One- and Two-Dimensional CP/MAS 13C NMR Analyses of Dynamics in Poly(2-hydroxypropyl ether of bisphenol-A) (FUNDAMENTAL MATERIAL PROPERTIES-Molecular Dynamic Characterisitics)

The dynamics of amorphous poly(2-hydroxypropyl ether of bisphenol-A) (PHR), quenched from the melt, has been investigated by one- and two-dimensional solid-state 13C NMR spectroscopy. CP/MAS 13C NMR spectra from .150 to 180 oC give two specific features: (1) below 23 oC, resonance lines for CH carbons of phenylene rings split into two lines; (2) linewidths of resonance lines become broad at 20 - 50 oC above the glass transition temperature. The feature (1) indicates that phenylene C-H carbons exist in chemically different two sites at low temperatures. These two sites are probably associated with OH … hydrogen bond formation. The coalescence of the resonance lines at elevated temperatures is caused by flip motion of phenylene rings, which corresponds to the relaxation for PHR. The correlation time of the flip motion is analyzed by the two-site exchange model, and is found to follow the Arrhenius equation. The apparent activation energy is 51 kJ mol-1 by assuming an inhomogeneous correlation time distribution described by a Kohlrausch-Williams-Watts (KWW) function with an exponent of 0.2. The feature (2) is caused by the so-called motional broadening, which is originated by enhanced segmental motions. This dynamics corresponds to the relaxation for PHR and can be described by William-Landel-Ferry (WLF) equation. Two-dimensional CP/MAS 13C exchange NMR experiments confirm the existence of flip angle distribution as well as the distribution of correlation times of phenylene ring flip motion with a KWW exponent of 0.2

Recent increase of genetic diversity in Plasmodium vivax population in the Republic of Korea

<p>Abstract</p> <p>Background</p> <p>The reemergence of <it>Plasmodium vivax </it>in South Korea since 1993 represents a serious public health concern. Despite the importance in understanding genetic diversity for control strategies, however, studies remain inconclusive with the general premise that due to low rate of malaria transmission, there is generally low genetic diversity with very few strains involved. In this study, the genetic diversity and population structure of <it>P. vivax </it>in South Korea were explored by analysing microsatellite polymorphism.</p> <p>Methods</p> <p>Sequences for 13 microsatellite loci distributed across the twelve chromosomes of <it>P. vivax </it>were obtained from 58 South Korean isolates collected during two sampling periods, namely 1997-2000 and 2007. The sequences were used for the analysis of expected heterozygosity and multilocus genotype diversity. Population structure was evaluated using STRUCTURE version 2.3.2. Linkage disequilibrium was also analysed to investigate the extent of outbreeding in the <it>P. vivax </it>population.</p> <p>Results</p> <p>Mean expected heterozygosity significantly increased from 0.382 in 1997-2000 to 0.545 in 2007 (<it>P </it>< 0.05). The number of multilocus genotypes was 7 and 27; and genotype diversity was statistically significant (<it>P </it>< 0.01) at 0.661 and 0.995 in 1997-2000 and 2007, respectively. Analysis by STRUCTURE showed a more complex population structure in 2007 than in 1997-2000. Linkage disequilibrium between 13 microsatellites, although significant in both time points, was notably lower in 2007.</p> <p>Conclusions</p> <p>The present microsatellite analysis clearly showed recent increase of genetic diversity and recent relaxation of the strong population structure observed in 1997-2000. These results suggest that multiple genotypes not present previously recently migrated into South Korea, accompanied by substantial outbreeding between different genotypes.</p

Rapid and Highly Sensitive Detection of Malaria-Infected Erythrocytes Using a Cell Microarray Chip

BACKGROUND: Malaria is one of the major human infectious diseases in many endemic countries. For prevention of the spread of malaria, it is necessary to develop an early, sensitive, accurate and conventional diagnosis system. METHODS AND FINDINGS: A cell microarray chip was used to detect for malaria-infected erythrocytes. The chip, with 20,944 microchambers (105 µm width and 50 µm depth), was made from polystyrene, and the formation of monolayers of erythrocytes in the microchambers was observed. Cultured Plasmodium falciparum strain 3D7 was used to examine the potential of the cell microarray chip for malaria diagnosis. An erythrocyte suspension in a nuclear staining dye, SYTO 59, was dispersed on the chip surface, followed by 10 min standing to allow the erythrocytes to settle down into the microchambers. About 130 erythrocytes were accommodated in each microchamber, there being over 2,700,000 erythrocytes in total on a chip. A microarray scanner was employed to detect any fluorescence-positive erythrocytes within 5 min, and 0.0001% parasitemia could be detected. To examine the contamination by leukocytes of purified erythrocytes from human blood, 20 µl of whole blood was mixed with 10 ml of RPMI 1640, and the mixture was passed through a leukocyte isolation filter. The eluted portion was centrifuged at 1,000×g for 2 min, and the pellet was dispersed in 1.0 ml of medium. SYTO 59 was added to the erythrocyte suspension, followed by analysis on a cell microarray chip. Similar accommodation of cells in the microchambers was observed. The number of contaminating leukocytes was less than 1 on a cell microarray chip. CONCLUSION: The potential of the cell microarray chip for the detection of malaria-infected erythrocytes was shown, it offering 10-100 times higher sensitivity than that of conventional light microscopy and easy operation in 15 min with purified erythrocytes

Detection Chip for Malaria

Background: Malaria is one of the major human infectious diseases in many endemic countries. For prevention of the spread of malaria, it is necessary to develop an early, sensitive, accurate and conventional diagnosis system. Methods and Findings: A cell microarray chip was used to detect for malaria-infected erythrocytes. The chip, with 20,944 microchambers (105 µm width and 50 µm depth), was made from polystyrene, and the formation of monolayers of erythrocytes in the microchambers was observed. Cultured Plasmodium falciparum strain 3D7 was used to examine the potential of the cell microarray chip for malaria diagnosis. An erythrocyte suspension in a nuclear staining dye, SYTO 59, was dispersed on the chip surface, followed by 10 min standing to allow the erythrocytes to settle down into the microchambers. About 130 erythrocytes were accommodated in each microchamber, there being over 2,700,000 erythrocytes in total on a chip. A microarray scanner was employed to detect any fluorescence-positive erythrocytes within 5 min, and 0.0001% parasitemia could be detected. To examine the contamination by leukocytes of purified erythrocytes from human blood, 20 µl of whole blood was mixed with 10 ml of RPMI 1640, and the mixture was passed through a leukocyte isolation filter. The eluted portion was centrifuged at 1,000×g for 2 min, and the pellet was dispersed in 1.0 ml of medium. SYTO 59 was added to the erythrocyte suspension, followed by analysis on a cell microarray chip. Similar accommodation of cells in the microchambers was observed. The number of contaminating leukocytes was less than 1 on a cell microarray chip. Conclusion: The potential of the cell microarray chip for the detection of malaria-infected erythrocytes was shown, it offering 10–100 times higher sensitivity than that of conventional light microscopy and easy operation in 15 min with purified erythrocytes

Experimental cerebral malaria progresses independently of the Nlrp3 inflammasome

Cerebral malaria is the most severe complication of Plasmodium falciparum infection in humans and the pathogenesis is still unclear. Using the P. berghei ANKA infection model of mice, we investigated a potential involvement of Nlrp3 and the inflammasome in the pathogenesis of cerebral malaria. Nlrp3 mRNA expression was upregulated in brain endothelial cells after exposure to P. berghei ANKA. Although Β-hematin, a synthetic compound of the parasites heme polymer hemozoin, induced the release of IL-1Β in macrophages through Nlrp3, we did not obtain evidence for a role of IL-1Β in vivo . Nlrp3 knock-out mice displayed a delayed onset of cerebral malaria; however, mice deficient in caspase-1, the adaptor protein ASC or the IL-1 receptor succumbed as WT mice. These results indicate that the role of Nlrp3 in experimental cerebral malaria is independent of the inflammasome and the IL-1 receptor pathway.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69193/1/764_ftp.pd

Lineage-specific positive selection at the merozoite surface protein 1 (msp1) locus of Plasmodium vivax and related simian malaria parasites

<p>Abstract</p> <p>Background</p> <p>The 200 kDa merozoite surface protein 1 (MSP-1) of malaria parasites, a strong vaccine candidate, plays a key role during erythrocyte invasion and is a target of host protective immune response. <it>Plasmodium vivax</it>, the most widespread human malaria parasite, is closely related to parasites that infect Asian Old World monkeys, and has been considered to have become a parasite of man by host switch from a macaque malaria parasite. Several Asian monkey parasites have a range of natural hosts. The same parasite species shows different disease manifestations among host species. This suggests that host immune responses to <it>P. vivax</it>-related malaria parasites greatly differ among host species (albeit other factors). It is thus tempting to invoke that a major immune target parasite protein such as MSP-1 underwent unique evolution, depending on parasite species that exhibit difference in host range and host specificity.</p> <p>Results</p> <p>We performed comparative phylogenetic and population genetic analyses of the gene encoding MSP-1 (<it>msp1</it>) from <it>P. vivax </it>and nine <it>P. vivax</it>-related simian malaria parasites. The inferred phylogenetic tree of <it>msp1 </it>significantly differed from that of the mitochondrial genome, with a striking displacement of <it>P. vivax </it>from a position close to <it>P. cynomolgi </it>in the mitochondrial genome tree to an outlier of Asian monkey parasites. Importantly, positive selection was inferred for two ancestral branches, one leading to <it>P. inui </it>and <it>P. hylobati </it>and the other leading to <it>P. vivax</it>, <it>P. fieldi </it>and <it>P. cynomolgi</it>. This ancestral positive selection was estimated to have occurred three to six million years ago, coinciding with the period of radiation of Asian macaques. Comparisons of <it>msp1 </it>polymorphisms between <it>P. vivax</it>, <it>P. inui </it>and <it>P. cynomolgi </it>revealed that while some positively selected amino acid sites or regions are shared by these parasites, amino acid changes greatly differ, suggesting that diversifying selection is acting species-specifically on <it>msp1</it>.</p> <p>Conclusions</p> <p>The present results indicate that the <it>msp1 </it>locus of <it>P. vivax </it>and related parasite species has lineage-specific unique evolutionary history with positive selection. <it>P. vivax </it>and related simian malaria parasites offer an interesting system toward understanding host species-dependent adaptive evolution of immune-target surface antigen genes such as <it>msp1</it>.</p

Toll-like receptor 9 mediates innate immune activation by the malaria pigment hemozoin

Malaria parasites within red blood cells digest host hemoglobin into a hydrophobic heme polymer, known as hemozoin (HZ), which is subsequently released into the blood stream and then captured by and concentrated in the reticulo-endothelial system. Accumulating evidence suggests that HZ is immunologically active, but the molecular mechanism(s) through which HZ modulates the innate immune system has not been elucidated. This work demonstrates that HZ purified from Plasmodium falciparum is a novel non-DNA ligand for Toll-like receptor (TLR)9. HZ activated innate immune responses in vivo and in vitro, resulting in the production of cytokines, chemokines, and up-regulation of costimulatory molecules. Such responses were severely impaired in TLR9−/− and myeloid differentiation factor 88 (MyD88)−/−, but not in TLR2, TLR4, TLR7, or Toll/interleukin 1 receptor domain–containing adaptor-inducing interferon β−/− mice. Synthetic HZ, which is free of the other contaminants, also activated innate immune responses in vivo in a TLR9-dependent manner. Chloroquine (CQ), an antimalarial drug, abrogated HZ-induced cytokine production. These data suggest that TLR9-mediated, MyD88-dependent, and CQ-sensitive innate immune activation by HZ may play an important role in malaria parasite–host interactions