67 results on '"Wan WK"'
Search Results
2. A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve
- Author
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Robert J. Klassen, Wan Wk, and Hadi Mohammadi
- Subjects
Water hammer ,Materials science ,business.industry ,Mechanical Engineering ,Finite Element Analysis ,Fracture mechanics ,General Medicine ,Structural engineering ,Models, Theoretical ,Finite element method ,Prosthesis Failure ,Catastrophic failure ,Aortic Valve ,Heart Valve Prosthesis ,Cavitation ,Computer-Aided Design ,Humans ,Computer Simulation ,Stress, Mechanical ,Impact ,business ,Boundary element method ,Stress intensity factor - Abstract
Pyrolytic carbon mechanical heart valves (MHVs) are widely used to replace dysfunctional and failed heart valves. As the human heart beats around 40 million times per year, fatigue is the prime mechanism of mechanical failure. In this study, a finite element approach is implemented to develop a model for fatigue analysis of MHVs due to the impact force between the leaflet and the stent and cavitation in the aortic position. A two-step method to predict crack propagation in the leaflets of MHVs has been developed. Stress intensity factors (SIFs) are computed at a small initiated crack located on the leaflet edge (the worst case) using the boundary element method (BEM). Static analysis of the crack is performed to analyse the stress distribution around the front crack zone when the crack is opened; this is followed by a dynamic crack analysis to consider crack propagation using the finite element approach. Two factors are taken into account in the calculation of the SIFs: first, the effect of microjet formation due to cavitation in the vicinity of leaflets, resulting in water hammer pressure; second, the effect of the impact force between the leaflet and the stent of the MHVs, both in the closing phase. The critical initial crack length, the SIFs, the water hammer pressure, and the maximum jet velocity due to cavitation have been calculated. With an initial crack length of 35 μm, the fatigue life of the heart valve is greater than 60 years (i.e. about 2.2×109 cycles) and, with an initial crack length of 170 μm, the fatigue life of the heart valve would be around 2.5 years (i.e. about 9.1×107 cycles). For an initial crack length greater than 170 μm, there is catastrophic failure and fatigue cracking no longer occurs. A finite element model of fatigue analysis using Patran command language (PCL custom code) in MSC software can be used to evaluate the useful lifespan of MHVs. Similar methodologies can be extended to other medical devices under cyclic loads.
- Published
- 2008
3. Novel phase behavior in normal alkanes
- Author
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Hughes Gj, Wan Wk, Hubert E. King, and Eric B. Sirota
- Subjects
Materials science ,business.industry ,Hexagonal phase ,General Physics and Astronomy ,Order (ring theory) ,Crystal ,Crystallography ,Optics ,Liquid crystal ,Phase (matter) ,Orthorhombic crystal system ,Plastic crystal ,business ,Phase diagram - Abstract
X-ray scattering studies on aligned films of binary mixtures of the normal alkanes C{sub 23}H{sub 48} and C{sub 28}H{sub 58} reveal, for the first time in such materials, the existence of a new equilibrium phase having the symmetry of a smectic crystal, possibly a hexatic. This phase occurs between the hexagonally packed {ital R}{sub II} and the lower-temperature orthorhombic {ital R}{sub I}, plastic crystalline, layered, rotator phases. We argue that this loss of order is due to local distortion fluctuations in the hexagonal phase. Furthermore, we have identified an {ital ABC}-to-{ital ABAB} restacking transition within the ordered {ital R}{sub II} phase.
- Published
- 1992
4. Design and simulation of a poly(vinyl alcohol)-bacterial cellulose nanocomposite mechanical aortic heart valve prosthesis.
- Author
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Mohammadi H, Boughner D, Millon LE, Wan WK, Mohammadi, H, Boughner, D, Millon, L E, and Wan, W K
- Abstract
In this study, a polymeric aortic heart valve made of poly(vinyl alcohol) (PVA)-bacterial cellulose (BC) nanocomposite is simulated and designed using a hyperelastic non-linear anisotropic material model. A novel nanocomposite biomaterial combination of 15 wt % PVA and 0.5 wt % BC is developed in this study. The mechanical properties of the synthesized PVA-BC are similar to those of the porcine heart valve in both the principal directions. To design the geometry of the leaflets an advance surfacing technique is employed. A Galerkin-based non-linear finite element method is applied to analyse the mechanical behaviour of the leaflet in the closing and opening phases under physiological conditions. The model used in this study can be implemented in mechanical models for any soft tissues such as articular cartilage, tendon, and ligament. [ABSTRACT FROM AUTHOR]
- Published
- 2009
5. A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve.
- Author
-
Mohammadi H, Klassen RJ, Wan WK, Mohammadi, H, Klassen, R J, and Wan, W-K
- Abstract
Pyrolytic carbon mechanical heart valves (MHVs) are widely used to replace dysfunctional and failed heart valves. As the human heart beats around 40 million times per year, fatigue is the prime mechanism of mechanical failure. In this study, a finite element approach is implemented to develop a model for fatigue analysis of MHVs due to the impact force between the leaflet and the stent and cavitation in the aortic position. A two-step method to predict crack propagation in the leaflets of MHVs has been developed. Stress intensity factors (SIFs) are computed at a small initiated crack located on the leaflet edge (the worst case) using the boundary element method (BEM). Static analysis of the crack is performed to analyse the stress distribution around the front crack zone when the crack is opened; this is followed by a dynamic crack analysis to consider crack propagation using the finite element approach. Two factors are taken into account in the calculation of the SIFs: first, the effect of microjet formation due to cavitation in the vicinity of leaflets, resulting in water hammer pressure; second, the effect of the impact force between the leaflet and the stent of the MHVs, both in the closing phase. The critical initial crack length, the SIFs, the water hammer pressure, and the maximum jet velocity due to cavitation have been calculated. With an initial crack length of 35 microm, the fatigue life of the heart valve is greater than 60 years (i.e. about 2.2 x 10(9) cycles) and, with an initial crack length of 170 microm, the fatigue life of the heart valve would be around 2.5 years (i.e. about 9.1 x 10(7) cycles). For an initial crack length greater than 170 microm, there is catastrophic failure and fatigue cracking no longer occurs. A finite element model of fatigue analysis using Patran command language (PCL custom code) in MSC software can be used to evaluate the useful lifespan of MHVs. Similar methodologies can be extended to other medical devices under cyclic loads. [ABSTRACT FROM AUTHOR]
- Published
- 2008
6. A multimodal atlas of hepatocellular carcinoma reveals convergent evolutionary paths and 'bad apple' effect on clinical trajectory.
- Author
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Chen J, Kaya NA, Zhang Y, Kendarsari RI, Sekar K, Lee Chong S, Seshachalam VP, Ling WH, Jin Phua CZ, Lai H, Yang H, Lu B, Lim JQ, Ma S, Chew SC, Chua KP, Santiago Alvarez JJ, Wu L, Ooi L, Yaw-Fui Chung A, Cheow PC, Kam JH, Wei-Chieh Kow A, Ganpathi IS, Bunchaliew C, Thammasiri J, Koh PS, Bee-Lan Ong D, Lim J, de Villa VH, Dela Cruz RD, Loh TJ, Wan WK, Leow WQ, Yang Y, Liu J, Skanderup AJ, Pang YH, Ting Soon GS, Madhavan K, Kiat-Hon Lim T, Bonney G, Goh BKP, Chew V, Dan YY, Toh HC, Sik-Yin Foo R, Tam WL, Zhai W, and Kah-Hoe Chow P
- Subjects
- Aged, Female, Humans, Male, Middle Aged, DNA Copy Number Variations, Evolution, Molecular, Mutation, Prognosis, Prospective Studies, Carcinoma, Hepatocellular genetics, Carcinoma, Hepatocellular pathology, Carcinoma, Hepatocellular mortality, Liver Neoplasms genetics, Liver Neoplasms pathology, Liver Neoplasms mortality, Transcriptome
- Abstract
Background & Aims: Hepatocellular carcinoma (HCC) is a highly fatal cancer characterized by high intra-tumor heterogeneity (ITH). A panoramic understanding of its tumor evolution, in relation to its clinical trajectory, may provide novel prognostic and treatment strategies., Methods: Through the Asia-Pacific Hepatocellular Carcinoma trials group (NCT03267641), we recruited one of the largest prospective cohorts of patients with HCC, with over 600 whole genome and transcriptome samples from 123 treatment-naïve patients., Results: Using a multi-region sampling approach, we revealed seven convergent genetic evolutionary paths governed by the early driver mutations, late copy number variations and viral integrations, which stratify patient clinical trajectories after surgical resection. Furthermore, such evolutionary paths shaped the molecular profiles, leading to distinct transcriptomic subtypes. Most significantly, although we found the coexistence of multiple transcriptomic subtypes within certain tumors, patient prognosis was best predicted by the most aggressive cell fraction of the tumor, rather than by overall degree of transcriptomic ITH level - a phenomenon we termed the 'bad apple' effect. Finally, we found that characteristics throughout early and late tumor evolution provide significant and complementary prognostic power in predicting patient survival., Conclusions: Taken together, our study generated a comprehensive landscape of evolutionary history for HCC and provides a rich multi-omics resource for understanding tumor heterogeneity and clinical trajectories., Impact and Implications: This prospective study, utilizing comprehensive multi-sector, multi-omics sequencing and clinical data from surgically resected hepatocellular carcinoma (HCC), reveals critical insights into the role of tumor evolution and intra-tumor heterogeneity (ITH) in determining the prognosis of HCC. These findings are invaluable for oncology researchers and clinicians, as they underscore the influence of distinct evolutionary paths and the 'bad apple' effect, where the most aggressive tumor fraction dictates disease progression. These insights not only enhance prognostic accuracy post-surgical resection but also pave the way for personalized treatment strategies tailored to specific tumor evolutionary and transcriptomic profiles. The coexistence of multiple subtypes within the same tumor prompts a re-appraisal of the utilities of depending on single samples to represent the entire tumor and suggests the need for clinical molecular imaging. This research thus marks a significant step forward in the clinical understanding and management of HCC, underscoring the importance of integrating tumor evolutionary dynamics and multi-omics biomarkers into therapeutic decision-making., Clinical Trial Number: NCT03267641 (Observational cohort)., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
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7. GATA4 downregulation enhances CCL20-mediated immunosuppression in hepatocellular carcinoma.
- Author
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Nasir NJM, Chuah S, Shuen T, Prawira A, Ba R, Lim MC, Chua J, Nguyen PHD, Lim CJ, Wasser M, Hazirah SN, Lim TKH, Leow WQ, Loh TJ, Wan WK, Pang YH, Soon G, Cheow PC, Kam JH, Iyer S, Kow A, Dan YY, Bonney GK, Chung A, Goh BKP, Chow PKH, Albani S, Zhai W, Ouyang JF, Toh HC, and Chew V
- Subjects
- Humans, Gene Expression Regulation, Neoplastic, Immune Tolerance, Myeloid-Derived Suppressor Cells immunology, Male, T-Lymphocytes, Regulatory immunology, Carcinoma, Hepatocellular immunology, Carcinoma, Hepatocellular genetics, Carcinoma, Hepatocellular mortality, Liver Neoplasms immunology, Liver Neoplasms genetics, Liver Neoplasms mortality, Liver Neoplasms pathology, GATA4 Transcription Factor genetics, Chemokine CCL20 genetics, Down-Regulation, Tumor Microenvironment immunology
- Abstract
Background: Hepatocellular carcinoma (HCC) is a deadly cancer with a high global mortality rate, and the downregulation of GATA binding protein 4 (GATA4) has been implicated in HCC progression. In this study, we investigated the role of GATA4 in shaping the immune landscape of HCC., Methods: HCC tumor samples were classified into "low" or "normal/high" based on GATA4 RNA expression relative to adjacent non-tumor liver tissues. The immune landscapes of GATA4-low and GATA4-normal/high tumors were analyzed using cytometry by time-of-flight, bulk/spatial transcriptomic analyses and validated by multiplex immunofluorescence., Results: GATA4-low tumors displayed enrichment in exhausted programmed cell death protein 1+ T cells, immunosuppressive regulatory T cells, myeloid-derived suppressor cells, and macrophages, highlighting the impact of GATA4 downregulation on immunosuppression. Spatial and bulk transcriptomic analyses revealed a negative correlation between GATA4 and C-C Motif Chemokine Ligand 20 (CCL20) expression in HCC. Overexpressing GATA4 confirmed CCL20 as a downstream target, contributing to an immunosuppressive tumor microenvironment, as evidenced by increased regulatory T cells and myeloid-derived suppressor cells in CCL20-high tumors. Lastly, the reduced expression of GATA4 and higher expression of CCL20 were associated with poorer overall survival in patients with HCC, implicating their roles in tumor progression., Conclusions: Our study reveals that GATA4 downregulation contributes to an immunosuppressive microenvironment, driven by CCL20-mediated enrichment of regulatory T cells and myeloid-derived suppressor cells in HCC. These findings underscore the critical role of GATA4 reduction in promoting immunosuppression and HCC progression., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Association for the Study of Liver Diseases.)
- Published
- 2024
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8. A genomic enhancer signature associates with hepatocellular carcinoma prognosis.
- Author
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Jeon AJ, Anene-Nzelu CG, Teo YY, Chong SL, Sekar K, Wu L, Chew SC, Chen J, Kendarsari RI, Lai H, Ling WH, Kaya NA, Lim JQ, Chung AYF, Cheow PC, Kam JH, Madhavan K, Kow A, Ganpathi IS, Lim TKH, Leow WQ, Loong S, Loh TJ, Wan WK, Soon GST, Pang YH, Yoong BK, Bee-Lan Ong D, Lim J, de Villa VH, Dela Cruz RD, Chanwat R, Thammasiri J, Bonney GK, Goh BKP, Foo RSY, and Chow PK
- Abstract
Background & Aims: Lifestyle and environmental-related exposures are important risk factors for hepatocellular carcinoma (HCC), suggesting that epigenetic dysregulation significantly underpins HCC. We profiled 30 surgically resected tumours and the matched adjacent normal tissues to understand the aberrant epigenetic events associated with HCC., Methods: We identified tumour differential enhancers and the associated genes by analysing H3K27 acetylation (H3K27ac) chromatin immunoprecipitation sequencing (ChIP-seq) and Hi-C/HiChIP data from the resected tumour samples of 30 patients with early-stage HCC. This epigenome dataset was analysed with previously reported genome and transcriptome data of the overlapping group of patients from the same cohort. We performed patient-specific differential expression testing using multiregion sequencing data to identify genes that undergo both enhancer and gene expression changes. Based on the genes selected, we identified two patient groups and performed a recurrence-free survival analysis., Results: We observed large-scale changes in the enhancer distribution between HCC tumours and the adjacent normal samples. Many of the gain-in-tumour enhancers showed corresponding upregulation of the associated genes and vice versa , but much of the enhancer and gene expression changes were patient-specific. A subset of the upregulated genes was activated in a subgroup of patients' tumours. Recurrence-free survival analysis revealed that the patients with a more robust upregulation of those genes showed a worse prognosis., Conclusions: We report the genomic enhancer signature associated with differential prognosis in HCC. Findings that cohere with oncofoetal reprogramming in HCC were underpinned by genome-wide enhancer rewiring. Our results present the epigenetic changes in HCC that offer the rational selection of epigenetic-driven gene targets for therapeutic intervention or disease prognostication in HCC., Impact and Implications: Lifestyle and environmental-related exposures are the important risk factors of hepatocellular carcinoma (HCC), suggesting that tumour-associated epigenetic dysregulations may significantly underpin HCC. We profiled tumour tissues and their matched normal from 30 patients with early-stage HCC to study the dysregulated epigenetic changes associated with HCC. By also analysing the patients' RNA-seq and clinical data, we found the signature genes - with epigenetic and transcriptomic dysregulation - associated with worse prognosis. Our findings suggest that systemic approaches are needed to consider the surrounding cellular environmental and epigenetic changes in HCC tumours., Competing Interests: The authors declare no potential conflicts of interest. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2023 The Author(s).)
- Published
- 2023
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9. Multi-region sampling with paired sample sequencing analyses reveals sub-groups of patients with novel patient-specific dysregulation in Hepatocellular Carcinoma.
- Author
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Jeon AJ, Teo YY, Sekar K, Chong SL, Wu L, Chew SC, Chen J, Kendarsari RI, Lai H, Ling WH, Kaya NA, Lim JQ, Ramasamy A, Oguz G, Chung AY, Chan CY, Cheow PC, Kam JH, Madhavan K, Kow A, Ganpathi IS, Lim TKH, Leow WQ, Loong S, Loh TJ, Wan WK, Soon GST, Pang YH, Yoong BK, Ong DB, Lim J, de Villa VH, Cruz RDD, Chanwat R, Thammasiri J, Bonney GK, Goh BKP, Tucker-Kellogg G, Foo RSY, and Chow PKH
- Subjects
- Humans, Biomarkers, Tumor genetics, Biomarkers, Tumor metabolism, Prognosis, Gene Expression Regulation, Neoplastic, Carcinoma, Hepatocellular genetics, Carcinoma, Hepatocellular pathology, Liver Neoplasms genetics, Liver Neoplasms pathology
- Abstract
Background: Conventional differential expression (DE) testing compares the grouped mean value of tumour samples to the grouped mean value of the normal samples, and may miss out dysregulated genes in small subgroup of patients. This is especially so for highly heterogeneous cancer like Hepatocellular Carcinoma (HCC)., Methods: Using multi-region sampled RNA-seq data of 90 patients, we performed patient-specific differential expression testing, together with the patients' matched adjacent normal samples., Results: Comparing the results from conventional DE analysis and patient-specific DE analyses, we show that the conventional DE analysis omits some genes due to high inter-individual variability present in both tumour and normal tissues. Dysregulated genes shared in small subgroup of patients were useful in stratifying patients, and presented differential prognosis. We also showed that the target genes of some of the current targeted agents used in HCC exhibited highly individualistic dysregulation pattern, which may explain the poor response rate., Discussion/conclusion: Our results highlight the importance of identifying patient-specific DE genes, with its potential to provide clinically valuable insights into patient subgroups for applications in precision medicine., (© 2023. The Author(s).)
- Published
- 2023
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10. IFNγ - IL-17 + CD8 T cells contribute to immunosuppression and tumor progression in human hepatocellular carcinoma.
- Author
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Lee YH, Chuah S, Nguyen PHD, Lim CJ, Lai HLH, Wasser M, Chua C, Lim TKH, Leow WQ, Loh TJ, Wan WK, Pang YH, Soon G, Cheow PC, Kam JH, Iyer S, Kow A, Bonney GK, Chan CY, Chung A, Goh BKP, Zhai W, Chow PKH, Albani S, Liu H, and Chew V
- Subjects
- Humans, CD8-Positive T-Lymphocytes, Interferon-gamma, Interleukin-17 genetics, Proteomics, Carcinoma, Hepatocellular immunology, Carcinoma, Hepatocellular pathology, Immune Tolerance, Liver Neoplasms immunology, Liver Neoplasms pathology
- Abstract
IL-17-producing CD8 (Tc17) T cells have been shown to play an important role in infection and chronic inflammation, however their implications in hepatocellular carcinoma (HCC) remain elusive. In this study, we performed cytometry by time-of-flight (CyTOF) and revealed the distinctive immunological phenotypes of two IFNγ
+ and IFNγ- Tc17 subsets that were preferentially enriched in human HCC. Single-cell RNA-sequencing analysis further revealed regulatory circuits governing the different phenotypes of these Tc17 subsets. In particular, we discovered that IFNγ- Tc17 subset demonstrated pro-tumoral characteristics and expressed higher levels of CCL20. This corresponded to increased tumor infiltration of T regulatory cells (Treg) validated by immunohistochemistry in another independent HCC cohort, demonstrating the immunosuppressive functions of IFNγ- Tc17 subset. Most importantly, higher intra-tumoral proportions of IFNγ- Tc17 were associated with poorer prognosis in patients with HCC and this was further validated in The Cancer Genome Atlas (TCGA) HCC cohort. Taken together, this compendium of transcriptomic and proteomic data of Tc17 subsets sheds light on the immunosuppressive phenotypes of IFNγ- Tc17 and its implications in HCC progression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2023
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11. Hypoxia-driven immunosuppression by Treg and type-2 conventional dendritic cells in HCC.
- Author
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Suthen S, Lim CJ, Nguyen PHD, Dutertre CA, Lai HLH, Wasser M, Chua C, Lim TKH, Leow WQ, Loh TJ, Wan WK, Pang YH, Soon G, Cheow PC, Kam JH, Iyer S, Kow A, Tam WL, Shuen TWH, Toh HC, Dan YY, Bonney GK, Chan CY, Chung A, Goh BKP, Zhai W, Ginhoux F, Chow PKH, Albani S, and Chew V
- Subjects
- Humans, T-Lymphocytes, Regulatory, Granzymes metabolism, CD8-Positive T-Lymphocytes, Programmed Cell Death 1 Receptor metabolism, Ligands, Tumor Microenvironment, Immunosuppression Therapy, Hypoxia metabolism, Dendritic Cells metabolism, HLA Antigens, Carcinoma, Hepatocellular pathology, Liver Neoplasms pathology
- Abstract
Background and Aims: Hypoxia is one of the central players in shaping the immune context of the tumor microenvironment (TME). However, the complex interplay between immune cell infiltrates within the hypoxic TME of HCC remains to be elucidated., Approach and Results: We analyzed the immune landscapes of hypoxia-low and hypoxia-high tumor regions using cytometry by time of light, immunohistochemistry, and transcriptomic analyses. The mechanisms of immunosuppression in immune subsets of interest were further explored using in vitro hypoxia assays. Regulatory T cells (Tregs) and a number of immunosuppressive myeloid subsets, including M2 macrophages and human leukocyte antigen-DR isotype (HLA-DR
lo ) type 2 conventional dendritic cell (cDC2), were found to be significantly enriched in hypoxia-high tumor regions. On the other hand, the abundance of active granzyme Bhi PD-1lo CD8+ T cells in hypoxia-low tumor regions implied a relatively active immune landscape compared with hypoxia-high regions. The up-regulation of cancer-associated genes in the tumor tissues and immunosuppressive genes in the tumor-infiltrating leukocytes supported a highly pro-tumorigenic network in hypoxic HCC. Chemokine genes such as CCL20 (C-C motif chemokine ligand 20) and CXCL5 (C-X-C motif chemokine ligand 5) were associated with recruitment of both Tregs and HLA-DRlo cDC2 to hypoxia-high microenvironments. The interaction between Tregs and cDC2 under a hypoxic TME resulted in a loss of antigen-presenting HLA-DR on cDC2., Conclusions: We uncovered the unique immunosuppressive landscapes and identified key immune subsets enriched in hypoxic HCC. In particular, we identified a potential Treg-mediated immunosuppression through interaction with a cDC2 subset in HCC that could be exploited for immunotherapies., (© 2022 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)- Published
- 2022
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12. Trajectory of immune evasion and cancer progression in hepatocellular carcinoma.
- Author
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Nguyen PHD, Wasser M, Tan CT, Lim CJ, Lai HLH, Seow JJW, DasGupta R, Phua CZJ, Ma S, Yang J, Suthen SD, Tam WL, Lim TKH, Yeong J, Leow WQ, Pang YH, Soon G, Loh TJ, Wan WK, Chan CY, Cheow PC, Toh HC, Kow A, Dan YY, Kam JH, Iyer S, Madhavan K, Chung A, Bonney GK, Goh BKP, Fu N, Yu VC, Zhai W, Albani S, Chow PKH, and Chew V
- Subjects
- Animals, CD8-Positive T-Lymphocytes, Humans, Immune Evasion, Mice, Transcriptome, Carcinoma, Hepatocellular pathology, Liver Neoplasms pathology
- Abstract
Immune evasion is key to cancer initiation and later at metastasis, but its dynamics at intermediate stages, where potential therapeutic interventions could be applied, is undefined. Here we show, using multi-dimensional analyses of resected tumours, their adjacent non-tumour tissues and peripheral blood, that extensive immune remodelling takes place in patients with stage I to III hepatocellular carcinoma (HCC). We demonstrate the depletion of anti-tumoural immune subsets and accumulation of immunosuppressive or exhausted subsets along with reduced tumour infiltration of CD8 T cells peaking at stage II tumours. Corresponding transcriptomic modification occur in the genes related to antigen presentation, immune responses, and chemotaxis. The progressive immune evasion is validated in a murine model of HCC. Our results show evidence of ongoing tumour-immune co-evolution during HCC progression and offer insights into potential interventions to reverse, prevent or limit the progression of the disease., (© 2022. The Author(s).)
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- 2022
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13. A Rare Case of Duodenal Papilla Metastasis From the Gastroesophageal Junction.
- Author
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Chua WJ, Wan WK, and Yew Tan DM
- Subjects
- Adenocarcinoma diagnosis, Adult, Biopsy, Cholangiopancreatography, Endoscopic Retrograde methods, Diagnosis, Differential, Duodenal Neoplasms diagnosis, Endoscopy, Digestive System methods, Esophageal Neoplasms diagnosis, Esophageal Neoplasms secondary, Female, Humans, Neoplasm Metastasis, Adenocarcinoma secondary, Ampulla of Vater pathology, Duodenal Neoplasms secondary, Esophageal Neoplasms pathology, Esophagogastric Junction pathology, Rare Diseases
- Published
- 2022
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14. Dynamic phenotypic heterogeneity and the evolution of multiple RNA subtypes in hepatocellular carcinoma: the PLANET study.
- Author
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Zhai W, Lai H, Kaya NA, Chen J, Yang H, Lu B, Lim JQ, Ma S, Chew SC, Chua KP, Alvarez JJS, Chen PJ, Chang MM, Wu L, Goh BKP, Chung AY, Chan CY, Cheow PC, Lee SY, Kam JH, Kow AW, Ganpathi IS, Chanwat R, Thammasiri J, Yoong BK, Ong DB, de Villa VH, Dela Cruz RD, Loh TJ, Wan WK, Zeng Z, Skanderup AJ, Pang YH, Madhavan K, Lim TK, Bonney G, Leow WQ, Chew V, Dan YY, Tam WL, Toh HC, Foo RS, and Chow PK
- Abstract
Intra-tumor heterogeneity (ITH) is a key challenge in cancer treatment, but previous studies have focused mainly on the genomic alterations without exploring phenotypic (transcriptomic and immune) heterogeneity. Using one of the largest prospective surgical cohorts for hepatocellular carcinoma (HCC) with multi-region sampling, we sequenced whole genomes and paired transcriptomes from 67 HCC patients (331 samples). We found that while genomic ITH was rather constant across stages, phenotypic ITH had a very different trajectory and quickly diversified in stage II patients. Most strikingly, 30% of patients were found to contain more than one transcriptomic subtype within a single tumor. Such phenotypic ITH was found to be much more informative in predicting patient survival than genomic ITH and explains the poor efficacy of single-target systemic therapies in HCC. Taken together, we not only revealed an unprecedentedly dynamic landscape of phenotypic heterogeneity in HCC, but also highlighted the importance of studying phenotypic evolution across cancer types., (© The Author(s) 2021. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)
- Published
- 2021
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15. CD30 + OX40 + Treg is associated with improved overall survival in colorectal cancer.
- Author
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Lam JH, Hong M, Koo SL, Chua CWL, Lim KL, Wee F, Wan WK, Leow WQ, Yeo JG, Tan IBH, Yeong J, Lim TKH, and Lim TS
- Subjects
- Biomarkers, Tumor immunology, Cells, Cultured, Humans, Leukocyte Common Antigens immunology, Prospective Studies, Receptors, Cytokine immunology, Retrospective Studies, Colorectal Neoplasms immunology, Colorectal Neoplasms mortality, Ki-1 Antigen immunology, Receptors, OX40 immunology, T-Lymphocytes, Regulatory immunology
- Abstract
Regulatory T cells (Tregs) are often enriched in tumors, where their immunosuppressive function has a key role in tumor persistence and progression. In colorectal cancer (CRC), however, Tregs are frequently associated with an improved clinical outcome. Tumor-infiltrating Tregs have been shown to exhibit a distinct signature comprising the co-stimulatory molecules (OX40, 4-1BB), cytokine receptors (IL1R2, IL21R, CCR8, CD30), and co-inhibitory molecules (PD-L1, TIGIT). Here, we showed by flow cytometry that circulating CD45RO
+ Tregs from patients with CRC (n = 25) have elevated CD30 and OX40 expression compared to healthy subjects (n = 14). We identified co-expression of CD30 and OX40 on circulating CD45RO+ Tregs using single-cell images captured by the DEPArray™ system. The frequency of CD30+ OX40+ CD45RO+ Tregs was significantly higher in CRC patients than in healthy subjects (P < 0.001). Importantly, receiver operating characteristic analysis confirmed that this CD30+ OX40+ Treg subset could strongly discriminate between CRC patients and healthy subjects with the highest accuracy of 92.3%, an AUC of 0.92, a sensitivity of 88%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 82.35%, and a trade-off value of 3.44%, compared to other Treg subsets. Consistently, multiplex-IHC/IF of tumor-infiltrating Tregs revealed a significant association between high densities of CD30+ OX40+ Tregs and improved overall survival; no such association was found for other subsets. These data suggest a potential role for CD30+ OX40+ Tregs as a diagnostic or prognostic biomarker in CRC., (© 2021. The Author(s).)- Published
- 2021
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16. Author Correction: Intratumoural immune heterogeneity as a hallmark of tumour evolution and progression in hepatocellular carcinoma.
- Author
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Nguyen PHD, Ma S, Phua CZJ, Kaya NA, Lai HLH, Lim CJ, Lim JQ, Wasser M, Lai L, Tam WL, Lim TKH, Wan WK, Loh T, Leow WQ, Pang YH, Chan CY, Lee SY, Cheow PC, Toh HC, Ginhoux F, Iyer S, Kow AWC, Young Dan Y, Chung A, Bonney GK, Goh BKP, Albani S, Chow PKH, Zhai W, and Chew V
- Published
- 2021
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17. Intratumoural immune heterogeneity as a hallmark of tumour evolution and progression in hepatocellular carcinoma.
- Author
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Nguyen PHD, Ma S, Phua CZJ, Kaya NA, Lai HLH, Lim CJ, Lim JQ, Wasser M, Lai L, Tam WL, Lim TKH, Wan WK, Loh T, Leow WQ, Pang YH, Chan CY, Lee SY, Cheow PC, Toh HC, Ginhoux F, Iyer S, Kow AWC, Young Dan Y, Chung A, Bonney GK, Goh BKP, Albani S, Chow PKH, Zhai W, and Chew V
- Subjects
- DNA genetics, Gene Editing, Gene Regulatory Networks, Humans, Leukocytes, Mononuclear metabolism, Phylogeny, Prognosis, RNA genetics, Survival Analysis, Transcriptome genetics, Treatment Outcome, Tumor Microenvironment immunology, Carcinoma, Hepatocellular immunology, Carcinoma, Hepatocellular pathology, Disease Progression, Liver Neoplasms immunology, Liver Neoplasms pathology
- Abstract
The clinical relevance of immune landscape intratumoural heterogeneity (immune-ITH) and its role in tumour evolution remain largely unexplored. Here, we uncover significant spatial and phenotypic immune-ITH from multiple tumour sectors and decipher its relationship with tumour evolution and disease progression in hepatocellular carcinomas (HCC). Immune-ITH is associated with tumour transcriptomic-ITH, mutational burden and distinct immune microenvironments. Tumours with low immune-ITH experience higher immunoselective pressure and escape via loss of heterozygosity in human leukocyte antigens and immunoediting. Instead, the tumours with high immune-ITH evolve to a more immunosuppressive/exhausted microenvironment. This gradient of immune pressure along with immune-ITH represents a hallmark of tumour evolution, which is closely linked to the transcriptome-immune networks contributing to disease progression and immune inactivation. Remarkably, high immune-ITH and its transcriptomic signature are predictive for worse clinical outcome in HCC patients. This in-depth investigation of ITH provides evidence on tumour-immune co-evolution along HCC progression.
- Published
- 2021
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18. Clinical profile of non-alcoholic fatty liver disease in nonobese patients.
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Lum JHM, Cheah MCC, Leow WQ, Wan WK, Lim TKH, Chow WC, Chang JPE, and Goh GBB
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- Adult, Aged, Asian People, Aspartate Aminotransferases blood, Biomarkers blood, Body Mass Index, Cohort Studies, Female, Humans, Liver Cirrhosis diagnosis, Liver Cirrhosis etiology, Liver Cirrhosis pathology, Male, Metabolic Syndrome complications, Middle Aged, Organ Dysfunction Scores, Platelet Count, Risk, Non-alcoholic Fatty Liver Disease etiology, Obesity
- Abstract
Background and Aim: Non-alcoholic fatty liver disease (NAFLD) is associated with metabolic syndrome. Worryingly, it has been increasingly reported among nonobese patients. This study aims to analyse patient characteristics of biopsy-proven NAFLD in an Asian cohort and explore differences stratified by body mass index (BMI)., Methods: Clinical, laboratory, and histological data were collected from 263 adults with biopsy-proven NAFLD. Patients with and without obesity (BMI cut-off 25) were compared. The ability to predict advanced liver fibrosis with three non-invasive scores, the NAFLD Fibrosis score (NFS), Fibrosis-4 (FIB4), and the aspartate aminotransferase to platelet ratio index (APRI), was compared., Results: Obese subjects had a lower mean age (49.5 ± 12.5 vs 54.0 ± 12.9 years, P = 0.017), a higher prevalence of diabetes (52.4% vs 36.8%, P = 0.037), and a higher waist circumference (113.9 ± 16.0 cm vs 87.0 ± 18.4 cm, P = 0.022). The prevalence of dyslipidaemia (68.0% vs 61.4%, P = 0.353) and hypertension (61.7% vs 49.1%, P = 0.190) was comparable between the two groups. The distribution of non-alcoholic steatohepatitis (NASH) (63.1% versus 61.4%, P = 0.710) and advanced fibrosis (31.6% versus 26.3%, P = 0.447) were also similar in both groups. All three non-invasive scores (NFS, FIB4, and APRI) performed poorly in predicting advanced fibrosis in nonobese patients with NAFLD. The FIB4 was the most accurate non-invasive score in predicting advanced fibrosis in the obese group., Conclusions: Obese and nonobese patients are equally at risk of NASH and advanced fibrosis. While the FIB4 is the most accurate non-invasive score in predicting advanced fibrosis among obese individuals, further research is warranted to develop a nonobese specific score to correctly identify nonobese NAFLD patients with advanced fibrosis., (© 2020 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)
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- 2021
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19. Unusual cause of arterial enhancing liver tumour.
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Chong C, Wan WK, and Goh BKP
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- Arteries, Humans, Liver diagnostic imaging, Carcinoma, Hepatocellular, Liver Neoplasms diagnostic imaging
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- 2020
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20. An Improved qFibrosis Algorithm for Precise Screening and Enrollment into Non-Alcoholic Steatohepatitis (NASH) Clinical Trials.
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Leow WQ, Bedossa P, Liu F, Wei L, Lim KH, Wan WK, Ren Y, Chang JP, Tan CK, Wee A, and Goh GB
- Abstract
Background: Many clinical trials with potential drug treatment options for non-alcoholic fatty liver disease (NAFLD) are focused on patients with non-alcoholic steatohepatitis (NASH) stages 2 and 3 fibrosis. As the histological features differentiating stage 1 (F1) from stage 2 (F2) NASH fibrosis are subtle, some patients may be wrongly staged by the in-house pathologist and miss the opportunity for enrollment into clinical trials. We hypothesized that our refined artificial intelligence (AI)-based algorithm (qFibrosis) can identify these subtle differences and serve as an assistive tool for in-house pathologists., Methods: Liver tissue from 160 adult patients with biopsy-proven NASH from Singapore General Hospital (SGH) and Peking University People's Hospital (PKUH) were used. A consensus read by two expert hepatopathologists was organized. The refined qFibrosis algorithm incorporated the creation of a periportal region that allowed for the increased detection of periportal fibrosis. Consequently, an additional 28 periportal parameters were added, and 28 pre-existing perisinusoidal parameters had altered definitions., Results: Twenty-eight parameters (20 periportal and 8 perisinusoidal) were significantly different between the F1 and F2 cases that prompted a change of stage after a careful consensus read. The discriminatory ability of these parameters was further demonstrated in a comparison between the true F1 and true F2 cases as 26 out of the 28 parameters showed significant differences. These 26 parameters constitute a novel sub-algorithm that could accurately stratify F1 and F2 cases., Conclusion: The refined qFibrosis algorithm incorporated 26 novel parameters that showed a good discriminatory ability for NASH fibrosis stage 1 and 2 cases, representing an invaluable assistive tool for in-house pathologists when screening patients for NASH clinical trials.
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- 2020
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21. qFIBS: An Automated Technique for Quantitative Evaluation of Fibrosis, Inflammation, Ballooning, and Steatosis in Patients With Nonalcoholic Steatohepatitis.
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Liu F, Goh GB, Tiniakos D, Wee A, Leow WQ, Zhao JM, Rao HY, Wang XX, Wang Q, Wan WK, Lim KH, Romero-Gomez M, Petta S, Bugianesi E, Tan CK, Harrison SA, Anstee QM, Chang PJ, and Wei L
- Subjects
- Algorithms, Asian People, Dimensional Measurement Accuracy, Female, Humans, Male, Middle Aged, Reference Standards, Reproducibility of Results, Severity of Illness Index, White People, Biopsy methods, Biopsy standards, Fatty Liver diagnostic imaging, Fatty Liver etiology, Hepatitis diagnostic imaging, Hepatitis etiology, Image Interpretation, Computer-Assisted methods, Liver diagnostic imaging, Liver pathology, Liver Cirrhosis diagnostic imaging, Liver Cirrhosis etiology, Non-alcoholic Fatty Liver Disease pathology
- Abstract
Background and Aims: Nonalcoholic steatohepatitis (NASH) is a common cause of chronic liver disease. Clinical trials use the NASH Clinical Research Network (CRN) system for semiquantitative histological assessment of disease severity. Interobserver variability may hamper histological assessment, and diagnostic consensus is not always achieved. We evaluate a second harmonic generation/two-photon excitation fluorescence (SHG/TPEF) imaging-based tool to provide an automated quantitative assessment of histological features pertinent to NASH., Approach and Results: Images were acquired by SHG/TPEF from 219 nonalcoholic fatty liver disease (NAFLD)/NASH liver biopsy samples from seven centers in Asia and Europe. These were used to develop and validate qFIBS, a computational algorithm that quantifies key histological features of NASH. qFIBS was developed based on in silico analysis of selected signature parameters for four cardinal histopathological features, that is, fibrosis (qFibrosis), inflammation (qInflammation), hepatocyte ballooning (qBallooning), and steatosis (qSteatosis), treating each as a continuous rather than categorical variable. Automated qFIBS analysis outputs showed strong correlation with each respective component of the NASH CRN scoring (P < 0.001; qFibrosis [r = 0.776], qInflammation [r = 0.557], qBallooning [r = 0.533], and qSteatosis [r = 0.802]) and high area under the receiver operating characteristic curve values (qFibrosis [0.870-0.951; 95% confidence interval {CI}, 0.787-1.000; P < 0.001], qInflammation [0.820-0.838; 95% CI, 0.726-0.933; P < 0.001), qBallooning [0.813-0.844; 95% CI, 0.708-0.957; P < 0.001], and qSteatosis [0.939-0.986; 95% CI, 0.867-1.000; P < 0.001]) and was able to distinguish differing grades/stages of histological disease. Performance of qFIBS was best when assessing degree of steatosis and fibrosis, but performed less well when distinguishing severe inflammation and higher ballooning grades., Conclusions: qFIBS is an automated tool that accurately quantifies the critical components of NASH histological assessment. It offers a tool that could potentially aid reproducibility and standardization of liver biopsy assessments required for NASH therapeutic clinical trials., (© 2019 by the American Association for the Study of Liver Diseases.)
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- 2020
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22. Low-Cost Method and Biochip for Measuring the Trans-Epithelial Electrical Resistance (TEER) of Esophageal Epithelium.
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Poenar DP, Yang G, Wan WK, and Feng S
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Trans-epithelial electrical resistance (TEER) is a good indicator of the barrier integrity of epithelial tissues and is often employed in biomedical research as an effective tool to assess ion transport and permeability of tight junctions. The Ussing chamber is the gold standard for measuring TEER of tissue specimens, but it has major drawbacks: it is a macroscopic method that requires a careful and labor intensive sample mounting protocol, allows a very limited viability for the mounted sample, has large parasitic components and low throughput as it cannot perform multiple simultaneous measurements, and this sophisticated and delicate apparatus has a relatively high cost. This paper demonstrates a low-cost home-made "sandwich ring" method which was used to measure the TEER of tissue specimens effectively. This method inspired the subsequent design of a biochip fabricated using standard soft lithography and laser engraving technologies, with which the TEER of pig epithelial tissues was measured. Moreover, it was possible to temporarily preserve the tissue specimens for days in the biochip and monitor the TEER continuously. Tissue responses after exposure tests to media of various pH values were also successfully recorded using the biochip. All these demonstrate that this biochip could be an effective, cheaper, and easier to use Ussing chamber substitute that may have relevant applications in clinical practice.
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- 2020
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23. Presence of Hepatic Steatosis Does Not Increase the Risk of Hepatocellular Carcinoma in Patients With Chronic Hepatitis B Over Long Follow-Up.
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Lim CT, Goh GBB, Li H, Lim TK, Leow WQ, Wan WK, Azhar R, Chow WC, and Kumar R
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Background: Chronic hepatitis B (CHB) infection and nonalcoholic fatty liver disease (NAFLD) are liver diseases which may lead to hepatocellular carcinoma (HCC) formation. Both disease entities have been attributed independently to increase risk of HCC development. While concomitant hepatic steatosis in patients with CHB are becoming more frequent in view of increasing NAFLD prevalence, there is no conclusive evidence linking presence of hepatic steatosis and increased HCC risk in patients with CHB infection. This study explores the association of hepatic steatosis among CHB-infected individuals in HCC development., Methods: This is a retrospective study on a cohort of patients with CHB who underwent liver biopsy between January 2000 and December 2014. They were stratified according to presence and severity of histologically proven hepatic steatosis and subsequently followed up to evaluate the association between hepatic steatosis and HCC development., Results: Among 289 patients with a median follow-up of 111.1 months, hepatic steatosis was present in 185 patients (64.0%). In all, 27 patients developed HCC on follow-up and 21 of them had hepatic steatosis. Univariate Cox analysis showed that age (hazard ratio [HR] = 1.08, 95% CI = 1.042-1.12), type 2 diabetes mellitus (T2DM) (HR = 4.00, 95% CI = 1.622-9.863), and Ishak score (HR = 1.221, 95% CI = 1.014-1.472) were associated with HCC development, whereas multivariate Cox analysis demonstrated that age and T2DM (HR = 2.69, 95% CI = 1.072-6.759) were significant risk factors for development of HCC., Conclusions: Concurrent hepatic steatosis in patients with CHB infection is not a risk factor for hepatocellular carcinoma formation., Competing Interests: Declaration of conflicting interests:The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)
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- 2020
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24. Case Report of a Mediastinal Vascular Malformation Mimicking Esophageal Varices on Endoscopy, with Emphasis on Radiological Findings.
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Wang M, Wan WK, and Francis J
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- Diagnosis, Differential, Endoscopy, Humans, Male, Middle Aged, Mediastinum diagnostic imaging, Vascular Malformations diagnostic imaging
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BACKGROUND Mediastinal vascular malformations are rare, and most patients are asymptomatic or present with unrelated symptoms. Imaging can be challenging to interpret, but plays an important role in diagnosis and prognostication. CASE REPORT We present the case of a 48-year-old man with history of intravenous drug abuse and incompletely treated pulmonary tuberculosis. A computed tomography (CT) scan done for respiratory symptoms showed an extensive soft-tissue mass in the mediastinum and upper abdomen, initially thought to represent tuberculous adenitis with possible esophageal involvement, which appeared variceal in nature on endoscopy. Further investigation with open mediastinal biopsy and magnetic resonance imaging (MRI) eventually led to the diagnosis of a low-flow venous mediastinal vascular malformation. The patient responded well to conservative management, with the malformation remaining stable on follow-up CT up to a decade later. CONCLUSIONS Radiologists should be aware of the rare but important differential diagnosis of a vascular malformation, particularly when an extensive infiltrative calcified mediastinal soft-tissue mass is encountered. Multi-modality imaging, particularly MRI, which can demonstrate typical features, is crucial for diagnosis and prognostication, thereby avoiding unnecessary invasive procedures and treatment.
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- 2020
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25. Hepatic angiomyolipoma presenting as an arterially enhancing liver lesion.
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Khoo CY, Wan WK, and Goh BKP
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- Angiomyolipoma diagnosis, Arteries, Female, Humans, Liver Neoplasms diagnosis, Middle Aged, Angiomyolipoma blood supply, Liver Neoplasms blood supply
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- 2019
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26. Quantification of hepatic steatosis in chronic liver disease using novel automated method of second harmonic generation and two-photon excited fluorescence.
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Goh GB, Leow WQ, Liang S, Wan WK, Lim TKH, Tan CK, and Chang PE
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- Algorithms, Automation, Laboratory methods, Fatty Liver diagnosis, Fluorescence, Humans, Liver pathology, Liver Cirrhosis pathology, Liver Diseases pathology, Photons, Reproducibility of Results, Fatty Liver metabolism, Fatty Liver pathology, Microscopy, Fluorescence, Multiphoton methods, Second Harmonic Generation Microscopy methods
- Abstract
The presence of hepatic steatosis (HS) is an important histological feature in a variety of liver disease. It is critical to assess HS accurately, particularly where it plays an integral part in defining the disease. Conventional methods of quantifying HS remain semi-quantitative, with potential limitations in precision, accuracy and subjectivity. Second Harmonic Generation (SHG) microscopy is a novel technology using multiphoton imaging techniques with applicability in histological tissue assessment. Using an automated algorithm based on signature SHG parameters, we explored the utility and application of SHG for the diagnosis and quantification of HS. SHG microscopy analysis using GENESIS (HistoIndex, Singapore) was applied on 86 archived liver biopsy samples. Reliability was correlated with 3 liver histopathologists. Data analysis was performed using SPSS. There was minimal inter-observer variability between the 3 liver histopathologists, with an intraclass correlation of 0.92 (95% CI 0.89-0.95; p < 0.001). Good correlation was observed between the histopathologists and automated SHG microscopy assessment of HS with Pearson correlation of 0.93: p < 0.001. SHG microscopy provides a valuable tool for objective, more precise measure of HS using an automated approach. Our study reflects proof of concept evidence for potential future refinement to current conventional histological assessment.
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- 2019
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27. An integrated automated multispectral imaging technique that simultaneously detects and quantitates viral RNA and immune cell protein markers in fixed sections from Epstein-Barr virus-related tumours.
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Wee YTF, Alkaff SMF, Lim JCT, Loh JJH, Hilmy MH, Ong C, Nei WL, Jain A, Lim A, Takano A, Azhar R, Wan WK, Newell E, Yeong J, and Lim TKH
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- Carcinoma immunology, Carcinoma virology, Epstein-Barr Virus Infections complications, Herpesvirus 4, Human, Hodgkin Disease immunology, Hodgkin Disease virology, Humans, Biomarkers, Tumor analysis, Fluorescent Antibody Technique methods, Immunophenotyping methods, In Situ Hybridization methods, RNA, Viral analysis
- Abstract
Background/aim: Epstein-Barr virus (EBV) is an oncovirus that is commonly associated with the development of lymphomas and epithelial carcinomas. In the era of immunotherapy, histological evaluation of EBV-related cancers is currently a multi-sample, multi-technique process requiring separate time-consuming detection of EBV-encoded small RNAs by in situ hybridisation (ISH), and parallel labelling of sections for cancer-associated protein markers., Methods: Using EBV-associated tumours as proof-of-concept for feasibility, here we developed an approach that allows simultaneous detection of EBV RNAs and multiple protein markers such as PD-L1, EBV-LMP, CD8, CD4, CD20, CD30 and CD15on a single tissue section based on our recently reported automated staining protocol., Results: We successfully combined multiplex immunofluorescence (mIF) to detect 3 abovementioned protein markers involved in cancer, with ISH, and applied the protocol to f tissue samples from patients diagnosed with EBV-associated pulmonary lymphoepithelioma-like carcinoma (LELC), gastric carcinoma and Hodgkin's Lymphoma. Empowered by the Vectra 3 Automated Quantitative Pathology Imaging System, we demonstrate the utility and potential of this integrated approach to concurrently detect and quantitate viral RNA and protein biomarkers of immune and tumour cells., Conclusion: This study represents an important step forward in the research and diagnosis of EBV-associated cancers, and could be readily modified to include other proteins and RNA markers to apply to other malignancies. More importantly, the novel automated ISH-mIF protocol that we detailly described here could also be readily reproduced by most of the diagnostic and research lab to future projects that aim to look at both RNA and protein markers., (Copyright © 2018 Elsevier Inc. All rights reserved.)
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- 2018
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28. An Unusual Cause of a Solid-Cystic Pancreatic Lesion.
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Goh BKP, Kwek ABE, and Wan WK
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- Choristoma diagnosis, Endoscopic Ultrasound-Guided Fine Needle Aspiration, Epidermal Cyst diagnosis, Epidermal Cyst surgery, Female, Humans, Magnetic Resonance Imaging, Middle Aged, Pancreatectomy, Pancreatic Cyst diagnosis, Pancreatic Cyst surgery, Tomography, X-Ray Computed, Choristoma complications, Epidermal Cyst complications, Pancreatic Cyst complications, Spleen
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- 2018
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29. GRAM domain-containing protein 1B (GRAMD1B), a novel component of the JAK/STAT signaling pathway, functions in gastric carcinogenesis.
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Khanna P, Chua PJ, Wong BSE, Yin C, Thike AA, Wan WK, Tan PH, and Baeg GH
- Abstract
Dysregulated JAK/STAT signaling has been implicated in the molecular pathogenesis of gastric cancer. However, downstream effectors of STAT signaling that facilitate gastric carcinogenesis remain to be explored. We previously identified the Drosophila ortholog of human GRAMD1B in our genome-wide RNAi screen to identify novel components of the JAK/STAT signaling pathway in Drosophila . Here, we examined the involvement of GRAMD1B in JAK/STAT-associated gastric carcinogenesis. We found that GRAMD1B expression is positively regulated by JAK/STAT signaling and GRAMD1B inhibition decreases STAT3 levels, suggesting the existence of a positive feedback loop. Consistently, GRAMD1B and JAK/STAT signaling acted synergistically to promote gastric cancer cell survival by upregulating the expression of the anti-apoptotic molecule Bcl-xL. Interestingly, our immunohistochemical analysis for GRAMD1B revealed a gradual loss of cytoplasmic staining but an increase in the nuclear accumulation of GRAMD1B, as gastric tissue becomes malignant. GRAMD1B expression levels were also found to be significantly associated with clinicopathological features of the gastric cancer patients, particularly the tumor grades and lymph node status. Moreover, GRAMD1B and pSTAT3 (Tyr705) showed a positive correlation in gastric tissues, thereby confirming the existence of a close link between these two signaling molecules in vivo . This new knowledge about JAK/STAT-GRAMD1B regulation deepens our understanding of JAK/STAT signaling in gastric carcinogenesis and provides a foundation for the development of novel biomarkers in gastric cancer., Competing Interests: CONFLICTS OF INTEREST Authors declare no conflicts of interest.
- Published
- 2017
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30. Esophageal Metastatic Adenocarcinoma Diagnosed with Endoscopic Ultrasound.
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Teh GXJ, Tan D, Khor JL, Wan WK, and Wang YT
- Abstract
Metastasis to the esophagus from a distant primary cancer is a rare manifestation in a patient with a history of oncological disease presenting with obstructive upper gastrointestinal symptoms. Computed tomography of the thorax or esophagogastroduodenoscopy can be non-diagnostic as the disease tends to be submucosal. In such a situation, endoscopic ultrasound (EUS) with fine needle aspiration (FNA) can be directed to characterize and sample the submucosal esophageal lesion. We present a case series of metastatic esophageal strictures diagnosed with EUS and FNA.
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- 2017
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31. Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors.
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Nastase A, Teo JY, Heng HL, Ng CC, Myint SS, Rajasegaran V, Loh JL, Lee SY, Ooi LL, Chung AY, Chow PK, Cheow PC, Wan WK, Azhar R, Khoo A, Xiu SX, Alkaff SM, Cutcutache I, Lim JQ, Ong CK, Herlea V, Dima S, Duda DG, Teh BT, Popescu I, and Lim TK
- Abstract
AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A . In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A . Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.
- Published
- 2017
32. A case report of wound site seeding following cholecystectomy for dysplastic gallbladder.
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Ng YA, Tan QT, Wan WK, and Goh YC
- Abstract
Wound site metastasis following cholecystectomy is an uncommon but well recognised complication following laparoscopic surgery for unsuspected gallbladder carcinoma. We describe a case of implantation of dysplastic cells with subsequent malignant transformation at the incision site 3 years post-cholecystectomy for an inflamed gallbladder. Histopathological examination of this tumour confirmed adenocarcinoma of pancreatobiliary origin, possibly secondary to gallbladder cells implantation and subsequent carcinomatous change. Unlike previously reported cases, the present case has two unique features: Firstly, the histology of the resected gallbladder at the initial operation was that of a low-grade dysplasia and not carcinoma; and secondly, there was a long interval between initial surgery and subsequent development of the wound site tumour. This case highlights that careful handling of the specimen tissue intraoperatively is paramount as cells implanted in the wound site can survive and undergo malignant transformation. All new masses occurring along the surgical wound site should be followed up and investigated to exclude implanted tumours., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2017
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33. Mechanoregulation of cardiac myofibroblast differentiation: implications for cardiac fibrosis and therapy.
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Yong KW, Li Y, Huang G, Lu TJ, Safwani WK, Pingguan-Murphy B, and Xu F
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- Animals, Extracellular Matrix metabolism, Fibrosis metabolism, Fibrosis therapy, Humans, Myocardium cytology, Myocardium pathology, Myofibroblasts metabolism, Myofibroblasts physiology, Tissue Engineering, Cell Differentiation, Myocardium metabolism, Myofibroblasts cytology, Stress, Mechanical
- Abstract
Cardiac myofibroblast differentiation, as one of the most important cellular responses to heart injury, plays a critical role in cardiac remodeling and failure. While biochemical cues for this have been extensively investigated, the role of mechanical cues, e.g., extracellular matrix stiffness and mechanical strain, has also been found to mediate cardiac myofibroblast differentiation. Cardiac fibroblasts in vivo are typically subjected to a specific spatiotemporally changed mechanical microenvironment. When exposed to abnormal mechanical conditions (e.g., increased extracellular matrix stiffness or strain), cardiac fibroblasts can undergo myofibroblast differentiation. To date, the impact of mechanical cues on cardiac myofibroblast differentiation has been studied both in vitro and in vivo. Most of the related in vitro research into this has been mainly undertaken in two-dimensional cell culture systems, although a few three-dimensional studies that exist revealed an important role of dimensionality. However, despite remarkable advances, the comprehensive mechanisms for mechanoregulation of cardiac myofibroblast differentiation remain elusive. In this review, we introduce important parameters for evaluating cardiac myofibroblast differentiation and then discuss the development of both in vitro (two and three dimensional) and in vivo studies on mechanoregulation of cardiac myofibroblast differentiation. An understanding of the development of cardiac myofibroblast differentiation in response to changing mechanical microenvironment will underlie potential targets for future therapy of cardiac fibrosis and failure., (Copyright © 2015 the American Physiological Society.)
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- 2015
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34. Eosinophilic gastroenteritis: Clinical profiles and treatment outcomes, a retrospective study of 18 adult patients in a Singapore Tertiary Hospital.
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Wong GW, Lim KH, Wan WK, Low SC, and Kong SC
- Abstract
Background: Eosinophilic gastroenteritis (EG) can mimic symptoms of common gastrointestinal (GI) disorders but responds well to appropriate treatment. Accurate diagnosis is central to effective management. Data on EG in Southeast Asia is lacking. We aim to describe the clinical profiles and treatment outcomes of adult patients with EG in a Singapore Tertiary Hospital., Materials and Methods: This retrospective study involved archival search of patients with GI biopsies that showed eosinophilic infiltration from January 2004 to December 2012. Patients' clinical data from computerised hospital records and clinical notes was reviewed. Diagnostic criteria for EG included presence of GI symptoms with more than 30 eosinophils/high power field on GI biopsies. Patients with secondary causes for eosinophilia were excluded., Results: Eighteen patients with EG were identified (mean age 52 years; male/female: 11/7). Fifteen patients (83%) had peripheral blood eosinophilia. Seven patients (39%) had atopic conditions. Most common symptoms were diarrhoea and abdominal pain. Small intestine was the most common site involved. Endoscopic finding was non-specific. Ten patients were treated with corticosteroids (nine prednisolone, one budesonide): eight patients (89%) responded clinically to prednisolone but four patients (50%) relapsed following tapering-off of prednisolone and required maintenance dose. One patient each responded to diet elimination and montelukast respectively. Half of the remaining six patients who were treated with proton-pump inhibitors, antispasmodic or antidiarrheal agents still remained symptomatic., Conclusion: Prednisolone is an effective treatment though relapses are common. Small intestine is most commonly involved. EG should be considered in the evaluation of unexplained chronic recurrent GI symptoms.
- Published
- 2015
35. Regulatory crosstalk between lineage-survival oncogenes KLF5, GATA4 and GATA6 cooperatively promotes gastric cancer development.
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Chia NY, Deng N, Das K, Huang D, Hu L, Zhu Y, Lim KH, Lee MH, Wu J, Sam XX, Tan GS, Wan WK, Yu W, Gan A, Tan AL, Tay ST, Soo KC, Wong WK, Dominguez LT, Ng HH, Rozen S, Goh LK, Teh BT, and Tan P
- Subjects
- Animals, Cell Proliferation, Cell Transformation, Neoplastic genetics, Cell Transformation, Neoplastic metabolism, GATA4 Transcription Factor biosynthesis, GATA6 Transcription Factor biosynthesis, Gene Expression Profiling methods, Gene Silencing, Genetic Predisposition to Disease, Heterografts, Humans, Kruppel-Like Transcription Factors biosynthesis, Mice, Nude, Neoplasm Transplantation, Oncogenes genetics, Promoter Regions, Genetic, Stomach Neoplasms metabolism, Stomach Neoplasms pathology, Tumor Cells, Cultured, GATA4 Transcription Factor genetics, GATA6 Transcription Factor genetics, Gene Expression Regulation, Neoplastic genetics, Kruppel-Like Transcription Factors genetics, Stomach Neoplasms genetics
- Abstract
Objective: Gastric cancer (GC) is a deadly malignancy for which new therapeutic strategies are needed. Three transcription factors, KLF5, GATA4 and GATA6, have been previously reported to exhibit genomic amplification in GC. We sought to validate these findings, investigate how these factors function to promote GC, and identify potential treatment strategies for GCs harbouring these amplifications., Design: KLF5, GATA4 and GATA6 copy number and gene expression was examined in multiple GC cohorts. Chromatin immunoprecipitation with DNA sequencing was used to identify KLF5/GATA4/GATA6 genomic binding sites in GC cell lines, and integrated with transcriptomics to highlight direct target genes. Phenotypical assays were conducted to assess the function of these factors in GC cell lines and xenografts in nude mice., Results: KLF5, GATA4 and GATA6 amplifications were confirmed in independent GC cohorts. Although factor amplifications occurred in distinct sets of GCs, they exhibited significant mRNA coexpression in primary GCs, consistent with KLF5/GATA4/GATA6 cross-regulation. Chromatin immunoprecipitation with DNA sequencing revealed a large number of genomic sites co-occupied by KLF5 and GATA4/GATA6, primarily located at gene promoters and exhibiting higher binding strengths. KLF5 physically interacted with GATA factors, supporting KLF5/GATA4/GATA6 cooperative regulation on co-occupied genes. Depletion and overexpression of these factors, singly or in combination, reduced and promoted cancer proliferation, respectively, in vitro and in vivo. Among the KLF5/GATA4/GATA6 direct target genes relevant for cancer development, one target gene, HNF4α, was also required for GC proliferation and could be targeted by the antidiabetic drug metformin, revealing a therapeutic opportunity for KLF5/GATA4/GATA6 amplified GCs., Conclusions: KLF5/GATA4/GATA6 may promote GC development by engaging in mutual crosstalk, collaborating to maintain a pro-oncogenic transcriptional regulatory network in GC cells., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)
- Published
- 2015
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36. An integrative approach identified genes associated with drug response in gastric cancer.
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Zhou J, Yong WP, Yap CS, Vijayaraghavan A, Sinha RA, Singh BK, Xiu S, Manesh S, Ngo A, Lim A, Ang C, Xie C, Wong FY, Lin SJ, Wan WK, Tan IB, Flotow H, Tan P, Lim KH, Yen PM, and Goh LK
- Subjects
- Apoptosis drug effects, Apoptosis genetics, Calcium-Binding Proteins, Cell Line, Tumor, Cell Proliferation drug effects, Cell Proliferation genetics, Cisplatin pharmacology, Cytoskeletal Proteins genetics, DEAD-box RNA Helicases biosynthesis, DNA Copy Number Variations genetics, DNA Damage drug effects, DNA Damage genetics, DNA Methylation genetics, Databases, Nucleic Acid, Epirubicin pharmacology, Gastric Mucosa cytology, Gene Expression Profiling, Gene Expression Regulation, Neoplastic, Histones genetics, Humans, Nerve Tissue Proteins genetics, Prognosis, RNA Interference, RNA, Small Interfering, Retrospective Studies, Transcription Factors genetics, Antineoplastic Agents pharmacology, DEAD-box RNA Helicases genetics, Drug Resistance, Neoplasm genetics, Stomach Neoplasms drug therapy, Stomach Neoplasms genetics
- Abstract
Gastric cancer (GC) is the second leading cause of global cancer mortality worldwide. However, the molecular mechanism underlying its carcinogenesis and drug resistance is not well understood. To identify novel functionally important genes that were differentially expressed due to combinations of genetic and epigenetic changes, we analyzed datasets containing genome-wide mRNA expression, DNA copy number alterations and DNA methylation status from 154 primary GC samples and 47 matched non-neoplastic mucosa tissues from Asian patients. We used concepts of 'within' and 'between' statistical analysis to compare the difference between tumors and controls within each platform, and assessed the correlations between platforms. This 'multi-regulated gene (MRG)' analysis identified 126 differentially expressed genes that underwent a combination of copy number and DNA methylation changes. Most genes were located at genomic loci associated with GC. Statistical enrichment analysis showed that MRGs were enriched for cancer, GC and drug response. We analysed several MRGs that previously had not been associated with GC. Knockdown of DDX27, TH1L or IDH3G sensitized cells to epirubicin or cisplatin, and knockdown of RAI14 reduced cell proliferation. Further studies showed that overexpression of DDX27 reduced epirubicin-induced DNA damage and apoptosis. Levels of DDX27 mRNA and protein were increased in early-stage gastric tumors, and may be a potential diagnostic and prognostic marker for GC. In summary, we used an integrative bioinformatics strategy to identify novel genes that are altered in GC and regulate resistance of GC cells to drugs in vitro., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2015
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37. Impact of adipogenic differentiation on stemness and osteogenic gene expression in extensive culture of human adipose-derived stem cells.
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Safwani WK, Makpol S, Sathapan S, and Chua K
- Abstract
Introduction: Adipose tissue is a source of multipotent adult stem cells. Most studies on human adipose-derived stem cells (ASC) have been on the early passages. Studies in extensive expansion have not been well established yet. In this study, we aim to investigate the effects of extensive expansion on the adipogenic differentiation capability of ASC., Material and Methods: The ability of ASC to undergo adipogenic differentiation in extensive expansion was evaluated by morphological changes, differentiation assay by using Oil Red O staining and changes in the genes expression levels of adipogenic genes, osteogenic genes and stemness genes using quantitative polymerase chain reaction (qPCR) after induction., Results: Morphological study showed that the formation of lipid droplets can be observed at all passages but decreased at P20 after induction. Data from qPCR showed that most adipogenicgenes expression increased significantlyat P5, P10 and P15 but decreased at P20 after induction. On the other hand, osteogenic genes showed no significant changes after adipogenic induction indicating low potentiality of adipogenic-induced ASC to become osteogenic cells. While stemness genes expression levels showed a decrease or no significant changes after adipogenic induction except Nanog3, which showed a significant increase at P15 and P20., Conclusions: The ability of ASC to differentiate into mature adipogenic cells decreased after P10 and the decrease in the osteogenics gene expression level during adipogenic induction suggested that the osteogenesis and adipogenesis are not parallel events.
- Published
- 2014
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38. Focal nodular hyperplasia-like lesion in a cirrhotic liver mimicking a cholangiocarcinoma.
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Loh JT, Chea YW, Lim KH, Wan WK, and Wong JS
- Subjects
- Bile Duct Neoplasms diagnostic imaging, Bile Ducts, Intrahepatic diagnostic imaging, Cholangiocarcinoma diagnostic imaging, Diagnosis, Differential, Female, Focal Nodular Hyperplasia diagnostic imaging, Humans, Liver pathology, Liver Cirrhosis diagnostic imaging, Magnetic Resonance Imaging, Middle Aged, Tomography, X-Ray Computed, Bile Duct Neoplasms pathology, Bile Ducts, Intrahepatic pathology, Cholangiocarcinoma pathology, Focal Nodular Hyperplasia pathology, Liver Cirrhosis pathology
- Published
- 2014
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39. Myxoid perineurioma in a transplanted kidney.
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Gan VH, Wan WK, and Tan YH
- Subjects
- Adult, Humans, Immunohistochemistry, Kidney diagnostic imaging, Kidney pathology, Kidney Neoplasms diagnostic imaging, Kidney Neoplasms pathology, Magnetic Resonance Imaging, Male, Nephrectomy methods, Nerve Sheath Neoplasms diagnostic imaging, Nerve Sheath Neoplasms pathology, Treatment Outcome, Ultrasonography, Kidney Neoplasms complications, Kidney Transplantation adverse effects, Nerve Sheath Neoplasms complications, Renal Insufficiency surgery
- Abstract
Perineuriomas are rare, benign peripheral nerve sheath tumors, most commonly found in the extremities and trunks. A handful of cases have been reported to arise from the retroperitoneum and in kidneys. To our knowledge, this is the first reported case of a myxoid perineurioma arising from a transplanted kidney. The patient is a 40-year-old Chinese male with end-stage kidney disease secondary to chronic sclerosing glomerulonephritis. He has a nonfunctioning renal graft in his right iliac fossa and a functioning graft in the left. Routine imaging found a mass in the nonfunctioning graft which was increasing in size. He underwent graft nephrectomy and histology revealed a myxoid perineurioma with no atypical features or malignancy., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
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40. Recurrence and histological evolution of dysembryoplastic neuroepithelial tumor: A case report and review of the literature.
- Author
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Chao L, Tao XB, Jun YK, Xia HH, Wan WK, and Tao QS
- Abstract
Studies of recurrent dysembryoplastic neuroepithelial tumors (DNTs) are distinctly rare. The present study reports the case of a 15-year-old female with a temporal lobe DNT, which recurred and transformed into an astrocytoma (WHO grade II) five years after an initial gross total resection (GTR). Furthermore, all the previous studies on recurrent DNT are reviewed. Although the majority of DNT cases demonstrate benign behavior, recurrent DNTs have been observed following a GTR of the tumor. Patients do not appear to benefit from post-operative adjuvant therapy, and inappropriate radiotherapy or chemotherapy may result in tumor recurrence or malignant transformation. The prognosis is favorable if a GTR of the recurrent tumor is achieved. The use of regular imaging examinations and the maintenance of a long-term follow-up is of importance following a tumor resection.
- Published
- 2013
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41. Alteration of gene expression levels during osteogenic induction of human adipose derived stem cells in long-term culture.
- Author
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Safwani WK, Makpol S, Sathapan S, and Chua KH
- Subjects
- Adipose Tissue metabolism, Adult, Biopsy, Cell Differentiation physiology, Cell Separation methods, Cells, Cultured, Fatty Acid-Binding Proteins genetics, Fatty Acid-Binding Proteins metabolism, Humans, In Vitro Techniques, Lipoprotein Lipase genetics, Lipoprotein Lipase metabolism, Middle Aged, PPAR gamma genetics, PPAR gamma metabolism, Pluripotent Stem Cells metabolism, Time Factors, Adipose Tissue pathology, Cell Differentiation genetics, Gene Expression Regulation physiology, Osteogenesis genetics, Osteogenesis physiology, Pluripotent Stem Cells pathology
- Abstract
Adipose tissue is a source of multipotent stem cells and it has the ability to differentiate into several types of cell lineages such as neuron cells, osteogenic and adipogenic cells. Most studies on human adipose-derived stem cells (ASCs) have been carried out at the early passages. For clinical usage, ASCs need to be expanded in vitro for a period of time to get sufficient cells for transplantation into patients. However, the impact of long-term culture on ASCs molecular characteristics has not been established yet. Several studies have also shown that osteogenic and adipogenic cells have the ability to switch pathways during in vitro culture as they share the same progenitor cells. This data is important to ensure their functionality and efficacy before being used clinically in the treatment of bone diseases. Therefore, we aim to investigate the effect of long-term culture on the adipogenic, stemness and osteogenic genes expression during osteogenic induction of ASCs. In this study, the molecular characteristics of ASCs during osteogenic induction in long-term culture was analysed by observing their morphological changes during induction, analysis of cell mineralization using Alizarin Red staining and gene expression changes using quantitative RT-PCR. Morphologically, cell mineralization at P20 was less compared to P5, P10 and P15. Adipogenesis was not observed as negative lipid droplets formation was recorded during induction. The quantitative PCR data showed that adipogenic genes expression e.g. LPL and AP2 decreased but PPAR-γ was increased after osteogenic induction in long-term culture. Most stemness genes decreased at P5 and P10 but showed no significant changes at P15 and P20. While most osteogenic genes increased after osteogenic induction at all passages. When compared among passages after induction, Runx showed a significant increased at P20 while BSP, OSP and ALP decreased at later passage (P15 and P20). During long-term culture, ASCs were only able to differentiate into immature osteogenic cells.
- Published
- 2013
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42. Brain metastases as a cause of malignant cerebrospinal fluid ascites: case report and review of the literature.
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Low YY, Thomas J, Wan WK, and Ng WH
- Subjects
- Brain pathology, Brain Neoplasms surgery, Breast Neoplasms pathology, Carcinoma, Ductal, Breast pathology, Fatal Outcome, Female, Humans, Magnetic Resonance Imaging, Middle Aged, Ascites etiology, Brain Neoplasms secondary, Cerebrospinal Fluid, Hydrocephalus etiology, Neoplasm Metastasis, Ventriculoperitoneal Shunt adverse effects
- Abstract
The development of cerebrospinal fluid ascites after a ventriculo-peritoneal shunt operation is an extremely rare complication. There have been only sporadic case reports and small series reviews published in regards to this condition. They are usually found in the context of primary brain tumors, usually affecting the pediatric population. We present an unusual case of a patient with known metastatic breast carcinoma to the brain who develops malignant cerebrospinal fluid ascites after a ventriculo-peritoneal shunt insertion. This is the first known adult case of a metastatic breast primary to the brain causing tumor dissemination via a ventriculo-peritoneal shunt.
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- 2012
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43. Multidimensional identification of tissue biomarkers of gastric cancer.
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Guo T, Fan L, Ng WH, Zhu Y, Ho M, Wan WK, Lim KH, Ong WS, Lee SS, Huang S, Kon OL, and Sze SK
- Subjects
- Cell Line, Tumor, Humans, Proteome metabolism, Tandem Mass Spectrometry, Tissue Array Analysis, Biomarkers, Tumor metabolism, Membrane Proteins metabolism, Stomach Neoplasms metabolism
- Abstract
Gastric cancer remains highly fatal due to a dearth of diagnostic biomarkers for early stage disease and molecular targets for therapy. Plasma membrane proteins, including cluster of differentiation (CD) proteins and receptor tyrosine kinases (RTKs), are a rich reservoir of biomarkers. Recognizing that interrogating plasma membrane proteins individually overlooks extensive interactions among them, we have systematically investigated the membrane proteomes and transcriptomes of six gastric cancer cell lines. Our data revealed aberrantly high expression of proteins whose functions accurately reflect the clinical phenotype of gastric cancer, and prioritized critical RTKs and CD proteins in gastric cancer. Expression of selected surface proteins was confirmed by flow cytometry and immunostaining of clinical gastric cancer tissues. Close to 90% of the gastric cancer tissues in a cohort showed up-regulation of at least one of four proteins, that is, MET, EPHA2, FGFR2, and CD104/ITGB4. All intestinal type gastric cancer tumors in this cohort overexpressed at least one of a panel of three proteins, MET, FGFR2, and EPHA2. This study reports the first quantitative global landscape of the surface proteome of gastric cancer cells and provides a shortlist of gastric cancer biomarkers.
- Published
- 2012
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44. Exome sequencing of gastric adenocarcinoma identifies recurrent somatic mutations in cell adhesion and chromatin remodeling genes.
- Author
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Zang ZJ, Cutcutache I, Poon SL, Zhang SL, McPherson JR, Tao J, Rajasegaran V, Heng HL, Deng N, Gan A, Lim KH, Ong CK, Huang D, Chin SY, Tan IB, Ng CC, Yu W, Wu Y, Lee M, Wu J, Poh D, Wan WK, Rha SY, So J, Salto-Tellez M, Yeoh KG, Wong WK, Zhu YJ, Futreal PA, Pang B, Ruan Y, Hillmer AM, Bertrand D, Nagarajan N, Rozen S, Teh BT, and Tan P
- Subjects
- Case-Control Studies, DNA genetics, Gastric Mucosa metabolism, Humans, Microsatellite Instability, Polymerase Chain Reaction, Polymorphism, Single Nucleotide genetics, Sequence Analysis, DNA, Adenocarcinoma genetics, Cell Adhesion genetics, Chromatin Assembly and Disassembly genetics, Exome genetics, Genes, Tumor Suppressor, Mutation genetics, Stomach Neoplasms genetics
- Abstract
Gastric cancer is a major cause of global cancer mortality. We surveyed the spectrum of somatic alterations in gastric cancer by sequencing the exomes of 15 gastric adenocarcinomas and their matched normal DNAs. Frequently mutated genes in the adenocarcinomas included TP53 (11/15 tumors), PIK3CA (3/15) and ARID1A (3/15). Cell adhesion was the most enriched biological pathway among the frequently mutated genes. A prevalence screening confirmed mutations in FAT4, a cadherin family gene, in 5% of gastric cancers (6/110) and FAT4 genomic deletions in 4% (3/83) of gastric tumors. Frequent mutations in chromatin remodeling genes (ARID1A, MLL3 and MLL) also occurred in 47% of the gastric cancers. We detected ARID1A mutations in 8% of tumors (9/110), which were associated with concurrent PIK3CA mutations and microsatellite instability. In functional assays, we observed both FAT4 and ARID1A to exert tumor-suppressor activity. Somatic inactivation of FAT4 and ARID1A may thus be key tumorigenic events in a subset of gastric cancers.
- Published
- 2012
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45. The impact of long-term in vitro expansion on the senescence-associated markers of human adipose-derived stem cells.
- Author
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Safwani WK, Makpol S, Sathapan S, and Chua KH
- Subjects
- Biomarkers metabolism, Cell Cycle, Cell Differentiation, Cell Proliferation, Humans, Kinetics, Stem Cells enzymology, Time Factors, beta-Galactosidase metabolism, Adipose Tissue cytology, Cell Culture Techniques methods, Cellular Senescence, Stem Cells cytology, Stem Cells metabolism
- Abstract
Human adipose-derived stem cells (ASCs) have generated a great deal of excitement in regenerative medicine. However, their safety and efficacy issue remain a major concern especially after long-term in vitro expansion. The aim of this study was to investigate the fundamental changes of ASCs in long-term culture by studying the morphological feature, growth kinetic, surface marker expressions, expression level of the senescence-associated genes, cell cycle distribution and ß-galactosidase activity. Human ASCs were harvested from lipoaspirate obtained from 6 patients. All the parameters mentioned above were measured at P5, P10, P15 and P20. Data were subjected to one-way analysis of variance with a Tukey post hoc test to determine significance difference (P < 0.05). The data showed that growth of ASCs reduced in long-term culture and the ß-galactosidase activity was significantly increased at later passage (P20). The morphology of ASCs in long-term culture showed the manifestation of senescent feature at P15 and P20. Significant alteration in the senescence-associated genes expression levels was observed in MMP1, p21, Rb and Cyclin D1 at P15 and P20. Significant increase in CD45 and HLA DR DQ DP surface marker was observed at P20. While cell cycle analysis showed significant decrease in percentage of ASCs at S and G2/M phase at later passage (P15). Our data showed ASCs cultured beyond P10 favours the senescence pathway and its clinical usage in cell-based therapy may be limited.
- Published
- 2012
- Full Text
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46. Intrinsic subtypes of gastric cancer, based on gene expression pattern, predict survival and respond differently to chemotherapy.
- Author
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Tan IB, Ivanova T, Lim KH, Ong CW, Deng N, Lee J, Tan SH, Wu J, Lee MH, Ooi CH, Rha SY, Wong WK, Boussioutas A, Yeoh KG, So J, Yong WP, Tsuburaya A, Grabsch H, Toh HC, Rozen S, Cheong JH, Noh SH, Wan WK, Ajani JA, Lee JS, Tellez MS, and Tan P
- Subjects
- Adult, Aged, Aged, 80 and over, Cisplatin therapeutic use, Female, Fluorouracil therapeutic use, Humans, Kaplan-Meier Estimate, Male, Microarray Analysis, Middle Aged, Organoplatinum Compounds therapeutic use, Oxaliplatin, Prognosis, Proportional Hazards Models, Stomach Neoplasms drug therapy, Stomach Neoplasms pathology, Survival Rate, Young Adult, Biomarkers, Tumor metabolism, Cadherins metabolism, Galectin 4 metabolism, Gene Expression Profiling, Stomach Neoplasms classification, Stomach Neoplasms genetics
- Abstract
Background & Aims: Gastric cancer (GC) is a heterogeneous disease comprising multiple subtypes that have distinct biological properties and effects in patients. We sought to identify new, intrinsic subtypes of GC by gene expression analysis of a large panel of GC cell lines. We tested if these subtypes might be associated with differences in patient survival times and responses to various standard-of-care cytotoxic drugs., Methods: We analyzed gene expression profiles for 37 GC cell lines to identify intrinsic GC subtypes. These subtypes were validated in primary tumors from 521 patients in 4 independent cohorts, where the subtypes were determined by either expression profiling or subtype-specific immunohistochemical markers (LGALS4, CDH17). In vitro sensitivity to 3 chemotherapy drugs (5-fluorouracil, cisplatin, oxaliplatin) was also assessed., Results: Unsupervised cell line analysis identified 2 major intrinsic genomic subtypes (G-INT and G-DIF) that had distinct patterns of gene expression. The intrinsic subtypes, but not subtypes based on Lauren's histopathologic classification, were prognostic of survival, based on univariate and multivariate analysis in multiple patient cohorts. The G-INT cell lines were significantly more sensitive to 5-fluorouracil and oxaliplatin, but more resistant to cisplatin, than the G-DIF cell lines. In patients, intrinsic subtypes were associated with survival time following adjuvant, 5-fluorouracil-based therapy., Conclusions: Intrinsic subtypes of GC, based on distinct patterns of expression, are associated with patient survival and response to chemotherapy. Classification of GC based on intrinsic subtypes might be used to determine prognosis and customize therapy., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)
- Published
- 2011
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47. Liver transplantation in an adult with citrullinaemia type 2.
- Author
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Tan HH, Chow WC, Lim KH, Wan WK, Chung AY, Cheow PC, and Tan CK
- Abstract
Citrullinaemia is a urea cycle defect that results from a deficiency of the enzyme arginosuccinate synthetase. Type 1 disease is diagnosed in childhood, whereas Type 2 disease is adult onset. We report the outcome of a patient with citrullinemia Type 2 who received a liver transplant at our center and the implications of this diagnosis in liver transplantation.
- Published
- 2011
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48. Foetal rhabdomyoma with fine-needle aspirate cytology correlation.
- Author
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Wan WK, Sng TY, Goh HK, and Hwang SG
- Subjects
- Biomarkers, Tumor analysis, Biopsy, Fine-Needle, Child, Diagnosis, Differential, Female, Head and Neck Neoplasms surgery, Humans, Neck Muscles pathology, Neck Muscles surgery, Rhabdomyoma surgery, Soft Tissue Neoplasms surgery, Head and Neck Neoplasms pathology, Rhabdomyoma pathology, Soft Tissue Neoplasms pathology
- Abstract
A case of intermediate form of foetal rhabdomyoma with cytological correlation is reported in a ten-year-old girl who presented with a lump in the right neck region. Fine-needle aspirate of the lump was performed. Cytological findings were that of spindled cells and rhabdomyoblasts with abundant eosinophilic cytoplasm. The lesion was subsequently excised. Histology showed a well-circumscribed cellular lesion composed of oval- to spindle-shaped cells. There were interspersed immature skeletal muscle cells with uniform nuclei and eosinophilic tapered cytoplasm and ganglion-like rhabdomyoblasts. No marked cellular atypia or prominent mitoses was noted. Immunohistochemically, the tumour cells showed positivity for muscle specific actin, myoglobin and myogenin. There was focal positivity for desmin. The patient showed no evidence of local recurrence or metastasis after a 32-month follow-up. This is believed to be the first case report of cytological findings in an intermediate form of foetal rhabdomyoma.
- Published
- 2009
49. A new chemoimmunotherapy regimen (OXAFI) for advanced hepatocellular carcinoma.
- Author
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Ang MK, Poon D, Foo KF, Chung YF, Chow P, Wan WK, Thng CH, and Ooi L
- Subjects
- Adult, Carcinoma, Hepatocellular pathology, Doxorubicin administration & dosage, Doxorubicin adverse effects, Female, Humans, Interferon alpha-2, Interferon-alpha administration & dosage, Interferon-alpha adverse effects, Liver Neoplasms pathology, Male, Middle Aged, Neoplasm Staging, Organoplatinum Compounds administration & dosage, Organoplatinum Compounds adverse effects, Oxaliplatin, Recombinant Proteins, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Carcinoma, Hepatocellular drug therapy, Liver Neoplasms drug therapy
- Abstract
Background: Chemotherapeutic treatment options for advanced unresectable and/or metastatic hepatocellular carcinoma (HCC) are limited. Currently available treatments are associated with low response rates and little evidence of improved survival, so we evaluated a new chemoimmunotherapy regimen., Methods: Seven patients with unresectable and/or metastatic HCC were treated with intravenous oxaliplatin (30mg/m2) and doxorubicin (20mg/m2) given on days 1, 8 and 15 in a 28-day cycle, a daily continuous infusion of fluorouracil (200mg/m2) and subcutaneous interferon alfa-2b 5 MU administered thrice weekly (OXAFI). Treatment was administered to a maximum of six cycles. Data on the response to treatment, toxicity, surgical procedures and survival outcome was reviewed., Results: The best response was three partial responses, three stable disease responses and one progressive disease response. Two patients underwent interval hepatic resection, and histological analysis in one patient showed a complete pathological response. Another patient underwent a liver transplant after four cycles of treatment. These three patients were alive with no evidence of disease at 23, 21 and 18 months follow-up, respectively. At a median follow-up of 14 months (range 2-23 months), one patient died 2 months after diagnosis due to progressive disease, while all six other patients were alive. Neutropenia was the predominant toxicity, but there were no episodes of febrile neutropenia, hospital admissions or deaths. There were no cases of hepatitis B virus re-activation., Conclusions: OXAFI shows activity in HCC and has manageable toxicity. Complete pathological remission is possible with this regimen.
- Published
- 2008
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- View/download PDF
50. Use of degradable and nondegradable nanomaterials for controlled release.
- Author
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Wan WK, Yang L, and Padavan DT
- Subjects
- Particle Size, Absorbable Implants, Delayed-Action Preparations chemistry, Drug Carriers chemistry, Nanomedicine methods, Nanostructures chemistry, Nanostructures ultrastructure, Pharmaceutical Vehicles chemistry
- Abstract
Drug-delivery devices are fundamentally important in improving the pharmacological profiles of therapeutic molecules. Nanocontrolled-release systems are attracting a lot of attention currently owing to their large surface area and their ability to target delivery to specific sites in the human body. In addition, they can penetrate the cell membrane for gene, nucleic acid and bioactive peptide/protein delivery. Representative applications of nanodrug-delivery systems include controlled-release wound dressings, controlled-release scaffolds for tissue regeneration and implantable biodegradable nanomaterial-based medical devices integrated with drug-delivery functions. We review the present status and future perspectives of various types of nanocontrolled-release systems. Although many of the well-established degradable and nondegradable controlled-release vehicles are being investigated for their processing into nanocarriers, several new emerging nanomaterials are being studied for their controlled-release properties. The release of multiple bioactive agents, each with its own kinetic profile, is becoming possible. In addition, integration of the nanocontrolled-release systems with other desirable functions to create new, cross-discipline applications can also be realized.
- Published
- 2007
- Full Text
- View/download PDF
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