MyMedR

Displaying all 7 publications

Abstract:

Sort:

Time trends in upper gastrointestinal diseases and Helicobacter pylori infection in a multiracial Asian population--a 20-year experience over three time periods

Leow AH, Lim YY, Liew WC, Goh KL

Aliment Pharmacol Ther, 2016 Apr;43(7):831-7.
PMID: 26847417 DOI: 10.1111/apt.13550

Marked epidemiological changes in upper gastrointestinal diseases and Helicobacter pylori infection have taken place in the Asian Pacific region. In particular, differences with respect to race in the multiracial Asian population in Malaysia have been important and interesting.
Synergistic effect of graphene oxide/zinc oxide nanocomposites on polylactic acid-based active packaging film: Properties, release kinetics and antimicrobial efficiency

Liew WC, Muhamad II, Chew JW, Karim KJA

Int J Biol Macromol, 2023 Dec 31;253(Pt 6):127288.
PMID: 37813215 DOI: 10.1016/j.ijbiomac.2023.127288

Incorporating two different nanoparticles in nanocomposite films is promising as their synergistic effects could significantly enhance polymer performance. Our previous work conferred the remarkable antimicrobial (AM) properties of the polylactic acid (PLA)-based film using optimal formulations of synergistic graphene oxide (GO)/zinc oxide (ZnO) nanocomposites. This study further explores the release profile of GO/ZnO nanocomposite and their impact on the antimicrobial properties. A fixed 1.11 wt% GO and different ZnO concentrations were well dispersed in the PLA matrix. Increasing ZnO concentrations tended to increase agglomeration, as evident in rougher surfaces. Agglomeration inhibited water penetration, leading to a significant reduction in water permeability (46.3 %), moisture content (31.6 %) but an improvement in Young's Modulus (52.6 %). The overall and specific migration of GO/ZnO nanocomposites was found to be within acceptable limits. It is inferred that the release of Zn2+ ions followed pseudo-Fickian behavior with an initial burst effect. AM film with the highest concentration of ZnO (1.25 wt%) exhibited the highest inhibition rate against Escherichia coli (68.0 %), Bacillus cereus (66.5 %), Saccharomyces cerevisiae (70.9 %). Results suggest that GO/ZnO nanocomposites with optimal ZnO concentrations have the potential to serve as promising antimicrobial food packaging materials, offering enhanced barrier, antimicrobial properties and a controlled release system.
Fulltext Messages of the Newly Proposed Malaysian Dietary Guidelines (MDG): Do Adults in Kuala Lumpur Understand Them?

Norimah AK, Hwong CS, Liew WC, Ruzita AT, Siti Sa'adiah HN, Ismail MN

Malays J Nutr, 2010 Apr;16(1):113-23.
PMID: 22691858 MyJurnal

The Malaysian Dietary Guidelines (MDG) with eight key messages were first published in 1999. An updated version consisting of 14 key messages is being developed. The objective of this study was to evaluate the understanding of five key messages of the updated MDG among adults aged 18-59 years in Kuala Lumpur. A total of 773 adults comprising 330 Malays, 364 Chinese and 79 Indians were included in the study. A self-administrated questionnaire was used to obtain demographic data and to determine the level of understanding of key words and messages to be included in the new MDG. The results showed that 63% of the subjects were not aware of the existence of the MDG published in 1999. Overall, the understanding of the five messages in the updated MDG was moderate with a mean score of 60.0 ± 16.5. Between 52% to 93% of the subjects did not understand such key words as serving size, sedentary habits, blended vegetable oil and shortenings. The mean scores of understanding were significantly higher (p< 0.05) among the Chinese subjects (61.3 ± 17.8) than Malays (58.6 ± 14.2) and Indians (60.0 ± 18.9). The younger subjects (61.2 + 16.0) scored significantly (p< 0.05) higher than the older (58.7 ± 17.0) counterparts. There was also a significant association between the level of understanding of MDG with education level (p< 0.001) and occupational status (p< 0.001), respectively. This study suggests that some key words and messages in the updated MDG should be simplified to ensure that they are understood by Malaysians.
Fulltext Probable impact of age and hypoxia on proliferation and microRNA expression profile of bone marrow-derived human mesenchymal stem cells

Mohd Ali N, Boo L, Yeap SK, Ky H, Satharasinghe DA, Liew WC, et al.

PeerJ, 2016;4:e1536.
PMID: 26788424 DOI: 10.7717/peerj.1536

Decline in the therapeutic potential of bone marrow-derived mesenchymal stem cells (MSC) is often seen with older donors as compared to young. Although hypoxia is known as an approach to improve the therapeutic potential of MSC in term of cell proliferation and differentiation capacity, its effects on MSC from aged donors have not been well studied. To evaluate the influence of hypoxia on different age groups, MSC from young (<30 years) and aged (>60 years) donors were expanded under hypoxic (5% O2) and normal (20% O2) culture conditions. MSC from old donors exhibited a reduction in proliferation rate and differentiation potential together with the accumulation of senescence features compared to that of young donors. However, MSC cultured under hypoxic condition showed enhanced self-renewing and proliferation capacity in both age groups as compared to normal condition. Bioinformatic analysis of the gene ontology (GO) and KEGG pathway under hypoxic culture condition identified hypoxia-inducible miRNAs that were found to target transcriptional activity leading to enhanced cell proliferation, migration as well as decrease in growth arrest and apoptosis through the activation of multiple signaling pathways. Overall, differentially expressed miRNA provided additional information to describe the biological changes of young and aged MSCs expansion under hypoxic culture condition at the molecular level. Based on our findings, the therapeutic potential hierarchy of MSC according to donor's age group and culture conditions can be categorized in the following order: young (hypoxia) > young (normoxia) > old aged (hypoxia) > old aged (normoxia).
Phenotypic and microRNA characterisation of the neglected CD24+ cell population in MCF-7 breast cancer 3D spheroid culture

Boo L, Yeap SK, Ali NM, Ho WY, Ky H, Satharasinghe DA, et al.

J Chin Med Assoc, 2019 Nov 15.
PMID: 31770189 DOI: 10.1097/JCMA.0000000000000226

BACKGROUND: In vitro 3-dimensional spheroid culture has been widely used as model to enrich CD44CD24 cancer stem cells (CSC) with high ALDH1 activity. Although CD24subpopulation was known to be present in 3D spheroids and may influence cancer drug therapies, its characteristics and CSC properties were not well defined.
METHODS: In this study, CD24 population from the MCF-7 spheroid was sorted and subjected to spheroid formation test, stem cell markers immunofluorescence, invasion and migration test as well as microRNA expression profiling.
RESULTS: Sorted MCF-7 CD24 cells from primary spheroids were able to reform its 3D spheroid shape after 7 days in non-adherent culture conditions. In contrast to the primary spheroids, the expression of SOX-2, CD44, CD49f and Nanog were dim in MCF-7 CD24+ cells. Remarkably, MCF-7 CD24 cells were found to show high expression of ALDH1 protein which may have resulted in these cells exhibiting higher resistance against doxorubicin and cisplatin when compared to that of the parental cells. Moreover, microRNA profiling has shown that the absence of cancer stem cell properties were consistent with the downregulation of major cancer stem cells related pathways including Hedgehog, Wnt and MAPK signalling pathways. However, the upregulated pathways such as adherans junctions, focal adhesion and tight junction suggest that CD24+ cells were probably at an epithelial-like state of cell transition.
CONCLUSION: In conclusion, neglected CD24+ cells in MCF-7 spheroid did not exhibit typical breast CSCs properties. The presence of miRNAs and their analysed pathways suggested that these cells could be a distinct intermediate cell state in breast CSCs.
Fulltext Phenotypic and microRNA transcriptomic profiling of the MDA-MB-231 spheroid-enriched CSCs with comparison of MCF-7 microRNA profiling dataset

Boo L, Ho WY, Mohd Ali N, Yeap SK, Ky H, Chan KG, et al.

PeerJ, 2017;5:e3551.
PMID: 28717596 DOI: 10.7717/peerj.3551

Breast cancer spheroids have been widely used as in vitro models of cancer stem cells (CSCs), yet little is known about their phenotypic characteristics and microRNAs (miRNAs) expression profiles. The objectives of this research were to evaluate the phenotypic characteristics of MDA-MB-231 spheroid-enriched cells for their CSCs properties and also to determine their miRNAs expression profile. Similar to our previously published MCF-7 spheroid, MDA-MB-231 spheroid also showed typical CSCs characteristics namely self-renewability, expression of putative CSCs-related surface markers and enhancement of drug resistance. From the miRNA profile, miR-15b, miR-34a, miR-148a, miR-628 and miR-196b were shown to be involved in CSCs-associated signalling pathways in both models of spheroids, which highlights the involvement of these miRNAs in maintaining the CSCs features. In addition, unique clusters of miRNAs namely miR-205, miR-181a and miR-204 were found in basal-like spheroid whereas miR-125, miR-760, miR-30c and miR-136 were identified in luminal-like spheroid. Our results highlight the roles of miRNAs as well as novel perspectives of the relevant pathways underlying spheroid-enriched CSCs in breast cancer.
Fulltext MiRNA Transcriptome Profiling of Spheroid-Enriched Cells with Cancer Stem Cell Properties in Human Breast MCF-7 Cell Line

Boo L, Ho WY, Ali NM, Yeap SK, Ky H, Chan KG, et al.

Int J Biol Sci, 2016;12(4):427-45.
PMID: 27019627 DOI: 10.7150/ijbs.12777

Breast cancer is the second leading cause of cancer-related mortality worldwide as most patients often suffer cancer relapse. The reason is often attributed to the presence of cancer stem cells (CSCs). Recent studies revealed that dysregulation of microRNA (miRNA) are closely linked to breast cancer recurrence and metastasis. However, no specific study has comprehensively characterised the CSC characteristic and miRNA transcriptome in spheroid-enriched breast cells. This study described the generation of spheroid MCF-7 cell in serum-free condition and the comprehensive characterisation for their CSC properties. Subsequently, miRNA expression differences between the spheroid-enriched CSC cells and their parental cells were evaluated using next generation sequencing (NGS). Our results showed that the MCF-7 spheroid cells were enriched with CSCs properties, indicated by the ability to self-renew, increased expression of CSCs markers, and increased resistance to chemotherapeutic drugs. Additionally, spheroid-enriched CSCs possessed greater cell proliferation, migration, invasion, and wound healing ability. A total of 134 significantly (p<0.05) differentially expressed miRNAs were identified between spheroids and parental cells using miRNA-NGS. MiRNA-NGS analysis revealed 25 up-regulated and 109 down-regulated miRNAs which includes some miRNAs previously reported in the regulation of breast CSCs. A number of miRNAs (miR-4492, miR-4532, miR-381, miR-4508, miR-4448, miR-1296, and miR-365a) which have not been previously reported in breast cancer were found to show potential association with breast cancer chemoresistance and self-renewal capability. The gene ontology (GO) analysis showed that the predicted genes were enriched in the regulation of metabolic processes, gene expression, DNA binding, and hormone receptor binding. The corresponding pathway analyses inferred from the GO results were closely related to the function of signalling pathway, self-renewability, chemoresistance, tumorigenesis, cytoskeletal proteins, and metastasis in breast cancer. Based on these results, we proposed that certain miRNAs identified in this study could be used as new potential biomarkers for breast cancer stem cell diagnosis and targeted therapy.