Displaying all 12 publications

  1. Tan LS, Tan S
    Med J Malaysia, 2018 02;73(1):54-56.
    PMID: 29531206 MyJurnal
    Tuberculosis (TB) is still an endemic disease in Malaysia. Cystic lung disease in post primary tuberculosis is not common. It can occur before, during or after completion of anti-TB treatment. Clinical history and review of serial chest radiograph is paramount to make the diagnosis. This case report highlights an interesting case of a young female patient who developed extensive cystic lung disease during the course of anti-TB treatment and the importance of recognizing this unusual manifestation.
  2. Tan LS, Daud MH, Nasirudin N
    J Hand Surg Asian Pac Vol, 2018 Dec;23(4):577-580.
    PMID: 30428790 DOI: 10.1142/S2424835518720335
    Pyogenic granuloma, also known as lobular capillary hemangioma, is a benign vascular lesion of the skin or mucous membrane with rapid growth or repetitive trauma. Rarely seen in adult, its management varies and surgical intervention is usually common. We report a case of pyogenic granuloma of the right index finger in a 46-year-old gentleman who presented with painless swelling of the right index finger after a trivial injury. Wedge biopsy confirmed the diagnosis and excision of the granuloma measuring 3 cm × 3 cm × 2 cm was done with curettage and electrocautery over the base of granuloma. The wound subsequently healed well with good functional and aesthetic outcome.
  3. Ng SF, Tan LS, Buang F
    Drug Dev Ind Pharm, 2017 Jan;43(1):108-119.
    PMID: 27588411 DOI: 10.1080/03639045.2016.1224893
    Previous studies have shown that hydroxytyrosol (HT) can be a potential alternative therapeutic agent for the treatment of rheumatoid arthritis (RA). However, HT is extensively metabolized following oral administration, which leads to formulating HT in a topical vehicle to prolong drug action as well as to provide a localized effect. Hidrox-6 is a freeze-dried powder derived from fresh olives and contains a high amount of HT (∼3%) and other polyphenols. Alginate bilayer films containing 5% and 10% Hidrox-6 were formulated. The films were characterized with respect to their physical, morphology, rheological properties; drug content uniformity; and in vitro drug release. Acute dermal irritancy tests and a skin sensitization study were carried out in rats. An efficacy study of the bilayer films for RA was conducted using Freund's adjuvant-induced polyarthritis rats. Animal data showed that the bilayer film formulations did not cause skin irritancy. The efficacy in vivo results showed that the Hidrox-6 bilayer films lowered the arthritic scores, paw and ankle circumference, serum IL-6 level and cumulative histological scores compared with those measured for controls. The topical Hidrox-6 bilayer films improve synovitis and inflammatory symptoms in RA and can be a potential alternative to oral RA therapy.
  4. Basri DF, Tan LS, Shafiei Z, Zin NM
    PMID: 22203875 DOI: 10.1155/2012/632796
    The galls of Quercus infectoria are commonly used in Malay traditional medicine to treat wound infections after childbirth. In India, they are employed traditionally as dental applications such as that in treatment of toothache and gingivitis. The aim of the present study was to evaluate the antibacterial activity of galls of Quercus infectoria Olivier against oral bacteria which are known to cause dental caries and periodontitis. Methanol and acetone extracts were screened against two Gram-positive bacteria (Streptococcus mutans ATCC 25175 and Streptococcus salivarius ATCC 13419) and two Gram-negative bacteria (Porphyromonas gingivalis ATCC 33277 and Fusobacterium nucleatum ATCC 25586). The screening test of antibacterial activity was performed using agar-well diffusion method. Subsequently, minimum inhibitory concentration (MIC) was determined by using twofold serial microdilution method at a concentration ranging between 0.01 mg/mL and 5 mg/mL. Minimum bactericidal concentration (MBC) was obtained by subculturing microtiter wells which showed no changes in colour of the indicator after incubation. Both extracts showed inhibition zones which did not differ significantly (P < 0.05) against each tested bacteria. Among all tested bacteria, S. salivarius was the most susceptible. The MIC ranges for methanol and acetone extracts were the same, between 0.16 and 0.63 mg/mL. The MBC value, for methanol and acetone extracts, was in the ranges 0.31-1.25 mg/mL and 0.31-2.50 mg/mL, respectively. Both extracts of Q. infectoria galls exhibited similar antibacterial activity against oral pathogens. Thus, the galls may be considered as effective phytotherapeutic agents for the prevention of oral pathogens.
  5. Ahmad AL, Tan LS, Abd Shukor SR
    J Hazard Mater, 2008 Jun 15;154(1-3):633-8.
    PMID: 18055106
    This study examined the performance of nanofiltration membranes to retain atrazine and dimethoate in aqueous solution under different pH conditions. Four nanofiltration membranes, NF90, NF200, NF270 and DK are selected to be examined. The operating pressure, feed pesticide and stirring rate were kept constant at 6x10(5) Pa, 10 mg/L and 1000 rpm. It was found that increasing the solution's pH increased atrazine and dimethoate rejection but reduced the permeate flux performance for NF200, NF270 and DK. However, NF90 showed somewhat consistent performance in both rejection and permeate flux regardless of the solution's pH. NF90 maintained above 90% of atrazine rejection and approximately 80% of dimethoate rejection regardless of the changes in solution's pH. Thus, NF90 is deemed the more suitable nanofiltration membrane for atrazine and dimethoate retention from aqueous solution compared to NF200, NF270 and DK.
  6. Ahmad AL, Tan LS, Shukor SR
    J Hazard Mater, 2008 Feb 28;151(1):71-7.
    PMID: 17587496
    In order to produce sufficient food supply for the ever-increasing human population, pesticides usage is indispensable in the agriculture sector to control crop losses. However, the effect of pesticides on the environment is very complex as undesirable transfers occur continually among different environmental sections. This eventually leads to contamination of drinking water source especially for rivers located near active agriculture practices. This paper studied the application of nanofiltration membrane in the removal of dimethoate and atrazine in aqueous solution. Dimethoate was selected as the subject of study since it is being listed as one of the pesticides in guidelines for drinking water by World Health Organization. Nevertheless, data on effectiveness of dimethoate rejection using membranes has not been found so far. Meanwhile, atrazine is classified as one of the most commonly used pesticides in Malaysia. Separation was done using a small batch-type membrane separation cell with integrated magnetic stirrer while concentration of dimethoate and atrazine in aqueous solution was analyzed using high performance liquid chromatography (HPLC). Four nanofiltration membranes NF90, NF200, NF270 and DK were tested for their respective performance to separate dimethoate and atrazine. Of all four membranes, NF90 showed the best performance in retention of dimethoate and atrazine in water.
  7. Soo JAL, Makhtar MMZ, Shoparwe NF, Otitoju TA, Mohamad M, Tan LS, et al.
    Membranes (Basel), 2021 Aug 31;11(9).
    PMID: 34564493 DOI: 10.3390/membranes11090676
    Textile industry effluent contains a high amount of toxic colorants. These dyes are carcinogenic and threats to the environment and living beings. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was used as the based polymer for PIMs with bis-(2-ethylhexyl) phosphate (B2EHP) and dioctyl phthalate (DOP) as the carrier and plasticizer. The fabricated PIMs were employed to extract the cation dye (Malachite Green; MG) from the feeding phase. PIMs were also characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), contact angle, water uptake, Fourier-transform infrared spectroscopy (FTIR) and ions exchange capacity. The performance of the PIMs was investigated under various conditions such as percentage of carrier and initial dye concentration. With permeability and flux values of 0.1188 cm/min and 1.1913 mg cm/min, PIM produced with 18% w/w PVDF-co-HFP, 21% w/w B2EHP, 1% w/w DOP and 40% w/w THF and was able to achieve more than 97% of MG extraction. The experimental data were then fitted with a pseudo-second-order (PSO) model, and the calculated R2 value was ~0.99. This shows that the data has a good fit with the PSO model. PIM is a potential alternative technology in textile industry effluent treatment; however, the right formulation is crucial for developing a highly efficient membrane.
  8. Mohan A, Manan K, Tan LS, Tan YC, Chin ST, Ahmad R, et al.
    Int J Infect Dis, 2020 Sep;98:59-66.
    PMID: 32535300 DOI: 10.1016/j.ijid.2020.06.025
    OBJECTIVES: Melioidosis is associated with extremely high case fatality ratios. The aim of this study was to determine whether detection of abdominal visceral abscesses can facilitate diagnosis of melioidosis in children.

    METHODS: We conducted a retrospective analysis of all children who had liver and/or spleen abscesses on abdominal ultrasonography admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2014 until December 2018.

    RESULTS: Fifty-three children had liver and/or spleen abscesses. Spleen abscesses were present in 48 (91%) cases; liver abscesses in 15 (28%). Melioidosis was confirmed by culture in 9 (17%) children; small occult splenic abscesses were present in all cases. In 78% of these cases, the lesions were detected before any positive culture (or serology) results were available. Four (8%) children had bacteriologically-confirmed tuberculosis. Two (4%) had Staphylococcus aureus infection. Of the remaining 38 (72%) culture-negative cases, 36 (95%) had clinical and imaging characteristics similar to that of children with culture-confirmed melioidosis and improved with empirical melioidosis antibiotic therapy.

    CONCLUSIONS: A large number of children in Bintulu Hospital in Sarawak, Malaysia, were found to have spleen abscesses. Melioidosis was the most common etiology identified in these children. Abdominal ultrasonography is extremely useful in facilitating the diagnosis of pediatric melioidosis.

  9. Sia TLL, Mohan A, Ooi MH, Chien SL, Tan LS, Goh C, et al.
    Open Forum Infect Dis, 2021 Oct;8(10):ofab460.
    PMID: 34646909 DOI: 10.1093/ofid/ofab460
    Background: Burkholderia pseudomallei, the causative agent of melioidosis, is intrinsically resistant to a broad range of antibiotics, including aminoglycosides. In Sarawak, Malaysia, a high proportion of melioidosis cases are caused by gentamicin-susceptible isolates. There are limited epidemiological and clinical data on these infections.

    Methods: We conducted a retrospective study of culture-confirmed melioidosis among adults admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2011 until December 2016.

    Results: One hundred forty-eight adults with culture-confirmed melioidosis were identified. Of 129 (87%) tested, 84 (65%) had gentamicin-susceptible B pseudomallei. The average annual incidence of melioidosis was 12.3 per 100 000 population, with marked variation between districts ranging from 5.8 to 29.3 per 100 000 population. Rural districts had higher incidences of melioidosis and overwhelmingly larger proportions of gentamicin-susceptible B pseudomallei infection. Significantly more patients with gentamicin-susceptible infection had no identified risk factors, with diabetes less frequently present in this group. Ninety-eight percent had acute presentations. Pneumonia, reported in 71%, was the most common presentation. Splenic abscesses were found in 54% of those imaged. Bacteremia was present in 88%; septic shock occurred in 47%. Forty-five (35%) patients died. No differences in clinical, laboratory, or outcome characteristics were noted between gentamicin-susceptible and gentamicin-resistant infections.

    Conclusions: Gentamicin-susceptible B pseudomallei infections are common in Sarawak and dominate in the high-incidence rural interior regions. Clinical manifestations and outcomes are the same as for gentamicin-resistant B pseudomallei infections. Further studies are required to determine if all gentamicin-susceptible B pseudomallei infections in Sarawak are clonal and to ascertain their environmental drivers and niches.

  10. Sia TLL, Mohan A, Ooi MH, Chien SL, Tan LS, Goh C, et al.
    Open Forum Infect Dis, 2022 Feb;9(2):ofab653.
    PMID: 35097155 DOI: 10.1093/ofid/ofab653
    [This corrects the article DOI: 10.1093/ofid/ofab460.].
  11. Mohan A, Podin Y, Liew DW, Mahendra Kumar J, Lau PS, Tan YY, et al.
    BMC Infect Dis, 2021 Oct 15;21(1):1069.
    PMID: 34654392 DOI: 10.1186/s12879-021-06754-9
    BACKGROUND: Melioidosis, the infection caused by Burkholderia pseudomallei, is associated with a high case fatality rate, due in part to difficulties in clinical recognition and diagnostic confirmation of the disease. Although head and neck involvement is common in children, specific disease manifestations differ between geographic regions. The aim of this study was to provide a detailed description of melioidosis of the head and neck among children in Sarawak, Malaysia, and determine if fine-needle aspiration of suspected head or neck lesions could improve melioidosis diagnosis.

    METHODS: We conducted a retrospective descriptive study of all children aged

  12. Mohan A, Podin Y, Tai N, Chieng CH, Rigas V, Machunter B, et al.
    PLoS Negl Trop Dis, 2017 Jun;11(6):e0005650.
    PMID: 28599008 DOI: 10.1371/journal.pntd.0005650
    BACKGROUND: Melioidosis is a serious, and potentially fatal community-acquired infection endemic to northern Australia and Southeast Asia, including Sarawak, Malaysia. The disease, caused by the usually intrinsically aminoglycoside-resistant Burkholderia pseudomallei, most commonly affects adults with predisposing risk factors. There are limited data on pediatric melioidosis in Sarawak.

    METHODS: A part prospective, part retrospective study of children aged <15 years with culture-confirmed melioidosis was conducted in the 3 major public hospitals in Central Sarawak between 2009 and 2014. We examined epidemiological, clinical and microbiological characteristics.

    FINDINGS: Forty-two patients were recruited during the 6-year study period. The overall annual incidence was estimated to be 4.1 per 100,000 children <15 years, with marked variation between districts. No children had pre-existing medical conditions. Twenty-three (55%) had disseminated disease, 10 (43%) of whom died. The commonest site of infection was the lungs, which occurred in 21 (50%) children. Other important sites of infection included lymph nodes, spleen, joints and lacrimal glands. Seven (17%) children had bacteremia with no overt focus of infection. Delays in diagnosis and in melioidosis-appropriate antibiotic treatment were observed in nearly 90% of children. Of the clinical isolates tested, 35/36 (97%) were susceptible to gentamicin. Of these, all 11 isolates that were genotyped were of a single multi-locus sequence type, ST881, and possessed the putative B. pseudomallei virulence determinants bimABp, fhaB3, and the YLF gene cluster.

    CONCLUSIONS: Central Sarawak has a very high incidence of pediatric melioidosis, caused predominantly by gentamicin-susceptible B. pseudomallei strains. Children frequently presented with disseminated disease and had an alarmingly high death rate, despite the absence of any apparent predisposing risk factor.

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