Displaying publications 1 - 20 of 35 in total

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  1. Muhammad Barzani Gasim, Salmijah Surif, Sahibin Abd. Rahim, Chong HB, Mohd. Ekhwan Toriman, Mazlin Mokhtar
    Kajian ini bertujuan untuk mengenal pasti punca berlakunya banjir di Segamat pada 17 hingga 21 Disember 2006. Kegiatan termasuklah mengumpul, menilai dan mengalisis data taburan hujan dari Januari 1998 hingga Disember 2006 serta menganalisis data telemetri harian bagi aras dan luahan air sungai pada Disember 2006. Satu set data hujan harian, bulanan dan tahunan dari Stesen Felda Medoi, Segamat telah dianalisis dan dihubungkait dengan data telemetri. Data taburan hujan selama 8 tahun tersebut menunjukkan kawasan Bandar Segamat menerima hujan bulanan yang berjulat daripada 2.5 mm (Februari 2004) sehingga 536.8 mm (Januari 2003). Taburan hujan bulanan Oktober sehingga Disember 2006 menunjukkan kenaikan secara positif, iaitu daripada 118 mm sehingga 435 mm/bulan tetapi berlaku penurunan (392 mm) pada Januari 2007. Hasil kajian menunjukkan bahawa hujan lebat yang luar biasa dan keadaan bentuk topografi yang rendah dan beralun di kawasan kajian adalah penyebab utama banjir di Segamat.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  2. Sanusi W, Abdul Aziz Jemain, Wan Zawiah Wan Zin
    Sains Malaysiana, 2014;43:1791-1800.
    Dalam kajian ini, pendekatan pengelompokan kabur Gustafson-Kessel (Gx) telah digunakan untuk mengelaskan 35 stesen hujan di Semenanjung Malaysia ke dalam rantau homogen. Pertama, algoritma pengelompokan kabur GK digunakan untuk mengenal pasti rantau awal. Kemudian, diuji keserasian dan kehomogenan rantau berkenaan. Akhir sekali, penyesuaian rantau dilakukan untuk mendapatkan rantau homogen. Hasil kajian mendapati 35 stesen hujan kajian boleh dibahagikan kepada enam rantau yang homogen. Rantau 1 meliputi bahagian barat laut dan utara Semenanjung Malaysia, rantau 2, 3 dan 4 meliputi bahagian barat, rantau 5 meliputi bahagian barat daya dan rantau 6 meliputi bahagian timur. Hasil kajian ini juga memperlihatkan bahawa berdasarkan nilai purata Indeks Kerpasan Piawai (sPi) skala masa satu bulan, rantau 2 lebih sering mengalami keadaan kemarau melampau. Walau bagaimanapun, berdasarkan sPi skala masa satu bulan, peristiwa kemarau terjadi secara rawak dalam semua rantau yang dianalisis , bahkan semua rantau tersebut pernah mengalami kejadian kemarau melampau dalam tempoh masa setahun. Hasil kajian ini turut menunjukkan bahawa pendekatan pengelompokan kabur Gustafson-Kessel boleh digunakan untuk membina rantau homogen.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  3. Ahmad A, Shuhaimi Othman M, Lim E, Abd. Aziz Z
    Sains Malaysiana, 2013;42:587-596.
    Satu analisis penentuan parameter kualiti air yang penting untuk penilaian ekosistem cetek telah dilakukan menggunakan kaedah multivariat. Sebanyak 14 parameter kualiti air yang melibatkan komponen biologi, fizik dan kimia telah dikumpulkan setiap bulan selama satu tahun. Data dianalisis menggunakan ujian faktor yang melibatkan tiga proses iaitu mengenal pasti korelasi antara faktor, mengekstrak faktor dan seterusnya melihat kesan gabungan faktor-faktor tersebut. Proses pertama melibatkan pengelompokkan parameter yang berkorelasi kuat ke dalam faktor tersendiri dan mengeluarkan parameter yang mempunyai lebih daripada satu faktor. Analisis pengelasan agglomeratif hierarki (HACA) dan analisis diskriminan (DA) juga dilakukan untuk memperlihatkan kelompokan dan pengaruh faktor terhadap kualiti air tasik. Hasil analisis menunjukkan kualiti air Tasik Chini dipengaruhi oleh lebih daripada satu faktor. Hasil kajian menunjukkan komponen biologi dan kimia (nutrien) mempunyai pengaruh kuat dalam penentuan kualiti air tasik. Parameter berasaskan biologi iaitu BOD5, COD, klorofil a dan kimia (nitrat dan ortofosfat) adalah parameter yang
    penting di Tasik Chini. Ketiga-tiga analisis yang dijalankan menunjukkan kepentingan penentuan komponen biologi dan kimia bagi menentukan kualiti air Tasik Chini.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  4. Ghani RA, Nasir R, Wan Shahrazad WS, Yusooff F
    Jurnal Psikologi Malaysia, 2013;olume 27:3-14.
    Kajian kuasai-eksperimental ini dijalankan bertujuan untuk mengukur kesan terapi keluarga ke atas herotan kognitif pesalah remaja. Subjek kajian terdiri daripada 18 orang pesalah jenayah remaja yang menerima perintah bon berkelakuan baik berserta perintah tambahan bengkel interaktif sebagai kumpulan rawatan dan 18 orang pesalah remaja yang menerima perintah bon berkelakuan baik tanpa perintah tambahan bengkel interaktif sebagai kumpulan kawalan. Herotan kognitif diukur menggunakan soal selidik laporan kendiri Cognitive Distortion Scale (CDS). Subjek rawatan diberikan enam sesi terapi keluarga dalam jangka masa 2 - 3 bulan selama 50 ke 90 minit bagi setiap sesi. Ujian SPANOVA digunakan untuk mengukur kesan terapi keluarga ke atas pesalah remaja. Hasil kajian menunjukkan terapi keluarga berkesan secara signifikan untuk mengurangkan herotan kognitif pesalah remaja.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  5. Amirah Audadi Madzen, Lam KC
    Sains Malaysiana, 2017;46:421-428.
    Fenologi tumbuhan menggambarkan fasa kitaran hidup atau aktiviti tumbuhan dan adalah penting untuk memahami
    interaksinya dengan iklim. Kajian dilakukan untuk mengenal pasti respons fenologi tumbuhan dan metrik fenologi
    hutan dipterokarpa, kelapa sawit dan pokok getah menggunakan data indeks tumbuhan Enhanced Vegetation Index
    (EVI) daripada MODIS-Aqua (produk MYD13Q1) dan purata hujan bulanan sepanjang tahun 2007 dan 2009 di negeri
    Johor. Pola hujan pada tahun 2007 menunjukkan taburan hujan normal, manakala tahun 2009 mengalami kekurangan
    hujan sepanjang tempoh sebelas tahun (2000-2010). Hasil mendapati tren EVI hutan dipterokarpa lebih bervariasi pada
    2009 dengan nilai EVI antara 0.39-0.64 berbanding tren pada 2007 yang tekal dengan nilai EVI antara 0.33-0.57. Tren
    fenologi kelapa sawit pada 2007 lebih kerap mengalami turun naik berbanding pada 2009, masing-masing dengan EVI
    antara 0.45-0.71 dan 0.5-0.74. Corak fenologi pokok getah pada kedua-dua tahun kajian adalah sama dan julat EVI
    pada 2009 adalah lebih kecil berbanding 2007, masing-masing dengan EVI antara 0.39-0.62 dan 0.30-0.73. Pengaruh
    masa susulan ke atas tahap kehijauan tumbuhan telah dikesan, khususnya selepas peristiwa hujan lebat dalam dua
    tahun tersebut dan sedikit sebanyak mempengaruhi nilai korelasi antara pemboleh ubah purata hujan bulanan dengan
    EVI tumbuh-tumbuhan. Permulaan dan pengakhiran musim pertumbuhan hutan dipterokarpa bagi kedua-dua tahun
    berlaku dalam bulan yang sama, iaitu Februari (permulaan musim) dan Disember (pengakhiran musim). Tidak wujud
    perbezaan yang ketara antara panjang musim pertumbuhan kelapa sawit bagi kedua-dua tahun, iaitu hanya 32 hari
    lebih panjang pada 2007 berbanding 2009. Musim pertumbuhan pokok getah pula adalah lebih panjang pada 2007 dan
    lebih singkat pada 2009, masing-masing 176 hari dan 113 hari.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  6. Tursun M, Kumar CS, Bilge M, Rhyman L, Fun HK, Parlak C, et al.
    PMID: 25829021 DOI: 10.1016/j.saa.2015.03.022
    Molecular structure and properties of 2-fluoro-4-bromobenzaldehyde (FBB, C7H4BrFO) was experimentally investigated by X-ray diffraction technique and vibrational spectroscopy. Experimental results on the molecular structure of FBB were supported with computational studies using the density functional theory, with the Becke-3-Lee-Yang-Parr functional and the 6-311+G(3df,p) basis set. Molecular dimer formed by the intermolecular hydrogen bonding was investigated. Potential energy distribution analysis of normal modes was performed to identify characteristic frequencies. FBB crystallizes in orthorhombic space group P2(1)2(1)2(1) with the O-trans conformation. In order to investigate halogen effect, the chloro- (CBB) and bromo- (BBB) analogs of FBB have also been studied theoretically. It is observed that all compounds prefer the stable O-trans conformation. Although the free energy difference between the O-cis and O-trans conformers is less than 2.5 kcal/mol, the free energy rotational barrier is at least 7.4 kcal/mol. There is a good agreement between the experimentally determined structural parameters, and vibrational frequencies of FBB and those predicted theoretically.
    Matched MeSH terms: Hydrocarbons, Chlorinated/chemistry*
  7. Elia-Amira NMR, Chen CD, Lau KW, Lee HL, Low VL, Norma-Rashid Y, et al.
    J. Econ. Entomol., 2018 09 26;111(5):2488-2492.
    PMID: 29982497 DOI: 10.1093/jee/toy184
    The present study aims to investigate the susceptibility status of Aedes albopictus (Skuse) collected from residential areas in Sabah, Malaysia towards eight WHO-recommended dosages of larvicides representing the classes of organophosphates and organochlorines. Field and reference strains of Ae. albopictus larvae were bioassayed in accordance to WHO standard methods using diagnostic dosages of bromophos, malathion, fenthion, fenitrothion, temephos, chlorpyrifos, dichlorodiphenyltrichloroethane (DDT), and dieldrin. The results revealed that Ae. albopictus was resistant (mortality < 90%) towards malathion, temephos, and DDT. In addition, most of the Ae. albopictus strains exhibited a wide range of susceptibilities against bromophos, with mortality ranged from 49.33 to 93.33%. On the contrary, only dieldrin was able to induce 100% mortality against all strains of Ae. albopictus. Tolerance to fenitrothion, fenthion, and chlorpyrifos, with mortality ranging from 81.33 to 97.33%, was also observed in this study.
    Matched MeSH terms: Hydrocarbons, Chlorinated*
  8. Noordeyana T, Rozmi I, Muhammad Ajib Abdul R, Mohd Nasir S, Nurul Shafini S, Norhayati I, et al.
    Jurnal Psikologi Malaysia, 2018;32:94-103.
    Artikel ini bertujuan mengkaji keberkesanan program SHIELDS daripada perspektif pelajar dan urusetia yang telah turut terlibat. Program SHIELDS adalah satu bentuk program campbased yang diperkenalkan hasil kerjasama antara Kementerian Pendidikan dan Pihak Agensi Anti Dadah Kebangsaan (AADK). Nama SHEILDS ini adalah akronim yang bermaksud Sayangi Hidup, Elak Derita Selamanya. Sehubungan itu, program ini bertujuan meningkatkan kesedaran dan mengupayakan ketahanan diri murid (lingkungan umur 13 hingga 18 tahun) yang dikenalpasti berisiko dalam penyalahgunaan dadah. Kajian kuantitatif ini melibatkan dua fasa iaitu fasa pertama adalah mengedarkan soal selidik sebelum dan selepas program SHIELDS dijalankan. Manakala, fasa kedua pula adalah sesi follow up selepas 3 bulan terhadap 50 pelajar yang telah terlibat dengan program SHIELDS terlebih dahulu. Hasil kajian menunjukkan secara keseluruhan perspektif pelajar seramai 559 orang yang terlibat dengan program SHIELDS ini adalah baik dengan min=4.48. Kesimpulannya, dapatan ini menunjukkan bahawa program SHIELDS ini sewajarnya diteruskan dengan beberapa penambahbaikan untuk kelangsungan program dan kebaikan semua pihak yang terlibat.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  9. Mohd. Suhaimi Ahmad, Muhammad Ridwan Fahmi, Mustaqqim Abdul Rahim, Naimah Ibrahim
    Sains Malaysiana, 2016;45:1857-1867.
    Suatu kajian untuk menilai kesan gabungan aktiviti guna tanah dan perubahan musim terhadap kualiti sumber air telah dijalankan di Terusan Utara, Kedah. Kajian ini dijalankan di lima stesen terpilih selama 12 bulan berdasarkan Indeks Kualiti Air (WQI) dan Piawaian Interim Kualiti Air Kebangsaan (INWQS). Kajian mendapati kualiti air di Terusan Utara berada pada Kelas III dan berlaku peningkatan kualiti air dari hulu ke hilir. Hampir semua stesen berpotensi sebagai punca pencemaran berdasarkan aktiviti guna tanah terutamanya di Pelubang, Jitra serta Tunjang. Kajian menunjukkan terdapat perbezaan yang signifikan ketika perubahan musim pada DO, TSS serta BOD, namun tidak pada ammonia, pH dan COD. Secara amnya, kombinasi aktiviti guna tanah dan perubahan musim boleh mempengaruhi atau memberi kesan terhadap kualiti sumber air. Oleh itu, tindakan segera perlu dilakukan untuk mengawal punca pencemaran bagi memastikan kualiti sumber air di Terusan Utara kekal terpelihara.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  10. Arai T
    Mar. Pollut. Bull., 2014 Mar 15;80(1-2):186-93.
    PMID: 24461693 DOI: 10.1016/j.marpolbul.2014.01.011
    Members of the catadromous eel live in various fresh, brackish and marine habitats. Therefore, these eels can accumulate organic pollutants and are a suitable bioindicator species for determining the levels of organic contaminants within different water bodies. The ecological risk for organochlorine compounds (OCs) in Anguilla japonica with various migration patterns, such as freshwater, estuarine and marine residences, was examined to understand the specific accumulation patterns. The concentrations of HCB, ∑HCHs, ∑CHLs and ∑DDTs in the silver stage (maturing) eel were significantly higher than those in the yellow stage (immature) eel, in accordance with the higher lipid contents in the former versus the latter. The OC accumulations were clearly different among migratory types in the eel. The ecological risk of OCs increased as the freshwater residence period in the eel lengthened. The migratory histories and the lipid contents directly affected the OC accumulation in the catadromous eel species.
    Matched MeSH terms: Hydrocarbons, Chlorinated/metabolism*
  11. Leong KH, Tan LL, Mustafa AM
    Chemosphere, 2007 Jan;66(6):1153-9.
    PMID: 17027062
    In Malaysia, rivers are the main source of public water supplies. This study was conducted from 2002 to 2003 to determine the levels of selected organochlorine and organophosphate pesticides in the Selangor River in Malaysia. Surface water samples have been collected seasonally from nine sites along the river. A liquid-liquid extraction followed by gas chromatography-mass spectrometry technique was used to determine the trace levels of these pesticide residues. The organochlorine pesticides detected were lindane, heptachlor, endosulfan, dieldrin, endosulfan sulfate, o,p'-DDT, p,p'-DDT, o,p'-DDE and p,p'-DDE whereas for organophosphate pesticides, they were chlorpyrifos and diazinon. At the river upstream where a dam is located for public water supply, incidents of pesticide levels exceeding the European Economic Community Directive of water quality standards have occurred. Furthermore, the wetland ecosystems located at the downstream of the river which houses the fireflies community is being threatened by occasional pesticide levels above EPA limits for freshwater aquatic organisms. The occurrence of these residual pesticides in the Selangor River can be attributed to the intense agriculture and urban activity.
    Matched MeSH terms: Hydrocarbons, Chlorinated/analysis*
  12. Tan GH
    Analyst, 1992 Jul;117(7):1129-32.
    PMID: 1524230
    Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.
    Matched MeSH terms: Hydrocarbons, Chlorinated*
  13. Tan GH, Vijayaletchumy K
    Bull Environ Contam Toxicol, 1994 Sep;53(3):351-6.
    PMID: 7919710
    Matched MeSH terms: Hydrocarbons, Chlorinated*
  14. Wan Mohd Razi Idris, Sahibin Abdul Rahim, Mohd Talib Latif, Zulfahmi Ali Rahman, Tukimat Lihan, Low YC, et al.
    Kajian yang dijalankan ini bertujuan untuk menilai indeks kualiti air di sekitar kawasan lombong di Sungai Pelepah Kanan, Kota Tinggi, Johor. Sebanyak enam stesen pensampelan telah dipilih dari bahagian hulu ke hilir sungai ini untuk menilai indeks kualiti air di sepanjang sungai tersebut. Tiga replikasi sampel telah diambil daripada setiap stesen pensampelan. Pengambilan sampel dilakukan pada dua musim yang berbeza iaitu musim kering (Julai) dan musim hujan (Disember) 2007. Parameter in-situ yang ditentukan dalam kajian ini ialah suhu, pH, oksigen terlarut (DO) dan konduktiviti. Parameter ex-situ yang dianalisis dalam makmal ialah turbiditi air, jumlah pepejal terampai (TSS), keperluan oksigen biokimia (BOD), keperluan oksigen kimia (COD) dan ammonia nitrogen (NH3-N). Berdasarkan Piawaian Interim Kualiti Air Kebangsaan Malaysia (INWQS) hasil kajian yang diperolehi menunjukkan semua stesen pensampelan di Sungai Pelepah Kanan pada bulan Julai berada dalam kelas I kecuali oksigen terlarut dan pH berada dalam kelas II. Selain itu, hasil kajian pada bulan Disember juga menunjukkan semua parameter fiziko-kimia berada dalam kelas I-II kecuali pH berada dalam kelas III. Ujian korelasi menunjukkan terdapat hubungan bererti antara parameter-parameter fiziko-kimia yang di tertentukan. Analisis Indeks Kualiti Air (IKA) menunjukkan nilai purata IKA pada bulan Julai adalah 96.88 (kelas I) manakala pada bulan Disember telah merosot ke 84.03 (kelas II). Berdasarkan kepada nilai IKA dan perbandingan dengan INWQS, indeks kualiti air Sungai Pelepah Kanan adalah berada pada tahap yang bersih dan kurang mengalami pencemaran yang serius daripada aktiviti antropogenik mahupun pencemaran secara semula jadi.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  15. Adamu A, Abdul Wahab R, Aliyu F, Abdul Razak FI, Mienda BS, Shamsir MS, et al.
    J. Mol. Graph. Model., 2019 Nov;92:131-139.
    PMID: 31352207 DOI: 10.1016/j.jmgm.2019.07.012
    Dehalogenases continue to garner interest of the scientific community due to their potential applications in bioremediation of halogen-contaminated environment and in synthesis of various industrially relevant products. Example of such enzymes is DehL, an L-2-haloacid dehalogenase (EC 3.8.1.2) from Rhizobium sp. RC1 that catalyses the specific cleavage of halide ion from L-2-halocarboxylic acids to produce the corresponding D-2-hydroxycarboxylic acids. Recently, the catalytic residues of DehL have been identified and its catalytic mechanism has been fully elucidated. However, the enantiospecificity determinants of the enzyme remain unclear. This information alongside a well-defined catalytic mechanism are required for rational engineering of DehL for substrate enantiospecificity. Therefore, using quantum mechanics/molecular mechanics and molecular mechanics Poisson-Boltzmann surface area calculations, the current study theoretically investigated the molecular basis of DehL enantiospecificity. The study found that R51L mutation cancelled out the dehalogenation activity of DehL towards it natural substrate, L-2-chloropropionate. The M48R mutation, however introduced a new activity towards D-2-chloropropionate, conveying the possibility of inverting the enantiospecificity of DehL from L-to d-enantiomer with a minimum of two simultaneous mutations. The findings presented here will play important role in the rational design of DehL dehalogenase for improving substrate utility.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  16. Ahmad UK, Ujang Z, Woon CH, Indran S, Mian MN
    Water Sci. Technol., 2004;50(9):137-44.
    PMID: 15581005
    Land application of sludge as fertilizers is a way of disposal and recycling of sludge. However, public concern has arisen due to the fact that organic contaminants in sludge may ultimately enter the food chain. Hence the need arises to analyse the organic contaminants such as PAHs and OCPs in sludge. In this study, Soxhlet was utilised as the extraction method and the extracts subjected to extensive cleanup via either silica columns or solid phase extraction cartridges prior to analysis using gas chromatography or high performance liquid chromatography. Sludge samples were collected from the drying beds of oxidation ponds in three locations in South Johore. OCPs such as heptachlor, dieldrin and pp-DDT were detected in low amounts (52-159 mg/kg) whereas PAHs such as naphthalene, phenanthrene, fluoranthene and benzo(a)pyrene were detected in the range of 0.2-5.5 mg/kg dry mass. Subcritical water extraction (SWE) recovery studies of PAHs were also performed from spiked sludge samples. Although a recovery range of 41-68% was obtained using the SWE method, the results indicated the usefulness of the technique as an alternative to Soxhlet extraction for the analysis of PAHs in sludge samples.
    Matched MeSH terms: Hydrocarbons, Chlorinated/analysis*; Hydrocarbons, Chlorinated/isolation & purification
  17. Ramu K, Kajiwara N, Sudaryanto A, Isobe T, Takahashi S, Subramanian A, et al.
    Environ. Sci. Technol., 2007 Jul 01;41(13):4580-6.
    PMID: 17695900
    Mussel samples were used in this study to measure the levels of polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs) in the coastal waters of Asian countries like Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, the Philippines, and Vietnam. PBDEs were detected in all the samples analyzed, and the concentrations ranged from 0.66 to 440 ng/g lipid wt. Apparently higher concentrations of PBDEs were found in mussels from the coastal waters of Korea, Hong Kong, China, and the Philippines, which suggests that significant sources of these chemicals exist in and around this region. With regard to the composition of PBDE congeners, BDE-47, BDE-99, and BDE-100 were the dominant congeners in most of the samples. Among the OCs analyzed, concentrations of DDTs were the highest followed by PCBs > CHLs > HCHs > HCB. Total concentrations of DDTs, PCBs, CHLs, and HCHs in mussel samples ranged from 21 to 58 000, 3.8 to 2000, 0.93 to 900, and 0.90 to 230 ng/g lipid wt., respectively. High levels of DDTs were found in mussels from Hong Kong, Vietnam, and China; PCBs were found in Japan, Hong Kong, and industrialized/urbanized locations in Korea, Indonesia, the Philippines, and India; CHLs were found in Japan and Hong Kong; HCHs were found in India and China. These countries seem to play a role as probable emission sources of corresponding contaminants in Asia and, in turn, may influence their global distribution.
    Matched MeSH terms: Hydrocarbons, Chlorinated/analysis; Hydrocarbons, Chlorinated/metabolism*
  18. Sudi IY, Shamsir MS, Jamaluddin H, Wahab RA, Huyop F
    Biotechnol. Biotechnol. Equip., 2014 Sep 03;28(5):949-957.
    PMID: 26019583
    The D-2-haloacid dehalogenase of D-specific dehalogenase (DehD) from Rhizobium sp. RC1 catalyses the hydrolytic dehalogenation of D-haloalkanoic acids, inverting the substrate-product configuration and thereby forming the corresponding L-hydroxyalkanoic acids. Our investigations were focused on DehD mutants: R134A and Y135A. We examined the possible interactions between these mutants with haloalkanoic acids and characterized the key catalytic residues in the wild-type dehalogenase, to design dehalogenase enzyme(s) with improved potential for dehalogenation of a wider range of substrates. Three natural substrates of wild-type DehD, specifically, monochloroacetate, monobromoacetate and D,L-2,3-dichloropropionate, and eight other non-natural haloalkanoic acids substrates of DehD, namely, L-2-chloropropionate; L-2-bromopropionate; 2,2-dichloropropionate; dichloroacetate; dibromoacetate; trichloroacetate; tribromoacetate; and 3-chloropropionate, were docked into the active site of the DehD mutants R134A and Y135A, which produced altered catalytic functions. The mutants interacted strongly with substrates that wild-type DehD does not interact with or degrade. The interaction was particularly enhanced with 3-chloropropionate, in addition to monobromoacetate, monochloroacetate and D,L-2,3-dichloropropionate. In summary, DehD variants R134A and Y135A demonstrated increased propensity for binding haloalkanoic acid and were non-stereospecific towards halogenated substrates. The improved characteristics in these mutants suggest that their functionality could be further exploited and harnessed in bioremediations and biotechnological applications.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  19. Sudaryanto A, Kunisue T, Tanabe S, Niida M, Hashim H
    Arch. Environ. Contam. Toxicol., 2005 Oct;49(3):429-37.
    PMID: 16132420
    This study determined the concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and tris(4-chlorophenyl) methane (TCPMe) in human breast milk samples collected in 2003 from primipara mothers living in Penang, Malaysia. OCs were detected in all the samples analyzed with DDTs, hexachlorocyclohexane isomers (HCHs), and PCBs as the major contaminants followed by chlordane compounds (CHLs), hexachlorobenzene (HCB), and TCPMe. The residue levels of DDTs, HCHs, and CHLs were comparable to or higher than those in general populations of other countries, whereas PCBs and HCB were relatively low. In addition, dioxins and related compounds were also detected with a range of dioxin equivalent concentrations from 3.4 to 24 pg-TEQs/g lipid wt. Levels of toxic equivalents (TEQs) were slightly higher than those in other developing countries but still much lower than those of industrialized nations. One donor mother contained a high TEQs level, equal to the mean value in human breast milk from Japan, implying that some of the residents in Malaysia may be exposed to specific pollution sources of dioxins and related compounds. No association was observed between OCs concentrations and maternal characteristics, which might be related to a limited number of samples, narrow range of age of the donor mothers, and/or other external factors. The recently identified endocrine disrupter, TCPMe, was also detected in all human breast milk samples of this study. A significant positive correlation was observed between TCPMe and DDTs, suggesting that technical DDT might be a source of TCPMe in Malaysia. The present study provides a useful baseline for future studies on the accumulations of OCs in the general population of Malaysia.
    Matched MeSH terms: Hydrocarbons, Chlorinated/analysis*; Hydrocarbons, Chlorinated/metabolism; Hydrocarbons, Chlorinated/standards
  20. Ghani Z, Anuar A, Majid Z, Yoneda M
    Sains Malaysiana, 2017;46:2383-2392.
    This study describes the development of a multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT) at Sungai Sayong watershed. Based on the latest estimated DDT emission, the DDT concentrations in air, soil, water and sediment as well as the transfer processes were simulated under the equilibrium and steady-state assumption. Model predictions suggested that soil and sediment was the dominant sink of DDT. The results showed that the model predicted was generally good agreement with field data. Compared with degradation reaction, advection outflow was more important processes occurred in the model. Sensitivities of the model estimates to input parameters were tested. The result showed that vapour pressure (Ps) and organic carbon water partition coefficient (KOC) were the most influential parameters for the model output. The model output-concentrations of DDT in multimedia environment is very important as it can be used in future for human exposure and risk assessment of organochlorine pesticides (OCPs) at Sungai Sayong Basin.
    Matched MeSH terms: Hydrocarbons, Chlorinated
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