Displaying all 19 publications

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  1. Cheah Y.K.
    Medicine & Health, 2014;9(1):62-73.
    MyJurnal
    The primary objective of the present study was to investigate the impact of sociodemographic factors on smoking and alcohol consumption among adults in Penang (Malaysia). A cross-sectional primary survey data with 398 respondents was used for analysis. The present study applied logistic regression models to examine the factors affecting the odds of smoking and alcohol consumption. The results showed that gender, ethnicity and education could significantly affect smoking. In particular, males (OR: 26.678) had a higher likelihood of smoking compared to the females, whereas Chinese (OR: 0.177), Indians/others (OR: 0.331) and individuals with tertiary education (OR: 0.258) had a lower likelihood of smoking than others. In terms of alcohol, gender, ethnicity and marital status were found to have a significant influence on the likelihood of alcohol consumption. Specifically, males (OR: 5.051), Chinese (OR: 37.796) and Indians/others (OR: 10.863) were more likely to consume alcohol than others, while married individuals (OR: 0.380) were less likely to consume alcohol than unmarried individuals. Based on the findings of the present study, numerous population-based intervention measures were suggested.
  2. Yeoh, T.K., Cheah, Y.K., Davies, R.
    MyJurnal
    Mid-exponential phase Saccharomyces rouxii YSa40 cells subsequently stressed at low aw/pH in the 0.64 aw/pH 3.5 glycerol/CPB system became injured. Such injury was detected by the loss of ability of the
    stressed population to form colonies on secondary-stress plating medium (glycerol/BM agar at 0.94 aw
    /pH 3.5 (lactic acid)) while colony forming ability on secondary non-stress plating medium (sugars/BM agar at 0.94 aw/pH 3.5 (lactic) was unaffected. The injury was shown to be due to sensitivity to glycerol/lactic acid. Results of the present study will be useful for achieving complete decontamination of ‘Intermediate Moisture Foods’ against xerotolerant molds and yeast.
  3. Jasbeer, K., Son, R., Mohamad Ghazali, F., Cheah, Y.K.
    MyJurnal
    Successful DNA amplification is vital for the detection of specific DNA targets in feeds, and this in return depends on the ability of DNA extraction methods to produce good quality DNA. In this study, seven methods were compared for DNA extraction from feeds using quantitative polymerase chain reaction (PCR) of single copy maize (Zea mays) endogenous hmg (high mobility group) gene. Relative levels of hmg were used to evaluate the DNA quality. Spectrophotometer determination of DNA was also carried out to assess DNA yield and DNA purity, while electrophoretic analysis of genomic DNA extracts was carried out to investigate DNA integrity. The findings illustrate that the DNA extraction methods have a significant effect on DNA quality. Statistically, the Epicentre method extracted the highest DNA yield while the Wizard method had the lowest DNA yield with high DNA purity and integrity. However, the Wizard method recovered the most amplifiable DNA per reaction, indicating that template quality and integrity had greater influence over hmg amplification than DNA yield.
  4. Jasbeer, K., Ghazali, F.M., Cheah, Y.K., Son, R.
    MyJurnal
    The introduction of new agricultural commodities and products derived from modernbiotechnology may have an impact on human and animal health, the environment and economiesof countries. As more Genetically Modified Organisms (GMO) enter markets worldwide, themonitoring of GMOs is being preferred for obvious reasons such as determination of seed purity,verification of non-GMO status of agricultural crops and fulfilling GMO labeling provisions, tomention a few. Numerous GMO analytical methods which include screening, identification andquantification have been developed to reliably determine the presence and/or amount of GMOin agricultural commodities, in raw agricultural materials and in processed and refined ingredients.The detection of GMOs relies on the detection of transgenic DNA or protein material. For routineanalysis, a good sample preparation technique should reproducibly generate DNA/protein ofsufficient quality, purity and yield while minimizing the effects of inhibition andcontamination.
    The key sample preparation steps include homogenization, pretreatment, extraction andpurification. Due to the fact that analytical laboratories receive samples that are often processedand refined, the quality and quantity of transgenic target analyte (e.g. protein and DNA) frequentlychallenge the sensitivity of any detection method. With the development of GMO analysistechniques, the Polymerase Chain Reaction (PCR) technique has been the mainstay for GMOdetection, and the real-time PCR is the most effective and important method for GMOquantification. The choice of target sequence; for example a promoter, a terminator, a gene, or ajunction between two of these elements, is the single most important factor controlling the specificity of the PCR method. Recent developments include event-specific methods, particularlyuseful for identification and quantification of GM content. Although PCR technology has obvious
    limitations, the potentially high degree of sensitivity and specificity explains why PCR in its various
    formats, is currently the leading analytical technology employed in GMO analysis. Comparatively, immunoassays are becoming attractive tools for rapid field monitoring for the integrity of agricultural commodities in identity preservation systems, whereby non-specialised personnel can employ them in cost-effective manner. This review discusses various popular extraction methodologies and summarises the current status of the most widely used and easily applicable GMO analysis technologies in laboratories, namely the PCR and immunoassay technologies.
  5. Fathinul Fikri,A.S, Nordin, A.J, Cheah, Y.K., Ahmad Saad, F.N.
    MyJurnal
    The escalating costs of conventional diagnostic technology in oncology have yet to obviate futile surgery intervention and the spiralling treatment cost. The evolution in engineering technology which looks at the correlation of the anatomy and the function of tumours i.e. Positron Emission Tomography-Computed Tomography (PET-CT) have impacted on the improved diagnostic accuracy and treatment in oncology. Clinical data have demonstrated that the information provided by PET/CT often changes patient management. This review addresses the value of PET-CT as a surrogate molecular marker in tumours and to discuss some issues in adopting PET/CT in routine daily practice as supported by the numbers of literature reviews of its application in oncology since it was first commercialised in 2001. The description of the technology used in multimodality imaging has gained encouraging interest among physicians, policy makers and insurance companies on the importance of the PET-CT, for which roles are not limited to the staging, disease prognostication and treatment monitoring with potential impact on treatment cost and justification of radiation safety for the patient. PET/CT is a useful tool in cancer investigation as evidenced by its role as a surrogate marker in underpinning the cellular reprogramming of different pathological entities.
  6. Cheah Y.K., Lee, L.H., Radu, S., Wong, M.C.V.L., Andrade, H.M.
    ASM Science Journal, 2009;3(2):113-120.
    MyJurnal
    The genus Streptomonospora is a group of extremely halophilic filamentous actinomycetes that form a distinct branch in the 16S rRNA gene phylogenetic tree adjacent to the genera Nocardiopsis and Thermobifida, family Norcadiopsaceae. To date, genus Streptomonospora only contain two validly described species which are Streptomonospora salina and Streptomonospora alba. During a biodiversity study on halophilic filamentous actinomycetes from 18 co-ordinates in Barrientos Island, Antarctic, numerous actinomycetes strains were isolated. To identify whether these isolates were members of the genus Streptomonospora, a genus specific primer that allow the rapid detection of the genus Streptomonospora by means of PCR amplification was used. Furthermore molecular cloning was performed to make identical and multiple copies of the target gene. In addition, morphological characteristic identification was performed to validate isolates with positive amplification during PCR.
  7. Cheah, Y.K., Azahadi, M., Phang, S.N., Abd Manaf, N.H.
    JUMMEC, 2019;22(1):33-40.
    MyJurnal
    Background: Depression is a serious mental health illness worldwide. The purpose of the study was to
    investigate the relationships between depression and its risk factors of sociodemography, lifestyle, and health
    among the adults of the different ethnic groups in Malaysia.

    Method: A nationwide database with 10141 observations was used. Multivariable logistic regression analyses
    stratified by ethnicity were estimated.

    Results: Ethnicity and gender, age, education, marital status and self-rated health were correlated to the
    likelihood of having depression. Malay females and smokers (AOR: 2.083) were more likely to suffer from
    depression than Malay males (AOR: 0.305) and non-smokers. Higher-income Chinese displayed higher odds of
    having depression than lower-income Chinese (AOR: 1.009). Indians and others with secondary-level education
    displayed a lower likelihood of developing depression compared to those with primary-level education (AOR:
    0.587).

    Conclusion: This study could contribute significantly to the formulation and development of an effective
    policy directed towards reducing the prevalence of depression in the vulnerable. These were the adults, in
    the younger age group, with lower education, with self-rated poor health, being female, unmarried, Malay
    and Chinese, and Indians and others. A nationwide policy targeted towards the Malay females to reduce
    their depression, with attention to the Chinese with a high income, and to the Indians and others with poor
    educational background to improve their knowledge of mental health, would be worthy of consideration.
  8. Wong, W.C., Pui, C.F., Tunung, R., Cheah, Y.K., Nakaguchi, Y., Nishibuchi, M., et al.
    MyJurnal
    A total of 112 burger patties (35 beef burger patties, 39 chicken burger patties and 38 fish burger patties) which are commercially available at retail level were investigated for the presence and number of Listeria monocytogenes. These samples were analyzed using MPN-PCR method and conventional culturing methods. L. monocytogenes was detected in 33.3% of chicken burger patties, 22.9% of beef patties, and 10.5% of fish patty samples. From all contaminated raw burger patties, the estimated count of L. monocytogenes was ranged from 3 to 75 MPN/g. The results suggest that burger act as a potential source of listeriosis if the contaminated burger patty is consumed without adequate cooking. The risk associated with consumption of these samples was found to be high particularly for processed food at retail level in Malaysia. Therefore, food manufacturers play an important role in monitoring the manufacturing process and conduct a periodical surveillance on microbiological quality assessment on the processing plants. Besides, there is a need to increase awareness of consumers and food handlers to practice proper cooking of the burger patties before the point of consumption, to reduce the risk of listeria infection.
  9. Wong, C.M.V.L., Chung, H.H., Aisyah, S., Omar, S., Cheah, Y.K., Maria de, L.G., et al.
    ASM Science Journal, 2009;3(2):107-112.
    MyJurnal
    There are relatively little data on bacteria with antimicrobial activities from Antarctic, especially from the South Shetland Islands when compared to the other parts of the world. Hence, this project was set to isolate and characterize bacteria that produce anti-microbial compounds from Greenwich Island (one of the South Shetland Islands), Antarctica. A total of 356 strains of bacteria were isolated from Greenwich Island. They were screened for antimicrobial activities against 13 Gram-negative and one Gram-positive indicator food-borne pathogens. Two out of the 356 Antarctic bacterial strains exhibited an antagonistic effect on the indicator strains, Escherichia coli, Salmonella spp., Klebsiella pneumoniae, Enterobacter cloacae, Vibrio parahaemolyticus and Bacillus cereus. The two Antarctic bacterial strains were designated as SS157 and SR13. Biochemical and 16S rDNA analysis indicated that the strain SS157 was closely related to Pseudomonas congelans while the strain SR13 was closely related to Pseudomonas tremae. The anti-microbial compounds produced by the two Antarctic bacteria were not sensitive to temperature and were not degraded by trypsin or pronase indicating that they were likely to be chemical compounds or antibiotics. Antimicrobial compounds from strains SS157 and SR13 were broad spectrum, and targeted both Gram-positive and negative pathogens.
  10. Usha, M.R., Fauziah, M., Tunung, R., Chai, L.C., Cheah, Y.K., Farinazleen, M.G., et al.
    MyJurnal
    Broiler part samples (80 fresh and 80 chilled) were examined for the prevalence and numbers of C. jejuni and C. coli by employing most-probable-number (MPN) and polymerase chain reaction (PCR) techniques. The prevalence of the bacteria was high where C. jejuni was detected in 92.5% fresh and 53.8% chilled samples while C. coli in 80.0% fresh and 56.3% chilled. The number of these bacteria in the positive fresh and chilled samples was from 3 to more than 2400 MPN/g and from 3 to 290 MPN/g, respectively. Antibiotic resistance test (using Kirby-Bauer disc diffusion method) on 10 C. jejuni and 13 C. coli isolates toward ampicillin, tobramycin, enrofloxacin, ciprofloxacin, tetracycline, cephalothin, gentamicin and norfloxacin revealed high resistance toward all antibiotics (20.0% - 100.0%). All isolates were resistant to at least two antibiotics. This study highlights the potential of multidrug-resistant C. jejuni and C. coli transmission to humans through fresh and chilled broiler parts. Consecutive studies with bigger sample sizes and covering all over Malaysia are warranted in future.
  11. Usha, M.R., Tunung, R., Chai, L.C., Ghazali, F.M., Cheah, Y.K., Nishibuchi, M., et al.
    MyJurnal
    Studies indicate that bacterial cross-contamination occurs during food preparation where bacteria can retent on the food contact surfaces and cause illness. The study evaluated the adherence of Campylobacter spp. to cutting boards, blades of knives and hands after cutting chilled, raw broiler parts (thighs + drumsticks, wings and livers). The adherence to cucumber cuts that were cut using the unwashed boards and knives was also analyzed. Generally, utensils have higher mean of Campylobacter spp. retained to them (1.4-223.3 MPN/ml rinse) than hands (0.7-43.4 MPN/ml rinse); however, Mann-Whitney U test showed no significant differences in the bacterial numbers found among the different surfaces. The transfer rates of Campylobacter spp. from utensils to cucumber cuts varied from 0% to more than 100%. The bacteria detected could be from the utensils and cucumber contamination before purchase or due to other factors where further investigation is required. The possibility is there for Campylobacter to spread to contact surfaces during chilled broiler handling; therefore, utensils and hands involved should be washed thoroughly especially before ready-to-eat food preparation.
  12. Ng, M.K., Abdulhadi-Noaman, Y., Cheah, Y.K., Yeap, S.K., Alitheen, N.B.
    MyJurnal
    Murraya paniculata (Linn) Jack (Orange Jasmine), known as "Kemuning Putih" in Malaysia, has been widely used as food flavor additive in cuisine by local residences. This is due to the strong fragrances of the leaves which make it suitable to be used in Indian and Malay dishes. Besides as a flavoring, leaves, branches, stem barks and roots of the plant are used in folk medicine to treat dysentery and morning sickness. Flowers of the plants are used in cosmetics. Since 1970’s, flavonoids and coumarins were isolated from Murraya paniculata, but no further bioactivity has been tested from the isolated compounds. The aim of this paper is to review and update the research related to chemical constituents and bioactivities of Murraya paniculata (L) Jack.
  13. Cheah, Y.K., Tay, L.W., Aida, A.A., Son, R., Nakaguchi, T., Nishibuchi, M.
    MyJurnal
    Escherichia coli and Escherichia coli O157 were identified from “selom” (Oenanthe stolonifera), “pegaga” (Centella asiatica), beef, chicken, lamb, buffalo, “ulam Raja” (Cosmos caudatus) and “tenggek burung” (Euodia redlevi). The bacteria were recovered using chromagenic agar. Isolated Escherichia coli and Escherichia coli 0157 were further characterized by plasmid profiling and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). The virulence genes of the isolates (VT1, VT2, LT, ST, eaeA, inV) that produces pathogenic Escherichia coli and 16S rRNA gene were screened by a multiplex PCR assay. The plasmid profiling analysis showed that out of 176 isolates, only 103 isolates contained plasmids. ERIC-PCR analysis generated amplified products in the range of ~150 bp to > 1000 bp categorizing isolates into a total of 52 different profiles. Multiplex PCR showed that 20 (32.3%) of the isolates carried eaeA gene, 6 (9.7%) isolates possessed inV genes, only 1 (1.6%) have VT2 genes and 1 (1.6%) as well carried VT1 genes, 2 (3.2%) of the isolates harboured LT genes, and only 1 (1.6%) isolate possessed ST genes. There were no correlation between plasmid, ERIC-PCR and virulence genes profiles.
  14. Jeyaletchumi, P, Tunung, R., Margaret, S.P, Son, R, Farinazleen, M.G., Cheah, Y.K
    MyJurnal
    Listeria monocytogenes is a gram positive, facultative intracellular pathogen with the capacity to cause
    food poisoning outbreaks as well as severe illness in vulnerable human population groups. It can cause a rare but serious disease called listeriosis with high fatality rates (20–30%) compared with other foodborne microbial pathogens. Although Listeria monocytogenes is infective to all human population groups, it is more likely to cause severe problems among pregnant women, immunocompromised individuals, the elderly and neonates. There are a variety of phenotyphic and genotyphic methods for the detection of Listeria monocytogenes in foods. Recent technological advances have increased the ability of scientists to detect Listeria monocytogenes. The purpose of this review is to discuss molecular characteristics of the Listeria monocytogenes pathogen, standard detection methods of this pathogen in foods based on culture methods, confirmation of species and subtyping based on phenotypic and genotyphic methods.
  15. Jeyaletchumi, P., Tunung, R., Margaret, S.P., Son, R., Ghazali, F.M., Cheah, Y.K., et al.
    MyJurnal
    The aim of this study was to assess the most probable number-polymerase chain reaction (MPNPCR) technique for detection of Listeria monocytogenes in salad vegetables in comparison with reference EN ISO 11290-2 and Food Drug Administration Bacteriological Analytical Manual method using artificial and naturally contaminated samples. Based on recovery of L. monocytogenes from artificially contaminated samples, MPN-PCR showed a moderate correlation (R=0.67) between spiking concentration and microbial levels which was better than the FDA-BAM method (R=0.642) and ISO 11290-2:1998 method (R=0.655). With naturally contaminated samples, it was found that L. monocytogenes was detected in 25% of the vegetable samples using MPN-PCR; 15% of the samples by the FDA-BAM method and 8% of samples using ISO 11290-2:1998 method. Overall, MPN-PCR was found to be a rapid and reliable method that could facilitate the enumeration of L. monocytogenes in vegetables.
  16. Ong, S.B., Zuraini, M.I., Jurin, W.G., Cheah Y.K., Tunung, R., Chai, L.C., et al.
    MyJurnal
    Three restriction enzymes were used in Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) using the mitochondrial cytochrome b region to establish a differential diagnosis which detect and discriminate between three meat species: pork, cow and chicken. DNA was extracted from samples containing meat of a single animal such as raw pork (Sus scrofa domesticus), chicken (Gallus gallus) and cow (Bos taurus) as well as mixed samples of two species of animals in different ratios. The amplified 359 base pairs (bp) portion of the mitochondrial cyt b gene from pure or mixed samples in different ratios was cut using three different restriction enzymes resulting in species specific restriction fragment length polymorphism (RFLP). This technique proved to be extremely reliable in detecting the presence of low levels of target DNA obtained from a 0.25 mg component in a particular mixed meat sample. This revealed the cyt b region as highly conserved and consequently a good molecular marker for diagnostic studies. Thus, this technique can be applied to food authentication for the identification of different species of animals in food products.
  17. Noor Hidayah, M.S., Tuan Zainazor, C., Pui, C.F., Noorlis, A., Noor Eliza, M.R., Naziehah, M.D., et al.
    MyJurnal
    Several Norovirus cases due to consumption of green onions have been reported during recent years but reports on red onions are not found. Onions are one of the major tastes in Malaysian food which are sometimes consuming raw especially the green onion. Viral contamination in onions can occur due to planting condition and not properly prepared food. This situation can pose the human health risk. A method was developed to detect the Norovirus that might present on different type of onions. In this study, 60 samples were collected from local market. Elution by Tryptose Phosphate Glycine broth and concentration steps using negatively charge filter were applied to enhance the detection of virus in food due to low copies of virus on food surface. The viral RNA was extracted using Qiagen Rneasy Mini kit before further detection using One-step RT-PCR. The total incidence of Norovirus in green onion and red onion was 13.33% (4/30) and 3.33 % (1/30) respectively. This is the first report of the detection of Norovirus in red and green onions in Malaysia. Based on the results, it is concluded that this method is reliable to detect Norovirus on onions and vegetables surface and hence can be applied in the laboratories for routine or food borne outbreak investigation.
  18. Tasrip, N.A., Khairil Mokhtar, N. F., Hanapi, U.K., Abdul Manaf, Y. N., Ali, M.E., Cheah, Y.K., et al.
    MyJurnal
    Isothermal amplification is a technique that can amplify target DNA sequences at a single incubation temperature. Loop-mediated isothermal amplification (LAMP) is an extension of the isothermal DNA amplification technique that combines rapidity, simplicity, high specificity and sensitivity. Due to its overwhelming characteristics, LAMP has been explored for its feasibility in detecting various subjects, and recently in meat-based food products for DNA-based meat species authentication. It has been developed to target various meat species such as porcine, chicken, horse, and ostrich with sensitivity as low as 0.1 pg/μL. Further improvement with the use of magnetic beads, electrochemiluminescence and special dye such as calcein and crystal violet had increased the sensitivity of the LAMP assay. Other important characteristics were specific target gene primers as well as a shorter incubation time, warranting a good prospect for rapid testing authentication.
  19. Noorlis, A., Ghazali, F.M., Cheah, Y.K., Tuan Zainazor, T.C., Ponniah, J., Tunung, R., et al.
    MyJurnal
    Little is known on the biosafety level of Vibrio spp. in freshwater fish in Malaysia. The purpose of this study was to investigate the prevalence and concentration of Vibrio spp. and V. parahaemolyticus in
    freshwater fish using the Most Probable Number-Polymerase Chain Reaction (MPN-PCR) method. The study was conducted on 150 samples from two types of freshwater fish commonly sold at hypermarkets, i.e. Pangasius hypophthalmus (catfish) and Oreochromis sp. (red tilapia). Sampling was done on the flesh, intestinal tract and gills of each fish. The prevalence of Vibrio spp. and V. parahaemolyticus was found to be 98.67% and 24% respectively with higher percentages detected in samples from the gills followed by the intestinal tract and flesh. Vibrio spp. was detected in almost all red tilapia and catfish samples. V. parahaemolyticus was detected in 25% of the catfish samples compared to 22.6% of red tilapia fish. The density of Vibrio spp. and V. parahaemolyticus in the samples ranged from 0 to 1.1x107 MPN/g. Although the maximum value was 1.1x107 MPN/g, most samples had microbial loads ranging from 0 to >104 MPN/g. The outcome on the biosafety assessment of Vibrio spp. and V. parahaemolyticus in freshwater fish indicates another potential source of food safety issues to consumers.
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