Displaying publications 1 - 20 of 23 in total

  1. Paul FM
    Med J Malaysia, 1982 Dec;37(4):357-61.
    PMID: 6300621
    Consideration. is gzven to the recognition and prevention of carious types of mental retardation due to hazards of environmental origin. Observations are presented on congenital syphilis, congenital toxoplasmosis, congenital rubella, Singapore kernicterus, Japanese B encephalitis, and tuberculous meningitis. Appropriate preventiue measures have resulted in a significant reduction in Singapore of these conditions, and hence in a decreased frequency of environmentally determined mental retardation. and related disabilities.
  2. Paul FM
    Singapore Med J, 1974 Dec;15(4):231-40.
    PMID: 4458066
    Ninety-six cases of severe malnutrition and associated nutritional disorders were encountered in children in the department of paediatrics for the year 1971. The predominant age group was in children under the age of two years. Malay and Indian children were affected more than the Chinese children with malnutrition. Protein caloric malnutrition had already affected the growth pattern of these children as the majority were below the 50th percentile in height and weight comparing them with Hong Kong childrens’ height and weight standards. Seventy-five per cent of the children presented with infection. Fifty-four per cent of the families with malnutrition had three to six children and in two thirds of the families the income was from $100/- to $249/- per month. Forty per cent of the children lived in the kampong type of houses with no proper sanitation. Worm infestation was common in this group. The mean haemoglobin, serum iron levels, and serum folic acid levels were lower in the Indians and Malays. Protein caloric malnutrition must be treated early because of its irreversible effects on brain and bone growth. It is recommended that some form of allowance either in the form of food or money be given to these children from poor social-economic background.
  3. Hue KY, Lew JH, Myo Thant MM, Matar OK, Luckham PF, Müller EA
    Molecules, 2023 Aug 31;28(17).
    PMID: 37687196 DOI: 10.3390/molecules28176367
    In poorly consolidated carbonate rock reservoirs, solids production risk, which can lead to increased environmental waste, can be mitigated by injecting formation-strengthening chemicals. Classical atomistic molecular dynamics (MD) simulation is employed to model the interaction of polyacrylamide-based polymer additives with a calcite structure, which is the main component of carbonate formations. Amongst the possible calcite crystal planes employed as surrogates of reservoir rocks, the (1 0 4) plane is shown to be the most suitable surrogate for assessing the interactions with chemicals due to its stability and more realistic representation of carbonate structure. The molecular conformation and binding energies of pure polyacrylamide (PAM), hydrolysed polyacrylamide in neutral form (HPAM), hydrolysed polyacrylamide with 33% charge density (HPAM 33%) and sulfonated polyacrylamide with 33% charge density (SPAM 33%) are assessed to determine the adsorption characteristics onto calcite surfaces. An adsorption-free energy analysis, using an enhanced umbrella sampling method, is applied to evaluate the chemical adsorption performance. The interaction energy analysis shows that the polyacrylamide-based polymers display favourable interactions with the calcite structure. This is attributed to the electrostatic attraction between the amide and carboxyl functional groups with the calcite. Simulations confirm that HPAM33% has a lower free energy than other polymers, presumably due to the presence of the acrylate monomer in ionised form. The superior chemical adsorption performance of HPAM33% agrees with Atomic Force Microscopy experiments reported herein.
  4. Lew JH, Matar OK, Müller EA, Luckham PF, Sousa Santos A, Myo Thant MM
    Polymers (Basel), 2023 Oct 10;15(20).
    PMID: 37896286 DOI: 10.3390/polym15204037
    In this work, the interaction of hydrolysed polyacrylamide (HPAM) of two molecular weights (F3330, 11-13 MDa; F3530, 15-17 MDa) with calcium carbonate (CaCO3) was studied via atomic force microscopy (AFM). In the absence of polymers at 1.7 mM and 1 M NaCl, good agreement with DLVO theory was observed. At 1.7 mM NaCl, repulsive interaction during approach at approximately 20 nm and attractive adhesion of approximately 400 pN during retraction was measured, whilst, at 1 M NaCl, no repulsion during approach was found. Still, a significantly larger adhesion of approximately 1400 pN during retraction was observed. In the presence of polymers, results indicated that F3330 displayed higher average adhesion (450-625 pN) and interaction energy (43-145 aJ) with CaCO3 than F3530's average adhesion (85-88 pN) and interaction energy (8.4-11 aJ). On the other hand, F3530 exerted a longer steric repulsion distance (70-100 nm) than F3330 (30-70 nm). This was likely due to the lower molecular weight. F3330 adopted a flatter configuration on the calcite surface, creating more anchor points with the surface in the form of train segments. The adhesion and interaction energy of both HPAM with CaCO3 can be decreased by increasing the salt concentration. At 3% NaCl, the average adhesion and interaction energy of F3330 was 72-120 pN and 5.6-17 aJ, respectively, while the average adhesion and interaction energy of F3530 was 11.4-48 pN and 0.3-2.98 aJ, respectively. The reduction of adhesion and interaction energy was likely due to the screening of the COO- charged group of HPAM by salt cations, leading to a reduction of electrostatic attraction between the negatively charged HPAM and the positively charged CaCO3.
  5. Miyaji K, Paul F, Shahrizaila N, Umapathi T, Yuki N
    J Neuroimmunol, 2014 Nov 15;276(1-2):172-4.
    PMID: 25156074 DOI: 10.1016/j.jneuroim.2014.08.004
    Given their localization and important role in regulating complement, complement regulatory proteins may act as target antigens and their antibodies as biomarkers in demyelinating neuropathies. We investigated the binding of autoantibodies to complement regulatory proteins (CD46, 55 and 59) in demyelinating diseases. In 42 acute inflammatory demyelinating polyneuropathy, 23 chronic inflammatory demyelinating polyneuropathy, 13 acute motor axonal neuropathy, 71 multiple sclerosis, and 19 neuromyelitis optica patients as well as 55 healthy controls, we were unable to detect significant titers of antibodies to CD46, CD55 and CD59. These autoantibodies are unlikely to be biomarkers in acute and chronic inflammatory demyelinating polyneuropathies.
  6. Miyaji K, Paul F, Shahrizaila N, Umapathi T, Yuki N
    J Neuroimmunol, 2016 Feb 15;291:78-81.
    PMID: 26857499 DOI: 10.1016/j.jneuroim.2015.12.012
    Tetraspanin family proteins, CD9, CD81 and CD82 are expressed in the oligodendrocytes and Schwann cells. We investigated autoantibodies to tetraspanin proteins in patients with demyelinating diseases. Sera were collected from 119 multiple sclerosis patients, 19 neuromyelitis optica, 42 acute inflammatory demyelinating polyneuropathy, 23 chronic inflammatory demyelinating polyneuropathy and 13 acute motor axonal neuropathy as well as 55 healthy controls. Few multiple sclerosis and acute inflammatory demyelinating polyneuropathy patients had autoantibodies that were weakly reactive to CD9 or CD81 but the significance is unclear. It is unlikely that these autoantibodies are pathogenic or serve as potential biomarkers in demyelinating diseases.
  7. George GN, Gailer J, Ponomarenko O, La Porte PF, Strait K, Alauddin M, et al.
    J Inorg Biochem, 2016 05;158:24-29.
    PMID: 26883676 DOI: 10.1016/j.jinorgbio.2016.01.022
    Certain arsenic and selenium compounds show a remarkable mutual cancelation of toxicities, where a lethal dose of one can be voided by an equimolar and otherwise lethal dose of the other. It is now well established that the molecular basis of this antagonism is the formation and biliary excretion of seleno bis-(S-glutathionyl) arsinium anion [(GS)2AsSe](-). Previous work has definitively demonstrated the presence of [(GS)2AsSe](-) in rabbit bile, but only in the presence of other arsenic and selenium species. Rabbits have a gall bladder, which concentrates bile and lowers its pH; it seems likely that this may be responsible for the breakdown of biliary [(GS)2AsSe](-). Since rats have no gall bladder, the bile proceeds directly through the bile duct from the hepatobiliary tree. In the present work we have shown that the primary product of biliary co-excretion of arsenic and selenium in rats is [(GS)2AsSe](-), with essentially 100% of the arsenic and selenium present as this species. The chemical plausibility of the X-ray absorption spectroscopy-derived structural conclusions of this novel arsenic and selenium co-excretion product is supported by density functional theory calculations. These results establish the biomolecular basis to further explore the use of selenium dietary supplements as a possible palliative for chronic low-level arsenic poisoning of human populations.
  8. Ponomarenko O, La Porte PF, Singh SP, Langan G, Fleming DEB, Spallholz JE, et al.
    Metallomics, 2017 Nov 15;9(11):1585-1595.
    PMID: 29058732 DOI: 10.1039/c7mt00201g
    Arsenicosis, a syndrome caused by ingestion of arsenic contaminated drinking water, currently affects millions of people in South-East Asia and elsewhere. Previous animal studies revealed that the toxicity of arsenite essentially can be abolished if selenium is co-administered as selenite. Although subsequent studies have provided some insight into the biomolecular basis of this striking antagonism, many details of the biochemical pathways that ultimately result in the detoxification and excretion of arsenic using selenium supplements have yet to be thoroughly studied. To this end and in conjunction with the recent Phase III clinical trial "Selenium in the Treatment of Arsenic Toxicity and Cancers", we have applied synchrotron X-ray techniques to elucidate the mechanisms of this arsenic-selenium antagonism at the tissue and organ levels using an animal model. X-ray fluorescence imaging (XFI) of cryo-dried whole-body sections of laboratory hamsters that had been injected with arsenite, selenite, or both chemical species, provided insight into the distribution of both metalloids 30 minutes after treatment. Co-treated animals showed strong co-localization of arsenic and selenium in the liver, gall bladder and small intestine. X-ray absorption spectroscopy (XAS) of freshly frozen organs of co-treated animals revealed the presence in liver tissues of the seleno bis-(S-glutathionyl) arsinium ion, which was rapidly excreted via bile into the intestinal tract. These results firmly support the previously postulated hepatobiliary excretion of the seleno bis-(S-glutathionyl) arsinium ion by providing the first data pertaining to organs of whole animals.
  9. de Jong S, Diniz MJA, Saloma A, Gadelha A, Santoro ML, Ota VK, et al.
    Commun Biol, 2018;1:163.
    PMID: 30320231 DOI: 10.1038/s42003-018-0155-y
    Psychiatric disorders are thought to have a complex genetic pathology consisting of interplay of common and rare variation. Traditionally, pedigrees are used to shed light on the latter only, while here we discuss the application of polygenic risk scores to also highlight patterns of common genetic risk. We analyze polygenic risk scores for psychiatric disorders in a large pedigree (n ~ 260) in which 30% of family members suffer from major depressive disorder or bipolar disorder. Studying patterns of assortative mating and anticipation, it appears increased polygenic risk is contributed by affected individuals who married into the family, resulting in an increasing genetic risk over generations. This may explain the observation of anticipation in mood disorders, whereby onset is earlier and the severity increases over the generations of a family. Joint analyses of rare and common variation may be a powerful way to understand the familial genetics of psychiatric disorders.
  10. Horm SV, Mardy S, Rith S, Ly S, Heng S, Vong S, et al.
    PLoS One, 2014;9(10):e110713.
    PMID: 25340711 DOI: 10.1371/journal.pone.0110713
    BACKGROUND: The Cambodian National Influenza Center (NIC) monitored and characterized circulating influenza strains from 2009 to 2011.

    METHODOLOGY/PRINCIPAL FINDINGS: Sentinel and study sites collected nasopharyngeal specimens for diagnostic detection, virus isolation, antigenic characterization, sequencing and antiviral susceptibility analysis from patients who fulfilled case definitions for influenza-like illness, acute lower respiratory infections and event-based surveillance. Each year in Cambodia, influenza viruses were detected mainly from June to November, during the rainy season. Antigenic analysis show that A/H1N1pdm09 isolates belonged to the A/California/7/2009-like group. Circulating A/H3N2 strains were A/Brisbane/10/2007-like in 2009 before drifting to A/Perth/16/2009-like in 2010 and 2011. The Cambodian influenza B isolates from 2009 to 2011 all belonged to the B/Victoria lineage represented by the vaccine strains B/Brisbane/60/2008 and B/Malaysia/2506/2004. Sequences of the M2 gene obtained from representative 2009-2011 A/H3N2 and A/H1N1pdm09 strains all contained the S31N mutation associated with adamantanes resistance except for one A/H1N1pdm09 strain isolated in 2011 that lacked this mutation. No reduction in the susceptibility to neuraminidase inhibitors was observed among the influenza viruses circulating from 2009 to 2011. Phylogenetic analysis revealed that A/H3N2 strains clustered each year to a distinct group while most A/H1N1pdm09 isolates belonged to the S203T clade.

    CONCLUSIONS/SIGNIFICANCE: In Cambodia, from 2009 to 2011, influenza activity occurred throughout the year with peak seasonality during the rainy season from June to November. Seasonal influenza epidemics were due to multiple genetically distinct viruses, even though all of the isolates were antigenically similar to the reference vaccine strains. The drug susceptibility profile of Cambodian influenza strains revealed that neuraminidase inhibitors would be the drug of choice for influenza treatment and chemoprophylaxis in Cambodia, as adamantanes are no longer expected to be effective.

  11. Searchfield GD, Zhang J, Biswas R, De Ridder D, Deutsch B, Hall DA, et al.
    PMID: 34291436 DOI: 10.1007/7854_2021_230
  12. Searchfield GD, Zhang J, Biswas R, De Ridder D, Deutsch B, Hall DA, et al.
    Curr Top Behav Neurosci, 2021;51:461-483.
    PMID: 33665781 DOI: 10.1007/7854_2020_217
    This volume has highlighted the many recent advances in tinnitus theory, models, diagnostics, therapies, and therapeutics. But tinnitus knowledge is far from complete. In this chapter, contributors to the Behavioral Neuroscience of Tinnitus consider emerging topics and areas of research needed in light of recent findings. New research avenues and methods to explore are discussed. Issues pertaining to current assessment, treatment, and research methods are outlined, along with recommendations on new avenues to explore with research.
  13. Coleman JRI, Peyrot WJ, Purves KL, Davis KAS, Rayner C, Choi SW, et al.
    Mol Psychiatry, 2020 Jul;25(7):1430-1446.
    PMID: 31969693 DOI: 10.1038/s41380-019-0546-6
    Depression is more frequent among individuals exposed to traumatic events. Both trauma exposure and depression are heritable. However, the relationship between these traits, including the role of genetic risk factors, is complex and poorly understood. When modelling trauma exposure as an environmental influence on depression, both gene-environment correlations and gene-environment interactions have been observed. The UK Biobank concurrently assessed Major Depressive Disorder (MDD) and self-reported lifetime exposure to traumatic events in 126,522 genotyped individuals of European ancestry. We contrasted genetic influences on MDD stratified by reported trauma exposure (final sample size range: 24,094-92,957). The SNP-based heritability of MDD with reported trauma exposure (24%) was greater than MDD without reported trauma exposure (12%). Simulations showed that this is not confounded by the strong, positive genetic correlation observed between MDD and reported trauma exposure. We also observed that the genetic correlation between MDD and waist circumference was only significant in individuals reporting trauma exposure (rg = 0.24, p = 1.8 × 10-7 versus rg = -0.05, p = 0.39 in individuals not reporting trauma exposure, difference p = 2.3 × 10-4). Our results suggest that the genetic contribution to MDD is greater when reported trauma is present, and that a complex relationship exists between reported trauma exposure, body composition, and MDD.
  14. Hor JY, Asgari N, Nakashima I, Broadley SA, Leite MI, Kissani N, et al.
    Front Neurol, 2020;11:501.
    PMID: 32670177 DOI: 10.3389/fneur.2020.00501
    Neuromyelitis optica spectrum disorder (NMOSD) is an uncommon inflammatory disease of the central nervous system, manifesting clinically as optic neuritis, myelitis, and certain brain and brainstem syndromes. Cases clinically diagnosed as NMOSD may include aquaporin 4 (AQP4)-antibody-seropositive autoimmune astrocytopathic disease, myelin oligodendrocyte glycoprotein (MOG)-antibody-seropositive inflammatory demyelinating disease, and double-seronegative disease. AQP4-antibody disease has a high female-to-male ratio (up to 9:1), and its mean age at onset of ~40 years is later than that seen in multiple sclerosis. For MOG-antibody disease, its gender ratio is closer to 1:1, and it is more common in children than in adults. Its clinical phenotypes differ but overlap with those of AQP4-antibody disease and include acute disseminated encephalomyelitis, brainstem and cerebral cortical encephalitis, as well as optic neuritis and myelitis. Double-seronegative disease requires further research and clarification. Population-based studies over the past two decades report the prevalence and incidence of NMOSD in different populations worldwide. One relevant finding is the varying prevalence observed in different racial groups. Consistently, the prevalence of NMOSD among Whites is ~1/100,000 population, with an annual incidence of <1/million population. Among East Asians, the prevalence is higher, at ~3.5/100,000 population, while the prevalence in Blacks may be up to 10/100,000 population. For MOG-antibody disease, hospital-based studies largely do not observe any significant racial preponderance so far. This disorder comprises a significant proportion of NMOSD cases that are AQP4-antibody-seronegative. A recent Dutch nationwide study reported the annual incidence of MOG-antibody disease as 1.6/million population (adult: 1.3/million, children: 3.1/million). Clinical and radiological differences between AQP4-antibody and MOG-antibody associated diseases have led to interest in the revisions of NMOSD definition and expanded stratification based on detection of a specific autoantibody biomarker. More population-based studies in different geographical regions and racial groups will be useful to further inform the prevalence and incidence of NMOSD and their antibody-specific subgroups. Accessibility to AQP4-antibody and MOG-antibody testing, which is limited in many centers, is a challenge to overcome. Environmental and genetic studies will be useful accompaniments to identify other potential pathogenetic factors and specific biomarkers in NMOSD.
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