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Biomedical subjects

S Suter

Publications and source records attributed to S Suter.

106 records · Page 6Linked to original sources
PubMed1981

Biofeedback regulation of temporal EEG alpha asymmetries.

Integrated EEG alpha was recorded from T3 and T4. Larger R alpha/L alpha ratios were defined as right asymmetry, relatively smaller ratios as left asymmetry. In different phases of the study, participants attempted to identify the presence of the EEG asymmetries and to produce the EEG asymmetries during auditory biofeedback, and were tested on hemisphere-specialized cognitive tasks while attempting to produce the EEG asymmetries. Experiential descriptions of the EEG asymmetries were obtained throughout using a set of bipolar scales. Some participants were able to identify the presence of the EEG asymmetries (p less than .05). As a group there was numerically small but significant (p less than .05) biofeedback control of the EEG asymmetries, but no improvement across sessions of training. There were marked individual differences in the ability to control the EEG asymmetries and in L alpha and R alpha during control. During baselines L alpha and R alpha were strongly positively correlated across time. Experiential descriptions were not consistent across participants. Effects of EEG asymmetries on performance of hemisphere-specialized tasks were demonstrated for one participant.

Adult↗
PubMed1981

Cleavage of C3 by neutral proteases from granulocytes in pleural empyema.

The possibility of direct inactivation of C3 by granular enzymes from polymorphonuclear leukocytes (PMNLs) in pleural empyema was examined. As a group, pleural empyema from 10 patients with purulent effusions and a positive bacteriologic culture cleaved significantly more 125I-labeled C3 bound to Sepharose (18.4% +/- 7.3%) than did 19 sterile pleural effusions (2.4% +/- 0.9%; P less than 0.001) and sonicates from bacterial strains commonly found in empyema (1.4% +/- 0.2%). Granular enzymes from 7 X 10(6) PMNLs cleaved 78.5% of 125I-labeled C3 bound to Sepharose. When proteolysis of 125I-labeled C3 after incubation with pleural empyema or PMNL granular enzymes was examined with polyacrylamide gel electrophoresis, breakdown products were similar. Granulocyte elastase-like activity was detected in four samples of pleural empyema. Granulocyte elastase inhibitors, as well as 10% human serum, effectively suppressed cleavage of C3 and elastase-like activity. In pleural empyemas, granula enzymes from PMNLs, especially elastase, apparently contribute to low complement-mediated opsonic activity by direct inactivation of C3.

Adult↗
PubMed1977

Independent biofeedback self-regulation of EEG alpha and skin resistance.

Skin resistance and EEG alpha were recorded concurrently during alpha biofeedback, in which the participant attempted to control alpha, and during skin resistance biofeedback, in which the participant attempted to control skin resistance. Alpha production changed significantly (p less than .001) during alpha biofeedback, indicating successful self-regulation of alpha, but did not change significantly during skin resistance biofeedback. Similarly, skin resistance changed significantly (p less than .001) during skin resistance biofeedback but did not change significantly during alpha biofeedback. The results show independent control of alpha and skin resistance, and may reflect independent self-regulation of cognitive and somatic tension-relaxation systems.

Adolescent↗
PubMedDate not supplied

Drawing and the cerebral hemispheres: bilateral EEG alpha.

Bilateral EEG alpha (alpha) was measured during several cognitive tasks in two experiments. EEG alpha was suppressed relative to baseline in both hemispheres during every drawing and writing task. In addition, there were task-related EEG alpha asymmetries. Differences in left-hemisphere, but not right-hemisphere EEG alpha activity, were responsible for EEG alpha asymmetry differences between writing and drawing tasks. There was no difference in bilateral EEG alpha during drawing an upright versus an inverted drawing stimulus; failing to support Edward's (1977, 1979) 'cognitive shift' approach to drawing instruction.

Adolescent↗
PubMedDate not supplied

Differentiation of VEP intermodulation and second harmonic components by dichoptic, monocular, and binocular stimulation.

Modulation by two temporal frequencies differentiates visual processing at the fundamentals (1Fs), second harmonics (2Fs), and second-order intermodulation components (IMCs), the latter created neurally as the sum or difference of the two modulation frequencies. Steady-state VEPs were recorded while stereo-normal adults viewed luminance or grating stimuli modulated by up to three temporal frequencies under dichoptic, monocular, or ordinary (binocular) viewing conditions arranged using liquid crystal light shutters. In Experiment 1, modulation of luminance by a single temporal frequency produced strong 1F and 2F VEP components, but modulation of gratings produced only 2Fs. Modulation by two temporal frequencies resulted in IMCs, often in the absence of evoked activity in the EEG at the 1Fs. IMCs were generally larger during pattern as compared to luminance modulation. Amplitudes of 1Fs and IMCs were smaller, but 2Fs were larger, during dichoptic as compared to ordinary viewing. Although the 2F to a single modulation presented to one eye was not reduced when a second frequency was added to the opposite eye, monocular IMCs were diminished when a frequency was added to the opposite eye. We conclude that 2Fs and IMCs are associated with different neural substrates. Results are consistent with a two pathway model with one pathway having a nonlinear filter prior to binocular combination, the other pathway having a nonlinearity following binocular linear summation. Implications of these data for binocular function are discussed.

Adult↗
PubMedDate not supplied

Complement activation in the adult respiratory distress syndrome following cardiopulmonary bypass.

We investigated complement fractions in patients after extracorporeal circulation for coronary bypass operations or cardiac valve replacement, and in two cases developing an adult respiratory distress syndrome (ARDS) after this type of intervention. The patients presenting an ARDS had significantly increased levels of C3d (p less than 0.001), the small molecular breakdown product of C3, associated with decreased levels of total classic haemolytic activity (p less than 0.05) and of the complement component C1q (p less than 0.001) when compared to a group of 10 patients who had uneventful evolution after bypass. However, all patients undergoing cardiopulmonary bypass had significantly increased levels of C3d (p less than 0.005 or less) associated with significant decrease of various complement components within 24 h after bypass, when compared to a control group of 5 patients investigated after aorto-iliac bypass graft surgery. We conclude that significant complement activation can persist in patients 24 h after bypass and--at higher levels--be a pathogenic and biological marker of ARDS after extracorporeal circulation.

Adult↗