Displaying publications 1 - 20 of 75 in total

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  1. Hamid, H., Ngu, P.A.H., Alipiah, F.M.
    MyJurnal
    The issue of classifying objects into groups when measured variables in an experiment are mixed has attracted the attention of statisticians. The Smoothed Location Model (SLM) appears to be a popular classification method to handle data containing both continuous and binary variables simultaneously. However, SLM is infeasible for a large number of binary variables due to the occurrence of numerous empty cells. Therefore, this study aims to construct new SLMs by integrating SLM with two variable extraction techniques, Principal Component Analysis (PCA) and two types of Multiple Correspondence Analysis (MCA) in order to reduce the large number of mixed variables, primarily the binary ones. The performance of the newly constructed models, namely the SLM+PCA+Indicator MCA and SLM+PCA+Burt MCA are examined based on misclassification rate. Results from simulation studies for a sample size of n=60 show that the SLM+PCA+Indicator MCA model provides perfect classification when the sizes of binary variables (b) are 5 and 10. For b=20, the SLM+PCA+Indicator MCA model produces misclassification rates of 0.3833, 0.6667 and 0.3221 for n=60, n=120 and n=180, respectively. Meanwhile, the SLM+PCA+Burt MCA model provides a perfect classification when the sizes of the binary variables are 5, 10, 15 and 20 and yields a small misclassification rate as 0.0167 when b=25. Investigations into real dataset demonstrate that both of the newly constructed models yield low misclassification rates with 0.3066 and 0.2336 respectively, in which the SLM+PCA+Burt MCA model performed the best among all the classification methods compared. The findings reveal that the two new models of SLM integrated with two variable extraction techniques can be good alternative methods for classification purposes in handling mixed variable problems, mainly when dealing with large binary variables.
  2. Khattak, M. A., Arif, A., Hannan, A., Syukri, F., Hamid, H.
    MyJurnal
    Malaysia is currently planning on building its first nuclear power plant to add on more
    variety of national energy mix. This paper is on the study on the feasibility of the plan. We will show
    the current and forecast energy demand that make the nuclear power plant as the major solution to
    cover the deficit. Malaysia current strategy and action on building the plant will be presented in this
    paper. The challenge on delivering this project of energy mix is also a major aspect that will be
    discussed. The international and national policy regarding of nuclear power and its waste has provide
    a rough guidelines to execute this planning. While existing literature points to a correlation between
    nuclear power, strong state involvement, centralized energy planning and the rhetoric linking energy
    to national prestige and security, we show that these factors are not sufficient for a successful nuclear
    program. Another motivation on pursuing nuclear power is to reduce the carbon emission to the
    environment. By the end of this paper, we include the nuclear conventions that Malaysia involve and
    future prospect for nuclear power plant development. Copyright © 2016 Penerbit Akademia Baru -
    All rights reserved.
  3. Qader AQ, Abdul Hamid H
    Radiol Case Rep, 2021 Jul;16(7):1907-1911.
    PMID: 34093935 DOI: 10.1016/j.radcr.2021.04.059
    Gastric volvulus is an uncommon disorder with an unknown incidence, unless it stays in the back of the diagnostician's mind, diagnosis of gastric volvulus, which can have significant morbidity and mortality associated with it, can be easily missed and can present either in the acute or chronic setting with variable symptoms. When it occurs in the acute scenario, patients present with severe epigastric pain and retching without vomiting. Together with inability to pass nasogastric tube, they constitute Borchardt's triad. The presence of a hiatal hernia with persistent vomiting despite initial antiemetic treatment should trigger one to think of gastric volvulus, despite the patient appearing very stable. We report a case which presented in our hospital with abdominal pain and vomiting. As Oesophagogastroduodenoscopy shows hiatal hernia and peptic ulcer. Primary gastric volvulus occurs in the absence of any defect in the diaphragm or adjacent organ pathology and may be caused by weakening of gastric supports. As conclusion; Gastric volvulus is a surgical case, requiring early diagnosis and aggressive management, as a delay results into complications like gangrene and perforation which substantially increase the morbidity and mortality in these patients, and contrast enhanced computed tomography (CECT) is the best modality for diagnosis of gastric volvulus.
  4. Abdul-Hamid H, Mencuccini M
    Tree Physiol, 2009 Jan;29(1):27-38.
    PMID: 19203930 DOI: 10.1093/treephys/tpn001
    Forest growth is an important factor both economically and ecologically, and it follows a predictable trend with age. Generally, growth accelerates as canopies develop in young forests and declines substantially soon after maximum leaf area is attained. The causes of this decline are multiple and may be linked to age- or size-related processes, or both. Our objective was to determine the relative effects of tree age and tree size on the physiological attributes of two broadleaf species. As age and size are normally coupled during growth, an approach based on grafting techniques to separate the effects of size from those of age was adopted. Genetically identical grafted seedlings were produced from scions taken from trees of four age classes, ranging from 4 to 162 years. We found that leaf-level net photosynthetic rate per unit of leaf mass and some other leaf structural and biochemical characteristics had decreased substantially with increasing size of the donor trees in the field, whereas other gas exchange parameters expressed on a leaf area basis did not. In contrast, these parameters remained almost constant in grafted seedlings, i.e., scions taken from donor trees with different meristematic ages show no age-related trend after they were grafted onto young rootstocks. In general, the results suggested that size-related limitations triggered the declines in photosynthate production and tree growth, whereas less evidence was found to support a role of meristematic age.
  5. Wong SL, Abdul Hamid H
    Malays J Med Sci, 2010 Apr;17(2):4-9.
    PMID: 22135531
    This study observed the widest ureteric diameter in negative intravenous urogram (IVU) examinations using low osmolar contrast media.
  6. Abdul Karim AK, Ahmad MF, Abdul Hamid H
    Med J Malaysia, 2021 05;76(3):417-418.
    PMID: 34031343
    Fertility preservation is significant for oncology patients to maintain their ability to start a family when they are ready. Onco-fertility, as a discipline, exists at the intersection of oncology and reproductive medicine that safeguards and expands the fertility options for cancer survivors, by facilitating early intervention and suitable treatment with favourable outcomes. Successful fertility preservation requires a comprehensive networking among the gynaecologists, oncologists, pathologists, imaging and other specialists, involved in diagnosing and treating cancer in the reproductive age group. There are several ways in which fertility can be preserved, like role of gonadotrophin releasing hormone analogues, in vitro maturation, and cryopreservation.
  7. Hassan K, Vijayasilan T, Mahmood Z, Abdul Hamid H, Chin YM
    Singapore Med J, 1988 Oct;29(5):462-8.
    PMID: 3241975
    Whole blood samples from patients with various forms of alpha- and beta- thalassaemia were incubated with 14C-Leucine to determine the relative rates of production of the alpha and beta chains by their reticulocytes. The labelled globin chains were fractionated by CM-Cellulose Chromatography in 8M Urea and the incorporated activity determined. The relative rates of synthesis of alpha and beta chains in some cases of alpha and beta- thalassaemia were established and the chain synthetic ratios were compared with similar ratios in normal individuals. The results show that it is possible to identify from the relative rates of in-vitro synthesis of the alpha and beta chains, the presence of the common thalassaemia slates in particular beta-thal trait, beta-thal homozygotes, Hb H disease and alpha0-thal trait. The presence of transfused blood does not affect the result. This study indicates that an abnormal alpha/beta chain synthesis ratio is useful in defining alpha and beta-thalassaemia variants.
  8. Abdul-Hamid H, Kai J, Anis Safura R
    Ann Fam Med, 2023 Jan 01.
    PMID: 37037012 DOI: 10.1370/afm.21.s1.4220
    Context Familial hypercholesterolaemia (FH) is a common autosomal dominant disorder, causing elevated cholesterol from birth, premature heart disease, and early death. Objective This study explored primary care physicians' experiences and perspectives on identifying FH in Malaysian primary care. Study Design and Analysis A qualitative study involving semi-structured interviews and focus group discussions with 22 primary care physicians (PCPs) in two primary care clinic settings. The interviews and focus group discussions were audio recorded, and the recordings were transcribed verbatim. The data in the transcripts were analysed using thematic approach. Setting Primary Care Clinics Population Studied Primary Care Physicians in two primary care clinics. Intervention A qualitative study involving semi-structured interviews and focus group discussions Outcome Measures Primary Care Physicians' perceptions and experiences of identifying individuals at high risk of FH in their clinical practice, and the acceptability and perceived challenges of trying to do this were explored during the interviews and focus group discussions. Findings PCPs felt there was potential for FH to be identified earlier in primary care. They had some existing knowledge and awareness of diagnostic criteria for FH but highlighted several challenges. In their practice, this included limited time in routine clinical care, availability of medication and clinical expertise; and critical lack of family history and physical examination findings in health records. The barriers on a systemic level were shortage of lipid specialist services and the absence of local care pathways for FH. The PCPs recommended a user-friendly case-finding tool for FH, and establishing FH registry and clinical practice guideline in Malaysia, alongside a national FH screening strategy and awareness campaigns for both clinicians and general public. Conclusions PCPs are positive about improving the identification of FH in primary care. However greater support in their practice and wider system developments and change are needed.
  9. Yusoff M, Hamid H, Houghton P
    Molecules, 2014 Jan 20;19(1):1201-11.
    PMID: 24448061 DOI: 10.3390/molecules19011201
    Quaternary alkaloids are the major alkaloids isolated from Tinospora species. A previous study pointed to the necessary presence of quaternary nitrogens for strong acetylcholinesterase (AChE) inhibitory activity in such alkaloids. Repeated column chromatography of the vine of Tinospora crispa extract led to the isolation of one new protoberberine alkaloid, 4,13-dihydroxy-2,8,9-trimethoxydibenzo[a,g]quinolizinium (1), along with six known alkaloids-dihydrodiscretamine (2), columbamine (3), magnoflorine (4), N-formylannonaine (5), N-formylnornuciferine (6), and N-trans-feruloyltyramine (7). The seven compounds were isolated and structurally elucidated by spectroscopic analysis. Two known alkaloids, namely, dihydrodiscretamine and columbamine are reported for the first time for this plant. The compounds were tested for AChE inhibitory activity using Ellman's method. In the AChE inhibition assay, only columbamine (3) showed strong activity with IC50 48.1 µM. The structure-activity relationships derived from these results suggest that the quaternary nitrogen in the skeleton has some effect, but that a high degree of methoxylation is more important for acetylcholinesterase inhibition.
  10. Zheng T, Mencuccini M, Abdul-Hamid H
    Physiol Plant, 2023;175(3):e13915.
    PMID: 37087558 DOI: 10.1111/ppl.13915
    Although a substantial body of evidence suggests that large and old trees have reduced metabolic levels, the search for the causes behind this observation has proved elusive. The strong coupling between age and size, commonly encountered in the field, precludes the isolation of the potential causes. We used standard propagation techniques (grafting and air-layering) to decouple the effects of size from those of age in affecting leaf structure, biochemistry and physiology of two broadleaved trees, Acer pseudoplatanus (a diffuse-porous species) and Fraxinus excelsior (a ring-porous species). The first year after establishment of the propagated plants, some of the measurements suggested the presence of age-related declines in metabolism, while other measurements either did not show any difference or suggested variability across treatments not associated with either age or size. During the second year after establishment, only one of the measured properties (specific leaf area) continued to show some evidence of an age-mediated decline (although much reduced compared to the field), whereas, for some properties (particularly for F. excelsior), even the opposite trend of age-related increases was apparent. We concluded that (1) our plants suffered from grafting shock during year 1 and they gradually recovered during year 2; (2) the results over 2 years do not support the statement that age directly mediates ageing in either species but instead suggest that size directly mediates ageing processes; and (3) neither shoots nor roots of A. pseudoplatanus showed any evidence of senescence.
  11. Nguyen D, Yaacob Y, Hamid H, Muda S
    Malays J Med Sci, 2013 Oct;20(5):70-8.
    PMID: 24643401
    Lemierre's syndrome (LS) is a rare life-threatening infective condition typically starting with an oropharyngeal infection causing thrombophlebitis and metastatic abscesses. The most common aetiology of LS is Fusobacterium necrophorum; however, it can also occur after infection with other organisms. LS mainly affects young healthy adults. The initial infection site can be in the head and neck or in the abdomen. The morbidity rate of this disease is high despite aggressive treatments. In this article, we report a 63-year-old male patient with uncontrolled diabetes mellitus, presenting with Klebsiella pneumoniae infection-induced necrotizing fasciitis on the right side of the neck, leading to LS.
  12. Davoodi SR, Hamid H, Arintono S, Muniandy R, Faezi SF
    Traffic Inj Prev, 2011 Apr;12(2):174-9.
    PMID: 21469025 DOI: 10.1080/15389588.2010.533314
    The purpose of this study was to determine the baseline motorcycle riders' perception-response times (PRTs) in an expected object braking task and to determine the significant difference between PRTs of older and younger riders.
  13. Abd Hamid H, Umar NA, Othman H, Das S
    Arch Med Sci, 2010 Dec;6(6):987-90.
    PMID: 22427779 DOI: 10.5114/aoms.2010.19315
    Hyperosmolar hyperglycaemic state (HHS) is a medical emergency which needs immediate medical intervention. A 37-year-old Chinese woman with a history of hypertension attended the Emergency Department. She had a two-day history of involuntary movement, i.e. chorea of the upper limbs, preceded by a one-week history of upper respiratory tract infection. She also had polyuria and polydipsia, although she was never diagnosed as diabetic. The main aim of reporting the present case was to highlight the importance of biochemical investigations involved in the diagnosis of involuntary movements.
    Study site: emergency department, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM)
  14. Binti Abdul Hamid H, Szatkowski L, Budge H, Ojha S
    Pediatr Res, 2021 Oct 29.
    PMID: 34716422 DOI: 10.1038/s41390-021-01821-y
    BACKGROUND: Current recommendations do not support the use of anti-reflux medications to treat gastro-oesophageal reflux disease (GORD) among preterm infants.

    OBJECTIVE: To describe the prevalence of GORD and the use of anti-reflux medications amongst very preterm infants (<32 weeks' gestational age (GA)) in neonatal units in England and Wales.

    DESIGN: Retrospective cohort study using the National Neonatal Research Database.

    RESULTS: Among 58,108 infants [median GA (IQR) 29 (27-30) weeks], 15.8% (n = 9191) had a diagnosis of GORD and 36.9% (n = 12,446) received anti-reflux medications. Those who received anti-reflux medications were more preterm [GA, median (IQR): medications, 28 (26-30) vs. no medications, 30 (28-31); p 

  15. Abdul Hamid H, Szatkowski L, Budge H, Cheah FC, Ojha S
    BMJ Paediatr Open, 2021;5(1):e001153.
    PMID: 34514178 DOI: 10.1136/bmjpo-2021-001153
    Objective: To explore differences in nutritional practices and growth outcomes among preterm infants in neonatal units in Malaysia and the UK.

    Design: Prospective exploratory study of infants born at <34 weeks gestational age (GA).

    Setting: Two neonatal units, one in Malaysia and one in the UK (May 2019 to March 2020).

    Methods: Data collected from birth until discharge and compared between units.

    Results: From 100 infants included, median GA (IQR) was 31 (30-33) and mean±SD birth weight was 1549±444 g. There were more small-for-gestational age infants in Malaysian unit: 12/50 (24%) vs UK: 3/50 (6%), p=0.012 and more morbidities. More Malaysian infants received breast milk (Malaysia: 49 (98%) vs UK: 38 (76%), p=0.001), fortified breast milk (Malaysia: 43 (86%) vs UK: 13 (26%), p<0.001) and exclusive breast milk at discharge (Malaysia: 26 (52%) vs UK: 16 (32%), p=0.043). There was higher parenteral nutrition use among Malaysian infants (40/50 (80%)) vs UK (19/50 (38%)) (p<0.001) with higher protein intake (mean±SD Malaysia: 3.0±0.5 vs UK: 2.7±0.6 g/kg/d, p=0.004) in weeks 1-4 and smaller cumulative protein deficits (mean±SD Malaysia: 11.4±6.1 vs UK: 15.4±8.0 g/kg, p=0.006). There were no significant differences in short-term growth between units and more than half of the infants in both units had ≥1.28 changes in weight-for-age Z-score at discharge (p=0.841).

    Conclusions: An exploratory comparison of practices showed differences in patient characteristics and nutritional practices which impacted growth. Future studies with larger sample sizes and detailed analysis of maternal characteristics and infants' outcomes are needed for improving care of preterm infants in all settings.

  16. Zolkiffly SZI, Stanslas J, Abdul Hamid H, Mehat MZ
    J Ethnopharmacol, 2021 Oct 28;279:114309.
    PMID: 34119609 DOI: 10.1016/j.jep.2021.114309
    ETHNOPHARMACOLOGICAL RELEVANCE: Ficus deltoidea Jack (FD) is widely consumed in traditional medicine as a treatment for various diseases in Malaysia. Each part of the plant such as its leave, stem, fruit and root are used traditionally to treat different types of diseases. Vitexin and isovitexin are bioactive compounds abundantly found in the leaves of FD that possessed many pharmacological properties including neuroprotection. Nonetheless, its effects on key events in neuroinflammation are unknown.

    AIM OF THE STUDY: To determine the inhibitory properties of FD aqueous extract on pro-inflammatory mediators involved in lipopolysaccharide (LPS)-induced microglial cells.

    METHODS: Vitexin and isovitexin in the extract were quantified via high performance liquid chromatography (HPLC). The extract was evaluated for its cytotoxicity activity via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Pre-treatment with the extract on LPS-induced microglial cells was done to determine its antioxidant and anti-neuroinflammatory properties by measuring the level of reactive oxygen species (ROS), nitric oxide (NO), tumour necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) via 2'-7'-dichlorofluorescin diacetate (DCFDA) assay, Griess assay and Western blot respectively.

    RESULTS: The extract at all tested concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL, 100 μg/mL) were not cytotoxic as the percentage viability of microglial cells were all above ~80%. At the highest concentration (100 μg/mL), the extract significantly reduced the formation of ROS, NO, TNF-α, IL-1β and IL-6 in microglial cells induced by LPS.

    CONCLUSION: The extract showed neuroprotective effects by attenuating the levels of pro-inflammatory and cytotoxic factors in LPS-induced microglial cells, possibly by mediating the nuclear factor-kappa B (NF-κB) signalling pathway.

  17. Ibrahim MKA, Hamid H, Law TH, Wong SV
    Accid Anal Prev, 2018 Feb;111:63-70.
    PMID: 29172046 DOI: 10.1016/j.aap.2017.10.023
    Construction of exclusive motorcycle lanes is one of the measures to reduce motorcycle fatalities. Previous studies highlighted the risk of crashes with roadside objects and the tendency of motorcyclists to ride with excessive speed on exclusive motorcycle lanes. However, the risk of same-direction crashes on exclusive motorcycle lanes was not explored in much detail, especially on the impact of lane geometry and roadside configurations. This study used naturalistic riding data to determine the effects of lane width and roadside configurations on overtaking speed, lateral position and likelihood of comfortable overtaking on tangential sections of an exclusive motorcycle lane. Twenty-nine recruited motorcyclists rode the instrumented motorcycles along a 20km stretch of an exclusive motorcycle lane along a major urban road. Results revealed that both the roadside configurations and lane width significantly affect the participants' lateral position, while the roadside configurations only affects the overtaking speed. Participants' overtaking speeds and the front motorcycles' lateral position contribute significantly to the likelihood of comfortable overtaking in exclusive motorcycle lanes. The findings highlight the importance of micro-level behavior indicators in improving the design and overall safety of the exclusive motorcycle facility.
  18. Isa N, Osman MS, Abdul Hamid H, Inderan V, Lockman Z
    Int J Phytoremediation, 2023;25(5):658-669.
    PMID: 35858487 DOI: 10.1080/15226514.2022.2099345
    This study describes the synthesis of silver nanoparticles (AgNPs) using shortleaf spikesedge extract (SSE) to reduce AgNO3. Visual observation, in addition to analyses of UV-vis, EDX, XRD, FTIR, and TEM was employed to monitor the formation of AgNPs. The effects of SSE concentration, AgNO3 concentration, reaction time, pH, and temperature on the synthesis of AgNPs were studied based on the surface plasmon resonance (SPR) band. From the TEM image, highly-scattered AgNPs of quasi-spherical shape with an average particle size of 17.64 nm, were observed. For the catalytic study, the reduction of methylene blue (MB) was evaluated using two systems. A detailed batch study of the removal efficiency (%RE) and kinetics was done at an ambient temperature, various MB initial concentrations, and varying reaction time. Employing the electron relay effect in System 2, the batch study clearly highlighted the significant role of AgNPs in boosting the catalytic activity for MB removal. At 30-100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. The kinetic data best fitted the pseudo-first-order model with a maximum reaction rate of 2.5715 min-1. These findings suggest the promising application of AgNPs in dye wastewater treatment.The SSE-driven AgNPs were prepared using unwanted dried biomass of shortleaf spikesedge extract (SSE) as a reducing as well as stabilizing agent. Employing the electron relay effect, the batch study clearly highlighted the significant role of SSE-driven AgNPs in boosting the catalytic activity for MB removal. At 30-100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. In this sense, SSE-driven AgNPs acted as an electron relay point that behaves alternatively as acceptor and donor of electrons. The findings revealed the good catalytic performance of SSE-driven AgNPS, proving their viability for dye wastewater treatment.
  19. Mohamad Aziz NA, Yunus R, Kania D, Abd Hamid H
    Molecules, 2021 Feb 03;26(4).
    PMID: 33546303 DOI: 10.3390/molecules26040788
    Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.
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