Event-related potentials in a passive and active auditory condition: effects of diazepam and buspirone on slow wave positivity.

The effects of single, oral doses of diazepam (10 mg), buspirone (10 mg) and placebo on auditory event-related potentials were assessed in healthy volunteers. Subjects received two series of auditory stimuli: a series of identical stimuli presented in a neutral, passive condition and a series of identical standard tones (P = 0.8), but now intermixed with target tones (P = 0.2), in an active, oddball condition. The analysis focused on the average value of the potential in two different phases, from 250 till 574 ms post-stimulus (including P300) and from 576 till 900 ms post-stimulus (including late slow wave positivity). Event-related potentials for the standards of the oddball task were compared with the potentials of the same stimuli presented in the neutral condition. In addition, the classical comparison between the target and the standard in the oddball task was made. The first comparison was designed to isolate any effect of a change in the level of vigilance and attention due to involvement in the oddball task. This effect was evident as an increase in positivity that was smaller in the diazepam condition. The second comparison was designed to isolate the distinctive processing associated with task-relevant stimuli. This revealed that the P300 was reduced in the 250-574 ms window in the diazepam group. Both results suggest that cognitive processing of relevant stimuli is reduced by diazepam. Presumably, this is associated with the sedative effects of this drug. Consistent with this interpretation, subjects under the influence of diazepam made more omissions in the detection of targets in the oddball condition and had longer reaction times. In contrast to diazepam, the anxiolytic buspirone did not appear to have measurable effects on cognition.

Influence of diazepam and buspirone on human heart rate and the evoked cardiac response under varying cognitive load.

The influence of two anxiolytics on basal heart rate and on the evoked cardiac response elicited by auditory stimuli, was studied in humans. Diazepam (Valium) (7.5 mg) and buspirone (Buspar) (7.5 mg), which differ in their psycho-pharmacological profiles, were used. Prestimulus vigilance and cognitive load were manipulated by instructions allowing the subjects to ignore the stimuli, or requiring them to count the tones. Drug effects were obtained in subjective alertness, basal heart rate level, and the evoked cardiac response. Diazepam reduced subjective alertness, while buspirone did not. Diazepam apparently increased heart rate levels relative to placebo, in contrast to buspirone, which produced an apparent decrease in heart rate. These drug-induced prestimulus heart rate level effects were associated with differential decelerations immediately following stimulus onset and appear to reflect differences in prestimulus vigilance. Opposite effects of the drugs were also observed in the second, acceleratory, component of the of the evoked cardiac response, and these were found to be independent of the prestimulus drug effects. Compared with placebo, buspirone appeared to enhance the acceleratory component in the count condition, while diazepam led to an apparent reduction of this component. Enhancement of this acceleration after buspirone may reflect an increase in cognitive effort directed to the performance of task-relevant behaviour, while the reduction of this component after diazepam can be regarded as a cognitive-motivational neutralisation of signal value. The differential effects of the two anxiolytics support the separation of the evoked cardiac response into different components and may also have implications for the clinical use of the drugs.

[Glycosylation of hemoglobin and plasma proteins in petrochemical plant workers]. / Glikozylacja hemoglobiny i bialek osocza u pracowników zakladów petrochemicznych.

The concentration of glycosylated hemoglobin and (plasma) proteins has been measured in 111 workers of 6 MZRiP departments in Plock and in 54 healthy people. In all subjects the mean concentrations of glycosylated hemoglobin and glycosylated plasma proteins have been in so called "wide range of normal values". Significant shifts of glycosylated Hb concentrations have been found in two departments--those of ethylenederivatives and distillation. The concentration of glycosylated plasma proteins has been elevated only in workers of the Catalytic Processes Department.

[Multi-indicators in the biochemical and clinical evaluation of exposure of workers in the petrochemical industry. I. Preliminary epidemiologic screening studies]. / Wielowskaznikowa ocena biochemiczno-kliniczna narazenia pracowników przemyslu petrochemicznego. CZ. I. Wstepne badania epidemiologiczno-skriningowe.

Eleven non-routine biochemical and clinical indicators (selected of 26 preliminarily estimated) in Petrochemical Plant workers and in controls, localized in an increasing distance from the Plant (3-18-40 km), have been measured. Even in the 3 km distance, no effects of the Petrochemical Plant have been found. All the exposed groups exhibited changes in enzymes GGT and TA. We estimate these indicators as universal. The concentration of haptoglobin (Hp) changed in 3 groups, whereas sialic acid and arginase--in 2 exposed groups.

[Multi-indicator biochemical and clinical evaluation of occupational exposure of workers in the petrochemical industry. II. Results of the search for early clinico-biochemical signs of exposure to toxic substances present in the petrochemical industry. Analysis of the results of 5-year epidemiological studies]. / Wielowskaznikowa ocena biochemiczno-kliniczna narazenia pracownikówprzemyslu petrochemiczego. Cz. II. Wyniki poszukiwan wczesnych objawów kliniczno-biochemicznych narazenia na toksyczny wplyw substancji wystepujacych w przemysle petrochemicznym. Analiza wyników 5-letnich badan epidemiologicznych.

The activities of GGT (EC 2.3.2.1.) and glycine transaminidase (EC 2.6.2.1.) increased in all studied groups after at minimum four years of exposure to: acetobenzene, furfurol, ethylene--derivatives, polypropylene and butadiene. Besides these universal indicators the specific ones were found for a particular group of exposure: for acetobenzene--sialic acid, haptoglobine and IgA, for furfurol--sialic acid and haptoglobine, for ethylene--derivatives--haptoglobine, ceruloplasmine and the activity of arginase of the red blood cells, for polypropylene--IgA, for butadiene--proteolytic activity. These changes are treated as a manifestation of adaptive processes--the answer of the body to the environmental stimuli but not as the signs of early damage. The need of verification of the results by prospective studies is stressed.

Effects of the tranquillizer diazepam and the stimulant methylphenidate on alertness and memory.

Effects of alertness and memory of a single dose of diazepam (10 mg) and the central stimulant methylphenidate (20 mg) were studied in healthy volunteers. It was questioned whether opposite effects of diazepam and methylphenidate are not only observed with respect to alertness but also with respect to memory. It was also questioned whether the two drugs equally affect the first (primacy) and last (recency) items in both the immediate and delayed recall of newly learned words. The experiment was performed in a double-blind, placebo-controlled way. 12 subjects were exposed to a subjective alertness scale and a verbal memory test: a 15-word test. Subjective alertness was found to be decreased after diazepam and increased after methylphenidate. Anterograde amnesia was found after diazepam in the memory test. More specifically, the primacy but not the recency effect was reduced during the immediate recall and both were reduced in the delayed recall. methylphenidate had no effect on memory, however a ceiling effect might have obscured a putative drug effect. The results of a second experiment excluded this possibility. In all, the data demonstrate opposite effects of the two drugs on subjective alertness, suggesting opposite effects on vigilance. Opposite effects on memory were not established. This demonstrates that changes in alertness do not run in parallel with changes in memory. A scatter diagram, however, suggests a small effect of alertness on immediate recall. The effects of diazepam were also discussed in terms of the Atkinson and Shiffrin memory theory and it seems that diminished rehearsal processes are one of the key factors in explaining diazepam-induced amnesia.

Effects of diazepam and buspirone on reaction time of saccadic eye movements.

Effects of the anxiolytic drugs diazepam and buspirone were studied on the reaction time of saccadic eye movements. The study was performed with 8 healthy volunteers in a double-blind, placebo-controlled way. The purpose was to investigate the putative drug effects on the first step of an attention shifting task: the disengagement of attention. Saccadic reaction time was measured in two conditions: the 'gap' and the 'overlap' condition. In the first condition a delay is present between the offset of a fixation spot and the onset of a target, while in the second condition the offset of the spot is overlapped by the onset of the target. Clear differences in saccadic reaction time in the expected direction were found between the two conditions, with longer reaction times of saccadic eye movements in the overlap condition. The nonsedative anxiolytic buspirone in a dose of 5 mg had no significant effects on saccadic reaction times, while clear effects of diazepam in a dose of 5 mg were established. Diazepam slowed down saccadic reaction times, reduced the number of fast saccades and facilitated the number of slow saccades. However, the effects induced by this drug were identical for the two conditions. The latter result implies that the disengagement of attention is not selectively disrupted by diazepam. Perhaps, the action of diazepam is expressed in other attention factors, such as in shifting attention or in the reengagement of attention. A slowing down of these processes by the vigilance-lowering properties of diazepam might be the cause of the prolonged latencies. The increased latencies of saccadic eye movements induced by a low dose of diazepam may have practical implications.