Publications (19) View all
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Article: The spatial organization and extraction of the wall-forming bodies of Eimeria maxima.
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ABSTRACT: SUMMARY Eimeria maxima has been used as a model apicomplexan parasite to study sexual stage development and oocyst wall formation. A complete understanding of the wall's biochemical and biophysical properties is of great interest in research on all apicomplexan parasites. Purified gametocytes, zygotes and oocysts were analysed by three-dimensional confocal microscopy, and wide-field fluorescent microscopy was used to investigate the appearance and spatial organization of the 2 types of wall-forming bodies (WFBs). In addition, a variety of staining procedures and immunoassays were used to assess the biosynthesis, metabolic activity, intactness and molecular composition of the WFBs in situ. WFBs were extracted from gametocytes/zygotes and their composition was assessed by microscopy and SDS-PAGE analysis. It was concluded that isolated gametocytes are intact and metabolically active. Additionally, it was observed that the Type 1 WFBs are aligned at the periphery of the parasite and fuse together producing neutral lipid rich patches that appear to be inserted into the space between 2 parasite-specific membranes. Finally, it was shown that the WFBs extracted from purified gametocytes had the same shape, size and staining properties as those observed in situ, and contained the major glycoprotein antigens known to be present in these organelles.Parasitology 06/2013; 140(7):876-87. · 2.96 Impact Factor -
Article: Comparison of protective immune responses to apicomplexan parasites.
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ABSTRACT: Members of the phylum Apicomplexa, which includes the species Plasmodium, Eimeria, Toxoplasma, and Babesia amongst others, are the most successful intracellular pathogens known to humankind. The widespread acquisition of antimicrobial resistance to most drugs used to date has sparked a great deal of research and commercial interest in the development of vaccines as alternative control strategies. A few antigens from the asexual and sexual stages of apicomplexan development have been identified and their genes characterised; however, the fine cellular and molecular details of the effector mechanisms crucial for parasite inhibition and stimulation of protective immunity are still not entirely understood. This paper provides an overview of what is currently known about the protective immune response against the various types of apicomplexan parasites and focuses mainly on the similarities of these pathogens and their host interaction. Finally, the evolutionary relationships of these parasites and their hosts, as well as the modulation of immune functions that are critical in determining the outcome of the infection by these pathogenic organisms, are discussed.Journal of Parasitology Research 01/2012; 2012:852591. -
Article: Sonographic upper gastrointestinal series in the vomiting infant: how we do it.
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ABSTRACT: Sonography (ultrasound) is used routinely to assess an infant with nonbilious projectile emesis. Fluoroscopic upper gastrointestinal (UGI) series has been the standard method to evaluate infants with bilious emesis. We use sonographic UGI routinely to assess infants with nonbilious emesis as well as infants with bilious emesis. This essay illustrates our technique, the results obtained using this technique for normal anatomy, and the commonly encountered pathology.Journal of clinical imaging science. 01/2011; 1:19. -
Article: Characterisation of an immunodominant, high molecular weight glycoprotein on the surface of infectious Neoparamoeba spp., causative agent of amoebic gill disease (AGD) in Atlantic salmon.
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ABSTRACT: Amoebic gill disease can be experimentally induced by the exposure of salmonids to Neoparamoeba spp. freshly isolated from infected fish, while cultured amoebae are non-infective. Results from our previous work suggested that one key difference between infectious and non-infectious Neoparamoeba were the highly glycosylated molecules in the glycocalyx. To characterise these surface glycans or glycoproteins we used a monoclonal antibody (mAb 44C12) specific to a surface molecule unique to infective parasites. This mAb recognised a carbohydrate epitope on a high molecular weight antigen (HMWA) that make up 15-19% of the total protein in a soluble extract of infectious parasites. The HMWA consisted of at least four glycoprotein subunits of molecular weight (MW) greater than 150 kDa that form disulfide-linked complexes of MW greater than 600 kDa. Chemical deglycosylation yielded at least four protein bands of approximate MW 46, 34, 28 and 18 kDA. While a similar HMWA complex was present in non-infective parasites, the glycoprotein subunits were of lower MW and exhibited differences in glycosylation. The four glycoproteins subunits recognised by mAb 44C12 were resistant to degradation by PNGase F, PNGase A, O-glycosidase plus β-1, 4-galactosidase, β-N-acetylglucosaminidase and neuraminidase. The major monosaccharides in the HMWA from infectious parasites were rhamnose, fucose, galactose, and mannose while sialic acids were absent. The carbohydrate portion constituted more than 90% of the total weight of the HMWA from infectious Neoparamoeba spp. Preliminary results indicate that immunisation of salmon with HMWA does not lead to protection against challenge infection; rather it may even have an immunosuppressive effect.Fish & Shellfish Immunology 12/2010; 29(6):946-55. · 3.32 Impact Factor -
Article: Role of antibody in immunity and control of chicken coccidiosis.
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ABSTRACT: Research has been carried out worldwide to try to elucidate the mechanism of protective immunity against coccidiosis. It was concluded from early studies that cellular immunity is the key to protection against Eimeria, whereas humoral immunity plays a very minor role in resistance against infection. By contrast, other studies have pointed towards the ability of antibody to block parasite invasion, development and transmission and to provide passive and maternal immunity against challenge infection. Herein, recent results demonstrate the ability of antibodies (raised by live immunization or against purified stage-specific Eimeria antigens) to inhibit parasite development in vitro and in vivo and readdress the question of the role of antibody in protection against coccidiosis.Trends in Parasitology 05/2010; 26(8):382-7. · 5.14 Impact Factor
