Search

Accuracy of the InBios DENV Detect IgM, IgG and NS1 antigen (Ag) ELISAs (Seattle, WA) for detection of dengue virus (DENV) infection were evaluated using 100 retrospectively selected sera from acutely febrile patients presenting to a Singapore hospital. The InBios DENV NS1, IgM and IgG ELISAs had an overall sensitivity of 83.6%, 40% and 58.2% and an overall specificity of 97.8%, 97.8% and 55.6%, respectively. Simultaneous testing for NS1 and IgM-antibodies yielded a sensitivity and specificity of 85.5% and 95.5%, respectively, which did not significantly differ from testing for NS1 Ag alone. Using sera positive for IgM- or IgG-class antibodies to six common arboviruses, the InBios IgM and IgG ELISAs showed an overall analytic specificity of 89.2% and 66.4%, respectively. This study suggests that recent DENV infection can reliably be detected by the InBios NS1 Ag ELISA alone and that InBios DENV IgG reactivity should be interpreted with caution.

Summary The reemergence of Zika virus (ZIKV) warrants the need to develop complementary diagnostic measures. In this study, flow cytometry was used to determine the presence of ZIKV NS3 antigen in blood monocytes from ZIKV-infected patients, Background Epidemics caused by the reemergence of Zika virus (ZIKV) warrant the need to develop new diagnostic measures to complement currently used detection methods. In this study, we explored the detection of ZIKV antigen in a defined leukocyte subset from patients’ whole-blood specimens. Methods Whole-blood samples were obtained at the acute and early convalescent phases from ZIKV-infected patients during the Singapore outbreak in August–September 2016. Presence of ZIKV antigen was determined by flow cytometry staining for intracellular ZIKV NS3, using a ZIKV-specific polyclonal antibody. The presence of ZIKV antigen was determined in CD45+CD14+ monocytes. Results Data showed that ZIKV NS3 antigen could be detected in CD45+CD14+ monocytes. The levels of detection were further categorized into 3 groups: high (positivity among >40% of monocytes), moderate (positivity among 10%–40%), and low (positivity among

Summary Background Dengue is the commonest vector-borne infection worldwide. It is often associated with thrombocytopenia, and prophylactic platelet transfusion is widely used despite the dearth of robust evidence. We aimed to assess the efficacy and safety of prophylactic platelet transfusion in the prevention of bleeding in adults with dengue and thrombocytopenia. Methods We did an open-label, randomised, superiority trial in five hospitals in Singapore and Malaysia. We recruited patients aged at least 21 years who had laboratory-confirmed dengue (confirmed or probable) and thrombocytopenia (≤20 000 platelets per μL), without persistent mild bleeding or any severe bleeding. Patients were assigned (1:1), with randomly permuted block sizes of four or six and stratified by centre, to receive prophylactic platelet transfusion in addition to supportive care (transfusion group) or supportive care alone (control group). In the transfusion group, 4 units of pooled platelets were given each day when platelet count was 20 000 per μL or lower; supportive care consisted of bed rest, fluid therapy, and fever and pain medications. The primary endpoint was clinical bleeding (excluding petechiae) by study day 7 or hospital discharge (whichever was earlier), analysed by intention to treat. Safety outcomes were analysed according to the actual treatment received. This study was registered with ClinicalTrials.gov, number NCT01030211, and is completed. Findings Between April 29, 2010, and Dec 9, 2014, we randomly assigned 372 patients to the transfusion group (n=188) or the control group (n=184). The intention-to-treat analysis included 187 patients in the transfusion group (one patient was withdrawn immediately) and 182 in the control group (one was withdrawn immediately and one did not have confirmed or probable dengue). Clinical bleeding by day 7 or hospital discharge occurred in 40 (21%) patients in the transfusion group and 48 (26%) patients in the control group (risk difference −4·98% [95% CI −15·08 to 5·34]; relative risk 0·81 [95% CI 0·56 to 1·17]; p=0·16). 13 adverse events occurred in the transfusion group and two occurred in the control group (5·81% [–4·42 to 16·01]; 6·26 [1·43 to 27·34]; p=0·0064). Adverse events that were possibly, probably, or definitely related to transfusion included three cases of urticaria, one maculopapular rash, one pruritus, and one chest pain, as well as one case each of anaphylaxis, transfusion-related acute lung injury, and fluid overload that resulted in serious adverse events. No death was reported. Interpretation In adult patients with dengue and thrombocytopenia, prophylactic platelet transfusion was not superior to supportive care in preventing bleeding, and might be associated with adverse events. Funding National Medical Research Council, Singapore.

Understanding the host immune response during Zika virus (ZIKV) infection will provide valuable insights into ZIKV immunopathogenesis. In this study, characterization of cellular changes and immune mediators of ZIKV-infected patients was performed, allowing for the identification of key infection-associated markers., Background Since its unexpected reemergence, Zika virus (ZIKV) has caused numerous outbreaks globally. This study characterized the host immune responses during ZIKV infection. Methods Patient samples were collected longitudinally during the acute, convalescence and recovery phases of ZIKV infection over 6 months during the Singapore outbreak in late 2016. Plasma immune mediators were profiled via multiplex microbead assay, while changes in blood cell numbers were determined with immunophenotyping. Results Data showed the involvement of various immune mediators during acute ZIKV infection accompanied by a general reduction in blood cell numbers for all immune subsets except CD14+ monocytes. Importantly, viremic patients experiencing moderate symptoms had significantly higher quantities of interferon γ–induced protein 10, monocyte chemotactic protein 1, interleukin 1 receptor antagonist, interleukin 8, and placental growth factor 1, accompanied by reduced numbers of peripheral CD8+ T cells, CD4+ T cells, and double-negative T cells. Levels of T-cell associated mediators, including interferon γ–induced protein 10, interferon γ, and interleukin 10, were high in recovery phases of ZIKV infection, suggesting a functional role for T cells. The identification of different markers at specific disease phases emphasizes the dynamics of a balanced cytokine environment in disease progression. Conclusions This is the first comprehensive study that highlights specific cellular changes and immune signatures during ZIKV disease progression, and it provides valuable insights into ZIKV immunopathogenesis.

Background Dengue virus infection typically causes mild dengue fever, but, in severe cases, life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) occur. The pathophysiological hallmark of DHF and DSS is plasma leakage that leads to enhanced vascular permeability, likely due to a cytokine storm. Methods Ninety patients with dengue during 2010-2012 in Singapore were prospectively recruited and stratified according to their disease phase, primary and secondary infection status, and disease severity, measured by plasma leakage. Clinical parameters were recorded throughout the disease progression. The levels of various immune mediators were quantified using comprehensive multiplex microbead-based immunoassays for 46 immune mediators. Results Associations between clinical parameters and immune mediators were analyzed using various statistical methods. Potential immune markers, including interleukin 1 receptor antagonist, interferon γ-inducible protein 10, hepatocyte growth factor, soluble p75 tumor necrosis factor α receptor, vascular cell adhesion molecule 1, and matrix metalloproteinase 2, were significantly associated with significant plasma leakage. Secondary dengue virus infections were also shown to influence disease outcome in terms of disease severity. Conclusions This study identified several key markers for exacerbated dengue pathogenesis, notably plasma leakage. This will allow a better understanding of the molecular mechanisms of DHF and DSS in patients with dengue.

Background Previously, most dengue cases in Singapore were hospitalized despite low incidence of dengue hemorrhagic fever (DHF) or death. To minimize hospitalization, the Communicable Disease Centre at Tan Tock Seng Hospital (TTSH) in Singapore implemented new admission criteria which included clinical, laboratory, and DHF predictive parameters in 2007. Method All laboratory-confirmed dengue patients seen at TTSH during 2006–2008 were retrospectively reviewed for clinical data. Disease outcome and clinical parameters were compared over the 3 years. Results There was a 33.0% mean decrease in inpatients after the new criteria were implemented compared with the period before (p < 0.001). The proportion of inpatients with DHF increased significantly from 31.7% in 2006 to 34.4% in 2008 (p = 0.008); 68 DHF cases were managed safely on an outpatient basis after compared with none before implementation. DHF inpatients had more serious signs such as clinical fluid accumulation (15.5% vs 2.9% of outpatients), while most DHF outpatients had hypoproteinemia (92.7% vs 81.3% of inpatients). The eight intensive care unit admissions and five deaths during this time period all occurred among inpatients. The new criteria resulted in a median cost saving of US$1.4 million to patients in 2008. Conclusion The new dengue admission criteria were effective in sustainably reducing length of hospitalization, yielding considerable cost savings. A minority of DHF patients with mild symptoms recovered uneventfully through outpatient management.

Introduction: Traditionally a disease mainly affecting the pediatric population, dengue burden has increased significantly in recent decades and adults with severe disease may become more common. There is currently no effective anti-viral agent available for the treatment of dengue and supportive care is the mainstay of management.Areas covered: We present a review of current literature on dengue severity classification systems and the management of severe dengue in adults. In particular, emphasis was placed on organ impairment in dengue and management of elderly individuals with multiple medical problems.Expert commentary: There is an urgent need to search for an effective anti-viral agent to treat infected individuals. The commercial availability of a dengue vaccine in older children has provided optimism in reducing the disease burden but long term efficacy and safety are unknown. The results from phase III trials of two new candidate vaccines are eagerly awaited.

BackgroundAcute upper respiratory infections (AURI) are the leading causes of antibiotic prescribing in primary care although antibiotics are often not indicated.AimTo gain an understanding of the knowledge, attitudes, and practices (KAP) of GPs in Singapore and the associated latent factors to guide the implementation of an effective programme to reduce antibiotic use in primary care.Design and setting:An anonymous survey on the KAP of antibiotic use in AURI of GPs in Singapore.MethodKAP survey questionnaires were posted to all GPs from a database. To ascertain the latent factors affecting prescribing patterns, exploratory factor analysis was performed.ResultsAmong 427 responses, 351 (82.2%) were from GPs working in private practice. It was found that 58.4% of GPs in the private versus 72.4% of those in the public sector recognised that >80% of AURIs were caused by viruses (P = 0.02). The majority of GPs (353/427; 82.7%) felt that antibiotics were overprescribed in primary care. Significant factors associated with low antibiotic prescribing were good medical knowledge and clinical competency (adjusted odds ratio [aOR] 3.2, 95% confidence interval [CI] = 2.4 to 4.3), good clinical practice (aOR 2.7 [95% CI = 2.0 to 3.6]), availability of diagnostic tests (aOR 1.4 [95% CI = 1.1 to 1.8]), and desire to improve clinical practice (aOR 1.5 [95% CI = 1.2 to 1.9]). The conservative practice of giving antibiotics ‘to be on the safe side’ is significantly less likely to be associated with low antibiotic prescribing (aOR 0.7 [95% CI = 0.5 to 0.9]).ConclusionThis is the first KAP survey on antibiotic prescribing for AURI among GPs in Singapore. With the latent factors identified, future interventions should be directed at addressing these factors to reduce inappropriate antibiotic prescribing.

Background Thrombocytopenia is a hallmark of dengue infection, and bleeding is a dreaded complication of dengue fever. Prophylactic platelet transfusion has been used to prevent bleeding in the management of dengue fever, although the evidence for its benefit is lacking. In adult dengue patients with platelet count 50,000/mm3 and increasing length of hospitalization., Author Summary Thrombocytopenia is one of the most prominent clinical features in dengue infection. This may manifest clinically as bleeding, which carries significant morbidity and mortality. For many years, clinicians have given dengue patients platelet transfusion in a bid to increase their platelet counts to prevent hemorrhagic manifestations. However, this practice has not been proven to reduce the risk of bleeding in dengue. Conversely, transfusion of blood products may be detrimental to patients as it can carry risks of fluid overload, transmission of infectious diseases and transfusion reactions. In this study, the authors found that platelet transfusion in the absence of bleeding in adult dengue patients did not prevent bleeding. Instead, this practice is associated with a slower platelet recovery and increased length of hospitalisation. These findings may contribute to better clinical management of thrombocytopenia in dengue patients and limit the use of these precious blood products.

Background Understanding the interaction between Aedes vectors and dengue viruses (DENV) has significant implications in determining the transmission dynamics of dengue. The absence of an animal model and ethical concerns regarding direct feeding of mosquitoes on patients has resulted in most infection studies using blood meals spiked with laboratory-cultured DENV. Data obtained from such studies may not reflect the natural human-mosquito transmission scenario. This study explored the potential of using membrane feeding of dengue patient’s blood as a substitute for direct skin feeding. Methods Four to six-day old female Ae. aegypti were provided the opportunity to feed via direct exposure to a patient’s forearm for 15 min or via exposure to EDTA-treated blood from the same patient through an artificial membrane for 30 min. Mosquitoes from both feeding methods were incubated inside environmental chambers. Mosquitoes were sampled at day 13 post-feeding. Midgut and salivary glands of each mosquito were dissected to determine DENV infection by RT-qPCR and viral titration, respectively. Results Feeding rates: Direct skin feeding assay (DSFA) consistently showed higher mosquito feeding rates (93.3–100 %) when compared with the membrane feeding assay (MFA) (48–98.2 %). Midgut infection: Pair-wise comparison between methods showed no significant difference in midgut infection rates between mosquitoes exposed via each method and a strong correlation was observed in midgut infection rates for both feeding methods (r = 0.89, P

Introduction: The incidence of newly diagnosed older patients diagnosed with human immunodeficiency virus (HIV) has increased worldwide in recent years. In this study, we compared the demographics and clinical presentation of younger and older patients in our HIV sentinel cohort. Materials and Methods: Among all HIV patients presenting to the Communicable Disease Centre (CDC), Singapore from 2006 to 2011, 793 were randomly included in our cohort, representing about 50% of the patients seen during that period. We collected demographic, clinical, laboratory, and outcome data from patient records to compare younger (

Introduction: Dengue fever remains a significant public health concern in Singapore. Appropriate, timely diagnosis and risk stratification for severe disease are crucial in the optimal management of this illness. In the outpatient setting, the primary care physician plays a key role in dengue diagnosis, management, and triage. We present a descriptive analysis of the variations in dengue knowledge, attitudes, and practices among primary care physicians (PCPs) in Singapore. Materials and Methods: A survey of 25 multiple-choice questions was mailed to 2000 PCPs in Singapore. Responses were analysed by physician age group (21-40, 41-60, and >61) and practice setting (government subsidised polyclinic or private practice). Results: Of the 3 questions assessing dengue knowledge, 89.9% chose 2 or 3 of the preferred responses. Half of the respondents utilised dengue diagnostic tests at least 50% of the time, and 75% used serology when doing so. Older respondents and those from private practices used diagnostic tests more often than their counterparts, and both groups favoured non-serology tests. About 85% of surveyed PCPs monitored confirmed or suspected cases daily, and one-third referred patients to a hospital always or often. Conclusions: While no major gaps in knowledge about dengue were identified in PCPs in Singapore, there were significant variations in clinical practice by physician age group and practice setting. The results of this survey provide a useful opportunity to identify strengths and areas in need of improved awareness in primary care management of dengue. Key words: Arbovirus, Guidelines, General practice, Ambulatory care

Background Methicillin-resistant Staphylococcus aureus (MRSA) poses an increasingly large disease and economic burden worldwide. The effectiveness of screening programs in the tropics is poorly understood. The aims of this study are: (i) to analyze the factors affecting MRSA colonization at admission and acquisition during hospitalization and (ii) to evaluate the cost-effectiveness of a screening program which aims to control MRSA incidence during hospitalization. Methods We conducted a retrospective case–control study of patients admitted to the Communicable Disease Centre (CDC) in Singapore between Jan 2009 and Dec 2010 when there was an ongoing selective screening and isolation program. Risk factors contributing to MRSA colonization on admission and acquisition during hospital stay were evaluated using a logistic regression model. In addition, a cost-effectiveness analysis was conducted to determine the cost per disability-adjusted life year (DALY) averted due to implementing the screening and isolation program. Results The average prevalence rate of screened patients at admission and the average acquisition rate at discharge during the study period were 12.1 and 4.8 % respectively. Logistic regression models showed that older age (adjusted odds ratio (OR) 1.03, 95 % CI 1.02–1.04, p

The exact mechanisms of interplay between host and viral factors leading to severe dengue are yet to be fully understood. Even though previous studies have implicated specific genetic differences of Dengue virus (DENV) in clinical severity and virus attenuation, similar studies with large-scale, whole genome screening of monophyletic virus populations are limited. Therefore, in the present study, we compared 89 whole genomes of DENV-2 cosmopolitan clade III isolates obtained from patients diagnosed with dengue fever (DF, n = 58), dengue hemorrhagic fever (DHF, n = 30) and dengue shock syndrome (DSS, n = 1) in Singapore between July 2010 and January 2013, in order to determine the correlation of observed viral genetic differences with clinical outcomes. Our findings showed no significant difference between the number of primary and secondary infections that progressed to DHF and DSS (p>0.05) in our study cohort. Despite being highly homogenous, study isolates possessed 39 amino acid substitutions of which 10 substitutions were fixed in three main groups of virus isolates. None of those substitutions were specifically associated with DHF and DSS. Notably, two evolutionarily unique virus groups possessing C-P43T+NS1-S103T+NS2A-V83I+NS3-R337K+ NS3-I600T+ NS5-P136S and NS2A-T119N mutations were exclusively found in patients with DF, the benign form of DENV infections. Those mutants were significantly associated with mild disease outcome. These observations indicated that disease progression into DHF and DSS within our patient population was more likely to be due to host than virus factors. We hypothesize that selection for potentially less virulent groups of DENV-2 in our study cohort may be an evolutionary adaptation of viral strains to extend their survival in the human-mosquito transmission cycle.

The ERK5 mitogen-activated protein kinase (MAPK) differs from other MAPKs in possessing a potent transcriptional activation domain. ERK5−/− embryos die from angiogenic defects, but the precise physiological role of ERK5 remains poorly understood. To elucidate molecular functions of ERK5 in the development of vasculature and other tissues, we performed gene profile analyses of erk5−/− mouse embryos and erk5−/− fibroblast cells reconstituted with ERK5 or ERK5(1-740), which lacks the transactivation domain. These experiments revealed several potential ERK5 target genes, including a proapoptotic gene bnip3, known angiogenic genes flt1 and lklf (lung Krüppel-like factor), and genes that regulate cardiovascular development. Among these, LKLF, known for its roles in angiogenesis, T-cell quiescence, and survival, was found to be absolutely dependent on ERK5 for expression in endothelial and T cells. We show that ERK5 drives lklf transcription by activating MEF2 transcription factors. Expression of erk5 short hairpin or a dominant-negative form of the ERK5 upstream activator, MEK5, in T cells led to downregulation of LKLF, increased cell size and upregulation of activation markers. Thus, through its kinase and transcriptional activation domains, ERK5 regulates transcriptional responses of cell survival and quiescence critical for angiogenesis and T-cell function.

Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial pathogen that has become increasingly prominent in hospitals and the community. HIV-positive patients may be one of the most MRSA-susceptible populations because of their immunocompromised status. At the Communicable Disease Centre, Tan Tock Seng Hospital, Singapore, we implemented a universal MRSA screening program and performed a case-control study to identify risk factors for MRSA colonization among 294 HIV patients at admission from January 2009 to January 2010. Among 54 HIV-positive patients who were MRSA positive at hospital admission, 16 (29.6%) were positive at the nares/axilla/groin (NAG; one combined swab), 14 (25.9%) were NAG and perianal positive, 3 (5.6%) were NAG and throat positive, 10 (18.5%) were NAG, perianal, and throat positive, 6 (11.1%) were throat positive, and 5 (9.3%) were perianal positive. Upon multivariate analysis, we found that age [odds ratio (OR)=1.04, 95% confidence interval (CI): 1.01-1.07, p=0.006] and CD4 count

Linear guideway systems of CNC machine tools are replacing the conventional slideways to achieve higher machining speed which has resulted in lower damping capacity. Damping carriages made of steel have been introduced to improve damping, however, that did not render significant improvement. Consequently, an attempt has been made in this study to improve damping in a CNC machine table by replacing the current steel damping carriage with one made of concrete since it has much higher internal damping. To select a suitable material for the carriage, the damping characteristics and strength of normal concrete, cellular concrete and polymer impregnated normal and cellular concrete have been investigated. It has been found that polymer impregnated cellular concrete (PC) is the most suitable material for the purpose. Consequently, a new damping carriage has been designed and fabricated using PC and has been incorporated into the table of a CNC machine table. This damping carriage has been found to improve the damping capacity and dynamic characteristics of the CNC table system equivalent of the slideway system.

The incidence of newly diagnosed older patients diagnosed with human immunodeficiency virus (HIV) has increased worldwide in recent years. In this study, we compared the demographics and clinical presentation of younger and older patients in our HIV sentinel cohort.Among all HIV patients presenting to the Communicable Disease Centre (CDC), Singapore from 2006 to 2011, 793 were randomly included in our cohort, representing about 50% of the patients seen during that period. We collected demographic, clinical, laboratory, and outcome data from patient records to compare younger (50 years old) and older (≥50 years old) HIV patients.Older patients comprised 27.1% of our HIV cohort and presented with lower median CD4 T cell counts (65 cells/mm³, interquartile range [IQR]: 27 to 214 cells/mm³) compared to younger patients (250 cells/mm³, IQR: 74 to 400 cells/mm³; P0.001). The median time from HIV diagnosis to initiation of antiretroviral therapy (ART) differed significantly for both age groups as well (49 days for patients50 years old, IQR: 18 to 294 days; versus 35 days for patients ≥50 years old, IQR: 14 to 102 days; P = 0.008). More of our younger patients were single (72.2%) or homosexual (44.1%), in contrast to older patients, of whom 48.8% were married and 84.7% were heterosexual.Upon comparison of our younger and older patients, we identified distinct differences in risk transmission and clinical presentation. Increased awareness of older patients at risk of HIV may improve time to diagnosis among this age group.

Dengue fever remains a significant public health concern in Singapore. Appropriate, timely diagnosis and risk stratification for severe disease are crucial in the optimal management of this illness. In the outpatient setting, the primary care physician plays a key role in dengue diagnosis, management, and triage. We present a descriptive analysis of the variations in dengue knowledge, attitudes, and practices among primary care physicians (PCPs) in Singapore.A survey of 25 multiple-choice questions was mailed to 2000 PCPs in Singapore. Responses were analysed by physician age group (21-40, 41-60, and61) and practice setting (government subsidised polyclinic or private practice).Of the 3 questions assessing dengue knowledge, 89.9% chose 2 or 3 of the preferred responses. Half of the respondents utilised dengue diagnostic tests at least 50% of the time, and 75% used serology when doing so. Older respondents and those from private practices used diagnostic tests more often than their counterparts, and both groups favoured non-serology tests. About 85% of surveyed PCPs monitored confirmed or suspected cases daily, and one-third referred patients to a hospital always or often.While no major gaps in knowledge about dengue were identified in PCPs in Singapore, there were significant variations in clinical practice by physician age group and practice setting. The results of this survey provide a useful opportunity to identify strengths and areas in need of improved awareness in primary care management of dengue.

cline during the 1980s of Connecticut farms and dairy and harvested crop production. These declines were somewhat offset in some areas by increases in agricultural activity in greenhouse, nursery, turf, and other speciality and nontraditional agricultural activities. For example, from 1982 to 1987 the value of nursery and greenhouse crops in Connecticut increased by 91% (Census of Agriculture). However, these are production areas where agricultural economics departments have traditionally had little expertise. Similar trends in other parts of the region combined to leave many agricultural economics departments struggling to redefine their role in the face of declining employment opportunities for students on farms and in the regional agribusiness sector. The experience of Connecticut and other Northeastern states in the 1980s has relevance

Background Dengue illness causes 50–100 million infections worldwide and threatens 2.5 billion people in the tropical and subtropical regions. Little is known about the disease burden and economic impact of dengue in higher resourced countries or the cost-effectiveness of potential dengue vaccines in such settings. Methods and Findings We estimate the direct and indirect costs of dengue from hospitalized and ambulatory cases in Singapore. We consider inter alia the impacts of dengue on the economy using the human-capital and the friction cost methods. Disease burden was estimated using disability-adjusted life years (DALYs) and the cost-effectiveness of a potential vaccine program was evaluated. The average economic impact of dengue illness in Singapore from 2000 to 2009 in constant 2010 US$ ranged between $0.85 billion and $1.15 billion, of which control costs constitute 42%–59%. Using empirically derived disability weights, we estimated an annual average disease burden of 9–14 DALYs per 100 000 habitants, making it comparable to diseases such as hepatitis B or syphilis. The proportion of symptomatic dengue cases detected by the national surveillance system was estimated to be low, and to decrease with age. Under population projections by the United Nations, the price per dose threshold for which vaccines stop being more cost-effective than the current vector control program ranged from $50 for mass vaccination requiring 3 doses and only conferring 10 years of immunity to $300 for vaccination requiring 2 doses and conferring lifetime immunity. The thresholds for these vaccine programs to not be cost-effective for Singapore were $100 and $500 per dose respectively. Conclusions Dengue illness presents a serious economic and disease burden in Singapore. Dengue vaccines are expected to be cost-effective if reasonably low prices are adopted and will help to reduce the economic and disease burden of dengue in Singapore substantially., Author Summary Dengue illness is a tropical disease transmitted by mosquitoes that threatens more than one third of the worldwide population. Dengue has important economic consequences because of the burden to hospitals, work absenteeism and risk of death of symptomatic cases. Governments attempt to reduce the disease burden using costly mosquito control strategies such as habitat reduction and spraying insecticide. Despite such efforts, the number of cases remains high. Dengue vaccines are expected to be available in the near future and there is an urgent need to evaluate their cost-effectiveness, i.e. whether their cost will be justified by the reduction in disease burden they bring. For such an evaluation, we estimated the economic impacts of dengue in Singapore and the expected vaccine costs for different prices. In this way we estimated price thresholds for which vaccination is not cost-effective. This research provides useful estimates that will contribute to informed decisions regarding the adoption of dengue vaccination programs.

Measuring the ex post losses from environmental quality change is an important issue when environmental contamination creates health risks, liability is assigned, and private compensation efforts are required. This paper proposes a methodology for measuring the ex post welfare impact of environmental quality change using market behavior from defensive expenditures. Conditions under which a defensive technology can provide a bound on welfare estimates are identified.

Adoption of agricultural practices that reduce or eliminate chemical use creates tradeoffs among yields and output, production costs and net income at the farm level. If widespread adoption is to occur, potential improvements in human health and the environment from reduced chemical use must be weighed against effects on aggregate farm income and consumer food prices. At present, these tradeoffs are subject to considerable debate.I review available farm level and aggregate economic studies of reductions in total agricultural chemical use. At the farm level, available studies suggest that organic and low-input farming systems result in declines in per acre yields and in lower net returns than most conventional farming systems, although the studies do indicate that net returns for the two systems can be comparable under some conditions. Several studies suggest that low-input systems perform well with respect to risk criteria. I also discuss the potential influence of government programs on the profitability of some low-input farming systems.All aggregate economic models conclude that widespread adoption of organic farming would result in decreased yields, decreased aggregate output, increased farm income, and large increases in consumer prices. These models have limitations, however. Recommendations are made for further economic research of the impacts of reducing agricultural chemical use at both the farm and aggregate levels.

Ventral tegmental area (VTA) stimulation produced conditioned place preferences for stimulation-paired environments the magnitudes of which were dose-dependently reduced by systemic application of the dopamine antagonist, haloperidol (0.0, 0.15, 0.3 mg/kg). Bilateral microinjections of cis-flupenthixol (FLU) into the nucleus accumbens (0.0, 1.0, 5.0 or 10.0 micrograms) also resulted in reductions in the size of stimulation-induced place preferences as well as reductions in the magnitude of the hyperlocomotor response to 1.5 mg/kg (s.c.) D-amphetamine. Comparable microinjections of FLU into the medial prefrontal cortex (PFC) produced diametrically opposite effects: the size of VTA stimulation-induced place preferences was either unaffected (1.0 and 5.0 microgram groups) or slightly increased (10 micrograms group) and amphetamine-stimulated hyperlocomotion was dose-dependently potentiated. These behavioral findings suggest a dopamine-mediated modulatory role for the PFC over reward relevant elements within the nucleus accumbens.

Background/methods To better understand dengue fever in the elderly, we compared clinical features, World Health Organization (WHO) dengue classification and outcomes between adult (, Author Summary Dengue is a neglected tropical disease that is increasingly affecting elderly patients; however, there is a paucity of data on clinical presentation and outcomes in this group. The limited data suggests that elderly dengue patients have the highest case-fatality rate but the pathogenesis of mortality in elderly dengue patients remains unclear. To better understand dengue fever in the elderly we compared clinical features, WHO dengue classification and outcomes between adult (

Background Elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) is prominent in acute dengue illness. The World Health Organization (WHO) 2009 dengue guidelines defined AST or ALT≥1000 units/liter (U/L) as a criterion for severe dengue. We aimed to assess the clinical relevance and discriminatory value of AST or ALT for dengue hemorrhagic fever (DHF) and severe dengue. Methodology/Principal Findings We retrospectively studied and classified polymerase chain reaction positive dengue patients from 2006 to 2008 treated at Tan Tock Seng Hospital, Singapore according to WHO 1997 and 2009 criteria for dengue severity. Of 690 dengue patients, 31% had DHF and 24% severe dengue. Elevated AST and ALT occurred in 86% and 46%, respectively. Seven had AST or ALT≥1000 U/L. None had acute liver failure but one patient died. Median AST and ALT values were significantly higher with increasing dengue severity by both WHO 1997 and 2009 criteria. However, they were poorly discriminatory between non-severe and severe dengue (e.g., AST area under the receiver operating characteristic [ROC] curve = 0.62; 95% confidence interval [CI]: 0.57–0.67) and between dengue fever (DF) and DHF (AST area under the ROC curve = 0.56; 95% CI: 0.52–0.61). There was significant overlap in AST and ALT values among patients with dengue with or without warning signs and severe dengue, and between those with DF and DHF. Conclusions Although aminotransferase levels increased in conjunction with dengue severity, AST or ALT values did not discriminate between DF and DHF or non-severe and severe dengue., Author Summary Dengue is a global public health problem, as the incidence of the disease has reached hyperendemic proportions in recent decades. Infection with dengue can cause acute, febrile illness or severe disease, which can lead to plasma leakage, bleeding, and organ impairment. One of the most prominent clinical characteristics of dengue patients is increased aspartate and alanine aminotransferase liver enzyme levels. The significance of this is uncertain, as it is transient in the majority of cases, and most patients recover uneventfully without liver damage. In this study, we characterized this phenomenon in the context of dengue severity and found that, although liver enzyme levels increased concurrently with dengue severity, they could not sufficiently discriminate between dengue fever and dengue hemorrhagic fever or between non-severe and severe dengue. Therefore clinicians may need to use other parameters to distinguish dengue severity in patients during early illness.

PURPOSE. To test the effects of subconjunctival topotecan (TPT) in fibrin sealant (FS) in transgenic murine retinoblastoma (RB). METHODS. Growth inhibitory, apoptotic, and cell cycle effects of TPT were assayed in human RB cell lines. In a dose-escalation study, eight groups of three 10- to 14-week-old wild-type mice were treated bilaterally with a single 30-L injection of subconjunctival TPT in FS (0.025, 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, or 3.2 mg/mL). Two groups of twenty 10-week-old LH-Tag transgenic mice were then treated in the right eye only with TPT in FS (3.2 mg/mL in 30 L; 0.1-mg total dose) or with FS only. The contralateral eye in each group was left untreated to serve as an internal control. After 3 weeks, ocular tumor burden was determined by histologic examination. RESULTS. At 48 hours, IC50 values of TPT in Y79 and Weri-Rb1 RB cell lines were 35 nM and 50 nM, respectively. Growth inhibitory effects were correlated with increased apoptosis and accumulation of cells in G2. Cytotoxicity of TPT was comparable in aqueous media and in FS. In the dose-escalation study, no histopathologic evidence of ocular toxicity was observed at any dose. Clinical toxicities (mild enophthalmos and eyelid alopecia) were observed only at the highest dose tested (3.2 mg/mL). In the treatment study, both eyes of TPT-treated mice demonstrated significant reduction in tumor burden compared with both eyes of mice treated with FS only (59% reduction; P 0.04). In mice treated with TPT, tumor burden in TPTtreated eyes and in untreated contralateral eyes did not differ significantly. CONCLUSIONS. Subconjunctival administration of TPT in FS to one eye allows the formation of a TPT depot sufficient for an effect to occur 3 weeks after treatment. This effect—bilateral reduction in tumor burden without a significant difference in treated versus untreated eyes—suggests that the major route of drug delivery in this system is hematogenous rather than transscleral. (Invest Ophthalmol Vis Sci. 2008;49:490‐496)

In response to public concerns, economists and other scientists have conducted research on agricultural chemicals and groundwater quality since the 1980s. The results of twenty-one studies conducted in various regions of the U.S. that examine the relationships between agrichemical treatments on crops, farm income, and groundwater quality both at the farm level and at the aggregate level are reviewed. Analysis of these studies indicates that across most regions, chemicals, and types of farms there is a trade-off between farm income and increased groundwater quality. In some situations, marginal improvements in groundwater quality can be achieved with limited reductions or even modest increases in farm income. However, most studies indicate that as reductions in agricultural chemical leaching to groundwater increase, reductions in farm income increase as well. Some issues for consideration in future research and extension projects in this arena are presented.

Full-owner operators and landowners with small holdings have lower minimum tillage adoption rates on cultivated cropland than do other landownership groups after accounting for land quality and regional location. Nonfamily corporate structure does not significantly influence the adoption decision. These conclusions about minimum tillage adoption were obtained from a logit model using 7,649 cultivated cropland observations from across the United States. This study indicates that small operating size poses more of an obstacle to minimum tillage adoption than does separation of ownership from farm operation.

Although soil erosion has been a recognized problem in the United States since the 1930s, recent soil losses have generated additional concern. This concern has been prompted by reports that soil erosion losses are increasing, thus intensifying air and water pollution problems and reducing the productivity potential of cropland. These reports accompany evidence that suggests further productivity increases from fertilizers, seed technologies, energy, and pesticides are uncertain (Crosson). These productivity trends, coupled with irreversible losses of agricultural land to urban and other uses and the possibility of increased demands for U.S. agricultural products, make the issue of conserving soil quality increasingly important.

The Committee on Opportunities for and Status of Women in Agricultural Economics was established by the Executive Board of the American Agricultural Economics Association in July 1980. The charge to the committee was "to ascertain the opportunities, role, and status of women in agricultural economics."1 Two important determinants of status within the profession are rank and salary. The objectives of this paper are, first, to develop a profile of women within the agricultural economics profession. The distribution of female agricultural economists by type ofjob, level of education, and among academics, tenure status, is analyzed along with data on salaries, experience, and research productivity. Second, the relative rank of women within the profession is explored by comparing profile data of male and female AAEA members. Finally, a model is developed to determine if significant salary differentials exist between men and women of comparable rank. Conclusions about the current status of women in agricultural economics are presented.

The results of the 1981 survey conducted by the Committee on Opportunities for and Status of Women in Agricultural Economics indicated that men and women within the profession differ with respect to type of employment, level of education, years of experience, and academic background (Lundeen and Clauson, Redman 1981, Lee, Lane). The studies presented by committee members at the 1981 annual meeting determined that proportionately fewer women than men are employed in academic jobs, have Ph.D. degrees, or majored in agricultural economics as undergraduates. Women also average approximately half the years of experience accumulated by men in the profession. These differences are reflected in the rank and salary of female agricultural economists. A lower proportion of women than men in academic jobs have tenure. Furthermore, significant salary differentials between male and female American Agricultural Economics Association (AAEA) members were found to exist even after accounting for education, experience, and other variables hypothesized to be determinants of salary. AAEA membership data developed since the 1981 survey provide additional information on men and women in

The comment by Heimlich correctly interprets the definition of the dependent variable, minimum tillage, in our analysis. The term minimum tillage did include the union of minimum tillage and residue management. The abbreviation to minimum tillage may have confused some readers. We appreciate the opportunity to clarify the definition. However, the objection raised by Heimlich to this definition of the dependent variable is, in our opinion, without merit. The comment critiques 1977 data, collected under 1977 guidelines, with standards developed much later. The SCS 1977 National Resources Inventory (NRI) asked district conservationists to list conservation practices in effect in a given field. Residue management, including stubble mulching, and minimum tillage, including no-till, were two separate practices on the list they were to choose from. No national SCS definition for minimum tillage was available at that time. Instead, each state individually defined the practice. Residue management in 1977 included stubble mulching, although in the more recent SCS proposals stubble mulching is considered part of a conservation tillage system. Because the delineations between the two practices in the 1977 NRI were fuzzy, particularly with respect to stubble mulching, we analyzed the occurrence of minimum tillage or residue management. As the comment author indicates, this led to a broader inclusion of practices and a higher adoption rate than that reported by No-Till Farmer in some regions. We believe the misinterpretation of 1977 SCS definitions of residue management and minimum tillage by Heimlich has led to a definition which is too narrow to be useful. Minimum tillage, according to SCS, would have included some degree of residue management in all state interpretations in 1977. Consequently, many district conservationists would not have deemed it necessary to list residue management in addition to minimum tillage. In some regions, however, particularly where stubble mulching was important, residue management would have been listed in place of minimum tillage. Requiring both practices to be listed simultaneously in the comment model no doubt excludes legitimate minimum tillage activities. The Corn Belt adoption rates of 9%-12% in the comment model are considerably below the 25% adoption rate of minimum tillage and no-till systems reflected in data provided by Christensen and Norris for the Corn Belt in 1977. It is difficult to interpret the model results in the comment with such a narrowly defined dependent variable.

Background Whilst there have been studies on the risks and outcomes of MRSA colonization and infections in HIV-positive patients, local data is limited on the risk factors for MRSA colonization among these patients. We undertook this study in a tertiary HIV care centre to document the risk factors for colonization and to determine the prevalence of MRSA colonization among HIV-positive outpatients in Singapore. Methods This was a cross-sectional study in which factors associated with MRSA positivity among patients with HIV infection were evaluated. A set of standardized questionnaire and data collection forms were available to interview all recruited patients. Following the interview, trained nurses collected swabs from the anterior nares/axilla/groin (NAG), throat and peri-anal regions. Information on demographics, clinical history, laboratory results and hospitalization history were retrieved from medical records. Results MRSA was detected in swab cultures from at least 1 site in 15 patients (5.1%). Inclusion of throat and/or peri-anal swabs increased the sensitivity of NAG screening by 20%. Predictors for MRSA colonization among HIV-positive patients were age, history of pneumonia, lymphoma, presence of a percutaneous device within the past 12 months, history of household members hospitalized more than two times within the past 12 months, and a most recent CD4 count less than 200. Conclusions This study highlights that a proportion of MRSA carriers would have been undetected without multiple-site screening cultures. This study could shed insight into identifying patients at risk of MRSA colonization upon hospital visit and this may suggest that a risk factor-based approach for MRSA surveillance focusing on high risk populations could be considered.