Displaying publications 1 - 20 of 36 in total

Abstract:
Sort:
  1. Ganasegeran K, Ch'ng ASH, Aziz ZA, Looi I
    Sci Rep, 2020 Jul 09;10(1):11353.
    PMID: 32647336 DOI: 10.1038/s41598-020-68335-1
    Stroke has emerged as a major public health concern in Malaysia. We aimed to determine the trends and temporal associations of real-time health information-seeking behaviors (HISB) and stroke incidences in Malaysia. We conducted a countrywide ecological correlation and time series study using novel internet multi-timeline data stream of 6,282 hit searches and conventional surveillance data of 14,396 stroke cases. We searched popular search terms related to stroke in Google Trends between January 2004 and March 2019. We explored trends by comparing average relative search volumes (RSVs) by month and weather through linear regression bootstrapping methods. Geographical variations between regions and states were determined through spatial analytics. Ecological correlation analysis between RSVs and stroke incidences was determined via Pearson's correlations. Forecasted model was yielded through exponential smoothing. HISB showed both cyclical and seasonal patterns. Average RSV was significantly higher during Northeast Monsoon when compared to Southwest Monsoon (P 
  2. Aziz ZA, Noordin NM, Wan Mohd WM, Kasim MA
    PLoS One, 2023;18(2):e0279882.
    PMID: 36763619 DOI: 10.1371/journal.pone.0279882
    Diagnosis and treatment of tuberculosis infection (TBI) are the core elements of tuberculosis elimination. Interferon gamma release assays have advantages over the tuberculin skin test, although their implementation in low-resource settings is challenging. The performance of a novel digital lateral flow assay QIAreach® QuantiFERON®-TB (QIAreach QFT) against the QuantiFERON®-TB Gold Plus (QFT-Plus) assay was evaluated in an intermediate incidence setting (Malaysia) according to the manufacturer's instructions. Individuals aged 4-82 years, who were candidates for TB infection screening for contact investigation were prospectively recruited. On 196 samples, the QIAreach-QFT showed a positive percent agreement (sensitivity) was 96.5% (CI 87.9-99.6%), a negative percent agreement (specificity) 94.2% (CI 88.4% to 97.6%) and an overall percentage of agreement was 94.9% (95% CI 90.6-97.6%) with a Cohen's κ of 0,88. Out of 196, 5.6% (11/196) samples gave an error result on QIAreach-QFT and 4.1% (8/196) samples gave indeterminate result on QFT-plus. The TTR for QIAreach QFT positive samples varied from 210-1200 seconds (20 min) and significantly correlated with IFN-γ level of QFT-Plus. QIAreach QFT could be considered an accurate and reliable point-of-need test to diagnose TB infection helping to achieve the WHO End TB programme goals even in decentralised settings where laboratory expertise and infrastructure may be limited.
  3. Senin A, Noordin NM, Sani JAM, Mahat D, Donadel M, Scobie HM, et al.
    PLoS One, 2024;19(3):e0298730.
    PMID: 38483868 DOI: 10.1371/journal.pone.0298730
    INTRODUCTION: A lateral flow rapid diagnostic test (RDT) enables detection of measles specific immunoglobulin M (IgM) antibody in serum, capillary blood, and oral fluid with accuracy consistent with enzyme immunoassay (EIA). The objectives of the study were: 1) to assess measles RDT inter-reader agreement between two clinic staff; 2) to assess the sensitivity and specificity of the measles RDT relative to standard surveillance testing in a low transmission setting; 3) to evaluate the knowledge, attitudes, and practices of staff in clinics using the RDT; and 4) to assess the impact of RDT testing on the measles public health response in Malaysia.

    MATERIALS AND METHODS: The clinic-based prospective evaluation included all suspected measles cases captured by routine measles surveillance at 34 purposely selected clinics in 15 health districts in Malaysia between September 2019 and June 2020, following day-long regional trainings on RDT use. Following informed consent, four specimens were collected from each suspected case, including those routinely collected for standard surveillance [serum for EIA and throat swabs for quantitative reverse transcriptase polymerase chain reaction (RT-qPCR)] together with capillary blood and oral fluid tested with RDTs during the study. RDT impact was evaluated by comparing the rapidity of measles public health response between the pre-RDT implementation (December 2018 to August 2019) and RDT implementation periods (September 2019 to June 2020). To assess knowledge, attitudes, and practices of RDT use, staff involved in the public health management of measles at the selected sites were surveyed.

    RESULTS: Among the 436 suspect cases, agreement of direct visual readings of measles RDT devices between two health clinic staff was 99% for capillary blood (k = 0.94) and 97% for oral fluid (k = 0.90) specimens. Of the total, 45 (10%) were positive by measles IgM EIA (n = 44, including five also positive by RT-qPCR) or RT-qPCR only (n = 1), and 38 were positive by RDT (using either capillary blood or oral fluid). Using measles IgM EIA or RT-qPCR as reference, RDT sensitivity using capillary blood was 43% (95% CI: 30%-58%) and specificity was 98% (95% CI: 96%-99%); using oral fluid, sensitivity (26%, 95% CI: 15%-40%) and specificity (97%, 95% CI: 94%-98%) were lower. Nine months after training, RDT knowledge was high among staff involved with the public health management of measles (average quiz score of 80%) and was highest among those who received formal training (88%), followed by those trained during supervisory visits (83%). During the RDT implementation period, the number of days from case confirmation until initiation of public response decreased by about 5 days.

    CONCLUSION: The measles IgM RDT shows >95% inter-reader agreement, high retention of RDT knowledge, and a more rapid public health response. However, despite ≥95% RDT specificity using capillary blood or oral fluid, RDT sensitivity was <45%. Higher-powered studies using highly specific IgM assays and systematic RT-qPCR for case confirmation are needed to establish the role of RDT in measles elimination settings.

  4. Tan AH, Lohmann K, Tay YW, Lim JL, Ahmad-Annuar A, Ramli N, et al.
    Parkinsonism Relat Disord, 2020 10;79:34-39.
    PMID: 32861104 DOI: 10.1016/j.parkreldis.2020.08.015
    BACKGROUND: An improved understanding of the genetic determinants of Parkinson's disease (PD) in underrepresented populations, and better characterization of genotype-phenotype correlations in monogenic PD, are needed. Scarce literature exists regarding the genetic aetiology of PD in Malays, who comprise 200 million individuals in South-East Asia. Phenotypic data regarding PARK-PINK1 are also limited.

    METHODS: A multi-ethnic cohort of PD patients from Malaysia (n = 499, including 185 Malays) were tested using a next-generation sequencing-based PD gene panel. The prevalence and clinico-radiological features of patients with the PINK1 p. Leu347Pro mutation are described. This mutation has previously only been reported in people of Filipino or Chamorro (native Guamanian) ancestry.

    RESULTS: Homozygous p. Leu347Pro mutations were found in five unrelated Malay patients, yielding a prevalence of 6.9% among Malays with PD onset ≤50 years (2.7% of the Malay group overall). This variant was not detected in the homozygous state in 300 Malay controls, but two were heterozygous carriers (0.67%) indicating a relatively high population frequency in keeping with the high frequency of PARK-PINK1 among Malay patients. Interesting clinical features were observed, e.g., differences in the age at PD onset and clinical progression, despite having the same point mutations. Previously unreported brain MRI abnormalities involving the corticospinal tract and hypothalamus, and "loss of the swallow tail" sign, were documented.

    CONCLUSIONS: This report contributes to the very limited literature on PD genetics in the Malay population, and more broadly to the epidemiological, phenotypic and neuroimaging characterization of PARK-PINK1. It also further supports the pathogenicity of the p. Leu347Pro variant.

  5. Nogueira RG, Qureshi MM, Abdalkader M, Martins SO, Yamagami H, Qiu Z, et al.
    Neurology, 2021 Jun 08;96(23):e2824-e2838.
    PMID: 33766997 DOI: 10.1212/WNL.0000000000011885
    OBJECTIVE: To measure the global impact of COVID-19 pandemic on volumes of IV thrombolysis (IVT), IVT transfers, and stroke hospitalizations over 4 months at the height of the pandemic (March 1 to June 30, 2020) compared with 2 control 4-month periods.

    METHODS: We conducted a cross-sectional, observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.

    RESULTS: There were 91,373 stroke admissions in the 4 months immediately before compared to 80,894 admissions during the pandemic months, representing an 11.5% (95% confidence interval [CI] -11.7 to -11.3, p < 0.0001) decline. There were 13,334 IVT therapies in the 4 months preceding compared to 11,570 procedures during the pandemic, representing a 13.2% (95% CI -13.8 to -12.7, p < 0.0001) drop. Interfacility IVT transfers decreased from 1,337 to 1,178, or an 11.9% decrease (95% CI -13.7 to -10.3, p = 0.001). Recovery of stroke hospitalization volume (9.5%, 95% CI 9.2-9.8, p < 0.0001) was noted over the 2 later (May, June) vs the 2 earlier (March, April) pandemic months. There was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was noted in 3.3% (1,722/52,026) of all stroke admissions.

    CONCLUSIONS: The COVID-19 pandemic was associated with a global decline in the volume of stroke hospitalizations, IVT, and interfacility IVT transfers. Primary stroke centers and centers with higher COVID-19 inpatient volumes experienced steeper declines. Recovery of stroke hospitalization was noted in the later pandemic months.

  6. Aziz ZA, Lee YY, Sidek NN, Ngah BA, Looi I, Hanip MR, et al.
    Neurol Res, 2016 May;38(5):406-13.
    PMID: 27142804 DOI: 10.1080/01616412.2016.1178948
    Gender as an independent predictor in stroke has been well documented. However, data on gender differences among first-ever ischemic stroke in developing country are limited. We aim to describe gender effects on clinical characteristics, thrombolysis treatment received, and outcomes of patients with first-ever ischemic stroke.
  7. Ramadan NS, Wessjohann LA, Mocan A, Vodnar DC, El-Sayed NH, El-Toumy SA, et al.
    Molecules, 2020 May 22;25(10).
    PMID: 32455938 DOI: 10.3390/molecules25102423
    Averrhoa carambola L. is a tropical tree with edible fruit that grows at different climatic conditions. Despite its nutritive value and reported health benefits, it is a controversial fruit owing to its rich oxalate content. The present study aimed at investigating aroma and nutrient primary metabolites distribution in A. carambola fruits grown in Indonesia, Malaysia (its endemic origin) versus Egypt, and at different ripening stages. Two techniques were employed to assess volatile and non-volatile metabolites including headspace solid-phase micro-extraction (HS-SPME) joined with gas chromatography coupled with mass-spectrometry (GC-MS) and GC-MS post silylation, respectively. Twenty-four volatiles were detected, with esters amounting for the major class of volatiles in Egyptian fruit at ca. 66%, with methyl caproate as the major component, distinguishing it from other origins. In contrast, aldehydes predominated tropically grown fruits with the ether myristicin found exclusively in these. Primary metabolites profiling led to the identification of 117 metabolites viz. sugars, polyols and organic acids. Fructose (38-48%) and glucose (21-25%) predominated sugar compositions in ripe fruits, whereas sorbitol was the major sugar alcohol (2.4-10.5%) in ripe fruits as well. Oxalic acid, an anti-nutrient with potential health risks, was the major organic acid detected in all the studied fruits (1.7-2.7%), except the Malaysian one (0.07%). It increases upon fruit ripening, including considerable amounts of volatile oxalate esters detected via SPME, and which must not be omitted in total oxalate determinations for safety assessments.
  8. Zainal Abidin N, Noorizhab MNF, Teh LK, Lim WF, Mohd Noordin N, Aziz ZA, et al.
    Microbiol Resour Announc, 2021 Jun 24;10(25):e0035221.
    PMID: 34165334 DOI: 10.1128/MRA.00352-21
    In the battle against tuberculosis (TB), plasticity of the Mycobacterium tuberculosis genome is believed to contribute to the pathogen's virulence and drug resistance. Here, we report 10 draft genome sequences of clinical M. tuberculosis isolated in Malaysia as the basis for understanding the genome plasticity of the M. tuberculosis isolates.
  9. Yap WY, Che Ab Aziz ZA, Azami NH, Al-Haddad AY, Khan AA
    Med Princ Pract, 2017;26(5):464-469.
    PMID: 28934753 DOI: 10.1159/000481623
    OBJECTIVE: To evaluate the push-out bond strength and failure modes of different sealers/obturation systems to intraradicular dentin at 2 weeks and 3 months after obturation compared to AH Plus®/gutta-percha.

    MATERIALS AND METHODS: A total of 180 root slices from 60 single-canal anterior teeth were prepared and assigned to 5 experimental groups (n = 36 in each group), designated as G1 (AH Plus®/gutta-percha), G2 (TotalFill BC™ sealer/BC-coated gutta-percha), G3 (TotalFill BC™ sealer/gutta-percha), G4 (EndoREZ® sealer/EndoREZ®-coated gutta-percha), and G5 (EndoREZ® sealer/gutta-percha). Push-out bond strengths of 18 root slices in each group were assessed at 2 weeks and the other 18 at 3 months after obturation using a universal testing machine. Data were analyzed using repeated measures ANOVA. An independent t test was used to compare the mean push-out bond strength for each group at 2 weeks and 3 months after obturation.

    RESULTS: The mean push-out bond strengths of G4 and G5 were significantly lower than those of G1, G2, and G3 (p < 0.05) at both 2 weeks (G1: 1.46 ± 0.29 MPa, G2: 1.74 ± 0.43 MPa, G3: 1.74 ± 0.43 MPa, G4: 0.66 ± 0.31 MPa, G5: 0.74 ± 0.47 MPa) and 3 months after obturation (G1: 1.70 ± 1.05 MPa, G2: 3.69 ± 1.20 MPa, G3: 2.84 ± 0.83 MPa, G4: 0.14 ± 0.05 MPa, G5: 0.24 ± 0.10 MPa). The mean push-out bond strengths of G2 (3.69 ± 1.20 MPa) and G3 (2.84 ± 0.83 MPa) were higher at 3 months compared to 2 weeks after obturation (G2: 1.74 ± 0.43 MPa, G3: 1.33 ± 0.29 MPa).

    CONCLUSION: The TotalFill BC™ obturation system (G2) and the TotalFill BC™ sealer/gutta-percha (G3) showed comparable bond strength to AH Plus®. Their bond strength increased over time, whereas the EndoREZ® obturation system (G4) and EndoREZ sealer (G5) had low push-out bond strength which decreased over time.

  10. Abu Kasim NH, Govindasamy V, Gnanasegaran N, Musa S, Pradeep PJ, Srijaya TC, et al.
    J Tissue Eng Regen Med, 2015 Dec;9(12):E252-66.
    PMID: 23229816 DOI: 10.1002/term.1663
    The discovery of mesenchymal stem cells (MSCs) from a myriad of tissues has triggered the initiative of establishing tailor-made stem cells for disease-specific therapy. Nevertheless, lack of understanding on the inherent differential propensities of these cells may restrict their clinical outcome. Therefore, a comprehensive study was done to compare the proliferation, differentiation, expression of cell surface markers and gene profiling of stem cells isolated from different sources, viz. bone marrow, Wharton's jelly, adipose tissue and dental pulp. We found that although all MSCs were phenotypically similar to each other, Wharton's jelly (WJ) MSCs and dental pulp stem cells (DPSCs) were highly proliferative as compared to bone marrow (BM) MSCs and adipose tissue (AD) MSCs. Moreover, indistinguishable cell surface characteristics and differentiation capacity were confirmed to be similar among all cell types. Based on gene expression profiling, we postulate that BM-MSCs constitutively expressed genes related to inflammation and immunodulation, whereas genes implicated in tissue development were highly expressed in AD-MSCs. Furthermore, the transcriptome profiling of WJ-MSCs and DPSCs revealed an inherent bias towards the neuro-ectoderm lineage. Based on our findings, we believe that there is no unique master mesenchymal stem cell that is appropriate to treat all target diseases. More precisely, MSCs from different sources exhibit distinct and unique gene expression signatures that make them competent to give rise to specific lineages rather than others. Therefore, stem cells should be subjected to rigorous characterization and utmost vigilance needs to be adopted in order to choose the best cellular source for a particular disease.
  11. Chen XW, Shafei MN, Aziz ZA, Sidek NN, Musa KI
    J Neurol Sci, 2019 Jun 15;401:130-135.
    PMID: 31000206 DOI: 10.1016/j.jns.2019.04.015
    BACKGROUND: Stroke outcomes could be a quality indicator across the continuum of care and inform stroke management policymaking. However, this topic has rarely to date been studied directly.

    AIMS: We sought to investigate recent trends in stroke outcomes at hospital discharge among first-ever stroke patients.

    METHODS: This was an analysis of data from the Malaysia National Stroke Registry. Patients aged 18 years or older documented as having a first episode of stroke in the registry were recruited. Subsequently, the comparison of proportions for overall and sex-specific stroke outcomes between years (from 2009 to 2017) was conducted. The primary outcome was modified Rankin Scale score, which was assessed at hospital discharge, and each patient was categorized as follows: 1) functional independence, 2) functional dependence, or 3) death for analysis.

    RESULTS: This study included 9361 first-ever stroke patients. Approximately 36.2% (3369) were discharged in an independence state, 53.1% (4945) experienced functional dependence, and 10.8% (1006) patients died at the time of hospital discharge. The percentage of patients who were discharged independently increased from 23.3% in 2009 to 46.5% in 2017, while that of patients discharged in a disabled state fell from 56.0% in 2009 to 45.6% in 2017. The percentage of death at discharge was reduced from 20.7% in 2009 to 7.8% in 2017. These findings suggest that the proportions of stroke outcomes at hospital discharge have changed significantly over time (p 

  12. Aziz ZA, Lee YY, Ngah BA, Sidek NN, Looi I, Hanip MR, et al.
    J Stroke Cerebrovasc Dis, 2015 Dec;24(12):2701-9.
    PMID: 26338106 DOI: 10.1016/j.jstrokecerebrovasdis.2015.07.025
    Stroke remains a major health burden worldwide. The incidence and prevalence rates of stroke are decreasing in developed countries, an opposite trend is taking place in the Asia Pacific, where an increasing number of patients are being diagnosed with acute stroke. The results of the present study on acute stroke in multi-ethnic Malaysia will significantly contribute to the global stroke epidemiological data. We aimed to present epidemiological data of stroke including incidence and prevalence rates as well as associated risk factors from a prospective nationwide hospital-based registry from 2010 to 2014.
  13. Albitar O, Harun SN, Abidin NE, Tangiisuran B, Zainal H, Looi I, et al.
    J Stroke Cerebrovasc Dis, 2020 Oct;29(10):105173.
    PMID: 32912507 DOI: 10.1016/j.jstrokecerebrovasdis.2020.105173
    BACKGROUND: Diabetes and obesity are established risk factors for stroke. The current study aimed to assess risk factors of ischemic stroke recurrence in diabetic patients based on their body mass index (BMI).

    METHODS: A total of 4005 diabetic patients who had a history of ischemic stroke were identified in a retrospective cross-sectional dataset from the Malaysian National Neurology Registry. Patients were classified based on BMI, and multivariable regression analysis was used to evaluate the association between risk factors and recurrent ischemic stroke.

    RESULTS: Among obese patients, those with ischemic heart disease (aOR, 1.873; 95% CI, 1.131-3.103), received formal education (aOR, 2.236; 95% CI, 1.306-3.830), and received anti-diabetic medication (aOR, 1.788; 95% CI, 1.180-2.708) had a higher stroke recurrence risk, while receiving angiotensin receptors blockers (aOR, 0.261; 95% CI, 0.126-0.543) lowered the odds of recurrence. Overweight patients with hypertension (aOR, 1.011; 95% CI, 1.002-1.019) for over 10 years (aOR, 3.385; 95% CI, 1.088-10.532) and diabetes prior to the first stroke (aOR, 1.823; 95% CI, 1.020-3.259) as well as those received formal education (aOR, 2.403; 95% CI, 1.126-5.129) had higher odds of stroke recurrence, while receiving angiotensin-converting enzyme inhibitors (aOR, 0.244; 95% CI, 0.111-0.538) lowered the recurrence risk. Normal weight East Malaysians (aOR, 0.351; 95% CI, 0.164-0.750) receiving beta-blockers (aOR, 0.410; 95% CI, 0.174-0.966) had lower odds of stroke recurrence.

    CONCLUSIONS: Ischemic heart disease, hypertension, receiving anti-hypertensive agents, and educational level were independent predictors of recurrent stroke in obese patients. Managing the modifiable risk factors can decrease the odds of stroke recurrence.

  14. Wei LK, Au A, Menon S, Griffiths LR, Kooi CW, Irene L, et al.
    J Stroke Cerebrovasc Dis, 2017 Nov;26(11):2482-2493.
    PMID: 28760411 DOI: 10.1016/j.jstrokecerebrovasdis.2017.05.048
    INTRODUCTION: The association between ischemic stroke and genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR; 677C>T and 1298A>C), endothelial nitric oxide synthase (eNOS; -786T>C, +894G>T, and variable number tandem repeat [VNTR]), phosphodiesterase 4D (PDE4D; SNPs 83 and 87), angiotensin-converting enzyme (ACE) I/D, angiotensinogen (AGT) 235M>T, paraoxonase 1 (PON1) 192Q>R, and apolipoprotein E (ApoE) ε2ε3ε4 remains inconclusive. Therefore, this updated meta-analysis aimed to clarify the presumed influence of genetic polymorphisms on ischemic stroke by meta-analyzing the comprehensive coverage of all individual association studies.

    METHODS: All case-control studies published in different languages such as English, Japanese, Korean, Spanish, Chinese, Hungarian, Ukrainian, or Russian were identified from databases. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated via fixed- and random-effect models. Sensitivity analysis, heterogeneity test, Hardy Weinberg Equilibrium, and Egger's regression analyses were performed in this study.

    RESULTS: A total of 490 case-control studies with 138,592 cases and 159,314 controls were included in this meta-analysis. Pooled ORs from all the genetic models indicated that MTHFR 677TT and 1298CC, eNOS +894TT and VNTR, PDE4D SNP 83, ACE DD, AGT 235TT, PON1 192RR, and ApoE ε4 polymorphisms were increasing the risks of ischemic stroke. Nevertheless, PDE4D SNP 87 and eNOS -786T>C polymorphisms are not associated with ischemic stroke risks.

    CONCLUSIONS: Hence, the evidence from this meta-analysis concluded that MTHFR (677C>T and 1298A>C), eNOS (+894G>T and VNTR), PDE4D SNP 83, ACE I/D, AGT 235M>T, PON1 192Q>R, and ApoE ε2ε3ε4 polymorphisms predispose individuals to ischemic stroke.

  15. Mohamad Azranyi M, Aziz ZA, Ishak D, Mohd Nais NF, Elias ZA, Sulaiman NAF, et al.
    J Med Microbiol, 2024 Feb;73(2).
    PMID: 38380521 DOI: 10.1099/jmm.0.001809
    Introduction. Non-tuberculous Mycobacteria (NTM) is a group of mycobacteria distinct from the Mycobacterium tuberculosis complex. They can cause opportunistic infections, especially in immunocompromised individuals.Gap Statement. Over the last few years, there has been a growing concern regarding the distribution and antimicrobial resistance of NTM in Malaysia. however, a comprehensive study to fully grasp the NTM situation has yet to be conducted.Aim. This study aimed to investigate the species distribution and antimicrobial susceptibility patterns of NTM isolated from clinical samples in Malaysia from 2018 to 2022.Methodology. A retrospective analysis was conducted on NTM isolates obtained from various clinical specimens over a span of five years. The isolates were identified using phenotypic and molecular techniques, and antimicrobial susceptibility profiles for clinically significant isolates were determined using minimum inhibitory concentration.Results. The study revealed a diverse distribution of NTM species in Malaysia, with Mycobacteroides abscessus complex and Mycobacterium avium complex emerging as the most predominant. Furthermore, the antimicrobial susceptibility patterns showed varying degrees of resistance to commonly used antibiotics, highlighting the significance of treatment tailored to susceptibility testing results.Conclusion. This study provides valuable perspective into the epidemiology of NTM in Malaysia. The information gained from this study should prove useful for empirically treating serious NTM infections prior to species identification and the availability of antimicrobial susceptibility testing results.
  16. Mustafa S, Bahar A, Aziz ZA, Suratman S
    J Environ Manage, 2016 Jan 01;165:159-166.
    PMID: 26433356 DOI: 10.1016/j.jenvman.2015.09.026
    Analytical study of the influence of both the pumping well discharge rate and pumping time on contaminant transport and attenuation is significant for hydrological and environmental science applications. This article provides an analytical solution for investigating the influence of both pumping time and travelling time together for one-dimensional contaminant transport in riverbank filtration systems by using the Green's function approach. The basic aim of the model is to understand how the pumping time and pumping rate, which control the travelling time, can affect the contaminant concentration in riverbank filtration systems. Results of analytical solutions are compared with the results obtained using a MODFLOW numerical model. Graphically, it is found that both analytical and numerical solutions have almost the same behaviour. Additionally, the graphs indicate that any increase in the pumping rate or simulation pumping time should increase the contamination in groundwater. The results from the proposed analytical model are well matched with the data collected from a riverbank filtration site in France. After this validation, the model is then applied to the first pilot project of a riverbank filtration system conducted in Malaysia. Sensitivity analysis results highlight the importance of degradation rates of contaminants on groundwater quality, for which higher utilization rates lead to the faster consumption of pollutants.
  17. Govindasamy V, Abdullah AN, Ronald VS, Musa S, Ab Aziz ZA, Zain RB, et al.
    J Endod, 2010 Sep;36(9):1504-15.
    PMID: 20728718 DOI: 10.1016/j.joen.2010.05.006
    Lately, several new stem cell sources and their effective isolation have been reported that claim to have potential for therapeutic applications. However, it is not yet clear which type of stem cell sources are most potent and best for targeted therapy. Lack of understanding of nature of these cells and their lineage-specific propensity might hinder their full potential. Therefore, understanding the gene expression profile that indicates their lineage-specific proclivity is fundamental to the development of successful cell-based therapies.
  18. Al-Haddad AY, Kutty MG, Abu Kasim NH, Che Ab Aziz ZA
    J Dent Sci, 2017 Dec;12(4):340-346.
    PMID: 30895073 DOI: 10.1016/j.jds.2017.03.008
    Background/purpose: Intraradicular moisture is not standardized and alters the sealing properties and adhesion of root sealers. The aim of this work was to evaluate the effect of different moisture on the constitution of bioceramic sealers.

    Materials and methods: The sealers were evaluated before mixing, and after setting using X-ray diffraction (XRD), Energy Dispersive Analysis (EDX) and Scanning Electron Microscope (SEM) techniques. Twenty four extracted teeth were prepared and assigned to four groups according to the moisture conditions: (1) dry: using ethanol as final irrigation, (2) normal: using paper points until the last one appeared dry, (3) moist: using a Luer adapter for 5 s followed by 1 paper point, and (4) wet: the canals remained totally flooded. The roots were filled with MTA Fillapex® and Endosequence® BC and kept in phosphate buffer solution at 37 °C for 10 days. Each root was sectioned transversally and longitudinally. The sealers harvested from longitudinal sections were analysed using XRD. Whilst the transverse sections were analysed using SEM/EDX.

    Results: The XRD analysis showed MTA Fillapex composed of Bismuth trioxide, calcium silicate and tricalcium aluminate. The intensity of peaks in the wet condition was reduced. Endosequence BC contained mainly calcium silicate, calcium silicate hydrate, zirconia and calcium hydroxide. The wet condition showed a small increase in hydrated calcium silicate. The EDX analysis showed changes in the elemental concentrations with different moisture conditions. The surface morphology differed with different moisture conditions.

    Conclusion: Tested sealers have different constitution that not affected by the degree of moisture. However, it changed their relative quantity.

  19. Govindasamy V, Ronald VS, Abdullah AN, Nathan KR, Ab Aziz ZA, Abdullah M, et al.
    J Dent Res, 2011 May;90(5):646-52.
    PMID: 21335539 DOI: 10.1177/0022034510396879
    The post-natal dental pulp tissue contains a population of multipotent mesenchymal progenitor cells known as dental pulp stromal/stem cells (DPSCs), with high proliferative potential for self-renewal. In this investigation, we explored the potential of DPSCs to differentiate into pancreatic cell lineage resembling islet-like cell aggregates (ICAs). We isolated, propagated, and characterized DPSCs and demonstrated that these could be differentiated into adipogenic, chondrogenic, and osteogenic lineage upon exposure to an appropriate cocktail of differentiating agents. Using a three-step protocol reported previously by our group, we succeeded in obtaining ICAs from DPSCs. The identity of ICAs was confirmed as islets by dithiozone-positive staining, as well as by expression of C-peptide, Pdx-1, Pax4, Pax6, Ngn3, and Isl-1. There were several-fold up-regulations of these transcription factors proportional to days of differentiation as compared with undifferentiated DPSCs. Day 10 ICAs released insulin and C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Our results demonstrated for the first time that DPSCs could be differentiated into pancreatic cell lineage and offer an unconventional and non-controversial source of human tissue that could be used for autologous stem cell therapy in diabetes.
  20. Ahmad NA, Naimie Z, Lui JL, Aziz AA, Abdullah M, Abu Kasim NH, et al.
    J Dent Educ, 2012 Oct;76(10):1377-83.
    PMID: 23066138
    This study is part of ongoing educational research conducted by the Department of Conservative Dentistry, University of Malaya, Malaysia, to evaluate the perception of clinical pairing. A thirteen-question survey was distributed to 148 dental students after they had experienced four-handed dentistry. The objectives were to identify the advantages, disadvantages, and the acceptance of the implementation of clinical pairing from the students' point of view. The responses from the open-ended questions were categorized into six main themes (areas of interest): quality-related (Q), patient-related (PT), partner-related (P), lecturer-related (T), infection control (IC), and learning environment (L). Data analysis was done using SPSS version 18. Results indicated that the students perceived they possessed enough knowledge regarding clinical pairing. However, it was found that they still preferred to work independently as compared to working in pairs. The benefits of clinical pairing may not be viewed in the same vein by both dental students and teachers. The quality-related theme was perceived by students as the main advantage of clinical pairing, whilst the partner-related theme was perceived otherwise. The study also revealed that students may have some preconceived notions about pairing that may have impaired their acceptance. As a consequence, some reluctance was seen in their responses.
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links