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Search Results: 1 - 10 of 208843 matches for " Tun L. Thein "
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Implications of Discordance in World Health Organization 1997 and 2009 Dengue Classifications in Adult Dengue
Victor C. Gan, David C. Lye, Tun L. Thein, Frederico Dimatatac, Adriana S. Tan, Yee-Sin Leo
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060946
Abstract: Background Revised dengue guidelines were published by the World Health Organization (WHO) in 2009 addressing severe dengue cases not classified by dengue hemorrhagic fever (DHF) and shock syndrome (DSS). Methods and Principal Findings We conducted a retrospective cohort study to compare WHO 2009 and 1997 classifications using 1278 adult dengue cases confirmed by polymerase chain reaction assay from Singapore epidemics in 2004 and 2007 (predominantly serotype 1 and 2 respectively).DHF occurred in 14.3%, DSS 2.7% and severe dengue 16.0%. The two WHO dengue classifications were discordant in defining severe disease (p<0.001). Five DSS patients (15%) were classified as non-severe dengue without warning signs. Of severe dengue patients, 107 did not fulfil DHF criteria. Of these, 14.9% had self-resolving isolated elevated aminotransferases, 18.7% gastrointestinal bleeding without hemodynamic compromise and 56.1% plasma leakage with isolated tachycardia. We compared both guidelines against requirement for intensive care including the single death in this series: all six had severe dengue; only four had DHF as two lacked bleeding manifestations but had plasma leakage. Increasing length of hospitalization was noted among severe cases with both classifications but the trend was only statistically significant for WHO 2009. Length of hospitalization was significantly longer for severe plasma leakage compared with severe bleeding or organ impairment. Requirement for hospitalization increased using WHO 2009 from 17.0% to 51.3%. Conclusions While the WHO 2009 dengue classification is clinically useful, we propose retaining criteria for plasma leakage and hemodynamic compromise from WHO 1997, and refining definitions of severe bleeding and organ impairment to improve clinical relevance having found that differences in these accounted for the discordance between classifications. Findings from our retrospective study may be limited by the study site - a tertiary referral center in a hyperendemic country - and should be evaluated in a wider range of geographic settings.
Confirmed adult dengue deaths in Singapore: 5-year multi-center retrospective study
Yee-Sin Leo, Tun L Thein, Dale A Fisher, Jenny G Low, Helen M Oh, Rajmohan L Narayanan, Victor C Gan, Vernon J Lee, David C Lye
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-123
Abstract: We conducted a multi-center retrospective chart review of all confirmed adult dengue deaths in Singapore from 1 January 2004 to 31 December 2008.Of 28 adult dengue deaths, median age was 59 years. Male gender comprised 67.9% and co-morbidities existed in 75%. From illness onset, patients presented for admission at a median of 4 days and death occurred at a median of 12 days. Intensive care admission was required in 71.4%. Probable dengue was diagnosed in 32.1% by WHO 1997 criteria and 78.6% by WHO 2009. The earliest warning sign was persistent vomiting at a median of 1.5 days. Hematocrit change ≥20% concurrent with platelet count <20 × 10^9/L was associated with the shortest interval to death at a median of 3 days. Only 35.7% of death cases fulfilled DHF criteria by WHO 1997 versus severe dengue in 100.0% by WHO 2009 criteria. Deaths were due to shock and organ failure. Acute renal impairment occurred in 71.4%, impaired consciousness 57.1% and severe hepatitis 53.6%.In our adult fatal dengue cohort, WHO 2009 criteria had higher sensitivity in diagnosing probable dengue and severe dengue compared with WHO 1997. As warning signs, persistent vomiting occurred early and hematocrit change ≥20% concurrent with platelet count <20 × 10^9/L preceded death most closely.Dengue is the most important arthropod-borne viral disease in humans. The World Health Organization (WHO) has estimated that 1.8 billion people, or more than 70% of the global at-risk population, live in the WHO Southeast Asia and the Western Pacific regions which account for nearly 75% of current global disease burden from dengue [1]. Singapore, a developed island city-state in Southeast Asia has experienced resurgent dengue epidemics since the 1990s after previous decades of vector control effectively reduced the Aedes house index [2]. In addition, dengue infections in Singapore in recent years have shifted from primarily a childhood disease to that of adults [2]. With this resurgence, the classification of d
Risk Factors for Fatality among Confirmed Adult Dengue Inpatients in Singapore: A Matched Case-Control Study
Tun-Linn Thein, Yee-Sin Leo, Dale A. Fisher, Jenny G. Low, Helen M. L. Oh, Victor C. Gan, Joshua G. X. Wong, David C. Lye
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081060
Abstract: Objectives To identify demographic, clinical and laboratory risk factors for death due to dengue fever in adult patients in Singapore. Methods Multi-center retrospective study of hospitalized adult patients with confirmed dengue fever in Singapore between 1 January 2004 and 31 December 2008. Non-fatal controls were selected by matching age and year of infection with fatal cases. World Health Organization 1997, 2009 criteria were applied to define dengue hemorrhagic fever (DHF), warning signs and severe dengue. Statistical significance was assessed by conditional logistic regression modeling. Results Significantly more fatal cases than matched controls had pre-existing co-morbid conditions, and presented with abdominal pain/tenderness. Median pulse rates were significantly higher while myalgia was significantly less frequent in cases. . Fatal cases also had higher leucocyte counts, platelet counts, serum sodium, potassium, urea, creatine and bilirubin levels on admission compared to controls. There was no statistical significant difference between the prevalence of DHF and hematocrit level among cases and controls. Multivariate analysis showed myalgia and leucocyte count at presentation were independent predictors of fatality (adjusted odds ratios 0.09 and 2.94 respectively). None of the controls was admitted to intensive care unit (ICU) or given blood transfusion, while 71.4% and 28.6% of fatal cases received ICU admission and blood transfusion. Conclusions Absence of myalgia and leucocytosis on admission were independently associated with fatality in our matched case-control study. Fatalities were also commonly associated with co-morbidities and clinicians should be alarmed if dengue patients fulfilled severe dengue case definition on admission.
Predictive Tools for Severe Dengue Conforming to World Health Organization 2009 Criteria
Luis R. Carrasco,Yee Sin Leo ,Alex R. Cook,Vernon J. Lee,Tun L. Thein,Chi Jong Go,David C. Lye
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002972
Abstract: Background Dengue causes 50 million infections per year, posing a large disease and economic burden in tropical and subtropical regions. Only a proportion of dengue cases require hospitalization, and predictive tools to triage dengue patients at greater risk of complications may optimize usage of limited healthcare resources. For severe dengue (SD), proposed by the World Health Organization (WHO) 2009 dengue guidelines, predictive tools are lacking. Methods We undertook a retrospective study of adult dengue patients in Tan Tock Seng Hospital, Singapore, from 2006 to 2008. Demographic, clinical and laboratory variables at presentation from dengue polymerase chain reaction-positive and serology-positive patients were used to predict the development of SD after hospitalization using generalized linear models (GLMs). Principal findings Predictive tools compatible with well-resourced and resource-limited settings – not requiring laboratory measurements – performed acceptably with optimism-corrected specificities of 29% and 27% respectively for 90% sensitivity. Higher risk of severe dengue (SD) was associated with female gender, lower than normal hematocrit level, abdominal distension, vomiting and fever on admission. Lower risk of SD was associated with more years of age (in a cohort with an interquartile range of 27–47 years of age), leucopenia and fever duration on admission. Among the warning signs proposed by WHO 2009, we found support for abdominal pain or tenderness and vomiting as predictors of combined forms of SD. Conclusions The application of these predictive tools in the clinical setting may reduce unnecessary admissions by 19% allowing the allocation of scarce public health resources to patients according to the severity of outcomes.
Prevention and Treatment of Venous Thromboembolism with New Oral Anticoagulants: A Practical Update for Clinicians
Nay Min Tun,Thein Hlaing Oo
Thrombosis , 2013, DOI: 10.1155/2013/183616
Abstract:
Prevention and Treatment of Venous Thromboembolism with New Oral Anticoagulants: A Practical Update for Clinicians
Nay Min Tun,Thein Hlaing Oo
Thrombosis , 2013, DOI: 10.1155/2013/183616
Abstract: Traditional anticoagulants, such as warfarin and enoxaparin, have several limitations, including parenteral administration, need for laboratory monitoring, and ongoing dose adjustment, which may limit optimal patient care. Newer oral anticoagulants, such as direct thrombin inhibitors (e.g., dabigatran etexilate) and direct factor Xa inhibitors (e.g., rivaroxaban, apixaban, and edoxaban), have been developed to overcome these drawbacks, and thereby improve patient care. Several of these agents have been approved for use in the prevention and treatment of venous and/or systemic thromboembolism. The objective of this paper is to provide an overview of the available clinical trial data for these new oral anticoagulants in the prevention and treatment of venous thromboembolism and a practical update for clinicians. 1. Introduction Venous thromboembolism (VTE) comprises deep vein thrombosis (DVT) and pulmonary embolism (PE). Although the exact incidence of VTE is not known, it is estimated to affect 900,000 patients each year in the United States [1]. Approximately one-third of these cases are fatal pulmonary emboli, and the remaining two-thirds are nonfatal episodes of symptomatic DVT or PE [1]. VTE is the second most common cause of extended hospital stay and the third most common cause of in-hospital mortality [2]. Because it causes considerable morbidity and mortality, VTE places a substantial burden on healthcare resources [3, 4]. Without thromboprophylaxis, the incidence of hospital-acquired DVT based on objective diagnostic screening is 10–40% among medical or general surgical patients and 40–60% among patients who have undergone major orthopedic surgery such as total knee replacement (TKR), total hip replacement (THR), and hip fracture surgery [5]. Patients with cancer are at a greater risk of new or recurrent VTE than patients without cancer. VTE risk is 3- to 5-fold higher in cancer patients who are undergoing surgery and 6.5-fold higher in cancer patients receiving chemotherapy than in patients who do not have cancer [6, 7]. The efficacy of traditional anticoagulants in preventing VTE in patients undergoing major orthopedic surgery and in hospitalized acutely ill medical patients is well established [5, 8–11]. However, these agents have several limitations that may limit optimal patient care, such as their parenteral administration, need for laboratory monitoring, and ongoing dose adjustment (Table 1) [12–16]. Newer oral anticoagulants, such as direct thrombin inhibitors (e.g., dabigatran etexilate) and direct factor Xa inhibitors (e.g.,
Economic Impact of Dengue Illness and the Cost-Effectiveness of Future Vaccination Programs in Singapore
Luis R. Carrasco,Linda K. Lee,Vernon J. Lee,Eng Eong Ooi,Donald S. Shepard,Tun L. Thein,Victor Gan,Alex R. Cook ,David Lye,Lee Ching Ng,Yee Sin Leo
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001426
Abstract: 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.
250 MHz to 30 GHz, Unilateral Circuitmodel for Ingap/GaAs Hbt
Than Tun Thein;Choi Look Law;Kai Fu
PIER C , 2012, DOI: 10.2528/PIERC11101702
Abstract: A unilateral circuit model, which precisely predicts small signal response over a wide range of frequencies and bias points, is quantitatively analyzed and presented. The shortfall of current unilateral assumption and transformation technique is presented. A complete and explicit analysis is provided to develop a compact unilateral circuit model. The model is intended to predict input reflection, forward transmission and output reflection coefficients over wide range of frequencies. The technique is validated by transforming bilateral a small signal model of 3 x 3 μm x 40 μm, InGaP/GaAs HBT into its unilateral equivalent over the frequency range of 250 MHz to 30 GHz. The accuracy of the technique is corroborated at various bias conditions; collector current from 3 mA to 150 mA and collector-emitter voltage from 1 V to 5 V. Simulated results show very good agreement between small signal responses of transformed unilateral and bilateral circuit models.
Frequency Domain Dynamic Thermal Analysis in GaAs Hbt for Power Amplifier Applications
Than Tun Thein;Choi Look Law;Kai Fu
PIER , 2011, DOI: 10.2528/PIER11050301
Abstract: Dynamic temperature distributions in GaAs HBT are numerically analyzed in frequency domain as a function of power dissipation, frequency and space. Complete thermal characteristics, including frequency-dependent thermal impedance and phase lag behavior, are presented. The analysis is also extended for arbitrary periodic or aperiodic pulse heating operation to predict junction temperature of a Power Amplifier (PA) with non-constant envelope input signal. Dynamic junction temperatures of a single finger 2 μm x 20 μm GaAs HBT are predicted for square pulse envelope signal input with power levels varying with up to 10 dB above a nominal average level of 40 mW and with pulse widths ranging from 10 ns to 100 μs. With the input envelope signal amplitude of 10 dB above the average, the analytical results show that junction temperature rises from room temperature of 27C to 39C when heated by 10 ns pulse, increase to 36C by 100ns pulse, 105C by 1μs pulse and to 198C by 100 μs pulse. A novel setup is developed for nano-second pulsed measurements, and the analysis is validated through time domain on wafer pulsed measurements at three different power levels: 0 dB, 3 dB, and 6 dB above the average level. Results show that analytical results track well with measured junction temperature within the accuracy of ±5C over the entire measurement set.
Engineering Adaptive Digital Investigations using Forensics Requirements
Liliana Pasquale. Yijun Yu,Luca Cavallaro,Mazeiar Salehie,Thein Than Tun,Bashar Nuseibeh
Computer Science , 2014,
Abstract: A digital forensic investigation aims to collect and analyse the evidence necessary to demonstrate a potential hypothesis of a digital crime. Despite the availability of several digital forensics tools, investigators still approach each crime case from scratch, postulating potential hypotheses and analysing large volumes of data. This paper proposes to explicitly model forensic requirements in order to engineer software systems that are forensic-ready and guide the activities of a digital investigation. Forensic requirements relate some speculative hypotheses of a crime to the evidence that should be collected and analysed in a crime scene. In contrast to existing approaches, we propose to perform proactive activities to preserve important - potentially ephemeral - evidence, depending on the risk of a crime to take place. Once an investigation starts, the evidence collected proactively is analysed to assess if some of the speculative hypotheses of a crime hold and what further evidence is necessary to support them. For each hypothesis that is satisfied, a structured argument is generated to demonstrate how the evidence collected supports that hypothesis. Our evaluation results suggest that the approach provides correct investigative findings and reduces significantly the amount of evidence to be collected and the hypotheses to be analysed.
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