Displaying publications 1 - 20 of 51 in total

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  1. Fulltext Rare cause of Horner's syndrome: pseudoaneurysm of right subclavian artery in an intravenous drug user
    Lee SK, Zainal A
    Med J Malaysia, 2004 Mar;59(1):115-7.
    PMID: 15535347
    Pseudoaneurysms of the subclavian artery are extremely rare lesions despite the overall increase in the frequency of septic pseudoaneurysms caused by illicit parenteral drug abuse. A case of subclavian artery pseudoaneurysm presenting with Horner's syndrome in an intravenous drug user is discussed.
  2. A survey of gross alpha and gross beta activity in soil samples in Kinta District, Perak, Malaysia
    Lee SK, Wagiran H, Ramli AT
    Radiat Prot Dosimetry, 2014 Dec;162(3):345-50.
    PMID: 24214911 DOI: 10.1093/rpd/nct273
    The objective of this study was to determine the gross alpha and gross beta activity concentrations from the different soil types found in the Kinta District, Perak, Malaysia. A total of 128 soil samples were collected and their dose rates were measured 1 m above the ground. Gross alpha and gross beta activity measurements were carried out using gas flow proportional counter, Tennelec Series 5 LB5500 Automatic Low Background Counting System. The alpha activity concentration ranged from 15 to 9634 Bq kg(-1) with a mean value of 1558±121 Bq kg(-1). The beta activity concentration ranged from 142 to 6173 Bq kg(-1) with a mean value of 1112±32 Bq kg(-1). High alpha and beta activity concentrations are from the same soil type. The results of the analysis show a strong correlation between the gross alpha activity concentration and dose rate (R = 0.92). The data obtained can be used as a database for each soil type.
  3. Fulltext Coeliac artery thrombosis: an uncommon cause of an acute abdomen
    Saravana K, Zainal AA, Lee SK
    Med J Malaysia, 2011 Aug;66(3):273-5.
    PMID: 22111460 MyJurnal
    Coeliac artery thrombosis with ischaemia is a rare condition, which usually presents with severe peptic ulcer disease symptoms. It is usually associated with risk factors for thrombosis or embolism. The manifestation is rare because of large number of collaterals between the coeliac and superior mesentery artery. Early detection and intervention is required to prevent the progression of its complications that includes gastric ischaemic necrosis.
  4. Melioidosis and the vascular surgeon: Hospital Kuala Lumpur experience
    Azizi ZA, Yahya M, Lee SK
    Asian J Surg, 2005 Oct;28(4):309-11.
    PMID: 16234087
    Bacterial arteritis is relatively uncommon and management of this condition, which carries high morbidity and mortality, is difficult and time-consuming. Common organisms implicated include Salmonella and Staphylococcus. Arteritis as a result of infection by Burkholderia pseudomallei (formerly Pseudomonas pseudomallei) has been rarely reported in the English literature. This organism, which is endemic in our part of the world, is well known to cause a wide spectrum of septic conditions. A review of cases managed at Hospital Kuala Lumpur revealed that bacterial arteritis due to melioidosis is not such a rare entity. We share our experience in the management of this condition using three cases as examples.
  5. Fulltext Experiments with banana trunk juice as a neuromuscular blocker
    Lee SK, Ng LL, Lee SI
    Med J Malaysia, 1980 Jun;34(4):423-5.
    PMID: 7219276
    The juice of the banana trunk produces a nondepolarising neuromuscular block. Oxygenation of
    the extract enhances its potency. Reversal with anticholinesterase is transient. Partial reversals in isolated preparations indicate there could be both specific and non-specific binding which could account for blockade after washing. It could be specifically bound to ACh receptors in an irreversible way. Its action appears similar to that of alpha-BuTX from the venom of the banded krait. Purification of the extract and subsequent investigations will support present findings and present the characteristics fully.
  6. Recurrent respiratory tract infection due to isolated absence of IgA: report of a case
    Chia BL, Chew CH, Lee SK
    Med J Malaya, 1970 Mar;24(3):215-7.
    PMID: 4193671
  7. Topoisomerase I inhibition and DNA cleavage by zinc, copper, and nickel derivatives of 2-[2-bromoethyliminomethyl]-4-[ethoxymethyl]phenol complexes exhibiting anti-proliferation and anti-metastasis activity
    Lee SK, Tan KW, Ng SW
    J Inorg Biochem, 2016 06;159:14-21.
    PMID: 26901628 DOI: 10.1016/j.jinorgbio.2016.02.010
    Three transition metal derivatives (Zn, Cu, and Ni) of 2-[2-bromoethyliminomethyl]-4-[ethoxymethyl]phenol (L) were synthesized by the reaction of the metal salts with the Schiff base ligand in one pot. In the crystal structure of [Zn(L)Br], the Schiff base ligand binds to the metal center through its phenolate oxygen and imine nitrogen, and adopts a distorted tetrahedral geometry. These compounds were found to inhibit topoisomerase I (topo I) activity, induce DNA cleavage and show DNA binding activity. Moreover, these compounds were found to be cytotoxic towards several cancer cell lines (A2780, MCF-7, HT29, HepG2, A549, PC3, LNCaP) and prevent metastasis of PC3. Collectively, Cu(II) complex 2 shows superior activity relative to its Zn(II) and Ni(II) analogs.
  8. [3 Malayan trematodes]
    Rohde K, Lee SK, Lim HW
    Ann Parasitol Hum Comp, 1968 Jan-Feb;43(1):33-43.
    PMID: 4192885
  9. Inequalities on an extended Bessel function
    Ali RM, Lee SK, Mondal SR
    J Inequal Appl, 2018;2018(1):66.
    PMID: 29606843 DOI: 10.1186/s13660-018-1656-4
    This paper studies an extended Bessel function of the form [Formula: see text] Representation formulations for [Formula: see text] are derived in terms of the parametersa,b, and p. An important consequence is the derivation of an [Formula: see text]-order differential equation satisfied by the function [Formula: see text]. Interesting functional inequalities are established, particularly for the case [Formula: see text], and [Formula: see text]. Monotonicity properties of [Formula: see text] are also studied for non-positive c. Log-concavity and log-convexity properties in terms of the parametersdandpare respectively investigated for the closely related function [Formula: see text] which leads to direct and reverse Turán-type inequalities.
  10. Measurement of ²³⁸U,²³²Th and ⁴⁰K in boreholes at Gosa and Lugbe, Abuja, north central Nigeria
    Maxwell O, Wagiran H, Ibrahim N, Lee SK, Sabri S
    Radiat Prot Dosimetry, 2013 Dec;157(2):271-7.
    PMID: 23754832 DOI: 10.1093/rpd/nct140
    The purpose of this project is to evaluate the suitability of different sites as locations for obtaining underground water for consumption. The analysis of ²³⁸U, ²³²Th and ⁴⁰K from rock samples from each layer of borehole at a depth of ∼50 m at Site A borehole, S3L1-S3L6 in Gosa and 40 m at Site B borehole, S4L1-S4L5 in Lugbe, Abuja, north central Nigeria is presented. The gamma-ray spectrometry was carried out using a high-purity germanium detector coupled to a computer-based high-resolution multichannel analyzer. The activity concentrations at Site A borehole for ²³⁸U have a mean value of 26 ± 3, ranging from 23 ± 2 to 30 ± 3 Bq kg⁻¹, ²³²Th a mean value of 63 ± 5, ranging from 48 ± 4 to 76 ± 6 Bq kg⁻¹ and ⁴⁰K a mean value of 573 ± 72, ranging from 437 ± 56 to 821 ± 60 Bq kg⁻¹. The activity concentrations at Site B borehole for ²³⁸U have a mean value of 20 ± 2, ranging from 16 ± 2 to 23 ± 2 Bq kg⁻¹, ²³²Th a mean value of 46 ± 4, ranging from 43 ± 4 to 49 ± 4 Bq kg⁻¹, ⁴⁰K a mean value of 915 ± 116 and ranging from 817 ± 103 Bq kg⁻¹ to 1011 ± 128 Bq kg⁻¹. It is noted that the higher activity concentrations of ²³²Th and ²³⁸U are found in Site A at Gosa. Site B has lower radioactivity, and it is recommended that both sites are suitable for underground water consumption.
  11. Applying the least squares method for the titrimetric determination of the concentration of VFA
    Lee SK, Yeoh HK, Chua AS, Ngoh GC
    Water Sci Technol, 2012;66(3):620-6.
    PMID: 22744694 DOI: 10.2166/wst.2012.216
    The titrimetric method is used for on-site measurement of the concentration of volatile fatty acids (VFAs) in anaerobic treatment. In current practice, specific and interpolated pH-volume data points are used to obtain the concentration of VFA by solving simultaneous equations iteratively to convergence (denoted as SEq). Here, the least squares method (LSM) is introduced as an elegant alternative. Known concentrations of VFA (acetic acid and/or propionic acid) ranging from to 200 to 1,000 mg/L were determined using SEq and LSM. Using standard numbers of data points, SEq gave more accurate results compared with LSM. However, results favoured LSM when all data points in the range were included without any interpolation. For model refinement, unit monovalent activity coefficient (f(m) = 1) was found reasonable and arithmetic averages of dissociation constants and molecular weight of 80 mol% acetic acid were recommended in the model for VFA determination of mixtures. An accurate result was obtained with a mixture containing more VFA (butyric acid and valeric acid). In a typical VFA measurement of real anaerobic effluent, a satisfactory result with an error of 14% was achieved. LSM appears to be a promising mathematical model solver for determination of concentration of VFA in the titrimetric method. Validation of LSM in the presence of other electrolytes deserves further exploration.
  12. Specimen shrinkage and its influence on margin assessment in breast cancer
    Yeap BH, Muniandy S, Lee SK, Sabaratnam S, Singh M
    Asian J Surg, 2007 Jul;30(3):183-7.
    PMID: 17638637
    The determination of tumour-free margin in breast cancer is crucial in deciding subsequent patient management. To exemplify the phenomenon of margin contraction during specimen preparation for histopathological analysis, we quantified the shrinkage of breast specimens as a result of formalin fixation.
  13. A validation study of the Siriraj Stroke Score
    Kan CH, Lee SK, Low CS, Velusamy SS, Cheong I
    Int J Clin Pract, 2000 Dec;54(10):645-6.
    PMID: 11221275
    A cross-sectional study was conducted on 160 Malaysian patients to validate the usefulness of the Siriraj Stroke Score (SSS) for differentiating intracerebral haemorrhage and infarction following acute strokes. Our results indicate that the score lacks sensitivity and specificity. It should thus not be used in epidemiological studies to determine stroke types in a community. More importantly, in the absence of information from neuroimaging of the brain, it cannot be used safely by physicians to assess the need or otherwise of thrombolytic and/or anticoagulant therapy after an acute stroke.
  14. Glutathione system in young spontaneously hypertensive rats
    Lee SK, Arunkumar S, Sirajudeen KN, Singh HJ
    J Physiol Biochem, 2010 Dec;66(4):321-7.
    PMID: 20680541 DOI: 10.1007/s13105-010-0038-2
    Glutathione (GSH) forms a part of the antioxidant system that plays a vital role in preventing oxidative stress, and an imbalance in the oxidant/antioxidant system has been linked to the pathogenesis of hypertension. The aim of this study was to investigate the status of the GSH system in the kidney of spontaneously hypertensive rats (SHR). Components of the GSH system, including glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), and total GSH content, were measured in the kidneys of 4, 6, 8, 12, and 16 weeks old SHR and Wistar-Kyoto (WKY) rats. Systolic blood pressure of SHR was significantly higher from the age of 6 weeks onwards compared with age-matched WKY rats. GPx activity in the SHR was significantly lower from the age of 8 weeks onwards when compared to that in age-matched WKY rats. No significant differences were evident in the GPx-1 protein abundance, and its relative mRNA levels, GR, GST activity, and total GSH content between SHR and age-matched WKY rats. The lower GPx activity suggests of an impairment of the GSH system in the SHR, which might be due to an abnormality in its protein rather than non-availability of a cofactor. Its role in the development of hypertension in SHR however remains unclear.
  15. Effect of cross-fostering on renal anti-oxidant/oxidant status and development of hypertension in spontaneously hypertensive rats
    Lee SK, Sirajudeen KN, Sundaram A, Zakaria R, Singh HJ
    Clin Exp Pharmacol Physiol, 2011 Dec;38(12):854-9.
    PMID: 21973174 DOI: 10.1111/j.1440-1681.2011.05624.x
    1. The hypotensive effect of cross-fostering in spontaneously hypertensive rats (SHR) is thought to involve adjustments in renal function. However, its association with renal anti-oxidant/oxidant balance during cross-fostering is not known. 2. The present study examined the effect of cross-fostering and in-fostering of 1-day-old offspring between SHR and Wistar-Kyoto (WKY) dams on renal anti-oxidant/oxidant status and systolic blood pressure (SBP). Renal anti-oxidant/oxidant status and SBP were determined in the offspring from 4-16 weeks of age. 3. Cross-fostered SHR had significantly lower SBP than in-fostered SHR at 6, 8 and 12 weeks, but not at 16 weeks (127 ± 1 vs 144 ± 2, 138 ± 1 vs 160 ± 1, 174 ± 2 vs 184 ± 2 and 199 ± 2 vs 194 ± 3 mmHg at 6, 8, 12 and 16 weeks, respectively). No differences in SBP were evident between cross-fostered and in-fostered WKY rats. There were no significant differences in levels of thiobarbituric acid-reactive substances (TBARS), protein carbonyl and total anti-oxidant status (TAS) or superoxide dismutase, catalase, glutathione peroxidase (GPx), glutathione S-transferase and glutathione reductase activity between cross-fostered and in-fostered SHR or WKY offspring. However, compared with WKY rats, catalase activity was higher at 6 and 16 weeks, TAS was higher at 16 weeks and GPx activity and TBARS were lower at 16 weeks in SHR. 4. It appears that cross-fostering of SHR offspring to WKY dams during the early postnatal period causes a transient delay in the rise in blood pressure in SHR and that this does not involve the renal anti-oxidant/oxidant system.
  16. Oral epigallocatechin gallate reduces intestinal nadolol absorption via modulation of Oatp1a5 and Oct1 transcriptional levels in spontaneously hypertensive rats
    Tan HJ, Ling WC, Chua AL, Lee SK
    Phytomedicine, 2021 Sep;90:153623.
    PMID: 34303263 DOI: 10.1016/j.phymed.2021.153623
    BACKGROUND: Concurrent use of epigallocatechin-3-gallate (EGCG) and medication may lead to botanical-drug interactions, subsequently therapeutic failure or drug toxicity. It has been reported that EGCG reduces plasma nadolol bioavailability in normotensive models. Nevertheless, evidence on the effects of EGCG on hypertensive model, and the possible underlying mechanism have not been elucidated.

    OBJECTIVES: This study aims (i) to investigate the effects of EGCG on nadolol pharmacokinetics (maximum plasma concentration, time to achieve maximum concentration, area under the time-plasma concentration curve, plasma half-life and total clearance) and subsequently its impact on blood pressure control; and (ii) to identify transcriptional regulatory roles of EGCG on the nadolol intestinal and hepatic drug-transporters in SHR.

    METHODS: Male SHR were pre-treated with a daily dose of EGCG (10 mg/kg body weight, i.g.) for 13 days. On day-14, a single dose of nadolol (10 mg/kg body weight) was given to the rats 30 min after the last dose of EGCG administration. Systolic blood pressure (SBP) was measured at 6-h and 22-h post-nadolol administration. Plasma and urinary nadolol concentrations were quantified using high-performance liquid chromatography, and pharmacokinetic parameters were analyzed by using non-compartmental analysis. Hepatic and ileal Oatp1a5, P-gp, and Oct1 mRNA expressions were determined by real-time PCR.

    RESULTS: SBP of SHR pre-treated with EGCG and received nadolol was significantly higher than those which were not pre-treated with EGCG but received nadolol. Pre-treatment of EGCG resulted in a marked reduction of plasma nadolol maximum concentration (Cmax) and area under the time-plasma concentration curve (AUC) by 53% and 51% compared to its control. The 14-day treatment with oral EGCG led to a significant downregulation of mRNA levels of ileal Oatp1a5, P-gp, and Oct1 genes by 4.03-, 8.01- and 4.03-fold; and hepatic P-gp, and Oct1 genes by 2.61- and 2.66-fold.

    CONCLUSION: These data concluded that exposure to EGCG could lead to reduced nadolol bioavailability and therefore, uncontrolled raised blood pressure and higher risks of cardiovascular events. Our data suggest that the reduced nadolol bioavailability is associated with the downregulation of ileal Oatp1a5 and Oct1 mRNA levels that subsequently lead to poor absorption of nadolol to the systemic circulation.

  17. Fulltext Safety and Efficacy of Dietary Epigallocatechin Gallate Supplementation in Attenuating Hypertension via Its Modulatory Activities on the Intrarenal Renin-Angiotensin System in Spontaneously Hypertensive Rats
    Parn KW, Ling WC, Chin JH, Lee SK
    Nutrients, 2022 Nov 01;14(21).
    PMID: 36364864 DOI: 10.3390/nu14214605
    This study aimed to identify the no-observed-adverse-effect level (NOAEL) of dietary epigallocatechin gallate (EGCG) supplementation and its possible antihypertensive and nutrigenomics effects in modulating intrarenal renin-angiotensin system (RAS) gene expression in spontaneously hypertensive rats (SHR). EGCG (50, 250, 500 or 1000 mg/kg b.w. i.g., once daily) was administered to SHR for 28 days. All the SHR survived with no signs of systemic toxicity. Increased alanine aminotransferase (ALT), aspartate aminotransferase (AST) and thiobarbituric acid reactive substances (TBARS) were evident in SHR supplemented with 500 and 1000 mg/kg b.w. but not in those supplemented with lower doses of EGCG. Subsequently, the NOAEL of EGCG was established at 250 mg/kg b.w., and the same protocol was replicated to assess its effects on blood pressure and renal RAS-related genes in SHR. The systolic blood pressure (SBP) of the EGCG group was consistently lower than the control group. The mRNA levels of cortical Agtr2 and Ace2 and medullary Agtr2, Ace and Mas1 were upregulated while medullary Ren was downregulated in EGCG group. Statistical analysis showed that SBP reduction was associated with the changes in medullary Agtr2, Ace, and Ren. Dietary EGCG supplementation exhibits antihypertensive and nutrigenomics effects through activation of intrarenal Ace and Agtr2 and suppression of Ren mediators, while a high dose of EGCG induced liver damage in SHR. In future clinical studies, liver damage biomarkers should be closely monitored to further establish the safety of the long-term use of EGCG.
  18. Fulltext Epigallocatechin gallate (EGCG) alleviates vascular dysfunction in angiotensin II-infused hypertensive mice by modulating oxidative stress and eNOS
    Mohd Sabri NA, Lee SK, Murugan DD, Ling WC
    Sci Rep, 2022 Oct 21;12(1):17633.
    PMID: 36271015 DOI: 10.1038/s41598-022-21107-5
    Epigallocatechin gallate (EGCG) has been shown to have antihypertensive activity. However, the role of epigallocatechin gallate (EGCG) in improving vascular function via modulation of endothelial nitric oxide synthase (eNOS) in hypertensive subjects is not well researched. Angiotensin II-infused hypertensive mice (8-10 weeks old) received EGCG (50 mg/kg/day) for 14 days via oral gavage. The arterial systolic blood pressure (SBP) was measured using the tail-cuff method every three days. At the end of the treatment, the vascular reactivity of the isolated aortae was studied using wire myographs. The level of nitric oxide (NO), cyclic guanosine monophosphate (cGMP) and tetrahydrobiopterine (BH4) were determined using assay kits while the presence of proteins (NOS, p-eNOS and NOx-2) were determined using by Western blotting. In vivo treatment with EGCG for 14 days significantly attenuated the increase in SBP, alleviated the vascular dysfunction, increased the vascular cGMP and BH4 level as well as the expression of p-eNOS and decreased elevated ROS level and NOx-2 protein in angiotensin II-infused hypertensive mice. Collectively, treatment with EGCG in hypertensive mice exerts a blood pressure lowering effect which is partly attributed to the improvement in the vascular function due to its ability to reduce vascular oxidative stress in the aortic tissue leading to a decrease in eNOS uncoupling thus increasing NO bioavailability.
  19. Fulltext Sphenoid Lymphoma: A Diagnostic Challenge
    Suthersan S, Periasamy C, Noh KB, Lee SK, Husain S
    Cureus, 2023 Jun;15(6):e41058.
    PMID: 37519496 DOI: 10.7759/cureus.41058
    Sphenoid sinus lesions grasp the attention of Otorhinolaryngologists due to their prime location and vital surrounding structures. Once detected, these lesions require prompt investigation to identify the underlying cause, usually attributed to a tumor, fungal infection, sinusitis, or polyps, thus allowing tailored treatment. We report a case of an elderly lady whose neurological presentation lead to the diagnosis of sphenoid sinus lymphoma. We discuss the diagnostic challenge in view of its interesting presenting symptoms as well as the surgical approach risk and limitations.
  20. Copper complexes with phosphonium containing hydrazone ligand: topoisomerase inhibition and cytotoxicity study
    Chew ST, Lo KM, Lee SK, Heng MP, Teoh WY, Sim KS, et al.
    Eur J Med Chem, 2014 Apr 9;76:397-407.
    PMID: 24602785 DOI: 10.1016/j.ejmech.2014.02.049
    Four new copper(II) complexes containing phosphonium substituted hydrazone (L) with the formulations [CuL]Cl(3), [Cu(phen)L]Cl(4), [Cu(bpy)L]Cl(5), [Cu(dbpy)L]Cl(6), (where L = doubly deprotonated hydrazone; phen = 1,10'-phenanthroline; bpy = 2,2'-bipyridine; dbpy = 5,5'-dimethyl-2,2'-bipyridine) have been synthesized. The compounds were characterized by elemental analysis, spectroscopic methods and in the case of crystalline products by X-ray crystallography. The cytotoxicity and topoisomerase I (topo I) inhibition activities of these compounds were studied. It is noteworthy that the addition of N,N-ligands to the copper(II) complex lead to the enhancement in the cytotoxicity of the compounds, especially against human prostate adenocarcinoma cell line (PC-3). Complex 4 exhibits the highest activity against PC-3 with the IC₅₀ value of 3.2 μΜ. The complexes can also inhibit topo I through the binding to DNA and the enzyme.
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