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In healthy subjects eye movements were analysed during body rotation, during trunk torsion either with the head passively held stationary in space or with the head voluntarily stabilized in space, and during voluntary head movements. Trapezoidal movements around the vertical axis were performed (+/- 40 degrees, plateau 10 s, duration of ramp 1 or 4 s). Moreover the influence of a tonic head deviation up to 40 degrees on optokinetic nystagmus and on vestibulo-ocular reflex during sinusoidal turning was examined. Eye movements were recorded by DC-electrooculography. Saccadic and slow components of eye movements and the shift of eye position during the plateau of the trapezoidal stimulus were analysed. For all modes of stimulation during the plateau no nystagmus occurred. At the end of the dynamic phase of the stimulus relatively frequent eye deviations--mostly in the direction of the head deviation--were observed, not only after turning the trunk with the head stabilized in space (cervical stimulation) but also after turning head and trunk together. The fact that such eye deviations are thus observed even in the absence of any tonic, especially cervical stimulus, supports the assumption that they cannot be attributed to a tonic stimulus but merely to an effect of the preceding phasic stimulus which outlasts them. Also amplitude and direction of eye shifts during the plateau do not depend on a tonic stimulus, but merely on the eye deviation reached at the end of the dynamic phase of stimulation. Optokinetic nystagmus and vestibulo-ocular reflex are not influenced by an additional tonic cervical stimulus.

Defence against oxidative damage by UV-generated free radicals in both guinea pig and human skin has been found to be mediated by the ubiquitous thioprotein, thioredoxin reductase. Human keratinocytes contain approximately 5% thioredoxin reductase in their total acidic protein fraction and also express membrane-associated enzyme activity in cells cultured in synthetic medium. The thioredoxin reductase/thioredoxin system has been shown to reduce superoxide anion radicals through hydrogen peroxide to water. However, both UVA and UVB radiation, below the minimal erythemal dose, generate a sufficiently high concentration of oxygen radicals to deactivate thioredoxin reductase considerably. In albino guinea pigs, enzyme deactivation was up to 70% for UVA and 66% for UVB (n = 10 animals/protocol). The application of sun blockers SPF4, SPF8 and SPF15 to albino guinea pig skin offered no significant protection for the deactivation of thioredoxin reductase by either UVA or UVB radiation. In the human population (n = 15), thioredoxin reductase was deactivated by 54% with UVA and 36% with UVB radiation, although the degree of enzyme inhibition depended on skin phototype (I-VI, Fitzpatrick Classification). SPF24 offered considerable protection for thioredoxin reductase against both UVA and UVB for skin types I and II. However, SPF24 yielded no significant protection with UVA for skin types III-VI, and enhanced the enzyme inhibition with UVB additively. These results indicate that UVB photo-oxidation of oxybenzone (the UVA filter in SPF24) may deactivate thioredoxin reductase in more pigmented members of the population by Michael addition of oxybenzone semiquinone to the thiolate active site of this enzyme.

Objective: This experimental study was initiated to determine whether transmyocardial laser revascularization (TMLR) after acute myocardial ischemia may improve clinical chemistry and diminish the amount of necrosis. In addition, the influence of TMLR on healthy myocardium was analyzed. Methods: The prolonged short-term effectiveness of TMLR was evaluated in 44 open-chest anesthetized pigs with (n = 21) or without (n = 23) the setting of acute myocardial ischemia (observation period 6 h): seven pigs served as controls (thoracotomy only). An additional seven pigs had left anterior descending artery (LAD) occlusion only (ischemia group). A subsequent 14 pigs were treated by TMLR (CO 2 ) prior to LAD occlusion: Seven pigs received one laser channel/cm 2 (group 1) and in seven pigs two channels/cm 2 in the LAD territory (group 2) were performed. In addition, 16 pigs underwent TMLR without ischemia: Eight pigs received one channel/cm 2 (group 3) and eight pigs two channels/cm 2 (group 4). Clinical chemistry, histo-chemical assesment and histology were performed. Results: TMLR limits the expansion of the myocardial infarction zone: laser group 2 indicated a significant smaller area of necrosis in the area at risk (ischemic group (31%) vs. laser group I (19%), P = ns; laser group 2 (7%) vs. ischemic group, P < 0.01; laser group 1 vs. 2, P < 0.01). The amount of the area of necrosis and ischemia of laser groups 3 and 4 compared with control did not differ significantly (P = ns). Preventive creation of microchannels before ischemia did not diminish ischemic parameters (P = ns). The myocardial water content-measurements (MWC) in the ischemia, laser 1 and 2 groups did not show any difference at the end of the experiment. except higher values of laser group 2 (P < 0.05). Laser groups 3 and 4 revealed significantly higher MWC values compared with control (P < 0.001). Conclusions: This prolonged acute study demonstrates that CO 2 -TMLR significantly reduces the amount of necrosis in the area at risk, but does not reduce cardiac ischemic markers. In healthy myocardium, TMLR significantly increases myocardial water content and ischemic parameters and induces small ischemic and very small necrotic areas surrounding open laser channels. Generally, the elevated cardiac enzymes and proteins are mainly attributed to the expected rise caused by vaporization of myocardial tissue in all laser groups.