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  1. Chua AS, Keeling PW
    World J Gastroenterol, 2006 May 07;12(17):2688-93.
    PMID: 16718754 DOI: 10.3748/wjg.v12.i17.2688
    Functional dyspepsia (FD) is a common disorder of yet uncertain etiology. Dyspeptic symptoms are usually meal related and suggest an association to gastrointestinal (GI) sensorimotor dysfunction. Cholecystokinin (CCK) is an established brain-gut peptide that plays an important regulatory role in gastrointestinal function. It inhibits gastric motility and emptying via a capsaicin sensitive vagal pathway. The effects on emptying are via its action on the proximal stomach and pylorus. CCK is also involved in the regulation of food intake. It is released in the gut in response to a meal and acts via vagal afferents to induce satiety. Furthermore CCK has also been shown to be involved in the pathogenesis of panic disorder, anxiety and pain. Other neurotransmitters such as serotonin and noradrenaline may be implicated with CCK in the coordination of GI activity. In addition, intravenous administration of CCK has been observed to reproduce the symptoms in FD and this effect can be blocked both by atropine and loxiglumide (CCK-A antagonist). It is possible that an altered response to CCK may be responsible for the commonly observed gastric sensorimotor dysfunction, which may then be associated with the genesis of dyspeptic symptoms.
  2. Chua A, Yean CY, Ravichandran M, Lim B, Lalitha P
    Biosens Bioelectron, 2011 May 15;26(9):3825-31.
    PMID: 21458979 DOI: 10.1016/j.bios.2011.02.040
    Treating patients with infectious diseases relies heavily on rapid and proper diagnosis. Molecular detection such as PCR has become increasingly important and efforts have been made to simplify these detection methods. This study reports the development of a glass fibre-based lateral flow DNA biosensor that uses capture reagents coupled to carrier beads and detector reagent bioconjugated to gold nanoparticles, for the detection of foodborne pathogen, Vibrio cholerae. The DNA biosensor contains a test line which captures target PCR amplicons, an internal amplification control (IC) line which captures IC amplicons and a control line which acts as membrane control to validate the functionality of this device. The test line captures biotin labelled DNA, while the IC line captures digoxigenin labelled DNA. The detector reagent recognizes the fluorescein haptens of the amplified DNA and produces visual red lines. Scanning electron microscopy (SEM) studies performed indicated that the capture reagents remained relatively immobile within the matrix of the membrane even after binding of the detector reagent. The DNA biosensor recorded a limit of detection (LoD) of 5 ng of target DNA. A clinical evaluation was carried out with 174 strains of V. cholerae and non V. cholerae bacteria and the DNA biosensor recorded 100% for both sensitivity and specificity when compared to conventional agarose gel detection of DNA. Thus it is a viable alternative to agarose gel analysis and is easy-to-use, disposable and do not require any specialized equipment and use of carcinogenic chemicals.
  3. Ong YH, Chua AS, Lee BP, Ngoh GC
    Water Sci Technol, 2013;67(2):340-6.
    PMID: 23168633 DOI: 10.2166/wst.2012.552
    To date, little information is known about the operation of the enhanced biological phosphorus removal (EBPR) process in tropical climates. Along with the global concerns on nutrient pollution and the increasing array of local regulatory requirements, the applicability and compliance accountability of the EBPR process for sewage treatment in tropical climates is being evaluated. A sequencing batch reactor (SBR) inoculated with seed sludge from a conventional activated sludge (CAS) process was successfully acclimatized to EBPR conditions at 28 °C after 13 days' operation. Enrichment of Candidatus Accumulibacter phosphatis in the SBR was confirmed through fluorescence in situ hybridization (FISH). The effects of operational pH and influent C:P ratio on EBPR were then investigated. At pH 7 or pH 8, phosphorus removal rates of the EBPR processes were relatively higher when operated at C:P ratio of 3 than C:P ratio of 10, with 0.019-0.020 and 0.011-0.012 g-P/g-MLVSS•day respectively. One-year operation of the 28 °C EBPR process at C:P ratio of 3 and pH 8 demonstrated stable phosphorus removal rate of 0.020 ± 0.003 g-P/g-MLVSS•day, corresponding to effluent with phosphorus concentration <0.5 mg/L. This study provides the first evidence on good EBPR activity at relatively high temperature, indicating its applicability in a tropical climate.
  4. Dhillon VS, Deo P, Chua A, Thomas P, Fenech M
    J Gerontol A Biol Sci Med Sci, 2022 Feb 03;77(2):243-249.
    PMID: 34508574 DOI: 10.1093/gerona/glab264
    Significant alterations in sleep duration and/or quality of sleep become more pronounced as people get older. Poor sleep in elderly people is associated with adverse health outcomes and cellular aging. We examined the relationship between telomere length (TL) and sleep duration, Health Promotion Index (HPI), and tested whether the presence of Apolipoprotein-E4 (ApoE-ε4) allele affects both sleep and TL. The present study was carried out in 174 healthy participants (21% male; mean age 53.79 years) from South Australia. Lymphocyte TL was measured by real-time quantitative PCR (qPCR) and ApoE genotype was determined by TaqMan assay. HPI was calculated from a questionnaire regarding 8 lifestyle habits, including sleeping hours. Multivariate regression analysis was used to establish these associations adjusted for specified confounders. TL was found to be inversely associated with age (r = -0.199; p = .008) and body mass index (r = -0.121; p = .11), and was significantly shorter in participants who slept for less than 7 hours (p = .001) relative to those sleeping ≥7 hours. TL was positively correlated with HPI (r = 0.195; p = .009). ApoE-ε4 allele carriers who slept for less than 7 hours had shortest TL (p = .01) compared to noncarriers. Plasma soluble receptor for advanced glycation end product (sRAGE) level was significantly (p = .001) lower in individuals who sleep less than 7 hours and ApoE-ε4 carriers. Our results suggest that inadequate sleep duration or poor HPI is associated with shorter TL in cognitively normal people and that carriage of APOE-ε4 genotype may influence the extent of these effects.
  5. Hilmi I, Jaya F, Chua A, Heng WC, Singh H, Goh KL
    J Crohns Colitis, 2015 May;9(5):404-9.
    PMID: 25744112 DOI: 10.1093/ecco-jcc/jjv039
    Inflammatory bowel disease [IBD] is known to be rare in the Asia Pacific region but epidemiological studies are scarce.
  6. Hilmi I, Singh R, Ganesananthan S, Yatim I, Radzi M, Chua AB, et al.
    J Dig Dis, 2009 Feb;10(1):15-20.
    PMID: 19236542 DOI: 10.1111/j.1751-2980.2008.00357.x
    To establish the clinical course of ulcerative colitis (UC) in the Malaysian population, comparing the three major ethnic groups: Malay, Chinese and Indian.
  7. Goh KL, Cutler A, Chua AB, Ding RP, Kandasami P, Mazlam MZ, et al.
    J Gastroenterol Hepatol, 1999 Jan;14(1):32-8.
    PMID: 10029275
    The aim of the present study was to determine the cost-efficiency of different duodenal ulcer disease treatment practices in Malaysia. Six Malaysian gastroenterologists met to discuss the direct costs related to Helicobacter pylori (HP) eradication treatment. Five treatment strategies were compared: (i) histamine H2 receptor antagonists (H2RA), acid suppression therapy for 6 weeks followed by maintenance therapy as needed; (ii) bismuth triple + proton pump inhibitor (PPI), bismuth (120 mg, q.i.d.), metronidazole (400 mg; t.i.d.), tetracycline (500 mg, q.i.d.) for 7 days and PPI, b.i.d., for 7 days; (iii) OAC, omeprazole (20 mg, b.i.d.), amoxycillin (1000 mg, b.i.d.) and clarithromycin (500 mg, b.i.d.) for 7 days; (iv) OMC, omeprazole (20mg, b.i.d.), metronidazole (400mg, b.i.d.) and clarithromycin (500 mg, b.i.d.) for 7 days; and (v) OAM, omeprazole (20 mg, b.i.d.), amoxycillin (1000 mg, b.i.d.) and metronidazole (400 mg, b.i.d.) for 7 days. A decision tree model was created to determine which therapy would be the most cost-effective. The model considered eradication rates, resistance to anti-microbial agents, compliance and cost implications of treatment regimens, physician visits and ulcer recurrences during a 1 year time period assumption. The H2RA maintenance therapy was the most expensive treatment at Malaysian Ringgit (MR) 2335, followed by bismuth triple therapy (MR 1839), OMC (MR 1786), OAM (MR 1775) and OAC, being the most cost-effective therapy, at MR 1679. In conclusion, HP eradication therapy is superior to H2RA maintenance therapy in the treatment of duodenal ulcer disease. Of the HP eradication regimens, OAC is the most cost-effective.
  8. How SW, Lim SY, Lim PB, Aris AM, Ngoh GC, Curtis TP, et al.
    Water Sci Technol, 2018 May;77(9-10):2274-2283.
    PMID: 29757179 DOI: 10.2166/wst.2018.143
    Intensive aeration for nitrification is a major energy consumer in sewage treatment plants (STPs). Low-dissolved-oxygen (low-DO) nitrification has the potential to lower the aeration demand. However, the applicability of low-DO nitrification in the tropical climate is not well-understood. In this study, the potential of low-DO nitrification in tropical setting was first examined using batch kinetic experiments. Subsequently, the performance of low-DO nitrification was investigated in a laboratory-scale sequential batch reactor (SBR) for 42 days using real tropical sewage. The batch kinetic experiments showed that the seed sludge has a relatively high oxygen affinity. Thus, the rate of nitrification was not significantly reduced at low DO concentrations (0.5 mg/L). During the operation of the low-DO nitrification SBR, 90% of NH4-N was removed. The active low-DO nitrification was mainly attributed to the limited biodegradable organics in the sewage. Fluorescence in-situ hybridisation and 16S rRNA amplicon sequencing revealed the nitrifiers were related to Nitrospira genus and Nitrosomonadaceae family. Phylogenetic analysis suggests 47% of the operational taxonomic units in Nitrospira genus are closely related to a comammox bacteria. This study has demonstrated active low-DO nitrification in tropical setting, which is a more sustainable process that could significantly reduce the energy footprint of STPs.
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