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Search Results: 1 - 10 of 126044 matches for " Swee T. Tan "
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Biology of Infantile Haemangioma
Tinte Itinteang,Paul F. Davis,Swee T. Tan
Frontiers in Surgery , 2014, DOI: 10.3389/fsurg.2014.00038
Abstract: Infantile haemangioma (IH), the most common tumour of infancy, is characterised by an initial proliferation during infancy followed by spontaneous involution over the next 5-10 years, often leaving a fibro-fatty residuum. IH is traditionally considered a tumour of the microvasculature. However, recent data shows the critical role of stem cells in the biology of IH with emerging evidence suggesting an embryonic developmental anomaly due to aberrant proliferation and differentiation of a haemogenic endothelium with a neural crest phenotype that possesses the capacity for endothelial, haematopoietic, mesenchymal and neuronal differentiation. Current evidence suggests a putative placental chorionic mesenchymal core cell embolic origin of IH during the first trimester. This review outlines the emerging role of stem cells and their interplay with the cytokine niche that promotes a post-natal environment conducive for vasculogenesis involving VEGFR-2 and its ligand VEGF-A and the IGF-2 ligand in promoting cellular proliferation, and the TRAIL-OPG anti-apoptotic pathway in preventing cellular apoptosis in IH. The discovery of the role of the renin-angiotensin system in the biology of IH provides a plausible explanation for the programmed biologic behaviour and the β-blocker induced accelerated involution of this enigmatic condition. This crucially involves the vasoactive peptide, angiotensin II, that promotes cellular proliferation in IH predominantly via its action on the ATIIR2 isoform. The role of the RAS in the biology of IH is further supported by the effect of captopril, an ACE inhibitor, in inducing accelerated involution of IH. The discovery of the critical role of RAS in IH represents a novel and fascinating paradigm shift in the understanding of human development, IH and other tumours in general.
Mast cells dysregulate apoptotic and cell cycle genes in mucosal squamous cell carcinoma
Sydney Ch'ng, Michael Sullivan, Lan Yuan, Paul Davis, Swee T Tan
Cancer Cell International , 2006, DOI: 10.1186/1475-2867-6-28
Abstract: This study explores the effects of mast cells on the proliferation and gene expression profile of mucosal squamous cell carcinoma using human mast cell line (HMC-1) and human glossal squamous cell carcinoma cell line (SCC25).HMC-1 and SCC25 were co-cultured in a two-compartment chamber, separated by a polycarbonate membrane. HMC-1 was stimulated to degranulate with calcium ionophore A23187. The experiments were done in quadruplicate. Negative controls were established where SCC25 were cultured alone without HMC-1. At 12, 24, 48 and 72 hours, proliferation and viability of SCC25 were assessed with MTT colorimetric assay. cDNA microarray was employed to study differential gene expression between co-cultured and control SCC25.HMC-1/SCC25 co-culture resulted in suppression of growth rate for SCC-25 (34% compared with 110% for the control by 72 hours, p < 0.001), and dysregulation of genes TRAIL, BIRC4, CDK6, Cyclin G2 and CDC6 in SCC25.We show that mast cells have a direct inhibitory effect on the proliferation of mucosal squamous cell carcinoma in vitro by dysregulating key genes in apoptosis and cell cycle control.Mucosal squamous cell carcinoma of the head and neck (HNSCC) is the sixth most common cancer afflicting men in the developed world. Despite diagnostic and therapeutic advances, there has been little improvement in the mortality over the last three decades [1]. Although the genetic events underlying HNSCC progression are slowly unravelling [2], very little is known about the interactions between the tumor and its microenvironement, more specifically the host's local immunity, and how the latter contributes to the biological behavior of the tumor. Among the immune cells (i.e., tumor-associated macrophages, dendritic cells, neutrophils, T cells and mast cells) in the microenvironment, mast cell has probably received the least attention despite well-established evidence for its roles in carcinogenesis [3].Mast cells originate from the bone marrow and the immatur
Evaluation of Pathogen Reduction Systems to Inactivate Dengue and Chikungunya Viruses in Apheresis Platelets Suspended in Plasma  [PDF]
Li Kiang Tan, Sally Lam, Swee Ling Low, Fang Hui Tan, Lee Ching Ng, Diana Teo
Advances in Infectious Diseases (AID) , 2013, DOI: 10.4236/aid.2013.31001

The risk of blood-borne transmission of infectious diseases has led to an increasing awareness of the need for a safe and effective pathogen reduction technology. This study evaluated the efficacy of 2 pathogen reduction systems to inactivate dengue virus (DENV-2) and chikungunya virus (CHIKV) spiked into apheresis platelets (APLT) concentrates. Double-dose APLT collections (n = 3) were split evenly into two units and spiked with 107 infectious units of DENV-2 or CHIKV. APLTs samples were assayed for viral infectivity before and after Amotosalen photochemical treatment (PCT) or Riboflavin pathogen reduction treatment (PRT). Viral infectivity was determined by plaque assays. Platelet (PLT) count, pH and residual S-59 were measured during the storage of 5 days. Amotosalen PCT showed robust efficacy and complete inactivation of both viruses in APLTs, with up to 3.01 and 3.75 log reductions of DENV-2 and CHIKV respectively. At similar initial concentrations, Riboflavin PRT showed complete inactivation of CHIKV with up to 3.73 log reduction, much higher efficacy than against DENV-2 where a log reduction of up to 1.58 was observed. All post-treated APLTs maintained acceptable PLT yields and quality parameters. This parallel study of 2 pathogen reduction systems demonstrates their efficacy in inactivating or reducing DENV and CHIKV in APLTs and reaffirms the usefulness of pathogen inactivation systems to ensure the safety in PLTs transfusion.

Tina Lim Swee KIM,Wong Kiet WAH,Tan Ai LEE
The Turkish Online Journal of Distance Education , 2007,
Abstract: This paper examines the practice of online discussion in a course specially tailored for in-service teachers who are pursuing their basic degree qualification at a teacher training institute. Analyses of postings to the asynchronous electronic discussion group were made according to the type of postings as proposed by Poole (2000). Four focus areas were looked into, that is, content, technical, procedural, or non-academic. Analyses were done for each quarter of the 12 weeks of interaction. At the end of the learners’ participation in the EDG and before their end-of-course examination, the participants were then given a paper-based questionnaire asking their perceptions on the use of EDG as part of their coursework on the whole. Six aspects of EDG were examined, these are; technical aspects, motivation to use the EDG, quality of interaction, tutor’s response, perceived learning, and attitude towards EDG. Analyses on postings for the EDG showed that the bulk of the postings were made in the last quarter of the online discussions. Further, 97.8% of the postings were on content and the types of content posting registered were predominantly questions (41.19%) and those that sought clarification/elaboration (37.48%). Findings from this study suggest that overall the participants were satisfied with the six aspects of EDG examined. The aspect that recorded the highest mean was ‘motivation to read tutor’s responses’ whilst the lowest mean (and the only one with negative perception) was for ‘worthiness of time spent on online discussions’.
Self-efficacy in Second/Foreign Language Learning Contexts
Saeid Raoofi,Bee Hoon Tan,Swee Heng Chan
English Language Teaching , 2012, DOI: 10.5539/elt.v5n11p60
Abstract: This study reviews the empirical literature of self-efficacy, a central component of social cognitive theory, in the area of second language learning by focusing on two research questions: first, to what extent, has self-efficacy, as a predicting variable, has been explored in the field of second language learning? Second, what factors affect learners’ self-efficacy beliefs in learning a foreign/second language? On addressing the research questions, 32 articles published between 2003 and 2012 were selected. The articles were classified into two main categories – effects of self-efficacy and factors affecting self-efficacy. Then each category was divided into certain subcategories for discussion. The findings of the review revealed that several factors enhance the level of students’ self-efficacy, and self-efficacy is a strong predictor of performance in different language skills and tasks. Limitations of the empirical studies discussed and directions for further investigation are also presented.
Long-Term Sorption of Metals Is Similar among Plastic Types: Implications for Plastic Debris in Aquatic Environments
Chelsea M. Rochman, Brian T. Hentschel, Swee J. Teh
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085433
Abstract: Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types.
The Chemical Composition and Biological Properties of Coconut (Cocos nucifera L.) Water
Jean W. H. Yong,Liya Ge,Yan Fei Ng,Swee Ngin Tan
Molecules , 2009, DOI: 10.3390/molecules14125144
Abstract: Coconut water (coconut liquid endosperm), with its many applications, is one of the world’s most versatile natural product. This refreshing beverage is consumed worldwide as it is nutritious and beneficial for health. There is increasing scientific evidence that supports the role of coconut water in health and medicinal applications. Coconut water is traditionally used as a growth supplement in plant tissue culture/micropropagation. The wide applications of coconut water can be justified by its unique chemical composition of sugars, vitamins, minerals, amino acids and phytohormones. This review attempts to summarise and evaluate the chemical composition and biological properties of coconut water.
An artifacts removal post-processing for epiphyseal region-of-interest (EROI) localization in automated bone age assessment (BAA)
Hum Chai, Lai Wee, Tan Swee, Sh-Hussain Salleh, Lim Chea
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-87
Abstract: A proposed method with anisotropic diffusion as pre-processing and a novel Bounded Area Elimination (BAE) post-processing algorithm to improve the algorithm of ossification site localization technique are designed with the intent of improving the adaptive segmentation result and the region-of interest (ROI) localization accuracy.The results are then evaluated by quantitative analysis and qualitative analysis using texture feature evaluation. The result indicates that the image homogeneity after anisotropic diffusion has improved averagely on each age group for 17.59%. Results of experiments showed that the smoothness has been improved averagely 35% after BAE algorithm and the improvement of ROI localization has improved for averagely 8.19%. The MSSIM has improved averagely 10.49% after performing the BAE algorithm on the adaptive segmented hand radiograph.The result indicated that hand radiographs which have undergone anisotropic diffusion have greatly reduced the noise in the segmented image and the result as well indicated that the BAE algorithm proposed is capable of removing the artifacts generated in adaptive segmentation.Bone age assessment (BAA) or bone maturity assessment is a clinical application used to evaluate the skeletal development especially in children and adolescents. Due to the inefficiency to describe maturation age using chronological age, the skeletal maturity or skeletal age is utilized as indicator for growth disorders as well as the predictor for final body height [1]. The radiograph of left hand is proven [2] to be a reliable indicator of skeletal maturation and therefore is used as the skeletal to represent the biological maturity depending on features like development of ossification area and calcium position in the ossification area. Diseases of children like endocrine disorders, chromosomal disorders, early sexual maturation, and others [3] can be detected via the discrepancy between the skeletal age and biological age.Basically there a
Weak expression of cyclooxygenase-2 is associated with poorer outcome in endemic nasopharyngeal carcinoma: analysis of data from randomized trial between radiation alone versus concurrent chemo-radiation (SQNP-01)
Susan Loong, Jacqueline Hwang, Hui Li, Joseph Wee, Swee Yap, Melvin Chua, Kam Fong, Terence Tan
Radiation Oncology , 2009, DOI: 10.1186/1748-717x-4-23
Abstract: 58 out of 88 patients from this institution had samples available for analysis. COX-2 expression levels were stratified by immunohistochemistry, into negligible, weak, moderate and strong, and correlated with overall and disease specific survivals.58% had negligible or weak COX-2 expression, while 14% and 28% had moderate and strong expression respectively. Weak COX-2 expression conferred a poorer median overall survival, 1.3 years for weak versus 6.3 years for negligible, 7.8 years, strong and not reached for moderate. There was a similar trend for disease specific survival.Contrary to literature published on other malignancies, our findings seemed to indicate that over-expression of COX-2 confer a better prognosis in patients with endemic NPC. Larger studies are required to conclusively determine the significance of COX-2 expression in these patients.Nasopharyngeal carcinoma (NPC) is the sixth most common male cancer in Singapore. The current standard of care for locally advanced NPC is concurrent chemo-radiation, which is associated with increased acute and long term morbidities [1,2]. Increasing effort has been directed toward developing molecular targeted therapies for the treatment of NPC with increasing interest in cyclooxygenase-2 (COX-2) inhibitors.COX-2 is a 68 kDA enzyme that catalyses the conversion of arachidonic acid to prostaglandins. Over-expression of COX-2 has been found in a variety of malignancies, both gastrointestinal (colon, oesophagus, stomach, pancreas) as well as outside the gastrointestinal tract (lung, breast, bladder and cervix), and shown to correlate with poorer outcomes [3-6].We hereby describe a retrospective analysis of 58 samples from patients, diagnosed with endemic NPC, who had previously been randomized into a trial of radiotherapy (RT) alone versus concurrent chemo-radiation (CRT) [7]. The aims of the study were to determine the expression level of COX-2 in our cohort of patients and to correlate this with known prognostic fact
A Microfluidic Device to Sort Cells Based on Dynamic Response to a Stimulus
Swee Jin Tan, Michelle Z. L. Kee, Ajay Sriram Mathuru, William F. Burkholder, Suresh J. Jesuthasan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078261
Abstract: Single cell techniques permit the analysis of cellular properties that are obscured by studying the average behavior of cell populations. One way to determine how gene expression contributes to phenotypic differences among cells is to combine functional analysis with transcriptional profiling of single cells. Here we describe a microfluidic device for monitoring the responses of single cells to a ligand and then collecting cells of interest for transcriptional profiling or other assays. As a test, cells from the olfactory epithelium of zebrafish were screened by calcium imaging to identify sensory neurons that were responsive to the odorant L-lysine. Single cells were subsequently recovered for transcriptional profiling by qRT-PCR. Responsive cells all expressed TRPC2 but not OMP, consistent with known properties of amino-acid sensitive olfactory neurons. The device can be adapted for other areas in biology where there is a need to sort and analyze cells based on their signaling responses.
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