Development of molecular diagnostics and antiviral therapy against enterovirus 71 (EV71)

Ph.DDOCTOR OF PHILOSOPH

Urban Malaysian Adolescents' Online Activities.

Many Malaysian adolescents are immersed in the global contemporary,technological and digital culture. Their everyday literacy practices involve participation in a range of activities on the Internet

Metastasis from Gastric Carcinoma Causing Ureteral Obstruction

Gastric carcinoma rarely metastasizes to the lower urinary tract. Adenocarcinomas are commonly found in the stomach, however this histologic entity is rarely seen in the bladder and often difficult to distinguish primary from secondary with only histopathologic changes. We report a 61 year old man with a history of total gastrectomy for gastric adenocarcinoma presenting six months later with metastasis to the lower urinary tract. He presented with nonspecific symptoms and laboratory investigations showed progressive elevation of serum creatinine level. Despite implantation of double J stents, renal function did not improve. Computed tomography revealed enlarged mesenteric lymph node, bilateral hydronephrosis and hydroureter likely due to bladder wall thickening at the vesicoureteric junction. Retrograde pyelogram and biopsies taken from the bladder revealed secondary bladder adenocarcinoma. In summary, metastatic carcinoma of the lower urinary tract should be considered in patients with history of gastric adenocarcinoma whose presentation is consistent with ureteral obstruction

Controlled-release nanoencapsulating microcapsules to combat inflammatory diseases

The World Health Organization (WHO) has reported that globally 235 million people suffer from chronic and other inflammatory diseases. The short half-lives of nonsteroidal anti-inflammatory drugs (NSAIDs) and their notoriety in causing gastrointestinal discomforts, warrants these drugs to be released in a controlled and sustained manner. Although polymeric particles have been widely used for drug delivery, there are few reports that showcase their ability in encapsulating and sustaining the release of NSAIDs. In this paper, polymeric nanoencapsulating microcapsules loaded with NSAIDs were fabricated using solid/water/oil/water emulsion solvent evaporation method. Two NSAIDs, ibuprofen and naproxen, were first pre-loaded into nanoparticles and then encapsulated into a larger hollow microcapsule that contained the third NSAID, celecoxib. A high encapsulation efficiency (%) of these NSAIDs was achieved and a sustained release (up to 30 days) of these drugs in phosphate-buffered saline was observed. Then, a gastrointestinal drug – cimetidine (CIM) – was co-loaded with the NSAIDs. This floating delivery system exhibited excellent buoyancy (~88% up to 24 h) in simulated gastric fluid. It also allowed a sequential release of the drugs, whereby an immediate release of CIM followed by NSAIDs was observed. Drug release of the NSAIDs observed Fickian diffusion mechanism, whereas CIM observed non-Fickian diffusion. Therefore, this delivery system is a promising platform to control the delivery of NSAIDs to combat inflammatory diseases, thereby protecting against possible gastrointestinal side effects that may arise from the overuse of NSAIDs.MOE (Min. of Education, S’pore)Published versio

Orchids of cloud forest in Genting Highlands, Pahang, Malaysia

An inventory of orchid species diversity was carried out in cloud forest of Genting Highlands, which is one of the most developed highland areas in Peninsular Malaysia. Since 1967, construction of roads and hotel complexes has had a serious impact on its physical environment and vegetation. Habitat destructions together with climate change might have caused some orchid species to be extirpated locally or extinct. The cloud forest of Genting Highlands consists of four major peaks, Gunung Ulu Kali, Gunung Chin Chin, Gunung Lari Tembakau and Gunung Mengkuang. However, not much study on orchid diversity was conducted in these areas, therefore, this study is timely and essential to evaluate the current orchid diversity after a gap of three decades. Combined findings from the current study, previous published works and specimens deposited in local herbaria, including those at the Universiti Malaya, Universiti Kebangsaan Malaysia, Forest Researh Institute of Malaysia and Biology Department, Faculty of Science, Universiti Putra Malaysia and Singapore Botanic Gardens, an updated list of orchid species found in the cloud forests of Genting Highlands is presented. A total of 134 orchid taxa were recorded, comprised of 51 genera, 132 species, 1 subspecies and 2 varieties, of which 46 are new records to Genting Highlands. Hymenorchis javanica, a species previously reported as endemic to West Jawa was recently discovered in Gunung Ulu Kali. Thirty-three species discovered during this study are currently classified as endemic to Peninsular Malaysia, of which 20 are endemic to Pahang, Perak and Selangor and a very narrowly endemic species; Corybas villosus to Gunung Ulu Kali. Through our observations, most of the orchid species in Gunung Ulu Kali are very susceptible to disappearance due to loss of habitat and local climate change. An assessment of conservation status according to IUCN criterion revealed that 47 orchid taxa from Gunung Ulu Kali were threatened with extinction. Conservation actions were suggested to conserve the orchid diversity in the cloud forest areas of Genting Highlands

Production, safety, health effects and applications of diacylglycerol functional oil in food systems: a review

Diacylglycerol (DAG) is a world leading anti-obesity functional cooking oil synthesized via structural modification of conventional fats and oils. DAG exits in three stereoisomers namely sn-1,2-DAG, sn-1,3-DAG, and sn-2,3-DAG. DAG particularly sn-1,3-DAG demonstrated to have the potential in suppressing body fat accumulation and lowering postprandial serum triacylglycerol, cholesterol and glucose level. DAG also showed to improve bone health. This is attributed to DAG structure itself that caused it to absorb and digest via different metabolic pathway than conventional fats and oils. With its purported health benefits, many studies attempt to enzymatically or chemically synthesis DAG through various routes. DAG has also received wide attention as low calorie fat substitute and has been incorporated into various food matrixes. Despite being claimed as healthy cooking oil the safety of DAG still remained uncertain. DAG was banned from sale as it was found to contain probable carcinogen glycidol fatty acid esters. The article aims to provide a comprehensive and latest review of DAG emphasizing on its structure and properties, safety and regulation, process developments, metabolism and beneficial health attributes as well as its applications in the food industry

Prevention of high body mass index and eating disorders : a systematic review and meta-analysis

Background: Eating disorders (EDs) and high body mass index (BMI) are two important public health issues with significant health and cost impacts. The aim of this systematic review and meta-analysis was to establish whether interventions are effective in preventing both issues. Methods: Electronic databases were searched up to 10 May 2021. Studies were included if they were randomised or quasi-randomised controlled trials that evaluated a preventive intervention (regardless of its aim to prevent ED, high BMI or both) and reported both EDs and BMI-related outcomes. Both narrative synthesis and meta-analysis were used to synthesise the results. Publication bias was also investigated. Results: Fifty-four studies were included for analysis. The primary aim of the studies was ED prevention (n = 23), high BMI prevention (n = 21) and both ED and high BMI prevention (n = 10). Meta-analysis results indicated that preventive interventions had a significant effect on several ED outcomes including dieting, shape and weight concerns, body dissatisfaction, negative affect, eating disorder symptoms and internalization, with effect sizes ranging from – 0.16 (95% CI – 0.27, – 0.06) to – 0.61 (95% CI – 0.29, – 0.04). Despite several studies that demonstrated positive impacts on BMI, there was no significant effect on BMI-related measures in the meta-analysis. The risk of publication bias was low for the majority of the pooled effect results. Conclusion: Preventive interventions were effective for either high BMI or EDs. However, there is limited evidence to show that current preventive interventions were effective in reducing both outcomes. Further research is necessary to explore the risk factors that are shared by these weight-related disorders as well as effective prevention interventions. Level of evidence: Level I: systematic review

Review on the current state of diacylglycerol production using enzymatic approach

Enzymatic production of diacylglycerol (DAG)-enriched oil has been investigated extensively due to its health benefits with total annual sales of approximately USD 200 million in Japan since its introduction in the late 1990s till 2009. Enzymatic catalysis had been proven to exhibit improved results with respect to yield, purity, reaction time, and stability in comparison with chemical catalysis. The cost of the enzymes, however, is the main hurdle to the widespread use of enzyme for commercial DAG production. This paper attempts to review and summarize various lipase-mediated technological methods for DAG production. Critical aspects such as process considerations on DAG synthesis, mass transfer limitations as well as kinetic mechanism models developed for each enzymatic approach in DAG synthesis are also presented and discussed. In addition, possible reactor configurations were evaluated, if lipase-assisted DAG production is to be technically and economically feasible at an industrial scale

The integration of InGaP LEDs with CMOS on 200 mm silicon wafers

The integration of photonics and electronics on a converged silicon CMOS platform is a long pursuit goal for both academe and industry. We have been developing technologies that can integrate III-V compound semiconductors and CMOS circuits on 200 mm silicon wafers. As an example we present our work on the integration of InGaP light-emitting diodes (LEDs) with CMOS. The InGaP LEDs were epitaxially grown on high-quality GaAs and Ge buffers on 200 mm (100) silicon wafers in a MOCVD reactor. Strain engineering was applied to control the wafer bow that is induced by the mismatch of coefficients of thermal expansion between III-V films and silicon substrate. Wafer bonding was used to transfer the foundry-made silicon CMOS wafers to the InGaP LED wafers. Process trenches were opened on the CMOS layer to expose the underneath III-V device layers for LED processing. We show the issues encountered in the 200 mm processing and the methods we have been developing to overcome the problems

Negative chromatography of hepatitis B virus-like particles: comparative study of different adsorbent designs

Purification of virus-like particles (VLPs) in bind-and-elute mode has reached a bottleneck. Negative chromatography has emerged as the alternative solution; however, benchmark of negative chromatography media and their respective optimized conditions are absent. Hence, this study was carried out to compare the performance of different negative chromatography media for the purification of hepatitis B VLPs (HB-VLPs) from clarified Escherichia coli feedstock. The modified anion exchange media, core-shell adsorbents (InertShell and InertLayer 1000) and polymer grafted adsorbents (SQ) were compared. The results of chromatography from packed bed column of core-shell adsorbents showed that there is a trade-off between the purity and recovery of HB-VLPs in the flowthrough fraction due to the shell thickness. Atomic force microscopic analysis revealed funnel-shaped pore channels in the shell layer which may contribute to the entrapment of HB-VLPs. A longer residence time at a lower feed flow rate (0.5ml/min) improved slightly the HB-VLPs purity in all modified adsorbents, but the recovery in InertShell reduced substantially. The preheat-treatment is not recommended for the negative chromatography as the thermal-induced co-aggregation of HCPs and HB-VLPs would flow along with HB-VLPs and thus reduced the HB-VLPs purity in the flowthrough. Further reduction in the feedstock concentration enhanced the purity of HB-VLPs especially in InertLayer 1000 but reduced substantially the recovery of HB-VLPs. In general, the polymer grafted adsorbent, SQ, performed better than the core-shell adsorbents in handling a higher feedstock concentration