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Biomedical subjects

N Popov

Publications and source records attributed to N Popov.

At least 55 records · Page 3Linked to original sources

Visualization of rat brain glycoproteins in polyacrylamide gels by means of concanavalin A-peroxidase.

A reliable method for visualization of mannose-containing glycoproteins in electrophoretically (SDS-PAGE) separated Tris-soluble, Triton-soluble and Triton-resistant fractions obtained from rat hippocampus, brain region supposed to play an essential role in learning and memory processes, was elaborated. The method is based on the Concanavalin A-horseradish peroxidase reaction applied successfully for the purpose of light and electron microscopic visualization of cellular carbohydrate components.

Animals↗

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↗

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↗

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↗

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↗

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↗

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↗

[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↗

Changes in labeling of soluble and insoluble rat brain proteins using [3H]-tyrosine as precursor during a learning experiment.

The incorporation of intraventricularly injected L-[3H]-tyrosine into proteins from three rat brain regions was studied during the acquisition of a shock-motivated brightness discrimination. Separating the proteins by means of polyacrylamide gel electrophoresis revealed an increased labeling confined to only a few of the resolved slow-moving bands of soluble and, especially insoluble hippocampus proteins. The labeling of visual cortex proteins showed only minute changes, while the auditory cortex proteins exhibited no differences between trained and nontrained animals.

Animals↗