Displaying publications 1 - 20 of 62 in total

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  1. Abdullah N, Yuzir A, Curtis TP, Yahya A, Ujang Z
    Bioresour Technol, 2013 Jan;127:181-7.
    PMID: 23131639 DOI: 10.1016/j.biortech.2012.09.047
    Understanding the relationship between microbial community and mechanism of aerobic granulation could enable wider applications of granules for high-strength wastewater treatment. The majority of granulation studies principally determine the engineering aspects of granules formation with little emphasis on the microbial diversity. In this study, three identical reactors namely R1, R2 and R3 were operated using POME at volumetric loadings of 1.5, 2.5 and 3.5 kg COD m(-3) d(-1), respectively. Aeration was provided at a volumetric flow rate of 2.5 cms(-1). Aerobic granules were successfully developed in R2 and R3 while bioflocs dominated R1 until the end of experiments. Fractal dimension (D(f)) averaged at 1.90 suggesting good compactness of granules. The PCR-DGGE results indicated microbial evolutionary shift throughout granulation despite different operating OLRs based on decreased Raup and Crick similarity indices upon mature granule formation. The characteristics of aerobic granules treating high strength agro-based wastewater are determined at different volumetric loadings.
  2. Sharif R, Thomas P, Zalewski P, Fenech M
    Mol Nutr Food Res, 2015 Jun;59(6):1200-12.
    PMID: 25755079 DOI: 10.1002/mnfr.201400784
    An increased intake of Zinc (Zn) may reduce the risk of degenerative diseases but may prove to be toxic if taken in excess. This study aimed to investigate whether zinc carnosine supplement can improve Zn status, genome stability events, and Zn transporter gene expression in an elderly (65-85 years) South Australian cohort with low plasma Zn levels.
  3. Thomas P, Lai CW, Johan MR
    Chemosphere, 2022 Dec;308(Pt 1):136214.
    PMID: 36057345 DOI: 10.1016/j.chemosphere.2022.136214
    In this paper, we present the synthesis of C@Fe3O4-MoO3 binary composite were prepared through the facile hydrothermal process. The ultrasonic aided adsorption efficacy was evaluated by studying triphenylmethane dye's adsorption potential. The ultrasonic aided adsorption capacity towards crystal violet was 993.6 mg/g, which is remarkably higher and best fitted with the Langmuir isotherm model and followed pseudo-second-order kinetics. The electrochemical studies working electrode have been prepared with 80 wt% active material, 10 wt% carbon black, and 10% polyvinylidene difluoride to evaluate energy storage characteristics. The C@Fe3O4-MoO3 demonstrated an excellent specific capacitance of 40.94 F/g with better retention and stability, making it a potential cathode material for next-generation electrochemical energy storage devices.
  4. Thomas P, Lai CW, Johan MR
    Environ Res, 2022 Sep;212(Pt C):113417.
    PMID: 35569532 DOI: 10.1016/j.envres.2022.113417
    The toxic wastewater effluents from textile dyes have been a significant environmental threat worldwide in recent decades. Against this backdrop, this study investigates the performance of C@Fe3O4-MoO3-rGO as a sonoadsorbent to ameliorate crystal violet (CV) dye from the aqua matrix and further explores its potential as an electrode in supercapacitor applications. The phase purity, crystal structure, surface morphology, thermal stability and magnetic behaviour characteristics of the composite were studied using various characterisation techniques such as powder X-ray diffraction (XRD), Raman Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), Thermogravimetric analysis (TGA) and Vibrating-sample magnetometry (VSM). From the Langmuir isotherm model, the synthesised sonoadsorbent exhibited a maximum adsorption capacity of 1664.26 mg/g for crystal violet, which is remarkably high. Further, to its inherited magnetic characteristics, the composite can be easily separated from the solution by using an external magnet. Furthermore, the working electrode was synthesised with 80% active material, 10% carbon black, and 10% polyvinylidene difluoride to investigate its suitability in supercapacitor applications. The C@Fe3O4-MoO3-rGO composite exhibited an excellent capacitance value of 180.36 F/g with commendable cycling stability, making it suitable as a potential cathode material for the next generation supercapacitors.
  5. How SW, Chua ASM, Ngoh GC, Nittami T, Curtis TP
    Sci Total Environ, 2019 Nov 25;693:133526.
    PMID: 31376760 DOI: 10.1016/j.scitotenv.2019.07.332
    Many wastewater treatment plants (WWTPs) operating in biological nitrogen removal activated sludge process in the tropics are facing the pressure of increasingly stringent effluent standards while seeking solutions to reduce the plants' energy consumption and operating cost. This study investigated the feasibility of applying low-dissolved oxygen (low-DO) nitrification and utilizing slowly-biodegradable chemical oxygen demand (sbCOD) for denitrification, which helps to reduce energy usage and operating cost in treating low soluble COD-to-nitrogen tropical wastewater. The tropical wastewater was first characterized using wastewater fractionation and respirometry batch tests. Then, a lab-scale sequencing batch reactor (SBR) was operated to evaluate the long-term stability of low-DO nitrification and utilizing sbCOD for denitrification in an anoxic-oxic (AO) process treating tropical wastewater. The wastewater fractionation experiment revealed that particulate settleable solids (PSS) in the wastewater provided slowly-biodegradable COD (sbCOD), which made up the major part (51 ± 10%) of the total COD. The PSS hydrolysis rate constant at tropical temperature (30 °C) was 2.5 times higher than that at 20 °C, suggesting that sbCOD may be utilized for denitrification. During the SBR operation, high nitrification efficiency (93 ± 6%) was attained at low-DO condition (0.9 ± 0.1 mg O2/L). Utilizing sbCOD for post-anoxic denitrification in the SBR reduced the effluent nitrate concentration. Quantitative polymerase chain reaction, 16S rRNA amplicon sequencing and fluorescence in-situ hybridization revealed that the genus Nitrospira was a dominant nitrifier. 16S rRNA amplicon sequencing result suggested that 50% of the Nitrospira-related operational taxonomic units were affiliated with comammox, which may imply that the low-DO condition and the warm wastewater promoted their growth. The nitrogen removal in a tropical AO process was enhanced by incorporating low-DO nitrification and utilizing sbCOD for post-anoxic denitrification, which contributes to an improved energy sustainability of WWTPs.
  6. Niemann J, Gopalakrishnan S, Yamaguchi N, Ramos-Madrigal J, Wales N, Gilbert MTP, et al.
    iScience, 2021 Jan 22;24(1):101904.
    PMID: 33364590 DOI: 10.1016/j.isci.2020.101904
    The Japanese or Honshū wolf was one the most distinct gray wolf subspecies due to its small stature and endemicity to the islands of Honshū, Shikoku, and Kyūshū. Long revered as a guardian of farmers and travellers, it was persecuted from the 17th century following a rabies epidemic, which led to its extinction in the early 20th century. To better understand its evolutionary history, we sequenced the nuclear genome of a 19th century Honshū wolf specimen to an average depth of coverage of 3.7✕. We find Honshū wolves were closely related to a lineage of Siberian wolves that were previously believed to have gone extinct in the Late Pleistocene, thereby extending the survival of this ancient lineage until the early 20th century. We also detected significant gene flow between Japanese dogs and the Honshū wolf, corroborating previous reports on Honshū wolf dog interbreeding.
  7. How SW, Nittami T, Ngoh GC, Curtis TP, Chua ASM
    Chemosphere, 2020 Nov;259:127444.
    PMID: 32640378 DOI: 10.1016/j.chemosphere.2020.127444
    In this study, we assessed and optimized a low-dissolved-oxygen oxic-anoxic (low-DO OA) process to achieve a low-cost and sustainable solution for wastewater treatment systems in the developing tropical countries treating low chemical oxygen demand-to-nitrogen ratio (COD/N) wastewater. The low-DO OA process attained complete ammonia removal and the effluent nitrate nitrogen (NO3-N) was below 0.3 mg/L. The recommended hydraulic retention time and sludge retention time (SRT) were 16 h and 20 days, respectively. The 16S rRNA sequencing data revealed that long SRT (20 days) encouraged the growth of nitrite-oxidizing bacteria (NOB) affiliated with "Candidatus Nitrospira defluvii". Comammox made up 10-20% of the Nitrospira community. NOB and comammox related to Nitrospira were enriched at long SRT (20 days) to achieve good low-DO nitrification performance. The low-DO OA process was efficient and has simpler design than conventional processes, which are keys for sustainable wastewater treatment systems in the developing countries treating low COD/N wastewater.
  8. Parvar H, Sculthorpe-Petley L, Satel J, Boshra R, D'Arcy RC, Trappenberg TP
    Brain Inform, 2015 Mar;2(1):1-12.
    PMID: 27747499
    Event-related potentials (ERPs) are tiny electrical brain responses in the human electroencephalogram that are typically not detectable until they are isolated by a process of signal averaging. Owing to the extremely smallsize of ERP components (ranging from less than 1 μV to tens of μV), compared to background brain rhythms, statistical analyses of ERPs are predominantly carried out in groups of subjects. This limitation is a barrier to the translation of ERP-based neuroscience to applications such as medical diagnostics. We show here that support vector machines (SVMs) are a useful method to detect ERP components in individual subjects with a small set of electrodes and a small number of trials for a mismatch negativity (MMN) ERP component. Such a reduced experiment setup is important for clinical applications. One hundred healthy individuals were presented with an auditory pattern containing pattern-violating deviants to evoke the MMN. Two-class SVMs were then trained to classify averaged ERP waveforms in response to the standard tone (tones that match the pattern) and deviant tone stimuli (tones that violate the pattern). The influence of kernel type, number of epochs, electrode selection, and temporal window size in the averaged waveform were explored. When using all electrodes, averages of all available epochs, and a temporal window from 0 to 900-ms post-stimulus, a linear SVM achieved 94.5 % accuracy. Further analyses using SVMs trained with narrower, sliding temporal windows confirmed the sensitivity of the SVM to data in the latency range associated with the MMN.
  9. Drinkwater R, Schnell IB, Bohmann K, Bernard H, Veron G, Clare E, et al.
    Mol Ecol Resour, 2019 Jan;19(1):105-117.
    PMID: 30225935 DOI: 10.1111/1755-0998.12943
    The application of high-throughput sequencing (HTS) for metabarcoding of mixed samples offers new opportunities in conservation biology. Recently, the successful detection of prey DNA from the guts of leeches has raised the possibility that these, and other blood-feeding invertebrates, might serve as useful samplers of mammals. Yet little is known about whether sympatric leech species differ in their feeding preferences, and whether this has a bearing on their relative suitability for monitoring local mammalian diversity. To address these questions, we collected spatially matched samples of two congeneric leech species Haemadipsa picta and Haemadipsa sumatrana from lowland rainforest in Borneo. For each species, we pooled ~500 leeches into batches of 10 individuals, performed PCR to target a section of the mammalian 16S rRNA locus and undertook sequencing of amplicon libraries using an Illumina MiSeq. In total, we identified sequences from 14 mammalian genera, spanning nine families and five orders. We found greater numbers of detections, and higher diversity of OTUs, in H. picta compared with H. sumatrana, with rodents only present in the former leech species. However, comparison of samples from across the landscape revealed no significant difference in mammal community composition between the leech species. We therefore suggest that H. picta is the more suitable iDNA sampler in this degraded Bornean forest. We conclude that the choice of invertebrate sampler can influence the detectability of different mammal groups and that this should be accounted for when designing iDNA studies.
  10. Jahari PNS, Abdul Malik NF, Shamsir MS, Gilbert MTP, Mohd Salleh F
    Data Brief, 2020 Aug;31:105721.
    PMID: 32490085 DOI: 10.1016/j.dib.2020.105721
    The spotted seahorse, Hippocampus kuda population is exponentially decreasing globally due to habitat loss contributed by massive coastal urbanization as well as its large exploitation for Chinese herbal medicine. Genomic data would be highly useful to improve biomonitoring of seahorse populations in Malaysia via the usage of non-invasive approaches such as water environmental DNA. Here we report the first complete mitogenome of two H. kuda individuals originating from Malaysia, generated using BGISEQ-500RS sequencer. The lengths of both mitogenomes are 16,529bp, consisting of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The overall base composition was 32.46% for A, 29.40% for T, 14.73% for G and 23.41% for C with AT rich features (61.86%). The gene organization of Malaysian H. kuda were similar to that of most teleost species. A phylogenetic analysis of the genome against mtDNA data from other Hippocampus species showed that Malaysian H. kuda samples clustered with H. capensis, H. reidi and H. kuda. Notably however, analysis of the data using BLASTn revealed they had 99.18% similarity to H. capensis, and only 97.66% to H. kuda and H. reidi, which are all part of the unresolved H. kuda complex. The mitogenomes are deposited in Genbank under the accession number MT221436 (HK1) and MT221436 (HK2).
  11. Djojodibroto RD, Thomas PT, Kana KT, Hla M
    Med J Malaysia, 2014 Apr;69(2):60-3.
    PMID: 25241813 MyJurnal
    Some diseases may underlie finger clubbing. However, there is a dearth of information about early stage of finger clubbing because only few researchers have shown interest in it. We determined the Digital Index of normal, healthy subjects by using thread and manual Vernier calipers, the time used for the procedure, and its interrater reliability. The value of Digital Index was 8.86 ± 0.29 (Mean ± SD) with a range of 8.15 to 9.41. Interrater reliability was excellent with Pearson's correlation coefficient of 0.966. Overall, the time taken to measure the Digital Index ranged from 21.93 to 68.80 minutes with an average of 35.97 ± 9.16 (Mean ± SD). Determining Digital Index need much time, but this can be overcome if we use Digital Index Quantitator (DIQ). Availability of DIQ in the hospital wards will be of much benefit. DIQ can also be used to accurately quantify the progression or regression of the clubbing process. This article proves that we need morphometry of digital clubbing as well as the correlation of the physical sign of clubbing with Digital Index.
  12. Deo P, Dhillon VS, Thomas P, Fenech M
    PMID: 34628492 DOI: 10.1093/gerona/glab307
    Red blood cell (RBC) fatty acids status is used as a biomarker of dietary intake of fats however, there is still a paucity of evidence regarding individual fatty acids and modulation of endogenous advanced glycation end-product (AGE) levels. Due to membrane PUFA being a well-known target for peroxidation, we hypothesized that cellular PUFAs are positively associated with circulatory N ε-carboxymethyllysine (CML) that is also influenced by glyoxal (GO) levels in healthy cohorts. To test this, we investigated the association between RBC fatty acids and circulatory AGEs biomarkers in healthy individuals. The results showed a negative association between saturated fatty acids (SFA) and CML and stepwise multivariate regression analysis indicated stearic acid was negatively associated with CML levels (β = -0.200, p=0.008) after adjusting for age, BMI, and gender. In addition, stearic acid: palmitic acid ratio was also negatively correlated with plasma concentrations of CML (rp= -0.191, p = 0.012) and glucose (rp= -0.288, p = 0.0001). Polyunsaturated fatty acids (PUFA) showed a positive association with CML levels particularly, docosapentaenoic acid, γ-Linolenic acid, arachidonic acid, and docosadienoic acid. However, these associations were not evident after the multiple regression analysis adjusted for age, BMI, and gender. A strong negative correlation (rp= -0.98, p< 0.0001) between total PUFA and total SFA was observed. Furthermore, the SFA:PUFA ratio was inversely correlated with CML (rp= -0.227, p< 0.003). Overall, this study indicates that different fats and their combinations may influence the formation of AGEs and that carefully controlled interventions are required to further test this hypothesis.
  13. 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.
  14. Sculthorpe-Petley L, Liu C, Hajra SG, Parvar H, Satel J, Trappenberg TP, et al.
    J Neurosci Methods, 2015 Apr 30;245:64-72.
    PMID: 25701685 DOI: 10.1016/j.jneumeth.2015.02.008
    Event-related potentials (ERPs) may provide a non-invasive index of brain function for a range of clinical applications. However, as a lab-based technique, ERPs are limited by technical challenges that prevent full integration into clinical settings.
  15. Zepeda Mendoza ML, Roggenbuck M, Manzano Vargas K, Hansen LH, Brunak S, Gilbert MTP, et al.
    Acta Vet Scand, 2018 Oct 11;60(1):61.
    PMID: 30309375 DOI: 10.1186/s13028-018-0415-3
    BACKGROUND: Vultures have adapted the remarkable ability to feed on carcasses that may contain microorganisms that would be pathogenic to most other animals. The holobiont concept suggests that the genetic basis of such adaptation may not only lie within their genomes, but additionally in their associated microbes. To explore this, we generated shotgun DNA sequencing datasets of the facial skin and large intestine microbiomes of the black vulture (Coragyps atratus) and the turkey vulture (Cathartes aura). We characterized the functional potential and taxonomic diversity of their microbiomes, the potential pathogenic challenges confronted by vultures, and the microbial taxa and genes that could play a protective role on the facial skin and in the gut.

    RESULTS: We found microbial taxa and genes involved in diseases, such as dermatitis and pneumonia (more abundant on the facial skin), and gas gangrene and food poisoning (more abundant in the gut). Interestingly, we found taxa and functions with potential for playing beneficial roles, such as antilisterial bacteria in the gut, and genes for the production of antiparasitics and insecticides on the facial skin. Based on the identified phages, we suggest that phages aid in the control and possibly elimination, as in phage therapy, of microbes reported as pathogenic to a variety of species. Interestingly, we identified Adineta vaga in the gut, an invertebrate that feeds on dead bacteria and protozoans, suggesting a defensive predatory mechanism. Finally, we suggest a colonization resistance role through biofilm formation played by Fusobacteria and Clostridia in the gut.

    CONCLUSIONS: Our results highlight the importance of complementing genomic analyses with metagenomics in order to obtain a clearer understanding of the host-microbial alliance and show the importance of microbiome-mediated health protection for adaptation to extreme diets, such as scavenging.

  16. Jahari PNS, Mohd Azman S, Munian K, Ahmad Ruzman NH, Shamsir MS, Richter SR, et al.
    Mitochondrial DNA B Resour, 2020 Aug 26;5(3):3004-3006.
    PMID: 33458034 DOI: 10.1080/23802359.2020.1797583
    The mitogenome of a plantain squirrel, Callosciurus notatus, collected from Bukit Tarek Forest Reserve (Extension), Selangor, Malaysia was sequenced using BGISEQ-500RS technology. The 16,582 bp mitogenome consists of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 control region. A phylogenetic and BLASTn analysis against other available datasets showed that the mitogenome matched with 99.49% similarity to a previously published C. notatus mitogenome from Peninsular Malaysia. However, it also diverged by nearly 8% (92.24% match) from a second previously published mitogenome for the same species, sampled in East Kalimantan, Indonesia. This suggests a difference in landscape features between both localities might affect its genetic connectivity.
  17. Drinkwater R, Jucker T, Potter JHT, Swinfield T, Coomes DA, Slade EM, et al.
    Mol Ecol, 2021 07;30(13):3299-3312.
    PMID: 33171014 DOI: 10.1111/mec.15724
    The application of metabarcoding to environmental and invertebrate-derived DNA (eDNA and iDNA) is a new and increasingly applied method for monitoring biodiversity across a diverse range of habitats. This approach is particularly promising for sampling in the biodiverse humid tropics, where rapid land-use change for agriculture means there is a growing need to understand the conservation value of the remaining mosaic and degraded landscapes. Here we use iDNA from blood-feeding leeches (Haemadipsa picta) to assess differences in mammalian diversity across a gradient of forest degradation in Sabah, Malaysian Borneo. We screened 557 individual leeches for mammal DNA by targeting fragments of the 16S rRNA gene and detected 14 mammalian genera. We recorded lower mammal diversity in the most heavily degraded forest compared to higher quality twice logged forest. Although the accumulation curves of diversity estimates were comparable across these habitat types, diversity was higher in twice logged forest, with more taxa of conservation concern. In addition, our analysis revealed differences between the community recorded in the heavily logged forest and that of the twice logged forest. By revealing differences in mammal diversity across a human-modified tropical landscape, our study demonstrates the value of iDNA as a noninvasive biomonitoring approach in conservation assessments.
  18. How SW, Sin JH, Wong SYY, Lim PB, Mohd Aris A, Ngoh GC, et al.
    Water Sci Technol, 2020 Jan;81(1):71-80.
    PMID: 32293590 DOI: 10.2166/wst.2020.077
    Many developing countries, mostly situated in the tropical region, have incorporated a biological nitrogen removal process into their wastewater treatment plants (WWTPs). Existing wastewater characteristic data suggested that the soluble chemical oxygen demand (COD) in tropical wastewater is not sufficient for denitrification. Warm wastewater temperature (30 °C) in the tropical region may accelerate the hydrolysis of particulate settleable solids (PSS) to provide slowly-biodegradable COD (sbCOD) for denitrification. This study aimed to characterize the different fractions of COD in several sources of low COD-to-nitrogen (COD/N) tropical wastewater. We characterized the wastewater samples from six WWTPs in Malaysia for 22 months. We determined the fractions of COD in the wastewater by nitrate uptake rate experiments. The PSS hydrolysis kinetic coefficients were determined at tropical temperature using an oxygen uptake rate experiment. The wastewater samples were low in readily-biodegradable COD (rbCOD), which made up 3-40% of total COD (TCOD). Most of the biodegradable organics were in the form of sbCOD (15-60% of TCOD), which was sufficient for complete denitrification. The PSS hydrolysis rate was two times higher than that at 20 °C. The high PSS hydrolysis rate may provide sufficient sbCOD to achieve effective biological nitrogen removal at WWTPs in the tropical region.
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