Displaying all 9 publications

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  1. Poon SK, Chew WK
    Folia Parasitol., 1991;38(3):201-7.
    PMID: 1808029
    Faecal samples of 56 common house crows (Corvus splendens Vieillot) were collected from the Petaling Jaya and Kelang districts of Selangor, peninsular Malaysia, and examined for coccidia. Intestinal tracts of 8 of the above crows wee histologically examined under light microscopy to determine the site of coccidial infection and the endogenous stages present. Fifty three (94.6%) crows had coccidial oocysts morphologically conforming to only one species of Isospora in their faeces at the time they were examined. The sporulated oocysts were found to be Isospora corviae (Ray et al. 1952) which has been emended to I. corvi. These oocysts are redescribed in greater detail. Corvus splendens is a new host record for I. corvi. Coccidial infection was observed in all the intestinal tracts and generally confined to the anterior two thirds of the intestine. The parasites occurred within intestinal epithelial cells, located usually above the host cell nucleus. Developmental stages of both the asexual and sexual phases were found in the epithelium, and are deemed to be the endogenous stages of I. corvi on the basis of the oocysts recovered from the same crows used for histological study. These stages are described here for the first time. The prevalence of I. corvi, its relationship with the host C. splendens, and its probable transmission from C. macrorhynchus are discussed.
  2. Wong MS, Chew WL, Aw TC
    Pathology, 1999 Aug;31(3):225-9.
    PMID: 10503268
    Lipoprotein(a) [Lp(a)] is formed when apolipoprotein(a) is linked to low density lipoprotein (LDL)-cholesterol via a single disulfide bond. It is an independent risk factor for myocardial infarction and raised concentrations are associated with an increased risk of developing coronary artery disease. Singapore has a multi-racial population of 77% Chinese, 14% Malays and 7% Indians. Studies have shown that the Indians have significantly higher standardised mortality ratios (SMR) compared to the Chinese and the Malays. We measured serum Lp(a) concentrations in 803 healthy individuals recruited from the Multiphasic Health Screening Programme, using the Macra Lp(a) sandwich enzyme immunoassay kit (Strategics Diagnostics, Delaware, USA). Lp(a) concentrations were skewed in all three groups. Our population mean was 9.0 mg/dl, with 50th, 75th and 95th percentile values of 10.2, 19.8 and 43.1 mg/dl, respectively, which are lower than values reported from Caucasian populations (15.0, 29.0 and 60.0 mg/dl, respectively). Males had lower Lp(a) concentrations than females (P < 0.05). The Indian group had significantly higher concentrations (median 12.3 mg/dl) compared to their Chinese (median 9.6 mg/dl) and Malay (median 8.4 mg/dl) counterparts (P < 0.05). This could partly account for the higher SMR seen in the Indian population in Singapore. As serum Lp(a) concentrations are method- and population-dependent, we recommend that laboratories determine their own reference ranges by their method to avoid misclassification of the coronary heart disease (CHD) risk of patients.
  3. Lim AC, Chong VC, Chew WX, Muniandy SV, Wong CS, Ong ZC
    J Acoust Soc Am, 2015 Jul;138(1):404-12.
    PMID: 26233039 DOI: 10.1121/1.4923153
    Acoustic signals of the tiger-tail seahorse (Hippocampus comes) during feeding were studied using wavelet transform analysis. The seahorse "click" appears to be a compounded sound, comprising three acoustic components that likely come from two sound producing mechanisms. The click sound begins with a low-frequency precursor signal, followed by a sudden high-frequency spike that decays quickly, and a final, low-frequency sinusoidal component. The first two components can, respectively, be traced to the sliding movement and forceful knock between the supraorbital bone and coronet bone of the cranium, while the third one (purr) although appearing to be initiated here is produced elsewhere. The seahorse also produces a growling sound when under duress. Growling is accompanied by the highest recorded vibration at the cheek indicating another sound producing mechanism here. The purr has the same low frequency as the growl; both are likely produced by the same structural mechanism. However, growl and purr are triggered and produced under different conditions, suggesting that such "vocalization" may have significance in communication between seahorses.
  4. Chew WK, Kurahashi H, Nazni WA, Heo CC, Heah SK, Jeffery J, et al.
    Trop Biomed, 2012 Sep;29(3):489-92.
    PMID: 23018512
    Lispe orientalis Wiedemann, 1824 is recorded for the first time in peninsular Malaysia. Specimens were collected from a mushroom cultivation farm in Genting Highlands, Pahang (3°25'18"N 101°47'48"E). Previously, this species had been recorded from Azerbaijin, India, Russia, Tajikistan, Thailand, Turkey and South Korea. The male of Lispe orientalis can be determined by the following characteristics: body non-metallic, ashy gray, third antennal segment black, R5 cell not narrow apically, hind metatarsus normal, legs entirely black, femora with long bristle-like hairs on av and pv surfaces, hind tibia without av and pv seta and the palpi orangish in colour.
  5. How KN, Ho WC, Sundaran M, Wan Ahmal Kammal WSL, Lim PY, Chew W
    Clin Cosmet Investig Dermatol, 2023;16:3719-3729.
    PMID: 38152154 DOI: 10.2147/CCID.S422898
    PURPOSE: We aim to evaluate the effectiveness and tolerability of a sunscreen formulation containing licochalcone A (LicA) and L-carnitine (LC) as an adjuvant to adapalene in the management of acne and post-acne pigmentation (PAH).

    PATIENTS AND METHODS: A randomized, double-blind, active comparator-controlled trial of 51 patients aged 18 years or older with a clinical diagnosis of mild-to-moderate acne vulgaris was conducted at the Hospital Sultan Abdul Aziz Shah, Universiti Putra Malaysia. The efficacy and tolerability of once-daily adapalene 1.0% were assessed during the 2-week run-in period. Subsequently, patients were randomized to receive either an add-on investigational LicA-containing sunscreen or niacinamide-containing comparator sunscreen every 4 hourly during daytime for 4 weeks. Patients were followed up at Weeks 2 and 4 to assess for improvement in acne severity, PAH, calorimetric parameters and cutaneous tolerability.

    RESULTS: Two weeks of adapalene usage significantly improved acne severity; however, up to 52% of patients experienced dryness, burning and stinging. Adding LicA-containing or comparator sunscreens was associated with further improvement in acne severity, PAH and calorimetric parameters at the study endpoint. No significant differences in the cutaneous tolerability profiles were observed between treatment groups. Notably, significantly fewer patients receiving LicA-containing sunscreen developed scaliness at Week 4 compared with those in the comparator group. In addition, more patients receiving LicA-containing sunscreen reported less dryness, burning and stinging reactions than the comparator group. Importantly, more patients receiving LicA-containing sunscreen agreed that their treatment led to excellent improvement than the comparator group; of note, one patient reported that their condition worsened with the receipt of the comparator product.

    CONCLUSION: The concurrent use of LicA-containing sunscreen with adapalene may improve the cutaneous tolerance to adapalene among Malaysian patients.

  6. Nazni WA, Jeffery J, Lee HL, Lailatul AM, Chew WK, Heo CC, et al.
    Malays J Pathol, 2011 Jun;33(1):53-6.
    PMID: 21874753 MyJurnal
    A 73-year-old Chinese man was admitted to the Accident and Emergency Premorbid Ward of a local hospital in Malaysia. The patient complained of shortness of breath with cough and was in a semi-conscious state. He was later admitted to an intensive care unit (ICU) of the hospital. Six days after admission 5-6 maggots were recoverd from the nasal cavity. The maggots were identified as the third-instar larvae of Lucilia cuprina Wiedmann (Diptera: Calliphoridae) based on the morphological characteristics. This patient was classified as having nosocomial myiasis. The presence of the third instar larvae indicated that the infestation was not more than three to four days. An adult sarcophagid identified as Parasarcophaga ruficornis (Fabricius) caught in the ICU where the patient was warded provided further evidence of the potential for the nosocomial infestation.
  7. Yap CK, Wong KW, Al-Shami SA, Nulit R, Cheng WH, Aris AZ, et al.
    PMID: 33383875 DOI: 10.3390/ijerph18010195
    This study aimed to analyse ten trace metal concentrations in the edible part of the freshwater clam Corbicula javanica and to provide a critical assessment of the potential risks to human health through consumption of this clam as food based on well-established indices and food safety guidelines. The clams were captured from a pristine original site and transplanted to other sites with different environmental qualities. The trace metal levels in the edible total soft tissue (TST) of the clam were below those of the food safety guidelines referred to except for Pb, which exceeded the permissible limit set by the European Commission (2006) and the US Food and Drug Administration/ Center for Food Safety and Applied Nutrition); Interstate Shellfish Sanitation Conference. (USFDA/CFSAN; ISSC) (2007). The estimated daily intake (EDI) values of the clam were found to be lower than the oral reference dose and the calculated target hazard quotient (THQ) and total THQ were found to be less than 1. Therefore, in conclusion, the human health risk for consumption of TST of C. javanica at both average and high-level were insignificant regardless of the environment it was exposed to.
  8. Yap CK, Chew W, Al-Mutairi KA, Al-Shami SA, Nulit R, Ibrahim MH, et al.
    PMID: 33924835 DOI: 10.3390/ijerph18094682
    The invasive weed Asystasia gangetica was investigated for its potential as a biomonitor and as a phytoremediator of potentially toxic metals (PTMs) (Cd, Cu, Ni, Pb, and Zn) in Peninsular Malaysia owing to its ecological resistance towards unfavourable environments. The biomonitoring potential of PTMs was determined based on the correlation analysis of the metals in the different parts of the plant (leaves, stems, and roots) and its habitat topsoils. In the roots, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 2.18, 9.22 to 139, 0.63 to 5.47, 2.43 to 10.5, and 50.7 to 300, respectively. In the leaves, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.16, 7.94 to 20.2, 0.03 to 6.13, 2.10 to 21.8, and 18.8 to 160, respectively. In the stems, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.25, 5.57 to 11.8, 0.23 to 3.69, 0.01 to 7.79, and 26.4 to 246, respectively. On the other hand, the phytoremediation potential of the five metals was estimated based on the bioconcentration factor (BCF) and the translocation factor (TF) values. Correlation analysis revealed that the roots and stems could be used as biomonitors of Cu, the stems as biomonitors of Ni, the roots and leaves as biomonitors of Pb, and all three parts of the plant as biomonitors of Zn. According to the BCF values, in the topsoil, the "easily, freely, leachable, or exchangeable" geochemical fractions of the five metals could be more easily transferred to the roots, leaves, and stems when compared with total concentrations. Based on the TF values of Cd, Ni, and Pb, the metal transfer to the stems (or leaves) from the roots was efficient (>1.0) at most sampling sites. The results of BCF and TF showed that A. gangetica was a good phytoextractor for Cd and Ni, and a good phytostabilizer for Cu, Pb, and Zn. Therefore, A. gangetica is a good candidate as a biomonitor and a phytoremediator of Ni, Pb, and Zn for sustainable contaminant remediation subject to suitable field management strategies.
  9. Yap CK, Chew W, Al-Mutairi KA, Nulit R, Ibrahim MH, Wong KW, et al.
    Biology (Basel), 2021 Dec 21;11(1).
    PMID: 35053001 DOI: 10.3390/biology11010002
    Human activities due to different land uses are being studied widely in many countries. This study aimed to determine the ecological risks and human health risk assessments (HHRA) of Cd, Pb, Ni, Cu, and Zn in the topsoils of six land uses in Peninsular Malaysia. The ranges of the potentially toxic metals (PTMs) in the soils (mg/kg, dry weight) of this study were 0.24-12.43 for Cd (mean: 1.94), 4.66-2363 for Cu (mean: 228), 2576-116,344 for Fe (mean: 32,618), 2.38-75.67 for Ni (mean: 16.04), 7.22-969 for Pb (mean: 115) and 11.03-3820 for Zn (mean: 512). For the ecological risk assessments, the potential ecological risk index (PERI) for single metals indicated that the severity of pollution of the five metals decreased in the following sequence: Cd > Cu > Pb > Zn > Ni. It was found that industry, landfill, rubbish heap, and mining areas were categorized as "very high ecological risk". For HHRA, the land uses of industry, landfill and rubbish heap were found to have higher hazard quotient (HQ) values for the three pathways (with the order: ingestion > dermal contact > inhalation ingestion) of the five metals for children and adults, when compared to the mining, plantation, and residential areas. The values for both the non-carcinogenic (Cd, Cu, Ni, and Zn), and carcinogenic risks (CR) for inhalation (Cd and Ni) obtained for children and adults in this study showed no serious adverse health impacts on their health. However, of public concern, the hazard index (HI), for Pb of children at the landfill (L-3) and the rubbish heap (RH-3) sites exceeded 1.0, indicating non-carcinogenic risk (NCR) for children. Therefore, these PERI and HHRA results provided fundamental data for PTMs pollution mitigation and environmental management in areas of different land uses in Peninsular Malaysia.
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