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Biomedical subjects

G Neupert

Publications and source records attributed to G Neupert.

At least 55 records · Page 3Linked to original sources
PubMed1982

Effect of thrombin on glycosaminoglycans in fibroblast cultures.

Embryonic rat fibroblasts were incubated with thrombin of different concentrations for 48 hrs. in the absence of calf serum. Cell proliferation was increased in dense cultures only. In low and high density cultures there were increased glucose consumption as well as increased GAG turnover rates and GAG total concentration. In the GAG distribution pattern DS was decreased, but HA was increased in low density and CS in high density cultures. The possible correlation between CS increase and cell proliferation is discussed.--Experiments with plasmin were without stronger effects on the fibroblast cultures.

Animals↗
PubMed1982

Experimental tumors with features of malignant fibrous histiocytomas. Light microscopic and electron microscopic investigations on tumors produced by cell transplantation of an established fibrosarcoma cell line.

An established fibrosarcoma cell line (RFS) derived from a cadmium induced fibrosarcoma of rat and RFS-cells in different subcultures produced tumors in nude mice and baby rats which showed characteristics of fibrosarcoma, malignant fibrous histiocytoma and completely undifferentiated sarcoma. After thorough examination of cells in culture and in experimental tumors by light microscopic and electron microscopic methods that conclusion has been drawn that malignant fibrous histiocytoma can develop from fibrosarcoma. By this the assumption that malignant fibrous histiocytomas derive from tissue histiocytes is questioned. After the discussion of the general unspecifity of the storiform growth pattern and the cytology of malignant fibrous histiocytomas the idea is presented that many defined malignant soft tissue tumors inclusively fibrosarcomas may pass a phase which should morphologically be diagnosed as malignant fibrous histiocytoma. Conceding the practical value of this diagnosis we emphasize that the concept of the entity "malignant fibrous histiocytoma" should be critically reevaluated because of the probable heterogeneity of this tumor group.

Animals↗
PubMed1982

[The system of intermediate filaments in the cells of the epitheloid line RL 19. An electron microscopy study].

The occurrence and distribution of intermediate-sized filaments (100 A filaments) in an established epitheloid cell line RL 19 originally derived from rat liver was described by use of ultrathin sections tangentially and crossly to the cell substrate. The epithel-like cells showed in the cytoplasm a highly developed system of intermediate-sized filaments. The intermediate-sized filaments are either individually traversing in different directions or are grouped to loosely arranged bundles randomly running wavy-like through the whole cytoplasm. The bundles of highly variable thickness (20 to 40 filaments) are branched or are uniting and assembled to a three-dimensional network. The nucleus and Golgi-system are surrounding by a large ring of densely packed intermediate-sized filaments. Occasionally parallel running single filaments are associated to electron dense aggregates.

Animals↗
PubMed1980

Toxicity evaluation of water soluble substances of dental materials by means of cell population in vitro.

The paper describes a method of evaluation of the biocompatibility of dental restorative materials with a monolayer cell culture system. Semisolid and solid materials were eluted under physiological conditions. The cell monolayer was exposed to the eluates. The method enables the recognition of toxic ingredients and thus their elimination by the producer of these materials as well as the comparison of the cytotoxicity of newly developed materials with conventional ones.

Animals↗
PubMed1980

Myofibroblasts in connective tissue capsules around implanted dental materials.

For testing the biocompatibility of dental materials in an experimental animal model the capsular tissues around the implanted dental materials were examined light and electron microscopically. The exudative inflammation and fibrosis at different times after implantation were thought to be the indicators of the degree of the compatibility. Starting from the knowledge of the occurrence of myofibroblasts in reparative granulation tissue we looked for such cells in the capsular tissues. Myofibroblasts were especially found at three weeks after onset of the experiments. Structural peculiarities of this fibroblast modulation are emphasized. Myofibroblasts are considered as an essential link between the early exudative reaction and the late fiber formation in tissue reactions after mechanical injury.

Animals↗
PubMed1979

[Biological responses to filling materials with special reference to the composite material evicrol--an experimental study (author's transl)].

The biological responses to the composite filling material Evicrol were tested by temporarily differentiated implants in rats. Type and degree of the inflammatory reaction as well as the intensity of connective tissue fiber formation were used as criteria for evaluation of the histocompatibility of the subcutaneous implants. As compared to other composite filling materials, Evicrol was found to produce a relatively severe irritation of the tissue. In comparison with silicate cements and also with silicopolyacrylate cement, composite materials including Evicrol were responded to by for less pronounced chronically toxic effects.

Composite Resins↗
PubMed1978

Killing of untreated target cells by nonimmunized rat macrophages in vitro. I. Studies on the type of effector cells and their capacity to destroy allogeneic target cells.

Spleen cells derived from unsensitized Wistar rats lysed untreated, allogeneic liver cells of high passages (93rd until 159th subculture) as well as allogeneic tumor cells in mixed cultures. On the other hand, rat liver cells between passages 42 and 56 and allogeneic or xenogeneic fibroblasts were not destroyed by rat spleen cells in vitro. The degree of target cell lysis was dependent on the incubation time and effector-target cell ratio. In the rat spleen, the macrophages were detected as effector cells. Rat peritoneal cells showed the same effects as rat spleen cells. Trypsin treatment caused no loss of cytotoxicity of rat macrophages. Thymocytes and blood lymphocytes of rats were not cytotoxic against allogeneic or xenogeneic target cells. The macrophages apparently destroyed target cells by a nonphagocytic form of cell contact. Unstimulated spleen cells of guinea pigs, Syrian hamsters, CBA mice and rabbits were not capable to destroy target cells in allogeneic and xenogeneic systems.

Animals↗
PubMed1978

Killing of untreated target cells by nonimmunized rat macrophages in vitro. II. Ultrastructural studies on the interaction of macrophages and rat liver cells.

The sequence of morphological changes following the interactions between macrophages of nonimmunized rats and allogeneic liver cells in vitro were examined by scanning and transmission electron microscopy. The effector cells could be identified as macrophages because of their morphologic characteristics and their ability of latex beads incorporation. The cytotoxic reactions required close contracts between the reactive cells. Effector membrane processes and microvilli attached the target cell surface. Broad contacts and, more frequent, point contacts were observed. After 4 to 5 hrs of incubation the target cells showed pinocytotic activities in the contact regions. Later on submembraneous cytoplasmatic leaks or defects indicated the increasing damage of the target cells. Finally, liver cell ghosts with degenerated organelles were found as morphologic expression of general target cell destruction whereas effector macrophages did not show any damage during the cytotoxic reaction.

Animals↗
PubMed1978

In vitro characteristics of two established hepatoma cell lines.

The in vitro behaviours of a fibroblast-like (DENA-RH 13) and an epithelial-like (DENA-RH 13A) cell line, derived from a chemically induced hepatocarcinoma of rat are described. The DENA-RH 13A can be maintained and studied either in monolayer as a transplantable solid tumor or in fluid-suspension culture as ascites tumor in Wistar rats. The cytomorphology and growth pattern of the clones of the cell lines are described. While DENA-RH 13 cells produced undifferentiated tumors with mainly sarcoma-like structures in allogeneic hosts the epithelial-like cell line (DENA-RH 13A) grew in a carcinoma-like pattern in animals.

Animals↗
PubMed1978

No neoplastic alteration of metabolically competent rat liver cells in vitro by chemical carcinogens: 3-methylcholanthrene, dimethylnitrosamine and Natulan.

Epithelial rat liver cell line RL-19 was checked for aryl hydrocarbon hydroxylase and dimethylnitrosamine demethylase activity. Aryl hydrocarbon hydroxylase activity was found at the rate of about 14.5 pmoles 3-hydroxy-benzopyrene per min per mg protein. This activity was not inducible by 3-methylcholanthrene or by phenobarbital and was independent of the subculture level. From the 45th up to the 59th subculture the mean demethylase activity was about 1.08 nmoles HCHO per min per mg protein, but was decreased to 0.64 nmoles HCHO per min per mg protein at the 131st subculture. RL-19 cells were treated with 3-methylcholanthrene (0.5-1.0 microgram/ml), dimethylnitrosamine (100-400 micrograms/ml), or Natulan (50 micrograms/ml), respectively, for 7 to 10 days. During a 6 months subsequent cultivation no neoplastic changes were observed as revealed by morphological investigation, soft agar assay, and transplantation. It is suggested that metabolic competence for carcinogen activation is only one prerequisite for neoplastic alteration in vitro, and that RL-19 cells are refractory to the action of carcinogens in spite of their metabolic capacity.

Animals↗
PubMed1977

Acid mucopolysaccharides in fibroblast cultures. 4. 35S-sulfate incorporation in dependence on pH-value cell density and lactate.

UNLABELLED: Cultures of embryonic rat fibroblasts were incubated with 35S-sulfate at pH 6.6 and 7.4 (Eagle medium, Hepes buffer) for 48 hours. The MPS were isolated and fractionated. Determination of hexuronic acid was done according to BITTER and MUIR, measuring of sulfate incorporation by liquid scintillation counting. RESULTS: 1. HS, Ch-6-S and DS showed different synthesis rates. They rised at increasing cell density and were lower at pH 6.6 than at 7.4. 2. At pH 6.6 the sulfate incorporation rates (de novo-synthesis) of HS, Ch-6-S and DS are lowered. The percent increase of the MPS fractions at pH 6.6 and their specific activities are explained by individual differences in the unlabelled MPS pools as well as by differences in the rates of synthesis and catabolism. The cell density also has an influence on that. Increase of the MPS at pH 6.6 is by mainly due to an inhibition of catabolism. 3. Contrary to CH-6-S and DS heparan sulfate is catabolized more slowly at high cell densities. 4. The volume of the unlabelled MPS pool is modified by lactate at pH 6.6, e.g. it effectuates enhancement of the DS pool at low cell densities. De novo-synthesis and specific activity are scarcely influenced. CH-6-S and DS catabolism are considerably inhibited, their total amount is increased. The relative synthesis rate of DS is enhanced by lactate. 5. The possible importance of the results for inflammatory processes and wound healing is mentioned.

Animals↗
PubMed1976

[Comparative studies on the cytotoxic effect of composite filling materials and silicate cement].

The biologic compatibility of two composite materials (Cosmic, Epstic) based on Bowen's resin and two silicate cements (Frontasil, Silicap) and theirs components were assessed in cell culture. The compounds eluated from the material specimens under physiological conditions affected monolayer cultures of rat fibroblasts and rat epithelial cells (linr RL-19). Silicate cement eluate brings about death of cells due to high concentration of H-ions. Neutralized eluate of freshly prepared Cosmic, Estic and Frontasil caused the same cell damage which was less pronounced following Silicap eluate. The toxicity was markedly reduced following use of an eluate material which had a setting time of 24 hours. After the 2nd and 3rd elution of same specimen the cytoxicity was noticeably weakened, however, it was still demonstrable. The patterns of injury were different following composite material and silicate cement. All tested components soluted in Eagle medium have an irritating effect on the cultivated cells.

Animals↗