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Background: Among transcranial electric stimulation (tES) parameters, personalizing the electrode geometry might help overcome the individual variability of the induced effects., Objective/hypothesis: To test the need for electrode personalization, instead of a universal electrode for everyone, to induce neuromodulation effects on the bilateral primary motor cortex (M1) devoted to upper and lower limb representation., Methods: By an ad-hoc neuronavigation procedure, we shaped the personalized electrode and positioned it matching the projection on the scalp of the individual central sulcus by a 2 cm strip, with total area of 35 cm(2). The non-personalized electrode, i.e., equal for all subjects, was a 2 cm wide strip size-matched with the personalized electrode but shaped on a standard model fitting the curve passing through C3-CZ-C4 sites of the electroencephalographic (EEG) 10-20 International System. To test neuromodulation electrode-dependent efficacy, we induced a 20 Hz sinusoidal modulated current (transcranial alternating current stimulation, tACS) because it produces online effects. We simultaneously collected left and right hand and leg motor potentials (MEP) that were evoked by a rounded transcranial magnetic stimulation (TMS) coil. Through each electrode we delivered both real and sham stimulations., Results: While cortical excitability during tACS increased during both the non-personalized and the personalized electrodes for the leg, the hand representation excitability enhancement was induced selectively when using the personalized electrode. The results were consistent bilaterally., Conclusions: We documented that by using a personalized electrode it is possible to induce the neuromodulation of a predetermined extended cortical target, which did not occur with a non-personalized electrode. Our findings can help in building neuromodulation methods that might compensate for individual alterations across specific brain networks., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: Repetitive Transcranial Magnetic Stimulation (rTMS) has been recently employed as a therapeutic strategy for stroke, although its effects on cerebral hemodynamics has been poorly investigated. This study aims to examine the impact of high frequency rTMS on cerebral vasomotor reactivity (VMR)., Methods: Twenty-nine healthy subjects were randomly assigned to real (19) or sham 17-Hz rTMS, applied on primary motor cortex (M1) of the dominant hemisphere. All subjects underwent Transcranial Doppler of the middle cerebral arteries to evaluate mean flow velocity and VMR before (T(0)) and within 10 min (T(1)) following rTMS. Four subjects underwent further VMR evaluations at 2 (T(2)), 5 (T(3)) and 24 h (T(4)) after rTMS. As a control condition, 10 subjects underwent real (5) or sham rTMS on calcarine cortex. In addition, five acute stroke patients underwent five daily rTMS sessions on the affected hemisphere mimicking a therapeutic trial., Results: Following real rTMS on M1 (p=0.002) and calcarine cortex (p<0.001) VMR decreased with respect to T(0) in both hemispheres, while no change was observed after sham rTMS (p>0.6). VMR tended to remain lower than T(0) until T(3.) Cerebral VMR decreased independently of the stimulated side also in the patients' group., Conclusions: High frequency rTMS reduces cerebral VMR, possibly as a secondary effect on autonomic control of cerebral hemodynamics., Significance: The effect of rTMS on cerebral hemodynamics should be carefully considered before proceeding toward a therapeutic application in stroke patients.

One of the objectives of the HUman MicroNucleus (HUMN) project is to identify the methodological variables that have an important impact on micronucleus (MN) or micronucleated (MNed) cell frequencies measured in human lymphocytes using the cytokinesis-block micronucleus assay. In a previous study we had shown that the scoring criteria used were likely to be an important variable. To determine the extent of residual variation when laboratories scored cells from the same cultures using the same set of standard scoring criteria, an inter-laboratory slide-scoring exercise was performed among 34 laboratories from 21 countries with a total of 51 slide scorers involved. The results of this study show that even under these optimized conditions there is a great variation in the MN frequency or MNed cell frequency obtained by individual laboratories and scorers. All laboratories ranked correctly the MNed cell frequency in cells from cultures that were unirradiated, or exposed to 1 or 2Gy of gamma rays. The study also estimated that the intra-scorer median coefficient of variation for duplicate MNed cell frequency scores is 29% for unexposed cultures and 14 and 11% for cells exposed to 1 and 2Gy, respectively. These values can be used as a standard for quality or acceptability of data in future studies. Using a Poisson regression model it was estimated that radiation dose explained 67% of the variance, while staining method, cell sample, laboratory, and covariance explained 0.6, 0.3, 6.5, and 25.6% of the variance, respectively, leaving only 3.1% of the variance unexplained. As part of this exercise, nucleoplasmic bridges were also estimated by the laboratories; however, inexperience in the use of this biomarker of chromosome rearrangement was reflected in the much greater heterogeneity in the data and the unexplained variation estimated by the Poisson model. The results of these studies indicate clearly that even after standardizing culture and scoring conditions it will be necessary to calibrate scorers and laboratories if MN, MNed cell and nucleoplasmic bridge frequencies are to be reliably compared among laboratories and among populations.

As part of a regional International Atomic Energy Agency (IAEA) collaborative project within Latin America, five countries participated in an intercomparison in cytogenetic dosimetry. Coded slides for chromosomal aberrations and micronucleus analyses were prepared by the coordinator laboratory which organized the exercise and sent to the other participating laboratories. For estimates of dose, each laboratory scored the frequency of dicentrics in metaphases and the frequency of micronuclei in binucleated cells. The lymphocytes were irradiated with 60Co gamma-rays (0, 0.75, 1.5 and 3.0 Gy). Eleven of the 15 estimates of dose based on dicentrics and nine of the 12 based on micronuclei fell within +/- 30% of the true dose. When considering the uncertainties of the dose estimates, the true dose fell within the 95% confidence limits of the estimates on eight of the 15 occasions for dicentrics and four of the 12 for micronuclei.