Search PubMed⌕ Search

Biomedical subjects

M Ledvina

Publications and source records attributed to M Ledvina.

At least 55 records · Page 3Linked to original sources
PubMed1981

Interaction of a tropoelastin model with connective tissue components.

It has been suggested that tropoelastin interacts with macromolecular components of connective tissue during the formation of elastic fibers. alpha-Elastin, used traditionally as a model of tropoelastin and mature elastin, is not suitable for the monitoring of this interaction in vitro. Therefore a new model of tropoelastin, the methyl ester of alpha-elastin, was synthesized and the interaction of this modified elastin with hyaluronic acid, chondroitin sulfate, proteoglycan subunits, solubilized structural glycoproteins and collagen was studied by turbidimetric measurement. Results indicate that alpha-elastin methyl ester is a better model of tropoelastin than alpha-elastin especially in those experiments where ionic interactions are believed to occur. It was also found that alpha-elastin methyl ester formed aggregates with hyaluronic acid, chondroitin sulfate, proteoglycan subunits and solubilized structural glycoproteins at room temperature and under conditions close to physiological ones. Alpha-elastin does not interact with these compounds under similar conditions. The character of the bonds involved in the interaction and the possible biological significance of the experiments are discussed.

Animals↗
PubMed1980

Interaction of alpha-elastin with ionic detergents.

Coacervation is known to be a fundamental step in elastogenesis that is influenced by various naturally occurring substances in connective tissue. Therefore, interaction of alpha-elastin with ionic detergents (sodium dodecyl sulfate, dodecylbenzyldimethylammonium bromide, cetyltrimethylammonium bromide, pentadecacarbethoxytrimethylammonium bromide and cetylpyridinium bromide) was studied as a model for the elastin interaction with amphipilic substances. The course of the interactions was followed by the effect on thermal coacervation, solubilization of lipophilic dye, difference spectra measurements and fluorescence probe. The results indicate that the detergents examined interact with alpha-elastin below critical micelle concentration in two different ways. In the first case, a mixed micelle can be formed from the detergent molecules (SDS, DBD) and alpha-elastin: alternatively mixed micelles are not formed, but the detergent molecules (CT, PCT, CP) do interact with elastin. The interaction of alpha-elastin at the isoelectric point was found to depend more on the chemical structure of the detergent molecule than on its charge. If detergent concentrations above the critical micelle concentration were applied, the interaction mechanism was different from that observed at lower detergent concentration.

Animals↗
PubMed1980

Influence of radioprotective agents on the activities of isoenzymes of blood serum alkaline phosphatase in irradiated dogs.

Changes of the total serum activity of alkaline phosphatase (AP) and its bone and intestinal isoenzymes were studied in dogs gamma-irradiated by 3.0 Gy. The activities of AP isoenzymes were determined by means of a heat inactivation-inhibition method. After irradiation the serum AP activities were lower in general. In case of the bone isoenzyme the decrease was most pronounced. The changes of the total AP activity and of the intestinal isoenzyme were less distinct. The i.m. administration of the radioprotective mixture cystamine with mexamine (24 mg/kg + 4 mg/kg) before irradiation led only to a moderate reduction of the radiation-altered AP values in the dogs. The present results indicate that the radioprotective way used here renders only an unsatisfactory protection for large laboratory animals against ionizing radiation.

5-Methoxytryptamine↗
PubMed1980

The concentrations of SH-groups in some radiosensitive tissues after the administration of radioprotectors in rats.

The changes in the concentrations of total, nonprotein and protein SH-groups were spectrophotometrically determined in the small intestine and bone marrow of the rats 10, 20, 30 and 60 min after the administration of protective doses of cystamine (50 mg/kg), mexamine (10 mg/kg) or of a mixture of cystamine with mexamine (20 + 10 mg/kg). Cystamine caused an increase in the concentration of mainly nonprotein thiols, whereas the mexamine administration increased the protein SH-groups (mainly between the 20th and 30th min after treatment). The radioprotective mixture led to the most pronounced increase at the 10-min interval. This increase at the 10- and 20-min intervals was more pronounced (or identical) than after cystamine or mexamine administered as a single agent. If the SH-concentration should correspond to the degree of radioprotection, then the phenomenon observed would indicate the usefulness of the mixture administered.

Animals↗