Thy-1 epitopes are expressed on murine myeloid leukemia and reticulum sarcoma cells.

Expression of Thy-1.2 specificities in cells from 29 primary spontaneous leukemias of random-bred ICR Swiss mice was examined by cell membrane and cytoplasmic immunofluorescence with monoclonal HO-13-4 antibody [1]. The Thy-1.2 epitopes were detected in all thymic lymphomas and were absent in the lymphomas of non-thymic origin. Unexpectedly, the Thy-1.2 epitopes were also detected in 71% (5/7) of myeloid leukemias and 40% (4/10) of reticulum cell sarcomas examined.

Calcification of poly(2-hydroxyethyl methacrylate)-collagen composites implanted in rats.

Samples of the polyHEMA-collagen composites with varying collagen content have been implanted into the popliteal region of rats. Three, six and twelve months after the implantation, calcification of the implanted material was determined using a radioactive indicator. At the same time, the implants and surrounding tissue were examined histologically. The degree of calcification of the implants was dependent on the collagen content; it was more pronounced with a higher amount of collagen. The composites with 30% (w/w) or more collagen were biodegraded during the long-term implantation. It is suggested that the composites containing less than 20% (w/w) of fibrillar collagen are used for biomedical applications and that those with a higher collagen content for the in vitro studies.

Influence of heavy metals upon the retention and mobilization of polonium-210 in rats.

PURPOSE: To provide information about the tissue retention and mobilization of the alpha-emitting radionuclide, polonium-210 (210Po), in rats under combined exposure to heavy metal ions and the chelating agent, 2, 3-dimercaptopropane-1-sulfonate (DMPS). MATERIALS AND METHODS: Rats were pre-exposed intraperitoneally to either CdCl2 or Pb(CH3COO)2. 9 or 15 h later they received 210Po nitrate intravenously. The retention and excretion of 210Po via the urine and faeces of pre-exposed rats, as well as in pre-exposed rats treated with DMPS, were followed. The radioactivity due to 210Po in a broad spectrum of body tissues and excreta was measured by the liquid scintillation counting after sample digestion in a mixture of perchloric acid and hydrogen peroxide. The immunohistochemical localization of metallothioneins (MT) was studied using a mixture of murine monoclonal antibodies directed against MT I+II. RESULTS: The present study revealed different tissue distributions of polonium-210 in the rats pre-exposed to lead or cadmium ions when compared with that in 210Po only controls. Under combined exposure to Pb or Cd, the spontaneous excretion of 210Po was enhanced and could be further enhanced by treatment with DMPS. Treatment with this chelator was efficient even when its start was postponed until 24h after internal contamination of the body with 210Po. CONCLUSIONS: Polonium-210 is bound in vivo to binding sites on various biomolecules, among them erythrocytic enzymes and MT. This phenomenon explains the different affinity and overall distribution of 210Po in control body tissues. When the appropriate binding sites are occupied by lead or cadmium, enhanced natural excretion of polonium-210 occurs.

Reduction of subacute lethal radiotoxicity of polonium-210 in rats by chelating agents.

The protective effect of N,N'-di(2-hydroxyethyl)ethylene-diamine-N,N'-biscarbodithioate (HOEtTTC) against the subacute lethal radiotoxicity of polonium-210 was investigated in a survival study and by histopathological and haematological examinations of some organs and tissues in Sprague-Dawley rats. This effect was compared with that of N,N'-diethylamine-N-carbodithioate (diethy dithiocarbamate, DDTC). In the survival study, rats injected in intravenously solely with a lethal amount of 210Po (1.45 MBq kg-1 body mass) died within 14-44 days while 90% of rats treated with HOEtTTC survived for 5 months until sacrificed. When treated with DDTC all rats died within 36-93 days. In the histopathological examination, relevant changes resulting from incorporation of 210Po were found in lymph nodes, thymus and humeral bone marrow. After the treatment with HOEtTTC no pathological changes were observed. In the haematological examination, severe reduction in blood and femoral bone marrow (BM) cell counts was revealed in rats injected with 210Po. This reduction was reversed by treatment with HOEtTTC. Treatment with DDTC led only to partial recovery of blood and BM cell count. In conclusion, under the conditions of the experiment only HOEtTTC was fully effective in reducing subacute lethal radiotoxicity of 210Po.

Effects of magnetic field exposure on the development of lung fibrosis elicited by industrial pollutants.

Lung injury elicited by a single intratracheal instillation of fibrogenic (quartz) and nuisance (anatase) dusts and/or weekly repeated instillation of CdCl2 solution combined with sinusoidal (50 Hz, 10 mT) magnetic field (MF) exposure was studied in male rats. Combined effects in bronchoalveolar lavage (BAL), rat lungs and regional lymph nodes after 4 months of MF exposure (1 h/5 days per week) were evaluated biochemically and by cytological and histopathological examination. Damage of cell membranes in the cell part of BAL due to MF exposure was not observed in the examined animal groups. Following MF exposure, decreased synthesis of collagen proteins (incorporation of [14C]proline) was demonstrated in lungs with quartz dust burden. Histological examination revealed differences in the lung tissue reaction suggesting the modification of the repair process due to MF exposure following experimental injury in both quartz and cadmium groups.

Cell-surface adhesiveness of mouse leukemias.

Cell-surface adhesiveness of forty-one primary mouse leukemias was quantitatively examined by the Latex (polystyrene) particle adherence (LPA) assay. Mean surface adhesiveness of leukemic cell populations was found to be substantially lower than that of normal mouse thymus, lymph node and spleen cell populations. No significant differences were found among mean LPA-positivity of sixteen thymic lymphomas, sixteen reticulum cell sarcomas and six myelogenous leukemias examined; the LPA-positivity of two nonthymic lymphomas and one undifferentiated leukemia was higher and comparable with that of normal mouse thymus cells. Comparison of the LPA-positivity of normal thymus cells and thymic lymphomas indicated that the malignant conversion of thymus cells was either accompanied or followed by a decreased cell-surface adhesiveness.

[Serum lysozyme and copper levels in rats after the administration of dust]. / Obsah lyzozýmu a medi v sérech potkanu po podání prachu.

Changes in the content of lysozyme and copper were studied in the blood serum of rats in four time intervals (1, 2, 12, and 24 weeks) after administration of 50 mg TiO2, Sio2 or coal dust and the copper content was also studied 12 weeks after administration of 3 industrial dusts. The obtained results were supplemented by histopathological examinations and in the 12-week interval by the determination of the lung wet weight. The lysozyme content was statistically significantly increased compared to controls practically over the whole time course with differences in the level of the response to SiO2 in comparison with the response to TiO2 and coal. With the exception of the first interval, the serum copper level was statistically significantly increased only after quartz dust administration. The obtained results were compared with literary data and findings reported from clinical practice.

The use of the DENTACRYL rapid (Spofa) resin for preparation of the rat tracheobronchial casts.

We have made tracheobronchial casts of the rat lungs using DENTACRYL Rapid (Spofa)--the synthetic methacrylic resin of Czechoslovak origin. The details of the method are fully described. The differences between preparations of the intact rat tracheobronchial trees and those of the rats after quartz instillation are illustrated. These differences are analogous to the commonly described changes in bronchograms.