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Biomedical subjects

B Nickel

Publications and source records attributed to B Nickel.

At least 73 records · Page 4Linked to original sources
PubMed1987

Putative site(s) and mechanism(s) of action of flupirtine, a novel analgesic compound.

The mechanisms of the antinociceptive action of flupirtine, a novel non-opioid analgesic, were investigated in animals. It was found that this effect could be abolished by pre-treatment with reserpine. Furthermore, it could be dose-dependently antagonized by yohimbine and changes in the EEG of the rat observed after administration of flupirtine were closely related to those obtained after giving clonidine. On these pharmacological results, it is likely that the antinociceptive activity of flupirtine is due to activation of descending noradrenergic pathways.

Aminopyridines↗
PubMed1986

Fenetylline: new results on pharmacology, metabolism and kinetics.

In the fenetylline molecule, theophylline is covalently linked with amphetamine via an alkyl chain. The inclusion of amphetamine and results from early metabolic studies have led to speculation that fenetylline may be merely a prodrug for amphetamine and/or theophylline. Although previous studies are not consistent with this hypothesis, additional studies were conducted to comparatively evaluate the profiles of activity exhibited by fenetylline and its two postulated primary metabolites, (+/-)-amphetamine and theophylline. Investigations were also initiated using newly developed high pressure liquid chromatography (HPLC) techniques to further characterize the metabolic pattern that fenetylline undergoes and to examine the relationship between plasma pharmacokinetics and the pharmacodynamic actions of the drug. Fenetylline inhibits activity associated with amphetamine in certain test systems, an effect similar to that previously observed with fenfluramine. Only small amounts of the amphetamine theoretically available in the fenetylline molecule are released. Pharmacodynamic activity associated with fenetylline administration is more closely tied to plasma levels of the parent compound than to any (+/-)-amphetamine produced.

Amphetamines↗
PubMed1986

'Fingerprints' of central stimulatory drug effects by means of quantitative radioelectroencephalography in the rat (tele-stereo-EEG).

The new electrophysiological model earlier described as stereo-EEG is extended now to allow recording from the freely moving rat by means of a telemetric device. Chronic implantation of 4 electrodes into the brain allows simultaneous transmission of field potentials from frontal cortex, hippocampus, striatum and reticular formation. Frequency analysis of these potentials results in a drug-specific 'fingerprint' which cannot only be used to compare different chemicals with each other but also to detect onset and time dependence of drug actions. Application of the model to the question if fenetylline has its own intrinsic mode of action or merely develops its stimulatory effect after metabolic separation into its molecular moieties amphetamine and theophylline (prodrug hypothesis) revealed that fenetylline indeed displays its own stimulatory effect to the same extent and at a similar time course as amphetamine and theophylline. The 'fingerprint' as obtained by the analysis of the action of fenetylline in the rat resembles closely that obtained after the application of theophylline with respect to decreased alpha activity, but resembles amphetamine with respect to beta 1 activity. Thus the applied method allows studying structure function relationships as the action of fenetylline seems to reflect both its molecular moieties.

Amphetamine↗
PubMed1986

Radioelectroencephalography (Tele-Stereo-EEG) in the rat as a pharmacological model to differentiate the central action of flupirtine from that of opiates, diazepam and phenobarbital.

Chronic implantation of 4 bipolar concentric electrodes into frontal cortex, thalamus, striatum and reticular formation allowed repeated recordings of field potentials from freely moving rats. After radiotransmission the signals were quantitatively evaluated by spectral power analysis. The power in particular frequency bands changed in the presence of drugs in a characteristic manner and allowed us to describe the central action of analgesics in comparison with diazepam and phenobarbital. Analysis of the data showed that the action of diazepam was mainly confined to alpha 1 and beta 2 frequencies whereas tramadol acted predominantly on the theta and alpha range. Buprenorphine and morphine most consistently influenced the alpha 2 frequencies. Whereas buprenorphine and tramadol (2 opiate drugs) showed a striking similarity to the action of morphine in corresponding brain areas the minor tranquilizer diazepam and the anticonvulsive phenobarbital could clearly be separated from them. Flupirtine, a new analgesic not suspected of an opiate-like action profile, did not resemble any of them and thus could be confirmed to have a different mode of action.

Aminopyridines↗
PubMed1985

[Mechanism of action of the analgesic flupirtine].

To answer the questions of mode and site of action partly supplementary, partly new investigations with flupirtine (Katadolon) were carried out which are described below. The investigation for opiate receptor affinity of flupirtine in rat brain homogenate did not show any reduction in 3He-etorphine binding up to the highest concentration of flupirtine of 10(-5) mol/1. This result suggests that flupirtine either has a very low opiate receptor affinity or lacks it fully. Therefore the analgesic activity of flupirtine is not based on opiate mechanism. The intracerebroventricular and intrathecal administration of flupirtine and the other analgesics tested showed dose dependent analgesic activity in doses which, when applied systemically, did not cause any analgesia in rats. Thus these substances show cerebral or spinal analgesic activity. In relation to the effective doses (ED50 in micrograms/rat) flupirtine was of the same efficacy in both kinds of administration. Pethidine tested comparatively was found to be less potent by intrathecal than by intracerebroventricular application. On the other hand, morphine was weaker by intracerebroventricular than by intrathecal application. As in the experiments by oral administration, naloxone did not show any effect on the analgesic activity of flupirtine, neither by intracerebroventricular nor by intrathecal application. On the other hand, the analgesic effects of pethidine and morphine were completely suppressed by naloxone. These results demonstrate that the analgesic activity of flupirtine is not caused by the opiate mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyridines↗
PubMed1985

[Increased tendency to seizures as affected by long-term infusions of etomidate in delirium tremens].

A report is given on the clinical trial of the ultra-short-acting hypnotic etomidate for treatment of withdrawal delirium with special reference to delirium tremens. Severe and disturbing side-effects such as myoclonic movements or seizures with equivalent EEG changes compelled discontinuance of the therapy in five of seven patients. The activation of epileptogenic activity in the treatment of delirium tremens by etomidate long-term-infusions and the lack of international experience in this field do not support the use of etomidate as an anticonvulsive agent.

Adult↗
PubMed1984

[The influence on reproduction in rats of DDE mobilization induced by ethanol administration during pregnancy and lactation].

The mobilization of xenobiotics is, in common with their persistence and accumulation, a latent problem of our chemicalized society. Possible sequels connected with the chronic consumption of alcohol were demonstrated by results from animal experiments. After a 10-week exposition to DDE (50 p.p.m. given with the diet), followed by a time of nonexposition, rats were mated and their reproductiveness was brought in relation to the results from residue analyses. Half of the animal received 20% alcohol instead of drinking water during pregnancy and lactation. An alcohol-induced increase in the mobilization of DDE was evidenced on determining residues in the maternal brain, the placentae and the foetus, and also by the excretion in milk and urine. There was a significance increase in prenatal and postnatal mortality (reduced survival index). By analogy to DDT, an oestrogenic action is assumed to be causative.

Adipose Tissue↗
PubMed1984

[Transformation reactions of special metals in organisms and in the environment. 3. In vivo reactions between mercury II chloride and monomethyltin trichloride in rats].

Following the comments on the metabolism and the toxicity of methylmercury compounds as well as on the interaction with food components and a few environmental chemicals from literature study, the results of the in vivo experiments for examining the reaction between HgCl2 and CH3SnCl3 in the gastrointestinal tract and the subsequent distribution of the formed methylmercury are reported. The reaction between both of the substances proceeding in aqueous solution with immediate formation of methylmercury also leads in the intestinal tract very rapidly to the formation of methylmercury and its distribution into various organs. An increase in the relative weight of liver and kidneys was evident.

Animals↗
PubMed1982

Aphakic cystoid macular edema: occurrence in infants and children after transpupillary lensectomy and anterior vitrectomy.

Twenty-seven children and infants underwent surgery for bilateral infantile cataracts. In each infant, the lens in one eye was removed by discission and aspiration, and the other lens was removed by lensectomy and anterior vitrectomy. Ten of 27 eyes undergoing lensectomy and vitrectomy developed aphakic cystoid macular edema; in only one eye that underwent discission and aspiration did macular edema develop. Six of the eyes of the first group developed persistent cystoid macular edema, of which four seem to be visually important. Further long-term studies of the prevalence and functional importance of cystoid macular edema after lensectomy and anterior vitrectomy in children are needed. We do not presently advocate this technique except in the treatment of complicated infantile cataracts.

Aphakia, Postcataract↗
PubMed1982

Leber's congenital amaurosis. Is mental retardation a frequent associated defect?

Thirty-one patients had Leber's congenital amaurosis. Only one was severely retarded, and three demonstrated hypoplasia of the cerebellar vermis on computed tomographic scanning. These findings are in contrast to those of previous investigators, who have emphasized the high incidence of psychomotor retardation associated with Leber's amaurosis. Much of the psychomotor retardation that has been reported is probably secondary to the sensory deprivation and not necessarily a sign of structural CNS dysfunction. The diagnosis of Leber's congenital amaurosis does not, therefore, portend severe intellectual impairment and poor educability.

Blindness↗
PubMed1982

Motility analysis of circularly swimming bull spermatozoa by quasi-elastic light scattering and cinematography.

The Rayleigh-Gans-Debye approximation is used to predict the electric field autocorrelation functions of light scattered from circularly swimming bull spermatozoa. Using parameters determined from cinematography and modeling the cells as coated ellipsoids of semiaxes a = 0.5 micrometers, b = 2.3 micrometers, and c = 9.0 micrometers, we were able to obtain model spectra that mimic the data exactly. A coat is found to be a necessary attribute of the particle. It is also clear that these model functions at 15 degrees may be represented by the relatively simple function used before by Hallett et al. (1978) to fit data from circularly swimming cells, thus giving some physical meaning to these functional shapes. Because of this agreement the half-widths of experimental functions can now be interpreted in terms of an oscillatory frequency for the movement of the circularly swimming cell. The cinematographic results show a trend to chaotic behavior as the temperature of the sample is increased, with concomitant decrease in overall efficiency. This is manifested by a decrease in oscillatory frequency and translational speed.

Animals↗
PubMed1982

[Current status of knowledge on the changes in the hypothalamo-hypophyseo-adrenal cortex system and their effects in chronic alcohol use and withdrawal].

The results of investigations into the changes in the function of the hypothalamus-hypophysis-renal gland system in chronic alcoholics are collated. The review shows that the activity of the hypothalamus-hypophysis-renal gland system is below-normal in at least some alcoholics, but due to conflicting results, it is not possible to decide whether the hypofunction of the adrenal gland is a primary of a secondary effect. The interrelationship between glucocorticosteroids and catecholamines is described and its importance for the adaptability of the organism is stressed. On the basis of the review it may seem advisable to introduce corticosteroid treatment into the therapeutic schema for delerious alcoholic patients and also to apply it on patients with the alcohol withdrawal syndrome if tests show that the function of their hypothalamus-hypophysis-renal gland systems is impaired.

Adrenal Cortex↗
PubMed1982

[Chronic alcoholism and psychological abilities].

On the basis of the experience gained in clinical psychiatry, the works of the last ten years on experimental-psychological efficiency diagnostics with respect to chronic alcoholics are compiled and arranged according to the more important efficiency-psychological scopes. The comparisons that have been made in the quoted, non-selected studies between alcoholics and control groups corroborate that chronic alcoholism leads to a multidimensional damage structure which is test-psychologically provable. In conclusion, factors that may lead to different reductions in efficiency and hypotheses about the connection between chronic alcoholism and efficiency are discussed.

Alcohol Amnestic Disorder↗