Seed piece to plant transmission of the potato late blight pathogen, Phytophthora infestans, occurred with isolates of the clonal lineages US-8 in Oregon and US-11 in Washington in field trials. Average transmission rate across potato cultivars was 0.5 and 2.4% with US-8, and 0.8 and 1.0% with US-11 in 1999 and 2000, respectively. Transmission rate with US-8 was 2.3% for Russet Burbank (RB) in 1999 and 1.7, 0.7, 4.3, 7.6 and 0.5% for Bannock, Bzura, Ranger, Russet Norkotah (RN), and Umatilla, respectively, in 2000. Transmission rate with US-11 in 1999 was 0.5, 4.9 and 1.4% for RB, RN, and Shepody, respectively, and 1.7% for RB in 2000. Seedborne inoculum of both clonal lineages significantly affected stand establishment and plant vigor. With US-8, final emergence, emergence rate, and aerial biomass of cvs Kennebec, RB, RN, and Shepody were significantly lower than Bzura in 1999, whereas in 2000, these same responses in Chieftain, Bannock, Ranger, and Shepody were significantly lower than Bzura, Umatilla and RN. With US-11, these same response variables were significantly lower in Kennebec, RN and Shepody compared to Bzura and RB in 1999, and were significantly lower in Bannock, Chieftain, Ranger and Shepody compared to RB and Umatilla in 2000. Plant growth responses of cvs RB and RN grown from seed pieces infected with US-8 or US-11 were evaluated in greenhouse trials. RN was equally susceptible to both clonal lineages whereas RB was more resistant than RN to seedborne inoculum of US-11. Compared to RN its final emergence was higher, emergence rate was faster, aerial biomass was greater, and seed piece decay was lower. US-8 was more aggressive than US-11 on RB. US-8 caused a greater reduction in final emergence, emergence rate, and aerial biomass, and a greater increase in seed piece decay. The two clonal lineages were similar in their aggressiveness on RN. This is the first report of cultivar*clonal lineage*inoculum density interactions for plant growth responses of potato grown from seed pieces infected with P. infestans. / Graduation date: 2002

The objectives of this study were: (1) to determine the etiology of bull's eye rot on pears grown in Oregon and Washington; (2) to determine periods of greatest susceptibility of pear wood to canker formation by the fungal pathogens Neofabraea alba and N.perennans; (3) to monitor conidial production in cankers; (4) to determine the timing of fruit infection; and (5) to determine the effect of environmental factors, cultural practices and chemical treatments on the development of bull's eye rot of pears. N. alba, N. perennans and N. sp. nova were identified in isolates obtained from bull's eye rot on pear fruit, using species-specific primers in a PCR reaction. N. alba was also found to be associated with naturally occurring small cankers and pruning stubs on pear trees. Pear trees were inoculated at monthly intervals with mycelia of N. alba and N. perennans to determine susceptibility to canker formation. Susceptibility was highest during autumn and winter months, with larger cankers bearing conspicuous acervuli produced after inoculations from October to February. Small cankers resulted from conidial inoculations with N. perennans on superficially wounded pear branches. Cankers induced after mycelial inoculations sporulated throughout the year with highest amounts of conidia produced from September to December. Pear fruit became naturally infected throughout the growing season, with increasing infection levels close to harvest. Contradictory effects of temperature on bull's eye rot development by N. perennans were observed between 2001 and 2002, where the highest levels of disease were found at 10°C and at 30°C, respectively. Wetness duration did not affect bull's eye rot development, while the concentration of conidia correlated positively with disease development. Over-tree irrigation and late harvest resulted in higher disease levels than under-tree irrigation and early to mid season harvest. The fungicides trifloxystrobin and ziram protected inoculated fruit for about one month, while copper sulfate reduced the sporulation rate of cankers induced by N alba. Thiabendazole applied as a postharvest dip reduced bull's eye rot on inoculated pears. / Graduation date: 2004

Coronary Heart Disease (CHD) accounts for almost 20% of all deaths in the United States and is a leading cause of premature death and disability. The cost for this disease includes not only lost work years, but billions of health care dollars. Women account for almost half of the deaths from CHD and rates for the death of young women have risen 30% from 1988 to 1998. For the two-thirds of women who survive the initial coronary event, the risk of future events and disability increases. Cardiac rehabilitation (CR) is a multi-disciplinary program designed to reduce this risk. Unfortunately, only 25% of eligible women attend the program. Few studies have analyzed the factors that influence women's CR enrollment choices making a careful examination of these factors particularly relevant. The purpose of this study was to qualitatively explore the factors associated with a woman's decision to enroll, or not enroll, in CR from the perspectives of the patient and her support person. Twenty-five women (15 enrolled in CR, 10 not enrolled in CR) and 24 matched support persons (one person's supporters refused to participate) were interviewed using a semi-structured format from September, 1999 to January, 2001. Questions addressed the beliefs, affect, social referents, past experiences/habits, and facilitating/constraining conditions related to CR enrollment choices. Support persons were asked to respond to these questions from their perception of their loved one's attitudes, beliefs and health care seeking behaviors. Information from the interviews was transcribed verbatim, entered into NUD*IST, and coded using the components of the Expanded Theory of Reasoned Action (Triandis, 1977) as a framework. Descriptive analyses was done on basic demographic information, including perceptions of health and depression. There were specific factors identified in each of the primary categories of affect, beliefs, facilitating/constraining factors, and social referents and information. The key findings indicated that a lack of information on CR, feelings related to the perceived necessity of CR, transportation, finances, and accessibility were primary factors in enrollment behavior. Overall agreement between the cardiac female and her support person existed in most categories, except affect, where a minimum number of emotions was stated by the supporter. Cardiologists are a preferred source for CR information and they and primary care physicians need to increase the amount of positive support they provide to post-coronary event women. Emphasis on the necessity of attending CR as well as solutions for transportation and finances may increase enrollment. More research should be completed on the context of depression related to CR, importance of factors identified as having an impact on CR decision making, and the role of support persons in the enrollment choices of women. / Graduation date: 2002

In broiler operations, various health problems develop during the final two weeks of the growing period, resulting in increased mortality and condemnation losses. At this stage, sickly birds were found to be systemically infected by various bacteria regardless of varied clinical signs. The main objective of the present study was to determine the prevalence and nature of systemic bacterial infections in unthrifty commercial broiler chickens and to establish a reproducible infection model in the laboratory. Thirty-one unthrifty 6-week-old broilers were obtained from three farms, and bacterial isolations were conducted on blood, liver, and hock joint. Bacteria were isolated from 87, 90, and 71% of the blood, liver and hock joint samples, respectively. Mean bacterial counts (log������ CFU/ml or g) of the blood and liver were 2.15 and 2.93, respectively. Among 132 bacterial isolates, major species were; Staphylococcus (60%), Corynebacterium (18%), Escherichia coli (5%), and Stomatococcus (4%). Among 79 Staphylococcus isolates, 77 were coagulase-negative. Major species of staphylococci were; S. lentus (19%), S. simulans (18%), S. cohnii (13%), S. gallinarum (10%) and S. captis (7%). In addition, 6 species of gram-positive and 5 species of gram-negative organisms were isolated. Apparently systemic infections were not caused by predominant pathogenic bacterial species, and adequately described as mixed infections. However, there were some significant relationships between isolated bacterial species and sampling sites, suggesting that certain organisms were abundant in the environment of a particular poultry house. These results indicate that systemic infections in market age broilers are caused by mixed bacterial species and suggest that they are caused by suppressed host antibacterial systems rather than pathogenic factors of microorganisms. Antibiotic susceptibility results showed 100% susceptibility of staphylococcal isolates (n=69) against vancomycin and enrofloxacin. Of these coagulase negative staphylococci showed 19% and 73% resistance against methicillin and penicillin G, respectively. There was also heterogeneity in antibiogram profiles within species of coagulase-negative staphylococci. Pathogenicity of representative field isolates from the above described study was tested in 5-day-old embryonated eggs and in 3- week-old broiler chicks. Consistent lethality was demonstrated with S. aureus in embryos. Staphylococcus intermedius or S. lentus demonstrated some pathogenicity, while S. gallinarum or Corynebacterium were non-pathogenic in embryos. In 3-week-old broilers, however, only S. aureus caused septicemia and death; other bacterial species mentioned above caused neither clinical signs of acute or chronic staphylococcosis nor mortality. / Graduation date: 1998

Graduation date: 1997

Monoclonal antibodies were developed against USDA challenge strain of infectious laryngotracheitis virus (ILTV). Indirect immunofluorescence test was used to detect antibodies in supernatants of hybridomas. Hybridoma cells were developed by fusing Sp 2/0 myeloma cells with spleen cells obtained from mice immunized four times with partially purified USDA challenge strain of infectious laryngotracheitis virus. The supernatant of three hybridomas, designated as 2D1D8, 2E11G2, 2C6C7 were found positive for antibody activity against USDA challenge strain of ILTV. Hybridomas producing antibodies were cloned by the limiting dilution method. All three monoclonal antibodies reacted with USDA challenge strain of ILTV, S 88 00224 strain of ILTV, and 86 1169 strain of ILTV in an indirect immunofluorescence test. None of the monoclonal antibodies reacted with avian adenovirus 301 or parrot herpes virus in an indirect immunofluorescence test. The monoclonal antibodies were isotyped, and all three monoclonal antibodies were found to be IgM. / Graduation date: 1993

The gastric pathogen Helicobacter pylori infects more than half of the population worldwide. H. pylori manage to establish persistent infection, which would be life-long if not treated. In order to establish such an infection, this pathogen has to deal with the host immune system. H. pylori has certain characteristics which make the bacteria less announced to the host immune system. Additionally, for remaining in the harsh and acidic environment of the stomach with peristaltic movements and a high frequency of turnover of epithelial cells, H. pylori has developed different binding modes to structures present both in the mucus and on the surface of gastric cells and also to extracellular matrix proteins. Evidently, adhesion has a determinant role for a successful colonization by H. pylori. It has been shown that a small fraction of the H. pylori infection is in intimate contact and attached to the host epithelium. Despite its small proportion, this group maintains the persistency of infection. As there is no suitable in vitro system to mimic the human stomach for studies of H. pylori infection, we have developed the In Vitro Explant Culture technique (IVEC). By using this model we could show that H. pylori use the Lewis b blood group antigen to bind to the host gastric mucosa, during experimental conditions most similar to the in vivo situation. Furthermore, we could show that the host tissue responses to the bacterial attachment by expression of Interleukin 8 (IL- ), which will guide the inflammatory processes. Interestingly, by inhibition of bacterial adhesion through receptor competition i.e., by use of soluble Lewis b antigen, IL-8 production was hampered in the IVEC system, which further validates the presence of a tight relation between bacterial adhesion and induction of host immune responses. One of the inflammation signaling cursors in vivo is the upregulated sialylated Lewis x (sLex) antigen, an inflammation associated carbohydrate structure well established as a binding site for the selectin family of adhesion molecules. We could show that during chronic gastric inflammation, which is actually caused by the persistent H. pylori infection, the bacterial cells adapt their binding mode, and preferentially bind to sLex, which will provide an even more intimate contact with the host cells. This interaction is mediated by SabA, the H. pylori adhesin for sialylated oligosaccharides/glycoconjugates. By employing red blood cells as a model we could further demonstrate that SabA is identical to the “established” H. pylori hemagglutinin. We could also show that SabA binds to sialylated glycolipids (gangliosides) rather than glycoproteins on cell surfaces. Our result also revealed that SabA also binds to and activates human neutrophils. Such effect was unrelated to BabA and the H. pylori Neutrophil Activating Protein (HP- AP), which were not directly involved in the activation of neutrophils. Furthermore, phagocytosis of bacteria by neutrophils was demonstrated to be mainly dependent on presence of SabA. Interestingly, HP-NAP showed a possible role in guiding the bacterial adhesion during conditions of limited sialylation, i.e. equivalent to mild gastritis, when the tissue would be less inflamed and sialylated. In conclusion, H. pylori adhesion causes host tissue inflammation, then the bacteria will adapt to the new condition and bind to epithelial cells in a tighter mode by synergistic activities of BabA and SabA. Additionally, SabA bind to and activate human neutrophils, which will exacerbate inflammation responses and cause damage to host tissue. Thus, BabA and SabA are potential candidates to be targeted for therapeutic strategies against H. pylori and gastric disease.

<p>There have been many cases reported of amphibian populations declining. These are often due to anthropogenic factors such as habitat destruction and pollution. However, some eclines have not had an obvious cause and many of these have been investigated and found to be due to pathogenic disease. Batrachochytrium dendrobatidis is a recently described pathogen of frogs. The population declines that have been associated with chytridiomycosis have occurred in relatively undisturbed areas such as national parks. The declines tend to occur at higher altitudes or in colder climates. This is thought to be because of the frog immune system being slower at lower temperatures. This project gives an overview of chytrid infection in the Western Cape and at a small number of sites in the Northern Cape and Eastern Cape.</p>

Thesis (M.S.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 80-85). Also available via World Wide Web.

Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2009. / Committee Chair: Chernoff, Yury; Committee Member: Bommarius, Andreas; Committee Member: Doyle, Donald; Committee Member: Lobachev, Kirill; Committee Member: Yi, Soojin. Part of the SMARTech Electronic Thesis and Dissertation Collection.