[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.

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.

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.

[Application of implants for dental prostheses in indications for complete dentures. 2]

An interesting clinical case of fixed dental prostheses is described, performed via Bulgarian bioceramic intraosseous implants and two retained teeth on the upper jaw, i.e. indications for complete prostheses in a 38-years old female patient. The case has been solved in a way so that when necessary (retention of implants) guarantees a removable prosthesis with Bulgarian traverse-joint elements.

[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.

[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.

[Articular-telescopic bridge prosthesis on loose teeth]

A clinical case is described for removable articulartelescopic bridge prosthesis of a defect, restricted distally by loose teeth (II degree of pathological looseness) and 3/4 atrophy of the alveolar bone. Compromised prosthesis has been realized by restriction and equalizing the mobility of the bridge-carriers by an articular and telescopic connection. Bulagarian articular elements have been used (TCE) for a soft contact and stabilization and sinking conical telescopes.

[Central incisors--implants]

Two clinical cases are presented in the paper with one of the most common defects of dentitions as an indication for implantation-prosthesis--the absence of the upper central incisors as a results from acute trauma. A good functional and aesthetic effect has been attained. The constructions are in good order and have no changes in the teeth and implants during the almost two-year period.

Changes in activities of fucokinase and fucosyltransferase in rat hippocampus after acquisition of a brightness discrimination reaction

Activities of enzymes involved in utilization of the glycoprotein precursor L-fucose (fucokinase and fucosyltransferase) were studied in rat hippocampal tissue after acquisition of a brightness discrimination reaction. Fucokinase activity was increased immediately after training, while fucosyltransferase revealed decreased values. However, 7 hr after training fucokinase activity showed normal values, while fucosyltransferase activity rose in trained animals over active and passive controls. The results are discussed in the light of a regulatory role that fucokinase and fucosyltransferase may play in fucose utilization under altered functional conditions.

Distribution of hippocampal glycoproteins as demonstrated in rats by lectin binding and autoradiography after intraventricular injections of labelled fucose, N-acetyl-glucosamine and mannose

The present study demonstrates distinct distribution patterns of glycoproteins in rat hippocampus, with respect to synthesis from precursors (autoradiography) and endogenous contents (lectin binding). The autoradiographic analysis performed 1, 2, 8 and 24 h after intraventricular injections of tritium-labelled L-fucose. N-acetyl-D-glucosamine and D-mannose revealed that up to 2 h after application of any of the three precursors, radioactivity occurred in the pyramidal and granular cell layers. Afterwards, however, rapid migration of label proceeded from the cell bodies into the neuropil after application of fucose and acetylglucosamine, while after injection of mannose a considerable amount of radioactivity stayed in the cell body layers, even 24 h after administration of labelled precursor. These findings were consistent with the histochemical visualization of glycoprotein constituents by fluorescent wheat germ lectin (preferentially binding to glucosaminyl residues) and concanavalin A-horseradish peroxidase (preferentially binding to mannosyl residues). These showed a heavy staining predominantly in neuropil and somata, respectively, with concanavalin A-binding giving more distinct patterns than the application of labelled mannose. The usefulness of the three glycoprotein precursors as correlates with functional behavioural changes in discussed.

Mechanisms of dopamine induced changes in hippocampal glycoprotein metabolism

In rat hippocampal slices incubated in the presence of dopamine, a relatively strong correlation was observed between changes in the incorporation of 3H-fucose into total proteins and the formation of GDP-3H-fucose. However, in hippocampal homogenate the incorporation of 14C-fucose from GDP-14C-fucose was not stimulated by dopamine. In contrast, the incorporation of 3H-fucose was stimulated by dopamine to a similar extent observed in hippocampal slices. Furthermore, in hippocampal slices dopamine did not increase the activity of fucosyltransferase. These results, together with our previous findings, suggest that the increased incorporation of fucose induced by dopamine in the hippocampal slices may be due to a receptor-mediated cAMP-dependent regulation, which controls the rate of fucosylation of acceptor-glycoproteins either at the level of fucose phosphorylation or of formation of GDP-fucose rather than the activity of fucosyltransferase.

Effect of L-fucose on brain protein metabolism and retention of a learned behavior in rats

The intraperitoneal or intraventricular application of L-fucose (100 mg/kg or 75 microgram, respectively) prior to training in shuttle box avoidance as well as in shock-motivated brightness discrimination in rats significantly improved the retention of learned behavior 24 hr later. The application of D-fucose was without influence on retention. In naive animals, intraventricularly applied L-fucose (75-200 microgram) caused an increase in the rate of protein synthesis in the hippocampus, resulting in a significant increase in total proteins of this brain structure, mainly attributed to the Tris-insoluble protein fractions. The results are discussed in terms of an activation of glycoprotein formation by increasing supply with L-fucose.

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.