Displaying all 7 publications

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  1. Ho CL, Lee WK, Lim EL
    Genomics, 2018 03;110(2):124-133.
    PMID: 28890206 DOI: 10.1016/j.ygeno.2017.09.003
    Agar and agarose have wide applications in food and pharmaceutical industries. Knowledge on the genome of red seaweeds that produce them is still lacking. To fill the gap in genome analyses of these red algae, we have sequenced the nuclear and organellar genomes of an agarophyte, Gracilaria changii. The partial nuclear genome sequence of G. changii has a total length of 35.8Mb with 10,912 predicted protein coding sequences. Only 39.4% predicted proteins were found to have significant matches to protein sequences in SwissProt. The chloroplast genome of G. changii is 183,855bp with a total of 201 open reading frames (ORFs), 29 tRNAs and 3 rRNAs predicted. Five genes: ssrA, leuC and leuD CP76_p173 (orf139) and pbsA were absent in the chloroplast genome of G. changii. The genome information is valuable in accelerating functional studies of individual genes and resolving evolutionary relationship of red seaweeds.
  2. Lim EL, Ngeow WC, Lim D
    Braz Oral Res, 2017 Nov 27;31:e97.
    PMID: 29185606 DOI: 10.1590/1807-3107bor-2017.vol31.0097
    The objective of this study was to measure the topographic thickness of the lateral wall of the maxillary sinus in selected Asian populations. Measurements were made on the lateral walls of maxillary sinuses recorded using CBCT in a convenient sample of patients attending an Asian teaching hospital. The points of measurement were the intersections between the axes along the apices of the canine, first premolar, and second premolar and along the mesiobuccal and distobuccal apices of the first and second molars and horizontal planes 10 mm, 20 mm, 30 mm and 40 mm beneath the orbital floor. The CBCT images of 109 patients were reviewed. The mean age of the patients was 33.0 (SD 14.8) years. Almost three quarters (71.8%) of the patients were male. The mean bone thickness decreased beginning at the 10-mm level and continuing to 40 mm below the orbital floor. Few canine regions showed encroachment of the maxillary sinus. The thickness of the buccal wall gradually increased from the canine region (where sinus encroachment of the canine region was present) to the first molar region, after which it decreased to the thickness observed at the canine region. The buccal wall of the maxillary sinus became thicker anteroposteriorly, except in the region of the second molar, and thinner superoinferiorly. These changes will affect the approach used to osteotomize the lateral sinus wall for oral surgery and for the sinus lift procedure.
  3. Lim EL, Siow RS, Abdul Rahim R, Ho CL
    Mar. Biotechnol., 2016 Apr;18(2):189-200.
    PMID: 26631182 DOI: 10.1007/s10126-015-9680-6
    Many bacterial epiphytes of agar-producing seaweeds secrete agarase that degrade algal cell wall matrix into oligoagars which elicit defense-related responses in the hosts. The molecular defense responses of red seaweeds are largely unknown. In this study, we surveyed the defense-related transcripts of an agarophyte, Gracilaria changii, treated with β-agarase through next generation sequencing (NGS). We also compared the defense responses of seaweed elicited by agarase with those elicited by an agarolytic bacterium isolated from seaweed, by profiling the expression of defense-related genes using quantitative reverse transcription real-time PCR (qRT-PCR). NGS detected a total of 391 differentially expressed genes (DEGs) with a higher abundance (>2-fold change with a p value <0.001) in the agarase-treated transcriptome compared to that of the non-treated G. changii. Among these DEGs were genes related to signaling, bromoperoxidation, heme peroxidation, production of aromatic amino acids, chorismate, and jasmonic acid. On the other hand, the genes encoding a superoxide-generating NADPH oxidase and related to photosynthesis were downregulated. The expression of these DEGs was further corroborated by qRT-PCR results which showed more than 90 % accuracy. A comprehensive analysis of their gene expression profiles between 1 and 24 h post treatments (hpt) revealed that most of the genes analyzed were consistently upregulated or downregulated by both agarase and agarolytic bacterial treatments, indicating that the defense responses induced by both treatments are highly similar except for genes encoding vanadium bromoperoxidase and animal heme peroxidase. Our study has provided the first glimpse of the molecular defense responses of G. changii to agarase and agarolytic bacterial treatments.
  4. Lim EL, Yap CC, Jumali MHH, Teridi MAM, Teh CH
    Nanomicro Lett, 2018;10(2):27.
    PMID: 30393676 DOI: 10.1007/s40820-017-0182-0
    Perovskite solar cells (PSCs) have raised research interest in scientific community because their power conversion efficiency is comparable to that of traditional commercial solar cells (i.e., amorphous Si, GaAs, and CdTe). Apart from that, PSCs are lightweight, are flexible, and have low production costs. Recently, graphene has been used as a novel material for PSC applications due to its excellent optical, electrical, and mechanical properties. The hydrophobic nature of graphene surface can provide protection against air moisture from the surrounding medium, which can improve the lifetime of devices. Herein, we review recent developments in the use of graphene for PSC applications as a conductive electrode, carrier transporting material, and stabilizer material. By exploring the application of graphene in PSCs, a new class of strategies can be developed to improve the device performance and stability before it can be commercialized in the photovoltaic market in the near future.
  5. Lim EL, Seah TC, Koe XF, Wahab HA, Adenan MI, Jamil MF, et al.
    Toxicol In Vitro, 2013 Mar;27(2):812-24.
    PMID: 23274770 DOI: 10.1016/j.tiv.2012.12.014
    CYP450 enzymes are key determinants in drug toxicities, reduced pharmacological effect and adverse drug reactions. Mitragynine, an euphoric compound was evaluated for its effects on the expression of mRNAs encoding CYP1A2, CYP2D6 and CYP3A4 and protein expression and resultant enzymatic activity. The mRNA and protein expression of CYP450 isoforms were carried out using an optimized multiplex qRT-PCR assay and Western blot analysis. CYP1A2 and CYP3A4 enzyme activities were evaluated using P450-Glo™ assays. The effects of mitragynine on human CYP3A4 protein expression were determined using an optimized hCYP3A4-HepG2 cell-based assay. An in silico computational method to predict the binding conformation of mitragynine to the active site of the CYP3A4 enzyme was performed and further validated using in vitro CYP3A4 inhibition assays. Mitragynine was found to induce mRNA and protein expression of CYP1A2. For the highest concentration of 25 μM, induction of mRNA was approximately 70% that of the positive control and was consistent with the increased CYP1A2 enzymatic activity. Thus, mitragynine is a significant in vitro CYP1A2 inducer. However, it appeared to be a weak CYP3A4 inducer at the transcriptional level and a weak CYP3A4 enzyme inhibitor. It is therefore, unlikely to have any significant clinical effects on CYP3A4 activity.
  6. Koe XF, Lim EL, Seah TC, Amanah A, Wahab HA, Adenan MI, et al.
    Food Chem. Toxicol., 2013 Oct;60:98-108.
    PMID: 23876819 DOI: 10.1016/j.fct.2013.07.030
    Drug metabolism involving cytochrome P450 (CYP) enzymes is a key determinant of significant drug interactions. Deoxyelephantopin was evaluated for its effects on the expression of mRNAs encoding CYP1A2, CYP2D6 and CYP3A4, and protein expression and resultant enzymatic activity. The mRNA and protein expression of cytochrome isoforms were carried out using an optimized multiplex qRT-PCR assay and Western blot analysis, respectively. Human CYP3A4 protein expression was determined using an optimized hCYP3A4-HepG2 cell-based assay and the enzymatic activity was evaluated using P450-Glo™ CYP3A4 assay. The molecular interaction and possible inhibition of deoxyelephantopin of the CYP3A4 enzyme was determined in silico and further validated using substrate-specific CYP3A4 inhibition assays. Deoxyelephantopin produced no significant effect on the CYP1A2 and CYP2D6 mRNA and protein expression. However, it has a weak induction effect on CYP3A4 at the transcriptional level. In silico docking simulation showed that deoxyelephantopin has a weak interaction with CYP3A4 enzyme and it minimally affects the metabolism of CYP3A4 substrates. Deoxyelephantopin is not an in vitro CYP1A2 and CYP2D6 inducer. It is both a weak in vitro CYP3A4 inducer and inhibitor and is unlikely to elicit a clinically significant effect in human.
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