Development of novel mass spectrometry methodology to detect post-translational modifications in oxidative stress and disease

This paper presented at the European Meeting of the Society-for-Free-Radical-Research-Europe 2007, discusses the development of novel mass spectrometry methodology to detect post-translational modifications in oxidative stress and disease.

Mapping nitro-tyrosine modifications in fibrinogen by mass spectrometry as a biomarker for inflammatory disease

There is a growing awareness that inflammatory diseases have an oxidative pathology, which can result in specific oxidation of amino acids within proteins. It is known that patients with inflammatory disease have higher levels of plasma protein nitro-tyrosine than healthy controls. Fibrinogen is an abundant plasma protein, highly susceptible to such oxidative modifications, and is therefore a potential marker for oxidative protein damage. The aim of this study was to map tyrosine nitration in fibrinogen under oxidative conditions and identify susceptible residues. Fibrinogen was oxidised with 0.25mM and 1mM SIN-1, a peroxynitrite generator, and methionine was used to quench excess oxidant in the samples. The carbonyl assay was used to confirm oxidation in the samples. The carbonyl levels were 2.3, 8.72 and 11.5nmol/mg protein in 0, 0.25mM and 1mM SIN-1 samples respectively. The samples were run on a SDS-PAGE gel and tryptically digested before analysis by HPLC MS-MS. All 3 chains of fibrinogen were observed for all treatment conditions. The overall sequence coverage for fibrinogen determined by Mascot was between 60-75%. The oxidised samples showed increases in oxidative modifications in both alpha and beta chains, commonly methionine sulfoxide and tyrosine nitration, correlating with increasing SIN-1 treatment. Tyrosines that were most susceptible were Tyr135 (tryptic peptide YLQEIYNSNNQK) and Tyr277 (tryptic peptide GGSTSYGTGSETESPR), but several other nitrated tyrosines were also identified with high confidence. Identification of these susceptible peptides will allow design of sequences-specific biomarkers of oxidative and nitrative damage to plasma protein in inflammatory conditions.

Usual medical treatments or levonorgestrel-IUS for women with heavy menstrual bleeding:long-term randomised pragmatic trial in primary care

Background: Heavy menstrual bleeding (HMB) is a common, chronic problem affecting women and health services. However, long-term evidence on treatment in primary care is lacking. Aim: To assess the effectiveness of commencing the levonorgestrel-releasing intrauterine system (LNG-IUS) or usual medical treatments for women presenting with HMB in general practice. Design and setting: A pragmatic, multicentre, parallel, open-label, long term, randomised controlled trial in 63 primary care practices across the English Midlands. Method: In total, 571 women aged 25–50 years, with HMB were randomised to LNG-IUS or usual medical treatment (tranexamic/mefenamic acid, combined oestrogen–progestogen, or progesterone alone). The primary outcome was the patient reported Menorrhagia Multi-Attribute Scale (MMAS, measuring effect of HMB on practical difficulties, social life, psychological and physical health, and work and family life; scores from 0 to 100). Secondary outcomes included surgical intervention (endometrial ablation/hysterectomy), general quality of life, sexual activity, and safety. Results: At 5 years post-randomisation, 424 (74%) women provided data. While the difference between LNG-IUS and usual treatment groups was not significant (3.9 points; 95% confidence interval = −0.6 to 8.3; P = 0.09), MMAS scores improved significantly in both groups from baseline (mean increase, 44.9 and 43.4 points, respectively; P<0.001 for both comparisons). Rates of surgical intervention were low in both groups (surgery-free survival was 80% and 77%; hazard ratio 0.90; 95% CI = 0.62 to 1.31; P = 0.6). There was no difference in generic quality of life, sexual activity scores, or serious adverse events. Conclusion: Large improvements in symptom relief across both groups show treatment for HMB can be successfully initiated with long-term benefit and with only modest need for surgery.