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A Schnee

Publications and source records attributed to A Schnee.

2 recordsLinked to original sources

Rats are able to navigate in virtual environments.

Virtual reality (VR) systems are useful tools that enable users to alter environmental settings and the location of landmarks in an accurate and fast way. Primates have been shown to be able to navigate in virtual environments. For rodents, however, all previous attempts to develop VR systems in which rats behave in the same way as in corresponding 3-D environments have failed. The question arises as to whether, in principle, rodents can be trained to navigate in a properly designed virtual environment (VE), or whether this peculiarity is limited to primates and humans. We built a virtual reality set-up that takes the wide-angle visual system of rats into account. We show for the first time that rats learn spatial tasks in this VE quite readily. This set-up opens up new opportunities for investigations of information processing in navigation (e.g. the importance of optic flow or vestibular input).

Animals↗

Increased antitumour activity of mesyl-I-aldophosphamide-perhydrothiazine, in vivo but not in vitro, compared to I-aldophosphamide-perhydrothiazine.

When equitoxic dosages of ifosfamide and I-aldophosphamide-perhydrothiazine (IAP) were tested for antitumour activity in the P388 mouse leukaemia model, 80% long-term survival (for more than 100 days) was achieved with IAP whereas, in the ifosfamide group, all mice died from tumour growth within 60 days. Even better antitumour activity, compared with ifosfamide, was observed with an IAP derivative (SUM-IAP) in which one 2-chloroethyl group of the alkylating function is substituted by a mesylethyl group. Evaluation of tumour growth curves following treatment with IAP and SUM-IAP revealed the antitumour activity of SUM-IAP to be 10(4)-10(5) times higher than that of IAP. In contrast to the results of these in vivo experiments, IAP was more cytotoxic against P388 mouse leukaemia cells in vitro than was SUM-IAP. The inverse correlation of in vivo antitumour activity and in vitro cytotoxicity indicates that the factors leading to the increase of antitumour activity following chemical modification of IAP differ from those involved in cytotoxicity on the cellular level.

Animals↗