Contribution of the antrum and duodenum to circulating forms of gastrin in the dog

Gastrin release was stimulated in four anaesthetized dogs with meat extract and acetylcholine. The different forms of gastrin were analyzed in antral and duodenal mucosa and in blood from antral, duodenal and peripheral veins by use of radioimmunoassay with a region-specific antibody, Sephadex gel filtration, and SDS-gel electrophoresis. The duodenum contributed less than 4% of antral gastrin to circulating gastrin. The molecular forms of antral and duodenal gastrins were similar. On the basis of the electrophoretic results and the properties of the antibody, gastrin in the antral and duodenal veins consisted of a minor fraction of G 17 and a predominant fraction of C-terminal fragments of smaller molecular size. This fraction was even more marked in the peripheral venous circulation. In the peripheral blood, however, not only smaller forms of gastrin were present but also an increasing ratio of big gastrin immunoreactivity. Thus, there is active postsecretory processing of gastrin in the circulation of the anaesthetized dog.     

Quantification of glycated IgG in CHO supernatants: A practical approach

Post-translational, nonenzymatic glycation of monoclonal antibodies (mAbs) in the presence of reducing sugars (in bioprocesses) is a widely known phenomenon, which affects protein heterogeneity and potentially has an impact on quality, safety, and efficacy of the end product. Quantification of individual glycation levels is compulsory for each mAb therapeutically applied in humans. We therefore propose an analytical method for monitoring glycation levels of mAb products during the bioprocess. This is a useful tool for process-design considerations, especially concerning glucose-feed strategies and temperature as major driving factors of protein glycation. In this study, boronate affinity chromatography (BAC) was optimized for determination of the glycation level of mAbs in supernatants. In fact, the complex matrix found in supernatants is an underlying obstacle to use BAC, but with a simple clean-up step, we found that the elution profile could be significantly improved so that qualitative and quantitative determination could be reached. Complementary analytical methods confirmed the performance quality, including the correctness and specificity of the results. For quantitative determination of mAb glycation in supernatants, we established a calibration procedure for the retained mAb peak, identified as glycated antibody monomers. For this approach, an available fully characterized mAb standard, Humira®, was successfully applied, and continuous monitoring of mAbs across three repetitive fed-batch processes was finally performed. With this practical, novel approach, an insight was obtained into glycation levels during bioprocessing, in conjunction with glucose levels and product titer over time, facilitating efficient process development and batch-consistency monitoring.     

Against Fairness

The book, Against Fairness, by philosopher Stephen T. Asma is reviewed. Concepts of favoritism and justice are explored.