Publications by authors named "Raymond Tsang"

The fim genes which code for the fimbria protective antigens present in both the inactivated whole-cell and acellular vaccines were analyzed in 86 Canadian Bordetella pertussis isolates. At least one of the novel mutations identified was found to involve a surface epitope that has been mapped by serum antibodies from infected or vaccinated subjects.

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Guillain-Barre syndrome is a postinfectious disorder caused by an aberrant immune response to an infectious pathogen, resulting in an autoimmune disease. As with other autoimmune diseases of infectious nature, the intricate balance of the numerous factors involved in the immune response may determine the outcome of the interaction between the microbe and host. Recent studies focusing on the role of cytokines and its network of related mediators and receptors suggest that any imbalance may make a significant contribution to the outcome of the infectious disease process.

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Isolates of the hypervirulent Neisseria meningitidis clone ET-15 found to express the serogroup B antigen were investigated and compared with representative members of serogroup B and C isolates. Clonal-clustering methods clearly grouped the B:ET15 isolates with C:ET15 isolates, indicating the only major difference between the two groups was in the capsule expressed. The organization of the cps operon from the B:ET15 isolates was found to be consistent with typical serogroup B isolates and differed from serogroup C isolates only in the sialyl transferase gene present.

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Background: IgA antibody titers to the Epstein-Barr virus (EBV) viral capsid antigen (EBV IgA-VCA) and to the EBV early antigen (EBV IgA-EA) are used to screen for nasopharyngeal carcinoma (NPC). This study evaluates the sensitivity and specificity of EBV IgA-VCA and EBV IgA-EA titers in screening patients for NPC and in those diagnosed with NPC at our institution.

Methods: The NPC status was determined for all patients who had their EBV IgA-VCA and EBV-IgA EA titers measured over a 3-year period, and the sensitivity and specificity were calculated.

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The nucleotide sequences of the PorB proteins from 28 nonserotypeable serogroup C ET-15 meningococci recovered from invasive meningococcal disease cases were determined. PCR amplification of the porB genes responsible for encoding the serotype antigen was used for DNA sequence determination and identification of the nature of the serotype antigen. DNA sequencing revealed that three strains were of serotype 2a, and of the remaining 25 strains, 20 were found to have an identical single point mutation in the region of the VR3 gene, which encodes surface-exposed loop VI, where the serotype 2a epitope resides.

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Serogroup C Neisseria meningitidis belonging to the electrophoretic type (ET) ET-15, a variant of ET-37, is endemic in Canada. Like other serogroup C ET-37 meningococci, the endemic ET-15 strains are usually found to carry the serotype and serosubtype antigens of 2a:P1.5,2.

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Objectives/hypothesis: The objective was to describe the impact of severe acute respiratory syndrome (SARS) on the services of the division of otorhinolaryngology-head and neck surgery at an academic tertiary referral hospital in Hong Kong.

Study Design: Descriptive.

Methods: Records of general and subspecialty outpatient attendance, ward admissions, ward bed occupancy, and elective and emergency surgery were obtained for the period since the SARS outbreak and for an equivalent period before the outbreak.

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We describe an outbreak, in a community of men who have sex with men, of serogroup C meningococcal disease caused by a genetic variant of the serotype 2a ET-15 Neisseria meningitidis characterized by a point mutation in the gene coding for the serotype 2a antigen. A microbiological characterization of the outbreak strain is presented in this report.

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Objective: We undertook a prospective study of the efficacy of a new intranasal steroid, mometasone furoate nasal spray (Nasonex; Schering-Plough Corp, Kenilworth, NJ).

Study Design: Chinese patients with allergic rhinitis were recruited. The patients were assessed by a questionnaire that included demographic data and a Rhinitis Symptoms Score.

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The gene encoding the outer membrane adhesin/invasin protein OpcA was previously described in the genomes of two pathogenic Neisseria species, N. meningitidis (Nm) and N. gonorrhoeae (Ng).

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The interaction between the HPV (human papilloma virus) 16 E7 and other cell growth factors, such as p53 and NFkappaB in laryngeal cancer is not clearly understood. The aim of this study was to examine the expression of these three proteins in tumor and non-tumor laryngeal tissues from patients with laryngeal squamous cell carcinoma. These three proteins were dominantly expressed in the nucleus and their levels were higher in the tumor tissue than in the non-tumor tissue, although the comparison between the tumor and non-tumor tissues of p53 staining did not reach significance.

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Neisseria meningitidis is the causative agent of meningococcal sepsis and meningitis. Neisseria polysaccharea is a nonpathogenic species. N.

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Purpose: Nasopharyngeal carcinoma (NPC) is highly prevalent in southern China and characterized by a strong association with EBV. We aimed to detect EBV DNA and cancer-related gene promoter hypermethylation in nasopharyngeal (NP) brushing samples and provide a novel noninvasive approach for NPC detection.

Experimental Design: Twenty-eight NPC cases and 26 noncancerous subjects were prospectively recruited.

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Lipooligosaccharide (LOS) is a major virulence factor of the pathogenic Neisseria. Nine lgt genes at three chromosomal loci (lgt-1, 2, 3) encoding the glycosyltransferases responsible for the biosynthesis of LOS oligosaccharide chains were examined in 26 Neisseria meningitidis, 51 Neisseria gonorrhoeae and 18 commensal Neisseria strains. DNA hybridization, PCR and nucleotide sequence data were compared to previously reported lgt genes.

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Campylobacter jejuni is recognized as the most common infectious agent associated with the development of Guillain-Barré syndrome. Available information on the complete genome sequence of C. jejuni NCTC 11168 has helped researchers to identify polysaccharide capsules as well as genetic mechanisms in the synthesis of ganglioside-like cell surface molecules in this bacteria.

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