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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↗
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↗
PubMed1976

Time course and disposition of fucose radioactivity in rat hippocampus. A biochemical and microautoradiographic study.

Male adult rats were injected intraventricularly with L-[1-3H]fucose. At various intervals, ranging between 30 min and 11 days, one-half of the brain was prepared for microautoradiography, and the hippocampus from the other side was prepared for biochemical investigations. The TCA-precipitable proteins from the hippocampus homogenate were maximally labeled at between 8 and 24 h and remained at a high radioactivity level even 11 days after [3H]-fucose injection, the labeling being predominantly present in the solubilized insoluble proteins. Using gel electrophoretic separation, study of Tris-soluble material indicated a rapid turnover of soluble fucose-containing glycoproteins, whereas several slow-migrating bands of solubulized proteins revealed a time course suggesting the presence of fucose-containing glycoproteins with slower turnover rates. Using microautoradiography, a rapid labeling of neuronal cell bodies of the hippocampus was found, whereas the nuclei were not labeled. Perikarya were maximally labeled 4 h after [3H]fucose application. The radioactive material was continuously transported from the soma into the corresponding fiber layers, the latter being maximally labeled at a pulse interval of one day; even 10 days later a considerable amount of radioactivity could be detected in the neuropil.

Animals↗
PubMed1976

Increased fucose incorporation into rat hippocampus during learning. A biochemical and microautoradiographic study.

The incorporation of intraventricularly infected L-[1-3H]fucose into proteins of the hippocampus and visual cortex was studied during the acquisition of a shock-motivated brightness discrimination in rats. The labeling of Tris-soluble proteins from both regions was not significantly changed during learning, whereas solubilized insoluble proteins obtained from the hippocampus revealed an increased fucose incorporation in learned animals. A significant enhanced incorporation into some distinct, slow-moving, carbohydrate-rich protein bands, separated by polyacrylamide gel electrophoresis, was observed in material from CA1 and CA3 sectors as well as from area dentata of the hippocampus formation during acquisition. The corresponding gel bands from the visual cortex exhibited no differences between trained animals and controls. Jointly performed microautoradiography showed an increased fucose incorporation into most areas of the hippocampus in learned animals compared with active and passive controls. The most significant differences were found to occur mainly in substructures consisting of densely packed neuronal cells.

Animals↗
PubMed1976

Electrophoresis of water-insoluble leptospiral proteins and the taxonomy of Leptospira.

The cellular debris obtained after lysis of Leptospira were solubilized by sodium dodecyl sulfate and studied by polyacrylamide electrophoresis, comparing the molecular weight and relative concentration of the protein bands. The percentage similarity of 30 characteristic bands from 21 Leptospira strains, belonging to the main pathogenic and some saprophytic serogroups, was calculated; A partial matching of the derived dendrogram with the other classifications was observed.

Bacterial Proteins↗
PubMed1976

Changes in labeling of soluble and solubilized hippocampus proteins after a learning experiment in rats.

At various intervals after acquisition of a brightness discrimination in rats labeled leucine was intraventricularly applied. Hippocampus tissue was fractionated in soluble and solubilized insoluble protein fractions. Protein content and labeling of several electrophoretically resolved bands showed a biphasic time course: a first increase was observed 20 minutes after training including preferably soluble proteins, whereas a second increase (about eight hours after training) was mainly related to solubilized insoluble proteins.

Animals↗
PubMed1975

Changes in labeling of soluble and solubilized rat brain proteins using (3H)-leucine as precursor during a learning experiment.

This paper deals with an electrophoretic study on soluble and solubilized rat brain proteins during a brightness discrimination. After intraventricular injection of L-[3H]-leucine the most pronounced increase in relative specific activity was found for several soluble acidic protein-band complexes as well as for solubilized slow-migrating non-myelin proteins obtained from hippocampus of trained animals over the data obtained for active and passive controls.

Animals↗
PubMed1975

[Reliable micromethod for determination of the protein content in tissue homogenates].

A micromodification for protein determination in tissue material using Amido black 10 B is described. Compared with the method of LOWRY et al. it requires a comparable time expenditure, but has three principal advantages: 1) it is 5-10fold more sensitive; 2) the calibration curve is linear over a virtually unlimited range; 3) it is feasible in the presence of a number of substances frequently used in protein analyses and making difficult or impossible measurement according to LOWRY et al.

Animals↗