Neuroprotection by both NMDA and non-NMDA receptor antagonists in in vitro ischemia.

We have investigated the relative contributions of oxygen and glucose deprivation to ischaemic neurodegeneration in organotypic hippocampal slice cultures. Cultures prepared from 10-day-old rats were maintained in vitro for 14 days and then deprived of either oxygen (hypoxia), glucose (hypoglycaemia), or both oxygen and glucose (ischaemia). Hypoxia alone induced degeneration selectively in CA1 pyramidal cells and this was greatly potentiated if glucose was removed from the medium. We have also characterised the effects of both pre- and post-treatment using glutamate receptor antagonists and the sodium channel blocker tetrodotoxin (TTX). Neuronal death following either hypoxia or ischaemia was prevented by pre-incubation with CNQX, MK-801 or tetrodotoxin. MK-801 or CNQX also prevented death induced by either hypoxia or ischaemia if added immediately post-insult, however, post-insult addition of TTX prevented hypoxic but not ischaemic damage. Organotypic hippocampal slice cultures are sensitive to both NMDA and non-NMDA glutamate receptor blockade and thus represent a useful in vitro system for the study of ischaemic neurodegeneration paralleling results reported using in vivo models of ischaemia.

Propidium iodide in vivo: an early marker of neuronal damage in rat hippocampus.

We have investigated the use of the fluorescent exclusion dye propidium iodide as a marker for acutely degenerating cells in vivo, and report here that combined injection of kainic acid and propidium iodide into the lateral cerebral ventricle results in labelling of CA3 pyramidal cells 1 and 6 h after injection. Alternate sections stained with thionin at these early times revealed little evidence of histologically detectable cell damage.

Brain-derived neurotrophic factor, but not neurotrophin-3, prevents ischaemia-induced neuronal cell death in organotypic rat hippocampal slice cultures.

We have investigated the neuroprotective actions of neurotrophins in a model of ischaemia using slice cultures. Ischaemia was induced in organotypic hippocampal cultures by simultaneous oxygen and glucose deprivation. Cell death was assessed 24 h later by propidium iodide fluorescence. Pre- but not post-ischaemic addition of brain-derived neurotrophic factor (BDNF) produced a concentration-dependent reduction in neuronal damage. Neurotrophin-3 was not neuroprotective. These data suggest that BDNF may form part of an endogenous neuroprotective mechanism.

Effects of mass media communications on health and safety habits: an overview of issues and evidence.

A review is presented of factors that have been investigated on their relevance in mass media communications that are specifically designed to alter health and safety related behaviours of the recipients. While alcohol consumption is a major concern in this paper, the evidence regarding the effective use of mass communications for the modification of other health and safety habits has also been incorporated. Specific topics include the choice of yardstick of effect, study methodology and the strength of conclusion this permits, as well as the dependency of the effect of mass communication upon its four constituent components: the source, the content of the message, the channel of communication, and the characteristics of the recipients. Reference is made to the effect of educational journalism related to the prevention of health problems and to efforts to increase the educational value of traffic accident reports in daily newspapers through the inclusion of information that is potentially helpful to accident avoidance.

Beyond the concept of risk homeostasis: suggestions for research and application towards the prevention of accidents and lifestyle-related disease.

On the assumption that risk homeostasis theory is a valid conceptualization of the process determining the aggregate loss due to traffic accidents per time unit of road-user exposure in a given jurisdiction, a general perspective for future research and application in the area of road accidents, accidents in other domains as well as in the area of lifestyle-dependent ill-health has been developed. It is proposed that further work be undertaken to phrase the theory in a mathematical format, to identify the processes mediating between input and output variables and to establish its potential for assisting in the progress towards a more general theory of human conduct in the face of uncertainty. Several implications for policies promoting safety and health have been worked out in the context of a preventative strategy called "expectationism" which aims to achieve these goals through interventions that enhance people's desire to be safe and healthy. Finally, various questions regarding the biological, behavioural and economic functionality of risk-taking have been raised and the need for clarification of the values of various safety goals and of the means to their end has been pointed out.

Field observation of advance warning/advisory signage for passive railway crossings with restricted lateral sightline visibility: an experimental investigation.

This study evaluated a newly proposed series of signs intended for passive crossings with restrictions to lateral sightline visibility. These signs provide advance warning of a crossing and the restriction to lateral visibility. In addition, the signs advise motorists to come to a complete stop before crossing. Motorist behaviour was examined before and after installation of these signs at a rural passive crossing. A second site was observed in parallel to control partially for any confounding effects. Results indicated that motorists reduced speed and searched approach quadrants longer at points in the approachway after installation of the signs. However, there was no reliable increase in the number of motorists coming to complete stop, engaging in search behaviours, or classified as safe. The results are discussed in terms of reasons for the lack of compliance with the sign advisory.

How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task?

The effects of alcohol ingestion were compared with those of prolonged wakefulness on a simulated driving task. Eighteen healthy, male subjects aged between 19 and 35 years drove for 30 min on a simulated driving task at blood alcohol concentrations of 0.00, 0.05 and 0.08%. Subjective sleepiness was assessed before and after the driving task. Driving performance was measured in terms of the mean and standard deviation (S.D.) of lane position (tracking); the mean and S.D. of speed deviation (the difference between the actual speed and the posted speed limit); and the number of off-road occurrences. Ratings of sleepiness increased with increasing blood alcohol concentration, and were higher following the driving task. With increasing blood alcohol concentration, tracking variability, speed variability, and off-road events increased, while speed deviation decreased, the result of subjects driving faster. The results were compared with a previous study examining simulated driving performance during one night of prolonged wakefulness [Arnedt, J.T., MacLean A.W., 1996. Effects of sleep loss on urban and motorway driving stimulation performance. Presented at the Drive Alert... Arrive Alive International Forum, Washington DC], using an approach adopted by Dawson and Reid [Dawson, D., Reid, K., 1997. Fatigue, alcohol and performance impairment. Nature 388, 23]. For mean tracking, tracking variability, and speed variability 18.5 and 21 h of wakefulness produced changes of the same magnitude as 0.05 and 0.08% blood alcohol concentration, respectively. Alcohol consumption produced changes in speed deviation and off-road occurrences of greater magnitude than the corresponding levels of prolonged wakefulness. While limited to situations in which there is no other traffic present, the findings suggest that impairments in simulated driving are evident even at relatively modest blood alcohol levels, and that wakefulness prolonged by as little as 3 h can produce decrements in the ability to maintain speed and road position as serious as those found at the legal limits of alcohol consumption.

Prevalence of Campylobacter jejuni and Salmonella during pig slaughtering.

It was found that 79% of healthy pigs, slaughtered in three different slaughterhouses in the Netherlands, were intestinal carriers of Campylobacter jejuni (mean number 4000 cfu per g), and 21% of the same pigs had Salmonella in the intestinal tract (mean number 10 cfu per g). Immediately after slaughter, Campylobacter was swabbed from 9% of the carcasses and Salmonella from 13%. It is concluded from these data that most of the contamination on carcasses does not originate directly from the intestinal tracts of the animals but rather from surfaces, equipment, and utensils in the slaughter hall. It was demonstrated that Salmonella could survive in the slaughter hall, whereas Campylobacter died off, probably due to its vulnerability to drying conditions and its inability to grow at temperatures below 30 degrees C. Campylobacter was not isolated from the carcasses after cooling. It had been shown earlier that this again was caused by dry conditions, brought about by the use of forced ventilation in the cooling rooms. In an additional investigation, Campylobacter was not isolated from 248 samples of minced pork (10 g each), whereas Salmonella was found in 13% of these samples.

Personal characteristics related to accident histories of Canadian pilots.

Over 8,800 returns of a questionnaire, distributed to Canadian pilots, were analyzed. Items were chiefly about life events, hobbies, humour, and characteristics which might bear on susceptibility to "pilot error" accidents. Sets of items were compiled which discriminated whether or not respondents had had an aircraft accident in the past 10 years. Around 70% of the respondents could be classified correctly according to the self-reported accident criterion. Somewhat over half the items were significant accident markers in at least one of four pilot-license categories examined. There was surprisingly little evidence of a "macho" syndrome associated with aircraft accidents; for example, participation in relatively risky hobbies was often negatively related to accident history. This report, like much past research, is entirely retrospective, so that some significant accident markers may only reflect accident aftereffects. Since the questionnaire was not anonymous, however, a follow-up study on the prediction of future accidents is feasible and is being considered.

[The microbiological status of dry sausage in East Netherlands]. / De microbiologische gesteldheid van droge worst in Oost-Nederland.

Dry fermented sausage (dfs) was the food most suspected in a number of outbreaks of salmonellosis and staphylococcal enterotoxaemia. Data on formulation and processing showed that over 75 per cent of 76 producers still manufactured dfs in a traditional manner: fermentation and drying at ambient temperature for ten days on an average, green room facilities not present. 'Modern' processes were characterised by fermentation in green rooms at elevated temperatures, thus limiting production time to six days on an average. However, precautions to prevent luxurious growth of S. aureus under these conditions were not adopted to any appreciable extent. Consequently, high S. aureus levels (greater than 10(4) cfu/g) were detected precisely in dfs from five manufacturers using rapid processes. Colony counts of Enterobacteriaceae were low in dfs (81 per cent of 151 samples less than 10(3) cfu/g), associated with relatively low pH and aw levels and a high concentration of salt. However, Salmonella was detected in 16 (11%) of the samples, both from 'traditional' and 'modern' producers. Improvement of manufacturing practices in the manufacture of dfs should be stimulated to guarantee wholesome and safe products.

[Developments in veterinary medicine and possible impact on veterinary practice and education]. / De ontwikkelingen in de diergeneeskunde en de mogelijke gevolgen voor de beroepsuitoefening en de opleiding.

What are the recent developments in the various fields of the veterinary profession and which adjustments in veterinary medicine are required for successful anticipation to these new conditions? Efforts are made to answer these questions from the point of view of each of the authors' professional disciplines. The authors all specialised in different fields of veterinary medicine. The present paper is a summary of each of the authors' editorial contributions on this subject as published in Fakulteitsnieuws (magazine of the Utrecht Faculty of Veterinary Medicine) in 1984 and 1985. Veterinary practice is found to be developing into two main directions: (i) veterinary medicine of pet animals which concentrates on the individual diseased animal and (ii) veterinary medicine of farm animals in which herd health control and preventive medicine are increasingly emphasized. In addition, industry has an increasing need for veterinarians having a specific veterinary pathobiological background. Optimum veterinary care requires veterinarians increasingly to concentrate on one of these (sub)disciplines. This implies that, in veterinary training, students should be afforded ample opportunity to achieve depth in the areas of personal interest. This is made possible by ensuring further differentiation in the veterinary curriculum and by setting up an intensive system of post-graduate education.