Nucleic acid-amplification testing for hepatitis B in cornea donors

Careful donor selection and implementation of tests of appropriate sensitivity and specificity are of paramount importance for minimizing the risk of transmitting infectious diseases from donors to corneal allograft recipients. Reported cases of viral transmission with corneal grafts are very unusual. Nevertheless potential virus transmission through the engraftment cannot be ruled out. According to European Guideline 2006/17/EC, screening for antibodies for Hepatitis B core antigen (anti HBc) is mandatory, and when this test is positive, some criteria must be established before using corneas. Despite the continuous progress in screening tests, donors carrying an occult hepatitis B infection (OBI) can cause transplant-transmitted hepatitis B. To date, Nucleic Acid Testing (NAT) is not an obligatory assay in corneal tissue setting neither in our country nor in the rest of European countries. Herein, we report three cornea donors that were rejected with the diagnosis of OBI through the testing of sensitive NAT and the serological profile of Hepatitis B virus. The aim of this report is to emphasize the need to include NAT in new reviews of EU Tissues and Cells Directives in order to increase level of security in tissue donation as well as not to reject a high number of donors with isolated profile of anti HBc in geographical areas with high prevalence of Hepatitis B, that could be rejected without a true criterion of Hepatitis B infection.     

The textural discontinuity hypothesis: an exploration at a regional level. Shortened version: exploring Holling's TDH

Dominant physical and biological processes in ecosystems occur at specific scales of space and time. The life‐spans and the life‐spaces (areas used by species over their lifetime) become entrained to operate at similar scales. Because life‐spans and life‐spaces are related to body size, ecosystems display polymodality in body size distributions: Holling's textural discontinuity hypothesis, TDH. Falsification of the TDH requires either changing the frequencies of the dominant processes or changing the species. Both are difficult to achieve for regional‐scale faunas, but the transformation of the terrestrial fauna of New Zealand by humans over the past 800 years provides an opportunity to explore the effect of changing the species. Our analyses of the pre and post first‐contact with humans assemblages show that species body size spectra are polymodal and similar (the spectrum is conservative in shape), both pre‐ and post‐spectra exhibiting three distinct modes, despite significant changes in the taxonomic make‐up of the fauna. Our findings are consistent with the TDH, but not consistent with other known competing explanations. There is also a compelling case that invasions and introductions have been more successful in the body size range that falls between modes. This is also consistent with the TDH, but not necessarily at odds with explanations based on propagule pressure.     

Structural studies of novel glycoconjugates from polymerized allergens (allergoids) and mannans as allergy vaccines

Immunotherapy for treating IgE-mediated allergies requires high doses of the corresponding allergen. This may result in undesired side effects and, to avoid them, hypoallergenic allergens (allergoids) polymerized with glutaraldehyde are commonly used. Targeting allergoids to dendritic cells to enhance cell uptake may result in a more effective immunotherapy. Allergoids coupled to yeast mannan, as source of polymannoses, would be suitable for this purpose, since mannose-binding receptors are expressed on these cells. Conventional conjugation procedures of mannan to proteins use oxidized mannan to release reactive aldehydes able to bind to free amino groups in the protein; yet, allergoids lack these latter because their previous treatment with glutaraldehyde. The aim of this study was to obtain allergoids conjugated to mannan by an alternative approach based on just glutaraldehyde treatment, taking advantage of the mannoprotein bound to the polymannose backbone. Allergoid-mannan glycoconjugates were produced in a single step by treating with glutaraldehyde a defined mixture of allergens derived from Phleum pratense grass pollen and native mannan (non-oxidized) from Saccharomyces cerevisae. Analytical and structural studies, including 2D-DOSY and ¹H-¹³C HSQC nuclear magnetic resonance spectra, demonstrated the feasibility of such an approach. The glycoconjugates obtained were polymers of high molecular weight showing a higher stability than the native allergen or the conventional allergoid without mannan. The allergoid-mannan glycoconjugates were hypoallergenic as detected by the IgE reactivity with sera from grass allergic patients, even with lower reactivity than conventional allergoid without mannan. Thus, stable hypoallergenic allergoids conjugated to mannan suitable for using in immunotherapy can be achieved using glutaraldehyde. In contrast to mannan oxidation, the glutaraldehyde approach allows to preserve mannoses with their native geometry, which may be functionally important for its receptor-mediated recognition.     

Gliding Associated Proteins Play Essential Roles during the Formation of the Inner Membrane Complex of Toxoplasma gondii

The inner membrane complex (IMC) of apicomplexan parasites is a specialised structure localised beneath the parasite’s plasma membrane, and is important for parasite stability and intracellular replication. Furthermore, it serves as an anchor for the myosin A motor complex, termed the glideosome. While the role of this protein complex in parasite motility and host cell invasion has been well described, additional roles during the asexual life cycle are unknown. Here, we demonstrate that core elements of the glideosome, the gliding associated proteins GAP40 and GAP50 as well as members of the GAPM family, have critical roles in the biogenesis of the IMC during intracellular replication. Deletion or disruption of these genes resulted in the rapid collapse of developing parasites after initiation of the cell cycle and led to redistribution of other glideosome components.