Displaying publications 1 - 20 of 31 in total

Abstract:
Sort:
  1. Sim SM, Back DJ, Breckenridge AM
    Br J Clin Pharmacol, 1991 Jul;32(1):17-21.
    PMID: 1909542
    1. Zidovudine (3'-azido-3'-deoxythymidine; AZT) is the drug of proven efficacy available for the treatment of patients with AIDS or ARC. It is eliminated mainly by hepatic glucuronidation. Therefore, interference with this metabolic pathway may lead to enhancement of AZT effect or to increased toxicity of the drug. We have examined the effect of a number of drugs which themselves undergo glucuronidation on AZT conjugation by human liver microsomes in vitro. 2. AZT glucuronidation followed Michaelis-Menten kinetics. The apparent Km and Vmax values (mean +/- s.d., n = 5), were 2.60 +/- 0.52 mM and 68.0 +/- 23.4 nmol h-1 mg-1, respectively, as determined from Eadie-Hofstee plots. 3. Dideoxyinosine, sulphanilamide and paracetamol were essentially non-inhibitory at concentrations up to 10 mM (4 times the concentration of AZT in the incubation). The most marked inhibitory effects were seen with indomethacin, naproxen, chloramphenicol, probenecid and ethinyloestradiol, with enzyme activity decreased by 97.7, 94.9, 88.7, 83.4% and 79.0%, respectively, at a concentration of 10 mM. Other compounds producing some inhibition of AZT conjugation were oxazepam, salicylic acid and acetylsalicylic acid. 4. Further studies are necessary to characterise the inhibition observed but the method described enables a screen of potentially important drug interactions to be carried out.
  2. Sim SM, Hoggard PG, Sales SD, Phiboonbanakit D, Hart CA, Back DJ
    AIDS Res Hum Retroviruses, 1998 Dec 20;14(18):1661-7.
    PMID: 9870320
    Zidovudine (ZDV) is converted to its active triphosphate (ZDVTP) by intracellular kinases. The intermediate ZDV monophosphate (ZDVMP) is believed to play a major role in ZDV toxicity. Manipulation of ZDV phosphorylation is a possible therapeutic strategy for altering the risk-benefit ratio. Here we investigate whether combining RBV with ZDV is able to modulate efficacy and toxicity of ZDV. We have measured the intracellular activation of ZDV (0.3 microM) in the absence and presence of ribavirin (RBV; 2 and 20 microM) in Molt 4 and U937 cells. MTT cytotoxicity of ZDV (10-1000 microM) was also measured with and without RBV (2 microM) in Molt 4 and U937 cells. Measurement of endogenous deoxythymidine triphosphate (dTTP) allowed investigation of the dTTP/ZDVTP ratio. The antiviral efficacy of ZDV in combination with RBV (2 microM) was assessed by HIV p24 antigen measurements. In the presence of RBV (2 and 20 microM) a decrease in total ZDV phosphates was observed, owing mainly to an effect primarily on ZDVMP rather than the active ZDVTP. RBV also increased endogenous dTTP pools in both cell types, resulting in an increase in the dTTP/ZDVTP ratio. ZDV alone significantly reduced p24 antigen production, with an IC50 of 0.34 microM. Addition of RBV increased the IC50 approximately fivefold (1.52 microM). However, at higher concentrations of ZDV (10 and 100 microM) the antagonistic effect of RBV (2 microM) on ZDV was lost. The RBV-mediated decrease in ZDVMP may explain the reduction in ZDV toxicity when combined with RBV (2 microM). Cytotoxicity of ZDV was reduced in the presence of RBV (2 microM) at all concentrations in both cell lines, probably owing to saturation of ZDVTP formation. The interaction of ZDV and RBV is concentration dependent.
  3. Azila NM, Sim SM, Atiya AS
    Ann Acad Med Singap, 2001 Jul;30(4):375-8.
    PMID: 11503543
    INTRODUCTION: Encouraging teaching practices such as problem-based learning (PBL) amongst undergraduate students within a lecture-based, system-based integrated curriculum is a challenge. Students are apprehensive about developing an organised framework for acquiring knowledge while lecturers are required to reframe their views on the educational process and their role as educators.

    MATERIALS AND METHODS: Lecturers and students in the Phase (Year) II programme were asked to fill questionnaires following the second and fourth PBL cases. The two sets of survey responses were compared to see whether the students' and teachers' perceptions had changed over the 5-month period.

    RESULTS: Students' responses from both surveys (1 and 2) were similar in that a majority agreed that the PBL tutorials had encouraged the seeking of information (66% and 67%, respectively), had improved understanding (57% and 56%), integration (65% and 70%) and application (50% and 64%) of knowledge. However, the views given in the form of written comments, following their positive responses, were somewhat contradictory. A large number of students (38% and 40%) faced difficulties in getting involved in discussions during the PBL tutorial and a majority (73% and 82%) preferred the normal subject-based tutorials. The reasons given by approximately 20% of the students were that the subject-based tutorials were more efficient for obtaining information and/or that the information had been pre-selected by the lecturers. More than 80% of the lecturers (in both surveys) perceived that the students had identified the appropriate learning objectives and covered the subject matter. The percentage of lecturers who agreed that PBL tutorials encouraged rapport and teamwork amongst students had increased in the second survey, from 70% to 92% and 55% to 83% respectively.

    CONCLUSION: Implementing PBL is not simply a matter of developing new teaching materials and new effective ways of presenting them. It requires a paradigm shift, a change in the roles of students and teachers, and time.

  4. Sim SM, Achike FI, Geh SL
    Med J Malaysia, 2005 Aug;60 Suppl D:41-7.
    PMID: 16315623
    In Malaysia many new medical schools (both public and private) have been set up in the last 12 years. As a result of global changes and local adjustments made in medical training, cross-breeds of different medical curricula have produced a wide spectrum of teaching-learning methods in these medical schools. In this paper, we have selected three medical schools--two public (Universiti Malaya and Universiti Putra Malaysia) and one private (International Medical University) to illustrate different approaches in the teaching-learning of pharmacology that exist in Malaysia. How do these different teaching-learning approaches affect the students' interest and ability to "master" pharmacology and in turn to develop a good prescribing practice?
  5. Fung SY, Tan NH, Liew SH, Sim SM, Aguiyi JC
    Trop Biomed, 2009 Apr;26(1):80-4.
    PMID: 19696731
    Seed of Mucuna pruriens (Velvet beans) has been prescribed by traditional medicine practitioners in Nigeria as a prophylactic oral antisnake remedy. In the present studies, we investigated the protective effects of M. pruriens seed extract (MPE) against histopathological changes induced by intravenous injection of Naja sputatrix (Malayan cobra) venom in rats pretreated with the seed extract. Examination by light microscope revealed that the venom induced histopathological changes in heart and blood vessels in liver, but no effect on brain, lung, kidney and spleen. The induced changes were prevented by pretreatment of the rats with MPE. Our results suggest that MPE pretreatment protects rat heart and liver blood vessels against cobra venom-induced damages.
  6. Fung SY, Tan NH, Sim SM
    Trop Biomed, 2010 Dec;27(3):366-72.
    PMID: 21399576 MyJurnal
    The protective effects of Mucuna pruriens seed extract (MPE) against the cardio-respiratory depressant and neuromuscular paralytic effects induced by injection of Calloselasma rhodostoma (Malayan pit viper) venom in anaesthetized rats were investigated. While MPE pretreatment did not reverse the inhibitory effect of the venom on the gastrocnemius muscle excitability, it significantly attenuated the venom-induced cardio-respiratory depressant effects (p < 0.05). The protection effects may have an immunological mechanism, as indicated by the presence of several proteins in the venom that are immunoreactive against anti-MPE. However, we cannot rule out the possibility that the pretreatment may exert a direct, non-immunological protective action against the venom.
  7. Sim SK, Lim SL, Lee HK, Liew D, Wong A
    Med J Malaysia, 2011 Jun;66(2):138-41.
    PMID: 22106695 MyJurnal
    Intensive care for severe head injury patients is very important in the prevention and treatment of secondary brain injury. However, in a resources constraint environment and limited availability of Intensive Care Unit (ICU) beds in the hospitals, not all severe head injury patients will receive ICU care. This prospective study is aimed to evaluate the outcome of severe head injured patients who received ICU and general ward care in Sarawak General Hospital (SGH) over a 6-month period. A total of thirty five severe head injury patients were admitted. Twenty three patients (65.7%) were ventilated in general ward whereas twelve patients (34.3%) were ventilated in ICU. Overall one month mortality in this study was 25.7%. Patients who received ICU care had a lower one month mortality than those who received general ward care (16.7% vs 30.4%), although it was not statistically different. Multivariate analysis revealed only GCS on admission (OR 0.731; 95% CI 0.460 to 0.877; P=0.042) as the independent predictive factor for one month mortality in this study.
  8. Devi RC, Sim SM, Ismail R
    PMID: 22675383 DOI: 10.1155/2012/539475
    Cymbopogon citratus has been shown to have antioxidant, antimicrobial, antispasmodic and chemo-protective properties. Citral, is the major constituent of C. citratus. This study investigated the effects of methanolic extracts of leaves (LE), stems (SE), and roots (RE) of C. citratus and citral on vascular smooth muscle and explored their possible mechanisms of action. The experiment was conducted using isolated tissue preparations, where citral, LE, SE, and RE were added separately into a tissue bath that contained aortic rings, which were pre-contracted with phenylephrine (PE). Citral, LE, and RE exhibited a dose-dependent relaxant effect on the PE-induced contractions. Citral appeared to partially act via NO as its vasorelaxant effect was attenuated by L-NAME. However, the effect of LE may involve prostacyclin as indomethacin reversed the relaxant effect of LE on the PE-induced contraction. Furthermore, citral, LE, and RE abolished the restoration of PE-induced contraction caused by the addition of increasing doses of calcium in both endothelium intact and denuded rings. These findings suggest that the relaxation effect of citral, LE, and RE is endothelium-independent and may be mainly by affecting the intracellular concentration of calcium. Citral may partially act through the NO pathway while a vasodilator prostaglandin may mediate the effect of LE.
  9. Sim SK, Ch'ng CH, Tan YC, Kandasamy R, Abdullah JM
    Med J Malaysia, 2014 Apr;69(2):86-8.
    PMID: 25241818 MyJurnal
    Subtentorial subdural empyema is a rare and life threatening intracranial suppuration. It is usually an intracranial complication of otogenic infections. Early diagnosis and surgical drainage are the most important factors determining prognosis. The high mortality reported in the literature reflects the severity of subtentorial subdural empyema if proper management is delayed. Intracranial infections usually require between 4 to 6 weeks of intravenous antibiotics therapy. However, the prolonged duration of hospitalization as well as requirement for neurosurgically inserted indwelling devices may predispose these patients to new nosocomial infections.
  10. Beshir SA, Yap LB, Sim S, Chee KH, Lo YL
    J Pharm Pharm Sci, 2017;20(1):365-377.
    PMID: 29145930 DOI: 10.18433/J3TP9Q
    PURPOSE: To assess the predicted rate and the factors associated with bleeding events among patients with non-valvular atrial fibrillation (NVAF) receiving dabigatran therapy.

    METHODS: This retrospective cohort study includes adult patients of two tertiary hospitals in Malaysia. Potential study subjects were identified using pharmacy supply database or novel oral anticoagulant (NOAC) registry. Demographics, clinical data and laboratory test results were extracted from the medical records of the patients or electronic databases. The main outcome measure is the occurrence of a bleeding event. Bleeding events were classified into major bleeding, clinically relevant non-major bleeding, or minor bleeding, according to the International Society on Thrombosis and Haemostasis criteria. We consider clinically relevant non-major bleeding events or major bleeding events as clinically relevant bleeding events. An occurrence of any bleeding event was recorded from the initiation of NOAC therapy until the death of a patient, or the date of permanent discontinuation of NOAC use, or the last day of data collection. The predicted rate of dabigatran-induced bleeding events per 100 patient-years was estimated.

    RESULTS: During a median follow-up period of 18 months, 73 patients experienced 90 bleeding events. Among these patients, 25 including 4 fatal cases, experienced major bleeding events. The predicted rate per 100 patient-years of follow-up of any bleeding events was 9.0 [95% CI 6.9 to 11.1]; clinically relevant bleeding events 6.0 [95% CI 4.8 to 8.3], and major bleeding events 3.0 [95% CI 1.9 to 4.2]. The independent risk factor for clinically relevant bleeding events is prior bleeding. While prior bleeding or congestive heart failure is linked with major bleeding events.

    CONCLUSIONS: The predicted rate for dabigatran-induced major bleeding episodes is low but these adverse events carry a high fatality risk. Preventive measures should target older patients who have prior bleeding or congestive heart failure. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

  11. Sim S, Andou Y, Bashid HAA, Lim H, Altarawneh M, Jiang Z, et al.
    ACS Omega, 2018 Dec 31;3(12):18124-18131.
    PMID: 31458398 DOI: 10.1021/acsomega.8b02478
    Graphene has attracted lots of researchers attention because of its remarkable conductivity in both electrically and thermally. However, it has poor dispersibility in organic solvents which limited its applications. Polymers with aromatic end group which act as an intercalator were prepared by ring-opening polymerization with ε-caprolactone by utilizing 1-naphthalene methanol (1-NM) as an initiator. These intercalators will exist between graphene oxide (GO) sheets to prevent aggregation via interactions. The attachment of 1-NM on polymer chains was supported by ultraviolet-visible spectra, size exclusion chromatography profiles, and 1H nuclear magnetic resonance spectra. Exfoliated structured functionalized GO (fGO)/polycaprolactone (PCL) (synthesized fGO) nanocomposites that dispersed well in acetone, chloroform, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and toluene were successfully synthesized. This agreed well with the enlarged interlayer spacing in the optimized fGO as compared to that of GO from density functional theory simulations using the DMol3 module that implemented in the Materials Studio 6.0. Furthermore, its potential to be applied as green electronics in electronics, aerospace, and automotive industries was presented, by trailering the thermal conductivity enhancement from the incorporation of fGO/PCL with commercialized biodegradable polymers, PCL, and poly[(R)-3-hydroxybutyric acid].
  12. Sim SK, Khairul Aizad A, Lim SS, Wong A
    Med J Malaysia, 2019 02;74(1):87-89.
    PMID: 30846670
    Large intracranial tumour may present only with psychiatric symptoms without any neurological deficits. Delay in surgical treatment may significantly affect the quality of life in these patients. We report a case of a young engineering student who was diagnosed as treatment-resistant depression without initial neuroimaging study. Further neuroimaging studies revealed he has a large falcine meningioma. His psychiatric symptoms resolved following surgical resection of the tumour. We emphasized the importance of initial neuroimaging study in young patients presenting with psychiatric symptoms.
  13. Ting SL, Jobli AT, Sim SK, Norlida Awang Ojep DK
    Med J Malaysia, 2019 08;74(4):338-340.
    PMID: 31424046
    We reported a case of cauda equina myxopapillary ependymoma in a patient who presented with atypical history of progressive blurring of vision. Ophthalmology examination revealed relative afferent pupillary defect, binasal hemianopia and papilloedema. This case report serves as a reminder that the intraspinal tumour could be a cause of papilloedema, despite rare, should be considered in a hydrocephalus patient who presented with no intracranial pathology and minimal spinal symptoms.
  14. Hu L, Xu Z, Wang M, Fan R, Yuan D, Wu B, et al.
    Nat Commun, 2019 10 16;10(1):4702.
    PMID: 31619678 DOI: 10.1038/s41467-019-12607-6
    Black pepper (Piper nigrum), dubbed the 'King of Spices' and 'Black Gold', is one of the most widely used spices. Here, we present its reference genome assembly by integrating PacBio, 10x Chromium, BioNano DLS optical mapping, and Hi-C mapping technologies. The 761.2 Mb sequences (45 scaffolds with an N50 of 29.8 Mb) are assembled into 26 pseudochromosomes. A phylogenomic analysis of representative plant genomes places magnoliids as sister to the monocots-eudicots clade and indicates that black pepper has diverged from the shared Laurales-Magnoliales lineage approximately 180 million years ago. Comparative genomic analyses reveal specific gene expansions in the glycosyltransferase, cytochrome P450, shikimate hydroxycinnamoyl transferase, lysine decarboxylase, and acyltransferase gene families. Comparative transcriptomic analyses disclose berry-specific upregulated expression in representative genes in each of these gene families. These data provide an evolutionary perspective and shed light on the metabolic processes relevant to the molecular basis of species-specific piperine biosynthesis.
  15. Sim SK, Tan YC, Ghani ARI
    Med J Malaysia, 2020 01;75(1):38-42.
    PMID: 32008018
    INTRODUCTION: Cerebral venous sinus thrombosis (CVST) is a potentially fatal neurological condition. However, due to the non-specific clinical and radiological features of CVST, it can sometimes result in a delay in the diagnosis and subsequent management. The aim of this study was to evaluate the demography, risk factors and one-year outcome of CVST patients treated in Hospital Universiti Sains Malaysia.

    METHODS: In this retrospective study, we reviewed the cases diagnosed with CVST admitted to our centre from January 2011 until November 2015.

    RESULTS: A total of 15 patients were included in this review. The patterns of imaging findings as well as risk factors for CVST is discussed with a review of the literature and current management practices. One year followed-up showed full recovery (Glasgow Outcome Scale (GOS) of 5) in 10 cases (66.7%), whereas 4 cases (26.7%) with GOS of 4 (three cases with neurological deficits, and 1 case with mild symptom. There was one case of mortality in this study secondary to sepsis during hospitalisation. The presenting symptoms were mainly headache, focal neurology deficits, seizure and altered sensorium. Risk factors identified were oral contraceptive pills usage, chronic sinuses or ear infections, and obesity. Initial computed tomography (CT) scan showed various findings and haemorrhagic infarct was one of the common findings. Magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) revealed majority of the patients had occlusion at two or more venous sinus sites. No patients had new or recurrent intracranial haemorrhage following initiation of anticoagulation therapy.

    CONCLUSION: Thus it is considerable safe to start anticoagulation therapy in CVST patients including those with intracranial haemorrhage. We propose further neuroimaging to avoid missed diagnosis of CVST in patient presented with recent onset headache and CT evidence of unusual cerebral infarction.

  16. Omam S, Babini MH, Sim S, Tee R, Nathan V, Namazi H
    Comput Methods Programs Biomed, 2020 Feb;184:105293.
    PMID: 31887618 DOI: 10.1016/j.cmpb.2019.105293
    BACKGROUND AND OBJECTIVE: Human body is covered with skin in different parts. In fact, skin reacts to different changes around human. For instance, when the surrounding temperature changes, human skin will react differently. It is known that the activity of skin is regulated by human brain. In this research, for the first time we investigate the relation between the activities of human skin and brain by mathematical analysis of Galvanic Skin Response (GSR) and Electroencephalography (EEG) signals.

    METHOD: For this purpose, we employ fractal theory and analyze the variations of fractal dimension of GSR and EEG signals when subjects are exposed to different olfactory stimuli in the form of pleasant odors.

    RESULTS: Based on the obtained results, the complexity of GSR signal changes with the complexity of EEG signal in case of different stimuli, where by increasing the molecular complexity of olfactory stimuli, the complexity of EEG and GSR signals increases. The results of statistical analysis showed the significant effect of stimulation on variations of complexity of GSR signal. In addition, based on effect size analysis, fourth odor with greatest molecular complexity had the greatest effect on variations of complexity of EEG and GSR signals.

    CONCLUSION: Therefore, it can be said that human skin reaction changes with the variations in the activity of human brain. The result of analysis in this research can be further used to make a model between the activities of human skin and brain that will enable us to predict skin reaction to different stimuli.

  17. Tengku Nur Alia TKA, Hing LS, Sim SF, Pradit S, Ahmad A, Ong MC
    Mar Pollut Bull, 2020 Apr;153:111009.
    PMID: 32275555 DOI: 10.1016/j.marpolbul.2020.111009
    Metallic contamination in seafood, especially fish, has been of increasing concern to human health. Moreover, with increasing dependency on farmed fish for fish resources, the metallic contamination in them is still questionable. This study aimed to investigate the effects of cooking (steaming) on heavy metal concentration in farmed fish and to estimate its potential human health risk. Farmed sea basses (Lates calcarifer) from Setiu Lagoon were used to study the difference in metal uptake through human consumption of raw and cooked (steamed) fish samples. Selected heavy metals, namely copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb), were measured using ICP-MS following Teflon bomb closed digestion of the fish samples. Cooking of the fish muscle by steaming was applied to investigate if cooking changes the concentration of heavy metals. Mercury and As were found accumulated more notably in the fish muscle, though only Hg was found to show significant (p > 0.05) increase when L. calcarifer is cooked. The amount of As in the fish muscle throughout its growth can be potentially harmful to humans, with the highest averaged concentration at 3.29 ± 0.65 mg/kg dw. above the standard set by the Malaysian Food Regulation (1985) of >1 mg/kg. All the other heavy metals were at relatively safe concentrations well below the standard set by both national and international guidelines. The PTWI per individual of L. calcarifer for As was at 0.84 mg/kg bw., which indicated that the amount of this fish safe for consumption without any adverse effect is 170 g/week. Therefore, long-term intake of these fish may pose a risk to human health due to the relatively higher Hg and As concentration found in these fishes.
  18. Sohail M, Alyson T, Sim SK, Nik Azim NA
    Med J Malaysia, 2020 09;75(5):606-608.
    PMID: 32918439
    Ileo-ileal knotting is a rare cause of intestinal obstruction. In this condition, one bowel loop makes a knot with an adjacent bowel loop, resulting in mechanical obstruction and even gangrene of the bowel. We present a case of a young girl with ileo-ileal knotting resulting in a closed-loop obstruction and gangrene of the small bowel loop. This is a difficult condition to diagnose; a high index of suspicion and early surgical intervention are essential to reduce morbidity and mortality.
  19. Kato Y, Liew BS, Sufianov AA, Rasulic L, Arnautovic KI, Dong VH, et al.
    PMID: 32922948 DOI: 10.1186/s41016-020-00194-1
    Globally, the discipline of neurosurgery has evolved remarkably fast. Despite being one of the latest medical specialties, which appeared only around hundred years ago, it has witnessed innovations in the aspects of diagnostics methods, macro and micro surgical techniques, and treatment modalities. Unfortunately, this development is not evenly distributed between developed and developing countries. The same is the case with neurosurgical education and training, which developed from only traditional apprentice programs in the past to more structured, competence-based programs with various teaching methods being utilized, in recent times. A similar gap can be observed between developed and developing counties when it comes to neurosurgical education. Fortunately, most of the scholars working in this field do understand the coherent relationship between neurosurgical education and neurosurgical practice. In context to this understanding, a symposium was organized during the World Federation of Neurological Surgeons (WFNS) Special World Congress Beijing 2019. This symposium was the brain child of Prof. Yoko Kato-one of the eminent leaders in neurosurgery and an inspiration for female neurosurgeons. Invited speakers from different continents presented the stages of development of neurosurgical education in their respective countries. This paper summarizes the outcome of these presentations, with particular emphasis on and the challenges faced by developing countries in terms of neurosurgical education and strategies to cope with these challenges.
Related Terms
Filters
Contact Us

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

External Links