MyMedR

Displaying all 13 publications

Abstract:

Sort:

Fulltext Metal diagenesis and transport in coastal sediments around Penang Island , Malaysia

Khalik Wood, A., Zaharudin Ahmad, Noor Azhar Md. Shazili, Rosnan Yaakob, Carpenter, Roy

Journal of Nuclear and Related Technologies, 2004;2004(1):1-22.
MyJurnal

Spatial and temporal variations in concentrations of several metals and isotopes in sediment cores from around Penang Island, an area with economically important biological resources off the northwest coast of peninsular Malaysia, are reported. Because of a typical, monazite rich mineralogy in surrounding drainage basins, sedimentary metal enrichment factors relative to global average materials, enrichment factors (EFs) of ˃1.0 do not always indicate significant anthropogenic metal inputs. Because of extensive metal solubilization in the hot, organic carbon rich area, EFs of < 1.0 may be observed for several metals despite significant anthropogenic contributions. Comparison of metal-Al relationships in Penang area surface sediments with those in nearby and presumed uncontaminated Strait of Malacca sediments more accurately correct for atypical regional solubilization and mineralogical effects than comparison to global average materials. Such comparisons show concentrations of Cd, Cu, Pb, Ni, Cr, As, Sb, Zn and V have changed by less than a factor of two by anthropogenic discharges. Sedimentary concentration profiles of Pb, Zn and Cu, ratioed to Sc to normalize for variations in grain size and mineralogy, have subsurface maxima suggestive of modest and recently reduced anthropogenic inputs. Mn, U, As and Sb have Sc-normalized concentration profiles clearly affected by diagenetic processes. Sc-normalized profiles of Cr, Th, Ce and Sm show only small changes with depth, confirming insignificant anthropogenic inputs and undetectable postdepositional diagenetic mobility.
Excess ²¹⁰Pb activities and fluxes in Penang area sediments are limited by supply of this radionuclide, in contrast to sediments of both the northwestern U.S.A. and Amazon continental shelves, where they are limited by particle scavenging reactions.²¹⁰Pb activities in sediments of
the shallow, dynamic Penang area often show erratic or unconvincing changes with depth that
cannot be reliably modeled by assuming steady state, constant deposition rate of particles of
uniform chemistry, mineralogy and initial unsupported ²¹⁰Pb, and that mixing is limited to a
recognizable surface layer and resemble a diffusive process.
Radiation dose assessment at amang processing plants in Malaysia

Omar M, Sulaiman I, Hassan A, Wood AK

Radiat Prot Dosimetry, 2007;124(4):400-6.
PMID: 17510205

Measurements of external radiation level, radon/thoron daughters concentrations in air and uranium/thorium concentrations in airborne mineral dust at 16 amang plants in Malaysia were carried out for three consecutive months to assess radiation dose to workers. Estimated occupational dose was within the range of 1.7-10.9 mSv y(-1). The mean total dose at the amang plants was 4.1 mSv y(-1). Overall, it was found that the major dose contribution of 80% came from external radiation. Radon/thoron daughters and airborne mineral dust contributed to only 11 and 9% of the total dose, respectively.
Speciation of inorganic arsenic and selenium in leachates from landfills in relation to water quality assessment

Yusof AM, Salleh S, Wood AK

Biol Trace Elem Res, 1999;71-72:139-48.
PMID: 10676488

Speciation of arsenic and selenium was carried out on water samples taken from rivers used as water intake points in the vicinity of landfill areas used for land-based waste disposal system. Leachates from these landfill areas may contaminate the river water through underground seepage or overflowing, especially after a heavy downpour. Preconcentration of the chemical species was done using a mixture of ammonium pyrrolidinethiocarbamate-chloroform (APDTC-CHCl3). Because only the reduced forms of both arsenic and selenium species could be extracted by the preconcentrating mixture, suitable reducing agents such as 25% sodium thiosulfate for As(III) and 6M HCl for Se(IV) were used throughout the studies. Care was taken to exclude the interfering elements such as the alkali and alkali earth metals from the inorganic arsenic and selenium species by introducing 12% EDTA solution as the masking agent. The extracted mixture was irradiated in a thermal neutron flux of 4 x 10(12)/cm/s from a TRIGA Mk.II reactor at the Malaysia Institute of Nuclear Technology Research (MINT). Gamma rays of 559 keV and 297 keV from 76As and 75Se, respectively, were used in the quantitative determination of the inorganic species. Mixed standards of As(III) and Se(IV) used in the percentage efficiency procedure were prepared from salts of Analar grade. The water quality evaluation was viewed from the ratio of the inorganic species present.
The accumulation and distribution of trace metals in some localized marine species

Yusof AM, Rahman NA, Wood AK

Biol Trace Elem Res, 1994;43-45:239-49.
PMID: 7710833

Trace elements, such as As, Co, Cr, Hg, Sb, and Zn, were determined by neutron activation analysis (NAA), whereas Cd, Cu, and Pb were determined by graphite furnace atomic absorption spectroscopy (GFAAS) in clam, crab, prawn, swamp cerith, and mussel samples after digestion by microwave heating under controlled conditions before eluting the solutions through a column of a chelating resin, Chelex-100. The standard used in the determination of percentage volatile elements retained by microwave digestion and also in the activation process was Lobster Hepatopancreas TORT-1, whereas known mixed standards were prepared from nitrate salts to determine the efficiency of the separation procedure at a controlled pH. Mercury and lead detected in crabs exceeded the maximum permissible level. Some species also showed a high affinity toward certain elements, and their levels of accumulation in the tissues of these species corresponded with the concentration of these elements in sediments, especially at sites in the vicinity of an industrial zone.
Environmental 238U and 232Th concentration measurements in an area of high level natural background radiation at Palong, Johor, Malaysia

Ramli AT, Hussein AW, Wood AK

J Environ Radioact, 2005;80(3):287-304.
PMID: 15725504

Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.
Verification of MCNP simulation of neutron flux parameters at TRIGA MK II reactor of Malaysia

Yavar AR, Khalafi H, Kasesaz Y, Sarmani S, Yahaya R, Wood AK, et al.

Appl Radiat Isot, 2012 Oct;70(10):2488-93.
PMID: 22885391 DOI: 10.1016/j.apradiso.2012.06.015

A 3-D model for 1 MW TRIGA Mark II research reactor was simulated. Neutron flux parameters were calculated using MCNP-4C code and were compared with experimental results obtained by k(0)-INAA and absolute method. The average values of φ(th),φ(epi), and φ(fast) by MCNP code were (2.19±0.03)×10(12) cm(-2)s(-1), (1.26±0.02)×10(11) cm(-2)s(-1) and (3.33±0.02)×10(10) cm(-2)s(-1), respectively. These average values were consistent with the experimental results obtained by k(0)-INAA. The findings show a good agreement between MCNP code results and experimental results.
Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

Yavar AR, Sarmani SB, Wood AK, Fadzil SM, Radir MH, Khoo KS

Appl Radiat Isot, 2011 May;69(5):762-7.
PMID: 21295987 DOI: 10.1016/j.apradiso.2011.01.005

Determination of thermal to fast neutron flux ratio (f(fast)) and fast neutron flux (ϕ(fast)) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f(fast) and subsequently ϕ(fast) were determined using the absolute method. The f(fast) ranged from 48 to 155, and the ϕ(fast) was found in the range 1.03×10(10)-4.89×10(10) n cm(-2) s(-1). These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.
Radiological monitoring: terrestrial natural radionuclides in Kinta District, Perak, Malaysia

Lee SK, Wagiran H, Ramli AT, Apriantoro NH, Wood AK

J Environ Radioact, 2009 May;100(5):368-74.
PMID: 19299052 DOI: 10.1016/j.jenvrad.2009.01.001

Natural background gamma radiation and radioactivity concentrations were investigated from 2003 to 2005 in Kinta District, Perak, Malaysia. Sample locations were distant from any 'amang' processing plants. The external gamma dose rates ranged from 39 to 1039 nGy h(-1). The mean external gamma dose rate was 222+/-191 nG yh(-1). Small areas of relatively enhanced activity were located having external gamma dose rates of up to 1039+/-104 nGy h(-1). The activity concentrations of (238)U, (232)Th and (40)K were analyzed by using a high-resolution co-axial HPGe detector system. The activity concentration ranges were 12-426 Bq kg(-1) for (238)U, 19-1377 Bq kg(-1) for (232)Th and <19-2204 Bq kg(-1) for (40)K. Based on the radioactivity levels determined, the gamma-absorbed dose rates in air at 1m above the ground were calculated. The calculated dose rates and measured dose rates had a good correlation coefficient, R of 0.94. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate and the mean population weighted dose rate were calculated. An isodose map for the Kinta District was also produced.
Differentiation of elemental composition of normal and malignant breast tissue by instrumental neutron activation analysis

Ng KH, Bradley DA, Looi LM, Mahmood CS, Wood AK

Appl Radiat Isot, 1993 Mar;44(3):511-6.
PMID: 8472024

Multi-elemental quantitative analyses of 15 paired samples of normal and malignant human breast tissue by instrumental neutron activation analysis are reported. The elements, Al, Br, Ca, Cl, Co, Cs, Fe, K, Na, Rb, Zn were detected. Significantly elevated concentration levels were found for Al, Br, Ca, Cl, Cs, K, Na, Zn in malignant compared to normal tissue. Although the role of elemental composition in breast cancer is unclear, this finding may be of importance as another parameter for differentiating normal from malignant tissue.
Modulation of the mechanical responses of synovial fibroblasts by osteoarthritis-associated inflammatory stressors

Jamal J, Roebuck MM, Lee SY, Frostick SP, Abbas AA, Merican AM, et al.

Int J Biochem Cell Biol, 2020 09;126:105800.
PMID: 32673644 DOI: 10.1016/j.biocel.2020.105800

OBJECTIVES: To compare mechanobiological response of synovial fibroblasts (SFb) from OA patient cohorts under mechanical load and inflammatory stressors for better understanding of SFb homeostatic functions.
METHODS: Primary SFb isolated from knee synovium of OA obese (OA-ob:SFb), OA-pre-obese (OA-Pob:SFb), non-OA arthroscopic (scope:SFb), and non-OA arthroscopic with cartilage damage (scope-CD:SFb) were exposed to OA-conditioned media (OACM), derived from OA obese (OA-ob:CM), OA-pre-obese (OA-Pob:CM), and mechanical stretch at either 0 %, 6 % or 10 % for 24 h. Differences in the mRNA levels of genes involved in extracellular matrix production, inflammation and secretory activity were measured.
RESULTS: Despite the significant BMI differences between the OA-ob and OA-Pob groups, OA-Pob has more patients with underlying dyslipidaemia, and low-grade synovitis with higher levels of secreted proteins, CXCL8, COL4A1, CCL4, SPARC and FGF2 in OA-Pob:CM. All primary SFb exhibited anti-proliferative activity with both OA-CM. Mechanical stretch stimulated lubricin production in scope:SFb, higher TGFβ1 and COL1A1 expressions in scope-CD:SFb. OA-Pob:CM stimulated greater detrimental effects than the OA-ob:CM, with higher pro-inflammatory cytokines, IL1β, IL6, COX2 and proteases such as aggrecanases, ADAMTS4 and ADAMTS5, and lower ECM matrix, COL1A1 expressions in all SFb. OA-ob:SFb were unresponsive but expressed higher pro-inflammatory cytokines under OA-Pob:CM treatment.
CONCLUSION: Both mechanical and inflammatory stressors regulate SFb molecular functions with heterogeneity in responses that are dependent on their pathological tissue of origins. While mechanical stretch promotes a favorable effect with enhanced lubricin production in scope:SFb and TGFβ1 and COL1A1 in scope-CD:SFb, the presence of excessively high OA-associated inflammatory mediators in OA-Pob:CM, predominantly SPARC, CXCL8 and FGF2 drive all SFb regardless of pathology, towards greater pro-inflammatory activities.
Fulltext New and Interesting Fungi. 2

Crous PW, Schumacher RK, Akulov A, Thangavel R, Hernández-Restrepo M, Carnegie AJ, et al.

Fungal Syst Evol, 2019 Jun;3:57-134.
PMID: 32467898 DOI: 10.3114/fuse.2019.03.06

One order, seven families, 28 new genera, 72 new species, 13 new combinations, four epitypes, and interesting new host and / or geographical records are introduced in this study. Pseudorobillardaceae is introduced for Pseudorobillarda (based on P. phragmitis). New genera include: Jeremyomyces (based on J. labinae) on twigs of Salix alba (Germany); Neodothidotthia (based on N. negundinicola) on Acer negundo (Ukraine); Neomedicopsis (based on N. prunicola) on fallen twigs of Prunus padus (Ukraine); Neophaeoappendicospora (based on N. leucaenae) on Leucaena leucocephala (France) (incl. Phaeoappendicosporaceae); Paradevriesia (incl. Paradevriesiaceae) (based on P. americana) from air (USA); Phaeoseptoriella (based on P. zeae) on leaves of Zea mays (South Africa); Piniphoma (based on P. wesendahlina) on wood debris of Pinus sylvestris (Germany); Pseudoconiothyrium (based on P. broussonetiae) on branch of Broussonetia papyrifera (Italy); Sodiomyces (based on S. alkalinus) from soil (Mongolia), and Turquoiseomyces (incl. Turquoiseomycetales and Turquoiseomycetaceae) (based on T. eucalypti) on leaves of Eucalyptus leptophylla (Australia); Typhicola (based on T. typharum) on leaves of Typha sp. (Germany); Xenodevriesia (incl. Xenodevriesiaceae) (based on X. strelitziicola) on leaves of Strelitzia sp. (South Africa). New species include: Bacillicladium clematidis on branch of Clematis vitalbae (Austria); Cercospora gomphrenigena on leaves of Gomphrena globosa (South Africa); Cyphellophora clematidis on Clematis vitalba (Austria); Exophiala abietophila on bark of Abies alba (Norway); Exophiala lignicola on fallen decorticated trunk of Quercus sp. (Ukraine); Fuscostagonospora banksiae on Banksia sp. (Australia); Gaeumannomycella caricicola on dead leaf of Carex remota (Germany); Hansfordia pruni on Prunus persica twig (Italy) (incl. Hansfordiaceae); Microdochium rhopalostylidis on Rhopalostylis sapida (New Zealand); Neocordana malayensis on leaves of Musa sp. (Malaysia); Neocucurbitaria prunicola on fallen twigs of Prunus padus (Ukraine); Neocucurbitaria salicis-albae on Salix alba twig (Ukraine); Neohelicomyces deschampsiae on culm base of dead leaf sheath of Deschampsia cespitosa (Germany); Pararoussoella juglandicola on twig of Juglans regia (Germany); Pezicula eucalyptigena on leaves of Eucalyptus sp. (South Africa); Phlogicylindrium dunnii on leaves of Eucalyptus dunnii (Australia); Phyllosticta hagahagaensis on leaf litter of Carissa bispinosa (South Africa); Phyllosticta austroafricana on leaf spots of unidentified deciduous tree host (South Africa); Pseudosigmoidea alnicola on Alnus glutinosa leaf litter (Germany); Pseudoteratosphaeria africana on leaf spot on unidentified host (Angola); Porodiplodia vitis on canes of Vitis vinifera (USA); Sodiomyces alkalinus from soil (Mongolia), Sodiomyces magadiensis and Sodiomyces tronii from soil (Kenya), Sympodiella quercina on fallen leaf of Quercus robur (Germany) and Zasmidium hakeicola on leaves of Hakea corymbosa (Australia). Epitypes are designated for: Cryptostictis falcata on leaves of E. alligatrix (Australia), Hendersonia phormii on leaves of Phormium tenax (New Zealand), Sympodiella acicola on needles of Pinus sylvestris (Netherlands), and Sphaeria scirpicola var. typharum on leaf of Typha sp. (Germany). Several taxa originally described from rocks are validated in this study. New taxa include: Extremaceae fam. nov., and new genera, Arthrocatena, Catenulomyces, Constantinomyces, Extremus, Hyphoconis, Incertomyces, Lapidomyces, Lithophila, Monticola, Meristemomyces, Oleoguttula, Perusta, Petrophila, Ramimonilia, Saxophila and Vermiconidia. New species include: Arthrocatena tenebrosa, Catenulomyces convolutus, Constantinomyces virgultus, C. macerans, C. minimus, C. nebulosus, C. virgultus, Exophiala bonariae, Extremus adstrictus, E. antarcticus, Hyphoconis sterilis, Incertomyces perditus, Knufia karalitana, K. marmoricola, K. mediterranea, Lapidomyces hispanicus, Lithophila guttulata, Monticola elongata, Meristemomyces frigidus, M. arctostaphyli, Neodevriesia bulbillosa, N. modesta, N. sardiniae, N. simplex, Oleoguttula mirabilis, Paradevriesia compacta, Perusta inaequalis, Petrophila incerta, Rachicladosporium alpinum, R. inconspicuum, R. mcmurdoi, R. monterosanum, R. paucitum, Ramimonilia apicalis, Saxophila tyrrhenica, Vermiconidia antarctica, V. calcicola, V. foris, and V. flagrans.
Fulltext Investigating Genetic and Other Determinants of First-Onset Myocardial Infarction in Malaysia: Protocol for the Malaysian Acute Vascular Events Risk Study

Chowdhury R, Noh MFM, Ismail SR, van Daalen KR, Kamaruddin PSNM, Zulkiply SH, et al.

JMIR Res Protoc, 2022 Feb 10;11(2):e31885.
PMID: 35142634 DOI: 10.2196/31885

BACKGROUND: Although the burden of premature myocardial infarction (MI) is high in Malaysia, direct evidence on the determinants of MI in this multi-ethnic population remains sparse.
OBJECTIVE: The Malaysian Acute Vascular Events Risk (MAVERIK) study is a retrospective case-control study established to investigate the genomic, lipid-related, and other determinants of acute MI in Malaysia. In this paper, we report the study protocol and early results.
METHODS: By June 2019, we had enrolled approximately 2500 patients with their first MI and 2500 controls without cardiovascular disease, who were frequency-matched by age, sex, and ethnicity, from 17 hospitals in Malaysia. For each participant, serum and whole blood have been collected and stored. Clinical, demographic, and behavioral information has been obtained using a 200-item questionnaire.
RESULTS: Tobacco consumption, a history of diabetes, hypertension, markers of visceral adiposity, indicators of lower socioeconomic status, and a family history of coronary disease were more prevalent in cases than in controls. Adjusted (age and sex) logistic regression models for traditional risk factors indicated that current smoking (odds ratio [OR] 4.11, 95% CI 3.56-4.75; P30 kg/m2; OR 1.19, 95% CI 1.05-1.34; P=.009) were associated with MI in age- and sex-adjusted models.
CONCLUSIONS: The MAVERIK study can serve as a useful platform to investigate genetic and other risk factors for MI in an understudied Southeast Asian population. It should help to hasten the discovery of disease-causing pathways and inform regionally appropriate strategies that optimize public health action.
INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/31885.
Fulltext Fungal Planet description sheets: 320-370

Crous PW, Wingfield MJ, Guarro J, Hernández-Restrepo M, Sutton DA, Acharya K, et al.

Persoonia, 2015 Jun;34:167-266.
PMID: 26240451 DOI: 10.3767/003158515X688433

Novel species of fungi described in the present study include the following from Malaysia: Castanediella eucalypti from Eucalyptus pellita, Codinaea acacia from Acacia mangium, Emarcea eucalyptigena from Eucalyptus brassiana, Myrtapenidiella eucalyptorum from Eucalyptus pellita, Pilidiella eucalyptigena from Eucalyptus brassiana and Strelitziana malaysiana from Acacia mangium. Furthermore, Stachybotrys sansevieriicola is described from Sansevieria ehrenbergii (Tanzania), Phacidium grevilleae from Grevillea robusta (Uganda), Graphium jumulu from Adansonia gregorii and Ophiostoma eucalyptigena from Eucalyptus marginata (Australia), Pleurophoma ossicola from bone and Plectosphaerella populi from Populus nigra (Germany), Colletotrichum neosansevieriae from Sansevieria trifasciata, Elsinoë othonnae from Othonna quinquedentata and Zeloasperisporium cliviae (Zeloasperisporiaceae fam. nov.) from Clivia sp. (South Africa), Neodevriesia pakbiae, Phaeophleospora hymenocallidis and Phaeophleospora hymenocallidicola on leaves of a fern (Thailand), Melanconium elaeidicola from Elaeis guineensis (Indonesia), Hormonema viticola from Vitis vinifera (Canary Islands), Chlorophyllum pseudoglobossum from a grassland (India), Triadelphia disseminata from an immunocompromised patient (Saudi Arabia), Colletotrichum abscissum from Citrus (Brazil), Polyschema sclerotigenum and Phialemonium limoniforme from human patients (USA), Cadophora vitícola from Vitis vinifera (Spain), Entoloma flavovelutinum and Bolbitius aurantiorugosus from soil (Vietnam), Rhizopogon granuloflavus from soil (Cape Verde Islands), Tulasnella eremophila from Euphorbia officinarum subsp. echinus (Morocco), Verrucostoma martinicensis from Danaea elliptica (French West Indies), Metschnikowia colchici from Colchicum autumnale (Bulgaria), Thelebolus microcarpus from soil (Argentina) and Ceratocystis adelpha from Theobroma cacao (Ecuador). Myrmecridium iridis (Myrmecridiales ord. nov., Myrmecridiaceae fam. nov.) is also described from Iris sp. (The Netherlands). Novel genera include (Ascomycetes): Budhanggurabania from Cynodon dactylon (Australia), Soloacrosporiella, Xenocamarosporium, Neostrelitziana and Castanediella from Acacia mangium and Sabahriopsis from Eucalyptus brassiana (Malaysia), Readerielliopsis from basidiomata of Fuscoporia wahlbergii (French Guyana), Neoplatysporoides from Aloe ferox (Tanzania), Wojnowiciella, Chrysofolia and Neoeriomycopsis from Eucalyptus (Colombia), Neophaeomoniella from Eucalyptus globulus (USA), Pseudophaeomoniella from Olea europaea (Italy), Paraphaeomoniella from Encephalartos altensteinii, Aequabiliella, Celerioriella and Minutiella from Prunus (South Africa). Tephrocybella (Basidiomycetes) represents a novel genus from wood (Italy). Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

Filters

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

External Links