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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.


MCCOMBIE, SUSAN CAROLE. January 1986 (has links)
Viral hepatitis has been a universal human affliction for thousands of years. Only recently has it become understood, and there are still many unanswered questions. This dissertation examines the epidemiology of viral hepatitis in a county in the southwestern United States. An historical review traces the history of concepts of jaundice and details recent advances in the understanding of the transmission of the clinical entities grouped under the heading of viral hepatitis. Age specific incidence rates for all forms of hepatitis in the study population are compared to national rates. Data indicate that the study population experiences higher rates of enteric disease and lower rates of sexually transmitted disease than the nation as a whole. The hypothesis that diseases with similar routes of transmission will be associated with each other and show similar socioeconomic patterns was tested using three year average census tract incidence rates for 1982-84. In almost all samples, hepatitis A and shigellosis are more similar to each other than either is to hepatitis B. A similarity between hepatitis B and syphilis is also evident, but in fewer samples, reflecting their more disparate routes of transmission. Different relationships between incidence rates and socioeconomic variables are evident when the analysis is done using data from the fifty states for 1982. Participant observation as a disease investigator generated information on beliefs about hepatitis among lay and medical personnel. Often these beliefs diverge significantly from accepted facts about hepatitis. These findings have implications for the design of public health programs to control communicable diseases with similar modes of transmission.

Viral diversity and dynamics of hepatitis C virus

Smith, Jennifer January 2011 (has links)
Complex patterns of HCV infection are increasingly reported, particularly in highly exposed individuals, with multiple and variable subtype profiles seen in many chronic patients. This study aims to address some of the questions arising from this increasingly diverse and dynamic picture, both within hosts and at a population level. In Chapter 2 I find evidence for a highly dynamic infection profile in acute HCV, both in terms of viral load and the dominant subtype. I extrapolate these observations from individual patients to formulate a model of HCV transmission across a high-risk population in order to predict the impact of current and anticipated interventions in Chapters 3 and 4. I show that antiviral therapy and a putative vaccination can still have a significant impact on HCV prevalence at the population level, even when the latter offers only partial protection and in the epidemiological background of ongoing exposure. Thus, in an epidemic with more than one circulating strain it will be crucial for any individual or combination of interventions to target all variants present. In Chapter 5 I demonstrate that early viral load kinetics of patients initiating treatment are indicative of treatment outcome. Strain differences are also evident in the virologic response to treatment with hard-to-treat genotype 1 exhibiting a slower rate of viral load decline than genotypes 2 and 3.

Mechanisms of hepatic injury in murine hepatitis virus type 3 infection

MacPhee, Peggy J. January 1989 (has links)
Murine hepatitis virus type 3 (MHV-3), a member of the coronavirus family, induces a response that varies with the age and genetic background of the host mouse strain. A/J mice are fully resistant to the virus, while Balbc/J are fully susceptible and C3HebFe/J are semi-susceptible, making it possible to predictably reproduce the major human responses to hepatitis viruses. Although there has been considerable discussion of viral pathology in the literature, there has been much less emphasis on pathogenesis. In the experiments described here, histological, biophysical, and immunological techniques have been used to define the processes and cells involved. Transmission electron microscopic observations have confirmed that Kupffer and endothelial cells of hepatic sinusoids show clear changes by 12 hrs post-infection (p.i.), which are more advanced than hepatocellular changes. No replicating virus was seen in altered hepatocytes up to 3 days p.i. Scanning electron microscopy demonstrated that areas of necrosis are focal in nature and at 2-3 days p.i. consist of small spherical areas without flow. In vivo microcirculatory studies confirm the localized nature of the lesion and have shown that red cell velocity can be recorded in individual sinusoids . Velocities were found to vary from zero within a lesion to a normal velocity of 69±31 um/sec over a distance of not more than 3 sinusoids. In-vivo microcirculatory studies also revealed the ability of macrophages to move upstream (against flow) in the hepatic sinusoids. Using fluorescein labelled antibodies to cell surface markers (Thy-1, Lyt-2, and L3T4) it was shown that no T-cells of any subset were present in the areas of hepatocellular necrosis. Furthermore, treatment with cyclosporine A, which would be expected to decrease necrosis due to cell mediated cytotoxicity, did not significantly alter the course of the disease. The only cells which increased in number in the liver post infection were cells of the monocyte/macrophage lineage (Mac 1+), which had increased twofold at 12 hrs (p<.025) p.i. and to greater than twenty fold (p<.005) by 3 days p.i. Resistance in the A/J strain did not reflect an inability of the immunocompetent cells to present and respond to viral antigen. It was demonstrated that MHV-3 infected macrophages from resistant A/J mice are better able to stimulate proliferation of allogeneic and syngeneic lymphocytes than those from the sensitive Balb/cJ strain. In contrast, MHV-3 infection caused a significant enhancement of chemiluminescence from Balb/cJ macrophages, which did not occur in A/J animals. In vivo studies demonstrated a significant increase in free radical reaction products, including conjugated dienes (of long chain free fatty acids and aldehydes), thiobarbituric acid reactive substances, and lipid soluble fluorescent products between 12-72 hours p.i. with MHV-3 in the livers of susceptible Balb/cJ strain mice. All of these are products of oxidative cleavage of cellular and membrane polyunsaturated fatty acids, and result from the action of oxygen free radicals. Free radical inhibitors, or quenchers of free radical reaction products, were able to significantly reduce the liver necrosis in the susceptible mouse strain following infection. Radioimmune assays for antibody to MHV-3 have confirmed the presence of preformed antibodies to (or cross-reactive with) MHV-3 in the sera of both susceptible and resistant mice, pre and post-infection. Immunofluorescent labelled antibodies have also been used to demonstrate the presence of IgG deposits in the sinusoids of the liver both pre and post infection. This suggests the possibility that these mice have been infected with a non-virulent MHV strain prior to these experiments. From these studies, we conclude that the hepatic injury caused by MHV-3 infction in Balb/cJ mice is mediated predominantly by fixed and migratory cells of the mononuclear phagocytic series. Susceptibility and resistance are related to strain dependant differences in the response of macrophages (and Kupffer cells) to infection, and include the release of procoagulant activity (previously shown) and reactive oxygen radicals (and possibly other macrophage activation products such as PAF) that act together to induce hepatocellular necrosis. Preformed non-neutralizing antibody and an intact complement cascade may enhance viral uptake and activation of macrophages in the Balbc/J mice. Resistance to necrosis may be enhanced by a genetic deficiency of C5 in the A/J mice, preventing the formation of the membrane attack complex and hence complement dependant cell lysis, or macrophage activation. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Studies on transmission and immune responses of the human hepaciviruses /

Chen, Margaret, January 1900 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 8 uppsatser.

Conformational antigenic determinants of the HEV CAPSID

張紀忠, Zhang, Jizhong. January 2000 (has links)
published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

Studies on the replication of hepadnaviruses and hepatitis delta virus / Tom Bernard Macnaughton.

Macnaughton, Tom Bernard January 1990 (has links)
Copies of author's previously published articles contained in back cover pocket. / Bibliography: leaves 129-152. / xiv, 152, [60] leaves, [28] leaves of plates : ill. (some col.) (some folded) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines hepadravirus and HDV replication and gene expression with particular emphasis on the block(s) preventing HBV infection invitro, the extent of the helper function provided by HDV by HBV and the mechanism of HDV RNA replication. / Thesis (Ph.D.)--University of Adelaide, Depts. of Microbiology and Immunology, 1992

Conformational antigenic determinants of the HEV CAPSID /

Zhang, Jizhong. January 2000 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 150-157).

Studies on the pathogenesis of Hepadnavirus infection

Jilbert, Allison Rae January 1989 (has links)
Improved methods for the in situ hybridisation detection of messenger RNA ( mRNA ) in sections of liver tissue, were derived by use of an experimental system. This involved the use of tritiated-poly ( dT ) probes to detect poly ( A ) sequences attached to the 3 ' end of mRNA in sections of mouse liver that had been processed in various ways. The improved - methods were applied to the detection of hepatitis B virus ( HBV ) - and hepatitis delta virus ( HDV ) - RNA. In situ hybridisation and immunostaining techniques were then applied to studies of the pathogenesis of HBV and duck hepatitis B virus ( DHBV ) infection. In situ hybridisation studies of liver biopsy tissue from HBV - infected immunosuppressed renal transplant patients demonstrated an anatomical association between piecemeal necrosis and HBV replication at the cellular level in some patients. However, widespread replicative infection of hepatocytes also occurred in some patients in the presence of normal hepatocyte morphology and mild inflammatory changes indicating that at the cellular level virus replication was not necessarily a direct cytopathic process. These findings supported the view that hepatocyte Injury may : ( i ) result from immune - mediated damage directed against cells undergoing replicative, but not restricted infection ; ( ii ) eliminate cells undergoing replicative infection and favour clonal regeneration of cells undergoing restricted infection. Localisation of interferon - alpha ( IFN - alpha ) expression in liver tissue chronically infected with HBV and HDV, identified mononuclear cells and fibroblasts ( but not hepatocytes ) as the main producers of IFN - alpha. IFN - alpha - positive cells were associated with areas of liver tissue containing cells supporting virus replication and exhibiting the greatest degree of liver damage, suggesting that locally produced IFN - alpha may be a natural regulator of virus replication in chronic liver disease. Experimental DHBV infection of Pekin - Aylesbury ducks showed that virus inoculated either intravenously or intraperitoneally, gained access to randomly distributed hepatocytes without first replicating in other cell types in the liver. Virus was seen to disseminate to contiguous cells following anatomical boundaries by the third day post - inoculation. Markers of DHBV infection in liver and serum showed reproducible kinetics, and duck hepatocytes in this system appeared to be highly permissive as large amounts of DHBV DNA and DHBsAg were produced intracellularly without the development of ongoing cytopathology. Hepatocytes were the major cell type responsible for early significant DHBV replication, in contrast to pancreas, kidney, spleen and circulating mononuclear cells where significant levels of infection were detected only after the first week of infection and the onset of viraemia. / Thesis (Ph.D.)--Department of Microbiology and Immunology, 1989.

Applied use of radioimmunoassay for detection of viral hepatitis in water samples

Carter, Judy K. 03 June 2011 (has links)
Viral hepatitis is a disease caused by a virus, or a virus-like particle and is extremely infectious. Infection can occur when the virus is present in minute quanities. Outbreaks of this disease have been associated with water supplies contaminated with raw sewage. Detection of viral hepatitis in water samples, at present, consists of testing the serum of persons who have contracted the disease after consuming water suspected of containing hepatitis virus. Since this method of determination is time consuming and subjective, an alternative method of detecting the presence of hepatitis virus in water was explored in this research.Radioim munoassay (RIA), used for the detection of Australia antigen (HAA) in the serum of humans, utilizes a tagging system in which Australia antigen antibody is bound with iodine-125. This technique, a combination of chemistry and immunology, can detect less than one- billionth of a gram of HAA in serum and requires approximately four hours to complete the testing. RIA detection of HAA is presently limited to detection of HAA in serum samples.This research used RIA as a detection system to test water samples collected from local water sources. Control serum samples collected from a local hospital were tested for HAA. Fifteen water samples and two serum samples tested were positive upon initial testing for Australia antigen. HAA was also detected in water samples in control situations in which sera with a high titer to HAA were diluted in water and then tested using RIA.Ball State UniversityMuncie, IN 47306

The application of DNA hybridisation methods to a determination of the association of hepatitis B virus with cirrhosis and hepatoma.

Nair, Shamila. January 1987 (has links)
Autopsy liver material from patients having died of chronic liver disease, cirrhosis, hepatocellular carcinoma (HCC) and causes unrelated to liver diseases was examined by dot blot hybridisation for the presence of HBV DNA. The results indicate that of the patients with chronic liver disease 6/9 were positive for HBV DNA in the liver tissue; of the patients with HCC 3/4 were positive for HBV DNA; of the patients with cirrhosis 4/4 showed the presence of HBV DNA in the liver. Thus by this technique 13/17 (76%) of these patients, all of whom were HBsAg positive, were shown to have HBV DNA present in liver tissue. However, autopsy liver samples were found to be unsuitable for Southern blot hybridisation. Biopsy liver/tumour tissue was examined for the presence of integrated or non-integrated HBV DNA by Southern blot analysis using the enzymes Eco R1 and Hind 111. 5/5 patients who were both HBsAg and HBeAg positive had extrachromosomal HBV DNA and 2/5 also showed the presence of integrated HBV DNA. 3/4 patients who were HBsAg positive and HBeAg negative had extrachromosomal HBV DNA and all three also had integrated HBV DNA. One control patient was negative for both markers and also for Southern blot hybridisation with the HBV DNA probe. These results support the hypothesis that HBV is a factor in the development of HCC, and indicate that the dot blot hybridisation method would be suitable for routine evaluation of patients with chronic liver disease or cirrhosis. / Thesis (M. Med.)-University of Natal, Durban, 1987.

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