Blueberry bushes with scorch symptoms were found during a survey of blueberry fields in British Columbia, Washington, and Oregon. Some of these bushes were infected with blueberry scorch virus (BBScV) while others contained a second virus which was sap transmissible to Nicotiana clevelandii, N. benthamiana, and N. tabacum cv. 'Havana 425' . This virus was purified from N. clevelandii and had isometric particles of approximately 30 nm in diameter, a coat protein subunit of 27,500 daltons and a tripartite genome. I was unable to transfer the virus from either infected N. clevelandii or infected blueberry to healthy N. clevelandii with Myzus persicae or Fimbriaphis fimbriata. Serological tests of this blueberry virus with antisera against members of the ilar-, cucumo-, bromo-, or nepovirus groups failed to indicate any relationship. In a subsequent survey using enzyme-linked immunosorbent assay, this isometric virus was found in blueberry plants from northern Washington state to central Oregon but has not yet been found in B.C. Of the established members of the carlavirus group examined, BBScV is most closely related to potato virus S (PVS) and less closely related to carnation latent virus (CLV) and potato virus M (PVM). The difference in host range between BBScV and PVS would indicate that the BBScV is not a strain of PVS but is a separate virus that is related to PVS. Therefore, BBScV should be renamed blueberry scorch carlavirus (BBSCV). BBSCV was also compared to a carlavirus isolated from blueberry in the Sheep Pen Hill blueberry growing area of New Jersey (referred to as SPHV). These viruses were compared serologically and by use of nucleic acid hybridizations. BBSCV and SPHV were found to be closely related and were concluded to be strains of the same virus. SPHV should be named the New Jersey strain of BBSCV. / Land and Food Systems, Faculty of / Graduate

This study evaluates the outcomes of a hospital-based cardiac rehabilitation program designed to deliver the first phase of cardiac rehabilitation services at home. The program was established in a community hospital in 1985, operating under the administration of the hospital's Medical Day Centre. Patients suffering from acute myocardial infarction (MI) are referred to the program by their physician and receive services from a cardiac nurse specialist immediately upon discharge. The services continue for a period of 6 weeks. The outcomes of importance in the study are the effects of the program on hospital services in the initial 10 month period and on patient's health related behaviour 3 months post infarction. Results of the study indicate that program goals were achieved during the initial 10 months of the study. Physicians referred 92% of the eligible patients and the average length of stay (ALOS) in hospital was satisfactorily reduced. For patients with uncomplicated MI the ALOS was 8.6 days by the tenth month. At 3 month follow up, patients reported significant improvements over their pre infarction health related behaviour. There were significant increases in the frequency of light exercise (p<-0005), in the regular use of low fat dairy products (p=.0003) and in the practice of restricting calories (p=.003) while significant decreases were reported in the frequency of consuming fried foods (p<.0005), salted foods (p<.0005) and rich foods (p<.005) and in the regular use of table salt (p=.00003). Smoking cessation was reported by 50% of the smokers at follow up. Patients reported a high level of satisfaction with the program, describing the service as well timed, informative, practical and valuable in restoring their self confidence. While these results were satisfactory with regards to the program goals, the evaluation was based on a single group design and further investigation is desirable with comparisons between hospitals and between patients with and without exposure to the program. / Medicine, Faculty of / Population and Public Health (SPPH), School of / Graduate

The generation of oxygen free radicals by the cytosolic enzyme, xanthine oxidase (XO), has been implicated in post-ischemic or reperfusion damage in several organs. XO catalyzes the conversion of hypoxanthine to urate with the concomitant production of superoxide anion free radical (0₂̅˙) and hydrogen peroxide (H₂O₂). Oxygen free radical-mediated injury has also been demonstrated in inflammatory lung disease. The possible involvement of XO in oxidative injury in the lung has not yet been studied. Therefore, this research project was designed to determine whether XO is present in the lung and to investigate its characteristics in porcine, bovine, rat and human lung and other tissues. Immunochemical analysis of xanthine oxidase in the tissues employed on polyclonal antibody raised to bovine milk XO. Proteins were separated by SDS-polyacrylamide gel electrophoresis of tissue homogenates. Proteins were transfered from the gels to nitrocellulose filters by Western blotting. After incubating the filters with a antisera containing the antibody to the purified bovine XO. XO on the filter was detected by its reaction with an enzyme-conjugated second antibody. XO was immunologically detectable in bovine lung and milk. Rat lung, kidney and liver all showed XO reactivity. XO was detectable in porcine liver but not detectable in porcine lung or kidney. Thus, the antibody to bovine XO was cross-reactive with porcine and rat XO. XO protein was not immunologically detectable in human lung possibly because the antibody was not cross reactive with the bovine antibody. In vivo, xanthine oxidase exists predominantly as a dehydrogenase rather than an oxidase. In this form as xanthine dehydrogenase (XDH) the enxyme does not produce either 0₂̅˙ or H₂O₂. The activity of both XDH and XO was measured in several tissues using a fluorometric assay which uses an artifical substrate, pterin which is catalytically converted to the fluorescent product isoxanthopterin (IXP). XO activity in porcine liver was of 1.1 x 10⁻³ µg IXP/mg protein/min although XO activity was not detectable in porcine lung and kidney, in rat lung of 1.7 x 10⁻² µg IXP/mg protein/min, rat kidney of 1.5 x 10⁻² µg IXP/mg protein/min, and rat liver of 2.2 x 10⁻² µg IXP/mg protein/min. Seven human lung biopsy samples were obtained after lung resection and initially tested for viability by determination of NADH oxidase activity and then assayed for XO-XDH. Three of these samples showed NADH oxidase activity indicating tissue viability, but only one of these three showed measurable XO activity of 5.35 x 10⁻⁶ µg IXP/mg protein/min. Irreversible conversion of XDH to XO is thought to be the result of limited proteolysis by a Ca²⁺/calmodulin activated protease, whereas reversible conversion of the enzyme occurs by oxidation of critical thiol groups. Studies on the rate and nature of fluorescence assay to detect catalytic activities of both enzyme forms. Incubation of lung homogenates with trypsin for 60 min caused irreverisble conversion of 90% of the XDH to XO. In contrast, incubation of homogenates at 15°C for 10 hours caused conversion of 100% of the XDH to XO. This conversion was reversible to the extent of 80% by reduction of thiol groups with dithiothreitol (DTT). The effects of free Ca²⁺ on the conversion of XDH to X0 was examined by using EDTA, a chelator of Ca²⁺ and other divalent cations; and EGTA, a more specific chelator of Ca²⁺. The presence of these chelating agents during homogenization of either normoxic or ischemic rat lung tissue did not inhibit reversible enzyme conversion. Increased XO activity was reversible by DTT. In the normoxic rat lung, homogenates prepared with EDTA and EGTA showed a similar conversion of 95% of XDH to XO which was reversible to 70% with DTT. In the ischemic rat lung, samples prepared with EDTA and EGTA showed a'conversion of 80% and 95% XDH to XO which was similar to control samples. The extent of reversibility to XDH was 75% with DTT incubation. In addition, perfusion of rat lungs with EDTA and DTT via a pulmonary artery cannula prior to 60 min of ischemia and homogenization did not affect the extent of XDH to XO conversion. These results indicate that irreversible Ca²⁺-mediated proteolytic conversion of XDH to XO does not occur to a great extent in the rat lung during either normoxia or ischemia. However, reversible conversion of XDH to XO does occur, suggesting that reversible thiol dependent conversion may play a role in the lung under both physiological and pathophysiological states. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Various natural environments have been examined for the presence of antibiotic-resistant bacteria and/or novel resistance mechanisms, but little is known about resistance in the terrestrial deep subsurface. This study examined two deep environments that differ in their known period of isolation from surface environments and the bacteria therein. One hundred and fifty-four strains of bacteria were isolated from sediments located 170-259 m below land surface at the U.S. Department of Energy Savannah River Site (SRS) in South Carolina and Hanford Site (HS) in Washington. Analyses of 16S rRNA gene sequences showed that both sets of strains were phylogenetically diverse and could be assigned to several genera in 3-4 phyla. All of the strains were screened for resistance to 13 antibiotics by plating on selective media and 90% were resistant to at least one antibiotic. 86% of the SRS and 62% of the HS strains were resistant to more than one antibiotic. Resistance to naladixic acid, mupirocin, or ampicillin was noted most frequently. The results indicate that antibiotic resistance is common among subsurface bacteria. The somewhat higher frequencies of resistance and multiple resistance at the SRS may, in part, be due to recent surface influence, such as exposure to antibiotics used in agriculture. However, the HS strains have never been exposed to anthropogenic antibiotics but still had a reasonably high frequency of resistance. Given their long period of isolation from surface influences, it is possible that they possess some novel antibiotic resistance genes and/or resistance mechanisms. Seven of the strains from the HS that are resistant to tetracycline were examined for the presence of a novel antibiotic resistance gene. From these seven strains, a novel tetracycline resistance determinant was characterized. The predicted amino acid sequence shares only a 30% sequence similarity with TetA(Z), the most closely related previously described determinant. The new protein is a putative efflux pump with several characteristics in common with previously characterized efflux pumps including: a divergently transcribed TetR repressor, conserved GxxSDRxGRR motif, and transmembrane domains. The determinant has been assigned the name Tet 42. Functional genes from another subset of 11 HS strains that are resistant to ciprofloxacin were sequenced for resistance-conferring mutations. The most common mechanism of resistance to this antibiotic is based on mutations in the functional genes for DNA gyrase (gyrA, gyrB) and topoisomerase II (parC, parE). Sequences for the genes gyrA, gyrB, and parC in resistant strains were compared to the same sequences from ciprofloxacin-sensitive strains from the HS and Escherichia coli. The strains grouped into three genera: Arthrobacter, Sphingomonas, and Pseudomonas. All of the resistant strains possessed some mutations in their gyrase and/or topoisomerase genes that result in the substitution of amino acids not seen in the gene products of E. coli and the sensitive strains. These mutations, some of which have not been reported previously, can be considered putative resistance-conferring mutations. The resistant subsurface strains were also grown in the presence of an efflux pump inhibitor, and a majority of the cultures did not grow when the inhibitor was added. Lack of growth in the presence of the inhibitor may indicate that ciprofloxacin resistance is due entirely or in part to an efflux pump. The presence of an efflux pump might also explain why some of the strains with a higher minimum inhibitory concentration (MIC) have fewer mutations in their gyrase and/or topoisomerase genes than do strains with a lower MIC. It is possible that, along with novel mutations that may play a role in resistance, these strains also posses an uncharacterized efflux pump. A third approach used in this study to examine novel antibiotic resistance mechanisms was to look at differences in the entire proteome under normal and stressed conditions. The strain G887 is resistant to tetracycline and possesses the tetracycline resistance determinant Tet 42. Cultures of this strain were grown with tetracycline and without tetracycline. Protein extractions were performed from each culture and separated in the 1st dimension according to pI, on 4-7 Isoelectric Focusing Strips (IEF) strips and 6-11 IEF strips. After the 1st dimension separation, the proteins were separated by molecular weight on 12% acrylamide gels. The gels were stained with a fluorescent stain, imaged, and analyzed with spot analysis software. The gels run with the proteins from the tetracycline-treated culture indicated that several proteins visualized on both the 4-7 and 6-11 gels were upregulated in the presence of tetracycline. Some of these spots correspond to the molecular weight and pI for Tet A(42) or to those of several previously described general stress proteins. This work demonstrates that there is a high frequency of antibiotic resistance in the deep terrestrial subsurface and that bacteria in this environment possess uncharacterized antibiotic resistance genes and mutations that confer resistance. Given the constant emergence of antibiotic-resistant pathogenic strains in clinical settings and the problems this creates with respect to the treatment of bacterial diseases, it becomes increasingly important to characterize antibiotic resistance genes that may exist in the environment but have not yet been transferred to clinically important species. Our ability to alter existing antibiotics or develop new drugs to counter novel resistance mechanisms will be dependent on such characterizations. It might also be worthwhile to investigate subsurface bacteria for the ability to produce antibiotics themselves. There is a real potential for novel antibiotic discovery, given the length of time these bacteria have been isolated from antibiotic-producing bacteria in surface environments. / A Dissertation submitted to the Department of Biomedical Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2008. / October 3, 2008. / Antibiotic Resistance, Bacteria, Subsurface / Includes bibliographical references. / David L. Balkwill, Professor Directing Dissertation; Hank W. Bass, Outside Committee Member; Graham A. Patrick, Committee Member; Branko Stefanovic, Committee Member.

No description available.

A new disease affecting potatoes was first detected in Mexico in 1993. Affected plants had aerial symptoms similar to those caused by potato purple top and psyllid yellows, but tubers had internal brown discoloration when sliced and dark stripes and streaks when processed to produce potato chips. The disease has been found in many potato production areas in Guatemala, Mexico, Honduras, New Zealand and the United States. The disease, termed Zebra Chip (ZC), has been associated with the presence of heavy infestations of the potato-tomato psyllid (Bactericera cockerelli). In 2009, a research group in New Zealand discovered that a new disease in tomato and pepper plants was caused by Candidatus Liberibacter solanacearum (Lso) and subsequently this same bacterium was associated with ZC in potato samples from Texas. The objectives of this study were: to assess the accumulation of Lso in various potato organs, to determine the effect of plant age on detection of Lso, symptom development and plant death, and (iii) to determine the effect of phosphorous acid on the development of ZC. Results from these studies showed significant differences in Lso populations between above and below ground tissues of the potato plant, with Lso populations in stolons and tubers being three to four times higher than those of leaf tissue and over seventy times greater than in stems. Time for detection of Lso by PCR in potato leaves of different ages at the time of inoculation ranged from 21 to 26 days after inoculation, symptoms development took 23 to 36 days. Plant death, took 24 to 47 days in plants of different age groups at the time of inoculation. In plants 15 weeks old at the time of inoculation, Lso was detected after 14 days in one plant out of 18; in plants 16 weeks old at the time of inoculation, Lso was detected after seven days in two plants out of 18. Phosphorous acid applications had no effect on the populations of Lso in potato tubers, onset of symptoms or plant death. All tubers showed ZC symptoms, making them unacceptable for the market. / North Dakota State University. Department of Plant Pathology

A Thesis Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the Degree of Doctor of Philosophy / The Epidemiology, occurrences and effect of BMV (Brome Mosaic virus) wheat (triticum aestivum) in the summer rainfall area. (Abbreviation abstract) / AC 2018

No description available.

No description available.

No description available.