Displaying all 14 publications

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  1. Chua TH
    Trop Biomed, 2012 Mar;29(1):121-8.
    PMID: 22543612 MyJurnal
    According to the report of the Intergovernmental Panel on Climate Change (IPCC), Malaysia will experience an increase of 3-5°C in the future. As the development of the malaria parasite, Plasmodium falciparum, is sensitive to temperature, we investigated, using computer models, the effect of increase of 3º and 5ºC on the possible changes in the epidemiology of malaria transmission of P. falciparum in Malaysia. Four environmentally different locations were selected: Kuala Lumpur (KL), Cameron Highlands (CH), Kota Kinabalu (KK) and Kinabalu Park (KP). The extrinsic incubation period (EIP) was estimated using hourly temperatures and the mean daily temperatures. The EIP values estimated using the mean daily temperature were lower than those computed from hourly temperatures in warmer areas (KL, KK), but higher in the cooler areas (CH, KP). The computer simulations also indicated that the EIP will be decreased if the temperature was raised by 3º or 5ºC, with the effect more pronounced for the greater temperature increase, and for the cooler places. The vector cohort that is still alive at a time to transmit malaria (s(EIP)) also increased when the temperature was raised, with the increase more pronounced in the cooler areas. This study indicates an increase in temperature will have more significant effect in shortening the EIP in a cooler place (eg CH, KP), resulting in a greater s(EIP), and consequently increasing the transmission intensity and malaria risk. A temperature increase arising from the global climate change will likely affect the epidemiology of malaria in Malaysia, especially in the cooler areas.
  2. Lee WC, Chua T
    Malays Orthop J, 2021 Mar;15(1):138-140.
    PMID: 33880163 DOI: 10.5704/MOJ.2103.023
    Atypical femoral fractures (AFF) have low union rates. The use of teriparatide has been advocated for the post-operative healing of AFF, but the evidence is limited to case reports and some series due to its low incidence. We present a case series of four female patients to support the use of teriparatide after the surgical fixation of their AFF. Three of the patients had a complete AFF and one had an incomplete fracture. Their mean age was 70 (52 - 87) years, mean body mass index 24.6 (18.3 - 29.3), mean bone mineral density T-score of -2.3 (-4.8/-1.0), with a prior history of anti-resorptive therapy with bisphosphonates and denosumab. Teriparatide was started at an average of 8 (2-18) days post-fixation, with 20mcg daily for six months. Immediate full weight-bearing was permitted in three patients, while one was non-weight bearing for two months. The mean time to union was 12 (10 - 14) weeks. No side effects were observed over a mean follow-up of 58 (50 - 72) weeks. The use of teriparatide facilitated the quick union of AFF after surgical fixation. It appeared to be safe and promoted fracture healing in AFF.
  3. Arbaoui AA, Chua TH
    Trop Biomed, 2014 Mar;31(1):134-42.
    PMID: 24862053 MyJurnal
    Since a safe and effective mass vaccination program against dengue fever is not presently available, a good way to prevent and control dengue outbreaks depends mainly on controlling the mosquito vectors. Aedes aegypti mosquito populations can be monitored and reduced by using ovitraps baited with organic infusions. A series of laboratory experiments were conducted which demonstrated that the bacteria in bamboo leaf infusion produce volatile attractants and contact chemical stimulants attractive to the female mosquitoes. The results showed that the female mosquitoes laid most of their eggs (59.9 ± 8.1 vs 2.9 ± 2.8 eggs, P<0.001) in bamboo leaf infusions when compared to distilled water. When the fresh infusion was filtered with a 0.45 μm filter membrane, the female mosquitoes laid significantly more eggs (64.1 ± 6.6 vs 4.9 ± 2.6 eggs, P<0.001) in unfiltered infusion. However when a 0.8 μm filter membrane was used, the female laid significantly more eggs (62.0 ± 4.3 vs 10.1 ± 7.8 eggs, P<0.001) in filtrate compared to a solution containing the residue. We also found that a mixture of bacteria isolated from bamboo leaf infusion serve as potent oviposition stimulants for gravid Aedes mosquitoes. Aedes aegypti laid significantly more eggs (63.3 ± 6.5 vs 3.1 ± 2.4 eggs, P<0.001) in bacteria suspension compared to sterile R2A medium. Our results suggest microbial activity has a role in the production of odorants that mediate the oviposition response of gravid mosquitoes.
  4. Yuan W, Chua T, Kwek E
    Malays Orthop J, 2022 Nov;16(3):55-60.
    PMID: 36589381 DOI: 10.5704/MOJ.2211.010
    INTRODUCTION: Elective implant removal following healed extremity fractures remains controversial. This study aimed to evaluate the reasons and outcomes of implant removal after uneventful healing of limb fractures.

    MATERIALS AND METHODS: This is a prospective single-centre observational cohort study. Patients who sustained upper or lower extremity fractures that were fixed and healed uneventfully were included in the study when they elected to remove the implants. Patients were followed for six months post-operatively. Outcomes were assessed with patient satisfaction, symptoms resolution, and complications.

    RESULTS: A total of 43 patients were recruited from October 2016 to March 2019. Thirty-six patients (37 implants) were symptomatic. Pain and prominence were the most common complaints, present in 59.5% and 33.3% of patients, respectively. Cold weather pain was also not uncommon (19.0%). Pain improved in 91.3% of the patients who complained of pain. The 94.6% symptomatic patients had at least partial resolution of pre-operative symptoms. All the patients who completed follow-up were satisfied with the procedure. In two patients, there were broken and retained screws intra-operatively. Post-operative complication rate was 23.8%, although no major complications occurred.

    CONCLUSIONS: Implant removal after uneventful healing of extremity fractures is a safe procedure that conferred a predictable relief of symptoms and satisfactory outcomes in most.

  5. Suleiman M, Muhammad J, Jelip J, William T, Chua TH
    PMID: 29644840
    The horseshoe crab (Carcinoscorpius rotundicauda) is consumed by those
    residing near the coastal areas of Kota Marudu District in Malaysia, as it is considered
    a delicacy. During June to August, 2011 thirty cases of tetrodotoxin poisoning
    were reported from Kota Marudu District following ingestion of horseshoe
    crabs caught in Kota Marudu Bay. The purpose of this study is to describe this
    case series in order to determine risk factors to prevent further outbreaks. There
    were six confirmed and 24 probable cases of tetrodotoxin poisoning identified in
    the study area during the study period as diagnosed by clinical presentation and
    laboratory findings. Symptoms included dizziness (80%), circumoral and lingual
    numbness (80%), hand and feet numbness (63.3%), nausea and vomiting (30%)
    and weakness and difficulty in breathing (26.6%). Three cases (10%) died while 27
    cases recovered. Forty-seven percent of the cases had onset of symptoms within
    30 minutes of ingestion and 14% 31-60 minutes after ingestion of horseshoe crab
    meat. Urine samples were collected from the cases, while horseshoe crabs, cockles
    and sea water from the epidemic area were also taken for analysis. Tetrodotoxin
    was detected in the urine of six cases; the highest concentrations recorded were
    among the three cases who died. High tetrodotoxin concentrations were found
    in the hepatic cecum and eggs of the tested horseshoe crabs. Dinoflagellates were
    not detected in the sea water or cockle samples. Intensive health education was
    initiated quickly to stop other members of the Marudu Bay community from
    consuming the horseshoe crabs. This is the first documented epidemic of tetrodotoxin
    poisoning in Sabah.
  6. Polgar G, Khang TF, Chua T, Marshall DJ
    J Therm Biol, 2015 Jan;47:99-108.
    PMID: 25526660 DOI: 10.1016/j.jtherbio.2014.11.009
    The relationship between acute thermal tolerance and habitat temperature in ectotherm animals informs about their thermal adaptation and is used to assess thermal safety margins and sensitivity to climate warming. We studied this relationship in an equatorial freshwater snail (Clea nigricans), belonging to a predominantly marine gastropod lineage (Neogastropoda, Buccinidae). We found that tolerance of heating and cooling exceeded average daily maximum and minimum temperatures, by roughly 20°C in each case. Because habitat temperature is generally assumed to be the main selective factor acting on the fundamental thermal niche, the discordance between thermal tolerance and environmental temperature implies trait conservation following 'in situ' environmental change, or following novel colonisation of a thermally less-variable habitat. Whereas heat tolerance could relate to an historical association with the thermally variable and extreme marine intertidal fringe zone, cold tolerance could associate with either an ancestral life at higher latitudes, or represent adaptation to cooler, higher-altitudinal, tropical lotic systems. The broad upper thermal safety margin (difference between heat tolerance and maximum environmental temperature) observed in this snail is grossly incompatible with the very narrow safety margins typically found in most terrestrial tropical ectotherms (insects and lizards), and hence with the emerging prediction that tropical ectotherms, are especially vulnerable to environmental warming. A more comprehensive understanding of climatic vulnerability of animal ectotherms thus requires greater consideration of taxonomic diversity, ecological transition and evolutionary history.
  7. Mak KH, Chia KS, Kark JD, Chua T, Tan C, Foong BH, et al.
    Eur Heart J, 2003 Jan;24(2):151-60.
    PMID: 12573272
    AIMS: We compare the myocardial infarction (MI) event and mortality rates among Chinese, Malay and Indian residents of Singapore.

    METHODS: Residents, aged 20 to 64 years, with an MI event were identified from hospital discharge listings, postmortem reports, and the Registry of Births and Deaths. All pathology laboratories flagged patients with elevated creatine phosphokinase (CPK) levels. Modified MONICA (multinational monitoring of trends and determinants in cardiovascular disease) criteria were used for determining MI events.

    RESULTS: From 1991 to 1999, 12 481 MI events were identified. Chinese patients were older and less likely to have typical symptoms or previous MI. Malays had the highest peak CPK level. Among all three ethnic groups, MI event and age-adjusted case-fatality rates declined. Compared with Chinese, MI event rates were >2-fold and >3-fold higher, and age-standardized coronary mortality rates were 2.4 and 3.0 higher times for Malays and Indians, respectively. Malays have the highest 3.1-year case-fatality, with an adjusted hazard ratio of 1.26 (95% confidence interval, 1.14 to 1.38) compared with Chinese.

    CONCLUSION: We found strong ethnic differences in MI event, case-fatality and coronary mortality rates among the three ethnic groups in Singapore. While Indians have the greatest MI event rates, Malays have the highest case-fatality.

  8. Tan AT, Emmanuel SC, Tan BY, Teo WS, Chua TS, Tan BH
    Ann Acad Med Singap, 2002 Jul;31(4):479-86.
    PMID: 12161884
    INTRODUCTION AND METHODS: Cardiovascular diseases have progressively increased in importance as a major contributor of morbidity and mortality in Asia. However, many countries in Asia do not have nationwide systematically-collected and standardised data on myocardial infarction (MI). To accurately document the extent of atherosclerotic coronary heart disease in Singapore, a nationwide myocardial infarct registry was established in the mid-1986. Possible myocardial infarct events were identified through daily national lists of cardiac enzymes, hospital discharge codes, mortuary records and the national death registry. Data obtained from clinical history, cardiac enzymes and 12-lead electrocardiogram Minnesota codes were entered into an algorithm based on the WHO MONICA study. Cases identified as "definite" MI were included in the decade's review for this study.

    RESULTS: From 1988 to 1997, 13,048 myocardial infarct events were diagnosed with 3367 deaths. There was a 39.1% decline in mortality, with an average decline of 6.5% per year [95% confidence intervals (CI), -3.9% to -9.1%]. However, the decline in incidence was only 20.8% with an average decline of 2.4% per year (95% CI, -6.6% to -1.2%). The highest incidence and mortality rates for both genders were seen in the Indians, followed by the Malays and the Chinese.

    CONCLUSION: Over 10 years, from 1988 to 1997, we documented a significant fall in mortality from MI in Singapore. There was a smaller decline in the incidence of infarction. Singapore implemented a National Healthy Lifestyle Programme in 1992 as a 10-year effort. The disparity in the incidence and mortality may suggest that a more dramatic and immediate impact has taken place in mortality through therapeutic programmes; primary preventive programmes would be more difficult to evaluate and have a more gradual impact. Only with continual accurate data collection through the whole country, over a much longer period, can the relative value of preventive and therapeutic programmes in coronary heart disease be assessed.

  9. Tham SN, Lim JJ, Tay SH, Chiew YF, Chua TN, Tan E, et al.
    Ann Acad Med Singap, 1988 Oct;17(4):482-5.
    PMID: 3265604
    410 cases of psoriasis [282 males (68%) and 127 females (31%)] were interviewed and examined to study the nail changes. The prevalence of nail changes was 78.0% (males = females). Common changes were pitting (67.5%) and onycholysis (67.2%). Dystrophy of varying degrees occurred in 35.0%, subungual hyperkeratosis in 24.7%, discoloration in 18.4%, loss of nails in 2.8% and pustulation in 1.3%. Pitting and onycholysis was the most common combination (45.6%). Nail changes were significantly more common in patients who have moderate to severe psoriasis as compared with patients with mild psoriasis; in patients who have psoriasis for greater than 5 years as compared with patients who have psoriasis for less than 5 years; and in patients older than age 50 as compared with those aged less than 50. A definite correlation was found between the prevalence of nail changes and the presence of scalp and periungual psoriasis, and the presence of joint involvement.
  10. Aung TS, Gintarong T, Balingi DB, Emran A, Thein TT, Chua TH
    Trop Biomed, 2020 Mar 01;37(1):58-65.
    PMID: 33612718
    An outbreak of dengue in Kudat, northern Sabah in 2016-2017 provided an opportunity to investigate the circulating serotypes of dengue viruses of cases at Hospital Kudat. Between September 2016 and December 2017, a total of 156 dengue positive sera (tested positive by either NS1 antigen, or IgM and IgG antibody rapid test) were collected from dengue patients who had acute fever and showed signs and symptoms suggestive of dengue. RNA was extracted from the sera using QIAamp RNA Blood Mini Kit, and molecular amplification was performed using one-step RT-PCR kit, followed by nested PCR using HotStart Taq master mix kit with the primers of the dengue C-prM gene. There were 81 (52%) male and 75 (48%) female cases. The age group with the highest number of cases was the 10-19 years old, while the youngest infected was 8 months old and the oldest was 83 years old. RT-PCR results showed 88 sera dengue positive, 48 infected with a single serotype while another 40 with multiple serotypes. All four DENV serotypes were co-circulating during the outbreak period and DENV-1 was predominant. Molecular analysis also indicated 69.2%, 50.0%, 51.9% and 48.9% respectively of the NS1, IgM, IgG and IgM and IgG positive sera were RT-PCR positive for dengue. High number of cases were seen in December 2016, February and May 2017. The dengue outbreak might be related to switching of predominant serotype from DENV 4 to DENV 1.
  11. Lee KE, Umapathi T, Tan CB, Tjia HT, Chua TS, Oh HM, et al.
    Ann Neurol, 1999 Sep;46(3):428-32.
    PMID: 10482278 DOI: 10.1002/1531-8249(199909)46:3<428::AID-ANA23>3.0.C
    A novel Hendra-like paramyxovirus named Nipah virus (NiV) was the cause of an outbreak among workers from one abattoir who had contact with pigs. Two patients had only respiratory symptoms, while 9 patients had encephalitis, 7 of whom are described in this report. Neurological involvement was diverse and multifocal, including aseptic meningitis, diffuse encephalitis, and focal brainstem involvement. Cerebellar signs were relatively common. Magnetic resonance imaging scans of the brain showed scattered lesions. IgM antibodies against Hendra virus (HeV) were present in the serum of all patients. Two patients recovered completely. Five had residual deficits 8 weeks later.
  12. Reid CM, Yan B, Wan Ahmad WA, Bang LH, Hian SK, Chua T, et al.
    Int J Cardiol, 2014 Mar 1;172(1):72-5.
    PMID: 24480180 DOI: 10.1016/j.ijcard.2013.12.030
    Clinicians and other stakeholders recognize the need for clinical registries to monitor data in order to improve the outcome and quality of care in the delivery of medical interventions. The establishment of a collaboration across the Asia Pacific Region to inform on variations in patient and procedural characteristics and associated clinical outcomes would enable regional benchmarking of quality.
  13. de Carvalho LP, Gao F, Chen Q, Hartman M, Sim LL, Koh TH, et al.
    Eur Heart J Acute Cardiovasc Care, 2014 Dec;3(4):354-62.
    PMID: 24598820 DOI: 10.1177/2048872614527007
    the purpose of this study was to investigate differences in long-term mortality following acute myocardial infarction (AMI) in patients from three major ethnicities of Asia.
  14. Gao F, Lam CS, Yeo KK, Machin D, de Carvalho LP, Sim LL, et al.
    J Am Heart Assoc, 2016 10 06;5(10).
    PMID: 27792637
    BACKGROUND: We examined the influence of sex, ethnicity, and time on competing cardiovascular and noncardiovascular causes of death following acute myocardial infarction in a multiethnic Asian cohort.

    METHODS AND RESULTS: For 12 years, we followed a prospective nationwide cohort of 15 151 patients (aged 22-101 years, median age 63 years; 72.3% male; 66.7% Chinese, 19.8% Malay, 13.5% Indian) who were hospitalized for acute myocardial infarction between 2000 and 2005. There were 6463 deaths (4534 cardiovascular, 1929 noncardiovascular). Compared with men, women had a higher risk of cardiovascular death (age-adjusted hazard ratio [HR] 1.3, 95% CI 1.2-1.4) but a similar risk of noncardiovascular death (HR 0.9, 95% CI 0.8-1.0). Sex differences in cardiovascular death varied by ethnicity, age, and time. Compared with Chinese women, Malay women had the greatest increased hazard of cardiovascular death (HR 1.4, 95% CI 1.2-1.6) and a marked imbalance in death due to heart failure or cardiomyopathy (HR 3.4 [95% CI 1.9-6.0] versus HR 1.5 [95% CI 0.6-3.6] for Indian women). Compared with same-age Malay men, Malay women aged 22 to 49 years had a 2.5-fold (95% CI 1.6-3.8) increased hazard of cardiovascular death. Sex disparities in cardiovascular death tapered over time, least among Chinese patients and most among Indian patients; the HR comparing cardiovascular death of Indian women and men decreased from 1.9 (95% CI 1.5-2.4) at 30 days to 0.9 (95% CI 0.5-1.6) at 10 years.

    CONCLUSION: Age, ethnicity, and time strongly influence the association between sex and specific cardiovascular causes of mortality, suggesting that health care policy to reduce sex disparities in acute myocardial infarction outcomes must consider the complex interplay of these 3 major modifying factors.

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