Experimental Investigation of Temperature and Contact Pressure Influence on HFI Welded Joint Properties.

This paper presents an experimental electro-thermo-mechanical simulation of high-frequency induction (HFI) welding to investigate the effect of temperature and contact normal stress on the weld seam quality. Therefore welding experiments at different temperatures and contact pressures are performed using flat specimens of 34MnB5 steel sheet. In order to characterize the weld seam strength of the welded specimens, tensile and bending tests are performed. To obtain a relative weld seam strength, the bending specimens were additionally hardened prior to testing. With the hardened specimens, it can be shown that the weld seam strength increases with increasing temperature and contact normal stress until a kind of plateau is formed where the weld seam strength remains almost constant. In addition to mechanical testing, the influence of the investigated process parameters on the weld seam microstructure is studied metallographically using light optical microscopy, scanning electron microscopy, EBSD and hardness measurements. It is shown that the weld seam strength is related to the amount of oxides in the bonding line.

Immunization with a low-dose replicon DNA vaccine encoding Phl p 5 effectively prevents allergic sensitization.

BACKGROUND: Replicase-based DNA vaccines stimulate T(H)1-biased immune responses at ultralow doses and induce self-removal of transfected cells through apoptosis. Both aspects are important requirements for efficient and safe DNA-based immunotherapy of type I allergies. OBJECTIVE: A Sindbis virus replicon-based DNA vaccine encoding the major timothy grass pollen allergen Phl p 5 was evaluated for its antiallergic potential compared with a conventional DNA vaccine in a BALB/c mouse model of allergy. METHODS: Mice were intradermally prevaccinated with plasmid DNA, followed by sensitization and intranasal allergen provocation with recombinant Phl p 5. In vitro proliferation and cytokine secretion was measured in splenocyte cultures. Distribution of IgG1, IgG2a, and IgE antibody subclasses was determined by means of ELISA. IgE-mediated degranulation was measured with the basophil release assay. Bronchoalveolar lavage fluid was analyzed for eosinophils, IL-4, IL-5, IL-13, and IFN-gamma. Mucus production, inflammatory infiltrates, and epithelial damage were determined in lung sections. RESULTS: Both vaccines induced T(H)1-biased immune responses, resulting in suppression of functional IgE, reduction of eosinophilia in bronchoalveolar lavage fluid, and alleviation of lung pathology. However, immunization with the replicon DNA vaccine elicited these effects at a 100-fold lower dose compared with the conventional DNA vaccine. CONCLUSIONS: The increased immunogenicity of replicon-based DNA vaccines allows for application of extremely low doses, thereby eliminating the concerns associated with conventional DNA vaccines, which have to be administered at milligram amounts to induce immune reactions in human subjects. CLINICAL IMPLICATIONS: Their high safety profile makes replicon-based DNA vaccines promising candidates for treatment of type I allergies in the clinic.

Generation of hypoallergenic DNA vaccines by forced ubiquitination: preventive and therapeutic effects in a mouse model of allergy.

BACKGROUND: Hypoallergenic immunotherapy of type I allergies aims at inducing T-cell immunity while avoiding cross-linking of pre-existing IgE. DNA-based immunotherapy depends on the recruitment of antigen-specific T(H)1 cells and therefore has to provide the whole repertoire of T-cell epitopes. Ubiquitination offers a general approach for the production of hypoallergenic DNA vaccines. OBJECTIVE: A DNA-based vaccine encoding the major birch pollen allergen Bet v 1 stably linked to ubiquitin was evaluated for its antiallergic potential in a BALB/c mouse model of allergy. METHODS: Plasmid DNA was applied to mice before (preventive) or after (therapeutic) sensitization with recombinant Bet v 1. In the preventive setting, mice were exposed to aerosolized allergen in addition. Cytokine production was monitored via ELISPOT and Luminex. IgG(1), IgG(2a), and IgE subclass antibody titers were determined by ELISA. In vitro antigen-specific cross-linking of IgE was measured in a degranulation assay. Bronchoalveolar lavages were analyzed for leukocyte subsets as well as for IFN-gamma and IL-5, and paraffin sections of lungs were examined for mucus production and endothelial damage. RESULTS: Prevaccination with ubiquitinated Bet v 1-stimulated T(H)1-biased immune responses with concomitant suppression of functional IgE, reduction of eosinophil counts in bronchoalveolar lavages, and alleviation of lung pathology, and could also suppress an ongoing IgE response in a therapeutic setting. CONCLUSION: The data clearly demonstrate that hypoallergenic DNA vaccines encoding ubiquitin fusion constructs induce effective antiallergic immune responses. CLINICAL IMPLICATIONS: Ubiquitination of allergen gene vaccines eliminates the risk of IgE cross-linking, thereby meeting the safety requirements for clinical applications.

Isoamyl alcohol-induced morphological change in Saccharomyces cerevisiae involves increases in mitochondria and cell wall chitin content.

Isoamyl alcohol reduced growth and induced filament formation in Saccharomyces cerevisiae. Isoamyl alcohol-induced filamentation was accompanied by an almost threefold greater increase in the specific activity of succinate dehydrogenase than in untreated cells, which suggested that isoamyl alcohol treatment caused the cells to produce more mitochondria than in normal yeast form proliferation. This was supported by measuring the dry weight of purified, isolated mitochondria. Filaments have an increased chitin content which is distributed over the majority of their surface, and is not confined to bud scars and the chitin ring between mother and daughter cells as in yeast-form cells.