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Probing the anti-Aβ42 aggregation and protective effects of prenylated xanthone against Aβ42-induced toxicity in transgenic Caenorhabditis elegans model

Thew HY, Boon Keat K, Tan YC, Ong YS, Parat MO, Murugaiyah V, et al.

Chem Biol Interact, 2024 Mar 28;394:110978.
PMID: 38552766 DOI: 10.1016/j.cbi.2024.110978

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) protein aggregates, leading to synaptic dysfunction and neuronal cell death. In this study, we used a comprehensive approach encompassing in vitro assays, computational analyses, and an in vivo Caenorhabditis elegans model to evaluate the inhibitory effects of various xanthones, focusing on Garcinone D (GD), on Aβ42 oligomer formation. Dot blot analysis revealed concentration-dependent responses among xanthones, with GD consistently inhibiting Aβ42 oligomer formation at low concentrations (0.1 and 0.5 μM, inhibitions of 84.66 ± 2.25% and 85.06 ± 6.57%, respectively). Molecular docking and dynamics simulations provided insights into the molecular interactions between xanthones and Aβ42, highlighting the disruption of key residues involved in Aβ42 aggregation. The neuroprotective potential of GD was established using transgenic C. elegans GMC101, with substantial delays in paralysis reported at higher concentrations. Our findings show that GD is a potent suppressor of Aβ42 oligomer formation, suggesting its potential as a therapeutic candidate for AD. The concentration-dependent effects observed in both in vitro and in vivo models underscore the need for nuanced dose-response assessments. These findings contribute novel insights into the therapeutic landscape of xanthones against AD, emphasizing the multifaceted potential of GD for further translational endeavors in neurodegenerative disorder research.
EtOH-LN cryoembedding workflow to minimize freezing artifact in frozen tissues: A pilot study in preparing tissues compatible with mass spectrometry-based spatial proteomics application

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
Fulltext A Systematic Stereo Camera Calibration Strategy: Leveraging Latin Hypercube Sampling and 2k Full-Factorial Design of Experiment Methods

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.
Comparative genomic and phenotypic analyses of pathogenic fungi Neoscytalidium dimidiatum and Bipolaris papendorfii isolated from human skin scraping

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.
Prevalence of COVID-19 among healthcare workers in the paediatric department: Estimates from a multicenter cross-sectional survey in Negeri Sembilan

David NCE, Juliana H, Chok M, Gan YZ, Tan YC, Nur Adlina MN, et al.

Med J Malaysia, 2023 Jan;78(1):80-86.
PMID: 36715196

INTRODUCTION: The COVID-19 pandemic has reached a phase where many have been infected at least once. Healthcare workers were not spared from being infected. This study aimed to determine the period prevalence of COVID-19 among the paediatric healthcare workers in Negeri Sembilan as the country transitioned into an endemic phase of the pandemic. Additionally, we investigate potential sociodemographic and occupational characteristics associated with SARS-CoV-2 infection among healthcare workers.
MATERIALS AND METHODS: A cross-sectional study was conducted among the healthcare workers in the paediatric department at three public specialist hospitals in Negeri Sembilan between 15 and 21 April 2022. Data were collected through a self-administered questionnaire.
RESULTS: Out of the 504 eligible healthcare workers, 493 participated in this study (response rate 97.8%). The overall prevalence of COVID-19 (11 March 2020-15 April 2022) among healthcare workers was 50.9%. The majority (80.1%) were infected during the Omicron wave two months before the survey. Household contacts accounted for 35.9% of infection sources. The proportion of non-doctors in the COVID-19-infected group was significantly higher compared to the non-infected group (74.1% vs 64.0%, p=0.016). The COVID-19-infected group had a higher proportion of schoolgoing children (44.6% vs 30.6%, p=0.001) and children who attended pre-school/sent to the babysitter (49.0% vs 24.4%, p<0.001). There were no significant differences between infection rates among the healthcare workers working in the tertiary hospital and the district hospitals. There were also no significant differences in the proportion of COVID-19- infected doctors and nurses when analysed by seniority.
CONCLUSION: Our study provided an estimate on the prevalence of COVID-19 among paediatric healthcare workers in Negeri Sembilan and the factors associated with infection, which captures the extent and magnitude of this pandemic on the state's paediatric department. Most infections resulted from household contact, with a higher proportion of infected healthcare workers having young children.
Epidemiology, clinical characteristics and outcomes of multisystem inflammatory syndrome in children

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.
Fulltext Predicting Deleterious Non-Synonymous Single Nucleotide Polymorphisms (nsSNPs) of HRAS Gene and In Silico Evaluation of Their Structural and Functional Consequences towards Diagnosis and Prognosis of Cancer

Chai CY, Maran S, Thew HY, Tan YC, Rahman NMANA, Cheng WH, et al.

Biology (Basel), 2022 Nov 02;11(11).
PMID: 36358305 DOI: 10.3390/biology11111604

The Harvey rat sarcoma (HRAS) proto-oncogene belongs to the RAS family and is one of the pathogenic genes that cause cancer. Deleterious nsSNPs might have adverse consequences at the protein level. This study aimed to investigate deleterious nsSNPs in the HRAS gene in predicting structural alterations associated with mutants that disrupt normal protein-protein interactions. Functional and structural analysis was employed in analyzing the HRAS nsSNPs. Putative post-translational modification sites and the changes in protein-protein interactions, which included a variety of signal cascades, were also investigated. Five different bioinformatics tools predicted 33 nsSNPs as "pathogenic" or "harmful". Stability analysis predicted rs1554885139, rs770492627, rs1589792804, rs730880460, rs104894227, rs104894227, and rs121917759 as unstable. Protein-protein interaction analysis revealed that HRAS has a hub connecting three clusters consisting of 11 proteins, and changes in HRAS might cause signal cascades to dissociate. Furthermore, Kaplan-Meier bioinformatics analyses indicated that the HRAS gene deregulation affected the overall survival rate of patients with breast cancer, leading to prognostic significance. Thus, based on these analyses, our study suggests that the reported nsSNPs of HRAS may serve as potential targets for different proteomic studies, diagnoses, and therapeutic interventions focusing on cancer.
Fulltext A scaffolded approach to unearth potential antibacterial components from epicarp of Malaysian Nephelium lappaceum L

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.
Fulltext Metabolite Profiling of Malaysian Gracilaria edulis Reveals Eplerenone as Novel Antibacterial Compound for Drug Repurposing Against MDR Bacteria

Asghar A, Tan YC, Shahid M, Yow YY, Lahiri C

Front Microbiol, 2021;12:653562.
PMID: 34276590 DOI: 10.3389/fmicb.2021.653562

With a continuous threat of antimicrobial resistance on human health worldwide, efforts for new alternatives are ongoing for the management of bacterial infectious diseases. Natural products of land and sea, being conceived to be having fewer side effects, pose themselves as a welcome relief. In this respect, we have taken a scaffolded approach to unearthing the almost unexplored chemical constituents of Malaysian red seaweed, Gracilaria edulis. Essentially, a preliminary evaluation of the ethyl acetate and acetone solvent extracts, among a series of six such, revealed potential antibacterial activity against six MDR species namely, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, and Bacillus subtilis. Detailed analyses of the inlying chemical constituents, through LC-MS and GC-MS chromatographic separation, revealed a library of metabolic compounds. These were led for further virtual screening against selected key role playing proteins in the virulence of the aforesaid bacteria. To this end, detailed predictive pharmacological analyses added up to reinforce Eplerenone as a natural alternative from the plethora of plausible bioactives. Our work adds the ongoing effort to re-discover and repurpose biochemical compounds to combat the antimicrobial resistance offered by the Gram-positive and the -negative bacterial species.
Fulltext Detection of spleen abscesses facilitates diagnosis of melioidosis in Malaysian children

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.
Polyhydroxyalkanoate (PHA) synthase genes and PHA-associated gene clusters in Pseudomonas spp. and Janthinobacterium spp. isolated from Antarctica

Tan IKP, Foong CP, Tan HT, Lim H, Zain NA, Tan YC, et al.

J Biotechnol, 2020 Apr 10;313:18-28.
PMID: 32171790 DOI: 10.1016/j.jbiotec.2020.03.006

The polyhydroxyalkanoate (PHA) producing capability of four bacterial strains isolated from Antarctica was reported in a previous study. This study analyzed the PHA synthase genes and the PHA-associated gene clusters from the two antarctic Pseudomonas isolates (UMAB-08 and UMAB-40) and the two antarctic Janthinobacterium isolates (UMAB-56 and UMAB-60) through whole-genome sequence analysis. The Pseudomonas isolates were found to carry PHA synthase genes which fall into two different PHA gene clusters, namely Class I and Class II, which are involved in the biosynthesis of short-chain-length-PHA (SCL-PHA) and medium-chain-length-PHA (MCL-PHA), respectively. On the other hand, the Janthinobacterium isolates carry a Class I and an uncharacterized putative PHA synthase genes. No other gene involved in PHA synthesis was detected in close proximity to the uncharacterized putative PHA synthase gene in the Janthinobacterium isolates, therefore it falls into a separate clade from the ordinary Class I, II, III and IV clades of PHA synthase (PhaC) phylogenetic tree. Multiple sequence alignment showed that the uncharacterized putative PHA synthase gene contains all the highly conserved amino acid residues and the proposed catalytic triad of PHA synthase. PHA biosynthesis and in vitro PhaC enzymatic assay results showed that this uncharacterized putative PHA synthase from Janthinobacterium sp. UMAB-60 is funtional. This report adds new knowledge to the PHA synthase database as we describe scarce information of PHA synthase genes and PHA-associated gene clusters from the antarctic bacterial isolates (extreme and geographically isolated environment) and comparing with those from non-antarctic PHA-producing bacteria.
Cerebral venous sinus thrombosis: review of cases in a single centre in Malaysia

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.
Fulltext Apocynin and catalase prevent hypertension and kidney injury in Cyclosporine A-induced nephrotoxicity in rats

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.
Fulltext Invasive Salmonella infections among children in Bintulu, Sarawak, Malaysian Borneo: a 6-year retrospective review

Mohan A, Munusamy C, Tan YC, Muthuvelu S, Hashim R, Chien SL, et al.

BMC Infect Dis, 2019 Apr 18;19(1):330.
PMID: 30999894 DOI: 10.1186/s12879-019-3963-x

BACKGROUND: Invasive Salmonella infections result in significant morbidity and mortality in developing countries. In Asia, typhoid and paratyphoid fever are reported to be the major invasive Salmonella infections, while invasive non-typhoidal Salmonella (iNTS) infections are believed to be uncommon. Data from Sarawak, in Malaysian Borneo, are limited.
METHODS: A retrospective study identifying all children aged
Fulltext Complete Genome Sequence Analysis and Characterization of Selected Iron Regulation Genes of Pasteurella Multocida Serotype A Strain PMTB2.1

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.
Fulltext Craniotomy Improves Traumatic Optic Neuropathy

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.
Fulltext Complete Genome Sequence of Pasteurella multocida Serotype A Strain PMTB2.1 Isolated from Buffaloes That Died of Septicemia in Malaysia

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.
Fulltext Geographical distribution of Brucella melitensis inferred from rpoB gene variation

Tan KK, Tan YC, Chang LY, Lee KW, Nor'e SS, Yee WY, et al.

J Infect Dev Ctries, 2017 Jun 01;11(5):420-425.
PMID: 30943180 DOI: 10.3855/jidc.7598

INTRODUCTION: Currently available tests have limitations for the identification of Brucella species and strains, and their genetic lineage. The genome sequence of the rpoB gene encoding the β-subunit of DNA-dependent RNA polymerase was investigated for its use in genotyping Brucella melitensis.
METHODOLOGY: Complete rpoB gene sequences of globally distributed Brucella melitensis strains were analyzed. Single nucleotides polymorphisms (SNPs) of the rpoB gene sequences were identified and used to type Brucella melitensis strains.
RESULTS: Six DNA polymorphisms were identified, of which two (nucleotides 3201 and 558) were novel. Analysis of the geographical distribution of the strains revealed a spatial clustering pattern with rpoB type 1 representing European and American strains, rpoB type 2 representing European, African, and Asian strains, rpoB type 3 representing Mediterranean strains, and rpoB type 4 representing African (C3201T) and European (C3201T/T558A) strains.
CONCLUSIONS: We report the discovery of two novel SNPs of rpoB gene that can serve as useful markers for epidemiology and geographical tracking of B. melitensis.
Transfrontal Transaqueductal, Transtrigonal, and Suboccipital Infratentorial Supracerebellar Endoscopic Fenestration of Posterior Fossa Arachnoid Cysts: Three Surgical Cases

Idris Z, Tan YC, Kandasamy R, Ghani RI, Abdullah JM

J Neurol Surg A Cent Eur Neurosurg, 2017 Mar;78(2):210-215.
PMID: 26968147 DOI: 10.1055/s-0035-1571161

Symptomatic intracranial arachnoid cysts are commonly treated using neuroendoscopy. Cysts located within the posterior fossa may present a greater surgical challenge to the neurosurgeon due to the numerous vital neurovascular structures located within this confined space. Adding neuronavigation during endoscopy helps a neurosurgeon to visualize and utilize both anterior and posterior corridors safely to access and manage these lesions. We present three symptomatic posterior fossa arachnoid cysts that were treated successfully using minimally invasive neuronavigation-guided endoscopic neurosurgery utilizing the anterior transfrontal transaqueductal, anterior transfrontal transtrigonal, and posterior suboccipital infratentorial supracerebellar approaches.
Fulltext Genomic insight into pathogenicity of dematiaceous fungus Corynespora cassiicola

Looi HK, Toh YF, Yew SM, Na SL, Tan YC, Chong PS, et al.

PeerJ, 2017;5:e2841.
PMID: 28149676 DOI: 10.7717/peerj.2841

Corynespora cassiicola is a common plant pathogen that causes leaf spot disease in a broad range of crop, and it heavily affect rubber trees in Malaysia (Hsueh, 2011; Nghia et al., 2008). The isolation of UM 591 from a patient's contact lens indicates the pathogenic potential of this dematiaceous fungus in human. However, the underlying factors that contribute to the opportunistic cross-infection have not been fully studied. We employed genome sequencing and gene homology annotations in attempt to identify these factors in UM 591 using data obtained from publicly available bioinformatics databases. The assembly size of UM 591 genome is 41.8 Mbp, and a total of 13,531 (≥99 bp) genes have been predicted. UM 591 is enriched with genes that encode for glycoside hydrolases, carbohydrate esterases, auxiliary activity enzymes and cell wall degrading enzymes. Virulent genes comprising of CAZymes, peptidases, and hypervirulence-associated cutinases were found to be present in the fungal genome. Comparative analysis result shows that UM 591 possesses higher number of carbohydrate esterases family 10 (CE10) CAZymes compared to other species of fungi in this study, and these enzymes hydrolyses wide range of carbohydrate and non-carbohydrate substrates. Putative melanin, siderophore, ent-kaurene, and lycopene biosynthesis gene clusters are predicted, and these gene clusters denote that UM 591 are capable of protecting itself from the UV and chemical stresses, allowing it to adapt to different environment. Putative sterigmatocystin, HC-toxin, cercosporin, and gliotoxin biosynthesis gene cluster are predicted. This finding have highlighted the necrotrophic and invasive nature of UM 591.

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