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  1. Ng HS, Kee PE, Tan GY, Yim HS, Lan JC
    Appl Biochem Biotechnol, 2020 May;191(1):273-283.
    PMID: 32335865 DOI: 10.1007/s12010-020-03284-z
    Garcinia mangostana pericarp is a good source of natural antioxidants with numerous functional properties. The conventional approaches for the recovery of antioxidants from Garcinia mangostana pericarp require long processing time and high temperature, which may cause degradation or loss of bioactivity of antioxidants, and often result in low recovery efficiency. In this study, the extraction of antioxidants from Garcinia mangostana pericarp was investigated using a polyethylene glycol (PEG)/citrate aqueous biphasic system (ABS) with the addition of surfactants. The optimum condition for the recovery of antioxidants was achieved in PEG 1000/citrate ABS of pH 8 with tie-line length (TLL) of 48.3% (w/w), volume ratio (VR) of 1.6, 0.2% (w/w) sample loading and addition of 1.0% (w/w) Tween 85. The antioxidants were recovered in the PEG-rich top phase with a high K value of 18.23 ± 0.33 and a recovery yield of 92.01% ± 0.09. The findings suggested that the addition of surfactants to polymer/salt ABS can enhance the recovery of antioxidants from Garcinia mangostana pericarps by conserving the antioxidative properties.
  2. Tan PC, Abdussyukur SA, Lim BK, Win ST, Omar SZ
    BJOG, 2020 10;127(11):1430-1437.
    PMID: 32356413 DOI: 10.1111/1471-0528.16290
    OBJECTIVE: To evaluate fasting for 12 hours compared with expedited oral feeding in hospitalised women with hyperemesis gravidarum (HG).

    DESIGN: Randomised trial.

    SETTING: University Hospital, Malaysia: April 2016-April 2017.

    POPULATION: One hundred and sixty women hospitalised for HG.

    METHOD: Women were randomised upon admission to fasting for 12 hours or expedited oral feeding. Standard HG care was instituted.

    MAIN OUTCOME MEASURE: Primary outcome was satisfaction score with overall treatment at 24 hours (0-10 Visual Numerical Rating Scale VNRS), vomiting episodes within 24 hours and nausea VNRS score at enrolment, and at 8, 16 and 24 hours.

    RESULTS: Satisfaction score, median (interquartile range) 8 (5-9) versus 8 (7-9) (P = 0.08) and 24-hour vomiting episodes were 1 (0-4) versus 1 (0-5) (P = 0.24) for 12-hour fasting versus expedited feeding, respectively. Repeated measures analysis of variance of nausea scores over 24 hours showed no difference (P = 0.11) between trial arms. Participants randomised to 12-hour fasting compared with expedited feeding were less likely to prefer their feeding regimen in future hospitalisation (41% versus 65%, P = 0.001), to recommend to a friend (65% versus 84%, P = 0.01; RR 0.8, 95% CI 0.6-0.9) and to adhere to protocol (85% versus 95%, P = 0.04; RR 0.9, 95% CI 0.8-1.0). Symptoms profile, ketonuria status at 24 hours and length of hospital stay were not different.

    CONCLUSION: Advisory of 12-hour fasting compared with immediate oral feeding resulted in a non-significant difference in satisfaction score but adherence to protocol and fidelity to and recommendation of immediate oral feeding to a friend were lower. The 24-hour nausea scores and vomiting episodes were similar.

    TWEETABLE ABSTRACT: Women hospitalised for hyperemesis gravidarum could feed as soon, as much and as often as can be tolerated compared with initial fasting.

  3. Yeap JS, Tan CH, Yong KT, Lim KH, Lim SH, Low YY, et al.
    Phytochemistry, 2020 Aug;176:112391.
    PMID: 32387883 DOI: 10.1016/j.phytochem.2020.112391
    Fourteen previously undescribed alkaloids comprising two N-1-hydroxymethylmacroline alkaloids, one talpinine-type oxindole acetal, a pair of equilibrating talpinine-type oxindole hemiacetals, eight oxidized derivatives of sarpagine- and akuammiline-type indole alkaloids, in addition to alstochalotine a diastereomer of gelsochalotine recently isolated from Gelsemium elegans, were isolated from the leaf and stem-bark extracts of Alstonia penangiana. The structures and relative configurations of these alkaloids were established using NMR, MS, and in one instance, confirmed by X-ray diffraction analysis. An NMR-based method is described as a useful chemotaxonomic tool for differentiating between A. penangiana and A. macrophylla. Several of the alkaloids isolated showed appreciable growth inhibitory effects when tested against a number of human cancer cell lines.
  4. Liew YJM, Lee YK, Khalid N, Rahman NA, Tan BC
    PeerJ, 2020;8:e9094.
    PMID: 32391211 DOI: 10.7717/peerj.9094
    Flavonoids and prenylated flavonoids are active components in medicinal plant extracts which exhibit beneficial effects on human health. Prenylated flavonoids consist of a flavonoid core with a prenyl group attached to it. This prenylation process is catalyzed by prenyltranferases (PTs). At present, only a few flavonoid-related PT genes have been identified. In this study, we aimed to investigate the roles of PT in flavonoid production. We isolated a putative PT gene (designated as BrPT2) from a medicinal ginger, Boesenbergia rotunda. The deduced protein sequence shared highest gene sequence homology (81%) with the predicted homogentisate phytyltransferase 2 chloroplastic isoform X1 from Musa acuminata subsp. Malaccensis. We then cloned the BrPT2 into pRI vector and expressed in B. rotunda cell suspension cultures via Agrobacterium-mediated transformation. The BrPT2-expressing cells were fed with substrate, pinostrobin chalcone, and their products were analyzed by liquid chromatography mass spectrometry. We found that the amount of flavonoids, namely alpinetin, pinostrobin, naringenin and pinocembrin, in BrPT2-expressing cells was higher than those obtained from the wild type cells. However, we were unable to detect any targeted prenylated flavonoids. Further in-vitro assay revealed that the reaction containing the BrPT2 protein produced the highest accumulation of pinostrobin from the substrate pinostrobin chalcone compared to the reaction without BrPT2 protein, suggesting that BrPT2 was able to accelerate the enzymatic reaction. The finding of this study implied that the isolated BrPT2 may not be involved in the prenylation of pinostrobin chalcone but resulted in high yield and production of other flavonoids, which is likely related to enzyme promiscuous activities.
  5. Ninyio NN, Ho KL, Ong HK, Yong CY, Chee HY, Hamid M, et al.
    Vaccines (Basel), 2020 Jun 04;8(2).
    PMID: 32512923 DOI: 10.3390/vaccines8020275
    Chimeric virus-like particles (VLPs) have been widely exploited for various purposes including their use as vaccine candidates, particularly due to their ability to induce stronger immune responses than VLPs consisting of single viral proteins. In the present study, VLPs of the Macrobrachium rosenbergii nodavirus (MrNV) capsid protein (Nc) displaying the hepatitis B virus "a" determinant (aD) were produced in Spodoptera frugiperda (Sf9) insect cells. BALB/c mice immunised with the purified chimeric Nc-aD VLPs elicited a sustained titre of anti-aD antibody, which was significantly higher than that elicited by a commercially available hepatitis B vaccine and Escherichia coli-produced Nc-aD VLPs. Immunophenotyping showed that the Sf9-produced Nc-aD VLPs induced proliferation of cytotoxic T-lymphocytes and NK1.1 natural killer cells. Furthermore, enzyme-linked immunospot (ELISPOT)analysis showed the presence of antibody-secreting memory B cells in the mice splenocytes stimulated with the synthetic aD peptide. The significant humoral, natural killer cell and memory B cell immune responses induced by the Sf9-produced Nc-aD VLPs suggest that they present good prospects for use as a hepatitis B vaccine candidate.
  6. Chua KH, Tan EW, Chai HC, Puthucheary SD, Lee PC, Puah SM
    PeerJ, 2020;8:e9238.
    PMID: 32518734 DOI: 10.7717/peerj.9238
    Background: Burkholderia pseudomallei causes melioidosis, a serious illness that can be fatal if untreated or misdiagnosed. Culture from clinical specimens remains the gold standard but has low diagnostic sensitivity.

    Method: In this study, we developed a rapid, sensitive and specific insulated isothermal Polymerase Chain Reaction (iiPCR) targeting bimA gene (Burkholderia Intracellular Motility A; BPSS1492) for the identification of B. pseudomallei. A pair of novel primers: BimA(F) and BimA(R) together with a probe were designed and 121 clinical B. pseudomallei strains obtained from numerous clinical sources and 10 ATCC non-targeted strains were tested with iiPCR and qPCR in parallel.

    Results: All 121 B. pseudomallei isolates were positive for qPCR while 118 isolates were positive for iiPCR, demonstrating satisfactory agreement (97.71%; 95% CI [93.45-99.53%]; k = 0.87). Sensitivity of the bimA iiPCR/POCKIT assay was 97.52% with the lower detection limit of 14 ng/µL of B. pseudomallei DNA. The developed iiPCR assay did not cross-react with 10 types of non-targeted strains, indicating good specificity.

    Conclusion: This bimA iiPCR/POCKIT assay will undoubtedly complement other methodologies used in the clinical laboratory for the rapid identification of this pathogen.

  7. Leong Bin Abdullah MFI, Tan KL, Mohd Isa S, Yusoff NS, Chear NJY, Singh D
    PLoS One, 2020;15(6):e0234639.
    PMID: 32525924 DOI: 10.1371/journal.pone.0234639
    BACKGROUND AND AIM: Kratom, or Mitragyna speciosa Korth., is a tropical plant that has been reported to exhibit opioid-like effects. Although opioids have been demonstrated to alter the lipid profile of regular users, data on the lipid-altering effects of kratom are scarce. This study aimed to compare the fasting lipid profile of regular kratom users to that of healthy subjects who do not use kratom. It also determined the association between various characteristics of kratom users and the serum triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels of regular kratom users.

    METHODS: A total of 200 participants (n = 100 kratom users and n = 100 healthy subjects who do not use kratom) were recruited for this analytical cross-sectional study. Data on sociodemographic status, kratom use characteristics, cigarette smoking, physical activity, body mass index (BMI), fasting serum lipid profile, and liver function were collected from all participants.

    RESULTS: The liver parameters of the study participants were within normal range. The serum total cholesterol and LDL of kratom users were significantly lower than those of healthy subjects who do not use kratom. There were no significant differences in the serum triglyceride and HDL levels. However, higher average daily frequency of kratom use and increasing age were associated with increased serum total cholesterol among kratom users. Other kratom use characteristics such as age of first kratom intake, duration of kratom use, and quantity of daily kratom intake were not associated with increased serum triglyceride, total cholesterol, LDL, and HDL levels.

    CONCLUSIONS: Our findings suggest regular kratom consumption was not linked to elevated serum lipids, except when there is a higher frequency of daily kratom intake. However, the study was limited by the small sample size, and hence a more comprehensive study with larger sample size is warranted to confirm the findings.

  8. Mohammed F, Tan GC, Hor KN, Arnold M, Wong YP
    Cardiovasc. Pathol., 2020 05 12;49:107226.
    PMID: 32574866 DOI: 10.1016/j.carpath.2020.107226
    Cardiac rhabdomyoma is the most prevalent cardiac tumors in the pediatric population, in close association with tuberous sclerosis complex. It is usually detected antenatally or postnatally by echocardiography. Clinical presentations depend greatly on the size and position of the tumor mass. Interestingly, rhabdomyoma has a propensity to regress spontaneously and is not usually operated upon, unless the patient becomes hemodynamically compromised. Herein, we report an unusual case of surgically treated cardiac rhabdomyoma in a baby boy presented at birth with a progressive enlarging intraventricular mass, complicated with left ventricular outflow tract obstruction 7 weeks later. Histopathological examination of the intracardiac mass revealed sheets of tumor cells with spider-like morphology (known as "spider cells"), confirmed the diagnosis of rhabdomyoma. Close disease monitoring of patient's hemodynamic status in a newly diagnosed cardiac rhabdomyoma is inevitable as the tumor, although rare, may progress.
  9. Wang Q, Luo Y, Ray Chaudhuri K, Reynolds R, Tan EK, Pettersson S
    Brain, 2021 Oct 22;144(9):2571-2593.
    PMID: 33856024 DOI: 10.1093/brain/awab156
    Parkinson's disease is a common neurodegenerative disorder in which gastrointestinal symptoms may appear prior to motor symptoms. The gut microbiota of patients with Parkinson's disease shows unique changes, which may be used as early biomarkers of disease. Alterations in the gut microbiota composition may be related to the cause or effect of motor or non-motor symptoms, but the specific pathogenic mechanisms are unclear. The gut microbiota and its metabolites have been suggested to be involved in the pathogenesis of Parkinson's disease by regulating neuroinflammation, barrier function and neurotransmitter activity. There is bidirectional communication between the enteric nervous system and the CNS, and the microbiota-gut-brain axis may provide a pathway for the transmission of α-synuclein. We highlight recent discoveries about alterations to the gut microbiota in Parkinson's disease and focus on current mechanistic insights into the microbiota-gut-brain axis in disease pathophysiology. Moreover, we discuss the interactions between the production and transmission of α-synuclein and gut inflammation and neuroinflammation. In addition, we draw attention to diet modification, the use of probiotics and prebiotics and faecal microbiota transplantation as potential therapeutic approaches that may lead to a new treatment paradigm for Parkinson's disease.
  10. Teo CS, Tan PM, Shu CSI, Choo ZX, Te KK
    Integr Med Res, 2021;10:100783.
    PMID: 34642627 DOI: 10.1016/j.imr.2021.100783
    Background: Implementing Chinese medicine (CM) for COVID-19 in Malaysia is challenging for local CM practitioners. The successful experience of CM in China can only be partially adopted in Malaysia due to differences in the national health care system and legislation, geographical health disparities and cultural diversity. Despite all the challenges, Malaysian CM practitioners have managed to thrive and found a Malaysian CM solution amid COVID-19.

    Methods: A literature review was conducted using various databases and gray literature from inception to August 15, 2021, to evaluate the challenges faced by Malaysian CM practitioners and the corresponding strategies in Malaysia's country context during COVID-19.

    Results: A total of 9 challenges and issues faced by Malaysian CM practitioners during COVID-19 were identified. Their corresponding strategies were further categorized into 3 phases, namely, preparation, development and implementation. The strategies were appraised using the SWOT analysis method, and 17 factors were identified. Strength analysis includes personalized CM prescriptions with online consultations in Malaysia. Limited research input for CM in COVID-19 and the inadequate research capacity of local CM institutions are discussed in threat analysis.

    Conclusion: Various approaches have been implemented by Malaysian CM practitioners to provide safe, qualified and effective CM services for COVID-19 at the community level, aiming to reduce the national health care burden. A public-private partnership initiative can bridge the knowledge gap and optimize the role of CM in the health emergency system. This Malaysian CM solution can provide insights to interested countries to capitalize on the potential contribution of Traditional and Complementary Medicine (T&CM) in the era of COVID-19.

  11. Chan WK, Tan AT, Vethakkan SR, Tah PC, Vijayananthan A, Goh KL
    J Gastroenterol Hepatol, 2013 Aug;28(8):1375-83.
    PMID: 23517307 DOI: 10.1111/jgh.12204
    BACKGROUND AND AIM:
    There is currently no published study comparing prevalence of non-alcoholic fatty liver disease (NAFLD) and associated factors among diabetics of different ethnicity in the Asia-Pacific region.

    METHODS:
    Cross-sectional study of consecutive patients in the Diabetic Clinic in University of Malaya Medical Centre. The Global Physical Activity Questionnaire and a semiquantitative food-frequency questionnaire were used to assess physical activity and dietary intake, respectively. Diagnosis of NAFLD was ultrasound-based and following exclusion of significant alcohol intake.

    RESULTS:
    Data for 399 patients were analyzed (mean age 62.3 ± 10.5 years, 43.1% men). The racial distribution was Chinese 43.6%, Indian 33.1%, Malay 22.3%, and others 1.0%. The prevalence of NAFLD was 49.6%. On univariate analysis, factors associated with NAFLD were age < 65 years, race, obesity, central obesity, glycated hemoglobin ≥ 7.0%, and elevated serum alanine aminotransferase (ALT) and gamma-glutamyl transpeptidase levels. Patients with low physical activity were more likely to have NAFLD (odds ratio [OR] = 1.67, 95% confidence interval [CI] = 1.06-2.63, P = 0.020). The prevalence of NAFLD was highest among Malays (60.7%), followed by Indians (51.5%), and lowest among Chinese (42.0%) consistent with higher prevalence of central obesity and higher percentage calorie intake from fat in the former groups of patients. On multivariate analysis, independent factors associated with NAFLD were central obesity (OR = 2.20, 95% CI = 1.29-3.75, P = 0.004) and elevated serum ALT level (OR = 1.98, 95% CI = 1.21-3.25, P = 0.007).

    CONCLUSIONS:
    NAFLD was seen in half of a cohort of diabetic patients and was independently associated with central obesity and elevated serum ALT level. Prevalence of NAFLD was different and paralleled the difference in prevalence of central obesity and in percentage calorie intake from fat among the different ethnic groups.

    © 2013 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

    KEYWORDS:
    diabetes mellitus; dietary intake; epidemiology; ethnicity; non-alcoholic fatty liver disease; physical activity
    Study site: Diabetic clinic, University Malaya Medical Centre (UMMC)
  12. Liu H, Gu H, Kutbi EH, Tan SC, Low TY, Zhang C
    Int J Clin Pract, 2021 Nov;75(11):e14764.
    PMID: 34469629 DOI: 10.1111/ijcp.14764
    PURPOSE: Many studies have investigated the association between serum IGF-1 and IGFBP levels with gastric cancer (GC), but the results remained inconclusive. In this work, we performed a systematic review and meta-analysis to examine the precise association of serum levels of IGF-1 and IGFBP with GC.

    METHODS: A comprehensive systematic search was carried out in PubMed/MEDLINE, SCOPUS, Web of Science, and EMBASE databases for (nested) case-control studies that reported the levels of IGF-1 and IGFBP in GC cases and healthy controls, from inception until October 2020. Weighted mean difference (WMD) was calculated for estimating combined effect size. Subgroup analysis was performed to identify the source of heterogeneity among studies.

    RESULTS: We found eight and five eligible studies (with 1541 participants) which provided data for IGF-1 and IGFBP, respectively. All studies on IGFBP reported the IGFBP-3 isoform. The pooled results indicate that GC patients had significantly lower serum IGF-1 [WMD = -26.21 ng/mL (95% CI, -45.58 to -6.85; P = .008)] and IGFBP-3 [WMD = -0.41 ng/mL (95% CI, -0.80 to -0.01; P = .04; I2  = 89.9%; P 

  13. Foong SC, Tan ML, Foong WC, Ho JJ, Rahim FF
    Int Breastfeed J, 2021 01 06;16(1):4.
    PMID: 33407645 DOI: 10.1186/s13006-020-00353-1
    BACKGROUND: Ethnic Chinese mothers in Malaysia adhere to 30 days of traditional postpartum practices (the "confinement period") aimed at recuperation after delivery. Recently there has been an emergence of confinement centres (CCs) where mothers stay and receive traditional confinement care. Ethnic Chinese mothers have low breastfeeding rates. There are concerns that practices in CCs could contribute to this but no data exists. We described mothers' breastfeeding experiences at CCs and identified areas for potential improvement in breastfeeding support.

    METHODS: Ethnic Chinese mothers intending to breastfeed their healthy infants were recruited post-delivery between August and October 2017 then, at 1 and 6 months, they were telephone interviewed about their experience. For every participant going to a CC after the birth, another mother going home ("home") for her confinement was recruited. Chi-square test was used to compare groups and multiple logistic regression was used to assess the effect of confinement place on exclusive breastfeeding.

    RESULTS: Of 187 mothers, 88 (47%) went to CCs. Significantly more were primipara and fewer had previous breastfeeding experience. Response rates for the 1- and 6- month interviews were 88% (CC) versus 97% (home); and 77% (CC) versus 87% (home) respectively. Exclusive breastfeeding rates were similar between the groups: 62% (CC) versus 56% (home) at 1 month (p = 0.4); and 37% (CC) versus 42% (home) at 6 months (p = 0.5). Multiple logistic regression did not show that CCs were a factor affecting exclusive breastfeeding rates at 1 month, (adjusted odds ratio [aOR] 1.7, 95% confidence interval [CI] 0.9, 3.3), or 6 months (aOR 0.9, 95% CI 0.4, 1.7). However, significantly more CC participants only fed expressed breast milk. Despite 66% of CC participants reporting that their centre supported breastfeeding, only 6 (8%) CC participants compared to 66 (69%) of home participants roomed-in with their baby (p 

  14. Rohhimi W, Tan JW, Liew KY, Jacquet A, Harith HH, Israf DA, et al.
    PMID: 34694946 DOI: 10.1080/08923973.2021.1992633
    CONTEXT: The airway epithelial barrier can be disrupted by house dust mite (HDM) allergens leading to allergic airway inflammation. Zerumbone, a natural monocyclic sesquiterpene, was previously found to possess anti-asthmatic effect by modulating Th1/Th2 cytokines. However, the protective role of zerumbone on epithelial barrier function remains to be fully explored.

    OBJECTIVE: To investigate the effect of zerumbone on HDM extract-induced airway epithelial barrier dysfunction.

    MATERIALS AND METHODS: Human bronchial epithelial cells 16HBE14o- were incubated with 100 μg/mL HDM extract and treated with non-cytotoxic concentrations of zerumbone (6.25 μM, 12.5 μM, and 25 μM) for 24 h. The epithelial junctional integrity and permeability were evaluated through transepithelial electrical resistance (TEER) and fluorescein isothiocynate (FITC)-Dextran permeability assays, respectively. The localization of junctional proteins, occludin and zona occludens (ZO)-1, was studied using immunofluorescence (IF) while the protein expression was measured by western blot.

    RESULTS: Zerumbone inhibited changes in junctional integrity (6.25 μM, p ≤ .05; 12.5 μM, p ≤ .001; 25 μM, p ≤ .001) and permeability (6.25 μM, p ≤ .05; 12.5 μM, p ≤ .01; 25 μM, p ≤ .001) triggered by HDM extract in a concentration-dependent manner. This protective effect could be explained by the preservation of occludin (12.5 μM, p ≤ .01 and 25 μM, p ≤ .001) and ZO-1 (12.5 μM, p ≤ .05 and 25 μM, p ≤ .001) localization, rather than the prevention of their cleavage.

    DISCUSSION AND CONCLUSION: Zerumbone attenuates HDM extract-induced epithelial barrier dysfunction which supports its potential application for the treatment of inflammation-driven airway diseases such as asthma.

  15. Sukarna N, Tan PC, Hong JGS, Sulaiman S, Omar SZ
    Arch Gynecol Obstet, 2021 08;304(2):345-353.
    PMID: 33452923 DOI: 10.1007/s00404-020-05950-3
    PURPOSE: To compare 3 consecutive days of hyperglycemic response following antenatal dexamethasone regimens of 12-mg or 6-mg doses 12 hourly in diet-controlled gestational diabetes.

    METHODS: A randomized controlled trial was carried out in a university hospital in Malaysia. Women with lifestyle-controlled gestational diabetes scheduled to receive clinically indicated antenatal corticosteroids (dexamethasone) were randomized to 12-mg 12 hourly for one day (2 × 12-mg) or 6-mg 12-hourly for two days (4 × 6-mg). 6-point (pre and 2-h postprandial) daily self-monitoring of capillary blood sugar profile for up to 3 consecutive days was started after the first dexamethasone injection. Hyperglycemia is defined as blood glucose pre-meal ≥ 5.3 or 2 h postprandial ≥ 6.7 mmol/L. The primary outcome was a number of hyperglycemic episodes in Day-1 (first 6 BSP points). A sample size of 30 per group (N = 60) was planned.

    RESULTS: Median [interquartile range] hyperglycemic episodes 4 [2.5-5] vs. 4 [3-5] p = 0.3 in the first day, 3 [2-4] vs. 1 [0-3] p = 0.01 on the second day, 0 [0-1] vs. 0 [0-1] p = 0.6 on the third day and over the entire 3 trial days 7 [6-9] vs. 6 [4-8] p = 0.17 for 6-mg vs. 12-mg arms, respectively. 2/30 (7%) in each arm received an anti-glycemic agent during the 3-day trial period (capillary glucose exceeded 11 mmol/L). Mean birth weight (2.89 vs. 2.49 kg p 

  16. Liew YJM, Lee YK, Khalid N, Rahman NA, Tan BC
    Mol Biotechnol, 2021 Apr;63(4):316-326.
    PMID: 33565047 DOI: 10.1007/s12033-021-00304-z
    Prenylation of aromatic natural products by membrane-bound prenyltransferases (PTs) is an important biosynthesis step of many bioactive compounds. At present, only a few plant flavonoid-related PT genes have been functionally characterized, mainly due to the difficulties of expressing these membrane proteins. Rapid and effective methods to produce functional plant membrane proteins are thus indispensable. Here, we evaluated expression systems through cell-based and cell-free approaches to express Boesenbergia rotunda BrPT2 encoding a membrane-bound prenyltransferase. We attempted to express BrPT2 in Escherichia coli and tobacco plants but failed to detect this protein using the Western-blot technique, whereas an intact single band of 43 kDa was detected when BrPT2 was expressed using a cell-free protein synthesis system (PURE). Under in vitro enzymatic condition, the synthesized BrPT2 successfully catalyzed pinostrobin chalcone to pinostrobin. Molecular docking analysis showed that pinostrobin chalcone interacts with BrPT2 at two cavities: (1) the main binding site at the central cavity and (2) the allosteric binding site located away from the central cavity. Our findings suggest that cell-free protein synthesis could be an alternative for rapid production of valuable difficult-to-express membrane proteins.
  17. Yap JKY, Tan SYY, Tang SQ, Thien VK, Chan EWL
    Microb Drug Resist, 2021 Feb;27(2):234-240.
    PMID: 32589487 DOI: 10.1089/mdr.2020.0178
    Aims: Currently, limited antibiotics are available to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. One approach is the use of adjuvants in antibiotic therapy. 1,4-Naphthoquinones are naturally occurring alkaloids shown to have antibacterial properties. The objective of this study is to investigate the synergy between 1,4-naphthoquinone and selected β-lactam antibiotics and to evaluate the potential use of 1,4-naphthoquinone as an adjuvant in antibiotic treatment against MRSA infections. Methods: The antibacterial activity of 1,4-naphthoquinone and plumbagin was tested against nine pathogenic bacterial strains using the microdilution broth method. The interactions between 1,4-naphthoquinone and three antibiotics (cefuroxime, cefotaxime, and imipenem) were estimated by calculating the fractional inhibitory concentration of the combination. Results: The compounds 1,4-naphthoquinone and plumbagin exhibited a broad range of bacteriostatic and bactericidal effects against both Gram-positive and Gram-negative bacteria. The interaction between 1,4-naphthoquinone and imipenem, cefuroxime, and cefotaxime was synergistic against methicillin-sensitive Staphylococcus aureus and MRSA clinical strains. Against ATCC-cultured MRSA, a synergistic effect was observed between 1,4-naphthoquinone and cefotaxime. However, combination with imipenem only produced an additive effect, and an antagonistic action was observed between 1,4-naphthoquinone and cefuroxime. Conclusions: Although individually less potent than common antibiotics, 1,4-naphthoquinone acts synergistically with imipenem, cefuroxime, and cefotaxime against MRSA clinical strains and could potentially be used in adjuvant-antibiotic therapy against multidrug resistant bacteria.
  18. Lau TV, Puah SM, Tan JMA, Puthucheary SD, Chua KH
    Braz J Microbiol, 2021 Jun;52(2):517-529.
    PMID: 33768508 DOI: 10.1007/s42770-021-00457-8
    Flagellar-mediated motility is a crucial virulence factor in many bacterial species. A dual flagellar system has been described in aeromonads; however, there is no flagella-related study in the emergent human pathogen Aeromonas dhakensis. Using 46 clinical A. dhakensis, phenotypic motility, genotypic characteristics (flagellar genes and sequence types), biochemical properties and their relationship were investigated in this study. All 46 strains showed swimming motility at 30 °C in 0.3% Bacto agar and carried the most prevalent 6 polar flagellar genes cheA, flgE, flgG, flgH, flgL, and flgN. On the contrary, only 18 strains (39%) demonstrated swarming motility on 0.5% Eiken agar at 30 °C and they harbored 11 lateral flagellar genes lafB, lafK, lafS, lafT, lafU, flgCL, flgGL, flgNL, fliEL, fliFL, and fliGL. No association was found between biochemical properties and motility phenotypes. Interestingly, a significant association between swarming and strains isolated from pus was observed (p = 0.0171). Three strains 187, 277, and 289 isolated from pus belonged to novel sequence types (ST522 and ST524) exhibited fast swimming and swarming profiles, and they harbored > 90% of the flagellar genes tested. Our findings provide a fundamental understanding of flagellar-mediated motility in A. dhakensis.
  19. Tan HJ, Tee TY, Husin M, Khoo CS, Woon LS
    Epileptic Disord, 2020 Dec 01;22(6):828-833.
    PMID: 33337333 DOI: 10.1684/epd.2020.1233
    Super-refractory status epilepticus (SRSE) is a neurocritical emergency, associated with significant morbidity and mortality. The precise pathophysiology is still not completely understood. The likelihood of spontaneous seizure termination reduces with time, and it is of paramount importance to abort status in order to prevent permanent long-term neurological sequelae and death. A few neuroprotective strategies, such as general anaesthesia, steroids, ketogenic diet and hypothermia, have been used to treat SRSE, however, the clinical outcome remains inconclusive. We herein present two cases of SRSE, which were successfully treated with electroconvulsive therapy (ECT) after failing all pharmacological measures.
  20. Tan CS, Hamzah ND, Ismail ZHF, Jerip AR, Kipli M
    Med J Malaysia, 2021 05;76(3):298-303.
    PMID: 34031326
    INTRODUCTION: Cervical cancer is the third most common cancer among Malaysian women. Sarawak, the largest state in Malaysia has consistently recorded the highest cervical cancer rate in the country where nearly half of its population still live in the rural areas and is at increased risk of the disease due to inequitable access to healthcare. The countrywide lockdown due to the COVID-19 pandemic had halted the accessibility to cervical cancer screening programme. The aim of the study is to determine the feasibility of providing primary HPV DNA test using the selfsampling method to the hard-to-reach population in the interior of Sarawak during the COVID-19 pandemic.

    MATERIALS AND METHODS: This is a cross-sectional study where women aged between 20-80 years were recruited via convenient sampling from villages in Long Banga, Sarawak over a five-day outreach programme. Cervicovaginal selfsamples were obtained and screened for the presence of high-risk human papillomavirus DNA (HR-HPV) using the careHPVTM Test. A self-administered questionnaire was also administered to determine the sociodemographic and perception towards the self-sampling method.

    RESULTS: The 55 women recruited consist of ethnic backgrounds of Penan (58.18%), Kenyah (25.45%), Iban (5.45%), Saban (3.64%), Kelabit (3.64%), Malay (1.82%) and Chinese (1.82%). The prevalence of HR-HPV was 1.85% (n=1/55). Nearly 80% of the women were unemployed, and more than half have had attended primary education. Nine (16.4%) have heard about HPV, and seven (13%) knew HPV infection could cause cervical cancer. Three of them had HPV vaccination, and only one (1.85%) knew the brand of the HPV vaccine. Although 40% preferred self-sampling over clinician-collection, only ten (18.2%) women have completed the self-collection perception questionnaire.

    CONCLUSION: Primary HPV DNA screening using the selfsampling method can be carried out in the remote areas during the COVID-19 pandemic without compromising mobility restriction.

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