Host cell protein analysis in therapeutic protein bioprocessing - methods and applications.

The analysis of host cell proteins (HCPs) is one of the most important analytical requirements during bioprocess development of therapeutic moieties. In this review, we focus on the comparison of different methods for the analysis of HCPs and how cell lines, fermentation conditions, and unit operations influence HCP distribution during the process chain. Current guidelines typically require reduction of HCPs to the ppm level, depending on the intended use, the route of administration of the product, and the production system. A range of immunospecific and non-specific methods are available that have been globally accepted by regulatory bodies. Immunospecific methods, such as ELISA, are simple to use in routine analysis and can quantify low levels of HCPs when specific antibodies are available. Non-specific methods are more complex; however, they provide a holistic view of the HCP profile and qualitative information of the composition of HCP in the sample. Different methods for the comparison of bioprocessing strategies during scale-up and purification development are compared herein. The methods include immunospecific methods, such as ELISA, western blot, and threshold, and non-specific methods, such as 2D-DIGE and 2D-HPLC combined with MS.

Changes in vagal tone with posture in asthma are related to changes in ventilatory pattern.

BACKGROUND: Posturally induced changes in minute ventilation in patients may be autonomically driven. This study aimed to test whether changes in autonomic tone with posture differed between normal and asthmatic subjects and whether this related to changes in indices of ventilation. METHODS: Ten patients with type 1 brittle asthma (BA), 10 with non-brittle, severe asthma (SA), 10 with mild asthma (MA) and 10 normal individuals were studied lying flat, at 60 degrees head up tilt and flat again each for 30min, assessing end-tidal CO(2) (ETCO(2)), respiratory rate and autonomic tone by heart rate variability. RESULTS: Parasympathetic tone (as high-frequency [HF] power) fell on tilt in all four groups, all showing increases in LF (low frequency)/HF ratio (sympatho-vagal balance) on tilt (BA, 2.03-4.9; SA, 3.3-8.2; MA, 1.5-4.9; normals, 2.3-6.6). ETCO(2) on tilt fell significantly in all 3 asthma groups (BA, DeltaETCO(2) -0.4, 95% CIs -0.18 to -0.75, P=0.005; SA, -0.7, 95% CIs -0.27 to -1.16, P=0.004; MA, -0.5, 95% CIs -0.14 to -0.78, P=0.01) but not in normals (-0.1, 95% CIs +0.23 to -0.49). The fall in ETCO(2) on tilt correlated with the fall in HF power in all three asthma groups but not in normal subjects. CONCLUSION: Changes in vagal tone posture are seen on tilt in both normal and asthmatic subjects which relate to changes in ETCO(2) only in asthmatic subjects. This provides support for the hypothesis that hyper-ventilatory response to postural change in asthma is autonomically influenced.