Hemoglobin E Prevalence among Ethnic Groups Residing in Malaria-Endemic Areas of Northern Thailand and Its Lack of Association with Plasmodium falciparum Invasion In Vitro.

Hemoglobin E (HbE) is one of the most common hemoglobin variants caused by a mutation in the β-globin gene, and found at high frequencies in various Southeast Asian groups. We surveyed HbE prevalence among 8 ethnic groups residing in 5 villages selected for their high period malaria endemicity, and 5 for low endemicity in northern Thailand, in order to uncover factors which may affect genetic persistence of HbE in these groups. We found the overall HbE prevalence 6.7%, with differing frequencies from 0% in the Pwo Karen, the Lawa, and the Skaw Karen to 24% in the Mon. All HbE genes were heterozygous (AE). Differences in HbE prevalence among the studied ethnic groups indirectly documents that ancestries and evolutionary forces, such as drift and admixture, are the important factors in the persistence of HbE distribution in northern Thailand. Furthermore, the presence of HbE in groups of northern Thailand had no effect on the in vitro infectivity and proliferation of Plasmodium falciparum, nor the production of hemozoin, a heme crystal produced by malaria parasites, when compared to normal red-blood-cell controls. Our data may contribute to a better understanding on the persistence of HbE among ethnic groups and its association with malaria

Cell cycle arrest and apoptosis induction by methanolic leaves extracts of four Annonaceae plants

Abstract Background Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders and Dasymaschalon sp. have been used for traditional medicine to treat cancer-like symptoms in some ethnic groups of Thailand and Laos. Methods We evaluated the anti-cancer activity of these Annonaceae plants against several human cancer cell lines. The apoptosis induction was detected by Annexin/propidium iodide (PI) staining. Phytochemical screening was tested by standard protocols and bioactive compounds were determined by HPLC. Results The crude extracts from leaves of U. longipes, Dasymaschalon sp., A. burmanicus, and M. modestum showed particular effects that were found to vary depending on the cancer cell line, suggesting that the effect was in a cell-type specific manner. Interestingly, the induction of apoptotic cell death was prominent by the leaves-derived crude extract of M. modestum. This crude was, therefore, subjected to cell cycle analysis by PI staining. Results showed that this crude extract arrested cell cycle and increased the percentage of cells in the SubG1 phase in some cancer cell lines. The phytochemical screening tests indicated that all crude extracts contained tannins and flavonoids. HPLC of flavonoids using standards identified rutin as an active compound in U. longipes and Dasymaschalon sp., whereas quercetin was found in U. longipes and M. modestum. Conclusions These crude extracts provide a new source for rutin and quercetin, which might be capable of inducing cancer cell apoptotic death in a cell-type specific manner. This suggests, by analyzing the major bioactive compounds, the potential use of these crudes for chemotherapy in the future

Hypermethylation of 28S ribosomal RNA in β-thalassemia trait carriers

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Proportions of studied characteristics (malaria prevalence, HbE, G6PD deficiency, α-thalassemia, β-thalassemia), by village and ethnic group (A) and by linguistic family (B).

<p>Proportions of studied characteristics (malaria prevalence, HbE, G6PD deficiency, α-thalassemia, β-thalassemia), by village and ethnic group (A) and by linguistic family (B).</p

HbE did not have an inhibitory effect on <i>P</i>. <i>falciparum</i> invasion <i>in vitro</i> or the production of hemozoin.

<p>(A) The percentages of infected red blood cells and (B) the absorbance of hemozoin at 450/750 nm after 96 hours incubation of red blood cells from normal (circles) or HbE (diamonds) participants with <i>P</i>. <i>falciparum</i>. Each symbol represents each individual participant. Solid lines show the mean with standard deviations of each group.</p