No description available.

Thesis (M.P.H.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 90-95).

Background: Isolation of respiratory viruses routinely requires a panel of cell lines. Management of these cell lines is usually considered complex, cumbersome, long turnaround time and high cost. In order to improve the detection rate and cost, there is a need to evaluate any other cell line that could be as sensitive as the routine cell line for the detection of respiratory viruses. The human colon adeno-carcinoma (Caco-2) cell line has been shown to support the growth of enteroviruses, enteric viruses, and influenza A virus, and ability to grow coronavirus NL63 and SARS from culture isolates. In the present study, the isolation rate of respiratory viruses in Caco-2 from clinical specimens was studied and compared with the conventional panel of cell lines for the diagnosis of respiratory virus disease. Material and methods: The study was performed in two stages. In the first stage, one hundred and eighty-nine nasopharyngeal aspirates confirmed positive by direct immunofluorescence were used to inoculate onto Caco-2, and HEp-2, A549, MDCK, LLC-MK2 cell lines at the same time. In the second stage, fifty-six nasopharyngeal aspirates were randomly selected and cultured on Caco-2, HEp-2, A549, MDCK and LLC-MK2. Infected cells were examined daily for cytopathic effect for up to 10 days. Virus was further identified by performing direct immunofluorescence test for detection of eight common respiratory viruses (respiratory syncytial virus, influenza A and B viruses, parainfluenza type 1, 2, 3, 4 viruses and adenovirus). Results: Caco-2 (84%) was found to be the most efficient cell line to propagate the respiratory viruses from nasopharyngeal aspirate when compared with any positive by these conventional panel cells (78%) or individual cell line MDCK (38%), HEp-2 (21%), LLC-MK2 (27%) and A549 (37%). The latter differences were statistically significant (p = <0.000001). Furthermore, Caco-2 recovered 86% (36/42) viruses of conventional panel cells negative samples, while conventional panel cells recovered 80% (24/30) viruses of Caco-2 cells negative samples. Conclusion: Caco-2 is sensitive to a wide range of virus and can greatly simplify routine cell culture service for isolation of respiratory viruses. / published_or_final_version / Microbiology / Master / Master of Medical Sciences

Thesis (doctoral)--University of Tartu, Estonia, 1995. / Vita. Includes bibliographical references.

Abstract available in the Journal of Investigative Medicine.

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 104-112).

Thesis (M.N.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 146-155.

Acute respiratory infections (ARI) are a major global cause of morbidity and mortality. Vitamin D deficiency has been reported to associate with susceptibility to ARI and with greater severity and poorer control of asthma and chronic obstructive pulmonary disease (COPD). Clinical trials of vitamin D for the prevention of ARI have yielded heterogeneous results, with some showing protection and others not. This may reflect variation in the frequency of genetic variants influencing response to vitamin D supplementation in different populations. The impact that genetic variation in the vitamin D pathway has on vitamin D status, disease phenotype and response to vitamin D supplementation in prevention of ARI has not been comprehensively investigated. Methods: I conducted: 1. A systematic review and meta-analysis of clinical studies which have investigated vitamin D as a potential therapy for ARI; 2. Three cross-sectional studies (in n=297 adult asthma patients, n=278 COPD patients, and n=272 older adults) to investigate potential environmental determinants (lifestyle and anthropometric) and genetic determinants (35 single nucleotide polymorphisms [SNP] in 11 vitamin D related genes) of serum 25-hydroxyvitamin D concentration (25[OH]D) and clinical phenotype; 3. Three prospective studies investigating the influence of genetic variation in the vitamin D pathway on a) susceptibility to ARI (main effects analysis) and b) efficacy of vitamin D supplementation for the prevention of ARI (interaction analysis). Results: My systematic review identified consistent reports of an inverse association between vitamin D status and risk of ARI in observational studies, and heterogeneous reports from clinical trials. My cross-sectional studies identified a range of classical environmental factors which predict vitamin D status in the three study populations, but did not identify any genetic variants in the vitamin D pathway that associate with vitamin D status. I identified an association between vitamin D deficiency and decreased lung function in COPD patients, but no associations between vitamin D deficiency and asthma phenotype. Finally, my analysis identified a haplotype of 5 single nucleotide polymorphisms in the vitamin D receptor (VDR) gene which significantly modify the effect of vitamin D supplementation on risk of upper respiratory infection in COPD patients. Conclusions: I identified environmental determinants that predict 25(OH)D concentrations in all three study populations, but only found an association between vitamin D deficiency and disease severity in COPD patients. Furthermore, I identified a haplotype in VDR which modifies the effect of vitamin D supplementation in COPD patients to result in a significantly reduced risk of ARI.

Background The prevention of chronic diseases has always been a major focus in the medical field as a measure to improve public health. As a potential prevention to one of the most common chronic diseases, vitamin D was previously reported to show some signs of positive effect on the prevention of upper respiratory tract infections. Although trials were performed to demonstrate the association between the effectiveness of vitamin D and upper respiratory tract infections in the past few years, the number of randomized controlled trials was limited. Only one systematic review with meta-analysis was carried out to study the effect of vitamin D supplementation on prevention of respiratory tract infections (Charan et al., 2012). Aim A systematic review of the existing evidence was carried out with the aim to examine the effectiveness of vitamin D supplementation as an intervention in prevention of upper respiratory tract infections. Method Studies were selectively chosen based on the inclusion and exclusion criteria. Retrieval of studies was performed and identified from MEDLINE (Ovid) and PUBMED. MeSH terms of “Vitamin D” and “Upper respiratory tract infections” were applied in the search. Only randomized controlled trials were selected. Non-English publications, reviews, discussions, conference papers, and publications with outcomes being not incidence of URTI, were excluded. The quality of each study was evaluated using the Jadad scale (Jadad et al., 1996). Data from the trials was extracted into the meta-analysis, and odds ratios and confidence intervals were used as measures of the association between vitamin D supplementation and incidence of upper respiratory tract infections across studies. Result Five randomized controlled trials were included in this review. In this meta-analysis, the number of events of upper respiratory tract infections in vitamin D group was lower than that in the placebo group (OR=0.53), suggesting that a 47% lower odds of falling in vitamin D groups than in controls. The 95% confidence interval ranged from 0.30to 0.93and did not include 1, suggesting that the effect of vitamin D on prevention of upper respiratory tract infections was significant. However, when the trials were divided into children and adult groups, the results were significantly different. The result of the trials with two children gave an OR of 0.33(95%CI: 0.13, 0.83), meaning a positive effect of vitamin D could be observed in the vitamin D group, compared to the placebo group. Meanwhile, three trials on adults had an OR of 0.78 (95%CI: 0.56, 1.09), which was insufficient to suggest the two groups were different. Conclusion While the positive effect of vitamin D supplementation for the prevention of upper respiratory tract infections is evident on children in this review, it is much less significant on adults due to inconsistencies in the results. Therefore, more research and trials with improved methodologies would be required in the future to increase our understanding and provide more certainty on this matter. / published_or_final_version / Public Health / Master / Master of Public Health