RESUMEN
Objective To induce a line of Plasmodium berghei with resistance to artemisinin. Methods The major methods included blood transmission from passage to passage and progressive increase of drug pressure. Results The resistant lines were developed by different protocols: (A) The initial dosage of artemisinin was 126^2 mg/kg which was increased by 60 mg/kg for the next passage and boosted by 126^2 mg/kg for every other passage. As developed to passage 60 and 76, the resistant index was 18^39∶1 and 14^89∶1 respectively, then decreased gradually. For passage 108, the dosage was 8 862^5 mg/kg, but the resistant index was only 10^49∶1. (B) Using passage 66 from (A) as the source, a dosage of 4 000 mg/kg was given each week, the resistance of the passage 40 increased significantly with an index of 27^5∶1. (C) Using passage 19 of (B) as the source, drug was administered at the dose of 2 000 mg/kg each week. The resistant index of passage 15 was 17^41∶1. \{ Conclusion \} Line of P.berghei with medium level resistance to artemisinin was established.
RESUMEN
Groups of mice were administered intragastrically either with primaquine alone or in combination with pyronaridine. The number of mice died in groups treated by pyronaridine 293-507 mg/kg combined with primaquine 50 mg/kg were not more than those in group by primaquine alone, but significantly less than those in groups by combination of chloroquine 102-253 mg/kg and primaquine. The tests of primary tissue schizontocidal activity in rhesus monkeys inoculated, with Pladmodium cynomolgi sporozoitcs showed that all monkeys were cured either by treatment of ig primaquine alone, 3 mg/kg/d ? 3, or by a single im dose of pyronaridine 10 mg/kg combined with primaquine starting on the day of infection. No influence of pyronaridine on primaquine was observed in P. yoelii sporozoites-infected mice.