• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 34
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • Tagged with
  • 65
  • 65
  • 11
  • 9
  • 7
  • 5
  • 5
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
21

A study of methods for detection and isolation of Clostridium botulinum Type E from fish of the Great Lakes

Six, David Wyckliffe, January 1968 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
22

Studies on spore resistance and toxigenic characteristics of Clostridium botulinum, type E

Munro, Elma Joan January 1953 (has links)
A brief historical review of Type E botulism is presented. Emphasis is placed on the role of fish in the epidemiology. Experimental details are given of tests carried out on the spore resistance of these Type E strains in comparison with the other types of CI. botulinum. The data obtained indicate that they are more thermolabile than any of the other types, especially A or B. In addition, evidence is presented which shows that the Type E strains seem to be divisible into two groups on the basis of their spore stability. The importance of this thermolability is stressed in regard to isolations of the seemingly rare Type E from suspected foodstuffs or in routine surveys. Details are given also of experiments conducted on the Type E toxins. The effect of dextrose, certain peptones, and colony type on toxin production is discussed. Some experiments on the storage properties of the toxins are presented. Active immunization experiments on mice indicate that Type E toxoids are poor antigens. In only two groups did the mice exhibit demonstrable immunity. Even in these groups the level of immunity was exceedingly variable. By contrast, a Type A toxoid proved a good antigen, protecting mice to a uniformly high degree against the homologous toxin. Efforts to increase the antigenicity of Type E toxoids are discussed. In vitro cross-neutralization tests with four Type E toxins and their antitoxins are described. On the basis of these in vivo and in vitro tests, it is concluded that Type E toxins are not homogeneous: a conclusion supported by the evidence that some Type E toxins contain a chicken-lethal factor, while others do not. This evidence is discussed in relation to the problem of human immunization. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate
23

Distribution of Clostridium botulinum type E in fish, shellfish and the marine environment of the Pacific Northwest, and protein patterns of the toxigenic and non-toxigenic stains

Craig, James Morrison 07 August 1969 (has links)
Interest in the distribution of Clostridium botulinum type E was heightened by the sudden outbreak of human botulism from smoked whitefish chubs and canned tuna fish in 1963. The question arose as to how widely the organism is distributed among fish and shellfish in the Northwest and what potential hazard exists for the consumer of fish products. This sporeforming anaerobic orgnism is heat sensitive and had eluded detection in other surveys where heat shock had been used to eliminate non sporeforming contaminants. More recent study using other techniques than heat to facilitate recovery has shown this organism to be widespread, especially in the marine environment. This study was undertaken to find the incidence and distribution of C. botulinum in the marine organisms and environment of the Pacific Northwest and the food products derived therefrom. All species of fish were examined by incubating the gills and viscera individually in tryptone-peptone-glucose medium anaerobically at 28 C for four days and testing the culture filtrate for mouse toxicity by intraperitoneal injection. Toxic filtrates were typed by retesting them in mice protected by specific botulinal antitoxin of type A, B, E, or F. Among salmonid fish the proportions of specimens of each species yielding toxic filtrates were as follows. Sockeye salmon from the Columbia River, 14 of 59 (23.7%); Chinook salmon from the Columbia River, 19 of 106 (18.0%); Chinook salmon from the Pacific Ocean, 1 of 18 (5,6%); Coho salmon from the Columbia River, 10 of 19 (34.4%); Coho salmon from the Pacific Ocean, 13 of 186 (7.0%); Steelhead trout from the Alsea River, 7 of 37 (19.0%). About one-third of the toxic cultural filtrates were successfully typed and proven to contain botulinal toxin. Most of them proved to be type E toxin but 3 were type A, 3 were type B and one, a comparatively new type, type F, was isolated from a Sockeye salmon in the Columbia River. Pure cultures of Clostridium botulinum type E were isolated from 18 specimens and one specimen yielded a pure culture of type F from a sockeye salmon. This was the second time this type had been isolated. In all of the experimental groups the proportion of fish producing toxigenic cultures was significantly higher in those taken in the two rivers than those of the same species taken from the ocean waters. "Bottom fish" represented by Cod, Sole, Grouper and members of the Sebastodes group were also tested in the manner described above. The number of specimens yielding toxic filtrates were 28 of 157 (17.8%). When grouped according to location at which the fish were caught, those near the mouth of the Columbia River produced a greater percentage of toxic filtrates than did those caught off the open shore line. The results were as follows: Bottom fish from Astoria, 23 of 70 (32.8%), Botton fish from Coos Bay, 5 of 87 (5.6%). Sturgeon specimens produced 3 of 24 (12.5%) toxic filtrates. Most of the species contained type E; however, one type A and one type B were found on typing, with about one-third of the toxic filtrates being successfully typed. Environmental swab samples from the "deep sea" fillet processing plants produced 3 of 39 (7.7%) toxic filtrates. None of the 53 samples taken in the salmon processing plants produced toxic filtrates. Shellfish were collected along the ocean beach and in the estuaries. Three to five shellfish were combined into a single specimen and treated as described. All shellfish obtained from the estuaries demonstrated a higher percentage of toxic filtrates than those obtained from the ocean beach. The results were as follows: Razor clams, 11 of 75 (14.6%), Cockle clams, 12 of 15 (80.0%); Softshell clams, 8 of 12 (66.4%); Littleneck clams, 4 of 11(36.2%); Horseneck clams, 1 of 3 (33.3%); Oysters, 6 of 19 (31.6%); Dungeness crabs, 17 of 24 (71%). Only the razor clams were collected exclusively from the ocean beach. Loss of toxicity on holding mixed cultures at -15 C while awaiting typing was a continual problem. This accounts for only one-third of toxic filtrates being successfully typed. Electrophoretic analysis of the total bacterial proteins was carried out on cell sonicates and cell free culture filtrates by first growing cells for four days at 28 C anaerobically. The cells were separated, washed and disrupted with ultrasonic energy. The cell free culture filtrate was concentrated 10 fold by dialysis against polyethylene glycol 4000. Both the toxigenic organisms and the toxic filtrate demonstrated an extra common protein band in the upper third of the electrophoretic pattern not present in the nontoxic spectra. This band might represent the type E toxin. Differences could also be noted in the number of protein bands in the lower third of the patterns in different nontoxigenic strains and also when the toxigenic and nontoxigenic strains were compared. This could suggest an association with a phage in the toxigenic cultures. / Graduation date: 1970
24

Protoplasts and L-forms of Clostridium botulinum types A and E

Brown, George Walter, January 1970 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.
25

Efeito da acidificação com diferentes ácidos sobre as características sensoriais e inibição do Clostridium botulinum no palmito de pupunha em conserva.

Ruth Vieira de Lemos Vasconcelos, Maria January 2004 (has links)
Made available in DSpace on 2014-06-12T23:03:58Z (GMT). No. of bitstreams: 2 arquivo8838_1.pdf: 358153 bytes, checksum: 333a903dffa4635451ecd7b51c36546b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / A porção comestível do tronco de algumas palmeiras, utilizadas para a produção de palmito é um produto de importância para o Brasil como principal produtor e exportador na forma em coonserva, detendo 85% da produção mundial. A região Nordeste tem se destacado como produtora da variedade pupunha (Bactris gasipaes), nativa da Amazônia, que apresenta vantagens ecológicas por se tratar de palmeira cultivada, com características de perfilhamento, precocidade de produção e qualidade satisfatória. A ocorrência de toxinfecções por Clostridium botulinum provocadas pelo consumo de palmito industrializado levou o Ministério da Saúde a estabelecer a obrigatoriedade do uso de ácido associado à salmoura para produção de palmito com o objetivo de baixar o pH a limites inferiores a 4,5, desfavorecendo o desenvolvimento do Clostridium botulinum, assegurando portanto a saúde do consumidor. Normalmente o ácido cítrico é utilizado para atender as exigências, no entanto admite-se que outros ácidos podem ser utilizados com vantagem quanto aos aspectos sensoriais. Este trabalho teve por objetivo avaliar o efeito da acidificação do palmito de pupunha, cultivado em Pernambuco, com diferentes ácidos sobre as características do produto em conserva. Foram testados os ácidos: cítrico, málico, láctico e tartárico na estabilidade do produto embalado em frascos de vidro com capacidade para 600 ml e quanto às características organolépticas. Os resultados obtidos demonstraram a viabilidade da acidificação do palmito de pupunha com esses diferentes ácidos sem prejuíso nas características físicas, químicas, organolépticas e microbiológicas
26

Exploring the role of the small GTPase Rho in T-lymphocyte biology

Cleverley, Stephen January 2000 (has links)
No description available.
27

Occurrence of Clostridium botulinum type E in shellfish, lake fish and aquatic sediments in the Northwest

Hayes, Sidney Joseph 12 May 1966 (has links)
Comparatively little work has been done to determine the ecology of Clostridium botulinum type E since its initial isolation in the nineteen-thirties. This spore forming, anaerobic microorganism is relatively heat labile and has been missed in ecological surveys in which heat was used to selectively screen for spore formers. Use of gentler methods has, however, facilitated its demonstration in marine sediments throughout the Northern Hemisphere. The type E organism elaborates a highly potent neurotoxin and has been isolated as the causative agent in recent fatalities involving the consumption of fish products. Until recently the organism was not believed to be present in the United States south of the Canadian border. The purpose of this investigation was to determine if the organism could be demonstrated in shellfish, inland lake fish, and sediment samples throughout the Northwest. Samples of coastal shellfish-- including various species of clams, crabs and oysters, varieties of smoked fish products, species of inland lake fish and inland lake, river and coastal sediment samples were examined for the presence of the type E organism. The organism was found, to some extent, in almost every type of sample tested. Type E toxin was demonstrated in incubated samples of shellfish and smoked fish products collected from eleven sites along the Oregon and Washington coast. The organism was found in shore sediments from the tidewater and freshwater areas of the Columbia, Alsea, and Umpqua rivers but could not be demonstrated in sediments taken from saltwater beaches at the mouths of these rivers. The type E organism was also demonstrated in fish from inland lakes in the Oregon Cascade Mountains, in sediments from the shores of these lakes, and along the shores of a river and three reservoirs in this area. These samples were collected between 95 and 120 linear miles from the coast. The isolation of the type E botulinum organism in fish and shellfish products demonstrates that the organism does present a potential hazard which should be recognized by Northwest processors and distributors of these products. High concentrations of the spores of this organism, such as those found in bottom sediments of some of the inland lakes and reservoirs may serve to contaminate fish and other wildlife. Much of the data collected supports a terrestial distribution of the spores. / Graduation date: 1966
28

Impact of parameter variability on the food process engineering calculations required for safety, quality and shelf-life estimations /

Chotyakul, Nattaporn. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 96-104). Also available on the World Wide Web.
29

Development of a novel, rapid, in vitro assay for the detection of Clostridium botulinum neurotoxin type E

Cadieux, Brigitte. January 2001 (has links)
Botulism is a foodborne intoxication caused by ingestion of Clostridium botulinum neurotoxin (BoNT). Preliminary studies focussed on the production of polyclonal antisera against BoNT/E by immunizing a rabbit with botulinal toxoid type E. The antiserum was subsequently used to detect BoNT/E using the slot blot immunoassay where samples were applied to a slot blot filtration manifold and drawn by vacuum through a membrane. The membrane was then immunologically processed before chemiluminescent detection. However, the antisera lacked specificity and cross-reacted with closely related clostridia strains. / The specificity of the antisera was increased by adsorbing cross-reactive antibodies from whole antisera with affinity columns made with total proteins from culture supernatants of closely related clostridia. Alternatively, specific antibodies were isolated with an affinity column prepared with C. botulinum type E toxoid. / Different methods of concentrating BoNT/E in each sample prior to testing them were evaluated to increase the sensitivity of the assay. / The slot blot immunoassay was then evaluated for detection of BoNT/E in mixed cultures and in food samples. (Abstract shortened by UMI.)
30

The occurrence of Clostridium botulinum type E in the Fox River, Wisconsin

Johnson, Jodie, January 1966 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Page generated in 0.0747 seconds