Peter C S Tsang

Peter C S Tsang
The University of Hong Kong | HKU

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53
Publications
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Publications

Publications (53)
Article
Full-text available
Background: The antibiotic lock technique (ALT) has been recommended for the prevention and treatment of catheter-related candidaemia. Biofilms of Candida species are resistant to some of the antifungal agents currently used. Aspirin has been shown to have anti-fungal effect but its effect on candidal biofilm is poorly understood. Purpose: The a...
Article
Full-text available
Titanium and its alloys are widely used in biomedical devices, e.g. implants, due to its biocompatibility and osseointegration ability. In fact, fungal (Candida spp.) infection has been identified as one of the key reasons causing the failure of the device that is inevitable and impactful to the society. Thus, this study evaluated the surface morph...
Article
Introduction: Candida albicans possesses the ability to switch rapidly between yeast to hyphal forms. Hyphal formation is a remarkable pathogenic characteristic, which allows C. albicans to invade into host cells. Objectives: This study was to investigate the role of the C. albicans SAP9 gene in hyphal formation and invasion ability. Methods:...
Conference Paper
Objective: To investigate the effect of C. albicans SAP7 gene in induced endocytosis in Candida-epithelial cell interactions Method: In this study, C. albicans sap7 mutant strain was constructed in our laboratory by a PCR – based gene disruption method. In the endocytosis assay, the number of C. albicans cells that were cell-associated with and e...
Article
AimThe aim of the present study was to compare the effectiveness of DNA extraction using an extraction kit against the standard boiling technique for the detection of Epstein–Barr virus (EBV) DNA in nasopharyngeal carcinoma (NPC) patients. Methods Stimulated whole saliva samples from newly-diagnosed NPC patients were collected. EBV DNA was extracte...
Conference Paper
Objective: To investigate the in vitro effect of purpurin on biofilm development of non-albicans Candida fungi Method: Biofilms of five non-albicans Candida fungi (C. glabrata ATCC 90030, C. tropicalis ATCC 13803, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, C. dubliniensis MYA-646) were prepared in pre-sterilized, polystyrene, flat-botto...
Conference Paper
Objective: The purpose of this study was to investigate the antibacterial effect of Er,Cr:YSGG laser on Fusobacterium nucleatum and Streptococcus sanguinis adhered on zirconia surface in vitro Method: Biofilms of F. nucleatum and S. sanguinis were grown on zirconia discs and irradiated with Er,Cr:YSGG laser (λ= 2780 nm) at 1W. The number of viable...
Conference Paper
Objective: To investigate the in vitro effect of melatonin on C. parapsilosis biofilms Method: C. parapsilosis ATCC 22019 was grown on YPD agar (1% yeast extract, 2% peptone, 2% dextrose, 2% agar) at 30°C overnight. Fungal cells were harvested, washed twice with PBS, and finally resuspended in yeast nitrogen base (YNB) medium at 107 cells/mL...
Conference Paper
Objectives: To determine the adhesion of bacteria on zirconia with different surface treatments and to determine the effect of Er,Cr:YSGG laser on bacteria adhered on zirconia with different surface treatments. Methods: Zirconia blocks were cut into discs which were subsequently polished, sonicated and sintered. The sintered discs were randomly d...
Article
Aim: Highly active antiretroviral therapy (HAART) has altered the prevalence and incidence of oral mucosal lesions of HIV infection. Recent reports show a variation in the prevalence of oral mucosal lesions in different population groups. Understanding the prevalence of these lesions is of paramount importance in the efficient delivery of dental ca...
Conference Paper
Objectives: To investigate the in vitro effects of purpurin on Candida albicans hyphal development and biofilm formation. Methods: C. albicans SC 5314 biofilms were prepared in polystyrene, flat bottom 96-well microtiter plates. The cell suspension (100 l, 107cells/ml in YNB) was transferred to the wells and incubated at 37oC, 75 rpm for 1.5 h. A...
Conference Paper
Candida biofilms on central venous catheters are one of the commonest nosocomial fungal bloodstream infections. Antifungal lock solutions have been shown to be effective in salvaging indwelling catheters in patients requiring intravenous therapy. Objectives: To determine the activity of aspirin as a lock solution against four Candida biofilms on si...
Article
Nasopharyngeal carcinoma (NPC) is a solid tumor closely associated with Epstein-Barr virus (EBV) infection. The purpose of this investigation was to detect and quantify the EBV DNA level in salivary samples of NPC patients following treatment using real-time PCR. A total of 175 consecutive newly diagnosed NPC patients' whole saliva samples were col...
Article
Epstein Barr virus (EBV) is one of the ubiquitous viral carcinogens found in humans and successfully infects more than 90% of the world population. The spectrum of EBV-related pathology ranges from asymptomatic primary infection to grave B- and T-cell malignancies. EBV triggers lymphoproliferative disorders after allogeneic stem cell transplantatio...
Conference Paper
The mortality and morbidity of HIV-infected patients have declined with the advent of highly active antiretroviral therapy (HAART). However, its effect on Candida infections remains inconclusive. Objectives: To determine the phospholipase, proteinase and haemoltyic activities of oral C. albicans in HIV-infected patients on HAART, and the factors af...
Conference Paper
Human immunodeficiency virus(HIV) infection can dysregulate cytokine signaling which may influence the replication of opportunistic viruses that persist in tissues and biological fluids. Epstein-barr virus(EBV) is one such pathogen that trigger lympho-proliferative malignant conditions during HIV infection. Objectives: To compare oral cytokine in...
Article
Full-text available
The ubiquitous cytokine transforming growth factor-beta1 (TGF-beta1) is one of the most potent metastatic inducers. Functional interactomic mapping using high-throughput proteomic and genomic data provides valuable insights into the regulation of tumor suppressive and metastatic attributes of TGF-beta1. Polarity changes of the TGF-beta1 interactome...
Article
The use of highly active antiretroviral therapy (HAART) in the management of human immunodeficiency virus (HIV) restores immune responses against pathogens and has greatly decreased mortality. However, in about 25% to 35% of patients receiving HAART, the reconstituted immune system leads to a pathological inflammatory response, commonly known as im...
Article
Although persister cells in Candida albicans biofilm may contribute to its increased resistance to antifungal drugs, little information is available on the formation of Candida persister cells on titanium surfaces. The effect of different surface treatments of Ti on persister cells was determined in the present study. Titanium discs were surface-tr...
Article
Highly active antiretroviral therapy (HAART), using HIV protease inhibitors, is commonly used in the management of HIV infection. HIV protease inhibitors also have a direct effect on a key virulence factor of Candida albicans, its secreted aspartyl proteinase (Sap). Although protease inhibitors can attenuate Candida adhesion to human epithelial cel...
Conference Paper
Highly active anti-retroviral therapy (HAART) has revolutionized the prognostic outcome of patients infected with human immunodeficiency virus (HIV). However, recent reports suggest oral shedding of Epstein barr virus(EBV), which is an oncogenic herpes virus,is significantly higher in the HAART era. Human cytokine profiles are often altered to faci...
Article
To study oral health conditions, diabetic medical complications and their association in type 2 diabetes mellitus (DM). Cross-sectional survey of 364 type 2 DM patients (63.6 +/- 10.1 years, 54% female) and 161 controls (64.1 +/- 10.6 years, 53% female) with or without essential hypertension, predominantly low-income, attending a hospital were recr...
Article
Although it is well known that fungal biofilms have increased resistance to antimicrobial agents, limited information is available on the formation of candidal biofilms on implant surfaces with different surface roughness and their resistance to conventional antifungal therapy. In the current study, the effect of increasing the surface roughness of...
Article
Full-text available
The aim of this study was to biotype and characterize phospholipase, proteinase and haemolytic activities of oral Candida albicans isolates from 210 Chinese patients with type 2 diabetes mellitus (DM) and 210 age- and sex-matched healthy controls. Seventy-six and 50 C. albicans isolates were obtained from type 2 DM patients and controls, respective...
Article
To assess the knowledge of and attitudes toward severe acute respiratory syndrome (SARS) among patients attending a teaching dental hospital and private dental practices in Hong Kong during a major local SARS outbreak. 250 dental patients were interviewed by questionnaire and 213 were interviewed by phone. Less than one-third (30.0%) of the 463 res...
Article
A comparison was made of Oral Balance gel delivered by slow release via a novel intra-oral device versus an oral bolus of gel on the oral health condition and oral health-related quality of life (OHRQoL) in patients who had received standard head and neck irradiation for nasopharyngeal carcinoma. Twenty-two participants took part in a randomized si...
Article
The study was aimed at comparing the efficacy of disinfection of root canals with periapical radiolucencies when treated with either antibiotics/steroid medicaments (Ledermix or Septomixine) or a calcium hydroxide paste (Calasept). Microbiological samples were taken before and after two-visit endodontic treatment from 88 canals with apical periodon...
Article
This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and convention...
Article
The poor sensitivity of phenotypic identification techniques has hampered the taxonomic differentiation of Actinomyces. Hence we developed a sensitive and specific, PCR-based oligonucleotide-DNA hybridization technique to detect Actinomyces spp. and, used this method to detect these organisms in samples directly obtained from infected root canals....
Article
Renal transplant patients undergoing immunosuppressive therapy may experience periodontal side-effects such as gingival overgrowth. This study evaluated the subgingival microbiota of renal transplant recipients with or without periodontal tissue destruction who may have concurrent gingival enlargement. Subgingival paper point samples taken from the...
Article
The increased frequency and severity of candidal infections in human immunodeficiency virus (HIV)-infected individuals has prompted the wide use of antifungals, such as amphotericin B, ketoconazole, and fluconazole, resulting in the emergence of drug-resistant strains of Candida albicans. To study this phenomenon in an ethnic Chinese cohort, we iso...
Article
Although clinically distinctive types of periodontal disease are known to be associated with HIV infection, the pathogenesis remains unclear. In the present study, the subgingival microflora of 21 HIV-infected and 11 HIV-free ethnic Chinese were studied using the direct microscopic and anaerobic culture methods. Motile curved rods were found to be...
Article
To determine the oral health status, oral microflora and the effect of non-surgical periodontal treatment on gingival overgrowth of renal allograft recipients receiving either cyclosporin A (CsA) or FK506 (Tacrolimus) as an immunosuppressant. A total of 47 patients receiving CsA (mean age 43.1 years) and 10 receiving FK506 (mean age 40.1 years) wer...
Article
The objective was to determine the oral carriage patterns of yeasts and coliforms and their relationships, if any, with age, risk group, CDC classification, CD4+ count and medications in a predominantly Chinese, HIV-infected cohort in Hong Kong. A prospective longitudinal study was carried out over a 12-month period, of 32 predominantly Chinese mal...
Article
Adherence to host surfaces is an essential prerequisite for colonization and infection. We compared the adherence of 15 oral isolates of Candida albicans harvested from human immunodeficiency virus (HIV)-infected individuals and 12 isolates from HIV-free individuals to buccal epithelial cells (BECs) from HIV-free individuals, and the adherence of a...
Article
To evaluate the salivary lysozyme concentration, flow rate and pH of a predominantly Chinese, HIV-infected group in Hong Kong, and to compare with an equal number of age and gender-matched HIV-free individuals. A prospective longitudinal study over a 12-month period of 32 predominantly Chinese, male, HIV-infected group in a hospital setting in Hong...
Article
A total of 32 HIV-infected, predominantly ethnic Chinese individuals from Hong Kong were examined for oral mucosal lesions over a period of 1 year. The commonest oral lesion found was minor aphthous ulceration (27.4%), while xerostomia (17.8%), ulceration NOS (not otherwise specified; 12.3%), hairy leukoplakia (11.0%) and erythematous candidiasis (...
Article
Oral Candida albicans isolates from HIV-infected individuals in Hong Kong, Australia, Germany and England were characterised using a biotyping system based on enzyme profiles, carbohydrate assimilation patterns and boric acid resistance of the yeasts. A total of 44 biotypes were found amongst the 117 oral C. albicans isolates examined. The major bi...
Conference Paper
HIV transmission occurs on mucosal surfaces of the gastrointestinal and cervicovaginal tracts. Recent clinical trials using chemokines such as CCL5, as mucosal entry inhibitors show great promise. A combination of several chemokines can be useful to prevent transmission of HIV at mucosal sites. The challenge is to decide which of the wide array of...
Conference Paper
Although the use of highly active antiretroviral therapy has reduced the morbidity and mortality in HIV-infected patients, its effect on Candida infection is still poorly understood. Objectives: To determine the phospholipase, proteinase and haemolytic activities of oral Candida albicans isolated from Chinese patients on HAART, and to investigate t...

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Project (1)
Project
Problem-based learning (PBL) is adapting to 21st Century learners through the introduction of educational technologies. Research in this field remains limited in scope and scale. The application of an Interactional Ethnography (IE) across three undergraduate PBL healthcare programmes will address both issues. *Funded by The Research Grants Council of Hong Kong, General Research Fund (GRF) Ref. 17100414.