Temporal window of metabolic brain vulnerability to concussion: A pilot H-1 magnetic resonance spectroscopic study in concussed athletes - Part III

OBJECTIVE: In the present study, the occurrence of the tem'! oral window of brain vulnerability was evaluated in concussed athletes by measurinj r, N-acetylaspartate (NAA) using proton magnetic resonance ('H-MR) spectroscopy. METHODS: Thirteen nonprofessional athletes who had a spc t-related concussive head injury were examined for NAA determination by means of IH]MR spectroscopy at 3, 15, and 30 days postinjury. All athletes but three suspended their,hysical activity. Those who continued their training had a second concussive event and I underwent further examination at 45 days from the initial injury. The single case of orle professional boxer, who was studied before the match and 4, 7, 15, and 30 days aft(''!r a knockout, is also presented. Before each magnetic resonance examination, patient, were asked for symptoms of mild traumatic brain injury, including physical, cognitive; lemotional, and sleep disturbances. Data for I H-MR spectroscopy recorded in five n4pal, age-matched, control volunteers, who were previously screened to exclude previolJ1 s head injuries, were used i for comparison. Serniquantitative analysis of NAA relative to creatine (Cr)- and choline (Cho)-containing compounds was performed from proton sl Iectra obtained with a 3-T magnetic resonance system. RESULTS: Regarding the values of the NAA-to-Cr ratio (2.21 ji. 0.11) recorded in control patients, singly concussed athletes, at 3 days after the concuss ion, showed a decrease of 18.5% (1.80 -_ 0.04; P < 0.001). Only a modest 3% recover was observed at 15 days j, r (1.88 0.1; P< 0.001); at 30 days postinjury, the NAA-to-Cr raio was 2.15 -_ 0.1, revealing full metabolic recovery with values not significantly clifflE I rent from those of control patients. These patients declared complete resolution of symj)tctms at the time of the 3day study. The three patients who had a second concussive inj lry before the 15-day study showed an identical decrease of the NAA-to-Cr ratio at 3 da ls (1.78 4- 0.08); however, at 15 days after the second injury, a further diminution of the NAA-to-Cr ratio occurred (1.72 0.07; P < 0.05 with respect to singly concussed athl('!tes). At 30 days, the NAAto-Cr ratio was 1.82 0. 1, and at 45 days postinjury, the NA, I -to-Cr ratio showed com1! plete recovery (2.07 0. 1; not sign if icant with respect to con irol patients). This group of patients declared a complete resolution of symptoms at the ti' I,re of the 30-day study. CONCLUSION: Results of this pilot study carried out in a c( I)hort of singly and doubly I concussed athletes, examined by I H-MR spectroscopy for the I ir NAA cerebral content at different time points after concussive events, demonstrate tha also in humans, concussion opens a temporal window of brain metabolic imbalancejl the closure of which does not coincide with resolution of clinical symptoms. The reco vpry of brain metabolism is I not linearly related to time. A second concussive event prolon ed the time of NAA nor!19 malization by 15 days. Although needing confirmation in a larger group of patients, these 1 5 results show that NAA measurement by 'H-MR spectroscopylis a valid too] in assessing the full cerebral metabolic recovery after concussion, thereb ylsuggesting its use in helpf

Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

In ideal two-stage collimation systems, the secondary collimator–absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator–absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator–absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber

Observation of channeling for 6500 GeV/c protons in the crystal assisted collimation setup for LHC

Two high-accuracy goniometers equipped with two bent silicon crystals were installed in the betatron cleaning insertion of the CERN Large Hadron Collider (LHC) during its long shutdown. First beam tests were recently performed at the LHC with 450 GeV/c and 6500 GeV/c stored proton beams to investigate the feasibility of beam halo collimation assisted by bent crystals. For the first time channeling of 6500 GeV/c protons was observed in a particle accelerator. A strong reduction of beam losses due to nuclear inelastic interactions in the aligned crystal in comparison with its amorphous orientation was detected. The loss reduction value was about 24. Thus, the results show that deflection of particles by a bent crystal due to channeling is effective for this record particle energy

Electroweak parameters of the z0 resonance and the standard model

Contains fulltext : 124399.pdf (publisher's version ) (Open Access

A Measurement of Pi-Polarization at Lep

Contains fulltext : 26223.pdf (publisher's version ) (Open Access

Comparative results on the deflection of positively and negatively charged particles by multiple volume reflections in a multi-strip silicon deflector

Bent silicon crystals in channeling mode are already used for beam extraction and collimation in particle accelerators. Volume reflection of beam particles is more efficient than beam channeling; however, the mean deflection angle is rather small. An experiment on the deflection of a 400 GeV/c proton beam and a 150 GeV/c π– beam at CERN using a multistrip silicon deflector in reflection mode is described. The mean deflection angle of beam particles has been considerably increased due to sequential volume reflections real ized in the deflector. This gives possibility for a successful usage of the multistrip deflectors for beam colli mation in highenergy accelerators. DO