Displaying publications 21 - 40 of 45 in total

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  1. Ariffin H, Lum SH, Cheok SA, Shekhar K, Ariffin WA, Chan LL, et al.
    J Paediatr Child Health, 2005 Mar;41(3):136-9.
    PMID: 15790325
    To study the clinical presentation, therapy and outcome of children diagnosed with both primary and secondary haemophagocytic lymphohistiocytosis (HLH) at the University of Malaya Medical Centre.
  2. Ng SM, Lin HP, Ariffin WA, Zainab AK, Lam SK, Chan LL
    J Trop Pediatr, 2000 Dec;46(6):338-43.
    PMID: 11191144
    The presenting features and treatment outcome for 575 Malaysian children (< or = 12 years of age) with newly diagnosed acute lymphoblastic leukemia (ALL), admitted to the University Hospital, Kuala Lumpur, Malaysia between 1 January 1980 and 30 May 1995 were evaluated to determine their prognostic significance. Two-year overall survival was achieved in 67 per cent of all patients and 55 per cent of patients were relapse-free at 2 years. All except 10 patients, with identified French-American-British L3 morphology were treated with the modified Berlin-Frankfurt-Munster 78 treatment protocol. Univariate analyses of failure rate conferred age, sex, white cell count and hemoglobin level as potentially significant prognostic factors. All four presenting features retained their prognostic strength in a multivariate analysis. Race, platelet count, morphological subtype, liver/spleen size, lymphadenopathy, central nervous system and mediastinal mass involvement did not show any significant effect on treatment outcome. The 2-year survival rate was significantly different with regard to age, white cell count and hemoglobin level. However, sex was not significantly related to overall survival. These prognostic factors may have implications on future stratification of risk-adjusted initial treatment in the management of childhood ALL. Our analysis of Malaysian children is similar to what could be predicted based on previous studies in other populations.
  3. Thong MK, Rudzki Z, Hall J, Tan JA, Chan LL, Yap SF
    Hum Mutat, 1999;13(5):413.
    PMID: 10338100 DOI: 10.1002/(SICI)1098-1004(1999)13:5<413::AID-HUMU15>
    Beta-thalassemia major is one of the commonest genetic disorders in South-East Asia. The spectrum of beta-thalassemia mutations in the various ethnic sub-populations on the island of Borneo is unknown. We studied 20 Dusun children from the East Malaysian state of Sabah (North Borneo) with a severe beta-thalassemia major phenotype, using a combination of Southern analysis, polymerase chain reaction analysis and direct sequencing. We found the children to be homozygous for a large deletion, which has a 5' breakpoint at position -4279 from the cap site of the beta-globin gene (HBB) with the 3' breakpoint located in a L1 family of repetitive sequences at an unknown distance from the beta-globin gene. This was similar to a recent finding of a large deletion causing beta-thalassemia first described in unrelated beta-thalassemia heterozygotes of Filipino descent. This report describes the first 20 families with homozygosity of the deletion causing a severe phenotype. It provides the first information on the molecular epidemiology of beta-thalassemia in Sabah. This finding has implications for the population genetics and preventative strategies for beta-thalassemia major for nearly 300 million individuals in South-East Asia.
  4. Ng SM, Ariffin WA, Lin HP, Chan LL, Chin YM
    J Trop Pediatr, 2000 Apr;46(2):73-8.
    PMID: 10822932
    The purpose of the study was to evaluate the incidence of myeloid antigen coexpression and its prognostic significance in childhood acute lymphoblastic leukemia (ALL) in Malaysia. A retrospective study was conducted of all ALL cases (< or = 12 years old) diagnosed and treated in University Hospital, Kuala Lumpur, Malaysia between 1 January 1992 and 30 May 1995, with available immunophenotype data. Presenting features and treatment outcome of 39 B-lineage ALL patients with myeloid antigen coexpression (My+B) were compared with 112 B-lineage ALL patients without myeloid antigen coexpression (My-B) for similarity in demographic, clinical and laboratory features and their treatment outcome. My+B and My-B patients were treated with a uniform treatment protocol. Myeloid antigen coexpression was defined as more than 30% isolated leukemic cells positive for CD13 and/or CD33. The ages at diagnoses ranged from 2 months to 12 years. Median age was 4 years. The incidence of myeloid antigen coexpression was 23 per cent. Univariate analyses showed that presenting features were similar between My+B and My-B with regard to age, sex, race, FAB morphology, white cell count, hemoglobin level, platelet count, liver/spleen size, central nervous system or mediastinal involvement, presence of lymphadenopathy, and proportion of blast cells detected in the marrow. Treatment outcome were not significant between the two groups. The 2-year event free survival was achieved in 44 per cent of My+B and 57 per cent of My-B (p = 0.11). The 2-year overall survival rates were 62 per cent for My+B vs. 77 per cent for My-B (p = 0.08). This study demonstrates that myeloid antigen coexpression is fairly common and constitutes 23 per cent of childhood ALL within the Malaysian population and that it is not an adverse risk factor in childhood ALL.
  5. Nissapatorn V, Kamarulzaman A, Init I, Tan LH, Rohela M, Norliza A, et al.
    Med J Malaysia, 2002 Sep;57(3):304-10.
    PMID: 12440270 MyJurnal
    A cross-sectional study was carried out in University of Malaya Medical Centre, Kuala Lumpur. Blood samples from 100 HIV-infected patients and 203 Healthy Blood Donors (HBD) were collected and anti-Toxoplasma antibodies were detected by using conventional ELISA. The seroprevalence of toxoplasmosis in HIV/AIDS and Healthy Blood Donors were found to be 21% and 28.1% respectively. There was no significant association between the seroprevalence of toxoplasmosis and various possible risk factors i.e. contact with cat, consumption of undercooked meat and history of blood transfusion in both groups. No significant differences between Toxoplasma seroprevalence in HIV/AIDS and Healthy Blood Donors in association with presence of single or multiple risk factors were found. The mean CD4 count among HIV/AIDS patients in this study was 202.23 cell/cumm. There was no significant association between CD4 count and seropositivity for Toxoplasma antibodies in HIV/AIDS patients.
  6. Tan JA, Tan KL, Omar KZ, Chan LL, Wee YC, George E
    Eur J Pediatr, 2009 Sep;168(9):1049-54.
    PMID: 19034506 DOI: 10.1007/s00431-008-0877-9
    INTRODUCTION: Interactions of different hemoglobin variants with thalassemia alleles can result in various clinical phenotypes. HbE-beta-thalassemia generally manifests with severe anemia where individuals exhibit beta-thalassemia major with regular blood transfusions or beta-thalassemia intermedia with periodic blood transfusions. This study presents a unique Malay family with three beta-globin gene defects-HbE, Hb South Florida, and IVS1-1 (G-->A).

    MATERIALS AND METHODS: HbE activates a cryptic splice site that produces non-functional mRNAs. Hb South Florida is a rare beta-hemoglobin variant, and its interactions with other beta-thalassemia alleles have not been reported. IVS1-1 is a Mediterranean mutation that affects mRNA processing giving rise to beta(o)-thalassemia.

    RESULTS AND DISCUSSION: Fifteen mutations along the beta-globin gene complex were analyzed using the amplification refractory mutation system. Hb South Florida was identified by direct sequencing using genomic DNA.

    CONCLUSION: The affected child with HbE/IVS1-1 produced a beta-thalassemia major phenotype. Compound heterozygosity for Hb South Florida/IVS1-1 produced a beta-thalassemia carrier phenotype in the mother.

  7. Tan JA, Chin PS, Wong YC, Tan KL, Chan LL, George E
    Pathology, 2006 Oct;38(5):437-41.
    PMID: 17008283
    In Malaysia, about 4.5% of the Malay and Chinese populations are heterozygous carriers of beta-thalassaemia. The initial identification of rare beta-globin gene mutations by genomic sequencing will allow the development of simpler and cost-effective PCR-based techniques to complement the existing amplification refractory mutation system (ARMS) and gap-PCR used for the identification of beta-thalassaemia mutations.
  8. Chan LL, Mak JW, Low YT, Koh TT, Ithoi I, Mohamed SM
    Acta Trop, 2011 Jan;117(1):23-30.
    PMID: 20858455 DOI: 10.1016/j.actatropica.2010.09.004
    During a study on the quality of the indoor environment, Acanthamoeba spp. were detected in 20 out of 87 dust samples collected from air-conditioners installed in a four-story campus building located in Kuala Lumpur, Malaysia. Twenty-one cloned Acanthamoeba isolates designated as IMU1 to IMU21 were established from the positive primary cultures. Five species were identified from the 16 isolates according to the morphological criteria of Pussard and Pons; i.e. A. castellanii, A. culbertsoni, A. griffini, A. hatchetti and A. polyphaga. Species identities for the remaining five isolates (IMU4, IMU5, IMU15, IMU20 and IMU21), however, could not be determined morphologically. At genotypic characterization, these isolates were placed into T3 (IMU14); T5 (IMU16 and IMU17) and T4 (all the remaining isolates). To predict the potential pathogenicity of these Acanthamoeba isolates, thermo- and osmotolerance tests were employed; many isolates were predicted as potential human pathogens based on the outcome of these tests. This is the first time potentially pathogenic Acanthamoeba have been isolated from air-conditioners in Malaysia.
  9. Chan LL, Abdel-Latif ME, Ariffin WA, Ariffin H, Lin HP
    Br J Haematol, 2004 Sep;126(6):799-805.
    PMID: 15352983
    Treatment for childhood acute myeloid leukaemia (AML) consists of remission induction chemotherapy followed by postremission chemotherapy with or without bone marrow transplantation. The AML Berlin-Frankfurt-Munster (BFM)-83 protocol with induction-consolidation-maintenance chemotherapy for 2 years has been reported to result in a 6-year event-free survival (EFS) and event-free interval (EFI) of 49% and 61% respectively. A total of 174 Malaysian children were treated with this protocol between 1985 and 1999. The 5-year EFS and EFI was 30.7% and 48.0% respectively. The overall mortality from sepsis was 24%, which needs urgent address. The 5-year EFS for patients treated before 1993 and after 1993 was 18.6% and 41.3%, respectively (P = 0.04), while the EFI was 32% and 60.6% respectively (P = 0.034). The improvement seen after 1993 was related to a reduction in induction deaths for that period and probably reflected increased capability and familiarity to cope with the demands of the AML-BFM-83 protocol and accompanying complications in the treatment of AML.
  10. Fernando HV, Chan LL, Dang N, Santhanes D, Banneheke H, Nalliah S, et al.
    Pharm Dev Technol, 2019 Mar;24(3):348-356.
    PMID: 29799300 DOI: 10.1080/10837450.2018.1481430
    Microporous polymeric matrices prepared from poly(ɛ-caprolactone) [PCL] were evaluated for controlled vaginal delivery of the antiprotozoal agent (tinidazole) in the treatment of the sexually transmitted infection, trichomoniasis. The matrices were produced by rapidly cooling co-solutions of PCL and tinidazole in acetone to -80 °C to induce crystallisation and hardening of the polymer. Tinidazole incorporation in the matrices increased from 1.4 to 3.9% (w/w), when the drug concentration in the starting PCL solution was raised from 10 to 20% (w/w), giving rise to drug loading efficiencies up to 20%. Rapid 'burst release' of 30% of the tinidazole content was recorded over 24 h when the PCL matrices were immersed in simulated vaginal fluid. Gradual drug release occurred over the next 6 days resulting in delivery of around 50% of the tinidazole load by day 7 with the released drug retaining antiprotozoal activity at levels almost 50% that of the 'non-formulated' drug in solution form. Basic modelling predicted that the concentration of tinidazole released into vaginal fluid in vivo from a PCL matrix in the form of an intravaginal ring would exceed the minimum inhibitory concentration against Trichomonas vaginalis. These findings recommend further investigation of PCL matrices as intravaginal devices for controlled delivery of antiprotozoal agents in the treatment and prevention of sexually transmitted infections.
  11. Yu WS, Kwon SH, Agadagba SK, Chan LL, Wong KH, Lim LW
    Cells, 2021 09 21;10(9).
    PMID: 34572141 DOI: 10.3390/cells10092492
    Transcorneal electrical stimulation (TES) has emerged as a non-invasive neuromodulation approach that exerts neuroprotection via diverse mechanisms, including neurotrophic, neuroplastic, anti-inflammatory, anti-apoptotic, anti-glutamatergic, and vasodilation mechanisms. Although current studies of TES have mainly focused on its applications in ophthalmology, several lines of evidence point towards its putative use in treating depression. Apart from stimulating visual-related structures and promoting visual restoration, TES has also been shown to activate brain regions that are involved in mood alterations and can induce antidepressant-like behaviour in animals. The beneficial effects of TES in depression were further supported by its shared mechanisms with FDA-approved antidepressant treatments, including its neuroprotective properties against apoptosis and inflammation, and its ability to enhance the neurotrophic expression. This article critically reviews the current findings on the neuroprotective effects of TES and provides evidence to support our hypothesis that TES possesses antidepressant effects.
  12. Porter JB, El-Alfy M, Viprakasit V, Giraudier S, Chan LL, Lai Y, et al.
    Eur. J. Haematol., 2016 Jan;96(1):19-26.
    PMID: 25691036 DOI: 10.1111/ejh.12540
    Plasma markers in addition to serum ferritin (SF) may be useful for the assessment of iron overload; however, predictive utility may differ depending on underlying, transfusion-dependent, anemias.
  13. Tan T, Ong WS, Rajasekaran T, Nee Koo K, Chan LL, Poon D, et al.
    PLoS One, 2016;11(5):e0156008.
    PMID: 27231951 DOI: 10.1371/journal.pone.0156008
    PURPOSE: Elderly cancer patients are at increased risk for malnutrition. We aim to identify comprehensive geriatric assessment (CGA) based clinical factors associated with increased nutritional risk and develop a clinical scoring system to identify nutritional risk in elderly cancer patients.

    PATIENTS AND METHODS: CGA data was collected from 249 Asian patients aged 70 years or older. Nutritional risk was assessed based on the Nutrition Screening Initiative (NSI) checklist. Univariate and multivariate logistic regression analyses were applied to assess the association between patient clinical factors together with domains within the CGA and moderate to high nutritional risk. Goodness of fit was assessed using Hosmer-Lemeshow test. Discrimination ability was assessed based on the area under the receiver operating characteristics curve (AUC). Internal validation was performed using simulated datasets via bootstrapping.

    RESULTS: Among the 249 patients, 184 (74%) had moderate to high nutritional risk. Multivariate logistic regression analysis identified stage 3-4 disease (Odds Ratio [OR] 2.54; 95% CI, 1.14-5.69), ECOG performance status of 2-4 (OR 3.04; 95% CI, 1.57-5.88), presence of depression (OR 5.99; 95% CI, 1.99-18.02) and haemoglobin levels <12 g/dL (OR 3.00; 95% CI 1.54-5.84) as significant independent factors associated with moderate to high nutritional risk. The model achieved good calibration (Hosmer-Lemeshow test's p = 0.17) and discrimination (AUC = 0.80). It retained good calibration and discrimination (bias-corrected AUC = 0.79) under internal validation.

    CONCLUSION: Having advanced stage of cancer, poor performance status, depression and anaemia were found to be predictors of moderate to high nutritional risk. Early identification of patients with these risk factors will allow for nutritional interventions that may improve treatment tolerance, quality of life and survival outcomes.

  14. Lee LK, Lim ZF, Gu H, Chan LL, Litaker RW, Tester PA, et al.
    Sci Rep, 2020 07 09;10(1):11251.
    PMID: 32647125 DOI: 10.1038/s41598-020-68136-6
    Microhabitats influence the distribution and abundance of benthic harmful dinoflagellate (BHAB) species. Currently, much of the information on the relationships between BHABs and microhabitat preferences is based on non-quantitative anecdotal observations, many of which are contradictory. The goal of this study was to better quantify BHAB and microhabitat relationships using a statistically rigorous approach. Between April 2016 to May 2017, a total of 243 artificial substrate samplers were deployed at five locations in the Perhentian Islands, Malaysia while simultaneous photo-quadrat surveys were performed to characterize the benthic substrates present at each sampling site. The screen samplers were retrieved 24 h later and the abundances of five BHAB genera, Gambierdiscus, Ostreopsis, Coolia, Amphidinium, and Prorocentrum were determined. Substrate data were then analyzed using a Bray-Curtis dissimilarity matrix to statistically identify distinct microhabitat types. Although BHABs were associated with a variety of biotic and abiotic substrates, the results of this study demonstrated differing degrees of microhabitat preference. Analysis of the survey results using canonical correspondence analysis explained 70.5% (horizontal first axis) and 21.6% (vertical second axis) of the constrained variation in the distribution of various genera among microhabitat types. Prorocentrum and Coolia appear to have the greatest range being broadly distributed among a wide variety of microhabitats. Amphidinium was always found in low abundances and was widely distributed among microhabitats dominated by hard coral, turf algae, sand and silt, and fleshy algae and reached the highest abundances there. Gambierdiscus and Ostreopsis had more restricted distributions. Gambierdiscus were found preferentially associated with turf algae, hard coral and, to a lesser extent, fleshy macroalgae microhabitats. Ostreopsis, almost always more abundant than Gambierdiscus, preferred the same microhabitats as Gambierdiscus and were found in microbial mats as well. With similar habitat preferences Ostreopsis may serve as an indicator organism for the presence of Gambierdiscus. This study provides insight into how BHAB-specific microhabitat preferences can affect toxicity risks.
  15. Yong YK, Wen NCM, Yeo GEC, Chew ZX, Chan LL, Md Zain NZ, et al.
    PMID: 34574752 DOI: 10.3390/ijerph18189828
    Several bacterial species cause post-operative infections, which has been a critical health concern among hospital patients. Our study in this direction is a much-needed exploratory study that was carried out at the National Heart Institute (IJN) of Malaysia to examine the virulence properties of causative bacteria obtained from postoperative patients. The bacterial isolates and data were provided by the IJN. Antibiotic resistance gene patterns, and the ability to form biofilm were investigated for 127 isolates. Klebsiella pneumoniae (36.2%) was the most common isolate collected, which was followed by Pseudomonas aeruginosa (26%), Staphylococcus aureus (23.6%), Streptococcus spp. (8.7%) and Acinetobacter baumannii (5.5%). There were 49 isolates that showed the presence of multidrug resistance genes. The mecA gene was surprisingly found in methicillin-susceptible S. aureus (MSSA), which also carried the ermA gene from those erythromycin-susceptible strains. The phenotypic antibiotic resistance profiles varied greatly between isolates. Findings from the biofilm assay revealed that 44 of the 127 isolates demonstrated the ability to produce biofilms. Our findings provide insights into the possibility of some of these bacteria surviving under antibiotic stress, and some antibiotic resistance genes being silenced.
  16. Chan LL, Toh HC, Jaikwang K, Loo EM, Wong JH, Liew YK, et al.
    Acta Trop, 2022 Feb 16.
    PMID: 35182491 DOI: 10.1016/j.actatropica.2022.106372
    Pathogenic Acanthamoeba species are the causative agents of Acanthamoeba keratitis and granulomatous amoebic encephalitis. Members of this amoeba genus are ubiquitous in the environments. In Malaysia, most environmental studies performed to date have targeted the detection and characterisation of Acanthamoeba sp. in different water sources, dust and soil samples collected near human habitats. However, no local study has yet to examine these amoebae in a forest, an isolated terrestrial environment, where human activity is relatively scarce. Further, there are also limited studies to investigate the same globally. The current study reported the isolation, morphological and genotypic characterisations of eleven Acanthamoeba sp. isolated from soils of the Payeh Maga Highland forest, Sarawak, Malaysia. Morphological analysis revealed that nine isolates belonged to Group II, whereas two isolates belonged to Group III as defined by the criteria of Pussard and Pons. The phylogenetic analysis based on complete 18S rRNA gene sequences showed that the isolates belonged to the rare T1 (six isolates), T6 (two isolates) and T13 (three isolates) genotypes. To the best of our knowledge, this is the first report about the detection of T6 Acanthamoeba sp. in this country. Overall, the current findings have enriched the knowledge pertaining to the occurrence, morphological and genotypic characteristics of Acanthamoeba sp. in an isolated terrestrial environment of Malaysia.
  17. Zhu J, Lee WH, Yip KC, Wu Z, Wu J, Leaw CP, et al.
    Sci Total Environ, 2023 May 10;872:162236.
    PMID: 36791857 DOI: 10.1016/j.scitotenv.2023.162236
    The dinoflagellates Gambierdiscus and Fukuyoa can produce Ciguatoxins (CTXs) and Maitotoxins (MTXs) that lead to ciguatera poisoning (CP). The CP hotspots, however, do not directly relate to the occurrence of the ciguatoxic Gambierdiscus and Fukuyoa. Species-wide investigations often showed no association between CTX level and the molecular identity of the dinoflagellates. In the Pacific region, Kiribati is known as a CP hotspot, while Malaysia has only three CP outbreaks reported thus far. Although ciguatoxic strains of Gambierdiscus were isolated from both Kiribati and Malaysia, no solid evidence on the contribution of ciguatoxic strains to the incidence of CP outbreak was recorded. The present study aims to investigate the regional differences in CP risks through region-specific toxicological assessment of Gambierdiscus and Fukuyoa. A total of 19 strains of Gambierdiscus and a strain of Fukuyoa were analyzed by cytotoxicity assay of the neuro-2a cell line, hemolytic assay of fish erythrocytes, and high-resolution mass spectrometry. Gambierdiscus from both Kiribati and Malaysia showed detectable ciguatoxicity; however, the Kiribati strains were more hemolytic. Putative 44-methylgambierone was identified as part of the contributors to the hemolytic activity, and other unknown hydrophilic toxins produced can be potentially linked to higher CP incidence in Kiribati.
  18. Chan LL, Ho YY, Taylor ME, Mcveigh C, Jung S, Armstrong E, et al.
    Arch Gerontol Geriatr, 2024 Mar 21;123:105422.
    PMID: 38579379 DOI: 10.1016/j.archger.2024.105422
    PURPOSE: This systematic review aimed to update fragility hip fracture incidences in the Asia Pacific, and compare rates between countries/regions.

    METHOD: A systematic search was conducted in four electronic databases. Studies reporting data between 2010 and 2023 on the geographical incidences of hip fractures in individuals aged ≥50 were included. Exclusion criteria were studies reporting solely on high-trauma, atypical, or periprosthetic fractures. We calculated the crude incidence, age- and sex-standardised incidence, and the female-to-male ratio. The systematic review was registered with PROSPERO (CRD42020162518).

    RESULTS: Thirty-eight studies were included across nine countries/regions (out of 41 countries/regions). The crude hip fracture incidence ranged from 89 to 341 per 100,000 people aged ≥50, with the highest observed in Australia, Taiwan, and Japan. Age- and sex-standardised rates ranged between 90 and 318 per 100,000 population and were highest in Korea and Japan. Temporal decreases in standardised rates were observed in Korea, China, and Japan. The female-to-male ratio was highest in Japan and lowest in China.

    CONCLUSION: Fragility hip fracture incidence varied substantially within the Asia-Pacific region. This observation may reflect actual incidence differences or stem from varying research methods and healthcare recording systems. Future research should use consistent measurement approaches to enhance international comparisons and service planning.

  19. Ariffin H, Ab Rahman S, Jawin V, Foo JC, Amram NF, Mahmood NM, et al.
    J Paediatr Child Health, 2020 Mar;56(3):379-383.
    PMID: 31479560 DOI: 10.1111/jpc.14621
    AIM: Inborn errors of immunity (IEI) comprise a heterogeneous group of disorders of the immune system, most of which are curable by haematopoietic stem cell transplantation (HSCT). We present a 25-year audit of HSCT for IEI at a tertiary-level academic hospital in Malaysia.

    METHODS: Review of medical records of all cases of IEI who underwent HSCT between January 1993 and December 2018 at our centre. Diagnoses, complications, HSCT protocols and outcome data were studied.

    RESULTS: There were 20 patients (19 boys) with a median age at diagnosis of 11 months (range: 2 months to 12 years). Eleven of 19 (58%) had malnutrition at presentation. Donor sources were variable: 13 (65%) matched sibling donor (MSD), 4 (20%) human leukocyte antigen-haploidentical donor (HD) and 3 (15%) matched unrelated donor (MUD). Conditioning regimens were physician-dependent and adapted to each patient's clinical status. Grades III-IV acute graft-versus-host disease occurred in two of three cases who received MUD grafts, 50% in those who received HD, and 8% in the MSD group. Transplant-related mortality at day +100 was 5%. With a median follow-up of 7.5 years, 18 (90%) patients are alive and free of infections.

    CONCLUSION: Outcome of HSCT for IEI in our centre is comparable with international reports. HSCT results using HD and MUD grafts are also good despite challenges from acute graft-versus-host disease, providing a feasible alternative for patients without matched donors.

  20. Lim ZF, Luo Z, Lee LK, Hii KS, Teng ST, Chan LL, et al.
    Harmful Algae, 2019 Mar;83:95-108.
    PMID: 31097256 DOI: 10.1016/j.hal.2019.01.007
    Thirteen isolates of Prorocentrum species were established from the coral reefs of Perhentian Islands Marine Park, Malaysia and underwent morphological observations and molecular characterization. Six species were found: P. caipirignum, P. concavum, P. cf. emarginatum, P. lima, P. mexicanum and a new morphotype, herein designated as P. malayense sp. nov. Prorocentrum malayense, a species closely related to P. leve, P. cf. foraminosum, P. sp. aff. foraminossum, and P. concavum (Clade A sensu Chomérat et al. 2018), is distinguished from its congeners as having larger thecal pore size and a more deeply excavated V-shaped periflagellar area. Platelet arrangement in the periflagellar area of P. malayense is unique, with the presence of platelet 1a and 1b, platelet 2 being the most anterior platelet, and a broad calabash-shaped platelet 3. The species exhibits consistent genetic sequence divergences for the nuclear-encoded large subunit ribosomal RNA gene (LSU rDNA) and the second internal transcribed spacer (ITS2). The phylogenetic inferences further confirmed that it represents an independent lineage, closely related to species in Clade A sensu Chomérat et al. Pairwise comparison of ITS2 transcripts with its closest relatives revealed the presence of compensatory base changes (CBCs). Toxicity analysis showed detectable levels of okadaic acid in P. lima (1.0-1.6 pg cell-1) and P. caipirignum (3.1 pg cell-1); this is the first report of toxigenic P. caipirignum in the Southeast Asian region. Other Prorocentrum species tested, including the new species, however, were below the detection limit.
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