Carnosine, oxidative and carbonyl stress, antioxidants, and muscle fiber characteristics of quadriceps muscle of patients with COPD.

Oxidative/carbonyl stress is elevated in lower-limb muscles of patients with chronic obstructive pulmonary disease (COPD). Carnosine is a skeletal muscle antioxidant particularly present in fast-twitch fibers. The aims of the present study were to compare muscle carnosine, oxidative/carbonyl stress, antioxidants, and fiber characteristics between patients with COPD and healthy controls (HCs) and between patients after stratification for airflow limitation (mild/moderate vs. severe/very severe), as well as to investigate correlates of carnosine in patients with COPD. A vastus lateralis muscle biopsy was obtained from 40 patients with stable COPD and 20 age- and sex-matched HCs. Carnosine, oxidative/carbonyl stress, antioxidants, fiber characteristics, quadriceps strength and endurance (QE), V̇o2peak (incremental cycle test), and physical activity (PA) were determined. Patients with COPD had a similar carnosine concentration [4.16 mmol/kg wet weight (WW; SD = 1.93)] to HCs [4.64 mmol/kg WW (SD = 1.71)] and significantly higher percentage of fast-twitch fibers and lower QE, V̇o2peak, and PA versus HCs. Patients with severe/very severe COPD had a 31% lower carnosine concentration [3.24 mmol/kg WW (SD = 1.79); n = 15] versus patients with mild/moderate COPD [4.71 mmol/kg WW (SD = 1.83); n = 25; P = 0.02] and significantly lower V̇o2peak and PA versus patients with mild/moderate COPD. Carnosine correlated significantly with QE (rs = 0.427), V̇o2peak (rs = 0.334), PA (rs = 0.379), and lung function parameters in patients with COPD. In conclusion, despite having the highest proportion of fast-twitch fibers, patients with severe/very severe COPD displayed a 31% lower muscle carnosine concentration compared with patients with mild/moderate COPD. As no other markers of oxidative/carbonyl stress or antioxidants were affected, the observed carnosine deficiency is thought to be a possible first sign of muscle redox balance abnormalities.NEW & NOTEWORTHY Carnosine, particularly present in fast-twitch fibers, was investigated in the quadriceps of patients with chronic obstructive pulmonary disease (COPD). Carnosine concentration was similar between patients with COPD and healthy controls but was 31% lower in patients with severe/very severe COPD, despite their high proportion of fast-twitch fibers, versus patients with mild/moderate COPD. As no other markers of oxidative/carbonyl stress or antioxidants were affected, the observed carnosine deficiency is thought to be a possible first sign of muscle redox balance abnormalities.

French comparison exercise with the rotating neutron spectrometer, 'ROSPEC'.

The French laboratories in charge of 'neutron' dosimetry using the spectrometer 'ROSPEC', formed a working group in 2001. The participants began to study the behaviour of the instrument with a comparison exercise in broad energy neutron fields recommended by the International Organisation for Standardisation (ISO) and available at the LMDN in Cadarache. The complete version of the ROSPEC is made up of six spherical proportional counters fixed to a rotating platform. These counters cover different energy ranges which overlap each other to provide a link between the detectors, within the energy range from thermal neutrons to 4.5 MeV. The irradiation configurations chosen were ISO standard sources (252Cf, (252Cf+D2O)(/Cd), 241Am-Be) and the SIGMA facility. The results show that the 'thermal and epithermal' neutron fluence was widely overestimated by the spectrometer in all configurations.

Inter-laboratory test program (PTI) in 'neutron dosimetry'.

The Laboratory of External Dosimetry Studies and Researches (LRDE), associated laboratory to the Bureau National de Métrologie, is strongly involved in the reference establishment and calibration of instruments in neutron radiation fields provided by 241Am-Be, 252Cf and (252Cf + D2O)/Cd sources. In 1997, on the request of COFRAC, the LRDE has managed an Inter-Laboratory Test Program in 'neutron dosimetry' to compare the different standard calibration methods. The transfer instrument used was a "Harwell Monitor N91". The results of the participant were in good agreement but the associated uncertainties need to be revised by some of laboratories. According to the Mutual Recognition Arrangement signed in 1999, laboratories for metrology will have to assure the traceability of their references. In 2003-2005, the LRDE organises, with National Physical Laboratory (UK) and Physikalisch-Techische Bundesanstalt (Germany), an international comparison in 'neutron dosimetry'. Two transfer instruments, a "2202D" rate metre and a "Harwell Monitor N91", will be sent in turn to the participant laboratories for measurements at their own neutron sources facilities.