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Biomedical subjects

K Lapis

Publications and source records attributed to K Lapis.

At least 181 records · Page 10Linked to original sources
PubMed1983

Increased metastatic capacity of Lewis lung tumor cells by in vivo selection procedure.

Lewis lung tumor cells from liver metastases originally obtained from an intrasplenic tumor, and lung metastases obtained from an intramuscular transplant, were repeatedly passaged in the corresponding transplantation sites (spleen, intramuscular). Cells from liver metastases injected into the spleen gained an increased metastatic capacity. The same phenomenon was observed with lung metastatic cells injected intramuscularly, but to a lesser degree. In all passages metastases occurred only in the organs receiving the venous blood from the primary site. The enhanced metastasis formation may be a result of a selection of tumor cells resistant to host cytotoxic cells and/or of selection of tumor cells 'seeding' successfully in target organs.

Animals↗
PubMed1982

Experimental model for liver metastasis formation using Lewis lung tumor.

A new experimental model is introduced for liver metastases using intrasplenically injected Lewis lung tumor cells. The appearance of liver metastases was studied in the presence and after the removal of primary tumor. The tumorous foci in the liver proved to be natural metastases and increased in number blocking the activity of the Kupffer cells by carragheenan. This model provides a useful tool to study different aspects of liver metastases.

Animals↗
PubMed1982

The effect of E-N-L-trimethyllysine (TML) on the humoral and cellular immune response.

E-N-L-Trimethyllysine glutamate (TML) influences the humoral and cellular immune response of mice. Chronic pre- and post-treatment (100 mg/kg/day, 5 times) transitionally increased the anti-SRBC haemagglutinin titre of female CBA mice. After 400 r whole body irradiation, TML treatment accelerated the normalization of the haemagglutinin level. TML treatment prolonged the life-span of BDF1 hybrid mice that had first been immunized and then inoculated with L1210 cells. TML diminished the delayed type hypersensitivity reaction in vivo of irradiated and non-irradiated CBA female mice and dose-dependent decreased the spontaneous (SLMC) and antibody-dependent (ADCC) cytotoxicity of healthy human lymphocytes, in vitro. As a low molecular weight immunomodulant, TML may also be considered as a therapeutic tool.

Animals↗
PubMed1982

HBsAg-like structures in immunosuppressed mice inoculated with human hepatitis B virus.

Thymectomised and irradiated DBA/2 mice were injected intraperitoneally with human serum containing high titer of HBsAg, and were positive for HBsAg. Through the entire experiment neither degenerative and inflammatory lesions nor hepatitis B virus antigens could be detected in the liver of these animals by histomorphology and immunofluorescence, respectively. The sera of all these mice were negative for HBsAg by radioimmunoassay. By electron microscopy, however, increasing amounts of filaments and round particles measuring 20-22 nm in diameter could be observed in the endoplasmic reticulum of the mouse hepatocytes from the 8th day following injection. From the 90th day after inoculation the number of the filaments increased in an extreme degree. After fixation with KMnO4 and EDTA preferential staining, the filaments proved to be highly electrondense. According to the authors the filaments observed in mouse livers are lipoproteins produced by the hepatocytes in response to HBV inoculation. The appearance of the filaments is HBsAg-like, though their immunological characteristics become modified.

Animals↗
PubMed1982

DNA polymerase and thymidine kinase activities in MC-29 virus-induced transplantable hepatoma and the effect of cytostatic treatment of these activities.

The activity of DNA polymerases and thymidine kinase was compared in the MC-29 leukosis virus-induced transplantable hepatoma and in the livers of rats treated with cyclophosphamide (CP), cytosine-arabinoside (ara-C) and 5-fluoro-uracil (5-FU). The specific activity of DNA polymerase was twenty times greater in the MC-29 leukosis virus-induced hepatoma, while thymidine kinase was only 3-5 times greater than in liver. All three enzymes showed Michaelis-Menten kinetics in their substrate and template saturation curves. The template utilization of DNA polymerases from hepatoma and from liver was compared. Both had higher activities on a poly(dA) . poly(dT) template at pH 8.0, than on DNA at pH 7.5. After chromatography on a phosphocellulose column two polymerases were separated. The first peak eluted by 0.15 m KCl preferred DNA as template (polymerase alpha). The second eluted by 0.5 M KCl worked better on poly(dA) . poly(dT) (polymerase beta). Thymidine kinase was eluted by 0.25 m KCl. Inhibition by N-ethylmaleimide (NEM) showed the polymerase alpha to be sensitive and the polymerase beta to be resistant to the sulfhydryl blocking agent; similar to the respective enzymes of other eukaryotic cells. The specific activity of DNA polymerase decreased after CP treatment at 6 h and 72 h and after ara-C treatment at 72 h. The specific activities of thymidine kinase were not changed significantly in response to the drug administrations.

Animals↗
PubMed1982

Combined effect of cytostatic drugs and E-N-L-trimethyl lysine in healthy and transplantable tumor bearing mice.

E-N-L-trimethyl lysine (TML) decreases the toxicity of Vincristin, Cyclophosphamide and Doxorubicin (Adriamycin) when administered simultaneously to healthy mice. Simultaneous treatment of L1210 ascites leukemia bearing mice with 100 mg/kg TML and 2, 2.5, 3.2, 3.5, 4 mg/kg Vincristin or 10-15; 20 mg/kg Doxorubicin increases significantly the survival of the animals when compared with untreated and Vincristin or Doxorubicin treated mice. Repeated impulse treatment of S-180 subcutaneous sarcoma with 100 mg/kg TML and 50-100 mg/kg Cyclophosphamide results in a significantly higher surviving time and surviving rate than Cyclophosphamide treatment alone.

Animals↗
PubMed1982

[Action of N-dinitrosopiperazine and N-nitrosodiethylamine on aquarium guppies].

Tumors and precancerous lesions of the gastrointestinal tract were induced in aquarium fish guppy by dinitrosopiperazine and nitrosodiethylamine dissolved in aquarium water. Nitrosodiethylamine appeared to produce a stronger blastogenic effect than dinitrosopiperazine. Since tumors develop several weeks after exposure to carcinogens, this animal species may be used for express testing nitrosocompounds for blastogenicity.

Animals↗
PubMed1982

Light, fluorescence and electron microscopic observations on vitamin A storing cells in allyl-alcohol induced liver damage.

Earlier studies have described vitamin A accumulation in perisinusoidal Ito cells, but not in portal fibroblasts. The aim of our experiments was to examine whether vitamin A pretreatment is really suitable for the distinction of the two cell groups, and to find out how these cells respond to the periportal injury caused by allyl-alcohol. Using very high doses of vitamin A we demonstrated that the portal fibroblasts, similarly to Ito cells, are able to store vitamin A, therefore in chronic liver injuries, when the lobular and sinusoidal structure is damaged, no difference can be seen between the two groups of cells (using the method suggested by the literature, so far). Our results suggest that both Ito cells and the fibroblasts in the portal region play an important role in the fibrogenesis following allyl-alcohol induced liver injury.

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PubMed1981

Electronmicroscopical detection of iota-carrageenan as its ruthenium red complex.

Specific detection of iota-Carrageenan (i-CAR) at the ultrastructural level has been obtained by coupling with ruthenium red (RR) - an electron microscopic stain. The i-CAR-RR complex showed electron density on carbon layers. Peritoneal macrophages were treated with the complex and after 3 h it caused the same morphological changes in macrophages as iota-Carrageenan alone. On the surfaces of macrophages, fine filamentous electron dense material - the i-CAR-RR complex - was detected.

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