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L Tkadlecek

Publications and source records attributed to L Tkadlecek.

36 records · Page 2Linked to original sources
PubMed1981

A morphological study of continuously irradiated lymphosarcoma cells.

Mouse lymphosarcoma LS/BL cells, cultivated as a free suspension in the peritoneal cavity of C57Bl mice, were continuously irradiated by 60Co unit at an exposure rate of 35.8 x 10(-5) mC kg-1 s-1 (5 R/h). After 250 and 350 weeks of irradiation these cells were examined in light and electron microscope. Both the cytoplasm and the nucleus underwent morphological alterations under continuous exposure. Areas of advanced cytoplasmic degradation were often observed and many nuclei showed wide indentations and prolongation of their shape. The number of mitochondria and vacuoles in the cytoplasm was increased markedly in the irradiated cells. The authors consider some of the described alterations caused by continuous irradiation to act as compensatory mechanisms of the impaired cell.

Animals↗
PubMed1980

Chloramphenicol toxicity in radiation disease.

The effect of chloramphenicol given in high therapeutic doses, in the course of postirradiation syndrome in irradiated mice of C57Bl/10 strain, is reported. Chloramphenicol treatment increased postirradiation mortality of animals and intensified suppression of the proliferating and differentiating processes in hemopoietic organs of the irradiated animals. The results support the assumption that postirradiation depression of hemopoiesis is a contraindication to the therapeutic employment of this antibiotic.

Animals↗
PubMed1978

Electron microscopic morphology of phages of coagulase-negative staphylococci.

Nine phages of coagulase-negative staphylococci were studied carefully with regard to their electron microscopic morphology. Two different groups of phages were detected: the larger phages showed heads of 121 nm diameter on average and tails with 229 nm length and 23 nm width. The smaller phages were characterized with heads of about 76 nm diameter and tails of about 177 nm length and 13 nm width (negatively stained with KPT).

Coagulase↗
PubMed1978

Size and shape of mycoplasma virus MV-Lg-L 172 DNA.

Sedimentation of DNA of mycoplasma virus MV-Lg-L 172 in neutral and alkaline density gradients showed that the chromosome of this virus is most probably formed by a double-stranded circular DNA molecule with a molecular weight of approx. 10(7) daltons. These results were confirmed by direct electron microscopy of the viral DNA. Gamma-irradiation of the virus caused in its DNA single breaks on the average per each 66 eV of absorbed energy. Virus survival depended exponentially on the irradiation dose, D0 being between 60,000 and 70,000 rads. This dose induced on the average one single break in the DNA.

Acholeplasma laidlawii↗
PubMed1978

Study on incorporation of 3H-DNA in the L-cells by means of electron microscopic autoradiography.

Uptake of isologous DNA (labeled with 3H-thymidine) by L-cells was investigated by means of electron microscopic autoradiography. It was found that exogenous 3H-DNA occurred not only in the cytoplasm, but, already from the 1st hr of incubation, permeated as far as in the host cell nuclei. During continuous cultivation, radioactivity established in the nuclei and cytoplasm increases with maximum value after 12 hr incubation. Beginning at the 3rd hr of incubation, in cytoplasma, grain clusters over loci of higher radioactivity were found. After 24 hr incubation, similar grain clusters in L-cell nuclei were observed. In the cytoplasma of the cells, the grains were often determined over or in the vicinity of lysosomes; in the nuclei they were localized predominantly over heterochromatine. The manner of 3H-DNA and 3H-TdR labeling was also compared.

Animals↗
PubMed1976

Properties of the cured oncogenic strain 37400 of Agrobacterium tumefaciens.

The properties of the 37400 oncogenic strain of Agrobacterium tumefaciens are described. This strain was derived from the VI lysogenic strain originally isolated by Hamilton from a Zinnia elegans tumour. Strain 37400 has a number of properties which render it suitable for quantitative and genetic studies. It is cured of prophages and can serve as a universal sensitive indicator for a number of phages isolated from various lysogenic strains of Agrobacterium tumefaciens. Its good growth properties in synthetic media and at elevated temperatues enable the isolation of auxotrophic mutants and temperature sensitive phage mutants. Preliminary experiments show that strain 37400 will serve as suitable starting material for conjugation experiments under defined conditions.

Bacteriophages↗
PubMed1976

Age dependence of the number of the stem cells in haemopoietic tissues of rats.

The number and concentration of haemopoietic stem cells in the femoral bone marrow and spleen of Wistar rats of different ages were investigated. Stem cells were assayed by the spleen colony technique in irradiated rat recipients. The ability of the recipient spleen to harvest transplanted tissue as a macroscopic colony was found to be dependent on the recipient's age. Changes with senescence were observed also in the concentration and the size of the stem cell compartment both in the marrow and spleen. No differences were demonstrated in the seeding of transplanted colony-forming units into the spleen of recipients of 1 and 4 months of age. A rats-mice strain difference in the effect of senescence on the haemopoietic stem cells is discussed.

Aging↗
PubMed1975

Electron-microscopic study of a Mycoplasmatales virus, strain MV-Lg-pS2-L 172.

Morphology and adsorption of a globular virus, lysing Acholeplasma laidlawii were studied in ultrathin sections of plaques in a lawn of the host strain. The virus was globular, about 50 to 90 nm in diameter, with a clearly defined membrane, 6.5 to 8 nm thick. A protuberance about 25 to 35 nm long and 12 to 20 nm thick was observed on numerous virus particles. The evenly granulated, electron-optically dense content of the cells became clearer in cells affected by the viruses. Fibrillar structures of different thickness and small dense areas appeared in cells assumed to be in the preliminary stages of lysis. The interactions in the virus-host system and possible development stages of the virsu are discussed.

Acholeplasma laidlawii↗
PubMed1975

Light and electron microscopy of mouse lymphosarcoma LS/BL cells during the first hour after irradiation with x-rays.

Mouse lymphosarcoma LS/BL cells growing in tissue culture were irradiated with 100, 316 and 1000 R respectively and fixed 5, 15 or 60 minutes later. Semithin sections were studied under a light and ultrathin under an electron microscopes. Under the light microscope, differences between the morphology of individual nuclei were found in all groups, including controls; the rate of their occurrence was without any relation to the irradiation. They may reflect the differences in the state of LS/BL cells which were not completely adapted to cultivation in small glass tubes. On the other hand, the frequency of some ultrastructural changes seen under the electron microscope showed a relation to the irradiation. They were: undulation of the outer nuclear membrane and dilatation of the space between the outer and inner nuclear membranes, slots in karyosomes adjacent to the surface of the nuclei, enlargement of cisternae and vesicles of endoplasmic reticulum and Golgi apparatus. The importance of a careful examination of control groups in such experiments is stressed.

Animals↗