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  • 1
    Monographie ausleihbar
    Monographie ausleihbar
    Melbourne : Longman
    Signatur: 2/M 98.0153
    Materialart: Monographie ausleihbar
    Seiten: x, 126 S.
    Ausgabe: 2nd ed.
    ISBN: 0582803128
    Klassifikation:
    Informationswesen
    Sprache: Englisch
    Standort: Lesesaal
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract. Shellfish have been identified as a potential source of Cryptosporidium infection for humans. The inactivation of C. parvum and other pathogens in raw molluscan shellfish would provide increased food safety for normal and at-risk consumers. The present study examined the efficacy of two alternative food-processing treatments, e-beam irradiation and microwave energy, on the viability of C. parvum oocysts in Eastern Oysters (Crassostrea virginica), which were artificially infected with the Beltsville strain of C. parvum. The effects of the treatments were evaluated by oral feeding of the processed oyster tissues to neonatal mice. Significant reductions (P〈0.05) in infectivity were observed for in-shell and shucked oysters treated with e-beam irradiation at doses of 1.0, 1.5, or 2 kGy vs. untreated controls. A dose of 2 kGy completely eliminated C. parvum infectivity and did not adversely affect the visual appearance of the oysters. Oyster tissue treated with microwave exposures of 1 s (43.2°C), 2 s (54.0°C), and 3 s (62.5°C) showed a reduction in C. parvum mouse infectivity, but the effects were not significantly different (P〉0.05) from controls. Microwave energy treatments at 2 and 3 s showed extensive changes in oyster meat texture and color. Thus, because of lack of efficacy and unacceptable tissue changes, microwave treatment of oysters is not considered a viable food-processing method.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract. Shellfish have been identified as a potential source of Cryptosporidium infection for humans. The inactivation of Cryptosporidium parvum and other pathogens in raw molluscan shellfish would provide increased food safety for normal and at-risk consumers. The present study identified the efficacy of a non-thermal alternative food-processing treatment, high hydrostatic pressure processing (HPP), on the viability of C. parvum oocysts in the Eastern oysters Crassostrea virginica. Oysters were artificially exposed to 2 × 107 oocysts of the Beltsville strain of C. parvum in seawater and subjected to HPP treatments. The effects of the treatments were evaluated by inoculation of the processed oyster tissues into neonatal mice. High-pressure processing of shucked Eastern oysters at all pressures tested (305, 370, 400, 480, and 550 MPa) was significantly effective (P〈0.05) in reducing the numbers of positive mouse pups fed treated oyster tissues exposed to C. parvum oocysts. A dose of 550 MPa at 180 s (s) of holding time produced the maximum decrease in numbers of C. parvum positive mouse pups (93.3%). Measurement of tristimulus color values of HPP-treated raw oysters at extended processing times from 120 s to 360 s at 550 MPa showed a small increase in whiteness of oyster meat. This non-thermal processing treatment shows promise for commercial applications to improve safety of seafood and reduce public health risks from cryptosporidiosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: . Toxoplasma gondii is an important apicomplexan parasite of humans and other warm-blooded animals. Ponazuril is a triazine anticoccidial recently approved for use in horses in the United States. We investigated the inode of action of ponazuril against developing RH strain T. gondii tachyzoites in African green monkey kidney cells. Host cells were infected with 2.0 × 105 tachyzoites and treated with 5 μg/ml ponazuril. Cultures were fixed and examined by transmission electron microscopy 3 days after treatment. Ponazuril interfered with normal parasite division. This led to the presence of multinucleate schizonts stages. Up to six tachyzoites were observed partially budded from the surface of these schizonts. Large vacuoles developed in these schizonts and they eventually degenerated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: . We have been collaborating since 1992 in studies on southern sea otters (Enhdyra lutris nereis) as part of a program to define factors, which may be responsible for limiting the growth of the southern sea otter population. We previously demonstrated Toxoplasma gondii in sea otiers. We postulated that cat feces containing oocysts could be entering the marine environment through storm run-off or through municipal sewage since cat feces are often disposed down toilets by cat owners. The present study examined the sporulation of T. gondii oocysts in seawater and the survival of sporulated oocysts in seawater. Unsporulated oocysts were placed in 1.5 ppt artificial seawater, 32 ppt artificial seawater or 2% sulfuric acid (positive control) at 24 C in an incubator. Samples were examined daily for 3 days and development monitored by counting 100 oocysts from each sample. From 75 to 80% of the oocysts were sporulated by 3 days post-inoculation under all treatment conditions. Groups of 2 mice were fed 10,000 oocysts each from each of the 3 treatment groups. All inoculated mice developed toxoplasmosis indicating that oocysts were capable of sporulating in seawater. Survival of sporulated oocysts was examined by placing sporulated T. gondii oocysts in 15 ppt seawater at room temperature 22–24 C (RT) or in a refrigerator kept at 4 C. Mice fed oocysts that had been stored at 4C or RT for 6 months became infected. These results indicate that T. gondii oocysts can sporulate and remain viable in seawater for several months.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: . Previously considered an exotic disease, canine leishmaniasis caused by Leishmania infantum has recently been detected within the foxhound population in the United States and parts of Canada. Leishmania infantum is the etiologic agent of visceral leishmaniasis in many areas of the world and dogs are considered a major reservoir host for human Leishmania infections. Human visceral leishmaniasis has recently emerged as an opportunistic infection among individuals co-infected with HIV/AIDS and in persons taking immunosuppressive drugs. We report the isolation of L. infantum from 3 naturally infected foxhounds from Virginia by culture of popliteal lymph node and bone marrow, and the development of an immunohistochemical test to detect the parasite in tissues.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Cell culture infectivity assays can provide an accurate means of detecting viable Cryptosporidium parvum oocysts from environmental samples or to test the effects of various treatments on oocyst infectivity. Cell culture assays can also be used to test candidate chemotherapeutic agents. The use of a human cell line provides a situation close to human infection. The present assay uses an anti-Cryptospordium primary antibody, combined with a biotinylated secondary antibody, and an immunoperoxidase detection system. Cryptosporidium parvum oocysts excysted in vitro when placed on monolayers of HCT-8 cells and developmental stages including schizonts and merozoites were visualized using light microscopy of the immunoperoxidase stained slides and by transmission electron microscopy of infected HCT-8 cell cultures. Because the immunoperoxidase system used gives a permanent preparation, the cell cultures can be retained and examined later. Dose titration of oocysts indicated that as few as 50 inoculated oocysts could be detected. The activity of paromomycin was evaluated in this system and 500 μg/ml produced a 97.8% reduction in infection.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. Toxoplasma gondii infections have been reported in a number of marine mammals. Presently it is not known how these animals acquire T. gondii from their aquatic environment. The eastern oyster, Crassostrea virginica, has been shown to remove Cryptosporidium oocysts from seawater and a similar phenomenon may be occurring with T. gondii oocysts and marine invertebrates. The present study was done to determine if eastern oysters could remove and retain T. gondii oocysts from seawater. Oocysts of the VEG strain of T. gondii (1 × 106 oocysts) were placed in seawater (32 ppt NaCl) containing live eastern oysters. The infected seawater was removed one day postinoculation (PI) and replaced with fresh seawater. Selected oysters were removed at 1, 3 and 6 days PL Hemolymph, gill washes, and oyster tissue were collected separately at each observation time. The oyster tissue was homogenized and all 3 samples fed separately to mice. Toxoplasma gondii positive mice were observed at each time period. The results indicate that T. gondii oocysts can be removed from seawater by eastern oysters and retain their infectivity. Contaminated raw oysters may serve as a source of T. gondii infection for marine mammals and humans.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract. We examined the effects of 5 μg/ml ponazuril treatment on developing tachyzoites of Neospora caninum and merozoites of Sarcocystis neurona to better determine the mode of action of this anticoccidial drug. Both parasites develop asexually by endogenesis. Neospora caninum was selected for study because it develops by endodyogeny, which results in two tachyzoites being produced internally, and S. neurona was selected because it develops by endopolygeny which results in many merozoites being produced internally. Ponazuril inhibited development of N. caninum after approximately 48 h post-exposure. Treated tachyzoites of N. caninum developed vacuoles and underwent degeneration. Ponazuril also inhibited development of merozoites of S. neurona. Treated merozoites and maturing schizonts of S. neurona developed vacuoles and underwent degeneration. The ability of S. neurona schizonts to undergo cytokinesis was inhibited. Our results are discussed in relation to previous ultrastructural research on endogenesis of tachyzoites of Toxoplasma gondii undergoing endodyogeny which indicated that ponazuril induced multinucleate stage formation and inhibited cytokinesis. Ponazuril is believed to act on the apicoplast and our study demonstrates that this agent may express its inhibitory effects in different phenotypic manners on different apicomplexan parasites. The enzyme/enzyme systems that are the inhibitory target of ponazuril may be different in these apicomplexans, or the results of inhibition may affect different pathways downstream of its initial site of action in these parasites.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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