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Objective: To investigate the effects of maintaining a constant preload and of maintaining a constant degree of thumb abduction on the isometric twitch force during mechanomyography of the thumb, we monitored neuromuscular function in patients anaesthetized without the use of a neuromuscular blocking agent. In addition, we studied the relationship between the degree of thumb abduction, twitch force and preload., Methods: Fourteen patients were divided randomly into two groups, determining the sequence of the experiments in respect of correcting the preload and maintaining a constant degree of abduction after allowing the twitch forces to stabilize. Both experiments lasted 15 minutes. In both groups the relationship between the degree of thumb abduction, twitch force and preload was studied., Results: We found a progressive increase in twitch force both with (6.6%; CI: 3.7-9.3%; p < 0.001) and without (1.9%; CI: 0.4-3.5%; p = 0.020) continuous correction of the thumb preload. A significant greater increase in twitch force was seen when the preload had been corrected than when it was not (4.7%; CI: 0.8-8.7%; p = 0.023). In addition, both twitch force and preload appeared to depend on the degree of thumb abduction both before and at the time of measurement., Conclusions: Changes in length of the contracting muscle fibres and creep phenomena in the connective tissue of the muscles, both leading to changes in the sarcomere length of the muscle fibres, may explain the observations in this study. In general, a stabilized preload at a constant degree of abduction seems to be required in order to obtain a stable twitch force.

One of the methadone programmes of the Amsterdam Municipal Health Service is the 'methadone by bus' project. Two mobile clinics cruise the city, stopping at six different locations daily. The liquid methadone is consumed on the spot and clean needles and condoms are available. This project is based on the principles of 'harm-reduction', i.e. if it is not (yet) possible to 'cure' a hard drug user, one should at least try to minimize the harm they cause to themselves and their environment. As soon as a client refrains from the use of illegal drugs, the client can 'graduate' to other methadone programmes with a higher threshold. To prevent double prescription, all Amsterdam methadone programmes participate in the central methadone registration. The Amsterdam Municipal Health Service has contact with over 50% of the drug users. The estimated number of hard drug users has remained stable over the last 5 years, whilst the average age of drug users has increased to 32 years. In the future, increasing the average dosage and the provision of injectable drug users will be discussed to assess their role in further harm reduction.

In summary, it can be stated that Amsterdam has a wide variety of helping modalities. Approximately 70 percent of the city's 7,000 drug addicts are in contact with this helping system. In The Netherlands, no evidence could be found to support the fear that low-threshold methadone programs keep addicts away from drug-free treatment. Figure 1 shows that the number of addicts entering drug-free treatment doubled in the period 1981-85 (most popular has been the drug-free aftercare). This is even more striking since the estimated number of addicts did not increase in that same period. So, instead of keeping addicts away from treatment, low-threshold programs and outreach activities may have been effective tools in motivating addicts to enter drug-free treatment. Figure 2 shows the rise of the mean age of drug addicts, while figure 3 indicates that the percentage of addicts under 22 years decreases (14.4 percent in 1981 and 5.1 percent in 1986). Since the total number of addicts is quite stable, this may suggest that heroin is becoming less attractive to young people.