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Whole Cortex (whole + cortex)
Selected AbstractsAn In Vitro Study of the Ultrasonic Axial Transmission Technique at the Radius: 1-MHz Velocity Measurements Are Sensitive to Both Mineralization and Intracortical Porosity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2004Emmanuel Bossy Abstract The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges). Using synchrotron radiation ,CT, we investigated, in vitro, the relationships between 1-MHz axial transmission SOS measurements at the radius and site-matched measurements of C.Th, POR, MIN, and vBMD. Introduction: The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges). Materials and Methods:Using synchrotron radiation ,CT, we investigated, in vitro, the relationships between 1-MHz axial transmission speed of sound (SOS) measurements at the radius and site-matched measurements of cortical thickness (C.Th), intracortical porosity (POR), tissue mineralization (MIN), and volumetric BMD (vBMD). SOS measurements were based on bidirectional axial transmission and were performed with a 1-MHz proprietary probe on 39 excised human radii. Results: The highest correlations between SOS values and bone parameters (R2SOS/POR = 0.28, p < 10,3; R2SOS/MIN = 0.38, p < 10,4; R2SOS/vBMD = 0.57, p < 10,3) were found for bone parameters assessed in a 1-mm-thick periosteal region of the cortex rather than throughout the whole cortex. The observed moderate correlation between SOS and C.Th values (R2SOS/C.Th = 0.20, p < 10,2) disappeared when controlled for other variables. The two best multilinear predictive models, including either BMD alone or the pair of dependent variables MIN and POR (all assessed in the periosteal cortex), were equally accurate in predicting SOS values (R2SOS/(POR,MIN) = 0.59, p < 10,5; R2SOS/vBMD = 0.57, p < 10,5). Conclusion: For the first time, the respective adjusted contributions of POR (,24 m/s%,1) and tissue mineralization (+3.5 m/s/mg/cm,3) to SOS values were assessed. These results suggest potential sensitivity of axial transmission SOS values to changes in cortical bone status under different pathological conditions or treatments affecting POR and/or tissue mineralization. [source] Topographic electroencephalogram in children during mask induction of anaesthesia with sevofluraneACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009E. SONKAJÄRVI Background: Epileptiform patterns, spikes, polyspikes and periodic epileptiform discharges (PED) have been reported in electroencephalograms (EEGs) during anaesthesia induction with sevoflurane in healthy adults and children. Published recordings have been performed with a limited number of channels, and therefore the topographic distributions of these patterns are not known. Methods: Twenty ASA I children aged 4,10 years undergoing routine operations were anaesthetized with 8% sevoflurane in 50%/50% oxygen and nitrous oxide using mask induction with controlled normoventilation. An EEG was recorded with a full 10,20 electrode system including orbitofrontal and ear electrodes, and a recording band of 0.016,70 Hz. Beat-to-beat heart rate (HR) was calculated off-line. Results: Nineteen out of 20 children developed multifocal spikes and polyspikes with a maximum over the frontal lobes. Four patients developed suppression, which was almost continuous and lasted several minutes, and thereafter a continuous EEG resumed, a few spikes were seen and then a nonepileptiform pattern. In three children a couple of PED waves were seen at the onset of a continuous EEG. HR increased maximally before the onset of spikes. No motor phenomena were seen. Conclusion: These recordings confirm the epileptogenic property of sevoflurane in mask induction. The spikes and polyspikes had frontal multifocal maxima and may be missed in recordings from frontopolar electrodes used by depth-of-anaesthesia monitors. PED and burst suppression were synchronous over the whole cortex. Epileptiform activity was indiscernible from epileptiform waveforms without anaesthesia, such as the patterns seen in status epilepticus. [source] Chronic Ethanol Administration Alters Immunoreactivity for GABAA Receptor Subunits in Rat Cortex in a Region-Specific MannerALCOHOLISM, Issue 8 2000A. Chistina Grobin Background: Chronic ethanol administration has a plethora of physiological effects. Among the most consistently observed findings is a change in the expression pattern of ,-aminobutyric acid type A (GABAA) receptor subunits in the rat brain cortex. These findings led to the hypothesis of "subunit substitution" to account for changes in receptor function without changes in receptor number. Methods: We used subunit (,1 and ,4) specific antibodies and a combination of immunohistochemistry and immunoblotting to examine subregions of cortex (prefrontal, cingulate, motor, parietal, and piriform) for their response to 2 weeks of forced ethanol administration. Results: Overall, cortical immunoreactivity for the ,1 subunit was decreased and for the ,4 subunit increased whether measured immunohistochemically or by immunoblotting. Piriform cortex exhibited a bidirectional change in GABAA receptor ,1 and ,4 immunoreactivity, similar to that previously observed in preparations of whole cortex. However, in parietal cortex, declines in ,1 immunoreactivity (55 ± 12% control value [CV] and 88.3 ± 4.3% CV; immunohistochemistry and immunoblotting, respectively) were not accompanied by concomitant increases in ,4 immunoreactivity (104 ± 8% CV and 116 ± 9.3% CV; immunohistochemistry and immunoblotting, respectively). Conversely, ,4 immunoreactivity increased in cingulate cortex (210 ± 30% CV and 134 ± 9.5% CV; immunohistochemistry and immunoblotting, respectively) without a decline in ,1 immunoreactivity (90 ± 4% CV and 91.3 ± 3.9% CV; immunohistochemistry and immunoblotting, respectively). Prefrontal and motor cortex exhibited GABAA receptor subunit peptide alterations, but these changes varied with the method of analysis. Conclusions: These findings demonstrate that ethanol dependence results in nonuniform changes in GABAA receptor subunit peptide levels across the rat brain cortex and suggest that mechanisms which subserve functional changes in receptor activity may vary in accordance with anatomic or cellular differences within the cortex. [source] Cortical folding difference between patients with early-onset and patients with intermediate-onset bipolar disorderBIPOLAR DISORDERS, Issue 4 2009Jani Penttilä Objectives:, Cerebral abnormalities have been detected in patients with bipolar disorder (BD). In comparison to BD with a later onset, early-onset BD has been found to have a poorer outcome. However, it is yet unknown whether neuroanatomical abnormalities differ between age-at-onset subgroups of the illness. We searched for cortical folding differences between early-onset (before 25 years) and intermediate-onset (between 25 and 45 years) BD patients. Methods:, Magnetic resonance images of 22 early-onset BD patients, 14 intermediate-onset BD patients, and 50 healthy participants were analyzed using a fully automated method to extract, label, and measure the sulcal area in the whole cortex. Cortical folding was assessed by computing global sulcal indices (the ratio between total sulcal area and total outer cortex area) for each hemisphere, and local sulcal indices for 12 predefined regions in both hemispheres. Results:, Intermediate-onset BD patients had a significantly reduced local sulcal index in the right dorsolateral prefrontal cortex in comparison to both early-onset BD patients and healthy subjects, and lower global sulcal indices in both hemispheres in comparison to healthy subjects (p < 0.05, Bonferroni corrected). Brain tissue volumes did not differ between groups. Conclusions:, This study provided the first evidence of a neuroanatomic difference between intermediate-onset and early-onset BD, which lends further support to the existence of different age-at-onset subgroups of BD. [source] | ||||||||||