Search

Aim: A nested case-control discovery study was undertaken to test whether information within the serum peptidome can improve on the utility of CA125 for early ovarian cancer detection., Materials and Methods: High-throughput matrix-assisted laser desorption ionisation mass spectrometry (MALDI-MS) was used to profile 295 serum samples from women pre-dating their ovarian cancer diagnosis and from 585 matched control samples. Classification rules incorporating CA125 and MS peak intensities were tested for discriminating ability., Results: Two peaks were found which in combination with CA125 discriminated cases from controls up to 15 and 11 months before diagnosis, respectively, and earlier than using CA125 alone. One peak was identified as connective tissue-activating peptide III (CTAPIII), whilst the other was putatively identified as platelet factor 4 (PF4). ELISA data supported the down-regulation of PF4 in early cancer cases., Conclusion: Serum peptide information with CA125 improves lead time for early detection of ovarian cancer. The candidate markers are platelet-derived chemokines, suggesting a link between platelet function and tumour development.

Blood represents a convenient diagnostic specimen for clinical analysis. Serum metabolites and peptides have the potential to serve as reliable indicators of progression from a normal to a diseased state. However, the presence of salts, lipids and high concentrations of protein in blood serum can adversely affect its mass spectrometric profiling, as all of these moieties can hinder the ionisation and detection of diagnostic biomarkers. Several pre-fractionation strategies using chromatographic adsorbents have been employed to desalt samples and remove abundant proteins such as albumin and immunoglobulin. As an alternative to multi-stage fractionation chromatography, we describe in this practical review the adaptation and validation of a simple and fast solid-phase extraction technique using ZipTips. The protocol allows for the purification and concentration of peptides in a few, mostly automated steps, prior to spectral biomarker pattern diagnostics using MALDI MS and MS/MS. It has the added advantages of being suitable for use in a high-throughput and potentially clinical environment, only requiring a few microlitres of serum. We have evaluated, optimised, and standardised a number of analytical parameters ranging from serum storage and handling to automated peptide extraction, crystallisation, spectral acquisition, and signal processing. Using standardised protocols the average CV of serum profiles within- and between-run replicates has been evaluated and found to be around 10 % based on the variability of all detected peaks (more than 100 peaks per profile). The results show that this easy and fast method of using ZipTips, tested over a whole year, is more reproducible and more suitable for serum profile screening than magnetic bead-based methodologies which show higher variability and higher rates of rejected, low-quality spectra upon applying strict data quality control filters.

Objectives: Peptide tyrosine tyrosine (PYY) exists as two species, PYY1‐36 and PYY3‐36, with distinct effects on insulin secretion and appetite regulation. The detailed effects of bariatric surgery on PYY1‐36 and PYY3‐36 secretion are not known as previous studies have used nonspecific immunoassays to measure total PYY. Our objective was to characterize the effect of sleeve gastrectomy (SG) and Roux‐en‐Y gastric bypass (RYGB) on fasting and postprandial PYY1‐36 and PYY3‐36 secretion using a newly developed liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) assay. Design and Subjects: Observational study in 10 healthy nonobese volunteers and 30 participants with obesity who underwent RYGB (n = 24) or SG (n = 6) at the Imperial Weight Centre [NCT01945840]. Participants were studied using a standardized mixed meal test (MMT) before and 1 year after surgery. The outcome measures were PYY1‐36 and PYY3‐36 concentrations. Results: Presurgery, the fasting and postprandial levels of PYY1‐36 and PYY3‐36 were low, with minimal responses to the MMT, and these did not differ from healthy nonobese volunteers. The postprandial secretion of both PYY1‐36 and PYY3‐36 at 1 year was amplified after RYGB, but not SG, with the response being significantly higher in RYGB compared with SG. Conclusions: There appears to be no difference in PYY secretion between nonobese and obese volunteers at baseline. At 1 year after surgery, RYGB, but not SG, is associated with increased postprandial secretion of PYY1‐36 and PYY3‐36, which may account for long‐term differences in efficacy and adverse effects between the two types of surgery. [ABSTRACT FROM AUTHOR]