Displaying publications 1 - 20 of 39 in total

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  1. Hao Y, Tai VC, Tan YC
    Sensors (Basel), 2023 Oct 03;23(19).
    PMID: 37837069 DOI: 10.3390/s23198240
    This research aimed to optimize the camera calibration process by identifying the optimal distance and angle for capturing checkered board images, with a specific focus on understanding the factors that influence the reprojection error (ϵRP). The objective was to improve calibration efficiency by exploring the impacts of distance and orientation factors and the feasibility of independently manipulating these factors. The study employed Zhang's camera calibration method, along with the 2k full-factorial analysis method and the Latin Hypercube Sampling (LHS) method, to identify the optimal calibration parameters. Three calibration methods were devised: calibration with distance factors (D, H, V), orientation factors (R, P, Y), and the combined two influential factors from both sets of factors. The calibration study was carried out with three different stereo cameras. The results indicate that D is the most influential factor, while H and V are nearly equally influential for method A; P and R are the two most influential orientation factors for method B. Compared to Zhang's method alone, on average, methods A, B, and C reduce ϵRP by 25%, 24%, and 34%, respectively. However, method C requires about 10% more calibration images than methods A and B combined. For applications where lower value of ϵRP is required, method C is recommended. This study provides valuable insights into the factors affecting ϵRP in calibration processes. The proposed methods can be used to improve the calibration accuracy for stereo cameras for the applications in object detection and ranging. The findings expand our understanding of camera calibration, particularly the influence of distance and orientation factors, making significant contributions to camera calibration procedures.
  2. Chan KH, Mohammed Haspani MS, Tan YC, Kassim F
    Malays J Med Sci, 2011 Jul;18(3):82-6.
    PMID: 22135607 MyJurnal
    Primary central nervous system atypical rhabdoid/teratoid tumour (ATRT) is a rare and highly malignant tumour that tends to occur in infancy and early childhood. The majority of tumours (approximately two-third) arise in the posterior fossa. The optimal treatment for ATRT remains unclear. Options of treatment include surgery, radiotherapy, and chemotherapy. Each of their role is still not clearly defined until now. The prognosis of the disease is generally unfavourable. This is a case report of ATRT in an atypical site in a 9-year-old girl.
  3. Abdullah MZ, Awang MS, Tan YC, Abdullah JM
    J Neurol Surg A Cent Eur Neurosurg, 2014 Mar;75(2):155-7.
    PMID: 23636911 DOI: 10.1055/s-0032-1330954
    The study assesses the capability and accuracy of a robotic arm to perform burr holes.
  4. Asghar A, Tan YC, Zahoor M, Zainal Abidin SA, Yow YY, Khan E, et al.
    Sci Rep, 2021 Jul 05;11(1):13859.
    PMID: 34226594 DOI: 10.1038/s41598-021-92622-0
    The emergence and spread of antimicrobial resistance have been of serious concern to human health and the management of bacterial infectious diseases. Effective treatment of these diseases requires the development of novel therapeutics, preferably free of side effects. In this regard, natural products are frequently conceived to be potential alternative sources for novel antibacterial compounds. Herein, we have evaluated the antibacterial activity of the epicarp extracts of the Malaysian cultivar of yellow rambutan fruit (Nephelium lappaceum L.) against six pathogens namely, Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella enterica. Among a series of solvent extracts, fractions of ethyl acetate and acetone have revealed significant activity towards all tested strains. Chemical profiling of these fractions, via HPLC, LC-MS and GC-MS, has generated a library of potentially bioactive compounds. Downstream virtual screening, pharmacological prediction, and receptor-ligand molecular dynamics simulation have eventually unveiled novel potential antibacterial compounds, which can be extracted for medicinal use. We report compounds like catechin, eplerenone and oritin-4-beta-ol to be computationally inhibiting the ATP-binding domain of the chaperone, DnaK of P. aeruginosa and MRSA. Thus, our work follows the objective to propose new antimicrobials capable of perforating the barrier of resistance posed by both the gram positives and the negatives.
  5. Ibraheem ZO, Satar M, Abdullah NA, Rathore H, Tan YC, Uldin F, et al.
    Pak J Pharm Sci, 2014 Jan;27(1):1-9.
    PMID: 24374430
    Recently, it is suggested to use POLE (palm oil leaf extract) as a nutraceutical health product in food industry due to its newly discovered content of polyphenols and antioxidant vitamins. In the experiment, the antioxidant and anti-lipid-peroxidation activities of the extract were confirmed using; DPPH (1-diphenyl-2-picryl-hydrazil) radical scavenging activity, ferric ion induced lipid peroxidation inhibition, reducing power and hydrogen peroxide scavenging activity assays. The cardio-protective activity was studied in vivo using a model of metabolic syndrome induced by high fat diet. Lipid profile, obesity indices, renal tubular handling of water and electrolytes, blood pressure and arterial stiffness were measured at the end of the treatment period. Sprague Dawley rats weighing 150-200 g were divided into six groups, viz; group C; was treated as a negative control and fed with standard rodents chow, group H; was treated as a positive control and fed with an experimental diet enriched with saturated free fatty acids for 8 weeks, groups HP0.5, HP1 and HP2 which were fed with 0.5,1 and 2 g/kg (body weight) /day of POLE orally during the last 24 days of the high fat diet feeding period and group P; fed with highest dose of POLE. Results revealed that POLE possesses a cardio-protective effect which is ascribed to its content of polyphenols.
  6. Tan YC, Abdul Sattar M, Ahmeda AF, Abdul Karim Khan N, Murugaiyah V, Ahmad A, et al.
    PLoS One, 2020;15(4):e0231472.
    PMID: 32298299 DOI: 10.1371/journal.pone.0231472
    Oxidative stress is involved in the pathogenesis of a number of diseases including hypertension and renal failure. There is enhanced expression of nicotinamide adenine dinucleotide (NADPH oxidase) and therefore production of hydrogen peroxide (H2O2) during renal disease progression. This study investigated the effect of apocynin, an NADPH oxidase inhibitor and catalase, an H2O2 scavenger on Cyclosporine A (CsA) nephrotoxicity in Wistar-Kyoto rats. Rats received CsA (25mg/kg/day via gavage) and were assigned to vehicle, apocynin (2.5mmol/L p.o.), catalase (10,000U/kg/day i.p.) or apocynin plus catalase for 14 days. Renal functional and hemodynamic parameters were measured every week, and kidneys were harvested at the end of the study for histological and NADPH oxidase 4 (NOX4) assessment. Oxidative stress markers and blood urea nitrogen (BUN) were measured. CsA rats had higher plasma malondialdehyde (by 340%) and BUN (by 125%), but lower superoxide dismutase and total antioxidant capacity (by 40%, all P<0.05) compared to control. CsA increased blood pressure (by 46mmHg) and decreased creatinine clearance (by 49%, all P<0.05). Treatment of CsA rats with apocynin, catalase, and their combination decreased blood pressure to near control values (all P<0.05). NOX4 mRNA activity was higher in the renal tissue of CsA rats by approximately 63% (P<0.05) compared to controls but was reduced in apocynin (by 64%), catalase (by 33%) and combined treatment with apocynin and catalase (by 84%) compared to untreated CsA rats. Treatment of CsA rats with apocynin, catalase, and their combination prevented hypertension and restored renal functional parameters and tissue Nox4 expression in this model. NADPH inhibition and H2O2 scavenging is an important therapeutic strategy during CsA nephrotoxicity and hypertension.
  7. Sim SK, Ch'ng CH, Tan YC, Kandasamy R, Abdullah JM
    Med J Malaysia, 2014 Apr;69(2):86-8.
    PMID: 25241818 MyJurnal
    Subtentorial subdural empyema is a rare and life threatening intracranial suppuration. It is usually an intracranial complication of otogenic infections. Early diagnosis and surgical drainage are the most important factors determining prognosis. The high mortality reported in the literature reflects the severity of subtentorial subdural empyema if proper management is delayed. Intracranial infections usually require between 4 to 6 weeks of intravenous antibiotics therapy. However, the prolonged duration of hospitalization as well as requirement for neurosurgically inserted indwelling devices may predispose these patients to new nosocomial infections.
  8. Badrisyah I, Saiful R, Rahmat H, Naik VR, Tan YC
    Med J Malaysia, 2012 Dec;67(6):613-5.
    PMID: 23770956 MyJurnal
    Metastasis of an atrial myxoma to the brain is extremely rare. Thus far there are only 17 cases reported, including our present case. Most of the brain metastases manifest only in 3 to 6 decades, after an average time frame of one to two years after surgical removal of parental tumour. We present a case of brain metastases of atrial myxoma in a teenager of the youngest age among all reported cases, unusually as early as 15 years old. The progress of the metastatic process had been insidious for three years after heart surgery, The imaging demonstrated a rather sizeable tumour by the time when the patient is symptomatic. The location of the metastatic tumour is anyhow superficial to the cortical surface, enabling complete surgical excision of the tumour easily achievable with favourable outcome.
  9. Wong YC, Abd El Ghany M, Naeem R, Lee KW, Tan YC, Pain A, et al.
    Front Microbiol, 2016;7:1288.
    PMID: 27597847 DOI: 10.3389/fmicb.2016.01288
    Burkholderia cenocepacia infection often leads to fatal cepacia syndrome in cystic fibrosis patients. However, antibiotic therapy rarely results in complete eradication of the pathogen due to its intrinsic resistance to many clinically available antibiotics. Recent attention has turned to the identification of essential genes as the proteins encoded by these genes may serve as potential targets for development of novel antimicrobials. In this study, we utilized TraDIS (Transposon Directed Insertion-site Sequencing) as a genome-wide screening tool to facilitate the identification of B. cenocepacia genes essential for its growth and viability. A transposon mutant pool consisting of approximately 500,000 mutants was successfully constructed, with more than 400,000 unique transposon insertion sites identified by computational analysis of TraDIS datasets. The saturated library allowed for the identification of 383 genes that were predicted to be essential in B. cenocepacia. We extended the application of TraDIS to identify conditionally essential genes required for in vitro growth and revealed an additional repertoire of 439 genes to be crucial for B. cenocepacia growth under nutrient-depleted conditions. The library of B. cenocepacia mutants can subsequently be subjected to various biologically related conditions to facilitate the discovery of genes involved in niche adaptation as well as pathogenicity and virulence.
  10. Sim SK, Tan YC, Ghani ARI
    Med J Malaysia, 2020 01;75(1):38-42.
    PMID: 32008018
    INTRODUCTION: Cerebral venous sinus thrombosis (CVST) is a potentially fatal neurological condition. However, due to the non-specific clinical and radiological features of CVST, it can sometimes result in a delay in the diagnosis and subsequent management. The aim of this study was to evaluate the demography, risk factors and one-year outcome of CVST patients treated in Hospital Universiti Sains Malaysia.

    METHODS: In this retrospective study, we reviewed the cases diagnosed with CVST admitted to our centre from January 2011 until November 2015.

    RESULTS: A total of 15 patients were included in this review. The patterns of imaging findings as well as risk factors for CVST is discussed with a review of the literature and current management practices. One year followed-up showed full recovery (Glasgow Outcome Scale (GOS) of 5) in 10 cases (66.7%), whereas 4 cases (26.7%) with GOS of 4 (three cases with neurological deficits, and 1 case with mild symptom. There was one case of mortality in this study secondary to sepsis during hospitalisation. The presenting symptoms were mainly headache, focal neurology deficits, seizure and altered sensorium. Risk factors identified were oral contraceptive pills usage, chronic sinuses or ear infections, and obesity. Initial computed tomography (CT) scan showed various findings and haemorrhagic infarct was one of the common findings. Magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) revealed majority of the patients had occlusion at two or more venous sinus sites. No patients had new or recurrent intracranial haemorrhage following initiation of anticoagulation therapy.

    CONCLUSION: Thus it is considerable safe to start anticoagulation therapy in CVST patients including those with intracranial haemorrhage. We propose further neuroimaging to avoid missed diagnosis of CVST in patient presented with recent onset headache and CT evidence of unusual cerebral infarction.

  11. Cheong WH, Tan YC, Yap SJ, Ng KP
    Bioinformatics, 2015 Nov 15;31(22):3685-7.
    PMID: 26227146 DOI: 10.1093/bioinformatics/btv433
    : We present ClicO Free Service, an online web-service based on Circos, which provides a user-friendly, interactive web-based interface with configurable features to generate Circos circular plots.
  12. Kuan CS, Ng KP, Yew SM, Umar Meleh H, Seow HF, How KN, et al.
    Braz J Microbiol, 2023 Sep;54(3):1351-1372.
    PMID: 37351789 DOI: 10.1007/s42770-023-01032-z
    Neoscytalidium dimidiatum and Bipolaris species are fungal plant pathogens that have been reported to cause human diseases. Recently, we have isolated numerous N. dimidiatum and Bipolaris species from the skin scrapings and nails of different patients. In this work, we have sequenced the genome of one strain of N. dimidiatum. The sequenced genome was compared to that of a previously reported Bipolaris papendorfii genome for a better understanding of their complex lifestyle and broad host-range pathogenicity. Both N. dimidiatum UM 880 (~ 43 Mb) and B. papendorfii UM 226 (~ 33 Mb) genomes include 11,015-12,320 putative coding DNA sequences, of which 0.51-2.49% are predicted transposable elements. Analysis of secondary metabolism gene clusters revealed several genes involved in melanin biosynthesis and iron uptake. The arsenal of CAZymes related to plants pathogenicity is comparable between the species, including genes involved in hemicellulose and pectin decomposition. Several important gene encoding keratinolytic peptidases were identified in N. dimidiatum and B. papendorfii, reflecting their potential pathogenic role in causing skin and nail infections. In this study, additional information on the metabolic features of these two species, such as nutritional profiling, pH tolerance, and osmotolerant, are revealed. The genomic characterization of N. dimidiatum and B. papendorfii provides the basis for the future functional studies to gain further insights as to what makes these fungi persist in plants and why they are pathogenic to humans.
  13. Jabeen S, Yap HY, Abdullah FFJ, Zakaria Z, Isa NM, Tan YC, et al.
    Genes (Basel), 2019 01 25;10(2).
    PMID: 30691021 DOI: 10.3390/genes10020081
    Although more than 100 genome sequences of Pasteurella multocida are available, comprehensive and complete genome sequence analysis is limited. This study describes the analysis of complete genome sequence and pathogenomics of P. multocida strain PMTB2.1. The genome of PMTB2.1 has 2176 genes with more than 40 coding sequences associated with iron regulation and 140 virulence genes including the complete tad locus. The tad locus includes several previously uncharacterized genes such as flp2, rcpC and tadV genes. A transposable phage resembling to Mu phages was identified in P. multocida that has not been identified in any other serotype yet. The multi-locus sequence typing analysis assigned the PMTB2.1 genome sequence as type ST101, while the comparative genome analysis showed that PMTB2.1 is closely related to other P. multocida strains with the genomic distance of less than 0.13. The expression profiling of iron regulating-genes of PMTB2.1 was characterized under iron-limited environment. Results showed significant changes in the expression profiles of iron-regulating genes (p < 0.05) whereas the highest expression of fecE gene (281 fold) at 30 min suggests utilization of the outer-membrane proteins system in iron acquisition at an early stage of growth. This study showed the phylogenomic relatedness of P. multocida and improved annotation of important genes and functional characterization of iron-regulating genes of importance to the bacterial growth.
  14. Jabeen S, Yong YH, Abdullah FJF, Zakaria Z, Mat Isa N, Tan YC, et al.
    Genome Announc, 2017 Nov 02;5(44).
    PMID: 29097462 DOI: 10.1128/genomeA.01190-17
    Pasteurella multocida causes pneumonic pasteurellosis and hemorrhagic septicemia (HS) in large ruminants. In this study, we determined the complete genome sequence of P. multocida strain PMTB2.1 capsular serotype A isolated from buffaloes that died of septicemia.
  15. Ejyj J, Ang WJ, Wh WH, Tan YC
    Cureus, 2018 Jun 19;10(6):e2835.
    PMID: 30131928 DOI: 10.7759/cureus.2835
    Traumatic optic neuropathy (TON) is a rare devastating complication of traumatic head injury and is an ophthalmic emergency. Herein, we report a rare case of a 46-year-old gentleman who experienced severe blurring of vision, binocular diplopia, and pain over his left eye following a fall from a tree about three meters in height. Examinations revealed the visual acuity was 6/60 with a marked relative afferent pupillary defect and generalized ophthalmoplegia over his left eye. Emergency computed tomography (CT) brain and orbit showed a left frontotemporoparietal extradural hemorrhage, comminuted frontotemporoparietal and greater wing of sphenoid fracture with a bony spur impinging the lateral rectus and indirectly on the optic nerve. A diagnosis of left frontotemporoparietal bone fracture with traumatic optic neuropathy was made. An emergency left craniotomy, elevation of depressed skull fracture, and evacuation of clot was done. Postoperatively, his visual acuity showed marked improvement with visual acuity of 6/6 and all optic nerve functions were normal.
  16. Ho CL, Tan YC, Yeoh KA, Ghazali AK, Yee WY, Hoh CC
    BMC Genomics, 2016;17:66.
    PMID: 26781612 DOI: 10.1186/s12864-016-2368-0
    Basal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively.
  17. Mohan A, Manan K, Tan LS, Tan YC, Chin ST, Ahmad R, et al.
    Int J Infect Dis, 2020 Sep;98:59-66.
    PMID: 32535300 DOI: 10.1016/j.ijid.2020.06.025
    OBJECTIVES: Melioidosis is associated with extremely high case fatality ratios. The aim of this study was to determine whether detection of abdominal visceral abscesses can facilitate diagnosis of melioidosis in children.

    METHODS: We conducted a retrospective analysis of all children who had liver and/or spleen abscesses on abdominal ultrasonography admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2014 until December 2018.

    RESULTS: Fifty-three children had liver and/or spleen abscesses. Spleen abscesses were present in 48 (91%) cases; liver abscesses in 15 (28%). Melioidosis was confirmed by culture in 9 (17%) children; small occult splenic abscesses were present in all cases. In 78% of these cases, the lesions were detected before any positive culture (or serology) results were available. Four (8%) children had bacteriologically-confirmed tuberculosis. Two (4%) had Staphylococcus aureus infection. Of the remaining 38 (72%) culture-negative cases, 36 (95%) had clinical and imaging characteristics similar to that of children with culture-confirmed melioidosis and improved with empirical melioidosis antibiotic therapy.

    CONCLUSIONS: A large number of children in Bintulu Hospital in Sarawak, Malaysia, were found to have spleen abscesses. Melioidosis was the most common etiology identified in these children. Abdominal ultrasonography is extremely useful in facilitating the diagnosis of pediatric melioidosis.

  18. Chan CL, Yew SM, Na SL, Tan YC, Lee KW, Yee WY, et al.
    Genome Announc, 2014;2(2).
    PMID: 24744321 DOI: 10.1128/genomeA.00074-14
    Ochroconis constricta is a soilborne dematiaceous fungus that has never been reported to be associated with human infection. Here we report the first draft genome sequence of strain UM 578, isolated from human skin scraping. The genomic information revealed will contribute to a better understanding of this species.
  19. Chun-Ern Ng D, Liew CH, Tan KK, Lim HY, Zailanalhuddin NEB, Tan SF, et al.
    Pediatr Int, 2023;65(1):e15690.
    PMID: 38037505 DOI: 10.1111/ped.15690
    BACKGROUND: We describe the epidemiology, clinical characteristics, and outcomes of multisystem inflammatory syndrome in children (MIS-C) among children from Negeri Sembilan, Malaysia.

    METHODS: A retrospective, multicentre, observational study was performed among children ≤15 years old who were hospitalized for MIS-C between January 18, 2021 and June 30, 2023. The incidence of MIS-C was estimated using reported SARS-CoV-2 cases and census population data. Descriptive analyses were used to summarize the clinical presentation and outcomes.

    RESULTS: The study included 53 patients with a median age of 5.7 years (IQR 1.8-8.7 years); 75.5% were males. The overall incidence of MIS-C was approximately 5.9 cases per 1,000,000 person-months. Pediatric intensive care unit (PICU) admission was required for 22 (41.5%) patients. No mortalities were recorded. Children aged 6-12 years were more likely to present with cardiac dysfunction/shock (odds ratio [OR] 5.43, 95% confidence interval [CI] 1.67-17.66), whereas children below 6 years were more likely to present with a Kawasaki disease phenotype (OR 5.50, 95% CI 1.33-22.75). Twenty patients (37.7%) presented with involvement of at least four organ systems, but four patients (7.5%) demonstrated single-organ system involvement.

    CONCLUSION: An age-based variation in the clinical presentation of MIS-C was demonstrated. Our findings suggest MIS-C could manifest in a spectrum, including single-organ involvement. Despite the high requirement for PICU admission, the prognosis of MIS-C was favorable, with no recorded mortalities.

  20. Tan YC, Mustangin M, Rosli N, Wan Ahmad Kammal WSE, Md Isa N, Low TY, et al.
    Cryobiology, 2024 Mar;114:104843.
    PMID: 38158171 DOI: 10.1016/j.cryobiol.2023.104843
    Coolant-assisted liquid nitrogen (LN) flash freezing of frozen tissues has been widely adopted to preserve tissue morphology for histopathological annotations in mass spectrometry-based spatial proteomics techniques. However, existing coolants pose health risks upon inhalation and are expensive. To overcome this challenge, we present our pilot study by introducing the EtOH-LN workflow, which demonstrates the feasibility of using 95 % ethanol as a safer and easily accessible alternative to existing coolants for LN-based cryoembedding of frozen tissues. Our study reveals that both the EtOH-LN and LN-only cryoembedding workflows exhibit significantly reduced freezing artifacts compared to cryoembedding in cryostat (p 
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