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  1 / 5644 MEDLINE  
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PMID:29320822
Autor:Park GM; Park H; Oh S; Lee S
Endereço:Department of Medical Environmental Biology, Catholic Kwandong University College of Medicine, Gangneung 25601, Korea.
Título:Antimalarial Activity of C-10 Substituted Triazolyl Artemisinin.
Fonte:Korean J Parasitol; 55(6):661-665, 2017 Dec.
ISSN:1738-0006
País de publicação:Korea (South)
Idioma:eng
Resumo:We synthesized C-10 substituted triazolyl artemisinins by the Huisgen cycloaddition reaction between dihydroartemisinins (2) and variously substituted 1, 2, 3-triazoles (8a-8h). The antimalarial activities of 32 novel artemisinin derivatives were screened against a chloroquine-resistant parasite. Among them, triazolyl artemisinins with electron-withdrawing groups showed stronger antimalarial activities than those shown by the derivatives having electron-donating groups. In particularly, m-chlorotriazolyl artemisinin (9d-12d) showed antimalarial activity equivalent to that of artemisinin and could be a strong drug candidate.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Triazoles); 6A9O50735X (dihydroartemisinin)


  2 / 5644 MEDLINE  
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PMID:28460126
Autor:Izevbekhai O; Adeagbo B; Olagunju A; Bolaji O
Endereço:Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
Título:Quality of artemisinin-based antimalarial drugs marketed in Nigeria.
Fonte:Trans R Soc Trop Med Hyg; 111(2):90-96, 2017 02 01.
ISSN:1878-3503
País de publicação:England
Idioma:eng
Resumo:Background: Artemisinin combination therapy is first-line therapy for treatment of malaria, which is one of the most significant public health problems in Nigeria. With the increasing level of use of these drugs coupled with the emergence of resistance, there is a need for regular post-market surveillance. Method: Twenty different brands of artesunate-containing antimalarial drugs and 10 brands of artemether-lumefantrine were multi-sourced in the south western part of Nigeria and were subjected to identification, weight uniformity test, and assay using United State pharmacopoeia and International Pharmacopoeia monographs. In vitro-dissolution test of the artemether tablets was also investigated. Results: All 10 brands (100%) of the artemether-lumefantrine tablets met the assay requirement for artemether and 8 (80%) met the assay requirement for lumefantrine, but only 4 brands (40%) met the requirement for artemether dissolution. One of these brands failed the weight uniformity test. Of the 20 brands of artesunate-containing brands included in this study, 15 (75%) met the standard assay requirement for artesunate and two failed the weight uniformity test. Conclusions: There is evidence of the presence of substandard artemisinin products in the Nigerian market.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Drug Combinations); 0 (Ethanolamines); 0 (Fluorenes); 0 (artemether-lumefantrine combination); 60W3249T9M (artesunate)


  3 / 5644 MEDLINE  
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PMID:28460112
Autor:Aponte S; Guerra ÁP; Álvarez-Larrotta C; Bernal SD; Restrepo C; González C; Yasnot MF; Knudson-Ospina A
Endereço:Grupo de Bioquímica y Biología Celular, Instituto Nacional de Salud, Bogotá, D.C., Colombia.
Título:Baseline in vivo, ex vivo and molecular responses of Plasmodium falciparum to artemether and lumefantrine in three endemic zones for malaria in Colombia.
Fonte:Trans R Soc Trop Med Hyg; 111(2):71-80, 2017 02 01.
ISSN:1878-3503
País de publicação:England
Idioma:eng
Resumo:Background: Colombia began using artemisinin-based combination therapies for the treatment of uncomplicated Plasmodium falciparum malaria in 2006. It is necessary to implement resistance surveillance to antimalarial drugs in order to promptly detect changes in parasite susceptibility. The aim of this study was to establish a susceptibility baseline of P. falciparum to artemether-lumefantrine using three monitoring tools. Methods: Patients with uncomplicated malaria treated with artemether-lumefantrine underwent clinical and parasitological follow-up over 28 days. Ex vivo test was performed using the microtest technique for chloroquine, arthemeter, dihydroartemisinin and lumefantrine. Pfmdr1 copy number and polymorphisms in Pfk13, Pfatp6, Pfcrt and Pfmdr1 genes were analyzed. Results: From a total of 150 screened patients, 49 completed follow-up for 28 days. All treated patients had adequate clinical and parasitological responses. Parasitic clearance showed a drastic reduction of parasite biomass at 24 hours and complete elimination at 48 hours. One hundred eleven isolates were processed, all exhibited high susceptibility to artemisinins and a slight decrease in susceptibility to lumefantrine. No genetic polymorphisms associated with resistance to artemisinin were found. Conclusion: This study generated a susceptibility baseline in response to therapy with Coartem (artemether-lumefantrine) with numerical reference values, which will allow data comparison with future studies to systematically monitor changes in the parasite and to provide an early alert to the health authorities.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Drug Combinations); 0 (Ethanolamines); 0 (Fluorenes); 0 (Protozoan Proteins); 0 (artemether-lumefantrine combination); C7D6T3H22J (artemether); F38R0JR742 (lumefantrine)


  4 / 5644 MEDLINE  
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PMID:29280362
Autor:Zhang J; Feng GH; Zou CY; Su PC; Liu HE; Yang ZQ
Endereço:Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming Yunnan 650500, China.
Título:Overview of the improvement of the ring-stage survival assay-a novel phenotypic assay for the detection of artemisinin-resistant .
Fonte:Zool Res; 38(6):317-320, 2017 Nov 18.
ISSN:2095-8137
País de publicação:China
Idioma:eng
Resumo:Artemisinin resistance in threatens the remarkable efficacy of artemisinin-based combination therapies worldwide. Thus, greater insight into the resistance mechanism using monitoring tools is essential. The ring-stage survival assay is used for phenotyping artemisinin-resistance or decreased artemisinin sensitivity. Here, we review the progress of this measurement assay and explore its limitations and potential applications.
Tipo de publicação: JOURNAL ARTICLE; REVIEW
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 9RMU91N5K2 (artemisinine)


  5 / 5644 MEDLINE  
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PMID:28467668
Autor:Kavishe RA; Koenderink JB; Alifrangis M
Endereço:Department of Biochemistry & Molecular Biology, Faculty of Medicine, Kilimanjaro Christian Medical University College, Moshi, Tanzania.
Título:Oxidative stress in malaria and artemisinin combination therapy: Pros and Cons.
Fonte:FEBS J; 284(16):2579-2591, 2017 08.
ISSN:1742-4658
País de publicação:England
Idioma:eng
Resumo:Artemisinin-based combination therapy (ACT) has been adopted as a strategy to mitigate multidrug resistance to antimalarial monotherapies. ACT combines the rapid and effective but rather short plasma half-life antimalarial action of an artemisinin derivative with a longer acting partner drug. Although the exact mechanisms of action of artemisinins are not well understood, several studies have proposed multiple cellular targets of artemisinins with involvement of reactive oxygen species (ROS). Most of the currently used ACT partner drugs are also known to involve ROS production in their mechanisms of action. This review gives a brief account of the oxidative stress and redox systems in malaria and discusses the context of antimalarial effectiveness of different ACTs compared with monotherapies of the partner drugs. A final account on the Pros and Cons of ACT as a strategy is discussed.
Tipo de publicação: JOURNAL ARTICLE; REVIEW
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Reactive Oxygen Species)


  6 / 5644 MEDLINE  
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PMID:28450175
Autor:Madamet M; Kounta MB; Wade KA; Lo G; Diawara S; Fall M; Bercion R; Nakoulima A; Fall KB; Benoit N; Gueye MW; Fall B; Diatta B; Pradines B
Endereço:Unité de parasitologie et d'entomologie, Département des maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France; Aix-Marseille Université, Unité de recherche sur les maladies infectieuses et tropicales emergentes (URMITE), UM 63, CNRS 7278, IRD 198, Inserm 1095, Marse
Título:Absence of association between polymorphisms in the K13 gene and the presence of Plasmodium falciparum parasites at day 3 after treatment with artemisinin derivatives in Senegal.
Fonte:Int J Antimicrob Agents; 49(6):754-756, 2017 Jun.
ISSN:1872-7913
País de publicação:Netherlands
Idioma:eng
Resumo:In 2006, the Senegalese National Malaria Control Programme recommended artemisinin-based combination therapy as first-line treatment for uncomplicated malaria. In addition, intravenous (i.v.) injection of artesunate and artemether has gradually replaced quinine for the treatment of severe malaria. Mutations in the propeller domain of the Kelch 13 gene (K13-propeller, PF3D71343700), such as Y493H, R539T, I543T and C580Y, were recently associated with in vivo and in vitro resistance to artemisinin in Southeast Asia. However, these mutations were not identified in Africa. In total, 181 isolates of Plasmodium falciparum from 161 patients from Dakar, Senegal, were collected between August 2015 and January 2016. The K13-propeller gene of the isolates was sequenced. A search for non-synonymous mutations in the propeller region of K13 was performed in the 181 isolates collected from Dakar from 2015 to 2016. Three synonymous mutations were detected (D464D, C469C and R471R). Of 119 patients treated with i.v. artesunate or intramuscular artemether followed by artemether/lumefantrine, 9 patients were still parasitaemic on Day 3. Parasites from these nine patients were wild-type for K13-propeller. None of the polymorphisms known to be involved in artemisinin resistance in Asia were detected. These results suggest that K13 is not the best predictive marker for artemisinin resistance in Africa. More isolates from clinical failure cases or patients with delayed parasite clearance after treatment with artemisinin derivatives are necessary to identify new molecular markers.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Protozoan Proteins); 9RMU91N5K2 (artemisinine)


  7 / 5644 MEDLINE  
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PMID:29342187
Autor:De Lucia S; Tsamesidis I; Pau MC; Kesely KR; Pantaleo A; Turrini F
Endereço:Department of Oncology, University of Turin, Turin, Italy.
Título:Induction of high tolerance to artemisinin by sub-lethal administration: A new in vitro model of P. falciparum.
Fonte:PLoS One; 13(1):e0191084, 2018.
ISSN:1932-6203
País de publicação:United States
Idioma:eng
Resumo:Artemisinin resistance is a major threat to malaria control efforts. Resistance is characterized by an increase in the Plasmodium falciparum parasite clearance half-life following treatment with artemisinin-based combination therapies (ACTs) and an increase in the percentage of surviving parasites. The remarkably short blood half-life of artemisinin derivatives may contribute to drug-resistance, possibly through factors including sub-lethal plasma concentrations and inadequate exposure. Here we selected for a new strain of artemisinin resistant parasites, termed the artemisinin resistant strain 1 (ARS1), by treating P. falciparum Palo Alto (PA) cultures with sub-lethal concentrations of dihydroartemisinin (DHA). The resistance phenotype was maintained for over 1 year through monthly maintenance treatments with low doses of 2.5 nM DHA. There was a moderate increase in the DHA IC50 in ARS1 when compared with parental strain PA after 72 h of drug exposure (from 0.68 nM to 2 nM DHA). In addition, ARS1 survived treatment physiologically relevant DHA concentrations (700 nM) observed in patients. Furthermore, we confirmed a lack of cross-resistance against a panel of antimalarials commonly used as partner drugs in ACTs. Finally, ARS1 did not contain Pfk13 propeller domain mutations associated with ART resistance in the Greater Mekong Region. With a stable growth rate, ARS1 represents a valuable tool for the development of new antimalarial compounds and studies to further elucidate the mechanisms of ART resistance.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (DNA, Protozoan); 9RMU91N5K2 (artemisinine)


  8 / 5644 MEDLINE  
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PMID:28454557
Autor:Cerqueira GC; Cheeseman IH; Schaffner SF; Nair S; McDew-White M; Phyo AP; Ashley EA; Melnikov A; Rogov P; Birren BW; Nosten F; Anderson TJC; Neafsey DE
Endereço:Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
Título:Longitudinal genomic surveillance of Plasmodium falciparum malaria parasites reveals complex genomic architecture of emerging artemisinin resistance.
Fonte:Genome Biol; 18(1):78, 2017 04 28.
ISSN:1474-760X
País de publicação:England
Idioma:eng
Resumo:BACKGROUND: Artemisinin-based combination therapies are the first line of treatment for Plasmodium falciparum infections worldwide, but artemisinin resistance has risen rapidly in Southeast Asia over the past decade. Mutations in the kelch13 gene have been implicated in this resistance. We used longitudinal genomic surveillance to detect signals in kelch13 and other loci that contribute to artemisinin or partner drug resistance. We retrospectively sequenced the genomes of 194 P. falciparum isolates from five sites in Northwest Thailand, over the period of a rapid increase in the emergence of artemisinin resistance (2001-2014). RESULTS: We evaluate statistical metrics for temporal change in the frequency of individual SNPs, assuming that SNPs associated with resistance increase in frequency over this period. After Kelch13-C580Y, the strongest temporal change is seen at a SNP in phosphatidylinositol 4-kinase, which is involved in a pathway recently implicated in artemisinin resistance. Furthermore, other loci exhibit strong temporal signatures which warrant further investigation for involvement in artemisinin resistance evolution. Through genome-wide association analysis we identify a variant in a kelch domain-containing gene on chromosome 10 that may epistatically modulate artemisinin resistance. CONCLUSIONS: This analysis demonstrates the potential of a longitudinal genomic surveillance approach to detect resistance-associated gene loci to improve our mechanistic understanding of how resistance develops. Evidence for additional genomic regions outside of the kelch13 locus associated with artemisinin-resistant parasites may yield new molecular markers for resistance surveillance, which may be useful in efforts to reduce the emergence or spread of artemisinin resistance in African parasite populations.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Protozoan Proteins); 9RMU91N5K2 (artemisinine)


  9 / 5644 MEDLINE  
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PMID:27773251
Autor:Chemat S; Aissa A; Boumechhour A; Arous O; Ait-Amar H
Endereço:Extraction & Separation Techniques Team, Centre de Recherches Scientifique et Technique en Analyses Physico-Chimiques (C.R.A.P.C.), BP 248 Alger RP 16004, Algiers, Algeria. Electronic address: chemats@yahoo.fr.
Título:Extraction mechanism of ultrasound assisted extraction and its effect on higher yielding and purity of artemisinin crystals from Artemisia annua L. leaves.
Fonte:Ultrason Sonochem; 34:310-316, 2017 01.
ISSN:1873-2828
País de publicação:Netherlands
Idioma:eng
Resumo:This study proposes an ultrasound-horn system for the extraction of a natural active compound "artemisinin" from Artemisia annua L. leaves as an alternative to hot maceration technique. Ultrasound leaching improves artemisinin recovery at all temperatures where only ten minutes is required to recover 70% (4.42mgg ) compared to 60min of conventional hot leaching for the same yield. For instance, ultrasound treatment at 30°C produced a higher yield than the one obtained by conventional maceration at 40°C. Kinetic study suggests that the extraction pattern can be assimilated, during the first ten minutes, to a first order steady state, from which activation energy calculations revealed that each gram of artemisinin required 7.38kJ in ultrasound versus 10.3kJ in the conventional system. Modeling results indicate the presence of two extraction stages, a faster stage with a diffusion coefficient of 19×10 cm min for ultrasound technique at 40°C, seven times higher than the conventional one; and a second deceleration stage similar for both techniques with diffusion coefficient ranging from 1.7 to 3.1×10 cm min . It is noted that the efficient ultrasound extraction potential implies extraction of higher amount of co-metabolites so low artemisinin crystal purity is engendered but a combination with a purification step using activated charcoal and celite adsorbents produced crystals with comparable purity for conventional and ultrasound samples.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Artemisinins); 9RMU91N5K2 (artemisinine)


  10 / 5644 MEDLINE  
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PMID:27776521
Autor:Denoeud-Ndam L; Dicko A; Baudin E; Guindo O; Grandesso F; Diawara H; Sissoko S; Sanogo K; Traoré S; Keita S; Barry A; de Smet M; Lasry E; Smit M; Wiesner L; Barnes KI; Djimde AA; Guerin PJ; Grais RF; Doumbo OK; Etard JF
Endereço:Epicentre, Paris, France. lise.denoeud@epicentre.msf.org.
Título:Efficacy of artemether-lumefantrine in relation to drug exposure in children with and without severe acute malnutrition: an open comparative intervention study in Mali and Niger.
Fonte:BMC Med; 14(1):167, 2016 10 24.
ISSN:1741-7015
País de publicação:England
Idioma:eng
Resumo:BACKGROUND: Severe acute malnutrition (SAM) affects almost all organs and has been associated with reduced intestinal absorption of medicines. However, very limited information is available on the pharmacokinetic properties of antimalarial drugs in this vulnerable population. We assessed artemether-lumefantrine (AL) clinical efficacy in children with SAM compared to those without. METHODS: Children under 5 years of age with uncomplicated P. falciparum malaria were enrolled between November 2013 and January 2015 in Mali and Niger, one third with uncomplicated SAM and two thirds without. AL was administered under direct observation with a fat intake consisting of ready-to-use therapeutic food (RUTF - Plumpy'Nut®) in SAM children, twice daily during 3 days. Children were followed for 42 days, with PCR-corrected adequate clinical and parasitological response (ACPR) at day 28 as the primary outcome. Lumefantrine concentrations were assessed in a subset of participants at different time points, including systematic measurements on day 7. RESULTS: A total of 399 children (360 in Mali and 39 in Niger) were enrolled. Children with SAM were younger than their non-SAM counterparts (mean 17 vs. 28 months, P < 0.0001). PCR-corrected ACPR was 100 % (95 % CI, 96.8-100 %) in SAM at both day 28 and 42, versus 98.8 % (96.4-99.7 %) at day 28 and 98.3 % (95.6-99.4 %) at day 42 in non-SAM (P = 0.236 and 0.168, respectively). Compared to younger children, children older than 21 months experienced more reinfections and SAM was associated with a greater risk of reinfection until day 28 (adjusted hazard ratio = 2.10 (1.04-4.22), P = 0.038). Day 7 lumefantrine concentrations were significantly lower in SAM than non-SAM (median 251 vs. 365 ng/mL, P = 0.049). CONCLUSIONS: This study shows comparable therapeutic efficacy of AL in children without SAM and in those with SAM when given in combination with RUTF, but a higher risk of reinfection in older children suffering from SAM. This could be associated with poorer exposure to the antimalarials as documented by a lower lumefantrine concentration on day 7. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01958905 , registration date: October 7, 2013.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Antimalarials); 0 (Artemisinins); 0 (Drug Combinations); 0 (Ethanolamines); 0 (Fluorenes); 0 (artemether-lumefantrine combination)



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