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Search Results: 1 - 10 of 28893 matches for " Paul KS Chan "
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Human papillomavirus type 58: the unique role in cervical cancers in East Asia
Paul KS Chan
Cell & Bioscience , 2012, DOI: 10.1186/2045-3701-2-17
Abstract: A high prevalence of HPV58 among squamous cell carcinoma has been reported from China (28% in Shanghai, 10% in Hong Kong and 10% in Taiwan) and other countries in East Asia including Korea (16%) and Japan (8%). HPV58 ranks the third in Asia overall, but contributes to only 3.3% of cervical cancers globally. The reasons for a difference in disease attribution may lie on the host as well as the virus itself. HLA-DQB1*06 was found to associate with a higher risk of developing HPV58-positive cervical neoplasia in Hong Kong women, but not neoplasia caused by other HPV types. An HPV58 variant (E7 T20I, G63S) commonly detected in Hong Kong was found to confer a 6.9-fold higher risk of developing cervical cancer compared to other variants. A study involving 15 countries/cities has shown a predilection in the distribution of HPV58 variant lineages. Sublineage A1, the prototype derived from a cancer patient in Japan, was rare worldwide except in Asia.HPV58 accounts for a larger share of disease burden in East Asia, which may be a result of differences in host genetics as well as the oncogenicity of circulating variants. These unique characteristics of HPV58 should be considered in the development of next generation vaccines and diagnostic assays.Human papillomavirus (HPV) plays a necessary, though insufficient, role in the development of cervical cancer, which is the third most common cancer in women worldwide, just following breast and colorectal cancers [1,2]. It has been estimated that about 530 000 new cases and 275 000 deaths from the disease occurred in 2008. The incidence of cervical cancer varies dramatically across the world, which is mainly related to the availability and accessibility of cervical screening programs. Most places in South America and South and West Africa have an age-standardized incidence above 20 per 100 000 women per year, and some places in these regions have reached 40 per 100 000 women per year. In contrast, the age-standardized incidence rates
Apoptosis, cytokine and chemokine induction by non-structural 1 (NS1) proteins encoded by different influenza subtypes
WY Lam, Apple CM Yeung, Paul KS Chan
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-554
Abstract: Human lung epithelial cells (NCI-H292) was used as an in-vitro model to study cytokine/chemokine production and apoptosis induced by transfection of NS1 mRNA encoded by seven infleunza subtypes (seasonal and pandemic H1, H2, H3, H5, H7, and H9), respectively.The results showed that CXCL-10/IP10 was most prominently induced (> 1000 folds) and IL-6 was slightly induced (< 10 folds) by all subtypes. A subtype-dependent pattern was observed for CCL-2/MCP-1, CCL3/MIP-1α, CCL-5/RANTES and CXCL-9/MIG; where induction by H5N1 was much higher than all other subtypes examined. All subtypes induced a similar temporal profile of apoptosis following transfection. The level of apoptosis induced by H5N1 was remarkably higher than all others. The cytokine/chemokine and apoptosis inducing ability of the 2009 pandemic H1N1 was similar to previous seasonal strains.In conclusion, the NS1 protein encoded by H5N1 carries a remarkably different property as compared to other avian and human subtypes, and is one of the keys to its high pathogenicity. NCI-H292 cells system proves to be a good in-vitro model to delineate the property of NS1 proteins.Influenza A viruses are major animal and human pathogens with potential to cause pandemics. Avian subtypes H5N1, H7N7 and H9N2 have repeatedly crossed the species barrier to infect humans [1-8]. Since 2003, there have been repeated outbreaks of H5N1 in poultries and sporadic human infections associated with high mortality [8,9]. The recently emerged swine-origin influenza A virus (2009 pandemic H1N1 influenza virus - 2009 pdmH1N1) has spread globally within a few months following the initial detection in Mexico and United States in April 2009, resulting in another influenza pandemic as declared by the World Health Organization (WHO) on June 11 2009 [10]. Although most of the infections are associated with a mild, self-limiting influenza-like illness; the fact that some severe and even fatal outcomes have been observed in individuals without underl
Polymerase activity of hybrid ribonucleoprotein complexes generated from reassortment between 2009 pandemic H1N1 and seasonal H3N2 influenza A viruses
Wai Y Lam, Karry LK Ngai, Paul KS Chan
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-528
Abstract: The 2009 pdmH1N1 vRNP showed a lower level of polymerase activity at 33°C compared to 37°C, a property remenisence of avian viruses. The 2009 pdmH1N1 vRNP was found to be more cold-sensitive than the WSN or H3N2 vRNP. Substituion of 2009 pdmH1N1 vRNP with H3N2-derived-subunits, and vice versa, still retained a substantial level of polymerase activity, which is probably compartable with survival. When the 2009 pdmH1N1 vRNP was substituted with H3N2 PA, a significant increase in activity was observed; whereas when H3N2 vRNP was substituted with 2009 pdmH1N1 PA, a significant decrease in activity occurred. Although, the polymerase basic protein 2 (PB2) of 2009 pdmH1N1 was originated from an avian virus, substitution of this subunit with H3N2 PB2 did not change its polymerase activity in human cells.In conclusion, our data suggest that hybrid vRNPs resulted from reassortment between 2009 pdmH1N1 and H3N2 viruses could still retain a substantial level of polymerase activity. Substituion of the subunit PA confers the most prominent effect on polymerase activity. Further studies to explore the determinants for polymerase activity of influenza viruses in associate with other factors that limit host specificity are warrant.In April 2009, the Centers for Disease Control and Prevention (CDC) at Atlanta reported that a new influenza virus was found in Mexico and the United States [1]. The new influenza A H1N1 virus was soon characterized [2,3] to be a triple reassortant derived from human, avian and swine influenza viruses [3-5]. The virus spread rapidly worldwide [6] and the World Health Organization (WHO) declared that the pandemic has reached phase 6 on June 11 2009 [7]. Currently, the virus is still circulating worldwide [7].Influenza viruses exhibit a restricted host range with limited replication in other species [8-10]. However, on rare occasions, influenza viruses can cross species barrier and adapt to a new host giving rise to a new lineage. Adaptation to a new species
Inaccurate identification of rotavirus genotype G9 as genotype G3 strains due to primer mismatch
Mitui Marcelo,Chandrasena TGA,Chan Paul KS,Rajindrajith Shaman
Virology Journal , 2012, DOI: 10.1186/1743-422x-9-144
Abstract: Reverse transcription (RT)-PCR is now the standard method for typing group A rotaviruses (RVA) to monitor the circulating genotypes in a population. Selection of primers that can accurately type the circulating genotypes is crucial in the context of vaccine introduction and correctly interpreting the impact of vaccination on strain distribution. To our knowledge this study is the first report from Asia of misidentification of genotype G9 as G3 due to a primer-template mismatch. We tested two published G-genotype specific primers sets, designed by Gouvea and colleagues (Set A) and Iturriza‐Gomara and colleagues (Set B) on RVA from Hong Kong and Sri Lanka. Among 52 rotaviruses typed as G3 by set A primers, 36 (69.2%) were identified as G9 by nucleotide sequencing and set B primers. Moreover, of 300 rotaviruses tested, 28.3% were untypable by set A primers whereas only 12.3% were untypable by set B primers. Our findings reinforce the need to periodically monitor the primers used for RVA genotyping.
Mutations around interferon sensitivity-determining region: A pilot resistance report of hepatitis C virus 1b in a Hong Kong population
Xiao-Ming Zhou,Paul KS Chan,John S Tam
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i48.5317
Abstract: AIM: To explore mutations around the interferon sensitivity-determining region (ISDR) which are associated with the resistance of hepatitis C virus 1b (HCV-1b) to interferon-α treatment. METHODS: Thirty-seven HCV-1b samples were obtained from Hong Kong patients who had completed the combined interferon-α/ribavirin treatment for more than one year with available response data. Nineteen of them were sustained virological responders, while 18 were non-responders. The amino acid sequences of the extended ISDR (eISDR) covering 64 amino acids upstream and 67 amino acids downstream from the previously reported ISDR were analyzed. RESULTS: One amino acid variation (I2268V, P = 0.023) was significantly correlated with treatment outcome in this pilot study with a limited number of patients, while two amino acid variations (R2260H, P = 0.05 and S2278T, P = 0.05) were weakly associated with treatment outcome. The extent of amino acid variations within the ISDR or eISDR was not correlated with treatment outcome as previously reported. CONCLUSION: Three amino acid mutations near but outside of ISDR may associate with interferon treatment resistance of HCV-1b patients in Hong Kong.
Profiles of cytokine and chemokine gene expression in human pulmonary epithelial cells induced by human and avian influenza viruses
WY Lam, Apple CM Yeung, Ida MT Chu, Paul KS Chan
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-344
Abstract: Avian influenza viruses (AIV) are classified into two pathotypes. The highly pathogenic type (HPAIV) causes severe disease with a high mortality rate, whereas the low pathogenic type (LPAIV) causes asymptomatic infection or a mild disease [1,2]. Human infection with HPAIV H5N1 was first detected in Hong Kong in 1997 [3-5]. As at July 2009, more than 400 human infections have been reported to the World health Organization (WHO), and with an average case fatality rate of greater than 60% (WHO 2010). Hypercytokinaemia was consistently reported from patients with fatal H5N1 infection [4,6-9].Influenza viruses of the H9 subtype have been widely circulated in the world since their first detection from turkeys in Wisconsin in 1966 [10]. H9N2 viruses had caused disease outbreaks in chicken, ducks and pigs in many parts of the world including China, Germany, Hong Kong, Indonesia, Iran, Ireland, Israel, Italy, Jordan, Pakistan, Saudi Arabia, South Africa, South Korea, UAE, and USA in recent years [11-18]. In 1999 and 2003, self-limiting mild human infections with LPAIV H9N2 viruses were recorded in Hong Kong [19]. Some avian H9 viruses have acquired receptor binding characteristics typical of human strains, which may increase the potential for reassortment in both human and swine respiratory tracts [20-22].The respiratory epithelial cells are the primary targets for HPAIV and LPAIV infections [23-25]. In response to HPAIV and LPAIV, these cells are likely to play a critical role in inflammatory response, and in the initiation of innate and subsequently adaptive immune responses [3,25-29]. Recently, it has been reported that HPAIV H5N1 infection of epithelial cells induce the expression of several proinflammatory cytokines and chemokines both in vitro and in vivo, which could be linked to the consequence of fatal hypercytokinemia [8,30-32].The biological basis accounting for the difference in disease severity among different avian influenza virus infections in humans remains u
Willingness to accept H1N1 pandemic influenza vaccine: A cross-sectional study of Hong Kong community nurses
Samuel YS Wong, Eliza LY Wong, Josette Chor, Kenny Kung, Paul KS Chan, Carmen Wong, Sian M Griffiths
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-316
Abstract: 401 questionnaires were posted from June 24, 2009 to June 30, 2009 to community nurses with 67% response rate. Results of the 267 respondents on their willingness to accept influenza A (H1N1) vaccine were analyzed.Twenty-seven percent of respondents were willing to accept influenza vaccination if vaccines were available. Having been vaccinated for seasonable influenza in the previous 12 months were significantly independently associated with their willingness to accept influenza A (H1N1) vaccination (OR = 4.03; 95% CI: 2.03-7.98).Similar to previous findings conducted in hospital healthcare workers and nurses, we confirmed that the willingness of community nurses to accept influenza A (H1N1) vaccination is low. Future studies that evaluate interventions to address nurses' specific concerns or interventions that aim to raise the awareness among nurses on the importance of influenza A (H1N1) vaccination to protect vulnerable patient populations is needed.The 2009 pandemic of influenza A (H1N1) infection has alerted many governments to make preparedness plan to control the spread of influenza A (H1N1) infection. With evidence on the effectiveness of vaccination in the control and prevention of seasonal influenza [1,2], vaccination for pandemic influenza is one of the most important primary preventative measures to reduce the disease burden associated with influenza A (H1N1) infection [3].Several high risk groups have been identified as "the priority group" to receive the influenza A (H1N1) vaccination and among these, healthcare workers have been identified "as a first priority" to be vaccinated against influenza A (H1N1) by the World Health Organization [4,5]. Although it is considered essential for all healthcare workers to be immunized against influenza A (H1N1) to prevent the spread of influenza A (H1N1) to patients as the pandemic evolves, previous studies that have examined the acceptability of seasonal influenza vaccination among healthcare workers have generall
A simple and rapid approach for screening of SARS-coronavirus genotypes: an evaluation study
Grace TY Chung, Rossa WK Chiu, Jo LK Cheung, Yongjie Jin, Stephen SC Chim, Paul KS Chan, YM Dennis Lo
BMC Infectious Diseases , 2005, DOI: 10.1186/1471-2334-5-87
Abstract: Thirty SARS patients were recruited. Allelic discrimination assays were developed based on the use of fluorogenic oligonucleotide probes (TaqMan). Genotyping of the SARS-coronavirus isolates obtained from these patients were carried out by the allelic discrimination assays and confirmed by direct sequencing.Genotyping based on the allelic discrimination assays were fully concordant with direct sequencing. All of the 30 SARS-coronavirus genotypes studied were characteristic of genotypes previously documented to be associated with the latter part of the epidemic. Seven of the isolates contained a previously reported major deletion but in patients not epidemiologically related to the previously studied cohort.We have developed a simple and accurate method for the characterization and screening of SARS-coronavirus genotypes. It is a promising tool for the study of epidemiological relationships between documented cases during an outbreak.The Severe Acute Respiratory Syndrome (SARS) is a recently emerged infectious disease which led to a global epidemic between 2002 and 2003. A novel coronavirus (SARS-CoV) was identified as the causative agent [1]. The genomic sequence of the SARS-CoV was promptly characterized [2,3]. Thereafter, studies had focused on the early detection of SARS-CoV and the development of diagnostic tools [4-6]. Systematic analysis of the SARS-CoV sequence information have demonstrated that characteristic viral genotypes predominated at certain periods during the course of the outbreak [7-10]. Furthermore, characterization of the viral sequences have been shown to be a useful tool for confirming epidemiological associations between infected individuals as suspected from conventional epidemiological investigations [9-11]. In-depth analysis of the available sequence data on SARS-CoV also revealed that the viral isolates could be readily subclassified into several major genotypes based on nucleotide variations at specific genomic positions [8,12]. In a larg
Absence of association between angiotensin converting enzyme polymorphism and development of adult respiratory distress syndrome in patients with severe acute respiratory syndrome: a case control study
KC Allen Chan, Nelson LS Tang, David SC Hui, Grace TY Chung, Alan KL Wu, Stephen SC Chim, Rossa WK Chiu, Nelson Lee, KW Choi, YM Sung, Paul KS Chan, YK Tong, ST Lai, WC Yu, Owen Tsang, YM Dennis Lo
BMC Infectious Diseases , 2005, DOI: 10.1186/1471-2334-5-26
Abstract: One hundred and forty genetically unrelated Chinese SARS patients and 326 healthy volunteers were recruited. The ACE I/D genotypes were determined by polymerase chain reaction and agarose gel electrophoresis.There is no significant difference in the genotypic distributions and the allelic frequencies of the ACE I/D polymorphism between the SARS patients and the healthy control subjects. Moreover, there is also no evidence that ACE I/D polymorphism is associated with the progression to ARDS or the requirement of intensive care in the SARS patients. In multivariate logistic analysis, age is the only factor associated with the development of ARDS while age and male sex are independent factors associated with the requirement of intensive care.The ACE I/D polymorphism is not directly related to increased susceptibility to SARS-coronavirus infection and is not associated with poor outcomes after SARS-coronavirus infection.The outbreak of the severe acute respiratory syndrome (SARS) has made a great impact to the health care systems around the world. The pandemic affected over 8000 individuals and resulted in 774 deaths worldwide [1]. Several clinical parameters, including male sex [2,3], age of over 60 years [2,3], elevated lactate dehydrogenase activity [2-4], low platelet count [2] and high viral load on presentation [5], have been identified to be predictive of the severity of the disease in affected individuals. Moreover, it has been postulated that genetic variations of the host and the virus may account for the individual difference in the susceptibility to the infection and the severity of the disease. With regard to viral factors, it has been shown that there is no significant difference in the genetic sequences of viruses causing the two major outbreaks in Hong Kong, namely the Prince of Wales Hospital and Amoy Gardens outbreaks, despite the significant difference in the mortality rates and diarrheal rates of the two cohorts [6]. Furthermore, several association
Polymethylmethacrylate bone cements and additives: A review of the literature
Manit Arora,Edward KS Chan,Sunil Gupta,Ashish D Diwan
World Journal of Orthopedics , 2013, DOI: 10.5312/wjo.v4.i2.67
Abstract: Polymethylmethacrylate (PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950s to the recent advent of nanoparticle additives. Additives have been trialed to address problems with modern bone cements such as the loosening of prosthesis, high post-operative infection rates, and inflammatory reduction in interface integrity. This review aims to assess current additives used in PMMA bone cements and offer an insight regarding future directions for this biomaterial. Low index (< 15%) vitamin E and low index (< 5 g) antibiotic impregnated additives significantly address infection and inflammatory problems, with only modest reductions in mechanical strength. Chitosan (15% w/w PMMA) and silver (1% w/w PMMA) nanoparticles have strong antibacterial activity with no significant reduction in mechanical strength. Future work on PMMA bone cements should focus on trialing combinations of these additives as this may enhance favourable properties.
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