Validation of ELISA methods for quantification of the major birch allergen Bet v 1 (BSP090).

To date, the potency of allergen products in Europe is expressed in manufacturer-specific units relative to a product-specific in-house reference. Consequently, cross-product comparability of allergen products from different manufacturers with respect to strength and efficacy is impossible. The Biological Standardisation Programme (BSP) project BSP090 addresses this issue via the establishment of reference standards in conjunction with ELISA methods for the quantification of major allergens in allergen products. Since the initiation of BSP090, the recombinant major allergen Bet v 1 has been adopted by the European Pharmacopoeia Commission as a Chemical Reference Substance (CRS). In parallel, two sandwich ELISA systems for quantification of Bet v 1 were found suitable in preliminary phases of BSP090 to be validated in a large collaborative study. In this study, the candidate ELISA systems were compared with respect to accuracy, precision and variability. Thirteen participating laboratories tested model samples containing the CRS as well as spiked and unspiked birch pollen extracts. Both in pre-testing and in the collaborative study, the 2 candidate ELISA systems confirmed their suitability to quantify recombinant and native Bet v 1. As no clear-cut decision for one of the ELISA systems could be made based on the results of the collaborative study, a post-study testing was performed. Bet v 1 content of 30 birch pollen allergen products was determined in parallel in both ELISA systems. Consequently, 1 candidate ELISA system was selected to be proposed as the future European Pharmacopoeia standard method for Bet v 1 quantification.

[Axillary brachial plexus anesthesia. How many nerve stimulation responses do we look for?]. / Anestesia de plexo braquial por vía axilar. Cuántas respuestas buscamos con neuroestimulación?

OBJECTIVE: To determine whether axillary block with nerve stimulation involving the location of four motor responses is more effective than other techniques using fewer locations, without increasing patient discomfort or the rate of complications. PATIENTS AND METHODS: Prospective, randomized single blind study enrolling 100 patients undergoing orthopedic surgery under axillary block with nerve stimulation. Patients were randomly assigned to five groups of 20 patients: in group A, 4 motor responses were located; in group B three were located (musculocutaneous nerve and two more); in group C two responses, the musculocutaneous nerve and one more; in group D two non-musculocutaneous responses; and in group E only one non-musculocutaneous response was located (medial, cubital or radial). We used 40 ml of 1% mepivacaine. Data collected were location of responses, duration of blockade, adverse events occurring during the technique; level of motor and sensory block; tolerance to the tourniquet; level of patient discomfort; and presence of complications. RESULTS: A full sensory block was achieved for 100% in group A, 90% in group B, 60% in group C, 75% in group D and 40% in group E. Patient discomfort was similar in all groups. One patient continued to suffer postoperative neurologic dysfunction three months after the block. CONCLUSIONS: Locating 4 responses gives the greatest degree of assurance of obtaining full sensory block without increasing patient discomfort or rate of complications.