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Toxic bloom of Pseudo-nitzschia cuspidata (Bacillariophyceae) and domoic acid contamination of bivalve molluscs in Malaysia Borneo

Teng ST, Abdullah N, Hanifah AH, Tan SN, Gao C, Law IK, et al.

Toxicon, 2021 Sep 30;202:132-141.
PMID: 34600910 DOI: 10.1016/j.toxicon.2021.09.018

In March 2018, an algal bloom of Pseudo-nitzschia was detected, for the first time, in a semi-enclosed lagoon in Miri, Sarawak, Malaysia Borneo. The plankton samples were collected for cell enumeration and species identification by electron microscopy and molecular characterization. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was performed to detect and quantify the neurotoxin domoic acid (DA) in both the plankton and shellfish samples. The abundance of Pseudo-nitzschia cells ranged from 5.6 × 105 to 3.5 × 106 cell L-1 during the bloom event. Morphological observation of the cells by transmission electron microscopy showed that the plankton samples comprised a single Pseudo-nitzschia morphotype resembling P. cuspidata. The ITS2 sequence-structure phylogenetic inference further supported the species identity as Pseudo-nitzschia cuspidata. Low levels of DA were detected in the plankton samples, with cellular DA, particulate DA, and dissolved DA of 257-504 fg DA cell-1, 676 ng L-1, and 15 ng L-1, respectively. The amount of DA, 8 μg g-1 tissue, was found present in the shellfish sample (Magallana sp.) which is below the regulatory limit of 20 μg DA g-1 tissue. The study documented, for the first time, DA contamination in shellfish that associated with bloom of P. cuspidata in the Western Pacific region.
Corrigendum to "Toxic bloom of Pseudo-nitzschia cuspidata (Bacillariophyceae) and domoic acid contamination of bivalve molluscs in Malaysia Borneo" [Toxicon 202 (2021) 132-141]

Teng ST, Abdullah N, Hanifah AH, Tan SN, Gao C, Law IK, et al.

Toxicon, 2022 Jan 15;205:99.
PMID: 34872755 DOI: 10.1016/j.toxicon.2021.12.002
Fulltext Effect of Edible Bird's Nest Extract on Lipopolysaccharide-Induced Impairment of Learning and Memory in Wistar Rats

Careena S, Sani D, Tan SN, Lim CW, Hassan S, Norhafizah M, et al.

Evid Based Complement Alternat Med, 2018;2018:9318789.
PMID: 30186358 DOI: 10.1155/2018/9318789

Cognitive disability is a common feature associated with a variety of neurological conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), brain injury, and stroke. Emerging evidence has demonstrated that neuroinflammation plays an important role in the development of cognitive impairment. Current available therapies are relatively ineffective in treating or preventing cognitive disabilities, thus representing an important, unfulfilled medical need. Hence, developing potential treatment is one of the major areas of research interest. Edible bird's nests (EBN) are nests formed by swiftlet's saliva containing sialic acid, which is believed to improve brain function. This present study was embarked upon to evaluate the learning and memory enhancing potential effect of EBN by using Morris water maze test in a Wistar rat model of LPS-induced neuroinflammation. LPS elicited cognitive impairment in the rats by significantly increasing the escape latency while decreasing the number of entries in the probe trial, which are coupled with increased production of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and oxidative markers (ROS and TBARS) in the hippocampus. Treatment with EBN (125 mg/kg, 250 mg/kg, and 500 mg/kg; p.o.) effectively reversed the effect of LPS on escape latency and probe trial and, in addition, inhibited the LPS-induced upregulation of proinflammatory cytokines and oxidative markers. These findings are suggestive that there is existence of neuroprotective effect contained inside the edible bird's nest.
Blooms of diatom and dinoflagellate associated with nutrient imbalance driven by cycling of nitrogen and phosphorus in anaerobic sediments in Johor Strait (Malaysia)

Chai X, Li X, Hii KS, Zhang Q, Deng Q, Wan L, et al.

Mar Environ Res, 2021 Jul;169:105398.
PMID: 34171592 DOI: 10.1016/j.marenvres.2021.105398

Coastal eutrophication is one of the pivotal factors driving occurrence of harmful algal blooms (HABs), whose underlying mechanism remained unclear. To better understand the nutrient regime triggering HABs and their formation process, the phytoplankton composition and its response to varying nitrogen (N) and phosphorus (P), physio-chemical parameters in water and sediment in Johor Strait in March 2019 were analyzed. Surface and sub-surface HABs were observed with the main causative species of Skeletonema, Chaetoceros and Karlodinium. The ecophysiological responses of Skeletonema to the low ambient N/P ratio such as secreting alkaline phosphatase, regulating cell morphology (volume; surface area/volume ratio) might play an important role in dominating the community. Anaerobic sediment iron-bound P release and simultaneous N removal by denitrification and anammox, shaped the stoichiometry of N and P in water column. The decrease of N/P ratio might shift the phytoplankton community into the dominance of HABs causative diatoms and dinoflagellates.
Diverse harmful microalgal community assemblages in the Johor Strait and the environmental effects on its community dynamics

Hii KS, Mohd-Din M, Luo Z, Tan SN, Lim ZF, Lee LK, et al.

Harmful Algae, 2021 07;107:102077.
PMID: 34456026 DOI: 10.1016/j.hal.2021.102077

Coastal ecosystems are often subjected to anthropogenic disturbances that lead to water quality deterioration and an increase in harmful algal bloom (HAB) events. Using the next-generation molecular tool of 18S rDNA metabarcoding, we examined the community assemblages of HAB species in the Johor Strait, Malaysia between May 2018 and September 2019, covering 19 stations across the strait. The molecular operational taxonomic units (OTUs) of HAB taxa retrieved from the dataset (n = 194) revealed a much higher number of HAB taxa (26 OTUs) than before, with 12 taxa belong to new records in the strait. As revealed in the findings of this study, the diversity and community structure of HAB taxa varied significantly over time and space. The most common and abundant HAB taxa in the strait (frequency of occurrence >70%) comprised Heterosigma akashiwo, Fibrocapsa japonica, Pseudo-nitzschia pungens, Dinophysis spp., Gymnodinium catenatum, Alexandrium leei, and A. tamiyavanichii. Also, our results demonstrated that the HAB community assemblages in the strait were dependent on the interplay of environmental variables that influence by the monsoonal effects. Different HAB taxa, constitute various functional types, occupied and prevailed in different environmental niches across space and time, leading to diverse community assemblages and population density. This study adds to the current understandings of HAB dynamics and provides a robust overview of temporal-spatial changes in HAB community assemblages along the environmental gradients in a tropical eutrophic coastal ecosystem.
Phylogeny and species delineation in the marine diatom Pseudo-nitzschia (Bacillariophyta) using cox1, LSU, and ITS2 rRNA genes: A perspective in character evolution

Lim HC, Tan SN, Teng ST, Lundholm N, Orive E, David H, et al.

J Phycol, 2018 04;54(2):234-248.
PMID: 29377161 DOI: 10.1111/jpy.12620

Analyses of the mitochondrial cox1, the nuclear-encoded large subunit (LSU), and the internal transcribed spacer 2 (ITS2) RNA coding region of Pseudo-nitzschia revealed that the P. pseudodelicatissima complex can be phylogenetically grouped into three distinct clades (Groups I-III), while the P. delicatissima complex forms another distinct clade (Group IV) in both the LSU and ITS2 phylogenetic trees. It was elucidated that comprehensive taxon sampling (sampling of sequences), selection of appropriate target genes and outgroup, and alignment strategies influenced the phylogenetic accuracy. Based on the genetic divergence, ITS2 resulted in the most resolved trees, followed by cox1 and LSU. The morphological characters available for Pseudo-nitzschia, although limited in number, were overall in agreement with the phylogenies when mapped onto the ITS2 tree. Information on the presence/absence of a central nodule, number of rows of poroids in each stria, and of sectors dividing the poroids mapped onto the ITS2 tree revealed the evolution of the recently diverged species. The morphologically based species complexes showed evolutionary relevance in agreement with molecular phylogeny inferred from ITS2 sequence-structure data. The data set of the hypervariable region of ITS2 improved the phylogenetic inference compared to the cox1 and LSU data sets. The taxonomic status of P. cuspidata and P. pseudodelicatissima requires further elucidation.
Prolonged high biomass diatom blooms induced formation of hypoxic-anoxic zones in the inner part of Johor Strait

Mohd-Din M, Abdul-Wahab MF, Mohamad SE, Jamaluddin H, Shahir S, Ibrahim Z, et al.

Environ Sci Pollut Res Int, 2020 Dec;27(34):42948-42959.
PMID: 32725555 DOI: 10.1007/s11356-020-10184-6

The Johor Strait has experienced rapid development of various human activities and served as the main marine aquaculture area for the two countries that bordered the strait. Several fish kill incidents in 2014 and 2015 have been confirmed, attributed to the algal blooms of ichthyotoxic dinoflagellates; however, the cause of fish kill events after 2016 was not clarified and the causative organisms remained unknown. To clarify the potential cause of fish kills along the Johor Strait, a 1-year field investigation was conducted with monthly sampling between May 2018 and April 2019. Monthly vertical profiles of physical water parameters (temperature, salinity, and dissolved oxygen levels) were measured in situ at different depths (subsurface, 1 m, 5 m, and 8 m) depending on the ambient depth of the water column at the sampling stations. The spatial-temporal variability of macronutrients and chlorophyll a content was analyzed. Our results showed that high chlorophyll a concentration (up to 48.8 μg/L) and high biomass blooms of Skeletonema, Chaetoceros, Rhizosolenia, and Thalassiosira were observed seasonally at the inner part of the strait. A hypoxic to anoxic dead zone, with the dissolved oxygen levels ranging from 0.19 to 1.7 mg/L, was identified in the inner Johor Strait, covering an estimated area of 10.3 km2. The occurrence of high biomass diatom blooms and formation of the hypoxic-anoxic zone along the inner part Johor Strait were likely the culprits of some fish kill incidents after 2016.
Donor Diabetes and Steatosis Affects Recipient Survival Following Liver Transplantation Based on Etiology of Liver Cirrhosis

Lim WH, Ng CH, Tan DJH, Xiao J, Fu CE, Ong C, et al.

Transplantation, 2024 Feb 01;108(2):473-482.
PMID: 37439778 DOI: 10.1097/TP.0000000000004718

BACKGROUND: Liver transplantation (LT) offers patients with decompensated cirrhosis the best chance at long-term survival. With the rising prevalence of diabetes, further clarity is needed on the impact of receiving a liver allograft from a donor with diabetes on post-LT outcomes. This study aims to evaluate the impact of donor diabetes on clinical outcomes after LT.
METHODS: This is a retrospective analysis of the United Network for Organ Sharing registry data of LT recipients from January 1, 2000, to December 31, 2021. Outcomes analysis was performed using Cox proportional model for all-cause mortality and graft failure. Confounding was reduced by coarsened exact matching causal inference analysis.
RESULTS: Of 66 960 donors identified, 7178 (10.7%) had diabetes. Trend analysis revealed a longitudinal increase in the prevalence of donor diabetes ( P
Fulltext Does dose reduction of afatinib affect treatment outcomes of patients with EGFR-mutant metastatic non-small cell lung cancer in real-world clinical practice?

Poh ME, Chai CS, Liam CK, Ho GF, Pang YK, Hasbullah HH, et al.

Transl Lung Cancer Res, 2024 Feb 29;13(2):307-320.
PMID: 38496703 DOI: 10.21037/tlcr-23-691

BACKGROUND: Afatinib can be started at a dose lower than the recommended starting dose of 40 mg/day for the treatment of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC), however treatment outcomes in real-world clinical practice remains unclear.
METHODS: This retrospective study of patients with NSCLC from 18 major hospitals (public, private or university teaching hospitals) enrolled in Malaysia's National Cardiovascular and Thoracic Surgical Database (NCTSD) assessed the efficacy of lower doses of afatinib on treatment outcomes in a real-world clinical practice. Data on clinical characteristics, afatinib dosing, and treatment outcomes for patients included in NCTSD from 1st January 2015 to 31st December 2020 were analyzed.
RESULTS: Of the 133 patients studied, 94.7% had adenocarcinoma. Majority of the patients (60.9%) had EGFR exon 19 deletion and 23.3% had EGFR exon 21 L858R point mutation. The mean age of patients was 64.1 years and majority (83.5%) had Eastern Cooperative Oncology Group performance status of 2-4 at diagnosis. The most common afatinib starting doses were 40 mg (37.6%), 30 mg (29.3%), and 20 mg (26.3%) once daily (OD), respectively. A quarter of patients had dose reduction (23.3%) due to side effects or cost constraints. Majority of the patients had partial response to afatinib (63.2%) whilst 2.3% had complete response. Interestingly, the objective response rate was significantly higher (72.3%) with afatinib OD doses of less than 40 mg compared to 40 mg (54.0%) (P=0.032). Patients on lower doses of afatinib were two times more likely to achieve an objective response [odds ratio =2.64; 95% confidence interval (CI): 1.20-5.83; P=0.016]. These patients had a numerically but not statistically longer median time to treatment failure (TTF). Median TTF (95% CI) for the overall cohort was 12.4 (10.02-14.78) months. Median overall survival (95% CI) was 21.30 (15.86-26.75) months.
CONCLUSIONS: Lower afatinib doses (<40 mg OD) could be equally effective as standard dose in patients with EGFR-mutant advanced NSCLC and may be more suited to Asian patients, minimizing side effects that may occur at higher dosages of afatinib leading to dose interruptions and affecting treatment outcomes.