oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 1 )

2019 ( 182 )

2018 ( 210 )

2017 ( 232 )

Custom range...

Search Results: 1 - 10 of 205450 matches for " Nicholas P Day "
All listed articles are free for downloading (OA Articles)
Page 1 /205450
Display every page Item
The practicality and sustainability of a community advisory board at a large medical research unit on the Thai-Myanmar border  [PDF]
Khin Maung Lwin, Thomas J. Peto, Nicholas J. White, Nicholas P. J. Day, Francois Nosten, Michael Parker, Phaik Yeong Cheah
Health (Health) , 2013, DOI: 10.4236/health.2013.52031
Abstract:

Community engagement is increasingly promoted to strengthen the ethics of medical research in low-income countries. One strategy is to use community advisory boards (CABs): semi-independent groups that can potentially safeguard the rights of study participants and help improve research. However, there is little published on the experience of operating and sustaining CABs. The Shoklo Malaria Research Unit (SMRU) has been conducting research and providing healthcare in a population of refugees, migrant workers, and displaced people on the Thai-Myanmar border for over 25 years. In 2009 SMRU facilitated the establishment of the Tak Province Community Ethics Advisory Board (T-CAB) in an effort to formally engage with the local communities both to obtain advice and to establish a participatory framework within which studies and the provision of health care can take place. In this paper, we draw on our experience of community engagement in this unique setting, and on our interactions with the past and present CAB members to critically reflect upon the CAB’s goals, structure and operations with a focus on the practicalities, what worked, what did not, and on its future directions.

Plasmodium vivax Adherence to Placental Glycosaminoglycans
Kesinee Chotivanich, Rachanee Udomsangpetch, Rossarin Suwanarusk, Sasithon Pukrittayakamee, Polrat Wilairatana, James G. Beeson, Nicholas P. J. Day, Nicholas J. White
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034509
Abstract: Background Plasmodium vivax infections seldom kill directly but do cause indirect mortality by reducing birth weight and causing abortion. Cytoadherence and sequestration in the microvasculature are central to the pathogenesis of severe Plasmodium falciparum malaria, but the contribution of cytoadherence to pathology in other human malarias is less clear. Methodology The adherence properties of P. vivax infected red blood cells (PvIRBC) were evaluated under static and flow conditions. Principal Findings P. vivax isolates from 33 patients were studied. None adhered to immobilized CD36, ICAM-1, or thrombospondin, putative ligands for P. falciparum vascular cytoadherence, or umbilical vein endothelial cells, but all adhered to immobilized chondroitin sulphate A (CSA) and hyaluronic acid (HA), the receptors for adhesion of P. falciparum in the placenta. PvIRBC also adhered to fresh placental cells (N = 5). Pre-incubation with chondroitinase prevented PvIRBC adherence to CSA, and reduced binding to HA, whereas preincubation with hyaluronidase prevented adherence to HA, but did not reduce binding to CSA significantly. Pre-incubation of PvIRBC with soluble CSA and HA reduced binding to the immobilized receptors and prevented placental binding. PvIRBC adhesion was prevented by pre-incubation with trypsin, inhibited by heparin, and reduced by EGTA. Under laminar flow conditions the mean (SD) shear stress reducing maximum attachment by 50% was 0.06 (0.02) Pa but, having adhered, the PvIRBC could then resist detachment by stresses up to 5 Pa. At 37°C adherence began approximately 16 hours after red cell invasion with maximal adherence at 30 hours. At 39°C adherence began earlier and peaked at 24 hours. Significance Adherence of P. vivax-infected erythrocytes to glycosaminoglycans may contribute to the pathogenesis of vivax malaria and lead to intrauterine growth retardation.
Burkholderia pseudomallei Is Genetically Diverse in Agricultural Land in Northeast Thailand
Vanaporn Wuthiekanun,Direk Limmathurotsakul,Narisara Chantratita,Edward J. Feil,Nicholas P. J. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2009, DOI: 10.1371/journal.pntd.0000496
Abstract: Background The soil-dwelling Gram-negative bacterium Burkholderia pseudomallei is the cause of melioidosis. Extreme structuring of genotype and genotypic frequency has been demonstrated for B. pseudomallei in uncultivated land, but its distribution and genetic diversity in agricultural land where most human infections are probably acquired is not well defined. Methods Fixed-interval soil sampling was performed in a rice paddy in northeast Thailand in which 100 grams of soil was sampled at a depth of 30 cm from 10×10 sampling points each measuring 2.5 m by 2.5 m. Soil was cultured for the presence of B. pseudomallei and genotyping of colonies present on primary culture plates was performed using a combination of pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Principal Findings B. pseudomallei was cultured from 28/100 samples. Genotyping of 630 primary colonies drawn from 11 sampling points demonstrated 10 PFGE banding pattern types, which on MLST were resolved into 7 sequence types (ST). Overlap of genotypes was observed more often between sampling points that were closely positioned. Two sampling points contained mixed B. pseudomallei genotypes, each with a numerically dominant genotype and one or more additional genotypes present as minority populations. Conclusions Genetic diversity and structuring of B. pseudomallei exists despite the effects of flooding and the physical and chemical processes associated with farming. These findings form an important baseline for future studies of environmental B. pseudomallei.
Saturated Graphs of Prescribed Minimum Degree
A. Nicholas Day
Mathematics , 2014,
Abstract: A graph $G$ is $H$-saturated if it contains no copy of $H$ as a subgraph but the addition of any new edge to $G$ creates a copy of $H$. In this paper we are interested in the function sat$_{t}(n,p)$, defined to be the minimum number of edges that a $K_{p}$-saturated graph on $n$ vertices can have if it has minimum degree at least $t$. We prove that sat$_{t}(n,p) = tn - O(1)$, where the limit is taken as $n$ tends to infinity. This confirms a conjecture of Bollob\'as when $p = 3$. We also present constructions for graphs that give new upper bounds for sat$_{t}(n,p)$ and discuss an analogous problem for saturated hypergraphs.
Burkholderia pseudomallei Is Spatially Distributed in Soil in Northeast Thailand
Direk Limmathurotsakul ,Vanaporn Wuthiekanun,Narisara Chantratita,Gumphol Wongsuvan,Premjit Amornchai,Nicholas P. J. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000694
Abstract: Background Melioidosis is a frequently fatal infectious disease caused by the soil dwelling Gram-negative bacterium Burkholderia pseudomallei. Environmental sampling is important to identify geographical distribution of the organism and related risk of infection to humans and livestock. The aim of this study was to evaluate spatial distribution of B. pseudomallei in soil and consider the implications of this for soil sampling strategies. Methods and Findings A fixed-interval sampling strategy was used as the basis for detection and quantitation by culture of B. pseudomallei in soil in two environmental sites (disused land covered with low-lying scrub and rice field) in northeast Thailand. Semivariogram and indicator semivariogram were used to evaluate the distribution of B. pseudomallei and its relationship with range between sampling points. B. pseudomallei was present on culture of 80/100 sampling points taken from the disused land and 28/100 sampling points from the rice field. The median B. pseudomallei cfu/gram from positive sampling points was 378 and 700 for the disused land and the rice field, respectively (p = 0.17). Spatial autocorrelation of B. pseudomallei was present, in that samples taken from areas adjacent to sampling points that were culture positive (negative) for B. pseudomallei were also likely to be culture positive (negative), and samples taken from areas adjacent to sampling points with a high (low) B. pseudomallei count were also likely to yield a high (low) count. Ranges of spatial autocorrelation in quantitative B. pseudomallei count were 11.4 meters in the disused land and 7.6 meters in the rice field. Conclusions We discuss the implications of the uneven distribution of B. pseudomallei in soil for future environmental studies, and describe a range of established geostatistical sampling approaches that would be suitable for the study of B. pseudomallei that take account of our findings.
Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis
Siriphan Boonsilp, Janjira Thaipadungpanit, Premjit Amornchai, Vanaporn Wuthiekanun, Wirongrong Chierakul, Direk Limmathurotsakul, Nicholas P Day, Sharon J Peacock
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-338
Abstract: We evaluated our hypothesis during a prospective study of 418 consecutive patients presenting to a hospital in northeast Thailand with an acute febrile illness. Admission blood samples were taken for Leptospira culture and PCR. A single tube nested PCR that amplified a region of the rrs gene was developed and applied, amplicons sequenced and a phylogenetic tree reconstructed.39/418 (9%) patients were culture-positive for Leptospira spp., and 81/418 (19%) patients were culture-negative but rrs PCR-positive. The species associated with culture-positive leptospirosis (37 L. interrogans and 2 L. borgpetersenii) were comparable to those associated with culture-negative, PCR-positive leptospirosis (76 L. interrogans, 4 L. borgpetersenii, 1 unidentified, possibly new species).Molecular speciation failed to identify a unique bacterial subset in patients with culture-negative, PCR-positive leptospirosis. The rate of false-negative culture was high, and we speculate that antibiotic pre-treatment is the most likely explanation for this.Leptospirosis is an acute febrile illness caused by pathogenic species belonging to the genus Leptospira [1,2]. This zoonotic disease has a worldwide distribution but is most common in tropical and subtropical regions and has the greatest impact on public health in developing countries [1-4]. Disease is maintained by chronic carrier hosts that excrete the organism into the environment, and infection in man results from direct contact with infected animals or indirect contact with a contaminated environment [1-3].Leptospira are present in the blood during the first week of infective symptoms [1,2]. Culture is rarely performed in routine clinical practice since this may take several months and requires considerable expertise, which places it within the domain of specialist reference centres. Culture continues to have an important role, however, in defining the global epidemiology of infection [4]. Identification of the serovar of infecting isolate
Activities of Daily Living Associated with Acquisition of Melioidosis in Northeast Thailand: A Matched Case-Control Study
Direk Limmathurotsakul ,Manas Kanoksil,Vanaporn Wuthiekanun,Rungrueng Kitphati,Bianca deStavola,Nicholas P. J. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002072
Abstract: Background Melioidosis is a serious infectious disease caused by the Category B select agent and environmental saprophyte, Burkholderia pseudomallei. Most cases of naturally acquired infection are assumed to result from skin inoculation after exposure to soil or water. The aim of this study was to provide evidence for inoculation, inhalation and ingestion as routes of infection, and develop preventive guidelines based on this evidence. Methods/Principal Findings A prospective hospital-based 1:2 matched case-control study was conducted in Northeast Thailand. Cases were patients with culture-confirmed melioidosis, and controls were patients admitted with non-infectious conditions during the same period, matched for gender, age, and diabetes mellitus. Activities of daily living were recorded for the 30-day period before onset of symptoms, and home visits were performed to obtain drinking water and culture this for B. pseudomallei. Multivariable conditional logistic regression analysis based on 286 cases and 512 controls showed that activities associated with a risk of melioidosis included working in a rice field (conditional odds ratio [cOR] = 2.1; 95% confidence interval [CI] 1.4–3.3), other activities associated with exposure to soil or water (cOR = 1.4; 95%CI 0.8–2.6), an open wound (cOR = 2.0; 95%CI 1.2–3.3), eating food contaminated with soil or dust (cOR = 1.5; 95%CI 1.0–2.2), drinking untreated water (cOR = 1.7; 95%CI 1.1–2.6), outdoor exposure to rain (cOR = 2.1; 95%CI 1.4–3.2), water inhalation (cOR = 2.4; 95%CI 1.5–3.9), current smoking (cOR = 1.5; 95%CI 1.0–2.3) and steroid intake (cOR = 3.1; 95%CI 1.4–6.9). B. pseudomallei was detected in water source(s) consumed by 7% of cases and 3% of controls (cOR = 2.2; 95%CI 0.8–5.8). Conclusions/Significance We used these findings to develop the first evidence-based guidelines for the prevention of melioidosis. These are suitable for people in melioidosis-endemic areas, travelers and military personnel. Public health campaigns based on our recommendations are under development in Thailand.
Using a Web-Based Application to Define the Accuracy of Diagnostic Tests When the Gold Standard Is Imperfect
Cherry Lim, Prapass Wannapinij, Lisa White, Nicholas P. J. Day, Ben S. Cooper, Sharon J. Peacock, Direk Limmathurotsakul
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079489
Abstract: Background Estimates of the sensitivity and specificity for new diagnostic tests based on evaluation against a known gold standard are imprecise when the accuracy of the gold standard is imperfect. Bayesian latent class models (LCMs) can be helpful under these circumstances, but the necessary analysis requires expertise in computational programming. Here, we describe open-access web-based applications that allow non-experts to apply Bayesian LCMs to their own data sets via a user-friendly interface. Methods/Principal Findings Applications for Bayesian LCMs were constructed on a web server using R and WinBUGS programs. The models provided (http://mice.tropmedres.ac) include two Bayesian LCMs: the two-tests in two-population model (Hui and Walter model) and the three-tests in one-population model (Walter and Irwig model). Both models are available with simplified and advanced interfaces. In the former, all settings for Bayesian statistics are fixed as defaults. Users input their data set into a table provided on the webpage. Disease prevalence and accuracy of diagnostic tests are then estimated using the Bayesian LCM, and provided on the web page within a few minutes. With the advanced interfaces, experienced researchers can modify all settings in the models as needed. These settings include correlation among diagnostic test results and prior distributions for all unknown parameters. The web pages provide worked examples with both models using the original data sets presented by Hui and Walter in 1980, and by Walter and Irwig in 1988. We also illustrate the utility of the advanced interface using the Walter and Irwig model on a data set from a recent melioidosis study. The results obtained from the web-based applications were comparable to those published previously. Conclusions The newly developed web-based applications are open-access and provide an important new resource for researchers worldwide to evaluate new diagnostic tests.
The Diversity and Geographical Structure of Orientia tsutsugamushi Strains from Scrub Typhus Patients in Laos
Rattanaphone Phetsouvanh?,Piengchan Sonthayanon?,Sasithon Pukrittayakamee?,Daniel H. Paris?,Paul N. Newton?,Edward J. Feil?,Nicholas P. J. Day
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0004024
Abstract: Orientia tsutsugamushi is the causative agent of scrub typhus, a disease transmitted by Leptotrombidium mites which is responsible for a severe and under-reported public health burden throughout Southeast Asia. Here we use multilocus sequence typing (MLST) to characterize 74 clinical isolates from three geographic locations in the Lao PDR (Laos), and compare them with isolates described from Udon Thani, northeast Thailand. The data confirm high levels of diversity and recombination within the natural O. tsutsugamushi population, and a rate of mixed infection of ~8%. We compared the relationships and geographical structuring of the strains and populations using allele based approaches (eBURST), phylogenetic approaches, and by calculating F-statistics (FST). These analyses all point towards low levels of population differentiation between isolates from Vientiane and Udon Thani, cities which straddle the Mekong River which defines the Lao/Thai border, but with a very distinct population in Salavan, southern Laos. These data highlight how land use, as well as the movement of hosts and vectors, may impact on the epidemiology of zoonotic infections.
A High Burden of Respiratory Syncytial Virus Associated Pneumonia in Children Less than Two Years of Age in a South East Asian Refugee Population
Claudia Turner, Paul Turner, Verena Cararra, Naw Eh Lwe, Wanitda Watthanaworawit, Nicholas P. Day, Nicholas J. White, David Goldblatt, Fran?ois Nosten
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050100
Abstract: Background Pneumonia is a major cause of childhood mortality and morbidity approximately 1.6 million deaths and 150 million episodes occur annually in children <5 years. Respiratory syncytial virus (RSV) may be responsible for up to 25% of cases and 12% of deaths making it an important potential vaccine target, although data from South East Asia is scarce. Methods We followed a birth cohort of Burmese refugee children, born over a one year period, for two years. Pneumonia episodes were diagnosed using WHO criteria. A chest radiograph, nasopharyngeal aspirate and non-specific markers of infection were taken during each episode. Results The incidence of RSV-associated pneumonia was 0.24 (95% CI 0.22–0.26) episodes per child year. All children with pneumonia received antibiotic treatment, following WHO guidelines. The highest incidence was in the 2–12 month age group. The commonest diagnosis in a child with RSV-associated pneumonia was non-severe pneumonia (239/362:66.0%), however the incidence of RSV-associated severe or very severe pneumonia was 0.08 (95% CI 0.01–0.10) episodes per child year. Birth in the wet season increased the risk of severe disease in children who had their first episode of RSV-associated pneumonia aged 2–11 months (OR 28.7, 95% CI 6.6–125.0, p<0.001). RSV episodes were highly seasonal being responsible for 80.0% of all the pneumonia episodes occurring each October and November over the study period. Conclusions There was a high incidence of RSV associated pneumonia in this refugee population. Interventions to prevent RSV infection have the potential to reduce the incidence of clinically diagnosed pneumonia and hence unnecessary antibiotic usage in this population.
Page 1 /205450
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.