Simultaneous measurement of protein-bound 3-chlorotyrosine and homocitrulline by LC-MS/MS after hydrolysis assisted by microwave: application to the study of myeloperoxidase activity during hemodialysis.
; Franck, Thierry ; et al
in Talanta (2012), 99
A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation ... [more ▼]
A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation is not possible, uremia can be reduced by hemodialysis although the repeated interventions have been implicated in loss of renal function, partially as a result of chronic inflammation and/or oxidative stress processes. In this context, it has been suggested that myeloperoxidase (MPO) can contribute to the oxidative stress during hemodialysis and to the cardiovascular risk. Protein damages due to MPO activity have never been assessed during hemodialysis although two of its reaction products, 3-chlorotyrosine and homocitrulline, are of interest. Indeed, the first one is a specific product of MPO activity and the formation of the second one could be catalyzed by MPO. In order to analyze these products in plasma proteins, a total hydrolysis method followed by liquid chromatography mass spectrometry analysis was developed. Different conditions of hydrolysis were tested and the optimized procedure was assessed for complete hydrolysis and artifactual chlorination. Finally, the method was used for analyzing 3-chlorotyrosine and homocitrulline in plasma proteins during a hemodialysis session in fifteen patients and data were related to measurements of MPO concentration and activity. Both increases in MPO activity and protein-bound 3-chlorotyrosine were observed, highlighting the involvement of MPO in oxidative stress during hemodialysis and further demonstrating the link between hemodialysis and cardiovascular diseases. [less ▲]Detailed reference viewed: 14 (0 ULg)
Benefits of napping and an extended duration of recovery sleep on alertness and immune cells after acute sleep restriction.
; ; et al
in Brain, Behavior & Immunity (2011), 25(1), 16-24
Understanding the interactions between sleep and the immune system may offer insight into why short sleep duration has been linked to negative health outcomes. We, therefore, investigated the effects of ... [more ▼]
Understanding the interactions between sleep and the immune system may offer insight into why short sleep duration has been linked to negative health outcomes. We, therefore, investigated the effects of napping and extended recovery sleep after sleep restriction on the immune and inflammatory systems and sleepiness. After a baseline night, healthy young men slept for a 2-h night followed by either a standard 8-h recovery night (n=12), a 30-min nap (at 1 p.m.) in addition to an 8-h recovery night (n=10), or a 10-h extended recovery night (n=9). A control group slept 3 consecutive 8-h nights (n=9). Subjects underwent continuous electroencephalogram polysomnography and blood was sampled every day at 7 a.m. Leukocytes, inflammatory and atherogenesis biomarkers (high-sensitivity C-reactive protein, interleukin-8, myeloperoxidase, fibrinogen and apolipoproteins ApoB/ApoA), sleep patterns and sleepiness were investigated. All parameters remained unchanged in the control group. After sleep restriction, leukocyte and - among leukocyte subsets - neutrophil counts were increased, an effect that persisted after the 8-h recovery sleep, but, in subjects who had a nap or a 10-h recovery sleep, these values returned nearly to baseline. Inflammatory and atherogenesis biomarkers were unchanged except for higher myeloperoxidase levels after sleep restriction. The increased sleepiness after sleep restriction was reversed better in the nap and extended sleep recovery conditions. Saliva cortisol decreased immediately after the nap. Our results indicate that additional recovery sleep after sleep restriction provided by a midday nap prior to recovery sleep or a sleep extended night can improve alertness and return leukocyte counts to baseline values. [less ▲]Detailed reference viewed: 19 (2 ULg)