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Biomedical subjects

N Popov

Publications and source records attributed to N Popov.

At least 19 recordsLinked to original sources
PubMed1990

Metabolization of a retention-improving dosage of methylglucamine orotate in rat brain.

The present study was carried out to investigate the time course of metabolization in brain and the influence on RNA synthesis of a retention-improving dosage of methylglucamine orotate after intracerebroventricular application. As determined by the HPLC technique, 73% of acid-soluble radioactivity were recovered in unmetabolized orotic acid 30 min after injection of 1 mumole methylglucamine [6-14C]orotate. Two hours later the amount of radioactivity found in this compound was negligible. Analysis of the sequence of labelling of uridine compounds revealed uridine to be the metabolite exhibiting the highest radioactivity at 30 min, whereas UMP- and UDP-sugars attained their maximum 90 min after injection of the precursor. Incorporation of [3H] guanosine into brain RNA was not altered by intraventricular application of 1 mumole methylglucamine orotate as compared to methylglucamine chloride-treated controls. The results are interpreted in the light of behavioural findings in which the pyrimidine nucleotide precursor at the dosage used improved the retention performance of an acquired behaviour in the rat.

Animals↗
PubMed1990

[A dental concept in gerontology].

The necessity of gerontal dental care programme will be caused by statistical datas. The mainpoints of this prophylactically orientated care programme are described.

Aged↗
PubMed1990

Effects of intraventricularly applied methylglucamine orotate on [3H] acetylglucosamine incorporation into rat brain tissue during a learning experiment.

The present work was undertaken to study the influence of intraventricularly applied methylglucamine orotate (MGO) at a memory-facilitating dose of 1 mumole vs. 1 mumole methylglucamine chloride (MGCl) as a control substance on the incorporation of intraventricularly injected [3H]acetylglucosamine into rat hippocampus and striatum plus thalamus. MGO or MGCl were applied 50 min prior to application of labelled aminosugar, the incorporation times being 1, 4 and 24 h. In non-trained animals, MGO produced an increased labelling of hippocampal proteins (20%) after 24 h, whereas labelling of the lipid fraction was virtually not altered. In trained animals (brightness discrimination model), the increase in labelling caused by MGO in hippocampal proteins was more marked (49%), and an even higher increase in labelling was noted for the hippocampal proteins was more marked (49%), and an even higher increase in labelling was noted for the hippocampal lipids (63%). The second brain region under investigation, striatum plus thalamus, showed no MGO-induced alterations in labelling. The findings are discussed in the light of the working hypothesis of the functional role of macromolecular changes occurring mainly in the hippocampus during memory formation.

Acetylglucosamine↗
PubMed1989

Influence of dopamine receptor agonists and antagonists on calmodulin translocation in different brain regions.

Acute and chronic experiments were performed to study the effects of intraperitoneally administered dopamine receptor agonists and antagonists on the translocation of cytosolic and membrane-bound calmodulin in the striatum and hippocampus of the rat brain. Single doses of apomorphine and a low-dose amphetamine (1.25 mg/kg) resulted in a translocation of calmodulin, as measured by a decrease in membrane-bound and increase in cytosolic calmodulin in the striatum, whereas bromocryptine was ineffective. Amphetamine exerted a similar effect in the hippocampus and striatum. However, a high-dose amphetamine (5 mg/kg) had an opposite effect on translocation, in that there was an increase in membrane-bound calmodulin. Chronically applied amphetamine (5 mg/kg) and haloperidol (1 mg/kg), i.e. under conditions of dopamine receptor supersensitivity, tended to decrease cytosolic calmodulin in the striatum and hippocampus, and to increase membrane-bound calmodulin. The findings and, especially, the chronic effects of haloperidol and the high dose of amphetamine are interpreted in the light of the current concept which suggests that transmitters and intraneuronal signalling systems converge, thereby influencing the more complex processes of neuronal plasticity, rather than receptor sensitivity only.

Amphetamine↗
PubMed1989

[In vitro cytotoxicity of melanoidins isolated from cooked meat and fish samples].

A study has been undertaken to investigate the biological activity of melanoidins isolated from meat samples baked according to Kuntscheva (electro-baking oven, 200-300 degrees C, 60-210 min) and from semi-finished meat products baked in swimming fat (200 degrees C, 3 X 50 min, repeated use of the oil) as well as from semi-finished fish products (190 degrees C, 60 min). A weak toxicity of the melanoidins formed within a longer thermal treatment, but no mutagenic effect was stated. The cytotoxic alterations showed no specific character.

Animals↗
PubMed1989

Effects of intraventricularly applied gangliosides and N-acetylneuraminic acid on acquisition and retention performance of a brightness discrimination task in rats.

The effects of intraventricularly applied gangliosides (about 90 to 120 nmoles/10 microliters) and N-acetylneuraminic acid (800 nmoles/10 microliters) on acquisition and retention of a brightness discrimination task were studied in rats. Single injection of GT1b and N-acetylneuraminic acid improved the retention performance. GM1 showed an enhancing effect on both acquisition and retention, while GD1a and GD1b exerted no influence on the behavioral parameters tested. The findings presented show how memory may be improved by exogenous application of substances commonly occurring in the mammalian body.

Animals↗
PubMed1989

Effects of intraperitoneally applied D-galactosamine on uridine and cytidine plasma content and brain activity of uridine kinase in the rat.

As determined by the HPLC technique, injection of 1.85 mmoles/kg D-galactosamine caused strong alterations in the plasma level of cytidime. Thus, 2 h and 4 h after application of the amino sugar only 54% and 61%, respectively, of the normal values were measured, while an increase to 135% of controls was observed 24 h later. In contrast, intraperitoneal application of D-galactosamine had no influence on the plasma level of uridine. The activity of the enzyme, uridine kinase, in the hippocampal area of the rat brain was increased 2 h and 4 h after D-galactosamine treatment. The results are discussed in the light of behavioural findings in which intraperitoneally applied D-galactosamine at this dosage improves the retention performance of an acquired behaviour in the rat.

Animals↗
PubMed1989

[Exchangeable system synthetics-rider at the bridge-joint prosthetics].

In order to improve the prosthetic supply, a clam-on system for bar-joint-mandibular dentures has been developed. When replacing clamp No. 1 by clamp No. 2 both the vertical translation and the frontal rotation of the prosthesis are ensured over a longer time of function. Placing at disposal ready-made plastic bar-joint elements facilitates the clinic and the laboratory technology for making the bar-joint-mandibular denture.

Denture Design↗
PubMed1988

Alterations in calmodulin and S-100 protein content of hippocampal slices during long-term potentiation.

The content of calmodulin and S-100 protein in fractions of rat hippocampal slices was assayed by solid phase radioimmunology and radial immunodiffusion, respectively. One hour after tetanization (electrical stimulation of area dentata granular cells and recording from CA3 pyramids) an inverse translocation of these Ca++-binding proteins was observed: an increase in the calmodulin content in the water-soluble and a decrease in the Lubrol-soluble fractions, while an increase in S-100 protein in the Triton-soluble and a decrease in the water-soluble fractions occurred. The results are suggestive of a regulatory function of these proteins in events during repetitive stimulation of a synaptic input. The calmodulin increase in the cytosolic compartment may reflect the involvement of Ca++-calmodulin dependent intraneuronal metabolic processes underlying the induction and/or temporary maintenance of neuronal functional changes occurring after repeated or intense synaptic activity. The elevated S-100 protein level in the membrane compartment might be interpreted in terms of functionally induced redistribution in that neuronal cells are provided with additional amounts of S-100 protein originating from the surrounding glial cells which store large amounts of soluble S-100 protein.

Animals↗
PubMed1988

A biochemical and immunohistological study of calmodulin in rat brain structures.

Calmodulin content and immunoreactivity in rat brain structures, believed to be essential site involved in plasticity events, were determined by using biochemical and immunohistochemical methods, respectively. The levels of cytosolic and membrane-bound calmodulin paralleled the overall distribution pattern of calmodulin immunoreactivity. Very intense immunoreactivity was observed in neuronal structures of hippocampus, striatum and mesencephalon. White matter structures and, especially, myelinated nerve fibres did not reveal calmodulin immunoreactivity. Thus, the present findings are consistent with data reported in the literature that calmodulin, unlike to other calcium-binding proteins, is primarily associated with neuronal elements. The present findings support the usefulness of calmodulin studies in elucidating of cellular mechanisms underlying neuronal plasticity.

Animals↗
PubMed1988

Alterations in calmodulin content of rat brain areas after chronic application of haloperidol and amphetamine.

The water-soluble (cytosolic) and Lubrol-soluble (membrane-bound) calmodulin contents were determined radioimmunologically in fractions of striatum, hippocampus and cerebellum of dopamine supersensitive rats. Development of supersensitivity was the sequel of 3-weeks treatment of the animals with 1 mg/kg haloperidol or 5 mg/kg amphetamine i.p. daily. In the dopamine-rich striatum, the membrane-bound calmodulin content was increased by both modes of treatment, consistent with data from the literature. The patterns suggest that additional calmodulin was synthesized under the conditions studied. The hippocampus, the region poor in dopamine while playing an essential role in learning and memory formation processes, revealed similar patterns after both modes of treatment. However, in this region a pronounced translocation was seen, i.e. a redistribution from the cytosolic into the membrane compartment, without signs evidencing enhanced synthesis. The third region under investigation, the cerebellum, did not show any alterations in calmodulin content. Differentiation between pre- and postsynaptic changes was not possible. The results are discussed in the light of the present knowledge about participation of dopaminergic systems in processes of neuronal plasticity.

Amphetamine↗
PubMed1985

Effects of D-galactosamine and D-glucosamine on retention performance of a brightness discrimination task in rats.

The glycoprotein and ganglioside precursors D-galactosamine and D-glucosamine were tested for effects on acquisition and retention of a brightness discrimination reaction in rats. Intraperitoneally (1.85 mmoles/kg) and intraventricularly (0.8 mumoles) applied D-galactosamine had no influence on acquisition, but improved the retention performance. Intraperitoneally (6.0 mmoles/kg) and intraventricularly (2.4 mumoles) applied D-glucosamine showed qualitatively identical results, i.e. improving effect on retention performance. The penetration abilities of [3H]D-glucosamine and [3H]N-acetyl-D-glucosamine to cross the blood-brain barrier were tested: D-glucosamine penetrated easily the blood-brain barrier (approximately 2:1 relation). However, after intravenous application of 200 mumoles 30 min before training both substances showed a positive effect on retention performance. The findings are discussed in the light that the retention-improving effects of the hexosamines under investigation are believed to be due to a direct, activating influence on glycoprotein and/or ganglioside syntheses in the brain.

Amino Sugars↗
PubMed1985

Effects of carbohydrate precursors of glycoproteins on retention performance of a brightness discrimination task in rats.

The influence of intraventricularly applied carbohydrate precursors of glycoproteins on acquisition and retention of a brightness discrimination task in rats was tested. The injection of 0.8 mumoles L-fucose/animal, N-acetylneuraminic acid or D-galactosamine as well as 2.4 mumoles/animal D-galactose or D-glucosamine 30 min before starting the behavioural experiments significantly improved the retention performance of the acquired behaviour. The intraventricular application of 2.4 mumoles D-mannose/animal had no influence on the behavioural parameters tested. The results are discussed in the light of an activation of glycoprotein formation in brain tissue mainly by carbohydrates which occupy terminal positions in the oligosaccharide chains.

Animals↗
PubMed1979

Fucose incorporation into rat hippocampus structures after acquisition of a brightness discrimination. A histoautoradiographic analysis.

Using a brigthness discrimination model in rats, the labeling of discrete hippocampus formation structures was studied after intraventricular application of [3H]-fucose. This substance was injected 5 min before training as well as 5 min, 3, 7 and 23 h after training, the pulse period lasting 120 min in all cases. A significantly training-related enhanced labeling of CA1, CA3 and CA4 cell bodies and fibres revealed that a biphasic time course occurring when radioactive fucose was applied 5 min before training and 7 h after training, whereas the increased labeling of area dentata structures was evidenced only after application of radioactive fucose 5 min before and after training. In all structures under investigation the training-related increase in labeling was more pronounced in the fibre layers than in the pyramidal and granular cell bodies.

Animals↗