MyMedR

Displaying all 16 publications

Abstract:

Sort:

Fulltext Performance Evaluation of Localization Accuracy for a Log-Normal Shadow Fading Wireless Sensor Network under Physical Barrier Attacks

Hussein AA, Rahman TA, Leow CY

Sensors (Basel), 2015;15(12):30545-70.
PMID: 26690159 DOI: 10.3390/s151229817

Localization is an apparent aspect of a wireless sensor network, which is the focus of much interesting research. One of the severe conditions that needs to be taken into consideration is localizing a mobile target through a dispersed sensor network in the presence of physical barrier attacks. These attacks confuse the localization process and cause location estimation errors. Range-based methods, like the received signal strength indication (RSSI), face the major influence of this kind of attack. This paper proposes a solution based on a combination of multi-frequency multi-power localization (C-MFMPL) and step function multi-frequency multi-power localization (SF-MFMPL), including the fingerprint matching technique and lateration, to provide a robust and accurate localization technique. In addition, this paper proposes a grid coloring algorithm to detect the signal hole map in the network, which refers to the attack-prone regions, in order to carry out corrective actions. The simulation results show the enhancement and robustness of RSS localization performance in the face of log normal shadow fading effects, besides the presence of physical barrier attacks, through detecting, filtering and eliminating the effect of these attacks.
Fulltext Robust multiple frequency multiple power localization schemes in the presence of multiple jamming attacks

Hussein AA, Leow CY, Rahman TA

PLoS One, 2017;12(5):e0177326.
PMID: 28493977 DOI: 10.1371/journal.pone.0177326

Localization of the wireless sensor network is a vital area acquiring an impressive research concern and called upon to expand more with the rising of its applications. As localization is gaining prominence in wireless sensor network, it is vulnerable to jamming attacks. Jamming attacks disrupt communication opportunity among the sender and receiver and deeply impact the localization process, leading to a huge error of the estimated sensor node position. Therefore, detection and elimination of jamming influence are absolutely indispensable. Range-based techniques especially Received Signal Strength (RSS) is facing severe impact of these attacks. This paper proposes algorithms based on Combination Multiple Frequency Multiple Power Localization (C-MFMPL) and Step Function Multiple Frequency Multiple Power Localization (SF-MFMPL). The algorithms have been tested in the presence of multiple types of jamming attacks including capture and replay, random and constant jammers over a log normal shadow fading propagation model. In order to overcome the impact of random and constant jammers, the proposed method uses two sets of frequencies shared by the implemented anchor nodes to obtain the averaged RSS readings all over the transmitted frequencies successfully. In addition, three stages of filters have been used to cope with the replayed beacons caused by the capture and replay jammers. In this paper the localization performance of the proposed algorithms for the ideal case which is defined by without the existence of the jamming attack are compared with the case of jamming attacks. The main contribution of this paper is to achieve robust localization performance in the presence of multiple jamming attacks under log normal shadow fading environment with a different simulation conditions and scenarios.
Fulltext Enabling Remote Health-Caring Utilizing IoT Concept over LTE-Femtocell Networks

Hindia MN, Rahman TA, Ojukwu H, Hanafi EB, Fattouh A

PLoS One, 2016;11(5):e0155077.
PMID: 27152423 DOI: 10.1371/journal.pone.0155077

As the enterprise of the "Internet of Things" is rapidly gaining widespread acceptance, sensors are being deployed in an unrestrained manner around the world to make efficient use of this new technological evolution. A recent survey has shown that sensor deployments over the past decade have increased significantly and has predicted an upsurge in the future growth rate. In health-care services, for instance, sensors are used as a key technology to enable Internet of Things oriented health-care monitoring systems. In this paper, we have proposed a two-stage fundamental approach to facilitate the implementation of such a system. In the first stage, sensors promptly gather together the particle measurements of an android application. Then, in the second stage, the collected data are sent over a Femto-LTE network following a new scheduling technique. The proposed scheduling strategy is used to send the data according to the application's priority. The efficiency of the proposed technique is demonstrated by comparing it with that of well-known algorithms, namely, proportional fairness and exponential proportional fairness.
Fulltext Statistical Modelling and Characterization of Experimental mm-Wave Indoor Channels for Future 5G Wireless Communication Networks

Al-Samman AM, Rahman TA, Azmi MH, Hindia MN, Khan I, Hanafi E

PLoS One, 2016 Sep 21;11(9):e0163034.
PMID: 27654703 DOI: 10.1371/journal.pone.0163034

This paper presents an experimental characterization of millimeter-wave (mm-wave) channels in the 6.5 GHz, 10.5 GHz, 15 GHz, 19 GHz, 28 GHz and 38 GHz frequency bands in an indoor corridor environment. More than 4,000 power delay profiles were measured across the bands using an omnidirectional transmitter antenna and a highly directional horn receiver antenna for both co- and cross-polarized antenna configurations. This paper develops a new path-loss model to account for the frequency attenuation with distance, which we term the frequency attenuation (FA) path-loss model and introduce a frequency-dependent attenuation factor. The large-scale path loss was characterized based on both new and well-known path-loss models. A general and less complex method is also proposed to estimate the cross-polarization discrimination (XPD) factor of close-in reference distance with the XPD (CIX) and ABG with the XPD (ABGX) path-loss models to avoid the computational complexity of minimum mean square error (MMSE) approach. Moreover, small-scale parameters such as root mean square (RMS) delay spread, mean excess (MN-EX) delay, dispersion factors and maximum excess (MAX-EX) delay parameters were used to characterize the multipath channel dispersion. Multiple statistical distributions for RMS delay spread were also investigated. The results show that our proposed models are simpler and more physically-based than other well-known models. The path-loss exponents for all studied models are smaller than that of the free-space model by values in the range of 0.1 to 1.4 for all measured frequencies. The RMS delay spread values varied between 0.2 ns and 13.8 ns, and the dispersion factor values were less than 1 for all measured frequencies. The exponential and Weibull probability distribution models best fit the RMS delay spread empirical distribution for all of the measured frequencies in all scenarios.
Fulltext Atheroprotective effects of pure tocotrienol supplementation in the treatment of rabbits with experimentally induced early and established atherosclerosis

Rahman TA, Hassim NF, Zulkafli N, Muid S, Kornain NK, Nawawi H

Food Nutr Res, 2016;60:31525.
PMID: 27799085 DOI: 10.3402/fnr.v60.31525

Atherosclerosis is the main cause of coronary artery disease -related deaths worldwide. The atheroprotective properties of pure tocotrienols (T3) in the absence of alpha-tocopherol (α-TCP) in vitamin E has not been extensively examined.
Fulltext Window-Based Channel Impulse Response Prediction for Time-Varying Ultra-Wideband Channels

Al-Samman AM, Azmi MH, Rahman TA, Khan I, Hindia MN, Fattouh A

PLoS One, 2016;11(12):e0164944.
PMID: 27992445 DOI: 10.1371/journal.pone.0164944

This work proposes channel impulse response (CIR) prediction for time-varying ultra-wideband (UWB) channels by exploiting the fast movement of channel taps within delay bins. Considering the sparsity of UWB channels, we introduce a window-based CIR (WB-CIR) to approximate the high temporal resolutions of UWB channels. A recursive least square (RLS) algorithm is adopted to predict the time evolution of the WB-CIR. For predicting the future WB-CIR tap of window wk, three RLS filter coefficients are computed from the observed WB-CIRs of the left wk-1, the current wk and the right wk+1 windows. The filter coefficient with the lowest RLS error is used to predict the future WB-CIR tap. To evaluate our proposed prediction method, UWB CIRs are collected through measurement campaigns in outdoor environments considering line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Under similar computational complexity, our proposed method provides an improvement in prediction errors of approximately 80% for LOS and 63% for NLOS scenarios compared with a conventional method.
Fulltext In vitro study of Nigella sativa and thymoquinone activity on endothelial activation and monocyte adhesion

Yuhainis Firus Khan A, Mohtar F, Rahman TA, Muid SA, Froemming GRA, Nawawi H

J Appl Biomed, 2023 Jun;21(2):73-79.
PMID: 37212154 DOI: 10.32725/jab.2023.006

INTRODUCTION: Thymoquinone (TQ) is one of the bioactive compounds in Nigella sativa (NS). Also known as black seeds/cumin, it has been postulated to possess anti-atherogenic properties. However, research on the effects of NS oil (NSO) and TQ on atherogenesis remain scarce. The aim of this study is to determine gene and protein expression of Intercellular Adhesion Molecule-1 (ICAM-1), Vascular Cell Adhesion Molecule-1 (VCAM-1), and Endothelial-eukocyte adhesion molecule (E-selectin) in Human Coronary Artery Endothelial Cells (HCAECs).
METHODS: HCAECs were stimulated for 24 hours (h) with 200 µg/ml of Lipopolysaccharides (LPS) and different concentrations of NSO (55, 110, 220, 440 µg/ml) or TQ (4.5, 9.0, 18.0, 36.0 µm). The effects of NSO and TQ on gene and protein expressions were measured using multiplex gene assay and ELISA assay, respectively. Rose Bengal assay was used to analyse monocyte binding activity.
RESULTS: NSO and TQ significantly reduced ICAM-1 and VCAM-1 gene and protein expressions. TQ showed significant reduction activity of the biomarkers in dose dependent manner. HCAECs pre-treated with NSO and TQ for 24 h significantly lowered monocytes adherence compared to non-treated HCAECs.
CONCLUSIONS: NSO and TQ supplementation have anti-atherogenic properties and inhibit monocytes' adherence to HCAECs via down-regulation of ICAM-1 expression. NSO could potentially be incorporated in standard treatment regimens to prevent atherosclerosis and its related complications.
Unheard voices of global surgery - trauma services in sub-Saharan Africa: a correspondence

Mehta A, Wireko AA, Ohenewaa Tenkorang P, Ng JC, Rahman TA, Sikora V, et al.

Int J Surg, 2023 Mar 01;109(3):521-522.
PMID: 36906789 DOI: 10.1097/JS9.0000000000000145
Effects of Dapagliflozin on Endothelial Dysfunction in Type 2 Diabetes With Established Ischemic Heart Disease (EDIFIED)

Zainordin NA, Hatta SFWM, Mohamed Shah FZ, Rahman TA, Ismail N, Ismail Z, et al.

J Endocr Soc, 2020 Jan 01;4(1):bvz017.
PMID: 31993550 DOI: 10.1210/jendso/bvz017

Objectives: To evaluate the effect of the sodium-glucose cotransporter 2 inhibitor (SGLT2-I) dapagliflozin on endothelial function in patients with high-risk type 2 diabetes mellitus (T2DM).
Methods: This was a prospective, double-blind, randomized, placebo-controlled, clinical trial of patients with T2DM with underlying ischemic heart disease who were receiving metformin and insulin therapy (n = 81). After 12-weeks of additional therapy with either dapagliflozin (n = 40) or placebo (n = 41), systemic endothelial function was evaluated by change in flow-mediated dilation (ΔFMD), change in nitroglycerin-mediated dilation (ΔNMD) and surrogate markers including intercellular adhesion molecule 1 (ICAM-1), endothelial nitric oxide synthase (eNOS), high-sensitivity C-reactive protein (hs-CRP), and lipoprotein(a) (Lp[a]). Glycemic and lipid profiles were also measured.
Results: The dapagliflozin group demonstrated significant reductions of hemoglobin A1c (HbA1c) and fasting blood glucose (FBG) compared to the placebo group (ΔHbA1c -0.83 ± 1.47% vs -0.16 ± 1.25%, P = 0.042 and ΔFBG vs -0.73 ± 4.55 mmol/L vs -1.90 ± 4.40 mmol/L, P = 0.015, respectively). The placebo group showed worsening of ΔFMD while the dapagliflozin group maintained similar measurements pre- and posttherapy (P = not significant). There was a reduction in ICAM-1 levels in the dapagliflozin group (-83.9 ± 205.9 ng/mL, P < 0.02), which remained unchanged in the placebo group (-11.0 ± 169.1 ng/mL, P = 0.699). Univariate correlation analysis revealed a significant negative correlation between HbA1c and ΔFMD within the active group.
Conclusion: A 12-week therapy with dapagliflozin, in addition to insulin and metformin therapies, in high-risk patients resulted in significant reductions in HbA1c, FBG, and surrogate markers of the endothelial function. Although the dapagliflozin group demonstrated a significant association between reduction in HbA1c and improvement in FMD, there was no significant difference in FMD between the 2 groups.
Serum lipoprotein(a) concentrations amongst the native ethnic communities in Malaysia

Chua YA, Ismail Z, Rahmat R, Kasim NAM, Rahman TA, Ramli AS, et al.

Atherosclerosis, 2017 Aug;263:e209.
PMID: 29365811 DOI: 10.1016/j.atherosclerosis.2017.06.677
Expression quantitative trait loci (eQTL): from population genetics to precision medicine

Wong ZQ, Deng L, Cengnata A, Rahman TA, Ismail A, Hong Lim RL, et al.

J Genet Genomics, 2025 Feb 20.
PMID: 39986349 DOI: 10.1016/j.jgg.2025.02.003

Evidence has shown that differential transcriptomic profiles among human populations from diverse ancestries, supporting the role of genetic architecture in regulating gene expression alongside environmental stimuli. Genetic variants that regulate gene expression, known as expression quantitative trait loci (eQTL), are primarily shaped by human migration history and evolutionary forces, likewise, regulation of gene expression in principle could have been influenced by these events. Therefore, a comprehensive understanding of how human evolution impacts eQTL offers important insights into how phenotypic diversity is shaped. Recent studies, however, suggest that eQTL is enriched in genes that are selectively constrained. Whether eQTL is minimally affected by selective pressures remains an open question and requires comprehensive investigations. In addition, such studies are primarily dominated by the major populations of European ancestry, leaving many marginalized populations underrepresented. These observations indicate there exists a fundamental knowledge gap in the role of genomics variation on phenotypic diversity, which potentially hinders precision medicine. This article aims to revisit the abundance of eQTL across diverse populations and provide an overview of their impact from the population and evolutionary genetics perspective, subsequently discuss their influence on phenomics, as well as challenges and opportunities in the applications to precision medicine.
Fulltext Diagnostic performance of various familial hypercholesterolaemia diagnostic criteria compared to Dutch lipid clinic criteria in an Asian population

Abdul-Razak S, Rahmat R, Mohd Kasim A, Rahman TA, Muid S, Nasir NM, et al.

BMC Cardiovasc Disord, 2017 Oct 16;17(1):264.
PMID: 29037163 DOI: 10.1186/s12872-017-0694-z

BACKGROUND: Familial hypercholesterolaemia (FH) is a genetic disorder with a high risk of developing premature coronary artery disease that should be diagnosed as early as possible. Several clinical diagnostic criteria for FH are available, with the Dutch Lipid Clinic Criteria (DLCC) being widely used. Information regarding diagnostic performances of the other criteria against the DLCC is scarce. We aimed to examine the diagnostic performance of the Simon-Broom (SB) Register criteria, the US Make Early Diagnosis to Prevent Early Deaths (US MEDPED) and the Japanese FH Management Criteria (JFHMC) compared to the DLCC.
METHODS: Seven hundered fifty five individuals from specialist clinics and community health screenings with LDL-c level ≥ 4.0 mmol/L were selected and diagnosed as FH using the DLCC, the SB Register criteria, the US MEDPED and the JFHMC. The sensitivity, specificity, efficiency, positive and negative predictive values of individuals screened with the SB register criteria, US MEDPED and JFHMC were assessed against the DLCC.
RESULTS: We found the SB register criteria identified more individuals with FH compared to the US MEDPED and the JFHMC (212 vs. 105 vs. 195; p
Fulltext Genetic Connections and Convergent Evolution of Tropical Indigenous Peoples in Asia

Deng L, Pan Y, Wang Y, Chen H, Yuan K, Chen S, et al.

Mol Biol Evol, 2022 Feb 03;39(2).
PMID: 34940850 DOI: 10.1093/molbev/msab361

Tropical indigenous peoples in Asia (TIA) attract much attention for their unique appearance, whereas their genetic history and adaptive evolution remain mysteries. We conducted a comprehensive study to characterize the genetic distinction and connection of broad geographical TIAs. Despite the diverse genetic makeup and large interarea genetic differentiation between the TIA groups, we identified a basal Asian ancestry (bASN) specifically shared by these populations. The bASN ancestry was relatively enriched in ancient Asian human genomes dated as early as ∼50,000 years before the present and diminished in more recent history. Notably, the bASN ancestry is unlikely to be derived from archaic hominins. Instead, we suggest it may be better modeled as a survived lineage of the initial peopling of Asia. Shared adaptations inherited from the ancient Asian ancestry were detected among the TIA groups (e.g., LIMS1 for hair morphology, and COL24A1 for bone formation), and they are enriched in neurological functions either at an identical locus (e.g., NKAIN3), or different loci in an identical gene (e.g., TENM4). The bASN ancestry could also have formed the substrate of the genetic architecture of the dark pigmentation observed in the TIA peoples. We hypothesize that phenotypic convergence of the dark pigmentation in TIAs could have resulted from parallel (e.g., DDB1/DAK) or genetic convergence driven by admixture (e.g., MTHFD1 and RAD18), new mutations (e.g., STK11), or notably purifying selection (e.g., MC1R). Our results provide new insights into the initial peopling of Asia and an advanced understanding of the phenotypic convergence of the TIA peoples.
Fulltext Relationships between severity of steatosis with glycemic control and carotid intima-media thickness among diabetic patients with ischemic heart disease

Omar N, Koshy M, Hanafiah M, Hatta SFWM, Shah FZM, Johari B, et al.

J Res Med Sci, 2020;25:64.
PMID: 33088301 DOI: 10.4103/jrms.JRMS_560_17

Background: Nonalcoholic fatty liver disease (NAFLD) has become one of the major diseases plaguing worldwide. Several studies reported its association with ischemic heart disease (IHD). This study aims to determine the relationships between severity of steatosis with glycemic control and carotid intima-media thickness (CIMT) among a high-risk population of type 2 diabetes mellitus (T2DM) with proven IHD.
Materials and Methods: This was a cross-sectional study involving patients aged between 18 and 65 years diagnosed with T2DM with IHD (n = 150). Ultrasonography of the abdomen to determine NAFLD severity category and CIMT measurements was performed by two independent radiologists. NAFLD was graded according to the severity of steatosis (NAFLD-3, NAFLD-2, NAFLD-1, and NAFLD-0). Comparison between different stages of NAFLD (NAFLD-3, NAFLD-2, NAFLD-1, and NAFLD-0) was analyzed using Chi-square and analysis of variance tests for categorical and continuous variables, respectively.
Results: The prevalence of NAFLD was 71% (n = 107). NAFLD-1 was detected in 39% of the patients, 32% had NAFLD-2, no patients with NAFLD-3, and 29% had non-NAFLD. There were no patients with NAFLD-2 having higher systolic and diastolic blood pressure, weight, body mass index, waist circumference, total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Glycated hemoglobin (HbA1c) concentration was highest within the NAFLD-2. NAFLD-2 showed higher mean CIMT. Every 1% rise in HbA1c for patients with NAFLD significantly increases the CIMT by 0.03 mm (95% CI: 0.009, 0.052, P = 0.006).
Conclusion: These findings suggest additional atherosclerotic risks within the NAFLD-2 group with significantly higher HbA1c and CIMT compared to the NAFLD-1 and NAFLD-0 groups. It is, therefore, vital to incorporate stricter glycemic control among patients with T2DM and IHD with moderate NAFLD as part of atherosclerotic risk management strategy.
Differential positive selection of malaria resistance genes in three indigenous populations of Peninsular Malaysia

Liu X, Yunus Y, Lu D, Aghakhanian F, Saw WY, Deng L, et al.

Hum Genet, 2015 Apr;134(4):375-92.
PMID: 25634076 DOI: 10.1007/s00439-014-1525-2

The indigenous populations from Peninsular Malaysia, locally known as Orang Asli, continue to adopt an agro-subsistence nomadic lifestyle, residing primarily within natural jungle habitats. Leading a hunter-gatherer lifestyle in a tropical jungle environment, the Orang Asli are routinely exposed to malaria. Here we surveyed the genetic architecture of individuals from four Orang Asli tribes with high-density genotyping across more than 2.5 million polymorphisms. These tribes reside in different geographical locations in Peninsular Malaysia and belong to three main ethno-linguistic groups, where there is minimal interaction between the tribes. We first dissect the genetic diversity and admixture between the tribes and with neighboring urban populations. Later, by implementing five metrics, we investigated the genome-wide signatures for positive natural selection of these Orang Asli, respectively. Finally, we searched for evidence of genomic adaptation to the pressure of malaria infection. We observed that different evolutionary responses might have emerged in the different Orang Asli communities to mitigate malaria infection.
Systematic characterization and comparison of the CYP2C9 variability of the Orang Asli in Malaysia with 12 populations

Teh LK, Subramaniam V, Tuan Abdu Aziz TA, Lee LS, Ismail MI, Yu CY, et al.

Drug Metab. Pharmacokinet., 2016 Aug;31(4):304-13.
PMID: 27325019 DOI: 10.1016/j.dmpk.2016.04.004

We conducted a systematic characterization of CYP2C9 variants in 61 Orang Asli and 96 Singaporean Malays using the whole genome sequences data and compared the variants with the other 11 HapMap populations. The frequency of rs1057910 (CYP2C9*3) is the highest in the Orang Asli compared to other populations. Three alleles with clinical implication were detected in the Orang Asli while 2 were found in the Singaporean Malays. Large numbers of the Orang Asli are predicted to have reduced metabolic capacity and therefore they would require a lower dose of drugs which are metabolized by CYP2C9. They are also at increased risks of adverse effects and therapeutic failures. A large number of CYP2C9 variants in the Orang Asli were not in the Hardy Weinberg Equilibrium which could be due to small sample size or mutations that disrupt the equilibrium of allele frequencies. In conclusion, different polymorphism patterns, allele frequencies, genotype frequencies and LD blocks are observed between the Orang Asli, the Singaporean Malays and the other populations. The study provided new information on the genetic polymorphism of CYP2C9 which is important for the implementation of precision medicine for the Orang Asli.

Filters

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

External Links