[Occurrence of viral particles of avian sarcoma viruses in sarcoma tissue]. / Výskyt vírusových castíc vtácieho sarkómového vírusu v sarkómovom tkanive.

An electron-microscopic examination was performed of chicken fibrosarcoma caused by avian sarcoma virus (ASV), strain B 77, to investigate virus budding and release through the cytoplasmic membrane. The virus particles of type C- were 90-100 nm in size, the electron-optically denser nucleoids being clearly differentiated from the outer membrane.

[Brain tumor induced in dogs by intracerebral inoculation of SR-RSV induced cultured tumor cells--electron microscopic study].

An experimental transplantable canine brain tumor model with the advantages of rapid tumor growth within 10 days and relative safety for the investigator is presently available. The tumor is produced by intracerebral inoculation of cultured cells derived from a canine brain tumor induced by the Schmidt-Ruppin strain of the Rous-Sarcoma virus (SR-RSV). It has potential use as a model in experiments designed to evaluate the effectiveness of chemotherapy and radiotherapy with serial computerized tomography scans. However, characterization of the induced tumor is essential. Ideally, it should have features attributable to glioma and/or neuroectodermal tumors. Utilizing the technique of intracerebral inoculation of cells cultured from the original dog brain tumor induced by SR-RSV, Salcman et al identified the tumor they induced in brains of mongrel puppies as a glioma by light microscopic criteria (Reference). The purpose of our study was to further characterize this experimental tumor by electron microscopic and immunohistochemical techniques. Tumor was induced in 6 mongrel puppies. Stains of the tumor for immunohistochemical reactivity to glial fibrillary acid protein, S-100 protein and 210K neurofilament protein were all negative. With the electron microscope, the intracerebral tumor cells were mostly undifferentiated. They had a few cell processes, occasional punctate adhesions and some microvilli-like structure. The tumor cell nucleus was usually oval shaped and sometimes had nuclear indentations. The cytoplasm contained abundant free ribosomes, some rough endoplasmic reticulum and mitochondria. Collagen fibers and basal lamina were not observed in the intercellular spaces. The capillaries within the tumor were characterized by proliferation of immature endothelial cells which were non-fenestrated.(ABSTRACT TRUNCATED AT 250 WORDS)

An attempt at comparison of the morphology of normal and RSV--transformed cells in a scanning microscope.

The electronic scanning microscope (SEM) was first used to analyze biological material in 1965 (Hollenberg M. et al. The Journal of Histochem. and Cytochem. 21, 109-130, 1973). It has since been possible to collect specific data on cell morphology and the changes in cell surface and structure caused by external factors, such as oncogenic viruses.

Loss of proviral sequences in RSV-transformed mouse tumour cells accompanied by the formation of double-minute chromatin bodies.

The RVA2 cell line, derived originally from a tumour induced by the Schmidt-Ruppin strain of RSV and passaged repeatedly in vivo and in vitro, was studied. This cell line was originally virogenic and the virus was rescuable with high efficiency from it. When rechecked after prolonged passage history, the efficiency of virus rescue was found to drop to very low levels and from one monocellular clone derived from such cell population no virus was rescued at all. After further 14 in vivo passages of RVA2 cells, no transforming virus rescue was obtained, even in the presence of a helper virus. Nor were the U5 sequences of LTR found in these cells. Karyologic analysis revealed the presence of double-minute chromatin bodies in the RVA2 cell population studied. The frequency of mitoses containing DMs doubled after 14 in vivo passages. The possibility is discussed that DMs as the site of gene amplification also contain amplified cellular oncogenes which might take over direction of the malignant state of the cell in which the original transforming viral gene (v-src) is no longer active or is lost.

[Cell membrane characteristics and biological behavior of virus transformed cells (author's transl)]. / Zellmembranveränderungen und biologisches Verhalten von Virus-transformierten Zellen.

The transformation of a normal into a tumor cell is not caused by a single molecular event, but is the consequence of several simultaneous or consecutive molecular processes, which lead to a variety of changes in the structure and the metabolism of the cell. Investigations with the Rous sarcoma virus show that a single gene is primarily responsible for these changes that is coding for a phosphoprotein which, however, is multifunctional. The biochemical and biologic events which initiate and maintain the transformed status of the cell involve mainly the cytoplasma membrane. At both the outer and the inner surface of the cell membrane dramatic changes occur which influence the cell structure, permeability of the cytoplasma membrane, and the intracellular metabolic pathways. Most probably, these transformation-associated events are also involved in cell proliferation under physiologic conditions. In the tumor cell, however, they are not further regulated physiologically, with the consequence of an uncontrolled and incessant cell division.

Behaviour of normal and neoplastic rat cells on grooved substrates.

The distribution and shape of rat cells cultivated on plastic surfaces containing cylindrical areas of various radii and grooves of various depths were studied. Normal embryo cells and two lines of neoplastic cells (LW13K2 and RsK4) were used. The nuclear shape, orientation of the nuclei and migration of cells from the bottom of the grooves were assessed by quantitative methods. All characteristics of the behaviour of both neoplastic cell lines on the grooved substrates were found to be different from those of normal cells: a) the nuclei of neoplastic cells, in contrast to those of the normal ones, did not undergo additional elongation on the cylindrical areas of the substrate; b) the orientation of neoplastic cells with regard to the axis of the cylindrical substrate was decreased or absent; c) the migration of neoplastic cells from certain types of the grooves was decreased. It is suggested that the different reaction to the geometry of the substrate may be a characteristic feature of transformed cells. Possible mechanisms of these alterations are discussed.

[Marker chromosomes of murine cell lines]. / Markernye khromosomy nekotorykh linii myshinykh kletok.

Using the C-method of chromosome staining four marker chromosomes were revealed in the transplanted murine line SC-1, one comparatively rare marker chromosome was shown in RAG line, small marker chromosomes occurred almost in all cells of RVP3 line. Marker chromosomes found in the studied lines by the C-method of chromosome staining make it possible to distinguish these lines from each other.

[Immunological and structural properties of Rous sarcoma virus-transformed and tumor cells]. / Propriétés immunologiques et structurales des cellules transformées et tumorales induites par le virus du sarcome de Rous.

We compared the capacity of both normal and Rous sarcoma virus (RSV)-transformed chicken embryo fibroblast (CEF) cells as well as Rous sarcoma (RS) tumor cells to serve as targets in anti-tumor immunity assays. These studies showed that sera from tumor-bearing donors were able to stain transformed CEF more efficiently than RS cells as detected by immunofluorescence. In contrast, antiserum against the major viral glycoprotein, gp 85, stained a higher percentage of RS than transformed cells. Normal CEF cells, which served as controls, were essentially non-reactive with the immune system as judged by this type of assay. We observed that RS cells are considerably larger and contain far higher levels of protein than either normal or transformed CEF. Scanning electron microscopy revealed both the RS cells and transformed CEF to be rich in surface ruffles, blebs and microvilli as distinguished from the flattened, fusiform appearance of normal CEF cells.

[Transplantable experimental tumor. Morphological and ultrastructural study (author's transl]. / Tumore sperimentale trapiantabile. Studio morfologico ed ultrastrutturale.

An experimental tumor which has been induced in newborn chicken, was transplanted into inbred BALB/c mice and then studied by the means of light and electron microscopy. Sendai virus fusion between MSV-H transformed rat cells and chickembryo cells provided the tumor. Histological pattern of this neoplasia seems to be superposable, both in chicken and in mouse, to that of anaplastic fibrosarcomas and shows some differences from either Rous sarcoma or BALB/c mouse H-6668 spontaneous rabdomyosarcoma patterns. tumor malignancy was evaluated onthe basis of rapid growth

Differentiation of progressive versus regressive Rous virus-induced avian sarcomas according to tumor and infiltrating lymphocyte fine structure.

Electron microscope examination of progressing and regressing Rous virus-induced sarcomas in an inbred line of White Leghorns revealed that regressing tumors contained moderate to marked lymphocyte infiltration, frequent contact between lymphocytes and tumor cells, and extensive areas of necrosis. Lymphocytes infiltrating regressing tumors exhibited a polar accumulation of organelles at the point of contact between lymphocyte and target cell. On the other hand, progressing tumors contained low to moderate numbers of lymphocytes, infrequent lymphocyte-tumor cell interaction and less evidence of tumor cell degeneration. Lymphocytes from progressing tumors lacked the polar organization of organelles. This experimental system is offered as a means of studying the role of lymphocytes in tumor regression.

Long-term karyological study of RVP3 tumour cells grown in vitro.

The RVP3 cell line established from an in vivo passaged RVP3 tumour, which originally arose in RSV-injected mice, was analyzed at different passage levels and characterized virologically and cytogenetically. The RVP3 cell line is characterized by the presence of 2 to 5 medium-sized to large metacentric chromosomes, the majority of the mitoses contain about 1 subtelocentric chromosome, and in addition, every mitosis contains several chromosomal structures corresponding to the group called m-ms that comprises both minute chromatin bodies and microchromosomes. In three monocellular clones derived from the RVP3 cell line with a similar karyological picture it was established that the number of m-ms increased proportionally to the total number of chromosomes in individual metaphases. It was verified that: the RVP3 cell population does not contain any transmissible agent producing chromosomal changes in mouse cells; RVP3 cells are highly malignant; no RSV could be rescued from the clone tested. The significance of m-ms is discussed.