in breast cancer tissues and NAC -resistant breast cancer tissues. High PEAK1 expression was related with tumor size, high tumor grade, T stage, LN metastasis, recurrence, Ki-67 expression, Her-2 expression and multi-drug resistance. Targeting PEAK1 inhibited cell growth, invasion, metastasis and reversed chemoresistance to Doxorubicin in breast cancer cells in vitro and in vivo. ConclusionHigh PEAK1 expression was associated with invasion, metastasis and chemoresistance of breast cancers. Furthermore, targeting PEAK1 could inhibit cell growth and metastasis, and reverse chemoresistance in breast cancer cells, which provides an effective treatment strategies for breast cancer.

scholarly journals Pre-Clinical Drug Testing in 2D and 3D Human In Vitro Models of Glioblastoma Incorporating Non-Neoplastic Astrocytes: Tunneling Nano Tubules and Mitochondrial Transfer Modulates Cell Behavior and Therapeutic Response

2019 ◽  
Vol 20 (23) ◽  
pp. 6017 ◽  
Author(s):  
Prospero Civita ◽  
Diana M. Leite ◽  
Geoffrey Pilkington
Keyword(s):  
Drug Resistance ◽  
Hyaluronic Acid ◽  
Drug Testing ◽  
Tunneling Nanotubes ◽  
Mitochondrial Transfer ◽  
Culture Models ◽  
And Migration ◽  
2D And 3D

The role of astrocytes in the glioblastoma (GBM) microenvironment is poorly understood; particularly with regard to cell invasion and drug resistance. To assess this role of astrocytes in GBMs we established an all human 2D co-culture model and a 3D hyaluronic acid-gelatin based hydrogel model (HyStem™-HP) with different ratios of GBM cells to astrocytes. A contact co-culture of fluorescently labelled GBM cells and astrocytes showed that the latter promotes tumour growth and migration of GBM cells. Notably, the presence of non-neoplastic astrocytes in direct contact, even in low amounts in co-culture, elicited drug resistance in GBM. Recent studies showed that non-neoplastic cells can transfer mitochondria along tunneling nanotubes (TNT) and rescue damaged target cancer cells. In these studies, we explored TNT formation and mitochondrial transfer using 2D and 3D in vitro co-culture models of GBM and astrocytes. TNT formation occurs in glial fibrillary acidic protein (GFAP) positive “reactive” astrocytes after 48 h co-culture and the increase of TNT formations was greater in 3D hyaluronic acid-gelatin based hydrogel models. This study shows that human astrocytes in the tumour microenvironment, both in 2D and 3D in vitro co-culture models, could form TNT connections with GBM cells. We postulate that the association on TNT delivery non-neoplastic mitochondria via a TNT connection may be related to GBM drug response as well as proliferation and migration.

scholarly journals Molecular detection of drug resistant polymorphisms in Plasmodium falciparum isolates from Southwest, Nigeria

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Monday Tola ◽  
Olumide Ajibola ◽  
Emmanuel Taiwo Idowu ◽  
Olusesan Omidiji ◽  
Samson Taiwo Awolola ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Antimalarial Drug Resistance ◽  
Allelic Discrimination ◽  
Molecular Surveillance ◽  
Malaria Burden ◽  
Two Samples ◽  
Southwest Nigeria ◽  
Resistance Markers ◽  
Drug Interventions

Abstract Objective Nigeria bears 25% of global malaria burden despite concerted efforts towards its control and elimination. The emergence of drug resistance to first line drugs, artemisinin combination therapies (ACTs), indicates an urgent need for continuous molecular surveillance of drug resistance especially in high burden countries where drug interventions are heavily relied on. This study describes mutations in Plasmodium falciparum genes associated with drug resistance in malaria; Pfk13, Pfmdr1, PfATPase6 and Pfcrt in isolates obtained from 83 symptomatic malaria patients collected in August 2014, aged 1–61 years old from South-west Nigeria. Results Two Pfmdr1, N86 and Y184 variants were present at a prevalence of 56% and 13.25% of isolates respectively. There was one synonymous (S679S) and two non-synonymous (M699V, S769M) mutations in the PATPase6 gene, while Pfcrt genotype (CVIET), had a prevalence of 45%. The Pfk13 C580Y mutant allele was suspected by allelic discrimination in two samples with mixed genotypes although this could not be validated with independent isolation or additional methods. Our findings call for robust molecular surveillance of antimalarial drug resistance markers in west Africa especially with increased use of antimalarial drugs as prophylaxis for Covid-19.

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