by Yip Chi Wai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 94-113). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstract in Chinese.

No description available.

Mycobacterial infections are responsible for some of the most well known disease, including Tuberculosis. Reported cases of infections caused by mycobacteria that are becoming increasingly resistant to traditional antibiotics are on the increase. This calls for a new approach in developing new drugs that can act on novel antimicrobial targets. One such alternative involves the use of bacteriophages and the study of how they interact with their hosts. Their diversity also suggests that there are many different phage-host interactions acting on multiple targets that are currently still unknown. Eight phages were isolated and characterized. Genomic libraries were constructed on four of these phages and screened for antimicrobial activities using Rhodococcus erythropolis. Six clones were further analyzed, and 15 ORFs were predicted with 8 ORFs being assigned functions. These genes with similarity to proteins in the database suggest that they are involved in membrane integrity and DNA metabolism. These clones were further tested on Saccharomyces cerevisiae to determine whether they have any effects on eukaryotes. The lack of inhibition in S. cerevisiae suggests these phage products are confined to act only in bacteria after millions of years of co-evolution with their host counterparts, and further studies into these genes will continue to shed light on bacterial genomics.

La tuberculosis es una enfermedad infecciosa que constituye un grave problema de salud pública a nivel mundial principalmente en países en vías de desarrollo, como el Perú. Las limitaciones de los métodos clásicos de diagnostico (baciloscopía y cultivo) así como la alta frecuencia de ésta enfermedad han creado la necesidad de implementar nuevas estrategias para incrementar la sensibilidad de las pruebas y a su vez reducir el tiempo necesario para establecer el diagnostico confirmatorio. Considerando que los estudios correspondientes a la región del Tracto Respiratorio Inferior (TRI) son escasos, el objetivo de esta tesis fue determinar el perfil molecular de Mycobacterium tuberculosis en muestras biológicas del TRI de pacientes limeños con sospecha de tuberculosis. En el presente trabajo se evaluaron 43 muestras de pacientes limeños con sospecha clínica de tuberculosis las cuales fueron obtenidas a través de lavado bronquial, aspirado bronquial, secreción bronquial, lavado bronco-alveolar, aspirado bronco-alveolar y broncofibroscopía. De estas muestras se extrajo DNA y se realizó la prueba del PCR - Nested, para ello se empleó como secuencia diana el gen de la proteína A (65KDa) de Mycobacterium tuberculosis, los productos amplificados fueron evidenciados mediante electroforesis en gel de agarosa y tinción con bromuro de etidio. Los resultados obtenidos muestran que el 77% de las muestras procesadas poseen DNA de Mycobacterium tuberculosis, demostrándose la alta sensibilidad y especificidad del método empleado, el 82% de estas muestras correspondieron a la región del árbol bronquial superior, debido a que esta región es el punto de partida para la diseminación de esta micobacteria hacia otras regiones del tracto respiratorio y además, a que la mayoría de muestras fueron tomadas directamente de esta región. Asimismo, la aplicación de la prueba PCR- Nested incrementó la sensibilidad de detección 5.5 veces con respecto a un único evento de amplificación, lo cual demuestra la utilidad de esta prueba en el análisis de material biológico con baja carga micobacteriana como las empleadas en este trabajo. Finalmente, se concluye que la prueba PCR- Nested es un método altamente sensible y específico para detectar DNA de Mycobacterium tuberculosis a partir de muestras procedentes del TRI. / Tuberculosis is an infectious disease that constitutes a serious public health problem worldwide, mainly in developing countries such as Peru. The limitations of the traditional methods of diagnosis (smear and culture) as well as the high incidence of this disease have created the need to implement new strategies to increase the sensitivity of tests to reduce time to establish a confirmed diagnosis. Since there are not many researches at the region of the Lower Respiratory Tract (LRT), the objective of this study was to determine the molecular profile of Mycobacterium tuberculosis in biological samples taken from the LRT of patients with suspicion tuberculosis. In the present study, 43 samples from patients with clinical suspicion of tuberculosis were evaluated. The samples were obtained through bronchial lavage, bronchial aspirate, bronchial secretions, bronco-alveolar lavage, and sucked bronco-alveolar broncofibroscopy. DNA extraction was prepared from each sample, and it was used in a PCR- Nested test targeting the gene encoding the protein A (65KDa) from M. tuberculosis. The results showed that DNA from M. tuberculosis was detected in 77% of the processed samples, revealing a high sensitivity and specificity of this method. From the positive samples, 82% corresponded to those obtained from the bronchial tree top region. This last result is explained because of the fact that most of the samples were taken directly from this region, which is the starting point for the mycobacteria dissemination toward other regions of the respiratory tract. In addition, the application of the PCR-Nested test increased the sensitivity of detection by 5.5 fold compared to a single event amplification, demonstrating the usefulness of this test in the analysis of biological material with low mycobacterial load as those used in this work. Finally, we conclude that the PCR-Nested test is a highly sensitive and specific method for detecting DNA from Mycobacterium tuberculosis in samples from the LRT.

Zugl.: Giessen, Universiẗat, Diss., 2009.

Reproduction de : Thèse d'exercice : Médecine vétérinaire : Toulouse 3 : 2008. / Titre provenant de l'écran titre. Bibliogr. p. 141-157.

Thesis (M. Med. Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 50-57).

Thesis (M.Med.Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 39-49).

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 90-116). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 90-116). Also available in print.