Biomedical subjects

L Tkadlecek

Publications and source records attributed to L Tkadlecek.

At least 19 recordsLinked to original sources

PubMed1992

Low survival of mice following lethal gamma-irradiation after administration of inhibitors of prostaglandin synthesis.

An impairment of the survival of mice subjected to whole-body gamma-irradiation with a lethal dose of 10 Gy and treated with a repeated postirradiation administration of prostaglandin synthesis inhibitors (PGSIs), indomethacin or diclofenac, was observed. Morphological examination of the gastrointestinal tract and the estimation of blood loss into its lumen in animals treated with diclofenac did not show serious damage such as haemorrhages or perforation, but revealed structural injury to the intestinal mucosa indicating inflammatory processes. The lesions found are supposed to be connected with increased intestinal permeability which leads to endotoxin escape from the gut and a subsequent increased mortality rate of irradiated animals. It may be concluded that PGSIs are not suitable for the management of radiation sickness after an exposure to lethal doses of ionizing radiation.

Animals↗

PubMed1991

Ultrastructure of erythroblast mitochondria in mice treated with mixtures of radioprotectors.

Unirradiated mice were given i.p. a mixture of mexamine (20 mg/kg body weight) and AET (150 mg/kg body weight) or mexamine (20 mg/kg body weight) and cystamine (150 mg/kg body weight). Acute effects of these mixtures of radioprotective agents on the ultrastructure of basophilic and polychromatic bone marrow erythroblast mitochondria were studied. One hour after injecting mice with above-mentioned mixtures, statistically significant differences in the size of mitochondria were found between control mice and mice given a mixture of mexamine and cystamine. The differences in the number of dilated cristae per micron 2 of the mitochondrion area between control mice and both experimental groups given mixtures of radioprotective agents were also statistically significant. Thus it was proved that also mixtures of radioprotectors induced acute ultrastructural changes of mitochondria which were so far described only after treating mice with only one radioprotective agent.

5-Methoxytryptamine↗

PubMed1990

Changes in hemopoiesis of dying and surviving mice after fractionated irradiation and repeated bone marrow transplantation.

Mice received doses of 3 Gy of 60Co-gamma rays total body irradiation at four-day intervals up to a total dose of 24 Gy. After each dose per fraction half of the animals were injected with 10(6) bone marrow cells. At four- and nine-day intervals evaluations were made of the blood count, bone marrow and spleen cellularities, and spleen mass. In animals subjected only to irradiation the damage of hemopoietic organs was becoming deeper until the end of observation; the majority of these mice died by nine days after the irradiation with the last dose per fraction (by 37 days of the experiment). The authors consider anemia as the main cause of their death. All of the mice that were given bone marrow injections survived; nine days after the last dose of irradiation the mean cellularities of their bone marrows and spleens were 76.8% and 112.3% of the unirradiated controls respectively. In general, regeneration of erythropoiesis was quite successful, the number of thrombocytes was positively influenced, and the number of leukocytes nearly unchanged in bone marrow recipients when compared with the only irradiated mice. We observed two periods of maximum and one of minimum bone marrow and spleen regeneration, which were not synchronized. These results deny an unrepairable damage to the hemopoietic microenvironment in conditions of our experiment. This paper follows up with our preceding work [10] describing results of an experiment which ended on day 24.

Animals↗

PubMed1990

The reaction of lymphatic component of hemopoiesis to fractionated irradiation and repeated bone marrow transplantation.

Mice were repeatedly subjected to individual doses of 60Co-gamma rays at intervals of four days up to total doses of 3, 6, 9, 12, 15, 18, 21 and 24 Gy. Under these conditions, signs of partial adaptation of the lymphatic component of hemopoiesis to conditions of repeated irradiations were found in mice which were given transplants of 10(6) nuclear cells of syngenetic bone marrow after each irradiation. Systematic findings of statistically significant differences in the values of the lymphatic hemopoietic component parameters studied between bone marrow recipients and animals subjected only to repeated irradiations were recorded after 24th day of experiment in mice which received total doses of 21 and 24 Gy. A positive influence of repeated transplantations in bone marrow recipients became manifested in these experimental groups already upon withdrawals made on day 4 after the last irradiation. A quite pronounced increase in the values of the bone marrow recipients' lymphatic hemopoietic component studied was then recorded upon withdrawals made on day 9 after the last irradiation.

Adaptation, Physiological↗

PubMed1989

Haemopoiesis in murine bone marrow and spleen after fractionated irradiation and repeated bone marrow transplantation. I. Erythropoiesis.

Erythropoiesis was studied in mice repeatedly subjected to individual doses of 3 Gy of 60Co gamma-rays at 4-day intervals up to a total dose of 24 Gy on the basis of total bone marrow and spleen cellularity follow-up and analysis of myelograms and splenograms. Half of the mice received 10(6) nuclear cells of syngeneic bone marrow after each fractional radiation dose. It was mainly the spleen which was involved in the adaptation and regeneration of erythropoiesis, its contribution to total erythropoiesis in bone marrow recipients having been as much as 73.9% (day 20 of experiment, total dose 15 Gy). In mice only irradiated, the number of nuclear cells of erythroid lineage decreased to zero values sooner in the spleen (day 16 of experiment, total dose 12 Gy) when compared to the bone marrow (day 24 of experiment, total dose 18 Gy). Analysis of the results of collections made on day 9 after the last irradiation, however, revealed that the haemopoietic microenvironment of the spleen and haemopoietic cells capable of differentiation in the erythroid direction are so resistant to irradiation in only irradiated mice that erythropoiesis in their spleens exhibits signs of regeneration even after the highest total dose of 24 Gy.

Animals↗

PubMed1989

Haemopoiesis in murine bone marrow and spleen after fractionated irradiation and repeated bone marrow transplantation. II. Granulopoiesis.

Granulopoiesis was studied in mice repeatedly subjected to individual doses of 3 Gy of 60Co gamma-rays at 4-day intervals up to a total dose of 24 Gy on the basis of total bone marrow cellularity follow-up and analysis of myelograms and splenograms. Half of the mice received 10(6) nuclear cells of syngeneic bone marrow after each fractional radiation dose. After an initial steep decrease, the number of granuloid cells in the spleen increased about 30-fold between days 12 and 16 of the experiment (total dose 9 and 12 Gy, respectively). This increase was temporary and between days 20 and 24 (total dose 15 and 18 Gy, respectively) a steep decrease again occurred. At a low level (below 10% of the control value) remained the granuloid cells in the spleens of bone marrow recipients until the end of the experiment (day 37, total dose 24 Gy). The behaviour of the granuloid compartment of haemopoiesis thus contrasts with findings in the erythroid compartment (see Hofer et al., 1989b) when high numbers of erythroid nuclear cells remained in the spleens of bone marrow recipients until the end of the experiment. On the whole, the influence of repeated bone marrow transplantation on granulopoiesis in the bone marrow and spleen is positive. Of the 22 comparisons made between bone marrow recipients and mice only irradiated, 14 differences are statistically significant, always in favour of bone marrow recipients.

Animals↗

PubMed1989

Morphology of interactions of the haematopoietic microenvironment with the haematopoietic cells in erythroid spleen colonies.

The morphology of the interactions of the cells of the haematopoietic microenvironment with haematopoietic cells was studied in exogenous erythroid spleen colonies formed in mice, on the fifth and eighth day after their irradiation with a lethal dose of gamma rays and bone marrow transplantation. The characteristic type of stromal cell interacting with less mature cells of the erythroid series was a dark, branching reticular cell. The typical structural interaction of the reticular cells with erythroblasts was the formation of very long, fine cytoplasmic processes by the reticular cells. The processes were in close contact with the erythroblasts and formed a three-dimensional network stretching long distances from the nucleus of the reticular cells. Other cells of the haematopoietic microenvironment, in contact chiefly with poly- and ortochromic erythroblasts, were macrophages and the two together formed typical erythroblastic islands. In places, the macrophages and erythroblasts formed close, firm contacts by means of their cytoplasmic membranes. These morphological observations support the conception that close functional cooperation exists between the cells of the haematopoietic microenvironment and the haematopoietic cells in differentiation and proliferation processes in the haematopoietic tissue of spleen colonies.

Animals↗

PubMed1988

Interstrain differences in the responsiveness of mice to glucan with respect to hematological effects and manifestations of late damage.

A study was made of the effect of a single s.c. injection of 4 mg glucan in the mouse strains C57BL/10, C3H and a hybrid population of mice. In mice of the strain C57BL/10 high responsiveness was demonstrated, manifested in a long-term increase in the granulocyte counts in the peripheral blood. These effects were accompanied by a fall in the mean red cell volume and the mean corpuscular hemoglobin, a fall in body weight, and mortality. 10 weeks after administration of glucan histology revealed necrotic foci in the livers of animals of the C57BL/10 strain, and an increased amount of the fibrous connective component in the pulmonary interstitium. The strain C3H exhibited a low responsiveness in respect of the hematological indices, while the hybrids did not show any significant response.

Animals↗

PubMed1988

A contribution to the study of damage and regeneration of hemopoiesis during fractionated irradiation and repeated bone marrow transplantation.

The experiment was aimed at studying two contradictory actions: damage to hemopoietic organs during application of radiation doses per fraction and regenerative efforts of the organism supported by repeated bone marrow transplantation. The mice received doses of 3 Gy of 60Co-gamma rays total body irradiation at four-day intervals up to a total dose of 18 Gy. After each dose per fraction half of the animals were injected with 10(6) bone marrow cells. At four-day intervals evaluations were made of the blood count, bone marrow and spleen cellularities, and spleen mass. In animals subjected only to irradiation the damage to hemopoietic organs was becoming deeper until the end of observation. In bone marrow recipients the decrease in bone marrow cellularity and the number of leukocytes stopped after day 16, and there was a steep growth of splenic cellularity and mass; the decrease in erythrocyte count stopped on day 20. Obviously a certain recovery of hemopoiesis occurred after the total dose of 12 Gy between days 12 and 16. The lodging of injected hemopoietic stem cells and their proliferation had to be preceded by a regeneration of the hemopoietic microenvironment.

Animals↗

PubMed1987

Effect of indomethacin on the proliferative and differentiation activity in the haemopoietic system of lethally irradiated mice after syngeneic bone marrow transplantation.

The effects of indomethacin treatment on the proliferation and differentiation of haemopoietic stem cells of bone marrow grafts in lethally irradiated mice were investigated. Indomethacin was given subcutaneously, on days 3 to 5 after irradiation, in 6 doses of 0.05 mg per mouse. On day 6 after irradiation, an increased self-renewal of the settled colony-forming cells and an increased amount of differentiated cells were observed in the spleens of the mice treated. Simultaneously, a decreased maturation of the erythroid cells was demonstrated. The effects observed may be explained by the indomethacin-induced inhibition of prostaglandin biosynthesis.

Animals↗

PubMed1987

Interaction of protein- and DNA-loaded liposomes with sperm cells.

Liposomes were loaded with fluorescence-labelled serum albumin and their interaction with mouse spermatozoa was examined in a fluorescence microscope. In the presence of polyethylene glycol 1500, fluorescence became unevenly distributed along the entire body of mature spermatozoa, mostly in the form of aggregates, indicating adsorption of liposomes to the surface of the cells. The fluorescence could be largely removed by washing the cells. In the case of immature sperm cells, fluorescence was evenly distributed on the cells and was not removed by extensive washing, suggesting an internalization of the labelled albumin. A more direct evidence for the entrance of liposome-entrapped macromolecules into the immature sperm cells was provided by autoradiography: radioactivity was found in discrete spots in spermatocytes upon their incubation with liposomes containing isotopically labelled DNA.

Amines↗

PubMed1987

The kinetics of endogenous erythroid haemopoietic spleen colonies in mice between 4 and 10 days after irradiation with doses of 5, 7, or 9 Gy.

The kinetics of post-radiation haemopoietic tissue recovery was studied by evaluating quantitatively the results from histologic studies of the kinetics of endogenous erythroid spleen colony counts in subserial sections of spleens from mice irradiated with 5, 7, or 9 Gy of 60Co gamma-rays at intervals of 4, 6, 8, and 10 days following irradiation. Emphasis was put on individual types of colony-forming cells and on time intervals at which these cells enter into action. Large numbers of rapidly maturing microscopic erythroid colonies appeared between 8 and 10 days after irradiation. From this finding we conclude that in addition to colony-forming cells giving rise to macroscopic colonies, large numbers of already differentiated progenitor cells--the products of the first regeneration wave with a peak approximately 6 days following irradiation--participate in the second wave of regeneration which is typically manifested from day 10 after irradiation.

Animals↗

PubMed1985

A contribution to the morphological study of acute changes in the blood vessels of the central nervous system of rats following irradiation with high-energy (4 GeV/nucleon) helium ions.

Rats were irradiated with helium ions (4 GeV/nucleon; 2 or 4 Gy). After 4-9 hours or three days, a perfusion was performed and sections of the cerebral cortex were investigated under light and electron microscopes. Changes observed in the vessels of the telencephalic cortex are described. Most of the vessels in the sections analysed showed no signs of damage. In some cases there was a dilated perivascular space; a comparison of its occurrence in irradiated and control animals showed a statistically significant increase in frequency of the phenomenon at a shorter interval after irradiation with a larger dose. Electron microscopical analysis showed that the main locality of damage was the border of the perivascular foot of the astrocytes, which exhibited various degrees of edema. The discussion stresses the peculiarities of the interaction of helium ions with living tissues, particularly the heterogeneity of the distribution of absorbed energy. The consequence is in accordance with the nature of the changes observed.

Animals↗

PubMed1985

Delivery of liposome content into plant protoplasts.

The interaction of various types of liposomes with protoplasts of Nicotiana tabacum and Capsicum annuum was studied by means of fluorescence microscopy and autoradiography. The liposomes with a positive charge displayed the strongest affinity to the protoplast membrane, whereas the maximum intracellular delivery of encapsulated protein and DNA molecules into protoplasts was exhibited by the negatively charged liposomes. The results showed that the negatively charged unilamellar liposomes prepared by the reverse-phase evaporation method represent a very promising universal vehicle system for introducing genetic information into plants.

Autoradiography↗

PubMed1985