PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Small cell transformation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1976

Ultrastructure of cells infiltrating human kidney allografts.

Cell infiltration is commonly observed in human renal allograft biopsies. This infiltration was investigated using electron microscopy for a more precise assessment of the nature of these cells. More than 3000 cells infiltrating twenty-five renal allograft biopsies were studied. Six cellular types were distinguished and a mean percentage of each type was calculated. Only one-half of these cells were normal or transformed lymphocytes (including small lymphocytes: 22-3 +/- 3-8%, 'intermediary' cells: 22 +/- 3-6%, blast-like cells similar to MLC transformed lymphocytes: 8-1 +/- 2-4%. A relatively high number of plasmocytes (12-4 +/- 2-5%) and a still higher percentage of macrophages (28-5 +/- 4-6%) were found. Granulocytes represented only 2 +/- 0-8%of the cell population. Variations of the mean percentage of these cellular types were studied in various clinical situations.

Cell Movement↗
PubMed1978

Glucocorticoids induce focus formation and increase sarcoma viral expression in a mink cell line that contains a murine sarcoma viral genome.

Dexamethasone (3 X 10(-10) to 3 X 10(-6) M) induced foci of morphologically transformed cells in a small proportion of a mink cell line that contains the Moloney murine sarcoma viral genome (S+L-). The induction was glucocorticoid specific, since other steroids with glucocorticoid activity (prednisolone, cortisol, and aldosterone) induced foci with an efficiency that paralleled their glucocorticoid activity, and steroids lacking glucocorticoid activity (17B-estradiol, testosterone, and progesterone) failed to induce foci. Viral antigen, as measured by specific immunofluorescence, was localized to the foci. The induction of foci by dexamethasone (3 X 10(-7)) was accompanied by an approximately 10-fold increase in intracellular Moloney murine sarcoma virus-specific RNA and viral p30 antigen. Removal of dexamethasone was followed by the disappearance of foci and a decrease in viral RNA and p30. In this cell system, therefore, glucocorticoids can affect the intracellular levels of type C viral RNA and protein.

Animals↗
PubMed1979

[Dynamics of the spreading of normal and transformed hamster cells].

Morphological peculiarities of spreading studied by scanning electron microscopy in two lines of transformed hamster fibroblasts (HETR and HEC--40) were compared to the normal hamster embryo fibroblasts (NHG). The surface of spherical not streading cells was of a mixed type microrelief (small blebs and microvilli). In transformed cells, the microvillous component was more developed than in their normal counterparts. During cell spreading distinct differences were observed between normal and transformed cells in their cell surface contact interaction with solid substratum. NHF cells formed a well-developed concentrically disposed thin lamelloplasm, while HEC-40 cells had asimmetrically disposed lamelloplasm in combination with long filopodia and HETR cells had a rather thick lamelloplasm consisting of several fragments (often forming star-like pattern). At the polarization stage of spreading neither HETR nor HEC-40 reached the same degree of spreading and flattening as NHF. Moreover, the dorsal surface of transformed cells had a complex microrelief in contrast to a rather smooth surface of NHF. These results are discussed in connection with earlier results on spreading of normal and transformed mouse fibroblasts.

Animals↗
PubMed1977

Synthesis, secretion, and attachment of LETS glycoprotein in normal and transformed cells.

LETS glycoprotein is a surface glycoprotein which is absent or greatly diminished on the surfaces of transformed cells. Normal cells secrete large amounts of this protein into the medium; transformed cell medium contains much less. The difference is not due to degradation of the soluble LETS protein. Biosynthesis of LETS protein can be studied by analysis of cell extracts by detergent extraction and immune precipitation and appears to proceed in transformed cells at a reduced rate compared with normal cells. Addition of inhibitors of protein synthesis to transformed cell cultures causes the small amount of LETS protein in the medium to attach to the cells. Addition of normal conditioned medium, which contains LETS protein, to transformed cells alters their morphology towards normal. Addition of purified LETS protein to transformed cells causes the cells to attach, spread, align with one another, and regain actin cables. The results indicate that LETS protein can exchange between cell surface and medium and that it affects cellular adhesion, morphology, and cytoskeleton.

Adhesiveness↗
PubMed1978

Mutants of SV40 with an altered small t protein are reduced in their ability to transform cells.

Mutants of SV40 with deletions of various sizes mapping between 0.54 and 0.59 on the genome grow at a rate equal to or slightly slower than that of wild-type virus, in a range of host cells. Their ability, however, to induce transformation in several mouse, rat and rabbit cell lines is impaired. The extent of transformation observed is dependent upon the assay used to measure it, but in general, the ability of the mutants to transform falls as the size of the deletion increases. In addition, rat embryo fibroblasts transformed by deletion mutants have fewer of the characteristics of a fully transformed phenotype (for example, growth in low serum, increased saturation density, growth in semi-solid medium) than those transformed by wild-type virus. During lytic infection, immunoprecipitable T antigen produced by the deletion mutants is of the same size as that seen during infection with wild-type virus, and is present at a similar level. Mutant virus-coded small t protein, however, is reduced in size compared with that from wild-type virus. For each mutant, the reduction in protein size is dependent upon the amount of DNA deleted, but not on the relative position of the deletion in the genome. These results demonstrate that the DNA sequences mapping between 0.54 and 0.59 on the viral genome code for the small t protein, and that SV40-induced transformation is at least partially dependent upon the expression of this protein.

Antigens, Viral↗
PubMed1977

Characterization of a carcinogen-induced murine B lymphocyte cell line of C3H/eB origin.

A carcinogen-induced lymphoid tumor, denoted 38C-13, obtained in a T cell-depleted mouse of C3H/eB strain, was adapted to continuous culture in vitro and characterized with respect to its cell surface components. The cells possess IgM class immunoglobulins on their surface but do not secrete it. This membrane IgM is composed of mu and L-chains that are similar in apparent molecular weight to those of an IgM myeloma protein. It is also homogeneous as revealed by isoelectric focusing. The cells possess Fc receptors but lack complement receptors as well as Thy-1 and Ia alloantigens. These characteristics indicate that 38C-13 cells are transformed counterparts of small B lymphocytes at an early stage of differentiation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Persistent BK papovavirus infection of transformed human fetal brain cells. I. Episomal viral DNA in cloned lines deficient in T-antigen expression.

After infection of permissive human fetal brain cells by BK human papovavirus (BKV), the vast majority of the cells were killed by the virus, but rare survivors were recovered after frequent medium changes. These surviving cells grew and formed visible colonies after 5 to 6 weeks and were thereafter established as permanent cell lines. These cells, designated as BK-HFB cells, were persistently infected and shed BKV. Morphologically, they were small polygonal cells and had transformed growth properties. Their plating efficiency on solid substrates or in semisolid medium was high, and they were tumorigenic in athymic nude mice. Cloning experiments in medium containing BKV antiserum revealed that BKV did not persist in the cultures in a simple carrier state. All cloned cell lines were initially T-antigen negative and virus-free. However, every clone began to release BKV and again became persistently infected within 3 weeks after removal of BKV antiserum. After rigorous antibody treatment, four of seven clones still released virus spontaneously upon removal of antiserum; three clones have remained virus-free and are apparently cured. Although these cloned cell lines are T- and V-antigen negative when grown in antiserum-containing medium, they retain "free" or episomal BKV genomes; integrated viral DNA was not detected in any of the clones. These free genomes are indistinguishable from prototype BKV DNA and are found in much larger amounts in virus-shedding cell lines.

Antigens, Neoplasm↗
PubMed1978

[Mutagenic and teratogenic effects of cigarette smoke. A summary of experimental and clinical observations (author's transl)].

The mutagenic effect of compounds in cigarette smoke condensate has been demonstrated by the Ames test. A small percentage of cells is transformed into malignant cells. In animal experiments, evidence was found for the teratogenic effects of the contents of cigarette smoke. Among the published epidemiological statistical observations on the effects on humans are a reduction of the birth weight due to maternal smoking, an increase in perinatal mortality if the father smokes and twice the incidence of deformities in children of fathers who smoke heavily. The knowledge of these connections should be of significance for family planning consultation.

Birth Weight↗
PubMed1976

Simian virus 40-chinese hamster kidney cell interaction. II. The semipermissivity of the cell system.

Throughout in vitro passages, Chinese hamster kidney (CHK) cells progressively lost susceptibility to SV 40 virus infection while remaining continuously susceptible to viral DNA infection. Upon infection with SV 40 virus or viral DNA, the CHK cell line supported viral DNA and virus replication at a low level. SV 40 transformed CHK cell lines spontaneously produced small amounts of viral DNA and virions. The percentage of virus-producing cells was low. Various clones derived from each of these lines behaved as the parental cell population, leading to the conclusion that each CHK cell, whether transformed or not with SV 40, is potentially permissive for this virus.

Animals↗
PubMed1978

[Crystallization and dissolution of collagen fibrils during the histogenesis of the intervertebral disk].

We studied the modifications of collagen fibrils during the histogenesis of the intervertebral disc of cats. In connexion with these studies it is necessary to distinguish between the fibrillar (functional) structure, the arrangement of fibrils, and the nature of fibrils, their diameter, period and other properties. Collagen fibrils (40--50 nm) of the anulus fibrosus enter in hyaline cartilage and split off in thin fibrils (8--10 nm). In this area the cartilage fibrils have a diameter of 20--22 nm, in a greater distance the diameter is diminished to 7--8 nm. Analogous to the changing of the nature of fibrils, the number of the cells related to the sectional area is diminished. The cells of the anulus fibrosus resemble those of tendons. In the transition area their shape becomes roundish, the number of granular membranes is increased, a voluminous Golgi-Apparatus appears for a short time. Finally, the cells are once transformed in cartilage cells with a small reticulum or cells of fibrocartilage with a capsule and a decreased cytoplasm; some cells are disintegrated. In the capsule of the fibrocartilage cells, parallel orientated filaments exhibit a periodical arrangement. In the border of the capsule, filaments change into periodical fibrils. Therefore, we must regard cells and their surrounding intercellular substance as metabolic unity which in the cartilage may be characterized as the chondron.

Animals↗
PubMed1978

The effect of extraction of the intrafascicular contents of peripheral nerve trunks on perineurial structure.

The intrafascicular contents have been extracted from the tibial nerve of the rabbit through perineurial incisions. Within 6--8 days following this procedure, the perineurial cells separate from one another, become dissociated from their basement membranes and assume a fibroblast-like appearance. The intrafascicular space becomes populated with endoneurial fibroblasts. With the ingrowth of regenerating axons, bundles of axons and associated Schwann cells become surrounded by cells of fibroblastic appearance which undergo perineurial transformation resulting in the development of multiple small fascicles. The cells of the surrounding perineurium appear to reassume a lamellar organization and to reestablish contacts with each other with the formation of junctional complexes. It is therefore suggested that neural structures may be responsible for the development and maintenance of the structural organization of the perineurium.

Animals↗
PubMed1978

Small cell carcinoma of the lung: cellular origin and relationship to other neoplasms.

Many small cell carcinomas share morphological and physiological characteristics with normal and neoplastic cells of Pearse's APUD series, including pulmonary APUD cells and pulmonary carcinoid tumors. There is very likely more than one type of APUD cell in the lung, and conclusions that small cell carcinomas and carcinoids reflect neoplastic transformation of the same cell type are probably premature. The embryoogic lineage of pulmonary APUD cells is at present uncertain. The hypothesis that all APUD cells are derived from the neural crest is no longer tenable, and although some evidence does suggest a neural contribution to the pulmonary epithelium, additional embryologic studies are required. Some tumors that currently are classified as small cell carcinomas probably do not have APUD cell characteristics, and still others appear to have both APUD and non-APUD features. A subclassification of small cell carcinomas based on a combination of physiological and morphological features might prove to be of prognostic and therapeutic value, but current knowledge probably would not provide a sufficient foundation for a reliable or practical subclassification. Multidisciplinary studies of the differentiation and function of normal and neoplastic APUD cells in the lungs and elsewhere are needed.

APUD Cells↗
PubMed1979

Hodgkin's disease with lymphocytic predominance, nodular type (nodular paragranuloma) and progressively transformed germinal centres--a cytohistological study.

The histology, cytology, and enzyme cytochemistry of a nodular variant of Hodgkin's disease with lymphocytic predominance, called 'nodular paragranuloma', are presented. The histological features of nodular paragranuloma are compared with those of progressively transformed germinal centres, which are enlarged follicles showing a predominance of small lymphocytes and some residual germinal centre cells. Progressively transformed germinal centres are sometimes found in nonspecific lymphadenitis (reactive hyperplasia). The histological similarity and the association between lymph nodes with nodular paragranuloma and lymph nodes with progressively transformed germinal centres in the same patient at different moments or at the same time, suggest that progressively transformed germinal centres are the origin of nodular paragranuloma. Hence, it must be concluded that nodular paragranuloma takes place in B-cell areas of the lymph node, unlike the other, or at least most of the other, types of Hodgkin's disease.

Adult↗
PubMed1977

[Morphological, cytochemical autoradiographic and quantitative studies of the cells in lymphocyte cultures with added tuberculin].

Lymphocyte culture experiments with purified tuberculin showed a transformation of small lymphocytes into medium sized, large and very large basophilic cells. During cell growth RNA synthesis and acid phosphatase activity increased. Some of the very large basophilic cells synthesized DNA. During the first and second day of culture experiment also medium sized and large weakly basophilic cells increased, which have a pale plasma and azurophilic granules. These cells did not synthesize DNA and showed only a low incorporation of 3H-uridine. The results of our experiments indicate a transformation of medium sized and large basophilic cells not synthesizing DNA into weakly basophilic (pale) cells showing azurophilic granules. In contrast to the lymphocyte culture experiments with tuberculin lymphocyte cultures without tuberculin showed no significant increase of medium sized, large and very large basophilic cells and of weakly basophilic cells.

Acid Phosphatase↗
PubMed1978

Codistribution of pericellular matrix proteins in cultured fibroblasts and loss in transformation: fibronectin and procollagen.

Antibodies to fibronectin and to distinct types of procollagens and collagens were used in immunofluorescent staining to localize these proteins in cell cultures. Normal human skin or lung fibroblasts produced a fibrillar pericellular matrix in which fibronectin and procollagen (types I and III) showed extensive codistribution. Fibronectin and procollagen were synthesized by the same cells as judged by double-stain immunofluorescence. Pericellular procollagen was specifically digested with collagenase without an effect on the fibrillar distribution of matrix fibronectin. Brief treatment with trypsin removed both matrix proteins. The human tumor cell lines HT-1080 (fibrosarcoma) and RD (rhabdomyosarcoma) produced little or no matrix fibronectin or procollagen. At sites of cell contact, simian virus 40-transformed lung fibroblasts (VA13) produced small amounts of pericellular fibrillar matrix fibronectin that codistributed with procollagen type I. Intracellular fibronectin and procollagen were visualized in all of these human sarcoma cell lines. When chicken embryo fibroblasts infected with a T class mutant (NY68) of Rous sarcoma virus temperature-sensitive for transformation were maintained at the nonpermissive temperature (41 degrees ) the cells had normal phenotype and a fibrillar matrix containing fibronectin and procollagen was present. At the permissive temperature (35 degrees ), the cells showed transformed phenotype and the matrix was lost. The failure to produce a pericellular fibronectin/collagen matrix may account for several phenotypic characteristics of transformed cultured fibroblasts.

Cell Line↗