Bijdragen tot de kennis der Nederlandse Desmidiaceeënflora, 2. Desmidiaceeën uit het Mosterdveen

The Desmidflora of the Mosterdveen (a complex of small fen soaks in the Netherlands province of Gelderland) provides a good example of a microphyte cenose characteristic of an oligotrophic type of water (as described by BEIJERINCK, 1926), which has in the meantime become very rare. The most typical indicator species found in the Mosterdveen are Cosmarium ralfsii Bréb., Micrasterias jenneri Ralfs, Euastrum crassum (Bréb.) Kütz., and Xanthidium armatum (Bréb.) Rabenh. Some species whose occurrence and distribution in the Netherlands is not so well known, partly owing to their problematic taxonomy, are discussed separately

Lead exposure during demolition of a steel structure coated with lead-based paints. II. Reversible changes in the conduction velocity of the motor nerves in transiently exposed workers.

In a group of workers exposed to high levels of lead during five months nerve conduction velocity parameters were evaluated at the termination of exposure, and also three and fifteen months later. At the termination of exposure the mean blood lead level was 4.0 ??mol/l, and motor conduction velocities in the median and the ulnar nerves were slower and the distal latencies in the median nerve were longer compared to the values measured 15 months later. Sensory conduction velocities, measured distally in the same nerves, were not depressed compared to the values measured three or fifteen months later. It was tentatively concluded that the effect of lead on the conduction velocity of the motor nerves has an initial reversible phase, dependent on the duration of exposure. Chemicals/CAS: lead, 7439-92-1; Air Pollutants, Occupational; Lead, 7439-92-1 This work is licensed under a Creative Commons Attribution 4.0 International License

Changes in regional brain GFAP levels and behavioral functioning following subchronic lead acetate exposure in adult rats

Adult male WAG/Rij/MBL rats were dosed with lead acetate at 0, 4.0, 8.0 or 12.5 mg/kg, 5 days per week for 4 weeks. Animals were assessed prior to exposure, at the end of the 4-week exposure period and after a 2-week recovery period using a functional observational battery (FOB) and motor activity assessment. Rats were sacrificed two weeks after the last test session and glial fibrillary acidic protein (GFAP) concentrations were measured in eight selected brain regions. A dose-dependent decrease in motor activity was observed immediately following the end of the exposure period with no differences observed 2 weeks after cessation of exposure. Alterations in gait, decreased fore-and hindlimb grip strength, and decreased arousal were also found. Behavioral changes were accompanied by reduced weight gain and decreased body temperature during the course of exposure. GFAP concentrations were elevated in the frontal cortex, occipital cortex, striatum and hippocampus but not in thalamus, cerebellum or brain stem. These results indicate that lead causes functional effects in the adult rat which can be detected by neurobehavioral methods. Furthermore, region-specific alterations in brain GFAP concentrations provided evidence of specificity of lead neurotoxicity in the adult brain

Neurobehavioral effects of cyclohexane in rat and human

The neurobehavioral effects of inhaled cyclohexane in rats and humans are investigated to define relationships between internal doses and acute central nervous system effects. Rats are exposed for 3 consecutive days at target concentrations of 0, 1.4, 8, and 28 g/m3, 8 h/d. Measurements include standardized observational measures, spontaneous motor activity assessments, and learned visual discrimination performance. Cyclohexane concentrations in blood and brain are measured to assess internal exposure. Human volunteers are exposed for 4 hours to 86 or 860 mg/m3 in 2 test sessions. Neurobehavioral effects are measured using a computerized neurobehavioral test battery. In rats, there are slight reductions in psychomotor speed in the high-exposure group but minimal central nervous system effects. In humans, there are no significant treatment-related effects at the levels tested. © The Author(s) 2009

Model studies for evaluating the acute neurobehavioral effects of complex hydrocarbon solvents. I. Validation of methods with ethanol

As a preliminary step to evaluating the acute neurobehavioral effects of hydrocarbon solvents and to establish a working model for extrapolating animal test data to humans, joint neurobehavioral/toxicokinetic studies were conducted which involved administering ethanol to rats and volunteers. The specific objectives of the present studies were to evaluate the acute central nervous system (CNS) effects of ethanol in rats and humans and to assess relationships between internal levels of exposure and behavioral effects. A more general objective was to validate a battery of neurobehavioral tests that could be used to carry out comparative studies in both species. Accordingly, a range of tests including standardized observational measures, spontaneous motor activity assessments and learned visual discrimination performance was utilized in rat studies to evaluate acute CNS effects. Groups of rats were given ethanol at levels of approximately 0.5, 1.0 or 2.0 g/kg, with blood level measurements to verify internal doses. In a volunteer study, 12 healthy male subjects were given 0.65 g/kg ethanol, a level approximating the limit for motor vehicle operation in The Netherlands, and neurobehavioral effects were measured prior to and 1 and 3 h after ethanol administration, with a computerized neurobehavioral test battery. Blood and air measurements were made to quantify internal doses. Results of the behavioral tests in rats provided evidence of ethanol-induced changes in neuromuscular, sensori-motor, and activity domains. There were also significant changes in visual discrimination, particularly in the areas of general measures of responding and psychomotor speed. In humans there were small but statistically significant effects on learning and memory, psychomotor skills and attention. However, the effects were subtle and not all parameters within given domains were affected. These studies demonstrated a qualitative similarity in response between rats and humans. © 2006 Elsevier Inc. All rights reserved