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Burden of dengue infection and disease in a pediatric cohort in urban Sri Lanka.
Tissera, Hasitha,Amarasinghe, Ananda,De Silva, Aruna Dharshan,Kariyawasam, Pradeep,Corbett, Kizzmekia S,Katzelnick, Leah,Tam, Clarence,Letson, G William,Margolis, Harold S,de Silva, Aravinda M Allen Press, etc.] 2014 The American journal of tropical medicine and hygi Vol.91 No.1
<P>Dengue is the most significant arthropod-borne viral infection of humans. Persons infected with dengue viruses (DENV) have subclinical or clinically apparent infections ranging from undifferentiated fever to dengue hemorrhagic fever/shock syndrome. Although recent studies estimated that the Indian subcontinent has the greatest burden of DENV infection and disease worldwide, we do not have reliable, population-based estimates of the incidence of infection and disease in this region. The goal of this study was to follow-up a cohort of 800 children living in a heavily urbanized area of Colombo, Sri Lanka to obtain accurate estimates of the incidence of DENV infection and disease. Annual blood samples were obtained from all children to estimate dengue seroprevalence at enrollment and to identify children exposed to new DENV infections during the study year. Blood was also obtained from any child in whom fever developed over the course of the study year to identify clinically apparent DENV infections. At enrollment, dengue seroprevalence was 53.07%, which indicated high transmission in this population. Over the study year, the incidence of DENV infection and disease were 8.39 (95% confidence interval = 6.56-10.53) and 3.38 (95% confidence interval = 2.24-4.88), respectively, per 100 children per year. The ratio of clinically inapparent to apparent infections was 1.48. These results will be useful for obtaining more accurate estimates of the burden of dengue in the region and for making decisions about testing and introduction of vaccines.</P>
Characterization of East-Asian Helicobacter pylori encoding Western EPIYA-ABC CagA
Tissera Kavinda,Kim Myeong-A,Lai Jing,Angulmaduwa Sacheera,Kim Aeryun,Merrell D. Scott,김지혜,Su Hanfu,Cha Jeong-Heon 한국미생물학회 2022 The journal of microbiology Vol.60 No.2
The polymorphic bacterial oncoprotein, CagA shows geography- dependent variation in the C-terminal Glu-Pro-Ile- Tyr-Ala (EPIYA) motifs; East-Asian H. pylori isolates carry the ABD type while Western isolates carry the ABC type. In Western isolates, the EPIYA-C motif is sometimes found in multi-copy and this genotype is associated with disease severity. Interestingly, a small number of East-Asian H. pylori isolates have been found to carry Western ABC-type CagA. To gain a better understanding of these unusual isolates, the genomes of four Korean H. pylori clinical isolates carrying ABC-type CagA were sequenced via third generation (Pac- Bio SMRT) sequencing technology. The obtained data were utilized for phylogenetic analysis as well as comparison of additional virulence factors that are known to show geographic- dependent polymorphisms. Three of four isolates indeed belonged to the hpEastAsia group and showed typical East- Asian polymorphism in virulence factors such as homA/B/C, babA/B/C, and oipA. One isolate grouped to HpAfrica and showed typical Western polymorphism of virulence factors such as cagA, homA/B/C, and oipA. To understand the occurrence of the multi-copy EPIYA-C motif genotype in an East- Asian H. pylori background, the Korean clinical isolate, K154 was analyzed; this strain belonged to hpEastAsia but encoded CagA EPIYA-ABCCCC. Based on DNA sequence homology within the CagA multimerization (CM) sequence that flanked the EPIYA-C motifs, we predicted that the number of C motifs might change via homologous recombination. To test this hypothesis, K154 was cultured for one generation and 287 single colonies were analyzed for the number of EPIYA-C motifs using PCR-based screening and DNA sequencing verification. Three out of 284 (1%) single colony isolates showed changes in the number of EPIYA-C motifs in vitro; one isolate increased to five EPIYA-C motifs, one decreased to three EPIYA-C motifs, and one completely deleted the EPIYA-C motifs. The capacity for dynamic changes in the number of EPIYA-C repeats of CagA may play a role in generating important intraspecies diversity in East-Asian H. pylori.
Muditha Tissera,Ruvan Weerasinghe 한국정보통신학회 2022 Journal of information and communication convergen Vol.20 No.2
News in the form of web data generates increasingly large amounts of information as unstructured text. The capability of understanding the meaning of news is limited to humans; thus, it causes information overload. This hinders the effective use of embedded knowledge in such texts. Therefore, Automatic Knowledge Extraction (AKE) has now become an integral part of Semantic web and Natural Language Processing (NLP). Although recent literature shows that AKE has progressed, the results are still behind the expectations. This study proposes a method to auto-extract surface knowledge from English news into a machine-interpretable semantic format (triple). The proposed technique was designed using the grammatical structure of the sentence, and 11 original rules were discovered. The initial experiment extracted triples from the Sri Lankan news corpus, of which 83.5% were meaningful. The experiment was extended to the British Broadcasting Corporation (BBC) news dataset to prove its generic nature. This demonstrated a higher meaningful triple extraction rate of 92.6%. These results were validated using the inter-rater agreement method, which guaranteed the high reliability.
Brownian Motion Based Molecular Communication Network
P.S.S. Tissera,S. Choe 대한전자공학회 2015 ITC-CSCC :International Technical Conference on Ci Vol.2015 No.6
Quorum sensing (QS) is a bacterium-to-bacterium cell communication mechanism using signaling molecules called autoinducers (AI). We construct a point-to-point and a multiple access (MA) network using QS mechanism and analyze its capacity and bit-error-rate (BER) over 3- dimensional (3-D) Brownian-motion-based molecular communication (MC) channels.
Corbett, Kizzmekia S.,Katzelnick, Leah,Tissera, Hasitha,Amerasinghe, Ananda,de Silva, Aruna Dharshan,de Silva, Aravinda M. Oxford University Press 2015 The Journal of infectious diseases Vol.211 No.4
<P>Dengue viruses (DENVs) are mosquito-borne flaviviruses that infect humans. The clinical presentation of DENV infection ranges from inapparent infection to dengue hemorrhagic fever and dengue shock syndrome. We analyzed samples from a pediatric dengue cohort study in Sri Lanka to explore whether antibody responses differentiated clinically apparent infections from clinically inapparent infections. In DENV-naive individuals exposed to primary DENV infections, we observed no difference in the quantity or quality of acquired antibodies between inapparent and apparent infections. Children who experienced primary infections had broad, serotype–cross-neutralizing antibody responses that narrowed in breadth to a single serotype over a 12-month period after infection. In DENV immune children who were experiencing a repeat infection, we observed a strong association between preexisting neutralizing antibodies and clinical outcome. Notably, children with preexisting monospecific neutralizing antibody responses were more likely to develop fever than children with cross-neutralizing responses. Preexisting DENV neutralizing antibodies are correlated with protection from dengue disease.</P>
Su Hanfu,Bak Eun-Jung,Kim Aeryun,Tissera Kavinda,Cha Jeong-Heon,Jang Sungil 한국미생물학회 2022 The journal of microbiology Vol.60 No.8
Helicobacter pylori infection causes chronic inflammation in the stomach, which is linked to the development of gastric cancer. The anti-inflammatory and anticancer effects of a glycolysis inhibitor 2-deoxyglucose (2DG) and an antidiabetic medication metformin (Met) have gotten attention. Using a Mongolian gerbil animal model, we investigated H. pylorimediated gastric pathogenesis and how this pathogenesis is influenced by 2DG and Met. Five-week-old male gerbils were infected with H. pylori strain 7.13. After 2 weeks of infection, gerbils were fed 2DG-containing food (0.03% w/w), Met-containing water (0.5% w/v), or both (Combi) for 2 (short-term) or 10 weeks (long-term). Gastric pathogenesis and host response to H. pylori infection were examined by macroscopic and histopathologic analysis of gerbils’ stomach. As a result, indicators of gastric pathogenesis by H. pylori infection including infiltration of polymorphonuclear neutrophils and lymphocytes, intestinal metaplasia, atrophy, and proliferation of gastric epithelial cells were attenuated by short-term administration of 2DG, Met, or Combi. When the infection was sustained for long-term, gastric pathogenesis in drug-treated gerbils was equivalent to that in untreated gerbils, with the exception that the infiltration of neutrophil was reduced by 2DG. Colonization of H. pylori in stomach was unaffected by both short- and long-term treatments. Our findings demonstrate that the progression of gastric pathogenesis induced by H. pylori infection can be attenuated by the shortterm individual or combinational treatment of 2DG and Met, implying that 2DG or Met could be considered as a treatment option for gastric diseases in the early stages of infection.
Wernakulasooriya Manikkage Jayani Chethana Minoli Tissera,Suramya Indunil Rathnayake,Edirisinghe Dewage Nalaka Sandun Abeyrathne,남기창 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.13
Portunus pelagicus shell waste is highly accumulatedin seafood processing factories and has lowcommercial applications. The objective of this study was tomodify and develop a scale-up, simple, and high-yieldingchemical method for extraction and purification of chitinand chitosan from P. pelagicus shell waste. The developedmethod included a new ‘‘pretreatment’’ process usingacetic acid followed by chemical treatments at eachpurification step. The final product was characterized byXRD and FTIR spectroscopy. Control chitin and chitosanwere produced using a pre-described method for comparison. Yields of crude chitin, chitosan, and purified chitosanwere 32.52 ± 0.68%, 26.28 ± 0.47%, and 21.78 ± 0.34%respectively whereas in the control chitin and chitosan theyields were 20.34 ± 0.72% and 13.79 ± 0.93% respectively(p\0.05). Better physicochemical and functionalproperties were recorded in the developed method(p\0.05). Hence the developed methodology can bescaled up and used in industrial applications.