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Fulltext Quantification of Gait Stability During Incline and Decline Walking: The Responses of Required Coefficient of Friction and Dynamic Postural Index

Abdul Yamin NAA, Basaruddin KS, Abu Bakar S, Salleh AF, Mat Som MH, Yazid H, et al.

J Healthc Eng, 2022;2022:7716821.
PMID: 36275397 DOI: 10.1155/2022/7716821

This study aims to investigate the gait stability response during incline and decline walking for various surface inclination angles in terms of the required coefficient of friction (RCOF), postural stability index (PSI), and center of pressure (COP)-center of mass (COM) distance. A customized platform with different surface inclinations (0°, 5°, 7.5°, and 10°) was designed. Twenty-three male volunteers participated by walking on an inclined platform for each inclination. The process was then repeated for declined platform as well. Qualysis motion capture system was used to capture and collect the trajectories motion of ten reflective markers that attached to the subjects before being exported to a visual three-dimensional (3D) software and executed in Matlab to obtain the RCOF, PSI, as well as dynamic PSI (DPSI) and COP-COM distance parameters. According to the result for incline walking, during initial contact, the RCOF was not affected to inclination. However, it was affected during peak ground reaction force (GRF) starting at 7.5° towards 10° for both walking conditions. The most affected PSI was found at anterior-posterior PSI (APSI) even as low as 5° inclination during both incline and decline walking. On the other hand, DPSI was not affected during both walking conditions. Furthermore, COP-COM distance was most affected during decline walking in anterior-posterior direction. The findings of this research indicate that in order to decrease the risk of falling and manage the inclination demand, a suitable walking strategy and improved safety measures should be applied during slope walking, particularly for decline and anterior-posterior orientations. This study also provides additional understanding on the best incline walking technique for secure and practical incline locomotion.
Fulltext Management of congenital choanal atresia (CCA) after multiple failures: A Case Report

Abdullah A, Abdul Rahman R, Aziz S, Abu Bakar S, AbAziz AA

Med J Malaysia, 2013;68(1):76-8.
PMID: 23466775 MyJurnal

Nasal obstruction in neonates is a potentially fatal condition because neonates are obligatory nasal breathers. Bilateral choanal atresia is therefore a neonatal emergency. Several approaches for corrections of choanal atresia are available including the helium laser: YAG. A 5-year-old Chinese girl born with bilateral choanal atresia, had birth asphyxia that required intubation. She underwent multiple surgeries for correction of choanal atresia at other hospitals but failed to improve. She was referred to Universiti Kebangsaan Malaysia Medical Center (UKMMC) after presenting with intermittent respiratory distress and cyanosis following an upper respiratory tract infection. A repeat computed tomography (CT) scan done preoperatively showed complete bony stenosis over the left choana and finding was confirmed by examination under general anesthesia. She underwent endoscopic transnasal removal of left bony atretic plate. There was no intra or postoperative complications. During follow up 10 years later, the airway on both sides remains patent.
Fulltext Doctor's attire and patient safety

Abu Bakar S

Med J Malaysia, 2009 Sep;64(3):185-6.
PMID: 20527264 MyJurnal

Koh and others have reported (in this issue of the MJM) the high prevalence of Methicillin resistant Staphylococcus aureus (MRSA) on doctors’ neckties. As they have pointed out, this is nothing new, and like other studies with similar findings. They also point out that patient’s confidence and satisfaction are not affected by doctor’s not wearing neckties. They also referred to the British Department of Health decision to ban the use of neckties, long sleeve shirts and jewellery, and the Scottish government’s intention to ban the wearing of white coats, including neckties, to stop the spread of infections. They support the call by The Malaysian Medical Association to avoid the use of neckties.
Fulltext DNA-seq analysis of Garcinia mangostana

Abu Bakar S, Sampathrajan S, Loke KK, Goh HH, Mohd Noor N

Genom Data, 2016 Mar;7:62-3.
PMID: 26981362 DOI: 10.1016/j.gdata.2015.11.018

Mangosteen (Garcinia mangostana Linn.) is a tropical tree mainly found in South East Asia and considered as "the queen of fruits". The asexually produced fruit is dark purple or reddish in color, with white flesh which is slightly acidic with sweet flavor and a pleasant aroma. The purple pericarp tissue is rich in xanthones which are useful for medical purposes. We performed the first genome sequencing of this commercially important fruit tree to study its genome composition and attempted draft genome assembly. Raw reads of the DNA sequencing project have been deposited to SRA database with the accession number SRX1426419.
Fulltext Induction of apoptosis in neurogenic pulmonary edema

Abu Bakar S, Shafee N, Chee HY

Med J Malaysia, 1999 Sep;54(3):402-3.
PMID: 11045072
Fulltext Re-emergence of dengue 4 virus

Abu Bakar S, Wong PF

Med J Malaysia, 2002 Jun;57(2):242-3.
PMID: 24326663
Seeking representation in policy-making governmental bodies

Abu Bakar S

Malays J Pathol, 1997 Dec;19(2):93-7.
PMID: 10879247
Fulltext DNA shotgun sequencing analysis of Garcinia mangostana L. variety Mesta

Abu Bakar S, Kumar S, Loke KK, Goh HH, Mohd Noor N

Genom Data, 2017 Jun;12:118-119.
PMID: 28516035 DOI: 10.1016/j.gdata.2017.05.001

Mangosteen (Garcinia mangostana Linn.) is an ultra-tropical tree characterized by its unique dark purple fruits with white flesh. The xanthone-rich purple pericarp tissue contains valuable compounds with medicinal properties. Following previously reported genome sequencing of a common variety of mangosteen [1], we performed another whole genome sequencing of a commercially popular variety of this fruit species (var. Mesta) for comparative analysis of its genome composition. Raw reads of the DNA sequencing project were deposited to SRA database with the accession number SRX2709728.
Carbon nanotubes from waste cooking palm oil as adsorbent materials for the adsorption of heavy metal ions

Abu Bakar S, Jusoh N, Mohamed A, Muqoyyanah M, Othman MHD, Mamat MH, et al.

Environ Sci Pollut Res Int, 2021 Dec;28(46):65171-65187.
PMID: 34231144 DOI: 10.1007/s11356-021-14918-y

In this work, waste cooking palm oil (WCPO)-based carbon nanotubes (CNTs) with encapsulated iron (Fe) nanoparticles have been successfully produced via modified thermal chemical vapor deposition method. Based on several characterizations, the dense WCPO-based CNT was produced with high purity of 89% and high crystallinity proven by low ID/IG ratio (0.43). Moreover, the ferromagnetic response of CNTs showed that the average coercivity and magnetization saturation were found to be 551.5 Oe and 13.4 emu/g, respectively. These produced WCPO-based CNTs were further used as heavy metal ions adsorbent for wastewater treatment application. Some optimizations, such as the effect of different adsorbent dosage, varied initial pH solution, and various heavy metal ions, were investigated. The adsorption studies showed that the optimum adsorbent dosage was 1.8 g/L when it was applied to 100 mg/L Cu (II) solution at neutral pH (pH 7). Further measurement then showed that high Cu (II) ion removal percentage (~80%) was achieved when it was applied at very acidic solution (pH 2). Last measurement confirmed that the produced WCPO-based CNTs successfully removed different heavy metal ions in the following order: Fe (II) > Zn (II) ≈ Cu (II) with the removal percentage in the range of 99.2 to 99.9%. The adsorption isotherm for Cu (II) was better fitted by Langmuir model with a correlation coefficient of 0.82751. WCPO-based CNTs can be a potential material to be applied as adsorbent in heavy metal ion removal.
Comparative study of synthesised hyroxyapatite from pure chemicals and Malaysian natural limestone precursors

Abu Bakar SH, Hussein Z, Hee SL, Fazan F

Med J Malaysia, 2004 May;59 Suppl B:81-2.
PMID: 15468829

Hydroxyapatite, (HA; Ca1O(PO4)6(OH)2) has been successfully applied in medical and dental applications for several years due to its excellent biocompatibility. The usage of HA in Malaysia, however, is limited due to the lack of availability. Therefore the aim of this work is to produce HA materials from both pure chemicals and from Malaysian natural limestone precursors, and to compare their bulk properties. However, parts of Malaysian natural limestone deposits actually consist of a combination of Ca(OH)2 and CaCO3. In order to utilise the limestone to produce HA material, the combination of these commercially pure chemicals as HA precursors should still work. In order to test this hypothesis, two HAs were produced by wet synthesis technique utilising (a) combination of Ca(OH)2 + CaCO3 from pure commercial chemicals [WCC] and (b) a local natural limestone [WL] precursors. The HAs produced; WCC and WL, were compacted into discs and sintered at 1250 degrees C. The characterisations and evaluations conducted were XRD, SEM-EDX, FTIR and shrinkage factor. The results indicate that WL gives slightly better bulk properties compared to WCC.
Stature Estimation from Lower Limb Anthropometry using Linear Regression Analysis: A Study on the Malaysian Population

Abu Bakar SN, Aspalilah A, AbdelNasser I, Nurliza A, Hairuliza MJ, Swarhib M, et al.

Clin Ter, 2017 Mar-Apr;168(2):e84-e87.
PMID: 28383619 DOI: 10.7417/CT.2017.1988

INTRODUCTION: Stature is one of the characteristics that could be used to identify human, besides age, sex and racial affiliation. This is useful when the body found is either dismembered, mutilated or even decomposed, and helps in narrowing down the missing person's identity.

AIM: The main aim of the present study was to construct regression functions for stature estimation by using lower limb bones in the Malaysian population.

MATERIALS AND METHODS: The sample comprised 87 adult individuals (81 males, 6 females) aged between 20 to 79 years. The parameters such as thigh length, lower leg length, leg length, foot length, foot height and foot breadth were measured. They were measured by a ruler and measuring tape. Statistical analysis involved independent t-test to analyse the difference between lower limbs in male and female. The Pearson's correlation test was used to analyse correlations between lower limb parameters and stature, and the linear regressions were used to form equations. The paired t-test was used to compare between actual stature and estimated stature by using the equations formed.

RESULTS: Using independent t-test, there was a significant difference (p< 0.05) in the measurement between males and females with regard to leg length, thigh length, lower leg length, foot length and foot breadth. The thigh length, leg length and foot length were observed to have strong correlations with stature with p= 0.75, p= 0.81 and p= 0.69, respectively. Linear regressions were formulated for stature estimation. Paired t-test showed no significant difference between actual stature and estimated stature.

CONCLUSIONS: It is concluded that regression functions can be used to estimate stature to identify skeletal remains in the Malaysia population.
Fulltext Oviposition deterring and oviciding potentials of Ipomoea cairica L. leaf extract against dengue vectors

Ahbirami R, Zuharah WF, Yahaya ZS, Dieng H, Thiagaletchumi M, Fadzly N, et al.

Trop Biomed, 2014 Sep;31(3):456-65.
PMID: 25382472

Bioprospecting of plant-based insecticides for vector control has become an area of interest within the last two decades. Due to drawbacks of chemical insecticides, phytochemicals of plant origin with mosquito control potential are being utilized as alternative sources in integrated vector control. In this regard, the present study aimed to investigate oviposition deterring and oviciding potentials of Ipomoea cairica (L.) (Family: Convolvulaceae) crude leaf extract against dengue vectors, Aedes aegypti and Aedes albopictus. Ipomoea cairica is an indigenous plant that has demonstrated marked toxicity towards larvae of Ae. aegypti and Ae. albopictus. Leaves of I. cairica were extracted using Soxhlet apparatus with acetone as solvent. Oviposition deterrent activity and ovicidal assay was carried out in oviposition site choice tests with three different concentrations (50, 100, 450 ppm). Acetone extract of I. cairica leaf strongly inhibited oviposition with 100% repellence to Ae. aegypti at lower concentration of 100 ppm, while for Ae. albopictus was at 450 ppm. The oviposition activity index (OAI) values which ranged from -0.69 to -1.00 revealed that I. cairica demonstrated deterrent effect. In ovicidal assay, similar trend was observed whereby zero hatchability was recorded for Ae. aegypti and Ae. albopictus eggs at 100 and 450 ppm, respectively. It is noteworthy that I. cairica leaf extract had significantly elicited dual properties as oviposition deterrent and oviciding agent in both Aedes species. Reduction in egg number through oviposition deterring activity, reduction in hatching percentage and survival rates, suggested an additional hallmark of this plant to be integrated in Aedes mosquito control. Ipomoea cairica deserved to be considered as one of the potential alternative sources for the new development of novel plant based insecticides in future.
Fulltext Effect of Carcinomas on Autosomal Trait Screening: A Review Article

Alhatim H, Abdullah MNH, Abu Bakar S, Amer SA

Curr Issues Mol Biol, 2023 Sep 04;45(9):7275-7285.
PMID: 37754244 DOI: 10.3390/cimb45090460

This review highlights the effect of carcinomas on the results of the examination of autosomal genetic traits for identification and paternity tests when carcinoid tissue is the only source and no other samples are available. In DNA typing or genetic fingerprinting, variable elements are isolated and identified within the base pair sequences that form the DNA. The person's probable identity can be determined by analysing nucleotide sequences in particular regions of DNA unique to everyone. Genetics plays an increasingly important role in the risk stratification and management of carcinoma patients. The available information from previous studies has indicated that in some incidents, including mass disasters and crimes such as terrorist incidents, biological evidence may not be available at the scene of the accident, except for some unknown human remains found in the form of undefined human tissues. If these tissues have cancerous tumours, it may affect the examination of the genetic traits derived from these samples, thereby resulting in a failure to identify the person. Pathology units, more often, verify the identity of the patients who were diagnosed with cancer in reference to their deceased tumorous relatives. Genetic fingerprinting (GF) is also used in paternity testing when the alleged parent disappeared or died and earlier was diagnosed and treated for cancer.
Electrochemical exfoliation of graphite in nanofibrillated kenaf cellulose (NFC)/surfactant mixture for the development of conductive paper

Ardyani T, Mohamed A, Abu Bakar S, Sagisaka M, Umetsu Y, Hafiz Mamat M, et al.

Carbohydr Polym, 2020 Jan 15;228:115376.
PMID: 31635739 DOI: 10.1016/j.carbpol.2019.115376

The effect of incorporating common dodecyl anionic and cationic surfactants such as dodecyltrimethylammonium bromide (DTAB), dodecylethyldimethylammonium bromide (DDAB), and sodium dodecylsulfate (SDS) in nanocomposites of reduced graphene oxide and nanocellulose are described. The stabilization and electrical properties of the nanocomoposites of reduced graphene oxide (RGO) and nanofibrillated kenaf cellulose (NFC) were characterized using four-point probe electrical conductivity measurements. Raman spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy were used to investigate dispersion morphology and the quality of RGO inside the NFC matrices. Small-angle neutron scattering (SANS) was used to study the aggregation behavior of the aqueous surfactant systems and RGO dispersions. The cationic surfactant DTAB proved to be the best choice for stabilization of RGO in NFC, giving enhanced electrical conductivity five orders of magnitude higher than the neat NFC. The results highlight the effects of hydrophilic surfactant moieties on the structure, stability and properties of RGO/NFC composites.
Fulltext Virucidal activity of Virkon S on human enterovirus

Chan YF, Abu Bakar S

Med J Malaysia, 2005 Jun;60(2):246-8.
PMID: 16114171

The efficacy of Virkon S, a commercial disinfectant as a virucidal spray against human enterovirus 71 (HEV71), the causative agent of the fatal form of hand, foot and mouth disease was examined. At least one log10 reduction of HEV71 titer was achieved when one spray of Virkon (1% or 2%) with ten minutes of contact time was applied. The infectivity was completely lost when four sprays of 1% or 2% Virkon were applied, suggesting that at least four sprays of 1% Virkon to the surface bound HEV71 was necessary to completely inactivate the virus. These findings suggest that Virkon S at the proper concentration is suitable to be used as an effective and easy to use disinfectant against HEV71.
Ultrastructural changes of cell morphology and viral morphogenesis of two ecotypes of dengue virus infection in human monocytic U-937 cell

Fish-Low CY, Abu Bakar S, Othman F, Chee HY

Trop Biomed, 2018 Dec 01;35(4):1154-1159.
PMID: 33601863

Dengue virus (DENV) is maintained and circulated in both sylvatic/enzootic and endemic/human cycles and spill over infection of sylvatic DENV into human populations has been reported. Extensive deforestation and increase human activities in forest may increase the risk of human exposure to sylvatic dengue infection and this may become a threat to human. Present study investigated the changes in cell morphology and viral morphogenesis upon infection with sylvatic and endemic ecotypes in human monocytic U-937 cells using transmission electron microscopy. Autophagy, a process that is either pro-viral or anti-viral, was observed in U-937 cells of both infections, however only the replication of endemic DENV was evidenced. An insight into the infection responses of sylvatic progenitors of DENV in susceptible host cells may provide better understanding on dengue emergence in human populations.
Fulltext A comparison of assays for accurate copy number measurement of the low-affinity Fc gamma receptor genes FCGR3A and FCGR3B

Haridan US, Mokhtar U, Machado LR, Abdul Aziz AT, Shueb RH, Zaid M, et al.

PLoS One, 2015;10(1):e0116791.
PMID: 25594501 DOI: 10.1371/journal.pone.0116791

The FCGR3 locus encoding the low affinity activating receptor FcγRIII, plays a vital role in immunity triggered by cellular effector and regulatory functions. Copy number of the genes FCGR3A and FCGR3B has previously been reported to affect susceptibility to several autoimmune diseases and chronic inflammatory conditions. However, such genetic association studies often yield inconsistent results; hence require assays that are robust with low error rate. We investigated the accuracy and efficiency in estimating FCGR3 CNV by comparing Sequenom MassARRAY and paralogue ratio test-restriction enzyme digest variant ratio (PRT-REDVR). In addition, since many genetic association studies of FCGR3B CNV were carried out using real-time quantitative PCR, we have also included the evaluation of that method's performance in estimating the multi-allelic CNV of FCGR3B. The qPCR assay exhibited a considerably broader distribution of signal intensity, potentially introducing error in estimation of copy number and higher false positive rates. Both Sequenom and PRT-REDVR showed lesser systematic bias, but Sequenom skewed towards copy number normal (CN = 2). The discrepancy between Sequenom and PRT-REDVR might be attributed either to batch effects noise in individual measurements. Our study suggests that PRT-REDVR is more robust and accurate in genotyping the CNV of FCGR3, but highlights the needs of multiple independent assays for extensive validation when performing a genetic association study with multi-allelic CNVs.
Improving the (18)F-fluoromethylcholine ((18)F-FCH) radiochemical yield via optimising the azeotropic drying of non-carrier-added (18)F-fluorine

Hassan H, Abu Bakar S, Halim KN, Idris J, Ahmad Saad FF, Nordin AJ

J Labelled Comp Radiopharm, 2015 Sep-Oct;58(11-12):458-9.
PMID: 26395258 DOI: 10.1002/jlcr.3347

(18)F-Fluoromethylcholine ((18)F-FCH) has been suggested as one of the reputable imaging tracers for diagnosis of prostate tumour in PET/CT examination. Nevertheless, it has never been synthesised in Malaysia. We acknowledged the major problem with (18)F-FCH is due to its relatively low radiochemical yield at the end of synthesis (EOS). Therefore, this technical note presents improved (18)F-FCH radiochemical yields after carrying out optimisation on azeotropic drying of non-carrier-added (18)F-Fluorine.
Convenient and Efficient Method for Quality Control Analysis of 18F-Fluorocholine: For a Small Scale GMP-based Radiopharmaceuticals Laboratory Set-up

Hassan H, Abu Bakar S, Halim KN, Idris J, Nordin AJ

Curr Radiopharm, 2016;9(2):128-36.
PMID: 26013570

BACKGROUND AND OBJECTIVE: Prostate cancer continues to be the most prevalent cancer in men in Malaysia. As time progresses, the prospect of PET imaging modality in diagnosis of prostate cancer is promising, with on-going improvement on novel tracers. Among all tracers, 18F-Fluorocholine is reported to be a reputable tracer and reliable diagnostic technique for prostate imaging. Nonetheless, only 18F-Fluorodeoxyglucose (18F-FDG) is available and used in most oncology cases in Malaysia. With a small scale GMP-based radiopharmaceuticals laboratory set-up, initial efforts have been taken to put Malaysia on 18F-Fluorocholine map. This article presents a convenient, efficient and reliable method for quality control analysis of 18F-Fluorocholine. Besides, the aim of this research work is to assist local GMP radiopharmaceuticals laboratories and local authority in Malaysia for quality control analysis of 18F-Fluorocholine guideline.
METHODS: In this study, prior to synthesis, quality control analysis method for 18F-Fluorocholine was developed and validated, by adapting the equipment set-up used in 18F-Fluorodeoxyglucose (18FFDG) routine production. Quality control on the 18F-Fluorocholine was performed by means of pH, radionuclidic identity, radio-high performance liquid chromatography equipped with ultraviolet, radio- thin layer chromatography, gas chromatography and filter integrity test.
RESULTS: Post-synthesis; the pH of 18F-Fluorocholine was 6.42 ± 0.04, with half-life of 109.5 minutes (n = 12). The radiochemical purity was consistently higher than 99%, both in radio-high performance liquid chromatography equipped with ultraviolet (r-HPLC; SCX column, 0.25 M NaH2PO4: acetonitrile) and radio-thin layer chromatography method (r-TLC). The calculated relative retention time (RRT) in r-HPLC was 1.02, whereas the retention factor (Rf) in r-TLC was 0.64. Potential impurities from 18F-Fluorocholine synthesis such as ethanol, acetonitrile, dimethylethanolamine and dibromomethane were determined in gas chromatography. Using our parameters, (capillary column: DB-200, 30 m x 0.53 mm x 1 um) and oven temperature of 35°C (isothermal), all compounds were well resolved and eluted within 3 minutes. Level of ethanol and acetonitrile in 18F-Fluorocholine were detected below threshold limit; less than 5 mg/ml and 0.41 mg/ml respectively. Meanwhile, dimethylethanolamine and dibromomethane were undetectable.
CONCLUSION: A convenient, efficient and reliable quality control analysis work-up procedure for 18FFluorocholine has been established and validated to comply all the release criteria. The convenient method of quality control analysis may provide a guideline to local GMP radiopharmaceutical laboratories to start producing 18F-Fluorocholine as a tracer for prostate cancer imaging.
Exploring the in vitro potential of celecoxib derivative AR-12 as an effective antiviral compound against four dengue virus serotypes

Hassandarvish P, Oo A, Jokar A, Zukiwski A, Proniuk S, Abu Bakar S, et al.

J Antimicrob Chemother, 2017 09 01;72(9):2438-2442.
PMID: 28666323 DOI: 10.1093/jac/dkx191

Objectives: With no clinically effective antiviral options available, infections and fatalities associated with dengue virus (DENV) have reached an alarming level worldwide. We have designed this study to evaluate the efficacy of the celecoxib derivative AR-12 against the in vitro replication of all four DENV serotypes.
Methods: Each 24-well plate of Vero cells infected with all four DENV serotypes, singly, was subjected to treatments with various doses of AR-12. Following 48 h of incubation, inhibitory efficacies of AR-12 against the different DENV serotypes were evaluated by conducting a virus yield reduction assay whereby DENV RNA copy numbers present in the collected supernatant were quantified using qRT-PCR. The underlying mechanism(s) possibly involved in the compound's inhibitory activities were then investigated by performing molecular docking on several potential target human and DENV protein domains.
Results: The qRT-PCR data demonstrated that DENV-3 was most potently inhibited by AR-12, followed by DENV-1, DENV-2 and DENV-4. Our molecular docking findings suggested that AR-12 possibly exerted its inhibitory effects by interfering with the chaperone activities of heat shock proteins.
Conclusions: These results serve as vital information for the design of future studies involving in vitro mechanistic studies and animal models, aiming to decipher the potential of AR-12 as a potential therapeutic option for DENV infection.

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