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Search Results: 1 - 10 of 21740 matches for " Han Chong Toh "
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Immune Microenvironment in Tumor Progression: Characteristics and Challenges for Therapy
Valerie Chew,Han Chong Toh,Jean-Pierre Abastado
Journal of Oncology , 2012, DOI: 10.1155/2012/608406
Abstract: The tumor microenvironment plays a critical role in cancer development, progression, and control. The molecular and cellular nature of the tumor immune microenvironment influences disease outcome by altering the balance of suppressive versus cytotoxic responses in the vicinity of the tumor. Recent developments in systems biology have improved our understanding of the complex interactions between tumors and their immunological microenvironment in various human cancers. Effective tumor surveillance by the host immune system protects against disease, but chronic inflammation and tumor “immunoediting” have also been implicated in disease development and progression. Accordingly, reactivation and maintenance of appropriate antitumor responses within the tumor microenvironment correlate with a good prognosis in cancer patients. Improved understanding of the factors that shape the tumor microenvironment will be critical for the development of effective future strategies for disease management. The manipulation of these microenvironmental factors is already emerging as a promising tool for novel cancer treatments. In this paper, we summarize the various roles of the tumor microenvironment in cancer, focusing on immunological mediators of tumor progression and control, as well as the significant challenges for future therapies. 1. Introduction The tumor microenvironment consists of cancer cells, stromal tissue, and extracellular matrix. The immune system is an important determinant of the tumor microenvironment. Indeed, the complex interplay between cancer cells and the host immune response has been extensively investigated in the past few decades. Several immunological deficiencies have been linked with enhanced tumor development in mouse models as well as in humans [1, 2]. The higher incidence of cancers in transplant patients receiving long-term immunosuppressive treatment is well documented [3–5]. Similarly, mice with compromised immune functions due to genetic modifications develop more tumors [6–9]. It is now well recognized that effective tumor surveillance by the immune system is critical to maintain homeostasis in the host. Despite exerting a key role in host protection, tumor surveillance by the immune system may eventually fail. As described in the three “Es” of cancer immunoediting, tumor cells are initially eliminated by the immune system before becoming clinically detectable. This is then followed by an equilibrium phase, where a selection process for less immunogenic tumor variants take place until the tumors finally “escape” the immune
The utility of Aspirin in dukes C and high risk dukes B colorectal cancer - The ASCOLT study: study protocol for a randomized controlled trial
Raghib Ali, Han-Chong Toh, Whay-Kuang Chia, The ASCOLT trial investigators
Trials , 2011, DOI: 10.1186/1745-6215-12-261
Abstract: We hypothesize through this randomized, placebo-controlled adjuvant study, that Aspirin in patients with dukes C or high risk dukes B colorectal cancer (ASCOLT) can improve survival in this patient population over placebo control. The primary endpoint of this study is Disease Free Survival and the secondary Endpoint is 5 yr Overall Survival. This study will randomize eligible patients with Dukes C or high risk Dukes B colorectal cancer, after completion of surgery and standard adjuvant chemotherapy (+/- radiation therapy for rectal cancer patients) to 200 mg Aspirin or Placebo for 3 years. Stratification factors include study centre, rectal or colon cancer stage, and type of adjuvant chemotherapy (exposed/not exposed to oxaliplatin). After randomization, patient will be followed up with 3 monthly assessments whilst on study drug and for a total of 5 years. Patients with active peptic ulcer disease, bleeding diathesis or on treatment with aspirin or anti-platelet agents will be excluded from the study.This study aims to evaluate Aspirin's role as an adjuvant treatment in colorectal cancer. If indeed found to be beneficial, because aspirin is cheap, accessible and easy to administer, it will positively impact the lives of many individuals in Asia and globally.Clinicaltrials.gov: NCT00565708Colorectal cancer is the third most common cancer worldwide with almost 1 million new cases diagnosed each year. It is now also the third leading cause of cancer mortality in men and women with more than half of diagnosed patients dying from the disease [1]. Over the past 3 decades, the age-standardized incidence rate for colorectal cancer has increased two to fourfold in Asian countries such as China, Japan, South Korea and Singapore [2]. Mortality rates in Asian countries have risen concomitantly and in Singapore colon cancer has recently surpassed lung cancer as the commonest cancer with incidence rates now amongst the highest in Asia [3].With the rising rates of cancer, a fundam
Capecitabine with radiation is an effective adjuvant therapy in gastric cancers
Chee Kian Tham, Su Pin Choo, Donald Yew Hee Poon, Han Chong Toh, Simon Yew Kuang Ong, Sze Huey Tan, Michael Lian Chek Wang, Kian Fong Foo
World Journal of Gastroenterology , 2010,
Abstract: AIM: To analyze the outcome of patients who received concurrent capecitabine (Xeloda) and radiation (XRT) compared to the established concurrent 5-fluorouracil (5-FU) with radiation (5FU-RT) and fluoropyrimidine-based chemotherapy alone as adjuvant treatment in gastric cancers.METHODS: All patients with gastric cancers who received adjuvant treatment at the National Cancer Centre Singapore between 1996 and 2006 were reviewed. Treatment outcomes of patients who received XRT were compared with those who had 5FU-RT or chemotherapy alone as adjuvant therapy for gastric cancers.RESULTS: A total of 108 patients were reviewed. Median age at diagnosis was 60. The majority of the patients (64.8%) had advanced stage III and IV disease (with no distant metastasis). All except 4 patients had D2 gastrectomy. Twenty one patients (19.4%) had positive surgical resection margins. Thirty three patients received XRT compared with 52 who had 5FU-RT and 23 who received chemotherapy alone. For the patients in the chemotherapy-only group, all had fluoropyrimidine-based therapy, with added cisplatin in 7 patients and epirubicin in 2 patients. Median recurrence-free survival was longer for the XRT group (52 mo) compared to the 5FU-RT (35 mo) and chemotherapy-only groups (25 mo) (P = 0.48). The patients in the XRT group achieved similar median overall survival (53 mo) as the 5FU-RT (54 mo) and the chemotherapy-only groups (44 mo) (P = 0.5).CONCLUSION: Capecitabine with concurrent radiation was as effective as concurrent 5FU with radiation or fluoropyrimidine-based chemotherapy alone when used as adjuvant treatment in patients with gastric cancers.
MicroRNA-224 Targets SMAD Family Member 4 to Promote Cell Proliferation and Negatively Influence Patient Survival
Yu Wang, Jianwei Ren, Yun Gao, Joel Z. I. Ma, Han Chong Toh, Pierce Chow, Alexander Y. F. Chung, London L. P. J. Ooi, Caroline G. L. Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068744
Abstract: MicroRNA-224 (miR-224) is frequently over-expressed in liver and colorectal cancers. We and others have previously described the role of miR-224 over-expression in cell proliferation in vitro but we have yet to identify the relevant miR-224 direct target. In this study, we further demonstrated that miR-224 up-regulation promotes cell proliferation using both in vitro assays and in vivo tumor growth models. We systematically screened for high confidence miR-224 targets by overlapping in silico predicted targets from multiple algorithms and significantly down-regulated genes in miR-224-expressing cells from whole genome expression microarrays. A total of 72 high confidence miR-224 targets were identified and found to be enriched in various cancer-related processes. SMAD family member 4 (SMAD4) is experimentally validated as the direct cellular target through which miR-224 promotes cell proliferation. The clinical relevance of our experimental observations was supported by a statistically significant inverse correlation between miR-224 and SMAD4 transcript expression in tumor versus paired adjacent non-tumorous tissues from HCC patients (p<0.001, r = ?0.45, R2 = 0.122). Furthermore, miR-224 up-regulation and SMAD4 down-regulation is significantly associated with poorer patient survival (p<0.05). In summary, miR-224/SMAD4 pathway is a clinically relevant pathway to provide new insights in understanding HCC. (191 words).
Identification of Serum Monocyte Chemoattractant Protein-1 and Prolactin as Potential Tumor Markers in Hepatocellular Carcinoma
Who-Whong Wang, Soo Fan Ang, Rajneesh Kumar, Charmain Heah, Andi Utama, Navessa Padma Tania, Huihua Li, Sze Huey Tan, Desmond Poo, Su Pin Choo, Wan Cheng Chow, Chee Kiat Tan, Han Chong Toh
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068904
Abstract: Early diagnosis of hepatocellullar carcinoma (HCC) remains a challenge. The current practice of serum alpha-fetoprotein (AFP) measurement is inadequate. Here we utilized a proteomic approach to identify novel serum biomarkers for distinguishing HCC patients from non-cancer controls. We profiled the serum proteins in a group of 58 resectable HCC patients and 11 non-HCC chronic hepatitis B (HBV) carrier samples from the Singapore General Hospital (SGH) using the RayBio? L-Series 507 Antibody Array and found 113 serum markers that were significantly modulated between HCC and control groups. Selected potential biomarkers from this list were quantified using a multiplex sandwich enzyme-linked immunosorbent assay (ELISA) array in an expanded SGH cohort (126 resectable HCC patients and 115 non-HCC chronic HBV carriers (NC group)), confirming that serum prolactin and monocyte chemoattractant protein-1 (MCP-1) were significantly upregulated in HCC patients. This finding of serum MCP-1 elevation in HCC patients was validated in a separate cohort of serum samples from the Mochtar Riady Institute for Nanotechnology, Indonesia (98 resectable HCC, 101 chronic hepatitis B patients and 100 asymptomatic HBV/HCV carriers) by sandwich ELISA. MCP-1 and prolactin levels were found to correlate with AFP, while MCP-1 also correlated with disease stage. Subsequent receiver operating characteristic (ROC) analysis of AFP, prolactin and MCP-1 in the SGH cohort and comparing their area under the ROC curve (AUC) indicated that neither prolactin nor MCP-1 on their own performed better than AFP. However, the combination of AFP+MCP-1 (AUC, 0.974) had significantly superior discriminative ability than AFP alone (AUC, 0.942; p<0.001). In conclusion, prolactin and MCP-1 are overexpressed in HCC and are conveniently quantifiable in patients’ sera by ELISA. MCP-1 appears to be a promising complementary biomarker for HCC diagnosis and this MCP-1+AFP model should be further evaluated as potential biomarker on a larger scale in patients at-risk of HCC.
Tangible Objects: The Missing Attribute in Multimedia Learning Systems for Preschoolers
Chau Kien Tsong,Lili Budiman,Toh Seong Chong,Zarina Samsudin
International Journal of Multimedia & Its Applications , 2012,
Abstract: Based on the idea of constructivism, cognitivism, Atkinson & Shiffrin and Kieras & Meyer’s EPIC human memory theories, tangible objects are considered the missing attribute in digital multimedia learning systems for preschoolers. Because of negligence to this attribute, a learning gap emerges between preschoolers and multimedia system. The gap is reflected in the cognitive capability of a preschooler whose cognition is still in a state of preoperational level and the condition of multimedia which only delivers information in digital visual-auditory format. In light of the four compelling theories, a multimedia prototype augmented with the use of tangible objects named “TangiLearn” has been designed. In this paper, we begin our discussion by visiting the idea of tangibility brought forward by the theories, followed by a relevant pilot study to illustrate a successful innovation in closing the learning gap.
Augmenting the Post-Transplantation Growth and Survivorship of Juvenile Scleractinian Corals via Nutritional Enhancement
Tai Chong Toh, Chin Soon Lionel Ng, Jia Wei Kassler Peh, Kok Ben Toh, Loke Ming Chou
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098529
Abstract: Size-dependant mortality influences the recolonization success of juvenile corals transplanted for reef restoration and assisting juvenile corals attain a refuge size would thus improve post-transplantation survivorship. To explore colony size augmentation strategies, recruits of the scleractinian coral Pocillopora damicornis were fed with live Artemia salina nauplii twice a week for 24 weeks in an ex situ coral nursery. Fed recruits grew significantly faster than unfed ones, with corals in the 3600, 1800, 600 and 0 (control) nauplii/L groups exhibiting volumetric growth rates of 10.65±1.46, 4.69±0.9, 3.64±0.55 and 1.18±0.37 mm3/week, respectively. Corals supplied with the highest density of nauplii increased their ecological volume by more than 74 times their initial size, achieving a mean final volume of 248.38±33.44 mm3. The benefits of feeding were apparent even after transplantation to the reef. The corals in the 3600, 1800, 600 and 0 nauplii/L groups grew to final sizes of 4875±260 mm3, 2036±627 mm3, 1066±70 mm3 and 512±116 mm3, respectively. The fed corals had significantly higher survival rates than the unfed ones after transplantation (63%, 59%, 56% and 38% for the 3600, 1800, 600 and 0 nauplii/L treatments respectively). Additionally, cost-effectiveness analysis revealed that the costs per unit volumetric growth were drastically reduced with increasing feed densities. Corals fed with the highest density of nauplii were the most cost-effective (US$0.02/mm3), and were more than 12 times cheaper than the controls. This study demonstrated that nutrition enhancement can augment coral growth and post-transplantation survival, and is a biologically and economically viable option that can be used to supplement existing coral mariculture procedures and enhance reef restoration outcomes.
Protection Strategies against Cascading Failure for Power Systems of Ring Network  [PDF]
Arun Kumar, Hnin Yu Shwe, Peter Han Joo Chong
Communications and Network (CN) , 2016, DOI: 10.4236/cn.2016.82008
Abstract: Power grid vulnerability is a key issue with large blackouts, causing power disruption for millions of people. The complexity of power grid, together with excessive number of components, makes it difficult to be modeled. Currently, researchers use complex networks to model and study the performance of power grids. In fact, power grids can be modeled into a complex network by making use of ring network topology, with substations and transmission lines denoted as nodes and edges, respectively. In this paper, three protection schemes are proposed and their effectiveness in protecting the power network under high and low-load attacks is studied. The proposed schemes, namely, Cascaded Load Cut-off (CLC), Cascaded Load Overflow (CLO) and Adaptive-Cascaded Load Overflow (A-CLO), improve the robustness of the power grids, i.e., decrease the value of critical tolerance. Simulation results show that CLC and CLO protection schemes are more effective in improving the robustness of networks than the A-CLO protection scheme. However, the CLC protection scheme is effective only at the expense that certain percentage of the network will have no power supply. Thus, results show that the CLO protection scheme dominates the other protection schemes, CLC and A-CLO, in terms of the robustness of the network, improved with the precise amount of load cut-off determined.
Visualizing A Framework for Tangibility in Multimedia Learning for Preschoolers
Chau Kien Tsong,Toh Seong Chong,Zarina Samsudin,Wan Ahmad Jaafar Wan Yahaya
International Journal of Multimedia & Its Applications , 2012,
Abstract: This paper represents an attempt to conceive a tangible multimedia framework in educational settings. For preschoolers, the major drawback in conventional multimedia systems nowadays is the lack of concrete elements that allow them to learn naturally and tangibly. As Piaget stated that children aged below seven can only cognizant concrete objects (preoperational stage), there exists a large gap between preschoolers and digital multimedia. To bridge the gap, multimedia should and need to embrace tangible objects in learning. However, as a newly explored area, there is absence of discussion on how the tangible multimedia should look like. In response to this, a relevant framework that outlines the basic structure of such multimedia is visualized in this paper for reference as well as grounding guidelines. Relevant pilot study conducted revealed that tangible multimedia was efficacious in elevating preschoolers’ learning performance, and motivation.
Implementation Study of a Centralized Routing Protocol for Data Acquisition in Wireless Sensor Networks  [PDF]
Trung Hieu Pham, Xue Jun Li, Wai Yee Leong, Peter Han Joo Chong
Wireless Sensor Network (WSN) , 2011, DOI: 10.4236/wsn.2011.35019
Abstract: Wireless sensor networks (WSNs) attract considerable amount of research efforts from both industry and academia. With limited power and computational capability available on a sensor node, robustness and efficiency are the main concerns when designing a routing protocol for WSNs with low complexity. There are various existing design approaches, such as data-centric approach, hierarchical approach and location-based approach, which were designed for a particular application with specific requirements. In this paper, we study the design and implementation of a routing protocol for data acquisition in WSNs. The designed routing protocol is named Centralized Sensor Protocol for Information via Negotiation (CSPIN), which essentially combines the advertise-request-transfer process and a routing distribution mechanism. Implementation is realized and demonstrated with the Crossbow MicaZ hardware using nesC/TinyOS. It was our intention to provide a hand-on study of implementation of centralized routing protocol for WSNs.
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