Displaying all 17 publications

  1. Halimah M, Tan YA, Ismail BS
    J Environ Sci Health B, 2004;39(5-6):765-77.
    PMID: 15620085
    Four methods were developed for the analysis of fluroxypyr in soil samples from oil palm plantations. The first method involved the extraction of the herbicide with 0.05 M NaOH in methanol followed by purification using acid base partition. The concentrated material was subjected to derivatization and then cleaning process using a florisil column and finally analyzed by gas chromatography (GC) equipped with electron capture detector (ECD). By this method, the recovery of fluroxypyr from the spiked soil ranged from 70 to 104% with the minimum detection limit at 5 microg/kg. The second method involved solid liquid extraction of fluroxypyr using a horizontal shaker followed by quantification using high performance liquid chromatography (HPLC) equipped with UV detector. The recovery of fluroxypyr using this method, ranged from 80 to 120% when the soil was spiked with fluroxypyr at 0.1-0.2 microg/g soil. In the third method, the recovery of fluroxypyr was determined by solid liquid extraction using an ultrasonic bath. The recovery of fluroxypyr at spiking levels of 4-50 microg/L ranged from 88 to 98% with relative standard deviations of 3.0-5.8% with a minimum detection limit of 4 microg/kg. In the fourth method, fluroxypyr was extracted using the solid liquid extraction method followed by the cleaning up step with OASIS HLB (polyvinyl dibenzene). The recovery of fluroxypyr was between 91 and 95% with relative standard deviations of 4.2-6.2%, respectively. The limit of detection in method 4 was further improved to 1 pg/kg. When the weight of soil used was increased 4 fold, the recovery of fluroxypyr at spiking level of 1-50 microg/kg ranged from 82-107% with relative standard deviations of 0.5-4.7%.
  2. Sundram K, Sambanthamurthi R, Tan YA
    Asia Pac J Clin Nutr, 2003;12(3):355-62.
    PMID: 14506001
    The palm fruit (Elaies guineensis) yields palm oil, a palmitic-oleic rich semi solid fat and the fat-soluble minor components, vitamin E (tocopherols, tocotrienols), carotenoids and phytosterols. A recent innovation has led to the recovery and concentration of water-soluble antioxidants from palm oil milling waste, characterized by its high content of phenolic acids and flavonoids. These natural ingredients pose both challenges and opportunities for the food and nutraceutical industries. Palm oil's rich content of saturated and monounsaturated fatty acids has actually been turned into an asset in view of current dietary recommendations aimed at zero trans content in solid fats such as margarine, shortenings and frying fats. Using palm oil in combination with other oils and fats facilitates the development of a new generation of fat products that can be tailored to meet most current dietary recommendations. The wide range of natural palm oil fractions, differing in their physico-chemical characteristics, the most notable of which is the carotenoid-rich red palm oil further assists this. Palm vitamin E (30% tocopherols, 70% tocotrienols) has been extensively researched for its nutritional and health properties, including antioxidant activities, cholesterol lowering, anti-cancer effects and protection against atherosclerosis. These are attributed largely to its tocotrienol content. A relatively new output from the oil palm fruit is the water-soluble phenolic-flavonoid-rich antioxidant complex. This has potent antioxidant properties coupled with beneficial effects against skin, breast and other cancers. Enabled by its water solubility, this is currently being tested for use as nutraceuticals and in cosmetics with potential benefits against skin aging. A further challenge would be to package all these palm ingredients into a single functional food for better nutrition and health.
  3. Halimah M, Tan YA, Aini K, Ismail BS
    J Environ Sci Health B, 2003 Jul;38(4):429-40.
    PMID: 12856925
    Improved methods for extraction and clean up of fluroxypyr residue in water have been established. Two methods of fluroxypyr extraction were used, namely, Direct Measurement of fluroxypyr and Concentration of fluroxypyr onto A Solid Phase Extraction (SPE) Adsorbent, followed by elution with solvent before determination of fluroxypyr. The recovery for Direct Measurement of fluroxypyr in water containing 8-100 microg L(-1), ranged from 86 to 110% with relative standard deviation of 0.7 to 2.15%. For the second method, three types of SPE were used, viz. C18, C18 end-capped and polyvinyl dibenzene (ISOLUTE ENV+). The procedure involved concentrating the analyte from fluroxypyr-spiked water at pH 3, followed by elution of the analyte with 4 mL of acentonitrile. The recovery of fluroxypyr from the spiked sample at 1 to 50 microg L(-1) after eluting through either C18 or C18 end-capped ranged from 40-64% (with relative standard deviation of 0.7 to 2.15) and 41-65% (with standard deviation of 1.52 to 11.9). The use of ISOLUTE ENV+, gave better results than the C18, C18 end-capped or the Direct Measurement Methods. The recovery and standard deviation of fluroxypyr from spiked water using ISOLUTE ENV+ ranged from 91-102% and 2.5 to 5.3, respectively.
  4. Cheo SW, Low QJ, Tan YA, Chia YK
    Clin Med (Lond), 2020 05;20(3):e20-e21.
    PMID: 32414735 DOI: 10.7861/clinmed.2020-0019
    Neuromyelitis optica spectrum disorder (NMOSD) is a rare inflammatory disorder of the nervous system which can be potentially debilitating. Its prevalence is estimated to be around 0.5-10 per 100,000 population with predilection towards Asians and females. It can be diagnosed based on core clinical characteristics, serum aquaporin antibodies and neuroimaging features. It is important to pick up the diagnosis of NMOSD as the treatment is different from other demyelinating disease. Here, we illustrate a case of NMOSD presented with intractable vomiting.
  5. Cheo SW, Low QJ, Tan YA, Chia YK
    QJM, 2020 Feb 01;113(2):131-132.
    PMID: 31168610 DOI: 10.1093/qjmed/hcz137
  6. Cheo SW, Mohd Zamin H, Low QJ, Tan YA, Chia YK
    Med J Malaysia, 2020 11;75(6):745-747.
    PMID: 33219190
    Stroke is a debilitating disease as it carries significant morbidity especially when it affects the younger population. There are various etiologies of young stroke, namely arterial dissection, cardioembolism, thrombophilia, inherited genetic disorder and vasculitis. Young patient with stroke should undergo complete evaluation to identify the underlying etiology in order to prevent recurrence of stroke. Here, we would like to illustrate a case of Takayasu arteritis presenting as young stroke in a 17-years-old lady with no known medical illness.
  7. Khoo TT, Cheo SW, Low QJ, Tan YA, Wong LLL
    Med J Malaysia, 2021 Jan;76(1):118-120.
    PMID: 33510123
    Hodgkin lymphoma is a form of malignant lymphoid neoplasm. It can have various clinical presentations such as prolonged fever, night sweats, weight loss and asymptomatic lymphadenopathy. It has a distinct fever pattern known as Pel Ebstein fever. However, in some instances, its clinical presentation can mimic some tropical infections. Here, we present a case of primary splenic lymphoma masquerading as splenic abscess in a 53-yearold man with underlying dyslipidemia.
  8. Tan YA, Ng KC, Cheo SW, Low QJ, Chia YK
    QJM, 2020 07 01;113(7):485-487.
    PMID: 32053172 DOI: 10.1093/qjmed/hcaa025
  9. Tan YA, Ng KC, Cheo SW, Khoo TT, Low QJ
    Clin Med (Lond), 2020 09;20(5):519-521.
    PMID: 32934050 DOI: 10.7861/clinmed.2020-0364
    Methaemoglobinaemia is an uncommon but potentially serious condition. It can be caused by congenital or acquired cause. Drug-induced methaemoglobinaemia is the commonest cause of acquired methaemoglobinaemia. The clinical signs and symptoms of methaemoglobinaemia include dyspnoea, desaturation, presence of saturation gap, headache, nausea and seizures depending on level of serum methaemoglobinaemia. We illustrate a case of dapsone-induced methaemoglobinaemia and its successful treatment by intravenous methylene blue.
  10. Cheo SW, Khoo TT, Tan YA, Yeoh WC, Low QJ
    Med J Malaysia, 2020 07;75(4):447-449.
    PMID: 32724015
    Malaria is a parasitic disease that is caused by the Plasmodium parasite. Worldwide, it remains a significant public health problem especially in the Africa region where it contributes to more than 90% of cases and malaria death. However, zoonotic (simian) Plasmodium knowlesi parasite is a widely prevalent cause of malaria in the South East Asian countries. It is known to cause severe human disease due to its 24hour erythrocytic cycles. Thus far, cases of severe falciparum malaria have been reported in asplenic patients. Here, we report a case of severe P.knowlesi malaria in a 51-year-old man who is a postsplenectomy patient.
  11. Cheo SW, Ong SAM, Low QJ, Tan YA, Chia YK
    QJM, 2020 Oct 01;113(10):743-746.
    PMID: 32240316 DOI: 10.1093/qjmed/hcaa107
  12. Cheo SW, Ahmad Akbar RZ, Abd Rahman F, Abdul Rashid WNF', Tan YA, Low QJ
    QJM, 2020 Nov 01;113(11):809-812.
    PMID: 32275748 DOI: 10.1093/qjmed/hcaa122
  13. Fairus S, Leow SS, Mohamed IN, Tan YA, Sundram K, Sambanthamurthi R
    Sci Rep, 2018 05 29;8(1):8217.
    PMID: 29844318 DOI: 10.1038/s41598-018-26384-7
    Plant phenolics are being increasingly consumed globally with limited scientific and clinical evidence pertaining to safety and efficacy. The oil palm fruit contains a cocktail of phenolics, and palm oil production results in high volumes of aqueous by-products enriched in phenolics and bioactives. Several lines of evidence from in vitro and in vivo animal studies confirmed that the aqueous extract enriched in phenolics and other bioactives collectively known as oil palm phenolics (OPP) is safe and has potent bioactivity. A phase one clinical trial was conducted to evaluate the safety and effects of OPP in healthy volunteers. In this single-blind trial, 25 healthy human volunteers were supplemented with 450 mg gallic acid equivalent (GAE)/day of OPP or control treatments for a 60-day period. Fasting blood and urine samples were collected at days 1, 30 and 60. Medical examination was performed during these trial interventions. All clinical biochemistry profiles observed throughout the control and OPP treatment period were in the normal range with no major adverse effect (AE) or serious adverse effect (SAE) observed. Additionally, OPP supplementation resulted in improvement of total cholesterol and LDL-C levels, compared to the control treatment. The outcomes support our previous observations that OPP is safe and may have a protective role in reducing cholesterol levels.
  14. Tan YA, Ng KC, Cheo SW, Low QJ, Chia YK
    QJM, 2020 07 01;113(7):517-518.
    PMID: 32191336 DOI: 10.1093/qjmed/hcaa099
  15. Low QJ, Hon SA, Garry Siow PW, Lim TH, Lee RA, Tan YA, et al.
    QJM, 2020 Oct 01;113(10):753-754.
    PMID: 31995198 DOI: 10.1093/qjmed/hcaa014
  16. Weinberg RP, Koledova VV, Shin H, Park JH, Tan YA, Sinskey AJ, et al.
    Int J Alzheimers Dis, 2018;2018:7608038.
    PMID: 29666700 DOI: 10.1155/2018/7608038
    Alzheimer's disease is a severe neurodegenerative disease characterized by the aggregation of amyloid-β peptide (Aβ) into toxic oligomers which activate microglia and astrocytes causing acute neuroinflammation. Multiple studies show that the soluble oligomers of Aβ42 are neurotoxic and proinflammatory, whereas the monomers and insoluble fibrils are relatively nontoxic. We show that Aβ42 aggregation is inhibited in vitro by oil palm phenolics (OPP), an aqueous extract from the oil palm tree (Elaeis guineensis). The data shows that OPP inhibits stacking of β-pleated sheets, which is essential for oligomerization. We demonstrate the inhibition of Aβ42 aggregation by (1) mass spectrometry; (2) Congo Red dye binding; (3) 2D-IR spectroscopy; (4) dynamic light scattering; (5) transmission electron microscopy; and (6) transgenic yeast rescue assay. In the yeast rescue assay, OPP significantly reduces the cytotoxicity of aggregating neuropeptides in yeast genetically engineered to overexpress these peptides. The data shows that OPP inhibits (1) the aggregation of Aβ into oligomers; (2) stacking of β-pleated sheets; and (3) fibrillar growth and coalescence. These inhibitory effects prevent the formation of neurotoxic oligomers and hold potential as a means to reduce neuroinflammation and neuronal death and thereby may play some role in the prevention or treatment of Alzheimer's disease.
  17. Klionsky DJ, Abdel-Aziz AK, Abdelfatah S, Abdellatif M, Abdoli A, Abel S, et al.
    Autophagy, 2021 Jan;17(1):1-382.
    PMID: 33634751 DOI: 10.1080/15548627.2020.1797280
    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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