{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,22]],"date-time":"2025-10-22T17:32:57Z","timestamp":1761154377499},"reference-count":0,"publisher":"Cambridge University Press (CUP)","issue":"3","license":[{"start":{"date-parts":[[1997,9,1]],"date-time":"1997-09-01T00:00:00Z","timestamp":873072000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasitology"],"published-print":{"date-parts":[[1997,9]]},"abstract":"<jats:p>The combination of pyrimethamine and sulfadoxine (PSD or \nFansidar) represents one of the most important chemo-\ntherapeutic agents currently used to treat falciparum malaria. To \ninvestigate the molecular basis of resistance to PSD, \nreliable <jats:italic>in vitro<\/jats:italic> drug assays are required to permit \ncorrelation of resistance levels with different genotypes. We describe \nhere protocols that permit accurate evaluation of IC<jats:sub>50<\/jats:sub> values \nfor sulfadoxine (SDX) inhibition of <jats:italic>Plasmodium falciparum<\/jats:italic>. \nHistorically, tests for this drug have suffered from poor reproducibility \nand extreme variability in reported values. We \nhave examined a series of variables, including serum-containing \nversus serum-free media, erythrocyte source, pre-test \ngrowth conditions, test components and post-test processing. We define \nconditions which better control the levels of the \ndrug antagonists folate and <jats:italic>p<\/jats:italic>-aminobenzoate, yielding \nreproducible differences between lines of <jats:italic>P. falciparum<\/jats:italic> with \ndiffering alleles of the dihydropteroate synthetase gene, which encodes \nthe target enzyme of SDX. We also use this assay \nto demonstrate a marked difference in the response of different parasite \nlines to antagonism of SDX inhibition by \nexogenous folate. The ability to measure reliable IC<jats:sub>50<\/jats:sub> \nvalues for SDX inhibition should greatly facilitate further \nexperiments to explore the molecular basis of Fansidar resistance.<\/jats:p>","DOI":"10.1017\/s0031182097001431","type":"journal-article","created":{"date-parts":[[2002,7,27]],"date-time":"2002-07-27T09:30:22Z","timestamp":1027762222000},"page":"223-230","source":"Crossref","is-referenced-by-count":49,"title":["A modified <i>in vitro<\/i> sulfadoxine susceptibility assay for \n<i>Plasmodium falciparum<\/i> suitable for investigating Fansidar resistance"],"prefix":"10.1017","volume":"115","author":[{"given":"P.","family":"WANG","sequence":"first","affiliation":[]},{"given":"P. F. G.","family":"SIMS","sequence":"additional","affiliation":[]},{"given":"J. E.","family":"HYDE","sequence":"additional","affiliation":[]}],"member":"56","published-online":{"date-parts":[[1997,9,1]]},"container-title":["Parasitology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0031182097001431","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,5,11]],"date-time":"2019-05-11T16:22:30Z","timestamp":1557591750000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0031182097001431\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1997,9]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1997,9]]}},"alternative-id":["S0031182097001431"],"URL":"https:\/\/doi.org\/10.1017\/s0031182097001431","relation":{},"ISSN":["0031-1820","1469-8161"],"issn-type":[{"value":"0031-1820","type":"print"},{"value":"1469-8161","type":"electronic"}],"subject":[],"published":{"date-parts":[[1997,9]]}}}