250 research outputs found

    Verschärfte Institutionenkonkurrenz und neue organisationale Ungleichheiten durch Bachelor- und Master-Studiengänge?

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    "Zentraler Bestandteil des so genannten Bologna-Prozesses ist die Umstellung aufBachelor- und Master-Studiengänge. An diesem Beispiel soll dargestellt werden, wie deutsche Hochschulen die hieraus resultierende Verschärfung der Konkurrenz zwischen unterschiedlichen Anbietern auf dem nachschulischen Bildungsmarkt wahrnehmen, verarbeiten und umsetzen. Zwei empirisch zu überprüfende Vermutungen sind hierbei forschungsleitend: Erstens wird davon ausgegangen, dass sich die Wahrnehmungs- und Reaktionsmuster von Hochschulen nur erfassen lassen, wenn man sie nicht als individuelle Einheiten versteht, sondern als Teil eines umfassenden organisationalen Feldes. Dieses Feld wird durch andere Hochschulen, Akkreditierungsagenturen, staatliche Einrichtungen und Beratungsorganisationen gebildet. Bachelor- und Master-Studiengängestellen dabei im organisationalen Feld 'Hochschulen' ein institutionalisiertes Symbol für Reformfreudigkeit und Innovativität dar. Zweitens ist zu vermuten, dass Universitäten sich nicht abstrakt 'im Wettbewerb' verorten, sondern vielmehr im Rahmen so genannter 'Wettbewerbs-Sets', die nur einen bestimmten Ausschnitt möglicher Konkurrenten umfassen. In diesen 'Wettbewerbs-Sets' spielen ausländische Hochschulen und der 'europäische Bildungsmarkt' einegeringere Rolle als Fachhochschulen, die mit der Umstellung der deutschen Hochschullandschaft auf Bachelor- und Master-Strukturen nun auf demselben Terrain wie Universitäten konkurrieren und so die Institutionenkonkurrenz verschärfen. Eine fürdie nationale Ebene bedeutende Folge des eingeschlagenen Weges in den europäischen Bildungs- und Forschungsraum ist, dass damit die in unterschiedlichen Bildungsabschlüssen zum Ausdruck kommenden traditionellen organisationalen Ungleichheiten innerhalb des deutschen Hochschulsystems aufgehoben werden. Es entstehen jedoch neue Ungleichheiten zwischen Hochschuleinrichtungen, die anders als zuvor nicht in der ständischen Ordnung der Gesellschaft begründet sind, sondern das Ergebnis der unterschiedlichen Umsetzung in der Organisationsumwelt als modern und innovativ geltender Strukturen." (Autorenreferat

    Epidemiological study on factors influencing the occurrence of helminth eggs in horses in Germany based on sent-in diagnostic samples

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    Gastrointestinal nematodes are ubiquitous parasites of grazing equines with Parascaris spp., and strongyles being the most relevant ones regarding the prevalence and potential disease severity. Despite their importance, epidemiological data regarding the presence and egg-shedding intensities of these parasites are scarce. Data from 1067 horse samples collected on German horse farms initially to compare diagnostic methods were used for epidemiological analyses. Due to its higher sensitivity, presence/absence data were based on a combined sedimentation/flotation technique while faecal egg counts were based on Mini-FLOTAC. For strongyles, 46.5% of the samples were positive and the median egg-shedding intensity was 40 (range 5–2590). In multivariate analyses, prevalence and egg-shedding intensity were significantly influenced by season, age group and sample type. The drug used for the last treatment and the number of foals on the yard only affected prevalence while the number of horses on the yard and sex were only significant for egg-shedding intensity. For Parascaris spp., a prevalence of 4.6% and a median egg-shedding intensity of 0 (range 5–905) were observed. In multivariate analyses, the age group, the time since the last anthelmintic treatment, presence and number of foals had significant effects on ascarid prevalence whereas egg-shedding intensity was significantly influenced by age group and season only. Parascaris occurred only on yards with foals, but with an increasing number of foals, Parascaris egg-shedding intensity decreased. Prevalence and egg-shedding intensity were influenced by different but partially overlapping variables for Parascaris and strongyles

    In silico analysis of the cyclophilin repertoire of apicomplexan parasites

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    <p>Abstract</p> <p>Background</p> <p>Cyclophilins (Cyps) are peptidyl <it>cis/trans </it>isomerases implicated in diverse processes such as protein folding, signal transduction, and RNA processing. They are also candidate drug targets, in particular for the immunosuppressant cyclosporine A. In addition, cyclosporine is known to exhibit anti-parasitic effects on a wide range of organisms including several apicomplexa. In order to obtain new non-immunosuppressive drugs targeting apicomplexan cyclophilins, a profound knowledge of the cyclophilin repertoire of this phylum would be necessary.</p> <p>Results</p> <p>BLAST and maximum likelihood analyses identified 16 different cyclophilin subfamilies within the genomes of <it>Cryptosporidium hominis</it>, <it>Toxoplasma gondii</it>, <it>Plasmodium falciparum</it>, <it>Theileria annulata</it>, <it>Theileria parva</it>, and <it>Babesia bovis</it>. In addition to good statistical support from the phylogenetic analysis, these subfamilies are also confirmed by comparison of cyclophilin domain architecture. Within an individual genome, the number of different Cyp genes that could be deduced varies between 7–9 for Cryptosporidia and 14 for <it>T. gondii</it>. Many of the putative apicomplexan cyclophilins are predicted to be nuclear proteins, most of them presumably involved in RNA processing.</p> <p>Conclusion</p> <p>The genomes of apicomplexa harbor a cyclophilin repertoire that is at least as complex as that of most fungi. The identification of Cyp subfamilies that are specific for lower eukaryotes, apicomplexa, or even the genus Plasmodium is of particular interest since these subfamilies are not present in host cells and might therefore represent attractive drug targets.</p

    Efficacy of Cyclooctadepsipeptides and Aminophenylamidines against Larval, Immature and Mature Adult Stages of a Parasitologically Characterized Trichurosis Model in Mice

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    The genus Trichuris includes parasites of major relevance in veterinary and human medicine. Despite serious economic losses and enormous impact on public health, treatment options against whipworms are very limited. Additionally, there is an obvious lack of appropriately characterized experimental infection models. Therefore, a detailed parasitological characterization of a Trichuris muris isolate was performed in C57BL/10 mice. Subsequently, the in vivo efficacies of the aminophenylamidines amidantel, deacylated amidantel (dAMD) and tribendimidine as well as the cyclooctadepsipeptides emodepside and in particular PF1022A were analyzed. This was performed using various administration routes and treatment schemes targeting histotropic and further developed larval as well as immature and mature adult stages. Duration of prepatent period, time-dependent localization of larvae during period of prepatency as well as the duration of patency of the infection were determined before drugs were tested in the characterized trichurosis model. Amidantel showed no effect against mature adult T. muris. Tribendimidine showed significantly higher potency than dAMD after oral treatments (ED50 values of 6.5 vs. 15.1 mg/kg). However, the opposite was found for intraperitoneal treatments (ED50 values of 15.3 vs. 8.3 mg/kg). When emodepside and PF1022A were compared, the latter was significantly less effective against mature adults following intraperitoneal (ED50 values of 6.1 vs. 55.7 mg/kg) or subcutaneous (ED50 values of 15.2 vs. 225.7 mg/kg) administration. Only minimal differences were observed following oral administration (ED50 values of 2.7 vs. 5.2 mg/kg). Triple and most single oral doses with moderate to high dosages of PF1022A showed complete efficacy against histotropic second stage larvae (3 Ă— 100 mg/kg or 1 Ă— 250 mg/kg), further developed larvae (3 Ă— 10 mg/kg or 1 Ă— 100 mg/kg) and immature adults (3 Ă— 10 mg/kg or 1Ă—100 mg/kg). Histotropic first stage larvae were only eliminated after three doses of PF1022A (3 Ă— 100 mg/kg) but not after a single dose. These results indicate that the cyclooctadepsipeptides are a drug class with promising candidates for further evaluation for the treatment of trichurosis of humans and livestock animals in single dose regimens

    Chronic Wasting Due to Liver and Rumen Flukes in Sheep

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    Grazing sheep and goats are constantly exposed to helminth infections in many parts of the world, including several trematode species that causes a range of clinical diseases. The clinical picture of flukes is dependent upon the organs in which they develop and the tissues they damage within the respective organs. Accordingly, infections with the common liver fluke Fasciola hepatica, which, as juvenile worm migrates through the liver parenchyma for several weeks, may be associated with hepatic disorders such as impairment of carbohydrate, protein and fat metabolism, followed by chronic wasting. In contrast, the lancet fluke Dicrocoelium dendriticum, which does not exhibit tissue migration and thus does not lead to major tissue damage and bleeding, also does not lead to significant clinical symptoms. Rumen flukes such as Cotylophoron daubneyi cause catarrhal inflammation during their migration through the intestinal and abomasal epithelium during its juvenile stages. Depending on the infection intensity this may result in a range of clinical symptoms including diarrhoea, inappetence or emaciation. In this review, we aim to provide an update on the current knowledge on flukes particularly concerning the clinical relevance of the most important fluke species in sheep

    Detection of target-site and metabolic resistance to pyrethroids in the bed bug Cimex lectularius in Berlin, Germany

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    Knockdown-resistance (kdr) against pyrethroids in bed bugs (Cimex lectularis) is associated with the presence of several point mutations in the voltage-sensitive sodium channel alpha-subunit gene and/or an increased metabolic detoxification by cytochrome P450 monooxygenases (CYPs). In the present study, pyrosequencing assays were developed to quantify the presence of the kdr substitutions (V419L or L925I substitution) in bed bugs in Berlin, Germany. In 14 of 17 bed bug field strains, pymsequencing revealed the presence of the substitution L925I with allele frequencies between 30% and 100%. One field strain additionally carried the substitution V419L with allele frequencies of 40% in males and 96% in females. In seven of the 17 field strains, mRNA levels of four CYP genes were examined using RT-qPCR. Relative to a susceptible laboratory reference strain, five field strains showed significantly higher mRNA levels of cyp397a1 with 7.1 to 56-fold increases. One of these strains additionally showed a 4.9-fold higher mRNA level of cyp398a1 compared to the reference strain, while cyp4cm1 and cyp6dn1 showed no significant differences. Our findings indicate that multiple resistance mechanisms are present in German C. lectularius populations simultaneously

    Nematode species identification – Current status, challenges and future perspectives for cyathostomin

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    Human and animal health is globally affected by a variety of parasitic helminths. The impact of co-infections and development of anthelmintic resistance requires improved diagnostic tools, especially for parasitic nematodes e.g., to identify resistant species or attribute pathological effects to individual species or particular species combinations. In horses, co-infection with cyathostomins is rather a rule than an exception with typically 5 to 15 species (out of more than 40 described) per individual host. In cyathostomins, reliable morphological species differentiation is currently limited to adults and requires highly specialized expertize while precise morphological identification of eggs and early stage larvae is impossible. The situation is further complicated by a questionable validity of some cyathostomins while others might actually represent cryptic species complexes. Several molecular methods using different target sequences were established to overcome these limitations. For adult worms, PCR followed by sequencing of mitochondrial genes or external or internal ribosomal RNA spacers is suitable to genetically confirm morphological identifications. The most commonly used method to differentiate eggs or larvae is the reverse-line-blot hybridization assay. However, both methods suffer from the fact that target sequences are not available for many species or even that GenBank® entries are unreliable regarding the cyathostomin species. Recent advances in proteomic tools for identification of metazoans including insects and nematodes of the genus Trichinella will be evaluated for suitability to diagnose cyathostomins. Future research should focus on the comparative analysis of morphological, molecular and proteomic data from the same cyathostomin specimen to optimize tools for species-specific identification

    Epidemiology of strongyle nematode infections and first report of benzimidazole resistance in Haemonchus contortus in goats in South Darfur State, Sudan

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    Background Since pastoralists in South Darfur, Sudan, had complained about lack of albendazole (ABZ) efficacy to control nematodes in goats, the frequency of infection with gastrointestinal helminths was studied before in vivo faecal egg count reduction tests (FECRT) were conducted using ABZ orally either at the dose recommended for sheep, 5 mg/kg body weight (bw) or at 10 mg/kg bw. Experiments included goats naturally infected with gastrointestinal nematodes or experimentally infected with local Haemonchus contortus isolates. Three study areas (Nyala, Beleil and Kass) were visited in autumn or winter. Results Out of 478 screened goats, 82.4% were infected with gastrointestinal helminths and 82% were shedding eggs of strongyle nematodes with 90% of the strongyle larvae representing Haemonchus spp. A FECRT using naturally infected goats (n = 225: 71 untreated, 104 and 50 treated with 5 and 10 mg ABZ/kg bw, respectively) detected reduced ABZ efficacy in Nyala and Kass. Paired and unpaired FECRT calculations detected reductions of 72–92% with samples taken at 8 days post treatment with 5 mg ABZ/kg bw and of 85–94% with 10 mg ABZ/kg bw. The FECRT based on day 14 post treatment samples showed reductions of 69–77% with 5 mg/kg and of 75–87% with 10 mg ABZ/kg bw. In Beleil, ABZ efficacy was 95%. In the egg hatch test EC50 values for Nyala and Kass ranged from 0.12–0.24 μg thiabendazole/ml, corresponding to benzimidazole resistant phenotypes. Only Haemonchus spp. larvae were present after treatments in coprocultures. When the efficacy was evaluated experimentally using isolates of H. contortus from Nyala and Kass, the 5 mg ABZ/kg dose revealed reductions of 76–78% on day 8 and of 62–70% on day 14 with the unpaired method. Using 10 mg ABZ/kg, the FECR was still only 77–82%. Conclusions Both, in vivo and in vitro methods detected resistant H. contortus populations in goats from South Darfur State. The time point 14 days post treatment was more sensitive for detection of ABZ resistance than 8 days post treatment. This is the first report on the occurrence of anthelmintic resistance in Sudan confirming that anthelmintic resistance selection is occurring in African subsistence farming systems
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