Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Drug resistance is one of the major factors contributing to the resurgence of malaria, especially resistance to the most affordable drugs such as chloroquine and Fansidar, a combination drug of pyrimethamine and sulfadoxine. Understanding the mechanisms of such resistance and developing new treatments, including new drugs, are urgently needed. Great progress has been made recently in studying the mechanisms of drug action and drug resistance in malaria parasites, particularly in Plasmodium falciparum. These efforts are highlighted by the demonstration of mutations in the parasite dihydrofolate reductase and dihydropteroate synthase genes conferring resistance to pyrimethamine and sulfadoxine, respectively, and by the recent discovery of mutations in the gene coding for a putative transporter, PfCRT, conferring resistance to chloroquine. Mutations in a homologue of a human multiple-drug-resistant gene, pfmdr1, have also been shown to be associated with responses to multiple drugs. However, except in the case of resistance to antifolate drugs, the mechanisms of action and resistance to most drugs currently in use are essentially unknown or are being debated. Additionally, novel mechanisms of resistance exist in different malaria parasites, complicating the process of developing new drugs and treatment strategies. Here we summarise the progress made in drug resistance research in malaria parasites over the past 20 years, emphasising the most recent developments in the genetics of drug resistance.
 ...
PMID:Genetic and biochemical aspects of drug resistance in malaria parasites. 1503 30

We monitored post-treatment Plasmodium falciparum among patients treated with chloroquine (CQ) and sulfadoxine-pyrimethamine (SP; Fansidar in a village in eastern Sudan. Parasites were examined on day 0 (pre-treatment), day 7, day 14 and day 21 (post-treatment) during the transmission season. A further sample was taken 2 months later (day 80) at the start of the dry season. Asexual forms and gametocytes were detected by microscopy, and reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect expression of gametocyte-specific proteins pfs 25 and pfg 377. Gametocyte carriage, as revealed by microscopy, increased significantly following CQ and SP treatment, reaching a maximum between days 7 and 14. When measured by RT-PCR, however, there was no significant difference in gametocyte rate between day 0 and days 7 or 14. RT-PCR gametocyte rates dropped dramatically by day 80 post treatment but were still 33% and 8% in the CQ- and SP-treated group at this time. Alleles associated with drug resistance of P. falciparum to chloroquine (the chloroquine resistance transporter, pfcrt, and multidrug resistance, pfmdr1) and to pyrimethamine (dihydrofolate reductase, dhfr) were seen at a high frequency at the beginning of treatment and increased further through time following both drug treatments. Infections with drug-resistant parasites tended to have higher gametocyte prevalence than drug-sensitive infections.
 ...
PMID:Increased density but not prevalence of gametocytes following drug treatment of Plasmodium falciparum. 1625 26


<< Previous 1 2