Displaying publications 1 - 20 of 134 in total

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  1. White WT, Harris M
    Zootaxa, 2013;3752:172-84.
    PMID: 25229113
    Paragaleus tengi was previously considered to be the only member of this genus occurring in the Western Pacific, with Paragaleus randalli occurring in the Indian Ocean and allopatric in distribution. Recent molecular and morphological studies showed that P. randalli also occurs in the Western Pacific with records from Thailand, Malaysia and Indonesia previously mostly incorrectly attributed to P. tengi. This paper provides a redescription of P. tengi and confirms the presence of P. randalli from off Taiwan in the western North Pacific. These two species are morphologically very similar in appearance but differ in meristics, dentition, some coloration attributes and minor morphological characters. The conservation status of these two species needs to be reassessed based on this new information.
  2. Yokoyama S, Starmer WT
    Mol Biol Evol, 2017 03 01;34(3):525-534.
    PMID: 28087772 DOI: 10.1093/molbev/msw270
    Originating in Africa, the Zika virus (ZIKV) has spread to Asia, Pacific Islands and now to the Americas and beyond. Since the first isolation in 1947, ZIKV strains have been sampled at various times in the last 69 years, but this history has not been reflected in studying the patterns of mutation accumulation in their genomes. Implementing the viral history, we show that the ZIKV ancestor appeared sometime in 1930-1945 and, at that point, its mutation rate was probably less than 0.2 × 10-3/nucleotide site/year and subsequently increased significantly in most of its descendants. Sustaining a high mutation rate of 4 × 10-3/site/year throughout its evolution, the Ancestral Asian strain, which was sampled from a mosquito in Malaysia, accumulated 13 mutations in the 3'-untranslated region of RNA stem-loops prior to 1963, seven of which generate more stable stem-loop structures and are likely to inhibit cellular antiviral activities, including immune and RNA interference (RNAi) pathways. The seven mutations have been maintained in all Asian and American strains and may be responsible for serious medical problems we are facing today and offer testable hypotheses to examine their roles in molecular interactions during brain development.
  3. William T, Menon J
    Med J Malaysia, 2014 Aug;69 Suppl A:82-7.
    PMID: 25417955 MyJurnal
    One hundred and thirteen articles related to Malaria were found in a search through a database dedicated to indexing all original data relevant to medicine published in Malaysia between the years 2000-2013. Thirty eight articles were selected and reviewed on the basis of clinical relevance and future research implications. The epidemiology of malaria has undergone a significant change over the last decade with P. knowlesi, formerly a relatively unknown simian parasite rapidly becoming the most predominant malaria species to infect humans in Malaysia. The epidemiology, clinical features, diagnostic methods and treatment for P. knowlesi infection are described in these studies. In Malaysia, imported malaria from foreigners also poses a challenge. In view of these changes, new strategies on malaria control need to be devised and implemented, and treatment regimens need to be redefined to help Malaysia achieve the goal of malaria elimination by the year 2020.
  4. White WT, Moore AB
    Zootaxa, 2013;3752:199-213.
    PMID: 25229115
    The eagle ray Aetobatus flagellum (Bloch & Schneider, 1801) is redescribed based on new material from the Persian Gulf (Kuwait), Indonesia and Malaysia. A related but distinct species of Aetobatus from the western North Pacific, previously referred to as A. flagellum, is reported. Aetobatus flagellum is a medium-sized eagle ray which attains about 900 mm DW; males mature at approximately 500 mm DW. Aetobatus flagellum appears to be uncommon and restricted to estuary-influenced waters of the Indo-West Pacific. It is caught as gillnet bycatch where its habit of schooling, combined with probable small litter size, may make it particularly vulnerable to impacts from fisheries.
  5. Nakaya K, White WT, Ho HC
    Sci Rep, 2020 07 23;10(1):12280.
    PMID: 32703969 DOI: 10.1038/s41598-020-68923-1
    Two modes of oviparity are known in cartilaginous fishes, (1) single oviparity where one egg case is retained in an oviduct for a short period and then deposited, quickly followed by another egg case, and (2) multiple oviparity where multiple egg cases are retained in an oviduct for a substantial period and deposited later when the embryo has developed to a large size in each case. Sarawak swellshark Cephaloscyllium sarawakensis of the family Scyliorhinidae from the South China Sea performs a new mode of oviparity, which is named "sustained single oviparity", characterized by a lengthy retention of a single egg case in an oviduct until the embryo attains a sizable length. The resulting fecundity of the Sarawak swellshark within a season is quite low, but this disadvantage is balanced by smaller body, larger neonates and quicker maturation. The Sarawak swellshark is further uniquely characterized by having glassy transparent egg cases, and this is correlated with a vivid polka-dot pattern of the embryos. Five modes of lecithotrophic (yolk-dependent) reproduction, i.e. short single oviparity, sustained single oviparity, multiple oviparity, yolk-sac viviparity of single pregnancy and yolk-sac viviparity of multiple pregnancy were discussed from an evolutionary point of view.
  6. Philip N, William T, William DV
    Malays J Pathol, 2015 Apr;37(1):1-9.
    PMID: 25890607 MyJurnal
    Tuberculosis (TB) which is caused by Mycobacterium tuberculosis infects primarily the lungs but it also affects other parts of the body. Tuberculous meningitis (TBM) is the most severe form of TB and has the highest mortality and morbidity rate compared to other forms of TB. It is common in young children and HIV-infected patients, but is also seen in adults. Despite anti-tuberculosis treatment, TBM is still a major cause of death and neurological sequelae as treatment given to the patients is often delayed. Early diagnosis is challenging due to the non-specific symptoms of TBM and the low number of tubercle bacilli in cerebrospinal fluid (CSF). Until now, there is no established diagnostic method that can rapidly detect M. tuberculosis in TBM patients with high sensitivity and specificity. The emergence of drug resistant M. tuberculosis strains further complicates the diagnosis and treatment regimen of TBM. This review summarizes challenges of the currently used diagnostic methods and the potential future use of molecular diagnostic methods for TBM.
  7. Harrison WT, Plater MJ, Yin LJ
    Acta Crystallogr E Crystallogr Commun, 2016 Mar 1;72(Pt 3):407-11.
    PMID: 27006818 DOI: 10.1107/S2056989016002942
    The title compounds, C14H12O, (I), and C15H11BrO2, (II), were prepared and characterized as part of our studies of potential new photo-acid generators. In (I), which crystallizes in the ortho-rhom-bic space group Pca21, compared to P21/n for the previously known monoclinic polymorph [Cornella & Martin (2013 ▸). Org. Lett. 15, 6298-6301], the dihedral angle between the aromatic rings is 4.35 (6)° and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), mol-ecules are linked by O-H⋯π inter-actions involving both the major and minor -OH disorder components, generating [001] chains as part of the herringbone packing motif. The asymmetric unit of (II) contains two mol-ecules with similar conformations (weighted r.m.s. overlay fit = 0.183 Å). In the crystal of (II), both mol-ecules form carboxyl-ate inversion dimers linked by pairs of O-H⋯O hydrogen bonds, generating R 2 (2)(8) loops in each case. The dimers are linked by pairs of C-H⋯O hydrogen bonds to form [010] chains.
  8. Lau TY, Sylvi M, William T
    Malar J, 2013;12:445.
    PMID: 24321120 DOI: 10.1186/1475-2875-12-445
    The sulphadoxine/pyrimethamine (SDX/PYR) combination had been chosen to treat uncomplicated falciparum malaria in Malaysia for more than 30 years. Non-silent mutations in dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes are responsible for the resistance to pyrimethamine and sulphadoxine, respectively. This study reports the mutational analysis of pfdhfr and pfdhps in single Plasmodium falciparum infection isolates from the interior division of Sabah, Malaysian Borneo.
  9. 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.
  10. Mohd Iskandar BJ, William T, Daisy Vanitha J
    Med J Malaysia, 2018 04;73(2):106-109.
    PMID: 29703874 MyJurnal
    BACKGROUND: Leptospirosis is a zoonotic disease with symptoms ranging from a mild, febrile illness to a severe form with multiorgan failure. Severe leptospirosis may require medical interventions in the form of dialysis and/or mechanical ventilation and often leads to mortality. An exaggerated host immune response-in particular, a "cytokine storm"-that causes endothelial and organ damage is associated with the disease severity and mortality.

    METHODS: Microscopic agglutination test (MAT)-positive and MAT-negative human serum samples (n=30) from patients with leptospirosis were obtained from the Public Health Laboratory, Kota Kinabalu, Sabah, Malaysia and control serum samples (n=10) were obtained from healthy student volunteers. We estimated the levels of IL-1β, IL-6, IL-8, IL-10, and TNF-α in serum samples by a Luminex assay.

    RESULTS: The levels of IL-6, IL-8, and IL1-β were significantly higher in 13% of the patients with leptospirosis compared to the healthy controls, while the levels of IL-10 and TNF-α were not elevated in either group.

    CONCLUSION: Our data suggest that elevated levels of IL-6, IL- 8, and IL1-β may be associated with leptospirosis disease severity, which requires patient follow-up for confirmation.

  11. Daneshvar C, William T, Davis TME
    Parasitology, 2018 01;145(1):18-31.
    PMID: 28122651 DOI: 10.1017/S0031182016002638
    Plasmodium knowlesi is a simian malaria of primarily the macaque species of South East Asia. While it was known that human infections could be induced during the years of malariotherapy, naturally occurring P. knowlesi human infections were thought to be rare. However, in 2004, knowlesi infections became recognized as an important infection amongst human populations in Sarawak, Malaysian Borneo. Since then, it has become recognized as a disease affecting people living and visiting endemic areas across South East Asia. Over the last 12 years, clinical studies have improved our understanding of this potentially fatal disease. In this review article the current literature is reviewed to give a comprehensive description of the disease and treatment.
  12. Lim YK, Keng FS, Phang SM, Sturges WT, Malin G, Abd Rahman N
    PeerJ, 2019;7:e6758.
    PMID: 31041152 DOI: 10.7717/peerj.6758
    Marine algae have been reported as important sources of biogenic volatile halocarbons that are emitted into the atmosphere. These compounds are linked to destruction of the ozone layer, thus contributing to climate change. There may be mutual interactions between the halocarbon emission and the environment. In this study, the effect of irradiance on the emission of halocarbons from selected microalgae was investigated. Using controlled laboratory experiments, three tropical marine microalgae cultures, Synechococcus sp. UMACC 371 (cyanophyte), Parachlorella sp. UMACC 245 (chlorophyte) and Amphora sp. UMACC 370 (diatom) were exposed to irradiance of 0, 40 and 120 µmol photons m-2s-1. Stress in the microalgal cultures was indicated by the photosynthetic performance (Fv/Fm, maximum quantum yield). An increase in halocarbon emissions was observed at 120 µmol photons m-2s-1, together with a decrease in Fv/Fm. This was most evident in the release of CH3I by Amphora sp. Synechococcus sp. was observed to be the most affected by irradiance as shown by the increase in emissions of most halocarbons except for CHBr3 and CHBr2Cl. High positive correlation between Fv/Fm and halocarbon emission rates was observed in Synechococcus sp. for CH2Br2. No clear trends in correlation could be observed for the other halocarbons in the other two microalgal species. This suggests that other mechanisms like mitochondria respiration may contribute to halocarbon production, in addition to photosynthetic performance.
  13. Wong KS, Lim WTH, Ooi CW, Yeo LY, Tan MK
    Lab Chip, 2020 05 19;20(10):1856-1868.
    PMID: 32342089 DOI: 10.1039/d0lc00001a
    The presence of reactive species in plasma-activated water is known to induce oxidative stresses in bacterial species, which can result in their inactivation. By integrating a microfludic chipscale nebulizer driven by surface acoustic waves (SAWs) with a low-temperature atmospheric plasma source, we demonstrate an efficient technique for in situ production and application of plasma-activated aerosols for surface disinfection. Unlike bulk conventional systems wherein the water is separately batch-treated within a container, we show in this work the first demonstration of continuous plasma-treatment of water as it is transported through a paper strip from a reservoir onto the chipscale SAW device. The significantly larger surface area to volume ratio of the water within the paper strip leads to a significant reduction in the duration of the plasma-treatment, while maintaining the concentration of the reactive species. The subsequent nebulization of the plasma-activated water by the SAW then allows the generation of plasma-activated aerosols, which can be directly sprayed onto the contaminated surface, therefore eliminating the storage of the plasma-activated water and hence circumventing the typical limitation in conventional systems wherein the concentration of the reactive species diminishes over time during storage, resulting in a reduction in the efficacy of bacterial inactivation. In particular, we show up to 96% reduction in Escherichia coli colonies through direct spraying with the plasma-activated aerosols. This novel, low-cost, portable and energy-efficient hybrid system necessitates only minimal maintenance as it only requires the supply of tap water and battery power for operation, and is thus suitable for decontamination in home environments.
  14. Lim WTH, Ooi EH, Foo JJ, Ng KH, Wong JHD, Leong SS
    Ultrasound Med Biol, 2021 08;47(8):2033-2047.
    PMID: 33958257 DOI: 10.1016/j.ultrasmedbio.2021.03.030
    Early detection of chronic kidney disease is important to prevent progression of irreversible kidney damage, reducing the need for renal transplantation. Shear wave elastography is ideal as a quantitative imaging modality to detect chronic kidney disease because of its non-invasive nature, low cost and portability, making it highly accessible. However, the complexity of the kidney architecture and its tissue properties give rise to various confounding factors that affect the reliability of shear wave elastography in detecting chronic kidney disease, thus limiting its application to clinical trials. The objective of this review is to highlight the confounding factors presented by the complex properties of the kidney, in addition to outlining potential mitigation strategies, along with the prospect of increasing the versatility and reliability of shear wave elastography in detecting chronic kidney disease.
  15. Lim WTH, Ooi EH, Foo JJ, Ng KH, Wong JHD, Leong SS
    Ultrasonics, 2023 Aug;133:107046.
    PMID: 37247461 DOI: 10.1016/j.ultras.2023.107046
    The application of ultrasound shear wave elastography for detecting chronic kidney disease, namely renal fibrosis, has been widely studied. A good correlation between tissue Young's modulus and the degree of renal impairment has been established. However, the current limitation of this imaging modality pertains to the linear elastic assumption used in quantifying the stiffness of renal tissue in commercial shear wave elastography systems. As such, when underlying medical conditions such as acquired cystic kidney disease, which may potentially influence the viscous component of renal tissue, is present concurrently with renal fibrosis, the accuracy of the imaging modality in detecting chronic kidney disease may be affected. The findings in this study demonstrate that quantifying the stiffness of linear viscoelastic tissue using an approach similar to those implemented in commercial shear wave elastography systems led to percentage errors as high as 87%. The findings presented indicate that use of shear viscosity to detect changes in renal impairment led to a reduction in percentage error to values as low as 0.3%. For cases in which renal tissue was affected by multiple medical conditions, shear viscosity was found to be a good indicator in gauging the reliability of the Young's modulus (quantified through a shear wave dispersion analysis) in detecting chronic kidney disease. The findings show that percentage error in stiffness quantification can be reduced to as low as 0.6%. The present study demonstrates the potential use of renal shear viscosity as a biomarker to improve the detection of chronic kidney disease.
  16. Fornace KM, Drakeley CJ, William T, Espino F, Cox J
    Trends Parasitol, 2014 Nov;30(11):514-9.
    PMID: 25443854 DOI: 10.1016/j.pt.2014.09.001
    The potential applications of unmanned aerial vehicles (UAVs), or drones, have generated intense interest across many fields. UAVs offer the potential to collect detailed spatial information in real time at relatively low cost and are being used increasingly in conservation and ecological research. Within infectious disease epidemiology and public health research, UAVs can provide spatially and temporally accurate data critical to understanding the linkages between disease transmission and environmental factors. Using UAVs avoids many of the limitations associated with satellite data (e.g., long repeat times, cloud contamination, low spatial resolution). However, the practicalities of using UAVs for field research limit their use to specific applications and settings. UAVs fill a niche but do not replace existing remote-sensing methods.
  17. Muhammad Redzwan SR, Ralph AP, Sivaraman Kannan KK, William T
    Med J Malaysia, 2015 Jun;70(3):200-4.
    PMID: 26248785 MyJurnal
    Clinical experience with extensively Drug Resistant tuberculosis (XDR-TB) has not been reported in Malaysia before. We describe the clinical characteristics, risk factors, progress and therapeutic regimen for a healthcare worker with XDR-TB, who had failed therapy for multidrug resistant TB (MDR TB) in our institution. This case illustrates the risk of TB among healthcare workers in high TB-burden settings, the importance of obtaining upfront culture and susceptibility results in all new TB cases, the problem of acquired drug resistance developing during MDR-TB treatment, the challenges associated with XDR-TB treatment regimens, the value of surgical resection in refractory cases, and the major quality of life impact this disease can have on young, economically productive individuals.
  18. Philip N, Rodrigues KF, William T, John DV
    Genom Data, 2016 Sep;9:137-9.
    PMID: 27556011 DOI: 10.1016/j.gdata.2016.08.007
    Mycobacterium tuberculosis (M. tuberculosis) is the causative agent of tuberculosis (TB) that causes millions of death every year. We have sequenced the genome of M. tuberculosis isolated from cerebrospinal fluid (CSF) of a patient diagnosed with tuberculous meningitis (TBM). The isolated strain was referred as M. tuberculosis SB24. Genomic DNA of the M. tuberculosis SB24 was extracted and subjected to whole genome sequencing using PacBio platform. The draft genome size of M. tuberculosis SB24 was determined to be 4,452,489 bp with a G + C content of 65.6%. The whole genome shotgun project has been deposited in NCBI SRA under the accession number SRP076503.
  19. Yaakob Y, Rodrigues KF, Opook F, William T, John DV
    Malays J Med Sci, 2017 Oct;24(5):44-51.
    PMID: 29386971 DOI: 10.21315/mjms2017.24.5.5
    Background: Synthetic biology is emerging as a viable alternative for the production of recombinant antigens for diagnostic applications. It offers a safe alternative for the synthesis of antigenic principles derived from organisms that pose a high biological risk.

    Methods: Here, we describe an enzyme-linked immunosorbent assay (ELISA) using the synthetic recombinant LipL32 (rLipL32) protein expressed in Escherichia coli for the detection of Leptospira-specific antibodies in human serum samples. The rLipL32-based ELISA was compared with a microscopic agglutination test (MAT), which is currently used as the gold standard for the diagnosis of leptospirosis.

    Results: Our results showed that all the MAT-positive serum samples were positive for Leptospira-specific IgG in an ELISA, while 65% (n = 13) of these samples were also positive for Leptospira-specific IgM. In the MAT-negative serum samples, 80% and 55% of the samples were detected as negative by an ELISA for Leptospira-specific IgM and IgG, respectively.

    Conclusion: An ELISA using the synthetic rLipL32 antigen was able to distinguish Leptospira-specific IgM (sensitivity 65% and specificity 80%) and IgG (sensitivity 100% and specificity 55%) in human serum samples and has the potential to serve as a rapid diagnostic test for leptospirosis.

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