A multi-laboratory evaluation of a common in vitro pepsin digestion assay protocol used in assessing the safety of novel proteins.

Rationale. Evaluation of the potential allergenicity of proteins derived from genetically modified foods has involved a weight of evidence approach that incorporates an evaluation of protein digestibility in pepsin. Currently, there is no standardized protocol to assess the digestibility of proteins using simulated gastric fluid. Potential variations in assay parameters include: pH, pepsin purity, pepsin to target protein ratio, target protein purity, and method of detection. The objective was to assess the digestibility of a common set of proteins in nine independent laboratories to determine the reproducibility of the assay when performed using a common protocol. Methods. A single lot of each test protein and pepsin was obtained and distributed to each laboratory. The test proteins consisted of Ara h 2 (a peanut conglutin-like protein), beta-lactoglobulin, bovine serum albumin, concanavalin A, horseradish peroxidase, ovalbumin, ovomucoid, phosphinothricin acetyltransferase, ribulose diphosphate carboxylase, and soybean trypsin inhibitor. A ratio of 10U of pepsin activity/microg test protein was selected for all tests (3:1 pepsin to protein, w:w). Digestions were performed at pH 1.2 and 2.0, with sampling at 0.5, 2, 5, 10, 20, 30, and 60min. Protein digestibility was assessed from stained gels following SDS-PAGE of digestion samples and controls. Results. Results were relatively consistent across laboratories for the full-length proteins. The identification of proteolytic fragments was less consistent, being affected by different fixation and staining methods. Overall, assay pH did not influence the time to disappearance of the full-length protein or protein fragments, however, results across laboratories were more consistent at pH 1.2 (91% agreement) than pH 2.0 (77%). Conclusions. These data demonstrate that this common protocol for evaluating the in vitro digestibility of proteins is reproducible and yields consistent results when performed using the same proteins at different laboratories.

The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours.

Research suggests that aromatherapy massage (AM) is increasingly being used by cancer patients, especially in the palliative care setting, although few studies have assessed its effectiveness. I wanted to find out whether AM reduces anxiety in patients with a primary malignant brain tumour attending their first follow-up appointment after radiotherapy. Eight patients were recruited to the study, which comprised three methods of data collection: the measurement of physical parameters; the completion of Hospital Anxiety and Depression Scales (HADS); and semi-structured interviews. The results from HADS did not show any psychological benefit from AM. However, there was a statistically significant reduction in all four physical parameters, which suggests that AM affects the autonomic nervous system, inducing relaxation. This finding was supported by the patients themselves, all of whom stated during interview that they felt 'relaxed' after AM. Since these patients are faced with limited treatment options and a poor prognosis, this intervention appears to be a good way of offering support and improving quality of life.