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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.
1

Development of an efficacious recombinant vaccine for the obligate intracellular salmonid pathogen Piscirickettsia salmonis

Kuzyk, Michael Allan 21 February 2018 (has links)
Piscirickettsia salmonis is the aetiological agent of salmonid rickettsial septicaemia (SRS), an economically devastating rickettsial disease of farmed salmonids. SRS responds poorly to antibiotic treatment and no effective vaccine is available for its control. A molecular biology approach was used to characterize and identify antigens of P. salmonis that would be suitable to use as a recombinant subunit vaccine to aid in the control of SRS. A system for routine and reliable growth of P. salmonis was established using a chinook salmon (Oncorhynchus tshawytscha) embryo cell line. A purification protocol to separate P. salmonis from host cell material was devised using a combination of differential and Percoll density gradient centrifugation. Purified P. salmonis was used to generate polyclonal rabbit antisera. Indirect immunofluorescence microscopy, immunogold transmission electron microscopy, and biotin labeling of intact P. salmonis confirmed that P. salmonis was effectively separated from host cell debris and that immunoreactive antigens identified by rabbit antisera were surface associated. Rabbit anti- P. salmonis sera recognized the lipooligosaccharide component of bacterial lipopolysaccharide, and 7 protein antigens with relative mobilities of 27, 24, and 16 kDa and 4 migrating between 50–80 kDa. P. salmonis lipopolysaccharide was observed to be predominantly low m.w., but less abundant high m.w. species containing O-antigen were present. Genomic DNA was isolated from purified P. salmonis and used to construct an expression library in lambda ZAP II. In the absence of preexisting DNA sequence, rabbit polyclonal anti-P. salmonis serum was used to identify immunoreactive clones. A lambda clone encoding an immunoreactive 17 kDa outer surface protein (OspA) of P. salmonis was identified. The 4,983 by insert contained a high molar percentage of adenine and thymine, encoded four intact ORF's, and represented the first non-ribosomal DNA sequence data from P. salmonis. OspA is modified as a bacterial lipoprotein in Escherichia coli and is most closely homologous to a rickettsial 17 kDa surface lipoprotein previously only observed within the genus Rickettsia. A codon optimized version of ospA was constructed and the lipoprotein nature of OspA was determined to be a limiting factor in its production in E. coli. High level production of immunoreactive OspA targeted to inclusion bodies was achieved in E. coli by combining OspA with an N-terminal fusion protein. The OspA fusion was recognized by convalescent salmon sera thereby identifying OspA as an excellent candidate for a recombinant vaccine against P. salmonis. Vaccine preparations using P. salmonis bacterins were found to elicit variable immune responses in coho salmon (Oncorhynchus kisutch) that resulted in either protection or immunosuppression of vaccinates which varied with antigen dosage. Recombinantly produced OspA elicited an astonishing level of protection in vaccinated coho salmon with a relative percent survival (RPS) as high as 59%. In an effort to further improve the efficacy of the OspA recombinant vaccine, T cell epitopes (TCE's) from tetanus toxin and measles virus fusion protein which are universally immunogenic in mammalian immune systems were incorporated into an OspA fusion protein. Addition of the TCE's dramatically enhanced the efficacy of the OspA vaccine, reflected by a 3-fold increase in the number of coho salmon protected (83% RPS). These results represent an effective monovalent recombinant subunit vaccine for the rickettsial pathogen, P. salmonis. / Graduate
2

A study of cell-mediated immunity in subjects vaccinated against Q fever and after Q fever infection /

Izzo, Angelo Antonio. January 1991 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1992. / Copies of author's previously published articles inserted. Includes bibliographical references.
3

Evidence of canine infections with spotted fever-group rickettsiae in southwestern and east central Indiana

Stauffer, Jill M. January 1988 (has links)
A serosurvey was conducted to determine rickettsial infection rates in dogs from two distinct areas in Indiana. Sera were collected from dogs and tested for the presence of antibodies to R. rickettsii, R. montana, R. rhipicephali, and R. bellii using the micro-immunofluoresence test. Results from this study indicate an association between canine and human rickettsial infections. Dogs in southwestern Indiana were found to have significantly higher rickettsial infection rather than those in east central Indiana. Human RMSF cases have also been reported more frequently from southern Indiana.All rickettsial species were detected at some level, with many dogs reacting to more than one antigen Evidence suggests that R. montana is the predominant rickettsial species in Indiana. In addition, indicative of a more suitable tick habitat, dogs sampled from rural areas were seropositive more frequently than the urban/suburban dogs. This study suggests that dogs are exposed to the same tick population as humans and can serve as indicators of the presence of rickettsial agents. Indiana residents should be aware of the potential for RMSF transmission throughout the state. / Department of Physiology and Health Science
4

Evidence for molecular diversity of Piscirickettsia salmonis

Mauel, Michael J. 10 September 1996 (has links)
Graduation date: 1997
5

Distribution and prevalence of Ehrlichia chaffeensis, the causative agent of human monocytic ehrlichiosis, in Indiana and Ohio

Irving, Ryan Powell January 1999 (has links)
Human monocytic ehrlichiosis (HME) is a tick-borne infectious disease caused by the bacterium Ehrlichia chaffeensis and transmitted by the ixodid tick Amblyomma americanum. The first confirmed case of HME in Indiana occurred in 1994. Since then, there have been an additional 17 confirmed cases reported from 11 counties.A total of 498 A. americanum and 25 Dermacentor variabilis ticks were collected from counties in southern Indiana during May and June 1998, pooled, and examined for the presence of E. chaffeensis using nested PCR with primers HE 1 and HE3, which are specific for the 16S rRNA gene of E. chaffeensis. Ten pools of adult A. americanum specimens tested positive for E. chaffeensis DNA. This represented a minimum infection rate (MIR) of 3.82%. None of the A. americanum nymphs or adult D. variabilis ticks tested positive.In addition, 325 white-tailed deer blood samples from Indiana and 327 from Ohio were collected during November, 1998 and tested for the presence of E. chaffeensisreactive antibodies using an indirect immunofluoescence assay (IFA). Evidence of such antibodies was found in deer killed in six Indiana counties where infection rates ranged from 43% - 64% and four Ohio counties where infection rates ranged from 4% - 25%.The results from this study support the view that the distribution of E. chaffeensis closely follows that of A. americanum in the North Central United States. This is the first report of E. chaffeensis-reactive antibodies in white-tailed deer from Ohio. / Department of Biology
6

Pesquisa de infecção por riquétsias do grupo da febre maculosa em cães, pequenos mamíferos e carrapatos em área endêmica e não endêmicas nos biomas Pampa e Mata Atlântica no estado do Rio Grande do Sul / Survey for rickettsial infection of the spotted fever group in dogs, small mammals and ticks in endemic and non-endemic areas of the Pampa and Atlantic forest biomes in the state of Rio Grande do Sul

Felipe da Silva Krawczak 05 August 2016 (has links)
Em 2005 o primeiro caso de Febre Maculosa Brasileira (FMB) foi reconhecido no estado do Rio Grande do Sul (RS), Brasil. Desde então até abril de 2016 doze casos foram confirmados, sendo que quatro destes são autóctones do município de Cerro Largo, área considerada endêmica para a enfermidade riquetsial. Neste mesmo período o RS também notificou 58 casos suspeitos ao Ministério da Saúde. No RS são encontrados dois biomas, Mata Atlântica e Pampa, este último não ocorrendo em outras unidades federativa do país. Até o momento, inexistem estudos relatando a infecção por riquétsias na ixodofauna gaúcha. Desta forma, o presente estudo teve como objetivo pesquisar a infecção de riquétsias do Grupo da Febre Maculosa (GFM) em cães, pequenos mamíferos e carrapatos; através da Reação de Imunofluorescência Indireta (RIFI), qPCR e tentativa de isolamento de riquétsias em cultivo celular dos ixodídeos coletados em área endêmica (Cerro Largo) e áreas não endêmicas nos biomas Pampa e Mata Atlântica no RS. Na sorologia (RIFI), 33,5 % (55/164), 2,9% (1/33), 40% (16/40) dos pequenos mamíferos e 8,3% (3/36), 13,9% (5/36) e 20,4 (28/137) dos cães coletados na Mata Atlântica, Pampa e área endêmica para FMB, respectivamente, foram sororreagentes para pelo menos um dos seis antígenos de riquétsias testados. Oito espécies de carrapatos foram coletadas no local de Mata Atlântica, sendo: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Ixodes loricatus, Rhipicephalus microplus e Amblyomma yucumense com destaque para esta última que foi descrita como uma espécie nova. Já para o fragmento de Pampa quatro espécies foram encontradas (A. aureolatum, A. ovale, Amblyomma tigrinum e Rhipicephalus sanguineus) e na área endêmica para FMB no RS, coletamos cinco espécies de carrapatos, Amblyomma dubitatum, Amblyomma longirostre, A. ovale, I. loricatus e R. microplus. Detectamos molecularmente pela primeira vez no RS, Candidatus Rickettsia amblyommii em A. longirostre e A. brasiliense, Candidatus Rickettsia andeanae em A. aureolatum e A. tigrinum, Rickettsia bellii em I. loricatus, Rickettsia rhipicephali em A. yucumense e H. juxtakochi, Candidatus Rickettsia asemboensis em pulgas no Brasil e de extrema importância para o conhecimento da epidemiologia da FMB no RS, detectamos Rickettsia sp. cepa Mata Atlântica em A. ovale oriundos de Cerro Largo (área endêmica para FMB no RS). Como primeiros isolamentos de riquétsia para o estado do RS, isolamos R. bellii de I. loricatus coletados na Mata Atlântica e área endêmica para FMB no RS. O presente estudo é pioneiro em relação a investigação comparativa sobre FMB nos biomas Pampa e Mata Atlântica e também o primeiro estudo molecular e isolamento de riquétsias em cultivo celular de amostras coletadas no RS, Brasil / In 2005 the first Brazilian Spotted Fever (BSF) case was confirmed in the Rio Grande do Sul (RS) state, Brazil. Ever since until April 2016, twelve cases have been confirmed, and four of them are native from Cerro Largo city, an area considered endemic to the riquetsial illness. During the same period, RS also notified 58 suspected cases to the Ministry of Health. There are two distinct biomes in RS, Atlantic Forest and Pampa, the later restricted to RS within the Brazilian land. Until now, no studies reported rickettsial infection in the ixodofauna of RS. Thus, this study aimed to investigate the rickettsial infection of Spotted Fever Group (SFG) in dogs, small mammals and ticks; by immunofluorescence assay (IFA), qPCR and attempted rickettsial isolation in cell culture from ticks collected in an endemic area (Cerro Largo) and non-endemic areas in Pampa and Atlantic Forest biomes of RS. Through serology (IFA), 33.5% (55/164), 2.9% (1/33) and 40% (16/40) small mammals, and 8.3% (3/36), 13.9 % (5/36) and 20.4 (28/137) dogs from the Atlantic Forest, Pampa, and BSF-endemic area, respectively, were seroreactive (titer ≥64) to at least one of the six rickettsia antigens tested. Eight species of ticks were collected in the Atlantic Forest: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Ixodes loricatus, Rhipicephalus microplus and Amblyomma yucumense, the later described as a new species. In the Pampa fragment, four tick species were found (A. aureolatum, A. ovale, Amblyomma tigrinum and Rhipicephalus sanguineus), and five tick species (Amblyomma dubitatum, Amblyomma longirostre, A. ovale, I. loricatus, R. microplus) in the BSF-endemic area of RS. We performed the first molecular detection in the RS state of "Candidatus Rickettsia amblyommii" in A. longirostre and A. brasiliense; "Candidatus Rickettsia andeanae" in A. aureolatum and A. tigrinum; Rickettsia bellii in I. loricatus; Rickettsia rhipicephali in A. yucumense and H. juxtakochi; and "Candidatus Rickettsia asemboensis" in fleas in Brazil. Noteworthy, we detected the pathogen Rickettsia sp. strain Atlantic rainforest in A. ovale ticks from Cerro Largo (endemic area for BSF in RS). We also performed the first isolation in cell culture of rickettsia from RS state, which comprised R. bellii from I. loricatus collected in the Atlantic Forest and the BSF-endemic area. This study is the first comparative research about rickettsiae among Pampa and Atlantic Forest biomes, and also the first molecular detection and isolation in cell culture of rickettsiae from Rio Grande do Sul, Brazil
7

Pesquisa de infecção por riquétsias do grupo da febre maculosa em cães, pequenos mamíferos e carrapatos em área endêmica e não endêmicas nos biomas Pampa e Mata Atlântica no estado do Rio Grande do Sul / Survey for rickettsial infection of the spotted fever group in dogs, small mammals and ticks in endemic and non-endemic areas of the Pampa and Atlantic forest biomes in the state of Rio Grande do Sul

Krawczak, Felipe da Silva 05 August 2016 (has links)
Em 2005 o primeiro caso de Febre Maculosa Brasileira (FMB) foi reconhecido no estado do Rio Grande do Sul (RS), Brasil. Desde então até abril de 2016 doze casos foram confirmados, sendo que quatro destes são autóctones do município de Cerro Largo, área considerada endêmica para a enfermidade riquetsial. Neste mesmo período o RS também notificou 58 casos suspeitos ao Ministério da Saúde. No RS são encontrados dois biomas, Mata Atlântica e Pampa, este último não ocorrendo em outras unidades federativa do país. Até o momento, inexistem estudos relatando a infecção por riquétsias na ixodofauna gaúcha. Desta forma, o presente estudo teve como objetivo pesquisar a infecção de riquétsias do Grupo da Febre Maculosa (GFM) em cães, pequenos mamíferos e carrapatos; através da Reação de Imunofluorescência Indireta (RIFI), qPCR e tentativa de isolamento de riquétsias em cultivo celular dos ixodídeos coletados em área endêmica (Cerro Largo) e áreas não endêmicas nos biomas Pampa e Mata Atlântica no RS. Na sorologia (RIFI), 33,5 % (55/164), 2,9% (1/33), 40% (16/40) dos pequenos mamíferos e 8,3% (3/36), 13,9% (5/36) e 20,4 (28/137) dos cães coletados na Mata Atlântica, Pampa e área endêmica para FMB, respectivamente, foram sororreagentes para pelo menos um dos seis antígenos de riquétsias testados. Oito espécies de carrapatos foram coletadas no local de Mata Atlântica, sendo: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Ixodes loricatus, Rhipicephalus microplus e Amblyomma yucumense com destaque para esta última que foi descrita como uma espécie nova. Já para o fragmento de Pampa quatro espécies foram encontradas (A. aureolatum, A. ovale, Amblyomma tigrinum e Rhipicephalus sanguineus) e na área endêmica para FMB no RS, coletamos cinco espécies de carrapatos, Amblyomma dubitatum, Amblyomma longirostre, A. ovale, I. loricatus e R. microplus. Detectamos molecularmente pela primeira vez no RS, Candidatus Rickettsia amblyommii em A. longirostre e A. brasiliense, Candidatus Rickettsia andeanae em A. aureolatum e A. tigrinum, Rickettsia bellii em I. loricatus, Rickettsia rhipicephali em A. yucumense e H. juxtakochi, Candidatus Rickettsia asemboensis em pulgas no Brasil e de extrema importância para o conhecimento da epidemiologia da FMB no RS, detectamos Rickettsia sp. cepa Mata Atlântica em A. ovale oriundos de Cerro Largo (área endêmica para FMB no RS). Como primeiros isolamentos de riquétsia para o estado do RS, isolamos R. bellii de I. loricatus coletados na Mata Atlântica e área endêmica para FMB no RS. O presente estudo é pioneiro em relação a investigação comparativa sobre FMB nos biomas Pampa e Mata Atlântica e também o primeiro estudo molecular e isolamento de riquétsias em cultivo celular de amostras coletadas no RS, Brasil / In 2005 the first Brazilian Spotted Fever (BSF) case was confirmed in the Rio Grande do Sul (RS) state, Brazil. Ever since until April 2016, twelve cases have been confirmed, and four of them are native from Cerro Largo city, an area considered endemic to the riquetsial illness. During the same period, RS also notified 58 suspected cases to the Ministry of Health. There are two distinct biomes in RS, Atlantic Forest and Pampa, the later restricted to RS within the Brazilian land. Until now, no studies reported rickettsial infection in the ixodofauna of RS. Thus, this study aimed to investigate the rickettsial infection of Spotted Fever Group (SFG) in dogs, small mammals and ticks; by immunofluorescence assay (IFA), qPCR and attempted rickettsial isolation in cell culture from ticks collected in an endemic area (Cerro Largo) and non-endemic areas in Pampa and Atlantic Forest biomes of RS. Through serology (IFA), 33.5% (55/164), 2.9% (1/33) and 40% (16/40) small mammals, and 8.3% (3/36), 13.9 % (5/36) and 20.4 (28/137) dogs from the Atlantic Forest, Pampa, and BSF-endemic area, respectively, were seroreactive (titer ≥64) to at least one of the six rickettsia antigens tested. Eight species of ticks were collected in the Atlantic Forest: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Ixodes loricatus, Rhipicephalus microplus and Amblyomma yucumense, the later described as a new species. In the Pampa fragment, four tick species were found (A. aureolatum, A. ovale, Amblyomma tigrinum and Rhipicephalus sanguineus), and five tick species (Amblyomma dubitatum, Amblyomma longirostre, A. ovale, I. loricatus, R. microplus) in the BSF-endemic area of RS. We performed the first molecular detection in the RS state of "Candidatus Rickettsia amblyommii" in A. longirostre and A. brasiliense; "Candidatus Rickettsia andeanae" in A. aureolatum and A. tigrinum; Rickettsia bellii in I. loricatus; Rickettsia rhipicephali in A. yucumense and H. juxtakochi; and "Candidatus Rickettsia asemboensis" in fleas in Brazil. Noteworthy, we detected the pathogen Rickettsia sp. strain Atlantic rainforest in A. ovale ticks from Cerro Largo (endemic area for BSF in RS). We also performed the first isolation in cell culture of rickettsia from RS state, which comprised R. bellii from I. loricatus collected in the Atlantic Forest and the BSF-endemic area. This study is the first comparative research about rickettsiae among Pampa and Atlantic Forest biomes, and also the first molecular detection and isolation in cell culture of rickettsiae from Rio Grande do Sul, Brazil
8

A study of cell-mediated immunity in subjects vaccinated against Q fever and after Q fever infection / Angelo Antonio Izzo

Izzo, Angelo Antonio January 1991 (has links)
Copies of author's previously published articles inserted / Includes bibliographical references / [ix], 261, [101] leaves, [4] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1992
9

Investigation of rickettsioses and other causes of acute undifferenciated fever in Vietnam / Examen des rickettsioses et autres causes de fièvre aigüe indifférenciée au Vietnam

Le Viet, Nhiem 23 November 2018 (has links)
Les infections rickettsiales et la fièvre aiguë indifférenciée (FAI) sont des problèmes de santé publique importants sous les tropiques. Ce projet a été réalisé dans le but d'explorer les agents de rickettsies et autres étiologies de la FAI au Vietnam.Dans la première cohorte de 67 participants se concentrant sur les patients cliniquement suspectés de typhus des broussailles, le diagnostic de typhus des broussailles a été confirmé pour 32 patients (47,8%) par qPCR ou IFA. Parmi les 20 patients pour lesquels des escarres et du sang total ont été obtenus, 17 (85%) des échantillons d'escarre et 5 (25%) des échantillons de sang total étaient positifs pour O. tsutsugamushi par qPCR. L'analyse génétique des séquences du gène TSA 56-kDa a démontré que les 14 séquences étaient apparentées à 4 génotypes: Karp, Kawasaki, Gilliam (JG-v et TG-v) et TA716. Ensuite, une analyse prospective des étiologies de la FAI au Vietnam a été réalisée avec 378 patients adultes fébriles (FAIs) et 384 patients adultes fébriles (Contrôles). L'étiologie la plus courante était le virus de la grippe (20,9% dans les FAIs versus 0% dans les Contrôles), suivi des rickettsies (11,11% vs 0,26%), virus de la dengue (7,67% vs 0,52%), Leptospira (4,76% vs 0,78%), adénovirus (4,76% vs 1,04%) et entérovirus (2,12% vs 0%) (p<0,05).Par conséquent, de telles données sur les rickettsies et autres étiologies obtenues au Vietnam pourraient être très utiles pour l’établissement d’une méthode d’approche pour les patients atteints de FAI dans les aspects de diagnostic, de gestion et de prévention au Vietnam et dans les régions tropicales dans l'avenir. / Rickettsial infections and acute undifferentiated fever (AUF) are the important public health issues in the tropics. This project was performed with the aim to explore the rickettsial agents and other etiologies of AUF in Vietnam. In the first 67-participant cohort of patients who were clinically suspected of having scrub typhus, 32 (47.8%) patients were confirmed as scrub typhus by either qPCR or IFA. Among the 20 patients for whom both eschar and whole blood were obtained, 17 (85%) of the eschar specimens and 5 (25%) of the whole blood specimens tested positive for O. tsutsugamushi by qPCR. Genetic analysis of the 56-kDa TSA gene sequences demonstrated that the 14 sequences were related to 4 groups: Karp, Kawasaki, Gilliam (JG-v and TG-v) and TA716.Subsequently, a prospective case-control analysis of the etiologies of AUF in Vietnam was performed. A total of 378 febrile adult patients (AUFs) and 384 afebrile adult patients (Controls) were enrolled. The most common etiology was influenza virus (20.9% in AUFs versus 0% in Controls), followed by rickettsial agents (11.11% in AUFs versus 0.26% in Controls), dengue virus (7.67% vs 0.52%), Leptospira (4.76% vs 0.78%), adenovirus (4.76% vs 1.04%), and enterovirus (2.12% vs 0%) (p<0.05). Consequently, such data of rickettsial agents and other etiologies in Vietnam obtained from this project are extremely useful in guiding the diagnosis, management and preventive-health methods for patients with AUF in the future in Vietnam as well as in the tropics worldwide.
10

Determination of the possible role of arthropods as vectors for "Potomac Horse Fever" in equines

Fletcher, Michael Gordon January 1987 (has links)
Potomac Horse Fever (PHF) is a disease of great concern to many horse owners in the Potomac River area of Maryland and Virginia. It is caused by a rickettsia, Ehrlichia risticii. The involvement of an arthropod vector has been suspected because of the seasonal epidemiology of the disease. This research was an attempt to identify and evaluate potential arthropod vectors. A seasonal activity study of biting arthropods attacking horses in endemic areas of Maryland and Virginia identified five potential vectors: (1) Simulium jenningsi (Diptera: Simuliidae), (2) Stomoxys calcitrans (Diptera: Muscidae), (3) Culicoides obsoletus (Diptera: Ceratopogonidae), (4) C. variipennis, and (5) Dermacentor variabilis (Acari: Ixodidae). These five arthropod species were given status as potential vectors because they were collected feeding on horses just prior to and throughout the PHF season. Simulium jenningsi and D. variabilis have the closest seasonal association with the occurrence of PHF as presented in this study. D. variabilis was determined to have the greatest potential due to its reported association with other rickettsial diseases. A series of laboratory and field studies were designed to examine the potential role of D. variabilis in the transmission of E. risticii. We first attempted to transmit E. risticii by feeding adult D. variabilis collected from an endemic farm on susceptible horses. Other laboratory studies included mouse to horse and mouse to mouse transmission attempts using ticks fed on mice inoculated with E. risticii. A serological survey of 105 trapped field rodents (host of immature D. variabilis) on endemic farms in Maryland showed all specimens collected to be negative for PHF antibodies. These studies and others gave no indication of D. variabilis's involvement in the transmission of the disease in nature. The other species mentioned above were not examined. / Ph. D.

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