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Search Results: 1 - 10 of 1534 matches for " Grace Yap "
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Use of Saliva for Early Dengue Diagnosis
Grace Yap equal contributor,Bijon Kumar Sil equal contributor,Lee-Ching Ng
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001046
Abstract: Background The necessity of a venous blood collection in all dengue diagnostic assays and the high cost of tests that are available for testing during the viraemic period hinder early detection of dengue cases and thus could delay cluster management. This study reports the utility of saliva in an assay that detects dengue virus (DENV)–specific immunoglobulin A (Ig A) early in the phase of a dengue infection. Methods and Findings Using an antigen capture anti-DENV IgA (ACA) ELISA technique, we tested saliva samples collected from dengue-confirmed patients. The sensitivity within 3 days from fever onset was over 36% in primary dengue infections. The performance is markedly better in secondary infections, with 100% sensitivity reported in saliva samples from day 1 after fever onset. Serum and salivary IgA levels showed good correlation (Pearson's r = 0.69, p<0.001). Specificity was found to be 97%. Conclusion Our findings suggest that this technique would be very useful in dengue endemic regions, where the majority of dengue cases are secondary. The ACA-ELISA is easy to perform, cost effective, and especially useful in laboratories without sophisticated equipment. Our findings established the usefulness and reliability of saliva for early dengue diagnosis.
Epidemiological characteristics of the 2005 and 2007 dengue epidemics in Singapore - similarities and distinctions
Teck Siang Ler,Li Wei Ang,Grace Siew Lian Yap,Lee Ching Ng
Western Pacific Surveillance and Response , 2011,
Abstract: Introduction: We investigated the epidemiological features of the 2007 dengue outbreak to determine the factors that could have triggered it two years after the previous large outbreak in 2005.Methods: All laboratory-confirmed cases of dengue reported during the year, as well as entomological and virological data, were analysed.Results: A total of 8826 cases including 24 deaths were reported in 2007, giving an incidence of 192.3 cases per 100 000 residents and a case-fatality rate of 0.27%. The median age of the cases was 37 years (interquartile range 25 to 50), with an age range from two days to 101 years, which was higher than the median age of 31 years (interquartile range 20 to 42), with a range from four days to 98 years, in 2005. The overall Aedes premises index in 2007 was 0.68%, lower than the 1.15% observed in 2005. The predominant dengue serotype in 2007 was dengue virus DENV-2 which re-emerged with a clade replacement in early 2007, and overtook the predominant serotype (DENV-1) of 2005. Seroprevalence studies conducted in the three largest outbreak clusters revealed that 73.2% of residents with recent infection were asymptomatic.Discussion: With the exception of an increase in the median age of the cases, and a change in the predominant dengue serotype, the epidemiological features of the 2007 epidemic were largely similar to those of 2005. Singapore remains vulnerable to major outbreaks of dengue, despite sustained vector control measures to maintain a consistently low Aedes premises index.
Molecular Genetic Evidence for the Place of Origin of the Pacific Rat, Rattus exulans
Vicki Thomson, Ken P. Aplin, Alan Cooper, Susan Hisheh, Hitoshi Suzuki, Ibnu Maryanto, Grace Yap, Stephen C. Donnellan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091356
Abstract: Commensal plants and animals have long been used to track human migrations, with Rattus exulans (the Pacific rat) a common organism for reconstructing Polynesian dispersal in the Pacific. However, with no knowledge of the homeland of R. exulans, the place of origin of this human-commensal relationship is unknown. We conducted a mitochondrial DNA phylogeographic survey of R. exulans diversity across the potential natural range in mainland and Island Southeast Asia in order to establish the origin of this human-commensal dyad. We also conducted allozyme electrophoresis on samples from ISEA to obtain a perspective on patterns of genetic diversity in this critical region. Finally, we compared molecular genetic evidence with knowledge of prehistoric rodent faunas in mainland and ISEA. We find that ISEA populations of R. exulans contain the highest mtDNA lineage diversity including significant haplotype diversity not represented elsewhere in the species range. Within ISEA, the island of Flores in the Lesser Sunda group contains the highest diversity in ISEA (across all loci) and also has a deep fossil record of small mammals that appears to include R. exulans. Therefore, in addition to Flores harboring unusual diversity in the form of Homo floresiensis, dwarfed stegodons and giant rats, this island appears to be the homeland of R. exulans.
Evaluation of Chikungunya Diagnostic Assays: Differences in Sensitivity of Serology Assays in Two Independent Outbreaks
Grace Yap,Kwoon-Yong Pok,Yee-Ling Lai,Hapuarachchige-Chanditha Hapuarachchi,Angela Chow,Yee-Sin Leo,Li-Kiang Tan,Lee-Ching Ng
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000753
Abstract: Background The sensitivity and specificity of two in-house MAC-ELISA assays were tested and compared with the performance of commercially-available CTK lateral flow rapid test and EUROIMMUN IFA assays for the detection of anti-Chikungunya virus (CHIKV) IgM. Each MAC-ELISA assay used a whole virus-based antigen derived from genetically distinct CHIKV strains involved in two chikungunya disease outbreaks in Singapore (2008); a January outbreak strain with alanine at amino acid residue 226 of the E1 glycoprotein (CHIKV-A226) and a May-to-September outbreak strain that possessed valine at the same residue (CHIKV-226V). We report differences in IgM detection efficacy of different assays between the two outbreaks. The sensitivities of two PCR protocols were also tested. Methods and Findings For sera from January outbreak, the average detection threshold of CTK lateral flow test, MAC-ELISAs and EUROIMMUN IFA assays was 3.75, 4.38 and 4.88 days post fever onset respectively. In contrast, IgM detection using CTK lateral flow test was delayed to more than 7 days after fever onset in the second outbreak sera. However, MAC-ELISA using CHIKV-226V detected IgM in the second outbreak sera 3.96 days after fever onset, which was approximately one day earlier compared to the same assay using CHIKV-A226 (4.86 days). Specificity was 100% for both commercial assays, and 95.6% for the in-house MAC-ELISAs. For sensitivity determination of the PCR protocols, the probe-based real time RT-PCR method was found to be 10 times more sensitive than one based on SYBR Green. Conclusion Our findings suggested that the two strains of CHIKV using variants A226 and 226V resulted in variation in sensitivities of the assays evaluated. We postulated that the observed difference in antigen efficacy could be due to the amino acid substitution differences in viral E1 and E2 envelope proteins, especially the E1-A226V substitution. This evaluation demonstrates the importance of appraisal of different diagnostic assays before their application in clinical and operational settings.
Molecular characterization of two hantavirus strains from different rattus species in Singapore
Patrik Johansson, Grace Yap, Hwee-Teng Low, Chern-Chiang Siew, Relus Kek, Lee-Ching Ng, G?ran Bucht
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-15
Abstract: Pan-hanta RT-PCR performed on samples of Rattus norvegicus and Rattus tanezumi indicated that 27 (2.24%) of the animals were positive. sequence analysis of the S and M segments established that two different hantavirus strains circulate in the rodent population of Singapore. Notably, the hantavirus strains found in Rattus norvegicus clusters with other Asian Seoul virus sequences, while the virus strains found in Rattus tanezumi had the highest sequence similarity to the Serang virus from Rattus tanezumi in Indonesia, followed by Cambodian hantavirus isolates and the Thailand virus isolated from Bandicota indica.Sequence analysis of the S and M segments of hantavirus strains found in Rattus norvegicus (Seoul virus strain Singapore) and Rattus tanezumi (Serang virus strain Jurong TJK/06) revealed that two genetically different hantavirus strains were found in rodents of Singapore. Evidently, together with Serang, Cambodian and Thailand virus the Jurong virus forms a distinct phylogroup. Interestingly, these highly similar virus strains have been identified in different rodent hosts. Further studies are underway to analyze the public health significance of finding hantavirus strains in Singapore rodents.The hantavirus genus in the Bunyaviridae family contains several important human pathogens that are prevalent worldwide. This group of viruses includes the etiological agents of hemorrhagic fever with renal syndrome (HFRS), largely seen in Europe and Asia, and hantaviruses causing (cardio) pulmonary syndrome (HCPS) in the Americas. The clinical severity of hantavirus infections ranges from asymptomatic infections to fulminate hemorrhagic shock and death. Hantaan virus (HTNV) and Dobrava viruses (DOBV) are causative agents of severe forms of HFRS and mortality rates of up to 15% have been reported. About 20 - 30% of HTNV infected patients develop hemorrhages [1,2].Hantaviruses are enveloped and contain genomes composed of three negative-stranded RNA segments; small (S),
Potential good reduction of degree 2 rational maps
Diane Yap
Mathematics , 2012,
Abstract: We give a complete characterization of degree two rational maps with potential good reduction over local fields. We show this happens exactly when the map corresponds to an integral point in the moduli space. We detail an algorithm by which to conjugate any degree two rational map corresponding to an integral point in the moduli space into a map with unit resultant. The local fields result is used to solve the same problem for fields over a principal ideal domain. Some additional results are given for degree 2 rational maps over the rationals.
Does Reactive Adaptation Exist? Using the Ecosystem Service Governance Approach to Evaluate Post-Drought Rural Food Security in Kenya  [PDF]
Grace W. Ngaruiya
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.58037
Controversial climate change studies purport that predicted food insecurity and resource scarcity will intensify resource conflicts in developing nations. This belief is based on a prevalent assumption that African agricultural production systems are rigid and that their respective governments lack comprehensive adaptation ability. Therefore, I investigate whether and how effective post- drought adaptation activity is sustaining food production and livelihoods at Loitoktok district in Kenya. This study uses the theoretical three-step ecosystem service governance approach that analyzes both natural resources attributes and relational data. Results confirm a substantial decline in productivity and huge monetary losses in the agricultural sector of Loitoktok following the 2009 drought. Post-drought analysis reveals high diversification in crops and livestock that are drought-tolerant, fast maturing and high income generating such as camels, rabbits and dairy goats, horticultural and fruit production that sustain food security, income and local livelihoods. These reactive adaptation activities originate from an active public-private cooperation that promotes knowledge exchange among Loitoktok stakeholders. This cooperation is also seen in the efficient resource conflict resolution network. In conclusion, rural communities seem to be efficiently adapting to changing environmental conditions but require more financial and technical support from the government. Unfortunately, appraisal of national planned adaptation reveals effort-duplication that may divert much needed adaptation funds from being invested in research projects with multiple benefits to Kenyan food producers.
Testing the Effect of Soil Heterogeneity on Arbuscular Mycorrhiza Fungi (AMF) Contribution to Plant Productivity  [PDF]
Samuel Ayesu, Grace Gyabaah
Open Journal of Ecology (OJE) , 2014, DOI: 10.4236/oje.2014.46028

Most natural soils are heterogeneous and nutrient availability and soil structure change greatly over small distances. It is still unclear whether AMF are advantageous for plants under such heterogeneous soil conditions. The objective of this study was to determine whether diverse AMF community support host plant community productivity in heterogeneous soil. It was also tested whether soil heterogeneity affects plant productivity. This was carried out in a greenhouse experiment made up of two factors: soil heterogeneity and AMF richness. Soil heterogeneity was simulated by mixing three soil types (sand, field soil and organic soil) together (homogenous soil (HM)), mixing them partly (semi homogenous (SH)) or keeping the three soil types separate in three compartments within one pot (heterogeneous (HT)). AMF richness was simulated by adding no AMF, one of four different AMF species separately, or all four different AMF together. The pots were planted with a mixture of Trifolium pratense and Lolium multiflorum. There was no effect of soil heterogeneity on total plant biomass. However, the biomass of the individual plant species was greatly affected by soil heterogeneity with Lolium being the most abundant in the heterogeneous soil and Trifolium being the most abundant in the homogenous soil. Total plant biomass did not increase with AMF richness. Moreover, opposite to the hypothesis, AMF richness was not beneficial for plant productivity in a heterogenous soil environment. However, there were significant differences in plant biomass with different AMF treatments in the SH and HT treatment indicating that effects of AMF on plant productivity are influenced by soil type. These effects on yield and AMF reflect a combination of local responses to growing conditions. The results show that AMF influence on plant yield may not always be positive but is strongly dependent on ecological elasticity and environmental condition.

The Universality of the Portrayal of Gender in Television Advertisements: An East-West Comparison  [PDF]
Grace Lim, Adrian Furnham
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.713154
Abstract: This study compared portrayals of gender in Malaysian and British television advertisements regarding the portrayal of men and women across these two countries. A total of 236 advertisements were content analyzed for nine variables relating to the primary character of the advertisement. The findings provide evidence of gender stereotyping in both countries for types of products advertised, credibility and role of the primary characters. The results suggest that portrayals in British advertisements are similar to those in Malaysian advertisements despite the cultural gap. These findings are discussed in relation to implications and the limitations of the study are noted.
Virtues in Clinical Practice: Teaching Students about the Complexities and Depth of Professional Practice  [PDF]
Sandra Grace, Airdre Grant
Creative Education (CE) , 2017, DOI: 10.4236/ce.2017.813143
Abstract: This paper investigates the integration of virtues into teaching programs for allied health students. It explores the notion that practitioners’ effectiveness is enhanced when they practice virtues along with their technical expertise. These virtues include wisdom and love and they imbue the practitioner’s role with a meaning that extends beyond efficient diagnosis and competent case management. Practicing virtues can deepen the clinical relationship. Allied health students may feel cautious and uncertain about what it actually means to be a virtuous practitioner. Reflexive practice and dialogic encounters are presented as teaching activities that can cultivate virtuous practice.
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