| identification of the virions in the in vitro l1210(v) leukemia cell lines by morphological, virological, and immunological techniques. | in vitro l1210 (v) cell lines contained abundant intracytoplasmic a-particles, numerous c-type particles, a small number of b-type particles, and occasional intracisternal a-particles. the intracytoplasmic a-particles were incorporated into both spiked (b-type) and smooth-surfaced (c-type) particles formed at the budding site. both b-and c-type particles also developed by gradual accululation of neucleooid material. the particles, particularly the c-type, exhibited a wide range of densities. the ... | 1975 | 163689 |
| hapten-sandwich labeling. ii. immunospecific attachment of cell surface markers suitable for scanning electron microscopy. | a hapten-sandwich procedure has been used for immunospecific labeling of cell surface antigens with markers visible by scanning electron microscopy. antihapten antibody was used to link hapten-modified tobacco mosaic virus, bushy stunt virus, or hemocyanin to hapten-modified human erythrocytes. the antihapten antibody bridge was also used to link the hapten-virus marker to hapten-modified antibodies against mammary tumor virus on mouse mammary tumor cells, or against immunoglobulin receptors on ... | 1975 | 163829 |
| distribution of murine type b and type c viral nucleic acid sequences in template active and template inactive chromatin. | template active chromatin and template inactive chromatin have been fractionated from mouse cells infected with the moloney strain of murine leukemia virus. in vivo the cells produce abundant rna homologous to moloney leukemia virus, but do not produce either globin mrna or rna homologous to type b mouse mammary tumor virus. the dna extracted from the template active chromatin or template inactive chromatin contained equal amounts of sequences homologous to moloney type c virus, to type b virus, ... | 1975 | 164292 |
| glucocorticoid-receptor interaction and induction of murine mammary tumor virus. | the relationship between the cellular uptake of glucocorticoid hormones, the binding of these hormones to specific in vitro receptors, and the induction of mouse mammary tumor viruses in an established mouse mammary tumor cell line was highly correlated. these results suggest that the induction of mouse mammary tumor virus by glucocorticoid hormones is a physiological process acting through a mechanism of high affinity, saturable steroid-receptors. a temperature-sensitive or salt-dependent step ... | 1975 | 164467 |
| mammary tumor virus particles in the submaxillary gland, seminal vesicle, and nonmammary tumors of wild mice. | type-b mammary tumor virus particles were detected by electron microscopy in the submaxillary glands of 6 of 27 freshly trapped, pregnant wild mice (mus musculus). type-b particles were also detected in 3 9f 24 seminal vesicles and 2 pulmonary adenomas from wild mice. intracytoplasmic type-a virus particles were found in 7 spontaneous nonmammary tumors (lymphoma, hepatoma, lung adenoma) of aging wild mice. type-c virus particles were also detected in many of these tissues. | 1975 | 165306 |
| long-term primary culture of mouse mammary tumor cells: production of virus. | long-term primary cultures of mouse mammary tumor cells proved an excellent source of mouse mammary tumor virus (mmtv). virus purified from these primary cultures had the same morphologic biochemical, immunologic, and biologic characteristics as mmtv. quantitation of mmtv-protein equivalents released into the medium was measured by the radioimmunoassay for mmtv. peak production levels were 20-40 mug mmtv protien equivalents/75-cm-2 flask/24 hours. these cultures produced mmtv for as long as 90 ... | 1975 | 165313 |
| affinity chromatography of viral dna polymerases on pyran-sepharose. | pyran covalently linked to cyanogen bromide-activated sepharose has been shown to be an effective affinity matrix for several viral dna polymerases. differential salt elution of viral compared with cellular polymerases, as well as substrate elution, suggests the affinity nature for the matrix. unlike some other affinity systems described, pyran-sepharose is totally resistant to nuclease digestion and is stable at 4 degrees for several months. dna polymerases isolated from several viruses by dete ... | 1975 | 165485 |
| endogenous oncornaviruses in chemically induced transformation. i. transformation independent of virus production. | | 1975 | 165619 |
| virion-associated and cellular rna methylase activity in normal and neoplastic mammary tissue from mammary tumor virus-infected and -uninfected mice. | a comparison of cellular rna methylase activities and patterns between normal and neoplastic mouse mammary tissue indicated the following. the rna methylases of mammary tumor tissue extracts are qualitatively different from those of normal lactating mammary tissue, based on differences in extent of methylation; the normal lactating tissue extracts have a greater capacity of methylate rna than do the tumor extracts studied to date. there is no correlation between capacity and either the malignant ... | 1975 | 165888 |
| lipid and protein composition of the mammary tumour virus and the milk fat-globule membrane isolated from the milk of infected mice. | | 1975 | 165994 |
| immunologic, virologic, and genetic aspects of mammary tumor virus-induced cell-surface antigens: presence of these antigens and the thy 1.2 antigen on murine mammary gland and tumor cells. | the distribution of the normal differentiation antigen thy 1 and the mammary tumor virus (mtv)-induced antigens or antigen complexes mlm and mlr were studied in mouse mammary gland cells, mammary tumor cells, and other cell types, by use of ascites leukemia cells of the gr mouse strain as target cells in the cytotoxicity test. the thy 1.2 antigen was detected by an akr antiserum to c3hf thymocytes. mlm was shown by a homologous c57bl antiserum to grsl2 leukemia (absorbed in vivo in gr mice); mlr ... | 1975 | 166186 |
| distribution and antibody-induced redistribution of a mammary tumor virus-induced and a normal antigen on the surface of mouse leukemia cells. | by means of the indirect membrane immunofluorescence test, the distribution and antibody-induced redistribution (patching and capping) of a mammary tumor virus-induced (mlr) and a normal (thy 1.2) cell-surface antigen were compared on mouse thymocytes and leukemia cells (grsl2). at 0 degrees c thy 1.2 fluorescence was ringlike and more intense on grsl2 cells than on thymocytes, whereas mlr fluorescence on grls2 cells at this temperature was patchlike and brighter than thy 1.2 fluorescence. at 20 ... | 1975 | 166187 |
| newer knowledge in comparative virology--its contribution to human health research. | like other comparative sciences, and despite its recent beginning comparative virology has already contributed useful applications and observations to human health research. teachings derived from the study of marek's disease found application in that of burkitt's lymphoma, and may lead to a possible vaccine against the human disease. equally useful information came from the study of canine distemper in the development of a chorio-allantoic membrane attenuated measles vaccine, and in our knowled ... | 1975 | 167504 |
| non-t cell killing of mammary tumor cells by spleen cells: secretion of antibody and recruitment of cells. | both t cell-mediated killing and non-t cell-mediated killing of target mtv-induced mammary tumor cells can be detected in microcytotoxicity assay tests of spleen cells from mice immunologically responsive to either the histocompatibility antigens or the virus-associated antigens of the target cells. the non-t cell-mediated cytotoxicity is antibody-dependent; otherwise inactive cells (null cells) can be recruited to activity by target cell-specific factors obtained from the supernatant of short-t ... | 1975 | 168254 |
| expression of mouse mammary tumor viral polypeptides in milks and tissues. | a 14,000-dalton polypeptide (p14) from riii murine mammary tumor virus (mmtv) has been isolated by column chromatography in 6 m guhcl. antiserum prepared in rabbits specifically precipitated 125i-labeled p14; in double antibody competition, radioimmunoassays performed with limiting amounts of antibody, both purified p14 and disrupted mmtv, competed specifically with labeled antigen. the expression of this mmtv type b virus antigen could be measured by competition radioimmunoassays in milks, mamm ... | 1975 | 168263 |
| intracellular synthesis of mouse mammary tumor virus polypeptides: indication of a precursor glycoprotein. | mouse mammary tumor virus polypeptides were detected in the cytoplasm of mouse mammary tumor cell cultures using immunological precipitation techniques. the anti-mouse mammary tumor virus serum precipitated the major virion glycoproteins gp49 and gp37.5/33.5 and a viral-related nonvirion glycoprotein of 76,000 daltons. subcellular fractionation studies revelaed that the cell-associated virion glycoproteins were present in the membrane fraction. pulsechase experiments indicated that a viral-relat ... | 1975 | 168401 |
| mouse mammary tumors: alteration of incidence as apparent function of stress. | eighty to 100 percent of female mice of the c3h/he strain carrying the bittner oncogenic virus usually develop mammary tumors within 8 to 18 months after birth when studied under the usual housing and experimental conditions. by subjecting various groups of such mice to environmental circumstances providing different degrees of chronic stress, mammary tumor incidence at 400 days was modified, with incidences ranging from 92 percent under stress to 7 percent in a protected environment. the data s ... | 1975 | 168638 |
| correction of a murine mammary tumor virus-associated immunological depression by selective immunosuppression with cytosine arabinoside. | mammary tumor virus (mtv) infection has been shown to be associated with a diminished hypersensitive reaction to methylated bovine serum albumin. since methylated bovine serum albumin-induced hypersensitivity appears to be a mixed [humoral versus cell-mediated immunity (cmi)] reaction, the deficit in reactivity could be caused by, among other things, a direct depression of cmi or an increase in a humoral, blocking component. assay of oxazolone-induced contact sensitivity and phytohemagglutinin-i ... | 1975 | 168963 |
| quantitation of virus-induced (mlr) and normal (thy.1.2) cell surface antigens in isolated plasma membranes and the extracellular ascites fluid of mouse leukemia cells. | plasma membranes were isolated by two methods from mouse leukemia cells containing mammary tumor virus-induced (mlr) and normal (thy.1.2) antigens on their surfaces. a number of chemical components, enzymic activities, and the antigenic contents were determined in subcellular fractions and found to be specifically concentrated in the plasma membrane fractions. the major part of the cellular mlr, in contrast to thy.1.2, was present in the 105,000 x gmax supernatant of the cell homogenate. this an ... | 1975 | 168966 |
| endogenous mammary tumor viruses in mice. | | 1975 | 169016 |
| glucocorticoid induction of murine mammary tumor virus in vitro. | | 1975 | 169017 |
| mouse mammary tumor virus polypeptide precursors in intracytoplasmic a particles. | intracytoplasmic a particles were analyzed by immunodiffusion and sodium dodecyl sulfate--polyacrylamide gel electrophoresis (sds--page) before and after enzymatic cleavage with trypsin. a common antigen in a particles was detected by antisera prepared against purified intracytoplasmic a particles, purified mouse mammary tumor virus (mmtv), and a purified mmtv core polypeptide (p28). despite this correlation, no sds--polyacrylamide band migrating at p28 was observed in purified intracytoplasmic ... | 1975 | 169380 |
| further studies on the radioresistance of highly purified mouse and mammary tumor virus. | | 1975 | 170116 |
| electrophoretic mobilities of rna tumor viruses. studies by doppler-shifted light scattering spectroscopy. | we have used laser beat frequency light scattering spectroscopy to measure, at several ph values, the electrophoretic mobilities of purified avian myeloblastosis (amv), murine leukemia (mulv), murine mammary tumor (mumtv), and feline leukemia (felv) viruses. the mobilities of these viruses are similar at ph greater than or equal to7 (-2.7 to -3.2 x 10(-4) (cm/sec)/(v/cm). the isoelectric points of mulv and amv are apparently less than ph 3, whereas for felv the data could be interpreted to indic ... | 1975 | 170961 |
| serological analysis of an oncornavirus (pmf virus) detected in malignant permanent human cell lines. | immunodiffusion analysis of the pmf virus which was detected in malignant permanent human cell lines revealed positive reactions with antisera against the mason-pfizer monkey virus (mpmv). no cross-reactivity was demonstrated with murine leukemia virus (mulv), rat leukemia virus (ralv), hamster leukemia virus (halv), feline leukemia virus (felv), simian (woolly monkey) sarcoma virus (ssv-1) and mouse mammary tumor virus (mtv). the cross-reactive antigens of the pmf virus and the mpmv are conside ... | 1975 | 171892 |
| fine structure of a murine mammary carcinoma cell line. | a fine structural study was made of cells from the epithelioid mcf-8/5-2a cell line derived from a mumtv-free d2 transplantable hyperplastic outgrowth. electron microscopy shows the cells to be truly epithelial with many cell-to-cell junctions and microvilli. the cells are similar in many respects to normal mouse mammary gland and some of the conventional mammary tumor derived cell lines. this study supports previous observations of the absence of mumtv in mcf-8 within the limits of morphologica ... | 1976 | 172439 |
| studies of genetic transmission of mammary tumour virus by c3hf mice. | by radioimmunoassay (ria) mammary tumour virus (mtv) antigens were detected in individual milk samples of c3hf mice, (female balb/c x male c3hf)f1 mice and (female c3hf x male balb/c)f1 mice; milk samples of balb/c mice were negative. in the segregating backcross i population, female balb/c x male (female balb/c x male c3hf) viral antigens were found in the milk of 93 out of 169 mice (55%). in the bc ii population (daughters of bc i mothers and balb/c fathers) two groups were distinguished. in t ... | 1975 | 172460 |
| [viruses and mammary carcinogenesis]. | bittner virus has been extensively studied by recent electron microscopy and molecular biology techniques. the structure, the biochemical, physical and antigenic properties of the rna tumor viruses - i.e. the mouse mammary tumor virus (mmtv) - are well known. recent observations in human tissues of particles similar to animal viruses that are known to be oncogenic have raised the hypothesis of the role of viruses in human cancer. in mice, breast cancer can be caused by a virus - the bittner viru ... | 1975 | 172551 |
| relationship in nucleic acid sequences between mouse mammary tumor virus variants. | primary cultures of mouse mammary carcinomas were used as a source of both radioactively labeled and unlabeled 60-70s rna of mouse mammary tumor virus (mmtv) obtained from various mouse strains. competition molecular hybridization experiments revealed that, within the limits of the assay, the rnas of the mmtvs synthesized in culture by the tumors of the mouse strains riii, gr, a, and c3h, are identical. a comparison of the genomes of the milk-transmitted mmtv(c3h) and the vertically transmitted ... | 1975 | 172912 |
| mammary tumor virus and host genome in the transmission and causation of mammary tumors in mice. | | 1975 | 173454 |
| response of c3h-avyfb female mice to a low oncogenic, milk-borne mammary tumor virus. | when low oncogenic milk-borne mammary tumor virus (mtv) of strain dd was tested in c3h-avyfb mice, as compared with the similar strain c3hfb, mammary tumors occurred with a higher incidence and at lower age in c3h-avyfbfdd (with dd-mtv) than in c3hfbfdd (with dd-mtv), as observed in virgin females. since the effect of breeding tended to mask any difference between the breeders, mammary tumor incidences were similar with a slightly higher age at tumor occurrence in the c3h-avyfbfdd females. thus ... | 1975 | 173862 |
| identification of a precursor protein to the major glycoproteins of mouse mammary tumor virus. | mouse mammary tumor virus-producing cultures of mouse mammary tumor cells synthesize a viral-related polypeptide of molecular weight of 73,000 (gp 73) which is rapidly labeled during a short pulse but disappears during the chase concomitantly with the appearance of label in the virion glycoproteins gp 49 and gp 37.5/33.5. the addition of the protein synthesis-inhibitor cycloheximide to the chase medium has little effect on this conversion. treatment of the proposed precursor with alpha-chymotryp ... | 1975 | 173889 |
| biochemical and physiological mechanisms in glucocorticoid hormone induction of mouse mammary tumor virus. | | 1976 | 174289 |
| comparative study of the milk fat globule membrane and the mouse mammary tumour virus prepared from the milk of an infected strain of swiss albino mice. | milk fat globule membranes and mammary tumour virus particles (d=1.17 g/cm3) have been obtained from the milk of a swiss albino mice strain. comparative biochemistry shows that these two structures differ significantly in the phospholipid, polypeptide and glycopolypeptide patterns and enzymatic activities. however, the lipid profile and the morphology of both structures suggest a filiation with the plasma membrane. density fractions obtained from the crude virus preparation have been thoroughly ... | 1976 | 174729 |
| macrophage migration inhibition and lymphocyte stimulation with mammary tumor virus associated antigens in balb/c mice. | lymphocytes of mtv-negative balb/c mice are sensitive to one or more antigens of mtv as determined by blastogenic transformation and migration inhibition assays. the lymphocytes from mtv-positive balb/cfc3h mice are nonresponsive in these assays but become responsive after the mice have been implanted with mtv-positive tumors. the latter findings imply that there may be either a state of tolerance to mtv antigens which is broken by the tumor transplant or that the responses are directed towards ... | 1976 | 175373 |
| [transplantable sebaceous adenoma of the mouse with virus particles studied by electron microscopy (author's transl)]. | histology and ultrastructure of a sebaceous adenoma of the mouse -- derived from i.p.-injection of 0.1 ml dna, isolated from cells of a transplantable mouse-leukemia -- were studied. the original tumour and all transplanted tumours display the same tissular differentiation. in all tumours virus particles were found. structure and behaviour of the intracytoplasmic a-particles resemble those of the mouse mammary tumour virus while the c-particles found extracellular were identical with the leukemi ... | 1976 | 175593 |
| unusually high incidence of spontaneous mammary carcinomata in a colony of balb/c mice. | | 1975 | 175817 |
| natural immunity in the oncornavirus-infected mouse. | balb/cfc3h females neonatally infected with mammary tumor virus (mtv) possess spleen cells capable of significant cytotoxic activity against target mtv-induced mammary tumor cells in microcytotoxicity assay. spleen cells from supposedly mtv-free balb/c females are also specifically reactive, as a result of horizontal transmission of mtv antigens. no quantitative differences in reactivity exist between females not susceptible to the development of mammary tumors (balb/c) and those that may develo ... | 1976 | 175933 |
| correlation of in vitro and in vivo studies of antigens relevant to the control of murine breast cancer. | the specific immune response of c3h [mammary tumor virus (mtv)] (mtv+) and c3hf sublines (mtv- or milk-mtv-) to mammary tumors of c3h origin was measured in vitro by the ability of lymphocytes derived from immunized animals to destroy 3h-proline prelabeled target cells after 36 hr of incubation in vitro (lymphocyte:target ratio, 400:1). primary cytotoxic responses were obtained both in c3h and c3hf mice and were mediated mainly by t-lymphocytes (thy.1-positive cells). the degree of cross-reactiv ... | 1976 | 175934 |
| implications of humoral antibody in mice and humans to breast tumor and mouse mammary tumor virus-associated antigens. | as a part of a program directed toward the elucidation of the role of viruses in mouse and human breast cancer, a variety of immunological techniques were applied to a study of the humoral immune response of mice and of humans to their breast tumors. tumor-bearing mice were found to produce antibodies against a complex array of tumor cell-associated antigens, including mouse mammary tumor virus (mmtv), components, heterophile and forssman-like antigens, embryonic antigens, and possibly other tum ... | 1976 | 175935 |
| biological considerations of tumor-specific and virus-associated antigens of human breast cancers. | in vivo and in vitro studies bearing on tumor-specific and viral-associated antigenicity of human breast carcinomas were reviewed with particular attention to the following clinical considerations: (a) breast carcinomas arise in a nonrandom fashion; (b) in situ carcinomas precede invasive breast carcinomas; (c) invasive breast carcinomas behave in a heterogeneous fashion. microscopically demonstrable lymphoreticuloendothelial responses, skin window tests, and leukocyte migration tests all indica ... | 1976 | 175936 |
| specificity of cell-mediated immunity in mouse-human cross-reactions: formal discussion. | | 1976 | 175937 |
| further immunization studies with mammary tumor virus. | a single i.m. dose of formalin-inactivated murine mammary tumor virus greatly reduces viral expression and mammary tumorigenesis in af (tumor incidence, 39%) and riiif (tumor incidence, 11%) mice, which carry only endogenous, gamete-transmitted virus. in c57bl mice, 1 mug of vaccine in freund's complete adjuvant protects against later challenge with riii virus. | 1976 | 175938 |
| immunological control of breast cancer: discussion. | | 1976 | 175939 |
| surface localization of virus production on a glucocorticoid-stimulated oncornavirus-producing mouse mammary tumor cell line by scanning electron microscopy. | a chronically infected continuous mouse mammary tumor cell line containing virus particles of type b morphology, free of contaminating type c virions, has been grown in tissue culture. these cells were treated with dexamethasone, a synthetic glucocorticoid, a potent stimulator of mouse mammary tumor virus expression. surfaces of untreated and dexamethasone-treated cells were investigated by scanning electron microscopy. untreated cells demonstrated a moderate expression of mouse mammary tumor vi ... | 1976 | 175951 |
| humoral host defense mechanisms against tumors. | | 1976 | 176124 |
| antibody in the sera of tumor-bearing mice that mediates spleen cell cytotoxicity toward the autologous tumor. | pretreatment of mtv-induced balb/cfc3h mammary tumor cells with autologous serum results in increased spleen cell cytotoxic activity and the recruitment of previously inactive spleen cells to cytotoxic activity against the target cells. these recruiting antibodies are tumor-specific for individual tumors; pretreatment with such serum of target cells of an mtv-induced mammary tumor obtained from a different balb/cfc3h female results in blocking of spleen cell activity. the autologous recruiting f ... | 1976 | 176266 |
| complexity of factors in sera of different mice that affect mtv-induced mammary tumor cells. | specific spleen cell activity in microcytotoxicity assay can be altered by pretreatment of target mammary tumor virus (mtv)-induced mammary tumor cells with serum. serum from both balb/cfc3h females neonatally infected with mtv and balb/c females horizontally exposed to mtv antigens will block specific spleen cell activity against isologous mammary tumor cells. on fractionation of sera, blocking factors are localized in the 7s fraction. the 19s fraction contains recruiting factors that are not d ... | 1976 | 176267 |
| characterization of mouse mammary tumor viruses from primary tumor cell cultures.i. immunologic and structural studies. | primary cell cultures of mammary tumors from rill, gr, dd, balb/cfc3h, and balb/c mice were prepared by trypsin-edta dissociation of tumors. cultures from these strains contained predominantly cells of epithelial morphology which formed three-dimensional domelike structures. cultures from rill, gr, dd, and balb/cfc3h tumors produced extra-cellular type-b mouse mammary tumor virus(es) (mumtv), either in the absence of detectable type-c virus or with less than 1% contamination with type-c virus. ... | 1976 | 176373 |
| characterization of mouse mammary tumor viruses from primary tumor cell cultures. ii. biochemical and biophysical studies. | primary mammary tumor cultures of riii, gr, dd, balb/c, and balb/cfc3h mice were examined for mouse mammary tumor virus (mumtv) production. levels of production of 12-32 mug virus protein/day/75-cm2 culture flask could be maintained for 30-50 days with daily virus harvests. the viruses from tumor cell cultures of these mouse strains contained dna polymerase with a strong preference for mg++ over mn++ as the divalent cation, a characteristic of dna polymerase of mumtv from mouse milk. these virus ... | 1976 | 176374 |
| genetic analysis of mammary tumor induction and expression of mammary tumor virus antigen in hormone-treated ovariectomized gr mice. | early stages of mammary tumors (emt) were induced with a combined treatment of progesterone (p) and estrone (e) in ovariectomized adult grs/a (gr) mice, a strain of european origin and with a high incidence of mammary cancer. the mammary tumors were comparable to the pregnancy-dependent tumors of breeding females of this strain. the hormone treatment did not lead to emt in a variety of other strains and only occasionally in the riii an c3h strains. treatment with p or e alone di not lead to emt ... | 1976 | 176379 |
| specificity of human antibodies to intracytoplasmic type-a particles of the murine mammary tumor virus. | large-scale studies showed that antibodies previously detectable in women with proliferating mastopathy or breast cancer were directed to intracytoplasmic type-a particles (iap) of mouse mammary tumor virus. immunofluorescence revealed the human antibodies to be bound only by those tumors producing a certain amount of iap clusters visible by light microscopy. the intensity of the reaction corresponded to the iap content of every tumor tested as revealed by electron microscopy and rabbit antisera ... | 1976 | 176384 |
| hydrodynamic diameters of murine mammary, rous sarcoma, and feline leukemia rna tumor viruses: studies by laser beat frequency light-scattering spectroscopy and electron microscopy. | we have studied purified preparations of murine mammary tumor virus (mumtv), rous sarcoma virus (rsv; prague strain), and feline leukemia virus (felv) by laser beat frequency light-scattering spectroscopy, ultra-centrifugation, and electron microscopy. the laser beat frequency light-scattering spectroscopy measurements yield the light-scattering intensity, weighted diffusion coefficients. the corresponding average hydrodynamic diameters, as calculated from the diffusion coefficients by the stoke ... | 1976 | 176431 |
| further characterization of intracytoplasmic a particle-associated dna. | a dna species with buoyant densities greater than mouse cellular dna was found associated with intracytoplasmic a particles (cap) isolated from mouse mammary tumor virus-infected mouse mammary tumors and mouse leydig cell tumors which produce cap but no complete mouse mammary tumor virus virions. this dna species was absent in identically prepared tissue fractions from tumors which did not contain cap. treatment of cap-associated dna with pancreatic rnase a did not alter the buoyant density alth ... | 1976 | 176446 |
| polypeptides of the mouse mammary tumor virus. ii. identification of two major glycoproteins with the viral structure. | | 1976 | 176790 |
| extrinsic labeling of mumtv with a galactose oxidase-tritiated borohydride method. | | 1976 | 176809 |
| [methods of obtaining antisera against antigens of the mammary cancer virus]. | the authors used various methods of producing virus-containing preparations from mouse mammary carcinoma to obtain rabbit antisera against the mammary carcinoma antigens. the best results were achieved by means of the virus precipitation from the cultural fluids of carcinomas growing in vitro after preliminary hormonal stimulation of the virus yield followed by its purification in the sucrose density gradient. | 1975 | 177127 |
| mouse mammary tumor virus as a model for viral carcinogenesis. | evidence is presented suggesting that genetic control may be the limiting factor in mammary tumor virus (mtv) positive mammary oncogenesis. studies with hybrid mice involving high and low mtv-expressing murine strains suggest that expression of mtv in milk may not be as important in tumorigenesis as previously thought. the usefulness of the murine mtv model in the study of mammary malignancy is discussed. | 1976 | 177786 |
| mammary gland as a morphological end point in carcinogenesis studies. | the murine mammary tumor system is characterized by the presence of intermediate preneoplastic mammary cell populations. the intermediate mammary cell populations are characterized as either alveolar hyperplasias or ductal hyperplasias. the most frequently encountered preneoplastic cell population is the hyperplastic alveolar nodule, which has been extensively characterized with respect to its biological and hormonal properties. while the alveolar hyperplasias are seen predominantly in mice infe ... | 1976 | 177787 |
| sialylatin of glycoproteins of murine mammary tumor virus, murine leukemia virus, and mason-pfizer monkey virus. | neuraminidase treatment of mouse mammary tumor virus, rauscher murine leukemia virus, and mason-pfizer monkey virus resulted in loss of their capacity to inhibit hemagglutination of influenza virus. hemagglutination-inhibition activity of these rna tumor viruses could be restored by in vitro resialylation catalyzed by sialyl transferase. the major glycoprotein in the intact envelope of desialylated and, to some extent, native virions could be specificallly labeled in vitro with cmp-(14c) sialic ... | 1976 | 178911 |
| murine mammary tumor virus: characterization of infection of nonmurine cells. | murine mammary tumor virus (mumtv) was used to productively infect feline and mink cells. mumtv "proviral" dna could be detected in the infected cells by molecular hybridization using radioactive mumtv complementary dna as a probe. kinetic analysis of mumtv proviral dna synthesis after infection showed that maximum mumtv dna synthesis was achieved by 8 h; however, this was followed by a decline in detectable proviral dna and eventual stabilization at a lower level. mumtv synthesis in feline cell ... | 1976 | 178928 |
| preneoplastic lesions in murine mammary cancer. | the current model for murine mammary tumorigenesis indicates that discrete, morphologically identifiable preneoplastic lesions precede and give rise to mammary tumors. the hyperplastic alveolar nodule is the primary lesion that precedes and gives rise to mammary tumors in mice infected with the mammary tumor virus (bittner) or its variants. in mice fed 7,12-dimethylbenzanthracene or urethan, hyperplastic alveolar nodules are present but infrequent, and the major mammary dysplasias present are du ... | 1976 | 179706 |
| autogenous immunity to mouse mammary tumor virus in mouse strains of high and low mammary tumor incidence. | specific radioimmune precipitation assays were utilized to demonstrate the presence of precipitating antibodies to mouse mammary tumor virus (mmtv) in the high-spontaneous mammary tumor strains of mice: c3h/hen+, gr/n, balb/cfc3h, and c57bl/6 x c3h f1 (hereafter called b6c3f1). antibody titers in c3h/hen+ mice increased with age, with highest titers observed in tumor-bearing animals. mmtv-precipitating antibodies were not detectable by radioimmune precipitation assay in low-mammary tumor strains ... | 1976 | 179709 |
| relationship between receptor and mammary tumour virus production after stimulation by glucocorticoid. | a short exposure of primary cultures of mouse mammary tumour cells to glucocorticoids results in at least a three-fold stimulation of mammary tumour virus (mtv) production. specific interaction of glucocorticoids with the cytoplasmic and nuclear receptors can also be demonstrated. the biological potency of various steroids to stimulate mtv is related directly to the retention of the steroid-receptor complex in the nuclei. progesterone has a high affinity for the cytoplasmic receptor, is not reta ... | 1976 | 180430 |
| [comparative antigenic analysis of j-96 cell oncornavirus and mason-pfizer virus from a spontaneous monkey mammary tumor]. | a comparative study of the antigenic structure of oncornavirus of j-96 cells and mason-pfizer virus (m-pvm) isolated from cells of m. rhesus spontaneous mammary tumour was carried out using immunodiffusion in agar, immune autoradiography and indirect immunofluorescence procedures. immune rabbit serum to disrupted j-96 virus detected by agar immunodiffusion in preparations or purified virus three soluble antigens one of which was identical to group-specific m-pvm antigen. | 1976 | 180692 |
| a biochemical approach to the study of the transmission of mouse mammary tumor viruses in mouse strains riii and c3h. | mouse mammary tumor virus (mmtv) proviral sequences were detected in the cellular dna of mammary tumors and livers of riii and c3h mice by molecular hybridization with radioactively labelled mmtv 60-70s rna or tritiated mmtv complementary dna (cdna). by means of dna:dna reassociation kinetics, the dna of the mammary tumor cells of these two mouse strains were found to contain more mmtv proviral sequences than the dna of liver cells of these same tumor-bearing mice. evidence is also presented tha ... | 1976 | 181334 |
| effect of trypsin on mouse mammary tumor virus. | undisrupted mouse mammary tumor virus (mumtv) derived from the milk of of riii mice has been analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopy after treatment with insolubilized trypsin. no alterations were found in viral fine structure by either freeze-etch or negative-stain electron microscopy. no alterations were found in the ability of trypsinized virus to compete in a radioimmune assay for viral antigens. infectivity experiments indicate no signif ... | 1976 | 181596 |
| differences between genomes of two strains of mouse mammary tumor virus as shown by partial rna sequence analysis. | | 1976 | 181905 |
| [effect of early thymectomy on the growth of transplanted mammary gland tumors developing in mouse line c3hf]. | mammary tumours which developed in factorless c3hf mice when transplanted to mtv-s+ and mtv-s- recipients were found to grow at the same rate' early thymectomy failed to influence their growth. the observed accelerated growth of mammary tumour transplants from c3h/he mice to mtv-s+ recipients, as compared to the mtv-s- ones, and inhibition of the tumour growth after early thymectomy seemed to be connected with the peculiarities of the immunological reaction to the virus-induced antigens. | 1976 | 182306 |
| high frequency variation in mammary tumor virus expression in cell culture. | clonal derivatives of c3hmt murine mammary cell lines in culture demonstrate conversion of mammary tumor virus (mmtv) expression at a rate of appriximately 6 per 100 clones. this alteration is largely unidirectional from a relatively high level (mmtv(h)) to a 10 fold lower level (mmtv(l)). this high rate of mmtv(l) variant conversion is in apparent contrast to the presumably mutational rate (approximately 3 per million cells) that governs development of resistance to 6-thioguanine (tg) in the sa ... | 1976 | 182380 |
| lack of interference in antigen production in vitro between b-type and c-type oncornaviruses as determined by double stain immunofluorescence. | | 1976 | 182499 |
| independent polypeptide chain initiation sites for the synthesis of different classes of proteins for an rna tumor virus: mouse mammary tumor virus. | | 1976 | 183363 |
| comparative studies of type c, type b, and m-pm oncornaviruses. | | 1975 | 183711 |
| mumtv-like characteristics of human breast carcinoma immunogens. | | 1975 | 183727 |
| virus-dependent cytostatic activity to mammary tumor cells of lymphocytes from normal mice. | a cytostasis assay has been used to study the natural immunity of mice to murine mammary tumor virus (mtv). spleen cells from adults of all strains tested were found to be cytostatic to a variety of mtv-positive mammary tumor cell lines. newborn spleen cells were unreactive in the same cytostasis assay. the degree of reactivity to the target cells was greater in spleen cell preparations from low mtv expressors than from syngeneic, high mtv expressors. the cytostasis was specific, since mtv antig ... | 1976 | 184922 |
| cellular hypersensitivity of gp55 of riii-murine mammary tumor virus and gp55-like protein of human breast cancers. | previous studies suggested that immunogenic breast cancer tissues contained a component(s) that is antigenically similar to some component of murine mammary tumor virus (mumtv) and resembles the glycoprotein, m.w. 55,000 (gp55), of riii-mumtv in molecular weight and charge density. this investigation measured in vitro cellular hypersensitivity responses of breast cancer patients to riii mouse milk, purified riii-gp55, c3h-mumtv, autologous and homologous breast cancer tissues, gp50 of a-mumtv, a ... | 1976 | 184925 |
| analysis of the transfer rna population of mouse mammary glands infected with a latent mammary tumor virus. | mammary gland transfer rna's (trna's) of ceh mice infected with mammary tumor virus were analyzed in the preneoplastic state and compared to trnas of virus-free c3hf mice and another uninfected strain, c57bl/6, which is completely resistant to cancer. this quantitative study was based on the ability of each trna to fix its corresponding amino acid. the amount of each of the 17 trna's tested was identical for the three mammary glands. in addition, trna populations during lactation correlated wit ... | 1976 | 184939 |
| prognostically significant protein components of human breast cancer tissues. | cryostat sections of clinicopathologically characterized breast cancer tissues were eluted with phosphate-buffered 0.9% sodium chloride solution, ph 7.2. the proteins were then characterized by polyacrylamide gel electrophoresis with and without prior treatment with sodium dodecyl sulfate. approximately 65% of the brease cancer tissue eluates contained a prominent protein fraction with a molecular weight of 47,000 to 55,000 (p50). no such component was found in 15 of 17 eluates of benign breast ... | 1976 | 184941 |
| detection of the major glycoproteins of friend leukemia virus (gp71) and the murine mammary tumor virus (gp52) on the surface of mouse cells. | specific rabbit antisera to the major glycoproteins of friend leukemia virus (gp71) and the mouse mammary tumor virus (gp52) were utilized to study the surfaces of c3h-, dba-, balb/c-, and c57bl-transformed and normal cells by immunoelectron microscopy. antiserum to gp71 showed reactivity with all of the mouse cells tested regardless of strain, virus production, or state of transformation. in cells producing murine leukemia virus, budding viruses and other areas of the cell surface were consiste ... | 1976 | 184944 |
| mouse mammary tumor virus in hybrids from strains c57bl and gr: breeding test of backcross segregants. | f1 and f2 and first backcross hybrids and second backcross families of the high mammary tumor incidence strain gr and the low incidence strain c57bl were examined for the segregation of mouse mammary tumor viral (mmtv) expression. although gr has been reported to transmit mmtv as a single dominant gene, several lines of evidence suggest there are multiple genetic factors that influence mmtv expression, mmtv expression as measured by double antibody radioimmunoassay for mmtv p14 segregated in 106 ... | 1976 | 185316 |
| rna complementary to the genome of rna tumor viruses in virions and virus-producing cells. | cells producing type c (avain sarcoma virus) or type b (mouse mammary tumor virus) rna tumor viruses contain small amounts of rna complementary to the viral genomes. the negative strands are complementary to at least 30 to 45% of the viral genomes and are found as rna-rna duplexes in the nucleus and cytoplasm of infected cells and in mature virions. | 1976 | 185416 |
| [structure of mouse mammary tumor virus particles]. | | 1976 | 185436 |
| nucleotide sequences in mouse dna and rna specific for moloney sarcoma virus. | complementary dna (cdna) synthesized by moloney murine sarcoma virus (m-msv) was separated into two parts, the first, termed msv-specific cdna, composed of nucleotide sequences found only in m-msv viral rna, and the second, termed msv-mulv common cdna, composed of nucleotide sequences that were found in both m-msv and murine leukemia virus (mulv) viral rnas. rna complementary to the msv-specific cdna was not found in several other msv isolates, nor in ecotropic mulv, mouse mammary tumor virus, o ... | 1976 | 185623 |
| viruses as an etiologic factor in cancer. | | 1976 | 185722 |
| the purification of a gs antigen of the murine mammary tumor virus and its quantitation by radioimmunoassay. | | 1976 | 185802 |
| further evidence for common antigens in intracytoplasmic a particles of mouse mammary tumors and b type virions of murine milk. | using the indirect immunofluorescence technique and radioimmunoprecipitation test (rip test) according to abelev and elgort (1970) immunological investigations intracytoplasmic a particles isolated from mouse mammary tumors were performed. in order to purify the virus particles sucrose gradients were employed according to tanaka et al. (1972) and in some details according to smith and wivel (1973). in immunofluorescence studies on mammary tumor slices a complete cross-reaction between antisera a ... | 1976 | 186295 |
| propagation of mouse mammary tumor cell lines and production of mouse mammary tumor virus in a serum-free medium. | five different mouse mammary tumor cell lines were propagated in a serum free medium. evaluation of growth characteristics, including logarithmic growth, cell population increase, protein production and days to confluency, showed serum-free medium comparable to serum-containing medium. mouse mammary tumor virus expression and production, in c3h and gr tumor cell lines, as determined by virus particle counting and rna dependent dna polymerase assays, subsequent to dexamethasone stimulation reveal ... | 1976 | 186396 |
| stimulation of immune mechanisms against mammary tumors by incomplete t cell depletion. | when balb/cfc3h females are subjected to continous suction thymectomy, a procedure that results in retention of thymic remnants, the latent period before tumor development is significantly prolonged. however, when balb/cfc3h females are thymectomized by control suction, a procedure which removes thymic lobes completely, there is no effect on mammary tumorigenesis. our results show that incomplete t cell depletion causes premature onset of non-t cell cytotoxicity, an augmentation of t cell cytoto ... | 1976 | 186535 |
| antibody-induced modulation and shedding of mammary tumor virus antigens on the surfaces of gr ascites leukemia cells as compared with normal antigens. | the distribution, antibody-induced redistribution, and shedding of murine mammary tumor virus (mumtv) antigens and the surfaces of gr mouse ascites leukemia (grsl) cells were studied by the immunoferritin technique and compared with the same activities of thy 1.2 and h-2.8 antigens. mumtv antigens were redistributed easily and then largely shed from the cell surface; in contrast, h-2.8 antigen moved easily and probably was partially released from the plasms membrane and thy 1.2 antigen moved slo ... | 1976 | 186612 |
| oncornavirus-like particles in baboon type c virus-infected chimpanzee lung cells (sfre:cl-1). | intracytoplasmic type a particles were observed in a fetal chimpanzee lung culture (sfre:cl-1) inoculated with type c virus-containing supernatants from a coculture of baboon placenta and sfre:cl-1 cells. budding, immature, and mature type c particles were also noted. in thin section, spike-like structures were rarely detected on budding intracytoplasmic type a particles but were occasionally observed on some immature and mature virus particles. unlike mouse mammary tumor virus or mason-pfizer m ... | 1976 | 186614 |
| hormone synergism in the in vitro production of the mouse mammary tumor virus. | the production of mouse mammary tumor virus (mmtv) in primary cell cultures of balb/cfc3h mammary tumor cells was measured by radioimmune assay and rna=dependent dna polymerase activity. maximum virus production was dependent on cell density, nutritional milieu, and hormone supplementation. the addition of insulin (u), estradiol-17 beta (e2), progesterone (p), prolactin (prl), or thyroxine (t3) alone had little or no effect on mmtv production. hydrocortisone (f) had a primary stimulatory effect. ... | 1976 | 186627 |
| plasma levels of a viral protein as a diagnostic signal for the presence of tumor : the murine mammary tumor model. | we used the mouse mammary tumor and its associated virus (murine mammary tumor virus) to examine the possibility of using plasma levels of a viral protein (gp52, the glycoprotein of 52,000 molecular weight) as a diagnostic indicator of the presence of a solid tumor. the following features have emerged from our studies: (a) tumor-bearing animals show markedly elevated (100-1000 ng/ml) plasma levels of gp52 and the mean concentration increases with tumor size; (b) mammary tumor tissues located out ... | 1976 | 186789 |
| mammary tumour virus (mtv)-specific immune complex deposites in renal glomeruli of mtv-infected tumour-free mice. | using direct and indirect immunofluorescence tests mtv-specific immune complex deposits were found in tumour-free female mice of the strains c3h/bln, cba/bln, xvii/blnfcba/bln, and cba/blnfxvii/bln. these deposits consist of immunoglobulin, complement, and mtv antigen(s). the immune complex deposition increases with age. antibodies eluted from renal tissue homogenate react with both mtv-a and -b particles in immunofluorescence tests performed on mouse mammary tumour slices. by these results the ... | 1976 | 186993 |
| two-way selection of a stock of swiss albino mice for mammary tumorigenesis: establishment of two new strains (shn and sln). | two mouse strains (shn and sln) with high and low incidences, respectively, of mammary tumors were established from the same basal stock of swiss albino mice that were unrelated in origin to other mouse strains with mammary tumors. in the breeders, mammary tumor incidence and average age of the mice when they developed mammary tumors were 97.2 % and 6.6 months for shn, and 5.57% and 10.1 months for sln, respectively... | 1976 | 187774 |
| in vitro susceptibility of mink lung cells to the mouse mammary tumor virus. | lung cells from mink embryos were infected in vitro with a purified mammary tumor virus isolated from riii mouse milk. specific virus antigen at the cell surface was detected by membrane immunofluorescence; b-type virions budding from the cell membrane were seen by electron microscopy. nucleic acid hybridization confirmed replication and specificity of the virus produced. | 1976 | 187775 |
| biologic characteristics of some mouse mammary tumor viruses. | the mammary tumor virus (mumtv) in the milks of 7 mouse strains and substrains was titrated for infectivity in 4 strains. the data indicated that: 1) each strain shed a different mumtv and some genetic strains carried two mumtv's, each discernible by its mouse strain preference in infectivity tests. 2) less than 5% of riiif and about 10% of af mice shed detectable mumtv antigen in their milks after the third parturition. after the sixth parturition, 33% of riiif and 50% of af, and after the nint ... | 1976 | 187780 |
| long-term effects of neonatal steroid exposure on mammary gland development and tumorigenesis in mice. | newborn female mice of three strains--balb/cfc3h [mammary tumor virus (mumtv)-infected], balb/c, and c57bl (both virus-free)--were given injections of 17beta-estradiol or testosterone, alone or in combination with ovine prolactin, for the first 5 days of life. half of each group of mice were ovariectomized at 40 days of age, and all mice were killed between 6 and 16 months of age. mammary glands of balb/cfc3h mice receiving steroid hormones were better developed than those of mice not receiving ... | 1976 | 187788 |
| mammary tumorigenesis in chemical carcinogen-treated mice. vi. tumor-producing capabilities of mammary dysplasias in balb/ccrgl mice. | two types of mammary dysplasias occurring in 7,12-dimethylbenz[a]anthracene (dmba)-treated balb/ccrgl mice were transplanted into the cleared mammary fat pads of syngeneic mice for an assessment of their growth behavior and tumor potentials. keratinized nodules, numerous in dmba-treated, pituitary isograft-bearing balb/ccrgl mice, produced primarily ductal outgrowth in control mice and very few tumors (7%) 56 weeks after transplantation. such dysplasias transplanted into mice bearing pituitary i ... | 1976 | 187796 |
| [etiopathogenic factors of breast cancer (2)]. | | 1976 | 188082 |
| surface structure of virions budding from l1210(v) gln- mouse leukemia cells. | | 1976 | 188241 |