Molecular Characterization of Recombinant Mus a 5 Allergen from Banana Fruit

Allergy to banana fruit appears to have become an important cause of fruit allergy in Europe. Among five allergens that have been found, beta-1,3-glucanase denoted as Mus a 5 was identified as a candidate allergen for the component-resolved allergy diagnosis of banana allergy. Because of the variations in protein levels in banana fruit, in this study Mus a 5 was produced as a fusion protein with glutathione-S-transferase in Escherichia coli. The recombinant Mus a 5 was purified under native conditions by a combination of affinity, ion-exchange, and reversed phase chromatography. N-terminal sequence was confirmed by Edman degradation and 55 % of the primary structure was identified by mass fingerprint, while the secondary structure was assessed by circular dichroism spectroscopy. IgG reactivity of recombinant protein was shown in 2-D immunoblot with anti-Mus a 5 antibodies, while IgG and IgE binding to natural Mus a 5 was inhibited with the recombinant Mus a 5 in immunoblot inhibition test. IgE reactivity of recombinant Mus a 5 was shown in ELISA within a group of ten persons sensitized to banana fruit. Recombinant Mus a 5 is a novel reagent suitable for the component-resolved allergy diagnosis of banana allergy

Fabrication Technology for Efficient High Power Silicon Carbide Bipolar Junction Transistors

The superior characteristics of Silicon Carbide as a wide band gap semiconductor have motivated many industrial and non-industrial research groups to consider SiC for the next generations of high power semiconductor devices. The SiC Bipolar Junction Transistor (BJT) is one candidate for high power applications due to its low on-state power loss and fast switching capability. However, to compete with other switching devices such as Field Effect Transistors (FETs) or IGBTs, it is necessary for a power SiC BJT to provide a high current gain to reduce the power required from the drive circuit. In this thesis implantation free 4H-SiC BJTs with linearly graded base layer have been demonstrated with common-emitter current gain of 50 and open-base breakdown voltage of 2700 V. Also an efficient junction termination extension (JTE) with 80% of theoretical parallel-plane breakdown voltage was analyzed by fabrication of high voltage PiN diodes to achieve an optimum dose of remaining JTE charge. Surface passivation of 4H-SiC BJT is an essential factor for efficient power BJTs. Therefore different passivation techniques were compared and showed that around 60% higher maximum current gain can be achieved by a newsurface passivation layer with low interface trap density that consists of PECVD oxide followed by post-deposition oxide anneal in N2O ambient. This surface passivation along with doublezone JTE were used for fabrication of high power BJTs that result in successful demonstration of 2800 V breakdown voltage for small area (0.3 × 0.3 mm) and large area (1.8 × 1.8 mm) BJTs with a maximum dc current gain of 55 and 52, respectively. The small area BJT showed RON = 4mΩcm2, while for the large are BJT RON = 6.8 mΩcm2. Finally, a Darlington transistor with a maximum current gain of 2900 at room temperature and 640 at 200 °C is reported. The high current gain of the Darlington transistor is achieved by optimum design for the ratio of the active area of the driver BJT to the output BJT.QC 2011021

Estimating the Risk of Severe Peanut Allergy Using Clinical Background and IgE Sensitization Profiles

BACKGROUND: It is not well-understood why symptom severity varies between patients with peanut allergy (PA). OBJECTIVE: To gain insight into the clinical profile of subjects with mild-to-moderate and severe PA, and investigate individual and collective predictive accuracy of clinical background and IgE to peanut extract and components for PA severity. METHODS: Data on demographics, patient history and sensitization at extract and component level of 393 patients with probable PA (symptoms ≤ 2 h + IgE sensitization) from 12 EuroPrevall centers were analyzed. Univariable and penalized multivariable regression analyses were used to evaluate risk factors and biomarkers for severity. RESULTS: Female sex, age at onset of PA, symptoms elicited by skin contact with peanut, family atopy, atopic dermatitis, house dust mite and latex allergy were independently associated with severe PA; birch pollen allergy with mild-to-moderate PA. The cross-validated AUC of all clinical background determinants combined (0.74) was significantly larger than the AUC of tests for sensitization to extract (0.63) or peanut components (0.54–0.64). Although larger skin prick test wheal size, and higher IgE to peanut extract, Ara h 1 and Ara h 2/6, were associated with severe PA, and higher IgE to Ara h 8 with mild-to-moderate PA, addition of these measurements of sensitization to the clinical background model did not significantly improve the AUC. CONCLUSIONS: Models combining clinical characteristics and IgE sensitization patterns can help establish the risk of severe reactions for peanut allergic patients, but clinical background determinants are most valuable for predicting severity of probable PA in an individual patient