Displaying publications 41 - 60 of 139 in total

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  1. Fulltext European polygenic risk score for prediction of breast cancer shows similar performance in Asian women
    Ho WK, Tan MM, Mavaddat N, Tai MC, Mariapun S, Li J, et al.
    Nat Commun, 2020 07 31;11(1):3833.
    PMID: 32737321 DOI: 10.1038/s41467-020-17680-w
    Polygenic risk scores (PRS) have been shown to predict breast cancer risk in European women, but their utility in Asian women is unclear. Here we evaluate the best performing PRSs for European-ancestry women using data from 17,262 breast cancer cases and 17,695 controls of Asian ancestry from 13 case-control studies, and 10,255 Chinese women from a prospective cohort (413 incident breast cancers). Compared to women in the middle quintile of the risk distribution, women in the highest 1% of PRS distribution have a ~2.7-fold risk and women in the lowest 1% of PRS distribution has ~0.4-fold risk of developing breast cancer. There is no evidence of heterogeneity in PRS performance in Chinese, Malay and Indian women. A PRS developed for European-ancestry women is also predictive of breast cancer risk in Asian women and can help in developing risk-stratified screening programmes in Asia.
  2. Fulltext Malaysian macroalga Padina australis Hauck attenuates high dose corticosterone-mediated oxidative damage in PC12 cells mimicking the effects of depression
    Subermaniam K, Yow YY, Lim SH, Koh OH, Wong KH
    Saudi J Biol Sci, 2020 Jun;27(6):1435-1445.
    PMID: 32489279 DOI: 10.1016/j.sjbs.2020.04.042
    Oxidative damage has been associated with the pathophysiology of depression. Macroalgae are equipped with antioxidant defense system to counteract the effects of free radicals. We explored the use of Malaysian Padina australis to attenuate high dose corticosterone-mediated oxidative damage in a cellular model mimicking depression. Fresh specimen of P. australis was freeze-dried and extracted sequentially with hexanes, ethyl acetate and ethanol. The extracts were screened for their phytochemical contents and antioxidant activities. Ethanol extract demonstrated the most potent antioxidant capacity and was selected for subsequent assays against high dose corticosterone of 600 µM-mediated oxidative damage in the rat pheochromocytoma (PC12) cells. The corticosterone reduced the cell viability, glutathione (GSH) level, aconitase activity, and mitochondrial membrane potential (MMP); and increased the lactate dehydrogenase (LDH) release, intracellular reactive oxygen species (ROS) level and apoptosis. However, the extent of oxidative damage was reversed by 0.25-0.5 mg/mL ethanol extract suggesting a possible role of P. australis-based antioxidants in the mitochondrial defense against constant ROS generation and regulation of antioxidant pathway. The effects were similar to that of desipramine, a tricyclic antidepressant. Our findings indicate that P. australis can be developed as a mitochondria-targeted antioxidant to mitigate antidepressant-like effects.
  3. Association of co-occurring psychosocial health conditions and HIV infection among MSM in Malaysia: Implication of a syndemic effect
    Ng RX, Guadamuz TE, Akbar M, Kamarulzaman A, Lim SH
    Int J STD AIDS, 2020 05;31(6):568-578.
    PMID: 32299293 DOI: 10.1177/0956462420913444
  4. Fulltext Use of Smartphone to Seek Sexual Health Information Online Among Malaysian Men Who Have Sex with Men (MSM): Implications for mHealth Intervention to Increase HIV Testing and Reduce HIV Risks
    Shrestha R, Lim SH, Altice FL, Copenhaver M, Wickersham JA, Saifi R, et al.
    J Community Health, 2020 02;45(1):10-19.
    PMID: 31375976 DOI: 10.1007/s10900-019-00713-x
    In settings where stigma and discrimination toward men who have sex with men (MSM) are high or illegal, like in Malaysia, innovative methods to anonymously reach them are urgently needed. The near ubiquitous availability of mobile technology, including smartphones, has the potential to open new frontiers (such as mHealth) to prevent HIV and other sexually transmitted infections (STIs). The extent to which MSM use mHealth tools for HIV and STI prevention in the Malaysia context, however, is unknown. A cross-sectional online survey in 622 Malaysian MSM was conducted between July and November 2017. Participants were recruited via advertisements on mobile apps frequently used by MSM. In addition to demographic, smartphone access and utilization, and other information were assessed using logistic regression to determine factors associated with the use of a smartphone to search for online sexual health information. Nearly all (99.2%) participants owned a smartphone, with 63% reported having used one to seek sexual health information, including HIV/STIs. Overall, 96% used smartphones to find sexual partners, with high levels of HIV risk behavior reported. Independent correlates of smartphone use to seek online sexual health information included older age (aOR 0.943, p = 0.005), higher education (aOR 2.14, p = 027), recent (past year) HIV testing (aOR 3.91, p = 0.026), and seeking sexual partners using geosocial networking apps (aOR 5.58, p = 0.006). These findings suggest high smartphone use by high-risk MSM to seek sexual health information and suggests that mHealth strategies may be an effective strategy to engage MSM in HIV prevention activities.
  5. Fulltext Lavender essential oil induces oxidative stress which modifies the bacterial membrane permeability of carbapenemase producing Klebsiella pneumoniae
    Yang SK, Yusoff K, Thomas W, Akseer R, Alhosani MS, Abushelaibi A, et al.
    Sci Rep, 2020 01 21;10(1):819.
    PMID: 31964900 DOI: 10.1038/s41598-019-55601-0
    Misuse of antibiotics in the clinical and agricultural sectors has caused the emergence of multidrug-resistant (MDR) Klebsiella pneumoniae which contributes a threat to human health. In this study, we assessed the feasibility of lavender essential oil (LVO) as an antimicrobial agent in combinatory therapy with meropenem in suppressing the growth of carbapenemase-producing K. pneumoniae (KPC-KP). Synergistic interactions between LVO and meropenem were detected, which significantly reduce the inhibitory concentration of both LVO and meropenem by 15 and 4-fold respectively. Comparative proteomic profiling identified a disruption in the bacterial membrane via oxidative stress that was indicated by loss of membrane and cytoplasmic proteins and the upregulation of oxidative regulators. As a proof of concept, zeta potential measurements showed a change in cell surface charge while outer membrane permeability measurement indicated an increase in membrane permeability following exposure to LVO. This was indicative of a disrupted outer membrane. Ethidium bromide influx/efflux assays demonstrated no significant efflux pump inhibition by LVO, and scanning electron microscopy revealed irregularities on the cell surface after exposure to LVO. Oxidative stress was also detected with increased level of ROS and lipid peroxidation in LVO-treated cells. In conclusion, our data suggest that LVO induced oxidative stress in K. pneumoniae which oxidizes the outer membrane, enabling the influx of generated ROS, LVO and meropenem into the bacterial cells, causing damage to the cells and eventually death.
  6. Fulltext Outcomes of HIV treatment from the private sector in low-income and middle-income countries: a systematic review protocol
    Mburu G, Igbinedion E, Lim SH, Paing AZ, Yi S, Elbe S, et al.
    BMJ Open, 2020 Jan 08;10(1):e031844.
    PMID: 31919124 DOI: 10.1136/bmjopen-2019-031844
    INTRODUCTION: Private sector provision of HIV treatment is increasing in low-income and middle-income countries (LMIC). However, there is limited documentation of its outcomes. This protocol reports a proposed systematic review that will synthesise clinical outcomes of private sector HIV treatment in LMIC.

    METHODS AND ANALYSIS: This review will be conducted in accordance with the preferred reporting items for systematic review and meta-analyses protocols. Primary outcomes will include: (1) proportion of eligible patients initiating antiretroviral therapy (ART); (2) proportion of those on ART with <1000 copies/mL; (3) rate of all-cause mortality among ART recipients. Secondary outcomes will include: (1) proportion receiving Pneumocystis jiroveci pneumonia prophylaxis; (2) proportion with >90% ART adherence (based on any measure reported); (3) proportion screened for non-communicable diseases (specifically cervical cancer, diabetes, hypertension and mental ill health); (iv) proportion screened for tuberculosis. A search of five electronic bibliographical databases (Embase, Medline, PsychINFO, Web of Science and CINAHL) and reference lists of included articles will be conducted to identify relevant articles reporting HIV clinical outcomes. Searches will be limited to LMIC. No age, publication date, study-design or language limits will be applied. Authors of relevant studies will be contacted for clarification. Two reviewers will independently screen citations and abstracts, identify full text articles for inclusion, extract data and appraise the quality and bias of included studies. Outcome data will be pooled to generate aggregative proportions of primary and secondary outcomes. Descriptive statistics and a narrative synthesis will be presented. Heterogeneity and sensitivity assessments will be conducted to aid interpretation of results.

    ETHICS AND DISSEMINATION: The results of this review will be disseminated through a peer-reviewed scientific manuscript and at international scientific conferences. Results will inform quality improvement strategies, replication of identified good practices, potential policy changes, and future research.

    PROSPERO REGISTRATION NUMBER: CRD42016040053.

  7. Discovering the Potentials of Medicinal Mushrooms in Combating Depression - A Review
    Lew SY, Teoh SL, Lim SH, Lim LW, Wong KH
    Mini Rev Med Chem, 2020;20(15):1518-1531.
    PMID: 32452327 DOI: 10.2174/1389557520666200526125534
    Depression is the most common form of mental illness and the major cause of disability worldwide. Symptoms of depression, including feelings of intense sadness and hopelessness, may occur after a specific event or in response to a gradual decline in health and functional status, often associated with aging. Current therapies for treating these symptoms include antidepressant drugs, counseling and behavioral therapy. However, antidepressant drugs are associated with mild to severe adverse effects, which has prompted the need for better treatment options. Medicinal mushrooms are valuable sources of food and medicine and are increasingly being used as supplements or as alternative medicines in standard healthcare. Numerous studies have provided insights into the neuroprotective effects of medicinal mushrooms, which are attributed to their antioxidant, anti-neuroinflammatory, cholinesterase inhibitory and neuroprotective properties. In this review, we comprehensively examine the role of these medicinal mushrooms in the treatment of depression. However, to apply these natural products in clinical settings, the therapeutic agent needs to be properly evaluated, including the active ingredients, the presence of synergistic effects, efficient extraction methods, and stabilization of the active ingredients for delivery into the body as well as crossing the blood-brain barrier.
  8. Mechanisms of Antimicrobial Resistance (AMR) and Alternative Approaches to Overcome AMR
    Moo CL, Yang SK, Yusoff K, Ajat M, Thomas W, Abushelaibi A, et al.
    Curr Drug Discov Technol, 2020;17(4):430-447.
    PMID: 30836923 DOI: 10.2174/1570163816666190304122219
    Antimicrobials are useful compounds intended to eradicate or stop the growth of harmful microorganisms. The sustained increase in the rates of antimicrobial resistance (AMR) worldwide is worrying and poses a major public health threat. The development of new antimicrobial agents is one of the critical approaches to overcome AMR. However, in the race towards developing alternative approaches to combat AMR, it appears that the scientific community is falling behind when pitched against the evolutionary capacity of multi-drug resistant (MDR) bacteria. Although the "pioneering strategy" of discovering completely new drugs is a rational approach, the time and effort taken are considerable, the process of drug development could instead be expedited if efforts were concentrated on enhancing the efficacy of existing antimicrobials through: combination therapies; bacteriophage therapy; antimicrobial adjuvants therapy or the application of nanotechnology. This review will briefly detail the causes and mechanisms of AMR as background, and then provide insights into a novel, future emerging or evolving strategies that are currently being evaluated and which may be developed in the future to tackle the progression of AMR.
  9. Fulltext Willingness to Use HIV Self-Testing and Associated Factors Among Transgender Women in Malaysia
    Shrestha R, Galka JM, Azwa I, Lim SH, Guadamuz TE, Altice FL, et al.
    Transgend Health, 2020;5(3):182-190.
    PMID: 32923668 DOI: 10.1089/trgh.2019.0085
    Background: While global research on the implementation of HIV self-testing (HIVST) has increased exponentially, few studies have assessed information on HIVST uptake factors (i.e., willingness, preferences) in transgender women (TW) and none in the Malaysian context. We therefore sought to assess willingness to use HIVST among this understudied key population. Methods: A cross-sectional survey was conducted among 361 HIV-negative Malaysian TW in 2017. Participants were recruited using flyers, announcements through social media, and direct referral from staff members of the community-based organizations serving the TW communities. Multivariable logistic regression was used to identify correlates of willingness to use HIVST. Results: Nearly half of the participants (47.6%) reported that they would be willing to use HIVST. Multivariable analysis showed that willingness to use HIVST was positively associated with having experienced sexual assault in childhood (adjusted odds ratio [aOR]=3.239, p<0.001), having ever used mobile phone or apps to find sex work clients (aOR=1.677, p=0.040), and having engaged in condomless sex in the past 6 months (aOR=1.886, p=0.018). In contrast, living in Kuala Lumpur (aOR=0.559, p=0.032), having higher number of sex work clients per day (aOR=0.927, p=0.004), and current depressive symptoms (aOR=0.576, p=0.026) were negatively associated with willingness to use HIVST. Conclusions: Findings in this study suggest that TW in our sample were moderately willing to use HIVST. Especially important here is the increased interest in HIVST among TW who are at higher risk for HIV infection. Overall, our findings underscore the need for additional research on how to most effectively implement HIVST for key populations, including TW, such that uptake and retention in regular HIV screening is sustained.
  10. "You Have to Keep Yourself Hidden": Perspectives From Malaysian Malay-Muslim Men Who Have Sex With Men on Policy, Network, Community, and Individual Influences on HIV Risk
    Lim SH, Brown SE, Shaw SA, Kamarulzaman A, Altice FL, Beyrer C
    J Homosex, 2020;67(1):104-126.
    PMID: 30307803 DOI: 10.1080/00918369.2018.1525946
    Malay-Muslim men who have sex with men (MSM) are marginalized and hidden in Malaysia, a predominantly Muslim country in southeast Asia. We explored the policy, network, community, and individual factors related to HIV infection among Malay-Muslim MSM through 26 in-depth interviews and one focus group discussion (n = 5) conducted in Kuala Lumpur and Kota Bharu between October 2013 and January 2014. As religion plays an important role in their lives, participants viewed homosexuality as a sin. Low risk perception and misconceptions about HIV/AIDS were common, and most participants expressed reluctance to consult a doctor unless they had symptoms. Additionally, buying condoms was embarrassing and anxiety-producing. Fear of discrimination by health care providers and community hindered participants from disclosing sexual behaviors and accessing health services. Homophobic comments and policies by the government and religious leaders were concerns of participants. A safe and enabling environment is needed to reduce HIV risks among Malay-Muslim MSM.
  11. Fulltext Mutations in the tail domain of MYH3 contributes to atrial septal defect
    Maran S, Ee R, Faten SA, Sy Bing C, Khaw KY, Erin Lim SH, et al.
    PLoS One, 2020;15(4):e0230982.
    PMID: 32315303 DOI: 10.1371/journal.pone.0230982
    Atrial septal defect (ASD) is one of the most common congenital heart defects diagnosed in children. Sarcomeric genes has been attributed to ASD and knockdown of MYH3 functionally homologues gene in chick models indicated abnormal atrial septal development. Here, we report for the first time, a case-control study investigating the role of MYH3 among non-syndromic ASD patients in contributing to septal development. Four amplicons which will amplifies the 40 kb MYH3 were designed and amplified using long range-PCR. The amplicons were then sequenced using indexed paired-end libraries on the MiSeq platform. The STREGA guidelines were applied for planning and reporting. The non-synonymous c. 3574G>A (p.Ala1192Thr) [p = 0.001, OR = 2.30 (1.36-3.87)] located within the tail domain indicated a highly conserved protein region. The mutant model of c. 3574G>A (p.Ala1192Thr) showed high root mean square deviation (RMSD) values compared to the wild model. To our knowledge, this is the first study to provide compelling evidence on the pathogenesis of MYH3 variants towards ASD hence, suggesting the crucial role of non-synonymous variants in the tail domain of MYH3 towards atrial septal development. It is hoped that this gene can be used as panel for diagnosis of ASD in future.
  12. Fulltext Antibacterial Activity and Mode of Action of β-caryophyllene on Bacillus cereus
    Moo CL, Yang SK, Osman MA, Yuswan MH, Loh JY, Lim WM, et al.
    Pol J Microbiol, 2020;69:1-6.
    PMID: 32162852 DOI: 10.33073/pjm-2020-007
    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to -3.98 mV, compared to untreated cells (-5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to –3.98 mV, compared to untreated cells (–5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

  13. A 5-year retrospective study of melioidosis cases treated in a district specialist hospital
    Tang RY, Lim SH, Lam JE, Nurasykin S, Eileen T, Chan YW
    Med J Malaysia, 2019 12;74(6):472-476.
    PMID: 31929471
    INTRODUCTION: Melioidosis is caused by Burkholderia pseudomallei, a gram-negative aerobic bacillus, found in the soil and surface water. Treating melioidosis has been a challenge in district hospitals due to high usage of broad spectrum antibiotics and prolonged hospitalisation. This study is to review the patients' demography, clinical presentations and microbiological data.

    METHODS: A 5-year retrospective study was carried out on patients admitted with culture positive for melioidosis from year 2013 to 2017 in Hospital Teluk Intan, Perak.

    RESULTS: There were a total of 46 confirmed cases of melioidosis. Majority of the patients were working in the agricultural and farming (28.6%), and factories (25.7%). Thirty-one patients had diabetes mellitus (71.1%). Presentations of patients with melioidosis included pneumonia (54.3%), skin and soft tissue infection (19.6%), deep abscesses (15.2%) and bone and joint infections (13%). An average of 5.8 days was needed to confirm the diagnosis of melioidosis via positive culture. However, only 39.4% of these patients were started on ceftazidime or carbapenem as the empirical therapy. The intensive care unit (ICU) admission rate for melioidosis was 46% and the mortality rate was 52%. Our microbial cultures showed good sensitivity towards cotrimoxazole (97.1%), ceftazidime (100%) and carbapenem (100%).

    CONCLUSION: Melioidosis carries high mortality rate, especially with lung involvement and bacteremia. Physicians should have high clinical suspicion for melioidosis cases to give appropriate antimelioidosis therapy early.

  14. Macroline-Sarpagine Bisindole Alkaloids with Antiproliferative Activity from Alstonia penangiana
    Yeap JS, Saad HM, Tan CH, Sim KS, Lim SH, Low YY, et al.
    J Nat Prod, 2019 11 22;82(11):3121-3132.
    PMID: 31642315 DOI: 10.1021/acs.jnatprod.9b00712
    A methanol extract of the stem bark of the Malayan Alstonia penangiana provided seven new bisindole alkaloids, comprising six macroline-sarpagine alkaloids (angustilongines E-K, 1-6) and one macroline-pleiocarpamine bisindole alkaloid (angustilongine L, 7). Analysis of the spectroscopic data (NMR and MS) of these compounds led to the proposed structures of these alkaloids. The macroline-sarpagine alkaloids (1-6) showed in vitro growth inhibitory activity against a panel of human cancer cell lines, inclusive of KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells (IC50 values: 0.02-9.0 μM).
  15. Factors influencing patients' hypertension self-management and sustainable self-care practices: a qualitative study
    M Yatim H, Wong YY, Neoh CF, Lim SH, Hassali MA, Hong YH
    Public Health, 2019 Aug;173:5-8.
    PMID: 31207425 DOI: 10.1016/j.puhe.2019.04.020
    OBJECTIVE: The objective of this study was to explore factors influencing patients with hypertension to participating in a hypertension self-management education (HSME) programme and challenges of sustaining the learnt self-care practices.

    STUDY DESIGN: This was a qualitative study with focus group discussions.

    METHODS: Focus group discussions using a semistructured moderator guide were conducted among participants who had attended the HSME programme. Data were audio recorded, transcribed verbatim and analysed using a thematic analysis approach.

    RESULTS: Three focus groups involving 19 participants were conducted. Four major themes emerged from the data collected. Most participants enjoyed the group-based HSME sessions because sharing experiences with those having similar health problems can reduce their sense of isolation. However, the participants highlighted the difficulty in sustaining self-care practices in the presence of friends and family influences.

    CONCLUSION: A number of patient-, family- and community-level motivators and barriers to patients' hypertension self-management have been identified. Efforts to tailor behavioural interventions to sustain daily self-care activities during social and cultural events are imperative.
  16. A Cytotoxic Indole Characterized by Incorporation of a Unique Carbon-Nitrogen Skeleton and Two Pentacyclic Corynanthean Alkaloids Incorporating a Substituted Tetrahydrofuranone Ring from Kopsia arborea
    Wong SK, Wong SP, Sim KS, Lim SH, Low YY, Kam TS
    J Nat Prod, 2019 07 26;82(7):1902-1907.
    PMID: 31241923 DOI: 10.1021/acs.jnatprod.9b00255
    Three new alkaloids were isolated from the bark extract of the Malayan Kopsia arborea, viz., arbophyllidine (1), an unusual pentacyclic, monoterpenoid indole characterized by an absence of oxygen atoms and incorporating a new carbon-nitrogen skeleton, and arbophyllinines A (2) and B (3), two pentacyclic corynanthean alkaloids incorporating a hydroxyethyl-substituted tetrahydrofuranone ring. The structures of the alkaloids were deduced based on analysis of the MS and NMR data and confirmed by X-ray diffraction analyses. The absolute configuration of arbophyllidine (1) was established based on experimental and calculated ECD data, while that of arbophyllinine A was based on X-ray diffraction analysis (Cu Kα). A reasonable biosynthetic route to arbophyllidine (1) from a pericine precursor is presented. Arbophyllidine (1) showed pronounced in vitro growth inhibitory activity against the HT-29 human cancer cell line with IC50 6.2 μM.
  17. A Qualitative Study of HIV "Test-and-Treat" Experience Among Men Who Have Sex With Men in Malaysia
    Lim SH, Alias H, Kien JKW, Akbar M, Kamarulzaman A, Wong LP
    AIDS Educ Prev, 2019 06;31(3):193-205.
    PMID: 31145000 DOI: 10.1521/aeap.2019.31.3.193
    This study aimed to examine the barriers and facilitators to HIV testing and treatment among Malaysian MSM. Between June 2014 and December 2015, in-depth interviews were conducted in 20 HIV-positive MSM recruited from a teaching hospital and NGO in Kuala Lumpur. Thematic analysis was used to identify, analyze, and report themes. Most participants investigated their HIV status after long period of sickness. Others sought testing upon partner's diagnosis and some were diagnosed via blood donation. Barriers to testing include personal (perceived good health, fear of positive result, denial); social and structural factors (stigmatization by health providers and family, lack of information about free HIV testing and long wait time). Barriers to treatment comprise personal factors (perceived HIV as incurable and treatment as complicated), social factors (HIV and homosexual stigma), and cost. Promoting benefits of regular testing and early treatment is needed to improve HIV care continuum among MSM in Malaysia.
  18. Conolodinines A-D, Aspidosperma- Aspidosperma Bisindole Alkaloids with Antiproliferative Activity from Tabernaemontana corymbosa
    Sim DS, Navanesan S, Sim KS, Gurusamy S, Lim SH, Low YY, et al.
    J Nat Prod, 2019 04 26;82(4):850-858.
    PMID: 30869890 DOI: 10.1021/acs.jnatprod.8b00919
    Examination of the EtOH extract of the leaves of the Malayan Tabernaemontana corymbosa resulted in the isolation of four new (1-4) and two known bisindole alkaloids (5, 6) of the Aspidosperma- Aspidosperma type. The structures of these alkaloids were determined based on analysis of the spectroscopic data (NMR and HRESIMS). X-ray diffraction analyses of the related bisindole alkaloids conophylline (5) and conophyllinine (6) established the absolute configurations. Treatment of the bisindole alkaloid conophylline (5) with benzeneselenic anhydride gave, in addition to the known bisindole polyervinine (7) previously isolated from another Malayan Tabernaemontana, another bisindole product, 8, an isolable tautomer of 7. X-ray diffraction analyses yielded the absolute configurations of both bisindoles and in addition showed that polyervinine (7) exists primarily as the neutral dione structure. The bisindoles (1-8) and the related conophylline-type bisindoles (9-13) showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, A549, HT-29, and HCT 116 cells, with IC50 values for the active compounds in the 0.01-5 μM range.
  19. Lycopodium Alkaloids: Lycoplatyrine A, an Unusual Lycodine-Piperidine Adduct from Lycopodium platyrhizoma and the Absolute Configurations of Lycoplanine D and Lycogladine H
    Yeap JS, Lim KH, Yong KT, Lim SH, Kam TS, Low YY
    J Nat Prod, 2019 02 22;82(2):324-329.
    PMID: 30698428 DOI: 10.1021/acs.jnatprod.8b00754
    Three new Lycopodium alkaloids comprising two lycodine-type alkaloids (1, 2) and one fawcettimine alkaloid (3), in addition to 16 known alkaloids, were isolated from Lycopodium platyrhizoma. The structures of these alkaloids were elucidated based on analysis of their NMR and MS data. Lycoplatyrine A (1) represents an unusual lycodine-piperidine adduct. The structures and absolute configurations of lycoplanine D (hydroxy-des- N-methyl-α-obscurine, 10) and lycogladine H (11) were confirmed by X-ray diffraction analysis.
  20. Alstoscholactine and Alstolaxepine, Monoterpenoid Indole Alkaloids with γ-Lactone-Bridged Cycloheptane and Oxepane Moieties from Alstonia scholaris
    Krishnan P, Lee FK, Chong KW, Mai CW, Muhamad A, Lim SH, et al.
    Org. Lett., 2018 12 21;20(24):8014-8018.
    PMID: 30543301 DOI: 10.1021/acs.orglett.8b03592
    Two new monoterpenoid indole alkaloids, alstoscholactine (1) and alstolaxepine (2), were isolated from Alstonia scholaris. Compound 1 represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, whereas compound 2 represents a 6,7- seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. Their structures and absolute configurations were determined by spectroscopic analyses. Compound 1 was successfully semisynthesized from 19 E-vallesamine. Compound 2 induced marked vasorelaxation in rat isolated aortic rings precontracted with phenylephrine.
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