Publications by authors named "Heng S"

The fast thermolysis processes of ammonium perchlorate (AP) and its chemical reaction mechanism under certain simulated conditions of combustion were systematically studied by means of T-Jump/FTIR technique. AP was flash-pyrolyzed under different pressure nitrogen atmosphere, with the heating rate of 1000 K x s(-1) and the set temperatures of 874 and 1 274 K. Thereafter, the real time species and concentration of its gaseous products were obtained and identified by using rapid scanning Fourier transform infrared (FTIR) in-situ spectroscopy.

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Influenza-Like Illness (ILI) sentinel surveillance was initiated by the Communicable Disease Control Department (CDC), Ministry of Health, Cambodia and its partners to evaluate the epidemiology of influenza and identify the circulating strains. The surveillance started in late 2006 in four sentinel sites. The objectives of this study were 1) to document the incidence of LI and confirmed influenza cases reported in the national surveillance system from 2006 to 2008, just after the system and the definition were revised, 2) to identify the strains of influenza virus, 3) to compare the major demographic and clinical characteristics between ILI patients having positive and negative tests for influenza virus.

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Bone morphogenetic proteins (BMPs) require major posttranslational modifications to become biologically active. One such key modification is endoproteolytic cleavage of the initially synthesized nonactive precursor protein to release the mature ligand. Here we show in a physiological context of uterine stromal decidualization that BMP2 cleavage is mediated by proprotein convertase 5/6 (PC6).

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This study aimed to evaluate the cost and effectiveness of introducing a live, attenuated vaccine (SA 14-14-2) against Japanese encephalitis (JE) into the immunization program. The study demonstrated that SA 14-14-2 immunization is cost-effective in controlling JE in Cambodia compared to no vaccination. Averting one disability-adjusted life year, from a societal perspective, through the introduction of SA 14-14-2 through routine immunization, or a combination of routine immunization plus a campaign targeting children 1-5 or 1-10 years of age, costs US$22, US$34 and US$53, respectively.

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The present study determined the pharmacokinetic profile of vancomycin in premature Malaysian infants. A one-compartment infusion model with first-order elimination was fitted to serum vancomycin concentration data (n = 835 points) obtained retrospectively from the drug monitoring records of 116 premature newborn infants. Vancomycin concentrations were estimated by a fluorescence polarization immunoassay.

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Natural products often contain unusual scaffold structures that may be elaborated by combinatorial methods to develop new drug-like molecules. Visual inspection of more than 128 natural products with some type of anti-diabetic activity suggested that a subset might provide novel scaffolds for designing potent inhibitors against fructose 1,6-bisphosphatase (FBPase), an enzyme critical in the control of gluconeogenesis. Using in silico docking methodology, these were evaluated to determine those that exhibited affinity for the AMP binding site.

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Diffusion tensor imaging (DTI) is a neuroimaging technique with the potential to elucidate white matter abnormalities. Recently, it has been applied to help in better understanding of the pathophysiology of bipolar disorder (BD). This review sought to synthesise existing literature on DTI studies in BD, summarise current findings and highlight brain regions that have consistently been implicated in BD, as well as posit possible future directions for DTI research in BD.

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A cohort of Japanese encephalitis (JE) survivors in Cambodia and Viet Nam were assessed at least 4 months after hospital discharge in order to understand the extent of disability after JE. We used a simple assessment tool which focuses on the impact on daily life. In total, 64 disability assessments were conducted: 38 in Cambodia and 26 in Viet Nam.

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Background: There is little information about influenza disease among the Cambodian population. To better understand the dynamics of influenza in Cambodia, the Cambodian National Influenza Center (NIC) was established in August 2006. To continuously monitor influenza activity, a hospital based sentinel surveillance system for ILI (influenza like illness) with a weekly reporting and sampling scheme was established in five sites in 2006.

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The identification of a proper lead compound for fructose 1,6-bisphosphatase (FBPase) is a critical step in the process of developing novel therapeutics against type-2 diabetes. Herein, we have successfully generated a library of allosteric inhibitors against FBPase as potential anti-diabetic drugs, of which, the lead compound 1b was identified through utilizing a virtual high-throughput screening (vHTS) system, which we have developed. The thiazole-based core structure was synthesized via the condensation of alpha-bromo-ketones with thioureas and substituents on the two aryl rings were varied.

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Pulsed field gel electrophoresis (PFGE), the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility.

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Introduction: Pertussis is a worldwide, highly communicable, vaccine-preventable respiratory disease and is a frequent but often underestimated cause of prolonged cough illness in adults. Immunity from childhood pertussis immunization is thought to last only up to 10 years. The incidence of adult pertussis has been estimated to be 200 to 500 per 100,000 persons-years.

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A series of inhibitors of the aspartate transcarbamoylase, an enzyme involved in pyrimidine nucleotide biosynthesis, has been synthesized. These inhibitors are analogues of a highly potent inhibitor of this enzyme, N-phosphonacetyl-L-aspartate (PALA). Analogues have been synthesized with modifications at the alpha- and beta-carboxylates as well as at the aspartate moiety.

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Escherichia coli aspartate transcarbamoylase (ATCase) catalyzes the committed step in pyrimidine nucleotide biosynthesis, the reaction between carbamoyl phosphate (CP) and l-aspartate to form N-carbamoyl-l-aspartate and inorganic phosphate. The enzyme exhibits homotropic cooperativity and is allosterically regulated. Upon binding l-aspartate in the presence of a saturating concentration of CP, the enzyme is converted from the low-activity low-affinity T state to the high-activity high-affinity R state.

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This study reports trends in HIV-1 incidence in Cambodia among different target groups in the HIV-1 Sentinel Surveillance Program in 1999, 2000, and 2002, using the newly developed IgG capture BED-enzyme (HIV subtypes B, E and D) immunoassay (BED-CEIA). HIV-1-positive specimens (n=3599) from 4 sentinel groups in the HIV-1 Sentinel Surveillance Program from 1999 to 2002-brothel-based commercial sex workers (CSWs), indirect commercial sex workers (IDSWs), police, and women attending antenatal clinics (ANCs)-were tested using the BED-CEIA. Annualized incidence rates were calculated for each group and each geographic region.

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The study investigated whether clients of sex workers are a bridge for transmission of HIV to the general population of Cambodia. We interviewed and collected blood from 468 clients attending 30 randomly selected brothels in three provinces of Cambodia. The levels of HIV knowledge and condom use, and prevalence of HIV (9.

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This is the second survey of schoolchildren in Khon Kaen, Northeastern Thailand, using the Thai version of the ISAAC questionnaire to examine the trend in the prevalence of asthma, allergic rhinitis and eczema, and to compare the results with the ISAAC Phase I data. We analyzed 5,075 questionnaires comprising 2,119 six- to seven- and 2,956 thirteen- to fourteen-year-old children (48 and 42 percent male, respectively). The cumulative vs.

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This paper presents an overview of the Breast Cancer Risk Assessment (BCRA) Tool, assessing the credibility of the BCRA tool in estimating the risk of developing breast cancer for Asians and the carrying out of tests to identify the changes in the risks that follow with changes in one or more risk factors of the tool. It is essential to increase the awareness of women of their risk of developing breast cancer, as it is not surprising that some women may not even be conscious of the individual factors that might contribute to the increase of their risk of developing breast cancer. On the other hand, relatively accurate means of determining increases in relative risks of developing breast cancer due to changes in some of the risk factors are also important.

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We investigated the etiology of acute lower respiratory infection (ALRI) in children under 5 admitted to Srinagarind Hospital. The causative bacteria and viruses were determined by hemoculture and viral isolation from blood and nasopharyngeal aspirate samples. Antigens of respiratory syncytial virus (RSV) and Chlamydia trachomatis were detected using EIA.

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This survey of schoolchildren from Khon Kaen, Northeast Thailand used the standardized ISAAC questionnaires to estimate the prevalence of asthma and other allergic diseases and to compare the results with two previous studies. A total of 6,068 questionnaires were analyzed (2,658, 45.6% males from the 6 to 7 years old group and 3,410, 49.

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Background: The spread of human immunodeficiency virus (HIV) in Cambodia is mainly caused by sexual transmission and the high-risk group in this country are female commercial sex workers (CSW). There are two types of CSW, direct CSW (DCSW) and indirect CSW (IDCSW), who are different from each other in sexual activities. This study was conducted in order to describe the risk factors on HIV for each type of CSW, and to establish effective preventive strategies against the HIV epidemic among CSW.

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To describe epidemiological features on HIV prevalence among female commercial sex workers (CSWs), a cross-sectional study on sexual behaviour and serological prevalence was carried out in Cambodia. The CSWs were interviewed on their demographic characters and behaviour and their blood samples were taken for testing on sexually transmitted diseases, including HIV, Chlamydia trachomatis, syphilis, and hepatitis B. Associations between risk factors and HIV seropositivity were analysed.

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Contact mechanics of ultra high molecular weight polyethylene (UHMWPE) cups against metallic femoral heads for artificial hip joints is considered in this study. Both the experimental measurement of the contact area and the finite element prediction of the contact radius, maximum contact pressure and maximum Von Mises stress have been carried out for a wide range of contemporary artificial hip joints. Good agreement of the contact radius has been found between the experimental measurements and the finite element predictions based upon an elastic modulus of 1000 MPa and a Poisson's ratio of 0.

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The human immunodeficiency virus (HIV-1) uses the CD4 molecule, expressed by T helper cells and activated macrophages, as a receptor for entry into host cells. In tissues co-infected with herpes simplex type 1 (HSV-1), HIV-1 virions were observed to infect keratinocytes, which, because they lack the CD4 molecule, are normally incapable of being infected by HIV-1. Although a number of other viruses have been reported to enhance HIV-1 viral transcription in vitro, this is the first in-vivo report to our knowledge of reciprocal enhancement of viral replication associated with co-infection of keratinocytes and macrophages by HIV-1 and HSV-1 in patients with AIDS and non-genital herpes simplex lesions.

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The expression of Ulex europaeus agglutinin (UEA I) binding sites on cell-surface glycoproteins has been used as a marker for terminal differentiation. Increased number of UEA I binding sites of L-fucose specificity have been demonstrated in psoriatic epidermis. The results of lectin-binding studies in a series of biopsies taken sequentially (0 min, 5 min, 24 h, 7 days and 8 weeks) after tape-stripping of uninvolved skin in 12 psoriatic patients (three of whom were taking diltiazem, a calcium blocker at the time of the study) and six controls are presented.

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