| persistent papillomatosis associated with immunodeficiency. | a case report of a young bull with persistent papillomatosis associated with immunodeficiency is presented. humoral immune responses were normal but cell mediated immunity was deficient. the possible significance of the findings to pathogenesis and therapy of the disease is discussed. | 1975 | 165037 |
| [induction of cutaneous or subcutaneous fibroblastic tumors in the afghan pika (ochotona rufescens rufescens) by injection or bovine papilloma virus]. | newborn afghan pikas have been inoculated with bovine papilloma virus via the subcutaneous route. cutaneous or subcutaneous fibromas and fibrosarcomas were observed after a mean incubation period of nine months. the transmission of these tumors by homograft has been obtained. bovine papilloma virus antibodies have been demonstrated in most of the animals inoculated at birth. they have not been detected in animals bearing transplanted tumors. | 1975 | 168982 |
| [bovine viruses and methods for their detection]. | | 1975 | 169627 |
| quantitation of bovine papilloma viral dna in viral-induced tumors. | bovine papilloma virus (bpv) dna was labeled in vitro under conditions of repair synthesis and subsequently used as a "probe" in dna-dna reassociation studies to detect bpv-specific dna sequences in a viral-induced calf meningioma and hamster fibroma. in vitro labeled bpv dna had denaturation characteristics expected for duplex dna and denatured dna reassociated with apparent second-order kinetics. analysis of in vitro labeled bpv dna reassociation rates in the presence of excess tumor dna revea ... | 1976 | 176447 |
| precipitin response of cattle to commercial wart vaccine. | fifty young bulls were given commercial wart vaccine upon their arrival at a bull stud establishment. the bulls were given 2 additional vaccinations 2 and 24 weeks later. the precipitin antibody response of these bulls to bovine papilloma virus was monitored. antibody levels increased significantly, particularly after the 3rd vaccination was given at 24 weeks, but decreased markedly within 20 weeks after the last vaccination was given. these results demonstrated that formalin-inactivated bovine ... | 1976 | 178253 |
| chromatin-like structures obtained after alkaline disruption of bovine and human papillomaviruses. | four low-molecular-weight polypeptides migrating like h2a, h2b, h3, and h4 calf liver histones were detected by sodium dodecyl sulfate-acrylamide gel electrophoresis of highly purified preparations of bovine papillomavirus (bpv) and human papillomavirus (hpv). complexes of these polypeptides and viral dna were isolated by agarose-gel filtration of the alkaline disruption products of both viruses. when observed under the electron microscope, these complexes appeared as circular structures compose ... | 1977 | 191643 |
| bovine papilloma virus: presence of virus-specific dna sequences in naturally occurring equine tumors. | four of five spontaneous benign equine connective tissue tumors of unknown etiology and a bovine papilloma virus (bpv)-induced equine tumor contained bpv-specific dna sequences as determined by dna-dna hybridization of dna from tumors with bpv dna labeled in vitro. analysis of the kinetics of reassociation indicated that 20-75% of the bpv genome was present in the various tumors. the number of partial bpv genome equivalents ranged from 60 to 500 copies per diploid quantity of cellular dna. therm ... | 1977 | 191813 |
| the occurrence of human wart-virus antibodies in dogs, pigs and cattle. | using the immunodiffusion method, antibodies against human wart-virus were detected in dog, pig and cattle sera but not in horse and reindeer sera. antibodies were found in 25 percent (28/114) of the dog sera, the prevalence of antibodies being fairly similar to that in children of the same age. by electron microscopy the antibodies in dog sera were shown to attach to and precipitate the human wart-virus particles, and in immunodiffusion the precipitation lines of human and dog sera were shown t ... | 1978 | 210743 |
| demonstration of two distinct classes of bovine papilloma virus. | | 1978 | 213876 |
| common membrane neoantigens on bovine papilloma virus-induced fibroma cells from cattle and horses. | cultured cells from bovine papilloma virus (bpv)-induced fibroblastic tumors and normal dermis of cattle, horses, and hamsters were examined for cell membrane or internal neoantigens, using the indirect immunofluorescence technique. sera from cattle and horses bearing bpv-induced fibromas cross reacted with cell membranes of tumor, but not with normal dermal cells of both species. the reaction could be blocked with homologous, but not heterologous, serum of these 2 species. immunofluorescence wa ... | 1978 | 213996 |
| hybridization of bovine papilloma virus type 1 and type 2 dna to dna from virus-induced hamster tumors and naturally occurring equine tumors. | dnas from bovine papilloma virus(bpv)-induced hamster tumors and from equine connective tissue tumors of unknown etiology were examined for bpv dna sequences by molecular hybridization. dna from two distinct classes of bpv (type 1 and type 2) was labeled in vitro and used as probes. analysis of dna-dna reassociation kinetics indicated that both virus types were capable of tumor induction in the hamster. dna isolated from 6 of 7 equine tumors accelerated the reassociation of the bpv dna probes. b ... | 1979 | 218902 |
| seroepidemiologic studies of bovine papillomavirus infections. | bovine and human sera were analyzed for the presence of antibodies against bovine papillomavirus types 1 and 2 (bpv 1 and 2) and human papillomavirus type 1 (hpv 1) in a solid-phase radioimmunoassay. human sera did not react with bpv antigens, and bovine sera showed no evidence of antibodies against hpv 1. in contrast, 19% of all bovine sera tested reacted with bpv 1 and 2 antigens, and 35% of human sera revealed antibodies against hpv 1. no serologic evidence was obtained for heterologous infec ... | 1979 | 220453 |
| a survey of bovine teat papillomatosis. | | 1979 | 222039 |
| partial characterization of a new type of bovine papilloma viruses. | | 1979 | 223295 |
| in vitro transformation by bovine papilloma virus. | this paper reports the development of a quantal transformation assay for bovine papillome virus. support for its specificity to fibropapilloma derived bovine papilloma virus comes from (i) the absence of transformation associated changes following inoculations of normal bovine skin, bovine teat papilloma, bovine teat focal epithelial hyperplasia lesion and canine papilloma derived suspensions; (2) in vitro transformation occurs when cscl purified fibropapilloma-derived bpv is used; (3) in vitro ... | 1979 | 225431 |
| physical maps of bovine papillomavirus type 1 and type 2 genomes. | physical maps of bovine papillomavirus type 1 and type 2 (bpv-1 and bpv-2) dna were constructed from analysis of the electrophoretic mobilities of restriction endonuclease cleavage fragments from dual digests. bpv-1 dna was sensitive to hind iii, hindiii, ecori, hpai, and bamhi, with all but hindii yielding single scissions. bpv-2 dna was resistant to ecori, and hindiii had one cleavage site whereas hpai, bamhi, and hindii yielded multiple fragments. of four bpv-1 isolates examined, dna from one ... | 1979 | 228086 |
| conserved polynucleotide sequences among the genomes of papillomaviruses. | the dnas of different members of the papillomavirus genus of papovaviruses were analyzed for nucleotide sequence homology. under standard hybridization conditions (tm - 28 degrees c), no homology was detectable among the genomes of human papillomavirus type 1 (hpv-1), bovine papillomavirus type 2 (bpv-2), or cottontail rabbit (shope) papillomavirus (crpv). however, under less stringent conditions (i.e., tm - 43 degrees c), stable hybrids were formed between radiolabeled dnas of crpv, bpv-1, or b ... | 1979 | 232171 |
| experimental transmission of bovine papilloma virus (bpv) extracted from morphologically distinct teat and cutaneous lesions and the effects of inoculation of bpv transformed fetal bovine cells. | bovine papilloma virus (bpv) was extracted from five cattle each affected with only one of five morphologically distinct lesion types. when inoculated into experimental calves either by scarification or intradermal injection, the bpv extracts produced lesions macroscopically and microscopically similar to those from which individual extracts were made. fetal bovine cells, transformed in vitro with bpv, failed to produce fibromas, fibropapillomas or papillomas when inoculated into experimental ca ... | 1979 | 233276 |
| partite expression of the bovine papillomavirus e1 open reading frame in escherichia coli. | six recombinants were constructed which expressed portions of the bovine papillomavirus e1 open reading frame as ompf/e1/beta-galactosidase tribrid fusion proteins in escherichia coli. rabbit sera containing e1-specific antibodies were generated against five of these six fusion proteins (which together constitute 74% of the full-length e1 open reading frame). the individual fusion proteins and their cognate antisera will be useful reagents for defining the structure and function of the bpv e1 pr ... | 1992 | 1309664 |
| amino acids necessary for dna contact and dimerization imply novel motifs in the papillomavirus e2 trans-activator. | the bovine papillomavirus e2 protein regulates viral transcription by binding as a dimer to the dna sequence accgn4cggt. the dimerization and dna-binding properties are localized within its carboxy-terminal 85 amino acids (325-410). utilizing random mutagenesis coupled with phenotypic selection in yeast, functionally important amino acids in the dna-binding domain were identified. four trans-activation defective point mutants within a short segment (amino acids 337-344) were dna binding defectiv ... | 1992 | 1309714 |
| integration of bovine papillomavirus type 1 dna and analysis of the amplified virus-cell junctions in transformed primary mouse fibroblasts. | we have analysed the site of bovine papillomavirus type 1 (bpv-1) dna integration in clones originating from a transformed primary mouse fibroblast cell line established by transfection of linear bpv-1 dna. viral dna was integrated at a single site in the host genome with an intact early region and an almost complete long control region. sequence analysis showed that the bpv-1 dna was integrated at the hindiii site (the enzyme used to linearize the bpv-1 dna for transfection) with short deletion ... | 1992 | 1309860 |
| uptake of cadmium is diminished in transfected mouse nih/3t3 cells enriched for metallothionein. | to determine the relationship between cellular uptake of cadmium and content of metallothionein, we measured uptake of 109cd in cells that differed in content of metallothionein (mt). mt cells were derived from nih/3t3 cells by transfection with a plasmid containing the genome of bovine papilloma virus and the mouse metallothionein-i gene, driven by the promotor for the glucose-regulated protein of 78 kda. control cells were similarly transfected with bovine papilloma virus-based plasmids with t ... | 1992 | 1310676 |
| human papillomavirus type 16 e5 gene stimulates the transforming activity of the epidermal growth factor receptor. | we have until recently made several unsuccessful attempts to assign any activity to the human papillomavirus type 16 (hpv-16) e5 gene product. however, studies with the bovine papilloma virus 1 (bpv-1) e5 protein indicated an interaction with the epidermal growth factor receptor (egfr). in light of the overall similarity between the hpv and bpv e5 proteins we attempted to determine whether the hpv-16 e5 gene had any common activity. in cells expressing high levels of egfr plus hpv-16 e5 we found ... | 1992 | 1311063 |
| increased calmodulin affects cell morphology and mrna levels of cytoskeletal protein genes. | we have previously described stable mouse c127 cell lines in which a cam mini-gene has been expressed in a bovine papilloma virus-based expression vector (rasmussen and means: embo j. 6:3961-3968, 1987). elevation of cam to levels five-fold higher than in control cells caused an acceleration in cell cycle progression by reducing the length of the g1 period. when these cell lines were originally isolated it was observed that cells in which cam levels were increased had a flattened morphology. in ... | 1992 | 1311642 |
| the bovine papillomavirus constitutive enhancer is essential for viral transformation, dna replication, and the maintenance of latency. | bovine papillomavirus type 1 (bpv-1) has served as the prototype papillomavirus for the study of viral transcription, dna replication, and latency. however, no cis essential transcription control regions which are necessary for both transformation and replication of bpv-1 or any other papillomavirus have yet been defined. we have found that bpv-1 mutants with deletions in the long control region were defective for transformation and replication, with the essential region in the 5' long control r ... | 1992 | 1312634 |
| reconstitution of an episomal mouse aprt gene as a consequence of recombination. | when a functional murine adenine phosphoribosyltransferase (aprt) gene linked to bovine papilloma virus (bpv) dna is transfected into aprt- l cells, the cells are rendered aprt+ and the aprt gene persists as an episome. cotransfection with two bpv vectors, one containing the 5' half of the aprt gene and the other the 3' half of the gene, that share about 300 bp of common sequence in intron 2, produces aprt+ cells with functional aprt as an episome. southern blot analysis of low molecular weight ... | 1992 | 1313148 |
| mechanism of action of the papillomavirus e2 repressor: repression in the absence of dna binding. | repression of papillomavirus e2-dependent gene expression was studied by using transient transfections into mouse embryo fibroblast cells. cotransfection of a gene corresponding to the naturally occurring repressor e2-tr along with the full-length e2 gene resulted in up to 98% repression of e2-dependent reporter gene expression. a series of e2 dna-binding domain mutants were transferred into the e2-tr form and characterized for their ability to repress e2-dependent transactivation. all mutants w ... | 1992 | 1316493 |
| inhibition of bovine papillomavirus plasmid dna replication by adeno-associated virus. | the helper-dependent human parvovirus adeno-associated virus type 2 (aav) inhibits both the oncogenic transforming abilities and the dna replication of its helper viruses, adenovirus (ad), and herpes simplex virus (hsv). as aav-2 also inhibits the transforming ability of bovine papillomavirus type 1 (bpv), aav-2 was assayed for its ability to inhibit bpv plasmid dna replication. here we find that the aav-2 rep78 gene is able to trans-inhibit bpv plasmid dna replication and that the aav-2 termina ... | 1992 | 1318608 |
| early promoters of genital and cutaneous human papillomaviruses are differentially regulated by the bovine papillomavirus type 1 e2 gene product. | the physical state of the human papillomavirus (hpv) genome is usually different in malignant lesions of the skin, in which it is generally found in episomal form, and genital mucosa, in which it is frequently integrated with disruption of the e2 gene. using chimeric or natural hpv promoters in the presence of the bovine papillomavirus type 1 e2 gene product, we observed transcription activation or repression, depending on the distance of e2-binding motifs from the start site. we found a clear d ... | 1992 | 1318941 |
| bovine papillomavirus type 1-transformed primary mouse fibroblasts show no correlation between tumorigenicity and viral gene expression, but c-myc gene expression is elevated in tumorigenic cell lines. | bovine papillomavirus type 1 (bpv-1)-transformed primary mouse fibroblasts containing episomal or integrated bpv-1 sequences were analysed for virus-specific transcripts and c-myc gene expression. total bpv-1-specific expression was high in cell lines containing episomal bpv-1 dna in comparison to lines containing integrated bpv-1 sequences, mainly due to higher expression of the e6/e7 sequences. no correlation was found between the viral transcription and tumorigenicity, although bpv-1 gene exp ... | 1992 | 1318945 |
| localization of bovine papillomavirus type 1 e5 protein to transformed basal keratinocytes and permissive differentiated cells in fibropapilloma tissue. | we examined expression of the e5 transforming protein of bovine papillomavirus type 1 (bpv-1) in naturally and experimentally infected bovine cells. bovine conjunctival fibroblasts transformed in vitro by experimental infection with purified bpv-1 virions expressed significantly higher amounts of the 7-kda e5 protein than bpv-1-transformed murine c127 cells. indirect immunofluourescence analysis revealed a cytoplasmic, predominantly juxtanuclear, localization of e5 protein in the in vitro virus- ... | 1992 | 1319069 |
| papillomavirus associated skin lesions in a cat seropositive for feline immunodeficiency virus. | a cat was presented with skin lesions consisting of slightly raised pigmented plaques, 2-7 mm in diameter with a rough slightly verrucous surface. histologically these lesions were identified as papillomas. a papillomavirus infection was demonstrated: virus-like particles were present in the nuclei of cells within the lesions, and staining with an anti-bovine papillomavirus (bpv-1) antibody was obtained. an infection with feline immunodeficiency virus was diagnosed in this cat; this condition ha ... | 1992 | 1320786 |
| identification and genetic definition of a bovine papillomavirus type 1 e7 protein and absence of a low-copy-number phenotype exhibited by e5, e6, or e7 viral mutants. | the bovine papillomavirus type 1 (bpv-1) genome replicates as a multiple-copy plasmid in murine c127 cells transformed to neoplasia by virus infection or by transfection with bpv-1 dna. it was reported previously that bpv-1 genomes harboring frameshift mutations in the e6 or e7 open reading frame (orf) replicated in c127 cells transformed by these mutants at a low copy number. furthermore, the characterization of a bpv-1 mrna in which the e6 and e7 orfs were spliced together in frame has led to ... | 1992 | 1321280 |
| viral e1 and e2 proteins support replication of homologous and heterologous papillomaviral origins. | we have shown that e1 and e2 proteins of human papillomavirus type 11 (hpv-11) were essential to support the replication of the homologous viral origin (ori) in a transient replication assay, similar to reports on bovine papillomavirus type 1 (bpv-1). unexpectedly, matched or even mixed combinations of e1 and e2 proteins from hpv-11 or bpv-1 replicated either ori in human, monkey, and rodent cell lines of epithelial or fibroblastic lineage, albeit with varied efficiencies. either set of viral pr ... | 1992 | 1321423 |
| effect of interferon gamma on the sensitivity of bovine-papilloma-virus(bpv1)-transformed cell lines to cell-mediated cytotoxicity. | the effect of interferon gamma (ifn gamma) on the immunogenicity and immunosensitivity of mouse cell lines transformed by bovine papillomavirus type 1 (bpv1) dna was examined in a syngeneic mouse model. the overnight incubation of bpv1-transformed cell lines with 100 iu/ml ifn gamma did not affect their ability to induce the generation of cytotoxic effector cells but it clearly increased their sensitivity to lysis by interleukin-2-induced lymphokine-activated killer (lak) cells and by non-specif ... | 1992 | 1322243 |
| stable association between the bovine papillomavirus e5 transforming protein and activated platelet-derived growth factor receptor in transformed mouse cells. | the 44-amino acid e5 transforming protein of bovine papillomavirus is the shortest protein known to induce tumorigenic transformation of fibroblasts. we showed previously that expression of the e5 protein activates the cellular beta receptor for platelet-derived growth factor (pdgf) and proposed that the activated receptor transmits the transforming signal to the cell. here we use coimmunoprecipitation analysis to show that the e5 protein and the activated pdgf receptor exist in a stable complex ... | 1992 | 1323117 |
| control of human papillomavirus type 11 origin of replication by the e2 family of transcription regulatory proteins. | replication of human papillomavirus type 11 (hpv-11) dna requires the full-length viral e1 and e2 proteins (c.-m. chiang, m. ustav, a. stenlund, t. f. ho, t. r. broker, and l. t. chow, proc. natl. acad. sci. usa 89:5799-5803, 1992). using transient transfection of subgenomic hpv dna into hamster cho and human 293 cells, we have localized an origin of replication (ori) to an 80-bp segment in the upstream regulatory region spanning nucleotide 1. it overlaps the e6 promoter region and contains a sh ... | 1992 | 1323690 |
| transcription of bpv-1 genes in transfected f9 cells. | in f9 cells transformed with bovine papillomavirus type 1 (bpv-1) sequences two different phenotypes can be recognized. one cell type shows the characteristics of the parental stem cell line, whereas the other comprises cells with spindle-like morphology that do not adhere to each other, similar to retinoic acid-treated f9 embryonal carcinoma cells. the phenotypically altered cells plate more efficiently than the stem cells, grow well in soft agar and show an extended lifespan in the differentia ... | 1992 | 1323821 |
| conserved cysteine residue in the dna-binding domain of the bovine papillomavirus type 1 e2 protein confers redox regulation of the dna-binding activity in vitro. | the bovine papillomavirus type 1 e2 open reading frame encodes three proteins involved in viral dna replication and transcriptional regulation. these polypeptides share a carboxyl-terminal domain with a specific dna-binding activity; through this domain the e2 polypeptides form dimers. in this study, we demonstrate the inhibition of e2 dna binding in vitro by reagents that oxidize or otherwise chemically modify the free sulfhydryl groups of reactive cysteine residues. however, these reagents had ... | 1992 | 1323841 |
| synergism between bovine papillomavirus type 4 and the flavonoid quercetin in cell transformation in vitro. | bovine papillomavirus type 4 (bpv-4) morphologically transforms primary bovine cells in vitro only in the presence of an activated ras gene. the transformed cells are capable of anchorage-independent growth, but are not immortal and are incapable of inducing tumors in nude mice, suggesting that other events are needed to convert the cells to the fully transformed phenotype. we show here that treatment of the cells with a single dose of the flavonoid quercetin leads to full oncogenic transformati ... | 1992 | 1325710 |
| two cellular single-strand-specific dna-binding proteins interact with two regions of the bovine papillomavirus type 1 genome, including the origin of dna replication. | we have identified and purified to near homogeneity two specific single-stranded dna-binding factors (spsf i and ii) with molecular masses of 42 and 39 kda, respectively, from calf thymus. gel retention analysis and competition experiments demonstrate that the ubiquitous proteins spsf i and ii specifically interact with single-stranded dna derived from the minimal in vitro origin of replication of bovine papillomavirus type 1 and a region of the viral genome proposed to be involved in plasmid ma ... | 1992 | 1326653 |
| mammalian and viral dna sequences which interfere with the maintenance of a centromeric vector in yeast. | we constructed a recombinant plasmid by inserting into the prs314 yeast centromeric plasmid vector the mouse dna sequence responsible for the maintenance in transgenic mice of plasmid p12b1 (1). such constructs could constitute convenient shuttle vectors between yeast and mouse cells. however, the recombinant molecule could not be established as a stable plasmid in saccharomyces cerevisiae. a region with a limited similarity to the yeast centromere (cen element) is present in this mouse sequence ... | 1992 | 1326955 |
| separation of the transcriptional activation and replication functions of the bovine papillomavirus-1 e2 protein. | replication of bovine papillomavirus-1 (bpv-1) dna requires two viral gene products, the e1 protein and the full-length e2 protein. the 48 kda e2 protein is a site-specific dna-binding protein that binds to several sites which lie adjacent to the bpv-1 origin of replication. the 85 amino acid c-terminal domain contains the specific dna binding and dimerization properties of the protein. the approximately 200 amino acid n-terminal domain is crucial for transcriptional activation. both of these do ... | 1992 | 1327758 |
| replication of bovine papillomavirus vectors in murine cells. | varying capacities for autonomous replication have been obtained with bovine papillomavirus type 1 (bpv-1)-based expression vectors in mouse c127 cells. both integration of the vector dna into the genome of the host cell and replication as monomeric extrachromosomal elements have been observed. in this study, we have examined what features of bpv-1 vectors influence their replication potential. transfection of the entire bpv-1 genome into c127 cells resulted in the replication of extrachromosoma ... | 1992 | 1327973 |
| evidence that the transcriptional trans-activating function of the bovine papillomavirus type 1 e2 gene is not required for viral dna amplification in division-arrested cells. | amplification of bovine papillomavirus type 1 (bpv-1) dna in growth-arrested mouse cell cultures appears to mimic the process of induction of vegetative bpv-1 dna synthesis in cells of the stratum spinosum in productively infected bovine warts. in both cases, cells permissive for viral dna amplification express large amounts of viral e2 protein which accumulates within the cell nucleus. whereas in latently infected virus-transformed cells truncated transcriptional repressor forms of e2 predomina ... | 1992 | 1328476 |
| crystal structure at 1.7 a of the bovine papillomavirus-1 e2 dna-binding domain bound to its dna target. | the dominant transcriptional regulator of the papillomaviruses, e2, binds to its specific dna target through a previously unobserved dimeric antiparallel beta-barrel. the dna is severely but smoothly bent over the barrel by the interaction of successive major grooves with a pair of symmetrically disposed alpha-helices. the specific interface is an 'interwoven' network of interactions where the identifying base pairs of the target contact more than one amino-acid side chain and the discriminating ... | 1992 | 1328886 |
| the spermicide nonoxynol-9 does not inactivate papillomavirus. | vaginal spermicides are effective contraceptive, and are also capable of inactivating many sexually transmitted pathogens by their detergent effect on bacterial cell membranes and viral envelopes. a 5% concentration of nonoxynol-9, the most frequently used active ingredient of spermicides, was tested for its ability to reduce the transforming activity of bovine papillomavirus type 1 (bpv-1), and the infectivity of bk virus (bkv) and cytomegalovirus (cmv). nonoxynol-9 markedly reduced the infecti ... | 1992 | 1329236 |
| search for bovine papilloma virus dna in bovine ocular squamous cell carcinomas (boscc) and boscc-derived cell lines. | although the cause of bovine ocular squamous cell carcinoma (boscc) is attributed to viruses in addition to cofactors (eg, uv light), to our knowledge, the final causative agent has not been described. bovine papilloma virus (bpv)-like particles were detected in approximately 33% of various putative precursor lesions of boscc. in contrast, it was reported that, using bpv-specific antibodies, it was not possible to detect viral antigens in boscc. fourteen established boscc and 9 boscc-derived cel ... | 1992 | 1329585 |
| the induction of il-6 and gelatinase b by il-1 in mouse cell lines transformed with bovine papillomavirus: decreased production in tumorigenic cells. | six cell lines, that were cloned from murine c127 cells infected by bovine papillomavirus type 1 (bpv1), were found to differ in the degree of transformation in vitro and of tumorigenicity in vivo. in these cell lines the degree of tumorigenicity was inversely correlated with il-6 induction by il-1 beta. whereas the parental c127 cell line produced 15-30 u/ml of il-6 spontaneously, none of the transformed cell lines produced significant levels of il-6 constitutively. on induction by human il-1 b ... | 1992 | 1330001 |
| random-choice replication of extrachromosomal bovine papillomavirus (bpv) molecules in heterogeneous, clonally derived bpv-infected cell lines. | using fluorescence in situ hybridization and southern blot analysis, we show that three clonally derived cell lines transformed with bovine papillomavirus (bpv), including id13, the cell line commonly employed for bpv replication studies, are heterogeneous populations having extensive cell-to-cell variation in both the distribution and amount of bpv dna. different subclones of id13 were found to differ in the form and amount of bpv dna they contain. most subclones showed no detectable bpv sequen ... | 1992 | 1331505 |
| a constitutive enhancer in the bovine papillomavirus upstream regulatory region shares genetic elements with the viral p1 promoter. | the bovine papillomavirus upstream regulatory region represents a common element in the regulation of transcription from the five early viral promoters. we have determined the sequences required for transcription from the viral p1 promoter, which is located at the 5' end of the upstream regulatory region. in vitro transcription from p1 requires a 123-bp fragment (nucleotides 7153 to 7275; -33 to +90) consisting of an upstream tata-like sequence as well as an unidentified protein which binds to s ... | 1992 | 1331522 |
| glucocorticoid modulation of transformed cell proliferation is oncogene specific and correlates with effects on c-myc levels. | in the presence of the glucocorticoid hormone dexamethasone, bovine papillomavirus-1 (bpv-1)-transformed c127 mouse fibroblasts assume a flattened morphology and reach a saturation density of only 50% of that attained without hormone. this phenotypic reversion of transformation is dependent on the continued presence of dexamethasone and occurs with concentrations as low as 1 nm. dexamethasone also suppresses the growth of the parental c127 cells as well as that of cells transformed by polyoma mi ... | 1992 | 1331773 |
| purification and characterization of epstein-barr virus gp340/220 produced by a bovine papillomavirus virus expression vector system. | our initial results with a bovine papilloma virus (bpv) vector expression system indicated that we could produce significant amounts of epstein-barr virus (ebv) gp340/220 in the supernatant of a mouse fibroblast cell line. we have now extended these findings to show that the truncated version of gp340/220, where the membrane anchor sequence is deleted, is produced even after extended passage of the cells, at a level of approximately 1 mg/4 x 10(8) cells. a simple purification protocol using seph ... | 1992 | 1332270 |
| rolling-circle replication of a high-copy bpv-1 plasmid. | we investigated the replicating form of a bovine papillomavirus type 1 (bpv-1) deletion mutant by direct electron-microscopic analysis of low molecular weight cellular dna fractions. the detection of viral plasmid dna replication intermediates was facilitated by the isolation of a spontaneously transformed mouse cell subclone containing an unusually high viral genome copy number (approx. 1000 per cell), and by employing a slight modification of the hirt fractionation procedure to reduce the leve ... | 1992 | 1333015 |
| properties of bovine papillomavirus e1 mutants. | ostensibly comparable mutants of bovine papillomavirus type 1 (bpv-1) affecting the e1 open reading frame that were constructed in several laboratories have been reported to exhibit either reduced or increased transformation efficiencies in established mouse cell lines relative to wild-type bpv-1 dna. to resolve these discrepancies, we have reexamined many of the mutants in mouse c127 cells by using focus formation assays. our primary conclusions are that all e1 mutants tested consistently gener ... | 1992 | 1333131 |
| association of bovine papillomavirus type 2 and bracken fern with bladder cancer in cattle. | the bladder cancer syndrome that often accompanies chronic enzootic hematuria in cattle grazing on pastures infested by bracken fern has been experimentally reproduced in animals fed a diet of bracken. the experimentally induced tumors were histologically and pathologically indistinguishable from the naturally occurring ones and comprised two main types: (a) carcinoma of the urothelium identical to that seen in humans; and (b) hemangioendotheliomas of the subjacent capillaries. often the two typ ... | 1992 | 1333885 |
| the bpv-1 e5 protein, the 16 kda membrane pore-forming protein and the pdgf receptor exist in a complex that is dependent on hydrophobic transmembrane interactions. | the e5 oncoprotein of bovine papillomavirus type 1 is a 44 amino acid, highly hydrophobic protein that induces the stable transformation of immortalized murine fibroblasts, presumably through its activation of growth factor receptors. previous studies have shown that the e5 protein complexes with the 16 kda (16k) pore-forming protein of vacuolar h(+)-atpases. this integral membrane protein is essential for the acidification and function of subcellular compartments that process growth factor rece ... | 1992 | 1334459 |
| acquisition of interleukin-3 independence in fdc-p2 cells after transfection with the activated c-h-ras gene using a bovine papillomavirus-based plasmid vector. | since the ras family of proto-oncogenes is supposed to be involved in leukemogenesis by point-mutational activation, we studied the effect of the activated ras gene on the growth of a murine interleukin-3 (il-3)-dependent cell line, fdc-p2. the human activated c-h-ras gene was transfected into fdc-p2 cells by electroporation using a high-level expression vector, bmghph, which contains a partial dna sequence from bovine papillomavirus (bpv) and a hygromycin b (hmb)-resistant gene as a selectable ... | 1992 | 1334732 |
| does cruciform dna provide a recognition signal for dna-topoisomerase ii? | topoisomerase ii displays higher affinity for supercoiled dna compared to the same relaxed dna. moreover, cruciform structures are formed in topologically constrained dna. here we report that, using s1 nuclease experiments on supercoiled dna, hairpin structures are located close to numerous topoisomerase ii cleavage sites on the bpv i genome. therefore, dna secondary structure may play a role in the recognition mechanism of dna by topoisomerase ii. | 1992 | 1335757 |
| interaction with the nuclear matrix of a chimeric construct containing a replication origin and a transcription unit. | we have studied the interaction of a chimeric construct containing an origin of replication (from bovine papilloma virus) and a hormonally regulated transcription unit (long terminal repeat from the mouse mammary tumor virus, driving the v-ha-ras gene) with the nuclear scaffold and matrix from mouse fibroblasts. we used two experimental approaches because the nuclear matrix protein composition depends largely on the isolation conditions, making its definition mostly operational. in situ studies ... | 1992 | 1336395 |
| inducible expression bovine papillomavirus shuttle vectors containing ferritin translational regulatory elements. | the combination of transcriptional and translational control elements in an inducible expression vector suitable for use in stably transformed cell lines was explored. to this end, ferritin translational control elements have been inserted downstream from a mouse metallothionein (mmt-i) transcriptional promoter (pmmt-i), and upstream from various reporter protein-encoding open reading frames (orfs), all carried on a bovine papillomavirus shuttle vector. protocols which stimulate transcription (w ... | 1992 | 1336755 |
| the efficiency and timing of plasmid dna replication in xenopus eggs: correlations to the extent of prior chromatin assembly. | injection of the circular plasmid fv1 (derived from type i bovine papilloma virus) into xenopus eggs before the start of the first cell cycle dramatically increases the efficiency of plasmid replication once eggs are chemically activated. we call this the preloading effect and report kinetic and quantitative characterization of this phenomenon here. the timing and the amount of fv1 synthesis were measured by both brdutp density labelling and an optimized method of selective enzymatic digestion o ... | 1992 | 1336780 |
| comparative analysis of inositol phospholipid metabolism in viral and chemical transformation of mammalian cells. | 1. inositol phospholipid metabolites were measured from virally and chemically transformed cells. 2. increased levels of pip and pip2 were observed from both transformed cell lines as compared with controls. 3. intracellular levels of ip3 were also increased approximately three folds in bpv-1 infected id 13 cells and in 3-mc transformed nih 3t3 cells. 4. the results suggest that phosphorylation of phosphatidylinositols and enhanced generation of ip3 second messenger molecules are the common sign ... | 1992 | 1360364 |
| chemical modifications to improve uptake and bioavailability of antisense oligonucleotides. | | 1992 | 1364095 |
| growth of transformed c-127 cell in bioreactors for large-scale t-pa production. | | 1991 | 1369332 |
| the c-ha-ras oncogene induces increased expression of beta-galactoside alpha-2, 6-sialyltransferase in rat fibroblast (fr3t3) cells. | alteration in cell surface carbohydrates, and in particular cell surface sialylation, have been known to occur during oncogenic transformation. to examine the basis for such changes, we have transformed the rat fibroblast cell line fr3t3 with the oncogenes c-ha-ras ej, v-mycok10, v-src, polyoma virus middle t or the transforming bovine papilloma virus 1 (bpv1), and measured the sialytransferase activities of cellular lysates. we found that, in contrast to all other oncogenes examined, c-ha-ras i ... | 1992 | 1550989 |
| functional analysis of e2-mediated repression of the hpv18 p105 promoter. | transcription of the transforming genes e6 and e7 of the human papillomavirus type 18 (hpv18) can be repressed by the product of the e2 open reading frame. mutations were introduced in the cis-responsive elements upstream from the e6 and e7 transcriptional promoter, p105. the effect of these mutations in the absence or presence of e2 was examined in the human cervical carcinoma cell line c33, transfected with expression plasmids. in the presence of hpv18 e2, repression was relieved only when bot ... | 1991 | 1645591 |
| papillomavirus dna replication. | | 1991 | 1645776 |
| bovine papillomavirus type 1 alters the processing of host glucose- and calcium-modulated endoplasmic reticulum proteins. | we have previously characterized five proteins induced by the presence of the e2 open reading frame (orf) region of bovine papillomavirus type 1 (bpv-1) in c127 mouse fibroblasts (r. m. levenson, u. g. brinckmann, m. k. o'banion, e. j. androphy, j. t. schiller, f. tabatabai, l. p. turek, k. neary, m. t. chin, t. r. broker, l. t. chow, and d. a. young, virology 172:170-179, 1989). by specific immunoprecipitation, we now find that one of the papillomavirus-associated proteins (pvp1) is a highly gl ... | 1991 | 1645780 |
| nucleotide sequence of human papillomavirus (hpv) type 41: an unusual hpv type without a typical e2 binding site consensus sequence. | the complete nucleotide sequence of human papillomavirus type 41 (hpv-41) has been determined. hpv-41 was originally isolated from a facial wart, but its dna has subsequently been detected in some skin carcinomas and premalignant keratoses (grimmel et al., int. j. cancer, 1988, 41, 5-9; de villiers, grimmel and neumann, unpublished results). the analysis of the cloned hpv-41 nucleic acid reveals that its genome organisation is characteristic as for other papillomavirus types. yet, the analysis i ... | 1991 | 1645904 |
| [papillomatosis of cattle and its relationship to equine sarcoid]. | the aetiology and the pathogenesis of equine sarcoids are described. aspects of therapy are discussed. | 1991 | 1646494 |
| topological properties of bovine papillomavirus type 1 (bpv-1) dna in episomal nucleoprotein complexes: a model system for chromatin organization in higher eukaryotes. | sedimentation analysis of isolated episomal bovine papillomavirus type 1 (bpv-1) nucleoprotein complexes in sucrose gradients and subsequent separation of the purified dna in chloroquine gels revealed different classes of molecules, varying in their degree of superhelicity. since torsionally stressed dna favors the adoption of secondary structures, we employed the single-strand-specific s1 nuclease to detect such structural alterations in both naked dna and native chromatin. direct examination o ... | 1991 | 1648363 |
| formation of the complex of bovine papillomavirus e1 and e2 proteins is modulated by e2 phosphorylation and depends upon sequences within the carboxyl terminus of e1. | the 68-kda bovine papillomavirus (bpv) type 1 replication protein e1 and the 48-kda transactivator protein e2 form a complex that specifically binds dna [mohr, i.j., clark, r., sun, s., androphy, e.j., macpherson, p. & botchan, m.r. (1990) science 250, 1694-1699]. we have confirmed this observation and shown that the e1-e2 complex binds to dna fragments that contain the bpv plasmid maintenance sequence 1 and a site for the initiation of bidirectional bpv dna synthesis. the e1 protein was found t ... | 1991 | 1648739 |
| bovine papillomavirus e5 oncoprotein binds to the 16k component of vacuolar h(+)-atpases. | the major transforming protein of bovine papillomavirus type 1, e5, is mainly associated with endomembranes, specifically binding to a cellular protein of relative molecular mass 16,000 (16k). at the same time as transformation, e5 causes the phosphorylation of tyrosine residues in epidermal and platelet-derived growth factor receptors. we show here that the 16k protein associated with e5 is the 16k component of vacuolar atpases. this protein is known to be an integral membrane protein in endoso ... | 1991 | 1649407 |
| expression of epidermal growth factor precursor cdna in animal cells. | this chapter outlines in detail the optimal conditions for the expression of human recombinant proteins in mouse cells using a bovine papillomavirus-based mammalian expression vector. the procedures we have described were used to successfully express high levels of the human egf precursor in our laboratory and the human insulin receptor in the laboratory of whittaker. using this experimental approach we were able to demonstrate that expression of a cdna for prepro-egf produces a glycosylated mem ... | 1991 | 1649948 |
| in vitro "progression" of bovine papillomavirus-transformed cells: loss of contact sensitivity after multiple rounds of selection. | the transformed phenotype of c127 cells harboring bovine papillomavirus shuttle vector pdbpvmmt neo(342-12) was suppressed by direct contact with untransformed c127 cells. by repeated selections of rare foci developing on untransformed cell monolayers, we obtained a cellular clone of bpv transformants which formed foci on the untransformed c127 cells as efficiently as on plastic surface. the bpv genome in the mutant cells showed extensive genetic rearrangements, duplication of upstream regulator ... | 1991 | 1650331 |
| characterization of bpv-like dna in equine sarcoids. | the dna from equine sarcoid samples from new york state and switzerland was isolated and probed with bovine papillomavirus type 1 (bpv-1) to determine if bpv genomes were present. twelve of 13 sarcoids from new york state and 17/20 sarcoids from switzerland contained dna that hybridized to the bpv-1 probe. restriction enzyme analysis of the positive samples demonstrated restriction fragment profiles characteristic of bpv-1 in 22 sarcoids and restriction fragment profiles characteristic of bovine ... | 1991 | 1650553 |
| in vitro interactions between bovine papillomavirus and human monocytes and macrophages. | limited data suggest that macrophages play a role in the pathogenesis of bovine papillomavirus (bpv) infections. in the present study, interactions between these cells and bpv-1 were explored by exposing in vitro human blood monocytes and monocyte-derived macrophages to purified virions. immediately or up to 28 days after exposure, cell culture supernatants as well as cell lysates were collected. interleukin 1 activity was detected in the supernatants of monocytes early after exposure to bpv (0- ... | 1991 | 1650765 |
| initiation of transcription from the minute virus of mice p4 promoter is stimulated in rat cells expressing a c-ha-ras oncogene. | transformation of fr3t3 rat fibroblasts by a c-ha-ras oncogene but not by bovine papillomavirus type 1 is associated with an increase in the abundance of mrnas from prototype strain mvmp of infecting minute virus of mice, an oncosuppressive parvovirus. this differential parvovirus gene expression correlates with the reported sensitization of ras- but not bovine papillomavirus type 1-transformed cells to the killing effect of mvmp (n. salomé, b. van hille, n. duponchel, g. meneguzzi, f. cuzin, j. ... | 1991 | 1651412 |
| studies on vaccination against papillomaviruses: prophylactic and therapeutic vaccination with recombinant structural proteins. | the l1 and l2 proteins of bpv-2 have been produced in escherichia coli as beta-galactosidase fusion proteins. the fusion proteins have been used to vaccinate calves both prophylactically and therapeutically. the l1 fusion protein prevented tumor formation when administered before challenge with bpv-2, while the l2 fusion protein was very effective in promoting tumor rejection, independently from whether it was administered before or after challenge. animals vaccinated with l1, but not with l2, r ... | 1991 | 1651594 |
| [detection of bovine papillomavirus dna in equine sarcoids using the polymerase chain reaction (pcr)]. | unfixed and formalin-fixed frozen sections and paraffin-sections of histopathologically confirmed sarcoids of 20 horses were studied in the pcr. the used set of primers was located in the e5 open reading frame fitting both to bovine papillomavirus 1 (bpv-1) and bpv-2. independent of the quality of the used tissues bpv-dna was detected in all 20 sarcoids. by cleaving with restriction endonuclease bst xi it was shown that the dna-sequences amplified by pcr were identical with that of bpv-1. the re ... | 1991 | 1652932 |
| illegitimate recombination in a bovine papillomavirus shuttle vector: a high level of site specificity. | recombination in a bovine papillomavirus shuttle vector carrying direct repeats of moloney murine leukemia virus ltr sequence was examined. differently from similar vectors carrying direct repeats of sv40 polya addition signal or neomycin resistance gene, the vector exhibited no homologous recombination between the repeats. instead, illegitimate recombination took place. there were two major types of recombination products from the restriction cleavage pattern. the plasmids in independent cellul ... | 1991 | 1652950 |
| the functional bpv-1 e2 trans-activating protein can act as a repressor by preventing formation of the initiation complex. | the products encoded by the e2 open reading frame of the papillomaviruses are dna-binding transcription factors involved in the positive or negative regulation of multiple viral promoters. to further understand the mechanisms by which the same transcription factor may act differentially, the full-length bpv-1 e2 protein was expressed and purified from yeast and assayed in vitro for its capacity to modulate transcription. e2 stimulated transcription of the hsv thymidine kinase (tk) promoter when ... | 1991 | 1653173 |
| [implantation of genetically manipulated fibroblasts into mice as a model of gene therapy--supplementations of human granulocyte colony-stimulating factor (hg-csf) and interferon-alpha (ifn-alpha)]. | implantation of genetically manipulated fibroblasts is now coming considered to be one of the important methods for gene therapy. before the clinical application of this method, we still need to resolve several problems encountered. we have recently developed a model system for the fibroblast-mediated cytokine supplementation gene therapy. bmgneo (bovine papilloma virus-derived plasmid) (gifted from dr. karasuyama) was used for expression of hg-csf cdna or hifn-alpha cdna (gifted from dr. nagata ... | 1991 | 1653596 |
| immunofluorescent detection of bovine papillomavirus e4 antigen in the cytoplasm of cells permissive in vitro for viral dna amplification. | the e4 gene of several human papillomavirus types is expressed in association with vegetative viral dna synthesis in differentiated epidermal cells. to develop reagents to study expression of the bovine papillomavirus type 1 (bpv-1) e4 gene in warts and in virus-transformed cell lines, rabbit polyclonal antiserum was raised to the bpv-1 e4 antigen produced as a fusion polypeptide in escherichia coli. by immunoblotting analysis of productively infected bovine fibropapilloma tissue, e4-related pro ... | 1991 | 1654378 |
| a bovine papillomavirus e1-related protein binds specifically to bovine papillomavirus dna. | the e1 open reading frame of bovine papillomavirus (bpv) was expressed as a reca-e1 fusion protein in escherichia coli. the bacterially expressed reca-e1 protein exhibited sequence-specific dna binding activity; strong binding to the region from nucleotides 7819 to 93 on the bpv genome (designated region a) and weak binding to the adjacent region from nucleotides 7457 to 7818 (region b) were observed. the interaction between the bpv-derived reca-e1 protein and region a appeared to be highly spec ... | 1991 | 1654443 |
| the b subgroup bovine papillomaviruses lack an identifiable e6 open reading frame. | analysis of the corrected dna sequence for the bovine papillomavirus type 4 (bpv4) genome revealed that there is no open reading frame (orf) that might encode an e6 protein. the other two b subgroup bovine papillomaviruses, bpv3 and bpv6, were found to have the same arrangement of orfs in this region as bpv4. thus, we conclude that e6 functions are either not required by these viruses or are performed by another viral (or host) protein. furthermore, the position that might be expected to be occu ... | 1991 | 1654923 |
| [comparison of vector properties of the usual and modified sequences of the bpv-1 genome]. | | 1991 | 1655372 |
| several different upstream promoter elements can potentiate transactivation by the bpv-1 e2 protein. | the enhancer and upstream promoter regions of rna polymerase ii transcribed genes modulate the rate of transcription initiation and establish specific patterns of gene expression. both types of region consist of clusters of dna binding sites for nuclear proteins. to determine how efficiently the same factor can activate transcription when acting as an enhancer or promoter factor, we have studied transactivation by the bpv-1 e2 protein, a papillomavirus transcriptional regulator. by cotransfectin ... | 1991 | 1655407 |
| the papillomavirus e2 regulatory proteins. | | 1991 | 1655748 |
| regulation of early gene expression from the bovine papillomavirus genome in transiently transfected c127 cells. | expression of bovine papillomavirus (bpv) early gene products is required for viral dna replication and establishment of the transformed phenotype. by the use of a highly efficient electroporation system, we have examined for the first time the transcriptional activity of bpv promoters in their natural genomic context in a replication-permissive cell line. we have determined that a qualitatively distinct stage of transcription is not detectable prior to dna replication in transiently transfected ... | 1991 | 1656065 |
| activation of bpv-1 replication in vitro by the transcription factor e2. | soluble extracts from uninfected murine cells supplemented with purified viral e1 and e2 proteins support the replication of exogenously added papilloma virus dna. the e2 transactivator stimulates the binding of the e1 replication protein to the minimal origin of replication and activates dna replication. these results support the concept that transcription factors have a direct role in the initiation of dna replication in eukaryotes by participating in the assembly of a complex at the origin of ... | 1991 | 1656277 |
| native yeast telomeres are sufficient to stabilize linear dna in xenopus laevis oocytes. | we have constructed a linear plasmid in yeast containing the entire bovine papillomavirus genome and tested its physical stability following microinjection into stage vi oocytes of xenopus laevis. our results show that unmodified telomeres, in contrast to the yeast-passaged telomeres, drastically affect the stability of the injected linear plasmid. plasmids carrying unmodified tetrahymena thermophila telomeric sequences are rapidly degraded in oocytes. when these plasmids are passed through yeas ... | 1991 | 1657721 |
| bovine papillomavirus with a mutation in the e2 serine 301 phosphorylation site replicates at a high copy number. | the e2 open reading frame of bovine papillomavirus type 1 (bpv-1) encodes at least three proteins with transcriptional regulatory properties. the full-length e2 open reading frame encodes a transcriptional transactivator, and the 3' region encodes two smaller polypeptides that repress e2-mediated transactivation. the full-length gene product is also required for viral dna replication. we have demonstrated that the bpv-1 e2 polypeptides are phosphorylated primarily on two serine residues at a sit ... | 1991 | 1658358 |
| tumorigenic transformation of murine keratinocytes by the e5 genes of bovine papillomavirus type 1 and human papillomavirus type 16. | to examine the biological properties of the bovine papillomavirus type 1 (bpv) and human papillomavirus type 16 (hpv16) e5 genes, each was cloned separately into a retroviral expression vector and helper-free recombinant viruses were generated in packaging cell lines. the bpv e5 retroviruses efficiently caused morphologic and tumorigenic transformation of cultured lines of murine fibroblasts, whereas the hpv16 e5 viruses were inactive in these assays. in contrast, infection of the p117 establish ... | 1991 | 1658398 |
| the bovine papillomavirus e5 oncogene can cooperate with ras: identification of p21 amino acids critical for transformation by c-rash but not v-rash. | we have previously used a series of insertion-deletion mutants of the mutationally activated v-rash gene to identify several regions of the encoded protein that are dispensable for cellular transformation (b. m. willumsen, a. g. papageorge, h.-f. kung, e. bekesi, t. robins, m. johnsen, w. c. vass, and d. r. lowy, mol. cell. biol. 6:2646-2654, 1986). to determine if some of these amino acids are more important for the biological activity of c-rash, we have now tested many of the same insertion-de ... | 1991 | 1658623 |
| efficient selection for high-expression transfectants with a novel eukaryotic vector. | we have developed a new expression vector which allows efficient selection for transfectants that express foreign genes at high levels. the vector is composed of a ubiquitously strong promoter based on the beta-actin promoter, a 69% subregion of the bovine papilloma virus genome, and a mutant neomycin phosphotransferase ii-encoding gene driven by a weak promoter, which confers only marginal resistance to g418. thus, high concentrations of g418 (approx. 800 micrograms/ml) effectively select for t ... | 1991 | 1660837 |
| cell transformation induced by bovine papillomavirus dna as an assay for tumor promoters and chemopreventive agents. | an in vitro assay was designed to examine and quantitate the action of chemical promoters and chemopreventive agents on papillomavirus dna-carrying cells. cultured c3h/10t1/2 cells transfected with bovine papillomavirus type 1 dna (plasmid pdbpv-1) were used as targets, and the frequency of transformed foci was used as an endpoint. the development of foci with a transformed phenotype was greatly enhanced by tumor promoters (e.g., mezerein, 12-o-tetradecanoyl-phorbol-13-acetate, teleocidin, and o ... | 1991 | 1661204 |
| high rotational mobility of dna in animal cells and its modulation by histone acetylation. | dna rotational mobility in a bovine papilloma virus (bpv)-based minichromosome, autonomously replicating in mouse cells, was studied using topoisomer analysis in temperature shift experiments. it was found that in live cells the average number of topological turns increased by six in the course of temperature shift through a range of 37 degrees c. this comprised approximately 85% of the total potential mobility of naked plasmid dna. dna rotation in isolated nuclei was found to be 3.5-4.0 turns p ... | 1991 | 1661371 |
| [recombinant murine cell lines transformed by various vectors based on bovine papillomavirus type 1 and expressing human tissue plasminogen activator]. | we have constructed a number of vectors which include transcriptional unit of human tpa cdna and 100% bpv-1 dna or 100% lx dna (mutant bpv variant with tandem duplication of lcr-e6-e7 region). additional hsv-1 tk-promoter was inserted in the flanks of viral dnaa in a set of constructions. a number of recombinant cell lines have been established by means of transformation using the constructed vectors. the increased focus formation activity and the improved vector properties were demonstrated for ... | 1991 | 1661373 |