Tiffany Chan

McMaster University, Hamilton, Ontario, Canada

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Publications (8)19.51 Total impact

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    ABSTRACT: Background/Purpose The 64-slice multidetector CT (64-MDCT) has bolstered the sensitivity and specificity of coronary CT angiography (CCTA) for detecting coronary artery disease. We performed this study to understand the current status of CCTA using 64-MDCT, so as to determine further promotion and optimal regulation schemes of CCTA in Taiwan. Methods Information about CCTA from 68 domestic hospitals with 64-MDCT was collected by means of a questionnaire from July 2009 to January 2010. The studied details included: (1) the implementation background of CCTA; (2) the interdisciplinary cooperation and report processing of CCTA; and (3) the promotion strategy of CCTA. Results The majority of CCTA sites (89.7%) were administered by diagnostic radiologists. Most cardiologists and cardiac surgeons have confirmed its clinical value by referring patients to undergo CCTA. Of the CCTA reports by radiologists, 41.2% had their report supplemented by referring cardiologists. Such cooperation amongst specialists promoted the development of CCTA. Of CCTA studies, 89.7% included coronary calcium scoring. Most (60.3%) respondents asserted the cost of a study to be 15,000 to 20,000 new Taiwan dollars. Nearly two-fifths (41.2%) of the respondents supported the restriction of subjects for CCTA to those who were high risk group for coronary artery disease or those > 40 years of age. Conclusion Diagnostic radiologists are primarily in charge of managing CCTA sites in Taiwan. The interdisciplinary cooperation amongst radiologists and cardiologists in reporting CCTA may expedite the development of CCTA. The domestic radiologists are expected to standardize the process, which includes interpreting and reporting CCTA findings.
    Journal of the Formosan Medical Association 01/2014; 113(2):124–132. · 1.00 Impact Factor
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    ABSTRACT: This work aims to validate the clinical significance of coronary artery calcium score (CACS) in predicting coronary artery disease (CAD) and cardiac events in 100 symptomatic patients (aged 37-87 years, mean 62.5, 81 males) that were followed up for a mean of 5 years. Our results showed that patients with CAD and cardiac events had significantly higher CACS than those without CAD and cardiac events, respectively. The corresponding data were 1450.42 ± 3471.24 versus 130 ± 188.29 (P < 0.001) for CAD, and 1558.67 ± 513.29 versus 400.46 ± 104.47 (P = 0.031) for cardiac events. Of 72 patients with CAD, cardiac events were found in 56 (77.7%) patients. The prevalence of cardiac events in our cohort was 13.3% for calcium score 0, 50% for score 11-100, 56% for score 101-400, 68.7% for score 401-1,000, and 75.0% for score >1000. Increased CACS (>100) was also associated with an increased frequency of multi-vessel disease. Nonetheless, 3 (20%) out of 15 patients with zero CACS had single-vessel disease. Significant correlation (P < 0.001) was observed between CACS and CAD on a vessel-based analysis for coronary arteries. It is concluded that CACS is significantly correlated with CAD and cardiac events.
    BioMed research international. 01/2013; 2013:472347.
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    ABSTRACT: Influenza viral infection results in excessive pulmonary inflammation that has been linked to the damage caused by immune responses and viral replication. The multifunctional cytokine interleukin (IL-15), influences the proliferation and maintenance of immune cells such as CD8(+) T cells and natural killer (NK) cells. Here we show that IL-15(-/-) mice are protected from lethal influenza infection. Irrespective of the mouse strains, the protection observed was linked to the lack of NK cells. Increased survival in the IL-15(-/-) or NK1.1(+) cell-depleted wild-type mice was associated with significantly lower lung lesions as well as decreased mononuclear cells and neutrophils in the airway lumen. Levels of interleukin 10 were significantly higher and levels of proinflammatory cytokines, including interleukin 6 and interleukin 12, were significantly lower in the bronchoalveolar lavage fluid from IL-15(-/-) and NK1.1(+) cell-depleted wild-type mice than in that from control mice. Our data suggest that NK cells significantly augment pulmonary inflammation, contributing to the pathogenesis of influenza infection.
    The Journal of Infectious Diseases 05/2012; 206(2):167-77. · 5.85 Impact Factor
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    ABSTRACT: The influence of coronary calcification on the diagnostic performance of coronary computed tomography angiography (CTA) remains controversial. This study attempts to assess the effect of coronary calcium score (CS) on the diagnostic accuracy of detecting coronary artery disease (CAD) using 64-row multidetector computed tomography (MDCT). Over a period of 2 years and 9 months, 113 symptomatic patients (37-87 year-old, mean 62.3, 92 males) underwent 64-row MDCT for coronary CS and CTA. All had conventional coronary angiography (CCA) within 90 (mean 9.6) days. Coronary CTA was evaluated with CCA as the gold standard. Of 113 patients, 18 patients had a CS of 0, 18 had scores between 1 and 100, 27 between 101 and 400, and 50 had scores >400. With respect to patient-based analysis, the accuracy of CTA was 90.3%, the sensitivity was 95%, and the specificity was 78.8%. Regarding patients with CS > 400, the accuracy, sensitivity, and specificity were 92, 95.6, and 60%, respectively. On vessel-based analysis, the specificity of CTA in different vessels with CS < [double bond] 400 and CS > 400 was as follows: right coronary artery 87.1% versus 87.5% (P = 0.924); left main artery 94.8% versus 66.7% (P = 0.173); left anterior descending artery 77.1% versus 27.3% (P = 0.001); and left circumflex artery 83.3% versus 42.8% (P = 0.011). A high CS does not significantly affect the diagnostic accuracy and sensitivity of CTA; however, it significantly decreases the specificity, particularly the left anterior descending and left circumflex arteries.
    The international journal of cardiovascular imaging 12/2011; 27 Suppl 1:37-42. · 2.15 Impact Factor
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    ABSTRACT: Fimbriae H protein (FimH) is a novel TLR4 ligand that has been shown to stimulate the innate immune system and elicits protective responses against bacterial and viral infections. Here, we evaluated the protective role of local delivery of FimH against influenza A infection in a mouse model. We show that intranasal delivery of FimH prior to lethal challenge with influenza A virus, resulted in decreased morbidity and mortality in wild-type, but not TLR4(-/-), mice. Importantly, FimH was able to reduce the early viral burden in the lung leading to minimal cell infiltration into the airway lumen and reduced pulmonary pathology following infection in wild type mice compared to TLR4(-/-) mice. Local delivery of FimH to C57BL/6, not TLR4(-/-), mice in a prophylactic manner increased the IL-12 and RANTES responses as well as neutrophil recruitment into the airway lumen. These effects correlate to the course of influenza infection. The FimH-mediated antiviral response against influenza virus appears to be partially dependent on alveolar macrophages. The antiviral effects are likely mediated by the innate mediators (TNF-α, IL-12 or RANTES) and/or by activation of a feedback inhibition loop to curtail the pulmonary inflammation possibly be the potential mechanisms involved in FimH-mediated protection. FimH thus holds promise to be a possible prophylactic mean of control against influenza viral infection.
    Antiviral research 09/2011; 92(2):346-55. · 3.61 Impact Factor
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    ABSTRACT: Herpes simplex virus type 2 (HSV-2) is becoming increasingly prevalent worldwide, despite the widespread use of antiviral drugs. Its ability to evade the immune system and establish a latent infection has made it difficult to develop an effective vaccine. Our understanding of the immune response against HSV-2 remains complex and involves a balance between innate signaling pathways and the adaptive immune response. Primary infection with HSV-2 induces toll-like receptor (TLR)-mediated Type I interferon (IFN) production, which establishes an antiviral state and activates multiple cell types, including natural killer cells and plasmacytoid dendritic cells. This innate response is not only crucial for controlling initial infection, but also for priming adaptive immune responses as well. Both humoral and cellular responses encompass adaptive immunity, although the former has been shown to be dispensable in response to HSV-2. Recently, numerous studies have attributed IFNγ producing CD4(+) T cells to be the key effector molecule responsible for clearing infection. It remains unclear whether regulatory T (Treg) cells are a source of aid or hindrance in the clearance of disease. Collectively, this review highlights the balance between innate and adaptive effector responses that contribute to the control and clearance of HSV-2 infection.
    Journal of Reproductive Immunology 02/2011; 88(2):210-8. · 2.34 Impact Factor
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    ABSTRACT: During activation, macrophages undergo physiological changes affecting their surface protein expression and cytokine production and have been subsequently categorized into M1 (classically-activated) and M2 (alternatively-activated) macrophages. It remains unclear which lymphocyte population provides the immune microenvironment to regulate macrophage polarization. In this study, we establish a functional and phenotypic profile of peritoneal macrophages from C57BL/6 wild-type mice. We also showed that Rag1(-/-) and Rag2(-/-)γc(-/-) mice have similar, exaggerated M1 characteristics in comparison to control mice, suggesting that NK and/or NK-T cells may not be essential in this process. By controlling for environmental factors, we determine that lymphocyte-derived cytokines, rather than inherent properties of macrophages themselves, are crucial for their regulation. Lastly, we report that macrophages from CD4(-/-) mice display an M1 profile, suggesting that CD4(+) T-cells play a dominant role over other lymphocyte populations in providing the cytokine environment for regulating macrophages towards an M2 profile under normal wild-type conditions.
    Cellular Immunology 10/2010; 266(2):180-6. · 1.74 Impact Factor
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    ABSTRACT: Natural Killer cells can distinguish between healthy and malignant cells and have the unique ability to lyse tumour cells without prior sensitization. Differences between murine and human NK cells complicate the translation of this knowledge into useful therapeutics. Humanized mouse models that support the development of human leukocytes are a promising avenue of research that aims to address this problem. Here we provide an in-depth phenotypic analysis of human NK cells in Balb/c Rag2(-/-)γ(c)(-/-) mice reconstituted with human hematopoietic stem cells. We have examined the development of NK cells in bone marrow, thymous, spleen, lymph node (LN) and liver. Interestingly, in naive reconstituted mice, NK cells were found in thymus and LN, but not in bone marrow. These NK cells expressed several inhibitory and activating receptors needed for malignant cell detection. Furthermore, we confirm that administration of recombinant human interleukin-15 (rhIL-15) or Ad-vector expressing hIL-15 is able to significantly enhance NK cell development and maturation, particularly in bone marrow and liver, in this model. Our results suggest that human NK cells developed in mice may have phenotypes and tissue distributions similar to those seen in human.
    Immunobiology 01/2010; 216(1-2):218-24. · 2.81 Impact Factor

Publication Stats

66 Citations
19.51 Total Impact Points

Institutions

  • 2010–2014
    • McMaster University
      • • Michael G. DeGroote School of Medicine
      • • Department of Pathology and Molecular Medicine
      Hamilton, Ontario, Canada
  • 2011–2013
    • Chang Gung University
      • College of Medicine
      Taoyuan, Taiwan, Taiwan