Displaying publications 1 - 20 of 92 in total

  1. Yusof, R., Abdul Rahman, P.S., Rahim, Z.H.A.
    Ann Dent, 1999;6(1):-.
    The application of PCR technique in genetic screening was demonstrated using the genetic materials from buccal cells of the students in the class. Two factors were taken into consideration when designing the experiments. The DNA region to be amplified should not be associated with any disease state. This is to eliminate any emotional and ethical problems associated with the experiments. In this practical, the presence and absence of a 38 bp sequence in the intron of COLIA2 gene were studied. The students were also shown on how to analyse the presence of homozygous and heterozygous alleles and the genetic variations that might be observed in the different ethnic groups of students. Another factor was the time taken to complete the experiment. Our experience showed that this experiment would take at least six hours to obtain and analyse the results. It is therefore suitable to be used in class teaching.
  2. Shabanzadeh P, Yusof R
    Comput Math Methods Med, 2015;2015:802754.
    PMID: 26336509 DOI: 10.1155/2015/802754
    Unsupervised data classification (or clustering) analysis is one of the most useful tools and a descriptive task in data mining that seeks to classify homogeneous groups of objects based on similarity and is used in many medical disciplines and various applications. In general, there is no single algorithm that is suitable for all types of data, conditions, and applications. Each algorithm has its own advantages, limitations, and deficiencies. Hence, research for novel and effective approaches for unsupervised data classification is still active. In this paper a heuristic algorithm, Biogeography-Based Optimization (BBO) algorithm, was adapted for data clustering problems by modifying the main operators of BBO algorithm, which is inspired from the natural biogeography distribution of different species. Similar to other population-based algorithms, BBO algorithm starts with an initial population of candidate solutions to an optimization problem and an objective function that is calculated for them. To evaluate the performance of the proposed algorithm assessment was carried on six medical and real life datasets and was compared with eight well known and recent unsupervised data classification algorithms. Numerical results demonstrate that the proposed evolutionary optimization algorithm is efficient for unsupervised data classification.
  3. Arfa R, Yusof R, Shabanzadeh P
    PeerJ Comput Sci, 2019;5:e206.
    PMID: 33816859 DOI: 10.7717/peerj-cs.206
    Trajectory clustering and path modelling are two core tasks in intelligent transport systems with a wide range of applications, from modeling drivers' behavior to traffic monitoring of road intersections. Traditional trajectory analysis considers them as separate tasks, where the system first clusters the trajectories into a known number of clusters and then the path taken in each cluster is modelled. However, such a hierarchy does not allow the knowledge of the path model to be used to improve the performance of trajectory clustering. Based on the distance dependent Chinese restaurant process (DDCRP), a trajectory analysis system that simultaneously performs trajectory clustering and path modelling was proposed. Unlike most traditional approaches where the number of clusters should be known, the proposed method decides the number of clusters automatically. The proposed algorithm was tested on two publicly available trajectory datasets, and the experimental results recorded better performance and considerable improvement in both datasets for the task of trajectory clustering compared to traditional approaches. The study proved that the proposed method is an appropriate candidate to be used for trajectory clustering and path modelling.
  4. Nor Rashid N, Yusof R, Rothan HA
    Trop Biomed, 2020 Sep 01;37(3):713-721.
    PMID: 33612784 DOI: 10.47665/tb.37.3.713
    Japanese encephalitis virus (JEV), a member of the family Flaviviridae, causes severe neurological disorders in humans. JEV infections represent one of the most widely spread mosquito-borne diseases, and therefore, it has been considered as an endemic disease. An effective antiviral drug is still unavailable to treat JEV, and current drugs only provide supportive treatment to alleviate the symptoms and stabilize patients' conditions. This study was designed to evaluate the antiviral activity of the sulphated polysaccharides "Carrageenan," a linear sulphated polysaccharide that is extracted from red edible seaweeds against JEV replication in vitro. Viral inactivation, attachment, and post-infection assays were used to determine the mode of inhibition of Carrageenan. Virus titters after each application were evaluated by plaque formation assay. MTT assay was used to determine the 50% cytotoxic concentration (CC50), and ELISA-like cell-based assay and immunostaining and immunostaining techniques were used to evaluate the 50% effective concentration (EC50). This study showed that Carrageenan inhibited JEV at an EC50 of 15 µg/mL in a dose-dependent manner with CC50 more than 200 µg/mL in healthy human liver cells (WRL68). The mode of inhibition assay showed that the antiviral effects of Carrageenan are mainly due to their ability to inhibit the early stages of virus infection such as the viral attachment and the cellular entry stages. Our investigation showed that Carrageenan could be considered as a potent antiviral agent to JEV infection. Further experimental and clinical studies are needed to investigate the potential applications of Carrageenan for clinical intervention against JEV infection.
  5. Yazdani S, Yusof R, Riazi A, Karimian A
    Diagn Pathol, 2014;9:207.
    PMID: 25540017 DOI: 10.1186/s13000-014-0207-7
    Brain segmentation in magnetic resonance images (MRI) is an important stage in clinical studies for different issues such as diagnosis, analysis, 3-D visualizations for treatment and surgical planning. MR Image segmentation remains a challenging problem in spite of different existing artifacts such as noise, bias field, partial volume effects and complexity of the images. Some of the automatic brain segmentation techniques are complex and some of them are not sufficiently accurate for certain applications. The goal of this paper is proposing an algorithm that is more accurate and less complex).
  6. Rashid NN, Yusof R, Watson RJ
    Anticancer Res, 2014 Nov;34(11):6557-63.
    PMID: 25368258
    It is well-established that HPV E7 proteins, encoded by human papillomavirus (HPV) genes, frequently associated with cervical cancers bind avidly to the retinoblastoma (RB) family of pocket proteins and disrupt their association with members of the E2F transcription factor family. Our previous study showed that the repressive p130-dimerization partner, RB-like, E2F and multi-vulval class (DREAM) complex was disrupted by HPV16 E7 proteins in order to maintain the viral replication in CaSki cells. However, we would like to address whether the activator B-myb-DREAM complex is critical in regulating the replication and mitosis phase since our previous study showed increased B-myb-DREAM expression in HPV-transformed cell lines when compared to control cells.
  7. Othman S, Rahman NA, Yusof R
    Trans R Soc Trop Med Hyg, 2010 Dec;104(12):806-8.
    PMID: 20800252 DOI: 10.1016/j.trstmh.2010.07.004
    In contrast to many viruses that escape the host's immune responses by suppressing the major histocompatibility complex (MHC) class I pathway, flaviviruses have been shown to up-regulate the cell surface expression of MHC class I complex. The mechanism by which dengue virus (DV) achieves this up-regulation remains unclear. Our investigation on the HLA-A2 gene in human liver cells demonstrated that all four serotypes of dengue virus, DV1 to DV4, resulted in variable degrees of promoter induction. This illustrates the importance of MHC class I transcription regulation in primary infections by different DV serotypes that may have even greater impact in secondary infections, associated with increased disease severity.
  8. Gan CS, Yusof R, Othman S
    Acta Trop, 2015 Sep;149:8-14.
    PMID: 25981524 DOI: 10.1016/j.actatropica.2015.05.005
    Dengue virus (DV) infection demonstrates an intriguing virus-induced intracellular membrane alteration that results in the augmentation of major histocompatibility complex (MHC) class I-restricted antigen presentation. As oppose to its biological function in attracting CD8(+) T-cells, this phenomenon appears to facilitate the immune evasion. However, the molecular events that attribute to the dysregulation of the antigen presenting mechanism (APM) by DV remain obscure. In this study, we aimed to characterize the host cell APM upon infection with all serotypes of whole DV. Cellular RNA were isolated from infected cells and the gene expressions of LMP2, LMP7, TAP1, TAP2, TAPBP, CALR, CANX, PDIA3, HLA-A and HLA-B were analyzed via quantitative PCR. The profiles of the gene expression were further validated. We showed that all four DV serotypes modulate host APM at the proteasomal level with DV2 showing the most prominent expression profile.
  9. Yazdani S, Yusof R, Karimian A, Riazi AH, Bennamoun M
    Comput Math Methods Med, 2015;2015:829893.
    PMID: 26089978 DOI: 10.1155/2015/829893
    Brain MRI segmentation is an important issue for discovering the brain structure and diagnosis of subtle anatomical changes in different brain diseases. However, due to several artifacts brain tissue segmentation remains a challenging task. The aim of this paper is to improve the automatic segmentation of brain into gray matter, white matter, and cerebrospinal fluid in magnetic resonance images (MRI). We proposed an automatic hybrid image segmentation method that integrates the modified statistical expectation-maximization (EM) method and the spatial information combined with support vector machine (SVM). The combined method has more accurate results than what can be achieved with its individual techniques that is demonstrated through experiments on both real data and simulated images. Experiments are carried out on both synthetic and real MRI. The results of proposed technique are evaluated against manual segmentation results and other methods based on real T1-weighted scans from Internet Brain Segmentation Repository (IBSR) and simulated images from BrainWeb. The Kappa index is calculated to assess the performance of the proposed framework relative to the ground truth and expert segmentations. The results demonstrate that the proposed combined method has satisfactory results on both simulated MRI and real brain datasets.
  10. Yusof RM, Haque F, Ismail M, Hassan Z
    Asia Pac J Clin Nutr, 2000 Jun;9(2):130-5.
    PMID: 24394399
    Probiotic organism Bifidobacteria was isolated from the faeces of breast-fed infants at Universiti Putra Malaysia. Trypticase phytone peptone yeast extract agar (TPY) was used as a selective media for the isolation. Morphological examination of the isolates indicated that Bifidobacteria was Gram-positive rods in nature, curved with characteristics of V and Y shapes. The organisms were non-catalase producing, non-nitrate reducing, non-motile, had an absence of indole and were unable to liquify gelatin. The ratios of acetic and lactic acids were determined using high performance liquid chromatography (HPLC). Using carbohydrate fermentation profile test API-CH-50 kits, 20 Bifidobacteria strains had been identified: they were the species of Bifidobacteria infantis and two different sub-species, mainly infantis and lacentis. Based on a wide zone of inhibition, three suitable strains of B. infantis, Bifi-11, Bifi-19 and Bifi-20, were tested in weaning foods for antimicrobial activity towards two human pathogens: E. coli-0157 (World Health Organization) and Salmonella typhimurium S-285. The pH, titratable acidity of weaning foods and total colony count for Bifidobacteria, enteropathogenic Escherichia coli and S. typhimurium were recorded at 3-h intervals for 30 h. It was found that after 9 h of incubation of weaning foods, the pH declined to < 3.6 from pH 6.0, whereas titratable acidity increased from 0.026 to 0.08%. It was indicated that Bifidobacteria inhibited E. coli better than did S typhimurium due to low pH. After 24 h of incubation, approximately 98% of E. coli was inhibited by Bifidobacteria. It is suggested that the inhibitory effect of Bifidobacteria strains in weaning foods towards the growth of enteropathogenic E. coli and S. typhimurium was solely due to low pH and the production of volatile acid components by the organism.
  11. Othman S, Rahman NA, Yusof R
    Virus Res, 2012 Jan;163(1):238-45.
    PMID: 22001567 DOI: 10.1016/j.virusres.2011.09.040
    Despite aggressive efforts in dengue research, the control of dengue diseases and discovery of therapeutics against them await complete elucidation of its complex immune-pathogenesis. Unlike many viruses that escape the host's immune responses by suppressing the major histocompatibility complex (MHC) Class I pathway, many Flaviviruses up-regulate the cell surface expression of MHC Class I complex. We recently reported MHC Class I HLA-A2 promoter activation by all serotypes of dengue virus (DV). The mechanism by which DV regulates this is further explored here in HepG2 human liver cell line. Using real-time PCR, evidence that, similar to infections by other Flaviviruses, DV infection has the ability to up-regulate the MHC Class I transcription and mRNA synthesis, is presented. The region responsive towards DV infection of all serotypes was mapped to the Class I Regulatory Complex (CRC) of the HLA-A2 promoter. Competition electrophoretic mobility shift assay (EMSA) with NFκB probe established the presence of specific DNA-protein complex in DV-infected nuclear extracts. Antibody-supershift assays identified the MHC Class I promoter activation by DV to occur through binding of p65/p50 heterodimers and p65 homodimers to κB1 and κB2 cis-acting elements, respectively, within the CRC, and not with the interferon consensus sequence (ICS). This study presents evidence of MHC Class I gene modulation by DV, hence providing a better understanding of dengue immune-pathogenesis that would consequently facilitate the discovery of antiviral therapeutics against dengue.
  12. Shafie MH, Yusof R, Gan CY
    Carbohydr Polym, 2019 Jul 15;216:303-311.
    PMID: 31047070 DOI: 10.1016/j.carbpol.2019.04.007
    The Box-Behnken design was applied to optimize the extraction of pectin from Averrhoa bilimbi (ABP) using deep eutectic solvents (DES). The four variables of extraction were percentage of DES (X1), extraction time (X2), temperature (X3), and molar ratio of DES components (X4). The quadratic regression equation was established as a predicted model with R2 value of 0.9375. The optimal condition was X1 = 3.74% (w/v), X2 = 2.5 h, X3 = 80 °C, and X4 = 1:1. No significant difference between the predicted (14.70%) and experimental (14.44%) maximum yield of sample was noted. Characterization of physico-chemical properties characterization of ABP was performed. The main components of ABP were galacturonic acids, arabinoses, and xyloses. ABP also showed good functional properties such as water holding capacity (3.70 g/g), oil holding capacity (2.40 g/g), and foaming capacity (133.33%). The results also showed that ABP exhibited free radical scavenging activity (41.46%) and ferric reducing antioxidant power (1.15 mM).
  13. Nor Rashid N, Yusof R, Watson RJ
    J Gen Virol, 2011 Nov;92(Pt 11):2620-2627.
    PMID: 21813705 DOI: 10.1099/vir.0.035352-0
    Human papillomaviruses (HPVs) with tropism for mucosal epithelia are the major aetiological factors in cervical cancer. Most cancers are associated with so-called high-risk HPV types, in particular HPV16, and constitutive expression of the HPV16 E6 and E7 oncoproteins is critical for malignant transformation in infected keratinocytes. E6 and E7 bind to and inactivate the cellular tumour suppressors p53 and Rb, respectively, thus delaying differentiation and inducing proliferation in suprabasal keratinocytes to enable HPV replication. One member of the Rb family, p130, appears to be a particularly important target for E7 in promoting S-phase entry. Recent evidence indicates that p130 regulates cell-cycle progression as part of a large protein complex termed DREAM. The composition of DREAM is cell cycle-regulated, associating with E2F4 and p130 in G0/G1 and with the B-myb transcription factor in S/G2. In this study, we addressed whether p130-DREAM is disrupted in HPV16-transformed cervical cancer cells and whether this is a critical function for E6/E7. We found that p130-DREAM was greatly diminished in HPV16-transformed cervical carcinoma cells (CaSki and SiHa) compared with control cell lines; however, when E6/E7 expression was targeted by specific small hairpin RNAs, p130-DREAM was reformed and the cell cycle was arrested. We further demonstrated that the profound G1 arrest in E7-depleted CaSki cells was dependent on p130-DREAM reformation by also targeting the expression of the DREAM component Lin-54 and p130. The results show that continued HPV16 E6/E7 expression is necessary in cervical cancer cells to prevent cell-cycle arrest by a repressive p130-DREAM complex.
  14. Norhayati MN, Che Yusof R, Azman MY
    PLoS One, 2021;16(6):e0252603.
    PMID: 34086747 DOI: 10.1371/journal.pone.0252603
    BACKGROUND: In the fight against the COVID-19 pandemic, frontline healthcare providers who are engaged in the direct diagnosis, treatment, and care of patients face a high risk of infection yet receive inadequate protection from contamination and minimal support to cope with overwork, frustration, and exhaustion. These problems have created significant psychological and mental health concerns for frontline healthcare providers. This study aimed to compare the levels of vicarious traumatization between frontline and non-frontline healthcare providers in response to the COVID-19 pandemic.

    METHODOLOGY: All the subjects who met the inclusion criteria were recruited for this comparative cross-sectional study, which was conducted from May to July 2020 in two hospitals in Kelantan, Malaysia. A self-administered questionnaire, namely, the Malay-version Vicarious Traumatization Questionnaire and the Medical Outcome Study Social Support Survey were utilized. A descriptive analysis, independent t-test, and analysis of covariance were performed using SPSS Statistics version 26.

    RESULTS: A total of 160 frontline and 146 non-frontline healthcare providers were recruited. Vicarious traumatization was significantly higher among the non-frontline healthcare providers (estimated marginal mean [95% CI]: 79.7 [75.12, 84.30]) compared to the frontline healthcare providers (estimated marginal mean [95% CI]: 74.3 [68.26, 80.37]) after adjusting for sex, duration of employment, and social support.

    CONCLUSION: The level of vicarious traumatization was higher among non-frontline compared to frontline healthcare providers. However, the level of severity may differ from person to person, depending on how they handle their physical, psychological, and mental health. Hence, support from various resources, such as colleagues, family, the general public, and the government, may play an essential role in the mental health of healthcare providers.

  15. Norhayati MN, Che Yusof R, Azman MY
    PLoS One, 2021;16(8):e0256932.
    PMID: 34464399 DOI: 10.1371/journal.pone.0256932
    BACKGROUND: Healthcare providers are vulnerable in the fight against COVID-19 and may experience significant psychological and mental health consequences. This study aimed to compare the levels of depressive symptoms among frontline and non-frontline healthcare providers in response to the COVID-19 pandemic.

    METHODS: A comparative cross-sectional study was conducted in two government hospitals managing COVID-19-related cases in Kelantan, Malaysia from May to July 2020 to identify and compared depressive symptoms levels of frontline and non-frontline healthcare providers. Convenient sampling was applied in the selection of eligible participants and those diagnosed as having any psychiatric illnesses were excluded. The self-administered questionnaires for the Malay versions of the Hospital Anxiety and Depression Scale to measure depressive symptoms score and the Medical Outcome Study Social Support Survey to measure social support score as an important confounder. A descriptive analysis, independent t-test and ANCOVA were performed using SPSS version 26.

    RESULTS: A total of 306 respondents from healthcare providers were recruited which 160 were frontline healthcare providers and 146 were non-frontline healthcare providers. The level of depressive symptoms (HADS score >8) was 27.5% for the frontline healthcare providers and 37.7% for the non-frontline healthcare providers. The mean depressive symptoms score for the non-frontline healthcare providers was 0.75 points higher than that of the frontline healthcare providers after adjusting for gender, duration of employment and social support.

    CONCLUSION: Non-frontline healthcare providers are also experiencing psychological distress during the COVID-19 pandemic even though they do not have direct contact with COVID-19 patients.

  16. Norhayati MN, Che Yusof R, Azman MY
    PMID: 34501747 DOI: 10.3390/ijerph18179157
    COVID-19 has impacted people psychologically globally, including healthcare providers. Anxiety, depression, and stress are the most common impacts that have affected these people. Thus, this study was aimed to ascertain the estimated prevalence of psychological impacts among healthcare providers in the Asian region. A systematic search was performed in the MEDLINE, CINAHL, and Scopus databases for original research articles published between 2020 and April 2021. Only studies published in English were included. The quality of data was assessed using the Joanna Briggs Institute Meta-Analysis, and the analysis was performed using generic inverse variance with a random-effects model by Review Manager software. A total of 80 studies across 18 countries in Asia region were pooled to assess the data prevalence on anxiety (34.81% (95% CI: 30.80%, 38.83%)), depression (34.61% (95% CI: 30.87%, 38.36%)), stress (31.72% (95% CI: 21.25%, 42.18%)), insomnia (37.89% (95% CI: 25.43%, 50.35%)), and post-traumatic stress disorder (15.29% (95% CI: 11.43%, 19.15%)). Subgroup analyses were conducted across regions, type of healthcare providers, sex, and occupation. This review has identified a high prevalence of anxiety, depression, stress, and insomnia but a low prevalence of post-traumatic stress disorder among healthcare providers in Asia regions. Effective intervention support programs are urgently needed to improve psychological health of healthcare providers and maintaining the health system.
  17. Nor Rashid N, Yong ZL, Yusof R, Watson RJ
    Virol J, 2016 Jan 04;13:2.
    PMID: 26728921 DOI: 10.1186/s12985-015-0460-8
    Retinoblastoma like protein 2 (RBL2) or p130 is a member of the pocket protein family, which is infrequently mutated in human tumours. Its expression is posttranscriptionally regulated and largely G0 restricted. We have previously shown that E6/E7 oncoproteins encoded by human papillomavirus (HPV) type 16, which is a high-risk type for cervical cancer development, must target p130 to promote the host cell to exit from quiescence (G0) state and enter S phase of the cell cycle. P130 is associated with the DREAM (DP, RB-like, E2F and MuvB) complex in G0/G1, which prevents S phase progression by repressing transcription of E2F-regulated genes. E7 proteins could potentially disrupt the p130-DREAM complex through two known mechanisms: direct interaction with p130 or induction of cyclin dependent kinase 2 (CDK2) phosphorylation by interacting with its inhibitor, p21(CIP1).
  18. Yusof R, Abdulmalek E, Sirat K, Rahman MB
    Molecules, 2014 Jun 13;19(6):8011-26.
    PMID: 24932572 DOI: 10.3390/molecules19068011
    Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES.
  19. Rothan HA, Bahrani H, Mohamed Z, Abd Rahman N, Yusof R
    PLoS One, 2014;9(4):e94561.
    PMID: 24722532 DOI: 10.1371/journal.pone.0094561
    Dengue virus (DENV) broadly disseminates in tropical and sub-tropical countries and there are no vaccine or anti-dengue drugs available. DENV outbreaks cause serious economic burden due to infection complications that requires special medical care and hospitalization. This study presents a new strategy for inexpensive production of anti-DENV peptide-fusion protein to prevent and/or treat DENV infection. Antiviral cationic peptides protegrin-1 (PG1) and plectasin (PLSN) were fused with MAP30 protein to produce recombinant antiviral peptide-fusion protein (PG1-MAP30-PLSN) as inclusion bodies in E. coli. High yield production of PG1-MAP30-PLSN protein was achieved by solubilization of inclusion bodies in alkaline buffer followed by the application of appropriate refolding techniques. Antiviral PG1-MAP30-PLSN protein considerably inhibited DENV protease (NS2B-NS3pro) with half-maximal inhibitory concentration (IC50) 0.5±0.1 μM. The real-time proliferation assay (RTCA) and the end-point proliferation assay (MTT assay) showed that the maximal-nontoxic dose of the peptide-fusion protein against Vero cells is approximately 0.67±0.2 μM. The cell-based assays showed considerable inhibition of the peptide-fusion protein against binding and proliferating stages of DENV2 into the target cells. The peptide-fusion protein protected DENV2-challeged mice with 100% of survival at the dose of 50 mg/kg. In conclusion, producing recombinant antiviral peptide-fusion protein by combining short antiviral peptide with a central protein owning similar activity could be useful to minimize the overall cost of short peptide production and take advantage of its synergistic antiviral activities.
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