Making a blood donation, especially for first-time donors, can be a stressful experience. These feelings of stress may inhibit donors from returning. This paper applies stress theory to this particular problem. The effects of a stress management intervention (the provision of music) and previous donor experience were examined in relation to pre- and post-donation mood, environmental appraisals and coping behaviour. Results indicated that the provision of music had detrimental effects on environmental appraisals for those who have donated up to two times previously, but beneficial effects for those who had donated three times before. These effects were, to an extent, moderated by coping processes but not perceived control. It is recommended that the provision of music is not used as a stress management technique in the context of blood donation.

High level expression of recombinant proteins in bacteria often results in their aggregation into inclusion bodies. Formation of inclusion bodies poses a major bottleneck in high-throughput recovery of recombinant protein. These aggregates have amyloid-like nature and can retain biological activity. Here, effect of expression temperature on the quality of Escherichia coli asparaginase II (a tetrameric protein) inclusion bodies was evaluated. Asparaginase was expressed as inclusion bodies at different temperatures. Purified inclusion bodies were checked for biological activities and analyzed for structural properties in order to establish a structureactivity relationship. Presence of activity in inclusion bodies showed the existence of properly folded asparaginase tetramers. Expression temperature affected the properties of asparaginase inclusion bodies. Inclusion bodies expressed at higher temperatures were characterized by higher biological activity and less amyloid content as evident by Thioflavin T binding and Fourier Transform Infrared (FTIR) spectroscopy. Complex kinetics of proteinase K digestion of asparaginase inclusion bodies expressed at higher temperatures indicate higher extent of conformational heterogeneity in these aggregates.

BackgroundFormation of inclusion bodies poses a major hurdle in recovery of bioactive recombinant protein from Escherichia coli. Urea and guanidine hydrochloride have routinely been used to solubilize inclusion body proteins, but many times result in poor recovery of bioactive protein. High pH buffers, detergents and organic solvents like n-propanol have been successfully used as mild solubilization agents for high throughput recovery of bioactive protein from bacterial inclusion bodies. These mild solubilization agents preserve native-like secondary structures of proteins in inclusion body aggregates and result in improved recovery of bioactive protein as compared to conventional solubilization agents. Here we demonstrate solubilization of human growth hormone inclusion body aggregates using 30 % trifluoroethanol in presence of 3 M urea and its refolding into bioactive form.ResultsHuman growth hormone was expressed in E. coli M15 (pREP) cells in the form of inclusion bodies. Different concentrations of trifluoroethanol with or without addition of low concentration (3 M) of urea were used for solubilization of inclusion body aggregates. Thirty percent trifluoroethanol in combination with 3 M urea was found to be suitable for efficient solubilization of human growth hormone inclusion bodies. Solubilized protein was refolded by dilution and purified by anion exchange and size exclusion chromatography. Purified protein was analyzed for secondary and tertiary structure using different spectroscopic tools and was found to be bioactive by cell proliferation assay. To understand the mechanism of action of trifluoroethanol, secondary and tertiary structure of human growth hormone in trifluoroethanol was compared to that in presence of other denaturants like urea and guanidine hydrochloride. Trifluoroethanol was found to be stabilizing the secondary structure and destabilizing the tertiary structure of protein. Finally, it was observed that trifluoroethanol can be used to solubilize inclusion bodies of a number of proteins.ConclusionsTrifluoroethanol was found to be a suitable mild solubilization agent for bacterial inclusion bodies. Fully functional, bioactive human growth hormone was recovered in high yield from inclusion bodies using trifluoroethanol based solubilization buffer. It was also observed that trifluoroethanol has potential to solubilize inclusion bodies of different proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0504-9) contains supplementary material, which is available to authorized users.

Early referral to mental health professional is required to avoid unnecessary investigations and delay in diagnosis of somatoform disorders in children.