Mahidol University

About: Mahidol University is a education organization based out in Bangkok, Nakhon Pathom, Thailand. It is known for research contribution in the topics: Population & Malaria. The organization has 23758 authors who have published 39761 publications receiving 878781 citations.

Genome-wide association study identifies susceptibility loci for dengue shock syndrome at MICB and PLCE1

Abstract: Hypovolemic shock (dengue shock syndrome (DSS)) is the most common life-threatening complication of dengue. We conducted a genome-wide association study of 2,008 pediatric cases treated for DSS and 2,018 controls from Vietnam. Replication of the most significantly associated markers was carried out in an independent Vietnamese sample of 1,737 cases and 2,934 controls. SNPs at two loci showed genome-wide significant association with DSS. We identified a susceptibility locus at MICB (major histocompatibility complex (MHC) class I polypeptide-related sequence B), which was within the broad MHC region on chromosome 6 but outside the class I and class II HLA loci (rs3132468, P(meta) = 4.41 × 10(-11), per-allele odds ratio (OR) = 1.34 (95% confidence interval: 1.23-1.46)). We identified associated variants within PLCE1 (phospholipase C, epsilon 1) on chromosome 10 (rs3765524, P(meta) = 3.08 × 10(-10), per-allele OR = 0.80 (95% confidence interval: 0.75-0.86)). We identify two loci associated with susceptibility to DSS in people with dengue, suggesting possible mechanisms for this severe complication of dengue.

Effect of charged and non-ionic membrane additives on physicochemical properties and stability of niosomes.

Abstract: The aim of this study was to investigate an influence of different types of membrane additives including negative charge (dicetylphosphate, DCP), positive charge (stearylamine, STR) and non-ionic molecule (cholesteryl poly-24-oxyethylene ether, SC24) on the physicochemical properties of drug-free and drug-loaded niosomes. Salicylic acid having different proportions of ionized and unionized species at different pH was selected as a model drug. The niosomes were composed of 1:1 mole ratio of Span 60: cholesterol as vesicle forming agents. The results show that incorporation of salicylic acid to the niosomes did not affect zeta potential values; however, addition of the membrane additives changed the zeta potential depending on the type of the additives. Transmission electron microscopy revealed that niosomes had unilamellar structure. The particle sizes of all developed niosomes were between 217 to 360 nm. The entrapment efficiency (%E.E.) of all salicylic acid niosomes at pH 3 was higher than that of niosomes at pH 5, indicating that salicylic acid in unionized form was preferably incorporated in niosomes. Furthermore, the positively charged niosomes showed the highest %E.E. of salicylic acid owing to electrostatic attraction between STR and salicylic acid. After 3 months of storage at 4°C, the particle size of the niosomes remained in the nanosize range except for DCP salicylic acid niosomes at pH 3 whose size increased due to an instability of DCP at low pH. In addition, all niosomes showed no leakage of the salicylic acid after 3 months of storage indicating the good stability.

The Deformability of Red Blood Cells Parasitized by Plasmodium falciparum and P. vivax

Abstract: Red blood cells (RBCs) must deform considerably during their multiple passages through the microvasculature and the sinusoids of the spleen. RBCs infected with Plasmodium falciparum (Pf-IRBCs) become increasingly rigid as they mature but avoid splenic clearance by sequestering in venules and capillaries. In contrast, RBCs infected with P. vivax (Pv-IRBCs) do not sequester. We compared the effects of P. vivax and P. falciparum infection on RBC deformability in a laminar shear flow system. Pf-IRBCs became more rigid as the parasite matured, but equivalent maturation of Pv-IRBCs resulted in a doubling of flexibility. Coincidentally, the IRBC surface area increased from 56.7+/-1.3 microm2 to 74.7+/-0.6 microm2 to 90.9+/-1.1 microm2 in ring-, trophozoite-, and schizont-stage Pv-IRBCs, respectively, whereas Pf-IRBCs did not increase in size. P. vivax increases the deformability of IRBCs and thereby avoids splenic entrapment.

Distribution and Diversity of Wolbachia Infections in Southeast Asian Mosquitoes (Diptera: Culicidae)

Abstract: Wolbachia are a group of intracellular inherited bacteria that infect a wide range of arthropods. They are associated with a variety of reproductive alterations in their hosts, the best known being cytoplasmic incompatability. The Wolbachia pipientis assemblage has been divided into two major groups (A and B) and 12 subgroups. We report herein the first systematic survey of Wolbachia in mosquitoes, and the first survey classifying Wolbachia infections by subgroup. Wolbachia were detected in 28.1% of 89 wild-caught mosquito species, based on a polymerase chain reaction assay using ftsZ and wsp gene primers. Infections were found in all major disease vector genera except Anopheles. Nine of the 12 Wolbachia subgroups were represented. Group B Wolbachia strains showed more phylogenetic concordance with their host taxa than group A strains. Of the 25 positive mosquito species, five were superinfected with group A bacteria strains (AA), eight were superinfected with A and B strains (AB), and one was superinfected with group B strains (BB). The widespread distribution of Wolbachia among mosquito species further supports their potential importance in the genetic control of disease vectors.