Displaying publications 41 - 60 of 107 in total

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  1. Comparison of the complete nucleotide sequences of echovirus 7 strain UMMC and the prototype (Wallace) strain demonstrates significant genetic drift over time
    Chua BH, McMinn PC, Lam SK, Chua KB
    J Gen Virol, 2001 Nov;82(Pt 11):2629-39.
    PMID: 11602774
    The complete nucleotide sequences are reported of two strains of echovirus 7, the prototype Wallace strain (Eo7-Wallace) and a recent Malaysian strain isolated from the cerebrospinal fluid of a child with fatal encephalomyelitis (Eo7-UMMC strain). The molecular findings corroborate the serological placement of the UMMC strain as echovirus 7. Both Eo7-Wallace and Eo7-UMMC belong to the species human enterovirus B and are most closely related to echovirus 11. Eo7-UMMC has undergone significant genetic drift from the prototype strain in the 47 years that separate the isolation of the two viruses. Phylogenetic analysis revealed that Eo7-UMMC did not arise from recombination with another enterovirus serotype. The molecular basis for the severely neurovirulent phenotype of Eo7-UMMC remains unknown. However, it is shown that mutations in the nucleotide sequence of the 5' untranslated region (UTR) of Eo7-UMMC result in changes to the putative structure of the 5' UTR. It is possible that these changes contribute to the neurovirulence of Eo7-UMMC.
  2. Fulltext Second malignant neoplasms: an increasingly recognized complication of childhood cancer
    Ariffin H, Ariffin WA, Chan LL, Lam SK, Lin HP
    Med J Malaysia, 1997 Jun;52(2):174-7.
    PMID: 10968078
    Second malignant neoplasms (SMN) are an increasingly recognized late complication seen in childhood cancer survivors. A total of 3 cases of SMN have been found in the Department of Paediatrics, University Hospital Kuala Lumpur after a 15-year experience of treating childhood malignancies. Two cases are described here. The first developed abdominal non-Hodgkin's lymphoma 3 years after undergoing an allogeneic bone marrow transplant for second relapse of acute lymphoblastic leukaemia, while the second child developed myeloid leukaemia two years after completing treatment for acute lymphoblastic leukaemia. Progress in the management of childhood cancer in Malaysia and the availability of bone marrow transplantation facilities have increased the number of childhood cancer survivors; leading to increased incidence of SMN.
  3. Dengue-associated adult respiratory distress syndrome
    Lum LC, Thong MK, Cheah YK, Lam SK
    Ann Trop Paediatr, 1995 Dec;15(4):335-9.
    PMID: 8687212 DOI: 10.1080/02724936.1995.11747794
    In dengue shock syndrome, an acute increase in capillary permeability results in leakage of plasma into the interstitial space. Pleural effusion is commonly seen in dengue shock syndrome. We report three cases of dengue-associated adult respiratory distress syndrome (ARDS) in children, in all of whom dengue haemorrhagic fever, presenting with grade 3 or grade 4 dengue shock syndrome with disseminated intravascular coagulopathy, was confirmed. The criteria for the diagnosis of ARDS were based on the expanded definition of ARDS by Murray et al. Treatment consisted of fluid resuscitation, correction of coagulopathy and mechanical ventilation. All three children had multi-organ impairment, but it was more severe in the two who died. The one survivor was well at discharge.
  4. Nucleotide sequences of the nonstructural protein NS1 gene of three dengue-2 viruses, M1, M2 and M3, isolated in Malaysia from patients with dengue haemorrhagic fever, dengue shock syndrome and dengue fever, respectively
    Fong MY, Koh CL, Samuel S, Pang T, Lam SK
    Nucleic Acids Res, 1990 Mar 25;18(6):1642.
    PMID: 2139210
  5. Fulltext Acute gastroenteritis in Malaysian children: aetiological and therapeutic considerations
    Iyngkaran N, Abidin Z, Lam SK, Puthucheary SD
    Med J Malaysia, 1980 Jun;34(4):403-8.
    PMID: 7219272
    In a prospective study of 300 infants with acute gastroenteritis 150 infants had enteropathogens in the stools, 58 being due to rotavirus, 130 to adenovirus, 32 to Sahnonella, 18 Shigella and 29 E. coli. Hypernatraemic dehydration was present in 11% and acquired carbohydrate intolerance in 30% of the infants. Protracted diarrhoea was observed in 8% of infants and was commoner in the bacterial than viral group. The study shows that clinical features and simple blood tests cannot be used as reliable indices of predicting the aetiology of AGE. Despite the diverse aetiology of acute gastroenteritis, rehydration by the oral or intravenous route remained the mainstay of therapy.
    Keywords: Kuala Lumpur, university hospital,
  6. Nucleotide sequence of the envelope protein gene of a Malaysian dengue-2 virus isolated from a patient with dengue haemorrhagic fever
    Samuel S, Koh CL, Blok J, Pang T, Lam SK
    Nucleic Acids Res, 1989 Nov 11;17(21):8875.
    PMID: 2587234
  7. Nucleotide sequence of the envelope protein gene of a Malaysian dengue-2 virus isolated from a patient with dengue shock syndrome
    Samuel S, Koh CL, Blok J, Pang T, Lam SK
    Nucleic Acids Res, 1989 Nov 11;17(21):8888.
    PMID: 2587243
  8. Nucleotide sequence of the envelope protein gene of a Malaysian dengue-2 virus isolated from a patient with dengue fever
    Samuel S, Koh CL, Blok J, Pang T, Lam SK
    Nucleic Acids Res, 1989 Nov 11;17(21):8887.
    PMID: 2587242
  9. Mapping of domains responsible for nucleocapsid protein-phosphoprotein interaction of Henipaviruses
    Chan YP, Koh CL, Lam SK, Wang LF
    J Gen Virol, 2004 Jun;85(Pt 6):1675-1684.
    PMID: 15166452 DOI: 10.1099/vir.0.19752-0
    Hendra virus (HeV) and Nipah virus (NiV) are members of a new genus, Henipavirus, in the family paramyxoviridae. Each virus encodes a phosphoprotein (P) that is significantly larger than its counterparts in other known paramyxoviruses. The interaction of this unusually large P with its nucleocapsid protein (N) was investigated in this study by using recombinant full-length and truncated proteins expressed in bacteria and a modified protein-blotting protein-overlay assay. Results from our group demonstrated that the N and P of both viruses were able to form not only homologous, but also heterologous, N-P complexes, i.e. HeV N was able to interact with NiV P and vice versa. Deletion analysis of the N and P revealed that there were at least two independent N-binding sites on P and they resided at the N and C termini, respectively. Similarly, more than one P-binding site was present on N and one of these was mapped to a 29 amino acid (aa) C-terminal region, which on its own was sufficient to interact with the extreme C-terminal 165 aa region of P.
  10. Neurovirulence of four encephalitogenic dengue 3 virus strains isolated in Malaysia (1992-1994) is not attributed to their envelope protein
    Fong MY, Yusup R, Yusof R, Lam SK
    Trans R Soc Trop Med Hyg, 2004 Jun;98(6):379-81.
    PMID: 15099995
    The amino acid sequences of the envelope (E) protein of four encephalitogenic and five non-encephalitogenic dengue 3 virus strains isolated in Malaysia were determined and compared. Multiple sequence alignment revealed a high degree of similarity in the E protein of the strains suggesting that neurovirulence of these four encephalitogenic strains is not attributed to this protein.
  11. Gynura procumbens causes vasodilation by inhibiting angiotensin II and enhancing bradykinin actions
    Poh TF, Ng HK, Hoe SZ, Lam SK
    J Cardiovasc Pharmacol, 2013 May;61(5):378-84.
    PMID: 23328388 DOI: 10.1097/FJC.0b013e31828685b3
    Previous studies showed that Gynura procumbens reduced blood pressure by blocking calcium channels and inhibiting the angiotensin-converting enzyme activity. The present experiments were to further explore the effects and mechanisms of a purer aqueous fraction (FA-I) of G. procumbens on angiotensin I (Ang I)-induced and angiotensin II (Ang II)-induced contraction of aortic rings and also on the bradykinin (BK) effect on cardiovascular system. Rat aortic rings suspended in organ chambers were used to investigate the vascular reactivity of FA-I. Effect of FA-I on BK was studied by in vitro and in vivo methods. Results show that FA-I significantly (P < 0.05) decreased the contraction evoked by Ang I and Ang II. In the presence of indomethacin (10 µM) or N-nitro-L-arginine methyl ester (0.1 µM), the inhibitory effect of FA-I on Ang II-induced contraction of aortic rings was reduced. Besides, FA-I potentiated the vasorelaxant effect and enhanced the blood pressure-lowering effect of BK. In conclusion, FA-I reduced the contraction evoked by Ang II probably via the endothelium-dependent pathways, which involve activation of the release of nitric oxide and prostaglandins. The inhibition of angiotensin-converting enzyme activity by FA-I may contribute to the potentiation of the effects of BK on cardiovascular system.
  12. Fulltext First Report of Eurycoma longifolia Jack Root Extract Causing Relaxation of Aortic Rings in Rats
    Tee BH, Hoe SZ, Cheah SH, Lam SK
    Biomed Res Int, 2016;2016:1361508.
    PMID: 27800486 DOI: 10.1155/2016/1361508
    Although Eurycoma longifolia has been studied for erectile function, the blood pressure- (BP-) lowering effect has yet to be verified. Hence, this study aims at investigating the BP-lowering properties of the plant with a view to develop an antihypertensive agent that could also preserve erectile function. Ethanolic root extract was partitioned by hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The DCM fraction, found to be potent in relaxing phenylephrine- (PE-) precontracted rat aortic rings, was further purified by column chromatography. Subfraction DCM-II, being the most active in relaxing aortae, was studied for effects on the renin-angiotensin and kallikrein-kinin systems in aortic rings. The effect of DCM-II on angiotensin-converting enzyme (ACE) activity was also evaluated in vitro. Results showed that DCM-II reduced (p < 0.05) the contractions evoked by angiotensin I and angiotensin II (Ang II). In PE-precontracted rings treated with DCM-II, the Ang II-induced contraction was attenuated (p < 0.05) while bradykinin- (BK-) induced relaxation enhanced (p < 0.001). In vitro, DCM-II inhibited (p < 0.001) the activity of ACE. These data demonstrate that the vasodilatory effect of DCM-II appears to be mediated via inhibition of Ang II type 1 receptor and ACE as well as enhancement of Ang II type 2 receptor activation and BK activity.
  13. Fulltext Effects of Root Extracts of Eurycoma longifolia Jack on Corpus Cavernosum of Rat
    Tee BH, Hoe SZ, Cheah SH, Lam SK
    Med Princ Pract, 2017;26(3):258-265.
    PMID: 28226311 DOI: 10.1159/000464363
    OBJECTIVE: This study was conducted to investigate the mechanisms of action of Eurycoma longifolia in rat corpus cavernosum.

    MATERIALS AND METHODS: Tincture of the roots was concentrated to dryness by evaporating the ethanol in vacuo. This ethanolic extract was partitioned into 5 fractions sequentially with hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The corpus cavernosum relaxant activity of each fraction was investigated. The DCM fraction which showed the highest potency in relaxing phenylephrine-precontracted corpora cavernosa was purified by column chromatography. The effects of the most potent DCM subfraction in relaxing phenylephrine-precontracted corpora cavernosa, DCM-I, on angiotensin I- or angiotensin II-induced contractions in corpora cavernosa were investigated. The effects of DCM-I pretreatment on the responses of phenylephrine-precontracted corpora cavernosa to angiotensin II or bradykinin were also studied. An in vitro assay was conducted to evaluate the effect of DCM-I on angiotensin-converting enzyme activity.

    RESULTS: Fraction DCM-I decreased the maximal contractions (100%) evoked by angiotensin I and angiotensin II to 30 ± 14% and 26 ± 16% (p < 0.001), respectively. In phenylephrine-precontracted corpora cavernosa, DCM-I pretreatment caused angiotensin II to induce 82 ± 27% relaxation of maximal contraction (p < 0.01) and enhanced (p < 0.001) bradykinin-induced relaxations from 47 ± 8% to 100 ± 5%. In vitro, DCM-I was able to reduce (p < 0.001) the maximal angiotensin-converting enzyme activity to 78 ± 0.24%.

    CONCLUSION: Fraction DCM-I was able to antagonize angiotensin II-induced contraction to cause corpus cavernosum relaxation via inhibition of angiotensin II type 1 receptor and enhance bradykinin-induced relaxation through inhibition of angiotensin-converting enzyme.

  14. Bone marrow transplantation in Malaysia
    Lin HP, Chan LL, Tan A, Ariffin WA, Lam SK
    Bone Marrow Transplant, 1994 Jun;13(6):725-9.
    PMID: 7920303
    The sole BMT centre in Malaysia caters only for children. Since 1987, 89 transplants have been performed using reverse barrier nursing techniques. The overall survival rate is 73% with the majority of survivors leading normal lives. The early and late infection rates of 46% and 13%, respectively, are comparable to those of other centres. Although the early septicaemia rate is 36% the immediate mortality rate is < 10%. GVHD is less frequent and severe and the interstitial pneumonitis rate lower than that in the West. The average cost of US $8000 per transplant is much lower than the cost of a transplant performed overseas. Thus we believe that our paediatric BMT programme is simple and cost-effective.
  15. Effects of a high-salt diet on MAP and expression levels of renal ENaCs and aquaporins in SHR
    Ramachandran CD, Gholami K, Lam SK, Hoe SZ
    Exp Biol Med (Maywood), 2023 Oct;248(20):1768-1779.
    PMID: 37828834 DOI: 10.1177/15353702231198085
    An increase in blood pressure by a high-salt (HS) diet may change the expression levels of renal epithelial sodium channels (ENaCs) and aquaporins (AQPs). Spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were exposed to HS and regular-salt (RS) diets for 6 weeks. Mean arterial pressure (MAP) and plasma atrial natriuretic peptide (ANP), angiotensin II (Ang II), aldosterone, and arginine vasopressin (AVP) levels were determined. Expression of mRNA levels of ENaCs and AQPs were quantified by real-time PCR. The MAP was higher in SHRs on the HS diet. Plasma Ang II and aldosterone levels were low while plasma ANP level was high in both strains of rats. Renal expression of mRNA levels of α-, β-, and γ-ENaCs was lowered in SHRs on the HS diet. Meanwhile, renal AQP1, AQP2, and AQP7 mRNA expression levels were lowered in both strains of rats on the HS diet. Suppression of mRNA expression levels of ENaC and AQP subunits suggests that the high-salt-induced increase in the MAP of SHR may not be solely due to renal sodium and water retention.
  16. Fulltext A preliminary study of the effect of a high-salt diet on transcriptome dynamics in rat hypothalamic forebrain and brainstem cardiovascular control centers
    Ramachandran CD, Gholami K, Lam SK, Hoe SZ
    PeerJ, 2020;8:e8528.
    PMID: 32175184 DOI: 10.7717/peerj.8528
    BACKGROUND: High dietary salt intake is strongly correlated with cardiovascular (CV) diseases and it is regarded as a major risk factor associated with the pathogenesis of hypertension. The CV control centres in the brainstem (the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM)) and hypothalamic forebrain (the subfornical organ, SFO; the supraoptic nucleus, SON and the paraventricular nucleus, PVN) have critical roles in regulating CV autonomic motor outflows, and thus maintaining blood pressure (BP). Growing evidence has implicated autonomic regulatory networks in salt-sensitive HPN (SSH), but the genetic basis remains to be delineated. We hypothesized that the development and/ or maintenance of SSH is reliant on the change in the expression of genes in brain regions controlling the CV system.

    METHODOLOGY: We used RNA-Sequencing (RNA-Seq) to describe the differential expression of genes in SFO, SON, PVN, NTS and RVLM of rats being chronically fed with high-salt (HS) diet. Subsequently, a selection of putatively regulated genes was validated with quantitative reverse transcription polymerase chain reaction (qRT-PCR) in both Spontaneously Hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats.

    RESULTS: The findings enabled us to identify number of differentially expressed genes in SFO, SON, PVN, NTS and RVLM; that are either up-regulated in both strains of rats (SON- Caprin2, Sctr), down-regulated in both strains of rats (PVN- Orc, Gkap1), up-regulated only in SHRs (SFO- Apopt1, Lin52, AVP, OXT; SON- AVP, OXT; PVN- Caprin2, Sclt; RVLM- A4galt, Slc29a4, Cmc1) or down-regulated only in SHRs (SON- Ndufaf2, Kcnv1; PVN- Pi4k2a; NTS- Snrpd2l, Ankrd29, St6galnac6, Rnf157, Iglon5, Csrnp3, Rprd1a; RVLM- Ttr, Faim).

    CONCLUSIONS: These findings demonstrated the adverse effects of HS diet on BP, which may be mediated via modulating the signaling systems in CV centers in the hypothalamic forebrain and brainstem.

  17. Development of a short-term nutritional risk prediction model for hepatocellular carcinoma patients: a retrospective cohort study
    Yu J, Lam SK, He L, Wang P, Cao Y
    Sci Rep, 2024 Feb 16;14(1):3921.
    PMID: 38365922 DOI: 10.1038/s41598-024-54456-4
    Malnutrition in patients is associated with reduced tolerance to treatment-related side effects and higher risks of complications, directly impacting patient prognosis. Consequently, a pressing requirement exists for the development of uncomplicated yet efficient screening methods to detect patients at heightened nutritional risk. The aim of this study was to formulate a concise nutritional risk prediction model for prompt assessment by oncology medical personnel, facilitating the effective identification of hepatocellular carcinoma patients at an elevated nutritional risk. Retrospective cohort data were collected from hepatocellular carcinoma patients who met the study's inclusion and exclusion criteria between March 2021 and April 2022. The patients were categorized into two groups: a normal nutrition group and a malnutrition group based on body composition assessments. Subsequently, the collected data were analyzed, and predictive models were constructed, followed by simplification. A total of 220 hepatocellular carcinoma patients were included in this study, and the final model incorporated four predictive factors: age, tumor diameter, TNM stage, and anemia. The area under the ROC curve for the short-term nutritional risk prediction model was 0.990 [95% CI (0.966-0.998)]. Further simplification of the scoring rule resulted in an area under the ROC curve of 0.986 [95% CI (0.961, 0.997)]. The developed model provides a rapid and efficient approach to assess the short-term nutritional risk of hepatocellular carcinoma patients. With easily accessible and swift indicators, the model can identify patients with potential nutritional risk more effectively and timely.
  18. Hepatitis B antigen in Kuala Lumpur blood donors
    Kamath S, How VJ, Lam SK, Duraisamy G, Lopez CG, Welch Q
    Southeast Asian J Trop Med Public Health, 1973 Jun;4(2):159-64.
    PMID: 4749067
  19. Dengue encephalitis: a true entity?
    Lum LC, Lam SK, Choy YS, George R, Harun F
    Am J Trop Med Hyg, 1996 Mar;54(3):256-9.
    PMID: 8600761 DOI: 10.4269/ajtmh.1996.54.256
    Involvement of the central nervous system in dengue fever and dengue hemorrhagic fever has always been thought to be secondary to vasculitis with resultant fluid extravasation, cerebral edema, hypoperfusion, hyponatremia, liver failure, and/or renal failure. Thus, the condition has been referred to as dengue encephalopathy. Encephalitis or direct involvement of the brain by the virus was thought to be unlikely. This paper reports on six children who were seen over a period of two years presenting on the second or third day of illness with dengue encephalitis. The diagnosis was based upon a clinical picture of encephalitis and confirmed by cerebrospinal fluid (CSF) microscopy and electroencephalography changes. All six cases were confirmed dengue infections. Dengue 3 virus was isolated from the CSF of four cases and in one case, dengue 2 was detected by the polymerase chain reaction in both the CSF and blood. In the sixth case, virologic evidence was negative but dengue immunoglobulin M was detected in the CSF and blood. Since the onset of encephalitis appears early in the course of illness coinciding with the viremic phase, we postulate that the virus crosses the blood-brain barrier and directly invades the brain causing encephalitis. This study provides strong evidence that dengue 2 and 3 viruses have neurovirulent properties and behave similarly to other members of the Flaviviridae.
  20. Adenovirus in EV71-associated hand, foot, and mouth disease
    Lum LC, Wong KT, Lam SK, Chua KB, Goh AY
    Lancet, 2000 Jan 08;355(9198):146-7.
    PMID: 10675193
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