Neural activity associated with executive functions in adolescents with attention-deficit/hyperactivity disorder (ADHD).

This study used event-related potentials (ERPs) and flanker-task performance to compare executive functions in adolescents with ADHD, their siblings and independent healthy controls. The aim was to investigate the processing of distracting stimuli, control over inappropriate responses, and the detection of errors in the presence of incompatible and No-go stimuli (arrow-heads and a circle, respectively). Performance showed no major differences between the groups, although No-go errors were numerically increased for the patients.

Occupational styrene exposure, colour vision and contrast sensitivity: a cohort study with repeated measurements.

Objective: Associations between occupational styrene exposures and impairment of visual functions were investigated with a view to answering three questions: (1) are the published findings for colour vision deficiencies and impaired contrast sensitivity to reproduce in a new study approach, (2) if such effects exist, are they related to current or chronic exposures and (3) if effects exist, are there reductions in the effects during an exposure-free period?

Methods: Workers from a boat building plant were examined in groups of current low [n = 97, mean mandelic acid (MA) + phenylglyoxylic acid (PGA) = 51 mg/g creatinine], medium (n = 115, mean = 229 mg/g creatinine) and high (n = 30, mean = 977 mg/g creatinine) level exposure to styrene. Job tenure was about 6 years. In addition, subgroups chronically exposed to low-short (n = 34, lifetime weighted mean 200 mg/g creatinine for 6 years) and high-long (n = 17, mean = 660 mg/g creatinine, 15 years) styrene levels were analysed.

Occupational styrene exposure and neurobehavioural functions: a cohort study with repeated measurements.

Objective: Associations between occupational styrene exposure and cognitive as well as psychomotor functions were investigated with a view to answering three questions: (1) are the published results for neurobehavioural impairment reproducible, (2) if such effects exist, are they related to current or to chronic exposure and (3) if effects exist, are there reductions in the effects during an exposure-free period.

Methods: Workers from a boat-building plant, some of whom were laminators, were investigated in groups of low (n = 83, mean mandelic acid MA + phenylglyoxylic acid PGA = 53 mg/g creatinine), medium (n = 101, 230 mg/g creat.) and high (n = 29, 928 mg/g creat.

Effects of ageing on cognitive task preparation as reflected by event-related potentials.

Objective: The anticipation of complex cognitive tasks involves effortful preparation being reflected in the contingent negative variation (CNV) of the event-related potential. In the literature there are contradictory results concerning the effect of age on this potential. We wanted to investigate effects of age, time-on-task, and task difficulty on the CNV.

Effects of aging on slowing of motor-response generation.

The aim of the present study was to analyze different stages of central processing mechanisms during a choice reaction task and to evaluate their contribution to aging-related response slowing. Event-related potentials (ERPs) were recorded from two groups of subjects, young (mean 22 years) and older adults (mean 58 years), who performed a four-alternative choice-reaction task. The results showed the expected reaction time slowing in the older subjects.

Risk potentials for humans of original and remediated PAH-contaminated soils: application of biomarkers of effect.

Contaminated soils represent a potential health risk for the human population. Risk assessment for humans requires specific methods, which must reflect the peculiarities of human behaviour, physiology and biochemistry with respect to contaminant uptake and processing. Biomarkers of effect or exposure have become an appropriate tool.

Parallel systems of error processing in the brain.

Major neurophysiological principles of performance monitoring are not precisely known. It is a current debate in cognitive neuroscience if an error-detection neural system is involved in behavioral control and adaptation. Such a system should generate error-specific signals, but their existence is questioned by observations that correct and incorrect reactions may elicit similar neuroelectric potentials.

[Cytochemical parameters of myeloperoxidase activity and catecholamine level in blood of postpartum women living in areas near the Semipalatinsk nuclear test site].

The activity of neitrophil myeloperoxidase and content of blood etyrhrocyte cathecholamines in the blood of women in early postpartum period in dependence on distance of their living area from Semipalatinsk nuclear testing were studied. It was found that women who live closer to Semipalatinsk were characterised by significantly lower neitrophil myeloperoxidase activity and content of cathecholamines in erythrocytes than in control.

Integration of mechanistic data in the toxicological evaluation of endocrine modulators.

Controversy has arisen concerning the likelihood of adverse health effects due to exposure to hormonally active agents or endocrine modulators such as environmental estrogens. With the aim to improve the basis for their toxicological evaluation, several chemicals of anthropogenic (bisphenol A, octylphenol, o,p'-DDT) and of natural origin (daidzein, genistein) were investigated with regard to their mode of hormonal action and potency as well as toxicokinetics. Experimental toxicodynamic and toxicokinetic data illustrate important points in a comparative assessment of environmental estrogens.

Psychomotor performance and subjective symptoms at low level toluene exposure.

Objectives: Possible effects of long term occupational exposure to toluene below the level of 100 ppm on psychomotor performance and subjective symptoms were investigated in a cross sectional approach.

Methods: From German rotogravure printing plants 278 male workers, mean age 39.8 years, mean duration of employment 14.

The enhanced bladder cancer susceptibility of NAT2 slow acetylators towards aromatic amines: a review considering ethnic differences.

Human bladder cancer may be caused by exposure to aromatic amines. The polymorphic enzyme N-acetyltransferase 2 (NAT2) is involved in the metabolism of these compounds. Two classical studies on chemical workers in Europe, exposed in the past to aromatic amines like benzidine, unambiguously showed that the slow acetylator status is a genetic risk factor for arylamine-induced bladder cancer.

Psychological effects upon exposure to polyhalogenated dibenzodioxins and dibenzofurans.

Thirty workers who had been exposed to combustion products for several years due to testing of flame retarding qualities of building materials and 30 controls from the same facility were investigated. Concentrations found in samples taken from different places of the facility were up to 14,660 microg/kg for polybrominated dibenzofurans and up to 67.1 microg/kg for polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs).

Association of biochemical and subjective indicators of drinking habits with performance on different neurobehavioral tasks.

The present paper outlines the association of biochemical and subjective indicators of alcohol consumption. Due to its relevance as a potential confounding variable in occupational neurotoxicology, both sources of information about drinking habits were related to neurobehavioral test performance. A sample of 308 rotogravure printers and control subjects from a cross-sectional longitudinal study in various German printing plants was studied.

Neurobehavioral effects of solvents and circadian rhythms.

Two studies on the combined neurobehavioral effects of shiftwork and solvent exposure were performed: two-shift work/mixed solvent exposure and three-shift work/single solvent exposure (acetone). Repeated measurements of exposure, body temperature, well-being, complaints, and performance were taken during each shift and during several shift cycles. The air concentrations of the solvent mixture were clearly below and of acetone were near the occupational exposure limit values.

Physiological changes during computer tasks: responses to mental load or to motor demands?

Cardiac and electrodermal measures are regarded as indicators of user strain during computer work, not taking the possible influence of finger and hand movements on these measures into account. For the evaluation of such effects, motor demands and mental load were both varied as independent factors in two experiments. As a motor task, subjects had to produce compensatory keystrokes at different speed levels to keep a moving mark within a target area on the computer screen.

A note on distribution of human plasma levels of ascorbic and dehydroascorbic acid.

Ascorbic acid concentrations in 102 human plasma samples ranged from 1 to 15 micrograms ml-1 with a mean concentration at about 8 micrograms ml-1, corresponding to the results of other authors. Dehydroascorbic acid was found only in traces, independent of ascorbic acid concentrations. The ascorbic acid concentrations in plasma of four persons, examined twice with a four-years interim period revealed no obvious differences over time.