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The effect of d-amphetamine on the learning capacity of male Wistar rats was investigated in multiple T-mazes in two experiments of increasing or decreasing degree of difficulty. Running speed, distance covered and the number of errors were scored to indicate proficiency and success of learning. These parameters, as well as the distribution of errors (goal-directed orientation), correction of errors (situational orientation) and latency at the decision points (discrimination time) were considered to represent cognitive components. The results demonstrated an experiment effect in that the rats showed more difficulty in learning, as exhibited by a slower running speed and more errors, in the maze with successively increasing demands than in the one with decreasing demands. Oral self-administered d-amphetamine in a dosage of 3-4 mg/kg/day or 7-8 mg/kg/day significantly increased the running speed in a dose-dependent manner. By contrast, success of learning and goal-directed orientation decreased. Situational orientation was, however, dose-dependently improved, at least in the experiment with the increasing demand.

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Iotrolan, the radiologically effective ingredient of the contrast medium Isovist, has so little osmotic activity that only solutions of about 300 mg I/ml are isotonic to cerebrospinal fluid (CSF). The osmolality of the contrast medium at lower iodine concentrations has to be increased through additives. Theoretically, iotrolan 300 diluted with CSF is the most physiologic. Therefore, the commercial preparation iotrolan 190 (adaptation of the osmolality through the addition of saline and sodium bicarbonate) was tested in a randomized, single-blind study against a diluted contrast medium solution, iotrolan 190 (produced from iotrolan 300). The dilution was performed with the patient's own CSF. The test was carried out in lumbar myelography in two groups of 50 patients each. There were neither statistical nor tendency differences between the two preparations in either the opacification or the tolerance. Therefore, there is no suggestion that a contrast medium solution prepared with the patient's own CSF is better tolerated.

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This prospective multicenter study analyzes the image quality and incidence of undesirable side effects in 2543 film and 1133 intravenous digital subtraction angiographic (DSA) examinations with iopromide. It can be shown that the frequency of undesired side effects in both methods is twice as high in patients at risk as in patients without special risk factors. The most frequent side effects are gastrointestinal and, in cerebral angiography, of a central nervous system nature. The image quality for 99% of the film angiographies was good or better. It could be demonstrated for the DSA that a higher iodine concentration of 370 mg I/ml tends to result in a reduction of the image quality with an increased rate of side effects.

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The liver and kidney tolerance of iopromide 370 in comparison to that of sodium meglumine diatrizoate 370 or iopamidol 370 in doses of 2 ml/kg body weight was examined in two controlled double-blind studies with intravenous digital subtraction angiography on the basis of enzyme assays in serum and urine. In patients with normal kidney function no changes were observed in the levels of the liver enzymes GPT, GOT, and gamma glutamyl transpeptidase (GGT) serum up to 72 hours after injection of iopromide or sodium meglumine diatrizoate. Among the kidney-specific enzymes, the excretion of GGT in urine increased after injection of iopromide and iopamidol. The maximum increase of GGT excretion was, however, statistically significantly lower in the group treated with iopromide than in the iopamidol group. Within 72 hours, the activities had been returned to the initial values in both groups.

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In new of previous contradictory results, the possible interaction between the loop diuretic furosemide and theophylline was re-evaluated in 12 healthy volunteers with a steady-state plasma theophylline level. Two doses of furosemide 20 mg at a 4 h interval did not influence the steady-state plasma concentration of theophylline despite causing a moderate diuresis. Urinary recovery of theophylline and its metabolites amounted to 106 +/- 21% of the dose without furosemide and 96 +/- 19% of the dose with furosemide, demonstrating that there was no influence on the enteral absorption of theophylline of the furosemide treatment. After the first dose of furosemide the fractional renal clearance (CLR1) of theophylline (fractional = hourly sampling period) changed in parallel with the urinary flow rate, without a significant difference between treatment with and without furosemide. After the second dose of furosemide, CLR1 was increased in the first hour and then it declined to levels far lower than the control value. This unexpected result could explain the unchanged plasma concentration of theophylline during furosemide treatment.

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The activity of different-aged monkeys belonging to three species of Cercopithecidae was quantitatively analyzed in a 1 1/2-year study. The species, silvered-leaf monkey (Presbytis cristatus Esch.), lion-tailed monkey (Macaca silenus L.) and moor macaque (Macaca maura Cuv.) were observed in the Zoological Garden, Berlin (West). The data of a combined cross-sectional analysis across all three species indicate that the course of age-related changes in the frequency of movement can be depicted as graduated and differentiated. These results are discussed in terms of a reverse development pattern in old age compared to that of early youth.

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The drinking behavior of naive rats changes predictably in a free choice experiment involving water vs. 0.02%, 0.01% and 0.003% (+)-amphetamine solutions: The higher the concentration of the amphetamine solution, the sooner a number of rats quit drinking it, and the less is ingested by those still drinking it. Physically dependent rats having undergone three withdrawals immediately reject (+)-amphetamine solution in a free choice test with water available. The avoidance of withdrawal symptoms does not motivate further self-administration. Therefore, (+)-amphetamine self-administered in drinking water is neither a reinforcer for naive nor for physically dependent rats in sustaining drug taking behavior. In acute and chronic experiments, the transition from increased motor activity to stereotypical behavior could be demonstrated and evidence was produced that tolerance develops to the (+)-amphetamine-induced increase in motor activity.

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Investigations were performed to determine whether the pharmacodynamic effect of barbital, the development of tolerance to or the physical dependence on the hypnotic are responsible for drug-taking behavior. Three groups of male rats, untreated, tolerant to and physically-dependent on barbital, were given free choice between 0.5% barbital solution and tap water. Drug-taking behavior was estimated according to specified criteria. Initially naive rats rejected an unsweetened barbital solution. Tolerant rats also refused the hypnotic, even after they had experienced abstinence symptoms only once. However, tolerant rats that repeatedly underwent withdrawal after an intake of more than 400 mg/kg/day of barbital did show drug taking behavior. Therefore, several experiences with pronounced abstinence symptoms seem to be necessary for initiating and sustaining barbital drug taking behavior in rats.

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