Browsing by Author "Lopata, Andreas"

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    Acute and chronic effects of ammonia in the South African abalone, Haliotis midae Linnaeus (Mollusca)
    (2006) Reddy-Lopata, Kasturi; Moloney, Coleen; Cook, Peter; Lopata, Andreas
    Ammonia is the major end-product of protein catabolism in abalone, and is excreted into the surrounding water. Build-up of ammonia in abalone aquaculture systems can reach high toxic levels and impact negatively on farming operations. Ammonia levels therefore have to be regulated. Accurate estimates of toxic un-ionized ammonia (FAN) from the total ammonia nitrogen (TAN) measured by photometer test kits is crucial as inaccuracies could result in major losses of abalone on the farms. The accuracy and applicability of two frequently used photometer test kits (the Nesslers method and the Palintest method) were compared. The calculated TAN concentrations were regressed against the prepared standard ammonia concentrations in seawater for both methods. The predicted slope (β = 1) if the methods were 100% accurate was compared to observed slopes using the Nesslers (β=0.8327) and Palintest (β = 0.7507) methods. Both these test kits underestimated the TAN concentrations, but the Nesslers method was more accurate. Nitrites and nitrates are toxic to abalone at much larger concentrations than ammonia and exist at low concentrations in natural systems, therefore the sensitivity of their tests was not as important. Nitrites and nitrates were monitored using the Ferrous sulphate method and the Cadmium reduction method, respectively.
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    Immune and allergic responses to Anisakis pegreffii, with focus on the roles of IL-4, IL-13 and the IL-4 receptor alpha
    (2007) Nieuwenhuizen, Natalie; Lopata, Andreas; Brombacher, Frank
    The fish-parasitizing nematode Anisakis pegreffii induces gastrointestinal disease and allergy when ingested by humans, and can cause occupational allergy in seafood processing workers. The present study examines immune and allergic responses to A. pegreffii in wildtype and gene deficient mice, with special focus on interleukin(IL)-4, IL-13, and the IL-4 receptor alpha (IL-4Rα). Experimental murine models of Anisakis infection, Anisakis-induced anaphylaxis and Anisakis-induced dermatitis were established in order to gain insight into the immune responses generated against Anisakis and unravel mechanisms of allergic disease.
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    Investigation of immune responses in different mouse models of allergic asthma
    (2008) Kirstein, Frank; Lopata, Andreas; Brombacher, Frank; Horsnell, William
    Allergies are a common chronic disease and considerably decrease the quality of life for affected individuals. Understanding the immune responses during allergic diseases is essential for both diagnosis and the development of effective therapies. The route of sensitisation to allergens is one factor that influences the immune response and the outcome of allergic diseases and both human and animal studies have highlighted IL-4Ra as an important component in the induction of allergy. The aim of this study was to investigate the contributions of the route of sensitisation to allergens with focus on the significance of cell specific expression of IL-4Ra in the onset of allergy. The route of sensitization to Anisakis pegreffii influences the outcome of experimental allergic asthma: Worldwide, increasing numbers of allergies to the fish parasite Anisakis pegreffii are reported. Anisakis can cause allergies after accidental infection of humans and in the occupational environment. Currently it is not clear if different exposure routes to Anisakis affect the development of allergic asthma and if they have an influence on the immune response. To address these questions, the present study investigated immune responses and disease development after Anisakis live infection and after nasal sensitisation in a mouse model of allergic airway disease. We showed that the route of sensitisation influences the outcome of Anisakis pegreffii induced allergic asthma and demonstrated important contributions of IL-4Ra to the underlying immune response. Alternatively activated macrophages are not necessary for the development of experimental allergic lung inflammation: Development of alternatively activated macrophages (AAM) is induced by signals of IL-4Ra. Alternatively activated macrophages (AAM) are a feature of allergic asthma in clinical and experimental investigations but their role in the development of allergy is not defined. To address this, a model of acute allergic asthma was used to compare mice deficient in AAM (LysMcrelL-4Ra-110x mice) with control mice. We found that the presence of AAM at early stages of allergic airway inflammation these cells was not required for the onset of the disease. Smooth muscle IL-4Ra is not required for experimental allergic asthma: In vitro studies have suggested that IL-4Ra signalling on airway smooth muscle cells (ASMC) is critical for airway irrflammation and airway hyperresponsiveness. Using mice deficient for IL-4Ra in ASMC, the in vivo effects of impaired IL-4Ra signalling in ASMC on the outcome of asthmatic disease were investigated. The impairment of IL-4Ro: on SMC had no effect on major aetiological markers of allergic asthma. These findings suggest that IL-4Ra responsiveness in airway SMC during the acute phase of allergic asthma is not critical for the outcome of the disease. Conclusions: The present study showed the importance of the route of sensitisation and IL4Ra in the development of allergy to Anisakis pegreffii. The use of in vivo models of experimental allergic asthma revealed that the route of sensitisation can influence the underlying immune response of the disease. Furthermore, by using mice with cell specific deficiencies in IL-4Ra it was demonstrated that expression of this receptor on smooth muscle cells and macrophages is not essential for the development of acute experimental allergic airway disease, as it has been previously suggested.
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    Investigations of immune responses in different mouse models of allergic asthma
    (2008) Kirstein, Frank; Lopata, Andreas; Brombacher, Frank
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    Molecular characterisation of parvalbumin and analysis of cross-reactivity in five fish species using sera from fish-allergic consumers and occupationally exposed workers
    (2008) Beale, Janine; Lopata, Andreas; Jeebhay, Mohamed
    Parvalbumin, the fish major allergen, accounts for over 95% of clinical symptoms in allergic fish consumers. Importantly, this allergen displays lgE cross-reactivity thus allergic sufferers can exhibit clinical symptoms after the ingestion of non-sesitising fish species. In an occupational setting, fish products have also been shown to cause allergic disease in fish-processing factory workers. Whether parvalbumin is a causative allergen in this occupational environment is unknown. The aim of this study was to evaluate IgE reactivity to parvalbumin and other fish fillet proteins using sera from domestic consumers with ingestion-induced fish allergies and sera from occupationally exposed allergic workers. In addition, cross-reactivity among parvalbumins from five highly consumed fish species in South Africa were assessed by immunoblotting and the most cross-reactive species was characterised further. Pilchard parvalbumin was identified as the most cross-reactive allergen in fish-allergic consumers. The cDNA sequenceß form of pilchard parvalbumin was determined. This is the first time that parvalbumin from the fish order, Clupeiformes, has been characterised and represents a crucual primary step towards the generation of a recombinant form for potential diagnostic and therapeutic use in allergic individuals. Interestingly, sera IgE from fish-processing factory workers displayed no bing to parvalbumin, nor any other fish fillet proteins in immunoblotting. This result has raised several intriguing questions. Namely, does parvalbumin lack the intrinsic features required for eliciting allergic symptoms via inhalation and/or contact, as are primary routes of exposure in workers? Alternatively, could causative occupational allergens that appear to be absent in the fillet of fish occur in the enzyme-rich digestive tract or potentially the skin of fish species? Future studies aim to addess these questions amongst others, which will contribute to preventative and therapeutic strategies of occupational allergies in workers.