| ubiquity of natural antibodies to the mammary tumour virus in mice. | sera of female and male mice from eleven inbred mouse strains collected at either 4, 12, 36 or 60 weeks of age were tested for the presence of natural antibodies to the murine mammary tumour virus by means of the sepharose bead immunofluorescence assay. antibodies to the virus proved to be ubiquitous, but pronounced strain differences were found in titer and onset of antibody production. these differences were related to neither release of virus in the milk nor susceptibility to spontaneous mamm ... | 1980 | 6254462 |
| antigenic modulation of mammary tumour virus envelope antigen or gr thymic lymphoma cells in relation to expressions of h-2, tl cell-surface antigens and thy1. | the mlr antigen, a mammary tumour virus-induced antigen on the surface of gr thymic lymphoma cells (grsl) can be modulated from the cell surface upon incubation with specific antiserum for 1-2 h at 37 degrees c, followed by washing the cells. in contrast, a number of other cell-surface antigens on these grsl cells cannot be modulated under similar conditions. these antigens include histocompatibility antigens of the h-2 complex (h-2.8 of the k-end and h-2dx(d) of the h-2dx haplotype) and two thy ... | 1980 | 6254554 |
| a unique glycoprotein containing gr-mouse mammary tumor virus peptides and additional peptides unrelated to viral structural proteins. | a glycoprotein of molecular weight 130,000 (gp130) has been precipitated from the cytoplasm of gr-strain mouse mammary tumor (gr-mmt) cells by a rabbit antiserum (anti-mmtv) to gr-strain mouse mammary tumor virus (gr-mmtv). this protein was not precipitated by antisera specific for detergent-disrupted c3h-strain mmtv (c3h-mmtv); c3h-mmtv glycoproteins; c3h-mmtv nonglycosylated proteins; gr-mmtv p25 or p12; riii strain (milk) mmtv proteins; or rauscher murine leukemia virus (r-mulv) proteins; nor ... | 1980 | 6254670 |
| dna binding and unwinding activities associated with intracytoplasmic a particles isolated from mouse mammary tumors. | intracytoplasmic a particles (cap), previously identified as probably cytoplasmic nucleocapsid precursor structures to mouse mammary tumour virus (mmtv), possess both dna binding and dna unwinding activities, cap proteins bind to both single-stranded (ss)- and double-stranded (ds)dna, with the ssdna slightly preferred. this activity was linear over a 30-fold concentration of a particle protein and was not affected by nacl concentrations as high as 0.6 m or ph changes over a wide range. dna bindi ... | 1980 | 6255067 |
| proviruses of mouse mammary tumor virus in normal and neoplastic tissues from gr and c3hf mouse strains. | we analyzed two experimental situations to assess the role of endogenous mouse mammary tumor virus (mmtv) dna in the genesis of mammary carcinomas. (i) gr mice carry in their germ line one or more proviruses indistinguishable by limited restriction mapping from the proviruses introduced into cells by experimental infection with the highly tumorigenic virus isolated from gr mouse milk, mmtv(gr). most tumors arising in gr mice contain one or more proviruses at various sites in tumor dna in additio ... | 1980 | 6255172 |
| analysis of secondary modifications of mouse mammary tumor virus proteins by two-dimensional gel electrophoresis. | the structural proteins of mouse mammary tumor virus (mmtv) were analyzed by two-dimensional electrophoresis on isoelectric focusing and sodium dodecyl sulfate gels. many of the viral proteins displayed heterogeneity in charge due to variable contents of carbohydrates (in particular, sialic acid) and phosphate residues. neuraminidase treatment of the virions influenced the isoelectric pattern of the envelope glycoproteins. the glycoproteins of an mmtv variant which was attenuated by replication ... | 1980 | 6255175 |
| structure and processing of the mouse mammary tumor virus glycoprotein precursor pr73env. | the polyprotein precursor to the envelope glycoproteins of mouse mammary tumor virus was investigated by using subcellular fractionation procedures, pactomycin mapping techniques, tunicamycin inhibition of glycosylation, and endo-beta-n-acetyl glucosaminidase h-catalyzed removal of glycosylated residues in order to characterize the biosynthesis and processing of the precursor. the results suggest that the precursor (pr73env) is synthesized on the rough endoplasmic reticulum as a transmembrane pr ... | 1980 | 6255176 |
| selective amplification of mouse mammary tumor virus in mammary tumors of gr mice. | dnas extracted from the mammary tumors of gr mice were analyzed for mouse mammary tumor virus proviral sequences by the restriction enzyme-southern blot procedure. the tumor dnas contain more proviral copies of mouse mammary tumor virus than dna from a nonmalignant tissue. the degree of proviral amplification is small (ca. one to five additional copies) and appears to be variable from tumor to tumor. the restriction patterns of the amplified proviral sequences suggest a clonal origin for the tum ... | 1980 | 6255199 |
| the extraction by micrococcal nuclease of glucocorticoid receptors and mouse mammary tumor virus dna sequences is dissociated. | glucocorticoid receptors (rg) and mammary tumor virus (mm-tv) dna sequences were extracted by micrococcal nuclease digestion from the nuclei of c3h mouse mammary tumor cells in order to specify their relative distribution in chromatin. rg was labelled and translocated into the nuclei by incubating cells with 3h dexamethasone (3h dex). the purified nuclei were then treated at 2 degrees c with micrococcal nuclease. three chromatin fractions were successively obtained: an isotonic extract (ne3h1), ... | 1980 | 6255415 |
| antigens and antibodies cross-reactive to the murine mammary tumor virus in human breast cyst fluids. | human breast cyst fluids were shown to contain low concentrations of iga (15-78 micrograms/ml) and igg (33-145 micrograms/ml). the iga:igg ratios in individual breast cyst fluids ranged from 1:0.6 to 1:4. these levels are considerably higher than their ratio in serum (1:7). iga from 33% of the 40 fluids examined, and igg from 10% of the fluids, reacted with the murine mammary tumor virus (mumtv). the reactivity was detected by an enzyme-linked immunosorbent assay that measures antibody binding t ... | 1981 | 6256413 |
| kinetics of responses to tumor antigens and mouse mammary tumor virus in balb/ccrgl and balb/cfc3h mice. | spleen cells from balb/ccrgl mice responded to murine mammary tumor virus (mumtv) in cell-mediated immune assays at higher levels than did the spleen cells from the syngeneic balb/cfc3h mice. implantation in balb/ccrgl with a chemically induced mammary tumor and in balb/cfcrgl mice with spontaneous mammary tumors (smt) arising in the same strain resulted in sensitization of these animals to the antigens of their tumors. reactivities peaked 3 weeks after transplantation, whereas no positive react ... | 1981 | 6256573 |
| development, morphology, and progression of mammary tumors during and after fertile life in balb/cfriii mice. | a study was done on 368 balb/cfriii mammary tumor-bearing breeding female mice that are of the balb/c genotype and carry milk-transmitted riii murine mammary tumor virus (mumtv) infection initiated by foster-nursing. all tumors were characterized by chronologic, biologic, and morphologic analyses. mammary tumors occurring during pregnancy-lactation periods were mostly pregnancy-dependent plaques showing organoid tubular structure, sudden growth during late pregnancy, regression after delivery, a ... | 1981 | 6256576 |
| nucleotide sequences at host-proviral junctions for mouse mammary tumour virus. | proviruses cloned from rat cells infected with mouse mammary tumour virus, a b-type retrovirus regulated by glucocorticoid hormones, show the structural features of transposable elements: short inverted repeats conclude long direct repeats at the ends of viral dna, and short sequences of cellular dna are duplicated during integration and flank each provirus. the integrative mechanism joins a precise site in viral dna to non-homologous sites in host dna. | 1981 | 6256658 |
| noncoordinate expression of murine mammary tumor virus gene products. | | 1980 | 6256936 |
| subset of spleen lymphocytes from balb/ccrgl mice stimulated by mouse mammary tumor virus. | lymphocytes from balb/ccrgl mice react to mouse mammary tumor virus-associated antigen(s) when tested in in vitro blastogenic transformation assays. these mice have a low incidence (less than 1%) of spontaneous mammary tumors and are free from complete mammary tumor virions. we have studied the nature of the lymphoid cells mediating the lymphocyte transformation reaction to purified mammary tumor virus. with the use of nylon wool columns, the responder cells were found to belong to the nylon-adh ... | 1981 | 6257384 |
| characterization of endogenous and exogenous mouse mammary tumor virus proviral dna with site-specific molecular clones. | restriction fragments of the mouse mammary tumor virus (mmtv) proviral dna were obtained by molecular cloning procedures. a 4-kilobase fragment delimited by two psti sites was isolated from unintegrated, linear mmtv dna and amplified in the pbr322 plasmid vector. ecori fragments of proviral dna, integrated into the genome of a gr mammary tumor cell line, were isolated as lambda recombinant molecules. five different recombinant phages which contained the 3' region of the mmtv proviral dna and adj ... | 1980 | 6257924 |
| identification and partial characterization of an endogenous form of mouse mammary tumor virus that is transcribed into the virion-associated rna genome. | restriction mapping demonstrated the presence of several distinct proviral forms of mouse mammary tumor virus in the genome of gr mice. one of these proviruses (gr-mtv-2) was highly amplified in gr 3a cells, a cell line derived from a gr mammary tumor. by the criterion of restriction mapping, the amplified gr-mtv-2 provirus found in gr 3a cells was identical to the provirus found in m1.19 cells, a rat cell line infected with virions obtained from gr 3a culture fluid. this result clearly implies ... | 1980 | 6258150 |
| precursor product relationship between intracytoplasmic a particle and murine mammary tumor virus core proteins established by tryptic peptide analysis. | | 1981 | 6258309 |
| development and characterization of mouse hyperplastic mammary outgrowth lines from balb/cfc3h hyperplastic alveolar nodules. | five hyperplastic outgrowth lines were developed by serial transplantation of hyperplastic alveolar nodules from balb/cfc3h mice into balb/c hosts. the lines were used to study the biology, morphology, and virology of premalignant tissue originating in mouse mammary tumor virus (mumtv)-positive animals. the five lines differed with respect to tumor potential and growth characteristics, corroborating the previous evidence that mumtv-positive hyperplastic alveolar nodules are biologically heteroge ... | 1980 | 6258774 |
| cloned mouse mammary tumor virus dna is biologically active in transfected mouse cells and its expression is stimulated by glucocorticoid hormones. | we have cloned circular unintegrated mouse mammary tumor virus (mmtv) dna from infected rat hepatoma cells in bacteriophage lambda. seven independent clones containing mmtv dna of homogeneous length of 9 kb (five) or 10 kb (two) were identified. the five 9 kb clones had identical restriction maps consistent with that of 9 kb unintegrated dna; the other two were aberrant. mmtv dna inserts were purified, ligated and used for cotransfection of ltk- cells together with a plasmid containing the thymi ... | 1981 | 6258799 |
| common surface receptors on both mouse and rat cells distinguish different classes of mouse mammary tumor viruses. | | 1981 | 6259809 |
| characterization of a variant-producing tumor cell line from a heterogeneous strain balb/cfc3h mouse mammary tumor. | | 1981 | 6260334 |
| changes in retrovirus expression in mouse mammary tumor cells in culture. | mouse mammary tumor cells (mm5mt/c1) produced mouse mammary tumor virus (mmtv) (type b retrovirus) at early passages in culture. they apparently produced predominently type c retrovirus(es) at late passages in culture. the decline in mmtv production during passage was not accompanied by an apparent decrease in the synthesis or accumulation of intracellular mmtv-specific rna. as judged by the concentration of rna (mol/titer) x half-time (sec) of hybridization of cellular rna with mmtv complementa ... | 1981 | 6260345 |
| mammary tumor induction loci in gr and dbaf mice contain one provirus of the mouse mammary tumor virus. | the mammary tumor induction genes mtv-1 in mouse strain dbaf and mtv-2 in strain gr control the complete expression of the endogenous mouse mammary tumor virus (mmtv). we have used a combination of genetic, biochemical and molecular biological methods to identify and correlate specific copies of the endogenous mmtv proviral genes with the biological properties of the tumor induction genes mtv-1 and mtv-2. these mtv induction genes contain specific mmtv proviral information, as was concluded from ... | 1981 | 6260372 |
| the nature of cancer and the mechanisms of its control: a review. | observations on the nature of spontaneous tumours of mammary gland origin in mice, published over a 60-year period in 320 papers, are reviewed. data presented are (1) development of adequate experimental mice; (2) comparative studies on transplantable, chemically induced and spontaneous tumours by diverse genetic procedures, and (3) tumour regressions obtained with nucleosides. the fundamental conclusion derived from these data is that a genetic change, comparable to a somatic mutation, is invol ... | 1980 | 6260434 |
| virus-specific cytotoxic activity to mammary tumor cells of sera from normal and tumor-bearing mice with inhibition at low dilutions. | sera from normal mice and mice bearing murine mammary tumor virus (mtv)-induced tumors showed cytotoxic reactions to the mtv-producing mm5mt/c1 cell line. the reaction could be blocked by the addition of mtv, but not of purified gp52 and p28. in sera from tumor bearers, cytotoxic responses ranged from 15 to 66%; reactivity was generally highest when the serum was diluted 32 to 128 times. the cytotoxic sera from the normal animals showed a much lower activity; again, there was a lack of cytotoxic ... | 1981 | 6260679 |
| the effect of diet on autogenous immunity to mouse mammary tumor virus in c3h/bi mice. | antibody levels to mouse mammary tumor virus (mumtv) in sera of c3h/bi, c57bl/6 and akr mice were assayed by an enzyme-linked immunosorbent assay (elisa). it was found that antibody levels to mumtv were highest in sera of c3h/bi females which have a high incidence of breast cancer and low in male c3h/bi and female c3h/bi foster-nursed on c57bl/6 females. sera of c57bl/6 and akr mice showed very low or undetectable levels of antibody to mumtv. reduction of caloric intake sufficient to inhibit mam ... | 1980 | 6260696 |
| synthesis of plus strands of retroviral dna in cells infected with avian sarcoma virus and mouse mammary tumor virus. | the vast majority of plus strands synthesized in quail cells acutely infected with avian sarcoma virus were subgenomic in size, generally less than 3 kilobases (kb). a series of discrete species could be identified after agarose gel electrophoresis by annealing with various complementary dnas, indicating specificity in the initiation and termination of plus strands. the first plus strand to appear (within 2 h postinfection) was similar in length to the long redundancy at the ends of linear dna ( ... | 1981 | 6260968 |
| regulatory and coding potential of the mouse mammary tumor virus long terminal redundancy. | molecular clones containing the 3' half of newly integrated mouse mammary tumor virus (mmtv) dna with adjacent mouse cellular sequences were characterized. in addition, we cloned the long terminal redundancy joint from the unintegrated circular form of mmtv dna. the entire nucleotide sequence of the integrated and part of the unintegrated terminal redundancy was determined; this allowed us to delineate the boundaries of the mmtv long terminal redundancy, which comprises 1,327 base pairs. the pos ... | 1981 | 6260976 |
| protein-coding potential of mouse mammary tumor virus genome rna as examined by in vitro translation. | the protein-coding capacity of the mouse mammary tumor virus genome has been examined by in vitro translation of genome length and polyadenylated subgenomic fragments of viral rna. intact genome rna of about 35s programmed synthesis of the pr77gag, pr110gag and pr160gag/pol precursors seen in infected cells in vivo. polyadenylated rna fragments of 18 to 28s encoded products whose tryptic peptide maps resembled those of the nonglycosylated precursor to the envelope glycoproteins, confirming the g ... | 1981 | 6260988 |
| attempts to obtain monoclonal antibody against mmtv tumors. | | 1980 | 6261429 |
| the origin and structure of endogenous retroviral dna. | dna related to the genomes of avian leukosis viruses (alv) and mouse mammary tumor viruses (mmtv) is widely distributed among normal chickens and mice. we have used restriction mapping techniques to compare individuals from inbred and outbred populations with respect to genetically-transmitted proviral dna, in efforts to understand its origins and functions. we have found that outbred animals have variable numbers of alv and mmtv proviruses located at various sites in their host genomes, with so ... | 1980 | 6261653 |
| selenium-mediated inhibition of mouse mammary tumorigenesis. | the effects of selenium of mouse mammary tumorigenesis were examined in 2 systems. balb/cfc3h (mumtv-s positive) given 2 and 6 ppm selenium in the drinking water and maintained as breeding mice, had significantly lower incidences of mammary tumors (48% and 12%, respectively) than untreated control mice (82%). selenium at 4 ppm inhibited the tumor-producing capabilities of only 1 of 4 preneoplastic outgrowth lines maintained in balb/c (mumtv-s negative) mice. selenium at 2, 4 and 6 ppm had no eff ... | 1980 | 6261942 |
| expression of mouse mammary tumour virus related antigens in experimentally induced leukaemias of strain icrc. | | 1980 | 6262218 |
| distribution of mouse mammary tumour virus antigens in riii mice as detected by immunofluorescence on tissue sections and by immunoassays in sera and organ extracts. | organs of riii mice at various physiological stages were tested for mouse mammary tumour virus (mmtv) antigen expression. indirect immunofluorescence was used with three monospecific antisera to localize one envelope glycoprotein, gp47, and two core proteins, p28 and p8. these virus-specific antigens gave characteristic fluorescent patterns in the mammary tissues and were also detected in thymus and salivary gland sections of some mice. the amounts of antigens gp47 and p28 were measured by immun ... | 1980 | 6262440 |
| synthesis of murine mammary tumor viral proteins in vitro. | the coding potential of murine mammary tumor viral genomic rna was investigated by in vitro translation of various size classes of rnas isolated from the virions. the major products of translation of full-size 35s polyadenylylated virion rna were gag-related polyproteins of 75,000, 105,000, and 180,000 daltons (p75, p105, and p180, respectively). studies on the kinetics of translation of these three proteins established that they were synthesized independently and that the smaller proteins were ... | 1981 | 6262538 |
| accelerated mammary cancer development by fetal salivary mesenchyma isografted to adult mouse mammary epithelium. | transplantation of fetal salivary mesenchyma into adult mammary glands resulted in atypical outgrowths from the mammary duct system. these duct-alveolus nodules (dan) were distinguishable from hyperplastic alveolar nodules (han) that arose from normal mammary duct systems in mice infected with murine mammary tumor virus (mumtv). dan displayed a type of ductal branching characteristic of salivary gland rather than of mammary gland, reflecting a tissue-specific perturbation of epithelium-mesenchym ... | 1981 | 6262561 |
| in vitro synthesis of polypeptides encoded by the long terminal repeat region of mouse mammary tumour virus dna. | | 1981 | 6262660 |
| sandwich enzyme immunoassay of mouse mammary tumor virus. | | 1981 | 6263672 |
| partial expression of endogenous mouse mammary tumor virus in mammary tumors induced in balb/c mice by chemical, hormonal, and physical agents. | the possible interaction of environmental factors with the endogenous mouse mammary tumor virus (mmtv) genome in the development of mammary tumors in the low-tumor-incidence balb/c mouse strain was examined. tumors were induced in virgin female animals by treatment with chemical carcinogen 7,12- dimethylbenz[alpha]anthracene or urethan, with or without prolonged hormonal stimulation, or by x-irradiation. concomitant hormonal stimulation resulted in increased tumor incidences compared with those ... | 1981 | 6264129 |
| monoclonal antibodies against antigens displayed on a progressively growing mammary tumor. | we have produced lymphocyte hybridomas between mouse myeloma cells and either spleen cells of c3h/f/c57bl/6 mice bearing the mm5mt/c1 tumor-producing murine mammary tumor virus (mmtv) or spleen cells from fisher rats inoculated with the same tumor. two classes of hybridoma-secreted monoclonal antibodies were obtained. in the first class are ivc11, iiia1, and ve7, each of which precipitated a 52,000-dalton protein from 125i-labeled purified preparations of mmtv and [3h]glucosamine-labeled mm5mt/c ... | 1981 | 6264447 |
| hormone-responsive expression of an endogenous proviral gene of mouse mammary tumor virus after molecular cloning and gene transfer into cultured cells. | a recombinant lambda phage containing mouse mammary tumor virus (mmtv) proviral dna was isolated from a gene library constructed from gr mouse liver dna. restriction enzyme analyses reveal that the cloned molecule contains a copy of one of the gr endogenous mmtv proviruses flanked on both sides by 2--3 kb of mouse genomic dna. in this report we have examined the expression of the cloned mmtv provirus after cotransfection with the herpes thymidine kinase (tk; atp:thymidine 5'-phosphotransferase,, ... | 1981 | 6264458 |
| antibodies reactive with murine mammary tumor virus in sera of patients with breast cancer: geographic and family studies. | sera of patients with breast cancer, of healthy women from the united states, east india, east africa, and china, and of healthy women of american and parsi families in which breast cancer occurred in several family members were assayed for levels of antibody reactive with the murine mammary tumor virus (mumtv) by an enzyme-linked immunosorbent assay. increased levels of antibody to mumtv (absorbance greater than or equal to 0.4) were found in sera of 18.6% of american patients with breast cance ... | 1981 | 6264479 |
| viral epitopes and monoclonal antibodies: isolation of blocking antibodies that inhibit virus neutralization. | the inability of pathogenic animal viruses to be completely neutralized by antibodies can lead to chronic viral infections in which infectious virus persists even in the presence of excess neutralizing antibody. a mechanism that results in this nonneutralized fraction of virus was defined by the topographical relationships of viral epitopes identified with monoclonal antibodies wherein monoclonal antibodies bind to virus and sterically block the binding of neutralizing antibodies. | 1981 | 6264601 |
| geographic and family studies of immunological responses to antigens of the murine mammary tumor virus in sera of patients with breast cancer. | sera of breast cancer patients from the united states, india, east africa and china as well as from their families and from healthy women were assayed for antibodies reactive with the murine mammary tumor virus (mumtv). detection was by an enzyme-linked immunoassay recently developed in our laboratory. in the women with breast cancer, 62% of the east africans, 28% of the indians, 19% of the americans but only 5% of the chinese had antibody to mumtv. among healthy women, 21% of the africans, 3% o ... | 1980 | 6264656 |
| restriction endonuclease studies of hyperplastic outgrowth lines from balb/cfc3h mouse hyperplastic mammary nodules. | the dna's isolated from five mouse hyperplastic mammary gland outgrowth lines from balb/cfc3h mice were digested with the restriction endonucleases psti, bamhi, or ecori; electrophoresed; and analyzed by southern blotting and autoradiography. proviral dna sequences from the acquired c3h mouse mammary tumor virus were detected in the dna of all five lines, indicating that they were infected. the dna of the five hyperplastic lines contained more ecori and bamhi mouse mammary tumor virus proviral d ... | 1981 | 6265073 |
| hormones, chemicals and proviral gene expression as contributing factors during mammary carcinogenesis in c3h/stwi mice. | | 1981 | 6265386 |
| induction of type-c retrovirus by the tumor promotor tpa. | the tumor promotor 12-0-tetradecanoyl-phorbol-13-acetate (tpa) induced endogenous murine xenotropic type-c retrovirus from a1-2 cells, derived from the balb/c mouse, as determined by infectious center focus-forming assay on permissive normal rat kidney (nrk) cells. kinetic dose-response studies showed that the number of cells induced to release virus was dependent on tpa concentration and the time of assay following tpa exposure. maximal induction occurred when cells were treated with 80 ng/ml o ... | 1981 | 6265387 |
| lack of thy 1.2 antigen expression on the surfaces of mouse mammary epithelial cells. | monoclonal antisera against mouse thy 1.2 antigen were used to assess the expression of thy 1.2 antigen on balb/c and balb/cfc3h normal mouse mammary gland epithelial cells (mmec) and on spontaneous and transplanted balb/cfc3h mammary adenocarcinoma cells. immunofluorescence (if) assays with the monoclonal anti-thy 1.2 sera demonstrated that thy 1.2 antigen was not expressed on the surface membranes of mmec (both virus-free balb/c and virus-infected balb/cfc3h) and tumor (balb/cfc3h) mammary epi ... | 1981 | 6265679 |
| murine mammary tumor virus seroepidemiology in balb/cfc3h mice: correlation with tumor development. | serum reactivity to murine mammary tumor virus (mumtv) was inversely related to mammary tumor risk in 8-to 22-week-old balb/cfc3h breeding females. mice at low tumor risk exhibited high-titered serum reactivity to mumtv (50% end point, greater than or equal to 1:40 by radioimmunoassay) approximately 3-6 months earlier than did the mice at high tumor risk. maternal mumtv antibody levels were correlated with the serum anti-mumtv reactivity of their neonatal offspring (2 wk of age). serologic antiv ... | 1981 | 6265680 |
| chromatographic evidence that the aaa-coding isoacceptor of lysine trna primes dna synthesis in murine mammary tumor virus. | | 1981 | 6266151 |
| antibodies to mouse mammary tumor virus-related antigen in sera of patients with breast carcinoma. | sera from patients with breast carcinoma, benign breast disease, malignancies other than breast carcinoma, and healthy female controls were analyzed by indirect immunofluorescence for the presence of antibodies directed toward antigens of mouse mammary tumor. sera from 56 to 137 (40.9%) patients with breast carcinoma were positive. positive reactivity was also found in sera from 5 to 27 (18.5%) patients with benign breast disease, in 7 of 60 (11.7%) patients with malignancies other than breast c ... | 1981 | 6266639 |
| mammary tumorigenicities of three chemically induced mouse kidney cell lines in syngeneic female hosts. | three chemically induced, mammary tumour virus (mmtv) and leukemia virus (mulv) producing, baby mouse kidney (bmk) cell lines derived from respectively strains balb/c (-/hea and -/crgla) and c57bl/lia were investigated for their mammary tumour (mt) evoking potentials in syngeneic female hosts. an i.p. inoculated virus-enriched fraction from a3 cells (balb/c/hea) had a similar oncogenic effect as i.p. and s.c. inoculated whole a3 cells. the average mt ages were reduced in all 3 groups. cell lines ... | 1981 | 6266652 |
| integration and activity of mammary tumor virus genes: regulation by hormone receptors and chromosomal position. | | 1981 | 6266760 |
| enzymoimmunoassay of the main core protein (p28) of mouse mammary tumour virus (mmtv). | | 1981 | 6266832 |
| lymphoproliferative responses to mouse mammary tumor virus in lymphocyte subsets of breast cancer patients. | altered immunologic reactions were observed in breast cancer patients as compared to those in normal subjects. lymphoproliferative responses to murine mammary tumor virus (mumtv) were significantly enhanced in peripheral blood mononuclear cells from patients with metastatic disease. these reactivities occurred with mammary tumor virus purified from either mouse milk or infected feline kidney cells but not with rauscher murine leukemia virus. for the assessment of the role of peripheral blood mon ... | 1981 | 6267344 |
| mammary tumors from gr mice contain more than one population of mouse mammary tumor virus-infected cells. | | 1981 | 6267780 |
| immunological reaction between sera from neutron-irradiated w/fu rats and mouse mammary tumor virus. | sera from w/fu rats from the presence of anti mouse mammary tumor virus (mmtv) antibodies were examined by the use of an immunofluorescence (if) test and an immune adherence hemagglutination (iaha) test. sera from w/fu rats subjected to neutron irradiation or neutron irradiation followed by grafting of pituitary tumor (mtt) as a source of prolactin gave a positive if reaction with mouse mammary tumor cells (mmt) producing type-a and type-b virus particles. nine out of 20 (45.0%) sera from rats g ... | 1981 | 6268478 |
| purification and translation of murine mammary tumor virus mrna's. | we have studied the functions of the intracellular rnas of mouse mammary tumor virus (mmtv) by purification and translation in vitro. two major size classes of mmtv rna, 35s and 24s rna, were isolated from mmtv-infected rat (xc) cells and cultured mammary tumor cells by preparative hybridization of whole cell or polyadenylated rna to cloned mmtv dna covalently bound to chemically activated paper disks (diazobenzyloxymethyl paper). genomic-length (35s) rna was prepared free of 24s rna by rate zon ... | 1981 | 6268810 |
| mammary tumor virus proviral dna in normal murine tissue and non-virally induced mammary tumors. | the southern dna filter transfer technique was used to study the involvement of the endogenous mouse mammary tumor virus (mmtv) in the development of mammary tumors of nonviral etiology. the presence of extra mmtv proviruses in the genomes of these non-virally induced mammary tumors would indicate an integration of the provirus of an activated endogenous mmtv. acquisition of mmtv proviruses did not seem to be an absolute requirement for the development of hormone or carcinogenically induced mamm ... | 1981 | 6268828 |
| induction of endogenous mammary tumor virus expression during hormonal induction of mammary adenoacanthomas and carcinomas of balb/c female mice. | treatment of balb/c female mice with pituitary isografts, under conditions that established mammary hyperplasia in an anovulatory condition, enhanced mammary tumor development with prior onset of dysplastic foci in lobular parenchyma. tumor onset began at 8 months (mean onset time, 18 mo); the 25-month incidence was 100%. adenoacanthomatous tumors appeared first. adenocarcinomas appeared only after more than 14 months of continuous hormone stimulation. dysplastic and neoplastic changes occurred ... | 1981 | 6268884 |
| isolation and characterization of a new mouse mammary tumor virus from balb/c mice. | | 1981 | 6269283 |
| effect of the age-related immune depression induced by mtv on the in vivo growth of a mammary carcinoma. | | 1981 | 6269570 |
| quantitation of viral antigens released into plasma and culture fluids by murine mammary tumor cells. | radioimmunoassay capable of measuring mouse mammary tumor virus (mmtv) 52,000 m.w. envelope glycoprotein (gp52) and 27,000 m.w. protein (p27) have been used to quantitatively compare plasma concentrations of these viral antigens in mice bearing spontaneous mammary tumors. although gp52 was detected in the plasma of all tumor-bearing mice tested, p27 was detected in only a portion of tumor-bearing animals. in p27-positive animals, gp52 was detected in higher concentrations than p27. these finding ... | 1981 | 6269731 |
| evidence of separate pathways for viral and chemical carcinogenesis in c3h/stwi mouse mammary glands. | | 1980 | 6270008 |
| lack of induction of murine mammary tumor virus expression in cultured mammary glands treated with chemical carcinogens. | | 1981 | 6270025 |
| quantitative of murine mammary tumor virus-related rna in mammary tissues of low- and high-mammary-tumor-incidence mouse strains. | lactating mammary glands and hormonally induced mammary tumors of balb/c mice from three geographically separated breeding colonies were examined by molecular hybridization, using murine mammary tumor virus (mumtv) cdna representing the entire viral genome to determine the amount of mumtv-related rna expressed in these tissues. the rna extracted from these tissues by the classical sodium dodecyl sulfate-pronase, phenol-chloroform procedure (method 1) contained barely detectable levels of mumtv-r ... | 1981 | 6270387 |
| [possible participation of endogenous mmtv virus in chemical carcinogenesis of mouse mammary glands]. | a study was made of the effect of immunization with formalinized mmtv on mammary tumor incidence in balb/c mice exposed to dimethylbenzanthracene. in mice immunized with mmtv, the incidence of mammary tumours was significantly lower and the latent period longer as compared with the control group immunized with mulv. the indirect fixed immunofluorescence technique has shown that tumour cells in both groups express gp52 and p27 antigens. the possible involvement of endogenous mmtv into chemical ca ... | 1981 | 6271307 |
| possible role of genetic cell variants in the viral induction of mouse mammary tumors. | out of three attempts to induce neoplasia in normal c57bl mammary epithelial cells with the mouse mammary tumor virus (mumtv) only one presented signs of tumorigenicity. immunofluorescence showed that virus synthesis took place in all three sublines but tumorigenicity as detected by cell aggregation viability (cav) and transplantation into syngeneic mice failed to occur in two of them. by comparison, cells from a balb/c spontaneous mammary tumor that do not express mumtv were 100% tumorigenic, w ... | 1981 | 6271665 |
| estimation of mouse mammary tumor virus gp52 abundance by protein a assay: a comparison of viral antigen expression on c3h and gr mammary tumor cells. | an adherent cell isotopic staphylococcal protein a test (ispat) was used to estimate the abundance of mouse mammary tumor virus (mmtv) gp52 cell surface antigen (csa)on mammary tumor cells. protein a assays were first utilized, not strictly as a means of antigen detection, but as a means to determine the kinetics of dexamethasone-mediated changes in gp52 cell surface expression. results indicated increases in gp52 csa within 4 h of dexamethasone treatment and maximal levels of antigen expression ... | 1981 | 6271704 |
| glucocorticoids regulate expression of dihydrofolate reductase cdna in mouse mammary tumour virus chimaeric plasmids. | fusions between the mouse mammary tumour virus long terminal repeat and a mouse dihydrofolate reductase cdna have been constructed in a sv40 vector. when these plasmids are transferred into recipient cells, the production of dihydrofolate reductase is regulated by glucocorticoid hormones. these results define a hormonally responsive region of the viral genome. | 1981 | 6272123 |
| activation of related transforming genes in mouse and human mammary carcinomas. | high molecular weight dnas of five tumors induced by mouse mammary tumor virus (mmtv), two mouse mammary tumors induced by a chemical carcinogen, and one human mammary tumor cell line (mcf-7) were assayed for the presence of transmissible activated transforming genes by transfection of nih 3t3 mouse cells. dnas of all five mmtv-induced tumors, one chemical carcinogen-induced tumor, and the human tumor cell line induced transformation with high efficiencies (approximately 0.2 transformant per mic ... | 1981 | 6272293 |
| absence of antigens related to murine mammary tumour virus polypeptides in rat mammary tumours. | | 1981 | 6273175 |
| age- and sex-related differences in antibody formation and blastogenic responsiveness of splenocytes from riii mice developing virus-induced mammary adenocarcinoma. | inbred riii mice, known to be infected neonatally with murine mammary tumor virus so that females develop mammary adenocarcinoma by 12-15 months of age, were examined with regard to antisheep red blood cell antibody responses at the cellular level. female mice, 3-11 months old, compared to male mice of the same ages had consistent and significant depression of the antibody response of their splenocytes. furthermore, female mice with adenocarcinoma showed an even greater depression of the antibod ... | 1981 | 6273637 |
| the endogenous proviral mouse mammary tumor virus genes of the gr mouse are not identical and only one corresponds to the exogenous virus. | the endogenous proviral copies of mouse mammary tumor virus (mmtv) were selected from a gene library of gr mouse dna. we obtained five different lambda. mmtv recombinant clones. four of them correspond to the 3' eco ri fragments of the endogenous proviruses an one comprises an intact mmtv provirus with 2 to 3 kb of flanking mouse genomic dna. heteroduplex formation followed by s1 digestion under stringent conditions shows that there is nucleotide sequence heterology among the cloned endogenous p ... | 1981 | 6273791 |
| purified glucocorticoid receptors bind selectively in vitro to a cloned dna fragment whose transcription is regulated by glucocorticoids in vivo. | activated glucocorticoid receptor protein, purified to 40-60% homogeneity from rat liver extracts, binds selectively in vitro to a cloned fragment of murine mammary tumor virus (mtv) dna. the dna fragment tested contains about half of the sequences present in intact mtv dna, and its rate of transcription, like that of the intact viral element, is strongly stimulated by glucocorticoids when it is introduced into the genome of a receptor-containing cell. in contrast, the receptor fails to bind sel ... | 1981 | 6273877 |
| is there any diagnostic relevance of human antibodies which react with mouse mammary tumor virus (mumtv)? | applying an indirect immunofluorescence assay with prolonged serum incubation on frozen-cut mouse mammary tumor slices, antibodies are detectable in human sera which react with viral inclusion bodies consisting of intracytoplasmic a particles (iap). these iap are known to represent intracellular entities of the mouse mammary tumor virus (mumtv), mainly related to mumtv core constituents. in 1,449 women studied, the antibody incidence is partially correlated with proliferating changes of the mamm ... | 1981 | 6274270 |
| diagnosis of primary breast carcinoma through immunohistochemical detection of antigen related to mouse mammary tumor virus in metastatic lesions: a report of two cases. | recent investigations have established that approximately half of human breast carcinomas contain an immunohistochemically detectable antigen which is cross-reactive with the 52000-dalton major glycoprotein (gp52) of the mouse mammary tumor virus (mmtv). this antigen can be localized in paraffin-embedded sections of routinely fixed tissues using heterologous antibodies to gp52 or mmtv. this report describes two patients with metastatic carcinoma in axillary lymph nodes without any clinical evide ... | 1982 | 6274506 |
| strain difference in the expression of mammary tumor virus antigen in the male genital organs of mice during aging. | mammary tumor virus (mtv) antigen expression was tested in the male genital organs (testis, epididymis, prostate, seminal vesicle and coagulating gland) of dd/tbr, kf and ddd strains (dd (german) mouse group), gr strain (swiss origin), shn and sln strains (different swiss origin), c3h and a strains (american origin), balb/c and c57bl strains (low mammary tumor strains), and ddf and shnf strains (mtv eliminated strains). microimmunodiffusion analysis showed that expression of mtv antigen is tissu ... | 1981 | 6274726 |
| covert infection of a mouse mammary tumor cell line with mycoplasma hyorhinis: cosedimentation with mouse mammary tumor virus in sucrose density gradients. | supernatant fluids from cultures of a mouse mammary tumor (mt) cell line were found to produce a specific cell detachment effect when inoculated into hela cells. the cell detachment factor (cdg) responsible for this effect was examined. repeated attempts to cultivate this cdf in bacteriologic, fungal, and mycoplasma media were unsuccessful. however, using the dna fluorochrome staining technique and specific immunofluorescent staining procedures, the cdf was identified positively as a noncultivab ... | 1981 | 6274789 |
| enhanced immune reactivity to hepatoma 22a cells in mtv-infected compared with mtv-free c3h mice. | the transplantability and growth rate of mouse mammary and non-mammary tumours (sarcoma and hepatoma) were compared in mtv-free (mtv-) and mtv-infected (mtv+) c3h mice. it was demonstrated that sarcoma and hepatoma, in contrast to mammary tumours, grew better in mtv- mice. the difference between c3h sublines in the growth of hepatoma transplants was found to be determined by the stronger specific immune response and higher natural lymph node cell cytotoxicity in mtv+ mice. | 1981 | 6274791 |
| dexamethasone induction of the intracellular rnas of mouse mammary tumor virus. | we have studied the kinetics of dexamethasone induction of mouse mammary tumor virus (mmtv) rnas and proteins in virus-infected rat xc cells and gr mouse mammary tumor cells. a detectable increase in viral rna in infected xc cells was present within 10 min after hormone addition, and half-maximal induction was achieved in less than 2 h. the increase in viral rna concentration was apparent first in nuclear rna and later in the cytoplasm. within the first 15 min of induction, only genome-sized rna ... | 1981 | 6275112 |
| genetic mapping of endogenous mouse mammary tumor viruses: locus characterization, segregation, and chromosomal distribution. | the restriction endonuclease ecori has been used to study the inheritance of strain difference in endogenous mouse mammary tumor virus dna sequences. this enzyme, which cleaves at only one site within the nondefective viral genome, generates dna fragments containing mouse mammary tumor virus sequences which vary in size according to the locations of ecori restriction sites in the flanking mouse sequences, thereby defining unique integration sites of the viral genome. recombinant inbred strains o ... | 1981 | 6275115 |
| expression of the murine mammary tumor virus in the milk of f1 hybrids of virus negative mouse strains. | | 1981 | 6276182 |
| the presence of b type virions in trichoepithelioma of a mouse. | | 1981 | 6276609 |
| altered methylation of endogenous viral promoter sequences during mammary carcinogenesis. | | 1982 | 6276763 |
| long terminal repeats of endogenous mouse mammary tumour virus contain a long open reading frame which extends into adjacent sequences. | | 1982 | 6276778 |
| use of an electroimmunodiffusion method on cellulose acetate films for the detection of antigenicity in human breast cancers that is related to the major core antigen of mouse mammary tumor virus (mumtv). | a highly sensitive electroimmunodiffusion method on cellulose acetate films, developed by abelev on the basis of isotachoelectrophoresis, was applied to search of mumtv-related antigenicity in tumor tissue and sera of breast cancer patients. in 2 out of 5 breast cancer extracts, protein fractions corresponding to a molecular weight of about 50,000 daltons were seen to exhibit antigenicity related to the major core antigen of mumtv (p27). this antigenicity could not be detected in the sera of the ... | 1981 | 6277267 |
| mammary tumor virus dna as a marker for genotypic variance within hormone-responsive gr mouse mammary tumors. | mammary tumors of gr mice acquire extra mammary tumor virus (mmtv) dna information within their dna during tumor growth and development. these extra mmtv genes have been used by us as genotypic markers to investigate the heterogeneity of gr mammary tumors and their loss of hormone dependence during serial transplantation. our studies reveal that the various subpopulations of cells within individual gr mammary tumors are characterized by differences in number and location of acquired extra mmtv d ... | 1982 | 6277477 |
| glucocorticoid regulation of the ha-musv p21 gene conferred by sequences from mouse mammary tumor virus. | molecular chimeras with the p21 transforming gene of harvey murine sarcoma virus linked to dna containing the long terminal repeat (ltr) or mouse mammary tumor virus (mmtv) have been constructed. transformants of nih 3t3 cells induced by transfection with mmtv ltr-p21 hybrid dna have been identified that express the normal p21 gene product. the levels of p21 rna and protein in these transformants are regulated by physiological concentrations of dexamethasone, a synthetic glucocorticoid hormone. ... | 1981 | 6277498 |
| mammary tumor virus dna contains sequences required for its hormone-regulated transcription. | glucocorticoids regulate the rate of transcription of integrated murine mammary tumor virus (mtv) genes in most clones of mtv-infected rat hepatoma tissue culture (htc) cells. to determine whether hormonal regulation is mediated from flanking cellular sequences or rather from within the viral dna, we analyzed the relative rates of transcription of mtv and adjacent htc sequences in two lines of infected htc cells, j2.15 and j2.17, each of which contains a single insertion of mtv dna. in addition, ... | 1981 | 6277499 |
| structure, stability, methylation, expression and glucocorticoid induction of endogenous and transfected proviral genes of mouse mammary tumor virus in mouse fibroblasts. | a sequence of mouse genomic dna containing an endogenous mouse mammary tumor virus (mmtv) provirus, which was isolated by molecular cloning in lambda vector phage, has been reintroduced into cultured mouse l cells, using the thymidine-kinase cotransfection technique. individual cell clones that acquired the transfected mmtv proviral dna have been isolated. the transfected dna remains stable in these cells and does not become methylated. it is transcribed into mmtv rna, and the transcription is s ... | 1981 | 6277735 |
| independence of h-2 and viral antigens on the cell surface and absence of h-2 antigens on murine leukemia virus and mouse mammary tumor virus particles. | by indirect immunoelectron microscopy we tested for the presence of h-2 antigens on murine mammary tumor virus (mmtv) and murine leukemia virus (mulv) particles. the association of h-2 antigens and viral antigens on the virus-infected cell surface was investigated with antibody-induced redistribution. mammary tumor cells and leukemia cell lines with different h-2 genotypes and carrying different mumtv or mulv were used. no h-2 antigens could be demonstrated on the envelope of mmtv and mulv parti ... | 1981 | 6277784 |
| natural cell-mediated immunity to mouse mammary tumor virus and its relevance to host immune defences. | | 1981 | 6279022 |
| organization of proviral dna and protein composition of hormonally stimulated c57bl/10 strain-associated mouse mammary tumor virus. | two continuous lines, bl-matu/a1 and bl-matu/s6, were established from c57bl/10 mammary adenocarcinomas induced by dmba-prolactin-estradiol treatment. under in vivo stimulation with dexamethasone, insulin, prolactin, and prostaglandin a1, the cells produce detectable amounts of b-type particles with biochemical properties similar to the gr-mumtv. analysis of restriction endonuclease-generated fragments of cellular dna revealed identical patterns in the integration sites and internal recognition ... | 1981 | 6280079 |
| [hormone-dependent process of the maturation of the major structural proteins of the mouse mammary tumor virus]. | the following findings were obtained by the radio-immunoprecipitation method with antisera to gp52 and p27. when the cells were cultivated in a hormone-free medium, they contained precursors of proteins of gene gag (pr 73gag) and gene evn (gpr 70env). no mature structural mtv proteins were found. the addition of insulin to the growth medium had no effect on maturation of protein precursors. when dexamethazone was added to the medium, gpr 70env "maturated" to gp52 of the main envelope glycoprotei ... | 1982 | 6280389 |
| radioimmunolocalization of murine mammary tumor virus proteins in gels. | | 1982 | 6280511 |
| abrogation of infectivity of mouse mammary tumor virus by reserpine. | | 1982 | 6281054 |
| earlier appearance of murine mammary tumor virus-associated antigens in duct-alveolus nodules induced by transplantation of fetal salivary mesenchyme into c3h mouse mammary glands. | mammary epithelium of adult c3h mice in contact with fetal salivary mesenchyme took morphogenetically a salivary gland-like pattern of growth and developed a hyperplastic nodular mass at the site of transplantation. when murine mammary tumor virus-bearing c3h mice were treated in this way, early development and high incidence of mammary cancer were observed from these nodules compared to unstimulated mammary glands of the same host. since tumor development, the viral antigens in these hyperplast ... | 1981 | 6281120 |
| role of natural prostaglandins in the control of murine mammary tumor virus expression. | the regulation of murine mammary tumor virus (mumtv) production by mammotropic hormones, hormonomimetic substances, and cyclic nucleotides was investigated. the virus produced in control and treated mammary tumor cell cultures was quantitated by measuring the supernatant reverse transcriptase activity in exogenous reaction using poly(rc).oligo(dg) as template-primer. two days after exposure, the synthetic glucocorticoid, dexamethasone (dxmt), increased spontaneous mumtv production at optimal con ... | 1982 | 6281284 |