Karl H. Rieckmann

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Atovaquone is the major active component of the new antimalarial drug Malarone. Considerable evidence suggests that malaria parasites become resistant to atovaquone quickly if atovaquone is used as a sole agent. The mechanism by which the parasite develops resistance to atovaquone is not yet fully understood. Atovaquone has been shown to inhibit the(More)
Plasmodium vivax infections are characterized by varying numbers of relapses occurring at different intervals as a result of activation of liver-stage hypnozoites. Parasite or host factors that determine the number and timing of relapses are unclear. In the present article, we report the analysis of relapse patterns and molecular characterization of(More)
Three human volunteers were successfully protected against sporozoite challenge by immunization with attenuated sporozoites of the Tamenie strain of Plasmodium falciparum from Ethiopia. The immunizing sporozoites were attenuated by exposing infected Anopheles stephensi mosquitos to X-rays at a dose of at least 120 Gy (12 000 rad). These irradiated, infected(More)
Studies conducted between 1971 and 1975 showed that attenuated sporozoites can induce protection against human malaria. Three volunteers were protected against challenge with either a homologous or heterologous strain of Plasmodium falciparum after being exposed to a total of 440-987 X-irradiated mosquitos on 6-8 occasions over a period of 10-38 weeks.(More)
The prevalence of putative poor metaboliser (PM) phenotypes of proguanil oxidation in Caucasian populations is 3-10%. The PM frequency in Oriental populations is unknown. In this study the plasma metabolic ratios of proguanil and dapsone to their principal metabolites cycloguanil and monoacetyldapsone were determined in Thai soldiers receiving antifolate(More)
OBJECTIVES To assess the antimalarial pharmacodynamics and pharmacokinetics of the novel dihydrofolate reductase (DHFR) inhibitor, JPC2056 and its principal active metabolite JPC2067 in cynomolgus monkeys using an in vivo-in vitro model. METHODS In a two-phase crossover design, five cynomolgus monkeys were administered a single dose (20 mg/kg) and(More)