Dihydrofolate reductase (DHFR; EC1.5.1.3) is a known target enzyme for antifolate agents, which are used as alternative chemotherapeutics for chloroquine-resistant malaria. Mutations in the dhfr gene of Plasmodium vivax are thought to be associated with resistance to the antifolate drugs. In this study, we have analyzed genetic variations in the dhfr genes of clinical isolates of P. vivax (n=21) in Myanmar, to monitor antifolate resistance in this country. Sequence variations within the entire dhfr gene were highly restricted to codons from 57 to 117, and the GGDN tandem repeat region. Double (S58R and S117N/T) or quadruple mutations (F57L/I, S58R, T61M, and S117N/T), which may be closely related to the drug resistance, were recognized in most of the isolates (20/21 cases). Our results suggest that antifolate-resistant P. vivax is becoming widespread in Myanmar, as it also is in the neighboring countries in Southeast Asia. It appears that the drug resistance situation may be worsening in the country.

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Increasing data from early Korean Palaeolithic assemblages have challenged the validity of traditional paradigms. This article summarizes previous models and addresses recently raised questions regarding the synthesis of early toolkits. Determining chronologies, cultural markers, and regional cultural traits were our primary objectives. The applicability of the traditional Western Palaeolithic chronology (Lower, Middle, Upper) to East Asian contexts has recently been questioned, in conjunction with an effort to identify more discrete chronological changes in East Asia. The discourse related to cultural identities within East Asia has underscored the importance of spatially and temporally differing values. The morphology and metrics of Korean hand axes have not been considered typical Acheulean. In addition, temporal persistence is an issue; it has caused the conventional culture-historical orthodoxy to be questioned. Discourses on expedient lithic reduction and a static lithic sequence have been considered indicative of discrete cultural entities in the Korean Palaeolithic. Oldowan-like simple core and flake assemblages and the sporadic occurrence of hand axe assemblages in East Asia were traditionally regarded to be chronologically and culturally separate entities. The growing body of archaeological data for Korea has allowed analysis of the occupational contemporaneity and cultural subordination and independence of chopping tool and hand axe assemblages. The Korean Early Palaeolithic is not standardized and does not conform to traditional typologies. Consequently, the directional perspectives applied to these assemblages need to be reevaluated.