Displaying publications 21 - 40 of 98 in total

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  1. Toh BH, Sengupta S, Ang AH, White JC, Lau KS
    Ann Rheum Dis, 1973 Mar;32(2):151-6.
    PMID: 4120913 DOI: 10.1136/ard.32.2.151
    In West Malaysia RA appears to be less common than in temperate climates, but more common than in tropical Africa; furthermore, the incidence of gout and SLE is comparable. The clinical manifestations of RA are milder than those seen in more temperate climates. Subcutaneous rheumatoid nodules have not been observed. Positive serological tests for RF are significantly higher than in the general Malaysian population, but still lower than those reported for patients with RA in temperate climates. Of the three main ethnic groups, the highest incidence of positive results is found in the Chinese.
    Study site: Arthritis Clinic, University Hospital, Kuala Lumpur (University Malaya Medical Centre, UMMC, Kuala Lumpur, Malaysia)
  2. Ng YF, Ain N, Rafti NS, Lau KH
    Zootaxa, 2023 Jun 23;5306(5):586-594.
    PMID: 37518665 DOI: 10.11646/zootaxa.5306.5.6
    A new genus and three new species are described from the canopy of Dipterocarp forest in Pasoh Forest Research in Malaysia: Daunothrips gen. n., D. striatus sp. n., Scirtothrips convexum sp. n. and Scirtothrips longifacies sp. n. The morphological characters of these new members of the Scirtothrips genus-group are discussed and illustrated.
  3. Tan SG, Teng YS, Ganesan J, Lau KY, Lie-Injo LE
    Hum Genet, 1979 Jul 18;49(3):349-53.
    PMID: 289626
    Kadazans, the largest indigenous group in Sabah, northern Borneo, were surveyed for glyoxalase I, phosphoglucomutase I, red cell acid phosphatase, esterase D, adenosine deaminase, soluble glutamate pyruvate transaminase, soluble glutamate oxaloacetate transaminase, 6-phosphogluconate dehydrogenase, uridine monophosphate kinase, adenylate kinase, peptidase B and D, superoxide dismutase, C5, group specific component, haptoglobin and transferrin. Kadazans were found to be polymorphic for GLO I, PGM I, RCAP, esterase D, ADA, s-Gpt, 6PGD, UMPK, Gc, C5, haptoglobin and peptidase B. Rare variants were found for transferrin and peptidase D. No variant was found for s-Got, SOD and AK.
  4. Takaoka H, Sofian-Azirun M, Ya'cob Z, Chen CD, Lau KW, Pham HT
    Trop Biomed, 2014 Dec;31(4):742-8.
    PMID: 25776600 MyJurnal
    A total of 29 female black flies were captured by a hand net as they swarmed around humans in Tam Dao National Park, Vinh Phuc Province, Vietnam. They included one species of the subgenus Gomphostilbia (Simulium (Gomphostilbia) asakoae Takaoka & Davies) and five species of the subgenus Simulium, of which one species is described as Simulium (Simulium) vietnamense sp. nov. and the other four species (S. (S.) chungi Takaoka & Huang, S. (S.) grossifilum Takaoka & Davies, S. (S.) maenoi Takaoka & Choochote, and S. (S.) rufibasis Brunetti) are newly recorded from Vietnam.
  5. Lau KW, Chen CD, Lee HL, Izzul AA, Asri-Isa M, Zulfadli M, et al.
    Trop Biomed, 2013 Mar;30(1):36-45.
    PMID: 23665706 MyJurnal
    The aim of the present study was to determine the vertical distribution and abundance of Aedes mosquitoes in multiple storey buildings in Selangor and Kuala Lumpur, Malaysia. Ovitrap surveillance was conducted for 4 continuous weeks in multiple storey buildings in 4 residential areas located in Selangor [Kg. Baiduri (KB)] and Kuala Lumpur [Student Hostel of University of Malaya (UM), Kg. Kerinchi (KK) and Hang Tuah (HT)]. The results implied that Aedes mosquitoes could be found from ground floor to highest floor of multiple storey buildings and data from different elevation did not show significant difference. Ovitrap index for UM, KB, HT and KK ranged from 0 - 29.17%, 0 - 55.56%, 8.33 - 83.33% and 0 - 91.17% respectively. Aedes aegypti and Aedes albopictus were found breeding in HT, KK and KB; while only Ae. albopictus was obtained from UM. The results indicate that the invasion of Aedes mosquitoes in high-rise apartments could facilitate the transmission of dengue virus and new approaches to vector control in this type of residential area should be developed.
  6. Chen CD, Lee HL, Chan CK, Ang CL, Azahari AH, Lau KW, et al.
    Trop Biomed, 2009 Dec;26(3):360-5.
    PMID: 20237452
    The bioefficacy of nine commercial formulations of temephos against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae were evaluated in the laboratory. WHO larval bioassay with operational dosage of temephos at 1 mg/L was performed. The larval mortality was recorded every 5 minutes until complete mortality was achieved. All formulations of temephos exhibited various toxicity level against Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus. Generally, larvae of Cx. quinquefasciatus was susceptible to all formulations of temephos, followed by Ae. aegypti and Ae. albopictus.
  7. Takaoka H, Sofian-Azirun M, Chen CD, Lau KW, Halim MRA, Low VL, et al.
    Trop Biomed, 2018 Dec 01;35(4):951-974.
    PMID: 33601844
    Simulium (Gomphostilbia) dhangi sp. nov., S. (G.) sumbaense sp. nov. and S. (Nevermannia) wayani sp. nov. are described from the Lesser Sunda Archipelago, Indonesia. Simulium (G.) sumbaense sp. nov. is placed in the S. varicorne species-group and is characterized by the pupal gill with eight filaments arranged as (1+1+1+1+2)+2 from dorsal to ventral, while S. (G.) dhangi sp. nov., unplaced to group, is characterized by the pupal gill composed of two inflated trunks and four slender filaments all arising basally, and the short larval antenna as long as the stem of the labral fan. Simulium (N.) wayani sp. nov. belongs to the S. ruficorne species-group and is characterized by the female spermatheca with an unsclerotized neck, and pupal gill with four inflated filaments. The number of species of black flies from the archipelago increases from 19 to 22.
  8. Takaoka H, Sofian-Azirun M, Chen CD, Halim MRA, Lau KW, Low VL, et al.
    Trop Biomed, 2020 Sep 01;37(3):683-690.
    PMID: 33612782 DOI: 10.47665/tb.37.3.683
    Simulium (Simulium) contractum Takaoka from Sulawesi, Indonesia was known only as the pupa. Its female, male and mature larva are described for the first time. The tentative assignment of this species in the Simulium dumogaense species-group is confirmed by the adult characters including the female and male genitalia. The female and male of this species are similar to those of Simulium (Simulium) tumpaense Takaoka and Roberts but are distinguished by the yellowish femora.
  9. Elia-Amira NMR, Chen CD, Lau KW, Lee HL, Low VL, Norma-Rashid Y, et al.
    J Econ Entomol, 2018 09 26;111(5):2488-2492.
    PMID: 29982497 DOI: 10.1093/jee/toy184
    The present study aims to investigate the susceptibility status of Aedes albopictus (Skuse) collected from residential areas in Sabah, Malaysia towards eight WHO-recommended dosages of larvicides representing the classes of organophosphates and organochlorines. Field and reference strains of Ae. albopictus larvae were bioassayed in accordance to WHO standard methods using diagnostic dosages of bromophos, malathion, fenthion, fenitrothion, temephos, chlorpyrifos, dichlorodiphenyltrichloroethane (DDT), and dieldrin. The results revealed that Ae. albopictus was resistant (mortality < 90%) towards malathion, temephos, and DDT. In addition, most of the Ae. albopictus strains exhibited a wide range of susceptibilities against bromophos, with mortality ranged from 49.33 to 93.33%. On the contrary, only dieldrin was able to induce 100% mortality against all strains of Ae. albopictus. Tolerance to fenitrothion, fenthion, and chlorpyrifos, with mortality ranging from 81.33 to 97.33%, was also observed in this study.
  10. Chin AC, Chen CD, Low VL, Lee HL, Azidah AA, Lau KW, et al.
    J Econ Entomol, 2017 10 01;110(5):2247-2251.
    PMID: 29048583 DOI: 10.1093/jee/tox183
    This study was conducted using the glass chamber method to determine the susceptibility status of the dengue vector, Aedes aegypti (L.) from 11 states in Malaysia to commercial mosquito coils containing four different active ingredients, namely metofluthrin, d-allethrin, d-trans allethrin, and prallethrin. Aedes aegypti exhibited various knockdown rates, ranging from 14.44% to 100.00%, 0.00% to 61.67%, 0.00% to 90.00%, and 0.00% to 13.33% for metofluthrin, d-allethrin, d-trans allethrin, and prallethrin, respectively. Overall, mortality rates ranging from 0.00% to 78.33% were also observed among all populations. Additionally, significant associations were detected between the knockdown rates of metofluthrin and d-allethrin, and between metofluthrin and d-trans allethrin, suggesting the occurrence of cross-resistance within pyrethroid insecticides. Overall, this study revealed low insecticidal activity of mosquito coils against Ae. aegypti populations in Malaysia, and consequently may provide minimal personal protection against mosquito bites.
  11. Hamidah M, Mohd Hasmadi I, Chua LSL, Lau KH, Faridah-Hanum I, Yong WSY, et al.
    Heliyon, 2020 Jul;6(7):e04370.
    PMID: 32642589 DOI: 10.1016/j.heliyon.2020.e04370
    Malaysia is a megadiverse country and listed as one of the world's biodiversity hotspots. Land use changes and deforestation have led to the threat of, and extinction of plant species. In order to mitigate loss in population numbers, and to prevent species extinction events, Important Plant Areas (IPA) for Malaysia shall be identified. The identification of IPA is important to ensure that key natural areas are adequately protected and managed to preserve the species and its habitats. Currently, there are 1771 IPA identified globally and only seven tropical countries are actively involved excluding Malaysia. Inventory and biodiversity research are actively conducted in Malaysia, however, the initiative to identify IPA is still in its infancy. The first attempt for IPA identification was in the state of Terengganu by using herbarium database through scoring technique. In this paper, we discussed methods and criteria used in IPA identification globally. We also deliberated current IPA development in Terengganu and challenges such as collections biases and the need for a robust scoring technique to reduce judgement uncertainty. We suggested GIS based multi-criteria decision making, analytical hierarchy process and species distribution for Malaysian IPA. These strategies were considered to be effective tools in providing decision support for spatial planning aimed at plant conservation in Malaysia.
  12. Koh KC, Lau KM, Yusof SA, Mohamad AI, Shahabuddin FS, Ahmat NH, et al.
    Med J Malaysia, 2015 Dec;70(6):334-40.
    PMID: 26988205 MyJurnal
    INTRODUCTION: Misinterpretation of abbreviations by healthcare professionals has been reported to compromise patient safety. This study was done to determine the prevalence of abbreviations usage among medical doctors and nurses and their ability to interpret commonly used abbreviations in medical practice.

    METHODS: Seventy-seven medical doctors and eighty nurses answered a self-administered questionnaire designed to capture demographic data and information regarding abbreviation use in medical practice. Comparisons were made between doctors and nurses with regards to frequency and reasons for using abbreviations; from where abbreviations were learned; frequency of encountering abbreviations in medical practice; prevalence of medical errors due to misinterpretation of abbreviations; and their ability to correctly interpret commonly used abbreviations.

    RESULTS: The use of abbreviations was highly prevalent among doctors and nurses. Time saving, avoidance of writing sentences in full and convenience, were the main reasons for using abbreviations. Doctors learned abbreviations from fellow doctors while nurses learned from fellow nurses and doctors. More doctors than nurses reported encountering abbreviations. Both groups reported no difficulties in interpreting abbreviations although nurses reported often resorting to guesswork. Both groups felt abbreviations were necessary and an acceptable part of work. Doctors outperformed nurses in correctly interpreting commonly used standard and non-standard abbreviations.

    CONCLUSION: The use of standard and non-standard abbreviation in clinical practice by doctors and nurses was highly prevalent. Significant variability in interpretation of abbreviations exists between doctors and nurses.

  13. Lim KH, Jasvindar K, Cheong SM, Ho BK, Lim HL, Teh CH, et al.
    Tob Induc Dis, 2016;14:8.
    PMID: 27006650 DOI: 10.1186/s12971-016-0073-z
    BACKGROUND: The determination of smoking prevalence and its associated factors among the elderly could provide evidence-based findings to guide the planning and implementation of policy in order to will help in reducing the morbidity and mortality of smoking-related diseases, thus increase their quality of life. This paper describes the rate of smoking and identifies the factor(s) associated with smoking among the elderly in Malaysia.
    METHODS: A representative sample of 2674 respondents was obtained via a two-stage sampling method in proportion to population size. Face-to-face interviews were conducted using a set of standardized validated questionnaire. Data was weighted by taking into consideration the complex sampling design and non-response rate prior to data analysis. Univariable and multivariable logistic regression were used to determine the factor/s associated with smoking.
    RESULTS: The prevalence of non-smokers, ex-smokers and current smokers among Malaysians aged 60 years and above were 36.3 % (95 % CI = 32.7-39.8), 24.4 % (95 % CI = 21.2-27.5) and 11.9 % (95 % CI = 9.5-14.3), respectively. Current smokers were significantly more prevalent in men (28.1 %) than in women (2.9 %), but the prevalence declined with advancing age, higher educational attainment, and among respondents with known diabetes, hypertension and hypercholesterolemia. Multivariable analysis revealed that males (aOR, 18.6, 95 % CI 10.9-31.9) and other Bumiputras (aOR 2.58, 95 % CI 1.29-5.15) were more likely to smoke. in addition, elderly with lower educational attainment (aOR, 1.70, 95 % CI 1.24-7.41) and those without/unknown hypertension also reported higher likelihood to be current smokers (aOR 1.98, 95 % CI 1.35-2.83). However, there were no significant associations between respondents with no/unknown diabetes or hypercholesterolemia with smoking.
    CONCLUSIONS: In short, smoking is common among elderly men in Malaysia. Therefore, intervention programs should integrate the present findings to reduce the smoking rate and increase the smoking cessation rate among the elderly in Malaysia and subsequently to reduce the burden of smoking-related disease.
    Study name: National Health and Morbidity Survey (NHMS-2011)
  14. Nurin-Zulkifli IM, Chen CD, Wan-Norafikah O, Lee HL, Faezah K, Izzul AA, et al.
    PMID: 26867376
    Surveillance of mosquitoes and their distribution in association with rainfall, relative humidity, and temperature were conducted in selected suburban and forested areas, namely, Sungai Penchala (Kuala Lumpur) and Taman Alam (Selangor) for 12 months. Armigeres kesseli was the most abundant species in Sungai Penchala while Aedes butleri was the most dominant species in Taman Alam. A positive correlation between mosquito distribution and rainfall was observed in selected mosquito species in Sungai Penchala (Armigeres kesseli, r = 0.75; Armigeres subalbatus, r = 0.62; and Aedes albopictus, r = 0.65) and Taman Alam (Armigeres sp, r = 0.59; Ae. butleri, r = 0.85; and Ae. albopictus, r = 0.62). However, no significant cor- relation was found either between selected mosquito species in both study areas and relative humidity or temperature. Results obtained suggested that vector control programs to be conducted based on temporal distribution of vectors in order to achieve beneficial outcomes with effective costing.
  15. Elia-Amira NMR, Chen CD, Low VL, Lau KW, Haziqah-Rashid A, Amelia-Yap ZH, et al.
    J Med Entomol, 2019 10 28;56(6):1715-1725.
    PMID: 31290534 DOI: 10.1093/jme/tjz117
    Resistance status of Aedes albopictus (Diptera: Culicidae) collected from Sabah, East Malaysia, was evaluated against four major classes of adulticides, namely pyrethroid, carbamate, organochlorine, and organophosphate. Adult bioassays conforming to WHO standard protocols were conducted to assess knockdown and mortality rates of Ae. albopictus. Among tested pyrethroid adulticides, only cyfluthrin, lambda-cyaholthrin, and deltamethrin were able to inflict total knockdown. The other adulticide classes mostly failed to cause any knockdown; the highest knockdown rate was only 18.33% for propoxur. With regards to mortality rate, Ae. albopictus was unanimously susceptible toward all pyrethroids, dieldrin, and malathion, but exhibited resistance toward bendiocarb, propoxur, dichlorodiphenyltrichloroethane, and fenitrothion. Additionally, correlation analysis demonstrated cross-resistance between bendiocarb and propoxur, and malathion and propoxur. In conclusion, this study has disclosed that pyrethroids are still generally effective for Aedes control in Sabah, Malaysia. The susceptibility status of Ae. albopictus against pyrethroids in descending order was cyfluthrin > lambda-cyhalothrin > deltamethrin > etofenprox > permethrin.
  16. Azratul-Hizayu T, Chen CD, Lau KW, Azrizal-Wahid N, Tan TK, Lim YAL, et al.
    Trop Biomed, 2021 Sep 01;38(3):327-337.
    PMID: 34508340 DOI: 10.47665/tb.38.3.073
    This study aims to examine the efficacy of mosquito mat vaporizers on Aedes aegypti and their associated metabolic detoxication mechanisms. For this purpose, Aedes aegypti (Linnaeus) was collected from nine districts in Selangor, Malaysia and tested with mosquito vaporizing mat bioassays. The same populations were also subjected to biochemical assays to investigate activities of detoxifying enzymes, namely non-specific esterase (EST), glutathione-S-transferase (GST) and mixed function oxidase (MFO). The efficacy of Ae. aegypti on the active ingredients tested in decreasing order were d- allethrin > dimefluthrin > prallethrin with PBO > prallethrin. The results further indicated significant enhancement mean levels of EST, GST and MFO in pyrethroid-resistant populations. The mortality rate of Ae. aegypti in response to pyrethroid active ingredients was associated with MFO activity, suggesting it is an important detoxification enzyme for the populations tested. In view of the presence of resistance against household insecticide products, pyrethroid efficacy on Ae. aegypti populations needs to be monitored closely to ensure the implementation of an effective vector control program in Malaysia.
  17. Chen CD, Chin AC, Lau KW, Low VL, Lee HL, Lee PKY, et al.
    J Med Entomol, 2018 10 25;55(6):1651-1655.
    PMID: 30085203 DOI: 10.1093/jme/tjy130
    The bioefficacy of commercial mosquito coils containing four different active ingredients, namely metofluthrin, d-allethrin, d-trans allethrin, and prallethrin against Aedes albopictus (Skuse) (Diptera: Culicidae) from 10 states in Malaysia, was evaluated using the glass chamber method. In this study, Ae. albopictus exhibited various knockdown rates (50% knockdown time, KT50), ranging from 2.50 to 5.00 min, 2.50 to 7.00 min, 3.00 to 8.00 min, and 5.00 to 17.00 min for metofluthrin, d-trans allethrin, d-allethrin, and prallethrin, respectively. Overall, all strains of Ae. albopictus were most susceptible to metofluthrin, with mortality rates >80%. On the other hand, mortality rates ranging from 5.0 to 100% were observed from all populations exposed to d-trans allethrin, d-allethrin, and prallethrin. In addition, significant correlations between KT50 of metofluthrin and d-allethrin (r = 0.758, P = 0.011), metofluthrin and prallethrin (r = 0.676, P = 0.032), d-allethrin and d-trans allethrin (r = 0.832, P = 0.003), d-allethrin and prallethrin (r = 0.921, P = 0.000), and d-trans allethrin with prallethrin (r = 0.941, P = 0.000) were detected, suggesting some levels of cross-resistance within the pyrethroid insecticides. This study demonstrated that metofluthrin can induce high insecticidal activity in Ae. albopictus in Malaysia, followed by d-trans allethrin, d-allethrin, and prallethrin.
  18. Haziqah-Rashid A, Chen CD, Lau KW, Low VL, Sofian-Azirun M, Suana IW, et al.
    J Med Entomol, 2019 02 25;56(2):514-518.
    PMID: 30462258 DOI: 10.1093/jme/tjy208
    This study was conducted to monitor the susceptibility status of Aedes aegypti (Linnaeus) larvae in the Sunda Islands of Indonesia against various organophosphates and organochlorines. Larval bioassay was performed in accordance with the World Health Organization standard protocol. Field-collected and reference strains of Ae. aegypti larvae were tested against diagnostic doses of eight larvicides belonging to organophosphates and organochlorines, namely bromophos (0.050 mg/liter), chlopyrifos (0.002 mg/liter), fenitrothion (0.020 mg/liter), fenthion (0.025 mg/liter), malathion (0.125 mg/liter), temephos (0.012 mg/liter), DDT (0.012 mg/liter), and dieldrin (0.025 mg/liter). Mortality rates of larvae were recorded at 24-h posttreatment. This study showed that Ae. aegypti larvae from Padang, Samarinda, Manggarai Barat, and South Central Timor were susceptible to both fenitrothion and dieldrin (mortality rates ≥ 98%). About 6 out of 10 field strains of Ae. aegypti larvae were resistant (<80% mortality rates) against fenthion, whereas Ae. aegypti larvae from Kuningan, Samarinda, Sumba, and South Central Timor exhibited some degrees of resistance (mortality rates 80-98%). All field-collected Ae. aegypti larvae were resistant against diagnostic doses of chlorpyrifos, malathion, temephos, and DDT with mortality rates ranging from 0 to 74.67%. Continued insecticide susceptibility studies are essential to identify the efficacy of insecticides for an improved dengue vector control and to delay the development of insecticide resistance.
  19. Elia-Amira NMR, Chen CD, Low VL, Lau KW, Haziqah-Rashid A, Amelia-Yap ZH, et al.
    Trop Biomed, 2021 Jun 01;38(2):196-204.
    PMID: 34172711 DOI: 10.47665/tb.38.2.058
    Susceptibility status of Aedes albopictus (Skuse) sampled from residential areas in Interior, Sandakan and Tawau divisions of Sabah, Malaysia, was evaluated based on the WHOrecommended doses of organochlorine and organophosphate larvicides. To determine susceptibility status, larval bioassays were carried out and post 24-hour mortalities based on WHO resistance classifications were adopted. The results demonstrated that Ae. albopictus larvae were resistant toward 5 out of the 8 larvicides tested. Larvae from all populations were resistant against bromophos, fenitrothion, malathion, temephos and dichlorodiphenyltrichloroethane (DDT), with mortalities ranging from 0.00 to 89.33%. Dieldrin, on the other hand, could induce 100.00% mortalities in all populations, followed by fenthion and chlorpyrifos, with mortalities ranging from 97.33 to 100.00% and 81.33 to 100.00% respectively. Despite most populations exhibiting similitude in their resistance status, larvae from Sandakan exhibited the highest resistance level whereas the lowest level was observed in Keningau. In view of the inadequacy of some larvicides in controlling Ae. albopictus in this study, integrated management such as insecticide rotation or combination of interventions is warranted.
  20. Elia-Amira NMR, Chen CD, Low VL, Lau KW, Haziqah-Rashid A, Amelia-Yap ZH, et al.
    J Med Entomol, 2022 01 12;59(1):301-307.
    PMID: 34459477 DOI: 10.1093/jme/tjab146
    The efficacy of three groups of insect growth regulators, namely juvenile hormone mimics (methoprene and pyriproxyfen), chitin synthesis inhibitors (diflubenzuron and novaluron), and molting disruptor (cyromazine) was evaluated for the first time, against Aedes albopictus Skuse (Diptera: Culicidae) larvae from 14 districts in Sabah, Malaysia. The results showed that all field populations of Ae. albopictus were susceptible towards methoprene, pyriproxyfen, diflubenzuron, novaluron, and cyromazine, with resistance ratio values ranging from 0.50-0.90, 0.60-1.00, 0.67-1.17, 0.71-1.29, and 0.74-1.07, respectively. Overall, the efficacy assessment of insect growth regulators in this study showed promising outcomes and they could be further explored as an alternative to conventional insecticides.
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