Cephalosporium stripe of wheat (Triticum aestivum), caused by the soilborne fungus Cephalosporium gramineum, results in significant yield reductions in dryland winter wheat crops of the U.S. Pacific Northwest. The development of resistant cultivars offers the best hope for disease control. Breeding for resistance is hampered by the long trial times inherent in screening adult plants, and by cultivar x environment interactions in field tests. The principal objective of this research was to develop and test a procedure for screening wheat seedlings in controlled environments for resistance to Cephalosporium stripe. Wheat seedlings were raised hydroponically in growth chambers, and the fungus was increased in large fermentation tanks. The seedlings were inoculated at about 12 days post-germination. Disease severity was assessed approximately seven days later using a chlorophyll meter to measure the symptoms of chlorosis and striping. In three trials, five soft white cultivars from the Pacific Northwest and four hard red cultivars from the Southern Great Plains with known levels of field resistance were tested with a Pacific Northwest fungal isolate. With one exception, chlorophyll readings ordered the cultivars appropriately, with moderately resistant cultivars ranking above susceptible cultivars. Three other moderately resistant cultivars from the Pacific Northwest also appeared in one or two trials, and were ranked properly by chlorophyll level. Chlorophyll levels of uninoculated plants were assayed to determine if differences in chlorophyll content were innate in the cultivars. The chlorophyll levels of uninoculated and inoculated seedling treatments were only significantly correlated when the cultivar Madsen, which ranks high both in resistance and in chlorophyll content, was included. In adult plants, flag-leaf chlorophyll level corresponded to intensity of Cephalosporium stripe symptoms where disease was present, and was independent of known field resistance in undiseased cultivars. The seedling screening technique was used to investigate pathogenic variability in C. gramineum. In two experiments, a total of eight cultivars from the Pacific Northwest and the Southern Great Plains were tested with three fungal isolates from each region. No evidence of virulence/vertical resistance was found. There was also no significant adaptation of isolates to greater virulence on cultivars from the same region. / Graduation date: 1998

This master’s thesis deals with high-alloyed Ni-Resist cast irons and their properties. The theoretical part describes their chemical composition and individual elements from which are these cast irons composed, their characteristic properties and examples of use in practice. Furthermore, the work focuses on the wear of materials, especially on abrasive wear, because Ni-Resist casts iron exhibit a number of specific properties, such as corrosion resistance, refractoriness and heat resistance and also abrasion resistance, on which is this thesis focused. Attention is also paid to other abrasion resistant materials, because specimens from different materials are compared in the practical part in order to find a more suitable material for the production of plate castings into the shakeouts.

Efter upptäckten av penicillinet observerades en ökad resistens hos S. aureus vilket ledde till att alla stammar ansågs vara resistenta. Dock har många stammar enligt senare studier visat sig vara känsliga vilket har öppnat upp möjlighet att åter använda benzylpenicillin som ett behandlingsalternativ eftersom det kan ges i lägre koncentration jämfört med andra alternativ. Metoden för att upptäcka penicillinresistens hos S. aureus enligt EUCAST har bedömts svår att tillämpa på grund av subjektivitet vid bedömning av zonkanten. Studiens syfte var att utvärdera metoden för senare implementering på Klinisk Mikrobiologi Unilabs i Skövde. Metodens användbarhet utvärderades genom resistensbestämning av en referensstam samt tio stammar från ett referenslaboratorium för EUCAST. Bedömningen av de tio stammarna från referenslaboratoriet stämde vid jämförelse överens med deras resultat förutom för en stam som bedömdes som resistent i stället för känslig. Repeterbarheten var hög då ingen skillnad (p=0,156) uppvisades för referensstammen.  Resultatet tyder på att det kan vara svårt att göra en korrekt tolkning av zonkantens utseende då det är en subjektiv bedömning. För att uppnå en högre säkerhet kan det vara fördelaktigt att mer än en person gör en bedömning. Slutsatsen var att metoden kan implementeras på laboratoriet. / Following the discovery of penicillin, resistance rates increased until all strains of S. aureus were considered resistant. Recent studies have shown that many strains are susceptible, making it possible to again use penicillin as an alternative for treatment since it can be used in lower concentrations compared to alternatives. The EUCAST method for discovering penicillin resistance in S. aureus has been judged difficult due to the subjectiveness of assessing the zone edge. The aim of this study was to evaluate the method to implement it in the Section for Clinical Microbiology Unilabs Skövde. The useability of the method was evaluated by resistance testing of a reference strain and ten strains from a EUCAST reference laboratory. The assessment of the strains from the reference laboratory equaled their results except for one strain that was assessed resistant rather than sensitive. The repeatability was high since no difference (p=0,156) was found for the reference strain. The results show how difficult it is to correctly assess the zone edge due to its subjectiveness. It could be beneficial with more than one person assessing the zone edge to achieve a higher security. In conclusion the method is possible to implement in the laboratory.

Thesis (MScMedSc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: An important next step to Tuberculosis control relies on the translation of basic science and modern diagnostic techniques into primary health care clinics. These assays must be rapid, inexpensive, interpretation of results must be easy and they must be simple so that a healthcare worker with limited training can perform the tests under safe conditions. This study consists of four aims. The first aim was to develop a methodology to sterilize sputum specimens for rapid TB diagnosis and drug resistance testing. Candidate bactericides were identified from the literature, and tested for their bactericidal activity in Mycobacterium tuberculosis. We identified ultraseptin®aktiv as a powerful bactericidal agent which sterilizes sputum specimens for subsequent safe handling prior to light emitting diode microscopy and it also provides a DNA template for PCR-based tests. An algorithm has been proposed for the processing of specimens and rapid diagnosis of TB and drug resistant TB while patients wait for results. Recently, the World Health Organization has endorsed the MTBDRplus test for diagnosis of TB and drug resistant TB. However genotypic tests may have more problems than anticipated. With the HIV pandemic, an increase of non-tuberculous mycobacteria has been reported. The sensitivity of genotypic tests in specimens with underlying non-tuberculous mycobacterial species therefore requires further evaluation. This study therefore also aimed at determining the reliability of the MTBDRplus assay for detection of drug resistant TB where non-tuberculous bacterial load is high. Clinically relevant non-tuberculous mycobacterium DNA and DNA from a multi-drug resistant TB isolate were obtained. Ratios of the different NTM with the MDR-TB DNA were made and subjected to the MTBDRplus assay. Known mix NTM and TB infected clinical isolates and sputum sediments were also evaluated for TB and drug resistance detection on the MTBDRplus assay. Under these conditions, this study provides evidence that the MTBDRplus test cannot reliably detect TB and drug resistance TB in specimens with underlying non-tuberculous mycobacteria. Thirdly, to evaluate the sensitivity of the MTBDRplus assay for detecting drug resistance in hetero-resistant isolates, ratios were made using purified DNA from an MDR and pan-susceptible TB isolate. The MTBDRplus assay was then performed on the different ratios. We report that the MTBDRplus assay can efficiently detect wild type DNA in genes associated with resistance during the early evolution of drug resistance. However, in the later stage during treatment when both the wild type and mutants are present, the detection limit for the mutant DNA was 1:55. Due to these results, the MTBDRplus assay should still be further improved or other tests should be developed to address these limitations. And finally to combat cross amplicon contamination during the final steps of genotypic detection with the MTBDRplus assay, a proof of concept for a patentable closed tube line probe device was proposed on the 4th aim. This device can be improved to enable automated drug resistance genotyping of multiple specimens. The results of this study highlight the need for a sensitive inexpensive point of care drug resistance test that does not require intensive training. / AFRIKAANSE OPSOMMING: 'n Belangrike volgende stap om Tuberkulose te beheer is om basiese wetenskap resultate te gebruik sodat moderne diagnose tegnieke ontwikkel kan word wat in primêre gesondheidsorg klinieke toegepas kan word. Hierdie toetse moet vinnig, goedkoop, en die interpretasie van resultate moet maklik wees. Die toetse moet eenvoudig wees sodat 'n gesondheidswerker met beperkte opleiding die toetse onder veilige omstandighede kan uitvoer. Hierdie studie bestaan uit vier doelwitte, waarvan die eerste was om 'n metode te ontwikkel vir die sterilisasie van sputum monsters vir vinnige TB diagnose en die toesting van middelweerstandigheid. Kandidaat kiemdodende middels was geïdentifiseer vanaf die literatuur en die middels se kiekdodende aktiviteit was getoets op Mycobacterium tuberculosis. Ons het ultraseptin®aktiv geïdentifiseer as 'n kragtige kiemdodende middel wat bakteria in sputum monsters steriliseer vir veilige hantering voordat diagnose met 'n lig uitstralende diode mikroskopie gedoen kan word. Hierdie behandeling met ultraseptin®aktiv bied ook 'n DNA templaat vir PCR-gebaseerde toetse. 'n Algoritme is voorgestel vir die hantering van monsters en die vinnige diagnose van sensitiewe- en middel weerstandige Tuberkulose terwyl die pasiënte by die kliniek wag vir die resultate. Onlangs het die Wêreld Gesondheid Organisasie die genotipiese MTBDRplus toets vir die diagnose van Tuberkulose en middel-weerstandige Tuberkulose onderskryf. Hierdie toets word tans op groot skaal in Suid Afrika gebruik. Dit kan egter wees dat genotipiese toetse baie meer probleme kan he as wat aanvanklik verwag is. Die HIV pandemie gaan toenemend gepaard met n toename van nie-tuberkulose mycobacteria. Die sensitiwiteit van genotipiese toetse op monsters met onderliggende nie-tuberkulose mikobakteriese spesies vereis dus verdere evaluasie. Die doel van hierdie studie was ook om die betroubaarheid van die MTBDRplus-toets te bepaal vir die opsporing van middelweerstandige TB waar die nie-tuberkulose bakteriële lading hoog is. DNA van kliniese relevante nie-tuberkulose mikobakteria en multi-middelweerstige TB isolate was bekom. Verskillende verdunnigs van die spesifieke NTM DNA te same met die van MDR-TB DNA is gemaak en onderwerp aan die MTBDRplus toets. Bekende gemengde NTM- en TB geïnfekteerde kliniese isolate en sputum sedimente was ook geevalueer vir die opsporing van TB en middel weerstandigheid met die MTBDRplus toets. Hierdie studie verskaf bewyse dat die MTBDRplus toets nie betroubaar is met die diagnose van sensitiewe- en middel weerstandige Tuberkulose in monsters met onderliggende nie-tuberkulose mycobacteria nie. Verskillende verdunnings van gesuiwerde DNA van MDR en pan-sensitiewe TB isolate is gemaak om die sensitiwiteit van die MTBDRplus toets vir die opsporing van middelweerstandigheid te bepaal. Die MDRDRplus toets is gebruik met hierdie verdunnings. Resultate in hierdie studie toon dat die MTBDRplus toets effektief is met die identifisering van wilde-tipe DNA (dit beteken middel sensitief) in gene wat geassosieer word met middel weerstandigheid gedurende die vroeë ontwikkeling van weerstandigheid. Hier teenoor toon die resultate dat in die later stadium tydens behandeling, wanneer beide die wilde-tipe (sensitief) en mutante DNA (weerstandig) teenwoordig is, is die opsporingslimiet vir die mutante DNA maar 1:55. As gevolg van hierdie resultate raai ons aan dat die MTBDRplus toets nog verder verbeter moet word of dat ander toetse ontwikkel moet word om hierdie beperkinge aan te spreek. Amplikon kruiskontaminasie kan n groot impak hê op die betroubaarheid van enige genotipiese diagnostiese toets. Die finale stappe van MTBDRplus toets behels die gebruik van 'n oop sisteem sodat kontaminasie maklik kan plaasvind. In die 4de doewit 'n konsep vir 'n patenteerbare geslotebuis toestel ontwikkel en die resultate het getoon dat kontaminasie suksesvol uitgeskakel kan word. Hierdie toestel kan verbeter na 'n outomatiese apparaat verbeter word sodat die module genotipering van verskeie monsters moontlik kan maak. Die resultate van hierdie studie beklemtoon die noodsaaklikheid van 'n sensitiewe goedkoop “point of care” diagnostiese toets wat nie intensiewe opleiding benodig nie. / Medical Research Council of South Africa / University of Stellenbosch, Dept. of Molecular Biology and Human Genetics